JP2015203458A - drum brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility that over-adjustment occurs, in a drum brake device which operates by an electric actuator.SOLUTION: When a parking brake signal is turned off (S21: Yes), a parking brake ECU determines whether or not a stop maintenance time Ts at which a vehicle is maintained in a stop state is longer than a set time T0 (S22). When the stop maintenance time Ts is longer than the set time T0, it can be estimated that a brake drum is not thermally expanded. In this case, the parking brake ECU reversely drives a motor, and stops the motor at timing at which a rotation amount R of the motor reaches a set rotation amount R1 from a time point at which a motor current im becomes constant (time point at which a brake shoe is separated from the brake drum) (S23 to S29).

Description

  The present invention relates to a drum brake device mounted on a vehicle.

  Conventionally, the drum brake device has been provided with an automatic adjuster that automatically adjusts the standby position of the brake shoe so that the gap between the brake drum and the brake shoe during non-braking (referred to as shoe clearance) does not increase due to wear of the brake shoe. It has been. In general, the automatic adjuster has a strut that regulates the minimum distance between a pair of brake shoes. When the brake shoes are greatly expanded during normal brake operation, that is, when the shoe clearance is increased, the adjuster bolt is rotated. To extend the strut. As a result, the minimum distance between the pair of brake shoes is increased and the shoe clearance is automatically adjusted.

  Patent Document 1 proposes a drum brake device that includes an electric actuator that expands a brake shoe by an electric motor between a pair of brake shoes. This drum brake device is configured to perform a service brake operation, a parking brake operation, and a shoe clearance adjustment by a common electric actuator.

3-591919

  The automatic adjuster is provided to operate when the range of movement of the brake shoe is increased due to wear of the brake shoe, but if the brake drum is temporarily deformed, It may work. For example, when the brake drum becomes hot and thermally expands due to friction between the brake shoe and the brake drum, the drum diameter increases, so that the automatic adjuster operates in the same way as when the brake shoe wears, Excessive spacing between brake shoes. When the brake drum returns to normal temperature, the drum diameter also returns. For this reason, a phenomenon in which the shoe clearance to be secured during non-braking becomes less than an appropriate value, so-called over-adjustment, occurs.

  Even when a strong brake operation is performed, the brake shoe strongly presses the brake drum in the expanding direction, so that the drum diameter temporarily increases and the brake shoe lining temporarily compresses and deforms. . Further, at the time of brake operation during traveling, the lining temporarily deforms in the direction of the braking torque (this deformation is called shear deformation). Even in such a case, over adjustment occurs.

  When over-adjustment occurs, friction between the brake drum and the lining occurs even though the brake pedal operation is not performed, leading to early wear of the lining and deterioration of fuel consumption of the vehicle. Therefore, conventionally, the adjustment amount of the automatic adjuster is set in anticipation of temporary deformation of the drum brake device itself. However, since the shoe clearance is increased by the amount of deformation, the brake operation feeling is not good. .

  The drum brake device proposed in Patent Document 1 adjusts the shoe clearance using an electric actuator without using a strut. However, the timing for adjusting the shoe clearance is not set, and over-adjustment may occur due to deformation of the brake drum.

  An object of the present invention is to cope with the above-described problem, and is to reduce the possibility of occurrence of over-adjustment in a drum brake device operated by an electric actuator.

In order to achieve the above object, the drum brake device according to the present invention is characterized by including a motor (60) and expanding a pair of brake shoes (30) by changing an operation amount by driving the motor. A first actuator (50) for pressing the brake drum (10) with the brake shoe to brake the wheel;
The operation amount of the first actuator is increased in accordance with the first braking request, and the pair of brake shoes are expanded from the standby position to the braking position to bring the wheels into a braking state, and in accordance with the first braking release request, the first actuator A drum brake device comprising: a first actuator control device (120) for reducing the operation amount of the pair of brake shoes to return the pair of brake shoes from the braking position to the standby position to bring the wheels into a non-braking state;
The first actuator control device includes:
Drum temperature index value acquisition means (S41 to S43, S51 to S53) for acquiring a parameter having a correlation with the temperature of the brake drum as a drum temperature index value (Ts);
When the first brake release request is generated, the drum temperature index value is within an allowable range of the thermal expansion amount of the brake drum in the process in which the brake shoe is returned from the braking position to the standby position by the first actuator. When the operation amount of the first actuator decreases by a predetermined amount from the operation amount at the time when it is estimated that the contact between the brake shoe and the brake drum has been released, on the condition that Standby position updating means (S23 to S29) for updating the position of the pair of brake shoes as the standby position.

  The drum brake device of the present invention includes a first actuator that presses the brake drum with the brake shoe to brake the wheel by expanding the pair of brake shoes by changing the operation amount by driving the motor. ing. The motor of the first actuator is driven and controlled by the first actuator controller. The first actuator control device increases the operation amount of the first actuator in accordance with the first braking request, and widens the pair of brake shoes from the standby position to the braking position, thereby braking the wheel. Further, the first actuator control device reduces the operation amount of the first actuator in accordance with the first braking release request and returns the pair of brake shoes from the braking position to the standby position, thereby bringing the wheel into a non-braking state. The first braking request and the first braking release request are generated, for example, by a driver's brake operation, but may be generated along with automatic driving control, behavior stabilization control, or the like of the vehicle. In the present specification, “braking the wheel” means not only reducing the rotational speed of the rotating wheel but also preventing the stopped wheel from rotating. Used in. Therefore, the first actuator may be used as a service brake or may be used as a parking brake.

  When the brake drum becomes hot due to friction between the brake shoe and the brake drum, the drum diameter increases due to thermal expansion of the brake drum. If the standby position of the brake shoe is set in such a situation, the clearance between the brake shoe and the brake drum becomes too small when the temperature of the brake drum drops to room temperature. That is, over adjustment occurs. Therefore, in the present invention, the clearance at the standby position is made appropriate by the drum temperature index value acquisition means and the standby position update means.

  The drum temperature index acquisition unit acquires a parameter having a correlation with the temperature of the brake drum as a drum temperature index value. Based on this drum temperature index value, it is possible to determine whether or not the thermal expansion amount of the brake drum that causes over-adjustment is within an allowable range. For example, a detected temperature obtained by detecting the temperature of the brake drum may be used as the drum temperature index value, or a vehicle stoppage maintenance time that is a time during which the brake drum does not generate heat may be used. When the vehicle stop maintenance time is used, for example, when the vehicle stop maintenance time is equal to or longer than the set time, the drum temperature index value indicates that the thermal expansion amount is within an allowable range. Note that the thermal expansion amount of the brake drum represents, for example, the amount of thermal expansion based on the shape of the brake drum at normal temperature (previously assumed temperature). The temperature at which the thermal expansion amount falls within the allowable range (the temperature that does not easily affect the setting of the standby position) may be set based on the material of the brake drum, the target clearance, and the like.

  The standby position update means is configured so that when the first brake release request is generated, the drum temperature index value is within the allowable range of the brake drum index value in the process of returning the brake shoe from the brake position to the standby position by the first actuator. A pair of brakes when the operation amount of the first actuator is reduced by a predetermined amount from the operation amount at the time when it is estimated that the contact between the brake shoe and the brake drum is released. The shoe position is updated as the standby position. Therefore, the standby position can be set in a state that is not easily affected by the thermal expansion of the brake drum. Further, the standby position can be set in a state in which the pressure on the brake drum by the first actuator is released. As a result, according to the present invention, the possibility of occurrence of over-adjustment due to the deformation of the brake drum can be reduced. The predetermined amount is an amount corresponding to the target clearance between the brake drum and the brake shoe, and may be set based on the rotation amount of the motor or may be set based on the energization time of the motor. .

According to one aspect of the present invention, a second actuator (40) different from the first actuator, which presses the brake drum with the brake shoe to brake the wheel by expanding the pair of brake shoes,
The wheels are braked by expanding the pair of brake shoes from the updated standby position according to a second braking request, and the pair of brake shoes are returned to the updated standby position according to a second braking release request. A second actuator control device (110, 200) for bringing the wheel into a non-braking state by
The first actuator control device operates the first actuator in accordance with a braking request generated by a parking brake operation as the first braking request and a braking release request generated by the parking brake operation as the first braking release request. Control
The second actuator control device operates the second actuator in accordance with a braking request generated by a service brake operation as the second brake request and a brake release request generated by the service brake operation as the second brake release request. There is to control.

  A drum brake device according to one aspect of the present invention includes a first actuator and a second actuator. The first actuator control device controls the operation of the first actuator in accordance with a braking request generated by a parking brake operation as a first braking request and a braking release request generated by a parking brake operation as a first braking release request. The second actuator control device controls the operation of the second actuator according to the braking request generated by the service brake operation as the second braking request and the brake release request generated by the service brake operation as the second brake release request.

  For example, when the brake pedal is strongly depressed during traveling and the service brake is activated, the amount of deformation of the brake drum and the amount of deformation of the lining are larger than when the parking brake is activated while the vehicle is stopped. For this reason, if a standby position (clearance) is set during operation of the second actuator, over-adjustment tends to occur. On the other hand, in one aspect of the present invention, the standby position is updated when the braking of the first actuator that is operated by the parking brake operation is released. For this reason, it is not necessary to update the standby position when the service brake is operated, an appropriate standby position can be set, and the possibility of occurrence of over-adjustment can be reduced.

  The second actuator can be constituted by a hydraulic cylinder that is operated by the hydraulic pressure of the brake hydraulic fluid, for example. In this case, the second actuator control device can be configured by a hydraulic pressure control device that supplies the hydraulic pressure of the brake hydraulic fluid corresponding to the service brake operation to the hydraulic cylinder. The second actuator is not limited to a hydraulically operated type, and may be, for example, a pneumatically operated type or an electric type.

  One aspect of the present invention is that the first actuator control device is configured to update the standby position on condition that the brake shoe is not pressing the brake drum by the second actuator. is there.

  In a situation where the second actuator presses the brake shoe against the brake drum by the regular brake operation, the drum diameter temporarily increases or the lining of the brake shoe is deformed. Therefore, the first actuator control device updates the standby position on condition that the brake shoe is not pressing the brake drum by the second actuator. Thus, according to one aspect of the present invention, an appropriate standby position (clearance) can be set, and the possibility of occurrence of over-adjustment can be reduced.

  In one aspect of the present invention, when the first brake release request is generated, the first actuator control device is configured such that when the brake shoe presses the brake drum by the operation of the second actuator, After waiting until the actuator releases the pressure on the brake drum by the brake shoe (S221), the first actuator is operated to release the pressure on the brake drum by the brake shoe. It is in.

  According to one aspect of the present invention, when the first brake release request is generated by the parking brake operation, when the brake shoe presses the brake drum by the operation of the second actuator, the second actuator is the brake drum by the brake shoe. After waiting until the pressure on the brake is released, that is, until the service brake operation is released, the first actuator is operated to release the pressure on the brake drum by the brake shoe. Therefore, the standby position can be updated in a situation where the brake drum is not deformed. As a result, according to one aspect of the present invention, an appropriate standby position can be set, and the possibility of occurrence of over-adjustment can be reduced.

  In one aspect of the present invention, the second actuator control device is configured such that the second brake request is generated even when the second braking request is generated in a state where the brake shoe presses the brake drum by the operation of the first actuator. The present invention resides in that the brake shoe is not pressed against the brake drum by the operation of the actuator (S20, S64).

  When the brake shoe is pressing the brake drum by the second actuator, the brake drum may be deformed by the pressing force. When the standby position is set based on the operation amount of the first actuator at the time when it is estimated that the contact between the brake shoe and the brake drum is released by the first actuator when the brake drum is deformed, The standby position may be inappropriate. Therefore, in one aspect of the present invention, the second actuator control device performs the second braking in a state where the brake shoe presses the brake drum by the operation of the first actuator, that is, in a state where the parking brake functions. Even if the request occurs, the brake shoe is not pressed against the brake drum by the operation of the second actuator.

  Therefore, when the contact between the brake shoe and the brake drum is released by the first actuator, that is, when the parking brake is released, the brake actuator is deformed because the second actuator is inactive. Not. For this reason, according to one aspect of the present invention, an appropriate standby position can be set, and the possibility of occurrence of over-adjustment can be reduced. Even when the brake shoe is not pressed against the brake drum by the operation of the second actuator, the brake shoe is kept pressed against the brake drum by the operation of the first actuator. Can be maintained.

  In one aspect of the present invention, the drum temperature index value acquisition unit is configured to calculate a stop maintenance time that has been stopped when a first brake release request for releasing a braking state of a wheel by the first actuator is generated during a stop. It is obtained as the drum temperature index value.

  The brake drum is in a high temperature state due to frictional heat generated by friction with the brake shoe. However, if frictional heat is not generated as the wheel stops rotating, the brake drum is cooled by the atmosphere and becomes low over time. Therefore, in one aspect of the present invention, the stoppage maintaining time during which the drum temperature index value acquisition unit is maintained stopped when the first braking release request for releasing the braking state of the wheel by the first actuator is generated while the vehicle is stopped. As a drum temperature index value. Therefore, when the vehicle stop keeping time is equal to or longer than a preset time, it can be determined that the thermal expansion amount of the brake drum is within the allowable range. The stop maintenance time may be obtained, for example, as the time during which the vehicle speed was maintained at zero, but instead, the time during which the parking brake was functioning may be obtained as the stop maintenance time. Therefore, according to one aspect of the present invention, the drum temperature index value can be acquired without directly detecting the temperature of the brake drum by the temperature sensor, and can be implemented at low cost.

In one aspect of the present invention, the first actuator (50) includes the motor (60), a worm (71) fixed to an output shaft of the motor, a worm wheel (72) meshing with the worm, A screw feed mechanism (80) that converts the rotational operation of the worm wheel into an advance / retreat operation of the operating body (82), and the mutual distance between the one end sides of the pair of brake shoes is changed by the advance / retreat operation of the operating body Configured as
The second actuator includes a cylinder (40) having a piston that moves forward and backward by a brake hydraulic fluid supplied by the second actuator control device, and a mutual distance between the other ends of the pair of brake shoes by the forward and backward movement of the piston. Is configured to change.

  In the drum brake device according to one aspect of the present invention, the first actuator changes the mutual distance on one end side of the pair of brake shoes, and the second actuator changes the mutual distance on the other end side of the pair of brake shoes. In the first actuator, the energization of the motor is controlled by the first braking request generated by the parking brake operation or the first braking release request. When the motor is energized, the output shaft of the motor rotates, and accordingly, a worm gear having a worm and a worm wheel rotates. The rotating operation of the worm wheel is converted into an advancing / retreating operation of the operating body by the screw feed mechanism, and the mutual distance on one end side of the pair of brake shoes is changed by the advancing / retreating operation of the operating body. Due to the characteristics of the worm gear, in the first actuator, when the brake shoe is held at the braking position, the energization of the motor can be stopped.

  The second actuator is supplied with brake hydraulic fluid having a hydraulic pressure corresponding to the service brake operation from the second actuator controller to the cylinder, and moves the piston forward or backward. By the advance / retreat operation of the piston, the mutual distance on the other end side of the pair of brake shoes is changed. Therefore, according to one aspect of the present invention, the operation of the parking brake and the operation of the service brake can be appropriately performed independently.

In one aspect of the present invention, the first actuator is configured such that motor torque required to move the brake shoe decreases as the force with which the brake shoe presses the brake drum decreases.
The first actuator control device is configured to maintain a constant state from a decreasing state in which the current of the motor decreases in a process in which the brake shoe is returned from the braking position to the standby position by driving the motor. It is configured to estimate the time point when switching to the time point when the contact between the brake shoe and the brake drum is released (S26).

  The first actuator used in one aspect of the present invention is configured such that the motor torque required to move the brake shoe decreases as the force with which the brake shoe presses the brake drum decreases. . In this case, in the process in which the brake shoe is returned from the braking position to the standby position by driving the motor, the motor current decreases while the brake shoe is in contact with the brake drum, and the contact between the brake shoe and the brake drum occurs. When is released, it remains at a constant value. Therefore, in one aspect of the present invention, the first actuator control device maintains a constant value from a decreasing state in which the motor current decreases while the brake shoe is returned from the braking position to the standby position by driving the motor. It is estimated that the point in time when switching to the fixed state is released is the point at which the contact between the brake shoe and the brake drum is released. For this reason, estimation of contact release timing can be performed appropriately and easily. Therefore, the standby position can be set appropriately and easily.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiment in parentheses, but each constituent element of the invention is the reference numeral. It is not limited to the embodiment defined by.

It is a front schematic lineblock diagram of a drum brake concerning an embodiment. 1 is a system schematic configuration diagram of a drum brake device according to an embodiment. It is a side surface schematic sectional drawing of an electric actuator. It is a front schematic sectional drawing of an electric actuator. It is the end surface schematic of a wheel cylinder. It is a flowchart showing a parking brake operation control routine. It is a flowchart showing a parking brake release control routine. It is a flowchart showing a stop time measuring routine. It is a flowchart showing another stop time measuring routine. It is a flowchart showing the parking brake action control routine which concerns on a 1st modification. It is a flowchart showing the parking brake cancellation | release control routine which concerns on a 1st modification. It is a flowchart showing the hydraulic-pressure supply command routine which concerns on a 2nd modification. It is a flowchart showing the parking brake action control routine which concerns on a 3rd modification. It is a flowchart showing the parking brake cancellation | release control routine which concerns on a 3rd modification. It is a graph showing transition of motor current. It is explanatory drawing which represents typically the meshing state of a worm gear mechanism.

  Hereinafter, a drum brake device for a vehicle according to an embodiment of the present invention will be described. FIG. 1 schematically shows a drum brake 1 for a rear wheel provided in a drum brake device according to the present embodiment. The drum brake 1 includes a brake drum 10, a back plate 20, two pairs of brake shoes 30 a and 30 b, a wheel cylinder 40, and an electric actuator 50.

  The brake drum 10 is a cylindrical body that rotates with the wheel, and a friction surface is formed on the inner peripheral surface thereof. The back plate 20 has a substantially disk shape and is fixed to the vehicle body side member so as not to rotate. The pair of brake shoes 30a and 30b are members having an arc shape, and are accommodated in the brake drum 10 so as to be substantially left and right so as to be close to and away from each other. Hereinafter, when it is not necessary to specify one of the two brake shoes 30a and 30b, both are simply referred to as the brake shoe 30.

  Each brake shoe 30 is fixed to a shoe web 31 disposed substantially parallel to the plate surface (one surface side) of the back plate 20, a shoe rim 32 fixed to the outer peripheral side end surface of the shoe web 31, and an outer peripheral surface of the shoe rim 32. A lining 33 that frictionally engages with the inner peripheral surface of the brake drum 10 when the brake is operated is integrally provided. Each brake shoe 30 is attached to the back plate 20 so as to be movable toward the inner peripheral surface of the brake drum 10 by a shoe hold-down 21 that is attached to an attachment hole formed through each shoe web 31.

  A wheel cylinder 40 as a hydraulic actuator is fixed to the back plate 20 between one ends (in this example, upper ends) of the pair of brake shoes 30a and 30b. The wheel cylinder 40 includes pistons 41 that are operated by the pressure of the brake hydraulic fluid at both ends. The tip of the piston 41 is connected to one end of the left and right shoe webs 31. The wheel cylinder 40 expands the brake shoe 30 by pressing the left and right shoe webs 31 in the direction of separating the piston 41 by advancing the piston 41 by the hydraulic pressure of the brake hydraulic fluid supplied from the hydraulic pressure supply circuit 200 described later. Let it open. As a result, the lining 33 is pressed against the inner peripheral surface of the brake drum 10, and a friction braking force is generated to stop the rotation of the brake drum 10 (that is, the rotation of the wheel). Further, when the hydraulic pressure of the brake hydraulic fluid supplied from the hydraulic pressure supply circuit 200 decreases, the wheel cylinder 40 retracts the piston 41 and draws the left and right shoe webs 31 to the inner peripheral surface of the brake drum 10 by the lining 33. Release the pressure. Thereby, the braking state of the wheel is released.

  As shown in FIG. 5, the piston 41 is not pushed into the housing of the wheel cylinder 40 from the initial position (position when no hydraulic pressure is supplied) by the operation of an electric actuator 50 described later. A stopper receiver 42 is formed on the surface. In a situation where the piston 41 is disposed at the initial position, the stopper 34 formed on the shoe web 31 is configured to contact the stopper receiver 42.

  An electric actuator 50 is provided between the other ends (the lower ends in this example) of the pair of brake shoes 30a and 30b. The electric actuator 50 is controlled by a parking brake ECU 120 described later, and when the driver operates the parking brake, the electric shoe 50 presses the left and right shoe webs 31 in the direction of separating the brake shoes 30 from each other. Expand. Thereby, the lining 33 is pressed against the inner peripheral surface of the brake drum 10, and the brake drum 10 is maintained in the stopped state, that is, the parking brake is in effect. Further, the electric actuator 50 pulls the left and right shoe webs 31 back to the standby position when the parking brake is released by the driver. Thereby, the parking brake is released.

  As shown in FIGS. 3 and 4, the electric actuator 50 includes a motor 60, a worm gear mechanism 70, and a screw feed mechanism 80. The motor 60 is fixed to the back surface of the back plate 20 with the output shaft 61 passing through the back plate 20. A worm 71 is fixed to the output shaft 61 of the motor 60. The screw feed mechanism 80 includes a cylindrical screw member 81 and two advance / retreat rods 821 and 822. A worm wheel 72 is fixed to the screw member 81 on the outer peripheral surface of the cylindrical main body. The worm wheel 72 is fixed at a coaxial position with respect to the screw member 81 and meshes with the worm 71 fixed to the output shaft 61 of the motor 60. The worm 71 and the worm wheel 72 constitute a worm gear mechanism 70.

  The worm gear mechanism 70 and the screw member 81 are housed in a casing (not shown). The screw member 81 is rotatably provided in the casing in a state where movement in the axial direction is prevented by a bearing (not shown). Thereby, when the motor 60 is driven and the output shaft 61 rotates, the screw member 81 is decelerated via the worm gear mechanism 70 and rotates.

  A first female screw 811 is formed on one side (left side in the drawing) of the cylindrical body portion of the screw member 81 on the one side (left side in the drawing) from the center in the axial direction, and on the other side (right side in the drawing) from the center in the axial direction. Two internal threads 812 are formed. The first female screw 811 and the second female screw 812 have the same lead and diameter, but are formed so that the screw forming directions are opposite to each other. For example, the first female screw 811 is a right-hand screw, and the second female screw 812 is a left-hand screw.

  In the cylindrical space of the screw member 81, a cylindrical first advance / retreat rod 821 formed with a male screw 8211 meshing with the first female screw 811 and a second advance / retreat rod formed with a male screw 8221 meshed with the second female screw 812 are formed. 822 is provided. Therefore, the rotational motion of the screw member 81 is converted into linear motion (advance / retreat motion) between the first advance / retreat rod 821 and the second advance / retreat rod 822. In this case, the first advance / retreat rod 821 and the second advance / retreat rod 822 make a pair and linearly move in opposite directions. For example, the first advancing / retracting rod 821 and the second advancing / retracting rod 822 advance in a direction away from each other when the motor 60 is driven to rotate forward, and approach each other when the motor 60 is driven to rotate in the reverse direction. Retreat to.

  As described above, the screw feed mechanism 80 is configured by the screw member 81, the first advance / retreat rod 821, and the second advance / retreat rod 822. Hereinafter, when it is not necessary to specify any one of the first advance / retreat rod 821 and the second advance / retreat rod 822, both are simply referred to as the advance / retreat rod 82.

A columnar connecting portion 83 is integrally formed at the tip of each advance / retreat rod 82. A groove 84 having a U-shaped cross section that extends linearly in parallel with the back plate 20 is formed in the connecting portion 83, and the tip of the shoe web 31 is fitted and fixed in the groove 84. Therefore, when the motor 60 is driven to rotate in the forward direction, the advance / retreat rod 82 moves forward to push the shoe web 31 outward, and the distance between the brake shoes 30 is increased. Further, when the motor 60 is driven to rotate in the reverse direction, the advance / retreat rod 82 moves backward to draw the shoe web 31 inward, and the distance between the brake shoes 30 is narrowed.

  In addition, when the brake shoe 30 is pressing the brake drum 10, the electric actuator 50 is braked by the worm gear mechanism 70 and the screw feed mechanism 80 only with the reaction force (force that the brake drum 10 pushes back the brake shoe 30). The shoe 30 is configured not to be pushed back. Therefore, in a state where the brake shoe 30 is pressing the brake drum 10, the state can be maintained even if energization to the motor 60 is stopped.

  Next, a system for controlling the drum brake 1 will be described. FIG. 2 shows a schematic system configuration of the drum brake device. In a vehicle to which the drum brake device of this embodiment is applied, the above-described drum brake 1 is provided on the left and right rear wheels. The left and right front wheels are provided with a general drum brake 5 that does not include the electric actuator 50 and supports the other end of the shoe web 31 with an anchor member (not shown). In this example, the front wheel brake is a general drum brake 5, but the front wheel brake is not included in the present invention and may be a disc brake. Hereinafter, in the description of the system configuration, with respect to the configuration provided on the left front wheel, “fl” is added to the end of the reference numeral, and with respect to the configuration provided on the right front wheel, fr is added to the end of the reference numeral. For the configuration provided in, rl is added to the end of the code, and for the configuration provided in the right front wheel, rr is added to the end of the code.

  The drum brake device includes a brake electronic control unit 100 (hereinafter referred to as a brake ECU 100) and a hydraulic pressure supply circuit 200. The brake ECU 100 includes a service brake electronic control unit 110 (hereinafter referred to as service brake ECU 110) that controls the operation of the hydraulic pressure supply circuit 200, and a parking brake electronic control unit 120 (hereinafter referred to as a parking brake) that controls the operation of the electric actuator 50. ECU 120).

  The hydraulic pressure supply circuit 200 includes a wheel cylinder 6fl for the left front wheel drum brake 5fl, a wheel cylinder 6fr for the right front wheel drum brake 5fr, a wheel cylinder 40rl for the left rear wheel drum brake 1rl, and a right rear wheel drum brake. It is connected to a 1rr wheel cylinder 40rr via a brake pipe. The hydraulic pressure supply circuit 200 includes a master cylinder that pressurizes the hydraulic fluid by depressing the brake pedal 201, a reservoir that stores the hydraulic fluid at atmospheric pressure, the hydraulic pressure of the pressurized hydraulic fluid in each wheel cylinder 6fl, A hydraulic circuit for supplying 6fr, 40rl, 40rr, an on-off valve for switching the supply of hydraulic fluid to the wheel cylinders 6fl, 6fr, 40rl, 40rr of each wheel to a supplyable state and a supply prohibition state that cannot be supplied. (The above is a general configuration and is not shown). This on-off valve is, for example, an on-off valve used for anti-lock brake control for preventing the wheel from being locked for each wheel, and is capable of switching the supply state of the hydraulic fluid independently at least between the front wheel and the rear wheel. That's fine.

  The hydraulic pressure supply circuit 200 includes a sensor that detects a pressurized state of hydraulic fluid such as a pressure sensor (not shown), and outputs a sensor signal to the service brake ECU 110. In FIG. 2, broken line arrows represent sensor signal lines. The service brake ECU 110 is configured to receive a sensor signal output from the hydraulic pressure supply circuit 200 and a switch signal of the pedal switch 90 that detects whether or not the brake pedal 201 is depressed. The depression operation of the brake pedal 201 becomes a braking request (corresponding to the second braking request of the present invention), and the depression operation of the brake pedal 201 is a braking cancellation request (corresponding to the second braking cancellation request of the present invention). Become. The service brake ECU 110 receives a sensor signal indicating the behavior state of the vehicle, etc., but is omitted from this description because it is not directly related to the present invention.

  The service brake ECU 110 includes a microcomputer comprising a CPU, ROM, RAM, etc., an electromagnetic valve drive circuit, an input / output interface, and the like, and is configured to be able to communicate with the parking brake ECU 120. The control system for the service brake of the present embodiment is such that the hydraulic pressure pressurized by the master cylinder by the depression operation of the brake pedal 201 is directly supplied to the wheel cylinders 6fl, 6fr, 40rl, 40rr of each wheel, and is used regularly when necessary. The brake ECU 110 controls the hydraulic pressure supplied to the wheel cylinders 6fl, 6fr, 40rl, and 40rr of each wheel by outputting a drive signal to the on-off valve of the hydraulic pressure supply circuit 200.

  The parking brake ECU 120 includes a microcomputer including a CPU, a ROM, a RAM, a motor drive circuit, an input / output interface, and the like, and is configured to be able to communicate with the service brake ECU 110. The electric actuators 50rl and 50rr provided in the rear wheel drum brakes 1rl and 1rr include rotation angle sensors 91rl and 91rr for detecting the rotation angles of the motors 60rl and 60rr, respectively. Sensor 91) is provided. Each rotation angle sensor 91rl, 91rr outputs a sensor signal representing the rotation angle θ of the motors 60rl, 60rr to the parking brake ECU 120.

  The parking brake ECU 120 includes current sensors 92rl and 92rr that detect the magnitudes of currents supplied from the motor drive circuit to the motors 60rl and 60rr, and the motor that is the energization amount for each of the motors 60rl and 60rr. The current im can be monitored. Further, the parking brake ECU 120 is connected to a parking brake operation switch 93, a shift position sensor 94, a vehicle speed sensor 95, and a pedal switch 90. The parking brake operation switch 93 outputs a parking brake operation signal indicating a setting state (parking brake operation, parking brake release) of the parking brake operated by the driver. The shift position sensor 94 outputs a shift position signal indicating the set position of the shift lever operated by the driver. The vehicle speed sensor 95 outputs a sensor signal representing the vehicle speed V.

  The parking brake ECU 120 causes the parking brake to function when the parking brake operation switch 93 operated by the driver indicates the parking brake operation or when the shift lever setting position indicates the parking position (P range). Operates as follows. Hereinafter, the signals output from the parking brake operation switch 93 and the shift position sensor 94 are referred to as parking brake signals, and when the parking brake operation switch 93 operated by the driver indicates the parking brake operation, or the shift lever setting position. In the following description, it is assumed that the parking brake signal is in an on state when the parking position (P range) represents the parking position, and the parking brake signal is in an off state in other cases. The parking brake signal is a signal representing a braking request (corresponding to the first braking request of the present invention) or a braking release request (corresponding to the first braking cancellation request of the present invention).

  Next, a control process performed by the parking brake ECU 120 will be described. The parking brake ECU 120 controls the electric actuator 50rl for the left rear wheel and the electric actuator 50rr for the right rear wheel independently. The control process will be described. First, the processing when the parking brake is operated will be described. FIG. 6 shows a parking brake operation control routine executed by the parking brake ECU 120.

  When the parking brake operation control routine is activated, the parking brake ECU 120 first determines in step S11 whether or not a parking brake signal (denoted as PKB in the drawing) is turned on. When the parking brake signal is switched from the off state to the on state, that is, when a braking request is generated, the parking brake ECU 120 repeats the determination process of step S11 at a predetermined calculation cycle. Is read, and the rotation angle θ is stored as an initial rotation angle θstart.

  Subsequently, the parking brake ECU 120 applies a constant forward drive voltage to the motor 60 of the electric actuator 50 in step S13, and starts the forward drive of the motor 60. By the forward rotation of the motor 60, the electric actuator 50 pushes the shoe web 31 so that the left and right advance / retreat rods 82 move forward and the distance between them is increased. Thereby, the brake shoe 30 is expanded as the motor 60 rotates.

  Subsequently, the parking brake ECU 120 detects the motor current im detected by the current sensor 92 in step S14, and determines in step S15 whether or not the motor current im is greater than or equal to the stop set current istop. If the motor current im is less than the stop set current istop, the parking brake ECU 120 returns the process to step S14 and repeats the above process at a predetermined calculation cycle.

  In the screw feed mechanism 80, when the brake shoe 30 does not press the brake drum 10, the male screws 811 and 812 of the screw member 81 and the male screws 8211 and 8221 of the advance / retreat rods 821 and 822 do not press each other in the axial direction. . For this reason, less torque is required to rotate the screw member 81. Accordingly, in the worm gear mechanism 70, as schematically shown in FIG. 16A, the screw member 81 can be rotated without strongly pressing the teeth of the worm wheel 72 with the teeth of the worm 71. In this case, since the motor load is constant, the motor current im has a constant value during the period from the energization start time t1 to the contact start time t2, as shown in FIG.

  After the forward / backward rod 82 advances by the forward rotation of the motor 60 and the brake shoe 30 contacts the brake drum 10, the male screws 811 and 812 of the screw member 81 and the male screws 8211 and 8221 of the forward / backward rod 82 are axially moved. Will come to push each other. For this reason, the motor torque required to rotate the screw member 81 increases. Accordingly, in the worm gear mechanism 70, as shown in FIG. 16B, the teeth of the worm wheel 72 are strongly pressed in the forward rotation direction by the teeth of the worm 71, and the friction between the worm 71 and the worm wheel 72 is caused. Resistance increases. This frictional resistance increases as the force with which the brake shoe 30 presses the brake drum 10 (the amount of expansion of the brake shoe 30) increases, and increases the motor load. For this reason, the motor current im increases as the frictional resistance increases.

  When the motor current im becomes equal to or greater than the stop set current istop (S15: Yes), the parking brake ECU 120 stops the forward rotation drive of the motor 60 in step S16. The stop setting current istop is a current necessary for expanding the brake shoe 30 to a position where the parking brake functions reliably, and is determined in advance by experiments or the like and stored in the brake ECU 120. Therefore, when the forward rotation drive of the motor 60 is stopped in step S16, the parking brake functions reliably. As shown in FIG. 15, the motor current im increases from time t2 when the brake shoe 30 comes into contact with the brake drum 10, and reaches the stop setting current istop at time t3. The parking brake ECU 120 stops energization of the motor 60 at this time t3.

  Subsequently, the parking brake ECU 120 reads the rotation angle θ of the motor 60 detected by the rotation angle sensor 91 in step S17, temporarily stores the rotation angle θ as a stop rotation angle θstop, and in step S12. The difference (θstop−θstart) between the stored initial rotation angle θstart and stop rotation angle θstop is calculated as the rotation amount R required for the operation of the parking brake. Subsequently, the parking brake ECU 120 stores the rotation amount R as a return rotation amount R0 in step S18. This return rotation amount R0 is stored and held until the parking brake is released.

  Subsequently, in step S19, the parking brake ECU 120 reads the switch signal output from the pedal switch 90, and determines whether or not the switch signal is off, that is, the brake pedal 201 is not depressed. The parking brake ECU 120 waits until it is detected that the switch signal is turned off, and then advances the process to step S20. In this step S20, the parking brake ECU 120 transmits to the service brake ECU 110 a command for prohibiting the supply of hydraulic pressure to the wheel cylinder 40 of the rear wheel.

  When receiving the hydraulic pressure supply prohibition command, the service brake ECU 110 closes the rear wheel hydraulic pressure supply opening / closing valve provided in the hydraulic pressure supply circuit 200. As a result, the hydraulic pressure is not supplied from the hydraulic pressure supply circuit 200 to the wheel cylinder 40 of the rear wheel regardless of the driver's brake pedal operation. Further, since the on-off valve is closed while the brake pedal 201 is not depressed, the rear wheel wheel cylinder 40 is maintained in a state in which the piston 41 is returned to the initial position. That is, during operation of the parking brake, the rear wheel wheel cylinder 40 is maintained in a state (non-braking state) in which the brake shoe 30 cannot be expanded. Therefore, when the parking brake is released, the brake shoe 30 does not deform the brake drum 10 (increase in the drum diameter) and the lining 33 (compressive deformation, shear deformation) due to the force of pressing the brake drum 10. It has become. Although the reason for doing so will be described later, it is to properly set the standby position of the brake shoe 30 when the parking brake is released.

  Parking brake ECU120 will complete | finish a parking brake operation control routine, if the prohibition instruction | command of hydraulic pressure supply is transmitted in step S20. The parking brake operation control routine is restarted at the timing when the parking brake release control routine described later is completed.

  Next, the process of the parking brake ECU 120 when releasing the parking brake will be described. FIG. 7 shows a parking brake release control routine executed by the parking brake ECU 120. This parking brake release control routine includes a process for setting the standby position of the brake shoe 30, that is, a process for setting the clearance between the brake shoe 30 and the brake drum 10 during non-braking. The parking brake release control routine is started at the timing when the above-described parking brake operation control routine ends.

  When the parking brake release control routine is activated, the parking brake ECU 120 first determines whether or not the parking brake signal (PKB signal) is turned off in step S21. The parking brake ECU 120 repeatedly performs the determination process in step S21 at a predetermined calculation cycle. When the parking brake signal is switched from the on state to the off state, that is, when a brake release request (corresponding to the first brake release request of the present invention) is generated, the parking brake ECU 120 turns off the parking brake signal in step S22. At the time point, the stoppage maintenance time Ts in which the vehicle has been stopped is read, and it is determined whether or not the stoppage maintenance time Ts is equal to or longer than the set time T0.

  The parking brake ECU 120 executes a stoppage maintenance time measurement routine shown in FIG. 8 or FIG. 9 in parallel with the parking brake release control routine and the parking brake operation control routine. In step S22, the stoppage maintenance time measurement routine is executed. The stop maintenance time Ts at the present time measured at is read. For example, in the stoppage maintenance time measurement routine shown in FIG. 8, the parking brake ECU 120 determines whether or not the vehicle speed V detected by the vehicle speed sensor 95 in step S41 is zero, and when the vehicle speed V is zero. Increments the timer value representing the stop keeping time Ts by a value 1 (S42), and if the vehicle speed V is not zero, clears the timer value representing the stop keeping time Ts to zero (S43). The parking brake ECU 120 measures the current stoppage maintenance time Ts by repeating the stoppage maintenance time measurement routine at a predetermined short calculation cycle.

  In the stoppage maintenance time measurement routine shown in FIG. 8, the stoppage maintenance time Ts is set according to the vehicle speed V, but it can be estimated that the vehicle is maintained in the stop state when the parking brake is operating. The continuation time during which the parking brake is operating can also be set as the stop maintenance time Ts. The example is a stop maintenance time measurement routine shown in FIG. In this stop maintenance time measurement routine, the parking brake ECU 120 determines whether or not the parking brake is in operation in step S51. If the parking brake is in operation, the parking brake ECU 120 indicates a stop maintenance time Ts. The value is incremented by 1 (S52), and if the parking brake is not in operation, the timer value indicating the stop keeping time Ts is cleared to zero (S53). The parking brake ECU 120 measures the current stoppage maintenance time Ts by repeating the stoppage maintenance time measurement routine at a predetermined short calculation cycle.

  Further, as a modified example of the stoppage maintenance time measurement routine, although not shown in the figure, when the vehicle speed V is zero and the parking brake is operating, a timer value indicating the stoppage maintenance time Ts is set to a value of 1. When the vehicle speed V is not zero or the parking brake is not operating, the timer value indicating the stop keeping time Ts can be cleared to zero.

  This stop maintenance time Ts is a parameter having a correlation with the temperature of the brake drum 10 and corresponds to the drum temperature index value of the present invention. Based on this drum temperature index value, it can be determined whether or not the thermal expansion amount of the brake drum 10 is within an allowable range. While the vehicle is stopped, frictional heat is not generated between the brake drum 10 and the brake shoe 30. Therefore, it can be estimated that the longer the stop time, the closer the brake drum 10 is to a normal temperature state, and the thermal expansion amount (increase in drum diameter) of the brake drum 10 is within an allowable range. The set time T0 used in step S22 is a threshold value for determining whether or not the temperature of the brake drum 10 is a temperature that hardly affects the setting of the standby position of the brake shoe 30 described later. For example, the set temperature T0 may be set in advance as the time from the highest temperature of the brake drum 10 assumed during normal traveling to the temperature at which the thermal expansion amount falls within the allowable range. Moreover, normal temperature (for example, 20 ° C. ± 15 ° C.) may be adopted as the temperature at which the thermal expansion amount falls within the allowable range.

  When the stoppage maintaining time Ts is equal to or longer than the set time T0 (S22: Yes), the parking brake ECU 120 applies a constant reverse drive voltage to the motor 60 of the electric actuator 50 in step S23, so that the motor 60 Start reverse drive. By the reverse drive of the motor 60, the left and right advance / retreat rods 82 are retracted to draw the shoe web 31.

  While the parking brake is in operation, even if the motor 60 is not driven, the restoring force of the brake drum 10, that is, the force with which the brake drum 10 pushes back the brake shoe 30, The male screws 8211 and 8221 of the advance / retreat rod 82 are pressed against each other in the axial direction. When the motor 60 is driven in reverse from this state, in the worm gear mechanism 70, as shown in FIG. 16C, the teeth of the worm 71 strongly push the teeth of the worm wheel 72 in the reverse direction. In this case, the motor 60 rotates the worm 71 against the frictional resistance between the worm 71 and the worm wheel 72 to retract the advance / retreat rod 82.

  The frictional resistance decreases because the force with which the brake shoe 30 presses the brake drum 10 (the force with which the brake drum 10 pushes back the brake shoe 30) decreases as the advance / retreat rod 82 moves backward. As the frictional resistance decreases, the motor torque required to move the brake shoe 30 decreases, and the motor current im decreases. For example, when reverse rotation driving of the motor 60 is started at time t4 in FIG. 15, the motor current im decreases. Then, after time t5 when the brake shoe 30 is separated from the brake drum 10, the male screws 811 and 812 of the screw member 81 and the male screws 8211 and 8221 of the advance / retreat rod 82 are not pressed against each other in the axial direction. Accordingly, the frictional resistance between the worm 71 and the worm wheel 72 is constant, and the motor current im is also constant.

  When the parking brake ECU 120 starts reverse rotation driving of the motor 60, the parking brake ECU 120 detects the motor current im detected by the current sensor 92 in step S24, and calculates the change gradient Ki with respect to time of the motor current im in step S25. . The change gradient Ki represents the gradient of the motor current im from time t4 in the graph shown in FIG.

  Subsequently, in step S26, the parking brake ECU 120 determines whether or not the state in which the change gradient Ki has decreased is changed to a constant state. While the brake shoe 30 is in contact with the brake drum 10, the motor current im decreases due to a decrease in frictional resistance between the worm 71 and the worm wheel 72. While the change gradient Ki is decreasing (S26: No), the parking brake ECU 120 returns the process to step S24 and repeats the same process.

  When such a process is repeated and the change gradient Ki becomes constant as shown at time t5 in FIG. 15 (S26: Yes), the parking brake ECU 120 advances the process to step S27. The time t5 can be estimated to be the time at the moment when the brake shoe 30 is separated from the brake drum 10 (released from contact). In step S27, the parking brake ECU 120 starts reading the rotation angle θ detected by the rotation angle sensor 91, and starts measuring the rotation amount R that is an increase in the rotation angle θ thereafter. Therefore, the rotation angle θ first read in step 27 represents the estimated operation amount of the electric actuator 50 (the positions of the forward and backward rods 821 and 822) at the time when the brake shoe 30 is estimated to be separated from the brake drum 10. It also represents the estimated contact release position of the brake shoe 30. Hereinafter, the position of the brake shoe 30 specified by the operation amount of the electric actuator 50 at the time when the brake shoe 30 is estimated to be separated from the brake drum 10 is referred to as a contact release position. Subsequently, in step S28, the parking brake ECU 120 determines whether or not the rotation amount R is equal to or greater than the set rotation amount R1, and waits until the rotation amount R is equal to or greater than the set rotation amount R1.

  When the parking brake ECU 120 determines that the rotation amount R is equal to or greater than the set rotation amount R1 (S28: Yes), the reverse rotation driving of the motor 60 is stopped in step S29, and the rotation amount R is measured in step S30. Exit. The set rotation amount R1 is an amount corresponding to a set clearance between the brake shoe 30 and the brake drum 10 when the parking brake is not operated. Therefore, the brake shoe 30 is a position that is returned by the set clearance from the contact release position with reference to the contact release position where the contact with the brake drum 10 is estimated to be released (the operation amount of the first actuator of the present invention). Corresponding to the position when the predetermined amount is decreased). In this case, the brake drum 10 is not thermally expanded, and since the operation of the wheel cylinder 40 is prohibited, the drum drum is not deformed to increase in diameter, so the standby position of the brake shoe 30 is set to the lining 33. Appropriate according to the amount of wear. The processes in steps S24 to S29 are the clearance adjustment process for the brake shoe 30.

  Subsequently, in step S31, the parking brake ECU 120 reads a switch signal output from the pedal switch 90, and determines whether or not the switch signal is off, that is, the brake pedal 201 is not depressed. The parking brake ECU 120 waits until it is detected that the switch signal is turned off, and then advances the process to step S32. In step S <b> 32, the parking brake ECU 120 transmits a hydraulic pressure supply permission command to the wheel cylinder 40 of the rear wheel to the service brake ECU 110. When the service brake ECU 110 receives the hydraulic pressure supply permission command, the service brake ECU 110 opens the rear wheel hydraulic pressure supply opening / closing valve provided in the hydraulic pressure supply circuit 200. As a result, the hydraulic pressure corresponding to the driver's brake pedal operation is supplied to the wheel cylinder 40 of the rear wheel.

  Further, when the parking brake ECU 120 determines in step S22 that the vehicle stop keeping time Ts is less than the set time T0, that is, it is determined that the thermal expansion amount of the brake drum 10 may exceed the allowable range. If so, the process proceeds to step S33. In step S <b> 33, the parking brake ECU 120 applies a constant reverse drive voltage to the motor 60 of the electric actuator 50 to start reverse drive of the motor 60. By the reverse drive of the motor 60, the left and right advance / retreat rods 82 are retracted to draw the shoe web 31.

  When the parking brake ECU 120 starts the reverse rotation driving of the motor 60, the parking brake ECU 120 starts reading the rotation angle θ detected by the rotation angle sensor 91 in the subsequent step S34, and the rotation amount that is the increment of the rotation angle θ thereafter. Start measuring R. Subsequently, in step S35, the parking brake ECU 120 determines whether or not the rotation amount R is equal to or greater than the return rotation amount R0, and waits until the rotation amount R becomes equal to or greater than the set rotation amount R0. The return rotation amount R0 is the rotation amount stored in step S18 of the immediately preceding parking brake operation control routine. That is, this is the amount of rotation of the motor 60 when the parking brake is operated.

  If the parking brake ECU 120 determines that the rotation amount R is greater than or equal to the return rotation amount R0 (S35: Yes), the process proceeds to step S29, and the above-described processing is performed. Therefore, when the vehicle stop keeping time Ts is less than the set time T0, the brake shoe 30 is returned to the original position by rotating the motor 60 reversely by the amount of rotation of the motor 60 in the parking brake operation control routine. It is. In this case, even if the brake drum 10 is thermally expanded, heat is radiated more than when the parking brake is operated. For this reason, the contact between the brake shoe 30 and the brake drum 10 can be reliably released.

  When the parking brake ECU 120 transmits a hydraulic pressure supply permission command in step S32, the parking brake release control routine is terminated and the parking brake operation control routine described above is started.

According to the drum brake device of the present embodiment described above, the following operational effects are obtained.
1. When there is a possibility that the thermal expansion amount of the brake drum 10 exceeds the allowable range, the clearance adjustment (setting of the standby position) of the brake shoe 30 is prohibited. As a result, the possibility of occurrence of over-adjustment can be reduced.

  2. Based on the change gradient of the motor current im, the time point at which the contact between the brake shoe 30 and the brake drum 10 is released is estimated. Therefore, the contact release position can be estimated appropriately and easily. Further, a position where a predetermined clearance (corresponding to R1) is provided between the brake shoe 30 and the brake drum 10 with the contact release position as a reference is set as a new standby position. Therefore, the standby position can be set appropriately and easily.

  3. Since the vehicle stop keeping time Ts is used as a drum temperature index for determining whether or not the thermal expansion amount of the brake drum 10 is within the allowable range, a temperature sensor for measuring the temperature of the brake drum 10 is unnecessary, and the cost is low. Can be implemented.

  4). The standby position is set only when the parking brake is released while the vehicle is stopped, and is not set when the service brake is activated. For this reason, the possibility of occurrence of over-adjustment due to deformation of the brake drum 10 (increase in drum diameter) and deformation of the lining 33 (compression deformation, shear deformation) can be further reduced. That is, the standby position is more appropriately set.

  5. When the standby position is set during the parking brake release operation, the operation of the wheel cylinder 40 is prohibited. For this reason, the possibility of occurrence of over-adjustment due to deformation of the brake drum 10 (increase in drum diameter) and deformation of the lining 33 (compression deformation, shear deformation) can be further reduced.

  6). The drum brake 1 is provided between one end side of the pair of brake shoes 30 and is operated by a parking brake operation, and is provided between the other end side of the pair of brake shoes 30 and is operated by a brake pedal operation. A wheel cylinder 40. For this reason, the operation of the parking brake and the operation of the service brake can be appropriately performed independently. In addition, it is not necessary to set a standby position when operating the service brake, an appropriate standby position can be set, and the possibility of occurrence of over-adjustment can be further reduced.

  7). When there is a possibility that the brake drum 10 is thermally expanded during the parking brake release operation (Ts ≧ T0), the position where the brake shoe 30 is returned is the motor 60 at the time of the last parking brake operation operation. The rotation amount R0 is set. For this reason, the brake shoe 30 can be reliably returned to the original position, and the contact between the brake shoe 30 and the brake drum 10 can be released.

  8). Since the standby position is set using the first actuator 50 that operates the parking brake, a dedicated automatic adjuster is not required. For this reason, the number of parts can be reduced.

  Next, Modification 1 will be described. In the above-described embodiment, after the parking brake is activated, the hydraulic pressure is maintained so as not to be supplied to the wheel cylinder 40 of the rear wheel. However, in the first modification, the hydraulic pressure supply is not prohibited. It is a thing. FIG. 10 illustrates a parking brake operation control routine according to the first modification, and FIG. 11 illustrates a parking brake release control routine according to the first modification.

  The parking brake operation control routine (FIG. 10) according to Modification 1 is obtained by omitting the processes of steps S19 and S20 in the parking brake operation control routine (FIG. 6) of the embodiment. Therefore, the hydraulic pressure is supplied to the wheel cylinders 6 and 40 of the front and rear wheels when the brake pedal is operated regardless of whether or not the parking brake is in operation. The parking brake release control routine (FIG. 11) according to the modified example 1 adds the processing of step S221 between step S22 and step S23 in the parking brake release control routine (FIG. 7) of the embodiment. The processing of S31 and S32 is omitted.

  In the parking brake release control routine, the parking brake ECU 120 reads the switch signal output from the pedal switch 90 in step S221, and the switch signal is off, that is, whether or not the brake pedal 201 is not depressed. Determine whether. The parking brake ECU 120 waits until it is detected that the switch signal is turned off, and then proceeds to step S23. Thus, when the standby position setting process after step S23 is performed, the wheel cylinder 40 is in a state where the brake shoe 30 is not pushed out (non-braking state). For this reason, since the standby position of the brake shoe 30 is set in a state where the deformation of the brake drum 10 (increase in the drum diameter) and the deformation of the lining 33 (compression deformation, shear deformation) are not generated, the standby position is set appropriately. can do.

  Next, Modification 2 will be described. In the above-described embodiment, the output processing of the prohibition command and the permission command related to the hydraulic pressure supply of the wheel cylinder 40 of the rear wheel is incorporated in the parking brake operation control routine and the parking brake release control routine. The output processing of the prohibition command and the permission command related to the hydraulic pressure supply of the wheel cylinder 40 of the rear wheel is set in a separate routine. Accordingly, in the second modification, the parking brake operation control routine is the same as the process of the first modification (FIG. 10), and the parking brake release control routine is the steps S31 and S32 of the parking brake release control routine of the embodiment. Is omitted.

  The parking brake ECU 120 executes a hydraulic pressure command control routine shown in FIG. 12 in parallel with the parking brake operation control routine or the parking brake release control routine. The parking brake ECU 120 repeatedly executes the hydraulic pressure command control routine at a predetermined calculation cycle. When the hydraulic pressure command control routine is activated, the parking brake ECU 120 determines in step S61 whether the vehicle speed V detected by the vehicle speed sensor 95 is zero, that is, whether or not the vehicle is stopped. (S62: No), in step S65, a permission command to supply hydraulic pressure to the wheel cylinder 40 of the rear wheel is transmitted to the service brake ECU 110. On the other hand, when the vehicle speed V is zero (S61: Yes), the parking brake ECU 120 reads the switch signal output from the pedal switch 90 in step S62 and the switch signal is turned off, that is, the brake pedal 201 is depressed. It is determined whether or not the operation is not performed. When the switch signal is on, that is, when the brake pedal 201 is depressed (S62: No), the parking brake ECU 120 controls the rear wheel wheel cylinder with respect to the service brake ECU 110 in step S65 described above. A permit command for supplying hydraulic pressure to 40 is transmitted.

  On the other hand, when the switch signal is OFF (S62: Yes), the parking brake ECU 120 is operating the parking brake in step S63, that is, the brake shoe 30 is pressing the brake drum 10 by the electric actuator 50. It is determined whether or not it is in a state. When the parking brake is not in operation (S63: No), the parking brake ECU 120 transmits a permission command to supply hydraulic pressure to the wheel cylinder 40 of the rear wheel to the service brake ECU 110 in step S65. On the other hand, when the parking brake is in operation, in step S64, a command to prohibit the supply of hydraulic pressure to the wheel cylinder 40 of the rear wheel is transmitted to the service brake ECU 110.

  Accordingly, in the second modification, as in the embodiment or the first modification, when the parking brake release operation is performed, the brake drum 10 is deformed (increase in the drum diameter) and the lining 33 is deformed (compression deformation, shear deformation). ) Does not occur, the possibility of occurrence of over-adjustment can be reduced.

  Next, Modification 3 will be described. In the embodiment and the first and second modifications described above, the standby position of the brake shoe 30 is set using the rotation amount R of the motor 60. However, in the third modification, the energization time of the motor 60 is used. Thus, the standby position of the brake shoe 30 is set. FIG. 13 shows a parking brake operation control routine according to the third modification, and FIG. 14 shows a parking brake release control routine according to the third modification.

  The parking brake operation control routine (FIG. 13) according to the modified example 3 is replaced with step S12 ′ instead of step S12 of the parking brake operation control routine (FIG. 6) of the embodiment, and step S17 ′ and step S18 instead of step S17. Instead, step S18 ′ is performed, and other processes are the same as those in the embodiment.

  When the parking brake signal is turned on (S11: Yes), the parking brake ECU 120 starts time counting by the energization timer in step S12 'and starts normal rotation driving of the motor 60 in step S13. Since the process of step S12 'and the process of step S13 are performed substantially simultaneously, the energization timer measures the energization time Ti, which is the time during which the motor 60 is driven forward. When the parking brake ECU 120 confirms that the motor current im has reached the stop setting current istop (S15: Yes), the forward drive of the motor 60 is stopped (S16), and in step S17 ′, the time is stopped by the energization timer. To do. Subsequently, in step S18 ', the parking brake ECU 120 returns the energization time Ti timed by the energization timer as a return energization time Ti0, and then clears the energization time Ti to zero. This return energization time Ti0 is stored and held until the parking brake is released.

  The parking brake release control routine (FIG. 14) according to the modified example 3 is replaced with step S27 ′ instead of step S27 of the parking brake release control routine (FIG. 7) of the embodiment, and step S28 ′ and step S30 instead of step S28. Instead, Step S30 ′, Step S34 ′ are replaced with Step S34 ′, and Step S35 ′ is replaced with Step S35 ′. Other processes are the same as those in the embodiment.

  If the parking brake ECU 120 determines in step S26 that the change gradient Ki of the motor current im has changed from a decreasing state to a constant state, in step S27 ', the parking brake ECU 120 starts counting by the energization timer. Subsequently, the parking brake ECU 120 determines in step 28 ′ whether or not the energization time Ti counted by the energization timer is equal to or greater than the set energization time Ti1, and waits until the energization time Ti becomes equal to or greater than the set energization time Ti1. To do. When the energization time Ti becomes equal to or longer than the set energization time Ti1 (S28 ': Yes), the parking brake ECU 120 stops the forward drive of the motor 60 in step S29. Subsequently, in step S30 ', the parking brake ECU 120 ends the time counting by the energization timer and clears the energization time Ti to zero.

  The timing by the energization timer is started at the timing when the contact between the brake shoe 30 and the brake drum 10 is released. For this reason, since the motor load is constant, the energization time of the motor 60 and the moving distance of the brake shoe 30 have a stable and constant relationship. Therefore, the position of the brake shoe 30 can be accurately controlled by the energization time of the motor 60. The set energization time Ti1 is set to a time required for the brake shoe 30 to return from the contact release position by the set clearance with reference to the contact release position where the contact between the brake shoe 30 and the brake drum 10 is released. ing. That is, the set energization time Ti1 is set to a value corresponding to the set rotation amount R1 of the embodiment. Therefore, the standby position of the brake shoe 30 is appropriate according to the amount of wear of the lining 33.

  Further, when the parking brake ECU 120 determines in step S22 that the vehicle stop keeping time Ts is less than the set time T0, the parking brake ECU 120 starts reverse rotation driving of the motor 60 in step S33, and in the subsequent step S34 ′, the energization timer Start timing with. Subsequently, in step S35 ′, the parking brake ECU 120 determines whether or not the energization time Ti counted by the energization timer is equal to or longer than the return energization time Ti0, and waits until the energization time Ti becomes equal to or greater than the return energization time Ti0. To do. The parking brake ECU 120 reads the return energization time Ti0 stored in step S18 'of the immediately preceding parking brake operation control routine, and makes the above determination.

  If the parking brake ECU 120 determines that the energization time Ti is equal to or longer than the return energization time Ti0 (S35 ': Yes), the process proceeds to step S29 and the above-described process is performed. Therefore, when the vehicle stop keeping time Ts is less than the set time T0, the brake shoe 30 is returned to the original position by rotating the motor 60 in the reverse direction for the time when the motor 60 is energized in the parking brake operation control routine. Thereby, the contact between the brake shoe 30 and the brake drum 10 can be reliably released.

  In the third modification, the rotation amount R in the embodiment is replaced with the energization time Ti. However, the rotation amount R in the first modification can be replaced with the energization time Ti.

  The drum brake device according to the present embodiment and the modification has been described above. However, the present invention is not limited to the embodiment and the modification, and various modifications can be made without departing from the object of the present invention. .

  For example, in the present embodiment, a configuration in which the thermal expansion (temperature state) of the brake drum 10 is estimated based on the length of the stop keeping time Ts is adopted, but instead, the temperature of the brake drum 10 is directly used. In step S22, it may be determined whether or not the temperature detected by the temperature sensor is lower than the set temperature (thermal expansion determination temperature).

  Further, in the present embodiment, a configuration is used in which the time point at which the contact between the brake shoe 30 and the brake drum 10 is released is estimated based on the change gradient of the motor current im, but instead, for example, Further, a pressure sensor may be provided on the advance / retreat rods 821, 822 and the like, and the time point at which the contact between the brake shoe 30 and the brake drum 10 is released may be estimated based on the detection value detected by the pressure sensor. .

  Further, in step S22 of the present embodiment, it is determined whether or not the stop keeping time Ts is equal to or longer than the set time T0. Instead, for example, after the ignition switch is turned on, the first braking release is performed. You may make it determine whether it exists. Since it is highly possible that the brake drum 10 is cooled during the ignition switch off period, the thermal expansion amount of the brake drum 10 is within an allowable range when the first brake is released after the ignition switch is turned on. This is because it is considered that over-adjustment due to thermal expansion of the brake drum 10 is unlikely to occur.

  The drum brake of the present embodiment includes the electric actuator 50 and the wheel cylinder 40. However, the drum brake does not include the wheel cylinder 40 and the electric brake 50 is operated by the electric actuator 50, or the electric actuator 50 is commonly used. The structure which operates a brake and a parking brake may be sufficient. In this case, the electric actuator 50 controls the energization of the motor 60 of the electric actuator 50 based on the signal output from the operation amount detection sensor that detects the operation amount of the brake pedal 201, and uses the drum temperature index. The standby position of the brake shoe 30 may be set on condition that the thermal expansion amount of the brake drum 10 is determined to be within the allowable range.

  In the present embodiment, the rear wheel includes the drum brake 1 including the electric actuator 50, but the front and rear wheels may include the drum brake 1.

  Further, in this embodiment, the hydraulic wheel cylinder 40 is provided as the second actuator, but instead of the wheel cylinder 40, a pneumatic wheel cylinder or an electric actuator similar to the electric actuator 50 is provided. Also good.

  DESCRIPTION OF SYMBOLS 1 ... Drum brake, 10 ... Brake drum, 20 ... Back plate, 30 ... Brake shoe, 31 ... Shoe web, 32 ... Shoe rim, 33 ... Lining, 40 ... Wheel cylinder, 50 ... Electric actuator, 60 ... Motor, 70 ... Worm gear Mechanism: 71 ... Worm, 72 ... Worm wheel, 80 ... Feed screw mechanism, 81 ... Screw member, 82 ... Forward / backward rod, 90 ... Pedal switch, 91 ... Rotation angle sensor, 92 ... Current sensor, 93 ... Parking brake operation switch, 94 ... shift position sensor, 95 ... vehicle speed sensor, 100 ... brake ECU, 110 ... service brake ECU, 120 ... parking brake ECU, 200 ... hydraulic pressure supply circuit, 201 ... brake pedal.

Claims (8)

A first actuator that includes a motor and opens a pair of brake shoes by changing an operation amount by driving the motor, thereby pressing a brake drum with the brake shoes to brake a wheel;
The operation amount of the first actuator is increased in accordance with the first braking request, and the pair of brake shoes are expanded from the standby position to the braking position to bring the wheels into a braking state, and in accordance with the first braking release request, the first actuator A first actuator control device that reduces the operation amount of the pair of brake shoes to return the pair of brake shoes from the braking position to the standby position, thereby bringing the wheel into a non-braking state;
In a drum brake device comprising:
The first actuator control device includes:
Drum temperature index value acquisition means for acquiring a parameter having a correlation with the temperature of the brake drum as a drum temperature index value;
When the first brake release request is generated, the drum temperature index value is within an allowable range of the thermal expansion amount of the brake drum in the process in which the brake shoe is returned from the braking position to the standby position by the first actuator. When the operation amount of the first actuator decreases by a predetermined amount from the operation amount at the time when it is estimated that the contact between the brake shoe and the brake drum has been released, on the condition that Standby position update means for updating the position of the pair of brake shoes as the standby position;
Drum brake device with The drum brake device according to claim 1,
A second actuator different from the first actuator that presses the brake drum with the brake shoe to brake the wheel by expanding the pair of brake shoes;
The wheels are braked by expanding the pair of brake shoes from the updated standby position according to a second braking request, and the pair of brake shoes are returned to the updated standby position according to a second braking release request. A second actuator control device for bringing the wheel into a non-braking state by
With
The first actuator control device operates the first actuator in accordance with a braking request generated by a parking brake operation as the first braking request and a braking release request generated by the parking brake operation as the first braking release request. Control
The second actuator control device operates the second actuator in accordance with a braking request generated by a service brake operation as the second brake request and a brake release request generated by the service brake operation as the second brake release request. Control,
Drum brake device. The drum brake device according to claim 2, wherein
The first actuator control device is configured to update the standby position on condition that the brake shoe is not pressing the brake drum by the second actuator.
Drum brake device. The drum brake device according to claim 3, wherein
When the first brake release request is generated and the brake shoe presses the brake drum by the operation of the second actuator, the second actuator is controlled by the brake shoe. After waiting until the pressure on the brake drum is released, the first actuator is operated to release the pressure on the brake drum by the brake shoe.
Drum brake device. The drum brake device according to claim 3, wherein
In the state where the brake shoe presses the brake drum by the operation of the first actuator, the second actuator control device is configured to operate the brake shoe by the operation of the second actuator even if the second braking request is generated. Configured so as not to perform a pressing operation to the brake drum.
Drum brake device. In the drum brake device according to any one of claims 1 to 5,
The drum temperature index value acquisition means uses, as the drum temperature index value, a stoppage maintenance time that has been stopped when the first brake release request for releasing the braking state of the wheel by the first actuator is generated during a stop. Drum brake device to get. The drum brake device according to any one of claims 2 to 6,
The first actuator includes the motor, a worm fixed to the output shaft of the motor, a worm wheel that meshes with the worm, and a screw feed mechanism that converts a rotational operation of the worm wheel into an advance / retreat operation of an operating body And is configured to change the mutual distance on one end side of the pair of brake shoes by the forward and backward movement of the operating body,
The second actuator includes a cylinder having a piston that advances and retreats by a brake hydraulic fluid supplied by the second actuator control device, and changes a mutual interval on the other end side of the pair of brake shoes by the advance and retreat operation of the piston. Configured as
Drum brake device. The drum brake device according to any one of claims 1 to 7,
The first actuator is configured such that the smaller the force with which the brake shoe presses the brake drum, the smaller the motor torque required to move the brake shoe,
The first actuator control device is configured to maintain a constant state from a decreasing state in which the current of the motor decreases in a process in which the brake shoe is returned from the braking position to the standby position by driving the motor. Configured to estimate the time when switching to the brake shoe and the brake drum is released from contact,
Drum brake device.

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