JP4573683B2 - Brake pedal device for vehicle - Google Patents

Description

  The present invention controls a brake pedal operated by a driver's foot, a reaction force applying means for applying a reaction force to the operation of the brake pedal, and an operation of the reaction force applying means to respond to an increase in stroke speed of the brake pedal. The present invention relates to a brake pedal device for a vehicle provided with control means for increasing the reaction force.

As the stroke speed at which the driver depresses the brake pedal increases, the brake pedal stroke for the same pedal force decreases, thereby increasing the reaction force when the brake pedal is stepped on or in an emergency, thereby promoting the rise of the pedal force and braking force It is known from Patent Document 1 below that makes it possible to increase the ratio quickly.
Japanese Patent Laid-Open No. 11-157439

  Incidentally, since the stroke speed of the brake pedal generally increases in the region immediately after the brake pedal is started, the reaction force is simply increased according to the increase in the stroke speed of the brake pedal, as described in Patent Document 1 above. If it increases, there is a possibility that the feeling of operation becomes too hard in the area immediately after the brake pedal is started and the driver feels uncomfortable. In addition, since the stroke speed increases in the event of an increase in the brake pedal or in an emergency, the reaction force increases significantly, the brake pedal operation feeling becomes extremely hard, and the brake pedal is difficult to stroke, resulting in sufficient braking force. It may not be possible.

  The present invention has been made in view of the above circumstances, and an object thereof is to appropriately control the reaction force of a brake pedal so as to achieve both an operation feeling and a braking force.

In order to achieve the above object, according to the invention described in claim 1, a brake pedal operated by a driver's foot, a reaction force applying means for applying a reaction force to the operation of the brake pedal, and a reaction force applying Control means for controlling the operation of the means to increase the reaction force in response to an increase in the stroke speed of the brake pedal , the control means comprising: a rigidity reaction force determined based on the stroke of the brake pedal; constructed a reaction force is determined based on the sum of the viscous friction reaction force is calculated by multiplying the viscosity of the stroke speed of the brake pedal as the reaction force applying means generates Rutotomoni, the viscous friction as the reaction force is increased according to the increase of the stroke, it is increased in accordance with the prior SL viscosity increases of the stroke, a brake pedal apparatus for a vehicle, The control means sets a stroke threshold value for determining the additional pedal depression state based on the stroke speed and the stroke, and again exceeds the stroke threshold value after the stroke is reduced from the stroke threshold value. If, it is determined that the depression increment state, when it is determined the the tread seen increasing state, Ru reduce the viscous friction reaction force by changing the characteristics of the increase in the viscosity coefficient with respect to the increase of the stroke in the decreasing direction it Ru is proposed a brake pedal device for a vehicle according to claim.

  The reaction force applying motor 12 of the embodiment corresponds to the reaction force applying means of the present invention, and the brake ECU 26 of the embodiment corresponds to the control means of the present invention.

  According to the configuration of the first aspect, the reaction force applying means performs control to increase the reaction force of the brake pedal in accordance with an increase in the stroke speed of the brake pedal operated by the driver's foot. A reaction force applying means that determines a reaction force determined based on an addition value of a stiffness reaction force determined based on the pedal stroke and a viscous friction reaction force calculated by multiplying the stroke speed of the brake pedal by the viscosity coefficient The control means increases the viscosity coefficient according to the increase in the stroke so that the viscous friction reaction force increases as the stroke increases, so the stroke speed of the brake pedal tends to increase. In the initial stepping-in area (area where the stroke is small), while keeping the reaction force low and enhancing the operational feeling, depress the brake pedal greatly. To generate a large reaction force when they crowded can give a sense of security to the driver.

Further , the control means sets a stroke threshold value for determining an additional state of the brake pedal based on the stroke speed and the stroke, and when the stroke exceeds the stroke threshold again after decreasing from the stroke threshold, determines that the increasing state, when it is determined the depression increment state, because it reduces the viscous friction reaction force by changing the characteristics of the increase in the viscosity coefficient with respect to the increase of the stroke in the decreasing direction, the time usually sufficient Sufficient braking force can be generated by generating a reaction force and ensuring the necessary rigidity of the brake pedal, while reducing the reaction force when the pedal is stepped on and making the brake pedal stroke easily .

Hereinafter, embodiments of the present invention will be described based on examples and reference examples of the present invention shown in the attached drawings.

1 to 4 show a reference example of the present invention. FIG. 1 is a diagram showing an overall configuration of an ACC device including a brake-by-wire brake device, and FIG. 2 is a circuit configuration of a brake ECU. FIG. 3 is a block diagram, FIG. 3 is a graph showing the relationship between the brake pedal stroke and the viscosity coefficient, and FIG. 4 is a graph showing the relationship between the brake pedal stroke and the pedal effort (reaction force).

  As shown in FIG. 1, when a preceding vehicle is present, follow-up traveling control is performed to maintain a predetermined inter-vehicle distance from the preceding vehicle, and when there is no preceding vehicle, constant-speed traveling control is performed at a constant speed at a predetermined vehicle speed. The brake-by-wire type brake device connected to the ACC (adaptive cruise control) device that performs the operation includes the brake pedal 11 that is operated by the driver's foot, and the upper end of the brake pedal 11 can swing freely. A reaction force applying motor 12 and an encoder 13 serving as a braking signal output means are connected to a support shaft pivotally supported on the shaft. The brake pedal 11 is applied with a reaction force according to the stroke by the reaction force spring 14, and a reaction force of an arbitrary magnitude according to the stroke, stroke speed, or other signal by the torque generated by the reaction force application motor 12. Is granted.

  The encoder 13 outputs a signal corresponding to the operation amount of the brake pedal 11 (that is, the stroke of the brake pedal 11). The brake switch 15 detects the operation of the brake pedal 11 by the driver, and the pedaling force sensor 16 detects the pedaling force applied to the brake pedal 11.

  On the other hand, the brake actuator 19 connected to the wheel cylinders 18 provided on the front and rear wheels 17 (only one wheel is shown in FIG. 1) of the vehicle is generated by a hydraulic pump or a hydraulic cylinder driven by a motor. The brake fluid pressure is controlled to an arbitrary magnitude and supplied to the wheel cylinder 18 to brake the wheel 17. The master cylinder is connected to the brake pedal 11, and when the brake actuator 19 becomes inoperable due to power failure or control device failure, the wheel cylinder 18 is operated with the brake fluid pressure generated by the master cylinder. A fail-safe mechanism can be provided.

  The follow-up traveling ECU 20 determines the throttle based on the information on the obstacle such as the preceding vehicle detected by the radar device 21, the vehicle speed detected by the vehicle speed sensor 22, the operation signal of the ACC switch 23, and the operation signal of the set switch 24. The operation of the throttle actuator 25 that controls the opening of the valve and the operation of the brake actuator 19 are controlled.

  The brake ECU 26 connected to the following travel ECU 20 is configured to detect the stroke of the brake pedal 11 detected by the encoder 13, the operation state of the brake pedal 11 detected by the brake switch 15, and the pedaling force of the brake pedal 11 detected by the pedaling force sensor 16. Based on this, the operation of the reaction force applying motor 12 is controlled, and the operation of the brake actuator 19 is controlled via the follow-up travel ECU 20.

  As shown in FIG. 2, the brake ECU 26 includes a pedal stroke calculating means M1, a pedal speed calculating means M2, a passive reaction force estimating means M3, a stiffness reaction force calculating means M4, a viscous friction reaction force calculating means M5, an active Reaction force compensation current calculation means M6, current control means M7, and depression state determination means M8 are provided. Signals from encoder 13 are input to pedal stroke calculation means M1 and pedal speed calculation means M2, and current control means The reaction force applying motor 12 actual current is fed back to M7.

  When the driver operates the brake pedal 11, a signal from the encoder 13 is input to the pedal stroke calculating means M1 and the pedal speed calculating means M2, and the pedal stroke calculating means M1 calculates the stroke of the brake pedal 11 and also the pedal speed calculating means M2. Calculates the stroke speed of the brake pedal 11. The passive reaction force estimation means M3 estimates the passive reaction force, that is, the reaction force generated by the reaction force spring 14 based on the stroke of the brake pedal 11.

  The active reaction force is a reaction force generated by the reaction force applying motor 12, which includes a rigid reaction force that simulates a reaction force that depends on the pedal position when the brake pedal 11 is stepped on, and a step on the brake pedal 11. And a viscous friction reaction force that simulates a reaction force depending on the pedal speed. The rigidity reaction force is calculated by the rigidity reaction force calculation means M4 based on the stroke of the brake pedal 11, and the viscous friction reaction force is calculated. Is calculated by the viscous friction reaction force calculating means M5 based on the stroke and stroke speed of the brake pedal 11. At that time, the depression state determination means M8 determines the depression state of the brake pedal 11, and changes the viscous friction reaction force calculated by the viscous friction reaction force calculation means M5 based on the result.

  The active reaction force compensation current calculation means M6 subtracts the passive reaction force estimated by the passive reaction force estimation means M3 from the added value of the stiffness reaction force and the viscous friction reaction force, and the active reaction force to be generated in the reaction force applying motor 12 And the active reaction force is converted into a compensation current to be supplied to the reaction force applying motor 12. The current control means M7 performs feedback control so that the actual current flowing through the reaction force applying motor 12 matches the compensation current.

  Next, characteristics of the viscous friction reaction force calculated by the viscous friction reaction force calculation means M5 based on the determination result of the stepping state determination means M8 will be described.

Basically, the viscous friction reaction force calculated by the viscous friction reaction force calculation means M5 is:
Viscous frictional reaction force = viscosity coefficient × stroke speed of brake pedal. Conventionally, the viscosity coefficient is a constant value regardless of the stroke of the brake pedal 11 as shown by a broken line in FIG. 3, but in this reference example, the viscosity coefficient is small in a region where the stroke is small, and the viscosity coefficient is large in a region where the stroke is large. Is controlled to be large.

  In general, when the driver steps on the brake pedal 11, the stroke speed tends to be highest in a region where the stroke immediately after the start of the pedal is relatively small. However, by controlling the viscosity coefficient as described above, the driver Even when the stroke speed immediately after the brake pedal 11 starts to be depressed (see the shaded area), the viscosity coefficient is kept small and the viscous friction reaction force (= viscosity coefficient × stroke speed) is excessive. Can be prevented.

  That is, in FIG. 4, the total reaction force of the brake pedal 11 is obtained by adding the rigidity reaction force determined only by the stroke of the brake pedal 11 and the viscous friction reaction force determined by both the stroke speed and the stroke of the brake pedal 11. However, as described above, the total reaction force is kept small by reducing the viscous friction reaction force in a region where the stroke speed immediately after the driver starts depressing the brake pedal 11 (see the shaded region). It is easy to step on the brake pedal 1 at the beginning of the stroke, and the operational feeling can be enhanced. On the other hand, since the viscosity coefficient increases in the second half of the stroke, the viscous friction reaction force can be maintained at a large value even when the stroke speed decreases, and as a result, the total reaction force is maintained at a large value and the driver can feel safe. A feeling of operational feeling can be obtained.

FIGS. 5 to 8 show a first embodiment of the present invention, FIG. 5 is a flowchart of a stepping determination routine, FIG. 6 is a graph showing the relationship between the stroke of the brake pedal and the viscosity coefficient, and FIG. 7 is the brake pedal. FIG. 8 is a time chart showing an example of stepping-up control.

In the first embodiment, in addition to the reaction force control of the reference example, when the driver depresses the brake pedal 11 to brake the vehicle and then feels that the braking force is insufficient, the driver further depresses the brake pedal 11 (stepping on (When increasing), the reaction force of the brake pedal 11 is changed.

  First, a method for determining that the driver has increased the brake pedal 11 will be described based on the flowchart of FIG. 5 and the time chart of FIG. This step-up determination is executed by the step-down state determination means M8 in the block diagram of FIG.

  When the brake switch 15 is not turned on in step S1, that is, when the brake pedal 11 is not depressed, the maximum stroke speed is initially set to 0 and the stroke threshold is set to 0 in step S11. When the brake pedal 11 is depressed in step S1 and the brake switch 15 is turned on, the stroke threshold is initially set to 0, which is the initial setting value, in step S2, and the process proceeds to step S3. In step S3, since the maximum stroke speed is initially set to 0 at first, the stroke speed> the maximum stroke speed is established, and the process proceeds to step S4, where the stroke speed is replaced with the maximum stroke speed.

  In this way, the maximum stroke speed is sequentially updated and gradually increased. When the maximum stroke speed exceeds the stroke speed threshold 1 in step S5 (see point a in FIG. 8), the process proceeds to step S6. Thereafter, when the stroke speed decreases and the stroke speed falls below the stroke speed threshold value 2 smaller than the stroke speed threshold value 1 in step S6 (see point b in FIG. 8), the stroke at that time is set as the stroke threshold value in step S7. Replace (see point c in FIG. 8).

After a non-zero stroke threshold is set in step S7, when the stroke that has decreased from the stroke threshold in step S8 increases again and exceeds the stroke threshold (see point d in FIG. 8), the brake pedal 11 is stepped on. In step S9, the control flag is turned on (stepping on). On the other hand, if the stroke does not exceed the stroke threshold value in step S8, the control flag is turned off (no additional stepping) in step S10.

  When the increase of the brake pedal 11 is determined as described above, the characteristic of the viscosity coefficient with respect to the stroke is changed from the characteristic indicated by the broken line (no additional control) to the characteristic indicated by the solid line (addition control) as shown in FIG. No) is changed in the decreasing direction. As a result, as shown in FIG. 7, when the driver feels that the braking force is insufficient and the brake pedal 11 is stepped on strongly, the viscous friction reaction force rises abruptly and the brake pedal 11 is difficult to stroke. However (in the broken line), in this embodiment, the rise of the viscous friction reaction force can be moderated to facilitate the stroke of the brake pedal 11 (see the solid line).

  In this way, by preventing the reaction force from suddenly rising when the brake pedal 11 is stepped on, the brake pedal 11 is given a necessary rigidity (that is, reaction force) in the normal state, while the brake pedal 11 11 can be easily stroked to generate a sufficient braking force.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the first real施例illustrated brake device of a brake-by-wire type, but the second embodiment is an application of the present invention into conventional brake apparatus having a master cylinder.

The reaction force applying motor 12 and the encoder 13 are connected to a spindle that pivotally supports the upper end of the brake pedal 11 that is mechanically connected to a negative pressure booster 32 that operates the master cylinder 31. The encoder 13 outputs a signal corresponding to the stroke of the brake pedal 11, the brake switch 15 detects the operation of the brake pedal 11 by the driver, and the pedaling force sensor 16 detects the pedaling force applied to the brake pedal 11. A master cylinder 31 and wheel cylinders 18 provided on front, rear, left and right wheels (only one wheel is shown in the figure) are connected via a hydraulic module 33. The hydraulic module 33 is a signal from the follow-up travel ECU 20. Be controlled. That is, in the second embodiment, in place of the brake actuator 19 of the first real施例, so as to actuate the wheel cylinders 18 ... the brake hydraulic pressure master cylinder 32 has occurred.

Therefore, in this second embodiment, the pedal force applied to the brake pedal 11 operates the master cylinder 32 via the negative pressure booster 31, and the brake hydraulic pressure generated by the master cylinder 32 is supplied to the wheel cylinder 18 via the hydraulic module 33. Operate…. The wheel cylinders 18 are automatically operated by operating the hydraulic module 33 in response to a deceleration command from the following travel ECU 20 to generate brake hydraulic pressure.

Other configurations and effects of the second embodiment is the same as the first actual施例described above.

While the embodiments and reference examples of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, a vehicle including an ACC device is illustrated, but the present invention can be applied to any vehicle including a brake-by-wire brake device.

Further, in the first embodiment, when the brake pedal 11 is stepped on more, the viscosity coefficient increase characteristic with respect to the stroke increase is changed in the decreasing direction, so that the viscosity coefficient is decreased and the brake pedal 11 is easily stroked. In addition to this, even when the stroke speed of the brake pedal 11 is increased in an emergency such as collision avoidance, the viscosity coefficient can be similarly decreased to make it easier to stroke the brake pedal 11.

  This emergency determination is made by determining at least one of the stroke speed of the brake pedal 11, the stepping force increasing speed of the brake pedal 11, the increasing speed of the master cylinder hydraulic pressure, and the increasing amount of deceleration in the longitudinal direction of the vehicle, This can be performed in combination with at least one of the stroke, the depression force of the brake pedal 11, the hydraulic pressure of the master cylinder, the vehicle longitudinal deceleration, and the switching time from the accelerator pedal to the brake pedal 11.

The figure which shows the whole structure of the ACC device provided with the brake-by-wire type brake device Block diagram showing circuit configuration of brake ECU Graph showing the relationship between brake pedal stroke and viscosity coefficient A graph showing the relationship between brake pedal stroke and pedal effort (reaction force) Flowchart of additional depression determination routine according to the first embodiment Graph showing the relationship between brake pedal stroke and viscosity coefficient Graph showing the relationship between brake pedal stroke and viscous friction reaction force Time chart showing an example of stepping-up control The figure which shows the whole structure of the ACC apparatus provided with the brake device of 2nd Example.

11 Brake pedal 12 Reaction force application motor (reaction force application means)
26 Brake ECU (control means)

Claims (1)

The brake pedal (11) operated by the driver's foot, the reaction force applying means (12) for applying a reaction force to the operation of the brake pedal (11), and the operation of the reaction force applying means (12) are controlled to control the brake. Control means (26) for increasing the reaction force in response to an increase in the stroke speed of the pedal (11) ,
The control means (26) includes a rigid reaction force determined based on a stroke of the brake pedal (11) and a viscous friction reaction force calculated by multiplying the stroke speed of the brake pedal (11) by a viscosity coefficient. constructed a reaction force is determined based on the added value as the reactive force applying means (12) is generated with Rutotomoni, as the viscous friction reaction force is increased according to the increase of the stroke, before A vehicular brake pedal device that increases a viscosity coefficient according to an increase in the stroke ,
The control means (26) sets a stroke threshold value for determining an increased state of the brake pedal (11) based on the stroke speed and the stroke, and after the stroke has decreased below the stroke threshold value. When the stroke threshold is exceeded again, it is determined that the pedal is in a stepped-up state. When the stepped-up state is determined, the viscous friction is increased by changing the increase characteristic of the viscosity coefficient with respect to the increase in the stroke in a decreasing direction. vehicles of the brake pedal device you wherein Rukoto reduces reaction forces.

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