JP2009202665A - Braking force holding control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake holding control device for a vehicle capable of maintaining a stopping state of the vehicle by proper holding pressure. <P>SOLUTION: This braking pressure holding control device for the vehicle includes: an acceleration acquisition means 22 to acquire an output value of an acceleration sensor 93 to detect acceleration in the longitudinal direction of the vehicle; a first filter 23A to restrict a change in the output value of the acceleration sensor 93 in a direction equivalent to the front of the vehicle, a gear position determination means 24 to determine whether a gear position of the vehicle is a forward advancing gear or not, a conversion means 25 to convert a first acceleration filter value Af treated and output by the first filter 23A to a holding pressure PH when the gear position determined by the gear position determination means 24 is the forward advancing gear and a holding practice means 29 to practice holding of the braking pressure in accordance with the holding pressure PH. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle brake force holding control device that holds a brake force when starting on a slope.

  2. Description of the Related Art In recent years, devices for assisting braking force are known in order to prevent a vehicle from moving backward when starting on a slope. As such an apparatus, for example, an apparatus disclosed in Patent Document 1 is known.

  In the technique disclosed in Patent Document 1, the rearward movement is suppressed by applying a braking force when the backward force of the vehicle becomes larger than the forward force when starting on a slope. And the holding pressure for preventing the backward movement of the vehicle is calculated using the output value of the acceleration sensor as it is.

JP-A-7-69102

  However, depending on how the brakes are applied, such as when the vehicle suddenly stops, the vehicle may vibrate back and forth immediately after the vehicle stops. Therefore, if the holding pressure is calculated using the output value of the acceleration sensor as it is, there is a problem that the calculated holding force is not stable or becomes too small.

  Therefore, an object of the present invention is to provide a vehicle brake holding control device that can maintain a vehicle in a stopped state with an appropriate holding pressure.

  The present invention for solving the above-described problems is a vehicle brake pressure holding control device capable of executing brake pressure holding control for holding brake pressure so that the vehicle maintains a stopped state when the vehicle is stopped. An acceleration acquisition unit that acquires an output value of an acceleration sensor that detects acceleration; a first filter that limits a change in an output value of the acceleration sensor acquired by the acceleration acquisition unit in a direction corresponding to the front of the vehicle; If the gear position of the vehicle is a forward gear, and the gear position determined by the gear position determination means is a forward gear, it is processed and output by the first filter. It is characterized by comprising conversion means for converting the first acceleration filter value into holding pressure, and holding execution means for holding the brake pressure based on the holding pressure.

  According to such a vehicle brake pressure holding control device, the acceleration value output from the acceleration sensor is processed by the first filter, and the change in the direction corresponding to the front of the vehicle is limited. Is output as an acceleration filter value. When the gear position determined by the gear position determination unit is the forward gear, the first acceleration filter value is converted into the holding pressure. That is, since the holding pressure is calculated based on the first acceleration filter value obtained by filtering the acceleration, even if the output value of the acceleration sensor suddenly changes in the direction corresponding to the front, the holding pressure is slowly increased. Even if the vehicle changes and the vehicle vibrates, the holding pressure does not unnecessarily decrease. The holding pressure executing means executes holding of the brake pressure based on the holding pressure, whereby the brake pressure is held at an appropriate holding pressure, and the vehicle can be favorably maintained in the stopped state.

  The change of the acceleration value (sensor output value) to the direction corresponding to the front of the vehicle means the change of the acceleration value to the direction of acceleration such that the vehicle is pulled forward. For example, when the vehicle vibrates back and forth, the state in which the vehicle gradually leans forward in this vibration process is such that the acceleration that is pulled forward increases gradually. The value changes in the direction corresponding to the front. In the above-described configuration, in such a situation where the degree of forward turning is gradually increased (a situation where the acceleration value gradually changes forward), the change is limited, in other words, the change is reduced.

  The vehicle brake pressure holding control device includes a second filter that restricts a change in the output value of the acceleration sensor acquired by the acceleration acquisition unit in a direction corresponding to the rear of the vehicle, and the gear position determination The means is also configured to be able to determine whether or not the gear position of the vehicle is a reverse gear, and the conversion means is configured to change the first position when the gear position determined by the gear position determination means is a reverse gear. The second acceleration filter value processed and output by the second filter is converted into a holding pressure.

  According to such a configuration, the second filter limits the change of the acceleration value in the direction corresponding to the rear of the vehicle, and outputs it as the second acceleration filter value. When the gear position determined by the gear position determination means is the reverse gear, the second acceleration filter value is converted into the holding pressure. In other words, since the holding pressure is calculated based on the second acceleration filter value obtained by filtering the acceleration, even if the output value of the acceleration sensor suddenly changes in the direction corresponding to the rear, the holding pressure is slowly increased. Even if the vehicle changes and the vehicle vibrates, the holding pressure does not unnecessarily decrease. The holding pressure executing means executes holding of the brake pressure based on the holding pressure, whereby the brake pressure is held at an appropriate holding pressure, and the vehicle can be favorably maintained in the stopped state.

  Here, the change of the acceleration value (sensor output value) to the direction corresponding to the rear of the vehicle is opposite to the case of the front, and the acceleration value is such that the vehicle is pulled backward. It means a change in the direction of acceleration.

  In the vehicle brake pressure holding control device described above, a timer for measuring a stable time during which the rate of change of the output value of the acceleration sensor is less than a predetermined value, a determination is made as to whether or not the stable time is equal to or longer than a predetermined time, When it is determined as described above, it is preferable that the conversion unit includes a stable holding pressure selection unit that outputs the value of the holding pressure at the time of the determination to the holding execution unit instead of the holding pressure calculated this time.

  According to such a configuration, the timer measures the rate of change of the output value of the acceleration sensor below a predetermined value, that is, a stable time that is stable to a certain extent, and the stable holding pressure selection means has a stable time of a predetermined time. After that, the holding pressure at the time of determination is output to the holding execution means. Therefore, even if the vehicle vibrates due to a disturbance such as strong wind or ground shaking after the vehicle is stabilized, the brake pressure held by the holding execution means does not decrease, and the vehicle can be well maintained in the stopped state. .

  In each configuration described above, when the brake pressure acquisition means for acquiring the brake pressure of the vehicle, the stop determination means for determining whether or not the vehicle has stopped, and the stop determination means when the stop of the vehicle is determined Comparing the brake pressure acquired by the brake pressure acquisition means with the holding pressure calculated by the conversion means this time, a lower selection means for selecting the smaller one and outputting it to the holding execution means can be provided.

  According to such a configuration, the low selection means selects a smaller one of the brake pressure when the vehicle stops and the holding pressure calculated this time by the conversion means and outputs the selected one to the holding execution means. The brake pressure when the vehicle was stopped should have been large enough to stop the vehicle in the stopped situation, for example, in the situation where the vehicle stopped on the uphill road. Therefore, even if the holding pressure calculated by the conversion means is larger than the brake pressure at the time of stop, the stop state of the vehicle can be sufficiently maintained if the holding control is executed with the brake pressure at the time of stop. Therefore, by outputting the holding pressure calculated by the conversion means and the brake pressure at the time of stopping of the vehicle, the smaller brake pressure, the brake pressure can be made as small as possible.

  According to the present invention, even if there is any unstable element when the vehicle is stopped, the brake pressure can be maintained at an appropriate holding pressure, and the vehicle can be satisfactorily maintained in the stopped state.

[First Embodiment]
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a configuration diagram of a vehicle provided with a vehicle brake hydraulic pressure control device according to a first embodiment of the present invention, and FIG. It is.

  As shown in FIG. 1, a vehicle brake hydraulic pressure control device 100 as an example of a vehicle brake pressure holding control device is a device that appropriately controls the braking force applied to each wheel T of the vehicle CR. The vehicle brake hydraulic pressure control device 100 mainly includes a hydraulic unit 10 provided with an oil passage and various parts, and a control unit 20 for appropriately controlling various parts in the hydraulic unit 10.

  Each wheel T is provided with a wheel brake FL, RR, RL, FR, and each wheel brake FL, RR, RL, FR has a braking force by a hydraulic pressure supplied from a master cylinder M as a hydraulic pressure source. Is provided. The master cylinder M and the wheel cylinder W are each connected to the hydraulic unit 10. The brake hydraulic pressure generated in the master cylinder M in response to the depression force of the brake pedal P (the driver's braking operation) is supplied to the wheel cylinder W after being controlled by the control unit 20 and the hydraulic pressure unit 10. .

  The control unit 20 includes a pressure sensor 91 that detects a master cylinder pressure (fluid pressure in the master cylinder M), a wheel speed sensor 92 that detects a wheel speed of each wheel T, and an acceleration that detects acceleration applied to the vehicle CR. A sensor 93 and a shift position sensor 94 are connected. And this control part 20 is provided with CPU, RAM, ROM, and an input-output circuit, for example, and performs various arithmetic processing based on the input from each sensor 91-94 and the program and data memorize | stored in ROM. The control is executed. Details of the control unit 20 will be described later.

  As shown in FIG. 2, the hydraulic pressure unit 10 includes a master cylinder M that is a hydraulic pressure source that generates a brake hydraulic pressure corresponding to a pedaling force applied by the driver to the brake pedal P, and wheel brakes FR, FL, RR, RL. It is arranged between. The hydraulic unit 10 includes a pump body 10a that is a base body having an oil passage (hydraulic passage) through which brake fluid flows, a plurality of inlet valves 1 and outlet valves 2 arranged on the oil passage. The two output ports M1, M2 of the master cylinder M are connected to the inlet port 121 of the pump body 10a, and the outlet port 122 of the pump body 10a is connected to each wheel brake FR, FL, RR, RL. In normal times, the oil passage is connected from the inlet port 121 to the outlet port 122 in the pump body 10a, so that the depression force of the brake pedal P is transmitted to the wheel brakes FL, RR, RL, FR. It is like that.

  Here, the oil path starting from the output port M1 leads to the wheel brake FL on the left side of the front wheel and the wheel brake RR on the right side of the rear wheel, and the oil path starting from the output port M2 is set to the wheel brake FR on the right side of the front wheel and the left side of the rear wheel. To the wheel brake RL. Hereinafter, the oil passage starting from the output port M1 is referred to as “first system”, and the oil passage starting from the output port M2 is referred to as “second system”.

  The hydraulic unit 10 is provided with two control valve means V corresponding to each wheel brake FL, RR in the first system, and similarly corresponding to each wheel brake RL, FR in the second system. Two control valve means V are provided. The hydraulic unit 10 includes a reservoir 3, a pump 4, a damper 5, an orifice 5a, a pressure regulator (regulator) R, a suction valve 7, and a storage chamber 7a in each of the first system and the second system. ing. The hydraulic unit 10 is provided with a common motor 9 for driving the first system pump 4 and the second system pump 4. In the present embodiment, the pressure sensor 91 is provided only in the second system.

  In the following, the oil passages from the output ports M1, M2 of the master cylinder M to the pressure regulating valves R are referred to as “output hydraulic pressure passages A1,” and the oil from the first system pressure regulating valve R to the wheel brakes FL, RR. The oil passages from the road and the second system pressure regulating valve R to the wheel brakes RL and FR are respectively referred to as “wheel hydraulic pressure passage B”. In addition, an oil path from the output hydraulic pressure path A1 to the pump 4 is referred to as “suction hydraulic pressure path C”, an oil path from the pump 4 to the wheel hydraulic pressure path B is referred to as “discharge hydraulic pressure path D”, and The oil passage from the wheel fluid pressure passage B to the suction fluid pressure passage C is referred to as “open passage E”.

  The control valve means V is a valve that controls the flow of hydraulic pressure from the master cylinder M or the pump 4 side to the wheel brakes FL, RR, RL, FR side (specifically, the wheel cylinder W side). (Pressure in the wheel cylinder W) can be increased, held or decreased. Therefore, the control valve means V includes an inlet valve 1, an outlet valve 2, and a check valve 1a.

  The inlet valve 1 is a normally open electromagnetic valve provided between each wheel brake FL, RR, RL, FR and the master cylinder M, that is, in the wheel hydraulic pressure path B. The inlet valve 1 is normally open, thereby allowing brake fluid pressure to be transmitted from the master cylinder M to the wheel brakes FL, FR, RL, RR. Further, the inlet valve 1 is appropriately closed by the control unit 20 so as to cut off the brake hydraulic pressure transmitted from the brake pedal P to each wheel brake FL, FR, RL, RR.

  The outlet valve 2 is a normally closed electromagnetic valve interposed between each wheel brake FL, RR, RL, FR and each reservoir 3, that is, between the wheel hydraulic pressure path B and the release path E. Although the outlet valve 2 is normally closed, the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is released to each reservoir 3 by being appropriately opened by the control unit 20.

  The check valve 1a is connected to each inlet valve 1 in parallel. The check valve 1a is a valve that allows only the brake fluid to flow from the wheel brakes FL, FR, RL, RR to the master cylinder M, and when the input from the brake pedal P is released, Even when the valve 1 is closed, the brake fluid is allowed to flow from each wheel brake FL, FR, RL, RR side to the master cylinder M side.

  The reservoir 3 is provided in the release path E, and has a function of storing brake fluid pressure that is released when each outlet valve 2 is opened. Further, between the reservoir 3 and the pump 4, a check valve 3a that allows only the flow of brake fluid from the reservoir 3 side to the pump 4 side is interposed.

  The pump 4 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A1 and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and sucks the brake fluid stored in the reservoir 3 And has a function of discharging to the discharge hydraulic pressure path D.

  The damper 5 and the orifice 5a attenuate the pulsation of the pressure of the brake fluid discharged from the pump 4 and the pulsation generated by the operation of the pressure regulating valve R described later by the cooperative action.

  The pressure regulating valve R allows the flow of the brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B at the normal time and increases the pressure on the wheel cylinder W side by the brake hydraulic pressure generated by the pump 4. It has the function of adjusting the pressure on the discharge hydraulic pressure path D, wheel hydraulic pressure path B and control valve means V (wheel cylinder W) side to a set value or less while blocking the flow, and the switching valve 6 and the check valve 6a are It is prepared for.

  The switching valve 6 is a normally open linear solenoid valve interposed between the output hydraulic pressure path A1 leading to the master cylinder M and the wheel hydraulic pressure path B leading to each wheel brake FL, FR, RL, RR. . And when a vehicle stops on the uphill road mentioned later, the pressure in the wheel cylinder W is hold | maintained by the switching part 6 being closed by the control part 20. FIG.

  The check valve 6a is connected to each switching valve 6 in parallel. The check valve 6a is a one-way valve that allows the flow of brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B.

  The suction valve 7 is a normally closed electromagnetic valve provided in the suction fluid pressure passage C, and switches between a state in which the suction fluid pressure passage C is opened and a state in which the suction fluid pressure passage C is shut off.

  The storage chamber 7 a is provided between the pump 4 and the suction valve 7 on the suction fluid pressure path C. The storage chamber 7a stores brake fluid, and the capacity of the brake fluid stored in the suction fluid pressure path C is thereby substantially increased.

  The pressure sensor 91 detects the brake hydraulic pressure in the output hydraulic pressure path A1, and the detection result is input to the control unit 20.

  Next, details of the control unit 20 will be described. In the drawings to be referred to, FIG. 3 is a block diagram showing the configuration of the control unit, FIG. 4A is a map showing the relationship between the first acceleration filter value and the holding pressure, and FIG. These are maps showing the relationship between the second acceleration filter value and the holding pressure.

  As shown in FIG. 3, the control unit 20 includes a stop determination unit 21, an acceleration acquisition unit 22, a first filter 23A, a second filter 23B, a gear position determination unit 24, a conversion unit 25, a holding execution unit 29, and a storage. A device 31 is provided.

  The stop determination means 21 has a function of acquiring wheel speed information from the wheel speed sensor 92 and determining whether or not the vehicle has stopped based on the wheel speed. When the stop is determined, a signal indicating that the vehicle has stopped is output to the conversion means 25 and the holding execution means 29.

The acceleration acquisition means 22 is means for acquiring acceleration information from the acceleration sensor 93 in a timely manner. The acquired acceleration value (hereinafter simply referred to as “acceleration G _n ”) is output to the first filter 23A and the second filter 23B. Further, the acquired acceleration G _n is stored in the storage device 31 as appropriate.
In the present embodiment, the acceleration at which the vehicle CR is pulled backward, that is, the acceleration that occurs when the vehicle CR advances and accelerates or stops on an uphill is positive, and the vehicle is The acceleration that is pulled forward, that is, the acceleration that occurs when the vehicle CR moves backward and accelerates or stops on a downhill is negative. However, this positive / negative relationship may be set in reverse.
In the present specification and drawings, the subscript n indicates the current calculated value or acquired value, and the subscript n-1 indicates the previous calculated value or acquired value.

The first filter 23A acquires the acceleration G _n from the acceleration acquisition means 22, performs a filter process so that the acceleration G _n limits the change in the direction corresponding to the front of the vehicle, and the first acceleration filter value Af. _It has a function of outputting _n to the conversion means 25. In the present embodiment, specifically, the filtering process is performed so that the acceleration _Gn is not easily changed to a small value.

The second filter 23B acquires the acceleration G _n from the acceleration acquisition means 22, performs a filter process so that the acceleration G _n limits a change in the direction corresponding to the rear of the vehicle, and performs the second acceleration filter value Bf. _It has a function of outputting _n to the conversion means 25. In the present embodiment, specifically, the filtering process is performed so that the acceleration _Gn is not easily changed to a large value.

An example of filter processing will be described in more detail. In the present embodiment, when the vehicle CR stops on a slope, positive or negative acceleration is input to the first filter 23A and the second filter 23B. The first filter 23A is for preventing the holding pressure from being unnecessarily lowered until the vehicle CR stops on an uphill, moves forward and starts. The acceleration filter value Af _{n−1 of 1} is compared with the acceleration G _n calculated this time. When towards the current acceleration G _n is small, because it tends to vary in the direction acceleration G _n is small, the first of this was filtered to hardly changed in a direction acceleration G _n is small An acceleration filter value Af _n is determined. For example, when the difference between the previous first acceleration filter value Af _n−1 and the current acceleration G _n is larger than a predetermined constant C1, the constant C1 is calculated from the previous first acceleration filter value Af _n−1. outputs a value obtained by subtracting the first acceleration filter value Af _n of the time, if the difference between the current acceleration G _n first previous 1 between the acceleration filter value Af _n-1 is not greater than the constant C1 is now and it outputs the acceleration _{G n} as a first acceleration filter value Af _n of the time. The first acceleration filter value Af _n processed and output by the first filter 23A is stored in the storage device 31 as appropriate.

The second filter 23B is for preventing the holding pressure from being unnecessarily lowered until the vehicle CR stops on a downhill, starts moving backward, and starts with the first filter 23A. It functions in the same manner as the first filter 23A except that the direction of magnitude is reversed. That is, the second filter 23B compares the previously calculated second acceleration filter value Bf _n−1 with the acceleration G _n calculated this time. Then, when the direction of the current acceleration G _n large, acceleration since G _n tends to vary to a large direction, acceleration G _n is a second of this filtering as difficult changes in the large direction An acceleration filter value Bf _n is determined. For example, when the difference between the current acceleration G _n and the previous second acceleration filter value Bf _n−1 is larger than a predetermined constant C1, the previous second acceleration filter value Bf _{n−1 is set} to the constant C1. It outputs a value obtained by adding a second acceleration filter value Bf _n of this, when the difference between the acceleration filter value Bf _n-1 of the second current acceleration G _n and the previous is not greater than the constant C1 is The current acceleration G _n is output as the current second acceleration filter value Bf _n . The second acceleration filter value Bf _n processed and output by the second filter 23B is stored in the storage device 31 as appropriate.

  Note that the filtering method shown here is only an example, and other filters can be used as long as the first acceleration filter value Af is less likely to decrease and the second acceleration filter value Bf is less likely to increase. A processing method may be adopted.

  The gear position determination means 24 is a means for receiving a gear position (shift position) signal from the shift position sensor 94, determining whether the gear is a forward gear or a reverse gear, and outputting it to the conversion means 25. For example, when an automatic transmission is mounted on the vehicle CR, if the gear position acquired by the shift position sensor 94 is at a position where the vehicle CR moves forward, such as L (low), 2ND, and D (drive). It is determined that it is a forward gear, and if it is in the R (reverse) position, it is determined that it is a reverse gear.

The conversion means 25 should be held by the holding execution means 29 based on the first acceleration filter value Af input from the first filter 23A or the second acceleration filter value Bf input from the second filter 23B. It has a function of obtaining a holding pressure PH that is a brake pressure and outputting it to the holding execution means 29. Specifically, the conversion unit 25 determines which value of the first acceleration filter value Af and the second acceleration filter value Bf to use based on the determination result of the gear position determination unit 24. When the gear position determined by the gear position determination unit 24 is the forward gear, the conversion unit 25 converts the first acceleration filter value Af processed and output by the first filter 23A into the holding pressure PH. When the gear position determined by the gear position determination unit 24 is the reverse gear, the second acceleration filter value Bf processed and output by the second filter 23B is converted into the holding pressure PH. When converting the first acceleration filter value Af or the second acceleration filter value Bf into the holding pressure PH, for example, the storage device 31 stores the first acceleration filter value Af and the first acceleration filter value Af as shown in FIG. The relationship between the pressure PH and the relationship between the second acceleration filter value Bf and the holding pressure PH as shown in FIG. 4B are stored as a map. The first acceleration filter value Af _n or the second acceleration filter value Bf _n may be converted into the current holding pressure PH. The conversion from the first acceleration filter value Af or the second acceleration filter value Bf to the holding pressure PH is not based on such a map. For example, a calculation formula is stored in the storage device 31, and the calculation formula is calculated. May be used.

  The holding execution means 29 executes holding of the brake pressure based on the inputted holding pressure PH. That is, the switching valve 6 has a function of flowing a current corresponding to the holding pressure PH. With this holding operation, the brake pressure of each wheel brake FL, RR, RL, FR is held at the holding pressure PH.

  Next, the operation of the vehicle brake hydraulic pressure control device 100 will be described with reference to FIGS. In the drawings to be referred to, FIG. 5 is a flowchart showing the entire processing of brake pressure holding control in the first embodiment, FIG. 6 is a flowchart showing filter processing, and FIG. 7 is a brake pressure in the first embodiment. FIG. 8 is a time chart for explaining the holding control, and FIG. 8 is a time chart for explaining the brake pressure holding control in the case of reverse. The flow shown in FIG. 5 is repeatedly performed after the vehicle CR starts braking until the driver depresses the accelerator pedal until the condition for releasing the holding control is satisfied. 7 and 8, in the bottom graph, the master cylinder pressure and the wheel cylinder pressure are shown superimposed on the same graph, and the change in the indicated pressure and the change in the wheel cylinder pressure in the case of the prior art are also superimposed. Show.

As shown in FIG. 5, the control unit 20 acquires the acceleration _Gn from the acceleration sensor 93 by the acceleration acquisition means 22, and outputs the acceleration _Gn to the first filter 23A and the second filter 23B (S110). The first filter 23A and the second filter 23B perform filter processing (S200) on the acquired acceleration _Gn . As shown in FIG. 6, in the filter process, the first filter 23A reads the first acceleration filter value Af _n−1 obtained by the previous filter process, and the difference from the current acceleration G _n is a constant C1. It is determined whether it is larger (S201). When Af _n-1 −G _n is larger than C1 (S201, Yes), the first filter 23A sets the previous first acceleration filter value Af _n to the first acceleration filter value Af _{n of this time.} A value obtained by subtracting the constant C1 from _-1 is substituted (S202). This constant C1 is a positive value smaller than Af _n−1 −G _n when it is determined Yes in step S202, and the first acceleration of this time is calculated from the previous first acceleration filter value Af _n−1. It is set to limit reduce a change amount of the filter value Af _n. On the other hand, when Af _n-1 -G _n is not larger than C1 (S201, No), the first filter 23A uses the current acceleration G _{n as it} is as the current first acceleration filter value Af _n. Substitute (S203).

Next, the second filter 23B reads the second acceleration filter value Bf _n−1 obtained by the previous filtering process, and determines whether or not the difference from the current acceleration G _n is greater than a constant C1 ( S204). When G _n −Bf _n−1 is larger than C1 (S204, Yes), the second filter 23B sets the current second acceleration filter value Bf _n to the previous second acceleration filter value Bf _n. A value obtained by adding a constant C1 to _-1 is substituted (S205). The constant C1 is a positive value smaller than G _n −Bf _n−1 when determined to be Yes in step S204, and the second acceleration of this time is calculated from the previous second acceleration filter value Bf _n−1. It is set to limit the amount of change to the filter value Bf _n small. On the other hand, when G _n −Bf _n−1 is not larger than C1 (S204, No), the second filter 23B uses the current acceleration G _{n as it} is as the current second acceleration filter value Bf _n. Substitute (S206).

Returning to FIG. 5, the stop determination means 21 acquires the wheel speed V _n from the wheel speed sensor 92, determines the stop of the vehicle CR, and determines that the vehicle is not stopped (No in S _< b _> 120). If it is determined that the vehicle is stopped without repeating the process from step S110 (S120, Yes), a stop determination is output to the conversion unit 25 and the holding execution unit 29.

  On the other hand, the gear position determination means 24 receives the gear position from the shift position sensor 94, determines whether the current gear position is the forward gear or the reverse gear, and outputs it to the conversion means 25.

  If the gear position determined by the gear position determination unit 24 is the forward gear (S130, Yes), the conversion unit 25 converts the first acceleration filter value Af into the holding pressure PH (S150). On the other hand, if the gear position determined by the gear position determination means 24 is not the forward gear (S130, No) and the reverse gear (S140, Yes), the second acceleration filter value Bf is converted into the holding pressure PH (S160). ). Then, the conversion unit 25 outputs the holding pressure PH to the holding execution unit 29. If the gear position is neither the forward gear nor the reverse gear (S140, No), the process returns to step S110 and the process is repeated.

  The holding execution unit 29 executes the holding of the wheel cylinder pressure based on the holding pressure PH input from the conversion unit 25 under the condition in which the stop determination unit 21 determines the stop (S170). Specifically, a current corresponding to the holding pressure PH is passed through the switching valve 6. And the control part 20 returns to step S110 and repeats a process until the accelerator pedal is stepped on and the conditions for cancellation | release of holding | maintenance control are satisfy | filled. A specific example of this condition is, for example, a case where the driver's request for engine torque estimated from the accelerator opening is equal to or greater than a predetermined value, and the control unit 20 performs a start determination when this condition is satisfied. Release the holding control. With the above process, the hydraulic pressure in the wheel hydraulic pressure path B is adjusted by the switching valve 6 while the vehicle CR is stopped, and the pressure in the wheel cylinder W is maintained at a desired value.

  When the processing as described above is performed, the vehicle CR behaves as shown in FIG. 7, for example. As shown in FIG. 7, the vehicle CR starts braking at time t1 while traveling uphill, and suddenly stops at time t2, for example. At this time, the vehicle CR vibrates backwards and forwards at times t2 to t3 in response to the forward braking due to sudden braking (see acceleration graph). As shown in the change in the master cylinder pressure, if the driver releases the brake pedal P immediately after the sudden stop, the brake pressure is maintained based on the acceleration in the prior art. As indicated by a thin broken line, after the indicated pressure once becomes near zero (so far, the indicated pressure is the same as the wheel cylinder pressure indicated by the thin solid line), the pressure corresponding to the acceleration is again indicated. However, once the command pressure is set to 0 and the master cylinder pressure becomes 0, the pressure cannot be increased again (unless separately pressurized), and therefore the wheel cylinder pressure cannot be increased to a desired value. Also, if it is attempted to increase the wheel cylinder pressure to a desired value by separately pressurizing with a pump or the like, the control time becomes long, and as a result, the operation noise caused by operating the pump will be long. There is.

On the other hand, in the vehicle brake hydraulic pressure control apparatus 100 of the present embodiment, the acceleration _Gn is not used as it is for maintaining the brake pressure, but the first filter 23A is used in the vehicle CR that is going to start moving uphill. Thus, the filter processing is performed so that the acceleration _Gn is unlikely to change in a small direction (see times t2 to t4 in the graph of the first acceleration filter value). Then, since the holding pressure PH is determined based on the filtered first acceleration filter value Af _n and holding is executed based on the holding pressure PH, the wheel cylinder pressure also decreases due to vibrations before and after the vehicle CR. The pressure gradually changes toward an appropriate holding pressure (see times t3 to t4 in the wheel cylinder pressure graph).

Further, when the vehicle CR is going to start by going backward on a downhill, the second filter 23B performs a filtering process so that the acceleration _Gn is unlikely to change in a large direction (the acceleration filter shown in FIG. 8). (See times t2 to t4 in the value graph). Then, based on the second acceleration filter value Bf _n that filter determines the holding pressure PH, since executes holding based on the holding pressure PH, the wheel cylinder pressure is lowered by vibrations of the front and rear of the vehicle CR However, the pressure gradually changes toward an appropriate holding pressure (see times t3 to t4 in the wheel cylinder pressure graph shown in FIG. 8).

  When the control unit 20 releases the holding control, the wheel cylinder pressure starts to decrease, and the vehicle CR starts when the driving force of the engine becomes larger than the force for stopping the vehicle CR due to the wheel cylinder pressure. Will do.

  As described above, according to the vehicle brake hydraulic pressure control apparatus 100 of the present embodiment, even if the vehicle CR vibrates back and forth due to a sudden stop or the like, the holding pressure PH to be indicated does not suddenly decrease. The brake pressure (wheel cylinder pressure) is held at an appropriate holding pressure, and the holding control can be realized satisfactorily.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted as appropriate, and different parts will be mainly described. FIG. 9 is a block diagram of a control unit of the vehicle brake hydraulic pressure control device according to the second embodiment. FIG. 10 is an operation of the vehicle brake hydraulic pressure control device according to the second embodiment. FIG. 11 is a flowchart of the stable holding selection process, and FIG. 12 is a time chart for explaining the brake pressure holding control of the second embodiment.

  As shown in FIG. 9, the control unit 20 </ b> A of the second embodiment further includes a timer TMR and a stable holding pressure selection unit 26 with respect to the control unit 20 of the first embodiment.

  The timer TMR has a function of measuring a stable time TS in which the rate of change of the output value of the acceleration sensor 93 is less than a predetermined value. The stable time TS measured by the timer TMR is output to the stable holding pressure selection means 26. An example of the specific process will be described later.

  The stable holding pressure selection means 26 determines whether or not the stable time TS is equal to or longer than a predetermined time. If it is determined that the stable time TS is equal to or longer than the predetermined time, the conversion means 25 replaces the holding pressure PH calculated this time and It has a function of outputting the value of the holding pressure PH1 to the holding execution means 29 as the holding pressure PH.

  The processing of the control unit 20A will be described with reference to FIG. Note that f1 is a flag indicating whether or not the value when the holding pressure PH is stabilized is determined, and before entering the holding control (for example, when the vehicle moves or after the accelerator pedal is stepped on last time). The initial value is reset to 0.

First, as in the first embodiment, the acceleration _Gn is acquired from the acceleration sensor 93 by the acceleration acquisition unit 22 (S110) and stored in the storage device 31 (S111). Then, the rate of change RA of the acceleration _Gn is calculated by the timer TMR (S112). For example, the change rate RA can be obtained as an absolute value of a difference between the current acceleration G _n and the previous acceleration G _n−1 . Note that this value may be divided by a predetermined time.

The timer TMR compares the rate of change RA with a predetermined value RAth, and if the rate of change RA is less than the predetermined value RAth (S113, Yes), the change in the acceleration _Gn is small and the vehicle CR is stabilized. The stable time TS is counted up (S114). On the other hand, if the rate of change RA is equal to or greater than the predetermined value RAth (S113, No), the vehicle CR is considered unstable, so the stabilization time TS is reset to 0 (S115).

Next, as in the first embodiment, the first filter 23A and the second filter 23B perform the filtering process of the acceleration _Gn (S200), and the stop determination means 21 determines the stop of the vehicle CR (S130). . When the vehicle CR is stopped (S130, Yes), the conversion means 25 sets the holding pressure PH based on the first acceleration filter value Af or the second acceleration filter value Bf, as in the first embodiment. Calculate (S500: same as steps S130 to S160 in FIG. 5). Then, the stable holding pressure selection means 26 performs a stable holding pressure selection process (S300).

  In the stable holding pressure selection process, as shown in FIG. 11, it is first determined whether or not the flag f1 is 1. If f1 is not 1 (S301, No), the vehicle CR is still stable. Therefore, it is determined whether or not the stable time TS is equal to or longer than the predetermined time TSth (S302). If the stabilization time TS is less than the predetermined time (S302, No), the process is terminated as it is because the vehicle CR is not stable at this time. On the other hand, when the stable time TS is equal to or longer than the predetermined time TSth (S302, Yes), it means that the stable time TS has become equal to or longer than the predetermined time TSth for the first time, so the current holding pressure PH is set as the stable holding pressure PH1. It memorize | stores in the memory | storage device 31 (S303). Then, the flag f1 is set to 1 (S304). Then, in both the case where f1 is 1 in step S301 (S301, Yes) and the case where step S304 is processed, the vehicle CR has already been stabilized, so the storage device 31 is used as the current holding pressure PH. Is substituted with the value of the holding pressure PH1 at the time of stabilization. By these processes, after the vehicle CR is once stabilized, the stable holding pressure PH1 is output to the holding execution means 29 as the holding pressure PH.

  Then, similarly to the first embodiment, holding of the brake pressure is executed under the condition that the vehicle CR is stopped (S170).

  According to such processing, as shown in FIG. 12, even after the time t5, that is, after the vehicle CR has stabilized once, even if it vibrates back and forth due to a disturbance such as strong wind or ground shaking (acceleration time). After the stabilization time TS measured by the timer TMR becomes equal to or greater than the predetermined time TSth, the wheel cylinder pressure is maintained at a constant holding pressure PH1 without being affected by the fluctuation of the first acceleration filter value Af. Is retained. Therefore, according to the vehicle brake hydraulic pressure control apparatus 100 of the present embodiment, even if a disturbance such as strong wind or ground shaking occurs after the vehicle CR is stabilized, the vehicle CR brake is satisfactorily affected without being affected by the disturbance. The pressure can be maintained.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, the same parts as those in the second embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate, and different parts will be mainly described. FIG. 13 is a block diagram of the control unit of the vehicle brake hydraulic pressure control device according to the third embodiment. FIG. 14 is an operation of the vehicle brake hydraulic pressure control device according to the third embodiment. FIG. 15 is a flowchart of the process of storing the master cylinder pressure when the vehicle is stopped, and FIG. 16 is a time chart for explaining the brake pressure holding control of the third embodiment.

  As shown in FIG. 13, the control unit 20B of the third embodiment further includes a brake pressure acquisition unit 27 and a low selection unit 28 compared to the control unit 20A of the second embodiment.

  The brake pressure acquisition means 27 is a means for acquiring a brake pressure (wheel cylinder pressure) when the vehicle is stopped. In the present embodiment, the brake pressure at the time of stopping is the same as the master cylinder pressure, so the brake pressure acquisition unit 27 acquires the measurement value of the pressure sensor 91.

  The low selection means 28 compares the master cylinder pressure PM1 acquired by the brake pressure acquisition means when the stop determination means 21 determines the stop of the vehicle CR with the holding pressure PH calculated by the conversion means 25 this time, and is small. This is a means for selecting a method and outputting it to the holding execution means 29. In the present embodiment, the stable holding pressure selection means 26 selects one of the holding pressure PH calculated by the conversion means 25 and the stable holding pressure PH1 of the vehicle CR. The holding pressure PH output by the selection means 26 is compared with the master cylinder pressure PM1 when the vehicle is stopped.

The processing of the control unit 20B will be described with reference to FIG. In FIG. 14, steps S <b> 110 to S <b> 300 are the same as those in the second embodiment, and a description thereof will be omitted. In addition, f2 is a flag indicating whether or not the master cylinder pressure at the time of stopping is stored, and together with f1 before entering the holding control (for example, when the vehicle moves or after the accelerator pedal is stepped on last time). The initial value is reset to zero.
In step S <b> 121, the brake pressure acquisition unit 27 acquires the master cylinder pressure PM from the pressure sensor 91. The stop determination unit 21 acquires the wheel speed _{V n} from the wheel speed sensor 92 (S122).

Next, the process (S400) which selects the lower one among master cylinder pressure PM1 at the time of a stop and holding pressure PH is performed.
As shown in FIG. 15, the stop determination means 21 determines stop based on whether or not the wheel speed V _n is smaller than a predetermined value V0, and if V _n <V0 (not stopped) (S401, No). The process is terminated. On the other hand, when V _n <V0 (stops) (S401, Yes), it is determined whether or not the flag f2 is 1 (S402). If f2 is 1 (S402, Yes), since the master cylinder pressure PM1 at the time of stopping has already been stored, the process proceeds to step S405. On the other hand, if f2 is not 1 (S402, No), the low select means 28 stores the current master cylinder pressure PM in the storage device 31 as the master cylinder pressure PM1 when the vehicle is stopped (S403), and substitutes 1 for f2. (S404), the process proceeds to step S405.

  In step S405, the low selection unit 28 determines whether or not the holding pressure PH input from the stable holding pressure selection unit 26 is larger than the master cylinder pressure PM1 when the vehicle is stopped, and if it is determined to be large (S405, Yes). Then, the holding pressure PH is replaced with the master cylinder pressure PM1 at the time of stopping stored in the storage device 31 (S406) and output to the holding execution means 29. On the other hand, if it is determined that the holding pressure PH input from the stable holding pressure selection means 26 is not greater than the master cylinder pressure PM1 when the vehicle is stopped (S405, No), the input is input from the stable holding pressure selection means 26. The holding pressure PH is output to the holding execution means 29 as it is.

  Then, returning to FIG. 14, after that, holding of the brake pressure is executed under the condition that the vehicle CR is stopped in the same manner as in the first embodiment (S170).

According to such a process, as shown in FIG. 16, between the times t2 and t6, the holding pressure PH based on the inclination angle, that is, the holding pressure PH based on the first acceleration filter value Af becomes the master cylinder pressure. Even if it is larger, the master cylinder pressure PM1 at the time of stopping, that is, at the time t2, is preferentially selected, and the holding pressure PH is maintained at the pressure PM1 after the time t2.
Thus, even if the master cylinder pressure (brake pressure) PM1 at the time of stopping is selected as the holding pressure PH, it is clear that the vehicle CR can be stopped on the uphill road, so the holding based on the first acceleration filter value Af. A holding pressure PH (PM1) smaller than the pressure PH is used, and the brake pressure can be made as small as possible. For this reason, the brake pressure can be quickly reduced to 0 at the time of start, and the catch at the time of start can be prevented or reduced. That is, the moment of starting is a state in which the driving force of the engine is transmitted to the wheels to some extent as described above. At the same time, the wheel T is being stopped by the holding control, but this brake pressure quickly becomes zero. Thus, a smooth start can be realized. Further, reducing the holding brake pressure as much as possible reduces the current flowing through the switching valve 6, so that the coil of the switching valve 6 and the load of the control unit 20 can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be used in various forms as exemplified below.
Although only the brake pressure holding control when the vehicle is stopped has been described in the above embodiment, the vehicle brake hydraulic pressure control device 100 may be configured to perform ABS control, VSA control, or the like. Of course, it may be a device capable of only holding the wheel cylinder pressure without providing other functions such as ABS control.

  In the above-described embodiment, the holding control of the brake pressure on the uphill road is exemplified, but the present invention can be similarly applied to the holding control on the flat road.

  In the above embodiment, the same constant C1 is used as the value for limiting the change in the acceleration filter values Af and Bf in the first filter 23A and the second filter 23B. The value for limiting the change and the value for limiting the change in the acceleration filter value Bf in the second filter 23B may be different values.

1 is a configuration diagram of a vehicle including a vehicle brake hydraulic pressure control device according to a first embodiment of the present invention. It is a block diagram which shows the structure of the brake fluid pressure control apparatus for vehicles. It is a block diagram which shows the structure of a control part. (A) is a map showing the relationship between the first acceleration filter value and the holding pressure, and (b) is a map showing the relationship between the second acceleration filter value and the holding pressure. It is a flowchart which shows the whole process of the brake pressure holding | maintenance control in 1st Embodiment. It is a flowchart which shows a filter process. It is a time chart explaining brake pressure maintenance control of a 1st embodiment. It is a time chart explaining brake pressure maintenance control in the case of reverse. It is a block diagram of the control part of the brake fluid pressure control device for vehicles concerning a 2nd embodiment. It is a whole flowchart which shows operation | movement of the brake fluid pressure control apparatus for vehicles which concerns on 2nd Embodiment. It is a flowchart of the holding selection process at the time of stability. It is a time chart explaining brake pressure maintenance control of a 2nd embodiment. It is a block diagram of the control part of the brake fluid pressure control device for vehicles concerning a 3rd embodiment. It is a whole flowchart which shows operation | movement of the brake fluid pressure control apparatus for vehicles which concerns on 3rd Embodiment. It is a flowchart of the memory | storage process of the master cylinder pressure at the time of a stop. It is a time chart explaining brake pressure maintenance control of a 3rd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inlet valve 2 Outlet valve 6 Switching valve 10 Hydraulic unit 20 Control part 21 Stop determination means 22 Acceleration acquisition means 23A 1st filter 23B 2nd filter 24 Gear position determination means 25 Conversion means 26 Stable holding pressure selection means 27 Brake pressure acquisition means 28 Low selection means 29 Holding execution means 31 Storage device 91 Pressure sensor 92 Wheel speed sensor 93 Acceleration sensor 94 Shift position sensor 100 Brake fluid pressure control device for vehicle CR Vehicle M Master cylinder P Brake pedal R Pressure regulating valve T Wheel TMR Timer W Wheel cylinder

Claims (4)

A vehicle brake pressure holding control device capable of executing a brake pressure holding control for holding a brake pressure in order to maintain the vehicle in a stopped state when the vehicle is stopped,
Acceleration acquiring means for acquiring an output value of an acceleration sensor for detecting acceleration in the longitudinal direction of the vehicle;
A first filter that limits a change in an output value of the acceleration sensor acquired by the acceleration acquisition means to a direction corresponding to the front of the vehicle;
Gear position determination means for determining whether the gear position of the vehicle is a forward gear;
When the gear position determined by the gear position determination means is a forward gear, conversion means for converting the first acceleration filter value processed and output by the first filter into holding pressure;
A vehicle brake pressure holding control device comprising: holding execution means for holding the brake pressure based on the holding pressure. A second filter for limiting a change in an output value of the acceleration sensor acquired by the acceleration acquisition means to a direction corresponding to the rear of the vehicle;
The gear position determination means is configured to be able to determine whether the gear position of the vehicle is a reverse gear,
The conversion means converts the second acceleration filter value processed and output by the second filter into a holding pressure when the gear position determined by the gear position determination means is a reverse gear. The vehicular brake pressure holding control device according to claim 1, A timer for measuring a stable time during which the rate of change of the output value of the acceleration sensor is less than a predetermined value;
If it is determined whether or not the stable time is equal to or longer than a predetermined time, and it is determined that the stable time is equal to or longer than the predetermined time, the conversion unit replaces the holding pressure calculated this time with the value of the holding pressure at the time of the determination in the holding execution unit The vehicular brake pressure holding control device according to claim 1, further comprising a stable holding pressure selection means for outputting. Brake pressure acquisition means for acquiring the brake pressure of the vehicle;
Stop determination means for determining whether or not the vehicle has stopped;
The brake pressure acquired by the brake pressure acquisition unit when the stop determination unit determines stop of the vehicle and the holding pressure calculated this time by the conversion unit are selected, the smaller one is selected, and the holding execution is performed The vehicle brake pressure holding control device according to any one of claims 1 to 3, further comprising a low-select means for outputting to the means.

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