JP5472646B2 - Braking force control device - Google Patents

Description

  The present invention relates to a braking force control device that controls a braking force of a vehicle.

  The vehicle generates a yaw moment in the turning direction in accordance with the steering operation. When it is determined that the yaw moment is excessive, a technique for reducing the yaw moment by causing the yaw moment in the reverse direction to act on the vehicle is known. For example, a technique for controlling a braking force based on a master cylinder pressure generated by an operation of a brake pedal detected using a hydraulic pressure sensor has been disclosed (see, for example, Patent Document 1).

JP 2001-97195 A

  In patent document 1, in order to control braking force, the sensor which detects the pressure of a master cylinder is required. However, the sensor that detects the pressure of the master cylinder may be erroneously detected or may fail as with other sensors.

  The present invention has been made in view of the above problems, and one of its purposes is to provide a braking force control device that does not require a master cylinder pressure sensor.

  In order to solve the above-described problems, a braking force control device according to the present invention includes a master cylinder that generates a pressure in a fluid by operating a brake pedal, a braking device that generates a braking force by the pressure of the fluid, and the master cylinder. And a piping connecting the braking device, a first solenoid valve operated to cut off the flow of the fluid in the piping, and operated to maintain the pressure of the fluid flowing to the braking device A second solenoid valve, and a third solenoid valve operated to reduce the pressure of the fluid flowing through the braking device, the first solenoid valve being provided to control the first solenoid valve By controlling the difference between the differential pressure command amount and the second differential pressure command amount given to control the second solenoid valve to a predetermined value, and opening the third solenoid valve for a predetermined time. Controlling braking force And features.

  According to the present invention, the pressure of the fluid flowing through the first solenoid valve and the pressure of the fluid flowing from the second solenoid valve are adjusted, and the third solenoid valve is opened for a predetermined time to flow into the braking device. Control fluid pressure. As a result, the braking force can be controlled without requiring a master cylinder pressure sensor.

1 is a diagram illustrating an example of a vehicle to which a braking force control device according to an embodiment of the present invention is applied. It is a figure which shows the structure of the control system of the braking force control apparatus concerning embodiment of this invention. It is a figure which shows the structure of the solenoid valve operated so that the flow of the fluid in the piping which connects the master cylinder and brake device concerning embodiment of this invention may be interrupted | blocked. It is a figure which shows the structure of the solenoid valve operated so that the hydraulic pressure of the wheel cylinder concerning embodiment of this invention may be hold | maintained. It is a figure which shows the structure of the solenoid valve operated so that the hydraulic pressure of the wheel cylinder concerning embodiment of this invention may be pressure-reduced. It is a figure which shows the control flowchart for operating the control system of a braking force control apparatus. It is a figure which shows the table | surface which shows the pressure change in the hydraulic system of the control system by the presence or absence of the action | operation of a braking force control apparatus. It is a figure which shows the pressure change of the brake fluid _concerning non-control apparatus 37 _FR by operation with a brake pedal and the solenoid valve which comprises the control system of a braking force control apparatus.

  Hereinafter, a braking force control apparatus according to an embodiment of the present invention will be described with reference to the drawings.

An example of a vehicle 10 to which the braking force control device is applied is shown in FIG. The vehicle 10 is provided with a power source 20 such as an engine or a motor. The vehicle 10 travels by transmitting the power of the power source 20 to the driving wheels as a driving force. The vehicle 10 is provided with a braking system that stops or decelerates the vehicle 10 during traveling. The braking system has a target wheel braking torque (target wheel) with individual sizes for each of the left front wheel (W _FL ), the right front wheel (W _FR ), the left rear wheel (W _RL ), and the right rear wheel (W _RR ). (Braking force) can be generated. Here, by utilizing the force of the brake fluid pressure of the frictional force is generated between the elements, each wheel _{W FL, W FR, W RL} , for those exerting target wheel braking torque (target wheel braking force) to W _RR explain. Thus, the braking force control device can perform ABS control, traction control, vehicle stability control (for example, VSC control), etc. by controlling the brake fluid pressure of the wheel to be controlled, and also can perform brake assist control. it can.

  As shown in FIGS. 1 and 2, the braking system of the present invention is configured so that a brake pedal 31 operated by a driver and an operation pressure (pedal pedaling force) accompanying a brake operation input to the brake pedal 31 are given a predetermined boost. A brake booster (brake booster) 32 that doubles the ratio and the pedal depression force doubled by the brake booster 32 is referred to as a brake hydraulic pressure (hereinafter referred to as a master cylinder pressure) corresponding to the operation amount of the brake pedal 31. ) And a reservoir tank 34 for storing brake fluid. The brake pedal 31, the brake booster 32, and the like function as a hydraulic pressure generator that generates a brake hydraulic pressure corresponding to the amount of operation of the brake pedal 31 by the driver. The master cylinder 33 is composed of two hydraulic chambers (not shown), and hydraulic pipes extend from the respective hydraulic chambers.

The braking system includes a hydraulic pressure adjusting device (hereinafter referred to as a brake actuator) 35 that can adjust the master cylinder pressure for each wheel W _FL , W _FR , W _RL , W _RR , and the brake actuator 35. The hydraulic pressure pipes 36 _FL , 36 _FR , 36 _{RL of} the wheels W _FL , W _FR , W _RL , W _RR to which the passed brake hydraulic pressure (master cylinder pressure or brake hydraulic pressure obtained by adjusting the master cylinder pressure) is transmitted 36 _RR and the brake fluid pressure of each of these hydraulic pipes 36 _FL , 36 _FR , 36 _RL , 36 _RR are respectively supplied to each wheel W _FL , W _FR , W _RL , W _RR. braking device for generating power) (those made up of those constituted by a disk rotor and the caliper or the like or a drum, a wheel cylinder or the like) 37 _L, and _{37 FR, 37 RL, 37 RR} , are provided.

The brake actuator 35 of the present embodiment includes a first hydraulic system that transmits brake hydraulic pressure to the right front wheel _WFR and the left rear wheel _WRL , and brake hydraulic pressure to the left front wheel _WFL and the right rear wheel _WRR . And a second hydraulic system that conveys the above. That is, the brake actuator 35 has a structure having a so-called X piping brake hydraulic pressure circuit. In the first hydraulic system, brake hydraulic pressure is supplied from one hydraulic chamber inside the master cylinder 33 via the first hydraulic pipe 38. On the other hand, in the second hydraulic system, the brake hydraulic pressure is supplied from the other hydraulic chamber inside the master cylinder 33 via the second hydraulic pipe 39.

The brake actuator 35 includes master cut valves 41 and 42 as respective brake fluid flow control devices in the first hydraulic system and the second hydraulic system. The master cut valve 41 is connected to the first hydraulic pipe 38, and the master cut valve 42 is connected to the second hydraulic pipe 39. Each of the master cut valves 41 and 42 is a so-called normally-open flow rate adjusting electromagnetic valve that is normally in an open state, and controls the valve opening degree according to energization according to a command from the electronic control unit 1. . Therefore, the master cut valves 41 and 42 are brakes introduced from the master cylinder 33 to the braking devices 37 _FL , 37 _FR , 37 _RL , and 37 _RR by controlling the valve opening according to the energization amount to the coil 102. The liquid flow is cut off. Further, the master cut valves 41 and 42 can be opened to the master cylinder 33 side by adjusting the brake fluid pressure discharged from the pressurizing pumps 69 and 70.

In the brake actuator 35, the first hydraulic pipe 38 is connected to the connecting passage 43 through the master cut valve 41, and the second hydraulic pipe 39 is connected to the connecting passage 44 through the master cut valve 42. The connecting passage 43 of the first hydraulic system is branched and connected to the two branch passages 45 and 46, and the connecting passage 44 of the second hydraulic system is connected to the two branch passages 47 and 48 by branching. To do. In the first hydraulic circuit, the branch passages 45 and 46 respectively connected to the right front wheel _{W FR} of the liquid pressure pipe _{36 FR} and the left rear wheels _{W RL} of the liquid pressure pipe _{36 RL.} On the other hand, in the second hydraulic circuit, connected to the branch passages 47 and 48 the liquid pressure piping _{36 FL} of the liquid pressure pipe _{36 RR} and a left rear wheel _{W FL,} respectively right rear wheel _{W RR.}

On each branch passage 45, 46, 47, 48, a hydraulic pressure adjusting unit capable of adjusting the brake hydraulic pressure for each of the braking devices 37 _FR , 37 _RL , 37 _RR , 37 _FL is provided on each wheel W _FR , W _RL , The holding valves 50, 51, 52, 53 arranged for each of W _RR , W _WL , the hydraulic pressure discharge passages 54, 55, 56, 57 and the pressure reducing valves 58, 59, 60, 61 are configured. Here, holding valves 50, 51, 52, 53 are arranged on the respective branch passages 45, 46, 47, 48, and further, hydraulic pressures downstream of the holding valves 50, 51, 52, 53 are arranged. discharge passage 54, 55, 56 and 57 are connected to branch from the respective liquid pressure line _{36 FL, 36 FR, 36 RL} , 36 RR. Pressure reducing valves 58, 59, 60, 61 are arranged on the hydraulic pressure discharge passages 54, 55, 56, 57, respectively. In addition, the downstream mentioned above is a downstream side in the flow direction of the brake fluid when the brake pedal is operated (that is, the direction toward the braking devices 37 _FR , 37 _RL , 37 _RR , 37 _FL ).

The holding valves 50, 51, 52, 53 are normally open solenoid valves as will be described later, and are normally opened in a non-excited state, and become energized in accordance with energization according to a command from the electronic control unit 1. It can be opened. Retention valves 50, 51, 52 and 53 is adapted to hold the brake fluid pressure flowing to the braking device _{37 FR, 37 RL, 37 RR} , 37 FL. On the other hand, the pressure reducing valves 58, 59, 60 and 61 are normally closed solenoid valves, which are normally closed in a non-excited state and are brought into an excited state in response to energization according to a command from the electronic control unit 1 and opened. It is what Pressure reducing valves 58, 59, 60, 61 is adapted to reduce the hydraulic pressure of the brake fluid flowing to the braking device _{37 FR, 37 RL, 37 RR} , 37 FL.

  In the brake actuator 35, the respective hydraulic pressure discharge passages 54, 55 in the first hydraulic pressure system merge to form one hydraulic pressure discharge coupling passage 62 and the respective hydraulic pressure discharge passages 56, 57 in the second hydraulic pressure system. One fluid pressure discharge coupling passage 63 is arranged so as to join, and each fluid pressure discharge collecting passage 62, 63 is connected to auxiliary reservoirs 64, 65, respectively.

  In the first hydraulic system, the pump passage 66 is arranged so as to branch from a branch point between the connecting passage 43 and the branch passages 45 and 46 and to be connected to the hydraulic discharge collecting passage 62. Similarly, the pump passage 67 is arranged so as to branch from a branch point between the connecting passage 44 and the branch passages 47 and 48 and to be connected to the hydraulic pressure discharge collecting passage 63.

The pump passages 66 and 67 are respectively provided with pressurizing pumps (pressurizing units) 69 and 70 driven by an electric motor (for example, one electric motor 68). The pressurizing pumps 69 and 70 discharge the brake fluid toward the branch points on the master cut valves 41 and 42 side, respectively, and apply pressure to the branch passages 45 and 46 and the branch passages 47 and 48, respectively. Supply the brake fluid pressure. That is, the first hydraulic pressure system pressurizing pump 69 supplies the brake hydraulic pressure supplied to the respective braking devices 37 _FL and 37 _RR in order to increase the braking force generated on the right front wheel W _FR and the left rear wheel W _RL. increase. The electric motor 68 is driven by power supply from a battery (not shown). Further, in each of the pump passages 66 and 67, damper chambers 71 and 72 for avoiding pulsation of the respective brake fluid discharged from the pressurizing pumps 69 and 70 are arranged.

  The brake actuator 35 is provided with suction passages 73 and 74 branched from the first and second hydraulic pipes 38 and 39 and connected to the auxiliary reservoirs 64 and 65, respectively. Further, reservoir cut check valves 75 and 76 are arranged on the auxiliary reservoirs 64 and 65 side of the respective suction passages 73 and 74.

For example, the braking force control device performs stabilization control of the vehicle behavior during turning. Stabilization control is vehicle stability control. The vehicle 10 may show a neutral steering tendency or an oversteering tendency or an understeering tendency during the turning motion accompanying the steering operation of the steering wheel 81 by the driver. The electronic control device 1 determines the behavior of the vehicle 10 based on vehicle travel information such as vehicle speed, vehicle longitudinal acceleration, lateral acceleration, yaw rate, and the like. The vehicle speed is determined from, for example, the wheel speeds of the wheels W _FL , W _FR , W _RL , W _RR (measured by the wheel speed sensors 91, 92, 93, 94), the rotational speed of the output shaft of the transmission (not shown), and the like. It may be estimated. The vehicle longitudinal acceleration is measured by the vehicle longitudinal acceleration sensor 95 and the vehicle lateral acceleration is measured by the vehicle lateral acceleration sensor 96. The yaw rate is measured by the yaw rate sensor 97.

  When the actual turning state of the vehicle body shows an excessive oversteer tendency, the electronic control unit 1 generates a wheel braking force on one or both of the front and rear turning outer wheels, thereby generating a yaw moment (actual A yaw moment (turning control amount) opposite to the turning behavior amount) can be applied to the vehicle body. Thus, when the vehicle body shows an oversteer tendency, the oversteer tendency can be suppressed by the wheel braking force generated on the turning outer wheel. The vehicle body 10 generates a turning control amount of an appropriate magnitude on the turning outer wheel, thereby suppressing the actual turning state that is excessively oversteered to the target turning state and performing the turning operation while maintaining the target turning state. Can do.

  Similarly, when the actual turning state of the vehicle body shows an excessive understeer tendency, the electronic control unit 1 generates a wheel braking force on one of the front and rear turning inner wheels, thereby generating a yaw moment (understeer tendency). A yaw moment (turning control amount) opposite to the actual turning behavior amount) can be applied to the vehicle body. Thus, when the vehicle body shows an understeer tendency, the understeer tendency can be suppressed by the wheel braking force generated on the turning outer wheel. The vehicle body 10 can generate a turning control amount of an appropriate magnitude in the turning outer wheel, thereby suppressing the actual turning state that tends to be an excessive understeer to the target turning state, and performing the turning operation while maintaining the target turning state. it can.

  The target turning state is a state of turning with a target turning behavior amount (a yaw moment having a target magnitude), for example, a state showing a neutral steer tendency or a weak understeer tendency. The electronic control unit 1 calculates a reverse target yaw moment (target turning control amount) to be generated for realizing the target turning state regardless of the tendency of the actual turning state of the vehicle body. The reverse target yaw moment is determined according to the difference between the actual turning state and the target turning state, in other words, the difference between the actual turning behavior amount and the target turning behavior amount.

  By the way, the braking force control device of the present invention does not include a master cylinder pressure sensor that measures the master cylinder pressure. Thus, the braking force control device of the present invention cannot grasp the change in the master cylinder pressure due to the driver's brake operation. Therefore, the braking force control apparatus according to the present invention uses the master cut valve 41 and the holding valve 50 to detect a change in the master cylinder pressure due to the driver's brake operation. Hereinafter, the master cut valve 42 has the same configuration as the master cut valve 41, and the same control is performed. Similarly, the holding valves 51, 52, and 53 have the same configuration as the holding valve 50, and the same control is performed, so that the description thereof is omitted.

  The master cut valve 41 according to the embodiment of the present invention is configured as shown in FIG. As shown in FIG. 3, the master cut valve 41 includes a magnetic body (plunger) 101, a coil 102, and a spring 103. The master cut valve 41 is a linear electromagnetic valve and linearly controls the brake fluid pressure by a current supplied to the coil 102.

  The magnetic body 101 is adapted to act in a direction in which a differential pressure acting force corresponding to a hydraulic pressure difference between the first hydraulic pipe 38 and the connecting passage 43 opens. The coil 102 generates an electromagnetic driving force when supplied with a current, and acts in a direction to close the magnetic body 101. The electromagnetic driving force can be controlled by controlling the current supplied to the coil 102. The spring 103 is configured to hold the magnetic body 101 in a movable state in a predetermined region.

  The master cut valve 41 moves the position of the magnetic body 101 by applying a voltage to the coil 102 when the brake fluid pumped up by the pressurizing pump 69 passes through the first hydraulic pipe 38 from the connection passage 43. Adjust. As a result, the master cut valve 41 generates a front-rear differential pressure (for example, a differential pressure between the first hydraulic pressure pipe 38 and the connection passage 43) according to the size of the flow path through which the brake fluid passes. That is, in the master cut valve 41, when the brake fluid passes through the magnetic body 101, a differential pressure is generated by the orifice effect.

  The holding valve 50 according to the embodiment of the present invention is configured as shown in FIG.

  As shown in FIG. 4, the holding valve 50 includes a magnetic body (plunger) 111, a coil 112, and a spring 113. Unlike the master cut valve 41, the holding valve 50 is an electromagnetic valve that is controlled by opening and closing. The magnetic body 111, the coil 112, and the spring 113 that constitute the holding valve 50 have the same configuration as the magnetic body 101, the coil 102, and the spring 103 that constitute the master cut valve 41.

Holding valve 50, the pressure difference between the fluid pressure of the brake fluid flowing in the first hydraulic system branched branch passage of the brake fluid flowing through the 45 hydraulic pressure and the wheels W _FR of the liquid pressure pipe 36 in the _FR from the connecting passage 43 of the The differential pressure due to acts in the direction to open the magnetic body 111. In addition, the holding valve 50 generates an electromagnetic driving force by applying a voltage to the coil 112 and acts in a direction to close the magnetic body 111. In other words, the holding valve 50 generates a differential pressure by balancing the pressure difference between the brake fluid before and after the holding valve 50 and the electromagnetic driving force.

  The pressure reducing valve 58 according to the embodiment of the present invention is configured as shown in FIG.

As shown in FIG. 5, the pressure reducing valve 58 includes a magnetic body (plunger) 121, a coil 122, and a spring 123. Unlike the master cut valve 41, the pressure reducing valve 58 is an electromagnetic valve that is controlled by opening and closing. The magnetic body 121, the coil 122, and the spring 123 that constitute the pressure reducing valve 58 have the same configuration as the magnetic body 111, the coil 112, and the spring 113 that constitute the holding valve 50. The pressure reducing valve 58 acts to open the magnetic body 121 by generating an electromagnetic driving force by applying a voltage to the coil 122. That is, the pressure reducing valve 58 moves the magnetic body 121 by applying an electromagnetic driving force, and reduces the hydraulic pressure of the brake fluid flowing to the braking device 37 _FR .

  The braking system has a pressure increasing mode for increasing the braking force of the wheel to be controlled, a holding mode for holding the braking force of the wheel to be controlled, and a pressure reducing mode for decreasing the braking force of the wheel to be controlled. When controlling the wheel to be controlled in the pressure increasing mode, the holding mode, or the pressure reducing mode, the electronic control unit 1 closes the master cut valves 41 and 42 of the hydraulic system including the wheel to be controlled.

When the wheel to be controlled is included in the first hydraulic system, the master cut valve 41 is closed, and the first hydraulic pipe 38 and the connection passage 43 upstream of the holding valves 50 and 51 are shut off. For example, when the right front wheel _WFR is a wheel to be controlled, the electronic control unit 1 controls the holding valve 50 to be in an open state and the pressure reducing valve 58 to be in a closed state when controlling the pressure increasing mode. Thus, the brake fluid pressure to the braking device 37 _FR of the right front wheel W _FR is increased. When the electronic control unit 1 controls to the holding mode, the control unit 37 _FR of the right front wheel W _FR is held by controlling the holding valve 50 and the pressure reducing valve 58 to be closed. . When the electronic control unit 1 controls the pressure reducing mode, the control unit 37 _FR for the right front wheel W _FR is controlled by controlling the holding valve 50 to be closed and the pressure reducing valve 58 to be opened. Reduce brake fluid pressure to

Similarly, when the wheel to be controlled is included in the second hydraulic system, the master cut valve 42 is closed and the second hydraulic pipe 39 and the connection passage 44 upstream of the holding valves 52 and 53 are shut off. To do. For example, when the left front wheel _WFL is a wheel to be controlled, the electronic control unit 1 performs control so that the holding valve 53 is opened and the pressure reducing valve 61 is closed when controlling to the pressure increasing mode. Thus, the brake fluid pressure to the braking device 37 _FL of the left front wheel W _FL is increased. When controlling the holding mode, the electronic control unit 1 controls the holding valve 53 and the pressure reducing valve 61 to be in a closed state, thereby holding the brake hydraulic pressure to the control unit 37 _FL of the left front wheel _WFL . . When the electronic control unit 1 controls the pressure reducing mode, the control unit 37 _FL for the left front wheel W _FL is controlled by controlling the holding valve 53 to be closed and the pressure reducing valve 58 to be opened. Reduce brake fluid pressure to

  The operation of the control system of the braking force control apparatus will be described using a control flowchart as shown in FIG.

  The braking force control device always determines whether or not to perform vehicle behavior stabilization control during driving. Thus, the control program for controlling the braking force in the present invention (that is, controlling the braking force of the non-control target wheel by detecting the operation of the brake pedal 31) is started every predetermined time. In step 610, the electronic control unit 1 detects whether vehicle behavior stabilization control is being performed. If the vehicle behavior stabilization control is not being performed, the electronic control unit 1 ends the control program. On the other hand, when the vehicle behavior stabilization control is being performed, the electronic control unit 1 proceeds to step 620.

In step 620, the electronic control unit 1 selects a non-control target wheel. The non-control target wheel is a wheel that does not control the braking force in order to accurately detect the vehicle speed of the vehicle 10 and control the braking force with respect to the control target wheel when performing the stabilization control of the vehicle behavior. It is. The non-control target wheel is changed according to the behavior of the vehicle depending on the shape of the traveling road and the steering angle of the driver. Hereinafter, it is assumed that the vehicle 10 has an oversteer tendency while turning left, and the braking force control device generates a clockwise moment in order to suppress the oversteer tendency. For simplification of description, the control target wheels are W _RL , W _RR , W _FL and the non-control target wheels are W _FR , but generally the control target wheels are W _FR , W _RR , W _FL. The non-control target wheel is _WRL .

The electronic control unit 1 proceeds from step 620 to step 630, and the differential pressure instruction value of the master cut valve 41 of the electronic control unit 1 is a non-controlled wheel W _FR, the differential pressure holding valve 50 of the non-controlled wheel W _FR The difference from the indicated value is set to a predetermined value 0.

In step 630, the differential pressure instruction value of the master cut valve 41 of the electronic control unit 1 is a non-controlled wheel W _FR, uncontrolled wheel W predetermined value and the differential pressure instruction value, a difference of the holding valve 50 _FR 0 As shown in FIG. 7, the setting is set to Tbl1 indicating a change in pressure in the hydraulic system of the control system depending on whether or not the braking force control device is activated. Tbl1 indicates the presence / absence of VSC control (vehicle behavior stabilization control) and the operation of the brake pedal 31 in the vertical direction, and the horizontal direction indicates the pressure in each component of the first hydraulic system (the brake fluid applied to the master cylinder 33). Pressure, the brake fluid pressure in the first hydraulic pipe, the pressure converted from the differential pressure command value of the master cut valve 41, the brake fluid pressure in the connecting passage 43 and the branch passage 45, and the differential pressure command value of the holding valve 50 And the brake fluid pressure in the hydraulic pipe 36 _FR ).

As an example, when the VSC control is not performed, the electronic control unit 1 controls the pressure applied to the master cut valve 41, the connection passage 43, and the holding valve 50 to be 10 MPa, respectively. The pressure of the master cylinder 33, the first hydraulic pipe 38 and the hydraulic pipe 36 _FR are set to 0 MPa. It is assumed that when the brake pedal 31 is operated, a pressure of 1 MPa is applied to the master cylinder 33. 1MPa is the pressure exerted on the master cylinder 33 is transmitted to the connecting passage 43 (branch path 45), a pressure of 1MPa is transmitted to the liquid pressure pipe _{36 FR.} That is, a braking force is applied to the wheel W _FR by applying a pressure of 1 MPa to the braking device 37 _FR . When VSC control is not performed, a pressure of 1 MPa is similarly applied to the other wheels W _FL , W _RL and W _RR . Thus, the hydraulic pressure of the brake fluid generated by the operation of the brake pedal 31 can be transmitted to the braking devices 37 _FL , 37 _FR , 37 _RL , 37 _RR and the braking force can be controlled.

On the other hand, during the VSC control, when the pressure pump 69 is operated, a pressure of 1 MPa is applied to the connection passage 43 (branch passage 45). Thus, the pressure applied to the connection passage 43 (branch passage 45) is 11 MPa. During the VSC control, pressure due to the operation of the pressurizing pump 69 is not applied to the non-control target wheel _WFR . That is, connecting passage 43 so as not to transmit the pressure of the liquid pressure pipe _{36 FR} of (branch passages 45) (control device _{37 FR),} a pressure holding valve 50 and 11 MPa. Accordingly, the pressure applied to the hydraulic pipe 36 _FR (control device 37 _FR ) is 0 MPa. In order to transmit the brake fluid pressure generated by the operation of the brake pedal 31, the pressure applied to the master cut valve 41 is set to 11 MPa, which is equivalent to the pressure applied to the holding valve 50.

It is assumed that 1 MPa is applied to the master cylinder 33 when the brake pedal 31 is operated during the VSC control. As in the case where the VSC control is not being performed, the pressure generated by the operation of the brake pedal 31 is transmitted through the first hydraulic pipe 38 and the connecting passage 43 (branch passage 45) to the hydraulic pipe 36 _FR (control device 37 _FR). ), The braking force can be controlled.

As described above, the electronic control unit 1 and the differential pressure instruction value of the master cut valve 41 of the non-controlled wheel W _FR, uncontrolled wheel W predetermined value and the differential pressure instruction value holding valve 50, the difference of the _FR By setting it to 0, the brake fluid pressure generated by the operation of the brake pedal 31 can be applied to the control device 37 _FR .

The electronic control unit 1 proceeds from step 630 to step 640, and outputs a pulse signal (a signal that repeats On-Off at a predetermined time interval) that instructs the pressure reducing valve 58 of the non-control target wheel _WFR to open. Send. When the electronic control unit 1 finishes the process of step 640, it ends the control program.

As shown in FIG. 8, the electronic control device 1 transmits a pulse signal that instructs the decompression valve 58 of the non-control target wheel _WFR to open the valve, as shown in FIG. The operation will be described.

In FIG. 8, the vertical axis indicates the differential pressure command value of the master cut valve 41, the differential pressure command value of the holding valve 50, the differential pressure command value of the pressure reducing valve 58, the operation of the brake pedal 31, and the pressure applied to the control device 37 _FR. The horizontal axis indicates the time transition t. First, the electronic control unit 1 sets the differential pressure instruction value of each electromagnetic valve to a predetermined value. At time t ₁ is made the control of vehicle stability, a differential pressure instruction value of the master cut valve 41 of the electronic control unit 1 is a non-controlled wheel W _FR, the differential pressure holding valve 50 of the non-controlled wheel W _FR The difference from the indicated value is increased to a predetermined value of 0.

When the vehicle behavior stabilization control is performed, the electronic control unit 1 transmits a pulse signal for changing the differential pressure instruction value to the pressure reducing valve 58. That is, the electronic control unit 1 opens and closes the pressure reducing valve 58 at predetermined time intervals. Here, when the driver is assumed that the operation of the brake pedal 31 to the time t _2, the pressure applied to the brake device 37 _FR increases. When the driver is operating the brake pedal 31, the pressure applied to the control device 37 _FR increases constantly. When the pressure reducing valve 58 is opened and closed at predetermined time intervals, the pressure applied to the control device 37 _FR once decreases, but returns to the predetermined pressure. When the driver finishes operating the brake pedal 31, the pressure applied to the braking device _37FR decreases to a predetermined value.

By performing the control as described above, the flow rate to be pumped to the control device 37 _FR of uncontrolled wheel W _FR, depending if boosts the hydraulic pressure of the brake fluid by the operation of the brake pedal 31 and the pressurizing pump 69 it but to depressurizing the fluid pressure of the brake fluid, such as when the liquid pressure is boosts, uncontrolled wheel W _FR brake fluid according to the control apparatus 37 _FR for by changing to a predetermined value which is a target control amount it can.

  In addition, this invention is not limited to the said embodiment, A various modified example is employable within the scope of the present invention.

For example, in the above embodiment, when the hydraulic pressure in the hydraulic system of the control system fluctuates, the pressure of the master cut valve 41 is changed. However, by changing the pressure of the holding valve 50, the non-control target wheel a differential pressure instruction value of the master cut valve 41 of the W _FR, the differential pressure instruction value holding valve 50 of the non-controlled wheel W _FR, the difference may be controlled so as to increase or smaller than a predetermined value of.

Further, according to the above embodiment, the flow rate passing through the master cut valve 41 is calculated from the flow rate of the pressurization pump 69, but the control target wheel W of the same hydraulic system (first hydraulic system). You may make it calculate from the inflow amount of the brake fluid to _RL . Inflow of the brake fluid to the controlled object wheels W _RL of the same hydraulic circuit (first hydraulic circuit) is calculated from the differential pressure instruction amount of the holding valves 51.

  Furthermore, according to the above-described embodiment, the pressure reducing valve 58 is opened at predetermined time intervals during the control of the vehicle behavior stabilization. However, the control of the vehicle behavior stabilization may not be performed.

_{DESCRIPTION OF SYMBOLS} 1 ... Electronic control apparatus, 10 ... Vehicle, _WFL ( _WFR , _WRL , _WRR ) ... Wheel, 31 ... Brake pedal, 33 ... Master cylinder, _36FL ( _36FR , _36RL , _36RR ) ... _Hydraulic pressure Piping, 37 _FL (37 _FR , 37 _RL , 37 _RR ) ... Brake device, 41 (42) ... Master cut valve, 43 (44) ... Connection passage, 45 (46) ... Branch passage, 50 (51, 52, 53) ) ... Holding valve, 58 (59, 60, 61) ... Pressure reducing valve

Claims (4)

A master cylinder that generates pressure in the fluid by operating the brake pedal;
A braking device for generating a braking force by the pressure of the fluid;
A pipe connecting the master cylinder and the braking device;
A first solenoid valve operated to block the flow of fluid in the pipe;
A second solenoid valve operated to maintain the pressure of the fluid flowing through the braking device;
A third solenoid valve operated to reduce the pressure of the fluid flowing to the braking device,
The difference between the first differential pressure command amount given to control the first solenoid valve and the second differential pressure command amount given to control the second solenoid valve is set to a predetermined value. A braking force control device that controls and controls the braking force by opening the third electromagnetic valve for a predetermined time. The braking force control apparatus according to claim 1, wherein the braking force is controlled by opening the third electromagnetic valve for a predetermined time during the braking force control. The braking force control device according to claim 1 or 2, wherein the braking force is controlled by opening the third electromagnetic valve based on a pulse signal instructing to open the third electromagnetic valve. The braking force control device according to any one of claims 1 to 3, wherein the braking force control device is a vehicle behavior stabilization control device that performs vehicle behavior stabilization control.

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