JP4124048B2 - Braking force control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle braking force control device, and more particularly to a so-called electronically controlled braking force control device.

  In vehicles such as automobiles, there is a communication control valve that controls the communication between the master cylinder and the wheel cylinder of each wheel, and the pressure of the high pressure source based on at least the master cylinder pressure with the communication control valve closed. As one of the braking force control devices for controlling the wheel cylinder pressure of each wheel using, for example, the master cylinder pressure and the depression of the brake pedal as described in the following Patent Document 1 relating to the application of the present applicant. The stroke is detected, the target wheel cylinder pressure of each wheel is calculated based on the master cylinder pressure and the brake pedal depression stroke, and the control valve for each wheel is controlled so that the wheel cylinder pressure of each wheel becomes the target wheel cylinder pressure. Conventionally, a braking force control device that performs this is known.

Further, in a vehicle equipped with a braking force control device having a communication control valve as described above, the braking force of each wheel can be controlled independently of the driver's braking operation. If this happens, braking force is automatically applied to the specified wheels to stabilize the vehicle behavior, or when there is a possibility that the vehicle may collide with a front obstacle, or the inter-vehicle distance from the preceding vehicle is small. An automatic braking device that automatically applies a braking force to a wheel when the vehicle becomes automatic and decelerates the vehicle automatically is also known.
JP 2002-316630 A

  In general, when the braking force of a wheel is controlled by either a braking force control device or an automatic braking device, the wheel cylinder of each wheel is used by using the pressure of a high pressure source with the communication control valve closed. If the pressure is controlled but the pressure increase / decrease control valve becomes abnormal and the wheel cylinder pressure cannot be controlled, the communication control valve is opened for the wheel, and the wheel cylinder of the wheel is connected to the master cylinder. To be.

  Therefore, when the braking force of the predetermined wheel is controlled by the automatic braking device, if an abnormality occurs in the pressure increase / decrease control valve of the predetermined wheel and the corresponding communication control valve is opened, the communication control valve The high-pressure working fluid on the wheel cylinder side flows back to the master cylinder through the communication control valve, and the master cylinder pressure rises rapidly and instantaneously. Accordingly, an unnecessary high target wheel cylinder pressure is calculated based on the increased master cylinder pressure, and the wheel cylinder pressure of each wheel is controlled to become the target wheel cylinder pressure. There is a problem of being imparted, and this problem is particularly remarkable when an orifice is incorporated in the master cylinder in order to improve the brake operation feeling.

  The present invention relates to a conventional braking force control device configured to control wheel braking force by controlling wheel cylinder pressure in a state where communication between a master cylinder and a wheel cylinder is blocked by a communication control valve, and automatic braking. The main problem of the present invention is that when the communication control valve is opened during operation of the automatic braking device, high-pressure working liquid is transferred to the master cylinder. By preventing the braking force of the wheel from being controlled based on the master cylinder pressure that has increased due to the backflow, unnecessary braking force is prevented from being applied to the wheel.

According to the present invention, the main problem described above includes a communication control valve that controls communication between the master cylinder and the wheel cylinder of each wheel, and at least the master cylinder pressure is maintained in a state in which the communication control valve is closed. In the vehicle braking force control apparatus that controls the wheel cylinder pressure of each wheel using the pressure of the high pressure source based on the pressure of the high pressure source regardless of the braking operation of the brake operator by the driver. And an automatic braking device that controls the wheel cylinder pressure of a predetermined wheel, and when the communication control valve is switched from the closed state to the open state during operation of the automatic braking device, the braking operation element If the braking operation has not been performed for is detected by the braking operation detecting means, it is at above its switching point within a predetermined time based on the master cylinder pressure each A vehicle braking force control device (constituting claim 1) for suppressing control of wheel cylinder pressure of a wheel, or a communication control valve for controlling communication between a master cylinder and a wheel cylinder of each wheel In the vehicle braking force control device for controlling the wheel cylinder pressure of each wheel by using the pressure of the high pressure source based on at least the master cylinder pressure with the communication control valve closed, the vehicle is operated. An automatic braking device that controls the wheel cylinder pressure of a predetermined wheel using the pressure of a high pressure source regardless of the braking operation of the braking operator by the operator, and the communication control valve is operated during the operation of the automatic braking device. When the valve is switched from the closed state to the open state, the control of the wheel cylinder pressure of each wheel based on the master cylinder pressure is suppressed until a braking operation is performed by the driver. It is achieved by the braking force control apparatus for a vehicle characterized by (the second aspect) to.

Further, according to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 2 , there is provided a braking operation detecting means for detecting a braking operation of the driver with respect to the braking operator, The control of the wheel cylinder pressure is configured to be performed when it is detected by the braking operation detection means that no braking operation is being performed on the braking operation element (configuration of claim 3).

  According to the present invention, in order to effectively achieve the main problems described above, the braking force control device according to any one of claims 1 to 3 is configured so that the target wheel cylinder of each wheel is based on at least the master cylinder pressure. While calculating the pressure, the wheel cylinder pressure of each wheel is controlled to become the corresponding target wheel cylinder pressure, and the control of the wheel cylinder pressure is controlled when there is a control amount of the wheel cylinder pressure based on the target wheel cylinder pressure. It is comprised so that it may be performed (structure of Claim 4).

  According to the present invention, in order to effectively achieve the main problems described above, the braking force control device according to any one of claims 1 to 4, wherein the braking force control device operates the master cylinder pressure and the operation of the braking operator by the driver. Calculate the target wheel cylinder pressure of each wheel based on the amount of displacement, and control the wheel cylinder pressure of each wheel to be the corresponding target wheel cylinder pressure to reduce the contribution of the master cylinder pressure to the target wheel cylinder pressure Thus, the control of the wheel cylinder pressure of each wheel based on the master cylinder pressure is suppressed (configuration of claim 5).

  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 5, the braking force control device is based on only the operation displacement amount of the braking operator by the driver. By calculating the target wheel cylinder pressure of the wheel, the contribution degree of the master cylinder pressure to the target wheel cylinder pressure is reduced to 0 (configuration of claim 6).

According to the above configuration, when the communication control valve is switched from the closed state to the open state during the operation of the automatic braking device, each wheel based on the master cylinder pressure is within a predetermined time from the switching point. Since the control of the wheel cylinder pressure is suppressed, the communication control valve is switched to the open state, and even if the master cylinder pressure rises due to the backflow of high pressure hydraulic fluid to the master cylinder, the increased master cylinder pressure By controlling the braking force of the wheel based on the above, it is possible to effectively prevent an unnecessary braking force from being applied to the wheel.

Further , according to the above configuration, when the communication control valve is switched from the closed state to the open state during the operation of the automatic braking device, the wheel of each wheel based on the master cylinder pressure until the braking operation is performed by the driver. Since the control of the cylinder pressure is suppressed, it is possible to effectively prevent unnecessary braking force from being applied to the wheels, and to ensure the braking force control that surely reflects the driver's braking intention. be able to.

As described above, are performed when the possible suppression of the control of the wheel cylinder pressure braking operation to brake operation element by the brake operation detecting means is not performed is detected lever, which braking operation is performed by the driver Even if the control of the wheel cylinder pressure is not suppressed and the master cylinder pressure rises and the braking force of the wheel rises, the driver ensures the desired vehicle deceleration by adjusting the braking operation amount with respect to the brake operator In addition, it is possible to reliably prevent unnecessary braking force from being applied to the wheel when the driver does not perform the braking operation.

  According to the configuration of claim 4, the target wheel cylinder pressure of each wheel is calculated based on at least the master cylinder pressure, and the wheel cylinder pressure of each wheel is controlled to become the corresponding target wheel cylinder pressure. Since the suppression of the cylinder pressure control is performed when there is a control amount of the wheel cylinder pressure based on the target wheel cylinder pressure, it is possible to prevent the control of the wheel cylinder pressure from being performed unnecessarily.

  According to the fifth aspect of the present invention, the target wheel cylinder pressure of each wheel is calculated based on the master cylinder pressure and the operation displacement amount of the brake operator by the driver, and the wheel cylinder pressure of each wheel corresponds to the target. Since the control of the wheel cylinder pressure is controlled to reduce the contribution of the master cylinder pressure to the target wheel cylinder pressure, the control of the wheel cylinder pressure of each wheel based on the master cylinder pressure is suppressed. Compared to the case where the contribution degree of the master cylinder pressure is not lowered, the possibility that an unnecessary braking force is applied to the wheels can be reliably reduced.

  According to the configuration of the sixth aspect, the target wheel cylinder pressure of each wheel is calculated based only on the amount of braking operation of the driver with respect to the braking operator, so that the contribution degree of the master cylinder pressure to the target wheel cylinder pressure is calculated. Therefore, even if the master cylinder pressure rises due to the high-pressure working liquid flowing back to the master cylinder, it is possible to reliably prevent unnecessary braking force from being applied to the wheels.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of claim 1, the braking force control device controls the pressure increasing / reducing control valve based on at least the master cylinder pressure with the communication control valve closed. The pressure of the high pressure source is used to control the wheel cylinder pressure of each wheel, and the communication control valve is configured to be switched from the open state to the closed state when an abnormality occurs in the corresponding pressure increasing / decreasing control valve. (Preferred embodiment 1).

  According to another preferred aspect of the present invention, in the configuration of claim 1, the braking operation by the driver is determined by the operation displacement amount of the braking operator by the driver (preferred embodiment). 2).

  According to another preferred aspect of the present invention, in the configuration of claim 3, the braking operation detection means is configured to detect an operation displacement amount of the braking operator by the driver (Preferred embodiment 3). .

  According to another preferred aspect of the present invention, in the configuration of claim 4, the braking force control device is configured such that the target wheel cylinder of each wheel is based on the master cylinder pressure and the operation displacement amount of the braking operator by the driver. It is comprised so that a pressure may be calculated (Preferred aspect 4).

  According to another preferred aspect of the present invention, in the configuration of claim 5, the braking force control device is based on a target braking control amount based on the master cylinder pressure and an operation displacement amount of the braking operator by the driver. The target wheel cylinder pressure of each wheel is calculated based on the sum of weights with the target brake control amount, and the contribution of the master cylinder pressure to the target wheel cylinder pressure is reduced by reducing the weight of the target brake control amount based on the master cylinder pressure. (Preferred aspect 5).

  According to another preferred embodiment of the present invention, the communication control valve is configured so as to be a normally open electromagnetic on-off valve in the configuration of the first to sixth aspects (preferred embodiment 6).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a hydraulic circuit of a first embodiment of a vehicle braking force control device according to the present invention applied to a vehicle equipped with a behavior control device as an automatic braking device, and FIG. 2 shows a braking force of the first embodiment. It is a block diagram which shows the control system of a control apparatus and a behavior control apparatus. In FIG. 1, the solenoid of each valve is not shown for the sake of simplicity.

  In FIG. 1, reference numeral 10 denotes an electrically controlled hydraulic brake device. The brake device 10 includes a master cylinder 14 that pumps brake oil in response to a driver's depressing operation of the brake pedal 12. Have. A dry stroke simulator 16 is provided between the brake pedal 12 and the master cylinder 14.

  The master cylinder 14 has a first master cylinder chamber 14A and a second master cylinder chamber 14B, and these master cylinder chambers have a brake hydraulic pressure supply conduit 18 for the left front wheel and a brake hydraulic pressure control conduit for the right front wheel, respectively. One end of 20 is connected. Wheel cylinders 22FL and 22FR for controlling the braking force of the left front wheel and the right front wheel are connected to the other ends of the brake hydraulic pressure control conduits 18 and 20, respectively.

  In the middle of the brake hydraulic pressure supply pipes 18 and 20, normally open type electromagnetic on / off valves (master cut valves) 24L and 24R are provided, respectively. The electromagnetic on / off valves 24L and 24R are respectively connected to the first master cylinder chamber 14A and the second master cylinder chamber 14A. It functions as a shut-off valve that controls communication between the master cylinder chamber 14B and the corresponding wheel cylinders 22FL and 22FR. A wet stroke simulator 28 is connected to the brake hydraulic pressure supply conduit 18 between the master cylinder 14 and the electromagnetic open / close valve 24FL via a normally closed electromagnetic open / close valve (normally closed valve) 26.

  A reservoir 30 is connected to the master cylinder 14, and one end of a hydraulic pressure supply conduit 32 is connected to the reservoir 30. An oil pump 36 driven by an electric motor 34 is provided in the middle of the hydraulic supply conduit 32, and an accumulator 38 that accumulates high-pressure hydraulic pressure is connected to the hydraulic supply conduit 32 on the discharge side of the oil pump 36. One end of a hydraulic discharge conduit 40 is connected to the hydraulic supply conduit 32 between the reservoir 30 and the oil pump 36. The reservoir 30, the oil pump 36, the accumulator 38, and the like function as a high pressure source for increasing the pressure in the wheel cylinders 22FL, 22FR, 22RL, and 22RR as will be described later.

  Although not shown in FIG. 1, a conduit is provided for connecting the suction-side hydraulic supply conduit 32 and the discharge-side hydraulic supply conduit 32 of the oil pump 36, and an accumulator 38 is provided in the middle of the conduit. A relief valve is provided that opens when the pressure exceeds a reference value and returns oil from the discharge-side hydraulic supply conduit 32 to the suction-side hydraulic supply conduit 32.

  The hydraulic pressure supply conduit 32 on the discharge side of the oil pump 36 is connected to the brake hydraulic pressure supply conduit 18 between the electromagnetic on-off valve 24L and the wheel cylinder 22FL by a hydraulic control conduit 42, and the electromagnetic on-off valve 24R and the wheel by a hydraulic control conduit 44. It is connected to a brake hydraulic pressure supply conduit 20 between the cylinder 22FR, a hydraulic control conduit 46 to a left rear wheel wheel cylinder 22RL, and a hydraulic control conduit 48 to a right rear wheel wheel cylinder 22RR. .

  Normally closed electromagnetic linear valves 50FL, 50FR, 50RL, and 50RR are provided in the middle of the hydraulic control conduits 42, 44, 46, and 48, respectively. The hydraulic control conduits 42, 44, 46, 48 on the side of the wheel cylinders 22FL, 22FR, 22RL, 22RR with respect to the linear valves 50FL, 50FR, 50RL, 50RR are connected to the hydraulic discharge conduit 40 by the hydraulic control conduits 52, 54, 56, 58, respectively. And normally closed electromagnetic linear valves 60FL and 60FR are provided in the middle of the hydraulic control conduits 52 and 54, respectively, and normally closed electromagnetic solenoids are provided in the middle of the hydraulic control conduits 56 and 58, respectively. There are provided normally-open electromagnetic linear valves 60RL and 60RR that are cheaper than the conventional linear valves.

  The linear valves 50FL, 50FR, 50RL, and 50RR function as pressure increase valves (holding valves) for the wheel cylinders 22FL, 22FR, 22RL, and 22RR, respectively. The linear valves 60FL, 60FR, 60RL, and 60RR are wheel cylinders 22FL, 22FR, 22RL, and The linear valves function as pressure reducing valves for 22RR, so that these linear valves form a pressure increasing / decreasing control valve for controlling supply / discharge of high pressure oil to / from each wheel cylinder from the accumulator 38 in cooperation with each other.

  Note that the electromagnetic on / off valves 24L and 24R are kept open during non-control when no drive current is supplied to the electromagnetic on / off valves, linear valves and motor 34, and the electromagnetic on / off valves 26, linear valves 50FL to 50RR, linear valves 60FL and 60FR is maintained in a closed state, and linear valves 60RL and 60RR are maintained in an open state (non-control mode). In addition, when any one of the linear valves 50FL to 50RR and the linear valves 60FL to 60RR is lost and the pressure in the corresponding wheel cylinder cannot be normally controlled, each electromagnetic on-off valve is set to the non-control mode. As a result, the pressure in the wheel cylinders of the left and right front wheels is directly controlled by the master cylinder 14.

  As shown in FIG. 1, a brake hydraulic pressure control conduit 18 between the first master cylinder chamber 14A and the electromagnetic on-off valve 24L detects a pressure in the control conduit as a first master cylinder pressure Pm1. One pressure sensor 66 is provided. Similarly, the brake pressure control conduit 20 between the second master cylinder chamber 14B and the electromagnetic on-off valve 24R is provided with a second pressure sensor 68 for detecting the pressure in the control conduit as the second master cylinder pressure Pm2. It has been. The brake pedal 12 is provided with a stroke sensor 70 for detecting a brake pedal depression stroke St by a driver, and a pressure for detecting the pressure in the conduit as an accumulator pressure Pa is provided in a hydraulic supply conduit 32 on the discharge side of the oil pump 34. A sensor 72 is provided.

  Pressure sensors for detecting the pressure in the corresponding conduits as the pressures Pfl and Pfr in the wheel cylinders 22FL and 22FR are provided in the brake hydraulic pressure supply conduits 18 and 20 between the electromagnetic on-off valves 24L and 24R and the wheel cylinders 22FL and 22FR, respectively. 74FL and 74FR are provided. Further, in the hydraulic control conduits 46 and 48 between the electromagnetic on-off valves 50RL and 50RR and the wheel cylinders 22RL and 22RR, respectively, pressure sensors for detecting the pressure in the corresponding conduits as the pressures Prl and Prr in the wheel cylinders 22RL and 22RR. 74RL and 74RR are provided.

  The electromagnetic on / off valves 24L and 24R, the electromagnetic on / off valve 26, the motor 34, the linear valves 50FL to 50RR, and the linear valves 60FL to 60RR are controlled by an electronic control unit 78 shown in FIG. 2 as will be described in detail later. The electronic control unit 78 includes a microcomputer 80 and a drive circuit 82. Although not shown in detail in FIG. 1, the microcomputer 80 has, for example, a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other via a bidirectional common bus. It may be.

  In the microcomputer 80, a signal indicating the first master cylinder pressure Pm1 and the second master cylinder pressure Pm2 from the pressure sensors 66 and 68, a signal indicating the depression stroke St of the brake pedal 12 from the stroke sensor 70, and a pressure sensor 72, respectively. A signal indicating the accumulator pressure Pa and a signal indicating the pressure Pi (i = fl, fr, rl, rr) in the wheel cylinders 22FL-22RR are input from the pressure sensors 74FL-74RR, respectively.

  The microcomputer 80 stores a braking force control routine according to the flowchart shown in FIG. 3 as will be described later. When the brake pedal 12 is depressed, the electromagnetic opening / closing valve 26 is opened and the electromagnetic opening / closing valves 24L and 24R are opened. The target wheel cylinder pressure Pti (i = fl, fr) of each wheel is closed based on the master cylinder pressures Pm1, Pm2 detected by the pressure sensors 66, 68 and the depression stroke St detected by the stroke sensor 70 in that state. , Rl, rr) are calculated to be higher than the master cylinder pressures Pm1, Pm2, and the linear valves 50FL-50RR and 60FL-60RR are controlled so that the braking pressure Pi of each wheel becomes the target wheel cylinder pressure Pti.

  As will be understood from the above description, the microcomputer 80 calculates the target wheel cylinder pressure of each wheel based on the braking operation amount of the driver, and the electromagnetic on / off valves 24L and 24R, the electromagnetic on / off valve 26, the electric motor 34, and the linear valves 50FL to 50RR. In addition, the solenoid valves 24L and 24R are closed using the pressure of the high pressure source in cooperation with the sensors such as the linear valves 60FL to 60RR, the electronic control device 78, and the pressure sensor 66. Control means for controlling the wheel cylinder pressure to become the corresponding target wheel cylinder pressure is configured.

  In the illustrated embodiment, the braking force of the wheels is also controlled by the electronic control device 84 of the behavior control device. The electronic control unit 84 includes a microcomputer 86 having a configuration similar to that of the microcomputer 80, and exchanges necessary information with the microcomputer 80. The microcomputer 86 includes a signal indicating the steering angle θ detected by the steering angle sensor 88, a signal indicating the yaw rate γ detected by the yaw rate sensor 90, a signal indicating the longitudinal acceleration Gx detected by the longitudinal acceleration sensor 92, and a lateral acceleration. A signal indicating the lateral acceleration Gy detected by the sensor 94 and a signal indicating the vehicle speed V detected by the vehicle speed sensor 96 are input.

  Although not shown in the figure as a flowchart, the microcomputer 86 has a spin state amount SS indicating the degree of vehicle spin based on a vehicle state amount that changes as the vehicle travels, and a drift-out state indicating the degree of vehicle drift-out. Calculate the amount DS, calculate the target braking force or target slip ratio of each wheel for behavior control that stabilizes the vehicle behavior based on the spin state amount SS and the drift-out state amount DS, and close the solenoid valves 24L and 24R. Regardless of the driver's braking operation, the braking pressure of each wheel is controlled according to the target braking force or the target slip ratio by using the pressure of the high pressure source in the valved state. To stabilize the behavior of the vehicle.

  For example, when the vehicle is in a spin state, the microcomputer 86 applies a braking force to the front wheels on the outside of the turn to apply a yaw moment in the spin suppression direction to the vehicle, and suppresses spin when the vehicle is in a drift-out state. The braking force is applied to the rear wheels to decelerate the vehicle, and the vehicle is given a yaw moment in the turning assist direction to suppress drift-out.

  In the illustrated embodiment, although not shown in the drawing as a flowchart, the microcomputer 80 performs a self-diagnosis on the brake device 10 and takes necessary measures according to the diagnosis result. In particular, the microcomputer 80 responds when an abnormality occurs in either the linear valve 50FL to 50RR as the pressure increasing valve of each wheel or the linear valve 60FL to 60RR as the pressure reducing valve, and the wheel cylinder pressure cannot be properly controlled. The electromagnetic on-off valve 24L or 24R is opened to connect the wheel cylinder and the master cylinder chamber 14A or 14B, and an alternative control known in the art is performed.

  In particular, in the illustrated embodiment, the microcomputer 80 has an electromagnetic on-off valve in which an abnormality occurs in one of the left and right front linear valves in a situation where the behavior control is performed by the electronic control device 84 of the behavior control device. When the valve 24L or 24R is opened, in principle, the target wheel cylinder pressure of each wheel is based only on the stepping stroke St detected by the stroke sensor 70 for a predetermined time from the time when the electromagnetic on-off valve 24L or 24R is opened. Pti is calculated, and the target wheel cylinder pressure is calculated on the basis of the master cylinder pressures Pm1 and Pm2 that are increased by the backflow of high-pressure oil on the wheel cylinder side to the master cylinder 14 from the electromagnetic on-off valve 24L or 24R. This prevents unnecessary braking force from being applied to the wheels.

  Next, the braking force control in the first embodiment will be described with reference to the flowchart shown in FIG. Note that the control according to the flowchart shown in FIG. 2 is started when the microcomputer 80 is activated, and is repeatedly executed at predetermined time intervals. The flag Fa relates to whether or not an abnormality has occurred in any of the linear valves on the left and right front wheels, and 1 indicates that an abnormality has occurred in any of the linear valves on the left and right front wheels.

  First, in step 10, it is determined whether or not the flag Fa is 1, that is, whether or not an abnormality has occurred in any of the linear valves on the left and right front wheels. Proceed to 30, and when an affirmative determination is made, proceed to step 20.

  In step 20, for example, whether or not the brake pedal 12 is depressed by the driver is determined by determining whether or not the depression stroke St detected by the stroke sensor 70 is greater than or equal to a reference value Sto (positive constant). If a determination is made and an affirmative determination is made, the process proceeds to step 110. If a negative determination is made, the process proceeds to step 60.

  In step 30, it is determined whether or not there is a braking request by the driver. If a negative determination is made, the process proceeds to step 40, and if an affirmative determination is made, the process proceeds to step 130. Whether or not there is a braking request by the driver is determined by, for example, whether the average value Pma of the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 is equal to or greater than the start reference value Pms (positive constant) or It may be performed by determining whether or not the stepping stroke St detected by the stroke sensor 70 is greater than or equal to the start reference value Sts (positive constant).

  In step 40, it is determined whether or not the control for applying the braking force to the left front wheel is performed by the behavior control device. If a negative determination is made, the process proceeds to step 60, where an affirmative determination is made. Sometimes go to step 50.

  In step 50, for example, it is determined whether an abnormality has occurred in the linear valve 50FL or 60FL for the left front wheel and the left front wheel has changed from the braking force control permitted state to the braking force control prohibited state, and an affirmative determination is made. If yes, the process proceeds to step 100. If a negative determination is made, the process proceeds to step 60.

  In step 60, for example, it is determined whether or not the left front wheel is within a predetermined time Tofl (positive constant) from the time point when the braking force control permission state changes to the braking force control prohibition state. If so, the process proceeds to step 100. If a negative determination is made, the process proceeds to step 70.

  Similarly, in step 70, it is determined whether or not the control for applying the braking force to the right front wheel is performed by the behavior control device. If a negative determination is made, the process proceeds to step 90, where an affirmative determination is made. If so, go to Step 80.

  In step 80, for example, it is determined whether an abnormality has occurred in the linear valve 50FR or 60FR for the right front wheel, and the right front wheel has changed from the braking force control permitted state to the braking force control prohibited state. If YES, the process proceeds to step 100. If a negative determination is made, the process proceeds to step 90.

  In step 90, for example, it is determined whether or not the right front wheel is within a predetermined time Tofr (positive constant) from the time when the braking force control permission state changes to the braking force control prohibition state. If so, the flag Fa is set to 1 in step 100, and if negative determination is made, the flag Fa is reset to 0 in step 110. Note that the predetermined times Tofl and Tofr in steps 60 and 90 are the instantaneous values of the master cylinder pressures Pm1 and Pm2 caused by the opening of the electromagnetic on-off valve 24L or 24R and the high pressure oil flowing back to the master cylinder 14. It is set to the time when the rise stops.

  In step 130, it is determined whether or not the flag Fa is 0, that is, whether or not the linear valves of the left and right front wheels are normal. If a negative determination is made, the process proceeds to step 180, where an affirmative determination is made. If YES, step 140 follows.

  In step 140, a signal indicating the master cylinder pressure Pm1 detected by the pressure sensor 66 is read, and a map corresponding to the graph shown in FIG. 6 based on the average value Pma of the master cylinder pressures Pm1 and Pm2. Thus, the target deceleration Gpt based on the master cylinder pressure is calculated.

  In step 150, based on the depression stroke St detected by the stroke sensor 70, a target deceleration Gst based on the depression stroke is calculated from a map corresponding to the graph shown in FIG.

In step 160, the weight α (0 ≦ α ≦ 1) for the target deceleration Gpt is calculated from the map corresponding to the graph shown in FIG. 8 based on the previous final target deceleration Gtf, and the following equation is used: According to 1, the final target deceleration Gt is calculated as a weighted sum of the target deceleration Gpt and the target deceleration Gst. In the illustrated embodiment, the weight α is calculated based on the previous final target deceleration Gtf, but may be modified to be calculated based on the target deceleration Gpt or Gst.
Gt = α · Gpt + (1−α) Gst (1)

In Step 170, Ki (i = fl, fr, rl, rr) is defined as a coefficient of the target wheel cylinder pressure of each wheel with respect to the final target deceleration Gt (a positive coefficient considering the braking effectiveness coefficient of each wheel). The target wheel cylinder pressure Pti (i = fl, fr, rl, rr) of each wheel is calculated according to the following formula 2.
Pti = Ki ・ Gt (2)

  In step 180, the target deceleration Gst based on the depression stroke is calculated from the map corresponding to the graph shown in FIG. 7 based on the depression stroke St detected by the stroke sensor 70 as in step 150.

  In step 190, the final target deceleration Gt is set to the target deceleration Gst based on the depression stroke, and in step 190, the target wheel cylinder is set based on the target deceleration Gst for the wheels other than the wheel in which the linear valve is abnormal. The pressure Pti is calculated.

  In step 210, control is performed by hydraulic feedback so that the wheel cylinder pressure Pi of the wheel becomes the target wheel cylinder pressure Pti. When the target wheel cylinder pressure Pti is calculated in step 190, the electromagnetic on / off valve 24L or 24R corresponding to the wheel is opened, so that the braking force is not controlled for the wheel.

  Next, the operation of the illustrated embodiment 1 will be described by classifying the situation of the braking force control device.

(1) When the braking operation is performed in a state where the linear valves and the like are normal If a braking operation is performed by the driver in a state where all the linear valves and the like are normal, a negative determination is made in step 10. At steps 20 and 130, an affirmative determination is made, and at steps 140 to 170, the target wheel cylinder pressure Pti of each wheel is calculated based on the average value Pma of the master cylinder pressures Pm1 and Pm2 and the depression stroke St. In step 210, the brake cylinders are controlled in a brake-by-wire manner with the electromagnetic on-off valves 24L and 24R closed so that the wheel cylinder pressure Pi of each wheel becomes a target braking pressure Pti higher than the master cylinder pressures Pm1 and Pm2. The

(2) When behavior control is performed in a state where the linear valves and the like are normal When the behavior control is performed by the behavior control device in a state where all the linear valves are normal, the electromagnetic on-off valves 24L and 24R With the valve closed, the wheel cylinder pressure Pi of a predetermined wheel is controlled in accordance with the behavior state of the vehicle irrespective of the driver's braking operation, thereby stabilizing the behavior of the vehicle.

(3) When an abnormality occurs in the front wheel linear valve during behavior control during non-braking operation One of the left and right front wheel linear valves during behavior control in a situation where the driver does not perform braking operation If an abnormality occurs, the electromagnetic on-off valve 24L or 24R of the wheel is opened, and the behavior control is interrupted. In this case, a negative determination is first made in steps 10 and 30, an affirmative determination is made in steps 40 and 50, whereby the flag Fa is set to 1 in step 100, and step 130 is executed. In this case, a negative determination is made.

  From the next cycle onwards, until a negative determination is made at step 60, an affirmative determination is made at step 10, and a negative determination is made at step 20, whereby the electromagnetic on-off valve 24L or 24R is opened. The flag Fa is maintained at 1 until a predetermined time Tofl elapses from the point in time, and a negative determination is made in step 130, so that each wheel is determined based on only the stepping stroke St in steps 180 to 200. The target wheel cylinder pressure Pti is calculated.

  In this case, since the braking operation is not performed and the stepping stroke St is 0, the target deceleration Gst and the final target deceleration Gt based on the stepping stroke are both 0, and thus the target wheel cylinder pressure Pti of each wheel is also 0. Thus, an unnecessary braking force is reliably prevented from being applied to each wheel. Therefore, even if the master cylinder pressure rises due to the high pressure oil on the wheel cylinder side from the electromagnetic on-off valve 24L or 24R flowing back to the master cylinder 14, the target wheel cylinder of each wheel is caused by the increased master cylinder pressure. It is possible to reliably prevent the pressure Pti from being calculated to a high value.

(4) When a braking operation is performed after an abnormality has occurred in the linear valve on the front wheel during behavior control The braking operation is performed before a predetermined time has elapsed since the electromagnetic on-off valve 24L or 24R was opened. If so, an affirmative determination is made in steps 10 and 20, and the flag Fa is reset to 0 in step 110, whereby the wheel cylinder pressure based on the control mode (3), ie, the master cylinder pressure, is established. This completes the suppression of control. When a braking operation is performed after a predetermined time has elapsed since the electromagnetic on-off valve 24L or 24R is opened, a negative determination is made in step 10 and an affirmative determination is made in step 30. Done.

Therefore, in both cases where the braking operation is performed before the predetermined time elapses and when the braking operation is performed after the predetermined time elapses, an affirmative determination is made in step 130. Thus, in steps 140 to 170 and step 210, the wheel cylinder pressure Pi of each wheel is controlled based on the average value Pma of the master cylinder pressures Pm1 and Pm2 and the depression stroke St in the alternative mode when the linear valve is abnormal.

(5) When abnormality occurs in the front-wheel linear valve during behavior control during braking operation In this case as well, a negative determination is made in step 10 and an affirmative determination is made in step 30, so step 130 In step 140 to 170 and step 210, an affirmative determination is made in this way, and the wheel of each wheel based on the average value Pma of the master cylinder pressures Pm1 and Pm2 and the depression stroke St in the alternative mode when the linear valve is abnormal. The cylinder pressure Pi is controlled. Therefore, although the control of the wheel cylinder pressure based on the master cylinder pressure is not suppressed, in this case, since the master cylinder pressure is a relatively high pressure, the oil to the master cylinder is less than that during non-braking operation. There is little backflow.

  As understood from the above description, according to the illustrated embodiment 1, when an abnormality occurs in the front-wheel linear valve during behavior control during non-braking operation, the time when the electromagnetic on-off valve 24L or 24R is opened. Until a predetermined time elapses, the target wheel cylinder pressure Pti of each wheel is calculated based only on the stepping stroke St, and the target wheel cylinder pressure Pti of each wheel becomes 0. Therefore, an unnecessary braking force is applied to each wheel. Thus, the vehicle is surely prevented from being decelerated and braked unnecessarily, and a predetermined time has elapsed from the time when the electromagnetic on-off valve 24L or 24R is opened. When a braking operation is performed by the driver before the time elapses, the suppression of wheel cylinder pressure control based on the master cylinder pressure can be reliably ended.

  In particular, according to the first embodiment shown in the drawing, it is determined in step 20 whether or not the brake pedal 12 is depressed by the driver based on the depression stroke St. This is because the high pressure oil flows back to the master cylinder 14 and the master cylinder pressure rises as compared with the case where it is determined whether or not the brake pedal 12 is depressed based on the value Pma or the depression stroke St. Thus, it is possible to reliably reduce the possibility that the determination as to whether or not the brake pedal 12 is depressed is performed incorrectly.

  FIG. 5 is a flowchart showing the latter half of the braking force control routine in the second embodiment of the vehicle braking force control device according to the present invention applied to a vehicle equipped with a behavior control device as an automatic braking device. In FIG. 5, the same step number as the step number shown in FIG. 3 is assigned to the same step as the step shown in FIG.

  In this embodiment, steps 10 to 120 are executed in the same manner as in the first embodiment described above. However, when an affirmative determination is made in step 30 or when step 100 or 110 is completed, steps 10 to 120 are executed. 140 and 150 are executed. When step 150 is completed, it is determined in step 155 whether or not the flag Fa is 0 as in step 130 in the first embodiment, that is, whether the linear valve for the left and right front wheels is normal. If a positive determination is made, the process proceeds to step 160. If a negative determination is made, the process proceeds to step 185. In step 185, the weight α for the target deceleration Gpt is calculated from the map corresponding to the graph shown in FIG. The final target deceleration Gt is calculated as a weighted sum of the following, and then the routine proceeds to step 190.

  Thus, according to the illustrated second embodiment, when an abnormality occurs in the front-wheel linear valve during behavior control during non-braking operation, the weight α is reduced to reduce the master cylinder pressure relative to the target wheel cylinder pressure Pti. When the degree of contribution of the average value Pma is reduced and the braking operation is performed after an abnormality has occurred in the front wheel linear valve during behavior control, the reduction of the weight α is stopped and the target wheel cylinder pressure Pti is set to the master wheel cylinder pressure Pti. Since the calculation is based on the average value Pma of the cylinder pressure and the depression stroke St, it is possible to reliably prevent unnecessary braking force from being applied to each wheel, as in the case of the first embodiment described above. Can be reliably prevented from being decelerated and the braking operation is performed by the driver before a predetermined time has elapsed since the electromagnetic on-off valve 24L or 24R was opened. The The time can be reliably terminate inhibition of the control of the wheel cylinder pressure based on the master cylinder pressure.

  In particular, according to the illustrated embodiment 2, the weight α is variably set according to the target deceleration Gpt so as to decrease as the target deceleration Gpt increases. Therefore, the target wheel increases as the target deceleration Gpt based on the master cylinder pressure increases. The contribution degree of the average value Pma of the master cylinder pressure to the cylinder pressure Pti can be reduced, and the control of the wheel cylinder pressure based on the master cylinder pressure is suppressed only when there is a target deceleration Gpt based on the master cylinder pressure. be able to.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, when an abnormality occurs in any of the linear valves in a situation where the behavior control is performed by the electronic control unit 84, and the electromagnetic on-off valve 24L or 24R is opened, The target wheel cylinder pressure Pti of each wheel is calculated based on only the depression stroke St detected by the stroke sensor 70 for a predetermined time (Tofl, Tofr) from the time when the electromagnetic opening / closing valve 24L or 24R is opened. Although the time is constant, the predetermined time may be modified to be variably set according to the previous target wheel cylinder pressures Ptfl and Ptfr so that the higher the corresponding target wheel cylinder pressures Ptfl and Ptfr, the longer the predetermined time. .

  Further, in each of the above-described embodiments, when any one of the linear valves is abnormal in the situation where the behavior control is performed by the electronic control unit 84 and the electromagnetic on-off valve 24L or 24R is opened, In step 20, it is determined whether or not the brake pedal 12 is depressed by the driver based on the depression stroke St, but whether or not the brake pedal 12 is depressed by the driver is determined. May be modified to be performed based on the depression stroke St and the stop lamp switch.

  In each of the above-described embodiments, the target braking pressure Pti of each wheel is set to the average value Pma of the master cylinder pressures Pm1 and Pm2 and the depression amount St of the brake pedal as values indicating the amount of braking operation by the driver at normal times. Based on this, the driver's required deceleration Gt is calculated, and the target braking pressure Pti of each wheel is calculated based on the driver's required deceleration Gt. As long as the pressure Pti is calculated based on at least the master cylinder pressure, the braking force control itself may be executed in any manner known in the art.

  In each of the above-described embodiments, the automatic braking device that applies braking force to the wheels regardless of the driver's braking operation is a behavior control device, but the automatic braking device is a braking operation of the braking operator by the driver. As long as the pressure of the high pressure source is used to control the wheel cylinder pressure of a given wheel regardless of the vehicle, for example, the braking force is automatically applied to the wheel when there is a possibility that the vehicle may collide with a front obstacle. May be any automatic braking device such as an automatic braking device that automatically decelerates the vehicle.

  In each of the above-described embodiments, the pressure increase / reduction control valve for controlling the wheel cylinder pressure Pi of each wheel is composed of linear valves 50FL-50RR as pressure increase control valves and linear valves 60FL-60RR as pressure reduction control valves. However, these valves may be replaced with control valves having functions of increasing and decreasing pressure and holding.

  Furthermore, although the master cylinder pressure is detected by the two pressure sensors 66 and 68, the master cylinder pressure may be corrected so as to be detected by one pressure sensor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a hydraulic circuit of a first embodiment of a vehicle braking force control device according to the present invention applied to a vehicle equipped with a behavior control device as an automatic braking device. Example 1 It is a block diagram which shows the control system of the braking force control apparatus and behavior control apparatus in Example 1. FIG. Example 1 3 is a flowchart illustrating a first half of a braking force control routine according to the first embodiment. Example 1 3 is a flowchart illustrating a second half of a braking force control routine according to the first embodiment. Example 1 7 is a flowchart illustrating a second half of a braking force control routine according to the second embodiment. (Example 2) It is a graph which shows the relationship between the average value Pma of a master cylinder pressure, and target deceleration Gpt. (Examples 1 and 2) It is a graph which shows the relationship between the depression stroke St of a brake pedal, and the target deceleration Gst. (Examples 1 and 2) It is a graph which shows the relationship between the weight (alpha) with respect to the last final target deceleration Gtf and the target deceleration Gpt. (Examples 1 and 2) It is a graph which shows the relationship between target deceleration Gpt and weight (alpha). (Example 2)

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Brake apparatus 12 Brake pedal 14 Master cylinder 22FL-22RR Wheel cylinder 24F, 24R, 26 Electromagnetic on-off valve 50FL-50RR Linear valve 60FL-60RR Linear valve 66, 68 Pressure sensor 70 Stroke sensor 72, 74FL-74RR Pressure sensor 78, 84 Electronic control unit

Claims (6)

Each wheel has a communication control valve that controls the communication between the master cylinder and the wheel cylinder of each wheel, and each wheel uses the pressure of a high pressure source based on at least the master cylinder pressure with the communication control valve closed. In the vehicle braking force control device that controls the wheel cylinder pressure of the vehicle, the vehicle uses the pressure of the high pressure source to control the wheel cylinder pressure of a predetermined wheel regardless of the braking operation of the brake operator by the driver. When the communication control valve is switched from the closed state to the open state during the operation of the automatic braking device, it is detected that the braking operation is not performed on the braking operator. If it is detected by means, the at above its switching point within a predetermined time suppression control of the wheel cylinder pressure of each wheel based on the master cylinder pressure Braking force control apparatus for a vehicle, characterized by.   Each wheel has a communication control valve for controlling the communication between the master cylinder and the wheel cylinder of each wheel, and each wheel uses the pressure of a high pressure source based on at least the master cylinder pressure with the communication control valve closed. In the vehicle brake force control device that controls the wheel cylinder pressure of the vehicle, the vehicle uses the pressure of the high pressure source to control the wheel cylinder pressure of a predetermined wheel regardless of the braking operation of the brake operator by the driver. When the communication control valve is switched from the closed state to the open state during operation of the automatic braking device, each wheel based on the master cylinder pressure is operated until a braking operation is performed by the driver. A braking force control apparatus for a vehicle, characterized by suppressing control of wheel cylinder pressure. Brake operation detecting means for detecting a driver's braking operation with respect to the braking operator is provided, and the suppression of the control of the wheel cylinder pressure is detected by the braking operation detecting means that no braking operation is performed on the braking operator. The vehicle braking force control device according to claim 2 , wherein the vehicle braking force control device is performed when the vehicle braking is performed. The braking force control device calculates a target wheel cylinder pressure of each wheel based on at least the master cylinder pressure, and controls the wheel cylinder pressure of each wheel to become a corresponding target wheel cylinder pressure, and controls the wheel cylinder pressure. suppression vehicle braking force control apparatus according to any one of claims 1 to 3, characterized in that takes place when there is a control amount of the wheel cylinder pressure based on the target wheel cylinder pressure. The braking force control device calculates the target wheel cylinder pressure of each wheel based on the master cylinder pressure and the amount of operation displacement of the brake operator by the driver, and the wheel cylinder pressure of each wheel becomes the corresponding target wheel cylinder pressure. controlled, by reducing the contribution degree of the master cylinder pressure with respect to the target wheel cylinder pressure, in any one of claims 1 to 4, characterized in that to suppress control of the wheel cylinder pressure of each wheel based on the master cylinder pressure A braking force control device for a vehicle as described.   The braking force control device calculates the target wheel cylinder pressure of each wheel based only on the operation displacement amount of the brake operator by the driver, thereby reducing the contribution degree of the master cylinder pressure to the target wheel cylinder pressure to zero. 6. The braking force control device for a vehicle according to claim 5, wherein

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