JP2005041424A - Braking force control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent adding an unnecessary yaw moment on a vehicle or temporary adding unnecessary high braking force on the vehicle, when it becomes impossible to control the wheel cylinder pressure of right and left front wheels. <P>SOLUTION: When one front wheel is abnormal, if the other front wheel becomes also abnormal (S105, 130), a solenoid opening/closing valve 24L or 24R of the second abnormal wheel is opened. Until specified time To has passed since a point of time when the second abnormal wheel becomes abnormal (S150), or until the wheel cylinder pressure of the right and left front wheels comes to be actually equal to master cylinder pressure (S155), target wheel cylinder pressure of right and left rear wheels is set to be the wheel cylinder pressure (S175)of right and left opposite side front wheels, or pressure (S170, 1q90) detected by a normal pressure sensor, or an average value Pma (S185) of the master cylinder pressure, according to situations of the pressure sensors 74FL, 74FR. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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, and the target wheel cylinder pressure of each wheel is calculated to be higher than the master cylinder pressure based on the master cylinder pressure and the brake pedal depression stroke. 2. Description of the Related Art A braking force control device that controls a wheel pressure increasing / decreasing control valve is conventionally known.
JP 2002-316630 A

  In general, in the braking force control apparatus as described above, for example, if an abnormality occurs in one of the left and right front wheels, and the wheel cylinder pressure cannot be controlled, the communication control valve is opened for the wheel, The wheel cylinder of the wheel is connected to the master cylinder, and the wheel cylinder pressure of the wheel is the same as the master cylinder pressure.

  However, since the wheel cylinder pressure is controlled to be higher than the master cylinder pressure in accordance with the amount of braking operation by the driver with the communication control valve closed, the other wheels have the wheel cylinder pressure of the left and right front wheels. The difference increases and an unnecessary yaw moment acts on the vehicle due to the difference in braking force between the left and right front wheels.

  In addition, when the wheel cylinder pressure of one of the left and right front wheels cannot be controlled, and the communication control valve for that wheel is opened, the wheel on the opposite side to that wheel also has an abnormality in the pressure increase / decrease control valve, for example. If it becomes impossible to control the wheel cylinder pressure, the communication control valve for that wheel is also opened, so that the high-pressure hydraulic fluid on the wheel cylinder side from the communication control valve flows back to the master cylinder via the communication control valve, and the master cylinder The pressure rises rapidly and instantaneously.

  Therefore, an unnecessarily high target wheel cylinder pressure is calculated for the left and right rear wheels based on the increased master cylinder pressure, and the left and right rear wheels are controlled so that the wheel cylinder pressure of the left and right rear wheels becomes the target wheel cylinder pressure. The braking force is temporarily controlled to be unnecessarily high, and this problem is particularly noticeable 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. The present invention has been made in view of the above-described problems when the wheel cylinder pressure cannot be controlled so as to become the target wheel cylinder pressure. The main problem of the present invention is that the wheel cylinder pressure is the target wheel cylinder pressure. Reduces the impact when the cylinder pressure can no longer be controlled, preventing unnecessary yaw moment from acting on the vehicle and temporarily preventing unnecessary high braking force from acting on the left and right rear wheels That is.

  According to the present invention, the main problem described above is based on the configuration of claim 1, that is, the communication control valve for controlling the communication between the master cylinder and the wheel cylinder of each wheel, and based on the braking operation amount of the driver. The target wheel cylinder pressure of the left and right rear wheels is calculated to be higher than the master cylinder pressure, and the pressure increase / decrease control valve of each wheel is controlled 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 each wheel to the target wheel cylinder pressure using the pressure of the pressure source, it is impossible to control the wheel cylinder pressure of one of the left and right front wheels. The abnormal wheel communication control valve is opened, and the wheel cylinder pressure of the rear wheel opposite to the abnormal wheel is substantially the same as the wheel cylinder pressure of the abnormal wheel. When the wheel cylinder pressure of the wheel on the opposite side to the abnormal wheel cannot be controlled while controlling to the pressure, the communication control valve of the second abnormal wheel is opened, and the second This is achieved by a braking force control device for a vehicle, wherein the wheel cylinder pressure of the rear wheel opposite to the abnormal wheel is controlled to be substantially the same as the wheel cylinder pressure of the second abnormal wheel. .

  According to the present invention, in order to effectively achieve the main problems described above, the wheel cylinder pressures of the left and right front wheels are detected and the average value of the wheel cylinder pressures of the left and right front wheels is determined. It is comprised so that it may be set as the target wheel cylinder pressure of a left-right rear wheel (structure of Claim 2).

  According to the present invention, in order to effectively achieve the main problems described above, the wheel cylinder pressures of the left and right front wheels are detected and the wheel cylinder pressures of the left and right front wheels are respectively detected. Is the target wheel cylinder pressure for the left and right rear wheels.

  According to the present invention, in order to effectively achieve the main problem described above, the wheel cylinder pressure of any of the left and right front wheels is detected and the detected wheel cylinder pressure is detected. The wheel cylinder pressure of the left and right rear wheels is controlled as the target wheel cylinder pressure (configuration of claim 4).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the master cylinder pressure is detected, and the detected master cylinder pressure is determined as the target wheel cylinder pressure. It is comprised so that the wheel cylinder pressure of a rear-wheel may be controlled (structure of Claim 5).

  According to the present invention, in order to effectively achieve the above-mentioned main problems, the wheel cylinder pressures of the left and right front wheels in the control process of claims 1 to 5 in the configuration of claims 1 to 5 described above. Is substantially the same as the master cylinder pressure, the left and right rear wheel target wheel cylinder pressures are calculated to be higher than the master cylinder pressure based on the driver's braking operation amount, and the left and right rear wheel wheel cylinder pressures are calculated. Is configured to be controlled based on the target wheel cylinder pressure.

  According to the configuration of claim 1, the wheel cylinder pressure of one of the left and right front wheels cannot be controlled and the communication control valve for the abnormal wheel is opened, and the wheel cylinder pressure of the rear wheel on the opposite side to the abnormal wheel is opened. Is controlled to substantially the same pressure as the wheel cylinder pressure of the abnormal wheel, and when the wheel cylinder pressure of the wheel on the opposite side to the abnormal wheel cannot be controlled, the second abnormal wheel The communication control valve is opened, and the wheel cylinder pressure of the rear wheel opposite to the second abnormal wheel is controlled to be substantially the same as the wheel cylinder pressure of the second abnormal wheel. When the braking force of the two pairs of wheels opposite to each other has substantially the same value, and therefore the wheel cylinder pressure of the left and right front wheels cannot be controlled to the target wheel cylinder pressure, Running state of things and thereby during vehicle braking acts unnecessary yaw moment to the vehicle due to the difference can be reliably prevented from being unstable.

  According to the configuration of the second aspect, the wheel cylinder pressure of the left and right front wheels is detected, and the average value of the wheel cylinder pressure of the left and right front wheels is set as the target wheel cylinder pressure of the left and right rear wheels. When the pressure is controlled to the average value of the wheel cylinder pressure of the left and right front wheels, and therefore the wheel cylinder pressure of the left and right front wheels cannot be controlled to the target wheel cylinder pressure, the vehicle is not effective due to the difference in braking force between the left and right rear wheels. It is possible to reliably prevent the necessary yaw moment from acting and the unstable running state during braking of the vehicle.

  Further, according to the configuration of the third aspect, the wheel cylinder pressures of the left and right front wheels are detected, and the wheel cylinder pressures of the front wheels on the left and right opposite sides are set as the target wheel cylinder pressures of the left and right rear wheels. When the braking force of the two wheels of the two wheels becomes the same value, and the wheel cylinder pressure of the left and right front wheels cannot be controlled to the target wheel cylinder pressure, the vehicle is caused by the difference in braking force between the left and right front and rear wheels. Thus, it is possible to reliably prevent an unnecessary yaw moment from acting on the vehicle and an unstable driving state during braking of the vehicle.

  According to the configuration of the fourth aspect, the wheel cylinder pressure of any of the left and right front wheels is detected, and the wheel cylinder pressure of the left and right rear wheels is controlled using the detected wheel cylinder pressure as the target wheel cylinder pressure. Even when an abnormality occurs in the means for detecting the wheel cylinder pressure of the front wheel or the right front wheel and the wheel cylinder pressure of the wheel cannot be controlled to the target wheel cylinder pressure, the vehicle is caused by the difference in braking force between the left and right rear wheels. Thus, it is possible to reliably prevent an unnecessary yaw moment from acting on the vehicle and an unstable driving state during braking of the vehicle.

  According to the fifth aspect of the present invention, the master cylinder pressure is detected, and the wheel cylinder pressure of the left and right rear wheels is controlled using the detected master cylinder pressure as the target wheel cylinder pressure. Even if the detection means becomes abnormal and the wheel cylinder pressure of the left and right front wheels cannot be controlled to the target wheel cylinder pressure, an unnecessary yaw moment acts on the vehicle due to the difference in braking force between the left and right rear wheels. This makes it possible to reliably prevent the running state during braking of the vehicle from becoming unstable.

  Further, according to the configuration of the sixth aspect, when the wheel cylinder pressure of the left and right front wheels becomes substantially the same as the master cylinder pressure in the control process of the first to fifth aspects, the braking operation amount of the driver is increased. Based on this, the target wheel cylinder pressure of the left and right rear wheels is calculated to be higher than the master cylinder pressure, and the wheel cylinder pressure of the left and right rear wheels is controlled to become the target wheel cylinder pressure. The target wheel cylinder that is calculated to a high value based on the master cylinder pressure that is increased when the valve is opened and the high-pressure working fluid on the wheel cylinder side flows back to the master cylinder from the second abnormal wheel communication control valve The pressure of the wheel cylinders on the left and right rear wheels is controlled so that the pressure becomes the same, and as a result, the braking force of the entire vehicle may temporarily become excessively high. Can be reliably prevented, and the possibility that the braking force of the entire vehicle will be insufficient at the stage where the braking force of the entire vehicle is no longer temporarily excessively high can be effectively reduced. it can.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, when the wheel cylinder pressure of the left and right front wheels is detected and the wheel cylinder pressure of one of the left and right front wheels cannot be controlled in the configuration of the first to sixth aspects, The abnormal wheel communication control valve is opened, and the wheel cylinder pressure of the rear wheel on the opposite side to the abnormal wheel is controlled using the wheel cylinder pressure of the abnormal wheel as the target wheel cylinder pressure (preferred aspect 1).

  According to another preferred embodiment of the present invention, when the wheel cylinder pressure of the left and right front wheels is detected and the wheel cylinder pressure of one of the left and right front wheels cannot be controlled in the configuration of the above-described first to sixth aspects. The control valve for the abnormal wheel is opened, and the wheel cylinder pressure of the wheel on the opposite side to the abnormal wheel is set as the target wheel cylinder pressure to control the wheel cylinder pressure on the rear wheel on the opposite side of the abnormal wheel. (Preferred aspect 2)

  According to another preferred embodiment of the present invention, when the master cylinder pressure is detected and the wheel cylinder pressure of one of the left and right front wheels cannot be controlled in the configuration of the first to sixth aspects, the abnormality is detected. Open the wheel communication control valve and use the detected master cylinder pressure as the target wheel cylinder pressure and the wheel cylinder pressure of the wheel on the opposite side to the abnormal wheel as the target wheel cylinder pressure. It is configured to control the wheel cylinder pressure of the wheel (preferred aspect 3).

  According to another preferred aspect of the present invention, in the configuration of claim 2, the control of claim 2 is performed when the communication control valve or the pressure increasing / reducing control valve for the left and right front wheels is abnormal. (Preferred embodiment 4)

  According to another preferred aspect of the present invention, in the configuration of claim 3, the control of claim 3 is performed when the communication control valve or the pressure increasing / reducing control valve for the left and right front wheels is abnormal. (Preferred embodiment 5)

  According to another preferred aspect of the present invention, in the configuration of claim 4, when the means for detecting the wheel cylinder pressure of the left front wheel or the right front wheel is abnormal, the control of claim 4 is performed. Constructed (preferred embodiment 6).

  According to another preferred embodiment of the present invention, in the configuration of claim 5, the control of claim 5 is performed when the means for detecting the wheel cylinder pressure of the left and right front wheels is abnormal. (Preferred embodiment 7).

  According to another preferred aspect of the present invention, in the configuration according to any one of claims 1 to 6, when a predetermined time elapses from the time when the second abnormal wheel becomes abnormal, the amount of braking operation by the driver. Based on the above, the target wheel cylinder pressure of the left and right rear wheels is calculated to be higher than the master cylinder pressure, and the wheel cylinder pressure of the left and right rear wheels is controlled to become the target wheel cylinder pressure (preferred aspect 8).

  According to another preferred embodiment of the present invention, in the constructions of claims 1 to 6, the communication control valve is configured to be a normally open electromagnetic on-off valve (preferred embodiment 9).

  According to another preferred 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. (Preferred embodiment 10).

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

  FIG. 1 is a schematic configuration diagram showing a hydraulic circuit of an embodiment of a vehicle braking force control apparatus according to the present invention and a block diagram showing a control system. 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 open / close valves 24L and 24R, the electromagnetic open / close valve 26, the electric motor 34, the linear valves 50FL to 50RR, and the linear valves 60FL to 60RR are controlled by an electronic control unit 78. 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 flowcharts shown in FIGS. 2 and 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 valve 24L. And 24R are closed, and the target deceleration Gt of the vehicle is calculated based on the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 and the depression stroke St detected by the stroke sensor 70 in that state. Based on the target deceleration Gt, the target wheel cylinder pressure Pti (i = fl, fr, rl, rr) of each wheel is calculated to be higher than the master cylinder pressures Pm1, Pm2, and the braking pressure Pi of each wheel is calculated as the target wheel. The linear valves 50FL to 50RR and 60FL to 60RR are controlled so as to be the cylinder pressure Pti.

  As will be understood from the above description, the microcomputer 80 calculates the target wheel cylinder pressure of each wheel to a value higher than the master cylinder pressures Pm1 and Pm2 based on the braking operation amount of the driver, and the electromagnetic opening / closing valves 24L and 24R, The valve 26L, the motor 34, the linear valves 50FL to 50RR, the linear valves 60FL to 60RR, the electronic control device 78, the pressure sensor 66, etc. The control means is configured to control the linear valves 50FL to 50RR and the linear valves 60FL to 60RR so that the wheel cylinder pressure of each wheel becomes the corresponding target wheel cylinder pressure with the valve 24R closed.

  In the illustrated embodiment, microcomputer 80 determines whether the wheel cylinder pressure for each wheel is in a condition that can be controlled to the corresponding target wheel cylinder pressure according to self-diagnostic routines known in the art. For example, a pressure sensor 74FL that detects the pressures Pfl and Pfr in the wheel cylinders 22FL and 22FR, respectively, that is, an abnormality in which the electromagnetic on-off valves 24L and 24R cannot be closed, an abnormality in which the linear valves 60FL and 60FR cannot be closed, respectively. When an abnormality occurs in which the wheel cylinder pressure of the left front wheel or the right front wheel cannot be controlled to the corresponding target wheel cylinder pressure, such as the abnormality of 74FR, the linear valves 60FL and 60FR of the wheel are opened, and the wheel of the wheel The cylinders 22FL, 22FR and the master cylinder 14 are communicated with each other, and in principle, the wheel series The said wheels da pressure as the target wheel cylinder pressure to control the wheel cylinder pressure of the right and left rear wheels opposite.

  In the situation where the microcomputer 80 has an abnormality in which the wheel cylinder pressure of the left front wheel or the right front wheel cannot be controlled to the corresponding target wheel cylinder pressure, the target wheel corresponding to the wheel cylinder pressure corresponding to the other of the left and right front wheels is generated. When an uncontrollable abnormality occurs in the cylinder pressure, in principle, the wheel cylinder pressure of the rear wheel opposite to the second wheel is controlled using the wheel cylinder pressure of the second abnormal wheel as the target wheel cylinder pressure. .

  Further, in the process in which the left and right front wheels are abnormal and the microcomputer 80 performs the above-described control, if the wheel cylinder pressure of the left and right front wheels is substantially the same as the master cylinder pressure, or the second abnormal wheel is When a predetermined time elapses from the time of the abnormality, the target wheel cylinder pressures Ptrl and Ptrr for the left and right rear wheels are calculated to be higher than the master cylinder pressures Pm1 and Pm2 based on the amount of braking operation performed by the driver. The wheel cylinder pressures Prl and Prr are controlled to be the target wheel cylinder pressures Ptrl and Ptrr, respectively.

  Next, the braking force control in the embodiment will be described with reference to the flowcharts shown in FIGS. 2 and 3 is started when the microcomputer 80 is started, and is repeatedly executed every predetermined time.

  First, in step 10, 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 20, and if an affirmative determination is made, the process proceeds to step 30. 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 20, the electromagnetic on-off valve 26 is closed, and the electromagnetic on-off valves 24L and 24R are opened, whereby the communication between the master cylinder 14 and the wet stroke simulator 28 is shut off and the master cylinder 14 is opened. And wheel cylinders 22FL, 22FR, 22RL, and 22RR of each wheel are connected in communication. In step 30, the electromagnetic on-off valve 26 is opened or maintained, and the electromagnetic on-off valves 24L and 24R are closed or maintained, whereby the master cylinder 14 and the wet stroke are maintained. The simulator 28 is connected in communication, and communication between the master cylinder 14 and the wheel cylinders 22FL, 22FR, 22RL, and 22RR of each wheel is blocked.

  In step 40, 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. 4 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 50, 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 60, the weight α (0 ≦ α ≦ 1) for the target deceleration Gpt is calculated from the map corresponding to the graph shown in FIG. 6 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 70, 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 100, it is determined whether or not there is an abnormality in which the wheel cylinder pressure of the left and right front wheels cannot be controlled to the corresponding target wheel cylinder pressure Pti according to the routine shown in FIG. The target wheel cylinder pressure Pti is corrected in accordance with the determination result, and in step 200, control is performed by hydraulic feedback so that the wheel cylinder pressure Pi of each wheel becomes the corresponding target wheel cylinder pressure Pti.

  Next, the abnormality determination in step 100 and the target wheel cylinder pressure Pti correction routine will be described with reference to the flowchart shown in FIG.

  In step 105, it is determined whether or not the left front wheel is abnormal, that is, whether or not the wheel cylinder pressure of the left front wheel cannot be controlled to the target wheel cylinder pressure Ptfl. When a positive determination is made, the process proceeds to step 130, and when a negative determination is made, the process proceeds to step 110.

  In step 110, it is determined whether or not the right front wheel is abnormal, that is, whether or not the wheel cylinder pressure of the right front wheel cannot be controlled to the target wheel cylinder pressure Ptfl. When a negative determination is made, the process proceeds directly to step 200, and when an affirmative determination is made, the process proceeds to step 115.

  In step 115, it is determined whether or not the pressure sensor 74FR for the right front wheel is abnormal. If an affirmative determination is made in step 120, the target wheel cylinder pressure Ptrl for the left rear wheel is set to the value for the left front wheel. When the wheel cylinder pressure Pfl is set and a negative determination is made, at step 125, the target wheel cylinder pressure Ptrl for the left rear wheel is set to the wheel cylinder pressure Pfr for the right front wheel.

  In step 130, it is determined whether the right front wheel is abnormal as in step 110. If an affirmative determination is made, the process proceeds to step 150. If a negative determination is made, the process proceeds to step 135. .

  In step 135, it is determined whether or not the pressure sensor 74FL for the left front wheel is abnormal. If an affirmative determination is made, in step 140, the target wheel cylinder pressure Ptrr for the right rear wheel is set to the value for the right front wheel. When the wheel cylinder pressure Pfr is set and a negative determination is made, in step 145, the target wheel cylinder pressure Ptrr for the right rear wheel is set to the target wheel cylinder pressure Pfl for the left front wheel.

  In step 150, the elapsed time T from the time when the first affirmative determination was made in step 105 or 130 for the second abnormal wheel, that is, the wheel that became abnormal later among the left and right front wheels, is the reference value To ( If a positive determination is made, the process proceeds directly to step 200. If a negative determination is made, the process proceeds to step 155. The reference value To is a master cylinder caused by the high-pressure oil on the wheel cylinder side flowing back to the master cylinder 14 from the electromagnetic on-off valve when the electromagnetic on-off valve 24L or 24R of the second abnormal wheel is opened. It is set to the time when the instantaneous increase in pressure is settled.

  In step 155, for example, the absolute value of the deviation ΔPfl between the wheel cylinder pressure Pfl of the left front wheel and the average value Pma of the master cylinder pressure is not more than a reference value ΔPo (positive constant) and the wheel cylinder pressure Pfr of the right front wheel is By determining whether or not the absolute value of the deviation ΔPfr from the average value Pma of the master cylinder pressure is equal to or less than the reference value ΔPo, the wheel cylinder pressure Pfl of the left front wheel is substantially equal to the average value Pma of the master cylinder pressure and the right front wheel It is determined whether or not the wheel cylinder pressure Pfr is substantially equal to the average value Pma of the master cylinder pressure. If an affirmative determination is made, the process proceeds directly to step 200, and if a negative determination is made, the process proceeds to step 160.

  In step 160, it is determined whether or not the left front wheel pressure sensor 74FL is abnormal. If an affirmative determination is made, the process proceeds to step 180. If a negative determination is made, the process proceeds to step 165.

  In step 165, it is determined whether or not the pressure sensor 74FR for the right front wheel is abnormal. If an affirmative determination is made in step 170, the target wheel cylinder pressure Ptrl for the left rear wheel and the right rear wheel are determined. The target wheel cylinder pressure Ptrr of the left front wheel is set to the wheel cylinder pressure Pfl of the left front wheel, and when a negative determination is made, the target wheel cylinder pressure Ptrl of the left rear wheel is set to the wheel cylinder pressure Pfr of the right front wheel. In addition, the target wheel cylinder pressure Ptrr for the right rear wheel is set to the wheel cylinder pressure Pfl for the left front wheel.

  In step 180, it is determined whether or not the pressure sensor 74FR for the right front wheel is abnormal. If an affirmative determination is made, in step 185, the target wheel cylinder pressure Ptrl for the left rear wheel and the right rear wheel are determined. When the target wheel cylinder pressure Ptrr of the left rear wheel is set to the average value Pma of the master cylinder pressure and a negative determination is made, the target wheel cylinder pressure Ptrl of the left rear wheel and the target wheel cylinder pressure Ptrr of the right rear wheel are determined in step 190. The wheel cylinder pressure Pfr for the right front wheel is set.

  Thus, according to the illustrated embodiment, when the braking operation is performed by the driver under the condition that all the wheels are normal, an affirmative determination is made in step 10, and the driver's determination is made in steps 40 to 70. The target deceleration Gt of the vehicle is calculated based on the amount of braking operation, the target wheel cylinder pressure Pti of each wheel is calculated based on the target deceleration Gt of the vehicle, and a negative determination is made in steps 105 and 110 in FIG. In step 200, the brake valve is 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

  On the other hand, when the left front wheel becomes abnormal, the electromagnetic opening / closing valve 24L is opened, and an affirmative determination is made in step 105 of FIG. 3, and a negative determination is made in step 130. When the pressure sensor 74FL is normal, a negative determination is made in step 130, and in step 145, the target wheel cylinder pressure Ptrr for the right rear wheel is set to the wheel cylinder pressure Pfl for the left front wheel, and the pressure sensor 74FL is If there is an abnormality, an affirmative determination is made at step 130, and at step 140, the target wheel cylinder pressure Ptrr for the right rear wheel is set to the wheel cylinder pressure Pfr for the right front wheel, and thereby the braking force difference between the left and right front and rear wheels. Is prevented from becoming large.

  Similarly, when the right front wheel becomes abnormal, the electromagnetic on-off valve 24R is opened, and a negative determination is made at step 105 in FIG. 3, and an affirmative determination is made at step 110. When the pressure sensor 74FR is normal, a negative determination is made in step 115, and in step 125, the target wheel cylinder pressure Ptrl for the left rear wheel is set to the wheel cylinder pressure Pfr for the right front wheel, and the pressure sensor 74FR is If there is an abnormality, an affirmative determination is made in step 115, and in step 120, the target wheel cylinder pressure Ptrl for the left rear wheel is set to the wheel cylinder pressure Pfl for the left front wheel, whereby the braking force difference between the left and right front and rear wheels Is prevented from becoming large.

  When the right front wheel becomes abnormal in a situation where the left front wheel is abnormal, the electromagnetic on / off valve 24R is also opened. When the right front wheel becomes abnormal in a situation where the right front wheel is abnormal, the electromagnetic on / off valve 24L is also opened. In either case, an affirmative determination is made in steps 105 and 130 in FIG. 3, and a predetermined time To has elapsed since the right front wheel or the left front wheel, which is the second abnormal wheel, becomes abnormal. If the wheel cylinder pressure of the left and right front wheels is not substantially equal to the master cylinder pressure, a negative determination is made in steps 150 and 155.

  When the left and right front wheel pressure sensors 74FL and 74FR are normal, a negative determination is made in steps 160 and 165, and in step 175, the target wheel cylinder pressures Ptrl and Ptrr for the left and right rear wheels are set to the right front wheel and the left, respectively. The wheel cylinder pressures Pfr and Pfl of the front wheels are set, thereby reliably preventing a difference in braking force between the left and right front and rear wheels.

  When the pressure sensor 74FL for the left front wheel is normal and the pressure sensor 74FR for the right front wheel is abnormal, a negative determination is made at step 160 and an affirmative determination is made at step 165. The target wheel cylinder pressures Ptrl and Ptrr for the left and right rear wheels are set to the wheel cylinder pressure Pfl for the left front wheel, thereby preventing an increase in the braking force difference between the left and right front and rear wheels.

  Conversely, when the pressure sensor 74FL for the left front wheel is abnormal and the pressure sensor 74FR for the right front wheel is normal, an affirmative determination is made at step 160 and a negative determination is made at step 180. Thus, the target wheel cylinder pressures Ptrl and Ptrr for the left and right rear wheels are set to the wheel cylinder pressure Pfr for the right front wheel, thereby preventing an increase in the braking force difference between the left and right front and rear wheels.

  Further, when both the left front wheel pressure sensor 74FL and the right front wheel pressure sensor 74FR are abnormal, an affirmative determination is made in steps 160 and 180, and in step 185, the target wheel cylinder pressure Ptrl and the left and right rear wheels are determined. Ptrr is set to the average value Pma of the master cylinder pressure, thereby reliably preventing a difference in braking force between the left and right front and rear wheels.

  Therefore, not only when one of the left and right front wheels becomes abnormal, but also when one of the left and right front wheels becomes abnormal and the other of the left and right front wheels also becomes abnormal, the difference in braking force between the left and right front and rear wheels becomes large. It is possible to reliably prevent unnecessary yaw moment from acting on the vehicle due to the difference in braking force between the left and right front and rear wheels, and thereby preventing the running state during braking of the vehicle from becoming unstable. it can.

  In particular, according to the illustrated embodiment, even when the left and right front wheels become abnormal, if the left and right front wheel pressure sensors 74FL and 74FR are normal, the wheel cylinder pressure of the left and right rear wheels is When one of the left and right front wheel pressure sensors 74FL and 74FR is normal, the wheel cylinder pressure of the left and right rear wheels is controlled to be the pressure detected by the pressure sensor. If both the left and right front wheel pressure sensors 74FL and 74FR are abnormal, the wheel cylinder pressure of the left and right rear wheels is controlled to be the average value Pma of the master cylinder pressure. Thus, the wheel cylinder pressure of the left and right rear wheels can be appropriately controlled.

  Further, according to the illustrated embodiment, when the wheel cylinder pressure of the left and right front wheels becomes substantially the same as the master cylinder pressure, or when a predetermined time has elapsed since the second abnormal wheel became abnormal, The target wheel cylinder pressures Ptrl and Ptrr for the left and right rear wheels are calculated to be higher than the master cylinder pressures Pm1 and Pm2 based on the braking operation amount of the user, and the wheel cylinder pressures Prl and Prr for the left and right rear wheels are respectively set to the target wheel cylinder pressure Ptrl. , Ptrr is controlled so that the second abnormal wheel communication control valve electromagnetic open / close valve 24L or 24R is opened, and the higher pressure oil on the wheel cylinder side than the second abnormal wheel communication control valve is the master. Wheels for the left and right rear wheels so that the target wheel cylinder pressure is calculated to a high value based on the master cylinder pressure that has increased by backflowing to the cylinder 14. It can be reliably prevented that the cylinder pressure is controlled and the braking force of the entire vehicle temporarily increases excessively due to this, and the braking force of the entire vehicle temporarily increases excessively. It is possible to effectively reduce the possibility that the braking force of the entire vehicle will be insufficient at the stage where the fear disappears.

  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 the above-described embodiment, when one of the pressure sensors 74FL or 74FR for the left and right front wheels is abnormal, the pressure detected by the normal pressure sensor for the wheel cylinder pressure for the left and right rear wheels in step 170 or 190. However, in this case as well, the wheel cylinder pressure of the left and right rear wheels may be controlled to be the average value Pma of the master cylinder pressure.

  Further, in the above-described embodiment, until it is determined in step 150 that a predetermined time has elapsed from the time when the second abnormal wheel becomes abnormal, or in step 155, the wheel cylinder of the left front wheel. Steps 160 to 190 are executed until it is determined that the pressure Pfl is approximately equal to the average value Pma of the master cylinder pressure and the wheel cylinder pressure Pfr of the right front wheel is approximately equal to the average value Pma of the master cylinder pressure. However, the determination of either step 150 or 1550 may be omitted.

  In the above-described embodiment, the target braking pressure Pti of each wheel is operated based on the average value Pma of the master cylinder pressures Pm1 and Pm2 as a value indicating the amount of braking operation by the driver and the depression amount St of the brake pedal. 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, but the control of the braking force itself forms the gist of the present invention. Rather, it may be performed in any manner known in the art.

  In the above-described embodiment, the pressure increasing / reducing control valve for controlling the wheel cylinder pressure Pi of each wheel is composed of the linear valves 50FL to 50RR as pressure increasing control valves and the linear valves 60FL to 60RR as pressure reducing 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.

1 is a schematic configuration diagram showing a hydraulic circuit of an embodiment of a vehicle braking force control apparatus according to the present invention and a block diagram showing a control system. It is a general flowchart which shows the braking force control routine in an Example. It is a flowchart which shows abnormality determination of the braking force control in an Example, and a target wheel cylinder pressure correction routine. It is a graph which shows the relationship between the average value Pma of a master cylinder pressure, and target deceleration Gpt. It is a graph which shows the relationship between the depression stroke St of a brake pedal, and the target deceleration Gst. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Brake device 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 Electronic control apparatus

Claims (6)

  It has a communication control valve that controls the communication between the master cylinder and the wheel cylinder of each wheel, and calculates the target wheel cylinder pressure of the left and right rear wheels to a value higher than the master cylinder pressure based on the braking operation amount of the driver, By controlling the pressure increasing / reducing control valve of each wheel based on at least the master cylinder pressure with the communication control valve closed, the wheel cylinder pressure of each wheel is adjusted to the target wheel cylinder using the pressure of the high pressure source. In a braking force control device for a vehicle that controls pressure so that one wheel cylinder pressure of one of the left and right front wheels cannot be controlled, the communication control valve for the abnormal wheel is opened, and the right and left sides are opposite to the abnormal wheel. When the wheel cylinder pressure of the rear wheel is controlled to be substantially the same as the wheel cylinder pressure of the abnormal wheel, the vehicle on the opposite side to the abnormal wheel When it becomes impossible to control the wheel cylinder pressure of the second abnormal wheel, the communication control valve of the second abnormal wheel is opened, and the wheel cylinder pressure of the rear wheel on the side opposite to the second abnormal wheel is set to the second abnormal wheel. A braking force control device for a vehicle, wherein the pressure is controlled to be substantially the same as a wheel cylinder pressure of an abnormal wheel.   2. The vehicle braking force control device according to claim 1, wherein wheel cylinder pressures of the left and right front wheels are detected, and an average value of the wheel cylinder pressures of the left and right front wheels is set as a target wheel cylinder pressure of the left and right rear wheels.   2. The vehicle braking force control device according to claim 1, wherein the wheel cylinder pressure of the left and right front wheels is detected, and the wheel cylinder pressure of the front wheel on the opposite side is set as the target wheel cylinder pressure of the left and right rear wheels.   2. The vehicle braking force according to claim 1, wherein the wheel cylinder pressure of any of the left and right front wheels is detected, and the wheel cylinder pressure of the left and right rear wheels is controlled using the detected wheel cylinder pressure as a target wheel cylinder pressure. Control device.   2. The vehicle braking force control device according to claim 1, wherein a master cylinder pressure is detected, and the wheel cylinder pressure of the left and right rear wheels is controlled using the detected master cylinder pressure as a target wheel cylinder pressure. When the wheel cylinder pressure of the left and right front wheels is substantially the same as the master cylinder pressure in the control process of claims 1 to 5, the target wheel cylinder pressure of the left and right rear wheels is set based on the braking operation amount of the driver. 6. The vehicle braking force control apparatus according to claim 1, wherein a control is performed so that the wheel cylinder pressure of the left and right rear wheels becomes a target wheel cylinder pressure by calculating a value higher than the master cylinder pressure.

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