JP3956915B2 - 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.

As one of braking force control devices for vehicles such as automobiles, for example, as described in the following Patent Document 1 relating to the application of the present applicant, a pressure increasing solenoid valve and a wheel cylinder pressure for increasing the wheel cylinder pressure are disclosed. A pressure reducing solenoid valve for reducing the pressure, and calculating a target wheel cylinder pressure based on a driver's braking operation amount, and a pressure increasing solenoid valve and a pressure reducing solenoid valve so that the wheel cylinder pressure becomes the target wheel cylinder pressure. 2. Description of the Related Art A braking force control device for controlling is conventionally known.
JP-A-11-235975

  In the braking force control apparatus as described above, generally, the pressure increasing and pressure reducing solenoid valves are normally closed solenoid valves, but the normally closed solenoid valves are different from the normally open solenoid valves. Since it is expensive, it is conceivable that at least some of the wheels, for example, the right and left rear wheel pressure reducing solenoid valves are normally open solenoid valves in order to reduce the cost of the braking force control device.

  When the pressure reducing solenoid valve is a normally open type solenoid valve, when the wheel cylinder pressure is to be increased or maintained, a control current is supplied to the normally open type pressure reducing solenoid valve, thereby reducing the pressure reducing solenoid valve. The valve must be closed. For this reason, if the normally open pressure reducing solenoid valve does not become completely closed due to some reason, the working fluid leaks from the wheel cylinder through the incompletely closed pressure reducing solenoid valve. Even if a control current of a predetermined pressure increase is supplied to the solenoid valve for pressure, the wheel cylinder pressure cannot be increased with the original pressure increase gradient, the maximum value of the wheel cylinder pressure is also limited, and further There is a high possibility that an excessive control current is supplied to the solenoid valve.

  Therefore, when the pressure reducing solenoid valve is a normally open solenoid valve, preliminary measures are taken to cope with the situation where the normally open pressure reducing solenoid valve is not completely closed. It is preferable that

  The present invention includes a solenoid valve for pressure increase and a solenoid valve for pressure reduction, calculates a target wheel cylinder pressure based on a braking operation amount of the driver, and increases the pressure solenoid valve and pressure reduction so that the wheel cylinder pressure becomes the target wheel cylinder pressure. In a braking force control device that controls a solenoid valve for use, when the solenoid valve for pressure reduction is a normally open solenoid valve, the normally open type solenoid valve for pressure reduction is not completely closed as described above. The main problem of the present invention is that the normally open type pressure reducing solenoid valve is not in a completely closed state. When this occurs, the normally open pressure reducing solenoid valve is not completely closed by changing the control of the pressure increasing solenoid valve according to the incomplete closing state of the normally open pressure reducing solenoid valve. If a situation arises, It is to perform the control of Rushirinda pressure.

  According to the present invention, the main problems described above are a normally closed solenoid valve that operates according to the supplied control current and increases the wheel cylinder pressure, and the wheel cylinder pressure that operates according to the supplied control current. A normally open solenoid valve for reducing the pressure of the vehicle, and controlling the wheel cylinder pressure to a target wheel cylinder pressure by controlling the normally closed solenoid valve and the normally open solenoid valve. An upper limit value of a target wheel cylinder pressure is set according to a control current supplied to the normally open solenoid valve when the normally open solenoid valve is to be fully closed. A braking force control device for a vehicle (configuration of claim 1), characterized in that the normally closed solenoid valve and the normally open solenoid valve are controlled by limiting the pressure to the upper limit value or less. Depending on the control current A normally-closed solenoid valve that increases the wheel cylinder pressure, and a normally-open solenoid valve that operates according to the supplied control current to reduce the wheel cylinder pressure. In a vehicle braking force control device that controls a wheel cylinder pressure to a target wheel cylinder pressure by controlling a normally open solenoid valve, the normally open solenoid valve is controlled when the normally open solenoid valve is to be fully closed. An upper limit value of the wheel cylinder pressure increasing gradient is set according to the control current supplied to the open type solenoid valve, and the wheel cylinder pressure increasing gradient is limited to the upper limit value or less to limit the normally closed electromagnetic valve. This is achieved by a vehicle braking force control device (structure of claim 3) characterized by controlling the valve and the normally open type electromagnetic valve.

  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 1, the braking force control device sets the target wheel cylinder pressure based on the braking operation amount of the driver. And calculating a target control current of the normally closed solenoid valve and the normally open solenoid valve for setting the wheel cylinder pressure to the target wheel cylinder pressure, and the normally closed solenoid valve based on the target control current And the target wheel cylinder according to a control current supplied to the normally open solenoid valve when the normally open solenoid valve is to be fully closed. The pressure is reduced and corrected, and the target wheel cylinder pressure is limited to the upper limit value or less by calculating the target control current of the normally closed solenoid valve based on the corrected target wheel cylinder pressure ( Claim 2 configuration).

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 3, the braking force control device sets the target wheel cylinder pressure based on the braking operation amount of the driver. And calculating a target control current of the normally closed solenoid valve and the normally open solenoid valve for setting the wheel cylinder pressure to the target wheel cylinder pressure, and the normally closed solenoid valve based on the target control current And the normally open solenoid valve is controlled, and the normally open solenoid valve is controlled according to a control current supplied to the normally open solenoid valve when the normally open solenoid valve is to be fully closed. The pressure increase gradient of the wheel cylinder pressure is limited to the upper limit value or less by reducing and correcting the target control current of the electromagnetic valve of the type (configuration of claim 4).

  According to the present invention, in order to effectively achieve the above main problems, in the configuration of the above claims 1 to 4, the braking force control device is in a control mode for increasing or maintaining the wheel cylinder pressure. It is constituted so that it may be judged that it is a time when the normally open type solenoid valve should be in a fully closed state at a certain time (configuration of claim 5).

  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 current control device has a rated maximum current for the normally open solenoid valve. When the above control current is supplied, the normally open solenoid valve is determined to be in a fully closed state (configuration of claim 6).

  According to the configuration of the first aspect, the upper limit value of the target wheel cylinder pressure is set according to the control current supplied to the normally open solenoid valve when the normally open solenoid valve is to be fully closed. Since the normally closed solenoid valve and the normally open solenoid valve are controlled by limiting the target wheel cylinder pressure to the upper limit value or less, the normally open pressure reducing solenoid valve is completely closed for some reason. Even if the situation does not occur, the possibility that the wheel cylinder pressure cannot be controlled to the target wheel cylinder pressure can be reduced, and an excessive control current may be supplied to the pressure increasing solenoid valve. Can be reduced.

  According to the second aspect of the present invention, the braking force control device calculates the target wheel cylinder pressure based on the amount of braking operation by the driver, and is a normally closed electromagnetic for setting the wheel cylinder pressure to the target wheel cylinder pressure. The target control current of the valve and the normally open type solenoid valve is calculated, and the normally closed type solenoid valve and the normally open type solenoid valve are controlled based on the target control current, and the normally open type solenoid valve is fully closed. The target wheel cylinder pressure is reduced and corrected according to the control current supplied to the normally open solenoid valve when it should be in the state, and the target control current of the normally closed solenoid valve is corrected based on the corrected target wheel cylinder pressure Is calculated, the target wheel cylinder pressure is limited to the upper limit value or less. Therefore, when the normally open solenoid valve is to be fully closed, the control current supplied to the normally open solenoid valve is reduced. Confirmed to be below the upper limit according to It is possible to limit the target wheel cylinder pressure.

  According to the third aspect of the present invention, when the normally open solenoid valve is to be fully closed, the upper limit of the increasing gradient of the wheel cylinder pressure is determined according to the control current supplied to the normally open solenoid valve. Value is set, and the normally-closed solenoid valve and the normally-open solenoid valve are controlled by limiting the pressure gradient of the wheel cylinder pressure to the upper limit value or less. Even if the valve does not become completely closed, it is possible to reliably increase the wheel cylinder pressure with a pressure increase gradient limited to the upper limit value or less, thereby controlling the target wheel cylinder pressure. It is possible to reduce the possibility that it will not be possible, and to reduce the possibility that an excessive control current will be supplied to the pressure increasing solenoid valve.

  According to the fourth aspect of the present invention, the braking force control device calculates the target wheel cylinder pressure based on the amount of braking operation by the driver, and is a normally closed electromagnetic for setting the wheel cylinder pressure to the target wheel cylinder pressure. The target control current of the valve and the normally open type solenoid valve is calculated, and the normally closed type solenoid valve and the normally open type solenoid valve are controlled based on the target control current, and the normally open type solenoid valve is fully closed. The target control current of the normally closed solenoid valve is reduced and corrected in accordance with the control current supplied to the normally open solenoid valve when the state is to be set, so that the pressure gradient of the wheel cylinder pressure is increased to the upper limit value. Since the pressure is limited to the following, when the normally open solenoid valve is to be fully closed, the pressure increase gradient of the wheel cylinder pressure is surely below the upper limit value according to the control current supplied to the normally open solenoid valve. Can be limited.

  According to the fifth aspect of the present invention, it is determined that the normally open solenoid valve should be fully closed when in the control mode for increasing or maintaining the wheel cylinder pressure. According to the configuration of 6, the normally open solenoid valve is determined to be in the fully closed state when the control current exceeding the rated maximum current is supplied to the normally open solenoid valve. It is possible to reliably determine when the normally open solenoid valve should be fully closed.

[Preferred embodiment of problem solving means]
According to one preferable aspect of the present invention, in the configuration of the first to sixth aspects, the braking force control device reduces the wheel cylinder pressure and the normally closed solenoid valve that increases the wheel cylinder pressure to the left and right front wheels. And a normally open solenoid valve that increases the wheel cylinder pressure on the left and right rear wheels, and a normally open solenoid valve that reduces the wheel cylinder pressure. ).

  According to another preferred embodiment of the present invention, the normally closed solenoid valve and the normally open solenoid valve are configured as linear solenoid valves in the configurations of claims 1 to 6 (preferably). Aspect 2).

  According to another preferred aspect of the present invention, in the configuration of claim 1, the braking force control device calculates the target deceleration of the vehicle based on the amount of braking operation by the driver, and the target reduction of the vehicle. It is configured to calculate the target wheel cylinder pressure of each wheel based on the speed, and when calculating the target wheel cylinder pressure based on the target deceleration of the vehicle, when the normally open solenoid valve should be fully closed The target wheel cylinder pressure is reduced and corrected according to the control current supplied to the normally open solenoid valve (preferred aspect 3).

  According to another preferred aspect of the present invention, in the configuration of claim 3, the braking force control device calculates the target wheel cylinder pressure of each wheel based on the amount of braking operation by the driver, and the target wheel Based on the deviation between the cylinder pressure and the actual wheel cylinder pressure, it is configured to calculate the target control current of the normally closed solenoid valve and the normally open solenoid valve, and the normally open solenoid valve is fully closed. The target control current of the normally open solenoid valve is configured to be reduced and corrected in accordance with the control current supplied to the normally open solenoid valve when it should be (preferred aspect 4).

  According to another preferred aspect of the present invention, in the configuration of claim 1 or 2, the target wheel cylinder pressure is limited to an upper limit value or less when the control mode is the pressure increasing mode. (Preferred embodiment 5).

  According to another preferred aspect of the present invention, in the configuration of claim 3 or 4, when the control mode is the pressure increasing mode, the pressure gradient of the wheel cylinder pressure is limited to an upper limit value or less. Constructed (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 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 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 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 (linear solenoid valves) 50FL, 50FR, 50RL, 50RR are provided in the middle of the hydraulic control conduits 42, 44, 46, 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, 50RR function as pressure-increasing valves (holding valves) for the wheel cylinders 22FL, 22FR, 22RL, 22RR, respectively. The linear valves 60FL, 60FR, 60RL, 60RR are wheel cylinders 22FL, 22FR, 22RL, respectively. 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 the 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 flowchart shown in FIG. 2 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 based on the deviation ΔPi between the target wheel cylinder pressure Pti and the wheel cylinder pressure Pi, the linear valves 50FL-50RR and linear valves 60FL-60RR of each wheel are calculated. Target currents Ihi and Idi are calculated, and the wheel cylinder pressure Pi of each wheel becomes the target wheel cylinder pressure P The linear valves 50FL to 50RR and the linear valves 60FL to 60RR are controlled based on the target currents Ihi and Idi so as to be ti.

  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 is configured to control the linear valves 50FL to 50RR and the linear valves 60FL to 60RR so that the wheel cylinder pressure becomes the corresponding target wheel cylinder pressure.

  In the illustrated embodiment, when the control mode is the pressure increasing mode or the holding mode for the left and right rear wheels, in other words, when the linear valves 60RL and 60RR are to be fully closed, If the target control current Idj (j = rl, rr) of the linear valves 60RL, 60RR is equal to or greater than the command value for closing the linear valves 60RL, 60RR, that is, greater than the rated maximum current of the linear valve, the target of the wheel The wheel cylinder pressure Ptj (j = rl, rr) is reduced and corrected so that the wheel cylinder pressure Pj of the wheel cannot be controlled to the target wheel cylinder pressure Ptj and excessive control current is applied to the linear valves 50RL and 50RR of the wheel. Is prevented from being supplied.

  Next, the braking force control in the 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. Steps 80 and 90 are executed only for the left and right rear wheels.

  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 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 30, 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 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. 3 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. 5 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 a coefficient of the target wheel cylinder pressure of each wheel with respect to the final target deceleration Gt (a positive conversion 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 80, it is determined whether or not the control mode is the pressure increasing mode for the left and right rear wheels. If a negative determination is made, the process proceeds directly to step 100. If an affirmative determination is made, step 90 is performed. In this case, the correction value Ptaj of the target wheel cylinder pressure for the left and right rear wheels is calculated according to the following equation 3 using the correction number Kaj (j = rl, rr) calculated according to the routine shown in FIG. Is calculated, and these correction values are used as the corrected target wheel cylinder pressure Ptj.
Ptaj = Kai ・ Ptj ...... (3)

  In step 100, based on the deviation ΔPi between the target wheel cylinder pressure Pti and the wheel cylinder pressure Pi of each wheel, the target current Ihi of the linear valves 50FL to 50RR and the function corresponding to the graph shown in FIG. The target current Idi of the linear valves 60FL to 60RR is calculated. In step 130, the linear valves 50FL to 50RR and the linear valves 60FL to 60RR are controlled based on the target currents Ihi and Idi. Is controlled to be the target wheel cylinder pressure Pti.

  FIG. 3 is a flowchart showing a correction coefficient Kaj calculation routine for the target wheel cylinder pressure Ptj of the left and right rear wheels in the first embodiment. The calculation of the correction coefficient Kaj by the routine shown in FIG. 3 is executed by interruption every predetermined time for the left and right rear wheels in the order of the left rear wheel and the right rear wheel, for example.

  First, in step 210, it is determined whether or not the braking force control mode of the wheel is the pressure increasing mode or the holding mode. If a negative determination is made, the process proceeds to step 260, where an affirmative determination is made. Sometimes go to step 220.

  In step 220, whether or not the command value for the pressure reducing valve (linear valve 60RL, 60RR) of the wheel, that is, the target control current Idj (j = rl, rr) is equal to or greater than the current value for closing the pressure reducing valve. In other words, it is determined whether or not the control state is such that the valve is closed if the pressure reducing valve of the wheel is normal. If an affirmative determination is made, in step 230, the target control current Idj is determined. The correction coefficient Kaj is calculated from the map corresponding to the graph shown in FIG. 7, and the correction coefficient Kaj is maintained at the previous value in step 240.

  Thus, according to the illustrated first embodiment, the target wheel cylinder pressure Pti of each wheel is calculated based on the amount of braking operation of the driver in steps 40 to 70, and when the linear valves 60RL and 60RR are normal, the correction coefficient Kai is set to 1, and the target wheel cylinder pressure Ptj for the left and right rear wheels is not reduced and corrected so that the wheel cylinder pressure Pi of each wheel becomes the target braking pressure Pti higher than the master cylinder pressures Pm1 and Pm2. The on-off valves 24L and 24R are controlled in a brake-by-wire manner with the valves closed.

  On the other hand, if an abnormality occurs in which the linear valve 60RL or 60RR is not completely closed, an affirmative determination is made in steps 210 and 220, and the correction coefficient Kai is set to a value smaller than 1 in step 230. Since the target wheel cylinder pressure Ptj for the left and right rear wheels is reduced and corrected, it becomes impossible to control the wheel cylinder pressure Pj of the wheel to the target wheel cylinder pressure Ptj and excessive control current is applied to the linear valves 50RL and 50RR of the wheel. Can be reliably prevented from being supplied.

  In particular, according to the illustrated first embodiment, when the target control current Idj of the linear valves 60RL and 60RR is equal to or greater than the command value for closing the linear valves 60RL and 60RR, the correction coefficient Kai is higher than the target control current Idj. Since it is set in accordance with the target control current Idj so as to become smaller, the target wheel cylinder pressure Ptj of the left and right rear wheels can be appropriately reduced and corrected according to the extent to which the linear valves 60RL and 60RR cannot be closed.

  Further, according to the illustrated embodiment 1, when it is determined in step 80 that the control mode is the pressure increasing mode for the left and right rear wheels, the correction value Ptaj of the target wheel cylinder pressure for the left and right rear wheels is calculated, Since these correction values are the corrected target wheel cylinder pressure Ptj, the target wheel cylinder pressure Ptj for the left and right rear wheels is corrected to be unnecessarily reduced when the control mode is the holding mode or the pressure increasing mode. It can be surely prevented.

  FIG. 9 is a flowchart showing a braking force control routine in the second embodiment of the vehicle braking force control apparatus according to the present invention, and FIG. 10 is a flowchart showing a correction coefficient Kbj calculation routine in the second embodiment. In FIG. 9 and FIG. 10, the same steps as those shown in FIG. 2 and FIG. 3 are assigned the same step numbers as those shown in FIG. 2 and FIG. The calculation of the correction coefficient Kbj by the routine shown in FIG. 10 is also executed by interruption every predetermined time for the left and right rear wheels in the order of the left rear wheel and the right rear wheel, for example. Steps 100 and 110 are executed only for the left and right rear wheels.

In this embodiment, steps 10 to 70, 100, and 130 are executed in the same manner as in the above-described embodiment 1. However, in step 110 executed after step 100, the steps of embodiment 1 are executed. As in the case of 80, it is determined whether or not the control mode is the pressure increasing mode for the left and right rear wheels. If a negative determination is made, the process proceeds to step 130, and if an affirmative determination is made, the process proceeds to step 120. Then, the target control current correction value Ihbj for the rear wheel linear valves 50RL and 50RR is calculated according to the following equation 4, and the target control current correction value Ihbj is set as the corrected target control current Ihj. The target control current Ihj is reduced and corrected.
Ihbj = Kbi ・ Ihj (4)

  Steps 210 and 220 shown in FIG. 10 are executed in the same manner as in the first embodiment described above. When an affirmative determination is made in step 220, step 250 is executed based on the target control current Idj. When the correction coefficient Kbj is calculated from the map corresponding to the graph shown in FIG. 5 and a negative determination is made in step 210 or 220, the correction coefficient Kbj is maintained at the previous value in step 260.

  Therefore, according to the second embodiment shown in the figure, when an abnormality occurs in which the linear valve 60RL or 60RR is not completely closed, an affirmative determination is made in steps 210 and 220, and the correction coefficient Kbi is determined in step 250. Since the target control current Ihj for the pressure increasing linear valve for the left and right rear wheels is reduced and corrected, the wheel cylinder pressure Pj of the wheel cannot be increased to the target wheel cylinder pressure Ptj. It is possible to reliably prevent an excessive control current from being supplied to the linear valves 50RL and 50RR of the wheel.

  In particular, according to the illustrated embodiment 2, when the target control current Idj of the linear valves 60RL and 60RR is equal to or greater than the command value for closing the linear valves 60RL and 60RR, the correction coefficient Kbi is high in the target control current Idj. Since it is set according to the target control current Idj so as to become smaller, the target control current Ihj for the pressure increasing linear valve for the left and right rear wheels is appropriately reduced and corrected according to the extent to which the linear valves 60RL and 60RR cannot be closed. be able to.

  Further, according to the illustrated embodiment 2, the target control current Idj is reduced and corrected when it is determined in step 100 that the control mode is the pressure increasing mode for the left and right rear wheels. Alternatively, it is possible to reliably prevent the target control current Ihj for the pressure increasing linear valves for the left and right rear wheels from being unnecessarily reduced and corrected when in the pressure increasing mode.

  According to the first and second embodiments shown in the drawings, since the linear valves 60RL and 60RR for the left and right rear wheels are normally open solenoid valves, an abnormality occurs in which the linear valve 60RL or 60RR is not completely closed. Even when the braking force of the driver is increased in a situation where the braking force of the vehicle is limited, and the braking force of the front wheel is thereby increased, the lateral force of the rear wheel is reduced due to the braking force of the rear wheel. Therefore, compared with the case where the linear valves 60FL, 60FR on the left and right front wheels are normally open solenoid valves, in other words, an abnormality occurs in these, and the braking force on the rear wheels is increased. It is possible to reliably reduce the possibility of deterioration in vehicle behavior due to a decrease in lateral force of the rear wheels.

  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 first embodiment described above, when an abnormality occurs in which the linear valve 60RL or 60RR is not completely closed, the target wheel cylinder pressure Ptj itself for the left and right rear wheels is reduced and corrected. For example, the target wheel cylinder pressure Ptj of the left and right rear wheels may be corrected so as to be calculated as a reduced value by multiplying the right side of Equation 1 by the correction coefficient Kai.

  In the second embodiment described above, when an abnormality occurs in which the linear valve 60RL or 60RR is not completely closed, the target control current Ihj itself for the linear valves 50RL and 50RR is reduced and corrected. However, the deviation ΔPi between the target wheel cylinder pressure of the left and right rear wheels and the wheel cylinder pressure may be corrected so as to reduce and correct the target control current Ihj for the linear valves 50RL and 50RR.

  In each of the above-described embodiments, if an abnormality occurs in which the linear valve 60RL or 60RR is not completely closed, the target wheel cylinder pressure Ptj for the left and right rear wheels is individually reduced and corrected for the left and right rear wheels, or The deviation ΔPi between the target wheel cylinder pressure and the wheel cylinder pressure is corrected to be reduced. However, any rear yaw moment is not applied to the vehicle due to the braking force difference between the left and right rear wheels. When an abnormality occurs in which the linear valve 60RL or 60RR of the wheel does not completely close, the target wheel cylinder pressure Ptj is corrected to be reduced for both the left and right rear wheels, or the deviation ΔPi between the target wheel cylinder pressure and the wheel cylinder pressure is corrected. May be corrected so as to be reduced.

  In each of the above-described embodiments, the target control currents Ihi and Idi of each wheel are calculated from the map shown in FIG. 8, but the map is variably set according to the target control current Idj. The target wheel cylinder Pti and the target control currents Ihi and Idj of each wheel may be calculated by a function, and these functions may be corrected to be variably set according to the target control current Idj. Good.

  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 the driver's required deceleration Gt, the target wheel cylinder 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.

  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 a first embodiment of a vehicle braking force control apparatus according to the present invention and a block diagram showing a control system; Example 1 3 is a flowchart showing a braking force control routine in the first embodiment. Example 1 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) 7 is a flowchart showing a correction coefficient Kaj calculation routine for a target wheel cylinder pressure Ptj of left and right rear wheels in the first embodiment. Example 1 It is a graph which shows the relationship between the target control current Idj of linear valves 60RL and 60RR, and the correction coefficient Kaj. Example 1 It is a graph which shows the relationship between wheel cylinder pressure (DELTA) Pi and target control current Ihi and Idj. (Examples 1 and 2) 7 is a flowchart showing a braking force control routine in Embodiment 2. (Example 2) 10 is a flowchart showing a correction coefficient Kbi calculation routine for a target control current Ihj for left and right rear wheels in the second embodiment. (Example 2) It is a graph which shows the relationship between the target control current Idj of the linear valves 60RL and 60RR and the correction coefficient Kbj. (Example 2)

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)

  A normally closed solenoid valve that operates according to the supplied control current to increase the wheel cylinder pressure, and a normally open solenoid valve that operates according to the supplied control current to reduce the wheel cylinder pressure; In a vehicle braking force control device for controlling a wheel cylinder pressure to a target wheel cylinder pressure by controlling the normally closed solenoid valve and the normally open solenoid valve, the normally open solenoid valve is fully The upper limit value of the target wheel cylinder pressure is set according to the control current supplied to the normally open solenoid valve when the valve is to be closed, and the target wheel cylinder pressure is limited to the upper limit value or less to limit the normally closed state. A braking force control apparatus for a vehicle, which controls a solenoid valve of a mold and the normally open solenoid valve.   The braking force control device calculates a target wheel cylinder pressure based on a braking operation amount of a driver, and the normally closed solenoid valve and the normally open solenoid valve for setting the wheel cylinder pressure to the target wheel cylinder pressure. When the normally open solenoid valve is to be fully closed, the normally closed solenoid valve and the normally open solenoid valve are controlled based on the target control current. The target wheel cylinder pressure is reduced and corrected according to the control current supplied to the normally open solenoid valve, and the target control current of the normally closed solenoid valve is calculated based on the corrected target wheel cylinder pressure. The vehicle braking force control device according to claim 1, wherein the target wheel cylinder pressure is limited to be equal to or less than the upper limit value.   A normally closed solenoid valve that operates according to the supplied control current to increase the wheel cylinder pressure, and a normally open solenoid valve that operates according to the supplied control current to reduce the wheel cylinder pressure; In a vehicle braking force control device for controlling a wheel cylinder pressure to a target wheel cylinder pressure by controlling the normally closed solenoid valve and the normally open solenoid valve, the normally open solenoid valve is fully The upper limit value of the pressure increase gradient of the wheel cylinder pressure is set according to the control current supplied to the normally open solenoid valve when it should be closed, and the pressure increase gradient of the wheel cylinder pressure is set to be equal to or lower than the upper limit value. A vehicle braking force control device that controls the normally closed solenoid valve and the normally open solenoid valve in a limited manner.   The braking force control device calculates a target wheel cylinder pressure based on a braking operation amount of a driver, and the normally closed solenoid valve and the normally open solenoid valve for setting the wheel cylinder pressure to the target wheel cylinder pressure. When the normally open solenoid valve is to be fully closed, the normally closed solenoid valve and the normally open solenoid valve are controlled based on the target control current. The pressure increase gradient of the wheel cylinder pressure is limited to the upper limit value or less by correcting the target control current of the normally closed solenoid valve to be reduced according to the control current supplied to the normally open solenoid valve. The vehicle braking force control device according to claim 3.   2. The braking force control device according to claim 1, wherein when the control unit is in a control mode for increasing or maintaining a wheel cylinder pressure, it is determined that the normally open solenoid valve should be fully closed. 4. A braking force control device for a vehicle according to 4. The braking force control device determines that the normally open solenoid valve is to be fully closed when a control current greater than a rated maximum current is supplied to the normally open solenoid valve. The braking force control device for a vehicle according to any one of claims 1 to 4.

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