JP2012254651A - Hydraulic brake system, and hydraulic brake control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a braking distance from being extended even on the occurrence of abnormal conditions in at least one of a hydraulic system and an electric system, in front-rear piping of two systems.SOLUTION: When both of a hydraulic system and an electric system are normal, first and second electromagnetic valves 14, 15 are opened, and third and fourth electromagnetic valves 18, 19 are closed to establish front-rear piping. A brake fluid is supplied/discharged to left and right front brake cylinders 8, 9 in a first system, and is supplied/discharged to left and right rear brake cylinders 10, 11 in a second system. During abnormal conditions of the hydraulic system or the electric system, on-off valves 14, 15 are closed and on-off valves 18, 19 are opened to establish X piping. The brake fluid is supplied/discharged to the left front brake cylinder 8 and the right rear brake cylinder 11 in the first system, and is supplied/discharged to the right front brake cylinder 9 and the left rear brake cylinder 10 in the second system.

Description

  The present invention relates to a technical field of a hydraulic brake system that uses hydraulic pressure and employs two systems of front and rear pipes, and a technical field of a hydraulic brake control method.

  2. Description of the Related Art Conventionally, in a brake system for a vehicle such as an automobile, a hydraulic brake system that uses hydraulic pressure, employs first and second brake pipes, and operates the hydraulic brake in cooperation with a regenerative brake has been proposed. (For example, refer to Patent Document 1).

  In the hydraulic brake system described in Patent Document 1, the target braking force to be applied to the vehicle according to the brake operation state when the brake is operated by depressing the brake pedal, the hydraulic braking force by the hydraulic brake and the regenerative braking by the regenerative brake are used. It is gained by power. In that case, the brake hydraulic pressure is controlled by a hydraulic control unit (H / U) disposed in two brake pipes of the hydraulic brake system.

  By the way, in the hydraulic brake system described in Patent Document 1, the brake pipes of the first and second systems are set to the front and rear pipes during normal braking in the normal state of the brake system. In the front and rear piping, the left and right front wheel brake cylinders are operated with the brake fluid pressure of the first system, and the left and right rear wheel brake cylinders are operated with the brake fluid pressure of the second system. According to this front and rear piping, since the braking force is applied equally to the left and right wheels when the brake is operated, yaw is not generated in the vehicle, and the vehicle can be stopped in a stable posture.

  On the other hand, a hydraulic brake system in which two brake pipes are set as X pipes has also been proposed (see, for example, Patent Document 2). The hydraulic brake system described in Patent Document 2 is also a hydraulic brake system that operates the hydraulic brake in cooperation with the regenerative brake. In X piping, the left front wheel brake cylinder and the right rear wheel brake cylinder are operated by the brake fluid pressure of the first system, and the right front wheel brake cylinder and the left rear wheel brake cylinder are operated by the brake fluid pressure of the second system. Is done. With this X piping, there is a possibility that yaw is slightly generated in the vehicle when the brake is operated. However, since the differential pressure between the two systems is practically small, the generation of yaw has almost no problem. Therefore, the vehicle can be stopped in a stable posture even by the X piping.

Japanese Unexamined Patent Publication No. 2009-161181. JP, 2011-57140, A.

  By the way, in order to stop the vehicle in a stable posture as described above, when the front and rear pipes are employed in the hydraulic brake system of the vehicle as in the hydraulic brake system described in Patent Document 1, the following problems occur. Conceivable. That is, there is a possibility that an abnormality occurs in the electric system of the hydraulic brake system, and the brake hydraulic pressure is not supplied to the brake cylinder of one system, so that the brake cylinder cannot brake the corresponding wheel. If the brake cylinder of one system cannot brake the wheel in this way, the braking force of the entire vehicle is reduced and the braking distance is extended.

  In addition, an abnormality occurs in one hydraulic system in the two hydraulic brake systems, and the brake hydraulic pressure is not supplied to one brake cylinder, and the brakes cannot be applied to the wheels corresponding to the one brake cylinder. There is a possibility. If the brake cylinder of one system can no longer brake the wheels in this way, the braking force of the entire vehicle is reduced and the braking distance is extended, as in the case of an abnormality in the electric system.

  The present invention has been made in view of such circumstances. The purpose of the present invention is to increase the braking distance even if an abnormality occurs in at least one of the hydraulic system and the electrical system in the two systems of front and rear piping. To provide a hydraulic brake system and a hydraulic brake control method that can be suppressed.

  In order to solve the above-described problems, the hydraulic brake system of the present invention includes a left and right front wheel brake cylinder that generates a braking force for the left and right front wheels, and a left and right rear wheel that generates a braking force for the left and right rear wheels, respectively. When the brake cylinder and the hydraulic system are normal and the electrical system is normal, brake fluid is supplied to and discharged from the left and right front wheel brake cylinders using the first and second system brake pipes and the first system brake pipe. And the front and rear piping for supplying and discharging brake fluid to the left and right rear wheel brake cylinders by the brake piping of the second system, and an abnormality in one of the hydraulic systems of the first and second systems The brake piping of the first system and the second system are connected to the brake system of the first system in at least one of the time and when the electric system is abnormal. The brake fluid is supplied to and discharged from either the left or right of the left and right front wheel brake cylinders and the right or left of the left and right rear wheel brake cylinders, and the left or right of the left and right front wheel brake cylinders is A pipe switching unit for setting X piping for supplying and discharging brake fluid to the left and right of the other and the left and right rear brake cylinders, and controlling the pipe switching unit to control the first and second systems. And a control unit that sets the brake pipe as the front and rear pipes or the X pipe.

  In the hydraulic brake system of the present invention, the pipe switching unit detects an abnormality in the electric system and outputs an electric system abnormality detection signal to the control unit, and the left and right front wheel brakes. Detecting a brake fluid pressure of either one of the cylinders and detecting a brake fluid pressure of either the first pressure sensor that outputs a first brake fluid pressure detection signal to the control unit or the left and right rear wheel brake cylinders; A second pressure sensor that outputs a second brake fluid pressure detection signal to the control unit, wherein the control unit detects the electrical system abnormality detection signal, the first brake fluid pressure detection signal, and the second brake fluid. The pipe switching unit is controlled based on a pressure detection signal.

Furthermore, in the hydraulic brake system of the present invention, the pipe switching unit includes a normally closed first electromagnetic control valve, a normally closed second electromagnetic control valve, a normally open third electromagnetic control valve, and a normally open fourth electromagnetic control valve. An electromagnetic control valve, and the first system brake pipe is connected to the left front wheel brake cylinder branch brake pipe for supplying and discharging the brake fluid to the left front wheel brake cylinder, and to the right front wheel brake cylinder. The left rear wheel is branched into the right front wheel brake cylinder branch brake pipe for supplying and discharging the brake fluid, and the second system brake pipe supplies and discharges the brake fluid to the left rear wheel brake cylinder. Divided into a branch brake pipe for the brake cylinder and a branch brake pipe for the right rear wheel brake cylinder that supplies and discharges the brake fluid to the right rear wheel brake cylinder. The first electromagnetic on-off valve is disposed on the branch brake pipe for the right front wheel brake cylinder, the second electromagnetic on-off valve is disposed on the branch brake pipe for the right rear wheel brake cylinder, and the first The right rear wheel on the right front wheel brake cylinder side of the right front wheel brake cylinder or the branch brake pipe for the right front wheel brake cylinder on the opposite side of the right front wheel brake cylinder side of the electromagnetic on / off valve or the first system brake pipe and the second electromagnetic on / off valve A first connection brake pipe for connecting a branch brake pipe for a wheel brake cylinder is provided, and the branch brake pipe for the right rear wheel brake cylinder on the side opposite to the right rear wheel brake cylinder side of the second electromagnetic on-off valve; A branch brake arrangement for the right front wheel brake cylinder on the right front wheel brake cylinder side of the second system brake piping and the first electromagnetic on-off valve A second connection brake pipe is connected to the first connection brake pipe, the third electromagnetic on-off valve is arranged on the second connection brake pipe, and the fourth electromagnetic on-off valve is arranged on the second connection brake pipe. The control unit opens the first and second electromagnetic on-off valves and closes the third and fourth electromagnetic on-off valves when the hydraulic system is normal and the electric system is normal; and Closing the first and second electromagnetic on-off valves and opening the third and fourth electromagnetic on-off valves in at least one of an abnormality in one of the hydraulic systems in the second system and an abnormality in the electrical system It is characterized by.

  On the other hand, the hydraulic brake control method according to the present invention controls the supply and discharge of brake fluid to the left and right front wheel brake cylinders through the brake piping of the first system and the right and left rear when the hydraulic system is normal and the electrical system is normal. Brake fluid is supplied to and discharged from the wheel brake cylinder through the second system brake pipe, and at least one of the abnormality in the hydraulic system of one of the first and second systems and the abnormality in the electrical system The brake fluid is supplied to and discharged from the left and right front brake cylinders by the first system brake piping, and the first system is applied to the left and right rear brake cylinders. The brake fluid is supplied and discharged through the brake piping and the left and right front brake cylinders The brake fluid is supplied / discharged through the second system brake piping, and the brake fluid is supplied / discharged from the left / right rear wheel brake cylinders through the second system brake piping. It is characterized by.

  According to the hydraulic brake system and the hydraulic brake control method of the present invention configured as described above, when no abnormality occurs in either the hydraulic system or the electrical system of the hydraulic brake system, The brake piping of the second system is set as the front and rear piping. Thereby, it is possible to prevent yaw from being generated in the vehicle when the brake is operated. Therefore, the vehicle can be stopped in a stable posture during normal braking operation.

  Further, when an abnormality occurs in the electrical system of the hydraulic brake system, the brake piping of the first and second systems is switched from the front and rear piping to the X piping. As a result, even if the brake fluid pressure is not supplied to one brake cylinder due to the occurrence of an abnormality in the electric system, it is possible to suppress a decrease in brake force and to obtain a sufficient deceleration even when an abnormality occurs in the electric system. It becomes possible. Further, when an abnormality occurs in one of the two hydraulic systems of the hydraulic brake system, the brake piping of the first and second systems is switched from the front and rear piping to the X piping. Thereby, even if brake fluid pressure is no longer supplied to one system of brake cylinders, it is possible to suppress a decrease in brake force and to obtain a sufficient deceleration even when an abnormality occurs in the electrical system.

  In particular, in general vehicles, heavy objects such as engines are often arranged on the front side of the vehicle, but in such a vehicle when an abnormality occurs in the brake system for the left and right front wheels in the front and rear piping. Sufficient deceleration can be obtained more effectively. In this way, it is possible to suppress an increase in the braking distance even if an abnormality occurs in at least one of the hydraulic system and the electrical system in the two systems of front and rear piping.

Further, since the first to fourth solenoid on-off valves having simple configurations are simply incorporated into the two systems of brake piping, the piping switching unit can be made compact and the work of external brake piping is not required. It is possible to reduce restrictions on mounting the switching unit on the vehicle.

It is a figure showing typically the time of non-energization to an electric system in an example of an embodiment of a hydraulic brake system concerning the present invention. It is a figure explaining the piping method of the hydraulic brake system concerning the present invention. It is a figure which shows typically the time of electricity supply to the electric system of the hydraulic brake system of the example shown in FIG. FIG. 2 is a block diagram for pipe switching control in the hydraulic brake system of the example shown in FIG. 1. It is a figure which shows the flow for implementing piping switching control.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing an example of an embodiment of a hydraulic brake system according to the present invention when no power is supplied to an electric system, and FIG. 2 is a diagram for explaining a piping method of the hydraulic brake system according to the present invention. It is.

As shown in FIG. 1, the hydraulic brake system 1 of this example is basically the same as a conventionally known two-system hydraulic brake system. That is, the hydraulic brake system 1 includes a brake pedal 2, a booster 3, a tandem master cylinder 4, a reservoir tank 5, first and second system brake pipes 6 and 7, a left front wheel brake cylinder 8, a right front wheel brake cylinder. 9, a left rear wheel brake cylinder 10 and a right rear wheel brake cylinder 11 are provided.

  The tandem master cylinder 4 is a conventionally known tandem master cylinder. A primary piston 4 a and a secondary piston 4 b are slidably disposed in the cylinder hole of the cylinder body of the tandem master cylinder 4. A primary hydraulic chamber 4c is defined by the primary piston 4a and the secondary piston 4b, and a secondary hydraulic chamber 4d is defined by the secondary piston 4b.

The secondary hydraulic chamber 4d is connected to the first system brake pipe 6. The brake pipe 6 is connected to the left and right front wheel brake cylinders 8 and 9 of the left front wheel FL and the right front wheel FR via first and second branch brake pipes 6a and 6b branched in the middle. The primary hydraulic chamber 4c is connected to the second system brake pipe 7. The brake pipe 7 is connected to the left rear wheel RL via third and fourth branch brake pipes 7a and 7b branched in the middle.
And connected to the left and right rear wheel brake cylinders 10, 11 of the right rear wheel RR.

The hydraulic brake system 1 of this example includes a hydraulic control unit (H / U) 12 disposed in the first to fourth branch brake pipes 6a, 6b, 7a, 7b. The H / U 12 has an electric system for electrically controlling the brake fluid pressure, and is a conventionally known H / U for performing antilock brake control, traction control, and the like, for example. The operation of the H / U 12 is not directly related to the hydraulic brake system of the present invention, and a detailed description thereof is omitted here. And the 1st thru | or 4th branch brake piping 6a, 6b, 7a, 7b by the side of the tandem master cylinder 4 of H / U12 and the 1st thru | or 4th branch brake by the side of the brake cylinder 8, 9, 10, 11 of H / U12 The pipes 6a, 6b, 7a, 7b are always in communication.

Further, the hydraulic brake system 1 of this example includes the second and fourth branch brake pipes 6b, 7
A pipe switching unit 13 is disposed over b. The pipe switching unit 13 includes a first electromagnetic switching valve 14, a second electromagnetic switching valve 15, a first piping switching brake pipe 16, a second piping switching brake pipe 17, a third electromagnetic switching valve 18, and a fourth electromagnetic switch. An on-off valve 19 is provided.

  The first electromagnetic open / close valve 14 is a normally closed electromagnetic open / close valve that is disposed in the second branch brake pipe 6b and is closed when not energized. The second electromagnetic open / close valve 15 is a normally closed electromagnetic open / close valve that is disposed in the fourth branch brake pipe 7b and is closed when not energized. The first pipe switching brake pipe 16 includes a second branch brake pipe 6b on the master cylinder 4 side of the first electromagnetic on-off valve 14 and a fourth branch brake pipe 7b on the right rear wheel brake cylinder 11 side of the second electromagnetic on-off valve 15. And connect. The first pipe switching brake pipe 16 may be connected to the first system brake pipe 6 before branching instead of the second branch brake pipe 6b. The second pipe switching brake pipe 17 includes a fourth branch brake pipe 7b on the master cylinder 4 side of the second electromagnetic on-off valve 15 and a second branch brake pipe 6b on the right front wheel brake cylinder 9 side of the first electromagnetic on-off valve 14. Connect. The second pipe switching brake pipe 17 can be connected to the second system brake pipe 7 before branching instead of the fourth branch brake pipe 7b.

  The third electromagnetic open / close valve 18 is a normally open electromagnetic open / close valve that is disposed in the first pipe switching brake pipe 16 and opens when not energized. The fourth electromagnetic on-off valve 19 is a normally open electromagnetic on-off valve that is disposed in the second pipe switching brake pipe 17 and that opens when no power is supplied.

In the hydraulic brake control method of this example, the pipes of the first and second system brake pipes 6 and 7 are set as follows. That is, as shown in FIG. 2, when the ignition switch is OFF, the piping is set to be X piping. Further, when the ignition switch is on and both the hydraulic system and the electrical system are normal, the piping is set to be front and rear piping. Further, when the ignition switch is on, the electrical system is normal, and the hydraulic system is abnormal, the piping is set to be X piping. Furthermore, the piping is set to be X piping even when the ignition switch is on, the hydraulic system is normal, and the electrical system is abnormal. Further, when the ignition switch is on and both the hydraulic system and the electrical system are abnormal, the piping is set to be X piping.

And in X piping, the 1st thru | or 4th electromagnetic on-off valve 14,15,18,19 is not energized. Accordingly, as shown in FIG. 1, the first and second electromagnetic on-off valves 14 and 15 are closed, and the third and fourth electromagnetic on-off valves 18 and 19 are opened. Accordingly, the secondary hydraulic chamber 4d and the left front wheel brake cylinder 8 are connected by the brake pipes 6 and 6a shown by the solid line in FIG. 1, and the secondary hydraulic chamber 4d and the right rear wheel brake cylinder 11 are shown in FIG. They are connected by brake pipes 6, 6b, 16, 7b indicated by solid lines. Further, the primary hydraulic chamber 4c and the left rear wheel brake cylinder 10 are connected by brake pipes 7 and 7a indicated by dotted lines in FIG. 1, and the primary hydraulic chamber 4c and the right front wheel brake cylinder 9 are dotted lines in FIG. Are connected by brake pipes 7, 7b, 17, 6b.

On the other hand, in the front and rear piping, all of the first to fourth electromagnetic on-off valves 14, 15, 18, and 19 are energized. Therefore, as shown in FIG. 3, the first and second electromagnetic on-off valves 14 and 15 are switched and opened, and the third and fourth electromagnetic on-off valves 18 and 19 are switched and closed. Thereby, the secondary hydraulic chamber 4d and the left front wheel brake cylinder 8 are connected by the brake pipes 6 and 6a shown by the solid line in FIG. 1, and the secondary hydraulic chamber 4d and the right front wheel brake cylinder 9 are shown by the solid line in FIG. Are connected by brake pipes 6 and 6b. Further, the primary hydraulic chamber 4c and the left rear wheel brake cylinder 10 are connected to brake pipes 7, 7a indicated by dotted lines in FIG.
And the primary hydraulic chamber 4c and the right rear wheel brake cylinder 11 are connected by brake pipes 7 and 7b indicated by dotted lines in FIG. As shown in FIG. 4, the first to fourth electromagnetic on-off valves 14, 15, 18, 19 are all connected to an electronic control unit (ECU) 20.

Further, as shown in FIGS. 1, 3, and 4, the pipe switching unit 13 includes an electrical system abnormality detection signal output unit 21, first and second pressure sensors 22 and 23, and a stroke sensor 24.
Have The electrical system abnormality detection signal output unit 21 has a self-diagnosis circuit that diagnoses the electrical system of the hydraulic brake system 1. The electrical system abnormality detection signal output unit 21 is connected to the ECU 20. When the self-diagnosis circuit of the electric system abnormality detection signal output unit 21 detects an abnormality in the electric system of the hydraulic brake system 1, an electric system abnormality detection signal is output to the ECU 20. As this self-diagnosis circuit, for example, a self-diagnosis circuit for diagnosing an electric system of a conventional hydraulic brake system can be used. The first pressure sensor 22 detects the brake fluid pressure of the first system (specifically, the brake fluid pressure of the right front wheel brake cylinder 9), and outputs the brake fluid pressure detection signal to the ECU 20. Further, the second pressure sensor 23 detects the brake fluid pressure of the second system (specifically, the brake fluid pressure of the right rear wheel brake cylinder 11) and outputs the brake fluid pressure detection signal to the ECU 20. Further, the stroke sensor 24 detects the depression stroke of the brake pedal 2 and outputs it to the ECU 20.

Further, an ignition switch 25 is connected to the ECU 20, and the ignition switch 25 outputs a switch on / off signal to the ECU 20. The ECU 20 detects an electrical system abnormality detection signal from the electrical system abnormality detection signal output unit 21, each brake fluid pressure detection signal from the first and first pressure sensors 22 and 23, and a stroke detection signal from the stroke sensor 24. Further, the switching of the piping in the hydraulic brake system 1 is controlled by controlling the opening and closing of the first to fourth electromagnetic on-off valves 14, 15, 18, 19 based on the switch on / off signal from the ignition switch 25.

Next, the pipe switching control in the hydraulic brake system 1 and the hydraulic brake control method of this example will be described. FIG. 5 is a diagram illustrating a flow for performing pipe switching control.
As shown in FIG. 5, when the ignition switch 27 is off in step S <b> 1, the ECU 20 does not energize the first to fourth electromagnetic on-off valves 14, 15, 18, 19. As a result, the first and second electromagnetic on-off valves 14 and 15 are closed, and the third and fourth electromagnetic on-off valves 18 and 19 are opened. Therefore, the piping of the hydraulic brake system 1 is set to the X piping shown in FIG. Next, it is determined in step S2 whether or not the ignition switch 27 is turned on. If it is determined that the ignition switch 27 is not turned on, that is, the ignition switch 27 is turned off, the pipe switching control ends. At this time, the piping of the hydraulic brake system 1 is held by the X piping.

  If it is determined in step S2 that the ignition switch 27 is turned on, it is determined in step S3 whether or not there is an abnormality in the electrical system of the hydraulic brake system 1. If it is determined that there is no abnormality in the electric system, in step S4, the ECU 20 determines that the electric system of the hydraulic brake system 1 is normal, and as shown in FIG. 15 is opened, and the third and fourth electromagnetic on-off valves 18 and 19 are closed. Thereby, piping is set to front and rear piping.

Next, it is determined whether or not the brake pedal 2 is depressed in step S5. If it is determined that the brake pedal 2 is not depressed, the process of step S5 is repeated. If it is determined that the brake pedal 2 is depressed, it is determined in step S6 whether or not there is an abnormality in the hydraulic system. That is, when the brake pedal 2 is depressed, the brake fluid pressures of the first and second systems correspond to the depression stroke of the brake pedal 2 based on the brake fluid pressure detection signals from the first and second pressure sensors 22 and 23, respectively. When it is detected that the hydraulic pressure has risen and it is determined that there is no abnormality in the hydraulic system, the normal brake operation by the front and rear piping is performed in step S7.

That is, when both the hydraulic system and the electrical system are normal, the brake pedal 2 is depressed, and the brake is applied to the primary hydraulic chamber 4c and the secondary hydraulic chamber 4d of the tandem master cylinder 4 in the same manner as a conventionally known tandem master cylinder. Hydraulic pressure is generated. The brake hydraulic pressure generated in the secondary hydraulic pressure chamber 4d is supplied to the left front wheel brake cylinder 8 through the first system brake pipe 6 and the first branch brake pipe 6a, and the first system brake pipe 6 and the second branch brake. It is supplied to the right rear wheel brake cylinder 9 through the first electromagnetic on-off valve 14 by the pipe 6b. The left and right front wheel brake cylinders 8 and 9
Apply brakes to L and FR. Similarly, the brake fluid pressure generated in the primary fluid pressure chamber 4c is supplied to the left rear wheel brake cylinder 10 by the second system brake pipe 7 and the third branch brake pipe 7a, and the second system brake pipe 7 And, it is supplied to the right rear wheel brake cylinder 11 through the second electromagnetic opening / closing valve 15 by the fourth branch brake pipe 7b. The left and right rear wheel brake cylinders 10 and 11 brake the left and right front wheels RL and RR, respectively.

When the brake pedal 2 is released, the tandem master cylinder 4 is deactivated as in the conventional tandem master cylinder. Therefore, the brake fluid supplied to the left and right front wheel brake cylinders 8 and 9 is discharged toward the secondary hydraulic chamber 4d of the tandem master cylinder 4, and the brake fluid supplied to the left and right rear wheel brake cylinders 10 and 11 is tandem. It is discharged toward the primary hydraulic chamber 4c of the master cylinder 4.

Thus, in the hydraulic brake system 1 of this example, the brake operation is performed by the front and rear pipes during normal braking when the hydraulic system and the electric system are normal, and the brake fluid supplied by the brake pipe 6 of the first system is used. The left and right front wheels FL and FR are braked, and the left and right rear wheels RL and RR are braked by the brake fluid supplied from the second system brake pipe 7.

Even when the brake pedal 2 is depressed in step S6, it is detected that the brake fluid pressure of one of the first and second systems does not increase to the fluid pressure corresponding to the depression stroke of the brake pedal 2. If it is determined that there is an abnormality in the hydraulic system, the ECU 20 closes the first and second electromagnetic on-off valves 14 and 15 and opens the third and fourth electromagnetic on-off valves 18 and 19 in step S8. Therefore, the piping of the hydraulic brake system 1 is set to the X piping shown in FIG. In step S9, the normal brake operation using the X pipe is performed in the same manner as the normal brake operation using the front and rear pipes described above. In this case, it is assumed that the hydraulic system in which an abnormality has occurred is the first system. At this time, the left front wheel FL cylinder and the right rear wheel brake cylinder 11 are respectively operated by the hydraulic pressure at the normal position of the first system (position on the tandem master cylinder 4 side from the first electromagnetic on-off valve 14). The brake is applied to the rear wheel RR. The same applies when the hydraulic system in which an abnormality has occurred is the second system.

  Thus, in the hydraulic brake system 1 of this example, during normal braking when the electrical system is normal and the hydraulic system is abnormal, the left and right front wheels and the left and right rear wheels are braked by X piping during normal braking. Is applied.

Further, if it is determined in step S3 that there is an abnormality in the electrical system of the hydraulic brake system 1, it is determined in step S10 whether or not the brake pedal 2 has been depressed. If it is determined that the brake pedal 2 is not depressed, the process of step S10 is repeated. At this time, the hydraulic brake system 1 is held by the X pipe. If it is determined that the brake pedal 2 has been depressed, the routine proceeds to step S9 where the normal brake operation by the X pipe is performed. At this time, if there is no abnormality in the hydraulic system, the left front wheel FL and the right rear wheel RR are braked with the hydraulic pressure of the first system, and the right front wheel FL and the left rear wheel RL are braked with the hydraulic pressure of the second system. Is applied. In addition, if there is an abnormality in one of the first and second hydraulic systems, each of the normal brake operations similar to the normal brake operation by the X pipe in the case where there is an abnormality in the hydraulic system in step S6 described above. One of the wheels is braked.

  Thus, in the hydraulic brake system 1 of this example, during normal braking when the hydraulic system is normal and the electrical system is abnormal, the left and right front and rear wheels are braked by the X pipe. Further, during normal braking when one of the hydraulic systems and the electrical system are both abnormal, the left and right front wheels and the left and right rear wheels are braked by X piping.

  According to the hydraulic brake system 1 and the hydraulic brake control method of this example, when no abnormality has occurred in either the hydraulic system or the electrical system of the hydraulic brake system 1, the first switch is turned on when the ignition switch 25 is turned on. The brake pipes of the first and second systems are set as the front and rear pipes. Thereby, it is possible to prevent yaw from being generated in the vehicle when the brake is operated. Therefore, the vehicle can be stopped in a stable posture during normal braking.

  When an abnormality occurs in the electrical system of the hydraulic brake system 1, the brake piping of the first and second systems is switched from the front and rear piping to the X piping. As a result, even if the brake fluid pressure is not supplied to one brake cylinder due to the occurrence of an abnormality in the electric system, it is possible to suppress a decrease in brake force and to obtain a sufficient deceleration even when an abnormality occurs in the electric system. It becomes possible. Further, when an abnormality occurs in one of the two hydraulic systems of the hydraulic brake system 1, the brake piping of the first and second systems is switched from the front and rear piping to the X piping. Thereby, even if brake fluid pressure is no longer supplied to one system of brake cylinders, it is possible to suppress a decrease in brake force and to obtain a sufficient deceleration even when an abnormality occurs in the electrical system.

  In particular, in general vehicles, heavy objects such as engines are often arranged on the front side of the vehicle, but in such a vehicle when an abnormality occurs in the brake system for the left and right front wheels in the front and rear piping. In particular, a sufficient deceleration can be obtained more effectively. In this way, it is possible to suppress an increase in the braking distance even if an abnormality occurs in at least one of the hydraulic system and the electrical system in the two systems of front and rear piping.

In addition, since the first to fourth electromagnetic on-off valves 14, 15, 18, and 19 having simple configurations are simply incorporated into the two brake pipes, the pipe switching unit 13 can be made compact and an external brake can be provided. The labor of piping becomes unnecessary, and the mounting limitation of the piping switching unit 13 on the vehicle can be reduced.

  In addition, this invention is not limited to the above-mentioned example. For example, in the above-described example, H / U 12 is H / U for brake hydraulic pressure control such as antilock brake control and traction control, but the present invention provides H / U for regenerative cooperative hydraulic brake control. Or H / U for hydraulic pressure control of an automatic brake. In short, the present invention can be modified in various ways within the scope of the matters described in the claims.

  The hydraulic brake system and hydraulic brake control method of the present invention can be suitably used for a hydraulic brake system and a hydraulic brake control method that use hydraulic pressure and employ two systems of front and rear piping.

DESCRIPTION OF SYMBOLS 1 ... Hydraulic brake system, 2 ... Brake pedal, 4 ... Tandem master cylinder, 6 ... Brake piping of 1st system, 7 ... Brake piping of 2nd system, 8 ... Left front wheel brake cylinder, 9 ... Right front wheel brake cylinder, DESCRIPTION OF SYMBOLS 10 ... Left rear wheel brake cylinder, 11 ... Right rear wheel brake cylinder, 12 ... Fluid pressure control unit (H / U), 13 ... Pipe switching unit, 14 ... 1st electromagnetic on-off valve, 15 ... 2nd electromagnetic on-off valve, DESCRIPTION OF SYMBOLS 16 ... Brake piping for 1st piping switching, 17 ... Brake piping for 2nd piping switching, 18 ... 3rd electromagnetic switching valve, 19 ... 4th electromagnetic switching valve, 20 ... Electronic control unit (ECU), 21 ... Electric system abnormality Detection signal output unit, 22 ... first pressure sensor, 23 ... second pressure sensor, 24 ... stroke sensor, 25 ... ignition switch

Claims (4)

Left and right front wheel brake cylinders that generate braking force for the left and right front wheels respectively;
Left and right rear wheel brake cylinders that generate braking force for the left and right rear wheels respectively;
When the hydraulic system is normal and the electrical system is normal, the brake piping of the first and second systems is supplied to and discharged from the left and right front wheel brake cylinders by the brake piping of the first system, and the first The front and rear pipes for supplying and discharging brake fluid to the left and right rear wheel brake cylinders by two brake pipes are set, and when one of the first and second hydraulic systems is abnormal and the electrical system At least one of the first and second system brake pipes, the left and right front wheel brake cylinders and the left and right rear wheel brake cylinders either left and right by the first system brake pipes The brake fluid is supplied to and discharged from the brake system, and the left and right front wheel brake series are A pipe switching unit to set the X piping for supplying and discharging the brake fluid for one left or right da of the left and right other one and the left and right rear wheel brake cylinder,
A controller that controls the pipe switching unit to set the brake pipes of the first and second systems as the front and rear pipes or the X pipe;
A hydraulic brake system comprising at least The pipe switching unit detects the brake fluid pressure of either the electric system abnormality detection signal output unit that detects an abnormality of the electric system and outputs an electric system abnormality detection signal to the control unit, or the left and right front wheel brake cylinders. The first brake sensor that outputs the first brake fluid pressure detection signal to the control unit and the brake fluid pressure of either the left or right rear wheel brake cylinder are detected to control the second brake fluid pressure detection signal. A second pressure sensor that outputs to the unit,
The said control part controls the said piping switching unit based on the said electric system abnormality detection signal, the said 1st brake fluid pressure detection signal, and the said 2nd brake fluid pressure detection signal. Hydraulic brake system. The pipe switching unit has a normally closed first electromagnetic control valve, a normally closed second electromagnetic control valve, a normally open third electromagnetic control valve, and a normally open fourth electromagnetic control valve,
The first system brake piping supplies and discharges the brake fluid to the left front wheel brake cylinder, and supplies and discharges the brake fluid to the left front wheel brake cylinder and the right front wheel brake cylinder. Branch to the branch brake pipe for the right front wheel brake cylinder
The second system brake piping includes a branch brake piping for a left rear wheel brake cylinder for supplying and discharging the brake fluid to the left rear wheel brake cylinder, and the brake fluid for the right rear wheel brake cylinder. Branched to the branch brake piping for the right rear wheel brake cylinder to be supplied / discharged,
The first electromagnetic on-off valve is disposed in the branch brake pipe for the right front wheel brake cylinder,
The second electromagnetic on-off valve is disposed in the branch brake pipe for the right rear wheel brake cylinder,
A branch brake pipe for the right front wheel brake cylinder on the side opposite to the right front wheel brake cylinder side of the first electromagnetic opening / closing valve or a brake pipe of the first system and a right rear wheel brake cylinder side of the second electromagnetic opening / closing valve. A first connection brake pipe connecting the branch brake pipe for the right rear wheel brake cylinder;
Branch brake piping for the right rear wheel brake cylinder on the side opposite to the right rear wheel brake cylinder side of the second electromagnetic on-off valve or the brake piping of the second system and the right front wheel brake cylinder side of the first electromagnetic on-off valve A second connection brake pipe that connects the right front wheel brake cylinder branch brake pipe of
The third electromagnetic on-off valve is disposed in the first connection brake pipe,
The fourth electromagnetic on-off valve is disposed in the second connection brake pipe;
The controller opens the first and second electromagnetic on-off valves when the hydraulic system is normal and the electric system is normal, closes the third and fourth electromagnetic on-off valves, and the first and second The first and second electromagnetic on-off valves are closed and the third and fourth electromagnetic on-off valves are opened at least when one of the hydraulic systems of the system is abnormal and when the electric system is abnormal. The hydraulic brake system according to claim 2.   When the hydraulic system is normal and the electrical system is normal, the brake fluid is supplied and discharged by the first system brake piping to the left and right front wheel brake cylinders, and the second system brake piping to the left and right rear wheel brake cylinders. The brake fluid is supplied and discharged by the control unit, and at least one of the left and right front wheel brake cylinders is provided at least when one of the hydraulic systems of the first and second systems is abnormal and when the electric system is abnormal. In contrast, the brake fluid is supplied and discharged through the first system brake piping, and the brake fluid is supplied and discharged from the left and right rear brake cylinders through the first system brake piping. And the left and right front wheel brake cylinders with the second system brake piping Hydraulic brake control method and controlling supply and discharge the brake fluid by the second system brake pipe for one left or right of the left and right rear wheel brake cylinders to control supply and discharge of the rake solution.

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