JPH04266559A - Liquid pressure control device for hydraulic brake for vehicle - Google Patents

Abstract

PURPOSE:To perform proper brake with ordinary operation feeling during brake operation in the middle of or immediately after traction control by rapidly reducing the liquid pressure of a wheel cylinder exerted through traction control, in a liquid pressure control device having an antiskid control means and a traction control means. CONSTITUTION:A switching valve 22 for communicating a wheel cylinder 42 with a master cylinder reservoir 41a by detouring around a switching valve 11 for antiskid control during the generation of a liquid pressure in a master cylinder 41 and in the middle of or immediately after traction control is provided. Pressure liquid of the wheel cylinder 42 is returned to a master cylinder reservoir 41a of the wheel cylinder 42 without passing through the orifice on the pressure reduction side of the switching valve 11 for the antiskid control.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure control device for a hydraulic brake for a vehicle.

0002

[Prior Art] As shown in Japanese Unexamined Patent Publication No. 2-231256 as a type of hydraulic pressure control device for hydraulic brakes for vehicles, an anti-static brake system is installed between a master cylinder, a wheel cylinder of a driving wheel, and a reservoir. There is a hydraulic control device consisting of skid control means and traction control means. Anti-skid control is intended to prevent the wheels from locking up and sliding on the road surface when the braking torque applied to the wheels of a running vehicle is excessive in relation to the friction coefficient of the road surface. However, traction control is a system in which when the drive torque applied to the drive wheels when the vehicle is accelerating is too large in relation to the coefficient of friction of the road surface, the drive wheels may slip on the road surface and the vehicle will not accelerate effectively. It is intended to prevent the phenomenon from occurring.

[0003]In this type of conventional hydraulic pressure control device for a hydraulic brake, the anti-skid control means includes a first switching valve that selectively communicates the wheel cylinder with the master cylinder and the reservoir; a check valve that is provided to bypass the first switching valve and allows flow of only the pressure fluid flowing out from the wheel cylinder; and a discharge valve that is provided between the wheel cylinder and the reservoir to discharge the pressure fluid from the wheel cylinder. a pump, and the traction control means includes a second switching valve for selectively communicating the anti-skid control means with the master cylinder and the master cylinder reservoir; The vehicle is configured to include a supply pump that supplies pressurized fluid to the wheel cylinder through skid control means.

Therefore, when braking a traveling vehicle in this hydraulic pressure control device, the hydraulic pressure generated in the master cylinder is applied to the second switching valve constituting the traction control means and the first switching valve constituting the anti-skid control means. It is supplied to the wheel cylinder through the switching valve, and the wheels are braked. The slip rate of the wheels during braking is detected, and if the slip rate exceeds a preset value, the first switching valve is operated based on the detection signal of the slip rate, and the discharge pump is activated. The pressure fluid in the wheel cylinder is drained,
The braking torque applied to the wheels is reduced to prevent the wheels from becoming locked. Thereafter, when the slip ratio of the wheels decreases or the slip is eliminated, the first switching valve is operated to return to the normal state.

- On the other hand, the slip rate of the wheels is detected during acceleration of the vehicle, and if the slip rate exceeds a preset value, the second switching valve operates to switch based on the detection signal of the same slip rate. The master cylinder is
Pressure fluid is applied from the reservoir to the wheel cylinder through the second switching valve and the first switching valve to brake the wheel and prevent excessive slip during acceleration. Then, when the wheel slip rate decreases or the slip is eliminated,
The second switching valve switches and returns to the normal state, and the first switching valve also switches, and the pressure fluid in the wheel cylinder is discharged by the action of the discharge pump, reducing the pressure in the wheel cylinder and returning to the normal state. Further, after the pressure fluid is discharged, the first switching valve is operated to return to the normal state.

[0006] In both of these controls, the pressure fluid is supplied to the wheel cylinder through the pressure increase side orifice which the first switching valve has on the upstream side, and the pressure fluid is discharged from the wheel cylinder through the pressure increasing side orifice which the first switching valve has on the downstream side. This is done through a vacuum side orifice on the side.

[0007]

[Problems to be Solved by the Invention] In this type of hydraulic pressure control device, the pressure fluid in the wheel cylinder is discharged first when the wheel cylinder is depressurized to return to the normal state after traction control is completed. However, since the pressurized liquid is passed through the pressure reducing side orifice, it takes a considerable amount of time to discharge the pressurized liquid from the wheel cylinder. Ejection time is, for example, 500ms ~
It takes about 1 second. Therefore, if pressure fluid from the master cylinder is applied to the wheel cylinders to brake the vehicle during this period, the pressure fluid still remains in the wheel cylinders, so for example, the amount of depression of the brake pedal to operate the master cylinder Unlike the relationship in which the hydraulic pressure applied to the wheel cylinders is set, excessive braking torque is applied to the vehicle, impairing the brake operation feeling. Therefore, the object of the present invention is to
It is an object of this type of hydraulic pressure control device to quickly reduce the pressure in the wheel cylinder after traction control is completed.

[0008]

[Means for Solving the Problems] The present invention provides a hydraulic pressure control device of the type described above, in which the traction control means is provided with a bypass line that bypasses the supply pump, and the bypass line is provided with a bypass line that bypasses the supply pump. This device is characterized in that it is equipped with a normally closed third switching valve that is opened when pressure is generated.

[0009]

[Operation of the invention] In the hydraulic pressure control device having such a structure,
When hydraulic pressure is generated in the master cylinder, the third switching valve is opened in response to the generation of hydraulic pressure, so hydraulic pressure is generated in the master cylinder to brake the vehicle while traction control is continuing or immediately after the traction control ends. In this case, before the same pressure fluid is applied to the wheel cylinder, the check valve with which the wheel cylinder communicates communicates with the master cylinder reservoir through the third switching valve and is opened to the atmosphere. The hydraulic pressure is quickly discharged through the check valve.

0010

[Effects of the Invention] Therefore, according to the hydraulic pressure control device, even if the vehicle is braked while traction control is continuing or immediately after the traction control ends, no pressure fluid remains in the wheel cylinders, so the braking state remains normal. The vehicle can be braked accurately with normal operation feeling.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic pressure control device for a vehicle hydraulic brake according to the present invention. The hydraulic pressure control device includes anti-skid control means 10 and traction control means 20 for the rear wheels of the vehicle, and anti-skid control means 30 for the front wheels. Both control means 10 and 20 for the rear wheels are interposed between the master cylinder 41 and the wheel cylinder 42 of the rear wheel of the vehicle, and the anti-skid control means 30 for the front wheel is interposed between the master cylinder 41 and the wheel cylinder 43 of the front wheel. It is interposed in between.

The anti-skid control means 10 is the first of the pair.
Electromagnetic switching valve 11, -pair of first check valves 12, discharge pump 1
3 and a reservoir 14. Each of the first electromagnetic switching valves 11 corresponds to a first switching valve of the present invention. The anti-skid control means 10 is connected to the master cylinder 41 via a hydraulic line 44a and the traction control means 20, and to the master cylinder reservoir 41a via a hydraulic line 44b and the traction control means 20. Each first electromagnetic switching valve 11 is interposed in a hydraulic pipe 44c connecting the traction control means 20 to each wheel cylinder 42, and each check valve 12 is connected in parallel with each first electromagnetic switching valve 11. It is interposed in the hydraulic pressure conduit 44c. The reservoir 14 is connected to the traction control means 20 via a hydraulic line 44d.
A discharge pump 13 is interposed at d. In the anti-skid control means 10, the wheel cylinder 4 of each rear wheel
A first electromagnetic switching valve 11 and a check valve 12 are provided for each wheel cylinder 42, and a discharge pump 13 and a reservoir 14 are shared by each wheel cylinder 42.

The first electromagnetic switching valve 11 is a three-position switching valve, and has a pressure increasing position where the master cylinder 41 is connected to the wheel cylinder 42, a pressure reducing position where the wheel cylinder 42 is connected to the reservoir 14, and a neutral position where each connection is cut off. It switches between three positions. The electromagnetic switching valve 11 includes a pressure increasing orifice 11a and a pressure reducing orifice 11b. The check valve 12 functions to restrict the flow of pressure fluid from the upstream side of the hydraulic pressure pipe 44c, and to allow the flow of pressure fluid from the downstream side of the hydraulic pressure pipe 44c. The operation of the anti-skid control means 10 is controlled by an electronic control unit ECU mainly composed of a microcomputer.

Thus, the traction control means 20 includes a second electromagnetic switching valve 21, a third electromagnetic switching valve 22, and a supply pump 2.
3 and a relief valve 24. The second electromagnetic switching valve 21 and the third electromagnetic switching valve 22 correspond to the second switching valve and third switching valve of the present invention, and are two-position switching valves. The second electromagnetic switching valve 21 is connected to the master cylinder 41 via a hydraulic line 44a, and to the master cylinder reservoir 41a via a hydraulic line 44b, and controls the anti-skid control means 10 by a switching operation. Selectively connects to cylinder 41 and master cylinder reservoir 41a. Third electromagnetic switching valve 22, supply pump 2
3 and the relief valve 24 are interposed in parallel with each other in the hydraulic pressure line 44b.

The third electromagnetic switching valve 22 functions to bypass the supply pump 23 and communicate the second electromagnetic switching valve 21 to the master cylinder reservoir 41a, and the supply pump 23 supplies pressurized fluid from the reservoir 41a to each wheel cylinder. 42, and the relief valve 24 functions to restrict the pressure of the pressurized liquid supplied from the supply pump 23 from rising above a predetermined level. The operation of the traction control means 20 is controlled together with the anti-skid control means 10 by an electronic control unit ECU.

Furthermore, the anti-skid control means 3 for the front wheels
0 has the same configuration as the anti-skid control means 10 for rear wheels, and the operation is controlled by the electronic control unit ECU in the same manner as the anti-skid control means 10, so detailed explanations of the configuration and operation will be omitted. do.

In the hydraulic pressure control device having such a configuration, the anti-skid control means 10 and the traction control means 20 for the rear wheels are controlled and operated by the electronic control unit ECU as described below, and control the brake fluid pressure to each wheel cylinder 42. Control. FIG. 1 shows the state when the vehicle is stopped and when the vehicle is normally running. It communicates with the wheel cylinder 42 through. Further, in this state, the discharge pump 13 and the supply pump 23 have stopped driving.

When the brake pedal 45 is depressed to brake the vehicle in such a state, pressure fluid is generated in the master cylinder 41, and the pressure fluid is applied to each wheel cylinder 42, thereby braking each wheel. On the other hand, the electronic control unit ECU starts anti-skid control based on the detection signal of the depression operation of the brake pedal 45, and switches the third electromagnetic switching valve 22 based on the detection signal of the hydraulic pressure generated in the master cylinder 41. The slip ratio of each rear wheel is calculated, and if the slip ratio exceeds the set value, each rear wheel is operated.
The electromagnetic switching valve 11 is switched to the pressure reducing position and the discharge pump 13 is driven.

As a result, the pressure fluid in the wheel cylinder 42 is discharged to the reservoir 14, and the fluid pressure in the wheel cylinder 42 is reduced. When the rotational speed of the rear wheels is restored, the first electromagnetic switching valve 11 is switched to the neutral position or the pressure increasing position, and the slip ratio of the rear wheels is controlled to be equal to or less than the set value. Note that the pressure fluid discharged to the reservoir 14 is transferred to the master cylinder 4.
When the hydraulic pressure in the cylinder 1 decreases, it is returned to the master cylinder 41 via the hydraulic line 44d, the second electromagnetic switching valve 21, and the hydraulic line 44a.

When the depression of the brake pedal 45 is released, the electronic control unit ECU switches the first electromagnetic switching valve 11 to the pressure increasing position based on the release signal, and
The drive of the discharge pump 13 is stopped to complete the anti-skid control. During this time, the hydraulic pressure in the master cylinder 41 decreases, and the pressure liquid in the wheel cylinder 42 flows back to the master cylinder 41 via the check valve 12, the hydraulic line 44c, the second electromagnetic switching valve 21, and the hydraulic line 44a. Further, the third electromagnetic switching valve 22 is switched and returned to the position shown in FIG. As a result, the brake is deactivated and the vehicle is released from braking. The anti-skid control described above is similarly performed in the anti-skid control means 30 for the front wheels.

On the other hand, when the accelerator pedal is depressed to start or accelerate the vehicle, the electronic control unit ECU starts traction control based on the detection signal of the operation and calculates the slip rate of the rear wheels. The electronic control unit ECU switches the second electromagnetic switching valve 21 and drives the supply pump 23 when the slip ratio of the rear wheels exceeds a set value. As a result, the master cylinder reservoir 41
Pressure fluid is applied from a to the wheel cylinder 42 via the hydraulic pressure pipe 44b, the supply pump 23, the second electromagnetic switching valve 21, and the hydraulic pressure pipe 44c, and the rear wheel is braked to reduce the slip rate to a set value or less. I do.

When the slip ratio of the rear wheels is controlled to be below the set value, the electronic control unit ECU switches the first electromagnetic switching valve 11 to the pressure reducing position based on the detection signal of the slip ratio and drives the exhaust pump 13. and supply pump 23
Stops driving. As a result, the wheel cylinder 42
The pressure fluid passes through the first electromagnetic switching valve 11, the discharge pump 13, the hydraulic line 44d, the second electromagnetic switching valve 21, the relief valve 24, and the hydraulic line 44b, and then reaches the master cylinder reservoir 41a.
Reflux to. Thereafter, the first and second electromagnetic switching valves 11 and 21 are switched and returned to normal operation, and the drive of the discharge pump 13 is stopped to complete the traction control.

When the brake pedal 45 is depressed during the above-described traction control, the electronic control unit ECU switches the third electromagnetic switching valve 2 based on the detection signal of the same operation.
At the same time, the anti-skid control means 10 and the traction control means 20 are returned to the state shown in FIG. As a result, the wheel cylinder 42 communicates with the master cylinder reservoir 41a through the instantaneous check valve 12, the hydraulic line 44c, the second electromagnetic switching valve 21, the third electromagnetic switching valve 22, and the hydraulic line 44b. The pressure fluid instantly flows back to the master cylinder reservoir 41a, and the wheel cylinder 42 becomes at atmospheric pressure. As a result, the brake returns to its normal state, allowing the brake to be operated without impairing the operating feel.

As described above, in the hydraulic pressure control device, the third electromagnetic switching valve 22 is switched based on the generation of hydraulic pressure in the master cylinder 41 to instantly communicate the wheel cylinder 12 with the master cylinder reservoir 41a. Therefore, when the brake pedal 45 is operated, the pressure fluid applied to the wheel cylinder 42 during traction control can be quickly discharged without passing through the pressure reducing side orifice 11b of the first electromagnetic switching valve 11. can. Therefore, when the brake is operated during the traction control or immediately after the traction control is completed, the hydraulic pressure in the wheel cylinder 12 can be quickly discharged and the normal brake operation state can be restored. You can perform brake operations based on feeling and brake the vehicle accurately.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a hydraulic pressure control device according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10... Anti-skid control means for rear wheels, 11... First electromagnetic switching valve, 12... Check valve, 13... Discharge pump, 14... Reservoir, 20... Traction control means for rear wheels, 21... Second
Electromagnetic switching valve, 22... Third electromagnetic switching valve, 23... Supply pump, 30... Front wheel anti-skid control means, 41... Master cylinder, 41a... Master cylinder reservoir, 42...
Wheel cylinder, 45...Brake pedal.

Claims (1)

[Claims] 1. A master cylinder, an anti-skid control means and a traction control means disposed between a wheel cylinder of a drive wheel and a reservoir, the anti-skid control means selectively controlling the wheel cylinder between the master cylinder and the reservoir. a first switching valve that communicates with the first switching valve, a check valve that is provided to bypass the first switching valve and allows flow of only the pressure fluid flowing out from the wheel cylinder, and a check valve that is provided between the wheel cylinder and the reservoir. a discharge pump for discharging pressurized fluid from the wheel cylinder, and the traction control means includes a second switching valve that selectively communicates the anti-skid control means with the master cylinder and the master cylinder reservoir;・
In a hydraulic pressure control device for a vehicle hydraulic brake comprising a supply pump that supplies pressurized fluid from a reservoir to the wheel cylinder through the anti-skid control means, a bypass conduit that bypasses the supply pump to the traction control means. A hydraulic pressure control device for a hydraulic brake for a vehicle, characterized in that the bypass pipe is provided with a normally closed third switching valve that is opened when hydraulic pressure is generated in the master cylinder. .