JPH069955B2 - Anti-skidding control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle braking system, and more particularly, to an anti-skid control device that prevents the wheels from being locked and the steering performance of the vehicle being impaired during braking.

2. Description of the Related Art A brake system for a vehicle is configured by connecting a master cylinder connected to a brake pedal and a wheel cylinder provided in a wheel brake mechanism by a pipe line. The anti-skid control device, for example, as described in Japanese Patent Publication No. Sho 49-28307, in the middle of the pipe line, with a valve for releasing the pressure oil in the wheel cylinder to the outside,
A wheel cylinder is provided with a pump for feeding pressure oil. That is, when wheel lock is detected, the pressure oil in the wheel cylinder is rapidly released, and then when the wheel needs to be braked again, the pump supplies hydraulic pressure to the wheel cylinder relatively gradually.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional anti-skid control device, the master cylinder and the pump for feeding the pressure oil to the wheel cylinder during the anti-skid control are simply connected in parallel to the wheel cylinder. Therefore, during the anti-skid control, the brake fluid pressurized by the pump flows back to the master cylinder side, which pushes up the brake pedal. As a result, there is a problem that the driver feels poor pedal feeling.

One way to solve this problem is to completely prevent the brake fluid pressurized by the pump from flowing toward the master cylinder during anti-skid control, for example, by providing a check valve. Can be considered,
In that case, the push-up of the brake pedal is completely eliminated, but the pedal reaction is also completely eliminated.Therefore, another problem arises in that it is difficult for the driver to confirm whether the anti-skid control is being performed during the anti-skid control. .

Therefore, the present invention has been made to solve these problems, and a driver confirms that anti-skid control is being performed while preventing excessive push-up of the brake pedal during anti-skid control. An object of the present invention is to provide an anti-skid control device that can give a pedal reaction to the extent possible.

Means for Solving the Problems In order to achieve the above-mentioned object, an anti-skid control device of the present invention is provided in a first pipe line connecting a master cylinder and a wheel cylinder, and in the middle of the first pipe line. When the anti-skid control is performed, a first switching valve that shuts off the first conduit is provided in parallel with the first switching valve, and when the pressure on the wheel cylinder side becomes higher than the pressure on the master cylinder side, A check valve that opens to the master cylinder side, a reservoir that stores brake fluid, a pressure source that pressurizes the brake fluid that is stored in the reservoir during anti-skid control to generate hydraulic pressure, and the first pipeline. A second pipe line connecting the downstream side of the first switching valve and the pressure source and the second pipe line are provided, and correspond to the pressure source, the wheel cylinder, and the reservoir. A second switching valve that has three ports and that selectively communicates the wheel cylinder with one of the pressure source or the reservoir; and a second switching valve in the second pipeline that is provided upstream of the second switching valve. And a throttle for limiting the flow rate of the brake fluid flowing from the pressure source.

In the anti-skid control device of the present invention, by adopting the above-mentioned configuration, the first switching valve shuts off the first pipe line connecting the master cylinder and the wheel cylinder during the anti-skid control, A closed circuit including a second pipe line composed of a pressure source, a wheel cylinder, and a reservoir is formed independently of the master cylinder, and the brake fluid circulates in the closed circuit. When the wheel cylinder pressure is higher than the master cylinder pressure due to pressure increase by the pressure source during anti-skid control, the check valve opens and the wheel cylinder pressure enters the master cylinder. Push up the pedal slightly to give the driver a pedal reaction to sense that anti-skid control is in effect.

In the present invention, during the anti-skid control, the brake fluid pressurized by the pressure source passes through the throttle and flows to the wheel cylinder. Therefore, when the above action occurs, the same throttle is applied to the master cylinder side. The brake fluid that has passed through will flow, and the hydraulic pressure of the brake fluid from the pressure source will be slightly attenuated and transmitted to the master cylinder.
The brake pedal will experience a relatively weak thrust force. Therefore, the driver does not receive an excessive and shocking pedal pushing force during the anti-skid control,
Deterioration of pedal feeling is prevented.

Examples The present invention will be described below with reference to illustrated examples.

FIG. 1 shows an embodiment of the present invention. This embodiment is an example in which the present invention is applied to a so-called FF vehicle, and the piping system of the brake system has X piping as well known, and the wheel cylinder 4 for the right front wheel and the wheel cylinder 7 for the left rear wheel have the same system. The brake oil is supplied from the conduit of the above, and the brake oil is supplied to the wheel cylinder 5 of the front left wheel and the wheel cylinder 6 of the rear right wheel from the conduit of the same system. Master cylinder 3 via vacuum booster 2 of brake pedal 1
The hydraulic pressure generated in the master cylinder 3 by depressing the brake pedal 1 passes through a pipeline as will be described later, and the wheel cylinders 4 of the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel are connected to each other. , 5, 6, 7, and the braking action is performed. As is conventionally known, the vacuum booster 2 is guided by the negative pressure generated in the intake manifold of the engine, and biases the push rod connected to the piston of the master cylinder 3 in response to the depression of the brake pedal 1 to operate the driver. Reduce the pedal effort on the brake pedal.

The master cylinder 3 has two pressure chambers (not shown) that discharge the brake fluid having the same pressure, and supply pipes 20 and 30 are connected to the respective pressure chambers. The supply pipe 20 is connected via a first switching valve 101 to a brake pipe 21 communicating with the wheel cylinder 5 for the left front wheel and a brake pipe 22 communicating with the wheel cylinder 6 for the right rear wheel, respectively. Brake pipe 2 via communication pipe 23 having
1 and is connected to the brake pipe 22 via a communication pipe 24 having a check valve 42. The first switching valve 101 is a three-port two-position valve, which connects the supply pipe 20 to the branch pipes 21 and 22 at the illustrated first position, and connects the supply pipe 20 to each branch pipe at a second position different from the illustrated position. Block from 21, 22. The check valves 41, 42 allow the brake fluid to flow into the brake pipes 21, respectively only when the pressure in the wheel cylinder 5 or 6 becomes higher than the pressure in the master cylinder 3.
Allowing flow only from 22 to the feed tube 20.

Similarly, the supply pipe 30 is also connected via a first switching valve 102 to a brake pipe 31 communicating with the wheel cylinder 4 for the right front wheel and a brake pipe 32 communicating with the wheel cylinder 7 for the left rear wheel, respectively, and a check valve. Communication pipe 25 having 43
Is connected to the brake pipe 31 via a communication pipe 26 having a check valve 44. Like the first switching valve 101, the first switching valve 102 is a three-port two-position valve, which connects the supply pipe 30 to the branch pipes 31 and 32 at the illustrated first position, and a second position different from that shown in the drawing. At, the supply pipe 30 is cut off from the branch pipes 31 and 32. The check valves 43 and 44 allow the brake fluid to flow into the brake pipes 31 and 32 only when the pressure in the wheel cylinder 4 or 7 becomes higher than the pressure in the master cylinder 3, respectively.
To allow flow only in the direction of the supply pipe 30.

Brake pipe 2 connected to the wheel cylinders 6 and 7 of the rear wheels
A conventionally known proportioning valve 103 is provided in the middle of 2 and 32, and when the hydraulic pressure exceeds a certain value, brake fluid having a pressure lower than the discharge pressure of the master cylinder 3 is applied to the wheel cylinders 6 of the rear wheels. It is designed to supply to 7.

With the above-described configuration, the normal braking action is performed, and the hydraulic pressure generated in the master cylinder 3 by depressing the brake pedal 1 is supplied to the wheel cylinder 5 of the left front wheel via the supply pipe 20 and the brake pipe 21, and to the supply pipe 20 and the brake. The supply pipe 3 is connected to the wheel cylinder 6 of the right rear wheel via the pipe 22.
0 to the wheel cylinder 4 for the right front wheel via the brake pipe 31, and to the wheel cylinder 7 for the left rear wheel via the supply pipe 30 and the brake pipe 32.

Next, a configuration for performing the unstick control will be described.

The variable displacement pumps 8 and 9 are rotationally driven by the motor 10, suck the brake oil from the branch pipes 51 and 61 of the oil pipes 50 and 60 that communicate with the reservoir 11, and supply the oil via the supply pipes 70 and 80, respectively. Wheel cylinders 4, 5, 6, 7
Supply to.

The branch pipe 71 of the supply pipe 70 can communicate with the branch pipe 33 of the brake pipe 31 via the second switching valve 104, and brake oil is prevented from flowing backward from the second switching valve 104 in the middle of the branch pipe 71. A check valve 91 and a throttle 92 for blocking are provided.
The second switching valve 104 is a three-port two-position valve, one discharge port is connected to the branch pipe 33, and the other discharge port is connected to the branch pipe 51 of the oil pipe 50. Therefore, the second switching valve 104 connects the branch pipe 71 to the branch pipe 33 at the illustrated first position, and connects the branch pipe 33 to the branch pipe 51 at a second position different from the illustrated position. Therefore, when the second switching valve 104 is in the first position, the brake fluid discharged from the pump 8 is supplied from the supply pipe 70 through the branch pipe 33 to the wheel cylinder 4, and the second switching valve 104 is in the second position. The brake fluid in the wheel cylinder 4 is released from the branch pipe 33 through the oil pipe 50 to the reservoir 11.

Similarly, the branch pipe 72 of the supply pipe 70 can communicate with the branch pipe 34 of the brake pipe 32 via the second switching valve 105, and the branch pipe 72 is provided with a check valve 93 and a throttle 94. One discharge port of the second switching valve 105 is connected to the branch pipe 34, and the other discharge port is connected to the branch pipe 52 of the oil pipe 50. Therefore, the second switching valve 105 connects the branch pipe 72 to the branch pipe 34 at the first position shown in the drawing to guide the brake oil discharged from the pump 8 to the wheel cylinder 7, and the second position different from that shown in the drawing. When the branch pipe 34 is in communication with the branch pipe 52, the brake fluid in the wheel cylinder 7 is stored in the reservoir 11
Release to.

The branch pipe 81 of the supply pipe 80 can communicate with the branch pipe 21 of the brake pipe 21 via the second switching valve 106, and the branch pipe 81 is provided with a check valve 95 and a throttle 96. One discharge port of the second switching valve 106 is connected to the branch pipe 27, and the other discharge port is connected to the branch pipe 53 of the oil pipe 50. Then, the second switching valve 106 connects the branch pipe 81 to the branch pipe 27 at the first position shown in the drawing to guide the brake oil discharged from the pump 9 to the wheel cylinder 5, and the second position different from that shown in the drawing. The branch pipe 27 is communicated with the branch pipe 53 to release the brake fluid in the wheel cylinder 5 to the reservoir 11.

Further, the same applies to the branch pipe 82 of the supply pipe 80.
It is connected to the branch pipes 28 and 54 through the switching valve 107, and the second
The switching valve 107 guides the brake fluid to the wheel cylinder 6 when it is in the first position, and the wheel cylinder 6 when it is in the second position.
The brake fluid inside is released to the reservoir 11.

The variable displacement pumps 8 and 9 are conventionally known radial piston type pumps, and the displacement can be changed by displacing a cam ring (not shown). A control valve 108 is provided to displace this cam ring. The control valve 108 is a three-port two-position valve. The suction port is connected to the branch pipe 73 of the supply pipe 70, the discharge port is connected to the branch pipe 55 of the oil pipe 50, and the transmission pipe 12 is connected to the other discharge port. Be connected. The transmission pipe 12 faces the end surface of the cam ring and guides hydraulic pressure to this end surface. The control valve 108 is guided to the pressure in the supply pipe 70 via the conduit 13 and switches in accordance with this pressure, so that the time branch pipe 73 in the first position shown in the drawing is transferred to the transfer pipe 12.
To guide the hydraulic pressure to the cam ring so that the pressure in the supply pipe 70 becomes high, and when the pressure is acting on the cam ring by communicating the transmission pipe 12 with the branch pipe 55 at the second position different from that shown in the drawing. release.

The variable displacement pumps 8 and 9 are driven by one motor 10 and have the same discharge flow rate. As described above, the cam rings of the pumps 8 and 9 are switched by the control valve 108, that is, the discharge flow rate A of the pumps 8 and 9 is relatively high below the discharge pressure P ₁ as shown in FIG.
The discharge pressure is set to be relatively low when the discharge pressure is P ₂ or higher, and the maximum discharge pressure is P ₂ . The broken line B in the figure indicates the discharge flow rate of the fixed displacement pump.

Since the pumps 8 and 9 change the discharge flow rate according to the discharge pressure as described above, the output C of the motor 10 changes according to the discharge pressure as shown in FIG. That is, the output of the motor 10 linearly increases the discharge pressure from 0 to P ₁ and reaches the maximum value M. Once the output pressure exceeds P ₁ , the motor output is halved and linearly increases to P _{2 and} then again reaches the maximum value. Reach M. Therefore, when the discharge pressure of the pumps 8 and 9 is low, a motor output much larger than the motor output in the case of the fixed displacement pump shown by the broken line D is obtained, and the flow rate at low pressure is increased without using a large motor. can do.

The suction side and the discharge side of the pumps 8 and 9 are connected by relief pipes 73 and 83, respectively.
Relief valves 109 and 110 are provided at 3 and 83, respectively. Relief valves 109 and 110 are each conduit 1
The pressure in the supply lines 30, 20 is introduced via 4, 15,
The relief pipes 73 and 83 are communicated in accordance with this pressure,
The discharge pressure of the pumps 8 and 9 is controlled. That is, the discharge pressure of the pumps 8 and 9 is substantially equal to the pressure inside the supply pipes 30 and 20.

The anti-skid control is performed when it is determined that one of the wheels is locked, in other words, when it is determined that the wheel deceleration or the slip ratio is too large. The wheel deceleration and slip rate are calculated by an electric control unit (ECU) (not shown) equipped with a microcomputer, and therefore a vehicle speed sensor (not shown) is provided near the wheels. When the ECU determines to start the anti-skid control, the first switching valve 10
When switching the first and second positions from the first position to the second position and performing anti-skid control, the second switching valves 104, 105, 106 and 107
Is switched according to the wheel deceleration and slip ratio. The second switching valves 105 and 107 for the rear wheels are always switched to the same position.

The operation of the apparatus of this embodiment will be described with reference to FIGS. 4 (a), (b) and (c).

In the non-actuated state where the braking action is not performed, the first switching valves 101 and 102 are in the first position. Therefore, when the brake pedal 1 is stepped on, the pressure oil discharged from the master cylinder 3 becomes the brake pipes 31, 21 and 2.
It is guided to each wheel cylinder 4, 5, 6, 7 through 2, 32, and the pressure in these wheel cylinders rises rapidly. That is, at time T _O , when the brake pedal 1 is stepped on, the wheel cylinder pressure P rapidly increases, and the wheel speed V _W rapidly decreases accordingly.
On the other hand, the vehicle body speed V _V also begins to decrease from time T ₁ ,
The decrease in the wheel speed V _W is more rapid.

When the wheel speed V _W becomes smaller than the reference speed V _I shown by the broken line in FIG. 4 (a), it is determined that the slip ratio is increasing, and the ECU outputs a command signal for anti-skid control. As a result, the first switching valve 101,
102 is switched to the second position, the motor 10 is driven, and the brake oil discharged from the pumps 8 and 9 is supplied to the wheel cylinders 4, 5, 6, and 7.
Pump discharge pressure begins to rise gradually from the time _{T 2,} becomes _{P 1} at time _{T 3,} then reaches _{P 2.} That is, as shown in FIG. 2, the discharge flow rates of the pumps 8 and 9 are _high from time T ₂ to T _3, and the discharge flow rates of the pumps 8 and 9 are low after time T ₃ . The broken line E in FIG. 4 (c) shows the change in the discharge pressure of the fixed displacement pump shown by the broken line B in FIG.

Simultaneously with the switching of the first switching valves 101, 102, one of the second switching valves 104, 105, 106, 107 corresponding to the wheel cylinder is switched to the second position in order to reduce the pressure in the predetermined wheel cylinder. The brake fluid in the wheel cylinder passes through the oil pipe 50 and the reservoir 11
Be released to. The pressure in the wheel cylinder rises from time T ₂ for a little while, but then begins to decrease. Then, when the degree of decrease in the wheel speed becomes weaker and it becomes necessary to increase the wheel cylinder pressure again, the second switching valve is switched to the first position, for example, at time T ₃ . As a result, the throttles 92, 94, 9 are connected to the wheel cylinders 4, 5, 6, 7.
Branch pipes 71, 72, 8 having a large flow resistance due to 6, 98
Brake fluid is gradually supplied via 1, 82, and the wheel cylinder pressure increases relatively slowly.

In the following, depending on the wheel deceleration or slip ratio, each second
The switching valves 104, 105, 106, 107 are switched, and the pressure in the wheel cylinders 4, 5, 6, 7 suddenly decreases or gradually increases. The anti-skid control ends when the vehicle is stopped or the brake switch is turned off, at which time the first switching valves 101 and 102 are switched to the first position.

In the above anti-skid control, the pump 8,
Since the discharge flow rate of 9 sharply increases immediately after the start of driving of the motor 10, as shown in FIG. 5, it is possible to make the time T ₄ to start increasing the pressure of the wheel cylinder as early as possible, and this time During the period from T ₄ to time T ₅ (A in FIG. 2) where the discharge flow rate of the pumps 8 and 9 is large, the wheel cylinder pressure can be increased more rapidly. Therefore, the pressure of the wheel cylinder can be quickly increased, and the responsiveness can be improved as compared with the case where the fixed displacement pump indicated by the broken line F is used.

When the pumps 8 and 9 cause a state in which the pressure of the wheel cylinders 4, 5, 6 and 7 is higher than the pressure of the master cylinder 3 during the anti-skid control, the check valves 41, 42 and 43 corresponding to the wheel cylinders are generated. , 44 are opened and the pressure of the wheel cylinder is transmitted to the inside of the master cylinder 3, and the pedal is slightly pushed up to give a proper pedal reaction to the driver, and the anti-skid control is surely detected.

In this case, if the driver pushes up excessively strongly, the driver feels uncomfortable. However, the brake fluid pressurized by the pumps 8, 9 passes through the throttles 92, 94, 96, 98 to the wheel cylinders 4, 5, 6, 6. 7, the pressure transmitted to the master cylinder 3 is also attenuated by these throttles, so that the brake pedal 1 receives a relatively weak thrust force. Therefore, the driver does not receive an excessive and shocking push-up force of the pedal during the anti-skid control, and deterioration of the pedal feeling is prevented.

As described above, according to the present invention, during anti-skid control, the first switching valve shuts off the conduit connecting the master cylinder and the wheel cylinder, and the pressure of the wheel cylinder becomes higher than the pressure of the master cylinder. Only when it becomes, it is possible to transmit the hydraulic pressure of the pressure source attenuated by the throttle to the master cylinder and give a relatively small pedal reaction to the driver to make sure that the anti-skid control is being performed, As a result, a pleasant pedal feeling can be provided without making the driver feel an uncomfortable impact of pushing up the pedal.

Also, in the normal braking state, the hydraulic pressure generated in the master cylinder is supplied to the wheel cylinder without passing through the throttle, so that a large braking force can be obtained quickly, while at the time of anti-skid control, it flows from the pressure source to the wheel cylinder. Since the flow of the pressurized brake fluid is restricted by the throttle, it is possible to prevent the wheel from re-locking by suppressing a sudden increase in the brake pressure during the pressure increase after the pressure reduction during the anti-skid control. .

Further, the second switching valve according to the present invention has three ports, and the pressure of the wheel cylinder can be increased or decreased only by performing the operation of switching the second switching valve during the anti-skid control. The overall size can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the relationship between the discharge pressure of the pump and the discharge flow rate, and FIG. 3 is a graph showing the relationship of the motor output with respect to the discharge pressure of the pump, 4 (a) is a graph showing changes in vehicle speed and wheel speed, FIG. 4 (b) is a graph showing changes in wheel cylinder pressure, and FIG. 4 (c) is a graph showing changes in pump discharge pressure. The graph, FIG. 5, is a graph showing changes in the pressure of the wheel cylinder. 4, 5, 6, 7 ... Wheel cylinders, 8, 9 ... Variable capacity pump (pressure source), 11 ... Reservoir, 104, 105, 1
06, 107 ... Switching valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Imani 1-1, Showa-cho, Kariya city, Aichi Prefecture Nihon Denso Co., Ltd. (72) Inventor Akira Kuno 1-1-chome, Showa town, Kariya city, Aichi prefecture Sozo Co., Ltd. (72) Inventor Yoshihisa Nomura 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (1)

[Claims] 1. A first pipe line connecting a master cylinder and a wheel cylinder, a first switching valve provided in the middle of the first pipe line, and shutting off the first pipe line during anti-skid control, A check valve that is provided in parallel with the first switching valve and that opens to the master cylinder side when the pressure on the wheel cylinder side becomes higher than the pressure on the master cylinder side; a reservoir that stores brake fluid; A pressure source that pressurizes brake fluid stored in the reservoir to generate hydraulic pressure during skid control, and a second pipeline that connects the downstream side of the first switching valve in the first pipeline to the pressure source. And has three ports provided in the second conduit and corresponding to the pressure source, the wheel cylinder, and the reservoir, and the wheel cylinder is connected to the pressure source or the reservoir. A second switching valve that selectively communicates with one side; and a throttle that is provided upstream of the second switching valve in the second conduit and limits the flow rate of brake fluid flowing from the pressure source. An anti-skid control device characterized in that