JPH03189258A - Antiskid type brake device - Google Patents

Abstract

PURPOSE:To improve the reliability of braking operation by operating one of two flow controllers provided in respective wheel cylinders to reduce braking liquid in antiskid control when road surfaces mu at the left and right wheel sides differ from each other. CONSTITUTION:Flow controllers 26, 86 and a two-position valves 28, 90 are provided on the way of liquid paths leading to wheel cylinders 16, 18 for two sets of front and rear wheels in the diagonal positional relation to each other, while direction change-over valves 134, 170 are provided between pilot paths 72, 73 and 110, 111 and reservoirs 130, 172 connected to a pilot chamber 54 of the flow controllers 26, 88. When a locking tendency takes place in the left rear wheel on a split road surface for example, the two-position valve 90 on the left rear wheel side is changed over to a pressure reducing position. Accordingly, the pilot chamber 54 of the flow controller 26 on the right rear wheel side is shut off from the wheel cylinder 16 by the direction change-over valve 134 to communicate to the reservoir 130 so that the liquid pressure in the wheel cylinder 16 at the right rear wheel side is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an anti-skid brake system for a vehicle, and in particular, the present invention relates to an anti-skid brake system for a vehicle, and in particular, the brake is applied when the coefficients of friction between the left and right wheels and the road surface are significantly different. This invention relates to an improvement in technology for suppressing a sudden increase in the yaw moment of a vehicle when the vehicle is forced to move.

BACKGROUND ART Anti-skid control is a control performed to prevent wheels from locking during vehicle braking, and an example of an anti-skid type brake device capable of performing this anti-skid control is disclosed in Japanese Patent Publication No. 56-28738. has been disclosed.

The present applicant previously developed the following device as one of the anti-skid type brake devices.

This consists of ``(a) two electromagnetic valve devices each connected between a hydraulic pressure source and each wheel cylinder of the left and right wheels;
(b) an anti-skid control device that anti-skid controls the hydraulic pressure of each wheel cylinder via a respective electromagnetic valve device based on the lock tendency of each of the left and right wheels;
) The hydraulic pressure is normally controlled by the operation of a valve that is connected between the hydraulic pressure source and each wheel cylinder and receives the hydraulic pressure of the hydraulic pressure source and the hydraulic pressure of each wheel cylinder in opposite directions as pilot pressure. This system allows brake fluid to flow at a large flow rate from the pressure source to each wheel cylinder, but during anti-skid control, the brake fluid flow rate is reduced as the hydraulic pressure difference between the hydraulic pressure source and each wheel cylinder increases. This is an anti-skid type brake device including a control device.

The hydraulic pressure source is, for example, known as a brake mask cylinder, which generates hydraulic pressure at a level corresponding to the operation of an operating member such as a brake pedal.

Further, the wheel cylinder operates a brake for suppressing rotation of the wheel.

In addition, the solenoid valve device has a pressure increasing position where the wheel cylinder is cut off from the reservoir and communicated with the hydraulic pressure source, a pressure reducing position where the wheel cylinder is cut off from the hydraulic pressure source and communicated with the reservoir, and a pressure holding position where the wheel cylinder is not communicated with any of them. It is composed of a 3-position valve that can be switched to 2-position valves and a 2-position valve that does not have a pressure holding position. In addition, a solenoid valve device is configured by a combination of multiple valves, such as a combination of two solenoid on-off valves provided on the hydraulic pressure source side and a reservoir side, or a combination of an electromagnetic directional control valve and an electromagnetic on-off valve. In some cases.

Further, the anti-skid control device is generally configured mainly using a computer.

Further, some aspects of the flow rate control device are disclosed in Japanese Patent Application No. 1983-225860 and Japanese Patent Application No. 63
-45423 specification etc.

The respective coefficients of friction between the left and right wheels and the road surface may be significantly different. For example, this is the case when a vehicle runs on a straddle road where the left and right sides have different coefficients of friction.

When the brakes are applied with a large difference in the friction coefficients, the wheel with the higher coefficient of friction will have a higher μ of the left and right wheels.
A large braking force difference occurs between the side wheels and the lower low-μ side wheel, creating a yaw moment that tends to rotate the vehicle about a vertical axis passing through its center of gravity. For example, at the beginning of one-sided control when strong braking is applied on a cross road and anti-skid control is performed only on either the left or right wheel, the braking force on the low-μ side wheel on which anti-skid control is performed rapidly increases. On the other hand, the braking force on the high-μ side wheel where anti-skid control is not performed increases to a height corresponding to the brake operation, so the difference in braking force between the left and right wheels rapidly increases, and as a result, the vehicle The yaw moment suddenly increases.

Furthermore, if the friction coefficients of the surfaces of the left and right wheels are the same, but the friction coefficients of the road surfaces that these wheels come into contact with are different,
Since the difference in braking force generated between the left and right wheels is uniquely determined by the difference in hydraulic pressure between the respective wheel cylinders, it is possible to estimate the difference in braking force and thus the yaw moment based on the hydraulic pressure difference. For example, when the hydraulic pressure in each wheel cylinder changes as shown in Fig. 4, the hydraulic pressure difference changes as shown in the graph shown in Fig. 5 when pressure increase is not suppressed, and the change in the hydraulic pressure difference occurs. is the change in yaw moment.

A technique for suppressing a rapid increase in yaw moment during one-sided control is disclosed in the aforementioned Japanese Patent Publication No. 56-28738. Normally, during one-sided control, this would cause the solenoid valve device corresponding to the high μ side wheel, which is in the pressure increasing position (the normal position where the anti-skid control device does not perform anti-skid control), to gradually increase the wheel cylinder fluid pressure. By slowly increasing the pressure, the high μ side wheel cylinder and the low μ side
This technology allows the hydraulic pressure difference between the side wheel cylinder and the side wheel cylinder to gradually increase. If this technique is applied to the case shown in Fig. 4, the pressure increase gradient of the high-μ side wheel cylinder hydraulic pressure will become smaller than in the case of Fig. 4, that is, when pressure increase is not suppressed, as shown in Fig. As shown in Fig. 5 when the pressure increase is suppressed, the pressure difference increases gradually compared to when the pressure increase is not suppressed.
This suppresses the rapid increase in yaw moment.

Problems to be Solved by the Invention However, in the device described in the above publication, a solenoid valve device is used to suppress the increase in yaw moment, so an electric control section ( (including the part that controls the solenoid valve device of the anti-skid control device)
There is a problem in that the control speed of the solenoid valve device may not be sufficiently determined due to the increased burden on the operator. for example,
If the electric control unit is mainly composed of a computer, the program for controlling the solenoid valve device becomes too large, and the processing speed of the entire program decreases.
The control speed of the solenoid valve device cannot be determined sufficiently.

The present invention has been made with the object of solving the above-mentioned problem in an anti-skid type brake device equipped with the above-mentioned flow control device, by suppressing a sudden increase in yaw moment using the flow control device. It is.

Means for Solving the Problems And, the gist of the present invention is to provide an anti-skid type brake device including the two electromagnetic valve devices, an anti-skid control device and two flow rate control devices, with an anti-skid type brake device having a structure between each of the left and right wheels and the road surface. A flow rate reduction device is provided for reducing the flow rate of the brake fluid when the respective friction coefficients of the brake fluid differ by more than a set amount, the one corresponding to the wheel having the higher friction coefficient among the two flow rate control devices.

The flow reduction device can take various forms.

For example, a road surface μ sensor that detects each friction coefficient between each of the left and right wheels and the road surface, and a determination means that determines whether each friction coefficient differs by more than a set amount based on the detection result of the road surface μ sensor. It is possible to adopt a mode including the following.

Also, during one-sided control in which the anti-skid control device performs anti-skid control only on either the left or right wheels (this is the case in the present invention when the coefficient of friction between each of the left and right wheels and the road surface differs by more than a set amount). It is also possible to take a mode in which the system operates in the following mode. In this aspect, the determination as to whether or not one-sided control is being performed is made based on, for example, an electric signal that the anti-skid control device outputs to each solenoid valve device, or based on the hydraulic pressure of each wheel cylinder of the left and right wheels. You can also do it as you like.

In addition, a mode that operates during one-sided control is, for example, in a flow control device, the pilot chamber in which the wheel cylinder hydraulic pressure acts as a pilot pressure and the wheel cylinder are isolated from each other, and part or all of the brake fluid is released from the pilot chamber. By moving the valve of the flow control device in the direction of decreasing the flow path area, the pressure increase gradient of the wheel cylinder hydraulic pressure can be reduced. It is desirable that the valve be moved in a direction that reduces the flow path area by acting in a direction that reduces the area. Note that the flow rate reduction device can be an electricity bill or can be a pilot type like the flow rate control device.

In addition, the flow rate reduction device operates not only during one-sided control, but also during both-side control, where the anti-skid control device performs anti-skid control on both left and right wheels. It is also possible to adopt a mode in which the hydraulic pressure difference is reduced.

Operation In the device of the present invention, when the friction coefficients between each of the left and right wheels and the road surface differ by more than a set amount, one of the two flow rate control devices corresponds to the high μ side wheel with the higher friction coefficient. By using this, the flow rate of brake fluid flowing from the hydraulic pressure source toward the high-μ side wheel cylinder is reduced, and as a result, the pressure increase gradient of the high-μ side wheel cylinder is reduced, and the left and right wheels are This suppresses the sudden increase in the difference in braking force that occurs between the two, and the increase in yaw moment.

Effects of the Invention As described above, according to the present invention, a rapid increase in yaw moment is suppressed by using the flow control device provided for accurately performing anti-skinned control. The load on the electric control section is no longer increased, and the solenoid valve device can be controlled with desired precision.

Flow control devices typically ensure that brake fluid flows from the hydraulic pressure source toward the wheel cylinders even when the valve minimizes flow area. Therefore, even if the flow rate reducing device is activated at a time when it should not be activated for some reason to minimize the flow path area, the hydraulic pressure source and the wheel cylinder will not be cut off from each other. Even in the first case, the brake will always work, and the reliability of the brake system will be improved.

EXAMPLES Below, several examples in which the present invention is applied to an anti-skid brake system for a four-wheel vehicle equipped with a two-position valve as a solenoid valve system will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a brake pedal as an operating member, which is linked via a booster 12 to a mask cylinder 14 as a hydraulic pressure source. The mask cylinder 14 generates hydraulic pressure of equal height in two independent pressurizing chambers in response to the operating force of the brake pedal IO. The hydraulic pressure in one pressurizing chamber is transmitted to the wheel cylinders of the brakes provided on the front left wheel and the rear right wheel, and the hydraulic pressure in the other pressurizing chamber is provided on the front right wheel and the rear left wheel, respectively. It is transmitted to the brake wheel cylinder. In FIG. 1, only the wheel cylinder 16 for the right rear wheel and the wheel cylinder 18 for the left rear wheel are illustrated, and the following explanation will be given only for the left and right rear wheels.

First, the right rear wheel system will be explained. The wheel cylinder 16 of the right rear wheel is connected to the mask cylinder 14 by liquid passages 19, 20 and 22, and a flow control device 26 and a two-position valve 28 are provided in series therebetween.

The two-position valve 28 is always connected to the liquid passage 20 as shown in FIG.
The mask cylinder 14 is in a pressure increasing position that allows the hydraulic pressure in the mask cylinder 14 to be transmitted to the wheel cylinder 16, but when the solenoid 30 is energized, the liquid passage 22 is cut off from the liquid passage 20. At the same time, the brake fluid in the wheel cylinder 16 is brought into communication with the reservoir 32 through the reservoir passage 31, and becomes a reduced pressure position that allows the brake fluid in the wheel cylinder 16 to be discharged into the reservoir 32. This solenoid 30 is a CPU,
It is controlled by a control device 34 mainly composed of a computer including ROM, RAM, and a bus. Connected to the control device 34 are a wheel speed sensor 38 that detects the rotational speed of a disc rotor 36 that rotates together with the right rear wheel, that is, the rotational speed of the right rear wheel, and a vehicle speed sensor 39 that detects the vehicle speed that is the running speed of the vehicle body. The control device 34 estimates the slip rate of the right rear wheel from the detection results of the wheel speed sensor 38 and the vehicle speed sensor 39, and controls the two-position valve 28 so that this slip rate falls within an appropriate range.

The brake fluid discharged from the wheel cylinder 16 to the reservoir 32 by switching the two-position valve 28 to the pressure reduction value 1 is returned to the fluid passage 19 via the pump passage 42 by the pump 40.

Check valves 43, 44 and 45 are provided in the middle of the pump passage 42.
are installed in series. The opening pressures of these check valves 43 to 45 are all set so small that they can be ignored.

Flow control device 26 includes a control piston 48 slidably fitted by the housing. control piston 48
is a cylindrical member, and the space inside the housing is partitioned by the control piston 48 into a liquid chamber 52, a first pilot chamber 54, and a second pilot chamber 56. Annular grooves 62 and 64 are respectively formed in the inner circumferential surface of the housing, and when the control piston 48 is in the original position shown in FIG. does not exert a substantial throttling effect and maximizes the flow area of the brake fluid toward the annular grooves 62 to 64, but if the control piston 48 moves forward against the biasing force of the spring 70, the throttling effect is Specifically, the flow path area is controlled so that it becomes smaller as the control piston 48 advances, and when the control piston 48 is at the forward end position, the flow path area is set to the minimum (not O). ).

The flow rate of the brake fluid passing through the flow control device 26 is controlled by the wheel cylinder 1 by actuation of the control piston 48 based on the hydraulic pressure difference between the first pilot chamber 54 and the second pilot chamber 56.
The hydraulic pressure of No. 6 is controlled to increase at a constant rate regardless of the hydraulic pressure difference, and in this embodiment,
The control piston 48 functions as a valve.

The first pilot chamber 54 has pilot passages 72 and 73
is connected to the liquid passage 22 by the second pilot chamber 56.
is connected to the portion of the pump passage 42 between the check valves 44 and 45 by a pilot passage 74 .

The second pilot chamber 56 is also connected to the liquid passageway 20 by a pilot passageway 76. A check valve 80 is provided in the pilot passage 76.

This check valve 80 is connected from the liquid passage 20 to the second pilot chamber 56.
It allows brake fluid to flow in the direction of the brake fluid, but prevents it from flowing in the opposite direction. The opening pressure of the check valve 80 is
It is set to a value equal to the hydraulic pressure difference ΔP that is estimated to occur between the liquid passages 20 and 22 due to the throttling action of the two-position valve 28 when the brake pedal 10 is depressed most rapidly. The flow rate control device 26 and the check valve 80 are described in Japanese Patent Application No. 1-78783 filed by the present applicant.
Since it is described in detail in the specification of No. 1, the explanation will be omitted here.

The right rear wheel system has been described above, but the left rear wheel system is also similar to the liquid passages 82, 84 and 86. Flow rate control device 88
, 2-position valve 90. Reservoir passage 92, reservoir 94. Wheel speed sensor 98. Pump 100, pump passage 102.
Check valves 104, 106 and ios, pilot passage 1
10,111° 112 and 114 and a check valve 116 having an opening pressure equal to ΔP. In addition, 2
The solenoid 30 of the position valve 90 is connected to the control device 34, and the left rear wheel is also anti-skid controlled by the control device 34.

The right rear wheel system further includes a pilot type directional control valve 13 between the pilot passages 72 and 73 and the reservoir 130.
4 is provided. The reservoir 130 is connected to a main reservoir (not shown) that supplies brake fluid to the mask cylinder 14.

The directional valve 134 includes a control piston 137 that is substantially liquid-tightly and slidably fitted by a housing 135 and a spring 138 that biases the control piston 137 to the rearward end position shown. The directional control valve 134 is
A first port 144 connected to the first pilot chamber 54 of the flow control device 26 and a second port connected to the reservoir 130
Port 146 and third port 1 connected to liquid passage 22
48, and when the control piston 137 is at the retracted end position, the first port 144 is shut off from the second port 146 and communicated with the third port 148, but it moves to the left in the figure from the retracted end position. When the forward end position is reached, the first port 144 is cut off from the third port 148 and communicated with the second port 146. The first pilot chamber 54 of the flow control device 26 is normally communicated with the wheel cylinder 16, but when the control piston 137 is advanced, it is communicated with the reservoir 130.

The control piston 137 is fitted into the housing 135, so that the first pilot chamber 15 is formed within the housing 135.
0, the second pilot compartment 152 and the third pilot compartment 154
and an atmospheric pressure chamber 156. The first pilot chamber 150 and the third pilot chamber 154 are for introducing a first pilot pressure and a third pilot pressure, respectively, which act on the control piston 137 in the direction of retracting it, and the second pilot chamber 152 is for introducing a second pilot pressure acting on the control piston 137 in a direction to advance it. And the first pilot chamber 150
is the liquid passage 86, the second pilot chamber 152 is the liquid passage 22,
The third pilot chamber 154 is connected to the pump 4 in the pump passage 42.
0 and the check valve 44, the atmospheric pressure chambers 156 are connected to reservoirs 158, respectively.

Note that the left rear wheel system is also provided with a direction switching valve 170 and a reservoir 172 corresponding to the reservoir 130,
The first pilot chamber 150 of the directional control valve 170 is connected to the liquid passage 2.
2. The second pilot chamber 152 is connected to the liquid passage 86, and the third pilot chamber 154 is connected to a portion of the pump passage 102 between the pump 100 and the check valve 106, respectively.

Further, the pump 40, of each of the pump passages 42, 102,
A brake fluid absorber 176 is provided between the brake fluid absorber 100 and the check valves 44 and 106, respectively. The brake fluid absorber 176 includes a piston 182 that is slidably fitted in a substantially fluid-tight manner by a housing 180, and the piston 182 is attached in a direction that reduces the volume of a fluid chamber 184 formed in front of the piston 182. A spring 186 is provided. Brake fluid absorber 176 is directional valve 134170
The brake fluid discharged from the third pilot chamber 154 as the control piston 137 moves forward is stored under pressure in the fluid chamber 184. Note that the volume of the liquid chamber 184 is approximately equal to the volume of the third pilot chamber 154, and
The biasing force of the spring 186 is set to be large enough to overcome the opening pressure of the check valves 44 and 106.

In the recirculation type anti-skid type brake system constructed as described above, the two-position valve 28.90 is always in the pressure increasing position as shown in FIG. In addition, the mask cylinder 14
No hydraulic pressure is generated in the pumps 40, 10.
Since 0 is not activated, the flow control device 26.8
The directional control valve 134,1
70 1st, 2nd. The third pilot pressure is also zero. The flow control device 26.88 is in a state where the flow path area is maximum, and the directional control valves 134, 170 are in a state to communicate the first pilot chamber 54 of the flow control device 26.88 with the wheel cylinder 16.18.

If the brake pedal 1o is depressed in this state,
“Since the second pilot pressure in the flow control device 26,88 is not increased to a height that overcomes the sum of the first pilot pressure and the biasing force of the spring 7°, the control piston 48 is in the retracted end position, Brake fluid is supplied from the mask cylinder 14 to the wheel cylinders 16.18 in large quantities.

In other words, in this state (hereinafter referred to as non-controlled state), as shown in FIG.
The hydraulic pressure in the first pilot chamber 54, the hydraulic pressure in the wheel cylinder 16 for the right rear wheel, and the hydraulic pressure in the wheel cylinder 18 for the left rear wheel are increased so that they are almost equal to each other, while the pump 40
, 100 are set to zero.

Assuming that the current road surface is a straddling road with different friction coefficients on the left and right sides, and that the right rear wheel is in contact with the road surface with a higher friction coefficient, and the left rear wheel is in contact with the road surface with a lower friction coefficient, brake pedal 1
When the pedal effort at 0 is gradually increased, a locking tendency occurs in the left rear wheel, and the control device 34 determines whether the left rear wheel has a locking tendency based on the output signal from the wheel speed sensor 98 or the like. It is assumed that this occurred. Thereafter, the control device 34 starts anti-skid control for the left rear wheel, and specifically first executes a pressure reduction mode in which the two-position valve 90 is continuously switched to the pressure reduction position. The vehicle shifts to a one-sided control state in which anti-skid control is performed only on the left rear wheel.

By executing the decompression mode, a portion of the brake fluid in the wheel cylinder 18 passes through the reservoir passage 92 to the reservoir 94.
is discharged to. As a result, wheel cylinder 1 of the left rear wheel
In other words, the first hydraulic pressure of the directional control valve 134 of the right rear wheel system
The pilot pressure becomes lower than the hydraulic pressure of the wheel cylinder 16 of the right rear wheel, that is, the second pilot pressure. When the second biloft pressure overcomes the sum of the first pilot pressure and the urging force of the spring 138, the control piston 137 moves forward and the first pilot chamber 54 of the flow control device 26 of the right rear wheel system moves forward.
is cut off from the wheel cylinder 16 and communicated with the reservoir 30. As a result, the control piston 4 discharges the brake fluid in the first pilot chamber 54 into the reservoir 130 and moves to the forward end position, thereby minimizing the flow path area. Therefore, during one-sided control, as shown in Figure 2,
The hydraulic pressure in the wheel cylinder 16 of the right rear wheel (high μ side) where anti-skid control is not started is increased at a gradient smaller than the pressure increasing gradient of the fluid pressure in the mask cylinder 14. At this time, the fluid pressure in the first pilot chamber 54 of the flow rate control device 26 is reduced, and the left rear wheel (low μ side) where anti-skid control has started is
The hydraulic pressure in the wheel cylinder 18 is reduced, and the pump 40
The discharge pressure remains at zero. As is clear from the figure, the difference in hydraulic pressure between the left and right rear wheel cylinders 16 and 18 is gentler than when the hydraulic pressure in the right rear wheel cylinder 16 is increased at the same gradient as the hydraulic pressure in the mask cylinder 14.
As a result, a rapid increase in the yaw moment of the vehicle is suppressed, and the straight-line performance of the vehicle is improved.

By executing the decompression mode, the wheel cylinder 1 of the left rear wheel
If the hydraulic pressure at No. 8 decreases, the slip rate of the left rear wheel will recover. The control device 34 determines whether or not the locking tendency of the left rear wheel has tended to be resolved based on the output signal from the wheel speed sensor 98, etc., and if it is determined that the tendency to eliminate the locking tendency has occurred, the control device 34 shifts to the gradual pressure increase mode. do. In the slow pressure increase mode, the hydraulic pressure in the wheel cylinder 18 is changed to the pressure increase position by repeatedly switching the two-position valve 90 between the pressure increase position and the pressure decrease position for a predetermined period of time. In this mode, the pressure increases more slowly than when continuously switching to . Note that when the two-position valve 90 is switched to the pressure increasing position, the fluid pressure in the wheel cylinder 18 increases at a speed corresponding to the difference between the fluid pressure in the wheel cylinder 18 and the fluid pressure in the mask cylinder 14 due to the action of the flow rate control device 88. The amount of pressure increase in the hydraulic pressure of the cylinder 18 becomes approximately constant.

Thereafter, if anti-skid control for the right rear wheel is started while anti-skid control for the left rear wheel is being executed due to the further increase in the depression force on the brake pedal 10, the two-position valve 28 is set to the pressure reducing position. At the same time as the switching command is issued, an operation start command is issued to the pump 40, so the discharge pressure of the pump 40 is increased. In this state (hereinafter referred to as both-side control state), if the sum of the third pilot pressure, the first pilot pressure, and the biasing force of the spring 138 overcomes the second pilot pressure in the direction switching valve 134 of the right rear wheel. , the control piston 137 returns to the rearward end position to communicate the first pilot chamber 54 of the flow rate control device 28 with the wheel cylinder 16. Thereby, from now on, the pressure increase gradient of the wheel cylinder 16 when the two-position valve 28 is in the pressure increase position becomes a magnitude corresponding to the hydraulic pressure difference between the mask cylinder 14 and the wheel cylinder 16.

In other words, during both-side control, as shown in FIG. The hydraulic pressures in the pilot chamber 54 are approximately equal to each other.

If the anti-skid control for each wheel becomes unnecessary after the pressure reduction mode and slow pressure increase mode are repeated many times, 2.
The position valve 28.90 is returned to its normal state in which it is continuously switched to the pressure increase position.

In this case, the first and second pilot pressures of the flow rate control device 26, 88 return to an equal pressure state, and the control piston 48 returns to the rearward end position.

Above, we have explained the case where the right rear wheel touches the high μ side of the straddling road and the left rear wheel touches the low μ side, but the right rear wheel touches the low μ side and the left rear wheel touches the high μ side.
The case of contact with the side is similar to the previous case, so the explanation will be omitted.

As is clear from the above explanation, in this example,
The wheel speed sensor 38, 98□ vehicle speed sensor 39, the control device 34, etc. constitute an anti-skid control device, and the directional control valves 134, 170 . Reservoir 130.158.1'7
2. The brake fluid absorber 176 and the like constitute a pilot type flow rate reduction device.

In addition, in this embodiment, the direction switching valve 134 for the right rear wheel is
The first pilot chamber 150 of the left rear wheel directional control valve 170 is connected to the liquid passage 86, the second pilot chamber 152 is connected to the liquid passage 22, the first pilot chamber 150 of the left rear wheel directional control valve 170 is connected to the liquid passage 22, and the second pilot chamber 152 is connected to the liquid passage 86. However, in the right rear wheel system, the first pilot chamber 150 is a part to which a hydraulic pressure substantially equal to the hydraulic pressure of the left rear wheel wheel cylinder 18 is transmitted; In the case of the right rear wheel system, the second Byrondo chamber 152 is connected to the part to which the hydraulic pressure substantially equal to the hydraulic pressure of the wheel cylinder 16 of the right rear wheel is transmitted. In the case of the left rear wheel system, it is connected to a portion to which a hydraulic pressure substantially equal to the hydraulic pressure of the wheel cylinder 18 of the left rear wheel is transmitted. That's fine. For example, the first pilot chamber 54 of the right rear wheel system may be connected to the pilot throat passage 110 of the left rear wheel system.

In the above embodiment, during one-sided control, the flow rate control device 2
The control piston 4B was moved forward by lowering the hydraulic pressure in the first pilot chamber 54 at 6.88, but the hydraulic pressure in the mask cylinder 14 was applied to each control piston 48 to increase the flow path area. By acting in the decreasing direction, it is also possible to realize the forward movement of the control piston 48 during one-sided control. An example of this is shown in FIG. Please note that this diagram only shows the right rear wheel system.
The following explanation will be given only for the right rear wheel. Further, elements common to the embodiment shown in FIG. 1 are denoted by the same reference numerals to indicate correspondence.

The flow rate control device 220 includes the first. 2nd pilot room 5
4.56, a third pilot chamber 222 and an atmospheric pressure chamber 226 communicating with a reservoir 224 are provided.

A third pilot pressure is applied to the third pilot chamber 222 in a direction that moves the control piston 48 forward. A directional control valve 230 is connected between the third pilot chamber 222, the mask cylinder 14, and the reservoir 228. The directional control valve 230 is connected to the first boat 232. which is connected to the third pilot chamber 222. It has a second boat 234 connected to the reservoir 228 and a third boat 236 connected to the master cylinder 14, and when the control piston 137 is at the rearward end position, which is the original position shown, the first boat 232 is connected to the reservoir 228. It is cut off from the third boat 236 and communicated with the second boat 234, and when it is at the forward end position, it is cut off from the second boat 234 and communicated with the third boat 236. That is, when the control piston 137 is at the backward end position, the third pilot chamber 222 is communicated with the reservoir 228, but when the control piston 137 is at the forward end position, it is communicated with the mask cylinder 14.

Therefore, in the one-sided control state in which anti-skid control is performed for the left rear wheel but not for the right rear wheel, the hydraulic pressure of the mask cylinder 14 is transferred to the third The third pilot pressure is transmitted to the pilot chamber 222, and the control piston 48 moves to the forward end position to minimize the flow area.

In the above embodiment, the hydraulic pressure of the mask cylinder 14 is transmitted to the third pilot chamber 222 during one-sided control, but for example, the hydraulic pressure of the mask cylinder 14 is transmitted to the third pilot chamber 222.
If the hydraulic pressure is , it is sufficient that the hydraulic pressure that increases in response to the brake operation is transmitted.

As is clear from the above explanation, in this example,
The third pilot chamber 222 of the flow rate control device 220. Parts constituting the atmospheric pressure chamber 224 etc. and the third part of the control piston 48
The parts constituting the parts to which pilot pressure and atmospheric pressure are applied, the reservoirs 158, 224, 228, the directional control valve 230, and the brake fluid absorber 176 constitute a pilot-type flow rate reduction device. .

The embodiments of the present invention have been described above in detail based on the drawings, but the directional control valves 134, 170, 230 may be changed from pilot type to electromagnetic type, each 2-position valve 28.90 and each wheel cylinder 16.90. The present invention can be practiced with various modifications and improvements based on the knowledge of those skilled in the art, such as by providing a provisioning valve between the two.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an anti-skid type brake device which is an embodiment of the present invention. FIG. 2 is a graph for explaining the operation of the above embodiment. FIG. 3 is a system diagram of an anti-skid type brake device according to another embodiment. Fourth
Figures 6 to 6 show how to reduce the pressure increase gradient of the wheel cylinder hydraulic pressure of the high-μ side wheel when the brake is applied in a state where the respective coefficients of friction between the left and right wheels and the road surface are greatly different. For example, it is a graph for explaining how the wheel cylinder hydraulic pressure difference between the left and right wheels is suppressed from increasing rapidly. 14: Mask cylinder 16.18: Wheel cylinder 26.88, 220: Flow rate control device 2B, 90: 2 position valve 34: Control device 134.17
0,230: Directional switching valve

Claims (1)

[Scope of Claims] Two electromagnetic valve devices are connected between a hydraulic pressure source and each wheel cylinder of the left and right wheels, and the hydraulic pressure of each of the wheel cylinders is controlled based on the lock tendency of each of the left and right wheels. an anti-skid control device that controls the anti-skid through each solenoid valve device; Normally, brake fluid is allowed to flow from the hydraulic pressure source toward each wheel cylinder at a large flow rate by operating valves that receive pilot pressure in opposite directions, but during anti-skid control, the brake fluid flow rate is In an anti-skid brake system, the anti-skid brake system includes a hydraulic pressure source and two flow rate control devices that reduce the hydraulic pressure difference as the hydraulic pressure difference between each wheel cylinder increases, and each friction coefficient between each of the left and right wheels and the road surface is equal to or greater than a set amount. An anti-skid type brake device characterized in that, in different cases, one of the two flow rate control devices corresponding to the wheel with a higher friction coefficient is provided with a flow rate reduction device for reducing the flow rate of the brake fluid.