JPS5946817B2 - Vehicle brake hydraulic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake hydraulic control device used in vehicles, particularly automobiles.

Conventionally, in automobile braking systems, when braking, the hydraulic pressure of the rear brakes is suppressed from increasing in response to the decrease in the rear wheel load due to the forward movement of the vehicle load, thereby preventing the rear wheels from locking, resulting in efficient braking. In order to achieve this, an impregnation valve is installed in the brake oil path connecting the mask cylinder and the rear brakes, which can reduce the hydraulic pressure generated in the mask cylinder and transmit it to the rear brakes when it senses deceleration of the vehicle exceeding a predetermined value. Interposed brake hydraulic pedestals are known.

By the way, in such a brake hydraulic control device, in order to sense a predetermined deceleration of the vehicle, a weighted valve body that closes in response to the deceleration is installed in a valve chamber formed in the middle of the brake oil passage. There are two problems with this.

One of these is that when the vehicle descends a steep downhill slope, the weight valve malfunctions and prevents the appropriate brake hydraulic pressure from increasing, causing problems in braking operation. Due to the influence of the dynamic pressure of the pressure oil flowing from the cylinder into the valve chamber, the actuation timing of the weight valve element changes depending on the speed of the braking operation, so the increase suppression value of the brake oil pressure changes, and the predetermined brake It is difficult to obtain good performance.

An object of the present invention is to provide the brake hydraulic pressure control device that eliminates such problems.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an overall diagram of a brake hydraulic circuit of an automobile, and a first oil passage is connected to a first output port P1 of a tandem type mask cylinder M operated by a brake pedal. The wheel cylinder of the front wheel brake Bf is connected via L1, and the wheel cylinder of the rear wheel brake Bγ is connected to its second output port P2 via a second oil path L2, and the second oil path L
2, a first control valve v1 and a second control valve V2 are interposed in parallel with each other.

First, to explain the first control valve v1 in detail with reference to FIG. 2, the valve surface 1 faces the front of the vehicle, that is, it is divided into a front case 2 and a rear cover 3, and the cover 3 is The input port 4 is connected upstream of the second oil passage L2, and the box 2 is provided with an output port 5 downstream thereof, and these are integrally connected by bolts 6.

The lid 3 includes a small diameter cylinder hole 7 that communicates with the input port 4, a cylindrical portion 3a that protrudes from the front surface of the lid 3 and defines a damping chamber A inside, and a damping chamber A that extends from the rear of the small diameter cylinder hole 7. On the other hand, the box 2 is provided with a large-diameter cylinder hole 9 that is coaxial with the small-diameter cylinder hole 1 and communicates with the output port 5, and a large-diameter cylinder hole 9 that is sandwiched between it and the small-diameter cylinder hole 7. a cylindrical valve chamber B having an axis extending in the longitudinal direction of the vehicle; and a valve hole 1 opening in the front surface of the valve chamber B.
2, and an outflow passage 13 that communicates the valve hole 12 with the front part of the large diameter cylinder hole 9 is provided.

A small-diameter piston 14 is slid into the small-diameter cylinder hole 7 to define an input hydraulic chamber, and a large-diameter piston 15 is slid into the large-diameter cylinder hole 9 to define an output hydraulic chamber E. .15 are connected to each other in a spring chamber 10, and the spring chamber 10 accommodates a spring 16 that presses the large diameter piston 15 forward, that is, in the direction of the output hydraulic pressure chamber E with a constant spring force.

Although the pistons 14 and 15 are divided into two parts for reasons of machining accuracy, there is no functional problem even if the two parts are integrally formed.

A partition plate 20 is fitted to the open end of the cylindrical portion 3a, and a communication hole 21 formed in the partition plate 20 allows communication between the damping chamber A and the valve chamber 8.

In addition, an elastic valve seat 2 is provided around the valve hole 12 that opens into the valve chamber B.
2, and a spherical weight valve body 23 that cooperates with the valve seat 22 to control opening and closing of the valve hole 12 is accommodated in the valve chamber B.

The bottom surface 24 of the valve chamber B is formed into a slope inclined upwardly at a constant angle θ toward the front of the vehicle by appropriately adjusting the mounting angle of the valve surface 1 to the vehicle body.
It is supported by a partition plate 20 below, and the valve hole 12 is opened.

Thus, when the mask cylinder M is actuated by the brake pedal while the vehicle is running, the signal is delivered from the first output port P1.

The pressure oil is supplied to the front wheel brake Bf through the fourth oil path L1 to operate it, and the pressure oil sent out from the second output port P2 is introduced into the input port 4 through the upstream of the second oil path L2, Pressure oil flows into the damping chamber A from the inflow path 8, is decelerated once in the chamber, and then flows into the valve chamber B through the communication hole. The brake is then supplied to the rear wheel brake Bγ to activate it, and when a predetermined deceleration occurs in the vehicle due to these operations, the weight valve body 23 senses this and climbs the slope 24 by its own inertia force. Seats on the valve seat 22 and closes the valve hole 12 (state shown by chain line)
, the increase in the hydraulic pressure of the rear wheel brake Bγ is suppressed, and the suppression value is large when the loaded weight of the vehicle is heavy, and small when the loaded weight of the vehicle is light.

During normal braking, before the weight valve body 23 operates, the pressure receiving area facing the input hydraulic pressure chamber of the small diameter piston 14 and the pressure receiving area facing the output hydraulic pressure chamber E of the large diameter piston 15 are determined. Due to the difference, the rearward (to the right in the figure) hydraulic pressure force acting on both pistons 14.15 as a whole overcomes the set load of the spring 16, causing both pistons 14.15 to slide rearward.

After that, the increase in the hydraulic pressure of the rear wheel brake Bγ is suppressed by the operation of the weight valve body 23, and then the depression force of the brake pedal is further increased to increase the output hydraulic pressure of the mask cylinder M, and therefore the hydraulic pressure of the input hydraulic pressure chamber. As a result, both pistons 14 and 15 move forward toward their original positions, and the oil pressure in the output oil pressure chamber E, and therefore the working oil pressure of the rear wheel brake Bγ, is increased until the piston 15 comes into contact with the end face of the large diameter cylinder hole 9. It can be raised again.

As a result, after the vehicle decelerates above a certain value, the output hydraulic pressure of the mask cylinder M can be proportionally reduced and transmitted to the rear wheel brake Bγ, reducing the rear wheel load due to the braking effect. This also prevents the rear wheels from locking up.

However, when the vehicle descends a steep slope, the front of the vehicle body tilts toward the front, so the valve surface 1, which normally has a front-closed position, approaches a horizontal state, and the bottom surface 24 of the valve chamber B approaches the horizontal state.
The inclination angle θ becomes approximately zero.

When braking is applied in such a case, the weight valve body 23 closes the valve hole 12 in response to even the slightest deceleration of the vehicle.
Since the hydraulic pressure in the output hydraulic chamber E does not advance the pistons 14 and 15 toward the input port 4 as described above,
After that, even if the output oil pressure of the mask cylinder M is increased,
Correspondingly, only the working oil pressure of the front wheel brake Bf increases, but the working oil pressure of the rear wheel brake Bγ does not increase, resulting in an inconvenience that the braking force of the rear wheel brake Bγ is insufficient.

Such inconvenience may also occur during sudden braking.

That is, when the brake pedal is suddenly depressed, pressure oil that rapidly flows into the valve chamber B from the damping chamber A through the communication hole 21 exerts a high dynamic pressure on the weight valve body 23.
This is because the weight valve body 23 closes the valve hole 12 early before a predetermined deceleration occurs in the vehicle since the weight valve body 23 is pressed toward the second side.

In order to prevent the above-mentioned inconvenience, the present invention connects the second control valve V2 to the second oil passage L2 in parallel with the first control valve (1), and then 2 control valve ■2
will be explained in detail with reference to FIG.

The valve surface 30 has an input port 31 connected to the upstream side of the second oil passage L2 and an output port 32 connected to the downstream side on one side and the other side. The valve seat 33 made of material is divided into an input hydraulic chamber F connected to the input port 31 and an output hydraulic chamber G connected to the output port 32, and cooperates with the valve seat 33 to communicate between the two hydraulic chambers F and G. A shutoff piston-shaped valve body 34 is accommodated within the valve face 30 .

The valve rod 35 of the valve body 34 passes through the valve hole 37 of the valve seat 33 and is slidably supported on both end walls of the valve surface 30. The output hydraulic pressure chamber G is disposed opposite to the output hydraulic pressure chamber G.

The input hydraulic chamber F side part of the valve rod 35 and the output hydraulic chamber G side part of the valve rod 35 have a larger diameter than the pressure receiving surface 36a facing the valve seat 33 of the pressure receiving piston 36. Pressure receiving surface 36b on the opposite side
has a larger area.

A spring 38 that biases this valve body 34 in the direction of the input hydraulic pressure chamber F by a constant spring force is housed in the input hydraulic pressure chamber F, so that the pressure receiving piston 36 normally moves away from the valve seat 33 and opens into the valve hole 37. are doing.

When the mask cylinder M is operated, the pressure oil sent out from the second output port P2 flows through the first and second control valves V1. Divert to the v2 side and input capo)4,
31 and into the input port 4.
The operation of the control valve v1 is as described above.

Now, the pressure oil that has flowed into the input port 31 of the second control valve v2 is supplied to the rear wheel brake Bγ via the input hydraulic chamber F, the valve hole 37, the output hydraulic chamber G, and the output port 32 to operate it.

When the oil pressure in the output oil pressure chamber G reaches a predetermined value due to an increase in the oil pressure generated by the mask cylinder M, the pressure receiving piston 36
In the figure, pressure force due to the rightward hydraulic pressure acting on the pressure receiving piston 36 due to the area difference between the two pressure receiving surfaces 36a and 36b overcomes the set load of the spring 38 and moves the valve body 34 to the right, causing the pressure receiving piston 36 to move. It is engaged with the valve seat 33 to close the valve hole 37 and cut off between the two hydraulic chambers F and G.

After that, if the hydraulic pressure generated by the mask cylinder M is further increased, the hydraulic pressure of the input hydraulic pressure chamber F acting on the pressure receiving surface 36a of the pressure receiving piston 36 will increase, pushing the valve body 34 back to the left and opening the valve hole 37 again. , the pressure in the output hydraulic chamber G also rises, but the rightward pressing force generated due to the area difference between the pressure receiving surfaces 36a and 36b of the pressure receiving piston 36 immediately increases, causing the valve body 34 to move to the right again, causing the valve to close. After closing the hole 37,
Similar operations are repeated as the hydraulic pressure generated by the mask cylinder M increases.

As a result, once the valve body 34 is activated, the hydraulic pressure generated by the mask cylinder M, that is, the hydraulic pressure in the input hydraulic chamber F can be proportionally reduced and transmitted to the output hydraulic chamber G.

Since the second control valve 2 operates in this manner, as mentioned above, the weight valve body 23 may operate early and close the valve hole 12 in the first control valve v1 for some reason. Even if there is, the hydraulic pressure generated by the mask cylinder M can be transmitted to the rear wheel brake Bγ through the second control valve v2.

Therefore, the hydraulic pressure of the rear wheel brake Bγ in this case depends on the characteristics of the second control valve V2.

In addition, at the beginning of the braking operation, the pressure oil from the mask cylinder M is supplied to both control valves v1. Since the flow is diverted to V2, the first control valve V
The amount of oil passing through the first valve chamber B is significantly reduced compared to the conventional device that includes only the first control valve V1.
Since the influence of the dynamic pressure of the pressure oil passing through the weight valve body 23 is reduced, even during sudden braking, the weight valve body 23 maintains the predetermined deceleration of the vehicle without being affected by the dynamic pressure. Able to respond accurately.

Note that the flow rate of the pressure oil in the first control valve V1 can be adjusted as appropriate by narrowing the communication hole 21 and the valve hole 12.

Next, when the brake is released, even though the valve body 34 of the second control valve 2 closes the valve hole 37 due to the rightward pressing force, the pressure oil supplied to the rear wheel brake Bγ 1
Via the output port 5 of the control valve V1, the valve hole 12 (the weight valve body 23 opens this valve hole 12 at the same time as the brake is released), the valve chamber B, the communication hole 21, the damping chamber A, and the input port 4. Since the flow returns to the mask cylinder M, the pressure in the output hydraulic pressure chamber G of the second control valve v2 decreases, and the rightward pressing force against the valve body 34 decreases or disappears. It is possible to return to the position and open the valve hole 37.

Therefore, it is not necessary to provide a special means for returning pressure oil to the second control valve v2.

In the present invention, the second control valve v2 can also be configured as a so-called oil pressure limiting valve that closes when the working oil pressure of the rear wheel brake Bγ rises above a certain value.

In this case, during braking, before the second control valve (2), that is, the hydraulic limit valve, closes, the output hydraulic pressure of the hydraulic limit valve causes the piston 14,15 of the first control valve V1 to resist the set load of the spring 16. The rear control valve ■1. If v2 are both closed, the hydraulic pressure generated in the mask cylinder M is proportionally reduced by the advancement of the piston 14, 15 and transmitted to the rear wheel brake Bγ, and there is no problem.

As described above, according to the present invention, the first control valve is capable of detecting deceleration of the vehicle equal to or higher than a predetermined value, reduces the pressure generated in the mask cylinder, and transmits the reduced pressure to the wheel brakes, and the first control valve is configured to control the working pressure of the wheel brakes to a predetermined value. A second leg valve is installed in the brake oil passage in parallel with a second leg valve that can sense when the oil pressure rises above the specified value and close it, or reduce the pressure generated by the mask cylinder and transmit it to the wheel brakes. During braking, even if the first control valve operates early for some reason before the hydraulic pressure of the wheel brakes has increased to the appropriate value, the hydraulic pressure generated by the mask cylinder is transferred to the wheels through the second control valve, which is still open. It can compensate for the lack of braking force by transmitting it to the brake, achieving an effect that does not interfere with braking.

Also, during normal braking, the influence of the dynamic pressure of the pressure oil on the first control valve is reduced by dividing the pressure oil from the mask cylinder into the first control valve side and the second control valve side and supplying it to the wheel brakes. As a result, the first control valve can accurately respond to the predetermined deceleration of the vehicle, and can appropriately change the starting point for suppressing the increase in the hydraulic pressure of the wheel brakes according to the loaded weight of the vehicle, increasing efficiency. It also achieves the effect that good braking action can be obtained.

[Brief explanation of the drawing]

Fig. 1 shows the brake hydraulic circuit of an automobile equipped with the device of the present invention, and Figs. 2 and 3 show the first and second hydraulic circuit diagrams thereof.
FIG. 3 is a vertical sectional side view of a control valve. Bγ・・・Rear wheel brake as a wheel brake,
L2...Second oil path as hydraulic pressure, M...
・Master cylinder, Vl...1st control valve, ■2
...Second control valve.

Claims (1)

[Claims] 1 A first control valve is installed in the oil path connecting the master cylinder and the wheel brakes, which can reduce the hydraulic pressure generated in the mask cylinder and transmit it to the wheel brakes when deceleration of the vehicle equal to or higher than a predetermined value is detected. A second control valve is arranged in parallel with the first control valve, and is capable of closing when the working pressure of the wheel brake increases to a predetermined value or more, or reducing the pressure of the hydraulic pressure generated in the mask cylinder and transmitting the reduced pressure to the wheel brake. A vehicle brake hydraulic control device that is connected to an oil path.