JPS5953261A - Brake oil pressure controller for car - Google Patents

Abstract

PURPOSE:To obtain brake operation which is approximate to ideal brake operation by transferring the bent point of the brake power distribution by a reducing valve which is installed in an oil passage which connects the output port of a master cylinder and a rear-wheel brake, by utilizing an air spring fitted onto a suspension apparatus. CONSTITUTION:When a brake pedal 1 is stepped-in during the time when a car travels, the pressurized oil generated from the output port P2 of a master cylinder M is supplied into right and left rear-wheel brake Br through the reducing valve 6 of a controller V and an oil passage L3, and brake operation is performed. In this case, said reducing valve 6 is equipped with a pressure receiving piston 7 which is urged rightward by the coil springs 16 and 17 which determine each decompression action starting pressure in the case when a car is loaded or unloaded and a valve piece 11 which opens and closes the communication to an output oil pressure chamber 9 which communicates to an input oil pressure chamber 8 in the piston 7 and an outlet 5. Said valve piece 11 is opened and closed by a control piston 21 which is operated by the pressure in a pressure chamber 24 which communicates to the air chamber 28 of the air spring 27 of an air spring type car height adjuster 25, and thus the bent point can be transferred.

Description

[Detailed description of the invention] The present invention is applicable to vehicles, especially four-wheeled vehicles.

The present invention relates to a brake hydraulic pressure control device that automatically adjusts the working hydraulic pressure of the rear wheel brake according to the required braking force when the rear wheel brake hydraulic circuit is configured into two mutually independent systems.

Conventionally, as this type of control device, a pressure reducing valve that can proportionally reduce and transmit the output hydraulic pressure of the mask cylinder to the rear wheel brake is provided in the oil passage connecting the output port of the mask cylinder and the rear wheel brake. In some cases, the oil passage is equipped with a weight valve that shuts off the oil passage when deceleration exceeding a set value of the vehicle is detected, but in the former case, the bending point in the braking force distribution curve is constant. Therefore, it is not suitable for vehicles such as trucks, where the weight of the vehicle and the load distribution between the front and rear wheels change significantly depending on whether it is empty or loaded, and even in the latter case, it cannot adequately respond to changes in the loaded weight. The problem is that it can't be done.

The present invention was proposed in view of the above-mentioned conventional problems.
It is an object of the present invention to provide the above-mentioned device, which uses an air spring used in a suspension system to displace a bending point of a pressure reducing valve according to a change in the loaded weight of a vehicle, thereby making braking approximate to ideal braking. purpose.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, M indicates a known tandem type mask cylinder operated by a brake pedal 1, Bf indicates left and right front wheel brakes, and Br indicates left and right rear wheel brakes, respectively.

The first output port P1 of the mask cylinder M is connected to the left and right front wheel brakes Bf via the oil passage L1, and the second
The output capo P2 is connected to the rear wheel brake Br via an oil passage L2, a control device V of the present invention, and an oil passage L3.

An inlet 3 connected to the oil path L2 and an outlet 5 connected to the oil path L3 are opened on the outside of the valve surface 2 of the control device V, and a pressure reducing valve 6 for controlling communication between the inlet 3 and the outlet 5 is opened on the valve surface. It is located within 2.

The pressure reducing valve 6 includes a pressure receiving piston 7 slidably housed in the valve surface 2, an input hydraulic chamber 8 formed on the negative side thereof and communicating with the inlet 3, and an input hydraulic chamber 8 formed on the other side of the pressure receiving piston 7. It has an output hydraulic chamber 9 that communicates with the outlet 5, and a spherical valve body 11 that is provided in the input hydraulic chamber 8 and opens and closes a communicating oil passage 10 between both chambers 8 and 9.

Reference numeral 14 indicates a valve seat that cooperates with the valve body 11. A pressure receiving piston 7 which also serves as a valve cover is attached to the valve surface 2 from the side thereof.
One guide shaft member 12 is fitted, and its tip is inserted into the pressure receiving piston 7 in an oil-tight manner to form a fixed wall of the input hydraulic chamber 8. A valve spring 13 is interposed between the end face of the member 12 and the valve body 11 to bias the valve body 11 in the closing direction.

The pressure receiving surface A of the input hydraulic chamber 8 of the pressure receiving piston 7 has a smaller area than the pressure receiving surface B of the output hydraulic chamber 9 (i.e., A
,(B).

Further, the valve face 2 has a spring chamber 15 penetrated by the guide shaft member 12 on one end side, on the left side in the figure, and inside the spring chamber 15, a lid portion 12a of the guide shaft member 12 and a pressure receiving piston 7 are provided.
a first coil spring 16 located between the two and determining the pressure at which the pressure reducing action of the pressure reducing valve 6 starts when the car is empty; and a second coil spring 16 which cooperates with the first coil spring 16 to determine the pressure at which the pressure reducing action starts when the car is loaded. Coil springs 17 are provided double-layered inside and outside. One end of the first coil spring 16 is always in contact with the end surface of the pressure receiving piston 7 via the seat plate 18, and one end of the second coil spring 17 is in contact with the inner surface of the valve surface 2 via the seat plate 19, and the seat plate 19 is configured to be pushed leftward by the pressure receiving piston 7 when the pressure receiving piston 7 slides to the left in the figure by a distance of 81 or more.

Furthermore, a cylinder 20 is attached to the other end of the valve surface 2, on the right side in the figure, and a control piston 2 is installed in the cylinder 20.
1 is slidably mounted, and a pressure chamber 24 is defined between the control piston 21 and the inner surface of the end wall of the cylinder 20.

A long shaft portion 22 consisting of a small diameter portion 22a and a large diameter portion 22b protrudes from the left end surface of the control piston 21.
The tip of the small diameter portion 22 a passes through the partition wall 23 of the valve surface 2 and the communication oil passage 10 of the pressure receiving piston 7 and comes into contact with the valve body 11 . They are separated by S1, and the communication oil passage 10 is opened. The distance S2 between the stepped portion 22e of the shaft portion 22 and the partition wall 23 is the range of the operating stroke of the control piston 21. A return spring 26 for the piston 21 is interposed between the partition wall 23 and the control piston 21.

An air chamber 28 of an air spring 27, which is a component of an air spring 25 of the suspension system, is connected to the pressure chamber 24 of the 6-cylinder 20. The vehicle height adjustment mechanism 25 includes an air compressor 29, a pressure storage tank 30 for storing compressed air, an air spring 27, and a pressure storage tank 30 that introduces compressed air into the air chamber 28 of the air spring 27, and then discharges the compressed air. control valve 3
1 and a coil spring 32. The coil spring 32 is designed to take full responsibility only for the empty vehicle type, and the air spring 27 takes up the entire load for the loaded type. That is, compressed air regulated by the control valve 31 according to the loaded weight is introduced into the air chamber 28 of the air spring 27, thereby keeping the vehicle height constant. Therefore, if the loaded weight is heavy, the air inside the air chamber 2B is If the pressure is high and the loaded weight is light, the pressure inside the air chamber 28 will be low.

Air splashes 2 into the pressure chamber 24 of the cylinder 20 except when the car is empty.
The same pressure as in the air chamber 28 of No. 7, that is, a pressure corresponding to the loaded weight, is introduced, and this causes the control piston 21 to slide a predetermined distance to the left, separating the valve body 11 from the valve seat 14, and creating a space between them. There is a distance depending on the loaded weight. 3
Reference numeral 3 designates an orifice formed in the end wall of the cylinder 20, which completely attenuates when the pressure on the air spring 27 side fluctuates, thereby preventing sudden fluctuations in the pressure within the pressure chamber 24 of the cylinder 20.

Next, the operation of this embodiment will be explained.

While the vehicle is running, depressing the brake pedal 1 activates the mask cylinder M'5, and the first and second output capos Pl,
When hydraulic pressure is output from P2, the output hydraulic pressure from the first output port P1 is transmitted to the left and right front wheel brakes Bf via the oil path L1, and operates them. Further, the output oil pressure of the second output port P2 is transmitted to the left and right rear wheel brakes Br via the oil path L2, the pressure reducing valve 6, and the oil path L3-i, and operates them.

When the output oil pressure of the second output port P2 of the mask cylinder M increases to a predetermined value or more, the pressure reducing valve 6 starts to control the working oil pressure of the rear wheel brake Br.

The action of the hydraulic pressure control X1 differs when the vehicle is empty and when the vehicle is loaded, so they will be explained separately below with reference to FIG. 2 as well.

(a) Hydraulic pressure control when the vehicle is empty [Figure 2 (I)
Reference] When the vehicle is empty, the first coil spring 16 determines the pressure at which the pressure reducing valve 6 starts reducing the pressure, as described above.

Furthermore, when the vehicle is empty, the air chamber 28 of the air spring 27 is under atmospheric pressure, so the pressure chamber 24 of the cylinder 20 is also at the same pressure, and the control piston 21 slides to the right in the figure due to the elastic force of the return spring 26. The distance S1 between the valve body 11 and the valve seat 14, which abut against the inner surface of the end wall of the cylinder 20, remains constant until the pressure receiving piston 7 moves to the left.

In this state, when the hydraulic pressure in the human hydraulic pressure chamber 8 reaches a predetermined value due to the increase in the output hydraulic pressure of the 29th output port (P2) of the mask cylinder M, both pressure receiving surfaces A and B of the human output hydraulic chamber 8. Due to the above-mentioned area difference, the hydraulic pressure applied to the pressure receiving piston 7 to the left in the figure overcomes the set load of the first coil spring 16, causing the pressure receiving piston 7 to slide to the left in the figure by a distance S1. The valve seat 14 is engaged with the valve body 11 to close the oil passage 10 between the person and the output hydraulic chambers 8 and 9 (point Y1 in FIG. 2). After that, if the output oil pressure of the second output port P2 further increases, the oil pressure of the manual hydraulic pressure chamber 8 also increases, so the pressure receiving piston 7 is pushed back to the right in the figure by the oil pressure, and the valve seat 14 is moved away from the valve body 11. They are separated and the communication oil passage 10 is opened to increase the pressure in the output hydraulic chamber 9, but as the pressure increases, the leftward pressing force due to the hydraulic pressure due to the area difference between the pressure receiving surfaces A and B of the pressure receiving piston 7 immediately increases. Then slide the pressure receiving piston 7 again to the left in the figure to engage the valve seat 14 with the valve body 11.
- After that, the same operation is repeated as the output oil pressure of the second output port P2 increases. As a result, the pressure receiving piston 7
Once activated, the hydraulic pressure in the input hydraulic chamber 8 can be proportionally reduced and transmitted to the output hydraulic chamber 9 and therefore to the rear wheel brake Br.

(b) Hydraulic pressure control during loading [Fig. 2 (II)
)] At the time of loading, the first. The pressure at which the pressure reducing valve 6 starts to reduce the pressure is determined by the cooperation of the second coil springs 16 and 17.

When the vehicle is loaded, compressed air corresponding to the loaded weight regulated by the control valve 31 is introduced into the air chamber 28 of the air splash 27. Therefore, the pressure chamber 24 of the cylinder 20 has the same pressure as the air chamber 28, and the control piston 21 slides a predetermined distance to the left in the figure, returning the elastic force of the spring 26 and the pressing force applied to the pressure chamber 240 and the control piston 21. stops at a balanced position, and as a result, a longer distance is formed between the valve body 11 and the valve seat 14 than when the vehicle is empty, so that the timing of closing the valve body 11 is later than when the vehicle is empty.

Although the moving distance of the valve body 11 depends on the loaded weight of the vehicle, the maximum moving distance is limited to the maximum operating stroke s2 of the control piston 21 regulated by the shaft portion 22.

For convenience, let us assume that the control piston 21 has moved by the maximum operating stroke S2, and the valve body 11 has moved from the valve seat 14 to S 1-i-
It is located at a distance of S2.

In this state, the second output capo of the mask cylinder M
The output oil pressure of P2 is sent to the rear wheel brake Br via the communication oil path 10.
The braking force increases in a one-to-one relationship with the braking force acting on the front wheel brake Bf. On the other hand, a leftward pressing force in the figure due to the hydraulic pressure caused by the area difference between the pressure receiving surfaces A and B of the output hydraulic chambers 8 and 9 acts on the pressure receiving piston 7, and the pressure receiving piston 7 is moved by the set load of the first coil spring 16. The end face of the second coil spring 1γ is still brought into contact with the seat plate 19 of the second coil spring 1γ. In this state, the valve body 11 has not yet closed the communicating oil passage 10, so the braking force acting on the rear wheel brake Br continues to increase as described above.

When the output oil pressure of the second output port P2 further increases and the oil pressure of the input oil pressure chamber 8 reaches a predetermined value, the leftward pressing force in the figure due to the oil pressure acting on the pressure receiving piston 7 as described above is applied to the first and second coils. Overcoming the set load of the springs 16 and 11, the pressure receiving piston 7 is slid to the left in the figure by a distance S2, and at this point the valve seat 14 is finally engaged with the valve body 11, and the output hydraulic pressure chamber 8. Close the communication oil passage 10 between 9 (Y2 point in Figure 2)
, the same operation as in (a) above is repeated, and the hydraulic pressure in the manual hydraulic chamber 8 is proportionally reduced and transmitted to the rear wheel brake Br, and thus the pressure reducing action of the pressure reducing valve 6 starts 13- The pressure reaches its maximum. Automatically adjusted.

As described above, according to the present invention, the pressure reducing valve is provided in the oil passage connecting between the output port of the mask cylinder and the rear wheel brake, and is capable of proportionally reducing and transmitting the output hydraulic pressure of the output port to the rear wheel brake. The pressure-reducing valve is equipped with a spring that determines the pressure at which the pressure-reducing action starts, and a control piston that normally holds the pressure-reducing valve in an open state is slid into the cylinder attached to the pressure-reducing valve. A pressure chamber is defined between the control piston and the inner surface of the cylinder end wall, and an air spring of a suspension device is installed in the pressure chamber so that the control piston can delay the closing timing of the pressure reducing valve as the loaded weight of the vehicle increases. Since these are connected, the pressure at which the pressure reducing valve starts reducing the pressure can be automatically increased in accordance with the above increase, and the braking can be approximated to the ideal braking. Furthermore, the structure is simple and the entire device can be made compact, and there is also the advantage that there are no restrictions on the mounting position of the device or the mounting angle as in the case of G-pulp.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view of an embodiment of the present invention, and FIG. 2 is a graph showing braking force distribution between front and rear wheels. Br...Rear brake, L2. L3... oil path, M...
・Mask cylinder, P2... 2nd output port, ■...
-Control device, 6...pressure reducing valve, γ...pressure receiving piston/. 16... First coil spring, 17... Second coil spring, 20... Cylinder, 21... Control piston, 24
...Pressure chamber, 27...Air splash patent applicant Nissin Kogyo Co., Ltd. 15-

Claims (1)

[Claims] A pressure reducing valve capable of proportionally reducing and transmitting the output hydraulic pressure of the output port to the rear wheel brake is interposed in the oil passage connecting between the output port of the mask cylinder and the rear wheel brake,
The pressure reducing valve is provided with a spring that determines the pressure at which its pressure reducing action starts, and a control piston that normally holds the pressure reducing valve in an open state is slid into a cylinder attached to the pressure reducing valve. A pressure chamber is defined between the inner surface of the cylinder end wall, and air from a suspension system is supplied to the pressure chamber so that the control piston can delay the closing timing of the pressure reducing valve in accordance with an increase in the loaded weight of the vehicle. A vehicle brake hydraulic control device that connects springs.