JPH0220463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake hydraulic control device in a vehicle, and particularly to a brake hydraulic control device that is installed in an oil passage connecting a first output port of a master cylinder and one rear wheel brake. A first pressure reducing valve capable of proportionally reducing and transmitting the output hydraulic pressure of the port to the one rear wheel brake, and an oil passage connecting between the second output port of the master cylinder and the other rear wheel brake. and a second pressure reducing valve capable of proportionally reducing and transmitting the output hydraulic pressure of the second output port to the other rear wheel brake are arranged in parallel in a common valve case. It is something.

A device of the type described above is conventionally known in which the braking force of the rear wheels is independently controlled to prevent the rear wheels from locking due to a reduction in the rear wheel load due to braking. When braking a vehicle using such a conventional device, in order to make the braking approximate to ideal braking, the pressure at which the pressure reducing valve starts its pressure reducing action must be changed according to the loaded weight of the vehicle. It is necessary to make the depressurization start pressure higher than that when the car is empty.

Therefore, by applying the pressure of the air spring of the suspension system to the valve body of the pressure reducing valve on the valve opening side, the pressure reducing action start pressure of the pressure reducing valve can be changed in accordance with the loaded weight of the vehicle. Means for changing the start pressure has already been proposed, but since two pressure reducing valves are provided in the above-mentioned type of device, it is necessary to separately provide the above-mentioned pressure reducing action start changing means for each of them, which increases the cost as a whole. There was a problem.

The present invention has been proposed in view of the above, and can solve all of the above problems of conventional devices.
Moreover, it is an object of the present invention to provide a brake hydraulic control device for a vehicle that has fewer malfunctions.

In order to achieve this object, the present invention provides an oil passage that connects the first output port of the master cylinder and one of the rear wheel brakes.
A first pressure reducing valve capable of proportionally reducing and transmitting the output hydraulic pressure of the output port to the one rear wheel brake, and an oil path connecting between the second output port of the master cylinder and the other rear wheel brake. A second pressure reducing valve that is interposed therein and is capable of proportionally reducing and transmitting the output hydraulic pressure of the second output port to the other rear wheel brake is arranged in parallel in a common valve box. In the brake hydraulic control device, the valve box includes the first and second valves.
A balance lever having both ends bridged is housed between the valve bodies of the pressure reducing valve, and a piston having a fulcrum part that swingably supports the balance lever at its center position is slidably fitted, and the piston and an end wall of the valve case, and the pressure chamber is configured such that the piston can delay the closing timing of the pressure reducing valve via a balance lever in response to an increase in the load of the vehicle. The air chamber of the air spring of the suspension system is communicated with the air chamber, and an orifice is interposed in the communication path.

Hereinafter, an embodiment in which the device of the present invention is configured for a two-system brake system will be described with reference to the drawings. First, in _{FIG .} are left and right front wheel brakes, Br ₁ ,
Br ₂ indicates the left and right rear wheel brakes, respectively. Reference numeral 2 denotes a valve box (not shown) that is fixed to a proper position on the vehicle body, and on the outside thereof, the first and second output ports P ₁ and P ₂ of the master cylinder M are connected via oil passages L ₁ and L ₂ , respectively. _The left _{and right rear} wheel brakes Br ₁ ,
First and second outlets 4 each connected to Br _2
1 and 4 ₂ are open, and there is communication between the first inlet 3 ₁ and _{the first outlet 4 1 and the second inlet 3 2 and} the second outlet 4 _{2 .}
First and second pressure reducing valves 5 ₁ and 5 ₂ are provided in parallel within the valve box 2 to respectively control communication between them.
The left and right front wheel brakes Bf ₁ and Bf ₂ are connected to oil passages L ₂ f and L ₁ f that branch from oil passages L ₂ and L ₁ .

The first pressure reducing valve 5 ₁ is made of an input hydraulic chamber 6 and an output hydraulic chamber 7 that communicate with the first inlet 3 ₁ and the first outlet 4 ₁ , respectively, and a rubber or the like installed between the two hydraulic chambers 6 and 7. It is composed of an elastic valve seat 8 and a valve body 9 that cooperates with the valve seat 8 to communicate and cut off communication between the two hydraulic chambers 6 and 7. The valve body 9 is provided at the tip of a valve rod 9a that passes through the valve hole of the valve seat 8 and the input hydraulic pressure chamber 6.
A piston-like valve portion 9b that cooperates with the valve seat 8 and a guide shaft 9c that protrudes from its outer end surface are integrally formed. is slidably supported via the seal member 11, and the valve portion 9b and the protruding shaft 9
c is arranged in the output hydraulic chamber 7, and the protruding shaft 9c is loosely fitted into the small diameter hole 12 of the output hydraulic chamber 7. A coil spring 13 that holds the valve seat 8 and the seal member 11 is compressed between the valve seat 8 and the seal member 11 .

The second pressure reducing valve 5 ₂ has the same configuration as the first pressure reducing valve 5 ₁ except that the input and output hydraulic chambers 6 and 7 are communicated with the second inlet 3 ₂ and the second outlet 4 ₂ , respectively. ,
In this figure, parts corresponding to the first pressure reducing valve ₅₁ are given the same reference numerals.

Further, the valve box 2 includes first and second pressure reducing valves 5 ₁ ,
A housing ₁₆ is fixed with bolts 17, and has a large-diameter lever accommodating portion 14 adjacent to the input hydraulic chambers 6, 6, and a small-diameter cylinder portion 15 communicating with the lever accommodating portion 14 and located outside the lever accommodating portion 14. A circular balance lever 18 is accommodated within the lever housing portion 14, which bridges between the ends of the two valve rods 9a, _9a of the pressure reducing valves ₅₁ , 52 that protrude into the lever housing portion 14. Further, a piston 19 is slidably fitted within the cylinder portion 15, and a pressure chamber 20 is defined between the outer end surface of the piston 19 and the inner wall surface of the cylinder portion 15. A hemispherical protrusion 19a as a fulcrum that swingably supports the center of the balance lever 18 is protruded from the center of the tip surface of the piston 19; It faces the concave surface 18a.

An air chamber 23 of an air spring 22 that is a component of an air spring type vehicle height adjustment mechanism 21 of the suspension system is connected to the pressure chamber 20 . The vehicle height adjustment mechanism 21 includes an air compressor 24 and a pressure storage tank 2 that stores compressed air.
5, an air spring 22, a control valve 26 capable of introducing compressed air from an accumulator tank 25 into the air chamber 23 of the air spring 22, and discharging it from the air chamber 23, and a coil spring 2.
7. The coil spring 27 is designed to bear only the weight of the empty vehicle, and the air spring 22 bears the weight of the loaded vehicle. That is, compressed air regulated by the control valve 26 according to the loaded weight is supplied to the air spring 22.
This is to keep the vehicle height constant. Therefore, if the loaded weight is heavy, the pressure in the air chamber 23 will be high, and if the loaded weight is light, the pressure in the air chamber 23 will be low. .

The same pressure as the air chamber 23 of the air spring 22, that is, the pressure corresponding to the loaded weight, is introduced into the pressure chamber 20 of the cylinder part 15 except when the vehicle is empty, and this causes the piston 19 to slide to the left in the figure. , which causes both valve bodies 9,9 to slide in the same direction via the balance lever 18, so that each valve part 9b of both valve bodies 9,9 is aligned with the valve seat 8.
Each is held at a separate position from the other. Reference numeral 28 denotes an orifice formed on the outer end wall of the cylinder section 15, which attenuates pulsations in the pressure on the air spring 22 side and prevents sudden fluctuations in the pressure within the pressure chamber 20 of the cylinder section 15. It is.

Next, the operation of this embodiment will be explained. While the vehicle is running, the brake pedal 1 is depressed to operate the master cylinder M, and the first and second output ports P ₁ ,
If hydraulic pressure is output from P ₂ , the first output port P ₁
The output oil pressure is sent to the right front wheel brake through oil passages L ₁ and L ₁ f.
Bf ₂ and from the input hydraulic chamber 6 of the first pressure reducing valve 5 ₁ to the left rear wheel brake Br ₁ via the output hydraulic chamber 7 communicating therewith and the oil passage L ₁ r to operate them. On the other hand, the output hydraulic pressure of the second output port P ₂ is transmitted to the left front wheel brake Bf ₁ via oil paths L ₂ and L ₂ f, and from the input hydraulic chamber 6 of the second pressure reducing valve 5 ₂ to the output hydraulic chamber 7 communicating therewith. The oil is transmitted to the right rear wheel brake Br ₂ via the oil path L ₂ r, respectively, to operate them.

When _{the output oil pressures of the first and second output ports P 1 and P 2 of} the master cylinder M rise above a predetermined value, the first and second pressure reducing valves 5 ₁ and 5 ₂ actuate the rear wheel brakes.
This starts controlling the hydraulic pressure of Br ₁ and Br ₂ , respectively, and its operation will be explained in detail next.

First, when the first pressure reducing valve ₅₁ is turned on due to an increase in the output oil pressure of the first output port _P1 , and the oil pressure in the output oil pressure chambers 6 and 7 reaches a predetermined value, the oil pressure acting on the valve body 9 causes a change in the right direction in the diagram. The pressing force (corresponding to the product of the cross-sectional area A of the base of the valve rod 9a and the hydraulic pressure of the output hydraulic chambers 6 and 7) is the pressure introduced into the pressure chamber 20 of the cylinder section 15, that is, the pressure of the air spring 22. Overcoming the biasing force exerted on the valve body 9 by the air chamber pressure, the valve body 9 is moved to the right in the figure, and the valve portion 9b is seated on the valve seat 8 and closed, cutting off communication between the output hydraulic chambers 6 and 7. do. After that, when the output oil pressure of the first output port _P1 further increases, the leftward pressing force of the valve body 9 due to the oil pressure of the input oil pressure chamber 6 (the cross-sectional area B of the valve portion 9b and the cross-sectional area A
This approximately corresponds to the difference between the two times multiplied by the oil pressure in the input oil pressure chamber 6. ) is the valve body 9 due to the hydraulic pressure of the output hydraulic chamber 7.
rightward pressing force (output hydraulic chamber 7 in the cross-sectional area B)
It is approximately equivalent to the oil pressure multiplied by . ), the valve body 9 is pushed back to the left, the valve part 9b is separated from the valve seat 8, and the two hydraulic chambers 6 and 7 are communicated again, so the pressure in the output hydraulic chamber 7 is increased. The rightward pressing force of the valve body 9 due to the hydraulic pressure of the output hydraulic chamber 7 immediately increases, and the valve body 9 is moved to the right again to cut off the communication between the two hydraulic chambers 6 and 7, and from then on, the first output port
Similar operations are repeated as the output oil pressure of P ₁ increases, and as a result, the output oil pressure of the first output port P ₁ can be proportionally reduced and transmitted to the left rear wheel brake Br ₁ .

In this case, the pressure at which the pressure reducing valve ₅₁ starts reducing pressure is determined by the cross-sectional area A and the air chamber pressure of the air spring 22, and the air chamber pressure changes depending on the loaded weight of the vehicle, so the braking is approximated to ideal braking. can be done. Further, the pressure reduction ratio is approximately determined by the ratio between the cross-sectional area (B-A) and the cross-sectional area A.

On the other hand, if the output oil pressure of the second output port _P2 rises above a predetermined value, the second pressure reducing valve ₅₂ operates in the same way as the first pressure reducing valve ₅₁ , and the output oil pressure is transferred to the right rear wheel brake _Br2. The pressure is proportionally reduced and transmitted.

By the way, when both the pressure reducing valves 5 ₁ and 5 ₂ are operated, there is generally a slight error in the operating timing and operating stroke of each valve body 9, 9, and the balance lever 13 is adjusted to the hemispherical shape of the piston 19 according to these errors. Protrusion 19
By tilting around a as a fulcrum, the pressure in the pressure chamber 20 of the cylinder section 15 can always be equally distributed to both valve bodies 9, 9, and as a result, the pressure at which the pressure reducing action of both pressure reducing valves ₅₁ , ₅₂ starts is ensured. balance.

As described above, according to the present invention, the oil passage connecting the first output port of the master cylinder and one of the rear wheel brakes is interposed, and the output hydraulic pressure of the first output port is transferred to the rear wheel brake. a first pressure reducing valve capable of proportionally reducing and transmitting pressure to the wheel brake; and a second output port interposed in an oil passage connecting between the second output port of the master cylinder and the other rear wheel brake. A brake hydraulic control device for a vehicle, comprising a second pressure reducing valve capable of proportionally reducing the output hydraulic pressure of the other rear wheel brake and transmitting the pressure to the other rear wheel brake. A sliding piston accommodates a balance lever whose both ends are bridged between the valve bodies of the first and second pressure reducing valves, and has a fulcrum part that swingably supports the balance lever at its center position. such that the piston and the end wall of the valve housing are able to fit together to define a pressure chamber between the piston and the end wall of the valve housing, and the piston closes the pressure reducing valve via a balance lever in response to an increase in the payload of the vehicle. In order to delay the timing, the air chamber of the air spring of the suspension system is communicated with the pressure chamber, so that the pressure at which the pressure reducing action of the pressure reducing valve starts is adjusted to the increase in pressure in the air chamber of the air spring, that is, the increase in the loaded weight of the vehicle. The load can be automatically increased accordingly, and braking can always be performed accurately depending on the size of the loaded weight. Moreover, there are no major restrictions on the mounting position or angle of the valve case as in conventional devices that use a G valve to operate the piston, and the piston does not malfunction due to the tilt of the vehicle such as when driving on a slope. No doubt. In addition, even if there is a slight deviation in the operating timing or operating stroke of each valve body when the first and second pressure reducing valves installed in parallel in the valve case are operated, the balance lever is moved around the above-mentioned fulcrum of the piston according to the deviation. Since the air pressure in the pressure chamber can always be evenly distributed to both valve bodies by tilting the pressure chamber effortlessly, the pressure at which the pressure reducing action of both pressure reducing valves starts can always be the same, and the braking characteristics of the left and right rear wheels can be made equal. can do. Furthermore, since the balance lever and the piston are housed in a common valve case together with both pressure reducing valves and protected by the valve case, they can contribute to improving their durability.

In particular, an orifice is installed in the communication path between the air chamber of the air spring and the pressure chamber, so even if the pressure in the air chamber momentarily increases or decreases due to unevenness on the road surface, the pressure in the orifice will remain constant. The damping effect can suppress sudden pressure fluctuations in the pressure chamber, effectively preventing the piston from malfunctioning due to pressure fluctuations, and therefore prevents the piston from malfunctioning even when the vehicle is tilted as described above. Coupled with the effect of preventing this from happening, it can greatly contribute to improving the operating accuracy of the piston.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. Br ₁ , Br ₂ ... Left and right rear wheel brakes, L ₁ , L ₂ ,
L ₁ f, L ₁ r, L ₂ f, L ₂ r...oil path, M...master cylinder, P ₁ , P ₂ ...first and second output ports, 5 ₁ ,
5 ₂ ...First and second pressure reducing valves, 9...Valve body, 18...
...Equilibrium lever, 19...Piston, 19a...Protrusion as a fulcrum, 22...Air spring, 23...
Air chamber, 28...Orifice, _P1 , _P2 ...1st,
Second output port.

Claims (1)

[Claims] 1 An oil passage connecting the first output port P ₁ of the master cylinder M and one rear wheel brake Br ₁ is installed, and the output hydraulic pressure of the first output port P ₁ is connected to the one rear wheel brake. A first pressure reducing valve ₅₁ capable of proportionally reducing pressure to _Br1 and transmitting the pressure is interposed in an oil passage connecting between the second output port _P2 of the master cylinder M and the other rear wheel brake _Br2 . and the second output port
A vehicle brake hydraulic control system in which a second pressure reducing valve ₅₂ capable of proportionally reducing and transmitting the output hydraulic pressure of _P2 to the other rear wheel brake _Br2 is arranged in parallel in a common valve case 2. In the device, a balance lever 18 whose both ends are bridged between the valve bodies 9 of the first and second pressure reducing valves 5 ₁ and 5 ₂ is housed in the valve case 2, and the balance lever 18 is connected to the center of the valve case 2. A piston 19 having a fulcrum portion 19a that is swingably supported in the position is slidably fitted to define a pressure chamber 20 between the piston 19 and the end wall of the valve case 2, and the pressure chamber 20 is An air chamber 23 of an air spring 22 of a suspension device is provided in the pressure chamber 20 so that the piston 19 can delay the closing timing of the pressure reducing valves 5 ₁ and 5 ₂ via the balance lever 18 in response to an increase in the load. A brake hydraulic control device for a vehicle, characterized in that the communication path is provided with an orifice 28.