JPH0242707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a dual master cylinder to
A brake hydraulic pressure control device for a vehicle braking system, which has a brake hydraulic circuit configured into two independent systems, in particular a brake hydraulic pressure system that supplies hydraulic pressure lower than the front wheel brake hydraulic pressure as the rear wheel brake hydraulic pressure. This relates to a control device.

Conventionally, as shown in FIG.
Mutually independent first and second flow paths L ₁ and L ₂ extending from the output side of the dual master cylinder M are connected to the hydraulic operating parts of the rear wheel brakes Bf, Br' and Bf', Br, respectively. There is a format that does this. In this type of braking system, during heavy braking, each rear wheel brake hydraulic pressure is automatically reduced at a fixed ratio to the front wheel brake hydraulic pressure of the same system, and the load on the rear wheels is reduced by tilting the vehicle forward. In order to obtain efficient braking even when the vehicle is in use, and to balance the left and right rear wheel braking hydraulic pressure so that equal braking force is applied to the left and right rear wheels, the first and second flow paths _L1 , _L2 is known to provide a common brake hydraulic control device C on the way to the rear wheel brakes Br, Br'.

By the way, such a common control device C has
When a pressure difference occurs between the first and second input hydraulic chambers during braking, it is necessary to reduce the pressure difference in order to balance the braking forces of the left and right rear wheels.

An object of the present invention is to provide a brake hydraulic pressure control device with a simple configuration that satisfies such requirements.

In order to achieve this object, the present invention provides a vehicle in which the output hydraulic pressure of a dual master cylinder is separately supplied to the hydraulic operating parts of a pair of left and right rear wheel brakes through first and second flow paths. In the braking device, a common housing is interposed in the middle of the first and second flow paths, a pair of left and right pressure receiving pistons are slid into cylinder holes in the housing, and the pressure receiving pistons are provided with the pressure receiving pistons on the inner end sides thereof. First and second input hydraulic chambers that communicate separately upstream of the first and second flow paths,
Further, first and second output hydraulic chambers are formed on the outer end side, respectively, and communicate with the downstream side of both flow paths, and the pressure receiving area of each pressure receiving piston on the side of each output hydraulic chamber is adjusted to the side of each input hydraulic chamber. The pressure receiving area is larger than that of the pressure receiving area, and the adjacent input and output hydraulic chambers are communicated via a valve that opens at the outward sliding limit of each pressure receiving piston and closes when it slides inward. A common pressure regulating spring is compressed between the pistons, and a balance piston having both ends facing the first and second input hydraulic pressure chambers is slid into the small cylinder holes of both pressure receiving pistons, and a balance piston is arranged opposite to the center of the balance piston. A pair of washers are provided which contact each shoulder and the inner end of each of the pressure receiving pistons adjacent to the shoulders so as to be able to separate from each other. The feature is that a common neutral spring with a weak spring force is compressed.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, the dual master cylinder M is configured in a tandem type. ₁ and ₂ are the first and second output ports, respectively.
Pressure oil can be fed from P ₁ and P ₂ to the first and second flow paths L ₁ and L ₂ , and this pressure oil is
It is guided to the front wheel brakes Bf, Bf' and the brake hydraulic control device C.

The brake hydraulic control device C is configured symmetrically, and its left and right housings 3 ₁ and 3 ₂ are joined to each other by bolts 5 and nuts 6 via flanges 4 ₁ and 4 ₂ . In the housings 3 ₁ and 3 ₂ ,
Cylinder holes 7 ₁ , 7 ₂ and a larger diameter hole 8
₁ , 8 ₂ are formed, and each cylinder hole 7 ₁ ,
Pressure receiving pistons 9 ₁ and 9 ₂ having the same diameter are slidably connected to each other on 7 ₂ . Small cylinder holes 10 ₁ , 10 ₂ having the same diameter are formed in each pressure receiving piston 9 ₁ , 9 ₂ , and these small cylinder holes 10 ₁ , 10 ₂ have
Both ends of the balance piston 11 are in sliding contact with each other. In the illustrated example, the balance piston 11 is divided into left and right parts at the center for processing and assembly reasons, but it is functionally the same as a single piston.

A common strong pressure regulating spring 12 is compressed between both pressure receiving pistons 9 ₁ and 9 ₂ . In addition, a pair of shoulders 13 ₁ facing each other is provided at the center of the balance piston 11 .
13 ₂ is formed, and each shoulder portion 13 ₁ , 13
₂ and the inner end portions 15 ₁ , 15 ₂ of the respective pressure-receiving pistons 9 ₁ , 9 ₂ adjacent thereto are provided with a pair of left and right washers 16 ₁ , _{16 2} that are in separable contact with each other. A neutral spring 17 having a weaker spring force than the pressure regulating spring 12 is compressed between _{the two} .

Both small cylinder holes 10 ₁ and 10 ₂ are provided with first and second cylinders by both ends of the balance piston 11.
The input hydraulic chambers 18 ₁ , 18 ₂ are connected to the cylinder holes 7 ₁ , 7 ₂ , and the first and second output hydraulic chambers 19 ₁ , 19 ₂ are connected to the outer ends of the pressure receiving pistons 9 ₁ , 9 ₂ , respectively. The first and second input hydraulic chambers 18 ₁ , 18 ₂ are connected to the upstream side of the first and second flow paths L ₁ , L ₂ via inflow ports 20 ₁ , 20 ₂ , and
The downstream ends of both flow paths L ₁ and L ₂ are connected to the first and second output hydraulic chambers 19 ₁ and 19 ₂ via outflow ports 21 ₁ and 21 ₂ so as to be in constant communication with each other.

The end walls of the small cylinder holes 10 ₁ and 10 ₂ are provided between adjacent input and output hydraulic chambers 18 ₁ and 19 ₁ and between the adjacent input and output hydraulic chambers 18 1 and 18 ₂ , 1
Communication holes 22 ₁ , 22 ₂ are provided to communicate between the valve opening rods _{24 1} , ₂₄ , which project from the outer ends of the valves _{23 1 ,} 23 ₂ , respectively. ₂ penetrates. Each valve 23 ₁ , 23 ₂
A closing spring 25 is provided between the balance piston 11 and the balance piston 11.
₁ and 25 ₂ are respectively contracted, and normally the valve opening rods 24 ₁ and 24 ₂ of the valves 23 ₁ and 23 ₂ abut against the end walls of the cylinder holes 7 ₁ and 7 ₂ , and each pressure receiving piston 9
The valves 23 ₁ and 23 ₂ are held in the open position at the outward sliding limits of ₁ and 9 ₂ . The closing springs 25 ₁ and 25 ₂ are set to have a weaker spring force than the neutral spring 17. When the pressure receiving pistons 9 ₁ , 9 ₂ move inward and the end walls of the small cylinder holes 10 ₁ , 10 ₂ come into contact with the valves ₂₃ 1 , 23 ₂ , the communication holes 22 ₁ , 2
2 ₂ is occluded.

Connectors 26 ₁ and 26 ₂ are attached to the inner ends of each valve 23 ₁ and 23 ₂ , respectively. The inner ends of these connectors 26 ₁ and 26 ₂ are slidably fitted to the outer ends of the balance piston 11, so that the valves 23 ₁ and 23 ₂ and the balance piston do not interfere with each other within the normal operating range. I've learned not to.

A small hole 28 communicating with the outside is provided at the joint between the housings 3 ₁ and 3 ₂ , and a seal ring 29 is provided inside this joint to prevent dust from entering from the outside. . This seal ring 29 has a one-way flow function that allows hydraulic oil etc. to flow from the inside to the outside, and is a seal between the pressure receiving pistons 9 ₁ , 9 ₂ and the cylinder holes 7 ₁ , 7 _{2 .} If the members 30 ₁ , 30 ₂ , etc. are worn and damaged and hydraulic oil leaks into the large diameter holes 8 ₁ , 8 ₂ , the hydraulic oil will flow out through the seal ring 29 and the small hole 28 to prevent the failure. This can be detected as an abnormal drop in the oil level in the reservoir of cylinder M.

Next, the operation of this embodiment will be explained.
When the master cylinder M is not operating, both the left and right pressure receiving pistons 9 ₁ and 9 ₂ are mainly operated by the pressure regulating spring 1
2, the valves 23 ₁ and 23 ₂ are opened, and the pressure is applied between the first and second input and output hydraulic chambers 18 ₁ and 19 ₁ and between the hydraulic chambers 18 2 and 18 ₂ , respectively. 19 ₂ are in communication with each other.

Further, the neutral spring 17 is connected to the opposing shoulders 13 ₁ , 13 ₂ of the balance piston 11 via washers 16 ₁ to 15 _{2 .}
by pressing outward, respectively, to release the shoulders 13 ₁ ,
13 ₂ is aligned with the position of the corresponding inner end portions 15 ₁ and 15 ₂ of the pressure receiving pistons 9 ₁ to 9 ₂ , whereby the balance piston 11 is held at a neutral position that is not biased in either the left or right direction.

Therefore, when the brake pedal 1 is operated here, the output hydraulic pressure of the master cylinder M is transmitted to each downstream of the first and second flow paths L ₁ and L ₂ , and the front and rear wheel brakes Bf, Bf' and Br are , Br′ operate simultaneously.

Then, as the output oil pressure of the master cylinder M increases, the first and second input and output oil pressure chambers 18 ₁ , 19 ₁
The pressure inside the pressure receiving pistons 9 ₁ , 19 ₂ also rises, but when the pressure reaches a certain value, the difference in the pressure receiving areas between the inner and outer ends of the pressure receiving pistons 9 ₁ , 9 _{2 increases} .
The differential oil pressure acting on the pressure regulating spring ₁₂ and the neutral spring 17 becomes larger than the set load of the pressure regulating spring 12 and the neutral spring 17, and the pressure receiving pistons 9 ₁ and 9 ₂ slide inward while compressing the pressure regulating spring 12 and the neutral spring 17, respectively. When the amount of inward movement exceeds a certain value, each valve 23 ₁ , 2
3 ₂ closes each communication hole 22 ₁ , 22 ₂ . and,
During this time, the brake oil pressure for the rear wheels does not increase.

When the output hydraulic pressure of the master cylinder M further increases, the pressure within the input hydraulic chambers 18 ₁ and 18 ₂ increases, pushing each pressure receiving piston 9 ₁ and 9 ₂ outward.
Therefore, the valves 23 ₁ , 23 ₂ open again, increasing the pressure in the output hydraulic chambers 19 ₁ , 19 ₂ . When this pressure reaches a certain value, the pressure receiving piston 9 ₁ ,
9 ₂ is activated again, the communication holes 22 ₁ and 22 ₂ are closed, and the increase in pressure is stopped. By repeating these actions, the braking oil pressure for each rear wheel gradually increases.

Since the load of the common pressure regulating spring 12 acting on both the pressure receiving pistons 9, 9 is naturally equal, the pressure reduction start points of the left and right rear wheel braking oil pressures can be made to coincide. Also, the piston 2 ₁ of the master cylinder M,
If a pressure difference occurs between the first and second input hydraulic chambers 18 ₁ and 18 ₂ due to a difference in the operating timing of the valves 2 ₂ , the balance piston 11 compresses the neutral spring 17 from the neutral position. However, by moving to the low-pressure side, the pressures in both input hydraulic chambers 18 ₁ and 18 ₂ can be approximately balanced, and thus braking hydraulic pressure, that is, braking force, can be applied approximately equally to the left and right rear wheels.
When the pressure difference between the input hydraulic chambers 18 ₁ and 18 ₂ is eliminated, the balance piston 11 can return to the neutral position again by the cooperative action of the neutral spring 17 and the washers 16 ₁ and 16 ₂ .

On the other hand, since the output hydraulic pressure of the master cylinder M directly acts on the front wheel brakes Bf, Bf', the front wheel braking hydraulic pressure increases rapidly as the output hydraulic pressure of the master cylinder M increases. In this way, when braking is applied strongly, the front wheel brakes Bf and Bf' are applied more strongly to the front wheel on the side where the vehicle body leans forward and the downward load increases.
Rear brake for the rear wheel on the side where the load is reduced
Since Br and Br' are operated weakly, efficient braking can be performed without causing skids in each wheel.

As described above, according to the present invention, a common housing is interposed in the middle of the first and second flow paths, and a pair of left and right pressure receiving pistons are slidably connected to the cylinder holes in the housing, and the inner parts of these pressure receiving pistons are A first channel is provided at the end side and communicates separately with the upstream side of the first and second flow paths.
and a second input hydraulic chamber, and first and second output hydraulic chambers are respectively formed on the outer end side, each communicating with the downstream of both flow paths, and the output hydraulic chamber of each pressure receiving piston is formed on the output hydraulic chamber side of each pressure receiving piston. The pressure-receiving area is larger than the pressure-receiving area of each input hydraulic chamber, and a valve is provided between each adjacent input and output hydraulic chambers that opens at the outward sliding limit of each pressure-receiving piston and closes when it slides inward. a common pressure regulating spring is compressed between both the pressure receiving pistons, and
A balance piston having both ends facing the first and second input hydraulic pressure chambers is slidably fitted into the small cylinder holes of both the pressure receiving pistons, and a pair of opposing shoulders is formed in the center of the balance piston. A pair of washers are provided in contact with the inner end of each of the pressure receiving pistons adjacent thereto in a separable manner, and a common neutral spring having a weaker spring force than the pressure regulating spring is compressed between the two washers. Therefore, during braking, when the pressure in the first and second input hydraulic chambers rises above a predetermined value by the cooperation of the pair of pressure receiving pistons, the common pressure regulating spring, and the valve, those pressures are transferred to the first and second output hydraulic pressure chambers. The pressure can be reduced and transmitted to the chamber at a constant ratio, and in particular, by using a common pressure regulating spring, it is possible to reliably match the pressure reduction start pressures of both output hydraulic chambers.

In addition, when not braking, the pair of washers and the common neutral spring work together to hold the balance piston in a neutral position that is not biased to either side of the first and second input hydraulic chambers, and as a result, when braking , when a pressure difference occurs between both input hydraulic chambers, the balance piston can accurately balance the pressures of both input hydraulic chambers, and in combination with the same depressurization start pressure of both output hydraulic chambers, the left and right The rear wheel brake can be operated accurately and in a well-balanced manner.

Moreover, as mentioned above, one common pressure regulating spring is sufficient for a pair of pressure receiving pistons, and one common neutral spring is sufficient for a pair of washers, which improves performance and simplifies the structure as described above. It is possible to achieve both.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of a braking device for a vehicle, and FIG. 2 is a longitudinal sectional plan view of essential parts showing an embodiment of the device of the present invention. M... Master cylinder, L ₁ , L ₂ ... First and second flow paths, Br, Br'... Rear wheel brake, C... Braking hydraulic control device, 3 ₁ , 3 ₂ ... Housing, 7 ₁ ，
7 ₂ ... Cylinder hole, 9 ₁ , 9 ₂ ... Pressure receiving piston,
10 ₁ , 10 ₂ ... small cylinder hole, 11 ... balance piston, 12 ... pressure regulating spring, 13 ₁ , 13 ₂ ...
... Shoulder of balance piston, 15 ₁ , 15 ₂ ... Inner end of pressure receiving piston, 17 ... Neutral spring, 18 ₁ ,
18 ₂ ...first and second input hydraulic chambers, 19 ₁ , 19
₂ ...First and second output hydraulic chambers, 22 ₁ , 22 ₂ ...
...Communication hole, 23 ₁ , 23 ₂ ...Valve, 26 ₁ , 2
6 ₂ ...Connector.

Claims (1)

[Claims] 1 The output oil pressure of the dual master cylinder M is
In a vehicle braking system, the brake system for a vehicle is configured to separately supply hydraulic pressure to the hydraulic operating parts of a pair of left and right rear wheel brakes Br, Br _' through the second flow paths L ₁ , L ₂ . Common housing 3 ₁ in the middle of L ₂ ,
3 ₂ is interposed, and a pair of left and right pressure receiving pistons 9 ₁ , are installed in the cylinder holes 7 ₁ , 7 ₂ in the housings 3 ₁ , 3 ₂ .
9 ₂ are slid together, and first and second input hydraulic pressure chambers 18 are connected to the inner end sides of these pressure receiving pistons 9 ₁ and 9 ₂ and communicated with the upstream sides of the first and second flow paths L ₁ and L ₂ respectively. ₁ ,
18 ₂ , and first and second output hydraulic chambers 1 each communicating with the downstream of both flow paths L ₁ and L ₂ on the outer end side.
9 ₁ and 19 ₂ respectively, and the pressure receiving area on the output hydraulic chamber 19 ₁ , 19 ₂ side of each pressure receiving piston 9 ₁ , 9 ₂ is made larger than the pressure receiving area on the input hydraulic chamber 18 ₁ , 18 ₂ side. , between each adjacent input and output hydraulic chambers,
Communication is provided between the pressure receiving pistons 9 ₁ and 9 ₂ through valves 23 ₁ and 23 ₂ that open at the limit of outward sliding of each of the pressure receiving pistons 9 ₁ and 9 ₂ and close when sliding inward. A common pressure regulating spring 12 is compressed, and a balance piston 11 with both ends facing the first and second input hydraulic chambers 18 ₁ , 18 ₂ is inserted into the small cylinder holes 10 ₁ , of both the pressure receiving pistons 9 ₁ , 9 ₂ . A pair of shoulder portions ₁ that slide against the balance piston 11 and are opposed to each other at the center of the balance piston 11.
3 ₁ , 13 ₂ , and a pair of washers 16 ₁ , which abut on the respective shoulder portions 13 ₁ , 13 ₂ and the inner end portions of the respective pressure receiving pistons 9 ₁ , 9 ₂ adjacent thereto in a separable manner.
16 ₂ and a common neutral spring 17 having a weaker spring force than the pressure regulating spring 12 is compressed between the washers 16 ₁ and 16 ₂ . Device.