JPH04505142A - Brake pressure reducing valve assembly - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Brake pressure reducing valve assembly The present invention provides a brake that is supplied to the front brake actuator under certain braking conditions. Supplying brake pressure lower than rake pressure to the vehicle's rear wheel brake actuator The present invention relates to a brake pressure reducing valve assembly for a vehicle brake Wffi.

Vehicle brake equipment! For, when applying the brake, a certain marginal value ( Until the rear wheel brake pressure reaches the front wheel brake pressure (referred to as cut-in pressure) When the brakes are applied further, the rear brake pressure increases at a speed equal to It is recognized that it is desirable for the force to increase at a slower rate than the front brake pressure. It is. The desired result is that there is a Alternatively, it can be realized by providing two or more pressure reducing valves.

It is known that such pressure reducing valves are completely pressure responsive. Typical of this type A known valve is illustrated in FIG. 1, and the output characteristics of this valve are indicated by the broken line OAB in FIG. It is illustrated. Vehicles with only a driver on board and fully loaded The calculated ideal braking characteristics are also illustrated in FIG. In Figure 1 The simple pressure-responsive pressure reducing valve shown has ideal characteristics when only the driver is on board. but not well matched to ideal properties under fully loaded conditions.

As a result, the available braking force is significantly insufficient under fully loaded conditions. Otherwise, it will not be used.

It is also known to manufacture pressure reducing valves that respond to the deceleration of the vehicle to which they are installed. be. A typical known valve of this type is illustrated in FIG. It can be seen that it is equipped with a valve body that accommodates a piston and a ball. This valve body , on the vehicle so that the ball is seated on a slope that extends upward toward the front of the vehicle. The direction is determined. When in use, the ball transfers upward along the slope and steps The deceleration force of the vehicle is such that it closes the central passage provided in the piston. Until then, the inlet pressure is freely communicated to the outlet of the valve. The central passage was closed. In other words, the inlet pressure acting on the small diameter part of the stepped piston is applied to the large area part of the piston. until the piston can move against the outlet pressure acting on the inlet pressure Further increases in force will not further increase the outlet pressure.

The characteristics of such a valve are illustrated in FIG. With only the driver on board , until point C is reached, the outlet pressure increases at the same rate as the inlet pressure, and at point 0, the sufficient brake force to provide the necessary deceleration I to move the door and isolate the exit from the inlet. pressure. After the outlet is isolated from the inlet by the ball, the inlet pressure is Even if it is increased further, the outlet pressure will not increase until it reaches point D. and when the inlet pressure is further increased, the rate at which the inlet pressure increases is slower than The outlet pressure increases with velocity. When the brakes are applied under a fully loaded condition, the inlet pressure The force increases at the same speed as the exit pressure, and when point F is reached, the brake pressure moves the ball. Thus, sufficient deceleration can be achieved to isolate the inlet from the outlet. the Afterwards, the outlet pressure remains constant, while the inlet pressure increases until it reaches point E, and then After that, the outlet pressure increases again, but the rate of increase is faster than the rate at which the inlet pressure increases. slower than the degree. The characteristics plotted in Figure 4 are ideal for fully loaded conditions. It can be seen that the characteristics fit slightly better than those in FIG.

However, vacuum response valves of the type shown in FIG. 3 suffer from a number of well-known drawbacks.

First, the valve characteristics are more perfect than those provided by a pure pressure-responsive pressure reducing valve. Closer to ideal properties at all loading conditions, but less well matched Rear wheel braking is still insufficient and should therefore be utilized under fully loaded conditions. Unable to fully utilize power. The cause of this poor fit is at least Some are designed so that the outlet pressure does not increase after the ball moves and isolates the inlet from the outlet. At the same time, the inlet pressure must be increased significantly. Also, ah Under normal driving conditions, especially when driving down steep slopes, Even at relatively low brake pressures, or even before applying the brakes, the ball It is possible to transfer and engage the piston end. For example, going down a steep downhill slope When the driver engages low gear to gradually decelerate the vehicle when If you apply the brakes during that transitional deceleration, when you apply the brakes the ball will is already engaged with the piston. This allows the outlet pressure will increase along +11il ODE, and the use of rear wheel brake pressure will be extremely It becomes insufficient. Utilization of such insufficient brake pressure is exactly the ideal brake. This occurs when key efficiency is required, such as when descending a steep slope. I want to be noticed. Deceleration-responsive valves of various practical designs make braking extremely A valve is installed to prevent excessive rear brake pressure from being applied when applied suddenly. The ball should be designed so that it can move in part in response to the fluid flow rate between the inlet and outlet of the Another disadvantage is that it must be done. This is difficult to achieve in practice, and Because the viscosity of the rake fluid changes at different temperatures, it is difficult to achieve consistent results. It is particularly difficult.

Preferred embodiments of the present invention solve or alleviate the above-mentioned problems and provide pressure Significantly improved characteristics compared to both responsive pressure reducing valves and pure deceleration responsive valves The present invention provides a fairly simple and low cost valve.

According to one embodiment of the invention, a brake pressure reducing valve assembly for a vehicle braking system includes a valve body and an inlet defined within the valve body and connectable to a source of brake actuation fluid. an outlet chamber defined within the valve body and connectable to a brake actuator; normal oven valve means providing communication between the chamber and the inlet and outlet chambers; In response to the deceleration of the vehicle to which the valve assembly is attached exceeding a critical value, the valve hand a deceleration responsive member that closes the stage and the pressure within the exit chamber is below a predetermined M; means for preventing the valve from being closed by the deceleration response means when the deceleration response means Ru.

The means for preventing blockage of this valve means is provided when traveling downhill as described above. To solve the problem that the valve means is blocked too early in the process. Examples of the present invention the valve reaches a certain critical pressure value regardless of whether the deceleration responsive member is actuated or not. remains open to provide rear brake pressure equal to front brake pressure. Ru. In a preferred embodiment of the invention, the predetermined pressure is to match the desired cut-in pressure in the case. The valve means is capable of Operates in response to an increase in inlet pressure, and the output is less than the increase in inlet pressure. A key that increases mouth pressure! (metering) valve is desirable. Therefore, the book In a preferred embodiment of the invention, after the valve means has been occluded by the deceleration responsive member, the As the inlet pressure increases further, the outlet pressure is reduced to a deceleration-responsive depressurization of the type shown in diagram N3. The static pressure of the valve will increase instead of exhibiting a low pressure characteristic.

In particularly preferred embodiments of the invention, the deceleration responsive member is required to occlude the valve means. The required deceleration limit value is not constant under all conditions; increases as the outlet pressure increases. In other words, the deceleration response member brake higher than a predetermined value to achieve sufficient deceleration to occlude the valve means. If pressure is required, the deceleration responsive member is required to occlude the valve means. The deceleration given by the outlet pressure of a predetermined value is the deceleration that greater than the value that would be required if it were sufficient to occlude the valve means. will be the value. This property allows the valve to match its ideal properties under fully loaded conditions. It becomes possible to provide well-matched exit characteristics. In practice, the force, toine pressure, is Not only the deceleration of the vehicle, but also the braking required to achieve that deceleration. It is also determined by the pressure. The vehicle is fully loaded and there is no special deceleration. Fully loaded vehicle when high brake pressure is required to achieve In order to make better use of the large braking force of the available rear wheels, Therefore, the cut-in pressure is increased.

In a particularly preferred embodiment of the invention, the deceleration responsive member is configured such that the fluid is applied during braking. does not flow through the member and therefore movement of the member is dependent on brake fluid flow rate or brake fluid flow. The position should be such that it is not significantly affected by the velocity of the fluid! It is decided. present invention In particularly preferred embodiments, the deceleration responsive member is configured to require a deceleration response to move the valve member. the valve member of the valve means in such a manner that it is necessary to overcome the inertia of the responsive member. engage with. This configuration results in a very rapid increase in brake pressure. , the deceleration-responsive member when the cooperating valve seat moves with great rapidity towards the valve member. The inertial force of the valve member holds the valve member in place and prevents it from cooperating with the rapidly moving valve seat. You will be given the benefit of support. By this means, the valve member does not block the valve seat. , the frequency of moving with the rapidly moving valve seat is significantly reduced, so that the brake When the key is applied too widely and suddenly, in the deceleration I-responsive valve of the present invention, the The tendency for constant high pressure to be introduced is avoided.

The invention is based on the following detailed description, given by way of example only and with reference to the accompanying drawings. You can understand it better by reading it.

Figure 1 is a schematic diagram of a pressure-responsive pressure reducing valve according to the prior art, and Figure 2 is a schematic diagram of a pressure-responsive pressure reducing valve according to the prior art. For fully loaded and driver-only conditions, as well as the actual characteristics provided. A graph of outlet pressure versus inlet pressure showing the ideal valve characteristics for Fig. 3 is a diagram showing a deceleration responsive pressure reducing valve according to the prior art, and Fig. 4 is a diagram showing the characteristics of the valve shown in Fig. 3. A graph corresponding to FIG. 2 showing the characteristics, FIG. 5 is a diagram of the first embodiment of the present invention, 6 is a graph corresponding to FIG. 1 showing the characteristics of the valve shown in FIG. 5, and FIG. 7 is a graph showing the characteristics of the valve of the present invention. A diagram of the second embodiment, FIG. 8 is a graph that is half of FIG. 6 showing the characteristics of the valve in FIG. 7, and FIG. 9 is a graph showing the characteristics of the valve of the present invention. A diagram of a third embodiment, FIG. 10 is a diagram showing the characteristics of the valve of FIG. 9.

Referring first to FIG. 5, the illustrated brake pressure reducing valve 1 has an inlet chamber 3 and It comprises a valve body 2 defining an outlet chamber 4 . This inlet chamber 3 has an inlet connection. Via the fitting 5, a source of brake working fluid, such as a hydraulic master cylinder, for example. It is possible to connect to The outlet chamber 4 is connected via an outlet connection 6, for example to a drum brake. - Connected to a brake actuator such as a brake cylinder.

A ratio in which the piston 7 is slidably mounted within the valve body and exposed to the outlet chamber 4 It is exposed to the atmosphere through a relatively large area portion A2 and a vent hole 8 formed in the valve body. A relatively small area portion A. have. Shows the difference between the same area parts A2 and Ao The annular head A1 is exposed to the working pressure in the inlet chamber 3.

The piston 7 is biased towards the outlet chamber 4 by the spring 9 and the radial bore 10 and a passage connecting the inlet chamber 3 to the outlet chamber 4 via the axial bore 11. provide One end of this passage 11 forms a valve seat 12, and the valve member 13 is connected to this valve seat 12. Together they close the passageway 10.11 to fluid flow. Standstill of the valve shown in Figure 5 In position, the valve member 13 abuts the end wall 14 of the valve body and is inserted into the cage-shaped interior of the piston. It is abutted by a ball 15 held within a central portion 16. This piston has spring 9 It is thus biased and comes into contact with the ball 15, so that in the rest position shown, The valve member 13 is kept separate from the valve seat 12 and is connected to the inlet chamber 3 and the outlet chamber. There is a confession connection between Chamber 4.

The valve assembly 1 is mounted on the vehicle body as shown, and the longitudinal axis of the piston is Slanted upward toward the front of the object.

In use, if the brake is applied at normal speed, fluid flows into the inlet chamber 3, Exit from prosthesis 5 through radial passageway 10, hole 11 and exit chamber 4 Flows to fitting 6, and during the initial phase of pressure build-up, the pressure at outlet 6 reaches population 5. It is approximately equal to the pressure at The increase in brake pressure slows the vehicle. area Part A. When the brake pressure acting on overcomes the force of spring 9, piston 7 exits It moves in the direction away from the chamber 4. If the driver is the only person on board the vehicle , as mentioned above, the brake pressure required to move the piston is When moving away from the outlet chamber 4, the ball 15 is provided by the cage 16. This is sufficient to create a critical deceleration that causes upward movement along slope 17. subordinate Thus, when the piston moves away from the outlet chamber, the valve member 13 As illustrated by 5! is retained in the valve seat 12 and is engaged with the inlet chamber 3 and the outlet chamber 3. Communication between the mouth chambers 4 is cut off. If the brake population pressure increases further, this is applied to the piston 7 over the area A, and therefore The valve member 13 acts as a metering valve and increases the pressure at the outlet 6 (inlet 5 pressure increase). The above characteristics are illustrated by the line OXY in Figure 6. It is.

Since the driver and other persons are on board the vehicle, the piston 7 cannot be moved as described above. The loss of the vehicle created by sufficient pressure to cause it to separate from the exit chamber If the velocity is insufficient to displace the ball 15 upwards along the slope 17, The ball 15 is attached to the piston 7 as the piston moves away from the exit chamber. It is located in the position shown in the figure. Therefore, the valve member 13 moves together with the piston 7, and the valve body It is in a non-contact state with the end wall 14 of. Therefore, when the piston 7 starts moving, the inlet Communication between chamber 3 and outlet chamber 4 is not interrupted. Brake pressure increases even more. If it is increased, the deceleration of the vehicle further increases, causing the ball 15 to move upward along the slope 17. and thereby move the valve member 13 into engagement with the valve seat 12 while inlet Communication between chamber 3 and outlet chamber 4 is cut off. Therefore, the inlet pressure increases further. This pressure then acts on the area A1 and directs the piston 7 towards the outlet chamber 4. and increases the pressure at outlet 6 to a lesser extent than the increase at inlet 5. let Finally, the piston 7 has moved sufficiently towards the outlet chamber 4 and the valve member 13 When the valve member 13 is brought into contact with the end wall 14, the valve member 13 is lifted from the valve seat 12 and the metering valve continues to supply pressure fluid to the outlet 6. Under fully loaded conditions, The characteristics of the valve of FIG. 5 are indicated by the line oxzy in FIG.

until the pressure within the valve body acting on area A0 is sufficient to overcome the force of spring 9. , it will be understood that it is not possible for the valve 13 to engage the valve seat 12. Therefore , a deceleration responsive member isolates the inlet from the outlet before applying brake pressure. The above-mentioned problems of the prior art are completely avoided.

It stands to reason that in order to move the valve member 13, the ball 15 must also move. It will be understood. Therefore, it is possible to overcome the inertial force of the ball 15 before moving the member 13. is necessary. If the brakes are applied very suddenly, the piston 7 will It is possible to move very rapidly away from the member 4. in this case , ball 15 maintains valve member 13 in the position shown so that valve seat 12 is very It suddenly engages the valve member 13 and isolates the outlet chamber 4 from the inlet chamber 3.

This creates a very high pressure downstream of the valve, as in prior art deceleration-responsive pressure reducing valves. This is particularly desirable because it prevents the incorporation of

Furthermore, although the ball 15 is mounted within the inlet chamber 3, the inlet chamber It is virtually isolated from the dynamic effects of the fluid flowing through it and therefore the valve The action of the fluid is not controlled by the flow rate of the fluid or the velocity of the hydraulic fluid.

Referring now to FIG. 7, a second embodiment of the present invention is illustrated. in this case , the valve body 2A has an inlet chamber 3A and an outlet chamber 4A'1-Ji. Entrance chi When in use, chamber 3A is connected to a source of brake hydraulic fluid via inlet fitting 5A. while the outlet chamber 4A is connected to the brake actuator via the outlet fitting 6A. connected to the The stepped piston 7A is slidably mounted inside the valve body. and is biased toward the exit chamber by spring 9A. Series of radial and axial Directional passages 10A, IIA are normally open to inlet chamber 3A and outlet chamber 4 Provide communication (of a normal oven). The valve member 13A is formed on the piston. works with the valve seat 12A to cut off communication between the inlet chamber 3A and the outlet chamber 4. I can do something. Valve member 13A is mounted within 80 chamber 14A and has an inclined surface. It is coupled via a ring 18 to the ball 15A seated on the ball 17A. this pole The 15 players are loosely fitted in the ring 18, so the ball 15A is When using the valve, it is possible to move along the slope 17A.

In use, the valve is installed as shown in Figure 7, with the axis of the piston aligned with the vehicle. It slopes upward in the direction of the surface. Static pressure value! , the components are spring 9A Illustrated better! The inlet chamber 3A, passage 10A, IIA and outlet There is free communication between the entrance 5A and the exit 6 via the soil collar 4A. entrance When the pressure increases, the outlet pressure also increases at the same speed and acts on the area AO. The pressure within the valve body to overcome the force of spring 9A is sufficient to The stone moves away from the exit chamber 4A. At this pressure, the deceleration of the vehicle is If the ball is sufficient to keep the ring 15A at the top of the slope 17A, the ball 18 on the valve member 13A and maintains the valve member 13A-1 in the position shown. hold Therefore, when the piston 7A moves, the valve seat 12A is engaged with the valve member 13A. , the communication between the inlet chamber and the outlet chamber is cut off. Then the inlet pressure As the population pressure increases further, the valve member 13A functions as a metering valve and the rate at which the population pressure increases Increase the outlet pressure to the desired extent at slower speed I.

Due to the loading of the vehicle, the deceleration caused by the brake pressure or the force on the spring 9 is sufficient to move the piston 7A against the If it is insufficient to maintain it at the top, the ball 15A will descend along the slope and reach the top. When the piston 7A moves, it follows the piston 7A. Therefore, the valve member 13A The valve seat 12A is held in a disengaged state, and if the inlet pressure increases further, the increase All pressures are communicated to ratio 06A. The vehicle decelerates and the ball 15A falls on the slope 17A. When the outlet pressure increases enough to move upward along Then, the valve member 13A is brought into contact with the valve seat 12A, and then the valve is moved to the ajl position as described above. (Metering) Acts as a valve.

Further advantageous features of the valve of FIG. 5 can be obtained from the valve shown in FIG.

When the slope 17A moves away from the axis of the piston toward the rear of the vehicle, i.e. , when the slope of the slope 17A increases toward the lower end of the slope, the valve of FIG. Another advantageous feature is obtained. The advantage of this configuration is that the vehicle is loaded with more than the driver. Therefore, when the piston 7A starts moving, the deceleration of the vehicle causes the ball 15A to tilt. If insufficient to maintain the ball 15A at the top of the surface 17A, The deceleration required to move the ball upward along slope 17A is The more you work, the more you will gradually grow. This effect is due to the valve cut-in pressure The force is used not only to decelerate a vehicle, but also to the brakes required to achieve a specific level of deceleration. The purpose is to also be influenced by the pressure value.

For example, if the vehicle is fully loaded, the piston 7A will move away from the exit chamber. If the ball moves a considerable distance in the opposite direction and the driver is the only person on board, A deceleration is achieved that is sufficient to maintain A at the top of slope 17A. However, this Until the point in time, the ball 15A is on the steep part of the slope 17A, so the deceleration water is The level is insufficient to push ball 15A back upward along the slope, and ball 15A Higher brake pressure would be required to move A. This configuration The effect is to reduce the fully loaded force and pressure to ideal characteristics under fully loaded conditions. substantially closer together, thereby reducing rear brake utilization under full fh loading conditions. This can significantly improve performance.

The features of the valve in FIG. 7 are illustrated in FIG. The same reference numerals are used. Only the operator of the valve shown in Figure 7 is on board. The condition corresponds to the valve of FIG. However, in region Z1 of Fig. 7, that is, in a completely loaded state The cut-in pressure at the ideal fully loaded state is lower than the corresponding point in Figure 5. The characteristics are closer to the ideal characteristics of the full delta loading condition, and therefore better than the ideal characteristics of the fully delta loading condition. Compatible.

Although the present invention has been described with reference to the case where the ball is used as a deceleration response member, for example, Any other suitable deceleration responsive member, such as a roller, may be used in place of the ball. You can also do that.

Referring now to FIG. 9, yet another embodiment of the present invention is illustrated. child In this embodiment, the pressure reducing valve 100 has an inlet chamber 103 and an outlet chamber 10. 4 is provided with a valve body 102 defined therein. The inlet chamber 103 is connected to the inlet fitting 10 5 can be connected to a source of brake actuation fluid, e.g. a hydraulic mask cylinder. while the outlet chamber 104 is connected to the brake actuator via an outlet fitting 106. connected to the tuator. A piston 107 is slidably mounted within the valve body; A relatively large area portion A2 exposed to the outlet chamber 104 and a valve body are formed. It has a relatively small area 880 that is exposed to the atmosphere through the ventilation passage 108. Ru.

The annular area A1 indicating the difference between these area parts A2 and 〇 is entered Lochanno'103 exposed to internal working pressure.

Piston 107 is biased toward outlet chamber 104 by spring 109. an axially extending passageway connecting the inlet chamber 103 to the outlet chamber 104; 111. One end of this passage 111 is located at the center of the cage-shaped piston 1070. can be engaged by surface 113 of ball 115 positioned within portion 116 A valve seat 12 is formed. , in the usual illustrated form of the structure 1i5 element, the piston 107 is biased by a spring 109 and contacts the shoulder portion 110 of the valve body 102; Ball 115 is separated from valve seat 12 by gravity and spring loaded plunger 114 be held as such.

In use, the pressure within the valve body overcomes the force of spring 109 and moves piston 107 to the right. The a-path 111 is in free communication between the inlet 105 and the outlet 106 until Let it pass.

As in the embodiments described above, when only the driver is on board, the spring 109 The braking force required to move piston 107 against the force of creates a deceleration sufficient to deflect the ball 105 to the left as it moves to the right. let Therefore, in a state where only the driver is on board, the ball is moved to the piston 107. remains in contact with the plunger as the piston moves to the right, causing the piston to After moving the normal gap distance between the valve seat 112 and the valve seat 12, the valve seat 112 engages the surface 113. , communication from the inlet 105 to the outlet 106 is cut off.

If the pressure at the inlet 105 increases further, this increased pressure will appear on the area A1. This tends to move the piston 107 toward the left. Plunger 114 The strength of the spring 118 acting upward is such that when the pistons 1 and 07 move again to the left, such as in the inlet chamber 103 acting on the ball 115 on the area of the valve seat 112. The higher pressure is selected to be sufficient to compress spring 118. In other words , if the valve seat 12 engages the ball 115, the inlet pressure increases further; The ball and piston move to the left as a single unit, and the spring 118 pushes the ball. is not sufficient to separate it from the valve seat. Therefore, when only the driver is on board ( When the population pressure on line XL in Figure 10 further increases, both the piston and the ball move to the left. the outlet pressure increases at a slower rate than the rate at which the inlet pressure increases.

This continues until point Y in Figure 10 is reached, at which point the piston is again It engages with the shoulder portion 110. After that, even if the inlet pressure increases further, the ball 115 is pressed more firmly and engages with the valve seat 112. The outlet pressure will not increase. Therefore, if only the driver was installed, the Figure 10 The characteristics of ○XYZ are provided.

As in the embodiments described above, under fully loaded conditions, the force of spring 109 The deceleration provided by the pressure required to move the piston 107 through the sufficient to hold the ball 105 stationary relative to the valve body 102 as the valve moves. It is not possible to provide sufficient force to the ball, and the piston 109 moves to the right. Accordingly, the ball 115 also moves to the right. Inlet pressure causes ball 115 to slope 117 117A (depending on the actual load on the vehicle). It is only when the ball 115 engages the valve seat 112 that the inlet 10 5 and outlet 106 is cut off. Therefore, under full delta loading condition, the valve cover The seat-in pressure increases compared to when only the driver is on board.

Under fully loaded conditions, if the pressure at the inlet is higher than the cut-in pressure, In this case, the piston 107 and ball 115 move to the left as a single unit, directing the fluid to the rear wheel. of pressure at this outlet, as is clear to those skilled in the art, The increase is less than the increase in pressure at the inlet. Left side under these conditions Since the amount of displacement in the direction is relatively large, the piston 107 engages with the shield portion 110. Therefore, there is no upper limit on the pressure that can be applied to the rear brakes. do not have. Therefore, under fully loaded conditions, the valve forms the characteristic 0XAB of FIG. .

In the embodiment of FIG. 9, plunger 119 is a bore formed in piston 107. a cross that is slidably mounted within the piston and positioned within the oversized bore 121 of the piston; It carries a bottle 120. This cross pin 120 extends beyond the piston and thus Therefore, when the piston 107 moves by a predetermined amount, the cross pin 120 moves to the end face 1' of the valve body. Hit 22. After that, even if the bin 107 moves further to the right, and the vehicle decreases, Ball 105 is prevented from moving further to the right, regardless of speed.

The effect of this configuration is to maintain the cut-in pressure limit regardless of vehicle deceleration. It is to provide. A ball 115 is placed in the initial gap between the pin 120 and the end face 122. and the initial clearance between the valve seat 112, sufficient to move the piston 107. Once a sufficient brake pressure value is reached, the valve seat 112 is 105. This configuration allows the rear wheels to brake independently of the efficiency of the front brakes. It is particularly useful because it provides an upper limit for brake cut-in pressure. For this reason , under fully loaded conditions, e.g. if the brake pads heat up due to repeated use. If, as a result, the front wheels generate significantly less deceleration force than normal, the cut-in pressure The deceleration force generated by the force causes the ball 115 to move upward along the slope 117.117A. Cut-in pressure is reached even if there is not enough movement. Therefore, the rear wheel Premature locking of the rake is avoided.

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Claims (10)

[Claims] 1. A brake pressure reducing valve assembly for a vehicle brake system, comprising a valve body and a valve body. an inlet chamber defined within the valve body and connectable to a source of brake actuation fluid; an outlet chamber defined in the brake actuator and connectable to the brake actuator; and separating the inlet chamber from the outlet chamber; During the initial braking action, the piston is activated by the fluid pressure inside the valve body. biased in one axial direction and biased in the opposite axial direction by a biasing spring a positioned piston, a valve seat on the piston, and the inlet chamber; and a normally open valve means for providing communication between the outlet chamber and the outlet chamber. a valve member that is capable of cooperating with said valve seat; a deceleration responsive member for closing said valve means in response to a deceleration of said valve means; When there is no fluid pressure within the valve body, the spring causes the valve seat to engage the valve member. positioning and maintaining the piston so that it cannot mate with the valve; When the fluid pressure inside the body increases to a predetermined value, the piston moves against the spring. is moved by said fluid pressure against a biasing force of said valve seat into engagement with said valve member. Brake pressure reducing valve assembly, which is arranged to be in a position such that the Three-dimensional. 2. The brake pressure reducing valve assembly of claim 1, wherein the pressure in the outlet chamber is When the force is greater than or equal to the predetermined value, the position of the valve member relative to the valve seat decreases. A brake characterized in that it is controlled by a speed responsive member. Pressure reducing valve assembly. 3. The brake pressure reducing valve assembly according to claim 1 or 2, wherein the deceleration response The inertia of the member is adapted to resist movement of the valve member, thereby When the piston moves very rapidly, regardless of the deceleration of the vehicle, the valve A brake pressure reducer characterized in that a member is adapted to engage said valve seat. Pressure valve assembly. 4. The brake pressure reducing valve assembly according to claim 2, wherein the predetermined pressure value If the applied vehicle deceleration is at least equal to said limit value, said piston is When moving at the predetermined pressure value, the deceleration responsive member acts to push the valve body in a fixed position, thereby causing the valve body to A brake pressure reducing valve assembly characterized in that a material is capable of engaging the valve seat. body. 5. 5. The brake pressure reducing valve assembly according to claim 4, wherein the predetermined pressure value If the applied vehicle deceleration is less than or equal to said limit value, then the piston will increase to said predetermined pressure. When moving at a force value, the deceleration responsive member causes the valve member to allowing the valve member to move with the valve seat, thereby separating the valve member from the valve seat. A brake pressure reducing valve assembly characterized in that the brake pressure reducing valve assembly is maintained in a state in which the brake pressure is reduced. 6. 6. The brake pressure valve assembly of claim 5, wherein said deceleration responsive member is connected to said brake pressure valve assembly. positioned within the cage-like portion of the valve body and seated on the slope of the valve body. A brake pressure reducing valve assembly characterized in that: 7. A brake pressure reducing valve assembly according to any one of claims 1 to 6, comprising: The deceleration response member has a slope extending from the axis of motion of the piston toward the rear of the vehicle. when the deceleration responsive member is transferred to the rear of the vehicle when in use; The deceleration responsive member is seated when no fluid pressure is present within the valve body. A brake characterized in that it is seated on a slope that is steeper than the slope of the road. Pressure reducing valve assembly. 8. The brake pressure reducing valve assembly according to any one of claims 2 to 7, A block characterized in that the valve notation member is constituted by a part of the deceleration response member. Rake pressure reducing valve assembly. 9. A brake pressure reducing valve assembly according to any one of claims 1 to 8, comprising: responsive to an increase in pressure in the inlet chamber after the normally open valve means is occluded; so as to increase the pressure in the outlet chamber to a lesser extent. A brake pressure reducing valve assembly characterized in that: 10. A brake pressure reducing valve assembly according to any one of claims 1 to 9, the deceleration responsive member is positioned out of the flow path of fluid flowing through the pressure reducing valve assembly; A brake pressure reducing valve assembly characterized in that: