JPH0627485Y2 - Velocity control valve for vehicle brake fluid pressure retention device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake fluid pressure retaining device, and more particularly, to a brake fluid flow when releasing the fluid pressure retaining operation. The present invention relates to improvement of a brake fluid pressure retaining device having a flow rate adjusting valve. BACKGROUND OF THE INVENTION [0002] In a general vehicle driving operation, a vehicle stopped by a braking operation keeps a braking force by continuously depressing a brake pedal or depressing a brake pedal. Either release it and leave it, or operate the parking brake device to maintain a reliable stopped state, as is often done on slopes, etc., depending on the situation at that time, driver's habit etc. It is usually done selectively in. However, it is not preferable that the stopped vehicle suddenly moves. Therefore, it is generally desirable to operate the above-mentioned parking brake device or continue to depress the brake pedal. However, such an operation is complicated, and the parking brake is often not used except on a slope, so that the stopped vehicle may be in a state where no braking is applied, which may cause an unexpected movement. There is also. Therefore, after the vehicle is stopped by performing the brake operation, and until the next operation such as engaging the clutch and starting the vehicle is performed, mechanically and automatically the wheel cylinder fluid pressure ( For the purpose of holding (brake hydraulic pressure), for example, an electromagnetically actuated hydraulic pressure holding valve is provided in a hydraulic pressure path connecting an input device such as a master cylinder to a wheel cylinder.
A structure has been developed in which the brake fluid pressure in the wheel cylinder is maintained and maintained between the vehicle stop operation (brake operation) and the next vehicle start operation, which basically has the following configuration. It is a thing. That is, in a brake hydraulic pressure transmission system of a vehicle, an input hydraulic chamber on the master cylinder side, an output hydraulic chamber on the brake device side, and a normally open hydraulic pressure holding valve capable of opening and closing communication between them, and this hydraulic pressure. An electromagnetic actuating mechanism that shifts the holding valve to a closed state by movement by an electromagnetic force of an amateur, and switches and maintains the hydraulic pressure holding valve in the closed state by the operation of the electromagnetic actuating mechanism when the traveling vehicle is stopped. It is a composition. By the way, it has been recognized that the brake hydraulic pressure transmission system having such a hydraulic pressure holding valve (hereinafter referred to as an auto stop valve) has the following points to be improved in actual use. In other words, the hydraulic pressure that was contained in the brake device and prevented from returning,
Considering the state of returning to an input device such as a master cylinder (hereinafter abbreviated as a master cylinder) at the next vehicle start, this is because the brake is released as a result of releasing the state where the auto stop valve electromagnetically closes the path. The high hydraulic pressure in the device is instantaneously transmitted to the master cylinder, which often causes the piston in the master cylinder to return to its original position due to an impact, giving a large load to the input device due to vibration, etc., or It may cause an abnormal noise and may give an unexpected shock to the driver. This problem is particularly noticeable when a high brake fluid pressure is contained. Therefore, in order to suppress such a sudden return of the brake pressure fluid, it has been proposed to provide a flow rate adjusting valve in the middle of the piping of the transmission system. By the way, considering the brake system of the vehicle as a whole, it is desired that the flow velocity adjusting valve satisfies two contradictory functions. In other words, considering the braking operation in two cases, that is, during traveling and when it is completely stopped, in the former case, it is preferable that the brake fluid pressure is quickly returned when the braking operation is stopped.
In the latter case, it is preferable that the return speed of the brake hydraulic pressure be sufficiently suppressed in relation to the operation of the hydraulic pressure holding valve as described above. In order to satisfy each of these contradictory requirements, for example, the degree of flow velocity suppression of the flow velocity adjusting valve is
It is considered to set it in the intermediate range of both functions. SUMMARY OF THE INVENTION An object of the present invention is to provide a brake system in view of the fact that the request for the return speed of the brake fluid pressure differs depending on the situation of the vehicle being running or stopped. To provide a vehicle brake hydraulic pressure retaining device including a flow rate adjusting valve that mechanically optimizes the hydraulic fluid return speed by utilizing the fact that the pressure states in the path are not the same between the situations. It is in. Therefore, the gist of the present invention for achieving the above object is that the brake pressure fluid in the downstream brake device returns to the upstream input device side from the time the vehicle is stopped until the next start. In the vehicle brake hydraulic pressure holding device, which is provided with a hydraulic pressure holding valve for preventing the above, so as to hold the brake hydraulic pressure in the brake device, in the path between the hydraulic pressure holding valve and the input device, A flow rate adjusting valve that suppresses the returning speed of the brake pressure liquid is provided, and the flow rate adjusting valve has a communication relationship in which the first liquid chamber, the second liquid chamber, and the third liquid chamber are sequentially connected in this order from the upstream side. An orifice piston having a liquid chamber, the upstream end of which faces the first liquid chamber and the downstream end of which faces the second liquid chamber, and the upstream end of which faces the second liquid chamber and the downstream end of which faces the third liquid chamber. Abut against the orifice piston A pressure reducing piston, spring means for biasing the pressure reducing piston to the initial position on the upstream side in a state of abutting the orifice piston by pressing the pressure reducing piston to the upstream side, and the spring means provided outside the pressure reducing piston. A pressure reducing chamber that is provided so as to be able to communicate with the two liquid chambers, and a facing contact surface between the orifice piston and the pressure reducing piston. When the pistons are in contact with each other, the second liquid chamber and the pressure reducing chamber are liquid tight. The first decompression chamber and the first decompression chamber, which are shut off from each other but communicate with each other when these pistons are separated from each other
And a one-way sealing means for connecting between the liquid chambers so as to allow only the pressure liquid to flow from the decompression chamber toward the first liquid chamber, wherein the orifice piston has a first position when the initial position is set.
It has an orifice passage that suppresses the returning speed of the brake pressure fluid from the fluid chamber to the upstream flow passage, the pressure receiving area of the orifice piston with respect to the first fluid chamber is A ₁ , and these pistons are in contact with each other. The pressure receiving area for the second liquid chamber of A ₂ is A ₂ , the pressure receiving area of the pressure reducing piston for the third liquid chamber is A ₃ , and these pressure receiving areas have a relationship of A ₁ > A ₂ > A _3. It is on the flow rate control valve for the brake fluid pressure retention device. According to such a device, during normal braking, since the hydraulic pressure is transmitted from the input device to the liquid chamber (first liquid chamber) provided on the upstream side of the orifice piston, the orifice piston moves. Then, the orifice passage for returning the brake pressure liquid is expanded to realize a quick flow of the pressure liquid, and when releasing the brake in this state, the hydraulic pressure in the brake device can be quickly reduced. On the other hand, when the hydraulic pressure holding valve is operating when the vehicle is stopped, since the flow velocity adjusting valve is on the upstream side of the hydraulic pressure holding valve, it returns to the initial position and returns the pressure liquid by the orifice piston. The passage is limited to only the orifice passage, and when the hydraulic pressure holding valve is released in this state, the orifice piston does not move but only the pressure reducing piston moves, and the liquid chamber (the liquid chamber located between the orifice piston and the pressure reducing piston ( Although the internal volume of the second liquid chamber) is increased, and this rapidly reduces the hydraulic pressure in the brake device,
The return of the pressure fluid to the input device side is limited to the orifice passage and is performed gently. As a result, a preferable return of the pressure fluid can be achieved in accordance with the brake release while the vehicle is traveling and the brake release when the vehicle is stopped. Embodiments of the Invention and Effects thereof The present invention will be described based on the embodiments shown in the drawings. FIG. 1 shows an example of a flow rate control valve according to the present invention. The upper part of the drawing is connected to the master cylinder side which is an input device, and the lower part of the drawing is connected to the brake device side. A pressure holding valve (not shown) is connected on the downstream side. In the figure, reference numeral 1 denotes a hollow valve body, a port 2 is provided on the upstream side of the valve body 1, and a plug 3 is attached on the downstream side. Reference numeral 4 denotes an orifice piston formed to have large and small diameter steps, the small diameter portion is located on the upstream side, and the end face of the small diameter step portion is seated on the valve seat 1'of the valve body 1. It is like this. An orifice passage 5 that communicates with the port 2 in the state where the small diameter portion is seated on the valve seat 1'of the valve body 1 is provided in the end surface of the small diameter portion of the orifice piston 4 in the radial direction. The liquid flow between the first liquid chambers 6 facing the end surface of the small diameter portion is restricted. Further, the orifice piston 4 has the first liquid chamber 6
And liquid passages 7 and 8 for communicating with a second liquid chamber 14 described later. Reference numeral 9 denotes a seal groove on the outer circumference of the orifice piston 4, which is fitted with the piston cup 10 to allow the flow of the pressure liquid from the decompression chamber 14 'to be described later in the first liquid chamber direction, but to prevent the pressure liquid from flowing in the opposite direction. Distribution is not allowed. Normally, the second liquid chamber 14 and the decompression chamber 14 'are not communicated with each other, and the orifice piston 4 and the decompression piston 11 (described later) engaged with the orifice piston 4 are communicated with each other when they are separated from each other. I am doing it. Note that this point will be described later. Reference numeral 11 denotes a decompression piston, which is formed stepwise in the present embodiment, the large-diameter end portion side of which faces the large-diameter end portion of the orifice piston 4, and the hold spring 12 with a light load holds the orifice piston 4. 4 and the pressure reducing piston 11. A liquid passage 13 for communicating the second liquid chamber 14 with the third liquid chamber 21 facing the small-diameter end of the pressure reducing piston 11 is bored in the central portion of the shaft of the pressure reducing piston 11. ing. A relief seal 15 is attached to the central portion of the end surface of the large-diameter portion of the decompression piston 11, and when the relief seal 15 and the orifice piston 4 are brought into contact with each other by the spring force of a set spring 17, which will be described later, It functions to block communication between the chamber 14 and the decompression chamber 14 '. Reference numeral 16 denotes a reservoir piston formed with large and small diameter stepped outer diameters, and the large diameter portion is located on the upstream side and is mounted on the small diameter portion of the pressure reducing piston 11 and the tip portion of the plug 3. At the same time, it is biased in the upstream direction by a set spring 17 having a high load (F ₁ ) by a hold spring 12, and this reservoir piston 16 causes the orifice piston 4 to be seated on the valve seat 1 ′ via the pressure reducing piston 11. ing. Reference numerals 18, 19 and 20 denote oil seals attached to the pressure reducing piston 11, the reservoir piston 16 and the plug 3, respectively. In the above structure, the flow rate control valve of this example has the following structure for achieving the above-mentioned object.
The dimensions of each part are set as follows. That is, the flow surface cross-sectional area of the orifice passage 5 is sufficiently smaller than the flow passage cross-sectional area of the relief port of the master cylinder, which is an input device (not shown).
It is set to about 2 to suppress the flow velocity when returning the pressurized liquid. Further, as shown in FIG. ₁ , the pressure receiving area of the orifice piston 4 with respect to the first liquid chamber 6 is A ₁ , and the second liquid of these pistons 4 and 11 when these pistons 4 and 11 are in contact with each other. The pressure receiving area for the chamber 14 is A ₂ , and the pressure receiving area for the third liquid chamber of the decompression piston 11 is A ₃ , and these pressure receiving areas are set to have a relationship of A ₁ > A ₂ > A ₃ . Next, the function of the flow rate adjusting valve having such a structure will be described with reference to FIGS. 1 to 4. When the brake fluid pressure is transmitted from the master cylinder from above in the figure by the brake operation, the brake fluid flows into the first fluid chamber 6 through the orifice passage 5 and acts on the orifice piston 4. Next, when the hydraulic pressure P becomes the following expression (1), as shown in FIG. 2, the set spring 17 is compressed while the orifice piston 4, the pressure reducing piston 11 and the reservoir piston 16 are in mutual contact, and the pressure reducing piston 11 It moves in the downstream direction until it comes into contact with the plug 3. [Formula 1] Then, a large amount of brake fluid flows from the master cylinder to the fluid passage 7 without being affected by the throttling effect of the orifice passage 5.
The liquid passes through the liquid passages 13 in that order and is immediately transmitted to the brake device side (the lower side in the figure). At that time, since the relief seal 15 is provided on the abutting surface of the orifice piston 4 and the pressure reducing piston 11, the hydraulic pressure for pushing the orifice piston 4 upward in the figure becomes PA ₂ (<PA ₁ ) and the orifice The piston 4 will be held in the state shown in FIG. When the vehicle is stopped in this state and a hydraulic pressure holding valve (not shown) is activated to reduce the hydraulic pressure in the master cylinder by releasing the brake, the hydraulic pressure in the flow velocity adjusting valve is reduced, as shown in FIG. With the orifice piston 4, the decompression piston 11, and the reservoir piston 16 engaged with each other, they are returned to the initial position (the position shown in FIG. 1) by the spring force of the set spring 17 (see FIG. 3). In this state, the master cylinder and the brake device side are in communication with each other through the orifice passage 5, so that the throttle effect by the orifice passage 5 can be obtained at the time of the next pressure liquid return. Next, when the operation of the hydraulic pressure holding valve is released, the brake fluid is rapidly supplied from the brake device side to the third fluid chamber 2
1, and further flows into the second liquid chamber 14. When the hydraulic pressure P ₂ in the second liquid chamber 14 has the relation of the following equation (2),
As shown in the figure, the decompression piston 11 and the reservoir piston 16 are pushed downward against the spring force of the set spring 17 with the orifice piston 4 seated on the valve seat 1 '. [Equation 2] At that time, since the brake fluid pressure pushes the orifice piston 4 from the downstream side to the upstream side, the orifice piston 4 is kept seated on the valve seat 1 ',
On the other hand, the hydraulic pressure P ₂ moves the pressure reducing piston 11 to the downstream side. Therefore, the orifice piston 4 and the pressure reducing piston 11 are separated from each other, the second liquid chamber 14 and the pressure reducing chamber 14 'are communicated with each other, and the hydraulic pressure on the brake device side is rapidly reduced. When the hydraulic pressure holding valve is released in this way, the brake fluid pressure returning from the brake device side to the master cylinder side is reduced by the pressure of the following formula (3), and the brake fluid returning to the master cylinder is It will be throttled by the orifice path 5. At that time, since the flow passage area of the orifice passage 5 is smaller than the flow passage area of the relief port of the master cylinder, the brake fluid is gently returned into the master cylinder. [Equation 3] From this, when the hydraulic pressure holding valve is released, the hydraulic pressure and flow velocity of the brake fluid returning from the brake device side to the master cylinder side are reduced, so that the input equipment such as the master cylinder is adversely affected by vibrations and the like. It does not extend. When the hydraulic pressure P _{2 of the} brake fluid returning from the brake device side to the master cylinder is reduced to the relationship of the following formula (4), the pressure reducing piston 11 and the reservoir piston 16 are moved by the set spring 17 to The brake fluid that has been pushed upward and that has flowed into the decompression chamber 14 ′ is returned to the first fluid chamber 6 through the space between the orifice piston 4 and the valve body 1, and the decompression piston 11 engages with the orifice piston 4. As shown in FIG. 1, the brake fluid pressure on the brake device side is further reduced to zero. [Equation 4] By the way, when the hydraulic pressure holding valve does not operate (when the brake is released while the vehicle is traveling), when the brake pedal is released after the brake is operated, the hydraulic pressure in the flow velocity adjusting valve is reduced to the following equation (5). since the depressurized smoothly, in the present embodiment the value of the expression (5) about 2kgf / cm ² ~5kgf / cm ²
The degree is set so that braking is not affected. [Equation 5] Needless to say, the embodiments of the present invention are not limited to the above, but various modified embodiments can be considered. In short, a flow rate adjusting valve and a hydraulic pressure holding valve are arranged in series in the path between the input device and the brake device, and shocking pressure fluid return that may occur when the hydraulic pressure holding valve is released. On the other hand, the hydraulic pressure in the brake device may be smoothly reduced without being affected by the return limitation of the hydraulic fluid by the orifice path or the like. A flow path restriction mechanism that operates when the hydraulic pressure retention valve is activated during stoppage and does not operate at other times, and brake hydraulic pressure temporarily flows in downstream of this flow path restriction mechanism, causing a sudden increase in brake hydraulic pressure. It is sufficient to have a decompression mechanism that realizes decompression. As the hydraulic pressure holding valve, a known one can be used, so the illustration is omitted. As described above, the brake pressure holding device according to the present invention suitably eliminates the difficulties caused in the practical implementation of this type of device, and the actual benefits thereof are great.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an operating state of an embodiment of a flow rate control valve according to the present invention. FIG. 2 is a sectional view showing an operating state of an embodiment of a flow rate adjusting valve according to the present invention. FIG. 3 is a sectional view showing an operating state of an embodiment of a flow rate control valve according to the present invention. FIG. 4 is a sectional view showing an operating state of an embodiment of a flow rate adjusting valve according to the present invention. [Explanation of Codes] 1 ... Valve body 2 ... Port 3 ... Plug 4 ... Orifice piston 5 ... Orifice passage 6 ... First liquid chamber 7 ... Liquid passage 8 ... Liquid passage 9 ... Seal groove 10 ... Piston cup 11 ... Decompression piston 12 ... Hold spring 13 ... Liquid passage 14 ... Second liquid chamber 15 ... Relief seal 16 ... Reservoir piston 17 ... Set springs 18, 19, 20 ... Oil seal 21 ... Third liquid chamber

Claims (1)

[Claims for utility model registration] [1] Between the time the vehicle is stopped and the next start, a hydraulic pressure holding valve that prevents the brake pressure liquid in the downstream brake device from returning to the upstream input device side is provided in the middle of the path. In a vehicle brake fluid pressure holding device for holding the brake fluid pressure in the brake device, a flow rate adjustment for suppressing the return speed of the brake fluid pressure is provided in the path between the fluid pressure holding valve and the input device. A valve is provided, and this flow rate adjusting valve is provided with a liquid chamber such that the first liquid chamber 6, the second liquid chamber 14, and the third liquid chamber 21 have a sequential communication relationship from the upstream side in order. The orifice piston 4 whose upstream end side faces the first liquid chamber 6 and whose downstream end side faces the second liquid chamber 14, and the upstream end side which is the second
The pressure-reducing piston 1 which faces the liquid chamber 14 and whose downstream end faces the third liquid chamber 21 and abuts and abuts against the orifice piston 4.
1 and the spring means 12 that biases the pressure reducing piston 11 to the initial position on the upstream side in a state of abutting the orifice piston 4 by pressing the pressure reducing piston 11 to the upstream side.
And provided on the outside of the decompression piston 11, the second
The pressure reducing chamber 14 ′ that is provided so as to be able to communicate with the liquid chamber 14 and the facing contact surface between the orifice piston 4 and the pressure reducing piston 11 are provided. When the pistons 4 and 11 contact each other, the second liquid chamber 14 is provided. And the decompression chamber 14 ′ are liquid-tightly shut off, but the sealing means 15 for communicating when the pistons 4 and 11 are separated from each other, the decompression chamber 14 ′ and the first liquid chamber 6
Between the pressure reducing chamber 14 ′ and the first liquid chamber 6 so as to allow only the pressure liquid to flow therethrough, and the orifice piston 4 has a first position when it is in the initial position. The orifice passage 5 for suppressing the returning speed of the brake pressure liquid from the liquid chamber 6 to the upstream flow passage is provided, and the pressure receiving area of the orifice piston 4 with respect to the first liquid chamber 6 is A ₁ . The pressure receiving area of these pistons 4 and 11 against the second liquid chamber 14 at the time of contact is A ₂ ,
The pressure receiving area of the pressure reducing piston 11 with respect to the third liquid chamber 21 is A
_3. A flow velocity adjusting valve for a vehicle brake hydraulic pressure holding device, wherein the pressure receiving areas of these are set as A ₁ > A ₂ > A ₃ .