JPS6045459A - Brake valve and hysteresis reducing method therein - Google Patents

Abstract

PURPOSE:To absorb the performance hysteresis of brake valve by transmitting the pedal stepping force through a coil spring to the piston upon stepping of brake while producing the sliding resistance against the piston through a sliding member upon releasing of brake. CONSTITUTION:Upon stepping of a brake pedal 10, a piston 11 will move downward through a plunger 21, press member 27, coil spring 28, etc. to block communication between a central exhaust path 68 and an output chamber 33. Then a supply/discharge valve member 64 will depart from a valve seat 66 to feed air provided through a feeding port 14 into the output chamber 33 to the braking machineries in the primary system through the port 15 then through the port 17 to the braking machineries in the secondary system. Upon release of pedal 10, the piston 11 is moved upward by the air pressure in the output chamber 33 and a return spring 40, but it will receive frictional sliding resistance from a sliding ring 35 to absorb the performance hysteresis of brake valve.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technique for reducing hysteresis in brake characteristics in a brake valve used in a vehicle brake system.

Conventionally, in this type of brake valve, the pedal force applied to the brake pedal is transmitted to the piston via a spring.
The supply/discharge valve operates in response to the movement of the piston, and controls communication between the supply port that receives air from the fluid pressure source and the output port that outputs air to the brake operating device. As the spring located between the brake pedal and the piston, either a coil spring or a rubber spring is used.

By the way, the inventor's studies have revealed that there are advantages and disadvantages when using either a coil spring or a rubber spring.

First, when considering the spring alone, a coil spring inherently has almost no hysteresis in its strain-stress characteristics, whereas a rubber spring has a considerable amount of hysteresis in that respect. In the case of rubber springs, hysteresis varies depending on the amount of strain, but for example, at the same strain,
The stress value is about 10 kg smaller when the pressure is removed than when the pressure is applied.

However, apart from that, the brake valve assembly itself has hysteresis in the performance of the discharge pressure with respect to the pedal depression force. The hysteresis is caused by the self-sealing force that is constantly applied to the supply and discharge valves. Self-sealing force is to prevent the compressed air in the main tank from leaking from the discharge port when the brake valve is inactive, and is obtained as the sum of the valve spring force and the air pressure applied to the differential area, for example. It is about 10 kg in size.

Therefore, when considering the brake valve as a whole, 3- In the case where a rubber spring is disposed between the brake pedal and the piston, the performance hysteresis of the brake valve is offset by the hysteresis of the strain-stress characteristics of the rubber spring. It has the advantage of being absorbed. However, since the rubber spring is made of rubber, it is difficult to compare due to heat, a set load that is constantly applied (this load is large, for example, about 30 kg), or a load that is repeatedly applied. This has the disadvantage that the brake valve deteriorates or settles prematurely, which makes the performance characteristics of the brake valve unstable.

On the other hand, a coil spring placed between the brake pedal and the piston has the advantage of good spring durability and excellent load stability. Since the brake valve assembly has no hysteresis, it has the disadvantage that it cannot absorb the performance hysteresis of the brake valve assembly.

This invention was made in consideration of the above points, and 4- The purpose is to use a coil spring with excellent durability and stability, while solving the disadvantage of hysteresis when using a coil spring. The purpose is to eliminate this problem by providing resistance based on frictional force when the piston returns.

Other objects and novel features of the invention will become apparent from the description of this specification and the accompanying drawings.

This invention is characterized by a method for reducing hysteresis in brake characteristics and a brake valve based on the method, but since the method will become clear by explaining the brake valve itself, the explanation will focus on the brake valve here. .

Hereinafter, the content of the present invention will be made clear by describing embodiments shown in the accompanying drawings.

FIG. 1 is a sectional view showing the overall structure of a two-system brake valve according to an embodiment of the present invention.

A valve body 2 forms the housing of the two-system brake valve 1. The valve body 2 includes a main body part 5 having a first cylinder hole 3 and a second cylinder hole 4 in the vertical direction, and an upper member 7 and a lower member 8 fixed to the upper and lower parts of the main body part 5 by bolts 6 or the like, respectively. Consisting of In this case, a seal ring 9 is interposed between the internally hollow main body portion 5 and the lower member 8 to keep the joint portion airtight. However, the upper member 7
No seal ring is used for installation. A first piston 1 driven by a brake pedal 10
This is because the upper chamber 12 is a chamber that communicates with the atmosphere. Communication to the atmosphere is provided through holes provided in the sliding surface of the sliding ring 25 and the boot 26, which will be described later.

In addition, since the upper member 7 also serves as a plate for mounting the brake valve 1 itself, a port 1 through hole 13 is provided on the outer periphery. Further, a supply port 14 and an output port 15 of the primary part are provided on the upper side of the main body portion 5 of the valve body 2.
A supply port 16 and an output port 17 of the secondary section are provided below.

The brake pedal 10 located above is rotatably supported around a pin 18 supported by the upper member 7, and a central plunger is supported by a roller 20 fitted on a shaft 19 located a little distance from the pin 18. 21- can be pushed downward. The plunger 21- is composed of a head plate 22 in contact with the roller 20 and a cup-shaped main body 23, and the main body 23 is fitted into a hole 24 passing through the center of the upper member 7 via a sliding ring 25 made of sintered metal. It is crowded.

For this purpose, a boot 26 is set around the plunger body 23 and covers the hole 24 from above. The lower end of the plunger 21- reaches inside the valve body 2 and can drive the first piston 1-1 of the primary portion via the pressing member 27 and the coil springs 28, 29. Here, among the coil springs 28 and 29, the outer circumference side coil spring 28 uses the pressing member 27 as an upper spring receiver, so even if the depression angle of the brake pedal 1-0 is small, the depression force causes the first piston 11
can always be driven. However, since the other inner coil spring 29 uses a separate spring receiver 30 placed a predetermined distance vertically between it and the pressing member 27 as an upper spring receiver, the suppressing member 27 is lowered. The first piston 11 can be driven only after the bottom surface of the piston contacts the spring receiver 30, that is, only within a range where the depression angle is equal to or greater than a certain value. Since such two coil springs 28 and 29 are used, the air pressure contributing to brake operation can be rapidly increased after a predetermined depression angle.

The first piston 11 is slidably inserted into the first sill hole 3 inside the valve body 2 with a bushing 31 interposed therebetween.
The lower side is isolated from the atmosphere by a seal ring 32 on the outer periphery, and a first output chamber 33 is formed below the piston. This first output chamber 33 communicates with the output port 15,
It is connected through the output port 15 to a primary brake operating device, such as a relay valve or a brake chamber (not shown). Although the bushing 31 is used to make the valve body 2 common to multiple types of brake valves, the bushing 31 may be omitted by changing the design of the valve body 2 itself.

8- Now, the suppressing member 27 arranged in the recess on the inner circumference of the first piston 11 is connected to the coil spring 28 as described above.
Although it forms an upper spring receiver, it is not only the case that the first piston 1.1. It also constitutes one component of the return resistance applying mechanism 34 for providing resistance based on frictional force. This return resistance imparting mechanism 34 is important in eliminating hysteresis in brake characteristics (this point will become clear from the explanation given later). A spring 36 that constantly presses the ring member 35 and the sliding ring member 35 downward.
It is made up of. The details of the return resistance applying mechanism 34 are clarified in the enlarged view of the main part shown in FIG. As shown in FIG. 2, the first piston 11 has a guide portion 1 on the inner circumference side that guides the outer circumference of the suppressing member 27.
11 is also provided, but the upper side of the guide portion 11.1- is set larger than the outer diameter of the pressing member 27, and there is a gap between the outer periphery of the pressing member 27 and the inner periphery of the first piston 11. A gap 37 is provided therein.

In this gap 37, the inner circumferential side of the first piston 1-1 is parallel to the axial direction (vertical direction) of the piston 11 and the pressing member 27, while the outer circumferential side of the pressing member 27 has an upward direction. A slope 271 is provided that becomes smaller in diameter toward the surface. The rubber sliding ring member 35 is set on the outer periphery of such a slope 271 portion.

The sliding ring member 35 has a wedge-shaped cross section, and has a sliding surface 350 on the outer circumferential side that can slide along the inner circumferential surface of the first piston 11, and has a sliding surface 350 on the inner circumferential side that is slidable along the inner circumferential surface of the first piston 11. It has a slope 351 corresponding to the slope 271. A spring 36 is connected to such a sliding ring member 35 via a spring receiver 38.
Since the urging force is constantly applied, the slope 351 of the sliding ring member 35 is in contact with the slope 271 of the pressing member 27.

The other spring receiver 39 of the spring 36 is attached to the upper outer periphery of the pressing member 27. Note that it is the return spring 40 on the lower surface side of the first piston 11 that applies a return force to the first piston 11. When the brake is released, the first piston 1-1 is pushed up to one side by the return spring 40 and maintained in the relaxed state shown in the figure. The position of the brake pedal 10 in the relaxed state is controlled by an adjustment screw 41 provided at one end of the pedal 10. It is carried out by

By the way, in the center of the first piston 1-1, there is a cylindrical portion 42 that extends upward. This cylindrical portion 42 is a portion that supports the spring receiver 30 and the pressing member 27, and is also a portion that supports the lifting mechanism. The lifting mechanism is mainly composed of a lifting spring 43;
and for lifting and supporting the second piston 45 via the stem 44. The second piston 45 has
There is a cylindrical portion 46 extending vertically in the center thereof, and this cylindrical portion 4
The upper end of the piston 6 fits into the cylindrical portion 42 of the first piston 11, and is fixed to the large diameter portion 441 at the lower end of the stem 44 by a step on the inner circumferential side thereof.

A sleeve 84 is fitted into the inner periphery of the cylindrical portion 42 of the first piston 1-1-, and one end of the sleeve 84 passes through the cylindrical portion 11-42 and is fixed onto the suppressing member 27 by a nut 47. ing. The stem 44 is then inserted into such sleeve 84. Lower end 4 of stem 44
41 has a larger diameter than the other parts, so it hits a stepped part in the middle of the cylindrical part and is stopped from moving upward. On the other hand, the upper end part 442, which has a smaller diameter, is larger than the cylindrical part 46 of the second piston 45. It's jumping out. The lifting spring 43 includes a spring receiver 49 fixed to the upper end portion 442 of the stem by a C ring 48, and a spring receiver 50 placed on the upper part of the pressing member 27.
It is set between.

The main body portion of the second piston 45 is inserted into the second cylinder hole 4, and a seal ring 51- is set on its outer periphery to airtightly seal the upper chamber 52 and the lower chamber 53. ing. The upper chamber 52 of the second piston 45 communicates with the first output chamber 33 of the primary part through a through hole 54 provided in the main body part 5. Therefore, the driving force for the second piston 45 is obtained by the air pressure from the first output chamber 33. On the other hand, the second piston 4512
- The lower chamber 53 constitutes a second output chamber, which is connected through the output ports 1 to 17 to a secondary brake actuation device, such as a relay valve or a brake chamber (also not shown). ). Note that a piston spring 55 is set within the upper chamber 52, and applies a downward biasing force to the second piston 45.

This piston spring 55 is for reducing the pressure difference between the first output chamber 33 of the primary section and the second output chamber 53 of the secondary section.

Next, the relationship between the supply and exhaust valves that control air supply and exhaust will be described. Two supply/discharge valves are provided, a first and a second, corresponding to the primary part and the secondary part. These first and second supply/discharge valves 56 and 57 are located at the upper and lower portions of the second piston 45, respectively. First supply/discharge valve 5 located on the upper side
6 is a valve chamber 58 provided below the first cylinder hole 3
is housed within. On the other hand, the second supply/discharge valve 57 located on the lower side is accommodated in a valve chamber 59 provided in the lower member 8.

The valve chamber 58 of the primary portion is airtightly partitioned from the upper chamber 52 of the second piston 45 by a partition member 62 having seal rings 60 and 61 attached to the inner and outer peripheries.
It is connected to a primary system fluid pressure source (not shown) through supply boats 1-4. Such a valve chamber 5
8, a first supply/discharge valve member 64 biased upward by a valve spring 63 is arranged between an exhaust valve seat 65 provided at the lower end of the first piston 11 and a supply valve seat 66 provided on the valve body 2. arranged so as to be able to engage with. Therefore, the supply/discharge valve member 64 and the supply valve seat 66 are used to connect and disconnect the supply boat 14 and the first output chamber 33, and the supply/discharge valve member 64 and the exhaust valve seat 65 are used to provide the output. The chamber 33 is connected to the second piston 45
A through hole 67 in the cylindrical portion 46, an exhaust passage 6 on the inner circumference of the cylindrical portion 46
8 and the exhaust port 7 through an exhaust passage 70 provided in a second supply/discharge valve member 69 similar to the first supply/discharge valve member 64.
1- constitutes an exhaust valve connected to the atmosphere.

Then, the first supply/discharge valve 56 is operated by the supply valve and the exhaust valve.
It consists of Note that the cylindrical first supply/discharge valve member 64
is fitted into the outer periphery of the cylindrical portion 46 of the second piston 45, and a seal ring 72 is provided on the sliding portion of both. Further, the partition member 62 is connected to the C
It is supported by a ring 74.

On the other hand, the valve chamber 59 of the secondary section is separated from the discharge port 71 by a partition member 77 whose inner and outer circumferences are sealed with seal rings 75 and 76, and is connected to a fluid pressure source (not shown) of the secondary system through the supply boat 16. )
is connected to. In such a valve chamber 59, a second supply/discharge valve member 69 is biased upward by a valve spring 78.
is arranged so as to be able to engage with an exhaust valve seat 79 provided at the lower end of the second piston 45 and a supply valve seat 8o provided on the lower member 8. Therefore, the supply/discharge valve member 69 and the supply valve seat 80 connect the supply valve which connects and disconnects the communication between the supply boat 16 and the second outlet chamber 53, and the supply/discharge valve member 69 and the exhaust valve seat 79 operate the supply valve. An exhaust valve connects the second outlet chamber 53 to the exhaust port 71 through the exhaust passage 70, and this supply valve and the exhaust valve constitute a 15-second supply valve 57. In addition, the discharge port 7
A support plate 82 having an opening 81 is provided below the support plate 1 , and a nitrogen seast check valve 83 is attached to the support plate 82 .

Next, regarding the action of the two-system brake valve 1 described above,
Explain briefly.

When the brake pedal 10 is depressed, the pedal force is transmitted to the first piston 11 via the plunger 21, the suppression member 27, and the coil spring 28 (or the coil springs 28 and 29 when the depression angle is equal to or greater than a predetermined value). The piston 11 compresses the return spring 40 and moves downward.

Along with this, the exhaust valve seat 65 at the lower end of the first piston 11
is in contact with the first supply/discharge valve member 64 of the primary portion, and communication between the central exhaust passage 68 and the first output chamber 33 is closed.

Further, the first piston 11 compresses the primary return spring 40, and when the first supply/discharge valve member 64 leaves the supply valve seat 66, the air pressure supplied from the supply boat 14 to the first output chamber 33 is reduced. flows out from the primary section output boat = 16-15 and is supplied to the brake operating equipment of the primary system as an instruction pressure or operating pressure. On the other hand, a part of the air pressure supplied to the first output chamber 33 is supplied to the upper part of the second piston 45 of the secondary part through the through hole 54,
Move the second piston 45 downward. Then, the exhaust valve seat 79 at the lower end of the second piston 45 comes into contact with the upper surface of the second supply/discharge valve member 69 in the secondary section, and the central exhaust passage 70
The communication between this and the second output chamber 53 is closed. Furthermore, when the second supply/discharge valve member 69 is pushed downward, the supply/discharge valve member 69 separates from the supply valve seat 80, and the air pressure from the secondary section supply boat 16 flows out from the output port 17, and the indicated pressure Alternatively, it is supplied as operating pressure to secondary brake operating equipment.

When applying the brake, the return resistance applying mechanism 3
4 exerts almost no force on the first piston 11-. This is due to the sliding ring member 35 interposed between the inner circumferential surface of the first piston 11 and the outer circumferential surface of the suppressing member 27.
This is because the cross-sectional shape of the piston 11- is wedge-shaped so that it gradually becomes smaller along the direction in which the piston 11- moves when the brake pedal 10 is depressed. Note that when the air pressure becomes stable, the first piston 11 moves slightly upward;
In that case, since the suppressing member 27 does not move, the return resistance applying mechanism 34 does not apply force to the first piston 11.

The return resistance applying mechanism 34 applies resistance based on frictional force to the first piston 11 only when the brake is released. When the pedal force applied to the brake pedal 10 is removed to release the brake, the first piston 1 is moved upward by the air pressure in the first output chamber 33 and the biasing force of the return spring 40. Then, the first piston 1
The exhaust valve seat 65 at the lower end is separated from the first supply/discharge valve member 64, and the central exhaust passage 68, 70 is opened. Therefore, the air pressure in the primary system is
and is discharged from the lower discharge port 71. When the air pressure of the primary system decreases, the air pressure of the second output chamber 53 of the secondary system communicated through the through hole 54 is also exhausted. Therefore, by the action of the supply/discharge valve of the secondary system, exhaust is performed in the same way as in the case of the primary system.

When the brake is released, the first piston 1-1 that moves upward receives additional sliding resistance based on frictional force from the sliding ring member 35 of the return resistance applying mechanism 34. This sliding resistance is caused by the coefficient of friction between the inner circumferential surface of the first piston 11 and the sliding surface 350 of the sliding ring member 35, the coil spring 28 (if the pedal is pressed heavily, the coil spring 28) 29) and each slope 271 of the pressing member 27 and the sliding ring member 35
．． It can be changed by the degree of inclination of 351-. Therefore, the performance hysteresis of the brake valve caused by the self-sealing force described above can be absorbed by this sliding resistance. Note that the spring 36 ensures that the slope 351- of the sliding ring member 35 comes into contact with the slope 271 on the pressing member 27 side, thereby stabilizing the sliding resistance.

As can be understood from the above description, in this invention, when the brake is applied, the pedal depression force is transmitted to the piston via the coil spring 19-, and when the brake is released, a sliding member such as the sliding ring member 35 is used. By creating sliding resistance between the piston and the piston, most of the pedal depression force (including reaction force) is received by the durable coil spring, while the sliding resistance generated by the sliding member is Since the performance hysteresis of the brake valve is absorbed by the brake valve, it is possible to obtain a brake valve that is highly durable, has small hysteresis, and has stable performance characteristics.

In particular, when a ring-shaped sliding member is used, the contact area of the sliding ring member can be increased, so a large sliding resistance can be easily obtained, and hysteresis in braking characteristics can be almost completely eliminated. be able to. Moreover, in the case of a sliding ring member, smooth operation can be performed without causing the coil spring to collapse.

Although the present invention has been described above based on the embodiments, it goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the gist thereof. An example of the modification is as follows 20-.

(2) The return resistance applying mechanism 34 can be constituted by a tapered groove like a freewheel and a ball installed in the groove. In this case, the balls can be provided at multiple locations along the circumferential surface of the piston.

(2) The sliding ring member 35 can be made of not only an elastic material such as rubber but also a metal material, or the sliding ring member 35 can be made of a metal material, or the sliding ring member 35 can be made of an elastic material such as rubber.
It can also be placed on the outer periphery side. As in the example, the first
The one in which the sliding ring member 35 is arranged on the inner circumferential side of the piston 11 is advantageous in terms of space and allows the brake valve to be made compact; Since the contact area of the members can be made larger, a large sliding resistance can be obtained more easily.

■A sliding member such as the sliding ring member 35 can be placed on the upper surface of the first piston 11. In that case, the suppression member 27 is the other member other than the piston 11 that the sliding member contacts. In addition to this, the upper member 7 can also be used.

■The example shows an example of application to a two-system brake valve, but
This invention can also be applied to one system.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the overall structure of an embodiment of a brake valve according to the present invention, and FIG. 2 is an enlarged sectional view of the main parts in FIG. 1. 1...2-system brake valve, 2...valve body, 10...
- Brake pedal, 11... first piston, 14.
16... Supply port, 15.17... Output port,
27... Suppression member, 28.29... Coil spring, 34... Return resistance imparting mechanism, 35... Sliding ring member (sliding member), 350... Sliding surface, 351-...
...Slope, 36...Spring, 37...Gap, 40...
・Return spring, 45...Second piston, 5
6... First supply/discharge valve, 57... Second supply/discharge valve, 71
-...Exhaust port. Agent Patent Attorney Toshio Yasushina 23-

Claims (1)

[Claims] 1. A piston that is moved via a coil spring by the force applied to the brake pedal, a supply port that operates in response to the movement of the piston, and receives air supply from a fluid pressure source, and a brake operating device. In the brake valve, the brake valve includes a supply/discharge valve that controls communication with an output port that outputs air to the piston, and a return spring that applies a return force to the piston. By providing at least a portion of the gap between the two spaces, a portion that gradually becomes smaller along the direction in which the piston moves when the brake pedal is depressed, and by arranging a sliding member such as a wedge member or a ball in such a gap portion. A method for reducing hysteresis in a brake valve that provides resistance based on frictional force when the piston returns. 2. A valve body having a supply port connected to a fluid pressure source, an output port connected to a brake operating device, and an exhaust port communicating with the atmosphere, a brake pedal swingably attached to the upper part of the valve body, and the valve A piston is slidably inserted into a cylinder hole provided in the main body, and is moved via a coil spring by the pedal force applied to the brake pedal. between the output port and the discharge port 1-
In a brake valve equipped with a supply/discharge valve that controls communication between the piston and a return spring that provides a return force to the piston, the gap between the circumferential surface of the piston and a member other than the piston that faces the piston is The piston is made to gradually become smaller along the direction in which it moves when the brake pedal is depressed, and a sliding ring member having a wedge-shaped cross section is disposed in the gap, and the sliding ring member of the bracket is always held downward by a spring. Brake valve made by pressing. 3. The gap is formed between the outer circumferential surface of a pressing member that is disposed in a recess on the inner circumference of the piston and is capable of suppressing the piston via the coil spring, and the inner circumferential surface of the piston. The brake valve according to claim 2, wherein the outer circumferential surface of the suppressing member has a slope whose diameter becomes smaller toward the upper side.