JPH0425183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load sensing proportioning valve (hereinafter referred to as LSPV).

Generally, it is considered ideal that the braking force in a vehicle such as an automobile should be distributed between the front and rear wheels so that the front and rear wheels lock simultaneously, and the characteristic line thereof is called the ideal braking force distribution curve. Furthermore, it is known that this curve differs depending on the live load.

LSPV is applied to obtain a braking force distribution line that is as close as possible to the ideal braking force distribution curve depending on the live load, and usually links the relative displacement between the vehicle body and the rear axle. The brake pressure of the rear wheels is adjusted by controlling the opening and closing of a valve provided between the pressure medium inlet and outlet passages according to the amount of displacement, as shown in Fig. 4. As shown in the figure, each braking force distribution line approximates the ideal braking force distribution curve (imaginary line) according to each load. The bending points (adjustment starting points) in each braking force distribution line shown in FIG. 4 are called split points.

Conventional LSPV extracts the amount of relative change between the frame and axle that corresponds to changes in live load using a link mechanism, etc. and converts it into the amount of spring deflection, and uses this spring force to create an intervening space between the inflow and outflow paths. The differential piston that controls the opening and closing of the installed valve is constantly energized, and the operation of this piston is controlled by changes in the strength of this spring force, creating a split point that corresponds to the live load. has been done.

However, in this type of LSPV, the spring serving as a load detection means constantly biases the differential piston, so when the brake is not applied, the differential piston moves freely due to the expansion and contraction of the load detection spring as the frame moves up and down. This has the disadvantage of causing wear, failure, malfunction, etc.

One of the objects of the present invention is to provide an LSPV that can avoid free movement of the differential piston during non-braking.

Another object of the present invention is to configure this LSPV so that when the brake pressure exceeds a certain level, the inlet side pressure and the outlet side pressure can be changed to a relationship of approximately 1:1.

The present invention will be described below with reference to embodiments shown in the drawings.

Fig. 1 is a sectional view showing an LSPV that is an embodiment of the present invention, Fig. 2 is a schematic circuit diagram showing an air brake device using the LSPV, and Figs. 3 A, B, and C are for explaining the operation. FIGS. 4 and 5 are characteristic diagrams, and FIGS. 6A and 6B are a front sectional view and a plan view of the main parts.

First, the outline of the air brake device shown in FIG. 2 will be explained. An air tank 2 that stores air sent out from an air compressor 1 is connected to a brake valve 3 that responds to a brake pedal. The front brake chamber 4 is connected to the brake valve 3 via a quick release valve 5, and the rear brake chamber 6 is connected to the air tank 2 via a relay valve 7. Relay valve 7 is connected to brake valve 3 via LSPV 8. The LSPV 8 is installed on a frame 10a, and a load detection device (details will be described later) 9 is interposed between it and the axle 10b.

When the brake valve 3 operates, air from the air tank 2 is supplied to the front and rear brake chambers 4 and 6 via the quick release valve 5 and the relay valve 7, respectively. At this time,
In LSPV8, the pressure from brake valve 3 is reduced at a set rate, and this acts on relay valve 7, so the braking force on the rear side is suppressed more than that on the front side, thereby ensuring the desired distribution of braking force. will be done.

In this embodiment, the LSPV 8 includes a main body 11, and inside the main body 11, a first cylinder chamber 12 as a differential cylinder chamber is formed in a cylindrical hollow shape with different diameters. This cylinder chamber 12 includes a first piston 14 formed into a cylindrical shape with substantially different diameters, and a second piston 14 formed with the same diameter as the small diameter portion of the first piston 14.
A differential piston 13 consisting of a piston 15 is fitted so as to be slidable in the vertical direction. An inflow passage 16 is bored in the lower part of the main body 11 so as to face the large diameter lower surface space of the first piston 14 in the first cylinder chamber 12, and the inflow passage 16 is connected to the brake valve 3. The upper part of the main body 11 has an outflow passage 1.
7 is the first piston 1 in the first cylinder chamber 12
The outflow passage 17 is connected to the relay valve 7.

A valve chamber 18 is formed in the center of the upper part of the first piston 14, and the valve chamber 18 has a passage 19 formed on its side surface and is opened at its ceiling surface, thereby forming an inflow path for the first cylinder chamber 12. 1
6 side and the outflow path 17 side, respectively. Therefore, the valve chamber 18 substantially constitutes a passage connecting the inflow passage 16 and the outflow passage 17.

A valve plate 22 having an air supply port 21 formed in the center is fitted into the upper part of the valve chamber 18 and fixed by a retaining ring 23 . An air supply valve chamber 24 is formed at the periphery of the air supply port 21 of the valve plate 22 so as to protrude into a conical shape. As shown in FIG. 6, the valve plate 22 has a plurality of small holes 25 arranged in an annular shape surrounding the air supply port 21 as passages for communicating the inflow path 16 side and the outflow path 17 side. A check valve 26 formed into a substantially donut shape from an elastic material such as rubber or synthetic resin is fixedly held at its outer periphery on the end face of the valve plate 22 on the inflow passage 16 side. They are installed in close contact with each other. Check valve 26
The inner periphery of the intake valve seat 24 is formed to become gradually thinner along the conical slope of the air supply valve seat 24, and this inner periphery can be bent toward the inlet passage 16. That is, the check valve 26 is normally in close contact with the valve plate 22 to close the small hole 25, and when bent, it separates from the plate 22 and opens the small hole 25.

A supply/exhaust valve 27 is built into the valve chamber 18 with a compression spring 28 interposed between it and the bottom surface of the valve chamber in a stored state. , is configured to be seated in an exhaust valve chamber 52, which will be described later, and to be separated from the air supply valve seat 24.

A second piston 15 is fitted into the lower part of the small diameter portion of the first cylinder chamber 12 so as to abut against the first piston 14 so as to be able to move toward and away from the first piston 14. A back pressure chamber is provided at the abutting portion of both pistons 14 and 15. 29 is formed. Atmospheric chamber 3 is located below the second piston 15.
0 is formed and arranged at the bottom of the main body 11, and the atmospheric chamber 30 is connected to the filter 32 by the ventilation hole 31.
It is communicated with the atmosphere through. A compression spring 33 as an operating spring is interposed in the atmospheric chamber 30 in a stored force state between the second piston 15 and the bottom surface of the chamber. 14 is constantly energized to push it up.

A back pressure introduction passage 3 is provided in the center of the bottom wall of the first piston 14.
A valve holder 35 is inserted into the guide chamber 36 of the second piston 15, and is always urged upward by a compression spring 37. It is set up like this. The second piston 15 has a first air bleed passage 38 that communicates with the back pressure chamber 29 and the guide chamber 36, and a second air bleed passage 39 that communicates the guide chamber 36 with the atmospheric chamber 30. It is perforated. A back pressure introduction valve 40 is connected to the introduction passage 34 on the upper surface of the valve holder 35.
A cut valve 41 is provided on the lower surface of the holder 35 to control opening and closing of the second air vent passage 39 .

In the upper part of the main body 11, a second cylinder chamber 42 as a connecting cylinder chamber is formed adjacent to and continuous with the first cylinder chamber 12, and both chambers 42
A stopper 43 is recessed into the inner circumferential wall and protrudes from a portion adjacent to and 12. A third piston 44 as a connection piston is slidably fitted into the second cylinder chamber 42, and the upper surface space of the third piston 44 in the second cylinder chamber 42 is formed by the main body 11.
The filter 4 is
6 to the atmosphere. A compression spring 47 is installed in the atmospheric chamber of the second cylinder chamber 42 so as to press the third piston 44 against the stopper 43 . In the third piston 44, an exhaust path member 49 as a load sensing connection member formed in a cylindrical shape is slidably inserted into the central hole 48, and an exhaust hole 51 is provided in the upper part of the exhaust path member 49. The hollow portion 50 and the exhaust hole 51 substantially constitute an exhaust path. An exhaust valve seat 52 is formed on the lower end surface of the exhaust path member 49, and the exhaust valve seat 52 is configured to relatively enter and exit the air supply port 21 of the valve plate 22 fixed to the first piston 14. There is. A stopper 53 is fitted to the outer periphery of the intermediate portion of the exhaust path member 49, and a spring receiver 54 is fixed to the upper end of the exhaust path member 49, and is slidably fitted into the guide chamber 55. A compression spring 5 is provided between the spring receiver 54 and the third piston 44.
6 is interposed in a stored force state, and this compression spring 5
6, the exhaust path member 49 is pushed up against the third piston 44 and the stopper 53 is pushed up against the third piston 4.
It is designed to press against the lower surface of 4.

A shaft 58 to which a cam 57 as a final stage transmission section of the load detection device 9 is fixed is rotatably installed in the guide chamber 55, and a lever 59 is fixed to the cam shaft 58 outside the guide chamber 55. has been done. The lever 59 connects the link mechanism 6 to the axle 10b.
They are linked via 0. Therefore, the cam 57 moves in the link mechanism 6 in response to the relative displacement caused by the change in the load between the axle 10b and the frame 10a.
0, it is adapted to be rotated via a lever 59 and a shaft 58. The cam 57 is configured such that its cam surface moves away from the axis as the load increases.

Next, the operation will be explained with reference to FIGS. 3A, B, and C and FIG. 4.

Load sensing proportioning operation.

When the brake is not applied, the third piston 44 is pushed down by the compression spring 47 until it comes into contact with the stopper 43, and as a result, the exhaust path member 49, in which the stopper 53 is engaged with the piston 44 via the compression spring 56, It is deeply recessed into the valve chamber 18 of the first piston 14 of the differential piston 13 and is located at the lower limit. At this lower limit position, the cam 57, the exhaust path member 49, the third piston 44, the stoppers 43, 53, etc. relationship is set. In this state, the exhaust valve seat 5
A supply/exhaust valve 27 is pressed against the valve 2 by a compression spring 28, and the supply/exhaust valve 27 closes the hollow portion 50 and opens the air supply port 21 of the valve plate 22.

On the other hand, the differential piston 13 has an operating compression spring 3
3, it is pushed up and positioned at the upper limit.

When the brake is applied and pressure is supplied from the brake valve 3 to the inflow passage 16, the pressure becomes the first
The relay is connected to the lower surface of the third piston 44 via the lower part of the cylinder chamber 12, the passage 19 of the first piston 14, the valve chamber 18, the air supply port 21, and the upper part of the first cylinder chamber 12, and is connected to the lower surface of the third piston 44 from the outlet passage 17. It is sent to valve 7. When pressure is applied to the third piston 44, the piston 44 is pushed up against the compression spring 47, and following this, the exhaust path member 49 is raised until the upper surface of its spring receiver 54 comes into contact with the cam 57. Following this rise, the supply and exhaust valve 27 approaches the supply valve seat 24 of the first piston 14 located at the upper limit while remaining seated on the exhaust valve seat 52. At this time, the supply and exhaust valve 27
The distance between the air supply valve seat 24 and the air supply valve seat 24 is determined by the amount of rise of the exhaust path member 49 regulated by the cam 57.
The larger the load is, the larger the load becomes. That is, this state is the operating reference state of the air supply/exhaust valve 27, the air supply valve seat 24, and the exhaust valve seat 52.

When the pressure from the inlet passage 16 is sent out from the outlet passage 17, the differential piston 13 is gradually pushed down as the pressure acting on the effective area of the small diameter portion overcomes the upward force of the compression spring 33. When the air supply valve seat 24 comes into contact with the air supply/exhaust valve 27, the inflow path 16
The supply from the outlet to the outlet 17 is cut off, and this point becomes the split point. When the pressure in the inflow path 16 further increases from this state, the differential piston 13 is pushed up and the air supply valve seat 24 opens, so that pressure is supplied from the inflow path 16 to the outflow path 17 again. Then, when pressure corresponding to the ratio of the large diameter lower effective area and upper effective area of the differential piston 13 is supplied, the piston 13 is pushed down again and closes the air supply valve seat 24 (in this way, the air supply valve seat 24 is closed). A state in which both the air valve seat 24 and the exhaust valve seat 52 are closed is called a balanced state (see FIG. 3A). In this way, the pressure in the outflow path 17 is increased at a predetermined pressure reduction ratio relative to the pressure in the inflow path 16.

When the pressure in the inlet passage 16 is lowered from the balanced state, the differential piston 13 moves to the supply/exhaust valve 27.
At the same time, the exhaust valve seat 52 is pushed down and the exhaust valve seat 52 is opened, and the pressure on the outflow path 17 side is exhausted, so that the original balanced state is restored again. In this way, the inflow path 1
6 and the pressure of the outflow path 17 are reduced in pressure proportioning.

Then, the cam 57 rotates according to the loaded load, and the raised positions of the exhaust path members 49 are different, and the amount of deflection of the operating compression spring 33 is changed, so that the spring acting upwardly on the differential piston 13 is changed. Since the forces of 33 are different, a proportioning characteristic line corresponding to each live load is obtained as shown in FIG.

As mentioned above, as the pressure in the inflow path 16 is lowered, the pressure in the outflow path 17 gradually decreases, but even when the pressure in the inflow path 16 reaches 0, it acts upward on the differential piston 13. Actuation spring 33
The pressure in the outflow path 17 that balances only the force remains on the outflow path side.

In order to prevent this, a check valve 26 is provided on the valve plate 22, and when the pressure in the inflow path is below the split point, the pressure in the inflow path and the pressure in the outflow path decrease at a ratio of 1:1. It turns out.

That is, when the pressure is reduced, the check valve 26 is brought into close contact with the valve plate 22 due to the force caused by the difference between the pressure in the inlet passage 16 and the pressure in the outlet passage 17, and the small hole 25 is brought into close contact with the valve plate 22.
The group is blocked. However, when the pressure in the outflow path 17 increases due to the pressure in the inflow path 16, the check valve 26 is pushed toward the inflow path through the small hole 25, as shown by the imaginary line in FIG.
It is bent and lifted up from the valve plate 22 to open a group of small holes 25. As a result, the outflow path 1
7 flows back to the inflow path 16 side through the group of small holes 25, so the pressure in the outflow path 17 decreases. Due to this action, the balance state of the differential piston 13 is disrupted, and the differential piston 13 is pushed up.
The air supply valve seat 24 opens and returns to its initial state, and the pressure in the inflow path 16 and the pressure in the outflow path 17 become 1:1. Therefore, the pressure in the outflow path 17 is the same as that in the inflow path 1.
6 becomes 0 at the same time as the pressure becomes 0, thereby removing all braking force from the rear wheels.

Operation when the pressure reduction action is released When the pressure Pi supplied to the inflow passage 16 exceeds the set value Pid defined by the compression spring 37, the valve holder 35 is pushed down against the compression spring 37. This causes the cut valve 41 to move to the second position.
The air vent passage 39 is closed, and the back pressure introduction valve 40 opens the introduction passage 34. Along with this, the pressure in the inflow passage 16 is guided to the back pressure chamber 29 between the first piston 14 and the second piston 15 via the introduction passage 34, so that the upper surface of the large diameter portion of the first piston 14 The area ratio with the lower surface is approximately 1:1, and the pressure Pi in the inflow path 16 and the pressure Po in the outflow path 17 are approximately equal. In other words, as shown in Figure 5,
When the pressure Pi in the inflow path 16 becomes equal to or higher than the set value Pid, the proportioning action is canceled.

According to this embodiment, during non-braking, the cam as the final transmission member in the load detection device is not connected to the exhaust path member as the load sensing connection member that establishes the connection between the intake and exhaust valve and the intake valve seat. Since contact is maintained, wear, failure, malfunction, etc. of each component of the LSPV can be prevented, and durability and
Performance etc. can be improved. In other words, since the load detection device detects the relative displacement between the frame and the axle, when the vehicle is traveling on an uneven road surface, the cam, which is the final transmission member, also moves violently, which causes the exhaust path member to move violently. If they are in constant contact, each component of the LSPV will move violently, and this movement can cause wear, failure, and malfunction. However, if the transmitting member and the transmitted member are not in contact, the movement of the transmitting side is
Since it is not transmitted to the transmitted side, drift is avoided,
The harmful effects associated with this can be prevented.

Additionally, during braking, the pressure supplied from the brake valve to the inflow path automatically brings the exhaust path member (transmitted member) into contact with the cam (transmission member), ensuring normal load sensing proportioning operation. At the same time, it is possible to omit a device for forcing contact based on a detection signal during braking, simplifying the structure, and ensuring safety.

The differential piston has a composite structure of a first piston and a second piston, and when the pressure in the inflow path exceeds a set value, such as during sudden braking, the pressure in the inflow path is introduced to the back of the first piston. With this configuration, the air supply port between the inflow and outflow channels can be left open, so the decompression that is the proportioning function can be stopped during sudden braking, etc. This eliminates the fear of insufficient braking force during sudden braking in the event that the compression spring or the link mechanism of the load detection device is damaged, and safety can be ensured. In other words, there is no particular need to provide a failsafe mechanism.

According to this embodiment, a small hole is drilled in the valve plate of the differential piston, and a plate-shaped check valve is installed to open and close this small hole, thereby simplifying the structure and preventing residual pressure on the outflow path side. can, and
The assembly space is extremely small, making the LSPV smaller and lighter, which reduces manufacturing costs.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be modified without departing from the gist thereof.
It goes without saying that various changes are possible.

The load detection device is not limited to a configuration using a cam, but may also include a configuration in which the intermediate portion is rotatably supported, one end linked to an axle, and the other end facing an exhaust path member, etc.
A configuration using a binion rack mechanism or the like may be used.

The passage connecting the inflow passage and the outflow passage and the check valve may be arranged on the supply/exhaust valve side.

As described above, according to the present invention, the propagation of the loose movement of the load detection device can be blocked during non-braking.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an LSP valve which is an embodiment of the present invention, Fig. 2 is a schematic circuit diagram showing an air brake device using the LSP valve, and Figs. 3 A, B, and C explain the operation. 4 and 5 are characteristic diagrams, and FIGS. 6A and 6B are a front sectional view and a plan view of the main parts. 1... Air compressor, 2... Air tank, 3... Brake valve, 4... Front brake chamber, 5... Quick release valve,
6... Rear brake chamber, 7... Relay valve, 8... LSP valve, 9... Load detection device, 1
0a...Frame, 10b...Axle, 11...
...Body, 12...First cylinder chamber (differential cylinder chamber), 13...Differential piston, 14...First piston, 15...Second piston, 16...Inflow path,
17... Outlet passage, 18... Valve chamber, 19... Passage,
21...Air supply port, 22...Valve plate, 23
... Retaining ring, 24 ... Air supply valve seat, 25 ... Small hole, 26 ... Check valve, 27 ... Supply and exhaust valve, 29 ...
... Back pressure chamber, 30 ... Atmospheric chamber, 31 ... Ventilation path, 3
2... Filter, 33... Compression spring for operation, 34
...Introduction path, 35...Valve holder, 36...Guide chamber, 37...Compression spring, 38, 39...Air vent path, 40...Back pressure introduction valve, 41...Cut valve, 4
2...Second cylinder chamber (contact cylinder chamber), 4
3...Stopper, 44...Third piston (contact piston), 45...Air passage, 46...Filter,
47... Compression spring for spacing, 48... Center hole, 49
...Exhaust path member (load sensing connection member),
50...Hollow part, 51...Exhaust hole, 52...Exhaust valve seat, 53...Stopper, 54...Spring holder, 55
...Guide chamber, 56...Compression spring, 57...Cam, 58...Camshaft, 59...Lever, 60...
link mechanism.

Claims (1)

[Claims] 1. A main body 11, a first cylinder chamber 12 formed inside the main body 11 in a cylindrical hollow shape with different diameters, and a first piston 14 formed in a cylindrical shape with different diameters.
and a second piston 15 formed to have the same diameter as the small diameter portion of the first piston 14, and a differential piston 13 fitted in the first cylinder chamber 12 so as to be slidable in the vertical direction; and a main body 11. An inlet passage 16 is formed in the lower part of the main body 11 so as to face the large-diameter lower surface space of the first piston 14 in the first cylinder chamber 12 and is connected to the brake valve 3. The outflow path 1 is bored so as to face the upper surface space of the first piston 14 at 12 and is connected to the relay valve 7.
7, a valve chamber 18 formed at the center of the upper part of the first piston 14 and communicated with the inlet passage 16 side and the outlet passage 17 side of the first cylinder chamber 12, respectively; formed at the upper part of the valve chamber 18. Air supply port 21
and an air supply valve seat 2 formed around the periphery of the air supply port 21
4 and the supply/exhaust valve spring 2 between the valve chamber 18 and the bottom of the valve chamber.
8 is installed and built-in in a power storage state, and the first
When the piston 14 is at the upper limit, the air supply/exhaust valve 27 is seated on an exhaust valve seat 52 (described later) and is spaced from the air intake valve seat 24, and the second piston 15 is located at a lower position in the main body 11. Atmospheric chamber 3 is formed in and communicates with the atmosphere.
0, the differential piston 13 is interposed between the second piston 15 and the bottom surface of the chamber in the atmospheric chamber 30 in a power-storing state.
an actuating spring 33 that is always biased to push up; a guide chamber 55 formed above the first cylinder chamber 12 in the main body 11 and communicating with the atmosphere; and a spring receiving portion in the guide chamber 55. 54 is fitted to be slidable in the vertical direction, and a cylindrical exhaust path member 49 whose lower end is inserted so as to relatively go in and out of the air supply port 21, and one end of which is locked to the spring receiver 54. , exhaust path member 4
9, an exhaust valve seat 52 formed in an annular shape on the lower end surface of the cylindrical wall of the exhaust passage member 49, and an exhaust valve seat 52 formed on the cylindrical wall of the exhaust passage member 49 and located in the hollow of the cylinder. It is equipped with an exhaust hole 51 that communicates the inside and outside of the part 50, and a load detection device 9 that extracts the amount of relative displacement between the vehicle body and the axle and transmits it to the exhaust path member 49. In the load sensing proportioning valve, which is configured to create a split point corresponding to the load by changing the position of the exhaust path member 49 relative to the differential piston 13, a third piston is disposed in the upper part of the main body 11. 44 is fitted in the second cylinder chamber 4 so as to be slidable in the vertical direction.
2 is formed adjacent to the first cylinder chamber 12, and a stopper 43 is provided protruding from the adjacent portion of the first cylinder chamber 12 and the second cylinder chamber 42. A space above the third piston 44 in the chamber 42 is communicated with the atmosphere, and a third piston spring 47 is installed in this space so as to push the third piston 44 against the stopper 43. On the other hand, the exhaust passage member 49 is slidably fitted into the third piston 44, and the third piston 44 and the exhaust passage member 49 are connected to the exhaust passage for the third piston 44 by a stopper 53. The exhaust path member 49 is interlocked to restrict upward movement of the member 49, and the exhaust path member 49 is opposed to the final transmission member 57 of the load detection device 9 so as to be able to freely come into contact with it. The third piston 44 is pushed down by the third piston spring 47 until it comes into contact with the stopper 43.
The exhaust path member 49 with which the stopper 53 is engaged with the piston 44 is connected to the first piston 14 of the differential piston 13.
In order to prevent the final transmission member 57 of the load detection device 9 from coming into contact with the upper surface of the exhaust path member 49 even at the maximum load at the lower limit position where the valve chamber 18 is deeply inserted and located at the lower limit. Load detection device 9, exhaust path member 49, third piston 4
4. The relationship between the stoppers 43 and 53 is set, and in this state, the supply and exhaust valve 2 is mounted on the exhaust valve seat 52.
7 is pressed by the supply/exhaust valve spring 28, and the supply/exhaust valve 27 closes the hollow portion 50 and closes the air supply port 2.
1 is open, and on the other hand, the differential piston 13 has an operating compression spring 33
A load sensing proportioning valve characterized by being pushed up by the upper limit and positioned at the upper limit.