JPS6099748A - Load sensing proportioning valve - Google Patents

Abstract

PURPOSE:To prevent each of constituent parts from wear and wrong operation, by putting a cam or a final transmitting member for a load detecting device and an exhaust passage member or a load sensing connection member all into a noncontact state in time of nonbraking, while making the both contact each other in time of braking the other way. CONSTITUTION:In time of non-braking, a piston 44 is pressed to a stopper 43 with a compression spiral spring 47. A stopper 53 of an exhaust passage member 49 is made contact with this piston 44 by means of another compression spring 53. The exhaust passage member 49 is situated in the lower limit position embedded in a valve chest 18 in a first piston 14 of a differential piston 13 whereby at this lower limit position, even in case of maximum loading capacity, a cam surface of a cam 57 is in no case touched to the exhaust passage member 49. Likewise, in time of braking, compressed air is delivered out of an outflow passage 17 by way of an inflow passage 16, a valve's air- charging port 21 and an undersurface of the third piston 44. When pressure acts on the piston 44, this piston 44 goes up, and the exhaust passage member 49 also goes up in follow-up to the piston 44 and contacts the cam 57. With this constitution, such force as being commensurate to load capacity acts on the exhaust passage member 49, thus a characteristic of a P valve commensurate to the load is securable.

Description

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

In general, it is considered ideal that the braking force in vehicles such as automobiles should be distributed between the front and rear wheels so that they lock simultaneously.
This characteristic line 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 the valve provided between the pressure medium inflow path and the pressure medium outflow path according to the amount of displacement, as shown in Figure 4. Then, each braking force distribution line approximate to the ideal braking force distribution curve (imaginary line) corresponding to each load is obtained. 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 path and outflow path. The differential piston that controls the opening and closing of the installed valve is constantly energized (7) The operation of this piston is controlled by changing the strength of the splash, and the split point corresponding to the load is set. configured to produce.

However, in such an LS PV, the spring serving as the load detection means constantly biases the differential piston, so when the brake is not applied, the differential piston will expand and contract due to the vertical movement of the frame. It has the disadvantage that it is allowed to move loosely, causing wear, failure, malfunction, etc.

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

Another object of the present invention is to configure the brake system so that when the brake pressure exceeds a certain value at t, 5 pvic, the inlet side pressure and the outlet side pressure can be changed to a relationship of approximately 1:1.

Hereinafter, the present invention will be explained according 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 Fig. 3 (AI, +81, (CI indicates the operation). 4 and 5 are respective characteristic diagrams, and FIG. 6A) and (Bl 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 the air sent out from the near 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 the quick release valve 5, and the rear brake chamber 6 is connected to the lever L/
- connected to the air tank 2 via valve I; Relay valve 7 is connected to brake pulp 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 4.6 via the quick release valve 5 and the relay valve I. At this time, the pressure from the brake pulp 3 is set at LSPVg. Since the pressure is reduced at the same rate and this acts on the relay valve 7, the braking force on the rear side is suppressed more than that on the front side, thereby ensuring a desired distribution of braking force.

In this embodiment, the LSPVg includes a main body 11, and inside the main body 11, a first cylinder 12 as a differential cylinder chamber is formed in a cylindrical hollow shape with different diameters. In this cylinder chamber 12, a differential piston 1 consisting of a first piston 14 formed in a cylindrical shape with substantially different diameters and a second piston 15 formed with the same diameter as the small diameter portion of the first piston 14 is provided.
3 is fitted so as to be slidable in the vertical direction. An inflow passage 16 is provided in the lower part of the main body 11 to connect the first cylinder chamber 12 to the first cylinder chamber 12.
It is bored so as to face the large-diameter lower surface space of the piston 14, and the inflow passage 16 is connected to the brake valve 3. In the upper part of the main body 11, the outflow passage 11 is connected to 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.
The inlet passage 16 side and the outlet passage 17 side of the cylinder chamber 12 are communicated with each other.

Therefore, the valve chamber 18 substantially constitutes a passage connecting the inflow passage 16 and the outflow passage 11.

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 the valve plate 22 is fitted into the upper part of the valve chamber 18.
It is more established than c. Air supply port 2 of valve plate 22
As shown in FIG. 6, an air supply valve seat 24 is formed on the periphery of the pulp plate 22 so as to protrude into a conical shape.As shown in FIG. A plurality of small holes 25 serving as passages are arranged in an annular manner surrounding the air supply port 21, and are bored through the valve plate 2.
A check valve 26 formed from an elastic material such as rubber or synthetic resin into a substantially donut shape is provided on the end face of the inflow passage 16 side of 2.
are fixedly held at their outer peripheries and attached in close contact with each other. The inner periphery of the check valve 26 is formed so as to become gradually thinner along the conical slope of the air supply valve pressure 24, and this inner periphery forms a trap so that it can be bent toward the inlet passage 16. . That is, the check valve 26 is normally in close contact with the valve port 22 to close the small hole 25, and when bent, it is separated from the valve port 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, and the first piston 14 is located at the upper limit of the supply/exhaust valve 27. At this time, the intake valve seat 24 is seated on the exhaust *I%52, which will be described later.
It is now possible to leave the seat.

A second piston 15 is fitted into the lower part of the small diameter portion of the first cylinder 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, and a back pressure chamber 29 is provided at the abutting portion of both pistons 14 and 15. An atmospheric chamber 30 is formed at the bottom of the main body 11 and is disposed below the second piston 15 in which the filter 32 is formed.
It is communicated with the atmosphere through. In the atmospheric chamber 30, a compression spring 33 as an operating spring is interposed between the second piston 15 and the bottom surface of the chamber in a stored state.
The first piston 14 that abuts the second piston 15 is constantly biased to push up.

A back pressure introduction passage 34 is bored in the center of the bottom wall of the first piston 14 so as to communicate between the valve chamber 18 and the back pressure chamber 29, and a valve holder 35 is fitted into the guide chamber 36 of the second piston 15. The second piston 15 has a first air bleed passage 38 which communicates with the back pressure chamber 29 and the guide chamber 36.
Further, a second air vent passage 39 is formed so as to communicate the guide chamber 36 and the atmospheric chamber 30, respectively. Valve holder 3
A back pressure introduction valve 40 is provided on the top surface of the holder 35 to control opening and closing of the introduction path 34, and a cut valve 4 is provided on the bottom surface of the holder 35.
1 is provided 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 so as to be continuous with and adjacent to the first cylinder chamber 12.
A first stopper 43 is recessed into the inner circumferential wall and protrudes.

The second cylinder chamber 42 has a third cylinder as a connecting piston.
A piston 44 is fitted in a slidable manner, and the upper surface space of the third piston 'Q-, 4 in the second cylinder chamber 42 is filled with a ventilation hole 45 formed in the upper part of the main body 11 through a filling 46. It is connected to the atmosphere. A compression spring 41 is installed in the atmospheric chamber of the second cylinder seedling 42 so as to press against a stopper 43, which is a third piston blade. 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. Exhaust passage member 49g) An exhaust valve seat 52 is formed on the lower end surface, and the exhaust valve seat 52 is configured to relatively enter and exit the air supply port 21 of the nokulp plate 22 fixed to the first piston 14. It has become. A stopper 53 is fitted to the outer periphery of the intermediate portion of the exhaust path member 49, and a guide chamber 55 is fitted to the upper end of the exhaust path member 49.
A spring receiver 54 that is slidably fitted is fixedly attached to the spring receiver 54 .

A compression spring 56 is provided between the spring receiver 54 and the third piston 44.
is interposed in a stored force state, and the exhaust passage member 49 is pushed up against the third piston 44 by the compression spring 56 so as to press the stopper 53 against the lower surface of the third piston 44. .

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 mounted on the cam shaft 58 outside the guide chamber 55 . It's stuck. V bar 59&'! , are linked to the axle 10b via a lick mechanism 60.

Therefore, the cam 57 is rotated via the link mechanism 6o, the lever 59, and the shaft 58 in response to the relative displacement due to a change in the load between the axle 10b and the frame 102. The cam 57 is configured such that its cam surface moves away from the axis as the load increases.

Next, the action will be explained with reference to FIG. 3 (Al[81[C1] and FIG. 4).

1　Load sensing proportioning link activated.

When not braking, the third piston 44 is compressed by the compression spring 4
7 until it comes into contact with the stopper 43,
As a result, the exhaust path member 49 with which the stopper 53 is engaged with the piston 44 via the compression spring 56 is deeply recessed into the valve chamber 18 of the first piston 14 of the differential piston 13 and is positioned at the lower limit. At this lower limit position, even if the load is the maximum, the cam surface is
The relationship between the cam 57, the exhaust path member 49, the third piston 44, the stopper capital 53, etc. is set so as not to contact the upper surface of the spring receiver 54. In this state, the supply/exhaust valve 27 is pressed against the exhaust valve seat 52 by the compression spring 28, and the supply/exhaust valve 27 closes the hollow portion 50 and closes the valve plate 27.
The air supply port 21 of No. 2 is open.

On the other hand, the differential piston 13 is pushed up by the operating compression spring 33 and is positioned at the upper limit.

When the brake is applied and pressure is supplied from the brake valve 3 to the inlet passage 16, the pressure is supplied to the lower part of the first cylinder chamber 12, the passage 19 of the first piston 14, the valve chamber 18, and the air supply port 2.
1. It joins the lower surface of the third piston 44 via the upper part of the first cylinder chamber 12, and is sent out from the outflow path 17 to the relay valve 7. When pressure is applied to the third piston 44, the piston 44 is pushed up against the compression spring 41, 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 51. 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 air supply and exhaust valve 27 and the air supply valve seat 2
4 is determined by the amount of rise of the exhaust path member 49 regulated by the cam 57, and becomes larger when the load is large. 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. Then, when the air supply valve seat 24 comes into contact with the air supply/exhaust valve 27, the supply from the inflow path 16 to the outflow path 17 is cut off, and this point becomes a 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). Air valve seat 2
4 and the exhaust valve seat 52 are both closed, which is called a balanced state.

See Figure 3 fAI. ). 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 inflow path 16 is lowered from the balanced state, the differential piston 13 is pushed down together with the supply/exhaust valve 27, the exhaust valve seat 52 opens, and the pressure on the outflow path 11 side is exhausted, so that the original balance is restored again. Return to state. In this way,
The pressure in the inflow path 16 and the pressure in the outflow path 17 are reduced by pressure reduction blobbing.

Then, the cam 57 rotates according to the loaded load, and the ascending positions of the exhaust path members 49 are different from each other.
By changing the deflection view of 3, the differential piston 13
Since the force of the spring 33 acting in the upward direction differs, the provisional log %fi [corresponding to each live load can be obtained as shown in FIG. 4.

As mentioned above, as the pressure in the inflow path 16 decreases, the pressure in the outflow path 17 gradually decreases, but even if the pressure in the inflow path 16 reaches 0, the differential piston 13Vc continues to work upward. (The pressure of the outflow path 17 that balances only the force of the actuating spring 33 remains on the outflow path side.

In order to prevent this, a check valve 26 is provided in the valve port 22, and when the pressure in the inflow path is below the Sgerritt point, the pressure in the inflow path and the pressure in the outflow path are
It will go down 1:1.

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 inflow path 16 and the pressure in the outflow path 17, thereby closing the group of small holes 25. Only 17
When the pressure in the outflow path 17 becomes higher than the pressure in the inflow path 16, the check valve 26 is pushed toward the inflow path through the small hole 25, and is bent as shown by the imaginary line in FIG. , is lifted up from the valve plate 22 and opens a group of small holes 25.

As a result, the pressure in the outflow path 17 flows back toward the inflow path 16 through the group of small holes 25, so that the pressure in the outflow path 17 decreases. Due to this action, the balance state of the differential piston 13 is disrupted, the differential piston 13 is pushed up, and the air supply valve seat 24 is pushed up.
opens and returns to the initial state, and the pressure in the inflow path 16 and the outflow path 1
7 pressure will be 1:1. Therefore, the pressure in the outflow path 17 becomes 0 at the same time as the pressure in the inflow path 16 becomes O,
This removes all braking force from the rear wheels.

jj When the pressure Pi supplied to the operating inflow path 16 when the depressurization action is released becomes equal to or higher than the set value Pid defined by the compression spring 3T, the valve holder 3
5 is pushed down against the compression spring 37. As a result, the cut valve 41 closes the second air vent passage 39, and the back pressure introduction valve 4o opens the introduction passage 34.

Accordingly, the pressure in the inflow passage 16 is transferred to the back pressure chamber 2 between the first piston 14 and the second piston 15 via the introduction passage 34.
9, the area ratio of the upper surface to the lower surface of the large diameter portion of the first piston 14 is approximately 1:1, and the inflow passage 16
The pressure Pi of the outlet passage 17 and the pressure PO of the outlet passage 17 are approximately equal. That is, as shown in FIG. 5, when the pressure Pi of the inflow path 16 becomes equal to or higher than the set value Pic1, the provisioning 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. To maintain the contact state, LSP
Abrasion, failure, malfunction, etc. of each component of V can be prevented and durability is ensured.

Performance etc. can be improved. In other words, the load detection device detects the relative displacement between the frame and the axle.
When the vehicle is running on an uneven road surface, the final transmission member, the cam, moves violently, and if the exhaust path member is in constant contact with this cam, each component of the LSPV also moves violently.
This loose movement causes wear, failure, and malfunction. but,
If the transmitting member and the transmitted member are not in contact with each other, the movement of the transmitting side is not transmitted to the transmitted side, so that free movement is avoided.
The negative effects associated with this should be prevented.

Furthermore, during braking, the exhaust path member as the transmitted member can be automatically brought into contact with the cam as the transmitting member by applying pressure to the inflow path from the brake pulp.
Not only can normal load sensing proportioning operation be ensured, but devices that force contact based on braking detection signals can be omitted, 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 structure, the air supply port between the inflow and outflow channels can be left open, so the pressure reduction, which is a provisioning function, can be stopped in the event of 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 need to specifically provide a fail-safe 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. You can do it in a row, and.

The assembly space will be extremely small, making the LSPV smaller and lighter, and manufacturing costs reduced.

Note that the present invention is not limited to the above embodiments,
It goes without saying that various changes can be made without departing from the gist of the invention.

The load detection device is not limited to a configuration using a cam, but also 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., or a configuration using a binion rack mechanism. etc. (1°) The passage connecting the inflow path and the outflow path and this check valve may be arranged on the supply/exhaust valve side.As explained above,
According to the present invention, transmission of loose movement of the load detection device W can be blocked during non-braking.

[Brief explanation of the drawing]

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 Fig. 3 shows the functions of I, fBl, and fQ. Each schematic sectional view for explanation, FIG. 4 and FIG.・Air tank, 3
... Brake pulp, 4 ... Front brake chamber, 5 ... Quick release pulp, 6 ... Rear brake chamber, 7 ... Relay valve, 8 ... L
SP pulp, 9... Load detection device, 10a... Frame, 10b... Axle, 11... Main body, 12...
...First cylinder chamber (differential cylinder chamber), 13...Differential piston, 14...First piston, 15...Second
Piston, 16°°°Inflow path, 17...Outflow path, 18
... Valve chamber, 19 ... Passage, 21 ... Air supply port, 22
...Valve plate, 23.°° stop ring, 24.
-・Air supply valve seat, 25...Small hole, 26...Check valve, 2
7... Supply/exhaust valve, 29... Back pressure chamber, 30... Atmospheric chamber, 31... Ventilation path, 32...-Fill, 33...
・Compression spring for operation, 34...Introduction path, 35...Valve holder, 36...Guide chamber, 37...Compression spring, 38
．． 39... Air vent passage, 40... Back pressure introduction valve, 41
...Cut valve, 42...Second cylinder chamber (contact cylinder chamber, 43...Stopper, 44...Third piston (contact piston), 45...Vent 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 pressure, 53...Stotsunok. 54... Spring holder, 55... Guide chamber, 56... Compression & spring, 57... Cam, 5B... Cam a, 59...
・・Reno=−,6゜・・Link blurred image). Patent applicant Miwa Seiki Co., Ltd. Agent Tatsuya Kajiwara Figure 3 (C) Figure 6 Figure 4-1 5th session l-

Claims (1)

[Claims] (1) A differential cylinder chamber in which an inflow passage and an outflow passage are established, a differential piston housed in this cylinder chamber that reciprocates in response to the pressure in the inflow passage, and this Noviston in the backward motion direction. A normally energized spring and a normally open valve formed in a passage between the inflow passage and the outflow passage and closed by forward movement of the differential IJh piston are constantly communicated with the differential cylinder chamber. A connecting cylinder chamber, a connecting piston housed in the cylinder chamber that moves forward when pressure is supplied, a biasing means that constantly biases this piston in a backward motion direction, and a connecting piston that is relatively linked to the valve. and a load sensing connection member that is linked to the connection piston and connects to a load detection device when the piston moves forward to create an operating reference state of the valve.