JPS6099750A - Load sensing proportioning valve - Google Patents

Abstract

PURPOSE:To make braking force distribution approximate to an ideal braking force distribution curve according to loading capacity in making full use of air suspension pressure, by letting the air suspension pressure of a car act on an LSPV controlling piston. CONSTITUTION:Air suspension pressure is led into a second cylinder chamber 39 and this pressure acts on each of pistons 41 and 42. Such force that substracts one in a spring 49 from the combined force of these pistons 41 and 42 produced by this air suspension pressure acts on a first piston 14 via a second piston 30. That is to say, such force as being commensurate to loading capacity acts on the first piston 14. And, with each effective area of the inner piston 41 and the outer piston 42 and force of a compression spring 49 selected properly, LSPV characteristic at every car are set up.

Description

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

In general, 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 they lock simultaneously, and this characteristic line is called the ideal braking force distribution curve. is known to vary depending on the live load.

LSPV is used to obtain braking force distribution lines that are as close as possible to the ideal braking force distribution curve, which differs depending on the loaded load, depending on the loaded load, and usually the relative displacement between the vehicle body and the rear axle is determined by the link mechanism. etc., and by controlling the opening and closing of the pressure medium between the inflow and outflow channels according to the amount of displacement, the brake pressure of the rear wheels is adjusted, and each approximate control as shown in Fig. 4 is applied. It is designed to obtain a power distribution characteristic line. The refraction point (braking force adjustment starting point) shown in FIG. 4 is called a split point.

However, in conventional L and SpV of this type, the relative displacement amount Y between the vehicle body and the rear axle is extracted by an IJ link mechanism, etc. and converted into the amount of spring deflection, and this spring force is used to create a split point at each load. Because of this structure, the groove construction tends to be complicated and the cost tends to be high.

On the other hand, the change in internal pressure (hereinafter referred to as air suspension pressure) of an air suspension equipped with a vehicle height adjustment device installed on large vehicles such as trucks and buses is approximately proportional to the change in the live load. It is conceivable that this air suspension pressure can be used to control the braking force.The purpose of the present invention is to create a braking force distribution characteristic curve that approximates the ideal braking force distribution curve in response to changes in live load by using the air suspension pressure. LS that can obtain
An object of the present invention is to provide a PV.Hereinafter, the present invention will be explained according to embodiments shown in the drawings.

Fig. 1 is a vertical cross-sectional view showing an LSPV that is an embodiment of the present invention, and Fig. 2 is a schematic circuit diagram showing an air brake device using the LSPV.
are schematic cross-sectional views for explaining the action. FIGS. 4 and 5 are line diagrams. First, the outline of the air brake device shown in FIG. 2 will be explained. A brake pulp 3 that responds to a brake pedal is connected to an air tank 2 that stores air delivered from the near compressor 1. The front brake chamber 4 is connected to the brake valve 3 via a quick release pulp 5, and the rear brake chamber 6 is connected to the air tank 2 via a relay valve 7. The relay valve 7 is connected to the brake valve 3 via the LSPV8, and the air suspension pressure in the air suspension 9 is guided to the LSPVQ. The air suspension 9 is interposed between the frame 10 and the axle 1Qb, and is configured to supply pressure into the bellows in accordance with the load to keep the vehicle height constant at all times. Therefore, the change in the bellows pressure (air suspension pressure) at tJ in the air suspension 9 is approximately proportional to the load.

When the brake knob 3 is actuated, air from the air tank 2 is supplied to the front and rear brake chambers 4, 6 via the quick release pulp 5 and the relay pulp 7, respectively. At this point, LSPV8, the pressure from the brake valve 3 is reduced at a set rate,
Since this acts on the relay valve T, the braking force on the rear side II is suppressed more than that on the front side, thereby ensuring a desired distribution of braking force.

In this embodiment, the LSPV 8 is equipped with a main body 11, and inside the main body 11, a differential cylinder chamber and a first cylinder chamber 12 are formed in hollow cylindrical shapes with different diameters. , a first piston 14 formed into a cylindrical shape with substantially different diameters, and a second piston 30 formed with the same diameter as the small diameter portion of the first piston 14.
3 is fitted in such a way that it can be slid vertically. Main body 11
The upper IC is bored such that an inflow passage 15 faces the large-diameter lower surface space of the first piston 14 in the first cylinder chamber 12, and the inflow passage 15 is connected to the cylinder valve 3. A waterfall outlet passage 16 is bored in the upper part of the main body 11 so as to face the upper surface space of the first piston 14 in the first cylinder chamber 12, and the outlet passage 16 is provided with the above-mentioned 1)-pulp T.
Be connected to. An exhaust passage 17 is vertically perforated approximately in the center of the upper part of the main body 11, and the upper end of the exhaust passage 17 is opened to the atmosphere through filters 18y' and 18r. The lower end of the exhaust passage 17 protrudes downward from the ceiling surface of the cylinder chamber 12, and an annular exhaust valve seat 19 is formed at the lower end of the protrusion.

A valve chamber 20 is formed in the center of the upper part of the first piston 14, and the valve chamber 20 has a passage 21 formed on its side surface and is opened at its ceiling surface to allow the inflow of the first cylinder chamber 12. The passage 15 side and the outflow passage 16 side are communicated with each other. Therefore, the valve chamber 20 substantially constitutes a passage connecting the inflow passage 15 and the outflow passage 16.

An air supply port 22a is formed in the center of the upper part of the valve chamber 20.
A retaining ring 23 is fitted with a pulp plate 22.
It is firmly established. Air supply port 2 of pulp plate 22
An air supply valve seat 24 is provided concentrically with the exhaust valve seat 19 and protrudes from the periphery of the valve 2a.

The valve chamber 20 has a built-in supply/exhaust valve 25 and a back pressure introduction valve 26 with a compression spring 27 interposed therebetween in a stored state. When the first piston 14 is at the upper limit, the supply/exhaust valve 25 is seated on the exhaust valve seat 19 and the intake/exhaust valve 25 is seated on the intake valve seat 24.
It is now possible to leave the seat. A cut valve holder 28 is slidably inserted into the central hole formed in the lower part of the first piston 14 so that the upper end surface protrudes from the bottom surface of the valve chamber 20 under normal conditions. A back pressure introduction passage 29 is formed so as to communicate the valve chamber 20 with a back pressure chamber 31 to be described later. The back pressure introduction valve 26 seats on the upper surface of the holder 28 and closes the introduction path 29 when the holder 28 protrudes from the bottom surface of the valve chamber 20.
When recessed from the bottom surface of the valve chamber 20, it is supported by the bottom surface of the valve chamber 20 and opens the introduction passage 29.

A second piston 30 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 31 is formed in a stable manner.

A cut valve 32 is provided in the central hole formed in the second piston 30.
is slidably inserted therein, and an air vent passage 33 is bored in the lower part of the cut valve 32 in an 'r-shape. The cut valve 32 has its upper end attached to the lower end of the holder 28.
The lower ends thereof are arranged so as to abut against the upper ends of an inner piston 41, which will be described later. A compression spring 34 is interposed in a stored force state between the lower surface of the first piston 14 and the cut valve 32 in the back pressure chamber 31, and the cut valve 32 is in a state of storing force when the support of the inner piston 41 is released. The biasing force of the compression spring 34 prevents the air bleed passage 33 from being closed.

An atmospheric chamber 35 is formed in the lower shoulder of the 2g2 piston 30 in the main body 11, and this chamber 35 is communicated with the atmosphere through a filter 37 through a vent hole 36 bored in the lower part of the main body 11. 11, a second cylinder chamber 39 as a control cylinder chamber is formed intermittently with the atmospheric chamber 35 via a partition wall 38, and this cylinder chamber 39 includes an inner piston 41 and an outer piston 42. A double structure control piston 40 is fitted with a length of 2t. A ventilation hole 43 is formed in the partition wall 38 so as to communicate the upper side 'J39a of the outer piston 42 in the second cylinder chamber 39 with the atmospheric chamber 35.

A near suspension pressure introduction passage 44 is bored in the lower part of the main body 11 so as to communicate with the lower chamber 39b of the double-structured control piston 40 in the two-cylinder chamber 39.
The internal pressure (air suspension pressure) of the Oker bellows is introduced into the air suspension 9.

The inch piston 41 has a central hole 45 formed in the partition wall 38.
It is slidably inserted into the piston 30 and abuts against the second piston 30 and the cut valve 32 when pushed up and pushed down by the pressure in the second cylinder chamber 39 . An inverted T-shaped second air vent passage 46 is formed in the upper part of the inner piston 41 so as to communicate the cut valve 32 and the atmospheric chamber 35.

The inner piston 41 is slidably fitted into the center hole 47 of the outer piston 42 fitted into the second cylinder chamber 39, and has a stepped portion 48 on the outer periphery of the middle portion that engages with the upper edge of the center hole 47. It is formed. A compression spring 49 is interposed between the septum 38 and the outer piston 42 in the second cylinder chamber 39 in a stored force state, and the biasing force of the compression spring 49 is such that the internal pressure of the second cylinder chamber 39 is below a set value. Outa when it becomes.

- It is set to push down the stone 42 against the inner piston 41 (details will become clear in the explanation of the action).

A detour path 50 is formed in the upper part of the main body 11 so as to bypass the air supply port 22a formed in the valve plate 22 and communicate the inflow path 15 and the outflow path 16. A check valve chamber 51 is formed. Check valve chamber 51
The check valve 52 is biased by the compression spring 53, and the plug 54
The check valve 52 allows flow only in the direction from the outflow path 16 to the inflow path 15.

Next, the action will be explained.

1 Operation of the load detection device The air suspension pressure introduced into the second cylinder chamber 39 is controlled by the inner piston 41. The compression spring 49 acts on the outer piston 42 in the opposite direction to the air suspension pressure. That is, the force generated by the air suspension pressure acting on the effective area of the inner piston 41 and the outer piston 42 minus the force of the spring 49 acts on the first piston 14 via the second piston 30.

Here, since the force of the compression spring 49 in the balance state described later is constant, the higher the air suspension pressure, the greater the force acting on the first piston 14.In other words, as described above, the vehicle load and air suspension pressure are Proportionally, the larger the live load, the higher the air suspension pressure. Therefore, as the load increases, the force acting on the first piston 14 becomes stronger.

In this way, by detecting the vehicle's live load as a force acting on the second piston 14, the LSPV characteristics are created to match the characteristics of the vehicle, but the relationship between the air suspension pressure and the split point varies for each vehicle. Therefore, characteristic lines a, b, and c as shown in FIG. 5 are considered necessary.

By appropriately selecting the effective areas of the inner piston 41 and outer piston 42 in the control piston 40 and the force of the compression spring 49, all of these characteristics can be satisfied.〇Structure in the LSPV according to the non-embodiment satisfies the relationship shown by the straight line in FIG. In that case, a compression spring may be set below the outer piston 42.

11 Normal Provisioning Wl In any braking state, as described above, a force corresponding to the load at that time acts on the first piston 14, so the operation will be explained assuming that this is constant.

The pressure from the inlet passage 15 (hereinafter sometimes referred to as inlet pressure P1) is applied to the passage 21. Passing through the air supply port 22a, the outflow path 1
6 is sent out. At this time, the first piston 14 is gradually pushed down when the pressure acting on the effective area of the small diameter portion overcomes the upward force caused by the air suspension pressure. Then, when the air supply valve 1ffi24 comes into contact with the supply/exhaust valve 25.

The supply to the inflow path 15 and the outflow path 16 is also cut off.

This point becomes the split point. From this state,
Furthermore, when the inlet pressure Pi increases, the piston 14 is pushed up and the air supply valve seat 24 opens.

Pressure is again supplied from the inflow path 15 to the outflow path 16. As a result, when a pressure corresponding to the ratio between the large diameter lower effective area and the upper effective area of the piston 14 is supplied, the piston 1
4 is pushed down again to close the air supply valve seat 24 (this is called a balanced state in which both the air supply valve seat 24 and the exhaust valve seat 19 are closed; see the third position).

From this state, as the inlet pressure Pi increases, the pressure in the outflow passage 16 (hereinafter sometimes referred to as the outlet pressure Po) increases at a predetermined pressure reduction ratio with respect to the inlet pressure Pi (see Fig. 4). reference).

Further, when the inlet pressure Pi is lowered from the balanced state, the first piston 14 is pushed down together with the supply/exhaust valve 25, the exhaust valve seat 19 is opened (see Fig. 3 (81), and the outlet pressure P
Since O is exhausted, the original balance state is restored. As a result, the outlet pressure PO is lowered at a predetermined pressure reduction ratio with respect to the inlet pressure Pi.

Note that when the air suspension pressure changes in accordance with the load, as mentioned above, the force acting upward on the first piston 14 changes accordingly, so a corresponding split point is created, and as shown in Fig. 4. Obtain each characteristic line as shown.

By the way, as the inlet pressure Pi is lowered, the outlet pressure PO
is gradually lowered, but even when the inlet pressure becomes Pi#''-O, the outlet pressure Po, which balances only the force acting upward on the first piston 14, remains on the 1°6 side of the outflow path.

In order to prevent this, a check valve 52 is provided, and when the inlet pressure Pi is below the split point, the inlet pressure Pi and the outlet pressure Po are reduced at a ratio of 1:1. That is, during pressure reduction, since the inlet pressure Pi is acting on the check valve chamber 52, the check valve 52 closes the outlet due to the force caused by the difference between the inlet pressure P1 and the outlet pressure po and the force of the compression spring 53. 16 is closed, but the inlet pressure Pi
When the outlet pressure Po becomes higher, the check valve 52 opens and the outlet pressure Po flows backward, so that the pressure on the outflow path 16 side decreases. Due to this action, the balance state in the first piston 14 is disrupted, the first piston 14 is pushed up, the intake valve seat 24 is opened, and the initial state is returned, and the inlet pressure PI and outlet pressure PO become 1:1. .

(Operation at the time of 11 fail (see Fig. 3 fcl)).

When the linear suspension pressure becomes 0 compared to the damage pressure of piping in the air suspension, the outer piston 42 is pushed down by the compression spring 49. At the same time, the cut valve 32 and the inner piston 41 are pushed down by the compression spring 34,
Since the seat portion of the cut valve 32 contacts the second piston 3o, the back pressure chamber 31 is blocked from the air vent path 33. Also,
The cut valve holder 28 is also pushed down by the inlet pressure Pi and the spring 27, and the seat portion of the back pressure introduction valve 26 opens.
Inlet pressure Pi is introduced into the back pressure chamber 31 through the back pressure introduction path 29. Since this introduction pressure acts on the back surface of the first piston 14, the ratio of the effective i products of the upper surface and the lower surface of the first piston 14 is approximately 1:1. Therefore, the ratio between the inlet pressure Pi and the outlet pressure PO is also 1:1.

l111 Operation when the air suspension pressure is low. If the control piston 4o has an integral structure, the compression spring 49
The depressurizing action is canceled by simply pushing the outer piston 42 down to the balanced position.

- If the air suspension side is normal, depressurization is necessary even if the air suspension pressure is low.

Therefore, by configuring the control piston 4o in a divided structure with an inner piston 41 and an outer histone 42, even if the outer piston 42 is pushed down, the air suspension pressure acting on the inner piston 41 causes the first piston 14 to The pressure can be applied to reduce the pressure in the same way as under normal conditions.

According to this embodiment, since the load sensing proportioning function can be demonstrated using air suspension pressure, the structure can be simplified and wear and tear in the link material structure can be reduced.
The risk of failure and malfunction is eliminated, and it is economically advantageous.

Since the control 61 piston that receives the air suspension pressure has a double structure, it is possible to ensure the necessary novation function even when the air suspension pressure is low.

The differential piston that operates to close the passage between the inflow path and the outflow path has a composite structure of a first piston and a second piston, and in an unexpected situation where the air suspension pressure becomes O, the pressure in the inflow path is By introducing the air into the back of the piston, it is possible to leave the air supply port between the inflow and outflow channels open and stop the decompression operation, which is a braking force distribution function, so that it can be used in case of unexpected situations. Concerns about insufficient braking power can be eliminated and safety can be ensured.

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.

For example, the composite structure of the control piston is not limited to a double structure, and any structure may be used as long as one of the pistons cooperates with the operating piston except in the case of fail-safe. Furthermore, the control piston may be of monolithic construction.

As described above, according to the present invention, the braking force can be distributed according to the vehicle load using the air suspension pressure.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing an LSPV that is an embodiment of the present invention, Fig. 2 is a schematic circuit diagram showing air brake equipment using the same, and Fig. 3 is a vertical cross-sectional view showing an LSPV that is an embodiment of the present invention.
E is a schematic sectional view for explaining the action, and FIGS. 4 and 5 are line diagrams. 1...Air conditioner brake two y22...Air tank, 3
...Bregie valve, 4...Front brake chamber, 5°° quick release valve, 6...Rear brake chamber, 7...Relay pulp, 8...L
SPV, 9... Air suspension, 11... Main body, 12... First cylinder chamber (differential cylinder chamber), 13
・Par differential piston, 14... 1st piston, 15...
・Inflow path, 16... Outflow path, 17... Exhaust path, 18
°° Filter, 19...Exhaust valve seat, 2o...Valve chamber,
, 21... passage, 22... pulp plate, 22a
...Air supply port, 23 - Retaining ring. 24... Air supply valve seat, 25... Supply and exhaust valve, 26...
Back pressure introduction valve, 27... compression spring, 28... cut valve holder. 29...Back pressure introduction path, 3o...Second piston, 31
...Back pressure chamber, 32...Cut valve, 33...Air vent path, fitting...Compression spring, 35...Atmospheric chamber, 36...
・Air passage, 31... Filter, 38... Partition wall, 39
...Second cylinder chamber (control cylinder), 40...
Control piston, 41,... Inner piston, 42...
Outer piston, 43...Vent hole, 44...Near suspension pressure introduction path, 45...Central hole, 46...Air vent path, 47...Central hole, 48...Step part, 49...・Compression spring, 50...Detour, 52...Reverse valve・Patent applicant: Miwa Seiki Co., Ltd. Agent: Tatsuya Kajihara

Claims (1)

[Claims] (1) A differential cylinder chamber in which an inflow path and an outflow path are established, a differential piston that is installed in this cylinder chamber and reciprocates in response to the pressure in the inflow path, and the inflow path and outflow path. A normally open pulp is formed in a passage between the cylinders and is closed by the reciprocating movement of the differential piston, a control cylinder chamber into which the pressure of the vehicle's suspension is introduced, and a control cylinder chamber which is installed in this cylinder chamber and which is closed by the reciprocating motion of the differential piston. and a control piston that biases the pulp in the direction of pulp opening.