JP3046122B2 - Relief valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relief valve provided in a hydraulic circuit or the like. More specifically, the present invention relates to an improvement of a balance piston type relief valve having a shockless function suitable for equipping a hydraulic circuit including a brake circuit.

[0002]

2. Description of the Related Art Generally, when a surge pressure is generated, a relief valve has a time delay from the generation of the surge pressure until the control is stabilized, that is, an operation delay. Therefore, it is considered that it is absolutely necessary to reduce the surge pressure in order to improve the characteristics of the relief valve. A conventional direct acting relief valve as shown in FIG. 4 is conventionally known as a device for cutting a surge pressure.

[0003] This direct acting relief valve is a casing 1
Are provided with first and second outflow / inflow ports 50 and 51. A poppet 3 is slidably provided in a sleeve 2 provided in the casing 1. A poppet sheet member 4 is fitted concentrically with the sleeve 2 in the lower portion of the sleeve 2 in the drawing. Further, in the upper portion in the figure in the Keshin'ngu 1, the plug 5 is screwed. This case 1
And a plug 5 together with the plug 5 inside the sleeve 2 provided inside the casing 1 and on the opposite side of the poppet sheet member 4. This spring chamber 6
A spring 7 is provided therein, and the poppet 3 is pressed against the poppet sheet member 4 by the force of the spring 7. Further, an orifice 8 is formed in the poppet 3 for communicating the first inflow / outflow port 50 side with the spring chamber 6. Also, by reducing the diameter D ₂ of the shaft portion 3a of the poppet 3 the diameter D ₁ of the poppet seat member 4 of the seat portion 18. Reference numeral 12 denotes a spring seat.

A sliding space 13 is provided on the outer periphery of the sleeve 2 on the plug 5 side. The sliding space 13 and the annular groove 10 provided on the outer periphery of the sleeve 2 communicate with each other by an annular passage 14 formed on the outer periphery of the sleeve 2. A ring-shaped free piston 15 that slides on the outer periphery of the sleeve 2 is provided in the sliding space 13. This free piston 15 also slides on the casing 1 side,
The inside of the sliding space 13 moves up and down in the figure. Further, a small hole 16 communicating the spring chamber 6 and the sliding space 13 is provided in the sleeve 2. The sleeve 2 has an annular groove 10.
There is provided a communication hole 17 for communicating between the inside of the sleeve 2 and the inside. The space 9 communicates with the annular groove 10 through the small hole 11.
are doing. In addition, the annular groove 10 has the second inflow / outflow port 51.
Is in communication with

[0005] The conventional direct acting relief valve configured as described above operates as follows to perform a relief operation and a surge pressure cut. That is, the pressure of the fluid flowing from the first inflow / outflow port 50 acts on the poppet 3 pressed against the poppet sheet member 4 by the force of the spring 7 and also acts on the spring chamber 6 via the orifice 8. In this case, if the pressure acting on the poppet 3 is higher than the relief set pressure by the spring 7, the poppet 3 is pushed up against the force of the spring 7 and the first inflow / outflow port 50 and the second inflow / outflow port 51 are connected. Communication and a relief operation are performed.

At the time of such a relief operation, the fluid in the spring chamber 6 flows into the sliding space 13 from the small hole 16 and applies the pressure to the free piston 15 located on the plug 5 side. Thereby, the free piston 15 slides in the sliding space 13 in the downward direction in the figure. The movement of the free piston 15 causes a volume change in the sliding space 13 to cut the surge pressure. In addition, a flow occurs in the spring chamber 6 due to this volume change, and a pressure difference occurs around the orifice 8 . The opening degree of the seat portion 18 of the poppet sheet member 4 is determined by the pressure difference, the cross-sectional area based on the diameters D ₁ and D _2, and the spring force of the spring 7. In addition, around the small hole 16
A differential pressure is also generated. In this way, the movement of the free piston 15 changes the volume of the sliding space 13 to cut the surge pressure and open the poppet 3.

[0007]

In the conventional apparatus as described above, the surge pressure can be cut, but since it is a direct-acting type, there is a problem that its override characteristics are not good. If you try to improve this override characteristic,
A balance piston type relief valve may be used. However, since the structure of the balance piston type relief valve is complicated, a free piston cannot be easily provided like a direct acting type relief valve. For this reason, conventionally, there has been a problem that a relief valve that can simultaneously solve the two problems of improving the override characteristics while cutting the surge pressure to prevent an operation delay cannot be used.

In this conventional relief valve, the free piston 15 cannot be returned to the original position shown in the drawing unless the pressure at the second inflow / outflow port 51 increases. If the free piston 15 is stopped at a position completely opposite to the original position shown in the drawing, there is a problem that the function of cutting the surge pressure is not exhibited at all. An object of the present invention is to provide a relief valve in which a free piston can be easily provided even in a relief valve of the balance piston type.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a sleeve is provided on a casing formed with first and second inflow / outflow ports, and a cylindrical valve member is provided inside the sleeve. An orifice is formed in the hollow portion of the valve member, a pilot seat member is fitted on the anti-orifice side of the sleeve, and a sub-casing is formed by the sleeve and the pilot seat member. And a pilot spring interposed between the valve member and the pilot seat member for applying a force in the valve closing direction to the valve member. The direction in which the pilot sheet of the member is opened and closed by the pilot poppet and the pilot poppet is pressed against the pilot sheet. A second spring for applying a force, the spring force of the second spring being greater than the spring force of the first spring, and the orifice communicating with the pilot seat via a hollow portion of the valve member; A movable piston is slidably provided in the sliding space.
Communicates via a passage provided with a counter-scan pulling side pilot seat in member in the hollow portion and the sliding space of the valve member, passage 42 the fluid passes through the pilot seat, formed in the pilot seat in the member Through the annular space formed around the sleeve via the sliding space, and communicate with the second inflow / outflow port.

[0010]

With the above construction, when no pressure is generated in any of the first and second inflow / outflow ports, the valve member is closed by the action of the first and second springs. When the pressure at the first inflow / outflow port rises from this state, pressure acts on the sliding space communicating with the hollow portion of the valve member and the pilot seat member, and the moving piston in the sliding space moves downward in the drawing. I do. This movement of the moving piston changes the volume of the sliding space, and causes the orifice formed on the valve member to
Passage 4 provided in the pilot seat member from the fist
0, a flow occurs in the sliding space, and the valve member is opened.
And reduce surge pressure in the circuit.

The pressure at the first outflow / inflow port is equal to the second pressure.
When the pressure exceeds the set pressure determined by the spring, the pilot poppet opens. When the pilot poppet opens, fluid from the first inflow / outflow port flows from the orifice formed in the valve member through the annular passage formed around the sleeve through the passage in the pilot seat member to the second inflow / outflow port. leak. Thus, the differential pressure across the orifice
At the position where the first spring force and the fluid force are balanced.
The opening is determined.

[0012]

1 to 3 show an embodiment of the present invention. The same reference numerals are used for the same components as in the conventional example, and the detailed description is omitted.

FIG. 1 shows a first embodiment.

In this embodiment, a first inflow / outflow port 50 provided on the lower side of the drawing and a second inflow / outflow port 51 provided on the upper side of the drawing are provided inside the casing 1.
The mounting groove 19 is shown in the vertical direction in the figure so as to communicate with the second inflow / outflow ports 50 and 51. Each part described later is mounted in the mounting groove 19.

The mounting groove 19 communicates with the first inflow / outflow port 50 at the lower end of the drawing, and the casing 1 at the upper end.
Of the second outflow / inflow port 5
It communicates with 1. The mounting groove 19 is provided on the first step portion 2 provided near the first inflow / outflow port 50 from below in the figure.
0, a large annular groove 21 provided in communication with the second inflow / outflow port 51, and a small annular groove 2 provided close to the large annular groove 21.
2, a second step 23 provided close to the small annular groove 22, and a screw portion 24 provided around an opening for opening the casing 1 to the outside.

Each of the sleeve 25, the valve member 26, the first spring 27, the pilot seat member 28, the moving piston 29, the pilot poppet 30, the second spring 31, and the plug 5 are mounted on the mounting groove 19 as described above. It is designed to be mounted and assembled in this order.

The sleeve 25 is fitted and mounted in the mounting groove 19 such that the lower end in the figure contacts the first step portion 20 and the upper end projects upward from the second step 23. By fitting the sleeve 25 into the mounting groove 19 in this manner, the large annular groove 21
Is an annular passage 32 and the small annular groove 22 is an annular passage 33. A pilot seat member 28 is fitted on the plug 5 side of the sleeve 25. The sleeve 25 and the pilot seat member 28 constitute a sub casing 52. The space formed between the sub-casing 52 and the casing 1 is the sliding space 39. In addition, the first inflow / outflow port 5 is provided in the annular passage 32.
The communication hole 34 that communicates with the first port 0 and the second inflow / outflow port 51 is opened. A main sheet 35 is formed inside the sleeve 25.

The valve member 26 is slidably provided in the sleeve 25. This valve member 26 is hollow,
An orifice 37 that connects the hollow portion 36 to the main sheet 35 is formed.

The first spring 27 is connected to the hollow portion 36.
The force is applied in a direction in which the valve member 26 is pressed against the main seat 35. In addition, this split
When the same pressure acts on the main seat 35 side and the hollow portion 36 side by the oscillating force , the valve member 26 closes the main seat 35.

The pilot seat member 28 is a sleeve 2
5 and the plug 5, and receives a spring force from the first spring 27. The pilot seat member 28 is provided with a hollow portion 36 of the valve member 26 in the axial direction of the central portion.
An orifice 38 is provided in communication with the orifice. The pilot seat member 28 has a passage 40 communicating the hollow portion 36 with the sliding space 39 and a pilot seat 4.
1 is provided with a passage 42 which communicates the outflow side with the annular passage 33.

The moving piston 29 is slidably provided in the sliding space 39. The moving piston 29 shown is always pushed by a spring 43 in a direction to return to the original position, but this spring is not necessarily required.
There is no.

A pilot poppet 30 is provided in a second spring chamber 44 formed in the plug 5.
1 presses against the pilot seat member 28.
The plug 5 is fitted into the pilot seat member 28 and screwed into the casing 1.

In this embodiment, a pilot seat 41 and an annular passage 3 are provided between the casing 1 and the sleeve 25.
A pilot passage composed of 2, 33 is formed. Since the pilot passage is formed in this manner, strict precision concentricity between the casing 1 and the sleeve 25 is not required. Further, since the valve member 26 is in pressure contact with the main seat 35 in the sleeve 25, the concentricity of the two is not impaired. As described above, since it is not necessary to process each component member with strict precision concentricity as compared with the conventional linear motion type, the manufacturing process does not require much labor and the productivity is improved.

In this embodiment, the pressure fluid flowing into the hollow portion 36 from the first inflow / outflow port 50 through the orifice 37 of the valve member 26 is applied to the pilot seat member 28.
Of the moving piston 2 in the sliding space 39
9 is slid downward in the figure. The moving piston 2
9 performs the same operation as the free piston 15 of the conventional example, thereby exhibiting a shockless function of cutting the surge pressure. When the spring 43 is provided, the moving piston 29 is always returned to the original position. Therefore, the position of the moving piston 29 is influenced by the pressure level of the second inflow / outflow port 51 as in the conventional free piston 15. Absent. The first stage of the shockless operation of this embodiment ends when the moving piston 29 hits the lower end of the sliding space 39.

The relief operation is performed as follows. That is, the pressure on the first inflow / outflow port 50 side is equal to the second
When the pressure rises above the relief pressure set by the spring 31,
The pilot poppet 30 moves against the force of the second spring 31. Thereby, the pilot seat 41 is opened. The pressure fluid flowing out from the opened pilot seat 41 flows out to the second inflow / outflow port 51 via the passage 42 and the annular passages 32 and 33. As a result, a flow is generated in the hollow portion 36 of the valve member 26, and a differential pressure is generated across the orifice of the valve member 26. Due to this differential pressure, the valve member 26 opens the main seat 35 against the force of the first spring 27, and connects the first inflow / outflow port 50 and the relief B. Thus, the relief operation is performed.

It is well known that such a balance piston type relief valve has a better override characteristic than a direct acting type. According to the present invention, since the balance piston type is provided with a shockless function, the relief characteristics are good, and at the same time, the surge pressure can be cut, and the operation delay can be eliminated.

FIG. 2 shows a second embodiment of the present invention.

In this embodiment, a recess 45 is formed downstream of the orifice 37 of the valve member 26, and a small hole 46 is formed in the recess 45.
Is used. This is because the first inflow / outflow port 50 and the second inflow / outflow port 51 are not opened and closed by the seat portion of the valve member 26 and the main seat 35 as in the first embodiment, but by the movement of the valve member 26. The communication between the small hole 46 and the communication hole 34 is opened and closed.

FIG. 3 shows a third embodiment of the present invention.

In this embodiment, a spring seat 47, a lock nut 48, and an adjusting screw 49 are provided for the second spring 31, and the set load of the second spring 31 is variably adjusted, so that the properties of the pressure fluid and the equipment to be provided are provided. An appropriate spring load corresponding to the hydraulic circuit can be set.

[0031]

According to the relief valve of the present invention, a mechanism for cutting the surge pressure can be adopted in the balance piston type, so that the surge pressure can be absorbed and the operation delay can be prevented while improving the override characteristics. That is, the improvement of both characteristics, which could not be achieved conventionally, can be achieved at the same time. Also,
Even if the pressure at the second outflow / inflow port side does not rise, the moving piston
If a spring is provided at the lower end of the ton ,
Since the moving piston can be returned to its original position, surge pressure can be reliably reduced under any circumstances.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a sectional view showing a main part of a second embodiment.

FIG. 3 is a sectional view showing a main part of a third embodiment.

FIG. 4 is a sectional view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 casing 25 sleeve 26 valve member 27 first spring 28 pilot seat member 29 moving piston 30 pilot poppet 31 second spring 32 annular passage 33 annular passage 36 hollow portion 37 orifice 39 sliding space 40 passage 41 pilot seat 43 spring 50 first Outflow port 51 Second outflow port 52 Sub casing

Continuation of the front page (56) References JP-A-58-207585 (JP, A) JP-A-57-208371 (JP, A) JP-A-64-12183 (JP, A) JP-A-63-97768 (JP) , U) JP 3-79593 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16K 17/00-17/30 F16K 31/12-31/165

Claims (1)

(57) [Claims] A sleeve is provided in a casing having first and second inflow / outflow ports formed therein, a cylindrical valve member is provided inside the sleeve, and an orifice is formed in a hollow portion of the valve member. A pilot seat member is fitted to the anti-orifice side of the sub-casing, the sleeve and the pilot seat member constitute a sub-casing, and a space formed between the sub-casing and the casing is used as a sliding space. A first spring for applying a force in a valve closing direction to the valve member is interposed between the valve member and the pilot seat member, and the pilot seat of the pilot seat member is opened and closed by a pilot poppet. A second spring for applying a force in the direction of pressing against the pilot seat,
The spring force of the second spring is made larger than the spring force of the first spring, and the orifice communicates with the pilot seat via the hollow portion of the valve member, so that the movable piston can slide in the sliding space. to provided further communicates through a passage provided with a counter-scan pulling side pilot seat in member in the hollow portion and the sliding space of the valve member, fluid passing through the pilot seat, the pilot seat member A relief valve configured to pass through an annular passage formed around the sleeve via the sliding space via the passage formed in the above, and communicate with the second inflow / outflow port.