JP2008248927A - Relief valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relief valve having stable relief characteristics regardless of the specifications of a hydraulic circuit. <P>SOLUTION: This relief valve comprises: a valve 12 and a piston 13 housed in a casing 11 and reciprocatingly movable in the axial direction; and a spring 14 for pressing the valve 12 and the piston 13 in the directions opposite to each other. When the hydraulic pressure at a high-pressure port 111a is higher than a predetermined one, it is vent to prevent the hydraulic pressure in the hydraulic circuit 21 from rising to more than the predetermined pressure. The high-pressure port 111a communicated with a spring chamber 16 through a vertical through passage 12b formed in a valve 12. A damper chamber 17 communicates with the spring chamber 16 through a vertical through passage 13c formed in the piston 13. A piston stroke chamber 18 communicates with a drain circuit 22 through a pressure introducing passage 111c formed in the casing 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a relief valve for preventing the hydraulic pressure of a hydraulic circuit from becoming higher than a predetermined pressure.

  Conventionally, various relief valves that are used in hydraulic circuits such as hydraulic working machines and prevent the hydraulic pressure from rising above a predetermined pressure have been proposed (for example, Patent Document 1). The relief valve disclosed in Patent Document 1 will be described with reference to FIG.

  In the relief valve 10 of Patent Document 1, a valve 12, a piston 13, and a spring 14 are accommodated in a casing 11.

  The casing 11 is formed with a high pressure port 11a and a low pressure port 11b. The high pressure port 11a is connected to a hydraulic circuit 21 such as a hydraulic working machine, and high pressure oil pressure is guided. The low-pressure port 11 b is connected to a drain circuit 22.

  The valve 12 is movable in the axial direction. A hole 12 a is formed near the tip of the valve 12. The valve 12 closes the high-pressure port 11a when the hydraulic pressure of the high-pressure port 11a is lower than a predetermined pressure, and retracts when the hydraulic pressure of the high-pressure port 11a becomes higher than the predetermined pressure, thereby moving the high-pressure port 11a to the low-pressure port 11b. By communicating, the hydraulic pressure of the high-pressure port 11a is released.

  The piston 13 inserts the rod portion 13 a formed at the tip into the valve 12. The piston 13 vertically penetrates in the axial direction and has a longitudinal through passage 13c capable of guiding the hydraulic pressure of the high-pressure port 11a in a damper chamber 17 formed in the bottom portion 13b. A plurality of perforated plugs 15 having pores (orifices) are attached to the bottom of the vertical through passage 13c. In FIG. 2, four plugs 15 with holes are attached.

  The spring 14 is interposed between the valve 12 and the piston 13. The valve 12 and the piston 13 are pressed in opposite directions by the spring 14.

  The hydraulic pressure of the high-pressure port 11a is guided to the damper chamber 17 through the hole 12a of the valve 12 and the vertical through passage 13c (plug 15 with a hole) of the piston 13. As the hydraulic pressure in the damper chamber 17 increases, the piston 13 moves in the valve direction (the right direction in FIG. 2). Then, since the spring 14 is compressed, the relief pressure of the valve 12 increases.

In such a relief valve 10, the spring chamber 16 is filled with oil, and when the valve 12 or the piston 13 moves to reduce the volume of the spring chamber 16, the oil is a hole provided in the casing 11. It is released to the drain circuit 22 through 11c. When the valve 12 or the piston 13 is moved and the volume of the spring chamber 16 is increased, the oil is replenished from the drain circuit 22 through the hole 11c.
JP 2006-153040 A

  However, in the conventional relief valve 10 described above, since the hydraulic pressure in the drain circuit is applied to the spring chamber 16, the relief pressure may differ depending on the specifications of the hydraulic circuit that uses the relief valve 10. That is, the total length and shape of the drain circuit 22 depend on the specifications of the hydraulic circuit. Therefore, the pressure loss in the drain circuit 22 varies depending on the specifications of the hydraulic circuit, and the hydraulic pressure in the drain circuit also varies depending on the specifications of the hydraulic circuit. When such hydraulic pressure is applied to the spring chamber 16, the relief pressure of the valve 12 is affected.

  The present invention has been made paying attention to such conventional problems, and an object of the present invention is to provide a relief valve capable of obtaining a stable relief characteristic regardless of the specifications of the hydraulic circuit.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention provides a casing (11) including a high pressure port (111a) connected to a hydraulic circuit (21) and a low pressure port (111b) connected to a drain circuit (22), and the casing (11). A valve (12) and a piston (13) which are accommodated and reciprocally movable in the axial direction, and are interposed between the valve (12) and the piston (13), and the valve (12) and the piston (13) A spring (14) that presses in opposite directions, and the valve (12) closes the high-pressure port (111a) when the hydraulic pressure of the high-pressure port (111a) is lower than a predetermined pressure. When the hydraulic pressure of the port (111a) becomes higher than a predetermined pressure, the hydraulic pressure of the hydraulic circuit (21) is released by connecting the high pressure port (111a) to the low pressure port (111b) to release the hydraulic pressure of the high pressure port (111a). That the pressure is higher than the specified pressure A relief valve that stops, a spring chamber (16) defined by the casing (11), the valve (12), and the piston (13), and a bottom portion of the piston (13) ( 13b) and a damper chamber (17) defined by the casing (11), and a piston stroke chamber (18) defined by the piston (13) and the casing (11), The high-pressure port (111a) communicates with the spring chamber (16) via a vertical through passage (12b) formed in the valve (12), and the damper chamber (17) is formed in the piston (13). The piston stroke chamber (18) communicates with the spring chamber (16) through the vertical through passage (13c), and the drain circuit (111c) is formed in the casing (11) through the drain circuit (111c). 22) To.

  According to the present invention, the high-pressure port is communicated with the spring chamber defined by the casing, the valve, and the piston via the valve vertical passage, and the spring chamber is defined by the piston bottom and the casing. It communicates with the damper chamber via a piston longitudinal through passage. The piston stroke chamber defined by the piston and the casing is communicated with the drain circuit via a pressure guide passage formed in the casing. Because of such a configuration, the hydraulic pressure in the drain circuit is not directly applied to the valve. Therefore, a stable relief characteristic can be obtained regardless of the specifications of the drain circuit.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view showing an embodiment of a relief valve according to the present invention.

  In the relief valve 10 of the present invention, a valve 12, a piston 13, and a spring 14 are accommodated in a casing 11.

  The casing 11 includes a casing body 111 and a casing cap 112.

  The casing body 111 is formed with a high pressure port 111a and a low pressure port 111b. The high pressure port 111a is connected to a hydraulic circuit 21 such as a hydraulic working machine, and high pressure oil pressure is guided. The low pressure port 111 b is connected to the drain circuit 22.

  The valve 12 is housed on the front end side of the casing body 111 and can reciprocate in the axial direction. A hole 12 a is formed near the tip of the valve 12. A vertical through passage 12 b is formed in the valve 12. The valve 12 closes the high pressure port 11a when the hydraulic pressure of the high pressure port 11a is lower than a predetermined pressure, and communicates the high pressure port 11a with the low pressure port 11b when the hydraulic pressure of the high pressure port 11a becomes higher than the predetermined pressure. The hydraulic pressure of the high pressure port 11a is released.

  The piston 13 is housed in the casing body 111 and can reciprocate in the axial direction until the stopper surface 13 d abuts against the inner wall 111 d of the casing body 111. The piston 13 is separated from the valve 12. The piston 13 is formed with a longitudinal through passage 13c that penetrates in the axial direction and can guide the hydraulic pressure of the spring chamber 16 in a damper chamber 17 formed in the bottom portion 13b. A plurality of perforated plugs 15 having pores (orifices) are attached to the bottom of the vertical through passage 13c. In FIG. 1, two plugs 15 with holes are attached.

  The spring 14 is interposed between the valve 12 and the piston 13 and presses the valve 12 and the piston 13 in opposite directions.

  The spring chamber 16 is defined by the casing 11 (casing body 111), the valve 12, and the piston 13. The spring 14 is disposed in the spring chamber 16.

  The damper chamber 17 is defined by the bottom portion 13b of the piston 13 and the casing 11 (the casing body 111 and the casing cap 112).

  The piston stroke chamber 18 is defined by the piston 13 and the casing 11 (casing body 111). The piston stroke chamber 18 is independent from the spring chamber 16. The piston stroke chamber 18 is connected to the drain circuit 22 via the pressure guiding passage 111c.

  The pressure receiving area A2 facing the damper chamber 17 is larger than the pressure receiving area A1 facing the spring chamber 16 of the piston 13. Further, the pressure receiving area A3 facing the piston stroke chamber 18 is an area obtained by subtracting A1 from A2, that is, A3 = A2-A1. When the valve 12 is opened, the oil in the spring chamber 16 is removed through the hole 12 a of the valve 12.

  When the hydraulic pressure of the hydraulic circuit 21 changes, the pressure is introduced to the spring chamber 16 through the high pressure port 111a of the casing body 111 and the hole 12a of the valve 12, and further the damper chamber through the longitudinal through passage 13c of the piston 13 and the plug 15 with the hole. 17 is introduced. When the pressure in the damper chamber 17 increases, the piston 13 moves to the right in FIG. 1, and when the pressure in the damper chamber 17 decreases, the piston 13 moves to the left in FIG. Then, the load at which the spring 14 is expanded and contracted and the valve 12 starts a stroke changes. When the hydraulic pressure in the hydraulic circuit 21 suddenly rises and exceeds the stroke start load of the valve 12, the valve 12 moves to the left in FIG. 1 to connect the high pressure port 11a to the low pressure port 11b to release the hydraulic pressure of the high pressure port 11a. . That is, the high pressure port pressure can be adjusted according to the stroke start load. The characteristic at the time of relief (relief delay characteristic with respect to hydraulic pressure rise) can be adjusted by the diameter of the hole 12a of the valve 12 and the diameter and quantity of the plug 15 with the hole. The plug 15 with a hole is screwed into the vertical through passage 13c of the piston 13, and can be replaced with one having a different hole diameter, and the quantity can be adjusted.

  By the way, in the conventional relief valve 10, since the hydraulic pressure in the drain circuit is applied to the spring chamber 16 as described above, there is a possibility that the relief pressure differs depending on the specifications of the hydraulic circuit using the relief valve 10. That is, the total length and shape of the drain circuit 22 depend on the specifications of the hydraulic circuit. Therefore, the pressure loss in the drain circuit 22 varies depending on the specifications of the hydraulic circuit, and the hydraulic pressure in the drain circuit also varies depending on the specifications of the hydraulic circuit. When such hydraulic pressure is applied to the spring chamber 16, the relief pressure of the valve 12 (high pressure port opening start pressure) is affected.

  Therefore, in the present invention, the hydraulic pressure in the drain circuit is not applied to the spring chamber 16. Specifically, the piston stroke chamber 18 formed independently of the spring chamber 16 is communicated with the drain circuit 22 through a passage vertically extending through the casing 11 (casing body 111).

  Thus, conventionally, since the hydraulic pressure in the drain circuit is also applied to the valve 12, the relief pressure of the valve 12 (high pressure port opening start pressure) is affected. Therefore, the change in the relief pressure due to the specifications of the hydraulic circuit can be reduced, and a stable relief characteristic can be obtained.

  Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is obvious that these are also included in the technical scope of the present invention.

It is sectional drawing which shows one Embodiment of the relief valve by this invention. It is sectional drawing which shows an example of the conventional relief valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Relief valve 11 Casing 111 Casing body 112 Casing cap 11a, 111a High pressure port 11b, 111b Low pressure port 11c Hole 111c Induction pressure passage 12 Valve 13 Piston 14 Spring 15 Plug with hole 16 Spring chamber 17 Damper chamber 18 Piston stroke chamber 21 Hydraulic circuit 22 Drain circuit

Claims (3)

A casing including a high pressure port connected to the hydraulic circuit and a low pressure port connected to the drain circuit;
A valve and a piston housed in the casing and capable of reciprocating in the axial direction;
A spring interposed between the valve and the piston and pressing the valve and the piston in opposite directions;
With
The valve closes the high pressure port when the hydraulic pressure of the high pressure port is lower than a predetermined pressure, and connects the high pressure port to the low pressure port when the hydraulic pressure of the high pressure port becomes higher than the predetermined pressure. A relief valve for preventing the hydraulic pressure of the hydraulic circuit from becoming higher than a predetermined pressure by releasing the hydraulic pressure of
A spring chamber defined by the casing, the valve, and the piston, and housing the spring;
A damper chamber defined by the bottom of the piston and the casing;
A piston stroke chamber defined by the piston and the casing;
Have
The high-pressure port communicates with the spring chamber via a vertical through passage formed in the valve,
The damper chamber is communicated with the spring chamber via a longitudinal passage formed in the piston,
The piston stroke chamber communicates with a drain circuit via a pressure guiding passage formed in the casing.
Relief valve characterized by that. The piston is a stepped piston having a large diameter portion facing the damper chamber and a small diameter portion facing the spring chamber.
The relief valve according to claim 1. The piston stroke chamber shrinks as the piston moves the spring in the compression direction;
The relief valve according to claim 1 or 2, characterized by the above.