Valve device

Abstract

To reduce the number of components of a valve device.SOLUTION: A valve device 100 includes: a storage hole 14 which is formed in a housing 10; and pilot check valves 4a, 4b which are stored in the storage hole 14, allow the flow of fluid from a tank port 13 to cylinder ports 12a, 12b, and inhibit the flow of the fluid from the cylinder ports 12a, 12b to the tank port 13. A valve element 41 of the pilot check valves 4a, 4b has a cylindrical body 41a, and a large diameter portion 41b having a dimeter larger than that of the body 41a, and fluid for opening the valve element 41 of the pilot check valves 4a, 4b is guided to a pilot pressure chamber 60 defined by the body 41a, the large diameter portion 41b, and an inner peripheral surface of the storage hole 14.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a valve device. [Background technology]

[0002] Patent Document 1 discloses a valve device equipped with a pilot check valve and an overload relief valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-283785 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the valve gear described in Patent Document 1, when pressure acts on the piston, the piston presses the valve body of the pilot check valve, forcibly opening the pilot check valve.

[0005] However, the valve device described in Patent Document 1 has a structure in which a piston presses the valve body of the pilot check valve, and therefore has a large number of parts.

[0006] The present invention has been made in consideration of the above problems, and has an object to reduce the number of parts of a valve device. [Means for solving the problem]

[0007] The present invention comprises a housing having a first port and a second port, an accommodating hole formed in the housing, and a pilot check valve accommodated in the accommodating hole and allowing fluid to flow from the first port to the second port while blocking fluid flow from the second port to the first port, wherein a valve element of the pilot check valve has a cylindrical main body and a large diameter portion larger in diameter than the main body, and fluid for opening the valve element of the pilot check valve is guided to a pilot pressure chamber defined by the main body, the large diameter portion, and the inner circumferential surface of the accommodating hole.

[0008] In this invention, a pilot pressure chamber, into which a fluid for forcibly opening the valve disc of the pilot check valve is introduced, is provided between the inner circumferential surface of the accommodation hole and the outer circumferential surface of the valve disc of the pilot check valve. This eliminates the need for a piston or other component for forcibly opening the valve disc of the pilot check valve, thereby reducing the number of components.

[0009] The present invention is also characterized in that it has a first seal member attached to the main body portion and sealing between the accommodating hole and the main body portion, and a second seal member attached to the large diameter portion and sealing between the accommodating hole and the main body portion, and the pilot pressure chamber is formed between the first seal member and the second seal member.

[0010] According to the present invention, leakage of the fluid guided to the pilot pressure chamber can be suppressed. Effect of the Invention

[0011] According to the present invention, the number of parts of the valve device can be reduced. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of a hydraulic circuit to which a valve device according to this embodiment is applied. [Diagram 2] FIG. 2 is a cross-sectional view of the valve device according to the present embodiment. [Diagram 3] FIG. 3 is an enlarged view of a main part of the valve device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A valve device 100 of the present invention will be described with reference to the drawings.

[0014] First, with reference to FIG. 1, a hydraulic circuit S to which a valve device 100 is applied will be described.

[0015] 1, the hydraulic circuit S is configured as a closed circuit and includes a pump 1, a cylinder 2, and a valve device 100. In the hydraulic circuit S, hydraulic oil is used as the working fluid. Instead of hydraulic oil, other non-compressible fluids may be used as the working fluid.

[0016] The pump 1 is driven by a drive source such as an electric motor (not shown) and is a swash plate type axial piston pump that is capable of discharging in both directions and has a variable displacement.

[0017] The cylinder 2 is a single-rod type fluid pressure cylinder. The cylinder 2 includes a piston 2b that slidably moves within a cylinder tube 2a, and a piston rod 2c that is connected to the piston 2b and protrudes to the outside of the cylinder tube 2a. The inside of the cylinder tube 2a is divided by the piston 2b into a rod side chamber 2d and a counter rod side chamber 2e.

[0018] The port 1a of the pump 1 and the rod side chamber 2d of the cylinder 2 are connected by a first passage 3a, and the port 1b of the pump 1 and the anti-rod side chamber 2e of the cylinder 2 are connected by a second passage 3b.

[0019] The valve device 100 includes a pilot check valve 4a provided in a flow path connecting the first passage 3a and the tank T, a pilot check valve 4b provided in a flow path connecting the second passage 3b and the tank T, a relief valve 5a that opens when the pressure in the first passage 3a becomes equal to or higher than a predetermined value P1 to discharge hydraulic oil from the first passage 3a to the tank T, and a relief valve 5b that opens when the pressure in the second passage 3b becomes equal to or higher than the predetermined value P1 to discharge hydraulic oil from the second passage 3b to the tank T.

[0020] The pilot check valve 4a allows the flow of hydraulic oil from the tank T to the first passage 3a, and prevents the flow of hydraulic oil from the first passage 3a to the tank T. In addition, the pilot check valve 4a is forcibly opened when the pressure of the hydraulic oil guided from the second passage 3b through the pilot pressure passage 6a increases.

[0021] The pilot check valve 4b allows the flow of hydraulic oil from the tank T to the second passage 3b, and prevents the flow of hydraulic oil from the second passage 3b to the tank T. In addition, the pilot check valve 4b is forcibly opened when the pressure of the hydraulic oil guided from the first passage 3a through the pilot pressure passage 6b increases.

[0022] The operation of the hydraulic circuit S thus configured will be described.

[0023] When the pump 1 rotates so as to discharge hydraulic oil from the port 1a (hereinafter, the rotation of the pump 1 so as to discharge hydraulic oil from the port 1a is referred to as "forward rotation"), the hydraulic oil discharged from the port 1a is supplied to the rod side chamber 2d of the cylinder 2 through the first passage 3a. At this time, the hydraulic oil in the anti-rod side chamber 2e is sucked into the pump 1 through the second passage 3b and the port 1b.

[0024] The hydraulic oil in the first passage 3a is also supplied to the pilot check valve 4b through the pilot pressure passage 6b. The pilot check valve 4b opens when the hydraulic oil in the first passage 3a is supplied to it.

[0025] The volume per unit length of the anti-rod side chamber 2e is larger than the volume per unit length of the rod side chamber 2d by the volume of the piston rod 2c. Therefore, the amount of hydraulic oil discharged from the anti-rod side chamber 2e is greater than the amount of hydraulic oil supplied to the rod side chamber 2d. In the hydraulic circuit S, the hydraulic oil discharged from the anti-rod side chamber 2e is sucked from the port 1b of the pump 1, but the amount of hydraulic oil discharged from the anti-rod side chamber 2e exceeds the amount of hydraulic oil supplied to the rod side chamber 2d. Therefore, when the pump 1 discharges hydraulic oil from the port 1a, the surplus hydraulic oil in the second passage 3b on the suction side (hydraulic oil not sucked into the pump 1) is discharged to the tank T through the pilot check valve 4b. Note that when the pump 1 is rotating forward, if the pressure of the hydraulic oil in the second passage 3b becomes negative (lower than the pressure of the tank T), hydraulic oil is supplied from the tank T to the second passage 3b through the pilot check valve 4b.

[0026] In this way, when the pump 1 rotates forward, hydraulic oil is supplied into the rod side chamber 2d and hydraulic oil is discharged from the anti-rod side chamber 2e, thereby driving the cylinder 2 to contract the piston rod 2c.

[0027] In contrast, when the pump 1 rotates so as to discharge hydraulic oil from port 1b (hereinafter, the rotation of the pump 1 so as to discharge hydraulic oil from port 1b is referred to as "reverse rotation"), the hydraulic oil discharged from port 1b is supplied to the anti-rod side chamber 2e of the cylinder 2 through the second passage 3b. At this time, the hydraulic oil in the rod side chamber 2d is sucked into the pump 1 through the first passage 3a and port 1a.

[0028] The hydraulic oil in the second passage 3b is supplied to the pilot check valve 4a through a pilot pressure passage 6a. The pilot check valve 4a opens when the hydraulic oil in the second passage 3b is supplied.

[0029] As described above, the volume per unit length of the anti-rod side chamber 2e is larger than the volume per unit length of the rod side chamber 2d by the volume of the piston rod 2c. Therefore, the amount of hydraulic oil supplied to the anti-rod side chamber 2e is greater than the amount of hydraulic oil discharged from the rod side chamber 2d. In the hydraulic circuit S, the hydraulic oil discharged from the rod side chamber 2d is sucked from the port 1a of the pump 1, but the amount of hydraulic oil discharged from the rod side chamber 2d is less than the amount of hydraulic oil supplied to the anti-rod side chamber 2e. Therefore, when the pump 1 discharges hydraulic oil from the port 1b, the hydraulic oil that is insufficient in the first passage 3a on the suction side is supplied from the tank T through the pilot check valve 4b. Note that when the pump 1 is rotating in the reverse direction, if the pressure of the hydraulic oil in the first passage 3a becomes negative (lower than the pressure of the tank T), the hydraulic oil is supplied from the tank T to the first passage 3a through the pilot check valve 4a.

[0030] In this way, when the pump 1 rotates in reverse, hydraulic oil is supplied into the anti-rod side chamber 2e and hydraulic oil is discharged from the rod side chamber 2d, thereby driving the cylinder 2 to protrude the piston rod 2c.

[0031] Furthermore, when the piston rod 2c is pulled in the extension direction of the cylinder 2 by an external force, the hydraulic oil in the rod side chamber 2d is pushed out by the piston 2b into the first passage 3a, and the pressure of the hydraulic oil in the first passage 3a increases. When the pressure of the hydraulic oil in the first passage 3a increases to a predetermined value P1, the relief valve 5a opens and the hydraulic oil in the first passage 3a is discharged to the tank T. This makes it possible to prevent the pressure of the hydraulic oil in the first passage 3a from becoming high.

[0032] Furthermore, when the piston 2b moves in the extension direction of the cylinder 2, the volume of the anti-rod side chamber 2e expands. When the pump 1 is stopped, no hydraulic oil is supplied from the pump 1 to the anti-rod side chamber 2e. In this case, hydraulic oil is supplied from the tank T to the second passage 3b and the anti-rod side chamber 2e through the pilot check valve 4b, so that the pressure of these hydraulic oils can be prevented from becoming negative.

[0033] In contrast, when the piston rod 2c is pushed in the contraction direction of the cylinder 2 by an external force, the hydraulic oil in the anti-rod side chamber 2e is pushed out by the piston 2b into the second passage 3b, and the pressure of the hydraulic oil in the second passage 3b increases. When the pressure of the hydraulic oil in the second passage 3b increases to a predetermined value P1, the relief valve 5b opens and the hydraulic oil in the first passage 3a is discharged to the tank T. This makes it possible to prevent the pressure of the hydraulic oil in the second passage 3b from becoming high.

[0034] Furthermore, when the piston 2b moves in the contraction direction of the cylinder 2, the volume of the rod side chamber 2d expands. When the pump 1 is stopped, no hydraulic oil is supplied from the pump 1 to the rod side chamber 2d. In this case, hydraulic oil is supplied from the tank T to the first passage 3a and the rod side chamber 2d through the pilot check valve 4a, so that the pressure of the hydraulic oil can be prevented from becoming negative.

[0035] Next, a specific configuration of the valve device 100 will be described with reference to Figures 2 and 3. Figure 2 is a cross-sectional view of the valve device 100, and Figure 3 is an enlarged view of the vicinity of the pilot check valve 4a and the relief valve 5a in Figure 2.

[0036] 2, the valve device 100 includes a housing 10, pilot check valves 4a, 4b, and relief valves 5a, 5b. The housing 10 is provided with a pump port 11a communicating with the port 1a of the pump 1, a cylinder port 12a as a second port communicating with the rod side chamber 2d of the cylinder 2, a pump port 11b communicating with the port 1b of the pump 1, a cylinder port 12b communicating with the anti-rod side chamber 2e of the cylinder 2, and a tank port 13 as a first port communicating with the tank T.

[0037] The pump port 11a and the cylinder port 12a are connected by a passage 15a. The passage 15a constitutes a part of the first passage 3a. The pump port 11b and the cylinder port 12b are connected by a passage 15b. The passage 15b constitutes a part of the second passage 3b.

[0038] The tank port 13 is provided between and next to the pump port 11a and the pump port 11b.

[0039] The housing 10 is further provided with an accommodating hole 14 for accommodating the pilot check valves 4a, 4b and the relief valves 5a, 5b. In this embodiment, the accommodating hole 14 is formed to penetrate the housing 10 and intersect with the passages 15a and 15b.

[0040] Next, the specific structures of the pilot check valves 4a, 4b and the relief valves 5a, 5b will be described. Since the pilot check valve 4a and the relief valve 5a and the pilot check valve 4b and the relief valve 5b have the same structure, only the structures of the pilot check valve 4a and the relief valve 5a will be described below, and the explanation of the pilot check valve 4b and the relief valve 5b will be omitted.

[0041] As shown in FIG. 3, the pilot check valve 4a includes a valve body 41 slidably received in the receiving hole 14, a spring 42 as a biasing member that biases the valve body 41 in the valve closing direction, and a spring receiver 45.

[0042] The valve body 41 has a cylindrical main body portion 41a, a large diameter portion 41b that is continuous with the main body portion 41a and has a larger diameter than the main body portion 41a, a small diameter portion 41c that is provided on the opposite side of the large diameter portion 41b with respect to the main body portion 41a and has a smaller diameter than the main body portion 41a, a seat portion 41d that is provided on the tip side of the small diameter portion 41c and seats on and releases from a valve seat portion 14a formed in the accommodating hole 14 of the housing 10, a plurality of communication holes 41e that are provided at the boundary between the main body portion 41a and the small diameter portion 41c and communicate between the outside and the inside of the valve body 41, an O-ring 43 that is attached to the main body portion 41a and serves as a first seal member that seals between the accommodating hole 14 and the main body portion 41a, and an O-ring 44 that is attached to the large diameter portion 41b and serves as a second seal member that seals between the accommodating hole 14 and the large diameter portion 41b.

[0043] The spring 42 is formed of a coil spring, and is held in a compressed state between a spring receiver 45 and a cover member 46 that closes the receiving hole 14 .

[0044] The valve device 100 further includes a pilot pressure chamber 60 to which the pressure of the second passage 3b is guided through the pilot pressure passage 6a. The pilot pressure chamber 60 is formed between the inner circumferential surface of the accommodating hole 14 and the outer circumferential surface of the valve body 41, and between the O-ring 43 and the O-ring 44. In other words, the pilot pressure chamber 60 is a region defined by the inner circumferential surface of the accommodating hole 14, the outer circumferential surface of the valve body 41, the O-ring 43, and the O-ring 44.

[0045] As shown in FIG. 3, the relief valve 5a includes a valve body 51, a spring 52 serving as a biasing member that biases the valve body 51 in a valve closing direction, and a valve seat member 53.

[0046] The spring 52 is formed of a coil spring, and is held in a compressed state between the valve body 51 and a spring receiving portion 41f formed inside the valve body 41.

[0047] The valve seat member 53 is fixed in the valve body 41 by screwing or the like. The valve seat member 53 is provided with a seat portion 53a on which the valve body 51 seats and leaves, and a plurality of communication holes 53b that communicate between the outside and the inside of the valve seat member 53. As a result, the inside of the valve seat member 53 (internal passage 53c) is constantly in communication with the passage 15a through the communication holes 53b and the communication holes 41e.

[0048] Furthermore, the spring receiver 45 is fixed inside the valve seat member 53. As a result, the biasing force of the spring 42 acts on the valve body 41 via the spring receiver 45 and the valve seat member 53, and the seat portion 41d of the valve body 41 is pressed so as to seat on the valve seat portion 14a.

[0049] Next, the operations of the pilot check valve 4a and the relief valve 5a will be specifically described with reference to FIGS.

[0050] First, the operation of the pilot check valve 4a will be described.

[0051] The pilot check valve 4a has a seat portion 41d of the valve body 41 seated on the valve seat portion 14a of the housing 10 by the spring 42. This blocks communication between the first passage 3a (passage 15a) and the tank T. When the pressure of the tank T exceeds the pressure of the hydraulic oil in the first passage 3a (passage 15a), in other words, when the pressure of the hydraulic oil in the first passage 3a (passage 15a) becomes less than the tank pressure (negative pressure), the valve body 41 of the pilot check valve 4a moves against the biasing force of the spring 42 and opens.

[0052] As described above, the valve device 100 includes the pilot pressure chamber 60. The pressure of the hydraulic oil introduced into the pilot pressure chamber 60 acts on the large diameter portion 41b of the valve body 41. The pressure of the hydraulic oil acting on the large diameter portion 41b urges the valve body 41 in the valve opening direction.

[0053] As the pressure in the second passage 3b increases, the pressure in the pilot pressure chamber 60 increases, and when the biasing force in the valve opening direction due to the pressure acting on the large diameter portion 41b of the valve element 41 exceeds the biasing force in the valve closing direction due to the spring 42, the valve element 41 moves against the biasing force of the spring 42 and opens. This allows the first passage 3a (passage 15a) to communicate with the tank T, and allows the fluid to flow from the first passage 3a (passage 15a) to the tank T.

[0054] Next, the operation of the relief valve 5a will be described.

[0055] As described above, the inside of the valve seat member 53 (the internal passage 53c) is always in communication with the first passage 3a (passage 15a) through the communication hole 53b and the communication hole 41e. When the pressure of the hydraulic oil in the first passage 3a (passage 15a) increases, the urging force that urges the valve body 51 of the relief valve 5a in the valve opening direction increases through the communication hole 53b, the communication hole 41e, and the internal passage 53c. Then, when the pressure of the hydraulic oil in the first passage 3a (passage 15a) becomes equal to or higher than the predetermined value P1, the valve body 51 moves against the urging force of the spring 52, and the valve body 51 opens. As a result, the hydraulic oil in the first passage 3a (passage 15a) is discharged to the tank T through the communication hole 53b, the communication hole 41e, the internal passage 53c, and the tank port 13.

[0056] In this manner, in the valve device 100, the pilot pressure chamber 60 is provided between the inner circumferential surface of the accommodation hole 14 of the housing 10 and the outer circumferential surface of the valve body 41 of the pilot check valves 4a, 4b. This eliminates the need for parts such as pistons for forcibly opening the valve bodies 41 of the pilot check valves 4a, 4b, thereby reducing the number of parts.

[0057] Furthermore, in the valve device 100, the relief valves 5a and 5b are provided inside the valve bodies 41 of the pilot check valves 4a and 4b, respectively, so that the device can be prevented from becoming large in size.

[0058] In the valve device 100, the pilot pressure chamber 60 is formed by partitioning the inner peripheral surface of the accommodation hole 14 and the outer peripheral surface of the valve body 41 with the O-rings 43 and 44. In this manner, in the valve device 100, the pilot pressure chamber 60 is formed by adding the O-rings 43 and 44, so that an increase in the number of parts can be suppressed. Also, leakage of the fluid guided to the pilot pressure chamber 60 can be suppressed.

[0059] In the above embodiment, the valve device 100 is described as including the pilot check valves 4a, 4b and the relief valves 5a, 5b, but may be configured to include only one of these.

[0060] Furthermore, if the sealing performance between the inner peripheral surface of the receiving hole 14 and the outer peripheral surface of the valve body 41 can be ensured, the O-rings 43 and 44 do not need to be provided.

[0061] Furthermore, in the above embodiment, the valve device 100 is applied to the hydraulic circuit S that is configured as a closed circuit, but the valve device 100 may be applied to any type of hydraulic circuit.

[0062] The shapes of the above-mentioned components are merely examples of the embodiment, and may be modified as appropriate without departing from the technical spirit of the present invention.

[0063] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0064] The valve device 100 includes a housing 10 having a first port (tank port 13) and a second port (cylinder ports 12a, 12b), an accommodating hole 14 formed in the housing 10, and pilot check valves 4a, 4b accommodated in the accommodating hole 14 to allow fluid to flow from the first port (tank port 13) to the second port (cylinder ports 12a, 12b) and to block fluid flow from the second port (cylinder ports 12a, 12b) to the first port (tank port 13). A valve element 41 of the pilot check valves 4a, 4b has a cylindrical main body portion 41a and a large diameter portion 41b having a diameter larger than that of the main body portion 41a. A fluid for opening the valve element 41 of the pilot check valves 4a, 4b is guided to a pilot pressure chamber 60 defined by the main body portion 41a, the large diameter portion 41b, and the inner circumferential surface of the accommodating hole 14.

[0065] In this configuration, a pilot pressure chamber 60 is provided between the inner peripheral surface of the accommodation hole 14 of the housing 10 and the outer peripheral surface of the valve body 41 of the pilot check valves 4a, 4b. This eliminates the need for parts such as pistons for forcibly opening the valve bodies 41 of the pilot check valves 4a, 4b, allowing the number of parts to be reduced. In addition, since no space is required for providing pistons, the valve device 100 can be made more compact.

[0066] The valve device 100 has a first sealing member (O-ring 43) attached to the main body portion 41a and sealing between the accommodating hole 14 and the main body portion 41a, and a second sealing member (O-ring 44) attached to the large diameter portion 41b and sealing between the accommodating hole 14 and the large diameter portion 41b, and the pilot pressure chamber 60 is formed between the first sealing member (O-ring 43) and the second sealing member (O-ring 44).

[0067] With this configuration, leakage of the fluid guided to the pilot pressure chamber 60 can be suppressed.

[0068] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0069] 100 valve device, 1 pump, 2 cylinder, 2d rod side chamber, 2e anti-rod side chamber, 3a first passage, 3b second passage, 4a pilot check valve, 4b pilot check valve, 5a relief valve, 5b relief valve, 6a pilot pressure passage, 6b pilot pressure passage, 10 housing, 11a pump port, 11b Pump port, 12a cylinder port (second port), 12b cylinder port (second port), 13 tank port (first port), 14 accommodation hole, 41 valve body, 41a main body, 41b large diameter portion, 43 O-ring (first seal member), 44 O-ring (second seal member), 51 valve body, 60 pilot pressure chamber, S hydraulic circuit, T tank

Claims

1. a housing having a first port and a second port; A receiving hole formed in the housing; a pilot check valve received in the receiving hole for allowing a fluid to flow from the first port to the second port and for preventing a fluid to flow from the second port to the first port, The valve body of the pilot check valve is A cylindrical main body portion; a large diameter portion having a diameter larger than that of the main body portion; a pilot pressure chamber defined by the main body portion, the large diameter portion, and the inner circumferential surface of the receiving hole, through which a fluid for opening the valve element of the pilot check valve is guided.

2. 2. The valve device according to claim 1, a first seal member attached to the main body portion and sealing between the receiving hole and the main body portion; a second seal member attached to the large diameter portion and sealing between the accommodating hole and the large diameter portion, The valve device, wherein the pilot pressure chamber is formed between the first seal member and the second seal member.

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