WO2015162099A1

WO2015162099A1 - Slow return check valve

Info

Publication number: WO2015162099A1
Application number: PCT/EP2015/058530
Authority: WO
Inventors: Yuya Kanenawa; Genta MINE
Original assignee: Caterpillar SARL
Current assignee: Caterpillar SARL
Priority date: 2014-04-22
Filing date: 2015-04-20
Publication date: 2015-10-29
Anticipated expiration: 2016-10-22
Also published as: CN106170651A; JP2015206426A

Abstract

To provide a slow return check valve that is easy to adjust amount of oil flow volume and prevent from clogging contamination as well. SOLUTION: This invention provides a slow return check valve (1) comprising an outer valve body (2) having the first and second port (6,7), an inner valve body (3) fitted inwardly to a storage chamber (8) formed at the outer valve body (2), a valve body (4) fitted inwardly of and movable with respect to the inner valve body (3), an annular clearance (9) being provided as throttle and having an axial lengthwise direction between inner surface of the storage chamber (8) and the outer surface of the inner valve body (3), and further a communication passage (10-13) that connects the annular clearance (9) and the first and second port (6,7) being mounted so that oil flow through a valve passage (17) is prevented and amount of oil flow is regulated when the oil flows from the second port (7) to the first port (6).

Description

DESCRIPTION

SLOW RETURN CHECK VALVE

TECHNICAL FIELD

[0001]

The present invention relates to a technical field of a slow return,check valve that allows fluid to freely flow in one direction and regulates the flow rate of the fluid by a throttle in a reverse direction .

BACKGROUND ART

[0002]

In general, various valves for controlling the flow direction, flow rate, and pressure of an operating oil are provided in a hydraulic working machine having a hydraulic actuator, such as a construction machine. An example of such valves is a slow return check valve (one-way throttle valve) . The slow return check valve allows fluid to freely flow in one direction and regulates the flow rate of the fluid by a throttle in a reverse direction, for example, is used for delaying a decrease in pressure on a load side when returning oil from the load side to an oil tank.

Conventionally, an electromagnetic slow return check valve and a slow return check valve (the slow return valve illustrated in Fig. 15 of Patent Literature 1, for example) having an orifice formed in a valve element are known as the slow return check valve. An electromagnetic slow return check valve can control the flow rate with the aid of a throttle but has a problem in that such valve is expensive. On the other hand, a slow return check valve having an orifice formed in a valve element controls the flow rate by controlling the orifice diameter. In this case, when it is desired to set the delay time for delaying the decrease in the pressure on the load side to be long when returning oil from the load side to .the oil tank, for example, it is necessary to decrease the orifice diameter to reduce the flow rate of oil passing through the orifice. However, the smaller the orifice diameter, the more contaminations are likely to clog. The contaminations may block the orifice, and there is a limit on decreasing the orifice diameter. Thus, it is difficult to set the delay time to be long.

Thus, a technique is proposed in which a notch groove is formed by being notched in a cylindrical projection that forms a valve element of a slow return check valve, and the notch groove applies resistance to the flow of fluid to regulate the flow rate when the cylindrical projection sits on a valve seat, whereas the notch groove is open to a valve element storage portion to remove contaminations adhering to the notch groove with the aid of pressurized oil flowing into the valve element storage portion when the cylindrical projection is separated from the valve seat (for example, see Patent Literature 2) .

[0003]

Patent Literature 1: Japanese Patent Application Publication No. 2007-92807

Patent Literature 2 : Japanese Patent Application Publication No. 2007-255445

DISCLOSURE OF THE INVENTION

[0004]

.. However, the notch groove formed by being notched as in Patent Literature 2 has a problem in that contaminations are likely to clog even when the notch groove is open to the valve element storage portion when the cylindrical projection is separated from the valve seat. Moreover, according to this technique, the flow rate is regulated in accordance with the cross-sectional area of the notch groove. Thus, when it is desired to set the delay time for delaying the decrease in the pressure on the load side when returning oil from the load side to the oil tank, the cross-sectional area of the notch groove is set to be small so that the flow rate of oil passing through the notch groove decreases. However, the smaller the cross-sectional area of the notch groove, the higher the possibility of contaminations clogging the notch groove, which is to be solved by the present invention.

[0005]

With the foregoing in view, the present invention has been made to solve such problems. An invention according to claim 1 is a slow return check valve including: an outer valve body having first and second ports; a circular hole-shape storage chamber formed in the outer valve body in a state of communicating with the first and second ports; a cylindrical inner valve body fitted into the storage chamber; and a valve element that is movably fitted into the inner valve body so as to open and close a valve passage that connects the first port and the second port, wherein an annular clearance serving as a throttle is provided between an inner circumferential surface of the storage chamber of the outer valve body and an outer circumferential surface of the inner valve body in a state of having a length in an axial direction, a communication passage that connects the annular clearance and the first and second ports is formed in the outer valve body or the inner valve body, the valve element moves in a valve passage opening direction due to pressure of oil flowing into the first port, whereby the oil freely flows from the first port to the second port via the valve passage, the valve element moves in a valve passage closing direction due to pressure of oil flowing into the second port, whereby the flow of oil from the second port to the first port via the valve passage is inhibited, and in a state where the flow of oil via the valve passage is inhibited, the oil of which the flow rate is regulated flows from the second port to the first port via the annular clearance and the communication passage.

[0006]

With the invention of claim 1, it is possible to provide excellent anti-contamination properties and to easily adjust the flow rate of fluid passing through an annular clearance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]

Fig. 1 is a cross-sectional view of a slow return check valve in a closed state of a valve passage.

Fig. 2 is a cross-sectional view of a slow return check valve in an open state of a valve passage.

Figs. 3A, 3B, and 3C are a front view, a side view, and a cross-sectional view of an inner valve body, respectively.

BEST MODE FOR CARRYING OUT THE INVENTION

[0008]

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 is a slow return check valve. The slow return check valve 1 is used, for example, for delaying a decrease in the pressure on a load side of a hydraulic cylinder or the like when returning oil from the load side to an oil tank to thereby slow down an operating speed of a load. The slow return check valve 1 includes members including an outer valve body 2, an inner valve body 3, a valve element 4, a spring 5, and the like which will be described later.

[0009]

The outer valve body 2 that forms the slow return check valve

1 is formed by integrally assembling a first outer valve body 2a having a first port 6 and a second outer valve body 2b having a second port 7 by screwing 2c . In the following description, an outer valve body in which the first and second outer valve bodies 2a and 2b are assembled integrally is described as the outer valve body

2 without distinguishing the first outer valve body 2a from the second outer valve body 2b. However, in the present embodiment, the first port 6 is connected to an oil pump or an oil tank via a switching valve, and the second port 7 is connected to a hydraulic actuator (load) (the oil pump, oil tank and hydraulic actuator are not illustrated in the drawings) . Further, a circular hole-shaped storage chamber 8 having a larger diameter than the first and second ports 6 and 7 and communicating with the first and second ports 6 and 7 is formed in the outer valve body 2. The storage chamber 8 is disposed so as to be positioned between the first port 6 and the second port 7 on the same axis as the first and second ports 6 and 7. A half portion of the storage chamber 8 close to the second port 7 has a diameter slightly larger than the diameter of the other half portion close to the first port 6.

[0010]

The cylindrical inner valve body 3 is fitted into the storage chamber 8. The inner valve body 3 has an inner cylinder portion which communicates with the first and second ports 6 and 7, and a large-diameter portion 3a having a slightly larger diameter than the other outer circumferential portions and having a length of L in an axial direction is formed in a portion of the outer circumferential portion of the inner valve body 3 close to the first port 6. A very small annular clearance 9 serving as a throttle is formed between an outer circumferential surface of the large-diameter portion 3a and an inner circumferential surface of the storage chamber 8 (in Figs. 1 and 2, a width S in a radial direction of the annular clearance 9 is depicted to be larger than the actual size for better understanding of the structure) . Moreover, a first annular communication passage 10 that communicates with the annular clearance 9 is formed between the inner circumferential surface of the storage chamber 8 and the outer circumferential surface of the inner valve body 3 located closer to the first port 6 than the large-diameter portion 3a. Further, a second annular communication passage 11 that communicates with the annular clearance 9 is formed between the inner circumferential surface of the storage chamber 8 and the outer circumferential surface of the inner valve body 3 located closer to the second port

7 than the large-diameter portion 3a.

[0011]

Further, a first port-side end surface 3b of the inner valve body 3 faces a first port-side end surface 8a of the storage chamber

8. A plurality of groove-shaped first communication passages 12 (in the present embodiment, four communication passages are arranged at intervals of 90° in the circumferential direction) which extends from the inner circumference side of the inner valve body 3 to reach the outer circumference side is formed in a radial form in the first port-side end surface 3b of the inner valve body 3. The first port 6 communicates with the first annular communication passage 10 through the first communication passages 12. Moreover, a second port-side end surface 3c of the inner valve body 3 faces a second port-side end surface 8b of the storage chamber 8. A gap which serves as a second communication passage 13 when the valve element 4 closes the valve , passage 17 as will be described later is formed between the second port-side end surface 3c of the inner valve body 3 and the second port-side end surface 8b of the storage chamber 8. The second port 7 communicates with the second annular communication passage 11 through the second communication passage 13 (the gap between the second port-side end surface 3c of the inner valve body 3 and the second port-side end surface 8b of the storage chamber 8) . As a result, the first port 6 and the second port 7 communicate with each other through the first communication passage 12, the first annular communication passage 10, the annular clearance 9, the second annular communication passage 11, and the second communication passage 13. The first and second annular communication passages 10 and 11 and the first and second communication passages 12 and 13 form a communication passage of the present invention. These communication passages 10 to 13 have such a passage area that the passages do not act as a throttle when operating oil passes therethrough.

[0012]

Here, the length in the axial direction of the inner valve body 3 is set to be slightly smaller than the length in the axial direction of the storage chamber 8. In a state where the valve element 4 sits on a valve seat 14 to close the valve passage 17 as will be described later, the inner valve body 3 is pressed toward the first port-side end surface 8a of the storage chamber 8 by the valve element 4. Due to this, the first port-side end surface 3b of the inner valve body 3 comes into contact with the first port-side end surface 8a of the storage chamber 8, and a gap serving as the second communication passage 13 is formed between the second port-side end surface 3c of the inner valve body 3 and the second port-side end surface 8b of the storage chamber 8.

[0013]

Further, the valve seat 14 that projects in an inward flange form toward the inner cylinder portion is formed in an end of the inner circumferential portion of the inner valve body 3 close to the first port 6. A seat portion 4a (described Later) of the valve element 4 that is fitted to the inner cylinder portion of the inner valve body 3 so as to be movable in the axial direction is separably attached to the valve seat 14.

[0014]

The valve element 4 includes a seat portion 4a that is separably attached to the valve seat 14 and a cylindrical portion 4b which is provided closer to the second port 7 than the second seat portion 4a and of which the outer circumferential portion makes sliding contact with the inner circumferential surface of the inner valve body 3 so as to be movable in the axial direction. An inner passage 15 that communicates with the second port 7 is formed in the inner cylinder portion of the cylindrical portion 4b. Further, a plurality of communication holes 16 (in the present embodiment, four communication holes) which extends from the inner passage 15 to the outer circumference side of the valve element 4 is formed in a radial form in a portion of the valve element 4 disposed between the seat portion 4a and the cylindrical portion 4b, whereby the inner cylinder portion of the inner valve body 3 communicates with the second port 7 by the communication holes 16 and the inner passage 15. The seat portion 4a of the valve element 4 sits on the valve seat 14 when the valve element 4 moves toward the first port 6, and the seat portion 4a is separated from the valve seat 14 when the valve element 4 moves toward the second port 7. In a state where the seat portion 4a is separated from the valve seat 14, the first port 6 communicates with the inner cylinder portion of the inner valve body 3. As a result, the valve passage 17 that connects the first port 6 and the second port 7 via the inner cylinder portion of the inner valve body 3, the communication hole 16, and the inner passage 15 is opened. On the other hand, in a state where the seat portion 4a sits on the valve seat 14, the first port 6 and the inner cylinder portion of the inner valve body 3 are blocked. As a result, the valve passage 17 that connects the first port 6 and the second port 7 is closed. Further, the valve element 4 is always pressed by the spring 5 in a direction (the valve passage closing direction) in which the seat portion 4a sits on the valve seat 14 (that is, the valve passage 17 is closed) .

[0015]

Here, reference numeral 18 is a second storage chamber which is formed in the outer valve body 2 in a state of being adjacent to the second port 7 side of the storage chamber 8 in order to secure the space for allowing the valve element 4 to move toward the second port 7 (in the direction in which the seat portion 4a is separated from the valve seat 14) . The second storage chamber 18 has approximately the same inner diameter as the inner diameter of the inner valve body 3. Moreover, reference numeral 19 is a third storage chamber which is formed in the outer valve body 2 in a state of being adjacent to the second port 7 side of the second storage chamber 18 so that one end of the spring 5 is stored. The spring 5 is disposed such that one end thereof is locked at a second port-side end surface 19a of the third storage chamber 19 and the other end is locked at a step 15a formed in an intermediate portion of the inner passage 15 of the valve element 4.

[0016]

When pressurized oil is supplied from a hydraulic pump to a hydraulic actuator via the slow return check valve 1, the oil flows from the first port 6 to the second port 7. The flow of oil from the first port 6 to the second port 7 is such that the valve element 4 is moved in a direction away from the valve seat 14 while resisting against the biasing force of the spring 5 due to the pressure of oil flowing into the first port 6 to open the valve passage 17, whereby the oil can freely from the first port 6 to the second port 7 via the valve passage 17.

[0017]

On the other hand, when oil is supplied from the hydraulic actuator to the oil tank via the slow return check valve 1, the oil flows from the second port 7 to the first port 6. The flow of oil from the second port 7 to the first port 6 is such that the valve element 4 is moved in a direction of sitting on the valve seat 14 due to the pressure of the oil flowing into the second port 7 to close the valve passage 17, whereby the flow from the second port 7 to the first port 6 via the valve passage 17 is inhibited. In a state where the flow via the valve passage 17 is inhibited, the oil flows from the second port 7 to the first port 6 via the second communication passage 13, the second annular communication passage 11, the annular clearance 9, the first annular communication passage 10, and the first communication passage 12. Moreover, the flow rate of the oil is regulated when the oil passes through the annular clearance 9 serving as a throttle. Thus, the flow from the second port 7 to the first port 6 is realized in a state where the flow rate is regulated. As a result, it is possible to delay the decrease in the pressure of the hydraulic actuator-side passage and to slow down the lowering speed when lowering heavy materials with the action of the hydraulic actuator, for example. Moreover, the flow rate of oil passing through the annular clearance 9 can be easily adjusted by changing the width S in the radial direction or the length L in the axial direction of the annular clearance 9 (that is, in the present embodiment, by changing the outer diameter or the length L in the axial direction of the large-diameter portion 3a of the inner valve body 3) .

[0018]

In the embodiment having the above-described configuration, the slow return check valve 1 includes : the outer valve body 2 having the first and second ports 6,and 7; the circular hole-shaped storage chamber 8 formed in the outer valve body 2 in a state of communicating with the first and second ports 6 and 7; the cylindrical inner valve body 3 fitted into the storage chamber 8; and the valve element 4 that is movably fitted into the inner valve body 3 so as to open and close the valve passage 17 that connects the first port 6 and the second port 7. The annular clearance 9 serving as a throttle is provided between the inner circumferential surface of the storage chamber 8 of the outer valve body 2 and the outer circumferential surface of the inner valve body 3 in a state of having a length in the axial direction. The communication passages 10 to 13 (the first and second annular communication passages 10 and 11 and the first and second communication passages 12 and 13) that connect the annular clearance 9 and the first and second ports 6 and 7 are provided in the outer valve body 2 or the inner valve body 3. The valve element 4 moves in a direction (valve passage opening direction) of opening the valve passage 17 due to the pressure of oil flowing into the first port 6 whereby the oil freely flows from the first port 6 to the second port 7 via the valve passage 17. The valve element 4 moves in a direction (valve passage closing direction) of closing the valve passage 17 due to the pressure of oil flowing into the second port 7 whereby the flow of oil from the second port 7 to the first port 6 via the valve passage 17 is inhibited. In a state where the flow of oil via the valve passage 17 is inhibited, oil of which the flow rate is regulated flows from the second port 7 to the first port 6 via the annular clearance 9 and the communication passages 10 to 13.

[0019]

Due to this, the flow rate of the oil flowing from the second port 7 to the first port 6 is regulated when the oil passes through the annular clearance 9 serving as a throttle. In this case, the annular clearance 9 is provided such that the power supply is rarely clogged due to contaminations and the annular clearance 9 has a length in the axial direction. Thus, it is possible to easily adjust the flow rate of oil passing through the annular clearance 9 by adjusting the length in the axial direction as well as the width in the radial direction. As a result, even when the width in the radial direction of the annular clearance 9 is not decreased too much by taking anti-contamination properties into consideration when it is desired to set the delay time for delaying the decrease in the pressure on the passage close to the second port 7 in the case of supplying oil from the second port 7 to the first port 6, it is possible to decrease the flow rate of oil passing through the annular clearance 9 by setting the length in the axial direction to be large. Thus, it is possible to provide excellent anti-contamination properties and to easily set the delay time for delaying the decrease in pressure to be long. Further, this slow return check valve has a simple structure that the annular clearance 9 serving as a throttle is provided between the inner circumferential surface of the storage chamber 8 of the outer valve body 2 and the outer circumferential surface of the inner valve body 3 fitted into the storage chamber 8 and has a small number of constituent components and thus can contribute to cost reduction.

INDUSTRIAL APPLICABILITY [0020]

The present invention can be used in a slow return check valve that allows fluid to freely flow in one direction and regulates the flow rate of the fluid by a throttle in a reverse direction.

EXPLANATION OF REFERENCE NUMERALS

[0021]

1: Slow return check valve

2: Outer valve body

3: Inner valve body

4 : Valve element

6: First port

7 : Second port

8 : Storage chamber

9: Annular clearance

10: First annular communication passage

11: Second annular communication passage

12: First communication passage

13: Second communication passage

14: Valve seat

17 : Valve passage

Claims

1. A slow return check valve comprising:

an outer valve body having first and second ports;

a circular hole-shape storage chamber formed in the outer valve body in a state of communicating with the first and second ports ;

a cylindrical inner valve body fitted into the storage chamber; and

a valve element that is movably fitted into the inner valve body so as to open and close a valve passage that connects the first port and the second port, wherein

an annular clearance serving as a throttle is provided between an inner circumferential surface of the storage chamber of the outer valve body and an outer circumferential surface of the inner valve body in a state of having a length in an axial direction,

a communication passage that connects the annular clearance and the first and second ports is formed in the outer valve body or the inner valve body,

the valve element moves in a valve passage opening direction due to pressure of oil flowing into the first port, whereby the oil freely flows from the first port to the second port via the valve passage,

the valve element moves in a valve passage closing direction due to pressure of oil flowing into the second port, whereby the flow of oil from the second port to the first port via the valve passage is inhibited, and

in a state where the flow of oil via the valve passage is inhibited, the oil of which the flow rate is regulated flows from the second port to the first port via the annular clearance and the communication passage.