WO2011113206A1

WO2011113206A1 - Bi-directional cartridge relief valve

Info

Publication number: WO2011113206A1
Application number: PCT/CN2010/071135
Authority: WO
Inventors: Gang Yu; Zhongming Ye; Fugang Li
Original assignee: WHITE (CHINA) DRIVE PRODUCTS CO Ltd
Current assignee: WHITE (CHINA) DRIVE PRODUCTS CO Ltd
Priority date: 2010-03-18
Filing date: 2010-03-18
Publication date: 2011-09-22
Anticipated expiration: 2012-09-18
Also published as: CN202484336U

Abstract

A bi-directional relief valve includes a cage (12) including a bore (32), a spool (14) located in the bore (32), and biasing means urging the spool towards a closed position. The cage further includes a first inlet/outlet port (50) and a second inlet/outlet port (52). Each port is connected with the bore. The bore includes a central section (38) having a first diameter and a reduced diameter section (42) having a second diameter, which is smaller than the first diameter. The spool is movable with respect to the cage within the bore. The spool includes a smaller diameter section (60) received in the reduced diameter section (42) of the bore and a larger diameter section (62) received within the central section (38) of the bore. The spool includes a passage (70) open to the first port (50) and a radial aperture (90) extending through the spool from the passage. The biasing means urges the spool towards the closed position where fluid flow is blocked through the radial aperture between the passage and the second port. When the biasing force of the biasing means is overcome, the spool moves toward an open position where the smaller diameter section of the spool moves toward the central section of the bore such that fluid flow is no longer blocked through the radial aperture between the passage and the second port.

Description

BI-DIRECTIONAL CARTRIDGE RELIEF VALVE

BACKGROUND

[0001] In hydraulic systems that include a hydraulic motor and a pump that supplies fluid to the hydraulic motor in two directions (forward rotation for the motor and backward rotation for the motor), it has been found to be desirable to provide pressure relief protection for the system when the system is operating in either direction. Previous hydraulic systems use two pressure relief valves, one arranged to provide pressure relief when the motor is operated in one direction and a second to provide relief when the motor is operated in an opposite direction.

[0002] Bi-directional pressure relief valves operate to relieve pressure in either direction between two fluid lines in a hydraulic system. A known bi-directional pressure relief valve includes a cage and a spool disposed in a bore of the cage. The cage includes a seat against which the spool acts to shut off flow between first and second ports when the spool is in the closed position. The spool includes a valve surface that seats against the seat to shut off the aforementioned flow.

[0003] Since in the known bi-directional pressure relief valve, the spool moves away from contacting the cage, i.e. the valve surface of the spool moves from the seat formed in the cage, alignment problems can arise and the spool may not properly seat against the valve seat. This can result in cross port leakage within the relief valve.

SUMMARY

[0004] An example of bi-directional relief valve that can overcome the aforementioned shortcomings includes a cage including a bore, a spool located in the bore, and biasing means urging the spool towards a closed position. The cage includes the bore, a first inlet/outlet port and second inlet/outlet port. Each port is connected with the bore. The bore includes a central section having a first diameter and a reduced diameter section having a second diameter, which is smaller than the first diameter. The spool is movable with respect to the cage within the bore. The spool includes a smaller diameter section received in the reduced diameter section of the bore and a larger diameter section received within the central section of the bore. The spool includes a passage open to the first port and a radial aperture extending through the spool from the passage. The biasing means urges the spool towards the closed position where fluid flow is blocked through the radial aperture between the passage and the second port. When the biasing force of the biasing means is overcome, the spool moves toward an open position where the smaller diameter section of the spool moves toward the central section of the bore such that fluid flow is no longer blocked through the radial aperture between the passage and the second port.

[0005] The bi-directional relief valve can also include a ring connected with the cage. The ring extends into the bore. The spool contacts the ring when the spool is in the closed position to retain the spool in the bore.

[0006] The aforementioned biasing means can be a spring. Where the biasing means is a spring, the spring contacts the spool. The valve can also include a spring retainer. The spring retainer includes a counterbore that receives the spring. The counterbore can have an axial length that is greater than 2/3 the length of the spring measured in an axial direction.

[0007] The biasing means can also be a valve arrangement configured to permit fluid pressure about equal to a fluid pressure of whichever port is at a lower pressure to act against the spool to urge the spool toward a closed position. The valve arrangement can include first and second one-way check valves.

[0008] When the smaller diameter section of the spool moves toward the central section of the bore such that fluid flow is no longer blocked through the radial aperture between the passage and the second port, a portion of the smaller diameter section of the spool can still remain in the reduced diameter section of the bore. The portion of the smaller diameter section of the spool still remaining in the reduced diameter section can be disposed between the radial aperture and the first port in an axial direction.

[0009] Another example of a bi-directional relief valve includes a cage including a bore, a spool located in the bore, and biasing means. The cage includes the bore, a first inlet/outlet port and a second inlet/outlet port. Each port is connected with the bore. The spool is movable with respect to the cage within the bore between a first operating position and a second operating position. The spool includes a passage. The passage is open to the first port in both the first operating position and the second operating position. The passage is blocked with respect to the second port when in the first operating position and is open to the second port when in the second operating position. The biasing means urges the spool towards the first operating position.

[0010] At least a portion of the spool can contact the cage when in the first operating position and when in the second operating position. The spool can include a radial aperture connected with the passage. The radial aperture can be blocked with respect to the second port when in the first operating position and can be open to the second port when in the second operating position. The portion of the spool contacting the cage when in the first operating position can be disposed between the radial aperture and the first port in an axial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIGURE 1 is a cross-sectional view of a bi-directional relief valve.

[0012] FIGURE 2 is a perspective view of the bi-directional relief valve shown in FIGURE 1 .

DETAILED DESCRIPTION

[0013] With reference to FIGURE 1 , a bi-directional relief valve 10 includes a cage 12 and a spool 14. The bi-directional relief valve 10 also includes biasing means, which will be described in more detail below, urging the spool 14 towards a closed position (first operating position), which will also be described in more detail below. The bi-directional relief valve 10 provides bi-directional pressure relief to a hydraulic system (not shown) when the hydraulic system is operated in either direction, i.e. fluid is flowing in either direction.

[0014] In the depicted embodiment, the cage 12 includes a head 1 6 and a generally cylindrical shank 18, which can take other configurations, extending from the head in an axial direction. As more clearly seen in FIGU RE 2, the head 1 6 is generally a hexagonal configuration, but the head can take other configurations. The cage 12 also includes an externally threaded section 22 on the shank 18 which facilitates threaded insertion of the bi-directional valve 10 into a manifold or other hydraulic device housing. A first external seal 24 surrounds the shank 18 near the head 1 6 of the cage 12. A second external seal assembly 26 surrounds the shank 18 of the cage 12 adjacent a distal end 28 of the cage 12. The external seals 24 and 26 seal the cage 12 with respect to the manifold or housing that receives the cage 12.

[0015] In the depicted embodiment, the cage 12 includes a bore 32 that extends axially through the cage 12 from the distal (first) end 28 to a second end 34, which is adjacent the head 1 6. The bore 32, which in the illustrated embodiment is centrally located in the cage 12, defines an internal wall 36 that cooperates with the spool 14 in a manner that will described in more detail below.

[0016] The bore 32 includes a central section 38, a reduced diameter end section 42, and an enlarged diameter end section 44. The bore 36 can be manufactured by boring first from the second end 34 of the cage 12 toward the first end 28 to form a bore having the diameter of the reduced diameter end section 32, next forming the central section 38, and finally forming the enlarged diameter section 44. A first chamfered transition shoulder 46 is provided between the central section 38 and the reduced diameter section 36.

[0017] The cage 12 also includes a first inlet/outlet port 50 and a second inlet/outlet port 52. Each port 50, 52 is connected with the bore 32 so that fluid entering each port 50, 52 also enters the bore 32. In the depicted embodiment, the first port 50 is a generally circular axial opening formed in the distal end 28 of the cage 12. The second port 52 is a radial opening (a plurality of radial openings are provided in the illustrated embodiment) extending through the cage 12. The first port 50 opens to the reduced diameter end section 36 of the bore 32. The second port 52 opens to the central section 38 of the bore 32. In the depicted embodiment, and as more clearly seen in FIGURE 2, the second port 52 can be a plurality of radial openings formed around the circumference of the cage 12. The cage 12 can also include a second plurality of radial openings 54 that are axially offset from the second port 52. The second radial openings 54 also connect with the central section 38 of the bore 32. The radial openings forming the second port 52 and the second plurality of radial openings 54 are located in an annular channel 56 (FIGURE 2) formed in the exterior of the case 12. The annular channel 56 is disposed between the first external seal 24 and the second external seal assembly 26 so as to be isolated from ambient and the first port 50 when the valve 10 is threaded into a housing (not shown).

[0018] The spool 14 is movable with respect to the cage 12 within the bore 32. The spool 14 is movable with respect to the cage 12 within the bore between a first operating position, e.g. a closed position, and a second operating position, e.g. an open position. The spool 14 includes a smaller diameter section 60 that is received in the reduced diameter end section 36 of the bore 32. The smaller diameter section 60 of the spool 14 is only slightly smaller than the reduced diameter end section 36 of the bore 32, which allows the spool to block flow between the first port 50 and the second port 52 in a manner that will be described in more detail below. The spool 14 also includes a larger (with respect to the smaller diameter section) diameter section 62 received within the central section 38 of the bore 32 and within the enlarged diameter end section 44 of the bore 32. The larger diameter section 62 of the spool 14 is only slightly smaller than the central section 38 of the bore 32, which allows the spool to move in the axial direction within the cage 12. A shoulder 64, which in the depicted embodiment is curved, provides the transition between the smaller diameter section 60 and the larger diameter section 62. The curved shoulder 64 is axially aligned with the radial openings forming the second port 52 when the spool 14 is in the closed position; the relevance of which will be described in more detail below.

[0019] The spool 14 also includes an axial passage 70 that is coaxial with the bore 32. The axial passage 70 is open to the first port 50 in both the first operating position (closed position) and the second operating position (open position). The axial passage 70 is blocked with respect to the second port 52 when in the first operating position and is open to the second port when in the second operating position. The axial passage 70 includes a first check valve bore 72 and a first check valve seat 74. The axial passage 70 continues through the spool 14 from one axial end to the other axial end of the spool and defines a spring counterbore 76 at the end furthest from the first port 50.

[0020] A radial passage 78 connects with the axial passage 70 and includes a check ball seat 82 formed therein. The radial passage 78 opens to an annular channel 84 formed around the circumference of the spool 14. The annular channel 84 is axially aligned with the second plurality of radial openings 54 that extend through the cage 12 when the spool 14 is in the closed position and when the spool is in an open position.

[0021] The valve spool 14 also includes radial apertures 90 that extend through the spool 14 and connect to the central passage 70. When the spool 14 is in the closed position (as shown in FIGURE 1 ) fluid flow is blocked through the radial apertures 90 between the passage 70 and the second port 52. When the spool 14 moves into the open position (to the right per the orientation shown in FIGURE 1 ), the smaller diameter section 60 of the spool 14 moves toward the central section 38 of the bore 32 such that fluid flow is no longer blocked through the radial apertures 90 between the passage 70 and the second port 52. Accordingly, when in the open position (the second operating position) fluid can flow through the bi-directional relief valve in either direction, e.g. from the first port 50 to the second port 52 or from the second port 52 to the first port 50.

[0022] The smaller diameter section 60 of the spool 14 has an axial length that is great enough so that a portion of the smaller diameter section 60 of the spool 14 still resides in the reduced diameter end section 42 of the bore 32 when the spool is in the open position (second operating position) thus allowing cross port communication between the first port 50 and the second port 52. This facilitates alignment of the spool 14 with respect to the cage 12 as the spool moves toward the closed position from the open position. In other words, a portion of the spool 14, e.g. a portion the smaller diameter section 60 between the distal end of the spool (and also the first port 50) and the apertures 90, can still contact cage 12, which aids in alignment of the spool with respect to the cage. This alignment feature can mitigate problems of ineffective sealing between the spool and the cage, which can be found in known bi-directional relief valves.

[0023] The bi-directional relief valve 10 includes biasing means urging the spool 14 towards the closed position where fluid flow is blocked through the radial apertures 90 in the spool between the passage 70 in the spool and the second port 52 of the cage 12. In the illustrated embodiment, the biasing means can be a spring 94 or a valve arrangement, which will be described in more detail below. [0024] The spring 94 contacts the spool 14 to urge the spool toward the closed position. In the illustrated embodiment, the spring 94 is a compression spring that is received in the spring counterbore 76 formed in the spool 14, i.e. the spring 94 contacts the spool. The spring counterbore 76 can have an axial length that is greater than 2/3 the length of the spring 94 measured in an axial direction. This aligns the biasing force of the spring 94 along the central axis of the spool 14.

[0025] The spring 94 is also restrained by a spring retainer 96, which is generally cylindrical. The spring retainer 96 includes a counterbore 98 that receives the spring 94. The spring retainer 96 is surrounded by a seal 102 that contacts the internal wall 36 of the bore 32 formed in the cage 12. This seal 102 confines any fluid disposed in the bore 32 to one side (a left side per the orientation shown in FIGURE 1 ) of the seal 102. The spring retainer 96 also includes an externally threaded section 104 that is radially inwardly offset from the internal wall 36 of the bore 32. The externally threaded section 104 cooperates with a first retaining nut 106 having an internally threaded section 108 and an externally threaded section 1 12.

[0026] A second retaining nut 1 14 including an internally threaded section 1 1 6 also threads onto the spring retainer 96. The first retaining nut 106 threads into the head 16 of the cage 12. The spring retainer 96 threads into the first retaining nut 106 and a second retaining nut 1 14 thus fixing the spring retainer axially and radially with respect to the cage 12. The spring retainer 96 includes a keyed recess 1 18 that allows a tool, e.g. an Allen wrench, to be inserted into the recess for threading the spring retainer 96 into the retaining nuts 106, 1 14. The biasing force of the spring 96 can be adjusted by threading the spring retainer 96 axially inwardly and outwardly from the bore 32. Accordingly, the pressure at which the spool 14 moves toward the open position, which will be described in more detail below, can be adjusted by adjusting the length of the spring 94. A cover 120 fits over the first retaining nut 106 and covers the first retaining nut and the second retaining nut 1 14.

[0027] As discussed above, the biasing means can also be a valve arrangement. The valve arrangement is configured to permit fluid pressure about equal to a fluid pressure of whichever port, e.g. port 50 or port 52, is at a lower pressure (whichever port is connected to the return line in the hydraulic system) to act against the spool to urge the spool toward the closed position. This valve arrangement can include first and second one - way check valves. For example, a first check ball 120 can be located in the passage 70 formed in the spool 14 and cooperate with the valve seat 74 to block flow of fluid in the rightward direction per the orientation shown in FIGURE 1 . A cage 124 can be inserted into the passage 70 to retain the ball 122 within the passage. A second check ball 126 can be disposed in the radial passage 78 and cooperates with the second valve seat 82 to block upward (per the orientation shown in FIGURE 1 ) flow of fluid through the radial passage 78. The second check ball 126 is retained in the radial passage 78 by the cage 12.

[0028] The check valve arrangement shown in FIGURE 1 can operate in the following manner. When the first inlet/outlet port 50 is operating as a high pressure supply line and the second inlet/outlet port 52 is operating as a low pressure return line, the high pressure fluid entering into the bore 32 of the cage 12 and the passage 70 of the spool 14 pushes the first check ball 122 toward the first check ball valve seat 74 to block flow through the passage 70. With the second inlet/outlet port 52 operating as the return line, the second check ball 126 moves away from the second valve seat 82 because of the low pressure at the second inlet/outlet port 52 and that the second inlet/outlet port is in the same annular channel 58 as the second radial openings 54. Accordingly, the fluid pressure acting against the valve spool 14 urging the valve spool toward the closed position (to the left per the orientation shown in FIGURE 1 ) is about equal to the fluid pressure of second inlet/outlet port 52, which is at a lower pressure than the first inlet/outlet port 50, and/or the biasing force of the spring 94 (if one is provided). Similarly, where the second inlet/outlet port 52 acts a high pressure supply line and the first inlet/outlet port 50 acts as a low pressure return line, high pressure fluid enters through the second radial apertures 54 to close the second check ball 126 against the second valve seat 82. Since the first inlet/outlet port 50 is at low pressure, as compared to the second inlet/outlet port 52, the first check ball 120 moves from the first valve seat 74 and the fluid pressure acting against the spool 14 is about equal to the fluid pressure at the first inlet/outlet port 50.

[0029] As explained above, the biasing means urges the spool 14 towards a closed position. The bi-directional relief valve 10 also includes a ring 134 connected with the cage 12 and extending into the bore 32. The spool 14 contacts the ring 134 when the spool is in the closed position (the first operating position) to retain the spool within the bore. When the operating pressure at the first inlet/outlet port 50 is great enough to overcome the biasing force of the biasing means, e.g. the spring 94 and/or the valve arrangement, fluid entering the bore 32 of the cage 12 in the passage 70 of the spool 14 can result in movement of the spool toward the central section 38 of the bore. When the spool 14 moves a great enough distance toward the central section 38 such that the radial apertures 90 are no longer blocked by the internal wall 36 of the bore 32, fluid can pass from the internal passage 70 of the spool 14 out the radial apertures 90 and out the radial openings 52 in the cage 12 to the return line of the hydraulic system. Where the second inlet/outlet port 52 is operating at higher pressure, if this pressure overcomes the biasing means fluid entering into the central section 38 of the bore 32 through the second inlet/outlet ports 52 presses against the shoulder 64 urging the spool 14 toward the open position where the radial apertures 90 are no longer blocked by the internal wall 36 of the bore 32. Accordingly, the bi-directional relief valve can provide pressure relief in either direction for the hydraulic circuit.

[0030] A bi-directional relief valve that can provide pressure relief for a hydraulic circuit operating in either direction has been described with particularity. Modifications and alterations will occur to those upon reading and understanding the preceding detailed description. The invention is not limited to only the embodiment(s) disclosed above. Instead, the invention is broadly defined by the appended claims and the equivalents thereof.

Claims

CLAIMS:

1 . A bi-directional relief valve comprising:

a cage including a bore, a first inlet/outlet port and a second inlet/outlet port, each port being connected with the bore and the bore including a central section having a first diameter and a reduced diameter section having a second diameter, which is smaller than the first diameter;

a spool located in the bore and movable with respect to the cage within the bore, the spool including a smaller diameter section received in the reduced diameter section of the bore and a larger diameter section received within the central section of the bore, the spool including a passage open to the first port and a radial aperture extending through the spool from the passage; and

biasing means urging the spool towards a closed position where fluid flow is blocked through the radial aperture between the passage and the second port, when the biasing force of the biasing means is overcome the spool moves toward an open position where the smaller diameter section of the spool moves toward the central section of the bore such that fluid flow is no longer blocked through the radial aperture between the passage and the second port.

2. The valve of claim 1 , further comprising a ring connected with the cage and extending into the bore, wherein the spool contacts the ring when the spool is in the closed position to retain the spool in the bore.

3. The valve of claim 1 , wherein the biasing means is a spring, wherein the spring contacts the spool.

4. The valve of claim 3, further comprising a spring retainer, the spring retainer includes a counterbore that receives the spring.

5. The valve of claim 4, wherein the counterbore has an axial length that is greater than 2/3 the length of the spring measured in an axial direction.

6. The valve of claim 1 , wherein the biasing means is a valve arrangement configured to permit fluid pressure about equal to a fluid pressure of whichever port is at a lower pressure to act against the spool to urge the spool toward the closed position.

7. The valve of claim 6, wherein the valve arrangement includes first and second one-way check valves.

8. The valve of claim 1 , wherein when the smaller diameter section of the spool moves toward the central section of the bore such that fluid flow is no longer blocked through the radial aperture between the passage and the second port, a portion of the smaller diameter section of the spool still remains in the reduced diameter section of the bore.

9. The valve of claim 8, wherein the portion of the smaller diameter section of the spool still remaining in the reduced diameter section is disposed between the radial aperture and the first port in an axial direction.

10. A bi-directional relief valve comprising:

a cage including a bore, a first inlet/outlet port and a second inlet/outlet port, each port being connected with the bore;

a spool located in the bore and movable with respect to the cage within the bore between a first operating position and a second operating position, the spool including a passage, the passage being open to the first port in both the first operating position and the second operating position, the passage being blocked with respect to the second port when in the first operating position and being open to the second port when in the second operating position; and

biasing means urging the spool towards the first operating position.

1 1 . The valve of claim 10, wherein at least a portion of the spool contacts the cage when in the first operating position and when in the second operating position.

12. The valve of claim 1 1 , wherein the spool includes a radial aperture connected with the passage, the radial aperture being blocked with respect to the second port when in the first operating position and being open to the second port when in the second operating position.

13. The valve of claim 1 2, wherein the portion of the spool contacting the cage when in the first operating position is disposed between the radial aperture and the first port in an axial direction.

14. The valve of claim 10, further comprising a ring connected with the cage and extending into the bore, wherein the spool contacts the ring when the spool is in the first operating position to retain the spool in the bore.

15. The valve of claim 10, wherein the biasing means is a spring, wherein the spring contacts the spool.

1 6. The valve of claim 15, further comprising a spring retainer, the spring retainer includes a counterbore that receives the spring.

17. The valve of claim 1 6, wherein the counterbore has an axial length that is greater than 2/3 the length of the spring measured in an axial direction.

18. The valve of claim 10, wherein the biasing means is a valve arrangement configured to permit fluid pressure about equal to a fluid pressure of whichever port is at a lower pressure to act against the spool to urge the spool toward the first operating position.

19. The valve of claim 18, wherein the valve arrangement includes first and second one-way check valves.