JP5822232B2 - Switching valve - Google Patents

Description

  The present invention relates to a switching valve that maintains a switching position for supplying hydraulic oil to a cylinder chamber when the cylinder is lowered by its own weight, for example.

  As this type of switching valve, the one described in Patent Document 1 has been conventionally known. In this conventional switching valve, the outer diameter of the center land is slightly smaller than the inner diameter of the spool hole, and a bleed-off gap is formed between the spool hole and the center land.

  Therefore, in this conventional switching valve, the bleed-off function is exhibited through the gap even when the spool is switched to the left or right.

Utility Model Registration No. 2515912

However, depending on the application of the switching valve, it may be required to bleed off only when the spool is switched to one side. However, the conventional switching valve cannot meet the requirement.
An object of the present invention is to provide a switching valve that exhibits a bleed-off function only when the switching valve is switched to one side.

  According to the present invention, a spool hole is formed in the valve body, a first annular groove communicating with the pump is formed around the spool hole, and second and second tanks communicating with the tank on both sides of the first annular groove are provided. Three annular grooves and a spool slidably incorporated in the spool hole are provided.

  On the other hand, when the spool is in the neutral position, the first land portion maintaining the positional relationship corresponding to the first annular groove and the second and third land portions formed on both sides of the first land portion are provided. And when the spool is in a neutral position, the tank communicates with the first annular groove communicating with the pump via an annular recess formed between the first land portion and the third land portion. The third annular groove communicates with the second land groove, and the communication between the first annular groove and the second annular groove is blocked by the second land portion.

  Further, when the spool is switched to one switching position, the hydraulic oil from the pump guided to the first annular groove is guided to the actuator from one actuator port formed in the valve body, and the spool is switched to the other switching position. When switched to the position, the hydraulic oil from the pump guided to the first annular groove is guided to the actuator from the other actuator port formed in the valve body.

  In the switching valve of the first invention, the second land portion is composed of a pair of annular convex portions, and an annular concave portion is formed between the pair of annular convex portions, while a throttle passage is formed in one annular convex portion. When the spool is switched to the one switching position, the first annular groove communicated with the pump is communicated with the second annular groove via the throttle passage.

  The second invention is characterized in that the throttle passage formed in the one annular convex portion is composed of a throttle groove formed in the outer periphery of the one annular convex portion.

  The third invention is characterized in that the throttle passage formed in the one annular convex portion is composed of small holes formed in the outer periphery of the one annular convex portion.

  According to a fourth aspect of the present invention, an outer diameter of the one annular convex portion is made smaller than an inner diameter of the spool hole, and a gap is formed between the annular convex portion and the inner diameter of the spool hole. It is characterized in that it is a throttle passage formed in the annular convex portion.

  In any one of the first to fourth inventions, when the spool is held at one of the switching positions, the first annular groove communicated with the pump becomes the second annular groove communicated with the tank and the one annular convex portion. Since communication is established through the formed throttle passage, the bleed-off function is exhibited only at one of the switching positions.

  According to the second invention, since the throttle passage formed in the one annular convex portion is constituted by the throttle groove formed in the outer periphery of the annular convex portion, the processing of the throttle passage is simplified.

It is sectional drawing when a spool exists in a neutral position. It is sectional drawing when a spool exists in the other switching position. It is sectional drawing when a spool exists in one switching position.

  In the illustrated embodiment, a spool hole 2 is formed in the valve body 1, and a spool 3 is slidably incorporated in the spool hole 2. Then, both ends of the spool 3 face the pilot chambers 4 and 5, and one pilot chamber 4 is provided with a centering spring 6. By the action of the centering spring 6, the spool 3 is normally neutral as shown in FIG. The position is maintained.

  The first to seventh annular grooves 7 to 13 are formed around the spool hole 2, and the first annular groove 7 communicates with a pump (not shown) and the second and third annular grooves. 8 and 9 communicate with a tank (not shown). The fourth and fifth annular grooves 10 and 11 communicate with the bridge passage 14. The bridge passage 14 communicates with the first annular groove 7 via a load check valve 15.

  Furthermore, the valve body 1 is formed with a sixth annular groove 12 communicating with the first actuator port 16 and a seventh annular groove 13 communicating with the second actuator port 17. The first actuator port 16 communicates with the rod side chamber C1 of the cylinder C, and the second actuator port 17 communicates with the head side chamber C2 of the cylinder C.

  On the other hand, the spool 3 is formed with a first land portion 20 at substantially the center thereof, and second and third land portions 21 and 22 are formed on both sides of the first land portion 20. A first annular recess 23 is defined between the first land portion 21 and the second land portion 21, and a second annular recess 24 is defined between the first land portion 20 and the third land portion 22.

  Further, the second land portion 21 is composed of a pair of annular convex portions 21a and 21b as shown in the figure, and the annular convex portion 21b includes an annular concave portion 25 between the annular convex portions 21a and 21b. A throttle groove 26 constituting the throttle passage of the present invention is formed. In this embodiment, since the throttle groove 26 is formed in the annular convex portion 21b, for example, processing is easier than in the case where a small hole is formed in the annular convex portion 21b.

  However, if workability is not taken into consideration, a small hole may be formed in the annular convex portion 21b, and the small hole may be used as a throttle passage. Alternatively, the outer diameter of the annular convex portion 21b may be smaller than the inner diameter of the spool hole 2, and the gap formed between the annular convex portion 21b and the inner diameter of the spool hole 2 may be used as a throttle passage.

  The spool 3 is formed with fourth and fifth land portions 27 and 28 outside the second and third land portions 21 and 22, and a third annular recess 29 is formed between the second and fourth land portions 21 and 27. The fourth annular recess 30 is formed between the third and fifth land portions 22 and 28. Further, the sixth and seventh land portions 31 and 32 are formed outside the fourth and fifth land portions 27 and 28, and the fifth annular recess 33 is formed between the fourth and sixth land portions 27 and 31. A sixth annular recess 34 is formed between the fifth and seventh land portions 28 and 32.

If the spool 3 is in the neutral position shown in FIG. 1 under the above configuration, the communication between the first and second annular grooves 7 and 8 is blocked by the annular convex portion 21a of the second land portion 21. At the same time, the first and third annular grooves 7 and 9 communicate with each other via the second annular recess 24.
Accordingly, in this neutral position, the pump discharge oil guided to the first annular groove 7 is returned to the tank through the third annular groove 9.

In the neutral position, the bridge passage 14 and the tank passages 18 and 19 are disconnected from the sixth and seventh annular grooves 12 and 13, so the first and second actuator ports 16 and 17 are closed. The cylinder C connected to the first and second actuator ports 16 and 17 holds the current position.
In the figure, reference numerals 36 and 37 denote relief holes for providing relief valves (not shown), and 38 and 39 denote holes for providing plugs (not shown).

  When the pilot pressure is guided to the pilot chamber 5 from the above state and the spool 3 is switched to the left switching position shown in FIG. 2, the first annular groove 7 and the second annular groove 8 are caused by the first and third land portions 20 and 22. The communication between the first annular groove 7 and the third annular groove 9 is closed, and the load check valve 15 is opened so that the first annular groove 7 and the bridge passage 14 communicate with each other. The bridge passage 14 communicates with the second actuator port 17 via the fifth annular groove 11, the sixth annular recess 34, and the seventh annular groove 13. The left switching position of the spool 3 shown in FIG. 2 is the other switching position of the present invention.

  At this time, the first actuator port 16 communicates with the tank passage 18 through the notch 35 formed in the sixth annular groove 12, the fifth annular recess 33, and the sixth land portion 31, and therefore, from the rod side chamber C1 of the cylinder C. Is returned to the tank via the tank passage 18. Therefore, the cylinder C extends while holding the load.

  On the other hand, when pilot pressure is guided to the pilot chamber 4 and the spool 3 is switched to the right switching position shown in FIG. 3, the second actuator port 17 is connected to the tank passage via the seventh annular groove 13 and the sixth annular recess 34. Since the head side chamber C2 of the cylinder C communicates with the tank through the tank passage 19, the cylinder C contracts by its own weight. The right switching position of the spool 3 shown in FIG. 3 is one switching position of the present invention.

  At this time, the first annular groove 7 is closed by the annular protrusions 21b of the first land portion 20 and the second land portion 21. Since the annular protrusion 21b is formed with a throttle groove 26, the first annular groove 7b is formed. The groove 7 communicates with the tank via the throttle groove 26, the third annular recess 29 and the second annular groove 8. The pump discharge oil guided to the first annular groove 7 in this way is guided to the tank via the throttle groove 26, so that the pressure corresponding to the pressure loss when passing through the throttle groove 26 is the first annular groove. It occurs on the 7th side.

  When the spool 3 is switched to the right switching position as described above, the bridge passage 14 passes through the fourth annular groove 10, the fifth annular recess 33, and the sixth annular groove 12, and thereby the first actuator port 16. Therefore, the pressure loss generated by the throttle groove 26 as described above is guided to the rod side chamber C1 of the cylinder C, and the pressure loss pressure acts on the rod side chamber C1 of the cylinder C. Therefore, a force based on the product of the pressure loss and the pressure receiving area acts on the head side chamber C2 of the cylinder C.

  According to the switching valve of this embodiment, since the bleed-off function can be exhibited only when the spool 3 is switched to the right switching position shown in FIG. 3, the bleed only when the switching valve is switched to one switching position. It is possible to meet the demand for the off function.

  It is optimal for a hydraulic system that exhibits a bleed-off function only when the switching valve is switched to one switching position.

DESCRIPTION OF SYMBOLS 1 Valve body 3 Spool 7-13 1st-7 annular groove 16 1st actuator port 17 2nd actuator port 18 Tank passage 20 1st land part 21 2nd land part 21a Annular convex part 21b Annular convex part 26 Restriction groove

Claims (4)

  A spool hole is formed in the valve body. Around the spool hole, there are a first annular groove communicating with the pump and second and third annular grooves on both sides of the first annular groove and communicating with the tank. And a spool that is slidably incorporated in the spool hole, and the spool has a first land portion that maintains a positional relationship corresponding to the first annular groove when it is in a neutral position; Second and third land portions formed on both sides of the first land portion, and an annular recess formed between the first land portion and the third land portion when the spool is in a neutral position. The first annular groove communicating with the pump through the third annular groove communicating with the tank communicates with the second land portion, and the communication between the first annular groove and the second annular groove is blocked by the second land portion. On the other hand, the above spool When the switching position is switched, the hydraulic fluid from the pump guided to the first annular groove is guided to the actuator from one actuator port formed in the valve body, and the spool is switched to the other switching position. The switching valve is configured to guide the hydraulic oil from the pump guided to the first annular groove to the actuator from the other actuator port formed in the valve body, and the second land portion includes a pair of annular valves. An annular recess is formed between the pair of annular projections, and a throttle passage is formed in one of the annular projections. When the spool is switched to the one switching position, the pump communicates with the pump. A switching valve configured to communicate the first annular groove with the second annular groove via the throttle passage.   2. The switching valve according to claim 1, wherein the throttle passage formed in the one annular convex portion includes a throttle groove formed in an outer periphery of the one annular convex portion.   2. The switching valve according to claim 1, wherein the throttle passage formed in the one annular convex portion includes a small hole formed in an outer periphery of the one annular convex portion.   The outer diameter of the one annular convex portion is made smaller than the inner diameter of the spool hole, and a gap formed between the one annular convex portion and the inner diameter of the spool hole is formed in the one annular convex portion. The switching valve according to claim 1, wherein the switching passage is formed.

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