JP2009074664A - Shuttle valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the volumetric efficiency of an HST by preventing leakage from a high-pressure side to a cooler circuit in a shuttle valve. <P>SOLUTION: The shuttle valve 10 has a stepped hole 12 drilled on a main body 11, and a spool 13 slidably fitted into the stepped hole 12. Two inlets 26, 27, and one outlet 28 are arranged on the main body 11. Stepped spools 13a, 13b are slidably fitted into the stepped hole 12. Spring members 18a, 18b are loosely inserted into projection sections 19a, 19b arranged on a large-diameter sections 20a, 20b of the stepped spools 13a, 13b. Shaft sections 23, 24 are formed on a middle-diameter sections 21a, 21b, the shaft sections 23, 24 are slidably inserted each other, and the stepped spools 13a, 13b are connected with resilient force of the spring members 18a, 18b at a pushed state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shuttle valve used for a hydraulic continuously variable transmission, a hydrostatic transmission (HST), a hydraulic closed circuit, and the like.

Conventionally, in a hydrostatic transmission (HST) that is a hydraulic transmission device and a closed circuit, when the temperature of hydraulic oil on the closed circuit rises and foreign matter in the oil is removed, the oil on the low pressure side of the circuit is communicated to a cooler or a filter. Therefore, a shuttle valve is used (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-125331 (FIG. 8)

However, as shown in FIG. 8 of Patent Document 1, the shuttle valve uses a spool type as shown in Patent Document 1, but the clearance between the spool and the main body is set to a clearance, for example, 10 to 30 μm. Since the oil is leaked from the high pressure side to the cooler circuit, the leakage generates heat and the oil temperature rises, accelerating the oxidation of the oil and shortening the life of the oil and HST, and the volume of the HST. There is a problem of inefficiency.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a shuttle valve that prevents the leakage of oil from the high-pressure side to the cooler circuit and improves the volumetric efficiency of HST.

In order to solve the above-mentioned problem, the invention according to claim 1 has first and second two inlets and one common outlet, and the outlet is one of the inlets by the action of the inlet pressure. In the shuttle valve connected to
The body,
A first stepped spool slidably fitted into the body;
A second stepped spool that is coaxially provided opposite to the first stepped spool and is slidably fitted into the main body;
A first spring member provided in contact with the large diameter portion of the first stepped spool;
A second spring member provided in contact with the large diameter portion of the second stepped spool facing the first spring member;
With
The first and second stepped spools are pressed by the first and second spring members and are inserted into each other without any effort.
According to the present invention, the spool can move smoothly by sliding on the large diameter portion, and the first stepped spool and the second stepped spool can be prevented from being separated by the spring member. The spool is positioned in the center by the spring member.

According to a second aspect of the present invention, the first and second stepped spools are engaged with a tapered surface formed on the main body with an end surface of an intermediate diameter portion adjacent to the large diameter portion formed at an edge portion. Therefore, it is preferable because the leakage of the pressure oil can be reliably blocked. Furthermore, since the edge portion and the tapered surface are engaged, the higher the pressure, the higher the sealing performance, and the oil can be shut off reliably.
According to a third aspect of the present invention, since a shaft member is formed at the middle diameter portion and the shaft members are slidably inserted into each other, they can move together and no malfunction occurs. Also, the machining of the main body can be performed because the machining of the medium-diameter hole, which is the first stepped spool hole, and the small-diameter hole, which is the second stepped spool hole, is unnecessary, and the machining cost can be reduced.

  According to the present invention, it is possible to reliably seal without leakage even at high pressure with a simple structure without high-precision processing.

Hereinafter, preferred embodiments of the shuttle valve of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic longitudinal sectional view showing a schematic structure of a shuttle valve 10 according to an embodiment of the present invention. In FIG. 1, the shuttle valve 10 includes a stepped hole 12 drilled in the axial direction of the main body 11 (in the directions of arrows X and Y in FIG. 1), and a spool 13 slidably fitted in the stepped hole 12. And comprising.
The stepped hole 12 includes large-diameter holes 14a and 14b, and medium-diameter holes 15a and 15b that are provided coaxially with the large-diameter holes 14a and 14b and are formed adjacent to end surfaces of the large-diameter holes 14a and 14b. The small-diameter holes 16 provided in the medium-diameter holes 15a and 15b and formed adjacent to the end surfaces of the medium-diameter holes 15a and 15b are formed so as to be coaxially opposed and communicated in this order. The large diameter holes 14a and 14b and the medium diameter holes 15a and 15b have the same diameter, and the medium diameter holes 15a and 15b are smaller in diameter than the large diameter holes 14a and 14b. Further, the large-diameter holes 14a, 14b and the medium-diameter holes 15a, 15b communicate with each other in a stepped shape by the side wall surface, and the joint surfaces of the medium-diameter holes 15a, 15b and the small-diameter hole 16 are tapered surfaces 17a, 17b. Is formed. The large diameter holes 14a and 14b function as an oil chamber.

The spool 13 is formed of stepped spools 13a and 13b. The stepped spool 13a protrudes in the axial direction with respect to the large-diameter hole 14a and is loosely inserted into the medium-diameter hole 15a with a thickness in the axial direction so that the spring member 18a is loosely inserted. A large-diameter portion 20a, and an intermediate-diameter portion 21a that is provided adjacent to the large-diameter portion 20a and that has an end surface that is stepped, and that is provided with an edge portion 22a and engages the tapered surface 17a. A shaft portion 23 which is joined to the medium diameter portion 21a and protrudes from the small diameter hole 16.
On the other hand, the stepped spool 13b protrudes in the axial direction with respect to the large-diameter hole 14b and is loosely inserted into the medium-diameter hole 15b with a thickness in the axial direction so that the spring member 18b is inserted freely. A large-diameter portion 20b joined to the portion 19b, and a medium-diameter portion 21b that is provided adjacent to the large-diameter portion 20b, has an end surface formed in a stepped shape, and an edge portion 22b is provided in the stepped portion to engage the tapered surface 17b. And a shaft portion 24 that is joined to the medium diameter portion 21b, protrudes into the small diameter hole 16, and is fitted to the shaft portion 23.
The shaft portion 23 is fitted into the hole portion 25 of the shaft portion 24 and is formed to be slidable with each other. However, a hole portion (not shown) may be provided in the shaft portion 23 to insert the shaft portion 24.

The elastic force of each of the spring members 18a and 18b urges the stepped spools 13a and 13b, and pushes the stepped spools 13a and 13b so as not to separate from each other via the shaft portions 23 and 24. Is provided.
The large-diameter holes 14a and 14b and the small-diameter hole 16 formed in the main body 11 are provided with pressure oil supply paths 26 (26a) and 27 (27a) that are drilled in the main body 11 and connected to a pressure oil supply source (not shown). The small diameter hole 16 communicates with a supply path 28 connected to a cooler or a tank (not shown).

The shuttle valve 10 according to the embodiment of the present invention is basically configured as described above. Next, the operation will be described. 2 to 4 are explanatory views of the operation of the shuttle valve 10.
FIG. 2 shows a state in which the pressure oil supplied to the pressure oil supply paths 26 and 27 is the same pressure. In this case, the stepped spools 13 a and 13 b are returned to the center of the shuttle valve 10, that is, approximately the center of the small diameter hole 16 by the elastic force of the spring members 18 a and 18 b. Therefore, each of the pressure oil supply passages 26 and 27 communicating with the stepped spools 13a and 13b has a tank port (not shown) between the edge portions 22a and 22b of the medium diameter portions 21a and 21b and the tapered surfaces 17a and 17b. It communicates with a supply path 28 that communicates with (not shown).

FIG. 3 shows a state in which the pressure oil supply path 26 is at a higher pressure than the pressure oil supply path 27. That is, when high-pressure oil flows through the pressure oil supply passages 26 and 26a and flows into the large-diameter hole 14a and acts on the side wall surface of the large-diameter portion 20a, the spool 13a is displaced in the arrow Y direction. Thereby, the edge part 22a of the medium diameter part 21a contacts the taper surface 17a, and seals the pressure oil flowing into the pressure oil supply path 26.
On the other hand, since the shaft portion 23 of the spool 13a is engaged through the hole 25 of the shaft portion 24 of the spool 13b, the spool 13b is displaced in the direction of the arrow X in cooperation with the spool 13a, and the tapered surface 17b. A gap is generated between the edge portion 22b of the medium diameter portion 21b. Therefore, the pressure oil flowing into the pressure oil supply path 27 flows from the supply path 28 to a cooler or a tank (not shown) through the small diameter hole 16 through the gap between the tapered surface 17b and the edge portion 22b.

FIG. 4 shows a state in which the pressure oil supply path 27 is at a higher pressure than the pressure oil supply path 26. In this state, when high-pressure oil flows through the oil supply passages 27 and 27a and flows into the large-diameter hole 14b and acts on the side wall surface of the large-diameter portion 20b, the spool 13b is displaced in the arrow X direction. Thereby, the edge part 22b of the medium diameter part 21b contacts the taper surface 17b, and seals the pressure oil flowing into the pressure oil supply path 27.
Therefore, the spool 13a is displaced in the direction of the arrow X in cooperation with the spool 13b, and a gap is generated between the tapered surface 17a and the edge portion 22a of the medium diameter portion 21a. Therefore, the pressure oil flowing into the pressure oil supply path 28 flows from the supply path 28 to a cooler or a tank (not shown) through the small diameter hole 16 through the gap between the tapered surface 17a and the edge portion 22a.

FIG. 5 shows a hydraulic control apparatus 30 using the shuttle valve 10 according to the embodiment of the present invention.
The hydraulic control device 30 basically includes a pump 31, an actuator motor 32, a shuttle valve 35 connected to the pump 31 and the motor 32 via an A port 33 and a B port 34, and the shuttle valve 35. And a pressure control valve 37 provided downstream of the tank port 36.
The pressure control valve 37 communicates with a boost pump 38 that prevents the pressure on the low pressure side from dropping. The hydraulic control device 30 is provided with safety valves 39 and 40, check valves 41 and 42, a throttle 43, a filter 44, a cooler 45, and the like.

Next, the operation of the hydraulic control device 30 will be described.
When the pump 31 discharges to the A port 33 side, the A port 33 side becomes a high pressure and the motor 32 is rotated. At that time, since the A port 33 of the shuttle valve 35 is high pressure, the low pressure B port 34 communicates with the tank port 36 of the shuttle valve 35.
On the other hand, the pressure oil in the B port 34 flows through the shuttle valve 35 and the throttle 43, flows through the pressure control valve 37, enters the cooler 45 through the filter 44, and is cooled. Since the pressure oil is discharged from the B port 34, the cooled pressure oil from the boost pump 38 is supplied through the check valve 41, and the oil temperature in the circuit is kept at a low temperature.

  When the pump 31 discharges to the B port 34 side, since the B port 34 side becomes high pressure, the low pressure A port 33 communicates with the tank port 36 of the shuttle valve 35, so that the pressure oil flows from the A port 33 side to the shuttle valve. 35, the throttle 43, the pressure control valve 37, the filter 44, and the cooler 45 are cooled.

1 is a schematic longitudinal sectional view of a shuttle valve according to an embodiment of the present invention. It is operation | movement explanatory drawing of a shuttle valve in case the pressure oil which acts on the stepped spools 13a and 13b of FIG. 1 is the same pressure. It is operation | movement explanatory drawing of a shuttle valve when a high pressure acts on the stepped spool 13a of FIG. It is operation | movement explanatory drawing of a shuttle valve when a high pressure acts on the stepped spool 13b of FIG. It is a circuit diagram of the hydraulic control apparatus using a shuttle valve.

Explanation of symbols

10 Shuttle valve 11 Body 12 Stepped hole 13, 13a, 13b Stepped spool 14a, 14b Large diameter hole 15a, 15b Medium diameter hole 17a, 17b Tapered surface 22a. 22b Edge part

Claims (3)

A shuttle valve having a first and a second two inlets and a common outlet, the outlet being connected to one of the inlets by the action of the inlet pressure;
The body,
A first stepped spool slidably fitted into the body;
A second stepped spool that is coaxially provided opposite to the first stepped spool and is slidably fitted into the main body;
A first spring member provided in contact with the large diameter portion of the first stepped spool;
A second spring member provided in contact with the large diameter portion of the second stepped spool facing the first spring member;
With
The shuttle valve according to claim 1, wherein the first and second stepped spools are pressed by the first and second spring members and are inserted into each other. The shuttle valve according to claim 1, wherein
The first and second stepped spools are shuttle valves characterized in that an end surface of a medium diameter portion adjacent to the large diameter portion is formed at an edge portion and engages with a tapered surface formed in the main body. The shuttle valve according to claim 1 or 2,
A shuttle valve characterized in that a shaft member is formed in the middle diameter portion, and the shaft members are slidably inserted into each other.

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