JP2006009844A - Counterbalance valve and hydraulic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a counterbalance valve capable of increasing the volumetric efficiency of a hydraulic motor by reducing the starting shock of the hydraulic motor and the hydraulic motor. <P>SOLUTION: A spool 15 comprises large diameter holes 17a and 17b, inner hole parts 18a and 18b, and small diameter holes 19a and 19b. Guide members 20a and 20b guiding check valves 26a and 26b are screwed liquid-tight into the large diameter holes 17a and 17b. The check valves 26a and 26b comprise valve stems 27a and 27b and valve bodies 28a and 28b. The bodies 28a and 28b comprise sloped surfaces 29a and 29b and projected parts 30a and 30b. The projected parts 30a and 30b are fittedly inserted into the inner hole parts 18a and 18b, slight clearances are formed between the inner diameters of the inner hole parts 18a and 18b and the outer diameters of the projected parts 30a and 30b, and the opening area of the clearance formed with the inner hole parts 18a and 18b and the projected parts 30a and 30b is extremely restricted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a counter balance valve provided in a traveling device and a hydraulic motor including the counter balance valve.

A traveling circuit for driving an excavator, which is a construction machine, includes a hydraulic pump that supplies pressure oil to the hydraulic motor, a control valve that switches a flow of the pressure oil supplied to the hydraulic motor, and stops and rotates the hydraulic motor. Is provided.
When driving the hydraulic motor, the pressure oil that has flowed through the traveling circuit and led to the hydraulic motor flows into one side port of the counter balance valve of the traveling circuit, and is connected to this port by a pipeline and built in the spool. It passes through the check valve and flows to the hydraulic motor to rotate the hydraulic motor. On the other hand, the pressure oil also flows into the spring chamber on the one-side port side, overcomes the spring force in the spring chamber located on the opposite side of the spool and moves the spool, and the return oil from the hydraulic motor receives the spool and counterbalance valve. The hydraulic motor rotates by flowing to the port on the other side through the pipeline.

In this type of running circuit, when the hydraulic motor is started by switching the control valve, the pressure oil suddenly flows into the counter balance valve and the hydraulic motor, a starting shock is generated when the shovel starts, and the operability of the shovel is deteriorated. The defect appears.
In order to solve the above problems, a buffer oil passage 25 having a throttle portion 24 is provided in the sliding spool 21 of the counter balance valve 20, and the buffer oil passage 25 is formed when the counter balance valve 20 is switched to the open position. The supply-side oil passage 28 and the discharge-side oil passage 29 are communicated with each other, and are allowed to flow out from the control valve 12 to the supply-side passage 29 (see, for example, Patent Document 1).

Further, when the counter balance valve 20 is switched to the open position, a drain oil port 20a communicating with the supply side passage 28 is provided in the counter balance valve 20, and the drain oil port 20a is a buffer oil having an on-off valve 32 and a throttle valve 31. A pilot operation circuit 33 is connected to the on-off valve 32 through a path 30 connected to the operation circuit 11. The pilot operation circuit 33 operates the on-off valve 32 to be closed by the pilot pressure from the operation circuit 11 after the counter balance valve 20 is switched to the open position (see, for example, Patent Document 2).
JP 2003-97699 A JP 2003-97701 A

However, in Patent Document 1, even when the counterbalance valve 20 is switched to the open position, the pressure oil on the supply-side oil passage side 28 continues to flow out to the discharge-side oil passage 29, resulting in loss of pressure oil, and the volumetric efficiency of the travel motor is increased. Deteriorate. In Patent Document 2, the number of parts increases and the cost increases.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a counter balance valve and a hydraulic motor that can avoid a start shock and improve the volumetric efficiency of a traveling motor. .

In order to achieve the above object, the present invention is a counterbalance valve comprising a spool reciprocally movable in the axial direction in a hole communicating with two ports through which pressure oil flows.
The check valve mechanism built in the spool is
A valve shaft member movably supported by the guide member;
A valve body having a protrusion provided at a tip of the valve shaft member and fitted into an inner hole of the spool;
With
An outer diameter of the protruding portion is provided slightly smaller than an inner diameter of the inner hole portion, and the protruding portion is inserted into the inner hole portion by contacting the inclined surface of the valve body with the end surface of the inner hole portion. The opening area of the gap between the protrusion and the inner hole is reduced at the beginning of the flow of pressure oil, and after the start of the flow of pressure oil, the protrusion is separated from the inner hole and the pressure oil is not restricted. .
According to the present invention, even if the pressure oil suddenly flows into the counter balance valve at the start-up, the opening area of the gap between the protrusion and the inner hole is reduced at the start of the flow, so that the pressure oil passing through the check valve mechanism is controlled. Accordingly, the flow of pressure oil into the hydraulic motor becomes gentle, and the start-up shock of the hydraulic motor can be reduced when starting.
Furthermore, according to the present invention, even if the pressure oil suddenly flows into the counter balance valve at the time of start-up, the flow of pressure oil to the hydraulic motor becomes gentle, and the start-up shock of the hydraulic motor can be reduced at the start, A hydraulic motor with good operability can be provided.

  In the present invention, since the opening area between the projecting portion and the inner hole portion is reduced at the start of the flow, the pressure oil passing through the check valve mechanism is controlled, and the flow of the pressure oil into the hydraulic motor becomes gradual, and the hydraulic motor at the start The starting shock can be reduced. Therefore, it is possible to provide a hydraulic motor with good operability.

Next, a counter balance valve according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a travel circuit of a hydraulic motor 9 using a counterbalance valve 10 according to an embodiment of the present invention.
The counter balance valve 10 has a pair of first ports 12a and 12b and a pair of second ports 13a and 13b defined on the upper and lower surfaces of the body 11 having a substantially rectangular parallelepiped shape, respectively, A spool 15 is slidably fitted into a hole 14 formed in the body 11 in the axial direction.
The spool 15 is formed with stepped holes 16a and 16b facing each other in the axial direction from both ends. The holes 16a and 16b include large diameter holes 17a and 17b, inner hole portions 18a and 18b, and small diameter holes 19a and 19b. Here, since the large diameter holes 17a, 17b, the inner hole portions 18a, 18b and the small diameter holes 19a, 19b have the same structure, the large diameter hole 17a, the inner hole portion 18a, and the small diameter hole 19a will be described. The inner hole portion 18b and the small diameter hole 19b are denoted by reference numerals and detailed description thereof is omitted.

A guide member 20a that guides the large-diameter hole 17a by inserting a check valve (check valve mechanism) 26a movably in the axial direction is screwed in a fluid-tight manner. The guide member 20a has a disc-shaped seating portion 21a at a substantially central portion in the axial direction, and boss portions 22a and 23a extending in the axial direction at both ends of the seating portion 21a, and the seating portion 21a. Is engaged with the end of the spool 15 via a screw mechanism (not indicated).
The boss portion 22a is accommodated in a pilot chamber 24a formed concentrically with the hole 14, and the boss portion 23a is fitted into the large-diameter hole 17a and screwed.
Further, a check valve 26a is mounted in the hole 25a of the guide member 20a. The check valve 26a includes a valve shaft (valve shaft member) 27a and a valve body 28a. The valve shaft 27a is slidably inserted into the hole 25a of the guide member 20a and is stored in the hole 25a. The member 31a is provided so as to be displaceable in the axial direction. The valve body 28a has an inclined surface 29a inclined inward in the axial direction, and a protruding portion 30a. When the hydraulic motor 41 is stopped, the inclined surface 29a of the check valve 26a is the end surface 15a of the inner hole portion 18a. The projecting portion 30a is formed so as to be fitted into the inner diameter portion 18a when it comes into contact with the inner diameter portion 18a, and there is a slight gap between the inner diameter of the inner hole portion 18a and the outer diameter of the projecting portion 30a. Therefore, the opening area of the gap formed by the inner hole portion 18a and the protruding portion 30a is reduced.

Further, in the check valve 26a, the protruding portion 30a of the valve main body 28a is fitted into the inner hole portion 18a by the elastic force of the spring member 31a, and the inclined surface 29a is pressed against the end surface 15a of the inner hole portion 18a.
The check valve 26a is displaced in the direction of the arrow X by the pressure oil, the protrusion 30a is separated from the small diameter hole 19a, the tip of the protrusion 30a is detached from the end surface 15a of the inner hole 18a, and the check valve 26a is In the fully opened state, the inclined surface 29a is separated from the end surface 15a, and the valve body 28a is displaced in the direction of the arrow X to the position where the valve body 28a is not engaged with the inner hole portion 18a, that is, into the large-diameter hole 17a. Do not squeeze.

Reference numeral 33a denotes a plug member that closes the pilot chamber 24a in a liquid-tight manner, and is screwed to the body 11. The spring member 35a is accommodated in the inner hole 34a of the plug member 33a. One end of the spring member 35a is seated on the bottom surface of the inner hole 34a of the plug member 33a, and the other end is seated on a spacer 32a engaged with the seating portion 21a. Therefore, the spool 15 is secured in a substantially central portion of the body 11 in a state where no pressure oil acts by the elastic force of the spring members 35a and 35b, that is, in a neutral position.
In the substantially central portion of the spool 15, annular grooves 37a and 37b extending in the axial direction are provided on the outer peripheral surface at intervals, and the annular grooves 37a and 37b communicate with the second ports 13a and 13b. 15 communicates with the small-diameter holes 19a and 19b through the communication holes 38a and 38b. In addition, communication holes 40a and 40b are formed in the radial direction in the holes of the large diameter holes 17a and 17b of the spool 15, and the communication holes 40a and 40b communicate with the first ports 12a and 12b. Yes.

The counterbalance valve 10 according to the embodiment of the present invention is basically configured as described above. Next, the operation thereof will be described.
First, as shown in FIG. 1, the hydraulic motor 41 is connected to the first ports 12 a and 12 b via the first supply / discharge passages 42 and 43. The second ports 13 a and 13 b are connected to the input ports A and B of the control valve 46 through the second supply / discharge passages 44 and 45. The hydraulic pump 47 is connected to the pressure port P and the tank port T of the control valve 46 through the supply passage 48, and the tank port T is connected to the tank 50 through the discharge passage 49.
In FIG. 1, when the control valve 46 is set to the neutral position, the hydraulic motor 41 is secured in a stopped state where no pressure oil is acting.
In this state, the counter balance valve 10 is held at the neutral position as shown in FIG. 1 by the spool 15 being biased by the elastic force of the spring members 35a and 35b. Further, in the check valves 26a and 26b, the inclined surfaces 29a and 29b of the valve bodies 28a and 28b are brought into contact with the end surfaces 15a and 15b of the inner hole portions 18a and 18b by the elastic force of the spring members 31a and 31b, and the protruding portion 30a. , 30b are inserted into the inner holes 18a, 18b.

  FIG. 2 shows a state in which the control valve 46 is switched from the neutral position to one direction, for example, the left position. As shown in FIG. 2, the control valve 46 is held in the activated state. In this state, the pressure oil generated by the hydraulic pump 47 passes through the second supply path 44 from the pressure port P of the control valve 46 through the supply passage 48 to the second port 13a, the annular groove 37a, and the communication hole 38a into the small diameter hole 19a. It flows in and acts on the valve body 28a of the check valve 26a. Thus, the pressure oil displaces the check valve 26a in the direction of the arrow X against the elastic force of the spring member 31a. Therefore, the pressure oil starts to flow to the hydraulic motor 41 from the first port 12a and the first supply path 42 through the large-diameter hole 17a and the communication hole 40a through the gap between the inner hole portion 18a and the protruding portion 30a. When the pressure oil starts to flow, when the check valve 26a is pushed open in the activated state and flows, a gap in which the opening area between the inner diameter of the inner hole portion 18a having a reduced opening area and the outer diameter of the projecting portion 30a is reduced is formed. Since it flows, the flow of the pressure oil flowing into the hydraulic motor 41 becomes gentle, so that the starting shock can be reduced at the start.

On the other hand, the pressure oil flowing from the input port A to the second supply / discharge passage 44 flows into the pilot chamber 24a from the pilot passage 52 through the third port 51a, and presses the guide member 20a in the direction of arrow Y. For this reason, the spool 15 is displaced in the arrow Y direction against the elastic force of the spring member 35b. Therefore, the pressure oil that has rotated the hydraulic motor 41 passes through the first port 12b from the first drain passage 43, the second port 13b from the annular groove 37b, and the tank port of the control valve 46 from the input port B through the second drain passage 45. T, return to the tank 50 from the discharge passage 49.
When the control valve 46 is returned to the neutral position, the pressure oil flowing into the input port A is shut off. For this reason, since the pressure in the pilot chamber 24a decreases, the spool 15 is displaced in the direction of the arrow X by the elastic force of the spring member 35b provided in the pilot chamber 24b, and becomes in the neutral state shown in FIG. Therefore, the pressure oil that has rotated the hydraulic motor 41 stops the rotation of the hydraulic motor 41 by the spool 15.

When the control valve 46 is switched from the neutral position to the right position, the pressure oil flows from the input port B, returns from the input port A, the flow of pressure oil is opposite to that described above, and the hydraulic motor 41 rotates in the opposite direction.
The counter balance valve 10 according to the embodiment of the present invention has been described in the case where the hydraulic motor 41 has a fixed capacity, but a variable capacity hydraulic motor may of course be used, and the same effect can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a schematic structure of a counterbalance valve according to an embodiment of the present invention and an explanatory diagram showing a running circuit using the counterbalance valve. It is operation | movement explanatory drawing of the traveling circuit using the counter balance valve which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Counter balance valve 11 Body 15 Spool 18a, 18b Inner hole part 26a, 26b Check valve 27a, 27b Valve shaft 28a, 28b Valve main body 29a, 29b Inclined surface 30a, 30b Protrusion part

Claims (2)

A counter balance valve having a spool reciprocating in the axial direction in a hole communicating with two ports through which pressure oil flows;
The check valve mechanism built in the spool is
A valve shaft member movably supported by the guide member;
A valve body having a protrusion provided at a tip of the valve shaft member and fitted into an inner hole of the spool;
With
An outer diameter of the protruding portion is provided slightly smaller than an inner diameter of the inner hole portion, and the protruding portion is inserted into the inner hole portion by contacting the inclined surface of the valve body with the end surface of the inner hole portion. The opening area of the gap between the protrusion and the inner hole is reduced at the beginning of the flow of pressure oil, and after the start of the flow of pressure oil, the protrusion is separated from the inner hole and the pressure oil is not restricted. Counter balance valve. A hydraulic motor comprising the counterbalance valve according to claim 1.

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