JPH10299710A - Pilot control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure desired operating force reduced in a fine operation stroke range of an operating member by forming a spring member for determining operating force of the operating member controlling a pilot pressure control mechanism by a nonlinear coil spring. SOLUTION: When an operating lever 6 is operated from a neutral location around a pin 9 in the direction shown by the arrow F, a working plate 7 penetrates a receiving member 22 downward against a coil spring 29 for determining operating force which is made of a nonlinear coil spring via a push rod 12. When a spool 14 is descended by a prescribed distance by following this penetration, a spool land 14a interrupts a channel between fluid pressure chambers 20, 40. By the descending of a spool land 14b, pressure fluid from a pilot pressure supply source 30 is fed from a fluid pressure chamber 18 to a fluid pressure chamber 20 and fluid pressure of the fluid pressure chamber 20 ascends. By this pilot secondary pressure, a control valve 38 is switched from a neutral state to a left location and an actuator is operated and controlled so as to be nonlinearly changed for stroke of the operating lever 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot control valve for controlling the operation of a control valve or the like in a construction machine such as a hydraulic shovel by a pilot secondary pressure.

[0002]

2. Description of the Related Art Conventionally, in a construction machine such as a hydraulic excavator, a pilot control valve (remote control valve) using a fluid pressure such as hydraulic pressure has been used in order to remotely control a control valve for operating and controlling an actuator. Widely used. For example, a pilot control valve disclosed in Japanese Patent Application Laid-Open No. 2-154801 has a valve housing, an operation lever, and four pilot pressure control mechanisms. An operation lever operated by an operator is provided on the valve housing. The operation of each pilot pressure control mechanism having substantially the same configuration is controlled by an operation lever. Each of the pilot pressure control mechanisms is provided on the valve housing and is provided between the valve housing and the push rod within the valve housing, and a push rod that is pushed in conjunction with the operation lever.
There is provided a coil spring for determining the operating force of the operating lever, and a spool disposed to be relatively movable with respect to the push rod by a predetermined range via the coil for determining the secondary pressure of the pilot. This spool connects the pilot port of the control valve and the drain tank when the operation lever is not operated,
In operation, the pilot port is configured to communicate with the pilot pressure supply source.

[0003]

In the above-mentioned conventional pilot control valve, the reaction force for returning the operation lever to neutral, that is, the operation force determination coil spring for determining the operation force of the operation lever, is formed of a uniform pitch linear coil spring. It is configured. Therefore, the operating force of the operating lever changes linearly in proportion to the stroke of the operating lever (2 in FIG. 3).
See dotted line). As a result, the operating force of the operating lever in the fine operation stroke range becomes relatively strong, and the fine operation stroke range is relatively frequently used, so that the burden on the operator is not small. Due to this, in the above-mentioned conventional pilot control valve,
In particular, in some cases, good operation feeling was not obtained in the fine operation stroke range.

The present invention has been made based on the above-mentioned facts, and a main object of the present invention is to provide an improved operation force capable of obtaining a desired operation force which is reduced as compared with the prior art in a fine operation stroke range of an operation member. The purpose is to provide a pilot control valve.

[0005]

According to the present invention, there is provided an operating member provided in a valve housing and operated by an operator, and a pilot pressure control mechanism operated and controlled by the operating member. A mechanism provided in the valve housing and pushed in conjunction with the operating member; and a mechanism provided in the valve housing between the valve housing and the push rod.
An operating force determining spring member of the operating member, a pilot secondary pressure determining spring member and a operating force determining spring member of the operating member are relatively movably disposed within a predetermined range with respect to the push rod. A pilot control device configured to communicate the pilot port of the control valve with the drain tank when the operation member is not operated, and to communicate the pilot port with a pilot pressure supply source when the operation member is operated. A pilot control valve is provided, wherein the operating force determining spring member is constituted by a non-linear coil spring.

In the above invention, since the operating force determining spring member is constituted by a non-linear coil spring, the operating force of the operating lever varies in a non-linear manner shown as a curve bulging downward with respect to the stroke of the operating lever. Becomes Since the gradient of the increase in the operation force in the fine operation stroke range is relatively small and changes smoothly, the operation force of the operation lever in the fine operation stroke range is reduced as compared with the related art, and the burden on the operator is reduced. Due to this, the operation feeling, particularly the operation feeling in the fine operation stroke range is improved. In addition, the fine operation requires a larger operation lever stroke even with the same push rod stroke as compared with the conventional operation, so that a full stroke is frequently used, and a work amount emphasis that does not require much fine operation is performed. In this case, the lever operation is heavy and matches the operator's feeling, and the operation feeling is also improved in this aspect.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pilot control valve constructed according to the present invention will be described below with reference to FIGS. This pilot control valve can be suitably used for a construction machine, for example, a hydraulic shovel.

Referring to FIG. 1, the pilot control valve includes a valve housing, generally designated by the numeral 2.
A joint member 4 is screwed into an upper central portion of the valve housing 2. The lower end of the operating lever 6 is connected to the upper end of the joint member 4. An operation plate 7 is fixed to a lower end of the operation lever 6 serving as an operation member, and a protective boot 8 is disposed so as to cover a connection portion between the operation lever 6 and the joint member 4. The operating lever 6 is a pin that is rotatable about the pin 9 in the left-right direction in FIG. (Not shown), it is free to turn in a direction perpendicular to the plane of the drawing (left and right as viewed from the driver's seat). The valve housing 2, that is, the operation lever 6 is disposed on the left and right sides of the driver's seat, and the operation lever 6 shown in FIGS. 1 and 2 is disposed on the right side thereof.

In connection with the fact that the operating lever 6 is pivotable in the horizontal direction in FIG. 1 and in the direction perpendicular to the plane of the drawing, four pilot pressure control mechanisms 10 are provided in the valve housing 2.
a, 10b, 10c and 10d are arranged, and in FIG. 1, two pilot pressure control mechanisms 10a and 10b which are operated via the action plate 7 when the operation lever 6 is turned in the left-right direction of FIG. Only shown. The other two pilot pressure control mechanisms 10c and 10d, not shown, are actuated via the action plate 7 when the operation lever 6 is turned in the direction perpendicular to the paper surface in FIG. Four pilot pressure control mechanisms 10a, 10b, 10c and 1
0d has substantially the same configuration. Hereinafter, the pilot pressure control mechanism 10a, which is one of them, will be mainly described. The pilot pressure control mechanism 10a includes the push rod 1
2 and a spool 14.

A short cylindrical member 16 is mounted on the valve housing 2, and the push rod 12 is mounted on the cylindrical member 16 so as to be vertically movable. In the valve housing 2, a first fluid pressure chamber 18 and a second fluid pressure chamber 20 are provided.
And the spool 14 is provided with these first fluid pressure chambers 18.
And the second fluid pressure chamber 20. The upper end of the spool 14 is provided with a head, while the lower end of the push rod 12 is provided with a receiving recess. The receiving recess is formed by a hole whose lower end is open and whose upper end is closed. In the lower end of the receiving recess, the head is relatively movably received within a predetermined range. This spool 1
A receiving member 22 is disposed on the head of the actuator 4 and a coil spring 24 for determining the operating force of the operating lever 6 is interposed between the receiving member 22 and the valve housing 2.
A coil spring 26 for determining a pilot secondary pressure is interposed between the coil spring 26 and the spool land 14a of the spool 14.
The operating force determining coil spring 24 is formed of a non-linear coil spring, in this embodiment, an unequal pitch coil spring. Then, the operating force determining coil spring 24 biases the receiving member 22 upward with respect to the valve housing 2 and causes the receiving member 22 to abut on the lower surface of the push rod 12. The coil spring 26 for determining the pilot secondary pressure is connected to the receiving member 2.
2, the spool 14 is biased downward, and the head of the spool 14 is brought into contact with the upper surface of the receiving member 22.

The first fluid pressure chamber 18 is connected via a flow path 28 to a pilot pressure supply 30 such as a pilot hydraulic pump. A relief valve 34 is provided in the flow path 28 via a flow path 32. The relief valve 34 is connected to the flow path 28.
When the internal fluid pressure reaches a predetermined pressure, it is opened to return a fluid such as pressurized oil in the flow path 28 to the drain tank T and maintain the fluid pressure in the flow path 28 at a predetermined pressure. Further, the second fluid pressure chamber 20 is connected to one pilot port of the control valve 38 via the flow path 36. Further, the fluid pressure chambers 40 and 42 provided in the valve housing 2 are connected to the drain tank T via respective flow paths.

The spool 14 communicates with one of the pilot ports of the control valve 38 and the drain tank T when the operating lever 6 is not operated, and communicates with the pilot port and the pilot pressure supply 30 when the operating lever 6 is operated. I have.
Such a configuration is, specifically, the spool lands 14a and 1a formed on the spool 14 at axial intervals.
4b and a groove having a smaller diameter than those formed between the spool lands 14a and 14b. Spool land 14
The pressure receiving area a is formed larger than the pressure receiving area of the spool land 14b. That is, the diameter of the spool land 14a is larger than that of the spool land 14b. The end of the spool land 14b is positioned so as to face the fluid pressure chamber 42. Therefore, the free end of the spool land 14b is always in communication with the drain tank T.

In the pilot pressure control mechanism 10b, the second fluid pressure chamber 20 is provided in the pilot pressure control mechanism 10b.
The second pilot port of the control valve 38 is independent of the second fluid pressure chamber 20 of FIG.

Referring to FIG. 3 together with FIG.
Is gradually rotated from the neutral position around the pin 9 in the direction indicated by the arrow F, the action plate 7 moves (pushes) the push rod 12 downward. The push rod 12 pushes the receiving member 22 downward. Following this, when the spool 14 descends by a predetermined distance, the spool land 14a blocks the flow path between the second fluid pressure chamber 20 and the fluid pressure chamber 40 for the first time. When the spool land 14b descends, the pressure fluid from the pilot pressure supply source 30 starts to be supplied from the first fluid pressure chamber 18 to the second fluid pressure chamber 20, and the fluid pressure in the second fluid pressure chamber 20 decreases. To rise. This pilot secondary pressure is supplied to one pilot port of the control valve 38 via the flow path 36, and acts to switch the control valve 38 from the illustrated neutral state to the left function.

Since the diameter of the spool land 14a is formed larger than that of the spool land 14b, the force for moving the spool 14 upward is applied to the first fluid pressure chamber 18a.
This starts to occur when the pressurized fluid is supplied to the second fluid pressure chamber 20 from. As a result, the pilot secondary pressure determining coil spring 26 starts to bend. Push rod 1
2 moves relative to the spool 14 downward by a predetermined distance while flexing the coil spring 26 for determining the pilot secondary pressure. That is, the distance between the upper end of the receiving recess of the push rod 12 and the upper end of the head of the spool 14 is absorbed,
They are substantially in contact with each other. Push rod 1
The relative movement of the second spool 14 to the spool 14 determines the pilot secondary pressure.

When the relative movement distance, which is the relative movable range of the push rod 12 with respect to the spool 14, is completely absorbed, the upper end of the receiving recess of the push rod 12
The spool 14 is forcibly pushed down, and the first fluid pressure chamber 18 and the second fluid pressure chamber 20 communicate with each other in a fully opened state. This maximizes the pilot secondary pressure.

The switching of the control valve 38 is performed as described above, and the operation of an actuator (not shown) is controlled. The switching of the control valve 38 is controlled by the turning operation of the operation lever 6, but the operating force determining coil spring 24 is compressed as the push rod 12 is lowered. The operating force determining coil spring 24 is constituted by a non-linear coil spring (unequal pitch coil spring) as described above, and therefore the operating force of the operating lever 6 is controlled by the operating lever 6 as shown in FIG. 6 becomes a nonlinear change shown as a curve bulging downward with respect to the stroke L2 (see the solid line in FIG. 3). Since the gradient of the increase in the operating force in the fine operation stroke range L0 to L1 changes relatively small and smoothly, the fine operation stroke range L0
The operation force of the operation lever at L1 is reduced as compared with the related art. In FIG. 3, in the stroke L1, the operation force becomes P1-α with respect to the conventional operation force P1, the operation force is reduced by α, and the burden on the operator is reduced. Due to this, the operation feeling, particularly the operation feeling in the fine operation stroke range L0 to L1 is improved. Further, in the fine operation, even if the push rod stroke is the same as the conventional one, the operation lever stroke becomes larger, so the full stroke (L2 in FIG. 3)
In the excavation where the amount of work is often used and the fine operation is not required so much, the lever operation is heavy and matches the operator's feeling, and the operation feeling is also improved in this aspect.

As described above, there are two pilot pressure control mechanisms (10a and 10b) before and after, and two pilot pressure control mechanisms (1
0c and 10d) are provided. The two front and rear 10a and 10b of the pilot pressure control mechanism are operated and controlled by turning the operation lever 6 in the front-rear direction, and the two left and right 10c and 10d of the pilot pressure control mechanism are controlled by the left and right of the operation lever 6. The operation is controlled by turning in the direction. The operating force determining coil spring 24 may be a non-linear coil spring in all of the pilot pressure control mechanisms, or may be a part of the selected non-linear coil spring.
And two left and right 10c of the pilot pressure control mechanism
In the case where the coil spring 24 of only 10 and 10d is formed of a non-linear coil spring, the operability of the operation lever 6 in the left-right direction is particularly improved. This is because a person can exert a relatively strong force on the operation of the operation lever 6 in the front-rear direction, but feels heavy with the same force on the left-right operation. as a result,
The operation feeling in the front-rear and left-right directions of the operation lever 6 is improved in a well-balanced manner as a whole.

As described above, the embodiment of the pilot control valve according to the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the present invention. is there. For example, as the non-linear coil spring, the unequal-pitch coil spring 24 is used in the above embodiment, but the present invention is not limited to this. This can be achieved by using other non-linear coil springs, for example, a conical coil spring, a barrel coil spring, a taper coil spring, or the like. As in the embodiment, the non-uniform pitch coil spring 24 is used as the non-linear coil spring.
Is used, the outer diameter is constant over the entire length, so that the space in the outer diameter direction is constant, which is advantageous in terms of space. In the above embodiment, a pilot control valve for an operation lever is used. However, in some embodiments, a pilot control valve for an operation pedal, which is known per se, is used.

[0020]

According to the pilot control valve of the present invention, within the fine operation stroke range of the operation member,
It is possible to obtain a desired preferable operating force which is reduced as compared with the related art. As a result, the burden on the operator is reduced.
Further, the operation feeling, particularly the operation feeling in the fine operation stroke range is improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a pilot control valve configured according to the present invention.

FIG. 2 is a schematic view of FIG. 1 as viewed from above, showing a layout of an operating force determining coil spring of each of an operating lever and a pilot pressure control mechanism.

FIG. 3 is a diagram showing a relationship between a stroke of an operating lever and an operating force in the pilot control valve shown in FIG.

[Explanation of symbols]

2 Valve housing 6 Operating lever 10a, 10b, 10c, 10d Pilot pressure control mechanism 12 Push rod 14 Spool 18 First fluid pressure chamber 20 Second fluid pressure chamber 24 Coil spring for determining operating force of operating lever 30 Pilot pressure supply Source 38 control valve

Claims (3)

[Claims] An operating member provided on a valve housing and operated by an operator, and a pilot pressure control mechanism operated and controlled by the operating member, wherein the pilot pressure control mechanism is provided on the valve housing and A push rod that is pushed in conjunction with the operating member, a spring member for determining an operating force of the operating member provided between the valve housing and the push rod in the valve housing, And a spool disposed so as to be relatively movable via the pilot secondary pressure determining spring member and the operating force determining spring member of the operating member, the spool being controlled when the operating member is not operated. The pilot port of the valve communicates with the drain tank, and in operation, the pilot port communicates with the pilot pressure supply source. The pilot control valve, wherein the operating force determining spring member is formed of a non-linear coil spring. 2. The pilot control valve according to claim 1, wherein said non-linear coil spring is an unequal pitch coil spring. 3. The pilot pressure control mechanism according to claim 1, wherein the operation member comprises an operation lever that is pivotable in the front-rear direction and the left-right direction. The front and rear two of the pilot pressure control mechanisms are operated and controlled by turning the operation lever in the front and rear direction, and the left and right two of the pilot pressure control mechanisms are operated and controlled by turning the operation lever in the left and right direction. 2. The pilot control valve according to claim 1, wherein the operating force determining spring members of the two left and right pilot pressure control mechanisms are constituted by the non-linear coil springs.