JP3531981B2 - Hydraulic control valve - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control valve that controls the flow of hydraulic pressure to a hydraulic drive system, and more particularly to a hydraulic control valve that can regulate the stroke of a spool.

[0002]

2. Description of the Related Art Various hydraulic control valves have been known as a hydraulic control valve for controlling the flow of hydraulic pressure to a hydraulic drive system. Some of these hydraulic control valves are provided with a stroke restricting means for restricting the stroke of the spool in order to restrict the operating speed of the hydraulic drive system.

FIG. 6 shows an example of a hydraulic control valve provided with such a stroke regulating means. The hydraulic pressure control valve 80 is a spool valve having a spool 82. When a pilot pressure is applied to a right pressure receiving surface (not shown) of the spool 82 through a first pilot pressure port on the right side (not shown), the spool 82 moves The second pilot pressure port 8 is located on the upper left side in the figure while operating in the leftward direction.
When the pilot pressure is introduced through 4, the pilot pressure acts on the left pressure receiving surface 82a of the spool 82 via the valve passage 85 and the inner hole 83 of the stroke regulating spool 86, and the spool 82 operates rightward in the drawing. It is a thing.

In this case, the hydraulic control valve 80 can regulate the leftward stroke of the spool 82 by the stroke regulating spool 86. That is, the left pressure receiving surface 86a of the stroke regulating spool 86 is passed through the third pilot pressure port 88 located on the lower left side in the figure.
When the pilot pressure is applied to the stroke restricting spool 86 and the stroke restricting spool 86 is moved rightward in the drawing until the contact portion 87 of the stroke restricting spool 86 hits the step 90 of the valve body, the stroke restricting state is set. .

In this regulated state, pilot pressure is applied to the right pressure receiving surface (not shown) of the spool 82, and the spool 8
When 2 is moved to the left in the figure, the spool 82 moves by a predetermined stroke and then moves to the left pressure receiving surface 82a.
Hits the end of the stroke regulating spool 86 and cannot move any further, and the operating speed of the hydraulic drive device is regulated.

That is, in this structure, the spool 82 is brought into contact with the stroke regulating spool 86 before the port communicating with the hydraulic pressure supply side or the hydraulic pressure discharge side and the port communicating with the hydraulic drive unit are communicated with each other at a predetermined fully opened position. In contact with each other, the lap amount of the ports via the annular groove 92 is regulated, so that a throttle resistance is applied to the pressure oil to be pressure-fed, and the supply amount or the discharge amount of the pressure oil to the hydraulic drive device is regulated. The operating speed of the hydraulic drive device is regulated.

[0007]

By the way, at the time of so-called inching operation for finely operating the hydraulic drive unit, the lap amount between the ports is regulated so that the hydraulic drive unit and the hydraulic supply side (or the hydraulic discharge side) can be controlled. Needless to say, it is necessary to slow down the operating speed of the hydraulic drive unit by applying throttling resistance to the pressure oil that is pumped, but in order to perform the inching operation reliably and easily, the hydraulic drive unit must be It is desirable that the throttle amount of the pressure oil can be finely adjusted in the longest stroke of the operating lever to be operated, and that the throttle amount can be easily maintained to some extent. this is,
This is because the inching operation becomes very difficult when the aperture amount changes greatly even by slightly moving the operation lever.

However, generally, the stroke of the spool 82 required to come into contact with the stroke regulating spool 86 is small. Therefore, in the case of the hydraulic control valve 80 described above, the stroke of the operation lever required to bring the spool 82 into contact with the stroke regulating spool 86 is relatively short, and once the spool 82 comes into contact with the stroke regulating spool 86. , The spool 82 does not move even if the operation lever is further moved, and the spool 8 is simply moved.
The pressing force for pressing 2 only increases. That is, since the spool 82 moves with a comparatively small operating force, the spool 82 comes into contact with the stroke regulating spool 86 (reaches the regulating position) only by moving the operating lever to some extent, and the pressure oil is discharged. The aperture amount of No. reaches a predetermined aperture amount at a stretch. Therefore, the inching operation is extremely difficult to perform.

In the case of the hydraulic control valve 80 described above, the operating lever is moved by a predetermined stroke and the spool 82 is moved.
The operating speed of the hydraulic drive device is maintained at a predetermined speed in the state where the spool is abutted against the stroke restricting spool 86, but until the spool 82 is brought into contact with the stroke restricting spool 86, the pressure oil The squeezing condition has to depend only on the fine operation of the operation lever by the operator. As described above, this fine operation is extremely difficult because the stroke of the operation lever until reaching the regulation position is short.

That is, in the structure of the hydraulic control valve 80 described above, the movement of the spool 82 is restricted only after the spool 82 contacts the stroke restricting spool 86, and the stroke restricting spool 86 assists the inching operation. It is not a matter of merely restricting the movement of the spool 82 at a certain position to restrict the amount of lap between the ports. Therefore, since the action of the stroke regulating spool 86 does not work until the spool 82 comes into contact with the stroke regulating spool 86, the operator's operation technique must be used to make a slight change in the throttle amount during that period. In other words, it is difficult to maintain the amount of pressure oil throttled at an arbitrary amount.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to finely adjust the throttle amount of pressure oil in a stroke as long as possible of an operating lever for operating a hydraulic drive system. An object of the present invention is to provide a hydraulic control valve suitable for an inching operation that can hold the throttle amount to some extent easily.

[0012]

In order to achieve the above object, the present invention provides a hydraulic control valve comprising a spool actuated by pilot pressure and stroke restriction means for restricting the stroke of the spool. Until the stroke of the spool is restricted, an operating force restriction means for continuing to apply a reaction force against the operating force to the spool is provided, and the operating force restriction means is an end portion in the operating direction of the spool. It is formed as an actuating force regulating piston that abuts against and operates by receiving the same pilot pressure as that for operating the spool.

[0013]

In the above structure, the spool does not move unless a force sufficient to resist the reaction force of the operating force regulating means is generated in the spool. That is, in order to move the spool, an extra force is required to resist the reaction force of the operating force regulating means, as compared with the conventional hydraulic control valve in which the operating force regulating means is not provided. Therefore, when the same operating force (stroke of the operating lever) is applied, the moving amount of the spool becomes smaller than that of the conventional hydraulic control valve that does not have the operating force regulating means.
In other words, when the pilot pressure changes according to the operation amount of the operation lever, the reaction force of the operating force regulation means increases the force required to operate the spool as compared with the case without the operating force regulation means. Therefore, even if the spool is moved slightly, the stroke of the operation lever must be increased. Therefore, the throttle amount of the pressure oil can be finely adjusted in the long stroke of the operation lever.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4, the hydraulic control valve 1 of the present embodiment constitutes a valve unit together with a plurality of other hydraulic control valves, and is hydraulically operated to drive, for example, a boom or arm of a construction work machine such as a power shovel. It controls the supply and discharge of hydraulic pressure to the actuator 35 (piston / cylinder structure).

As shown, the hydraulic control valve 1 includes a valve body 2
And a spool 3 (hereinafter referred to as a main spool 3) having an outer diameter D slidably accommodated in the valve body 2, and ports 5 for introducing pilot pressure provided on both sides of the valve body 2.
It is composed of two port housings 4a and 4b having 6 and 7. In this case, the main spool 3 is operated by the pilot pressure introduced into the valve main body 2 through the pilot pressure introducing ports 5, 6, 7 and
The communication between the ports C ₁ , C ₂ , P, R, and R'provided in each is controlled.

Of the ports provided in the valve body 2, the port C ₁ is the rod side chamber 36 of the actuator 35.
Via hydraulic line 39, port C ₂
It communicates with the head side chamber 35 of the actuator 35 via a hydraulic line 38. The port P communicates with a pipeline connected to a pump (not shown) as a hydraulic pressure supply source (not shown), and the center bypass port R and the port R ′ are connected to a reservoir tank 33 (not shown). Is in communication with.

The first port housing 4a located on the left side of the valve body 2 is provided with a first pilot pressure introducing port 5 and a second pilot pressure introducing port 6, and the valve body is also provided. A third pilot pressure introducing port 7 is provided in the port housing 4b located on the right side of 2.

FIG. 1 shows a cross section of a main part of the hydraulic control valve 1. As shown in the figure, a spool housing chamber 25 is formed in the first port housing 4a, and the spool housing chamber 25 faces the second pilot pressure introducing port 6 and communicates therewith. Further, a pilot pressure introducing hole 8 is formed in the first port housing 4a, and the pilot pressure introducing hole 8 connects the first pilot pressure introducing port 5 and the spool accommodating chamber 25.

In the spool accommodating chamber 25, a stroke regulating spool 22 for regulating the leftward stroke of the main spool 3 and a stroke regulating spool 2 are provided.
The inching operation spool 20 that applies a resistance force to the operation of the main spool 3 is accommodated within a stroke range regulated by 2 and over substantially the entire length of the stroke.

The stroke regulating spool 22 is formed in a substantially cylindrical shape and is slidably fitted in the spool accommodating chamber 25. Further, the stroke regulating spool 22 has an annular protrusion 22 on the outer peripheral surface of the right end portion thereof.
a is formed, and the annular projection 22 a is located at the open end of the spool accommodating chamber 25, and the step 2 a of the valve body 2
By hitting against, the movement to the right is restricted. In this case, the right end surface of the stroke restricting spool 22 forms a restricting surface 43 that contacts the left end surface 40 of the main spool 3 and restricts the leftward movement of the main spool 3. Further, in the present embodiment, when the annular projection 22a is in contact with the stepped portion 2a of the valve body 2 and the main spool 3 is in the neutral position, the restriction surface 43 of the stroke restriction spool 22 and the left side of the main spool 3 are left. A gap having a distance x is formed between the end face 40 and the end face 40.

An annular groove 2 for introducing the pilot pressure introduced through the pilot pressure introducing hole 8 into the spool 22 is provided on the outer peripheral surface of the stroke regulating spool 22.
8 and a drilled hole 9 are formed.

On the other hand, the inching operation spool 20 is slidably fitted in the inner hole of the stroke regulating spool 22. This inching operation spool 20 is
An inching spool body 20a having an outer diameter of d and a flange portion 20b formed on the left end portion of the inching spool body 20a. The right end surface 44 of the flange portion 20b is formed on the inner surface of the stroke regulating spool 22. By hitting the step portion 22b, the rightward movement is restricted.

The left end surface of the flange portion 20b of the inching operation spool 20 is formed as a pressure receiving surface 42 for receiving the pilot pressure from the second pilot pressure introducing port 6. Then, in the inching operation spool 20, the pilot pressure acts on the pressure receiving surface 42 and the right end surface 44 of the flange portion 20b abuts the step portion 22b of the stroke regulating spool 22, and the right end portion of the spool body 20a. Is formed so as to project forward from the restriction surface 43 of the stroke restriction spool 22. In addition, the right end portion of the spool body 20a has the regulation surface
When the main spool 3 is in the neutral position, the distance y between the right end surface 41 of the inching spool main body 20a and the left end surface 40 of the main spool 3 in the state of protruding from 3 is large.
Gaps are formed.

An annular groove 27 is formed on the outer peripheral surface of the inching spool body 20a for introducing the pilot pressure introduced through the hole 9 of the stroke regulating spool 22 into the inner hole 10 of the inching spool body 20a. The pilot pressure is introduced into the valve body 2 from the annular groove 27 through the inner hole 10.

Next, the operation of the hydraulic control valve 1 having the above structure will be described with reference to the graphs of FIGS. 2 is a graph showing the relationship between the stroke of the operation lever 30 that controls the supply of pilot pressure to the hydraulic control valve 1 and the force acting on the main spool 3 and the inching operation spool 20. 2 is a graph in which the relationship in FIG. 2 is replaced with the relationship between the stroke of the operation lever 30 and the displacement amount of the main spool 3.

As shown in FIG. 4, when the operating lever 30 is operated in a predetermined direction, the pilot pressure corresponding to the stroke of the operating lever 30 is transmitted through the first pilot pressure line 60 to the first pilot pressure introducing port. Introduced in 5. The pilot pressure introduced into the port 5 is introduced into the valve body 2 from the port 5 through the pilot pressure introduction hole 8, the drilled hole 9 and the inner hole 10 to move the main spool 3 to the right in the figure. To move. As a result, the pressure oil pumped by the pump serving as a hydraulic pressure source flows from the port P through the annular groove 50 of the spool 3 to the port C ₁ and is sent into the rod side chamber 36 of the actuator 35 through the hydraulic line 39. To be At this time, the actuator 35
The oil in the head side chamber 37 flows from the port C ₂ to the port R ′ via the hydraulic pipe 38 and is discharged to the reservoir tank 33. Therefore, the actuator 3
5 performs contraction operation.

On the other hand, when the operating lever 30 is operated in the direction opposite to the above-described direction, the pilot pressure corresponding to the stroke of the operating lever 30 is transmitted through the second pilot pressure conduit 62 to the third pilot pressure introducing port. Introduced in 7.
The main spool 3 is moved leftward. As a result, the pressure oil pumped by the pump serving as the hydraulic pressure source flows from the port P through the annular groove 50 of the spool 3 to the port C ₂ and through the hydraulic pipe 38 the actuator 3
5 is sent into the head side chamber 37. Further, at this time, the oil in the rod side chamber 36 of the actuator 35 flows from the port C ₁ to the port R ′ via the hydraulic pipe 39 and is discharged to the reservoir tank 33. Therefore, the actuator 35 performs the extension operation.

By the way, for example, this actuator 35
When it is desired to slow down the operation speed in the extension operation of, the directional control valve 32 in two directions and two positions is electromagnetically switched by a switch (not shown). As a result, the directional control valve 32 is switched from the illustrated position where the second pilot pressure introducing port 6 is connected to the reservoir tank 33 to connect the pilot pressure introducing port 6 to the second pilot pressure conduit 62. . That is, the third pilot pressure conduit 64 connected to the port 6 is connected to the second pilot pressure conduit 62 via the directional control valve 32 and the conduit 63.

In this state, the same pilot pressure p corresponding to the stroke of the operating lever 30 is applied to both ports 6 and 7.
Will be introduced to. When the operation lever 30 is operated up to a predetermined stroke L (see FIGS. 2 and 3), the pilot pressure p introduced into the port 6 causes both the stroke regulating spool 22 and the inching operation spool 20 to move to the right position. It is moved to the center right direction and held at the stroke restriction position. That is, the stroke regulating spool 22 is brought into contact with the step portion 2a of the valve body 2, and the inching operation spool 20 is brought into contact with the step portion 22b of the stroke regulating spool 22 so as to project from the regulating surface 43 of the spool 22. To do. Further, the right end surface 41 of the inching spool body 20a and the left end surface 40 of the main spool 3 are separated by a distance y, and the restriction surface 43 of the stroke restricting spool 22 and the left end surface 40 of the main spool 3 are separated by a distance. The state is separated by x. This state is shown in FIG. 1 and (A) in FIGS. 2 and 3.

When the operation lever 30 is further moved from this state, the main spool 3 is operated by the pilot pressure F (= pπD ² /
It receives the force of 4) and moves to the left (states (a) to (b) of FIGS. 2 and 3). When the main spool 3 moves by the distance y, the left end surface 4 of the main spool 3
0 contacts the right end surface 41 of the inching spool body 20a (state of (b) of FIGS. 2 and 3). After that, the main spool 3 cannot move to the left unless the pilot pressure p sufficient to push the inching spool body 20a back to the left is introduced to the port 7. Therefore, the main spool 3 does not move even if the operation lever 30 is stroked until the force F _s capable of moving the inching spool body 20a acts on the main spool 3 (see (b) to (c) in FIG. 3). Status).

If the inching operation spool 20 is not provided, the main spool 3 operates with the operating force F (= pπD ² /
The force of 4) causes the displacement amount to increase to x in accordance with the straight line shown by the dotted line in FIG. However, in this embodiment, since the inching operation spool 20 is present, the main spool 3 is displaced according to the straight line shown by the solid line in FIG. That is, the operation lever 30 is further stroked from the state of (b) to apply a force F to the main spool 3.
_{When s} is acted (state (C) of FIGS. 2 and 3), the main spool 3 starts moving while pushing the inching spool body 20a back to the left. At this time, the main spool 3, to work in a direction opposite to the movement direction of the force f (= pπd ^2/4) is the main spool 3 which acts on the inching operation spool 20 (the right direction), the main spool 3 is actually becomes possible to move to the left in the actuation force of the force F'(= pπ (D-d ) 2/4) ( shown in dotted lines in FIG. 2). Of course, the pilot pressure p increases with the stroke of the operating lever 30.

After that, when the main spool 3 is moved by the distance x under the actuation force of F ', the left end face 40 of the main spool 3 becomes the regulating surface 4 of the stroke regulating spool 22.
3 and the main spool 3 is prevented from moving to the left. Therefore, after that, even if the operation lever 30 is stroked, the main spool 3 does not move, and simply
It only increases the force acting on the main spool 3.
The chain double-dashed line in FIG. 3 indicates the inching operation spool 2
The displacement path of the main spool 3 when there is no 0 and only the stroke regulating spool 22 is shown.

FIG. 5 is a graph showing the relationship between the stroke of the main spool 3 and the opening area of the communication passage of each port. In the figure, 1 is a stroke (opening start stroke) that the main spool 3 should move before the ports of the valve body 2 start communicating (opening) via the annular groove 50 of the main spool 3. The line P-R in the figure is a curve showing the opening area of the communication passage between the ports P and R,
The C ₁ -R 'line is a communication path between the ports C ₁ and R' (when the main spool 3 moves to the left, oil from the actuator 35 is transferred through this communication path to the reservoir tank 33).
Curve, P over C _2-wire of an aperture area of the discharge is), the
6 is a curve showing an opening area of a communication passage between the port P and the port C ₂ (when the main spool 3 moves leftward, oil from the pump is supplied to the actuator 35 through this communication passage).

As described above, in the hydraulic control valve 1 of this embodiment, once the main spool 3 comes into contact with the inching operation spool 20, the main force is the amount of pushing back the inching operation spool 20. The main spool 3 does not move unless it occurs on the spool 3. In other words, in the case of the hydraulic control valve 1 of the present embodiment, in order to move the main spool 3, the amount by which the inching operation spool 20 is pushed back in comparison with the conventional hydraulic control valve in which the inching operation spool 20 is not provided. Force (due to the area difference between the main spool 3 and the inching operation spool 20)
Is needed more. Therefore, when the same operation force (stroke of the operation lever 30) is applied, the movement amount of the main spool 3 is larger in the hydraulic control valve 1 of the present embodiment than in the conventional hydraulic control valve without the inching operation spool 20. Less is. In other words, the inching operation spool 2
Due to the reaction force of 0, the force required to operate the main spool 3 becomes larger than that when the inching operation spool 20 is not provided.
Even when moving, the stroke of the operating lever 30 must be large. This is also clear by comparing the slopes of the solid line portion (this embodiment) and the dotted line portion (conventional) in FIG. This means that the hydraulic control valve 1 of the present embodiment can finely adjust the throttle amount of the pressure oil in the long stroke of the operation lever 30, and can easily hold the throttle amount to some extent. Therefore,
Inching performance is significantly improved compared to the past.

Further, in the hydraulic control valve 1 of this embodiment, the pilot pressure p, which changes according to the operation amount of the operation lever 30, acts on both the inching operation spool 20 and the main spool 3, so that inching is performed. The force required to push back the operation spool 20 also changes according to the change in the movement amount of the main spool 3. If the change in the resistance force caused by the inching operation spool is appealed to the operation feeling of the operator who operates the operation lever 30, it is possible to intuitively recognize the throttle amount of the pressure oil, and moreover, the operation lever 30. Can be held at an arbitrary stroke position to easily hold the pressure oil at a predetermined throttle amount.

Furthermore, in the present embodiment, since the inching operation spool 20 is arranged inside the stroke regulating spool 22, the mechanism is compact and the inching performance is good, and yet the hydraulic control valve is provided. There is also an effect that 1 does not have to be upsized.

In this embodiment, the inching spool body 2 is in the state shown in FIG. 1 (the state shown in FIGS. 2 and 3B).
0a right end face 41 and main spool 3 left end face 40
Although a gap of a distance y is formed between and, this gap may be omitted. This is because the opening start stroke of the main spool 3 is 1 (see FIG. 5), and if the distance y is set to this dimension or less, there is no particular problem.

Further, in the present embodiment, in the state of FIG. 1, a gap of a distance x is formed between the regulation surface 43 of the stroke regulation spool 22 and the left end surface 40 of the main spool 3, but this distance x The larger is the operating lever 30
Since the opening area of the communication passage between the ports increases at the final stroke position, the operating speed of the actuator 35 at the final stroke position increases. In this case, it is preferable that the stroke regulating spool 22 is of a screw type so that the distance x can be adjusted arbitrarily.

[0039]

As described above, according to the hydraulic control valve of the present invention, the throttle amount of the pressure oil can be finely adjusted in the longest possible stroke of the operating lever for operating the hydraulic drive device, and the throttle amount can be adjusted. It can be held to some extent easily.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts of a hydraulic control valve according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the stroke of an operating lever that controls the supply of pilot pressure to a hydraulic control valve and the force acting on a main spool and an inching operation spool.

FIG. 3 is a graph diagram in which the relationship of FF ′ in FIG. 2 is replaced with the relationship between the stroke of the operation lever and the displacement amount of the main spool.

4 is a cross-sectional view of a main part of a valve unit having the hydraulic control valve of FIG.

FIG. 5 is a graph showing the relationship between the stroke of the main spool and the opening area of the communication passage of each port.

FIG. 6 is a sectional view of a main part of a conventional hydraulic control valve.

[Explanation of symbols]

1 ... Hydraulic control valve, 3 ... Main spool (spool), 2
0 ... Inching operation spool (operating force regulating means), 2
2 ... Stroke restriction spool (stroke restriction means).

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-64785 (JP, A) Actually opened 62-25302 (JP, U) Actually opened 63-45273 (JP, U) Actually opened 63- 115678 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16K 11/07 F16K 31/12-31/165 F16K 31/36-31/42 F15B 11/08

Claims (4)

(57) [Claims] 1. A hydraulic control valve comprising a spool actuated by pilot pressure and a stroke restriction means for restricting the stroke of the spool, wherein the spool is controlled until the stroke of the spool is restricted. An operating force regulating means for continuously applying a reaction force against the operating force is provided, and the operating force regulating means is in contact with an end portion in the operating direction of the spool and has the same pilot pressure as the pilot pressure for operating the spool. A hydraulic control valve, which is formed as an actuation force regulating piston that receives and operates. 2. The spool is operated by an operating force generated by a difference between an area of a receiving portion of the operating force regulating piston receiving pilot pressure and an area of a pressure receiving portion of the spool receiving pilot pressure. The hydraulic control valve according to item 1. 3. The hydraulic control valve according to claim 1, wherein the actuating force regulating means is provided integrally with the stroke regulating means. 4. The hydraulic control valve according to claim 3, wherein the actuating force regulating means is slidably fitted in the stroke regulating means.