JP3593334B2 - Control valve - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control valve for controlling a hydraulic actuator used for a construction machine or an industrial machine.
[0002]
[Prior art]
Construction machines such as hydraulic excavators have hydraulic actuators such as hydraulic cylinders. The hydraulic actuator is controlled by a control valve. The control valve has a spool, and controls the operation of the actuator by switching the direction and flow rate of hydraulic oil by moving the spool.
[0003]
FIG. 5 is a sectional view showing a part of the conventional control valve 1. The control valve 1 has a main body 2 and a spool 3 movably inserted into the main body 2. A pilot chamber 4 is provided at an end of the spool 3. This pilot chamber 4 is provided with a spring 6 for returning to neutral. The pilot chamber 4 is connected via a pilot line 5 to a pilot valve (not shown) operated by an operator. At the opposite end of the control valve 1, a similar pilot chamber 4 'and a spring 6' are provided (neither is shown).
[0004]
When the operator operates the pilot valve to supply pressure oil to the pilot chamber 4, the spool 3 moves to one side (to the left in FIG. 5) against the spring force of the spring 6 'and, for example, the hydraulic cylinder extends. I do. Conversely, when the pilot chamber 4 communicates with the drain and pressurized oil is supplied to the pilot chamber 4 ′, the spool 3 moves to the other side (to the right in FIG. 5) against the spring force of the spring 6 and the hydraulic cylinder Contracts. Thus, a hydraulic actuator such as a hydraulic cylinder can be controlled.
[0005]
The control valve 1 is attached to a machine body such as a hydraulic shovel, for example. At the stage where the control valve 1 is attached and piped, the pilot chambers 4 and 4 'contain air, so it is necessary to release air.
[0006]
It is necessary to perform such air bleeding not only when the control valve is attached but also when air enters the pilot chamber due to oil leakage or the like when the operation is stopped for a long time.
[0007]
A drain passage 7 communicating with the tank is formed in the main body 2 of the control valve 1, and a recess 8 is formed at an end of the spool 3. The pressure oil is supplied to the pilot chamber 4 ′ to move the spool 3 to the other side (to the right in FIG. 5), and the recess 8 allows the pilot chamber 4 to communicate with the drain passage 7. The air is discharged from the drain passage 7 and air is removed. As a prior art of such a control valve using a spool having a recess, there is, for example, Japanese Patent Publication No. 5-31037.
[0008]
[Problems to be solved by the invention]
In the structure shown in FIG. 5, the air release is performed in a state in which the pressure oil is supplied to the pilot chamber on the side where the air is not released, and the pressure oil is not supplied to the pilot chamber on the side where the air is released. That is, since the air is bleeding in a state where the pilot chamber is at the atmospheric pressure, there is a problem that the air bleeding effect is small as compared with a case where the pressure oil is supplied to bleed the air.
[0009]
Further, as another conventional technique, there has been a method of providing communication by providing an orifice or a gap between the pilot chamber and the drain chamber. However, in this method, even when it is no longer necessary to bleed air, the pilot chamber is not required. When the pressurized oil is supplied to the pump, the above-mentioned passage is always communicated, and the pressurized oil flows out of the pilot chamber, which results in energy consumption and a decrease in the pilot chamber pressure in some cases.
[0010]
It is an object of the present invention to perform air bleeding by connecting the drain and the pilot chamber only when necessary, to accurately reproduce the original maximum stroke after air bleeding, and to increase the air bleeding effect more than before. It is to provide a control valve which can be used.
[0011]
[Means for Solving the Problems]
The present invention relates to a control valve having a main body and a spool movably inserted into the main body, wherein the control valve moves the spool in the axial direction by the pressure of the pilot chambers 20 , 25 facing the spool ends 12a, 12b .
Opposite the either end of the spool attached to said main body, a cover 13, 14 has an inner thread may be formed,
A stopper 30,30A that attached to the cover, wherein the stopper is externally screw formed to be screwed into the inner thread of the cover, the stopper by causing screwing and unscrewing, the axial direction of the spool along the stopper advancing in the direction approaching the spool end and retractable moves away from the spool end, which is engaged with the cover when brought into the forward to a predetermined position, it is positioned with respect to the cover 30 , 30A ,
Provided in the stopper to define the maximum stroke of the spool, it possesses an adjustable stroke regulating means the maximum stroke,
A drain passage 46, 46A is formed in the main body,
When the stopper is retracted and the spool is moved beyond the maximum stroke, communication portions 47 and 47A for communicating the pilot chambers 20 and 25 with the drain passages 46 and 46A are formed in the spool. Control valve.
[0012]
Further, the present invention is characterized in that the stopper has projections 37, 37A which are locked to the cover at the predetermined position and positioned with respect to the cover when the stopper is advanced .
[0013]
Further, in the present invention, the stroke defining means may include:
Stopper members 45 and 45A movable in a direction approaching and moving away from the spool end, and abutting on the spool ends 12a and 12b to define a maximum stroke of the spool;
A threaded portion 32,32A which is screwed to the scan stopper 30,30A,
Is screwed to the root Ji part, it has a nut and 33,33A to secure the threaded portion to the stopper,
The outer screw of the stopper projects in a direction (left and right in FIGS. 1 to 4 described later) farther from the spool end than the cover,
It is characterized in that lock nuts 38, 38A are provided which are screwed to the protruding outer screw portions and abut against the cover .
[0015]
According to the present invention, the stroke defining means is attached to a stopper screwed to a cover attached to the main body. The stopper is locked at a predetermined position and positioned with respect to the main body. The stroke defining means is adjustable so that the maximum stroke is adjusted at the factory before shipment.
[0016]
When bleeding air, instead of loosening the bolt of the stroke defining means, the stopper is loosened and retracted so that the spool can move beyond the maximum stroke. Then, the spool is moved until the pilot chamber communicates with the drain passage, and the pressure oil is sent to the pilot chamber, whereby the air in the pilot chamber can be discharged from the drain passage together with the pressure oil.
[0017]
After releasing the air, tighten the stopper again. At this time, the stopper can be easily returned to the original position by tightening until the stopper is locked. Since the position of the stroke defining means has not been changed, an accurate maximum stroke is reproduced by returning the stopper to the original position.
[0018]
As described above, unlike the related art described with reference to FIG. 5, the present invention supplies pressure oil to the pilot chamber on the air bleeding side to bleed air. Can be.
[0019]
In addition, since air is released by moving the spool beyond the maximum stroke, during normal use without air release, the pilot chamber and the drain do not communicate with each other. No pressure drop in the chamber.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a sectional view showing a configuration of a control valve 10 according to one embodiment of the present invention. The control valve 10 controls an actuator such as a hydraulic cylinder used in a construction machine such as a hydraulic shovel or a wheel loader, or a general industrial machine.
[0021]
The control valve 10 includes a valve casing 11 having a spool hole 15, a spool 12 movably inserted into the spool hole 15, a spool cover 13 for closing one of the spool holes 15 (the left side in FIG. 1), and a spool hole. 15 has a spring cover 14 which closes the other opening and has a spring 16. Of these, the valve casing 11, the spool cover 13, and the spring cover 14 are the main body of the control valve 10.
[0022]
The spool 12 is provided movably along the axis L in the spool hole 15. One end 12a is disposed so as to protrude from one wall surface 11a of the valve casing 11, and the other end 12b protrudes from the other wall surface 11b of the valve casing 11 to close the opening of the spool hole 15. I have.
[0023]
The spring cover 14 is fixed to the other side (the right side in FIG. 1) of the valve casing 11 by bolts. The spring cover 14 has a recess, and is fixed to the valve casing 11 so as to cover the other end 12b of the spool 12 with the recess. A pilot port 21 communicating with the recess is formed in the spring cover 14, and the recess functions as a pilot chamber 20. A bolt 22 is fixed to the other end 12 b of the spool 12. A spring receiver 23 is mounted on the head of the bolt 22, and the spring 16 is received by the spring receiver 23 and the recess of the spring cover 14. . The oil pressure in the pilot chamber 20 becomes a force for moving the spool 12 to one side (to the left in FIG. 1), and the spring 16 exerts a spring force in a direction to return the spool 12 to the neutral position when the spool 12 moves. .
[0024]
The spool cover 13 is fixed to one side (the left side in FIG. 1) of the valve casing 11 by bolts. A recess 25 is also formed in the spool cover 13, and the spool cover 13 is fixed such that the recess 25 covers one end 12 a of the spool 12. A pilot port 26 communicating with the recess 25 is formed in the spool cover 13, and the recess 25 functions as a pilot chamber 25.
[0025]
The control valve 10 is connected to actuators such as a hydraulic pump, a tank, and a hydraulic cylinder by a hydraulic line, and switches the direction of hydraulic oil to the actuator by moving the spool 12. For example, when the spool 12 is in the neutral position, the communication between the hydraulic cylinder, the pump and the tank is interrupted and the hydraulic cylinder is stopped, and the spool 12 is moved to one side (left side in FIG. 1). Then, the one end of the hydraulic cylinder communicates with the hydraulic pump, the other end of the hydraulic cylinder communicates with the tank, and hydraulic oil is supplied from one side of the hydraulic cylinder to extend the hydraulic cylinder. Conversely, when the spool 12 is moved to the other side (to the right in FIG. 1), one end of the hydraulic cylinder communicates with the tank, and the other end of the hydraulic cylinder communicates with the hydraulic pump, so that the hydraulic cylinder contracts.
[0026]
Such movement control of the spool 12 is performed by a pilot valve that controls the pilot pressure of the pilot chambers 20 and 25. The pilot valve is a valve operated by the operator, and the actuator can be remotely controlled by operating the pilot valve.
[0027]
The pilot valve is connected to the pilot pressure pump and the tank. When the operator operates the pilot valve on one side, the pilot chamber 20 communicates with the pilot pressure pump, and the pilot chamber 25 communicates with the tank. The pressure in the pilot chamber 20 increases, and the spool 12 moves to one side against the spring force of the spring 16. Thereby, one of the pump port and the cylinder port of the control valve 10 communicates, and the hydraulic cylinder extends. When the pilot valve is operated to the other side, the pressure in the pilot chamber 25 increases, and the spool 12 moves to the other side against the spring force of the spring 16. As a result, the pump port of the control valve communicates with the other of the cylinder ports, and the hydraulic cylinder contracts.
[0028]
A through hole 29 is formed in the spool cover 13, and a stopper 30 is screwed into the through hole 29. The through hole 29 is formed with the axis L of the spool 12 as a central axis, and has a step. That is, the inside (right side in FIG. 1) hole has a small diameter, and the outside (left side in FIG. 1) hole has a large diameter, and a step 34 is formed in the connecting portion. An inner screw is formed in a hole outside the through hole 29.
[0029]
The stopper 30 is attached to the through-hole 29, and the inside (right side in FIG. 1) becomes a small-diameter portion 35 that fits into the small-diameter side of the through-hole 29, and the outside becomes a large-diameter portion 36. An outer screw is formed and screwed to the inner screw of the through hole 29. An annular projecting portion 37 projecting outward in the radial direction is formed at a connecting portion between the small diameter portion 35 and the large diameter portion 36. Therefore, when the stopper 30 is screwed onto the spool cover 13, tightened and advanced, the protrusion 37 is locked by the step 34 of the through hole 29. In this way, the stopper 30 can be positioned at a predetermined position with respect to the main body only by tightening.
[0030]
A lock nut 38 is screwed around the outer periphery of the stopper 30. After the stopper 30 is positioned, the stopper 30 is prevented from loosening by tightening until the lock nut 38 comes into contact with the spool cover 13, and the stopper 30 can be securely fixed. That is, the external thread formed on the large-diameter portion 36 of the stopper 30 projects in a direction (leftward in FIGS. 1 and 2) away from the spool end 12 a with respect to the cover 13. , A lock nut 38 is screwed and comes into contact with the cover 13.
[0031]
The stroke defining means 31 is attached to the stopper 30. The stroke defining means 31 defines a maximum stroke of the spool 12, and includes a stop member 45 having a screw portion 32 and a nut 33. In the stopper 30, a through hole 40 is formed on the axis L of the spool 12, and the inside of the through hole 40 (the right side in FIG. 1) has a large diameter. (Left) becomes a small diameter, an inner screw is formed here, and the screw portion 32 is screwed. The stop member 45 has a stepped portion 45 a adjacent to the screw portion 32, and the other end surface 45 b is arranged to face one end surface of the spool 12. By rotating the screw portion 32, the screw portion 32 moves along the axis L of the spool 12, and the position of the stop member 45 can be adjusted. By tightening the nut 33 until it comes into contact with the stopper 30, the position of the screw portion 32 can be fixed.
[0032]
The maximum stroke is usually adjusted at the factory. FIG. 2 is a sectional view showing the control valve 10 after the adjustment of the maximum stroke.
[0033]
The adjustment of the maximum stroke is performed in a state where the stopper 30 is positioned at a predetermined position, that is, in a state where the protrusion 37 is locked and fixed to the step 34. The screw member 32 is rotated and advanced, and the stop member 45 is pushed out to the maximum stroke position to determine the maximum stroke. Finally, the nut 33 is tightened to fix the stop member 45.
[0034]
FIG. 3 is a diagram showing a state of the spool 12 at the time of the maximum stroke. The spool 12 can move to one side until it comes into contact with the end face 45b of the stop member 45, and is prevented from moving further to one side. The position where the stop member 45 abuts is the maximum stroke toward one side of the spool 12.
[0035]
After shipment from the factory, the control valve 10 is attached to a machine body such as a hydraulic shovel, and after piping, hydraulic oil is charged. At this time, since air is contained in the pilot chamber 20, it is necessary to release air from the pilot chamber 20.
[0036]
FIG. 4 is a diagram showing a state of air bleeding. At the other end (right side in FIG. 4) of the valve casing 11, a drain passage 46 communicating with the tank is formed. The drain passage 46 is formed at a position close to the opening on the other side of the spool hole 15. The air release is performed by communicating the pilot chamber 20 with the drain passage 46 and discharging the air in the pilot chamber 20 through the drain passage 46 together with the pressure oil guided to the pilot chamber.
[0037]
The other end 12b of the spool 12 is formed with a communicating portion 47 cut into a small diameter over the entire circumference. As shown in FIG. 3, after adjusting the maximum stroke, even if the maximum stroke is made to one side, the communication portion 47 does not reach the drain passage 46, and the large diameter portion of the spool 12 closes the opening of the spool hole 15. As a result, the pilot chamber 20 and the drain passage 46 do not communicate with each other. That is, in this state, air cannot be removed.
[0038]
Therefore, when bleeding air, the maximum stroke of the spool 12 is extended by retracting the stopper 30. That is, the lock nut 38 is loosened to loosen the stopper 30, and the stopper 30 is moved in a direction away from the one end 12a of the spool 12, so that the protrusion 37 of the stopper 30 is separated from the step 34 as shown in FIG. . At this time, the nut 33 of the stroke defining means 31 is not loosened. In this state, if the spool 12 is moved to one side, it can move beyond the maximum stroke. When the spool 12 is moved beyond the maximum stroke in this way, as shown in FIG. 4, the communicating portion 47 formed at the other end 12b of the spool 12 moves to the drain passage 46, and the pilot chamber 20 moves. And the drain passage 46 communicate with each other.
[0039]
In this state, pressure oil of about 3 to 4 MPa is supplied to the pilot chamber 20. Then, the air in the pilot chamber 20 is discharged from the drain passage 46 together with the hydraulic oil. In this manner, air is removed.
[0040]
After the air release, the stopper 30 is tightened until the protrusion 37 is locked by the step 34, and the lock nut 38 is tightened to fix the stopper 30. As a result, the original maximum stroke is accurately reproduced.
[0041]
Such air bleeding can be applied not only when the control valve 10 is attached to the machine main body, but also when the air enters the pilot chamber 20 due to oil leakage due to long-term use.
[0042]
Such a stopper 30 is not limited to the structure provided on the spool cover 13 provided on one side, and may be provided on the spring cover 14 provided on the other side. The control valve 10 shown in FIGS. 1 to 4 has a structure in which a stopper 30 </ b> A similar to the stopper 30 is provided on the spring cover 14. Since the stopper 30A and its related structure are the same as those of the stopper 30, the corresponding components are denoted by the same reference numerals with the suffix A, and detailed description is omitted.
[0043]
Such a stopper 30A of the other spring cover 14 is used when bleeding air from the pilot chamber 25 on the one spring cover 13 side. That is, at the time of bleeding air, the spool 12 is moved to the other side beyond the maximum stroke while the stopper 30A is retracted (to the right in the drawing) by the stroke defining means 31A. The air is vented by communicating the pilot chamber 25 with the drain passage 46A by the communicating portion 47A. After the air bleeding, the stopper 30A is moved forward until the protrusion 37A is locked by the step 34A and positioned at a predetermined position, whereby the original maximum stroke can be accurately returned.
[0044]
【The invention's effect】
As described above, according to the present invention, since the stopper that can be accurately positioned at the predetermined position is provided, even if the air is released after adjusting the maximum stroke of the spool, the original maximum stroke can be reproduced easily and easily. can do.
[0045]
Also, during normal use, the pilot chamber and the drain passage are not communicated with each other, and the spool is moved beyond the maximum stroke only when air is evacuated, so that the pilot chamber and the drain passage are communicated with each other to bleed air. Therefore, after the air release, the pressure in the pilot chamber does not decrease, and there is no need to make the communication portion a minute clearance, a sufficient clearance can be secured, and the air release can be reliably performed.
[0046]
Further, even when the maximum strokes are different, the maximum stroke can be easily adjusted by the stroke defining means, and common components can be used for the spool and the stopper, thereby reducing costs.
[0047]
Further, in the present invention, since the air is vented by supplying the pressure oil to the pilot chamber on the air vent side, the air venting effect is increased as compared with the prior art in which the pilot chamber on the air vent side is set to the atmospheric pressure. be able to.
Further, according to the present invention, the protrusions 37, 37A are formed on the stoppers 30, 30A, and therefore, the stoppers 30, 30A can be positioned with respect to the cover 13, and thus the main body, only by tightening the stoppers 30, 30A.
According to the present invention, the positions of the stop members 45 and 45A are adjusted by rotating the screw portions 32 and 32A of the stroke defining means 31 and 31A, and the nuts 33 and 33A are tightened. The position can be fixed. Further, lock nuts 38 and 38A are applied to the covers 13 and 14 at the portions of the external threads protruding in the direction (left and right in FIGS. 1 to 4) farther from the spool end than the covers 13 and 14 of the stopper. The screw is screwed until it comes into contact, whereby the original maximum stroke is accurately reproduced after the end of the air bleeding described above.
[Brief description of the drawings]
FIG. 1 is a sectional view of a control valve 10 before a stroke adjustment.
FIG. 2 is a cross-sectional view of the control valve 10 when a spool 12 is at a neutral position after stroke adjustment.
FIG. 3 is a sectional view of the control valve 10 during a maximum stroke.
FIG. 4 is a cross-sectional view of the control valve 10 when bleeding air.
FIG. 5 is a sectional view showing a part of a conventional control valve.
[Explanation of symbols]
Reference Signs List 10 control valve 11 valve casing 12 spool 13 spool cover 14 spring cover 30 stopper 31 stroke defining means

Claims (3)

A control valve having a main body and a spool movably inserted into the main body, wherein the control valve moves the spool in an axial direction by a pressure of a pilot chamber facing an end of the spool.
Opposite the either end of the spool attached to said body, and a cover inner thread may be formed,
A stopper that is attached to the cover, wherein the stopper is externally screw formed to be screwed into the inner thread of the cover, the stopper by causing screwing and unscrewing, along the axial direction of the spool advancing toward the spool end, and the direction to be moved backward away from the spool end, is engaged with the cover when brought into the forward to a predetermined position, the stopper is positioned with respect to the cover,
Provided in the stopper to define the maximum stroke of the spool, it possesses an adjustable stroke regulating means the maximum stroke,
A drain passage is formed in the main body,
A control valve , wherein when the stopper is retracted and the spool is moved beyond a maximum stroke, a communication portion for communicating the pilot chamber with the drain passage is formed in the spool . 2. The control valve according to claim 1 , wherein the stopper has a protruding portion that is locked to the cover at the predetermined position and positioned with respect to the cover when the stopper is advanced . The stroke defining means,
A stopper member movable in a direction approaching and moving away from the spool end, and abutting on the spool end to define a maximum stroke of the spool;
A threaded portion which is screwed to the scan stopper,
Is screwed to the root Ji part, have a nut that secures the threaded portion with respect to the stopper,
The outer screw of the stopper projects in a direction away from the spool end than the cover,
3. The control valve according to claim 1, further comprising a lock nut which is screwed to the protruding portion of the external thread and abuts on the cover .

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