JP3217469B2 - Solenoid switching valve for hydraulic - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct-acting two-position type in which a valve body slidably accommodated in a valve hole is switched by a solenoid from a normal position biased by a spring to an operating position. The present invention relates to a hydraulic electromagnetic switching valve.

[0002]

2. Description of the Related Art An electromagnetic switching valve of this type is used as a pilot valve in a pilot-operated hydraulic valve or independently used for operating an actuator. May occur. That is, the sliding portion between the valve hole and the valve element has only a small gap to maintain oil tightness, but leakage of hydraulic oil through this gap cannot be avoided. This leakage causes pressure to occur on the outer periphery of the valve element sliding portion. However, the pressure distribution is not always symmetrical. For example, a minute foreign matter may enter the gap where the leakage occurs, or the valve may be displaced by a slight processing error. The state of the leakage flow changes in the circumferential direction due to the uneven shape of the outer periphery of the body sliding part, and therefore, different pressures are distributed in the outer circumference of the valve sliding part in the circumferential direction. As a result, the valve element receiving the action of the pressure is pressed in the radial direction, and directly contacts the inner periphery of the valve hole without passing through the oil film, so that the valve element does not move with the operating force of the solenoid.

[0003] Such a sticking phenomenon of the valve body is also known as a dust lock or a hydraulic lock and is well known to those skilled in the art. Even if the sticking phenomenon of the valve body occurs, if the valve body is moved by the operating force of the solenoid against the frictional force, the sticking phenomenon can be eliminated. In the switching valve, a solenoid capable of emitting an operating force sufficient to sufficiently eliminate the sticking phenomenon of the valve body is generally used to eliminate the sticking phenomenon.

[0004]

However, when developing a small solenoid-operated directional control valve, the present inventors increased the operating force required when the solenoid was required to have a small shape so that the sticking phenomenon could be sufficiently eliminated as described above. since not, by sticking phenomenon of the valve body, a situation which can not be moved to the valve body to the operating position by the operation force of the solenoid is faced to frequent. In view of the above problems, the present invention provides a hydraulic electromagnetic switching valve capable of satisfactorily eliminating the sticking phenomenon of the valve body without directly depending on the operating force of the solenoid when switching the valve body to the operating position. It is what we are trying to realize.

[0005]

For this reason, the hydraulic solenoid-operated directional control valve of the present invention is slidably received in the valve hole of the main body, and is pressed to the normal position by the pressing force of the spring toward one end of the valve hole. A hydraulic solenoid switch having a valve body which is pushed to the other end side of the valve hole against the pressing force of the spring toward the operating position by an operating force of a solenoid provided on the main body at one end side of the valve hole. An end chamber for receiving hydraulic oil leaking through a sliding portion between the valve body and the valve hole is formed at both ends of the valve body in the valve hole, and the other end of the valve hole among the two end chambers. A discharge passage communicating the side end chamber to the tank side is provided in the main body, and a through hole communicating the one end side end chamber of the valve hole to the other end side chamber is provided in the valve body through the axial direction, The supply passage communicating with the hydraulic pressure source communicated with the valve hole at locations axially separated from each other, and the supply passage is disconnected according to the movement of the valve element. A supply passage is provided in the main body so that the supply passage communicates with the valve hole at a position where one end side of the valve hole is closer to the output passage than the output passage, and abuts against the valve body so as to press the valve body to the normal position by a spring pressing force. A spring receiving body and a pressing body that comes into contact with the valve body so as to press the valve body to the operating position by operating force of the solenoid are installed, and the pressing body is in contact with the valve body through both ends through the through hole of the valve body. It is provided with a blocking portion for blocking communication between the chambers, and is capable of contacting the spring receiver so as to release the contact of the spring receiver with the valve prior to contact with the valve.

[0006]

According to this configuration, if the valve element at the normal position does not exhibit the sticking phenomenon, the valve element is pressed and moved to the operating position by receiving the operating force of the solenoid through the contacting pressing element. If the valve element at the normal position exhibits a sticking phenomenon, even if the valve element cannot be moved only by applying the operating force of the solenoid via the pressing element, the through hole of the valve element is blocked by the contact of the pressing element. As a result, hydraulic oil from the supply passage leaking into the end chamber on one end side of the valve hole via the sliding portion between the valve body and the valve hole is blocked by blocking the discharge path to the tank side. , And the force based on the action of the increased pressure acts on the valve body in addition to the solenoid operating force, so that the sticking phenomenon is eliminated and the valve body is moved to the operating position. At this time, if the movement of the valve element is started, the volume of the end chamber on one end side of the valve hole increases, so that the pressure drops, and the force effective to press the valve element to the operating position by the pressure quickly disappears. However, once the movement is started, the sticking phenomenon is eliminated, and the valve body can be smoothly moved to the operating position by the operating force of the solenoid.

Since the elimination of the sticking phenomenon when the valve body is moved to the operating position is performed without directly depending on the operating force of the solenoid, the operating force of the solenoid is large enough to eliminate the sticking phenomenon. Even without this, the sticking phenomenon is satisfactorily eliminated.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a main body, which is provided with a sleeve 4 forming a valve hole 3 for slidably housing the valve body 2 fitted in the installation hole 5, and a solenoid 6 is screwed into an opening end of the installation hole 5. The sleeve 4 is prevented from falling out. In the main body 1, P and R denote a supply path and a discharge path, respectively, which are connected to a hydraulic source (not shown) and a tank, and A denotes an output path. In the present embodiment, the main body 1 constitutes a mounting base on which a pilot-operated switching valve V is installed at the upper part, and the output passage A communicates with the switching valve V for pilot-operating the switching valve V. ing.

The supply passage P and the output passage A are separated from each other in the axial direction with the supply passage P being on the solenoid 6 side, and penetrate the sleeve 4 in the radial direction to communicate with the valve hole 3. Also, the discharge passage R
Are end chambers 7 formed at both ends of the valve body 2 in the valve hole 3,
The end 8 communicates with the end chamber 7 on the opposite side of the solenoid 6. The valve body 2 has a circumferential groove 2A communicating with the supply passage P at the center.
And lands 2B, 2C on both sides thereof, and the lands 2B, 2C are slidably fitted to the inner periphery of the valve hole 3.
And the land 2C is connected to the output passage A.
In the illustrated normal position of the valve body 2, the valve body 2 communicates with the discharge passage R via the end chamber 7 and is cut off from the supply passage P. The switching control is performed so as to communicate with the supply passage P and cut off from the end chamber 7, that is, the discharge passage R.

Reference numeral 9 denotes a through-hole formed through the valve body 2 in the axial direction.
A step 9A with which 0A comes into contact is formed, and a step 9B with which the pressing body 11 which transmits the operating force of the solenoid 6 by expanding the diameter of the end chamber 8 side comes into contact. The spring receiving body 10 presses the valve body 2 toward the solenoid 6 in the valve hole 3 by pressing the flange portion 10A against the step portion 9A by the pressing force of the spring 12 so as to maintain the valve body 2 at the illustrated normal position. When the flange 10A is in contact with the step 9A, the tip is the step 9
B is slightly projected to the end chamber 8 side beyond B.
10B is a passage hole provided in the spring receiving body 10 so as not to hinder the flow from the end chamber 8 to the end chamber 9 through the through hole 9.

The solenoid 6 has a cylindrical portion 14 connected to a fixed iron core 13 having a screw portion 13A for screwing to the main body 1, and a movable iron core sucked by the fixed iron core 13 in the cylindrical portion 14. This is a so-called oil immersion type housing 15. Then, in order to output the suction force to the movable iron core 15 as the operation force,
The distal end of the pressing body 11 inserted into the through hole 13B of the fixed iron core 13 can be brought into contact with the movable iron core 15.
Due to the radial gap between 3B and the pressing body 11, the inside of the cylindrical portion 14 communicates with the end chamber 8 so that hydraulic oil flows from the end chamber 8. The coil 16 and the yoke 17 are provided in the cylindrical body 14.
The coil block body 18 incorporating the
9 holds this.

The diameter of the pressing body 11 is enlarged such that the front end of the valve body 2 which can be brought into contact with the front end of the spring receiving body 10 comes into contact with the step 9B in the through hole 9 of the valve body 2. The end chambers 7, 8 through the through holes 9 by contact with the valve body 2 by the enlarged diameter portion.
An interrupting portion 11A for interrupting communication between them is formed.

Next, the operation of this embodiment will be described. When the coil 16 of the solenoid 6 is de-energized, the valve 2
2 is maintained at the normal position shown in FIG.
It is assumed that the valve body 2 is in a fixed state due to minute foreign matter entering the gap between B or 2C and the inner circumference of the valve hole 3. At this time, the output passage A is isolated from the supply passage P by the land 2C, communicates with the end chamber 8, and communicates with the discharge passage R. Here, when the coil 16 is energized to move the valve body 2 to the operating position, the movable core 15 is absorbed by the fixed core and moves leftward, and is pressed against the movable core 15 to receive this attraction force. 11 abuts against the spring receiving body 10 and moves it to the left against the pressing force of the spring 12. As a result, the contact of the flange portion 10A of the spring receiving body 10 with the step portion 9A of the valve body 2 is released, and thereafter the pressing body 11A is released.
Of the valve body 2 abuts on the step 8 of the valve body 2, and the suction force acts on the valve body 2.

[0014] The valve body 2 is in a fixed state, and the suction force
Cannot be moved to the operating position only by applying
The end chamber 8 through the through hole 9 is formed by the contact of the step 1A with the step 9B.
From the end chamber 7 is shut off. On the other hand, Land 2B
Through the gap with the inner circumference of the valve hole 3 to reach the circumferential groove 2A of the valve body 2
Hydraulic oil continues to leak from the supply passage P
Therefore, the hydraulic oil in the end chamber 8 is discharged to the discharge passage R.
The pressure rises due to the blockage of the outlet. On this
The rising pressure in the end chamber 8 acts on the valve body 2, and the valve body 2
In order to apply a pressing force toward the operating position, the valve body 2 is fixed.
The movement to the operating position is canceled after the seizure phenomenon is eliminated.

Here, when the movement is started, the pressure generated in the end chamber 8 is rapidly reduced due to the increase in the volume of the end chamber 8, and the valve body 2 is pressed to the operating position based on this pressure. Although the effective force rapidly disappears, it has been confirmed by experiments by the present inventors that the sticking phenomenon of the valve body 2 is eliminated once the movement starts, and the movable iron core 15 is fixed to the fixed iron core 13.
The pressing body 11 moves the valve body 2 to the left together with the spring receiving body 10 until the valve body 2 reaches the operating position until the lands 2C discharge the output passage A through the end chamber 7. The communication with the passage R is interrupted, and the communication with the supply passage P is made via the circumferential groove 2A.

Thereafter, if the pressure inside the end chamber 8 rises due to the accumulation of the leaking hydraulic oil from the supply passage P through the outer periphery of the land 9B, the valve element 2 causes the spring receiving body 1 to move again by the action of this pressure.
The flange 10A moves slightly to the left so as to contact the step 9A of the valve body 2, and the contact of the pressing body with the step 9B by the blocking part 11A is released. 9, the interior of the end chamber 8 is drained through the through hole 9 to the end chamber 7 and the discharge passage R. When the valve body 2 is in the operating position, the end chamber 8 is closed. The inside is not kept in a boosted state.

When the coil 16 of the solenoid 6 is de-energized, the spring receiving body 10 moves rightward through the movable iron core 15 via the pressing body 11 in the contact state by the pressing force of the spring 12, and The valve body 2 is moved rightward by bringing the flange portion 10A into contact with the step portion 9A, and is moved to the illustrated normal position. At this time, as described above, in the operating position of the valve body 2, the end chamber 8 is not drained and maintained in a pressurized state, and the hydraulic oil in the end chamber 8 passes through the through hole when the valve body 2 moves to the right. The valve body 2 can be moved by the pressing force of the spring 12 without being blocked by the pressure of the end chamber 8 because it can flow through the end chamber 7 through the end chamber 9.

In the operating position of the valve element 2, the valve element 2
However, when the valve body 2 is moved to the normal position, there is no opposing force such as the pressing force of the spring 12 that is present when the valve body 2 is moved from the normal position to the operating position. In addition, since the spring 12 is in a state in which the spring 12 receives a compressive deformation and emits a larger pressing force than in the normal position of the valve body 2, the sticking phenomenon is eliminated by the pressing force of the spring 12, and the valve body 2 moves. Is completed without any problems.

If the valve body 2 does not exhibit the sticking phenomenon at the normal position, the interrupting portion 11A of the pressing body 11 causes the valve body 2 to be pulled by the suction force of the solenoid 6 without waiting for the pressure in the end chamber 8 to rise. And the valve body 2 is moved to the operating position.

Generally, the movable iron core 15 of the solenoid 6
Assuming that the current to the coil 16 is constant, the larger the distance between the fixed iron core 13 and the movable iron core 15 is, the smaller the attraction force becomes. If it is necessary to move the solenoid 6 against the pressing force of the spring 12 by force, and if the size of the solenoid 6 cannot be increased in order to obtain a small solenoid-operated directional control valve, the suction force enough to eliminate the sticking phenomenon of the valve body 2 However, according to this embodiment, the pressure in the end chamber 8 is increased without directly depending on the suction force to eliminate the sticking phenomenon, and the pressing force due to this pressure is added to the suction force. As a result, the small solenoid 6 having a small suction force can be used without any trouble, and an optimal small electromagnetic switching valve according to the specifications can be obtained. Further, since the hydraulic oil leaking from the outer periphery of the land 2B of the valve body 2 from the supply passage P is used for pressure generation in the end chamber 8 for eliminating the sticking phenomenon, the passage for supplying the hydraulic oil to the end chamber 8 is provided. , And the configuration is simplified.

In the embodiment, a three-port valve is shown. However, the present invention can be applied to a two-port valve, and is not limited to a pilot portion of a pilot-operated valve. Is clear.

[0022]

As described above, according to the present invention, the pressure is increased in the end chamber on one end side of the valve hole, and the increased pressure acts on the valve body to push the valve body together with the operating force of the solenoid toward the operating position. In order to eliminate the sticking phenomenon of the valve body when moving from the normal position to the operating position, a small solenoid which cannot obtain a large operating force can be used without any trouble, and a small electromagnetic switching valve Can be obtained. Further, since the hydraulic oil leaked from the supply passage through the sliding portion between the valve body and the valve hole is used for pressure generation in the end chamber on one end side of the valve hole, the hydraulic oil to the end chamber is used. The provision of a passage for supply is not particularly necessary, and the configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electromagnetic switching valve showing one embodiment of the present invention.

[Explanation of symbols]

 1 body 2 valve body 3 valve hole 6 solenoid 7, 8 end chamber 9 through hole 10 spring receiving body 11 pressing body 11A shut off part 12 spring P supply passage A output passage R discharge passage

Claims (1)

(57) [Claims] 1. A solenoid valve, which is slidably received in a valve hole of a main body, is pushed to a normal position by a pressing force of a spring toward one end of the valve hole, and is provided on a main body at one end of the valve hole. A hydraulic electromagnetic switching valve having a valve body that is pressed and moved toward the other end of the valve hole against the pressing force of the spring toward the operating position by the operating force, and at both ends of the valve body in the valve hole, An end chamber for receiving the hydraulic oil leaking through a sliding portion between the valve body and the valve hole is formed, and a discharge passage communicating the other end chamber of the valve hole to the tank side is provided in the main body. Also, a hydraulic pressure source is provided in the valve body through an axially extending through hole that communicates the end chamber on one end side of the valve hole to the end chamber on the other end side, and communicates with the valve hole at locations separated from each other in the axial direction. The supply passage communicating with the valve and the output passage, which is cut off from the supply passage in response to the movement of the valve element, are provided at a position that is one end of the valve hole from the output passage. A supply passage is provided in the main body so as to communicate with the valve hole, and the spring is pressed against the valve body to the normal position by the pressing force of the spring, and the valve body is moved to the operating position by the operating force of the solenoid. A pressing body that comes into contact with the valve body to be pressed is provided. An electromagnetic switching valve for hydraulics, which can be brought into contact with a spring receiver so as to release the contact of the spring receiver with the valve prior to contact.