JPH0143582Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an electromagnetic flow control valve that controls the flow rate of pressure fluid flowing from a high-pressure side flow path to a low-pressure side flow path in accordance with a control current applied to a solenoid. .

<Prior art> As an electromagnetic flow control valve, a cylindrical spool is fitted into the inner hole of the valve body so as to be slidable in the axial direction, and a slit cut out in the axial direction at the inner end of the spool allows the spool to be inserted into the valve body. Some devices have a bypass passage whose opening area with the port changes depending on the axial displacement of the bypass passage.

In such an electromagnetic flow control valve, a flow force F1 acts on the spool 20 in a direction that narrows the opening degree of the bypass passage due to the influence of the pressure fluid flowing through the bypass passage, which adversely affects the control of the opening degree.

In order to eliminate the adverse effects of the flow force acting on the spool, the applicant has previously filed a utility model registration application (Utility Model Application No. 58-40275) for an electromagnetic flow control valve.

As shown in Fig. 1, this electromagnetic flow control valve has a cut end surface 3 of a slit 2 of a spool 1 that is inclined from the outer circumference toward the center of the spool and toward the inner end of the spool. A force F2 in the opposite direction to the flow force F1 is applied to the spool 1 by actively colliding the pressure fluid A against the inclined cutting end surface,
This prevents changes in the opening degree of the bypass passage due to the flow force F1.

In this device, when the bypass passage has a small opening, the force F2 in the opposite direction to the flow force F1 due to the pressure fluid colliding with the cut end surface 3 is large;
This force F2 acts on the spool 1 in the direction of opening the bypass passage, resulting in a problem of increased flow sensitivity. In addition, when the bypass passage is slightly opened, the force F2 is unstable due to fluctuations in the flow of the pressure fluid, causing an unstable phenomenon such as displacing the spool 1 in the axial direction, and reducing the flow rate of the fluid passing through the bypass passage. There were problems with instability or hydraulic vibration.

<Purpose of the invention> The present invention was made to solve this problem, and its purpose is to reduce the flow sensitivity at the minute opening of the bypass passage and to prevent the unstable phenomenon of the spool. , to prevent unstable flow rate or hydraulic vibration of the fluid that has passed through the bypass passage.

<Configuration of the invention> The electromagnetic flow control valve according to the invention has a wide first slit at the inner end of the spool and a narrow second slit continuous with the first slit in the axial direction of the spool. The cut end surface of the first slit is formed to be a surface that slopes from the outer circumference toward the center of the spool toward the inner end of the spool, and the cut end surface of the second slit is formed to be a surface that slopes toward the inner end of the spool. It is characterized by being formed on a surface perpendicular to.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. In FIG. 2, reference numeral 32 denotes a mounting base. A through hole 32a is formed in this mounting base 32, and a protrusion 10a of the valve body 10 made of a magnetic material is liquid-tightly inserted into the large diameter portion of the through hole 32a. It is fitted. This protrusion 10a is provided with a port 12 that opens to the first flow path _P1 and an inner hole 11 that communicates with this port 12. Further, a union 24 made of a non-magnetic material such as stainless steel is screwed onto the inner end of the protrusion 10a, and the inner end of the union 24 is fluid-tightly fitted into the small diameter portion of the through hole 32a. The union 24 has a port 13 which has one end open to the second flow path _P2 and the other end opened to the inner hole 11.
is formed.

A yoke 27 made of a magnetic material is fitted and fixed inside the sleeve 26 which is fixed to the outer end protrusion of the valve body 10 by brazing or the like. A spacer ring 50 made of a non-magnetic material is interposed between them. A cylindrical portion 27 is provided at the inner end of the yoke 27 and accommodates the outer end of the cylindrical spool 20 while allowing a predetermined stroke.
a is formed.

A solenoid 29 wound around a bobbin 28 made of a non-magnetic material is provided on the outer periphery of the sleeve 26, and the inner end is connected to the valve body 1 surrounding the solenoid 29.
A cover 15 made of a magnetic material and bonded to the yoke 27 is fixed to the upper end of the yoke 27 with bolts 16.

The cylindrical spool 20 is made of a magnetic material,
It is slidably fitted into the inner hole 11 of the valve body 10 and is normally held at the lower end joined to the union 24 by the bias of a non-magnetic spring 25 made of stainless steel or the like housed in the inner hole 27b of the yoke 27. has been done.

On the other hand, this spool 20 has a large diameter hole 35 and a small diameter hole 36 formed in its center as shown in FIG. A first slit 21 with a wide width for bypass is formed over a predetermined length in the axial direction, and a second slit with a narrow width for bypass is continuous to the first slit 21 toward the spring 25 side.
A slit 40 is formed over a predetermined length in the axial direction.

These slits 21 and 40 are configured such that communication with the port 12 is cut off when the spool 20 is at the lower end position, and a bypass passage communicating between the ports 12 and 13 is formed by upward displacement of the spool 20. It's summery.

The first slit 21 on the spring 25 side is provided with a cut end surface 37 that slopes from the outer periphery toward the center and toward the inner end of the spool 20, while the second slit 40 on the spring 25 side is provided with a cut end surface 37 that slopes toward the inner end of the spool 20. It has a cut end surface 41 that is perpendicular to the axis of the spool 20.

When only the port 12 and the second slit 40 correspond to a small opening of the bypass passage, the second slit 4
Since the width of 0 is small, the opening area of the bypass passage is small, and the jet of pressure fluid does not collide with the cut end surface 41, so that no force is exerted on the spring 25 side of the spool 20 due to the jet of pressure fluid. port 12
When the opening of the bypass passage corresponds to that of the first slit 21, a part of the jet of pressure fluid collides with the notch end surface 37, and a force of this jet of pressure fluid acts on the spring 25 side of the spool 20. I'm starting to do that.

In the electromagnetic flow control valve configured as described above, when a current is applied to the solenoid 29, the solenoid 29
The suction force overcomes the biasing force of the spring 25 and the spool 20 begins to be displaced upward. port 12
In the small opening state of the bypass passage where only the second slit 40 corresponds, the pressure fluid flows from the first flow passage _P1 to the port 12, the second slit 40, and the port
and flows into the second flow path _P2 . In this case, since the width of the second slit 40 is small, the flow rate passing through the bypass passage is small, and the flow rate sensitivity can be lowered.

When passing pressure fluid from the first flow path _P1 to the second flow path _P2 , a downward flow force F1 acts on the spool 20, but since the flow rate passing through the bypass passage is small, the flow force on the spool 20 The influence of F1 is small. Since the jet of pressure fluid does not collide with the notch end surface 41, no force is applied to the spool 20 to open the bypass passage, and the flow rate sensitivity can be lowered. It does not cause the same unstable phenomenon as when displacement in the direction. Therefore, precise flow control can be performed. When the spool 20 moves further upward due to the suction force of the solenoid 29 and the port 12 and the first slit 21 come into contact with each other, more pressure fluid flows into the first flow path P than when the bypass passage is opened at a small opening. ₁
The water then flows through the port 12, the first slit 21, the second slit 40, and the port 13 to the second flow path _P2 . In this case, when passing the pressure fluid from the first flow path _P1 to the second flow path _P2 , a downward flow force F1 acts on the spool 20, and due to the influence of this flow force F1, the spool 20 attempts to move to a position different from the position determined by the suction force, that is, in a direction that attempts to narrow the bypass passage.

However, since the cut end surface 37 is formed to be inclined, a part of the pressure fluid flowing from the first flow path P ₁ to the second flow path P ₂ directly collides with this cut end surface 37 . A reaction force F2 in a direction opposite to the flow force F1 is applied to the cut end surface 37.
Therefore, the flow force F1 is offset by the reaction force F2, so the spool 20 is moved only by the suction force of the solenoid 29, and the opening degree of the bypass passage can be accurately controlled.

<Effects of the invention> As described above, in the present invention, there is a first slit with a wide width at the inner end of the spool, and a second slit with a narrow width in the axial direction of the spool, which is continuous with the first slit. Since the bypass passage is formed, the opening area of the bypass passage becomes small when the bypass passage is slightly opened, and the flow rate sensitivity can be lowered. or,
Since the cut end surface of the second slit is formed perpendicular to the axis of the spool, the force that tries to open the bypass passage on the spool due to the fluid force at the minute opening of the bypass passage does not act, which reduces the flow rate sensitivity. On the other hand, there are advantages in that the instability of the spool can be prevented, and the flow rate of the fluid passing through the bypass passage can be prevented from becoming unstable or hydraulic vibration can be prevented. As a result, precise flow control can be performed.

Further, when the bypass passage corresponding to the port and the first slit is opened, the cut end surface of the first slit is formed into a surface that slopes from the outer circumference toward the center of the spool and toward the inner end of the spool. Therefore, the pressure fluid flowing in from the port can collide with the inclined notch end face of the first slit to exert a reaction force in the direction opposite to the flow force, thereby preventing changes in the opening degree of the bypass passage due to the flow force. This has the advantage of allowing accurate flow control.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of the electromagnetic flow control valve of the earlier application.
Figure 2 is a sectional view of the electromagnetic flow control valve of the present invention;
The figure is an enlarged sectional view of the main part of FIG. 10...Valve body, 11...Inner hole, 12,1
3...Port, 20...Spool, 21...1st
25... spring, 29... solenoid, 37... cut end surface, 40... second slit, 41... cut end surface.

Claims (1)

[Scope of utility model registration request] A valve body having two ports each communicating with two channels through which high-pressure fluid and low-pressure fluid flow, and an inner hole opening to these ports, and a valve body having a notch cut out in the radial direction from the inner end thereof. a cylindrical spool having a slit, the slit forming a bypass passage whose opening area changes according to axial displacement within the inner hole of the valve body;
In an electromagnetic flow control valve comprising a solenoid to which a control current is applied and a spring that biases the spool in a direction in which the slit closes the bypass passage, the slit has a wide first slit and a first slit with a wide width. The first slit is connected to a second slit having a narrower width, and the cut end surface of the first slit is inclined from the outer circumference toward the center of the spool and toward the inner end of the spool. An electromagnetic flow control valve characterized in that the cut end face of the second slit is formed in a plane perpendicular to the axis of the spool.