JPH11182725A - Solenoid valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce action resistance caused by expansion and compression of gas generated at the time of action and eliminate instability of action caused by machining. SOLUTION: In a movable iron core 3, band-like large diameter parts 3f, 3g short in the axial length L1, L2, with outer diameters D1, D2 larger than the diameters D3, D4 of other parts 3d, 3e and slightly smaller than the inner diameter D5 of a guide pipe 2 are formed at an end 3b and a position 3c slightly inward from the side edge 2a of a valve element 4 of a guide pipe 2 in the most protruded position of the valve element 4 in a sliding stroke L. The diameter D3 is set to such dimension that the movable iron core 3 does not come in contact with the side edge 2a of the valve element 4 of the guide part 2 when the movable iron core 3 is inclined to the maximum in relation to the guide pipe 2 in the sliding stroke L. The pressure rise and drop quantity of gas between the movable iron core 3 and a fixed iron core 11 impeding the action of the movable iron core can therefore be suppressed low, so that the movable iron core 3 can smoothly act, and electric power required for reset action is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve which is used as a shut-off actuator of a gas microcomputer meter having a built-in gas shut-off device for preventing a gas accident, or used for opening and closing a gas passage of a gas appliance. It is.

[0002]

2. Description of the Related Art Conventionally, many solenoid valves have been used in gas shut-off devices and gas appliances for preventing gas accidents.
Hereinafter, a conventional solenoid valve will be described.

A conventional solenoid valve is disclosed in Japanese Patent Application Laid-Open No. H7-71636. FIG. 3 shows a sectional view of the solenoid valve. FIG. 3A shows the valve open state, and FIG. 3B shows the valve closed state.

3 (a) and 3 (b), an electromagnetic coil 51, a guide pipe 52 disposed inside the electromagnetic coil 51, and a cylindrical movable member slidably disposed inside the guide pipe 52 are shown. An iron core 53, a valve element 54 disposed at an end 53 a of the movable iron core 53 protruding from the guide pipe 52, and a spring 57 for urging the valve element 54 against a valve seat 56 provided in a gas flow path 55. And constitute a solenoid valve.

[0005] The movable iron core 53 has a sliding section of approximately D
The outer periphery is missing so as to form a mold, that is, a groove 53f is formed in the outer periphery. Valve 54 of movable iron core 53
The fixed iron core 61 is arranged to face the end 53b where no is provided, one pole of the permanent magnet 62 is arranged at the other end of the fixed iron core 61, and the other end is in contact with and surrounds the electromagnetic coil 51 and the yoke. 6
3,64 are arranged.

Gasket members 65 and 66 are disposed between the guide pipe 52 and the fixed iron core 61 and between the guide pipe 52 and the yoke 64, respectively.
5 and airtightness.

With respect to the solenoid valve configured as described above,
The operation will be described below. In the valve open state of FIG. 3A, the movable iron core 53 comes into contact with the fixed iron core 61 and the permanent magnet 6
2, the fixed iron core 61, the movable iron core 53, and the yoke 64, 63 constitute a magnetic circuit with a strong permanent magnet, and the movable iron core 53 is fixed against the urging force of the spring 57 by its electromagnetic force. The valve body 54 is maintained in a state of being adsorbed to the valve seat 5.
6 and keep the valve open state.

At the time of the cutoff operation, a current is applied to the electromagnetic coil 51 so as to generate a magnetomotive force in a direction opposite to the magnetomotive force of the permanent magnet 62, and the electromagnetic force between the fixed iron core 61 and the movable iron core 53 decreases. The movable iron core 53 is urged by the urging force of the spring 57.
Moves to the valve seat 56 side, the valve element 54 contacts the valve seat 56, and the gas passage 55 is shut off as shown in FIG.

In the valve closed state, the fixed iron core 61 and the movable iron core 53 are separated by a stroke L ', so that the magnetic circuit by the permanent magnet 62 is weak, and the fixed iron core 61 and the movable iron core 53 are weak. Of the spring 57
The valve body 54 keeps the valve closed state in contact with the valve seat 56 by the urging force of (1).

At the time of the return operation, a current is applied to the electromagnetic coil 51 so as to generate a magnetomotive force in the same direction as that of the permanent magnet 62, and the electromagnetic force between the fixed iron core 61 and the movable iron core 53 increases. The movable iron core 53 against the urging force of the spring 57
Is sucked into the fixed iron core 61, the valve element 54 is detached from the valve seat 56, and returns to the state of FIG. Alternatively, an external force in a direction opposite to the urging force of the spring 57 is applied to the movable iron core 53 or the valve
4 is detached from the valve seat 56, and returns to the state of FIG.

During the shut-off / return operation, the gas between the movable iron core 53 and the fixed iron core 61 expands and compresses, resulting in a load that hinders the operation of the movable iron core 53. In the case of the solenoid valve of this example, the movable iron core 53 Gas passes through the outer peripheral groove 53f of the
Since it circulates with the outside, excessive expansion / compression does not occur, and the movement of the movable iron core 53 is hardly hindered by gas.

[0012]

However, in the above-described conventional configuration, the outer peripheral groove 53f of the movable iron core 53 is formed separately from the other cylindrical outer peripheral surface that can be machined by a lathe or the like. In addition, there is a problem that an additional process such as milling is required, and the movable iron core 53 is expensive.

Further, processing burrs are likely to be generated at the ridge between the outer peripheral groove 53f and the other outer peripheral surface, and the processing burrs are caught on the surface of the guide pipe 52 to destroy the solid lubricating film of the guide pipe 52 or to slide. There is a problem that the operation becomes unstable due to an increase in the dynamic resistance, or the processing burr is lost, the suction is caused between the movable iron core 53 and the fixed iron core 61 and the contact between the two is hindered, and the suction becomes unstable. there were.

The details will be described below with reference to the drawings. FIG. 4 is a perspective view of the movable iron core 53 of the solenoid valve of FIG. In FIG. 4, the movable iron core 53 is first cut from a cylindrical material while forming processing marks 53g by milling, and then cut in the direction of 53h by lathe processing. At this time, the processing burr 53 reflecting the mountain valley of the processing mark 53g on the ridge 53i.
j occurs. This processing burr 53j causes the above-mentioned operation instability.

In addition, the above-mentioned milling is more likely to have a rough surface than lathing or polishing, and as a result, the grooves 5
3f has a large surface area, is more likely to be corroded than other portions, and causes the corrosion resistance of the movable iron core 53 to be reduced.

In view of the above-mentioned conventional problems, the present invention does not process an outer peripheral groove which causes local wear, operation instability and deterioration of corrosion resistance on a movable iron core. It is an object of the present invention to provide an electromagnetic valve which allows a gas between a movable iron core and a fixed iron core to flow during operation, and which does not hinder the movement of the movable iron core.

[0017]

In order to solve the above-mentioned conventional problems, the present invention has an electromagnetic coil, a guide pipe disposed inside the electromagnetic coil, and a slide pipe disposed inside the guide pipe. In an electromagnetic valve configured by a movable iron core, a valve body disposed at an end of the movable iron core protruding from a guide pipe, and a spring that biases the valve body against a valve seat provided in a gas flow path. The movable iron core is thicker than the other part at the end on the side without the valve element and at a position slightly inside the valve element side end of the guide pipe at the position where the valve element protrudes most in the sliding stroke. A band-shaped large-diameter portion having a slightly smaller outer diameter and a shorter axial length is formed.

According to the above-mentioned invention, the movable iron core which is expanded and compressed when performing the operation of shutting off (closing the valve) or returning (opening the valve)
Since the gas between the fixed iron cores can flow only through the flow path resistance of the two large-diameter portions having a short axial length, the outer periphery of the movable iron core causes local wear, unstable operation, and reduced corrosion resistance. It is possible to provide an electromagnetic valve in which the movement of the movable iron core is hardly hindered by the gas without processing the groove.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides an electromagnetic coil, a guide pipe disposed inside the electromagnetic coil, and a movable iron core slidably disposed inside the guide pipe. And a valve body disposed at an end of the movable iron core protruding from the guide pipe, and a spring configured to bias this valve body against a valve seat provided in the gas flow path,
The movable iron core is thicker than the other part at the end on the side without the valve element and at a position slightly inside the valve element side end of the guide pipe at the position where the valve element protrudes most in the sliding stroke, and is larger than the inner diameter of the guide pipe. A solenoid valve characterized in that a strip-shaped large-diameter portion having a slightly thin outer diameter and a short axial length is formed.

The gas between the movable iron core and the fixed iron core, which is expanded and compressed when performing the shut-off (closing the valve) and the return (opening of the valve) operation, is supplied to the two large-diameter tubes having a short axial length. Because it is possible to circulate only by the flow path resistance of the part, the gas does not hinder the movement of the movable iron core without machining the outer peripheral groove which causes local wear, operation instability, deterioration of corrosion resistance on the movable iron core, As a result, it is possible to provide an electromagnetic valve having low power required for the return (opening) operation.

According to a second aspect of the present invention, the diameter of the small-diameter portion drawn into the guide pipe in the sliding stroke on the valve body side on the valve body side from the large-diameter portion on the valve body side of the movable iron core is determined by the sliding stroke. 2. The solenoid valve according to claim 1, wherein the movable iron core is formed so as to be thin so as not to contact the end of the guide pipe on the valve body side even when the movable iron core is inclined to the maximum with respect to the guide pipe.

When the shut-off (closing valve) and return (opening) operations are performed, the end of the guide pipe on the valve body side does not contact the movable iron core. The dynamic contact portion is not limited and is distributed over a wide range equivalent to the sliding stroke between the valve body side and the side without the valve body, so that the solid lubricating film of the guide pipe is evenly worn and the operating durability of the entire solenoid valve Can be improved.

According to a third aspect of the present invention, the inner surface of the guide pipe is located further to the end than the large-diameter portion of the movable iron core on the side where the valve element is not provided, even when the movable iron core is maximally inclined with respect to the guide pipe. Forming a small-diameter portion having a diameter and a short axial length that does not come into contact with the surface, the surface from the large-diameter portion to the small-diameter portion has a gentle curve and an inclination greater than the maximum inclination angle of the movable iron core and the guide pipe. 3. The solenoid valve according to claim 1, wherein the solenoid valve is formed by a conical surface having a corner.

Further, since the sliding contact portion of the guide pipe and the movable iron core on the side where the valve element is not provided is formed with a gentle curve, the sliding resistance is low, and the outer peripheral portion generated in lathe processing is cut off from the outer peripheral portion. By providing a small step in the conical surface due to switching of the cutting tool with the end, the step and processing burrs do not contact the guide pipe, so that there is provided an electromagnetic valve in which local wear and operation instability hardly occur. it can.

A fourth aspect of the present invention is the solenoid valve according to the second or third aspect, wherein a solid lubricating film is formed on an inner surface of the guide pipe.

The sliding contact portion is not limited to one end of the guide pipe on the valve body side, and the wear of the fixed iron core on the side without the valve body is small, so that the amount of wear of the solid lubricating film can be suppressed. A durable third-party solenoid valve can be made.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1A shows the open state of the solenoid valve according to the first, second and fourth aspects of the present invention, and FIG. 1B shows the closed state of the solenoid valve. A sectional view of the state is shown.

1A and 1B, an electromagnetic coil 1 and a guide pipe 2 arranged inside the electromagnetic coil 1 are shown.
A cylindrical movable iron core 3 slidably disposed inside the guide pipe 2; a valve element 4 disposed at an end 3 a of the movable iron core 3 protruding from the guide pipe 2; And a spring 7 for urging the valve seat 6 provided in the gas flow path 5 to form a solenoid valve.

The movable iron core 3 has an end 3 b on the side without the valve element 4,
The other portion is located at a position where the valve element 4 projects most in the sliding stroke L, that is, a position 3c slightly inside the end 4a of the guide pipe 2 on the valve element 4 side in the closed state shown in FIG. Bands 3f and 3g, which are thicker than the diameters D3 and D4 of 3d and 3e, have outer diameters D1 and D2 slightly smaller than the inner diameter D5 of the guide pipe 2, and have short axial lengths L1 and L2 are formed. .

The diameter D3 is such that the movable iron core 3 does not come into contact with the valve element 4 side end 2a of the guide pipe 2 even when the movable iron core 3 is maximally inclined with respect to the guide pipe 2 within the sliding stroke L. Is set to Guide pipe 2
Has a solid lubricating film formed on the inner surface thereof.

The diameter D of the movable iron core 3 for smooth sliding
1 and D2 are formed slightly smaller than the diameter D5 of the guide pipe 2. For this reason, the central axis of the movable iron core 3 may be inclined with respect to the central axis of the guide pipe 2, and when the central axis of the solenoid valve is installed horizontally, the central axis of the solenoid valve is affected by gravity. Even in the case where are vertically arranged, the center axis of the movable iron core 3 is often inclined with respect to the center axis of the guide pipe 2 due to the eccentric load of the spring 7.

End 3 of movable iron core 3 on which valve element 4 is not arranged
The fixed iron core 11 is arranged opposite to the fixed iron b, one pole of the permanent magnet 12 is arranged at the other end of the fixed iron core 11, and yoke 13 and 14 are arranged so as to abut on the other pole and surround the electromagnetic coil 1. ing. Gasket members 15 and 16 are arranged between the guide pipe 2 and the fixed iron core 11 and between the guide pipe 2 and the yoke 14, respectively, to provide airtightness between the electromagnetic coil 1 and the gas flow path 5. .

With respect to the solenoid valve configured as described above,
The operation will be described below. In the valve open state of FIG. 1A, the movable iron core 3 abuts on the fixed iron core 11 and the permanent magnet 1
2, a fixed iron core 11, a movable iron core 3, and a yoke 14, 13 constitute a magnetic circuit with a strong permanent magnet, and the movable iron core 3 is fixed to the fixed iron core 1 against the urging force of the spring 7 by its electromagnetic force.
1, the valve body 4 maintains the valve-open state away from the valve seat 6. At this time, the points of contact of the guide pipe 2 with the movable iron core 3 are the points 2b and 2c in FIG.
It is.

During the shut-off operation, a current is applied to the electromagnetic coil 1 so as to generate a magnetomotive force in the direction opposite to the magnetomotive force of the permanent magnet 12, and the electromagnetic force between the fixed iron core 11 and the movable iron core 3 decreases. The movable iron core 3 is moved by the urging force of the spring 7 to the valve seat 6.
And the valve body 4 comes into contact with the valve seat 6, and the gas passage 5 is shut off as shown in FIG. At this time, the movable iron core 3 moves while being in contact with the points 2b to 2d and the points 2c to 2e of the guide pipe 2.

In the valve closed state, the fixed iron core 11 and the movable iron core 3 are separated by a stroke L, so that the magnetic circuit by the permanent magnet 12 is weak. Because the electromagnetic force is weak, the valve body 4 keeps the valve closed state in contact with the valve seat 6 by the urging force of the spring 7.
At this time, the contact points of the guide pipe 2 with the movable iron core 3 are points 2d and 2e.

During the return operation, a current is applied to the electromagnetic coil 1 so as to generate a magnetomotive force in the same direction as the magnetomotive force of the permanent magnet 12, and the electromagnetic force between the fixed iron core 11 and the movable iron core 3 increases. The movable iron core 3 is attracted to the fixed iron core 11 against the urging force of the spring 7, and the valve element 4 is separated from the valve seat 6.
Returning to the state shown in FIG. 7A, the gas passage 5 is returned. At this time, the movable iron core 3 moves while contacting the points 2d to 2b and the points 2e to 2c of the guide pipe 2.

As described above, the sliding portion of the guide pipe 2 at the time of the start of the shut-off and the return is such that the tip 2d side of the movable iron core 3 is at the point 2b.
From the point 2c to the point 2e on the valve element 4 side, and both ends 3 of the portion of the movable iron core 3 having the diameter D1.
b, 3c, and the end 2a on the valve body 4 side of the guide pipe 2 does not contact the movable iron core 3. Therefore, the guide pipe 2
The sliding contact portion is dispersed over the same sliding length, that is, the sliding stroke L, in a wide range on both the valve body 4 side and the side without the valve body 4, so that the wear of the solid lubricating film of the guide pipe 2 is made uniform. In addition, the operation durability of the entire solenoid valve can be improved.

The guide pipe 2 is widely formed by forming a metal plate into a tubular shape having a bottom by drawing, and then punching the bottom to form a pipe. Usually arranged on the valve body side. In such a guide pipe, small burrs are often left at the punched portion, that is, at the end on the valve body side. Sometimes.

In the solenoid valves shown in FIGS. 1 (a) and 1 (b),
Since the movable iron core 3 is formed so as not to contact the end 2 a of the guide pipe 2 on the valve body 4 side even when the movable iron core 3 is inclined to the maximum with respect to the guide pipe 2, the possibility of dropping the burr is low and lubrication is low. Sliding can be expected.

In general, during the shutoff / return operation (particularly during the return operation), the gas between the movable iron core and the solid iron core expands and compresses, resulting in a load that hinders the operation of the movable iron core. The expanded / compressed gas flows through the gas passage from the gap between the movable iron core and the guide pipe. The pressure loss due to frictional resistance during the flow of the gas, that is, the pressure rise / fall amount of the gas between the movable iron core and the fixed iron core, is determined by the flow path, that is, the length of the gap between the movable iron core and the guide pipe and the unit. It is known that it is proportional to the product of the surface areas, ie, the surface area, and inversely proportional to the cross-sectional area.

That is, if the gap between the movable iron core and the guide pipe is widened, the operating resistance due to expansion and compression of gas between the movable iron core and the fixed iron core can be reduced.
Conversely, if the gap is large, the play between the movable iron core and the guide pipe is large, the mechanical sliding resistance varies, and the shutoff / return operation becomes unstable.

In the solenoid valve shown in FIGS. 1A and 1B, the large diameter portions 3f and 3g of the movable iron core 3 serving as a sliding guide between the movable iron core 3 and the guide pipe 2 are formed by a guide pipe. Outer diameters D1 and D2 slightly smaller than the inner diameter D5 that can be slid
That is, in the large-diameter portions 3f and 3g, the gap between the movable iron core 3 and the guide pipe 2 is formed to have substantially the same cross-sectional area as that of the above-described ordinary solenoid valve, so that the shut-off / return operation is performed. The pressure loss per unit length of gas flow between the movable iron core 3 and the guide pipe 2 during
At f and 3g, it is almost the same as a normal solenoid valve.

However, the small diameter portion 3d of the movable iron core 3
The gap between the small diameter portion 3e and the guide pipe 2 is sufficiently large, that is, a large sectional area is secured in the flow path.
The pressure loss per unit length in d and 3e is sufficiently small as compared with a normal solenoid valve.

Since the axial lengths L1 and L2 of the large diameter portions 3f and 3g having a large pressure loss are formed short, the pressure of the gas flow between the movable iron core 3 and the guide pipe 2 during the shut-off / return operation. The sum of the losses, that is, the amount of gas pressure increase / decrease between the movable iron core 3 and the fixed iron core 11 that hinders the operation of the movable iron core 3 is suppressed to be low, and the movable iron core 3 can operate smoothly. .

The solid lubricating film formed on the inner surface of the guide pipe 2 includes the following means. Metal plating such as nickel and chrome. A composite in which fine particles of a resin or a metal compound having lubricity and abrasion resistance are dispersed in a metal plating solution and subjected to plating treatment, and at least on the inner diameter side of the surface, the resin or the metal compound is codeposited in a metal matrix. plating. Examples thereof include those obtained by coating fine particles of a resin or a metal compound having lubricity and abrasion resistance on a metal surface using a synthetic resin or the like as a binder.

The material of the material of the guide pipe 2 may be a nonmagnetic copper alloy such as nonmagnetic stainless steel or brass.

As the material of the movable iron core 3, magnetic stainless steel, steel, and those having a solid lubricating film formed on the surface thereof can be used. Solid lubricating film is guide pipe 2
Is the same as in the example. However, since the present invention has a movable iron core shape suitable for forming a solid lubricating film on the guide pipe 2 side, if the operation durability is acceptable in consideration of economy, the movable iron core 2 is prevented from being oxidized. A magnetic stainless steel or the like that does not need to form a solid lubricating film that is not treated is most suitable.

In this embodiment, the permanent magnet 12
Although the self-holding type solenoid valve having the above has been described above, the present invention can be applied to a solenoid valve without a permanent magnet used in many gas appliances.

Further, in the solenoid valve shown in FIG.
However, the present invention can be practiced with a solenoid valve without a fixed iron core, such as a gas proportional valve.

(Embodiment 2) The movable iron core 23 of the solenoid valve according to the third aspect is shown in FIG. FIG. 2A shows the movable iron core 2.
3 is a side view of the entirety, and FIG.
FIG. Other configurations are the same as those of the solenoid valve of FIG.

In FIG. 2, reference numeral 23a denotes an end on the valve body 4 side;
3b is the side without the valve element 4, that is, the end on the fixed iron core 11 side,
23d and 23e are small diameter portions, and 23f and 23g are large diameter portions. The movable iron core 23 is further located on the end 23b side than the large diameter portion 23f.
Is formed with a small-diameter portion 23h having a diameter D6 and a short axial length L3 that does not come into contact with the inner surface of the guide pipe 2 even when it is inclined to the maximum with respect to the guide pipe 2, and the large-diameter portion 23
The surface from f to the small-diameter portion 23h is constituted by a gentle curve R1 and a conical surface 23i having an inclination angle A1 larger than the maximum inclination angle of the movable iron core 23 and the guide pipe 2.

The movable iron core is generally formed by lathe processing, or lathe processing and outer diameter grinding. However, in lathe processing, minute iron generated by switching of a cutting tool performed because a cutting angle between an outer peripheral portion and an end is changed. Processing step and processing occur, and in the grinding process, since the end corner curve cannot be processed, the corner curve is formed by cutting in advance, and then the minute edge generated when the outer peripheral portion is finished by grinding. It is inevitable that processing steps and processing burrs occur.

In the movable iron core 23 shown in FIG. 2, the processing burr and the processing step are set at the intersection 23j between the conical surface 23i and the small diameter portion 23h.

FIG. 2 (b) schematically shows the tool feed curve in the cutting process. First, the outer circumference cutting tool cuts the outer circumference as indicated by a curve 23k, and separates from the movable iron core 23 at an intersection 23j between the conical surface 23i and the small diameter portion 23h. Next, the end face cutting tool is moved to the intersection 23j as shown by the curve 23l.
, And the end 23b is cut through the curve R2. Therefore, the processing step and the processing burr are generated at the intersection 23j in the conical surface 23i, and the processing can be performed so as not to contact the guide pipe 2.

In the solenoid valve using the movable iron core 23 formed as described above, the guide pipe 2 and the sliding contact portion 23f on the non-valve side of the movable iron core 23 have a gentle curve R1.
, The sliding resistance is low, and the outer peripheral portion 23f and the cut-off end portion 23 generated during lathe processing are formed.
The small step due to the switching of the cutting tool to b causes the conical surface 23i
Since the step and the processing burr do not contact the guide pipe 2, local wear and operation instability hardly occur.

A similar shape may be set for the large-diameter portion 23g. In this case, a gentle curve R3 from the large-diameter portion 23g to the small-diameter portion 23d is provided on the end 23a side, the movable iron core 23 and the guide pipe. By forming the conical surface 23m having an inclination angle larger than the maximum inclination angle of 2, it is possible to realize a similarly low sliding resistance.

[0058]

As described above, according to the solenoid valve of the present invention,
The following effects are obtained.

The movable iron core is thicker than the other parts at the end on the side where there is no valve element and at the position where the valve element protrudes most within the sliding stroke and at a position slightly inside the valve element side end of the guide pipe. A belt-shaped large-diameter portion with an outer diameter slightly smaller than the inner diameter of the pipe and a short axial length is formed, so that it is tensioned and compressed when performing a shut-off (closing valve) or a return (opening valve) operation. The gas between the movable iron core and the fixed iron core can flow only through the flow path resistance of the two large-diameter portions having a short axial length, so that the movable iron core has local wear, unstable operation, and reduced corrosion resistance. The gas does not hinder the movement of the movable iron core without processing the outer peripheral groove that causes the problem, and as a result, it is possible to provide an electromagnetic valve that requires low power for the return (opening) operation.

In addition, the movable iron core guides the diameter of the small-diameter portion drawn into the guide pipe in the sliding stroke on the valve body side more than the large-diameter portion on the valve body side of the movable iron core. Even when the guide pipe is tilted to the maximum, it is so thin that it does not come into contact with the valve body side end of the guide pipe. Since the body side end does not contact the movable iron core, the sliding contact portion is not limited to one point on the valve body side end of the guide pipe, but is dispersed over a wide range equivalent to the sliding stroke of the valve body side and the side without the valve body. Therefore, the wear of the fixed lubricating film of the guide pipe is made uniform, and the operation durability of the entire solenoid valve can be improved.

Further, at a position further from the large diameter portion of the movable iron core on the side where the valve element is not provided, a short shaft having a diameter that does not contact the inner surface of the guide pipe even when the movable iron core is inclined to the maximum with respect to the guide pipe. A small-diameter portion having a length in the direction is formed, and the surface from the large-diameter portion to the small-diameter portion is formed by a gentle curve and a conical surface having an inclination angle larger than the maximum inclination angle of the movable iron core and the guide pipe. As a result, the sliding contact portion of the guide pipe and the movable iron core on the side where the valve element does not have the valve body is formed with a gentle curve, so that the sliding resistance is low, and the outer peripheral portion and the cut-off end portion generated in the lathe processing. By setting a small step in the conical surface due to the switching of the cutting tool between the above and the above, since the step and the processing burr do not contact the guide pipe, it is possible to provide an electromagnetic valve in which local wear and operation instability hardly occur.

Further, since the fixed lubricating film is formed on the inner surface of the guide pipe, the sliding contact portion is not limited to one point on the valve body side end of the guide pipe, and the fixed iron core is worn by the end on the side where the valve body does not have the valve body. Therefore, the amount of wear of the solid lubricating film can be suppressed, and a highly durable solenoid valve can be manufactured.

[Brief description of the drawings]

FIG. 1A is a sectional view of an electromagnetic valve in an open state according to a first embodiment of the present invention. FIG. 1B is a sectional view of the solenoid valve in a closed state.

2A is a side view of a movable iron core of an electromagnetic valve according to a second embodiment of the present invention. FIG. 2B is an enlarged view of an end of the movable iron core on a side where no valve element is provided, and FIG. Schematic diagram of tool feed curve

FIG. 3A is a cross-sectional view of a conventional solenoid valve in an open state. FIG. 3B is a cross-sectional view of the conventional solenoid valve in a closed state.

FIG. 4 is a perspective view of the movable iron core of the solenoid valve.

[Explanation of symbols]

Reference Signs List 1 electromagnetic coil 2 guide pipe 3, 23 movable iron core 4 valve body 5 gas flow path 6 valve seat 7 spring L sliding stroke 8 coil bobbin 3d, 23d, 3e, 23e, 23h movable iron core small diameter portion 3f, 23f, 3g, 23g Large diameter part of movable iron core 23i Conical surface

Claims (4)

[Claims] An electromagnetic coil, a guide pipe disposed inside the electromagnetic coil, a movable iron core slidably disposed inside the guide pipe, and a movable core projecting from the guide pipe of the movable iron core. In a solenoid valve composed of a valve body disposed at an end and a spring that biases the valve body against a valve seat provided in a gas flow path, the movable iron core is an end on a side without a valve body. At a position where the valve element protrudes most in the sliding stroke, at a position slightly inside the end of the guide pipe on the valve element side, an outer diameter that is thicker than other parts and slightly smaller than the inner diameter of the guide pipe has an axial length. Solenoid valve with a short band-shaped large diameter part. 2. The movable iron core guides the diameter of the small-diameter portion drawn into the guide pipe in the sliding stroke on the valve body side further than the large-diameter portion on the valve body side of the movable iron core. 2. The solenoid valve according to claim 1, wherein the solenoid valve is formed so as not to be in contact with the valve body side end of the guide pipe even when the guide pipe is inclined to the maximum. 3. A further short end of the movable iron core having a diameter that does not contact the inner surface of the guide pipe even when the movable iron core is tilted to the maximum with respect to the guide pipe. A small-diameter portion having a length in the direction is formed, and the surface from the large-diameter portion to the small-diameter portion is formed by a gentle curve and a conical surface having an inclination angle larger than the maximum inclination angle of the movable iron core and the guide pipe. The solenoid valve according to claim 1. 4. The solenoid valve according to claim 2, wherein the guide pipe has a solid lubricating film formed on an inner surface thereof.