Solenoid valve

Abstract

Provided is a solenoid valve comprising a movable iron core 3 and a fixed iron core 5 disposed so as to face the movable iron core 3. When an axial direction from the fixed iron core 5 toward the movable iron core 3 is set as one axial direction, the fixed iron core 5 is provided with a tapered protrusion 51 the diameter of which decreases in the one axial direction . and the movable iron core 3 is provided with a tapered recess 31 the diameter of which decreases in the one axial direction. The tapered recess 31 of the movable iron core 3 and the tapered protrusion 51 of the fixed iron core 5 come into contact with each other when the movable iron core 3 is attracted to the fixed iron core 5. The solenoid valve is capable of reducing the amount of abrasion powder generated by abrasion of the movable iron core 3 and the fixed iron core 5.　The tapered recess 31 of the movable iron core 3 and the tapered protrusion 51 of the fixed iron core 5 come into contact with each other by point contact, or the tapered recess 31 of the movable iron core 3 and the tapered protrusion 51 of the fixed iron core 5 come into contact with each other by point contact while the movable iron core 3 becomes eccentric to the fixed iron core 5 by a sliding clearance amount with respect to a guide cylinder 4.

Description

Solenoid valve

[0001] This invention relates primarily to a solenoid valve used in combustion devices.

[0002] Conventionally, this type of solenoid valve comprises a valve body facing the valve seat within the valve housing, a movable core connected to one end of the valve body, a guide cylinder into which the movable core is slidably inserted, a fixed core positioned on the inner circumference of the other end of the guide cylinder so as to face the other end of the movable core, a valve spring that biases the movable core in a direction that isolates it from the fixed core, and an electromagnetic coil arranged to surround the guide cylinder. The axial direction from the fixed core toward the movable core is considered as one axial direction, and one end of the fixed core facing the other end of the movable core is provided with a tapered convex portion that decreases in diameter as it moves toward the one axial direction, while the other end of the movable core is provided with a tapered concave portion that also decreases in diameter as it moves toward the one axial direction. When the movable core is attracted to the fixed core, the tapered convex portion of the fixed core is inserted into the tapered concave portion of the movable core, and the tapered concave portion of the movable core and the tapered convex portion of the fixed core come into contact. In such a solenoid valve, the tapered recess of the movable core and the tapered convex portion of the fixed core are formed to have the same taper angle (see, for example, Patent Document 1).

[0003] Here, the movable iron core is manufactured to have a sliding clearance with respect to the guide cylinder. However, due to dimensional variations, the sliding clearance may exceed the dimension range expected in the design and become too large. In such a case, the following problems occur in the above conventional example. That is, when the movable iron core collides with the fixed iron core due to adsorption, the movable iron core is eccentric with respect to the fixed iron core by the amount of the sliding clearance with respect to the guide cylinder, and the generatrix portion of the peripheral surface of the tapered concave portion of the movable iron core and the generatrix portion of the peripheral surface of the tapered convex portion of the fixed iron core collide (that is, the generatrix portions collide by line contact) (see Fig. 2(a)). In particular, in the case where the solenoid valve is arranged in a posture where the axis is horizontal, the movable iron core is always eccentric downward with respect to the fixed iron core by the amount of the sliding clearance with respect to the guide cylinder due to its own weight. Therefore, as the movable iron core and the fixed iron core are adsorbed, the upper generatrix portions of the peripheral surfaces of the tapered concave portion of the movable iron core and the tapered convex portion of the fixed iron core repeatedly collide. As a result, the collision portion (line contact portion) between the movable iron core and the fixed iron core wears, and wear powder is generated from the movable iron core and the fixed iron core. In particular, in order to improve the sliding property of the tapered concave portion of the movable iron core with respect to the tapered convex portion of the fixed iron core, when a resin coating film is formed on the peripheral surface of the tapered convex portion of the fixed iron core and the peripheral surface of the tapered concave portion of the movable iron core, the resin coating film peels off due to the collision between the movable iron core and the fixed iron core, increasing the amount of wear powder generated. When the amount of wear powder generated increases, there is a risk that the wear powder will enter between the valve seat and the valve body, deteriorating the sealing performance of the solenoid valve.

[0004] Japanese Patent Application Laid-Open No. 2004-11893

[0005] In view of the above points, an object of the present invention is to provide a solenoid valve capable of reducing the amount of wear powder generated by the wear of the movable iron core and the fixed iron core.

[0006] To solve the above problems, the present invention comprises a valve body facing the valve seat within the valve housing, a movable core connected to one end of the valve body, a guide cylinder into which the movable core is slidably inserted, a fixed core positioned on the inner circumference of the other end of the guide cylinder so as to face the other end of the movable core, a valve spring that biases the movable core in a direction that isolates it from the fixed core, and an electromagnetic coil positioned to surround the guide cylinder, wherein the axial direction from the fixed core toward the movable core is considered as one axial direction, and one end of the fixed core facing the other end of the movable core is provided with a tapered protrusion that decreases in diameter as it moves toward the one axial direction, and the other end of the movable core In a solenoid valve in which a tapered recess is provided that decreases in diameter as it moves toward one side in the axial direction, and when the movable core is attracted to the fixed core, the tapered protrusion of the fixed core is inserted into the tapered recess of the movable core, and the tapered recess of the movable core and the tapered protrusion of the fixed core come into contact, the tapered recess of the movable core and the tapered protrusion of the fixed core come into contact by point contact, or when the movable core is eccentric with respect to the fixed core by the amount of sliding clearance with respect to the guide cylinder, the tapered recess of the movable core and the tapered protrusion of the fixed core come into contact by point contact.

[0007] According to the present invention, when the movable core and the fixed core collide due to adsorption, the collision area between the tapered recess of the movable core and the tapered convex portion of the fixed core is reduced compared to the conventional example in which the tapered recess of the movable core and the tapered convex portion of the fixed core collide by line contact. As a result, the area of ​​wear due to collision is reduced, and the amount of wear dust generated by the wear of the movable core and the fixed core is reduced.

[0008] Furthermore, in the present invention, it is preferable that the taper angle of the tapered recess of the movable core and the taper angle of the tapered convex portion of the fixed core are different angles. In this case, the tapered recess of the movable core and the tapered convex portion of the fixed core collide (contact) by point contact when the movable core is eccentric with respect to the fixed core by the amount of sliding clearance with respect to the guide cylinder. In this case, if the taper angle of the tapered convex portion of the fixed core is smaller than the taper angle of the tapered recess of the movable core, the tapered recess of the movable core and one end of the tapered convex portion of the fixed core in the axial direction collide by point contact when the movable core is eccentric as described above.

[0009] However, even if the taper angle of the tapered recess of the movable core is set to a different angle from the taper angle of the tapered convex portion of the fixed core, depending on the angle difference between these taper angles, when the movable core is tilted relative to the guide cylinder and the outer circumferential surface of the other end of the movable core is in contact with the inner circumferential surface of the guide cylinder, the tapered recess of the movable core and the tapered convex portion of the fixed core may collide by line contact. For this reason, in the present invention, it is preferable to set the angle difference between the taper angle of the tapered convex portion of the fixed core and the taper angle of the tapered recess of the movable core so that the tapered recess of the movable core and the tapered convex portion of the fixed core do not collide by line contact even when the movable core is tilted relative to the guide cylinder and the outer circumferential surface of the other end of the movable core is in contact with the inner circumferential surface of the guide cylinder. According to this, even when the movable core is tilted relative to the guide cylinder and the outer circumferential surface of the other end of the movable core is in contact with the inner circumferential surface of the guide cylinder, it is possible to prevent the tapered convex portion of the fixed core and the tapered recess of the movable core from colliding by line contact.

[0010] Furthermore, in the present invention, a projection may be provided on either the circumferential surface of the tapered convex portion of the fixed core or the circumferential surface of the tapered concave portion of the movable core, and the tapered concave portion of the movable core and the tapered convex portion of the fixed core may be configured to make point contact at this projection. With this configuration, even if the taper angle of the tapered convex portion of the fixed core is the same as the taper angle of the tapered concave portion of the movable core, or even if the movable core is not eccentric with respect to the fixed core by the amount of sliding clearance with respect to the guide cylinder, the tapered concave portion of the movable core and the tapered convex portion of the fixed core can be made to collide with the movable core and the fixed core in point contact.

[0011] Incidentally, in cases where a resin coating film is formed on the circumferential surface of the tapered convex portion of the fixed core or the circumferential surface of the tapered concave portion of the movable core, the resin coating film peels off due to collisions between the movable core and the fixed core, increasing the amount of wear dust generated. According to the present invention, since the collision area between the tapered concave portion of the movable core and the tapered convex portion of the fixed core is reduced, even if a resin coating film is formed on either the circumferential surface of the tapered convex portion of the fixed core or the circumferential surface of the tapered concave portion of the movable core, the generation of wear dust can be suppressed, which is advantageous.

[0012] A cross-sectional side view of a solenoid valve according to an embodiment of the present invention. (a) A cross-sectional side view showing the state in which the movable core and fixed core of a conventional solenoid valve collide. (b) A cross-sectional side view showing the state in which the movable core and fixed core of a solenoid valve of the first embodiment collide. (c) A cross-sectional side view showing the state in which the movable core and fixed core of a solenoid valve of the second embodiment collide. A cross-sectional side view showing the state in which the movable core and fixed core of a solenoid valve of the second embodiment, arranged in a position where their axes are perpendicular, collide.

[0013] Referring to Figure 1, 1 shows the valve housing of an embodiment of the solenoid valve of the present invention, which is interposed in gas piping, etc. Inside the valve housing 1, there is a valve seat 12 with a valve hole 11. The solenoid valve comprises a valve body 2 facing the valve seat 12 inside the valve housing 1, a movable core 3 connected to one end (left end in Figure 1) of the valve body 2, a guide cylinder 4 into which the movable core 3 is slidably inserted, a fixed core 5 positioned on the inner circumference of the other end of the guide cylinder 4 so as to face the other end (right end in Figure 1) of the movable core 3, a valve spring 6 interposed between the movable core 3 and the fixed core 5 and biasing the movable core 3 in a direction that isolates it from the fixed core 5, and an electromagnetic coil 7 arranged to surround the guide cylinder 4. The valve body 2 is a normally closed type, biased to the closed side by the valve spring 6 to close the valve hole 11. Hereinafter, the axial direction from the fixed core 5 toward the movable core 3 will be referred to as the axial direction one.

[0014] One end of the fixed core 5 (the left end in Figure 1) is provided with a tapered protrusion 51 that decreases in diameter as it moves toward one side in the axial direction. The other end of the movable core 3 is provided with a tapered recess 31 that also decreases in diameter as it moves toward one side in the axial direction. In order to improve the sliding properties of the tapered recess 31 of the movable core 3 with respect to the tapered protrusion 51 of the fixed core 5, a resin coating film such as fluororesin (not shown) is formed on one of the circumferential surfaces of the tapered protrusion 51 of the fixed core 5 and the tapered recess 31 of the movable core 3. When the electromagnetic coil 7 is energized and the movable core 3 is attracted to the fixed core 5 (i.e., the movable core 3 moves toward the other side in the axial direction), the tapered protrusion 51 of the fixed core 5 is inserted into the tapered recess 31 of the movable core 3, and the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 come into contact.

[0015] Here, the movable core 3 is manufactured to have a sliding clearance with respect to the guide cylinder 4, but due to dimensional variations, the sliding clearance may exceed the dimensional range expected in the design. In that case, as shown in Figure 2(a), if the tapered recess 31 of the movable core 3 and the tapered convex portion 51 of the fixed core 5 are formed to have the same taper angle, and the solenoid valve is positioned with its axis horizontal, the movable core 3 will always be eccentrically downward relative to the fixed core 5 by the amount of the sliding clearance with respect to the guide cylinder 4 due to its own weight. As a result, the upper side of the circumferential surface of the tapered recess 31 of the movable core 3 and the upper side of the circumferential surface of the tapered convex portion 51 of the fixed core 5 repeatedly collide with each other. This causes wear on the collision portion (line contact portion) between the movable core 3 and the fixed core 5, and wear particles are generated from the movable core 3 and the fixed core 5.

[0016] Therefore, in this embodiment, the movable core 3 is configured to be eccentrically positioned downward relative to the fixed core 5 by the amount of sliding clearance with respect to the guide cylinder 4, and the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 are configured to make point contact. Specifically, as shown in Figure 2(b), the taper angle of the tapered protrusion 51 of the fixed core 5 is configured to be smaller than the taper angle of the tapered recess 31 of the movable core 3.

[0017] According to the above embodiment, when the movable core 3 and the fixed core 5 collide, the movable core 3 is eccentrically positioned downward relative to the fixed core 5 by the amount of the sliding clearance with respect to the guide cylinder 4, and the tapered recess 31 of the movable core 3 and one axial end 51a of the tapered protrusion 51 of the fixed core 5 collide by point contact. As a result, the collision area between the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 is reduced. Consequently, the amount of wear dust generated by the wear of the movable core 3 and the fixed core 5 is reduced. Furthermore, because the collision area between the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 is reduced, the generation of wear dust can be suppressed even if a resin coating film such as fluororesin is formed on the circumferential surface of the tapered protrusion 51 of the fixed core 5 or the circumferential surface of the tapered recess 31 of the movable core 3. In this embodiment, the taper angle of the tapered protrusion 51 of the fixed core 5 is set to be smaller than the taper angle of the tapered recess 31 of the movable core 3. However, the taper angle of the tapered protrusion 51 of the fixed core 5 may be set to be larger than the taper angle of the tapered recess 31 of the movable core 3. In this case, when the movable core 3 and the fixed core 5 collide, the tapered recess 31 of the movable core 3 and the other axial end of the tapered protrusion 51 of the fixed core 5 collide by point contact, with the movable core 3 being eccentric with respect to the fixed core 5 by the amount of the sliding clearance with respect to the guide cylinder 4.

[0018] However, even if the taper angle of the tapered protrusion 51 of the fixed core 5 is set to be smaller than the taper angle of the tapered recess 31 of the movable core 3, depending on the angle difference between these taper angles, the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 may collide by line contact when the movable core 3 is tilted relative to the guide cylinder 4 and the outer circumferential surface of the other end of the movable core 3 is in contact with the inner circumferential surface of the guide cylinder 4. For this reason, the angle difference between the taper angle of the tapered protrusion 51 of the fixed core 5 and the taper angle of the tapered recess 31 of the movable core 3 is set so that the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 do not come into line contact when the movable core 3 is tilted relative to the guide cylinder 4 and the outer circumferential surface of the other end of the movable core 3 is in contact with the inner circumferential surface of the guide cylinder 4. The angle difference of these taper angles is set based on the length of the movable core 3 and the sliding clearance of the movable core 3 with respect to the guide cylinder 4. This prevents the tapered convex portion 51 of the fixed core 5 and the tapered concave portion 31 of the movable core 3 from colliding by line contact, even when the movable core 3 is tilted relative to the guide cylinder 4 and the outer circumferential surface of the other end of the movable core 3 is in contact with the inner circumferential surface of the guide cylinder 4.

[0019] Next, a second embodiment shown in Figure 2(c) will be described. The basic structure of the second embodiment is not particularly different from that of the first embodiment, and the same reference numerals are used for the same members and parts as in the first embodiment. The difference between the second embodiment and the first embodiment is that a projection 31a is provided on the circumferential surface of the tapered recess 31 of the movable core 3, and the tapered protrusion 51 of the fixed core 5 is configured to make point contact with the tapered recess 31 of the movable core 3 by the projection 31a. With this configuration, even if the taper angle of the tapered protrusion 51 of the fixed core 5 is the same as the taper angle of the tapered recess 31 of the movable core 3, the tapered recess 31 of the movable core 3 and the tapered protrusion 51 of the fixed core 5 can be made to collide by point contact when the movable core 3 and the fixed core 5 collide. Alternatively, a projection may be provided on the circumferential surface of the tapered convex portion 51 of the fixed core 5, so that the tapered concave portion 31 of the movable core 3 and the tapered convex portion 51 of the fixed core 5 come into contact by point contact due to this projection.

[0020] Although embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited thereto. In the above embodiments, a solenoid valve arranged in a position where the axis is horizontal was described as an example, but the present invention can be similarly applied to those arranged in a position where the axis is vertical. Figure 3 shows the state in which the movable core 3 and the fixed core 5 of a solenoid valve of the second embodiment, arranged in a position where the axis is vertical, collide. As shown in Figure 3, in this embodiment, even when the movable core 3 is not eccentric with respect to the fixed core 5 (by the amount of the sliding clearance with respect to the guide cylinder 4) when the movable core 3 and the fixed core 5 collide, the projection 31a can cause the tapered recess 31 of the movable core 3 and the tapered convex portion 51 of the fixed core 5 to collide by point contact.

[0021] Furthermore, although the above embodiment described an example in which a projection 31a is provided at one location on the circumferential surface of the tapered recess 31 of the movable core 3, it is desirable to provide three or more projections in the circumferential direction on the circumferential surface of the tapered recess 31 of the movable core 3. In the case where only one projection 31a is provided, depending on the direction in which the movable core 3 is eccentric, the projection 31a may prevent point contact between the tapered recess 31 of the movable core 3 and the tapered convex portion 51 of the fixed core 5 (for example, when the movable core 3 of a solenoid valve arranged in a position where its axis is perpendicular is eccentric with respect to the fixed core 5 by the amount of the sliding clearance with respect to the guide cylinder 4 in the direction of the base end of the projection 31a). For this reason, by providing three or more projections in the circumferential direction on the circumferential surface of the tapered recess 31 of the movable core 3, point contact can be made between the tapered recess 31 of the movable core 3 and the tapered convex portion 51 of the fixed core 5, regardless of the direction in which the movable core 3 is eccentric.

[0022] 1... Valve housing, 12... Valve seat, 2... Valve body, 3... Movable core, 31... Tapered recess, 31a... Projection, 4... Guide cylinder, 5... Fixed core, 51... Tapered protrusion, 6... Valve spring, 7... Electromagnetic coil.

Claims

1. An electromagnetic valve comprising a valve body facing a valve seat within a valve housing, a movable core connected to one end of the valve body, a guide cylinder into which the movable core is slidably inserted, a fixed core positioned on the inner circumference of the other end of the guide cylinder so as to face the other end of the movable core, a valve spring that biases the movable core in a direction that isolates it from the fixed core, and an electromagnetic coil positioned to surround the guide cylinder, wherein the axial direction from the fixed core toward the movable core is considered as one axial direction, and one end of the fixed core facing the other end of the movable core is provided with a tapered convex portion that decreases in diameter as it moves toward one axial direction, and the other end of the movable core is provided with a tapered concave portion that decreases in diameter as it moves toward one axial direction, and when the movable core is attracted to the fixed core, the tapered convex portion of the fixed core is inserted into the tapered concave portion of the movable core, and the tapered concave portion of the movable core and the tapered convex portion of the fixed core come into contact, A solenoid valve characterized in that the tapered recess of the movable core and the tapered protrusion of the fixed core make point contact, or the tapered recess of the movable core and the tapered protrusion of the fixed core make point contact when the movable core is eccentric with respect to the fixed core by the amount of sliding clearance with respect to the guide cylinder.

2. A solenoid valve according to claim 1, characterized in that the taper angle of the tapered recess of the movable core and the taper angle of the tapered convex portion of the fixed core are different angles.

3. The solenoid valve according to claim 2, characterized in that the taper angle of the tapered convex portion of the fixed iron core is smaller than the taper angle of the tapered concave portion of the movable iron core.

4. A solenoid valve according to claim 2 or 3, characterized in that the angle difference between the taper angle of the tapered convex portion of the fixed core and the taper angle of the tapered concave portion of the movable core is set so that even when the movable core is inclined with respect to the guide cylinder and the outer circumferential surface of the other end of the movable core is in contact with the inner circumferential surface of the guide cylinder, the tapered concave portion of the movable core and the tapered convex portion of the fixed core do not make line contact.

5. The solenoid valve according to claim 1, characterized in that a projection is provided on either the circumferential surface of the tapered convex portion of the fixed iron core or the circumferential surface of the tapered concave portion of the movable iron core, and the tapered concave portion of the movable iron core and the tapered convex portion of the fixed iron core make point contact at this projection.

6. The solenoid valve according to claim 1, characterized in that a resin coating film is formed on either the circumferential surface of the tapered convex portion of the fixed iron core or the circumferential surface of the tapered concave portion of the movable iron core.

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