JP2859838B2 - solenoid valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve, and more particularly to a structure near a valve seat.

[0002]

2. Description of the Related Art Conventionally, a fluid flow path is switched by a rubber seal material which moves integrally with a plunger coming into and out of contact with a valve seat formed on an inner wall surface of a metal or resin casing. An electromagnetic valve configured as described above is known.

[0003] When power is not supplied to this type of electromagnetic valve, the rubber seal material is normally brought into close contact with the valve seat by being urged by a spring or the like. However, if such a non-energized state is maintained for a long period of time, the rubber seal material adheres to the valve seat portion, and there is a problem that the fluid flow path is not opened even when the electric current is applied. It has also been known that the higher the temperature of the atmosphere in which the solenoid valve is used, the shorter the period in which the rubber seal material is fixed. Further, although the rubber seal material is made of hard rubber, it is relatively brittle, so that abrasion and cracks occur at an early stage especially in an electromagnetic valve in which the rubber seal material and the valve seat frequently come and go. .

For this reason, conventionally, as shown in FIG. 6, a measure has been taken to cover the entire inner wall surface of a casing 22 including a valve seat portion 21 with a fluororesin layer 23. In other words, by interposing the non-adhesive fluororesin layer 23 between the valve seat portion 21 and the rubber seal material 24, it is possible to avoid sticking of the two members 21 and 24 and reduce wear and cracks of the rubber seal material 24. Was.

[0005]

However, since the fluororesin layer 23 has poor adhesion to metal or the like, the portion of the valve seat 21 where the rubber seal material 24 frequently comes into contact (that is, the valve seat tip 21a). Fluororesin layer 23 to protect
Tends to peel off particularly early. When such peeling occurs, the valve seat portion 21 is exposed, and it is no longer possible to avoid sticking and reduce wear and cracks. Accordingly, there has been a strong demand for realizing a solenoid valve with higher durability by making some improvements.

In many cases, the valve seat tip 21a has an acute angle, and it is difficult to form a fluororesin layer 24 having a uniform thickness and a small surface roughness thereon. Therefore, the fluid is liable to leak from the seal portion inevitably, and it has not been possible to realize an electromagnetic valve such as a vacuum break valve that requires high sealing performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electromagnetic valve in which a rubber seal material is hardly fixed to a valve seat, and in which the rubber seal material is hardly worn or cracked. It is in.

A second object of the present invention is to provide a solenoid valve capable of eliminating sticking, abrasion, and cracks of the rubber sealing material without deteriorating the sealing performance.

[0009]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a rubber seal member which moves integrally with a plunger is provided on a valve seat formed on an inner wall surface of a casing. In the solenoid valve configured to perform the switching of the fluid flow path by contacting and separating, the composite plating layer in which the fluororesin particles are dispersed in the Ni-containing metal matrix is formed on the inner wall surface of the casing. The gist is a solenoid valve characterized by the following.

[0010] According to a second aspect of the present invention, in the first aspect, the composite plating layer is formed only on the valve seat portion on the inner wall surface of the casing. The invention according to claim 3 is the invention according to claim 1 or 2, wherein
The metal matrix was a Ni-P (nickel-phosphorus) matrix, and the fluororesin particles were PTFE (polytetrafluoroethylene) particles.

According to a fourth aspect of the present invention, in the third aspect, the content of the PTFE particles in the composite plating layer is 10% by volume to 50% by volume. According to a fifth aspect of the present invention, in the third or fourth aspect, the thickness of the composite plating layer is 5 μm to 10 μm.

The "action" of the present invention will be described below. According to the first to fifth aspects of the present invention, since the composite plating layer is formed on the inner wall surface of the casing, direct contact between the valve seat portion and the rubber seal material is prevented. Is reduced.

Further, since the composite plating layer is obtained by dispersing fluororesin particles in a Ni-containing metal matrix, the properties of Ni, which is hard and high in adhesion, and the properties of fluororesin, which is non-adhesive, are used. And have.

That is, the property derived from the fluororesin prevents the rubber seal material from sticking to the valve seat portion, and the property derived from Ni prevents the composite plating layer from peeling off early. Therefore, the wear and cracks can be reduced for a long time, and the durability of the solenoid valve is improved.

Further, since the composite plating layer is formed by a plating method, the thickness of the composite plating layer is uniform and the surface roughness is small as compared with a conventional layer made of a fluororesin alone. For this reason, the fluid does not leak from the sealing portion, and the sealing performance does not decrease.

According to the second aspect of the present invention, since the composite plating layer is formed only on the valve seat portion of the inner wall surface of the casing, the composite plating layer is formed, for example, over the entire inner wall surface of the casing. As a result, it is possible to reliably prevent the cost from increasing.

According to the fourth aspect of the invention, the content of the PTFE particles in the composite plating layer is from 10% by volume to 50% by volume.
Since the content is% by volume, the occurrence of sticking of the rubber sealing material can be reduced without making the production difficult and increasing the cost.

According to the fifth aspect of the present invention, since the thickness of the composite plating layer is 5 μm to 10 μm, the occurrence of sticking of the rubber seal material can be reliably avoided without increasing the cost.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a solenoid valve will be described below in detail with reference to FIGS.

As shown in FIG. 1, the solenoid valve 11 of the present embodiment is constituted by two parts, a solenoid 12 and a valve section 13. A fluid flow path 14 is formed inside a metal casing 13a constituting the valve section 13. In the fluid flow path 14, a rubber seal material 15 as a valve driven by the solenoid 12 is provided movably between a pair of opposed valve seats 16 and 17.

A coil 2 is wound around the outer peripheral surface of the bobbin 1 constituting the solenoid 12. A cylindrical core (fixed iron core) 4 is fitted in a through hole 1 a of the bobbin 1 via a yoke 3. The upper end of the sliding cylinder 5 is fitted to the lower end of the core 4. In such a sliding cylinder 5, a plunger (movable iron core) 6 having a cylindrical shape is slidably provided in the vertical direction. The core 4 and the plunger 6 are both formed using a ferromagnetic material such as an iron alloy.

A coil spring 7 is disposed between the contact surface (lower end surface) 4a on the core 4 side and the contact surface (upper end surface) 6a on the plunger 6 side. The upper end of the coil spring 7 is in contact with the inner bottom surface of the concave portion 4b formed at the center of the lower end surface 4a of the core 4. On the other hand, the lower end of the coil spring 7 is in contact with the inner bottom surface of a spring hole 6b formed in the center of the upper end surface 6a of the plunger 6. For this reason,
The urging force of the coil spring 7 always acts in a direction to separate the core 4 and the plunger 6 from each other. Therefore, when the coil 2 is not energized, the lower end surface 4 of the core 4
A constant distance is maintained between the upper end surface 6a and the upper end surface 6a of the plunger 6 (see FIG. 1). Note that, at this time, the rubber seal material 15 maintains a state in contact with the lower valve seat portion 17. Here, when the coil 2 is energized, a closed magnetic path orbiting around the yoke 3, the core 4, and the plunger 6 is formed. Then, the plunger 6 is attracted to the core 4 against the urging force of the coil spring 7, and the upper end surface 6 a of the plunger 6 collides with the lower end surface 4 a of the core 4. At this time, the rubber seal material 15 comes into contact with the upper valve seat portion 16, and as a result, the direction in which the fluid flows is switched.

As conceptually shown in FIG. 2, a so-called self-lubricating composite plating layer 18 is formed on both valve seats 16 and 17 on the inner wall surface of the casing 13a. This composite plating layer 18 is obtained by dispersing fluororesin particles 18b in a Ni-containing metal matrix 18a. However, the composite plating layer 18 is not formed in portions other than the valve seat portions 16 and 17, and the inner metal wall surface is exposed.

In this embodiment, the Ni-containing metal matrix 18 is used.
The Ni-P matrix 18a is selected as a,
And the PTFE particles 18 as the fluororesin particles 18b.
b has been selected. Note that the composite plating layer 18
Both the electrolytic plating method and the electroless plating method can be formed by a technique. However, the electroless plating method is preferable because the film thickness becomes uniform.

PTFE particles 1 in composite plating layer 18
The content of 8b is preferably from 10% by volume to 50% by volume, and particularly preferably from 20% by volume to 40% by volume. When the content is more than 50% by volume, not only a problem in production that plating is hardly adhered to a surface to be plated occurs, but also a cost increase is caused. Further, the strength of the composite plating layer 18 itself is reduced by an amount corresponding to the decrease in the metal content. On the other hand, when the content is 10
If the amount is less than the volume%, the effect of reducing the fixing strength of the rubber seal material 15 (described later) cannot be sufficiently obtained.

The thickness of the composite plating layer 18 is 5 μm to 20 μm.
μm, and particularly preferably 5 μm to 10 μm. If the composite plating layer 18 is too thin, the aforementioned effect of reducing the fixing strength cannot be sufficiently obtained, and the film thickness may be non-uniform. On the other hand, the composite plating layer 18
Even if the thickness is made thicker than necessary, the expected effect is not so large, which leads to higher costs.

Next, various comparative tests for the solenoid valve 11 of the present embodiment will be described. The line graph in FIG.
It shows the results of a valve seat impact test. In the graph, the vertical axis represents the depth (μm) of cracks generated in the rubber seal material 15, and the horizontal axis represents the number of operations (ie, the number of times the rubber seal 15 collides with the valve seats 16 and 17). The squares plotted in the graph are the values obtained by measuring the cracks of the solenoid valve 11 of the present embodiment, and the squares represent the comparative examples (the composite plating layer 18 was not formed and the valve seats 16 and 1 were not formed).
7 is exposed) is a value obtained by measuring the crack of the solenoid valve. In the solenoid valve 11 of the embodiment, the thickness of the composite plating layer 18 is set to 10 μm, and the content of the PTFE particles 18b is set to 30% by volume.

As a result, when the crack depth is compared when the number of operations is the same, the solenoid valve 11 of the present embodiment is clearly shallower. Therefore, it can be seen that the configuration like the electromagnetic valve 11 of the present embodiment can surely reduce the occurrence of cracks.

The bar graph in FIG. 4 shows the results of the adhesion test. In the graph, the vertical axis indicates the fixing strength (kg
f / cm ² ). When the rubber seal material 15 is pressed against the valve seats 16 and 17 at a predetermined temperature,
It means the magnitude of the force required to peel off the rubber seal material 15. Here, four test sections are set. In the first test section, the composite plating layer 18 (thickness 1) was formed on the valve seats 16 and 17.
0 μm, the content of PTFE particles 18b is 30% by volume), and a rubber seal material 15 made of nitrile rubber is used. In the second test section, a similar composite plating layer 18 was formed, and a rubber seal material 15 made of fluoro rubber was used. The third test section is the composite plating layer 1
No. 8 and a rubber seal material 1 made of nitrile rubber
5 is used. In the fourth test section, the composite plating layer 18 was not formed, and the rubber seal material 15 made of fluoro rubber was used. That is, the first and second test sections are embodiments, and the third and fourth test sections are comparative examples. Here, aluminum was selected as the material of the valve seat portions 16 and 17 (that is, the material of the casing 13a). The surface pressure was set to 20 kgf / cm ² , the temperature was set to 70 ° C., and the pressing time was set to 24 hours. The number of samples in one test plot was three.

As a result, no fixation of the rubber sealing material 15 was observed in the test sections 1 and 2, whereas fixation was observed in the test sections 3 and 4. In addition, it was found that the rubber sealing material 15 made of fluororubber has a higher fixing strength than the rubber sealing material 15 made of nitrile rubber. As is clear from the above description, it is understood that the configuration of the present embodiment can solve the problem of sticking of the rubber seal material 15.

The line graph of FIG. 5 shows that the PTFE particles 18
It shows the change in the fixing strength when the content of b (volume%) is changed. The vertical axis of the graph is the bond strength (kgf / cm
² ), and the horizontal axis represents the content (% by volume) of the PTFE particles 18b. Here, the valve seat portion 16,
Brass (# 1500 polishing) was selected as the material of No. 17, and a rubber seal material 15 made of NBR was selected. Further, the thickness of the composite plating layer 18 was set to 10 μm. Further, the surface pressure is 20 kgf / cm ² , the temperature is 70 ° C., and the pressing time is 96
Each time was set. The content of the PTFE particles 18b was changed by 10% by volume such as "0, 10, 20, 30, 40, 50". The data obtained is plotted with ■.

As a result, the fixing strength at 0% by volume is about 1.8 kgf / cm ² , whereas the fixing strength at 10% by volume is about 0.3 kgf / cm ² , which is several minutes. It turned out to be one. Furthermore, it was found that when the content was set to 20% by volume or more, the fixing strength was 0 kgf / cm ² , and no fixing occurred.

In the following, the characteristic effects of this embodiment will be listed. (A) According to the present embodiment, by forming the composite plating layer 18 on the valve seat portions 16 and 17 on the inner wall surface of the casing 13a, direct contact between the valve seat portions 16 and 17 and the rubber seal material 15 is prevented. Has been prevented. For this reason, wear and cracks of the rubber seal material 15 can be reduced.

Further, since the composite plating layer 18 is obtained by dispersing the fluororesin particles 18b in the Ni-containing metal matrix 18a, the property of Ni, which is hard and high in adhesion, and the property of fluorine, which is non-adhesive, are used. Has the properties of resin. That is, sticking of the rubber seal material 15 to the valve seats 16 and 17 is prevented by the property derived from the fluororesin, and early peeling of the composite plating layer 18 is prevented by the property derived from Ni. Therefore, the wear and cracks can be reduced over a long period of time,
Thus, the durability of the solenoid valve 11 can be improved.

(B) According to the present embodiment, since the composite plating layer 18 is formed by a plating method, the thickness of the composite plating layer 18 is uniform and the surface roughness is smaller than that of a conventional layer made of a fluororesin alone. Also small. For this reason, even if the composite plating layer 18 is formed, fluid does not leak from the sealed portion, and the sealing performance does not decrease.
Therefore, it is possible to sufficiently cope with applications requiring high sealing properties, such as a vacuum break valve. In addition, since the composite plating layer 18 is formed by electroless plating, the uniformity of the film thickness is particularly excellent.

(C) According to the present embodiment, the casing 1
The composite plating layer 18 is formed only on the valve seat portions 16 and 17 of the inner wall surface of the portion 3a. Therefore, for example, the casing 1
As compared with the case where it is formed over the entire inner wall surface of 3a, it is possible to surely prevent cost increase. This is because a small amount of the plating solution or the like is required.

The present invention is limited to the above embodiment.
No, it is possible to change to the following form, for example
Noh. (1) As Ni-containing metal matrix 18a
Is in addition to the Ni-P matrix exemplified in the embodiment.
Are also, for example, Ni matrix, Ni-Co matrix, N
i-Fe matrix, Ni-Mn matrix, Ni-B
It is acceptable to use a matrix or the like. Again
Besides these, Cu matrix, Co matrix, Fe matrix
It is acceptable to use a matrix or the like.

(2) PTF as fluororesin particles 18b
It is acceptable to use a resin other than the E particles 18b, and further use fluorinated graphite (CF) _n . (3) Not only the formation of the composite plating layer 18 by the electroless plating method but also the formation of the composite plating layer 18 by the electrolytic plating method can be permitted.

(4) It is permissible to form the composite plating layer 18 not only on the valve seats 16 and 17 but also on the entire inner wall surface of the casing 13a and further on the entire casing 13a including the outer wall surface. However, in order to reduce costs,
It can be said that it is preferable to form the composite plating layer 18 only on necessary portions as in the embodiment.

(5) The present invention is not limited to being applied to only the electromagnetic valve 11 in which the rubber seal material 15 as the valve body and the plunger 6 are separate bodies as in the embodiment. Therefore, the present invention can be similarly applied to, for example, the one in which the rubber seal material 15 is joined to the tip of the plunger 6, that is, the one in which the two 6, 15 are integrated.

Here, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) In an electromagnetic valve configured to switch a fluid flow path by a rubber seal material moving integrally with a plunger coming into and out of contact with a valve seat formed on an inner wall surface of a casing. An electromagnetic valve, wherein a lubricating dispersed plating layer is formed on an inner wall surface of the casing.

(2) In the technical idea (1), the self-lubricating dispersed plating layer is formed by fluorinated graphite and fluororesin particles in a metal matrix containing one kind selected from Cu, Fe, Co and Ni. Characterized in that at least one of them is dispersed.

(3) In any one of claims 1 to 5,
The composite plating layer is formed by electroless plating. With this configuration, the thickness of the composite plating layer can be made uniform as compared with the case of electrolytic plating, so that the sealing property can be further improved.

The technical terms used in the present specification are defined as follows. “Composite plating layer: refers to a plating layer obtained when plating is deposited in a state in which hardly soluble fine particles are dispersed in an electroplating bath or an electroless plating bath.”

[0045]

As described above in detail, according to the first to fifth aspects of the present invention, an electromagnetic valve in which a rubber seal material is hardly fixed to a valve seat portion, and in which the rubber seal material is hardly worn or cracked, It can be provided without a decrease in sealing performance.

According to the second aspect of the present invention, it is possible to reliably prevent an increase in cost as compared with the case where the composite plating layer is formed over the entire inner wall surface of the casing. According to the fourth aspect of the present invention, it is possible to reduce the occurrence of sticking of the rubber seal material without making manufacturing difficult and increasing costs. According to the invention described in claim 5,
In addition to the effects of the fourth aspect of the present invention, the occurrence of sticking of the rubber seal material can be reliably avoided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a solenoid valve according to an embodiment.

FIG. 2 is a partially enlarged sectional view conceptually showing a valve seat portion of the solenoid valve.

FIG. 3 is a line graph showing the results of a valve seat impact test.

FIG. 4 is a bar graph showing the results of an adhesion test.

FIG. 5 is a line graph showing a change in fixation strength when the content of PTFE particles is changed.

FIG. 6 is a partially enlarged sectional view showing a valve seat in a conventional solenoid valve.

[Explanation of symbols]

4 fluid path, 6 plunger, 11 solenoid valve, 13a
... Casing, 15 ... Rubber sealing material, 16, 17 ... Valve seat, 18 ... Composite plating layer, 18a ... Ni-P matrix as Ni-containing metal matrix, 18b ... PTFE particles as fluororesin particles.

Claims (5)

(57) [Claims] An electromagnetic valve configured to switch a fluid flow path when a rubber seal material moving integrally with a plunger comes into contact with or separates from a valve seat formed on an inner wall surface of a casing. An electromagnetic valve, wherein a composite plating layer in which fluorine resin particles are dispersed in a Ni-containing metal matrix is formed on an inner wall surface of the casing. 2. The solenoid valve according to claim 1, wherein the composite plating layer is formed only on the valve seat portion on the inner wall surface of the casing. 3. The solenoid valve according to claim 1, wherein the Ni-containing metal matrix is a Ni-P matrix, and the fluororesin particles are PTFE particles. 4. The solenoid valve according to claim 3, wherein the content of the PTFE particles in the composite plating layer is 10% by volume to 50% by volume. 5. The composite plating layer has a thickness of 5 μm to 10 μm.
The solenoid valve according to claim 3, wherein the diameter is μm.