Electromagnetic valve

Abstract

To maintain the characteristics of a solenoid valve constant over a long period.SOLUTION: And a main valve including a second valve seat provided with a second valve port and a second valve body (valve body 22) to be brought into contact with and separated from the second valve seat, the second valve body being brought into contact with and separated from the second valve seat by a pressure difference between a pressure in an upstream-side space in a flow passage of a passage control target fluid and a pressure in a pressure chamber with which the first valve port communicates. The cleaning pin (needle portion 24h) includes a metallic pin main body (main body portion 41) and a resin-made cylindrical body (covering portion 42) covering at least a front end portion of the pin main body in a longitudinal direction of the pin main body. The small hole (small hole 25a) allows the upstream space and the pressure chamber to communicate with each other.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic valve in which a valve body of a main valve is moved toward or away from a valve seat depending on the pressure difference between the pressure in an upstream space in the flow path of a fluid to be controlled and the pressure in a pressure chamber connected to a valve port of a pilot valve, and a small hole is opened in the valve body through which a cleaning pin is inserted. [Background technology]

[0002] As an example of this type of solenoid valve, the applicant has disclosed in the following patent documents a solenoid valve that is equipped with a main valve and a pilot valve and is configured to restrict / allow the passage of tap water, which is an example of a fluid whose passage is to be controlled.

[0003] In the solenoid valve disclosed by the applicant, when a small hole (hereinafter referred to as a "valve port" to distinguish it from a small hole opened in the valve body of the main valve, which will be described later) that connects the downstream space in the flow path of tap water with the pressure chamber is closed by the valve body of the pilot valve, the pressure in the upstream space in the flow path of tap water and the pressure in the pressure chamber become approximately equal, the main valve is in a closed state, and the passage of tap water is restricted. Also, when the valve body of the pilot valve is separated from the above-mentioned valve port, the tap water in the pressure chamber flows out into the downstream space through the valve port, the pressure in the pressure chamber becomes lower than the pressure in the upstream space, the main valve is shifted to an open state, and the passage of tap water is permitted.

[0004] In this case, in the solenoid valve disclosed by the applicant, a small hole that allows tap water to flow from the upstream space into the pressure chamber is opened in the valve body (main body and valve membrane), and one end of a spring that urges the valve body of the main valve toward the valve port is inserted into the small hole, so that when the valve body opens and closes, the one end of the spring functions as a "cleaning pin" to clean the inside of the small hole. This prevents the solenoid valve disclosed by the applicant from becoming clogged, and makes it possible to maintain a state in which tap water can flow smoothly from the upstream space into the pressure chamber via the small hole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-040309 A (pages 5-10, figures 1-7) Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-described solenoid valve disclosed by the applicant has the following problems that need to be improved.

[0007] Specifically, the solenoid valve disclosed by the applicant employs a configuration in which one end of a spring is inserted as a cleaning pin into a small hole in the valve disc of the main valve, so that the cleaning pin cleans the inside of the small hole when the valve disc is opened or closed. In this case, the spring in this solenoid valve is formed by bending a metal wire such as stainless steel, and one end of the spring (the portion that functions as the cleaning pin) is also made of metal wire, just like the spring body. By employing such a configuration, it is possible to provide a cleaning pin that has sufficient strength and will not be damaged or deformed due to deterioration even with long-term use, making it possible to maintain a state in which the inside of the small hole can be suitably cleaned for a long period of time.

[0008] On the other hand, in the solenoid valve disclosed by the applicant, the valve body (main body and valve membrane) with the small hole is made of resin or rubber, making the resin valve body more susceptible to wear than a metal cleaning pin. Therefore, in this solenoid valve, the main valve is repeatedly opened and closed over a long period of use, and each time the inner surface of the small hole slides against the outer circumferential surface of the cleaning pin, causing wear on the inner surface of the small hole (valve body), which can change the opening shape and opening area of ​​the small hole. In this case, in the solenoid valve disclosed by the applicant, the opening shape of the small hole and the cross-sectional shape of the cleaning pin are both circular. Furthermore, in this type of solenoid valve, the opening area of ​​the small hole and the cross-sectional area of ​​the cleaning pin are each specified so that an appropriate amount of tap water can flow from the upstream space into the pressure chamber under the expected usage environment.

[0009] However, as described above, when the opening shape and opening area of ​​the small hole change due to long-term use, the flow rate of tap water that can pass through the gap between the inner surface of the small hole and the cleaning pin per unit time changes. As a result, the valve characteristics, such as the valve opening characteristics (e.g., the time required to open the valve) and the valve closing characteristics (e.g., the time required to close the valve), differ from the initial values ​​(design values). Therefore, it is desirable to improve this point.

[0010] The present invention has been made in view of the above-mentioned problems to be solved, and has as its main object to provide a solenoid valve whose characteristics can be maintained constant for a long period of time. [Means for solving the problem]

[0011] In order to achieve the above object, the solenoid valve described in claim 1 is a solenoid valve comprising: a first valve seat having a first valve port, a first valve body that can be moved toward and away from the first valve seat, and a pilot valve having an actuator that moves the first valve body toward and away from the first valve seat; and a main valve having a second valve seat having a second valve port and a second valve body that can be moved toward and away from the second valve seat, wherein the second valve body is moved toward and away from the second valve seat due to the pressure difference between the pressure in an upstream space in a flow path of a fluid to be passed through and the pressure in a pressure chamber that is connected to the first valve port. The main valve has a small hole in the second valve body that connects the upstream space with the pressure chamber, and is provided with a cleaning pin that is inserted into the small hole. The cleaning pin comprises a metal pin body and a resin cylindrical body that covers at least a longitudinal tip end portion of the pin body.

[0012] In addition, the solenoid valve described in claim 2 is the solenoid valve described in claim 1, wherein the main valve is formed such that the opening shape of the small hole and the cross-sectional shape of the cylindrical body in the cleaning pin are different.

[0013] Furthermore, a third aspect of the present invention provides a solenoid valve according to the first or second aspect of the present invention, wherein the main valve has a circular opening shape of the small hole and a non-circular cross section of the cylindrical body. [Effects of the Invention]

[0014] The solenoid valve described in claim 1 is provided with a main valve in which a second valve body is moved toward or away from a second valve seat depending on the pressure difference between the pressure in an upstream space in the flow path of the fluid to be controlled and the pressure in a pressure chamber connected to a first valve port of the pilot valve, and the main valve has a small hole in the second valve body that connects the upstream space with the pressure chamber, and a cleaning pin inserted into the small hole, and the cleaning pin has a metal pin body and a resin cylindrical body that covers at least the tip end portion of the pin body in the longitudinal direction.

[0015] Therefore, according to the solenoid valve of claim 1, even if the second valve body is caused to slide relative to the cleaning pin while the inner surface of the small hole is in contact with the cleaning pin during cleaning operation (during opening and closing of the main valve), there is no significant difference in the likelihood of wear between the inner surface of the small hole and the cylindrical body of the cleaning pin, so it is possible to avoid significant abrasion of the inner surface of the small hole due to sliding with the cleaning pin (cylindrical body).This makes it possible to prevent the opening shape and opening area of ​​the small hole from changing in a short period of time, so the characteristics of the solenoid valve can be maintained constant over a long period of time.

[0016] In the solenoid valve of claim 2, the second valve body and the cleaning pin are formed so that the opening shape of the small hole and the cross-sectional shape of the cylindrical body of the cleaning pin are different. Also, in the solenoid valve of claim 3, the opening shape of the small hole is circular and the cross-sectional shape of the cylindrical body is non-circular. Therefore, according to the solenoid valves of claims 2 and 3, it is possible to sufficiently ensure the effective passage area of ​​the fluid to be controlled passing between the inner surface of the small hole and the cleaning pin (cylindrical body), while suitably preventing the cleaning pin from moving wildly inside the small hole during cleaning operation (when the main valve is opened or closed), and it is possible to more suitably prevent large abrasions from occurring on the inner surface of the small hole. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is an external perspective view of a solenoid valve 1. [Figure 2] 2 is another external perspective view of the solenoid valve 1. FIG. [Figure 3] FIG. 2 is a cross-sectional view of the solenoid valve 1. [Figure 4] FIG. 2 is a perspective view of the appearance of a valve body 22 and a spring 25. [Figure 5] 10 is another external perspective view of the valve body 22 and the spring 25. FIG. [Figure 6] FIG. 2 is an exploded perspective view of a valve body 22 and a spring 25. [Figure 7] 2 is a perspective view of the appearance of a needle portion 25a of a spring 25. FIG. [Figure 8]3 is a cross-sectional view of a valve body 22 and a spring 25. FIG. [Figure 9] 2 is a cross-sectional view of a valve body 22a and a spring 26. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a solenoid valve according to the present invention will be described with reference to the accompanying drawings.

[0019] 1 to 3 is a "pilot solenoid valve" which is an example of a "solenoid valve", and is arranged in a supply pipe for tap water which is an example of a "fluid whose passage is to be controlled", and is configured to allow / restrict the passage of tap water from an inlet Hi to an outlet Ho. As shown in Fig. 3, this solenoid valve 1 has a main valve 2 and a pilot valve 3 formed in a resin body 10, and a filter 4 is arranged at the inlet Hi.

[0020] The main valve 2 is a "diaphragm valve" which is an example of a "main valve" and, as shown in Fig. 3, includes a valve seat 21, a valve element 22, and a spring 25. The main valve 2 is configured so that the valve element 22 moves toward and away from the valve seat 21 depending on the pressure difference between the pressure in the pressure chamber Sp (an example of a "pressure chamber") and the pressure in an upstream space Si (a space communicated with an inlet Hi provided in the main body 11 of the body 10: an example of an "upstream space") located upstream in the flow path of tap water.

[0021] The valve seat 21 is an example of a "second valve seat" and is formed in the main body 11 of the body 10. Specifically, in the solenoid valve 1 of this example, a valve port 21h (an example of a "second valve port") for discharging tap water from the upstream space Si to a downstream space So (a space communicated with an outlet Ho provided in the main body 11: an example of a "downstream space") located downstream in the flow path of the tap water) is formed in the main body 11, thereby configuring the valve seat 21 of the main valve 2.

[0022] The valve body 22 is an example of a "second valve body" and, as shown in Figures 4 to 6, includes a valve membrane portion 23 and a plate-like portion 24. The valve membrane portion 23 is formed in a circular shallow dish shape from a material (e.g., silicone rubber) having a lower elastic modulus than the material of the plate-like portion 24, and has insertion holes 23ha and 23hb formed therein. As shown in Figure 3, the plate-like portion 24 is fixed to the body 10 such that its outer edge is sandwiched between the main body 11 and the guide member 12. The plate-like portion 24 is formed in a circular shallow dish shape from a material (e.g., PPS (Poly Phenylene Sulfide Resin)) having a higher elastic modulus than the material of the valve membrane portion 23 so as to function as a "base (valve membrane holder)" that prevents unintended deformation of the valve membrane portion 23 by being integrated with the valve membrane portion 23, and also functions as a "spring abutment" against which one end of the spring 25 abuts.

[0023] 6, the plate-shaped portion 24 is provided with a valve port 31h that functions as the "first valve port" in the pilot valve 3, and a small hole 24h (a bleed hole: an example of a "small hole that communicates between the upstream space Si and the pressure chamber") that allows tap water to flow from the upstream space Si into the pressure chamber Sp. In this case, in the solenoid valve 1 (main valve 2) of this example, as shown in FIGS. 3 to 5, the valve port 31h is formed in the plate-shaped portion 24 at a position opposite to the valve seat 31 that functions as the "first valve seat") inserted into the insertion hole 23ha of the valve membrane portion 23, and the small hole 24h is formed in the plate-shaped portion 24 inserted into the insertion hole 23hb of the valve membrane portion 23, so that the valve membrane portion 23 and the plate-shaped portion 24 are integrated to form the valve body 22.

[0024] With regard to the two components that make up the valve element 22, the valve membrane portion 23 must be made of a resin or rubber that is capable of elastic deformation so that it can function as a diaphragm valve. As for the plate-shaped portion 24, it cannot be made of a heavy material as this would hinder the valve element 22 from moving towards or away from the valve seat 21, and in addition, since the special shape of the valve seat 31 (valve opening 31h) and the like must be formed inexpensively, this portion must also be made of a lightweight resin material that is easy to mold.

[0025] 3, the spring 25 is accommodated in the body 10 (in the pressure chamber Sp) with one end (the lower end in the figure) of the coiled portion abutting against the valve element 22 (the plate-shaped portion 24) and the other end (the upper end in the figure) of the coiled portion abutting against the guide member 12, thereby being able to urge the valve element 22 toward the valve seat 21. Also, as shown in Figures 3 to 6, the solenoid valve 1 (main valve 2) of this example has a needle portion 25a (an example of a "cleaning pin") provided continuous with the coiled portion of the spring 25, and this needle portion 25a is inserted into a small hole 24h of the valve element 22, so that the small hole 24h is cleaned by the needle portion 25a as the valve element 22 moves toward or away from the valve seat 21.

[0026] In this case, as shown in FIGS. 6 and 7 , the solenoid valve 1 (main valve 2) of this example includes a main body 41 (an example of a “metal pin body”) integrally formed with (continuously formed with) the coiled portion of the spring 25 by bending a metal wire such as stainless steel, and a resin covering 42 (an example of a “resin cylinder covering at least a longitudinal portion of the pin body”) fixed to the main body 41 so as to cover the tip of the main body 41. Note that in the solenoid valve 1 (main valve 2) of this example, the covering 42 is formed of PPS (Poly Phenylene Sulfide Resin), the same material as the plate-like portion 24 (the member in which the small hole 24h is formed). As a result, the inner surface of the small hole 24h in the plate-like portion 24 and the covering 42 in the needle portion 25a have similar wear characteristics.

[0027] 8, in the solenoid valve 1 (main valve 2) of this example, the opening shape of the aforementioned small hole 24h is circular with an inner diameter L22 of approximately 1.1 mm, while the cross-sectional shape of the covering portion 42 of the needle portion 25a is non-circular (for example, gear-shaped) with a minimum outer diameter L42a of approximately 0.8 mm and a maximum outer diameter L42b of approximately 0.9 mm, and they are integrated together (this is an example of a configuration in which the opening shape of the small hole and the cross-sectional shape of the cylindrical body of the cleaning pin are different). As a result, in the solenoid valve 1 (main valve 2) of this example, when the needle portion 25a is inserted through the small hole 24h with their centers aligned, a gap of approximately 0.15 mm is formed between the minimum diameter portion of the covering portion 42 and the inner surface of the small hole 24h, and a gap of approximately 0.10 mm is formed between the maximum diameter portion of the covering portion 42 and the inner surface of the small hole 24h, allowing tap water to flow from the upstream space Si into the pressure chamber Sp through these gaps.

[0028] In this example, the solenoid valve 1 (main valve 2) is configured with a spline gear-shaped covering portion 42 having six convex portions (i.e., six concave portions) as an example of a "cylinder having a non-circular cross-sectional shape," but the cross-sectional shape of the "cylinder" can be any non-circular shape, and as an example, the number of convex portions (concave portions) can be a non-circular shape other than six (not shown). In this case, by setting the number of convex portions (the number of portions with small gaps between them and the inner surface of the "small hole") to three or more and by arranging the convex portions evenly in the circumferential direction, it is possible to suitably prevent the "movement of the cleaning pin inside the small hole," which will be described later.

[0029] Furthermore, the needle portion 25a in the solenoid valve 1 (main valve 2) in this example is configured with a cap-shaped (cylindrical with one end closed and the other end open) covering portion 42, but instead of the covering portion 42, a "cylinder" formed in a straw shape (cylindrical with both ends open) can be attached to the tip side of the "main body" to form a "cleaning pin" (the tip of the "main body" is exposed from the "cylinder") (not shown).

[0030] In this case, in the needle portion 25a of this example, as an example, the covering portion 42 is present at the portion facing the inner surface of the small hole 24h when the main valve 2 transitions from a fully closed state to an approximately half-open state, and from an approximately half-open state to a fully closed state, and the length of the covering portion 42 and the attachment position of the covering portion 42 relative to the main body portion 41 are specified so that the metal wire (main body portion 41) is exposed when the main valve 2 transitions from an approximately half-open state to a fully open state, and from a fully open state to an approximately half-open state, and the covering portion 42 is not present at the portion facing the inner surface of the small hole 24h when the main valve 2 transitions from an approximately half-open state to a fully open state, and from a fully open state to an approximately half-open state. As a result, in the solenoid valve 1 of this example, the gap between the small hole 24h and the needle portion 25a is larger when the main valve 2 is transitioning between the approximately half-open state and the fully open state than when it is transitioning between the fully closed state and the approximately half-open state, and a configuration is adopted in which a larger amount of water passes through the small hole 24h per unit time when the main valve 2 is transitioning between the approximately half-open state and the fully open state than when it is transitioning between the fully closed state and the approximately half-open state.

[0031] On the other hand, the pilot valve 3 is an example of a "pilot valve" and, as shown in Fig. 3, includes a valve seat 31, a valve element 32, and an actuator (solenoid) 33. This pilot valve 3 employs a configuration in which the actuator 33 moves the valve element 32 away from the valve seat 31, thereby communicating the pressure chamber Sp and the downstream space So. The valve seat 31 is an example of a "first valve seat," and, as shown in Figs. 3, 4, and 6, is formed on the plate-shaped portion 24 of the valve element 22 in the main valve 2. Specifically, in the solenoid valve 1 (pilot valve 3) of this example, a valve port 31h (an example of a "first valve port") for allowing tap water to flow from the pressure chamber Sp to the downstream space So is formed on the plate-shaped portion 24 of the valve element 22 to form the valve seat 31 (an example of a configuration in which the "first valve seat" is provided on the "second valve element").

[0032] The valve element 32 is an example of a "first valve element," and is attached to the tip of a movable core (movable iron core: plunger) in the actuator 33, and is moved toward and away from the valve seat 31 by the actuator 33. The actuator 33 is an example of an "actuator," and moves the movable core toward and away from a fixed core (fixed iron core: hole piece) using power supplied from a control unit (not shown), thereby moving the valve element 32 toward and away from the valve seat 31. Note that the configuration of an "actuator" used in this type of "solenoid valve" is well known, so a detailed description will be omitted.

[0033] When using this solenoid valve 1, the upstream piping (supply source piping: not shown) is connected to the inlet Hi of the main body 11, the downstream piping (supply destination piping: not shown) is connected to the outlet Ho, and a control unit is connected to the actuator 33. When tap water is supplied via the upstream piping in this state, the tap water flows from the inlet Hi into the upstream space Si, and foreign matter is removed as it passes through the filter 4. Furthermore, the tap water that has passed through the filter 4 flows from the upstream space Si into the pressure chamber Sp through the small hole 24h (the gap between the inner surface of the small hole 24h and the outer circumferential surface of the needle portion 25a), and the upstream space Si and the pressure chamber Sp become filled with tap water.

[0034] At this time, in the solenoid valve 1 of this example, the valve element 22 is pressed against the valve seat 21 by the biasing force of the spring 25 (coil portion) and the spring in the actuator 33, and the valve port 21h is closed by the valve element 22, so the water pressure in the pressure chamber Sp gradually increases to the same level as the water pressure in the upstream space Si, i.e., the same level as the water pressure in the supply source piping. In this state, the water pressure in the pressure chamber Sp is higher than the pressure in the downstream space So, so the main valve 2 remains closed, and the passage of tap water is restricted.

[0035] On the other hand, when allowing tap water to pass from the upstream pipe (upstream space Si) to the downstream pipe (downstream space So), the actuator 33 is operated to switch the pilot valve 3 to an open state. Specifically, as shown in FIG. 3, the valve element 32, which is in contact with the valve seat 31 and closing the valve port 31h, is moved away from the valve seat 31 by the actuator 33 (moved upward in the figure), thereby opening the valve port 31h. At this time, tap water in the pressure chamber Sp is forced to flow out from the valve port 31h into the downstream space So, causing the pressure in the pressure chamber Sp to become lower than the pressure in the upstream space Si. As a result, the valve element 22 is moved away from the valve seat 21 against the biasing force of the spring 25, switching the main valve 2 to an open state, and the valve port 21h is opened, connecting the upstream space Si and the downstream space So and allowing tap water to pass through.

[0036] Furthermore, when the passage of tap water is to be restricted again, the actuator 33 is operated to transition the pilot valve 3 to the closed state. Specifically, in contrast to the transition from the closed state to the open state, the actuator 33 moves the valve element 32 toward the valve seat 31, causing the valve element 32 to close the valve port 31h. At this time, the force of the actuator 33 pressing the valve element 32 toward the valve seat 31 (the plate-shaped portion 24 of the valve element 22) and the force applied to the valve element 22 by tap water that has flowed from the upstream space Si into the pressure chamber Sp through the small hole 24h (the gap between the inner surface of the small hole 24h and the outer circumferential surface of the needle portion 25a) move the valve element 22 toward the valve seat 21, thereby closing the valve port 21h. This transition of the main valve 2 to the closed state restricts the passage of tap water.

[0037] Furthermore, when the valve port 21h is closed by the valve element 22, tap water flows from the upstream space Si into the pressure chamber Sp through the small hole 24h, gradually increasing the water pressure in the pressure chamber Sp until the water pressure in the pressure chamber Sp becomes sufficiently higher than the pressure in the downstream space So. This maintains the closed state of the main valve 2. Note that when the main valve 2 transitions from the open state to the closed state, the flow of tap water from the upstream space Si (inlet port Hi) to the downstream space So (outlet port Ho) is stopped by the main valve 2, which may cause a water hammer phenomenon in which the water pressure in the upstream space Si and in the supply-source piping connected to the inlet port Hi temporarily rises.

[0038] In this case, in the solenoid valve 1 of this example, as described above, the length of the covering portion 42 of the needle portion 25a and the attachment position of the covering portion 42 relative to the body portion 41 are specified so that the amount of water passing through the small hole 24h per unit time is greater when the main valve 2 is transitioning between the approximately half-open state and the fully open state than when the main valve 2 is transitioning between the approximately half-open state and the fully closed state. Therefore, when the main valve 2 is transitioned from the fully open state to the fully closed state, immediately after the start of the valve closing operation, a sufficiently large amount of tap water flows into the pressure chamber Sp per unit time via the small hole 24h, allowing the main valve 2 to transition from the fully open state to the approximately half-open state in a relatively short time, and when transitioning from the approximately half-open state to the fully closed state, the amount of tap water flowing into the pressure chamber Sp per unit time decreases, so that the transition to the fully closed state takes longer than the time required to transition from the fully open state to the approximately half-open state, thereby making it possible to suitably suppress the occurrence of the water hammer phenomenon.

[0039] The applicant has confirmed that by specifying the length of the covering portion 42 and the attachment position of the covering portion 42 relative to the main body portion 41 so that the opening rate of the main valve 2 is within the range of 30% to 50% (for example, an opening rate of 40%), which corresponds to the above-mentioned "approximately half-open state," it is possible to suitably suppress the occurrence of the water hammer phenomenon while sufficiently shortening the time required to complete the transition from the fully open state to the fully closed state under various usage environments.

[0040] Here, the solenoid valve 1 of this example is configured to remove foreign matter mixed in the tap water introduced from the inlet Hi using the filter 4, but if small foreign matter that has passed through the filter 4 accumulates on the inner surface of the small hole 24h, the flow rate of tap water passing through the small hole 24h per unit time when transitioning from the open state to the closed state decreases, resulting in an excessively long time required to transition to the fully closed state, or in the worst case, difficulty in transitioning to the fully closed state. Therefore, the solenoid valve 1 of this example is configured to clean the inside of the small hole 24h (remove foreign matter from inside the small hole 24h) by inserting the needle portion 25a into the small hole 24h as described above when the main valve 2 opens and closes.

[0041] On the other hand, in the solenoid valve 1 of this example, as described above, the valve element 22 and the spring 25 (needle portion 25a) are formed so that the maximum outer diameter L42b of the needle portion 25a (covered portion 42) is slightly smaller than the inner diameter L22 of the small hole 24h, and a gap is formed between the needle portion 25a (covered portion 42) and the inner surface of the small hole 24h. However, it is difficult to always keep the needle portion 25a (covered portion 42) and the inner surface of the small hole 24h out of contact between the fully closed state and the approximately half-open state, and when the valve element 22 moves relative to the needle portion 25a during the opening and closing operations of the main valve 2, the valve element 22 may move relative to the needle portion 25a with the inner surface of the small hole 24h in contact with the needle portion 25a (covered portion 42) (the valve element 22 may slide relative to the needle portion 25a).

[0042] In this case, if a cleaning pin whose entire portion facing the small hole 24h between the fully closed state and the fully open state is used instead of the needle portion 25a of the present example, and whose entire portion facing the small hole 24h is made of metal wire such as stainless steel (a cleaning pin whose metal wire is exposed and not covered with the coating portion 42, etc.), wear will occur on the inner surface of the small hole 24h (the plate-shaped portion 24 of the valve body 22), which is more susceptible to wear than a metal cleaning pin, changing the opening shape of the small hole 24h and increasing its opening area. In this state, the flow rate of tap water passing through the small hole 24h per unit time during the transition from the open state to the closed state increases compared to the state before the wear on the inner surface of the small hole 24h occurred. As a result, the time required for the water pressure in the pressure chamber Sp to increase is shortened, and the transition to the closed state is completed more quickly than expected, which may make it difficult to suppress the water hammer phenomenon as expected.

[0043] Therefore, the solenoid valve 1 of this embodiment is configured to prevent the main body 41 from contacting the inner surface of the small hole 24h between the fully closed state and the approximately half-open state by attaching a covering portion 42 to the tip side of the metal main body 41 that constitutes the needle portion 25a. Between the approximately half-open state and the fully open state, the outer diameter of the main body 41 is sufficiently small compared to the inner diameter of the small hole 24h, sufficiently reducing the possibility of the main body 41 contacting the inner surface of the small hole 24h. Furthermore, in the solenoid valve 1 of this embodiment, the covering portion 42 that covers the tip side of the main body 41 is made of a resin material. This ensures that the portion (covering portion 42) that comes into contact with the inner surface of the small hole 24h during the opening and closing operation of the main valve 2 (during the cleaning operation of the small hole 24h by the needle portion 25a) and the valve element 22 (the inner surface of the small hole 24h in the plate-shaped portion 24) have similar wear characteristics during sliding. As a result, compared to a configuration that uses a cleaning pin formed from metal wire, scraping of the inner surface of the small hole 24h due to sliding against the needle portion 25a (coating portion 42) is sufficiently suppressed, and changes in the opening shape and opening area of ​​the small hole 24h are sufficiently suppressed.

[0044] Furthermore, in the solenoid valve 1 of this example, as described above, the opening shape of the small hole 24h is circular, and the cross-sectional shape of the needle portion 25a (covering portion 42) is non-circular (in this example, gear shape). In this case, in a configuration in which both the opening shape of the small hole 24h and the cross-sectional shape of the cleaning pin are circular, in order to preferably suppress the reduction in water hammer as in the solenoid valve 1 of this example, it is necessary to make the diameter of the cleaning pin smaller than the maximum diameter portion of the needle portion 25a (covering portion 42) in the solenoid valve 1.

[0045] In this configuration, the distance between the small diameter cleaning pin and the inner surface of small hole 24h is greater than the distance between the inner surface of small hole 24h and the maximum diameter portion of needle portion 25a in solenoid valve 1. For this reason, if the opening shape of small hole 24h and the cross-sectional shape of the cleaning pin are both circular, the cleaning pin is more likely to move around (move radially) within small hole 24h during cleaning operation, which may result in the cleaning pin being hit hard against the inner surface of small hole 24h, which may cause deformation such as scraping of small hole 24h.

[0046] In contrast, in the solenoid valve 1 of this embodiment, in which the opening shape of the small hole 24h is circular and the cross-sectional shape of the needle portion 25a (covering portion 42) is non-circular (gear-shaped), the presence of the minimum diameter portion of the needle portion 25a ensures a sufficient effective passage area, while making it possible to sufficiently shorten the distance between the maximum diameter portion of the needle portion 25a and the inner surface of the small hole 24h. Therefore, in the solenoid valve 1 of this embodiment, the needle portion 25a is less likely to move wildly (move radially) within the small hole 24h during a cleaning operation, so that the needle portion 25a is not strongly struck against the inner surface of the small hole 24h, and deformation such as scraping of the small hole 24h is less likely to occur.

[0047] Thus, this solenoid valve 1 is provided with a main valve 2 in which the valve body 22 is moved toward or away from the valve seat 21 due to the pressure difference between the pressure in the upstream space Si in the flow path of the fluid to be controlled and the pressure in the pressure chamber Sp to which the valve port 31h of the pilot valve 3 is connected, and the main valve 2 has a small hole 24h in the valve body 22 that connects the upstream space Si with the pressure chamber Sp, and is provided with a needle portion 25a (cleaning pin) inserted into the small hole 24h, and the needle portion 25a has a metal main body portion 41 and a resin covering portion 42 that covers at least the tip end portion of the main body portion 41 in the longitudinal direction.

[0048] Therefore, with this solenoid valve 1, even if the valve element 22 is caused to slide relative to the needle portion 25a while the inner surface of the small hole 24h is in contact with the needle portion 25a during cleaning operation (during opening and closing of the main valve 2), there is no significant difference in the likelihood of wear between the inner surface of the small hole 24h and the covering portion 42 of the needle portion 25a, so it is possible to avoid significant abrasion of the inner surface of the small hole 24h due to sliding between the needle portion 25a (covering portion 42) and the small hole 24h. This makes it possible to prevent the opening shape and opening area of ​​the small hole 24h from changing in a short period of time, thereby maintaining constant characteristics of the solenoid valve 1 over a long period of time.

[0049] Furthermore, in this solenoid valve 1, the valve body 22 and the needle portion 25a are formed so that the opening shape of the small hole 24h and the cross-sectional shape of the covering portion 42 of the needle portion 25a are different. Specifically, in this solenoid valve 1, the opening shape of the small hole 24h is circular, and the cross-sectional shape of the covering portion 42 is non-circular. Therefore, with this solenoid valve 1, it is possible to ensure a sufficient effective passage area for tap water between the inner surface of the small hole 24h and the needle portion 25a (covering portion 42), while suitably preventing the needle portion 25a from moving wildly within the small hole 24h during cleaning operation (during opening and closing operation of the main valve 2), thereby more suitably preventing significant abrasion from occurring on the inner surface of the small hole 24h.

[0050] The configuration of the "solenoid valve" is not limited to the example of the configuration of the solenoid valve 1 described above.

[0051] For example, as an example of a configuration in which the opening shape of the small hole and the cross-sectional shape of the cylindrical body of the cleaning pin are different, the solenoid valve 1 in which the opening shape of the small hole 24h is circular and the cross-sectional shape of the needle portion 25a (covering portion 42) is non-circular (gear-shaped) has been described. However, instead of this configuration, the opening shape of the "small hole" can be non-circular and the cross-sectional shape of the "cylindrical body" of the "cleaning pin" can be circular. Specifically, as shown in FIG. 9, instead of the spring 25 having the needle portion 25a, a spring 26 having a needle portion 26a (another example of a "cleaning pin") with a circular cross section can be used, and instead of the valve body 22, a valve body 22a having a plate-shaped portion 24a with a small hole 24ha (another example of a "small hole") with a non-circular opening shape can be provided. Note that in the example shown in the figure, components having the same functions as corresponding components of the solenoid valve 1 described above are designated by the same reference numerals, and redundant description will be omitted. Moreover, components other than those shown in the figure are the same as the components of the solenoid valve 1, and detailed explanations thereof will be omitted.

[0052] In the example configuration shown in the figure, needle portion 26a is configured by disposing covering portion 43, which is another example of a "resin cylinder," at the tip end of main body 41, instead of covering portion 42 of needle portion 25a. In this example configuration, the cross-sectional shape of covering portion 43 in needle portion 26a is circular with an outer diameter L43 of approximately 0.7 mm, while the opening shape of small hole 24ha is non-circular with a minimum inner diameter L22a of approximately 0.9 mm and a maximum inner diameter L22b of approximately 1.1 mm, and they are integrated together. As a result, in this example configuration, when the needle portion 26a is inserted through the small hole 24ha with the centers aligned, a gap of approximately 0.2 mm is formed between the inner surface of the small hole 24ha's minimum diameter portion and the covering portion 43, and a gap of approximately 0.1 mm is formed between the inner surface of the small hole 24ha's maximum diameter portion and the covering portion 43, allowing tap water to flow from the upstream space Si into the pressure chamber Sp through such gaps. Even with this configuration including the valve body 22a (small hole 24ha) and the needle portion 26a (main body portion 41 and covering portion 43), it is possible to achieve the same effects as the aforementioned solenoid valve 1 including the valve body 22 (small hole 24h) and the needle portion 25a (main body portion 41 and covering portion 42).

[0053] Furthermore, although an example has been described in which the opening shape of the small hole and the cross-sectional shape of the cylindrical body of the cleaning pin are different, it is also possible to adopt a configuration in which the opening shape of the small hole and the cross-sectional shape of the cylindrical body of the cleaning pin are the same (for example, a configuration in which both are circular) (not shown). Even in such a configuration, by forming the "cylinder" from resin, it is possible to effectively prevent the inner surface of the "small hole" from being scraped during the cleaning operation (valve opening operation). [Explanation of symbols]

[0054] 1 solenoid valve 2 Main valve 3 Pilot valve 4 Filters 10 Body 11 Body 12 Guide member 21,31 Valve seat 21h,31h Benguchi 22, 22a, 32 Valve body 23 Valvular region 23ha, 23hb insertion hole 24, 24a Plate-shaped part 24h,24ha small hole 25,26 Spring 25a, 26a Needle part 33 Actuator 41 Main body 42,43 Covering part Hi inlet Ho outlet L22, L22a, L22b inner diameter L42a, L42b, L43 outer diameter Si Upstream space So downstream space Sp pressure chamber

Claims

1. a pilot valve including a first valve seat provided with a first valve port, a first valve body movable toward and away from the first valve seat, and an actuator for moving the first valve body toward and away from the first valve seat; a main valve having a second valve seat provided with a second valve port, and a second valve body that is movable toward and away from the second valve seat, and the second valve body is movable toward and away from the second valve seat depending on a pressure difference between a pressure in an upstream space in a flow path of a fluid to be controlled and a pressure in a pressure chamber that is communicated with the first valve port, the main valve has a small hole in the second valve body that connects the upstream space with the pressure chamber, and the main valve has a cleaning pin that is inserted into the small hole; The cleaning pin is an electromagnetic valve having a metal pin body and a resin cylindrical body that covers at least the tip end portion of the pin body in the longitudinal direction.

2. 2. The solenoid valve according to claim 1, wherein the second valve body and the cleaning pin are formed so that the opening shape of the small hole in the main valve differs from the cross-sectional shape of the cylindrical body of the cleaning pin.

3. 3. The solenoid valve according to claim 2, wherein the opening of the small hole of the main valve is circular, and the cross section of the cylindrical body is non-circular.

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