Solenoid valve

Abstract

A solenoid valve comprises: a valve body 12 having a main valve chamber 13, a pilot valve chamber 19, an inflow passage 14, an outflow passage 15, and a main valve port 16; a main valve element 18 for opening and closing the main valve port; a pilot passage 21 for selectively allowing the pilot valve chamber and the outflow passage to communicate; a pressure equalization passage 23 for allowing the main valve chamber and the pilot valve chamber to communicate; a pilot valve port 22 formed at the pilot-valve-chamber-side end part of the pilot passage; a pilot valve element 20 for opening and closing the pilot passage; and a drive device 24 including a plunger 27 and a suction element member 28 that are connected to the pilot valve element so as to be capable of moving relatively in the direction of an axis A and are supported so as to be capable of sliding in the axial direction, the drive device driving the pilot valve element. The solenoid valve furthermore comprises a rod-form member 29 fixed to the plunger, the rod-form member abutting on the main valve element when the valve is closed and pressing the main valve element in a valve-closing direction.

Description

Solenoid valve

[0001] The present invention relates to a solenoid valve, and more particularly to a pilot-operated solenoid valve that opens and closes a main valve by a pilot valve.

[0002] A pilot-operated solenoid valve that opens and closes a pilot valve by an electromagnetic actuator and opens and closes a main valve in response to the opening and closing of the pilot valve has been conventionally used in a refrigeration cycle apparatus equipped with a refrigerant circuit such as an air conditioner, a refrigerator, or a freezer.

[0003] Fig. 11 shows an example of a conventional pilot-operated solenoid valve. As shown in this figure, the solenoid valve includes a valve body 12 having a main valve chamber 13 and a pilot valve chamber 19 inside, an inflow passage 14 for allowing fluid to flow into the main valve chamber 13, and an outflow passage 15 for allowing fluid to flow out of the main valve chamber 13, a main valve port 16 formed at an end of the outflow passage 15 on the main valve chamber side, a main valve body 18 that moves forward and backward with respect to the main valve port 16 to open and close the outflow passage 15, a pilot passage 21 that selectively communicates the pilot valve chamber 19 and the outflow passage 15 through the main valve body 18, a pressure equalizing passage 23 that communicates the main valve chamber 13 and the pilot valve chamber 19, a pilot valve port 22 formed at an end of the pilot passage 21 on the pilot valve chamber side, a pilot valve body 20 that moves forward and backward with respect to the pilot valve port 22 to open and close the pilot passage 21, and an electromagnetic drive device 24 that drives the pilot valve body 20.

[0004] The electromagnetic drive device 24 includes a cylindrical plunger 27 housed in a sleeve 26 and supported slidably in the axial direction of the axis A, an attracting member 28 that attracts the plunger 27, and a spring member (pilot valve body pressing spring) 30 provided in the plunger 27 to bias the pilot valve body 20 toward the pilot valve port 22. The pilot valve body 20 and the plunger 27 are assembled so as to be relatively movable in the axial direction.

[0005] Further, there is the following Patent Document 1 that discloses a pilot-operated solenoid valve.

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2023 - 104598

[0007] Incidentally, in conventional pilot-operated solenoid valves, the main valve body that opens and closes the main valve port is opened and closed by differential pressure (the load generated by the pressure difference between the inlet and outlet sides). For this reason, the sealing performance (fluid blocking) of the main valve port when closed depends on this differential pressure, and when the differential pressure is small, valve leakage is more likely to occur.

[0008] Therefore, the objective of the present invention is to prevent valve leakage at low differential pressures.

[0009] To solve the aforementioned problems and achieve the objective, the pilot-operated solenoid valve according to the present invention comprises a valve body having a main valve chamber and a pilot valve chamber inside, an inlet passage through which fluid (e.g., refrigerant) flows into the main valve chamber and an outlet passage through which fluid flows out of the main valve chamber, and a main valve port formed at the main valve chamber side end of the outlet passage; a main valve element that opens and closes the outlet passage by moving back and forth relative to the main valve port; a pilot passage that penetrates the main valve element and connects the pilot valve chamber and the outlet passage; a pressure equalizing passage that connects the main valve chamber and the pilot valve chamber; a pilot valve port formed at the pilot valve chamber side end of the pilot passage; and a pilot valve element that moves back and forth relative to the pilot valve port. The solenoid valve comprises a pilot valve body having a tip that opens and closes a pilot passage and is inserted into the pilot valve port when the valve is closed, and an electromagnetic drive device (sometimes simply referred to as "drive device" in this application) that drives the pilot valve body, which includes a plunger connected to the pilot valve body so as to be axially movable and supported so as to be axially slidable, and a sucker that attracts the plunger, wherein the solenoid valve comprises a pressing part provided on or supported by the plunger that, when the main valve body is in the closed state, contacts a part of the main valve body different from the part that the pilot valve body contacts, thereby pressing the main valve body in the closing direction.

[0010] The pressing portion may be configured to move axially integrally with the plunger. The pressing portion is, for example, rod-shaped. Furthermore, the "pressing portion" is, as an example of a rod shape, a rod-shaped member that is fixed to the plunger. The rod-shaped pressing portion or rod-shaped member is a long portion or member that extends in the axial direction. The rod-shaped member is typically a hollow (cylindrical or pipe-shaped) member, as in the embodiments described later. However, the rod-shaped member may be a solid member. In that case, for example, multiple solid rod-shaped members may be provided, and these multiple rod-shaped members can be arranged parallel to the pilot valve body and in a ring around the pilot valve body. The arrangement and number of rod-shaped pressing portions or rod-shaped members are not limited to the examples described above and may vary. Furthermore, the pressing portion may be formed integrally with the plunger, for example. Integral here means that the plunger and the pressing portion are a single member. In other words, the pressing portion is not formed integrally with the plunger by fixing a separate component; rather, a part of the plunger may form the pressing portion.

[0011] Furthermore, the "axial direction" mentioned above refers to the direction of operation (movement) of the main valve body, pilot valve body, and plunger. In this application, one of the axial directions is designated as "up" and the other as "down," and the electromagnetic drive device is positioned above the valve body, with the valve body positioned below the electromagnetic drive device. However, the solenoid valve of the present invention can be used in various orientations (positions) (for example, lying on its side or at an angle), and the terms "up" and "down" (similarly for "upper surface," "lower surface," "upper side," "lower side," "upward," "downward," "up and down," etc.) are merely convenient (relative) concepts to facilitate understanding of the present invention (the same applies to the embodiments described later). In addition, the terms "ascending" and "descending" are sometimes used, with "ascending" meaning movement in the upward direction and "descending" meaning movement in the downward direction.

[0012] Furthermore, in this application, a valve that includes a main valve body provided in the main valve chamber and opens and closes the fluid passage (main valve port) from the inlet passage to the outlet passage is referred to as the "main valve." Also, a valve that includes a pilot valve body and opens and closes the pilot passage formed in the main valve body is referred to as the "pilot valve."

[0013] In the solenoid valve according to the present invention, a pressing portion provided on or supported by the plunger presses the main valve body in the closing direction when the main valve body is in the closed state, by contacting a portion of the main valve body different from the portion of the main valve body that the pilot valve body contacts. Therefore, in the solenoid valve according to the present invention, even when the differential pressure of the fluid (the pressure difference between the fluid on the inlet side and the outlet side) is small, the main valve body is pressed in the closing direction by the driving force of the electromagnetic drive device (i.e., the suction force that attracts the plunger to the suction element), thereby preventing valve leakage.

[0014] Furthermore, the pressing force applied by the pilot valve body to the main valve body is not increased. In other words, the pressing force applied from the pilot valve body to the pilot valve port or its vicinity when the valve is closed does not increase. For example, in a solenoid valve having a structure in which the pilot valve port is closed by the insertion of the tip of the pilot valve body, if the load on the pilot valve port from the pilot valve body increases, the pilot valve port may deform due to the use of the solenoid valve, and as a result, the durability of the solenoid valve may decrease. However, according to the present invention, the pressing force applied from the pilot valve body to the pilot valve body is not increased in order to suppress valve leakage. Or, the degree of increase in pressing force can be reduced. Therefore, a decrease in the durability of the solenoid valve can be prevented or suppressed.

[0015] In a preferred embodiment, the solenoid valve according to the present invention may further comprise one to four of the following structures (1) to (4) (any one or more combinations thereof).

[0016] (1) The pressing portion contacts the surface of the main valve body around the pilot valve opening when the main valve body is closed, and the surface to which the pressing portion contacts is made of one of the following: resin, rubber, and elastomer.

[0017] In order to improve sealing performance and prevent valve leakage, at least a part of the main valve body (especially the central part that closes the main valve opening) may be formed from an elastic material such as resin, rubber, or elastomer. If the part that the pressing part contacts is made of resin, rubber, or elastomer, as in structure (1) above, the noise when the valve is closed (the collision noise when the pressing part contacts the main valve body) can be reduced. The resin may be natural resin or synthetic resin. The rubber may be natural rubber or synthetic rubber. In particular, if structure (2) described below is also provided, it is possible to further reduce the collision noise when the valve is closed. In the conventional solenoid valve described above, a noise is generated when the plunger collides with the suction element when the valve is closed (this is a metal-to-metal collision noise), but if structures (1) and (2) are provided, it is possible to prevent this metal-to-metal collision noise from occurring.

[0018] (2) In the closed valve state where the pressing part is in contact with the main valve body, the plunger does not come into contact with the suction element, and a gap is formed between the plunger and the suction element.

[0019] (3) The valve comprises a plunger return spring that biases the plunger away from the main valve body and a pilot valve body pressing spring that biases the pilot valve body towards the main valve body, wherein the plunger and the pilot valve body are connected by contact such that they press against each other in the axial direction due to the biasing force of the plunger return spring and the biasing force of the pilot valve body pressing spring, and are able to move relative to each other against the biasing force of the plunger return spring or the biasing force of the pilot valve body pressing spring, and the pressing part moves relative to the main valve body together with the plunger to move closer to the main valve body even after the relative movement between the pilot valve body and the main valve body stops when the pilot valve body comes into contact with the pilot valve opening during valve closing operation.

[0020] With the above structure (3), the pilot valve body is brought into contact with the pilot valve port before the pressing part contacts the main valve body during the valve closing operation, thereby closing the pilot passage and ensuring that the main valve (main valve body) is reliably operated by the pilot valve.

[0021] Furthermore, when adopting the above structure (3), it is preferable to configure the plunger return spring as a coil spring and to configure the pressing portion as a cylindrical shape such that a part of its axial direction is inside the plunger return spring and along the inner circumferential surface of the plunger return spring. With such a structure, the pressing portion can guide (support) the plunger return spring from the inside, and it is possible to prevent situations that would adversely affect the opening and closing operation of the valve, such as the plunger return spring tilting or getting caught between the plunger and the suction element during the opening and closing operation of the valve.

[0022] (4) The valve is equipped with a stopper member made of an elastic material that the pilot valve body abuts against when the valve is opened, so that the plunger, which moves away from the main valve body when the valve is opened, stops when the pilot valve body abuts against the stopper member. With such a structure (4), the impact noise when the valve is opened can also be reduced.

[0023] According to the present invention, valve leakage can be prevented at low differential pressures.

[0024] Other objects, features, and advantages of the present invention will be made clearer by the following description of embodiments of the invention based on the drawings. It should be noted that the present invention is not limited to the embodiments described below, and it will be apparent to those skilled in the art that various modifications can be made within the scope of the claims. Furthermore, in each figure, the same reference numerals indicate the same or corresponding parts.

[0025] Figure 1 is a longitudinal cross-sectional view showing the open state of a solenoid valve according to the first embodiment of the present invention. Figure 2 is an enlarged longitudinal cross-sectional view (part B in Figure 1) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the first embodiment, showing the open state. Figure 3 is an enlarged longitudinal cross-sectional view (part B in Figure 1) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the first embodiment, showing the closed operation (pilot valve closed). Figure 4 is an enlarged longitudinal cross-sectional view (part B in Figure 1) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the first embodiment, showing the closed operation (main valve closed after the pilot valve). Figure 5 is an enlarged longitudinal cross-sectional view (part B in Figure 1) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the first embodiment, showing the closed state (rod-shaped member in contact with the main valve body). Figure 6 is a longitudinal cross-sectional view showing the open state of a solenoid valve according to the second embodiment of the present invention. Figure 7 is an enlarged longitudinal cross-sectional view (part C in Figure 6) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the second embodiment, showing the open state. Figure 8 is an enlarged longitudinal cross-sectional view (part C in Figure 6) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the second embodiment, showing the closed operation (pilot valve closed). Figure 9 is an enlarged longitudinal cross-sectional view (part C in Figure 6) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the second embodiment, showing the closed operation (main valve closed after the pilot valve). Figure 10 is an enlarged longitudinal cross-sectional view (part C in Figure 6) showing the main parts (main valve, pilot valve, and electromagnetic drive device) of the solenoid valve according to the second embodiment, showing the closed state (rod-shaped member in contact with the main valve body). Figure 11 is a longitudinal cross-sectional view showing an example of a conventional solenoid valve (open state). Figure 12 is a longitudinal cross-sectional view showing an example of the configuration of a solenoid valve according to the third embodiment of the present invention. Figure 13 is a diagram showing the closed state of the solenoid valve of the third embodiment. Figure 14 is a diagram showing the open state of the solenoid valve of the third embodiment. Figure 15 is a diagram showing a comparison of the assembly of the solenoid valve of the third embodiment and the solenoid valve of a comparative example.Figure 16 shows an example of a cartridge-type solenoid valve.

[0026] [First Embodiment] A solenoid valve according to the first embodiment of the present invention will be described based on Figures 1 to 5.

[0027] As shown in Figures 1 to 5, the solenoid valve 11 according to the first embodiment of the present invention is a normally open type (normally open) pilot-operated solenoid valve that is open when not energized, and has a valve body 12 having a main valve chamber 13 and a pilot valve chamber 19 inside, and an inlet passage 14 for allowing fluid to flow into the main valve chamber 13 and an outlet passage 15 for allowing fluid to flow out of the main valve chamber 13, and a main valve port 16 formed at the main valve chamber side end of the outlet passage 15, and the outlet passage 15 (main valve port 16) moves back and forth relative to the main valve port 16 The system includes a main valve body 18 that opens and closes the valve, a pilot passage 21 that passes through the main valve body 18 and selectively connects the pilot valve chamber 19 and the outflow passage 15, a pressure equalization passage 23 that connects the main valve chamber 13 and the pilot valve chamber 19, a pilot valve port 22 formed at the pilot valve chamber side end of the pilot passage 21, a pilot valve body 20 that opens and closes the pilot passage 21 by moving back and forth relative to the pilot valve port 22, and a drive device (electromagnetic drive device) 24 that drives the pilot valve body 20.

[0028] Furthermore, the drive unit 24 includes a plunger 27 supported so as to be slidable in the direction of axis A within a sleeve 26 (described later), a suction member 28 that attracts the plunger 27, and a coil 25 that generates a magnetic force to attract the plunger 27.

[0029] A bottomless, lidless vertical hole (with an open upper end and a bottom surface at the lower end) is formed in the valve body 12, extending downward vertically from the upper surface of the valve body 12 (i.e., in the direction of the axis A of the solenoid valve 11), and the space below this vertical hole is made into the main valve chamber 13. An inlet passage 14 is opened at the periphery of the bottom surface of the main valve chamber 13, allowing refrigerant to flow into the main valve chamber 13. An outlet passage 15 is also opened in the center of the bottom surface of the main valve chamber 13. At the end of the outlet passage 15 on the main valve chamber side, a main valve opening 16 is formed, rising vertically upward, and the upper surface (upper end) of the main valve opening 16 is a main valve seat 17 to which the main valve body 18 moves toward and toward (contacts and separates).

[0030] The space above the vertical hole serves as a connection opening for fixing the suction element member 28. The suction element member 28 has a ring-shaped connection portion 28b, which is fixed by being screwed into the connection opening and has a male thread on its outer surface that screws into a female thread formed on the inner surface of the connection opening, and a cylindrical suction element body 28a that rises upward from the center of the upper surface of the connection portion 28b.

[0031] The central hole 28d, which penetrates the inside of the connecting portion 28b, i.e., the center of the connecting portion 28b in the vertical direction, serves as a main valve body guide portion that supports the main valve body 18 so that it can slide in the vertical direction (in the direction of the axis A of the solenoid valve 11). The central hole 28d of the connecting portion 28b is in communication with the central hole 28c of the suction element body 28a, which will be described later.

[0032] The lower surface of the connecting portion 28b has a protruding portion that extends inward toward the center of the central hole 28d of the connecting portion 28b, and a main valve opening spring 32 is provided between this protruding portion and the lower peripheral edge of the main valve body 18. The main valve opening spring 32 is made of a compression coil spring (a coil spring installed in a compressed state / hereinafter the same) and biases the main valve body 18 upward (i.e., in the valve opening direction), performing the function of pushing the main valve body 18 upward when the drive device 24 is not driven. The upper peripheral edge of the main valve body guide portion 28d has a stepped portion formed to stop the main valve body 18 that has been pushed up by the main valve opening spring 32.

[0033] The suction element body 28a has a central hole 28c that penetrates in the vertical direction. A sleeve 26 is fixed to the outer peripheral surface of the upper end of the suction element body 28a so as to rise upward from the upper end of the suction element body 28a. The sleeve 26 is a cylindrical member with no bottom and a cap (closed on the top and open on the bottom), and houses a plunger 27 inside so as to be slidable in the vertical direction. The plunger 27 has a bottom portion 27a that is attracted to the suction element body 28a by the magnetic force generated by a coil 25 provided on the outer peripheral surface of the sleeve 26, and a ring-shaped peripheral wall portion 27b that rises upward from the outer peripheral surface of the bottom portion 27a. A through hole is formed in the center of the bottom portion 27a that penetrates the bottom portion 27a in the vertical direction and communicates with the inside of the peripheral wall portion 27b. A pilot valve body 20 is provided so as to penetrate the through hole.

[0034] The pilot valve body 20 has a round rod-shaped valve body 20a and a large outer diameter valve head 20b formed at the upper end of the valve body 20a. The valve head 20b is positioned above the bottom portion 27a of the plunger 27, that is, inside the peripheral wall portion 27b. On the other hand, the valve body 20a is positioned to extend vertically downward through the through hole in the bottom portion 27a. The tip portion (lower end) of the valve body 20a has a needle-like (inverted cone) shape so that it can be inserted into the pilot valve port 22 when the valve is closed to close the pilot passage 21.

[0035] Inside the peripheral wall portion 27b of the plunger 27, a pilot valve body pressing spring 30 made of a compression coil spring is provided, interposed between the valve body head portion 20b and the top plate portion of the sleeve 26. Furthermore, at the lower end of the central hole 28c of the suction element body 28a, a protruding portion is provided that extends toward the center of the central hole 28c, and a plunger return spring 31 made of a compression coil spring is provided, interposed between this protruding portion and the lower surface portion of the plunger 27 (bottom portion 27a).

[0036] The pilot valve body pressing spring 30 biases the pilot valve body 20 in the closing direction (downward), pressing the valve body head 20b of the pilot valve body 20 against the bottom 27a of the plunger 27. On the other hand, the plunger return spring 31 biases the plunger 27 upward. Therefore, the plunger 27 and the pilot valve body 20 are in contact, pressing against each other in the direction of axis A, and are connected so as to be able to move relative to each other in the direction of axis A. In addition, the plunger return spring 31 has the function of pulling the plunger 27 upward when the drive unit 24 is not driven. As the plunger 27 rises, the valve body head 20b is pulled up, and the pilot valve body 20 also moves upward.

[0037] Furthermore, a pipe member 29 is fixed to the bottom 27a of the plunger 27. This pipe member 29 corresponds to the pressing part as referred to in the present invention. Moreover, it corresponds to a rod-shaped member, which is an example of a pressing part. The pipe member 29 is made of a non-magnetic material so as not to hinder the function of the drive device 24 (attraction of the plunger 27 by the suction element member 28), and is installed so as to extend vertically downward from the bottom 27a of the plunger 27 toward the main valve body 18. The valve body 20a of the pilot valve body 20 passes through this pipe member 29, and the tip (lower end) of the valve body 20a protrudes downward from the lower end of the pipe member 29. In addition, the plunger return spring 31 is arranged along the outer circumferential surface of the pipe member 29. To put it another way, the pipe member 29 is arranged inside the plunger return spring 31 so as to support the plunger return spring 31 from the inside.

[0038] Furthermore, the pipe member 29 and the plunger return spring 31 are arranged to slide relative to each other in the vertical direction. Similarly, the pipe member 29 and the pilot valve body 20 are also provided to slide relative to each other in the vertical direction. In addition, the pipe member 29 and the pilot valve body 20 pass through the central hole 28c of the suction element body 28a, and the tips of them (pipe member 29 and pilot valve body 20) protrude downward (into the pilot valve chamber 19) from the central hole 28c of the suction element body 28a.

[0039] The main valve body 18 consists of a ring-shaped outer circumference 18a of the main valve and a main valve body 18b fixed to the inside of the outer circumference 18a of the main valve. The main valve body 18b is made of a resin material (rubber or elastomer may also be used) that has excellent sealing properties (valve leakage prevention function) when the valve is closed. The resin material may be a natural resin or a synthetic resin. The rubber may be a natural rubber or a synthetic rubber. An example of a resin material is PTFE. An example of a rubber is EPDM. The pilot passage 21 penetrates the center of the main valve body 18 (main valve body 18b) in the vertical direction. The pressure equalization passage 23 penetrates the peripheral edge of the main valve body 18 (outer circumference 18a of the main valve) in the vertical direction. The pilot valve chamber 19 is formed on the upper side of the main valve body 18 (between the upper surface of the main valve body 18 and the lower surface of the suction element body 28a).

[0040] In the solenoid valve 11 of this embodiment, the plunger 27, pilot valve body 20, pipe member 29, suction element member 28 (suction element body 28a and connecting part 28b), main valve body 18, pilot passage 21 (pilot valve port 22), and main valve port 16 (main valve seat 17) are arranged coaxially, and their central axes coincide with the axis A of the solenoid valve 11.

[0041] The operation of the solenoid valve 11 in this embodiment is as follows:

[0042] When the drive unit 24 is not driven (when the coil 25 is not energized), as shown in Figures 1 and 2, the plunger 27 is pushed upward against the biasing force of the pilot valve body pressing spring 30 by the biasing force of the plunger return spring 31 and pressed against the top plate of the sleeve 26. Consequently, the pilot valve body 20 is pulled upward by the plunger 27, and the pilot passage 21 (pilot valve port 22) is opened. Therefore, the refrigerant that flows from the inlet passage 14 into the main valve chamber 13 and through the pressure equalization passage 23 into the pilot valve chamber 19 does not accumulate in the pilot valve chamber 19 but is discharged from the outlet passage 15 through the pilot passage 21. Consequently, the pressure in the pilot valve chamber 19 does not increase, and the main valve body 18 is pushed upward by the biasing force of the main valve opening spring 32, which biases the main valve body 18 upward (in the opening direction), and the main valve port 16 is opened. In this open state, the refrigerant that flows from the inlet passage 14 into the main valve chamber 13 flows out through the main valve opening 16 and out of the outlet passage 15 (see arrow F).

[0043] When current is applied to the coil 25 from the open valve state described above, the plunger 27 is pushed down against the biasing force of the plunger return spring 31 by being attracted to the suction element body 28a. Consequently, the pipe member 29 fixed to the plunger 27 and the pilot valve body 20 connected to the plunger 27 descend together with the plunger 27, and as shown in Figure 3, the tip of the pilot valve body 20 is inserted into the pilot valve port 22, closing the pilot passage 21.

[0044] When the pilot passage 21 is closed as described above, the refrigerant flowing into the pilot valve chamber 19 through the pressure equalizing passage 23 is accumulated without being discharged through the pilot passage 21, and the pressure in the pilot valve chamber 19 rises. Then, when the force that pushes the main valve body 18 downward, which is caused by the refrigerant pressure in the pilot valve chamber 19 (more precisely, the differential pressure between the pilot valve chamber 19 and the main valve chamber 13) and the suction force of the armature body 28a (the downward force that sucks the plunger 27, that is, the downward force applied to the main valve body 18 through the pilot valve body 20), exceeds the upward biasing force of the main valve opening spring 32, the main valve body 18 descends and seats on the main valve seat 17 as shown in FIG. 4. In the state shown in FIG. 4, the pipe member 29 does not contact the main valve body 18, and there is a gap between them.

[0045] On the other hand, even after the main valve body 18 seats on the main valve seat 17, the plunger 27 and the pipe member 29 descend due to the suction force of the armature body 28a. Then, as shown in FIG. 5, when the pipe member 29 abuts on the upper surface of the main valve body 18 (the main valve main body portion 18b), the descent of the plunger 27 and the pipe member 29 stops. In this closed valve state, a slight gap (air gap) G is formed between the armature body 28a and the plunger 27 (the bottom portion 27a). The reason for forming the air gap G in this way is to surely abut the pipe member 29 on the main valve body 18 when closing the valve (if the plunger 27 abuts on the armature body 27a first, the pipe member 29 cannot press the main valve body 18), press the main valve body 18 downward, and prevent valve leakage from the main valve port 16. Also, it is to prevent the collision sound between metals when closing the valve by preventing the collision between the plunger 27 and the armature member 28, which are both made of magnetic metal materials.

[0046] When the energization to the coil 25 is stopped from the above closed valve state, the suction force by which the armature body 28a attracts the plunger 27 disappears. Therefore, the plunger 27 is lifted against the biasing force of the pilot valve body pressing spring 30 by the biasing force of the plunger return spring 31, the pilot valve body 20 is pulled up, and the pilot passage 21 is opened.

[0047] When the pilot passage 21 is opened, the refrigerant accumulated in the pilot valve chamber 19 is discharged to the outflow passage 15 through the pilot passage 21, and the pressure in the pilot valve chamber 19 decreases. Furthermore, the cross-sectional area of the pilot passage 21 is larger than that of the pressure equalizing passage 23. Therefore, a differential pressure that pulls the main valve body 18 upward is generated on the upper and lower surfaces of the main valve body 18. In addition, the main valve body 18 receives an upward biasing force from the main valve opening spring 32. Due to these factors, the main valve body 18 is pushed upward, and the main valve body 18 is separated from the main valve seat 17, resulting in an open valve state in which the main valve port 16 is opened (see FIGS. 1 and 2). The raised main valve body 18 stops by abutting against a stepped portion formed at the upper end of the central hole (main valve body guide portion) 28d of the connection portion 28b of the attractor member 28. As a result, the pilot passage 21 remains open, and the open valve state is maintained.

[0048] Summing up the advantages of the solenoid valve 11 of the present embodiment provided with the pipe member 29, they are as follows.

[0049] (1) When the valve is closed, the main valve body 18 is pressed in the closing direction by the driving force of the drive device 24 (the suction force that the suction element member 28 exerts on the plunger 27), so that valve leakage can be prevented even when the pressure difference between the refrigerant on the inlet passage 14 side and the outlet passage 15 side is small. (2) When the valve is closed, the pipe member 29 presses on the upper surface of the main valve body 18 around the pilot valve port 22. Furthermore, because the pressure is applied by the pipe member 29, the pressing force input from the pilot valve body 20 to the pilot valve port 22 is not increased. Or, the degree of increase in the pressing force input from the pilot valve body 20 to the pilot valve port 22 can be reduced. As a result, the degree of deformation of the pilot valve port 22 associated with the use of the solenoid valve 11 can be prevented or suppressed, so that the deterioration of the durability of the solenoid valve 11 can be prevented or suppressed. (3) When the valve is closed, the pipe member 29 comes into contact with the main valve body 18b made of resin material, stopping the plunger 27 and preventing the plunger 27 from colliding with the suction element member 28. This prevents the generation of metal-to-metal collision noise during valve closing and reduces the collision noise during valve closing. (4) The plunger return spring 31 is supported from the inside by the pipe member 29, preventing the plunger return spring 31 from tilting or getting caught (pinched) between the plunger 27 and the suction element member 28. (5) In the conventional solenoid valve (Figure 11), it was necessary to increase the vertical dimension of the valve body head 20b in order to guide the pilot valve body 20 (to support it so that it can slide relative to the plunger 27). However, according to this embodiment, the valve body 20a is slidably supported by the pipe member 29, so it is no longer necessary to guide the pilot valve body 20 with the valve body head 20b as in the conventional design. Therefore, the valve body head 20b can be made smaller than in the conventional design, and manufacturing costs can be reduced.

[0050] [Second Embodiment] A solenoid valve according to a second embodiment of the present invention will be described based on Figures 6 to 10. In the following description, components similar to those in the first embodiment are denoted by the same reference numerals, and redundant explanations will be omitted, with the focus being on the differences.

[0051] As shown in Figures 6 to 10, the solenoid valve 41 according to the second embodiment of the present invention is a normally open type (normally open) pilot-operated solenoid valve that is open when not energized, similar to the first embodiment, and is equipped with a pipe member 29 that presses the main valve body 18 in the closing direction when the valve is closed, but the drive device 24 is fixed by a fixing screw 34 provided on the top surface.

[0052] Specifically, in this embodiment, the sleeve 26 is a cylindrical member without a bottom or lid (with openings on both the top and bottom surfaces), and the top opening of the sleeve 26 is closed by fixing the plug-shaped member 33 to the upper surface of the sleeve 26. The plug-shaped member 33 has a female screw hole on its upper surface, and the upper plate portion 35 of the housing of the drive unit 24 is fixed to the plug-shaped member 33 using a fixing screw (male screw) 34 that screws into this female screw hole, thereby fixing the drive unit 24 to the valve body 12 via the plug-shaped member 33, the sleeve 26, and the suction element member 28.

[0053] Furthermore, the lower end of the plug-shaped member 33 is inserted into the peripheral wall portion 27b of the plunger 27 from above. By the lower end of the plug-shaped member 33 facing the peripheral wall portion 27b, a part of the magnetic path is formed between the lower end and the peripheral wall portion 27b. The lower end of the plug-shaped member 33 is not in contact with the inner peripheral surface of the peripheral wall portion 27b, and there is a gap between it and the peripheral wall portion 27b. In addition, the lower surface of the plug-shaped member 33 is provided with a stopper member 36. This stopper member 36 functions to stop the upward movement of the plunger 27 by bringing it into contact with the pilot valve body 20 during the valve opening operation, and is made of an elastic material (for example, resin or rubber) to reduce collision noise.

[0054] In this embodiment, the pilot valve body 20 is provided with a projection 20c extending upward from the center of the upper surface of the valve body head 20b, and the upper end of this projection 20c abuts against the stopper member 36. In this embodiment, the pilot valve body pressing spring 30, which presses the pilot valve body 20 downward, is positioned between the valve body head 20b and the stopper member 36.

[0055] The opening and closing operation of the solenoid valve 41 according to this embodiment is the same as that of the solenoid valve 11 according to the first embodiment, except that the rising plunger 27 is stopped when the pilot valve body 20 (protruding portion 20c) comes into contact with the stopper member 36 during the valve opening operation.

[0056] That is, when current is supplied to the coil 25 from the open valve state (non-driven state of the drive device 24) as shown in Figures 6 and 7, the plunger 27 descends together with the pilot valve body 20 and pipe member 29 against the biasing force of the plunger return spring 31 due to the suction force of the suction member 28, and the pilot passage 21 is closed by the pilot valve body 20 as shown in Figure 8. In response to this closing of the pilot valve, the main valve body 18 descends against the biasing force of the main valve opening spring 32 and seats on the main valve seat 17 as shown in Figure 9, closing the main valve opening 16. Furthermore, the plunger 27 and pipe member 29 descend due to the suction force of the suction member 28, and as shown in Figure 10, the pipe member 29 comes into contact with the main valve body 17b and presses the main valve body 18 in the closing direction.

[0057] Furthermore, when the current to the coil 25 is stopped from the closed valve state, the plunger 27 is lifted by the biasing force of the plunger return spring 31 against the biasing force of the pilot valve body pressing spring 30, the pilot valve body 20 is pulled up and the pilot passage 21 is opened. In response to this opening of the pilot valve, the main valve body 18 rises, and the main valve opening 16 is opened, resulting in an open valve state (see Figures 6 and 7). Also, in this opening operation, the rising plunger 27 is stopped when the protruding portion 20c of the pilot valve body 20 comes into contact with the stopper member 36, and does not come into contact with the plug-shaped member 33.

[0058] The solenoid valve 41 of this embodiment also has the same advantages (1) to (5) as the solenoid valve 11 of the first embodiment. On the other hand, in this embodiment, as described above, when the plunger 27 returns upward in the valve opening operation, the pilot valve body 20 comes into contact with the stopper member 36, stopping the plunger 27. Therefore, the plunger 27 does not collide with the sleeve 26 or the plug-shaped member 33 as in the solenoid valve 11 of the first embodiment. Thus, according to this embodiment, not only the collision noise during the valve closing operation but also the collision noise during the valve opening operation can be reduced.

[0059] In the first and second embodiments described above, the pipe member 29, which serves as the pressing portion, is a separate component from the plunger 27 and is fixed to the plunger 27. In other examples, the pressing portion may be formed integrally with the plunger 27. Integral here means that the plunger 27 and the pressing portion are a single component. That is, the pressing portion is not a separate component from the plunger 27. An example of this pressing portion is cylindrical in shape, having the same appearance as the pipe member 29.

[0060] Furthermore, in the first and second embodiments described above, one example of a configuration in which the pressing portion (pipe member 29) is used in a normally open type pilot-operated solenoid valve 11, 41 was explained. In other examples, the pressing portion 29 may be used in a normally closed type pilot-operated solenoid valve that is open when energized.

[0061] Furthermore, in the first and second embodiments described above, a configuration in which the pipe member 29 is fixed to the plunger 27 was described as an example, but in other examples, the pipe member 29 may be indirectly fixed to the plunger 27 via other members. In this example, the pipe member 29 may be fixed to the plunger 27 via a spring. The spring is, for example, a coil spring, and is arranged so that its expansion and contraction directions are along the valve opening direction (away from the main valve body) and the valve closing direction (towards the main valve body).

[0062] A third embodiment of the present invention will be described below with reference to the drawings. However, the present invention is not limited to this embodiment. Furthermore, in the drawings, the same parts are denoted by the same reference numerals. In this specification, "upper" refers to the plunger side, and "lower" refers to the aspirator side.

[0063] (Configuration of the Solenoid Valve) First, the overall configuration of the solenoid valve according to this embodiment will be described with reference to Figure 12. Figure 12 is a longitudinal cross-sectional view showing an example of the configuration of the solenoid valve of this embodiment. Here, L indicates the axis of the solenoid valve 101. As shown in Figure 12, the solenoid valve 101 includes a valve body 1010, an suction element 1040, a plunger 1050, a pilot valve body 1060, a main valve body 1070, and an electromagnetic drive device 1080.

[0064] The valve body 1010 has a block-shaped main body portion 1011, within which an inlet passage 1012 and an outlet passage 1013 are formed opposite each other, and a circular opening 1014 is formed in the center of the main body portion 1011, with their axes intersecting. The inner end of the inlet passage 1012, to which piping (not shown) is connected, communicates with the inner end of the circular opening 1014. The inner side of the outlet passage 1013, to which piping (not shown) is connected, is bent in an L-shape, and its cylindrical end portion 1013a protrudes coaxially into the circular opening 1014. The upper end of the cylindrical end portion 1013a becomes the main valve opening 1013b.

[0065] The upper surface of the main body 1011 is flat perpendicular to the axis L. A circular opening 1014 is formed on the upper surface coaxial with the axis L. A screw hole (not shown) in the shape of a blind hole is formed on either side of the circular opening 1014.

[0066] A suction element 1040 is installed inside the circular opening 1014. The suction element 1040 consists of a disc-shaped base 1041 and a shaft portion 1042 having a smaller diameter than the base 1041, connected coaxially. The base 1041 has a circular opening 1041a formed in the center of its lower end. A hole 1041b is formed spanning the base 1041 and the shaft portion 1042, communicating with the center of the opening 1041a and opening towards the upper end.

[0067] Within the opening 1041a, the main valve body 1070 is slidably positioned along the axis L, and its lower surface is seatable on the main valve port 1013b. A pilot passage 1076 is formed in the center of the main valve body 1070, penetrating vertically, and a pilot valve port 1071 opens at the upper end of the pilot passage 1076. Adjacent to the pilot valve port 1071, a pressure equalization passage 1072 is formed, penetrating vertically. The main valve body 1070 is biased upward (towards the shaft portion 1042) relative to the base portion 1041 of the suction element 1040 by a lower spring (first coil spring) 1073. In this embodiment, the lower spring 1073 is supported by the suction element 1040, but it may also be supported by the valve body 1010.

[0068] The male threads formed on the outer circumference of the base portion 1041 are screwed into the female threads on the inner circumference of the circular opening 1014, thereby fixing the suction element 1040 to the main body portion 1011 of the valve body 1010, with its lower end outer circumference in contact with the inner circumferential step of the circular opening 1014. At this time, an O-ring OR is placed between the base portion 1041 and the circular opening 1014 to prevent fluid leakage from the gap between them.

[0069] With the base portion 1041 attached to the circular opening 1014, the shaft portion 1042 protrudes upward. The lower end of a thin-walled, top-cylindrical sleeve 1044 is joined coaxially to the upper end of the shaft portion 1042 by welding or brazing. Inside the sleeve 1044 are a plunger 1050 and a pilot valve body 1060.

[0070] The plunger 1050, which has a hollow cylindrical shape, is slidably positioned relative to the sleeve 1044 in the axial direction L. The pilot valve body 1060 consists of, from top to bottom, an engaging portion 1061, a needle portion 1062 having a smaller diameter than the engaging portion 1061, and a valve portion 1063 formed at the lower end of the needle portion 1062. In this embodiment, the valve portion 1063 has a shape in which the cross-sectional area decreases towards its tip (lower end in the figure). The needle portion 1062 is an example of a shaft portion as referred to in this invention.

[0071] A reduced-diameter portion, the engaged portion 1053, is formed on the intermediate inner circumference of the plunger 1050. With the pilot valve body 1060 assembled inside the plunger 1050, the engaged portion 1061 is locked to the engaged portion 1053 of the plunger 1050, thereby holding the pilot valve body 1060 relative to the plunger 1050. In this state, the needle portion 1062 of the pilot valve body 1060 protrudes downward from the plunger 1050 and is inserted into the hole 1041b of the shaft portion 1042 of the suction element 1040, and the valve portion 1063 further protrudes into the opening 1041a and faces the pilot valve port 1071 of the main valve body 1070.

[0072] An upper spring (third coil spring) 1051 is positioned between the top of the plunger 1050 and the engaging portion 1061 of the pilot valve body 1060, biasing the pilot valve body 1060 downward. The upper spring 1051 has a roughly trumpet shape with an outer cross-section that opens upward, its upper end supported by a groove 1054 formed on the top of the plunger 1050, and its lower end supported by the engaging portion of the pilot valve body 1060. The upper part of the plunger 1050 includes a shape that opens upward toward the groove 1054, following the outer shape of the upper spring 1051. In addition, a middle spring (second coil spring) 1052 is positioned between the engaged portion 1053 of the plunger 1050 and the upper part of the main valve body 1070, biasing the plunger 1050 upward and the main valve body 1070 downward.

[0073] The electromagnetic drive device 1080 includes a hollow cylindrical electromagnetic coil 1081, a housing 1082 attached to the electromagnetic coil 1081, and a connector (not shown) for supplying power to the electromagnetic coil 1081.

[0074] The housing 1082 is formed by press-forming a metal sheet into a roughly C-shape, and consists of an upper plate, a lower plate, and a side plate connected together by bending them at approximately 90° (more precisely, less than 90°) along their respective connecting lines. The side plate connects the ends of the upper plate and the lower plate that overlap in the vertical direction, and its length in the axial direction L is approximately equal to the height of the electromagnetic coil 1081. The upper plate has an upper hole through which the sleeve 1044 can pass.

[0075] (Operation of the Solenoid Valve) Next, the operation of the solenoid valve of this embodiment will be described with reference to Figures 13 and 14. Figure 13 is a diagram showing the closed state of the solenoid valve of this embodiment.

[0076] In Figure 13, when power is supplied to the electromagnetic coil 1081 from the power source via a connector (not shown), the magnetic field generated by the electromagnetic coil 1081 creates a magnetic path through the plunger 1050, the attractor 1040, and the housing 1082, generating a magnetic force that pushes down the plunger 1050 against the biasing force of the central spring 1052. When the plunger 1050 is pushed down, the pilot valve body 1060 descends, blocking the pilot valve port 1071 of the main valve body 1070 and pushing down the main valve body 1070 to close the main valve port 1013b.

[0077] In this state, the pressure in the upper space (pilot valve chamber 1074) of the main valve body 1070, which communicates with the inlet passage 1012 via the pressure equalization passage 1072, becomes greater than the internal pressure of the cylindrical end portion 1013a, which communicates with the outlet passage 1013. In addition, the lower end of the intermediate spring 1052 directly biases the upper part of the main valve body 1070 downwards, so the main valve body 1070 seats in the main valve opening 1013b and the valve is maintained closed.

[0078] Here, even when there is almost no pressure difference between the main valve chamber 1075 and the pilot valve chamber 1074, the main valve body 1070 is reliably closed. To achieve this, the installation load of the middle spring 1052 when the valve is closed should be set to exceed the installation load of the lower spring 1073. This ensures that the fluid flow from the inlet passage 1012 to the outlet passage 1013 is reliably blocked.

[0079] Figure 14 shows the open state of the solenoid valve in this embodiment. When the power supply from the power source to the electromagnetic coil 1081 is interrupted, the magnetic force pushing down the plunger 1050 disappears, and the plunger 1050 is pushed up by the intermediate spring 1052, causing the pilot valve body 1060 to rise and move away from the main valve body 1070, opening the pilot valve port 1071. As a result, fluid flows from the pilot chamber, which is the space between the suction element 1040 and the main valve body 1070, to the outflow passage 1013 via the pilot valve port 1071. The differential pressure between the upper space of the main valve body 1070 (pilot valve chamber 1074) and the main valve chamber 1075 (more precisely, the differential pressure between the outer peripheral space of the cylindrical end 1013a and the projected portion of the outer peripheral space of the pilot valve chamber 1074) causes the main valve body 1070 to rise, creating a gap between it and the main valve port 1013b, and opening the valve.

[0080] In this state, fluid flows from the inlet passage 1012 to the outlet passage 1013 through the cylindrical end 1013a. The pressure in the outer circumferential space of the cylindrical end 1013a is closer to that of the inlet passage 1012 than to that of the outlet passage 1013, while the pressure in the inner circumferential space of the cylindrical end 1013a and the pilot valve chamber 1074 is closer to that of the outlet passage 1013 than to that of the inlet passage 1012.

[0081] Here, in order to ensure that the main valve body 1070 is reliably opened against the intermediate spring 1052 that directly biases the main valve body 1070, when the valve is open (not energized) and the plunger 1050 is in direct or indirect contact with the sleeve 1044 and moving in the axial direction, the installation load of the lower spring 1073 should be set to exceed the installation load of the intermediate spring 1052. Indirect contact here means that the plunger 1050 contacts the sleeve 1044 via another member. In this embodiment, since the upper spring 1051 is supported by the groove 1054 at the upper end of the plunger, there is no problem in considering the installation load of the upper spring 1051 when the valve is open. This ensures that the fluid flow from the inlet passage 1012 to the outlet passage 1013 is reliably guaranteed.

[0082] In this embodiment, instead of the conventional configuration in which the lower end of the intermediate spring 10152 was supported by contact with the suction element 10140, the lower end of the intermediate spring 1052 is extended to the upper part of the main valve body 1070 and positioned at the upper part of the main valve body 1070. As a result, even in a state of slight differential pressure where there is almost no pressure difference between the main valve chamber 1075 and the pilot valve chamber 1074, the main valve body 1070 can be reliably pressed against the main valve opening 1013b, thereby suppressing valve leakage.

[0083] (Assembly of the Solenoid Valve) Next, the assembly of the solenoid valve of this embodiment will be described with reference to Figure 15. Figure 15 is a diagram showing a comparison of the assembly of the solenoid valve of this embodiment and the solenoid valve of the comparative example. Figure 15(a) shows an outline of the assembly of the solenoid valve of the comparative example, and Figure 15(b) shows an outline of the assembly of the solenoid valve of this embodiment.

[0084] As shown in Figure 15(a), in the comparative example solenoid valve, when assembling the sleeve 10144 to the suction element 10140, the upper spring 10151, plunger 10150, and pilot valve body 10160 are set inside the sleeve 10144, and then the sleeve 10144 is joined to the shaft portion 10142 of the suction element 10140 with the middle spring 10152 interposed between it and the suction element 10140.

[0085] In the comparative example solenoid valve, the middle spring 10152 is positioned between the suction element 10140 and the plunger 10150, so the middle spring 10152 must be assembled together with the plunger 10150 in an unstable position. Furthermore, when joining the sleeve 10144 to the suction element 10140, both the upper spring 10151 and the middle spring 10152 exert a biasing force in the opposite direction to the joining direction. Therefore, when assembling the sleeve 10144 to the suction element 10140, a complex jig is required to guide the sleeve 10144 relative to the suction element 10140.

[0086] In contrast, as shown in Figure 15(b), in this embodiment, the intermediate spring 1052 is positioned between the sleeve 1044 and the main valve body 1070. Therefore, when joining the sleeve 1044 to the suction element 1040, the intermediate spring 1052 does not need to be assembled to the suction element 1040 together with the plunger 1050. It can be assembled separately from below after the sleeve 1044 and the suction element 1040 have been joined, making assembly easy.

[0087] Furthermore, in this embodiment, since the upper end of the upper spring 1051 is supported by the groove 1054 formed in the sleeve 1044, the upper spring 1051 and the middle spring 10152 do not exert a biasing force when joining the sleeve 1044 to the suction element 1040, thus simplifying the design.

[0088] Thus, the solenoid valve of this embodiment also makes it possible to improve the ease of assembly of the solenoid valve.

[0089] (Modifications) Although a third embodiment of the present invention has been described above, the present invention is not limited to the third embodiment described above, and various modifications are possible without departing from the spirit of the present invention.

[0090] For example, the solenoid valve 101 of the third embodiment is configured to support the upper end of the upper spring 1051 with a plunger 1050, but it is not limited to this, and it is also possible to support it with a sleeve 1044, similar to the conventional solenoid valve 10101. In this case, the main valve body 1070 is biased downward by the combined force of the middle spring 1052 and the upper spring 1051, so in order to ensure that the main valve body 1070 is opened, it is preferable to set the installation load of the lower spring 1073 when the valve is open to be greater than the sum of the installation loads of the middle spring 1052 and the upper spring 1051.

[0091] Furthermore, in the solenoid valve 101 of the third embodiment, the outer cross-section of the upper spring 1051 is made into a roughly trumpet shape that opens upward, and its upper end is directly supported by the groove 1054 formed in the plunger 1050. However, it is not limited to this, and it may be indirectly supported using another component such as a washer. It is also possible to make the outer shape of the upper spring 1051 into a roughly cylindrical shape, and to support its upper end directly or indirectly using another component such as a washer on the plunger 1050 or sleeve 1044.

[0092] Furthermore, although the solenoid valve 101 of the third embodiment is configured to include an upper spring 1051, it is not limited to this configuration, and the upper spring 1051 can be omitted in cases such as when the stroke of the main valve body is short.

[0093] Furthermore, the solenoid valve 101 of the third embodiment is constructed with a block-shaped main body portion 1011 as the valve body 1010, and an inlet passage 1012 and an outlet passage 1013 arranged opposite each other within the main body portion 1011, and a circular opening 1014 formed in the center of the main body portion 1011, with their axes intersecting, the inner end of the inlet passage 1012 communicating with the inner end of the circular opening 1014, and the inner side of the outlet passage 1013 is bent into an L shape so that its cylindrical end portion 1013a protrudes coaxially into the circular opening 1014. However, the invention is not limited to this, and a cartridge type is also possible.

[0094] Figure 16 shows an example of a cartridge-type solenoid valve. The configuration of the solenoid valve 102 shown in Figure 16 will be explained below, but since the configuration is the same as that of the solenoid valve 101 shown in Figure 12, except for the valve body 1020, the explanation will be omitted.

[0095] The valve body 1020 of the solenoid valve 102 has an inlet passage 1022 and an outlet passage 1023 formed within the main body portion 1021, with their respective axes intersecting. The axis of the inlet passage 1022 intersects with a circular opening 1024 formed in the center of the main body portion 1021, and the inner end of the inlet passage 1022 is in communication with the inner end of the circular opening 1024. The outlet passage 1023 has a cylindrical end portion 1023a formed coaxially with the circular opening 1024. The inner end of the cylindrical end portion 1023a protrudes into the circular opening 1024, forming a main valve opening 1023b, and the outer end opens downward.

[0096] Furthermore, this specification also includes the disclosure of the following invention: (First aspect) A solenoid valve comprising: a valve body having a main valve chamber and a pilot valve chamber inside, and having an inlet passage through which fluid flows into the main valve chamber and an outlet passage through which the fluid flows out of the main valve chamber, and having a main valve port formed at the end of the outlet passage on the main valve chamber side; a main valve body that opens and closes the main valve port by moving back and forth relative to the main valve port; a pilot passage that penetrates the main valve body and connects the pilot valve chamber and the outlet passage; a pressure equalizing passage that connects the main valve chamber and the pilot valve chamber; a pilot valve port formed at the end of the pilot passage on the pilot valve chamber side; a pilot valve body that opens and closes the pilot passage by moving back and forth relative to the pilot valve port; a plunger connected to the pilot valve body so as to be axially movable, and an electromagnetic drive device that drives the pilot valve body, including a suction element for attracting the plunger; A solenoid valve characterized by having a pressing portion provided on the plunger that, when the main valve body is in a closed state, contacts a portion of the main valve body different from the portion that the pilot valve body contacts, thereby pressing the main valve body in the closing direction. (Second embodiment) The solenoid valve according to the first embodiment, wherein the pressing portion moves integrally with the plunger in the axial direction. (Third embodiment) The solenoid valve according to the first embodiment, wherein, when the main valve body is in a closed state, the pressing portion contacts the surface of the main valve body around the pilot valve port, and the surface is made of one of resin, rubber, and elastomer. (Fourth embodiment) The solenoid valve according to the third embodiment, wherein, when the valve is closed, the plunger does not contact the suction element, and a gap is formed between the plunger and the suction element.(Fifth embodiment) A solenoid valve according to any one of the first to fourth embodiments, comprising: a plunger return spring that biases the plunger away from the main valve body; and a pilot valve body pressing spring that biases the pilot valve body toward the main valve body, wherein the plunger and the pilot valve body are connected by contact such that they press against each other in the axial direction due to the biasing force of the plunger return spring and the biasing force of the pilot valve body pressing spring, and are relatively movable against the biasing force of the plunger return spring or the biasing force of the pilot valve body pressing spring, and the pressing portion moves toward the main valve body together with the plunger even after the relative movement between the pilot valve body and the main valve body stops when the pilot valve body comes into contact with the pilot valve port during valve closing operation. (Sixth aspect) The solenoid valve according to the fifth aspect, wherein the plunger return spring is made of a coil spring, and the pressing portion is cylindrical, with a part of its axial direction located inside the plunger return spring and along the inner circumferential surface of the plunger return spring. (Seventh aspect) The solenoid valve according to the first aspect, comprising a stopper member made of an elastic material, which the pilot valve body abuts against when the valve is opened, and the plunger, which moves away from the main valve body when the valve is opened, stops when the pilot valve body abuts against the stopper member. (Eighth aspect) The solenoid valve is a normally open type solenoid valve, the electromagnetic drive device comprises a sleeve for housing the plunger and the pilot valve body, the suction element is fixed to the valve body and has a hole in which the pilot valve body is disposed, and comprises a first coil spring having one end supported by the valve body or the suction element and the other end supported by the main valve body, which biases the main valve body in a direction away from the main valve opening, and a second coil spring disposed in the hole of the suction element, having one end supported by the plunger and the other end supported by the main valve body, which serves as the pressing part.(Ninth aspect) The solenoid valve according to the eighth aspect, wherein the pilot valve body has a shaft portion including a valve portion for opening and closing the pilot valve port, and an engaging portion formed at the other end of the shaft portion with respect to the valve portion, the plunger is cylindrical in shape with the pilot valve body disposed inside, and has an engaged portion on its inner surface that restricts the movement of the pilot valve body toward the closed side by engaging with the engaging portion, and further comprises a third coil spring for biasing the pilot valve body toward the suction element, the third coil spring having one end supported by the engaging portion and the other end supported by the plunger. (Tenth aspect) The solenoid valve according to the eighth or ninth aspect, wherein the first coil spring and the second coil spring have an installation load set such that they open the main valve port when not energized and the plunger's axial movement is restricted by the sleeve. (Eleventh embodiment) The solenoid valve according to the eighth embodiment, wherein the pilot valve body has a shaft portion including a valve portion for opening and closing the pilot valve port, and an engaging portion formed at the other end of the shaft portion with respect to the valve portion, the plunger is cylindrical in shape with the pilot valve body disposed inside, and has an engaged portion on its inner surface that restricts the movement of the pilot valve body toward the closed side by engaging with the engaging portion, and further comprises a third coil spring for biasing the pilot valve body toward the suction element, the third coil spring having one end supported by the engaging portion and the other end supported by the sleeve. (Twelfth embodiment) The solenoid valve according to the eleventh embodiment, wherein the first coil spring, the second coil spring and the third coil spring are set to have an installation load such that they open the main valve port when the plunger is not energized and its axial movement is restricted by the sleeve. (13th embodiment) The solenoid valve according to the 8th embodiment, wherein the valve body has a circular opening in the center, the inlet passage has an axis that intersects with the axis of the circular opening and its inner end communicates with the inner end of the circular opening, and the outlet passage is formed coaxially with the circular opening, its inner end protruding into the circular opening and its outer end opening downward.

[0097] A Axis (central axis) F Refrigerant flow G Air gap 11, 41 Solenoid valve 12 Valve body 13 Main valve chamber 14 Inlet passage 15 Outlet passage 16 Main valve port 17 Main valve seat 18 Main valve body 18a Main valve outer circumference 18b Main valve body 19 Pilot valve chamber 20 Pilot valve body 20a Valve body 20b Valve body head 20c Protrusion 21 Pilot passage 22 Pilot valve port 23 Pressure equalization passage 24 Electromagnetic drive device (drive device) 25 Coil 26 Sleeve 27 Plunger 27a Bottom of plunger 27b Peripheral wall of plunger 28 Suction element member 28a Suction element body 28b Connection part 28c Center hole of suction element body 28d Center hole of connection part (main valve body guide part) 29 Pipe member 30 Pilot valve body pressing spring 31 Plunger return spring 32 Main valve opening spring 33 Plug-shaped member 33a Guide part 34 Fixing screw 35 Upper plate part of housing 36 Stopper member 101, 102, 10101 Solenoid valve 1010, 1020 Valve body 1011, 1021 Body part 1012, 1022 Inlet passage 1013, 1023 Outlet passage 1013a, 1023a, 10113a Cylindrical end 1013b, 1023b, 10113b Main valve opening 1014, 1024 Circular opening 1040, 10140 Suction element 1041 Base part 1041a Opening 1041b Hole 1042, 10142 Shaft section 1044, 10144 Sleeve 1050, 10150 Plunger 1051, 10151 Upper spring (third coil spring) 1052, 10152 Middle spring (second coil spring) 1053 Engaged section 1054 Groove section 1060, 10160 Pilot valve body 1061 Engaged section 1062 Needle section (shaft section) 1070, 10170 Main valve body 1071, 10171 Pilot valve port 1072, 10172 Pressure equalizing passage 1073, 10173 Lower spring (first coil spring) 1074, 10174 Pilot valve chamber 1075, 10175 Main valve chamber 1076 Pilot passage 1080 Electromagnetic drive device 1081, 10181 Electromagnetic coil 1082, 10182 Housing

Claims

1. A solenoid valve comprising: a valve body having a main valve chamber and a pilot valve chamber inside, an inlet passage through which fluid flows into the main valve chamber and an outlet passage through which the fluid flows out of the main valve chamber, and a main valve port formed at the end of the outlet passage on the main valve chamber side; a main valve body that opens and closes the main valve port by moving back and forth relative to the main valve port; a pilot passage that penetrates the main valve body and connects the pilot valve chamber and the outlet passage; a pressure equalization passage that connects the main valve chamber and the pilot valve chamber; a pilot valve port formed at the end of the pilot passage on the pilot valve chamber side; a pilot valve body that opens and closes the pilot passage by moving back and forth relative to the pilot valve port; a plunger connected to the pilot valve body so as to be axially movable, and an electromagnetic drive device that drives the pilot valve body, including a suction element that attracts the plunger; A solenoid valve characterized by having a pressing portion provided on or supported by the plunger, which, when the main valve body is in a closed state, contacts a portion of the main valve body different from the portion that the pilot valve body contacts, thereby pressing the main valve body in the closing direction.

2. The solenoid valve according to claim 1, wherein the pressing portion moves integrally with the plunger in the axial direction.

3. The solenoid valve according to claim 1, wherein the pressing portion contacts the surface of the main valve body around the pilot valve port when the main valve body is closed, and the surface is made of one of resin, rubber, and elastomer.

4. The solenoid valve according to claim 3, wherein, in the closed valve state, the plunger does not contact the suction element, and a gap is formed between the plunger and the suction element.

5. A solenoid valve according to any one of claims 1 to 4, comprising: a plunger return spring that biases the plunger away from the main valve body; and a pilot valve body pressing spring that biases the pilot valve body toward the main valve body, wherein the plunger and the pilot valve body are connected by contact such that they press against each other in the axial direction due to the biasing force of the plunger return spring and the biasing force of the pilot valve body pressing spring, and are relatively movable against the biasing force of the plunger return spring or the biasing force of the pilot valve body pressing spring, and the pressing portion moves toward the main valve body together with the plunger even after the relative movement between the pilot valve body and the main valve body stops when the pilot valve body comes into contact with the pilot valve port during valve closing operation.

6. The solenoid valve according to claim 5, wherein the plunger return spring is made of a coil spring, and the pressing portion is cylindrical, with a portion of its axial direction located inside the plunger return spring and along the inner circumferential surface of the plunger return spring.

7. The solenoid valve according to claim 1, comprising a stopper member made of an elastic material, against which the pilot valve body abuts when the valve is opened, wherein the plunger, which moves in a direction away from the main valve body during the valve opening operation, stops when the pilot valve body abuts against the stopper member.

8. The solenoid valve is a normally open type solenoid valve, wherein the electromagnetic drive device comprises a sleeve for housing the plunger and the pilot valve body, the suction element is fixed to the valve body and has a hole in which the pilot valve body is disposed, and comprises a first coil spring with one end supported by the valve body or the suction element and the other end supported by the main valve body, which biases the main valve body in a direction away from the main valve opening, and a second coil spring disposed in the hole of the suction element, with one end supported by the plunger and the other end supported by the main valve body, which serves as the pressing part.

9. The solenoid valve according to claim 8, wherein the pilot valve body has a shaft portion including a valve portion for opening and closing the pilot valve port, and an engaging portion formed at the other end of the shaft portion with respect to the valve portion, the plunger is cylindrical in shape with the pilot valve body disposed inside, and has an engaged portion on its inner surface that restricts the movement of the pilot valve body toward the closed side by engaging with the engaging portion, and further comprises a third coil spring for biasing the pilot valve body toward the suction element, the third coil spring having one end supported by the engaging portion and the other end supported by the plunger.

10. The solenoid valve according to claim 8 or 9, wherein the first coil spring and the second coil spring are set to have an installation load such that they open the main valve port when the plunger is not energized and its axial movement is restricted by the sleeve.

11. The solenoid valve according to claim 8, wherein the pilot valve body has a shaft portion including a valve portion for opening and closing the pilot valve port, and an engaging portion formed at the other end of the shaft portion with respect to the valve portion, the plunger is cylindrical in shape with the pilot valve body disposed inside, and has an engaged portion on its inner surface that restricts the movement of the pilot valve body toward the closed side by engaging with the engaging portion, and further comprises a third coil spring for biasing the pilot valve body toward the suction element, the third coil spring having one end supported by the engaging portion and the other end supported by the sleeve.

12. The solenoid valve according to claim 11, wherein the first coil spring, the second coil spring, and the third coil spring are set to have an installation load such that they open the main valve port when the plunger is not energized and its axial movement is restricted by the sleeve.

13. The solenoid valve according to claim 8, wherein the valve body has a circular opening in the center, the inlet passage has an axis that intersects with the axis of the circular opening and its inner end communicates with the inner end of the circular opening, and the outlet passage is formed coaxially with the circular opening, its inner end protruding into the circular opening and its outer end opening downward.

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