Electric valve and refrigeration cycle system

Abstract

The present invention provides an electric valve and a refrigeration cycle system. In an electric valve that controls the flow rate in a small flow rate control region and a large flow rate control region, in the large flow rate control region, the fully open position of the main valve element 3 is set at a predetermined position to stabilize the fully open flow rate, and vibration of the main valve element 3 is prevented, and noise is also prevented. It includes a main valve element (3) that opens and closes the main valve port (13a), a needle valve (4) that changes the opening degree of the sub-valve port (33a) of the sub-valve chamber (3R) of the main valve element (3), a main valve spring (35) that applies a force to the main valve element (3) toward the main valve port (13a) side, and a drive unit (5) that drives the needle valve (4) to move forward and backward along the axis (L) direction. A D-shaped cut surface (3a) is formed on the holding portion (32) of the main valve element (3), and a drain passage (10) that communicates the back pressure chamber (2R) with the main valve chamber (1R) with respect to the main valve element (3) is provided.

Description

[0001] This invention is a divisional application of the invention application with the application number 202010214506.8, the invention title "Electric valve and refrigeration cycle system", and the application date of March 24, 2020. Technical Field

[0002] The present invention relates to an electric valve used in a refrigeration cycle system and the like, and a refrigeration cycle system. Background Art

[0003] Conventionally, as an electric valve provided in the refrigeration cycle of an air conditioner, there is an electric valve that controls the flow rate in a small flow rate control region and a large flow rate control region. Such an electric valve is used for indoor units (for example, a dehumidification valve), and is disclosed in, for example, Japanese Patent Laid-Open No. 2000-227165 (Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 2000-227165 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the existing electric valve (electric control valve) of Patent Document 1, a main valve core is disposed opposite to a large-diameter port (main valve port) on the secondary joint pipe side, the main valve core is guided by a sleeve member, and a back pressure chamber is defined between the valve housing (cover member) and the main valve core. In addition, a compression coil spring provided between the pilot valve core and the main valve core applies a force to the main valve core toward the main valve port side. Further, the opening degree of a pilot port (small-diameter port) provided in the main valve core is controlled by the pilot valve core as a small flow rate control region. Although not described in detail in Patent Document 1, such an electric valve is used as a dehumidification valve in a refrigeration cycle system in an indoor unit, and has a structure in which the large-diameter port is opened by raising the main valve core, and for example, in a large flow rate control region during heating operation, a large flow rate of fluid (refrigerant) flows from the large-diameter port side.

[0009] However, in such a state of the large flow rate control region during heating operation, the pressure of the fluid flowing in from the large-diameter port raises the main valve core, but due to the action of this pressure and the main valve spring load, vibration occurs in the main valve core, and due to the deviation of the fully open position of the main valve core, the fully open flow rate during heating operation deviates, making it difficult to perform stable control. In addition, there are problems such as noise generated due to the vibration of the main valve core.

[0010] An object of the present invention is to prevent vibration of a main valve element in a large flow control region, stabilize it at a fully open position and stabilize the fully open flow rate, and prevent noise in an electric valve that performs flow control in a small flow control region and a large flow control region.

[0011] Means for Solving the Problem

[0012] The electric valve of the present invention includes: a valve housing that houses a main valve chamber therein; and an outer housing that is joined to the upper portion of the valve housing and houses a magnetic rotor therein. A first joint pipe for fluid inlet and outlet that opens to the main valve chamber is provided on the side surface of the valve housing, and a second joint pipe for fluid inlet and outlet that is connected to a main valve port provided at the lower portion of the valve housing is provided. The electric valve includes: a main valve element that opens and closes the main valve port of the main valve chamber; a sub-valve element that changes the opening degree of a sub-valve port of a sub-valve chamber provided in the main valve element; a main valve spring that biases the main valve element from the back pressure chamber side of the main valve element toward the main valve port side; and a drive unit that drives the sub-valve element to advance and retreat in the axial direction, and has a two-stage flow control region including a small flow control region and a large flow control region. In the small flow control region, the sub-valve element is slidably inserted in a sub-valve guide hole of the main valve element in the axial direction, and in a state where the main valve element closes the main valve port, the sub-valve element changes the opening degree of the sub-valve port. In the large flow control region, the main valve element keeps the main valve port in a fully open state, and allows a large flow rate of fluid flowing in from the main valve port to flow from the main valve chamber to a side port. The electric valve is characterized in that it includes a pressure discharge path that communicates the back pressure chamber with the main valve chamber and has an opening area larger than the cross-sectional area of the gap between the main valve element and the sub-valve element in the sub-valve guide hole that is orthogonal to the axis.

[0013] According to the present invention, even if high-pressure fluid from the main valve port side flows into the back pressure chamber through the gap between the main valve element and the sub-valve guide hole, the high-pressure fluid in the back pressure chamber can be discharged to the main valve chamber through the pressure discharge path. In addition, since the opening area of the pressure discharge path is larger than the cross-sectional area of the gap, the high-pressure fluid in the back pressure chamber can be quickly discharged to the main valve chamber. Therefore, if the pressure in the back pressure chamber is too high, it is difficult for the main valve element to compress the main valve spring, the behavior of the main valve element becomes unstable and vibration occurs. However, according to the present invention, since the high-pressure fluid in the back pressure chamber can be quickly discharged to the main valve chamber, the main valve spring can be quickly brought into a stable compressed state, vibration of the main valve element can be prevented in the large flow control region to stabilize the fully open position, stabilize the fully open flow rate, and prevent noise caused by vibration.

[0014] Moreover, it is preferable to include a guiding member that inserts the main spool valve into the main valve guiding hole to guide the main spool valve in the axial direction, and the pressure discharge path is formed between the D-shaped cutting surface on the side of the main spool valve and the inner peripheral surface of the main valve guiding hole.

[0015] Moreover, it is preferable to include a guiding member that inserts the main spool valve into the main valve guiding hole to guide the main spool valve in the axial direction, and the pressure discharge path is formed by a groove parallel to the axis on the inner periphery of the main valve guiding hole.

[0016] Moreover, it is preferable to include a guiding member that inserts the main spool valve into the main valve guiding hole to guide the main spool valve in the axial direction, and the pressure discharge path is formed by a groove parallel to the axis on the outer periphery of the main spool valve.

[0017] Moreover, it is preferable to include a guiding member that inserts the main spool valve into the main valve guiding hole to guide the main spool valve in the axial direction, and the pressure discharge path is formed by the gap between the side of the main spool valve and the inner peripheral surface of the main valve guiding hole.

[0018] Moreover, it is preferable to include a guiding member that inserts the main spool valve into the main valve guiding hole to guide the main spool valve in the axial direction, and the pressure discharge path is formed by a through hole that conducts the upper part of the main valve guiding hole to the inside of the housing.

[0019] The refrigeration cycle system of the present invention includes a compressor, an indoor heat exchanger, an outdoor heat exchanger, an electronic expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger, and a dehumidifying valve provided in the indoor heat exchanger. The refrigeration cycle system is characterized in that the electric valve described in any one of the above is used as the dehumidifying valve.

[0020] In addition, the refrigeration cycle system of the present invention includes a compressor, an indoor heat exchanger, an outdoor heat exchanger, and an electronic expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger. The refrigeration cycle system is characterized in that the electric valve described in any one of the above is used as the electronic expansion valve.

[0021] According to such a refrigeration cycle system, the same effect as that of the electric valve during the heating operation can be achieved, stable control of the full-open flow rate can be performed, and a noise-proof system can be constructed.

[0022] Effects of the Invention

[0023] According to the electric valve and the refrigeration cycle system of the present invention, in an electric valve having a two-stage flow control region, the full-open flow rate of the fluid can be stabilized, and noise can be prevented. Description of the Drawings

[0024] Figure 1 is a longitudinal sectional view of the small flow control region state of the electric valve according to the first embodiment of the present invention.

[0025] Figure 2 is a longitudinal sectional view during heating operation in the fully open state of the main spool of the electric valve according to the first embodiment.

[0026] Figure 3 is a top view sectional view during heating operation in the fully open state of the main spool of the electric valve according to the first embodiment ( Figure 2 sectional view A - A of ).

[0027] Figure 4 (A) of is a longitudinal sectional view during heating operation in the fully open state of the main spool of the electric valve according to the second embodiment of the present invention, and (B) is a top view sectional view (sectional view A - A).

[0028] Figure 5 (A) of is a longitudinal sectional view during heating operation in the fully open state of the main spool of the electric valve according to the third embodiment of the present invention, and (B) is a top view sectional view (sectional view A - A).

[0029] Figure 6 (A) of is a longitudinal sectional view during heating operation in the fully open state of the main spool of the electric valve according to the fourth embodiment of the present invention, and (B) is a top view sectional view (sectional view A - A).

[0030] Figure 7 is a longitudinal sectional view during heating operation in the fully open state of the main spool of the electric valve according to the fifth embodiment of the present invention.

[0031] Figure 8 is a longitudinal sectional view during heating operation in the fully open state of the main spool of the electric valve according to the sixth embodiment of the present invention.

[0032] Figure 9 is a diagram showing the refrigeration cycle system according to the embodiment of the present invention.

[0033] In the figure:

[0034] 1 - Valve housing, 1R - Main valve chamber, 11 - First connection pipe, 12 - Second connection pipe, 13 - Main valve seat, 13a - Main valve port, 14 - Outer shell, L - Axis, 2 - Guide component, 2A - Main valve guide hole, 2R - Back pressure chamber, 21 - Press-in part, 22 - Upper guide part, 22a - Guide through hole, 23 - Lower guide part, 24 - Bracket part, 24a - Internal thread part, 25 - Flange part, 3 - Main valve core, 3a - D-shaped cutting surface, 3R - Sub-valve chamber, 31 - Main valve part, 32 - Holding part, 32a - Needle valve guide hole (sub-valve guide hole), 32b - Guide through hole, 33 - Sub-valve seat, 33a - Sub-valve port, 34 - Cage, 35 - Main valve spring, 4 - Needle valve (sub-valve core), 41 - Needle part, 42 - Washer, 43 - Guide projection, 5 - Driving part, 5A - Stepper motor, 5B - Thread feed mechanism, 5C - Limit mechanism, 51 - Rotor shaft, 51a - External thread part, 52 - Magnetic rotor, 52a - Protrusion, 53 - Stator coil, 10 - Discharge pressure path, 20 - Discharge pressure path, 30 - Discharge pressure path, 91 - First indoor-side heat exchanger, 92 - Second indoor-side heat exchanger, 93 - Electronic expansion valve, 94 - Outdoor-side heat exchanger, 95 - Compressor, 96 - Four-way valve, 100 - Electric valve. Detailed implementation mode

[0035] Hereinafter, an implementation mode of the electric valve and the refrigeration cycle system of the present invention will be described with reference to the accompanying drawings. Figure 1 is a longitudinal sectional view of the small flow rate control region state of the electric valve of the first implementation mode, Figure 2 is a longitudinal sectional view during heating operation in the fully open state of the main valve core of the electric valve of the first implementation mode, Figure 3 is a top sectional view during heating operation in the fully open state of the main valve core of the electric valve of the first implementation mode, and this Figure 3 is Figure 2 A - A sectional view of. In addition, the concept of "up and down" in the following description corresponds to the up and down in the Figure 1 and Figure 2 accompanying drawings. The electric valve 100 includes a valve housing 1, a guide component 2, a main valve core 3, a needle valve 4 as the "sub-valve core", and a driving part 5.

[0036] The valve housing 1 is formed into a substantially cylindrical shape, for example, from brass, stainless steel, etc., and has a main valve chamber 1R inside thereof. A first joint pipe 11 communicating with the main valve chamber 1R is connected to one side of the outer periphery of the valve housing 1, and a second joint pipe 12 is connected to a cylindrical portion extending downward from the lower end. Further, a cylindrical main valve seat 13 is formed on the main valve chamber 1R side of the second joint pipe 12 of the valve housing 1. The inside of the main valve seat 13 forms a main valve port 13a, and the second joint pipe 12 communicates with the main valve chamber 1R via the main valve port 13a. The main valve port 13a is a through hole (penetrating hole) having a cylindrical shape centered on the axis L. In addition, the first joint pipe 11 and the second joint pipe 12 are fastened to the valve housing 1 by brazing or the like.

[0037] A guide member 2 is installed at the opening at the upper end of the valve housing 1. The guide member 2 has: a press-fitting portion 21 press-fitted into the inner peripheral surface of the valve housing 1; substantially cylindrical guide portions 22, 23 having a diameter smaller than that of the press-fitting portion 21 and located above and below the press-fitting portion 21; a bracket portion 24 extending from the upper part of the upper guide portion 22; and an annular flange portion 25 provided on the outer periphery of the press-fitting portion 21. The press-fitting portion 21, the guide portions 22, 23, and the bracket portion 24 are formed as an integral resin member. In addition, the flange portion 25 is, for example, a metal plate such as brass or stainless steel, and the flange portion 25 is integrally formed with the resin press-fitting portion 21 by insert molding.

[0038] The guide member 2 is assembled to the valve housing 1 through the press-fitting portion 21 and fixed to the upper end portion of the valve housing 1 by welding via the flange portion 25. Further, in the guide member 2, a cylindrical main valve guide hole 2A coaxial with the axis L is formed inside the press-fitting portion 21 and the upper and lower guide portions 22, 23, and an internal thread portion 24a and its threaded hole coaxial with the main valve guide hole 2A are formed at the center of the bracket portion 24. And a main valve element 3 is disposed inside the lower guide portion 23 and within the main valve guide hole 2A.

[0039] The main valve element 3 has: a main valve portion 31 that seats on and disengages from the main valve seat 13; a holding portion 32 having a cylindrical needle valve guide hole 32a serving as a "sub-valve guide hole"; a sub-valve seat 33 forming the bottom of the needle valve guide hole 32a; and a retainer 34 provided at the end of the holding portion 32. In addition, a lower part of the needle valve guide hole 32a forms a sub-valve chamber 3R. A washer 42 mounted on a rotor shaft 51 described later and a guide projection 43 integrally formed with the rotor shaft 51 are inserted through the needle valve guide hole 32a of the holding portion 32, and the annular retainer 34 is fastened to the upper end of the holding portion 32 by fitting and fastening or welding or the like.

[0040] In addition, a main valve spring 35 is disposed between the cage 34 and the upper end portion of the main valve guide hole 2A, and the main valve spring 35 biases the main valve element 3 toward the main valve seat 13 (closing direction). A cylindrical sub-valve port 33a centered on the axis L is formed in the center of the sub-valve seat 33. In addition, a through-hole 32b that communicates the sub-valve chamber 3R with the main valve chamber 1R is formed in at least one part of the side surface of the holding portion 32. When the needle valve 4 as the sub-valve element opens the sub-valve port 33a, the main valve chamber 1R, the sub-valve chamber 3R, the sub-valve port 33a, and the main valve port 13a communicate with each other.

[0041] The needle valve 4 integrally includes a frustum-shaped needle portion 41, which is integrally formed with a later-described rotor shaft 51 at the lower end portion of the rotor shaft 51 and has a gradually decreasing diameter toward the front end connected to the rotor shaft 51 side. In addition, the needle valve 4 has an annular washer 42 made of a lubricious resin and mounted on the rotor shaft 51, and a guide projection 43 integrally formed with the rotor shaft 51. The washer 42 and the guide projection 43 are slidably inserted into the needle valve guide hole 32a. That is, a predetermined gap is provided between the outer periphery of the washer 42 and the inner periphery of the needle valve guide hole 32a.

[0042] The outer shell 14 is hermetically fixed to the upper end of the valve housing 1 by welding or the like, and a drive unit 5 is formed inside and outside the outer shell 14. The drive unit 5 includes a stepping motor 5A, a screw feed mechanism 5B that moves the needle valve 4 forward and backward by the rotation of the stepping motor 5A, and a limit mechanism 5C that limits the rotation of the stepping motor 5A.

[0043] The stepping motor 5A is composed of the following components: a rotor shaft 51; a magnetic rotor 52 rotatably disposed inside the outer shell 14; a stator coil 53 disposed opposite to the magnetic rotor 52 on the outer periphery of the outer shell 14; and other yokes, exterior components, etc. not shown. The rotor shaft 51 is installed at the center of the magnetic rotor 52 via a bushing, and an external thread portion 51a is formed on the outer periphery of the rotor shaft 51 on the guide member 2 side. The external thread portion 51a is threadedly engaged with the internal thread portion 24a of the guide member 2, whereby the guide member 2 supports the rotor shaft 51 on the axis L. The internal thread portion 24a of the guide member 2 and the external thread portion 51a of the rotor shaft 51 constitute the screw feed mechanism 5B.

[0044] According to the above structure, when the stepping motor 5A is driven, the magnetic rotor 52 and the rotor shaft 51 rotate, and through the thread feed mechanism 5B of the external thread portion 51a of the rotor shaft 51 and the internal thread portion 24a of the guide member 2, the rotor shaft 51 and the magnetic rotor 52 move together in the direction of the axis L. Further, the needle valve 4 moves forward and backward in the direction of the axis L, and the needle valve 4 approaches or moves away from the sub-valve port 33a. Additionally, when the needle valve 4 rises, the washer 42 engages with the cage 34 of the main valve element 3, and the main valve element 3 moves together with the needle valve 4 and leaves the main valve seat 13. Further, a protrusion 52a is formed on the magnetic rotor 52, and as the magnetic rotor 52 rotates, the protrusion 52a operates the rotation limiting mechanism 5C, thereby restricting the lowermost position and the uppermost position of the rotor shaft 51 (and the magnetic rotor 52).

[0045] In Figure 1 the small flow rate control region state, with the main valve element 3 seated on the main valve seat 13, the main valve port 13a is closed, and the opening degree of the sub-valve port 33a is controlled by the needle valve 4 to control a small flow rate. Additionally, for example, in a state where the compressor in the refrigeration cycle system stops and the fluid (refrigerant) stops, if the needle valve 4 and the main valve element 3 rise, then as Figure 2 shown, the main valve port 13a becomes fully open. Thus, during the heating operation of the refrigerant flowing in the direction of the dotted arrow in the Figure 6 refrigeration cycle system shown, a large flow rate of fluid (refrigerant) flows from the second joint pipe 12 of the electric valve 100 to the first joint pipe 11.

[0046] The main valve element 3 is disposed in the main valve guide hole 2A of the guide member 2, and the upper space of the main valve element 3 in the main valve guide hole 2A becomes a back pressure chamber 2R relative to the main valve element 3. Additionally, as Figure 2 , Figure 3 shown, a D-shaped cut surface 3a parallel to the axis L is formed at a part of the outer periphery of the holding portion 32 of the main valve element 3, and a pressure discharge path 10 that conducts the back pressure chamber 2R and the main valve chamber 1R is formed between the main valve guide hole 2A and the D-shaped cut surface 3a. The cross-sectional area of the pressure discharge path 10 perpendicular to the axis L, i.e., the opening area, is larger than the cross-sectional area of the smaller one of the gaps between the guiding protrusion 43 or the washer 42 of the needle valve 4 (sub-valve element) in the needle valve guide hole 32a (sub-valve guide hole) (referred to as the gap cross-sectional area of the needle valve portion).

[0047] And if in Figure 2In the state of , when a large flow rate of fluid flows from the second joint pipe 12 for heating operation, the high-pressure fluid flows into the back pressure chamber 2R through the gap between the guide hole 32a of the needle valve, the guide projection 43 of the needle valve 4, and the gasket 42. However, the fluid in the back pressure chamber 2R is discharged to the main valve chamber 1R through the discharge path 10. Since the cross-sectional area of the discharge path 10 is larger than the cross-sectional area of the gap of the needle valve portion, the back pressure chamber 2R does not become high pressure, but a high pressure acts on the lower part of the main valve element 3, and a pressure lower than that of the lower part of the main valve element 3 acts on the upper part of the main valve element 3 on the back pressure chamber side. Therefore, due to the pressure difference of the fluid acting on the upper and lower parts of the main valve element 3, the main valve element 3 rises against the acting force of the main valve spring 35, and the main valve spring 35 holds the position of the main valve element 3 in the direction of the axis L, that is, the fully open position, in a state where it is not completely compressed. In addition, in this embodiment, a through hole 22a that communicates the back pressure chamber 2R with the inside of the housing 14 is formed at at least one part on the side surface of the guide portion 22 of the guide member 2. In addition, as Figure 3 shown, a through hole 25a that communicates the main valve chamber 1R with the inside of the housing 14 is formed in the flange portion 25 of the guide member 2. Moreover, the back pressure chamber 2R and the main valve chamber 1R are also communicated through the through hole 22a, the inside of the housing 14, and the through hole 25a.

[0048] As described above, the main valve element 3 rises by the high-pressure fluid from the main valve port 13a side, compresses the main valve spring 35 and holds it at a predetermined position. Therefore, the fully open position of the main valve element 3 is stable at a predetermined position, and thus the flow rate (fully open flow rate) of the fluid flowing from the second joint pipe 12 to the first joint pipe 11 is stable. In addition, since the vibration of the main valve element 3 is prevented, noise can be prevented.

[0049] Figure 4 , Figure 5 and Figure 6 (A) of is a longitudinal sectional view during heating operation in the fully open state of the main valve element of the electric valve according to the second, third, and fourth embodiments of the present invention, and (B) is a top sectional view (A - A sectional view) thereof. In addition, in the following second embodiment, third embodiment, and fourth embodiment, the aspect different from the first embodiment is the structure of the discharge path. For the elements identical to those in the first embodiment, the same reference numerals are used and the repeated description is appropriately omitted. Figures 1 to 3 the same.

[0050] In Figure 4 the second embodiment, in the guide member 2, grooves parallel to the axis L are formed at two parts on the inner peripheral surface of the main valve guide hole 2A of the upper and lower guide portions 22, 23 and the press-fitting portion 21, and cuts are formed at two parts of the flange portion 25 corresponding to the grooves, thereby forming discharge paths 20, 20 that communicate the back pressure chamber 2R with the main valve chamber 1R. The cross-sectional area of the cross section of these grooves orthogonal to the axis L is larger than the cross-sectional area of the gap of the above-mentioned needle valve portion.

[0051] In this second embodiment, the high-pressure fluid also flows into the back pressure chamber 2R through the gap between the guide projection 43 of the needle valve 4 and the washer 42 via the needle valve guide hole 32a. However, the fluid in the back pressure chamber 2R is discharged to the main valve chamber 1R through the discharge pressure path 20. Therefore, similar to the first embodiment, the back pressure chamber 2R does not become high pressure, and the main valve element 3 rises due to the high-pressure fluid from the main valve port 13a side, compresses the main valve spring 35 and holds it at a predetermined position. Thus, the fully open position of the main valve element 3 is stable at a predetermined position. Therefore, the flow rate (fully open flow rate) of the fluid flowing from the second joint pipe 12 to the first joint pipe 11 is stable. In addition, since vibration of the main valve element 3 is prevented, noise can be prevented.

[0052] In Figure 5 In the third embodiment, grooves parallel to the axis L are formed at two positions on the outer peripheral surface of the main valve element 3, thereby forming discharge pressure paths 20', 20' that communicate the back pressure chamber 2R and the main valve chamber 1R. The cross-sectional area of these grooves perpendicular to the axis L is larger than the cross-sectional area of the gap of the above-mentioned needle valve portion.

[0053] In this third embodiment, the high-pressure fluid also flows into the back pressure chamber 2R through the gap between the guide projection 43 of the needle valve 4 and the washer 42 via the needle valve guide hole 32a. However, the fluid in the back pressure chamber 2R is discharged to the main valve chamber 1R through the discharge pressure path 20'. Therefore, similar to the first embodiment, the back pressure chamber 2R does not become high pressure, and the main valve element 3 rises due to the high-pressure fluid from the main valve port 13a side, compresses the main valve spring 35 and holds it at a predetermined position. Thus, the fully open position of the main valve element 3 is stable at a predetermined position. Therefore, the flow rate (fully open flow rate) of the fluid flowing from the second joint pipe 12 to the first joint pipe 11 is stable. In addition, since vibration of the main valve element 3 is prevented, noise can be prevented.

[0054] In Figure 6 In the fourth embodiment, the diameter of the inner periphery of the main valve guide hole 2A that penetrates the upper and lower guide portions 22, 23 and the press-in portion 21 in the guide member 2 is slightly larger than that in the first embodiment. A discharge pressure path 30 that communicates the back pressure chamber 2R and the main valve chamber 1R is formed between the outer periphery of the main valve guide hole 2A and the holding portion 32 of the main valve element 3.

[0055] In this fourth embodiment, the high-pressure fluid also flows into the back pressure chamber 2R through the gap between the guiding projection 43 of the needle valve 4 and the washer 42 via the needle valve guiding hole 32a. However, the fluid in the back pressure chamber 2R is discharged to the main valve chamber 1R via the pressure discharging path 30. Therefore, similar to the first embodiment, the back pressure chamber 2R does not become high-pressure, and the main valve element 3 rises due to the high-pressure fluid from the main valve port 13a side, compresses the main valve spring 35 and holds it at a predetermined position. Thus, the fully open position of the main valve element 3 is stabilized at a predetermined position, and therefore the flow rate (fully open flow rate) of the fluid flowing from the second joint pipe 12 to the first joint pipe 11 is stable. In addition, since the vibration of the main valve element 3 is prevented, noise can be prevented.

[0056] Figure 7 and Figure 8 FIG. is a longitudinal sectional view during the heating operation in the fully open state of the main valve element of the electric valve according to the fifth and sixth embodiments of the present invention. In addition, in the following fifth and sixth embodiments, the aspect different from the first embodiment is the structure of the pressure discharging path. For the elements the same as those in the first embodiment, the same reference numerals are used and the repeated descriptions are appropriately omitted. Figure 2 the same

[0057] In Figure 7 the fifth embodiment, a pressure discharging path is formed by making the inner diameter of the through hole 22a' that conducts the back pressure chamber 2R and the inside of the housing 14 in the guiding portion 22 on the upper side of the guiding member 2 larger than that in the first embodiment. The flow path cross-sectional area of the through hole 22a' is larger than the cross-sectional area of the gap of the needle valve portion.

[0058] In Figure 8 the sixth embodiment, a plurality of (two in the figure) through holes 22a'' that conduct the back pressure chamber 2R and the inside of the housing 14 are provided in the guiding portion 22 on the upper side of the guiding member 2 to form a pressure discharging path. The total flow path cross-sectional area of the plurality of through holes 22a'' is larger than the cross-sectional area of the gap of the needle valve portion.

[0059] In this fifth and sixth embodiments, the high-pressure fluid also flows into the back pressure chamber 2R through the gap between the guiding projection 43 of the needle valve 4 and the washer 42 via the needle valve guiding hole 32a. However, the fluid in the back pressure chamber 2R is discharged from the housing 14 to the main valve chamber 1R through the through hole 25a of the flange 25 via the guiding path 22a' or 22a'' as the pressure discharging path. Therefore, similar to the first embodiment, the back pressure chamber 2R does not become high-pressure, and the main valve element 3 rises due to the high-pressure fluid from the main valve port 13a side, compresses the main valve spring 35 and holds it at a predetermined position. Thus, the fully open position of the main valve element 3 is stabilized at a predetermined position, and therefore the flow rate (fully open flow rate) of the fluid flowing from the second joint pipe 12 to the first joint pipe 11 is stable. In addition, since the vibration of the main valve element 3 is prevented, noise can be prevented.

[0060] Hereinafter, based on Figure 9 the refrigeration cycle system of the present invention will be described. The refrigeration cycle system is used, for example, in air conditioners such as household air conditioners. The electric valve 100 of each of the above embodiments is provided between the first indoor heat exchanger 91 (which operates as a cooler during dehumidification) and the second indoor heat exchanger 92 (which operates as a heater during dehumidification) of the air conditioner, and together with the compressor 95, the four-way valve 96, the outdoor heat exchanger 94, and the electronic expansion valve 93, constitutes a heat pump refrigeration cycle. The first indoor heat exchanger 91, the second indoor heat exchanger 92, and the electric valve 100 are arranged indoors, and the compressor 95, the four-way valve 96, the outdoor heat exchanger 94, and the electronic expansion valve 93 are arranged outdoors and constitute a refrigeration and heating device.

[0061] The electric valve 100 as an embodiment of the dehumidifying valve keeps the main valve core fully open during refrigeration or heating other than during dehumidification, and the first indoor heat exchanger 91 and the second indoor heat exchanger 92 are one indoor heat exchanger. And, this integrated indoor heat exchanger and the outdoor heat exchanger 94 function alternatively as an "evaporator" and a "condenser". That is, the electric valve 93 as the electronic expansion valve is provided between the evaporator and the condenser.

[0062] The above refrigeration cycle system is an example of using the electric valve of the present invention as the dehumidifying valve, but the electric valve of the present invention can also be applied to the electric valve 93 as the above-mentioned electronic expansion valve. In this case, it can be either with or without a dehumidifying valve.

[0063] In addition, the present invention is not limited to the above embodiments, and includes other structures and the like that can achieve the object of the present invention, and deformations and the like as shown below are also included in the present invention. For example, in the above embodiments, the electric valve 100 for an air conditioner such as a household air conditioner is illustrated, but the electric valve of the present invention is not limited to household air conditioners, and can also be a commercial air conditioner, and is not limited to air conditioners, and can also be applied to various refrigerators and the like.

[0064] Above, the embodiments of the present invention have been described in detail with reference to the drawings. Although other embodiments have also been described in detail, the specific structure is not limited to these embodiments, and design changes and the like within the scope not departing from the gist of the present invention are also included in the present invention.

Claims

1. An electric valve, comprising: a valve housing that houses a main valve chamber therein; and an outer housing that engages with the upper portion of the valve housing and houses a magnetic rotor therein. On a side surface of the valve housing, there is provided a first joint pipe for fluid inlet / outlet that opens to the main valve chamber, and a second joint pipe for fluid inlet / outlet that is connected to a main valve port provided at the lower portion of the valve housing. The electric valve includes: a main valve element that opens and closes the main valve port of the main valve chamber; a sub-valve element that changes the opening degree of a sub-valve port of a sub-valve chamber provided in the main valve element; a main valve spring that biases the main valve element toward the main valve port side; a driving portion that drives the sub-valve element to advance and retreat in the axial direction; and a guiding member that inserts the main valve element into a main valve guiding hole and guides the main valve element in the axial direction. The sub-valve element is slidably inserted into a sub-valve guiding hole of the main valve element in the axial direction. It has a two-stage flow control region including a small flow control region and a large flow control region. Wherein, The small flow control region is: when the main valve element closes the main valve port, the sub-valve element changes the opening degree of the sub-valve port; the large flow control region is: the main valve element makes the main valve port in a fully open state, and allows a large flow of fluid flowing in from the main valve port to flow from the main valve chamber to a side port. The electric valve is characterized in that it is provided with a pressure relief path that conducts a back pressure chamber and the main valve chamber from the state where the main valve element closes the main valve port until the fully open state. The inner diameter of the main valve port is larger than the inner diameter of the main valve guiding hole.

2. The electric valve according to claim 1, characterized in that the pressure relief path is formed between a D-shaped cut surface on a side portion of the main valve element and an inner peripheral surface of the main valve guiding hole.

3. The electric valve according to claim 1, characterized in that the pressure relief path is formed by a groove parallel to the axis on the inner periphery of the main valve guiding hole.

4. The electric valve according to claim 1, characterized in that the pressure relief path is formed by a groove parallel to the axis on the outer periphery of the main valve element.

5. The electric valve according to claim 1, characterized in that the pressure relief path is formed by a gap between a side portion of the main valve element and an inner peripheral surface of the main valve guiding hole.

6. The electric valve according to claim 1, characterized in that the pressure relief path is formed by a through hole that conducts the upper portion of the main valve guiding hole and the inside of the outer housing.

7. A refrigeration cycle system, including a compressor, an indoor heat exchanger, an outdoor heat exchanger, an electronic expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger, and a dehumidifying valve provided in the indoor heat exchanger. The refrigeration cycle system is characterized in that the electric valve described in any one of claims 1 to 6 is used as the dehumidifying valve.

8. A refrigeration cycle system, including a compressor, an indoor heat exchanger, an outdoor heat exchanger, and an electronic expansion valve provided between the indoor heat exchanger and the outdoor heat exchanger. The refrigeration cycle system is characterized in that the electric valve described in any one of claims 1 to 6 is used as the electronic expansion valve.

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