Electrically operated valve and refrigeration cycle system

Abstract

Provided is an electric valve and a refrigeration cycle system. In an electric valve in which a needle valve (4) controls a small flow rate, the maximum flow rate in the small flow rate control region is suppressed from deviating, and the controllable range in the small flow rate control region is made large. The needle valve (4) having a second conical frustum portion (44) in which the diameter gradually decreases toward the front end is disposed on the axis L of the sub valve port (33a). The needle valve (4) is moved in and out on the axis by a driving portion (5). The small flow rate control region is obtained by the needle valve (4) and the sub valve port (33a). The large flow rate control region is obtained by the main valve core (3) and the main valve port (13a). A second straight portion (45) having a constant diameter is provided in connection with the smallest diameter portion of the second conical frustum portion (44) of the needle valve (4). The second straight portion (45) is kept inside the sub valve port (33a) at the position where the second conical frustum portion (44) is withdrawn from the sub valve port (33a).

Description

[0001] This invention is a divisional application of the invention application with application number 201910749370.8, entitled "Electric Valve and Refrigeration Circulation System", filed on August 14, 2019. Technical Field

[0002] This invention relates to electric valves used in refrigeration circulation systems and the like, as well as refrigeration circulation systems. Background Technology

[0003] Currently, electric valves installed in the refrigeration cycle of air conditioners include, for example, the electric valve disclosed in Japanese Patent No. 2898906 (Patent Document 1). This electric valve includes: a main valve core (second valve core) that changes the opening degree of the main valve port (large diameter valve port) of the valve chamber; a secondary valve core (first valve core) that changes the opening degree of the secondary valve port (small diameter valve port) formed in the main valve core; and a drive unit for driving the secondary valve core by an electric motor (stepper motor).

[0004] Figure 12 This is a line graph showing the relationship (flow characteristic) between the drive pulse of the electric motor in the electric valve (the lift of the secondary valve core) and the flow rate of the refrigerant flowing through the electric valve. Furthermore, in this electric valve, when the main valve core is seated and the main valve port is closed, the secondary valve core, driven by the electric motor, changes the opening degree of the secondary valve port. At this time, the opening degree of the secondary valve port is controlled according to the drive pulse of the electric motor, such as... Figure 12 The flow characteristics are obtained in the small flow control region as shown. Furthermore, the secondary valve core is lifted by the electric motor, thereby engaging with the main valve core. The main valve core and secondary valve core are lifted together, opening the main valve port. The opening degree of the main valve port is changed by the main valve core, such as... Figure 12 The flow characteristics are obtained in the manner shown, thus achieving a large flow control region. Therefore, the electric valve has two levels of flow control regions: a small flow control region and a large flow control region.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 2898906 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In existing electric valves, in multiple electric valves, for example in those that become Figure 13 In an electric valve manufactured using the method of representing the flow characteristics of the target as shown by the solid line, the flow characteristics will also deviate due to variations in component dimensions, etc. The range of this deviation depends on the influence of component dimensional tolerances, assembly tolerances, etc., but for example, in... Figure 13In the example, the flow characteristic relative to the center shown by the solid line is represented by the upper limit shown by the dotted line and the lower limit shown by the dashed line. Furthermore, in the flow characteristic, there is an inflection point at the boundary between the small flow control region and the large flow control region, and a deviation occurs at the position of this inflection point. Therefore, in order to perform pulse control of the electric valve, within the deviation range, the drive pulse with the minimum upper limit compared to the small flow control region needs to be used. Figure 13 The drive pulse at point A is smaller than the upper limit, and the range up to the upper limit is taken as the actual controllable range of micro-flow for micro-flow control.

[0010] In addition, Figure 13 The flow rate at point A also deviates, for example, at the upper limit of the flow characteristic (the flow characteristic of the dotted line). If the valve opening is too large, there is a possibility that the flow rate cannot be completely reduced. Therefore, it is necessary to make the upper limit of the range for controlling small flow rates lower than point A, and to use this range as the range for controlling small flow rates. Thus, in existing electric valves, it is necessary to reduce the range that can be controlled with small flow rates. This is not limited to two-stage control based on the main valve core and the auxiliary valve core; it also becomes a problem in electric valves where the flow rate is controlled by the truncated cone of the needle valve. For example, if the deviation of the maximum flow rate in the small flow rate control region becomes large, there is a possibility that the flow rate cannot be completely reduced. It is necessary to consider the flow rate deviation to reduce the range of drive pulses used for small flow rate control in the small flow rate control region, that is, the range of controllable micro-flow rates.

[0011] The objective of this invention is to suppress the deviation of the maximum flow rate in the small flow rate control region in an electric valve controlled by a needle valve, and to make the controllable range of the small flow rate actually used for micro flow rate control a large range.

[0012] Solution for solving the problem

[0013] The electric valve of Scheme 1 has a needle valve with a truncated cone-shaped portion whose diameter gradually decreases towards the front end of the small-diameter valve port. The needle valve is disposed on the axis of the small-diameter valve port. The rotational motion of the rotor of the electric motor is converted into linear motion by a threaded feed mechanism, so that the needle valve moves forward and backward along the axis. The refrigerant flow rate is controlled according to the opening area of ​​the gap between the opening of the small-diameter valve port and at least the truncated cone portion of the needle valve. The electric valve is characterized in that the needle valve is configured to have a straight portion with a constant diameter connected to the minimum diameter portion of the truncated cone portion. When the minimum diameter portion of the truncated cone portion is disengaged from the small-diameter valve port in the axis direction, the straight portion remains inside the small-diameter valve port.

[0014] The electric valve of Scheme 2, according to the electric valve of Scheme 1, is characterized by having a main valve core that changes the opening degree of the main valve port of the valve chamber, and having a small-diameter valve port formed on the main valve core. It has two flow control regions: a small flow control region where the needle valve changes the opening degree of the small-diameter valve port, and a large flow control region where the main valve core changes the opening degree of the main valve port. The needle valve is configured to engage with the main valve core at a position where the minimum diameter portion of the truncated cone portion disengages from the small-diameter valve port. The main valve core moves integrally with the needle valve in the engaged state to change the opening degree of the main valve port.

[0015] The refrigeration cycle system of Scheme 3 includes a compressor, a condenser, an evaporator, and an electronic expansion valve disposed between the condenser and the evaporator, characterized in that the electric valve described in Scheme 1 is used as the electronic expansion valve.

[0016] The refrigeration cycle system of Scheme 4 includes a compressor, an indoor heat exchanger, an outdoor heat exchanger, an electronic expansion valve disposed between the indoor heat exchanger and the outdoor heat exchanger, and a dehumidification valve disposed in the indoor heat exchanger. The characteristic feature is that the electric valve described in Scheme 2 is used as the dehumidification valve.

[0017] The effects of the invention are as follows.

[0018] According to the electric valve of scheme 1 or 2, the refrigerant flow rate in the small flow control region is controlled based on the opening area of ​​the gap between the opening of the small-diameter valve port and the truncated cone portion of the needle valve. The needle valve has a straight section with a constant diameter connected to the minimum diameter portion of the truncated cone portion. At the position where the minimum diameter portion of the truncated cone portion disengages from the small-diameter valve port, the straight section remains within the small-diameter valve port, thereby transitioning the small flow control region to a constant flow region. Therefore, deviations from the maximum flow rate within the small flow control region can be suppressed, preventing the inability to reduce the maximum flow rate. Furthermore, the range of the drive pulses actually used for controlling the minute flow rate—that is, the controllable range of the minute flow rate—can be expanded, thereby improving the controllability of the minute flow rate controllable range.

[0019] The same effect as that of Scheme 1 or 2 can be obtained by using the refrigeration cycle system of Scheme 3 or 4. Attached Figure Description

[0020] Figure 1 This is a longitudinal sectional view of the electric valve according to the first embodiment of the present invention.

[0021] Figure 2 This is an enlarged cross-sectional view of the main part of the electric valve in the first embodiment when the needle valve is located closest to the auxiliary valve port.

[0022] Figure 3This is an enlarged cross-sectional view of the main part of the electric valve in the first embodiment when the needle valve is located between the position closest to the auxiliary valve port and the position engaged with the main valve core.

[0023] Figure 4 This is an enlarged cross-sectional view of the main part of the electric valve in the first embodiment when the needle valve is engaged with the main valve core.

[0024] Figure 5 This is an enlarged cross-sectional view of the main part of the electric valve in the first embodiment, showing the fully open state of the main valve core.

[0025] Figure 6 This is a line graph showing the relationship between the pulse quantity of the drive pulse and the flow rate in the electric valve of the first embodiment.

[0026] Figure 7 This is a longitudinal sectional view of the electric valve according to the second embodiment of the present invention.

[0027] Figure 8 This is an enlarged cross-sectional view showing the main part of the needle valve in the second embodiment, corresponding to the lowest position of the magnetic rotor.

[0028] Figure 9 This is a main enlarged cross-sectional view showing the state of refrigerant flowing through the gap between the second truncated cone portion and the valve port of the needle valve in the second embodiment.

[0029] Figure 10 This is an enlarged cross-sectional view of the main part showing the state in which the second straight section of the needle valve in the second embodiment is located inside the valve port.

[0030] Figure 11 This is a diagram illustrating the refrigeration cycle system of an embodiment.

[0031] Figure 12 It is a line graph showing the relationship between the pulse quantity of the drive pulse and the flow rate in an existing electric valve.

[0032] Figure 13 This is a diagram illustrating the existing problem points.

[0033] In the picture:

[0034] 1—Valve housing, 1R—Valve chamber, 11—First connector pipe, 12—Second connector pipe, 13—Main valve seat, 13a—Main valve port, L—Axis, 2—Guide component, 21—Press-in part, 22—Guide part, 22a—Guide hole, 23—Bracket part, 23a—Internal thread part, 24—Flange part, 3—Main valve core, 3a—Main valve spring, 31—Main valve part, 32—Retaining part, 33—Secondary valve seat, 33a—Secondary valve port (small diameter valve port), 4—Needle valve, 41—Valve shaft, 4 2—First truncated cone section, 43—First straight section, 44—Second truncated cone section, 45—Second straight section, 46—Washer, 47—Guide protrusion, 5—Drive section, 5A—Stepper motor (electric motor), 51—Rotor shaft, 51a—External thread section, 52—Magnetic rotor, 52a—Protrusion, 53—Stator coil, 5B—Threaded feed mechanism, 5C—Limiting mechanism, 10—Valve housing, 10R—Valve chamber, 110—First connection Head tube, 120—Second connector tube, 130—Valve seat assembly, 130a—Valve port (small diameter port), 20—Guide assembly, 210—Press-in part, 220—Guide part, 220a—Guide hole, 230—Bracket part, 230a—Internal thread part, 240—Flange part, 30—Valve bracket part, 40—Needle valve, 410—Protrusion, 420—First truncated cone part, 430—First straight part, 440—Second truncated cone part (truncated cone part), 450—Second straight part 50—Drive section, 50A—Stepper motor (electric motor), 510—Rotor shaft, 510a—External thread section, 520—Magnetic rotor, 530—Stator coil, 511—Protrusion, 512—Flange section, 50B—Threaded feed mechanism, 50C—Limiting mechanism, 91—First indoor heat exchanger, 92—Second indoor heat exchanger, 93—Outdoor heat exchanger, 94—Compressor, 95—Four-way valve, 100—Electric valve, 200—Electric valve. Detailed Implementation

[0035] Next, embodiments of the electric valve and refrigeration circulation system of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a longitudinal sectional view of the electric valve according to the first embodiment. Figure 2 This is an enlarged cross-sectional view of the main part of the electric valve in the first embodiment when the needle valve is located closest to the auxiliary valve port. Figure 3 This is an enlarged cross-sectional view of the main part of the needle valve in the electric valve of the first embodiment, when it is located between the position closest to the auxiliary valve port and the position engaged with the main valve core. Figure 4 This is an enlarged cross-sectional view of the main part of the needle valve in the electric valve of the first embodiment when it is engaged with the main valve core. Figure 5 This is an enlarged cross-sectional view showing the main portion of the electric valve core in the fully open state of the first embodiment. Furthermore, the concept of "upper and lower" in the following description is different from... Figures 1 to 4The upper and lower parts correspond to each other in the attached diagram. The electric valve 100 includes a valve housing 1, a guide component 2, a main valve core 3, a needle valve 4, and a drive unit 5.

[0036] The valve body 1 is made of materials such as brass or stainless steel and is generally cylindrical, with a valve chamber 1R inside. A first connector pipe 11, communicating with the valve chamber 1R, is connected to one side of the outer periphery of the valve body 1, and a second connector pipe 12 is connected to a cylindrical portion extending downward from the lower end. A cylindrical main valve seat 13 is formed on the valve chamber 1R side of the second connector pipe 12, and the inner side of the main valve seat 13 becomes a main valve port 13a. The second connector pipe 12 communicates with the valve chamber 1R via the main valve port 13a. The main valve port 13a is a cylindrical through-hole centered on the axis L. Furthermore, the first connector pipe 11 and the second connector pipe 12 are fixed to the valve body 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-in portion 21 pressed into the inner circumferential surface of the valve housing 1, a generally cylindrical guide portion 22 located inside the press-in portion 21, a support portion 23 extending from the upper part of the guide portion 22, and an annular flange portion 24 located on the outer periphery of the guide portion 22. The press-in portion 21, the guide portion 22, and the support portion 23 are configured as a single resin component. Furthermore, the flange portion 24 is, for example, a metal plate such as brass or stainless steel, and is integrally formed with the resin press-in portion 21 and the support portion 22 by inlay molding.

[0038] Furthermore, the guide member 2 is assembled to the valve housing 1 and fixed to the upper end of the valve housing 1 via the flange portion 24 and welding. In the guide member 2, a cylindrical guide hole 22a coaxial with the axis L is formed in the guide portion 22, and an internal thread portion 23a coaxial with the guide hole 22a and its threaded hole are formed at the center of the support portion 23. The main valve core 3 is disposed within the guide hole 22a of the support portion 23.

[0039] The main valve core 3 has a main valve portion 31 that sits and leaves the main valve seat 13, a retaining portion 32 with a cylindrical needle-shaped guide hole 32a, and a secondary valve seat 33. A washer 46 and a guide protrusion 47, which are mounted on the valve shaft 41 described below, are inserted into the needle-shaped guide hole 32a of the retaining portion 32. An annular retainer 321 is fitted and fixed to the upper end of the retaining portion 32, either by fitting or by welding. The upper outer periphery of the retaining portion 32 is tapered, and a main valve spring 3a is disposed between the upper outer periphery of the retaining portion 32 and the upper end of the guide hole 22a. The main valve spring 3a applies force to the main valve core 3 in the direction of the main valve seat 13 (closing direction). The secondary valve seat 33 is located at the lower end of the needle-shaped guide hole 32a, and a secondary valve port 33a, serving as a "small-diameter valve port," is formed at its center. This secondary valve port 33a is circular in shape with the axis L as its center. Furthermore, at least one location on the side of the retaining part 32 is provided with a through hole 32b that allows the needle-shaped guide hole 32a to communicate with the valve chamber 1R. As explained below, when the needle valve 4 opens the secondary valve port 33a, the valve chamber 1R, the needle-shaped guide hole 32a, the secondary valve port 33a, and the main valve port 13a are connected.

[0040] The needle valve 4 integrally comprises: a valve shaft 41 integrally formed with the rotor shaft 51 at the lower end of the rotor shaft 51 and connected to the rotor shaft 51 side; a first truncated cone portion 42 connected to the valve shaft 41 side; a first straight portion 43 connected to the first truncated cone portion 42; a second truncated cone portion 44 connected to the first straight portion 43; and a second straight portion 45 connected to the second truncated cone portion 44. Furthermore, the needle valve 4 has an annular washer 46 disposed on the valve shaft 41 and a guide protrusion 47 fixed to the valve shaft 41. The guide protrusion 47 is fixed independently to the valve shaft 41, but the guide protrusion 47 may also be integrally formed with the valve shaft 41. In addition, the terms "truncated cone portion" and "straight portion" in this invention correspond to the second truncated cone portion 44 and the second straight portion 45, respectively. The first straight portion 43 is formed with a diameter that matches and can be inserted into the secondary valve port 33a, and its side surface has the same diameter in the direction of the axis L. Furthermore, the apex angle of the second frustum-shaped portion 44 (the angle formed by generatrices that are 180° apart in the direction about the axis L) is smaller than the apex angle of the first frustum-shaped portion 42. Also, the diameter of the side surface of the second straight portion 45 is smaller than the diameter of the secondary valve port 33a, and they have the same diameter in the direction of the axis L. Moreover, the washer 46 and the guide protrusion 47 can be slidably inserted into the needle-shaped guide hole 32a.

[0041] At the upper end of the valve housing 1, a housing 14 is airtightly fixed by welding or the like, and a drive unit 5 is formed inside and outside the housing 14. The drive unit 5 includes a stepper motor 5A as an "electric motor", a threaded feed mechanism 5B that uses the rotation of the stepper motor 5A to move the needle valve 4 forward and backward, and a limiting mechanism 5C that restricts the rotation of the stepper motor 5A.

[0042] The stepper motor 5A comprises a rotor shaft 51, a magnetic rotor 52 rotatably disposed inside a housing 14, a stator coil 53 disposed opposite the magnetic rotor 52 on the outer periphery of the housing 14, and other components not shown, such as a yoke and external fittings. The rotor shaft 51 is mounted at the center of the magnetic rotor 52 via a bushing, and an external thread 51a is formed on the outer periphery of the rotor shaft 51 on the side near the guide member 2. This external thread 51a is threadedly engaged with the internal thread 23a of the guide member 2, thereby the guide member 2 supports the rotor shaft 51 on the axis L. Furthermore, the internal thread 23a of the guide member 2 and the external thread 51a of the rotor shaft 51 constitute a threaded feed mechanism 5B.

[0043] Based on the above structure, driven by the stepper motor 5A, the magnetic rotor 52 and rotor shaft 51 rotate. The threaded feed mechanism 5B, composed of the external thread 51a of the rotor shaft 51 and the internal thread 23a of the guide member 2, moves the rotor shaft 51 along the axis L. Furthermore, the needle valve 4 moves forward and backward along the axis L, thereby approaching or separating from the auxiliary valve port 33a. This controls the opening degree of the auxiliary valve port 33a. Additionally, the needle valve 4 (washer 46) engages with the main valve core 3 (retainer 321), and the main valve core 3 moves together with the needle valve 4, sitting and leaving the main valve seat 13. This controls the flow rate of refrigerant flowing from the first connector pipe 11 to the second connector pipe 12, or from the second connector pipe 12 to the first connector pipe 11. A protrusion 52a is formed in the magnetic rotor 52. As the magnetic rotor 52 rotates, the protrusion 52a causes the rotation limiting mechanism 5C to work, limiting the lowermost and uppermost positions of the rotor shaft 51 (and the magnetic rotor 52). Figure 1 and Figure 2 This shows the rotor shaft 51 (and magnetic rotor 52) in the lowest position.

[0044] Figure 6 This is a line graph showing the relationship between the pulse quantity (= valve opening) of the drive pulse in stepper motor 5A and the flow rate. (Refer to...) Figures 2 to 6 The detailed operation of the electric valve 100 is explained.

[0045] The electric valve 100 operates as follows. First, in Figure 2 (and Figure 1In the current state, the main valve portion 31 of the main valve core 3 sits on the main valve seat 13, thus closing the main valve port 13a. On the other hand, the first straight portion 43 of the needle valve 4, located closest to the secondary valve port 33a, is inserted into the secondary valve port 33a, but the needle valve 4 is not seated on the secondary valve seat 33, and refrigerant flows slightly through the gap between the outer circumferential surface of the first straight portion 43 and the secondary valve port 33a. That is, as... Figure 6 As shown, even when the drive pulse is at the reference point (zero point), a small flow rate is generated.

[0046] Next, the stepper motor 5A is used to drive the magnetic rotor 52 to rotate, thereby raising the needle valve 4, as... Figure 3 As shown, the first straight portion 43 of the needle valve 4 disengages from the secondary valve port 33a, and a flow path is formed by the gap between the second truncated cone portion 44 of the needle valve 4 and the secondary valve port 33a. Here, the diameter of the second truncated cone portion 44 gradually decreases, thereby increasing the gap between it and the secondary valve port 33a, expanding the flow path, and thus... Figure 6 As shown, the flow rate gradually increases. At this time, since the main valve portion 31 of the main valve core 3 remains seated on the main valve seat 13, the increase in flow rate is minimal until the second conical portion 44 of the needle valve 4 disengages from the auxiliary valve port 33a. Thus, by moving the needle valve 4 from its position closest to the auxiliary valve port 33a to the position where the second conical portion 44 disengages from the auxiliary valve port 33a, the opening degree of the auxiliary valve port 33a is changed. This control region is a small flow rate control region. Compared to the large flow rate control region, the change in flow rate relative to the pulse amount (= valve lift) of the stepper motor 5A within this small flow rate control region is smaller.

[0047] Next, as Figure 4 As shown, if needle valve 4 is raised to the position where it engages with main valve core 31 and gasket 46 engages with main valve core 3, then main valve core 3 and needle valve 4 rise together. Furthermore, if it rises further, then... Figure 5 As shown, the main valve core 3 is lifted by the valve shaft 41 (and the washer 46), thereby opening the valve by separating the main valve section 31 from the main valve seat 13. Thus, the control region that causes the main valve core 3 to rise from the seated position (closed position) towards the open position (open position) is a high-flow control region, where the flow rate varies significantly relative to the pulse amount (= valve lift) of the stepper motor 5A. Furthermore, when the main valve core 3 is raised to... Figure 5 In the fully open state shown in the valve position, the flow rate becomes the maximum. Furthermore, as the flow rate in the fully open state, the opening area of ​​the gap between the main valve section 31 and the main valve seat 13 is equal to or larger than the opening area of ​​the primary connector pipe 11 and the secondary connector pipe 12. This is set to a state where the flow rate is not reduced by the main valve section 31 and the main valve port 13a, that is, the opening degree at which the electric valve 100 functions as a simple flow path.

[0048] Here, from Figure 3 The position shown until Figure 4 Up to the position shown, there exists a moment when the boundary portion (the smallest diameter portion of the truncated cone) between the second conical portion 44 and the second straight portion 45 of the needle valve 4 disengages from the auxiliary valve port 33a. From that moment until Figure 4 Up to the position shown, only the second straight portion 45 is located within the secondary valve port 33a, thus the opening area of ​​the gap between the secondary valve port 33a and the second straight portion 45 remains constant. Therefore, as Figure 6 As shown, a constant flow range is generated from the end of the small flow control region to the large flow control region, maintaining a constant flow rate. Therefore, according to this electric valve 100, deviations in the maximum flow rate within the small flow control region can be suppressed, thereby sufficiently reducing the maximum flow rate at the secondary valve port 33a. Furthermore, the range of the drive pulses actually used for controlling the minute flow rate, i.e., the controllable range of the minute flow rate, can be expanded, thereby improving the controllability of the minute flow rate controllable range.

[0049] Figure 7 This is a longitudinal sectional view of the electric valve according to the second embodiment. Figure 8 This is an enlarged cross-sectional view showing the main part of the needle valve corresponding to the lowest position of the magnetic rotor in the second embodiment. Figure 9 This is a magnified cross-sectional view showing the state of refrigerant flow in the gap between the second truncated cone portion and the valve port of the needle valve in the second embodiment. Figure 10 This is an enlarged cross-sectional view showing the main portion of the needle valve in the second embodiment located within the valve orifice. Furthermore, the concept of "upper and lower" in the following description is different from... Figure 7 The top and bottom correspondences in the attached diagram.

[0050] The electric valve 200 includes a valve housing 10, a guide component 20, a valve frame 30, a needle valve 40, and a drive unit 50.

[0051] The valve body 10 is formed into a generally cylindrical shape, for example, from brass or stainless steel, and has a valve chamber 10R inside. A first connector pipe 110, which communicates with the valve chamber 10R, is connected to one side of the outer periphery of the valve body 10, and a second connector pipe 120 is connected to a cylindrical portion extending downward from the lower end. A valve seat component 130 is fitted into the valve chamber 10R side of the second connector pipe 120. The inner side of the valve seat component 130 forms a valve port 130a, which serves as a "small-diameter valve port," through which the second connector pipe 120 communicates with the valve chamber 10R. The valve port 130a is a cylindrical through-hole centered on the axis L. Furthermore, the first connector pipe 110 and the second connector pipe 120 are fixed to the valve body 10 by brazing or the like.

[0052] A guide member 20 is installed at the opening at the upper end of the valve housing 10. The guide member 20 has a press-in portion 210 pressed into the inner circumferential surface of the valve housing 10, a generally cylindrical guide portion 220 located inside the press-in portion 210, a support portion 230 extending from the upper part of the guide portion 220, and an annular flange portion 240 located on the outer periphery of the guide portion 220. The press-in portion 210, the guide portion 220, and the support portion 230 are configured as a single resin component. Furthermore, the flange portion 240 is, for example, a metal plate such as brass or stainless steel, and is integrally formed with the resin press-in portion 210 and the support portion 220 by inlay molding.

[0053] Furthermore, the guide member 20 is assembled to the valve housing 10 and fixed to the upper end of the valve housing 10 via the flange portion 240 and welding. In the guide member 20, a cylindrical guide hole 220a coaxial with the axis L is formed in the guide portion 220, and an internal thread portion 230a coaxial with the guide hole 220a and its threaded hole are formed at the center of the support portion 230. Moreover, a valve bracket portion 30 and a needle valve 40 are provided within the guide member 20 and the valve chamber 10R.

[0054] The valve holder 30 includes an annular thrust washer 310, a cylindrical guide tube 320, a spring seat 330, and a helical spring 340. The guide tube 320 has an annular top 320a by bending its upper end inward. On the other hand, the rotor shaft 510 has a protrusion 511 at its lower end than the external threaded portion 510a, and a flange portion 512 is integrally formed on the protrusion 511. The protrusion 511 is embedded in the top 320a and the thrust washer 310 is mounted thereon. Furthermore, the spring seat 330 is provided in the guide tube 320 and is movable along the axis L. With the spring seat 330 and the helical spring 340 housed, a needle valve 40 is fixed at the lower end of the guide tube 320.

[0055] The needle valve 40 integrally comprises: a protrusion 410 fixed to the guide tube 320; a first frustum-cone portion 420 formed at the lower part of the protrusion 410; a first straight portion 430 connected to the first frustum-cone portion 420; a second frustum-cone portion 440 connected to the first straight portion 430; and a second straight portion 450 connected to the second frustum-cone portion 440. Furthermore, in this invention, "frustum-cone portion" and "straight portion" correspond to the second frustum-cone portion 440 and the second straight portion 450, respectively. The first straight portion 430 is formed with a diameter that matches and can be inserted into the valve port 130a, and its side surfaces have the same diameter in the direction of the axis L. Moreover, the apex angle of the second frustum-cone portion 440 (the angle formed by generatrices that are 180° apart in the direction about the axis L) is smaller than the apex angle of the first frustum-cone portion 420. Furthermore, the diameter of the side of the second straight section 450 is smaller than the diameter of the valve port 130a, and they are the same diameter in the direction of the axis L.

[0056] At the upper end of the valve housing 10, a housing 140 is airtightly fixed by welding or the like, and a drive unit 50 is formed inside and outside the housing 140. The drive unit 50 includes a stepper motor 50A as an "electric motor", a threaded feed mechanism 50B that uses the rotation of the stepper motor 50A to move the needle valve 40 forward and backward, and a limiting mechanism 50C that limits the rotation of the stepper motor 50A.

[0057] The stepper motor 50A comprises a rotor shaft 510, a magnetic rotor 520 rotatably disposed inside a housing 140, a stator coil 530 disposed opposite the magnetic rotor 520 on the outer periphery of the housing 140, and other components not shown, such as a yoke and external fittings. The rotor shaft 510 is mounted at the center of the magnetic rotor 520 via a bushing, and an external thread 510a is formed on the outer periphery of the rotor shaft 510 on the side near the guide member 20. This external thread 510a is threadedly engaged with the internal thread 230a of the guide member 20, thereby supporting the rotor shaft 510 on the axis L. Furthermore, the internal thread 230a of the guide member 20 and the external thread 510a of the rotor shaft 510 constitute a threaded feed mechanism 50B.

[0058] Based on the above structure, driven by the stepper motor 50A, the magnetic rotor 520 and rotor shaft 510 rotate. The threaded feed mechanism 50B, composed of the external threaded portion 510a of the rotor shaft 510 and the internal threaded portion 230a of the guide member 20, moves the rotor shaft 510 along the axis L. Furthermore, the needle valve 40 moves forward and backward along the axis L, thereby bringing the needle valve 40 closer to or further away from the valve port 130a. This controls the opening degree of the valve port 130a, controlling the flow rate of refrigerant flowing from the first connector pipe 110 to the second connector pipe 120, or from the second connector pipe 120 to the first connector pipe 110. A protrusion 520a is formed on the magnetic rotor 520. With the rotation of the magnetic rotor 520, the protrusion 520a activates the rotation limiting mechanism 50C, limiting the lowermost and uppermost positions of the rotor shaft 510 (and the magnetic rotor 520). Figure 7 and Figure 8 This shows the rotor shaft 510 (and magnetic rotor 520) in its lowest position.

[0059] The electric valve 200 operates as follows. First, in... Figure 7 and Figure 8 In this state, the first straight portion 430 of the needle valve 40, located closest to the valve port 130a, is inserted into the valve port 130a, and refrigerant flows slightly through the gap between the outer peripheral surface of the first straight portion 430 and the valve port 130a.

[0060] Next, the magnetic rotor 520 is rotated by the stepper motor 50A to raise the needle valve 40, thereby... Figure 9 As shown, the first straight portion 430 of the needle valve 40 disengages from the valve port 130a, and a flow path is formed by the gap between the second truncated cone portion 440 of the needle valve 40 and the valve port 130a. Here, the diameter of the second truncated cone portion 440 gradually decreases, thereby increasing the gap between it and the valve port 130a, expanding the flow path, and further... Figure 6 Similarly, the flow rate gradually increases, but in this state, the increase in flow rate is small. Thus, the control region that changes the opening degree based on the gap between the second conical portion 440 of the needle valve 40 and the valve port 130a is a small flow control region. Compared with the large flow control region, the change in flow rate in this small flow control region relative to the pulse amount (= valve lift amount) of the drive pulse of the stepper motor 50A is smaller.

[0061] Here, from Figure 9 The position shown until Figure 10Up to the position shown, there exists a moment when the boundary portion (the smallest diameter of the truncated cone portion) between the second conical portion 440 and the second straight portion 450 of the needle valve 40 disengages from the valve port 130a. From this moment on, only the second straight portion 450 is located within the valve port 130a, thus the opening area of ​​the gap between the valve port 130a and the second straight portion 450 remains constant. Furthermore, if the second straight portion 450 disengages from the valve port 130a, a large flow control region is formed where the flow rate increases sharply towards the fully open state. Thus, a constant flow region that maintains a constant flow rate is generated from the end of the small flow control region to the large flow control region. Therefore, according to this electric valve 200, deviations of the maximum flow rate within the small flow control region can be suppressed, thereby sufficiently reducing the maximum flow rate at the valve port 130a. Moreover, the range of the drive pulse actually used for controlling the small flow rate, i.e., the controllable range of the small flow rate, can be made large, thereby improving the controllability of the small flow rate controllable range.

[0062] Next, based on Figure 11 The refrigeration cycle system of the present invention will be described. This refrigeration cycle system is used, for example, in air conditioners such as household air conditioners. The electric valve 100 of the first embodiment described above is provided as a "dehumidification control valve" 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). Furthermore, the electric valve 200 of the second embodiment described above is provided as an "electronic expansion valve" between the second indoor heat exchanger 92 and the outdoor heat exchanger 93. Moreover, the electric valve 100, electric valve 200, outdoor heat exchanger 93, compressor 94, and four-way valve 95 constitute a heat pump type refrigeration cycle. The first indoor heat exchanger 91, second indoor heat exchanger 92, and electric valve 100 are located indoors, while the outdoor heat exchanger 93, compressor 94, four-way valve 95, and electric valve 200 are located outdoors, thereby constituting a cooling and heating device.

[0063] In the electric valve 100, which is the first embodiment of the dehumidification valve, during cooling or heating (other than dehumidification), the main valve core is fully open, and the first indoor heat exchanger 91 and the second indoor heat exchanger 92 become a single indoor heat exchanger. Furthermore, this integrated indoor heat exchanger and outdoor heat exchanger 93 can selectively function as either an "evaporator" or a "condenser." That is, the electric valve 200, which functions as an electronic expansion valve, is located between the evaporator and the condenser.

[0064] In the above embodiments, internal thread portions 23a and 230a are formed in the guide members 2 and 20, and external thread portions 51a and 510a are formed in the rotor shafts 51 and 510, thereby constituting a threaded feed mechanism. However, it is not limited to this combination of threaded parts. Alternatively, external thread portions may be formed in the guide members and internal thread portions may be formed in the rotor shaft, thereby the above-mentioned internal and external threads are configured as an electric valve in opposite ways.

[0065] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, and other embodiments have also been described in detail. However, the specific structure is not limited to the above embodiments. The present invention also includes design changes and the like that that do not depart from the spirit of the present invention.

Claims

1. An electric valve, wherein a needle valve is disposed on the axis of a small-diameter valve port, and the rotational motion of an electric motor rotor is converted into linear motion by a threaded feed mechanism to cause the needle valve to move forward and backward along the axis, and the refrigerant flow rate is controlled according to the opening area between the opening of the small-diameter valve port and the slit of the needle valve. The electric valve described above is characterized in that, The main valve core is equipped with a main valve port that can change the opening of the main valve port of the valve chamber, and the aforementioned small-diameter valve port is formed on the main valve core. It has two flow control regions: a small flow control region where the needle valve changes the opening of the small-diameter valve port, and a large flow control region where the main valve core changes the opening of the main valve port. The needle valve described above has a needle valve side engagement surface that moves to the side opposite to the small-diameter valve port side and engages with the main valve core. The main valve core has a main valve core side engagement surface that engages with the needle valve. In the engagement state where the engagement surface of the needle valve side engages with the engagement surface of the main valve core side, the main valve core moves integrally with the needle valve to change the opening degree of the main valve port. The needle valve is configured such that, in the aforementioned engaged state, the front end of the needle valve remains within the aforementioned small-diameter valve port. The above-mentioned needle valve has the following features: The truncated cone-shaped portion gradually decreases in diameter towards the front end of the small-diameter valve port. A first straight section with a constant diameter is configured to connect to the base end side with the largest diameter in the aforementioned truncated cone section, and is located within the aforementioned small-diameter valve orifice when the needle valve moves to its maximum position towards the aforementioned small-diameter valve orifice side; and The second straight section with a constant diameter is connected to the smallest diameter section among the aforementioned frustum-shaped sections. The first straight section and the second straight section are arranged to sandwich the frustum-shaped section. A constant flow range is created between the terminal of the aforementioned small flow control region and the aforementioned large flow control region, maintaining a constant flow rate. In the aforementioned needle valve, the length from the engagement surface on the needle valve side to the smallest diameter portion of the truncated cone section is set to be shorter than the length from the engagement surface on the main valve core side to the upper end face of the small-diameter valve port. In the aforementioned engaged state, the smallest diameter portion of the truncated cone is located on the threaded feed mechanism side relative to the upper end face of the small diameter valve port.

2. The electric valve according to claim 1, characterized in that, Even when the needle valve moves to its maximum position toward the small-diameter valve port, it does not sit at the small-diameter valve port, thus forming a flow path between the straight section and the small-diameter valve port.

3. The electric valve according to claim 2, characterized in that, The length of the straight section of the needle valve is smaller than the outer diameter of the straight section.

4. The electric valve according to claim 2, characterized in that, The aforementioned small-diameter valve port is formed in a cylindrical shape with the aforementioned axis as its central axis. The main valve core has a tapered cylindrical portion, which has its minimum diameter opening at the end opposite to the needle valve side of the cylindrical small-diameter valve port. The boundary between the straight portion and the truncated cone portion of the needle valve is located inside the cylindrical small-diameter valve port when the needle valve moves to its maximum position toward the small-diameter valve port.

5. The electric valve according to claim 1, characterized in that, The aforementioned main valve core has: A retaining part, which is cylindrical in shape, houses the needle valve on its inner side and engages with the needle valve, which moves toward a side opposite to the small-diameter valve port side; and The main valve section is located at the end of the retaining section that is closer to the main valve port than the smaller diameter valve port. It is formed into a tapered annular shape that tapers from the portion with a diameter that is significantly larger than that of the retaining section and the main valve port to the front end with a diameter that is smaller than that of the main valve port, and changes the opening degree of the main valve port.

6. An electric valve, wherein a needle valve is disposed on the axis of a small-diameter valve port, and the rotational motion of an electric motor rotor is converted into linear motion by a threaded feed mechanism to cause the needle valve to move forward and backward along the axis, and the refrigerant flow rate is controlled according to the opening area between the opening of the small-diameter valve port and the slit of the needle valve. The electric valve described above is characterized in that, The main valve core is equipped with a main valve port that can change the opening of the main valve port of the valve chamber, and the aforementioned small-diameter valve port is formed on the main valve core. It has two flow control regions: a small flow control region where the needle valve changes the opening of the small-diameter valve port, and a large flow control region where the main valve core changes the opening of the main valve port. The needle valve and the main valve core engage with each other, and the needle valve and the main valve core have engaging portions that can be separated from each other in the direction of the aforementioned axis. The main valve core moves integrally with the needle valve in the engaged state where the engaging parts are engaged with each other, thereby changing the opening degree of the main valve port. The needle valve is configured such that, in the aforementioned engaged state, the front end of the needle valve remains within the aforementioned small-diameter valve port. The above-mentioned needle valve has the following features: The truncated cone-shaped portion gradually decreases in diameter towards the front end of the small-diameter valve port. A first straight section with a constant diameter is configured to connect to the base end side with the largest diameter in the aforementioned truncated cone section, and is located within the aforementioned small-diameter valve orifice when the needle valve moves to its maximum position towards the aforementioned small-diameter valve orifice side; and The second straight section with a constant diameter is connected to the smallest diameter section among the aforementioned frustum-shaped sections. The first straight section and the second straight section are arranged to sandwich the frustum-shaped section. A constant flow range is created between the terminal of the aforementioned small flow control region and the aforementioned large flow control region, maintaining a constant flow rate. The needle valve is configured such that the smallest diameter portion of the truncated cone portion engages with the main valve core at a position where it disengages from the small-diameter valve port in the direction of the axis, while the second straight portion remains within the small-diameter valve port. In the aforementioned engaged state, the smallest diameter portion of the truncated cone is located on the threaded feed mechanism side relative to the upper end face of the small diameter valve port.

7. The electric valve according to claim 6, characterized in that, Even when the needle valve moves to its maximum position toward the small-diameter valve port, it does not sit at the small-diameter valve port, thus forming a flow path between the straight section and the small-diameter valve port.

8. The electric valve according to claim 7, characterized in that, The length of the straight section of the needle valve is smaller than the outer diameter of the straight section.

9. The electric valve according to claim 7, characterized in that, The aforementioned small-diameter valve port is formed in a cylindrical shape with the aforementioned axis as its central axis. The main valve core has a tapered cylindrical portion, which has its minimum diameter opening at the end opposite to the needle valve side of the cylindrical small-diameter valve port. The boundary between the straight portion and the truncated cone portion of the needle valve is located inside the cylindrical small-diameter valve port when the needle valve moves to its maximum position toward the small-diameter valve port.

10. The electric valve according to claim 6, characterized in that, The aforementioned main valve core has: A retaining part, which is cylindrical in shape, houses the needle valve on its inner side and engages with the needle valve, which moves toward a side opposite to the small-diameter valve port side; and The main valve section is located at the end of the retaining section that is closer to the main valve port than the smaller diameter valve port. It is formed into a tapered annular shape that tapers from the portion with a diameter that is significantly larger than that of the retaining section and the main valve port to the front end with a diameter that is smaller than that of the main valve port, and changes the opening degree of the main valve port.

11. A refrigeration cycle system, comprising a compressor, an indoor heat exchanger, an outdoor heat exchanger, an electronic expansion valve disposed between the indoor heat exchanger and the outdoor heat exchanger, and a dehumidification valve disposed in the indoor heat exchanger. The above-mentioned refrigeration cycle system is characterized in that, The electric valve described in claim 1 or 6 is used as the dehumidification valve described above.

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