Motor-operated valve and refrigeration cycle system

Abstract

To suppress variations in the maximum flow rate of a small flow rate control area, and to make a control possible range in the small flow rate control area wide, in an electric valve performing small flow rate control with a needle valve 4.SOLUTION: A needle valve 4 having a second truncated cone portion 44 gradually decreasing a diameter toward a tip end, is disposed on an axis L of an auxiliary valve port 33a. A drive portion 5 moves the needle valve 4 forward / backward on the axis. A small flow rate control area is obtained by the needle valve 4 and the auxiliary valve port 33a. A large flow rate control area is obtained by a main valve body 3 and a main valve port 13a. A second straight portion 45 with a fixed diameter is provided, which is coupled to the minimum diameter portion of the second truncated cone portion 44 of the needle valve 4. At a position where the second truncated cone portion 44 is drawn out of the auxiliary valve port 33a, the second straight portion 45 is held in the auxiliary valve port 33a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor-operated valve for use in a refrigeration cycle system and the like, and to a refrigeration cycle system. [Background technology]

[0002] Conventionally, an electric valve provided in the refrigeration cycle of an air conditioner is disclosed, for example, in Japanese Patent No. 2898906 (Patent Document 1). This electric valve is equipped with a main valve body (second valve body) that changes the opening degree of a main valve port (large diameter valve port) in a valve chamber, a sub-valve body (first valve body) that changes the opening degree of a sub-valve port (small diameter valve port) formed in the main valve body, and a drive unit having an electric motor (stepping motor) that drives the sub-valve body.

[0003] Fig. 12 is a graph showing the relationship (flow characteristic) between the drive pulse of the electric motor (lift amount of the sub-valve body) in this motor-operated valve and the flow rate of the refrigerant flowing through the motor-operated valve. In this motor-operated valve, when the main valve body is seated and the main valve port is closed, the sub-valve body changes the opening of the sub-valve port by the drive of the electric motor, and at this time, the opening of the sub-valve port is controlled according to the drive pulse of the electric motor, thereby obtaining a flow characteristic with a small flow control region as shown in Fig. 12. In addition, when the sub-valve body is lifted by the drive of the electric motor, it engages with the main valve body, and when the main valve body is lifted together with the sub-valve body, the main valve port opens, and when the main valve body changes the opening of the main valve port, it obtains a flow characteristic with a large flow control region as shown in Fig. 12. In this way, this motor-operated valve has two flow control regions, a small flow control region and a large flow control region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2898906 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional motor-operated valves, even if multiple motor-operated valves are manufactured to have the target flow characteristics shown by the solid line in Figure 13, the flow characteristics vary due to variations in part dimensions, etc. The range of variation is affected by the dimensional tolerances of parts and assembly tolerances, and for example, in the example of Figure 13, the flow characteristics are as shown by the upper limit shown by the dotted line and the lower limit shown by the dashed line, compared to the center flow characteristics shown by the solid line. In addition, there is a bending point at the boundary between the small flow control area and the large flow control area in the flow characteristics, and the position of this bending point also varies. Therefore, in order to control the pulse of the motor-operated valve, it is necessary to set the upper limit of the drive pulse smaller than the drive pulse (point A in Figure 13) at which the upper limit of the drive pulse in the small flow control area is the smallest within the variation range, and to set the range up to that upper limit as the micro flow controllable range actually used for micro flow control.

[0006] Furthermore, even at point A in FIG. 13, there is variation in the flow rate, and for example, at the upper limit of the flow rate characteristics (flow rate characteristics of the dotted line), the valve opening is too large and the flow rate may not be fully throttled. For this reason, it is necessary to lower the upper limit of the range in which the small flow rate is controlled even further than point A, and set that range as the range in which the small flow rate is controlled. In this way, with conventional motor-operated valves, the range in which control is possible at a small flow rate must be narrowed. This is not limited to those that perform two-stage control using a main valve body and a sub-valve body, but is also a problem with motor-operated valves that control the flow rate using the truncated cone part of a needle valve. For example, the variation in the maximum flow rate in the small flow rate control range may become large, making it possible to fully throttle the flow rate, and the micro flow rate controllable range, which is the range of the drive pulse used to control the small flow rate in the small flow rate control range, must be narrowed in consideration of the variation in the flow rate.

[0007] The present invention aims to suppress variations in maximum flow rate in the small flow rate control range in an electrically operated valve that performs small flow rate control using a needle valve, and to widen the range of small flow rate control that can actually be used for small flow rate control. [Means for solving the problem]

[0008] The motor-operated valve of claim 1 is a motor-operated valve in which a needle valve is arranged on the axis of a small diameter valve port, and the needle valve is advanced and retreated in the axial direction by converting the rotational motion of a rotor of an electric motor into linear motion using a screw feed mechanism, thereby controlling the flow rate of a refrigerant by the opening area of ​​a gap between an opening of the small diameter valve port and the needle valve, the motor-operated valve further comprises a main valve body that changes the opening degree of a main valve port of a valve chest, and the small diameter valve port is formed in the main valve body, the needle valve has two flow rate control regions, namely, a small flow rate control region in which the needle valve changes the opening degree of the small diameter valve port, and a large flow rate control region in which the main valve body changes the opening degree of the main valve port, the needle valve engages with the main valve body and has a needle valve side abutment surface that is separable from the main valve body in the axial direction, the main valve body has a main valve body side abutment surface that engages with the needle valve, and the needle valve side abutment surface and the main valve body side abutment surface are engaged with each other. the needle valve is configured to move integrally with the needle valve in an engaged state to change the opening degree of the main valve port, the needle valve having a truncated cone portion having a diameter gradually decreasing toward a tip end thereof on the side of the small diameter valve port, and a straight portion of a constant diameter connected to a base end side of the truncated cone portion having a diameter greatest, the needle valve being positioned within the small diameter valve port when the needle valve moves to the small diameter valve port side, the needle valve does not seat on the small diameter valve port even when it moves to the small diameter valve port side, a flow passage is formed between the straight portion and the small diameter valve port, the small diameter valve port is formed in a cylindrical shape with the axis as a center axis, in the engaged state, an end face of the tip portion of the needle valve on the side of the main valve port is located at a position away from the screw feed mechanism with respect to an upper end face of the small diameter valve port of the main valve body, a lower end of the straight portion and a lower end of the truncated cone portion, the lower end having the smallest diameter, are both disposed on the screw feed mechanism side with respect to an upper end surface of the small-diameter valve port, When the needle valve moves most toward the small valve port, the rotor side end of the truncated cone portion is positioned at a position away from the screw feed mechanism with respect to an upper end surface of the small valve port in the main valve body, a tapered space is formed at the end of the small valve port on the main valve port side, and the inner diameter of the tapered space expands as it approaches the main valve port.

[0009] The motor-operated valve of claim 2 is the motor-operated valve of claim 1, wherein the needle valve is Diameter The present invention is characterized in that it further comprises a second straight portion of a constant diameter connected to the minimum diameter portion where the diameter is smallest. The electric valve of claim 3 is the electric valve as described in claim 2, characterized in that, when in the engaged state, the boundary between the second straight portion and the truncated cone portion is provided on the small diameter valve port side rather than the tapered portion.

[0010] The motor-operated valve of claim 4 is the motor-operated valve according to claim 2, characterized in that the length of the straight portion of the needle valve is smaller than the outer diameter of the straight portion.

[0011] The motor-operated valve of claim 5 is the motor-operated valve of claim 1, characterized in that the main valve body is formed with a tapered tubular portion whose smallest diameter portion is an end opening on the opposite side to the needle valve side of the cylindrical small-diameter valve port. Another motor-operated valve is characterized in that, in the motor-operated valve according to claim 1, the main valve body is formed in a cylindrical shape, the needle valve is arranged inside, and a holding portion with which the needle valve moves opposite to the small-diameter valve port side engages, and a main valve portion is located at an end of the holding portion closer to the main valve port than the small-diameter valve port, and is formed in a tapered annular shape tapering from a portion expanded to a diameter larger than the holding portion and the main valve port to a tip portion having a diameter smaller than the main valve port, and changes the opening degree of the main valve port. The refrigeration cycle system of claim 6 is 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 dehumidification valve provided in the indoor heat exchanger, and is characterized in that the electric valve described in claim 1 is used as the dehumidification valve. Effect of the Invention

[0012] According to the motor-operated valve described above, the flow rate of the refrigerant in the small flow rate control range is controlled by the opening area of ​​the gap between the opening of the small diameter valve port and the truncated cone of the needle valve, but this needle valve has a straight section of constant diameter connected to the minimum diameter section of the truncated cone, and the straight section is held within the small diameter valve port at the position where the minimum diameter section of the truncated cone exits the small diameter valve port, so that the constant flow rate range is reached from the end of the small flow rate control range. Therefore, it is possible to suppress the variation in the maximum flow rate in the small flow rate control range and prevent the phenomenon in which the flow rate at the maximum flow rate cannot be throttled, and it is possible to widen the range in which the small flow rate controllable range, which is the range of the drive pulse actually used to control the small flow rate, and to improve the controllability of the small flow rate controllable range.

[0013] According to the above refrigeration cycle system, the same effects as those of the above motor-operated valve can be obtained. [Brief description of the drawings]

[0014] [Figure 1] 1 is a vertical sectional view of a motor-operated valve according to a first embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a main portion of the motor-operated valve of the first embodiment when the needle valve is located at a position closest to the sub-valve port. [Diagram 3] 4 is an enlarged cross-sectional view of a main portion of the motor-operated valve of the first embodiment when the needle valve is located between a position closest to the sub-valve port and a position where it engages with the main valve body. FIG. [Figure 4] 3 is an enlarged cross-sectional view of a main portion of the motor-operated valve of the first embodiment when the needle valve is in a position where it engages with the main valve body. FIG. [Diagram 5] FIG. 2 is an enlarged cross-sectional view of a main portion of the motor-operated valve according to the first embodiment, showing a fully open state of a main valve body. [Figure 6] 4 is a graph showing the relationship between the pulse amount of a drive pulse and a flow rate in the motor-operated valve of the first embodiment. [Figure 7] FIG. 4 is a vertical sectional view of a motor-operated valve according to a second embodiment of the present invention. [Figure 8] FIG. 11 is an enlarged cross-sectional view of a main portion showing a needle valve corresponding to the lowest end position of a magnet rotor in a second embodiment. [Figure 9] FIG. 11 is an enlarged cross-sectional view of a main portion illustrating a state in which a refrigerant flows through a gap between a second truncated cone portion of a needle valve and a valve port in a second embodiment. [Figure 10] FIG. 11 is an enlarged cross-sectional view of a main portion of a needle valve according to a second embodiment, showing a state in which a second straight portion is positioned within a valve port. [Figure 11] 1 is a diagram showing a refrigeration cycle system according to an embodiment; [Figure 12] 1 is a graph showing the relationship between the pulse amount of a drive pulse and a flow rate in a conventional motor-operated valve. [Figure 13] FIG. 1 is a diagram for explaining problems in the conventional art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Next, an embodiment of the motor-operated valve and the refrigeration cycle system of the present invention will be described with reference to the drawings. Fig. 1 is a longitudinal sectional view of the motor-operated valve of the first embodiment, Fig. 2 is an enlarged sectional view of the main part of the motor-operated valve of the first embodiment when the needle valve is at the position closest to the auxiliary valve port, Fig. 3 is an enlarged sectional view of the main part of the motor-operated valve of the first embodiment when the needle valve is between the position closest to the auxiliary valve port and the position where it engages with the main valve body, Fig. 4 is an enlarged sectional view of the main part of the motor-operated valve of the first embodiment when the needle valve is at the position where it engages with the main valve body, and Fig. 5 is an enlarged sectional view of the main part showing the fully open state of the main valve body of the motor-operated valve of the first embodiment. The concept of "upper and lower" in the following description corresponds to the upper and lower in the drawings of Figs. 1 to 4. This motor-operated valve 100 includes a valve housing 1, a guide member 2, a main valve body 3, a needle valve 4, and a drive unit 5.

[0016] The valve housing 1 is formed in a substantially cylindrical shape from, for example, brass, stainless steel, or the like, and has a valve chamber 1R inside. A first joint pipe 11 that is connected to the 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. A cylindrical main valve seat 13 is formed on the valve chamber 1R side of the second joint pipe 12, and the inside of this main valve seat 13 is a main valve port 13a, and the second joint pipe 12 is connected to 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. The first joint pipe 11 and the second joint pipe 12 are fixed to the valve housing 1 by brazing or the like.

[0017] A guide member 2 is attached to the opening at the upper end of the valve housing 1. The guide member 2 has a press-fit portion 21 that is press-fitted into the inner peripheral surface of the valve housing 1, a substantially cylindrical guide portion 22 located inside the press-fit portion 21, a holder portion 23 that extends from the upper portion of the guide portion 22, and a ring-shaped flange portion 24 located on the outer periphery of the guide portion 22. The press-fit portion 21, the guide portion 22, and the holder portion 23 are configured as an integrated resin product. The flange portion 24 is a metal plate such as brass or stainless steel, and is provided integrally with the resin press-fit portion 21 and the holder portion 22 by insert molding.

[0018] The guide member 2 is assembled to the valve housing 1 and fixed by welding to the upper end of the valve housing 1 via a flange portion 24. In the guide member 2, a cylindrical guide hole 22a coaxial with the axis L is formed in the guide portion 22, and a female threaded portion 23a coaxial with the guide hole 22a and a threaded hole thereof are formed in the center of the holder portion 23. The main valve element 3 is disposed in the guide hole 22a of the holder portion 23.

[0019] The main valve element 3 has a main valve portion 31 that is seated on and released from the main valve seat 13, a holding portion 32 having a cylindrical needle guide hole 32a, and an auxiliary valve seat 33. A washer 46 and a guide boss portion 47 attached to a valve shaft 41 described later are inserted into the needle guide hole 32a of the holding portion 32, and a ring-shaped retainer 321 is fixed to the upper end of the holding portion 32 by fitting and fixing, welding, or the like. The upper outer periphery of the holding portion 32 has a reduced diameter, and a main valve spring 3a is disposed between the upper outer periphery of the holding portion 32 and the upper end of the guide hole 22a, and the main valve element 3 is biased toward the main valve seat 13 (closing direction) by the main valve spring 3a. The auxiliary valve seat 33 is located at the lower end of the needle guide hole 32a, and an auxiliary valve port 33a is formed in the center of the auxiliary valve seat 33 as a "small diameter valve port". The sub-valve port 33a has a circular shape centered on the axis L. Furthermore, a communication hole 32b that communicates between the needle guide hole 32a and the valve chamber 1R is formed in at least one location on the side surface of the retaining portion 32. When the needle valve 4 opens the sub-valve port 33a as described below, the valve chamber 1R, the needle guide hole 32a, the sub-valve port 33a, and the main valve port 13a communicate with each other.

[0020] The needle valve 4 includes a valve shaft 41 integrally formed with a rotor shaft 51 at the lower end thereof and connected to the rotor shaft 51, a first truncated cone portion 42 connected to the valve shaft 41, 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. The needle valve 4 also includes an annular washer 46 disposed on the valve shaft 41 and a guide boss portion 47 fixed to the valve shaft 41. The guide boss portion 47 is fixed separately from the valve shaft 41, but the guide boss portion 47 may be formed integrally with the valve shaft 41. The "frustum cone portion" and the "straight portion" in the present invention correspond to the second truncated cone portion 44 and the second straight portion 45, respectively. The first straight portion 43 has a diameter that is aligned with the sub-valve port 33a and can be inserted into the sub-valve port 33a, and its side surface has the same diameter in the direction of the axis L. The apex angle of the second truncated cone portion 44 (the angle between generatrix lines spaced 180° apart around the axis L) is smaller than the apex angle of the first truncated cone portion 42. The diameter of the side surface of the second straight portion 45 is smaller than the diameter of the sub-valve port 33a and is the same diameter in the direction of the axis L. The washer 46 and the guide boss portion 47 are slidably inserted into the needle guide hole 32a.

[0021] A case 14 is airtightly fixed to the upper end of the valve housing 1 by welding or the like, and a drive unit 5 is configured inside and outside this case 14. The drive unit 5 includes a stepping motor 5A as an "electric motor," a screw feed mechanism 5B that moves the needle valve 4 forward and backward by the rotation of the stepping motor 5A, and a stopper mechanism 5C that regulates the rotation of the stepping motor 5A.

[0022] The stepping motor 5A is composed of a rotor shaft 51, a magnet rotor 52 rotatably disposed inside the case 14, a stator coil 53 disposed facing the magnet rotor 52 on the outer periphery of the case 14, and other components such as a yoke and exterior members (not shown). The rotor shaft 51 is attached to the center of the magnet rotor 52 via a bush, and a male thread portion 51a is formed on the outer periphery of the rotor shaft 51 on the guide member 2 side. The male thread portion 51a is screwed into the female thread portion 23a of the guide member 2, so that the guide member 2 supports the rotor shaft 51 on the axis L. The female thread portion 23a of the guide member 2 and the male thread portion 51a of the rotor shaft 51 constitute a screw feed mechanism 5B.

[0023] With the above configuration, the magnet rotor 52 and the rotor shaft 51 are rotated by driving the stepping motor 5A, and the rotor shaft 51 moves in the axial direction L by the screw feed mechanism 5B between the male thread portion 51a of the rotor shaft 51 and the female thread portion 23a of the guide member 2. Then, the needle valve 4 moves forward and backward in the axial direction L, and the needle valve 4 approaches or moves away from the auxiliary valve port 33a. This controls the opening degree of the auxiliary valve port 33a. In addition, the needle valve 4 (washer 46) engages with the main valve body 3 (retainer 321), and the main valve body 3 moves together with the needle valve 4 to seat on and unseat from the main valve seat 13. This controls the flow rate of the refrigerant flowing from the first joint pipe 11 to the second joint pipe 12, or from the second joint pipe 12 to the first joint pipe 11. A protrusion 52a is formed on the magnet rotor 52, and as the magnet rotor 52 rotates, the protrusion 52a activates the rotation stopper mechanism 5C, restricting the lowermost and uppermost positions of the rotor shaft 51 (and the magnet rotor 52). Figures 1 and 2 show the rotor shaft 51 (and the magnet rotor 52) in the lowermost position.

[0024] FIG. 6 is a graph showing the relationship between the pulse amount (=valve opening degree) of the drive pulse in the stepping motor 5A and the flow rate, and the detailed operation of the motor-operated valve 100 will be described with reference to FIGS.

[0025] The motor-operated valve 100 described above operates as follows. First, in the state shown in Fig. 2 (and Fig. 1), the main valve portion 31 of the main valve element 3 is seated on the main valve seat 13, and the main valve port 13a is closed, resulting in a valve-closed state. On the other hand, the needle valve 4 closest to the sub-valve port 33a has the first straight portion 43 inserted into the sub-valve port 33a, but this needle valve 4 is not seated on the sub-valve seat 33, and a small amount of refrigerant flows through the gap between the outer circumferential surface of the first straight portion 43 and the sub-valve port 33a. That is, as shown in Fig. 6, even when the drive pulse is at the reference point (zero point), a small amount of refrigerant flows.

[0026] Next, the stepping motor 5A is driven to rotate the magnet rotor 52 to raise the needle valve 4, so that the first straight portion 43 of the needle valve 4 comes out of the sub-valve port 33a as shown in FIG. 3, and a flow path is formed by the gap between the second truncated cone portion 44 of the needle valve 4 and the sub-valve port 33a. Here, the diameter of the second truncated cone portion 44 gradually decreases, so the gap between the second truncated cone portion 44 and the sub-valve port 33a increases, and the flow path is enlarged, so that the flow rate gradually increases as shown in FIG. 6. At this time, since the main valve portion 31 of the main valve body 3 remains seated on the main valve seat 13, the increase in the flow rate is small until the second truncated cone portion 44 of the needle valve 4 comes out of the sub-valve port 33a. The control region in which the needle valve 4 is moved between the position closest to the sub-valve port 33a and the position where the second truncated cone portion 44 comes out of the sub-valve port 33a to change the opening degree of the sub-valve port 33a is the small flow control region. In this small flow rate control region, the change in flow rate relative to the pulse amount (=valve lift amount) of the drive pulse of stepping motor 5A is smaller than in the large flow rate control region.

[0027] Next, as shown in Fig. 4, when the needle valve 4 is raised to a position where it engages with the main valve element 31 and the washer 46 is engaged with the main valve element 3, the main valve element 3 rises together with the needle valve 4. When it is further raised, the main valve element 3 is pulled up by the valve stem 41 (and the washer 46) as shown in Fig. 5, and the main valve portion 31 separates from the main valve seat 13 to open the valve. The control region in which the main valve element 3 is raised from the seating position (closed position) to the valve open position (open position) in this way is the large flow control region, and the change in flow rate relative to the pulse amount (=valve lift amount) of the drive pulse of the stepping motor 5A in this large flow control region is large. The flow rate is maximum in the fully open state in which the main valve element 3 is raised to the valve open position shown in Fig. 5. In addition, the flow rate in the fully open state is set so that the opening area of ​​the gap between the main valve portion 31 and the main valve seat 13 is equal to or greater than the opening area of ​​the primary joint pipe 11 and the secondary joint pipe 12, and the flow rate is not restricted by the main valve portion 31 or the main valve port 13a, i.e., the electric valve 100 functions as a simple flow path.

[0028] Here, there is a moment when the boundary portion (the minimum diameter portion of the cone frustum) between the second truncated cone portion 44 and the second straight portion 45 of the needle valve 4 comes out of the sub-valve port 33a from the position shown in FIG. 3 to the position shown in FIG. 4. From this moment to the position shown in FIG. 4, only the second straight portion 45 is located in the sub-valve port 33a, and the opening area of ​​the gap between the sub-valve port 33a and the second straight portion 45 is constant. For this reason, as shown in FIG. 6, a constant flow rate region where a constant flow rate is maintained is generated between the end of the small flow rate control region and the large flow rate control region. Therefore, according to the present motor-operated valve 100, it is possible to suppress the variation of the maximum flow rate in the small flow rate control region, and it is possible to sufficiently narrow the flow rate at the maximum flow rate in the sub-valve port 33a. In addition, it is possible to widen the micro flow rate controllable range, which is the range of the drive pulse actually used to control the micro flow rate, and to improve the controllability of the micro flow rate controllable range.

[0029] Fig. 7 is a vertical cross-sectional view of the motor-operated valve of the second embodiment, Fig. 8 is an enlarged cross-sectional view of a main part showing a needle valve corresponding to the lowest end position of the magnet rotor in the second embodiment, Fig. 9 is an enlarged cross-sectional view of a main part showing a state in which refrigerant flows through a gap between the second truncated cone part of the needle valve and the valve port in the second embodiment, and Fig. 10 is an enlarged cross-sectional view of a main part showing a state in which the second straight part of the needle valve in the second embodiment is positioned within the valve port. Note that the concepts of "upper and lower" in the following explanation correspond to the upper and lower in the drawing of Fig. 7.

[0030] The motor-operated valve 200 includes a valve housing 10, a guide member 20, a valve holder portion 30, a needle valve 40, and a drive portion 50.

[0031] The valve housing 10 is formed in a substantially cylindrical shape from, for example, brass, stainless steel, or the like, and has a valve chamber 10R inside. A first joint pipe 110 that is connected to the valve chamber 10R is connected to one side of the outer periphery of the valve housing 10, and a second joint pipe 120 is connected to a cylindrical portion extending downward from the lower end. A valve seat member 130 is fitted to the valve chamber 10R side of the second joint pipe 120. The inside of the valve seat member 130 is a valve port 130a as a "small diameter valve port", and the second joint pipe 120 is connected to the valve chamber 10R through the valve port 130a. The valve port 130a is a cylindrical through hole centered on the axis L. The first joint pipe 110 and the second joint pipe 120 are fixed to the valve housing 10 by brazing or the like.

[0032] A guide member 20 is attached to the opening at the upper end of the valve housing 10. The guide member 20 has a press-fit portion 210 that is press-fitted into the inner peripheral surface of the valve housing 10, a substantially cylindrical guide portion 220 located inside the press-fit portion 210, a holder portion 230 that extends from the upper portion of the guide portion 220, and a ring-shaped flange portion 240 located on the outer periphery of the guide portion 220. The press-fit portion 210, the guide portion 220, and the holder portion 230 are configured as an integrated resin product. The flange portion 240 is a metal plate such as brass or stainless steel, and is provided integrally with the resin press-fit portion 210 and the holder portion 220 by insert molding.

[0033] The guide member 20 is assembled to the valve housing 10 and fixed by welding to the upper end of the valve housing 10 via a flange portion 240. In the guide member 20, a cylindrical guide hole 220a coaxial with the axis L is formed in the guide portion 220, and a female screw portion 230a coaxial with the guide hole 220a and a screw hole for the female screw portion 230a are formed in the center of the holder portion 230. A valve holder portion 30 and a needle valve 40 are provided in the guide member 20 and the valve chamber 10R.

[0034] The valve holder 30 includes an annular thrust washer 310, a cylindrical guide tube 320, a spring bearing 330, and a coil spring 340. The guide tube 320 has an annular ceiling portion 320a formed by bending the upper end portion inward. On the other hand, a rotor shaft 510 described later has a boss portion 511 at an end portion lower than the male thread portion 510a, and a flange portion 512 is integrally formed with the boss portion 511. The boss portion 511 is fitted into the ceiling portion 320a to attach the thrust washer 310. In addition, a spring bearing 330 is provided in the guide tube 320 so as to be movable in the direction of the axis L, and the needle valve 40 is fixed to the lower end portion of the guide tube 320 with the spring bearing 330 and the coil spring 340 housed therein.

[0035] The needle valve 40 includes a boss portion 410 fixed to the guide tube 320, a first truncated cone portion 420 formed at the lower portion of the boss portion 410, a first straight portion 430 connected to the first truncated cone portion 420, a second truncated cone portion 440 connected to the first straight portion 430, and a second straight portion 450 connected to the second truncated cone portion 440, which are integrally formed. Note that the "frustum cone portion" and the "straight portion" in the present invention correspond to the second truncated cone portion 440 and the second straight portion 450, respectively. The first straight portion 430 has a diameter that can be inserted into the valve port 130a by matching with the valve port 130a, and its side surface has the same diameter in the direction of the axis L. In addition, the apex angle of the second truncated cone portion 440 (the angle between the generatrix lines spaced apart by 180° around the axis L) is smaller than the apex angle of the first truncated cone portion 420. Further, the diameter of the side surface of the second straight portion 450 is smaller than the diameter of the valve port 130a, and they are the same diameter in the axial L direction.

[0036] A case 140 is airtightly fixed to the upper end of the valve housing 10 by welding or the like, and a drive unit 50 is configured inside and outside this case 140. The drive unit 50 includes a stepping motor 50A as an "electric motor," a screw feed mechanism 50B that moves the needle valve 40 forward and backward by the rotation of the stepping motor 50A, and a stopper mechanism 50C that regulates the rotation of the stepping motor 50A.

[0037] The stepping motor 50A is composed of a rotor shaft 510, a magnet rotor 520 rotatably disposed inside the case 140, a stator coil 530 disposed facing the magnet rotor 520 on the outer periphery of the case 140, and other components such as a yoke and an exterior member (not shown). The rotor shaft 510 is attached to the center of the magnet rotor 520 via a bush, and a male thread portion 510a is formed on the outer periphery of the rotor shaft 510 on the guide member 20 side. The male thread portion 510a is screwed into the female thread portion 230a of the guide member 20, so that the guide member 20 supports the rotor shaft 510 on the axis L. The female thread portion 230a of the guide member 20 and the male thread portion 510a of the rotor shaft 510 constitute a screw feed mechanism 50B.

[0038] With the above configuration, the magnet rotor 520 and the rotor shaft 510 are rotated by driving the stepping motor 50A, and the rotor shaft 510 moves in the direction of the axis L by the screw feed mechanism 50B between the male thread portion 510a of the rotor shaft 510 and the female thread portion 230a of the guide member 20. Then, the needle valve 40 moves forward and backward in the direction of the axis L, and the needle valve 40 approaches or moves away from the valve port 130a. This controls the opening degree of the valve port 130a, and controls the flow rate of the refrigerant flowing from the first joint pipe 110 to the second joint pipe 120, or from the second joint pipe 120 to the first joint pipe 110. The magnet rotor 520 has a protrusion 520a formed thereon, and as the magnet rotor 520 rotates, the protrusion 520a activates the rotation stopper mechanism 50C, and the lowest end position and the highest end position of the rotor shaft 510 (and the magnet rotor 520) are restricted. 7 and 8 show the rotor shaft 510 (and the magnet rotor 520) in the lowest position.

[0039] The motor-operated valve 200 described above operates as follows: First, in the state shown in Figures 7 and 8, the needle valve 40 located closest to the valve port 130a has the first straight portion 430 inserted into the valve port 130a, and a small amount of refrigerant flows through the gap between the outer circumferential surface of the first straight portion 430 and the valve port 130a.

[0040] Next, the stepping motor 50A is driven to rotate the magnet rotor 520 to raise the needle valve 40, so that the first straight portion 430 of the needle valve 40 comes out of the valve port 130a, as shown in Fig. 9, 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, so the gap between the valve port 130a and the valve port 130a increases, and the flow path is expanded, so that the flow rate gradually increases as in Fig. 6, but in this state, the increase in the flow rate is small. In this way, the control region in which the opening degree is changed according to the gap between the second truncated cone portion 440 of the needle valve 40 and the valve port 130a is the small flow rate control region, and the change in flow rate relative to the pulse amount (=valve lift amount) of the drive pulse of the stepping motor 50A in this small flow rate control region is smaller than that in the large flow rate control region.

[0041] Here, there is a moment when the boundary portion (the minimum diameter portion of the cone frustum) between the second truncated cone portion 440 and the second straight portion 450 of the needle valve 40 comes out of the valve port 130a from the position shown in FIG. 9 to the position shown in FIG. 10. From this moment, only the second straight portion 450 is located in the valve port 130a, and the opening area of ​​the gap between the valve port 130a and the second straight portion 450 is constant. When the second straight portion 450 comes out of the valve port 130a, the flow rate increases rapidly toward the fully open state, and a large flow rate control region is created. As a result, a constant flow rate region where a constant flow rate is maintained is created between the end of the small flow rate control region and the large flow rate control region. Therefore, according to the present motor-operated valve 200, it is possible to suppress the variation in the maximum flow rate in the small flow rate control region, and it is possible to sufficiently narrow the flow rate at the maximum flow rate in the valve port 130a. In addition, it is possible to widen the micro flow rate controllable range, which is the range of the drive pulse actually used to control the micro flow rate, and it is possible to improve the controllability of the micro flow rate controllable range.

[0042] Next, the refrigeration cycle system of the present invention will be described with reference to FIG. 11. This refrigeration cycle system is used, for example, in an air conditioner such as a home air conditioner. The motor-operated valve 100 of the first embodiment is provided as a "dehumidification control valve" between the first indoor heat exchanger 91 (operating as a cooler during dehumidification) and the second indoor heat exchanger 92 (operating as a heater during dehumidification). The motor-operated valve 200 of the second embodiment is provided as an "electronic expansion valve" between the second indoor heat exchanger 92 and the outdoor heat exchanger 93. The motor-operated valve 100, the motor-operated valve 200, the outdoor heat exchanger 93, the compressor 94, and the four-way valve 95 constitute a heat pump type refrigeration cycle. The first indoor heat exchanger 91, the second indoor heat exchanger 92, and the motor-operated valve 100 are installed indoors, and the outdoor heat exchanger 93, the compressor 94, the four-way valve 95, and the motor-operated valve 200 are installed outdoors, forming a heating and cooling device.

[0043] In the motor-operated valve 100 of the first embodiment as a dehumidification valve, during cooling or heating other than dehumidification, the main valve body is fully opened, and the first indoor heat exchanger 91 and the second indoor heat exchanger 92 are combined into one indoor heat exchanger. The combined indoor heat exchanger and outdoor heat exchanger 93 function alternatively as an "evaporator" and a "condenser." In other words, the motor-operated valve 200 as an electronic expansion valve is provided between the evaporator and the condenser.

[0044] In the above embodiment, the guide members 2, 20 are formed with female threads 23a, 230a, and the rotor shafts 51, 510 are formed with male threads 51a, 510a to form a screw feed mechanism, but this combination of threads is not limited to this. Conversely, the guide members may be formed with male threads, and the rotor shaft may be formed with female threads, so that the electric valve has the female threads and male threads in a reverse arrangement to that described above.

[0045] The above describes in detail the embodiments of the present invention with reference to the drawings, and also describes in detail other embodiments. However, the specific configuration is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention. [Explanation of symbols]

[0046] 1 Valve housing 1R valve chamber 11 First joint pipe 12 Second joint pipe 13 Main valve seat 13a Main valve port L axis 2 Guide member 21 Press-fit section 22 Guide section 22a Guide hole 23 Holder part 23a Female thread 24 Flange 3 Main valve body 3a Main valve spring 31 Main valve section 32 Holding part 33 Sub-valve seat 33a Sub-valve port (small diameter valve port) 4 Needle Valve 41 Valve stem 42 First cone 43 First Straight Section 44 Second truncated cone (frustum cone) 45 Second straight section (straight section) 46 Washer 47 Guide boss 5 Drive unit 5A stepping motor (electric motor) 51 Rotor shaft 51a Male thread 52 Magnet rotor 52a Protrusion 53 Stator coil 5B Screw feed mechanism 5C Stopper mechanism 10 Valve housing 10R valve chamber 110 First joint pipe 120 Second joint pipe 130 Valve seat material 130a Valve port (small diameter port) 20 Guide member 210 Press-fit part 220 Guide section 220a Guide hole 230 Holder part 230a Female thread 240 Flange part 30 Valve holder part 40 Needle valve 410 Boss part 420 First cone 430 First Straight Section 440 Second truncated cone (frustum cone) 450 Second straight section (straight section) 50 Drive unit 50A stepping motor (electric motor) 510 Rotor shaft 510a Male thread 520 Magnet rotor 530 Stator coil 511 Boss 512 Flange part 50B Screw feed mechanism 50C Stopper mechanism 91 No. 1 indoor heat exchanger 92 Second indoor heat exchanger 93 Outdoor heat exchanger 94 Compressor 95 Four-way valve 100 Motor-operated valve 200 Motor-operated valve

Claims

1. A motor-operated valve in which a needle valve is disposed on the axis of a small-diameter valve port, and a rotational motion of a rotor of an electric motor is converted into a linear motion by a screw feed mechanism to move the needle valve back and forth in the axial direction, thereby controlling a flow rate of a refrigerant by an opening area of ​​a gap between an opening of the small-diameter valve port and the needle valve, a main valve body for changing the opening degree of a main valve port of a valve chest, the small diameter valve port being formed in the main valve body, the needle valve having a small flow rate control region for changing the opening degree of the small diameter valve port, and a large flow rate control region for changing the opening degree of the main valve port by the main valve body, the needle valve has a needle valve side abutment surface that is engaged with the main valve body and is movable in contact with and away from the main valve body in the axial direction, The main valve body has a main valve body side abutment surface that engages with the needle valve, the needle valve abutment surface and the main valve body abutment surface are engaged with each other and move together to change the opening degree of the main valve port, the needle valve comprises a truncated cone portion having a diameter gradually decreasing toward a tip end on the small-diameter valve port side, and a straight portion of a constant diameter connected to a base end side of the truncated cone portion where the diameter is largest, the straight portion being located within the small-diameter valve port when the needle valve moves to the furthest position toward the small-diameter valve port, the needle valve does not seat on the small-diameter valve port even when it moves to the small-diameter valve port side to the maximum extent, and a flow passage is formed between the straight portion and the small-diameter valve port, The small diameter valve port is formed in a cylindrical shape with the axis line as a central axis, In the engaged state, an end face of the tip portion of the needle valve on the main valve port side is located at a position away from the screw feed mechanism with respect to an upper end face of the small-diameter valve port of the main valve body, and both a lower end of the straight portion and a lower end of the truncated cone portion, which has the smallest diameter, are located on the screw feed mechanism side with respect to an upper end face of the small-diameter valve port, when the needle valve moves most toward the small-diameter valve port, an end portion of the truncated cone portion on the rotor side is disposed at a position farther from the screw feed mechanism than an upper end surface of the small-diameter valve port of the main valve body, A tapered space is formed at an end of the small-diameter valve port on the main valve port side, An electrically operated valve, wherein the inner diameter of the tapered space increases as it approaches the main valve port.

2. 2. The motor-operated valve according to claim 1, wherein the needle valve further comprises a second straight portion having a constant diameter and connected to a minimum diameter portion of the truncated cone portion, the minimum diameter portion being the smallest in diameter.

3. 3. The motor-operated valve according to claim 2, wherein in the engaged state, a boundary between the second straight portion and the truncated cone portion is provided on the small-diameter valve port side relative to the tapered space.

4. 2. The motor-operated valve according to claim 1, wherein a length of the straight portion of the needle valve is smaller than an outer diameter of the straight portion.

5. 3. The motor-operated valve according to claim 2, wherein the main valve body is formed with a tapered tubular portion having a minimum diameter at an end opening on an opposite side to the needle valve side of the cylindrical small-diameter valve port.

6. 13. 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 dehumidification valve provided in the indoor heat exchanger, wherein the motor-operated valve according to claim 1 is used as the dehumidification valve.

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