Electric valve

Abstract

To provide a motor valve capable of improving the degree of freedom in controlling an on-off valve while securing a smaller size and a lighter weight.SOLUTION: The motor valve includes a valve body including a first flow path into which refrigerant is introduced, a second flow path out of which the refrigerant flows, a third flow path through which the refrigerant passes, and a valve seat formed between the first flow path and the second flow path, a valve stem body including a valve element part which can be seated on the valve seat, a motor arranged on the valve body on the opposite side to the valve seat across the third flow path, and a conversion mechanism for converting the rotation of a rotor of the motor into linear movement to be transmitted to the valve stem body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0004] , , , , , , , , , , , , , ,

[0005]

[0001] The present invention relates to an electric valve.

Background Art

[0002] For example, in a refrigeration cycle used in an air conditioner mounted on an automobile, a temperature-sensitive thermostatic expansion valve that adjusts the amount of refrigerant passing through according to temperature is used. In such a thermostatic expansion valve, conventionally, a power element that drives a valve body with the pressure of the enclosed operating gas has been adopted.

[0003] Generally, the power element is useful in that it can sense the temperature of the refrigerant with a simple mechanical structure and perform opening and closing valve control of the expansion valve. However, in recent refrigeration cycles, more flexible opening and closing valve control is desired. For example, a forced closing valve operation may be required regardless of the temperature of the refrigerant. Therefore, a configuration in which a solenoid valve and an expansion valve are arranged in series during the refrigeration cycle and the flow of refrigerant passing through the expansion valve is blocked by the shut-off operation of the solenoid valve has already been put into practical use, but the use of two valve devices has led to an increase in the size of the structure.

[0004] On the other hand, Patent Document 1 discloses an electric valve that is combined from a valve unit and a passage body and can perform an opening and closing valve operation using a stepping motor of the valve unit. Such an electric valve can be used as an expansion valve of a refrigeration cycle, and by communicating with an external device, the stepping motor can be operated regardless of the temperature of the refrigerant, and the valve body can be arbitrarily moved away from and close to the valve seat of the passage body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the electric valve described in Patent Document 1, the valve unit is positioned in contact with the passage through which high-pressure refrigerant flows, which is provided in the passage body. In such a structure, the internal pressure of the can covering the rotor etc. increases when high-pressure refrigerant is introduced, so it is necessary to improve the strength of the can and fastening members and improve the pressure resistance of the seal, which leads to an increase in the size and weight of the structure.

[0007] Therefore, the present invention aims to provide an electric valve that can improve the degree of freedom in valve on / off control while ensuring miniaturization and weight reduction. [Means for solving the problem]

[0008] To achieve the above objective, the electric valve according to the present invention is A valve body comprising a first passage through which refrigerant is introduced, a second passage for discharging refrigerant, a third passage for passing refrigerant, and a valve seat formed between the first and second passages, A valve stem body having a valve body portion that can seat on the valve seat, A motor is provided on the valve body on the opposite side of the third flow path from the valve seat, The motor has a conversion mechanism that converts the rotation of the rotor into linear motion and transmits it to the valve shaft. death, The motor comprises a rotor, a reduction mechanism for reducing the rotation of the motor rotor, a conversion mechanism for converting the rotation reduced by the reduction mechanism into linear motion, and a can housing at least the reduction mechanism. The inside of the can is in communication with the third flow path, Between the conversion mechanism and the valve stem body, a drive member that rotates and is displaced in the axial direction, and a ball seat fixed to the valve stem body and having a spherical end are arranged. The ball fixed to the drive member contacts the end of the ball seat, thereby transmitting the axial displacement of the drive member to the valve shaft. The valve shaft comprises a first shaft having the valve body portion seated on the valve seat, and a second shaft connected to the first shaft and having the ball seat. The axis of the second axis can be tilted with respect to the axis of the first axis. It is characterized by the following: [Effects of the Invention]

[0009] The present invention provides an electric valve that can improve the degree of freedom in valve on / off control while ensuring miniaturization and weight reduction. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a side view of the electric valve in the first embodiment. [Figure 2] Figure 2 is a longitudinal sectional view of the electric valve of the first embodiment in the valve-closed state. [Figure 3] Figure 3 is a longitudinal sectional view of the electric valve of the first embodiment in the valve-open state. [Figure 4] Figure 4 is a sectional view showing the periphery of the motor unit used in the first embodiment. [Figure 5] Figure 5 is a longitudinal sectional view of the electric valve of the second embodiment in the valve-closed state. [Figure 6] Figure 6 is a longitudinal sectional view of the electric valve of the second embodiment in the valve-open state. [Figure 7] Figure 7 is a perspective view of the centering member used in the second embodiment. [Figure 8] Figure 8 is a longitudinal sectional view of the holder according to the modified example. [Figure 9] Figure 9 is a top view of the holder. [Figure 10] Figure 10 is a longitudinal sectional view of the electric valve according to the third embodiment in the valve-closed state.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

[0012] (Definition of Directions) In this specification, the direction from the valve seat 20 toward the motor unit 100 is defined as the "upward direction", and conversely, the direction from the motor unit 100 toward the valve seat 20 is defined as the "downward direction". The axis of the electric valve 1 is designated as L.

[0013] [[ID=]](First Embodiment) Figure 1 is a side view of the electric valve 1 in this embodiment as seen from the first flow path 21 side. Figure 2 is a longitudinal sectional view of the electric valve 1 in the valve-closed state, and Figure 3 is a longitudinal sectional view of the electric valve 1 in the valve-open state. Figure 4 is a sectional view showing the periphery of the motor unit 100.

[0014] In Figures 2 and 3, the electric valve 1 comprises a valve body 2, a valve shaft 3, and a motor unit 100.

[0015] The valve body 2 comprises a first passage 21, a second passage 22, a first connecting passage 21a, an orifice passage 21b, a second connecting passage 22a, and a return passage (third passage) 23. The first passage 21 and the first connecting passage 21a each extend perpendicular to the axis L, and the inner diameter of the first passage 21 is larger than the inner diameter of the first connecting passage 21a. The second passage 22 and the second connecting passage 22a each extend perpendicular to the axis L on the opposite side of the valve body 2 from the first passage 21, and the inner diameter of the second passage 22 is larger than the inner diameter of the second connecting passage 22a. The orifice passage 21b extends along the axis L, with its lower end communicating near the tip of the first connecting passage 21a and its upper end communicating near the tip of the second connecting passage 22a. The second connecting passage 22a constitutes the valve chamber VC, and the upper end of the orifice passage 21b constitutes the valve seat 20. The return passage 23 extends between the motor unit 100 and the second passage 22 in a direction intersecting the axis L. A recess 2a is formed at the upper end of the valve body 2, communicating with the return passage 23.

[0016] The first flow path 21 is a supply-side flow path connected to the condenser (not shown) of the refrigeration cycle, and high-pressure refrigerant is supplied to the orifice path 21b via the supply-side flow path. The second flow path 22 is a discharge-side flow path, and the fluid in the valve chamber VC is discharged to the evaporator (not shown) outside the electric valve via the discharge-side flow path. The refrigerant that has passed through the evaporator is introduced into the return flow path 23.

[0017] In the valve body 2, the valve stem insertion hole 28 extends upward from the second connecting passage 22a along the axis L, slidably engaging with the valve stem 3 and serving to guide the valve stem 3. Furthermore, the annular hole 27 formed above the valve stem insertion hole 28 and connected to the return passage 23 has a larger diameter than the valve stem insertion hole 28 and serves to accommodate the coil spring 4.

[0018] A single, elongated metal valve stem 3 is positioned along its axis L and passes through the valve chamber VC, the valve stem insertion hole 28, the annular hole 27, and the return passage 23. At the lower end of the valve stem 3, a conical valve body 3a is formed, which decreases in diameter as it approaches the bottom. As shown in Figure 2, when the valve body 3a is seated on the valve seat 20 of the valve body 2, the flow of refrigerant through the orifice passage 21b is restricted. This state is called the non-communication state. However, even when the valve stem 3 is seated on the valve seat 20, a limited amount of refrigerant may still flow. On the other hand, as shown in Figure 3, when the valve body 3a is separated from the valve seat 20, the flow of refrigerant through the orifice passage 21b increases. This state is called the communication state.

[0019] The valve stem 3 has a circumferential groove 3b within the annular hole 27. A C-shaped plate (referred to as a retaining ring) 41 is fitted into the circumferential groove 3b when viewed in the axial direction L. A coil spring 4, positioned between the retaining ring 41 and the bottom wall of the annular hole 27, biases the valve stem 3 upward via the retaining ring 41.

[0020] (Motor unit configuration) Next, the motor unit 100 will be described with reference to Figures 2 to 4. The motor unit 100 consists of a top-cylindrical can 50 fixed to the valve body 2 via a cylindrical holder 11, a stator 55 fitted onto the can 50, a rotor 57 mounted inside the can 50, a roughly top-cylindrical cover 9 covering the periphery of the stator 55, a gear-type reduction mechanism 6 that reduces and transmits the rotational speed of the rotor 57, and a screw drive member (also called a drive member) 58 that converts the rotational movement of the output gear of the reduction mechanism 6 into linear movement via a screw feed mechanism 54 (Figure 4) and transmits it to the valve shaft 3. The can refers to a cylindrical member (the can 50 has a bottomed cylindrical portion) that is attached to the valve body side of the electric valve so as to be sealed inside. The can 50 houses the rotor 57, the reduction mechanism 6, and the screw feed mechanism 54, etc. More precisely, a portion of the screw feed mechanism 54 is housed in the can 50, and the entire screw feed mechanism 54 is housed in the connecting body of the can 50 and the holder 11.

[0021] The stepping motor 5 is rotatably positioned inside the can 50 and has a rotor 57 to which a rotor support member 56 is fixed to the upper inner side. The stepping motor 5 consists only of the rotor 57 and does not include a stator 55. The stator 55, consisting of a yoke 51, bobbin 52, coil 53, etc., is fitted and fixed to the outside of the can 50 and is covered by a resin cover 9. The cover 9 has a connector portion 9a. The connector portion 9a is formed along the axis of the return flow path 23 and has a terminal T inside which it is connected to a stepping motor drive circuit board (not shown).

[0022] The holder 11 consists of a cylindrical body 11a and a flange portion 11b that extends radially outward from the upper end of the body 11a and is joined to the lower end of the can 50. A male thread 11c is formed on the lower outer circumference of the body 11a. The can 50 is fixed to the valve body 2 via the holder 11 by screwing the male thread 11c into a female thread 2b formed on the inner circumference of the recess 2a of the valve body 2. The space between the body 11a and the recess 2a is sealed by an O-ring OR1.

[0023] A screw bearing member 13 is press-fitted into the upper inner circumference of the holder 11. The screw bearing member 13 has a through hole 13a extending along the axis L and a communication hole 13b extending parallel to the axis L from its lower end and opening on its outer circumference. The communication hole 13b has the function of introducing refrigerant flowing from the return passage 23 through the recess 2a to the lower part of the screw bearing member 13 into the can 50. A thin-walled cylindrical body 66 is fixed to the upper outer circumference of the screw bearing member 13. In addition, a stepped cylindrical output shaft portion 29 is rotatably fitted to the upper part of the through hole 13a of the screw bearing member 13.

[0024] In Figure 4, the reduction mechanism 6 comprises a sun gear 61 integrally formed with the rotor support member 56 on the inner circumference side of the rotor 57, a fixed ring gear 62 fixed to the valve body 2 via a thin-walled cylindrical body 66, a planetary gear 63 positioned between the sun gear 61 and the fixed ring gear 62 and meshing with each of them, a carrier 64 that rotatably supports the planetary gear 63, and a bottomed cylindrical output gear member 65 having teeth on its inner circumference that mesh with the planetary gear 63. These components constitute a unique planetary gear reduction mechanism. The number of teeth on the fixed ring gear 62 is set to be different from the number of teeth on the output gear member 65.

[0025] The shaft member 8 passes through the rotor support member 56 and the sun gear 61, holding them rotatably, and the upper end of the shaft member 8 is supported by a support member 81 located inside the top of the can 50.

[0026] The upper part of the output shaft portion 29 is press-fitted into the central opening at the bottom of the output gear member 65, and the lower end of the shaft member 8 is rotatably fitted into the upper opening of the output shaft portion 29.

[0027] The male threaded portion 58a formed on the lower part of the screw drive member 58 is screwed into the female threaded portion 13c formed on the lower part of the through hole 13a of the screw bearing member 13. The rotational movement of the output gear member 65 (the reduced rotational movement of the rotor 57) is converted into linear movement along the axis L by the screw feed mechanism (conversion mechanism) 54 consisting of the male threaded portion 58a and the female threaded portion 13c.

[0028] A slit 29a is formed at the lower end of the output shaft portion 29, and a blade 58b protruding along the axis L is formed at the upper end of the screw drive member 58, and the slit 29a and the blade 58b are slidably engaged with each other. As a result, the output shaft portion 29 is rotatably connected to the screw drive member 58, and when the output gear member 65 (rotor 57) rotates, the output shaft portion 29 and the screw drive member 58 rotate together, but are able to move linearly relative to each other along the axis L.

[0029] A metal ball 15 is coaxially welded to the lower end of the screw drive member 58. Meanwhile, a circular hole 3c is formed at the upper end of the valve stem 3, and a metal ball seat 16 is press-fitted into the circular hole 3c. The enlarged upper end surface 16a of the ball seat 16 is formed into a spherical curved surface (specifically, a shape combining a cone and a sphere) to slidably hold the ball 15.

[0030] (Assembly of electric valve) The assembly process for the electric valve 1 will now be explained. First, the retaining ring 41 is attached to the valve shaft 3. Also, the rotor assembly is prepared by attaching the rotor 57 and reduction mechanism 6 etc. to the inside of the can 50, and fixing the holder 11 to the lower end of the can 50.

[0031] A coil spring 4 is inserted from above into the annular hole 27 of the machined valve body 2, and then the valve stem 3 is inserted into the valve stem insertion hole 28 from above, passing through the recess 2a and the inside of the coil spring 4. At this time, the upper end of the coil spring 4 abuts against the lower surface of the retaining ring 41.

[0032] Subsequently, O-ring OR1 is placed in the inner circumferential groove of recess 2a, and O-ring OR2 is placed at the open end of recess 2a. The male thread 11c of holder 11 is then screwed into the female thread 2b of recess 2a of valve body 2 to attach the rotor assembly to valve body 2. At this time, O-ring OR1 provides a sealing mechanism between the body 11a of holder 11 and recess 2a. The flange portion 11b prevents O-ring OR2 from falling off. Note that O-ring OR2 may be placed on holder 11 before screwing holder 11 to valve body 2, or it may be inserted from the top of the can after holder 11 has been screwed to valve body 2.

[0033] From this state, the cover 9 is brought closer to the can 50 from above, along with the stator 55, and covers the can 50. The lower end of the cover 9 is positioned on the upper side of the valve body 2, so that the O-ring OR2 is placed between the cover 9 and the holder 11, sealing the two together. A plate-shaped stay 18 is placed between the lower end of the cover 9 and the side of the valve body 2, and the two are fixed together with a screw SC. When the connector portion 9a of the cover 9 is connected to a connector (not shown), the external control device and the circuit board of the electric valve 1 are connected via terminal T so that signals can be transmitted.

[0034] (Operation of the electric valve) When the rotor 57 of the stepping motor 5 is driven to rotate in one direction by supplying a predetermined number of valve closing control signals to the stator 55 from an external control device, the rotational speed is input from the sun gear 61 to the reduction mechanism 6, and the rotational speed reduced by the reduction mechanism 6 is then transmitted to the screw drive member 58 via the output shaft 29. When the screw drive member 58 rotates in one direction, the female screw portion 13c and the male screw portion 58a screw relative to each other, and the screw drive member 58 moves downward in the direction of the axis L according to the rotational speed.

[0035] As the screw drive member 58 rotates and descends with the ball 15, rotational sliding occurs between the ball 15 and the upper end surface 16a of the ball seat 16, biasing the valve shaft 3 downward via the ball seat 16. The valve shaft 3 descends against the biasing force of the coil spring 4, and the valve body 3a seats on the valve seat 20, resulting in a closed valve state. As a result, the refrigerant introduced from the condenser (not shown) into the first flow path 21 cannot enter the valve chamber VC from the orifice passage 21b, interrupting the flow of refrigerant between the first flow path 21 and the second flow path 22.

[0036] On the other hand, by supplying an open valve control signal to the stator 55 from a control device (not shown), the rotor 57 of the stepping motor 5 is driven to rotate in the other direction, causing the screw drive member 58 to move upward in the direction of axis L via the reduction mechanism 6 and the screw feed mechanism 54. As a result, the driving force biasing the valve shaft 3 downward disappears, and the valve shaft 3 rises according to the biasing force of the coil spring 4. When the valve shaft 3 rises, the valve body 3a separates from the valve seat 20 and the valve opens. As a result, refrigerant enters the valve chamber VC from the first passage 21 via the first connecting passage 21a and the orifice passage 21b, and further flows out to the outside of the electric valve 1 via the second connecting passage 22a and the second passage 22. For example, the open valve control signal supplied to the stator 55 is determined in response to a signal from a temperature sensor attached to the outlet piping of the evaporator, thereby controlling the opening and closing valve operation and the amount of refrigerant passing through the orifice passage 21b when the valve is open.

[0037] The refrigerant discharged from the second flow path 22 passes through an evaporator (not shown), enters the return flow path 23 of the electric valve 1 at a relatively low pressure, then flows out of the electric valve 1 and reaches a compressor (not shown), where it is pressurized as needed and supplied to the condenser.

[0038] According to this embodiment, the orifice passage 21b side is at high pressure and the valve chamber VC side is at low pressure, which is a so-called forward flow, so pressure is always acting on the valve body 3a in the opening direction. However, since a reduction mechanism 6 with a high reduction ratio is arranged between the stepping motor 5 and the valve shaft 3, the position of the valve body 3a can be reliably controlled at both the closing and opening states, regardless of the pressure applied to the valve body 3a. However, the electric valve 1 of this embodiment can also be used in the case of so-called reverse flow, where the orifice passage 21b side is at low pressure and the valve chamber VC side is at high pressure, with the valve seat 20 in between. In that case, refrigerant from the condenser is introduced into the second passage 22, and refrigerant flows out from the first passage 21 toward the evaporator.

[0039] Furthermore, the can 50 is positioned on the opposite side of the valve seat 20, with the return passage 23 in between. Low-pressure refrigerant is supplied to the inside of the can 50 from the adjacent return passage 23 via the recess 2a and the communication hole 13b. As a result, the supplied refrigerant is used to lubricate the reduction mechanism 6, the wall thickness of the can 50 can be made relatively thin, the strength of each threaded part can be relatively suppressed, and O-rings OR1 and OR2 with relatively low pressure resistance can be used. These factors contribute to miniaturization, weight reduction, and cost reduction of the electric valve 1.

[0040] Furthermore, according to this embodiment, since the shape of the valve body 2 is almost the same as the shape of the valve body of a conventional expansion valve equipped with a power element, it is possible to replace an existing refrigeration cycle with the electric valve of this embodiment without requiring major design changes.

[0041] (Second embodiment) Figure 5 is a longitudinal cross-sectional view of the electric valve 1A according to the second embodiment in the closed state, and Figure 6 is a longitudinal cross-sectional view of the electric valve 1A in the open state. In this embodiment, the differences from the above-described embodiment are that the configuration of the valve body 2A and the valve shaft 3A has been changed, and the guide member 12A and the self-aligning member 19A have been added. Since the other components are common, the same reference numerals are used and redundant explanations are omitted.

[0042] The valve body 2A differs only in that its annular hole 27A has a lower hole 27Aa and an upper hole 27Ab with a larger diameter than the lower hole 27Aa; all other components are the same, so a redundant explanation will be omitted.

[0043] A coil spring 4 is placed in the lower hole 27Aa, and a self-aligning member 19A is placed in the upper hole 27Ab.

[0044] Figure 7 is a perspective view of the centering member 19A. The centering member 19A can be formed, for example, by press-forming a metal plate. Specifically, a long, narrow plate is rolled into a cylindrical shape, and the ends are overlapped to form a circumferential wall 19Aa. In addition, several places (three in this case) of the circumferential wall 19Aa are cut and raised along the circumferential direction to form rectangular tongue pieces 19Ab, and these are bent radially inward starting from one end connected to the circumferential wall 19Aa. Near the tip of each tongue piece 19Ab, a hemispherical protrusion 19Ac is formed that projects toward the center of the circumferential wall 19Aa. This forms the centering member 19A.

[0045] Since the outer diameter of the free-state peripheral wall 19Aa is larger than the inner diameter of the upper hole 27Ab, when inserted into the upper hole 27Ab, the peripheral wall 19Aa elastically deforms and shrinks in diameter. This elastic force biases the outer circumference of the peripheral wall 19Aa toward the inner circumference of the upper hole 27Ab, and the frictional force generated by this attaches the centering member 19A to the upper hole 27Ab. In addition, to prevent the centering member 19A from coming loose, a crimping or other processing may be added to the upper end of the upper hole 27Ab.

[0046] As shown in Figures 5 and 6, a cylindrical guide member 12A is positioned inside the holder 11. The guide member 12A consists of an upper cylindrical portion 12Aa and a lower cylindrical portion 12Ab, which has a smaller diameter than the upper cylindrical portion 12Aa, connected coaxially. The lower cylindrical portion 12Ab is press-fitted into the bottom wall opening of the recess 2a of the valve body 2A. The guide member 12A also has a cylindrical through hole 12Ac that penetrates vertically.

[0047] The valve stem body 3A consists of a first shaft, the lower shaft 31A, and a second shaft, the upper shaft 32A. The slender, rod-shaped metal lower shaft 31A is positioned along the axis L and passes through the valve chamber VC of the valve body 2A, the valve stem insertion hole 28, and the lower hole portion 27Aa.

[0048] A conical valve body portion 31Aa, which decreases in diameter as it goes downward, is formed at the lower end of the lower shaft 31A, and a circumferential groove 31Ab, which engages with the retaining ring 41, is formed on the outer circumference of the lower shaft 31A. Furthermore, a conical seat 31Ac, which decreases in diameter as it goes downward, is formed at the upper end of the lower shaft 31A.

[0049] The upper shaft 32A is formed by connecting a small-diameter portion 32Aa, which is located within the upper hole 27Ab, and a large-diameter portion 32Ab, which is located within the return channel 23 and recess 2a and has a larger diameter than the small-diameter portion 32Aa. The lower end of the small-diameter portion 32Aa is spherical. The large-diameter portion 32Ab is slidably fitted into the through hole 12Ac of the guide member 12A. A ball seat 16, which has a substantially spherical shape, is press-fitted into the recess 32Ac formed at the upper end of the large-diameter portion 32Ab. The hardness (e.g., Vickers hardness) of the ball 15 and the ball seat 16 is higher than the hardness of the upper shaft 32A and the lower shaft 31A.

[0050] The screw drive member 58 and the upper shaft 32A are connected (contact) along the axis L so as to be able to transmit driving force, with the ball 15 in contact with the ball seat 16. Also, the upper shaft 32A and the lower shaft 31A are connected (contact) along the axis L so as to be able to transmit driving force, with the lower end of the small diameter portion 32Aa in contact with the conical seat 31Ac. By bringing the hemispherical lower end of the small diameter portion 32Aa into contact with the conical seat 31Ac, coaxiality between the upper shaft 32A and the lower shaft 31A can be ensured.

[0051] The contact surface diameter A between the ball seat 16 and the ball 15 is smaller than the contact surface diameter B between the lower end of the small diameter portion 32Aa and the conical seat 31Ac (A <B)。

[0052] In the assembly process of the electric valve 1A, first, the retaining ring 41 is attached to the lower shaft 31A, and, similar to the embodiment described above, a rotor assembly is prepared in which the rotor 57 and reduction mechanism 6 are assembled inside the can 50, and the holder 11 is fixed to the lower end of the can 50.

[0053] A coil spring 4 is inserted from above into the lower hole 27Aa of the machined valve body 2A, and then the lower shaft 31A is inserted into the valve shaft insertion hole 28 from above, passing through the recess 2a and the inside of the coil spring 4. At this time, the upper end of the coil spring 4 abuts against the lower surface of the retaining ring 41.

[0054] Subsequently, the centering member 19A is inserted into the upper hole 27Ab, and the guide member 12A is press-fitted into the bottom wall opening of the recess 2a to complete the assembly. Furthermore, the upper shaft 32A is brought closer from above the guide member 12A, passing through the through hole 12Ac, and the small diameter portion 32Aa is inserted into the centering member 19A, with its lower end contacting the conical seat 31Ac of the lower shaft 31A. At this time, the three tongues 19Ab of the centering member 19A elastically deform, and the convex portion 19Ac contacts the outer circumference of the small diameter portion 32Aa, exhibiting a so-called centering function so that the small diameter portion 32Aa does not shift relative to the axis L.

[0055] Subsequently, the motorized valve 1A is completed by assembling the rotor assembly, similar to the first embodiment. Alternatively, a self-aligning member 19A may be provided in the first embodiment to align the valve shaft.

[0056] (Operation of the electric valve) When the rotor 57 of the stepping motor 5 is driven to rotate in one direction by supplying a predetermined number of valve closing control signals to the stator 55 from an external control device, the rotational speed reduced by the reduction mechanism 6 is transmitted to the screw drive member 58 via the output shaft 29, causing the screw drive member 58 to move downward in the direction of axis L.

[0057] The screw drive member 58 rotates downward together with the ball 15, and the downward driving force is transmitted to the lower shaft 31A via the upper shaft 32A, causing the valve body 31Aa to seat on the valve seat 20 and the valve to close. At this time, the contact surface diameter A between the ball seat 16 and the ball 15 is smaller than the contact surface diameter B between the lower end of the small diameter portion 32Aa and the conical seat 31Ac. Therefore, relative rotation mainly occurs between the ball seat 16 and the ball 15, and relative rotation between the upper shaft 32A and the lower shaft 31A is unlikely to occur. As a result, eccentricity (misalignment) with respect to the axis L due to the runout of the lower shaft 31A can be suppressed, thereby improving the contact between the valve body 31Aa and the valve seat 20. In addition, since the ball seat 16 and the ball 15 are made of a relatively hard material, wear can be suppressed even if relative sliding occurs.

[0058] On the other hand, when the rotor 57 of the stepping motor 5 is rotated in the opposite direction by supplying an opening control signal to the stator 55 from a control device (not shown), the screw drive member 58 moves upward in the direction of axis L via the reduction mechanism 6 and the screw feed mechanism 54. As a result, the driving force biasing the upper shaft 32A downward disappears, so the lower shaft 31A rises according to the biasing force of the coil spring 4, and the valve body 31Aa separates from the valve seat 20 and the valve opens.

[0059] (modified version) Figure 8 is a longitudinal cross-sectional view of the modified holder 11B, and Figure 9 is a top view of the holder 11B. The holder 11B of this modified version can be used in place of the holder 11 and guide member 12A of the second embodiment.

[0060] The limiting member, holder 11B, is comprised of a cylindrical body 11Ba, a flange portion 11Bb extending radially outward from the upper end of the body 11Ba and joined to the can 50, and a bottom wall 11Bd extending radially inward from the upper end of the body 11Ba. A male thread 11Bc is formed on the lower outer circumference of the body 11Ba, and an opening 11Be is formed in the center of the bottom wall 11Bd. In this modified example, holder 11B is also fixed to the valve body 2 by screwing the male thread 11Bc into a female thread 2b formed on the inner circumference of a recess 2a formed at the upper end of the valve body 2 as shown in Figures 5 and 6.

[0061] The inner circumference of the opening 11Be has a shape such that a portion along the circumferential direction of the cylindrical surface is connected by a single plane parallel to the axis L in a short-circuit manner; that is, the opening 11Be has a D-shape (non-cylindrical shape) when viewed in the direction of the axis L. The outer circumference of the large-diameter portion 32Ab of the upper shaft 32A used in this modified example is also not a perfect cylindrical shape, but has a D-shape (corresponding non-cylindrical shape) when viewed in the direction of the axis L, corresponding to the opening 11Be. The non-cylindrical shape is not limited to the above, and for example, a shape such that a portion along the circumferential direction of the cylindrical surface is connected by two planes parallel to the axis L in a short-circuit manner may also be used. Here, the holder 11B and the upper shaft 32A constitute a rotation limiting mechanism.

[0062] When the upper shaft 32A is inserted into the opening 11Be of the holder 11B, the upper shaft 32A is guided by the opening 11Be and displaced along the axis L, but it is unable to rotate around the axis L. Therefore, even if the screw drive member 58 rotates, the rotation of the upper shaft 32A can be prevented (restricted), thereby preventing misalignment of the upper shaft 32A and also suppressing misalignment of the lower shaft 31A.

[0063] Furthermore, the through-hole 12Ac of the guide member 12A in the second embodiment may be made into a similar non-cylindrical shape, thereby allowing the guide member 12A to be used as a limiting member. In this case, the large-diameter portion 32Ab of the upper shaft 32A may be made into a similar non-cylindrical shape, thereby enabling the same rotation limiting mechanism to be constructed, and thereby suppressing misalignment of the upper shaft 32A during valve operation. A rotation limiting mechanism consisting of a guide member and holder into which a non-cylindrical valve shaft is fitted can also be used in the first embodiment.

[0064] (Third embodiment) Figure 10 is a longitudinal cross-sectional view of the electric valve 1C according to the third embodiment in the closed state. In this embodiment, the differences from the first embodiment are that the configuration of the valve body 2C, valve shaft 3C, and holder 11C has been changed, and a self-aligning member 19A has been added. Other components are common, so the same reference numerals are used and redundant explanations are omitted.

[0065] The valve body 2C differs only in that the annular hole 27C is shortened in the axial direction and a self-aligning member 19A is placed inside it instead of the coil spring 4. All other configurations are the same as in the first embodiment, so a redundant explanation is omitted. The self-aligning member 19A is the same as the one used in the second embodiment.

[0066] The valve stem body 3C differs only in that the circumferential groove 3Cb is shifted above the return flow path 23; all other configurations are the same as in the first embodiment, so a redundant explanation will be omitted.

[0067] The holder 11C comprises a cylindrical body 11Ca, a flange portion 11Cb extending radially outward from the upper end of the body 11Ca and joined to the lower end of the can 50, and a bottomed cylindrical holding portion 11Cd joined to the lower end of the body 11Ca. A male thread 11Cc is formed on the lower outer circumference of the body 11Ca. The configuration of the holder 11C other than the holding portion 11Cd is the same as in the first embodiment, so a redundant explanation is omitted.

[0068] The bottom wall of the retaining portion 11Cd has a through hole 11Ce in its center into which the valve stem 3C is slidably fitted. A retaining ring 41 engages with a circumferential groove 3Cb of the valve stem 3C formed radially inward of the main body portion 11Ca. A coil spring (also called simply a spring) 4 is positioned in a compressed state around the valve stem 3C and between the retaining ring 41 and the bottom wall of the retaining portion 11Cd, thereby biasing the valve stem 3C in the valve closing direction.

[0069] In this embodiment, the electric valve 1C has a configuration in which, instead of forming a coil spring 4 housing portion in the valve body 2C, a holding portion 11Cd is provided as a coil spring 4 housing portion in a part of the holder 11C. With this configuration, the valve shaft 3C, valve body 2C, and motor unit 100 (excluding the stator unit) can be treated as a single module. Therefore, the single module can be pre-assembled and attached to the valve body 2C in one step, improving ease of assembly.

[0070] It should be noted that the present invention is not limited to the embodiments described above. Within the scope of the present invention, any component of the embodiments described above can be modified. Furthermore, any component can be added or omitted in the embodiments described above. For example, although an example using a planetary gear mechanism as a reduction mechanism has been shown, it is not limited to this and a gear pair can also be used. Also, in this embodiment, the axis of the valve stem intersects with the axis of the return flow path, but the axis of the valve stem does not have to intersect with the axis of the return flow path, nor does the valve stem have to intersect with the return flow path itself.

[0071] This specification includes disclosures of the following inventions. (First aspect) A valve body comprising a first passage through which refrigerant is introduced, a second passage for discharging refrigerant, a third passage for passing refrigerant, and a valve seat formed between the first and second passages, A valve stem body having a valve body portion that can seat on the valve seat, A motor is provided on the valve body on the opposite side of the third flow path from the valve seat, The motor has a conversion mechanism that converts the rotation of the rotor into linear motion and transmits it to the valve shaft body. An electric valve characterized by the following features.

[0072] (Second aspect) The motor comprises a rotor, a reduction mechanism for reducing the rotation of the motor rotor, a conversion mechanism for converting the rotation reduced by the reduction mechanism into linear motion, and a can housing at least the reduction mechanism. The inside of the can is in communication with the third flow path. An electric valve according to a first embodiment, characterized by the following:

[0073] (Third aspect) Between the conversion mechanism and the valve stem body, a drive member that rotates and is displaced in the axial direction, and a ball seat fixed to the valve stem body and having a spherical end are arranged. The ball fixed to the drive member contacts the end of the ball seat, thereby transmitting the axial displacement of the drive member to the valve shaft. An electric valve according to the first or second embodiment, characterized by the above.

[0074] (Fourth aspect) The valve body has a rotation limiting mechanism that restricts the rotation of the valve shaft. A third embodiment of an electric valve characterized by the following:

[0075] (Fifth aspect) The rotation limiting mechanism comprises a limiting member fixed to the valve body and having a non-cylindrical opening, and a non-cylindrical valve shaft that engages with the opening. A fourth embodiment of an electric valve characterized by the following:

[0076] (Sixth aspect) The valve shaft comprises a first shaft having the valve body portion seated on the valve seat, and a second shaft connected to the first shaft and having the ball seat. The hardness of the material of the ball seat is higher than the hardness of the materials of the first shaft and the second shaft. An electric valve according to any of the first to fifth embodiments, characterized by the above.

[0077] (Seventh aspect) The end of the first shaft has a conical shape, and the end of the second shaft has a spherical shape, with the conical end and the spherical end in contact with each other. The contact surface diameter between the ball and the ball seat is smaller than the contact surface diameter between the conical end and the spherical end. A sixth embodiment of an electric valve characterized by the following:

[0078] (Eighth aspect) The valve shaft body consists of a single rod-shaped member, The valve body has a self-aligning member that is attached to the valve body and contacts the outer circumference of the valve shaft at multiple points along the circumferential direction to apply elastic force, An electric valve according to any of the first to fifth embodiments, characterized by the above.

[0079] (Ninth aspect) A cylindrical holder is provided to fix the screw bearing member, which has an internal thread and constitutes the conversion mechanism, to the valve body. The holder has a holding portion that holds a spring that biases the valve stem body in the closing direction. An electric valve according to any of the first to eighth embodiments, characterized by the above.

[0080] (Tenth aspect) The aforementioned electric valve is used in a refrigeration cycle. Coolant from the condenser is introduced into the first flow path, coolant flows out from the second flow path toward the evaporator, and coolant from the evaporator passes through the third flow path. An electric valve according to any of the first to ninth embodiments, characterized by the above. [Explanation of symbols]

[0081] 1, 1A: Electric valve 2, 2A: Valve body 3, 3A: Valve stem body 3a, 31Aa: Valve body 4: Coil spring 5: Stepping motor 6: Reduction mechanism 20: Alveolar seat 21: First channel 22: Second channel 23: Return channel (third channel) 27: Annular hole 31A: Lower axis 32A: Upper axis 50: Can 55: Status 57: Rotor 100: Motor Unit VC: Valve chamber

Claims

1. A valve body comprising a first passage through which refrigerant is introduced, a second passage for discharging refrigerant, a third passage for passing refrigerant, and a valve seat formed between the first and second passages, A valve stem body having a valve body portion that can seat on the valve seat, A motor is provided on the valve body on the opposite side of the third flow path from the valve seat, The motor has a conversion mechanism that converts the rotation of the rotor into linear motion and transmits it to the valve shaft body, The motor comprises a rotor, a reduction mechanism for reducing the rotation of the motor rotor, a conversion mechanism for converting the rotation reduced by the reduction mechanism into linear motion, and a can housing at least the reduction mechanism. The inside of the can is in communication with the third flow path, Between the conversion mechanism and the valve stem body, a drive member that rotates and is displaced in the axial direction, and a ball seat fixed to the valve stem body and having a spherical end are arranged. The ball fixed to the drive member contacts the end of the ball seat, thereby transmitting the axial displacement of the drive member to the valve shaft. The valve shaft comprises a first shaft having the valve body portion seated on the valve seat, and a second shaft connected to the first shaft and having the ball seat. The axis of the second axis is tiltable with respect to the axis of the first axis. An electric valve characterized by the following features.

2. The hardness of the material of the ball seat is higher than the hardness of the material of the first shaft and the second shaft. The electric valve according to feature 1.

3. The end of the first shaft has a conical shape, and the end of the second shaft has a spherical shape, with the conical end and the spherical end in contact with each other. The contact surface diameter between the ball and the ball seat is smaller than the contact surface diameter between the conical end and the spherical end. The electric valve according to feature 1.

4. A guide member having a through hole into which the second shaft is slidably fitted is attached to the valve body. The electric valve according to feature 1.

5. The valve body is fitted with a self-aligning member that contacts the outer circumference of the first shaft to perform a self-aligning function for the first shaft, The electric valve according to feature 1.

6. The aforementioned electric valve is used in a refrigeration cycle, in which refrigerant from the condenser is introduced into the first flow path, refrigerant flows out from the second flow path toward the evaporator, and refrigerant from the evaporator passes through the third flow path. The electric valve according to feature 1.

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