Electric valve

Abstract

Provided is an electric valve that can be made compact and lightweight while improving the degree of freedom of opening / closing valve control.　This electric valve includes: a valve main body comprising a first flow passage into which a refrigerant is introduced, a second flow passage from which the refrigerant flows out, a third flow passage through which the refrigerant passes, and a valve seat formed between the first flow passage and the second flow passage; a valve shaft body comprising a valve body part that can be seated on the valve seat; a motor disposed in the valve body and positioned on the opposite side of the third flow passage to the valve seat; and a conversion mechanism that converts the rotation of a rotor of the motor into linear motion and transmits the linear motion to the valve shaft body.

Description

Motor-operated valve

[0001] The present invention relates to a motor-operated valve.

[0002] For example, in the refrigeration cycle of an air conditioner installed in an automobile, a temperature-sensitive thermal expansion valve is used to adjust the amount of refrigerant passing through according to the temperature. Conventionally, such a thermal expansion valve employs a power element that drives the valve element using the pressure of the enclosed working gas.

[0003] Generally, power elements are useful because they have a simple mechanical structure and can sense the refrigerant temperature to control the opening and closing of the expansion valve, but in recent refrigeration cycles, there is a demand for more flexible opening and closing valve control, and for example, there are cases where forced valve closing operation is required regardless of the refrigerant temperature.Therefore, a configuration has already been put into practical use in which a solenoid valve and an expansion valve are arranged in series in the refrigeration cycle and the solenoid valve shuts off the flow of refrigerant passing through the expansion valve, but the use of two valve devices leads to an increase in the size of the structure.

[0004] In response to this, Patent Document 1 discloses an electrically operated valve that is combined with a valve unit and a passage body and that can open and close the valve using a stepping motor in the valve unit. This electrically operated valve can be used as an expansion valve in a refrigeration cycle, and by communicating with an external device, the stepping motor can be operated to move the valve element toward or away from the valve seat in the passage body regardless of the temperature of the refrigerant.

[0005] JP 2023-53708 A

[0006] However, in the motor-operated valve of Patent Document 1, the valve unit is disposed adjacent to a flow path provided in the passage body through which high-pressure refrigerant flows. In this structure, the introduction of high-pressure refrigerant increases the internal pressure of the can that covers the rotor, etc., so it is necessary to increase the strength of the can and fastening members and the pressure resistance of the seals, etc., which results in an increase in the size and weight of the structure.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electrically operated valve that can improve the degree of freedom in controlling the opening and closing of the valve while ensuring a small size and light weight.

[0008] In order to achieve the above object, the motor-operated valve according to the present invention is characterized by comprising: a valve body having a first flow path through which a refrigerant is introduced, a second flow path through which the refrigerant flows out, 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 having a valve body portion that can be seated on the valve seat; a motor disposed in the valve body on the opposite side of the third flow path from the valve seat; and a conversion mechanism that converts the rotation of the rotor of the motor into linear movement and transmits it to the valve stem.

[0009] The present invention can provide a motor-operated valve that can improve the degree of freedom in controlling the opening and closing of the valve while ensuring a small size and light weight.

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

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

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

[0013] (First embodiment) Fig. 1 is a side view of the motor-operated valve 1 in this embodiment as seen from the first flow path 21 side. Fig. 2 is a vertical cross-sectional view of the motor-operated valve 1 in a valve-closed state, and Fig. 3 is a vertical cross-sectional view of the motor-operated valve 1 in an open state. Fig. 4 is a cross-sectional view showing the periphery of the motor unit 100.

[0014] 2 and 3, the motor-operated valve 1 includes a valve body 2, a valve stem 3, and a motor unit 100.

[0015] The valve body 2 includes a first flow path 21, a second flow path 22, a first connection path 21a, an orifice path 21b, a second connection path 22a, and a return flow path (third flow path) 23. The first flow path 21 and the first connection path 21a each extend perpendicular to the axis L, and the inner diameter of the first flow path 21 is larger than the inner diameter of the first connection path 21a. The second flow path 22 and the second connection path 22a extend perpendicular to the axis L on the opposite side of the valve body 2 from the first flow path 21, and the inner diameter of the second flow path 22 is larger than the inner diameter of the second connection path 22a. The orifice path 21b extends along the axis L, and its lower end communicates with the first connection path 21a near the tip, and its upper end communicates with the second connection path 22a near the tip. The second connecting passage 22a defines a valve chamber VC, and the upper end of the orifice passage 21b defines a 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 communicating with the return passage 23 is formed at the upper end of the valve body 2.

[0016] The first flow path 21 is a supply-side flow path connected to a 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 fluid in the valve chamber VC is discharged via the discharge-side flow path to an evaporator (not shown) outside the motor-operated valve. The return flow path 23 receives refrigerant that has passed through the evaporator.

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

[0018] The metal valve stem 3, which is a single, elongated rod, is disposed along the axis L and passes through the valve chamber VC, the valve stem insertion hole 28, the annular hole 27, and the return flow path 23. The lower end of the valve stem 3 is formed with a conical valve element 3a whose diameter decreases downward. As shown in FIG. 2 , when the valve element 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 a non-communicating 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, when the valve element 3a is separated from the valve seat 20 as shown in FIG. 3 , the flow of refrigerant through the orifice passage 21b increases. This state is called a communicating 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 direction of the axis L. A coil spring 4 is arranged between the retaining ring 41 and the bottom wall of the annular hole 27 and biases the valve stem 3 upward via the retaining ring 41.

[0020] (Configuration of the Motor Unit) Next, the motor unit 100 will be described with reference to FIGS. 2 to 4. The motor unit 100 comprises a cylindrical can 50 with a top that is 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 generally cylindrical cover 9 with a top that surrounds the stator 55, a gear-type reduction mechanism 6 that reduces the rotational speed of the rotor 57 before transmitting it, and a screw drive member (also referred to as 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 (FIG. 4) and transmits it to the valve stem 3. The can 50 is a member with a cylindrical portion (the can 50 has a cylindrical portion with a bottom) that is attached to the valve body side of the electrically operated valve so that its interior is sealed. The can 50 houses the rotor 57, the reduction mechanism 6, the screw feed mechanism 54, etc. More precisely, a part of the screw feed mechanism 54 is housed in the can 50 , and the entire screw feed mechanism 54 is housed in the connection between the can 50 and the holder 11 .

[0021] The stepping motor 5 is disposed inside the can 50 and is rotatable relative to the can 50, and has a rotor 57 with a rotor support member 56 fixed to the upper inside of the rotor 57. The stepping motor 5 consists only of the rotor 57 and does not include a stator 55. The stator 55, which is composed of a yoke 51, a bobbin 52, a 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 a terminal T connected to a stepping motor drive circuit board (not shown) is disposed inside the connector portion 9a.

[0022] The holder 11 comprises a cylindrical main body 11a and a flange portion 11b that extends radially outward from the upper end of the main body 11a and is joined to the lower end of the can 50. A male thread 11c is formed on the outer periphery of the lower part of the main body 11a. The can 50 is fixed to the valve main body 2 via the holder 11 by threading the male thread 11c into a female thread 2b that is formed on the inner periphery of a recess 2a in the valve main body 2. An O-ring OR1 seals the gap between the main body 11a and the recess 2a.

[0023] The threaded bearing member 13 is press-fitted onto the upper inner periphery of the holder 11. The threaded bearing member 13 has a through hole 13a extending along the axis L and a communication hole 13b extending from the lower end of the through hole 13a parallel to the axis L and opening at the outer periphery. The communication hole 13b serves to introduce refrigerant flowing from the return flow path 23 through the recess 2a below the threaded bearing member 13 into the can 50. A thin-walled cylindrical body 66 is fixed to the outer periphery of the upper end of the threaded bearing member 13. A stepped cylindrical output shaft 29 is rotatably fitted into the upper part of the through hole 13a of the threaded bearing member 13.

[0024] 4, the reduction mechanism 6 comprises a sun gear 61 formed integrally with the rotor support member 56 on the inner peripheral side of the rotor 57, a fixed ring gear 62 fixed to the valve body 2 via a thin-walled cylindrical body 66, planetary gears 63 arranged between the sun gear 61 and the fixed ring gear 62 and meshing with them, a carrier 64 that rotatably supports the planetary gears 63, and a cylindrical output gear member 65 with a bottom and teeth on its inner periphery that mesh with the planetary gears 63, which together form a paradox planetary gear reduction mechanism. The number of teeth of the fixed ring gear 62 is set to be different from the number of teeth of the output gear member 65.

[0025] The shaft member 8 passes through the rotor support member 56 and the sun gear 61 and holds them rotatably, and the upper end of the shaft member 8 is supported by a support member 81 arranged 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 this output shaft portion 29.

[0027] A male threaded portion 58a formed on the lower portion of a screw drive member 58 is threadedly engaged with a female threaded portion 13c formed on the lower portion 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 a 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 29, and a blade 58b protruding along the axis L is formed at the upper end of the screw drive member 58, with the slit 29a and the blade 58b slidably engaging with each other. As a result, the output shaft 29 is connected to the screw drive member 58 so as to be rotatable together, and when the output gear member 65 (rotor 57) rotates, the output shaft 29 and the screw drive member 58 rotate together, but are also capable of linear movement 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 in 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) and slidably holds the ball 15.

[0030] (Assembly of the Motor-Operated Valve) The assembly process of the motor-operated valve 1 will be described. First, the retaining ring 41 is attached to the valve stem 3. Then, the rotor 57, the reduction mechanism 6, etc. are attached to the inside of the can 50, and the holder 11 is fixed to the lower end of the can 50 to prepare a rotor assembly.

[0031] The 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 from above through the recess 2a and the inside of the coil spring 4 into the valve stem insertion hole 28. At this time, the upper end of the coil spring 4 abuts against the underside of the retaining ring 41.

[0032] Thereafter, an O-ring OR1 is placed in the inner circumferential groove of the recess 2a, an O-ring OR2 is placed at the open end of the recess 2a, and the male thread 11c of the holder 11 is threadedly engaged with the female thread 2b of the recess 2a of the valve body 2, thereby attaching the rotor assembly to the valve body 2. At this time, the O-ring OR1 provides a sealing mechanism between the body 11a of the holder 11 and the recess 2a. The flange portion 11b prevents the O-ring OR2 from falling off. The O-ring OR2 may be placed in the holder 11 before the holder 11 is threaded onto the valve body 2, or it may be inserted from the top of the can after the holder 11 is threaded onto the valve body 2 and assembled.

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

[0034] (Operation of the Motor-Operated Valve) When the rotor 57 of the stepping motor 5 is driven to rotate in one direction by supplying a valve-closing control signal with a predetermined number of pulses 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 transmitted to the screw drive member 58 via the output shaft 29. When the screw drive member 58 rotates in one direction, the female thread portion 13c and the male thread portion 58a threadably rotate 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 together with the ball 15, a rotational slide occurs between the ball 15 and the upper end surface 16a of the ball seat 16, and the valve stem 3 is urged downward via the ball seat 16. The valve stem 3 descends against the urging force of the coil spring 4, and the valve body portion 3a seats on the valve seat 20, resulting in a closed valve state. As a result, the refrigerant introduced into the first flow path 21 from a condenser (not shown) cannot enter the valve chest VC through the orifice passage 21b, and the flow of refrigerant is interrupted between the first flow path 21 and the second flow path 22.

[0036] On the other hand, when a control device (not shown) supplies a valve-opening control signal to the stator 55 to rotate the rotor 57 of the stepping motor 5 in the other direction, the screw drive member 58 moves upward in the direction of the axis L via the reduction gear mechanism 6 and the screw feed mechanism 54. As a result, the driving force biasing the valve stem 3 downward disappears, and the valve stem 3 rises in response to the biasing force of the coil spring 4. When the valve stem 3 rises, the valve body portion 3a separates from the valve seat 20, establishing an open valve state. As a result, refrigerant flows from the first flow path 21 into the valve chamber VC via the first connecting path 21a and the orifice path 21b, and then flows out of the motor-operated valve 1 via the second connecting path 22a and the second flow path 22. For example, the valve-opening 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 of the valve and the amount of refrigerant passing through the orifice path 21b when the valve is open.

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

[0038] According to this embodiment, the valve seat 20 is sandwiched between the orifice passage 21b and the valve chamber VC, resulting in a so-called forward flow, whereby pressure always acts on the valve element 3a in the valve-opening direction. However, because the speed reduction mechanism 6 with a high reduction ratio is disposed between the stepping motor 5 and the valve stem 3, the position of the valve element 3a can be reliably controlled both when the valve is closed and when the valve is open, regardless of the pressure applied to the valve element 3a. However, the motor-operated valve 1 of this embodiment can also be used in a so-called reverse flow, whereby pressure is low on the orifice passage 21b and high on the valve chamber VC, whereby refrigerant from the condenser is introduced into the second flow path 22, and refrigerant flows out of the first flow path 21 toward the evaporator.

[0039] The can 50 is disposed on the opposite side of the return flow path 23 from the valve seat 20, and low-pressure refrigerant is supplied to the interior of the can 50 from the adjacent return flow path 23 via the recess 2a and the communication hole 13b. Therefore, while the supplied refrigerant is used to lubricate the reduction gear mechanism 6, the thickness of the can 50 can be made relatively thin, the strength of each threaded portion can be relatively reduced, and O-rings OR1 and OR2 with relatively low pressure resistance can be used, which contribute to the miniaturization, weight reduction, cost reduction, etc. of the motor-operated valve 1.

[0040] Furthermore, according to this embodiment, 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, so that it is possible to replace the electric valve of this embodiment in refrigeration cycles that are already in use without requiring major design changes.

[0041] Second Embodiment Fig. 5 is a longitudinal cross-sectional view of a motor-operated valve 1A according to a second embodiment in a valve-closed state, and Fig. 6 is a longitudinal cross-sectional view of the motor-operated valve 1A in an open state. This embodiment differs from the above-described embodiment in that the configurations of the valve body 2A and the valve stem 3A are changed and a guide member 12A and an aligning member 19A are added. Since the other configurations are the same, the same reference numerals are used and redundant explanations will be omitted.

[0042] The valve body 2A differs only in that the annular hole portion 27A has a lower hole portion 27Aa and an upper hole portion 27Ab having a larger diameter than the lower hole portion 27Aa. Since the other configurations are the same, a redundant description will be omitted.

[0043] A coil spring 4 is disposed in the lower hole portion 27Aa, and an aligning member 19A is disposed in the upper hole portion 27Ab.

[0044] FIG. 7 is a perspective view of the aligning member 19A. The aligning member 19A can be formed, for example, by press-forming a metal plate. Specifically, a long, thin plate is rolled into a cylindrical shape, and the two ends are overlapped to form the peripheral wall 19Aa. The peripheral wall 19Aa is then cut and raised at multiple locations (three locations in this example) along the circumferential direction to form rectangular tongues 19Ab, which are then bent radially inward from one end connected to the peripheral wall 19Aa. Near the tip of each tongue 19Ab, a hemispherical protrusion 19Ac is formed, protruding toward the center of the peripheral wall 19Aa. This completes the aligning member 19A.

[0045] Because the outer diameter of peripheral wall 19Aa in its free state is larger than the inner diameter of upper hole 27Ab, peripheral wall 19Aa elastically deforms and contracts in diameter when inserted into upper hole 27Ab, and this elastic force urges the outer periphery of peripheral wall 19Aa toward the inner periphery of upper hole 27Ab, generating frictional force that attaches aligning member 19A to upper hole 27Ab. Note that, to prevent aligning member 19A from slipping out, additional processing such as caulking may be performed on the upper end of upper hole 27Ab.

[0046] 5 and 6, a cylindrical guide member 12A is disposed inside the holder 11. The guide member 12A comprises an upper cylindrical portion 12Aa and a lower cylindrical portion 12Ab, which is coaxially connected to each other and has a smaller diameter than the upper cylindrical portion 12Aa. The lower cylindrical portion 12Ab is press-fit 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 passes through it vertically.

[0047] The valve stem 3A is composed of a lower stem 31A, which is a first stem, and an upper stem 32A, which is a second stem. The elongated, rod-shaped lower stem 31A, which is made of metal, is disposed 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 is formed at the lower end of the lower shaft 31A, the diameter of which decreases as it extends downward. A circumferential groove 31Ab is formed on the outer periphery of the lower shaft 31A, into which a retaining ring 41 engages. Furthermore, a conical seat 31Ac is formed at the upper end of the lower shaft 31A, the diameter of which decreases as it extends downward.

[0049] The upper shaft 32A is composed of a small-diameter portion 32Aa disposed within the upper hole portion 27Ab and a large-diameter portion 32Ab disposed within the return flow path 23 and the recess 2a and having 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 slidably fits into the through-hole 12Ac of the guide member 12A. A substantially spherical ball seat 16 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] With ball 15 abutting against ball seat 16, screw drive member 58 and upper shaft 32A are coupled (abutted) together along axis L so as to transmit a driving force. With the lower end of small diameter portion 32Aa abutting against conical seat 31Ac, upper shaft 32A and lower shaft 31A are coupled (abutted) together along axis L so as to transmit a driving force. By abutting the hemispherical lower end of small diameter portion 32Aa against conical seat 31Ac, coaxiality between upper shaft 32A and lower shaft 31A can be ensured.

[0051] A contact surface diameter A between the ball seat 16 and the ball 15 is smaller than a 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, a retaining ring 41 is attached to the lower shaft 31A, and then, as in the above-described embodiment, a rotor assembly is prepared in which the rotor 57, reduction mechanism 6, etc. are attached inside the can 50 and the holder 11 is fixed to the lower end of the can 50.

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

[0054] Thereafter, the aligning member 19A is inserted into the upper hole portion 27Ab, and the guide member 12A is press-fitted into the bottom wall opening of the recess 2a to assemble it. Furthermore, the upper shaft 32A is brought closer from above the guide member 12A, passing through the through hole 12Ac and inserting the small-diameter portion 32Aa into the aligning member 19A until its lower end abuts against the conical seat 31Ac of the lower shaft 31A. At this time, the three tongues 19Ab of the aligning member 19A elastically deform, causing the convex portions 19Ac to abut against the outer periphery of the small-diameter portion 32Aa, thereby providing a so-called aligning function that prevents the small-diameter portion 32Aa from shifting relative to the axis L.

[0055] Thereafter, the rotor assembly is attached to complete the motor-operated valve 1A, as in the first embodiment. Note that an aligning member 19A may be provided in the first embodiment to align the valve stem.

[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 valve closing control signal with a predetermined number of pulses from an external control device to the stator 55, the rotational speed reduced by the reduction mechanism 6 is transmitted to the screw drive member 58 via the output shaft portion 29, and the screw drive member 58 moves downward in the direction of the axis L.

[0057] The screw drive member 58 rotates and descends 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 element 31Aa to seat on the valve seat 20 and enter a closed state. 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. This means that relative rotation occurs primarily between the ball seat 16 and the ball 15, and not between the upper shaft 32A and the lower shaft 31A. This reduces eccentricity (misalignment) with respect to the axis L due to whirling of the lower shaft 31A, thereby improving the contact between the valve element 31Aa and the valve seat 20. Furthermore, because the ball seat 16 and the ball 15 are made of a relatively hard material, wear is reduced even when they slide relative to each other.

[0058] On the other hand, when a valve-opening control signal is supplied to the stator 55 from a control device (not shown) to rotate the rotor 57 of the stepping motor 5 in the other direction, the screw drive member 58 moves upward in the direction of the axis L via the speed reduction mechanism 6 and the screw feed mechanism 54. As a result, the driving force urging the upper shaft 32A downward disappears, and the lower shaft 31A rises in accordance with the urging force of the coil spring 4, and the valve body portion 31Aa separates from the valve seat 20, establishing an open valve state.

[0059] (Modification) Fig. 8 is a vertical cross-sectional view of a holder 11B according to a modification, and Fig. 9 is a top view of the holder 11B. The holder 11B of this modification can be used in place of the holder 11 and the guide member 12A of the second embodiment.

[0060] The holder 11B, which serves as a limiting member, comprises a cylindrical main body 11Ba, a flange 11Bb extending radially outward from the upper end of the main body 11Ba and joined to the can 50, and a bottom wall 11Bd extending radially inward from the upper end of the main body 11Ba. A male thread 11Bc is formed on the outer periphery of the lower part of the main body 11Ba, and an opening 11Be is formed in the center of the bottom wall 11Bd. The holder 11B of this modification is also fixed to the valve main body 2 by threading the male thread 11Bc into a female thread 2b formed on the inner periphery of a recess 2a formed at the upper end of the valve main body 2 shown in FIGS. 5 and 6.

[0061] The inner periphery of opening 11Be has a shape in which a portion of the cylindrical surface along the circumferential direction is connected in a short-circuited manner by one plane parallel to axis L, i.e., opening 11Be has a D-shape (non-cylindrical shape) when viewed in the direction of axis L. The outer periphery of large diameter portion 32Ab of upper shaft 32A used in this modified example is also not completely cylindrical, but has a D-shape (corresponding non-cylindrical shape) when viewed in the direction of axis L corresponding to opening 11Be. The non-cylindrical shape is not limited to the above, and may be, for example, a shape in which a portion of the cylindrical surface along the circumferential direction is connected in a short-circuited manner by two planes parallel to axis L. Here, holder 11B and 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 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 (limited), thereby preventing misalignment of the upper shaft 32A and also suppressing misalignment of the lower shaft 31A.

[0063] In addition, by making the through hole 12Ac of the guide member 12A in the second embodiment a similar non-cylindrical shape, the guide member 12A may be used as a limiting member. In such a case, by making the large diameter portion 32Ab of the upper shaft 32A a similar non-cylindrical shape, a rotation limiting mechanism can be similarly configured, thereby suppressing misalignment of the upper shaft 32A during the opening and closing valve operation. Such a rotation limiting mechanism consisting of a guide member and a holder into which a non-cylindrical valve stem is fitted can also be used in the first embodiment.

[0064] 10 is a longitudinal cross-sectional view of a motor-operated valve 1C according to a third embodiment in a closed state. This embodiment differs from the first embodiment in that the configurations of a valve body 2C, a valve stem 3C, and a holder 11C are changed, and an aligning member 19A is added. Since the other configurations are the same as those of the first embodiment, the same reference numerals are used and redundant description will be omitted.

[0065] The valve body 2C is different from the first embodiment only in that the annular hole 27C is shortened in the axial direction and an aligning member 19A is disposed therein instead of the coil spring 4. The other configuration is the same as that of the first embodiment, and therefore a duplicated description will be omitted. The aligning member 19A is the same as that used in the second embodiment.

[0066] The valve stem 3C differs only in that the circumferential groove 3Cb is shifted upward from the return flow path 23, and other configurations are the same as those of the first embodiment, so a duplicated description will be omitted.

[0067] The holder 11C comprises a cylindrical main body 11Ca, a flange portion 11Cb extending radially outward from the upper end of the main body 11Ca and joined to the lower end of the can 50, and a cylindrical, bottomed retaining portion 11Cd joined to the lower end of the main body 11Ca. A male thread 11Cc is formed on the outer periphery of the lower part of the main body 11Ca. The configuration of the holder 11C other than the retaining portion 11Cd is the same as that of the first embodiment, so a repeated description will be omitted.

[0068] The bottom wall of the retaining portion 11Cd has a through-hole 11Ce at its center, into which the valve stem 3C slidably fits. A retaining ring 41 engages with a circumferential groove 3Cb formed radially inward of the main body 11Ca in the valve stem 3C. A coil spring (also simply referred to as a spring) 4 is arranged in a compressed state around the valve stem 3C 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] The motor-operated valve 1C of this embodiment is configured such that, instead of forming an accommodation portion for the coil spring 4 in the valve body 2C, a holding portion 11Cd is provided in a part of the holder 11C as an accommodation portion for the coil spring 4. With this configuration, the valve stem 3C, the valve body 2C, and the motor unit 100 (excluding the stator unit) can be handled as a single module. Therefore, the single module can be pre-assembled and then attached to the valve body 2C in a single step, improving assembly efficiency.

[0070] The present invention is not limited to the above-described embodiment. Any of the components of the above-described embodiment may be modified within the scope of the present invention. Any of the components may be added or omitted in the above-described embodiment. For example, while an example has been given in which a planetary gear mechanism is used as the reduction mechanism, this is not limiting and a gear pair may also be used. Furthermore, although the axis of the valve stem intersects with the axis of the return flow path in this embodiment, the axis of the valve stem does not have to intersect with the axis of the return flow path, and the valve stem does not have to intersect with the return flow path itself.

[0071] This specification includes the following disclosure of the invention: (First Aspect) An electrically operated valve comprising: a valve body having a first flow path through which a refrigerant is introduced, a second flow path through which the refrigerant flows out, 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 having a valve element portion capable of seating on the valve seat, a motor disposed in the valve body on the opposite side of the third flow path from the valve seat, and a conversion mechanism that converts rotation of a rotor of the motor into linear movement and transmits the linear movement to the valve stem.

[0072] (Second Aspect) The motor-operated valve of the first aspect, characterized in that it comprises a rotor of the motor, a reduction mechanism that reduces the rotation of the rotor of the motor, the conversion mechanism that converts the rotation reduced by the reduction mechanism into linear movement, and a can that houses at least the reduction mechanism, the interior of which is connected to the third flow path.

[0073] (Third aspect) The motor-operated valve of the first or second aspect, characterized in that a drive member that rotates and displaces axially, and a ball seat with a spherical end that is fixed to the valve stem are arranged between the conversion mechanism and the valve stem, and the axial displacement of the drive member is transmitted to the valve stem when a ball fixed to the drive member abuts against the end of the ball seat.

[0074] (Fourth Aspect) The motor-operated valve according to the third aspect, further comprising a rotation limiting mechanism that limits rotation of the valve stem relative to the valve body.

[0075] (Fifth Aspect) The motor-operated valve of the fourth aspect, characterized in that the rotation limiting mechanism comprises a limiting member fixed to the valve body and having a non-cylindrical opening, and the valve stem body having a non-cylindrical shape that engages with the opening.

[0076] (Sixth Aspect) The motor-operated valve of any one of the first to fifth aspects, characterized in that the valve shaft body comprises a first shaft having the valve body portion that seats on the valve seat, and a second shaft connected to the first shaft and having the ball seat, and 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.

[0077] (Seventh Aspect) The motor-operated valve of the sixth aspect, characterized in that the end of the first shaft has a conical shape, the end of the second shaft has a spherical shape, the conical end and the spherical end abut each other, and the abutment surface diameter of the ball and the ball seat is smaller than the abutment surface diameter of the conical end and the spherical end.

[0078] (Eighth Aspect) An electrically operated valve according to any one of the first to fifth aspects, characterized in that the valve stem is made of a single rod-shaped member, and has aligning members attached to the valve body and abutting against the outer periphery of the valve stem at multiple points along the circumferential direction to impart elastic force.

[0079] (Ninth Aspect) The motor-operated valve of any one of the first to eighth aspects, characterized in that a cylindrical holder is provided to fix a screw bearing member having a female thread that constitutes the conversion mechanism to the valve body, and the holder has a retaining portion that retains a spring that biases the valve stem in the valve closing direction.

[0080] (Tenth Aspect) The motor-operated valve according to any one of the first to ninth aspects, wherein the motor-operated valve is used in a refrigeration cycle, and refrigerant from a condenser is introduced into the first flow path, refrigerant flows out from the second flow path toward an evaporator, and refrigerant from the evaporator passes through the third flow path.

[0081] DESCRIPTION OF SYMBOLS 1, 1A: Motor-operated valve 2, 2A: Valve body 3, 3A: Valve stem 3a, 31Aa: Valve body portion 4: Coil spring 5: Stepping motor 6: Speed ​​reducing mechanism 20: Valve seat 21: First flow path 22: Second flow path 23: Return flow path (third flow path) 27: Annular hole portion 31A: Lower shaft 32A: Upper shaft 50: Can 55: Stator 57: Rotor 100: Motor unit VC: Valve chest

Claims

1. An electrically operated valve comprising: a valve body having a first flow path through which a refrigerant is introduced, a second flow path through which the refrigerant flows out, a third flow path through which the refrigerant passes, and a valve seat formed between the first and second flow paths; a valve stem having a valve body portion capable of seating on the valve seat; a motor disposed in the valve body on the opposite side of the third flow path from the valve seat; and a conversion mechanism which converts the rotation of a rotor of the motor into linear movement and transmits the linear movement to the valve stem.

2. The motor-operated valve according to claim 1, further comprising a rotor of the motor, a speed reduction mechanism for reducing the speed of the rotor of the motor, a conversion mechanism for converting the rotation reduced by the speed reduction mechanism into linear movement, and a can housing at least the speed reduction mechanism, the interior of which is connected to the third flow path.

3. The motor-operated valve according to claim 1, characterized in that a drive member which rotates and displaces axially, and a ball seat with a spherical end fixed to the valve shaft are disposed between the conversion mechanism and the valve shaft, and the axial displacement of the drive member is transmitted to the valve shaft when a ball fixed to the drive member abuts against the end of the ball seat.

4. The motor-operated valve according to claim 3, further comprising a rotation limiting mechanism for limiting rotation of the valve stem relative to the valve body.

5. The motor-operated valve according to claim 4, characterized in that the rotation limiting mechanism comprises a limiting member fixed to the valve body and having a non-cylindrical opening, and the valve shaft body having a non-cylindrical shape that engages with the opening.

6. The motor-operated valve according to claim 3, characterized in that the valve shaft body comprises a first shaft having the valve body portion that seats on the valve seat, and a second shaft connected to the first shaft and having the ball seat, and 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.

7. The motor-operated valve according to claim 6, characterized in that the end of the first shaft has a conical shape and the end of the second shaft has a spherical shape, the conical end and the spherical end abut against each other, and the abutment surface diameter of the ball and the ball seat is smaller than the abutment surface diameter of the conical end and the spherical end.

8. The motor-operated valve according to claim 3, characterized in that the valve stem comprises a single rod-shaped member, and has aligning members attached to the valve body and abutting against the outer periphery of the valve stem at multiple points along the circumferential direction to impart elastic force.

9. The motor-operated valve according to claim 1, characterized in that a cylindrical holder is provided to fix a screw bearing member having an internal thread constituting the conversion mechanism to the valve body, and the holder has a retaining portion which retains a spring which biases the valve shaft in the valve closing direction.

10. The motor-operated valve according to claim 1, characterized in that the motor-operated valve is used in a refrigeration cycle, and refrigerant from a condenser is introduced into the first flow path, refrigerant flows out from the second flow path toward an evaporator, and refrigerant from the evaporator passes through the third flow path.

Images