Electronic expansion valve

Abstract

The invention provides an electronic expansion valve which is characterized in that the electronic expansion valve comprises a valve body assembly, a first supporting piece, a valve rod and a spring, and the first supporting piece is fixedly connected with the valve body assembly; the valve rod can axially move relative to the first supporting piece, the first supporting piece is provided with a supporting step portion, the valve rod comprises a spring check ring, the spring check ring and the valve rod are fixedly connected or are of an integrated structure, one end of the spring abuts against the spring check ring, and the other end of the spring abuts against the valve rod. The other end of the spring is directly or indirectly propped against the supporting step part; and the spring is always in a compressed state, and the spring retainer ring is always subjected to the spring force of the spring.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and in particular to an electronic expansion valve. Background Technology

[0002] Electronic expansion valves typically incorporate a transmission mechanism that converts rotational motion into linear motion. This mechanism usually consists of a lead screw with external threads and a nut with internal threads. Taking an electronic expansion valve where the nut moves up and down due to the threaded movement as an example, the nut is fixedly connected to the valve core and drives the valve core to move up and down. To ensure proper assembly and operation, a certain axial clearance must be maintained between the internal thread of the nut and the external thread of the lead screw. During the opening or closing process of the electronic expansion valve, due to the existence of the axial clearance, the thread clearance must be compensated before the valve core can move, resulting in a certain pulse lag. That is, during the opening process, the lead screw drives the nut upward, and the lead screw contacts the upper end face of the nut's thread; during the closing process, the lead screw pushes the nut downward, and the lead screw contacts the lower end face of the nut's thread. Summary of the Invention

[0003] The purpose of this invention is to provide an electronic expansion valve that can reduce the problem of sluggish operation caused by thread clearance.

[0004] To achieve the above objectives, the present invention provides an electronic expansion valve, characterized in that it includes a valve body assembly, a first support member, a valve stem, and a spring; the first support member is fixedly connected to the valve body assembly; the valve stem is axially displaceable relative to the first support member; the first support member is provided with a support step portion; the valve stem includes a spring retainer ring, the spring retainer ring is fixedly connected to the valve stem or is an integral structure; one end of the spring abuts against the spring retainer ring, and the other end of the spring abuts directly or indirectly against the support step portion; the spring is always in a compressed state, and the spring retainer ring is always subjected to the spring force of the spring.

[0005] In the above technical solution, the spring retainer is always subjected to the spring force. Since the spring retainer is fixed to the valve stem or is an integral structure, and the nut is fixedly connected to the valve stem or is limited to a certain position, the nut is always subjected to the upward spring force of the spring, which can reduce or eliminate the problem of sluggish action caused by thread clearance. Attached Figure Description

[0006] Figure 1 A cross-sectional schematic diagram of the electronic expansion valve provided in this application;

[0007] Figure 2 yes Figure 1 Enlarged view of Part I;

[0008] Figure 3A schematic diagram of the supporting components;

[0009] Figure 4 This is a schematic diagram of the structure of the limiting retaining ring;

[0010] Figure 5 This is a structural diagram of the execution component;

[0011] Figure 6 This is a schematic diagram of the nut assembly.

[0012] Figure 7 This is a schematic diagram of the structure of the nut retaining ring;

[0013] Figure 8 This is a schematic diagram of the lead screw structure;

[0014] Figure 9 This is a schematic diagram of the threaded fit between the nut and the lead screw. Detailed Implementation

[0015] The specific embodiments of the present invention will be described below with reference to the accompanying drawings, so that those skilled in the art can accurately understand the technical solution of the present invention.

[0016] The axial, circumferential, and radial directions mentioned in this article are all based on the electronic expansion valve. The axial direction is the extension direction of the central axis of the electronic expansion valve. In the horizontal plane perpendicular to the axial direction, the rotation direction of the rotor of the electronic expansion valve is the circumferential direction, and the extension direction of the rotor's diameter is the radial direction. When the subject described only involves the nut assembly, the extension direction of the central axis of the nut assembly is the axial direction, the circumferential direction is the direction of the cylindrical surface of the nut, and the radial direction is the direction of the nut's diameter.

[0017] The "up" and "down" in this article refer only to the orientation shown in the attached diagram and are for illustrative purposes only. They should not be construed as limitations on the usage environment or structure of the electronic expansion valve or nut assembly.

[0018] Please refer to Figure 1 , Figure 2 ,in, Figure 1 This is a cross-sectional schematic diagram of the electronic expansion valve provided in this application. Figure 2 yes Figure 1 Enlarged view of part I.

[0019] The electronic expansion valve includes a valve body component 100 and a coil component. The coil component is sleeved on the outer periphery of the valve body component 100 and is limitedly connected to the valve body component 100 to maintain a fixed axial relative position. The valve body component 100 includes a valve body assembly 10, an actuator assembly 20, a nut assembly 30, a support assembly 40, a reduction mechanism 50, a rotor assembly 60, a lead screw 80, and a housing 70. Its operating principle is as follows: when the coil component is energized, it generates electromagnetic force, driving the rotor assembly 60 to rotate. The rotation of the rotor is reduced by the reduction mechanism 50, and then converted into linear motion through the cooperation of the lead screw 80 and the nut 30, which is transmitted to the actuator assembly 20. The valve core of the actuator assembly 20 moves linearly along the direction of opening or closing the valve port, thereby controlling the opening degree of the electronic expansion valve.

[0020] The valve body assembly 10 includes a valve seat 11 and a valve body 12. The valve body 12 may be made of a thin-walled component, generally cylindrical, with a first interface portion 121 on its side wall. A first connecting pipe 122 is fixedly connected to the first interface portion 121. The valve seat 11 is located at the bottom of the valve body 12 and is fixedly connected to the valve body. The valve seat 11 is provided with a valve port 111, and a second interface portion 112 is provided at the bottom of the valve seat 11. A second connecting pipe 113 is fixedly connected to the second interface portion 112. The valve seat 11, the valve body 12, and the first support member 401 described below substantially define a first valve chamber A. Fluid can flow into the first valve chamber A from the first connecting pipe 122, pass through the valve port 111, and flow out from the second connecting pipe 113. Conversely, fluid can also flow in from the second connecting pipe 111, pass through the valve port 111 into the first valve chamber A, and flow out from the first connecting pipe 122. The terms "first" and "second" used in this article are only used to distinguish between two or more components with the same or similar structure, or two or more structures with the same or similar structure, and do not indicate any special limitation on the order.

[0021] Please refer to Figure 3 , Figure 3This is a schematic diagram of the support assembly. The support assembly 40 includes a first support member 41 and a second support member 43. The first support member 41 is fixedly connected to the valve body 12. Specifically, the outer edge of the first support member 41 is provided with a mating part 411 and a stepped part 412. The first support member 41 mates with the inner edge of the valve body 12 through the mating part, and achieves axial positioning with the valve body 12 through the stepped part 412. The first support member 41 includes a large-diameter part 413 and a small-diameter part 414. The large-diameter part 413 is located on the side closer to the second support member 43, and the small-diameter part is located on the side away from the second support member 43. The inner wall of the small-diameter part 414 forms the support member mating part 40131, which can be used to guide the valve core and mate with the sealing member 22 to achieve a seal. The terms "large diameter portion" and "small diameter portion" as used here refer to the inner diameter of the first support member 41. Thus, a support step portion 415 is formed between the large diameter portion and the small diameter portion. The support step portion 415 can be used to abut and fix with the limiting retaining ring 42 described below. Please refer to... Figure 4 , Figure 4 This is a schematic diagram of the limiting retaining ring 42. The limiting retaining ring 42 is a generally annular thin plate. The outer diameter of its outer edge is adapted to the inner diameter of the large diameter portion 413 of the first support member 41. The limiting retaining ring 42 has a through hole 421 extending through its thickness direction. The mating portion forming the edge of the through hole 421 includes at least one non-circular arc mating surface. In this embodiment, the limiting retaining ring includes a first straight segment 422 and a second straight segment 423, which are arranged opposite to each other and symmetrically. The first straight segment 422 and the second straight segment 423 are used to mate with the valve stem mating portion of the valve stem 24 described below to limit the circumferential rotation of the valve stem. The limiting retaining ring 42 and the first support member 41 can be fixedly connected by interference fit or welding.

[0022] The top 416 of the first support member 41 is fixedly connected to the second support member 43, which is vertically continuous. A bearing 44 is fixedly connected to the inner edge of the second support member 43. The bearing 44 has a bearing through hole 441 for the lead screw 80 (described below) to pass through. Thus, the first support member 41, the second support member 43, the retaining ring 42, and the valve stem 24 (described below) substantially define the second valve cavity B. The first support member 41 forms part of the wall of the second valve cavity B, and the second support member 43 also forms part of the wall of the second valve cavity B. The bearing 44 includes an outer ring 442 and an inner ring 443. The inner ring 443 has an inner ring bottom surface 4431, which can abut against the boss portion of the lead screw (described below). The second support member 43 is provided with a bearing mounting hole 431. The outer ring 442 is located in the bearing mounting hole 431 and is fixedly or retainingly connected to the bearing mounting hole 431. Fixed connections can be achieved using an interference fit, while limiting connections can be achieved using a clearance fit, with the limiting mechanism provided by the boss portion of the lead screw.

[0023] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the actuator assembly. The actuator assembly 20 includes a valve core 21, a valve stem 24, a sealing component 22, a sealing retaining ring 23, and a spring retaining ring 25. The valve stem 24 is generally cylindrical and has a central hole 211, which allows fluid flow through the valve stem. A side through hole 212 is provided on the side wall of the valve stem 24. The inner cavity of the valve stem has a nut receiving cavity 213 and a nut retaining ring receiving cavity 214, with the nut receiving cavity 213 being closer to the side through hole 212 than the nut retaining ring receiving cavity 214. The nut receiving cavity 213 is used to assemble a nut 31, and the nut retaining ring receiving cavity 214 is used to assemble a nut retaining ring 32. The outer wall of the valve stem 24 is provided with a valve stem mating portion. In this embodiment, the valve stem mating portion includes a first valve stem mating portion 215 and a second valve stem mating portion 216. Specifically, the first valve stem mating portion 215 and the second valve stem mating portion 216 can be machined by milling, milling two planes on the side of the valve stem. In this embodiment, the first valve stem mating portion 215 and the second valve stem mating portion 216 can be symmetrically arranged on both sides of the valve stem. The first valve stem mating portion 215 and the second valve stem mating portion 216 can respectively mate with the through hole of the limiting retaining ring. Specifically, the first valve stem mating portion 215 and the second valve stem mating portion 216 can respectively mate with the first straight section 422 and the second straight section 423 of the limiting retaining ring 42, thereby restricting the rotation of the valve stem. Since the limiting retaining ring 42 and the first support member 41 can be fixedly connected by interference fit or welding, the valve stem 24 is constrained and cannot rotate. A spring retaining ring 25 is fixed to the top of the valve stem, such as Figure 5 As shown, the valve stem 24 has a valve stem boss 241 at its top. The spring retainer 25 is generally annular in shape and can be fitted onto the lower end of the valve stem 24, abutting against the valve stem boss 241 for positioning. Specifically, the spring retainer 25 and the valve stem 24 can be fixedly connected by interference fit or welding. The lower end of the spring retainer has a first abutment portion 251 for abutting against the spring described below. In this embodiment, the spring retainer 25 is a separate component, fixedly connected to the valve stem 24 after assembly. Alternatively, the spring retainer 25 and the valve stem 24 can be machined as a single piece, for example, by machining the spring retainer 25 directly onto one end of the valve stem.

[0024] The valve core 21 is fixedly connected to the valve stem 24, specifically, by means of interference fit or riveting. A sealing ring 23 and a sealing component 22 are provided between the valve core 21 and the valve stem 24. The outer periphery of the valve core 21 near the valve stem end is provided with a first step portion 216 and a second step portion 217, wherein the second step portion 217 is closer to the valve stem than the first step portion 216. The sealing ring 23 abuts against the second step portion 217, thus forming an annular space between the sealing ring 23 and the first step portion 216, and at least a portion of the sealing component 22 is located within this annular space. When the actuator 20 is assembled to the first support member 41, the sealing component 22 can cooperate with the support member mating part 40131 during movement to achieve a seal. In this embodiment, the sealing component 22 includes an O-ring 212 and a sealing ring 221. The O-ring can be made of materials such as rubber and can abut against the valve core to achieve a seal. The sealing ring 221 is located on the outer periphery of the O-ring 212 and is used for sliding contact with the support member mating part 40131. The sealing ring 221 can be made of PTFE material, which has good self-lubricating properties, can provide good mating performance, and reduce wear. The sealing component 22 isolates the first support member 41 and the valve core 21. In other words, when the valve core 21 is in the closed state, that is, when the valve core 21 abuts against the valve port 111, the first valve chamber A and the second valve chamber B cannot be connected through the mating gap between the valve core and the first support member 41. At this time, the fluid in the second valve chamber B can communicate with the second connecting pipe 113 through the side through hole 212 and the valve stem center hole 211. In this way, the fluid pressure difference between the second valve chamber B and the second connecting pipe 113 is small, which is beneficial for the spring 90 to accurately control the valve stem.

[0025] Please refer to Figure 6 , Figure 7 , Figure 6 This is a structural diagram of the nut assembly. Figure 7This is a schematic diagram of the nut retainer ring. The nut assembly 30 includes a nut 31 and a nut retainer ring 32. The nut 31 includes a nut body portion 314 and an internal thread portion 311. The internal thread portion 311 is used to cooperate with the external thread portion 801 of the lead screw 80 to form a helical feeding mechanism. In this way, when the lead screw 80 rotates, it can drive the nut 31 to undergo axial displacement while rotating. The outer diameter of the nut 31 is adapted to the inner diameter of the nut receiving cavity 213, or the outer diameter of the nut 31 is slightly smaller than the inner diameter of the nut receiving cavity 213. A first groove portion 312 is provided on the top of the nut 31. Correspondingly, the nut retainer ring is provided with a second groove portion 321. When the nut retainer ring 32 is assembled with the nut 31, the first groove portion 312 and the second groove portion 321 fit together with a small gap. After the nut retainer ring 32 is assembled with the valve stem 24, it can be fixedly connected by welding. A small radial and axial clearance is provided between the nut retaining ring 32 and the nut 31, which allows for automatic centering of the nut. Furthermore, due to the fit between the first groove portion 312 and the second groove portion 321, the relative position between the nut 31 and the valve stem 24 is fixed; that is, the nut 31 cannot rotate significantly relative to the valve stem 24, and can only perform minor radial or axial movements within a small range of clearance. In a specific embodiment, the radial clearance between the outer periphery of the nut 31 and the nut receiving cavity can be set between 0.05mm and 0.5mm, and the axial clearance of the nut 31 is configured between the nut 31 and the nut retaining ring 32, specifically between 0.05mm and 0.2mm.

[0026] Please refer to Figure 8 , Figure 8 This is a schematic diagram of the lead screw structure. The lead screw 80 has an external threaded portion 801 at its lower part, which mates with the internal threaded portion of the nut. A boss portion 803 is located in the middle of the lead screw 80. A bearing mating portion 802 is formed on the outer edge above the boss portion 803. The bearing mating portion 802 mates with the inner ring 443 of the bearing, allowing for a small clearance fit. The outer diameter of the boss portion 803 is larger than the outer diameter of the bearing mating portion 802. Thus, after the lead screw and bearing are assembled, the bearing abutment portion 8031 ​​formed by the boss portion 803 can abut against the bottom surface 4431 of the inner ring of the bearing, thereby providing support for the bearing. An insert portion 804 is located at the top of the lead screw 80. Specifically, the insert portion 804 can be designed with a non-circular cross-section, for example... Figure 8 The cut can create one or more planes, or it can be set to other irregular structures, as long as it can match the corresponding structure of the output shaft of the reduction mechanism and can transmit rotation.

[0027] The outer casing 70 is fixedly connected to the first support member 41, such that the first support member 41, the second support member 43, and the outer casing 70 substantially define the third cavity C, and at least a portion of the reduction mechanism 50 and the magnetic rotor assembly 60 are located in the third cavity C. The reduction mechanism 50 is fixedly connected to the second support member 43. The reduction mechanism includes a multi-stage reduction gear 501, such as... Figure 1 As shown, the magnetic rotor assembly 60 can rotate under the electromagnetic force of an electromagnetic coil (not shown in the figure), and after being reduced in speed by a multi-stage gear reduction mechanism 50, it drives the output shaft 601 to rotate. The output shaft 601 cooperates with the lead screw insertion part 804 to drive the lead screw 80 to rotate.

[0028] Spring 90 is located in the second valve chamber B. Spring 90 can be a cylindrical spring with both ends tightly closed and ground flat. One end of spring 90 abuts against spring retaining ring 25, and the other end of spring 90 abuts directly or indirectly against limiting retaining ring 42. Figure 1 In the illustrated technical solution, the spring 90 directly abuts against the limiting retaining ring 42. This limiting retaining ring serves both as a component to prevent circumferential rotation of the valve stem and as a component to support the spring 90. Alternatively, the spring 90 can be configured to directly abut against the first support member. Furthermore, the spring 90 is configured such that it remains compressed throughout the entire opening and closing process of the valve body. Alternatively, it can be understood that during the opening and closing of the electronic expansion valve, the nut 31 moves up and down due to the threaded interaction with the lead screw 80, causing the spring retaining ring 25 to move away from or closer to the limiting retaining ring 42. That is, the axial distance between the spring retaining ring 25 and the limiting retaining ring 42 changes. Since the initial height of the spring 90 is greater than the maximum distance between the spring retaining ring 25 and the limiting retaining ring during operation, the spring 90 remains compressed and consistently provides an upward spring force to the spring retaining ring 25.

[0029] Please refer to Figure 9 , Figure 9 This is a schematic diagram of the threaded fit between a nut and a lead screw. Definition: On a cross-section in the axial direction, with... Figure 9 Based on the protruding portion of the external thread portion 801 of the lead screw 80, the external thread portion 801 of the lead screw 80 includes several upper external thread faces 8012 and lower external thread faces 8011. Based on the recessed portion of the internal thread portion 311 of the nut 31, the internal thread portion 311 of the nut 31 includes several upper internal thread faces 3112 and lower internal thread faces 3111. The above definitions of the upper and lower end faces of the lead screw and nut also apply to the solutions described in the background art. Figure 9In the shown state, the upper end face 8012 of the external thread of the external thread portion 801 and the upper end face 3112 of the internal thread of the internal thread portion 311 have a preset distance D in the axial direction. Since the spring 90 always applies an upward spring force to the nut 31, the lower end face 3111 of the internal thread always abuts against the lower end face 8011 of the external thread. The spring force that the spring 90 always applies to the spring retainer 25 is indirectly transmitted to the nut 31, so that the nut 31 is also always subjected to an upward spring force. Therefore, regardless of whether the valve body is opening or closing the valve, the threaded part of the nut is always in contact with the lower end face 3111 of the internal thread and the lower end face 8011 of the external thread of the lead screw, and is not affected by the direction of action. Thus, the problem of action delay caused by thread clearance can be reduced or eliminated.

[0030] Furthermore, due to the spring force, the lead screw 80 is always subjected to an upward force, and indirectly, the bearing 44 is also always subjected to an upward force. Therefore, the bearing part can reduce its dependence on axial limiting. That is, in the embodiments of this application, even if a bearing retaining ring to prevent the bearing 44 from falling off is not provided below the bearing 44, or the bearing is only placed in the bearing mounting hole, or only the bearing is clearance-fitted with the bearing mounting hole, the reliability of the bearing installation can be ensured, which can reduce costs and improve assembly efficiency.

[0031] It is understood that although this article describes a specific electronic expansion valve structure, the core of the present invention lies in the cooperative structure of the spring and support and the actuator. Other components or assemblies of the electronic expansion valve, such as coils, transmission mechanisms, reduction mechanisms, and rotors, are only introduced to facilitate those skilled in the art to understand the working principle of the electronic expansion valve, and are not intended to limit the aforementioned other components or assemblies.

Claims

1. An electronic expansion valve, characterized in that, The system includes a valve body assembly (10), a first support member (41), a valve stem (24), a nut (31), and a spring (90). The first support member (41) is fixedly connected to the valve body assembly (10). The valve stem (24) is axially displaceable relative to the first support member (41). The nut (31) is fixedly connected to or limited by the valve stem (24). The first support member (41) is provided with a support step (415). The valve stem (24) includes a spring retainer (25). The spring retainer (25) is fixedly connected to the valve stem (24) or is an integral structure. One end of the spring (90) abuts against the spring retainer (25), and the other end of the spring (90) abuts directly or indirectly against the support step (415). The spring (90) is always in a compressed state, and the spring retainer (25) is always subjected to the spring force of the spring (90).

2. The electronic expansion valve as described in claim 1, characterized in that, It also includes a limiting ring (42), which is fixedly connected to the first support member (41). The limiting ring (42) abuts against the support step (415). The spring (90) abuts against the limiting ring (42) to achieve indirect contact between the spring (90) and the support step (415).

3. The electronic expansion valve as described in claim 2, characterized in that, The limiting retaining ring (42) includes a through hole (421) extending through the thickness direction. The edge of the through hole (421) includes at least one non-circular arc mating surface. The valve stem (24) includes a valve stem mating part. The through hole (421) mates with the valve stem mating part and restricts the circumferential rotation of the valve stem (42).

4. The electronic expansion valve as described in claim 1 or 2, characterized in that, The electronic expansion valve includes a second valve chamber (B), the first support (41) forms part of the wall of the second valve chamber (B), and the spring (90) is located in the second valve chamber (B).

5. The electronic expansion valve as described in claim 1 or 2, characterized in that, The electronic expansion valve includes a lead screw (80), the inner cavity of the valve stem (24) is provided with a nut receiving cavity (231), the nut (31) is located in the nut receiving cavity (231), the spring force of the spring (90) is applied to the nut (31) through the valve stem (24), the lead screw (80) is provided with an external thread (801), the nut (31) is provided with an internal thread (311), and the external thread (801) and the internal thread (311) are threadedly engaged.

6. The electronic expansion valve as described in claim 5, characterized in that, The internal thread portion (311) includes several internal thread upper end faces (3112) and internal thread lower end faces (3111), and the external thread portion (801) includes several external thread upper end faces (8012) and external thread lower end faces (8011). The internal thread upper end faces (3112) and the external thread upper end faces (8012) have a preset distance in the axial direction, and the internal thread lower end face (3111) always abuts against the external thread lower end face (8011).

7. The electronic expansion valve as described in claim 1 or 2, characterized in that, The electronic expansion valve includes a second support member (43) and a lead screw (80). The inner edge of the second support member (43) is provided with a bearing (44). The bearing (44) is provided with a bearing through hole (441). At least a portion of the lead screw (80) passes through the bearing shaft hole (441) and abuts against the bearing (44).

8. The electronic expansion valve as described in claim 7, characterized in that, The bearing (44) includes an inner ring (443), the inner ring (443) includes a bottom surface (4431), and the lead screw (80) is provided with a boss (803), the boss (803) always abutting against the bottom surface (4431) of the inner ring.

9. The electronic expansion valve as described in claim 8, characterized in that, The outer edge of the boss (803) is provided with a bearing mating part (802), and the bearing inner ring (443) is mated with the bearing mating part (802) with a small clearance.

10. The electronic expansion valve as described in claim 7, characterized in that, The bearing includes a bearing outer ring (442), and the second support member (43) is provided with a bearing mounting hole (431). The bearing outer ring (442) is located in the bearing mounting hole (431), and the bearing outer ring (442) is fixedly connected and limited to the bearing mounting hole (431).

Images