Motorised valve

Abstract

An electric valve comprises a thin-walled section, a first part and a support part, the thin-walled section is located at the outer periphery of the support part, at least part of the support part abuts against the thin-walled section, the first part and the thin-walled section are welded and fixed by friction stir welding, the end face diameter of the shaft shoulder of the stir head is defined as Φd, along the axial direction of the support part, the height of the abutting part of the support part and the thin-walled section is h, along the radial direction of the support part, the thickness of the support part is T, and the three satisfy the relationship: T≥h, h>0.25×Φd, by setting the support part to abut against the thin-walled section and specifically designing the size relationship of the support part suitable for friction stir welding, the radial pressure applied by the stir head to the thin-walled section during welding can be offset or partially offset, and the deformation of the thin-walled section can be reduced.

Description

TECHNICAL FIELD

[0001] The application relates to an electric valve. BACKGROUND

[0002] The electric valve is commonly used for on-off and switching of fluid in a vehicle thermal management system or an air conditioning system, and the electric valve comprises a gear box and a valve body, and the gear box and the valve body are commonly fixed by welding. The inventor has found that the gear and the valve body are both made of aluminum material, and the gear box and the valve body are welded by friction stir welding in order to ensure the welding quality. In order to make the electric valve compact, the welding position of the gear box for welding with the valve body is in a thin-wall structure. However, the thin-wall structure is prone to severe deformation of the welding position during welding. How to design a suitable welding structure to reduce the deformation of the welding position is a technical problem to be improved. SUMMARY

[0003] The application aims to provide an electric valve which is beneficial to reduce the deformation of the welding position of the electric valve caused by welding.

[0004] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0005] An electric valve comprises a gear box and a main valve body, the gear box comprises a thin-wall section, the main valve body comprises a first part, the thin-wall section and the first part are fixed by friction stir welding, the main valve body further comprises a support part, the support part is formed by protruding upward from an upper end surface of the first part, the thin-wall section is located at an outer periphery of the support part, at least part of the support part abuts against the thin-wall section, the diameter of an end surface of a shaft shoulder of a stirring head is defined as Φd, the height of the abutting part of the support part and the thin-wall section along the axial direction of the support part is defined as h, and the thickness of the support part along the radial direction of the support part is defined as T, and the three satisfy the relationship: T >= h, and h > 0.25 * Φd.

[0006] The application provides an electric valve comprising a thin-wall section, a first part and a support part, the thin-wall section is located at an outer periphery of the support part, at least part of the support part abuts against the thin-wall section, the first part and the thin-wall section are fixed by friction stir welding, the diameter of an end surface of a shaft shoulder of a stirring head is defined as Φd, the height of the abutting part of the support part and the thin-wall section along the axial direction of the support part is defined as h, and the thickness of the support part along the radial direction of the support part is defined as T, and the three satisfy the relationship: T >= h, and h > 0.25 * Φd. By abutting the support part against the thin-wall section and specifically designing the size relationship of the support part suitable for friction stir welding, the radial pressure applied by the stirring head to the thin-wall section during welding is offset or partially offset, and the deformation of the thin-wall section is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a schematic view of a cross section structure of the first embodiment of the electric valve;

[0008] Figure 2 is a sectional view of the valve body assembly of the electric valve; Figure 1

[0009] Figure 3 is an exploded view of the transmission mechanism;

[0010] Figure 4 is a sectional view of the electric valve; Figure 1 is a partial enlarged view of part A in the electric valve;

[0011] Figure 5 is a front view of the stirring head;

[0012] Figure 6 is a sectional view of the electric valve; Figure 5 is a partial enlarged view of part B in the electric valve;

[0013] Figure 7 is a perspective view of the first embodiment of the electric valve;

[0014] Figure 8 is another sectional view of the first embodiment of the electric valve;

[0015] Figure 9 is a sectional view of the second embodiment of the electric valve;

[0016] Figure 10 is a sectional view of the electric valve; Figure 9 is a partial enlarged view of part C in the electric valve. DETAILED DESCRIPTION

[0017] The present application will be further described below in conjunction with the drawings and specific embodiments:

[0018] Referring to Figure 1 , the electric valve 100 can be applied to a vehicle thermal management system or an air conditioning system, including a new energy vehicle thermal management system. The electric valve 100 comprises a driving mechanism 1, a transmission mechanism 2, a valve body assembly 3, a valve rod 4, and a valve core 5. The driving mechanism 1 is in transmission connection with the transmission mechanism 2. The transmission mechanism 2 is in transmission connection with one end of the valve rod 4. The other end of the valve rod 4 is in transmission connection with the valve core 5. The valve core 5 is located in a valve body cavity 30 formed by the valve body assembly 3. The driving mechanism 1 outputs a rotating torque to the transmission mechanism 2. The transmission mechanism 2 increases the rotating torque output by the driving mechanism 1 and then transmits it to the valve rod 4. The valve rod 4 then drives the valve core 5 to rotate. The transmission mechanism 2 can be a gear transmission mechanism. In this embodiment, the transmission mechanism 2 is a planetary gear reduction mechanism.

[0019] Referring to Figure 1 ​The driving mechanism 1 comprises an outer housing 11, a motor assembly 12, a sleeve 13, a connecting seat 14 and a circuit board 15. The motor assembly 12 comprises a coil winding 121, a rotor assembly 122, a motor shaft 123 and a first pin 124. The sleeve 13 comprises a tube body 131 and a cover plate 132 which are connected and fixed. Alternatively, the tube body 131 and the cover plate 132 can be integrally formed. The coil winding 121 and the first pin 124 are injection-molded inserts, and the outer housing 11 is integrally injection molded. The driving mechanism 1 has a containing cavity 10, and the circuit board 15 is located in the containing cavity 10. One end of the first pin 124 is electrically and / or signal connected with the coil winding 121, and the other end of the first pin 124 is electrically and / or signal connected with the circuit board 15. The rotor assembly 122 is connected and fixed with the motor shaft 123. The sleeve 13 is connected and fixed with the connecting seat 14 through the tube body 131. The sleeve 13 and the connecting seat 14 are assembled to form a rotor cavity 130. The rotor assembly 122 and part of the motor shaft 123 are located in the rotor cavity 130. The coil winding 121 is located outside the sleeve 13. The coil winding 121 and the rotor assembly 122 are separated by the sleeve 13, which is beneficial to avoid the fluid in the rotor cavity 130 from contacting the coil winding 121 and ensures the safety of the coil winding 121. The driving mechanism 1 further comprises an interface part 16 which can be integrally injection molded or assembled and fixed with the outer housing 11. The interface part 16 comprises a second pin 161 and has a plug-in cavity 162. The middle part of the second pin 161 is fixed with the outer housing 11 by injection molding. One end of the second pin 161 is located in the containing cavity 10 and is electrically and / or signal connected with the circuit board 15. The other end of the second pin 161 is located in the plug-in cavity 162 and is electrically and / or signal connected with the outside.

[0020] Referring to Figures 1 to 3The valve body assembly 3 comprises a gear box 31 and a main valve body 32. The gear box 31 comprises a mounting portion 311 forming a mounting cavity 312 in which the connecting seat 14 of the drive mechanism 1 is located and fixedly connected with the mounting portion 311. In the embodiment, the connecting seat 14 is fixedly connected with the mounting portion 311 by a compression nut. Further, a seal can be arranged between the connecting seat 14 and the mounting portion 311 to prevent leakage of the working medium from the assembly gap therebetween. The main valve body 32 is fixedly connected with the gear box 31, and the gear box 31 and the main valve body 32 are assembled to form a first cavity 310. The mounting cavity 312 is in communication with the first cavity 310 with respect to the valve body assembly 3. The transmission mechanism 2 is located in the first cavity 310. In the embodiment, the transmission mechanism 2 is a planetary gear reduction mechanism, which comprises a sun gear 21, a plurality of planet gears 22, a first inner ring gear 23 and a second inner ring gear 24. The number of the planet gears 22 is three, but the number of the planet gears 22 can be other numbers in other embodiments. One end of the motor shaft 123 of the drive mechanism 1 is located in the first cavity 310, and the sun gear 21 is located at the outer periphery of the one end of the motor shaft 123 and is in transmission connection with the motor shaft 123. The first inner ring gear 23 is located in the first cavity 310 and is fixedly connected with the gear box 31, for example, by interference fit. The second inner ring gear 24 is located in the first cavity 310 and is arranged opposite to the first inner ring gear 23 along the axial direction of the gear box 31. The second inner ring gear 24 can rotate circumferentially relative to the first inner ring gear 23, and the rotation range of the second inner ring gear 24 is limited by the limiting column 321 of the main valve body 32. The planet gears 22 are located at the outer periphery of the sun gear 21 and are circumferentially distributed around the sun gear 21. The sun gear 21 is in meshing connection with the planet gears 22, and the planet gears 22 are in meshing connection with the first inner ring gear 23 and the second inner ring gear 24, respectively. Thus, the drive mechanism 1 drives the sun gear 21 to rotate through the motor shaft 123, and the sun gear 21 drives the second inner ring gear 24 to rotate through the planet gears 22. The second inner ring gear 24 is in transmission connection with one end of the valve rod 4, and the other end of the valve rod 4 is located in the valve body cavity 30 and is in transmission connection with the valve core 5. That is, the second inner ring gear 24 drives the valve core 5 to rotate through the valve rod 4, and the electric valve 100 realizes the switching and switching between the passages thereof through the rotation of the valve core 5.

[0021] Referring to Figure 1 and Figure 4In order to reduce the overall weight and manufacturing cost of the electric valve 100, the gear box 31 and the main valve body 32 are both made of aluminum material; in order to ensure the sealing performance of the electric valve 100, the gear box 31 and the main valve body 32 are connected and fixed by welding; in order to make the structure of the electric valve 100 compact, the part of the gear box 31 used for welding with the main valve body 32 is the thin-walled section 313 of the side wall of the gear box 31, along the radial direction of the gear box 31, the thickness B of the thin-walled section 313 is less than 5mm, and the installation gap range between the outer edge of the second inner gear ring 24 and the inner circumferential surface of the thin-walled section 313 is controlled between 1mm and 1.5mm. The main valve body 32 includes a first part 322, and the first part 322 includes an upper end surface 3221, and the gear box 31 and the main valve body 32 are connected and fixed by welding the free end surface 3131 of the thin-walled section 313 and the upper end surface 3221 of the first part 322.

[0022] Common welding methods include laser welding, vacuum electron beam welding, and friction stir welding. In the welding process of aluminum material, laser welding is prone to porosity and cracks, and in the welding process of aluminum material, due to the excessive concentration of energy, the root of the weld is prone to void defects due to the delayed backfilling of molten metal, thereby affecting the welding quality. In the present embodiment, the friction stir welding method is selected for welding between the gear box 31 and the main valve body 32, and the friction stir welding is not sensitive to the assembly gap of the free end surface 3131 and the upper end surface 3221 before welding, or in other words, the assembly gap between the free end surface 3131 and the upper end surface 3221 has little effect on the friction stir welding. Referring to Figures 4 to 6 , the friction stir welding equipment is a stirrer, which includes a stirring head 6, and the stirring head 6 includes a stirring needle 61 and a shaft shoulder 62. During the welding process, the stirring needle 61 generates heat by high-speed rotation with the thin-walled section 313 and the first part 322 respectively, causing the aluminum material to be welded at the welding position to melt, and then the stirring needle 61 gradually extends between the free end surface 3131 and the upper end surface 3221, forming a dense solid-phase weld between the free end surface 3131 and the upper end surface 3221. At this time, the shaft shoulder 62 abuts against the thin-walled section 313 and the first part 322 respectively, and specifically, the end surface of the shaft shoulder 62 abuts against the outer circumferential surface of the thin-walled section 313 and the outer circumferential surface of the first part 322 respectively, and continuously applies a pressure along the radial direction of the gear box 31. Since the thickness B of the thin-walled section 313 is less than 5mm, this easily causes the thin-walled section 313 to deform inwardly under the pressure, and since the installation gap range between the outer edge of the second inner gear ring 24 and the inner circumferential surface of the thin-walled section 313 is controlled between 1mm and 1.5mm, it is possible to limit or block the rotation of the second inner gear ring 24, affecting the transmission effect of the transmission mechanism 2, and further affecting the working performance of the electric valve 100.

[0023] In order to reduce the inward deformation of the thin-walled section 313 during the welding process, referring to Figure 1 and Figure 4The main valve body 32 further comprises a support portion 323. The support portion 323 is protruded upward from the upper end surface 3221 of the first portion 322 along the height direction of the main valve body 32. The support portion 323 extends upward along the height direction of the main valve body 32. At least part of the support portion 323 is located in the first cavity 310. The thin-walled section 313 is located at the outer periphery of the support portion 323. The inner peripheral surface of the thin-walled section 313 abuts against the outer peripheral surface of the support portion 323. The support portion 323 is arranged to support the thin-walled section 313, so as to offset or partially offset the radial pressure applied to the thin-walled section 313 by the shaft shoulder 62 during welding, thereby facilitating reduction of deformation of the thin-walled section 313. In addition, the thin-walled section 313 and the support portion 323 can be in interference fit. The interference fit between the thin-walled section 313 and the support portion 323 facilitates keeping the free end surface 3131 and the upper end surface 322 relatively fixed during welding, thereby facilitating avoidance of welding surface displacement or misalignment during welding, and facilitating guarantee of welding quality.

[0024] Referring to Figure 4 and Figure 7 The main valve body 32 further comprises an arc-receiving groove 324 and a step portion 325. The step portion 325 is arranged farther away from the support portion 323 than the first portion 322 along the height direction of the electric valve 100. In other words, the first portion 322 is located between the support portion 323 and the step portion 325. The step portion 325 is connected to the first portion 322. The arc-receiving groove 324 is formed by inwardly recessing the side wall surface of the step portion 325. In the present embodiment, the arc-receiving groove 324 comprises an arc surface section 3241 and a planar section 3242. The arc surface section 3241 is located on both sides of the planar section 3242. One side of the arc surface section 3241 is connected to the side wall surface of the step portion 325. The other side of the arc surface section 3241 is connected to the planar section 3242. The planar section 3242 is arranged farther away from the side wall surface of the step portion 325 than the arc surface section 3241 along the radial direction of the first portion 322. A second plane is defined. The second plane is perpendicular to the central axis of the first portion 322. The second plane can be, for example, Figure 8The projection of the first part 322 on the second plane is tangent to the projection of the planar section 3242 on the plane. Of course, as other embodiments, the arc collection groove 324 can also be located at other positions of the main valve body 32, and the arc collection groove 324 is arranged farther away from the support part 323 than the first part 322 along the height direction of the electric valve 100. The arc collection groove 324 is connected with the first part 322, and the projection of the arc collection groove 324 on the second plane is at least partially tangent to the projection of the first part on the second plane. The arc collection groove 324 is arranged because the friction stir welding will generate a spoon hole when the welding is finished. If the spoon hole is located at the welding seam, the strength of the welding seam will be affected. In order to ensure the welding quality, the welding arc collection needs to be arranged in the area deviating from the welding position, such as the arc collection groove 324 arranged on the stepped part 325 in the embodiment. In this way, the welding can be performed in the arc collection groove 324 deviating from the welding position, the spoon hole is located in the arc collection groove 324, and the welding quality at the welding position is ensured. In addition, the projection of the planar section 3242 on the plane is tangent to the projection of the first part 322 on the plane, which is beneficial to the smooth transition of the stirring head 6 to the arc collection groove 324 deviating from the welding position when the welding arc is collected.

[0025] Referring to Figure 4 , Figure 6 and Figure 8 , the diameter of the end face of the shaft shoulder 62 for abutting against the outer circumferential surface of the thin-walled section 313 is Φd. In order to reduce the inward deflection deformation of the thin-walled section 313 during the welding process, the height h of the effective abutting part of the support part 323 and the thin-walled section 313 along the axial direction of the support part 323 is greater than 0.25*Φd. This is because in the embodiment, the support part 323 also includes the inverted inclined surface 3231. The inverted inclined surface 3231 is arranged, which is beneficial to the better guidance and interference fit of the thin-walled section 313 and the support part 323 during assembly. Of course, as other embodiments, the support part 323 can also not be provided with the inverted inclined surface 3231. The thickness T between the inner circumferential surface and the outer circumferential surface of the support part 323 along the radial direction of the support part 323 needs to be greater than or equal to the height h of the abutting part of the support part 323 and the thin-walled section 313, that is, T≥h. In the embodiment, the support part 323 also includes the circular arc surface 3232 and the inner circumferential surface. One end of the circular arc surface 3232 is connected with the inner circumferential surface, and the other end of the circular arc surface 3232 is connected with the upper end surface 3221 of the first part. The circular arc surface 3232 is arranged, which is beneficial to preventing stress concentration of the support part 323 during the welding process and improving the support capacity of the support part 323 to the thin-walled section 313. The first plane is defined as the plane passing through the center axis of the support part 323. The first plane can be, for example Figure 4The radius R of the circular arc of the circular arc surface 3232 projected on the first plane is greater than 1 mm in the plane of the cross section. Of course, as another embodiment, the support portion 323 can not include the circular arc surface 3232. In addition, to avoid the collision between the welding head 6 and the main valve body 32 during the arc collection process, the width W of the planar section 3242 of the arc collection groove 324 is designed to be greater than or equal to Φd+1. To ensure the working space of the welding head 6 during welding, the axial height H of the first portion 322 is designed to be greater than or equal to 0.5×(Φd+1); during friction stir welding, it is recommended that the radial pressure applied by the welding head 6 to the thin-walled section 313 be less than or equal to 1960 N (200 kgf), and the end face diameter Φd of the shoulder 61 be greater than 5 mm. The above size design principles are applicable to the circumferential friction stir welding of aluminum materials with a thickness B of the thin-walled section 313 less than 5 mm.

[0026] Referring to Figure 9 and Figure 10For the second embodiment of the electric valve, the second embodiment is different from the first embodiment in that: in the second embodiment, the gear box 31' further comprises a first protruding portion 3132' which is outwardly protruded from the outer circumferential surface of the thin-walled section 313' along the radial direction of the gear box 31', and which is flush with the free end surface 3131' of the thin-walled section 313' along the axial direction of the gear box 31', or in other words, one end surface of the first protruding portion 3132' forms part of the free end surface 3131', and a step is formed between the other end surface of the first protruding portion 3132' and the outer circumferential surface of the thin-walled section 313'. Similarly, the main valve body 32' further comprises a second protruding portion 3222' which is outwardly protruded from the outer circumferential surface of the first portion 322' along the radial direction of the first portion 322', and which is flush with the upper end surface 3221' of the first portion 322' along the axial direction of the first portion 322', or in other words, one end surface of the second protruding portion 3222' forms part of the upper end surface 3221', and a step is formed between the other end surface of the second protruding portion 3222' and the outer circumferential surface of the first portion 322'. The first protruding portion 3132' and the second protruding portion 3222' are provided to increase the abutting thickness of the thin-walled section 313', the first portion 322' and the shaft shoulder 62 of the stirring head, which is conducive to reducing the deformation of the thin-walled section 313' during welding, and to compensate or partially compensate for the local melting of the material of the thin-walled section 313' and / or the first portion 322' caused by welding, which is conducive to ensuring the strength of the thin-walled section 313' and / or the first portion 322'. The protruding thickness b1 of the first protruding portion 3132' along the radial direction of the gear box 31' is greater than or equal to 0.2 mm, and the length L1 of the first protruding portion 3132' along the axial direction of the gear box 31' satisfies the relationship: 0.25 x (Φd+1) ≤ L1 ≤ 0.5 x (Φd+1). The protruding thickness b2 of the second protruding portion 3132' along the radial direction of the first portion 322' is greater than or equal to 0.2 mm, and the length L2 of the second protruding portion 3132' satisfies the relationship: 0.25 x (Φd+1) ≤ L2 ≤ 0.5 x (Φd+1). It should be noted that, in order to facilitate welding, the protruding thickness b1 of the first protruding portion 3132' is consistent with the protruding thickness b2 of the second protruding portion 3132', i.e. b1 = b2. The other parts of the electric valve 100' are basically the same as those of the first embodiment, and will not be described here again.

[0027] It should be noted that the above examples are only used to illustrate the technical solutions described in the present application and do not limit the technical solutions described in the present application. For example, the directions of "front", "rear", "left", "right", "up", "down" and the like are defined. Although the present application has been described in detail with reference to the above examples, it should be understood by those skilled in the art that the skilled in the art can still modify or equivalently replace the present application, and all technical solutions and improvements which do not deviate from the spirit and scope of the present application should be covered within the scope of the claims of the present application.

Claims

1. An electric valve, comprising a gearbox and a main valve body, the gearbox including a thin-walled section, the main valve body including a first part, the thin-walled section and the first part being fixed by friction stir welding, characterized in that: The main valve body further includes a support portion, which protrudes upward from the upper end of the first portion. The thin-walled section is located on the outer periphery of the support portion, and at least a portion of the support portion abuts against the thin-walled section. The end face diameter of the shoulder of the stirring head is defined as Φd. Along the axial direction of the support portion, the height of the portion abutting against the thin-walled section is defined as h. Along the radial direction of the support portion, the thickness of the support portion is defined as T. The three satisfy the following relationship: T≥h, h>0.25×Φd. The main valve body also includes a condensing groove. Along the height direction of the electric valve, the condensing groove is located further away from the support portion than the first portion. The condensing groove is connected to the first portion. A second plane is defined, which is perpendicular to the central axis of the first portion. At least a portion of the projection of the condensing groove onto the second plane is tangent to the projection of the first portion onto the second plane.

2. The electric valve according to claim 1, characterized in that: The support portion further includes an arc surface and an inner circumferential surface. One end of the arc surface is connected to the inner circumferential surface, and the other end of the arc surface is connected to the upper end surface of the first portion. A first plane is defined as a plane passing through the central axis of the support portion. The arc radius of the arc surface projected onto the first plane is defined as R, where R > 1 mm.

3. The electric valve according to claim 2, characterized in that: The main valve body also includes a stepped portion, which is located further away from the support portion than the first portion along the height direction of the electric valve, and the arc groove is formed by recessing inward from the side wall of the stepped portion. The arc-shaped groove includes an arc segment and a planar segment. The arc segment is located on both sides of the planar segment. One side of the arc segment is connected to the side wall of the step portion, and the other side of the arc segment is connected to the planar segment. Along the radial direction of the first portion, the planar segment is located further away from the side wall of the step portion than the arc segment. The projection of the planar segment on the second plane is tangent to the projection of the first portion on the plane. The width of the planar segment is defined as W, where W≥Φd+1.

4. The electric valve according to any one of claims 1-3, characterized in that: The axial height of the first part is defined as H, where H ≥ 0.5 × (Φd + 1), the end face diameter of the shoulder is defined as Φd ≥ 5 mm, the thickness of the thin-walled section is defined as B, where B ≤ 5 mm, and both the gearbox and the main valve body are made of aluminum.

5. The electric valve according to claim 4, characterized in that: The gearbox further includes a first protrusion. Along the radial direction of the gearbox, the first protrusion protrudes outward from the outer peripheral surface of the thin-walled section. Along the axial direction of the gearbox, one end face of the first protrusion is flush with the free end face of the thin-walled section, and the other end face of the first protrusion forms a step with the outer peripheral surface of the thin-walled section. The main valve body also includes a second protrusion. Along the radial direction of the first part, the second protrusion protrudes outward from the outer peripheral surface of the first part. Along the axial direction of the first part, one end face of the second protrusion is flush with the upper end face of the first part, and the other end face of the second protrusion forms a step with the outer peripheral surface of the first part.

6. The electric valve according to claim 5, characterized in that: Along the radial direction of the gearbox, the thickness of the first protrusion is defined as b1, where b1 ≥ 0.2 mm. Along the axial direction of the gearbox, the length of the first protrusion is defined as L1, where L1 satisfies: 0.25 × (Φd + 1) ≤ L1 ≤ 0.5 × (Φd + 1). Along the radial direction of the first protrusion, the thickness of the second protrusion is defined as b2, where b2 ≥ 0.2 mm. Along the axial direction of the first protrusion, the length of the second protrusion is defined as L2, where L2 satisfies: 0.25 × (Φd + 1) ≤ L2 ≤ 0.5 × (Φd + 1). The protrusion thickness b1 of the first protrusion and the protrusion thickness b2 of the second protrusion satisfy the relationship: b1=b2.

7. The electric valve according to any one of claims 1-3 and 5-6, characterized in that: The electric valve further includes a transmission mechanism, wherein the gearbox and the main valve body are assembled to form a first cavity, and the transmission mechanism is located in the first cavity; The transmission mechanism includes a first internal gear ring and a second internal gear ring. The first internal gear ring is connected and fixed to the gearbox. Along the axial direction of the gearbox, the first internal gear ring and the second internal gear ring are arranged facing each other. The second internal gear ring can rotate circumferentially relative to the first internal gear ring. Along the radial direction of the gearbox, the assembly gap between the outer edge of the second internal gear ring and the inner circumferential surface of the thin-walled section is 1mm to 1.5mm.

8. The electric valve according to claim 4, characterized in that: The electric valve further includes a transmission mechanism, wherein the gearbox and the main valve body are assembled to form a first cavity, and the transmission mechanism is located in the first cavity; The transmission mechanism includes a first internal gear ring and a second internal gear ring. The first internal gear ring is connected and fixed to the gearbox. Along the axial direction of the gearbox, the first internal gear ring and the second internal gear ring are arranged facing each other. The second internal gear ring can rotate circumferentially relative to the first internal gear ring. Along the radial direction of the gearbox, the assembly gap between the outer edge of the second internal gear ring and the inner circumferential surface of the thin-walled section is 1mm to 1.5mm.

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