Preparation method of electronic expansion valve

Abstract

The invention provides a preparation method of an electronic expansion valve. The electronic expansion valve comprises a rotor part, a valve rod assembly, a nut assembly, a valve body, a coil part and a cover body. The rotor component is located on the outer side of the valve rod assembly and connected with the valve rod assembly, the valve rod assembly is in threaded fit with the nut assembly, and part of the valve rod assembly is located in the cover body; the valve body and the cover body are made of different materials. The method comprises the following steps that the rotor component, the valve rod assembly, the nut assembly and the valve body are assembled; the cover body is sleeved with the rotor component, the lower end of the cover body is inserted into the valve body, and an annular groove is formed between the valve body and the cover body; welding flux is placed in the annular groove and matched with at least one of the cover body and the valve body in a face abutting mode in the radial direction; laser irradiates the welding flux to weld the cover body and the valve body. In the scheme, the cover body and the valve body can be made of different materials, so that the cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of valve processing, and in particular to a method for preparing an electronic expansion valve. Background Art

[0002] The electronic expansion valve includes a cover body and a valve body, which together form a cavity. The drive coil, rotor assembly, valve stem, etc. of the electronic expansion valve are all arranged in the cavity. The cover body plays a protective role, so the cover body is generally made of high-strength stainless steel. In order to facilitate connection, the valve body is also made of the same stainless steel as the cover body. Therefore, the cost of the electronic expansion valve is relatively high. Summary of the invention

[0003] The purpose of the present application is to provide a method for preparing an electronic expansion valve, so that the valve body can be made of a material different from that of the cover body, such as aluminum alloy, to reduce costs.

[0004] The application provides a method for preparing an electronic expansion valve, the electronic expansion valve comprising a rotor component, a valve stem assembly, a nut assembly, a valve body, a coil component and a cover body; the rotor component is located outside the valve stem assembly and connected to the valve stem assembly, the valve stem assembly and the nut assembly are threadedly matched, and part of the valve stem assembly is located in the cover body; the valve body and the cover body are made of different materials, and the method comprises the following steps:

[0005] Assemble the rotor component, the valve stem assembly, the nut assembly and the valve body; cover the rotor component, insert the lower end of the cover into the valve body, and form an annular groove between the valve body and the cover;

[0006] Put the solder into the annular groove and make a surface contact fit with at least one of the cover body and the valve body in the radial direction;

[0007] The laser irradiates the solder to weld the cover body and the valve body.

[0008] In this application, an annular groove is formed to accommodate solder so that the cover body and the valve body are welded and fixed by laser welding. The cover body and the valve body can be made of different materials, thereby making it easy to achieve high-performance materials while reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the structure of the electromagnetic expansion valve in the embodiment of the present application;

[0010] Figure 2 for Figure 1 A cross-sectional view of the electromagnetic expansion valve along the AA direction;

[0011] Figure 3 for Figure 2Schematic diagram of the assembly of the middle valve body and the lower end of the cover body;

[0012] Figure 4 for Figure 3 Enlarged view of the B area;

[0013] Figure 5 for Figure 4 An enlarged view of the gap between the middle cover and the valve body;

[0014] Figure 6 for Figure 1 Schematic diagram of the coil components.

[0015] Figure 1-6 The reference numerals in the drawings are described as follows:

[0016] 1 Electronic expansion valve 110 Second sealing ring 11 Cover 111 Sealing part 12 Valve body 112 solder 13 Valve core seat 12a Ring-shaped protrusion 14 Cover 12b Step 15 Fixed ring 12b1 Step side wall 16 Rotor parts 12b1-1 First wall 17 Valve stem assembly 12b1-2 Second wall 18 Nut assembly 12b2 Step surface 19 First sealing ring 11a Ring 12d Through hole part 12c Upper surface DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] Please refer to Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of the electromagnetic expansion valve in the embodiment of the present application; Figure 2 for Figure 1 Cross-sectional view of the electromagnetic expansion valve along the AA direction.

[0019] Figure 2 The electronic expansion valve 1 shown comprises a rotor component 16, a valve stem assembly 17, a nut assembly 18, a valve body 12, a cover body 14, a valve core seat 13 and a coil component 11. The valve core seat 13 is provided with a valve port, a portion of the valve stem assembly 17 is located in the valve core seat 13, a portion of the valve stem assembly 13 is located in the cover body 14, the nut assembly 18 and the rotor component 16 are located in the cover body 14, in addition, the internal thread of the nut assembly 18 and the external thread of the valve stem assembly 17 are matched, the coil component 11 is sleeved on the outside of the rotor component 16, the rotor component 16 is located on the outside of the valve stem assembly 17 and connected to the valve stem assembly 17, when the coil component 11 is energized, it can drive the rotor component 16 to rotate, and then drive the valve stem assembly 17 to rotate, because the valve stem assembly 17 and the nut assembly 18 are threadedly matched, when the valve stem assembly 17 rotates relative to the nut assembly 18, it moves axially at the same time, thereby blocking or opening the valve port opened by the valve core seat 13, so as to achieve the purpose of switching the electronic expansion valve 1 and adjusting the opening of the electronic expansion valve 1.

[0020] like Figure 2As shown, the electronic expansion valve 1 also includes an annular fixing ring 15, and the fixing ring 15 is fixed to the valve body 12. The fixing ring 15 can be fixed in the valve body 12 by riveting or pressing, and the nut assembly 18 can be fixed to the fixing ring 15. In this embodiment, the nut assembly 18 is provided with an annular connecting plate, which can be fixed by riveting the fixing ring 15. It can be seen that the nut assembly 18 can also be fixed directly to the valve body 12. In this embodiment, the cover body 14 is covered with a rotor component 16, and the end of the cover body 14 away from the valve body 12 is defined as the upper end, and the opposite end is defined as the lower end. The upper and lower directions are defined in the axial direction with this reference. The cover body 14 in this embodiment is a cover-like structure with a closed top and an open bottom. The cover is arranged on the valve body 12, which can isolate the internal parts from the outside to prevent damage such as bumps. The cover body 14 and the valve body 12 can be made of different materials. For example, the cover body 14 can be made of stainless steel, and the valve body 12 can be made of aluminum alloy. The valve body 12 can also be made of other materials. The cover body 14 and the valve body 12 arranged in this way have different materials. The combination of the two has excellent corrosion resistance and light weight, and the cost of aluminum alloy is relatively low, so the cost can be reduced.

[0021] See also Figure 3 and Figure 4 , Figure 3 for Figure 2 A schematic diagram of the assembly of the middle valve body 12 and the lower end of the cover body 14; Figure 4 for Figure 3 Magnified view of area B.

[0022] like Figure 3 As shown, the valve body 12 has a through hole portion 12d, which penetrates the valve body 12 in the axial direction, and the valve core seat 13, the fixing ring 5, etc. are partially located in the through hole portion 12d. In this embodiment, the sleeve 14 and the valve body 12 are assembled to form an annular groove. Specifically, as shown in FIG. Figure 3 As shown, an annular protrusion 12a is provided on the upper end surface 12c of the valve body 12. The annular protrusion 12a and the valve body 12 are directly formed as one piece, or the relatively straight upper end surface of the valve body 12 is machined and formed. In this case, it is equivalent to forming an annular step groove on the upper end of the valve body 12. The annular protrusion 12a and the part of the upper end surface 12c located inside the annular protrusion 12a form the step groove. In addition, the inner wall of the valve body 12 is also provided with an annular step portion 12b. The step portion 12b includes a side wall portion 12b1 and a step surface 12b2. The side wall portion 12b1 extends in the axial direction, and the step surface 12b2 is arranged upward. When assembled, as shown in FIG. Figure 4 As shown, the lower end surface of the cover body 14 and the step surface 12b2 of the valve body 12 are axially abutted, and the lower end surface of the cover body 14 can be supported on the step surface 12b2. At this time, the outer wall of the cover body 14 and the step groove are surrounded to form an annular groove.

[0023] On this basis, this embodiment provides a method for processing an electronic expansion valve 1 by laser welding, and the processing method is specifically as follows:

[0024] Step S1, assemble the rotor component 16, the nut assembly 18, the valve stem assembly 17 and the valve body 12, and cover the rotor component 16, and support the lower end surface of the cover 14 on the step surface 12b2. The assembly steps here are not limited to this. After the rotor component 16, the nut assembly 18, the valve stem assembly 17 and the cover 14 are assembled, they can be inserted into the valve body 12 together. When the fixing ring 15 is set, the fixing ring 15 can be fixed to the valve body 12 first, for example, by riveting, pressing, etc., and then the above-mentioned nut assembly 18 is installed. The nut assembly 18 and the fixing ring 15 can be fixed by riveting or other fixing methods. In addition, the aforementioned valve core part 13 can be pre-inserted into the valve body 12, and then the above-mentioned rotor component 16, nut assembly 18, valve stem assembly 12, cover 14, etc. are installed.

[0025] Step S2, placing the solder 112 into the annular groove between the annular protrusion 12a and the cover body 14, so that the solder 112 and at least one of the valve body 12 and the sleeve 14 are in surface contact, specifically, the inner surface of the solder 112 is in surface contact with the outer wall of the sleeve 14, or the outer surface of the solder 112 is in surface contact with the inner wall of the annular protrusion 12a. Surface contact means surface contact, which can be just contact or have a certain abutment force;

[0026] Step S3, laser irradiates the solder 112 to perform laser welding to weld the cover body 14 and the valve body 12. The laser beam can be emitted by a laser device, and the laser device also includes a tooling for clamping the assembled cover body 14, valve body 12 and other components, and the tooling has, for example, pneumatic clamps or a three-jaw chuck, etc., to clamp and position the components to be welded, and then perform the laser welding operation.

[0027] After the laser welding is completed, the coil component 11 can be sleeved on the outer periphery of the cover body 14 to form the electronic expansion valve 1.

[0028] Figure 4In this embodiment, the solder 112 is a flat structure, that is, the cross section of the solder 112 is rectangular or square. When the cross section of the solder 112 is rectangular, its long side extends axially and its short side extends radially, so that the inner surface of its long side can face the sleeve 1, and the outer surface can face the annular protrusion 12a. In addition, the annular groove has a width a in the radial direction, and the size of the solder 112 in the radial direction is equal to the width a. The equality mentioned here is roughly equal and can be slightly deviated. After the solder 112 is inserted into the annular groove, it can abut against at least one of the outer wall of the cover body 14 and the inner wall of the annular protrusion 12a. When it is not abutted, it can also be set to a very small gap. In this way, after the solder 112 is installed in the annular groove, the position is relatively fixed.

[0029] Laser welding is a process of using a laser device to emit a laser beam to the welding position to melt the solder 112 to achieve the purpose of welding. Specifically, in this embodiment, the laser device needs to emit a laser beam to the solder 112 in sequence along the circumferential direction. That is to say, the solder 112 is not irradiated with laser energy as a whole at the same time. If the position of the solder 112 is not fixed, the part that is first irradiated with the laser may have melted, and the remaining parts may shift accordingly, causing the solder 112 at the subsequent laser beam irradiation part to become thinner or accumulate and thicken, and there is a problem of uneven welding along the circumference of the solder 112. In this embodiment, the solder 112 is set to abut against at least one of the cover body 14 and the annular protrusion 12a, so that the position of the solder 112 is relatively fixed, and it is not easy to shift or deform during the implementation of laser welding, which is conducive to ensuring the reliability of laser welding. It can be seen that the solder 112 is set to a flat structure to distinguish it from the conventional solder with a circular cross-section. If the circular solder is set to abut against the annular protrusion 12a and the cover body 14, it is easy to deform, which is not conducive to the uniformity of laser welding. The flat structure solder 112 can have a larger area to fit and abut against the annular protrusion 12a or the sleeve 14, and has stronger stability.

[0030] You can continue to refer to Figure 5 , Figure 5 for Figure 4 An enlarged view of the gap between the middle cover body 14 and the valve body 12.

[0031] In this embodiment, if Figure 4As shown, the stepped side wall 12b1 of the valve body 12 includes a first wall portion 12b1-1 and a second wall portion 12b1-2 distributed axially. The first wall portion 12b1-1 and the second wall portion 12b1-2 are annular walls, specifically circular annular walls. Among them, the second wall portion 12b1-2 is closer to the stepped surface 12b2 and is connected to the stepped surface 12b2, and their axial cross-sections form an L shape. Among them, the first wall portion 12b1-1 has a diameter R1, the second wall portion 12b1-2 has a diameter R2, and the outer wall of the cover 14 has a diameter R3, and it satisfies: R2 < R3 < R1. With such a setting, when the cover 14 is inserted axially into the valve body 12, the cover 14 and the second wall portion 12b1-2 are in interference fit, and the interference amount is d, while a gap 1a is formed radially between the cover 14 and the first wall portion 12b1-1, and the width dimension of the gap 1a in the radial direction is c.

[0032] With such a setting, during laser welding, after the solder 112 melts, it is located in the annular groove, and part of it can flow into the gap 1a, so that the welding area between the valve body 12 and the cover 14 is increased, and the welding strength can be correspondingly improved. In addition, in this embodiment, the second wall portion 12b1-2 of the valve body 12 and the cover 14 are in interference fit. During laser welding, the cover 14 and the valve body 12 can be positioned, which is beneficial to the stable progress of welding. The connection relationship between the cover 14 and the valve body 12 after welding is a combination of interference fit and welding, and the connection is reliable. The first wall portion 12b1-1 and the second wall portion 12b1-2 can be transitioned by an inclined surface to reduce stress concentration and facilitate the infiltration of solder.

[0033] In this embodiment, the width c of the gap 1a between the first wall portion 12b1-1 of the valve body 12 and the cover 14 can be set to 0.1 mm to 0.3 mm. During laser welding, the laser heating area is small and concentrated, and the welding time is short, usually only a few seconds. At this time, the cooling speed of the liquid solder is relatively fast. In order to ensure that the solder can flow into the gap 1a as soon as possible before cooling, the width c of the gap 1a can be set to be relatively large, such as within the range of 0.1 mm to 0.3 mm as described above.

[0034] In addition, in this embodiment, the wall thickness of the cover 14 is defined as t, as Figure 4As shown, the axial dimension of the first wall portion 12b1-1 is length L1, and the axial dimension of the second wall portion 12b1-2 is length L2. The length L1 of the first wall portion 12b1-1 can satisfy: L1 = (1 ~ 3) t. The length of the first wall portion 12b1-1 is related to the axial length of the gap 1a, and is set to (1 ~ 3) t, which is conducive to ensuring the welding effect. It can be seen that the wall thickness t of the cover body 14 is also related to the ability to withstand interference fit. Here it is set to L1 = (1 ~ 3) t, and the length is relatively short. Then the length L2 of the second wall portion 12b1-2 can be set relatively longer. In this way, under the premise of ensuring welding reliability, it is conducive to ensuring the connection reliability of interference fit.

[0035] like Figure 4 As shown, the annular groove has a depth H, which is also the height of the annular protrusion 12a in the axial direction. The depth H of the annular groove is set to be less than the height b of the solder 112 in the axial direction. The solder 112 protrudes from the annular groove in the axial direction. In this way, the solder 112 after melting can fill the annular groove to ensure the welding needs. Of course, the height of the solder 112 should not be too high to avoid wasting the solder and flowing to unnecessary positions. For example, the depth H and height b of the annular groove in this embodiment meet: H = (0.6 ~ 0.8) b.

[0036] In detail, when laser welding is performed in the above processing method, the following operations can be performed:

[0037] A laser beam is emitted to the position of the solder 112 by a laser device, wherein the laser beam can be incident at an angle of 10° to 60° with the vertical plane, the defocus amount is -5mm to -30mm, and the spot is larger than the radial size of the solder 112. The laser power can be set to 1500W to 4000W, and the welding speed can be 4mm to 10mm / s, which is the speed at which the laser beam runs circumferentially along the solder 112. Of course, the above laser welding parameters can also be adjusted according to actual conditions.

[0038] It should be noted that, in this embodiment, before laser welding, the cover body 14 and the valve body 12 can also be cleaned with an organic solvent. Specifically, the cover body 14 and the valve body 12 can be cleaned before assembly, or the cover body 14 and the valve body 12 can be cleaned at the same time after assembly. The organic solvent is, for example, ethanol, acetone, CCl4, etc. The cleaning method can be ultrasonic, which is used to remove oil and impurities on the surface of the parts to ensure the subsequent welding effect. After cleaning, the cover body 14 and the valve body 12 can be further immersed in a 10% NaOH and 15% HNO3 solution to remove the oxide film, and then cleaned with anhydrous ethanol and dried, and then laser welding can be performed.

[0039] In this embodiment, the cover body 14 and the valve body 12 are made of different materials. The valve body 12 can be made of a material with low cost and light material such as aluminum alloy, so that the cost and weight of the manufactured electronic expansion valve 1 can be reduced. To achieve this purpose, laser welding is used to weld the cover body 14 and the valve body 12, and an annular groove is provided to accommodate flat solder for welding, so that laser welding can be implemented. Laser welding has the advantages of fast heating speed, high efficiency, concentrated energy, minimal heat impact, small deformation of parts, clean joints, and easy automation.

[0040] In addition, if Figure 1 As shown, the outer peripheries of the valve core seat 13 and the valve body 12 are respectively provided with a second sealing ring 110 and a first sealing ring 19, and a sealing portion 111 is also provided between the valve body 12 and the coil component 11, all of which play a sealing role. Figure 6 , Figure 6 for Figure 1 Schematic diagram of the middle coil component, the lower end face of the coil component 11 is provided with an annular sleeve 11a extending in the axial direction, the inner wall of the annular sleeve 11a is provided with a step surface, the sealing portion 111 can abut between the step surface of the annular sleeve 11a and the valve body 12, specifically, can abut between the step surface and the annular protrusion 12a, so as to achieve a better sealing effect.

[0041] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing an electronic expansion valve, characterized in that: The electronic expansion valve comprises a rotor component, a valve stem assembly, a nut assembly, a valve body, a coil component and a cover body; the rotor component is located outside the valve stem assembly and connected to the valve stem assembly, the valve stem assembly and the nut assembly are threadedly matched, and part of the valve stem assembly is located in the cover body; the valve body and the cover body are made of different materials, and the method comprises the following steps: Assemble the rotor component, the valve stem assembly, the nut assembly and the valve body; cover the rotor component, insert the lower end of the cover into the valve body, and form an annular groove between the valve body and the cover; Put the solder into the annular groove and make a surface contact fit with at least one of the cover body and the valve body in the radial direction; The laser irradiates the solder to weld the cover body and the valve body.

2. The method for preparing an electronic expansion valve according to claim 1, characterized in that: Prepare solder: shape the annular solder so that the cross section of the solder is rectangular or square; abut the inner surface of the solder against the sleeve, and / or abut the outer surface of the solder against the inner wall of the annular groove.

3. The method for preparing an electronic expansion valve according to claim 1, characterized in that: A first wall portion and a second wall portion are formed on the inner wall of the valve body, and the diameter of the first wall portion is larger than the diameter of the second wall portion, so that the cover body and the second wall portion have an interference fit, and a gap is formed between the cover body and the first wall portion, and the solder flows into the gap after melting.

4. The method for preparing an electronic expansion valve according to claim 3, characterized in that: The width of the gap in the radial direction is 0.1 mm to 0.3 mm.

5. The method for preparing an electronic expansion valve according to claim 3, characterized in that: The wall thickness of the cover body is t, and the length L1 of the first wall portion along the axial direction satisfies: L1 = (1-3) t.

6. The method for preparing an electronic expansion valve according to any one of claims 1 to 5, characterized in that: The process parameters of laser welding include at least one of the following: The laser beam is incident at an angle of 10° to 60° with the vertical plane; The defocus range is -5mm to -30mm; The spot of the laser beam is larger than the radial size of the solder; The power of the laser beam is 1500w~4000w; The welding speed is 4mm / s~10mm / s.

7. The method for preparing an electronic expansion valve according to any one of claims 1 to 5, characterized in that: Before laser welding, the cover body and the valve body are cleaned with an organic solvent. After cleaning, the cover body and the valve body are immersed in a 10% NaOH and 15% HNO3 solution to remove the oxide film, and then cleaned with anhydrous ethanol and dried.

8. The method for preparing an electronic expansion valve according to any one of claims 1 to 5, characterized in that: The valve body is made of aluminum alloy, and the cover body is made of stainless steel.

Images