Assembly method of electronic expansion valve and electronic expansion valve

Abstract

The present invention discloses an assembly method for an electronic expansion valve and an electronic expansion valve. The assembly method includes assembling a valve needle assembly, including: placing a valve needle sleeve in a screw hole of a screw, determining a first distance L1 between the upper end face of the valve needle sleeve and the upper end face of the screw when the second limit face of the valve needle sleeve abuts the first limit face of the screw; removing the valve needle sleeve, pre-pressing the valve needle sleeve onto the valve needle, and then assembling it with a rotor assembly to obtain a rotor assembly; assembling the rotor assembly with the valve body assembly of the electronic expansion valve, and rotating the screw relative to the valve body assembly to a bottom dead center position, and determining a second distance L2 between the upper end face of the valve needle sleeve and the upper end face of the screw in this state; after determining the second distance L2, separating the rotor assembly from the valve body assembly, and then press-fitting the valve needle sleeve so that the press-fitting depth of the valve needle sleeve downward relative to the valve needle is H, where H = L1-L2-△, where △ is the length corresponding to the valve opening pulse. This assembly method can reduce the impact of component processing errors on the accuracy of valve opening pulse control.

Description

Technical Field

[0001] The present invention relates to the technical field of valve assembly, and in particular to an assembling method of an electronic expansion valve and the electronic expansion valve. Background Art

[0002] The operating principle of the direct-acting electronic expansion valve is: the coil drives the rotor to rotate circumferentially, and the screw fixed relative to the rotor rotates accordingly. The screw and the nut fixed relative to the valve body are threaded together. Under the action of the threaded transmission, the screw also moves axially along the valve body to drive the valve needle close to or away from the valve port, so as to realize the flow regulation of the refrigerant.

[0003] Generally speaking, an electronic expansion valve has a corresponding length of valve opening pulse, that is, the valve needle has a valve opening stroke from the bottom dead point position of the closed valve to the opening process of the electronic expansion valve. Taking zero flow when the valve is closed as an example, when the valve is opened, the valve flow is still zero during the valve opening stroke stage. After this valve opening stroke, the valve flow begins to change when the valve needle continues to move in the valve opening direction.

[0004] The existing assembly method of electronic expansion valves has a valve opening pulse control accuracy that is related to the processing errors of related components or the assembly tooling, which is not conducive to ensuring the consistency of the product's valve opening pulse.

[0005] In view of this, how to improve the assembly method of the existing electronic expansion valve and reduce the impact of processing errors of components on the consistency of valve opening pulses is a technical problem that technical personnel in this field currently need to solve. Summary of the Invention

[0006] The purpose of the present invention is to provide an assembly method for an electronic expansion valve and an electronic expansion valve, wherein the assembly method can reduce the influence of the processing errors of components on the control accuracy of the valve opening pulse and can effectively improve the consistency of the product valve opening pulse.

[0007] To solve the above technical problems, an embodiment of the present invention provides an assembly method of an electronic expansion valve, wherein the electronic expansion valve comprises a rotor assembly and a valve needle, wherein the rotor assembly comprises a rotor and a screw, wherein the screw is fixedly connected to the rotor and has a first limiting surface; the valve needle assembly comprises a valve needle and a valve needle sleeve, wherein the valve needle sleeve has a second limiting surface, wherein the first limiting surface is used to support the second limiting surface;

[0008] The assembly method includes assembling the valve needle assembly, and the assembly of the valve needle assembly includes the following steps:

[0009] Place the valve needle sleeve in the screw hole of the screw, and determine a first distance L1 between the upper end surface of the valve needle sleeve and the upper end surface of the screw when the second limit surface of the valve needle sleeve abuts against the first limit surface of the screw;

[0010] Then, the valve needle sleeve is removed and pre-pressed onto the valve needle. The pre-pressed valve needle, the valve needle sleeve and the rotor assembly are assembled to obtain a rotor assembly. The rotor assembly is assembled with the valve body of the electronic expansion valve, and the screw rod is rotated relative to the valve body to the bottom dead center position. In this state, a second distance L2 between the upper end surface of the valve needle sleeve and the upper end surface of the screw rod is determined.

[0011] After determining the second distance L2, the rotor assembly and the valve body are disassembled, and then the valve needle sleeve is press-fitted so that the pressing depth of the valve needle sleeve relative to the valve needle is H, H = L1-L2-△, where △ is the length corresponding to the valve opening pulse.

[0012] In the above-mentioned method for assembling the electronic expansion valve, the method for determining the first distance L1 is as follows:

[0013] Place the valve needle sleeve in the screw hole of the screw, and make the second limit surface of the valve needle sleeve abut against the first limit surface of the screw, and measure the distance between the upper end surface of the valve needle sleeve and the upper end surface of the screw.

[0014] In the above-mentioned method for assembling the electronic expansion valve, the second limiting surface is the lower end surface of the valve needle sleeve, and the method for determining the first distance L1 is as follows:

[0015] The distance D1 between the first limiting surface of the screw rod and the upper end surface of the screw rod is measured, and the length D2 of the valve needle sleeve is measured. The first distance L1 = D1 - D2.

[0016] In the above-mentioned method for assembling the electronic expansion valve, the method for determining the first distance L1 is as follows:

[0017] The processing distance between the first limiting surface of the screw rod and the upper end surface of the screw rod is D1', the processing length of the valve needle sleeve is D2', and the first distance L1 = D1'-D2'.

[0018] According to the above-mentioned assembly method of the electronic expansion valve, the flow rate of the electronic expansion valve is zero when it is in the fully closed state, and the length Δ corresponding to the valve opening pulse is a positive number.

[0019] According to the assembly method of the electronic expansion valve as described above, after the valve needle sleeve is pressed into place, the rotor assembly is assembled with the valve body, and the screw rod is rotated to the bottom dead center position. The third distance L3 between the upper end surface of the valve needle sleeve and the upper end surface of the screw rod in this state is determined. If the deviation between the third distance L3 and the target distance is greater than the set value, the valve needle sleeve is pressed downward relative to the valve needle to compensate for the deviation; the target distance is L1-△.

[0020] In the above-mentioned assembly method of the electronic expansion valve, the flow rate of the electronic expansion valve is not zero when it is in the fully closed state, and the length Δ corresponding to the valve opening pulse is a negative number.

[0021] The present invention further provides an electronic expansion valve, which is assembled by any of the above-mentioned assembling methods.

[0022] The present invention provides an assembly method for an electronic expansion valve, in which the assembly of the valve needle sleeve and the valve needle is achieved through pre-pressing and press-fitting, wherein the press-fitting depth of the valve needle sleeve relative to the valve needle is determined by measuring the relative positions of related components, thereby reducing the influence of component processing errors on the press-fitting depth and improving the consistency of the product valve opening pulse.

[0023] The electronic expansion valve obtained by adopting the above-mentioned assembly method also has corresponding technical effects and can ensure the accuracy of valve opening pulse control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A partial cross-sectional schematic diagram of an electronic expansion valve provided in an embodiment of the present invention;

[0025] Figure 2 A schematic cross-sectional view of an electronic expansion valve provided in an embodiment of the present invention;

[0026] Figure 3 for Figure 2 A schematic cross-sectional view of the middle rotor assembly;

[0027] Figure 4 A schematic diagram of the first step of the assembly method of the electronic expansion valve provided by an embodiment of the present invention;

[0028] Figure 5 A schematic diagram of the second step of the assembly method of the electronic expansion valve provided by an embodiment of the present invention;

[0029] Figure 6 A schematic diagram of the third step of the assembly method of the electronic expansion valve provided in an embodiment of the present invention;

[0030] Figure 7 is a cross-sectional schematic diagram of an electronic expansion valve with zero flow in a fully closed state in a specific embodiment;

[0031] Figure 8 Schematic cross-section of an electronic expansion valve with a non-zero flow rate in a fully closed state in a specific embodiment.

[0032] Description of reference numerals:

[0033] Valve body 11, valve port 111, nut member 12, internal thread structure 121, limiting protrusion 122, rotor 13, magnet 131, limiting boss 1311, insert 132, screw 14, screw hole 141, first hole section 1411, second hole section 1412, first limiting surface 1413, external thread structure 144, valve needle 15, valve needle sleeve 16, second limiting surface 162;

[0034] The valve body consists of 1A and the rotor assembly is 1B;

[0035] Guide sleeve 21 , guide hole 211 , support seat 22 , tooling valve port 221 , pressure head 23 . DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] Please refer to Figure 1 and Figure 2 , Figure 1 and Figure 2 The cross-sectional views of the electronic expansion valve at different positions are shown respectively.

[0038] In this embodiment, the electronic expansion valve includes a valve body 11, a nut component 12, a rotor 13, a screw 14, and a valve needle 15. The nut component 12 is fixedly connected to the valve body 11. The rotor 13 includes a magnet 131 and an insert 132. The rotor 13 is fixedly connected to the screw 14 via its insert 132. The insert 132 specifically surrounds the screw 14 and is fixedly connected to the screw 14. The two can be fixed by welding. The screw 14 and the valve needle 15 are relatively movable in the axial direction. The screw 14 is threadedly connected to the nut component 12. Specifically, the screw 14 has an external thread structure 144, and the nut component 12 has an internal thread structure 121. The screw 14 can be axially displaced relative to the nut component 12 through threaded engagement. The rotor 13 and screw 14 fixed together are generally referred to as a rotor assembly.

[0039] During operation, the rotor 13 is driven to rotate circumferentially through the coil (not shown in the figure), driving the screw rod 14 to rotate together. Under the action of the threaded connection between the screw rod 14 and the nut component 12, the screw rod 14 drives the valve needle 15 along the axial direction of the valve body 11 to approach or move away from the valve port 111 to achieve flow regulation of the refrigerant.

[0040] It is understood that since the screw rod 14 and the rotor 13 are fixed, when the rotor 13 moves axially, it moves with the screw rod 14. When the two move axially downward (near the valve port 111) to the lower limit position, the valve needle 15 cooperates with the valve port 111. This position is also called the zero position. In order to ensure the flow consistency of the electronic expansion valve, this zero position control is crucial. Currently, this zero position is ensured by a limiting structure. Specifically, a limiting protrusion 122 is provided on the nut component 12, and a limiting boss 1311 is provided on the lower end face of the magnet 131 of the rotor 13. The limiting boss 1311 protrudes downward from the lower end face of the magnet 131. When the rotor 13 and the screw rod 14 move axially downward until the limiting boss 1311 and the limiting protrusion 122 are circumferentially abutted, the rotor 13 and the screw rod 14 cannot move further downward, thereby achieving zero position control.

[0041] Obviously, when the valve needle 15 is at zero position, the flow rate of the electronic expansion valve is minimum. Electronic expansion valves generally have a corresponding length of valve opening pulse. That is, the valve needle 15 has a valve opening stroke during the process of opening from zero position (bottom dead center). This valve opening stroke is achieved by the axial limit abutment between the valve needle 15 and the screw rod 14.

[0042] In this embodiment, the valve needle 15 of the electronic expansion valve is specifically connected to the screw rod in the axial limit position through the valve needle sleeve 16. The valve needle 15, the valve needle sleeve 16 and other related connecting parts can be referred to as the valve needle component. Figure 3 As shown, Figure 3 for Figure 2 A cross-sectional diagram of the middle rotor assembly, where the assembled structure of the rotor assembly and the valve needle is referred to as the rotor assembly 1B.

[0043] Among them, the screw rod 14 has a screw rod hole 141 for part of the valve needle 15 to pass through, and the screw rod hole 141 has a first hole section 1411 and a second hole section 1412. The first hole section 1411 is located above the second hole section 1412, and the aperture of the first hole section 1411 is larger than the aperture of the second hole section 1412, so that a first limiting surface 1413 facing away from the valve port 111 is formed at the connection between the first hole section 1411 and the second hole section 1412.

[0044] The valve needle sleeve 16 is positioned over the upper end of the valve needle 15 and is fixedly connected to the valve needle 15. The valve needle 15 is partially located within the screw hole 141 of the screw rod 14 and abuts against the screw rod 14 at its upper axial limit position through the valve needle sleeve 16. Specifically, the lower end surface of the valve needle sleeve 16 forms a second limit surface 162, which is supported by the first limit surface 1413 of the screw rod 14. The valve needle 15 is axially movable relative to the screw rod 14.

[0045] Combine Figure 2 and Figure 3 , Figure 2The electronic expansion valve is in the zero position, that is, the bottom dead center position, and the valve needle 15 closes the valve port 111. When the valve is opened, the coil drives the rotor assembly to rotate. After the rotor assembly drives the valve needle assembly to move axially upward by the length corresponding to the valve pulse, the flow rate of the electronic expansion valve begins to change. The accuracy of the valve opening pulse is related to the connection and coordination of the screw rod 14, the valve needle assembly and the valve port 111.

[0046] This embodiment provides an assembly method for an electronic expansion valve, which can reduce the impact of machining errors of related components on the valve opening pulse control accuracy and effectively improve the valve opening pulse consistency of the electronic expansion valve.

[0047] In this embodiment, the assembly method of the electronic expansion valve includes the assembly of the valve needle component, specifically the relative position relationship between the valve needle sleeve 16 and the valve needle 15 in the axial direction.

[0048] Please refer to Figures 4 to 6 , Figure 4 A schematic diagram of the first step of the assembly method of the electronic expansion valve provided by an embodiment of the present invention; Figure 5 A schematic diagram of the second step of the assembly method of the electronic expansion valve provided by an embodiment of the present invention; Figure 6 This is a schematic diagram of the third step of the assembly method of the electronic expansion valve provided by an embodiment of the present invention.

[0049] The assembly method comprises the following steps:

[0050] When the rotor assembly has been assembled, that is, when the relative positions of the magnet 131, the insert 132 and the screw 14 are fixed, the valve needle sleeve 16 is placed in the screw hole 141 of the screw 14. The first limiting surface 1413 of the screw 14 supports the second limiting surface 162 of the valve needle sleeve 16. At this time, the first distance L1 between the upper end surface of the valve needle sleeve 16 and the upper end surface of the screw 14 is measured. Figure 4 As shown;

[0051] After that, take out the valve needle sleeve 16, pre-press the valve needle sleeve 16 onto the valve needle 15, assemble the pre-pressed valve needle 15 and the valve needle sleeve 16 with the rotor assembly to obtain the rotor assembly 1B, and assemble the rotor assembly 1B with the valve body 1A of the electronic expansion valve, as shown in FIG. Figure 5 As shown, the valve body assembly 1A includes the valve body 11, the nut component 12 fixedly connected to the valve body 11, and other structures fixed relative to the valve body 11. During assembly, the screw rod 14 is rotated relative to the nut component 12 to the bottom dead center position, i.e., the zero position, and the second distance L2 between the upper end surface of the valve needle sleeve 16 and the upper end surface of the screw rod 14 is determined in this state.

[0052] After determining the second distance L2, the rotor assembly 1B and the valve body assembly 1A are separated, and the valve needle sleeve 16 is press-fitted so that the valve needle sleeve 16 moves downward relative to the valve needle 15 to a press-fit depth of H, where H = L1 - L2 - △, where △ is the length corresponding to the valve opening pulse. Figure 6 As shown, the corresponding tooling is used when pressing the valve needle sleeve 16. It should be pointed out that the valve needle sleeve 16 can also be pre-pressed on the valve needle 15. Figure 6 The tooling shown in .

[0053] like Figure 6 As shown, the tooling for pressing the valve needle sleeve 16 includes a guide sleeve 21 and a support seat 22, which are relatively fixed. The guide sleeve 21 has a guide hole 211 for guiding the screw rod 14 of the rotor assembly 1B downward, and the support seat 22 has a tooling valve mouth portion 221 for simulating the valve mouth 111 of the actual product to cooperate with the valve needle 15. When the rotor assembly 1B is installed on the tooling, the valve needle 15 cooperates with the tooling valve mouth portion 221 of the support seat 22. It can be understood that the center axes of the tooling valve mouth portion 221 of the support seat 22 and the guide hole 211 of the guide sleeve 21 coincide with each other. In this mating state, the pressing head 23 is inserted into the screw rod 14 to resist the valve needle sleeve 16, and pressure is applied to the pressing head 23, so that the valve needle sleeve 16 moves downward relative to the valve needle 15 to change the axial relative position of the two. The downward pressing distance can be controlled by the pressing equipment. Specifically, the tooling may include an electric cylinder cooperating with the pressing head 23, and the pressing depth of the valve needle sleeve 16 may be controlled by controlling the downward pressure applied by the electric cylinder to the pressing head 23. Of course, the pressing head 23 may also be integrally connected to the electric pole, and the electric pole may be directly driven by the driving component to drive the pressing head 23 to press downward.

[0054] Please refer to Figure 7 , Figure 7 Schematic cross-section of an electronic expansion valve with zero flow in a fully closed state in a specific embodiment.

[0055] like Figure 7 As shown, the valve needle 15 is at the bottom dead center position. In this state, the third distance L3 between the upper end surface of the valve needle sleeve 16 and the upper end surface of the screw rod 14 is the target distance to be controlled. The target distance is L1-△. Figure 7 In the embodiment, the valve needle 15 is in the fully closed state, and the flow rate of the electronic expansion valve is zero. At this time, the length △ corresponding to the valve opening pulse is a positive number. Therefore, after assembly, at the bottom dead center position, there is an axial gap between the second limit surface of the valve needle sleeve 16 and the first limit surface 1413 of the screw rod 14. The axial gap is the length △ corresponding to the valve opening pulse. That is to say, when opening the valve, the screw rod 14 moves axially upward relative to the nut component 12 by the length △ corresponding to the valve opening pulse before driving the valve needle 15 to move upward together and start to open the valve port 111.

[0056] Combine Figure 4 、 Figure 5and Figure 7 It can be seen that after the valve needle sleeve 16 is pre-pressed relative to the valve needle 15, the pressing depth H to which the valve needle sleeve 16 needs to continue to move downward relative to the valve needle 15 = target distance - L2, that is, H = L1 - L2 - Δ.

[0057] Further, after Figure 6 As shown, after the valve needle sleeve 16 is pressed into the valve needle 15 to a pressing depth H, a calibration step is performed, that is, the pressed rotor assembly 1B is assembled with the valve body assembly 1A, and the screw rod 14 is rotated to the bottom dead center position, so that Figure 7 In the state shown, the third distance L3 is measured at this time. If the deviation between the third distance L3 and the target distance L1-Δ is greater than the set value, the valve needle sleeve 16 is press-fitted to compensate for the deviation. The set value here can be set according to product requirements.

[0058] Please refer to Figure 8 , Figure 8 Schematic cross-section of an electronic expansion valve with a non-zero flow rate in a fully closed state in a specific embodiment.

[0059] Apart from Figure 7 In addition to the electronic expansion valve shown in the figure, there are also electronic expansion valves in actual applications. Figure 8 In the type shown, when the valve needle 15 is at the bottom dead center position, the flow rate of the electronic expansion valve is not zero. At this time, the second limit surface 162 of the valve needle sleeve 16 contacts the first limit surface 1413 of the screw rod 14. The third distance L3 between the upper end surface of the valve needle sleeve 16 and the upper end surface of the screw rod 14 is the target distance that this type of electronic expansion valve needs to control. The target distance is also L1-△. However, at this time, because there is still flow when the valve is fully closed, the length △ corresponding to the valve opening pulse is a negative number. The assembly method of the valve needle assembly of this type of electronic expansion valve is the same as the above. Figure 7 The difference between the electronic expansion valve shown is that this type of electronic expansion valve does not need to be calibrated after the valve needle sleeve 16 is pressed down to the depth H.

[0060] In other embodiments, L1 in the above assembly method may be determined by other methods besides the aforementioned measurement method.

[0061] A first alternative method for determining the first distance L1 is to measure the distance D1 between the first limiting surface 1413 of the screw rod 14 and the upper end surface of the screw rod 14 and measure the length D2 of the valve needle sleeve 16 , then the first distance L1 = D1 − D2 .

[0062] In this method and the aforementioned assembly method, when assembling the valve needle assembly, the control reference of the relevant dimensions is based on the assembled rotor assembly, which is unrelated to the processing errors of the valve needle 15, valve needle sleeve 16, etc., thereby reducing the influence of the processing errors of these components on the valve opening pulse control accuracy.

[0063] A second alternative method for determining the first distance L1 is as follows: the machining distance between the first limiting surface 1413 of the screw rod 14 and the upper end surface of the screw rod 14 is D1', and the machining length of the valve needle sleeve 16 is D2'. The first distance L1 = D1' - D2'. The first distance L1 is determined by machining dimensions. Machining deviations between D1' and D2' affect the accuracy of the valve opening pulse control. This method is suitable for applications where the accuracy of the valve opening pulse control of the electronic expansion valve is not critical.

[0064] The assembly method of the valve body component 1A and the rotor assembly of the electronic expansion valve can still refer to the existing technology and will not be described in detail here. This article focuses on the assembly method of the valve needle component introduced above.

[0065] In addition to the above-mentioned assembly method of the electronic expansion valve, the present invention also provides an electronic expansion valve, the structure of which is as follows: Figure 1 、 Figure 2 、 Figure 7 and Figure 8 As shown, the electronic expansion valve is obtained by the above assembly method, and can better control the valve opening pulse accuracy.

[0066] The above describes in detail the assembly method and the electronic expansion valve provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the method and core concept of the present invention. It should be noted that for those skilled in the art, various improvements and modifications can be made to the present invention without departing from the principles of the present invention. Such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. The assembly method of the electronic expansion valve is characterized in that: The electronic expansion valve comprises a rotor assembly and a valve needle, wherein the rotor assembly comprises a rotor and a screw, wherein the screw is fixedly connected to the rotor and has a first limiting surface; the valve needle assembly comprises a valve needle and a valve needle sleeve, wherein the valve needle sleeve has a second limiting surface, wherein the first limiting surface is used to support the second limiting surface; The assembly method includes assembling the valve needle assembly, and the assembly of the valve needle assembly includes the following steps: Place the valve needle sleeve in the screw hole of the screw, and determine a first distance L1 between the upper end surface of the valve needle sleeve and the upper end surface of the screw when the second limit surface of the valve needle sleeve abuts against the first limit surface of the screw; Then, the valve needle sleeve is removed and pre-pressed onto the valve needle. The pre-pressed valve needle, the valve needle sleeve and the rotor assembly are assembled to obtain a rotor assembly. The rotor assembly is assembled with the valve body of the electronic expansion valve, and the screw rod is rotated relative to the valve body to the bottom dead center position. In this state, a second distance L2 between the upper end surface of the valve needle sleeve and the upper end surface of the screw rod is determined. After determining the second distance L2, the rotor assembly and the valve body are disassembled, and then the valve needle sleeve is press-fitted so that the pressing depth of the valve needle sleeve relative to the valve needle is H, H = L1-L2-△, where △ is the length corresponding to the valve opening pulse.

2. The assembly method of the electronic expansion valve according to claim 1, characterized in that: The method for determining the first distance L1 is as follows: Place the valve needle sleeve in the screw hole of the screw, and make the second limit surface of the valve needle sleeve abut against the first limit surface of the screw, and measure the distance between the upper end surface of the valve needle sleeve and the upper end surface of the screw.

3. The assembly method of the electronic expansion valve according to claim 1, characterized in that: The second limiting surface is the lower end surface of the valve needle sleeve. The first distance L1 is determined as follows: The distance D1 between the first limiting surface of the screw rod and the upper end surface of the screw rod is measured, and the length D2 of the valve needle sleeve is measured. The first distance L1 = D1 - D2.

4. The method for assembling an electronic expansion valve according to claim 1, characterized in that: The method for determining the first distance L1 is as follows: The processing distance between the first limiting surface of the screw rod and the upper end surface of the screw rod is D1', the processing length of the valve needle sleeve is D2', and the first distance L1 = D1'-D2'.

5. The method for assembling an electronic expansion valve according to any one of claims 1 to 4, characterized in that: When the electronic expansion valve is in a fully closed state, the flow rate is zero, and the length Δ corresponding to the valve opening pulse is a positive number.

6. The method for assembling an electronic expansion valve according to claim 5, characterized in that: After the valve needle sleeve is pressed into place, the rotor assembly is assembled with the valve body, and the screw rod is rotated to the bottom dead center position. The third distance L3 between the upper end surface of the valve needle sleeve and the upper end surface of the screw rod in this state is determined. If the deviation between the third distance L3 and the target distance is greater than the set value, the valve needle sleeve is pressed downward relative to the valve needle to compensate for the deviation; the target distance is L1-△.

7. The method for assembling an electronic expansion valve according to any one of claims 1 to 4, characterized in that: When the electronic expansion valve is in a fully closed state, the flow rate is not zero, and the length Δ corresponding to the valve opening pulse is a negative number.

8. Electronic expansion valve, characterized in that, The electronic expansion valve is an electronic expansion valve assembled by the assembly method according to any one of claims 1 to 7.

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