An electronic expansion valve

Abstract

The present invention discloses an electronic expansion valve, which includes a valve core seat and a valve needle screw rod assembly. The valve needle screw rod assembly includes a valve needle assembly and a screw rod assembly. A nut for threaded connection with the screw rod assembly is fixed on the valve core seat. The screw rod assembly is in threaded cooperation with the nut to drive the valve needle assembly to move axially, so as to adjust the refrigerant flow rate flowing through the valve port of the electronic expansion valve. A valve needle cavity is formed in the valve needle assembly, a screw rod cavity is formed between one end of the screw rod assembly close to the valve needle assembly and the nut, and the valve needle cavity is communicated with the screw rod cavity through a circulation channel. By providing the circulation channel, the pressure balance between the valve needle cavity and the screw rod cavity can be quickly achieved, thereby avoiding the liquid sealing phenomenon in the refrigerant environment in the valve needle cavity to form a closed chamber, and improving the reliability of the electronic expansion valve. Moreover, through the setting of the above circulation channel, when the electronic expansion valve moves from fully closed to fully open at the valve port, the pressure between the valve needle cavity and the screw rod cavity can also be quickly balanced.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration control, and particularly to an electronic expansion valve Background Art

[0002] The electronic expansion valve is mainly used in a variable-frequency air-conditioning system. During operation, a coil drives a rotor component to rotate, and drives a lead screw to rotate. The lead screw and a nut form a screw pair, so as to realize the axial movement of the lead screw, and drive the axial movement of a valve needle, so as to change the opening degree of a valve port, thereby adjusting the refrigerant flow rate flowing through the valve port

[0003] The valve needle of the electronic expansion valve has a valve needle cavity. When the valve needle cavity forms a closed space and the pressure is too high, the cooperation relationship between various components is prone to liquid sealing phenomenon under the action of pressure difference in the refrigerant environment, so that the elastic connection between the lead screw and the valve needle of the electronic expansion valve becomes a rigid connection, resulting in the inability of the lead screw to rotate freely, thereby reducing the working reliability of the electronic expansion valve

[0004] In view of this, how to provide an electronic expansion valve to prevent the liquid sealing phenomenon generated between the lead screw and the valve needle under the action of pressure difference in the refrigerant environment, improve the rotational flexibility of the lead screw, and thus improve the actuation reliability of the electronic expansion valve is a technical problem that those skilled in the art need to solve urgently Summary of the Invention

[0005] To solve the above technical problems, an object of the present invention is to provide an electronic expansion valve, which is characterized by including a valve core seat and a valve needle lead screw assembly. The valve needle lead screw assembly includes a valve needle assembly and a lead screw assembly. The valve core seat is fixedly connected to a nut that is in threaded cooperation with the lead screw assembly. The lead screw assembly drives the valve needle assembly to move axially through threaded cooperation with the nut, so as to adjust the refrigerant flow rate flowing through the valve port of the electronic expansion valve

[0006] The valve needle assembly forms a valve needle cavity. A lead screw cavity is formed between one end of the lead screw assembly close to the valve needle assembly and the nut. The valve needle cavity is communicated with the lead screw cavity through a flow passage

[0007] In the present invention, by providing a flow passage, the pressure balance between the valve needle cavity and the lead screw cavity can be quickly achieved through the flow passage, so as to avoid the liquid sealing phenomenon in the refrigerant environment in the valve needle cavity to form a closed chamber, and improve the reliability of the electronic expansion valve. Moreover, through the setting of the above flow passage, when the electronic expansion valve moves from fully closed to fully open at the valve port, the pressure between the valve needle cavity and the lead screw cavity can also be quickly balanced

[0008] Meanwhile, the present invention provides another electronic expansion valve, which includes a valve seat, a valve needle screw rod assembly, and a guiding component. The valve needle screw rod assembly includes a valve needle assembly and a screw rod assembly. The guiding component is fixedly connected to a nut that is in threaded cooperation with the screw rod assembly. The screw rod assembly drives the valve needle assembly to move axially through threaded cooperation with the nut to adjust the refrigerant flow rate through the valve port of the electronic expansion valve.

[0009] The guiding component has a guiding component inner cavity. The valve needle assembly is located in the guiding component inner cavity. The valve needle assembly forms a valve needle cavity. A screw rod cavity is formed between one end of the screw rod assembly close to the valve needle assembly and the nut. The valve needle cavity is communicated with the screw rod cavity through a circulation channel.

[0010] Optionally, the valve needle assembly is located in the valve core seat cavity of the valve core seat and can axially move in the valve core seat cavity. There is a first predetermined gap between the inner wall portion of the valve core seat and the outer wall portion of the valve needle assembly. The first predetermined gap is communicated with the screw rod cavity.

[0011] The valve needle assembly includes a valve needle portion. The inner cavity of the valve needle portion is the valve needle cavity. A first communication hole communicating the valve needle cavity with the first predetermined gap is formed in the side wall of the valve needle portion. The first communication hole and the first predetermined gap form the circulation channel.

[0012] Optionally, at least a part of the valve needle assembly is located in the guiding component inner cavity of the guiding component. There is a second predetermined gap between the inner wall portion of the guiding component and the outer wall portion of the valve needle portion. The second predetermined gap is communicated with the screw rod cavity.

[0013] The valve needle assembly includes a valve needle portion. The inner cavity of the valve needle portion is the valve needle cavity. A second communication hole communicating the valve needle cavity with the second predetermined gap is formed in the side wall of the valve needle portion. The second communication hole and the second predetermined gap form the circulation channel.

[0014] Optionally, the screw rod assembly includes a screw rod and a bushing. The valve needle assembly further includes a valve needle sleeve sleeved on the screw rod. There is a third predetermined gap between the screw rod and the valve needle sleeve. The third predetermined gap is communicated with the screw rod cavity. The bushing and the valve needle sleeve are axially abutted against each other to isolate the valve needle cavity from the screw rod cavity through the bushing and the valve needle sleeve.

[0015] Optionally, in the end faces where the valve needle sleeve abuts against the bushing, at least one of the end faces is provided with a communication groove, and the communication groove communicates the third predetermined gap with the valve needle cavity.

[0016] Optionally, both the valve needle sleeve and the bushing are provided with the communication grooves, and the communication grooves of the two are communicated.

[0017] Optionally, a valve port is defined in the valve core seat, the valve needle portion includes a body portion that cooperates with the valve port, and the valve needle portion is an integrally formed structure.

[0018] Optionally, a valve port is defined in the valve seat, the valve needle assembly includes a sleeve portion and a valve head portion that cooperates with the valve port, the guiding member provides guidance to both the nut and the valve head portion of the valve needle assembly, a through hole is defined at an end of the guiding member, and the valve head portion extends into the valve seat cavity of the valve seat through the through hole to approach or move away from the valve port. Description of the Drawings

[0019] Figure 1 Schematic structural view of the electronic expansion valve provided by the present invention in the first specific embodiment;

[0020] Figure 2 is Figure 1 partial enlarged view of;

[0021] Figure 3 Schematic structural view of the electronic expansion valve provided by the present invention in the second specific embodiment;

[0022] Figure 4 is Figure 3 schematic structural view of the valve needle assembly in a specific embodiment of;

[0023] Figure 5 is Figure 3 schematic structural view of the valve needle assembly in another specific embodiment of;

[0024] Figure 6 Schematic structural view of the cooperation between the valve needle sleeve, the bushing and the lead screw in the electronic expansion valve provided by the present invention in the first specific embodiment;

[0025] Figure 7 is Figure 6 schematic structural view of the valve needle sleeve in;

[0026] Figure 8 Schematic structural view of the cooperation between the valve needle sleeve, the bushing and the lead screw in the electronic expansion valve provided by the present invention in the second specific embodiment;

[0027] Figure 9 is Figure 8 schematic structural view of the bushing in;

[0028] Figure 10 Schematic structural view of the cooperation between the valve needle sleeve, the bushing and the lead screw in the electronic expansion valve provided by the present invention in the second specific embodiment.

[0029] Figures 1 - 10 in:

[0030] 1 valve core seat, 11 valve seat, 2 valve needle assembly, 21 valve needle part, 211 first communication hole, 212 second communication hole, 22 guiding part, 23 valve needle cavity, 24 spring, 25 valve needle sleeve, 26 gasket, 27 ball bearing, 28 communication groove, 29 body part, 291 boss;

[0031] 3 lead screw assembly, 31 lead screw, 32 bushing, lead screw cavity 33;

[0032] 4 valve body, 41 valve cavity, 42 connecting pipe;

[0033] 5 housing, 6 nut, 7 rotor component, 8 electromagnetic coil;

[0034] S1 first predetermined gap, S2 second predetermined gap, S3 third predetermined gap. Detailed implementation manners

[0035] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Please refer to the attached Figures 1 - 5 , where Figure 1 is a schematic structural diagram of the electronic expansion valve provided by the present invention in the first specific embodiment; Figure 2 is Figure 1 a partial enlarged view of Figure 3 is a schematic structural diagram of the electronic expansion valve provided by the present invention in the second specific embodiment; Figure 4 is Figure 3 a schematic structural diagram of the valve needle assembly in a specific embodiment of Figure 5 is Figure 3 a schematic structural diagram of the valve needle assembly in another specific embodiment of

[0037] In a specific embodiment, the present invention provides an electronic expansion valve. As shown in Figure 1 , the electronic expansion valve includes a valve body part and a driving part. Among them, the valve body part includes a valve core seat 1, a valve body 4 and a valve needle assembly 2. The valve body 4 is connected with two connecting pipes 42, and the two connecting pipes 42 are communicated with the valve cavity 41 of the valve body 4. The valve core seat 1 is provided with a valve port, and the opening degree of the valve port is controlled by the valve needle assembly 2, so as to adjust the flow rate of the refrigerant entering the valve cavity 41.

[0038] Meanwhile, the driving part includes a housing 5, a lead screw assembly 3 and a nut 6 which are arranged in the inner cavity of the housing 5 and are threadedly connected. Among them, the nut 6 is fixed to the valve body 4. It also includes an electromagnetic coil 8 located outside the housing 5. A rotor component 7 is fixed to the end of the lead screw assembly 3. When the electromagnetic coil 8 is energized, a magnetic field is generated, and the rotor component 7 drives the lead screw 32 in the lead screw assembly 3 to rotate in the magnetic field. At the same time as the lead screw assembly 3 rotates, it can also move axially within the nut 6. The valve needle assembly 2 is axially connected to the lead screw assembly 3, so that the lead screw assembly 3 drives the valve needle assembly 2 to move axially, thereby changing the opening degree of the valve port.

[0039] Further, in order to enable the lead screw assembly 3 to drive the valve needle 2 to move axially when rotating within the nut 6, the electronic expansion valve further includes the following structure. As Figure 2 shown, a bushing 32 is fixed to the end of the lead screw 31 in the lead screw assembly 3 close to the valve needle assembly 2. Correspondingly, the valve needle assembly 2 includes a valve needle portion 21. A valve needle sleeve 25 is fixed to the end of the valve needle portion 21 close to the lead screw 31. The valve needle portion 21 has a valve needle cavity 23. Both the bushing 32 and the valve needle sleeve 25 are located within the valve needle cavity 23. A spring 24 in a compressed state is also provided within the valve needle cavity 23. The spring 24 is pressed between the inner wall of the valve needle cavity 23 and the first axial end face of the bushing 32. The second axial end face of the bushing 32 abuts against the axial end face of the valve needle sleeve 25, so that the valve needle portion 21 and the lead screw 31 are axially connected through the bushing 32, the valve needle sleeve 25 and the spring 24.

[0040] At the same time, both ends of the lead screw 31 in the axial direction are connected to the valve needle assembly 2 and the rotor component 7 respectively. In order to provide space for the axial movement of the valve needle portion 21, a lead screw cavity 33 is formed between the end of the lead screw 31 close to the valve needle portion 21 and the nut 6. When the opening degree of the valve port increases, the lead screw 31 drives the valve needle portion 21 into the lead screw cavity 33. Among them, as Figure 1 and Figure 2 shown, the lead screw 31 has an external thread portion, which is threadedly connected to the nut 6 to form a threaded mating portion. There is a certain radial clearance between the lead screw 31 and the inner wall of the nut 6 below the threaded mating portion, and this radial clearance forms the lead screw cavity 33. Specifically, the part below the threaded mating portion and the part above the valve needle sleeve 25 form the lead screw cavity 33 between them.

[0041] The working process of the above-mentioned electronic expansion valve is as follows: when the lead screw 31 moves axially in the direction away from the valve port, since the first end face of the bushing 32 abuts axially against the valve needle sleeve 25, the valve needle portion 21 moves axially in the direction away from the valve port under the action of the thrust force and the elastic force of the spring 24 to increase the opening degree of the valve port.

[0042] Before the valve needle portion 21 contacts the valve port, when the valve needle portion 21 moves toward the valve port, the first end surface of the bushing 23 axially abuts against the valve needle sleeve 25, so that the valve needle portion 21 moves axially toward the valve port under the action of the thrust and the elastic force of the spring 24 to reduce the opening of the valve port.

[0043] It is understandable that Figure 2 As shown, when the valve needle 21 contacts the valve port and the pressure in the valve needle chamber 23 is too high, the valve needle component 21 is blocked and cannot be opened. Therefore, in order to ensure that the electronic expansion valve can work properly, it is necessary to avoid excessive pressure in the valve needle chamber 23 to avoid liquid sealing between the components in the refrigerant environment. Specifically, the valve needle chamber 23 and the screw rod chamber 31 can be connected to balance the pressure between the two, thereby avoiding excessive pressure in the valve needle chamber 23 and promoting the normal operation of the electronic expansion valve.

[0044] Normally, the connection between the valve needle chamber 23 and the screw rod chamber 33 is mainly achieved through the gap between the valve needle sleeve 25, the bushing 32 and the screw rod 3. However, the gap is small, which leads to a slow or even impossible pressure balance between the valve needle chamber 23 and the screw rod chamber 31 when the system pressure fluctuates. When liquid is present, the gap between the valve needle sleeve 25, the bushing 32 and the screw rod 31 may be sealed due to the pressure difference in the refrigerant environment, resulting in the formation of a closed cavity in the valve needle chamber 23 and the screw rod chamber 33, which leads to the inability to balance the pressure between the screw rod chamber 31 and the valve needle chamber 33, thereby affecting the normal operation of the electronic expansion valve. When the refrigerant temperature changes and causes the pressure in the valve needle chamber 23 to increase to a level that exceeds its pressure tolerance, the high pressure in the valve needle chamber 23 causes the elastic connection between the valve needle portion 21 and the screw rod 31 to become a rigid connection, affecting the reliability and accuracy of the electronic expansion valve.

[0045] In addition, as mentioned above, when the electronic expansion valve is in the process of fully closing and fully opening the valve port, the first end face of the bushing 32 is axially abutted against the valve needle sleeve 25. Therefore, during this process, the bushing 32 and the valve needle sleeve 25 are in close contact, and the gap between the two is very small or there is no gap, resulting in a slow pressure balance speed or failure to balance the pressure between the valve needle chamber 23 and the screw chamber 33 during this process.

[0046] Based on this, in order to solve the above technical problems, in the electronic expansion valve provided by the present invention, the valve needle chamber 23 and the screw rod chamber 33 are connected not only through the gap between the valve needle sleeve 25, the bushing 32 and the screw rod 31, but also through a balancing channel, and during the operation of the electronic expansion valve, the balancing channel is always connected.

[0047] Therefore, in the present invention, by providing a balance channel, the pressure balance between the valve needle cavity 23 and the lead screw cavity 33 can be quickly achieved through the balance channel, thereby preventing the valve needle cavity 23 from being liquid-sealed in the refrigerant environment to form a closed chamber, so as to avoid the elastic connection between the lead screw assembly 3 and the valve needle assembly 2 from becoming a rigid connection and improving the reliability of the electronic expansion valve. Moreover, through the provision of the above-mentioned balance channel, when the electronic expansion valve moves from the valve needle part 21 just contacting the valve port to the valve port being fully opened, the pressure between the valve needle cavity 23 and the lead screw cavity 33 can also be quickly balanced.

[0048] Specifically, as Figure 1 and 2 shown in the embodiment, the valve core seat 1 has a valve core seat cavity, and the valve needle part 21 of the valve needle assembly 2 is located in the valve core seat cavity and can axially move in the valve core seat cavity. Therefore, there is a first predetermined gap S1 between the inner wall of the valve core seat 1 and the outer wall of the valve needle part 21, and the first predetermined gap S1 communicates with the lead screw cavity 33. At the same time, a first communication hole 211 communicating the valve needle cavity 23 and the first predetermined gap S1 is provided on the side wall of the valve needle part 21, so that the valve needle cavity 23 and the lead screw cavity 31 communicate with each other through the first predetermined gap S1 and the first communication hole 211, that is, the first communication hole 211 and the first predetermined gap S1 form the above-mentioned balance channel.

[0049] In the embodiment as Figures 3 - 5 shown, the valve needle lead screw assembly includes a valve needle assembly 2, a lead screw assembly 3 and a guiding member 22, and the guiding member cavity of the guiding member 22 forms a valve needle cavity 23. The valve needle assembly 2 is located in the guiding member cavity and can axially move. At the same time, the guiding member 22 is located in the valve core seat cavity. There is a second predetermined gap S2 between the inner wall part of the valve core seat 1 and the outer wall part of the guiding member 22. The second predetermined gap S2 communicates with the lead screw cavity 33, and a second communication hole 212 communicating the valve needle cavity 23 and the second predetermined gap S2 is provided on the side wall of the guiding member 22. The second communication hole 212 and the second predetermined gap S2 form a flow channel.

[0050] In this embodiment, the above-mentioned balance channel can be formed only by providing a first communication hole 211 on the side wall of the valve needle part 21 or a second communication hole 212 on the side wall of the guiding member 22, which has the advantage of convenient processing. Moreover, after adding the communication hole to the valve needle part 21 or the guiding member, it does not affect their cooperation relationship with other components and the working process of the electronic expansion valve. Therefore, the communication hole in this embodiment can improve the working reliability of the electronic expansion valve without causing other hidden dangers.

[0051] In addition, according to actual needs, a plurality of the above-mentioned communication holes can be provided on the side wall of the valve needle part 21 or the side wall of the guiding member 22, and the communication hole can be a through hole of any shape. Therefore, the present invention does not limit the number and shape of the communication holes.

[0052] Please continue to refer to the appendix Figures 6 - 10 , where Figure 6 is a schematic diagram of the mating structure of the valve needle sleeve, bushing and lead screw in the first specific embodiment of the electronic expansion valve provided by the present invention; Figure 7 is Figure 6 a schematic diagram of the structure of the valve needle sleeve in Figure 8 is a schematic diagram of the mating structure of the valve needle sleeve, bushing and lead screw in the second specific embodiment of the electronic expansion valve provided by the present invention; Figure 9 is Figure 8 a schematic diagram of the structure of the bushing in Figure 10 is a schematic diagram of the mating structure of the valve needle sleeve, bushing and lead screw in the second specific embodiment of the electronic expansion valve provided by the present invention.

[0053] In another embodiment, as Figures 6 - 10 shown, the valve needle sleeve 25 is sleeved on the outer periphery of the lead screw 31, and the lead screw 31 can rotate within the valve needle sleeve 25. Therefore, there is a third predetermined gap S3 between the lead screw 31 and the valve needle sleeve 25, and the third predetermined gap S3 communicates with the lead screw cavity 33. At the same time, in the end faces where the valve needle sleeve 25 abuts against the bushing 32, at least one of the end faces is provided with a communication groove 28, and the communication groove 28 communicates the third predetermined gap S3 with the valve needle cavity 23. Therefore, the valve needle cavity 23 and the lead screw cavity 33 are communicated through the third predetermined gap S3 and the communication groove 28, and the communication groove 28 and the third predetermined gap S3 form the above-mentioned flow passage.

[0054] As Figure 6 and Figure 7 shown, the communication groove 28 is only provided on the valve needle sleeve 25. As Figure 8 and Figure 9 shown, the communication groove 28 is only provided on the bushing 32. As Figure 10 shown, the communication groove 28 is provided on both the valve needle sleeve 25 and the bushing 32.

[0055] In this embodiment, the above-mentioned flow passage can be formed only by providing the communication groove 28 on the bushing 32 and / or the valve needle sleeve 25, which also has the advantage of convenient processing. Moreover, after the communication groove 28 is provided on the bushing 32 and / or the valve needle sleeve 25, it does not affect their mating relationship with other components and the working process of the electronic expansion valve. Therefore, the communication groove 28 in this embodiment can improve the working reliability of the electronic expansion valve without causing other potential hazards.

[0056] Specifically, a plurality of the above-mentioned communication grooves 28 can be provided, and they can be grooves of any shape. Therefore, the number and shape of the communication grooves 28 are not limited in the present invention.

[0057] Furthermore, as Figure 7 shown, when both the valve needle sleeve 25 and the bushing 32 are provided with the communication groove 28, the two communication grooves 28 are directly communicated.

[0058] In addition, in the electronic expansion valve of the present invention, the communication channel can also be any combination of the above two embodiments. Taking the electronic expansion valve shown in Figure 1 and Figure 2 as an example, a first communication hole 211 is formed in the side wall of the valve needle portion 21. At the same time, a communication groove 28 is formed in the bushing 23 and / or the valve needle sleeve 25; or a first communication hole 211 is formed in the side wall of the valve needle portion 21. At the same time, a communication groove 28 is formed in the bushing 23 and / or the valve needle sleeve 25.

[0059] In each of the above embodiments, as shown in Figure 2 a body portion 29 that cooperates with the valve port is integrally formed on the valve needle portion 21, and the cross section of the body portion 29 is conical.

[0060] In addition, as shown in Figure 4 and Figure 5 the valve needle assembly 2 includes a sleeve portion and a valve head portion that cooperates with the valve port. The guiding member 22 provides guidance to both the nut 6 and the valve head portion of the valve needle assembly 2 at the same time. A through hole is formed at the end of the guiding member 22, and the valve head portion extends into the valve seat cavity of the valve seat 11 through the through hole to approach or move away from the valve port.

[0061] Specifically, the body portion 29 has a boss 291 extending radially outward. One end of the body portion 29 passes through the mounting hole, and the boss 291 abuts against the inner wall of the guiding member 22. The spring 24 is pressed between the bushing 32 and the body portion 29, so that the body portion 29 and the guiding member 22 are axially connected through the spring 24 and the boss 291.

[0062] Further, a gasket 26 is provided between the boss 291 and the inner wall of the guiding member 22 to buffer the impact load between the guiding member 22 and the body portion 29.

[0063] In addition, as shown in Figure 10 the lead screw 31 is connected to the body portion 29 through a ball bearing 27, so that the lead screw 31 can rotate freely. At the same time, when the lead screw 31 moves axially, it can also drive the body portion 212 to move axially to change the opening degree of the valve port.

[0064] The above provides a detailed introduction to an electronic expansion valve provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An electronic expansion valve, characterized in that, it includes a valve core seat (1) and a valve needle screw rod assembly. The valve needle screw rod assembly includes a valve needle assembly (2) and a screw rod assembly (3). The valve core seat (1) is fixedly connected to a nut (6) that is in threaded engagement with the screw rod assembly (3). The screw rod assembly (3) drives the valve needle assembly (2) to move axially by being in threaded engagement with the nut (6) to adjust the refrigerant flow rate through the valve port of the electronic expansion valve; the valve needle assembly (2) forms a valve needle cavity (23). A screw rod cavity (33) is formed between one end of the screw rod assembly (3) close to the valve needle assembly (2) and the nut (6). The valve needle cavity (23) is communicated with the screw rod cavity (33) through a flow passage; the screw rod assembly (3) includes a screw rod (31) and a bushing (32). The valve needle assembly (2) further includes a valve needle sleeve (25) sleeved on the screw rod (31). The bushing (32) abuts against the valve needle sleeve (25) in the axial direction. The valve needle cavity (23) is isolated from the screw rod cavity (33) by the bushing (32) and the valve needle sleeve (25); a third predetermined gap (S3) is provided between the screw rod (31) and the valve needle sleeve (25), and the third predetermined gap (S3) is communicated with the screw rod cavity (33); in the end face where the valve needle sleeve (25) abuts against the bushing (32), at least one of the end faces is provided with a communication groove (28), and the communication groove (28) communicates the third predetermined gap (S3) with the valve needle cavity (23); the valve needle cavity (23) is also communicated with the screw rod cavity (33) through a balance passage, and during the operation of the electronic expansion valve, the balance passage is always conducting.

2. An electronic expansion valve, characterized in that, it includes a valve seat (11), a valve needle screw rod assembly, and a guiding component (22). The valve needle screw rod assembly includes a valve needle assembly (2) and a screw rod assembly (3). The guiding component (22) is fixedly connected to a nut (6) that is in threaded engagement with the screw rod assembly (3). The screw rod assembly (3) drives the valve needle assembly (2) to move axially by being in threaded engagement with the nut (6) to adjust the refrigerant flow rate through the valve port of the electronic expansion valve; the guiding component (22) has a guiding component inner cavity. The valve needle assembly (2) is located in the guiding component inner cavity. The valve needle assembly (2) forms a valve needle cavity (23). A screw rod cavity (33) is formed between one end of the screw rod assembly (3) close to the valve needle assembly (2) and the nut (6). The valve needle cavity (23) is communicated with the screw rod cavity (33) through a flow passage; the screw rod assembly (3) includes a screw rod (31) and a bushing (32). The valve needle assembly (2) further includes a valve needle sleeve (25) sleeved on the screw rod (31). The bushing (32) abuts against the valve needle sleeve (25) in the axial direction. The valve needle cavity (23) is isolated from the screw rod cavity (33) by the bushing (32) and the valve needle sleeve (25); There is a third predetermined gap (S3) between the lead screw (31) and the valve needle sleeve (25), and the third predetermined gap (S3) communicates with the lead screw cavity (33); In the end faces where the valve needle sleeve (25) abuts against the bushing (32), at least one of the end faces is provided with a communication groove (28), and the communication groove (28) communicates the third predetermined gap (S3) with the valve needle cavity (23); The valve needle cavity (23) and the lead screw cavity (33) are also communicated through a balance channel, and during the operation of the electronic expansion valve, the balance channel is always conducting.

3. The electronic expansion valve according to claim 1, characterized in that The valve needle assembly (2) is located in the valve core seat cavity of the valve core seat (1) and can axially move in the valve core seat cavity. There is a first predetermined gap (S1) between the inner wall of the valve core seat (1) and the outer wall of the valve needle assembly (2), and the first predetermined gap (S1) communicates with the lead screw cavity (33); The valve needle assembly (2) includes a valve needle part (21). The inner cavity of the valve needle part (21) is the valve needle cavity (23). A first communication hole (211) communicating the valve needle cavity (23) with the first predetermined gap (S1) is provided on the side wall of the valve needle part (21), and the first communication hole (211) and the first predetermined gap (S1) form the flow channel.

4. The electronic expansion valve according to claim 2, characterized in that The valve needle assembly (2) includes a valve needle part (21). The inner cavity of the valve needle part (21) is the valve needle cavity (23). There is a second predetermined gap (S2) between the inner wall of the guiding part (22) and the outer wall of the valve needle part (21). A second communication hole (212) communicating the valve needle cavity (23) with the second predetermined gap (S2) is provided on the side wall of the valve needle part (21), and the second communication hole (212) and the second predetermined gap (S2) form the flow channel; at least a part of the valve needle assembly (2) is located in the guiding part cavity of the guiding part (22), and the second predetermined gap (S2) communicates with the lead screw cavity (33).

5. The electronic expansion valve according to claim 1, characterized in that Both the valve needle sleeve (25) and the bushing (32) are provided with communication grooves (28), and the communication grooves (28) of the two communicate with each other.

6. The electronic expansion valve according to claim 3, characterized in that The valve core seat (1) is provided with a valve port. The valve needle part (21) includes a body part (29) that cooperates with the valve port, and the valve needle part (21) is an integrally formed structure.

7. The electronic expansion valve according to claim 4, characterized in that The valve seat (11) is provided with a valve port. The valve needle assembly (2) includes a sleeve portion and a valve head portion that cooperates with the valve port. The guiding member (22) provides guidance to both the nut (6) and the valve head portion of the valve needle assembly (2). A through hole is provided at the end of the guiding member (22). The valve head portion extends into the valve seat cavity of the valve seat (11) through the through hole to approach or move away from the valve port.

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