Electronic expansion valve

Abstract

An electronic expansion valve, comprising a valve seat assembly, a valve core assembly, a screw, and a second elastic member. The valve seat assembly has a valve cavity; the wall of the valve cavity is provided with a first valve port and a second valve port which are spaced apart from each other in the axial direction of the electronic expansion valve; at least part of the valve core assembly is provided in the valve cavity and comprises a first valve core, a second valve core, and a first elastic member; the first valve core is movable between a first position at which the first valve port is blocked and a second position at which the second valve port is blocked; the second valve core is used for driving the first valve core to move; the first elastic member is connected to the first valve core and the second valve core and is used for applying to the first valve core a first preloading force for blocking the first valve port; the screw is used for driving the second valve core to move in the axial direction of the electronic expansion valve; and the second elastic member is connected to the second valve core and the screw and is used for applying, to the first valve core by means of the second valve core, a second preloading force for blocking the second valve port.

Description

Electronic expansion valve

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to Chinese Patent Applications No. 202410875837.4, entitled “Electronic expansion valve”, filed on July 1, 2024, No. 202421536457.X, entitled “Electronic expansion valve”, filed on July 1, 2024, and No. 202421538950.5, entitled “Valve core assembly and electronic expansion valve”, filed on July 1, 2024, the contents of all of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of valves, and in particular, to an electronic expansion valve. BACKGROUND

[0004] An electronic expansion valve is a device used to control the flow of refrigerant in a refrigeration cycle, commonly used in refrigeration and air conditioning systems. It is an expansion valve that adjusts the flow of refrigerant through electronic control to ensure the normal operation and high efficiency of the refrigeration system.

[0005] The electronic expansion valve in the related art is often provided with multiple valve ports, and the valve core assembly is switched between different valve ports to achieve switching of different flow paths. However, the sealing performance between the valve core assembly and the valve port in the related art is poor, which leads to easy fluid leakage of the electronic expansion valve. SUMMARY

[0006] The electronic expansion valve of the present disclosure includes a valve seat assembly, a valve core assembly, a screw rod, and a second elastic member. The valve seat assembly has a valve cavity, and the cavity wall of the valve cavity has a first valve port and a second valve port arranged at intervals along the axial direction of the electronic expansion valve. At least part of the valve core assembly is arranged in the valve cavity and includes a first valve core, a second valve core, and a first elastic member. The first valve core is movable between a first position for blocking the first valve port and a second position for blocking the second valve port. The second valve core is used to drive the first valve core to move. The first elastic member is connected to the first valve core and the second valve core. After the first valve core is located at the first position, the second valve core can move relative to the first valve core in a direction close to the first valve port, so that the compression amount of the first elastic member increases and is used to apply a first pre-tightening force to the first valve core for blocking the first valve port. The screw rod is used to drive the second valve core to move along the axial direction of the electronic expansion valve. The second elastic member is connected to the second valve core and the screw rod. After the first valve core is located at the second position, the screw rod can move relative to the first valve core in a direction away from the second valve port, so that the compression amount of the second elastic member increases and is used to apply a second pre-tightening force to the first valve core for blocking the second valve port through the second valve core. Attached Figure Description

[0007] Figure 1 shows a side view of the electronic expansion valve according to the first embodiment of this disclosure.

[0008] Figure 2 shows a perspective view of the electronic expansion valve according to the first embodiment of this disclosure.

[0009] Figure 3 shows a cross-sectional view along section line AA of Figure 1.

[0010] Figure 4 shows a schematic diagram when the first valve core and the second valve core are not installed in place.

[0011] Figure 5 shows a schematic diagram of the exploded view of Figure 4.

[0012] Figure 6 shows a cross-sectional view along the BB section line of Figure 4.

[0013] Figure 7 shows a cross-sectional view of the electronic expansion valve according to a second embodiment of the present disclosure.

[0014] Figure 8 shows a three-dimensional schematic diagram of the guide section in Figure 7.

[0015] Figure 9 shows a cross-sectional view of an electronic expansion valve according to a third embodiment of this disclosure.

[0016] Figure 10 shows a three-dimensional schematic diagram of the second guide rod in Figure 9.

[0017] Figure 11 shows a cross-sectional view of an electronic expansion valve according to a fourth embodiment of this disclosure.

[0018] Figure 12 shows a three-dimensional schematic diagram of the second guide rod in Figure 11.

[0019] Figure 13 shows a cross-sectional view of an electronic expansion valve according to a fifth embodiment of this disclosure.

[0020] Figure 14 shows a cross-sectional view of an electronic expansion valve according to a sixth embodiment of the present disclosure.

[0021] Figure 15 shows a cross-sectional view of an electronic expansion valve according to a seventh embodiment of this disclosure. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0023] It is to be understood that the terms "including", "comprising", "having" and variations thereof herein are intended to cover all possible combinations of the listed steps or elements. For example, a process, method, system, product, or apparatus that comprises a list of steps or elements is not necessarily limited to only those steps or elements but can include other steps or elements not expressly listed or inherent to such process, method, system, product, or apparatus.

[0024] As shown in FIGS. 1-3, the electronic expansion valve of the first embodiment of the present disclosure comprises a valve seat assembly 100, a valve core assembly 200, a rotor assembly 810, an outer cover 820, a nut seat 830 and a screw rod 300.

[0025] The valve seat assembly 100 has a valve cavity 110, at least part of the valve core assembly 200 is arranged in the valve cavity 110 and is movable relative to the valve seat assembly 100 along the axial direction of the electronic expansion valve. The outer cover 820 is fixedly connected to the valve seat assembly 100, for example by welding, but not limited thereto. The rotor assembly 810 is movably arranged in the outer cover 820 and is used to be coupled with a coil assembly (not shown in the figure) arranged on the outer periphery of the outer cover 820. The nut seat 830 is fixedly connected to the valve seat assembly 100 and arranged in the outer cover 820. The screw rod 300 is arranged in the outer cover 820 and connected with the rotor assembly 810 and screwed with the nut seat 830.

[0026] When the electronic expansion valve is working, the rotor assembly 810 can be driven to rotate by applying a pulse signal to the coil assembly, and since the nut seat 830 is fixed and screwed with the screw rod 300, the screw rod 300 can move reciprocatingly along the axial direction of the electronic expansion valve, thereby driving the valve core assembly 200 to move in the valve cavity 110 relative to the valve seat assembly 100.

[0027] The valve seat assembly 100 can comprise a first valve seat 120, a second valve seat 130 and a third valve seat 150. The first valve seat 120, the second valve seat 130 and the third valve seat 150 are sequentially connected along the axial direction of the electronic expansion valve and jointly enclose the valve cavity 110.

[0028] The valve seat assembly 100 has a first opening 103, a second opening 104 and a third opening 105 which are in communication with the valve cavity 110 and are sequentially arranged along the axial direction of the electronic expansion valve. The cavity wall of the valve cavity 110 has a valve port 110a. It is to be understood that the number of valve ports 110a can be one or more, and when the number of valve ports 110a is two, the two valve ports 110a are defined as a first valve port 101 and a second valve port 102 respectively. The first valve port 101 is located between the second opening 104 and the third opening 105, and the second valve port 102 is located between the second opening 104 and the first opening 103.

[0029] In the embodiments of the present disclosure, the second valve seat 130 has the first opening 103, the second opening 104 and the second valve port 102, and the third valve seat 150 has the third opening 105 and the first valve port 101, but the present disclosure is not limited thereto.

[0030] As shown in FIGS. 3-6, the valve core assembly 200 includes a first valve core 210, a second valve core 220 and a first elastic member 230, the first valve core 210 is movable between a first position for blocking the first valve port 101 and a second position for blocking the second valve port 102, the second valve core 220 is used to drive the first valve core 210 to move, the first elastic member 230 is connected to the first valve core 210 and the second valve core 220, and when the first valve core 210 is in the first position, the second valve core 220 can move relative to the first valve core 210 in a direction close to the first valve port 101, so that the compression amount of the first elastic member 230 increases and is used to apply a first pre-tightening force for blocking the first valve port 101 to the first valve core 210. The screw rod 300 is used to drive the second valve core 220 to move along the axial direction of the electronic expansion valve.

[0031] The electronic expansion valve further includes a second elastic member 500 connected to the second valve core 220 and the screw rod 300, and when the first valve core 210 is in the second position, the screw rod can move relative to the first valve core 210 in a direction away from the second valve port 102, so that the compression amount of the second elastic member 500 increases and is used to apply a second pre-tightening force for blocking the second valve port 102 to the first valve core 210 through the second valve core 220.

[0032] It can be understood that the sealing performance between the valve core assembly and the valve port in the related art is poor, and there is a problem that fluid is easy to leak.

[0033] Therefore, the electronic expansion valve in the embodiments of the present disclosure includes the first elastic member 230 and the second elastic member 500, the first elastic member 230 can apply the first pre-tightening force for blocking the first valve port 101 to the first valve core 210, and the second elastic member 500 can apply the second pre-tightening force for blocking the second valve port 102 to the first valve core 210, so that the sealing performance of the first valve core 210 for blocking the first valve port 101 or the second valve port 102 is significantly improved, fluid leakage of the electronic expansion valve is prevented, and the working reliability is improved. In addition, in the electronic expansion valve in the embodiments of the present disclosure, the screw rod 300 drives the first valve core 210 to move between the first position and the second position through the second valve core 220, the first pre-tightening force provided by the first elastic member 230 acts on the first valve core 210 and the second valve core 220 respectively, and the second pre-tightening force provided by the second elastic member 500 acts on the screw rod 300 and the second valve core 220 respectively, so that the first pre-tightening force and the second pre-tightening force do not affect each other, it is ensured that the first pre-tightening force and the second pre-tightening force are large enough, and the sealing performance of the first valve core 210 for blocking the first valve port 101 and the second valve port 102 is further improved.

[0034] In an embodiment, the first elastic member 230 and the second elastic member 500 can be compression springs, but are not limited thereto. For example, the first elastic member 230 and the second elastic member 500 can also be rubber members or other components capable of providing elastic force under compression.

[0035] As shown in FIGS. 3, 5 and 6, the first valve core 210 includes a first component and a second component in interference fit. In the embodiment of the present disclosure, the first component is a valve needle 211, and the second component is a first valve sleeve 212. The valve needle 211 is used to block the first valve port 101 or the second valve port 102. At least a portion of the first valve sleeve 212 is sleeved on the outer periphery of the valve needle 211 and is fixedly connected with the valve needle 211; wherein the first valve sleeve 212 is limitingly connected with the second valve core 220, so as to move the first valve core 210 from the first position to the second position.

[0036] The portion of the valve needle 211 surrounded by the first valve sleeve 212 has an end face 2111. The inner peripheral surface of the first valve sleeve 212 is provided with a first stop portion 2121, and the first stop portion 2121 is arranged along the axial direction of the electronic expansion valve and spaced apart from the end face 2111. The portion of the second valve core 220 extending into the first valve sleeve 212 is provided with a flange 2211, and the flange 2211 is movable between the first stop portion 2121 and the end face 2111 to compress the first elastic member 230; the flange 2211 can also pull the first stop portion 2121 to move the first valve core 210 from the first position to the second position.

[0037] The second valve core 220 includes a valve core seat 221 and a second valve sleeve 222, and an axial end of the second valve sleeve 222 is fixedly connected with the valve core seat 221, for example, by welding, screwing, interference fit, etc. At least a portion of the valve core seat 221 is arranged in the first valve core 210, and is used to pull the first valve core 210 to move from the first position to the second position, or to compress the first elastic member 230. An end of the second elastic member 500 and the screw rod 300 is arranged in the second valve sleeve 222. Wherein the valve core seat 221 has the flange 2211, and the flange 2211 is movable between the first stop portion 2121 and the end face 2111. When the flange 2211 moves in the direction close to the first valve port 101, the first elastic member 230 can be compressed. When the flange 2211 moves in the direction away from the first valve port 101, the first stop portion 2121 can be pulled to move the first valve core 210 from the first position to the second position.

[0038] The inner circumferential surface of the second valve sleeve 222 has a second stop portion 2221. The screw rod 300 comprises a rod portion 310 and a third stop portion 320, the rod portion 310 is screwed with the nut seat 830, the third stop portion 320 is connected to one end of the rod portion 310 and is located in the second valve sleeve 222 and is movable between the second stop portion 2221 and the valve core seat 221, one end of the second elastic member 500 abuts against the second stop portion 2221, and the other end abuts against the third stop portion 320.

[0039] As shown in FIG. 3 and FIG. 6, the third stop portion 320 comprises a bearing 321 and a protective sheet 322. The inner ring of the bearing 321 is sleeved on the outer circumference of the rod portion 310 and is fixedly connected with the rod portion 310; the protective sheet 322 is arranged on the side of the bearing 321 facing the second stop portion 2221, and the other end of the second elastic member 500 abuts against the protective sheet 322.

[0040] In the embodiment of the present disclosure, the protective sheet 322 can protect the bearing 321, preventing the second elastic member 500 from directly abutting against the bearing 321 and causing the bearing 321 to deform.

[0041] The valve needle 211 has a containing groove 2112 recessed from the end face 2111 in the axial direction of the electronic expansion valve away from the second valve core 220; the first elastic member 230 is contained in the containing groove 2112, one end of the first elastic member 230 abuts against the groove bottom surface of the containing groove 2112, and the other end abuts against the second valve core 220.

[0042] In the embodiment of the present disclosure, the containing groove 2112 can limit the position of the first elastic member 230, preventing the position of the first elastic member 230 from changing and affecting the elastic pre-tightening force provided by the first elastic member 230.

[0043] In an embodiment, the valve needle 211 is in interference fit with the first valve sleeve 212. For example, the part of the valve needle 211 surrounded by the first valve sleeve 212 has a first fit section 2113 and a second fit section 2114, the first fit section 2113 and the second fit section 2114 are arranged in the axial direction of the electronic expansion valve, and the first fit section 2113 is closer to the second valve core 220 than the second fit section 2114; the first fit section 2113 is in clearance fit with the inner circumferential surface of the first valve sleeve 212, and the second fit section 2114 is in interference fit with the inner circumferential surface of the first valve sleeve 212.

[0044] Of course, in other embodiments, the valve needle 211 and the first valve sleeve 212 can also be connected by welding, screwing or the like.

[0045] The movement process of the valve core assembly 200 and how the first elastic member 230 and the second elastic member 500 provide elastic pre-tightening force will be described in detail below in combination with FIG. 3.

[0046] The process that the first valve core 210 blocks the first valve port 101: the rotor assembly 810 drives the screw rod 300 to rotate, and under the thread cooperation between the screw rod 300 and the nut seat 830, the screw rod 300 moves downward as a whole. During the downward movement of the screw rod 300, the bearing 321 of the screw rod 300 presses against the valve core seat 221, so that the valve needle 211 moves in the direction of blocking the first valve port 101. When the valve needle 211 blocks the first valve port 101 (the first position), the valve needle 211 no longer continues to move, and at this time, the valve core seat 221 continues to move downward, and the compression amount of the first elastic member 230 pressed by the valve core seat 221 increases and provides the first pre-tightening force. Under the action of the first pre-tightening force, the valve needle 211 can tightly block the first valve port 101, improving the sealing performance of the valve needle 211 in blocking the first valve port 101.

[0047] The process that the first valve core 210 blocks the second valve port 102: the rotor assembly 810 drives the screw rod 300 to rotate reversely, and under the thread cooperation between the screw rod 300 and the nut seat 830, the screw rod 300 drives the second valve core 220 to move upward through the second elastic member 500. During the upward movement of the second valve core 220, the flange 2211 contacts the first stop portion 2121 of the first valve sleeve 212, and then the second valve core 220 can drive the first valve core 210 to move to the second position. When the first valve core 210 moves to the second position, the first valve core 210 cannot continue to move upward, and under the action of the first stop portion 2121 stopping the flange 2211, the second valve core 220 also cannot continue to move upward. At this time, the screw rod 300 can continue to move upward under the drive of the rotor assembly 810. During the continuous movement of the screw rod 300, the third stop portion 320 of the screw rod 300 presses the second elastic member 500, so that the compression amount of the second elastic member 500 increases to generate the second pre-tightening force. The second pre-tightening force can continuously abut against the second stop portion 2221 of the second valve sleeve 222, and then the second valve core 220 continuously provides the pulling force for the upward movement of the first valve core 210, so as to maintain the state that the first valve core 210 blocks the second valve port 102. As can be seen, under the action of the second pre-tightening force, the valve needle 211 can tightly block the second valve port 102, improving the sealing performance of the valve needle 211 in blocking the second valve port 102.

[0048] As shown in FIG. 3, there is a movable gap between the valve core seat 221 and the end face 2111 of the valve needle 211 in the axial direction of the electronic expansion valve. The movable gap is used to adjust the number of opening pulses of the electronic expansion valve. Specifically, by setting the size of the movable gap, the number of opening pulses of the device can be adjusted according to the actual situation.

[0049] As shown in FIG. 3, the valve needle 211 has a limiting portion 2116. The first valve core 210 further includes a retaining ring 2117 and a second inner sealing ring 213, the retaining ring 2117 is fixedly connected to the valve needle 211, and the second inner sealing ring 213 is clamped between the limiting portion 2116 and the retaining ring 2117.

[0050] Further, the valve needle 211 also has a stepped structure 2118, and the retaining ring 2117 is in abutting cooperation with the stepped structure 2118. When the retaining ring 2117 is assembled with the valve needle 211, the stepped structure 2118 is in abutting cooperation with the retaining ring 2117, so that the retaining ring 2117 can be prevented from being excessively pressed against the second inner sealing ring 213.

[0051] As shown in FIG. 3, the valve core assembly 200 is further provided with a first inner sealing ring 140 between the valve core assembly 200 and the cavity wall of the valve cavity 110. The first valve sleeve 212 of the first valve core 210 is in movable sealing cooperation with the cavity wall of the valve cavity 110 through the first inner sealing ring 140, and the sealing position between the first valve core 210 and the cavity wall of the valve cavity 110 forms a first sealing ring. The first valve core 210 has a second inner sealing ring 213, the sealing position of the second inner sealing ring 213 with the first valve port 101 forms a second sealing ring, and the sealing position of the second inner sealing ring 213 with the second valve port 102 forms a third sealing ring. The diameter D2 of the second sealing ring is greater than the diameter D1 of the first sealing ring, and the diameter D3 of the third sealing ring is greater than the diameter D1 of the first sealing ring.

[0052] It can be understood that the diameter D2 of the second sealing ring is designed to be greater than the diameter D1 of the first sealing ring, and the diameter D3 of the third sealing ring is designed to be greater than the diameter D1 of the first sealing ring, so as to facilitate the valve core assembly 200 to be loaded into the valve cavity 110 from the bottom of the valve seat assembly 100.

[0053] However, such a design will cause the electronic expansion valve to no longer maintain internal balance as a whole, that is, the valve core assembly 200 is no longer balanced under the action of the fluid.

[0054] Therefore, in the electronic expansion valve of the embodiment of the present disclosure, the relationship between the first pre-tightening force F1 and D2 and D1 satisfies the following inequality: (π×D2 2 ÷4-π×D1 2 ÷4)×ΔP1<F1; wherein D2 is the diameter of the second sealing ring, D1 is the diameter of the first sealing ring, and ΔP1 is the fluid pressure difference between the third opening 105 and the second opening 104 when the electronic expansion valve is connected to the fluid.

[0055] The second pre-tightening force F2 and D3 and D1 satisfy the following inequality: (π×D3 2 ÷4-π×D1 2 ÷4)×ΔP2<F2; wherein D3 is the diameter of the third sealing ring, D1 is the diameter of the first sealing ring, and ΔP2 is the fluid pressure difference between the first opening 103 and the second opening 104 when the electronic expansion valve is connected to the fluid.

[0056] In the embodiment of the present disclosure, F1, D1 and D2 satisfy (π×D2 2 ÷4-π×D1 2F1, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3 2 F1, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3 2 F2, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid.

[0057] Specifically, the second opening 104 of the valve seat assembly 100 is set as the inlet of the fluid, and the first opening 103 and the third opening 105 are set as the outlets of the fluid. When the valve needle 211 blocks the first valve port 101, the fluid enters from the second opening 104 and flows out from the first opening 103. At this time, the upper space of the second inner sealing ring 213 (i.e., the cavity corresponding to the second opening 104 and the first opening 103) is a high-pressure cavity, and the lower space of the second inner sealing ring 213 (i.e., the cavity corresponding to the third opening 105) is a low-pressure cavity. Under normal circumstances, the fluid enters from the second opening 104 and flows out from the first opening 103, at which time the valve needle 211 is subjected to the downward fluid pressure, and the valve needle 211 will not be pushed open by the fluid. However, under abnormal circumstances, if the fluid suddenly enters from the third opening 105, the pressure formed by the fluid is (π x D2 2 F1, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3 2 F1, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3

[0058] Therefore, the first pre-tightening force F1 provided by the first elastic member 230 of the embodiment of the present disclosure is greater than (π x D2 2 F1, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3 2 F1, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3

[0059] Similarly, when the valve needle 211 blocks the second valve port 102, the fluid enters from the second opening 104 and flows out from the third opening 105. At this time, the upper space of the second inner sealing ring 213 (i.e., the cavity corresponding to the first opening 103) is a low-pressure cavity, and the lower space of the second inner sealing ring 213 (i.e., the cavity corresponding to the second opening 104 and the third opening 105) is a high-pressure cavity. Under normal circumstances, the fluid enters from the second opening 104 and flows out from the third opening 105, at which time the valve needle 211 is subjected to the upward fluid pressure, and the valve needle 211 will not be pushed open by the fluid. However, under abnormal circumstances, if the fluid suddenly enters from the first opening 103, the pressure formed by the fluid is (π x D3 2 F2, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3 2 F2, which can prevent fluid leakage caused by the valve needle 211 being pushed open by the reverse force of the fluid; similarly, F2, D1 and D3 satisfy (π x D3

[0060] Therefore, the second pre-tightening force F2 provided by the second elastic member 500 of the embodiment of the present disclosure is greater than (π x D3 2÷ 4 - π x D1 2 ÷ 4) x ΔP2, which can effectively prevent the fluid pressure from pushing the valve needle 211 open, ensuring the sealing of the valve needle 211 to the second valve port 102.

[0061] As shown in FIG. 3, the first inner sealing ring 140 includes an outer sealing ring 141 and an inner sealing ring 142, the inner sealing ring 142 is sleeved on the outer periphery of the first valve sleeve 212, the outer sealing ring 141 is wrapped around the outer periphery of the inner sealing ring 142, and the outer sealing ring 141 applies an elastic pre-tightening force to the inner sealing ring 142 towards the first valve sleeve 212. The combined sealing structure of the outer sealing ring 141 and the inner sealing ring 142 can improve the high-pressure resistance and wear resistance of the dynamic seal.

[0062] In an embodiment, the material of the inner sealing ring 142 can be polytetrafluoroethylene, but is not limited thereto.

[0063] It can be understood that the diameter D1 of the first sealing ring is the outer diameter dimension of the first valve sleeve 212. The diameter D2 of the second sealing ring is the diameter of the circle formed by the tangent point between the R angle at the edge of the first valve port 101 and the lower inclined surface of the second inner sealing ring 213. The diameter D3 of the third sealing ring is the diameter of the circle formed by the tangent point between the R angle at the edge of the second valve port 102 and the upper inclined surface of the second inner sealing ring 213.

[0064] Further, in order to reduce the difference between D2 and D1, and the difference between D3 and D1, and to make the electronic expansion valve as balanced as possible, the R angle at the edge of the first valve port 101 can be reduced, and the taper of the lower inclined surface of the second inner sealing ring 213 can be increased, and the R angle at the edge of the second valve port 102 can be reduced, and the taper of the upper inclined surface of the second inner sealing ring 213 can be increased.

[0065] In an embodiment, the second inner sealing ring 213 is made of a flexible sealing material, such as rubber, polymer, plastic, etc., so as to improve the sealing performance of the second inner sealing ring 213 when sealing the first valve port 101 or the second valve port 102, and prevent leakage.

[0066] When the first valve port 101 is closed, at least part of the lower inclined surface of the second inner sealing ring 213 is located in the first valve port 101, which can ensure that the valve core assembly 200 can be guided by the lower inclined surface of the second inner sealing ring 213 in case of deflection. When the second valve port 102 is closed, at least part of the upper inclined surface of the second inner sealing ring 213 is located in the second valve port 102, which can ensure that the valve core assembly 200 can be guided by the upper inclined surface of the second inner sealing ring 213 in case of deflection.

[0067] As shown in FIG. 3, the inner circumferential surface of one of the first valve seat 120 and the second valve seat 130 is in a guiding fit with the outer circumferential surface of the first valve sleeve 212, and a first gap is formed between the inner circumferential surface and the outer circumferential surface; the inner circumferential surface of the other one is in a second gap with the outer circumferential surface of the first valve sleeve 212; the first gap is smaller than the second gap.

[0068] For example, the inner circumferential surface of the first valve seat 120 is in a second gap with the outer circumferential surface of the first valve sleeve 212; the inner circumferential surface of the second valve seat 130 is in a guiding fit with the outer circumferential surface of the first valve sleeve 212, and a first gap is formed between the inner circumferential surface and the outer circumferential surface.

[0069] Of course, in other embodiments, the inner circumferential surface of the first valve seat 120 can be in a guiding fit with the outer circumferential surface of the first valve sleeve 212, and the inner circumferential surface of the second valve seat 130 can be in a second gap with the outer circumferential surface of the first valve sleeve 212.

[0070] Therefore, only the inner circumferential surface of one of the valve seats in the valve seat assembly 100 is in a small-gap guiding fit with the outer circumferential surface of the first valve sleeve 212, and the inner circumferential surfaces of the remaining valve seats maintain a larger gap fit, so that the valve core assembly 200 can avoid being stuck during movement when the inner circumferential surfaces of the valve seat assembly 100 are all designed to be in a guiding fit.

[0071] As shown in FIG. 6, one of the valve needle 211 and the first valve sleeve 212 has a connecting hole 212a, and the other one has a connecting shaft 211a inserted into the connecting hole 212a. At least part of the first elastic member 230 is located in the connecting hole 212a and can be abutted by the connecting shaft 211a. When the axial dimension of the connecting shaft 211a inserted into the connecting hole 212a is less than or equal to the first target value, the first elastic member 230 is in an original length state.

[0072] It can be understood that, in order to improve the sealing performance of the valve core assembly in plugging the valve port, the electronic expansion valve in the related art is often provided with a pre-tightening spring. When the valve core assembly plugs the valve port, the pre-tightening spring provides a pre-tightening force to make the valve core assembly tightly plug the valve port. However, after the pre-tightening spring is added, the valve core assembly is inconvenient to install and has a low installation efficiency.

[0073] Therefore, the valve core assembly 200 of the embodiment of the present disclosure is assembled by first inserting the second valve core 220 and the screw rod 300 into the first valve sleeve 212, then inserting the first elastic member 230 into the first valve sleeve 212, and finally connecting the valve needle 211 and the first valve sleeve 212 to seal the first elastic member 230 in the first valve sleeve 212. When the valve needle 211 and the first valve sleeve 212 are connected, the connecting shaft 211a is inserted into the connecting hole 212a. When the axial dimension of the connecting shaft 211a inserted into the connecting hole 212a is less than or equal to the first target value, the first elastic member 230 is in the original length state. On the one hand, the inner wall surface of the connecting hole 212a can play a guiding role to guide the insertion of the connecting shaft 211a into the connecting hole 212a. On the other hand, since the first elastic member 230 is in the original length state when the axial dimension of the connecting shaft 211a inserted into the connecting hole 212a is less than or equal to the first target value, the first elastic member 230 does not generate an elastic force at this time. That is, in the initial stage of the insertion of the connecting shaft 211a into the connecting hole 212a, the connecting shaft 211a will not be subjected to the reaction force provided by the first elastic force, thereby improving the smoothness of the insertion of the connecting shaft 211a into the connecting hole 212a and further improving the assembly efficiency.

[0074] In an embodiment, the first target value is greater than or equal to 0.5 mm, but is not limited thereto.

[0075] When the connecting shaft 211a and the connecting hole 212a are in interference fit, one end of the first elastic member 230 abuts against the second valve core 220, and the other end abuts against the connecting shaft 211a.

[0076] In an embodiment, the valve needle 211 has a connecting shaft 211a, and the first valve sleeve 212 has a connecting hole 212a. Of course, in other embodiments, the valve needle 211 has a connecting hole 212a, and the first valve sleeve 212 has a connecting shaft 211a.

[0077] Next, an example in which the valve needle 211 has a connecting shaft 211a and the first valve sleeve 212 has a connecting hole 212a is described.

[0078] As shown in FIG. 6, one of the outer peripheral surface of the connecting shaft 211a and the inner wall surface of the connecting hole 212a has a stepped surface, and the other has a surface in clearance fit or interference fit with the stepped surface.

[0079] In an embodiment, the connecting shaft 211a has a first fitting section 2113 and a second fitting section 2114. The first fitting section 2113 and the second fitting section 2114 are arranged along the axial direction of the connecting shaft 211a and form a stepped surface. The first fitting section 2113 is used to be in clearance fit with the inner wall surface of the connecting hole 212a, and the second fitting section 2114 is used to be in interference fit with the inner wall surface of the connecting hole 212a.

[0080] When the axial dimension of the connecting shaft 211a inserted into the connecting hole 212a is less than or equal to the first target value, at least part of the first matching section 2113 is located in the connecting hole 212a, and the first matching section 2113 is in clearance fit with the inner wall of the connecting hole 212a. When the axial dimension of the connecting shaft 211a inserted into the connecting hole 212a is greater than the first target value, the first matching section 2113 is entirely located in the connecting hole 212a, the first matching section 2113 is in clearance fit with the inner wall of the connecting hole 212a, at least part of the second matching section 2114 is located in the connecting hole 212a, and the second matching section 2114 is in interference fit with the inner wall of the connecting hole 212a.

[0081] In another embodiment, the inner wall surface of the connecting hole 212a has a stepped surface, and the outer peripheral surface of the connecting shaft 211a has a surface that is in clearance fit first and then in interference fit with the stepped surface.

[0082] As shown in FIG. 6, the valve needle 211 further has a fourth stop portion 2115 for stopping the other one of the first component and the second component when the connecting shaft 211a is in interference fit with the connecting hole 212a and the axial dimension of the portion of the connecting shaft 211a inserted into the connecting hole 212a reaches a second target value; wherein the second target value is greater than the first target value. By providing the fourth stop portion 2115 on the valve needle 211, it can be prevented that the dimension of the connecting shaft 211a inserted into the connecting hole 212a is too long to cause inconvenience in disassembly when the valve needle 211 and the first valve sleeve 212 are assembled.

[0083] Of course, in other embodiments, when the valve needle 211 has the connecting hole 212a and the first valve sleeve 212 has the connecting shaft 211a, the fourth stop portion 2115 can be provided on the first valve sleeve 212.

[0084] In an embodiment, the fourth stop portion 2115 is an annular protrusion that surrounds the outer peripheral surface of the connecting shaft 211a and is used to abut against the peripheral edge of the connecting hole 212a.

[0085] In other embodiments, the fourth stop portion 2115 can include a plurality of sub-protrusions that are arranged along the circumference of the connecting shaft 211a.

[0086] As shown in FIGS. 2 and 3, the top of the valve cavity 110 has a back pressure cavity 111, and the valve core assembly 200 has a first balance passage 201 that communicates with the back pressure cavity 111 and the valve port 110a. The electronic expansion valve of the embodiments of the present disclosure further includes a guide structure 600 for guiding the movement of the valve core assembly 200 relative to the valve seat assembly 100; the guide structure 600 has a second balance passage 601 that communicates with the first balance passage 201 and the valve port 110a.

[0087] It can be understood that in the related art, due to the large fluid impact force of the refrigerant, the valve core assembly is prone to tilt after being impacted by the refrigerant and cannot be aligned with the valve port, thereby reducing the working reliability of the electronic expansion valve.

[0088] Therefore, in the embodiments of the present disclosure, the electronic expansion valve comprises a guide structure 600 for guiding the movement of the valve core assembly 200, which can effectively avoid the problem that the valve core assembly 200 is prone to tilt after being impacted by the fluid and cannot be aligned with the valve port. In addition, the valve core assembly 200 has a first balance channel 201 in communication with the back pressure cavity 111 and the valve port 110a, and the guide structure 600 has a second balance channel 601 in communication with the first balance channel 201 and the valve port 110a, so that the electronic expansion valve as a whole is an internal balance valve, thereby improving the opening and closing ability of the valve.

[0089] In the embodiments of the present disclosure, the valve needle 211 and the valve core seat 221 of the valve core assembly 200 have channels in communication with each other, and the valve core seat 221 has an opening in communication with the channel of the valve core seat 221. Each channel and opening together constitute the first balance channel 201.

[0090] As shown in FIGS. 2 and 3, the guide structure 600 comprises a connecting portion 610 and a guide portion 620. The connecting portion 610 is connected to the cavity wall of the valve cavity 110 and has the second balance channel 601; the guide portion 620 is connected to one of the connecting portion 610 and the valve core assembly 200 and guides the other one. In an embodiment, the connecting portion 610 has a plurality of second balance channels 601, and the plurality of second balance channels 601 are arranged along the circumference of the guide portion 620.

[0091] The guide portion 620 is a guide hole 621, and the guide hole 621 penetrates the connecting portion 610 along the axial direction of the electronic expansion valve; the valve needle 211 of the valve seat assembly 100 is arranged in the guide hole 621, and the outer circumferential surface of the valve needle 211 of the valve seat assembly 100 guides the hole wall of the guide hole 621.

[0092] As shown in FIGS. 7 and 8, the second embodiment of the present disclosure is the same as the first embodiment, and the differences are as follows:

[0093] The guide portion 620 comprises a first guide rod 622 and a guide column 623, one end of the first guide rod 622 is connected to the connecting portion 610, and the other end is connected to the guide column 623; the guide column 623 extends into the first balance channel 201, and the outer circumferential surface of the guide column 623 guides the inner wall surface of the first balance channel 201.

[0094] The outer periphery of the guide column 623 has a first tangent surface 623a, which extends through two first end surfaces 623b of the guide column 623 and forms a third balance passage 602 with the inner wall surface of the first balance passage 201. The first balance passage 201 communicates with the valve port through the third balance passage 602.

[0095] In another embodiment, the guide portion 620 includes a first guide rod 622 and a guide column 623. One end of the guide column 623 extends into the first balance passage 201 and is connected to the spool assembly 200, and the other end is connected to the first guide rod 622. The connecting portion 610 further has a guide hole 621 extending axially. The outer peripheral surface of the first guide rod 622 is guided by the hole wall of the guide hole 621.

[0096] As shown in FIGS. 9 and 10, the third embodiment of the present disclosure is the same as the first embodiment, and the differences are as follows:

[0097] The guide portion 620 includes a second guide rod 624, one end of which is connected to the connecting portion 610 and the other end of which extends into the first balance passage 201. The outer peripheral surface of the second guide rod 624 is guided by the inner wall surface of the first balance passage 201.

[0098] The outer periphery of the second guide rod 624 has a second tangent surface 624a, which extends to a second end surface 624b of the second guide rod 624 located in the first balance passage 201. The second tangent surface 624a forms a fourth balance passage 603 with the inner wall surface of the first balance passage 201. The first balance passage 201 communicates with the valve port through the fourth balance passage 603.

[0099] In an embodiment, the number of second tangent surfaces 624a is multiple, and the multiple second tangent surfaces 624a are arranged along the circumference of the second guide rod 624. Of course, in other embodiments, the number of second tangent surfaces 624a can also be one.

[0100] In another embodiment, the guide portion 620 includes a second guide rod 624, and the connecting portion 610 further has a guide hole 621 extending axially. One end of the second guide rod 624 extends into the first balance passage 201 and is connected to the spool assembly 200, and the other end is guided by the hole wall of the guide hole 621.

[0101] As shown in FIGS. 11 and 12, the fourth embodiment of the present disclosure is the same as the first embodiment, and the differences are as follows:

[0102] The second guide rod 624 has a fifth balance passage 604 inside, which extends through two second end surfaces 624b of the second guide rod 624. The first balance passage 201 communicates with the second balance passage 601 through the fifth balance passage 604.

[0103] As shown in FIG. 13, the fifth embodiment of the present disclosure has the same parts as the fourth embodiment, and the different parts are as follows:

[0104] The electronic expansion valve of the embodiments of the present disclosure further comprises a mounting seat 700, the mounting seat 700 has a mounting cavity 704, and at least part of the valve seat assembly 100 is inserted into the mounting cavity 704.

[0105] The mounting seat 700 further has an inlet 701, a first outlet 702 and a second outlet 703 which are in communication with the mounting cavity 704, the inlet 701 is in communication with the second opening 104 of the valve seat assembly 100, the first outlet 702 is in communication with the first opening 103 of the valve seat assembly 100, and the second outlet 703 is in communication with the third opening 105 of the valve seat assembly 100. The third opening 105 is arranged at the bottom of the third valve seat 150.

[0106] As shown in FIG. 14, the sixth embodiment of the present disclosure has the same parts as the fifth embodiment, and the different parts are as follows:

[0107] The length of the third valve seat 150 along the axial direction of the electronic expansion valve is greater than the axial length of the third valve seat 150 of the fifth embodiment, and the third opening 105 is arranged at the side of the third valve seat 150.

[0108] As shown in FIG. 15, the seventh embodiment of the present disclosure has the same parts as the fifth embodiment, and the different parts are as follows:

[0109] The electronic expansion valve does not have the guide structure 600.

[0110] It can be understood that the electronic expansion valve of the first embodiment to the fourth embodiment of the present disclosure can not be provided with the mounting seat 700, but the first opening 103, the second opening 104 and the third opening 105 are directly connected with the external connecting pipe.

[0111] In summary, the electronic expansion valve of the embodiments of the present disclosure has at least the following advantages and beneficial effects:

[0112] The electronic expansion valve provided by the embodiment of the present disclosure comprises a first elastic member 230 and a second elastic member 500, the first elastic member 230 is capable of applying a first pre-tightening force to the first valve core 210 to block the first valve port 101, and the second elastic member 500 is capable of applying a second pre-tightening force to the first valve core 210 to block the second valve port 102, so that the sealing performance of the first valve core 210 when blocking the first valve port 101 or the second valve port 102 is significantly improved, fluid leakage of the electronic expansion valve is prevented, and the working reliability is improved. In addition, the electronic expansion valve provided by the embodiment of the present disclosure, the screw rod 300 drives the first valve core 210 to move between the first position and the second position through the second valve core 220, and the first pre-tightening force provided by the first elastic member 230 acts on the first valve core 210 and the second valve core 220 respectively, and the second pre-tightening force provided by the second elastic member 500 acts on the screw rod 300 and the second valve core 220 respectively, so that the first pre-tightening force and the second pre-tightening force do not affect each other, and it is ensured that the first pre-tightening force and the second pre-tightening force are large enough, and the sealing performance of the first valve core 210 when blocking the first valve port 101 and the second valve port 102 is further improved.

[0113] When the axial dimension of the part of the connecting shaft 211a inserted into the connecting hole 212a is less than or equal to the first target value in the clearance fit state, the first elastic member 230 is in the original length state. On the one hand, the connecting shaft 211a and the connecting hole 212a are in the clearance fit state, and the inner wall surface of the connecting hole 212a can play a guiding role to guide the connecting shaft 211a to be inserted into the connecting hole 212a. On the other hand, since the axial dimension of the part of the connecting shaft 211a inserted into the connecting hole 212a is less than or equal to the first target value, the first elastic member 230 is in the original length state at this time, and the first elastic member 230 does not generate an elastic force. That is to say, in the initial stage of the connecting shaft 211a being inserted into the connecting hole 212a, the connecting shaft 211a will not be subjected to the reaction force provided by the first elastic force, the smoothness of the connecting shaft 211a being fitted into the connecting hole 212a is improved, and the assembly efficiency is further improved.

[0114] The electronic expansion valve provided by the embodiment of the present disclosure comprises a guide structure 600 for guiding the movement of the valve core assembly 200, which can effectively avoid the problem that the valve core assembly 200 is easily inclined and cannot be aligned with the valve port after being subjected to the fluid impact force. In addition, the valve core assembly 200 has a first balance channel 201 in communication with the back pressure cavity 111 and the valve port 110a, and the guide structure 600 has a second balance channel 601 in communication with the first balance channel 201 and the valve port 110a, so that the electronic expansion valve as a whole is an internal balance valve, and the opening and closing ability is improved.

[0115] It can be understood that the various embodiments / implementation modes provided by the present disclosure can be combined with each other without contradiction, and will not be illustrated one by one here.

[0116] In the disclosure embodiments, the terms "first", "second", "third" are used only for descriptive purposes, and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more, unless otherwise explicitly limited. The terms "mounting", "connecting", "connection", "fixing" and the like should be interpreted broadly, for example, "connection" can be fixed connection, or detachable connection, or integral connection; "connection" can be direct connection, or indirect connection through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the disclosure embodiments can be understood according to the specific circumstances.

[0117] In the description of the disclosure embodiments, it should be understood that the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the disclosure embodiments and simplify the description, and do not indicate or imply that the device or unit referred to must have a particular direction, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the disclosure embodiments.

[0118] In the description of the disclosure, the terms "one embodiment", "some embodiments", "specific embodiments" and the like mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the disclosure. In the description, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0119] The above is only the preferred embodiment of the disclosure, and is not intended to limit the disclosure. Those skilled in the art can make various modifications and changes to the disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the disclosure shall be included in the protection scope of the disclosure.

Claims

1. An electronic expansion valve, wherein, The valve seat assembly comprises a valve cavity, a cavity wall of the valve cavity having a first valve port and a second valve port arranged at an axial interval along the electronic expansion valve; The valve core assembly is arranged at least partially in the valve cavity and comprises a first valve core, a second valve core and a first elastic member, the first valve core being movable between a first position for blocking the first valve port and a second position for blocking the second valve port, the second valve core being used to drive the first valve core to move, the first elastic member being connected to the first valve core and the second valve core, the second valve core being capable of moving relative to the first valve core in a direction close to the first valve port to increase a compression amount of the first elastic member and to apply a first pre-tightening force for blocking the first valve port to the first valve core when the first valve core is located at the first position; A screw rod is used to drive the second valve core to move axially along the electronic expansion valve; and A second elastic member is connected to the second valve core and the screw rod, the screw rod being capable of moving relative to the first valve core in a direction away from the second valve port to increase a compression amount of the second elastic member and to apply a second pre-tightening force for blocking the second valve port to the first valve core through the second valve core when the first valve core is located at the second position. The first valve core comprises: A valve needle for blocking the first valve port or the second valve port; 2. The electronic expansion valve according to claim 1, wherein, A first valve sleeve fixedly connected with the valve needle; The first valve sleeve is limitingly connected with the second valve core to enable the first valve core to move from the first position to the second position. The part of the valve needle surrounded by the first valve sleeve has an end face; The inner circumferential surface of the first valve sleeve is provided with a first stopper arranged at an axial interval with the end face along the electronic expansion valve; 3. The electronic expansion valve of claim 2, wherein, The part of the second valve core extending into the first valve sleeve is provided with a flange, the flange moving between the first stopper and the end face to compress the first elastic member, the flange pulling the first stopper to enable the first valve core to move from the first position to the second position. The valve needle has a receiving groove recessed from the end face in a direction away from the second valve core along the electronic expansion valve; The first elastic member is accommodated in the receiving groove, one end of the first elastic member abutting against a groove bottom surface of the receiving groove and the other end abutting against the second valve core.

4. The electronic expansion valve of claim 3, wherein, The valve needle is in interference fit with the first valve sleeve. The part of the valve needle surrounded by the first valve sleeve has a first fitting section and a second fitting section, the first fitting section and the second fitting section being arranged along the electronic expansion valve in an axial direction, and the first fitting section being closer to the second valve core than the second fitting section; 5. The electronic expansion valve of claim 2, wherein, The first fitting section is in clearance fit with the inner circumferential surface of the first valve sleeve, and the second fitting section is in interference fit with the inner circumferential surface of the first valve sleeve.

6. The electronic expansion valve of claim 5, wherein, The valve seat assembly comprises a first valve seat and a second valve seat, the first valve seat and the second valve seat being fixedly connected and jointly enclosing at least part of the valve cavity; ​ 7. The electronic expansion valve of claim 2, wherein, ​ An inner circumferential surface of one of the first valve seat and the second valve seat is in a guiding fit with an outer circumferential surface of the first valve sleeve, and a first gap is formed between the inner circumferential surface and the outer circumferential surface; an inner circumferential surface of the other of the first valve seat and the second valve seat is in a guiding fit with an outer circumferential surface of the first valve sleeve, and a second gap is formed between the inner circumferential surface and the outer circumferential surface; the first gap is smaller than the second gap.

8. Electronic expansion valve according to any of claims 1 to 7, wherein The second valve core comprises: a valve core seat, at least a part of the valve core seat is arranged in the first valve core, and the valve core seat is used to pull the first valve core to move from the first position to the second position; and a second valve sleeve, the second valve sleeve is fixedly connected with the valve core seat; one end of the second elastic member and the screw rod is arranged in the second valve sleeve.

9. The electronic expansion valve of claim 8, wherein, An inner circumferential surface of the second valve sleeve has a second stop portion; The screw rod comprises a rod portion and a third stop portion, the third stop portion is connected to one end of the rod portion, and is arranged in the second valve sleeve and is movable between the second stop portion and the valve core seat; One end of the second elastic member abuts against the second stop portion, and the other end of the second elastic member abuts against the third stop portion.

10. The electronic expansion valve of claim 9, wherein, The third stop portion comprises: a bearing, an inner ring of the bearing is sleeved on an outer circumferential surface of the rod portion, and the bearing is fixedly connected with the rod portion; and a protection sheet, the protection sheet is arranged on a side of the bearing facing the second stop portion, and the other end of the second elastic member abuts against the protection sheet.

11. The electronic expansion valve of claim 1, wherein, A first inner sealing ring is further arranged between the valve core assembly and a cavity wall of the valve cavity, the first valve core is in a movable sealing fit with the cavity wall of the valve cavity through the first inner sealing ring, and a sealing position between the first valve core and the cavity wall of the valve cavity forms a first sealing ring; A sealing position between the first valve core and the first valve port forms a second sealing ring, and a sealing position between the first valve core and the second valve port forms a third sealing ring; A diameter of the second sealing ring is greater than a diameter of the first sealing ring, and a diameter of the third sealing ring is greater than the diameter of the first sealing ring.

12. The electronic expansion valve of claim 11, wherein, The valve seat assembly further comprises a first opening, a second opening and a third opening which are in communication with the valve cavity; along an axial direction of the electronic expansion valve, the first opening, the second valve port, the second opening, the first valve port and the third opening are arranged in sequence; the first opening and the second opening are respectively located on two sides of the first valve port, the second opening and the third opening are respectively located on two sides of the second valve port, and the second opening is located between the first valve port and the second valve port; The first pre-tightening force F1 satisfies: (π×D2 2 ÷4-π×D1 2 ÷4)×ΔP1<F1; wherein D2 is a diameter of the second sealing ring, D1 is a diameter of the first sealing ring, and ΔP1 is a fluid pressure difference between the third opening and the second opening when the electronic expansion valve is in communication with fluid; The second pre-tightening force F2 satisfies: (π x D3 2 ÷ 4 - π x D1 2 ÷ 4) x ΔP2 < F2; wherein D3 is a diameter of the third sealing ring, D1 is a diameter of the first sealing ring, and ΔP2 is a fluid pressure difference between the first opening and the second opening when the electronic expansion valve is in communication with fluid.

13. The electronic expansion valve of claim 1, wherein, A top portion of the valve cavity has a back pressure cavity; the valve core assembly has a first balance channel which is in communication with the back pressure cavity, the first valve port and the second valve port; and A guide structure for guiding movement of the valve plug assembly relative to the valve seat assembly; the guide structure having a second balance passage in communication with the first balance passage and the valve port.

14. The electronic expansion valve of claim 13, wherein, The guide structure comprises: a connecting portion connected to a cavity wall of the valve cavity and having the second balance passage; and a guide portion connected to one of the connecting portion and the valve plug assembly and guiding the other one.

15. The electronic expansion valve of claim 14, wherein, The guide portion is a guide hole penetrating the connecting portion along an axial direction of the electronic expansion valve; The valve plug assembly is arranged in the guide hole, and an outer circumferential surface of the valve plug assembly is guided by a hole wall of the guide hole.

16. The electronic expansion valve of claim 14, wherein, The guide portion comprises a first guide rod and a guide post, one end of the first guide rod is connected to the connecting portion, and the other end is connected to the guide post; the guide post extends into the first balance passage, and an outer circumferential surface of the guide post is guided by an inner wall surface of the first balance passage; Or, the guide portion comprises a first guide rod and a guide post; one end of the guide post extends into the first balance passage and is connected to the valve plug assembly, and the other end is connected to the first guide rod; the connecting portion further has a guide hole penetrating in an axial direction, and an outer circumferential surface of the first guide rod is guided by a hole wall of the guide hole.

17. The electronic expansion valve of claim 16, wherein, An outer circumference of the guide post has a first cutting surface, the first cutting surface penetrates two first end surfaces of the guide post, the first cutting surface and the inner wall surface of the first balance passage enclose a third balance passage, and the first balance passage communicates with the valve port through the third balance passage.

18. The electronic expansion valve of claim 14, wherein, The guide portion comprises a second guide rod, one end of the second guide rod is connected to the connecting portion, and the other end extends into the first balance passage; an outer circumferential surface of the second guide rod is guided by an inner wall surface of the first balance passage; Or, the guide portion comprises a second guide rod, and the connecting portion further has a guide hole penetrating in an axial direction; one end of the second guide rod extends into the first balance passage and is connected to the valve plug assembly, and the other end is guided by a hole wall of the guide hole.

19. The electronic expansion valve of claim 18, wherein, An outer circumference of the second guide rod has a second cutting surface; one end of the second cutting surface extends to a second end surface of the second guide rod located in the first balance passage; The second cutting surface and the inner wall surface of the first balance passage enclose a fourth balance passage, and the first balance passage communicates with the valve port through the fourth balance passage.

20. The electronic expansion valve of claim 19, wherein, The number of the second cutting surfaces is multiple, and the second cutting surfaces are arranged along a circumferential direction of the second guide rod.

21. The electronic expansion valve of claim 18, wherein, The second guide rod has a fifth balance passage inside, and the fifth balance passage penetrates two second end surfaces of the second guide rod; The first balance passage communicates with the second balance passage through the fifth balance passage.

22. The electronic expansion valve according to any one of claims 14 to 21, wherein, The connecting portion has multiple second balance passages, and the multiple second balance passages are arranged along a circumferential direction of the guide portion.

23. The electronic expansion valve of claim 1, wherein, The first valve plug comprises a valve needle, a first valve sleeve, and a first elastic member; One of the valve needle and the first valve sleeve has a connecting hole, and the other one has a connecting shaft for being inserted into the connecting hole; at least part of the first elastic member is located in the connecting hole and can be abutted by the connecting shaft; The first elastic member is in an original length state when the axial dimension of the connecting shaft inserted into the connecting hole is less than or equal to a first target value.

24. The electronic expansion valve of claim 23, wherein, The connecting shaft comprises a first fitting section, at least part of the first fitting section is located in the connecting hole when the axial dimension of the connecting shaft inserted into the connecting hole is less than or equal to the first target value, and the first fitting section is in clearance fit with the inner wall of the connecting hole.

25. The electronic expansion valve of claim 24, wherein, The connecting shaft further comprises a second fitting section forming a stepped surface with the first fitting section, the first fitting section is entirely located in the connecting hole, the first fitting section is in clearance fit with the inner wall of the connecting hole, at least part of the second fitting section is located in the connecting hole, and the second fitting section is in interference fit with the inner wall of the connecting hole when the axial dimension of the connecting shaft inserted into the connecting hole is greater than the first target value.

26. The electronic expansion valve of claim 23, wherein, One of the valve needle and the first valve sleeve further comprises a fourth stopper for stopping the other one of the valve needle and the first valve sleeve when the axial dimension of the connecting shaft inserted into the connecting hole reaches a second target value. The second target value is greater than the first target value.

27. The electronic expansion valve of claim 26, wherein, The fourth stopper is an annular protrusion surrounding the outer circumferential surface of the connecting shaft for abutting against the circumferential edge of the connecting hole.

28. The electronic expansion valve of claim 23, wherein, One end of the connecting shaft has an end surface. The connecting shaft further comprises a receiving groove recessed from the end surface along the axial direction of the connecting shaft to the other end of the connecting shaft. At least part of the first elastic member is located in the receiving groove.

29. The electronic expansion valve of claim 23, wherein, The first valve sleeve has the connecting hole, and the inner circumferential surface of the first valve sleeve protrudes with a first stopper spaced apart from the end surface of the connecting shaft along the axial direction of the connecting shaft. The portion of the second valve core extending into the first valve sleeve is provided with a flange located between the first stopper and the end surface for pressing the first elastic member or contacting the first stopper.

30. The electronic expansion valve of claim 29, wherein, One end of the first elastic member abuts against the second valve core and the other end abuts against the connecting shaft when the axial dimension of the connecting shaft inserted into the connecting hole is greater than or equal to the first target value.

31. The electronic expansion valve of claim 29, wherein, The second valve core comprises: a valve core seat, at least part of the valve core seat is located in the first valve sleeve, and the valve core seat is provided with the flange; and a second valve sleeve, one end of the second valve sleeve is fixedly connected with the valve core seat.

32. The electronic expansion valve of claim 1, wherein, The first valve core comprises: a valve needle provided with a limiting portion; a stop ring fixedly connected with the valve needle; and a second inner sealing ring clamped between the limiting portion and the stop ring.

33. The electronic expansion valve of claim 32, wherein, The valve needle further comprises a stepped structure, and the stop ring is in stop fit with the stepped structure. The first elastic member is in an original length state when the axial dimension of the connecting shaft inserted into the connecting hole is less than or equal to a first target value. The connecting shaft comprises a first fitting section, at least part of the first fitting section is located in the connecting hole when the axial dimension of the connecting shaft inserted into the connecting hole is less than or equal to the first target value, and the first fitting section is in clearance fit with the inner wall of the connecting hole. The connecting shaft further comprises a second fitting section forming a stepped surface with the first fitting section, the first fitting section is entirely located in the connecting hole, the first fitting section is in clearance fit with the inner wall of the connecting hole, at least part of the second fitting section is located in the connecting hole, and the second fitting section is in interference fit with the inner wall of the connecting hole when the axial dimension of the connecting shaft inserted into the connecting hole is greater than the first target value. One of the valve needle and the first valve sleeve further comprises a fourth stopper for stopping the other one of the valve needle and the first valve sleeve when the axial dimension of the connecting shaft inserted into the connecting hole reaches a second target value. The second target value is greater than the first target value. The fourth stopper is an annular protrusion surrounding the outer circumferential surface of the connecting shaft for abutting against the circumferential edge of the connecting hole. One end of the connecting shaft has an end surface. The connecting shaft further comprises a receiving groove recessed from the end surface along the axial direction of the connecting shaft to the other end of the connecting shaft. At least part of the first elastic member is located in the receiving groove. The first valve sleeve has the connecting hole, and the inner circumferential surface of the first valve sleeve protrudes with a first stopper spaced apart from the end surface of the connecting shaft along the axial direction of the connecting shaft. The portion of the second valve core extending into the first valve sleeve is provided with a flange located between the first stopper and the end surface for pressing the first elastic member or contacting the first stopper. One end of the first elastic member abuts against the second valve core and the other end abuts against the connecting shaft when the axial dimension of the connecting shaft inserted into the connecting hole is greater than or equal to the first target value. The second valve core comprises: a valve core seat, at least part of the valve core seat is located in the first valve sleeve, and the valve core seat is provided with the flange; and a second valve sleeve, one end of the second valve sleeve is fixedly connected with the valve core seat. The first valve core comprises: a valve needle provided with a limiting portion; a stop ring fixedly connected with the valve needle; and a second inner sealing ring clamped between the limiting portion and the stop ring. The valve needle further comprises a stepped structure, and the stop ring is in stop fit with the stepped structure.

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