Expansion valve driven by shape memory alloy

Abstract

The invention discloses an expansion valve driven by shape memory alloy. The expansion valve comprises a sleeve-shaped shell, a memory alloy wire, a reset spring, a valve element, a valve seat and the like. The memory alloy wire shrinks through current heating, the valve element is pulled to open the valve, and the reset spring enables the valve element to reset and be closed after power failure. The valve element is of a missile-shaped structure and is provided with a pressure balance hole, the periphery of the valve element is provided with a movable sealing piece, liquid-phase refrigerants are prevented from entering a cavity above the valve element, it is guaranteed that the memory alloy wire is only in contact with gas-phase fluid, interference of the liquid-phase fluid is avoided, and working stability is guaranteed. The shape memory alloy wire is adopted as a driving element, the response speed is high, the problems of out-of-step and hysteresis of a traditional electric expansion valve are solved, the structure is compact, cost is low, power consumption is small, adaptability is high, rapid opening and closing and accurate opening adjustment can be achieved, the transient working condition requirement of a system is met, and the electric expansion valve is suitable for a new energy automobile thermal management system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valves, in particular to an expansion valve driven by a shape memory alloy. BACKGROUND

[0002] New energy vehicles, as an important direction of the transformation of the automobile industry, are accelerating the replacement of traditional fuel vehicles with their high energy efficiency, environmental friendliness, and intelligent control advantages. Under the impetus of the rapid development of the electric vehicle industry, the vehicle thermal management system has undergone significant architectural upgrades, with the innovation of expansion valve technology as the core flow regulating device being particularly critical. Modern thermal management systems generally use electronic expansion valves to achieve precise control of refrigerant flow, which not only improves energy utilization efficiency, but also promotes the development of thermal management systems towards intelligentization.

[0003] With the iteration of electric vehicle technology, electronic expansion valves face multi-dimensional performance upgrade demands: first, the dynamic response speed and control accuracy need to be improved to meet the rapid temperature adjustment requirements under transient operating conditions; second, under the trend of system integration, components need to evolve towards compactness; and third, cost optimization needs to be achieved through mass production and process innovation to enhance market competitiveness.

[0004] Current mainstream technical solutions have significant limitations: valve bodies driven by stepper motors have response hysteresis and out-of-step risks, resulting in a deviation of up to 10% between actual opening and target value; and electromagnetic drive solutions are limited by the size of electromagnetic components, which is not conducive to system lightweight. Developing new driving methods has become a technical bottleneck that the industry urgently needs to break through.

[0005] To solve the above problems, researchers have applied memory alloy technology to electronic expansion mechanisms, reducing the size of the expansion valve and saving overall costs. For example, patent WO 2014 / 202369 provides a valve embodiment based on a memory alloy actuator. However, the defect of the above patent is that the working fluid enters the working cavity and directly contacts the memory alloy, and the temperature change of the working fluid will have a significant impact on the state and deformation of the memory alloy material. If the working fluid is volatile, when the memory alloy wire is heated to a temperature exceeding the boiling point of the fluid, the working fluid will rapidly boil and absorb the heat of the memory alloy wire, making it difficult to control the temperature of the memory alloy wire, and in severe cases, causing the valve to fail. SUMMARY

[0006] The present application aims to provide an expansion valve driven by a shape memory alloy to solve the problems of slow response speed, low control accuracy, large size, and high cost in existing technologies.

[0007] To achieve the above object, the present application provides the following technical scheme: an expansion valve driven by a shape memory alloy, comprising: a sleeve-shaped shell, a memory alloy wire and a return spring; the sleeve-shaped shell is provided with a support at the top end, the sleeve-shaped shell is fixedly connected with a valve seat at the bottom end, and the sleeve-shaped shell is internally provided with a valve core; the support is made of an insulating material, a pair of terminal posts are fixedly connected in the support, and the free ends of the terminal posts pass through the top end of the support; the valve seat is provided with a circular hole around the valve seat, the valve seat is vertically provided with a through outlet channel, the outlet channel is communicated with the circular hole, the circular hole allows working fluid to enter, and the outlet channel is used for working fluid to flow out; the valve core is in a missile type structure, the valve core is sealingly and slidingly connected in the outlet channel at the bottom end, a vertical slot is formed in the middle of the valve core, a limit pin is arranged in the vertical slot, and a pressure balance hole is formed at the bottom end of the valve core; the memory alloy wire is fixedly connected with the terminal posts at both ends, and the lower part of the memory alloy wire is wound on the limit pin; and the return spring is arranged between the support and the valve core.

[0008] Preferably, the material of the memory alloy wire is a nickel-titanium alloy, which can change the heat generation and temperature by the internal current condition, and then change the shrinkage amount.

[0009] Preferably, a dynamic sealing member is arranged around the valve core, which is used for preventing liquid-phase refrigerant at the inlet from entering the cavity above the valve core.

[0010] Preferably, a guide structure is arranged on the inner wall of the sleeve-shaped shell, which is used for guiding the valve core to move stably along the axial direction, and ensuring the reliable opening and closing of the valve.

[0011] Preferably, a through hole is arranged around the sleeve-shaped shell, which allows working fluid to flow into the inside of the shell.

[0012] Preferably, a control unit electrically connected with the terminal posts is further included, the control unit is used for adjusting the current size of the memory alloy wire according to the system requirement, so as to realize the accurate opening degree control of the valve.

[0013] The principle and beneficial effects of the technical scheme are as follows:

[0014] The expansion valve of the present application adopts a shape memory alloy wire as a driving element, changes the temperature and shrinkage amount of the alloy wire by current excitation, and then drives the valve core to move to realize the opening and closing of the valve. The memory alloy wire is fixed on the terminal posts of the insulating support at both ends, and the lower part is wound on the limit pin of the valve core. When heated by electricity, the alloy wire shrinks to pull the valve core to open the valve; after power-off, the return spring resets the valve core to close the valve. The valve core adopts a missile type structure and is provided with a pressure balance hole, which ensures that the pressure of the valve core is balanced, and only subjected to the tension of the alloy wire and the spring force. In addition, a dynamic sealing member is arranged around the valve core, which prevents the liquid-phase refrigerant from entering the cavity above the valve core, so that the alloy wire only contacts with the gas-phase fluid, and the interference of the liquid-phase fluid is avoided.

[0015] The driving mode of the shape memory alloy wire has fast response speed, no out-of-step and hysteresis problems of traditional electric expansion valves, can realize fast opening and closing and precise opening degree adjustment, and meets the temperature adjustment demand under a transient working condition of the system. The memory alloy wire is used as the driving element, the mechanical structure is simplified, the number of parts is reduced, the overall volume and weight are reduced, the integration and light weight level of the automobile thermal management system are improved, and the production cost is reduced. The driving mode of the heated memory alloy wire has low power consumption, compared with the stepping motor and electromagnetic coil driving scheme, the energy consumption of the thermal management system is reduced, and the energy utilization rate of the whole vehicle is improved. The inner balance type structure design ensures that the memory alloy wire is not in direct contact with the liquid phase fluid, avoids boiling heat absorption of the volatile fluid medium on the surface of the alloy wire, ensures that the temperature and elongation control of the alloy wire during work is more stable and reliable, and prolongs the service life. The current size of the memory alloy wire is adjusted by the control unit, the valve opening degree can be flexibly adjusted according to the system demand, different working conditions and application scenes are adapted, and the intelligent level of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is a sectional view of the expansion valve in a closed state of the present application;

[0017] Fig. 2 is a sectional view of the expansion valve in an open state of the present application;

[0018] Fig. 3 is a local enlarged view of the valve port part of the expansion valve in an open state of the present application;

[0019] In the figure: 1, terminal post; 2, supporting piece; 3, memory alloy wire; 4, reset spring; 5, sleeve-shaped shell; 6, valve core; 61, pressure balance hole; 7, dynamic sealing piece; 8, valve seat. DETAILED DESCRIPTION

[0020] The present application will be further described in detail below in combination with the drawings and embodiments:

[0021] As Figs. 1-3The structure of the expansion valve driven by shape memory alloy includes terminal 1, support 2, memory alloy wire 3, reset spring 4, sleeve-shaped housing 5, valve core 6, dynamic seal 7, valve seat 8 and other components. The valve core 6 is a missile-shaped structure with a vertical slot in the middle to allow the memory alloy wire 3 to pass through its interior and is provided with a pressure balance hole 61. The memory alloy wire 3 is bent into a U shape as shown in the figure, both ends of which are fixedly connected with the terminal 1 and installed on the support 2 made of insulating material. The lower part of the memory alloy wire 3 is wound around a limit pin in the valve core 6. The sleeve-shaped housing 5 fixes the above-mentioned components in its interior. The valve seat 8 is provided with a circular hole in the circumferential direction to allow the working fluid to enter and is provided with an outlet channel at the bottom to allow the working fluid to flow out.

[0022] When the valve is not working, the reset spring 4 has a force to close the valve, drives the valve core 6 to contact the valve seat 8 and form a seal, and at the same time the memory alloy wire 3 is stretched to a certain length under the action of the spring force.

[0023] When the valve is working, a certain degree of current excitation is given to the terminal 1, the memory alloy wire 3 is heated by electricity, a shrinkage deformation occurs, and the limit pin is pulled to drive the valve core 6 to move towards the direction of opening the valve.

[0024] When the valve is working, the working fluid flows into the housing interior from the circumferential through hole of the sleeve-shaped housing 5 as shown by the solid arrow. When the valve core 6 is lifted, an annular fluid passage is formed between its lower end and the valve seat 7, the high-pressure liquid-phase working fluid passes through the annular passage to throttle and expand, and after expansion, it is a gas-liquid two-phase fluid, which flows out from the outlet channel at the bottom of the valve seat 8 as shown by the solid line arrow. Since the dynamic seal 5 is provided around the valve core 6, the liquid-phase refrigerant at the inlet will not enter the cavity above the valve core. Under the action of gravity, the liquid phase in the two-phase refrigerant after expansion is discharged, only the gas phase refrigerant can enter the cavity above the valve core 6 from the balance hole 61 as shown by the dotted line arrow. Since the dynamic seal 5 is provided around the valve core 6, the pressure at the upper and lower ends of the valve core 6 is the pressure after the working fluid expands, so the valve core 6 is subjected to equal fluid pressure at its upper and lower ends, and in theory, the valve core 6 is only subjected to the tension of the memory alloy wire 3 and the spring force of the reset spring 5. By adjusting the size of the current in the memory alloy wire 3, the heat generation and temperature of the memory alloy wire 3 can be changed, and the shrinkage amount of the memory alloy wire 3 can be changed, and under the joint action of the reset spring 5, the position control of the valve core 6 is realized, thereby realizing the opening degree adjustment of the valve. The above structure ensures that the memory alloy wire 3 does not contact the liquid-phase working fluid, but only contacts the gas-phase working fluid, avoids the boiling of volatile fluid medium on the surface of the memory alloy wire 3 to absorb heat, thereby ensuring that the temperature and elongation control of the memory alloy wire 3 is more stable and reliable.

[0025] The above are only embodiments of the present application, and common technical solutions or characteristics in the scheme are not described in detail. For those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the present application. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. An expansion valve driven by a shape memory alloy, characterized in that, include: The device comprises a sleeve-shaped housing, a shape memory alloy wire, and a return spring. A support member is located at the top of the sleeve-shaped housing, and a valve seat is fixedly connected to the bottom of the sleeve-shaped housing. A valve core is located inside the sleeve-shaped housing. The support member is made of insulating material and has a pair of terminals fixedly connected inside it, with the free ends of the terminals protruding from the top of the support member. The valve seat has circular holes around its perimeter and a vertically extending outlet channel that connects to the circular holes, allowing working fluid to enter and exit. The valve core has a missile-shaped structure, with its bottom sealed and slidably connected to the outlet channel. A vertical groove is formed in the middle of the valve core, containing a limit pin. A pressure balance hole is located at the bottom of the valve core. Both ends of the shape memory alloy wire are fixedly connected to the terminals, and the lower part of the wire is wound around the limit pin. The return spring is located between the support member and the valve core.

2. The expansion valve driven by a shape memory alloy according to claim 1, characterized in that: The shape memory alloy wire is made of nickel-titanium alloy, and its heat generation and temperature can be changed by the internal current, thereby changing its shrinkage.

3. An expansion valve driven by a shape memory alloy according to claim 1, characterized in that: A dynamic seal is provided around the valve core to prevent liquid refrigerant at the inlet from entering the cavity above the valve core.

4. An expansion valve driven by a shape memory alloy according to claim 1, characterized in that: The inner wall of the sleeve-shaped housing is provided with a guide structure to guide the valve core to move smoothly along the axial direction, ensuring reliable opening and closing of the valve.

5. An expansion valve driven by a shape memory alloy according to claim 1, characterized in that: The sleeve-shaped housing has a through hole in its circumference, allowing the working fluid to flow into the housing.

6. An expansion valve driven by a shape memory alloy according to claim 1, characterized in that: It also includes a control unit electrically connected to the terminal block, which is used to adjust the current of the shape memory wire according to system requirements in order to achieve precise valve opening control.

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