Conical filter screen with spiral flow guide function and electronic expansion valve

Abstract

The invention provides a conical filter screen with a spiral diversion function and an electronic expansion valve, the conical filter screen comprises a filter screen body, one end of the filter screen body is provided with a conical groove, the other end of the filter screen body is provided with a conical diversion surface, and the conical tip of the conical groove and the conical tip of the conical diversion surface both face the same direction. The conical flow guide surface is provided with a spiral flow guide structure. A refrigerant is guided to flow through the conical flow guide face of the spiral flow guide structure, so that the refrigerant is evenly dispersed to pass through the filter screen body along a spiral path, generation of vortexes is restrained, and flow noise and energy loss are reduced. The two connecting pipes of the electronic expansion valve are internally provided with the filter screens with the conical tips facing the opposite directions respectively, so that one filter screen faces a refrigerant with the conical tip under the refrigerating and heating working conditions, and vortex noise is further restrained in cooperation with a spiral flow guide structure.

Description

Technical Field

[0001] This invention belongs to the field of electronic expansion valve technology, specifically relating to a conical filter screen with spiral flow guiding function and an electronic expansion valve. Background Technology

[0002] The electronic expansion valve is the core throttling element of the refrigeration system. Its internal filter screen is usually installed in the valve body flow channel to filter impurity particles in the refrigerant, prevent impurities from clogging the valve port or damaging the valve core, and ensure the long-term stable operation of the electronic expansion valve.

[0003] Existing electronic expansion valves typically use flat plate filters, ordinary single-cone filters, or cylindrical filters. These filters are usually made of woven metal wire mesh or sintered stainless steel powder metallurgy, and can achieve basic filtration functions. However, the installation of existing filters usually requires pipe reduction to create a limiting step to fix the filter. All of these filters have certain drawbacks: the effective filtration area of ​​flat plate filters is limited by the pipe cross-sectional area, leading to excessively high refrigerant flow velocity and increased resistance; while ordinary conical filters increase the filtration area to some extent, their outer surface is mostly a smooth cone, lacking a flow-guiding structure, making it easy for eddies and energy loss to occur when refrigerant flows through the filter. Furthermore, electronic expansion valves need to withstand bidirectional refrigerant flow in both cooling and heating modes, while existing filters are mostly only suitable for unidirectional flow. When refrigerant flows in the opposite direction through the filter, it easily generates significant eddy noise, affecting the user experience. Furthermore, some filters use a multi-piece or composite layer structure with seams, which can easily crack or fall off under long-term refrigerant impact and temperature changes, leading to filter failure.

[0004] To address the above problems, there is an urgent need to develop a new type of filter structure. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the above shortcomings, the present invention provides a conical filter screen with spiral flow guiding function and an electronic expansion valve, which solves the technical problems of existing filter screens requiring tube shrinking for installation, high flow resistance, high noise in bidirectional flow, and poor structural reliability.

[0006] Technical Solution: To achieve the above objectives, this invention provides a conical filter screen with a spiral flow guiding function, comprising a filter screen body. The filter screen body includes a conical groove at one end and a conical flow guiding surface at the other end, with the tips of the conical groove and the conical flow guiding surface both facing the same direction. The conical flow guiding surface has a spiral flow guiding structure. This invention is used in electronic expansion valves. When refrigerant flows into the electronic expansion valve through a pipe, it flows in from the conical flow guiding surface with the spiral flow guiding structure and flows out from the conical groove. When the refrigerant flows in, the spiral flow guiding structure on the conical flow guiding surface actively guides the refrigerant flow, causing the refrigerant to be evenly dispersed along a spiral path through the filter screen body, suppressing the generation of eddies, and reducing flow noise and energy loss.

[0007] Furthermore, in the aforementioned conical filter with spiral flow guiding function, the spiral flow guiding structure consists of spiral protrusions extending continuously along the conical flow guiding surface. These spiral protrusions guide the refrigerant flowing across the filter surface, creating a spiral flow path and preventing direct impact on the filter surface that could cause eddies and energy loss, thus reducing flow resistance. Additionally, the guidance of the continuously extending spiral protrusions reduces noise.

[0008] Furthermore, in the aforementioned conical filter with spiral flow guiding function, in order to ensure the flow guiding effect and avoid increasing flow resistance due to excessively steep angles, the included angle between the spiral flow guiding structure and the central axis of the filter body is 20°-25°.

[0009] Furthermore, in the aforementioned conical filter with spiral flow guiding function, the cone angle of the conical guide surface is 30°-60°. This cone angle range allows for a larger filtration area while maintaining structural strength, avoiding insufficient filtration area due to an excessively small cone angle or installation difficulties due to an excessively large cone angle.

[0010] Furthermore, in the aforementioned conical filter with spiral flow guiding function, in order to ensure a larger filtration area and reduce refrigerant flow resistance, the generatrix length of the conical groove and the conical flow guiding surface is greater than its cone bottom radius, so that the effective filtration area is greater than the area of ​​a circular plane with the same bottom diameter.

[0011] Furthermore, in the aforementioned conical filter with spiral flow guiding function, the filter body is a one-piece structure without seams or composite layers, and filter pores are distributed on it. The one-piece structure eliminates stress concentration and failure risk at seams, thus improving the service life of the filter.

[0012] Furthermore, in the aforementioned conical filter with spiral flow guiding function, the filter pore size is 80-120 mesh. This mesh size range balances filtration accuracy and flow capacity, effectively filtering impurities ≥0.15mm while ensuring sufficient refrigerant throughput. Furthermore, in the aforementioned conical filter with spiral flow guiding function, the maximum outer diameter of the filter body is 6.0mm-7.0mm, which is used to adapt to pipes with an outer diameter of 8mm.

[0013] An electronic expansion valve includes a valve body with a first connecting pipe and a second connecting pipe, each having a flow channel for refrigerant circulation. A first filter screen and a second filter screen are respectively installed in the first and second connecting pipes, both of which are the aforementioned conical filter screens with spiral flow guiding function.

[0014] Furthermore, in the aforementioned electronic expansion valve, the cone tip of the first filter screen faces the inlet of the first connecting pipe, and the cone tip of the second filter screen faces the inlet of the second connecting pipe, making the cone tips of the first and second filter screens face opposite directions. Since the refrigerant flows in opposite directions in cooling and heating modes, the symmetrical arrangement of the first and second filter screens with opposite cone tips ensures that regardless of whether the refrigerant flows in from the first or second connecting pipe, it first passes through the spiral flow guiding structure on the conical guide surface for guidance, and then flows out through the conical groove of the filter body. This bidirectional adaptability structure enables the electronic expansion valve to maintain stable operation with low flow resistance and low noise in both cooling and heating modes, eliminating the need to replace or adjust the filter screen due to changes in flow direction, thus improving the product's applicability and reliability.

[0015] As can be seen from the above technical solution, the present invention has the following beneficial effects: ① This invention features a conical filter screen with a spiral flow guiding function. Its conical structure, combined with the spiral flow guiding surface, causes the refrigerant to flow in a spiral pattern as it passes through the filter screen, reducing eddies and energy loss. The geometric feature that the generatrix length of the conical surface is greater than the radius of the conical base significantly increases the effective filtration area and reduces flow resistance.

[0016] ② The filter body is designed as a seamless, one-piece structure without any composite layers, eliminating stress concentration and the risk of detachment at the joints. It is less prone to cracking under refrigerant impact and temperature changes, resulting in a long service life. The filter mesh size is set at 80-120 mesh, effectively filtering impurities ≥0.15mm, protecting the valve core and valve port, while ensuring sufficient refrigerant throughput and avoiding excessive flow resistance due to overly fine filtration.

[0017] ③The electronic expansion valve of the present invention has filters installed in the two connecting pipes of the electronic expansion valve, and the cone tips of the two filters face opposite directions, so that in both cooling and heating bidirectional flow conditions, there is a filter with its cone tip facing the refrigerant. Combined with the spiral flow guiding structure, it further suppresses eddy noise. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the conical filter screen with spiral flow guiding function of the present invention; Figure 2 This is a schematic diagram of the electronic expansion valve of the present invention; Figure 3 This is a top view of the electronic expansion valve of the present invention; Figure 4 for Figure 3 The sectional view shown is along line AA.

[0019] In the diagram: 1. Filter screen body; 11. Conical groove; 12. Conical guide surface; 121. Spiral guide structure; 13. Filter pores. 2. Valve body; 21. First connecting pipe; 22. Second connecting pipe; 23. First filter screen; 24. Second filter screen. Detailed Implementation

[0020] Example 1 like Figure 1 The diagram illustrates a conical filter screen with a spiral flow guiding function. The filter screen body 1 includes an inwardly recessed conical groove 11 at one end and an outwardly protruding conical flow guiding surface 12 at the other end. The bottom tip of the conical groove 11 and the cone tip of the conical flow guiding surface 12 both face the same direction. Preferably, the inner conical surface of the conical groove 11 is parallel to the conical flow guiding surface 12, ensuring uniform wall thickness of the filter screen body 1 and guaranteeing structural strength. The conical flow guiding surface 12 is provided with a spiral flow guiding structure 121. This invention is used in electronic expansion valves. When refrigerant flows into the electronic expansion valve through a pipe, it flows in from the conical flow guiding surface 12 with the spiral flow guiding structure 121 and flows out from the conical groove 11. When refrigerant flows in, the spiral flow guiding structure 121 on the conical flow guiding surface 12 actively guides the refrigerant flow, causing the refrigerant to be evenly dispersed along a spiral path through the filter screen body 1, suppressing the generation of eddies, and reducing flow noise and energy loss.

[0021] As a further preferred embodiment, the spiral guide structure 121 is a spiral protrusion that extends continuously along the conical guide surface 12. The spiral protrusion structure can guide the refrigerant flowing across the filter surface, causing the refrigerant to form a spiral flow path, avoiding direct impact of the refrigerant on the filter surface to generate eddies and energy loss, and reducing flow resistance. Furthermore, the guidance of the refrigerant through the continuously extending spiral protrusions can reduce noise.

[0022] As a further preferred embodiment, the angle between the spiral flow guiding structure 121 and the central axis of the filter body 1 is 22°.

[0023] As a further preferred embodiment, the cone tip angle of the conical guide surface 12 is 45°. The overall height of the filter body 1 is 13.5 mm, and the wall thickness is 1.1 mm. As a further preferred embodiment, to ensure a larger filtration area and reduce refrigerant flow resistance, the generatrix length of the conical groove 11 and the conical guide surface 12 is greater than their cone base radius, making the effective filtration area larger than the area of ​​a circular plane with the same base diameter. Calculations show that in this embodiment, the ratio of the total effective pore area of ​​the single conical filter cone to the pore area of ​​a circular plane filter with the same maximum outer diameter is 4.7, which is within the preferred range of 4.5 to 5, thus improving the refrigerant throughput.

[0024] As a further preferred embodiment, the filter body 1 is a one-piece structure without seams or composite layers, and has filter pores 13 distributed on it. The filter pores 13 have a mesh size of 100 mesh. The filter body 1 is made of 150-180μm 316L water-atomized stainless steel powder, pre-pressed in a mold, and vacuum sintered at a sintering temperature of 1200℃ for 4 hours. After sintering, the filter body undergoes electrochemical passivation treatment, forming a dense Cr2O3 oxide film on the surface. The porosity after sintering is 38%, which can effectively filter impurities ≥0.15mm.

[0025] As a further preferred embodiment, the maximum outer diameter of the filter body 1 is 6.35mm ± 0.05mm, suitable for accommodating pipes with an 8mm outer diameter. The inner diameter of the 8mm outer diameter pipe is typically around 6.35mm, eliminating the need for pipe reduction during installation. Preferably, the pipe has inwardly protruding recesses for positioning the filter body 1.

[0026] like Figure 2-4 An electronic expansion valve is shown, comprising a valve body 2, which has a first connecting pipe 21 and a second connecting pipe 22, each containing a flow channel for refrigerant. A first filter screen 23 and a second filter screen 24 are respectively installed within the first connecting pipe 21 and the second connecting pipe 22. Both the first filter screen 23 and the second filter screen 24 are cone-shaped filters with a spiral flow guiding function, as described above. The first connecting pipe 21 and the second connecting pipe 22 are respectively pulsed laser welded to the first filter screen 23 and the second filter screen 24. After welding, the valve undergoes low-temperature stress relief treatment and is then coated with a 5-10 μm thin ceramic insulating coating.

[0027] Furthermore, in the aforementioned electronic expansion valve, the cone tip of the first filter screen faces the opening of the first connecting pipe 21, and the cone tip of the second filter screen faces the opening of the second connecting pipe 22, so that the cone tips of the first filter screen 23 and the second filter screen 24 face opposite directions.

[0028] The working principle of this invention is as follows: In cooling mode, refrigerant flows in from the inlet of the first connecting pipe 21, first contacting the conical guide surface 12 of the first filter screen 23. The spiral guide structure 121 guides the refrigerant to form a spiral flow, evenly dispersing it through the filter screen body 1, and then flowing out through the conical groove 11 before entering the throttling element inside the valve body 2. At this time, the cone tip of the second filter screen 24 faces the inlet of the second connecting pipe 22. If the refrigerant flows from the valve body 2 to the second connecting pipe 22, it first passes through the conical groove 11 of the second filter screen 24, and then flows out from the conical guide surface 12, maintaining smooth flow.

[0029] In heating mode, the refrigerant flow is reversed, flowing in from the inlet of the second connecting pipe 22. The second filter 24 plays a major guiding and filtering role, with its conical guide surface 12 facing the direction of refrigerant flow and the spiral guide structure 121 guiding the refrigerant in a spiral manner. The first filter 23 adapts to the reverse flow. Regardless of whether it is cooling or heating mode, both filters can ensure that the refrigerant passes through in a low-resistance, low-noise manner and effectively filters impurities.

[0030] Tests showed that, under both cooling and heating conditions, the pressure drop of the refrigerant flowing through the filter screen of this embodiment was reduced by about 35% compared to that of a traditional flat plate filter screen, and the noise was reduced by about 8dB. After 100,000 start-stop cycles in a temperature cycling test from -40℃ to 120℃, the filter screen body 1 showed no cracking or detachment, and the filtration performance remained stable.

[0031] Example 2 The main difference between this embodiment and Embodiment 1 is that the filter pore size 13 is 80 mesh, the angle between the spiral guide structure 121 and the central axis of the filter body 1 is 20°, and the cone tip angle of the conical guide surface 12 is 30°. The first connecting pipe 21 and the second connecting pipe 22 are respectively connected to the first filter screen 23 and the second filter screen 24 by low-temperature silver brazing, and the brazing filler metal is BAg-30. After welding, they should be subjected to low-temperature stress relief treatment and chemical nickel plating treatment with a thickness of 8-12μm.

[0032] Tests showed that the refrigerant flow resistance of the electronic expansion valve in this embodiment is reduced by 15% compared to ordinary single-cone filters, and the eddy current noise is reduced by 3dB(A).

[0033] Example 3 The filter pores 13 have a mesh size of 120, the spiral guide structure 121 has an angle of 25° with the central axis of the filter body 1, and the cone tip angle of the conical guide surface 12 is 60°.

[0034] Tests showed that the refrigerant flow resistance of the electronic expansion valve in this embodiment is reduced by 25% compared to ordinary single-cone filter screens, and the eddy current noise is reduced by 8dB(A).

[0035] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A conical filter screen with spiral flow guiding function, characterized in that: The filter body (1) includes a tapered groove (11) at one end and a tapered guide surface (12) at the other end. The tips of the tapered groove (11) and the tapered guide surface (12) are both facing the same direction. The tapered guide surface (12) is provided with a spiral guide structure (121).

2. The conical filter screen with spiral flow guiding function according to claim 1, characterized in that: The spiral guide structure (121) is a spiral protrusion that extends continuously along the conical guide surface (12).

3. The conical filter screen with spiral flow guiding function according to claim 2, characterized in that: The angle between the spiral flow guiding structure (121) and the central axis of the filter body (1) is 20°-25°.

4. The conical filter screen with spiral flow guiding function according to claim 1, characterized in that: The cone tip angle of the conical guide surface (12) is 30°-60°.

5. The conical filter screen with spiral flow guiding function according to claim 1, characterized in that: The generatrix length of the conical groove (11) and the conical guide surface (12) is greater than the radius of its cone bottom, so that the effective filtration area is greater than the area of ​​a circular plane with the same bottom diameter.

6. The conical filter screen with spiral flow guiding function according to claim 1, characterized in that: The filter body (1) is an integral structure without splicing seams or composite layers, and filter pores (13) are distributed on it.

7. The conical filter screen with spiral flow guiding function according to claim 6, characterized in that: The filter pore size (13) is 80-120 mesh.

8. The conical filter screen with spiral flow guiding function according to claim 1, characterized in that: The maximum outer diameter of the filter body (1) is 6.0mm-7.0mm, which is used to adapt to pipes with an outer diameter of 8mm.

9. An electronic expansion valve, characterized in that: The device includes a valve body (2), which has a first connecting pipe (21) and a second connecting pipe (22). The first connecting pipe (21) and the second connecting pipe (22) each have a flow channel for refrigerant to flow through. The first connecting pipe (21) and the second connecting pipe (22) are respectively provided with a first filter screen (23) and a second filter screen (24). The first filter screen (23) and the second filter screen (24) are both conical filter screens with spiral flow guiding function as described in any one of claims 1 to 8.

10. The electronic expansion valve according to claim 9, characterized in that: The cone tip of the first filter screen faces the opening of the first connecting pipe (21), and the cone tip of the second filter screen faces the opening of the second connecting pipe (22), so that the cone tips of the first filter screen (23) and the second filter screen (24) face opposite directions.

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