Thermostatic expansion valve and refrigeration system

Abstract

The utility model relates to a kind of thermal expansion valve and refrigeration system, the thermal expansion valve includes first membrane cover, copper base and valve body, first membrane cover has first surface, valve body has second surface, copper base is at least part of first surface by metallurgical structure lap joint, second surface is lap joint on the surface of copper base away from first membrane cover by solder layer.The thermal expansion valve has the advantages of excellent compactness, low cost and simple connection process.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration valve technology, and in particular to a thermostatic expansion valve and a refrigeration system. Background Technology

[0002] Traditional thermostatic expansion valves typically consist of a stainless steel lower diaphragm cap, a brass valve body, and a copper tube welded together. However, reliable fixing of the stainless steel lower diaphragm cap to the brass valve body requires high-silver-based solder (such as BAg40CuZnSn), which is costly and requires strict temperature control. Furthermore, the Cr-O oxide film on the surface of the stainless steel diaphragm at the welding location is difficult to decompose thermally, necessitating flux removal to ensure a good weld. This further increases the production cost and complicates the process. Therefore, there is an urgent need to develop more efficient, economical, and reliable thermostatic expansion valves. Utility Model Content

[0003] Therefore, it is necessary to provide a thermostatic expansion valve and its connection process and application to address the above problems. The thermostatic expansion valve has the advantages of excellent tightness, low cost and simple connection process.

[0004] This utility model discloses a thermal expansion valve, including a first diaphragm cover, a copper substrate, and a valve body. The first diaphragm cover has a first surface, and the valve body has a second surface. The copper substrate is overlapped with at least a portion of the first surface by a metallurgical structure, and the second surface is overlapped with the surface of the copper substrate opposite to the first diaphragm cover by a solder layer.

[0005] In one embodiment, the projected length of the copper substrate on the first membrane cover is a, and the projected length of the valve body on the first membrane cover is b, where a and b satisfy the following condition: a > b.

[0006] In one embodiment, the copper substrate is a copper-based binary alloy foil layer or a copper-based ternary alloy foil layer.

[0007] In one embodiment, the copper substrate is a CuSn alloy foil layer, a CuAg alloy foil layer, a CuSi alloy foil layer, a CuMn alloy foil layer, or a CuNi alloy foil layer.

[0008] In one embodiment, the thickness of the copper substrate is 0.01 mm to 0.2 mm.

[0009] In one embodiment, the copper substrate includes a folded portion.

[0010] In one embodiment, an element diffusion layer is provided between the copper substrate and the solder layer.

[0011] In one embodiment, the solder layer is a CuP-based solder layer.

[0012] In one embodiment, the first membrane cover is a stainless steel membrane cover; and / or, the thermal expansion valve further includes a copper tube overlapping at least a portion of the surface of the valve body.

[0013] A refrigeration system includes a thermostatic expansion valve as described above.

[0014] In the thermal expansion valve provided by this utility model, the copper substrate is fixed to the first diaphragm cover by forming a metallurgical structure with at least a portion of the first surface of the first diaphragm cover. The surface of the copper substrate facing away from the first diaphragm cover is welded to the second surface by a solder layer. Thus, the valve body, through the stacked copper substrate and solder layer, overlaps at least a portion of the first surface of the first diaphragm cover, effectively avoiding the risk of brittle phosphorus compounds forming when the solder layer contacts the first diaphragm cover, resulting in excellent tightness of the thermal expansion valve. Simultaneously, the welding of the first diaphragm cover to the valve body is transformed into welding of the copper substrate to the valve body. This material change eliminates the need for flux when using CuP-based solder, thus eliminating the subsequent flux cleaning process, reducing the production cost of the thermal expansion valve, and simplifying the process. Furthermore, it eliminates the need for high-silver-content AgCuZn-based solder, expanding the range of solder choices and allowing the use of lower-cost solders, such as CuP-based solders, further reducing the production cost of the thermal expansion valve. In addition, due to the expanded range of solder selection, there are also more welding methods available. For example, lower-cost welding methods such as flame welding or high-frequency welding can be used. As a result, the thermal expansion valve provided by this utility model has the advantages of low production cost, simple connection process, high density and high welding qualification rate.

[0015] Because the thermostatic expansion valve provided by this utility model has low production cost and simple connection process, the refrigeration system including the thermostatic expansion valve as described above has the advantages of both low production cost and simple process. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A cross-sectional schematic diagram of a thermostatic expansion valve according to one embodiment of the present invention.

[0018] Figure descriptions: 10, first membrane cover; 20, copper substrate; 30, solder layer; 301, brazing bevel; 40, valve body. Detailed Implementation

[0019] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0024] like Figure 1As shown, the present invention provides a thermal expansion valve, which includes a first diaphragm cover 10, a copper substrate 20 and a valve body 40. The first diaphragm cover 10 has a first surface, the valve body 40 has a second surface, the copper substrate 20 is overlapped with at least a portion of the first surface by a metallurgical structure, and the second surface is overlapped with the surface of the copper substrate 20 away from the first diaphragm cover 10 by a solder layer 30.

[0025] In one embodiment, the first diaphragm cover 10 is a stainless steel diaphragm cover, and the valve body 40 is a brass valve body 40.

[0026] In the thermal expansion valve provided by this utility model, the copper substrate 20 is fixed to the first diaphragm cover 10 by forming a metallurgical structure with at least a portion of the first surface of the first diaphragm cover 10. The surface of the copper substrate 20 away from the first diaphragm cover 10 and the second surface are welded and fixed by a solder layer 30. Thus, the valve body 40 is overlapped with at least a portion of the first surface of the first diaphragm cover 10 by the stacked copper substrate 20 and the solder layer 30, which can effectively avoid the risk of brittle phosphorus compounds being generated by the solder layer 30 contacting the first diaphragm cover 10, so that the thermal expansion valve has excellent tightness.

[0027] Meanwhile, the welding of the original first diaphragm cover 10 to the valve body 40 was changed to welding of the copper substrate 20 to the valve body 40. The material change not only eliminates the need for flux when using CuP-based solder, thus eliminating the need for subsequent flux cleaning process, reducing the production cost of the thermal expansion valve and simplifying the process; it also eliminates the need to use AgCuZn-based solder with high silver content, expanding the range of solder choices and allowing the use of lower-cost solders, such as CuP-based solder, further reducing the production cost of the thermal expansion valve.

[0028] In addition, due to the expanded range of solder selection, there are also more welding methods available. For example, lower-cost welding methods such as flame welding or high-frequency welding can be used. As a result, the thermal expansion valve provided by this utility model has the advantages of low production cost, simple connection process, high density and high welding qualification rate.

[0029] In one embodiment, the metallurgical structure is formed by a brazing process. It should be noted that the specific steps of the brazing process include bringing the copper substrate 20 into contact with at least a portion of the first surface of the first membrane cover 10 for a first welding operation. The process temperature for the first welding is between the solidus temperature and the liquidus temperature of the copper substrate 20, thereby allowing the copper substrate 20 to exist in a state of coexistence of solid and liquid phases (semi-molten), enabling the formation of a metallurgical structure between it and the first membrane cover 10. It should be noted that the solidus temperature of the copper substrate 20 refers to the temperature at which the copper substrate 20 begins to melt, and the liquidus temperature of the copper substrate 20 refers to the temperature at which the copper substrate 20 is completely melted.

[0030] In one embodiment, the solidus temperature of the copper substrate 20 is 880°C-1100°C; the liquidus temperature is 1030°C-1160°C. Within the above range, the higher the solidus temperature and the liquidus temperature, the higher the brazing temperature, and the easier it is to remove the oxide film on the stainless steel surface.

[0031] In one embodiment, the mass fraction of copper in the copper substrate 20 is greater than or equal to 95%, thereby better avoiding liquid phase aggregation in the copper substrate 20 during the brazing process. As a result, the thickness of the copper substrate 20 can be increased. In one embodiment, the thickness of the copper substrate 20 is 0.01mm-0.2mm, including but not limited to any value of 0.01mm, 0.05mm, 0.1mm, 0.15mm or 0.2mm or any range between two of them. The increase in thickness makes it easier to flip the copper substrate 20, making the connection process of the thermal expansion valve simpler.

[0032] In one embodiment, the copper substrate 20 is a copper-based binary alloy foil layer or a copper-based ternary alloy foil layer; for example, a CuSn alloy foil layer, a CuAg alloy foil layer, a CuSi alloy foil layer, a CuMn alloy foil layer, or a CuNi alloy foil layer. Preferably, the copper substrate 20 is selected from high-melting-point copper substrates such as CuAg alloy foil layers. It should be noted that when the copper substrate 20 is a CuSn alloy foil layer and the solder layer 30 contains Cu, for example, a CuP-based solder, a metallurgical reaction will occur between the copper substrate 20 and the solder during the welding process between the copper substrate 20 and the valve body 40. Therefore, an element diffusion layer is also present between the copper substrate 20 and the solder layer 30.

[0033] In one embodiment, the projected length of the copper substrate 20 on the first diaphragm cover 10 is a, and the projected length of the valve body 40 on the first diaphragm cover 10 is b. a and b satisfy the following condition: a > b. During the welding and fixing process, the edge of the solder layer 30 will generate a brazing angle 301. In order to better avoid the risk of brittle phosphorus compounds generated by the contact between the solder layer 30 and the first diaphragm cover 10, and to make the thermal expansion valve have excellent tightness, the wire diameter of the solder ring used during welding and fixing is φ. a, b, and φ satisfy the following condition: a ≥ b + φ.

[0034] In one embodiment, the solder layer 30 is a CuP-based solder layer, which includes, but is not limited to, a Cu91PAg solder layer.

[0035] In one embodiment, the thermal expansion valve further includes a copper tube overlapping at least a portion of the surface of the valve body 40.

[0036] The thermal expansion valve of this utility model can be prepared by the following method, which specifically includes the following steps:

[0037] S10, at least a portion of the copper substrate 20 is assembled onto the first surface of the first membrane cover 10 and a first welding is performed to form a metallurgical structure, wherein the process temperature during the first welding step is between the solidus temperature and the liquidus temperature of the copper substrate 20; and

[0038] S20, solder and valve body 40 are sequentially assembled on the surface of copper substrate 20 away from the first membrane cover 10, and a second welding is performed to obtain the thermal expansion valve.

[0039] In the preparation method of the thermal expansion valve provided by this utility model, the copper substrate 20 is first fixed to the first membrane cover 10 by the first welding; then the solder and valve body 40 are sequentially assembled on the surface of the copper substrate 20, and the second welding is performed to fix the surface of the copper substrate 20 away from the first membrane cover 10 to the second surface.

[0040] First, in step S10, the first welding adopts a brazing process, and the process temperature is between the solidus temperature and liquidus temperature of the copper substrate 20, so that the copper substrate 20 is in a state of coexistence of solid and liquid phases (semi-molten), and then the first film cover 10 is connected to the copper substrate 20 after cooling. When elements that increase the melting point are added to the copper substrate 20, the process temperature during the first welding can be increased to over 1000℃. At this time, the oxide film can be removed by relying on hydrogen or a vacuum environment, eliminating the use of flux, reducing production costs, and simplifying the process.

[0041] In order to better remove the oxide film on the surface of the first membrane cover 10, in one embodiment, the first welding is carried out in a vacuum or hydrogen-containing protective gas atmosphere.

[0042] Secondly, in step S20, since welding the valve body 40 to the first diaphragm cover 10 is replaced by welding the valve body 40 to the copper substrate 20, and since both the valve body 40 and the copper substrate 20 are made of copper, there is no need to use AgCuZn-based solder with high silver content, thus expanding the range of solder choices. Lower-cost solders, such as CuP-based solders, can be used. At the same time, the contact area between the copper substrate 20 and the first diaphragm cover 10 is larger than the contact area between the solder and the valve body 40, which can effectively avoid the risk of brittle phosphorus compounds being generated when the solder comes into contact with the first diaphragm cover 10, which is made of stainless steel. This gives the thermal expansion valve excellent tightness. In addition, due to the expansion of the range of solder choices, there are also more welding methods available. For example, lower-cost welding methods such as flame welding or high-frequency welding can be used, further reducing the production cost of the thermal expansion valve.

[0043] In one embodiment, the welding temperature is 780°C-820°C, including but not limited to 780°C, 790°C, 800°C, 810°C or 820°C.

[0044] A second aspect of this invention provides a refrigeration system, including the thermostatic expansion valve described above.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A thermostatic expansion valve, characterized in that, The device includes a first membrane cover, a copper substrate, and a valve body. The first membrane cover has a first surface, the valve body has a second surface, the copper substrate is overlapped with at least a portion of the first surface by a metallurgical structure, and the second surface is overlapped with the surface of the copper substrate opposite to the first membrane cover by a solder layer.

2. The thermostatic expansion valve according to claim 1, characterized in that, The projected length of the copper substrate on the first diaphragm cover is a, and the projected length of the valve body on the first diaphragm cover is b. a and b satisfy the following condition: a > b.

3. The thermostatic expansion valve according to claim 1, characterized in that, The copper substrate is a copper-based binary alloy foil layer or a copper-based ternary alloy foil layer.

4. The thermostatic expansion valve according to claim 3, characterized in that, The copper substrate is a CuSn alloy foil layer, a CuAg alloy foil layer, a CuSi alloy foil layer, a CuMn alloy foil layer, or a CuNi alloy foil layer.

5. The thermostatic expansion valve according to any one of claims 1-4, characterized in that, The thickness of the copper substrate is 0.01mm-0.2mm.

6. The thermostatic expansion valve according to any one of claims 1-4, characterized in that, The copper substrate includes a folded portion.

7. The thermostatic expansion valve according to any one of claims 1-4, characterized in that, An element diffusion layer exists between the copper substrate and the solder layer.

8. The thermostatic expansion valve according to any one of claims 1-4, characterized in that, The solder layer is a CuP-based solder layer.

9. The thermostatic expansion valve according to any one of claims 1-4, characterized in that, The first membrane cover is a stainless steel membrane cover; and / or, the thermal expansion valve further includes a copper tube overlapping at least a portion of the surface of the valve body.

10. A refrigeration system, characterized in that, Includes the thermal expansion valve as described in any one of claims 1-9.

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