This application claims priority to European Patent Application No. 21181071.8 filed Jun. 23, 2021, the entire disclosure of which is incorporated herein by reference.
The current application relates to improved fitting of an electrical terminal for a compressor, in particular a scroll compressor, wherein such compressor could be used, for example, in refrigeration systems. The fitting of the electrical terminal provides for improved durability and welding characteristics.
A compressor is an apparatus, which reduces the volume of a fluid by increasing the pressure of the fluid. In most common applications, the fluid is a gas.
The compressors are used, for example, in refrigeration systems. In a common refrigeration system, a refrigerant is circulated through a refrigeration cycle. Upon circulation, the refrigerant undergoes changes in thermodynamic properties in different parts of the refrigeration system and transports heat from one part of the refrigeration system to another part of the refrigeration system. The refrigerant is a fluid, i.e. a liquid or a vapour or gas. Examples of refrigerants may be artificial refrigerants like fluorocarbons. However, in recent applications, the use of carbon dioxide, CO2, which is a non-artificial refrigerant, has become more and more important, because it is non-hazardous to the environment.
Usually, a compressor forms a hermetically sealed volume. In order to provide signals to a component inside the hermetically sealed volume, the compressor comprises at least one electrical terminal. A component inside the hermetically sealed volume may for example be a motor, which operates the compressor, a sensor within the compressor or a controller within the compressor. The signals, which can be provided to a component inside the hermetically sealed volume may be any of a power supply, a data signal or control signal connection or any combination thereof, wherein the data or control signals may for example be used for adjusting the operation of a motor of the compressor. The electrical terminal is used for establishing a connection of at least one component within the hermetically sealed volume of the compressor and at least one component outside the compressor. For example, the electrical terminal may be used to establish a connection with an electricity network and/or a controller. As the person skilled in the art will understand, the electrical connection may be used to provide signals to the compressor or its components (e.g. the motor), but the electrical connection may also be used to provide signals from the compressor or its components (e.g. the motor)—for example, the compressor may provide a status report via the electrical connection. Such a status report may for example include information about the operation of the motor (e.g. the operating speed in rounds per minute), temperature readings of suction temperature or discharge temperature, or any other suitable information.
A typical compressor comprises a case and at least one opening for receiving the electrical terminal. The electrical terminal is placed in the opening and welded to the case. Usually, the case of a compressor is curved, for example in a way that at least a portion of the case is formed in the shape of a hollow cylinder, which is capable of withstanding high pressures.
However, in order to allow a welding of the electrical terminal to the case, the case usually comprises a flat surface portion and the opening for receiving the electrical terminal is located in the flat surface area. The flat surface area provides a portion of the surface of the case, which has a flat shape and a reduced local stiffness. This allows for easy assembly of the electrical terminal in the opening, a tight fit of the electrical terminal in the opening and enables welding the electrical terminal to the edge of the opening. Such a flat area may, for example, be created by coining a portion of the case. A compressor with a coined case and an electrical terminal located in the flat surface area according to the state of the art is depicted in
However, flattening an area of the case of the compressor has major drawbacks. For example, the flattening may weaken the case substantially, so that the case is prone to bursts. This issue arises particularly in scroll compressors used for CO2 refrigerants, since these scroll compressors operate at a higher pressure than compressors for most common artificial refrigerants. Besides operation at high pressure, the case may also burst because of fatigue.
Hence, there is a need in the art for improving the durability of a compressor case. For improved durability, it is necessary to avoid any local weakening of the case of the compressor as would be caused by coining the case.
The above-mentioned need is fulfilled by the compressor case and electrical terminal according to the current invention.
According to the current invention, a compressor is provided, which comprises a case and at least one electrical terminal. The case has at least one curved portion and at least one opening, wherein the opening is located in the at least one curved portion and wherein the electrical terminal is arranged within the opening and is fixed to the case. The curved portion of the case may be convex with respect to the outside of the case. In a preferred embodiment, at least a portion of the case may form a hollow cylinder and the curved portion is part of the portion that forms the hollow cylinder. For the purpose of this application, a compressor configuration in which at least a portion of the case forms a hollow cylinder is referred to as “cylindrical case”. The hollow cylinder may comprise a top, a bottom and a lateral surface. The top and/or the bottom of the case may be curved, e.g. in form of a hemisphere or may be flat. In any of these preferred embodiments, the curved portion may be formed by the curvature of the hollow cylinder.
Preferably, the case comprises one opening for each electrical terminal. In case that the case comprises more than one opening for receiving more than one electrical terminal, the case may comprise more than one curved portion. In an example, a curved portion of the case may comprise more than one opening, whereas in another example, the case may comprise a curved portion for each opening. The one or more curved portions may have the same curvature or may have different curvatures. In the above-mentioned preferred embodiment, in which a portion of the case forms a hollow cylinder, the cylindrical shape of the hollow cylinder may form a single curved portion and each opening in the case is located in said curved portion.
According to the current invention, the at least one opening is an elliptical opening, or in other words, the opening has the form of an ellipse. The ellipse is characterized by two geometrical parameters, which are often referred to as minor axis and major axis. Thereby, the minor axis refers to the distance between the two opposing points of the ellipse, which have the shortest distance, sometimes referred to as narrowest part of the ellipse. The major axis refers to the distance between the two opposing points of the ellipse, which have the longest distance. In this regard, the term “opposing points” specifies that a connection line between the two points, which are referred to as opposing each other, goes through the center of the ellipse. The minor axis and the major axis are perpendicular to one another. Further, the semi-axis of the minor axis, i.e. half the extend of the minor axis, is known as semi-minor axis and the semi-axis of the major axis, i.e. half the extend of the major axis, is known as semi-major axis.
Preferably, the major axis of the ellipse is aligned with the curvature of the curved portion, as is for example depicted in
The shape of the elliptical opening may be specified differently for different embodiments. For example, in some embodiments in which at least a portion of the case forms a hollow cylinder, the elliptical opening may have an elliptical shape in the lateral surface of the hollow cylinder. This means that the opening is elliptical in the lateral surface of the case. For example, if the three-dimensional lateral surface of the case is unwound into a two-dimensional plane, the opening may be represented by an ellipse in said two-dimensional plane.
In some other embodiments, a projection of the opening into a two-dimensional projection plane may have an elliptical shape. In other words, the projection of the opening along a normal axis through the center of the elliptical opening into the two-dimensional projection plane may be elliptical.
The elliptical opening in a curved portion of the case allows to provide an improved fit between the electrical terminal and the case. The elliptical opening comprises an increase in the size of the opening in the curved direction of the case compared to a circular opening as will be described later with respect to
During assembly of the compressor, the electrical terminal is placed in the elliptical opening and fixed to the case. This fixing may be realized by fixing a portion of the electrical terminal to a boundary that forms the elliptical opening in the case. The fixing may be performed by welding a portion of the electrical terminal to the boundary. At the locations at which the portion of the electrical terminal is fixed to the case, a connection between the electrical terminal and the case is established. Said connection may be a sealed connection—e.g. sealed by welding. Forming a sealed connection has the benefit that the compressor case can hold a hermetically sealed volume.
Because of the elliptical opening, the welding contact of the fitting the protrusion of the electrical terminal and the boundary of the elliptical opening of the case is longer compared to a fitting of a state of the art terminal in a circular opening, as will be described below in more detail, e.g. with respect to
In the following, further preferred embodiments of the current invention are described.
The electrical terminal may comprise a body, at least one connection pin, an insulator, and a protrusion. Preferably, the body of the electrical terminal has a circular cross-section. This way, the body of the electrical terminal may be a cylindrical body, which may also form a disk from which the protrusion extends and to which the at least one connection pin and the insulator may be attached. This allows for the possibility to place the electrical terminal within the opening in any rotational orientation with respect to a normal axis of the cross-section of the circular terminal body. The protrusion may extend from the body in an angle with respect to the cross-section of the terminal body. Preferably, the protrusion extends from the body in an angle of approximately 45 degrees. Other preferred angles may be 30, 60, or 75 degrees. Any of these configurations improve the assembly of the electrical terminal in the opening and the welding of the electrical terminal to the case, since the electrical terminal can be placed in the opening in any rotational orientation and the protrusion of the electrical terminal can be used to weld the electrical terminal to the case of the compressor.
The at least one connection pin can be used to connect the electrical terminal to an external network, e.g. a power network, a network for transmitting and/or receiving signal, or a combination of both. The at least one connector pin may extend through the body of the electrical terminal and thereby may provide for a connection of any component within the compressor to the external network.
The at least one connection pin may be isolated from the body via the insulator. For example, the insulator may surround the portion of the at least one connection pin, which may extend through the body. Since in most cases the body is made of metal, the insulator may enable proper operation of the at least one connection pin.
The protrusion may be used for fixing at least a portion of the electrical terminal to the case. The protrusion may extend from the body of the electrical terminal. Therefore, during assembly of the electrical terminal to the case, the electrical terminal may be placed in the opening in the case from the inside, so that the body of the electrical terminal is located within the opening but the protrusion, which has a wider spatial extend, prevents that the electrical terminal can pass through the opening entirely. Then, the protrusion may contact the case of the compressor, for example at an edge of the opening, and can be welded to the case. Compared to an electrical terminal according to the state of the art, the protrusion is increased in size, meaning that the radial extend of the protrusion is increased. The elliptical opening is fabricated into the case and a welding joint is formed between the case and the protrusion of the electrical terminal. The size of the electrical terminal, in case of a cylindrical body its outer diameter, could be independent of the size of the elliptical opening. In general, the minor axis of the elliptical opening may be slightly larger than a first diameter of the body of the terminal. Therefore, the terminal can easily be fitted into the opening. It is preferred that there is a small gap between the body and the case, so that the welding may only be made between the edge of the elliptical opening and the protrusion of the electrical terminal. Since the body may comprise insulating material, heat applied to the body should preferably be avoided, because otherwise the insulating material may be damaged.
In some embodiments, the protrusion may form a truncated cone. The truncated cone may be hollow. The truncated cone may additionally be symmetrical with respect to the circular cross-section of the body of the electrical terminal. This improves the fitting between the case and the electrical terminal, when the electrical terminal is placed in the elliptical opening.
In some embodiments, the body may have a first outer diameter. Since the protrusion extends from the body at an angle, the protrusion may have a variable outer diameter. Accordingly, the protrusion may have a maximum outer diameter. The maximum outer diameter of the protrusion may be greater than the first outer diameter, for example the maximum outer diameter may be at least 1.4 times the first outer diameter. Such a ratio between the first outer diameter and the maximum outer diameter may guarantee that the protrusion is large enough to cover the entire elliptical opening and also provide enough contact between the protrusion and the boundary of the elliptical opening for establishing a sealed welding contact. When the electrical terminal is placed in the elliptical opening having a minor axis and a major axis, the first outer diameter of the body of the electrical terminal may have a size of the minor axis plus two times a first gap size. Preferably, the gap size may be 0.1 mm.
In some embodiments, the body of the electrical terminal may comprise a front side directed to the outside of the case, when assembled, and a back side directed to the inside of the case, which form opposing sides of the body. In case that the electrical terminal has a body with a circular cross-section or is formed as a hollow cylinder, the front side and the back side may be the top and the bottom of the body. The protrusion may extend from the back side of the body and the body may comprise a recess located at the back side of the body of the electrical terminal. The recess may reduce the contact area between the body and the protrusion or—in case that the body and the protrusion are formed integrally—the recess may reduce the transition area between the body and the protrusion. Thereby, the recess may reduce the heat transfer between the protrusion and the body. For example, if the protrusion of the electrical terminal is welded to the case of the compressor, a large amount of heat is generated in the protrusion. This heat may dissipate into the body of the electrical terminal and may harm the insulator, which isolates the at least one connector pin. The recess may reduce or slow down heat dissipation from the protrusion into the body.
Further, in any of the aforementioned embodiments, the body of the electrical terminal and the protrusion may be formed integrally. This has the advantage that the joining provides a true hermetic sealing and the manufacturing process is simple.
The above-mentioned need is also fulfilled by an electrical terminal according to the current invention. The electrical terminal is configured for being fitted into an opening of a case of the compressor, wherein the opening is an elliptical opening.
Said electrical terminal may be similar to any of the electrical terminals, which have been described above for the system comprising the case with at least one elliptical opening and at least one electrical terminal.
The following description and the annexed drawings set forth in detail certain illustrative aspects of the apparatus and the method described above. These aspects are indicative, however, of but a few of the various ways in which the principles of various embodiments can be employed and the described embodiments are intended to include all such aspects and their equivalent. In particular it needs to be highlighted that—although the following drawings only show embodiment examples of scroll compressors—the invention may be applied to any type of compressor.
In the drawings, like reference characters generally refer to the same parts throughout the different drawings. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.
In the following description, various embodiments of the invention are described with reference to the following drawings, in which:
The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs.
Further, the compressor 100 comprises a motor no, which actuates the orbiting scroll plate 106, and a lubricant reservoir 112 used for providing lubricant to the motor no and the scroll plates 104, 106.
The compressor boo comprises a case 114. In order to provide a connection to an external network, the case 114 of the compressor 100 comprises at least one opening in which an electrical terminal 116 is placed. The electrical terminal 116 comprises connection pins for establishing a connection with an external network.
An electrical terminal according to the state of the art is depicted in
The electrical terminal 200 comprises two portions, namely a body 202 and a protrusion 204. The body 202 forms a hollow cylinder with a first outer diameter d1,1. The protrusion 204 forms a hollow truncated cone as is depicted in
At least one connector pin 208 is attached to the body. In order to insulate the connector pins from the body 202 of the electrical terminal 200, the at least one connector pin 208 is surrounded by an insulator 206, so that the insulator contacts the body 202 directly, while the at least one connector pin 208 does not directly contact the body 202. The insulator 206 may be made from a plastic material, a glass material, or a combination of both. The insulator 206 may have the form of a plate covering the front side of the electrical terminal 200 as is depicted by ease of the circle with the dashed circumference in
In the embodiment example depicted in
The electrical terminal 400 comprises two portions, namely a protrusion 404 and a body 402. The body 402 may comprise a cylindric body with a first outer diameter d1,2. The protrusion 404 forms a hollow truncated cone as is depicted in
Compared to the protrusion 204 of the electrical terminal 200 according to the state of the art depicted in
The protrusion 404 and the cylindrical body 402 may be formed integrally. Alternatively, the protrusion may be a separate element and may be attached to the body. In this case, an insulating layer may be added between the body and the protrusion. Such an insulating layer may reduce heat transfer from the protrusion to the body during welding. Further, the protrusion and/or the body may be made of metal.
At least one connector pin 408 and an insulator 406 are attached to the body 402. The at least one connector pin 408 and the insulator 406 with outer diameter d3,2 are similar to the at least one connector pin 208 and the insulator 206 of the electrical terminal 200 depicted in
In the embodiment example depicted in
Hence, there is a gap x formed between the case and the body 402 of the electrical terminal 400. In welding area 510a, the gap x is smaller than in welding area 510b. If the electrical terminal 400 is formed with a cylindrical body 402 as depicted in
Accordingly, the gap size is minimal for welding areas 510a along the minor axis of the elliptical opening, i.e. xmin=x(γ=0°)=x(γ=180°)=b−r, whereas the gap size is maximal for welding areas 510b along the major axis of the elliptical opening, i.e. xmax=x(γ=90°)=x(γ=270°)=a−r.
However, electrical terminal 600 comprises a recess 610 at the backside of the body 602. In this regard, backside of the body 602 means that this side faces the inner portion of the case when the electrical terminal is assembled in the opening of the case. The recess 610 may be circular and may have a diameter d4,3, which is smaller than the diameter d1,3 of the body 602, but greater than the diameter d3,3 of the insulator. Although it is depicted in this way in
What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims.
Number | Date | Country | Kind |
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21181071.8 | Jun 2021 | EP | regional |