Patent Application
20230238734
The present invention relates to a hermetic electric compressor with an electric motor. The compressor comprises a hermetic terminal as part of the housing, and comprises at least two terminal pins to electrically connect at least one winding of the electric motor to an external power source. The power source is typically a grid connection but could also be a battery connection or a connection to other sources of energy.
The hermetic terminal of such compressors typically comprises a terminal holder forming part of the housing, typically welded into the wall of the housing. The hermetic terminal may comprise at least two terminal pins made of an electrically conductive material. These terminal pins extend through the terminal holder. An insulative element is arrange to insulate the terminal pin from the terminal holder.
Hermetic electric compressors comprise an electric motor accommodated in a sealed housing. Such compressors are used e.g. for household refrigeration, light commercial refrigeration, and heating purpose. The sealed housing contains a refrigerant which is circulated between a condenser and an evaporator. By phase shifts between liquid and vapour phases, thermal exchange can provide efficient heating and cooling. Examples of refrigerants include R134a, R407C, R744 (CO2), and R290.
The hermetic terminal includes terminal pins, which are formed from a conductive material, e.g. different kinds of alloys such as steel, and a terminal holder, which holds the terminal pin. The terminal holder is typically made of alloys such as steel. An insulative element, i.e. a material, such as a ceramic, glass, or epoxy is arranged between the terminal pin and the terminal holder, and the terminal holder is typically welded into an opening in the sealed housing of the compressor and thereby preserves the sealed structure of the compressor.
Often, the electric motor comprises a main winding and an auxiliary winding, and to power the windings, the hermetic terminal comprises three terminal pins, one for connecting a common potential, i.e. the zero or phase, and the two other terminal pins for connecting to each of the main winding and auxiliary winding. The electric motor could also be a DC motor, or a permanent magnet AC or DC motor etc.
Embodiments of the disclosure provide an electric compressor further comprising a non-conductive sealing element defining an enclosed space in the cavity.
During operation liquids constituted by lubricant and refrigerant in the housing contaminates the insulative sealing element. The liquids typically contain metallic particles arising from wear of moving metal parts in the compression assembly and the electric motor. When the insulative sealing elements are contaminated with such contaminated liquids, a leak current may develop between the terminal pin and the terminal holder, i.e. across the insulative sealing elements.
The sealing element may particularly form a closure for the cavity and thereby protect the insulative sealing elements against contamination by forming an enclosed space in the cavity.
The terminal holder may define an edge extending about the cavity and the sealing element may be configured to seal against the edge to thereby define the enclosed space in the cavity.
The sealing element may comprise a plug structure configured to electrically engage the terminal pins and connect them to the electric motor.
The plug structure may be configured to maintain the sealing element against the edge by the engagement between the terminal pins and plug structure.
The electric compressor may define an operational orientation. This orientation may particularly be required to collect liquids in a bottom part etc. The plug structure may define a cable direction in which cables extend away from the hermetic terminal, the cable direction being downwards relative to gravity when the electric compressor is in the operational orientation.
The sealing element may form a base and an annular wall extending upwards from the base and configured to enter into the cavity. The annular wall may particularly be in sealing contact with an inner surface of the cavity and thereby increase the sealed conditions of the cavity and it may increase the fixation of the sealing element onto the terminal holder. The annular wall and the base may be formed in one piece, e.g. in a resilient or elastically deformable material, e.g. a rubber material.
The sealing element may comprise at least one annular ridge extending upwards from the base, e.g. extending about the annular wall outside the cavity. The annular ridge may form an efficient way of preventing liquids on the base from reaching the annular wall. The ridge or ridges may particularly extend in one or more rings about the annular wall, and they may have a triangular shape in a cross-section transverse to the ring shape.
In one embodiment, at least one of: the cavity formed by the terminal holder, the annular wall, and the annular ridges, may be circular. Particularly, the cavity and the annular wall may have matching circular shape and size such that the annular wall can be received snugly in the cavity and maintained therein by friction between an outer surface of the annular wall and an inner wall of the cavity formed by the terminal holder.
At least one annular ridge may extend in parallel with the annular wall. This embodiment could be achieved by a circular annular wall coaxially aligned with one or more circular ridges.
At least one of the annular wall or annular ridge may comprise at least one indentation defining an opening across the annular wall or annular ridge. The indentation may form a score from an upper edge of the wall or ridge and all the way to the base. The indentation may allow liquids trapped in the cavity or trapped between the annular wall and one of the ridges to be drained via the indentation.
The electric compressor may, as mentioned previously, define an operational orientation, e.g. based on the location where liquids are collected for an oil pump inlet etc. At least on indentation may be located in a downwards portion of the annular ridge or annular wall relative to gravity when the electric compressor is in the operational orientation.
In one embodiment, the sealing element comprises at least two indentations defining an opening across one of the annular wall or annular ridge.
At least two indentations may be symmetrical placed with respect to a vertical plane when the electric compressor is in the operational orientation.
The base may form a plane surface which is transverse to or perpendicular to the terminal pins. The plane surface may particularly be an inner surface facing inwards towards the cavity which is closed by the sealing element.
The electric motor may particularly have a main winding and an auxiliary winding used during start of the motor. For this purpose, the electric compressor may particularly comprise three terminal pins extending through the terminal holder and connected to the electric motor such that one pin connect to a corresponding winding and the third pin forms zero for both windings.
In a second aspect, the disclosure provides a method of sealing a cavity of a hermetic terminal for an electric compressor, the method comprising providing a sealing element configured to define an enclosed space in the cavity, the sealing element being provided with an integrated plug structure, and the plug structure is utilized for keeping the sealing element against an edge of the terminal holder to thereby define the enclosed space in the cavity.
The disclosure will now be described in further detail with reference to the accompanying drawings in which:
The following description refers to an embodiment of the disclosure.
The cavity formed by the terminal holder is terminated upwardly by the circumferential edge 14 of the sidewall 15. The sidewall is welded into the compressor housing and thereby forms one single unit with the compressor housing.
In addition to the sealing against ingress of liquids into the enclosed space, the sealing element has the feature of connecting the motor electrically. For that purpose, the sealing element comprises a plug structure 17, 18 forming one connection plug opening 17 for each terminal pin in the hermetic terminal. The plug structure is configured to electrically engage the terminal pins and connect them individually to the electric motor via cables (not shown). The cables, when mounted, extend through the openings 18 defining a cable direction indicated by the arrow.
Each of the plug openings 17 may include resilient spring means forming a firm grip against the surface of the terminal pins and the plug structure thereby further functions as a retaining means for retaining the position of the sealing element 16 against the edge 14 of the terminal holder 5. The resilient spring means is of a kind generally known e.g. from sockets, e.g. from power sockets.
The sealing element 16 forms a base 19 and an annular wall 20 extending upwards from the base and configured to enter into the cavity. The annular wall and the terminal holder have matching sizes and shapes such that the annular wall fits tightly into the cavity, e.g. such that the annular wall 20 is in contact with the sidewall 15. In this way, the annular wall supports the fixation of the sealing element onto the hermetic terminal and supports the function of preventing ingress of liquids into the cavity.
In the disclosed embodiment, the sealing element further comprises a plurality of annular ridges 21 extending upwards from the base. The ridges are lower than the annular wall 20 but they extend in parallel with the annular wall, circumferentially around the annular wall. In the disclosed embodiment, both the ridges and the wall are circular. The annular ridges extend outside the cavity when the sealing element is attached to the terminal holder.
Both the annular wall and the annular ridges comprise indentations 22. These indentations provide a discontinuity of the wall and ridges and thereby define openings across the wall or and ridges.
The electric compressor may define an operational orientation. This orientation is typically dictated by gravity acting on liquids in the housing and ensures that lubrication oil reaches the oil pump etc.
In
In all illustrations, the hermetic terminal comprises three terminal pins. This corresponds to a zero pin and one phase for each winding of a motor with a main winding and an auxiliary winding. However, other numbers of terminal pins and other ways of connecting the terminal pins to the motor may be considered within this disclosure, e.g. two terminal pins for connecting phase and zero to a motor requiring only one phase connector, e.g. a motor having only one winding.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20180802.9 | Jun 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/066671 | 6/18/2021 | WO |
