EP3090174A1

EP3090174A1 - Reciprocating compressor with reduced size and improved shape for use in a refrigeration appliance

Info

Publication number: EP3090174A1
Application number: EP13802009.4A
Authority: EP
Inventors: Erkan Ozkan; Umit Gencay BASCI; Alper YESILCUBUK
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2013-11-29
Filing date: 2013-11-29
Publication date: 2016-11-09
Also published as: WO2015078532A1

Abstract

The present invention relates to a compressor (1) for use in a refrigeration appliance, in particular a domestic refrigerator (2). The compressor (1) comprises a casing (3) which includes a cylinder block (4) which has a chamber (5) for compressing a refrigerant, a piston mechanism for compressing the refrigerant in the chamber (5) and an electrical motor (6) for driving the piston mechanism. In the compressor (1) of the present invention, the motor (6) has a stator (7) and a rotor (8) which are separated by a gap (9) in an axial direction (Ax) that is perpendicular to a rotation plane of the rotor (8). The rotor (8) is rotatably secured to the casing (3) via a support mechanism which is separately provided from the cylinder block (4) and the piston mechanism. The piston mechanism is coupled to the rotor (8) via a pivot (10) which is eccentrically mounted to the rotor (8).

Description

RECIPROCATING COMPRESSOR WITH REDUCED SIZE AND IMPROVED SHAPE FOR USE IN A REFRIGERATION APPLIANCE

The present invention relates to a reciprocating hermetic compressor for use in a refrigeration appliance, in particular a domestic refrigerator.
A domestic refrigerator is typically provided with a reciprocating compressor for circulating a cooling refrigerant of the refrigeration circuit. The conventional reciprocating compressor is usually arranged in a lower cabinet of the domestic refrigerator. The cabinet should at least possess a size and shape which suits the compressor. Therefore, a corresponding volume of the domestic refrigerator must be reserved for the cabinet. Consequently, the utilizable volume for the refrigeration compartments generally reduces. One way to compensate for the reduction in the utilizable volume is to provide a domestic refrigerator with larger dimensions. However, this incurs additional manufacturing costs. Another way to gain more utilizable space is to reduce the compressor size. However, design limitations and operational constraints generally prevent attaining a significant reduction in the size of a compressor.
Fig. 1 shows a conventional reciprocating compressor (1´). The conventional reciprocating compressor (1´) has a casing (3´) which is typically made of an upper part (3a´) and a lower part (3b). The casing (3´) encloses a cylinder block (4´) which has a chamber (5´) for compressing a refrigerant, a piston mechanism for compressing the refrigerant in the chamber (5´) and an electrical motor (6´) for driving the piston mechanism. In the conventional reciprocating compressor (1´), the piston mechanism comprises a piston head (21´) arranged to reciprocate within the chamber (5´), a piston rod (22´) and a crank shaft which are serially coupled to each other. The crankshaft is rotatably supported solely by the cylinder block (4´). In the conventional reciprocating compressor (1´), the electrical motor (6´) comprises a stator (7´) and a rotor (8´) which are typically configured as an asynchronous motor or a brushless direct current motor. The rotor (8´) is fixed to the crank shaft of the piston mechanism. In the conventional reciprocating compressor (1´), the cylinder block (4´) and the stator (7´) are firmly fixed to a pillar-like support which is further fixed to a lower part (3b´) of the casing (3´) via a damping mechanism.
A problem with the reduction of the size of the constituent parts of the compressor is that such modifications generally result in a significant amount of reduction in the refrigeration capacity.
An objective of the present invention is to provide a reciprocating compressor which overcomes the aforementioned problems of the prior art and which increases the utilizable volume of a refrigerator without compromising its refrigeration capacity.
This objective has been achieved by the compressor according to the present invention as defined in claim 1, and the refrigeration appliance according to the present invention as defined in claim 15. Further achievements have been attained by the subject-matters respectively defined in the dependent claims.
In the compressor of the present invention, the motor is an axial flux motor which has a stator and a rotor. The stator and the rotor are separated by a gap in an axial direction which is perpendicular to a rotation plane of the rotor. The rotor is rotatably secured to the casing via a support mechanism which is separately provided from the piston mechanism and the cylinder block. The piston mechanism is coupled to the rotor via a pivot that is eccentrically mounted to the rotor.
By virtue of the support mechanism of the present invention, the conventional fixing of the rotor to the crank shaft becomes superfluous. By virtue of the pivot of the present invention, the conventional use of the crank shaft becomes also superfluous. Therefore, the crank shaft can be completely dispensed with. Moreover, in the absence of the crank shaft, the conventional bearing provided in the cylinder block which supports the crank shaft becomes also superfluous. Therefore, the conventional bearing in the cylinder can also be dispensed with. Thus, the height of the cylinder block can be substantially reduced. By the present invention a substantial reduction in the height of the compressor has been attained. The axial flux motor generally produces a magnetic flux in the axial direction. The axial flux motor has generally a reduced height in comparison to a conventionally used motor. In the present invention, the required torque for the piston mechanism has been attained by securing a sufficiently large horizontal area for the rotor and the stator. Thereby, the size of a conventional compressor has been reduced without compromising its refrigeration capacity.
In an embodiment, the support mechanism has a bearing which rotatably secures the rotor. The bearing is embedded in a support which is directly fixed to the casing.
In another embodiment, the rotor, the bearing and the support each has an annular shape which together define a passage for conveying lubricant from a bottom of the casing to a vicinity of the moving parts. In a version of this embodiment, an oil conduit is rotatably arranged in the lubricant passage. In another version of this embodiment, the conduit is funnel shaped. A small open end of the conduit is immersed in the oil that is accumulated in a bottom of the casing whereas the large open end opens towards the piston mechanism.
In another embodiment, a radial position of the pivot is adjustable through an adjusting mechanism which is built into the rotor. Thereby, the compressor can be adapted to different refrigeration appliances to attain a reduced or increased refrigeration capacity.
In another embodiment, the pivot is a pin which is centered at position outside an annular opening of the rotor.
In another embodiment, the rotor has a mounting disc which has a plurality of permanent magnets which are fixed on its lower surface along an annular array around the axial direction so as to pick up an axial magnetic flux generated by the stator. The stator is arranged below the rotor. The pivot is eccentrically arranged on an upper surface of mounting disc. The cylinder block is arranged above the rotor. Thereby a very compact arrangement is attained. In a version of this embodiment, a plurality of winding coils are mounted onto pedestals which are arranged on a bottom of the casing along an annular array around the axial direction so as to oppose the plurality of magnets.
In another embodiment, the casing is configured by an upper part and a lower part. The cylinder block is fixed to the upper part. The stator is fixed to the lower part of the casing. The support mechanism is also mounted to the lower part of the casing. In a version of this embodiment, a suction silencer is arranged in an upper part of the casing for drawing refrigerant from a refrigeration circuit through an intake conduit. In another version of the embodiment, the intake conduit is arranged on an upper wall of the upper part of the casing. In another version of the embodiment, a cylinder head of the cylinder block is arranged on a lateral wall of the upper part of the casing.
By virtue of the axial flux motor and the coupling between the piston mechanism and the rotor, a size of the compressor has been reduced and also a sufficient refrigeration capacity has been secured despite of the reduced size. The compressor of the present invention has a relatively small height and is generally flat shape. Thereby, the utilizable volume for the refrigeration compartments has been effectively increased. The compressor of the present invention is compact and easy to assemble.
Additional advantages of the compressor according to the present will become apparent with the detailed description of the embodiments with reference to the accompanying drawings in which:
Figure 1 – is a schematic cross sectional view of a conventional reciprocating compressor;
Figure 2 – is a schematic cross sectional view of the reciprocating compressor according to an embodiment of the present invention;
Figure 3 – is a schematic perspective view of the reciprocating compressor according to an embodiment of the present invention;
Figure 4 – is a schematic rear view of a domestic refrigerator which comprises the reciprocating compressor according to an embodiment of the present invention.
The reference signs appearing on the drawings relate to the following technical features.

Compressor
Domestic refrigerator
Casing

3a. Upper part
3b. Lower part
4. Cylinder block
5. Chamber
6. Electrical motor
7. Stator
8. Rotor
9. Gap
10. Pivot
11. Annular bearing
12. Supporting member
13. Inner flange
14. Outer flange
15. Annular passage
16. Oil conduit
16a. Large open end
16b. Small open end
17. Annular opening
18. Mounting disc
19. Lower surface
20. Permanent magnet
21. Piston head
22. Piston rod
23. Upper surface
24. Winding coil
25. Pedestal
26. Suction silencer
27. Intake conduit
28. Intake port
29. Upper wall
30. Cylinder head
31. Exhaust port
32. Exhaust conduit
33. Lateral wall
34. Condenser
35. Expansion valve
36. Cabinet
37. Mounting lug
38. Service conduit
39. Electrical connector
The reciprocating hermetic compressor (1) is suitable for use in a refrigeration appliance, in particular a domestic refrigerator (2) (Figs. 2 to 4). The compressor (1) comprises a casing (3) which includes a cylinder block (4) which has a chamber (5) for compressing a refrigerant, a piston mechanism for compressing the refrigerant in the chamber (5) and an electrical motor (6) for driving the piston mechanism (Fig. 2).
In the compressor (1) according to the present invention, the motor (6) has a stator (7) and a rotor (8) which are separated by a gap (9) in an axial direction (Ax) that is perpendicular to a rotation plane of the rotor (8) (Fig. 2). In the present invention the compressor (1) has no conventional crank shaft, thus, being shaftless. Instead, the rotor (8) is rotatably secured to the casing (3) via a support mechanism which is separately provided from the piston mechanism and the cylinder block (4) (Fig. 2). The piston mechanism is coupled to the rotor (8) via a pivot (10) that is eccentrically mounted to the rotor (8) (Fig. 2).
In an embodiment, the support mechanism comprises an annular bearing (11) which is configured to rotatably support the rotor (8) (Fig. 2). The support mechanism further comprises a supporting member (12) which is configured to support the annular bearing (11) (Fig. 2). In this embodiment, the supporting member (12) is directly fixed to a casing (3) (Fig. 2).
In another embodiment, the rotor (8) is annular shaped and has an inner flange (13) that is fixed to an inner ring (not shown) of the annular bearing (11) (Fig. 2). In this embodiment, the supporting member (12) is also annular shaped and has an outer flange (14) that is fixed to an outer ring (not shown) of the annular bearing (11) (Fig. 2). The annular rotor (8), the annular bearing (11) and the annular supporting member (12) define an annular passage (15) for the oil which is accumulated on a bottom of the casing (3).
In another embodiment, the compressor (1) has an oil conduit (16) for conveying oil from a bottom of the casing (3) to a vicinity of the piston mechanism (Fig. 2). The oil conduit (16) is fixed to an annular opening (17) of the rotor (8) (Fig. 2). With the rotation of the rotor (8), the oil is centrifuged upwards.
In another embodiment, the oil conduit (16) is funnel shaped and has two open ends (16a; 16b) which are in fluid communication (Fig. 2). The smaller open end (16a) is immersed in the oil which is accumulated in a bottom of the casing (3) whereas the large open end faces the piston mechanism (Fig. 2).
In another embodiment, the rotor (8) comprises a position adjusting mechanism (not shown) which is configured to adjust a position of the pivot (10) in a radial direction i.e., perpendicular to the axial direction (Ax) (Fig. 2). Thereby, the refrigeration capacity of the compressor (1) can be adjusted to different refrigeration appliances.
In another embodiment, the pivot (10) is a cylindrical shaped pin which is formed on the rotor (8) (Fig. 2). The pin extends in an axial direction (Ax) (Fig. 2). The pin is located, i.e., centered at position which is outside an annular opening of the rotor (8) (Fig. 2).
In another embodiment, the rotor (8) comprises a mounting disc (18) which is rotatably arranged around the axial direction (Ax) and which has a lower surface (19) parallel to the rotation plane and a plurality of permanent magnets (20) which are fixed onto the lower surface (19) along an annular array around the axial direction (Ax) so as to pick up an axial magnetic flux generated by the stator (7) (Fig. 2). In this embodiment, the piston mechanism comprises a piston head (21) and a piston rod (22) which is pivotably connected to the piston head (21) (Fig. 2). The piston rod (22) is coupled to an upper surface (23) of mounting disc (18) via the pivot (10) that is eccentrically mounted to the mounting disc (18). In this embodiment, the cylinder block (4) is arranged above the rotor (8) and the stator (9) is arranged below the below the rotor (8) (Fig. 2).
In another embodiment, the stator (7) comprises a plurality of winding coils (24) which are mounted onto pedestals (25) arranged on a bottom of the casing (3) and along an annular array around the axial direction (Ax) so as to oppose the plurality of magnets (Fig. 2).
In another embodiment, the casing (3) is configured by an upper part (3a) and a lower part (3b) (Fig. 2). In this embodiment, the cylinder block (4) is fixed to the upper part (3a) of the casing (3) (Fig. 2). In this embodiment, the stator (7) is fixed to the lower part (3b) of the casing (3) (Fig. 2). In this embodiment, the support mechanism is also mounted to the lower part (3b) of the casing (3) (Fig. 2).
In another embodiment, the compressor (1) comprises a suction silencer (26) which is arranged in an upper part (3a) of the casing (3) for drawing refrigerant from a refrigeration circuit through an intake conduit (27) (Fig. 2). In this embodiment, the compressor (1) further comprises an intake port (28) which fluidly connects the chamber (5) and the suction silencer (26) (Fig. 2).
In another embodiment, the intake conduit (27) is arranged on an upper wall (29) of the upper part (3b) of the casing (3) (Fig. 2).
In another embodiment, the cylinder block (4) has a cylinder head (30) which is configured to exhaust the compressed refrigerant from the chamber (5) to a refrigeration circuit of an refrigeration appliance via an exhaust port (31) and exhaust conduit (32) (Fig. 2). In this embodiment, the cylinder head (30) is arranged on a lateral wall (33) of the upper part (3a) of the casing (3) (Fig. 2).
In another embodiment, the refrigeration appliance of the present invention is a domestic refrigerator (2) which comprises a refrigeration compartment for refrigerating articles and a refrigeration circuit for refrigerating the refrigeration compartment (Fig. 4). The refrigeration circuit comprises a compressor (1) of the present invention, a condenser (34), an expansion valve (35), and an evaporator which are serially connected to circulate a refrigerant. The compressor is placed in a lower cabinet (36) (Figs. 3 and 4).
By the present invention, a compressor (1) with a reduced size and an improved shape has been attained. The compressor (1) of the present invention has especially a relatively small height and a generally flat shape. Thereby the utilizable volume for the refrigeration compartments has been increased.

Claims

A compressor (1) for use in a refrigeration appliance, in particular a domestic refrigerator (2), the compressor (1) comprising a casing (3) which includes - a cylinder block (4) which has a chamber (5) for compressing a refrigerant,

- a piston mechanism for compressing the refrigerant in the chamber (5),

- an electrical motor (6) for driving the piston mechanism,

characterized in that

- the motor (6) has a stator (7) and a rotor (8) which are separated by a gap (9) in an axial direction (Ax) that is perpendicular to a rotation plane of the rotor (8),

wherein the rotor (8) is rotatably secured to the casing (3) via a support mechanism which is separately provided from the cylinder block (4) and the piston mechanism, and

wherein the piston mechanism is coupled to the rotor (8) via a pivot (10) that is eccentrically mounted to the rotor (8).
The compressor (1) according to claim 1, characterized in that the support mechanism comprising an annular bearing (11) which is configured to rotatably support the rotor (8) and a supporting member (12) which is configured to support the annular bearing (11), wherein the supporting member (12) is directly fixed to the casing (3).
The compressor (1) according to claim 2, characterized in that

- the rotor (8) is annular shaped and has an inner flange (13) that is fixed to an inner ring of the annular bearing (11) and

- the supporting member (12) is annular shaped and has an outer flange (14) that is fixed to an outer ring of the annular bearing (11), wherein the annular rotor (8), the annular bearing (11) and the annular supporting member (12) together define an annular passage (15) for oil.
The compressor (1) according to claim 3, characterized in that an oil conduit (16) for conveying oil from a bottom of the casing (3) to a vicinity of the piston mechanism, wherein the oil conduit (16) is fixed to an annular opening (17) of the rotor (8)
The compressor (1) according to claim 4, characterized in that the oil conduit (16) is funnel shaped and has two open ends (16a; 16b) which are in fluid communication, wherein a smaller open end (16a) is immersed in the oil that is accumulated in a bottom of the casing (3).
The compressor (1) according to claim to any one of claims 1 to 5, characterized in that the rotor (8) comprising a position adjusting mechanism configured to adjust a position of the pivot (10) in a radial direction which is perpendicular to the axial direction (Ax).
The compressor (1) according to any one of claims 1 to 6, characterized in that the pivot (10) is a cylindrical shaped pin which is formed on the rotor (8), wherein the pin extends in an axial direction (Ax).
The compressor (1) according to any one of claims 1 to 7, characterized in that

- the rotor (8) comprising a mounting disc (18) which is rotatably arranged around the axial direction (Ax) and which has a lower surface (19) parallel to the rotation plane and a plurality of permanent magnets (20) which are fixed onto the lower surface (19) along an annular array around the axial direction (Ax) so as to pick up an axial magnetic flux generated by the stator (7),

- the piston mechanism comprising a piston head (21) and a piston rod (22) which is pivotably connected to the piston head (21), wherein the piston rod (22) is coupled to an upper surface (23) of the mounting disc (18) via the pivot (10) that is eccentrically mounted to the mounting disc (18),

- the cylinder block (4) is arranged above the rotor (8) and

- the stator (9) is arranged below the rotor (8).
The compressor (1) according to claim 8, characterized in that the stator (7) comprising a plurality of winding coils (24) which are respectively mounted onto pedestals (25) arranged on a bottom of the casing (3) along an annular array around the axial direction (Ax) so as to oppose the plurality of permanent magnets (20).
The compressor (1) according to any one of claims 1 to 9, characterized in that

the casing (3) is configured by an upper part (3a) and a lower part (3b), wherein the cylinder block (4) is fixed to the upper part (3a) of the casing (3), wherein the stator (7) is fixed to the lower part (3b) of the casing (3), and wherein the support mechanism is mounted to the lower part (3b) of the casing (3).
The compressor (1) according to claim 10, characterized in that

- a suction silencer (26) which is arranged in an upper part (3a) of the casing (3) for drawing refrigerant from a refrigeration circuit through an intake conduit (27) and

- an intake port (28) which is configured to fluidly connect the chamber (5) and the suction silencer (26).
The compressor (1) according to claim 11, characterized in that the intake conduit (27) is arranged on an upper wall (29) of the upper part (3b) of the casing (3).
The compressor (1) according to any one of claims 10 to 12, characterized in that the cylinder block (4) has a cylinder head (30) which is arranged to exhaust the compressed refrigerant from the chamber (5) to a refrigeration circuit of an refrigeration appliance via an exhaust port (31) and an exhaust conduit (32), wherein the cylinder head (30) is arranged on a lateral wall (33) of the upper part (3a) of the casing (3).
A refrigeration appliance, in particular a domestic refrigerator (2), comprising a refrigeration compartment for refrigerating articles and a refrigeration circuit for refrigerating the refrigeration compartment, wherein the refrigeration circuit includes a compressor (1) according to any one of claims 1 to 13, a condenser (34), an expansion valve (35) and an evaporator serially connected to circulate a refrigerant, wherein the compressor is placed in a lower cabinet (36).