EP3250826A1

EP3250826A1 - Crankshaft for a hermetic compressor

Info

Publication number: EP3250826A1
Application number: EP15703749.0A
Authority: EP
Inventors: Bilgin Hacioglu; Tolga Yaroglu; Nazim Arda EYYUBOGLU
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2015-01-30
Filing date: 2015-01-30
Publication date: 2017-12-06
Anticipated expiration: 2035-01-30
Also published as: EP3250826B1; WO2016119869A1

Abstract

A crankshaft (1) for hermetically sealed reciprocating compressors (2), which have a cylinder block (3) with a main bearing (4) for supporting the crankshaft (1) and a casing (5) having a lower section (6) for collecting lubricant (7), comprises a vertically extending shaft (8) which includes an integral bearing section (9) that is adapted for being journalled into the main bearing (4). Said shaft (8) includes an integral lower tip section (10) that is adapted for being directly immersed into the lubricant (7) inside the lower section (6) and two axially upwardly diverging lubricant channels (11, 12) that are formed within the shaft (8) and adapted for conveying the lubricant (7) from the lower tip section (10) towards the surface of the bearing section (9) upon rotation of the shaft (8).

Description

CRANKSHAFT FOR A HERMETIC COMPRESSOR

CRANKSHAFT FOR A HERMETIC COMPRESSOR
The present invention relates to a crankshaft for use in a hermetically sealed reciprocating compressor of a refrigeration appliance which has a variable refrigeration capacity.
Hermetically sealed reciprocating compressors are commonly known. In such compressors, the lubrication of the bearing section is performed by the lubricant which is collected in the lubricant sump, in particular in the lower section of the hermetic casing. The lubricant is generally pumped from the lubricant sump towards the bearing section by means of a lubricant pickup tube under the action of centrifugal forces. The lubricant pickup tube is generally fixed to the lower tip section of the shaft and immersed into the lubricant sump. In general, the bearing section is fluidly connected with the pickup tube by means of a lubricant channel inside the shaft. The lubrication performance is of utmost importance. When the refrigeration appliance is operated at a comparatively low refrigeration capacity, the bearing section of the crankshaft generally receives less lubricant. Consequently, the surface of the bearing section wears rapidly and the life time of the compressor decreases. A drawback of the above mentioned prior art compressor is that the production and the assembly of the lubricant pickup tube generally increase the overall costs.
An objective of the present invention is to provide a crankshaft which overcomes the aforementioned drawbacks of the prior art in a cost effective way and which enables an improved lubrication performance.
This objective has been achieved by the crankshaft as defined in claim 1, the hermetically sealed reciprocating compressor as defined in claim 13 and the refrigeration appliance as defined in claim 14. Further achievements have been attained by the subject-matters respectively defined in the dependent claims.
The crankshaft of the present invention is provided without a lubricant pickup tube. In the crankshaft of the present invention, the shaft includes: an integral lower tip section that can be directly immersed into the lubricant inside the lower section of the casing and at least two axially upwardly diverging lubricant channels that are formed within the shaft. The lubricant channels convey the lubricant from the lower tip section towards the surface of the bearing section of the shaft upon rotation.
With the present invention, particularly by virtue of the divergent lubricant channels, the bearing section of the shaft can be sufficiently lubricated even at comparatively low rotational speeds. With the present invention, the need for using a lubricant pickup tube has also been obviated.
In an embodiment, the lower ends of the divergent lubricant channels open without intersecting each other into an oblong hole which is formed into the bottom of the lower tip section of the shaft. Due to the oblong hole, the divergent lubricant channels can be more easily formed into the shaft at comparatively larger angles to the rotational axis. Thereby, the lubrication performance can be increased. In addition, as the divergent lubricant channels have been prevented from intersecting each other, the formation of any sharp edges has also been prevented. Thereby, the risk of any cavitation damage can be eliminated or reduced as much as possible.
In another embodiment, the lower ends of the divergent lubricant channels are separated by a divider which is arranged into the oblong hole. Thereby, the lubrication performance can be further increased.
In an alternative embodiment, the oblong hole is partly concealed through a lid which has a centered round aperture. Thereby, the lubricant flows more smoothly from the lubricant sump into the oblong hole and therefrom into the divergent lubrication channels.
In another embodiment, the divergent lubricant channels are straight shaped and inclined at acute angles to the rotational axis of the shaft.
In another embodiment, the divergent lubricant channels are inclined at equal angles. In an alternative embodiment, the lubricant channels are inclined at different angles.
In another embodiment, the bearing section has at least two curved lubrication grooves which are fluidly connected with the upper ends of the divergent lubrication channels respectively for conveying and distributing the lubricant. The upper ends of the lubrication channels terminate below the bearing section. Thereby, the strength of the shaft, in particular the strength of bearing section has been increased.
In another embodiment, the curved lubrication grooves are helical shaped.
Additional advantages of the crankshaft and the hermetically sealed reciprocating compressor according to the present invention will become apparent with the detailed description of the embodiments with reference to the accompanying drawings in which:
Figure 1 – is a schematic cutaway view of a hermetically sealed reciprocating compressor which has the crankshaft according to an embodiment of the present invention;
Figure 2 – is a schematic perspective view of the crankshaft according to an embodiment of the present invention;
Figure 3 – is another schematic perspective view of the crankshaft according to an embodiment of the present invention;
Figure 4 – is a schematic bottom view of the crankshaft according to an embodiment of the present invention;
Figure 5 – is a schematic sectional view of the crankshaft according to an embodiment of the present invention, taken along the line A-A of Fig. 4;
Figure 6 – is a schematic perspective view of the crankshaft according to another embodiment of the present invention;
Figure 7 – is a schematic perspective view of the crankshaft according to another embodiment of the present invention;
Figure 8 – is a schematic perspective view of a divider used in the crankshaft of Fig. 6;
Figure 9 – is a schematic perspective view of a lid used in the crankshaft of Fig. 7.
The reference signs appearing on the drawings relate to the following technical features.

Crankshaft
Compressor
Cylinder block
Main bearing
Casing
Lower section
Lubricant
Shaft
Bearing section
Tip section
Channel
Channel
Hole
Side wall
Divider
Lid
Aperture
Groove
Groove
Passage
Passage
Crank
Passage
Intermediate section
Passage

The crankshaft (1) is suitable for use in a hermetically sealed reciprocating compressor (2) of a refrigeration appliance (not shown).
The compressor (2) comprises a cylinder block (3) which has a main bearing (4) for supporting the crankshaft (1) and a casing (5) which has a lower section (6) for collecting the lubricant (7). The lower section (6) defines a lubricant sump.
The crankshaft (1) comprises a vertically extending shaft (8) which includes an integral bearing section (9) that is adapted for being journalled into the main bearing (4) of the compressor (2).
In the crankshaft (1) of the present invention, the shaft (8) includes an integral lower tip section (10) that is adapted for being directly immersed into the lubricant (7) inside the lower section (6) and two axially upwardly diverging lubricant channels (11, 12) that are formed within the shaft (8). The axially upwardly diverging lubricant channels (11, 12) are adapted for conveying the lubricant (7) from the lower tip section (10) towards the surface of the bearing section (9) upon rotation of the shaft (8) (Fig 1 to 9).
The hermetically sealed reciprocating compressor (2) of the present invention comprises the crankshaft (1).
The refrigeration appliance of the present invention comprises the hermetically sealed reciprocating compressor (2).
In an embodiment, the shaft (8) further includes an oblong hole (13) which is formed into the bottom of the lower tip section (10). In this embodiment, the lower ends of the two lubricant channels (11, 12) open into the ceiling of the oblong hole (13) without intersecting each other. In addition, the opposing arc-shaped vertical side walls (14) of the oblong hole (13) are defined through the lower ends of the two lubricant channels (11, 12).
In another embodiment, a divider (15) is disposed between the lower ends of the two lubricant channels (11, 12) within the oblong hole (13). The divider (15) is a rectangular shaped flat piece.
In an alternative embodiment, a lid (16) is disposed onto the bottom of the lower tip section (10). In this alternative embodiment, the lid (16) has a centered round aperture (17) that fluidly connects the oblong hole (13) with the lubricant (7) inside the lower section (6).
In another embodiment, each lubricant channel (11, 12) is substantially straight shaped. In this embodiment, the lubricant channels (11, 12) are inclined at acute angles (α, β) to the rotational axis (z) of the shaft (8) respectively.
In another embodiment, the two lubricant channels (11, 12) are diametrically opposed. In this embodiment, the lubricant channels (11, 12) are inclined at equal angles (α, β) with respect to the rotational axis (z) of the shaft (8).
In another embodiment, the shaft (8) includes two curved lubrication grooves (18, 19) which are formed into the surface of the bearing section (9). These lubrication grooves (18, 19) are adapted for conveying the lubricant (7). In this embodiment, the lubrication grooves (18, 19) extend from the lower part of the bearing section (9) up to the upper part of the bearing section (9). In addition, the lower ends of the lubrication grooves (18, 19) are fluidly connected with the upper ends of the two lubrication channels (11, 12) respectively.
In another embodiment, the two curved lubrication grooves (18, 19) are helical shaped.
In another embodiment, the shaft (8) further includes two radially extending lower lubrication passages (20, 21) which are formed into the shaft (8). These lower lubrication passages (20, 21) fluidly connect the lower ends of the lubrication grooves (18, 19) with the upper ends of the two lubrication channels (11, 12) respectively.
In another embodiment, the shaft (8) has a third lubricant channel (not shown) which is formed within the shaft (8). The third lubricant channel is adapted for conveying the lubricant (7) from the upper part of the bearing section (9) to the surface of the crank (22) upon rotation of the shaft (8). In this embodiment, the two curved lubrication grooves (18, 19) join at the upper part of the bearing section (9) and are fluidly connected with the third lubrication channel.
In another embodiment, the shaft (8) includes a radially extending upper lubrication passage (23) which is formed into the shaft (8). The upper lubrication passage (23) fluidly connects the joined lubrication grooves (18, 19) with the third lubrication channel.
In another embodiment, the shaft (8) includes an integral intermediate section (24) which joins the integral bearing section (9) and the integral lower tip section (10) and a refrigerant discharge passage (25) which is formed into the intermediate section (24). The refrigerant discharge passage (25) is fluidly connected with the radial inner section of the two lubrication channels (11, 12) and allows exclusively the refrigerant to escape into the casing (5).
In another embodiment, the refrigeration appliance is provided as a domestic refrigerator.

Claims

A crankshaft (1) for use in a hermetically sealed reciprocating compressor (2) of a refrigeration appliance, the compressor (2) comprising a cylinder block (3) which has a main bearing (4) for supporting the crankshaft (1) and a casing (5) which has a lower section (6) for collecting lubricant (7), the crankshaft (1) comprising a vertically extending shaft (8) which includes an integral bearing section (9) that is adapted for being journalled into the main bearing (4), the crankshaft (1) being characterized in that the shaft (8) comprising an integral lower tip section (10) that is adapted for being directly immersed into the lubricant (7) inside the lower section (6) and two axially upwardly diverging lubricant channels (11, 12) that are formed within the shaft (8) and adapted for conveying the lubricant (7) from the lower tip section (10) towards the surface of the bearing section (9) upon rotation of the shaft (8).
The crankshaft (1) according to claim 1, characterized in that the shaft (8) comprising an oblong hole (13) which is formed into the bottom of the lower tip section (10), wherein the lower ends of the two lubricant channels (11, 12) open into the ceiling of the oblong hole (13) without intersecting each other and wherein the opposing arc-shaped vertical side walls (14) of the oblong hole (13) are defined through the lower ends of the two lubricant channels (11, 12).
The crankshaft (1) according to claim 2, characterized in that a divider (15) which is disposed between the lower ends of the two lubricant channels (11, 12) within the oblong hole (13).
The crankshaft (1) according to claim 2, characterized in that a lid (16) which is disposed onto the bottom of the lower tip section (10), wherein the lid (16) has a centered round aperture (17) that fluidly connects the oblong hole (13) with the lubricant (7) inside the lower section (6).
The crankshaft (1) according to any one of claims 1 to 4, characterized in that each lubricant channel (11, 12) is substantially straight shaped and inclined at an acute angle (α, β) to the rotational axis (z) of the shaft (8).
The crankshaft (1) according to claim 5, characterized in that the two lubricant channels (11, 12) are diametrically opposed and inclined at equal angles (α, β) with respect to the rotational axis (z) of the shaft (8).
The crankshaft (1) according to any one of claims 1 to 6, characterized in that the shaft (8) comprising two curved lubrication grooves (18, 19) which are formed into the surface of the bearing section (9), wherein the lubrication grooves (18, 19) extend from the lower part of the bearing section (9) up to the upper part of the bearing section (9) and are adapted for conveying the lubricant (7) and wherein the lower ends of the lubrication grooves (18, 19) are fluidly connected with the upper ends of the two lubrication channels (11, 12) respectively.
The crankshaft (1) according to claim 7, characterized in that the two curved lubrication grooves (18, 19) are helical shaped.
The crankshaft (1) according to claim 7 or 8, characterized in that the shaft (8) comprising two radially extending lower lubrication passages (20, 21) which are formed into the shaft (8), wherein the lower lubrication passages (20, 21) fluidly connect the lower ends of the lubrication grooves (18, 19) with the upper ends of the two lubrication channels (11, 12) respectively.
The crankshaft (1) according to any one of claims 7 to 9, characterized in that the shaft (8) has an integral crank (22) adapted for converting rotational movement in reciprocating movement and a third lubricant channel which is formed within the shaft (8) and adapted for conveying the lubricant (7) from the upper part of the bearing section (9) to the surface of the crank (22) upon rotation of the shaft (8), wherein the two curved lubrication grooves (18,19) join at the upper part of the bearing section (9) and are fluidly connected with the third lubrication channel.
The crankshaft (1) according to claim 10, characterized in that the shaft (8) comprising a radially extending upper lubrication passage (23) which is formed into the shaft (8), wherein the upper lubrication passage (23) fluidly connects the joined lubrication grooves (18, 19) with the third lubrication channel.
The crankshaft (1) according to any one of claims 1 to 11, characterized in that the shaft (8) comprising an integral intermediate section (24) which joins the bearing section (9) and the lower tip section (10) and a refrigerant discharge passage (25) which is formed into the intermediate section (24), wherein the discharge passage (25) is fluidly connected with the radial inner section of the two lubrication channels (11, 12) and adapted for allowing the refrigerant to escape into the casing (5).
A hermetically sealed reciprocating compressor (2) for use in a refrigeration appliance, the compressor (2) comprising a cylinder block (3) which has a main bearing (4) for supporting a crankshaft (1) and a casing (5) which has a lower section (6) for collecting the lubricant (7) and characterized in that the crankshaft (1) as defined in any one of claims 1 to 12, wherein the bearing section (9) of the shaft (8) is journalled into the main bearing (4) and wherein the lower tip section (10) of the shaft (8) is directly immersed into the lubricant (7) inside the lower section (6) of the casing (5).
A refrigeration appliance, in particular a domestic refrigerator characterized in that the hermetically sealed reciprocating compressor (2) as defined in claim 13.