EP2433005A1

EP2433005A1 - Hermetic compressor having increased lubrication effectiveness

Info

Publication number: EP2433005A1
Application number: EP10719002A
Authority: EP
Inventors: Muhterem Ertoy; Bilgin Hacioglu
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2009-05-22
Filing date: 2010-05-13
Publication date: 2012-03-28
Also published as: WO2010133508A1; BRPI1010818A2; CN102439315A

Abstract

Compressor (1) comprising: a casing (2) containing lubricant therein; a motor (3) placed in the casing (2) consisting of two main parts, namely a stator (4) and a rotor (5); a crankshaft (6) that transmits the motion received from the motor (3); an oil suction pipe (7) secured to the end of the crankshaft (6) having a helical shaped protrusion (8) surrounding the outer surface of its end remaining in the lubricant inside the casing (2); and a cylindrical receptacle (11) secured to the casing (2), into which the end of the oil suction pipe (7) is inserted, which encircles the protrusion (8) such that a gap is left there between.

Description

HERMETIC COMPRESSOR HAVING INCREASED LUBRICATION EFFECTIVENESS

[0001] The present invention relates to a compressor wherein the lubrication performance is increased.

[0002] The hermetic compressors utilized preferably in refrigerators provide the circulation of the refrigerant utilized for refrigeration. In this type of compressors, lubrication is performed for decreasing the friction losses of the movable components of the compressor during operation, for preventing abrasion and removing the heat resulting from friction. The process of lubricant delivery to the movable components and the bearings is realized by means of an oil suction pipe. The lubricant at the base of the compressor casing at a certain level is sucked by means of the oil suction pipe and delivered to the bearings and the compressor components that need to be lubricated. The oil sucked from the inlet orifice at the lower side of the oil suction pipe, which is situated at the end of the crank shaft and rotates together with the crank shaft, moves forward on the inner surfaces of the oil suction pipe by the effect of centrifugal force as a result of the rotating crank shaft.

[0003] When the compressor operates particularly at low speeds, the crank also rotates at low speed and a sufficient amount of lubricant cannot be sucked as the centrifugal force decreases. Problems such as heating, abrasion may arise due to insufficient oil suction. Moreover, even in normal operational speeds, in the case oil suction does not have the desired flow rate, problems may arise in lubricating the piston rod-crankpin and the piston-cylinder bearings.

[0004] In the state of the art United States Patent Document No. US4750864, a compressor is explained comprising an impeller mounted on the oil pick up tube wherein the lubrication is improved.

[0005] In the state of the art International Patent Application No. WO00/77400, a compressor comprising a closed vessel fixed on the base of the casing wherein the end of the oil guide enters is explained.

[0006] In the state of the art International Patent Application No WO2006085163, a compressor comprising a guide secured on the casing providing the lubricant to reach the oil suction pipe and the vortices created during suction of oil to be delivered upwards is explained.

[0007] In variable speed compressors, the lowest operatable speed is determined by the lubrication dynamics. The whole system performance of the compressor and the refrigerator increases as the lowest operatable value decreases. However, under conditions wherein particularly the variable speed compressors operate with low crank rotational speed, sufficient lubricant cannot be delivered to the required locations and lubrication cannot be performed. As a result of insufficient lubrication, the compressor performance decreases and the system safety is reduced due to abrasions and therefore the life of the compressor is shortened. Therefore in variable speed compressors, it is important to increase the effectiveness of an efficient lubrication at low speeds.

[0008] The aim of the present invention is the realization of a compressor wherein the effectiveness of lubrication is increased particularly at low speeds.

[0009] The compressor realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof, comprises a helically shaped protrusion that surrounds the end of the oil suction pipe all around and a receptacle with an open top wherein this end of the oil suction pipe is inserted, which is secured to the casing and which encircles the protrusion such that a gap is left therebetween.

[0010] The protrusion encircles the end of the oil suction pipe uninterrupted and at least wrapping for a complete round.

[0011] Thus, not the almost inactive lubricant at the inlet of the oil suction pipe but the lubricant that is pushed by the protrusion up to the inlet, as a result of the rotating oil suction pipe and reaching a certain speed, is enabled to be sucked by the oil suction pipe.

[0012] The protrusion comprises a flow surface extending downwards slopingly and a barrier surface which intersects this surface, which extends vertically from the oil suction pipe towards the receptacle wall. The flow surface accelerates the downward flow of the lubricant by means of its slope and the barrier surface prevents the lubricant pushed downward by rotation of the oil suction pipe from rising upward. Consequently by means of this configuration of the protrusion, a forced lubricant flow is created, thus providing to guide the lubricant toward the inlet of the oil suction pipe in a single direction.

[0013] When the end of the oil suction pipe enters into the receptacle, a gap is left between the receptacle walls and the protrusion. The distance of this gap is of critical importance for enabling the lubricant to be effectively sucked in by the oil suction pipe. The gap has to be large enough for not allowing the protrusions on the oil suction pipe from rubbing against the receptacle walls, however small enough for guiding the lubricant toward the inlet of the oil suction pipe. The gap is preferably between the values of 0,1 mm to 5 mm. By means of the gap, the flow rate of the lubricant is increased and lubricant moving with a greater speed is provided to reach to the oil suction pipe inlet and this lubricant sucked by the oil suction pipe at a high speed is provided to be sucked in. This facilitates the heat generated inside the compressor to be discharged by means of the lubricant out of the compressor by accelerating the circulation of the lubricant.

[0014] In another embodiment of the present invention, the oil suction pipe has a protrusion form not during its production but by mounting an intermediate element with a protrusion on its side walls to the end of the oil suction pipe.

[0015] In another embodiment of the present invention, an element produced from elastic material on the side walls of the receptacle or on the base of the intermediate element is utilized in order to attenuate the forces that may result from the oil suction pipe impacting the receptacle walls due to the vibrations generated during operation of the compressor.

[0016] By means of the present invention, the lubrication problem arising at low crankshaft rotating speeds of particularly variable speed compressors is overcome and the performance of the whole system is improved. Moreover, the life expectancy problem of the compressor at low speeds is eliminated and mechanical losses are decreased.

[0017] A compressor realized in order to attain the aim of the present invention is illustrated in the attached figures, where: [0018] Figure 1 - is the schematic view of a compressor.

[0019] Figure 2 - is the detailed view of the compressor.

[0020] Figure 3 - is the sideways view of the intermediate element..

[0021] Figure 4 - is the sideways perspective view of the intermediate element..

[0022] Figure 5 - is the cross sectional view of the intermediate element..

[0023] Figure 6 - is the cross-sectional view of the intermediate element in another embodiment of the present invention. [0024] Figure 7 - is the perspective view of the receptacle. [0025] Figure 8 - is the perspective view of the receptacle in another embodiment of the present invention. [0026] Figure 9 - is the detailed view of the compressor in another embodiment of the present invention. [0027] Figure 10 - is the detailed view of the compressor in yet another embodiment of the present invention. [0028] The elements illustrated in the figures are numbered as follows:

1. Compressor

2. Casing

3. Motor

4. Stator

5. Rotor

6. Crankshaft

7. Oil suction pipe

8. Protrusion

9. Flow surface

10. Barrier surface

11. Receptacle

12. Intermediate element

13. Elastic element

[0029] In household appliances, preferably in cooling devices, the circulation of the refrigerant utilized for refrigeration is provided by a reciprocating hermetic compressor (1). In this type of compressors, lubrication is performed for decreasing the friction losses in the movable components of the compressor (1) during operation, for preventing abrasion and for removing the heat resulting from friction.

[0030] The compressor (1) comprises a casing (2) containing lubricant therein, a motor (3) situated in the casing (2) which consists of two main parts, a stator (4) and a rotor (5), a crankshaft (6) that transmits the motion received from the motor (3), an oil suction pipe (7) secured to the end of the crankshaft (6), having a helical shaped protrusion (8) surrounding the outer surface of its end remaining in the lubricant inside the casing (2) and a cylindrical receptacle (11) secured to the casing (2) into which the end of the oil suction pipe (7) is inserted, encircling the protrusion (8) such that a gap is left therebetween (Figure 1 , Figure 2 and Figure 7).

[0031] The amount of lubricant sucked by the oil suction pipe (7) and delivered to the crankshaft (6) is increased by means of the protrusion (8) remaining under the lubricant level and the receptacle (11) into which the portion of the oil suction pipe (7) wherein the protrusion (8) is located is inserted. The oil suction pipe (7) and hence the protrusion (8) rotating together with the rotational movement of the crankshaft (6) virtually suck the lubricant from the upper portion of the receptacle (11) and pushes toward the lower portion of the receptacle (11). The lubricant reaching the lower portion of the receptacle (11) has no place else to go but the inlet (A) of the oil suction pipe (7) opening into the receptacle (11). Different from the other embodiments, the protrusion (8) located in the receptacle (11) pumps the lubricant received from the upper portion toward the lower portion. The only place the lubricant can escape upon reaching the inlet (A) of the oil suction pipe (7) is this inlet (A). The lubricant together with the rotational movement of the crankshaft (6) passes through the inlet (A) of the oil suction pipe (7) and is pumped upwards along its inner walls. Consequently, the protrusion (8) and the receptacle (11) function as an additional pump for the lubricant thus making it easier to deliver the lubricant upward and the lubricant can be carried upwards even in the low speed the compressor (1) operates and in the low speeds the crankshaft (6) rotates.

[0032] The outer surface of the oil suction pipe (7) is configured almost like a screw, the protrusion (8) comprises a flow surface (9) extending downwards slopingly from the oil suction pipe (7) to the receptacle (11) wall and a barrier surface (10) intersecting this surface (9), extending from the oil suction pipe (7) toward the receptacle (11) wall and vertical to the oil suction pipe (7). While the flow surface (9) accelerates the downward flow of the lubricant, the barrier surface (10) prevents the lubricant pushed downward by the protrusion (8) from rising upward. Due to this configuration of the protrusion (8), the lubricant is enabled to be guided toward the inlet (A) of the oil suction pipe (7) in a single direction (Figure 3, Figure 4 and Figure 5).

[0033] A gap is left between the receptacle (11) walls and the protrusion (8). The gap has to be large enough for not allowing the protrusions (8) on the oil suction pipe (7) from rubbing against the receptacle (11) walls, however small enough for guiding the lubricant toward the inlet (A) of the oil suction pipe (7). The gap is preferably between the values of 0,1 mm to 5 mm. By means of the gap, the circulation of the lubricant is accelerated and the discharging of the heat generated in the compressor (1) from the casing (2) out of the compressor (1) is facilitated by means of the lubricant. By improving the heat transfer of the compressor (1), the thermodynamic efficiency of the compressor (1) is also increased.

[0034] When the compressor (1) starts operating, the crankshaft (6) and the oil suction pipe (7) mounted thereto rotate around themselves in the lubricant inside the casing (2). As a result of this rotational movement, the protrusion (8) on the outer wall of the oil suction pipe (7) also rotates and due to its configuration, the lubricant received from the upper portion of the receptacle (11) is pushed toward the inlet (A) of the oil suction pipe (7). The lubricant passing through the gap between the protrusion (8) and the receptacle (11) walls passes through the only opening it can go, that is the inlet (A) of the oil suction pipe (7) and is pumped up toward the crankshaft (6).

[0035] In another embodiment of the present invention, the oil suction pipe (7) comprises an intermediate element (12) mounted to the end of the oil suction pipe (7) with a helical shaped protrusion (8) surrounding its side wall. By means of this embodiment, while the protrusion (8) can be directly formed during the production of the oil suction pipe (7), the protrusion (8) can also be formed by mounting an apparatus afterwards on the oil suction pipe (7).

[0036] In another embodiment of the present invention, the compressor (1) comprises an elastic element (13) on the receptacle (11) and/or the intermediate element (12) in order to keep the crankshaft (6) and the oil suction pipe (7) on its end in the same vertical axis due to the vibrations generated during operation. Accordingly, the forces generated as a result of the oil suction pipe (7) impacting the receptacle (11) walls due to the vibrations are attenuated. The elastic element (13) is situated on the receptacle (11) side walls or on the base of the intermediate element (12), between the protrusion (8) and the oil suction pipe (7) (Figure 6, Figure 8, Figure 9 and Figure 10).

[0037] By means of the present invention, particularly in variable speed compressors (1) the lubrication problem arising from low crankshaft (6) rotational speeds is overcome and the performance of the whole system is improved and on the other hand mechanical losses are decreased by alleviating the life expectancy problem of the compressor (1) at low speeds.

[0038] It is to be understood that the present invention is not limited to the embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These different embodiments should be considered within the scope of the claims of the present invention, too.

Claims

1. A compressor (1) comprising a casing (2) containing lubricant therein, a motor (3) placed in the casing (2) consisting of two main parts, namely a stator (4) and a rotor (5), a crankshaft (6) that transmits the motion received from the motor (3), an oil suction pipe (7) secured to the end of the crankshaft (6) for sucking the lubricant inside the casing (2), and characterized by

- an oil suction pipe (7) having a helical shaped protrusion (8) surrounding the outer surface of its end remaining in the lubricant inside the casing (2) and

- a cylindrical receptacle (11) secured to the casing (2), into which the end of the oil suction pipe (7) is inserted, which encircles the protrusion (8) such that a gap is left therebetween.

2. A compressor (1) as in Claim 1 , characterized by the protrusion (8) having a flow surface (9) extending downwards slopingly from the oil suction pipe (7) to the receptacle (11) wall and a barrier surface (10) intersecting this surface (9), extending from the oil suction pipe (7) toward the receptacle (11) wall and vertical to the oil suction pipe (7).

3. A compressor (1) as in Claim 1 or 2, characterized by the oil suction pipe (7) which has an outer surface configured like a screw.

4. A compressor (1) as in Claim 1 , characterized by the oil suction pipe (7) comprising an intermediate element (12) mounted to the end of the oil suction pipe (7) with a helical shaped protrusion (8) surrounding its side wall.

5. A compressor (1) as in Claim 1 , characterized by the elastic element (13) situated on the receptacle (11) side walls.

6. A compressor (1) as in Claim 4, characterized by the elastic element (13) situated on the base of the intermediate element (12), between the protrusion (8) and the oil suction pipe (7).