WO2009132932A1

WO2009132932A1 - A compressor with improved refrigerant flow performance

Info

Publication number: WO2009132932A1
Application number: PCT/EP2009/054140
Authority: WO
Inventors: Bilgin Hacioglu; Umit Fidan
Original assignee: Arcelik Anonim Sirketi
Priority date: 2008-05-01
Filing date: 2009-04-07
Publication date: 2009-11-05
Also published as: ES2547407T3; EP2300715B1; EP2300715A1; SI2300715T1

Abstract

The present invention relates to a hermetic compressor (1 ), used in household appliances, preferably in cooling devices. The compressor (1 ) comprises a cylinder (2) wherein the refrigerant is received, a cylinder head (3) disposed on the cylinder (2), a valve table (4) whereon the cylinder head (3) is emplaced, a discharge hole (5) on the valve table (4) wherefrom the refrigerant received into the cylinder (2) is discharged, a piston (6) disposed inside the cylinder (2) that activates the refrigerant by reciprocating inside the cylinder (2) and a protrusion (7) arranged on the piston (6) that is seated in the discharge hole (5) when the piston (6) reaches the top dead center.

Description

Description A COMPRESSOR WITH IMPROVED REFRIGERANT FLOW PERFORMANCE

[0001] The present invention relates to a compressor wherein the flow performance of the refrigerant left in the cylinder during the pumping of the refrigerant is improved.

[0002] In the hermetic compressors utilized particularly in refrigerators, a piston is provided for suction of the refrigerant and a cylinder wherein the piston is disposed. A valve table is provided on the cylinder whereon the suction and discharge holes are arranged. In the suction process, the piston receives the refrigerant from the suction hole by reciprocating inside the cylinder and afterwards reciprocates for compressing and pumping the refrigerant through the discharge hole out of the cylinder. One of the criteria for efficient operation of the compressor is the rate of the refrigerant, received into the cylinder in one cycle, discharged out of the cylinder. However, when the piston compresses the refrigerant, all of the refrigerant cannot be discharged from the discharge hole out of the cylinder and the compressor yield decreases. In the state of the art, a lot of patent documents explain how to decrease the dead space formed in the cylinder cavity that affects the volumetric efficiency, the refrigerant volume left in the cylinder without being discharged when the piston reaches the top point.

[0003] In an ideal compressor embodiment, the dead space is zero. As the amount of the dead space increases, the compressor efficiency decreases. The reason for this is that, despite consuming energy for discharging the entire refrigerant inside the cylinder by compressing the piston in the entire cylinder volume, the refrigerant equaling to the dead space cannot be discharged out of the cylinder.

[0004] In the state of the art French Patent Document No FR2617242, a boss arranged on one face of the piston that is seated in the delivery orifice occupies the greater part of the dead space during the compression of the refrigerant. The boss and the delivery orifice can be configured of matching cylindrical or frustoconical shapes. Since the cross section through which the refrigerant passes gets narrower as the boss is seated in the delivery orifice and since the boss closes the entire delivery orifice, as a result of formed turbulences, the discharge of the refrigerant gets difficult and losses increase. Some part of the gain by decreasing the dead space is lost by making the flow difficult.

[0005] In the state of the art United States of America Patent No US5816783 a projection formed on the top of the piston and the discharge port are configured to be frustoconical. Since the gradient of the conical surface of said projection is smaller than that of the side wall of the said discharge port, the narrowness of the cross section formed by the projection being seated inside the discharge port is partially decreased.

[0006] In the state of the art International Patent Application No WO2005010365, a compressor is explained comprising a piston with a projection that is eccentrically seated in the outlet orifice.

[0007] In the state of the art United States of America Patent No US6623258, a compressor is explained wherein a flow channel is formed between the projection and the walls of the outlet opening.

[0008] In all these embodiments, projections are provided on the piston that decrease the dead space without obstructing passage of the refrigerant until the piston reaches the top dead center and enter into the discharge port when the piston reaches the top dead center. These projections used with the aim of reducing the dead space result in narrowing of the refrigerant flow path at a specific rate towards the end of the compression cycle. The refrigerant accelerates while passing through this narrowed cross section, the temperature rises and the pressure decreases. This results in reduction of the compressor yield.

[0009] The aim of the present invention is the realization of a compressor wherein the flow of the refrigerant through the cylinder to the discharge hole is improved.

[0010] The compressor realized in order to attain the aim of the present invention, explicated in the first claim and the respective claims thereof, comprises at least one groove on the lateral surfaces of the protrusion arranged on the piston, extending from the piston surface towards the top end of the protrusion. [0011] When the piston reaches the top dead center, that is when the piston surface is at the nearest position to the valve table, the protrusion is partially seated in the discharge hole. By means of the grooves formed on the protrusion, the sudden narrowing of the flow path cross section is prevented and the refrigerant flow from the discharge hole is convenient, with a controllable discharge and without creating much dead space. The sudden increase of the refrigerant acceleration and the temperature and respectively the decrease in yield by the reducing of pressure is prevented. Furthermore, the groove guides the refrigerant towards the discharge hole and shapes the flow of the refrigerant.

[0012] In another embodiment of the present invention, the groove is formed on the portion of the protrusion near the cylinder axis. Accordingly, refrigerant flow can be improved in the region wherein the refrigerant flow is intense.

[0013] In another embodiment of the present invention, the sides of the groove extend parallel to each other. In this embodiment, the groove sides can either be parallel to the protrusion axis or can be inclined with a certain angle therebetween.

[0014] In an alternative embodiment of the present invention, the groove has a cross section that gets narrower from the piston surface towards the top of the protrusion. Accordingly, the speed of flow that slows when the piston reaches the top dead center is accelerated.

[0015] In another alternative embodiment of the present invention, the groove has a depth that increases from the piston surface towards the top of the protrusion.

[0016] By means of the present invention, the dead space is minimized by improving the refrigerant flow. This results in the increase of the compressor efficiency.

[0017] A compressor realized in order to attain the aim of the present invention is illustrated in the attached drawings, where:

[0018] Figure 1 - is the schematic view of a compressor.

[0019] Figure 2 - is the perspective view of the protrusion in an embodiment of the present invention.

[0020] Figure 3 - is the perspective view of the protrusion in another embodiment of the present invention. [0021] Figure 4 - is the perspective view of the protrusion in an alternative embodiment of the present invention. [0022] Figure 5 - is the perspective view of the protrusion in another alternative embodiment of the present invention. [0023] Figure 6 - is the perspective view of the protrusion in yet another alternative embodiment of the present invention. [0024] Figure 7 - is the perspective view of the protrusion in yet another alternative embodiment of the present invention. [0025] Figure 8 - is the cross sectional view when the protrusion is inside the hole. [0026] The elements illustrated in the figures are numbered as follows:

1. Compressor

2. Cylinder

3. Cylinder head

4. Valve table

5. Discharge hole

6. Piston

7. Protrusion

8. Groove

[0027] In household appliances, preferably in cooling devices, the circulation of the refrigerant fluid that is utilized for cooling is maintained by a hermetic compressor (1) having a piston.

[0028] The compressor (1) comprises a cylinder (2) wherein the refrigerant is received, a cylinder head (3) disposed on the cylinder (2), a valve table (4) whereon the cylinder head (3) is emplaced, a discharge hole (5) on the valve table (4) wherefrom the refrigerant received into the cylinder (2) is discharged, a piston (6) disposed inside the cylinder (2) that activates the refrigerant by reciprocating inside the cylinder (2) (Figure 1).

[0029] The compressor (1) comprises a protrusion (7) arranged on the piston (6) that is seated in the discharge hole (5) when the piston (6) reaches the top dead center, and at least one groove (8) on the lateral surface of the protrusion (7). The groove (8) extends from the surface of the piston (6) towards the top of the protrusion (7).

[0030] As the dead space decreases with the protrusion (7) having a groove (8) thereon, the flow of the refrigerant in the cylinder (2) is improved and the flow losses are reduced.

[0031] When the compressor (1) operates, the motion of the motor is transferred by the crank-piston rod-crank pin (not shown in the figures) to the piston (6), maintaining the piston (6) to reciprocate within the cylinder (2). The refrigerant within the cylinder (2) is compressed with the reciprocating motion of the cylinder (2). The refrigerant received into the cylinder (2) through the entrance hole (not shown in the figures) on the valve table (4), is compressed by the piston (6) for reaching the intended pressure. With the opening of the discharge valve (not shown in the figures) covering the discharge hole (5), the refrigerant passes through the discharge hole (5) and reaches the cylinder head (3). The compression process of the refrigerant is performed as the piston (6) starts to approach near the top dead center. In the last stages of the compression process, that is when the protrusion (7) starts to enter into the discharge hole (5), the grooves (8) formed on the protrusion (7) prevent the sudden decrease in the cross section wherein the flow takes place as the protrusion (7) enters into the discharge hole (5) and maintains the discharge of the refrigerant from the discharge hole (5) controllably (Figure 8). Accordingly, the temperature rise of the refrigerant with sudden increase in acceleration and the decrease of pressure are prevented. When the piston (6) reaches the top dead center, the discharge of the refrigerant from the discharge hole (5) continues by means of the grooves (8) and the dead space in the cylinder (2) is minimized. The flow of the refrigerant is controlled by means of the grooves (8) formed on the protrusion (7).

[0032] In an embodiment of the present invention, the protrusion (7) is cylinder shaped.

[0033] In another embodiment of the present invention, the protrusion (7) is configured frustoconically (Figure 2 to Figure 7).

[0034] In another embodiment of the present invention, the protrusion (7) comprises a groove (8) formed on the region thereof near the cylinder (2) axis (Figure 6 and Figure 7). [0035] In yet another embodiment of the present invention, both sides of the groove (8) extend parallel to each other (Figure 3 and Figure 4). In this embodiment of the present invention, the sides of the groove (8) are inclined such that they remain parallel to each other (Figure 5). [0036] In an embodiment of the present invention, the groove (8) has a cross section that gets narrower from the surface of the piston (6) towards the top of the protrusion (7) (Figure 2). [0037] In another embodiment of the present invention, the groove (8) has a depth that increases from the surface of the piston (6) towards the top of the protrusion (7) (Figure3). [0038] In an embodiment of the present invention, the protrusion (7) and the groove (8) are produced in one piece. [0039] In another embodiment of the present invention, the protrusion (7) is mounted on the piston (6) to be fully overlapping with the surface of the piston (6). [0040] By means of the present invention, as the dead space is minimized, the refrigerant flow within the cylinder (2) is improved by means of the groove

(8) and the flow losses are reduced. Accordingly, much more refrigerant can be discharged from the cylinder (2). This results in the increase of the compressor (1) efficiency.

Claims

1. A compressor (1) that comprises a cylinder (2) wherein the refrigerant is received, a cylinder head (3) disposed on the cylinder (2), a valve table (4) whereon the cylinder head (3) is emplaced, a discharge hole (5) on the valve table (4) wherefrom the refrigerant received into the cylinder (2) is discharged, a piston (6) disposed inside the cylinder (2) that activates the refrigerant by reciprocating inside the cylinder (2) and a protrusion (7) arranged on the piston (6) that is seated in the discharge hole (5) when the piston (6) reaches the top dead center, and characterized by at least one groove (8) arranged on the lateral surface of the protrusion (7).

2. A compressor (1) as in Claim 1 , characterized by a groove (8) that extends from the surface of the piston (6) towards the top of the protrusion (7).

3. A compressor (1) as in Claim 1 or 2, characterized by a groove (8) that is formed on the region of the protrusion (7) near the cylinder (2) axis.

4. A compressor (1) as in Claim 2 or 3, characterized by a groove (8) with both sides extending parallel to each other.

5. A compressor (1) as in Claim 2 or 3, characterized by a groove (8) with the sides extending slopingly.

6. A compressor (1) as in any one of the Claims 1 to 4, characterized by a groove (8) having a cross section that gets narrower from the surface of the piston (6) towards the top of the protrusion (7).

7. A compressor (1) as in any one of the Claims 1 to 4, characterized by a groove (8) having a depth that increases from the surface of the piston (6) towards the top of the protrusion (7).