WO2011023810A1

WO2011023810A1 - Variable capacity hermetic compressor

Info

Publication number: WO2011023810A1
Application number: PCT/EP2010/062593
Authority: WO
Inventors: Husnu Kerpicci; Serkan Ozsahin
Original assignee: Arcelik Anonim Sirketi
Priority date: 2009-08-31
Filing date: 2010-08-27
Publication date: 2011-03-03
Also published as: SI2473738T1; EP2473738B1; ES2428012T3; EP2473738A1

Abstract

The present invention relates to a hermetic compressor (1) comprising a casing (2), a motor (3), a crankshaft (4), an oil pickup tube (5) which is connected to the crankshaft (4) and the lower end of which is immersed into oil inside the casing (2), and which sucks and delivers the oil to the crankshaft (4), more than one carrier spring (6) which are fixed to the lower side inside the casing (2) and which carry the motor (3), a platform (7) which is fixed to the lower side inside the casing (2) and which bears the oil pickup tube (5) lower end, through which the oil pickup tube (5) sucks the oil, by means of a hole situated at its center, and a speed control unit (8) which provides the speed of the motor (3) to be changed according to varying operating conditions; wherein the lubrication efficiency of the movable components is increased.

Description

VARIABLE CAPACITY HERMETIC COMPRESSOR

[0001] The present invention relates to a hermetic compressor with variable

capacity (VCC), the lubrication conditions of the movable components of which are improved.

[0002] In hermetic compressors used in refrigerators, the performance of the oil pump, which provides the lubrication of the journal bearings wherein the crankshaft operates and also the cooling of the compressor components, considerably affects the amount of oil fed to the bearings and accordingly the lubrication effectiveness in the bearings and therefore, the mechanical efficiency of the compressor. Decline of the mechanical efficiency causes the input power to increase and the Coefficient of Performance (COP) to decrease. When the efficiency of the oil pump decreases, the amount of oil pumped by the oil pump decreases and the compressor causes the casing inner temperature and therefore the temperature of the refrigerant fluid circulated in the refrigeration cycle to increase. The increase of the refrigerant fluid temperature adversely affects the thermodynamic efficiency of the compressor. Apart from that, abrasions occur at the initial starting moment, at which the compressor changes from the stop position to the operating position, since the sufficient amount of oil cannot be fed to movable components such as crankshaft bearings. In variable capacity compressors, the capacity of the compressor is controlled according to the rotational speed of the motor and in case of a need for low capacity, the compressor motor is operated at low speed and in case of a need for high capacity, the compressor motor is operated at high speed. When the compressor motor is operated at low speed, the sufficient amount of oil cannot be fed by the oil pump and abrasions occur at crankshaft bearings that will affect the service life.

[0003] In the state of the art Japanese Patent Document No JP58018577, the lubricating mechanism in a compressor is explained. In order to prevent an overfeeding of oil as well as lowering the operating input under low ambient temperature conditions, a temperature sensor member that can change shape is connected between the crankshaft and the oil feed pipe, and the amount of immersion of the oil feed pipe, whereto the temperature sensor member is connected, into lubricating oil can be changed.

[0004] In the state of the art International Patent Application No WO2007043754, in a variable capacity compressor, oil pickup blades are disposed which are mounted to the crankshaft for the lubrication of the frictional surfaces of the movable components inside the compressor with suitable amount of oil, and which provide the oil to be pumped upwards into the oil pickup tube, according to the varying motor speeds.

[0005] The aim of the present invention is the realization of a hermetic

compressor with variable capacity, the lubrication conditions of the movable components of which are improved according to the varying motor speeds.

[0006] The hermetic compressor realized in order to attain the aim of the present invention is of variable capacity type and comprises a speed control unit that provides the speed of the motor to be changed according to varying operating conditions, and an actuator that is activated and deactivated by the speed control unit and hence moves the oil pickup tube in the vertical direction and thus, provides the amount of immersion of the oil pickup tube into oil to change.

[0007] In the situation that the speed of the motor is higher than a predetermined threshold speed, the actuator moves the oil pickup tube upwards and thus, provides the amount of immersion into oil to be decreased and hence the flow rate of the pumped oil to be decreased; and in the situation that the speed of the motor is lower than the threshold speed and in the period of time elapsing from the start of the motor until reaching the threshold speed, the actuator moves the oil pickup tube downwards and thus, provides the amount of immersion into oil to be increased and hence the flow rate of the pumped oil to be increased.

[0008] The actuator comprises an electromagnet which is activated by the speed control unit and thus, applies magnetic attraction force when the speed of the motor is lower than the threshold speed, and which is deactivated when the speed of motor is higher than the threshold speed, and a metal plate which is positioned on the upper side of the electromagnet. [0009] In an embodiment of the present invention, the magnetic attraction force applied by the electromagnet that is activated by the speed control unit stretches the carrier springs that support the motor inside the casing and thus, moves also the motor and the crankshaft, whereto the oil pickup tube is connected, downwards together with the metal plate and the oil pickup tube.

[0010] In another embodiment of the present invention, the oil pickup tube moves inside the crankshaft and independently of the crankshaft, and the oil pickup tube is connected to the crankshaft by helical springs. The upper end of the helical springs is connected to an upper flange extending to the inner wall of the crankshaft through the oil pickup tube, and the lower end of the helical springs is connected to a lower flange that is located at the lower end of the crankshaft and that surrounds the oil pickup tube with gaps. In this embodiment, the magnetic attraction force applied by the electromagnet overcomes merely the force of the helical springs and thus, moves the oil pickup tube downwards. The electromagnet consumes less energy in comparison with the previous embodiment wherein it pulls the motor and crankshaft group downwards together with the oil pickup tube.

[0011] In the hermetic compressor of the present invention, the speed control unit that adjusts the speed of the motor according to varying operating conditions also increases and decreases the amount of immersion of the oil pickup tube by means of the actuator, and an effective lubrication is realized by sending suitable amounts of oil to the crankshaft bearings under the operating conditions wherein the speed of the motor varies.

[0012] The hermetic compressor realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

[0013] Figure 1 - is the schematic view of a hermetic compressor.

[0014] Figure 2 - is the schematic view of a crankshaft and of an oil pickup tube that can move inside the crankshaft by means of the actuator.

[0015] The elements illustrated in the figures are numbered as follows:

1. Hermetic compressor

2. Casing

3. Motor 4. Crankshaft

5. Oil pickup tube

6. Carrier spring

7. Platform

8. Speed control unit

9. Actuator

10. Electromagnet

11. Metal plate

12. Helical spring

13. Upper flange

14. Lower flange

[0016] The hermetic compressor (1) comprises a casing (2) which carries the

components therein and wherein oil providing the movable components to be lubricated is placed, a motor (3) which has a rotor (R) and a stator (S), a piston which provides the refrigerant fluid to be sent to the refrigeration system in a pressurized state, a cylinder wherein the piston operates, a crankshaft (4) which is press-fittingly assembled to the core of the rotor (R) in its rotational axis direction and which provides the rotational movement of the rotor (R) to be transmitted to the piston, an oil pickup tube (5) which is connected to the crankshaft (4) and the lower end of which is immersed into oil inside the casing (2), and which sucks and delivers the oil to the crankshaft (4), more than one carrier spring (6) which are fixed to the lower side inside the casing (2) and which carry the motor (3), a platform (7) which is fixed to the lower side inside the casing (2) and which bears the oil pickup tube (5) lower end, through which the oil pickup tube (5) sucks the oil, by means of a hole situated at its center, and a speed control unit (8) which provides the speed of the motor (3) (number of revolutions of the rotor (R)) to be changed according to varying operating conditions.

[0017] The hermetic compressor (1) of the present invention comprises an

actuator (9) which is controlled by the speed control unit (8) and which provides the amount of immersion (D) into oil to be decreased by moving the oil pickup tube (5) upwards when the speed of the motor (3) is higher than a predetermined threshold speed (Vthreshold). and which provides the amount of immersion (D) into oil to be increased by moving the oil pickup tube (5) downwards when the speed of the motor (3) is lower than the threshold speed (Vthreshold) and iⁿ the period of time elapsing from the moment of start of the motor (3) until reaching the threshold speed (V threshold) (Figure 1 , 2).

The hermetic compressor (1) is of variable capacity type and by the speed control unit (8) the motor (3) is operated at low speed under light operating conditions wherein the need of refrigeration is low and at high speed under heavy operating conditions wherein the need of refrigeration is high. The operation of the motor (3) is realized within successive periods of stopping and operation, and the motor (3) operates at low speed from the moment of start until reaching the threshold speed (Vthreshold)- When the motor (3) is operated below the threshold speed (Vthreshold). the actuator (9) moves the oil pickup tube (5) downwards and thus, provides the amount of immersion (D) into oil to be increased and the flow rate of the oil sucked by the oil pickup tube (5) to be increased in proportion to the increased amount of immersion (D). Thus, when the motor (3) is operated at low speed, the desired amount of oil is delivered to the crankshaft (4) bearings. The centrifugal force that acts on the oil as a result of the rotation of the oil pickup tube (5) connected to the crankshaft (4) is utilized for transmitting the oil at the base of the casing (2) to the crankshaft (4) bearings. The centrifugal force acting on the oil as a result of the rotation of the oil pickup tube (5) causes the oil surface to have a parabolic shape inside the oil pickup tube (5). In the situation that the amount of immersion (D) of the oil pickup tube (5) is increased, the parabolic surface formed by the oil inside the oil pickup tube (5) is transmitted upwards as much as the increased amount of immersion (D) and provides the flow rate of the pumped oil to be increased. When the motor (3) is operated above the threshold speed (Vthreshold). the actuator (9) moves the oil pickup tube (5) upwards and thus, provides the amount of immersion (D) into oil to be decreased and the flow rate of the oil sucked by the oil pickup tube (5) to be decreased in proportion to the decreased amount of immersion (D). Thus, when the motor (3) is operated at high speed, the friction of the oil pickup tube (5) to the oil and hence the noise is decreased and

furthermore, the oil level inside the casing (2) is prevented from

decreasing.

[0019] The actuator (9) comprises an electromagnet (10) which is mounted onto the platform (7) and which forms a magnetic field by being activated by the speed control unit (8) when the speed of the motor (3) is lower than the threshold speed (Vthreshold). and which is deactivated by the speed control unit (8) when the speed of the motor (3) is higher than the threshold speed (Vthreshold). and a metal plate (11) which is positioned on the upper side of the electromagnet (10) by being mounted to the oil pickup tube (5) such that a distance between the metal plate (11) and the electromagnet (10) is calculated according to the change in the amount of immersion (D) of the oil pickup tube (5).

[0020] When the speed of the motor (3) drops below the threshold speed (V

threshold), the electromagnet (10) is activated by the speed control unit (8). By means of the generated magnetic field, the electromagnet (10) pulls the metal plate (11) at the upper side and thus, moves the oil pickup tube (5), to which the metal plate (11) is connected, downwards in the vertical direction and provides the amount of immersion (D) to be increased. When the speed of the motor (3) rises above the threshold speed (Vthreshold). the electromagnet (10) is deactivated by the speed control unit (8) this time, and the metal plate (11) is released and moves upwards by the effect of the carrier springs (6). The oil pickup tube (5) also moves upwards together with the metal plate (11) and thus, the amount of immersion (D) of the oil pickup tube (5) is decreased.

[0021] In an embodiment of the present invention, the magnetic attraction force applied by the electromagnet (10) that is activated by the speed control unit (8) stretches the carrier springs (6) and thus, moves also the motor (3) and the crankshaft (4), whereto the oil pickup tube (5) is connected, downwards together with the metal plate (11) and the oil pickup tube (5).

[0022] In another embodiment of the present invention, the hermetic compressor (1) comprises an oil pickup tube (5) which moves inside the crankshaft (4) in the vertical direction and independently of the crankshaft (4), and one or more helical springs (12) which are located between the oil pickup tube (5) and the crankshaft (4), which carry the oil pickup tube (5) inside the crankshaft (4) and which control the movement of the oil pickup tube (5) in the vertical direction (Figure 2).

[0023] The hermetic compressor (1), furthermore, comprises an upper flange (13) which is located at the oil pickup tube (5) upper end inside the crankshaft (4), which provides the oil pickup tube (5) to perform a sliding movement on the inner wall of the crankshaft (4), and to which the upper end of the helical spring (12) is connected, and a lower flange (14) which is located at the lower end of the crankshaft (4) and which surrounds the oil pickup tube (5) with gaps such that it will be able to move inside the crankshaft (4), and to which the lower end of the helical spring (12) is connected (Figure 2).

[0024] In this embodiment, in order to increase the amount of immersion (D) of the oil pickup tube (5), the oil pickup tube (5), which encounters the magnetic attraction force applied to the metal plate (11) by the

electromagnet (10) that is activated by the speed control unit (8), moves downwards inside the crankshaft (4) by shortening the helical springs (12), onto which the oil pickup tube (5) is seated. When the amount of immersion (D) of the oil pickup tube (5) is desired to be decreased, the electromagnet (10) is deactivated and thus, the pressure on the oil pickup tube (5) is removed and the oil pickup tube (5) carried by the helical springs (12) that extend by being released moves upwards inside the crankshaft (4). In this embodiment, in order to change the amount of immersion (D) of the oil pickup tube (5), only the metal plate (11) and the oil pickup tube (5) are moved by the electromagnet (10) and less energy is consumed in comparison with the previous embodiment.

[0025] In the hermetic compressor (1) of the present invention, the speed control unit (8) that adjusts the speed of the motor (3) according to varying operating conditions also increases and decreases the amount of immersion (D) of the oil pickup tube (5) by means of the actuator (9), and since the flow rate of the pumped oil is proportional to the amount of immersion (D) of the oil pickup tube (5), an effective lubrication is realized by sending suitable amounts of oil to the crankshaft (4) bearings under the operating conditions wherein the speed of the motor (3) is high and low. It is to be understood that the present invention is not limited by the embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection postulated by the claims of the present invention.

Claims

1. A hermetic compressor (1) comprising a casing (2) which carries the

components therein and wherein oil providing the movable components to be lubricated is placed, a motor (3), a crankshaft (4), an oil pickup tube (5) which is connected to the crankshaft (4) and the lower end of which is immersed into oil inside the casing (2), and which sucks and delivers the oil to the crankshaft (4), more than one carrier spring (6) which are fixed to the lower side inside the casing (2) and which carry the motor (3), a platform (7) which is fixed to the lower side inside the casing (2) and which bears the oil pickup tube (5) lower end, through which the oil pickup tube (5) sucks the oil, by means of a hole situated at its center, and a speed control unit (8) which provides the speed of the motor (3) to be changed according to varying operating conditions,

characterized by an actuator (9) which is controlled by the speed control unit (8) and which provides the amount of immersion (D) into oil to be decreased by moving the oil pickup tube (5) upwards when the speed of the motor (3) is higher than a predetermined threshold speed (Vthreshold). and which provides the amount of immersion (D) into oil to be increased by moving the oil pickup tube (5) downwards when the speed of the motor (3) is lower than the threshold speed (V_threshold)-

2. A hermetic compressor (1) as in Claim 1 , characterized by the actuator (9) comprising an electromagnet (10) which is mounted onto the platform (7), and a metal plate (11) which is mounted to the oil pickup tube (5) such that a distance between the electromagnet (10) and the metal plate (11) is calculated according to the change in the amount of immersion (D) of the oil pickup tube (5).

3. A hermetic compressor (1) as in Claim 2, characterized by the actuator (9) comprising an electromagnet (10) which is activated by the speed control unit (8) and which stretches the carrier springs (6) by the magnetic attraction force it applies and thus, which moves the motor (3) and the crankshaft (4), whereto the oil pickup tube (5) is connected, downwards together with the metal plate (11) and the oil pickup tube (5).

4. A hermetic compressor (1) as in Claim 1 or 2, characterized by the oil pickup tube (5) which moves inside the crankshaft (4) in the vertical direction and independently of the crankshaft (4), and by one or more helical springs (12) which are located between the oil pickup tube (5) and the crankshaft (4), which carry the oil pickup tube (5) inside the crankshaft (4) and which control the movement of the oil pickup tube (5) in the vertical direction.

5. A hermetic compressor (1) as in Claim 4, characterized by an upper flange (13) which is located at the oil pickup tube (5) upper end inside the crankshaft (4), which provides the oil pickup tube (5) to perform a sliding movement on the inner wall of the crankshaft (4), and to which the upper end of the helical spring (12) is connected, and a lower flange (14) which is located at the lower end of the crankshaft (4) and which surrounds the oil pickup tube (5) with gaps such that it will be able to move inside the crankshaft (4), and to which the lower end of the helical spring (12) is connected.