WO2008119808A1

WO2008119808A1 - A cooling device

Info

Publication number: WO2008119808A1
Application number: PCT/EP2008/053898
Authority: WO
Inventors: Bekir Ozyurt; Ozgur Bilgic; Yalcin Guldali
Original assignee: Arcelik Anonim Sirketi
Priority date: 2007-04-02
Filing date: 2008-04-02
Publication date: 2008-10-09

Abstract

The present invention relates to a cooling device (1) wherein the flow rate in the capillary tube (5) is regulated by changing the distance between the coils thereof and thereby increasing the refrigeration performance.

Description

PatXML 1/9 BB1057-7.597

Description

A COOLING DEVICE

[0001] The present invention relates to a cooling device that comprises a refrigeration circuit.

[0002] In the refrigeration circuits of cooling devices like the refrigerator and air conditioner, capillary tubes having an inner diameter and length suitable to system requirements are used for decreasing the pressure in order to bring the refrigerant to the desired pressure value. The capillary tubes can provide constant pressure decrease (ΔP) in constant inlet conditions, that is, function at a constant flow rate. However, this brings about fluctuations in the system performance when there are variations in the ambient temperature. Moreover, in particularly cyclic refrigerant circuits, the required refrigerant flow rate is different in each of the cyclic periods for the best performance. In the event that capillary tubes are used that provide constant flow rate again, it is inevitable for the refrigerant circuit not to function with low performance from time to time.

[0003] Various implementations are developed in the state for solving these problems. For example in the refrigerating system explained in the Great Britain patent no GB605860, a capillary device is located in an entrance chamber contacting partially with the refrigerant liquid and partially with the refrigerant vapor. The rate of flow in the capillary tube is changed by controlling the liquid-gas balance in the entrance chamber.

[0004] In other state of the art applications as that of the United States of America patent no US3884663 and European patent no EP1726892, more than one capillary tube having different flow path resistance are connected to the refrigerant cycle in parallel in order to adjust the system performance. An electro-mechanic trigger means controls directing the refrigerant circulation into each capillary tube.

[0005] Another state of the art application is explained in the United States of America patent no US2703965. In this embodiment, the flow of cooling liquid through the condenser is regulated in response to the change in superheat in the evaporator exit thereby regulating the flow of the cooling liquid in the capillary tube. PatXML 2/9 BB1057-7.597

[0006] The aim of the present invention is the realization a cooling device wherein the cooling performance is increased by changing the flow rate in the capillary tube.

[0007] The refrigeration circuit used in the cooling device of the present invention comprises a compressor, an evaporator that absorbs the ambient thermal energy in the environment to be cooled, a condenser that transfers the thermal energy to the outside and a helical capillary tube that maintains the refrigerant leaving the condenser to expand and to be delivered to the evaporator.

[0008] The cooling device furthermore comprises a movement mechanism, which when operated, changes the distance between the coils of the capillary tube thus changing the flow resistance of the capillary tube and a control unit that actuates the movement mechanism in the increasing or decreasing direction when the requirement to increase or decrease the capillary tube flow resistance is detected.

[0009] In an embodiment of the present invention, the various operating steps wherein changing the flow resistance of the capillary tube is required are recorded in the control unit. For example, how much and in what direction the flow resistance of the capillary tube will be changed at the initial start-up of the compressor, just before and just after the compressor stops and starts is recorded. In this event, the control unit sends a command to the movement mechanism for changing the capillary tube flow resistance in accordance with these recorded steps.

[0010] In another embodiment of the present invention, the various parameter intervals for changing the flow resistance of the capillary tube, for example the values of capillary tube flow resistance for different ambient temperature values are recorded in the control unit. In this event, the control unit delivers command to the movement mechanism for changing the flow resistance depending on the ambient temperature values determined by measurements.

[0011] The movement mechanism can be a hydraulic or a pneumatic cylinder or a servomotor.

[0012] In an embodiment of the present invention, the movement mechanism PatXML 3/9 BB1057-7.597

comprises a cylinder with a pneumatic piston and a valve. In this embodiment, one end of the capillary tube is secured to the cooling device and the other end to the piston and in the free position and a starting distance of (H₁) is provided between two successive coils. A push and a pull air inlet are provided on the cylinder, one at the front and one at the rear of the piston. A pipe delivering air to the cylinder and a tri-directional valve on this pipe are provided. The valve takes the position of delivering air towards the pull inlet according to the data received from the control unit when moving in the direction for widening the coil distances of the capillary tube is wanted, that is, decreasing the flow resistance. In this position, the piston moves forwards as a result of the force exerted on the piston by the air that fills the rear half of the cylinder, and pulls along together the capillary tube connected thereto. Thus, the distance (H₂) between the coils increases and the flow resistance of the capillary tube decreases.

[0013] On the other hand, when the coil distances of the capillary tube is wanted to be narrow, that is, moving to increase the flow resistance in accordance with data received from the control unit, the valve takes the position for delivering air to the pull inlet. In this case, the piston recedes as a result of the force exerted on the piston by the air that fills the front half of the cylinder, and pushes together the capillary tube connected to the piston. Thus the distance (H₃) between the coils decreases and the flow resistance of the capillary tube increases.

[0014] In an embodiment of the present invention, the control unit sends a command to the movement mechanism for increasing the distance between the coils of the capillary tube during the initial start-up of the compressor. Thus, after the initial start-up of the compressor, in the time period required for the entire refrigerant in the condenser tubes to change to liquid phase, the created flow rate drop of the refrigerant in the liquid gas mixture is counterbalanced by decreasing the flow resistance of the capillary tube.

[0015] In another embodiment of the present invention, the control unit sends a command to the movement mechanism for decreasing the distance PatXML 4/9 BB1057-7.597

between the coils of the capillary tube after the compressor stops. Thus, the flow resistance of the capillary tube is increased and the natural refrigerant migration that occurs from the condenser to the evaporator after the compressor stops due to pressure difference and the high temperature refrigerant collecting in the evaporator resulting to create thermal load is minimized.

[0016] The cooling device designed to fulfill the object of the present invention is illustrated in the attached figures, where:

[0017] Figure 1 - is the perspective view of a cooling device.

[0018] Figure 2 - is the schematic view of a refrigeration circuit.

[0019] Figure 3 - is the schematic view of the capillary tube in the initial position used in an embodiment of the present invention.

[0020] Figure 4 - is the schematic view of the capillary tube in the coil distance increased position used in an embodiment of the present invention.

[0021] Figure 5 - is the schematic view of the capillary tube in the coil distance decreased position used in an embodiment of the present invention.

[0022] Figure 6 - is the schematic view of the movement mechanism and the capillary tube used in an embodiment of the present invention.

[0023] The elements illustrated in the figures are numbered as follows:

1. Cooling device

2. Compressor

3. Evaporator

4. Condenser

5. Capillary tube

6. Control unit

7. Movement mechanism

8. Cylinder

9. Piston

10. Pipe

11. Valve

12. Push inlet

13. Pull inlet

[0024] The cooling devices (1) comprise a compressor (2), an evaporator (3) that PatXML 5/9 BB1057-7.597

absorbs the thermal energy in the cooled environment, a condenser (4) that transfers the thermal energy outside and a helical shaped capillary tube (5) that maintains the refrigerant leaving the condenser (4) to expand and to be delivered to the evaporator (3) (Figure 1 and Figure 2).

[0025] The cooling device (1) of the present invention comprises a movement mechanism (7) that changes the distance between the coils of the capillary tube (5) when actuated and a control unit (6) that controls the operation of the movement mechanism (7).

[0026] In the preferred embodiment of the present invention, the capillary tube (5) is secured from one end to a point in the cooling device (1) and the free end is fastened to the movement mechanism (7). The free end is pulled to increase or is pushed to decrease the distance between the coils by the movement mechanism (7) according to the command received from the control unit (6).

[0027] In an embodiment of the present invention, the conditions when the flow resistance of the capillary tube (5) is required to be changed at the initial start-up or stop of the compressor (2) during the operation of the cooling device (1) and the desired amount of change in these conditions are recorded in the control unit (6). When a recorded condition is encountered, for example when the compressor (2) starts to operate, the control unit (6) sends a command to the movement mechanism (7) for changing the coil distance of the capillary tube (5) to the recorded value. The movement mechanism (7) pulls or pushes the capillary tube (5) from the free end for changing the coil distance of the capillary tube (5) to the desired value in response to the said command.

[0028] In another embodiment of the present invention, the outside environment parameters such as temperature, humidity etc. and the desired change amounts for the different values of these parameters for which the flow resistance of the capillary tube (5) needs to be changed are recorded in the control unit (6). Similarly, the control unit (6) sends a command to the movement mechanism (7) depending on the changes in these parameters to maintain the change in the coil distance of the capillary tube (5).

[0029] During the start-up of the compressor (2), the change of the entire PatXML 6/9 BB1057-7.597

refrigerant in the condenser (4) tubes to the liquid phase takes a certain time. In this duration, the refrigerant being in the liquid gas mixture state results in the flow rate to fall. This is an unwanted condition for the efficient performance of the cooling device (1). In an embodiment of the present invention, in order to counterbalance the said flow rate fall, the control unit (6) sends a command to the movement mechanism (7) during the start-up of the compressor (2) for increasing the distance between the coils of the capillary tube (5). Consequently, after the initial start-up of the compressor (2), the flow resistance of the capillary tube (5) is decreased and the sufficient amount of refrigerant is fed to the evaporator (3).

[0030] After the stop of the compressor (2), another unwanted condition is the natural refrigerant migration from the condenser (4) to the evaporator (3) due to the difference of pressure. In another embodiment of the present invention, in order to minimize this problem, a command is sent to the movement mechanism (7) just after the compressor (2) stops for decreasing the distance between the coils of the capillary tube (5). Thus, the flow resistance of the capillary tube (5) is increased and the thermal load resulting from the filtering of the hot refrigerant into the evaporator (3) is prevented.

[0031] In an embodiment of the present invention, the movement mechanism (7) comprises a cylinder (8), a piston (9) that moves inside the cylinder (8) by the effect of the force applied thereon, a push and a pull inlet (12, 13) situated at each end of the cylinder (8) allowing entry/exit of air into the cylinder (8), at least one pipe (10) for transfer of air to these inlets (12, 13) and at least one valve (11) that regulates the amount and direction of air flow in the pipe (10). In this embodiment, one end of the capillary tube (5) is fastened to the cooling device (1) and the other end to the piston (9). The end of the capillary tube (5) fastened to the piston (9) moves with respect to the motion of the piston (9) inside the cylinder (8) and the distance (H) between the successive coils is regulated. (Figure 6)

[0032] In this embodiment, an initial distance (H₁) is provided between the successive coils of the capillary tube (5). When the decision for widening the coil distance of the capillary tube (5) is given according to the data PatXML 7/9 BB1057-7.597

received from the control unit (6), a command to this end is sent to the movement mechanism (7). The movement mechanism (7) brings the valve (11) to the position for delivering air towards the pull inlet (13) in response to this command received from the control unit (6). Thus, air fills in the front half of the cylinder (8). As a result of the force exerted by air on the piston (9), the piston (9) moves forward and pulls along the capillary tube (5) connected to the piston (9). Thus, the distance (H₂) between the coils increases and the flow resistance of the capillary tube decreases. (Figure 3 and Figure 4)

[0033] Similarly, when the decision for narrowing the coil distance of the capillary tube (5) is given according to the data received from the control unit (6), a command to this end is sent to the movement mechanism (7). The movement mechanism (7) brings the valve (11) to the position for delivering air towards the push inlet (12) in response to this command received from the control unit (6). Thus air fills in the rear half of the cylinder (8). As a result of the force exerted by air on the piston (9), the piston (9) moves forward and pulls along the capillary tube (5) connected to the piston (9). Thus the distance (H₃) between the coils decreases and the flow resistance of the capillary tube (5) increases (Figure 3 and Figure 5).

[0034] In the cooling device (1) of the present invention, changing the distance between the successive coils of the capillary tube (5) and thus the flow resistance with the assistance of the movement mechanism (7) provides to regulate the refrigeration capacity sensitively, preventing the lowering of the cooling performance due to changes in the ambient temperature.

Claims

PatXML 8/9 BB1057-7.597Claims

1. A cooling device (1 ) that comprises a compressor (2) maintaining the refrigeration cycle, an evaporator (3) that absorbs the thermal energy in the cooled environment, a condenser (4) that transfers the thermal energy outside and a helical capillary tube (5) that maintains the refrigerant leaving the condenser (4) to expand and to be delivered to the evaporator (3) and characterized by a movement mechanism (7) that changes the distance between the coils of the capillary tube (5) when operated.

2. A cooling device (1) as in Claim 1 , characterized by a control unit (6) that controls the operation of the movement mechanism (7).

3. A cooling device (1) as in any one of the above claims, characterized by a control unit (6) that sends a command to the movement mechanism (7) according to the outside environment parameters such as temperature, humidity etc.

4. A cooling device (1) as in any one of the above claims, characterized by a capillary tube (5) that is secured from one end to a point in the cooling device (1) and the free end fastened to the movement mechanism (7) and a movement mechanism (7) that pulls the free end to increase or pushes to decrease the distance between the coils according to the command received from the control unit (6).

5. A cooling device (1) as in any one of the above claims, characterized by a control unit (6) that sends a command to the movement mechanism (7) for increasing the distance between the coils of the capillary tube (5) during the start-up of the compressor (2).

6. A cooling device (1) as in any one of the above claims, characterized by a control unit (6) that sends a command to the movement mechanism (7) for decreasing the distance between the coils of the capillary tube (5) just after the compressor (2) stops.

7. A cooling device (1) as in any one of the above claims, characterized by a movement mechanism (7) that comprises a cylinder (8), a piston (9) that moves inside the cylinder (8) by the effect of the force applied thereon, a push and a pull inlet (12, 13) situated at each end of the cylinder (8) allowing entry/exit of air into the cylinder (8), at least one pipe (10) for transfer of air to PatXML 9/9 BB1057-7.597

these inlets (12, 13) and at least one valve (11) that regulates the amount and direction of air flow in the pipe (10).