DK159893B - COOLING DEVICE - Google Patents

Description

in

DK 159893B

The present invention relates to a cooling device of the type set out in the preamble of claim 1.

Such a device has the advantage that it is inexpensive to manufacture in that only one compressor is required for the operation of both the cooling chamber and the freezing chamber.

In a known device of this kind, the means sensing the temperature of the refrigeration evaporator is placed in direct thermal contact 10 with the refrigeration evaporator. Said means is arranged to act on the valve means so that the circulation of refrigerant through the refrigerant evaporator is interrupted when one reaches below a certain lower temperature of the refrigerant evaporator, and to resume the circulation when one reaches above a certain higher temperature. The higher temperature is usually approx. + 3 ° C for the evaporator to be defrosted and the lower temperature is so low, e.g. -20 * 0 that a sufficient cooling effect is obtained on the goods in the cooling chamber.

20 When hot items are placed in the freezer chamber for freezing, the heat load on the freezer evaporator will increase. As a result, the evaporation temperature in the freezer evaporator rises, which in turn means that the evaporation temperature in the refrigerated evaporator associated with the freezer evaporator also rises, which means that during the freezing period, which can be relatively long, it will take a relatively long time. before the refrigerant evaporator reaches its lower temperature and is switched off by the refrigerant circuit. As a result, the cooling effect in the cooling chamber becomes so great during the freezing period that the goods, e.g. milk, in the cold room freezes, which is obviously a disadvantage.

This disadvantage is avoided in the device according to the invention in that the initially mentioned device according to the invention is characterized by what is stated in the characterizing part of claim 1.

2

DK 159893B

In this way it becomes possible to prevent the refrigerated evaporator from operating during freezing of goods in the freezing chamber for such a long time that the goods in the refrigerating chamber freeze, and at the same time the device maintains its function to automatically defrost the refrigerated evaporator.

GB Patent Specification No. 2,123,992, which describes a refrigeration unit of the type indicated in the introduction, shows another solution for preventing too low temperatures from occurring in the refrigeration chamber.

However, this solution is obtained by means of an additional sensor which senses the temperature of the atmospheric air in the cooling chamber. With the present cooling device, one has become free of such an additional sensor, which makes the cooling device according to the invention much simpler.

15

It is known per se to arrange temperature sensing means partially thermally insulated from an element to be sensed, thereby moderating the direct influence of the element on the sensing means. U.S. Patent No. 3,026,688 discloses e.g. a refrigerator in which overcooling of a freezer is prevented by actuating a fan which is regulated by means of a means which senses the temperature of the inner wall of the freezer chamber. The refrigerator's compressor is regulated by means of a device that senses the temperature of an evaporator in a refrigeration chamber. Both of the said means are arranged partially thermally insulated in relation to the wall or the evaporator. These insulations, for which the reason for their presence is not explained in detail, seem to indicate regulatory precautions to make the refrigerator work properly.

30

An exemplary embodiment of a device according to the invention is described below with reference to the drawing, in which fig. 1 shows a refrigerant circuit with a refrigerant evaporator in a refrigeration chamber, a freezer evaporator in a freezing chamber, a compressor for driving the refrigerant through the circuit and an adjustable valve which directs the refrigerant through both elements, 3

DK 159893 B

fig. 2 shows the valve adjusted so that the cooling element is switched off from the circuit, fig. 3 shows how two different temperatures in the cooling chamber vary with time under normal load in the freezing chamber, and fig. 4 shows how the mentioned temperatures vary when the freezing takes place in the freezing chamber.

In FIG. 1 shows a refrigeration unit having a refrigeration chamber 12 which must be able to hold goods at a temperature of approx. + 4eC, and a freezing chamber 14, which must be able to hold goods at a temperature of approx. -18 ° C. The cooling chamber 12 is cooled by a cooling evaporator 16 and the freezing chamber 14 is cooled by a freezing evaporator 18.

The refrigeration evaporator 16 is part of a circulating circuit for a refrigerant consisting of a compressor 20, a condenser 21, a valve 22, a throttle in the form of a capillary tube 24, the refrigeration evaporator 16 and the freezer evaporator 18.

20

The freezer evaporator 18 can also be switched on in a refrigerant circulation circuit consisting of the compressor 20, the condenser 21, the valve 22, see fig. 2, a throttle in the form of a capillary tube 25 and the freezer evaporator 18.

25

The temperature in the freezing chamber is monitored by a means 26 which at a given higher temperature, e.g. -15 ° C, gives a signal to the compressor 20 to start, and at a given lower temperature, e.g. -23 ° C gives a signal that the compressor must stop 30.

In the cooling chamber 12, the temperature is monitored by a means 28 which is in thermal contact with the cooling evaporator 16 via a heat insulating plate 30. When the means 28 senses a given higher temperature, e.g. + 3eC, the means 28 signals the valve 22 to position itself in the position shown in fig. 1 so that refrigerant can circulate through the cooling element 16. When the means 28

DK 159893 B

4 then senses a given lower temperature, e.g. -15eC, the means 28 signals the valve 22 to position itself in the position shown in fig. 2, whereby the refrigerant flow through the cooling element 16 ceases.

In FIG. 3 and 4 show examples of the effect of the insulation 30 on the temperature T in the cooling chamber as a function of the time t. The compressor 20 is assumed to be running throughout the circuit shown in fig. 3 and 4.

In FIG. 3 shows the temperature profile in the cooling chamber during normal operation of the freezing chamber, ie. when there is no freezing in this. The solid curve 32 shows the temperature of the cooling element 16 and the punctured curve 34 shows the temperature 15 of the means 28. At time ΐχ the means 28 signals the valve 22 to carry refrigerant to the cooling evaporator 16. At time t2 the element 20 has a temperature of -20eC, while the member 28 lags behind in temperature due to the insulation 30 and has a higher temperature, -15eC.

At -15 ° C, the means 28 signals the valve 22 to close the refrigerant supply to the refrigerant evaporator 16. The goods in the refrigeration chamber having a temperature of approx. + 4 ° C, then the heat evaporator 16 and the body 28 heat up. At time t3 the heat evaporator reaches 160 ° C, whereby the defrosting of the element begins.

At time t4, the refrigerant evaporator 16 is defrosted and the process beginning at ti is repeated.

In FIG. 4 shows the corresponding temperature profile in the cooling chamber when freezing goods in the freezing chamber.

30

At time ts, refrigerant is released through the evaporator 16. Due to the large heat load on the freezer evaporator 18, the temperature in the evaporator 16 rises and it takes longer before the member 28 reaches the lower temperature, -15 ° C, at which the member 28 signals that interrupt the refrigerant circulation through the refrigerant evaporator 16. With the slow temperature change, the temperatures of the refrigerant evaporator 16 and

Claims (2)

Without the insulation 30, i.e. when the prior art means 28 is in direct thermal contact with the refrigerant evaporator 16, the temperature of the refrigerant evaporator 16 would continue to fall along the dotted line 3. Only at time ίγ would the means 28 initiate interruption of the refrigerant supply 10 to the refrigerant evaporator 16. But at the time The evaporator has taken so much heat from the goods in the cold chamber that it has been frozen, which can be prevented by the insulation 30 according to the present invention. In order to obtain a necessary cooling effect and simultaneous defrosting in the cooling chamber 12, both in the prior art and in the refrigeration evaporator according to the invention the temperature of the refrigeration evaporator 16 during normal operation of the freezing chamber must be raised to substantially the same lowest temperature, -20 ° C in the above 20 mentioned example. In the prior art this is produced by a temperature sensing means which switches at -20 ° C and by the invention with a temperature sensing means 28 which switches already at -15 ° C. By arranging the insulation 30 and adjusting the wrapping point for the member 28 from -20 ° C to -15 ° C, one can with very simple means, i.e. the insulation 30 prevent the goods from freezing in the cold chamber when freezing takes place in the freezing chamber. 30 Patent claims. Cooling device with a cooling chamber (12) with a beer evaporator (16) and a freezing chamber (14) with a freezing evaporator (18), with a first refrigerant circuit (20, 21, 22, 24, 16, 18) * wherein the refrigerant medium sequentially flows through a compressor (20), the refrigeration evaporator (16) and the freezer evaporator (18), with another refrigerant medium circuit (20, 21, 22, 25, 18) in which the refrigerant flows through the compressor (20). 20), bypassing the refrigeration evaporator (16) and through the freezer evaporator (18), with a valve 1 device (22) for interrupting the first or the second refrigerant circuit, with a first element (28) which senses the refrigeration evaporator (16 ) temperature and operates the valve 1 device (22) for closing the first refrigerant circuit at a given higher first temperature and interrupting the first refrigerant circuit at a given lower second temperature, and with a second element (26) 10 sensing the temperature in the freezing chamber ( 14), and which is arranged to start the compressor (20) at a given higher third temperature and to stop the compressor at a given lower fourth temperature, characterized in that a heat-insulating layer (30) is arranged between the first element 15 (28) and the cooling evaporator (16), and that the first element (28) is designed as follows, that its switching point is at a given lower temperature set at a temperature value above the lowest temperature of the refrigerated evaporator reached in case of minimal freezer evaporator load. 20 Device according to Claim 1, characterized in that the layer is formed by a heat-insulating plate (30). 25 30 35