Temperature supervising arrangement for a cabinet or the like

Abstract

 Arrangement for supervising the temperature in a cabinet (10) including a temperature sensor (23) being constructed to activate an alarm device (26) at a previously determined temperature. The temperature sensor is arranged in connection to the separating plane between the cabinet (11) and a door closing the cabinet so that it will be influenced by the air surrounding the sensor.

Description

[0001] The present invention relates to an arrangement for supervising the tempera­ture in a cabinet or the like according to the preamable of the following claim 1.

[0002] When supervising the temperature in a compartment closed by a door, a sensor is often placed inside the compartment in a position where it senses the air temperature. In certain embodiments as a freezer the sensor is instead placed so that it senses the temperature of a shelf and then imitates the temperature of the objects stored on the shelf.

[0003] Freezer thermometers are usually meant for indicating the temperature of the freezer goods. In order to avoid change of the temperature valuie when the door is opened the shown value can constitute the average value of many measure values collected during a certain period. If now one wishes to provide the cabinet with an alarm device giving a warning when the door unintentionally has been left open or has for some reason opened itself, it lies near at hand to utilize the temperature value shown. As the temperature must nomally deviate substantially from the normal level, e.g. 10 degrees, and the average value shown is changed very slowly, this has the effect that the alarm is not activated until a long time has elapsed. By that, a risk will arise that the goods will deteriorate in quality and might even be destroyed.

[0004] The purpose of the invention as applied to a device for supervising the temperature in a cabinet according to the premable of claim 1 is to ensure acitivation of the alarm device a short predetermined time after the door has been opened. In that way, for example in freezers, damages on the goods caused by the rise in the temperature can be reduced or at best be avoided. Preferably, for the short time a few minutes should be chosen so that a normal opening of the door in connection with putting in or taking out goods will not activate the alarm device.

[0005] The object is achieved in a device showing the characteristics indicated in claim 1. Preferred embodiments are indicated in the sub-claims. An embodiment of the invention will now be described with reference to the accompanying drawing in which Fig. 1 shows a front view of a freezer cabinet and Fig. 2 shows a cross section through the cabinet seen from the side and with the door slightly open. The cross section is situated along the line II - II in Fig. 1.

[0006] The drawing shows a freezer 10 of a customary design. The cabinet comprises a cabinet part II closed by a door 12. The door can be operated by means of a handle 13. In the cabinet frozen foods can be stored on shelves 14, 15, 16. The door consists of an interior wall 17 and an outer wall 18, separated by an insulating layer 19. Recesses 20, 21 on the interior and on the outer wall, respectively, situated just opposite each other, are utilized when fitting a holder 22 for a temperature sensor 23, constructed as a thermister, as well as for a unit 24 containing a temperature indicator device in the shape of a digital display 25 combined with a temperature supervising device. The unit 24 thereby constitutes a control device for the temperature as well as for the alarm indication. In respect of the alarm indication a warning light 26 is used. The holder 22 and the unit 24 are separated by the insulating layer 19 except for a little space where a thin channel 27 is made in the insulating layer through which the temperature indi­cator 23 is, by means of two wires 28, 29, connected to the unit 24. The holder 22 and the unit 24 are fixed in the respective recess by means of snap-in closures, not shown. The holder is constructed such that the temperature indicator will be situated at some distance from the interior wall of the door and so that it can be influenced by the ambient air.

[0007] The unit 24, which especially includes a microprocessor, is constructed so that it through an average value formation of a number of instantaneous, measured air temperature values imitates the temperature of the freezing goods. This temperature is normally shown by the digital display 25 and changes in the air temperature only slowly influcence on the shown values, e.g. by one degree every 17th minute. This involves that the temperature value shown will not be capable of activating the temperature alarm. Instead, the momentarily measured values are utilized for this purpose. Therefore, the alarm can be activated as soon as the previously determined short time has elapsed and the microprocessor has confirmed that the values momentarily measured at still unacceptably high.

[0008] In known freezers with the temperature sensor situated inside the cabinet it might take a very long time until an unsatisfactorily closed door will be discovered leading to an alarm. In the embodiment according to the invention the temperature sensor is situated in the separating plane between the door and the cabinet and if the door is slightly opened, warm air will immediately through chimney effect rise upwards in the door gap formed. The warm air will immediately influence on the temperature sensor, which inputs increased temperature values to the unit 24 and the latter activates the warning light 26 after the previously determined short time.

[0009] In a known freezer a temperature indication device is arranged in the cabinet and visible from the outside through an opening in the door having the cor­responding size. In the opening there is no insulation and a certain heat leakage has to be anticipated.

[0010] Regarding the described embodiment any heat leakage has been avoided through the fact that only a thin channel connects the holder 22 with the unit 24 allowing the insulation to go into the space between the holder and the unit so that it surrounds the channel.

Claims

1. Arrangement for supervising the temperature in a cabinet (10) or the like including a temperature sensor (23) being arranged to activate an alarm device (26) at a previously determined temperature characterized in that the temperature sensor (23) is disposed close to the separating plane between the cabinet (10) and a door (12) closing the cabinet so that it will be influenced by the air surrounding the sensor (23).

2. Arrangement according to claim 1, characterized in that the temperature sensor (23) is aranged on the door (12).

3. Arrangement according to claim 2, characterized in that the temperature sensor (23) is arranged on the upper part of the door.

4. Arrangement according to claim 3, characterized in that the cabinet (10) is a freezer cabinet provided with a temperature indicator device (25) indicating the temperature of the freezing goods stored in the cabinet, a control device being arranged to convert through an average value formation, temperature values momentarily measured by the temperature sensor (23) to establish the freezing goods temperature shown by the indicator device, and the control device (24) being arranged to activate the alarm device (26) at the previously determined temperature.

5. Arrangement according to claim 4, characterized in that the previously determined temperature consists of a momentarily measured tempera­ture value.

6. Arrangement according to claim 4 or 5, characterized in that it forms a unit (24) with the temperature indicator device, which unit is arranged in a recess (23) of the door (12).

7. Arrangement according to claim 6, characterized in that the door (12) comprises an outer wall (18) and an inner wall (17) which are separated by an insulating layer (19) and have recesses (21, 20) situated mainly opposite each other said unit (24), formed by the temperature supervising device and the temperature indicating device, respectively, being fitted in the recess (21) of the outer wall (18), while the other recess (20) constitutes a fixing for a holder (22) carrying the temperature sensor (23) in a position at some distance from the door (12), said unit (24) and the holder (22) then being separated by the insulation layer (19) of the door and the temperature sensor (23) being connected to the unit (24) via a thin channel (27) made in the insulation layer.

Drawing