Installation for controlling the defrosting of a refrigerating means

Abstract

 The invention relates to an installation for controlling the defrosting of a refrigerating means, said installation being provided with a programmable defroster clock (1) by means of which the defrosting means for defrosting the refrigerating means can be put in action at regular intervals. There is also provided an additional defroster clock (6) which at set times delivers a pulse for putting the defrosting means in action. The activating of the defrosting means only takes place thereby when an ice detector (8) provided on the refrigerating means signals the presence of ice.

Description

[0001] The invention relates to an installation for controlling the defrosting of a refrigerating means, said installation being provided with a programmable defroster clock by means of which the defrosting means for defrosting the refrigerating means can be put in action at regular intervals.

[0002] During operation of refrigerating means, such as are used in for example refrigerated counters, freezing rooms etc., the evaporators become iced over. The extent of said icing over depends on a number of factors and is usually not constant in time, therefore. With the conventional devices, however, means are still activated at set times, by means of the programmable defroster clock, to defrost the icing on the evaporators or on a plurality of evaporators. With installations which must maintain a temperature above zero this may take place by switching off the refrigerating machine.

[0003] Another possibility is that filaments are provided on the refrigerating means, which filaments are heated when the refrigerating means are put in action in order to defrost the ice.

[0004] With some refrigerating systems it is also possible to reverse the flow in the refrigerating system, so that hot gas will flow through the refrigerating means instead of cold refrigerating medium.

[0005] In practice it may be desirable, however, to be able to put the defrosting means in action more in dependence on whether or not ice is present. The object of the invention is to obtain an installation of the above kind, which can be easily converted into an installation wherein the defrosting means only start to operate when a certain quantity of ice has been deposited on the cooling means.

[0006] According to the invention this objective can be accomplished in that an additional defroster clock is provided, which at set times delivers a pulse for activating the defrosting means, whereby the activating of the defrosting means by means of the defroster clock only takes place when an ice detector provided on the refrigerating means signals the presence of ice.

[0007] By using the construction according to the invention it is possible to have the additional defroster clock deliver a pulse at comparatively short time intervals, whereby the defrosting means will only be put in action, however, when a signal is received from the ice detector as well.

[0008] A favourable factor is thereby that in the event of a failure of the ice detector defrosting of the refrigerating means at set intervals will still be effected by means of the programmable defroster clock.

[0009] The invention will be further explained hereinafter with reference to the accompanying figure showing a diagram of the installation according to the invention.

[0010] The installation illustrated in the figure comprises a program­mable defroster clock 1, which is connected via an AND gate and a flipflop 3 to an OR gate 4, via which a signal can be supplied to defrosting means acting on a refrigerating means.

[0011] To the AND gate 2 there is furthermore connected, in a conventional manner, a thermostat 5, which can deliver a signal for ending the operation of the defrosting means. The use of such a defroster clock with thermostat is generally known. The programmable defroster clock 1 can thereby be set for activating the defrosting means at regular intervals.

[0012] According to the invention there is furthermore provided a defroster clock 6, which at regular intervals of e.g. one and a half hours delivers a pulse to a flipflop 7, which is likewise connected to the OR gate 4.

[0013] To the flipflop 7 there is furthermore connected an ice detector 8. Said ice detector may e.g. be designed as disclosed in the European patent EP-B-0135958.

[0014] The thermostat 5 is also connected to the flipflop 7, via an AND gate 10.

[0015] Besides being connected to the flipflop 7 the ice detector 8 is also connected to a comparator 9, which is connected between the ice detector 8 and the two defroster clocks 1 and 6, in the manner illustrates in the diagram.

[0016] By means of the comparator 9 it is effected that when the ice detector 8 is not connected to the comparator 9 the defrosting is controlled by means of the conventional programmable defroster clock 1, whilst in the case that the ice detector is connected the operation of the defrosting means will be controlled by means of the defroster clock 6.

[0017] As already mentioned before the defroster clock 6 will thereby deliver a pulse to the flipflop 7 at regular intervals. Only when the presence of ice on the refrigerating means is signalled to the flipflop 7 from the ice detector 8 as well will the means for defrosting be put in action via the flipflop 7 and the gate 4.

[0018] The various parts 1 - 4, 6, 7, 9 and 10 can be effectively incorporated in a unit and, dependent on whether or not an ice detector is provided on the refrigerating means and connected to the comparator 9, the defrosting means will be put in action by means of the normal programmable defroster clock 1 or by means of the defroster clock 6 in combination with the ice detector 8. In the event of a failure of the ice detector 8 the control of the activating of the defrosting means can be taken over by the defroster clock 1, so that a defrosting at set intervals can still be effected.

Claims

1. Installation for controlling the defrosting of a refri­gerating means, said installation being provided with a programmable defroster clock by means of which the defrosting means for defrosting the refrigerating means can be put in action at regular intervals, characterized in that an additional defroster clock is provided, which at set times delivers a pulse for activating the defrosting means, whereby the activating of the defrosting means by means of the defroster clock only takes place when an ice detector provided on the refrigerating means signals the presence of ice.

2. Installation according to claim 1, characterized in that a comparator is connected between the ice detector and the two defroster clocks, which comparator, dependent on whether or not the ice detector has been connected to the comparator, activates the programmable defroster clock or the defroster clock interacting with the ice detector.

3. Installation according to claim 1 or 2, characterized in that the defroster clock interacting with the ice detector and the ice detector are connected, via a flipflop or an OR gate, to the defrosting means.

4. Installation as described hereinabove and/or illustrated in the accompanying figure.

Drawing