GB1598601A

GB1598601A - Thawing device for low temperature refrigerator counters

Info

Publication number: GB1598601A
Application number: GB20543/78A
Authority: GB
Original assignee: ARNEG
Current assignee: ARNEG
Priority date: 1977-12-19
Filing date: 1978-05-18
Publication date: 1981-09-23
Also published as: FR2412039A1; FR2412039B3; AT355062B; SE7811041L; DE2821580A1; PT68119A; ES470860A1; FI783328A; IT1089232B; ATA374878A

Description

(54) THAWING DEVICE FOR LOW TEMPERATURE REFRIGERATOR COUNTERS (71) We, SOC. ARNEG S.P.A., a company organised under the law of the Italian Republic, of Marsango Di Campo San Martino (Padova), Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to a thawing device for low temperature refrigerator counters, and more precisely for counters of the type comprising an upwardly open compartment for containing products to be preserved at low temperature, a refrigerating circuit evaporator disposed under the compartment, and at least one fan inserted with the evaporator in a ventilation channel extending below the compartment and to the side thereof to induce low-speed circulation of ventilating air which completes its cycle by way of the open upper part of the containing compartment.

In counters of this type, the necessary periodical thawing is carried out by using the heat generated by suitably disposed electric heater elements or by hot gas circulated through suitable pipes.

Both these methods give rise to various drawbacks (economical, operational, bulk etc.), which the present invention proposes to obviate.

The invention provides a thawing device for refrigerator counters of the aforesaid type, comprising electrical circuit means which, controlled, cause the fan to reverse its motion and increase its speed, so as to create in the ventilation channel a circulation of high speed air of reverse direction which completes its cycle externally of the containing compartment.

It is apparent that the result of increasing the fan speed during the thawing stage is to circulate not only the refrigerated air already contained in the inner compartment of the counter, but also, and more especially, the hot ambient air, which is thus passed at speed through the evaporator thus limiting its own temperature reduction and instead raising the temperature of the evaporator, with consequent thawing of the evaporator. A further effect of reversing the motion of the fan is that the flow of hot air drawn in by the fan strikes the evaporator at that end which up to that time was at the lowest temperature, so making the temperature of the evaporator uniform and ensuring a better thawing efficiency than would be otherwise obtained with unidirectional ventilation.Periodical thawing of the inner compartment of the refrigerator counter is therefore obtained in a manner which is operationally and constructionally very simple (basically, the only requirements are a speed regulator and a change-over switch, preferably controlled by a timer).

In comparison with the present-day electric heater element or hot gas systems, the device according to the invention has the following advantages: a) The additional electrical components required for operating the heater elements, such as contactors, pressure switches, thermostats etc., are no longer required; b) The pipes, valves etc. required for using hot gas are no longer required; c) There is no longer very high temperature close to the evaporator, with consequent minor overloading of the electric motor of the refrigerating circuit compressor on startup after thawing; d) The components used can be reduced to a minimum, so that any need for servicing due to faults is practically non-existent;; e) There is a smaller electricity consumption than in the case of thawing using electric heater elements, together with a total absence of risk due to short-circuits or to bad earthing of the installation; f) The merchandise no longer suffers excessive temperature changes, and thus is preserved longer and in excellent condition.

The characteristics and advantages of the present invention will be more apparent from the detailed description given hereinafter of one embodiment of a low temperature refrigerator counter provided with a thawing device according to the invention. This detailed description refers by way of example to the accompanying drawings, in which:: Figure 1 is a sectional plan view of the refrigerator counter on the line II of Figure 2; Figure 2 is a cross-section through the refrigerator counter on the line II--II of Figure 1, with arrows showing the ventilating air circulation during the normal operation of the counter; Figure 3 is a section through the counter similar to Figure 2, but with arrows showing the air circulation during thawing; Figure 4 is a diagram of the electrical circuit means which operate the thawing of the counter refrigerator shown in the previous figures.

Figures 1, 2 and 3 show a refrigerator counter I provided with an outer insulated housing 2 with lateral sides 7, and an inner chest 3 defining an upwardly open inner compartment 4 for containing the products to be preserved.

Between the housing 2 and chest 3 there is defined a substantially U-shaped channel 5 which extends below, and to the sides of, the inner compartment 4. In the space defined between the base of the inner chest 3 and the base of the outer housing 2 there are housed an evaporator 6 (forming part of a conventional refrigerating circuit not shown on the drawings) and two fans 8 normally driven at low speed to circulate ventilating air in the direction indicated by the arrows 9 in Figure 2, and which completes its cycle by way of the upper open part of the inner compartment 4.

As will be more apparent hereinafter, during thawing the two fans 8 are rotated in the opposite direction at high speed to create circulation in the opposite direction, shown by the arrows 10 in Figure 10, and which chiefly involves the hotter external air.

The two fans 8 are caused to run with this reverse motion at the different speed by the electrical supply and control circuit shown in Figure 4. This circuit comprises two supply terminals 11 and 12, the first being the phase terminal and the second the neutral, which are connected conventionally in known manner to a normal source of mains voltage. The neutral terminal 12 is directly connected to a corresponding terminal on the fans 8, whereas these latter receive the necessary phase voltage either at a first forward running terminal via a rheostat speed regulator 13, or at a second reverse running terminal directly from the phase terminal 11, according to whether a relay 14 is de-energised or energised.This relay comprises a changeover contact 15 and an electrical winding 16, which is connected between the two terminals l l and 12, and therefore energised, by the action of a timer 17 which includes a change-over contact 18 controlled by a timing device 19.

During the normal operation of the refrigerator counter, the mobile contact 18 of the timer 17 is in the rest position of Figure 4, as is the mobile contact 15 of the relay 14.

Under these conditions, the two fans 8 are supplied at their respective forward running terminals via the speed regulator 13, and consequently rotate at low speed in a direction such as to induce normal circulation of ventilating air, as shown by the arrows 9 in Figure 2.

The commencement and termination of thawing are controlled at the appropriate times by the timer 17, which, when its mobile contact 18 changes over, causes energisation of the relay 14, the mobile contact 15 of which then disconnects the speed regulator 13 and connects the reverse running terminal of the fans 8 directly to the phase terminal 11. These fans then rotate in the reverse direction at high speed, to create the air circulation illustrated by the arrows 10 in Figure 3. The external hot air, which is drawn in by the fans 8 and fed across the evaporator 6 starting from that end thereof which up to that moment was at the lowest temperature, can thus thaw the inner chamber of the counter and at the same time raise and make uniform the temperature of the evaporator 6.

WHAT WE CLAIM IS: 1. A thawing device for low temperature refrigerator counters of the type comprising an upwardly open compartment for containing products to be preserved at low temperature, a refrigerating circuit evaporator disposed below the compartment, and at least one fan inserted with the evaporator in a ventilation channel which extends below the compartment and laterally thereto, to induce a low-speed circulation of ventilating air which completes its cycle by way of the open upper part of the containing compartment, comprising electrical circuit means which, when controlled, cause the fan to reverse its motion and increase its speed, so as to create in the ventilation channel a circulation of high speed air of reverse direction which completes its cycle externally of the containing compartment.

2. A device as claimed in claim 1, wherein the electrical circuit means comprise a change-over relay for the electrical supply of the fan at different voltages to respective forward running and reverse running termi

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. excessive temperature changes, and thus is preserved longer and in excellent condition. The characteristics and advantages of the present invention will be more apparent from the detailed description given hereinafter of one embodiment of a low temperature refrigerator counter provided with a thawing device according to the invention. This detailed description refers by way of example to the accompanying drawings, in which:: Figure 1 is a sectional plan view of the refrigerator counter on the line II of Figure 2; Figure 2 is a cross-section through the refrigerator counter on the line II--II of Figure 1, with arrows showing the ventilating air circulation during the normal operation of the counter; Figure 3 is a section through the counter similar to Figure 2, but with arrows showing the air circulation during thawing; Figure 4 is a diagram of the electrical circuit means which operate the thawing of the counter refrigerator shown in the previous figures. Figures 1, 2 and 3 show a refrigerator counter I provided with an outer insulated housing 2 with lateral sides 7, and an inner chest 3 defining an upwardly open inner compartment 4 for containing the products to be preserved. Between the housing 2 and chest 3 there is defined a substantially U-shaped channel 5 which extends below, and to the sides of, the inner compartment 4. In the space defined between the base of the inner chest 3 and the base of the outer housing 2 there are housed an evaporator 6 (forming part of a conventional refrigerating circuit not shown on the drawings) and two fans 8 normally driven at low speed to circulate ventilating air in the direction indicated by the arrows 9 in Figure 2, and which completes its cycle by way of the upper open part of the inner compartment 4. As will be more apparent hereinafter, during thawing the two fans 8 are rotated in the opposite direction at high speed to create circulation in the opposite direction, shown by the arrows 10 in Figure 10, and which chiefly involves the hotter external air. The two fans 8 are caused to run with this reverse motion at the different speed by the electrical supply and control circuit shown in Figure 4. This circuit comprises two supply terminals 11 and 12, the first being the phase terminal and the second the neutral, which are connected conventionally in known manner to a normal source of mains voltage. The neutral terminal 12 is directly connected to a corresponding terminal on the fans 8, whereas these latter receive the necessary phase voltage either at a first forward running terminal via a rheostat speed regulator 13, or at a second reverse running terminal directly from the phase terminal 11, according to whether a relay 14 is de-energised or energised.This relay comprises a changeover contact 15 and an electrical winding 16, which is connected between the two terminals l l and 12, and therefore energised, by the action of a timer 17 which includes a change-over contact 18 controlled by a timing device 19. During the normal operation of the refrigerator counter, the mobile contact 18 of the timer 17 is in the rest position of Figure 4, as is the mobile contact 15 of the relay 14. Under these conditions, the two fans 8 are supplied at their respective forward running terminals via the speed regulator 13, and consequently rotate at low speed in a direction such as to induce normal circulation of ventilating air, as shown by the arrows 9 in Figure 2. The commencement and termination of thawing are controlled at the appropriate times by the timer 17, which, when its mobile contact 18 changes over, causes energisation of the relay 14, the mobile contact 15 of which then disconnects the speed regulator 13 and connects the reverse running terminal of the fans 8 directly to the phase terminal 11. These fans then rotate in the reverse direction at high speed, to create the air circulation illustrated by the arrows 10 in Figure 3. The external hot air, which is drawn in by the fans 8 and fed across the evaporator 6 starting from that end thereof which up to that moment was at the lowest temperature, can thus thaw the inner chamber of the counter and at the same time raise and make uniform the temperature of the evaporator 6. WHAT WE CLAIM IS:

1. A thawing device for low temperature refrigerator counters of the type comprising an upwardly open compartment for containing products to be preserved at low temperature, a refrigerating circuit evaporator disposed below the compartment, and at least one fan inserted with the evaporator in a ventilation channel which extends below the compartment and laterally thereto, to induce a low-speed circulation of ventilating air which completes its cycle by way of the open upper part of the containing compartment, comprising electrical circuit means which, when controlled, cause the fan to reverse its motion and increase its speed, so as to create in the ventilation channel a circulation of high speed air of reverse direction which completes its cycle externally of the containing compartment.

nals on the fan, and a timer for controlling the change-over of the relay.

3. A thawing device for low temperature refrigerator counters substantially as herein described and with reference to the accompanying drawings.