GB2351798A

GB2351798A - Installation for maintaining an isothermal chamber at a low temperature

Info

Publication number: GB2351798A
Application number: GB0009185A
Authority: GB
Inventors: Andre Churi
Original assignee: LAMBERET CONST ISOTHERMES
Current assignee: LAMBERET CONST ISOTHERMES
Priority date: 1999-04-14
Filing date: 2000-04-14
Publication date: 2001-01-10
Anticipated expiration: 2020-04-14
Also published as: FR2792398B1; ITMI20000784A1; ITMI20000784A0; GB0009185D0; GB2351798B; ES2195679A1; ES2195679B1; DE10018885A1; IT1317209B1; FR2792398A1

Abstract

A casing (5) forming cold reserve of an isothermal box (4) is equipped with a stack of cold accumulating plates (6) behind a door (12). The casing is of insulating material, and is made in such a way that it can be fixed against the ceiling (4) of the isothermal box forming a closed chamber. The casing includes in a vertical face, an air inlet aperture (13), and in its base and opposite the inlet aperture (13), an air outlet aperture (14) associated with a fan (15). The fan (15) is capable of generating an air flow in the casing (5) directed from the inlet aperture (13) towards the outlet aperture (14) and circulating between the cold accumulating plates (6). The electric motor of the fan (15) is supplied by an electrical circuit (16) comprising a thermostatic unit (17) operating the circuit under the control of a temperature sensor (21) disposed in the storage compartment. Each of the inlet (13) and outlet (14) apertures respectively is associated with dampers (24) which come into the open position when the fan is operating. Each plate (6) is of moulded synthetic material containing a eutectic mixture.

Description

1 2351798 AN INSTALUTION FOR MAINTAD(ING AN ISOTHERMAL CHAMBEK AT A LOW

TEMPERATURE The present invention relates to an installation for maintaining an isothermal chamber at a low temperature.

The storage of various products at a low temperature, namely between OOC and 70C, in an isothermal chamber having insulating walls is generally ensured:

either by means of the evaporator of a refrigerated installation, for example, in a fixed installation or in a 10 refrigerated truck, - or by means of plates accumulating cold, also known as eutectic plates, which, composed of an envelope made of a synthetic material containing an aqueous mixture freezing is well below the temperature of use and previously charged with cold in a freezer bringing them to a negative temperature, are disposed inside a compartment forming a cold reserve, but communicating permanently with a storage compartment disposed below it, 20 - or finally by means of ice or solid carbon dioxide disposed in a cold reserve separated from the storage compartment by an insulating wall.

By reason of its investment cost, use of refrigeration equipment is only possible for large volume chambers and therefore cannot be considered for chambers with a small volume, namely of the order of 2 m3, of the type used by caterers or others in the food industry providing 30 deliveries.

The same applies for preservation by means of ice or solid carbon dioxide which requires either means for supplying carbon dioxide in the liquid phase, or means for cryogenic 35 storage, for which the investment is too high for small unit volume applications.

2 As regards plates accumulating cold, these prove to be unsatisfactory since they can only be used for a short period, and are also inconsistent.

Indeed, they are generally disposed in a reserve communicating permanently with the storage compartment, without any regulation, so that these plates have the tendency to lose their calories by conduction with the surrounding air, circulating by convection in the storage compartment. The result is that these plates lose the calories which they have accumulated more rapidly than they should, with the consequent risk of the storage compartment being allowed to reach an ambient temperature higher than the recommended threshold before the desired time, breaking in this way what may be called the cold chain.

In addition, at the start of the storage cycle, i.e. when they are deposited at a negative temperature in the cold reserve, they have the tendency to bring the products nearest to them, including those which must be preserved, to a negative temperature, which is detrimental for some of them such as vegetables and in particular salads.

An object of the invention is therefore to provide an installation for maintaining a low temperature which has a low investment and operating cost, which is simple to use, reliably maintains a constant temperature over a desired period, without any damage to the products stored, and which can be adapted to low volume isothermal chambers.

These low volume chambers, whether they be disposed in the rear part of a van or in a trailer or consist of a movable container, are of interest more particularly to small firms which, having available limited financial resources, cannot currently consider equipping the chamber with a refrigerating installation or making available a unit for distributing solid carbon dioxide.

3 Currently, this type of user places the food products to be stored in small-size containers containing eutectic plates, and places the containers in the isothermal chamber, so as to limit heat losses. These users wish to have an installation available which not only can be installed rapidly in the chamber, but can also be removed at the least cost, for example when the vehicle, trailer or container is replaced.

Another object of the invention is to provide an installation which is ready to be installed and which is removable, and which can be installed in any isothermal chamber and rapidly dismantled therefrom, and more particularly in the isothermal box, whether removable or not, of a delivery van.

This installation comprises a casing delimiting the cold reserve and which is capable of receiving several superimposed and/or juxtaposed plates for accumulating cold, which are detachable and rechargeable by placing them in a freezer or the equivalent.

According to the invention, the casing is equipped with a door, is made of insulating material, and is made in such a way that it can be fixed against the ceiling of the isothermal box forming a closed chamber, and includes, in a vertical face, an air inlet aperture, and in its base and opposite the inlet aperture, an air outlet aperture associated with a fan, the said fan being capable of generating an air flow in the casing directed from the inlet aperture towards the outlet aperture and circulating between the cold accumulating plates while, on the other hand, the electric motor of the fan is supplied by an electrical circuit comprising a thermostatic unit closing this circuit under the control of a temperature sensor disposed in the storage compartment and, on the other hand, each of the inlet and outlet apertures is associated with 4 means of obstruction coming into the open position when the fan is operating.

Accordingly, when the fan is at rest, the accumulator plates are confined in the insulating casing of which the air inlet and outlet apertures respectively are closed, which prevents any heat exchange with the isothermal chamber and considerably reduces heat losses from the accumulator plates. As soon as the sensor, disposed in the chamber, detects a rise in temperature beyond a threshold value, the thermostatic unit orders the closing of the electrical circuit of the fan which first of all generates variations in pressure in the casing, bringing about the opening of the apertures, and then produces a directed air flow. This flow extracts the stagnant warmer air which is against the ceiling of the isothermal chamber and forces it to circulate between the accumulator plates so that, after cooling it against these plates and after returning it to the chamber, it can reduce the temperature in this chamber constituting the storage compartment.

As soon as the temperature in the chamber returns to a lower threshold value, the thermostatic unit initiates the opening of the electrical circuit of the fan, which once again confines the plates in the casing by closing the air apertures.

By virtue of this, the cold accumulated by the plates is only used as required by the products disposed in the chamber and stored for a long time, so that this installation can ensure that the low temperature is maintained over a greater period of time and can guarantee the preservation of the cold chain.

This installation has the following supplementary advantages:

- it is silent in operation, - its electrical energy consumption is low and it may therefore be supplied by a vehicle battery, 5 - the accumulator plates are recharged with cold outside the chamber, for example in a conventional freezer using mains power and this only requires a period equivalent to one night, - its installation time, which is of the order of two hours, is several times less than the installation time of more costly refrigerating equipment, - it can be easily demounted in order to be retrieved, for example in the case of a vehicle replacement.

In one embodiment of the invention, each of the apertures, the air inlet and outlet apertures respectively, is formed of two parallel slits and the face of each slit which is downstream relative to the direction of the circulation of the air flow, is obstructed by a flap made of synthetic material fixed to one of its edges and capable, on the one hand, of lifting in the presence of the air flow generated by the fan, and on the other hand, of returning elastically against the slit as soon as the air flow is interrupted.

When these flaps are in a closed position, they oppose any circulation of air between the casing and the chamber, including that caused by natural convection. They thus ensure, in a simple and low-cost manner, that cold is confined in the insulating casing.

Advantageously, each of the cold accumulating plates is composed of a central body which is corrugated longitudinally and of two lateral shoulders extending from 6 each side of the central body, each shoulder being formed between an upper rib projecting upwards and a lower rib projecting downwards, so that, by superimposing the plates, corrugated passageways are formed for the directed 5 circulation of the air flow.

This arrangement also has the advantage of simplifying the construction of the casing, since the inner walls do not require ribs for accommodating and positioning the accumulator plates, which are positioned on each other simply by stacking.

other characteristics and advantages will become apparent from the following description with reference to the accompanying diagrammatic drawings representing, by way of example, an embodiment of this installation in the case of its application to a van.

Figure 1 is a side view, with a partial cut-away, of a vehicle equipped with the installation, Figure 2 is a partial view, in cross section, showing the installation on an enlarged scale, Figure 3 is a perspective view of an embodiment of an accumulator plate, Figure 4 is a cross section along IV-IV of figure 2, Figure 5 is a longitudinal section of an accumulator plate.

In figure 1, the numerical reference 2 designates, in a general manner, a vehicle of the box van type, of which the rear compartment 3, accessible through side or rear doors, not shown, contains an isothermal box 4, which is demountable or not, forming a storage compartment.

7 The installation, according to the invention, is essentially composed of a casing 5 capable of accommodating a cold accumulator plate 6. The casing is made of an insulating material and, in the embodiment shown, has, as shown in figure 4, a U-shaped cross section of which the arms 5a, 5b are provided with outer elbowed flanges 7a, 7b for fixing it by means of screws 8 against the ceiling 9 of the isothermal chamber 4. This casing, which is disposed in the angle formed between the ceiling 9 and one of the vertical walls of the isothermal box and, in this embodiment, the front wall 10 of this box, includes a front wall 12 opposite this wall. In this embodiment, this consists of a door. This door, which enables the accumulator plates 6 to be introduced into the casing 5, may of course be disposed on one of the longitudinal walls of this casing if this occupies another position in the vehicle and is for example transverse.

The casing is equipped with an inlet aperture 13 and an outlet aperture 14 disposed either side of the zone for receiving the accumulator plates 6, namely in the door 12 and in the bottom of the casing respectively, opposite the door 12 and therefore close to the front wall 10 of the isothermal chamber.

The outlet aperture 14 is associated with an electric fan 15 of which the electrical circuit 16 passes through the wall 10 to arrive at a thermostatic unit 17, positioned in the driving compartment of the vehicle, i.e. outside the isothermal box 4. This unit is itself supplied via a general switch 18, by means of a circuit 19, connected to the battery of the vehicle. Firstly, a circuit 20 connected to the temperature sensor 21disposed in the storage compartment of the isothermal chamber also ends in this unit and secondly, optionally, a circuit 22 ends in another temperature sensor 23 disposed close to the accumulator plates 6.

8 Each of the inlet 13 and outlet 14 apertures respectively is associated with means of obstruction coming into the open position when the fan is operating.

In the embodiment shown, each aperture 13 and 14 is formed of parallel slits 13a, 14a and each slit is associated with a flap made of synthetic material 24 fixed to the edge of this slit and capable of obstructing it elastically. These elastic flaps are disposed on the face of the inlet apertures which is downstream in relation to the direction of the air flow generated by the fan 15, represented by the arrow 31 in figure 2.

As shown in greater detail in figures 3 to 5, each of the is accumulator plates 6 is composed of a central corrugated body 6a, and two side shoulders 6b, extending longitudinally either side of the central body and giving this plate a cross section having the general shape of an H. In a known manner, each plate is composed of an envelope made of moulded synthetic material and contains an aqueous mixture 26 of which the freezing point is determined in relation to the quantity of calories which need to be stored, and as a consequence, of the desired storage time.

As shown in greater detail in figure 4, each shoulder 6b is formed between an upper rib 27 projecting upwards and a lower rib 28 projecting downwards. The two lower ribs 28 of each plate are formed so as to be housed between the inner faces of the upper ribs 27 and a subjacent plate 6. The bottom of the casing 5 includes grooves 29 able to cooperate with the lower ribs 28 of the lowest plate, in order to position it and wedge it in translation.

By virtue of this'arrangement, simply by stacking the plates 6 in the casing 5 ensures that these plates are positioned and wedged in transverse translation, while 9 forming corrugated passageways 30 between them for the circulation of the air flow.

With this installation, when the temperature in the storage compartment, i.e. in the isothermal chamber outside the casing 5, reaches a threshold value, and for example 60C for the storage of fresh products, the thermostatic unit 17, instructed by the sensor 21, orders the electrical circuit 16 to be closed and the fan 15 to be put into operation. Putting this fan into operation results in the generation of a reduction in pressure on the inlet aperture 13, and a pressure on the outlet aperture 14 which causes the flaps 24 of the slots, 13a, 14a respectively to move away and to establish an air flow oriented in the direction of the arrow 31. Under these conditions, the warmest air, accumulated against the ceiling 4 of the isothermal chamber, is extracted into the casing 5. It is forced to circulate therein in the corrugated passage ways 30 between the accumulator plate 6. This forced circulation ensures that the air is cooled before it is returned through the outlet aperture 14 into the storage compartment of the isothermal chamber.

As soon as the temperature in this box has reach('d a lower threshold value, for example 40C, the thermostatic unit 17 opens the electric circuit 16 and causes the fan 15 to stop. As soon as this stop occurs, the elastic flaps 24 take up a closed position and therefore oppose any heat exchange by convection between the casing 5 and the isothermal chamber 4.

Accordingly, the calories accumulated in the plates 6 are only consumed as required, so that, for a quantity of calories accumulated, overconsumption is prevented and the period is increased during which the required temperature is maintained.

moreover, confinement of the plates in the casing prevents their negative temperature from being transmitted at the start of the storage cycle to the nearest stored products and prevents any risk of burning or spoiling by negative 5 cold.

It will be noted that, in order to facilitate the circulation of air being cooled between the plates 6, the base 5 of the casing is inclined downwards from the inlet aperture 13 to the outlet aperture 14, so as to give the same inclination to the passageways 30 delimited between the plates.

This installation is very simple to achieve, since it is sufficient to attach the casing against the ceiling of the isothermal box 4 and to pass the electrical circuits 16, 20 and 22, connected to the unit 17 positioned in the cab, through the bottom wall of this box. The time taken for this installation is of the order of an hour and a half to two hours, and it is thus very much less than the twelve hours needed to install refrigerating equipment. It is the same for dismantling which is carried out much more rapidly, so that the installation can be easily retrieved in order to be mounted in another chamber, and this by non- specialized personnel.

The sensor 23 only takes part in the operation of the installation in order to cut off the circuit supplying the fan when the accumulator plates 6 are no longer able to supply cold. It therefore has the function of preventing electrical power being consumed which could drain the batteries of the vehicle and of causing the fan 15 to revolve if the switch 18 has inadvertently not been actuated after the isothermal chamber has been unloaded.

The installation according to the invention not only makes it possible to use the cold accumulated in the eutectic 11 plates 6 under the best conditions, but also to obtain a temperature in the storage compartment which is regulated between limits which can be adjusted by the thermostatic unit, actuated from outside.

12

Claims

1. Detachable installation for maintaining a removable isothermal box (4) at a low temperature, comprising a casing (5) delimiting the cold reserve and capable of receiving several superimposed and/or juxtaposed plates (6) for accumulating cold, which are detachable and rechargeable by placing them in a freezer or the equivalent, characterized in that the casing (5), is equipped with a door (12), is made of insulating material, and is made in such a way that it can be fixed against the ceiling (4) of the isothermal box forming a closed chamber, and includes, in a vertical face, an air inlet aperture (13), and in its base and opposite the inlet aperture (13), an air outlet aperture (14) associated with a fan (15), the said fan (15) being capable of generating an air flow in is the casing (5) directed from the inlet aperture (13) towards the outlet aperture (14) and circulating between the cold accumulating plates (6) while, on the one hand, the electric motor of the fan (15) is supplied by an electrical circuit (16) comprising a thermostatic unit (17) closing this circuit under the control of a temperature sensor (21) disposed in the storage compartment and that, on the other hand, each of the inlet (13) and outlet (14) apertures respectively is associated with means of obstruction (24) coming into the open position when the fan is operating.

2. Installation according to claim 1, characterized in that each of the air inlet (13) and air outlet (14) apertures respectively, is formed of two parallel slits (13a, 14a) and the face of each slit which is downstream, in relation to the direction of circulation of the air flow, is obstructed by a flap made of synthetic material (24) fixed to one of its edges and capable, on the one hand, of lifting in the presence of the air flow generated by the fan (15), and on the other hand, of returning 13 elastically against the slit as soon as the air flow is interrupted.

3. Installation according to claim 1, characterized in that a second temperature sensor (23) is disposed in the casing (5) close to one of the accumulator plates (6) and is connected to a thermostatic unit (17) opening the electrical supply circuit (16) of the fan (15) when the temperature detected by the sensor reaches a reference value.

4. Installation according to claim 1, characterized in that each of the cold accumulator plates (6) is composed of a central body (6a), which is corrugated longitudinally, and of two lateral shoulders (6b) extending from each side of the central body, each shoulder (6b) being formed between an upper rib (27) projecting upwards and a lower rib (28) projecting downwards, so that, by superimposing the plates (6), corrugated passageways (30) are formed for the directed circulation of the air flow.

5. Installation according to claim 1, characterized in that the casing (5) has a U-shaped cross section of which the arms (5a, 5b) are provided with outer elbowed flanges (7a, 7b) and is fixed against the ceiling of the chamber (4) and in the angle formed between this ceiling and one of the vertical walls of the box, this attachment being ensured by connecting means (8) fixed in the ceiling and traversing the elbowed flanges (7a, 7b) of the casing (5) -

6. Installation according to claim 1, characterized in that the base of the casing (5) is inclined downwards from the inlet aperture (13) towards the outlet aperture (14).

7. A detachable installation substantially as hereinbefore described with reference to the drawings.

7. A detachable installation substantially as hereinbefore described.

8. A detachable installation substantially as hereinbefore described with reference to the drawings.

Amendments to the claims have been filed as follows 113 CLAIMS Detachable installation for a vehicle, the installation being for maintaining a removable isothermal box (4) at a low temperature, comprising a casing (5) delimiting the cold reserve and capable of receiving several superimposed and/or juxtaposed plates (6) for accumulating cold, which are detachable and rechargeable by placing them in a freezer or the equivalent, each of the cold accumulator plates (6) being composed of a central body (6a) which is corrugated longitudinally, and of two lateral shoulders (6b) extending from each side of the central body, each shoulder (6b) being formed between an upper rib (27) projecting upwards and a lower rib (28) projecting downwards, so that by superimposing the plates (6), corrugated passageways (30) are formed for the directed circulation of air flow. The casing (5) being equipped with a door (12), is made of insulating material, and is made in such a way that it can be fixed against the ceiling (4) of the isothermal box forming a closed chamber, and includes, in a vertical face, an air inlet aperture (13), and in its base and opposite the inlet aperture (13), an air outlet aperture (14) associated with a fan (15), the said fan (15) being capable of generating an air flow in the casing (5) directed form the inlet aperture (13) towards the outlet aperture (14) and circulating between the cold accumulating plates (6) while, on the one hand, the electric motor of the fan (15) is supplied by an electrical circuit (16) comprising a thermostatic unit (17) closing this circuit under the control of a temperature sensor (21) disposed in the storage compartment and that, on the other hand, each of the inlet (13) and outlet (14) apertures respectively is associated with means of 1 obstruction (24) coming into the open position when the fan is operating.

2. Installation according to claim 1, characterised in that each of the air inlet (13) and air outlet (14) apertures respectively, is formed of two parallel slits (13a and 14a) and the face of each slit which is downstream, in relation to the direction of circulation of the air flow, is obstructed by a flap made of synthetic material (24) fixed to one of its edges and capable, on the one hand, of lifting in the presence of the air flow generated by the fan (15), and on the other hand, of returning elastically against the slit as soon as the air flow is interrupted.

3. Installation according to claim 1, characterised in that a second temperature sensor (23) is disposed in the casing (5) close to one of the accumulator plates (6) and is connected to a thermostatic unit (17) opening the electrical supply unit (16) of the fan (15) when the temperature detected by the sensor reaches a reference value.

4. Installation according to claim 1, characterised in that the casing (5) has a U-shaped cross section of which the arms (5a, 5b) are provided with outer elbowed flanges (7a, 7b) and is fixed against the ceiling of the chamber (4) and in the angle formed between this ceiling and one of the vertical walls of the box, this attachment being ensured by connecting means (8) fixed in the ceiling and traversing the elbowed flanges (7a, 7b) of the casing (5).

13 5. Installation according to claim 1, characterised in that the base of the casing (5) is inclined downwards from the inlet aperture (13) towards the outlet aperture (14).

6. A detachable installation substantially as hereinbefore described.