EP0631097A1

EP0631097A1 - Cooling unit for coffins with detachable refrigerating plate and liquid recovery

Info

Publication number: EP0631097A1
Application number: EP94108336A
Authority: EP
Inventors: Mario Bernasconi
Original assignee: NUOVA ZORSOL Srl
Current assignee: NUOVA ZORSOL Srl
Priority date: 1993-06-22
Filing date: 1994-05-30
Publication date: 1994-12-28
Anticipated expiration: 2014-05-30
Also published as: ES2148256T3; ITMI931333A0; DE69424090D1; EP0631097B1; ITMI931333A1; ATE192231T1; IT1264864B1; DE69424090T2

Abstract

Cooling unit for coffins comprising a refrigerating circuit in which a first heat exchange fluid circulates therein and a second circuit in which a second heat exchange fluid circulates, connected with a refrigerating plate in a condition of heat exchange with the coffin. The plate is of disposable kind i.e. detachable from the remaining of the cooling unit and left into the coffin after the final closure thereof. Means are also provided to allow the draining of the heat exchange fluid from the refrigerating plate and the recovery of said fluid in a suitable tank to allow the reuse of the remaining part of the cooling unit by insertion of other plates.

Description

The present invention concerns a cooling unit for coffins comprising a refrigerating circuit and a refrigerating plate which is in a situation of heat exchange with the interior of the coffin.
More particularly the invention concerns a cooling unit of the above-mentioned kind wherein the cooling unit consists of a detachable coil which a heat exchange refrigerating fluid flows therein.
Similar cooling units are known in the art, for instance the one described in the European Patent N° EP 230.595 of the same applicant.
The above embodiment includes a freon circulating cooling unit consisting of two parts, the first comprises all the elements of the refrigerating circuit, preferably contained in a transportable container, the second, namely the plate constituting the evaporator, consists of a preloaded coil connectable with, or detachable from the remaining part of the unit by means of rapid connections set up on the delivery and exit pipes to seal the corresponding parts of the refrigerating circuit after the relative detachment. All elements of the refrigerating circuit, with the exclusion of the plate, can be subsequently reused to be connected to another plate associated with another coffin.
On the contrary, the plate is a disposable element and it is left in the coffin after the final closure thereof, involving therefore the loss of the freon contained therein. It has to be considered that the amount of freon contained into the evaporator, in the normal operating conditions, is remarkably higher than the preloaded amount at room temperature.
Other losses, even though less substantial, take place at the time of disconnecting the evaporator from the remaining part of unit in correspondence of the rapid attachments, said losses being due to a difference between the pressure of freon contained in the coil and the external atmospheric pressure.
One of the drawback of the above cooling unit is due to the fact that, by using many times the reusable part of the refrigerating circuit, a gradual decrease of the amount of the fluid in the circuit takes place. Such decrease implies frequent and expensive circuit refilling operations as well as the availability of a tank of such a size as to contain a sufficient amount of fluid to assure a suitable operating duration to the reusable unit.
An additional drawback is due to the harmless freon leaking in the atmosphere, since, as it is well known, freon is a polluting fluid.
It is an object of the present invention to provide an improved cooling unit allowing the use of a detachable refrigerating plate, while avoiding any polluting fluid leaking.
Another object of the present invention is to provide a cooling unit which allows to recover the excess fluid contained in the refrigerating plate before its detachment from the remaining part of the cooling unit.
A further object of the present invention is to provide a cooling unit allowing to limit the fluid losses during detachment of the plate from the remaining part of the cooling unit.
The above objects are attained by the present invention which refers to a cooling unit for coffins of the kind comprising a refrigerating circuit in which a first heat exchange fluid circulates therein, at least a refrigerating plate in a situation of heat exchange with the interior of the coffin and at least a device to carry out the flowing of a second heat exchange fluid in a second circuit which said refrigerating plate is connected with, said refrigerating plate consisting of a coil set up detachable from the remaining part of the circuit with which is connected, characterized in that it comprises means to actuate the operation of said device for the circulation of said second heat exchange fluid and means to stop the flowing of said second fluid in said second circuit, allowing the draining of said fluid from said coil, said actuating means being able to stop the operations of said flowing device when the amount of said second fluid in said coil is lower than a predetermined value.
Therefore, according to the invention, it is possible to carry out a fluid recovery operation from the refrigerating plate before the disconnection of said plate from the remaining part of the refrigerating circuit.
This and other advantages will appear more clearly from the following description which is provided with reference to the annexed drawings to illustrate the invention without any limiting purpose.
In the drawings:

Fig. 1 is a schematic view of a first embodiment of the cooling unit according to the invention; and
Fig 2 is a schematic view of a second embodiment according to the invention.

In the first embodiment according to invention said second circuit coincides with the cooling circuit and the heat exchange fluid is a freon containing refrigerating fluid.
The cooling circuit shown in Fig. 1 comprises therefore a compressor 1 delivering the fluid in the gaseous state to a condenser 3 through a pipe 2. In the condenser 3, conventionally cooled by a fan 4, the fluid liquefies by condensation and is recovered in a tank 5. From said tank 5 the fluid passes through a pipe 6 up to the inlet of a valve or an expansion capillary 7 whose outlet is then connected, through a delivery pipe 8, with the inlet pipe 9 of the evaporator 10.
In the preferred embodiment of the invention the reusable part of the cooling unit is contained in a transportable container 20 (shown in dotted line in Fig. 1), while the refrigerating plate 25 comprises the evaporator 10 consisting of a refrigerating fluid preloaded flat coil 11, of the kind employed in the household refrigerators, known as roll-bond.
The outlet pipe 12 of the coil 11 is then connected with the return pipe 13 carrying back the fluid to compressor 1.
The connection between pipes 8 and 9, as well as the connection between pipes 13 and 12, is achieved by means of rapid connections 14 connectable and detachable with respect to the corresponding rapid connections 15.
According to an advantageous embodiment of the invention a stop-valve 16 is provided on the refrigerating fluid delivery pipe upstream of the valve or the expansion capillary 7. This arrangement allows to discontinue the refrigerating fluid flow toward the evaporator 10 in a portion of the circuit in which said fluid is in liquid state.
Upstream of the evaporator 10 and on the pipe 13 an automatic single-acting valve, acting as a nonreturn valve, is preferably provided, said valve allows the refrigerating plate 25 isolation from the remaining part of the circuit before its detachment.
In order to discharge the refrigerating fluid from the refrigerating plate 25, before disconnecting said plate from the remaining part of the circuit, the valve 16 is turned off on the delivery pipe 8 and, simultaneously, the compressor 1 is switched on to draw the fluid from the coil 11 toward the reusable circuit part.
Once a sufficient emptying degree of the coil 11 is reached, the compressor 1 is shut off while the automatic, single-acting valve 17 prevents any return of the fluid to coil 11.
It is preferable that compressor 1 is operated independently of the temperature conditions of the refrigerating fluid, that, in the conventional cooling units, determinate the switch on or the shut off of the compressor during the usual operating cycles.
Such an arrangement may be obtained by parallel connecting suitable commutating devices, for instance a simple switch, with the contacts of the commutating device associated with the thermostat.
In such a way it is possible to carry out the coil 11 emptying in a fast and efficient manner independently of the usual operating cycle of the compressor 1.
In the preferred embodiment of the invention the coil 11 emptying cycle is carried out by means of suitable driving means comprising a control device 18 and at least a transducer 19 to provide information on the refrigerating fluid pressure conditions to the control device 18. To allow an entire automatization of the coil 11 emptying cycle it is advantageously used a control device 18 of the electromechanical or electronic kind, as well as an electrically actuated stop valve 16, as for instance a solenoid valve.
The coil 11 emptying cycle starts at the time in which the control device 18 receives a signal from the exterior, sent by an operator, for instance trough the electrical connection 21. The control device 18 reacts by actuating the closure of the stop valve 16 through the electrical connection 22, as well as the switch on of the compressor 1 through the electrical connection 23. The operation of the compressor 1 draws the refrigerating fluid from the coil 11 while the stop valve 16 plugs the delivery pipe upstream of the valve or expansion capillary 7.
During the coil 11 emptying, the transducer 19 provides the control device 18 with a variable electric signal as a function of the fluid pressure conditions downstream of the coil 11. The expression "variable electric signal" means either a continuous variable signal or a discontinuous variable signal, as for instance a two-level signal generated by respective conditions of open or closed circuit at the ends of the transducer.
When the refrigerating fluid pressure downstream of the coil goes below a predetermined threshold the transducer 19, through the electrical connection 24, indicates to the control device 18 the attainent of the optimum conditions to stop the coil 11 emptying cycle.
The control device 18 actuates then the switch off of the compressor 1 through the electrical connection 23 while the valve 17, suitably calibrated, avoids the fluid return into the coil 11.
In such a way it is possible to remarkably limit the amount of fluid remaining in refrigerating plate 25, reducing consequently the amount of the refrigerating fluid that, otherwise, will be lost by leaving the coil in the interior of the coffin.
By limiting the amount of fluid, and therefore its pressure inside the coil 11, the dispersion of the refrigerating fluid in the atmosphere is drastically reduced, if not eliminated.
In the second embodiment of the invention the refrigerating circuit is different from said second circuit and the above two circuits are heat exchange coupled by a heat exchanger.
The cooling unit according to the invention, as shown in Fig.2, comprises a conventional closed refrigerating circuit 30 in which a freon containing heat exchange fluid flows, and a second circuit wherein a liquid heat exchange fluid flows having a low freezing point and a high boiling point, for instance a glycol. The above two circuits are heat exchange, preferably counter-corrent, coupled by means of distinct hydraulic pipes in a heat exchanger 31.
By employing two distinct circuits, and particularly a sealed refrigerating circuit, the refrigerating fluid dispersion in the environment is eliminated.
More particularly, the second circuit of the cooling unit comprises a pump 32 for the second heat exchange fluid circulation, a tank 33 for the recovery of said second fluid and a refrigerating plate 34 in which a coil 35 is embedded.
The refrigerating plate 34 is detachable from the remaining part of the circuit in a point where a pair of joints 36 are present. Such joints are for instance neoprene made couplings placed respectively upstream of the inlet pipe 37 and downstream of the outlet pipe 38 of the heat exchange fluid in the coil 35.
The pump 32 acting as a heat exchange fluid circulating mean in the second circuit is preferably of positive-displacement kind. Said device allows to pump both the heat exchange fluid within the circuit and the necessary air to discharge the heat exchange fluid from the coil 35 and recovery same into the tank 33.
As a matter of fact, to carry out the emptying of the coil 35 a three way valve is provided, placed between the tank 33 and the pump 32, upstream of the latter with respect to the fluid flowing direction. Two ways of the valve are connected with the circuit, the third way is connected with the exterior to allow to pump air within the circuit and consequently draw the fluid from the coil 35. During the cooling unit normal operations the ways in communication with the remaining part of the circuit are open while the third way, in communication with the exterior, is closed.
The air inlet into the circuit allows then to recovery most of the heat exchange fluid that otherwise will be lost together with the refrigerating plate which is left in the coffin at the time the coffin is finally closed.
According to an advantageous feature of the invention, the coil 35 emptying operations are carried out in an automatic way by means of a control device 40 of electromechanical or electronic kind, furthermore the valve 39 is of electromechanical type, for instance an electrically driven solenoid valve.
In fact, before detaching the refrigerating plate 34, the operator sends a signal to the control device 40 through the electrical connection 41. The control device 40 actuates then the switching of the valve 39 through the electrical connection line 42 in order to close the way toward the tank 33 and put in connection the exterior with the portion of the circuit downstream of said valve.
In the same time of the switching of the valve 39, the control device 40 actuates, through the electrical connection line 43, the pump 32. The above operations give rise to the inlet of air into the circuit downstream of the valve 39 and the subsequent transfer of the heat exchange fluid through the circuit to the recovery tank 33.
A suitable sensor, for instance a thermal overloading sensor, allows the pump disconnection after a predetermined value of the coil emptying is reached. The plate 34 may therefore be detached from the reusable part of the cooling unit without any valuable loss of the heat exchange fluid.

Claims

Cooling unit for coffins of the kind comprising a refrigerating circuit in which a first heat exchange fluid circulates therein, at least a refrigerating plate in a situation of heat exchange with the interior of the coffin and at least a device to carry out the flowing of a second heat exchange fluid in a second circuit which said refrigerating plate is connected with, said refrigerating plate consisting of a coil, set up detachable from the remaining part of the circuit with which is connected, characterized in that it comprises means to actuate the operations of said device for the circulation of said second heat exchange fluid and means to stop the flowing of said second fluid in said second circuit and to allow the draining of said fluid from said coil, said actuating means being able to stop the operations of said flowing device when the amount of said second fluid in said coil is lower than a predetermined value.
Cooling unit according to claim 1, characterized in that said refrigerating circuit coincides with said second circuit and that said first heat exchange fluid coincides with said second fluid, said refrigerating circuit comprising a compressor for the circulation of said first or second heat exchange fluid, a condenser, one or more expansion valve or similar devices, an evaporator embedded into said refrigerating plate consisting of said preloaded coil, as well as a couple of rapid connections placed respectively upstream of the coil inlet pipe and downstream of the coil outlet pipe of said first or second heat exchange fluid to allow said coil connection to or removal from the remaining part of the refrigerating circuit.
Cooling unit according to claim 2, characterized in that said heat exchange fluid is a freon containing refrigerating fluid.
Cooling unit according to claim 2, characterized in that said heat exchange fluid stopping circulation means comprise at least a stop valve placed upstream of said expansion valve on the heat exchange fluid delivery pipe in the direction of the coil, as well as an automatic single-acting valve placed upstream of said compressor on the heat exchange fluid return pipe from said coil.
Cooling unit according to claim 4, characterized in that said actuating means comprise a control device able to effect the closure of said stop-valve on the delivery pipe toward said coil and control the switching on of said compressor, as well as at least a transducer to provide said control device with information on the refrigerating fluid pressure conditions to actuate the switching off of the compressor.
Cooling unit according to claim 5, characterized in that said control device is of electromechanical or electronic kind and that said stop-valve is an electrically actuated solenoid valve.
Cooling unit according to claim 5, characterized in that the information of said transducer is given in form of an electrical variable signal as a function of the heat exchange pressure conditions in said circuit downstream of the coil.
Cooling unit according to claim 5, characterized in that said transducer is placed downstream of said rapid attachment on the return pipe from said coil.
Cooling unit according to claim 1, characterized in that said refrigerating circuit is different from said second circuit and that said first and second heat exchange fluids are different each other, said first and second circuits being not communicating each other and being thermally coupled by a heat exchanger.
Cooling unit according to claim 9, characterized in that the thermal coupling between said circuits if effected in countercurrent.
Cooling unit according to claim 9, characterized in that said first heat exchange fluid, circulating in said refrigerating circuit, is a freon containing refrigerating fluid and that said second heat exchange fluid, circulating in said second circuit, is a liquid heat exchange fluid having a low freezing point and a high boiling point.
Cooling unit according to claim 9, characterized in that said first circuit is a closed refrigerating circuit and that said second circuit comprises a pump for the second heat exchange fluid circulation, a tank for the recovery of said second heat exchange fluid, a refrigerating plate consisting of said coil, a pair of connecting joints placed respectively upstream of the inlet pipe and downstream of the outlet pipe of the heat exchange fluid in said coil to allow said coil detachment from, or connection with the remaining part of said second circuit, as well as a pipe in a situation of heat exchange with the evaporator of the refrigerating circuit.
Cooling unit according to claim 12, characterized in that said pump is a positive-displacement pump.
Cooling unit according to claim 9, characterized in that said means to stop said heat exchange fluid circulation comprise at least a three-way valve placed upstream of the of said pump, two ways being connected with the circuit, the third way being connected with the exterior to allow to allow air to be pumped into the circuit and the consequent emptying of said second fluid from the coil.
Cooling unit according to claim 14, characterized in that said actuating means comprise a control device capable to switch said three-way valve placed on the delivery pipe toward said coil and to actuate the switching-on of said pump, as well as a sensor suitable to actuate the switch off said pump after a predetermined value of the coil emptying is reached.
Cooling unit according to claim 15, characterized in that said control device is of electromechanical or electric type and that said three-way valve is a electrically actuated solenoid valve.