EP0061104B1

EP0061104B1 - Device for the adjustment of the refrigerating fluid flow in a apparatus for the production of cold or hot conditions and system for regulating such fluid flow

Info

Publication number: EP0061104B1
Application number: EP82102038A
Authority: EP
Inventors: Luigi Alluto
Original assignee: Indesit Industria Elettrodomestici Italiana SpA
Current assignee: Whirlpool EMEA SpA
Priority date: 1981-03-24
Filing date: 1982-03-13
Publication date: 1986-09-10
Also published as: EP0061104A3; EP0061104A2; DE3273098D1

Description

The present invention refers to a device for the adjustment of the refrigerating fluid flow in an apparatus for the production of cold or hot conditions, and to its application in a regulating system of the refrigerating fluid in a refrigerator comprising at least two cooling cells at different temperatures, each of which is cooled through an evaporator through which the refrigerating fluid is flowing, one of the said cells being meant for fresh food, whilst the other is for frozen food, a compressor for compressing the refrigerating fluid, a condenser for condensing the refrigerating fluid coming from the compressor and capillary tubes for carrying of the refrigerating fluid from the condenser to the evaporators.
It is known that in refrigerating circuits of household appliances the expansion valve was replaced by a capillary device, out of practical and money sparing reasons.
This capillary device evidences however some weak sides, which are essentially due to its scarce flexibility and adaptability to the different load conditions and to the different ambient temperature. As a matter of fact under light loads or with high ambient temperatures, it is possible that by outflowing from the evaporator there could still be some refrigerating fluid in liquid conditions; this determines a considerable lowering of the refrigerator's performance and also the building up of hoarfrost on the backflow piping of the refrigerating flow returning to the compressor; it could even occur that some liquid penetrates into the compressor, damaging it.
Under heavy load conditions, or when ambient temperature is low, it is possible on the contrary that in the last portion of the evaporator there remains some refrigerating fluid as saturated steam with a limited cooling power. Under such conditions there would be an insufficient cooling of the cell to be cooled. Furthermore the two doors refrigerators equipped with two cooling rooms, one for fresh foods and one for frozen ones (cell freezer) with a single compressor and only one refrigerating fluid circuit, raise the problem that by regulating temperature in one of the two cells, temperature changes also in the other cell, automatically. This link creates problems when for instance one must lower the temperature in the freezer cell (because some fresh food was introduced and is to be frozen), whilst the temperature in the fresh food cell is on desired level and is not to be further lowered. In such cases it would be very appropriate to be able to adjust the refrigerating fluid flow. To this end one could use either an expansion valve (replacing the capillary tube) or an electro-magnetic valve. However the expansion valves require a rather careful machining and are obtainable at high costs.
In fact, they give problems when assembled to the refrigerator, and they have to be provided with pipe fittings for the connection (or eventual disconnection in repairing operations), because it is very expensive (for the special equipment needed) to provide the welding of said expansion valve in the manufacturing stage of the refrigerator, for the delicacy of the valve. If one would directly assemble said valve to the refrigerator in its manufacturing stage, the valve should be disassembled for the welding to the parts of the refrigerator and further reassembled after the welding operation is performed, otherwise it should be provided a suitable cooling equipment.
The electro-magnetic valves instead could be inserted and connected in series to the refrigerating circuit as shown in U.S.A. Patent No. 2.791.099 which describes a throttling device for refrigerating fluid for a refrigerating circuit comprising a first and a second part of a tube and an element for the regulation of the flow of the refrigerating fluid connected between the two parts, the regulation element is substantially made of hollow cylinder presenting two ends to which are connected the two ends of the tube, said cylinder containing a partition presenting an orifice that determines the maximum flow of fluid through the regulation element and a movable element which is subject to a magnetic field produced by a coil that may be flowed by electric current, whose position in respect of the partition determines the quantity of refrigerating fluid passing through the regulation element; or on a branch line parallel to the evaporator (as shown in U.K. Patent Application No. 2.016.128), in this last case regulation should occur through opening for a necessary lapse of time the valve (normally closed) in order to "short" the evaporator, which under such conditions would no longer cool the cell. But in this case it would be necessary to supply the refrigerating circuit with an additional branch, thus increasing production costs.
Considering that the two evaporators can be connected in series or in parallel, an independent functioning of the two cells can be obtained through two-three or four-way valves of the electromagnetic kind, connected in the refrigerating circuit and allowing the passing through, the stopping or the deviation of the refrigerating fluid in the two evaporators (as shown in British patent No. 1.406.883 or French patent application No. 2.392.303).
For instance by blocking the flowing of the refrigerating fluid into the evaporator of the fresh foods cell, it is possible to defrost said cell and to freeze the frozen foods cell alone. Such electro- magnetic valves involve, however a relatively higher cost than the cost of simple electro- magnetic valves with a single input and output.
Another drawback in the refrigerators mentioned above after the stopping of the compressor (i.e. during the equalization of the refrigerating fluid pressures) is due to the fact that such fluid during its transfer from the condenser to the evaporator conveys external heat and thus raises the temperature of the evaporators, degrading them in consequence.
Finally in U.S. patent No. 3 786 648 it is shown a refrigerator with two evaporators connected in parallel, each of which being associated to a capillary tube upstream of which is placed a respective electro-mechanical valve which controls the operation of its associated evaporator.
The present invention aimsto realize a device for the regulation of the fluid flow in a refrigerating circuit at a very low cost, and which could replace the expansion valve or the capillary device for the purpose of throttling, without having their disadvantages, and which in case of damage to the electrical component of the device (coil) this can be easily replaced without cutting the circuit of the refrigerating fluid.
To reach these purposes the present invention proposes a refrigerating circuit comprising a first and a second part of a capillary tube and a device for the regulation of the flow of the refrigerating fluid connected between the two parts, the regulation device being substantially made of hollow container consisting of a single body, presenting two slender ends in one end of which is inserted an end of the first part of the capillary tube and in the other an end of the second part of the capillary tube, said container containing a partition presenting an orifice that determines the maximum fluid flowthrough the regulation device and a controlled movable element whose position in respect of the partition is controlled by a magnetic field produced by a coil and by the pressure of the fluid inside said capillary tube and determines the quantity of refrigerating fluid passing through the regulation device, characterized in that said coil is placed around said regulation device and is supported by a spool having a diameter greater than said container, so that during the use the coil is mounted around the container and around a part of said capillary tube at least which is folded next to said container, so that the spool can be removed from the group formed by the container and by the folded part of the capillary tube for permitting a replacement of the coil in case of damage, without having to cut the circuit of the refrigerating fluid.
Furthermore, the invention also concerns an apparatus for the production of heat or cold conditions and a system for the adjustment of the refrigerating fluid flow in a refrigerating device, comprising such a refrigerating circuit.
Further scopes and advantages of the present invention will appear clearly from the detailed description hereinafter drawn up and the enclosed drawings, which are to be understood purely as examples without any specific limitation.
We have here three figures in which:

In the figure 1 appears a cross section of the first realization of a regulating device forming part of the circuit according to the present invention; in the figure 2 appears schematically a refrigerator arranged according to the regulating system of the refrigerating fluid subject of the present invention and applying the device mentioned before and appearing on figure 1; and in the figure 3 there appears a cross section of a second form of realization of the device covered by the present invention.

With reference to figure 1 a cylindrical copper container 11 is shown, with two apertures 12 and 14 opened in its end portions. In the lower aperture 12 a first part 13' of a capillary tube 13 is inserted and welded, from which the refrigerating fluid flows into the evaporator. In the upper aperture 14 a second part 15 of the same capillary tube 13 is inserted and welded; it is bent so as to adhere to the container 11 and to remain parallel to the first part 13' of the capillary tube; from this part 15 arrives the refrigerating fluid proceeding from the condenser. Around the lower portion of the container 11 and of the capillary tube portion 15 a coil 16 is arranged, supported by a spool 21 and fed by a continuous electric voltage. Inside the container 11, and in its lower portion, there is a circular partition 17 with a hole 18 having a cylindrical shape, whilst in the upper part of the container there is an iron core 19 with a tip 20 in its lower part, having an adequate size for occluding the hole 18. The feeding of the coil 16 could also occur through a.c., but in consideration of the factthat all the outer coating is a copper one, an a.c. feeding would generate induced currents which would cause losses. Furthermore the functioning would be very noisy.
In rest conditions, when no current circulates inside the coil 16, the iron core 19 and its bit 20 occlude completely the hole 18 due to their weight and especially to the pressure of some atmospheres of the refrigerating fluid arriving from the condenser which press them downwards: in this way the electric valve remains closed and refrigerating fluid is not flowing through.
When coil 16 receives electric current, a magnetic flux is generated which in turn generates a force which attracts the iron core 19 and its bit 20 upwards, against the resistance of the pressure of the refrigerating fluid arriving from the condenser and tending to thrust such components downwards: however the attraction strength in upward direction is such that it overcomes such resistance and the final effect is an upward movement of the components mentioned above, so that they no longer obstruct the hole 18. It is to be noted that the sustentation of the core 19 by the magnetic attraction of the coil 16 is made easier through the fact that the device is inserted by cutting through the capillary tube so that same produces a decrease in the pressure exerted on the core 19 by the flow of refrigerating fluid. Furthermore when core 19 is completely lifted, the entire inner part of the container 11 is essentially under the same pressure. In this way the electrovalve is open and the refrigerating fluid can flowthrough. When the coil 16 is de-energized, bit 20 falls down but the pressure force of the fluid keeps it compressed against the hole 18 so that the electrovalve is maintained closed. With the above described device appearing on figure 1, one obtains therefore a regulation called "digital" for the refrigerating fluid, because in consequence of control current reaching coil 16 and obviously in dependence on the pressure of the refrigerating fluid, the electrovalve remains open or closed. A continuous regulation of the refrigerating fluid flow, according to a system called "analogue", can be obtained by using the device appearing on figure 3, slightly different from that of figure 1, where parts of capillary tubes 13' and 15 are exchanged in respect of the end connections with the container 11. Part 15 through which arrives the fluid proceeding from the condenser is welded to the lower aperture of the container 11, whilst the part 13' through which fluid flows to the evaporator is welded to the upper aperture of the container 11. Moreover the coils 16 is arranged around the lower area of the container 11 and the hole 18'cut into the circular partition 17 assumestheform of a truncated conewhilstthe bit 20 of the core 19 is adequately made of nylon. In this case, and in rest conditions, when no current passes through the coil 16, the iron core 19 and its bit 20 should close due to their weight the hole 18', but the pressure of the refrigerating fluid counterbalances the said weight, so that they assume a position which allows the flowing through of all the refrigerating fluid, thus permitting to obtain the maximum flow designed for the capillarytube.
When a determined quantity of current passes through the coil 16 an appropriate magnetic flux is generated which in turn generates a force attracting the iron core 19 and its bit 20, which occludes partially the hole 18',thus reducing the flow of the refrigerating fluid to a certain extent.
The displacement of the iron core 19 and of its bit 20, and therefore the size of the occlusion of the hole 18' are a function of the quantity of current circulating through the coil 16, so that by varying continuously such a current, one can vary with the same precision said aperture of hole 18'. In dependence on the size of the capillary tube 13 and of the capillary tube 13 and on the opening of said hole 18' one can obtain an exact regulation of the flow of the refrigerating fluid which never lowers to nought due to the considerable contrary force exerted by the refrigerating fluid in regard to the core 19 against which the flow is striking.
It is furtherto be noted thatthe different shape of the two holes (18 is cylindrical and 18' hasthe form of a truncated cone) has its importance, because the shape of a truncated cone although useful in the instance of the figure 3 for an "analogue" regulation of the flow, is no longer applicable in the case of figure 1 for a "digital" regulation of same, in view of the fact that the surface between bit 20 and hole 18 would be then so large, that extremely strong currents should be fed to the coil 16 to obtain a disjunction between such two components. It is therefore useful to have in this case a small contact surface between such components through a cylindrical hole 18.
One can also note that the part of capillary tube which is bent on the side of the container 11 allows an easy replacement of the coil 16 (figure 1 and 3): as a matter of fact should said coil 16 be damaged for a whatsoever reason and be therefore replaced, it would be sufficient to extract it from its position, with a relative axial movement between the copper container 11 and capillary tube 13 and the spool 21 without having to cut and to disturb in the slightest the refrigerating fluid circuit.
With reference to figures 2 we can observe: a compressor 1, a condenser 2 connected to the outlet of compressor 1, a dehydrating strainer for the refrigerating fluid 3 on the outlet of the condenser 2, a first capillary tube 4F (diameter 0.70 mm, length 2800 mm) connected with the dehydrating strainer 3, a first electrovalve with a removable coil 5F (like that on figure 1), inserted into the first capillary tube 4F which is appropriately interrupted, a first evaporator 6F connected with the capillary tube 4F, a second capillary tube 4C (diameter 0.70 mm, length 3200 mm) connected with the dehydrating strainer 3, a second electrovalve with removable coil 5C, just as on figure 1, inserted into the second capillarytube 4C, appropriately interrupted, a second evaporator 6C, the inlet of which is connected with the outlet of the first evaporator 6F and the second capillary tube 4C, and a return conduit 7 connecting the outlet of the second evaporator 6C with the input of the compressor 1.
The functioning of the refrigerating assembly is carried out by a thermostatic circuit which does not appear on figure and is as follows: when both cells require cold, the compressor 1 starts to function, the electrovalve 5F remains open, the electrovalve 5C is closed. In this way the refrigerating fluid can circulate in both evaporators 6F and 6C and is cooling both cells.
When only one cell (that for frozen food) needs cold, compressor 1 is always in operation, while the electrovalve 5F is closed and the electrovalve 5C is open. In this way no refrigerating fluid is circulating in the evaporator 6F and the fresh food cell is not cooled, while the circulation of refrigerating fluid in the evaporator 6C cools the cell containing frozen food. Immediately after the stopping of the compressor 1, the thermostatic circuit opens both electrovalves 5F and 5C and allows a quick re-balancing of the pressures of refrigerating fluid, thus avoiding the degrading of the evaporators 6F and 6C.
In a variant, said thermostatic circuit can open the first electrovalve 5F and close the second one 5C; in this way the re-balancing of the pressures of the refrigerating fluid is not occurring very rapidly, but the whole of the outer heat is scattered on the evaporator of the cell forfresh food 6F, which is not worsening the operation because it finds itself in a phase of defrosting.
In this way, as can be noted, it was possible to obtain an essentially independent functioning of the two cells used for cooling purposes and the drawbacks connected with the degrading of the evaporators were avoided.
In a non appearing variant for the refrigerating circuit of the figure 2, the capillary tube 4C and the electrovalve 5C can be missing so that there remains only the capillary tube 4F ( forthe cells 6F and 6C connected in series) with an appropriate size and in which electrovalve 5F is inserted (its type being the same of that appearing on figure 3): the regulation in this case is of the "analogue" kind.
When both cells 6F and 6C are to be cooled, the electrovalve 5F finds itself in the maximum opening conditions and the flow of refrigerating fluid is at a maximum level with an efficiency able to cool both cells.
When the fresh food cell (in connection with evaporator 6C) does not need any cooling, but this is the case of the frozen food cell (connected with evaporator 6F) one uses the electrovalve 5F, in the way already described in reference to figure 3, in order to reduce the refrigerating fluid flow to a desired level, so that on the inlet of the evaporator 6C there remains essentially a saturated steam, practically deprived of any cooling power. In this way it is possible to cool the frozen food cell and not the fresh food one, thus obtaining an essentially independent functioning of the two cooling cells.
The above specification shows clearly the advantages presented by the device of the present invention, which comprises two portions of a capillary tube between which is connected in series an element, having a specific configuration, for the regulation of the flow of the refrigerating fluid and which realizes the function of a throttling device without the disadvantages of the expansion valve or the capillary device, and allows to easily replace the coil 16 of said device without cutting and causing any damage to the circuit of the refrigerating fluid.
Other advantages derive from the fact that both cells can practically be regulated independently for cooling purposes, that drawbacks connected with degrading of evaporators are eliminated, that the electrovalves have essentially the same performance of other known types which are more costly and finally that the functioning causes little noise.
It is obvious that numerous variations are possible as far as the regulation system of the refrigerating fluid is concerned; e.g. a different way of opening and closing the electrovalves or the shape and/or the materials used for the coating or the partition or the ferromagnetic core of said electrovalves, without leaving the basic principles included in the area of the invention.

Claims

1. Refrigerating circuit comprising a first (13') and a second (15) part of a capillary tube (13) and a device (11, 17, 19) for the regulation of the flow of the refrigerating fluid connected between the two parts (13', 15), the regulation device (11, 17, 19) being substantially made of hollow container (11) consisting of a single body, presenting two slender ends (12, 14) in one end of which is inserted an end of the first part (13') of the capillary tube (13) and in the other (14) an end of the second part (15) of the capillary tube (13), said container (11) containing a partition (17) presenting an orifice (18) that determines the maximum fluid flow through the regulation device (11, 17,19) and a controlled movable element (19) whose position in respect of the partition (17) is controlled by a magnetic field produced by a coil (16) and by the pressure of the fluid inside said capillary tube (13) and determines the quantity of refrigerating fluid passing through the regulation device (11,17,19), characterized in that said coil (16) is placed around said regulation device (11,17,19) and is supported by a spool (21) having a diameter greater than said container (11), so that during the use the coil (16) is mounted around the container (11) and around a part of said capillary tube (13) at least which is folded next to said container (11), so that the spool (21) can be removed from the group formed by the container (11) and by the folded part of the capillary tube (13) for permitting a replacement of the coil (16) in case of damage, without having to cut the circuit of the refrigerating fluid.

2. Refrigerating circuit according to claim 1, characterized in that said movable element (19) presents a terminal (20) of nylon.

3. Refrigerating circuit according to claim 1, characterized in that said orifice (18) has the shape of a truncated cone in order to permit an analogue regulation of the flow of the refrigerating fluid inside the regulation device (11, 17, 19).

4. Refrigerating circuit according to claim 1, characterized in that said orifice (18) has cylindrical shape in order to permit a regulation of the flow of the refrigerating fluid inside the regulation device (11, 17, 19) of the digital type.

5. Refrigerating circuit according to claim 3, characterized in that said movable element (19) moves vertically and that said regulation device (11,17,19) is connected to said capillary tube (13) and to the refrigerating circuit so that, without controlling said coil (16), the movable element (19) is subjected to the action of the flow of the refrigerating fluid that, in contrast to the weight of the movable element (19), keeps in opening position the regulation device (11, 17, 19), whereas when the electric current is made flow in the coil (16) a displacement of the movable element (19) takes place i.e. it reduces the flow of the refrigerating fluid through the regulation device (11, 17, 19).

6. Refrigerating circuit according to claim 4, characterized in that said movable element (19) moves vertically and that said regulation device (11, 17, 19) is connected to said capillary tube (13) and to the refrigerating circuit so that, without controlling said coil (16), the movable element (19) is subjected to the action of its weight and of the flow of the refrigerating fluid, so as to keep in closure position the regulation device (11, 17, 19), whereas when the electric current is made flow in the coil (16) a displacement of the movable element (19) takes place i.e. it makes result open the regulation device (11, 17, 19).

7. Apparatus for the production of heat or cold conditions, characterized in that it comprises a refrigerating circuit according to one of the preceding claims from 1 to 6.

8. System for the adjustment of the refrigerating fluid flow in a refrigerating device comprising at least two cooling cells at different temperatures, each of them being cooled through an evaporator through which flows the refrigerating fluid, one of the said cells being meant for fresh foods, whilst the other is for frozen foods, a compressor (1) for compressing the refrigerating fluid, a condenser (2) for condensing the refrigerating fluid coming from the compressor (1), and capillary tubes (4C, 4F) for carrying the refrigerating fluid from the condenser (2) to the evaporators (6C, 6F), characterized in that it comprises an arrangement of capillary tube (13), regulation device (11, 17, 19), and coil (16) as claimed in any one of the preceding claims 1 to 6 at leastfor one of the connections from the condenser (2) to the evaporators (6C, 6F), and thermostatic control means which warrant a substantially independent functioning of the two cooling cells.