REFRIGERATOR

Abstract

In a refrigerator having a thermally insulating housing which surrounds a storage chamber and having a refrigerant circuit which comprises a compressor, a condenser, a restrictor and an evaporator which cools the storage chamber, the restrictor is arranged at least partially on a side wall of the housing.

Description

The present invention relates to a refrigerator, in particular a household refrigerator, having a thermally insulating housing, which encloses a storage chamber for items to be chilled, and a refrigerant circuit, which comprises a compressor, a condenser, a restrictor and an evaporator, which cools the storage chamber. The action of such a known refrigerator is based on the fact that the compressor sucks refrigerant in vapor form out of the evaporator and feeds the refrigerant, when it has been heated adiabatically by compression, to the condenser, where it condenses while emitting heat. The liquid refrigerant thus obtained decompresses as it passes through the restrictor and returns to the evaporator adiabatically cooled.

The extent of adiabatic cooling is a function of the pressure difference passed through between condenser and evaporator. The warmer the refrigerant at the outlet of the condenser, the warmer it also is when it reaches the evaporator after decompressing. Theoretically it is possible to approximate the temperature of the refrigerant at the outlet of the condenser to anywhere near the temperature of the environment, to which the condenser emits its heat but the required dimensions of the condenser have to be greater, the smaller this temperature difference is to be. The cooling that can be achieved at the condenser is also limited by parasitic heat transfer between warm, upstream regions of the condenser and cooler downstream regions. When air, which has already been heated in upstream regions of the condenser, flows around a downstream region of the condenser, said downstream region can no longer cool the refrigerant to below the temperature of said air.

Refrigerators are known, in which a frame heater is provided to prevent condensation on the housing in the vicinity of a seal positioned between carcass and door of the housing. Such a frame heater comprises a tube, which is inserted into the refrigerant circuit between compressor and condenser or downstream of the condenser, in order to heat the surfaces of the housing that are susceptible to condensation to above dew point with the compression heat of the refrigerant. As the susceptibility to condensation stems from the thermal coupling of said surfaces to the cooled storage chamber, the heat released by the frame heater ultimately also flows into the storage chamber to a significant extent, thereby having a detrimental effect on the energy efficiency of the refrigerator.

The object of the present invention is to improve the energy efficiency of a refrigerator, in particular a household appliance.

The object is achieved in that with a refrigerator of the type defined in the introduction the restrictor is disposed at least partially on a side wall of the housing. Because of its small free cross section compared with other regions of the refrigerant circuit, the restrictor contributes little to the volume of the refrigerant circuit and therefore does not increase the quantity of refrigerant required to operate the refrigerant circuit to any appreciable degree. Being disposed on the side wall, the restrictor is protected from waste heat, which is released by the condenser, which is generally disposed on the rear of the appliance. The side wall is therefore a relatively cool region of the refrigerator housing and allows efficient additional cooling of the refrigerant circulating through the restrictor.

The restrictor is preferably disposed in the side wall between an outer skin and an insulating layer of the same in such a manner that it is protected and not visible from the outside. In order to be able to absorb and pass on the heat from the restrictor quickly, the outer skin of the side wall is preferably metallic.

The restrictor is preferably bonded to the outer skin, to ensure that it remains in heat-conducting contact with the outer skin when the insulating layer is applied during assembly of the refrigerator. The insulating layer is preferably produced in the technically standard manner by allowing synthetic resin foam to expand in a hollow space in the housing delimited by the outer skin.

Fast and simple bonding of the restrictor and outer skin can be achieved with the aid of adhesive tape.

In order to prevent heat being introduced into the evaporator by way of the restrictor, preferably only an upstream segment of the restrictor is disposed on the side wall.

A downstream segment of the restrictor can be positioned in the known manner instead in a suction tube leading from the evaporator to the compressor.

In order to keep the pressure drop in the refrigerant small, at least in the upstream segment of the restrictor, this latter preferably has a larger cross section than the downstream segment. As this upstream segment should not increase the volume of the refrigerant circuit significantly, it is preferable for the upstream segment to have a free diameter of less than 1 millimeter.

In order to allow efficient cooling of the refrigerant between its exit from the condenser and entry into the evaporator, the upstream segment preferably has a length of at least 1 meter. In practice the length of the upstream segment will be up to 2 meters in a household refrigerator of standard size.

For assembly of the refrigerator it is expedient if the downstream segment and the upstream segment of the condenser are joined to one another outside an insulating layer of the side wall.

The refrigerant circuit preferably has a dryer, the refrigerant supply line of which is connected to the upstream end of the restrictor on the side wall for flow purposes.

Further features and advantages of the invention will emerge from the description which follows of exemplary embodiments with reference to the accompanying figures, in which:

FIG. 1 shows a perspective view of an inventive household refrigerator from the front; FIG. 2 shows a perspective view of the refrigerator from the rear; FIG. 3 shows a plan view of a section of sheet with a restrictor segment fastened thereto, which forms an outer skin of a side wall of the refrigerator; and

FIG. 4 shows a diagram of the refrigerant circuit of the refrigerator.

FIGS. 1 and 2 show perspective views of a counter-height household refrigerator 1. A thermally insulating housing of the appliance is made up of an essentially cuboid carcass 2 and a door 3, which together delimit a storage chamber 4. The carcass 2 has a structure that is known per se, with a plastic deep-drawn inner container 5, an outer skin joined together from a number of elements and a polyurethane foam insulating layer filling an intermediate space between the inner container 5 and the outer skin. The elements of the outer skin include two sheet sections 6, which extend in each instance over a side wall of the carcass 2 and are connected to the inner container 5 at a front frame 7 of the carcass 2 facing the door 3.

A machine chamber 8 is cut out at the rear of the carcass 2 close to the bottom and holds a refrigerant compressor 9. A condenser 10 is connected to a pressure connector of the compressor 9. The condenser 10 is shown in FIG. 2 as a wire tube heat exchanger mounted on a rear wall of the carcass 2 above the machine chamber 8 but other models of the condenser 10, in particular as a compact finned tube heat exchanger also accommodated in the machine chamber 8 and force-cooled by a fan, are also possible. A downstream connector of the condenser 10 is connected by way of a sleeve 11 to a restrictor tube 12, which extends in a looped manner on the inside of one of the sheet sections 6 facing the insulating layer.

The sleeves 11, 16 allow the appliance 1 to be assembled, in that, before the sheet sections 6 are joined to the inner container, the restrictor 12 is fastened to one of the sheet sections 6, the carcass 2 is joined together so that the ends of the restrictor 12 are exposed in the machine chamber 8 and the carcass is then foamed and finally the restrictor 12 is inserted into the refrigerant circuit with the aid of the sleeves 11, 16.

FIG. 3 shows a perspective view of the inside of the sheet section 6 with the restrictor tube 12. The section 6 comprises a flat central plate 13, which is provided to form the outer skin of a side wall of the carcass 2 and to which the restrictor tube 12 is fastened with the aid of adhesive tape strips 14. Webs 15 angled away from the central plate 13 extend in the finished appliance 1 to its front frame 7 or its rear and are connected there to the inner container 5 or a rear wall plate (not shown) in a foam-tight manner.

Again with reference to FIG. 1 a second sleeve 16 disposed in the machine chamber 8 connects the restrictor tube 12 to a second, narrower restrictor tube 17, which traverses the insulating layer of the carcass 2 to ensure that the evaporator 18 is disposed in close thermal contact with the storage chamber 4. As shown schematically in FIG. 4, the restrictor tube 17 passes directly along the surface of a suction tube 19, which passes from the evaporator 18 to the compressor 9, or within said suction tube 19.

Because a tube with a small internal diameter, typically approx 0.8 millimeters, is used for the restrictor tube 12, the volume of the refrigerant circuit as a whole changes little—despite the restrictor tube 12 being typically 1 to 2 meters long—compared with a conventional refrigerant circuit of a refrigerator of the same size and therefore the quantity of circulating refrigerant required for efficient operation also changes little. As the restrictor tube 12 runs along the central plate 13 at a distance from the web 15 connected to the inner container 5, the flow of heat from the restrictor tube 12 to the storage chamber 4 by way of the connection between sheet section 6 and inner container 5 is negligible. The restrictor tube 12 is shielded from heat emitted from the condenser 10 by its spatial distance from the condenser 10. Therefore it is possible to achieve more efficient cooling of the refrigerant with the restrictor tube 12 than by enlarging the condenser 10 by the volume of the restrictor tube 12.

The appliance 1 is preferably positioned in such a manner that the side wall containing the restrictor tube 12 is exposed so that heat emitted from the restrictor tube 12 can be passed quickly to the environment. The invention can however also be used—if only with little scope—in a refrigerator with a concealed side wall, for example a built-in appliance or a counter-height appliance flanked at the sides by other objects. The sheet section 6 here operates as a thermal storage unit, which absorbs heat from the restrictor tube 12 while the compressor 9 is operational and drives refrigerant circulation. In a subsequent stoppage phase of the compressor the heat of the sheet section 6 can also be distributed to the environment with such a refrigerator.

Claims

1. A refrigerator, in particular a household refrigerator, having a thermally insulating housing (2, 3), which encloses a storage chamber (4), and a refrigerant circuit, which comprises a compressor (9), a condenser (10), a restrictor (12, 17) and an evaporator (18), which cools the storage chamber (4), characterized in that the restrictor (12, 17) is disposed at least partially on a side wall of the housing (2).

2. The refrigerator as claimed in claim 1, characterized in that the restrictor (12, 17) is disposed on the side wall between an outer skin (6) and an insulating layer of the side wall.

3. The refrigerator as claimed in claim 2, characterized in that the restrictor (12, 17) is bonded to the outer skin (6), in particular by adhesive tape (14).

4. The refrigerator as claimed in one of the preceding claims, characterized in that the restrictor (12, 17) comprises an upstream segment (12) and a downstream segment (17) and the part of the restrictor disposed on the side wall is the upstream segment (12).

5. The refrigerator as claimed in claim 4, characterized in that the downstream segment of the restrictor (12, 17) is positioned in a suction tube (19) leading from the evaporator (18) to the compressor (8).

6. The refrigerator as claimed in claim 4 or 5, characterized in that the downstream segment (17) has a smaller cross section than the upstream segment (12).

7. The refrigerator as claimed in one of claims 4 to 6, characterized in that the upstream segment (12) has a free diameter of less than 1 mm.

8. The refrigerator as claimed in one of claims 4 to 7, characterized in that the upstream segment (12) has a length of at least 1 m.

9. The refrigerator as claimed in one of claims 4 to 8, characterized in that the downstream (17) segment and the upstream segment (12) are joined to one another outside an insulating layer of the side wall.