EP2743618A1

EP2743618A1 - Refrigerator for foods

Info

Publication number: EP2743618A1
Application number: EP12197386.1A
Authority: EP
Inventors: Augusto Buosi; Diego Modolo; Marco Beni
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2012-12-17
Filing date: 2012-12-17
Publication date: 2014-06-18
Anticipated expiration: 2032-12-17
Also published as: EP2743618B1

Abstract

A food refrigerator comprises a cabinet (105), a heat pump for submitting a refrigerant fluid to a thermodynamic cycle, wherein the heat pump comprises a refrigerant condenser (135) mounted on a back wall (120) of the cabinet and extending along said back wall, and a forced air ventilation system (140) for ventilating the condenser. The forced air ventilation system comprises at least one blower (305) for drawing in air from the outside environment, and an air conveyor (205) associated with the at least one blower for directing the ambient air drawn in and propelled by the at least one blower towards the refrigerant condenser.

Description

Background of the invention

Field of the invention

The present invention relates to appliances for food preservation, such as food refrigerators, particularly, although not limitatively, for domestic use.

Overview of the related art

Food refrigerators essentially consist of a thermally-insulated compartment for the storage of food, and a heat pump that transfers heat from the inside of the refrigerator to its external environment so that the inside of the refrigerator is cooled to a temperature below the ambient temperature of the room (e.g., kitchen) where the appliance is located.
In the heat pump, a refrigerant fluid undergoes a thermodynamic cycle. The refrigerant enters a compressor as low-pressure vapor at or slightly above the temperature of the refrigerator interior. In the compressor, the vapor is compressed and exits the compressor as high-pressure superheated vapor. The superheated vapor flows under pressure through coils or tubes forming a condenser, which are cooled by exposure to air in the room. The condenser cools the vapor, which condenses (liquefies). As the refrigerant leaves the condenser, it is still under pressure but only slightly above room temperature. The liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve, to an area of much lower pressure. The sudden decrease in pressure results in a flash evaporation of part of the liquid. The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as auto-refrigeration. This cold and partially vaporized refrigerant continues through the coils or tubes of an evaporator unit. The food storage compartment is in heat-exchange relationship with the evaporator; in the evaporator, the refrigerant completely vaporizes, drawing further latent heat from the compartment, which is thereby kept cold. The refrigerant leaves the evaporator, fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle.
In household (domestic) refrigerators, two classes of refrigerant condensers are mainly used: static condensers or dynamic condensers.
Static condensers comprise external heat exchangers extending essentially along the whole vertical length of the food storage compartment at the rear of the refrigerator cabinet (i.e., opposite to the front door), or skin condensers attached to the cabinet side walls. Static condensers are cooled by a natural (non-forced) flow of ambient air that flows by convection from the bottom to the top of the refrigerator cabinet.
Dynamic condensers are usually box-shaped and placed in a recess at the bottom of the refrigerator cabinet where the compressor is also accommodated, or in a "worm module" under the cabinet. Dynamic condensers are cooled by a forced flow of ambient air, taken in by means of a fan. Examples of refrigerators with dynamic condensers are given in DE 19933603 , US 3,785,168 , US 2,079,770 , EP 1919973 .
Refrigerators are often fully embedded (built-in or encased) in the furniture of the kitchen, and this makes the ventilation (natural or forced) of the condensers more difficult.
In refrigerators with dynamic condensers the path of ambient air cooling the condenser is typically "U"-shaped: ambient air is taken in through an opening at the bottom of the front of the kitchen furniture, caused to flow through the condenser, and expelled through another opening, which can also be at the bottom of the front of the kitchen furniture.
US 1,769,119 discloses a condensing system for household refrigerator using means for augmenting the draft passing over the compressor and condenser when the temperature of the environing atmosphere is such that the natural draft arrangement does not permit the refrigerating system to operate at its proper efficiency. A fan driven by a motor is provided, disposed in an apparatus compartment beneath the refrigerating chamber containing the compressor and its motor.

Summary of the invention

A proper ventilation of the condenser is important for cooling it down; a condenser that is not properly ventilated and cooled reduces the efficiency of the heat pump, and the refrigerator does not operate properly.
Especially for built-in refrigerators to be encased in the kitchen furniture, but also for free-standing refrigerators, the solutions known in the art do not appear satisfactory.
Refrigerators with dynamic condensers are useful in some specific applications (e.g., for so-called "under-top" refrigerators, intended to be encased in the kitchen furniture below the kitchen worktop: in this case there is no possibility for the ambient air to escape from the refrigerator top). However, the box-shaped condenser used in dynamic condenser refrigerators costs more than a condenser of the type used in static condenser refrigerators. Also, a condenser for a static condenser refrigerator has a great heat exchange surface (the condenser can occupy the large area at the back of the cabinet), beneficial to the refrigerant cooling down. Refrigerators with condensers of the type used in static condenser refrigerators are thus preferable in some circumstances, and they are also traditionally preferred in some regions of the world.
The Applicant has observed that the solution disclosed in US 1,769,119 does not work properly, especially in a built-in refrigerator, encased within the kitchen furniture. The apparatus compartment where the compressor is disposed, and where, according to US 1,769,119 , the fan is also disposed, is a closed compartment with very small openings at the bottom and the top. A free fan disposed in this compartment is not able to move air from the small apertures at the bottom and then to force the air up to the condenser, which is located out of the compartment, along the back of the refrigerator. In a built-in appliance a free fan positioned as described by US 1,769,119 is only able to recirculate air inside the compressor compartment; the compressor is still cooled by the natural air flow that moves by convection.
According to an embodiment of the present invention, a food refrigerator is provided, comprising a cabinet and a heat pump for submitting a refrigerant fluid to a thermodynamic cycle, wherein the heat pump comprises a refrigerant condenser mounted on a back wall of the cabinet and extending along said back wall.
The food refrigerator comprises a forced air ventilation system for ventilating the condenser. The forced air ventilation system comprises at least one blower for drawing in air from the outside environment, and an air conveyor associated with the at least one blower for directing the ambient air drawn in and propelled by the at least one blower towards the refrigerant condenser.
Advantageously, the at least one blower and the air conveyor are housed in a recess of the refrigerator cabinet at the bottom of the refrigerator cabinet, below the refrigerant condenser.
In an embodiment of the invention, the air conveyor may house the blower.
In an embodiment of the present invention, the air conveyor may comprise a first portion housing the blower, and a removable second portion configured to be mounted to the first portion for defining an air channel for the air expelled by the blower.
Preferably, the first and the second portions are configured so as to allow access to the blower when the second portion is removed.
In an embodiment of the present invention, the air conveyor may comprise a first portion housing the blower and at least part of a motor activating the blower, and a removable third portion configured to be mounted to the first portion to cover part of the motor.
Preferably, the first and the second portions are configured so as to allow access to the motor when the third portion is removed.
Advantageously, the air conveyor is provided with a plate for mounting it to a cross-plate at the bottom of a recess of the refrigerator cabinet where the air conveyor is housed.
The food refrigerator may advantageously comprise a control unit for selectively activating the blower.

Brief Description of the drawings

These and other features and advantages of the present invention will be made apparent by the following detailed description of an embodiment thereof. The description is provided merely by way of non-limiting example, and makes reference to the annexed drawings, wherein:

Figure 1 shows in isometric view from the back a refrigerator according to an embodiment of the present invention;
Figure 2 shows in enlarged scale a detail of the bottom of the refrigerator shown in Figure 1 ;
Figure 3 shows in exploded view a blower according to an embodiment of the present invention for the forced ventilation of the refrigerator condenser; and
Figure 4 is a schematic cross-sectional view illustrating the operation of the refrigerator of Figures 1 and 2 .

Detailed description of an embodiment of the invention

Referring to the drawings, in Figure 1 there is shown in isometric view from behind a refrigerator according to an embodiment of the present invention.
The refrigerator comprises a refrigerator cabinet 105, having two side walls (only one of which is visible, and is denoted 110), a top wall 115, a rear wall 120 and a bottom wall 415 (shown in Figure 4 ). Frontally, not visible in the drawing, the cabinet has an opening accessing the refrigerator inner compartment, where the food to be preserved can be stored, and a door, for closing the inner compartment opening.
The refrigerator comprises a heat pump having a refrigerant compressor, a refrigerant liquefier or condenser, a metering or throttling device, and a refrigerant evaporator, all in fluid communication by means of pipes. The compressor, denoted 125 in the drawing, is positioned in a recess 130 at the rear bottom of the cabinet 105. The condenser, denoted 135 in the drawing, is an essentially flat external heat exchanger, with a winding piping for the refrigerant fluid, that is mounted onto the cabinet 105 (e.g. by means of brackets and screws) so as to extend along the cabinet rear wall 120, preferably along a significant length thereof, so as to feature a large heat exchange area. This is a typical arrangement for a static condenser (on the contrary, the refrigerators with dynamic condensers typically have box-shaped condensers that are relatively small in outer dimensions and are placed in the recess 130 where the compressor 125 is also placed).
In a refrigerator with a static condenser, ambient air usually flows by natural convection over the condenser 135, from the bottom to the top of the cabinet 105, exiting from an opening at the rear top of the cabinet. However, when the refrigerator is encased, built-in the kitchen furniture, the natural flow of ambient air over the condenser is difficult.
According to a preferred embodiment, the refrigerator of the present invention comprises an air ventilation system 140 for augmenting the draft of ambient air over the condenser 135.
Referring also to Figures 2 and 3 , the air ventilation system 140 advantageously comprises a fan or blower 305 and an air conveyor 205 conveying the air generated by the fan 305. In the preferred embodiment here described, the air conveyor 205 houses the fan 305. The fan 305 draws ambient air in from the outside environment (i.e., the kitchen) and the air conveyor 205 conveys the air taken in by the blower towards the condenser 135. Advantageously, the fan 305 and the associated air conveyor 205 are positioned in the recess 130, preferably aside the compressor 125, as visible in enlarged scale in Figure 2 .
Figure 3 shows in exploded view the exemplary constitution of the air ventilation system 140 according to an embodiment of the present invention.
The air conveyor 205 is advantageously provided with a fixing plate 315 for mounting it, by means of screws or bolts, onto a cross-plate 210 at the bottom of the recess 130 (to which the compressor 125 is also mounted). The fan 305 is preferably driven by an own motor 320 with horizontal axis, preferably coupled to the fan 305 through motor vibration absorbers 325, to damp vibrations. Preferably, the air conveyor 205 is mounted onto the cross-plate 210 by interposition of further vibration absorbers 335, e.g. made of rubber, for further dumping vibrations.
Preferably, as shown in Figure 4 , the air conveyor 205 defines an air conveying duct or channel 406 for conveying the air blown by the fan 305, and a motor chamber 407 housing the motor 320.
With reference to Figure 3 , the air conveyor 205 is preferably an assembly of three portions removably coupled to each other:

a main hollow body 340 housing the fan 305 and partly the motor 320,
a front cover 330, coupled to the main body 340 by means of screws and giving access to the motor 320 when removed, and
a back cover 345, coupled to the main body 340 by means of snap fits and giving access to the fan 305 when removed.

It is clear that other kind of coupling means can be used as well to couple the three portions.
The main hollow body 340 and the back cover 345 are shaped substantially as two half-shells to form together the air conveying duct 406 receiving and conveying the air blown by the fan 305.
In particular:

the main hollow body 340 has a lower cylindrical portion 340a with horizontal axis defining a chamber hosting the fan 305 and an upper vertical wall 340b extending upwards from the back end of the cylindrical portion 340a, and
the back cover 345 is a substantially planar body having a lower circular portion 345a matching with the perimeter of the cylindrical portion 340a of the main hollow body 340, and a vertical wall 345b extending upwards from the lower circular portion 345a and matching with the vertical wall 340b of the main hollow body 340.

Thus, as shown in Figure 4 , the air conveying duct 406 has a first horizontal section 406a (where the fan 305 is located) and a second vertical section 406b directed upwards.
The motor chamber 407 is formed by the front part of the main hollow body 340 and the front cover 330. The motor chamber 407 has, in its lower part, an opening defining an air inlet 409a for the air conveyor 205, to suck the air entering the recess 130 from the outside of the refrigerator cabinet 105. Moreover, the refrigerator cabinet 105 has, in its bottom, in particular between the bottom wall 415 and the cross-plate 210, an opening 420 to allow air to enter into the recess 130 from below the cabinet 105. As air is sucked from the outside, air circulation in the whole recess 130 is improved, so that also the compressor 125 is better cooled, thus increasing its efficiency.
Accordingly, the air conveyor 205 is adapted to convey the air taken in by the fan 305 towards the top of the refrigerator cabinet 105. An air outlet 409b of the air conveyor 205 is located just below the condenser 135.
Advantageously, hits absorbers 350 are attached to the outside of the back cover 345 for protecting the air conveyor 205 when the refrigerator 100 is installed in the kitchen, abutting the kitchen wall, and also dumps vibrations transmitted by the fan 305.
The operations of the refrigerator of the present invention will be herein below described with reference to the schematic cross-sectional view Figure 4 , illustrating the refrigerator encased in a kitchen furniture. In the drawing, 405 denotes the cross-sectioned walls of the kitchen furniture where the refrigerator is encased. When the refrigerator is encased in the kitchen furniture, an air gap 410 is left between the bottom wall 415 of the refrigerator cabinet 105 and a bottom wall 405-1 of the kitchen furniture 405. Similarly, an air gap 420 is left between the rear wall of the refrigerator cabinet 105 and the rear wall 405-2 of the kitchen furniture 405. When the kitchen furniture 405 does not have a rear wall, an air gap is similarly formed between the rear wall 120 of the refrigerator and the kitchen wall, laterally closed by the vertical side wall of the kitchen furniture where the refrigerator is encased.
Moreover, the refrigerator cabinet 105 has, in its bottom, in particular between the bottom wall 215 and the cross-plate 210, an opening 420 to allow air within the air gap 410 to enter into the recess 130.
When the fan 305 is operating, it draws in ambient air from the air gap 410 into the recess 130 through the opening 420, and then into the air conveyor 205 through the air inlet 409a, and thanks to the air conveyor 205 the air is then forced to flow up along the air gap 420, thereby ventilating and cooling the condenser 135. The ambient air, after having cooled the condenser 135, exits the air gap 420 and returns to the ambient through an opening provided at the top of the kitchen furniture wherein the refrigerator is encased.
If the refrigerator is not built-in but free-standing, the operations are exactly the same, and the walls 405-1 and 405-2 in Figure 4 could represent the floor and the wall of the kitchen against which the refrigerator is positioned. Even in the absence of a wall 405-2, the air conveyor 205 is able to properly direct the air blown by the fan 305 towards the condenser 135.
The solution according to the present invention is very flexible. It allows improving the efficiency of existing refrigerators with static condenser in a way that does not impact their design, by simply adding, if desired, the air ventilation system 140, which can be accommodated in the recess 130 at the bottom of the refrigerator cabinet where the compressor is placed. Thus, thanks to the solution of the present invention, a refrigerator with static condenser can easily be transformed into a refrigerator with forced-air condenser ventilation. This allows a manufacturer to have two distinct lines of product: one with static condenser ventilation and the other with forced condenser ventilation, but with a very small production cost (essentially just the cost of the fan 305 and associated air conveyor 205).
Advantageously, the refrigerator control unit can be configured to selectively activate the fan 305, for example in response to a user command. For example, the refrigerator control unit may be configured to cause the fan 305 to be activated only during the day and not at nighttime, so as to keep the noise level very low during the hours of sleep.
In the foregoing, an exemplary embodiment of the present invention has been described. Those skilled in the art will readily understand that several modifications to the described embodiments are possible. For example, in alternative embodiments the air conveyor can be a separate part with respect to the fan housing, coupled to the fan housing outlet so as to receive and guide towards the condenser the ambient air taken in by the fan. The fan, instead of being an axial fan as described above, can be a different type of fan, for example a centrifugal fan.

Claims

A food refrigerator comprising a cabinet (105), a heat pump for submitting a refrigerant fluid to a thermodynamic cycle, wherein the heat pump comprises a refrigerant condenser (135) mounted on a back wall (120) of the cabinet and extending along said back wall, and a forced air ventilation system (140) for ventilating the condenser, characterized in that the forced air ventilation system comprises at least one blower (305) for drawing in air from the outside environment, and an air conveyor (205) associated with the at least one blower for directing the ambient air drawn in and propelled by the at least one blower towards the refrigerant condenser.
The food refrigerator according to claim 1, wherein the at least one blower and the air conveyor are housed in a recess (130) of the refrigerator cabinet at the bottom of the refrigerator cabinet, below the refrigerant condenser.
The food refrigerator of claim 1 or 2, wherein the air conveyor houses the blower.
The food refrigerator of any of the preceding claims, wherein the air conveyor comprises a first portion (340) housing the blower, and a removable second portion (345) configured to be mounted to the first portion for defining an air channel for the air expelled by the blower.
The food refrigerator of claim 4, wherein the first and the second portions are configured so as to allow access to the blower when the second portion is removed.
The food refrigerator of any of the preceding claims, wherein the air conveyor comprises a first portion (340) housing the blower and at least part of a motor activating the blower, and a removable third portion (345) configured to be mounted to the first portion to cover part of the motor.
The food refrigerator of claim 6, wherein the first and the second portions are configured so as to allow access to the motor when the third portion is removed.
The food refrigerator of any of the preceding claims, wherein the air conveyor is provided with a plate (315) for mounting it to a cross-plate (210) at the bottom of a recess (130) of the refrigerator cabinet where the air conveyor is housed.
The food refrigerator of any one of the preceding claims, comprising a control unit for selectively activating the blower.