EP2938943A1

EP2938943A1 - Cooling device with combined heater for dew and frost prevention

Info

Publication number: EP2938943A1
Application number: EP12813056.4A
Authority: EP
Inventors: Yasin AKSIN; Yigit OZSACMACI; Turgay Ercan; Gokhan Ozseker
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2012-12-28
Filing date: 2012-12-28
Publication date: 2015-11-04
Anticipated expiration: 2032-12-28
Also published as: CN105051473B; EP2938943B1; WO2014101962A1; CN105051473A; PL2938943T3

Abstract

A cooling device capable of operating either as a deep-freezer or as a fresh food refrigerator is disclosed. The device comprises an evaporator which is placed behind the rear wall of the storage compartment of the cooling device. The cooling device further comprises a combined heater having a defrost heater placed in thermal communication with said evaporator, and a rear wall heater placed in between said evaporator and the rear wall of the storage compartment of the cooling device.

Description

COOLING DEVICE WITH COMBINED HEATER FOR DEW AND FROST PREVENTION

The present invention relates to a combined heater for use in cooling devices having both refrigeration and deep freeze capability. The invention eliminates the need for using, a usually metal, heat shield for protecting the usually plastic rear wall of the storage volume of the cooling device from reverse heat flow from the evaporator, thus reducing the number of assembly parts and the material costs, eventually resulting in facilitation of the manufacturing process.
Cooling devices allowing optional use for refrigeration of perishable materials e.g. as a fresh food refrigerator or alternatively, as a deep-freeze, utilize an evaporator which is usually located between the rear wall of the storage compartment and the outer housing of the device. The evaporator serves for reducing the temperature of circulating air within the cooling device. The surface temperature of the evaporator may go as low as -27 deg. Celcius, which is way below the freezing temperature of water, eventually causing frost of the humidity contained in the circulating air. Nonetheless, the adjacent surface of the rear wall of storage compartment to the evaporator usually has a temperature between 2-10 deg. Celcius, when operated in fresh food preserving mode of the device. This temperature difference may cause dew formation on the inner surface of rear wall of the storage compartment adjacent to the evaporator.
In order to prevent dew formation on the inner surfaces of the rear wall of the storage compartment, heaters have been used conventionally for heating the rear wall of the storage compartment around the vicinity of the evaporator. In some cooling devices, a dew prevention device, namely an evaporator shield heater for continuous operation when the device is in fresh food refrigeration mode, is placed beneath a metal heat shield which protects the generally plastic rear wall, eventually preventing it from chronic contact with dew or water in liquid form. At these types of designs a usually metal heat shield is placed between the rear wall of the storage compartment and the evaporator, said shield also preventing sharp evaporator fins from damaging the back surface of the rear wall of the storage compartment.
As is disclosed in US5011101, a second heater, specifically a defrost heater is utilized for discrete operation in order to melt constantly accumulating frost on the cold evaporator surface. Assembly of such a system requires montage of a defrost heater neighboring to the evaporator, including a metal heat shield between the rear wall of the storage compartment and the evaporator for protecting said rear wall from sharp evaporator fins, and an evaporator shield heater on the back surface of said metal heat shield.
In JP53130560 (A) and JP2003322457 (A), dew prevention is intended by heating the door periphery. This design does not relate to the problem of dew deposition on the coldest surface points i.e. surfaces adjacent to the evaporator, where the dew deposition is most intense inside the refrigeration volume.
In JP2006220358 (A), a heating unit is located right on the backside of the rear wall of the storage compartment of a refrigerator, which was intended for cold air humidity deposition, in order to provide dew-and frost prevention around its vicinity. There is only one heater on the proposed system with the aim of targeting the water deposited on the surface of the rear wall of the storage compartment, and not the evaporator, hence failing to teach a dew and frost prevention system for cooling devices having both refrigeration and freezer modes.
In view of the problems with regards to the prior art information disclosed above, one of the objects of the present invention is to provide a dew and frost prevention system for cooling devices having both refrigeration and freezer modes, said system having a simplified structure with reduced parts and facilitated assembly and providing a cooling device equipped with a system as such.
A cooling device capable of operating either as a deep-freezer or as a fresh food refrigerator is disclosed. The device comprises a storage compartment and an evaporator located outside of said storage compartment. The storage compartment has a rear wall to which the evaporator is attached. The cooling device further comprises a combined heater having a defrost heater placed in thermal communication with said evaporator, and a heater placed in between said evaporator and the rear wall of the storage compartment such that said rear wall heater remains in thermal communication with both the evaporator and the rear wall of said storage compartment. In other words, the rear wall heater cushions in between said evaporator and said rear wall.
The cooling device according to the present invention may further comprise a controller which is configured to energize the heater of the rear wall of the storage compartment when the device is in fresh food refrigerator mode. The rear wall heater, in use, prevents dew formation on the rear surfaces of the storage compartment of the cooling device. The controller may be configured to energize both the rear wall heater and the defrost heater when the device is in defrost cycle. A defrost cycle is an operational mode during which frost formed on the evaporator is thaw out. A frost sensor may be located around the evaporator for facilitating detection of frost formation and commencing a subsequent defrost cycle.
The defrost heater according to the present invention is suitably located on a plane parallel to the plane of the rear wall heater. In an embodiment, the cooling device may further comprise a thermal insulation sheet between the evaporator and the rear wall heater. The purpose of the thermal insulation sheet is to reduce the heat flow from inside the storage room of the cooling device towards the evaporator so that dew formation in the storage room of the cooling device is reduced.
Accompanying drawings are given solely for the purpose of exemplifying a cooling device assembly whose advantages over the prior art were outlined above and will be explained in detail hereinafter:
Fig. 1 shows a sectional side view according to B–B axis of the cooling device according to the present invention. Some of the components such as the compressor are removed for simplicity.
Fig. 2 shows a frontal perspective view of the cooling device’s refrigeration compartment.
Fig. 3 shows a front view of the cooling device’s refrigeration compartment according to the present invention, where the B-B axis of Fig. 1 is marked.
Fig. 4 shows the frontal inner view of a cooling device according to the present invention.
Fig. 5 shows cross section view C-C of the cooling device of Fig. 4 according to the present invention.
Fig. 6 shows a rear perspective view of the rear wall of the storage compartment of a cooling device according to the present invention.
The following reference numerals have been used in the appended drawings which are given solely for the purpose of exemplifying the invention.
1. Rear wall
2. Evaporator shield heater
3. Evaporator shield
4. Evaporator
5a. Rear wall heater
5b. Defrost heater
7. Front door
8. Fan
Referring now to the figures outlined above, the inner assembly of a cooling device according to the present invention comprises an evaporator (4) which is placed behind the rear wall (1) of the storage compartment of the device and which serves for cooling the air circulated by a fan (8). This holds true irrespective of whether the device is operated in the deep-freezer mode or in refrigeration mode. The device further comprises a rear wall heater (5a) for preventing dew formation and potential liquid water deposition on the inside of the storage volume of cooling device; a defrost heater (5b) for removing the deposited ice on the cold evaporator surface caused by frozen water content of the circulated air, and a controller which is not shown in the figures.
Cooling devices allowing optional use as a fresh food refrigerator or as a deep freezer, usually utilize an evaporator (4) which is located outside of the storage volume of the device. A dew prevention device, namely an evaporator shield heater (2) operated during fresh food refrigeration mode, is placed behind and/or beneath an evaporator shield (3) for protecting the generally plastic rear wall (1) from being subject to chronic contact with water which forms due to the vast temperature difference of the evaporator (4) and the refrigeration compartment surfaces. Usually, an evaporator shield (3) is placed in between the rear wall (1) of the storage compartment and the evaporator (4), said shield further preventing the possibility of sharp evaporator fins from damaging the back surfaces of the rear wall (1) of the storage compartment.
The controller is configured to energize, as necessary to prevent dew formation, the rear wall heater (5a) when the device is in fresh food refrigerator mode. When in defrost cycle, said controller may energize both the rear wall heater (5a) and the defrost heater (5b) in order to shorten the duration of the defrost cycle. The rear wall heater (5a) in this latter case may help to melt down the frost accumulated on the evaporator. It must be kept in mind that the rear wall heater (5a) is placed in thermal communication with the evaporator and heat produced by the rear wall heater (5a) can easily be conveyed, through the metal body of the evaporator, to the opposite side of the evaporator (4) in order to help the frost heater (5b) melt accumulated frost. The rear wall heater (5a) cushions in between the rear wall (1) of the storage compartment of the cooling device and the evaporator (4) and this physical contact helps the heat produced by the rear wall heater (5a) be swiftly transferred through the body of the heater, which has very good heat transfer properties.
The present invention solves the problem of frost and dew prevention with a simplified design having a facilitated assembly. The present invention proposes an easy to install combined heater (5a, 5b) installed directly on the evaporator (4), in which one part, namely rear wall heater (5a) is used to heat the rear wall (1) on its back surface, whereas the second part, namely defrost heater (5b). Both heaters (5a,5b) are operable by a controller based on the operating mode of the device and settings of the user and operational conditions.
Fig. 1 shows a sectional side view of the cooling device according to the present invention. Components like the compressor are removed for simplicity. Having removed the front door (7), the inner volume of the cooling device of Fig. 1 is depicted in Fig. 2. The rear wall (1) of the storage compartment of the cooling device is depicted in Fig. 3.
Fig. 5 depicts the cross sectional view C-C of the cooling device of Fig. 4 according to the present invention. As apparently seen on Fig. 5, the rear wall heater (5a) is in thermal contact with the rear wall (1) of the storage compartment and the evaporator (4) and cushions in between the same. Fig. 5 depicts the rear wall heater (5a) as a planar heater located on the frontal surface of the evaporator (4) whereas the defrost heater (5b) is depicted on a plane in parallel to the plane of the rear wall heater (5a), located on the rear or opposite surface of the evaporator.
In an embodiment as shown in Fig. 1, a combined two part heater (5a,5b) is placed in direct contact with the evaporator (4) and without employing any isolation layer between said evaporator (4) and said combined two-part heater (5a,5b). This embodiment has an advantage of utilizing part of the heat transferred from the rear wall heater (5a) to function also as defrosting means; thus the work load on the defrost heater (5b) can be minimized and the periodic heating durations can be shortened, eventually resulting in lower energy consumption of the cooling device. It further results in an enhanced cooling performance of the evaporator (4), and hence shorter power-off term during defrost cycles.
It may be proposed to place a thermal insulation sheet between the evaporator (4) surface and the rear wall heater (5a) in an alternate embodiment. This alternate embodiment would have the advantage of enhanced channelizing of the heat generated by the rear wall heater (5a) towards the rear wall (1) of the storage compartment and save energy, without loading the evaporator (4) consuming energy for removing the thermal energy.

Claims

A cooling device capable of operating either as a deep-freezer or as a fresh food refrigerator, said device comprising a storage compartment and an evaporator (4) located outside of said storage compartment, said storage compartment having a rear wall (1) to which said evaporator (4) is attached characterized in that the cooling device further comprises a combined heater having;

- a defrost heater (5b) placed in thermal communication with said evaporator (4), and

- a rear wall heater (5a) placed in between said evaporator (4) and said rear wall (1) such that said rear wall heater (5a) remains in thermal communication with both the evaporator (4) and the rear wall (1) of said storage compartment.
A cooling device as claimed in Claim 1 wherein the device further comprises a controller configured to energize the rear wall heater (5a) when the device is in fresh food refrigerator mode.
A cooling device as claimed in Claim 2 wherein said controller is configured to energize both the rear wall heater (5a) and the defrost heater (5b) when the device is in defrost cycle.
A cooling device as set forth in Claim 1 wherein the cooling device further comprises a frost sensor located around the evaporator (4).
A cooling device as set forth in Claim 1 wherein the defrost heater (5b) is located on a plane parallel to the plane of the rear wall heater (5a).
A cooling device as set forth in Claim 1 wherein the device further comprises a thermal insulation sheet between the evaporator (4) and the rear wall heater (5a).