U.S. patent application number 12/225951 was filed with the patent office on 2009-07-02 for refrigeration device comprising a defrost heater.
This patent application is currently assigned to BSH Bosch und Siemens Hausgerate GmbH. Invention is credited to Jochen Harlen.
Application Number | 20090165486 12/225951 |
Document ID | / |
Family ID | 38513317 |
Filed Date | 2009-07-02 |
United States Patent
Application |
20090165486 |
Kind Code |
A1 |
Harlen; Jochen |
July 2, 2009 |
REFRIGERATION DEVICE COMPRISING A DEFROST HEATER
Abstract
A storage compartment and an evaporator compartment
communicating with said storage compartment via a cold air passage
and a hot air passage and comprising an evaporator and a defrost
heater. Said defrost heater, in a region adjacent to the hot air
passage, has a higher heating power density than in a region
adjacent to the cold air passage.
Inventors: |
Harlen; Jochen;
(Konigsbronn, DE) |
Correspondence
Address: |
BSH HOME APPLIANCES CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
100 BOSCH BOULEVARD
NEW BERN
NC
28562
US
|
Assignee: |
BSH Bosch und Siemens Hausgerate
GmbH
Munchen
DE
|
Family ID: |
38513317 |
Appl. No.: |
12/225951 |
Filed: |
March 12, 2007 |
PCT Filed: |
March 12, 2007 |
PCT NO: |
PCT/EP2007/052290 |
371 Date: |
October 3, 2008 |
Current U.S.
Class: |
62/276 |
Current CPC
Class: |
F25D 2317/0655 20130101;
F25D 2317/0683 20130101; F25D 2321/1441 20130101; F25D 21/14
20130101; F25D 17/067 20130101; F25D 21/08 20130101; F25D 2500/02
20130101 |
Class at
Publication: |
62/276 |
International
Class: |
F25D 21/08 20060101
F25D021/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 5, 2006 |
DE |
10 2006 015 994.2 |
Claims
1-12. (canceled)
13. A refrigeration device with a storage compartment and an
evaporator compartment which communicates with the storage
compartment via a cold air passage and a hot air passage and which
contains an evaporator and a defrost heater, characterized in that
the defrost heater has a higher heating power density in an area
adjacent to the hot air passage than it does in an area adjacent to
the cold air passage.
Description
[0001] The present invention relates to a refrigeration device with
a storage compartment and an evaporator compartment which
communicates with the storage compartment via a cold air passage
and a hot air passage and which contains an evaporator, at which
air flowing in from the storage compartment cools off and is
subsequently fed back into the storage compartment. These types of
refrigeration devices are also known as no-frost appliances.
[0002] Hot air flowing from the storage compartment into the
evaporator compartment takes moisture with it which tends to
precipitate on the evaporator so that a layer of ice builds up on
the latter during the operation of the refrigeration device. To
avoid any deterioration in the efficiency of the device, this layer
of ice must be removed from time to time. A defrost heater is
conventionally accommodated in the evaporator compartment for this
purpose which defrosts ice from the evaporator and lets it flow
away. The defrost water produced collects at the lowest point of
the evaporator compartment and from there passes through an outlet
into the open air where it can evaporate.
[0003] The defrosting process adversely affects the energy
efficiency of such a refrigeration device, since the heat energy
cannot be used completely for defrosting the ice. So that
defrosting can begin at all, the evaporator must namely first be
heated up from an operating temperature, which lies below 0.degree.
C., to 0.degree. C., and after the end of the defrost process the
evaporator must be cooled down again to its operating temperature,
before the storage compartment can be cooled again. In addition it
is inevitable that heat flows out of the evaporator compartment
into the storage compartment during defrosting, and said heat
subsequently has to be removed from the latter. Such a heat outflow
is all the stronger the higher the temperature in the evaporator
compartment during defrosting is.
[0004] To minimize the energy consumption during defrosting it is
thus desirable to implement in the evaporator compartment as
homogeneous as possible a distribution of the temperature which
only slightly exceeds the freezing point.
[0005] Surprisingly this object can be achieved in a simple manner
by the invention by a defrost heater which, in the area adjacent to
the hot air passage exhibits a higher heating power density than in
an area adjacent to the cold air passage.
[0006] The reason for this is that the air flowing through the
evaporator compartment unloads the moisture that it carries along
with it above all in an area adjoining the hot air passage, so that
the layer of ice decreases more rapidly in thickness there than in
the area adjoining the cold air passage. The fact that the area of
the evaporator adjacent to the hot air passage has a higher power
density applied to it than the area adjacent to the cold air
passage thaws the ice in the area adjacent to the hot air passage
rapidly, so that the layer of ice is essentially broken down over
the entire evaporator in the same time. Heating up of areas already
defrosted which leads to a large increase in temperature in said
areas can be avoided.
[0007] The heater preferably takes the form of a plate to allow it
to be placed along a main side of the evaporator
[0008] Preferably the heater extends below the evaporator, so that
air heated up at it can rise through the evaporator.
[0009] Preferably the heater has a carrier plate and a heating
element arranged on the carrier plate.
[0010] The heating element can be attached so as to form a flush
fit with the carrier plate material, for example by soldering, in
order to guarantee a good heat transfer from the heating element to
the plate. Another option to consider for attaching the heating
element to the plate might be by latching it on.
[0011] To promote heating of the evaporator by radiation as well,
the heating element is preferably arranged on a side of the plate
facing the evaporator.
[0012] It should also be spaced away from the plate over at least
part of its length, in order on the one hand not to adversely
affect the flow of defrost water which drips from the evaporator
onto the plate, on the other hand in order to limit an outflow of
heat from the heating element to the plate which would reduce the
effectiveness of the heat radiation.
[0013] It is also expedient in such a case for the plate to be made
from a material such as a metal which efficiently reflects the heat
radiation occurring, in order in this way to still direct heat
radiation which is radiated from the side facing away from the
heating element onto the evaporator.
[0014] In accordance with a first embodiment the heating element is
more densely arranged in the area of the carrier plate adjacent to
the hot air passage than in the area adjacent to the cold air
passage. This enables a heating element to be used with a heating
power which remains the same along its entire length per unit of
length.
[0015] Obstruction of the air flowing through the evaporator
compartment by the heating element can be kept low if the latter is
arranged in serpentines extending in the direction in which the air
passes To implement the different distribution of the heating power
at least one of the serpentines is then arranged entirely in the
area of the carrier plate adjacent to the hot air passage.
[0016] In accordance with a second embodiment the heating element
in the area adjacent to the hot air passage has a higher heating
power per unit of length than in the area adjacent to the cold air
passage. This enables a different distribution of the heating power
density to be implemented even if the heating element is arranged
in the same pattern in both areas.
[0017] To keep the structure of the heating element simple, it is
preferable in the latter case for the heating element to comprise
two sections connected in series, of which one fills the area
adjacent to the hot air passage and the other the area adjacent to
the cold air passage.
[0018] In the two sections the heating element can be arranged in
serpentines separated from each other in each case which extend in
the direction in which the air passes through the evaporator
compartment.
[0019] If a defrost water channel is provided on the floor of the
evaporator compartment, into which defrost water from the
evaporator flows, it can be worthwhile routing a section of the
heating element along the defrost water channel in order to ensure
that no ice residue prevents the defrost water in the defrost water
channel flowing away from the evaporator and a buildup of water
freezing again once the defrosting process has finished.
[0020] Further features and advantages of the invention emerge from
the description of exemplary embodiments given below which refer to
the enclosed figures. The figures are as follows:
[0021] FIG. 1 a schematic cross-section through an inventive
refrigeration device;
[0022] FIG. 2 a perspective view of the evaporator housing of the
refrigeration device from FIG. 1 with the defrost heater arranged
within it;
[0023] FIG. 3 an overhead view of the evaporator housing and the
evaporator mounted in it in accordance with a second embodiment of
the invention; and
[0024] FIG. 4 a schematic cross-section through an evaporator
housing in accordance with a third embodiment of the invention.
[0025] FIG. 1 shows a schematic section through the upper area of
an inventive refrigeration device. The refrigeration device has a
body 1 and a door 2, which are each implemented in a conventional
manner as hollow bodies filled with a heat-insulating foam layer 3.
The inside of the carcass 1 is divided up into an evaporator
compartment 5 and a storage compartment 6 by a dividing wall 4
which likewise provides heat insulation. The evaporator compartment
5 is largely filled by a housing 7 of an evaporator module in the
inner chamber of which an evaporator 8 of a design known per se
with vanes running in parallel for to the sectional plane and a
coolant line running at right angles to the vanes in serpentines is
mounted. A defrost heater 15 is accommodated below the evaporator 8
on the floor of the housing 7. The housing 7 has a hot air passage
9 on its side facing the door 2, through which hot air gets out of
the storage compartment 6 into the evaporator compartment 5, and a
passage 10 on its side facing the rear wall of the carcass 1 behind
which a fan 11 with blades 12 and a motor 13 is accommodated which
sucks air out of the housing 7 and pushes it into a cold air
passage 14 to the storage compartment 6.
[0026] FIG. 2 shows a perspective view of the housing 7 and of the
defrost heater 15 mounted within it. The housing 7 has a flat base
plate 18 sloping slightly towards the rear, which, with the
electrically-operated heating element mounted on it, forms the
defrost heater 15. The base plate 18 is made of metal or plastic,
with a metallic coating on its upper side, in order to divert the
heat radiation radiated downwards from the heating element upwards
onto the evaporator 8.
[0027] Between the base plate 18 and the rear wall 19 of the
housing 7 there is a defrost water drainage channel 20 on the floor
of the housing 7, extending over its entire width and inclined
towards a discharge opening 21.
[0028] The heating element comprises a plurality of serpentines 16,
17 running in the depth direction of the carcass 1. The serpentines
16, 17 are held on the base plate 18 with the aid of elastic clips
22 projecting from the base plate 18. The clips 22 hold the heating
element away from the base plate 18, so that defrost water dripping
from the evaporator 8 onto the base plate 18 can flow unimpeded
from the heating element into the drainage channel 20.
[0029] There are alternate short and long serpentines 16 or 17 in
the width direction of the base plate 18, with said serpentines
only extending in each case below an area of the evaporator 8
adjacent to the hot air passage 9 or below the entire evaporator 8
respectively and thus forming two sections with different heating
power densities. Alternatively serpentines can also be provided in
more than two different length stages, of which however all start
from the side of the evaporator 8 facing the hot air passage 9, in
order to heat the evaporator during operation most intensively in
its most heavily iced-up area. A straight section 23 of the heating
element extends along the drainage channel 20 in order to ensure
that no pieces of ice can remain in the latter to prevent the
outflow of defrost water.
[0030] FIG. 3 shows an overhead view of an evaporator housing 7
with an evaporator 8 and a defrost heater 25 in accordance with a
second embodiment of the invention. The shape of the housing 7 with
base plate 18 and drainage channel 20 is the same as that described
on the basis of FIG. 2, and the evaporator 8 with a coolant tube
held in vanes 28 is identical to that described in relation to FIG.
1. The heating element 25 has two sections 26, 27, which differ in
their heating output per unit of length. The more powerful section
26 runs below the area of the evaporator adjacent to the hot air
passage 9, and the less powerful section 27 below the section of
the evaporator adjacent to the rear wall 19 and thus adjacent to
the cold air passage. Both sections 26, 27 are laid according to
the same pattern, in the form of serpentines 30 extending in the
depth direction of the carcass. A serpentine 31 running at right
angles across the carcass 1, which belongs to the lower-power
section 27, heats the drainage channel 20.
[0031] FIG. 4 shows a third embodiment of the invention in cross
section. Here the heating element 15 with alternating long and
short serpentines 16, 17 of the type shown in FIG. 2 is not held
way from the base plate 18 but is connected to the latter for heat
conductance by solder 32. In order to prevent condensation water
building up on the curves 33 of the serpentines facing towards the
drainage channel 20, the short serpentines 16 are bent slightly
upwards in this embodiment, so that water can flow through between
them and the base plate 18; In the case of the long serpentines 17
the curves extend to over the drainage channel 20, so that here too
a free outflow is guaranteed.
* * * * *