U.S. patent application number 10/845310 was filed with the patent office on 2005-01-06 for refrigerant compressor.
This patent application is currently assigned to Danfoss Compressor GmbH. Invention is credited to Bjerre, Preben, Iversen, Frank Holm.
Application Number | 20050002798 10/845310 |
Document ID | / |
Family ID | 33482132 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050002798 |
Kind Code |
A1 |
Bjerre, Preben ; et
al. |
January 6, 2005 |
Refrigerant compressor
Abstract
The invention concerns a refrigerant compressor with a motor, a
compressor driven by the motor, and a muffling device having at
least one muffler with a housing. It is endeavoured to reduce the
thermal influence of suction gas in the refrigerant compressor. For
this purpose, it is ensured that the housing has at least one outer
wall, which is made of a foamed plastic.
Inventors: |
Bjerre, Preben;
(Soenderborg, DK) ; Iversen, Frank Holm; (Padborg,
DK) |
Correspondence
Address: |
Richard R. Michaud
McCormick, Paulding & Huber LLP
CityPlace II
185 Asylum Street
Hartford
CT
06103
US
|
Assignee: |
Danfoss Compressor GmbH
Flensburg
DE
|
Family ID: |
33482132 |
Appl. No.: |
10/845310 |
Filed: |
May 13, 2004 |
Current U.S.
Class: |
417/312 ;
417/902 |
Current CPC
Class: |
F04B 39/0072
20130101 |
Class at
Publication: |
417/312 ;
417/902 |
International
Class: |
F04B 039/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 2003 |
DE |
103 23 527.2 |
Claims
What is claimed is:
1. A refrigerant compressor with a motor, a compressor driven by
the motor, and a muffling device having at least one muffler with a
housing, and wherein the housing has at least one outer wall, which
is made of a foamed plastic.
2. A compressor according to claim 1, wherein all outer walls are
made of foamed plastic.
3. A compressor according to claim 1, wherein the housing is made
of foamed plastic.
4. A compressor according to claim 1, wherein a connection line
between the muffler and the compressor is made of foamed
plastic.
5. A compressor according to claim 1, wherein the muffler is
located in a case, in which the motor and/or the compressor is
located.
6. A compressor according to claim 5, wherein a connection line
between the case and the muffler is made of foamed plastic.
7. A compressor according to claim 1, wherein the foamed plastic is
a foamed PBT.
8. A compressor according to claim 1, wherein the size of the cells
of the foamed plastic is in the range from 5 to 50 .mu.m.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is entitled to the benefit of and
incorporates by reference essential subject matter disclosed in
German Patent Application No. 103 23 527.2 filed on May 24,
2003.
FIELD OF THE INVENTION
[0002] The invention concerns a refrigerant compressor with a
motor, a compressor driven by the motor, and a muffling device
having at least one muffler with a housing.
BACKGROUND OF THE INVENTION
[0003] Such a refrigerant compressor is, for example, known from DE
195 16 811 C2. Here, the motor and the compressor are located in a
case together with a suction muffler. That is, a hermetically
enclosed refrigerant compressor is concerned, which has proved its
value for several years.
[0004] With such compressors, the refrigerant gas coming from the
evaporator is sucked in, compressed in the compressor, which
increases the temperature of the refrigerant gas, and then
discharged by a discharge nozzle, which in many cases communicates
with a pulsation muffler. In this connection, the colder the
refrigerant suction gas is, the better is the efficiency of the
compressor. The temperature of the refrigerant suction gas is,
however, already increased before entering the compressor, as the
refrigerant gas is exposed to a somewhat heated atmosphere inside
the case.
[0005] In order to remedy this problem, at least partly, U.S. Pat.
No. 4,371,319 suggests that in a hermetically enclosed compressor,
the cylinder head, the pressure muffler and the pressure line
should be supplied with an isolating layer inside the case.
However, this procedure is very expensive and requires a
substantial amount of space inside the case.
SUMMARY OF THE INVENTION
[0006] The invention is based on the task of reducing the thermal
influence of suction gas in the refrigerant compressor.
[0007] With a refrigerant compressor as mentioned in the
introduction, this task is solved in that the housing has at least
one outer wall, which is made of a foamed plastic.
[0008] With this embodiment, an improved thermal isolation towards
the environment of the gas entering the muffler is achieved,
without requiring an additional isolation layer. The housing itself
makes the isolation. As the outer wall of the housing is made by a
foamed plastic, it provides an excellent isolation. When the
muffler is used as a suction muffler, the suction gas remains
relatively cold, that is, it is not heated by the temperature
ruling in the case. When the muffler is arranged to be a pressure
or pulsation muffler at the outlet of the compressor, the outer
wall of the housing made of foamed plastic also provides thermal
isolation, so that the heat from the heated refrigerant gas is not
transferred to the environment. Also this is a measure, with which
an undesired heat transfer to the refrigerant suction gas can be
avoided. Of course, also a foamed plastic does not give perfect
thermal isolation, that is, heat will still be able to flow through
the outer wall. However, compared with a wall of massive plastic,
which has been used until now, the heat flow will be substantially
reduced, so that the thermal influence on the suction gas can be
reduced accordingly. Making at least one outer wall of a foamed
plastic will only increase the manufacturing costs of the muffler
insignificantly or not at all. On the other hand, however, the
efficiency of the compressor provided with the muffler is
increased, so that possible additional costs will be balanced very
soon.
[0009] Preferably, all outer walls are made of foamed plastic. This
gives improved heat isolation of the gas in the muffler towards the
environment. Additionally, a partly substantial noise muffling is
achieved. A foamed plastic can have better noise muffling
properties than a massive plastic, as an oscillation transfer
through a massive plastic can take place substantially more
directly than through a foamed plastic. It is assumed that the gas
bubbles contained in the foamed plastic obstruct a noise
penetration. Thus, a housing, all outer walls of which are made of
foamed plastic, offers two advantages.
[0010] It is preferred that the housing is made of foamed plastic.
This simplifies the manufacturing. Also, when chambers, bars or
other elements are provided in the housing, which are made in one
piece with the other housing parts during manufacturing, a foamed
plastic can be used. The foamed plastic is then also available
inside the housing with the mentioned elements. The result is a
housing for the suction muffler made of a substantially homogenous
material. Thus, the risk that fatigue phenomenon occur in
connection with material transitions, for example due to stress
crack corrosion, is relatively small.
[0011] Preferably, a connection line between the muffler and the
compressor is made of foamed plastic. Also the connection line
serves the purpose of isolating the gas thermally towards the
environment. This opportunity exists on the one hand with a
connection between a suction muffler and the compressor. In this
case, it is avoided that the suction gas is heated. On the other
hand, the possibility also exists with the connection from the
compressor to the pressure muffler. In this case, it is avoided
that heat is transferred from the connection line to the
environment.
[0012] Preferably, the muffler is located in a case, in which the
motor and/or the compressor are located. In this case, the use of a
muffler, which is completely or partly made of foamed plastic, is
particularly advantageous. As stated above, an increased
temperature is usually available in a closed case, as the
compressor, in which the refrigerant gas is compressed, causes a
temperature increase in the refrigerant gas during compression.
This increased temperature radiates into the inside of the case.
When now, particularly a suction muffler of a foamed plastic is
used, the refrigerant gas, which is sucked in, is kept cold and the
efficiency of the compressor increases.
[0013] It is preferred that a connection line between the case and
the muffler is made of foamed plastic. Thus, a heat transfer does
not take place via the path between the inlet of the case and the
muffler or between the muffler and the outlet of the case,
respectively.
[0014] Preferably, the foamed plastic is a foamed PBT. PBT has
proved its suitability for use in refrigerant circuits. Now,
basically the same material can be used, and it must merely be
ensured by means of a foaming during or before the manufacturing
that the housing of the muffler is completely or partly made by the
foamed PBT.
[0015] Preferably, the size of the cells of the foamed plastic is
in the range from 5 to 50 .mu.m. Thus, very small cells are
concerned, which are substantially smaller than those of
"traditional" PBT foam. With such small cells, a high mechanical
strength is achieved so that the dimensions of the walls of the
muffler can be left more or less unchanged. A slight increase in
the thickness, however, is harmless. Foamed PBT with such small
cells are commercially available under the name "MuCell" from the
company Trexel, Inc., Woburn, Mass., USA:
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In the following, the invention is described on the basis of
a preferred embodiment in connection with the drawings,
showing:
[0017] FIG. 1 is a schematic sectional view through a refrigerant
compressor
[0018] FIG. 2 is a suction muffler, partially in front view
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] FIG. 1 shows a refrigerant compressor 1 with a motor 2,
which drives a compressor 3. The motor 2 has a stator 4 and a rotor
5. The rotor 5 is connected with a shaft 6, which drives a piston 8
in a cylinder 9 via a crankshaft drive 7. The cylinder 9 is closed
by a cylinder head 10, in which, in a manner known per se, valves
are located, which control the filling of a compression chamber in
the cylinder 9 with refrigerant gas, or the discharge of the
refrigerant gas from the compression chamber, respectively.
[0020] The parts mentioned are enclosed in a case 11, which
encloses the motor 2 and the compressor 3 hermetically. The outside
of the case is provided with an electronic connection device 12, if
required with a control, which controls the operation of the motor
2 in dependence of predetermined values, for example the
refrigeration requirement of a refrigerator, not shown in detail.
The device 12 is connected with the motor 2 via lines 13 guided
through the case.
[0021] Refrigerant gas is supplied by an evaporator, not shown in
detail, to a suction muffler 15 via a suction nozzle 14. The
suction muffler 15 is connected with the cylinder head 10 via a
line 16 (FIG. 2). In a manner not shown in detail, the cylinder
head 10 is connected with a pressure muffler 17 via a pressure
line, the pressure muffler discharging compressed and heated
refrigerant gas from the case 11 via a discharge nozzle 18.
[0022] The suction nozzle 14 extends into a suction line 19, which
is located inside the case 11. By way of a flange 20, the suction
line 19 bears on a contact surface 21 of the housing 22 of the
suction muffler 15.
[0023] The housing 22 is formed by an top part 23 and bottom part
24, which bear on each other with flanges 25, 26, which can be
stepped, if required, and are connected with each other along a
contact face 27, for example by means of welding.
[0024] Inside the housing 22 is formed a muffling chamber 28. In
the muffling chamber is located a pipe 29, which forms a gas
conduit 30, through which refrigerant gas can flow from the inlet
31 of the suction muffler 15 to the outlet 32. This embodiment is
only chosen as an example. It is of course also possible to design
the suction muffler 15 differently.
[0025] The housing 22 of the suction muffler 15 is made of a foamed
plastic. Also the pipe 29 is made of the foamed plastic. The foamed
plastic is a foamed PBT (polybutylene terephthalate) with evenly
distributed cells in the size range 5 to 50 .mu.m. Such a material
is, for example, commercially available under the name "MuCell"
from the company Trexel, Inc., Woburn, Mass., USA. It is
characterised in having substantially smaller cells than
traditional, foamed PBT with cells in the size range of 250
.mu.m.
[0026] Such a foamed PBT (or another foamed plastic) has the
advantage that a heat transfer from the atmosphere ruling inside
the case 11 to the refrigerant suction gas is only possible to a
heavily reduced extent. Thus, the refrigerant gas is not further
heated inside the case 11. On the other hand, making the suction
muffler 15 of foamed plastic has the advantage that noises
occurring inside the suction muffler through the flowing and
pulsating gas can be even better muffled. Thus, the foamed plastic
forms an acoustic muffler.
[0027] The foamed plastic can, for example, be made in that
nitrogen or carbon dioxide under a high pressure is supplied as
supercritical fluid to the molten polymer in an extruder or an
injection moulding device, and suddenly the pressure is reduced,
after which the housing of the suction muffler 15 can be made in
practically the traditional way. With this manufacturing method, it
is possible to adopt the wall thicknesses, which have until now
been chosen for the parts, of which the suction muffler consists,
in a practically unchanged form. Small dimension changes are
insignificant.
[0028] Of course, also the pressure muffler 17 can be made of the
foamed plastic. In this case, the foamed plastic prevents a heat
transfer from the refrigerant gas heated by the compression to the
environment inside the case 11. This also reduces the thermal
influences on the refrigerant suction gas.
[0029] The colder the refrigerant gas entering the compressor 3 is,
the higher is the efficiency of the compressor. The use of a foamed
plastic thus causes efficiency improvements.
* * * * *