U.S. patent application number 12/249107 was filed with the patent office on 2009-04-30 for refrigerant compressor arrangement.
This patent application is currently assigned to Danfoss Compressors GmbH. Invention is credited to Jens Erik Nissen, Svend Erik Outzen, Carsten Petersen.
Application Number | 20090110585 12/249107 |
Document ID | / |
Family ID | 40435418 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090110585 |
Kind Code |
A1 |
Outzen; Svend Erik ; et
al. |
April 30, 2009 |
REFRIGERANT COMPRESSOR ARRANGEMENT
Abstract
The invention concerns a refrigerant compressor arrangement with
a compressor unit (2) supported in a case by means of springs (12)
and comprising at least one bolt (26) with a bolt head (25), a
holder (23) being arranged between the compressor unit (2) and at
least one spring (12), the holder (23) having in its front a
recess, in which the bolt head (25) engages, and which is connected
to the spring (12). It is endeavoured to reduce the noise
generation during operation of the refrigerant compressor
arrangement. For this purpose, the bolt head (25) is arranged in
the recess (24) with lateral clearance (34).
Inventors: |
Outzen; Svend Erik;
(Soenderborg, DK) ; Nissen; Jens Erik; (Graasten,
DK) ; Petersen; Carsten; (Flensburg, DE) |
Correspondence
Address: |
MCCORMICK, PAULDING & HUBER LLP
CITY PLACE II, 185 ASYLUM STREET
HARTFORD
CT
06103
US
|
Assignee: |
Danfoss Compressors GmbH
Flensburg
DE
|
Family ID: |
40435418 |
Appl. No.: |
12/249107 |
Filed: |
October 10, 2008 |
Current U.S.
Class: |
418/179 |
Current CPC
Class: |
F04B 39/127 20130101;
F04B 39/0044 20130101 |
Class at
Publication: |
418/179 |
International
Class: |
F04C 15/00 20060101
F04C015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2007 |
DE |
10 2007 048 936.8 |
Claims
1. A refrigerant compressor arrangement with a compressor unit
supported in a case by means of springs and comprising at least one
bolt with a bolt head, a holder being arranged between the
compressor unit and at least one spring, the holder having in its
front a recess, in which the bolt head engages, and which is stuck
together with the spring, wherein the bolt head is arranged in the
recess with lateral clearance.
2. The refrigerant compressor arrangement in accordance with claim
1, wherein the size of the lateral clearance is in the range from
0.2 to 0.5 mm.
3. The refrigerant compressor arrangement in accordance with claim
1, wherein the compressor unit rests on the front side and the
recess has a depth, which is larger than an extension of the bolt
head in the depth direction.
4. The refrigerant compressor arrangement in accordance with claim
3, wherein a difference between the depth of the recess and the
extension of the bolt head has a size in the range from 0.4 to 1
mm.
5. The refrigerant compressor arrangement in accordance with claim
1, wherein the holder is made of a plastic material that interacts
smoothly with the compressor unit, and the holder and the
compressor unit bear on each other with smooth surfaces.
6. The refrigerant compressor arrangement in accordance with claim
1, wherein the bolt head has an undercut in its circumferential
surface, behind which projections directed inwardly in the recess
engage the holder.
7. The refrigerant compressor arrangement in accordance with claim
6, wherein the recess is surrounded by a circumferential wall, in
which at least two slits extending from the inside to the outside
are arranged.
8. The refrigerant compressor arrangement in accordance with claim
6, wherein in the axial direction the projections have a smaller
extension than the undercut.
9. The refrigerant compressor arrangement in accordance with claim
1, wherein the holder is made as a hollow body.
10. The refrigerant compressor arrangement in accordance with claim
1, wherein the front side is formed on a side of a front side wall,
which has several recesses on the bottom side opposite to the front
side.
11. The refrigerant compressor arrangement in accordance with claim
10, wherein the recesses are open in the direction of the
circumferential wall of the holder.
12. The refrigerant compressor arrangement in accordance with claim
1, wherein the holder is made of an electrically isolating plastic
material.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] Applicant hereby claims foreign priority benefits under
U.S.C. .sctn. 119 from German Patent Application No. 10 2007 048
936.8 filed on Oct. 12, 2007, the contents of which are
incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention concerns a refrigerant compressor arrangement
with a compressor unit supported in a case by means of springs and
comprising at least one bolt with a bolt head, a holder being
arranged between the compressor unit and at least one spring, the
holder having in its front a recess, in which the bolt head
engages, and which is stuck together with the spring.
BACKGROUND OF THE INVENTION
[0003] Such a refrigerant compressor arrangement is known from, for
example, U.S. Pat. No. 4,106,881. The compressor unit has an
electric motor with a vertically extending shaft. Above the motor a
compressor is arranged, which comprises a piston reciprocating in a
cylinder. The piston is driven by the rotary movement of the rotor
of the motor. The stator lamination of the motor is kept together
by means of bolts. The head of each bolt is inserted in a holder,
which again is inserted in a spring. The spring again is mounted on
a holding element, which is fixed at the bottom of the case.
[0004] A similar embodiment is known from U.S. Pat. No.
4,406,590.
[0005] During operation of the compressor unit, the reciprocating
movement of the piston of the compressor generates a vibration of
the compressor unit. The springs are provided to ensure that such
vibrations are not, or at least only to a limited extent,
transferred to the case. Vibrations, which should reach the case,
would be passed on to the refrigeration appliance, in which the
refrigerant compressor arrangement is mounted. When the
refrigeration appliance starts vibrating, a partly substantial
noise level is generated.
SUMMARY OF THE INVENTION
[0006] The invention is based on the task of preventing a noise
generation.
[0007] With a refrigerant compressor arrangement as mentioned in
the introduction, this task is solved in that the bolt head is
arranged in the recess with lateral clearance.
[0008] In the gravity direction, the compressor unit is still
supported by means of the holder. The holder transfers the weight
forces of the compressor unit to the spring or the springs, when
more or even all springs are connected to the compressor unit via
corresponding holders. The oscillations occurring in the compressor
unit are substantially directed perpendicularly to the active
direction of the springs. The springs support the compressor unit
in the gravity direction. When, now, a small movability of the
compressor unit in relation to the holder is permitted, a vibration
of the compressor unit can move the compressor unit a bit, before
it starts moving the holder. Accordingly, the movement finally
performed by the holder is smaller than it would be with a
form-fitting connection between bolt head and holder. A movement
with smaller amplitude will transfer a correspondingly smaller
amount of energy to the case via the spring. Accordingly, a noise
generation will be reduced. This is particularly the case for a
frequency range around 800 Hz, which is particularly inconvenient
for a user. In this frequency range, the amplitudes of the
vibrations are relatively small, so that a lateral clearance does
not have to be excessively large. This means that the bolt head is
still guided to a sufficient degree in the holder.
[0009] It is preferred that the size of the lateral clearance is in
the range from 0.2 to 0.5 mm. For example, the clearance can have a
size of 0.25 to 0.35 mm. If the oscillation amplitudes are smaller
than this clearance, a lateral contact between the bolt head and
the holder is completely avoided, so that an oscillation transfer
from the compressor unit via the holder to the spring and thus to
the case is completely avoided. If the vibration amplitude is
larger, the vibration of the compressor unit will also move the
holder. However, as stated above, this movement has smaller
amplitude, so that the transfer of energy is reduced.
[0010] Preferably, the compressor unit rests on the front side and
the recess has a depth, which is larger than an extension of the
bolt head in the depth direction. This results in a clearance also
in the axial direction. The "axial direction" is the direction of
the bolt axis. The compressor unit will then only be supported on
the front side of the holder. The bolt head itself is arranged in
the holder with a clearance, both circumferentially and at its
front side, so that a friction between the front side of the bolt
head and the holder is also avoided.
[0011] Preferably, a difference between the depth of the recess and
the extension of the bolt head has a size in the range from 0.4 to
1 mm. In particular, this clearance can have a size between 0.5 and
0.7 mm. Also this clearance is not particularly large. However, it
is sufficient to achieve a decoupling, at least substantially, with
regard to oscillations between the compressor unit and the
holder.
[0012] Preferably, the holder is made of a plastic material that
interacts smoothly with the compressor unit, and the holder and the
compressor unit bear on each other with smooth surfaces. Thus, it
is possible that a relative movement between the compressor unit
and the holder occurs, so that a movement transfer from the
compressor unit to the holder does not take place, or at least only
to a limited extent. The smaller the movement is, which is
eventually performed by the holder, the smaller is the risk that
noises are transferred to the environment via the case.
[0013] Preferably, the bolt head has an undercut in its
circumferential surface, behind which projections directed inwardly
in the recess engage the holder. This simplifies the manufacturing
of the refrigerant compressor arrangement. If the holder is mounted
on the bolt head with a clearance, it would fall off during
assembly, if the compressor unit with bottom-mounted holder were
moved. If, however, an undercut on the bolt head is used, in which
the projections of the holder engage, the clearance between the
bolt head and the holder can be maintained and the holder would
still be fixedly held at the bolt head. After assembling the holder
on the bolt head, the compressor unit with the holders hanging
downwards in the gravity direction can still be moved without
loosing the holders. The holders can then be connected to the
springs in a simple manner.
[0014] Preferably, the recess is surrounded by a circumferential
wall, in which at least two slits extending from the inside to the
outside are arranged. These slits cause that the circumferential
wall can more easily be outwardly deformed in an elastic manner.
This is advantageous, both during the manufacturing of the holder
and during manufacturing of the refrigerant compressor arrangement.
During manufacturing of the holder, the holder can more easily be
removed from a mould, for example an injection mould. The
projections themselves do not have to be deformed; on the contrary,
the circumferential wall is deformed. When mounting the holder on
the bolt head, the holder is, in a manner of speaking, snapped onto
the bolt head. When the circumferential wall has sprung back to its
original shape, the projections are held in the recess.
[0015] Preferably, in the axial direction the projections have a
smaller extension than the undercut. In spite of the projections
extending into the undercut, this leaves the clearance between the
bolt head and the holder in the axial and in the lateral or radial
directions. If the compressor unit bears on the front side of the
holder, at least one position of the bolt head exists, in which
none of the projections is in touch with the bolt head.
[0016] Preferably, the holder is made as a hollow body. This means
that the holder surrounds a hollow, which can without problems be
downwardly open. This saves weight. The lighter the holder is, the
less noise energy it can transfer from the compressor unit to the
springs and the less are the noises penetrating to the
environment.
[0017] Preferably, the front side is formed on a side of a front
side wall, which has several recesses on the bottom side opposite
to the front side. The recesses also provide a mass reduction. At
the same time, the supports remaining between the recesses ensure
that the front side wall has a sufficient stability to adopt the
weight force of the compressor unit.
[0018] Preferably, the recesses are open in the direction of the
circumferential wall of the holder. Also this is a further measure
for saving weight.
[0019] Preferably, the holder is made of an electrically isolating
plastic material. Thus, it is avoided that currents from the
compressor unit, particularly from the motor of the compressor
unit, can reach the case via the holder and the spring. Thus, a
danger for third parties is avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In the following, the invention is explained on the basis of
a preferred embodiment in connection with the drawings,
showing:
[0021] FIG. 1 is a vertical section through a refrigerant
compressor arrangement;
[0022] FIG. 2 is a schematic top view of the opened refrigerant
compressor case;
[0023] FIG. 3 is a perspective view of a holder with bolts;
[0024] FIG. 4 is a perspective bottom view of the holder;
[0025] FIG. 5 is a section through a holder; and
[0026] FIG. 6 is a section through a holder with bolts and
spring.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS
[0027] A compressor unit 2 is arranged in a case 1. A compressor
housing 4 is connected to a stator 3 of an electric motor, the
compressor housing 4 comprising a cylinder 5 and a bearing 6. In
the bearing 6 a motor shaft 7 is supported, which carries a rotor 8
and drives a piston 11 via a crank pin 9 and a connecting rod 10,
the piston 11 reciprocating in the cylinder 5. Helical compression
springs 12 provide an elastic support for the compressor unit 2 in
the case 1. Also a pressure pipe 13 is made to be elastic.
[0028] For adopting a cylinder head 14 projecting radially over the
stator 3, an enlargement 15 is provided in the case 1. This
enlargement also comprises an electric bushing 16 with bushing pins
17, whose inner ends carry a plug 18. In the bottom part of the
case 1, both sides of the bushing 16 are provided with concavities
19 and 20. In this way, the wall of the case 1 forms four abutments
W1-W4, which can interact with four stops A1-A4, which are arranged
on the compressor unit 2. These stops are located at the bottom
side of the, in the present case, square stator 3. The edges 21 of
the stator 3 are bevelled in such a manner that in all positions
they have approximately the same distance to the corresponding
abutments W1-W4. The stops A1-A4 project over these bevelled edges
in such a manner that they limit a displacement of the compressor
unit 2 in any movement direction in the drawing level of FIG. 2 by
coming to rest on the abutments. In this connection, the bushing 16
and the plug 18 are safely protected between the concavities 19,
20.
[0029] The stops A1-A4 are formed by a collar of a holder 23 for
the helical compression springs 12. This holder 23 has a recess 24,
into which a bolt head 25 of a bolt 26 is inserted. A holder of
metal is welded onto the bottom of the case 1. The holder 23
consists of a refrigerant resistant and electrically isolating
plastic material.
[0030] In order to prevent an impermissibly large upward
displacement of the compressor unit 2, a bracket 29 is fixed by
means of bolts on the upper side of the stator on the side opposite
the cylinder 5. Further, an angularly shaped projection 30 is fixed
at the case 1 with a small distance above the bracket 29. The upper
side 31 of the cylinder head 14 has approximately the same distance
from the covering wall 32 of the case 1.
[0031] During operation of the compressor unit 2, vibrations occur,
mainly transversally to the rotation axis of the vertically
arranged motor shaft 7. If these vibrations are transferred to the
case 1 and from there to elements, in which the case is mounted,
for example refrigeration appliances, a relatively high noise load
will occur in the environment of the case 1. A part of the
oscillations will be suppressed by the helical compression springs
12 and thus only be transferred to the case 1 with a small
intensity. None the less, interfering noises will remain, which can
penetrate to the environment.
[0032] A special embodiment of the holders 23, as shown in the
FIGS. 3 to 6, will further reduce the noise generation.
[0033] The holder 23 is made of a plastic material, which interacts
with the metal of the stator 3 in a low-friction manner. Such a
plastic material is known by its commercial name "HALAR". The
material is a fluor polymer, which combines the chemical
resistibility to aggressive refrigerants and the lubricating oil
with a dimension stability, and which further has a smooth surface.
Finally, this plastic material is electrically isolating, so that
it prevents the transfer of leakage currents or other currents from
the motor to the case 1.
[0034] The holder 23 has a front side 31, which is made to be
smooth and which interacts with a smooth bearing surface 32 of the
stator 3. This means that the stator 3 can slide on the holder
23.
[0035] In order to permit this sliding, the bolt head 25 is
supported in the recess 23 with a radial and an axial clearance. In
this connection, the directions "radial" and "axial" refer to an
axis 33 of the bolt 26.
[0036] The clearance 34 in the radial direction has a size of 0.1
to 0.5 mm, for example 3 mm. The clearance 35 in the axial
direction has a size in the range from 0.4 to 1 mm, for example 0.6
mm. Such a clearance is not large. However, it is sufficient to
reduce a corresponding oscillation transfer from the stator 3 to
the helical compression spring 12.
[0037] The holder has several projections 36, which extend radially
into the recess 26. The bolt head 25 has an undercut 37, behind
which the projections 36 engage, when the bolt head 25 is inserted
in the recess 24.
[0038] In this connection, the undercut 37 is dimensioned in
relation to the projections 36 in such a manner that, also when the
bolt head 25 is inserted in the recess 24, an axial and radial
clearance between the holder 23 and the bolt head 25 remains. In
other words, the projections 36 have a smaller axial extension than
the undercut 37. Thus, when assembling the refrigerant compressor
arrangement, the holder 23 can also be mounted on the bolt head 25
from below, when the compressor unit is transported with downwardly
hanging holders 23. Together with the undercut 37, the projections
36 retain the holders 23 reliably at the stator. Then, the holders
23 can simply be inserted in the helical compression springs 12 to
form a plug connection.
[0039] The front side 31 is formed on a front side wall 38. In the
circumferential direction, several slits 39 are distributed on this
front side wall 38, so that the front side wall 38 can be somewhat
outwardly deformed, if this is required. This requirement, for
example, occurs, if the holder 23 is injection moulded of a plastic
material and has to be removed from a mould after the injection
process. In this case, a corresponding core can simply be pulled
out from the holder 23, which causes that the projections 36
together with the front side wall 38 can yield radially outwards. A
yielding is also appropriate, when the bolt head 25 is inserted in
the recess 24.
[0040] Otherwise, the holder 23 is made as a hollow body, that is,
it surrounds a hollow 40, which extends into an opening 40 in the
bottom wall 41 of the holder 23. The lighter the holder 23 is, the
smaller is the risk that oscillations will be transferred to the
helical compression springs 12 via the holder 23. On the side
opposite the front side 31, the front side wall 38 has several
recesses 43, which open downwardly and in the direction of the
circumferential wall. Also with such an embodiment, mass is saved.
Abutments 44 will remain between the recesses 43, by means of which
the holders 23 rest on their helical compression springs 12.
[0041] While the present invention has been illustrated and
described with respect to a particular embodiment thereof, it
should be appreciated by those of ordinary skill in the art that
various modifications to this invention may be made without
departing from the spirit and scope of the present invention.
* * * * *