U.S. patent application number 11/459708 was filed with the patent office on 2007-01-25 for suspension for linear compressor.
Invention is credited to Crispin Roger Halkyard, Adrian Chaplin Jaan Hills, Ian Campbell McGill.
Application Number | 20070020122 11/459708 |
Document ID | / |
Family ID | 37679227 |
Filed Date | 2007-01-25 |
United States Patent
Application |
20070020122 |
Kind Code |
A1 |
Halkyard; Crispin Roger ; et
al. |
January 25, 2007 |
Suspension for Linear Compressor
Abstract
A refrigeration system compressor including a hermetic housing
and a linear compressor within said hermetic housing. The
compressor includes at least two relatively reciprocating parts,
with one part typically being much greater mass than the other
part. The relative reciprocation of the centre of mass of each part
occurs along an axis of reciprocation. The compressor hangs from a
pair of suspension elements. Each suspension element includes a
first attachment portion connected to the compressor and a second
attachment portion connected to an upper support point above the
compressor. A body spans between the first attachment portion and
the second attachment portion. The body comprises a flexible planar
or linear element, oriented perpendicular to the axis of
reciprocation of the compressor.
Inventors: |
Halkyard; Crispin Roger;
(North Shore City, NZ) ; McGill; Ian Campbell;
(Auckland, NZ) ; Jaan Hills; Adrian Chaplin;
(Auckland, NZ) |
Correspondence
Address: |
TREXLER, BUSHNELL, GIANGIORGI,;BLACKSTONE & MARR, LTD.
105 WEST ADAMS STREET
SUITE 3600
CHICAGO
IL
60603
US
|
Family ID: |
37679227 |
Appl. No.: |
11/459708 |
Filed: |
July 25, 2006 |
Current U.S.
Class: |
417/363 |
Current CPC
Class: |
F04B 35/045
20130101 |
Class at
Publication: |
417/363 |
International
Class: |
F04B 35/00 20060101
F04B035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2005 |
NZ |
541461 |
Claims
1. A suspension element supporting a linear compressor within a
hermetic shell, said suspension element comprising: a first
attachment portion connected to the compressor, a second attachment
portion connected to an upper support point above the compressor,
and a body spanning between said first attachment portion and said
second attachment portion, said body comprising a flexible planar
or linear element, oriented perpendicular to the axis of
reciprocation of said compressor.
2. A suspension element as claimed in claim 1 wherein said flexible
element comprises a thin polymer sheet material.
3. A suspension element as claimed in claim 1 wherein said flexible
element comprises a planar fibre reinforced plastic sheet.
4. A suspension element as claimed in claim 1 wherein said first
attachment portion is connected to said compressor substantially on
or below an axis coinciding with the reciprocating axis of the
centre of mass of said compressor.
5. A suspension element as claimed in claim 4 wherein said planar
web comprises at least a pair of spokes diverging from said first
attachment portion to said second attachment portion.
6. A suspension element as claimed in claim 1 wherein said first
attachment portion is a bent or folded portion of said sheet and
said bent or folded portion is held in a clamp.
7. A suspension element as claimed in claim 6 wherein said second
attachment portion is a bent or folded portion of said sheet, and
said bent or folded portion is held in a clamp.
8. A refrigeration system compressor comprising a hermetic housing,
a linear compressor within said hermetic housing, said compressor
including at least two relatively reciprocating parts, with one
part typically being much greater mass than the other part, the
relative reciprocation of the centre of mass of each part occurring
along an axis of reciprocation, and a first suspension element
comprising: a first attachment portion connected to the compressor,
a second attachment portion connected to an upper support point
above the compressor, and a body spanning between said first
attachment portion and said second attachment portion, said body
comprising a flexible planar or linear element, oriented
perpendicular to the axis of reciprocation of said compressor; and
a second suspension element comprising: a first attachment portion
connected to the compressor, a second attachment portion connected
to an upper support point above the compressor, and a body spanning
between said first attachment portion and said second attachment
portion, said body comprising a flexible planar or linear element,
oriented perpendicular to the axis of reciprocation of said
compressor; the first attachment portion of each said suspension
element being connected with said compressor part of greater mass,
and the second attachment portion of each said element being fixed
to one part of said hermetic housing, such that substantially the
entire weight of said compressor hangs from said second attachment
portions.
9. A compressor as claimed in claim 8 wherein said flexible element
comprises a thin polymer sheet material.
10. A compressor as claimed in claim 8 wherein said flexible
element comprises a planar fibre reinforced plastic sheet.
11. A compressor as claimed in claim 8 wherein the second
attachment portion of at least one of said first and second
suspension elements is connected to said compressor at or below an
axis coinciding with the reciprocating axis of the centre of mass
of the compressor.
12. A compressor as claimed in claim 11 wherein said body comprises
at least a pair of spokes diverging from said first attachment
portion to said second attachment portion.
13. A compressor as claimed in claim 11 wherein said compressor
includes an inverted suspension element comprising: a first
attachment portion connected to the compressor and a second
attachment portion connected to a lower support point below the
compressor, and a body spanning between said first attachment
portion and said second attachment portion, said body comprising a
flexible planar or linear element oriented perpendicular to the
axis of reciprocation of said compressor.
14. A compressor as claimed in claim 11 wherein said second
attachment portion is connected to said compressor below said axis
of reciprocation of said centre of mass, and said compressor
includes an inverted suspension element comprising: a first
attachment portion connected to the compressor and a second
attachment portion connected to a lower support point below the
compressor, and a body spanning between said first attachment
portion and said second attachment portion, said body comprising a
flexible planar or linear element oriented perpendicular to the
axis of reciprocation of said compressor.
15. A compressor as claimed in claim 14 wherein said first
attachment portion of said inverted suspension element connects to
said compressor above said axis coinciding with the reciprocation
axis of the centre of mass of said compressor.
16. A compressor as claimed in claim 15 wherein the planar web of
one said suspension element comprises at least a pair of spokes
diverging from said first attachment portion to said second
attachment portion and wherein said first attachment portion of
said suspension element is adjacent the gap between said
spokes.
17. A compressor as claimed in claim 16 wherein said body of said
other suspension element comprises at least a pair of spokes
diverging from said first attachment portion to said second
attachment portion, and said first attachment portion of said one
suspension element is adjacent the gap between spokes of said
inverted suspension element.
18. A compressor as claimed in claim 13 including a suspension
frame, said second attachment portion of the upper of said
suspension elements connected to an upper portion of said frame,
and said second attachment portion of the lower of said suspension
elements connected to a lower portion of said frame.
19. A compressor as claimed in claim 17 including a suspension
frame, said second attachment portion of the upper of said
suspension elements connected to an upper portion of said frame,
and said second attachment portion of the lower of said suspension
elements connected to a lower portion of said frame.
20. A compressor as claimed in claim 16 wherein a compressor
mounting for at least one additional suspension element passes
through the gap between said spokes of said body.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to linear compressors, and in
particular linear compressors of the type suitable for use in a
vapour compression refrigeration system.
BACKGROUND TO THE INVENTION
[0002] Linear compressors of a type for use in a vapour compression
refrigeration system are the subject of many documents in the prior
art. One such document is our co-pending PCT patent application
PCT/NZ2004/000108. That specification describes a variety of
developments relating to compressors, many of which have particular
application to linear compressors. The present invention relates to
further improvements to compressor embodiments such as are
described in that patent application, which provides a general
description of an example compressor to which the present invention
may be applied. However the present invention may also be applied
beyond the scope of the particular embodiments of linear compressor
disclosed in that application. Persons skilled in the art will
appreciate the general application of the ideas herein to other
embodiments of linear compressors such as are found in the prior
art.
[0003] The present invention relates generally to suspension
elements for suspending the compressor assembly within the hermetic
shell. PCT/NZ2004/000108 describes several suspension arrangements
using coil springs.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a
suspension element with improved characteristics with particular
application to linear compressors and/or to provide refrigeration
compressors incorporating such suspension elements, or to at least
provide the industry with a useful choice.
[0005] In a first aspect the invention consists in a suspension
element supporting a linear compressor within a hermetic shell,
said suspension element comprising:
[0006] a first attachment portion connected to the compressor, a
second attachment portion connected to an upper support point above
the compressor, and a body spanning between said first attachment
portion and said second attachment portion, said body comprising a
flexible planar or linear element, oriented perpendicular to the
axis of reciprocation of said compressor.
[0007] In a further aspect the present invention consists in a
refrigeration system compressor comprising a hermetic housing, a
linear compressor within said hermetic housing, said compressor
including at least two relatively reciprocating parts, with one
part typically being much greater mass than the other part, the
relative reciprocation of the centre of mass of each part occurring
along an axis of reciprocation, and
[0008] a first suspension element comprising:
[0009] a first attachment portion connected to the compressor, a
second attachment portion connected to an upper support point above
the compressor, and a body spanning between said first attachment
portion and said second attachment portion, said body comprising a
flexible planar or linear element, oriented perpendicular to the
axis of reciprocation of said compressor;
[0010] and a second suspension element comprising:
[0011] a first attachment portion connected to the compressor, a
second attachment portion connected to an upper support point above
the compressor, and a body spanning between said first attachment
portion and said second attachment portion, said body comprising a
flexible planar or linear element, oriented perpendicular to the
axis of reciprocation of said compressor;
[0012] the first attachment portion of each said suspension element
being connected with said compressor part of greater mass, and the
second attachment portion of each said element being fixed to one
part of said hermetic housing, such that substantially the entire
weight of said compressor hangs from said second attachment
portions.
[0013] To those skilled in the art to which the invention relates,
many changes in construction and widely differing embodiments and
applications of the invention will suggest themselves without
departing from the scope of the invention as defined in the
appended claims. The disclosures and the descriptions herein are
purely illustrative and are not intended to be in any sense
limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side elevation in cross-section of a
refrigeration compressor including a linear compressor suspended in
a housing. The compressor is suspended in the housing at each end
by a suspension element according to a preferred embodiment of the
present invention.
[0015] FIG. 2 is a perspective view of a suspension element
according to a first embodiment of the present invention.
[0016] FIG. 3 is a side elevation, with partial cutaway, showing a
pair of suspension elements as illustrated in FIG. 2 assembled
together.
[0017] FIG. 4 is a side elevation of a suspension assembly for one
end of the compressor, including a pair of suspension elements
assembled together, a clamp for clamping the elements to the
compressor and locating components for securing the suspension
elements within the compressor housing. The locating components and
clamp are shown in cross-section through the centre line of the
compressor. The suspension elements are shown in partial
cutaway.
[0018] FIG. 5 is a perspective view of the clamp illustrated in the
assembly of FIG. 4.
[0019] FIG. 6 is a perspective view of a locating component in
accordance with the assembly of FIG. 4.
DETAILED DESCRIPTION
[0020] Referring to FIG. 1, the compressor for a vapour compression
refrigeration system includes a linear compressor 1 supported
inside a housing 2. Typically the housing 2 is hermetically sealed
and includes a gases inlet port 3 and a compressed gases outlet
port 4. Uncompressed gases flow within the interior of the housing
surrounding the compressor 1. These uncompressed gases are drawn
into the compressor during intake stroke, compressed between the
piston crown 14 and valve plate 5 on the compression stroke, and
expelled through discharge valve 6 into a compressed gases manifold
7. Compressed gases exit the manifold 7 to the outlet port 4 in the
shell through a flexible tube 8. To reduce the stiffness effect of
discharge tube 8 the tube is preferably arranged as a loop or
spiral transverse to the reciprocating axis of the compressor. The
intake to the compression space may be through the piston (with an
aperture and valve in the crown) or through the head, divided to
include suction and discharge manifolds and valves.
[0021] The illustrated linear compressor 1 has, broadly speaking, a
cylinder part and a piston part connected by a main spring. The
cylinder part includes cylinder chassis 10, cylinder head 11, valve
plate 5 and a cylinder liner 12. It also includes stator parts 15
for a linear electric motor. An end portion 18 of the cylinder
part, distal from the head 11, mounts the main spring relative to
the cylinder part. In the illustrated embodiment the main spring is
a combination of coil spring 19 and flat spring 20.
[0022] The piston part includes a hollow piston 22 with sidewall 24
and crown 14. A rod 26 connects between the crown 14 and a
supporting body 30 for linear motor armature 17. The rod 26 has a
flexible portion 28 approximately at the centre of the hollow
piston 22. The linear motor armature 17 comprises a body of
permanent magnet material (such as ferrite or neodymium) magnetised
to provide one or more poles directed transverse to the axis of
reciprocation of the piston within the cylinder liner. An end
portion 32 of armature support 30, distal from the piston 22, is
connected with the main spring 19, 20.
[0023] This briefly describes a linear compressor of a type for
which the suspension element and arrangement of the present
invention is useful. However it will be appreciated that the
usefulness of the suspension arrangement of the present invention
is not restricted to linear compressors of the type and
configuration illustrated. It is generally applicable where
operation of the linear compressor results in the relative
reciprocation of the centre of mass of the piston carrying part and
the centre of mass of the cylinder part along the linear axis.
[0024] The suspension element and arrangement of the present
invention is most usefully applied to support the heavier of the
relatively moving assemblies, typically the cylinder part assembly.
The lighter assembly is supported by the heavier. For example the
piston part assembly is supported by the cylinder part assembly. In
the preferred embodiment, as illustrated in FIG. 1, a suspension
element is provided at each extreme end of the compressor. This is
so that the element can have the longest possible span between the
housing and the compressor, with connection points to the
compressor being the axis of relative reciprocation of the centres
of mass of the two main assemblies.
[0025] Referring to FIG. 2, the suspension element of the preferred
embodiment of the present invention has a linear or planar flexible
element 40 that extends between the compressor housing and the
compressor. Essentially the compressor hangs from an upper support
bracket, suspended on the linear or planar element 40. In the
preferred embodiment the linear or planar flexible element 40
comprises a thin polymer sheet material. This sheet material may
encapsulate one or more reinforcing wires or fibres. For example
the material of the element may comprise a pair of Mylar plastic
sheets laminated together with a reinforcing fibre between them.
The reinforcing fibre may for example be an aramid fibre yarn or a
narrow gauge multiple strand metallic wire.
[0026] The important qualities of the element 40 are low bending
stiffness and low mass.
[0027] In the preferred form of suspension element illustrated in
FIG. 2 the flexible element 40 is integrated into an overall
component to provide for simplified assembly to the compressor and
location within the compressor shell. Each suspension element
includes the flexible element 40, fixed at one end into a rigid
locating member 42. The locating member 42 may for example be
moulded from a plastic material, and preferably is moulded over a
rolled edge of the flexible element 40 such that the flexible
element 40 is securely fixed within the member 42. The locating
member 42 is configured to locate within the refrigeration
compressor housing. Preferably the member 42 is to locate in a
support component that has been previously secured to the inner
surface of the housing. A suitable support component 44 is
illustrated in FIG. 6.
[0028] The applicants intend to provide an additional suspension
element upwards as illustrated in FIG. 2. The pair of suspension
elements allow the compressor to be provided in opposite
orientations, such that the same compressor may be fixed on a base
platform, or may be inverted and fixed to the ceiling of a machine
compartment of a refrigerator.
[0029] For this purpose it is preferred that an assembly comprising
a pair of suspension elements may be completed and assembled to the
compressor, the compressor may be subsequently fitted into one half
of the refrigeration compressor housing, with the other half of the
refrigeration compressor housing subsequently secured in place. The
suspension element of FIG. 2 is specifically adapted to this
purpose. Of course other configurations are possible in which case
one or more of the additional features identified below may be
omitted.
[0030] In the preferred form of suspension element a support leg 46
extends from one end of the locating member 42. The support leg 46
is substantially parallel with the plane of flexible element 40.
The locating member 42 includes at its other end a flange 48. The
flange 48 serves to further locate the member 42 in the receptacle
45 of support component 44, and also provides a recess for
receiving the free end of the leg 46 of the second suspension
element component of the assembly. As illustrated in FIG. 3 a pair
of members 42 are thus held in a substantially rigid spaced apart
relationship by the pair of legs 46 extending between them. Each
flange 48 has a pair of recesses 50, each offset from the plane of
the flexible element 40. One recess 50 receives the free end 52 of
the leg 46 such that the suspension elements are staggered with the
planes of the flexible elements 40 spaced a small distance
apart.
[0031] A number of features of the suspension element are provided
such that the assembly uses few distinct subcomponents. Of course
alternative arrangements are possible, including where the elements
comprising the assembly are not identical components. For example a
complete component including both flexible elements, rigid locating
members and dividing support legs could be manufactured in a single
overmoulding operation, or division of the assembly into two
components could be along alternative lines.
[0032] The flexible element 40 of each suspension element
preferably includes a pair of divergent flexible members 56. The
flexible members 56 may, as illustrated, be spread apart at the
ends adjacent the rigid locating member 42 and be together at an
attachment portion 54 of the flexible element 40 which allows for
securing the flexible element to the suspended compressor.
Alternatively, not shown, the flexible members 56 may be together
at the locating member for securing to the housing and spread apart
at the attachment portion for securing to the compressor.
[0033] Division of the flexible element into two or more narrower
strips of flexible material reduces windage and the tendency for
the flexible membrane to flap as the compressor reciprocates in the
housing. Furthermore the arrangement of strips in connecting
between the compressor housing and the compressor may provide
stability to the compressor including where the suspension element
connects to the compressor at or below the centreline. It should be
noted that multiple flexible strips may be provided as individual
elements or components, or may be integrated with two or more in
the same component or assembly as is the case in the illustrated
embodiment.
[0034] The attachment portion 54 of the suspension element
preferably comprises a folded end of the flexible element 40. The
folded attachment portion 54 may thereby be secured to a suitable
attachment bracket or mounting of the compressor assembly by
sandwiching between a clamping element and the mounting. Such an
arrangement is illustrated in more detail in FIG. 4 where the
assembly of a pair of suspension elements is illustrated captured
between a pair of support components 44. In the complete compressor
the support components 44 are previously secured to the inner
surface of the compressor housing.
[0035] Attachment portions 54 are secured to mountings 64 of a
mounting bracket 72. The mounting bracket 72 is in turn secured to
the compressor, for example as illustrated in FIG. 1. The mountings
64 of mounting bracket 72 each include a seat 66 or 67 respectively
to receive the attachment portions 58. The seats 66 and 67 are
offset to match the offset between the planes of the flexible
elements 40 in the assembly of two suspension elements. The flaps
58 of attachment portions 54 are each secured against the
respective seats 66 or 67 by a clamping member 60. The clamping
member 60 is tightly fastened to the bracket 62. For example rivets
70 extend through the clamping member 60, the flap 58 of the
attachment portion 54 and the mounting 64 and draw all three
tightly together.
[0036] In the assembly of two suspension elements, with the planes
of flexible elements 40 offset, the clamping bracket 72 may
translate relative to support components 44 without the flexible
elements interfering with one another. To translate in one
direction the attachment portion 54, and respective mounting 64
pass into the open space 74 between the flexible members of the
other flexible element. In translating in the other direction the
attachment portion of this other flexible element, and its
respective mounting, pass into the open space between the flexible
members of the first flexible element.
[0037] In arrangements such as those described with reference to
FIGS. 3 and 4, where there is a suspension element provided from
both above and below the compressor, a degree of slack must be
provided so that the elements do not, between them, pull tight as
the compressor translates backward and forward in the housing. This
degree of slack will set the overall limit of axial translation in
the housing. With the compressor mounted in the housing the upper
suspension element will be under tension and the slack will be
exhibited in the lower suspension element.
[0038] It will be appreciated that arrangements having a flexible
flap suspension element extending from both above and below the
compressor are only a preferred form of the present invention. The
present invention also envisages arrangements in which suspension
elements are only provided to hang the compressor from above, in
which case the locating portion of the suspension element for
connecting to the housing may be adapted to engage with the
housing, or with a suitable support component secured to the
housing. Alternatively a complete support structure may be included
in the single suspension element, including a base member for
locating to a lower portion of the housing and a frame extending
from the base member to support the upper edge of the flexible
element from above the compressor.
[0039] It may be noted that in the suspension elements of the
present invention the flexible element is of lightweight and low
stiffness in the direction of reciprocation. It will also be noted
that in the preferred embodiment each end of the flexible element
is secured against rotation, so as to behave as a "built in" end.
With the attachment portion 54 secured to the compressor assembly
well below the centreline of the compressor assembly, the centre of
bending (as defined in our Patent Application PCT/NZ2004/000108) of
each suspension element may be in line or at least substantially in
line with the axis of the movement of the centre of mass of the
compressor assembly, in accordance with one of the inventions
disclosed in that application.
[0040] When suspension of the compressor in the housing is by a
conventional coil spring there is the disadvantage that when the
coil springs are made soft to minimise vibration along the axis of
the compressor they allow too much movement at right angles to this
axis. This can compromise robustness during transport and handling
of the compressors or the appliance in which they are fitted.
Conventional coil springs can also be noisy as in use they tend to
slide over the snubbers that locate them at each end.
[0041] In preferred applications the compressor rus at a varying
natural frequency due to the variable stiffness of the compressed
gas associated with the current running conditions. The compressor
resonant system allows the compressor to move almost sinusoidally
but there are higher order harmonics due mainly to the non linear
stiffness of the compressed gas. These higher harmonics can excite
resonance in the suspension spring. The spring element of the
present invention is very soft in the axis of reciprocation and has
little weight of its own. Accordingly the inventors expect that it
will not exhibit substantial resonance effects or be a source of
noise in the compressor.
* * * * *