U.S. patent application number 11/576990 was filed with the patent office on 2008-03-27 for linear compressor cylinder and head construction.
This patent application is currently assigned to FISHER & PAYKEL APPLIANCES LIMITED. Invention is credited to Brian Robert Bonniface, Ian Campbell McGill.
Application Number | 20080075610 11/576990 |
Document ID | / |
Family ID | 36319576 |
Filed Date | 2008-03-27 |
United States Patent
Application |
20080075610 |
Kind Code |
A1 |
Bonniface; Brian Robert ; et
al. |
March 27, 2008 |
Linear Compressor Cylinder and Head Construction
Abstract
A cylinder and head assembly for a linear compressor has a
cylinder chassis (35, 11), a cylinder liner (12) open at both ends
and a valve plate (5) defining a barrier between the compression
end (37) of the cylinder liner (12) and the head space (7) defined
by the cylinder chassis. The valve (5) plate is located between an
annular shoulder (39) of the cylinder chassis (35) and an open end
of the cylinder liner (37).
Inventors: |
Bonniface; Brian Robert;
(Auckland, NZ) ; McGill; Ian Campbell; (Auckland,
NZ) |
Correspondence
Address: |
TREXLER, BUSHNELL, GIANGIORGI,;BLACKSTONE & MARR, LTD.
105 WEST ADAMS STREET, SUITE 3600
CHICAGO
IL
60603
US
|
Assignee: |
FISHER & PAYKEL APPLIANCES
LIMITED
Auckland
NZ
|
Family ID: |
36319576 |
Appl. No.: |
11/576990 |
Filed: |
November 1, 2005 |
PCT Filed: |
November 1, 2005 |
PCT NO: |
PCT/NZ05/00290 |
371 Date: |
December 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60624250 |
Nov 2, 2004 |
|
|
|
Current U.S.
Class: |
417/417 ;
417/545 |
Current CPC
Class: |
F04B 39/125 20130101;
F04B 35/045 20130101; F04B 39/122 20130101 |
Class at
Publication: |
417/417 ;
417/545 |
International
Class: |
F04B 35/04 20060101
F04B035/04; F04B 39/12 20060101 F04B039/12 |
Claims
1. A cylinder and cylinder head assembly for a linear compressor
comprising: a cylinder chassis including an inner surface defining
a cylinder head space at one end and a cylinder space extending
along an axis from said cylinder head space, said cylinder space
being at least substantially cylindrical, with an outlet from said
cylinder head space through the wall of said cylinder chassis; a
cylindrical cylinder liner, open at both ends and located within
said frame, such that the outer surface of said liner is engaged
against the cylinder space defining portion of said inner surface
of said chassis; and a valve plate defining a barrier between a
compression end of said cylinder liner and said head space, said
valve plate engaged between said cylinder chassis and said cylinder
liner to locate said valve plate against the open end of said
cylinder liner.
2. A cylinder and cylinder head assembly as claimed in claim 1,
wherein said cylinder chassis extends beyond the other end of said
cylinder liner.
3. A cylinder and cylinder head assembly as claimed claim 1,
wherein said cylinder chassis ends intermediate the ends of said
cylinder liner, to cover only a portion of the outer surface of the
cylinder liner.
4. A cylinder and cylinder head assembly as claimed in claim 3,
wherein a separate cylinder part frame is fixed over the other end
of the cylinder liner.
5. A cylinder and cylinder head assembly as claimed in claim 4,
wherein said cylinder part frame is fixed over the other end of the
cylinder liner with an interference friction fit.
6. A cylinder and cylinder head assembly as claimed claim 4,
wherein the cylinder part frame carries the stator parts of a
linear motor.
7. A cylinder and cylinder head assembly as claimed in claim 1,
wherein the valve plate is not fixed to the cylinder liner.
8. A cylinder and cylinder head assembly as claimed in claim 1,
wherein said cylinder liner is an interference fit within said
chassis and is held in place by friction.
9. A cylinder and cylinder head assembly as claimed in claim 1,
wherein said chassis includes, at a transition between said
cylinder defining part of said inner surface and said head defining
part of said inner surface, a shoulder or shoulders, and said valve
plate is pressed, on opposite sides, between said shoulder or
shoulders and the annular end of said cylinder liner.
10. A cylinder and cylinder head assembly as claimed in claim 9,
wherein the shoulder is annular.
11. A cylinder and cylinder head assembly as claimed in claim 9,
wherein the shoulder is an annular series of inwardly protruding
shoulders.
12. A cylinder and cylinder head assembly as claimed in claim 9,
wherein the shoulder presses directly against the face of the valve
plate.
13. A cylinder and cylinder head assembly as claimed in claim 9,
wherein the shoulder presses against the face of a valve plate via
an intermediate component.
14. A cylinder and cylinder head assembly as claimed in claim 13,
wherein the intermediate component is a gasket or resilient
spring.
15. A cylinder and cylinder head assembly as claimed in claim 13,
wherein a gasket is interposed between the annular end of the
cylinder liner and the valve plate.
16. A cylinder and cylinder head assembly as claimed in claim 1,
wherein the valve plate includes one or more valve members
assembled to it.
17. A cylinder and cylinder head assembly as claimed in claim 1,
wherein one or more grooves in either the inner surface of the
cylinder chassis or the outer surface of the cylinder liner define
supply passages to supply compressed gases to gas bearing ports
formed in the cylinder liner.
18. A cylinder and cylinder head assembly as claimed in claim 17,
wherein these grooves are provided in the outer surface of the
cylinder liner.
19. A cylinder and cylinder head assembly as claimed in claim 17,
wherein one or more notches are provided in the periphery of the
valve plate to define a flow path between the compressed gases
discharge space and the head and the gas bearing supply passages
defined between the chassis and the liner.
20. A linear compressor comprising a refrigeration system
compressor comprising a hermetic housing, a linear compressor
within said hermetic housing, said compressor including a cylinder
part assembly as claimed in claim 1, a piston part including a
piston for reciprocating within the cylinder defined by said
cylinder liner; and a linear electric motor for driving
reciprocating movement between the piston part and cylinder part,
with the linear compressor suspended for operation within said
hermetic housing.
21. A method of manufacturing a linear compressor, including, for
assembling the cylinder and head portion thereof, the steps of: by
differential temperature, expanding a cylinder chassis relative to
a cylinder liner part, inserting a valve plate defining barrier
into said cylinder chassis through an open end thereof, inserting
said cylinder liner part into said cylinder chassis through said
open end to engage said valve plate between an end of said cylinder
liner and said cylinder chassis to define a barrier between a
compression end of said cylinder and a head space enclosed by said
cylinder chassis, and retaining a said cylinder liner in this
position until said cylinder chassis and said cylinder liner become
engaged as said temperature differential reduces.
22. (canceled)
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 those
described in that patent application. Accordingly that application
provides a general exemplification of a 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 a
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 cylinder part and
head assemblies.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a
cylinder and cylinder head assembly with improved characteristics
with particular application to linear compressors, or to at least
provide the industry with a useful choice.
[0005] In a first aspect the invention may broadly be said to
consist in a cylinder and cylinder head assembly for a linear
compressor comprising:
[0006] a cylinder chassis including an inner surface defining a
cylinder head space at one end and a cylinder space extending along
an axis from said cylinder head space, said cylinder space being at
least substantially cylindrical, with an outlet from said cylinder
head space through the wall of said cylinder chassis,
[0007] a cylindrical cylinder liner, open at both ends and located
within said frame, such that the outer surface of said liner is
engaged against the cylinder space defining portion of said inner
surface of said chassis, and
[0008] a valve plate defining a barrier between a compression end
of said cylinder liner and said head space, said valve plate
engaged between said cylinder chassis and said cylinder liner to
locate said valve plate against the open end of said cylinder
liner.
[0009] According to a further aspect of the invention said cylinder
chassis extends beyond the other end of said cylinder liner, and
may carry, for example, stator parts of a linear motor.
Alternatively said cylinder chassis may end intermediate the ends
of said cylinder liner, to cover only a portion of the outer
surface of the cylinder liner. In that case a separate cylinder
part frame may be fixed over the other end of the cylinder liner,
for example with an interference friction fit. The cylinder part
frame may carry the stator parts of a linear motor.
[0010] According to a further aspect of the invention the valve
plate is not fixed to the cylinder liner, but alternatively it may
be, for example by solder or brazing, or by adhesive.
[0011] According to a further aspect of the invention said cylinder
liner is an interference fit within said chassis and is held in
place by friction.
[0012] According to a further aspect of the invention said chassis
includes, at a transition between said cylinder defining part of
said inner surface and said head defining part of said inner
surface, a shoulder or shoulders, and said valve plate is pressed
between said shoulder or shoulders at one side and the annular end
of said cylinder liner at its other side.
[0013] The shoulder may be annular or may be an annular series of
inwardly protruding shoulders. The shoulder may press directly
against the face of the valve plate, or may press against the face
of a valve plate via an intermediate component, such as a resilient
spring or gasket. A gasket may be interposed between the annular
end of the cylinder liner and the valve plate.
[0014] The valve plate may include one or more valve members
assembled to it.
[0015] One or more grooves in either the inner surface of the
cylinder chassis or the outer surface of the cylinder liner may
define supply passages to supply compressed gases to gas bearing
ports formed in the cylinder liner. Preferably these grooves are
provided in the outer surface of the cylinder liner, for example as
described in our PCT Application WO 02/35093. In that case one or
more notches are preferably provided in the periphery of the valve
plate to define a flow path between the compressed gases discharge
space and the head and the gas bearing supply passages defined
between the chassis and the liner.
[0016] In a further aspect the present invention may broadly be
said to consist in a refrigeration system compressor comprising a
hermetic housing, a linear compressor within said hermetic housing,
said compressor including a cylinder part assembly at least in part
defined according to one or more of the above paragraphs, a piston
part including a piston for reciprocating within the cylinder
defined by said cylinder liner, and a linear electric motor for
driving reciprocating movement between the piston part and cylinder
part, with the linear compressor suspended for operation within
said hermetic housing.
[0017] In a still further aspect the present invention may broadly
be said to consist in a method of manufacturing a linear
compressor, including, for assembling the cylinder and head portion
thereof, the steps of:
[0018] by differential temperature, expanding a cylinder chassis
relative to a cylinder liner part,
[0019] inserting a valve plate defining barrier into said cylinder
chassis through an open end thereof,
[0020] inserting said cylinder liner part into said cylinder
chassis through said open end to engage said valve plate between an
end of said cylinder liner and said cylinder chassis to define a
barrier between a compression end of said cylinder and a head space
enclosed by said cylinder chassis, and
[0021] retaining a said cylinder liner in this position until said
cylinder chassis and said cylinder liner become engaged as said
temperature differential reduces.
[0022] 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
[0023] FIG. 1 is a side elevation in cross-section of a linear
compressor with a cylinder part assembly incorporating the
invention according to one preferred embodiment.
[0024] FIG. 2 is an external perspective of the cylinder head end
portion of the cylinder part according to one preferred embodiment
of the present invention.
[0025] FIG. 3 is a cross-section side elevation of the cylinder
part portion of FIG. 2 according to one embodiment of the present
invention.
[0026] FIG. 4 is a cross-section side elevation of the cylinder
part portion of FIG. 2 according to another embodiment of the
present invention.
DETAILED DESCRIPTION
[0027] Referring to FIG. 1 the compressor for a vapour compression
refrigeration system includes a linear compressor I 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 outlet 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.
[0028] 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.
[0029] 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. The cylinder part 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 formed as a combination of coil spring 19 and flat
spring 20.
[0030] 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 has a
flexible portion 28 in approximately 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 which is distal from the piston
22 is connected with the main springs 19, 20.
[0031] The linear compressor 1 is mounted within the shell 2 on a
plurality of suspension springs to isolate it from the shell. In
use the large outer body of the linear compressor, the cylinder
part, will oscillate along the axis of reciprocation of the piston
part within the cylinder part. In the preferred compressor the
piston part is purposely kept very light compared to the cylinder
part so that the oscillation of the cylinder part is small compared
with the relative reciprocation between the piston part and
cylinder part. In the illustrated form the linear compressor is
mounted on a set of four suspension springs 31 generally positioned
around the periphery. Alternate suspension spring arrangements are
illustrated in PCT/NZ2004/000108. The ends of each suspension
spring fit over elastomeric snubbers connected with the linear
compressor 1 at one end of each spring and connected with the
compressor shell 2 at the other end of each spring.
[0032] This briefly describes a linear compressor of a type for
which the improved head assembly of the present invention is
useful. However it will be appreciated that the usefulness of the
present invention is not restricted to linear compressors of the
type and configuration illustrated. The improvement is generally
applicable.
[0033] The present invention provides a manner of manufacture of
the cylinder and cylinder head portion of the linear compressor
which reduces the parts involved and improves the reliability of
the connections, thereby improving manufacture, cost and compressor
reliability. The relevant portion of the linear compressor
illustrated in FIG. 1 is further illustrated in FIGS. 2 and 3. A
slight variation is illustrated in FIG. 4. in this manner of
manufacture the head cover is incorporated in the main chassis
component of the cylinder part 10. Preferably it is incorporated as
an integral part, for example cast integrally with the remainder of
the frame when the frame is manufactured. Thus the head 11 appears
as a cap enclosing one end of cylinder body 35.
[0034] A valve plate is secured in position within the cylinder
chassis to divide a head portion of the space therein from a
cylinder portion of the space therein. The valve plate includes at
least a discharge valve aperture, and preferably carries a
discharge valve fixed on one side.
[0035] The inner surface of the cylinder portion 35 of the chassis
is preferably cylindrical and the outer perimeter of the valve
plate is preferably circular and sized to fit closely within the
cylindrical surface.
[0036] The cylinder liner 12 has a cylindrical outer surface sized
to have an interference fit within the inner surface of cylinder
portion 35. This provides that when the cylinder liner 12 and the
cylindrical portion 35 of the cylinder chassis are at the same or
similar temperature, and the cylinder liner 12 is in place within
the cylinder chassis, the two parts are tightly engaged without
requirement for further fixing or fastening.
[0037] The periphery of valve plate 5 is engaged between the end 37
of cylinder liner 12 and the cylinder chassis. Preferably the
cylinder chassis includes an annular shoulder 39 and the shoulder
39 and end 37 of the cylinder liner directly engage opposite sides
of the periphery 38 of the valve plate. Alternatively a plurality
of shoulder portions may be provided distributed around the
periphery of the valve plate, or an intermediate spacer may be
provided between either the cylinder chassis and the valve plate 5
or between the cylinder liner 12 and the valve plate 5.
[0038] The valve plate 5 may be provided with an annular rebate 40
at periphery 38 to receive the end of cylinder liner 12.
[0039] An embodiment including an intermediate spacer is depicted
in FIG. 4. In this embodiment the spacer is not a simple
cylindrical ring or similar. Instead the spacer is an annular
spring 42. The spring 42 and valve plate 5 are both engaged between
the cylinder chassis and the cylinder liner. The annular spring 42
butts against shoulder 39 and against the periphery 38 of valve
plate 5.
[0040] A gasket 43 may be included in the assembly, for example as
illustrated in FIG. 4, sandwiched between the periphery 38 of the
valve plate 5 and the end 37 of cylinder liner 12. The gasket may
be provided in a recess 40 around the periphery of the valve
plate.
[0041] The preferred method of assembly of this part of the
compressor involves heating the cylinder chassis (which is
typically cast aluminium alloy) and then placing the valve plate
within the cylindrical cavity to butt against the shoulder 39. In
the case of the embodiment of FIG. 4 the spring spacer is inserted
first. The cylinder liner 12 is then pushed firmly into the
cylindrical cavity against the valve plate and is retained there
until the cylinder shrinks onto it. With reasonable manufacturing
tolerances it should be possible to achieve this consistently and
with very effective eventual engagement between the cylinder liner
12 and the cylinder chassis by heating the cylinder chassis to
approximately 250.degree. C. and leaving the liner at room
temperature.
[0042] This manner of manufacture can eliminate a number of parts,
the head cover and whatever bolts or fasteners would otherwise be
used to secure it, and can eliminate the potential for a leak path
through any gasket between the head and the end of the cylinder. In
the compressor of the present invention the only leak path from the
head can be back around the valve plate into the compression space
in the cylinder.
[0043] The cylinder part assembly of the present invention is
preferably applied where there is only a discharge valve in the
head assembly, with the suction valve for the compressor being
included in the crown of the piston and the gases intake occurring
through the body of the piston. However the manner of manufacture
can also be used where suction and discharge occur through the
cylinder head, but particular care would need to be taken to ensure
an adequate seal at any division between the suction side and
discharge side within the head enclosure.
[0044] The embodiment of FIG. 4, where a spring is provided
interposed between the valve plate and the cylinder chassis,
ensures an effective clamping pressure over a wider tolerance of
insertion location of the liner 12 within the cylinder frame. This
arrangement has the added advantage that the valve plate can lift
slightly if the piston collides with the valve plate in operation.
This may reduce noise from the collision and any damage to the
piston face and linkages between the piston and linear motor
armature.
[0045] The arrangement of the present invention contrasts with the
usual arrangement where the head or cover is a separate component
that is bolted or otherwise secured to the cylinder part frame,
generally with the edge of the valve plate sandwiched between the
end of the cylinder part frame and the end of the head or
cover.
* * * * *