U.S. patent application number 12/310761 was filed with the patent office on 2010-01-14 for reciprocating piston compressor.
This patent application is currently assigned to BSH Bosch und Siemens Hausgerate GmhH. Invention is credited to Marco Giacchi, Thorsten Kusnik, Jan-Grigor Schubert.
Application Number | 20100008801 12/310761 |
Document ID | / |
Family ID | 38596318 |
Filed Date | 2010-01-14 |
United States Patent
Application |
20100008801 |
Kind Code |
A1 |
Giacchi; Marco ; et
al. |
January 14, 2010 |
Reciprocating piston compressor
Abstract
A compressor including a cylinder, the cylinder delimiting a
compressor chamber having a circular cross-section and the cylinder
having a longitudinal axis and including a front wall, the front
wall of the cylinder having inlet and outlet openings for passage
therethrough of a medium to be compressed; and a reciprocating
piston disposed in the compressor chamber, the reciprocating piston
being reciprocable within the compressor chamber in a movement that
includes a dead center position and having a pair of opposed ends
with one end being more proximate to the front wall of the cylinder
than the other opposed end and the reciprocating piston having an
expulsion projection on its one end, the expulsion projection
entering the outlet opening in a dead center position of the
reciprocating piston, the longitudinal axis of the cylinder
extending through the outlet opening.
Inventors: |
Giacchi; Marco;
(Waldstetten, DE) ; Kusnik; Thorsten; (Bachingen,
DE) ; Schubert; Jan-Grigor; (Senden, DE) |
Correspondence
Address: |
BSH HOME APPLIANCES CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
100 BOSCH BOULEVARD
NEW BERN
NC
28562
US
|
Assignee: |
BSH Bosch und Siemens Hausgerate
GmhH
Munchen
DE
|
Family ID: |
38596318 |
Appl. No.: |
12/310761 |
Filed: |
August 7, 2007 |
PCT Filed: |
August 7, 2007 |
PCT NO: |
PCT/EP2007/058184 |
371 Date: |
August 24, 2009 |
Current U.S.
Class: |
417/416 ;
417/520 |
Current CPC
Class: |
F04B 35/045 20130101;
F04B 39/1073 20130101; F04B 39/1086 20130101; F04B 39/1066
20130101 |
Class at
Publication: |
417/416 ;
417/520 |
International
Class: |
F04B 35/04 20060101
F04B035/04; F04B 7/04 20060101 F04B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 7, 2006 |
DE |
10 2006 042 015.2 |
Claims
1-12. (canceled)
13. A compressor comprising: a cylinder, the cylinder delimiting a
compressor chamber having a circular cross-section and the cylinder
having a longitudinal axis and including a front wall, the front
wall of the cylinder having inlet and outlet openings for passage
therethrough of a medium to be compressed; and a reciprocating
piston disposed in the compressor chamber, the reciprocating piston
being reciprocable within the compressor chamber in a movement that
includes a dead center position and having a pair of opposed ends
with one end being more proximate to the front wall of the cylinder
than the other opposed end and the reciprocating piston having an
expulsion projection on its one end, the expulsion projection
entering the outlet opening in a dead center position of the
reciprocating piston, the longitudinal axis of the cylinder
extending through the outlet opening.
14. The compressor according to claim 13 wherein the inlet opening
is formed with a noncircular cross-section wherein the dimensions
of the non-circular cross-section are greater in the peripheral
direction of the cylinder than in the radial direction of the
cylinder.
15. The compressor according to claim 14 wherein the inlet opening
is formed with a cross-section in the form of an arc.
16. The compressor according to claim 13 wherein the compressor is
formed with a plurality of inlet openings distributed about the
outlet opening.
17. The compressor according to claim 16 wherein the inlet openings
are distributed along an arc.
18. The compressor according to claim 15 wherein the arc extends
over an angle of less than 180.
19. The compressor according to claim 13 and further comprising a
first shut-off body wherein the first shut-off body is forced
against the inlet opening by a first flat spring disposed in the
compressor chamber.
20. The compressor according to claim 19 wherein the first flat
spring is fastened to a point on the front wall disposed oppositely
from the inlet opening.
21. The compressor according to claim 20 wherein the first flat
spring has an opening through which the longitudinal axis of the
cylinder extends.
22. The compressor according to claim 15 and further comprising a
second shut-off body wherein the second shut-off body is forced
against the outlet opening by a second flat spring disposed on the
exterior of the front wall.
23. The compressor according to claim 19 wherein the first flat
spring and the second flat spring are each fastened to the front
wall by at least one rivet.
24. The compressor according to claim 15 and further comprising a
linear motor configured for driving piston movement.
Description
[0001] The present invention relates to a compressor with a
cylinder, which contains a compressor chamber having a circular
cross-section, in which a reciprocating piston can be moved to and
fro. Inlet and outlet openings for a medium to be compressed are
both frequently arranged on a front wall of the cylinder. To be
able to provide the openings with as large a diameter as possible
in relation to the diameter of the front wall, they are mostly
arranged on different sides of an imaginary center plane which
diametrically crosses the front wall.
[0002] To achieve a high degree of efficiency of the compressor,
the dead volume thereof has to be as minimal as possible. It is
thus known to provide a reciprocating piston compressor with a
projection on the surface of the piston which faces the front wall,
said projection engaging in the outlet opening on the top dead
center of the piston in order to expel medium contained therein
from the compressor chamber as thoroughly as possible.
[0003] To ensure that the projection of the piston can reliably
engage in the outlet opening, the piston in the compressor chamber
must not be rotatable about the longitudinal axis thereof. This
presents no problem in the case of a conventional reciprocating
piston which is driven by a rotating motor by way of a crank gear.
With newer compressor models, like the linear compressor known from
U.S. Pat. No. 6,505,032 B2 for instance, a rotation of the piston
about the longitudinal axis is not ruled out. If such a rotatable
piston is provided with a projection in the afore-described manner,
there is a danger of the projection no longer entering the outlet
opening once the piston has rotated and instead striking the front
wall of the cylinder and thereby damaging the compressor.
[0004] The object of the invention is to specify a compressor,
which achieves a high degree of efficiency without having to
exclude from the design a rotation of the piston in the compressor
chamber about the longitudinal axis thereof.
[0005] The object is achieved in that in the case of a compressor
with a cylinder, in which a compressor chamber with a circular
cross-section is formed and inlet and outlet openings for a medium
to be compressed are formed in a front wall of the cylinder, and
with a reciprocating piston which can be moved to and fro in the
compressor chamber, said reciprocating piston having an expulsion
projection on its surface facing the front wall, said expulsion
projection engaging in the outlet opening in a dead center position
of the piston, and the longitudinal axis of the cylinder runs
through the outlet opening. The central axis is to be understood as
a longitudinal axis.
[0006] In order to realize a large cross-section in the inlet
opening despite the central positioning of the outlet opening, the
latter preferably has a non-circular cross-section, the dimensions
of which are greater in the peripheral direction of the cylinder
than in the radial direction.
[0007] The inlet opening can in particular have a cross-section in
the form of an arc.
[0008] Alternatively, a plurality of inlet openings distributed
about the outlet opening may be provided. These are also
expediently distributed along an arc.
[0009] The arc is expediently concentric in respect of the
longitudinal axis. It preferably extends over an angle of less than
180.degree.. The latter is particularly significant in order to be
able to shut off the whole inlet cross-section using a single
shut-off body.
[0010] Such a shut-off body is preferably forced against the inlet
opening by means of a first flat spring arranged in the compressor
chamber.
[0011] To keep the bending load of the flat spring to a minimum, it
is expedient to make this as long as possible in relation to the
radial dimensions of the compressor. It is particularly expedient
here for the flat spring to be fastened to a point on the front
wall which is diametrically opposite to the inlet opening.
[0012] To prevent the flat spring from shutting off the outlet
opening, it is preferably provided with an opening, through which
the longitudinal axis of the cylinder runs.
[0013] A second shut-off body is preferably forced against the
outlet opening by means of a second flat spring arranged on the
exterior of the front wall.
[0014] The assembly of the compressor is simplified if the first
and second flat spring are fastened to the front wall by means of
at least one common rivet. Each flat spring is preferably held by
at least two rivets in order to reduce the rotation of the flat
spring, which could result in the shut-off body no longer correctly
covering the assigned opening.
[0015] Further features and advantages of the invention result from
the description of exemplary embodiments which follows with
reference to the appended figures, in which;
[0016] FIG. 1 shows a perspective view of a linear compressor
according to the invention;
[0017] FIG. 2 shows an exploded view of parts of the compressor in
FIG. 1; and
[0018] FIG. 3 shows a section through the cylinder of the
compressor in FIG. 1.
[0019] FIG. 1 shows an exemplary design of a linear compressor for
a refrigerator, which represents a preferred use of the invention.
The linear compressor has a stiff, approximately U-shaped frame
seen from the top view, which is composed of two flat wall pieces 1
and an arc 2. A first membrane spring 3 is clamped between front
sides of the arc 2 which face one another and two wall pieces 1, a
second membrane spring 4 of the same type as membrane spring 3 is
fastened to front sides of the wall pieces 1 which face away from
the arc 2.
[0020] The membrane springs 3, 4 punched from spring steel sheet
each have four spring arms 5, which extend in a zigzagged fashion
from the wall pieces 1 to a central section 6, with which they
coincide. The central section 6 has two bores in each instance, two
exterior, upon which a permanently magnetic oscillating body 8 is
suspended with the aid of screws or rivets 7 and a central bore,
through which a piston rod 10 fastened to the oscillating body 8,
e.g. by means of screws, extends in the case of membrane spring 3.
The piston rod 10 connects the oscillating body 8 to a
reciprocating piston (not visible in the Fig) inside a cylinder 15,
which is supported by the arc 2. The refrigerant inlet and outlet
ports of the pump chamber are identified with 16 and/or 17.
[0021] Two electromagnets 9 with an E-shaped yoke and a coil wound
around the central limb of the E are each arranged between the
oscillating body 8 and the wall pieces 1 with pole shoes facing the
oscillating body 8 and are used to power an oscillating movement of
the oscillating body 8. A control circuit 37 provides the
electromagnets 9 with an alternating current, the frequency of
which is adjusted to the natural frequency of the system which can
oscillate, which is formed by the membrane springs 3, 4, the
oscillating body 8 and the reciprocating piston powered
thereby.
[0022] The cylinder 15 is, as apparent in FIG. 1, arranged in a
main body 11, in which the reciprocating piston is moved to and
fro, a valve plate 12, which forms a front wall of a compressor
chamber recessed in the main body and a cap 13, upon which the
inlet and outlet ports 16, 17 are positioned.
[0023] The design of the cylinder is more obvious with the aid of
the exploded representation in FIG. 2. The main body 11 is omitted
in FIG. 2; the outline of the compressor chamber which extends
through the main body is indicated on the valve plate 12 as a
dashed circle 14. The longitudinal axis of the compressor chamber
is indicated as a dot-dashed line. A circular outlet bore 18 is
arranged in the valve plate 12 exactly coaxially in respect of the
longitudinal axis. An arched slot extends through an angle of
approximately 120.degree. here about the outlet bore 18 and forms
an inlet opening 19 of the compressor chamber.
[0024] Further bores 20 at the edges of the valve plate 12 are
provided, in order to receive screws (not shown), with which the
valve plate 12 and the cap 13 are fastened to the main body 11. Two
further bores 21 are used to fasten two flat springs 22 and/or 23
to the valve plate 12 with the aid of rivets 24. The flat springs
22, 23 together with the inlet opening 19 and/or outlet opening 18
each form inlet and outlet valves of the compressor chamber. The
flat springs 22, 23 each have an elongated foot 25, in which holes
26 which are complimentary to the bores 21 are formed for the
rivets 24 and an elastic guide 27 protruding from the foot in
respect of the longitudinal axis.
[0025] An opening 28 is cut into the guide 27 of the flat spring
23, which, if the flat spring 23 is riveted to the valve plate 12,
releases the outlet bore 18. An end section 38 of the guide 27,
which extends in an arched manner about the opening 28, forms a
shut-off body of the inlet valve, which covers the inlet opening 19
when the flat spring 23 is relaxed.
[0026] The guide 27 of the flat spring 22 rests externally against
the outlet bore 18, with its top functioning as a shut-off body of
the outlet valve.
[0027] The interior of the cap 13 is subdivided into a low-pressure
cavity 30 and a high-pressure cavity 31 by means of an intermediate
wall 29, into which the refrigerant inlet port 16 and/or outlet
port 17 open and which communicate with the compressor chamber by
way of the inlet opening 19 and/or outlet bore 18.
[0028] The reciprocating piston designated 32 has a projection 33
which is concentric in respect of the longitudinal axis in the
perspective view in FIG. 2 of the side facing away from the
observer, the length and diameter of which correspond to the common
thickness of the valve plate 12 and the flat spring 23 and/or the
diameter of the outlet bore 18. At a top dead center of the
movement of the reciprocating piston 32, if this touches the flat
spring 23 pressed against the valve plate 12 by pressure prevailing
in the compressor chamber, the projection 33 engages in the outlet
bore 18 and ousts the remaining gas contained therein.
[0029] FIG. 3 shows a section through the main body 11 of the
compressor chamber and the reciprocating piston 32. It is apparent
that the compressor chamber 14 is surrounded by an annular cavity
34, which communicates with the compressor chamber 14 by means of a
plurality of small openings 35. The cavity 34 extends in the
longitudinal direction of the compressor chamber 14 from the top to
the bottom dead point of the reciprocating piston 32. It is
connected to the high-pressure cavity 31 of the cap by way of a
bore 36 of the valve plate 12 and is supplied with compressed
refrigerant in this way, which penetrates in small quantities
through the openings 35 into the compressor chamber 14 and thus
forms a gas cushion between the walls thereof and the reciprocating
piston 32 upon which the reciprocating piston 32 can be moved with
minimal friction in a wear-resistant fashion.
* * * * *