U.S. patent application number 12/734551 was filed with the patent office on 2010-11-18 for cylinder head for piston refrigeration compressor, compression unit including such cylinder head, and piston refrigeration compressor including said compression unit.
This patent application is currently assigned to DANFOSS COMMERCIAL COMPRESSORS. Invention is credited to Patrice Bonnefoi, Pierre Ginies, Dominique Gross.
Application Number | 20100290926 12/734551 |
Document ID | / |
Family ID | 39472666 |
Filed Date | 2010-11-18 |
United States Patent
Application |
20100290926 |
Kind Code |
A1 |
Ginies; Pierre ; et
al. |
November 18, 2010 |
CYLINDER HEAD FOR PISTON REFRIGERATION COMPRESSOR, COMPRESSION UNIT
INCLUDING SUCH CYLINDER HEAD, AND PISTON REFRIGERATION COMPRESSOR
INCLUDING SAID COMPRESSION UNIT
Abstract
A cylinder head for a piston refrigeration compressor that
includes at least a first part defining a cooling-gas suction
chamber and at least a second part defining a cooling-gas discharge
chamber, the first and second parts being distinct from each other,
and the suction and discharge chambers each being intended to be
brought into communication with a compression chamber provided in
the compressor. The cylinder head includes thermal insulation means
provided between the first and second parts, the thermal insulation
means including an insulation chamber defined by the first and
second parts.
Inventors: |
Ginies; Pierre; (Sathonay
Village, FR) ; Gross; Dominique; (Jassans Riottier,
FR) ; Bonnefoi; Patrice; (Saint Didier Au Mont D'or,
FR) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
DANFOSS COMMERCIAL
COMPRESSORS
Trevoux ,Reyrieux
FR
|
Family ID: |
39472666 |
Appl. No.: |
12/734551 |
Filed: |
December 16, 2008 |
PCT Filed: |
December 16, 2008 |
PCT NO: |
PCT/FR2008/052311 |
371 Date: |
July 29, 2010 |
Current U.S.
Class: |
417/243 |
Current CPC
Class: |
F04B 2201/0801 20130101;
F04B 39/125 20130101; F04B 53/007 20130101 |
Class at
Publication: |
417/243 |
International
Class: |
F04B 23/00 20060101
F04B023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2007 |
FR |
07/09070 |
Claims
1. A cylinder head for piston refrigeration compressor, comprising
at least a first part defining a cooling-gas suction chamber and at
least a second part defining a cooling-gas discharge chamber, the
first and second parts being distinct from each other, the suction
and discharge chambers each being designed to be brought into
communication with a compression chamber provided in the
compressor, comprising thermal isolation means situated between the
first and second parts, the thermal isolation means including an
isolation chamber defined by the first and second parts wherein one
of the first and second parts comprises a tubular portion and
wherein the other part comprises a through passage, the tubular
portion being arranged to be inserted into the through passage so
as to define the isolation chamber between the outer wall of the
tubular portion and the inner wall of the through passage.
2. The cylinder head of claim 1, wherein the isolation chamber
includes a volume of air at atmospheric pressure, a volume of
cooling gas, such as CO.sub.2, at low or high pressure, a thermally
isolating material, or a combination of these different
elements.
3. The cylinder head of claim 1, wherein the tubular portion has a
groove extending over its entire periphery.
4. The cylinder head of claim 1, wherein the part comprising the
through passage has a return turned toward the inside of the
through passage, the return being arranged to cooperate with the
tubular portion.
5. The cylinder head of claim 4, wherein the return extends over
the entire circumference of the through passage.
6. The cylinder head of claim 4, wherein a gasket is situated
between the return and the tubular portion.
7. The cylinder head of claim 4, wherein the return and the tubular
portion define a groove designed to be filled with cooling gas
under operating conditions of the piston refrigeration
compressor.
8. The cylinder head of claim 1, wherein the isolation chamber is
essentially annular.
9. A compression unit for piston refrigeration compressor,
comprising a valve plate and a cylinder block, wherein it comprises
a cylinder head according to claim 1.
10. A piston refrigeration compressor comprising a compression unit
according to claim 9.
Description
[0001] The present invention concerns a cylinder head for piston
refrigeration compressor, a compression unit including said
cylinder head, and a piston refrigeration compressor including said
compression unit.
[0002] A cylinder head for piston refrigeration unit comprises, in
a known manner, a cooling-gas suction chamber and a cooling-gas
discharge chamber, the suction and discharge chambers each being
designed to be brought into communication with a compression
chamber provided in the compressor.
[0003] One drawback of this type of cylinder head lies in the fact
that the cooling gas to be compressed that is suctioned in the
suction chamber is heated by the compressed cooling gas discharged
into the discharge chamber.
[0004] This heating of the cooling gas to be compressed causes an
increase in the temperature and enthalpy of that gas, and a
decrease in its density. This decrease of the density of the
cooling gas to be compressed causes a decrease of the mass of gas
compressed by the compressor, and therefore reduced heat energy,
for a same volume of swept gas. Due to the intrinsic properties of
the cooling gas (the slope of the isentropics in the dry steam
field evolves with superheating), the compression work by unit of
mass increases following said superheating of the compressed gas,
and because of this, the energy yield of the compressor is reduced.
This results in a decrease in the compressor's performance.
[0005] Another drawback concerning piston compressors, in
particular those that must operate at high discharge pressures, is
that it is necessary to realize rigid cylinder heads so that the
pressure exerted by the cylinder head on the joints situated
between them and the valve plate, and between the valve plate and
the cylinder block, respectively, is sufficient to avoid leaks of
the cooling gas. In order to realize rigid cylinder heads for
applications with high pressures, it is necessary to have parts
with great inertia, therefore massive and heavy.
[0006] Furthermore, the increased rigidity of the cylinder head
translates to an increase of the heat conduction surfaces, and
therefore increased heating of the cooling gas.
[0007] The present invention aims to resolve these drawbacks.
[0008] The technical problem at the base of the invention therefore
consists of providing a cylinder head for piston refrigeration
compressor that has a simple and compact structure, and that makes
it possible to avoid heating of the cooling gas to be compressed by
the compressed cooling gas.
[0009] To that end, the present invention concerns a cylinder head
for piston refrigeration compressor, comprising at least a first
part defining a cooling-gas suction chamber and at least a second
part defining a cooling-gas discharge chamber, the first and second
parts being distinct from each other, the suction and discharge
chambers each being designed to be brought into communication with
a compression chamber provided in the compressor, wherein it
comprises thermal insulation means provided between the first and
second parts, the thermal isolation means including an isolation
chamber defined by the first and second parts, and wherein one of
the first and second parts comprises a tubular portion and wherein
the other part comprises a through passage, the tubular portion
being arranged to be inserted into the through passage so as to
define the isolation chamber between the outer wall of the tubular
portion and the inner wall of the through passage.
[0010] The realization of the cylinder head from two distinct parts
and the arrangement of thermal isolation means between these two
parts makes it possible to thermally isolate the suction and
discharge chambers, and therefore to avoid a thermal transfer
between them. It results from this that the cooling gas to be
compressed cannot be heated by the compressed cooling gas.
[0011] Because of this, the performance of a compressor equipped
with a cylinder head according to the invention is improved.
[0012] Making the cylinder head from two distinct parts makes it
possible to decrease the machining time of the cylinder head, use
different materials for the two parts, and also obtain precise
geometries of the isolation chamber.
[0013] Making the cylinder head using two distinct parts also makes
it possible to realize a cylinder head having a low mass. The
successive assembly of the first part defining the suction chamber
and the second part defining the discharge chamber makes it
possible to apply sufficient pressure on the surfaces of the joints
separating the low pressure zone from the high pressure zone in
order to avoid leaks of refrigerating gas.
[0014] Advantageously, the isolation chamber includes a volume of
air at atmospheric pressure, a volume of cooling gas, such as CO2,
at low or high pressure, a thermally isolating material, or a
combination of these different elements. When this isolation
chamber is situated in a cooling-gas flow zone, the gas speed
inside it is practically zero. In that case, the isolation chamber
has a thermal resistance made up of a wall of the first part, a
space for gas at practically zero speed, and a wall of the second
part. The presence of cooling gas at practically zero speed between
the walls of the first and second parts limits the convection
effect between these two walls, and therefore reduces the heat
transfer between the first and second parts. The presence of this
cooling-gas pressurized isolation chamber therefore makes it
possible to avoid heating of the cooling gas to be compressed.
[0015] According to another embodiment of the invention, the
tubular portion has a groove extending over its entire
periphery.
[0016] Preferably, the part comprising the through passage has a
return turned toward the inside of the through passage, the return
being arranged to cooperate with the tubular portion.
[0017] Advantageously, the return extends over the entire
circumference of the through passage.
[0018] According to one embedment of the invention, a gasket is
situated between the return and the tubular portion.
[0019] Advantageously, the return and the tubular portion define a
groove designed to be filled with cooling gas under operating
conditions of the piston refrigerating compressor.
[0020] Preferably, the isolation chamber is essentially
annular.
[0021] The present invention also concerns a compression unit for
piston refrigeration compressor, comprising a valve plate and a
cylinder block, wherein it comprises a cylinder head according to
the invention.
[0022] The present invention also concerns a piston refrigeration
compressor comprising a compression unit according to the
invention.
[0023] In any event, the invention will be well understood using
the description which follows, done in reference to the appended
diagrammatic drawing illustrating, as a non-limiting example, one
embodiment of a compression unit for piston refrigeration
compressor according to the invention.
[0024] FIGS. 1 and 2 are two longitudinal cross-sections.
[0025] FIG. 3 is a cross-sectional view along line III-Ill of FIG.
1.
[0026] FIG. 4 is a detailed view of FIG. 1, enlarged.
[0027] FIG. 5 is a cross-sectional view along line IV-IV of FIG.
2.
[0028] FIGS. 1 to 5 illustrate a compression unit 2 for piston
refrigeration compressor.
[0029] The compression unit 2 comprises a cylinder head 3, a valve
plate 4 and a cylinder block 5, only the cylinder 5 of which is
shown in the figures.
[0030] The cylinder head 3 comprises a first essentially
cylindrical part 6. The first part 6 is fastened on the valve plate
4. The first part 6 comprises two radial cooling gas inlets 7, 7'
and defines an essentially annular cooling-gas suction chamber 8
into which the radial inlets 7 lead.
[0031] The first part 6 comprises an axial through passage 9, the
axial passage 9 being defined by a cylindrical surface.
[0032] The first part 6 has, at its face turned toward the valve
plate 4, a radial return 11 turned toward the inside of the through
passage 9, the return 11 extending over the entire circumference of
the through passage 9.
[0033] The cylinder head 3 comprises a second part 12 axially
fastened on the first part 6 by screws 13. The assembly by screwing
of the second part 12 on the first part 6 makes it possible to have
a degree of freedom of angular orientation between the first and
second parts during their assembly.
[0034] The second part 12 defines an axial cooling-gas discharge
chamber 14 and comprises a cooling-gas discharge outlet 15 radially
opening into the discharge chamber 14.
[0035] The second part 12 comprises a first portion in flange form
16 including the discharge outlet 15 and a second tubular portion
17 inserted into the through passage 9.
[0036] As shown more particularly in FIG. 4, the tubular portion 17
comprises, at its free end, a shoulder 18 forming an axial stop
cooperating with the return 11. An annular gasket 19 is situated
between the return 11 and the tubular portion 17.
[0037] The second tubular portion 17 has an annular groove 21
provided on its outer surface.
[0038] The outer wall of the tubular portion 17 and the inner wall
of the through passage 9 define an annular thermal isolation
chamber 22.
[0039] The isolation chamber 22 includes a volume of air at
atmospheric pressure.
[0040] As shown more particularly in FIG. 4, the outer wall of the
tubular portion 17 and the inner wall of the through passage 9
define an annular groove 23 designed to be filled with cooling gas
during the operation of the compressor via a flow channel 24
connected to an annular chamber 25 defined by the valve plate 4.
This flow channel 24 is realized by a play between the free end of
the tubular portion 17 and an adapted gasket 32 situated between
the valve plate 4 and the cylinder head 3.
[0041] The presence of the annular groove 23 and of the gasket 19
makes it possible to thermally isolate the return 11 and the
tubular portion 17.
[0042] The suction 8 and discharge 14 chambers are each designed to
be brought into communication with a compression chamber 26 defined
by the cylinder 5 via the valve plate 4.
[0043] The valve plate 4 comprises a suction passage 27 leading
into the suction chamber 8 and the compression chamber 26,
respectively, and an annular valve 28 situated on the lower face of
the valve plate 4 and arranged to control the flow of cooling gas
through the suction passage 27. The annular valve 28 is kept in
closed position by a flexible element 34.
[0044] The valve plate 4 also comprises a discharge passage 29
leading into the discharge chamber 14 and the compression chamber
26, respectively, and an annular valve 31 situated on the upper
face of the valve plate 4 and arranged to control the flow of
cooling gas through the discharge passage 29. The annular valve 31
is kept in the closed position by a flexible element 35.
[0045] A second adapted gasket 33 is situated between the valve
plate 4 and the cylinder block.
[0046] It must be noted that the assembly by screwing of the first
and second parts makes it possible to precisely control the
pressure applied on the gaskets 19, 32, 33.
[0047] The operation of the compression unit 2 will now be
described.
[0048] When the piston (not shown in the figures) of the cylinder
block moves in the cylinder 5 in the direction of arrow A, a
suction force is generated in the cylinder 5. This suction force
causes a suction of the cooling gas in the suction chamber 8 via
cooling gas inlets 7. The cooling gas is then suctioned in the
compression chamber 26 via the suction passage 27 defined by the
valve plate 4. A ring 36 inserted into the suction chamber 8
advantageously makes it possible to guide the cooling gas toward
the suction passage 27, and therefore to limit the turbulence of
the flow. Moreover, this ring 36 reduces the exchange surface seen
by the cooling gas. Preferably, the ring 36 is made in a material
limiting heat conduction, such as polymers or a foam.
[0049] When the piston moves in the cylinder 5 in the direction of
arrow B, a discharge force is generated in the cylinder 5. Because
of this, the compressed and heated cooling gas is discharged into
the discharge chamber 14 of the cylinder head 3 via the discharge
passage 29 of the valve plate 4.
[0050] The cooling gas flowing in the suction chamber 8 cannot be
heated by the compressed and heated cooling gas flowing in the
discharge chamber 14 due to the presence of the isolation chamber
22, the gasket 19 and the annular groove 23, which prevent a heat
transfer between the first and second pieces 6, 12.
[0051] According to one embodiment of the invention, the cooling
gas flowing in the compression unit is CO.sub.2.
[0052] According to other embodiments of the invention, the
isolation chamber 22 could include a volume of CO.sub.2 at low or
high pressure, or a thermally isolating material.
[0053] It goes without saying that the invention is not limited
solely to the embodiment of this cylinder head described above as
an example; on the contrary, it encompasses all alternative
embodiments. In particular, the suction and discharge circuit of
the cooling gas in the cylinder head could thus be reversed. The
second part 12 could therefore define a cooling-gas suction chamber
14 connected to a suction inlet 15, and the first part 6 could
define a cooling gas discharge chamber 8 connected to two discharge
outlets 7. Moreover, the axial passage 9 could be defined by a
non-cylindrical surface, and the compression unit 2 could comprise
a single cooling gas inlet 7.
* * * * *