U.S. patent application number 13/145910 was filed with the patent office on 2011-11-10 for compressor, in particular a radial piston compressor for carbon dioxide as a refrigerant.
This patent application is currently assigned to OBRIST ENGINEERING GMBH. Invention is credited to Martin Graz, Stefan Kross, Frank Obrist.
Application Number | 20110274575 13/145910 |
Document ID | / |
Family ID | 42107380 |
Filed Date | 2011-11-10 |
United States Patent
Application |
20110274575 |
Kind Code |
A1 |
Obrist; Frank ; et
al. |
November 10, 2011 |
COMPRESSOR, IN PARTICULAR A RADIAL PISTON COMPRESSOR FOR CARBON
DIOXIDE AS A REFRIGERANT
Abstract
A compressor, in particular a radial piston compressor, further
in particular a compressor for CO.sub.2 as a refrigerant, including
a compressor unit for compressing refrigerant and a drive shaft for
driving the compressor unit and a motor chamber bounded
substantially by a motor housing, wherein the motor chamber has a
fluid connection to a suction gas side, in particular a suction gas
chamber, of the compressor by means of a fluid connection formed at
least partially in the drive shaft, wherein at least one device for
accumulating oil is arranged in the fluid connection.
Inventors: |
Obrist; Frank; (Lauterach,
AT) ; Graz; Martin; (Lustenau, AT) ; Kross;
Stefan; (Dornbirn, AT) |
Assignee: |
OBRIST ENGINEERING GMBH
Lustenau
DE
GEA BOCK GMBH
Frickenhausen
DE
|
Family ID: |
42107380 |
Appl. No.: |
13/145910 |
Filed: |
January 22, 2010 |
PCT Filed: |
January 22, 2010 |
PCT NO: |
PCT/EP2010/050737 |
371 Date: |
July 22, 2011 |
Current U.S.
Class: |
418/55.1 |
Current CPC
Class: |
F04B 27/109 20130101;
F25B 2309/061 20130101; F04B 39/04 20130101; F04C 23/008 20130101;
F04B 39/0094 20130101; F25B 31/023 20130101; F04B 27/0531 20130101;
F04B 53/08 20130101; F04C 29/045 20130101; F25B 31/002 20130101;
F04C 23/02 20130101; F04B 39/06 20130101 |
Class at
Publication: |
418/55.1 |
International
Class: |
F01C 1/02 20060101
F01C001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2009 |
DE |
10 2009 006 040.5 |
Claims
1. A compressor, in particular radial piston compressor, more
particularly a compressor for CO.sub.2 as refrigerant, which
compressor comprises a compressor unit for compressing refrigerant
and comprises a drive shaft for driving the compressor unit and
also comprises a motor chamber delimited substantially by a motor
housing, the motor chamber being fluidically connected to a suction
gas side, in particular suction gas chamber, of the compressor via
at least one fluid connection formed at least partially in the
drive shaft, wherein at least one device for causing a build-up of
oil is arranged in the fluid connection.
2. The compressor as claimed in claim 1, wherein the at least one
device for causing a build-up of oil is formed so as to maintain an
uninterrupted fluid connection.
3. The compressor as claimed in claim 1, wherein the fluid
connection comprises an in particular cylindrical first axial
cutout which is formed in the axial direction in the drive
shaft.
4. The compressor as claimed in claim 1, wherein the fluid
connection is fluidically connected to at least one in particular
cylindrical radial cutout which is formed in the radial direction
in the drive shaft.
5. The compressor as claimed in claim 3, wherein the fluid
connection has a tubular element whose outer diameter is smaller
than the diameter of the axial cutout, wherein the tubular element
is arranged parallel to or concentrically with respect to the axial
cutout and projects at least partially into the latter.
6. The compressor as claimed in claim 5, wherein the tubular
element is fluidically connected to the suction gas side, in
particular suction gas chamber.
7. The compressor as claimed in claim 3, wherein the fluidic
connection comprises a second, in particular cylindrical axial
cutout which is formed in the axial direction in the drive shaft
and whose cross section, in particular diameter, is smaller than
that of the first axial cutout, and in that the second axial cutout
is fluidically connected at one end thereof to the first axial
cutout and which opens out at its second end into the suction gas
side.
8. The compressor as claimed in claim 7, wherein the second axial
cutout is fluidically connected at one end thereof to the first
axial cutout by means of at least one radial cutout, preferably
radial bore, which extends radially relative to said first axial
cutout.
9. The compressor as claimed in claim 1, wherein the fluid
connection has a point of reduced cross section.
10. The compressor as claimed in claim 9, wherein the point of
reduced cross section comprises a nozzle or an orifice or a point
of reduced material cutout or a flap.
11. The compressor as claimed in claim 9, wherein the point of
reduced cross section is arranged in the second axial cutout and/or
in the radial cutout.
12. The compressor as claimed in claim 9, wherein the point of
reduced cross section has an adjustable, in particular controllable
or regulable cross section.
13. The compressor as claimed in claim 1, wherein the fluid
connection comprises at least one further in particular
reservoir-like or basin-like cutout which is arranged in the drive
shaft and which is designed to cause a build-up of the oil.
14. The compressor as claimed in claim 1, wherein an oil overflow
is provided which determines the amount of oil built up or
accumulated.
15. The compressor as claimed in claim 14, wherein the oil overflow
comprises a tubular element which is arranged in a radial cutout in
the drive shaft and which projects into the fluid connection
between the motor chamber and the suction gas side.
Description
[0001] The present invention relates to a compressor, in particular
a radial piston compressor, more particularly a compressor for
CO.sub.2 as refrigerant, as per the preamble of patent claim 1.
[0002] Compressors, in particular compressors for refrigerant such
as for example R134a, R404A, R507, R407c, R22 or R744 (CO.sub.2),
have become indispensible in this day and age and are used inter
alia in the field of mobile cooling and air conditioning, such as
for example the air-conditioning of passenger motor vehicles and
utility vehicles, the air-conditioning of buses and trains and
in-transit cooling, and also in the static cooling of foodstuffs,
in refrigerated warehouses or in the field of medical technology.
Such compressors are nowadays essential also in the field of air
conditioning for buildings.
[0003] Examples of compressors which are used in some of the fields
mentioned are known from the applicant's semi-hermetics catalog. In
particular, reciprocating piston compressors having two, four, six
and eight cylinders, which have swept volumes of approximately 62
cm.sup.3-3,215 cm.sup.3, are known from said catalog.
[0004] Furthermore, DE 103 56 373 A1 discloses a compressor in the
form of a radial piston compressor which comprises a compressor
unit for compressing refrigerant and comprises a drive shaft for
driving the compressor unit. In the compressor according to DE 103
56 373 A1, the central points of the pistons are arranged in a
common plane through which the drive shaft extends perpendicularly,
or to which a central axis extending in the longitudinal direction
of the drive shaft is perpendicular.
[0005] Also known from the prior art are compressors, in particular
radial piston compressors, whose drive shaft is operatively
connected to an electric motor, the motor being delimited
substantially by a motor housing which in its interior defines a
motor chamber, the motor chamber being fluidically connected via a
bore in the drive shaft to a suction gas chamber from which the
refrigerant to be compressed is sucked. To cool the motor, a
partial mass flow of the suction gas from the suction gas chamber
is supplied to the motor chamber via a duct and is supplied to the
suction gas volume again via the abovementioned bore in the drive
shaft. On account of the flow conditions, the partial mass flow
conducted back to the suction gas volume contains oil. Said oil is
used for lubricating bearings or the like. Depending on the
operating state of the compressor, however, a situation may arise
(for example at low rotational speeds) in which optimum lubrication
does not take place.
[0006] Taking the prior art discussed above as a starting point, it
is an object of the present invention to specify a compressor in
which good lubrication is ensured for wide operating ranges.
[0007] Said object is achieved by means of a compressor having the
features of patent claim 1, wherein further features and advantages
of the invention may be gathered from the following description of
the figures and from the subclaims.
[0008] The invention will be described by way of example below with
reference to the appended drawings on the basis of possible
embodiments. In the drawings:
[0009] FIG. 1 shows a first embodiment of a compressor according to
the invention in a partially sectional illustration in a horizontal
installation situation;
[0010] FIG. 2 shows the embodiment as per FIG. 1 in a vertical
installation situation;
[0011] FIG. 3 shows a detailed illustration of a detail from FIGS.
1 and 2;
[0012] FIG. 4 shows a detailed illustration of a second possible
embodiment of a compressor according to the invention, similar to
the illustration in FIG. 3; and
[0013] FIG. 5 shows a detailed illustration of a third possible
embodiment of a compressor according to the invention, similar to
the illustration in FIG. 3.
[0014] As can be seen for example from FIGS. 1 and 2, the first
embodiment of a compressor 10 according to the invention has a
compressor unit 12 and a motor unit 14. The motor unit 14 has a
motor housing 16 which, in the first embodiment, delimits not only
a motor chamber 18 but also, in part, the compressor unit 12.
Arranged in the motor chamber 18 in addition to an electric motor
is a drive shaft 22 via which the motor 20 is operatively connected
to the compressor unit 12. In the described first embodiment, the
compressor unit 12 has six pistons 24 which are arranged in the
radial direction. The pistons 24 are arranged in a common plane
spanned by the piston longitudinal axes which extend in the piston
longitudinal direction, which plane is perpendicular to the drive
shaft 22. It is pointed out at this juncture that a different
number of pistons 24 is self-evidently also conceivable, wherein
the number of pistons is determined in particular by the technical
requirements of the user of the compressor 10 (swept volume and
desired compression power).
[0015] The compressor unit 12 is provided for the compression of
refrigerants, wherein common refrigerants such as for example
R134a, R404A, R507, R407c, R22 or preferably R744 (CO.sub.2) are
conceivable as refrigerant. The refrigerant passes, on a suction
gas side, via a suction gas chamber 26 arranged at the suction gas
side into cylinder bores 28 (which are formed in the radial
direction) of the compressor 10, in which cylinder bores the
pistons 24 are arranged in a reciprocating fashion. The compression
of the refrigerant is realized by means of a movement of the
pistons 24 in the radial direction. When the piston 24 has arrived
in an upper position in the cylinder bore 28, that is to say the
piston 24 has arrived in a radially outwardly facing position, the
refrigerant which is then compressed is discharged into a
compressed-gas chamber 30 which is arranged at the high-pressure
side and from which the compressed refrigerant is provided to a
refrigerant circuit assigned to the compressor 10.
[0016] The compressor 10 also has, in addition to the compressor
unit 12 and the motor unit 14, an electrical terminal box 32 which
is fastened to the motor housing 16 of the compressor 10 by means
of fastening elements for example in the form of screws. The stator
of the electric motor 20 is positioned in the motor housing 16 and
may be fixed to the latter for example by means of screws.
[0017] The electrical terminals for the compressor 10, in
particular the terminals for the current or voltage supply to the
electric motor 20, are arranged in the terminal box 32. Also
contained in the terminal box 32 are electronic motor protection
components to which components such as for example a heat
protection thermostat 38 can also be connected. For a supply of
electricity, the terminal box 32 has a plurality of cable inlets 36
which, as illustrated in FIG. 1, may be closed off when not being
used, for example by means of closure elements. The cable inlets 36
illustrated are preferably pre-punched, originally closed cutouts
which are first opened by being pushed in. Therefore, no separate
components are required; these are rather regions of the outer
contour of the terminal box 32 which have been pre-punched such
that they can be opened more easily.
[0018] On account of the high pressures of the refrigerant (for
example CO.sub.2), a heat protection thermostat 38 is preferably
not arranged so as to be in direct contact with the refrigerant but
rather arranged in the motor housing 16 so as to be separate from
the refrigerant. In this way, the heat protection thermostat 38 has
only an indirect thermal connection to the refrigerant. The heat
protection thermostat 38 may be connected to elements in the
terminal box 32 by means of a cable 39, for example through a cable
inlet 36.
[0019] For the lubrication of the compressor 10, lubricant in the
form of oil 41 is situated in the compressor 10. The oil 41 is
stored in the motor chamber 18, wherein the oil 41 is used not only
for lubricating parts of the compressor 10 arranged in the motor
chamber 18 but rather also for lubricating parts of the compressor
10 arranged outside the motor chamber 18. In the region of the
motor chamber 18, it is necessary to lubricate bearings 40, 42, 44
(front bearing bush 42, rear bearing bush 44 and bearing 40 for
mounting the drive shaft 22 in the motor housing 16). Outside the
motor chamber 18, the movable parts of the compressor unit 12, in
particular the pistons 24, require corresponding lubrication.
[0020] The compressor 10 has a fluid connection 45 between the
motor chamber 18 and the suction gas side (suction gas chamber 26),
which fluid connection, aside from returning the partial mass flow
which cools the motor, also serves for the lubrication of the
bearings 40, 42, 44. The fluid connection 45 is formed to a large
extent in the drive shaft 22 and consists inter alia of an axial
cutout formed in the drive shaft 22 in the manner of a bore 46
extending in the axial direction. Furthermore, the fluid connection
45 comprises four radial cutouts arranged in the radial direction
in the drive shaft 22, said radial cutouts taking the form of a
first, a second, a third and a fourth radial bore 48, 50, 52, 54
which are fluidically connected to the bore 46. The first radial
bore 48, which extends through the entire drive shaft 22 so as to
have two openings to the motor chamber 18, serves for receiving the
partial mass flow which also contains oil or oil mist. The second,
third and fourth radial bores 50, 52, 54 are provided for the
lubrication of the bearings 40, 42, 44. Oil 41 can emerge through
said bores in the radial direction into the bearing points to be
lubricated. The outflow of the oil 41 in the radial direction is
assisted by the rotational movement of the drive shaft 22 and the
resulting centrifugal forces generated.
[0021] To permit cooling of the motor, the suction gas chamber 26,
as already mentioned above, is connected to the motor chamber 18 by
means of a fluid connection 45. The fluid connection 45 has inter
alia the first radial bore 48, which serves as an inlet for the
partial mass flow, and the bore 46 which is fluidically connected
to said first radial bore. For the lubrication of the bearing 44
(second bearing bush), the fluid connection also has a radial bore
54 which is fluidically connected to the bore 46. The radial bore
54 is fluidically connected to a second axial cutout in the form of
a second bore 56 which extends in the axial direction in the drive
shaft 22, which second bore has a cross section smaller than the
cross section of the bore 46 and which second bore is fluidically
connected, at its end facing away from the motor chamber 18, to the
suction gas chamber 26. Arranged at the suction-gas-side end of the
bore 56 is a point of reduced cross section in the form of a nozzle
58 which limits and defines the inflow of oil into the suction gas
chamber 26. According to requirements, the nozzle 58 is selected at
the factory and the corresponding cross section or the
corresponding throughflow rate is adapted to the design
requirements.
[0022] It is additionally possible, in alternative embodiments of
the invention, for the oil inflow to be regulated by means of the
bore cross section of the radial bore 54 or of the axial bore 56,
for example by means of the bore cross section itself or by means
of a constriction arranged in the bore 54 or 56, or an orifice or a
flap, in addition to the nozzle 58 or instead of the nozzle 58. The
orifice or flap may be designed so as to be non-adjustable or
adjustable, such that by means thereof, the oil flow or the
lubrication via the suction gas chamber 26 can be controlled or
regulated as a function of external parameters and if appropriate
also as a function of parameters of the compressor itself.
Furthermore, it is possible for the nozzle 58 to be provided with a
variable nozzle cross section and/or an upstream valve which opens
or closes on a predetermined or variable clock cycle such that the
oil quantity supplied to the suction gas chamber 26 can be
regulated or controlled.
[0023] The two axial cutouts 46 and 56 are formed in the drive
shaft 22 preferably axially parallel to one another with a radial
spacing, and preferably in the manner of axially parallel
bores.
[0024] To ensure a reliable supply of oil in particular to the
bearings 42, 44, a device for causing a build-up of oil, in the
form of a tubular element or tube 60, is arranged in the fluid
connection 45, which device serves to ensure that sufficient oil 41
is supplied to the nozzle 58 and to the radial bores 52, 54. Aside
from the function of causing a build-up, the tube 60, on account of
its being fluidically connected, at its side facing away from the
motor chamber, to the suction gas volume, serves to ensure the
return of the partial mass flow from the motor into the suction gas
chamber. An oil overflow device in the form of a tube 61 which is
pressed into the drive shaft 22 and which extends into the axial
bore 46 serves for the discharge of excess built-up oil 41. It
should however be noted that the tube 60 is provided not for the
lubrication of the compressor unit 12 but rather merely as an oil
overflow in the event that too large an oil quantity has built up.
The device for causing a build-up of oil, in the form of the tube
60, is designed to cause a build-up of oil 41 while maintaining an
uninterrupted fluid connection. It should be noted that the tube 60
has an outer diameter smaller than the diameter of the axial bore
46, and that the tube 60 is arranged concentrically with respect to
the axial bore 46 and projects into the latter. As an alternative
to this, a non-concentric, parallel arrangement with respect to the
bore is also conceivable.
[0025] The compressor 10 illustrated in FIG. 1 is illustrated in a
vertical installation situation in FIG. 2, wherein in this
installation situation, the lubricant in the form of the oil 41
covers the radial cutout (radial bore 48). Operation is possible
even with a covered radial cutout, wherein it would also be
conceivable for the radial bore 48 to be arranged above the oil
level, such that again, oil mist rather than oil 41 is sucked
in.
[0026] Additionally or alternatively to the tube 60 as a device for
causing a build-up of oil, it is also conceivable for an orifice 62
(in this regard cf.
[0027] FIG. 4) arranged for example in the drive shaft 22, and/or
reservoir-like or basin-like cutouts 64 (in this regard, cf. FIG.
5) which extend in the radial direction, to be provided in the
fluid connection 45 between the motor chamber 18 and the suction
gas side or suction gas chamber 26 in order to cause a build-up of
oil 41. As illustrated in FIG. 5, the reservoir-like cutouts 64 are
formed in the region of the radial bores 52, 54. It is
self-evidently also conceivable for reservoir-like cutouts of said
type to also be provided in the region of the further cutouts/bores
arranged in the radial direction in the drive shaft. The
centrifugal forces arising as the drive shaft 22 rotates ensure a
reliable supply of oil to the cutouts 64.
[0028] Even though the invention has been described on the basis of
embodiments with a certain combination of features, the invention
however also encompasses further combinations as specified in
particular but not exhaustively by the subclaims.
* * * * *