U.S. patent application number 13/732847 was filed with the patent office on 2013-07-11 for compression device, and a thermodynamic system comprising such a compression device.
This patent application is currently assigned to DANFOSS COMMERCIAL COMPRESSORS. The applicant listed for this patent is DANFOSS COMMERCIAL COMPRESSORS. Invention is credited to Jean BERNARDI, Patrice BONNEFOI, Xavier DURAND, Fabien GALL, Jean-Francois LE COAT.
Application Number | 20130177404 13/732847 |
Document ID | / |
Family ID | 48652712 |
Filed Date | 2013-07-11 |
United States Patent
Application |
20130177404 |
Kind Code |
A1 |
BERNARDI; Jean ; et
al. |
July 11, 2013 |
COMPRESSION DEVICE, AND A THERMODYNAMIC SYSTEM COMPRISING SUCH A
COMPRESSION DEVICE
Abstract
This compression device comprises first and second compressors
mounted in parallel, a suction line intended to be connected to an
outlet of an evaporator, first and second suction conduits arranged
for putting the suction line respectively in communication with the
admission orifices of the first and second compressors, and an oil
level equalization conduit connecting the oil pans of the first and
second compressors. The compression device further comprises an oil
separator mounted on the suction line or on the second suction
conduit, and an oil return conduit arranged for connecting an oil
outflow orifice of the oil separator to the oil pan of the first
compressor.
Inventors: |
BERNARDI; Jean; (Lyon,
FR) ; BONNEFOI; Patrice; (Saint Didier Au Mont D'Or,
FR) ; DURAND; Xavier; (Saint Didier Au Mont D'Or,
FR) ; GALL; Fabien; (Cailloux Sur Fontaines, FR)
; LE COAT; Jean-Francois; (Villefranche Sur Saone,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DANFOSS COMMERCIAL COMPRESSORS; |
Trevoux |
|
FR |
|
|
Assignee: |
DANFOSS COMMERCIAL
COMPRESSORS
Trevoux
FR
|
Family ID: |
48652712 |
Appl. No.: |
13/732847 |
Filed: |
January 2, 2013 |
Current U.S.
Class: |
415/168.1 |
Current CPC
Class: |
F04D 29/00 20130101;
F25B 31/004 20130101; F04C 23/008 20130101; F04C 2270/24 20130101;
F04C 29/02 20130101; F25B 2400/075 20130101; F04B 39/121 20130101;
F04C 23/001 20130101; F04C 28/02 20130101; F04B 39/0207 20130101;
F04B 39/0238 20130101; F25B 2400/02 20130101; F04B 49/02 20130101;
F04B 41/06 20130101 |
Class at
Publication: |
415/168.1 |
International
Class: |
F04D 29/00 20060101
F04D029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2012 |
FR |
12/50271 |
Claims
1. A compression device comprising: at least one first compressor
and one second compressor mounted in parallel, each compressor
comprising a leakproof enclosure including a low pressure portion
containing a motor and an oil pan on the one hand, and an admission
orifice opening into the low pressure portion on the other hand, a
suction line intended to be connected to an outlet of an
evaporator, a first suction conduit arranged for putting the
suction line in communication with the admission orifice of the
first compressor, a second suction conduit arranged for putting the
suction line in communication with the admission orifice of the
second compressor, and an oil level equalization conduit arranged
for putting the oil pans of the first and second compressors in
communication, wherein the compression device further comprises: at
least one oil separator mounted on the suction line or on the
second suction conduit, the oil separator comprising an oil outflow
orifice, and an oil return conduit arranged for connecting the oil
outflow orifice of the oil separator to the oil pan of the first
compressor.
2. The compression device according to claim 1, wherein the oil
separator further comprises an inlet orifice intended to be
connected to the outlet of the evaporator so as to allow the
introduction of an oil-coolant fluid mixture into the oil
separator, and a coolant fluid discharge orifice connected to at
least the admission orifice of the second compressor.
3. The compression device according to claim 2, wherein the oil
separator comprises a separation chamber, the inlet orifice and the
coolant fluid discharge orifice of the oil separator respectively
being in communication with the separation chamber.
4. The compression device according to claim 2, wherein the suction
line comprises a first connecting conduit connected to the inlet
orifice of the oil separator and intended to be connected to the
outlet of the evaporator, and a second connecting conduit arranged
for putting the coolant fluid discharge orifice of the oil
separator in communication with the first and second suction
conduits.
5. The compression device according to claim 2, wherein the second
suction conduit comprises an upstream conduit portion arranged for
putting the inlet orifice of the oil separator in communication
with the suction line, and a downstream conduit portion arranged
for putting the coolant fluid discharge orifice of the oil
separator in communication with the admission orifice of the second
compressor.
6. The compression device according to claim 1, wherein the oil
return conduit is arranged for opening into the first suction
conduit.
7. The compression device according to claim 1, wherein the oil
return conduit is arranged for opening into the oil pan of the
first compressor.
8. The compression device according to claim 1, wherein the second
suction conduit comprises restriction means arranged so as to
reduce the flow section of the coolant fluid in the second suction
conduit.
9. The compression device according to claim 1, wherein the
restriction means are arranged for maintaining pressure in the low
pressure portion of the first compressor greater than the pressure
in the low pressure portion of the second compressor when the first
and second compressors are operating simultaneously.
10. The compression device according to claim 1, wherein the first
compressor is a variable-capacity compressor.
11. The compression device according to claim 1, wherein the second
compressor is a fixed-capacity compressor.
12. The compression device according to claim 1, wherein the oil
separator is a cyclone oil separator.
13. A thermodynamic system comprising a condenser, an expansion
valve, an evaporator and a compression device according to claim 1,
connected in series.
Description
[0001] The present invention relates to a compression device, and
to a thermodynamic system comprising such a compression device.
[0002] Document FR 2 605 393 describes a thermodynamic system, and
more particularly a cooling system, comprising: [0003] a circuit
for circulating a coolant fluid successively including a condenser,
an expansion valve, an evaporator and a compression device
connected in series, the compression device comprising at least a
first compressor with a fixed capacity and a second compressor with
a fixed capacity mounted in parallel, each compressor comprising an
enclosure including a low pressure portion containing a motor and
an oil pan positioned in the bottom of the enclosure on the one
hand, and an orifice for admitting a coolant fluid, opening into
the low pressure portion on the other hand, [0004] a suction line
connected to the evaporator, [0005] a first suction conduit putting
the suction line in communication with the admission orifice of the
first compressor, [0006] a second suction conduit putting the
suction line in communication with the admission orifice of the
second compressor, [0007] a restriction member positioned in the
second suction conduit and arranged for maintaining a pressure in
the low pressure portion of the first compressor, greater than the
pressure in the low pressure portion of the second compressor when
the first and second compressors are operating simultaneously,
[0008] a flow separation device positioned between the suction line
and the first and second suction conduits, the flow separation
device being arranged in order to carry away the major portion of
the coolant fluid from the evaporator towards the first compressor,
and [0009] an oil level equalization conduit promoting transfer of
oil between both compressors.
[0010] Such a thermodynamic system ensures return of the major
portion of the oil carried away by the coolant fluid towards the
first compressor. Because of the high pressure prevailing in the
low pressure portion of the first compressor (due to the presence
of the restriction member in the second suction line), the oil
present in the oil pan of the first compressor is driven towards
the oil pan of the second compressor, via the oil level
equalization conduit, so as to balance the oil levels in the first
and second compressors.
[0011] Such a solution, although satisfactory for a thermodynamic
system including two fixed-capacity compressors having close
capacities, is absolutely not satisfactory for a thermodynamic
system including at least one compressor with variable capacity and
more particularly with variable speed, or two fixed-capacity
compressors having very different capacities.
[0012] Indeed, when the compressor with variable speed operates at
a low speed, for example less than or of the order of 30 Hz, for a
certain period and that the second compressor operates, a pressure
unbalance is established between the oil pans of both compressors,
causing a transfer of the majority of the oil from the evaporator
towards the second compressor, and therefore a significant increase
of the oil level in the oil pan of the second compressor and
depletion of oil in the oil pan of the first compressor which may
lead to significant damage of the latter.
[0013] The same applies when the two compressors are with a fixed
capacity and that the second compressor has a capacity much greater
than that of the first compressor.
[0014] Therefore, the solution mentioned earlier does not give the
possibility of obtaining satisfactory balance between the oil
levels regardless of the type of compressors used, and regardless
of the operating conditions of the latter.
[0015] The present invention aims at finding a remedy to these
drawbacks.
[0016] The technical problem at the basis of the invention
therefore consists of providing a compression device which is of a
simple and economical structure, with which balancing of the oil
levels may be obtained in each compressor regardless of the
operating conditions of the compression device, and regardless of
the type of compressors used.
[0017] For this purpose, the present invention relates to a
compression device comprising: [0018] at least one first compressor
and one second compressor mounted in parallel, each compressor
comprising a leakproof enclosure including a low pressure portion
containing an engine and an oil pan on the one hand, and an
admission orifice opening into the low pressure portion on the
other hand, [0019] a suction line intended to be connected to an
outlet of an evaporator, [0020] a first suction conduit arranged
for putting the suction line in communication with the admission
orifice of the first compressor, [0021] a second suction conduit
arranged for putting the suction line in communication with the
admission orifice of the second compressor, and [0022] an oil level
equalization conduit arranged for putting the oil pans of the first
and second compressors in communication,
[0023] wherein the compression device further comprises: [0024] at
least one oil separator mounted on the suction line or on the
second suction conduit, the oil separator comprising an oil outlet
orifice, and [0025] an oil return conduit arranged for connecting
the oil outflow orifice of the oil separator to the oil pan of the
first compressor.
[0026] The presence of an oil separator on the suction line or on
the second suction conduit gives the possibility of ensuring,
regardless of the operating conditions of the compression device,
and regardless of the type of compressors used, a return of the
major portion of the oil driven by the coolant fluid towards the
first compressor via the oil return conduit. The oil present in the
oil pan of the first compressor is then driven towards the oil pan
of the second compressor, via the oil level equalization conduit,
so as to balance the oil levels in the first and second
compressors.
[0027] The compression device according to the invention therefore
ensures balancing of the oil levels in each compressor regardless
of the operating conditions of the compression device, and
regardless of the type of compressors used, the whole only by means
of a low cost oil separator. Further, the compression device
according to the invention ensures the presence of a minimum amount
of oil in the oil pan of the first compressor.
[0028] Advantageously, the oil separator further comprises an inlet
orifice intended to be connected to the outlet of the evaporator so
as to allow an oil-coolant fluid mixture to be introduced into the
oil separator, and a coolant fluid discharge orifice connected to
at least the admission orifice of the second compressor.
[0029] Preferably, the oil separator comprises a separation
chamber, the inlet orifice and the coolant fluid discharge orifice
of the oil separator being respectively in communication with the
separation chamber. The inlet orifice of the oil separator is thus
intended to be connected to the outlet of the evaporator so as to
allow an oil-coolant fluid mixture to be introduced in the
separation chamber.
[0030] According to a first embodiment of the invention, the
suction line comprises a first connection conduit connected to the
inlet orifice of the oil separator and intended to be connected to
the outlet of the evaporator, and a second connection conduit
arranged for putting the coolant fluid discharge orifice of the oil
separator in communication with the first and second suction
conduits. The first and second connection conduits for example have
substantially identical diameters.
[0031] Preferably, the first connection conduit is arranged so as
to extend from the outlet of the evaporator as far as the inlet
orifice of the oil separation device.
[0032] According to an embodiment of the invention, the second
connection conduit extends from the coolant fluid discharge orifice
of the oil separator as far as a diversion point, the first suction
conduit extends from the diversion point as far as the admission
orifice of the first compressor, and the second suction conduit
extends from the diversion point as far as the admission orifice of
the second compressor.
[0033] According to an embodiment of the invention, the second
connecting conduit protrudes inside the separation chamber.
[0034] According to a second embodiment of the invention, the
second suction conduit comprises an upstream conduit portion
arranged for putting the inlet orifice of the oil separator in
communication with the suction line, and a downstream conduit
portion arranged for putting the coolant fluid discharge orifice of
this oil separator in communication with the admission orifice of
the second compressor.
[0035] According to an embodiment of the invention, the downstream
conduit portion protrudes inside the separation chamber.
[0036] Preferably, the suction line is arranged so as to extend
from the outlet of the evaporator as far as a diversion point, the
first suction conduit extends from the diversion point as far as
the admission orifice of the first compressor, the upstream conduit
portion extends from the diversion point as far as the inlet
orifice of the oil separator, and the downstream conduit portion
extends from the coolant fluid discharge orifice of the oil
separator as far as the admission orifice of the second
compressor.
[0037] According to an embodiment of the invention, the oil return
conduit is arranged for opening into the first suction conduit.
According to another embodiment of the invention, the oil return
conduit is arranged for opening into the oil pan of the first
compressor.
[0038] Advantageously, the second suction conduit comprises
restriction means arranged for reducing the flow section of the
coolant fluid in the second suction conduit. The restriction means
are preferentially arranged for maintaining pressure in the low
pressure portion of the first compressor, greater than the pressure
in the low pressure portion of the second compressor when the first
and second compressors are operating simultaneously.
[0039] Advantageously, the restriction means are arranged so that
the flow section of the coolant fluid at the restriction means is
less than the flow section of the coolant fluid at the admission
orifice of the second compressor.
[0040] The restriction means for example include a restriction
member positioned in the second suction conduit.
[0041] According to an embodiment of the invention, the first
compressor is a variable-capacity compressor and the second
compressor is a fixed-capacity compressor.
[0042] Thus, by positioning the oil separator on the suction line
or the second suction conduit and by connecting the oil outlet
orifice of the oil separator to the oil pan of the first
compressor, it is possible to protect the most expensive compressor
of the compression device and most subject to pressure variations
in its oil pan.
[0043] By compressor with variable capacity is meant any compressor
which may have a variable output (or several outputs) with regard
to the suction of the compressor for a same operating point (an
operating point corresponding to a suction pressure, a suction
temperature and a discharge pressure which are given). Among the
known technical solutions for making a compressor with variable
capacity, mention will be made for example of: [0044] a compressor
driven by a variable-speed motor, [0045] a compressor driven by a
motor with two speeds (a two/four pole motor type), [0046] a
compressor driven by a fixed-speed motor plus a gear box, [0047] a
compressor driven by a fixed-speed motor plus an epicycloidal gear
(planetary gear), [0048] a compressor with discharge valves either
opening or closing an internal bypass to the compressor, [0049] a
compressor with multiple compression units, some of which may be
uncoupled, [0050] a compressor with an internal mechanism for
generating intermittent compression.
[0051] According to an alternative embodiment of the invention, the
first and second compressors may be fixed-capacity compressors. The
first and second fixed-capacity compressors may for example have
different capacities.
[0052] Advantageously, the oil separator is a cyclone oil
separator.
[0053] Preferably, the oil level equalization conduit includes at
least one first end portion protruding inside the enclosure of one
of the first and second compressors, the first end portion
including an end wall extending transversely to the longitudinal
direction of said first end portion and an aperture made above said
end wall so that, when the oil level in the oil pan of the
compressor into which the first end portion protrudes, extends
above the upper level of said end wall, oil flows through said
aperture towards the other compressor. Preferably, the first end
portion protrudes inside the enclosure of the second
compressor.
[0054] The oil level equalization conduit advantageously includes a
second end portion protruding inside the enclosure of the other one
of the first and second compressors, the second end portion
including an end wall extending transversely to the longitudinal
direction of said second end portion and an aperture made above the
end wall of said second end portion so that, when the oil level in
the oil pan of the compressor, into which protrudes the second end
portion, extends above the upper level of the end wall of the
second end portion, oil flows through the aperture of the second
end portion towards the other compressor.
[0055] According to an embodiment of the invention, at least one of
the first and second end portions includes an oil return orifice
located below the upper level of the end wall of said end
portion.
[0056] Each of the first and second compressors is for example a
compressor with scrolls.
[0057] Anyhow, the invention will be well understood by means of
the description which follows, with reference to the appended
schematic drawing illustrating as non-limiting examples, two
embodiments of this compression device.
[0058] FIG. 1 is a schematic view of a thermodynamic system
according to a first embodiment of the invention.
[0059] FIG. 2 is a schematic sectional view of a compression device
of the thermodynamic system of FIG. 1.
[0060] FIGS. 3a and 3b are perspective and top views respectively
of an end portion of an oil level equalization conduit of the
compression device of FIG. 2.
[0061] FIG. 4 is a schematic view of a thermodynamic system
according to a second embodiment of the invention.
[0062] FIG. 5 schematically illustrates the main components of a
thermodynamic system 1. The thermodynamic system 1 may be a cooling
system.
[0063] The thermodynamic system 1 comprises a circuit 2 for
circulating a coolant fluid successively including a condenser 3,
an expansion valve 4, an evaporator 5 and a compression device 6
connected in series.
[0064] The compression device 6 comprises a first compressor 7 with
variable capacity, and more particularly with variable speed, and a
second compressor 8 with fixed capacity, and more particularly with
a fixed speed, mounted in parallel. Each compressor 7, 8 is for
example a compressor with scrolls. Each compressor 7, 8 comprises a
body 9 including a low pressure portion 11 containing a motor 12
and an oil pan 13 positioned in the bottom of the body 9, and a
high pressure portion 14, positioned above the low pressure portion
11, containing a compression stage.
[0065] The body 9 of each compressor 7, 8 further includes an
orifice 15 for admitting coolant fluid, opening into an upper
portion of the low pressure portion 11, an equalization orifice 16
opening into the oil pan 13, and a discharge orifice 17 opening
into the high pressure portion 14.
[0066] The compression device 6 also comprises a suction line 19
connected to the evaporator 5, a first suction conduit 21 putting
the suction line 19 in communication with the admission orifice 15
of the first compressor 7, and a second suction conduit 22 putting
the suction line 19 in communication with the admission orifice 15
of the second compressor 8. Each suction conduit 21, 22 comprises a
suction tube 21a, 22a, connected to the suction line 19 and a
connecting sleeve 21b, 22b connected to the corresponding admission
orifice 15, respectively.
[0067] As shown in FIG. 2, the second suction conduit 22 comprises
restriction means arranged for reducing the flow section of the
coolant fluid in said suction conduit. The restriction means are
arranged so that the flow section of the coolant fluid at the
restriction means is less than the flow section of the coolant
fluid at the admission orifice 15 of the second compressor 8. The
restriction means are advantageously positioned in proximity to the
admission orifice 15 of the second compressor 8.
[0068] The restriction means preferably comprise an annular ring 23
attached in the second suction conduit 22, for example by brazing
or crimping. The annular ring 23 includes a longitudinal
through-orifice centered with respect to the wall of the second
suction conduit 22. It should be noted that the outer diameter of
the annular ring 23 substantially corresponds to the inner diameter
of the diversion tube 22a of the second suction conduit 22.
[0069] According to an alternative embodiment not shown in the
figures, the annular ring 23 may be attached in the connecting
sleeve 22b of the second suction conduit 22.
[0070] The compression device 6 further comprises an oil level
equalization conduit 24 connecting the first equalization orifices
16 of the first and second compressors 7, 8 and in fact putting the
oil pans 13 of the first and second compressors in
communication.
[0071] The compression device 6 also comprises a discharge line 26
connected to the condenser 3, a first discharge conduit 27 putting
the discharge line 26 in communication with the discharge orifice
17 of the first compressor 7, and a second discharge conduit 28
putting the discharge line 26 in communication with the discharge
orifice 17 of the second compressor 8.
[0072] The compression device 6 further comprises control means 29
arranged for selectively controlling the respective switching of
the first and second compressors 7, 8 between an operating mode and
a standstill mode, on the one hand, and for modulating the speed of
the motor 12 of the first compressor 7 between a minimum speed and
a maximum speed on the other hand.
[0073] The compression device 6 also comprises an oil separator 31
mounted on the suction line 19. The oil separator 31 includes a
body 32 delimiting a separation chamber 34. The separation chamber
34 includes a cylindrical upper portion extended with a converging
frusto-conical lower portion opposite to the upper portion. The oil
separator 31 thus forms a cyclone oil separator.
[0074] The oil separator 31 also comprises an inlet orifice 35 for
example opening radially or tangentially into the separation
chamber 34, an oil outflow orifice 36 opening into the lower end of
the separation chamber 34, and an orifice for discharging coolant
fluid 37, opening axially into the upper end of the separation
chamber 34.
[0075] The suction line 19 more particularly comprises a first
connecting conduit 19a connected to the outlet of the evaporator 5
on the one hand and to the inlet orifice 35 of the oil separator 31
on the other hand so as to allow an oil-coolant fluid mixture to be
introduced into the separation chamber 34, and a second connecting
conduit 19b connected to the discharge orifice 37 of the oil
separator 31 on the one hand and to the first and second suction
conduits 21, 22 on the other hand. The first and second connecting
conduits 19a, 19b for example have substantially identical
diameters. Advantageously, the second connecting conduit 19b
protrudes inside the separation chamber 34.
[0076] The second connecting conduit 19b preferably extends from
the discharge orifice 37 of the oil separator 31 as far as a
diversion point 38, and the first and second suction conduits 21,
22 respectively extend from the diversion point 38 as far as the
admission orifice 15 of the respective compressor.
[0077] The compression device 6 finally comprises an oil return
conduit 39 arranged for connecting the oil outflow orifice 36 of
the oil separator 31 to the oil pan 13 of the first compressor 7.
The oil return conduit 39 is more particularly arranged for opening
into the first suction conduit 21.
[0078] The operation of the thermodynamic system 1 will now be
described.
[0079] When the first and second compressors 7, 8 are operating,
the oil-coolant fluid mixture from the evaporator 5 penetrates into
the separation chamber 34 of the oil separator 31 via the first
connecting conduit 19a and the inlet orifice 35. Subsequently,
because of the configuration of the separation chamber 34, the
oil-coolant fluid mixture begins to turn along the internal wall of
the separation chamber 34, which causes centrifugation of the
oil-coolant fluid mixture. The result of this is the coalescence of
the oil drops on the internal wall of the separation chamber 34,
and then the fall of the oil by gravity towards the lower end of
the separation chamber 34, i.e. towards the oil outflow orifice 36,
and the flow of coolant fluid through the discharge orifice 37
towards the inlet orifices 15 of the first and second compressors
7, 8. The coolant fluid flow penetrating into the second compressor
8 is then not very loaded with oil.
[0080] The oil separated in the separation chamber 34 then flows in
the oil return conduit 39 towards the oil pan 13 of the first
compressor 7 via the first suction conduit 21. The coolant fluid
flow penetrating into the first compressor 7 is then highly loaded
with oil. Because of the high pressure prevailing in the low
pressure portion 11 of the first compressor 7 (due to the presence
of the restriction member 23 in the second suction conduit 22), the
oil present in the oil pan 13 of the first compressor 7 is driven
towards the oil pan 13 of the second compressor 8, via the oil
level equalization conduit 24, so as to balance the oil levels in
the first and second compressors 7, 8.
[0081] According to an alternative embodiment of the compression
device 6 illustrated in FIGS. 3a and 3b, the oil level equalization
conduit 24 includes at least one first end portion 41 protruding
inside one of the first and second compressors 7, 8.
[0082] The first end portion 41 includes an end wall 42 extending
transversely to the longitudinal direction of the first end portion
41 and an aperture 43 made above the end wall 42 so that, when the
oil level in the oil pan 13 of the compressor into which protrudes
the first end portion 41, extends above the upper level of the end
wall 42, oil flows through the aperture 43 towards the other
compressor. Preferably, each aperture 43 extends over a portion of
the side wall 44 of the corresponding end portion 41.
[0083] The first end portion 41 further includes an oil return
orifice 45 located below the upper level of the end wall 42 of the
first end portion 41. This position of the oil return orifice 45
gives the possibility of avoiding storage of oil beyond a
predetermined level inside the enclosure of the compressor into
which protrudes the first end portion 41.
[0084] According to an alternative embodiment of the compression
device 6, the oil level equalization conduit 24 includes a second
end portion 41 substantially identical with the first end portion,
the first end portion 41 protruding inside one of the first
compressors 7, 8, while the second end portion 41 protrudes inside
the other one of the first and second compressors 7, 8.
[0085] FIGS. 4 and 5 illustrate a thermodynamic system 1 according
to a second embodiment of the invention which differs from the one
illustrated in FIGS. 1 and 2 essentially in that the oil separator
31 is mounted on the second suction conduit 22, in that the second
suction conduit 22 comprises an upstream conduit portion 46a
arranged for putting the inlet orifice 35 of the oil separator 31
in communication with the suction line 19, and a downstream conduit
portion 46b arranged for putting the discharge orifice 37 of the
oil separator 31 in communication with the admission orifice 15 of
the second compressor 8, and in that the oil return conduit 39
directly opens into the oil pan 13 of the first compressor 7.
[0086] According to a second embodiment of the invention, the
suction line 19 extends from the outlet of the evaporator 5 as far
as the diversion point 38, the first suction conduit 21 extends
from the diversion point 38 as far as the admission orifice 15 of
the first compressor 7, the upstream conduit portion 46a extends
from the diversion point 38 as far as the inlet orifice 35 of the
oil separator 31, and the downstream conduit portion 46b extends
from the discharge orifice 37 of the oil separator 31 as far as the
admission orifice 15 of the second compressor 8. Advantageously,
the downstream conduit portion 46b protrudes inside the separation
chamber 34.
[0087] According to this second embodiment of the invention, the
downstream conduit portion 46b comprises restriction means, and
more particularly the annular ring 23.
[0088] According to an alternative embodiment of the second
embodiment of the invention, the second suction conduit 22 may be
without any restriction means in order to limit the manufacturing
costs of the compression device. The oil separator according to
this alternative embodiment is arranged for maintaining pressure in
the low pressure portion of the first compressor, greater than the
pressure in the low pressure portion of the second compressor when
the first and second compressors are operating simultaneously.
[0089] As this is obvious, the invention is not limited to the sole
embodiments of this compression device, described above as an
example, on the contrary, it encompasses all the alternative
embodiments thereof.
* * * * *