U.S. patent application number 11/990135 was filed with the patent office on 2010-06-03 for pump casing.
This patent application is currently assigned to ATELIERS BUSCH SA. Invention is credited to Theo Bilger, Olivier Goepfert, Philippe Schwob.
Application Number | 20100135837 11/990135 |
Document ID | / |
Family ID | 36143196 |
Filed Date | 2010-06-03 |
United States Patent
Application |
20100135837 |
Kind Code |
A1 |
Goepfert; Olivier ; et
al. |
June 3, 2010 |
Pump Casing
Abstract
The invention relates to a pump housing (2) comprising a
dual-wall casing (3) which enables a first fluid (4) to flow at
least partially around a compression chamber (5) for compressing a
second fluid (6), said compression being performed with at least
two elongated rotors (7, 8). The dual-wall casing (3) comprises:
(i) a first wall (10) which defines the volume of the compression
chamber (5), and (ii) a second wall (11) which extends around the
first wall (10) at a distance (12) from same such as to enable the
first fluid (4) to flow therethrough. The pump housing (2) consists
of two subassemblies (13, 14), namely a first subassembly (13) and
a second subassembly (14), which are assembled along a sealing
surface (15) that is essentially orthogonal to the longitudinal
axes (70, 80) of the rotors (7, 8). Both the first subassembly (13)
and the second subassembly (14) are characterised in that they
consist of a rigid element (16) which is moulded from a first
thermally-conductive material and which comprise two opposing
faces, namely a first face (18) and a second face (19). According
to the invention, the above-mentioned first wall (10), which is
moulded with the rigid element (16), is disposed beyond the first
face (18) such as to extend essentially orthogonally thereto, while
the second wall (11) is also disposed beyond the first face (18)
such as to extend essentially orthogonally thereto, but in parallel
to a fourth face (21) of the first wall (10) without being joined
to same. In addition, cut-outs (23) are recessed into the first
face (18) such that each cut-out forms at least one housing for a
first member (9) that is used to guide the rotation of one of the
opposing ends (71, 72, 81, 82) of one of the rotors (7, 8).
Inventors: |
Goepfert; Olivier;
(Porrentruy, CH) ; Schwob; Philippe;
(Roppentzwiller, FR) ; Bilger; Theo;
(Helfrantzkirch, FR) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
ATELIERS BUSCH SA
Chevenez
CH
|
Family ID: |
36143196 |
Appl. No.: |
11/990135 |
Filed: |
August 25, 2005 |
PCT Filed: |
August 25, 2005 |
PCT NO: |
PCT/EP2005/054194 |
371 Date: |
February 7, 2008 |
Current U.S.
Class: |
418/83 |
Current CPC
Class: |
F04C 18/086 20130101;
F04C 18/16 20130101; F05C 2251/044 20130101; F04C 2230/21 20130101;
F04C 2230/60 20130101; F04C 2/086 20130101; F04C 2240/30 20130101;
F05C 2251/046 20130101 |
Class at
Publication: |
418/83 |
International
Class: |
F04C 29/04 20060101
F04C029/04 |
Claims
1. Pump casing having a double-walled shell which permits the
circulation of a first fluid, in particular a heat-transfer medium,
at least partially about a chamber of compression of a second
fluid, the compression being accomplished by means of at least two
elongated rotors, which, having longitudinal axes, are situated in
said compression chamber, the rotors being guided in rotation about
their longitudinal axes by the elements, referred to as first
elements for guiding in rotation, positioned at the level of
opposite ends which these rotors comprise, the double-walled shell
having, on the one hand, a first wall which determines the volume
of the compression chamber, and, on the other hand, a second wall
which extends around the first wall with a certain spacing intended
for the circulation of the first fluid, said pump casing being made
up of two subassemblies, referred to as first and second, which are
assembled along a joint face substantially orthogonal to the
longitudinal axes of the rotors, each first subassembly and second
subassembly being characterized in that it comprises a rigid
element which, cast in a first thermally conducting material, has
two opposite faces, being a first face and a second face, with
situated beyond the first face, on the one hand, the first wall
which, cast with this rigid element, extends substantially
orthogonally to said first face and is transversally delimited
between two opposite faces, referred to as third face and fourth
face, the third face delimiting the compression chamber laterally,
the fourth face constituting a surface of exchange with the first
fluid, longitudinally limited by a fifth face which defines at
least one bearing area for joining with the fifth face of a first
subassembly or second subassembly with which it must be joined
along the joint face in a manner so as to constitute a pump casing,
on the other hand, the second wall which extends substantially
orthogonally to said first face and parallel to the fourth face of
the first wall, while being without any connection to said fourth
face, situated set back with respect to the first face, cutouts
which each constitute at least one accommodation for a first
element for guiding in rotation of one of the opposite ends of one
of the rotors.
2. Pump casing according to claim 1, wherein on at least one of
said first and second subassemblies, the first wall is connected to
the rigid element which bears it through a connecting part which
elicits a displacement of said first wall in a first direction
substantially orthogonal to the joint face, and this by elastic
deformation of said connecting part.
3. Pump casing according to claim 1, wherein each cutout situated
set back with respect to the first face, likewise constitutes an
accommodation for a second element intended to ensure the tightness
between each of the opposite ends of an elongated rotor and the
rigid element in which the cutout under consideration is
situated.
4. Pump casing according to claim 1, wherein the first subassembly
and the second subassembly constituting the pump casing are joined
by means of third elements which pull the one toward the other in a
manner so as to apply tightly, one against the other, the fifth
faces of the rigid elements of each first subassembly and second
subassembly.
5. Pump casing according to claim 4, wherein the first subassembly
and the second subassembly constituting the pump casing are joined
by means of third elements consisting of tension rods which: each
extend in a second direction substantially orthogonal to the joint
face and of which at least certain ones pass through the space
situated between the first wall and the second wall of each first
subassembly and second subassembly, find support at the level of
the second face of each rigid element which comprises one of said
first and second subassemblies.
6. Pump casing according to claim 1, wherein: the first subassembly
and the second subassembly constituting the pump casing are joined
by means of third elements which pull said first and second
subassemblies, one toward the other, in a manner so as to apply
tightly, one against the other, the fifth faces of the rigid
elements of each first subassembly and second subassembly, the
second wall of each first subassembly and second subassembly extend
beyond the first face and comprise a face which, referred to as the
sixth face, extends in a second plane parallel to the fifth face of
the same first or second subassembly, but set back with respect to
this fifth face, in a manner such that when the fifth faces of the
first subassembly and of the second subassembly rest one against
the other, the sixth faces of these subassemblies are spaced apart
by a predetermined value "E", such that an interstice remains
between them.
7. Pump casing according to claim 6, wherein: at least one of the
fifth faces of the first subassembly and of the second subassembly
which rest one against the other, bears at least one first gasket
which co-operates with the other fifth face and ensures the
peripheral tightness of the compression chamber at the level of the
two fifth faces placed resting one against the other, at least one
of the sixth faces of the first subassembly and of the second
subassembly which are situated vis-a-vis, rest one against the
other through the agency of at least one second gasket which
ensures the peripheral tightness of the space situated between the
first wall and the second wall, in spite of the interstice of
predetermined value "E" which remains between these sixth
faces.
8. Pump casing according to claim 1,wherein the bearing area for
joining constituted by the fifth faces of two first and second
subassemblies intended to be joined have complementary elements of
transversal positioning, male and female, in such a way as to
enable the relative transversal positioning of the two first and
second subassemblies.
9. Pump casing according to claim 1 and intended to accommodate at
least two elongated rotors, the longitudinal axes of which are
situated in a same plane, wherein the bearing area for joining made
up of the fifth face of each first or second subassembly has two
complementary elements of transversal positioning, male and female,
which are situated in said third plane.
10. Pump casing according to claim 1, wherein the first and the
second subassemblies, which it comprises, are composed such that
the joint face is situated at between a quarter and three quarters
of the distance which separates the first faces opposite said
joined first and second subassemblies.
11. Pump casing according to claim 1, wherein the first and the
second subassemblies which it comprises are composed such that the
joint face is situated substantially in the middle of the distance
which separates the first faces opposite said joined first and
second subassemblies.
12. Pump casing according to claim 1 and having at least one first
channel which permits the injection into the chamber of a third
fluid, referred to as dilution fluid, and this from the exterior of
the chamber, this body being wherein at least this first channel
intended to route the third fluid, introduced through an entry
situated in the rigid element and expelled into the compression
chamber through at least one exit orifice situated at the level of
the third face, is made in the thickness of said first wall.
13. Pump casing according to claim 1, wherein the second wall of
each first and second subassembly is formed by molding from a cast
(duplicate molding).
14. Pump casing according to claim 1, wherein the second wall of
each first and second subassembly is formed by duplicate molding of
a second material identical to the first material constituting the
first wall.
15. Pump casing according to claim 1, wherein the second wall of
each first and second subassembly is formed by duplicate molding of
a second material different from the first material constituting
the first wall.
16. Pump casing according to claim 1 and intended to house two
elongated rotors disposed parallel in the compression chamber, said
compression chamber comprising a first orifice for admission of the
second fluid and a second orifice for outflow of said second fluid
characterized in that the rigid element of each first and second
subassembly comprises a second channel which opens out into the
first face through an aperture which, constituting one of said
first orifice or second orifice, is provided with a plane of
symmetry which is, on the one hand, situated at mid-distance
between the longitudinal axes of the elongated rotors and, on the
other hand, perpendicular to the third plane which contains the
longitudinal axes of said rotors.
17. Pump casing according to claim 16, wherein the second channel
is determined by transverse sections which each have a plane of
symmetry that is, on the one hand, situated at mid-distance between
the longitudinal axes of the elongated rotors and, on the other
hand, perpendicular to the third plane which contains the
longitudinal axes of said rotors.
18. Pump casing according to claim 1, wherein each first and second
subassembly which it comprises possesses a plane of symmetry which
is, on the one hand, situated at mid-distance between the
longitudinal axes of the elongated rotors and, on the other hand,
perpendicular to the third plane which contains the longitudinal
axes of said rotors.
19. Pump casing according to claim 1, wherein the second orifice
for outflow of the second fluid is well formed and disposed in the
subassembly which comprises it in a way so as to permit removal by
gravity of any condensates situated in the lower part of the
compression chamber.
20. Pump comprising a pump casing according to claim 1.
Description
[0001] The invention relates to a pump casing.
[0002] The invention relates more specifically, but not
exclusively, to the field of pumps which, using rotors, are used as
compressors for gaseous fluids.
[0003] The invention obviously relates to the pump which includes
this casing.
[0004] In one of the simplest embodiments, U.S. Pat. No. 2,460,957,
the pump casing is made up of two assemblies, referred to as first
and second, which are joined along a joint face substantially
orthogonal to the longitudinal axes of the rotors.
[0005] In the pump casing, the rotors are guided in rotation along
their longitudinal axes by the guide elements, referred to as first
guide elements, positioned at the level of the opposite ends which
they comprise.
[0006] Generally the casings of such pumps are achieved by casting
the walls in metallic material, and certain surfaces of these walls
are worked by machining, in particular by boring, to define a
chamber, referred to as compression chamber, in which the rotors
are then placed.
[0007] Manufacture of said subassemblies by casting metallic
material is greatly facilitated when the ratio between the
longitudinal dimension and the transverse dimension (thickness) of
each of the walls which define them is close to one.
[0008] Although not obligatory, the construction in two half
subassemblies whose longitudinal dimension corresponds
substantially to half the longitudinal dimension of the pump casing
is preferred because it allows casting of the metallic material to
be facilitated.
[0009] Moreover, the reduced longitudinal dimension of each chamber
part included in a subassembly also makes it possible to ensure an
increased machining precision.
[0010] The situation becomes complicated when the compression
chamber must be cooled through circulation of a heat transfer
medium.
[0011] In fact, the pump casing must have a double-walled shell
which permits the circulation of a heat transfer medium around the
compression chamber.
[0012] In this type of pump, the double-walled shell has, on the
one hand, a first wall that determines the volume of the
compression chamber, and, on the other hand, a second wall which
extends around the first wall with a certain spacing intended for
the circulation of the first fluid.
[0013] With this type of structure, one encounters problems of
tightness when operating the pump, which problems are caused by
differential dilatation of the first and of the second wall.
[0014] One result which the invention aims to obtain is a
double-walled pump casing whose structure enables surmounting the
conventional problems encountered both during manufacture and
during operation of the pump.
[0015] To this end, the invention has as subject matter a pump
casing conforming to claim 1.
[0016] The invention also has as subject matter a pump including
this casing.
[0017] The invention will be better understood from reading the
description which follows given by way of non-limiting example,
with reference to the drawing representing schematically:
[0018] FIG. 1: an exploded view in perspective of a pump casing
according to the invention,
[0019] FIG. 2: a pump including the pump casing of FIG. 1, seen in
section along a plane which passes through the longitudinal axes of
the rotors which it comprises,
[0020] FIG. 3: an end view of one of the subassemblies made up of a
pump casing according to the invention,
[0021] FIG. 4: a view in transverse section of the subassembly
according to FIG. 3, and this along the mid-plane,
[0022] FIG. 5: on an enlarged scale, a local view in section of a
detail of the joining of the two subassemblies of the pump
casing.
[0023] Referring to the drawing, one sees a pump casing 2 having a
double-walled shell 3 which permits the circulation of a first
fluid 4, in particular a heat-transfer medium, at least partially
around a chamber 5 for compression of a is second fluid 6, the
compression being accomplished by means of at least two elongated
rotors 7, 8, which, having longitudinal axes 70, 80, are situated
in said compression chamber 5.
[0024] The first fluid 4 as well as the second fluid 6 are
symbolized by arrows.
[0025] The rotors 7, 8 are guided in rotation about their
longitudinal axes 70, 80 by elements, referred to as first
elements, for guiding in rotation 9, positioned at the level of
opposite ends 71, 72, 81, 82, which these rotors comprise.
[0026] The double-walled shell 3 has, on the one hand, a first wall
10, which determines the volume of the compression chamber 5, and,
on the other hand, a second wall 11, which extends around the first
wall 10 with a certain spacing 12 intended for the circulation of
the first fluid 4.
[0027] The pump casing 2 is made up of two subassemblies 13, 14,
referred to as first 13 and second 14, which are joined along the
joint face 15 substantially orthogonal to the longitudinal axes 70,
80 of the rotors 7, 8.
[0028] As is apparent in FIG. 1, the two fundamental subassemblies
13, 14 of the pump casing 2 and the rotors 7, 8 make possible
formation of a pump 1.
[0029] In a noteworthy way, each first subassembly 13 and second
subassembly 14 comprises a rigid element 16 which, molded in a
first thermally conducting material, has two opposite faces being a
first face 18 and a second face 19, with
[0030] situated beyond the first face 18, [0031] on the one hand,
the first wall 10 which, cast with this rigid element 16, extends
substantially orthogonally to said first face 18, and is [0032]
transversally delimited between two opposite faces, referred to as
third face 20 and fourth face 21, the third face 20 delimiting the
compression chamber 5 laterally, the fourth face 21 constituting a
surface of exchange with the first fluid 4, [0033] longitudinally
limited by a fifth face 22 which defines at least one bearing area
for joining with the fifth face 22 of a first subassembly 13 or
second subassembly 14 with which it must be joined along the joint
face 15 in a manner so as to constitute a pump casing 2, [0034] on
the other hand, the second wall 11 which extends substantially
orthogonally to said first face 18 and parallel to the fourth face
21 of the first wall 10, while being without connection to said
fourth face 21,
[0035] situated set back with respect to the first face 18, cutouts
23 which each constitute at least one accommodation for a first
element for guiding in rotation 9 of one of the opposite ends 71,
72, 81, 82 of one of the rotors 7, 8.
[0036] The adoption of these technical features allows a structure
to be given to the pump casing 2 that simplifies the manufacturing
radically, at whatever level that may be, i.e. in particular when
the manufacturing comprises the steps of casting and machining.
[0037] As will be more apparent later on, the adoption of these
features allows a pump casing 2 to be constructed comprising a
first and a second subassembly 13, 14 which are adapted to comprise
numerous common features, or even be identical.
[0038] In an equally noteworthy way, on at least one of said first
and second subassemblies 13, 14, the first wall 10 is connected to
the rigid element 16 which bears it through a connecting part 24
which elicits a displacement of said first wall 10 in a first
direction 25 substantially orthogonal to the joint face or joint
plane 15, and this by elastic deformation of said connecting part
24.
[0039] In a preferred embodiment, the connecting part 24 is
constituted by a zone of the rigid element 16 which borders the
first wall 10.
[0040] For example, this zone is constituted by a thinned part of
the rigid element 16.
[0041] Advantageously, this thinned zone extends in a first plane
26 substantially parallel to the joint face or joint plane 15.
[0042] The adoption of these features allows any elongation or
shortening of the first wall 10 to be absorbed by elastic
deformation of the connecting part 24.
[0043] Each cutout 23, situated set back with respect to the first
face 18, likewise constitutes an accommodation for a second element
27 intended to ensure the tightness between each of the opposite
ends 71, 72, 81, 82 of an elongated rotor 7, 8 and the rigid
element 16 in which the cutout 23 under consideration is
situated.
[0044] The second element 27 ensures a tightness called "dynamic",
i.e. a tightness effective during the rotation of the rotors.
[0045] As is apparent in the drawing, each cutout 23 consists of a
bore which comprises a first bearing area 231 for a first element
for guiding in rotation 9 of an end 71, 72, 81, 82 of rotor 7, 8
and a second bearing area 232 for a second element 27 intended to
ensure the tightness between an end 71, 72, 81, 82 of the rotor 7,
8 and the rigid element 16 at the level of which this end is
situated.
[0046] Although this has not been represented, each rotor 7, 8 is
driven in rotation, and the rotations of the different rotors 7, 8
are synchronized.
[0047] As is apparent in FIG. 2, one of the constituent
subassemblies 13, 14 of the pump casing 2 is connected to a housing
17 and to a cover 28.
[0048] Although this has not been represented, it is considered
that it is the housing 17 or the cover 28 which shelters a
mechanism for drive in synchronized rotation of the different
rotors 7, 8 housed in the pump casing 2.
[0049] To permit drive of said rotors 7, 8, at least one of said
first subassembly 13 and second subassembly 14 is provided with
bores which pass right through the rigid element which they
comprise, and the rotors have their ends which traverse said bores
in a manner so as to extend beyond the second face of the rigid
element under consideration.
[0050] The means for driving the rotors 7, 8 in synchronized
rotation can be connected to the ends which pass through said bores
in such a way as to extend beyond the second face of the rigid
element under consideration.
[0051] Preferably, the first subassembly 13 and the second
subassembly 14 are provided with bores which pass right through the
rigid element 16 which they comprise, and the second face 19 of the
rigid element 16 of said first and second subassemblies 13, 14
bears at least one cover 28 which closes off said bores
tightly.
[0052] The first subassembly 13 and the second subassembly 14
constituting the pump casing 2 are joined by means of third
elements 29 which pull the one toward the other in a manner so as
to apply tightly, one against the other, the fifth faces 22 of the
rigid elements 16 of each first subassembly 13 and second
subassembly 14.
[0053] The adoption of these technical features ensures the
cohesion of assembly of the first subassembly 13 and of the second
subassembly 14.
[0054] In a preferred embodiment, the first subassembly 13 and the
second subassembly 14 constituting the pump casing 2 are joined by
means of third is elements 29 consisting of tension rods which:
[0055] each extend in a second direction 30 substantially
orthogonal to the joint face 15 and of which at least certain ones
pass through the space situated between the first wall 10 and the
second wall 11 of each first subassembly 13 and second subassembly
14,
[0056] find support at the level of the second face 19 of each
rigid element 16 which comprises one of said first and second
subassemblies 13, 14.
[0057] The phrase "at the level of the second face 19" must not be
interpreted to mean that the third elements 29 necessarily find
support exactly in the plane of the second face 19.
[0058] For example, the third elements 29 find support on bearing
areas (not shown) which, reserved in the rigid element 16, are
situated set back with respect to said second face 19.
[0059] The adoption of these technical features likewise ensures
the cohesion of the joining of the first subassembly 13 with the
second subassembly 14 by making it possible to apply the joining
stresses in the solid zones of said subassemblies, and this in
second directions 30 which are tangent to the first wall 10.
[0060] In a noteworthy way:
[0061] the first subassembly 13 and the second subassembly 14
constituting the pump casing 2 are joined by means of third
elements 29 which pull said first and second subassemblies 13, 14
one toward the other in a manner so as to apply tightly, one
against the other, the fifth faces 22 of the rigid elements 16 of
each first subassembly 13 and second subassembly 14,
[0062] the second wall 11 of each first subassembly 13 and second
subassembly 14 extend beyond of the first face 18, and comprise a
face which, referred to as the sixth face 31, extends in a second
plane 32 parallel to the fifth face 22 of the same first or second
subassembly 13, 14, but set back with respect to this fifth face
22, in a manner such that when the fifth faces 22 of the first
subassembly 13 and of the second subassembly 14 rest one against
the other, the sixth faces 31 of these subassemblies 13, 14 are
spaced apart by a predetermined value "E", such that an interstice
33 remains between them.
[0063] The adoption of these technical features ensures a perfect
isostatism of the assembly.
[0064] Preferably, the sixth faces are spaced apart by a value "E"
ranging between some hundredths of a millimeter and some tenths of
a millimeter.
[0065] Within the limit of the value of the spacing apart of the
sixth faces 31 (thermal dilatation), the prolongation of the second
walls 11 which bear them cannot affect the fitting together of the
fifth faces 22.
[0066] In a way also notable:
[0067] at least one of the fifth faces 22 of the first subassembly
13 and of the second subassembly 14, which rest one against the
other, bears at least one first gasket 35 which co-operates with
the other fifth face 22 and ensures the peripheral tightness of the
compression chamber 5 at the level of the two fifth faces 22 placed
resting one against the other,
[0068] at least one of the sixth faces 31 of the first subassembly
13 and of the second subassembly 14 which are situated vis-a-vis,
rest one against the other through the agency of at least one
second gasket 36 which ensures the peripheral tightness of the
space situated between the first wall 10 and the second wall 11, in
spite of the interstice 33 of predetermined value "E" which remains
between these sixth faces 31.
[0069] For example, at least one of the fifth faces 22 of the first
subassembly 13 and of the second subassembly 14 comprises a groove
34 receiving a first gasket 35 qui co-operates with the other fifth
face 22.
[0070] Other technical solutions enabling accommodation of the
first gasket exist, and are not described because they belong to
the state of the art.
[0071] The phrase "at least a first gasket 35" and the phrase "at
least a second gasket 36" mean that made use of is at least one
tightness element and/or that the action of each tightness element
can be supplemented or reinforced by use of a tightness material
joined by coating.
[0072] The first gasket 35 and the second gasket 36 ensure a static
tightness, i.e. a tightness between fifth faces which are immobile
one with respect to the other, or sixth faces which are immobile
one with respect to the other.
[0073] In the drawing, the first gasket and the second gasket have
the appearance of a gasket of toric type, but it is a question of
possible solutions for achieving each of said gaskets.
[0074] The first gasket 35 and the second gasket 36 can also
consist of flat gaskets, or can be formed by means of a strand of
material deposited on the faces to be joined.
[0075] The adoption of these technical features ensures perfect
tightness of the compression chamber 5 and of the space in which
the first fluid circulates 4.
[0076] The bearing areas for joining are made up of the fifth face
22 of two first and second subassemblies intended to be joined
having complementary elements of transversal positioning, male 37,
female 38, so as to enable the relative transversal positioning of
the two first and second subassemblies.
[0077] In an advantageous embodiment, the fifth faces 22 are flat,
and the complementary positioning elements comprise pins 37 engaged
in bores 38 made in each bearing area for joining, constituted by a
fifth face 22.
[0078] The adoption of these technical features ensures a strict
positioning of the first and of the second subassembly 13, 14, one
with respect to the other.
[0079] When the pump casing 2 is intended to receive at least two
elongated rotors 7, 8 whose longitudinal axes 70, 80 are situated
in a same third plane, the bearing area for joining, made up of the
fifth face 22 of each first or second subassembly 13, 14, has two
complementary elements of transversal positioning, male 37 and
female 38, which are situated in said third plane 39.
[0080] In this way, the positioning of the two subassemblies 13, 14
of the pump casing 2 is not affected by micro shifts caused by the
succession of cycles of heating and cooling undergone by the
pump.
[0081] Generally, the first and the second subassemblies 13, 14
which it comprises are composed in such a way that the joint face
15 is situated at between one quarter and three quarters of the
distance which separates the first faces 18 opposite said assembled
first and second subassemblies 13, 14.
[0082] Preferably, the first and the second subassemblies 13, 14
which it comprises are composed such that the joint face 15 is
situated substantially in the middle of the distance which
separates the first faces 18 opposite said assembled first and
second subassemblies 13, 14.
[0083] The adoption of these last technical features permits, for
example, forming the pump casing 2 by means of a first and of a
second subassembly 13, 14 which are identical.
[0084] In any case, the adoption of these last technical features
simplifies the machining of the compression chamber 5, but also the
machining of the bores which constitute, on the one hand, the first
bearing areas 231 intended to receive the first elements for
guiding in rotation 9 the ends 71, 72, 81, 82 of elongated rotors
7, 8 and, on the other hand, the second bearing areas 232 intended
to receive the second elements 27 ensuring the tightness between
the ends 71, 72, 81, 82 of the rotors and the rigid element 16.
[0085] When the pump casing 2 has at least one first channel 40
which permits the injection into the chamber of a third fluid 41,
referred to as dilution fluid, and this from the exterior of the
compression chamber, at least this first channel 40 intended to
route the third fluid 41, introduced through an entry situated in
the rigid element 16 and expelled into the compression chamber 5
through at least one exit orifice 42 situated at the level of the
third face 20, is made in the thickness of said first wall 10.
[0086] The third fluid 41 is symbolized by arrows which emanate
from the exit orifices 42.
[0087] The adoption of these technical features permits the routing
of the third fluid 41 to any appropriate place in the compression
chamber 5.
[0088] In a first embodiment, the second wall 11 of each first and
second subassembly 13, 14 is formed by duplicate molding.
[0089] According to a second embodiment, the second wall 11 of each
first and second subassembly 13, 14 is formed by duplicate molding
of a second material identical to the first material constituting
the first wall 10.
[0090] According to a third embodiment, the second wall 11 of each
first and second subassembly 13, 14 is formed by duplicate molding
of a second material different from the first material constituting
the first wall 10.
[0091] The adoption of these technical features makes it possible
to simplify considerably the manufacture of the pump casing 2.
[0092] When the pump casing 2 houses two elongated rotors 7, 8
disposed parallel in the compression chamber 5 comprising a first
orifice for admission 44 of the second fluid 6 and a second orifice
for outflow 45 of said second fluid 6, the rigid element 16 of each
first and second subassembly 13, 14 comprises a second channel 46
which opens out into the first face 18 through an aperture which,
constituting one of said first orifice 44 or second orifice 45, is
provided with a plane of symmetry 47 which is, on the one hand,
situated at mid-distance between the longitudinal axes 70, 80 of
the elongated rotors 7, 8 and, on the other hand, perpendicular to
the third plane 39 which contains the longitudinal axes 70, 80 of
said rotors 7, 8.
[0093] The second channel 46 is determined by transverse sections
which each have a plane of symmetry 47 which is, on the one hand,
situated at mid-distance between the longitudinal axes 70, 80 of
the elongated rotors 7, 8, and, on the other hand, perpendicular to
the third plane 39 which contains the longitudinal axes 70, 80 of
said rotors 7, 8.
[0094] The adoption of these technical features ensures a
symmetrical temperature distribution in each first and second
subassembly, in particular an identical temperature distribution at
the level of first elements for guiding in rotation which are
accommodated in each first and second subassembly.
[0095] In effect, the hot fluid evacuated from the compression
chamber 5 carries the same quantity of heat on both sides of the
plane of symmetry 47.
[0096] Each first and second subassembly 13, 14 which it comprises
possesses a plane of symmetry 47 which is, on the one hand,
situated at mid-distance between the longitudinal axes 70, 80 of
the elongated rotors 7 8, and, on the other hand, is perpendicular
to the third plane 39 which contains the longitudinal axes 70, 80
of said rotors 7, 8.
[0097] The adoption of these technical features reinforces the
uniformity of the temperature distribution.
[0098] In an advantageous way, at least the second orifice for exit
45 of said second fluid 6 is well shaped and disposed in the
subassembly which to comprises it in such a way as to allow the
removal by gravity of any condensates (not shown) situated in the
lower part of the compression chamber 5.
* * * * *