Title of Invention

A LIQUID-COOLED ROTOR ASSEMBLY FOR A SUPPERCHARGER

Abstract A rotor assembly for a supercharger assembly is provided. The rotor assembly includes at least one lobe defining at least one cavity. The at least one cavity is configured to contain a fluid operable to cool the at least one lobe. A supercharger incorporating the rotor assembly is also disclosed.
Full Text LIQUID-COOLED ROTOR ASSEMBLY FOR A SUPERCHARGER
TECHNICAL FIELD
[0001] The present invention relates to a liquid-cooled rotor assembly for a
compressor or supercharger assembly.
BACKGROUND OF THE INVENTION
[0002] Roots-type and screw-type positive displacement compressors are
employed in industrial and automotive applications. The compressor or supercharger
may be operatively connected to an internal combustion engine to increase the volume
of intake air communicated to the internal combustion engine thereby increasing the
volumetric efficiency thereof. The supercharger typically includes two interleaved and
counter-rotating rotors each of which may be formed with a plurality of lobes to convey
intake air for subsequent introduction to the internal combustion engine. The efficiency
of the supercharger is dependent on the running clearances between each of the two
rotors and a housing within which the two rotors are rotatably supported.
SUMMARY OF THE INVENTION
[0003] A rotor assembly for a supercharger assembly is provided. The rotor
assembly includes at least one lobe defining at least one cavity. The at least one cavity
is configured to contain a fluid, such as oil or coolant, operable to cool the at least one
lobe.
[0004] In one embodiment, the rotor assembly includes a rotatable shaft member
and the at least one lobe is operatively connected to the shaft member. The shaft
member defines a feed passage operable to communicate the fluid to the at least one
cavity. The shaft member further defines a return passage operable to exhaust the fluid
from the at least one cavity. The feed passage is positioned generally along an axis of
rotation of the shaft member, while the return passage is positioned generally adjacent
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to the outer periphery of the shaft member. A supercharger incorporating the rotor
assembly is also disclosed.
[0005] The above features and advantages and other features and advantages of
the present invention are readily apparent from the following detailed description of the
best modes for carrying out the invention when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Figure 1 is a schematic perspective view of a supercharger assembly
configurned for use with an internal combustion engine;
[0007] Figure 2 is a perspective view of a first and second rotor assembly for use
within the supercharger assembly of Figure 1;
[0008] Figure 3 is a non-planar or revolved cross sectional view, taken along 3-3
of Figure 2, of two adjacent lobes of the first rotor assembly; and
[0009] Figure 4 is a non-planar or revolved cross sectional view, similar to that of
Figure 3, of an alternate embodiment of the first rotor assembly of Figures 1-3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] Referring to the drawings wherein like reference numbers correspond to
like or similar components throughout the several figures, there is shown in Figure 1 a
compressor or supercharger assembly, generally indicated at 10. The supercharger
assembly 10 includes a housing 12. The housing 12 defines an inlet passage 14
configured to induct intake air, represented as arrow 16, into the supercharger assembly
10. The housing 12 further defines an outlet passage 18 configured to exhaust the intake
air 16 from the supercharger assembly 10.
[0011] A rotor cavity 20 is defined by the housing 12 and is configured to contain
a first end second rotor assembly 22 and 24, respectively, rotatably disposed therein. The
first and second rotor assemblies 22 and 24 are interleaved and counter-rotating with
respect to each other. The first rotor assembly 22 includes a plurality of lobes 26
extending radially outward in a clockwise twisting helical shape, as viewed from the

inlet passage 14, while the second rotor assembly 24 includes a plurality of lobes 28
extending radially outward in a counter-clockwise twisting helical shape, as viewed
from the inlet passage 14. The first and second rotor assemblies 22 and 24 cooperate to
convey intake air 16 from the inlet passage 14 to the outlet passage 18. The first and
second rotor assemblies 22 and 24 are rotatably supported within the rotor cavity 20 by
respective first and second shaft member 30 and 32.
[0012] During operation of the supercharger assembly 10, the first and second
rotor assemblies 22 and 24 cooperate to convey intake air 16 from the inlet passage 14
to the outlet passage 18. The temperature of the intake air 16 tends to increase as the
intake air 16 is transferred from the inlet passage 14 to the outlet passage 18, thereby
forming a thermal gradient along the longitudinal axis of the first and second rotors 22
and 24. As a result, the degree of thermal expansion of the first and second rotor
assemblies 22 and 24 will increase during operation of the supercharger assembly 10,
thereby increasing the likelihood of "scuff". Scuff is defined as metal transfer as a
result of the first and second rotor assemblies 22 and 24 contacting one another or the
housing 12. Scuff occurs when the running clearances, i.e. the clearance dimension
between the lobes 26 and 28 and the housing 12 when the supercharger assembly 10 is
operating, reaches zero causing an interference condition and material transfer between
the first and second rotor assemblies 22 and 24 and the housing 12.
[0013] A cooling system 34, such as a loop or a simple tank, is schematically
depicted in Figure 1 and is operable to cool or extract heat energy from the lobes 26
and 28 of the first and second rotor assemblies 22 and 24 during the operation of the
supercharger assembly 10. By cooling the lobes 26 and 28, the thermal expansion of
the first and second rotor assemblies 22 and 24 can be minimized thereby reducing the
likelihood of scuff. Additionally, the cooling system 34 enables tighter running
clearances between the first and second rotor assemblies 22 and 24 and the housing 12
since the dimensional stability of the lobes 26 and 28 during operation of the
supercharger assembly 10 is improved. The cooling system 34 includes a source 35 of
fluid 36, such as oil from a gear case (not shown) of the supercharger assembly 10, or

coolant from a liquid-to-air supercharger intercooler (not shown) or the engine (not
shown), or a completely separate fluid circuit; however, those skilled in the art will
recognize other fluids that may be used within the cooling system 34 while remaining
within the scope of that which is claimed. A pump 38 is in fluid communication with
the source 35 and is operable to communicate the fluid 36 under pressure to feed
passages 40 and 42 defined by respective first and second shaft members 30 and 32 to
effect cooling of the first and second rotor assemblies 22 and 24. Annular grooves 41
and 43 are partially defined by the respective first and second shaft members 30 and 32.
The annular grooves 41 and 43 are operable to return the fluid 36 to the source 35.
[0014] Referring to Figure 2, there is shown a perspective view of the first and
second rotor assemblies 22 and 24 illustrating in greater detail the generally helical
shape of the lobes 26 and 28. Additionally, the feed passages 40 and 42 and the
annular grooves 41 and 43.
[0015] The structure and operation of the first and second rotor assemblies 22
and 24 will be discussed in greater detail with reference to Figure 3. Although only the
first rotor assembly 22 is shown in Figure 3, it should be understood that the same
general structure may be employed with the second rotor assembly 24. Referring to
Figure 3 and with continued reference to Figure 1, there is shown a non-planer cross
sectional view of the first rotor assembly 22. The section is taken along 3-3 of Figure 2
and generally rotates with the helix angle of lobes 26. The first shaft member 30 is
rotatable about an axis of rotation, indicated at A. The feed passage 40 extends
generally along the axis of rotation A and is in communication with a generally radially
extending passage 42 defined by the first shaft member 30. The radially extending
passage 42 is in communication with a cavity 44 defined by the lobe 26. Although only
one radially extending passage 42 is shown in Figure 3, it should be understood that
each of the cavities 44 defined by lobes 26 are in communication with a respective
radially extending passage 42. The lobes 26 and the first shaft member 30 cooperate to
define a generally annular passage 46. The annular passage 46 extends axially along
the first shaft member 30 and is in communication with a return passage 48 defined by

the first shaft member 30. The return passage 48 extends generally axially along the
outer periphery of the first shaft member 30.
[0016] During operation of the supercharger assembly 10 of Figure 1, the
cooling system 34 provides fluid 36, indicated as arrows in Figure 3, to the feed
passage 40. The fluid 36 is forced radially outward, through the radially extending
passage 42, and into the cavity 44. The fluid 36 is at least partially forced radially
outward by the centrifugal forces exerted thereon by the rotation of the first shaft
member 30. Subsequently, the fluid 36 travels the length of the cavities 44 to extract
heat energy and thereby cool the lobes 26 of the first rotor assembly 22. The fluid 36,
having traveled the length of the lobes 26, is exhausted into the generally annular
passage 46 where the fluid is communicated to the return passage 48 for later
communication to the cooling system 34. The annular groove 41 is defined by the first
shaft member 30 and is operable to facilitate the exhausting of fluid 36 from the return
passage 48.
[0017] By cooling the lobes 26 and 28, the running clearances between the lobes
26 and 28 and the housing 12 may be minimized while reducing the likelihood of scuff.
Therefore, the operating efficiency of the supercharger assembly 10 may be increased
by maintaining the temperature of lobes 26 and 28 within predetermined limits. It
should be understood that with certain configurations of the first rotor assembly 22 and
operating speeds of the supercharger assembly 10, the pump 38 may not be necessary
since the feed passage 40 is centrally located along the axis of rotation A of the first
shaft member 30, while the return passage 48 is provided on the outer periphery of the
first shaft member 30. As such, the centrifugal forces exerted on the fluid 36 by the
rotation of the first shaft member 30 may be sufficient to enable the pumping of the
fluid 36 through the first rotor assembly 22 in lieu of the pump 38. The first and
second rotor assemblies 22 and 24 may have helical-type, screw-type, or straight-type
configurations for lobes 26 and 28 while remaining within the scope of that which is
claimed. As stated hereinabove, the lobes 26 and 28 of the first and second rotor
assemblies 22 and 24 have a generally helical shape; as such, the fluid 36 is pumped

through the cavities 44 during rotation of the first and second rotor assemblies 22 and
24.
[0018] Referring to Figure 4, there is shown an alternate embodiment of the
first rotor assembly 22 of Figures 1 through 3, generally indicated at 22A. The first
rotor assembly 22A is similar to the first rotor assembly 22; however the cavity 44 is
formed by cross drilling lobes 26A. Plugs 50, such as cup plugs or ball bearings, are
mounted to the lobes 26A and are operable to prevent leakage of fluid 36 from the
cavity 44 during operation of the first rotor assembly 22A. By cross-drilling the lobes
26A, a conventional, i.e. non liquid-cooled rotor assembly may be adapted to a liquid
cooled rotor assembly. Additionally, cavities 44 may be easier to form within certain
rotor shapes, such as helix shapes, by cross drilling as opposed to investment casting or
other casting methods.
[0019] In operation of the first rotor assembly 22A, the fluid 36 is
communicated to the feed passage 40 and is subsequently communicated to the cavities
44 via the radially extending passages 42. As with the first rotor assembly 22 of Figure
3, the fluid 36 travels the length of the cavities 44 to extract heat energy and thereby
cool the lobes 26A of the first rotor assembly 22A. The fluid 36, having traveled the
length of the lobes 26A, is exhausted into the return passage 48 for later communication
to the cooling system 34 via the annular groove 41.
[0020] Although the discussion has focused on the application of the supercharger
assembly 10 to an internal combustion engine, those skilled in the art will recognize other
applications of the supercharger 10 such as a compressor for industrial application,
compressor for fuel cell applications, etc. While the best modes for carrying out the
invention have been described in detail, those familiar with the art to which this invention
relates will recognize various alternative designs and embodiments for practicing the
invention within the scope of the appended claims.

CLAIMS
1. A rotor assembly for a supercharger assembly comprising:
at least one lobe defining at least one cavity; and
wherein said at least one cavity is configured to contain a fluid
operable to cool said at least one lobe.
2. The rotor assembly of claim 1, further comprising:
a rotatable shaft member;
wherein said at least one lobe is operatively connected to said shaft
member;
5 wherein said shaft member defines a feed passage operable to
communicate said fluid to said at least one cavity; and
wherein said shaft member defines a return passage operable to
exhaust said fluid from said at least one cavity.
3. The rotor assembly of claim 1, wherein said fluid is one of coolant
and oil.
4. The rotor assembly of claim 2, wherein said feed passage is
positioned generally along an axis of rotation of said shaft member.
5. The rotor assembly of claim 2, wherein said return passage is
positioned generally adjacent to the outer periphery of said shaft member.
6. The rotor assembly of claim 2, wherein said at least one lobe and
said shaft member cooperate to define an annular passage operable to communicate said
fluid between said at least one cavity and said return passage.

7. The rotor assembly of claim 1, wherein said at least one cavity is
cross-drilled.
8. A supercharger assembly comprising:
a housing defining a rotor cavity;
first and second rotor assemblies rotatably supported within said
rotor cavity by respective first and second shaft members;
5 wherein said first and second rotor assemblies include respectively
a first and second plurality of lobes;
wherein each of said first and second plurality of lobes define at
least one cavity; and
wherein said at least one cavity is configured to contain a fluid
10 operable to cool said first and second plurality of lobes.
9. The supercharger assembly of claim 8, wherein said first and
second shaft members each define at least one feed passage operable to communicate
said fluid to said at least one cavity and wherein said first and second shaft members
define a return passage operable to exhaust said fluid from said at least one cavity.
10. The supercharger assembly of claim 8, wherein said fluid is one of
coolant and oil.
11. The supercharger assembly of claim 9, wherein said feed passage
is positioned generally along an axis of rotation of each of said first and second shaft
members.
12. The supercharger assembly of claim 9, wherein said return passage
is positioned generally adjacent to the outer periphery of each of said first and second
shaft members.

13. The supercharger assembly of claim 9, wherein said first and
second plurality of lobes and said respective first and second shaft members cooperate to
define annular passages operable to communicate said fluid between said at least one
cavity and said return passage.
14. A rotor assembly for a supercharger assembly comprising:
a rotatable shaft member;
a plurality lobes extending generally radially from said shaft
member, each of said plurality of lobes defining at least one cavity;
5 wherein said at least one cavity is configured to contain a fluid
operable to cool each of said plurality of lobes;
wherein said shaft member defines at least one feed passage
operable to communicate said fluid to said at least one cavity; and
wherein said shaft member defines a return passage operable to
10 exhaust said fluid from said at least one cavity.
15. The rotor assembly of claim 14, wherein said fluid is one of
coolant and oil.
16. The rotor assembly of claim 14, wherein said fluid is
communicated to said feed passage by a pump.

A rotor assembly for a supercharger assembly is provided. The rotor
assembly includes at least one lobe defining at least one cavity. The at least one cavity is
configured to contain a fluid operable to cool the at least one lobe. A supercharger
incorporating the rotor assembly is also disclosed.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=FHeY9MI0AoIYvUEcuOdxxA==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 272893
Indian Patent Application Number 809/KOL/2008
PG Journal Number 19/2016
Publication Date 06-May-2016
Grant Date 29-Apr-2016
Date of Filing 02-May-2008
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 RENAISSANCE CENTER, DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 GREGORY P. PRIOR 551 OAKLAND AVENUE BIRMINGHAM, MICHIGAN 48009
2 ROXANN M. BITTNER 2816 BAMLET ROAD, ROYAL OAK, MICHIGAN 48073
PCT International Classification Number F01D25/00,F01D5/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/768598 2007-06-26 U.S.A.