INTEGRATED CLUTCH SUPERCHARGER
TECHNICAL FIELD
[0001] The present invention generally relates to a clutch assembly for use with a
supercharger (e.g., any type of positive displacement fluid pump, including Roots-type rotary
blowers, screw-type air pumps, and any other similar devices).
BACKGROUND
[0002] The use of a supercharger to increase or "boost" the air pressure in the intake
manifold of an internal combustion engine to result in an engine having a greater horsepower
output capability is generally known. The engine may thus have an increased horsepower output
capability than would otherwise occur if the engine were normally aspirated (e.g., the piston
would draw air into the cylinder during the intake stroke of the piston). A conventional
supercharger is generally mechanically driven by the engine, and therefore, may represent a
drain on engine horsepower whenever engine "boost" may not be required and/or desired. Some
sort of engageable/disengageable clutch may be disposed in series between the supercharger
input (e.g., a belt driven pulley) and the rotors of the supercharger.
[0003] There are three basic types of clutch assembly configurations and/or designs: (1) a
large pulley configuration; (2) a small pulley configuration; and (3) a remote mount clutch
configuration. While each of these three basic types of clutch assemblies can operate in a
commercially acceptable and satisfactory manner, there may be potential disadvantages
associated with each type of the above-referenced clutch assemblies. With respect to a large
pulley configuration, for example, the pulley is generally integrated to the rotor, and the pulley is
of a large enough diameter so as to fit over a clutch coil that is mounted to the supercharger
cover. Because the pulley is integrated to the rotor, the pulley design is dependent on the torque
capacity of the clutch. In other words, the pulley diameter must be increased if the torque
capacity of the clutch is increased. , This results in undesirable packaging requirements because
the required pulley diameters are typically too large to be commercially feasible. In addition, a
large pulley has high inertia. With respect to a small pulley configuration, the pulley design may
not be dependent on the size of the clutch coil. However, the pulley is generally integrated with
the clutch armature. Because the clutch armature is fixed to the pulley, the clutch armature is
generally rotating at the speed of the pulley even when the clutch is disengaged, and the armature
may not be particularly stable at higher speeds. In addition, in some configurations, the bearings
may have an increased bearing load, and the absence of relative motion between the inner and
outer race of the bearing when the clutch is in an engaged position may put additional stress
and/or load on the bearings. This may allow damage (e.g., fretting) to the bearings. The fretting
becomes an issue due to the belt loads that must be supported by the stationary bearing. Finally,
with respect to a remote-mount pulley configuration, the pulley has the highest inertia associated
with putting the clutch in an engaged position.
SUMMARY
[0004] It may be desirable to provide an improved clutch assembly configured for use with
a supercharger that may overcome the above-described disadvantages. For example, the
improved clutch assembly may be configured to allow the design of the pulley to be independent
of the torque capacity of the clutch by separating the pulley from the clutch rotor and the clutch
coil, for example. The pulley may also be separated from the clutch armature so that rotation of
the clutch armature is not tied to rotation of the pulley even when the clutch assembly is
disengaged from the supercharger. The design of the improved clutch assembly may also allow
the relatively large size (e.g., diameter) of the clutch assembly to be closer to the main housing of
the supercharger, thereby decreasing the packaging envelope in the area around the pulley.
Finally, in some embodiments, the improved clutch assembly may be configured to allow the
supercharger to achieve required speeds without damage to the clutch components; may enable a
small pulley diameter while maintaining improved bearing life.
[0005] A clutch assembly configured for use with a supercharger includes a first shaft
having a longitudinal axis; a pulley connected to the first shaft; a clutch rotor connected to the
first shaft; a clutch armature unconnected to the first shaft; and a clutch coil spaced along the
longitudinal axis from the pulley. The clutch rotor rotates around the longitudinal axis. The
clutch armature also rotates around the longitudinal axis. The diameter of the pulley is
independent of the diameters of the clutch rotor, the clutch armature, and the clutch coil.
[0006] A supercharger including the clutch assembly is also provided. The supercharger
includes a clutch assembly comprising a clutch housing; a first shaft having a longitudinal axis; a
pulley connected to the first shaft; a clutch rotor connected to the first shaft; a clutch armature
unconnected to the first shaft; and a clutch coil spaced along the longitudinal axis from the
pulley. The clutch rotor rotates around the longitudinal axis. The clutch armature also rotates
around the longitudinal axis. The diameter of the pulley is independent of the diameters of the
clutch rotor, the clutch armature, and the clutch coil. The supercharger further includes a
supercharger housing, a plurality of supercharger rotors disposed within the supercharger
housing, a second shaft configured to drive rotation of the plurality of supercharger rotors; and a
step-up gear connected to the second shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Embodiments of the invention will now be described, by way of example, with
reference to the accompanying drawings, wherein:
[0008] FIG. 1 is a cross-sectional view of a clutch assembly in accordance with an
embodiment of the invention.
[0009] FIG. 2 is a cross-sectional view of a clutch assembly in accordance with an
embodiment of the invention.
[00010] FIG. 3 is a perspective view of a clutch assembly in accordance with an
embodiment of the invention.
[0001 1] FIG. 4 is an exploded perspective view of a clutch armature, clutch rotor, and
clutch coil of a clutch assembly in accordance with an embodiment of the invention.
[0001 2] FIG. 5 is an exploded perspective view of a portion of a clutch assembly in
accordance with an embodiment of the invention.
DETAILED DESCRIPTION
[00013] Reference will now be made in detail to embodiments of the present invention,
examples of which are described herein and illustrated in the accompanying drawings. While the
invention will be described in conjunction with embodiments, it will be understood that they are
not intended to limit the invention to these embodiments. On the contrary, the invention is
intended to cover alternatives, modifications and equivalents, which may be included within the
spirit and scope of the invention as embodied by the appended claims. For example, the present
invention may be used advantageously with superchargers having various designs and
configurations, such as Roots type blower superchargers, screw compressors, and any number of
other various positive displacement pumps.
[00014] A clutch assembly 10 in accordance with an embodiment of the invention is shown
in FIG. 1. The clutch assembly 10 is configured for use with a supercharger 1 in accordance
with an embodiment of the invention. The supercharger 2 may be part of an intake manifold
assembly for an engine (not shown). The engine may include a plurality of cylinders and a
reciprocating piston disposed within each cylinder, thereby defining an expandable combustion
chamber. The engine may include intake and exhaust manifold assemblies for directing
combustion fluid to and from the combustion chamber by way of intake and exhaust valves,
respectively.
[0001 5] The supercharger 12 of the intake manifold assembly may be any positive
displacement pump, including the Roots type blower supercharger as illustrated and described in
U.S. Pat. Nos. 5,078,583 and 5,893,355 which are owned by the assignee of the present
invention and which are hereby incorporated by reference in their entirety, but are not
necessarily limited thereto. The supercharger 12 may also comprise a screw compressors or any
other type of positive displacement pump. In accordance with an embodiment of the invention,
the supercharger 12 may include a plurality (e.g., pair) of rotors 14, each having a plurality of
meshed lobes. The rotors may be disposed in a plurality of parallel, transversely overlapping
cylindrical chambers and may be driven by engine crankshaft torque transmitted thereto in a
known manner (e.g., a drive belt). The supercharger 12 may include a main housing 16 that may
define the plurality of cylindrical chambers. The mechanical drive of the supercharger 12,
including shaft 18, may rotate the rotors 14 at a fixed ratio, relative to the crankshaft speed, such
that the displacement of the supercharger 12 is greater than the engine displacement, thereby
boosting or supercharging the air flowing into the combustion chamber of the engine. The
supercharger 12 may include an inlet port configured to receive fluid from an inlet duct or
passage and an outlet port configured to direct the charged air to the intake valves via a discharge
duct. The inlet duct or passage and the discharge duct may be interconnected by means of a
bypass passage. A bypass valve may be disposed within the bypass passage and may be
configured to be moved between an open position and a closed position by means of an actuator
assembly.
[00016] The supercharger 12 may be coupled to clutch assembly 0 in any manner
conventional in the art. further include an input housing that serves as the clutch housing 12 for
the clutch assembly 10. Clutch assembly 10 includes clutch housing 20, a shaft 22, a pulley 24, a
clutch rotor 26, a clutch armature 28, and a clutch coil 30. The clutch housing 20 may be
configured to house other components of the clutch assembly 10. Clutch housing 12 may be
smaller in diameter at a first end 32 and larger in diameter at a second end 34. The first end 32
may be proximate pulley 24. The second end 34 may be proximate the main housing 16 of the
supercharger 12.
[0001 7] Shaft 22 may have a longitudinal axis 36 about which shaft 22 may rotate. Shaft 22
may be supported within clutch housing 20 by at least one bearing 38. For example and without
limitation, shaft 22 may be supported within clutch housing 12 by a plurality (e.g., pair) of
bearings 38, 40. The bearings 38, 40 may be disposed between the clutch housing 20 and shaft
22. Referring now to FIGS. 2-3, an alternative embodiment of the clutch assembly 110 is
generally illustrated. As generally illustrated in FIGS. 2-3, at least a portion of the pulley 24 may
circumferentially surround at least one bearing 38. By locating pulley 24 directly over at least
one bearing 38, the other bearing 40 may not need to be configured to support a radial load
exerted by the pulley 22. Each of the bearings 38, 40 may comprise an inner race and an outer
race in accordance with an embodiment of the invention. There may be substantially no relative
motion between the inner race and the outer race of the bearings 38, 40 when the clutch assembly
10, 110 is engaged.
[00018] Referring now to FIGS. 1-3 and 5, 6, the pulley 24 may be configured to transmit
torque from the engine crankshaft (not shown) to shaft 22 during engagement of the clutch
assembly 10. The pulley 24 may be connected to shaft 22. The pulley 24 may be disposed
externally to shaft 22 in accordance with an embodiment of the invention. The pulley 24 may be
disposed at an end of shaft 22 and may circumferentially surround shaft 22. The pulley 24 may
be external to the clutch housing 20 in accordance with an embodiment of the invention. The
pulley 24 may be axially spaced along the longitudinal axis 36 from the clutch housing 20. In
accordance with an embodiment of the invention, at least one bearing 38 that is disposed
between the clutch housing 20 and shaft 22 may be proximate the pulley 22. Another bearing 40
may be disposed between the clutch housing 20 and shaft 22 closer toward the main housing 16
of the supercharger 12. The pulley 24 may be separated from (i.e., not integral with) other
components of the clutch assembly 10. For example, the pulley 24 may be separated from (i.e.,
not integral with) the clutch armature 28.
[0001 9] The pulley 24 may have a diameter that is independent of the diameters of the
clutch rotor 26, the clutch armature 28, and the clutch coil 30. The pulley 24, including its
design and configuration, is independent of the torque capacity of the clutch rotor 26, the clutch
armature 28, and the clutch coil 30. In accordance with a certain torque capacity of the
supercharger 12, the pulley 24 may have a diameter that is less than about 85 mm in accordance
with an embodiment of the invention. The pulley 24 may have a diameter that is between about
45 mm and about 85 mm in accordance with an embodiment of the invention. Based on the
diameter of the pulley 24, the pulley 24 may conventionally be considered a small pulley. The
pulley 24 may have a diameter that is smaller than the diameter of the clutch coil 30 in
accordance with an embodiment of the invention, as the pulley 24 may not surround the clutch
coil 30 in accordance with an embodiment of the invention. The pulley 24 may also not be
integrated with clutch rotor 26 in accordance with an embodiment of the invention.
[00020] The clutch rotor 26 may be configured to be magnetized and set up a magnetic loop
that attracts the clutch armature 28. The clutch rotor 26 may be connected to shaft 22 and/or
pulley 24 in accordance with an embodiment of the invention. The clutch rotor 26 may rotate
around the longitudinal axis 36 of shaft 22. The clutch rotor 26 is not connected to shaft 18 of
the supercharger as may be conventional in small pulley designs. The clutch rotor 26 may
comprise steel in accordance with an embodiment of the invention. Although steel is mentioned
in detail for one embodiment of the invention, the clutch rotor 26 may comprise any number of
other materials in accordance with other embodiments of the invention. The clutch rotor 26 may
rotate at rotational speeds that are at least the same as the pulley 24 and may rotate at rotational
speeds greater than those capable by the clutch armature 28 in an embodiment of the invention.
Because the clutch rotor 26 may be connected to shaft 22 and/or pulley 24, the clutch rotor 26
may always maintain the same rotational speed as the pulley 24 in accordance with an
embodiment of the invention. In other words, the clutch rotor 26 may rotate at a rotational speed
that is substantially the same as the rotational speed of shaft 22 even when the clutch assembly
10 is disengaged. The clutch rotor 26 may generally be more stable at higher speeds than the
clutch armature 28. The clutch rotor 26 may be disposed between the clutch armature 28 and the
clutch coil 30 along the longitudinal axis 36 of shaft 22. The clutch rotor 26 may have a first
face 42 that is configured to at least partially surround the clutch coil 30. The clutch rotor 26
may have a second face 44 (i.e., opposing the first face 42) that is configured to face the clutch
armature 28.
[00021] The clutch armature 28 may rotate around the longitudinal axis 36 of shaft 22. The
clutch armature 28 may be configured to be pulled against the clutch rotor 26 and apply a
frictional force at contact. The load of the clutch armature 28 may thus be accelerated to match
the rotational speed of the clutch rotor 26. The clutch armature 28 may be disposed between the
clutch rotor 18 and the supercharger 12 along the longitudinal axis 36 of shaft 22. The clutch
armature 28 may have a first face 46 that is configured to face the second face 44 of the clutch
rotor 26 and may include a friction material. The clutch armature 28 may have a second face 46
(i.e., opposing the first face 44) that is configured to face the supercharger 12. The clutch
armature 28 may be connected to shaft 18 of supercharger 12 through a spline and bolt. The
clutch armature 28 may contain speed sensitive components (e.g., friction materials and springs)
in accordance with an embodiment of the invention. The rotational speed of the clutch armature
28 may be less than the rotational speed of shaft 22 when the clutch assembly 10, 110 is
disengaged. Accordingly, the clutch armature 28 may be configured to coast down to a stop in
accordance with an embodiment of the invention when the clutch assembly 10, 110 is
disengaged, rather than always having to maintain the same rotational speed as the pulley 24.
Clutch armature 28 may not be connected to shaft 22 and/or pulley 24 in an embodiment of the
invention. Instead, clutch armature 28 may be separated from the pulley 24 in accordance with
an embodiment of the invention. Clutch armature 20 may be connected to shaft 18 of the
supercharger 12. The rotational speed of the clutch armature 28 may be substantially the same as
the rotational speed of shaft 22 when the clutch assembly 10, 110 is engaged. Because it may be
more difficult to keep the clutch armature 28 stable at higher speeds because of the inclusion of
speed sensitive material, like the friction material, the clutch armature 28 may not be connected
to shaft 22 and/or pulley 24. The clutch armature 28 may be separated from the pulley 24, and
therefore, the clutch armature 28 may not influence the size and/or range of the pulley 24. By
separating the clutch armature 28 from the pulley 24, the size of the clutch housing 20 in the area
around the pulley 24 may be decreased. Furthermore, the size and configuration of the pulley 24
may not depend on the size and/or torque capacity of the armature 28.
[00022] The clutch coil 30 may comprise a source of magnetic flux. An electrical current
and/or voltage may be applied to the clutch coil 30 to generate a magnetic field in the vicinity of
the clutch coil 30 and produce magnetic lines of flux. The intensity of the magnetic field may be
proportional to the level of current provided. This flux may then be transferred through the small
working air gap between the clutch coil 30 and the clutch rotor 26. The clutch rotor 26 may thus
become magnetized and set up a magnetic loop that attracts the clutch armature 28. The clutch
armature 28 may then be pulled against the clutch rotor 26 and a frictional force may be applied
at contact and the load on the clutch armature 28 may be accelerated to match the speed of the
clutch rotor 26. When current and/or voltage is removed from the clutch assembly 10, 110, the
clutch armature 28 may be free to turn with the shaft 18 of supercharger 12. The clutch coil 30
may not be surrounded by pulley 24. Instead, the clutch coil 30 may be mounted in the clutch
rotor 26 and may be located closer to the housing 16 of the supercharger 12. The clutch coil 30
may be disposed between the clutch rotor 26 and the clutch housing 20 in a direction along the
longitudinal axis 36 of shaft 22. The clutch coil 30 may be spaced along the longitudinal axis 36
of shaft 22 from the pulley 24. The clutch coil 30 may be separated from the pulley 24, and
therefore, the clutch coil 30 may not influence the size and/or range of the pulley 24. By
separating the clutch coil 30 from the pulley 24, the size of the clutch housing 20 in the area
around the pulley 24 may be decreased. Furthermore, the size and configuration of the pulley 24
may not depend on the size and/or torque capacity of the clutch coil 30.
[00023] The clutch coil 30 may be controlled by an electronic control unit (ECU) (not
shown) that provides an electrical signal to the clutch coil 30 (e.g., via wires 52). The ECU may
process input, such as for example, but not limited to, sensor readings corresponding to vehicle
parameters and process the input according to log rules to determine the appropriate electrical
signal to provide to clutch coil 30. The ECU may comprise a microprocessor having sufficient
memory to store the logic rules (e.g., in the form of a computer program) for controlling
operation of the clutch assembly 10, 110.
[00024] A supercharger 12 including a clutch assembly 10, 110 in accordance with an
embodiment of the invention may further include a step-up gear 50 connected to shaft 18 of the
supercharger 12. Accordingly, at least one of the rotors 14 of the supercharger 12 may utilize an
input drive configuration including for example and without limitation, shaft 8 and step up gear
50, by means of which the supercharger 12 may receive input drive torque. A supercharger 12 in
accordance with an embodiment of the invention may comprise the clutch assembly 10, 110;
housing 16; a plurality of rotors 14 disposed within housing 16; shaft 18 configured to drive
rotation of the plurality of rotors 14; and step-up gear 50 connected to shaft 18.
[00025] The foregoing descriptions of specific embodiments of the present invention have
been presented for purposes of illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise forms disclosed, and various modifications and
variations are possible in light of the above teaching. The embodiments were chosen and
described in order to explain the principles of the invention and its practical application, to
thereby enable others skilled in the art to utilize the invention and various embodiments with
various modifications as are suited to the particular use contemplated. The invention has been
described in great detail in the foregoing specification, and it is believed that various alterations
and modifications of the invention will become apparent to those skilled in the art from a reading
and understanding of the specification. It is intended that all such alterations and modifications
are included in the invention, insofar as they come within the scope of the appended claims. It is
intended that the scope of the invention be defined by the claims appended hereto and their
equivalents
CLAIMS
What is claimed:
1. A clutch assembly (10) configured for use with a supercharger (12), the clutch
assembly (10) comprising:
a first shaft (18) having a longitudinal axis (36);
a pulley (24) connected to the first shaft (36);
a clutch rotor (14) connected to the first shaft ( 8), wherein the clutch rotor (14)
rotates around the longitudinal axis (36);
a clutch armature (28) unconnected to the input shaft (18), wherein the clutch
armature (28) rotates around the longitudinal axis (36); and
a clutch coil (30) spaced along the longitudinal axis (36) from the pulley (24),
wherein the diameter of the pulley (24) is independent of the diameters of the clutch rotor (26),
the clutch armature (28), and the clutch coil (30).
2. The clutch assembly (10) of claim 1, wherein the clutch armature (28) is
connected to a second shaft (22), the second shaft (22) comprising part of the supercharger (12).
3. The clutch assembly (10) of claim 1, wherein the clutch armature (28) comprises
friction materials and springs.
4. The clutch assembly (10) of claim , wherein the pulley (24) is separated from the
clutch armature (28).
5. The clutch assembly (10) of claim 1, further comprising a clutch housing (20).
6. The clutch assembly (10) of claim 5, wherein the clutch coil (30) is mounted in
the clutch rotor (26) and is disposed between the clutch housing (20) and the clutch rotor (26) in
a direction along the longitudinal axis (36) of the input shaft (18).
7. The clutch assembly (10) of claim 1, wherein the diameter of the pulley (24) is
smaller than the diameter of the clutch coil (30).
8. The clutch assembly (10) of claim 5, further comprising at least two bearings
(38,40) disposed between the clutch housing (20) and the input shaft (18).
9. The clutch assembly (10) of claim 8, wherein at least a portion of the pulley (24)
circumferentially surrounds one of the at least two bearings (38, 40) and wherein the other of the
at least two bearings (38, 40) is not configured to support a radial load exerted by the pulley (24).
10. The clutch assembly (10) of claim 1, wherein the pulley (24) is not integrated into
the rotor (26).
11. The clutch assembly (10) of claim 1, wherein the pulley (24) is independent of the
torque capacity of the clutch rotor (26), clutch armature (28), and clutch coil (30).
12. The clutch assembly (10) of claim 1, wherein the rotational speed of the clutch
armature (28) is less than the rotational speed of the first shaft (18) when the clutch assembly
(20) is disengaged.
13. The clutch assembly (10) of claim 1, wherein the rotational speed of the clutch
armature (28) is substantially the same as the rotational speed of the first shaft (18) when the
clutch assembly (10) is engaged.
14. The clutch assembly (10) of claim 1, wherein the rotational speed of the clutch
rotor (26) is substantially the same as the rotational speed of the first shaft (18) when the clutch
assembly (10) is disengaged.
15. The clutch assembly (10) of claim 1, wherein the clutch armature (28) is separated
from the pulley (24).
16. The clutch assembly (10) of claim 1, wherein the clutch coil (30) is separated
from the pulley (24).
17. The clutch assembly (10) of claim 5, wherein the clutch housing (20) is smaller in
diameter at a first end (32) proximate the pulley (24) and larger in diameter at a second end (34)
proximate the supercharger (12).
18. A supercharger (12), comprising:
a clutch assembly (10, 110) comprising:
a clutch housing (20);
a first shaft (18) having a longitudinal axis (36);
a pulley (24) connected to the first shaft (18);
a clutch rotor (26) connected to the first shaft ( 8), wherein the clutch
rotor (26) rotates around the longitudinal axis (36);
a clutch armature (28) unconnected to the first shaft (18), wherein the
clutch armature (28) rotates around the longitudinal shaft (36);
a clutch coil (30) spaced along the longitudinal axis (36) from the pulley
(24); and
a supercharger housing (16);
a plurality of supercharger rotors (14) disposed within the supercharger housing
(16);
a second shaft (22) configured to drive rotation of the plurality of supercharger
rotors (14);
a step-up gear (50) connected to the second shaft (22);
wherein the diameter of the pulley (24) is independent of the diameters of the
clutch rotor (26), the clutch armature (28), and the clutch coil (30).