Patent Publication Number: US-2016237885-A1

Title: Supercharger having pre-boosting configuration

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/US2014/058779 filed on Oct. 2, 2014, which claims the benefit of U.S. patent application Ser. No. 61/896,731 filed on Oct. 29, 2013 and U.S. patent application Ser. No. 61/932,440 filed on Jan. 28, 2014. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates generally to superchargers and more particularly to a clutched supercharger having an electric motor providing a driving input to a rotor shaft of the supercharger. 
     BACKGROUND 
     Rotary blowers of the type to which the present disclosure relates are referred to as “superchargers” because they effectively super charge the intake of the engine. One supercharger configuration is generally referred to as a Roots-type blower that transfers volumes of air from an inlet port to an outlet port. A Roots-type blower includes a pair of rotors which must be timed in relationship to each other, and therefore, are driven by meshed timing gears which are potentially subject to conditions such as gear rattle and bounce. Typically, a pulley and belt arrangement for a Roots blower supercharger is sized such that, at any given engine speed, the amount of air being transferred into the intake manifold is greater than the instantaneous displacement of the engine, thus increasing the air pressure within the intake manifold and increasing the power density of the engine. 
     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. An engageable/disengageable clutch may be disposed in series between the supercharger input (e.g., a belt driven pulley) and the rotors of the supercharger. In some examples, a clutched configuration may create undesirable stick-slip conditions. 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     SUMMARY 
     A supercharger constructed in accordance to one example of the present disclosure can include a shaft portion connected to a pulley. A pair of supercharger rotors can be arranged for concurrent rotation with respective rotor shafts. A clutch rotor can be mounted to the shaft portion. The clutch rotor can rotate around a longitudinal axis. A clutch armature can be mounted to a drive shaft and unconnected to the shaft portion. The clutch armature can be configured to rotate around the longitudinal axis. The clutch rotor and the clutch armature can selectively cooperate in an engaged position and a disengaged position. In the engaged position, the clutch rotor and the clutch armature rotate together. An electric motor can have an output that provides a rotational input to one of the rotor shafts. 
     According to additional features, the electric motor can be mounted to a housing of the supercharger. The output of the electric motor can comprise an electric motor output shaft. The electric motor output shaft can rotate around a first axis. The rotor shaft can rotate around a second axis. The first and second axes can be collinear. The electric motor can rotate the supercharger rotors at substantially one-third of peak engagement speed. The electric motor can be configured to rotate the supercharger rotors prior to engagement of the clutch rotor and the clutch armature thereby reducing an initial speed differential between the clutch rotor and the clutch armature. 
     According to other features, the supercharger can further include a clutch coil that is spaced along the longitudinal axis from the pulley. The clutch rotor can be magnetized by the clutch coil. The supercharger can further comprise a clutch housing. The clutch coil can be mounted in the clutch rotor and be disposed between the clutch housing and the clutch rotor in a direction along the longitudinal axis. The electric motor can be configured to provide a constant rotational input to the supercharger rotors when the first shaft portion is being rotated. 
     A supercharger constructed in accordance to additional features of the present disclosure can include a first shaft portion connected to a pulley and configured to rotate around a longitudinal axis. A pair of rotors can each have a plurality of meshed lobes. A drive shaft can drive the pair of rotors. A clutch assembly can selectively couple the first shaft portion and the drive shaft between a disengaged position and an engaged position. An electric motor can drive the pair of rotors and be configured to reduce a speed differential between the first shaft portion and the drive shaft upon movement from the disengaged position to the engaged position. 
     According to other features, the clutch assembly can further include a clutch rotor and a clutch armature. The clutch rotor can be mounted to the first shaft portion, wherein the clutch rotor rotates around the longitudinal axis. A clutch armature can be mounted to a drive shaft and be unconnected to the first shaft portion in the disengaged position. The clutch armature can be configured to rotate around the longitudinal axis. The clutch rotor and the clutch armature can selectively cooperate in the engaged position and the disengaged position. In the engaged position, the clutch rotor and the clutch armature rotate together. 
     According to additional features, the supercharger can include a clutch coil spaced along the longitudinal axis from the pulley. The clutch rotor can be magnetized by the clutch coil. The supercharger can further include a clutch housing. The clutch coil is mounted in the clutch rotor and is disposed between the clutch housing and the clutch rotor in a direction along the longitudinal axis. 
     According to other features, the electric motor can be mounted to a housing of the supercharger. The electric motor can have an output comprising an electric motor output shaft. The electric motor output shaft can rotate around a first axis. One of the rotors can comprise a rotor shaft that rotates around the second axis. The first and second axes are collinear. The electric motor can rotate the supercharger rotors at substantially one-third of peak engagement speed. The electric motor can be configured to rotate the supercharger rotors prior to engagement of the clutch rotor and the clutch armature thereby reducing an initial speed differential between the clutch rotor and the clutch armature. 
     A supercharger constructed in accordance to another example of the present disclosure can include a first shaft portion connected to a pulley and configured to rotate around a longitudinal axis. A pair of supercharger rotors can each have a plurality of meshed lobes and each configured for concurrent rotation with a respective rotor shaft. A drive shaft can drive the pair of rotors. A clutch assembly can selectively couple the first shaft portion and the drive shaft between a disengaged position and an engaged position. The clutch assembly can include a clutch rotor and a clutch armature. The clutch rotor can be mounted to the first shaft portion. The clutch rotor can rotate around the longitudinal axis. The clutch armature can be mounted to a drive shaft and be unconnected to the first shaft portion in the disengaged position. The clutch armature can be configured to rotate around the longitudinal axis. The clutch rotor and the clutch armature can selectively cooperate in the engaged position and the disengaged position. In the engaged position, the clutch rotor and the clutch armature rotate together. An electric motor can drive the pair of supercharger rotors and be configured to reduce a speed differential between the first shaft portion and the drive shaft upon movement from the disengaged position to the engaged position. The electric motor can be configured to rotate the supercharger rotors prior to engagement of the clutch rotor and the clutch armature thereby reducing an initial speed differential between the clutch rotor and the clutch armature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a cross-sectional view of an exemplary supercharger incorporating a clutch assembly and electric motor constructed in accordance to one example of the present disclosure; 
         FIG. 2  is an exploded perspective view of a clutch armature, clutch rotor, and clutch coil of a clutch assembly in accordance with one example of the present disclosure; 
         FIG. 3  is an exploded perspective view of a portion of the clutch assembly in accordance with one example of the present disclosure; 
         FIG. 4  is a cross-sectional view of an exemplary supercharger incorporating a clutch assembly and electric motor constructed in accordance to another example of the present disclosure; 
         FIG. 5  is a cross-sectional view of an exemplary supercharger incorporating a clutch assembly and electric motor constructed in accordance to another example of the present disclosure; 
         FIG. 6  is a cross-sectional view of an exemplary supercharger incorporating a clutch assembly and electric motor constructed in accordance to another example of the present disclosure; and 
         FIG. 7  is a cross-sectional view of an exemplary supercharger incorporating a clutch assembly and electric motor constructed in accordance to another example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1-3 , a supercharger constructed in accordance with one example of the present disclosure is shown and generally identified at reference  12 . The supercharger  12  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. 
     The supercharger  12  of the intake manifold may be any positive displacement pump, including the Roots type blower supercharger 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 compressor or any other type of positive displacement pump. In accordance with an embodiment of the invention, the supercharger  12  may include a pair of rotors  14 , each having a plurality of meshed lobes. The rotors  14  each have rotor shafts  15  and 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 such as 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 a drive 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 that 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. 
     The supercharger  12  can include a clutch assembly  20  having a clutch housing  21 , a shaft portion  22 , a pulley  24 , a clutch rotor  26 , a clutch armature  28 , and a clutch coil  30 . The clutch housing  21  may be configured to house other components of the clutch assembly  20 . The clutch housing  21  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 to the pulley  24 . The second end  34  may be proximate to the main housing  16  of the supercharger  12 . 
     The shaft  22  can rotate about a longitudinal axis  36 . In the example shown, the shaft  22  is supported by a first bearing  38  and a second bearing  40 . Other configurations are contemplated. The pulley  24  may be configured to transmit torque from the engine crankshaft (not shown) to the shaft  22  during engagement of the clutch assembly  20 . In the example shown, the pulley  24  can be coupled to the shaft  22 . In this regard, the pulley  24  can be disposed externally to the shaft  22  in accordance with one example of the present disclosure. The pulley  24  can be disposed at an end of the shaft  22  and may circumferentially surround the shaft  22 . The pulley  24  can be external to the clutch housing  21 . In addition, the pulley  24  can be axially spaced along the longitudinal axis  36  from the clutch housing  21 . The first bearing  38  that is disposed between the clutch housing  21  and the shaft  22  may be proximate to the pulley  22 . The second bearing  40  may be disposed between the clutch housing  21  and the shaft  22  closer toward the main housing  16  of the supercharger  12 . The pulley  24  may be separated from other components of the clutch assembly  20 . For example the pulley  24  may be separated from the clutch armature  28 . 
     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 example of the present disclosure. The pulley  24  may have a diameter that is between about 45 mm and about 85 mm in accordance with one example of the present disclosure. 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 example of the present disclosure, as the pulley  24  may not surround the clutch coil  30  in accordance to one configuration. The pulley  24  may also not be integrated with the clutch rotor  26  in accordance with an example of the present disclosure. 
     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 the second shaft portion  22 B and or the pulley  24 . The clutch rotor  26  may rotate around the longitudinal axis  36  of the shaft  22 . The clutch rotor  26  is not connected to the drive shaft  18  of the supercharger as may be conventional in small pulley designs. The clutch rotor  26  may comprise steel in one configuration. The clutch rotor  26  can be formed of other materials. 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 example of the present disclosure. Because the clutch rotor  26  may be connected to the shaft  22  and/or the pulley  24 , the clutch rotor  26  may always maintain the same rotational speed as the pulley  24  in accordance to one configuration of the present disclosure. In this regard, the clutch rotor  26  may rotate at a rotational speed that is substantially the same as the rotational speed of the shaft  22  even with the clutch assembly  20  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 . 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 . 
     The clutch armature  28  can rotate around the longitudinal axis  36 . The clutch armature  28  can 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 adjacent to the clutch rotor  26  along the longitudinal axis  26 . 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 frictional material. The clutch armature  28  may have a second face  48  that is configured to face the supercharger  12 . The second face  48  can oppose the first face  46 . 
     The clutch armature  28  may be connected to the drive shaft  18  of the supercharger  12  through a spline and bolt. The clutch armature  28  may contain speed sensitive components in one example. The rotational speed of the clutch armature  28  may be less than the rotational speed of the shaft  22  when the clutch assembly  20  is disengaged. Accordingly, the clutch armature  28  may be configured to coast down to a stop when the clutch assembly  20  is disengaged, rather than always having to maintain the same rotational speed of the pulley  24 . 
     The clutch armature  28  may not be connected to the shaft  22  and or the pulley  24  in one configuration. Instead, the clutch armature  28  may be separated from the pulley  24  in accordance with one example. The clutch armature  20  may be connected to the drive shaft  18  of the supercharger  12 . The rotational speed of the clutch armature  28  may be substantially the same as the rotational speed of the shaft  22  when the clutch assembly  20  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, the clutch armature  28  may not be connected to shaft  22  and/or the 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  21  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 . 
     The clutch coil  30  can include 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 the 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  20 , the clutch armature  28  may be free to turn with the drive shaft  18  of the supercharger  12 . 
     The clutch coil  30  may not be surrounded by the 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  21  in a direction along the longitudinal axis  36 . The clutch coil  30  may be spaced along the longitudinal axis  36  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  21  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 . 
     In one configuration, 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  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 the 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  20 . 
     A supercharger  12  including the clutch assembly  20  in accordance to one example may further include a step-up gear  50  connected to the drive 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 the drive shaft  18  and the step up gear  50  by means of which the supercharger  12  may receive input drive torque. A supercharger  12  in accordance with one example of the present disclosure may comprise the clutch assembly  20 , pair of rotors  14 , housing  16  that houses the pair of rotors  14 , drive shaft  18  configured to drive rotation of the pair of rotors  14  and step-up gear  50  connected to the drive shaft  18 . 
     The supercharger  12  according to the present disclosure can incorporate an electric motor  70 . In this regard, the electric motor  70  can have an electric motor output shaft  72  that connects to and provides a driving rotational input to the rotor shaft  15 . In other examples, the output shaft of the electric motor  70  can be a common shaft to the rotor shaft  15 . In still other examples, one or more intermediate gears may be provided between the electric motor output shaft  72  and the rotor shaft  15 . In the example shown, at least one of the rotor shaft  15  and the electric motor output shaft  72  can extend through an opening  76  in the housing  16  of the supercharger  12 . In one example, the electric motor  70  can be coupled to the supercharger  12  such as by fasteners engaged to the housing  16 . While the particular example described herein is directed to superchargers having downstream throttles, other applications are contemplated. 
     The electric motor  70  can operate to rotate the rotor shaft  15  and therefore the rotors  14  to a predetermined speed. In this regard, the electric motor  70  can provide a pre-boosting configuration to the supercharger  12 . In one configuration, the electric motor shaft  72  and the rotor shaft  15  can be collinear such that they rotate around a common axis. Other configurations are contemplated. In one example, the electric motor  70  can reduce or eliminate low speed clutch engagements. Explained further, the electric motor  70  can rotate the supercharger rotors  14  to a predetermined speed causing the clutch armature  28  to be rotating (rather than static) when the clutch assembly  20  is initially engaged. In this regard, the speed differential between the clutch rotor  26  (rotating with the shaft  22 ) and the clutch armature  28  can be reduced at initial engagement of the clutch assembly  20 . According to one configuration, the electric motor  70  can rotate the rotors  14  at around one-third of peak engagement speed. In one configuration, the electric motor  70  can be configured to provide a constant rotational input to the shaft  15  when the pulley  24  is being rotated. Other configurations are contemplated. 
     The electric motor  70  can be powered by the vehicles electrical system. A number of advantages can be realized with the electric motor  70 . For example, undesirable conditions such as stick-slip can be limited. Because a speed differential between the clutch rotor  26  and the clutch armature  28  is reduced at initial clutch engagement, less wear is realized between the clutch rotor  26  and the clutch armature  28 . In this regard, clutch life and clutch control can be increased. Furthermore, for similar reasons, clutch noise can be reduced. 
     While the particular example shown includes an electric motor  70  having an electric motor output shaft  72  that couples mechanically to the rotor shaft  15 , other configurations are contemplated. For example, other hysteresis or non-contact methods may be implemented for communicating a rotational input from an electric motor to rotational movement of the supercharger rotors  14 . In one example, a non-contact magnetic coupling may be incorporated. Other configurations are contemplated. 
     Turning now to  FIG. 4 , the electric motor  70  is shown coupled to the supercharger  12  according to additional features. The electric motor  70  can include an output gear  120  disposed on an output shaft  122 . The rotor shaft  15  can extend through an opening  76  in the housing  16  of the supercharger. The rotor shaft  15  can include a gear  124  disposed thereon. A power transfer mechanism  110  can be disposed between the output gear  120  of the electric motor  70  and the gear  124  on the rotor shaft  15 . The power transfer mechanism  110  can include a gearing configuration, a pulley or other configuration for transferring a rotory output of the electric motor output shaft  122  to a rotory input of the rotor shaft  15 . Other configurations are contemplated. 
     With reference to  FIG. 5 , the electric motor  70  is shown coupled to the supercharger  12  according to additional features. The electric motor  70  can include the output gear  120  disposed on the output shaft  122 . The drive shaft  18  can have a gear  130  disposed thereon. A power transfer mechanism  160  can be disposed between the output gear  120  of the electric motor  70  and the gear  130  on the drive shaft  18 . The power transfer mechanism  160  can include a gearing configuration, a pulley or other configuration for transferring a rotory output of the electric motor output shaft  122  to the gear  130  of the drive shaft  18 . Other configurations are contemplated. 
     With reference to  FIG. 6 , the electric motor  70  is shown coupled to the supercharger  12  according to additional features. The electric motor  70  can include the output gear  120  disposed on the output shaft  122 . The drive shaft  18  can have a gear  182  disposed thereon. The output gear  120  can be splined to the gear  182  for transfering a rotory output of the electric motor output shaft  122  to the drive shaft  18 . It will be appreciated that an intermediate gear or transfer mechanism may be configured between the output gear  120  and the gear  182 . Other configurations are contemplated. 
     With reference to  FIG. 7 , the electric motor  70  is shown coupled to the supercharger  12  according to additional features. The electric motor  70  can include the output gear  120  disposed on the output shaft  122 . The output gear  120  can be coupled to any internal gearing generally identified at  190  of the supercharger  12 . A power transfer device  212  may be coupled between the output gear  120  and the internal gearing  190 . In this regard, the electric motor  70  can be arranged to couple directly or indirectly to any rotating component of the supercharger  12 . Other configurations are contemplated. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.