Elastomeric coupling for supercharger

A coupling assembly arranged between an input shaft and a rotor shaft of a supercharger can include a first hub, a second hub and an elastomeric coupling. The first hub can be coupled to the input shaft and include a first plurality of coupling pins extending therefrom. The second hub can be coupled to the input shaft and include a second plurality of coupling pins extending therefrom. The elastomeric coupling can include a coupling body having a series of openings. The first and second coupling pins can be alternately received by the respective openings. The elastomeric coupling can be configured to absorb torsional variations from the input shaft.

FIELD

The present disclosure relates generally to superchargers and more particularly to an elastomeric coupling between an input shaft and a rotor shaft on a 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.

In some examples, superchargers such as the Roots-type blower can create unwanted noise. For example, Roots-type blower noise may be classified as either of two types. The first is solid borne noise caused by rotation of timing gears and rotor shaft bearings subjected to fluctuating loads (the firing pulses of the engine), and the second is fluid borne noise caused by fluid flow characteristics, such as rapid changes in fluid (air) velocity. The present disclosure is primarily directed toward the solid borne noise. More particularly the present disclosure can minimize the “bounce” of the timing gears during times of relatively low speed operation, when the blower rotors are not “under load”. In this regard, it is important to isolate the fluctuating input to the supercharger from the timing gears. In other examples it is desirable to account for misalignment and/or runout between the input shaft and rotor shaft. In some operating conditions, decoupling the supercharger inertia from the input belt system can help reduce unwanted noise generated in the belt system.

SUMMARY

A coupling assembly arranged between an input shaft and a rotor shaft of a supercharger can include a first hub, a second hub and an elastomeric coupling. The first hub can be coupled to the input shaft and include a first plurality of coupling pins extending therefrom. The second hub can be coupled to the input shaft and include a second plurality of coupling pins extending therefrom. The elastomeric coupling can include a coupling body having a series of openings. The first and second coupling pins can be alternately received by the respective openings. The elastomeric coupling can be configured to absorb torsional variations from the input shaft.

According to additional features, the elastomeric coupling can further include a plurality of spokes extending from the central hub. Each spoke can have a corresponding mounting portion thereon. Each mounting portion defines a respective opening thereon. Opposite radial ends of the mounting portions can comprise bumpers thereon. Adjacent bumpers can be configured to engage each other. The elastomeric coupling can be unitary. In one example the elastomeric coupling can be formed of elastomeric material. The elastomeric coupling can be formed of thermoplastic polyester elastomer such as Hytrel® manufactured by DuPont™. In another example, the central hub, the spokes and the mounting portions can be formed of Polyether ether ketone (PEEK) and the bumpers can be formed of Hytrel®.

According to still other features, the first hub can define a first series of counter-recesses formed therein. The first series of counter-recesses can accommodate a terminal end portion of the respective second plurality of coupling pins. Each counter-recess of the first series of counter-recesses is arcuately shaped. The second hub can define a second series of counter-recesses formed therein. The second series of counter-recesses can accommodate a terminal end portion of the respective first plurality of coupling pins. Each counter-recess of the second series of counter-recesses is arcuately shaped.

A coupling assembly arranged between an input shaft and a rotor shaft of a supercharger can include a first hub, a second hub and an elastomeric coupling. The first hub can be coupled to the input shaft and have a first plurality of coupling pins extending therefrom. The second hub can be coupled to the input shaft and have a second plurality of coupling pins extending therefrom. The elastomeric coupling can have a coupling body including a central hub, a plurality of spokes and a corresponding pair of bumpers. The plurality of spokes can extend radially from the central hub and each have a mounting portion formed therein. Each mounting portion can define an opening that alternately receives the first and second plurality of coupling pins. The corresponding pair of bumpers can be formed on each mounting portion. Opposing bumpers can engage each other upon rotation of the first hub in a first direction and rotation of the second hub in a second opposite direction. The elastomeric coupling can be configured to absorb torsional variations from the input shaft.

According to additional features, the first hub can define a first series of counter-recesses formed therein. The first series of counter-recesses can accommodate a terminal end portion of the respective second plurality of coupling pins. Each counter-recess of the first series of counter-recesses is arcuately shaped. The second hub can define a second series of counter-recesses formed therein. The second series of counter-recesses can accommodate a terminal end portion of the respective first plurality of coupling pins. Each counter-recess of the second series of counter-recesses is arcuately shaped. In one example the elastomeric coupling can be formed of elastomeric material. The elastomeric coupling can be formed of thermoplastic polyester elastomer such as Hytrel® manufactured by DuPont™. In another example, the central hub, the spokes and the mounting portions can be formed of Polyether ether ketone (PEEK) and the bumpers can be formed of Hytrel®.

DETAILED DESCRIPTION

With initial reference toFIG. 1, a schematic illustration of an exemplary intake manifold assembly, including a Roots blower supercharger and bypass valve arrangement is shown. An engine10can include a plurality of cylinders12, and a reciprocating piston14disposed within each cylinder and defining an expandable combustion chamber16. The engine10can include intake and exhaust manifold assemblies18and20, respectively, for directing combustion air to and from the combustion chamber16, by way of intake and exhaust valves22and24, respectively.

The intake manifold assembly18can include a positive displacement rotary blower26, or supercharger of the Roots type. Further description of the rotary blower26may be found in commonly owned U.S. Pat. Nos. 5,078,583 and 5,893,355, which are expressly incorporated herein by reference. The blower26includes a pair of rotors28and29, each of which includes a plurality of meshed lobes. The rotors28and29are disposed in a pair of parallel, transversely overlapping cylindrical chambers28cand29c, respectively. The rotors28and29may be driven mechanically by engine crankshaft torque transmitted thereto in a known manner, such as by a drive belt (not specifically shown). The mechanical drive rotates the blower rotors28and29at a fixed ratio, relative to crankshaft speed, such that the displacement of the blower26is greater than the engine displacement, thereby boosting or supercharging the air flowing to the combustion chambers16.

The blower26can include an inlet port30, which receives air or air-fuel mixture from an inlet duct or passage32, and further includes a discharge or outlet port34, directing the charged air to the intake valves22by means of a duct36. The inlet duct32and the discharge duct36are interconnected by means of a bypass passage, shown schematically at reference38. If the engine10is of the Otto cycle type, a throttle valve40can control air or air-fuel mixture flowing into the intake duct32from a source, such as ambient or atmospheric air, in a well know manner. Alternatively, the throttle valve40may be disposed downstream of the supercharger26.

A bypass valve42is disposed within the bypass passage38. The bypass valve42can be moved between an open position and a closed position by means of an actuator assembly44. The actuator assembly44can be responsive to fluid pressure in the inlet duct32by a vacuum line46. The actuator assembly44is operative to control the supercharging pressure in the discharge duct36as a function of engine power demand. When the bypass valve42is in the fully open position, air pressure in the duct36is relatively low, but when the bypass valve42is fully closed, the air pressure in the duct36is relatively high. Typically, the actuator assembly44controls the position of the bypass valve42by means of a suitable linkage. The bypass valve42shown and described herein is merely exemplary and other configurations are contemplated. In this regard, a modular (integral) bypass, an electronically operated bypass, or no bypass may be used.

With specific reference now toFIG. 2, an input section48of the blower26is shown. The input section48can include a housing member50, which forms a forward end of the chambers28cand29c. Attached to the housing member50is a forward housing52within which is disposed an input shaft54. The input shaft54is supported within the forward housing52by at least one bearing56. Rotatably supported by the housing member50is a rotor shaft60, upon which is mounted the blower rotor28(seeFIG. 1). A coupling assembly62couples the input shaft54to the rotor shaft60. In one example, a first hub64can couple the input shaft54to the coupling assembly62on a first end and a second hub66can couple the rotor shaft60to the coupling assembly62on an opposite end. While not specifically shown a first timing gear may be mounted on a forward end of the rotor shaft. The first timing gear may define teeth that are in meshed engagement with gear teeth of a second timing gear that is mounted on the second rotor shaft. The second rotor shaft would be in driving engagement with the blower rotor29.

In one configuration, positive torque is transmitted from an internal combustion engine (of the periodic combustion type) to the input shaft54by any suitable drive means, such as a belt and pulley drive system (not shown herein). Torque is transmitted from the input shaft54to the rotor shaft60through the coupling assembly62. The coupling assembly62of the present disclosure provides torsional damping and can further account for misalignment between the input shaft54and the rotor shaft60. When the engine10is driving the timing gears and the blower rotors28and29, such is considered to be transmission of positive torque. On the other hand, whenever the momentum of the rotors28and29overruns the input from the input shaft54, such is considered to be the transmission of negative torque.

With additional reference now toFIGS. 3-8, the coupling assembly62constructed in accordance to one example of the present disclosure will be described in greater detail. The coupling assembly62can generally include an elastomeric coupling80, a first plurality of coupler pins88and a second plurality of coupler pins90. In the example shown, the first and second plurality of coupler pins88and90are constructed similarly.

The elastomeric coupling80can be formed by a combination of Polyether ether ketone (PEEK) and Hytrel®. Hytrel® is manufactured by DuPont™. In another example, the elastomeric coupling80can be unitarily formed of elastomeric material such as Hytrel® or Nylon 46. In another example, the elastomeric coupling80can be formed of Vamac® manufactured by DuPont™. In one example, the elastomeric material can be a synthetic elastomeric (elastic polymer). The elastomeric coupling80can be molded or poured as an amorphous liquid. The elastomeric material can absorb the rotational energy from the coupler pins88and90during operation of the rotary blower26to provide dampening. The elastomeric coupling80is configured to absorb torsional variations from the input shaft54.

The elastomeric coupling80generally includes a coupling body100(FIG. 5A) having a plurality of spokes110extending from a central hub112. Each of the spokes110extend from the central hub112to mounting portions120. Each of the mounting portions120define an opening122. The openings122are configured to selectively receive the coupler pins88and90in alternating fashion. Opposite radial ends of the mounting portions120include bumpers126. During use, torsional loads can be transferred from the respective first and second coupler pins88and90through the coupling body100. In doing so, mounting portions120associated with the coupler pins88can move in a first rotatable direction while mounting portions120associated with the coupler pins90can move in a second opposite rotatable direction. In doing so, adjacent bumpers126can be configured to move toward each other and eventually engage each other (FIG. 5B) and further dampen load. The spokes110can elastically deform to allow movement of the mounting portions120and bumpers126toward each other. In one configuration, the central hub112, spokes110and mounting portions120can be formed of PEEK and the bumpers126can be overmolded and/or formed of Hytrel®. An exemplary elastomeric coupling shown in the upper left ofFIG. 9illustrates the distinct materials.

With particular reference now toFIGS. 3-8, the first hub64will be described in greater detail. In general, the first hub64is used to couple the input shaft54to the coupling assembly62. The second hub66is used to couple the rotor shaft60to the coupling assembly62. The first hub64and the second hub66are constructed similarly. In this regard, only the first hub64will be described. The first hub64can generally include a first hub body212including a central hub body214and a distal protruding section216. The central hub body214includes a plurality of apertures220that receive coupler pins88therein. A series of counter-recesses230are formed in the central hub body214. The counter-recesses are formed in an arcuate shape. The counter-recesses230are arranged to accommodate a terminal end portion of the coupler pins90(FIG. 2). The arcuate shape can accommodate relative rotational movement of the coupler pins90in the counter-recesses230. A central bore236is formed through the first hub212. In one example, the input shaft54can be press-fit into the central bore236.

In an assembled position, the coupler pins90extending from the second hub66can extend through the respective openings122of the coupling80. Similarly, the coupler pins88extending from the first hub64can extend through the respective openings122(again coupler pins88and90alternate) of the coupling80. During operation, the coupling assembly62provides torsional dampening between the input shaft54to the rotor shaft60. In this regard, the mounting portions120provide parallel springs for the first hub64and the second hub66as they absorb rotational energy from the coupler pins88and90. In this regard, the coupling assembly62provides damping to provide misalignment degree of freedom, torsional rate reduction and torsional dampening.

FIG. 9shows a collection of elastomeric couplings300constructed in accordance to additional features. As illustrated, various elastomeric couplings may provide dedicated spokes that lead to mounting portions having various shapes. The respective bumper portions can be configured with various geometries suitable for specific applications. As can be appreciated, some spoke geometries having thicker material may provide greater resistance to absorb rotational energy.

The foregoing description of the examples 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 example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, 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.