HIGH PRESSURE ROTOR SEAL CONFIGURATION FOR SUPERCHARGER

A supercharger that receives and/or generates high pressure boost air and contains gear lubrication includes a housing, a rotor coupled to a rotor shaft rotatably supported in the housing, and a high pressure rotor seal disposed about the rotor shaft. The high pressure rotor seal includes a primary lip configured to contact the rotor shaft and be exposed to the gear lubrication, and at least one boost pressure blocking lip configured to contact the rotor shaft and maintain a seal against the rotor shaft when the high pressure boost air acts thereon.

FIELD

The present disclosure relates generally to superchargers and more particularly to superchargers incorporating a high pressure rotor seal configuration.

BACKGROUND

Energy efficient engines of reduced size are desirable for fuel economy and cost reduction. However, smaller engines provide less torque than larger engines. To increase the torque capacity available from smaller engines, boosting systems are incorporated to boost the air pressure at the engine intake to increase the torque available from the engine. Some conventional boosting systems include both a mechanically driven supercharger and an exhaust gas-driven turbocharger.

A turbocharger typically includes a turbine exposed to engine exhaust flow and a compressor positioned in the air intake of the engine. Exhaust flow from the engine turns the turbine which transfers torque to the compressor causing the compressor to boost the intake air pressure. Turbochargers can be efficient but have the disadvantage of lag, which refers to a delay in providing boost pressure. Because the turbocharger depends on energy from the exhaust to provide the boost pressure, high levels of boost are not immediately provided when the engine is operating at lower speeds. Instead, full levels of boost are not provided until the engine reaches a high enough speed where the exhaust has sufficient energy to adequately drive the turbocharger.

A supercharger is driven by torque drawn directly from the engine, which enables the supercharger to provide a rapid boost in pressure without the type of delays associated with turbochargers. However, superchargers are typically designed with a fixed gear ratio that under normal driving conditions generates excess air flow that is typically routed through a bypass and recirculated through the supercharger, which results in energy loss.

To overcome the above issues, compound boost systems have been introduced that include both turbochargers and superchargers. In this type of system, the turbocharger is typically used as the primary boost producer, and the supercharger is designed to supplement the turbocharger to compensate for lag. However, in systems where the turbocharger is located upstream of the supercharger, the turbocharger will provide an elevated inlet pressure condition to the supercharger, which elevates the pressure applied to seals in the supercharger. As such, the primary lip of the seal may be crushed or rendered ineffective, which may result in oil leakage.

Accordingly, it is desirable to provide an improved seal configuration for boosting systems that may be used in compound boosting systems.

SUMMARY

In one aspect, a high pressure rotor seal for a supercharger that receives and/or generates high pressure boost air and contains gear lubrication, is provided. The rotor seal includes a primary lip configured to contact a rotor shaft of the supercharger and be in contact with the gear lubrication, and at least one blocking lip configured to contact the rotor shaft of the supercharger. The at least one blocking lip is configured to maintain a seal against the rotor shaft when the high pressure boost air acts thereon.

In addition to the foregoing, the described high pressure rotor seal may include one or more of the following features: wherein the at least one blocking lip includes two blocking lips; wherein the at least one blocking lip includes three blocking lips; a backing plate disposed adjacent the primary lip, the backing plate configured to provide structural support to the primary lip and prevent the primary lip from being crushed under excessive boost pressure; wherein the backing plate is curved; wherein the curved backing plate generally follows a curvature of the primary lip; a cage, wherein the primary lip and the at least one blocking lip are at least partially secured within the cage; wherein the cage includes a first flange and a second flange, at least a portion of the primary lip and the at least one blocking lip disposed between the first and second flanges; wherein the primary lip includes a proximal portion disposed between the first and second flanges, and a distal portion extending toward the rotor shaft and a bearing cavity of the supercharger; wherein each blocking lip includes a proximal portion disposed between the first and second flanges, and a distal portion extending toward the rotor shaft and a rotor cavity of the supercharger; and a spacer disposed between the proximal portion of the primary lip and the proximal portion the at least one blocking lip, and hydrodynamic grooves formed on a first side of the primary lip, the hydrodynamic grooves configured to pump oil across the rotor seal.

In another aspect, a supercharger that receives and/or generates high pressure boost air and contains gear lubrication, is provided. The supercharger includes a housing, a rotor coupled to a rotor shaft rotatably supported in the housing, and a high pressure rotor seal disposed about the rotor shaft. The high pressure rotor seal includes a primary lip configured to contact the rotor shaft and be exposed to the gear lubrication, and at least one boost pressure blocking lip configured to contact the rotor shaft and maintain a seal against the rotor shaft when the high pressure boost air acts thereon.

In addition to the foregoing, the described supercharger may include one or more of the following features: an inlet port formed in a forward end of the housing, the inlet port configured to receive at least one of air, an air-fuel mixture, and the high pressure boost air; wherein the at least one blocking lip includes two blocking lips; wherein the at least one blocking lip includes three blocking lips; wherein the high pressure rotor seal further comprising a backing plate disposed adjacent the primary lip, the backing plate configured to provide structural support to the primary lip and prevent the primary lip from being crushed under excessive boost pressure; wherein the backing plate is curved and generally follows a curvature of the primary lip; wherein the high pressure rotor seal further comprising a cage, wherein the primary lip and the at least one blocking lip are at least partially secured within the cage; wherein the cage includes a first flange and a second flange, at least a portion of the primary lip and the at least one blocking lip disposed between the first and second flanges; and wherein the primary lip includes a proximal portion disposed between the first and second flanges, and a distal portion extending toward the rotor shaft and a bearing cavity of the supercharger, wherein each blocking lip includes a proximal portion disposed between the first and second flanges, and a distal portion extending toward the rotor shaft and a rotor cavity of the supercharger, and a spacer is disposed between the proximal portion of the primary lip and the proximal portion the at least one blocking lip.

In yet another aspect, a high pressure rotor seal for a supercharger that receives and/or generates high pressure boost air and contains gear lubrication, is provided. The rotor seal includes a seal body defining an outer surface and an inner surface, a primary lip extending from the seal body and configured to contact a rotor shaft of the supercharger and be in contact with the gear lubrication, and a rigid guide plate disposed at least partially within the seal body against the seal body inner surface. The rigid guide plate is configured to prevent the high pressure rotor seal from being crushed under the high pressure boost air.

In addition to the foregoing, the described high pressure rotor seal may include one or more of the following features: wherein the primary lip extends toward an air side of the supercharger; wherein the primary lip is curved and extend towards a bearing cavity of the supercharger; wherein the rigid guide plate comprises a generally annular rim, a first flange, and a second flange; wherein the first flange extends radially outward from the rim, and the second flange extends radially inward from the rim; wherein the second flange is curved and generally follows a curvature of the primary lip; wherein a gap is defined between an end of the second flange and the rotor shaft, the gap configured to allow the lubrication to flow to the primary lip; a rigid cage disposed at least partially within the body; wherein the primary lip includes hydrodynamic grooves formed on a first side of the primary lip, the hydrodynamic grooves configured to pump oil across the rotor seal; and wherein the rigid guide plate is pressed into an inner diameter of the body.

In yet another aspect, a supercharger that receives and/or generates high pressure boost air and contains gear lubrication, is provided. The supercharger include a housing, a rotor coupled to a rotor shaft rotatably supported in the housing, and a high pressure rotor seal disposed about the rotor shaft. The high pressure rotor seal includes a seal body defining an outer surface and an inner surface, a primary lip extending from the seal body and configured to contact the rotor shaft and be in contact with the gear lubrication, and a rigid guide plate disposed at least partially within the seal body against the seal body inner surface. The rigid guide plate is configured to prevent the high pressure rotor seal from being crushed under the high pressure boost air.

In addition to the foregoing, the described supercharger may include one or more of the following features: an inlet port formed in a forward end of the housing, the inlet port configured to receive at least one of air, an air-fuel mixture, and the high pressure boost air; wherein the housing defines a seal receiving bore defined between a rotor cavity and a bearing cavity, the high pressure rotor seal disposed in the seal receiving bore; wherein the primary lip extends toward an air side of the supercharger; wherein the primary lip is curved and extend towards a bearing cavity of the supercharger; wherein the rigid guide plate comprises a generally annular rim, a first flange, and a second flange; wherein the first flange extends radially outward from the rim, and the second flange extends radially inward from the rim; wherein the second flange is curved and generally follows a curvature of the primary lip; wherein a gap is defined between an end of the second flange and the rotor shaft, the gap configured to allow the lubrication to flow to the primary lip; and a rigid cage disposed at least partially within the body, wherein the primary lip includes hydrodynamic grooves formed on a first side of the primary lip, the hydrodynamic grooves configured to pump oil across the rotor seal, and wherein the rigid guide plate is pressed into an inner diameter of the body.

DETAILED DESCRIPTION

With initial reference toFIG. 1, a schematic illustration of an exemplary combined turbocharger and supercharger boost system10is shown. The combined boost system10generally includes an engine12, a turbocharger14, and a supercharger16.

In the illustrated example, the engine12can include a plurality of cylinders18, and an intake manifold assembly20and exhaust manifold assembly22for respectively directing combustion air to and from an engine combustion chamber (not shown).

The turbocharger14and the supercharger16can be positioned in series along an air intake24of the engine12with the supercharger16positioned downstream of the turbocharger14. The turbocharger14generally includes a compressor portion26and a turbine portion28, which can be mechanically coupled to, and operable to drive, the compressor26. The turbine portion28can be disposed in an exhaust gas conduit30, which can receive exhaust gas from the engine12through the exhaust manifold assembly22. The compressor portion26can receive air through an intake conduit32having an air filter34. The compressor portion26can compress the intake air and subsequently supply the compressed intake air to an intercooler36before it is directed to the supercharger16.

The supercharger16can include an inlet port38which can receive air or air-fuel mixture from an inlet duct or passage40, and can further include a discharge or outlet port42, directing the charged air to the intake valves (not shown) via a discharge duct44. In other embodiments, the supercharger16can include a front inlet design such that the inlet port is located at a forward end of the supercharger housing (e.g., opposite illustrated inlet port38) proximate a gear case or isolator assembly or both.

The inlet duct40and discharge duct44can be interconnected by means of a bypass passage46. If the engine12is of the Otto cycle type, a throttle valve48can control air or air-fuel mixture flowing into the inlet duct40from a source, such as ambient or atmospheric air, in a well know manner. Alternatively, the throttle valve48may be disposed downstream of the supercharger16.

A bypass valve50can be disposed within the bypass passage46and may be moved between an open position and a closed position by an actuator assembly (not shown) or the like. The actuator assembly can be operative to control the supercharging pressure in the discharge duct44as a function of engine power demand. When the bypass valve50is in the fully open position, air pressure in the inlet duct40is relatively low, but when the bypass valve50is fully closed, the air pressure in the inlet duct40is relatively high. The bypass valve50shown and described herein is exemplary and other configurations are contemplated. In this regard, a modular (integral) bypass, an electronically operated bypass, or no bypass may be used.

With reference toFIG. 2, additional features of the supercharger16will be described in greater detail. The supercharger16includes a housing78with a rotor assembly80having intermeshed rotors82,84, which transport the incoming compressed air from the supercharger inlet38to a supercharger outlet42. The rotors82,84are respectively coupled to the rotor shafts88,90for rotation therewith, and timing gears92,94are provided for transferring torque between the rotors82,84and for ensuring that the rotors82,84rotate at the same speed and do not interfere with one another. The rotor shaft88is mechanically coupled to a drive system such as the engine12(e.g., from the engine crankshaft), an electric motor/generator (not shown), or a combination thereof (e.g., hybrid system) to transfer torque to drive the intermeshed rotors82,84for boosting the pressure of the air being supplied to the engine12.

As illustrated inFIG. 2, the supercharger housing78defines a rotor case96and a gear case98separated by a wall100. The rotor case96houses the rotors82,84and at least partially defines a rotor cavity102for directing air between the supercharger inlet38and the outlet42. The gear case98houses the timing gears92,94and the shaft bearings108,110, and at least partially defines a bearing cavity104to retain lubricating oil for the timing gears92,94, the shaft bearings108,110, or other components. The first and second rotor shafts88and90are rotatably supported by the housing78at the first bearing108and the second bearing110.

A coupling or isolator assembly112couples an input shaft114to the first rotor shaft88. In one example, a first hub116couples the input shaft114to the isolator assembly112on a first end118, and a second hub120couples the first rotor shaft88to the isolator assembly112on an opposite end122. The timing gear92may be mounted on a forward end of the rotor shaft88and defines teeth (not shown) that are in meshed engagement with gear teeth (not shown) of the second timing gear106that may be mounted on the second rotor shaft90. It will be appreciated in light of the disclosure that the isolator assembly112shown inFIG. 3is exemplary and other isolators may be used to couple the input shaft114and the first rotor shaft102.

In one configuration, positive torque is transmitted from the internal combustion engine12to the input shaft114by any suitable drive mechanisms, such as a belt and pulley drive system (not shown). Torque can be transmitted from the input shaft114to the rotor shaft assembly80through the isolator assembly112, which provides torsional and axial damping and may further account for minor misalignment between the input shaft114and the first rotor shaft88. When the engine12is driving the timing gears92,94and the rotors82,84, such is considered to be transmission of positive torque. On the other hand, whenever the momentum of the rotors82,84overruns the input from the input shaft114, such is considered to be the transmission of negative torque.

In the illustrated example, the housing78further includes seal receiving cavities or bores124, which are positioned intermediate the rotor cavity102and the bearing cavity104. The seal receiving bores124are configured to receive rotor shaft seals200,300,400to fluidly separate and isolate the rotor cavity102and the bearing cavity104. The high pressure rotor shaft seals200,300,400are disposed about the rotor shafts88,90and are configured to seal the gear case98and can be shown to prevent pressurization of the bearing cavity104by the high pressure boost air supplied to the rotor cavity102from the turbocharger14.

As illustrated inFIGS. 3-6, the high pressure rotor seals200generally include a cage202, a primary, oil side lip204, and one or more boost pressure blocking lips206. The cage202can be fabricated from a rigid material (e.g., metal or plastic) and can include opposed first and second flanges208and210configured to secure the primary lip204and the boost pressure blocking lips206therebetween. Oil side lip204or blocking lips206or both may be fabricated from a flexible material such as PTFE. As illustrated inFIG. 6, a plurality of spacers212can be disposed between the primary lip204, the boost pressure blocking lips206, and the cage202. One or more spacers212can be sized and configured to provide predefined spacing between adjacent lips204,206, between an adjacent lip204and flange208,210, or between an adjacent lip206and flange208,210.

In the present example, the primary lip204includes a proximal portion214, a distal portion216, a first side218, and an opposite second side220. The proximal portion214is disposed at least partially within the cage202between a pair of spacers212. The distal portion216can extend outwardly from the proximal portion214, and thus the cage202, toward the rotor shaft88or90. As illustrated inFIGS. 5 and 6, the distal portion216subsequently curves and extends toward the bearing cavity104of the supercharger16. As shown, the distal portion216is curved along at least a portion and has a radius of curvature that may be determined by a desired primary lip thickness and desired hoop stress.

At least a portion of the distal portion first side218can contact and be in sealing arrangement with an outer surface222of the rotor shaft88or90(seeFIG. 6). In the illustrated example, the distal portion first side218includes a plurality of hydrodynamic grooves224configured to pump oil across the seal200, which can be shown to facilitate cooling the shaft/seal interface and removing debris from the seal. As such, the primary lip204can extend toward the bearing cavity104and can be shown to prevent oil from traveling from the bearing cavity104to the rotor cavity102.

The boost pressure blocking lip206includes a proximal portion230, a distal portion232, a first side234, and a second side236. The proximal portion230can be disposed at least partially within the cage202between a pair of spacers212or between one spacer212and a portion of the cage202(e.g., flange210). The distal portion232can extend outwardly from the proximal portion230, and thus the cage202, toward the rotor shaft88or90. As illustrated inFIGS. 5 and 6, the distal portion232subsequently curves and extends toward the air side or the rotor cavity102of the supercharger16. As shown, the distal portion232can be curved along at least a portion and has a radius of curvature that can be based on a combination of a thickness and desired hoop stress of the primary lip204.

At least a portion of the distal portion first side234can contact and be in sealing arrangement with the rotor shaft outer surface222. The boost pressure blocking lip206can extend toward the rotor cavity102and can be shown to prevent turbocharger high pressure boost air from entering the bearing cavity104. As high pressure boost air from the turbocharger14enters the supercharger16, a portion of the high pressure boost air can contact the distal portion second side236or an end238of the lip206or both, that can force the distal portion first side234further against the rotor shaft88,90to maintain the seal therebetween. As shown inFIGS. 5 and 6, additional boost pressure blocking lips206may be disposed between the outermost blocking lip206and the primary lip204and can be shown to provide additional sealing or to function as a backup seal in the event of damage or wear to the outermost blocking lip206. Although three boost pressure blocking lips206are illustrated, the high pressure rotor seals200may have any suitable number of lips206that enable the seal200to function as described herein. For example, the seal200may include one or four lips206.

FIG. 7illustrates a rotor seal290that can be an alternative example of the seal200, except the seal290includes a backing plate300. In the illustrated example, the backing plate300can be fabricated from a rigid material (e.g., metal) and can include a proximal portion302, a distal portion304, a first side306, and a second side308. As shown, the proximal portion302can be disposed at least partially within the cage202between the primary lip204and blocking lip206. However, one or more spacers212may be used therebetween. The distal portion304can extend outwardly from the proximal portion302, and thus the cage202, toward the rotor shaft88or90. As illustrated inFIG. 7, the distal portion304subsequently curves and extends toward the bearing cavity104of the supercharger16. As shown, the distal portion304can be curved along at least a portion thereof. In one example, distal portion304can follow or generally follow the curvature of the primary lip204. The backing plate300can be configured to provide structural support to the primary lip204and can be shown to prevent the primary lip204from being crushed under excessive boost pressure.

Described herein are systems and structures for sealing configurations for boost systems, particularly when a supercharger is disposed downstream of a turbocharger and receives high boost pressure therefrom. The system includes high pressure rotor seals that include one or more boost pressure blocking lips. The boost pressure blocking lips are in sealing contact with a rotor shaft and are further forced against rotor shaft under high boost pressure conditions to maintain a seal therebetween. The high pressure rotor seals may include a backing plate configured to provide structural support to a primary, oil-side lip. As such, the high pressure rotor seals prevent crushing of the rotor seal under excessive boost pressure from an upstream boost system.

FIGS. 8-10illustrate another example high pressure rotor seal400that generally includes a cage402, a body404, a primary oil side lip406, and a support plate408. The cage402can be fabricated from a rigid material (e.g., metal or plastic), and the body404can be disposed about the cage402such as by overmolding. The body404can define an outer surface or410, a first inner surface440, and a second inner surface442. In one embodiment, the body404can be fabricated from an elastic material such as rubber, and the primary lip406can be fabricated from a flexible material such as PTFE. The support plate408can be fabricated from a rigid material (e.g., metal or plastic) and may be pressed into the seal400and/or the housing80, as described herein in more detail.

In the present example, the primary lip406can include a proximal portion414, a distal portion416, a first side418, and an opposite second side420. The proximal portion414can be clamped into position, for example, by the cage402or metal rings. The distal portion416can extend outwardly from the proximal portion414, and thus the cage402, toward the rotor shaft88or90. As illustrated inFIG. 10, the distal portion416subsequently curves and extends toward the air side or the rotor cavity102of the supercharger16.

At least a portion of the distal portion first side418can contact and be in sealing arrangement with an outer surface222of the rotor shaft88or90(seeFIG. 10). Although not shown, the distal portion first side418may include a plurality of hydrodynamic grooves configured to pump oil across the seal400, which facilitates cooling the shaft/seal interface and removing debris from the seal. As such, the primary lip406can extend toward the rotor cavity102and can be shown to prevent oil from traveling from the bearing cavity104to the rotor cavity102.

The support plate408can be generally annular and can include an annular or generally annular rim424, a first outwardly extending flange426, and a second inwardly extending flange428. The rim424can include a first end430and an opposite second end432. The flange426can be coupled to the rim first end430and extend radially outward of the rim424, and the flange428can be coupled to the rim second end432and extend radially inward of the rim424. The flange428may be shaped to substantially follow at least a portion of the shape of the primary lip406, and the flange428can be spaced apart from the rotor shaft outer surface222to define a gap therebetween that enables lubricating oil to flow to the primary lip406.

In one example, the support plate408can be inserted or pressed into a seal inner diameter412, and the high pressure rotor seal400can be subsequently inserted into the seal receiving bore124. In another example, the high pressure rotor seal400can be inserted into the seal receiving bore124and the support plate408can be subsequently inserted or pressed into the seal inner diameter412.

In the assembled position, as illustrated inFIGS. 3-5, the rim424can be disposed against or in proximity to the seal inner diameter412, the outwardly extending flange426can be disposed against or in proximity to a shoulder434of the housing80(seeFIG. 10), and the inwardly extending flange428can be disposed against or in proximity to the primary lip406. As such, the support plate408can be disposed at least partially within the seal body404to provide structural support to the seal400, and thus the primary lip406, to prevent the primary lip406or other portions of the seal400from being crushed under excessive boost pressure.

Described herein are systems and structures for sealing configurations for boost systems, particularly when a supercharger is disposed downstream of a turbocharger and receives high boost pressure therefrom. The system includes high pressure rotor seals and a rigid guide plate disposed within at least a portion of the high pressure rotor seal. The support plate is configured to provide structural support and increase radial rigidity of components of the seal such as the primary lip, which extends toward the air side of the supercharger. As such, the high pressure rotor seals prevent crushing of the rotor seal under excessive boost pressure from an upstream boost system.

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.