Supercharger Rotors for Increased Engine Power Output

This application is a continuation application, and claims the benefit of, U.S. patent application, entitled “Supercharger Rotors for Increase Engine Power Output,” filed on Dec. 21, 2022 and having application Ser. No. 18/069,687, the entirety of each of said application being incorporated herein by reference.

Embodiments of the present disclosure generally relate to superchargers for internal combustion engines. More specifically, embodiments of the disclosure relate to rotors for positive displacement superchargers that produce greater airflow and engine power output without negatively impacting overall airflow displacement.

In general, a supercharger increases the power output of an internal combustion engine. The supercharger increases the amount of air entering the internal combustion engine for combustion of fuel. Superchargers may be categorized as a form of forced induction that is mechanically powered, typically by a belt driven by a crankshaft of the engine. In particular, a positive displacement supercharger intakes air at atmospheric pressure and moves the air into an intake manifold of the engine at a higher pressure. Positive displacement superchargers are known to produce a flat torque curve throughout the engine's operating range and a lag-free throttle response.

One popular type of positive displacement supercharger is a Roots-type supercharger that includes a blower that pumps engine intake air by way of a pair of meshing rotor lobes that resemble a pair of stretched gears rotating within an enclosing case. A drawback to the Roots-type supercharger is that air flow tends to move in bursts, rather than smoothly and continuously as with, for example, a centrifugal supercharger compressor.

Over the years, positive displacement supercharger rotor packs have held to design criteria that keep tight tolerances between the rotors and an interior surface of the case as well as areas where the rotors interact with each other to maintain “best seal” where the rotors open, “induction event,” and close, “compression/displacement event,” creating an optimal pressure differential during opening/closing events. Due to adhering to these criteria, aerodynamic principles have not been applied to transition edges of the rotors in design and production processes. Testing has shown, however, that airflow losses in rotor cavity “fill” due to poor aerodynamic design is generally greater than losses between the rotors as well as losses between the rotors and the enclosing case. Given that engine manufacturers are always seeking ways to increase the power output of their engines while maintaining reliability and fuel efficiency, there is a continuous desire to improve the operation of positive displacement superchargers.

An apparatus and methods for a rotor pack are provided for a positive displacement supercharger that produces greater engine power output without loss of best seal between the rotors or between the rotors and an interior surface of an enclosing case. The rotors include relief zones and cupped portions at an intake airflow side of each lobe comprising the rotors. The relief zones allow additional airflow to enter the rotor pack while the cupped portions scoop additional airflow into the rotor pack during operation of the supercharger. Tapered radius portions of an enclosing case allow additional airflow to be dragged into the rotor pack. Pressure relief portions on a rotor bearing plate and angled portions on each lobe extend compression events during operation of the rotor pack. The angled portions reduce a margin of the lobes to sharpened edges without affecting the diameter of the margin.

In an exemplary embodiment, a rotor pack for a supercharger comprises: a first rotor and a second rotor that include meshed lobes; a shaft supporting each of the first rotor and the second rotor within an enclosing case; and a relief zone disposed at an intake airflow side of each lobe.

In another exemplary embodiment, the relief zone is configured to allow additional airflow to enter the rotor pack. In another exemplary embodiment, the relief zone comprises a curved surface that includes a line of curvature. In another exemplary embodiment, the line of curvature is tangent to a flat end face of the lobes and is tangent to a trailing surface of the lobe. In another exemplary embodiment, the relief zone extends from a termination of a radial blend prior to a compression zone to a termination of a radial seal of the lobe. In another exemplary embodiment, the compression zone comprises a valley that is disposed between adjacent pairs of lobes comprising each of the first rotor and the second rotor.

In another exemplary embodiment, the rotor pack further includes a cupped portion comprising an intake side of each of the first rotor and the second rotor. In another exemplary embodiment, the cupped portion comprises a triangular-shaped region disposed on a leading surface of each lobe. In another exemplary embodiment, the cupped portion comprises a sharpened leading edge that transitions into flattened region of each lobe. In another exemplary embodiment, the flattened region extends to a trailing surface of each lobe. In another exemplary embodiment, the sharped leading edge and the flattened region are configured to scoop additional airflow into a rotor cavity during operation of the first rotor and the second rotor.

In another exemplary embodiment, the cupped portion comprises a roughly 1.0 square inch area of the leading surface. In another exemplary embodiment, the cupped portion comprises a roughly 1.0-inch sharpened leading edge of the lobe. In another exemplary embodiment, the cupped portion includes a longitudinal distance of about 1.0 inch along a radial seal edge of the lobe.

In another exemplary embodiment, the rotor pack further includes an angled portion disposed on each lobe adjacent to a rotor bearing plate. In another exemplary embodiment, the angled portion is disposed between a trailing surface and a flat face of the lobe. In another exemplary embodiment, the angled portion reduces a margin of the lobe to a sharpened edge without affecting the overall diameter of the margin.

In another exemplary embodiment, the angled portion comprises a flat surface that is disposed at roughly 30-degrees relative to the flat face of the lobe. In another exemplary embodiment, the angled portion extends a longitudinal distance of approximately 0.500 inches into the trailing surface. In another exemplary embodiment, the angled portion extends a radial distance ranging up to 0.750 inches into the flat face of the lobe.

In another exemplary embodiment, the rotor pack further includes a pressure relief portion comprising a rotor bearing plate and configured to extend a compression event during operation of the rotor pack. In another exemplary embodiment, the pressure relief portion is configured to direct air out from between the first rotor and the second rotor in an efficient manner that minimizes turbulence. In another exemplary embodiment, the pressure relief portion is configured to relieve pressure from between the first rotor and the second rotor. In another exemplary embodiment, the pressure relief portion is configured to improve airflow away from the rotors pack during the compression event.

In another exemplary embodiment, the rotor pack further includes tapered radius portions comprising the enclosing case that are configured to allow additional airflow into between first rotor and the second rotor. In another exemplary embodiment, the tapered radius portion are configured to allow air that is dragged by the first rotor and the second rotor to enter between the first rotor and the second rotor.

These and other features of the concepts provided herein may be better understood with reference to the drawings, description, and appended claims.

While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The present disclosure should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the supercharger rotors and methods disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first rotor,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first rotor” is different than a “second rotor.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.

One popular type of positive displacement supercharger is a Roots-type supercharger that includes a blower that pumps engine intake air by way of a pair of meshing rotor lobes that resemble a pair of stretched gears rotating within an enclosing case. A drawback to the Roots-type supercharger is that air flow tends to move in bursts, rather than smoothly and continuously. In an attempt to “best seal” where the rotors open and close, aerodynamic principles have not been applied to transition edges of the rotors in design and production processes. Testing has shown, however, that airflow losses in rotor cavity “fill” due to poor aerodynamic design is generally greater than losses between the rotors as well as losses between the rotors and the enclosing case. Embodiments presented herein provide rotors for positive displacement superchargers that produce greater airflow and engine power output without negatively impacting overall airflow displacement.

illustrates a perspective view of an exemplary embodiment of a supercharger rotor pack, according to the present disclosure. The rotor packcomprises a first rotorand a second rotorthat include meshed lobesresembling a pair of twisted gears. The rotors,rotate in opposite directions such that the meshed lobespush intake air into an intake manifold of an internal combustion engine. As shown in, each pair of adjacent lobesis separated by an intervening valley. During rotation of the rotors,, each pair of meshed lobesand the intervening valleycomprise a cavity that moves away, or is displaced, from an intake airflow sideof the rotor packand opens into a compression side that leads to the intake manifold.

As shown in, the rotors,ride on shaftssuch that lobeson one rotor enter the valleyson the other rotor. In general, the shaftsare supported by bearings disposed in an enclosing case(see) such that the rotors,counterrotate within an interior cylindrical surfaceof the case. As shown in, the caseincludes intake portsconfigured to supply intake air to the rotors,. A compression portcomprising the caseprovides an exit for compressed air from the rotor packinto the intake manifold.

As shown in, the rotors,include flat end faces. The end facesabut interior surfaces of the caseso as to form a best seal that operates to prevent compressed air from migrating out of the intake manifold during rotation of the rotor pack. A relief zoneis disposed at the intake airflow side of each lobe. It is contemplated that the relief zonesallow additional airflow to enter between the meshed lobesrather than the airflow being abruptly severed by leading edgesof the lobesas the lobes become meshed.

illustrates a close-up view of an exemplary embodiment of a relief zonecomprising an intake side of the supercharger rotor packof, according to the present disclosure. In the illustrated embodiment, the relief zonecomprises a curved surface that includes a line of curvaturethat is tangent to the flat end faceas well as tangent to a trailing surfaceof the lobe. Further, the relief zoneextends from a pointto a point. Those skilled in the art will recognize that pointcomprises the termination of a radial blend prior to the valley(e.g., “compression zone”) while pointcomprises the termination of a radial seal of the rotor. Experimental observation has demonstrated that the relief zonesgive rise to substantially a 5% increase in engine power output. It should be borne in mind that the relief zonesmay be varied from the specific shape and size shown and described herein, without limitation, and without deviating beyond the spirit and scope of the present disclosure.

illustrate close-up views of an exemplary embodiment of a cupped portioncomprising an intake side of a supercharger rotor packin accordance with the present disclosure. The cupped portioncomprises a triangular-shaped region disposed on a leading surfaceof each of the lobescomprising the rotor pack. As shown in, the cupped portioncomprises a sharpened leading edgethat transitions into flattened regionof the lobes. In some embodiments, the flattened regionsmay extend to a trailing surface(see) of the lobe. The sharped leading edgeand the flattened regionare configured to scoop additional airflow into the rotor cavity during operation of the rotor pack. It is contemplated that sharpening the leading edgeand flattening regionof the leading surfacegives rise to greater airflow being moved by the rotor pack.

In one embodiment, the cupped portioncomprises a roughly 1.0 square inch area of the leading surface. In an embodiment illustrated in, the cupped portionincludes a radial distanceof about 1.0 inch along the lobe. As such, in the embodiment of, the lobeincludes a 1.0-inch sharpened leading edge. In an embodiment illustrated in, the cupped portionincludes a longitudinal distanceof about 1.0 inch along a radial seal edge of the lobe. It is contemplated that the distances,, as well as the degree of flattening of the regionmay be varied without limitation, and without straying beyond the spirit and scope of the present disclosure.

illustrates a close-up view of an exemplary embodiment of a rotor lobeincluding an angled portiondisposed adjacent to a rotor bearing plate, in accordance with the present disclosure. Those skilled in the art will recognize that the rotor bearing plategenerally includes gears configured to drive the counterrotating, meshed rotors, as described herein. As shown in, the angled portionis disposed between a trailing surfaceand a flat faceof the rotor lobe. More specifically, the angled portioncomprises a bevel that begins at a pointon the trailing surfaceand extends to a pointon a leading edge. The angled portionreduces a marginof the rotor lobeto a sharpened edgewithout affecting the overall diameter of the margin.

In some embodiments, the angled portioncomprises a flat surface that is disposed at roughly 30-degrees relative to the flat face. In some embodiments, the angled portionextends a longitudinal distance of approximately 0.500 inches into the trailing surface. Further, in some embodiments, the angled portionextends a radial distance ranging up to 0.750 inches into the flat face. It should be borne in mind that the specific distances as well as the angle of the angled portionmay be varied without deviating beyond the scope of the present disclosure.

With continuing reference to, an exemplary embodiment of a pressure relief portionof the rotor bearing plateis illustrated in accordance with the present disclosure. In general, the pressure relief portionis configured to extend the compression event during operation of the supercharger rotor pack. Conventional rotor bearing plates (e.g., bearing plates lacking the pressure relief portion) cover the cavity between the counterrotating rotors, such as the rotors,(see), before the compression event is completed. As such, the pressure relief portionis radiused and tapered so as to direct air out from between the rotors,and toward the discharge area in an efficient manner that minimizes turbulence. The pressure relief portionrelieves pressure from between the rotors,that would otherwise give rise to drag and reduced airflow. Experimental observation has demonstrated that the pressure relief portionaids in moving air away from the counterrotating rotors,during the compression event.

Turning, now, to, an exemplary embodiment of an enclosing casethat includes tapered radius portionsis shown in absence of the rotors,(see, for example,). The tapered radius portionsare configured to allow additional airflow into a cavity between the rotors,. As described herein, the rotors,include shaftsthat are supported by bearings disposed in the enclosing casesuch that the rotors,counterrotate within an interior cylindrical surfaceof the case. As shown in, the caseincludes intake portsthat supply intake air to the rotors,. While the rotors,turn, air is dragged in the direction of rotation of each rotor. The tapered radius portionsallow the air that is dragged by the rotors,to enter the cavity between the rotors instead of being sheared off by the lobespassing the sharp edges of the intake ports.

While the supercharger rotors and methods have been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the supercharger rotors are not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the supercharger rotors. Additionally, certain of the steps may be performed concurrently in a parallel process, when possible, as well as performed sequentially as described above. To the extent there are variations of the supercharger rotors, which are within the spirit of the disclosure or equivalent to the supercharger rotors found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.