WO2019079555A1

WO2019079555A1 - Supercharger bearing plate outlet profile

Info

Publication number: WO2019079555A1
Application number: PCT/US2018/056449
Authority: WO
Inventors: Justin Keiffer; Eric Locker
Original assignee: Eaton Intelligent Power Limited
Priority date: 2017-10-19
Filing date: 2018-10-18
Publication date: 2019-04-25

Abstract

A supercharger constructed in accordance to one example of the present disclosure includes a housing a first rotor, a second rotor and a bearing plate. The first rotor and the second rotor are received in cylindrical overlapping chambers of the housing. The first rotor is supported by a first rotor shaft. The second rotor is supported by a second rotor shaft. The first rotor has a first rotor lobe profile. The second rotor lobe has a second rotor lobe profile. The bearing plate is coupled to the housing and having an oil cavity side and an air cavity side. The bearing plate has first and second outer walls that define an outer boundary of an inset portion. The first and second outer walls have respective outer wall profiles that substantially match the first and second lobe profiles.

Description

SUPERCHARGER BEARING PLATE OUTLET PROFILE

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 62/574,438, filed October 19, 2017, the contents of which is incorporated herein by reference thereto.

FIELD

[0002] The present disclosure relates generally to superchargers and more particularly to a bearing plate for a supercharger.

BACKGROUND

[0003] 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, can be driven by meshed timing gears. 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 many examples a supercharger can operate in high temperature environments. It is desirable to maintain the components of the supercharger in satisfactory operating condition to withstand significant temperature fluctuations.

[0004] 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

[0005] A supercharger constructed in accordance to one example of the present disclosure includes a housing a first rotor, a second rotor and a bearing plate. The first rotor and the second rotor are received in cylindrical overlapping chambers of the housing. The first rotor is supported by a first rotor shaft. The second rotor is supported by a second rotor shaft. The first rotor has a first rotor lobe profile. The second rotor lobe has a second rotor lobe profile. The bearing plate is coupled to the housing and having an oil cavity side and an air cavity side. The bearing plate has first and second outer walls that define an outer boundary of an inset portion. The first and second outer walls have respective outer wall profiles that substantially match the first and second lobe profiles.

[0006] According to additional features, both of the outer walls each further include a convex portion and a concave portion. The respective convex portions on the outer walls are complementary to concave portions on the respective first and second rotors. The respective concave portions on the outer walls are complementary to convex portions on the respective first and second rotors. The air cavity side defines the inset portion that leads to an outlet port of the supercharger.

[0007] In other features, the inset portion has pressure relief slots formed thereon corresponding to each rotor and configured to minimize pressure and heat to improve isentropic efficiency of the supercharger. The pressure relief slots each include a pair of arcuate wall sections that converge into each other at a valley and are configured to receive a radial component of air movement at the inset portion. The bearing plate further includes a connecting wall that connects the respective valleys. The pressure relief slots each further include a forward convex wall portion configured to receive an axial component of air movement at the inset portion. The housing can define an outlet. An entirety of a transfer volume of air opens to the outlet substantially uniformly.

[0008] A supercharger constructed in accordance to another example of the present disclosure comprises a housing, a first rotor, a second rotor and a bearing plate. The first and the second rotor are received in cylindrical overlapping chambers of the housing. The first rotor is supported by a first rotor shaft and has a first rotor lobe profile that includes a first concave portion and a first convex portion. The bearing plate can be coupled to the housing and has an oil cavity side and an air cavity side. The bearing plate has a first outer wall having a first convex portion and a first concave portion. The first convex portion of the first outer wall is substantially complementary to the first concave portion of the first rotor lobe profile. The first concave portion of the first outer wall is substantially complementary to the first convex portion of the first rotor lobe profile.

[0009] According to additional features, the second rotor is supported by a second rotor shaft and has a second rotor lobe profile that includes a second concave portion and a second convex portion. The second outer wall has a second convex portion and a second concave portion. The second convex portion of the second outer wall is substantially complementary to the second concave portion of the second rotor lobe profile. The second concave portion of the second outer wall is substantially complementary to the second convex portion of the second rotor lobe profile.

[0010] In other features, the air cavity side defines an inset portion that leads to an outlet port of the supercharger. The inset portion has pressure relief slots formed thereon corresponding to each rotor and configured to minimize pressure and heat to improve isentropic efficiency of the supercharger. The pressure relief slots each include a pair of arcuate wall sections that converge into each other at a valley and are configured to receive a radial component of air movement at the inset portion. The bearing plate can further include a connecting wall that connects the respective valleys. The pressure relief slots each further include a forward convex wall portion that is configured to receive an axial component of air movement at the inset portion. The housing can define an outlet. An entirety of a transfer volume of air opens to the outlet substantially uniformly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0012] FIG. 1 is a schematic illustration of an intake manifold assembly having a positive displacement blower or supercharger constructed in accordance to one example of the present disclosure;

[0013] FIG. 2 is a cross-sectional perspective view of a supercharger constructed in accordance to one example of the present disclosure; [0014] FIG. 3 is a plan view of a bearing plate constructed in accordance to one example of the present disclosure;

[0015] FIG. 4 is a perspective view of the bearing plate of FIG. 3;

[0016] FIG. 5 is a perspective view of the bearing plate of FIG. 4 and shown with a pair of rotors; and

[0017] FIG. 6 is a plan view of the bearing plate and pair of rotors shown in FIG. 5.

DETAILED DESCRIPTION

[0018] With initial reference to FIG. 1 , a schematic illustration of an exemplary intake manifold assembly, including a Roots blower supercharger and bypass valve arrangement is shown. An engine 10 can include a plurality of cylinders 12, and a reciprocating piston 14 disposed within each cylinder and defining an expandable combustion chamber 16. The engine 10 can include intake and exhaust manifold assemblies 18 and 20, respectively, for directing combustion air to and from the combustion chamber 16, by way of intake and exhaust valves 22 and 24, respectively.

[0019] The intake manifold assembly 18 can include a positive displacement rotary blower 26, or supercharger of the Roots type. Further description of the rotary blower 26 may be found in commonly owned U.S. Pat. Nos, 5,078,583 and 5,893,355, which are expressly incorporated herein by reference. The blower 26 includes a housing 27 and a pair of rotors 28 and 29, each of which includes a plurality of meshed lobes. The rotors 28 and 29 are disposed in the housing 27 in a pair of parallel, transversely overlapping cylindrical chambers 28c and 29c, respectively. The rotors 28 and 29 may 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 rotors 28 and 29 at a fixed ratio, relative to crankshaft speed, such that the displacement of the blower 26 is greater than the engine displacement, thereby boosting or supercharging the air flowing to the combustion chambers 16.

[0020] The supercharger 26 can include an inlet port 30 which receives air or air-fuel mixture from an inlet duct or passage 32, and further includes a discharge or outlet port 34, directing the charged air to the intake valves 22 by means of a duct 36. The inlet duct 32 and the discharge duct 36 are interconnected by means of a bypass passage, shown schematically at reference 38. If the engine 10 is of the Otto cycle type, a throttle valve 40 can control air or air-fuel mixture flowing into the intake duct 32 from a source, such as ambient or atmospheric air, in a well know manner. Alternatively, the throttle valve 40 may be disposed downstream of the supercharger 26.

[0021] A bypass valve 42 is disposed within the bypass passage 38. The bypass valve 42 can be moved between an open position and a closed position by means of an actuator assembly 44. The actuator assembly 44 can be responsive to fluid pressure in the inlet duct 32 by a vacuum line 46. The actuator assembly 44 is operative to control the supercharging pressure in the discharge duct 36 as a function of engine power demand. When the bypass valve 42 is in the fully open position, air pressure in the duct 36 is relatively low, but when the bypass valve 42 is fully closed, the air pressure in the duct 36 is relatively high. Typically, the actuator assembly 44 controls the position of the bypass valve 42 by means of a suitable linkage. The bypass valve 42 shown 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.

[0022] With additional reference now to FIG. 2, the supercharger 26 can include an input shaft 50 supported by a first bearing 52 and a second bearing 54 and driven by a pulley 56. The pulley 56 may be configured to transmit torque from the engine crankshaft (not shown) to the input shaft 50. The input shaft 50 is coupled to a rotor shaft 60 that supports the rotor 28. A pair of timing gears 64 and 66 rotatably couple a rotor shaft 70 that supports the rotor 29 for concurrent, opposite rotation with the rotor shaft 60.

[0023] With particular reference now to FIGS. 2-5, additional features of the supercharger 26 will be described in greater detail. The supercharger 26 according to the present disclosure includes a bearing plate 100. The bearing plate 100 provides improved airflow and efficiency by matching a rotor profile on the outer portion of the bearing plate 100. An outlet cross-sectional area is increased while maintaining event timing. The outlet at the root of the rotor is improved making the relief slot port depth less sensitive.

[0024] The bearing plate 100 is formed of aluminum and includes an oil cavity side 102 (FIG. 3) and an air cavity side 104 (FIG. 4). The air cavity side 104 can define an inset portion 106 that leads to the outlet port 34 (FIG. 1 ). Pressure relief slots 110 (FIG. 3) can be formed at the inset portion 106 on the air cavity side 104. The pressure relief slots 1 10 each can generally include a pair of arcuate wall sections 1 12 and a forward convex wall portion 1 14. The arcuate wall sections 1 12 converge into each other at a valley 1 18 and are generally configured to receive a radial component of air movement at the inset portion 106. A connecting wall 1 19 connects the respective valleys 1 18.

[0025] The convex wall portions 114 are each configured to receive an axial component of air movement at the inset portion 106. The pressure relief slots 110 minimize unwanted pressure and heat and improve isentropic efficiency. In some examples, the meshing rotors 28 and 29 can form an air pocket that reduces in volume building a bubble of high pressure that can be detrimental to the efficiency of the supercharger 26. The pressure relief slots 1 10 are designed to relieve such high pressure and mitigate the potential detrimental impact. As a result, the pocket can remain open to the outlet port 34 versus creating an unwanted zone of high pressure. Heat and pressure buildup at the inset portion 106 is therefore minimized.

[0026] The bearing plate 100 further includes outer walls 120A and 120B that at least partially define an outer boundary 121 of the inset portion 106. As will become appreciated, and as best shown in FIGS. 5 and 6, the outer walls 120A and 120B are generally non-planar and configured to match a profile of a rotor lobe 124, 122 provided on a respective rotor 29, 28. Explained further referring to the lobe 124 of the rotor 29, the lobe 124 provides an outer lobe profile 128 (FIG. 5) that matches a complementary wall profile 130A of the outer wall 120A. Referring to FIG. 3, the wall profile 130A includes a convex portion 132A and a concave portion 134A to be complementary to a concave portion 142 and convex portion 144 (FIG. 6) of the rotor 29. It will be appreciated that the outer wall 120B includes a wall profile 130B similar to the outer wall 120A for substantially matching the profile of the rotor lobe 122 of the rotor 28. In this regard, the explanation will not be repeated herein with the understanding that like features of the bearing plate are denoted with a "B" suffix.

[0027] The outer walls 120A and 120B assist in relieving pressure and increase the exposed surface (outlet) area for the air to pass through the outlet portion 34. In this regard, any potential areas that the flow of air may tend to choke are reduced. Furthermore, the amount of airflow, resultant input power and/or thermal efficiency is improved over prior art outer wall designs that do not substantially match the rotor profile. By substantially matching the profile of the outer walls 120A, 120B with the respective rotor profiles of the rotor lobes 124, 122, the entirety of the transfer volume of air opens to the outlet 34 at the same time or uniformly.

[0028] With particular reference to FIGS. 3 and 4, additional features of the bearing plate 100 will be described. An outer plate flange 150 includes a bolt pattern 152 having a series of bolt holes 154. The location of the bolt pattern 152 on the outer plate flange 150 is optimized to reduce mass. In one non-limiting example the outer plate flange 150 has a first minimum overlapping flange width 156 and a second minimum overlapping flange width 158. The second minimum flange width 158 is defined at the bolt holes 154. The first width 156 can be at least 5 mm. The second width 158 can be at least 3 mm. Other dimensions are contemplated. As can be appreciated the widths 126 and 128 are configured to help minimize mass and packaging space.

[0029] 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.

Claims

CLAIMS What is claimed is:

1 . A supercharger comprising:

a housing;

a first rotor and a second rotor received in cylindrical overlapping chambers of the housing, the first rotor supported by a first rotor shaft, the second rotor supported by a second rotor shaft, the first rotor having a first rotor lobe profile, the second rotor lobe having a second rotor lobe profile; and

a bearing plate coupled to the housing and having an oil cavity side and an air cavity side, the bearing plate having first and second outer walls that define an outer boundary of an inset portion, the first and second outer walls having respective first and second outer wall profiles that substantially match the first and second lobe profiles.

2. The supercharger of claim 1 wherein both of the outer walls each further include a convex portion and a concave portion.

3. The supercharger of claim 2 wherein the respective convex portions on the outer walls are complementary to concave portions on the respective first and second rotors.

4. The supercharger of claim 3 wherein the respective concave portions on the outer walls are complementary to convex portions on the respective first and second rotors.

5. The supercharger of claim 1 wherein the air cavity side defines the inset portion that leads to an outlet port of the supercharger, the inset portion having pressure relief slots formed thereon corresponding to each rotor and configured to minimize pressure and heat to improve isentropic efficiency of the supercharger.

6. The supercharger of claim 5 wherein the pressure relief slots each include a pair of arcuate wall sections that converge into each other at a valley and are configured to receive a radial component of air movement at the inset portion.

7. The supercharger of claim 5 wherein the bearing plate further includes a connecting wall that connects the respective valleys.

8. The supercharger of claim 7 wherein the pressure relief slots each further include a forward convex wall portion configured to receive an axial component of air movement at the inset portion.

9. The supercharger of claim 1 wherein the housing defines an outlet and wherein an entirety of a transfer volume of air opens to the outlet substantially uniformly.

10. A supercharger comprising:

a housing;

a first rotor and a second rotor received in cylindrical overlapping chambers of the housing, the first rotor supported by a first rotor shaft and having a first rotor lobe profile that includes a first concave portion and a first convex portion; and

a bearing plate coupled to the housing and having an oil cavity side and an air cavity side, the bearing plate having a first outer wall having a first convex portion and a first concave portion, the first convex portion of the first outer wall being substantially complementary to the first concave portion of the first rotor lobe profile, the first concave portion of the first outer wall being substantially complementary to the first convex portion of the first rotor lobe profile.

1 1. The supercharger of claim 10 wherein the second rotor is supported by a second rotor shaft and having a second rotor lobe profile that includes a second concave portion and a second convex portion.

12. The supercharger of claim 1 1 wherein the second outer wall has a second convex portion and a second concave portion, wherein the second convex portion of the second outer wall is substantially complementary to the second concave portion of the second rotor lobe profile, and the second concave portion of the second outer wall is substantially complementary to the second convex portion of the second rotor lobe profile.

13. The supercharger of claim 10 wherein the air cavity side defines an inset portion that leads to an outlet port of the supercharger, the inset portion having pressure relief slots formed thereon corresponding to each rotor and configured to minimize pressure and heat to improve isentropic efficiency of the supercharger.

14. The supercharger of claim 13 wherein the pressure relief slots each include a pair of arcuate wall sections that converge into each other at a valley and are configured to receive a radial component of air movement at the inset portion.

15. The supercharger of claim 14 wherein the bearing plate further includes a connecting wall that connects the respective valleys.

16. The supercharger of claim 15 wherein the pressure relief slots each further include a forward convex wall portion configured to receive an axial component of air movement at the inset portion.

17. The supercharger of claim 10 wherein the housing defines an outlet and wherein an entirety of a transfer volume of air opens to the outlet substantially uniformly.