SIMPLIFIED ROOTS-TYPE BLOWER
The present disclosure relates to a simplified roots-type blower having an improved sound signature. The roots-type blower includes a rotor bore housing having a molded, one-piece polymeric construction. The rotor bore housing defines a first rotor bore and a second rotor bore. The rotor bore housing also defines a first bearing pocket corresponding to the first rotor bore and a bearing pocket corresponding to the second rotor bore axis. The rotor bore housing further defining a timing gear chamber.
This application is a Continuation of PCT/US2012/040736, filed 4 Jun. 2012, which claims benefit to U.S. Patent Application Serial No. 61/492,520 filed on 2 Jun. 2011 and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.
TECHNICAL FIELDThe present disclosure relates generally to blowers. More particularly, the present disclosure relates to blowers such as roots-type air blowers.
BACKGROUNDRoots-type air blowers are positive displacement pumps that move air through the use of intermeshing rotors. The rotors are mounted within rotor bores defined by a rotor bore housing. The rotors are typically supported within bearings mounted within a bearing plate assembly that attaches to the rotor bore housing. The bearings function to locate the rotors in the bearing plate and are press-fit into pockets machined in the bearing plate. A relatively high degree of precision is needed to ensure that no contact is made between the rotors or between the rotors and the rotor bore housing. Thus, the bearing plate assembly and the rotor bore housing are manufactured from metal using tightly controlled assembly and machining operations. In view of the above, there is a need for simplified roots-type blower designs that can be manufactured in a cost-effective manner while still being capable of efficient operation.
Another challenge for current roots-type blower designs relates to noise production. For example, current roots-type blower designs typically generate noise when high pressure air at the outlet in-rushes into the atmospheric air transported by the rotors. This air pulsation at the outlet is audible and can be amplified by the typical housing and bearing plate materials used to manufacture current roots-type blowers. Furthermore, audible timing gear rattle resulting from engine torque is also amplified by the current materials used to manufacture existing roots-type blowers. Therefore, improvements in the area of noise dampening are also needed.
SUMMARYOne aspect of the present disclosure relates to a simplified roots-type blower having a molded polymeric rotor bore housing with integrally molded bearing pockets. This type of design eliminates the need for machining.
Another aspect of the present disclosure relates to a roots-type blower having a molded, polymeric rotor bore housing and rotors designed with sharp edges which cut the housing to an exact size during the run-in period at start up thereby improving volumetric and thermal efficiency. As the rotors are rotated during the initial run-in period, the peripheral edges of the rotors cut away portions of the housing defining the rotor bores such that the inner shapes of the rotor bores match the outer shape defined by the peripheral edges of the rotors as the rotors are rotated about their respective axes. In certain embodiments, at least portions of the rotor bores are intentionally molded slightly undersized to allow the undersized portions of the rotor bores to be cut away by the rotors during the initial run-in period at startup.
A further aspect of the present disclosure relates to a roots-type blower molded or otherwise constructed of a polymeric (e.g., plastic) material having dampening properties that assist in reducing timing gear rattle and limiting the amplification of air pulsation related noise. In one embodiment, the use of dampening plastic materials combined with a design having bearing pockets and rotor bores integrated into the same housing piece can reduce the pulsation noise and gear rattle typical of conventional roots-type blowers. In certain embodiments, the use of plastic timing gears or the combination of metal (e.g., steel) and plastic timing gears can have a significant impact on reducing gear rattle.
A further aspect of the present disclosure relates to a roots-type blower having an injection molded, single-piece housing that includes rotor bores and bearing pockets integrated therein. In certain embodiments, bearings are molded within the bearing pockets using an insert molding technique. In certain embodiments, the polymeric material of the housing is reinforced with reinforcing members such as glass fibers. In certain embodiments, glass fibers are specifically oriented to enhance part precision and structural integrity. In certain embodiments, the molded, polymeric housing defining the rotor bores and the bearing pockets connects with an inlet housing having a metal construction. In certain embodiments, an alignment/pilot interface is provided between the metal, inlet housing and the molded, plastic rotor bore housing. The alignment interface can be configured to assist in improving or maintaining concentricity of the rotor bores.
Still another aspect of the present disclosure relates to a compact roots-type blower having rotor bearings mounted directly above an outlet of the roots-type blower. In one embodiment, the roots-type blower includes rotor bores, rotors rotationally mounted within the rotor bores, rotor timing gears mounted at one end of the roots-type blower and a rotor drive pulley mounted at an opposite end of the roots-type blower. In such an embodiment, the rotor bores are positioned between the drive pulley and the rotor timing gears. In certain embodiments, the inlet of the roots-type blower is positioned generally adjacent the second end of the roots-type blower and the outlet of the roots-type blower is positioned generally adjacent to the first end of the roots-type blower.
Still another aspect of the present disclosure relates to a roots-type blower including a rotor bore housing having a molded polymeric construction. The rotor bore housing defines a first rotor bore aligned along a first rotor bore axis and a second rotor bore aligned along a second rotor bore axis. The first and second rotor bore axes are parallel. The rotor bore housing also defines a first bearing pocket co-axially aligned with the first rotor bore axis and a second bearing pocket co-axially aligned with the second rotor bore axis. The rotor bore housing further defines a gear chamber. The roots-type blower also includes a first bearing mounted within the first bearing pocket and a second bearing mounted within a second bearing pocket. The roots-type blower further includes a first roots-type rotor having a first rotor shaft aligned along the first rotor bore axis and a second roots-type rotor having a second rotor shaft aligned along the second rotor bore axis. The first rotor shaft is supported by the first bearing such that the first roots-type rotor is free to rotate relative to the rotor bore housing about the first rotor bore axis. The second rotor shaft is supported by the second bearing such that the second roots-type rotor is free to rotate relative to the rotor bore housing about the second rotor bore axis. The roots-type blower further includes first and second gears positioned within the gear chamber. The first gear is coupled to the first rotor shaft and the second gear is coupled to the second rotor shaft. The first and second gears intermesh with one another and are configured for transferring torque between the first and second rotor shafts. In certain embodiments, the rotor bore housing defines an outlet of the roots-type blower, and the roots-type blower further includes a metal inlet housing that attaches to the rotor bore housing. The inlet housing defines an inlet of the roots-type blower.
Still another aspect of the present disclosure relates to a roots-type blower including a rotor bore housing having a fiber reinforced polymeric construction. The rotor bore housing defines a first rotor bore and a second rotor bore. The rotor bore housing also defines a first bearing pocket corresponding to the first rotor bore and a second bearing pocket corresponding to the second rotor bore. The rotor bore housing further defines a gear chamber. The roots-type blower also includes a first bearing mounted within the first bearing pocket and a second bearing mounted within the second bearing pocket. The roots-type blower further includes a first roots-type rotor having a first rotor shaft and a second roots-type rotor having a second rotor shaft. The first roots-type rotor is positioned within the first rotor bore and the second roots-type rotor is positioned within the second rotor bore. The first and second rotor shafts are rotatable about rotor shaft axes that are positioned such that the first and second root-type rotors intermesh as the first and second roots-type rotors rotate. The first rotor shaft is supported within the first bearing and the second rotor shaft is supported by the second bearing. The roots-type blower further includes first and second gears positioned within the gear chamber. The first gear is coupled to the first rotor shaft and the second gear is coupled to the second rotor shaft. The first and second gears intermesh with one another and are configured for transferring torque between the first and second rotor shafts. In certain embodiments, the roots-type blower can also include an inlet housing that attaches to the rotor bore housing. The inlet housing can have a metal construction and can define an inlet of the roots-type blower that is in fluid communication with the first and second rotor bores. The rotor bore housing can define an outlet of the roots-type blower that is in fluid communication with the first and second rotor bores.
A variety of additional aspects will be set forth in the description that follows. These aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad concepts upon which the embodiments disclosed herein are based.
The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the present disclosure. A brief description of the drawings is as follows:
The present disclosure relates generally to a roots-type blower having a simplified design adapted for providing an improved noise signature. For convenience and ease of explanation, various sides of the depicted embodiments have been designated as top, bottom, front and rear sides. It will be appreciated that such side designations are for convenience only and are not intended to limit how the device may be used. In this regard, it will be appreciated that embodiments in accordance with the principles of the present disclosure can be used in any orientation.
Referring to
The first roots-type rotor 76 is configured to rotate within the first rotor bore 88 and the second roots-type rotor 78 is configured to rotate within the second rotor bore 90. Intermeshing timing gears 96, 98 (see
Torque for rotating the first and second roots-type rotors 76, 78 can be provided by the drive pulley 70. For example, when the roots-type blower 50 is being used as a supercharger, the drive pulley 70 can be rotated by a belt driven by the crankshaft of the engine being supercharged. As shown at
The splined connection between the pulley 70 and the second rotor shaft 84 allows for relative sliding movement between the drive pulley 70 and the second rotor shaft 84. In this way, the connection can compensate of differences in thermal growth between the shaft 84 and the housing (e.g., the inlet housing and/or the rotor bore housing). Such compensation can help prevent excessive loading of the bearing 104 and/or the bearing 110. As shown at
The first and second roots-type rotors 76, 78 are supported for rotation relative to the inlet housing 60 and the rotor bore housing 64 by a relatively simple bearing configuration. For example, the first and second rotor shafts 80, 84 are supported adjacent there rearward ends by bearings 108, 110 (see
Referring to
Referring to
Referring to
One advantage of constructing the inlet housing 60 of metal is that the inlet housing 60 can be manufactured according to relatively precise tolerances. In certain embodiments, the inlet housing 60 is constructed of metal and includes a precisely tolerance (e.g., precision machined) piloting receptacle 140 that is sized to receive the axial projection 126 to provide the alignment interface 66 (see
As shown at
In certain embodiments, the rotor bore housing 64 can be molded with the first and second rotor bores 88, 90 slightly undersized. During assembly of the roots-type blower 50, the roots-type rotors 76, 78 are mounted within the rotor bores 88, 90. At initial startup, the roots-type rotors 76, 78 are rotated about their respective axes 82, 86. As this occurs, the cutting edges of the rotors 76, 78 cut away portions of the rotor bore housing 64 defining the rotor bores 88, 90. This type of cutting process ensures that the inner surfaces of the rotor bores 88, 90 have a shape that matches the shapes defined by the peripheral edges 204 of the roots-type rotors 76, 78 as the roots-type rotors 76, 78 are revolved about their respective axes 82, 86. In other words, the sharp edges of the rotors 76, 78 cut the plastic rotor bores to an exact diameter thereby reducing leakage and improving efficiency. This relatively exact sizing of the rotor bores 88, 90 ensures that air is inhibited from passing between the outer peripheries of the rotors 76, 78 and the wall of the rotor bore housing 64 along the cylindrical portions 92, 94. This assists in enhancing the volumetric and thermal efficiency of the device. To prevent air from leaking past the ends of the rotors and lowering efficiency during use of the blower, it is preferred for the shaft holes of the rotor housing to be sized (e.g., molded or shaped with inserts) to be in close proximity to the shafts of the rotors. In certain embodiments, the shaft holes are sized smaller than bases/roots of the projections/blades of the rotors 76, 78 on the rotor bore side.
In certain embodiments, the roots-type blower 50 is relatively small and is adapted for use as a supercharger for relatively small engines. For example, in one embodiment, the rotor bores 88, 90 define a combined volume equal to or less than 250 cubic centimeters and the roots-type blower 50 is adapted for use as a supercharger with an engine having a volume of less than one liter, or in the range of 0.6-1.0 liters. Of course, aspects of the present disclosure are applicable to larger sized blowers as well.
As indicated above, it is desirable for the design to be configured for inhibiting leakage between the roots-type rotors 76, 78 and the cylindrical portions 92, 94 of the rotor bore housing 64. In this regard, it is preferred to use a molding process in which the rotor bores 88, 90 are provided with a draft angle less than 2 degrees, or more preferably less than 1 degree, or even more preferably equal to 0.
In certain embodiments, it is desirable to avoid the use of fasteners. For example, various components can be connected together through the use of adhesive such as a ultraviolet light curable adhesive. In one embodiment, the rotor bore housing 64 is connected to the inlet housing 60 by an adhesive such as an ultraviolet light curable adhesive. It will be appreciated that while the blower inlet 62 is defined by a metal part in the form of an inlet housing 60, the bearings 108, 110, the timing gears 96, 98 and a majority of each of the roots-type rotors 76, 80 are provided within the rotor bore housing 64 which is preferably polymeric (e.g., plastic). Similarly, the blower outlet 68 is provided on the polymeric rotor bore housing 64. It will be appreciated that the polymeric construction of the rotor bore housing 64 has improved sound deadening and vibration dampening characteristics as compared to metal. Thus, the use of the polymeric rotor bore housing 64 can assist in dampening noise created by air rushing through the blower outlet 68 and can also assist in dampening or otherwise inhibiting noise associated with gear rattling.
In certain embodiments (see
Prior to injection molding the rotor bore housing 64, the metal shields 300 are pressed onto the bearings 108, 110 to prevent plastic from flowing into and contaminating the bearings 108, 110 during the injection molding process. As shown at
As indicated above, the rotor bore housing 64 preferably has a polymeric construction. In certain embodiments, reinforcing fibers (e.g., aramid fibers, glass fibers, carbon fibers, etc.) can be embedded in the polymeric base material forming the rotor bore housing 64. Shown at
From the forgoing detailed description, it will be evident that modifications and variations can be made without departing from the spirit and scope of the disclosure.
Claims
1. A roots-type blower comprising:
- rotor bore housing having a molded, one-piece polymeric construction, the rotor bore housing defining a first rotor bore and a second rotor bore, the rotor bore housing also defining a first bearing pocket corresponding to the first rotor bore and a bearing pocket corresponding to the second rotor bore axis, the rotor bore housing further defining a gear chamber;
- a first bearing mounted within the first bearing pocket and a second bearing mounted within the second bearing pocket;
- a first roots-type rotor having a first rotor shaft aligned along a first rotor axis and a second roots-type rotor having a second rotor shaft aligned along a second rotor bore axis, the first and second roots-type rotors being respectively positioned within the first and second rotor bores, the first and second roots-type rotors being rotatable relative to the rotor bore housing about their respective first and second rotor axes, the first and second rotor bore axes being relatively positioned such that the first and second roots-type rotors intermesh with one another when the first and second roots-type rotors are rotated about their respective first and second rotor axes, the first rotor shaft being supported by the first bearing and the second rotor shaft being supported by the second bearing; and
- first and second gears positioned within the gear chamber, the first gear being coupled to the first rotor shaft and the second gear being coupled to the second rotor shaft, the first and second gears intermeshing with one another and being configured for transferring torque between the first and second rotor shafts.
2. The roots-type blower of claim 1, wherein the first and second rotor bores each have a draft angle less than 2 degrees.
3. The roots-type blower of claim 1, wherein the first and second rotor bores each have a draft angle equal to zero.
4. The roots-type blower of claim 1, wherein the molded polymeric construction includes a polymeric base material and reinforcing fibers embedded within the base material.
5. The roots-type blower of claim 4, wherein the rotor bore housing includes first and second cylindrical pocket-defining walls that respectively define the first and second bearing pockets, and wherein the reinforcing fibers are aligned in a circumferential orientation within each of the first and second cylindrical pocket defining walls.
6. The roots-type blower of claim 5, wherein the rotor bore housing includes first and second rotor bore-defining walls that respectively define the first and second rotor bores, and wherein the reinforcing fibers within the first and second rotor bore-defining walls are oriented parallel with respect to the first and second rotor bore axes.
7. The roots-type blower of claim 1, wherein the first and second rotor bores have a combined volume less than 250 cubic centimeters.
8. The roots-type blower of claim 1, wherein the rotor bore housing defines an outlet in fluid communication with the first and second rotor bores, and wherein the outlet and the first and second bearings are relatively positioned such that a reference plane perpendicular to the first and second rotor bore axes intersects the outlet and the first and second bearings.
9. The roots-type blower of claim 1, wherein the first and second bearings are insert-molded into their respective first and second bearing pockets.
10. The roots-type blower of claim 9, further comprising a first bearing shield surrounding the first bearing and a second bearing shield surrounding the second bearing, the first and second bearing shields being configured to prevent plastic from contaminating the first and second bearings when the first and second bearings molded within the rotor bore housing.
11. The roots-type blower of claim 1, wherein the first and second rotors have cutting edges that cut the rotor bore housing during an initial run-in period to shape the first and second rotor bores.
12. The roots-type blower of claims 1, wherein the rotor bore housing has first and second opposite ends spaced-apart from one another along the first and second rotor bore axes, wherein the gear chamber is positioned adjacent the first end, wherein the first bearing is positioned between the first rotor bore and the first gear, wherein the second bearing is positioned between the second rotor bore and the second gear, wherein the rotor bore housing defines an outlet between the first sand second ends, wherein the roots-type blower also includes an inlet housing that mounts to the second end of the rotor bore housing, the inlet housing defining an inlet in fluid communication with the first and second rotor bores.
13. The roots-type blower of claim 12, wherein the inlet housing defines a third bearing pocket co-axially aligned with the first rotor axis, wherein the inlet housing defines a bearing mounting stub co-axially aligned with the second rotor axis, wherein the roots-type blower includes third and fourth bearings, wherein the third bearing supports the first rotor shaft and is mounted within the third bearing pocket, wherein the fourth bearing supports the second rotor shaft and is mounted on the bearing mounting stub, and wherein the roots-type blower further includes a pulley mounted on the fourth bearing and coupled to the second rotor shaft by a splined connection.
14. The roots-type blower of claim 12, wherein the inlet housing is metal.
15. The roots-type blower of claim 14, wherein the rotor bore housing and the inlet housing interconnect at an alignment interface, and wherein the alignment interface is configured such that the inlet housing enhances concentricity of the first and second rotor bore about their respective first and second rotor axes.
16. The roots-type blower of claim 15, wherein the alignment interface includes a axial projection at the second end of the rotor bore housing that is received within an alignment receptacle defined by the inlet housing.
17. The roots-type blower of claim 16, wherein the axial projection and the alignment receptacle include first curved portions that extend about the first rotor axis and second curved portions that extend about the second rotor axis.
18. The roots-type blower of claim 17, further comprising a plurality of axial ribs provided on an exterior of the axial projection.
19. A method for making a roots-type blower having rotors mounted within rotor bores defined by a polymeric rotor housing, the rotors being rotatable about rotor axes, the method comprising:
- injection molding the polymeric rotor housing;
- mounting the rotors within the rotor bores; and
- defining a final interior shape of the rotor bores by cutting away portions the polymeric rotor housing with the rotors as the rotors are rotated about their respective axes.
20. A roots-type blower comprising:
- rotor bore housing having a fiber reinforced polymeric construction, the rotor bore housing defining a first rotor bore and a second rotor bore, the rotor bore housing also defining a first bearing pocket corresponding to the first rotor bore and a second bearing pocket corresponding to the second rotor bore, the rotor bore housing further defining a gear chamber and a blower outlet, the blower outlet being in fluid communication with the first and second rotor bores;
- a first bearing mounted within the first bearing pocket and a second bearing mounted within the second bearing pocket;
- a first roots-type rotor having a first rotor shaft aligned along a first rotor axis and a second roots-type rotor having a second rotor shaft aligned along a second rotor bore axis, the first and second roots-type rotors being respectively positioned within the first and second rotor bores, the first and second roots-type rotors being rotatable relative to the rotor bore housing about their respective first and second rotor axes, the first and second rotor bore axes being relatively positioned such that the first and second roots-type rotors intermesh with one another when the first and second roots-type rotors are rotated about their respective first and second rotor axes, the first rotor shaft being supported by the first bearing and the second rotor shaft being supported by the second bearing; and
- first and second gears positioned within the gear chamber, the first gear being coupled to the first rotor shaft and the second gear being coupled to the second rotor shaft, the first and second gears intermeshing with one another and being configured for transferring torque between the first and second rotor shafts.
21. The roots-type blower of claim 20, further comprising an inlet housing that attaches to the rotor bore housing, the inlet housing having a metal construction, wherein the inlet housing defines an inlet of the roots-type blower that is in fluid communication with the first and second rotor bores.
22. The roots-type blower of claim 21, further comprising a pulley coupled to the second rotor shaft and rotatably mounted on the inlet housing, and wherein the inlet housing is connected to a first end of the rotor bore housing and the gear chamber is positioned at an opposite second end of the rotor bore housing.
23. The roots-type blower of claim 22, wherein the inlet is positioned at a top side of the roots-type blower and the outlet is positioned at a bottom side of the roots-type blower, and wherein at least a portion of the outlet is positioned directly beneath the first and second bearing pockets.
Type: Application
Filed: Dec 2, 2013
Publication Date: Apr 10, 2014
Inventors: William Nicholas EYBERGEN (Harrison Twp., MI), Kelly Ann WILLIAMS (South Lyon, MI)
Application Number: 14/094,044
International Classification: F04C 29/06 (20060101); F04C 2/12 (20060101);