Patent Application
20190113046
This disclosure relates to compressor wheels. More particularly, this disclosure pertains to compressor wheels that are composed in part of polymeric materials.
Compressors are used in applications such as turbochargers, superchargers and the like. Such devices typically include a compressor wheel that includes an array of aerodynamically contoured impeller blades that are supported on a central section. The central section, such as a hub section, is mounted on a rotatable drive shaft. In the case of a turbocharger, the rotatable shaft is driven by the turbine wheel. For turbochargers, the hub section generally includes a central axial bore into which the shaft extends and is fastened to the hub. Fastening can take any suitable form, such as the use of a threaded shaft and hub, a keyed hub or, alternately, a nose of the shaft may extend through the hub and be fastened thereto using a nut to tighten the hub against a shoulder or other diametrically enlarged structure rotatable with the shaft. The shaft rotatably drives the centrifugal compressor wheel in a direction such that the contoured blades draw in air axially and discharge that air radially outwardly at an elevated pressure level into a chamber of a compressor housing. The pressurized air is, then, supplied from the chamber to the air intake manifold of an internal combustion engine for admixture and combustion with fuel, all in a well-known manner.
Improvements in compressor technology have resulted in a variety of benefits including, but not limited to, increased compressor efficiencies, flow ranges and rapid transient response by careful design of the compressors, particularly the centrifugal compressor wheels. Polymeric centrifugal compressor wheels have been proposed in order to provide performance increases. In certain applications and configurations, it is believed that polymeric compressor wheels can provide high strength and low rotational inertia components. In certain applications, polymeric compressor wheels can be more readily configured into desired vane and fin shape associated with the blades. Unfortunately, the use of polymeric compounds for use in compressor wheels has been limited by some significant material and structural concerns. Polymeric compounds exhibit creep at compressor operating temperatures. This can compromise operational efficiency and limit the useful life of the associated compressor assembly and components such as the compressor wheel. Heretofore polymeric materials that could be employed in compressor wheels would exhibit structural distortion when employed in typical turbocharger operating conditions.
It is desirable to provide a compressor wheel configuration that can provide the efficiencies of polymeric structures without issues of creep and distortion.
A compressor wheel assembly that includes a metal tubular insert, a compressor wheel composed of a polymeric material, the compressor wheel member having an axially extending center portion molded on to the tubular insert and a shaft.
Also disclosed is a turbocharger that includes the compressor wheel assembly described herein.
The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.
Disclosed is a compressor wheel assembly that is configured to be used in devices such as turbochargers, superchargers and the like as well as a turbocharger, supercharger or the like that incorporates the compressor wheel as described herein. In certain embodiments, the compressor wheel as disclosed herein can provide a sturdy light weight mechanism.
As depicted in
As illustrated in
The shaft bore 22 is configured to telescopically receive shaft 24 therein as depicted in
The centrifugal compressor wheel member 16 of the centrifugal compressor wheel assembly 10 includes an axially extending center portion 26 that is molded on to the tubular insert 12. The centrifugal compressor wheel member 16 of the centrifugal compressor wheel assembly 10 includes a blade array 28 that is contiguously connected to the axially extending center portion 26 and extends radially outward therefrom. The blade array 28 includes a plurality of circumferentially-spaced, radially and axially extending, arcuate centrifugally disposed impeller blades 30. Any suitable number of impeller blades 30 may be utilized in blade array 28 depending on the design requirements of centrifugal compressor wheel member 16 of the centrifugal compressor wheel assembly 10. Impeller blades 30 may have any suitable circumferential spacing(s). Similarly, impeller blades 30 may extend radially and axially to any desired extent and have any suitable shape, particularly of the shape of the blade surfaces 27. The impeller blades 30 comprise airfoils, and the blade surfaces 27 may comprise airfoil surfaces. In certain embodiments, the shape of the impeller blades 30 may be described by a plurality of connected chords that project outwardly from the arcuate outer surface of the axially extending center portion 26 in a chordal direction 25. As used herein, a chord or chordal direction 25 is used to refer to a line segment joining two points of a curve and comprises the width of the impeller blades 30, or in the context of the impeller blades 30 as airfoils, a straight-line segment connecting the leading and trailing edges of an airfoil section. A direction generally transverse to chordal direction 25 may be defined as transchordal direction 29 and generally extends along the length of the impeller blades 30. In certain embodiments, the specific contouring of various impeller blades 30 may include a forward blade rake 32 generally adjacent to the inlet end 18 for at least some of the impeller blades 30, as illustrated in
The blade array 28 of the centrifugal compressor wheel member 16 of compressor wheel assembly 10 has an outer region 36 and an inner region 38. The blade array 28 of the centrifugal compressor wheel member 16 of the centrifugal compressor wheel assembly 10 can be formed of a suitable polymeric material. The polymeric material employed in the centrifugal compressor wheel member 16 of the centrifugal compressor wheel assembly 10 can be a thermoplastic or thermoset polymeric material suitable for use at elevated temperature and extended duty cycle. Non-limiting examples of such materials include epoxy compounds, phenolic polymers, polyimide polymers, polyamide polymers, polypropylene polymers or polyalkylarylketone polymers including but not limited to polyether ether ketone polymer.
Non-limiting examples of suitable epoxy resin compounds include those cross-linked with themselves as well as polyepoxides reacted with various polyfunctional hardeners to form thermosetting polymers. Suitable materials are formulated from epoxy resin prepolymers or higher molecular weight polymers that contain two or more epoxide groups. Non-limiting examples of suitable epoxy resins include bisphenol A which when reacted with epichlorhydrin yields diglycidyl ethers having the general formula:
in which n is an integer between 0 and 25. Other epoxy resins that can be employed include materials such as bisphenol F epoxy resin which undergoes epoxidation in a manner similar to bisphenol A as well as epoxy resins such as novolac epoxy resin, aliphatic epoxy resins formed by processes such as the glycidylaton of aliphatic alcohols or polyols to form monofunctional (e.g. dodecanol glycidyl ether), difunctional (butanediol diglycidyl ether), or higher functionality (e.g. trimethylolpropane triglycidyl ether) resins. Still other epoxy resins may include Glycidylamine epoxy resins such as those formed by the reaction of aromatic amines with epichlorhydrin; non-limiting examples of which include -p-aminophenol (functionality 3) and N, N′, N″, N′″-tetraglycidyl-bis-(4-aminophenyl)-methan (functionality 4).
The epoxy resin material can be cured by homopolymerization or by copolymerization with suitable polyfunctional curatives or hardeners including but not limited to include amines, acids, acid anhydrides, phenols, alcohols and thiols. Hardeners can be ambient or latent hardeners as desired or required.
Phenolic polymers as the term is used herein is defined as polymers based on various reaction products of phenols or substituted phenols with formaldehyde. Such material can be homopolymerized or can be polymerized with suitable co-polymerizable components and can be present as novolac resins or resol resins.
Polyimides suitable for use in the blade array 28 of the compressor wheel as disclosed herein can include materials produced by various methods such as reaction between a suitable dianhydride and a diamine or by reaction of a suitable dianhydride with a diisocyanate and can have the general formula:
In which R1 can be an aliphatic group, an aromatic group or a mixture of the two. In certain embodiments, non-limiting examples of suitable materials include materials such as poly-oxydiphenylene-pyromellitimide, commercially available under the trade designation “KAPTON” and believed to have the formula:
Suitable polyamide materials include aromatic, semi aromatic and aliphatic materials that are homopolymerized or copolymerized with suitable materials to provide or enhance desired properties, including temperature resistance and durability. Non-limiting examples of suitable aliphatic polyamides include Nylon 12, Nylon 11, Nylon 6, Nylon 6,6 and the like. Non-limiting examples of suitable semi-aromatic polyamides include polyphthalamides such as those having the general formula:
and is defined as such when 55% or more moles of the carboxylic acid portion of the repeating unit in the polymer chain is composed of a combination of terephthalic (TPA) and isophthalic (IPA) acids. Non-limiting examples of suitable polymers include PA 6T/66, PA 6T/DT and PA 6T/6I. It is also contemplated that the semi-aromatic polyamides can be blended or copolymerized with other polymeric materials.
It is also contemplated that suitable polyamide polymers can include materials such as the polyamide 46. Without being bound to any theory, it is believed that polyamide 46 can be a polymeric material having the general formula:
having a density of approximately 1.19 g/ml and a melting point of approximately 290° C. in certain applications.
Suitable polyether ether ketones have the general formula:
and can have an operating temperature above the operating temperature of the associated centrifugal compressor wheel assembly 10. In certain applications, the polyether ether ketone of choice will have stability at an operating temperature above about 140° C. with some grades having useful operating temperatures up to or above 250° C.
Where desired or required, the polymeric material may include a filler material such as a plurality of non-woven, discontinuous fibers as a dispersed reinforcing filler material to reinforce the polymer material. The polymeric material may include other suitable filler materials as an alternate or in addition to fiber reinforcement. Non-limiting examples of such material can include various organic and inorganic particulate filler materials. In certain embodiments, the filler material may comprise various nanoparticle filler materials, including carbon nanoparticles, such as various types of carbon nanotubes. Other non-limiting examples of suitable filler material can include at least one of metal fibers, glass fibers, metal particles, glass particles, carbon particles and the like. Polymer matrix composite material may include polymeric material and filler material in any suitable relative amounts while still providing a mixture that may be formed into the desired shape or shapes present in the blade array of centrifugal compressor wheel assembly 10. Filler material may be dispersed in polymeric material in any suitable manner, including as a homogeneous or heterogeneous dispersion.
Filler material may be formed from any suitable particulate and/or non-woven, discontinuous fiber material, including various metal, glass, polymer or carbon particles and/or fibers. Filler material may have any suitable characteristics including length, cross-sectional shape and cross-sectional size (e.g., fiber diameter for a cylindrical fiber), and may include a mixture of materials such as particles and non-woven fibers, of non-woven, discontinuous fibers having different characteristics and/or particles of differing sizes. The fibers that compose filler material may include individual filaments, tows or untwisted bundles of discontinuous (e.g., chopped) filaments or yarns.
The tubular insert 12 of the centrifugal compressor wheel assembly 10 can be formed of a suitable metal or metal alloy. The metal or metal alloy of choice be a composition capable of supporting the polymeric material of the centrifugal compressor wheel member 16 which may be over-molded on to the tubular insert 12 such that at least a portion of the tubular insert 12 is surrounded by and/or embedded in the polymeric material. Non-limiting examples of suitable metals materials include materials such as aluminum and aluminum alloys, magnesium and magnesium alloys, iron and iron alloys, copper and copper alloys, titanium and titanium alloys, steel and the like. In certain embodiments, the metal alloy can be a bronze or bronze alloys. In certain embodiments, the tubular insert 12 of the centrifugal compressor wheel assembly 10 can comprise at least one of the following: bronze, leaded bronze, copper iron, iron. leaded iron, aluminum, titanium, steel.
Non-limiting examples of bronze material include copper alloyed with suitable alloying metals. In certain embodiments, suitable bronze material is composed of copper is alloyed with between 10% and 14% tin. In certain embodiments, the suitable bronze material can also include zinc in addition to or instead of tin. Other bronze materials that can be employed in certain embodiments include but are not limited to phosphor bronze (0.5-11% tin 0.01-0.35% phosphorous, copper balance), aluminum bronze (4-11.5% aluminum, 0.5-6% iron, 0.8%-6% nickel, 0.5-2% manganese, 0.5% zinc, copper balance), silicon bronze (0-20% zinc, 0.5 to 6% silicon, copper balance).
Suitable stainless steels that can be employed in this disclosure include but are not limited to type 316L. Suitable copper iron alloys can contain copper, iron, and in some instances, beryllium. Non-limiting examples of copper iron alloys include those containing between 65% and 98% copper and between 35% and 2% iron.
The tubular insert 12 of the centrifugal compressor wheel assembly 10 is configured to connect to the centrifugal compressor wheel member 16. In the various embodiments depicted, the tubular insert 12 is in over-molded contact the polymeric material in the centrifugal compressor wheel member 16, and in particular is in contact with polymeric material present in the axially extending center portion 26. The polymeric material can be in over-molded contact with at least the outer circumferential surface 21 of the tubular insert 12. The tubular insert 12 can have one or more components that enhance connection and attachment between the polymeric material in the centrifugal compressor wheel member 16 and the tubular insert 12.
When in position in the compressor wheel member 16, the tubular insert 12 is positioned in the axial central region of the center portion 26 of the centrifugal compressor wheel member 16. In certain embodiments, the tubular insert 12 may have suitable cross-sectional profile elements that projects into the polymeric material present in the center portion 26 of the centrifugal compressor wheel member 16 of the centrifugal compressor wheel assembly 10 such that at least the outer circumferential surface 21 of the tubular insert 12 is encased in the associated polymeric material. In certain embodiments, the tubular insert 12 of the centrifugal compressor wheel assembly 10 can include at least one engagement member defined on, contiguously connected to and projecting outward from the outer circumferential surface 21 of the tubular insert 12. As depicted in
The tubular insert 12 can have any suitable number of engagement ridges 48 axially disposed about the outer circumferential surface 21. The engagement ridges 48 can be positioned around the periphery of the tubular insert 12 to provide rotational stability of the associated centrifugal compressor wheel assembly 10. The number of engagement ridges 48 will be that sufficient to enhance connection between the tubular insert 12 and polymeric material in the center portion 26 of the centrifugal compressor wheel member 16 during multiple duty cycles. The embodiments of the tubular insert 12 depicted in
In the embodiment depicted in
In certain embodiments, the engagement ridges 48 can extend along the entire length of the tubular insert and can have a suitable defined cross-sectional profile. Non-limiting examples include rounded U-shaped profiles, squared profiles and the like. Where desired or required, one or more of the engagement ridges 48 can have a cross sectional profile defining an outer surface 50 that is distal to the outer circumferential surface 21. The outer surface 50 can be planar or arcuate. In certain embodiments, the outer surface 50, when arcuate may have a degree of curvature that is equal to the curvature of the associated outer circumferential surface 21.
The one or more engagement ridges 48 can also each include side walls 52 that extend angularly outward from the associated outer circumferential surface 21 of the tubular insert 12 and terminate at the outer surface 50. The respective side walls 52 are positioned a spaced distance from one another such that the distance from side wall 52 to side wall 52 is less than the width of the associated outer surface 50. In certain embodiments, the side walls 52 can be planar. In the non-limiting embodiment depicted in
The centrifugal compressor wheel assembly 10 as disclosed herein can also include a suitable shaft 24 such as that depicted in
The shaft 24 can have any suitable cross-sectional configuration. In certain embodiments, it is contemplated that at least a portion of the shaft 24 located in the region corresponding to the tubular insert the can have a non-circular cross-sectional profile that corresponds to the cross-sectional profile of shaft bore 23 of tubular insert 12. Non-limiting examples of suitable cross-sectional profiles include hexagonal and flattened ellipsoid as illustrated in
An alternate embodiment of the centrifugal compressor wheel assembly 10 as disclosed herein is depicted in
Tubular insert 112 as depicted in
The tubular insert 112 is configured with a plurality of apertures 126 that extend through the wall member 119 and communicate with the shaft bore 122. In the embodiment depicted in
Where desired or required, the tubular insert 112 can also include outer adhesion members connected to and projecting from the outer circumferential surface 121 of wall member 119. In the embodiment depicted in
The tubular insert 112 may also include at least one end cap such as end caps 156, 158. End caps 156 and 158 are attached to the respective ends of the wall member 119 and can define an interior offset sufficient to maintain the shaft 24 a spaced distance from interior polymeric sleeve when the tubular insert 112 is in position in the body 15 and the centrifugal compressor wheel assembly 10 is on the use position.
The centrifugal compressor wheel member 16 can have any suitable configuration. In certain embodiments, the centrifugal compressor wheel member 16 includes a body 15 that can have one of more molded crevices 132 defined in the lower face of the centrifugal compressor wheel member 16 opposed to blade array 28 located axially around the center portion 26.
An alternate mold crevice configuration is depicted in
It is also contemplated that in certain embodiments, the centrifugal compressor wheel member 16 of centrifugal compressor wheel assembly 10 can be configured with a unitary crevice 142 extending around the center portion 26 that project outer at the centrally located position such as is depicted in
Tubular insert 212 is configured with a plurality of outwardly projecting arms 230 that are configured to be embedded in the centrifugal compressor wheel member 16. The outwardly projecting arms 230 can be configured with a plurality of apertures 232 to receive polymeric material therein. It is contemplated that polymeric material that composes the body 15 of the cylindrical shaft member 16 will surround the wall member 219 and the associated outwardly projecting arms 230 such that the tubular insert 212 is at least partially embedded within the polymeric material such that the outwardly projecting arms 230 and at least a portion of the wall member are surrounded by polymeric material. Polymeric material also fills apertures 232 such that the polymeric material in the apertures 232 is contiguously joined to the adjacent polymeric material surrounding the tubular insert 212. In certain embodiments, at least one of the outlet end 217 and/or the inlet end 219 project a distance beyond the outer surface of the polymeric material. In
The outwardly projecting arms 230 have a wall member 219 contacting end 234 and an outer end 236 opposed to the wall member contacting end 234. The wall member contacting end 234 can be formed contiguous to the outer circumferential surface 221 of the wall member 219 and project outwardly therefrom. Alternately, the wall member contacting end 234 of each respective outwardly projecting arm 230 can be connected to the outer circumferential surface 221 of the wall member 219 by any suitable means. The outwardly projecting arms can have any suitable configuration. In the embodiment depicted, one or more of the outwardly projecting arms 230 can be elongated planar members with at least one aperture 232 defined thereon. In certain embodiments, each outwardly projecting arm 230 can include a plurality of apertures 232 defined thereon.
In the embodiment depicted in
It is also within the purview of this disclosure that the outwardly projecting arms 230 be perpendicular to the tubular insert 212 as depicted in
While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
