US 3846045 A
This composite impeller is intended for use in a pump incorporated in the cooling system of an internal combustion engine and comprises a metal hub permitting the tight fitting of the impeller on the pump shaft, and an impeller proper having one outer peripheral portion of said hub embedded therein, said impeller consisting of a mixture of thermosetting resin having a low coefficient of water absorption when heated and of a water-repellent filler not liable of undergoing appreciable changes in its dimensions in the presence of water; this composite impeller is capable of operating satisfactorily in engines having rotational speeds of up to 9,000 r.p.m. under temperatures of the order of 130 DEG C.
Description (OCR text may contain errors)
United States Patent 11 1 .1111 3,846,045 Mincuzzi 1 1 Nov. 5, 1974 [5 PUMP IMPELLERS FOR COOLING 3,408,944 11/1968 Belonger 01 al 416/241 A S S F 3,659,471 5/1972 Marsch 416/224 UX 3,751,181 8/1973 Hayashi 416/132  Inventor: Antonio Mincuzzi, M1lan, Italy 73 A s I l FOREIGN PATENTS OR APPLICATIONS 33': i 'gg 'fi e debMecanque 1,115,585 10 1961 Germany 416/241 A r e e 1,950,139 4/1971 Germany 416/241 A Luxembourg 359,036 1 1962 Switzerland 416 224  Filed: Apr. 9, 1973 1 pp No: 349,029 Primary ExammerEvcrette A. Powell, Jr.
 ABSTRACT Forelgn Apphcatlon Prwmy Data This composite impeller is intended for use in a pump Apr. 17, France incorporated in the cooling ystem of an internal ombustion engine and comprises a metal hub permitting  US. Cl 416/230, 416/224, 416/241 the tight fitting of the impeller on the pump Shaft, and  Int. Cl. F0441 7/02 an impeller proper having one Outer peripheral  meld of Search 416M347 241 A, tion of said hub embedded therein, said impeller con- 116/224 174; 415/ A sisting of a mixture of thermosetting resin having a low coefficient of water absorption when heated and of a  References C'ted water-repellent filler not liable of undergoing appre- UNITED STATES PATENTS ciable changes in its dimensions in the presence of wa- 2,115,997 5/1938 Morse 416/ this p site impeller is capable of operating 2,220,669 11/1940 Allen 416/241 X satisfactorily in engines having rotational speeds of up 3,224,509 12/1965 Thompson... 416/241 X to 9,000 rpm. under temperatures of the order of 3,233,678 2/1968 Wilk 416/241 3,256,939 6/1966 Novak 416/135 3,318,388 5 1967 Bihlmire 416 240 x 5 Claims, 14 Drawmg Figures PUMP IMPELLERS FOR COOLING SYSTEMS OF I.C.E.
BACKGROUND OF THE INVENTION.
This invention relates in general to pumps of the type used in the cooling systems of internal combustion engines and has specific reference to an improved impeller or rotor for such pumps.
It is known that heretofore, these impellers consisted mainly of cast iron and more recently of pressed metal, in contrast with the impellers of modern washing machines which consist essentially of plastic material.
Yet, the advantages to be expected from the use of plastic materials in the manufacture of pump impellers for the cooling system of internal combustion engines are well known; low cost, easy moulding and stripping under mass-production conditions, easy obtaining of A functional shapes with smooth surfaces permitting an improved efficiency in actual service, light weight ensuring a satisfactory dynamic balance, reduction of noise and vibration, etc.; unfortunately, notwithstanding the considerable research and test works accomplished in this field, it has not been possible up to now and so far as the Applicant is aware to manufacture impellers of plastic material capable of withstanding satisfactorily and for a reasonably long time the specific conditions of operation in pumps equipping the cooling systems of internal combustion engines.
It is obvious that these impellers operate under conditions differing considerably from those encountered in laundry washers and dishwashers; in fact, in these machines the rotational speed is always below 3,000
r.p.m. and the temperature not in excess of 98C; on the other hand, in internal combustion engines rotational speeds as high as 9,000 r.p.m. and temperatures of the order of 130C are frequently encountered; therefore, the mechanical and thermal stresses involved differ completely and it was currently admitted that plastic materials could not withstand such stresses, so that the use of these materials had to be definitely precluded in the manufacture of impellers for the pumps of cooling systems of internal combustion engines.
SUMMARY OF THE INVENTION.
Now it was found according to the present invention that it was possible to obtain a pump impeller for the cooling systems of internal combustion engines which consisted essentially of plastic material and had a strength at least equal or comparable to that of conventional metal turbines; to this end, this impeller is characterised in that it comprise a metal hub adapted to be force-fitted to the pump shaft, the impeller proper being moulded on said hub and consisting of a mixture of thermosetting resin having a low coefficient of water absorption under extreme temperature conditions, with a water-repellent filler capable of preserving its original dimensions in the presence of water.
Thus, notably, it was found that a filler consisting of short asbestos fibres was perfectly suited for the purpose, inasmuch as the cost of these fibres is very low;
\ glass fibres may also be used provided that they are of As a thermosetting resin, certain formophenolic resins (of the Notolaque" type are adequate for the purpose.
According to a typical form of embodiment of this invention, the impeller fitted to a metal hub comprises an impeller body constituting the blade hub and having a diameter increasing gradually towards the outer periphery, said body being bounded on the inner side by an internally concave surface from which the impeller blade project; the maximum diameter of the impeller body is preferably the same as the outer diameter of said blades, so that the assembly is inscribed in a cylinder.
If desired, the impeller body may comprise on its rear face a sealing ring adapted to be kept in frictional contact with a counter-ring associated with the adjacent wall of the water pump in order to provide the necessary fluid-tightness; if desired, this counter-ring may be fitted in the impeller body proper with the interposition of an elastic material such as rubber.
This type of impeller can easily be force-fitted to the pump shaft by using a press and a suitable jig; the press fit requires in this case a force of the order of 200 to 300 DaN when the fit or clamping pressure is of the order of a few hundredths of mm between the hub and the pump shaft, the latter having a diameter of 16 mm,
for example. a
When the degree of precision of the hub and shaft is relatively high, the fitting steps is not attended by any difficulty; on the other hand, if it is desired to reduce costs by resorting to a less accurate manufacture, the maximum shrinking force obtained through a proper selection of the tolerances between a hub of minimum diameter and a shaft of maximum diameter must be increased. As a result, at the limit, the filled thermosetting resin constituting the impeller proper (which has one portion of the hub embedded therein) would break up due to the overstepping of its elastic elongation limit.
According to a modified form of embodiment of this invention which is intended for avoiding this inconvenience while affording a considerably greater safety margin under mass-production conditions, the metal hub of this impeller comprises a sleeve constituting the hub proper which is connected through a curved intermediate portion to an end or outer portion and it is this portion alone that is embedded in the plastic impeller proper.
BRIEF DESCRIPTION OF THE DRAWINGS.
The drawings attached herewith illustrate diagrammatically by way of example typical forms of embodiment of the present invention. In the drawings:
FIGS. 1 to 4inclusive are longitudinal sections showing four different forms of embodiment of the composite impeller of this invention;
FIGS. 5 and 6 are a diametral section and a front view, respectively, of the metal hub utilized in this invention;
FIG. 7 is a diametral section illustrating on a larger scale a modified form of embodiment of the impeller of this invention;
FIGS. 8 to 12 illustrate other modifications of the metal hub incorporated in the pump impeller;
FIG. 13 is a sectional view of another form of embodiment of this invention, showing the impeller fitted to the pump shaft, and
FIG. 14 is another modified form of embodiment of the metal hub of the pump impeller.
DESCRIPTION OF THE PREFERRED EMBODIMENT.
The impellers or rotors illustrated comprise a metal hub 1 adapted to be pressor force-fitted to the pump shaft, this hub 1 constituting an insert of which one portion is adapted to be embedded by molding in a sleeve or impeller body 2; to this end, each metal hub has an integral castellated outer peripheral portion 3 affording a reliable anchoring of the hub 1 in the body 2; the impeller body may have a wide range of shapes and dimensions as required for the specific use for which the impeller is intended.
The diameter of the impeller body 2 illustrated in FIGS. 1 and 2 increases gradually from its front end 4 to its rear end 5; on the front side, it is bounded by a concave surface 6 facing forwards and upwards, and comprises in this example six radial blades 7 of which the outer edge 8 is adapted to be inscribed in a cylinder concentric to the impeller axis; furthermore, on its rear side the impeller body 2 has fitted therein a sealing ring 9 with the interposition of a flanged rubber ring 10.
In the forms of embodiment illustrated in FIGS. 3 and 4 of the drawings the blades are not radial and therefore their upper and lower sections 11, 12 taken through a same diametral plane differ in shape; the sealing ring 13 of FIG. 3 is fitted to the tubular rear extension 14 of the impeller body 2 with the interposition of a flanged rubber ring 15 formed with an integral annular bead 16 providing a static seal between the shaft 17 to which the impeller is fitted and the impeller body; alternatively, in the form of embodiment illustrated in FIG. 4 the sealing ringis replaced by a deposit 18 of suitable material of refractory or other nature, formed by using a plasma gun.
The pressed metal hub 22 illustrated in FIG. 7 and force fitted to the shaft 20 is so shaped that its outer peripheral portion 26 remains static while the hubforming portion and the curved intermediate portion 24 expand slightly during the press-fitting operation. The plastic impeller 21 is driven and retained positively in the metal hub by means of the peripheral outer portion 26, a hollow space 23 being easily obtained on either side of the intermediate portion 24 during the molding operation. It is clear that the axial off-set between the portions 24 and 26 of this hub is characterised by an indirect relationship between the distortions of portion 24 and those of portion 26, thus reducing their magnitude.
Other forms of embodiment of hubs suitable for different impeller configurations as well as other positions for centrally anchoring the impeller to the hub are illustrated in FIGS. 8 to 12 inclusive of the drawings, which are self-explanatory.
In the form of embodiment illustrated in FIGS. 13 and 14 the hub is machined from bar stock metal on a lathe, so that substantial differences in thickness between the various cross-sectional portions can be obtained.
Thus, it was found that for the same purpose and with a view to further widen the field of the present invention it was advantageous to incorporate an elastomer or other flexible material in the thermosetting resin mentioned hereinabove, in order to improve the flexibility of the molded impeller; however, this addition should be kept within reasonably low limits, for example less than 30 percent by weight, in order to avoid any detrimental influence on the characteristics of the basic mixture.
Of course, it will readily occur to those conversant with the art that the specific forms of embodiment shown, described and suggested herein should not be construed as limiting the scope of the invention, since various modifications and changes may be brought thereto without departing from the basic principle of the invention as set forth in the appended claims. Thus, the shape of the impeller body the number, arrangement and profile of the blades may vary considerably as a function of the specific function devolved to the impeller.
That is claimed as new is:
1. Pump impeller for cooling systems of internal combustion engines, comprising a metal hub adapted to be force fitted to an engine shaft and having an outflaring portion at its outer end, a sleeve molded from thermosetting resin having a low hot-water absorption coefficient and a thickness increasing from its inner face to its outer face anchored to the outflaring hub portion, a rubber ring fitted into the rear face of said sleeve, a packing ring securing said rubber ring to the rear face of said sleeve, and impeller blades having their outer edges inscribed in a cylinder concentric to the impeller axis and formed integrally with said sleeve.
2. Pump impeller as claimed in claim I, wherein said sleeve is hollowed out on each side of its portion anchored to the hub outflaring portion.
3. Pump impeller as claimed in claim I, wherein said hub is formed with a U-sectioned radial outflaring portion of which the free end is bent and embedded in the sleeve material.
4. Pump impeller as claimed in claim 1, wherein said molded sleeve comprises a formophenol resin containing an asbestos fiber filler.
5. Pump impeller as claimed in claim 1, wherein said molded sleeve comprises a formophenol resin containing a filler consisting of at least thirty percent of a suitable elastomer.