Fluid reaction surfaces (i.e. – impellers) – Rotor having flow confining or deflecting web – shroud or... – Radially extending web or end plate
Patent
1987-02-17
1988-08-09
Powell, Jr., Everette A.
Fluid reaction surfaces (i.e., impellers)
Rotor having flow confining or deflecting web, shroud or...
Radially extending web or end plate
416188, 416224, 416241A, 415214, 415215, 415DIG5, F04D 702
Patent
active
047624655
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a water pump impeller for a cooling water pump in an internal combustion engine with a metal boss for mounting on a shaft, with a metal reinforcing disk coaxially shaped on to one end of the metal boss and surrounded by plastic, with guide vanes shaped from plastic in the outer circumferential region of the water pump impeller and with plastic parts shaped longitudinally over and beyond the boss.
Water pump impellers are fundamentally known and are used in pumps for transferring cooling water for engine cooling purposes in motor vehicles. Special conditions are made with respect to the materials and the constructional design due to the thermal stresses for this particular use, in which temperatures from approximately -40.degree. to +130.degree. C. can occur. The use of grey cast iron or brass for a water pump impeller leads to the disadvantage that it has a cavitation tendency, i.e. to a destruction of the impeller blades, which leads to pump failure. In addition, there is the disadvantage that the surface is rough, which increases the flow resistance.
Water pumps are also known in which the water pump impeller is made entirely from plastic. However, due to the high heat and cold stresses this construction is not suitable for motor vehicles, because the impellers deflect or sag to such an extent that they run against the casing wall.
Furthermore U.S. Pat. No. 3,251,307 discloses a water pump impeller for use in internal combustion engines, which has a metal boss and a metal reinforcing disk coaxially shaped thereon and oriented substantially at right angles to the boss axis. The reinforcing disk, together with the outer surface of the boss is embedded in a plastic body. Those plastic parts extending over the boss edges in the longitudinal direction of the boss terminate flush with the boss inner face. The plastic body extends radially over and beyond the reinforcing disk and in this outer circumferential region guide vanes are formed in the plastic part.
There is consequently a risk that the area carrying the guide vanes will sag, particularly under thermal stress. It is also unavoidable that as a result of the different expansion coefficients, strains will occur and the plastic will become deformed. It can also not be excluded that at high speeds there will be twisting of the reinforcing disk and water pump impeller, which reduces efficiency.
The problem of the invention is therefore to provide a water pump impeller of the aforementioned type, which is protected against deformation.
This problem is solved in that the reinforcing disk is provided in the vicinity of the guide vanes with an annular disk part and with a revolution paraboloid-like reinforcing region between the boss and the annular disk part running at an acute angle to the boss, that the guide vanes are arranged on the concave side of the reinforcing disk and that the plastic part projecting beyond the boss in the direction of the longitudinal axis terminates at a given distance from the boss inner face to avoid contact with the shaft.
The invention provides the advantage that the water pump impeller is completely reinforced against twisting and is protected against sagging. Thus, the path of the water pump impeller and in particular the guide vanes is maintained in an extremely accurate manner, so that an adjustment is possible in the pump housing with a relatively small tolerance range, so that the pump efficiency can be increased. The reinforcement of the water pump impeller is on the one hand based on the parabola cross-section of the inner circumferential region of the reinforcing disk and on the other hand on the fact that the reinforcing disk is led into the outer circumferential region of the impeller and below the guide vanes. Since, according to the invention, there is also no contact between the plastic and the drive shaft, heating and flowing of the plastic is prevented.
As a result of the inventive arrangement of the guide vanes on the concave side of the reinforcing disk, it is possible to achieve an ext
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Klifa-Fahrzeugteile GmbH + Co.
Powell Jr. Everette A.
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