Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Reexamination Certificate
1999-07-29
2001-02-20
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
C415S196000
Reexamination Certificate
active
06190119
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a multi-channel flow through a turbine impeller pump assembly to cancel the radial pressure loads on the turbine impeller.
In the assembly of turbine impeller pumps, a turbine impeller, keyed to the rotating shaft, rotates within a plane perpendicular to the shaft within the confines of annular liners. As set forth in U.S. Pat. No. 5,137,418, assigned to the assignee of the present invention, the turbine impeller is axially movable with respect to the shaft, to be positioned between the annular liners. Also, such pump assemblies include a single channel flow through the annular liners to the impeller. However, this single channel flow does not compensate for the shaft radial loading caused by hydraulic forces that necessarily occurs within the pump assembly during pumping operations. Such forces cause the shaft and impeller to incur forces and moments and thus move off-center and rotate in an axial plane of the shaft centerline thereby causing interference between the rotating impeller and the stationary liners within the pump assembly unless clearance is provided. Clearance allowances for this deflection is a compromise between a design pressure limit and leakage. Increasing clearance allows more deflection without damage but leakage losses increase to the detriment of efficiency. Increasing leakage reduces the maximum capability. Such interferences caused by pressure above the designed value result in premature pump failures thereby resulting in costly and expensive repair to the pump assembly.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a turbine impeller pump assembly which cancels the radial hydraulic forces that create the moments in the axial plane of the shaft centerline.
It is another object of the present invention to provide a dual channel flow through a turbine impeller pump assembly to cancel the radial loads on the shaft bearings.
It is a further object of the present invention to provide a turbine impeller pump assembly which includes liners enclosing the impeller with each liner having separated flow channels mirrored about the Y-axis, to provide a multi-channel flow through the assembly.
It is still another object of the present invention to provide a turbine impeller assembly which includes suction and discharge ports opposite one another which cooperate with the multi-flow channels in the liner members to produce equal and offsetting pressures on the impeller to allow the impeller to be radially centered. Through the presence of the ramped surface configuration on the surface of the impeller or liner members, the impeller is caused to be axially centered between the outboard and inboard liner members.
It is yet another object of the present invention to provide a turbine impeller pump assembly having equal and opposite pressures on the impeller which eliminates shaft deflection within the pump assembly.
It is yet a further object of the present invention to provide a novel turbine impeller pump assembly which is practical and efficient in operation without shaft deflection and with substantially minimal radial load so that lower capacity bearings may be employed in the assembly.
The present invention is directed to a novel multi-channel flow path of the pumped fluid through a turbine impeller pump assembly which cancels the axial and radial pressure loads on the turbine impeller. A single stage turbine impeller pump assembly includes a motor driving a rotating shaft. The shaft extends through an inboard cover surrounding an inboard liner, an impeller is rotationally fixed to the shaft and an outboard liner is enclosed by an outboard cover. The covers support the liners embodying the channel and provide the fluid paths to and from the liner's inlets and outlets and the exterior of the pump.
The inboard and outboard liners enclose the impeller, which is radially fixed to the shaft to rotate. Each of the liners includes a flow channel mirrored about the Y-axis and which are separated from each other to provide two or dual channels that are separated from one another. The liners are enclosed by inboard and outboard cover or casing members. The inboard and outboard covers are the locations for the inlet and outlet port for the pump, which are mirrored about the X and Y axis and which make them opposite one another. However, it is within the scope of the present invention in that the inlet and outlet port may be positioned radially in the inboard and outboard cover members. The fluid entering the suction port is operatively diverted to the two suction ports on each liner whereby the fluid is then recirculated by the vanes on the impeller. The fluid is propelled around each channel of the liners and exits the two discharge ports in the liners. The discharged fluid is combined to exit through the discharge port of the pump.
The structure of positioning the suction and discharge ports opposite one another and the dual channels of the liners produces equal and opposite pressures on the rotating impeller to cancel the radial loads on the impeller and to facilitate the impeller to self-center itself between the liners. The equal and opposite pressure condition eliminates shaft deflection during pumping operations which results in substantially reduced wear on the impeller and liners and results in significantly lighter loads. The elimination of the vector resultant of the radial hydraulic loads, the subsequent cross-moments in the plane of the shaft centerline and subsequent shaft deflection significantly reduces bearing loads and the associated costs of replacement. This permits the use of sleeve bearings in the pump assembly which allows the use of the pumped fluid as the bearing lubricant when the pumped fluid is a non-lubricating fluid.
The present invention consists of certain novel features and structures details hereinafter fully described, illustrated in the accompanying drawings, and specifically pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit or sacrificing any of the advantages of the present invention.
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MTH Pumps, Series T41 Pricing Pages, dated Mar. 1992.
Roth Paul E.
Roth Peter P.
Wright Bruce C.
Emrich & -Dithmar
Look Edward K.
McAleenan James M.
Roy E. Roth Company
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