Patent Application
20050169783
1. Field of Invention
The present invention relates to a method and apparatus for adjusting an impeller coupled to a motor in relation to an impeller assembly; and more particularly relates to a method and apparatus for adjusting such an impeller in a close coupled centrifugal pump.
2. Description of Related Art
Internal bushings or shims to set impeller clearance for optimum pump performance are known. However, current devices are difficult to set accurately and reside in the process fluids where they are susceptible to corrosion/erosion. Current methods and apparatus require the user to completely assemble the pump, then insert a feeler gauge into the suction (which is often only 1″ diameter) to set the impeller-to-casing clearance. Then the unit must be disassembled and the appropriate bushing or shims added to the shaft behind the impeller hub. The units are then reassembled and the clearances re-checked. Since gasket and/or o-ring compression can be different at each assembly, this can lead to this process being repeated a multitude of times before it is correct. Due to this complicated process, many times impeller clearances are simply set “close” and hereby cause the pumps to operate under conditions which produce less flow and head as well as consume more energy. Since these bushings/shims are in the process flow, the metallurgy must be selected to be compatible with the pump fluid to avoid corrosion attack, which in many cases is very costly.
The present invention provides a new and unique a method and apparatus for adjusting an impeller in a close coupled pumping device. The method features the steps of: tightening mounting bolts so as to move the motor and impeller assembly of the pumping device forward until the impeller touches a casing; inserting a feeler gauge in radial slots in a frame adapter and measuring a gap between a housing of the motor and the frame adapter; determining a required impeller adjustment distance by adding the desired impeller running clearance to the feeler gage thickness determined by measuring the gap at the radial slots; selecting at least one shim having a thickness that corresponds to the desired impeller adjustment distance; loosening the mounting bolts and threading jacking bolts arranged in the rear of the pump frame adapter so that the jacking bolts push against the housing of the motor and the shims can be inserted into the radial slots; inserting the shims into the radial slots; backing out the jacking bolts; and securing the mounting bolts locking the motor and impeller assembly in position so that the impeller is at the desired impeller adjustment distance in relation to the casing.
In accordance with the present invention, the frame adapter assembly features a frame adapter having four radial slots to enable access to the gap for measurement with a feeler gauge and for insertion of the shim to accurately set the impeller clearance. The invention is not limited to using separate mounting bolts and/or jacking bolts but includes any type of jacking/locking bolt assembly (single or multiple).
One advantage of the invention is that it allows impeller adjustment externally while the unit is fully assembled. Tolerance can be renewed at any time to maintain optimum unit performance without disassembly, thereby extending the unit life and lowering operating costs. The invention also does not require any internal bushings or shims that can corrode in the process fluid.
The drawing, not drawn to scale, includes the following Figures:
The pumping device 10 has jacking bolts 1 in the rear of the pump frame adapter 2 that push against a motor housing 3 of the motor 6.
During assembly, the pump frame adapter 2 is mounted to the motor 6 and secured with mounting bolts 4. The mounting bolts 4 should all be tightened until the pump frame adapter 2 is tight against the motor housing 3. A seal 18 is pushed on to the impeller shaft 13 and seated into the pump frame adapter 2. The pump seal assembly consisting of a gland 17 and a pump seal 19 are positioned on the impeller shaft 13. A seal chamber 16 is mounted on the pump frame adapter 2 and secured with screws (not shown). The gland 17 is then secured to the seal chamber 16 with a gland stud and nut 21. The impeller 11 is attached to the impeller shaft 13. The mounting bolts 4 are loosened 2 to 3 turns and the jacking bolts or screws 1 are threaded further into the frame adapter 2 until the impeller 11 contacts the seal chamber 16. A casing 14 is mounted on the seal chamber 16 and casing bolts 15 are inserted through the holes in the pump frame adapter 2 and threaded into the casing 14. The casing bolts 15 are tightened.
Once the unit is assembled, the jacking bolts 1 are then backed out.
Then the mounting bolts 4 are tightened moving the motor 6 and the impeller assembly 12 forward until it touches the casing (turning the impeller shaft 13 to make sure contact is made). Next, a feeler gauge (not shown) is inserted at the radial slots 20 (See also
The mounting bolts 4 are then secured locking the impeller assembly 12 in position, as shown in
The pump frame adapter 2 is unique in that it has the four radial slots 20 to enable access to the gap G for measurement with the feeler gauge (not shown) and for insertion of the shims 5 to accurately set the impeller clearance, as best shown in
The invention is not limited to using separate mounting bolts 4 and/or jacking bolts 1 and may include any type of jacking/locking bolt assembly (single or multiple).
The scope of the invention is also intended to include using the present invention on close coupled motor/centrifugal pumps close coupled motor/positive displacement pumps or other electric motor driven products that require adjustment of internal components via an external device.
Accordingly, the invention comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth.
It will thus be seen that the objects set forth above, and those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
