| 摘要 |
The present invention provides a pump drive assembly for a deep well, submersible, progressing cavity pump that includes an internal hydraulic pump for slowing the counter rotation of the polished rod induced by recoil in the sucker rod. The pump drive assembly includes a housing enclosing a hydraulic fluid reservoir and a gear chamber separate from the reservoir. A drive shaft extends into the housing and includes a drive gear integral wide or keyed to the drive shaft. A main shaft also extends into the housing and includes a main gear integral with or keyed to the main shaft. The main gear is engaged with the drive gear within the gear chamber, where the gear chamber includes an inlet and an outlet channel providing fluid communication between the gear chamber and the reservoir, so that the gears form a reversible gear pump within the housing. The reversible gear pump operates to pump hydraulic fluid from the reservoir into the gear chamber and back into the reservoir. During normal operation of the drive assembly, the gear pump will operate in the forward direction; but when the polished rod is caused to recoil, the gear pump will be caused to operate in the reverse direction. Therefore, the pump drive assembly also includes a flow resistor coupled to at least one of the inlet and outlet channels for retarding the flow of the hydraulic fluid when the gear pump is operating in the reverse direction, thus slowing counter-rotation of the polished rod during recoil.
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