Drive system for deep well pump

Abstract

A drive system is provided for driving the pump rod of a deep well pump. The drive system includes a lift cylinder having a piston movable therein connected to the pump rod of the well pump. The lift cylinder piston is driven by fluid pressure provided from a motor having a piston slidable within a cylinder. The motor piston is driven by fluid pressure provided by a pump. A control valve is operated in response to the movement of the lift piston to control the flow of fluid from the pump to the motor. A pressure relief valve is connected between the pump and the motor and diverts fluid pumped by the pump from the motor when the fluid pressure between the pump and the motor exceeds a predetermined level. A vent is provided in the lift cylinder above the piston to permit the free movement of the lift cylinder piston during operation and to accommodate movement of the lift piston caused by expansion of fluid and gases in the system. The drive system further includes a fluid control valve for controlling the rate of fluid flow from the motor to the lift cylinder. In another embodiment of the invention, the motor piston is driven by a power unit which reciprocates the motor piston to direct fluid to the lift cylinder for operation of the lift piston.

Dependencies are inferred from the claim text.