A system and method for dispensing fluid including a pump having a stepper motor operably connected to a pump head. The pump head has an inlet and an outlet. The inlet is adapted to be in fluid communication to a fluid reservoir. A controller is operably connected to the motor. The controller drives the motor wherein a speed and an acceleration of the stepper motor is selected to overcome adhesion between the dispense tip and the dispensed fluid. A dispense tip formed of a hydrophobic material is in fluid communication with the outlet of the pump head.

Disclosed is a supplying device of fixed colorants volume for a colorant dispenser. The supply device includes: a colorant source; a cylinder body having multiple piston cylinders arranged around a circumferential direction thereof; a swashplate having an oblique surface and arranged substantially coaxially with the cylinder body; multiple piston mechanisms, where each piston mechanism includes a piston rod and a piston connected to the piston rod, the piston rod has a rolling abutment structure abutting against the oblique surface, and the piston is constructed to be capable of making a stroke movement in the corresponding piston cylinder by means of rotation of the swashplate; an actuator for actuating the swashplate; a controller operatively connected to the actuator to control the amount of rotation of the swashplate; and an outlet for dispensing a colorant. Preferably, the supply device further includes an axial reset mechanism and a circumferential reset mechanism.

Disclosed is a supplying device of fixed colorants volume for a colorant dispenser. The supply device includes: a colorant source; a cylinder body having multiple piston cylinders arranged around a circumferential direction thereof; a swashplate having an oblique surface and arranged substantially coaxially with the cylinder body; multiple piston mechanisms, where each piston mechanism includes a piston rod and a piston connected to the piston rod, the piston rod has a rolling abutment structure abutting against the oblique surface, and the piston is constructed to be capable of making a stroke movement in the corresponding piston cylinder by means of rotation of the swashplate; an actuator for actuating the swashplate; a controller operatively connected to the actuator to control the amount of rotation of the swashplate; and an outlet for dispensing a colorant. Preferably, the supply device further includes an axial reset mechanism and a circumferential reset mechanism.

Pump controller: when operation device receives neither first or second operation, outputs standby rotation speed as command rotation speed to engine controller, standby rotation speed being lower than selected reference rotation speed; when operation device receives first operation, changes command rotation speed from standby rotation speed to first target rotation speed in such a manner that as an amount of first operation increases, increasing rate of command rotation speed decreases gradually; when operation device receives second operation, changes command rotation speed from standby rotation speed to second target rotation speed in such a manner that as an amount of second operation increases, increasing rate of command rotation speed increases gradually; and feeds command current to a solenoid proportional valve that outputs secondary pressure to regulator that adjusts tilting angle of a pump, such that a discharge flow rate of the pump is proportional to amount of first and second operation.

A hydroelectric power system and pump suitable for the system are disclosed which can make efficient use of the energy available in water flows with considerably variable flow rates. A simple, compact variable displacement axial piston pump can be operated so as to provide an essentially constant output pumping pressure and variable output volume that varies efficiently in accordance with water flow rate. The system is particularly suitable for shoreline tidal power generation and provides firm power output throughout the tidal slacks occurring during the tidal reversals.

A lift apparatus and method for driving a downhole reciprocating pump is disclosed and includes a hydraulic cylinder having a piston and a hydraulic fluid port, the piston being coupled to a rod for driving the reciprocating pump, the piston being moveable between first and second ends of the cylinder in response to a flow of hydraulic fluid through the hydraulic fluid port. A variable displacement hydraulic pump is responsive to a displacement control signal to draw hydraulic fluid from a reservoir and to produce a controlled flow of hydraulic fluid at the outlet. The apparatus also includes a valve connected between the hydraulic fluid port and the reservoir, the valve being responsive to a valve control signal for controlling discharge of hydraulic fluid from the hydraulic fluid port of the cylinder back to the reservoir to facilitate movement of the piston through a downstroke away from the second end toward the first end of the cylinder. The apparatus further includes a first sensor located proximate the first end of the cylinder and operable to produce a first signal indicating a proximity of the piston to the first sensor, a second sensor located proximate the second end of the cylinder and operable to produce a second signal indicating a proximity of the piston to the second sensor, and a controller operably configured to generate the displacement control signal and the valve control signal in response to receiving the first signal and the second signal.

A rotatable piston assembly for a reciprocating piston type hydraulic machine includes a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine.

A rotatable piston assembly for a reciprocating piston type hydraulic machine includes a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine.

A rotatable piston assembly for a reciprocating piston type hydraulic machine includes a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine.

A pump-regulator combination includes first and second pumps, a control valve, first orifice, and pilot valve. The first pump is configured to pump fluid from a tank to a first point. The control valve is configured to control pressure and/or delivery flow at the first point by adjusting a displacement volume of the first pump. The second pump is configured to pump fluid from the tank to a second point, through the first orifice, and back to the tank. A highest load pressure of the actuator is connected to a third point. The pilot valve includes an adjustable second orifice connected to the third point, via a fourth point, and the tank to pass fluid from the actuator to the tank. A pressure at the second point acts to close the second orifice. A pressure of the fourth point acts to adjust the control valve.