A voltage driving apparatus for a portable fluid pump comprising a power source arranged to provide a direct current, a DC gain unit electrically connected, in use, to receive a voltage from the power source and output an amplified voltage, and a DC to AC conversion unit arranged, in use, to receive the amplified voltage from the DC gain unit and output a periodic waveform to drive a piezoelectric actuator in the portable fluid pump. The output periodic waveform comprises a first discrete voltage level and a second discrete voltage level. Each period of the waveform comprises the first voltage level for a first length of time and a second voltage level for a second length of time.

An actuation system for a resonant linear compressor (50), applied to cooling systems, the latter being particularly designed to operate at the electromechanical frequency of said compressor (50), so that the system will be capable of raising the maximum power supplied by the linear actuator, in conditions of overload of said cooling system. Additionally, an actuation method for a resonant linear compressor (50) is disclosed, the operation steps of which enable one to actuate the equipment at the electromechanical resonance frequency, as well as to control the actuation thereof in over load conditions.

A negative pressure wound therapy device includes at least one piezoelectric pump and a control circuit. The control circuit is configured to generate a first control signal to control operation of the at least one piezoelectric pump, the control signal having a first root mean square (RMS) voltage, transmit the first control signal to the at least one piezoelectric pump, identify at least one of a change of state of the at least one piezoelectric pump or an expiration of a duration of time associated with operation of the at least one piezoelectric pump, responsive to identifying the at least one of the change of state or the expiration of the duration of time, generate a second control signal having a second RMS voltage less than the first RMS voltage, and transmit the second control signal to the at least one piezoelectric pump.

Method for controlling a linear pump (9) of a vapour recovery system in a fuel dispensing unit (1). The linear pump (9) is flow controlled by a signal. The method comprises applying (SI) a known voltage to a solenoid coil (10) of the linear pump (9) for a predetermined time period, measuring (S2) a current consumption of the solenoid coil (10) during the predetermined time period, and adjusting (S3) the signal based on the measured current consumption. The invention also relates to a vapour recovery system for recovering vapour from a motor vehicle tank via a fuel dispensing nozzle (7) to a vapour tank.

The invention relates to a method for controlling a linear pump of a vapour recovery system in a fuel dispensing unit. The linear pump is flow controlled by a signal. The method comprises applying a known voltage to a solenoid coil of the linear pump for a predetermined time period, measuring a current consumption of the solenoid coil during the predetermined time period, and adjusting the signal based on the measured current consumption. The invention also relates to a vapour recovery system for recovering vapour from a motor vehicle tank via a fuel dispensing nozzle to a vapour tank.

A linear compressor includes, a cylinder, a piston configured to reciprocate inside the cylinder, a motor configured to supply driving force to the piston, a detector configured to detect a motor current and a motor voltage that are applied to the motor, and a controller configured to estimate a stroke of the piston based on the motor current and the motor voltage and to determine a phase difference between the stroke and the motor current. The controller is configured to detect operation information of the linear compressor, determine whether to perform a resonance operation based on the operation information, and control operation of the motor to allow the phase difference to be within a preset phase range.

Provided are a linear compressor and a linear compressor control system that do not require a sensor for detecting a position of a mover, and can compute a mover position with high accuracy, in consideration of position dependency of an induced voltage constant. A linear compressor 20 includes a field element 11 having a first end connected to elastic bodies (201a and 201b) and including a permanent magnet 111, an armature 12 having a winding 122 wound around a magnetic pole 121, and a linear motor 10 that causes the field element 11 and the armature 12 to reciprocate relatively in an axial direction. A stroke of a piston is controlled so that a portion where a gradient of an induced voltage when the induced voltage computed on the basis of a voltage command value output to the linear motor 10 and a value of a current flowing through the winding 122 is at a predetermined value is within a predetermined range corresponds to a top dead center and/or a bottom dead center of a stroke of a piston 212 connected to a second end of the field element 11.

A fluid control device includes a piezoelectric pump, a piezoelectric pump, a valve, and a container. The piezoelectric pump and the piezoelectric pump repeat the operation and the stop in accordance with a drive control cycle. The valve starts a control to close at the start timing of one cycle of the drive control cycle and starts a control to open at the stop of the piezoelectric pump and the piezoelectric pump. The time from the start timing of one cycle of the drive control cycle to the time at which the piezoelectric pump on the upstream side pump reaches a normal operation drive voltage is longer than the time from the start timing to the time at which the piezoelectric pump on the downstream side reaches a normal operation drive voltage.

A linear compressor includes a cylinder, a piston, a linear motor configured to drive the piston, a current detection unit configured to sense a current in the linear motor, a relay configured to change an operation mode of the linear motor, and a control unit configured to set at least one parameter for determining a stroke of the piston according to the operation mode. The control unit is configured to: determine a first magnitude of a first current in the linear motor based on a state of the relay being in a first state, determine a second magnitude of a second current in the linear motor based on the relay being switched to a second state from the first state, compare the first magnitude to the second magnitude, and based on the comparison of the first magnitude to the second magnitude, determine whether the relay fails to operate.

A pump system contains a vibration actuator which can be electromagnetically driven by applying an alternating-current voltage E thereto, a sealed chamber connected to a suction port and a discharge port, and a movable wall for changing a volume of the sealed chamber. The movable wall is displaced due to drive of the vibration actuator to supply fluid in the sealed chamber into a target object. The pump system controls an effective value of the alternating-current voltage E so that an amplitude Y of the vibration actuator is constant.