The present invention is a piezoelectric actuator drive method, a piezoelectric actuator drive circuit, and a piezoelectric actuator drive system capable of causing a piezoelectric element to vibrate in a maximum amplitude state. The piezoelectric actuator drive circuit includes: an obtainment unit that obtains operation information pertaining to operation of the piezoelectric element in a period that is a part of one cycle of a drive cycle in which the piezoelectric element is driven; and a control unit that performs feedback control of a drive parameter for driving the piezoelectric element based on the operation information.

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.

An electric pump includes a pump unit, a motor and a controller. The pump unit is configured to pump fluid by a rotating operation. The motor is a brushless direct-current motor and configured to rotationally drive the pump unit. The controller is configured to control a current to be supplied to the motor. The controller is configured to switch between voltage control for controlling the current to be supplied to the motor based on a target voltage and current control for controlling the current to be supplied to the motor based on a target current.

A linear motor compressor including a compressor housing and a cylinder housing having a plurality of opposing compression chambers. A piston freely reciprocates within the cylinder housing using a linear electric motor. A piston position feedback control system provides adaptive current output as a function of position feedback and/or velocity feedback from the piston and/or the electric motor, to directly power and control the electric motor, wherein the piston reciprocates without assistance from a mechanical spring or other equivalent centering force.

A pump device includes a first piezoelectric pump, a second piezoelectric pump connected in series to the first piezoelectric pump on an upstream side of the first piezoelectric pump, a driver unit that supplies alternating-current input power to the first piezoelectric pump and the second piezoelectric pump, and a distribution setting unit that sets a distribution ratio of the input power to be supplied from the driver unit to each of the first piezoelectric pump and the second piezoelectric pump, wherein the distribution setting unit sets a ratio of the input power for the second piezoelectric pump to the input power for the first piezoelectric pump to a value greater than 1 and equal to or less than 1.57.

The control module includes a drive circuitry that drives the linear compressor based on a control signal, a detector that detects a motor current and a motor voltage corresponding to a motor of the linear compressor, an asymmetric current generator that generates an asymmetric motor current by applying a current offset to the detected motor current, and a controller that generates the control signal based on the asymmetric motor current and the detected motor voltage. Such a control module may increase a maximum freezing capacity by appropriately (or optimally) designing (setting) an initial value of a piston in a driving area or an operation area (or a high-efficiency driving area) of a compressor by considering the efficiency aspect, and executing an asymmetric operation in a high-load driving area (or a high freezing capacity driving area).

A control valve includes: a first valve to control a flow rate of refrigerant flowing from a discharge chamber to a control chamber of a compressor; a second valve to control a flow rate of the refrigerant flowing from the control chamber to a suction chamber; a solenoid to generate a drive force in a first valve closing direction and a second valve opening direction; a biasing member to generate a biasing force in an first valve opening direction and a second valve closing direction; and a pressure sensing part to sense a pressure in the suction chamber or the control chamber, and generate a counterforce against the drive force. A state in which both of the first and second valves are open is present during an increase in the current supplied to the solenoid from zero to an upper limit current value, and an increase rate of an opening degree of the first valve is increased during a decrease in the current supplied to the solenoid, a predetermined lower limit current value being an inflection point of the increase.

Disclosed is a method for managing a piston pump using a computer of a vehicle, the pump including a guide, a piston slidably mounted in the guide, and a solenoid, suitable for moving the piston, the method including, as long as the fuel pressure in the compression chamber of the pump is below a predetermined pressure threshold, a step of the computer controlling the solenoid in order to move the piston to its high position, and a step of the computer detecting that the predetermined pressure threshold has been exceeded when the current value, measured after a predetermined period, is greater than or equal to a predetermined reference value so that the computer ceases to control the solenoid.

An apparatus and a method may control a compressor. The apparatus may control a motor (included in a compressor) such that the motor quickly repeats turn-on and turn-off operations in a cooling power supply time period/section, thereby enabling the compressor to compress refrigerant in the cooling power supply time period/section. Thus, cooling power of a refrigerator may change while the compressor operates with maximum efficiency.

In order to improve a refrigerant compressor, including a compressor unit having a compressor housing and at least one compressor element that is arranged in the compressor housing, for compressing refrigerant, and further including a drive unit having a drive housing and an electric motor that is arranged in the drive housing and connector terminals that are arranged on the drive housing, for the electric motor, and further including an electronic functional unit, such that the connection between the refrigerant compressor and the electronic functional unit is achievable as simply as possible, it is proposed that the connector terminals should be provided in a housing that is arranged on the drive housing, and that an electronic functional unit which performs at least one compressor function should be provided in the housing.