There is provided a wobble plate piston water pump for use in a pressure washer and driven by a driving source, the water pump includes a pump body, a wobble plate, four or more pistons and a water passage defined by a water inlet and a water outlet. The driving source being electric powered and having a power consumption of less than or equal to a 15 ampere draw at 120 volts or 220 volts or the driving source being gas powered and having an engine displacement of less than or equal to 250 cubic centimetres.

A fluid circulation monitoring system includes a distributed processing system having a first processor located on-premises near a space filled with a circulating fluid and a second processor located off-premises. The first processor and the second processor are in communication with one another. A sensor is operatively connected to the first processor and senses at least one parameter associated with a flow rate of fluid through the circulation system. The distributed processing system is configured to process the at least one parameter and derive a volumetric fluid flow rate through a fluid pump which propels the fluid through the circulation system. Pattern recognition is applied to the at least one parameter to detect maintenance events and predict the need for maintenance events.

A high pressure pump including a linear actuator having a servo motor to axially rotate a hollow rotor shaft in alternating directions, the servo motor having a stator positioned co-axially around the hollow rotor shaft with an interior of the rotor shaft being co-axially coupled to a drive member to convert axial rotation into reciprocal displacement, the drive member being constrained against linear movement and supporting a shaft. At least one piston is coupled to the shaft and the piston is arranged within a cylinder to define a pumping chamber, whereby alternating rotation of the rotor shaft causes reciprocal linear displacement of the piston to pressurize fluid in the pumping chamber. A drive mechanism includes a controller coupled to a servomotor and an encoder to measure movement of the hollow rotor or output shaft and send a feedback signal proportional to the movement to the controller.

A method for detecting a blocked valve of a coolant compressor including a drive unit and a piston-cylinder unit for cyclical compression of a coolant, wherein the drive unit has an electric motor for driving the piston-cylinder unit, monitors the speed () of the electric motor. A maximum speed (.sub.max) of the electric motor is initially detected, and the following steps are carried out, as long as the speed () of the electric motor substantially corresponds to the maximum speed (.sub.max): determining a maximum value X.sub.max of a monitoring parameter (I, T) of the coolant compressor (1); determining a value X.sub.t1 of the monitoring parameter (I, T) after a first time period (t1) after determining the maximum value X.sub.max; detecting a blocked valve if X.sub.t1 is less than X.sub.max and (X.sub.maxX.sub.t1)/X.sub.max.sub.X applies, wherein .sub.X is predetermined.

A method is provided for braking a compressor of a refrigeration appliance, of an air conditioning appliance or of a heat pump in which the compressor has a brushless motor with windings and a controller for braking the motor. The controller is configured to brake the brushless motor by using a braking current in a controlled manner starting from an operating rotational speed, in which the braking current during the controlled braking is dependent on induced voltages determined before the controlled braking. The method for braking includes rotating the motor at an operating rotational speed, receiving a signal for decelerating, braking or slowing down, determining voltages induced in the windings and supplying a braking current having a decreasing frequency to the windings, in which the braking current during the braking is dependent on the previously determined induced voltages. A compressor and a refrigeration appliance having the compressor are also provided.

A method for operating a linear compressor includes providing a current controller, a resonance controller and a clearance controller. The current controller, the resonance controller and the clearance controller are configured for regulating operating parameters of a motor of the linear compressor. By managing priority between the current controller, the resonance controller and the clearance controller, the method may assist with efficiently operating the linear compressor while also maintaining stability.

An electric oil pump includes a pump unit, rotating to make oil flow, a motor driving the pump unit, a control unit exerting driving control on the motor, and a housing accommodating the pump unit, the motor, and the motor control unit. In the electric oil pump, the motor control unit directly receives detection information of a temperature sensor detecting a temperature of the oil and exerts driving control on the motor based on the detection information.

A compressor provided with a compressor element, a motor configured to drive said compressor element and an electronic pressure switch. The electronic pressure switch includes a pressure sensor; a current sensor; a microprocessor unit including a first input port and a second input port; a first communication unit; and a second communication unit. The electronic pressure switch includes a housing. The microprocessor unit, the pressure sensor, the current sensor, the first communication unit and the second communication unit are integrated in said housing.

To predict and detect a failure in a compressor provided in an air conditioner, the air conditioner is provided with: a heat exchanger; the compressor; piping connecting the heat exchanger and the compressor with each other; and a control unit controlling the compressor and having a compressor failure predicting and detecting means, and in this air conditioner, the compressor failure predicting and detecting means of the control unit includes: a current detecting part detecting a driving current driving the compressor; a pulsation detecting part detecting pulsation in a driving current detected by the current detecting part; and an anomaly determining part predicting or detecting any failure in the compressor based on a magnitude and a duration of pulsation in a driving current detected by the pulsation detecting part.

A hydraulic pressure supply system includes: a mechanical oil pump; an electric oil pump; an electric motor that drives the electric oil pump; a control device that controls the operation of the electric oil pump by manipulating a power-supply voltage or a power-supply current to the electric motor; a check valve that is installed at an upstream position relative to a junction pipe of an outlet-side pipe of the mechanical oil pump and an outlet-side pipe of the electric oil pump; and a hydraulic pressure measurement circuit that measures a hydraulic pressure of the outlet-side pipe of the electric oil pump. The control device starts supplying electric power to the electric motor to thereby start drive of the electric oil pump before the mechanical oil pump stops operating, and limits the power-supply current to the electric motor to a first current or less during a time period between the start of the drive of the electric oil pump and the time when the hydraulic pressure measured by the hydraulic pressure measurement circuit exceeds a prescribed outlet hydraulic pressure.