A swash plate type piston pump includes a plurality of pistons, a cylinder block including a plurality of cylinders for housing the pistons, a swash plate for reciprocating the pistons to expand and contract volume chambers of the cylinders with the rotation of the cylinder block, a biasing mechanism for biasing the swash plate in a direction to increase a tilting angle, a first control pin for driving the swash plate in a direction to reduce the tilting angle according to a first load pressure, and a second control pin for driving the swash plate in a direction to reduce the tilting angle according to a second load pressure. The first and second control pins are connected in series.

In at least one implementation, an engine oil circuit for a vehicle includes first and second oil circuits, and first and second oil pumps. The first oil circuit is communicated with at least one first engine component and the first oil pump is communicated with the first oil circuit to supply fluid flow in the first oil circuit at a first flow rate and a first pressure. The second oil circuit is communicated with at least one second engine component and may be segregated from the first oil circuit. The second oil pump is communicated with the second oil circuit to supply fluid flow in the second oil circuit at a second flow rate and a second pressure. At least one of the second flow rate or the second pressure is different than the first flow rate or the first pressure.

A heater for heating a conductive liquid includes a two-dimensional array of rod-like electrodes (22, 122, 322, 422, 522) extending parallel to one another, an electrical power supply having a plurality of poles, and power switches to connect different ones of the electrodes to different poles so that current flows between the poles through the liquid. The array desirably includes outer electrodes defining the boundary (24, 424) of the array and inner electrodes disposed within this boundary. The array may have regular or irregular spacings between the electrodes. The array can provide numerous different connection schemes to vary the electrical resistance between the poles and thus vary the heating rate. The array can be arranged to provide substantially equal currents through three poles of a three-phase power supply.

A method is provided for operating a wastewater pumping station of a wastewater pumping network. The pumping station includes a pump, that starts pumping if a level of a wastewater in a tank exceeds a first wastewater level, and the pump stops pumping if the level of the wastewater in the tank drops below a second level. The method includes determining a magnitude of a parameter (P.sub.sys, Q, n, ΔP, P.sub.electrical, cos φ, I) expressing the load of the wastewater pumping network. If it is determined that the magnitude of the parameter has passed a specified threshold, the pump is activated to start pumping in an energy optimization mode. A control unit is also provided for the wastewater pumping station of the wastewater pumping network, and a system is provided for centrally controlling a plurality of pumps of wastewater pumping stations in a wastewater pumping network.

According to one embodiment of the present invention, a system for pumping fluid is provided. According to this embodiment, a fluid pumping system comprises a fluid inlet pipe and a fluid outlet pipe. A plurality of pump units are disposed between the inlet and outlet pipes such that the pump units each pump fluid out of the inlet pipe and into the outlet pipe. The pump units each include at least one DC motor. A solar panel may be used to power the pump units.

According to one embodiment of the present invention, a system for pumping fluid is provided. According to this embodiment, a fluid pumping system comprises a fluid inlet pipe and a fluid outlet pipe. A plurality of pump units are disposed between the inlet and outlet pipes such that the pump units each pump fluid out of the inlet pipe and into the outlet pipe. The pump units each include at least one DC motor. A solar panel may be used to power the pump units.

A multistage compressor including: at least a first compressor main body and a second compressor main body configured to suck compressed gas discharged from the first compressor main body to discharge the compressed gas with higher pressure; a first driving source configured to drive the first compressor main body; a second driving source configured to drive the second compressor main body; an intermediate pipe configured to connect a discharge side of the first compressor main body and a suction side of the second compressor main body; a low-pressure side discharge piping system branched from the intermediate pipe; an on-off valve disposed in the low-pressure side discharge piping system and configured to switch permission and prohibition of a flow of compressed gas discharged from the first compressor main body; and a control unit configured to control driving of the first driving source and the second driving source.

A hydraulic system of vehicle transmission device is provided. A heat exchanger configured downstream is used to cool working oil discharged from a torque converter, and the working oil is supplied, as lubricating oil, to a lubricating system hydraulic circuit. On the other hand, excess oil flowing out of a regulator valve for regulating line pressure returns to an input side of an oil pump through a recycle oil path. A bypass oil path is disposed in a manner of branching from the recycle oil path and connecting to an input side of the heat exchanger. A control mechanism is disposed, and when hydraulic pressure at the side of the recycle oil path is higher than that at the side of the heat exchanger, the bypass oil path is opened to guide oil at the side of the recycle oil path to the input side of the heat exchanger.

Pressure measurement system (e.g., for an extracorporeal treatment system), method and pressure pod apparatus including a position sensor for use in repositioning a diaphragm that separates a liquid side cavity from a transducer side cavity (e.g., operatively connected to a pressure transducer); the liquid side cavity being in fluid communication with an inlet and an outlet.

A control method and system for a resonant linear compressor applied for controlling the capacity of a cooling system. The method includes: a) reading a reference operation power (P.sub.ref) of the motor of the compressor; b) measuring an operation current (i.sub.MED); c) measuring an operation voltage of a control module of the compressor; d) calculating an input power (P.sub.MED) of the motor as a function of the operation current (i.sub.MED) and of the operation voltage; e) comparing the input power (P.sub.MED) with the reference operation power (P.sub.ref); f) if the reference operation power (P.sub.ref) is higher than the input power (P.sub.MED), then increase an operation voltage of the compressor (UC); g) if the reference operation power (P.sub.ref) is lower than the input power (P.sub.MED), then decrease the operation voltage of the compressor (UC).