An excavator may include a lower traveling body; an upper turning body pivotally installed to the lower traveling body; an engine installed in the upper turning body; a main pump driven by the engine; and a processor and a memory that stores program instructions causing the processor to control a flow rate of hydraulic oil discharged by the main pump. The program instructions can cause the processor to, when a load of the engine increases, delay a response of the main pump 14 until an actual torque of the engine rises up to a level corresponding to the load of the engine.

A method of operating a system (16) for pumping a fluid, which system comprises a pump (17) comprising a suction side (18) and a discharge side (19); a motor (20) for driving the pump, which motor is drivingly connected to the pump via a shaft; a recirculation conduit (23) providing a fluid path for the fluid from the discharge side to the suction side of the pump; and a control valve controlling the flow of the fluid through the recirculation conduit, which method comprises the steps of: mapping a plurality of minimum torque diagrams for the pump, where each minimum torque diagram identifies the minimum allowable torque of the pump as a function of an operational parameter of the pump, e.g. the differential pressure over the pump; from said plurality of minimum torque diagrams, identifying the minimum torque diagram best representing the current operation of the pump; monitoring said operational parameter of the pump and, from the minimum torque diagram best representing the current operation of the pump, identifying a minimum allowable torque value corresponding to a monitored value of said operational parameter of the pump, e.g. a monitored differential pressure value; monitoring the torque of the pump and comparing a monitored torque value with the identified minimum allowable torque value; and regulating the control valve such that the monitored torque value does not fall below the minimum allowable torque value. A corresponding pumping system is also disclosed.

An electrical submersible well pump assembly has a SAW (surface acoustic wave) sensor on a motor shaft. A SAW electronic circuit mounts to the motor housing. The SAW electronic circuit has an antenna closely spaced to the SAW sensor for monitoring torque on the motor shaft. A controller at an upper end of the well supplies power to the motor. A motor gauge unit mounted to a lower end of the motor transmits signals to the controller. A signal line extends from the SAW electronic circuit to the motor gauge unit for transmitting signals from the SAW electronic circuit to the motor gauge unit, and from the motor gauge unit to the controller.

A method for conveying a fluid of a fluid circuit by means of an electric motor-powered fluid pump of a motor vehicle, in particular an oil pump, wherein by means of the fluid pump a fluid pressure of the fluid circuit is adjusted to a target pressure, and wherein an actual pressure of the fluid is determined without a pressure sensor.

A control system may include circuitry configured to: a deterioration level estimation unit configured to estimate deterioration levels of pumping devices based on information about driving forces of the pumping devices; a selection unit configured to select a pumping device from the pumping devices based on a comparison of the estimated deterioration levels estimated by the deterioration level estimation unit; and a pumping control unit configured to control the selected pumping device selected by the selection unit to pump fluid.

A method for conveying a fluid of a fluid circuit by means of an electric motor-powered fluid pump of a motor vehicle, in particular an oil pump, wherein by means of the fluid pump a fluid pressure of the fluid circuit is adjusted to a target pressure, and wherein an actual pressure of the fluid is determined without a pressure sensor.

A monitoring system may include a strain gauge, a position sensor, and a torque sensor. The strain gauge may measure strain in a chamber of the pressure pump and generate a strain signal representing the strain measurement. The position sensor may measure a position of a rotating member and generate a position signal representing the position measurement. The torque sensor may measure torque in a component of the pressure pump and generate a torque signal representing the torque measurement. The torque measurement may be used with the strain measurement and the position measurement to determine a condition of the pressure pump.

A rig management system is disclosed. The rig management system may be configured to receive information to be used to control shifting of a transmission to prevent cavitation during use of the hydraulic fracturing rig. The rig management system may be configured to determine a flow rate for a pump based on the information. The rig management system may be configured to determine an output torque of the transmission based on the flow rate. The rig management system may be configured to determine a transmission gear for the transmission based on the output torque and a fuel consumption map, wherein the fuel consumption map identifies a respective fuel consumption rate for different combinations of transmission gears and output torques. The rig management system may be configured to cause the transmission to shift into the transmission gear after determining the transmission gear.

Presented herein are systems and methods for attenuating flow ripple generated by a hydraulic pump. In certain aspects, a method and system for operating a hydraulic positive displacement pump according to a stabilized command profile are disclosed, such that flow ripple generated by operation of the pump according to the stabilized command profile is attenuated as compared to operation of the pump according to a corresponding nominal command profile. In other aspects, a pressure-balanced active buffer is disclosed that allow for at least partially cancelling flow ripple in a hydraulic circuit comprising a pump. In another aspect, a method for generating ripple maps for a pump is disclosed. Such ripple maps may be used, for example, to determine the stabilized command profile used to operate the pump, or may be used by the pressure-balanced active buffer to counteract ripple in the hydraulic circuit.

Presented herein are systems and methods for attenuating flow ripple generated by a hydraulic pump. In certain aspects, a method and system for operating a hydraulic positive displacement pump according to a stabilized command profile are disclosed, such that flow ripple generated by operation of the pump according to the stabilized command profile is attenuated as compared to operation of the pump according to a corresponding nominal command profile. In other aspects, a pressure-balanced active buffer is disclosed that allow for at least partially cancelling flow ripple in a hydraulic circuit comprising a pump. In another aspect, a method for generating ripple maps for a pump is disclosed. Such ripple maps may be used, for example, to determine the stabilized command profile used to operate the pump, or may be used by the pressure-balanced active buffer to counteract ripple in the hydraulic circuit.