Changing a cumulative pumping rate of multiple pump units by adjusting individual pumping rates of the pump units, wherein each temporary dip or spike of an individual pumping rate of one of the pump units is automatically offset by a predetermined temporary adjustment of an individual pumping rate of another one or more of the pump units to thereby reduce effects of the temporary dip or spike on the cumulative pumping rate of the pump units.

A radial piston hydraulic device distributed by pilot operated check valves includes a housing, a plurality of piston assemblies, a main shaft, the rotating shaft, first pilot operated check valves having a same number with the plurality of piston assemblies and one-to-one corresponding to the plurality of piston assemblies, and second pilot operated check valves having a same number with the plurality of piston assemblies and one-to-one corresponding to the plurality of piston assemblies. The housing includes a plurality of piston chambers, a rotating shaft chamber, a high-pressure oil passage, and a low-pressure oil passage. Each of the plurality of piston assemblies is slidable up and down in a corresponding piston chamber of the plurality of piston chambers. The main shaft is rotatably connected to the housing and is connected to the plurality of piston assemblies in a transmission way.

Variable displacement hydraulic unit comprising a displacement unit for setting/adjusting the position of an adjustment element in order to adjust the displacement volume of the hydraulic unit by means of an electronically driveable actuator. The actuator is electronically connected to an electronic control unit (ECU) and has a first electric conductive coil to position the adjustment element by the help of electro-magnetic forces. An electric energy harvesting device is located adjacent to the first coil of the actuator such that electric energy from power fluctuations in the first coil can be harvested inductively. The inductively harvested electric energy can be transmitted to an electric energy storage device.

The disclosure relates to a method for estimating a flow out of at least one fluid pump for injecting fluid in a well, comprising: —determining a calculation model for the flow rate of a pump exiting the at least one pump, said calculation model permitting the calculation of the flow rate in function of at least one calculation parameter (p, SPAM) related to the at least one fluid pump; then —providing at a plurality of measuring times (t.sub.m), a set of measurement values (P.sub.DH,m, P.sub.B,m, SPM.sub.DH,m, SPM.sub.B,m) representative of said at least one calculation parameter; then —estimating (86) the flow rate exiting the pump in function of the model and of said at least one calculation parameter.

The disclosure relates to a method for estimating a flow out of at least one fluid pump for injecting fluid in a well, comprising: —determining a calculation model for the flow rate of a pump exiting the at least one pump, said calculation model permitting the calculation of the flow rate in function of at least one calculation parameter (p, SPAM) related to the at least one fluid pump; then —providing at a plurality of measuring times (t.sub.m), a set of measurement values (P.sub.DH,m, P.sub.B,m, SPM.sub.DH,m, SPM.sub.B,m) representative of said at least one calculation parameter; then —estimating (86) the flow rate exiting the pump in function of the model and of said at least one calculation parameter.

A reciprocating pump assembly includes a fluid end section having a pressure chamber and a plunger bore that fluidly communicates with the pressure chamber. The reciprocating pump assembly includes a plunger configured to be held within the plunger bore of the fluid end section, and a linear actuator operatively connected to the plunger such that the linear actuator is configured to reciprocate the plunger within the plunger bore during operation of the reciprocating pump to thereby pump fluid through the fluid end section.

A variable flow hydraulic device having a plurality of cylinders for varying a flow of hydraulic fluid between a reservoir and a load, the device comprising: a housing having the plurality of cylinders with a plurality of corresponding pistons; an input port of the housing fluidly connected to each cylinder of the plurality of cylinders, the input port facilitating introduction of the hydraulic fluid to said each cylinder; a first output port of the housing connected to said each cylinder, the first output port facilitating the ejection of the hydraulic fluid from said each cylinder, the first output port configured for fluidly coupling said each cylinder to the load; a respective flow control valve for said each cylinder, and a fluid pressure sensing device coupled between downstream of the first output port and said respective flow control valve.

An apparatus comprising a synthetically commutated machine with one or more services, a prime mover coupled to the machine, a hydraulic circuit extending between the services and hydraulic loads to fluidically connect the services to the hydraulic loads such that groups of one or more services are fluidically connected to respective groups of one or more hydraulic loads. The apparatus configured such that the flow of hydraulic fluid to or from a group of services of the machine is controlled responsive to measuring a flow rate and/or pressure requirement of the hydraulic loads which are fluidically connected to the services, or receiving a demand signal indicative of a demanded pressure and/or flow rate based on a pressure and/or flow demand of hydraulic loads which are fluidically connected to the services.

An apparatus comprising a synthetically commutated machine with one or more services, a prime mover coupled to the machine, a hydraulic circuit extending between the services and hydraulic loads to fluidically connect the services to the hydraulic loads such that groups of one or more services are fluidically connected to respective groups of one or more hydraulic loads. The apparatus configured such that the flow of hydraulic fluid to or from a group of services of the machine is controlled responsive to measuring a flow rate and/or pressure requirement of the hydraulic loads which are fluidically connected to the services, or receiving a demand signal indicative of a demanded pressure and/or flow rate based on a pressure and/or flow demand of hydraulic loads which are fluidically connected to the services.

A variable flow hydraulic device having a plurality of cylinders for varying a flow of hydraulic fluid between a reservoir and a load, the device comprising: a housing having the plurality of cylinders with a plurality of corresponding pistons; an input port of the housing fluidly connected to each cylinder of the plurality of cylinders, the input port facilitating introduction of the hydraulic fluid to said each cylinder; a first output port of the housing connected to said each cylinder, the first output port facilitating the ejection of the hydraulic fluid from said each cylinder, the first output port configured for fluidly coupling said each cylinder to the load; a respective flow control valve for said each cylinder, and a fluid pressure sensing device coupled between downstream of the first output port and said respective flow control valve.