Abstract: An endcover for a turbine combustor adapted to support one or more combustor nozzles, includes a plate having one side which in use, faces a combustion chamber and an opposite side which, in use, faces away from the combustion chamber. At least one fuel cavity is formed in the plate; and a fuel restrictor insert is formed with at least one flow orifice located within the fuel cavity for supplying fuel to at least one combustor nozzle. The fuel restrictor insert is adjustable along a length dimension of the fuel cavity.

Abstract: The present application provides a dual gas fuel delivery system and a method of delivering two gas fuels. The dual gas fuel delivery system may include (a) a low energy gas delivery system comprising a low energy gas inlet, a gas split, a low energy gas primary manifold outlet, and a low energy gas secondary manifold outlet; (b) a high energy gas delivery system comprising a high energy gas inlet and a high energy gas primary manifold outlet; (c) a primary manifold; and (d) a secondary manifold, wherein the low energy gas primary manifold outlet and the high energy gas primary manifold outlet are coupled to the primary manifold, and wherein the low energy gas secondary manifold outlet is coupled to the secondary manifold.

Abstract: A fuel injection assembly for use in a turbine engine is provided. The fuel injection assembly includes a plurality of tube assemblies, wherein each of the tube assemblies includes an upstream portion and a downstream portion. Each tube assembly includes a plurality of tubes that extend from the upstream portion to the downstream portion or from the upstream portion through the downstream portion. At least one injection system is coupled to at least one tube assembly of the plurality of tube assemblies. The injection system includes a fluid supply member that extends from a fluid source to the downstream portion of the tube assembly. The fluid supply member includes a first end portion located in the downstream portion of the tube assembly, wherein the first end portion has at least one first opening for channeling fluid through the tube assembly to facilitate reducing a temperature therein.

Abstract: A fuel valve for a turbine engine, the valve has a fuel inlet connected to a supply of fuel and a purge inlet connected to a supply of purge air. Opening and closing apparatus within the valve selectively supplies air or fuel to a valve outlet. The opening and closing apparatus are movable in sequence from a first position where both the purge air and fuel to the outlet is disabled to a second position where the purge air is enabled and the fuel is disabled to a third position where the purge air is disabled and the fuel is enabled.

Abstract: A system includes a gas turbine engine having a combustor, a liquid fuel supply coupled to the combustor, and a water supply coupled to the liquid fuel supply. The water supply is configured to flow water through the liquid fuel supply while the liquid fuel supply is not in use to flow a liquid fuel.

Abstract: A system includes a plurality of interconnected mixing assemblies configured to mix a first fuel and water to generate a first mixture, and mix a second fuel and the water to generate a second mixture. The first and second fuel mixtures are configured to combust in a plurality of combustors of a gas turbine. The interconnected mixing assemblies include first and second fuel passages, a water passage, first and second mixers, first and second fuel valves, and first and second water valves disposed in an integrated housing. The first fuel valve has a first fuel flow coefficient between approximately 1.0 to 1.5, the second fuel valve has a second fuel flow coefficient between approximately 3.0 to 5.0, the first water valve has a first water flow coefficient between approximately 0.4 to 0.55, and the second water valve has a second water flow coefficient between approximately 3.5 to 5.0.

Abstract: An overspeed protection device includes at least one torque measurement unit supported by an output shaft coupled mechanically to a free turbine of a turbine engine and a signal processing unit able to transmit to a turbine engine regulating system a command to reduce a flow of fuel injected if it is detected that the torque has dropped below a first datum value. The signal processing unit is shaped to command a reduction of the flow if it is detected that the torque has dropped below a first datum value, the torque measurement used to trigger the reduction being taken during a rotation corresponding to a fraction of a revolution of the output shaft.

Abstract: A fuel system comprises a fuel actuation arrangement 28 operable to split a metered flow of fuel into at least a first stream and a second stream, a control unit 25 controlling the operation of the fuel actuation arrangement 28, and wherein the control unit 25 controls the operation of the fuel actuation arrangement 28 in response to the output of a temperature sensor 34 sensitive to a gas temperature downstream of the high pressure compressor 14 of an associated engine and the output of a gas sensor 24 sensitive to at least one parameter of the composition of a gas downstream of a combustor 15 of the engine.

Abstract: A method and device producing a setpoint signal representing a flow rate of fuel that a metering unit having a slide valve is to supply to a fuel injection system of a combustion chamber in a turbine engine, the position of the valve depending on the setpoint signal. The method: obtains a first signal representing a measurement as delivered by a flow meter of a flow rate of fuel injected into the chamber; evaluates a second signal representing the flow rate of fuel injected into the chamber based on a measurement of the position of the valve; estimates a third signal representative of the measurement delivered by the flow meter by applying a digital model of the flow meter to the second signal; and produces the setpoint signal by adding a compensation signal to the first signal, the compensation signal obtained by subtracting the third signal from the second signal.

Abstract: A gas turbine is operated using a varying blend of a first fuel, preferably natural gas, and a second fuel that is hydrogen. The hydrogen concentration is varied depending on operating conditions in order to reduce emissions of CO and NOx, and/or to mitigate LBO. The fuel mixture is varied using a controller based on a combination of factors in a modular operation concept to address different issues according to relevant load limitations. A method of operating a gas turbine according to this modular operational concept is also provided.

Abstract: A gas turbine engine fuel heat shield configured to shield fuel from high temperatures of surrounding turbine components to prevent coking of the fuel is disclosed. The gas turbine engine fuel heat shield may be formed from a generally elongated member having a first collar at a first end and a second collar at a second end opposite to the first end. One or more recesses may be positioned in an outer surface of the generally elongated member between the first and second collars. A sleeve is positioned around the generally elongated member and radially outward of the recess to form one or more sealed chambers. The sleeve may be sealed to prevent fuel from entering the recess and coking. Such design, therefore, prevents the formation of carbon particles from the fuel that could clog the fuel injectors.

Abstract: A combustor includes an end cap having an upstream surface axially separated from a downstream surface and a cap shield circumferentially surrounding the upstream and downstream surfaces. A first circuit of tubes extends from the upstream surface through the downstream surface. A first fuel plenum is in fluid communication with the first circuit of tubes. A second circuit of tubes extends from the upstream surface through the downstream surface. A second fuel plenum downstream from the first fuel plenum is in fluid communication with the second circuit of tubes. A method for supplying fuel to a combustor includes flowing a working fluid through tubes, flowing fuel or diluent from a first fuel plenum through a first circuit of tubes, and flowing fuel or diluent from a second fuel plenum through a second circuit of tubes, wherein the second fuel plenum is downstream from the first fuel plenum.

Abstract: A turbomachine including at least one thrust reverser and a device for actuating the thrust reverser, which includes at least one hydraulic engine supplied with pressurized fluid by a fuel circuit of the turbomachine, is disclosed.

Abstract: A fuel divider included in a fuel supply device of a gas turbine engine includes a movable member which is movable according to a fuel pressure at a fuel entrance, opens only a pilot port when the fuel pressure at the fuel entrance is lower than a first pressure, and opens both of the pilot port and the main port when the fuel pressure at the fuel entrance is higher than the first pressure. In addition, the fuel divider includes an adjusting means which adjusts a value of the first pressure in such a manner that it applies to the movable member a counter force in a direction opposite to a direction in which the movable member moves according to the fuel pressure at the fuel entrance, and adjusts the counter force.

Abstract: A system and method for supplementing fuel feed pressure and flow within an aircraft fuel system. The fuel system includes boost and override fuel pumps delivering fuel from the tanks to a fuel manifold, and a jettison fuel pump. The method includes the steps of: (a) sensing whether the aircraft engine is operating near maximum power; (b) upon sensing the condition, operating the jettison fuel pump in fluid interconnection with the override fuel pump to deliver fuel to the fuel manifold; and (c) upon sensing the cessation of the condition, deactivating the jettison fuel pump. The system includes a monitoring circuit signaling when the aircraft engine speed is greater than a predetermined threshold, and a fuel system control circuit operating a jettison fuel pump enable circuit portion in response to the signal while omitting other jettisoning operations. The jettison fuel pump consequently functions as an override fuel pump assist.

Abstract: A tunable fluid flow control system for controlling combustion dynamics in a combustor is disclosed. The control system includes a fuel supply path having an inlet portion, a first diverted portion, a second diverted portion, and an exit portion. A first diverted portion has a first length and a first diameter. A second diverted portion has a second length and a second diameter and spaced apart from the first diverted portion. The first and second diverted portions converge at a merging location. The exit portion is coupled to the merging location of the first and second diverted portions. At least one flow regulation device is coupled to the inlet portion and configured to divert fuel flow to the first and second diverted portions alternately to generate fuel flow perturbations at the merging location.

Abstract: A flow balancing valve for a multistage combustor includes a first pressure feedback line, a first burn line, and a first metering port fluidly connected to the first fuel injector. The flow balancing valve further includes a second pressure feedback line, a second burn line, and a second metering port fluidly connected to the second fuel injector. A metering land is located between and defines sizes of the first metering port and the second metering port. An increase in pressure differential between the first pressure feedback line and the second pressure feedback line causes a compensatory movement in the metering land to balance fuel flow for the first fuel injector and the second fuel injector.

Abstract: A fuel nozzle guide for a combustor of a turbine engine includes an annular base with a hub section, the hub section at least partially formed of a Cold Metal Transfer (CMT) weld and a method and system therefor.

Abstract: The present application provides a dual gas fuel delivery system and a method of delivering two gas fuels. The system may include (a) a low energy gas delivery system comprising a low energy gas inlet, a gas split, a low energy gas primary manifold outlet, and a low energy gas secondary manifold outlet; (b) a high energy gas delivery system comprising a high energy gas inlet and a high energy gas primary manifold outlet; (c) a primary manifold; and (d) a secondary manifold, wherein the low energy gas primary manifold outlet and the high energy gas primary manifold outlet are coupled to the primary manifold, wherein the low energy gas secondary manifold outlet is coupled to the secondary manifold, and wherein the low energy gas delivery system further comprises a primary low energy gas stop and pressure control valve between the gas split and the low energy gas primary manifold outlet.

Abstract: A method for operating a gas turbine (11) having a compressor (12), a turbine (14) and a combustor (13) with a pilot burner group (15a), a rich premix burner group (15b) and a lean premix burner group (15c), under changing composition of the incoming fuel gas (16), includes the steps of: continuously measuring, in real time, the composition of the fuel gas (16); and controlling the operation of the gas turbine (11) and the combustion of the burners (15a-c) by using the real time fuel gas composition measurements.

Abstract: A fuel supply assembly supplying a combustion chamber of a turbomachine with fuel and pressurizing the fuel, including: a first pump that pressurizes fuel drawn from tanks of an aircraft; a second pump that raises pressure beyond an outlet pressure of the first pump, and that provides constant fuel delivery, some of fuel leaving the second pump being sent to the combustion chamber via a direct circuit, the part of fuel not sent to the combustion chamber being recirculated, via a recirculation circuit, to upstream of the second pump; a hydraulic unit metering delivery to be injected into the combustion chamber of the turbomachine by a metering device on the direct circuit and at least one heat exchanger through which the fuel passes. The exchanger is positioned in a direct circuit downstream of the point at which the recirculation circuit branches off and upstream of the fuel metering device.

Abstract: A fuel system is described that comprises a pressure raising and shut-off valve (PRSOV), and a control valve arrangement operable to control a fuel pressure applied to a part of the PRSOV urging the PRSOV towards a closed position, wherein the control valve arrangement is supplied with fuel at a pressure controlled by a variable fluid pressure potentiometer network including a variable flow restrictor which is variable in response to changes in the position occupied by the PRSOV.

Abstract: According to one aspect, the subject application involves a method of controlling a transition of a gas turbine. The method includes receiving a request of the gas turbine to drive an increased load. The increased load is greater than a load being driven by the gas turbine when the request is received. The method further includes determining that a temperature of a fuel to be ignited within a combustor of the gas turbine is less than a target temperature of the fuel to be introduced into the combustor for driving the increased load. Responsive to this determination, the method also includes controlling introduction of an additive into the combustor of the gas turbine when the temperature of the fuel is less than the target temperature to establish a suitable Wobbe Index of a fuel combination to promote a substantially continuous transition of the gas turbine to drive the increased load, wherein the fuel combination includes the fuel and the additive.

Abstract: A fuel control arrangement includes an injector control valve, a fuel supply structure including a primary supply path, a secondary supply path, and a splitter valve configured to split fuel flow between the primary supply path and the secondary supply path to thereby regulate fuel supply. The fuel control arrangement also includes a fuel injector directly connected to the injector control valve. The splitter valve is configured to split fuel flow between the secondary path and the injector control valve in response to a fuel pressure indicative of fuel demand. Further, the splitter is provided distal to the fuel injector and the injector control valve, to operate under different environmental conditions from the injector and the injector control valve. The injector control valve is actuated by a fluid pressure system controlled by a solenoid.

Abstract: A fuel supply device of a gas turbine engine is provided. The fuel supply device includes a fuel divider which divides fuel supplied from a collecting fuel passage to feed the fuel to a pilot fuel passage and to a main fuel passage. The fuel divider includes a movable member which is movable according to fuel pressure at the fuel entrance and opens and closes pilot ports and main ports according to a distance of the movement of the movable member. When the fuel pressure at the fuel entrance is not higher than a predetermined value, the fuel is supplied only to the pilot fuel passage, while when the fuel pressure at the fuel entrance is higher than the predetermined value, the fuel is supplied to the pilot fuel passage and to the main fuel passage.

Abstract: A unitary distributor is disclosed, comprising at least one main flow passage located within a distributor ring body, the main flow passage having an arcuate portion oriented in a circumferential direction around a distributor axis. Exemplary embodiments of a unitary distributor having an annular ring located at the axially forward end of the distributor ring body are disclosed. A fuel distributor is disclosed, comprising a fuel conduit and a distributor wherein the fuel distributor has a unitary construction.

Abstract: A fuel system comprising a liquid fuel tank, an engine, and a coalescing filter adapted to separate water from fuel, the filter having an inlet fluidically connected to the fuel tank, a first outlet fluidically connected to a fuel feed system for the engine, and a second outlet fluidically connected to the fuel tank, wherein the coalescing filter is adapted to discharge fuel filtrate from the second outlet and filtrand from the first outlet. Also, a method of removing water or ice from a fuel tank, the method comprising directing a flow of fuel from a fuel tank to a coalescing filter adapted to separate water from fuel, discharging filtrand from a first outlet of the coalescing filter to a fuel feed system for consumption by an engine, and discharging fuel filtrate from a second outlet of the coalescing filter and returning the fuel filtrate to the fuel tank.

Abstract: An example turbomachine assembly includes a first combustor configured to combust fuel and compressed air and a second combustor configured to combust fuel and compressed air. Flow moves through the first combustor in a first direction and flow moves though the second combustor in a second direction different than the first direction. The first combustor is axially spaced from the second combustor.

Abstract: A dry low NOx (DLN) fuel nozzle of a fuel system is provided and includes one or more downstream orifices formed to define a first fluid path along which fluid is directed to flow, an upstream orifice, located upstream from the one or more downstream orifices, formed to define a second fluid path along which the fluid is directed to flow and connecting passages disposed to fluidly couple the first and second fluid paths of the downstream and upstream orifices, respectively, to one another. At least one of a radial size and an axial location of the upstream orifice is set to cooperatively detune an acoustic impedance of the fuel system.

Abstract: A process is disclosed for monitoring the formation of deposits of solid particles in a fuel line having a valve. A measure for the deposits of solid particles in the fuel line is determined by determining the degree of opening of the valve passage and the quantity of fuel flowing through the valve, and by comparing them with a previously determined control value which characterizes the deposit-free line. Also disclosed is a device for monitoring the formation of deposits of solid particles in a fuel line having a valve, the device having a measurement system for determining the current fuel flow and a measurement system for determining the current valve position, as well as an evaluation system connected to the measurement systems. Also disclosed is a combustion chamber comprising a device and operated by a process according to the invention, and a gas turbine with said combustion chamber.

Abstract: A fuel delivery and control system is provided including a dual pump fluid circuit configuration comprising a fixed positive displacement pump sized to supply the main engine burn flow ranging from above windmill through cruise, a positive displacement actuation pump including a variable pressure regulator, wherein the actuation pump is sized to supply fluid to engine actuators, valves and other hydraulically operated engine components and a pump flow sharing system interconnecting the two pumps. The combined flow from the two pumps is sufficient to meet the engine flow demand for windmill relight and maximum flow conditions. During cruise or normal operating conditions, the pumps operate in completely isolated flow circuits, minimizing recirculation and therefore heat input into the fuel supply system.

Abstract: A controller for a turbine power plant that is operable to identify a failure condition and measure a shutoff valve performance.

Abstract: A fuel feed circuit for an aeroengine, the circuit including a high-pressure pumping system including first and second positive displacement pumps, a hydraulic actuator, and a fuel metering unit. As a function of a position of a slide of the actuator, a feed orifice of the actuator may be connected to a high-pressure delivery orifice connected to an outlet of the second pump, or to a low-pressure delivery orifice connected to a low-pressure feed line. The fuel metering unit includes through sections, one of these through sections being connected to an outlet of the high-pressure pumping system and the other through section being connected to an outlet of the high-pressure pumping system and leading to a high-pressure pilot chamber of the hydraulic actuator.

Abstract: A fuel feed circuit for an aeroengine, the circuit including a high-pressure pumping system for delivering fuel at high pressure to combustion chamber injectors, the high-pressure pumping system including first and second positive displacement gear pumps driven simultaneously by the engine. A hydraulic switch member is interposed between respective outlets of the pumps, which makes it possible, in one state, to combine outlet flows from the two pumps to deliver fuel at high pressure to the combustion chamber injectors, and in another state, to discharge some or all of outlet flow from the first pump to a low-pressure feed line, an electrical control member serving to cause the hydraulic switch member to pass from one state to the other.

Abstract: A system and method to reduce the gas fuel supply pressure requirements of a gas turbine, which results in an increased operability range and a reduction in gas turbine trips. According to the method, the gas turbine is allowed to start and operate at supply pressures determined as a function of ambient conditions and gas turbine compressor pressure ratio. This increases the operability window, and reduces or eliminates the need for gas fuel compressors.

Abstract: A turbine engine fuel supply system includes a priority flow line, a plurality of secondary fuel loads, a fluid-powered metering pump, a mechanically-driven fuel pump, and an electric machine. The fluid-powered metering pump, upon receiving fuel at its fuel inlet, rotates at a rotational speed, discharges the fuel from its fuel outlet at a flow rate dependent on the rotational speed, and supplies a first drive torque. The mechanically-driven fuel pump receives a second drive torque and, in response, draws fuel into its fuel inlet and discharges the fuel from its outlet to the fluid-powered metering pump fuel inlet to drive the fluid-powered metering fuel pump. The electric machine receives the first drive torque from the fluid-powered metering pump and generates electrical power.

Abstract: A combustor nozzle includes a center body and a shroud circumferentially surrounding at least a portion of the center body to define a passage between the center body and the shroud. A guide between the center body and the shroud can pivot with respect to the center body. A method for supplying fuel to a combustor includes flowing a working fluid through a nozzle at a mass flow rate and flowing a fuel through the nozzle. The method further includes sensing a flame holding event inside the nozzle and pivoting a guide inside the nozzle to increase the mass flow rate of the working fluid flowing through the nozzle.

Abstract: A fuel conveying member of a gas turbine engine is described and includes a fuel manifold defining an annular fuel flow passage through a body of the fuel manifold. A plurality of fuel nozzles extend from the manifold in fluid flow communication with the annular fuel flow passage. The fuel manifold includes integral attachment lugs thereon for mounting the fuel manifold within the gas turbine engine. The attachment lugs are adapted to receive pins therein and provide a mounting mechanism which allows for thermal expansion of the fuel manifold relative to a surrounding support structure to which the fuel manifold is mounted via the attachment lugs.

Abstract: A fuel flow system for a gas turbine includes a first pump, a main fuel flow path and a second pump. The first pump is connected to an actuator and a metering valve. The main fuel flow path is formed between the first pump and the metering valve. The second pump is connected to the main fuel flow path and supplements the fuel flow from the first pump under certain conditions. The second pump and first pump are in parallel.

Abstract: A fuel supply system includes a fuel metering pump and a servo-flow pump that are used to supply fuel to one or more fuel manifolds and one or more fluid-operated actuators, respectively. The fuel metering pump and the servo-flow pump are driven by the same electric motor(s).

Abstract: Various embodiments of a fuel-control system for regulating the administration of a first fuel to a fuel consuming device are disclosed. In one aspect, the fuel-control system includes a system-controlling device adapted to consume a primary source of electrical power. The system controlling device is also adapted to consume a secondary source of electrical power, with the secondary source produced by noncombustibly consuming a second fuel.

Abstract: An aircraft fuel pumping arrangement comprises a first fuel pump, an electrically powered motor operable to drive the first fuel pump to deliver fuel to an outlet, a second fuel pump, a gas driven turbine operable to drive the second fuel pump to deliver fuel to the outlet, and a controller operable to control the operation of the gas driven turbine to determine the rate at which the second fuel pump is driven.

Abstract: A gas turbine engine fuel system includes a fuel tank for storing fuel, a heat exchanger through which the fuel from the fuel tank can pass, a fuel pump located downstream from the heat exchanger for pumping the fuel, a fuel metering unit for metering the fuel pumped by the fuel pump, an additive tank for storing a fuel additive, an additive delivery subsystem for mixing the fuel additive with the fuel at or before the heat exchanger to generate a fuel and fuel additive mixture, and a combustor located downstream of the fuel metering unit where the fuel and fuel additive mixture is delivered for combustion. The fuel additive comprises a fuel stabilizer for reducing fuel coking.

Abstract: A fuel system for a turbine engine is provided. The fuel system includes a positive displacement pump driven by an electric motor. The pump is rotated in a first direction to deliver fuel to the turbine engine, and a second direction for evacuating fuel from the turbine engine. A shut-off check valve is open in a first direction in response to a first differential pressure created by the pump in the first direction. The shut-off check valve is biased to a closed position when the pump is rotating in the second direction. An ecology check valve is biased to a closed position in the first direction and open in the second direction in response to a second differential pressure created by the pump. The check valves open and close automatically in response to the pressures generated by the positive displacement pump in each of the first and second rotational directions. In this manner, simple, reliable valves are utilized to regulate the flow of fuel in the fuel system.

Abstract: A power-generation plant 10 including a gas turbine 11; a fuel-gas cooler 13; and an extraction line 24 that guides the fuel gas extracted from an intermediate stage of a fuel-gas compressor 12 to the fuel-gas cooler 13; a first level detector 61 that detects whether a level of the coolant accumulated at a bottom portion of the fuel-gas cooler 13 has reached a predetermined level; and a controller that stops the gas turbine 11 on the basis of a detection signal sent from the first level detector 61 and that outputs a command signal for stopping a coolant pump 53 that supplies the coolant to the spray nozzles 44 and 45.

Abstract: A system includes a fuel nozzle. The fuel nozzle includes a hub having an axis, a shroud disposed about the hub, an airflow path between the hub and the shroud, multiple vanes extending between the hub and the shroud, and a first fuel path leading to multiple first fuel outlets disposed on the multiple vanes. The fuel nozzle also includes a second fuel path leading to multiple second fuel outlets disposed on at least one of the hub and/or the shroud, wherein the multiple second fuel outlets are disposed at an axial distance upstream from a downstream end of the hub.

Abstract: A method of assembling a fuel delivery system is provided. The method includes providing a base that includes a surface, a receptacle extending into the base from the surface along a longitudinal axis, and a plurality of channels extending into the base from the receptacle. Each of the plurality of channels includes an inlet end and an outlet end, and each of the plurality of channels intersects the receptacle at the outlet end, wherein the receptacle and the plurality of channels are formed integrally within the base such that the plurality of outlet ends are spaced axially from one another. The method further includes securing a fuel nozzle within the receptacle, the fuel nozzle including a plurality of separate flow paths, wherein each of the plurality of channels is in flow communication with one of the plurality of separate flow paths.

Abstract: A combustor is provided and includes a center body having a tubular inner wall, a cartridge disposed within the tubular inner wall to define an outer annular space between an outer surface thereof and the tubular inner wall and an inner annular space having an open end and a closed end opposite the open end and an insert disposed within the outer annular space to envelop the cartridge proximate to the open end, the insert including a body having a tubular forward portion and a partially tubular aft portion, the partially tubular aft portion thereby forming a recessed track having a longitudinal axis substantially aligned with a longitudinal axis of the outer annular space.

Abstract: A fuel line system for a gas turbine and a method for purging the same is provided. Parts of the line system may be purged using a comparatively low quantity of purging medium.

Abstract: A fuel flowmeter for being fed by a pump including an inlet and an outlet, including: a metering valve including an inlet and an outlet, and arranged downstream from the outlet of the pump; a return circuit connecting the inlet of the metering valve to the inlet of the pump; and a pressure regulator device including: a movable valve member to close and open the return circuit, a pressure difference detection surface fastened to the valve member and axially separating a first chamber in communication with the inlet of the metering valve from a second chamber in communication with the outlet from the metering valve, a piston axially separating the second chamber from a third chamber connected to the outlet of the metering valve, and a channel putting the second chamber in communication with the third chamber.