Abstract: The invention relates to an injector for injecting fuel that is at high pressure into the combustion chambers of an internal combustion engine. A control part (4) which is movable up and down by actuator actuation is received in a bore (3) in the housing (2) of the injector (1). By means of the actuator, the control part (4) is movable into a position that enables the fuel delivery into a nozzle inlet (10, 11). The valve chamber (8, 38) in the housing (2) of the injector (1) can be opened and closed during the injection phases (41, 42) by control edges (36, 37) toward the control part, while the pressure relief of the injection system (11, 12, 34) is effected via slide portions (13, 21) disposed on the control part (4).

Abstract: A variable pressure fuel injection system and multi-flow rate injector is provided which produces multiple fuel injection flow rates from a common source of pressurized fuel to enable reductions in emissions, combustion noise and particulates while improving fuel consumption. The present invention includes inner and outer needle valve elements biased into respective closed positions against respective valve seats for controlling the flow through corresponding sets of injection orifices. The movement of each valve is controlled by an injection control valve controlling the drain flow of control fuel from respective control volumes positioned at outer ends of the valve elements. Valve element bias spring preloads along with control flow orifices and needle valve element surface areas are selected to cause, for example, single valve operation at low fuel supply pressure and dual valve operation at high supply pressure.

Abstract: A piezoelectric actuated fuel injector is provided for use in conjunction with an internal combustion engine. The fuel injector includes a piezoelectric actuator for actuating an injector valve, and a hydraulic assembly for interfacing between the piezoelectric actuator and the injector valve, where the injector valve axially separates from a discharge outlet in response to longitudinal expansion of the piezoelectric actuator, thereby allowing fuel flow from the fuel injector.

Abstract: The invention relates to a metering valve for controlling the delivery of fuel from a high-pressure fuel line (1) to an injection nozzle (6) of an internal combustion engine, having one connection for the high-pressure fuel line (2), one connection for the injection nozzle (6), and one connection for a leak fuel line (13).

Abstract: A closed needle injector assembly and method are provided which effectively extending injection duration and improving fueling accuracy at part load conditions, providing a low quantity detached pilot injection at all operating conditions and controlling the duration of, and dwell time between, the pilot injection and one or more higher flow rate primary injections independent of fuel injection pressure. The closed needle injector assembly includes first and second needle valve elements, respective control volumes and a single injection control valve to control the movement of the needle valve elements. A sequencing device is mounted on the injector to permit movement of only the inner needle valve element to define a low fuel injection rate event and permit selectively, controlled movement of both the inner and outer needle valve elements to open positions to define a subsequent primary fuel injection event.

Abstract: A fuel injection device is so constructed that fuel fed from a pressure storage chamber to a valve housing (11) with a nozzle (14) is led to a needle valve back pressure chamber (16) through a groove (21) provided on the peripheral surface of a needle valve (17); a fuel pressure in the back pressure chamber (16) is controlled by opening and closing a pressure regulating port (13) provided in the valve housing by a pilot valve (38) so as to move the needle valve, whereby the nozzle is opened and closed. The pressure regulating port is opened and closed by a drive control of the pilot valve with a valve drive unit by means of elongation and contraction of the magnetostrictive rods attributable by the action of an external magnetic field. The magnetostrictive rods, consisting of first and second magnetostrictive rods (34 and 35), are axially arranged side by side in parallel to the pilot valve.

Abstract: The fuel injection device has a fuel pump for each cylinder of the engine, which fuel pump has a pump piston that is driven into a stroke motion by the engine and delimits a pump working chamber, which is supplied with fuel from a fuel tank and is connected to a fuel injection valve, which has an injection valve member that controls at least one injection opening and can be moved by the pressure generated in the pump working chamber in an opening direction counter to a closing force. A first electrically controlled control valve controls a connection of the pump working chamber to a discharge chamber, and a second electrically controlled control valve controls the pressure prevailing in a control pressure chamber of the fuel injection valve, which pressure acts at least indirectly on the injection valve member in the closing direction.

Abstract: An internal combustion engine fuel injector has a casing defining a nozzle; and a shutter pin having an axis, and housed in axially sliding manner inside the casing to close the nozzle by virtue of a control rod. The pin and the control rod are connected by a connecting device, which has an axial seat carried by the pin, and a head interposed between the axial seat and the control rod, and which engages the axial seat to transmit to the pin a resultant of forces directed solely along the pin axis.

Abstract: A fuel injector for use in an injector arrangement includes a fuel pump having a pump chamber and a spill valve controlling communication between pump chamber and a low pressure reservoir. The injector includes a valve needle which is engageable with a valve needle seating, a control chamber arranged such that the fuel pressure therein urges the valve needle towards the valve needle seating. A control valve is provided for controlling the fuel pressure within the control chamber. An actuator arrangement is arranged to control the operation of the control valve such that, when the actuator arrangement is de-energised, the control valve permits communication between the control chamber and the low pressure reservoir.

Abstract: An injection valve member for the closing and opening of injection orifices of a valve seat element is installed longitudinally adjustably in a central housing bore of a fuel injection valve. The opening and closing movement sequence of the injection valve member is controlled by a control device. A control piston operatively connected to the injection valve member is loaded, on the one hand, by the fuel system pressure prevailing in a high-pressure zone and, on the other hand, by the fuel control pressure in a control space. The high-pressure zone includes the central housing bore which is closed off sealingly by a control body fixed to the housing. The control space is arranged between the control body and a piston end face and is at least temporarily delimited radially by a control sleeve which is moveable transversely to the longitudinal axis of the housing.

Abstract: The invention relates to a fuel injection apparatus for an internal combustion engine, having an injection valve (14) that protrudes into the combustion chamber of the engine. This valve communicates with a valve chamber (6.1), in that a control part (6) closes and opens inlet bores (5, 8) for fuel that is at high pressure. The control part (6) is actuatable by means of a hydraulic-mechanical booster (18, 19, 20, 21). The pump part (P), valve part (V) and nozzle part (D) of the fuel injection apparatus (1) are disposed in a vertical arrangement, hydraulically in line with one another in terms of the fuel flow.

Abstract: A control valve configuration is described which is used in a fuel injector for internal combustion engine. The control valve contains a valve body that can be displaced axially in a valve chamber by an actuating device and is formed of two rigidly connected sections. A first section of the valve body forms a seat valve between the valve inlet and valve outlet in a first section of the valve chamber. The seat valve is closed in a rest position of the valve body and is opened in a working position of the valve body. A second section of the valve body and a second section of the valve chamber form a slide valve which, in the rest position of the valve body, produces a fluidic connection between the valve outlet and a return opening and blocks the fluidic connection between the seat valve and the valve outlets and which closes the return opening and then starts to produce a fluidic connection between the seat valve and the valve outlet only after it leaves the rest position.

Abstract: The invention relates to an injector for injecting fuel, which is under extremely high pressure, into the combustion chambers of an internal combustion engine. A valve body is provided, which opens and closes a valve chamber received in the injector housing, and an inlet leads from the valve body to the injection nozzle. For actuating the valve body, a control chamber of the injector housing is pressure-relieved by means of a control element. The inlet originating at the high-pressure collection chamber (common rail), extends centrally through the valve body, which is received movably in the injector housing.

Abstract: The fuel injection valve is in particular a component of a reservoir fuel injection system and has a valve body and an electric control valve that controls the pressure which prevails in a control pressure chamber and acts at least indirectly on an injection valve member in its closing direction, wherein the control pressure chamber is connected to a high-pressure fuel source and can be connected by the control valve to a discharge chamber in order to open at least one injection opening. The control pressure chamber is embodied in a sleeve-shaped section of an insert piece inserted into the valve body and is connected to an inlet bore in the valve body by means of an annular chamber encompassing the section and a connecting bore provided in the valve body. The connecting bore intersects the inlet bore at an obtuse angle (&agr;) in a region that is offset from the annular chamber in the direction of the longitudinal axis of the valve body.

Abstract: The invention relates to an injector for injecting fuel that is at very high pressure, which is present at the injector in a common-rail inlet. The fuel acts on a control part, which is actuatable via a fuel volume contained in the control chamber. An inlet and an outlet of the control chamber are each provided with spring elements; the control chamber can be pressure-relieved via a valve element actuatable by means of an actuator. The control part in the injector housing is guided in two guide portions.

Abstract: A fuel injector comprising a valve needle slidable within a first bore, a surface associated with the valve needle being exposed to the fuel pressure within a first control chamber and movement of the valve needle away from the valve needle seating being limited by a moveable stop member. The stop member has a surface exposed to fuel pressure within a second control chamber. The fuel injector also includes a control valve arrangement for controlling the fuel pressure within the first and second control chambers to control movement of the valve needle and the stop member. The invention also relates to a fuel injector in which the control valve arrangement is arranged to permit the rate of valve needle movement away from the valve needle seating to be varied, in use.

Abstract: A common rail injector, having a nozzle body that is secured with the aid of a lock nut to a retaining body having a fuel inlet, which communicates with a central high-pressure fuel reservoir outside the injector and with a pressure chamber inside the injector. From the pressure chamber, as a function of the position of a control valve, fuel subjected to high pressure is injected. The control valve assures that a nozzle needle, which can reciprocate in a longitudinal bore of the injector axially counter to the prestressing force of a nozzle spring that is received in a nozzle spring chamber, lifts from a seat when the pressure in the pressure chamber is greater than the pressure in a control chamber that communicates with the fuel inlet via an inlet throttle. To make higher nozzle needle speeds possible, the control chamber is integrated with the nozzle body.

Abstract: The invention relates to an injector for injecting fuel into combustion chambers of an internal combustion engine. The injector includes an injector housing (2), in which a control chamber (20) is embodied that can be subjected to a control volume via an inlet throttle (21). The control chamber (20) can be pressure-relieved to an actuator-actuatable control element (10), as a result of which a control part (3) is movable vertically in the injector housing (2). The control part (3) and the nozzle needle (22) are embodied integrally.

Abstract: An improved closed nozzle injector assembly for injecting high pressure fuel into the combustion chamber of an engine is provided which includes a first needle valve element associated with a first set of injector orifices, a first needle valve control device for controlling the opening and closing of the first needle valve, a second needle valve associated with a second set of injector orifices and a second needle valve control device for controlling the opening and closing of the second needle valve. Each needle valve control device includes a control volume positioned at one end of the respective needle valve, a control volume charge circuit for supplying high pressure fuel to the respective control volume and the respective injection control valve for controlling the flow of high pressure fuel from the respective control volume to a low pressure drain thereby controlling the movement of the respective needle valve.

Abstract: A fuel injector comprising a valve needle, engagable with the seating to control fuel flow through a fuel outlet, the valve needle having a thrust surface oriented such that the application of fuel under pressure thereto applies a force to the valve needle urging the valve needle away from the seating. The fuel injector also comprises a valve member for controlling fuel pressure within a control chamber and a piston member slidable within a bore and defining, with the bore, the control chamber. The piston member is exposed to fuel pressure within the control chamber and is arranged to transmit a force applied by the fuel pressure to the valve needle. The piston member has an effective surface area exposed to the fuel pressure which is greater than that of the thrust surface so as to urge the valve needle towards the seating.

Abstract: An injection for injecting fuel under high pressure in a combustion chamber of an internal combustion engine has a control chamber, a valve body which is pressure loaded from the control chamber, a further control chamber, a nozzle needle which is pressure loaded from the further control chamber, a nozzle inlet, a nozzle chamber provided for the nozzle needle and loaded from the nozzle inlet, a valve body formed as a 3/2-way valve for pressure controlling the injector, a 2/2-way valve for stroke controlling of the injector at a leakage oil side, and a common controller, the valves being controllable either by the common controller or separately from one another.

Abstract: A fuel injector for injecting pressure fuel in a combustion chamber of an internal combustion engine has an injector housing, an inlet connectable with a high pressure collecting chamber, a nozzle inlet line, a 2/2-way valve for opening and closing the nozzle inlet line, a control chamber in which a pressure change occurs, at least one first ball valve positioned at a side of the control chamber, at least one second ball valve positioned at a side of the inlet, and a guide element movable in the housing, the first and second ball valve being positioned opposite to one another and associated with the movable guide element.

Abstract: An oil activated fuel injector which provides a pilot quantity of fuel prior to the main fuel injection event. The oil activated fuel injector includes a throttle which provides fluid communication between the high pressure chamber and a fuel bore which leads to the nozzle of the oil activated fuel injector. The pilot quantity of fuel flows through the throttle and into the fuel bore during a pre stroke of the plunger. The oil activated fuel injector reduces engine emissions and noise, and eliminates the need for additional working fluid to be provided therein in order to provide a pilot quantity of fuel.

Abstract: A fuel injector for an internal combustion engine has an injector housing having a pressure releasable control chamber for a vertical stroke movement and an annular chamber, an injector body closeable by the annular chamber, an inlet connectable to a high pressure collecting chamber and connected to and emptying into the annular chamber, an injection nozzle having a nozzle inlet and a nozzle chamber, with the nozzle inlet opened or closed by a sealing surface, a hydraulic spring associated with the injector body and including a control element impinged with high pressure via a volume of the hydraulic spring and via the inlet.

Abstract: An injector for injection a fuel under high pressure into a combustion chamber of an internal combustion engine, the injector has an injector housing, a control chamber, a primary-side inlet to the control chamber, a control valve which controls the primary-side inlet to the control chamber, a pressure multiplier movable in the injector housing, the pressure multiplier being formed as a two-part piston arrangement.

Abstract: An injector for injecting fuel, which is at high pressure, into the combustion chamber of an internal combustion engine includes valve body movably received in an injector housing, and a slide region is embodied on it. The valve body further includes a seat diameter, which cooperates with a seat face embodied on the housing and by way of which a nozzle inlet to a nozzle chamber of an injection nozzle can be opened and closed. The valve body is embodied as a 3/3-way control valve, by way of whose slide region a control chamber that varies the stroke of a nozzle needle can be controlled.

Abstract: A fuel injector comprising a valve needle, engagable with the seating to control fuel flow through a fuel outlet, the valve needle having a thrust surface oriented such that the application of fuel under pressure thereto applies a force to the valve needle urging the valve needle away from the seating. The fuel injector also comprises a valve member for controlling fuel pressure within a control chamber and a piston member slidable within a bore and defining, with the bore, the control chamber. The piston member is exposed to fuel pressure within the control chamber and is arranged to transmit a force applied by the fuel pressure to the valve needle. The piston member has an effective surface area exposed to the fuel pressure which is greater than that of the thrust surface so as to urge the valve needle towards the seating.

Abstract: A hydraulically actuated fuel injection system according to the present invention comprises at least one hydraulically actuated fuel injector that includes an injector body that defines a fuel pressurization chamber. A pumping element having a stepped top is movably mounted in a pumping bore defined by the injector body, wherein the pumping element defines at least one internal passageway. The pumping element is movable a distance between a first position and a second position. A spill passage defined by the injector body is open to the fuel pressurization chamber via the at least one internal passageway over a portion of the distance.

Abstract: A fuel injector includes an injector body that defines a nozzle outlet. A needle valve member is mounted in the injector body and moveable a lift distance between an open position in which the nozzle outlet is open, and a closed position in which the nozzle outlet is blocked. A piezoelectric actuator is mounted in the injector body and is moveable a piezo distance between an off position and an on position. A coupling linkage interconnects the needle valve member to the piezoelectric actuator such that a movement of the piezoelectric actuator is multiplied into a larger movement of the needle valve member.

Abstract: An injector for injecting fuel in a combustion chamber of an internal combustion engine has a housing provided with a housing opening, a control valve body movable in the opening of the housing, a ring chamber which encloses the control valve body, an inlet connectable with a high pressure collecting chamber and opening into the ring chamber, a nozzle inlet arranged so that during the movement of the control valve body the nozzle inlet is connected with the inlet or separated from the latter, and 2/2-way control valves arranged inside the housing in series so that one of the 2/2-way control valves is force-equalized in an open condition.

Abstract: A fuel injector is provided which has an improved structure capable of adjusting fuel jet characteristics such as the quantity of fuel to be injected to an engine and a fuel injection time lag after the fuel injector is assembled. The fuel injector includes an air gap adjusting screw and a spring pressure adjusting screw. The air gap adjusting screw serves to change an air gap between a stator and an armature of a solenoid valve to adjust the quantity of fuel to a target one. The spring pressure adjusting screw serves to change a spring pressure urging a valve in a spray hole-closing direction to regulate a spray hole open duration, thereby adjusting the fuel injection time lag or the quantity of fuel.

Abstract: An injector for injecting fuel in a combustion chamber of an internal combustion engine has an injector housing, 2/2-way double valves received in the injector housing and coupled with one another for joint vertical movements, a hydraulic multiplier associated with the 2/2-way-control valves, a nozzle chamber which surrounds a nozzle needle and supplied with high pressure fuel by the hydraulic multiplier, the 2/2-way control valves in the housing being turned relative to one another and have valve bodies and guiding elements which surround the valve bodies.

Abstract: A fuel injector for use in an injector arrangement including a fuel pump having a pump chamber and a spill valve arrangement including a spill valve member which is engageable with a valve seating to control communication between the pump chamber and a low pressure drain. The fuel injector further comprises a valve needle which is engageable with a valve needle seating, a control chamber arranged such that the fuel pressure therein urges the valve needle towards its seating, a control valve arrangement, including a control valve member, for controlling the fuel pressure within the chamber, and an actuator arrangement for controlling movement of the spill valve member and the control valve member. The actuator arrangement comprises a double pole actuator having a first armature which is movable with the spill valve member and a single pole actuator having a second armature which is movable with the control valve member.

Abstract: A fuel injection valve for intermittent injection of fuel into the combustion chamber of a diesel or other form of internal combustion engine. The valve achieves a shorter than usual injection valve member, while avoiding valve member oscillation but retaining precise closing by implementing a solenoid controlled piston that controls movement of the valve. The piston in turn is acted upon by fuel system pressure from a high pressure feed line and from a control chamber, alternatively, depending upon the position of an actuating element. The control piston has an annular land that faces the control chamber and the piston is connected to the high pressure feed line through a tight sliding fit in a piston guide bore establishing a leak gap. A relief chamber is formed between the outlet side of the gap and the land. When the injection valve is open, the land reduces fuel flow from the relief chamber into the control chamber.

Abstract: A fuel injection system for internal combustion engines in which the control of the fuel injection valve member is controlled by controlling the pressure of a control chamber. The control chamber is either relieved by a 3/2-way control valve or made to communicate with a high-pressure fuel source. The control valve is designed such that the control valve has a valve body, which on both sides carries a valve sealing face, which cooperate with a first valve seat and second valve seat, respectively, and control the inflow of high pressure into or outflow thereof out of the control chamber. To vary the dynamics of the control events, the valve body, upstream of the second valve sealing face, has a throttle gap, and downstream of the first valve sealing face the valve body has a collar, between the collar and the throttle gap a pressure conduit leads away to the control valve, the inflow and outflow to and from which is thus varied.

Abstract: A piezoelectrically actuable fuel injector comprising an accumulator volume within which a piezoelectric stack is arranged, the accumulator volume being arranged to receive fuel from a source of pressurized fuel, in use. The piezoelectric stack carrying an end member which engages a surface associated with a piston member so as to apply a retracting force to the piston member upon a reduction in the axial length of the piezoelectric stack, the piston member being operable to control fuel pressure within a control chamber. A volume is defined between the end member and the surface associated with the piston member. The volume is provided with a vent arrangement to permit fuel within the volume to flow to a low pressure drain.

Abstract: An injection nozzle of a pressure-controlled fuel injection system has a control chamber for exerting pressure on a nozzle needle. The control chamber is connectable to a pressure reservoir via a pressure line that includes a 2/2-way valve. On the end of the nozzle needle that can be acted upon by pressure and is remote from the injection opening, a bore is embodied, by way of which the control chamber of the injection nozzle can be made to communicate with a leakage line as a function of the stroke of nozzle needle.

Abstract: The invention relates to an injector with a valve chamber which is contained in an injector housing and can be loaded by way of an inlet from the high-pressure accumulation chamber. This valve chamber loads a nozzle inlet to an injection nozzle by means of a control element that can be moved in the injector housing upon the pressure relief of a control chamber. On the control element, which is embodied of one part or multiple parts, a control surface is disposed in the pressure relief region of the nozzle inlet.

Abstract: A fuel injector is provided which is designed to suppress unwanted vibrations of a nozzle needle-actuating piston, thereby avoiding the injection of an excess quantity of fuel. The fuel injector comprises an actuator and a displacement amplifying chamber filled with fluid to which a large-diameter piston and a small-diameter piston working as the nozzle needle-actuating piston are exposed. The displacement amplifying chamber works to amplify and transmit displacement of the large-diameter piston by the actuator to the small-diameter piston. The fuel injector also includes a stopper which restricts movement of the small-diameter piston toward the displacement amplifying chamber to a given range, thereby suppressing the unwanted vibrations of the small-diameter piston.

Abstract: In a fuel infection valve, a valve chamber of a three ways valve is selectively communicated to drain and high pressure conduits and also communicated, via a main orifice, to a control chamber for controlling valve opening and closing operations of a nozzle needle. The control chamber may be communicated via the main orifice and the valve chamber to the drain conduit or the high pressure conduit, when a valve body is driven by a piezo actuator to open or close the drain conduit and close or open the high pressure conduit. The control chamber is always communicated via a sub orifice to the high pressure conduit without bypassing the three ways valve. Accordingly, hydraulic pressure in the control chamber is slowly decreased at a valve opening time and is rapidly increased at a valve closing time so that a lift characteristic of the nozzle needle is improved.

Abstract: A fuel injection valve having a valve member that is controlled by the pressure in a control pressure chamber and whose opening motion is influenced by way of a compensation pressure face of the valve member. This compensation pressure face adjoins a hydraulic chamber whose pressure is controlled with the aid of a piston which reduces the hydraulic initial stress of the hydraulic chamber, and keeps the fuel at an essentially constant value, and can compensate for volume changes of the hydraulic chamber by moving in opposition to a reference pressure.

Abstract: The invention relates to a switching valve (10) comprising a valve body (20) in which a flow passage (24) is formed which opens with its one end into a work space (42). A valve plate (44) is accommodated in the work space (42) and can be moved between a closure position and an opening position. A closure element (50) is arranged between the valve plate (44) and the opening (26) of the flow passage (24) and closes the latter when the valve plate (44) is located in its closure position.

Abstract: A pressure-controlled injector for injection systems for injecting fuel that is at high pressure into combustion chambers of internal combustion engines. A 3/2-way valve body is provided, which communicates with an inlet for fuel from a high-pressure collection chamber (common rail). The nozzle chamber of a nozzle needle can also be acted upon by fuel at high pressure. The stroke motion of the nozzle needle can be achieved via a hydraulic control chamber that can be pressure-relieved via a control line that has an externally actuatable control element.

Abstract: Disclosed in an injector for injecting fuel into the combustion chambers of an internal combustion engine, in which control part body is received movably in an injector housing and its opening and closing motion is effected via pressure relief of a control chamber. The pressure relief of the control chamber is controlled via an externally actuatable actuator. On the control part body, a sealing seat diameter that seals off the valve chamber is provided, which closes and opens the inlet from a common rail. An annular throttle element of variable cross section is located downstream of the sealing seat diameter of the control part body. An annular throttle element of variable cross section, or a throttle slide with a throttle, is located downstream of the sealing seat diameter of the control part body.

Abstract: The invention relates to an injector for injecting fuel that is at very high pressure, which is present at the injector in a common-rail inlet. The fuel acts on a control part, which is actuatable via a fuel volume contained in the control chamber. An inlet and an outlet of the control chamber are each provided with spring elements; the control chamber can be pressure-relieved via a valve element actuatable by means of an actuator. The control part in the injector housing is guided in two guide portions.

Abstract: A fuel injector including an injector housing, a nozzle, a needle valve, and a nozzle return chamber. The nozzle discharges a fuel from the fuel injector. The needle valve has a first end adjacent to the nozzle to control the discharge of the fuel through the nozzle. The nozzle return chamber is adjacent a second end of the needle valve and receives a working fluid to bias the needle valve into the closed position.

Abstract: A fuel injector includes a pressure intensifying chamber communicating with a fuel supply passage through a check valve, a plunger for pressure-intensifying fuel introduced into the pressure intensifying chamber, and a needle valve for injecting the fuel pressure-intensified in the pressure intensifying chamber through an injection port, wherein there is provided in the fuel supply passage a throttle passage normally communicating with a fuel drain passage, air being bled during startup while leaking fuel.

Abstract: A method of controlling the injection rate and injection pressure of an electromagnetic fuel injector assembly having a pressure balanced control valve including a solenoid and a valve member subject to the pressures developed by the injector and actuated by the solenoid to close the valve member against the biasing force of a spring. The control valve is supported in a valve bore in the injector body. The valve bore includes a relieved portion. The method includes the step of providing a first level of current to the solenoid for moving the valve member from an open to a closed position allowing the pressure in the injector to rise, providing a reduced level of current to the solenoid at preselected times during the injector event to unbalance the forces acting on the valve member thereby slightly unseating the valve member to regulate the injection pressure and injection rate of the fuel injector and ending current to the solenoid thereby moving the valve member to its open position.

Abstract: A fuel injector for an internal combustion engine is provided. The fuel injector has a simple structure that is easy to install and remove a piezoelectric valve actuator in and from the fuel injector and to adjust fuel injection characteristics finely and that allows an overall size of the fuel injector to be decreased. The fuel injector includes a housing to be installed in the engine and a structural element serving to install the piezoelectric valve actuator in the housing to be detachable easily. The piezoelectric valve actuator is retained in an actuator casing fitted in the housing so that it can expand or contract to move a needle valve. The actuator casing has an extensible portion in itself or is coupled to a bellows in alignment for enabling the piezoelectric valve actuator to expand, thereby allowing the size of the actuator casing to be minimized.

Abstract: A fuel injector comprising a valve needle slidable within a bore, a surface associated with the valve needle being exposed to the fuel pressure within a control chamber and an electromagnetically actuable control valve controlling communication between the control chamber and a low pressure chamber. The injector also comprises a damping arrangement arranged to damp pressure waves applied to the low pressure chamber.