Abstract: The present invention relates to an actuator arrangement for use in a fuel injector, comprising: a piezoelectric actuator having a body section, said body section having a first end piece and a second end piece; a rigid encapsulation member which encloses the body section and the end pieces, wherein potting material is fitted between the rigid encapsulation member and the body section, wherein the first end piece is slideably fitted into the rigid encapsulation and the second end piece is fixed to or integrated into the encapsulation member.

Abstract: A piezoelectric actuator comprises a co-fired stack of piezoelectric elements formed from a piezoelectric material and a plurality of positive internal electrodes interdigitated with a plurality of negative internal electrodes throughout the stack to define active regions of the piezoelectric material which are responsive to a voltage applied across the internal electrodes, in use. An external positive electrode connects with the positive internal electrodes and an external negative electrode connects with the negative internal electrodes. The actuator is characterized in that the stack further comprises means for deliberately creating artificial cracks within the stack at a location at which the artificial cracks do not give rise to a short circuit between the internal electrodes but serve to relieve stresses within the piezoelectric material.

Abstract: A fuel injection apparatus for an internal combustion engine includes a fuel supply passage and a valve arrangement for controlling fuel pressure within the fuel supply passage. The valve arrangement includes a valve member movable between an open position in which the fuel supply passage communicates with a low pressure fuel drain and a closed position in which communication between the fuel supply passage and the low pressure fuel drain is prevented. The valve arrangement comprises damping means for controlling and/or damping movement of the valve member between the closed and open positions.

Abstract: A control valve, for use in controlling fuel pressure within a control chamber, comprises a control valve member, first flow restriction and second flow restriction. The control valve member is movable between a first position, and a second position. The first flow restriction is arranged to maintain a first pressure upstream of the first flow restriction when the control valve member is in transition between the first position and the second position. The second flow restriction is positioned downstream of the first flow restriction and is arranged to maintain a second pressure upstream of the second flow restriction. The second flow restriction is dimensioned and located relative to the first flow restriction such that in transition between the first and second positions the net force exerted on the control valve member by the first pressure balances the net force exerted on the control valve member by the second pressure.

Abstract: A method of manufacturing a metal housing (14) includes providing a first passage (10) through the metal housing (14) and providing a second passage (12) through the metal housing (14), wherein the second passage (12) includes a region of intersection (20) which intersects the first passage (10) to define an opening (22, 122, 222) into the first passage (10). The method further includes subjecting the metal housing (14) to a heat treatment process to carburise an internal surface of the first and/or second passage (10, 12) and, subsequent to the carburization process, applying a hard stage electrochemical machining process to the carburised internal surface of the first and/or second passage (10, 12) to improve surface finish. Another aspect of the invention includes providing a second passage (12) through the metal housing (14) by means of a tool (46), such as an electrochemical machining electrode, having an active region without rotational symmetry about its axis (Y-Y).

Abstract: A fault detection method is provided for detecting faults in an injector arrangement. The injector arrangement includes one or more piezoelectric fuel injectors connected in an injector drive circuit, and the injector drive circuit is arranged to control operation of the one or more piezoelectric fuel injectors. The fault detection method includes determining a sample voltage at a sample point in the injector drive circuit at a first sample time. The sample voltage is the voltage on an injector or is related to the voltage on an injector. The method further includes calculating a range of predicted voltages expected at the sample point at a second sample time following the first sample time, and determining the sample voltage at the sample point at the second sample time. The presence of a fault is detected if the sample voltage determined at the sample point at the second sample time is not within the range of predicted voltages.

Abstract: A method for enshrouding an actuator for use in a fuel injector, comprising the steps of providing an actuator having a body section, a first end piece and a second end piece; providing a shroud having first and second ends; applying a sealant material to at least one portion of an exterior surface of the end pieces, and/or to at least one part of the shroud; and enshrouding the actuator with the shroud, such that the sealant material provides an intermediate layer between the end pieces and the shroud and forms a fluid-tight seal between them.

Abstract: A fuel injector assembly comprising an injector body having a leading end, a fuel inlet passage, a backleak passage and a trailing end that terminates in an end surface; a cap that fits over the trailing end of the injector body to define therebetween a chamber for receiving fuel from said backleak passage; and a seal for sealing said chamber to prevent the flow of fuel therefrom, wherein said seal is disposed between said end surface of the trailing end and an inlet end of said fuel inlet passage.

Abstract: A tappet suitable for use with a fluid pump includes a side wall portion and an end face which define an internal chamber of the tappet, the end face having a drive surface for co-operating with a drive arrangement, in use, and a plurality of vents through the end face for allowing fluid flow between the internal chamber and an area outside the tappet. A plurality of longitudinal grooves are formed in an internal surface of the side wall portion, the grooves communicating with respective the vents to form a flow path for fluid into the internal chamber.

Abstract: An injection device for administering a reagent into an exhaust chamber of an internal combustion engine, comprising a device inlet and a device outlet and a sub-assembly held securely within a device housing. The sub-assembly comprises (i) valve housing defining a valve seat, (ii) valve means movable outwardly from the valve housing, away from the valve seat, to permit the reagent to be delivered into the exhaust chamber through the device outlet, whereby a force is applied to the valve means due to reagent delivered to the device inlet which serves to urge the valve means away from the valve seat, and (iii) bias means for applying a biasing force to the valve means which serves to urge the valve means against the valve seat so as to prevent delivery of the reagent through the device outlet into the exhaust chamber.

Abstract: A piezoelectric actuator for use in a diesel engine. The actuator comprises a piezoelectric element which is encapsulated such that a layer of gas at a pressure above atmospheric pressure surrounds the piezoelectric element. The presence of the gas within the encapsulation around the element avoids the need to passivate electrodes exposed on the surface of the element.

Abstract: A method and apparatus for detecting faults in an injector arrangement is described. The injector arrangement comprises a plurality of piezoelectric injectors that are located in parallel branches of an injector bank circuit of an injector drive circuit. Each branch of the injector bank circuit comprises a high side isolation switch. The high side isolation switches are each operable to enable an associated piezoelectric injector in the injector bank circuit when closed, and disable the associated piezoelectric injector in the injector bank circuit when open. The fault detection method comprises the steps of operating the high side isolation switches so as to enable one of the piezoelectric injectors and disable the other piezoelectric injector(s), and performing diagnostics to detect the presence or absence of faults on the enabled piezoelectric injector.

Abstract: A fuel pump for use in an internal combustion engine, the fuel pump comprising a pumping plunger for pressurising fuel within a pump chamber during a plunger pumping stroke, a rider member co-operable with a drive, and an interface member, for example a foot of the plunger or an intermediate tappet, for imparting drive from the rider member to the pumping plunger to perform the plunger pumping stroke. The interface member comprises an arcuate contact surface co-operable with the rider member. The inventive concept also extends to a pumping plunger for pressurising fuel within a pump chamber of a fuel pump, the pumping plunger comprising a foot having an arcuate contact surface for engaging a rider member of a fuel pump in use.

Abstract: An apparatus and method is described for testing a multi-hole fuel injector nozzle. The apparatus comprises mounting means for the multi-hole nozzle and fuel supply means for supplying fuel to the multi-hole nozzle. The multi-hole nozzle is mounted outside a measurement chamber for capturing the fuel spray from an individual spray hole outlet of the multi-hole nozzle. In one embodiment, the apparatus includes a spray target plate, located within the measurement chamber, at which the fuel spray is directed. The spray target plate (28) is connected to a remote pressure sensor, which is used to determine the spray force of the fuel spray acting on the spray target plate. The apparatus is further arranged to determine the mass flow rate of the fuel spray. A new parameter, referred to as ‘momentum efficiency’ is defined, and calculated using the determined values of spray force and mass flow rate.

Abstract: A method for controlling the displacement of a stack of a piezoelectric actuator adapted for use in a fuel injector in order to control the fuel injection rate and volume. The method comprises driving a varying current through the stack during an opening phase including a first opening stage and a second opening stage; driving the stack during the first opening stage with a first opening current level for a first opening time period and driving the stack during the second opening stage with a second opening current level for a second opening time period. The second opening current level is less than the first opening current level and the current levels are selected so that the fuel injection rate in the opening phase includes a first portion corresponding to the first opening stage having a gradient that is steeper than a second portion corresponding to the second opening stage.

Abstract: A fuel injection system for an internal combustion engine comprises: a first fuel injector which is arranged within a housing unit; an accumulator volume for supplying fuel to the first fuel injector; a first fuel pump arrangement comprising a pumping plunger which is driven, in use, to cause pressurisation of fuel within a first pump chamber; a first metering valve which is operable to control fuel flow into the first pump chamber; a first fuel passage providing communication between the first pump chamber and the accumulator volume; and a first non-return valve located in the first fuel passage between the first pump chamber and the accumulator volume; wherein the first fuel injector communicates with the first fuel passage at a position between the first non-return valve and the accumulator volume; and wherein communication between the first fuel injector and the accumulator volume is uninterrupted.

Abstract: A method and apparatus for controlling fuel injection in an engine is described. The apparatus comprises at least one fuel injector which is connected in an injector drive circuit powered by a power source. The method comprises determining an injection event sequence of the at least one fuel injector based on at least one engine operating parameter, determining a magnitude of a load parameter of the power source, comparing the magnitude to a predetermined threshold level for the load parameter, and determining a modified injection event sequence in the event that the magnitude is substantially equal to or greater than the predetermined threshold level.

Abstract: A method of providing electronic trim data for a fuel injection device to an engine system, the method comprising: reading an identifier associated with the fuel injection device; accessing a database containing trim data associated with the identifier; downloading the trim data for the fuel injection device; uploading the downloaded trim data to the engine system for use in controlling fuel injection device operation.

Abstract: A pumping assembly is provided which is suitable for use in a variety of dosing pumps. The pumping assembly comprises a pump body with a pump bore, and a sleeve fixed within the pump bore. The sleeve has a first end, a second end and a sleeve bore. A plunger is adapted to enter the first end of the sleeve and to reciprocate within the sleeve bore. The sleeve has at least one port to allow fluid flow through a wall of the sleeve. The, or each, port is elongated in a direction substantially orthogonal to a direction of reciprocation.

Abstract: A method of reducing tensile stress within a drilled element 100 at an intersection 130 between a primary bore 110 and a secondary bore 120 comprises the following steps. A first face of the drilled element 100 is loaded with a first loading element. A compressive hoop stress is generated where the first face of the drilled element 100 is loaded by the first loading element, and the intersection 130 is sufficiently close to the first face of the drilled element 100 such that the compressive hoop stress counteracts tensile stress in the drilled element 100 at the intersection 130. A suitable drilled element 100 and fluid flow systems, such as a fuel injector, including such a drilled element 100 are also described.