Abstract: A reagent dosing system for dosing a reagent into the exhaust gas stream of an internal combustion engine includes a reagent tank for storing a supply of reagent; an injector module including an atomizing dispenser and a positive-displacement metering pump which draws reagent from the reagent tank and delivers it to the dispenser; a supply line coupling the reagent tank to the injector module; a dosing control unit operable to control the injector module to inject reagent into the exhaust gas stream; and an additional priming pump arranged, in use, to urge reagent along the supply line toward the injector module under selected conditions.

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 pump assembly having improved cooling for use in a selective catalytic reduction system is disclosed. The pump assembly comprises a pump housing having a body portion and a nozzle portion extending from the body portion, a jacket including a cavity for receiving the pump housing, first and second ports for cooling fluid, and a flow guide disposed between the jacket and the pump housing. The cavity includes a first compartment for cooling fluid defined in part by the flow guide and in part by the pump housing and being in fluid communication with the first port; and a second compartment for cooling fluid defined in part by the flow guide and in part by the jacket. The first compartment is in fluid communication with the second port by way of the second compartment.

Abstract: A reagent dosing system for dosing a reagent into the exhaust gas stream of an internal combustion engine includes a reagent tank for storing a supply of reagent; an injector module including an atomising dispenser and a positive-displacement metering pump which draws reagent from the reagent tank and delivers it to the dispenser; a supply line coupling the reagent tank to the injector module; a dosing control unit operable to control the injector module to inject reagent into the exhaust gas stream; and an additional priming pump arranged, in use, to urge reagent along the supply line toward the injector module under selected conditions.

Abstract: A reagent dosing system for dosing a reagent into the exhaust gas stream of an internal combustion engine includes a reagent tank for storing a supply of reagent; an injector module including an atomizing dispenser and a positive-displacement metering pump which draws reagent from the reagent tank and delivers it to the dispenser; a supply line coupling the reagent tank to the injector module; a dosing control unit operable to control the injector module to inject reagent into the exhaust gas stream; and an additional priming pump arranged, in use, to urge reagent along the supply line toward the injector module under selected conditions.

Abstract: A mounting arrangement for attaching a pump arrangement to an exhaust pipe at a boss includes a delivery nozzle section and a remaining section including a pump body. The mounting arrangement includes a packing for supporting the pump body at the remaining section of the pump arrangement.

Abstract: A method of dosing a reagent into an exhaust gas stream of an internal combustion engine having an SCR catalyst, the method comprising injecting reagent from a reagent tank into the exhaust gas stream at a position upstream of the SCR catalyst using a reagent injector in accordance with a first dosing schedule in order to remediate a predetermined proportion of NOx in the exhaust gas stream, the first dosing schedule being associated with a first range of engine operating conditions; and injecting reagent from the reagent tank into the exhaust gas stream at a position upstream of the SCR catalyst using a reagent injector in accordance with a second dosing schedule in order to enable heat transfer between the reagent injector and said injected reagent, the second dosing schedule being associated with a second range of engine operating conditions.

Abstract: A pump assembly having improved cooling for use in a selective catalytic reduction system is disclosed. The pump assembly comprises a pump housing having a body portion and a nozzle portion extending from the body portion, a jacket including a cavity for receiving the pump housing, first and second ports for cooling fluid, and a flow guide disposed between the jacket and the pump housing. The cavity includes a first compartment for cooling fluid defined in part by the flow guide and in part by the pump housing and being in fluid communication with the first port; and a second compartment for cooling fluid defined in part by the flow guide and in part by the jacket. The first compartment is in fluid communication with the second port by way of the second compartment.

Abstract: A mounting arrangement for attaching a pump arrangement to an exhaust pipe at a boss includes a delivery nozzle section and a remaining section including a pump body. The mounting arrangement includes a packing for supporting the pump body at the remaining section of the pump arrangement.

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 piezoelectric actuator comprises a stack of piezoelectric elements formed from piezoelectric material, a plurality of positive internal electrodes interdigitated with a plurality of negative internal electrodes to define active regions of the piezoelectric material which are responsive to a voltage being applied across the internal electrodes, in use. The active regions are responsive to voltage applied across the internal electrodes, in use. The piezoelectric actuator also comprises an external positive electrode for connection to the positive internal electrodes and an external negative electrode for connection to the negative internal electrodes.

Abstract: A piezoelectric actuator for use in a fuel injection system of an internal combustion engine, the actuator comprising a stack of ferroelectric layers; an encapsulation for protecting the stack from the ingress of liquid; and oxygenation means for providing oxygen to the ferroelectric layers, the means positioned between the encapsulation and stack. The oxygenation means is preferably impregnated in a fabric which forms a layer between the encapsulation and the stack.

Abstract: A piezoelectric actuator for use in a fuel injection system of an internal combustion engine, the actuator comprising a stack of ferroelectric layers; an encapsulation for protecting the stack from the ingress of liquid; and oxygenation means for providing oxygen to the ferroelectric layers, the means positioned between the encapsulation and stack. The oxygenation means is preferably impregnated in a fabric which forms a layer between the encapsulation and the stack.

Abstract: A method of assembling a piezoelectric actuator arrangement comprises providing a piezoelectric element having first and second ends and arranging the piezoelectric element within a sleeve member such that the inner surface of the sleeve member defines, together with the outer surface of the piezoelectric element, a chamber for receiving a first filler material. The first filler material is injected into the chamber and a heating effect is applied to the sleeve member such that the sleeve member deforms to seal against the first filler material.

Abstract: A method of assembling a piezoelectric actuator arrangement (10) comprises the steps of providing a piezoelectric element (12) having first and second ends and arranging the piezoelectric element (12) within a sleeve member (20) such that the inner surface of the sleeve member (20) defines, together with the outer surface of the piezoelectric element (12), a chamber (24) for receiving a first filler material (30). The first filler material (30) is injected into the chamber (24) and a heating effect is applied to the sleeve member (20) such that the sleeve member (20) deforms to seal against the first filler material (30).

Abstract: An actuator arrangement comprising a piezoelectric element formed from a piezoelectric material, a first end of the piezoelectric element cooperating with an input piston member slidable within a bore. A surface associated with the input piston member defines, in part, a control chamber for fluid, fluid pressure within the control chamber acting on a surface associated with an output piston member. The fluid within the control chamber is substantially incompressible such that, in use, movement of the input piston member is transmitted to the output piston member, the piezoelectric element being arranged within a second chamber for fluid such that fluid pressure within the second chamber exerts a force on at least a part of the surface of the piezoelectric element which serves to oppose the load exerted on the piezoelectric element due to fluid pressure within the control chamber, thereby suppressing distortions in the piezoelectric material.

Abstract: A fuel injector comprising a valve needle which is slidable within a bore and engageable with a seating to control fuel delivery through first and second outlet openings. The valve needle is moveable between a closed position and first and second fuel injecting positions. The fuel injector further comprises a fuel supply passage for supplying fuel under pressure to the bore and a control chamber which is arranged to receive fuel from the fuel passage, in use. The valve needle is acted upon in use by a force due to fuel pressure within the control chamber. An actuator arrangement controls fuel pressure within the control chamber, and a damping means are provided for damping movement of the valve needle away from the seating into the first or second fuel injecting position. The supply passage for fuel may be provided with a restricted flow passage which serves to limit the amplitude of pressure waves within the supply passage.

Abstract: A method is provided for detecting injection events in a piezoelectric actuated fuel injector. The method comprises the steps of: (a) providing a piezoelectric element for actuating the injector valve; (b) applying a voltage to the piezoelectric element, thereby actuating the injector valve; and (c) monitoring at least one of the voltage or current associated with the piezoelectric element, wherein changes in voltage or current are indicative of injection events in the fuel injector.

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: A fuel injector comprises a valve needle biased by a spring towards a seating. The spring engages a spring abutment member which is moveable with a piston member. The spring abutment member defines, with a member carried by the needle, a damping chamber which communicates through a restricted passage with a low pressure drain to damp movement of the needle relative to the piston member.