Abstract:
A compression-ignition engine (10) comprises an exhaust system (16) with an exhaust gas after-treatment assembly, the after-treatment assembly comprising a three-way catalyst device (30) and an SCR device (34), the three-way catalyst device being arranged upstream the SCR device in close-coupled position with respect to the engine. An engine control unit (47) is provided for controlling operation of the engine. The engine control unit is configured to monitor the temperature of the SCR device and to control the engine to change over from an operation with a lean air/fuel mixture to an operation with a stoichiometric or a rich air/fuel mixture in response to the temperature of the SCR device dropping below a temperature threshold.
Abstract:
An injector (50) for a fuel injection system comprising: input means (51a, 51b) for receiving drive signals from an injector drive circuit (76) for controlling operation of the injector, and; an ID chip (62) wherein the injector further comprises an electronic latch means (68) arranged to move between a first state in which the electronic latch means is arranged to be enabled such that the ID chip is in communication with the injector drive circuit via the input means, and a second state in which the electronic latch means is arranged to be disabled such that the ID chip is not in communication with the injector drive circuit via the input means wherein the electronic latch means is arranged to move from the first state to the second state upon receipt at the injector of a drive pulse signal from the injector drive circuit.
Abstract:
A fuel injector (100; 200; 300) for an internal combustion engine is disclosed. The injector includes a slave piston (130; 230; 330) provided with a control bore (144; 244; 344) and associated with a valve needle (110; 210; 310), such that movement of the slave piston causes movement of the valve needle. An end of the slave piston remote from the valve needle is exposed to fuel pressure in a control chamber (152; 252; 352) of the injector, in use. A control piston (148; 348) is operable to move relative to the slave piston so as to control fuel flow through first and second control ports that connect the control bore to a high-pressure fuel supply and a low-pressure drain respectively. By suitable positioning of the control piston, the valve needle can be biased in an opening direction and in a closing direction and, optionally, the valve needle can be held in one or more intermediate positions between its fully-lifted and fully-seated positions. Proportional control of the position and velocity of the valve needle is possible, and a low-force actuator can be used to control the valve needle.
Abstract:
An inlet valve assembly (14) for a high-pressure fuel pump is disclosed. The inlet valve assembly comprises an inlet valve member (28) moveable between open and closed positions to control the fuel flow from a source (24) of low-pressure fuel to a pumping chamber (16) of the fuel pump, a first biasing spring (70) arranged to apply a first force to the valve member (28) in an opening direction, a second biasing spring (74) arranged to apply a second force to the valve member (28) in a closing direction, and an actuator arrangement (50) operable to remove the first force from the valve member (28), thereby to allow the valve member (28) to move into its closed position.
Abstract:
An overhead-camshaft internal combustion engine is disclosed, in which the fuel pumps are arranged to use efficiently the space within a cylinder head assembly (100) of the engine. The cylinder head assembly (100) includes a cylinder head block (102), and the engine comprises a camshaft (106) mounted longitudinally with respect to the cylinder head assembly (100), the camshaft (106) being rotatable about a camshaft axis (A) and having a plurality of inlet and exhaust cams for actuating associated inlet and exhaust valves (116a; 116b) of the engine, and at least one fuel pump comprising a unit pump assembly (110) driven directly by a respective pump cam (130) provided on the camshaft (106), the unit pump assembly (110) being elongate to define a pump axis (P). The engine further comprises a plurality of rocker arms (118) driven by the inlet and exhaust cams and arranged to actuate the inlet and exhaust valves (116a, 116b). Each rocker arm (118) is pivotable about a rocker arm axis (R) which is substantially parallel to the camshaft axis (A). The or each pump assembly (110) is mounted between the rocker arm axis (A) and the cylinder head block (102).
Abstract:
A non-return valve assembly (100) for a high-pressure fuel injection system is disclosed. The valve (100) comprises a valve chamber (102) defined in part by a first body (106) and in part by a second body (108) and defining a valve chamber wall (118), an inlet passage (110) formed in the first body (106) and opening into the valve chamber (102) at a valve seat (116) defined by the first body (106), an outlet passage (112), and a valve ball (114) received within the valve chamber (102) and engageable with the valve seat (116) so as to interrupt fluid flow from the outlet passage (112) to the inlet passage (110) through the valve chamber (102). The valve chamber wall (118) comprises a plurality of guide portions (122a) to guide the valve ball (114) in substantially linear movement within the valve chamber (102).
Abstract:
A fuel injector for use in a fuel system for an internal combustion engine is disclosed. The fuel injector comprises a supply means (24, 24a) for high pressure fuel, an injection nozzle (25) including a valve needle (26) which is engageable with a valve needle seating (28) to control fuel delivery from the injector, a surface associated with the valve needle (26) being exposed to fuel pressure within a control chamber (42), a first filling flow path (44) providing flow from the supply means (24) into the control chamber (42), and a control valve (48) for controlling fuel pressure within the control chamber (42). The control valve (48) comprises a valve housing (80) that defines, in part, a first valve chamber (104) and a second valve chamber (106), and a control valve member (60) slidable within a guide bore (86) of the valve housing (80). The injector further comprises a drain flow path (50) including a drain restriction (50a) and permitting flow from the control chamber (42) to the second valve chamber (106) when the control valve member (60) is in the second state, and a second filling flow path (47) permitting flow from the first valve chamber (104) into the control chamber (42) when the control valve member (60) is in the first state, wherein the second filling flow path (47) bypasses the drain restriction (50a). The drain flow path (50) and the second filling flow path (47) are formed within the valve housing (80).
Abstract:
A valve assembly for controlling the rate of flow of fluid between a valve inlet (18) and a valve outlet (22) comprises a valve housing (10), and a spool valve member (14) that is movable axially within a valve bore (12) provided in the valve housing (10) in an opening direction and a closing direction. The spool valve member (14) is provided with a blind bore (28), the open end of which communicates with the valve outlet, and at least one opening (32, 34; 40; 50, 52, 54, 56) into the blind bore, the at least one opening communicating, to a variable degree dependent on the axial position of the spool valve member (14) within the valve bore (12), with the valve inlet (18). The valve inlet (18) comprises a first boundary (24) and a second boundary (26), wherein the first boundary (24) acts as a control edge so that for axial positions of the spool valve member (14) in which the opening (30, 32; 40; 50, 52, 54, 56) does not overlap the control edge there is no flow into the outlet (22).A blind end (30) of the blind bore (28) is positioned, for all positions of the spool valve member (14) within the valve bore (12), beyond the second boundary (26) in the opening direction of the spool valve member (14).
Abstract:
A method of operating an internal combustion engine is proposed, the engine comprising an exhaust system with a DOC and a DPF and, downstream thereof a SCR catalyst. The ECU is configured to allow operation in at least one of a normal mode and a heat-up mode. A predicted temperature evolution of said second exhaust after treatment means is regularly determined based on a thermal model taking into account the thermal inertia of the exhaust system and having as input the current temperatures of the DOC/DPF and SCR. The predicted temperature evolution of SCR is indicative of the temperature that the SCR may reach during a simulated time period in case the operating mode. The engine operating mode is changed depending on the predicted temperature evolution.
Abstract:
A method of determining a minimum drive pulse (MDP) for an injector (7) in a fuel system (1) within an engine, the injector being associated with a fuel source (4), the method comprising: (a) measuring a first pressure in the fuel system; (b) sending (90) a drive pulse of a first length to the injector; (c) measuring a second pressure in the fuel system; (d) determining if an injection event has occurred by calculating the pressure difference between the first and second pressures and comparing to a threshold pressure difference; (e) repeating (a) to (d) with drive pulses of progressively increasing lengths until an injection event has occurred and setting the drive pulse length associated with the injection event as the MDP of the injector, wherein the fuel source is periodically pressurised.