摘要:
A fuel injector for a machine is disclosed. The fuel injector has a nozzle member with a first end and a second end. The first end of the fuel injector has at least one orifice. The fuel injector also has a control chamber located at the second end of the nozzle member with an end wall portion approximately orthogonal to an axial direction of the nozzle member. The fuel injector further has a port disposed in the end wall portion of the control chamber and at least one passageway in fluid communication with the control chamber via the port. The fuel injector additionally has a needle valve element with a tip end and a base end. The tip end is configured to selectively block fuel flow through the at least one orifice. The base end has a recess configured to cap off the port.
摘要:
In one class of fuel injection systems, the individual fuel injectors cycle between high and low pressure during and between injection sequences in a given engine cycle. The fuel injectors may be hydraulically actuated, mechanically actuated, and possibly include common rail injectors equipped with an admission valve that enable the fuel injectors to cycle between high and low pressures. Many of these fuel injection systems also include a directly controlled nozzle valve that can apply or relieve pressure on a closing hydraulic surface associated with the nozzle valve. The nozzle valve is typically spring-biased and therefore has a pre-defined valve opening pressure that defines at what fuel pressure the nozzle valve will open when pressure is relieved on its closing hydraulic surface. While these fuel injection systems can produce a wide variety of rate shapes and injection sequences, generally, an injection sequence of particular interest is one that includes a relatively small volume pilot injection followed quickly in time by a relatively large volume main injection. In order to make the accuracy of the pilot injection more consistent, the nozzle valve is held closed while fuel pressure in the fuel injector builds and surpasses the valve opening pressure of the nozzle valve. This strategy helps to alleviate sensitivity of the pilot injection volume to inherent variability factors, such as geometrical tolerances, within and between fuel injectors.
摘要:
An internal combustion engine (10) has an intake system (12) that includes a turbocharger (32). An engine control (30) processes data for controlling the opening of the exhaust valves (24) and for controlling fueling of the engine in relation to the engine operating cycle. In response to initiation of engine acceleration, the control increasingly retards exhaust valve opening in relation to the engine operating cycle to cause the turbocharger to increase pressure in the intake manifold (14) and increases engine fueling in relation to the increased pressure in the intake manifold.
摘要:
A turbocharger (32) creates intake manifold boost for a diesel engine (10) that has a variable valve actuation mechanism. At times, exhaust valve opening (EVO) is increasingly retarded in relation to the engine operating cycle (56) to cause the turbocharger to increase boost, engine fueling is also increased in relation to the increased boost (58), and in response to any incipient surging of the compressor resulting from such increasingly retarded exhaust valve opening and such increased engine fueling, compressed charge air is bled from the intake manifold through the combustion chambers to the exhaust system (62) to counter the incipient surging and thereby avoid any significant turbocharger surge. The bleeding is accomplished by keeping the exhaust valves (24) slightly open beyond the time that they would otherwise close.
摘要:
An exhaust aftertreatment system including an exhaust flow area, a first bank of one or more exhaust treatment devices in fluid communication with the exhaust flow area and a second bank of one or more exhaust treatment devices in fluid communication with the exhaust flow area. The first bank may be arranged in parallel with the second bank and inlet of the first bank is configured to provide greater flow resistance to the exhaust than the inlet of the second bank.
摘要:
An engine exhaust aftertreatment system including a mixer disposed in the exhaust stream. The mixer includes a mesh section having a mesh of wires and may include a baffle section having a deflector that redirects a direction of flow of the exhaust stream. The mesh section may not extend across an entire width of an exhaust conduit containing the exhaust stream. The mesh section may also be sized and located to intersect the reductant introduced by the injector.
摘要:
An exhaust aftertreatment system including an exhaust flow area, a first bank of one or more exhaust treatment devices in fluid communication with the exhaust flow area and a second bank of one or more exhaust treatment devices in fluid communication with the exhaust flow area. The first bank may be arranged in parallel with the second bank and inlet of the first bank is configured to provide greater flow resistance to the exhaust than the inlet of the second bank
摘要:
An engine exhaust aftertreatment system including a selective catalytic reduction (SCR) system. The SCR system includes a reductant injection system configured to introduce a reductant into a exhaust stream of a engine, a SCR catalysts configured to reduce NOx in the presence of a reductant, and a SCR monitoring system configured to determine temperatures associated with the SCR system. The SCR system also includes a heat source configured to raise the temperature of the exhaust stream and a controller configured to operate the heat source to reach exhaust stream temperatures in the SCR system of at least about 400 degrees Celsius based on the temperature associated with the SCR system.
摘要:
An emissions control system is disclosed. The emissions control system may have a first exhaust treatment device. The emissions control system may also have an end cap defining a mixing chamber connected to an end of the first exhaust treatment device. The mixing chamber may be configured to promote mixing between a flow of exhaust received from the first exhaust treatment device and a reductant. The emissions control system may further have a second exhaust treatment device configured to receive the flow of exhaust and reductant after it passes through the mixing chamber.
摘要:
A fuel injector for a work machine is disclosed. The fuel injector has nozzle member having at least one orifice and a needle valve element having a tip end. The needle valve element is axially movable to selectively allow and block fuel flow through the at least one orifice with the tip end. The fuel injector also has at least one supply passageway in communication with the tip end of the needle valve and a variable restrictive device disposed within the at least one supply passageway.