Engine operating strategy using pulsed injection of gaseous hydrogen fuel
Operating an engine includes energizing an electrical actuator for a valve in a fuel injector according to a waveform alternating a plurality of on-times with a plurality of dwell times, and outputting a pulsed injection of a gaseous hydrogen fuel from the fuel injector entraining air between pulses of the gaseous hydrogen fuel. Entrainment breaks are produced between the plurality of pulses in a spray cone of the pulsed injection. The gaseous hydrogen fuel and air experience enhanced in-cylinder mixing based upon the air entrainment. Related apparatus is also disclosed.
1 . A method of operating an engine comprising:
moving a piston between a bottom-dead-center position and a top-dead-center position in a cylinder in an engine having an engine housing;
energizing an electrical actuator for a valve in a fuel injector according to a waveform alternating a plurality of on-times with a plurality of dwell times;
outputting a pulsed injection of a gaseous hydrogen fuel from the fuel injector and, inside the engine housing, entraining air into the pulsed injection between a plurality of pulses of the gaseous hydrogen fuel, based on the energizing the electrical actuator; and
combusting the gaseous hydrogen fuel and air in the cylinder.
2 . The method of claim 1 wherein the waveform includes a square waveform and the plurality of on-times are longer in duration than the plurality of dwell times.
3 . The method of claim 2 wherein the plurality of pulses of the pulsed injection includes a number of pulses greater than two.
4 . The method of claim 3 wherein the number of pulses is from 3 to 8.
5 . The method of claim 1 wherein the outputting a pulsed injection includes outputting the pulsed injection into a feed of pressurized intake air conveyed into the cylinder.
6 . The method of claim 1 wherein the outputting a pulsed injection includes outputting the pulsed injection directly into the cylinder.
7 . The method of claim 6 wherein the outputting a pulsed injection includes outputting the pulsed injection prior to a crank angle timing corresponding to the top-dead-center position of the piston.
8 . The method of claim 7 wherein the crank angle timing is from 40° prior to an intake valve closing timing to 40° after an intake valve closing timing.
9 . The method of claim 8 wherein the pulsed injection is split around the intake valve closing timing.
10 . The method of claim 1 wherein the gaseous hydrogen fuel includes gaseous molecular hydrogen, and further comprising feeding the gaseous hydrogen fuel to the fuel injector at an injection pressure.
11 . A gaseous fuel engine system comprising:
an internal combustion engine having a cylinder formed therein, and a piston movable in the cylinder between a bottom-dead-center position and a top-dead-center position and including a center cone;
a fuel system including a gaseous hydrogen fuel supply, a fuel injector fluid connected to the gaseous hydrogen fuel supply and having a valve electrical actuator, and the fuel injector extending into the cylinder and including a fuel outlet arranged to produce a spray cone of injected gaseous hydrogen fuel advanced from the fuel outlet and targeting the center cone for impingement;
the fuel system further including a fueling control unit structured to:
output electrical control commands to the valve electrical actuator;
energize the valve electrical actuator based on the electrical control commands according to a pulsed waveform; and
cause the fuel injector to output a pulsed injection of the gaseous hydrogen fuel forming the spray cone for combustion in the cylinder based on the energizing of the valve electrical actuator.
12 . The engine system of claim 11 wherein the pulsed waveform includes a square waveform alternating a plurality of on-times with a plurality of dwell times.
13 . The engine system of claim 12 wherein the plurality of on-times are longer in duration than the plurality of dwell times.
14 . The engine system of claim 13 wherein the pulsed injection includes a plurality of pulses corresponding in number to the plurality of on-times, and the number is from 3 to 8.
15 . The engine system of claim 12 wherein the fuel injector includes a total number of fuel outlet holes of 3 or less.
16 . The engine system of claim 14 wherein the internal combustion engine further includes an intake port extending to the cylinder, an intake runner extending to the intake port, and a fuel injector fluid connected to the gaseous hydrogen fuel supply and extending into one of the intake port or the intake runner.
17 . The engine system of claim 14 wherein the fuel injector extends into the cylinder.
18 . A method of operating an engine comprising:
feeding a gaseous hydrogen fuel to a fuel injector coupled to an engine;
actuating the fuel injector to output a pulsed injection of the gaseous hydrogen fuel into intake air in the engine;
producing a plurality of entrainment breaks between a plurality of pulses of the gaseous hydrogen fuel in a spray cone of the pulsed injection;
entraining air into the spray cone in the plurality of entrainment breaks; and
combusting the gaseous hydrogen fuel and air in a cylinder in the engine.
19 . The method of claim 18 wherein the feeding the gaseous hydrogen fuel to the fuel injector includes feeding the gaseous hydrogen fuel at an injection pressure.
20 . The method of claim 19 wherein the plurality of pulses includes from 3 to 8 pulses split around an intake valve closing timing.