INTERNAL COMBUSTION ENGINE

An internal combustion engine includes a pre-chamber. In another aspect, pressure within a pre-chamber is equal to or greater than pressure within a main combustion chamber at least prior to ignition in the main combustion chamber. A further aspect provides a supplemental piston creating pressure and supplying a fuel-air mixture into a pre-chamber, and a spark or glow plug has an end located within the pre-chamber for ignition of the mixture therein. In yet another aspect, internal combustion engine control software automatically controls pressure within a turbulent jet ignition pre-chamber, controls a valve-actuator to admit a fuel-air charge into the pre-chamber, and causes an ignitor to initiate combustion in the pressurized pre-chamber.

DETAILED DESCRIPTION

Referring toFIG. 1, an internal combustion engine11of an automotive vehicle includes an engine block13and a cylinder head15mounted thereto. A main driving piston17operably advances and retracts within a cylinder cavity19in order to drive a connecting rod21spanning between a pin23of piston17and a crank shaft25. Furthermore, cylinder head15includes an intake manifold31, an exhaust manifold33, a direct (not shown) or port fuel injector35and a turbulent jet ignition system41. A main combustion chamber43is located above main piston17partially within cylinder cavity19and cylinder head15, directly below turbulent jet ignition system41.

Referring now toFIGS. 2 and 3, turbulent jet ignition system41includes a cup-shaped housing51which internally defines the pre-chamber53therein. Housing51is secured to cylinder head15and a cap is in threaded engagement with an upper section of the housing. At least one and more preferably three to ten aperatures55are always open and connect pre-chamber53to main combustion chamber43. Each aperature is approximately1mm in diameter. Turbulent jet ignition system41further includes an ignitor61, such as a spark plug, glow plug or the like, which has an end63located within pre-chamber53for providing a spark or other heat ignition source for a fuel-rich, fuel-air mixture within pre-chamber53. As used herein, “rich” means the actual fuel to air ratio is greater than stoicheometric, and “lean” is less than the stoicheometric fuel to air ratio.

Additionally, turbulent jet ignition system41includes a supplemental piston65which moves within a piston housing67in response to hydraulic or pneumatic fluid flowing into an inlet port69and exiting an outlet port71. A biasing compression spring73is employed to retract piston65when the fluid actuating pressure is removed. Furthermore, a supply valve75is connected to a passageway77adjacent a bottom of piston housing67to operably allow the rich fuel-air mixture into a supplemental piston cavity for subsequent pushing of piston65outwardly through a conduit77. Conduit77connects a bottom of supplemental piston housing67to an intermediate portion of a poppet valve passageway79via a connecting conduit81in the cap. A poppet valve83retracts to a nominal position by way of a compression spring85and advances when an electro-magnetically operated solenoid87is energized. When energized, solenoid87causes poppet valve83to open which thereby allows the piston-pressurized and rich fuel-air charge to flow from supplemental piston housing67into pre-chamber53for ignition therein.

A first pressure transducer91is partially located within or is otherwise accessible to pre-chamber53for sensing internal pressure therein and a second pressure transducer93is partially located within or is otherwise accessible to main combustion chamber43for sensing an internal pressure therein. Transducers91and93are electrically connected to an electronic controller95, such as a programmable engine computer having a micro-processor, and non-transient computer ROM or RAM memory, capable of storing and running software including various programmed instructions.

Controller95has programmed instructions automatically controlling pressure within turbulent jet ignition pre-chamber53by causing movement of supplemental piston65and energization of solenoid87to open or close poppet valve83. Furthermore, controller has programmed instructions which cause ignitor61to create a spark for igniting the rich fuel-air charge in pressurized pre-chamber53. Moreover, controller95has programmed instructions receiving signals indicative of the sensed pressure in pre-chamber53via transducer91and main combustion chamber43via transducer93. The controller thereafter automatically adjusts the pressure in pre-chamber53, through piston65and valve83actuation, in a closed-loop manner for a subsequent cycle based at least on part on the sensed pressure signals. Moreover, the controller has additional programming instructions causing a fuel-air charge to be emitted into the pre-chamber at 0.9or richer, and the fuel-lean main fuel-air mixture to be injected into the main combustion chamber at a ratio of 1.8or leaner. The controller will automatically calculate and vary pre-chamber pressure, fuel quantity and ignition timing based on the sensed pressure signals, but also at least partly based on throttle positioning/signals, engine temperature, air temperature and the like.

The fuel-air mixture is mixed prior to entry into piston housing67which supplies pre-chamber53. It is noteworthy that piston65controls the fuel-air charge pressure in pre-chamber53so that the pre-chamber internal pressure matches that of the main combustion chamber to reduce if not eliminate gas flow or backfeeding between the two chambers during compression of driving piston17in order to maintain the desired fuel-air ratio in the pre-chamber prior to spark ignition therein. Piston65pressurizes pre-chamber53on a continuous basis during the driving piston stroke of the engine. It is preferred that the internal pre-chamber pressure be the same as or up to 5% greater than that of the main combustion chamber, at least prior to ignition in the main combustion chamber. This pre-chamber pressurization methodology prevents uneven burning in the pre-chamber due to the added piston-supplied air since supplemental piston65is supplying a mixed fuel-air charge and not simply only air or only fuel. The pre-chamber ionization signal, along with the pre-chamber pressure signal, during the pre-chamber combustion period, is used to achieve the desired intensity level of the turbulent jet ignition system41by adjusting the dwell current of spark plug ignitor61, and the pressure of the trapped fuel-air mixture in pre-chamber53. Accordingly, solenoid87actuates valve83to an open position for emitting the rich fuel-air charge into pre-chamber53timed between 50-110° before TDC, and in one configuration it is preferred that the timing be approximately 90° before TDC.

The air charge in the engine main chamber is regulated using the engine throttle and intake belt timing. The fuel is also injected into the main combustion chamber43either through port fuel injection or direct injection. No spark plug is required for main combustion chamber since the lean fuel-air mixture in main combustion chamber43is ignited by the previously ignited fuel-air charge pushed through aperatures55from the higher pressure pre-chamber53.

The present internal combustion engine and turbulent jet ignition system can use a variety of fuels such as gasoline, syngas, propane, natural gas and the like. The present turbulent jet ignition system has a reduced and slightly retarded ignition delay which advantageously reduces burn variability resulting from the pre-chamber ignition process and permits a wider range of operating conditions as the distributed ignition sites enable relatively small flame travel distances which promote higher burning rates. While the fuel-air mixture in the main combustion chamber can be stoichiometric, it is more advantageous to employ a leaner mixture up to 2or even 2.5(for propane and gasoline depending on the engine) thereby burning faster, improving flame propogation in lean mixtures, improving fuel efficiency, and reducing NOx emissions.FIG. 5illustrates the expected combustion propogation of spark ignition and jet ignition at different crank angles (“° CA”) and different fuel-air ratios, in an exemplary 1500 revolutions/minute and 3.3 bar IMEPn, operating condition. More complete lean fuel-air combustion is expected in the main combustion chamber using turbulent jet ignition of the present system.

While various features of the present invention have been disclosed, it should be appreciated that other variations may be employed. For example, supplemental piston65is illustrated above and aligned with driving piston17, however, alternate supplemental and driving piston configurations and positions can be employed, although various advantages of the present system may not be realized. Additionally, alternate fuel-air passageways, conduits, and ports may be provided, although some advantages may not be achieved. Additionally, it is envisioned that different types of valves, sensors and actuators may be used, but certain benefits may not be achieved. Alternately, variations in the fuel-air mixture can be used, but performance may suffer. Variations are not to be regarded as a departure from the present disclosure, and all such modifications are intended to be included within the scope and spirit of the present invention.