Internal-combustion engines – Combustion chamber – Having squish area
Reexamination Certificate
2000-02-01
2001-07-31
Solis, Erick (Department: 3747)
Internal-combustion engines
Combustion chamber
Having squish area
C123S305000, C123S636000, C123S162000
Reexamination Certificate
active
06267107
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to spark ignition internal combustion (IC) engines and to the improved ignition and combustion of air-fuel mixtures in IC engines through the faster and more vigorous combustion of the air-fuel mixture brought about by high air-flows of both the directed bulk flow type and of the more random turbulent flow type produced in a highly compact combustion zone of the combustion chamber. In particular, the invention relates to combustion systems which can simultaneously produce high directed bulk flow at the spark plug site at the time of ignition and more random and intense turbulent flow inside a compact combustion chamber during the time of ignition and combustion to speed-up the bum. In particularly, the invention relates to a system which involves the design and control of high flows, high energy ignition spark discharges, and resulting intense flame kernels, all three of which interact among themselves in ways that produce a very rapid and controlled burn in a compact combustion zone for low NOx emissions and high engine efficiency through lean and high EGR (exhaust gas recirculation) combustion at a high engine expansion ratio.
BACKGROUND OF THE INVENTION AND PRIOR ART
High flows are used in IC engines to improve engine efficiency and emissions through rapid combustion of lean and high EGR air-fuel mixtures. These flows are either swirl, tumble (vertical vortex), or squish. The predominant type of flow used is swirl, especially for the purpose of generating mixture stratification at the spark plug site to allow for ignition of lean mixtures. Numerous examples of these exist, especially with Japanese manufacturers such as Toyota, Mazda, and others. To a lesser extent tumble flow is used, as in the Mitsubishi Vertical Vortex (MVV) engine now in production. Squish is rarely used for efficiency and emissions improvement. It is used principally in racing and performance for speeding up the combustion of high speed engines. Moreover, such squish flow is not used in conjunction with the spark except in my U.S. Pat. No. 5,517,961, where it is used in conjunction with a high energy, flow-resistant spark to help spread the spark and speed up the bum.
SUMMARY OF THE INVENTION
In this patent application is disclosed an ignition and combustion system based on the interaction of two types of flows typically occurring orthogonally or at other angles to each other. One is a bulk flow located at the spark plug site at the time of ignition to interact (couple) to the spark discharge to direct and spread the spark, along arc runners if practical; the other is made up of impinging flows, which are directed towards each other as colliding flows which generate intense turbulence upon colliding, into which the spark discharges and resulting initial flame kernels can move in the form of flow-coupled-spark-discharges of the type disclosed in my U.S. Pat. No. 5,517,961. Preferably the colliding flows occur in a highly confined region or zone of the engine combustion chamber defined by the piston or other movable element nearing top center (TC) and the fixed walls of the combustion volume, made up, for example, of the engine cylinder wall and cyinderhead in a conventional piston IC engine. Preferably, the colliding flows occur in a combustion zone under the exhaust valve, or other high temperature zone of the combustion chamber, with the bulk flow occurring at one, two, or more individual or continuous edges of the turbulent zone to move and direct one, two, or more high energy flow-resistant spark discharges into the mixture turbulence to produce a very rapid and complete combustion of an air-fuel mixture without engine knock or other deleterious effect. In this way, very lean and high EGR mixtures can be burnt very rapidly at a high compression ratio without knock to produce high engine efficiencies and low emissions, especially low NOx emissions whose formation depends on both temperature and time, both of which are minimized in this application.
Preferably, but not necessarily, both flows, the bulk flow, BF, and colliding turbulence generating flows (CTF) are produced by the piston motion near TC, with the bulk flow occurring at the spark plug site and directed towards the region of the turbulence of the CTF. With the use of one spark plug and two valves, preferably the spark plug is located between the valves disposed preferably along or near a center diameter line of the engine cylinder. The spark plug may be located along a center line if bulk flow is present at the spark plug site, e.g. by placing the combustion chamber under the exhaust valve; or the spark plug may be placed offset of the valve center line at a high squish bulk flow region if the combustion chamber includes part or most of the region under both valves, either in the cylinder head or in the piston as has been disclosed in my U.S. Pat. No. 5,517,961. If two spark plugs are used, with one or two intake and one exhaust valve, more options are available for achieving BF and CTF. For example, the spark plugs can be disposed on either side of the exhaust valve under which is defined the combustion chamber and region of CTF, with two inward moving bulk flows (BFs) occurring at the two spark plug sites for two flow-coupled-spark discharges (FCSD), producing a more elongated combustion zone and even more rapid burning of the air-fuel mixture. Placing the combustion chamber under the exhaust valve reduces the engine's knock susceptibility and improves its lean bum capability.
In general, for conventional piston engines, the flows are produced by the piston motion near TC which induces extended squish flows which can be viewed as pairs of flows induced to move towards each other and collide to produce an elongated intense turbulence in the combustion zone, and one or more highly directed bulk flows which are directed to pass through the spark gap or other ignition region to form a flow-coupled-spark discharge (FCSD) which moves into, and feeds, the colliding turbulent flows to produce a very rapid and vigorous bum. This can be viewed as a colliding-flow-coupled-spark-discharge (CFCSD), versus simply an FCSD. It is made up of high energy, flow-resistant, flow-coupled-spark-discharges which move into, and/or produce initial flame kernels which move into, the high turbulence region (of small eddies) produced by colliding flows which homogenize the mixture and help spread the flame. In effect, CFCSD is a turbulent air-fuel mixture into which high energy spark discharges and/or flame kernels penetrate at a high directed speed spread under intense turbulence.
A preferred embodiment is one in which two valves are used with the spark plug in between the valves in a line approximately representing a diameter of the cylinder, with the combustion zone under the exhaust valve which is recessed and with the intake valve only slightly recessed so as to provide a region of high squish at the spark plug site. Intake valve opening preferably occurs at or very near TC, before or after TC, so as to require minimum intake valve recessing to not unduly compromise the squish flow at the spark plug site. Preferably the piston is flat or slightly cupped under the combustion zone, with thermal barrier coatings used to limit heat transfer to the piston and other parts of the combustion chamber.
In another preferred embodiment, the inlet air flow is used to reinforce the combustion process. Such an inlet flow can be a vertical vortex flow which reinforces one or more of the squish induced flows.
For the ignition, preferably triangular distribution spark with a peak amplitude above 200 milliamps (ma) is used, say 300 to 800 ma, operating in part in the flow-resistant arc discharge mode (versus glow discharge) which can sustain flow velocities of 20 meters/sec (m/s) or greater without spark segmentation, as disclosed in my U.S. Pat. No. 5,517,961, to produce a very fast ignition and combustion of the mixture.
In another preferred embodiment, the spark may be fired to the piston given the ability to operate the engin
Cohen Jerry
Perkins Smith & Cohen LLP
Solis Erick
LandOfFree
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