Internal-combustion engines – Means to whirl fluid before – upon – or after entry into... – Having multiple oxidant inlet means
Reexamination Certificate
2000-02-23
2001-08-21
Solis, Erick (Department: 3747)
Internal-combustion engines
Means to whirl fluid before, upon, or after entry into...
Having multiple oxidant inlet means
C123S301000, C123S302000
Reexamination Certificate
active
06276330
ABSTRACT:
TECHNICAL FIELD
A charge induction system for an internal combustion engine including air/fuel mixture intake ports adapted for developing a swirl motion of an air/fuel mixture.
BACKGROUND ART
Internal combustion engines that use a single intake valve and a single exhaust valve typically are not capable of producing the same intake port area as an internal combustion engine having a pair of intake valves. Thus, intake air/fuel mixture flow for a two-valve engine is less than the corresponding air/fuel mixture flow for a four-valve engine, even in those instances when the two-valve engine valve size has been increased to the maximum practical diameter. Further, the rate of valve opening for a two-valve engine, to achieve a flow comparable to the flow of a four-valve engine of equal displacement, is inherently greater than the rate of valve opening for a four-valve engine. Substantially more valve lift, therefore, is required to achieve the same flow compared to a four-valve engine.
One of the advantages of using a two-valve engine is the inherent ability of a two-valve combustion chamber, with offset intake port locations, to generate an air/fuel mixture swirl motion. This feature contributes to a fast and effective burn at low and moderate engine speeds. Because of this characteristic, better performance at the low speed end of the engine torque output curve can be achieved compared to a four-valve design.
In the case of a four-valve engine, the breathing characteristics at the top power output end of the engine speed curve is superior to the breathing characteristics of a two-valve engine, but low and mid-load range operating characteristics may be less than favorable compared to the corresponding characteristics of a two-valve engine.
One of the characteristics of a four-valve engine that causes inferior performance at the low speed of the engine power range is the difficulty in obtaining an effective swirl motion for the air/fuel mixture to achieve optimum mixing for efficient and rapid combustion. Although a tumble motion of the air/fuel mixture can be achieved in the case of a four-valve design, the effectiveness of the burning of the tumbling air/fuel mixture is less than the comparable effectiveness of a swirl motion of the air/fuel mixture. Even if a swirl motion can be achieved in a four-valve design (e.g., by using an auxiliary charge motion control valve to disable one intake valve port), a central location of the spark plug allows the swirl pattern to encircle the ignition source, which detracts from the effectiveness of the burn notwithstanding the presence of swirl.
DISCLOSURE OF INVENTION
It is an objective of the invention to design a four-valve combustion chamber for an internal combustion engine that is capable of taking advantage of swirl motion of the air/fuel mixture throughout the entire combustion chamber, thereby creating a more efficient charge burn. In this way, the advantages of a two-valve design in the low operating power range of the engine can be matched by a four-valve combustion chamber design without compromising the advantages of the four-valve design during operation of the engine at the high load range.
When the piston compresses the charge in which a swirling motion has been induced using the teachings of the invention, the effect of the swirl motion continues into the later stages of combustion. This is in contrast to an engine with the usual tumbling motion that is characteristic of a four-valve engine where the tumbling air/fuel mass tends to break down during the compression stroke.
By employing the teachings of the present invention, the stability of combustion of the air/fuel mixture is efficient enough to satisfy current cold-start engine emission standards. This is achieved without the necessity for using intake port throttling by a charge motion control valve to enhance the level of the charge motion.
According to a principal feature of the invention, a combustion chamber charge motion is achieved by using valve masks within the combustion chamber itself. A perimeter mask on the primary intake valve and an opposed bridge mask on the secondary valve create a swirl motion that persists throughout the extent of the combustion process, even into the later stages of the compression stroke. The masks direct the air/fuel mixture flow pattern at each of the two intake ports so that they work together to produce a coherent, tangential, spiral-swirl motion.
By using the improved combustion chamber design of the invention, it is possible to achieve a faster motion of the air/fuel mixture by reason of the swirl pattern that is established rather than a typical tumble flow pattern characteristic of a conventional four-valve combustion chamber. This achieves better mixing of the air/fuel mixture for a given time period.
Unlike the tumble flow pattern that is characteristic of a conventional four-valve combustion chamber, the swirl motion established by the design of the present invention makes it possible for the piston to compress the mixture without interrupting the swirl motion. In contrast, the tumble motion that is characteristic of conventional four-valve combustion chambers is interrupted as the piston begins to move upward in its compression stroke.
The improvements of the invention eliminate the so-called dead, isolated zones at the corners of the combustion chamber where the intake and exhaust valves meet the wall of the combustion chamber. The air/fuel mixture flow at those corners is disassociated from the main mixture flow in the combustion chamber when tumble motion characteristic of the conventional combustion chamber takes place. In contrast, the swirl motion that is characteristic of the present invention eliminates the separate air/fuel mixture flow patterns at the isolated zones. The entire combustion chamber is involved in the improved swirl motion, thereby improving mixing of the air and fuel. This results in improved combustion efficiency.
In practicing the present invention, the combustion chamber is provided with primary and secondary air/fuel mixture intake ports and at least one exhaust port. The combustion chamber may have only one exhaust port, as in the case of a three-valve design. An air/fuel intake manifold has intake flow passes communicating with the intake port.
The primary intake valve port is surrounded partly by a primary mask. A secondary mask surrounds a portion of the secondary port. The masks create an air/fuel flow passage through an intake valve opening whereby a charge swirl motion is established as the charge circulates about the axis of the cylinder. The secondary mask creates a charge motion swirl that complements the charge motion swirl created by the primary mask. The secondary mask creates a flow velocity component in the direction of the cylinder axis whereby the entire combustion chamber is filled with a moving air/fuel charge.
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Adamisin David Wayne
Bivins James Roy
Demitroff Danrich Henry
Lee John Clarence
Magnan Michael Bruno
Drouillard Jerome R.
Ford Global Technologies Inc.
Solis Erick
LandOfFree
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