Swirl injector for internal combustion engine

Details Swirl injector for internal combustion engine Swirl injector for internal combustion engine

2003-01-27

2004-11-30

Argenbright, Tony M. (Department: 3747)

Internal-combustion engines

Combustion chamber means having fuel injection only

Using multiple injectors or injections

C123S494000, C239S533120, C239S585100, C356S028500

Reexamination Certificate

active

06823833

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a swirl injector for an internal combustion engine, and particularly to a fuel injector for a direct injection engine, which may be either a spark injection gasoline engine or a compression ignition diesel engine, which imparts a swirling motion to the fuel during injection to improve injection characteristics and performance The swirl injector has novel characteristics which enable adjustment of the injector's spray pattern to the phase of the stroke cycle, and may be used with a novel on-board flow meter which provides feedback to the engine control unit for adjusting injection characteristics.
2. Description of the Related Art
In recent years there has been a renewed interest in direct injection gasoline engines due to the greater fuel economy that can be achieved with direct injection engines, both for the sake of the savings in fuel costs and for the reduction in greenhouse gases consequent on reduced hydrocarbon fuel usage. The majority of gasoline fuel injection engines still use either throttle body injection or port injection into the intake manifold. Efforts towards using direct injection in gasoline engines have been complicated by the difficulty in finding a fuel injector which is capable of producing a homogenous air-fuel mixture during early fuel injection for a full load and a stratified air-fuel mixture during late fuel injection for a partial load, by controlling a stratified air-fuel mixture over a wide range of operating loads, and by the need for a rapid and smooth switching system for switching between early and late fuel injection. See SAE Technical Paper 970540, “Development of Direct Injection Gasoline Engine”, Harada et al., February, 1997, and SAE Technical Paper 970541, “Development of Gasoline Direct Injection Engine”, Iwamoto et al., February, 1997.
On the other hand, diesel engines may use direct injection into the combustion chamber, injection into a precombustion chamber connected to the main combustion chamber, or injection into a swirl chamber connected to the main combustion chamber. Direct injection is used with most heavy duty, high-speed diesel engines due to its greater fuel economy. A precombustion chamber is used with most passenger vehicles because of the smoother combustion and lower noise level available, at the cost of decreased fuel economy. A swirl chamber increases fuel economy over a precombustion chamber, but requires more precise machining, engineering, and matching of components. Fuel injectors for diesel engines were largely mechanically actuated and controlled until the 1980's. With the advent of concerns about emission controls and the development of automotive electronics, diesel engines now use electronic control modules or units to control the metering and timing of fuel delivery, although actuation of the injector plunger may still be done mechanically to develop the high injection pressures needed. A representative example is the fuel injector used in the Detroit Diesel Series 60 engine, described in
Diesel Technology
, Norman et al., pp. 510-512 (Goodhart-Willcox Company, Inc., 2001), in which a cam activated rocker arm depresses the injector plunger, raising the fuel pressure to unseat the needle valve, while fuel metering is controlled by a solenoid activated poppet valve. Smaller direct injection diesel engines may rely entirely on air swirl for mixing air and fuel in the combustion chamber, although some mechanical injectors for diesel engines provide for swirling the fuel as it leaves the injector.
Various solutions have been proposed to address these problems. U.S. Pat. No. Re. 34,527, issued Feb. 1, 1994 to Yoshida et al. describes a fuel injector having helical grooves. The patent is particularly directed to the feeder wire structure for the electromagnetic structure. U.S. Pat. No. Re. 34,591, issued Apr. 26, 1994 to Yoshida et al., shows the same injector as the '527 patent, but is directed to the submagnetic structure which controls the amount of lift.
U.S. Pat. No. 4,192,466, issued Mar. 11, 1980 to Tanasawa et al., shows a swirl injector for a diesel engine having a swirl chamber. U.S. Pat. No. 4,230,273, issued Oct. 28, 1980 to Claxton et al., describes an injector switchable between single point and multi-point injection systems. The embodiment shown in
FIG. 9
has helical grooves, but appears to be a pintle type not designed for dual injection. U.S. Pat. No. 4,365,746, issued Dec. 28, 1982 to Tanasawa et al. teaches a swirl injector having helical grooves which only extend through a radial angle of 60-100° around the needle body.
U.S. Pat. No. 4,629,127, issued Dec. 16, 1986 to Kawamura et al., teaches a fuel injector having grooves in the needle and adjusting the spray angle by adjusting the area of the gap between the valve needle and valve wall, the area of the grooves, and the angle of the grooves. U.S. Pat. No. 4,653,694, issued Mar. 31, 1987 to Noguchi et al., discloses a fuel injector in which the spray angle is adjusted by tapering the walls of the valve body and the needle, and by adjusting the lift height to vary with the load.
U.S. Pat. No. 4,721,253, issued Jan. 26, 1988 to Noguchi et al., describes a swirl injector which uses a straight passage between the needle and the valve body combined with a tangential groove to provide a spray with both angle and straight components. U.S. Pat. Nos. 4,974,565 and 5,058,549, issued Dec. 4, 1990 and Oct. 22, 1991, respectively, to Hashimoto et al., teaches a fuel injector with either tangential grooves or projections to impart swirl to the fuel spray, but uses two orifices in the nozzle to provide both wide and narrow spray angles.
U.S. Pat. No. 5,163,621, issued Nov. 17, 1992 to Kato et al., shows a fuel injector with multiple orifices in the nozzle arranged at different angles, and a needle valve tip having conical sections of different diameters, the injection angle and velocity being adjusted by varying the amount of lift. U.S. Pat. No. 5,163,621, issued Jul. 28, 1998 to Furuya et al., describes a swirl fuel injector having a conical needle tip with different diameter conical sections to adjust the spray angle by the gap between the tip and the valve seat.
U.S. Pat. No. 5,983,854, issued Nov. 16, 1999 to Machida et al., teaches a switching scheme for switching between uniform fuel mixture combustion injection on the intake stroke and stratified combustion on the compression stroke by a CPU and gate circuits which test what the load condition is. Japanese Patent No. 1,227,865, published Sep. 12, 1989 shows a fuel injector with a pilot nozzle and a main nozzle having multiple orifices, and a controller which times injections to overlap sprays from the pilot and main nozzles. Japanese Patent No. 3,033,422, published Feb. 13, 1991, teaches stratified combustion obtained by positioning of the spark plug relative to the spray pattern.
Japanese Patent No. 10,311,264, published Nov. 24, 1998; discloses an injector with helical grooves in the needle and a cylindrical element between the helical grooves and the conical tip which is termed a fuel regulator. Japanese Patent No. 11,082,229, published Mar. 26, 1999, shows a fuel injector similar to the Japanese '264 patent, but with a countersunk groove in the base of, the injector body to collect any fuel spit-back after injection.
Applicant is aware of a fuel injector designed by Applicant for Unisia Jecs Co. in 1997-98 and installed in Nissan Motor Company 2.2L engines beginning with April, 1998 with some common structural similarities to the fuel injector of the present invention. The basic construction and operational differences between the injector developed for Unisia Jecs and the fuel injector of the present invention are as follows:
1. The contact zone between the needle and the valve seat has been redesigned. The new design and sizing of the needle ball head, conical nozzle and outlet cylindrical part of the nozzle suppresses shock vibrations of the needle after valve closing to prevent post i

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