Internal-combustion engines – Charge forming device – Auxiliary air or gas used to inject fuel
Patent
1991-10-10
1993-05-04
Argenbright, Tony M.
Internal-combustion engines
Charge forming device
Auxiliary air or gas used to inject fuel
123531, 2395851, 25112916, F02M 6908, F02M 5102
Patent
active
052072053
DESCRIPTION:
BRIEF SUMMARY
The subject of the invention concerns a device for the injection of fuel into the suction pipe of combustion motors. The device belongs to the category of injection systems with air-assisted fuel diffusion. The fuel is metered by means of one or more electromagnetic values and is then transported with the assistance of air to the individual injection locations via small diameter conduits. In addition, a suitable air pump for the generation of pressurized air is described, which functions in conjunction with the fuel injection device and is driven directly by the combustion motor itself.
OBJECTIVE OF THE INVENTION AND STATE OF THE ART
The basic design of a device for fuel injection with air-assisted fuel diffusion is familiar, for instance from DE-OS 2920636 (Emmenthal et. al.). In the referenced application no detailed descriptions for construction of the injection device are made.
A practically useful design example of such a device is described in U.S. Pat. No. 4,708,117. The electromagnetic valve of this device features a flat valve seat with an annular channel. By means of the annular channel very good precision of fuel distribution to the individual cylinders of the combustion motor is achieved. However, the electromagnetic metering valve must be built with a high degree of precision, causing difficulties in manufacturing. Despite the high precision requirements in manufacturing, the sealing capacity of the valve seat is often unsatisfactory. Furthermore, the speed of the opening and closing movements, and their reproducibility, is not always adequate for the desired metering precision in the case of this valve. Alternatively, the use of a ball-type valve obturator has been proposed. With the use of this type of obturator it becomes necessary to arrange the individual metering nozzles in close proximity to each other. This in turn leads to mutual interaction between the flows to the individual nozzles. This type of nozzle arrangement below a ball-type valve obturator results usually in unsatisfactory precision of fuel distribution.
It is furthermore state of the art, to assign an individual injection valve to each cylinder of the combustion motor, and to equip these injectors with devices for the air-assisted fuel diffusion. The injection valves are then usually supplied by means of a fuel manifold which is located above the injection valves. This results in high costs and a rather undesirable additional equipment height above the individual valves. In addition, mounting such an injection system is complicated due to the fact that a multiplicity of individual elements and connections results. Because of the relatively large distance of the injection nozzles, strong pressure variations arise inside the individual valves, and, because of the impaired perfusion of the individual valves with fresh fuel, hot-start problems occur frequently.
Air consumption of this type of injection device with air assisted fuel diffusion decreases with increasing amount of injected fuel. This behavior is attributable to the fact that, as the amount of injected material increases, fuel progressively blocks the supply lines, impeding the air flow. This feature considerably complicates adaptation of the rated performance of an air pump to the rated requirements of the injection device.
For state of the art systems, an electrically driven air pump is used to generate the compressed air. The electric drive for the air pump causes increased manufacturing costs. Therefore, it has been desirable to use an air pump which is directly mechanically, driven by the combustion motor itself. The use of such pumps has already been proposed several times. The state of the art pumps, however, feature an extraordinarily unfavorable response curve for the amount of air delivered. With directly driven mechanical pumps, the amount of air delivered increases approximately linearly with the number of revolutions, on the other hand, the amount of air required by the injection device decreases with increasing number of revolutions. With state of
REFERENCES:
patent: 4224915 (1980-09-01), Emmenthal et al.
patent: 4572436 (1986-02-01), Stettner et al.
patent: 4610425 (1986-09-01), Kelly
patent: 4708117 (1987-11-01), Mesenich et al.
patent: 4958773 (1990-09-01), Stettner et al.
Argenbright Tony M.
Boller George L.
Siemens Automotive L.P.
Wells Russel C.
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