Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
1999-03-11
2001-05-15
Morris, Lesley D. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C251S282000
Reexamination Certificate
active
06230991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a gas valve with electromagnetic actuation, in particular to a fuel-injection valve for gas engines, which includes a sealing member which is actuable by way of the armature of a controllable electromagnet between a or each fuel supply and a or each fuel outlet and with at least one closure spring acting on the sealing member.
2. The Prior Art
In conventional gas engines based on the Otto principle, the fuel gas is admixed in the intake line and is then supplied to the cylinders. Control valves and static mixers, for example, are used in this procedure. However, these systems are too unwieldy for systems with electronic fuel injection. Gas nozzles switched by way of magnets and which meter the fuel and produce combustible mixture in the entire supply system have been used. For use in commercial vehicles, and in particular in the case of stationary gas engines, the excessively small throughflow cross-sections in the case of conventional gas valves have made it necessary to bunch together typically up to twelve of these gas valves in order to achieve adequate cross-sections (corresponding to a conventional central injection).
For the purposes of improved controllability, improved fuel use and more advantageous pollutant emission, however, systems are preferred which operate with the so-called multi-point injection or ported-gas admission and which supply each cylinder individually with its combustible mixture by way of separate injectors or valves. In this case, the quantity of gas supplied is controlled typically by way of the differential pressure, i.e., the difference between the supercharging pressure in the gas line and the gas pressure in the cylinder supply. In this case, the valves remain open over the greater part of the intakes stroke and the time control is carried out with respect to individual adaptation of the quantity of gas supplied to each individual cylinder. The valves known at present, however, are unsuitable for use in systems of this type, since they have insufficiently large throughflow cross-sections of at most 4 to 5 mm
2
. On the other hand, however, the requirement of a larger throughflow cross-section involves increasing difficulties in achieving the brief and precise actuating times required and the high degree of precision in metering which is necessary. In addition, in the case of large valve cross-sections large and very powerful electromagnets have been necessary until now in order to move the large valve bodies against the action of the closure-spring arrangement and the differential pressure at the sealing member.
The object of the present invention has thus been to provide a gas valve which has—at the same time—a large throughflow cross-section, exact operating and response times as short as possible and a low power consumption and which is also suitable for use in multi-point or ported-gas admission systems and in the case of supercharged engines in particular in the case of gas engines for commercial vehicles or stationary gas engines.
SUMMARY OF THE INVENTION
This object is attained according to the invention in that at least one device for compensating the differential pressure acting upon the sealing member is connected to the sealing member. In this way, the pressure difference—adversely affecting the precision of the actuating and control times of the valve—between the side of the sealing member acted upon by the fuel gas under pressure and the outflow side under lower pressure is compensated and only the precisely determinable design of the closure spring and the electromagnet is decisive for the opening and closing of the valve. By compensating the differential pressure the electromagnet for actuating the valve can also be made smaller, since only the force of the closure spring and the mass inertia of the closure arrangement have to be overcome.
In one preferred embodiment, the device for compensating the differential pressure is in the form of at least one compensating piston which is acted upon with the fuel pressure in the opening direction of the valve, and gas passages are provided from the fuel outlet and/or outflow chamber to the opposite side of the compensating piston. In this way, the desired pressure compensation should be achieved at the sealing member in a structurally simple and reliable manner by the direct utilization of the pressure of the fuel to be controlled by the valve. The pressure in the compensating chamber is in turn set by way of the gas passages so as to be equal to the pressure in the fuel outlet and the outflow chamber, so that in each case the differential pressure at the sealing member is compensated by a differential pressure of equal magnitude and orientated opposite thereto at the compensating piston, and the resultant of the closure-spring force and the magnetic force is exclusively decisive for both the opening and the closure of the valve, and the precision of the valve actuation is not adversely affected by different pressure ratios in the system.
In order to ensure a relatively simple design of the valve, the compensating piston is guided displaceably in the valve housing in a sealed manner, and is clamped between the or each closure spring and the sealing member. Additional cylinder chambers or guides for the compensating piston can thus be omitted, and the production of the valve can be kept relatively simple and economical. The pressure of the fuel gas is used to counteract the closure spring and thus to form a compensation for the pressure upon the sealing member.
A structurally simple design, which causes the compensating piston to act directly upon the sealing member, is provided in accordance with a further embodiment of the invention when a central pin is inserted between the armature plate and the sealing member, and the compensating piston is formed by a projecting disc axially displaceable on the said central pin.
A simple and highly advantageous embodiment is provided in that at least one gas passage is formed by an opening in the sealing member and/or a bore in the central pin. In the first place, bores or similar structures which are complicated to produce in the valve housing are avoided, and, in addition, the bore in the central pin reduces the weight thereof, and this is advantageous for the speed of actuating the valve and the design of the electromagnet.
In order to achieve sufficiently large opening cross-sections and to be able to actuate the cross-sections in a rapid and precise manner independently of the existing pressure ratios, in accordance with a further feature of the invention the gas valve is constructed in the form of a flat-seat valve with a flat valve seat and a sealing member with at least one flat sealing face facing the valve seat, and the compensating piston bounds an annular space above the sealing member, into which the fuel supply opens, preferably radially.
The invention will be explained in greater detail in the following description with reference to an embodiment illustrated in the accompanying FIGURE.
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patent: 5108071 (1992-04-01), Hutchings
patent: 5641148 (1997-06-01), Pena et al.
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patent: 2250801 (1992-06-01), None
Rein Karl
Steinruck Peter
Dykema Gossett PLLC
Hoerbiger Ventilwerke GmbH
Morris Lesley D.
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