Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
1999-02-24
2001-02-06
Rivell, John (Department: 3753)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S129150, C251S359000, C239S585300
Reexamination Certificate
active
06182943
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas valve with electromagnetic actuation, in particular to a fuel injection valve for gas engines, which includes a sealing element, actuable by way of an armature of a controllable electromagnet, between a or each fuel inlet and a or each fuel outlet, and at least one closing spring acting on the sealing element.
2. The Prior Art
In conventional gas engines based on the Otto principle, the fuel gas is admixed in the intake port and 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 have therefore been used, these nozzles metering the fuel and producing a combustible mixture in the entire supply system. On account of the fact that the passage cross-sections are too small in conventional gas valves for use in commercial vehicles, it is necessary to bundle these gas valves, typically up to twelve of them, to obtain sufficient cross-sections (corresponding to the central injection which is customary in passenger vehicles). For this reason, gas engines, for example CNG (compressed natural gas), LPG (liquefied petroleum gas) or hydrogen engines, should also only be operated at present without supercharging, that is to say at atmospheric pressure, and typically achieve about 145 kW.
However, for improved controllability, better fuel utilization and more favorable pollutant emissions, preference is given to systems which operate with so-called sequential fuel injection (also known as multi-point injection or ported-gas admission) and supply each cylinder individually with its combustible mixture by way of separate injectors or valves. In this case, it is not necessary for a combustible mixture to be present in the entire intake system and the fuel injection mainly takes place during the intake cycle of the respective cylinder only. However, the valves known at present are unsuitable for use in such systems, since their passage cross-sections of not more than 4 to 5 mm
2
are too small, so that, per cylinder, two valves would be needed in atmospheric engines and three valves in supercharged engines. However, this is scarcely possible for structural reasons. On the other hand, the requirement for a larger passage cross-section entails ever-greater difficulties as regards obtaining the required short switching times and the high metering precision necessary, resulting in a low average pressure especially in the idle range and part-load range.
It is an object of the present invention to provide a gas valve which has very short switching and response times and at the same time a large passage cross-section, and which is suitable also for use in multi-point systems or ported-gas-admission systems and in supercharged engines, in particular in gas engines for commercial vehicles. An additional object is therefore to provide lightweight and yet stable sealing elements which combine the necessary rapid mobility, through small electromagnets, with a sure sealing action.
SUMMARY OF THE INVENTION
The invention provides a gas valve with electromagnetic actuation comprising at least one fuel inlet, at least one fuel outlet, a sealing element actuable by way of an armature of a controllable electromagnet and arranged between the or each fuel inlet and the or each fuel outlet, and at least one spring acting on the sealing element, wherein the gas valve is designed as a flat-seat valve with a plane valve seat and a sealing element with at least one plane sealing surface facing this valve seat. This design allows reliable and sure switching of high valve cross-sections of up to 10 mm
2
along with very small switching times, so that such a gas valve can be used to obtain the necessary control times of less than 1 ms with high precision, even at idle speed or part load.
According to a preferred feature of the invention, the fuel inlet opens radially into an annular space surrounding the valve seat below the sealing element. This produces good evening-out of the fuel flow upstream of the sealing element of the valve, and the amount of gas admitted is not adversely affected by fluidic phenomena.
A further object is achieved according to the invention with a gas valve with at least one sealing strip in the form of a closed curve, substantially circular, in that the sealing element has a number, proportional to the number of sealing strips, of peripheral ridges which follow the course of the sealing strips and of which at least two in each case are interconnected by at least one radial wall. These spaced-apart ridges cover substantially only the sealing strips and permit, however, the gas access to all these sealing strips. If in this case the passage cross-section is appropriately maximized, however, the material usage, hence the weight, and also the area of action for the differential pressure between the inflow and outflow side are minimized, while at the same time the grid structure of the sealing element provides a strength which sufficiently ensures the sealing action.
A design of high mechanical stability is provided if at least one radial wall, preferably all the radial walls, radiate from the center of the sealing element and interconnect all the peripheral webs.
In order to achieve an optimal compromise between mechanical strength and low weight, according to a preferred feature of the invention the axial height of the radial walls decreases from the center towards the edge of the sealing element.
For connection to an actuating element in a manner which is simple and favorable with regard to the application of the actuating forces, the sealing element preferably has a central bore for receiving an actuating element.
In order to ensure a connection to the actuating element in a manner which is as stable as possible and provide the possibility for coupling to additional components which influence the movement of the sealing element, the central bore is axially extended in the manner of a bush.
Advantageously, the sealing element is made as an injection-moulded part from plastics, preferably from a polymer, thereby ensuring together with a lightweight design also a very extensive reduction of the wear on the valve seat.
According to a further preferred embodiment of the invention, the valve seat is formed by at least two concentric sealing strips which define an annular passage cross-section which is covered by an annular sealing element, and gas passages are provided to both sealing strips, the gas passages to the outer sealing strip being formed by the or each fuel inlet and the annular space, and the gas passages to the inner sealing strip being formed by at least one preferably radial fuel inlet, cutouts in the actuating element, and a central cutout of the annular sealing element. Consequently, two ring areas are available for the fuel gas to flow through, thereby producing an enlargement of the passage cross-section by almost twice for the same switching and control times. Thus, for control times of less than 1 ms, valve cross-sections of around 15 mm
2
are possible even with only two sealing strips.
In order to take up the forces of the opening and closing system which act on the sealing element in such gas valves and to prevent deformations as a result of these forces acting in different regions of the sealing element, the armature acts on the sealing element by way of the actuating element. This ensures a large-area contact and force application, not giving rise to any deforming torques. However, by virtue of its large area of contact with the sealing element, the actuating element can at the same time also prevent deformation torques due to other system components and thus ensure the sealing action.
Preferably, the or each closing spring acts on the actuating element, preferably on a widened end piece provided for bearing on the sealing element. The closing force of the spring(s) is thereby applied to the sealing element over
Horvath Josef
Rein Karl
Steinruck Peter
Dykema Gossett PLLC
Hoerbiger Ventilwerke GmbH
Rivell John
Schoenfeld Meredith H
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