Internal-combustion engines – Charge forming device – Gaseous fuel and air mixer
Reexamination Certificate
1997-12-24
2001-01-30
Kwon, John (Department: 3747)
Internal-combustion engines
Charge forming device
Gaseous fuel and air mixer
C123SDIG001
Reexamination Certificate
active
06178952
ABSTRACT:
The present application claims priority under 35 U.S.C. 120 of PCT International application No. PCT/NL 96 00253, Publication No. WO 97/01701 designating the United States, filed Jun. 20, 1996.
BACKGROUND
1. Field of the Invention
A device suitable for supplying a gaseous fuel to an internal combustion engine, as well as an evaporator, a metering device, a processor and a pressure regulating unit suitable for use in such a device.
2. Description of Related Art
The invention relates to a device suitable for supplying a gaseous fuel to an internal combustion engine comprising combustion chambers, which device is provided with an evaporator and with a metering device, said metering device on an inlet side being in communication with an evaporating chamber disposed within said evaporator, and on an outlet side being provided with a main pipe, said main pipe after said metering device branching into a number of pipes connected to the individual combustion chambers.
The invention furthermore relates to an evaporator, a metering device, a processor and a pressure regulating unit suitable for use in such a device.
From NL-8600611 such a device is known with a pressure modulator
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located in the main pipe. The main pipe is connected to a branching device
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in which the main pipe branches in a number of pipes
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connected to the individual combustion chambers. The function of the pressure modulator
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is to prevent that the pressure fluctuations in the inlet manifold influence the stability of the pressure controller/evaporator. Hereby deviations between the desired total gas flow and the actual total gas flow are prevented. Such variations could obviously occur as a result of variation in the pressure line.
The systems as described in NL-A-8600611 will, however., suffer from a poor distribution over the various cylinders as no specific measures are taken in the distribution lines and as a result of differences in the flow resistances of the individual pipes and of dynamic pressure differences in the inlet manifold.
The object of the invention is to provide a relatively simple device, by means of which gas can be supplied to an internal combustion engine in a metered manner whereby an optimalisation of the equal distribution of the total gas flow over the different cylinders of the combustion engine is obtained.
With the device according to the invention this objective is accomplished in that each pipe is provided with a fixed predetermined local/constriction, across which at least 85% of the pressure drop from the division of the main pipe into the individual pipes to the combustion chambers takes place, whereby the differences in the flow resistances of the local constrictions of the individual pipes are 5% at most.
Dynamic pressure variations which occur in the inlet manifold near the combustion chambers and which depend inter alia on the number of revolutions and the load and the location of each combustion chamber cannot penetrate into the pipes of the device as a result of the damping effect of the local constrictions. Differences in the distribution of the gas flow, which will occur in the device known from the aforesaid Dutch patent application as a result of this disturbance, are practically fully adjusted by the local constrictions, therefore. In addition to that the influence of variations in the length and the curvature of the pipes between the main pipe and the combustion chamber has become negligibly small.
Because the gas supply is distributed precisely proportionally over the various combustion chambers, the exhaust gases of the various combustion chambers will have substantially the same composition.
It is noted that with a device disclosed in Dutch Patent Application NL-A-9002862 gas in liquid or gaseous form is evaporated in the evaporator and then metered and distributed over the various combustion chambers of the internal combustion engine by means of the metering device. The metering device is to this end provided with a number of passages, which number corresponds with the number of combustion chambers. The passages need to be manufactured with relatively great precision in order to obtain a proper metering as well as a proper distribution. A drawback of such a device is that the metering device is relatively complicated as a result of this. In addition to that the device is provided with a number of pressure regulating units, which number corresponds with the number of combustion chambers, which makes the device relatively costly.
It is furthermore noted that from U.S. Pat. No. 3,799,124 a device is known wherein the flow resistance of a pipe can be changed, for example by means of an adjusting screw. This device has a number of serious drawbacks In practice it is not possible to realize a proper adjustment for each individual combustion chamber. The air/fuel proportion is not measured individually for each combustion chamber.
Thus there is no feedback information with regard to the adjustment of the adjusting screw and the result achieved therewith. Furthermore the adjusting of the various adjusting screws is a relatively time-consuming activity. With the known device the flow ratio of the pipe is changed by means of the adjusting screw, in such a manner that differences in the length and curvature of the pipes are adjusted for. From the aforesaid US patent it is not known, however, to adjust for a comparatively more important aspect, namely the dynamic pressure variations in the inlet manifold at the combustion chambers.
It is noted that U.S. Pat. No. 4,386,593 describes a device with adjustable valves
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in each hose. However, as has been indicated above with respect to U.S. Pat. No. 3,799,124, in practise it will hardly be possible to realise an adjustment which meets the requirements that are set by the latest regulations with respect to emission. Furthermore such adjustment is only possible with special test equipment and is very time consuming.
SUMMARY
One embodiment of the device according to the invention is characterized in that the outlet side of the metering device is connected to a pressure regulating chamber disposed within the evaporator, which pressure regulating chamber is separated from the evaporating chamber by a movable membrane, whereby the supply of liquid gas to the evaporating chamber can be regulated by means of said membrane.
The membrane may be spring-biased. As long as the (possible) spring pressure and the gas pressure in the pressure regulating chamber are greater than the gas pressure in the evaporating chamber, the supply of for example liquid gas to the evaporating chamber will remain open. As soon as the pressures in both chambers are equal, the gas supply is shut off. When the pressure after the local constrictions increases, the pressure before the local constriction will also increase. As soon as this pressure becomes greater than the pressure after the metering device, the pressure after the metering device will increase as well. When said pressure increases, the pressure in the pressure regulating chamber will increase and the gas supply to the evaporating chamber will be opened further, as a result of which more gas will flow into the combustion chamber and the gas pressure will increase until the pressure in the evaporating chamber and consequently before the metering device is so high that the pressure across the metering device will remain substantially constant and gas is supplied to the combustion chambers through the local constriction.
Another device according to the invention is characterized in that the metering device is provided with a controllable passage, whereby the width of said passage may be controlled in dependence on a petrol fuel requirement of the internal combustion engine present in a processor.
In this manner an efficient use is made of data with regard to the petrol fuel requirement of a petrol engine, which data is already present in a processor of a vehicle. With the device known from Dutch Patent Application NL-A-9002862 all kinds of data are measured by means of sensors and process
Hessels Johannes L. L.
Kersten Antonius H. G.
Lammerts Johannes J. A. M.
Indopar B.V.
Kwon John
Skjerven Morrill & MacPherson LLP
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