GB2116727A - A device for detecting fuel differences in multigas I.C. engines - Google Patents

Abstract

A device for detecting fuel differences in multigas I.C. engines comprising a housing 1 provided with a fuel inlet 3, an air inlet 2 and an outlet 4 to the engine manifold vacuum, said housing comprising a means adapted to detect changes in density of the incoming gases due to composition changes e.g. to detect whether butane or propane is being supplied as fuel. Fuel impinges on a vane 8 of a lever 6, 7, and air impinges on vane 9 of the lever. Should the composition of the incoming gas charge, the resulting density change will cause rotation of the lever to cause alteration of the engine tune e.g. by varying the carburetter setting. The fuel gas may act on a vane of a one armed lever which is biased by a spring. In an alternative embodiment the air and fuel act on multivaned rotors which are coupled together. <IMAGE>

Description

SPECIFICATION A device for detecting fuel differences in multigas I.C. engines The invention relates to a device for the detection of fuel differences in multigas l.C. engines and, more in particular, in automobile l.C. engines. The term "I.C." is used for "internal combustion". In view of a.o. the energy crisis, attempts have been made to feed l.C. engines with gaseous fuels, for example liquefied petroleum gases (LPG).

At present l.C. engines, which are intended either by design or by modification to be fuelled by a gaseous fuel, tend to be "set-up" for a particular fuel on which they run well. In order that l.C. gas engines will run well, several specific requirements should be met, for example as to density of the fuel, suitable gas carburettors or fuel injection devices, etc. In particular,thefuel density should notvarytoo much.

However, in different countries and even in different areas within a country the nature and composition of fuel gas available may vary. For example, in one country or area propane is used as a fuel, whereas in other countries or areas butane is used. An example of a "propane-country" is the Netherlands. An example of a "butane-country" is France. If a gas engine which has been set up for a particular fuel, is used in several areas or countries, such a situation will lead to substantial loss of engine power and decrease in accelerating ability.

It will be clear that it is very desirable to have l.C.

engines which operate on all the different fuels available in order to avoid the above-mentioned problems. Further a very special problem appears in that the change in air-fuel ratio, which occurs when a different fuel (i.e. a different density) is used on settings designed for an original one, can produce an unacceptable change in the carbon-monoxide (CO) content of the engine's exhaust gases. For example, an engine set-up to run optimally on propane gas and giving a CO-reading of 0.2, when run on butane gas gives a reading of 2.25.

It is therefore an object of the present invention to produce a device adapted to detect fuel density differences due to composition changes in multigas l.C. engines, said detection being used to modify the engine tune accordingly.

It is another object of the invention to provide a device adapted to be used for varying the air-fuel ratio in order to prevent unacceptable changes in the CO-content of the exhaust gases.

It is still another object of the invention to provide a device adapted to be used in fuel pollution control work.

It is still another object of the invention to provide a device adapted to detect fuel density differences in multigas l.C. engines in order to be able to be used with electronic control systems.

The invention therefore provides a device for detecting fuel differences in multigas l.C. engines comprising a housing provided with a fuel inlet, an air inlet and an outlet to the engine manifold vacuum, said housing comprising a means adapted to detect changes in density of the incoming gases due to composition changes. It will be clear to those skilled in the art that the incoming gases are fuel and air.

The present invention has been based upon the fact, that various fuel gases have differences in densities. For example, propane gas has a specific density of 1.55 (at 60 F) whereas butane gas has a specific density of 2.08 (at 60"F).

The differences in densities of various fuel gases can be detected and can be used to modify the engine tune. For example, the air and fuel can each act on an extremity of a pivoted lever, the position of which can for example adjust the fuel/air ratio. This adjustment can be carried out by any means suitable forthe purpose, for example mechanical means.

According to advantageous embodiments of the invention a rotating means such as a pivot provided with at least one arm or a rotor having been provided. The said means are rotated in a suitable way by the incoming gaseous fuel or air and the rotation thus obtained is used in order to achieve the above objects.

The invention will now be described by way of example in more detail with reference to the accompanying drawings, in which: Figure 1 represents schematically an example of an embodiment of the device according to the present invention; Figure 2 represents schematically another example of an embodiment of the device according to the present invention.

With reference nowtofigure 1 a housing 1 is shown. The housing 1 of any suitable material has been provided with an air inlet 2 and a fuel inlet 3.

Further an outlet 4 to the engine manifold vacuum is shown. It will be clear to those skilled in the art that the air inlet, the fuel inlet and the outlet 4 can have any shape suitable for the purpose and may be fitted at any suitable position on the said housing. The flow through these orifices could for example be induced by a pump (not shown) either separately or in addition to the manifold vacuum.

The housing 1 comprises a rotating means such as a pivot 5 having two arms 6 and 7 respectively. The pivot is arranged in the housing 1 in any way suitable for the purpose (not shown). The arm 6 has attached a vane 8, against which a flow of fuel gas is impinged. The second arm 7 carries a second vane 9, against which a flow of engine intake air is impinged.

Using intake air on the second arm improves the usefulness of the device according to the invention even further since ambient temperature and altitude can automatically be compensated for. With a mean gas density and air density the vanes will take up a mid position.

If changes in density of the incoming gas or gases due to composition changes occur, a rotation of the arm 6 about the pivot 5 is caused, represented by the arrow "A" and this rotational displacement can be detected by any means suitable for the purpose (not shown for reasons of clarity) and can for example be used to vary the setting of an associated gas carburettor (not shown, since known per se). This can for example be done by a suitable transducer such as a capacitance or photoelectric means. In this way the engine's electronic injection or gas supply system can be influenced.

It will be appreciated that the invention is not restricted to pivots having two arms, each arm carrying a vane. It is for example also possible to use a pivot having two arms, one arm carrying a vane, against which the fuel gas flow is impinged, the other arm being spring-loaded (not shown).

Figure 2 shows an alternative embodiment of the present invention.

A housing 1 a with a fuel inlet 3a, an air inlet 2a and an outlet 4a to the engine manifold vacuum are again shown. This embodiment comprises two sliding pivots 10 and 11 respectively. Each pivot has been provided with arms 12 and 13 respectively.

Each arm 12, 13 has been connected in an eccentric way to rotating means such as rotors 14 and 15 respectively. The reference numbers 16 and 17 indicate the rotation axes of the rotors 14 and 15 respectively. In an advantageous embodiment the rotors are finned rotors.

The operation of the device is in principle the same as described with respect to figure 1: the density differences in incoming fuel or air due to composition changes cause a rotation of the (finned) rotors and this rotation provides an (eccentric) movement of the arms 12, 13 respectively which causes a sliding movement of the pivots 11,10 respectively.

The said sliding movement can be used by any means suitable for the purpose (not shown) to tune the engine orto prevent an unacceptable change in CO-content of the exhaust gases. For these purposes similar means as described in the above can be used.

In another embodiment of the invention (not shown) the rotation of the rotor can be used directly (without using an eccentric and/or sliding pivots) in orderto provide the tuning of the engine etc.

It will be appreciated that the orientation of the vanes, or in the case of the (finned) rotors, the links should be such that the mechanism readily takes up an equilibrium position related to the relative flow and densities of the air and gas streams. Further the mass flow of mixture through the device should be some quantity less than that required for the minimum operating speed and load of the engine e.g.

idling for a road vehicle.

It will be appreciated that the invention is not restricted to (finned) rotors; any suitable rotating means can be used.

Various modifications of the invention will become apparent to those skilled in the art from the foregoing description and accompanying drawings.

Such modifications are intended to fall within the scope of the appended claims.

Claims (13)

1. A device for detecting fuel differences in multigas l.C. engines comprising a housing provided with a fuel inlet, an air inlet and an outlet to the engine manifold vacuum, said housing comprising a means adapted to detect changes in density of the incoming gases due to composition changes.

2. The device as claimed in claim 1, wherein the said density detection means is connected to a pivot means in order to vary the setting of an associated gas carburettor.

3. The device as claimed in claims 1 or 2, wherein the said density detection means comprises a rotating means against which a flow of incoming fuel gas is impinged.

4. The device as claimed in claim 3, wherein the said rotating means comprises a pivot with at least one arm.

5. The device as claimed in claim 4, wherein the said arm has attached a vane, against which the said flow of incoming fuel gas is impinged.

6. The device as claimed in claims 4 or 5 comprising a second arm.

7. The device as claimed in claim 6, wherein the said second arm is spring-loaded.

8. The device as claimed in claim 6, wherein the said second arm has attached a vane, against which a flow of incoming intake air is impinged.

9. The device as claimed in claim 3 comprising a rotating means, against which a flow of incoming intake air is impinged.

10. The device as claimed in claims 3 or9, wherein the said rotating means is a rotor.

11. The device as claimed in claim 10, wherein the said rotors are provided with fins.

12. The device as claimed in claims 10 or 11 comprising two sliding pivots provided with arms and wherein the said arms are connected to said rotors in an eccentric way.

13. Device substantially as claimed in the specification and/or represented in figure 1 or 2 of the accompanying drawings.