DESCRIPTION

The present description relates generally to a combined ignition and supply system for internal combustion engines and, more particularly, to a combined carburettor ignition and fuel supply system for motorcycles.

The fuel supply systems for endothermic petrol engines can be divided into two groups:

1. traditional carburettor systems, in which air and petrol are blended inside the carburettor;

2. electronic injection systems (direct or indirect), in which the flow of petrol is regulated by an injector and the flow of air is regulated by a butterfly element.

In the electronic injection systems, to date those most frequently used to limit pollutant emissions, the use of a pressure sensor ("manifold absolute pressure sensor" or MAP sensor) on the aspiration duct to assess the amount of air entering the cylinders and, consequently, gauge the corresponding amount of petrol to inject is widespread.

In a typical example of a traditional carburettor system, the fuel supply and ignition are achieved rather by means of the following components:

• carburettor;

• capacitor discharge ignition (CDI ) ;

· butterfly valve position sensor ("throttle position sensor" or TPS) . - -

In this type of system, the ignition commands the spark plug with variable advance to optimise combustion. The variable advance map, for basic systems, depends on the number of revs, while for more sophisticated systems, it also depends on the opening of the throttle.

The opening of the throttle can be measured constantly with a TPS ("throttle position sensor") , or in ON/OFF mode, using a switch which detects a certain percentage of opening. The advance maps may therefore be two-dimensional (depending on the number of revs only) or three-dimensional (depending on the number of revs and the throttle position) .

In the motorcycle sector, due to increasingly strict anti-pollution laws, carburettor fuel supply systems are being gradually replaced by injection fuel supply systems which are better able to adopt exhaust fume post-treatment systems (catalytic exhausts) . Injection fuel supply systems also allow better management of the combustion blend parameters by the engine, reducing consumption and forming exhaust fumes that are easier for the catalyser to process.

Injection fuel supply systems also allow better control of the blend in every engine running condition. Therefore the engine runs more smoothly at every speed and responds better when accelerating without any hesitation .

On the other hand, injection fuel supply systems have higher production costs than carburettor systems and are harder to repair. Consequently, the carburettor is still commonly used in today' s production of motorcycles, especially in two-stroke engines, both for - -

standard circulation and competitive use.

The general aim of the present description is therefore to make available a combined ignition and supply system for internal combustion engines that is able to solve the problems mentioned above in relation to the prior art in a very simple, economic and particularly functional way.

In detail, one aim of the present description is to make available a combined ignition and fuel supply system for internal combustion engines which permits an improvement of consumption and/or performance compared to similar known systems.

Another aim of the present description is to make available a combined ignition and fuel supply system for internal combustion engines which permits variation of the ignition advance in relation to the engine filling conditions.

The above aims are achieved by constructing a combined ignition and fuel supply system for internal combustion engines as presented in claim 1.

Further features of the above combined ignition and fuel supply system are highlighted in the dependent claims, which are an integral part of the present description .

The features and advantages of the above combined ignition and fuel supply system for internal combustion engines will become more evident in the following description, made by way of a non-limiting example, with reference to the drawings annexed, wherein:

figure 1 is a perspective view of one embodiment of a combined ignition and fuel supply system for internal combustion engines; - -

figure 2 is a view from above of the combined ignition and fuel supply system for internal combustion engines shown in figure 1 ;

figure 3 is a cross-section view from above of the combined ignition and fuel supply system for internal combustion engines shown in figure 1 ;

figure 4 is a table containing examples of ignition advance values depending on the pressure measured in the aspiration manifold and on the engine rpm; and

figure 5 is the three-dimensional representation of the table shown in figure 4.

With reference to the figures, a preferred embodiment of the combined ignition and fuel supply system for internal combustion engines is shown. The engine is preferably a one-cylinder model, though this does not exclude the application of the system to engines with two or more cylinders.

The combined ignition and fuel supply system comprises a blending/dosing device 10, such as a carburettor, equipped with an entrance duct 12 for the combustive agent, usually air, an entrance duct 14 for the fuel and an exit duct 16 for the fuel-combustive agent blend. The exit duct 16 is hydraulically connected to an aspiration manifold 18 which introduces the fuel-combustive agent blend into the cylinder 20 of the engine. The blending/dosing device 10 is internally equipped with a valve, which may be a butterfly valve or a shutter valve depending on the type of device, used to regulate the flow of combustive agent (air) to deliver into the aspiration manifold 18.

In the case of engines supplied with two separate . .

types of fuel, such as petrol and LPG or petrol and methane, only one of the fuels (petrol) is supplied through the entrance duct 14, while the other fuel (methane or LPG) arrives together with the combustive agent through the relative entrance duct 12. In other words, in engines supplied exclusively with petrol, the blending/dosing device 10 (carburettor) works as a regulation valve and as a blender, while in engines supplied with two types of fuel, the blending/dosing device 10 (carburettor) works as a regulation valve only .

The combined ignition and fuel supply system also comprises an ignition unit (not shown) . Preferably, the ignition unit is a capacitor discharge ignition (CDI) . The combined ignition and fuel supply system may, lastly, comprise, in a manner in itself known, all those components that allow it to run correctly, meaning an energy source (magnet or accumulator) for the ignition unit, a fuel tank, a fuel pump, one or more filters for the fuel and for the combustive agent, and so forth.

According to the invention, downstream of the blending/dosing device 10 and upstream of the cylinder 20 and preferably on the aspiration manifold 18, there is at least one pressure sensor 22 which is used, that is to say is suitable for, identifying the pressure value of the fuel-combustive agent blend in said aspiration manifold 18 and for optimising fuel consumption, varying the advance depending on the pressure value in the aspiration manifold 18 and on the engine revs. Preferably, the pressure sensor 22 is an absolute pressure sensor ("manifold absolute pressure - -

sensor" or MAP sensor) .

The pressure sensor 22 is operationally and electronically connected to the ignition unit. The ignition unit is equipped with appropriate software configured to receive the incoming signal from the pressure sensor 22 and to use said signal to correct the ignition advance with the aim, among others, of reducing fuel consumption and/or improving performance.

The advance map implemented by the ignition unit is, therefore, three-dimensional (figure 5) and depends both on the rpm of the engine and on the pressure measured in the aspiration manifold 18 by the pressure sensor 22.

In this way, it has been seen that the combined ignition and fuel supply system for internal combustion engines of the type described above achieves the aims highlighted earlier.

The combined ignition and fuel supply system for internal combustion engines thus conceived may be subject to numerous modifications and variants, all falling within the same innovative concept; moreover, all the details may be replaced by technically equivalent elements. In practice any materials, forms and dimensions can be used depending on technical requirements.

The scope of protection of the invention is therefore defined by the annexed claims.