FR3106628A1 - PROCESS FOR CONTROLLING A SIMULTANEOUS DUAL FUEL ENGINE - Google Patents

Abstract

Method of controlling a diesel fuel vehicle engine for approved data performance, provided with a computer, a diesel fuel supply system and a kinematic chain, characterized in that it consists of: - set up a complementary assembly for supplying said engine with a fuel gas - manage the supply of said engine through the computer with simultaneous bi-fuels, - to maintain the performance of said engine at a maximum level of equal performance, with approved performance. Figure to be published with the abstract: Fig. 1

Description

METHOD FOR CONTROLLING A SIMULTANEOUS DUAL-FUEL ENGINE

The invention relates to a method for controlling a dual-fuel, simultaneous engine.

There are internal combustion engines for passenger cars and utility vehicles using different fuels of petroleum origin, among which mention may be made of diesel fuels, gasoline and fuel gas, but also other gases used as fuels, natural gas or CNG, as well as gases from methanation. For the remainder of the description, we will use the term “fuel gas” to cover all of these gases.

These fuels have different properties and require different architectures. The gasoline engine has an ignition which causes an explosion of the fuel/oxidant mixture introduced into the combustion chambers of the cylinders when it is compressed. Progress has been made to ensure the most precise dosage possible in order to limit consumption. The disadvantage of this type of engine is to present a low torque and to present a limited robustness because the architecture does not require a reinforced engine block, these engines operating with an ignition like petrol fuel engines, the compression ratios being weak. A real problem is also that the cost of gasoline is high because this product is more refined than diesel for example. Such a vehicle rejects water, CO2, and solid combustion products, but in very small quantities, which is an advantage. These gasoline-fueled engines having engine blocks with lower masses warm up more quickly and are therefore more suitable for city, short, repetitive journeys. This fuel is rather reserved for high-performance vehicles, small or high-powered sedans, where lightness is an asset, in particular.

Diesel is a fuel which is less refined and which is currently reserved for heavy goods vehicles, utility vehicles and four-wheel drive type vehicles or even sedan vehicles which travel many kilometres. Indeed, the fuel is cheaper to produce in the refinery, without any tax, and will always exist as long as the gasoline exists and it is also necessary to be able to consume this fuel resulting from oil. Many criticisms have been voiced about the polluting nature of this type of engine due to the fact that combustion rejects water and CO2 but also fine particles harmful to health. Many advances have been made in this field with dosage, quantity and pressure controls in order to obtain the most complete combustion possible. In a diesel engine, the explosion is generated by self-ignition of the mixture when it is compressed beyond a certain value. Due to this high compression, the constructive elements of the engine are necessarily more resistant. One solution would be to reduce consumption and if progress has been made in this area, we are reaching a certain stagnation because we are approaching the intrinsic power of the fuel. The advantage of diesel engines is to give high torque to vehicles equipped with them, the engines provide this torque at lower speeds and generally a diesel engine runs at lower speeds, hence the interest in vehicles. professionals. The latest progress has focused on the exit of combustion gases with particulate filters in order to trap particles that would be harmful to health, but it has been found that the particles from these traps, also called catalytic converters, would be of even greater diameter. small and therefore even more easily ingested and going deep into the respiratory system.

Fuel gas is abundant and has a certain interest because of its cost and the fact that it is less polluting because it produces water and CO2 but extremely few fine particles. Fuel gas is essentially composed of butane, ethane, methane, propane, gases also used for domestic purposes in many countries. This fuel gas is used exclusively in certain engines. Nevertheless, the couple is less and the consumptions are important. Engines operating on fuel gas are engines with a diesel-type architecture.

Furthermore, another important data for vehicles is that they are manufactured by the manufacturers according to very strict standards which define all the other components according to engine power. Thus, the safety components such as the braking means, the types of tires, the steering, the suspension and damping means, are sized for a given maximum power and speed. Any modification involves passing a compliance check.

It has been found that utility vehicles, four-wheel drive vehicles running on diesel, can also operate on mixed fuels and in particular by injecting a non-negligible proportion of fuel gas, simultaneously with the diesel fuel. Due to the decrease in the quantity of diesel fuel, the emissions are therefore limited in a fully proportional manner. In addition, the dual fuel allows the torque generated by the diesel fuel to be retained. This is how we know a patent document, EP 3 014 091 perfectly describes an engine converted partly to fuel gas, therefore using a dual fuel. This modification consists of adding a tank of liquefied fuel gas, an injection line for this fuel gas, a controller/computer which ensures the metering of the fuel gas in relation to the diesel fuel in the mixture before introduction into the combustion chamber, thanks to injectors. The modifications are not very complex in the mechanical architecture of the engine, the modifications being essentially of a software order by the programming of the controller/computer.

Fuel modifications lead to changes in performance and in particular in torque, power and maximum speed of the vehicle whose engine has been modified to accommodate two fuels simultaneously. This obliges the owners to request approval from the supervisory authorities after this type of modification has been authorized in general. Indeed, any development, beyond the security manufacturer parameters initially planned, leads to compliance. The object of the present invention is to overcome this type of compliance problem.

The present invention is now described using examples which are only illustrative and in no way limit the scope of the invention, and from the accompanying illustrations, in which:

represents a performance curve comparing the engine torque of a diesel fuel used alone and of a dual-fuel diesel and fuel gas mixture.

represents a performance curve comparing the engine power of a diesel fuel used alone and of a dual-fuel diesel and fuel gas mixture.

The method according to the present invention relates to a method for controlling a simultaneous dual-fuel engine, diesel and fuel gas, in this case liquefied propane gas, LPG.

The engine according to the present invention is an internal combustion engine, in particular a utility vehicle, for example with four-wheel drive, operating on diesel fuel. This engine comprises the actual engine block of known type, a supply of diesel fuel by injection under very high pressure through injectors in the combustion chambers with which said engine block is equipped. The purpose of the injectors and the very high pressure is to micronize the diesel fuel to ensure an optimized mixture with the air introduced simultaneously to the diesel fuel in order to initiate the best combustion, providing the necessary oxygen, that is to say the oxidizer. The dosage, the precise moment of injection into the chamber, and more generally all the operating parameters of the engine in the acceleration, deceleration, stabilized speed, descent and ascent phases are taken into account to control the injection. The explosion in the chamber takes place spontaneously due to the very high compression which causes the diesel fuel to self-ignite. The pistons of each chamber are thus set in motion in turn according to the planned cycle as well as the entire kinematic chain.

In the case of the addition of a second fuel, fuel gas, the modifications consist in adding a separate fuel gas tank to the diesel fuel tank. The fuel gas is kept under pressure in the liquid state in the fuel gas tank and an additional fuel gas supply circuit is installed in order to be able to supply each chamber with fuel gas. Injectors are also provided to inject the necessary quantity of fuel gas into the chamber. This injection is also controlled by the computer according to the parameters entered in the control software. The modifications remain limited since they do not come in any way to interact with the engine block and the kinematic chain.

The results of such a modification are represented on the curves of FIG. 1 which show in dotted line the curve of the initial torque of the diesel fuel engine used alone. The maximum power is around 175 HP at around 2200 rpm. The torque then weakens almost constantly if the engine speed is increased, with a marked hole around 2700 rpm. It can be seen, on the second solid line curve which represents a dual-fuel supply, simultaneous, that the power is very clearly increased to about 190 HP with a constant up to 3100 revolutions/minute. The power is delivered in a perfectly progressive and constant way over a range of 1000 rpm, without gaps, very linear. This is extremely advantageous for utility vehicles, in particular during multiple starts and when the vehicle is also fully loaded. This is therefore particularly beneficial for the fuel consumption parameters because not only is the fuel gas cheaper, easier to manage from the pollution point of view, but it is thus possible to improve engine performance and make it more efficient, especially in the case of utility vehicles. The diesel/fuel gas ratio is of the order of 60% diesel and 40% fuel gas, in this case with liquefied propane gas LPG, in urban traffic and 50/50 in road consumption still with liquefied propane gas LPG . The consumption in the city is 6.48 liters of diesel fuel per 100 km and 6.00 liters of fuel gas per 100 km and the consumption on the road is 6.70 liters of diesel fuel per 100 km and 4.88 liters of fuel gas per 100 km. The general cost price is lower than the price of diesel fuel alone for much higher performance. We also see that the engine power follows the same performance increases.

The problem that arises is linked to the fact that the improved performance of the engine places the vehicle equipped with such a simultaneous bi-fuel supply system outside the standards for which it has been approved. Such a vehicle is therefore no longer compliant, it cannot be insured in the usual way, cannot be marketed in the usual circuits. The method according to the present invention consists in regulating the parameters of the engine, power and torque, in order to maintain them as much as possible at the approved parameters.

The method according to the present invention consists in providing a modification of the engine parameters in simultaneous bi-fuels at power and torque values at a maximum level of values equal to the maximum level of the values of the manufacturers' data, approved.

This process is based on an approach of the overcome prejudice type because generally, the owner who has the means leading to an improvement in performance wishes to use them in their entirety. The aim is thus to be able to benefit from the improvements linked to the use of simultaneous bi-fuels, for example to smooth the engine torque over a wider range of rpm. Similarly, the method also makes it possible to benefit from a better progressiveness of the torque and of the power. Above all, the method facilitates the management of microparticle emissions by limiting the consumption of diesel fuel while benefiting from its performance, which is a certain ecological progress. Indeed, the fuel gas essentially emits carbon dioxide and water vapor and an extremely limited rate of particles. At the same time, the cost of fuel gas with an equivalent energy capacity is lower, which compensates for the investment linked to modifications to the circuits, to the computer software and to the second tank.

The method consists in maintaining the initial performance values of a vehicle modified to be supplied with dual fuels diesel and fuel gas by modifying the parameters of the computer.

Claims (3)

Method for controlling a vehicle engine running on diesel fuel for approved given performance, provided with a computer, a diesel fuel supply system and a kinematic chain, characterized in that it consists of:
- set up an additional assembly for supplying said engine with a fuel gas
- manage the supply of said engine through the computer in simultaneous bi-fuels,
- to maintain the performance of said engine at a level of performance equal, at most, to the homologated performance. A method of controlling a diesel-fueled vehicle engine according to claim 1, characterized in that the fuel gas is liquefied propane gas. Method for controlling a vehicle engine using diesel fuel according to Claim 1, characterized in that it consists in injecting between 40 and 50% fuel gas into the total diesel/fuel gas mixture.