BRPI0914037B1 - METHOD OF STARTING A ENGINE TO COMBUSTION FED WITH A FUEL CONTAINING ETHANOL - Google Patents

Abstract

Method of Starting an Combustion Engine Fueled by an Ethanol-Containing Fuel The invention relates to a method for starting a combustion engine (1) powered by a first fuel which may contain ethanol, said engine being provided with an auxiliary system. including a reservoir (5) for a second fuel having a low ethanol content, in which the engine coolant temperature (1) is determined and the proportion of ethanol in the first fuel is determined, and characterized by: the engine coolant temperature is below a predetermined critical temperature and if the ethane ratio in the fuel is above a predetermined threshold value, the second fuel will be pre-introduced at the engine inlet (1) in response to an event occurring. demand, starting the engine.

Description

METHOD OF STARTING A COMBUSTION ENGINE FED WITH F

A FUEL CONTAINING ETHANOL ”

The present invention claims the priority of French Patent Application No. 0857152 filed on October 22, 2008 whose context (specification, 5 drawings and claims) is hereby incorporated by reference.

The invention relates to the starter field of combustion engines running on fuel containing ethane. These engines are often referred to by the name «Combustível-Flex».

Engines running on ethanol or a mixture of traditional fuel and ethanol are aware of the difficulties in starting at low temperatures.

Conventional fuels particularly mean the fuel used classically in positive-ignition engines, commonly called gasoline or super-fuel (premium gasoline).

In particular, when the engine is cold, the ignition of ethanol being more difficult 15 than that of gasoline will make the start more difficult. The concept of the cold engine is understood in view of the temperature of the liquid contained in the engine's cooling circuit.

_ It is known that, according to the proportion of ethanol contained in the fuel, and in particular when it is high, starts at low temperatures can become problematic, that is, result in a longer start, as it is impossible to maintain the engine in particularly low temperature conditions.

A device is also known to allow cold starts of engines running on an ethanol mixture. Brazilian Patent Application 25, BRPI8801648 shows a particular configuration of said device.

This device comprises an additional reservoir filled with a second fuel, with a low ethanol content. This fuel could be the classic super-fuel (premium gasoline), referred to as EO, but it could also be, for example, a premium gasoline (superior conventional) comprising 22% by volume of ethanol, referred to as E22, widely sold in the Brazilian market for example, or E26 with 26% by volume of ethanol.

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When starting cold, and in the presence of an important concentration of ethanol in the fuel, the starting device assists the introduction of fuel with a low concentration of ethanol in the engine intake.

However, if the introduction of fuel low in ethanol will allow the vehicle to start, taking a relatively long starting time. In fact, the fuel being introduced into the intake duct, was found by the inventor that it takes time for the fuel to reach the combustion chamber of the engine. This may result in a delay of one to two seconds for the engine to start (start).

In the present invention, the solution to these problems consists of making a pre-introduction of the fuel with low ethanol content, for the intake of the engine, even before the request to start the engine is carried out.

More precisely, the invention therefore concerns, in a method of starting a combustion engine powered by a first fuel containing 15 ethanol, said engine being equipped with a cold starting auxiliary system comprising a reservoir of a second fuel with low ethanol content, in which the engine coolant temperature is determined, determining the ethanol proportion in the first fuel, and characterized by assessing whether the engine coolant temperature 20 is below a critical temperature predetermined and if the proportion of ethanol in the fuel is higher than a predetermined value, by making the pre-introduction of the second fuel for the intake of the engine, in response to the observation of a previous event of the request to start the engine. Thus, the fuel introduced for admission by the auxiliary starting system has 25 physically the time necessary to reach the entrance of the engine cylinders when they receive the start order. The time resulting from the request to start the engine, that is, the start of its rotation, for example for a start and the arrival of fuel with a low ethanol content, will thus be greatly reduced, since the start time is considerably reduced. between the starting order and the first combustion in the engine. The invention is therefore more effective than the level of ethanol in the reservoir of the auxiliary starting system being low, this data being therefore conditioned to the availability of fuel with low ethanol rate in a

3/7 market considered. In Brazil, for example, for positive-ignition engines, the fuel sold with the lowest level of ethanol still has 22% by volume of ethanol. In general, therefore, "low ethanol content" means an ethanol proportion of less than 40% by volume, and preferably less than 30% by volume, and more preferably less than or equal to 22% by volume.

Preferably, the critical temperature is between 15 ° C and 20 ° C, and preferably equal to 18 ^o - C. The inventor has in fact found that a temperature below 18 ° C resulted in difficulties in starting the engine, in 10 particularly if it is fed with a fuel containing more than 22% by volume of ethanol.

Preferably, the predetermined value for the proportion of ethanol in the first fuel is between 22% and 100% by volume. Indeed, a fuel containing up to 22% by volume of ethanol is generally not a problem for starting the engine. In addition, in certain markets such as

In Brazil, E22 fuel, that is, containing 22% by volume of ethanol, is distributed in substitution of traditional fuel without ethanol. In the models - Combustível-Flex, it is possible to fill successively with fuels with very varied ethanol levels, for example E0 (without ethanol) 20 or E22 or E26, and E85 (containing 85% by volume of ethanol), or even

E100 (100% vol. Ethanol). In fact, the main reservoir (tank) (first reservoir) of the engine may contain a fuel with 0 to 100% by volume of ethanol. The specific known devices make it possible to estimate the ethanol content of the fuel with an accuracy of 25 in the order of 5% by volume.

Preferably the amount of the second pre-introduced fuel will be dependent on the engine coolant temperature. In fact, the lower the engine temperature (estimated for the temperature of your coolant), the more the starting will be problematic.

Preferably, the amount of the second pre-introduced fuel will be dependent on the proportion of ethanol in the first fuel. In fact, the higher the level of ethanol in the fuel in the main reservoir, the more problematic the engine will start.

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-15.

Preferably, the amount of the second pre-introduced fuel is modulated and the duration of the pre-introduction is modulated. As part of a pre-introduction system, a substantially constant flow injector is a simple device to be implemented. By modulating the injection time, the amount of low-ethanol fuel introduced into the engine intake is simply modulated.

Preferably, the duration of the pre-introduction is modulated according to a predetermined mapping.

Preferably, a minimum time interval is provided between the two pre-introductions. Thus, if the event before the engine starts is observed more than once, just before an effective start, a single pre-introduction will be carried out. In a variant configuration of the invention, the method is applied to a vehicle with doors, the event observed before the engine starts is the unlocking or opening of at least one door. This event resulting in access to the vehicle thus allows to suppose that several successive starts will be produced, making it necessary to pre-introduce the fuel according to the invention. It can also be followed, in particular the opening of the door giving access to the driver.-It is the simplest event to detect —— before the engine usually starts, especially since current vehicles are generally equipped with door opening detectors.

In another configuration of the invention where it is applied to an engine fitted to a vehicle, the observed event prior to the engine starting will be the detection of a transponder present on a freehand starting card or on an engine contact switch. If the vehicle is equipped with a freehand starting system, the detection of the transponder of a freehand starting card is the event preceding the departure authorization. This detection is perfectly suited to the pre-entry command. In the case where the vehicle's engine is activated with the aid of a contact key, a transponder will generally be present on the key, as well as on the safety device. Preventing the engine from starting with a copy of the key. The detection of this transponder may serve as an event observed before the engine starts, even if the time elapsed between the detection of the transponder and the order of the engine starting (the activation of the switch) may be short.

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In a configuration of the present invention where it is applied to an engine fitted to a vehicle, an event observed prior to starting the engine is the detection of pressing the brake pedal or the clutch pedal of the vehicle. Depending on the vehicle equipped, the observation of these events may be particularly relevant. In effect, in a vehicle equipped with an automatic gearbox, pressing the brake pedal will be necessary to start the engine. Thus, in such a vehicle, pressing the brake pedal while the engine is stationary reflects very likely that a start will come. Thus, according to certain laws, pressing the clutch pedal on a vehicle equipped with a manual gearbox may require authorization to start the engine.

In another configuration of the invention where it is applied to an engine fitted to the vehicle, the event observed prior to starting the engine is the buckling of the driver's seat belt or the detection of the presence of a driver. - - —-— - .....

This is another simple event to be detected with the sensors that often pre-exist in the use of the method according to the invention.

The invention will be described in more detail below, “with reference to the attached drawings, presented by way of example and not limitation, in which:

- Figure 1 schematically shows the general architecture of an auxiliary system for starting a flex fuel type engine;

- Figure 2 shows for a given application the pre-introduction time retained as a function of the engine temperature and the level of ethanol in the fuel.

In Figure 1, a flex fuel type 1 engine, that is, it can be powered by a fuel containing a certain proportion of ethanol and fed into a first fuel by a first reservoir 2. The level of ethanol present in the fuel can be determined with the aid of a probe 3, in connection with the motor control 4.

A device makes it possible to measure the temperature of the liquid circulating in the cooling circuit not shown in motor 1. This information can be transmitted to the motor control.

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An auxiliary starting device comprises a reservoir of a second fuel 5, and a metering device 6 controlled by the engine control 4, and allowing the introduction of the second fuel for the intake of the engine. Traditionally, this introduction of the second fuel will be carried out 5 through the butterfly valve 7, when the engine is equipped to do so. The second reservoir is intended to be supplied with fuel for the ignition-controlled engine ("super-fuel") (or premium gasoline) containing the lowest possible level of ethanol. According to the market, you can have the fuel called EO, containing 0% ethanol, or for example the

E22, containing 22% by volume of ethanol, or even E26, containing 26% by volume of ethanol.

When an event preceding the start of the engine, it can be according to the application and in a non-exhaustive way the opening of a door of the equipped vehicle or the opening of the door allowing access to the driver's station; The . 15 - detection of a card on the free hand card transponder, detection of a - transponder contained in the contact key, buckling of the driver's safety belt, or pressing of the cold pedal or - - clutch, being detected by the control engine 4 that integrates the information ^- temperature of the liquid contained in the cooling circuit of engine 1 and the ethanol level of the first fuel contained in the first reservoir 4.

If the temperature of the liquid contained in the cooling circuit of engine 1, which reveals the temperature of engine 1, is lower than a first predetermined value, and if the ethanol level of the first fuel is higher than a second predetermined value, the control The engine will then command a pre25 introduction of the second fuel contained in the second reservoir 5, for the intake of the engine through the auxiliary starting system. The measuring device 6 will “ensure that the desired quantity of the second fuel is introduced into the intake. In practice, it is the duration of the pre-introduction that is modulated in order to modulate the quantity of the second fuel.

For the application shown here, corresponding to a 2.0L four-cylinder engine with 16 cylinders and 16 valves, the inventor has empirically determined the ideal pre-introduction time for the application considered, depending on the temperature of the cooling liquid in the circuit. cooling

7/7 engine, and the ethanol level in the first fuel. In the case of the figure considered, the second fuel will be E22 with 22% by volume of ethanol. Temperatures (in columns) are expressed in degrees Celsius (° C). The ethanol level is reported as an air / fuel ratio or A / F (in lines), with the stoichiometry being different for the super-fuel (premium gasoline) EO (reported as A / F = 14.7) and for ethanol at 100% E100 (reported as A / F = 9.0), the A / F ratio for stoichiometry reflects the level of ethanol present in the fuel.

It can be seen in Figure 2 that the pre-introduction time, and therefore the amount of the second pre-introduced fuel, will be particularly more important that the engine temperature is low and that the ethane level in the first fuel will be important. However, at the price of a pre-introduction for 1.2 seconds, a quick start at -10 ° C with a first · fuel containing 100% ethanol is guaranteed.

-—On the contrary, the pre-introduction will always be useless, for the considered application, even if the temperature of the engine coolant is equal to or exceeds 18 ° C or the A / F ratio for the stoichiometry of the first fuel is equal or exceed '12 ° Cr -

Thus, with the help of a pre-introduction adapted to the starting situation, it will be possible to start almost instantly, that is, from the starting order of the engine, an engine running on a fuel that can contain up to 100% ethanol for low temperatures, notably on the order of -10 ° C.

Claims (12)

1. METHOD OF STARTING A COMBUSTION ENGINE FUELED WITH A FUEL CONTAINING ETHANOL ”, said engine being equipped with an auxiliary cold starting system comprising a reservoir (5) of a second fuel with a low ethanol content, in which determines the engine coolant temperature, determining the proportion of ethanol in the first fuel, characterized by detecting whether the engine coolant temperature (1) is below a predetermined critical temperature and whether the proportion of ethanol in the fuel is higher than a predetermined value, if the second fuel is pre-introduced for the engine intake (1) in response to the observation of an event prior to the engine start request. 2. "METHOD", according to claim 1. characterized by the critical temperature between 15 ^o C and 20 o C, and preferably equal to 18 ^o C. 3. "METHOD" according to claims 1 and 2, characterized in that the predetermined threshold value is comprised between 22% and 100% by volume. 4. "METHOD" according to claims 1, 2 and 3, characterized in that the amount of the second pre-introduced fuel is dependent on the coolant temperature in the engine (1). 5. "METHOD" according to claims 1, 2, 3 and 4, characterized in that the amount of the second pre-introduced fuel is dependent on the level of ethanol in the first fuel. 6. "METHOD" according to claims 4 and 5, characterized by modulating the amount of the second pre-introduced fuel and modulating the pre-introduction duration. 7. "METHOD", according to claims 4, 5 and 6, characterized in that the duration of the pre-introduction is modulated according to a predetermined mapping. 8. "METHOD" according to claims 1, 2, 3, 4, 5, 6 and 7, characterized in that there is a minimum predetermined time interval between the two pre-introductions. 9. "METHOD", according to claims 1,2,3, 4, 5, 6, 7 and 8, applied to an engine (1) equipped with a vehicle equipped with doors, characterized by the 2/2 event observed prior to starting the engine is the unlocking or opening of at least one door. 10. "METHOD", according to claims 1, 2, 3, 4, 5, 6, 7 and 8, applied to an engine (1) equipped with a vehicle, characterized by the observed event 5 prior to starting the engine is the detection of a transponder on a freehand starting card or by presenting a motor contact key. 11. "METHOD", according to claims 1,2, 3, 4, 5, 6,7 and 8, applied to an engine (1) fitted to a vehicle, characterized in that the event observed prior to the engine starting is the detection of the pedal pressure 10 vehicle brake or clutch pedal. 12. "METHOD", according to claims 1,2, 3, 4, 5, 6, 7 and 8, applied to an engine (1) fitted to a vehicle, characterized in that the event observed prior to the engine starting is the buckling the driver's seat belt, or detecting the presence of a driver.