FR3107571A1 - STARTING PROCEDURE OF A MOTOR VEHICLE COMBUSTION ENGINE - Google Patents

Abstract

A method of starting a combustion engine of a motor vehicle, the method comprising the following steps: (a) starting test by activating a starter of the combustion engine up to a given duration; and (b) if the combustion engine fails to start as a result of the previous step (a), additional start test by performing step (a); step (b) being executed a number of times n greater than or equal to 1; the number n of additional starting test (s) being variable and depending on the operating conditions of the combustion engine. Figure 2

Description

METHOD FOR STARTING A MOTOR VEHICLE COMBUSTION ENGINE

The invention relates to the field of motor vehicles, and more particularly to motor vehicles with internal combustion engines.

Currently, most combustion vehicles include an automatic engine stop and restart system, also called "Stop & Start", comprising a conventional starter and a reversible alternator or alternator-starter. The starter is intended to carry out the first starts of the engine, then the reversible alternator takes over, and makes it possible to recharge the battery of the vehicle the rest of the time.

In addition, the starting control logic usually provides, when the vehicle fails to start after several attempts, a fault setting making it impossible to start the vehicle for a certain period of time. The number of attempts before the vehicle fails is fixed, and is a compromise between the capacities of the conventional starter and the reversible alternator, and between the different possible starting conditions.

The patent document FR2839119B1 discloses a starting system for an engine equipped with two starters, a belt starter and a gear starter. When a starting fault prevents the operation of one of the two starters, the second takes over to try to light the vehicle. The activation of one or the other of the starters is carried out by a control unit, which also determines the operating conditions of the vehicle that are suitable or not for starting. But this system is heavy and cumbersome because it includes two starters, and leads to overconsumption of fuel.

The published patent document WO2008/029363A2 discloses a method for protecting a starter according to the operating conditions of the combustion engine, such as the temperature of said engine. An electronic control unit performs functional checks before authorizing use of the starter. Subsequently, the temperatures of the combustion engine cooling water, the intake air and the fuel are measured, and the control unit will determine a maximum duration for the vehicle start attempt.

The aim of the invention is to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the aim of the invention is to optimize the starting system of a combustion engine, from a performance point of view and preferably from an equipment point of view.

The subject of the invention is a method for starting a combustion engine of a motor vehicle, the method comprising the following steps: (a) attempt to start by activating a starter of the combustion engine for a given duration; and (b) in the event of a failure to start the combustion engine following step (a) above, an additional start attempt by performing step (a); step (b) being performed a number of times n greater than or equal to 1; remarkable in that the number n of additional start attempt(s) is variable and depends on the operating conditions of the combustion engine.

According to an advantageous embodiment of the invention, the number n of additional start attempt(s) is increased when the operating conditions of the combustion engine are unfavorable to starting.

According to an advantageous embodiment of the invention, the operating conditions of the combustion engine include the ambient temperature, the temperature of the combustion engine and/or the ambient humidity.

According to an advantageous embodiment of the invention, the starter in step (a) is kinematically connected to a crankshaft of the combustion engine by a belt.

According to an advantageous embodiment of the invention, the starter in step (a) is an alternator-starter capable of producing electrical energy once driven by the combustion engine.

According to an advantageous mode of the invention, the starter in step (a) is the only starter of the combustion engine.

According to an advantageous embodiment of the invention, the operating conditions of the combustion engine unfavorable to starting include conditions indicating that the belt is at least partially covered with ice.

According to an advantageous embodiment of the invention, the method comprises the following additional step: (c) in the event of failure to start the combustion engine following n times the execution of step (b), emission of an engine fault signal.

The subject of the invention is a motor vehicle comprising: a combustion engine; and a combustion engine start control unit; remarkable in that the control unit is configured to execute the method according to the invention.

According to an advantageous embodiment of the invention, the starter is an alternator-starter kinematically connected to a crankshaft of the combustion engine by a belt, and is the only starter of said combustion engine.

The measures of the invention are interesting in that they make it possible to optimize the starting system of a combustion engine, from a performance point of view and preferably from an equipment point of view. The invention also makes it possible to adapt the number of starts achievable with a heat engine, according to the climatic conditions in which it is found. Thus, if the engine is in unfavorable climatic conditions for effective ignition, the number of possible starting attempts, before the engine faults, is increased. The measures of the invention are particularly suited to an alternator-starter connected kinematically to the engine by a belt, which is more subject to the vagaries of the weather. The use of an alternator-starter also makes it possible to reduce vehicle manufacturing costs, as well as to reduce engine assembly time by avoiding the installation of an additional conventional starter. The absence of this additional starter also makes it possible to reduce the total weight of the engine, therefore to reduce the fuel consumption of the vehicle. This absence also makes it possible to reduce the noise produced during starting, since an alternator-starter, due to the connection to the engine by belt, is silent, therefore it allows a more pleasant driving for the driver.

Other features and advantages of the present invention will be better understood from the description and the drawings.

is a diagram representing a motor vehicle according to the invention;

is a flowchart representing the different steps of the method according to the invention.

detailed description

The examples described below are given for information only, but other applications or embodiments of the invention not described may be considered.

Figure 1 is a diagram representing a motor vehicle according to the invention.

The vehicle 1 comprises a combustion engine 3 and a start-up control unit 5 of the combustion engine 3. The combustion engine 3 is started using a starter, which is, preferably, an alternator-starter 7. This alternator-starter 7 is kinematically connected to a crankshaft 9 of the combustion engine 3 by a belt 11, the alternator-starter 7 preferably being the only starter of the engine 3.

A battery 13 provides the electrical supply to the alternator-starter 7, which then allows the rotation of the belt 11 then the rotation of the crankshaft 9. The crankshaft 9 causes the starting of the engine 3. Subsequently, the alternator- starter 7, thanks to its alternator function, will be able to recharge the battery 13 of the vehicle 1 and allow the electrical supply of said vehicle 1. The start control unit 5 of the engine 3 controls the different stages of the start of the vehicle 1 , and is in particular configured to execute a method according to the invention, described in FIG. 2. Sensors (15A, 15B) are also represented in this figure, their respective functions will be described in FIG. 2.

Figure 2 shows the different steps of the start-up method according to the invention. Figure 2 is described with reference to Figure 1.

It is more precisely a process for starting the combustion engine 3 of the motor vehicle 1. This process comprises several steps. In this figure, i corresponds to the number of engine start attempts 3.

A first step (a) consists in performing a start test of engine 3 of vehicle 1 by activating the starter of said engine 3. This is a first test, so i=1. This test has a given duration predefined by the start-up control unit 5. This predefined duration is not necessarily fixed; it can vary according to various operating parameters of the combustion engine 3, such as in particular its temperature. This starter is preferably an alternator-starter 7, which will produce electrical energy once driven by the combustion engine 3. This alternator-starter 7 is preferably the only starter of the engine 3, which allows a reduction in mass of the engine 3. The alternator-starter 7 is kinematically connected to the crankshaft 9 by the belt 11.

In the event of failure to start the engine 3 following step (a), a second step (b) is then triggered. This step (b) results in an additional start attempt i=i+1 by executing step (a) again. This step (b) can be performed a number of times n , this number n being greater than or equal to 1. This number of additional start-up attempts n depends on the operating conditions of the combustion engine 3. It is therefore variable. In particular, the number n of additional test(s) is increased when the operating conditions of engine 3 are unfavorable to the starting of said engine 3.

Advantageously, the operating conditions of the combustion engine 3 include the ambient temperature, the temperature of the engine 3 and/or the ambient humidity. These different conditions can be measured using sensors (15A, 15B), which can in particular be temperature sensors 15A or hygrometry sensors 15B. The values measured using the sensors (15A, 15B) are then compared with values predefined by the start-up control unit 5, and, according to the variations detected with respect to a standard, the control unit 5 will estimate a variation in the number of possible start-up trials n . Thus, more tests can be allowed under particularly unfavorable operating conditions. One of the unfavorable conditions for starting the engine 3 comprises a condition indicating that the belt 11 is icy, that is to say at least partially covered with ice.

A last step (c) of the method consists in, in the event of failure to start the engine 3 following n times the execution of step (b) (therefore when i=n), the emission of a signal motor 3 fault. Motor 3 can no longer be started for a predefined period. This step can prove to be important, in particular in the event of an engine failure 3 potentially dangerous for the user.

Claims (10)

Method for starting a combustion engine (3) of a motor vehicle (1), the method comprising the following steps:
(a) attempt to start by activating a starter of the combustion engine (3) for a given duration; And
(b) in case of failure to start the combustion engine (3) following the previous step (a), additional start attempt by performing step (a);
step (b) being performed a number of times n greater than or equal to 1;
characterized in that the number n of additional start attempt(s) is variable and depends on the operating conditions of the combustion engine (3). Starting method according to Claim 1, characterized in that the number n of additional starting attempts is increased when the operating conditions of the combustion engine (3) are unfavorable to starting. Starting method according to one of Claims 1 and 2, characterized in that the operating conditions of the combustion engine (3) comprise the ambient temperature, the temperature of the combustion engine (3) and/or the ambient humidity. Starting method according to one of Claims 1 to 3, characterized in that the starter in step (a) is kinematically connected to a crankshaft (9) of the combustion engine (3) by a belt (11). Starting method according to claim 4, characterized in that the starter in step (a) is an alternator-starter (7) capable of producing electrical energy once driven by the combustion engine (3). Starting method according to one of Claims 4 and 5, characterized in that the starter in step (a) is the only starter of the combustion engine (3). Starting method according to Claim 2 and according to one of Claims 4 to 6, characterized in that the operating conditions of the combustion engine (3) unfavorable to starting include conditions indicating that the belt (11) is at least partially covered with ice. Starting method according to one of Claims 1 to 7, characterized in that the method comprises the following additional step:
(c) in the event of failure to start the combustion engine (3) following n times the execution of step (b), transmission of an engine fault signal (3). Motor vehicle (1) comprising:
- a combustion engine (3); And
- a start control unit (5) of the combustion engine (3);
characterized in that the control unit (5) is configured to execute the method according to one of claims 1 to 8. Motor vehicle (1) according to Claim 9, characterized in that the starter is a starter-alternator (7) kinematically connected to a crankshaft (9) of the combustion engine (3) by a belt (11), and is the single starter of said combustion engine (3).