EP0793015B1 - Method and device for stopping a starter motor of a vehicle after start of his combustion engine - Google Patents

Description

The present invention relates to a method and to a device for switching off a vehicle starter automobile after starting the heat engine thereof.

Usually stopping the training of the engine by starter is controlled by the user of the vehicle who releases the ignition key when the engine makes a characteristic noise.

However, the tendency to make engines more and more quiet thermal makes it becomes difficult for the user to detect the end of the start-up. This results in more severe solicitation of the starter.

We already know many devices for cut a motor vehicle starter when the engine has started and is sufficiently autonomous to reach its idle speed by itself.

In particular, it has already been proposed in the request. FR 2 626 417 to order the cutting of the starter when the frequency of the ripples of the voltage across it or the current current flowing through it is above a given threshold. This solution exploits the characteristic according to which the frequency of ripples - which correspond to successive compressions of the heat engine - is increasing with time.

However, this solution does not stop the starter immediately after starting the engine at combustion.

Obtaining a frequency measurement supposes in effect a signal analysis on a time window long enough. Therefore, when the frequency threshold is reached, the starter cut-off order is delayed until the end of the first time window allowing the measurement of a frequency higher than this threshold frequency.

In addition, the effective starting speed of the engine is a function of many parameters and in particular of the state of wear of its components, its injection and ignition system or temperature ambient. In order not to risk, in some cases, cut the starter prematurely, the speed threshold at from which the starter is cut is generally very higher than the actual engine start speed. Therefore, in most cases, the starter works well beyond the time that would be required.

We also know by FR 2 393 165, a starter control device which cuts the starter when the ripples of its voltage or its intensity disappear. For this purpose, the voltage signal or intensity is sent on two channels, one of which is delayed. As long as there are ripples, both tracks are at different levels. When the ripples disappear, the two paths are the same level and the device cuts the starter.

However, with such a device, the control of the cut occurs, relative to the engine start thermal, with a delay time corresponding to the delay from the second line.

An object of the invention is to propose a method and a device for cutting a starter from motor vehicle as soon as the heat engine thereof has reached its autonomy threshold, the start-up time being systematically reduced to just what is necessary.

This improves the comfort of use and possibly simplify the starter itself by eliminating its freewheeling function.

According to the invention, this object is achieved in that for each new ripple, a period of scrutiny of a duration which decreases with the increase of the frequency of the ripples and in that we cut the starter when no new ripple is detected in the last polling period.

The invention also proposes, in order to implements this process, a device for controlling the shutdown of a motor vehicle starter comprising means for detecting ripples of a signal corresponding to the supply voltage of this starter or the intensity flowing through it, as well as means for controlling the cut-off of this starter when these ripples disappear, characterized in that it includes means for generating, for each new ripple, a scanning period of duration which decreases with increasing frequency of ripples and in that the means of cutting the starter cut off this one when no new ripple is not detected in the last period of scrutiny.

• les moyens de détection d'ondulations comportent des moyens pour générer à chaque nouvelle ondulation une impulsion de remise à zéro de la période de scrutation ;
• le dispositif comporte des moyens de traitement pour transformer les ondulations du signal en un signal rectangulaire d'amplitude constante et de même période que les ondulations et en ce que la période de scrutation est fonction de la durée d'un créneau élémentaire de ce signal rectangulaire ;
• le dispositif comporte un temporisateur à durée commandée en tension, dont l'entrée de commande est commandée par la tension d'un condensateur alimenté par le signal rectangulaire et en ce qu'il comporte des moyens pour décharger ce condensateur à chaque impulsion de remise à zéro ;
• le dispositif comporte un compteur qui est réinitialisé à chaque nouvelle impulsion de remise à zéro, la durée de la période de scrutation étant fonction de la valeur de ce compteur à chaque nouvelle impulsion ;
• le dispositif comporte un décompteur réinitialisé à une valeur fonction de la valeur du compteur à la réception de chaque nouvelle impulsion de remise à zéro ;
• le compteur et le décompteur sont commandés par un même signal d'horloge, la valeur de réinitialisation du décompteur étant choisie supérieure à la valeur du compteur ;
• à chaque impulsion de remise à zéro, le décompteur est réinitialisé avant le compteur.

This device is advantageously supplemented by the following different characteristics taken alone or in all their technically possible combinations:

• the ripple detection means comprise means for generating, with each new ripple, a reset pulse for the scanning period;
• the device comprises processing means for transforming the ripples of the signal into a rectangular signal of constant amplitude and of the same period as the ripples and in that the scanning period is a function of the duration of an elementary slot of this rectangular signal ;
• the device comprises a voltage-controlled duration timer, the control input of which is controlled by the voltage of a capacitor supplied by the rectangular signal and in that it comprises means for discharging this capacitor on each reset pulse zero;
• the device comprises a counter which is reset on each new reset pulse, the duration of the scanning period being a function of the value of this counter on each new pulse;
• the device comprises a down counter reset to a value depending on the value of the counter on receipt of each new reset pulse;
• the counter and the down counter are controlled by the same clock signal, the reset value of the down counter being chosen to be greater than the value of the counter;
• at each reset pulse, the down counter is reset before the counter.

• la figure 1 est un schéma d'un dispositif de commande de coupure d'un démarreur conforme à un mode de réalisation possible pour l'invention ;
• la figure 2 est un schéma synoptique sur lequel on a illustré un mode de réalisation possible pour les moyens de commande du dispositif de la figure 1 ;
• les figures 3a à 3e représentent différents signaux obtenus en sortie des étages de traitement des moyens de la figure 2 ;
• la figure 4 est un schéma illustrant un mode de réalisation possible pour le temporisateur à durée de temporisation variable des moyens de commande de la figure 2 ;
• les figure 5a à 5c illustrent différents signaux de commande du temporisateur de la figure 4 ;
• la figure 6 est une représentation synoptique semblable à celle de la figure 2 illustrant un autre mode de réalisation possible pour les moyens de commande d'un dispositif conforme à l'invention ;
• les figures 7a à 7e sont des figures semblables aux figures 3a à 3e et représentent différents signaux obtenus en sortie des étages de traitement des moyens de la figure 6.

Other characteristics and advantages of the invention will emerge from the description which follows. This description is purely illustrative and not limiting. It must be read in conjunction with the appended drawings in which:

• Figure 1 is a diagram of a cut-off control device of a starter according to a possible embodiment for the invention;
• Figure 2 is a block diagram on which there is illustrated a possible embodiment for the control means of the device of Figure 1;
• Figures 3a to 3e show different signals obtained at the output of the processing stages of the means of Figure 2;
• FIG. 4 is a diagram illustrating a possible embodiment for the timer with variable delay duration of the control means of FIG. 2;
• Figures 5a to 5c illustrate different control signals of the timer of Figure 4;
• Figure 6 is a block diagram similar to that of Figure 2 illustrating another possible embodiment for the control means of a device according to the invention;
• FIGS. 7a to 7e are figures similar to FIGS. 3a to 3e and represent different signals obtained at the output of the processing stages of the means of FIG. 6.

FIG. 1 illustrates a device for controlling the supply of a starter motor D which comprises an electric motor M mounted between a supply terminal B ⁺ at the voltage of the vehicle battery and ground.

This device comprises a contactor 1 mounted between the terminal B ⁺ of supply to the battery voltage and the starter D.

This contactor 1 is a relay actuated by a winding 2. One of the ends of this winding 2 is connected to the supply terminal B ⁺ . Its other end is connected on the one hand to the source of a MOSFET transistor 3 and on the other hand to a coil 5 connected to ground.

The drain of transistor 3 is connected to the supply terminal B ⁺ . Its gate is connected to the output of a unit 4, from which it receives a control voltage.

Of course, transistor 3 could be replaced by any other type of switch.

In the example illustrated in these figures, the unit 4 generates said control voltage as a function on the one hand of the undulations of the voltage of the supply terminal B ⁺ , and on the other hand of the position of the contactor actuated by the ignition key (switch 6).

The processing carried out by the control unit 4 will now be described in detail with reference to Figures 2 and 3a to 3e.

During the starting phase of the heat engine, the input voltage of unit 4 (voltage of terminal B ⁺ ) is of the type illustrated in FIG. 3a. This voltage has, as long as the engine has not started, ripples whose frequency increases with the speed of said engine. These ripples disappear when the engine has started.

As illustrated in FIG. 2, this signal is filtered by a low-pass filter 7. Its continuous component is then deleted in stage 8. The signal then obtained is of the type of that of FIG. 3b, which corresponds to the filtered alternating component of the signal of Figure 3a.

In a subsequent stage 9 (FIG. 2), this signal is transformed into a niche signal of the type of Figure 3c. To this end, this stage 9 transforms the negative pulses of the signal at the output of stage 8 in positive pulses of constant amplitude and similarly duration than these negative impulses.

The niche signal thus obtained at the output of stage 9 is sent on the one hand to a generator of pulses 10 and on the other hand on a timer 11.

The generator 10 generates on the rising edges of the niche signal of short duration pulses (figure 3d), which reset the time delay generated by the timer 11 (figure 3d).

Each reset, the duration of the new Tsi delay generated is modified according to the duration Tci of the rectangular elementary signal at the output of stage 9, so as to be decreasing from one pulse to the other. This duration Tsi is chosen to be greater than two times the duration Tci of the last elementary signal rectangular, so that, as long as the input signal of unit 4 has ripples, a new ripple occurs before the end of each timer, the timer is then reset to zero by the impulse that corresponds to this new ripple.

Unit 4 includes means 12 for inhibiting the blocking of transistor 3, as long as the time delay is thus maintained by the ripples of the input signal. The control voltage of the gate of transistor 3 is at a level (level 1 in Figure 3e), where it controls the closing of said transistor 3, so that the winding 2 is short-circuited and that contactor 1 is closed.

The blocking circuit that constitutes the means 12 is also inhibited by reset pulses zero (figure 3d). The starter is therefore not stopped inadvertently by resetting the timer 11.

When the ripples disappear, that is to say when the engine starts, the pulses reset (Figure 3d) also disappear and the timer ends.

The blocking of transistor 3 is no longer inhibited (signal of figure 3e at its level 0). The winding 2 is no longer short-circuited and contactor 1 is open. The starter is then cut off.

With such a device, the time between starting the engine and switching off the starter is particularly short, since it is less than the last time delay Tsi generated.

An example of a possible circuit for timer 11 is illustrated in FIG. 4.

It has an integrated timing circuit 13, of a standard type, having an entry 13a of voltage-controlled duration control.

A capacitor C is mounted between this input 13a and mass.

This capacitor C is charged by a signal elementary in niche through a diode D and a resistance R, the charging voltage Uc across the capacitor C being transmitted, possibly by through an amplifier, at input 13a.

Diode D prevents capacitor C from discharge when said elementary signal disappears.

The reset signal drives a transistor T mounted between capacitor C and ground. He provokes rapid discharge of capacitor C via of said transistor T.

The circuit 13 is therefore controlled by a voltage which corresponds to the average voltage of Uc and which is a function of the duration Tc of the last rectangular elementary signal received.

This is what has been illustrated in FIG. 5c, on which is shown the voltage Uc, the signal in niche and the reset pulses having been shown in Figures 5a and 5b. In Figure 5c, the average value of the voltage Uc is shown in lines mixed and is also indicated by the double arrows.

In Figure 4, there is also shown the input 13b time base of the timing circuit 13, as well as its control output 13c, which is maintained by a capacitor C1 at the control voltage of the transistor 3 is closed, as long as the time delay is not not finished, and which discharges the capacitor C1 at the end time delay.

Another possible embodiment has been illustrated in Figures 6 and 7a to 7e.

We repeated for the elements of Figure 2 which are found in Figure 6 the same numbering of reference increased by 100.

The input signal is the voltage taken from the electric motor supply terminal B ⁺ (figure 7a).

This signal is sent to a low-pass filter 107 which rids this input signal of its parasites.

The next floor 108 removes the component of the filtered signal. The alternative signal obtained is of the type illustrated in FIG. 7b.

The signal at the output of this stage 108 is transmitted to a low level detector 120.

This detector 120 generates a succession short pulses, calibrated in duration and amplitude (Figure 7c). These pulses are sent to a counter 121 which also receives a signal from a clock 122 increment.

Each pulse characterizes an end of phase of compression of the motor driven by the starter D.

Counter 121 is reset to zero by each impulse. The value it reaches before each delivery to zero by a pulse characterizes the duration between two successive engine compressions.

The pulses generated by the detector 120 of low level are also transmitted, with the signal incrementing the clock 122, to a down counter 124 which is reset with each new pulse.

The value at which the down-counter 124 is reset is a function of the time between the two last pulses measured by the counter 121.

In the example described here, the content Tc of counter 121 is transmitted to a multiplier operator 123 which multiplies it by a value k greater than 1. The value at output of multiplier 123 is transmitted to down counter 124.

The scrutiny period thus defined by the countdown made by the downcounter 124 is therefore greater during the compression cycle of the engine.

So, as long as the engine has not started, the down-counter 124 is reset before the end of its periods of scrutiny by impulses successively generated by the ripples of the signal input (Figure 7d).

The blocking of transistor 3 is then inhibited by the means 112 (signal of FIG. 7e at its level 1).

When the engine has started, the starter no longer transmits torque, so that ripples and impulses disappear. The absence pulses during a scan period means so that the engine has started.

Therefore, when the value 0 is reached by the downcounter 124, the means 112 are controlled from so as no longer to inhibit the blocking of the transistor command 3 (signal of figure 7e at its level 0). The contactor 1 goes to open state.

Note that working with scan periods greater than cycle periods engine compression prevents wrong and premature stopping following rotational speed irregularities.

For the proper functioning of the system, the down-counter 124 is reset before resetting the counter 121. For this purpose, a delay circuit can be provided on the reset input of counter 121. Alternatively, we can also use the rising edge of the pulses to reset the downcounter 124 and their front descending to reset counter 121.

Starting the system requires either a inhibition of the blocking circuit of transistor 3 during at least one compression, i.e. an initial loading of a value in the down-counter 124.

Other variant embodiments may also be considered.

In the second variant described, the multiplier can be removed if we do the counting down at a frequency lower than that of counting. You can for this purpose insert a circuit divider, for example with flip-flop, between the clock 122 and the down-counter 124.

Generally, instead of the voltage signal available at the starter or battery terminals, the signal processed by unit 4 can be a signal corresponding to the intensity of the current passing through the starter D.

This intensity signal can be obtained by measuring the voltage drop on conductive elements having an essentially ohmic characteristic, which are in series with the starter, such as power contacts of contactor 11, the connecting cable between the contactor 11 and the starter D, the ground return cable of the starter D, the power cable between the battery B ⁺ and the starter D.

Alternatively, this current intensity can be obtained by measuring the voltage variations induced in a measuring coil crossed by one of the elements previously cited drivers.

In another variant, the signal pulses illustrated in figures 3d or 7c can be generated by a zero crossing detector of the component alternative of the filtered signal (instead of the low level or high level).

Also, the motor drive by the starter can be characterized by the derivative of the supply voltage or current. During the passages of compression, when the starter drives the engine, the derivative of the voltage is negative and the derivative of the current is positive. A monostable rocking device allows to trigger a signal at the beginning or at the end of the starter training period.

As will be understood, a time delay variable of the type just described allows to adapt to the engine speed by cutting at most the starter early, without risking a stop command untimely.

At the end of starter training, when the heat engine starts to run independently, the speed is of the order of 300 to 400 revolutions / minute, or a duration between two successive pulses from 0.07 to 0.1 seconds.

However at the start of start-up, and in particular cold start, the speed can be 70 rpm only, that is to say a duration between two pulses of 0.43 seconds.

If we used a fixed time delay set to 0.1 seconds, the starter stop order would be given before the first engine revolution because it would not appear reset signal before switching over timer.

A fixed time delay set to 0.43 seconds would drive the engine cold, but the order starter stop would be very late and could even intervene, especially when the engine is warm, with high motor speeds of the order of 1000 to 1500 revolutions / minute, i.e. a pinion speed for the starter 12,000 to 20,000 rpm.

At these speeds, the starter is particularly noisy and undergoes accelerated wear. In addition, the presence of a freewheel is imperative.

Note also that with the time delay proposed by the invention, the starter breaking is independent of the characteristics of the engine, including the number of cylinders, characteristics injection and ignition, wear or adjustment condition engine, battery characteristics ...

In addition, the proposed solution presents the advantage of being entirely autonomous and of not requiring no additional wiring during installation on the vehicle.

The assembly constituted by a control device of the type proposed by the invention and its alternator is in interchangeable effect with a conventional starter.

Note also that the current at the key switch 6 is very low: a few milliamps instead of the usual values of 10 to 40 amps. Therefore, the starter proposed by the invention can be treated as a low control current, which allows us to consider many changes to the start command, for example: control by code entry, by pedal acceleration, etc.

Claims (9)

1. Method for controlling the cutting off of a motor vehicle starter (D) according to which there are detected the ripples of a signal corresponding to the supply voltage of this starter (D) or to the current passing through it, and the starter (D) is cut off when these ripples disappear, characterised in that, for each new ripple, there is generated a scanning period (Tc) with a duration which decreases with the increase in the frequency of the ripples and in that the starter (D) is cut off when no new ripple is detected in the last scanning period (Tc).
2. Device for controlling the cutting off of a motor vehicle starter (D) having means for detecting the ripples of a signal corresponding to the supply voltage of this starter (D) or to the current passing through it, as well as means for controlling the cutting off of this starter (D) when these ripples disappear, characterised in that it has means for generating, for each new ripple, a scanning period (Tc) with a duration which decreases with the increase in the frequency of the ripples and in that the means of cutting off the starter (D) cut off the latter when no new ripple is detected in the last scanning period (Tc).
3. Device according to Claim 2, characterised in that the ripple detection means have means for generating, at each new ripple, a pulse for resetting the scanning period (Tc).
4. Device according to Claim 3, characterised in that it has processing means (9) for converting the ripples of the signal into a rectangular signal of constant amplitude and with the same period as the ripples and in that the scanning period (Tc) is a function of the duration of an elementary half-wave of this rectangular signal.
5. Device according to Claim 4, characterised in that it has a timer (13) with a voltage-controlled duration, whose control input is controlled by the voltage of a capacitor (C) supplied by the rectangular signal and in that it has means for discharging this capacitor (C) at each reset pulse.
6. Device according to Claim 5, characterised in that it has a counter (121) which is reinitialised at each new reset pulse, the duration of the scanning period (Tc) being a function of the value of this counter (121) at each new pulse.
7. Device according to Claim 6, characterised in that it has a downcounter (124) reinitialised to a value which is a function of the value of the counter (121) on reception of each new reset pulse.
8. Device according to Claims 6 and 7, characterised in that the counter (121) and downcounter (124) are controlled by the same clock signal (122), the reinitialisation value for the downcounter (124) being chosen so as to be greater than the value of the counter (121).
9. Device according to Claims 6 and 7, characterised in that, at each reset pulse, the downcounter (124) is reinitialised before the counter (121).

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