EP1058785B1 - Device for controlling a motor vehicle starter - Google Patents

Abstract

The invention concerns a device for controlling the power supply of an electric motor (M) of a vehicle, particularly a motor vehicle, starter (D), comprising a power switch (K) mounted in series with said electric motor (M), means (2, B) for controlling said power switch (K), and an auxiliary switch (T2) which shorts out said electric motor when the power switch opens. The invention is characterised in that said auxiliary switch is a static electronic component (T2).

Description

The present invention relates to devices for control of a motor vehicle starter.

Conventionally, the power supply of the electric motor of a starter is controlled by an electromagnetic power contact (relay to winding) which is actuated according to the state of the contact switch of the vehicle, either directly or through electronic management integrated or not to the starter.

When, after starting the engine, the starter is deactivated, the return to stop the armature is not immediate. The speed of rotation of the armature is maximum at the moment of deactivation, then gradually reduced as a function of time. The duration of this slowdown depends on the maximum speed, the inertia of the armature and the losses by friction.

For conventional starters, the stopping time can be to reach several seconds during which the starter emits noise at different frequencies. Generally, these noises cause inconvenience as they are easily noticeable inside the cabin of the vehicle.

To reduce these inconveniences, we try to reduce the time slow down so that it is low enough to prevent the structure of the starter and its components do not resonate.

For this purpose, it has already been proposed to mechanically brake the armature of the electric motor of the starter by a friction washer arranged between said armature and a stator bearing.

However, such mechanical braking has the disadvantage of being to be present throughout the duration of the starter operation. The performance of this one is greatly reduced.

In addition, such braking is not reliable in time, its efficiency evolves with the wear of the rubbing parts.

To overcome these disadvantages, it has also been proposed starter structures in which a mechanical auxiliary contact performs the electrical grounding of the motor power supply terminal of the starter as soon as the starter's power contact returns to its open position. Such a device is known from JP-A-61 108 870.

An object of the invention is to propose a device which is of a greater simplicity and allows for engine braking electric motor vehicle starter which is reliable in the time and does not penalize the performance of said starter.

The applicant has recently proposed in its application for patent FR 98-11.550 a device for controlling the power supply of the electric motor of a starter in which the power contact is not not a moving contact, but is a static relay constituted by a controllable electronic component, such as a power transistor.

Another object of the invention is to propose a solution for the braking of the electric motor of a starter which can be used in the case where said electric motor is controlled by such a static relay.

For this purpose, the invention proposes a device for the control of the power supply of the electric motor of a vehicle starter, in particular automobile, comprising a power switch connected in series with said electric motor, means for controlling said switch of power, as well as an auxiliary switch which bypasses said motor when the power switch opens, characterized in that said auxiliary switch is a static electronic component.

This solution makes it possible to control the slowdown of the armature with a structure of great simplicity.

It is also compatible with the use of a component static power electronics to realize the switch of power of the starter.

• un composant électronique statique est un transistor ;
• le commutateur auxiliaire est commandé par un microcontrôleur qui gère la commande de l'alimentation du moteur électrique ;
• le composant électronique statique qui constitue le commutateur est monté en série avec une résistance ;
• le composant électronique statique qui constitue le commutateur auxiliaire est commandé par un signal à impulsions à largeur modulée ;
• le composant électronique statique qui constitue le commutateur est commandé en boucle ouverte ;
• le composant électronique statique qui constitue le commutateur est commandé en fonction de l'intensité du courant qui le traverse ;
• le dispositif comporte des moyens de type shunt qui sont reliés à une entrée analogique/numérique du microcontrôleur et qui transmettent à ladite entrée une tension proportionnelle à l'intensité du courant qui traverse le composant électronique statique qui constitue le commutateur ;
• le dispositif comporte des moyens pour fermer le commutateur auxiliaire lorsque l'interrupteur de contact du démarreur et le contact de puissance (K) sont ouverts et pour l'ouvrir dans les autres cas.

The device proposed by the invention is also advantageously complemented by the following different characteristics taken alone or in all their possible combinations:

• a static electronic component is a transistor;
• the auxiliary switch is controlled by a microcontroller which manages the control of the power supply of the electric motor;
• the static electronic component which constitutes the switch is connected in series with a resistor;
• the static electronic component which constitutes the auxiliary switch is controlled by a pulse width pulse signal;
• the static electronic component that constitutes the switch is controlled in an open loop;
• the static electronic component that constitutes the switch is controlled according to the intensity of the current flowing through it;
• the device comprises shunt means which are connected to an analog / digital input of the microcontroller and which transmit to said input a voltage proportional to the intensity of the current flowing through the static electronic component which constitutes the switch;
• the device comprises means for closing the auxiliary switch when the ignition switch of the starter and the power contact (K) are open and to open it in other cases.

The invention also relates to a vehicle starter, in particular automobile, comprising an electric motor, a pinion driven said motor, means for moving said pinion to a position of rest at a position where it meshes with a crown of the heat engine, as well as a device of the aforementioned type for controlling the power supply of its electric motor.

• la figure 1 représente schématiquement un démarreur comportant un dispositif de commande conforme à un mode de réalisation possible de l'invention ;
• la figure 2 représente schématiquement un démarreur comportant un dispositif de commande conforme à un autre mode de réalisation possible pour l'invention.

Other characteristics and advantages of the invention will emerge from the description which follows, which is purely illustrative and non-limiting and which should be read with reference to the appended figures in which:

• FIG. 1 schematically represents a starter comprising a control device according to a possible embodiment of the invention;
• FIG. 2 diagrammatically represents a starter comprising a control device according to another possible embodiment for the invention.

The starter D shown in FIG. M electric and a power contactor 1.

This electric motor M is mounted between the mass and a terminal + Bat to the battery power supply.

The power contactor 1 is, in the particular example which is shown in the figure, a mechanical relay. It includes a contact mobile K, which is interposed between the supply terminal + Bat and the motor M, and a winding B whose feed moves the starter pinion and close the contact K.

This winding B is mounted between the + Bat terminal and the ground, in series with a controlled switch T1. This switch T1 is by example a MOSFET transistor whose gate is controlled by voltage by an output terminal s1 of a management unit 2.

A switch T2 is connected in parallel with the motor M, between two ends of it. This T2 switch is also controlled by the management unit 2. It is for example constituted by a transistor type MOSFET whose gate is voltage-controlled by an output terminal s2 of said management unit 2. A resistor R2 mounted between the grid of the transistor T2 and the ground puts said gate at the same potential as the source of the transistor T2 in the absence of signal on the output s2.

The management unit 2 is constituted by a microcontroller whose an analog input e1 is connected to the power supply terminal + Bat by via a switch 3, which constitutes the start switch of the vehicle.

• analyse de l'état ouvert ou fermé de l'interrupteur de démarrage 3 et gestion de la séquence d'alimentation du moteur M en fonction de cette information ;
• arrêt automatique du démarreur lorsque le moteur thermique est démarré ; protection du démarreur contre d'éventuelles surcharges ou fausses manoeuvres.

It provides different functions:

• analysis of the open or closed state of the start switch 3 and management of the power supply sequence of the motor M according to this information;
• automatic shutdown of the starter when the engine is started; protection of the starter against possible overloads or false maneuvers.

This management unit 2 is constantly powered up and is at this effect fed to the voltage delivered by the + Bat terminal via a link independent of the one on which the starter switch 3 is located. It incorporates a standby system, not shown, which allows limit electronic consumption when the vehicle is not running and This prevents the battery from being discharged too quickly.

The operation of the assembly which has just been described is the next.

When the start switch 3 is closed, for example by when the ignition key is actuated, the standby system is inhibited by the appearance of the voltage of the + Bat terminal on the input e1 of the management unit 2 and the startup sequence is activated.

If the different starter protection functions do not detect no anomaly, the output s1 of the electronic circuit delivers on the grid of T1 a modulated-width pulse voltage which supplies the coil B according to a current law. At first, the tension which is supplied controls the gate of transistor T1 so that a "current "high intensity" crosses the winding B to move the pinion starter and close the contact K. In a second step, when the pinion meshes with the heat engine and that the contact K is closed, the gate of transistor T1 is controlled so as to deliver winding B a "hold" current of lower intensity.

When the management unit 2 detects the engine start thermal, its output s1 goes low and blocks transistor T1, which disable the starter.

At the same time, its output s2 goes high, making the T2 transistor and thus shorting the electric motor M. As long as the armature turns, the starter runs as a generator. The kinetic energy of the rotor is dissipated by the Joule effect in the transistor T2, the armature of the motor M and the electrical connections. This results in a rapid braking of the armature.

It is however desirable that the deceleration is not too much brutal, so as to avoid the appearance of mechanical overloads accompanied by noises.

A first possibility for this purpose is to have in series with the transistor T2 additional resistance (not shown) allowing to reduce the short circuit current.

• soit répondre à une loi de variation mémorisée dans l'unité de gestion 2 (commande en boucle ouverte) ;
• soit réguler le courant de court-circuit en comparant la valeur instantanée de ce courant par rapport à une valeur de consigne (commande en boucle fermée), des moyens de type "shunt" (non représentés) permettant de transmettre sur une entrée analogique/numérique de l'unité de gestion 2 une tension proportionnelle à l'intensité du courant traversant le transistor T2.

Another solution consists in controlling the gate of transistor T2 with a pulse voltage with modulated width. The duty cycle of this control voltage can then:

• either respond to a variation law stored in the management unit 2 (open-loop control);
• or regulate the short-circuit current by comparing the instantaneous value of this current with a reference value (closed-loop control), shunt-type means (not shown) for transmitting on an analog / digital input of the management unit 2 a voltage proportional to the intensity of the current flowing through the transistor T2.

Other variants of the invention are of course possible.

In particular, in an advantageous variant, the contact K is replaced by a solid state relay, which is for example a MOSFET transistor of power whose gate is controlled by an output of the unit of management 2. The supply of the coil B then ensures that the displacement of the starter gear. A device for controlling the power supply of the electric motor of a starter having a static relay has already been described in patent application FR-98.11550 of the applicant, to which one will relate advantageously.

Alternatively also, as illustrated in Figure 2, the switch Contact 3 of the starter can directly control the contact K, instead to order it through the management unit 2.

In the example illustrated in FIG. 2, the relay 1 comprises two coils B1, B2, a common point of which is connected to the end of the contact switch 3 opposite the + Bat terminal. The end of the winding B1 opposite to this common point is connected to the mass, while the end B2 coil which is opposed to this common point is connected to a point between contact K and motor M.

In the same way as for the assembly of FIG. T2 MOSFET transistor is connected in parallel between the motor ends Mr.

The gate of this transistor T2 is voltage controlled by a output s1 of a management unit 2. It is also connected to the mass by via a resistor R2.

This management unit 2 is powered by the + Bat terminal. She receives on an input e1 the voltage at the end of the contact switch 3.

It receives on an input e2 the voltage of the terminal + Bat and on a input e3 the voltage at a point between the motor M and the power contact K.

Thus, the input e1 of the management unit 2 allows said unit to management to know the state (open or closed) of the ignition key 3.

The difference in voltage between the inputs e2 and e3 allows said management unit 2 to know the state (open or closed) of the contact of power K, compared to a reference threshold Vref.

When the contact switch 3 is closed, it settles in the coils B1 and B2 a current that generates a magnetic field of call for the contact K.

When the contact K is closed, the coil B2 is short-circuited, while the winding B1 carries out the maintenance of said power contact K in its closed position.

The transistor T2 is then controlled by the management unit 2 of way to be passing when the contact switch 3 and the contact of K power are open, and to be closed otherwise.

More precisely, the transistor T2 is controlled according to the following truth table:

Claims (10)

1. Device for controlling the power supply to the electric motor (M) of a starter (D) for a vehicle, particularly a motor vehicle, having a power switch (K) connected in series with the said electric motor (M), means (2, B) for controlling the said power switch (K), and an auxiliary switch (T2) which shorts the said electric motor when the power switch is opened, characterized in that the said auxiliary switch is a static electronic component (T2).
2. Device according Claim 1, characterized in that the power switch (K) is a static electronic power component.
3. Device according to one of Claims 1 and 2, characterized in that a static electronic component (T2) is a transistor.
4. Device according to one of Claims 1 to 3, characterized in that the auxiliary switch (T2) is controlled by a microcontroller (2) which manages the control of the power supply to the electric motor.
5. Device according to one of the preceding claims, characterized in that the static electronic component (T2) forming the auxiliary switch is connected in series with a resistor.
6. Device according to one of Claims 1 to 4, characterized in that the static electronic component (T2) forming the auxiliary switch is controlled by a pulse-width-modulated pulsed signal.
7. Device according to Claim 6, characterized in that the static electronic component (T2) forming the switch is controlled in open loop mode.
8. Device according to Claim 6, characterized in that the static electronic component (T2) forming the switch is controlled as a function of the strength of the current passing through it.
9. Device according to one of the preceding claims, characterized in that the power contact (K) of the starter is controlled directly by the vehicle's contact switch, and in that the said device has means for turning on the auxiliary switch (T2) when the contact switch (3) of the starter (D) and the power contact (K) are open, and for turning it off otherwise.
10. Starter for a vehicle, particularly a motor vehicle, having an electric motor, a gearwheel driven by the said motor, means for moving the said gearwheel from a position of rest to a position in which it engages with a ring gear on the thermal motor, a device for controlling the power supply to its electric motor, characterized in that this device is of the type according to one of the preceding claims.

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