DE10036556B4 - Device for controlling the power supply of a starter for an internal combustion engine, in particular of a motor vehicle - Google Patents

Abstract

Device for controlling the power supply of an electric motor of a starter, in particular for motor vehicles, comprising a power contact (K) controlling the power supply of the electric motor of the starter, a circuit for controlling said power contact (K) and a contact switch (3) interposed between the control circuit and a terminal (B +) to the battery voltage, said device also comprises a safety switch (R) which prevents the power supply of the starter when one or more conditions are not met, characterized in that said safety switch ( R) is mounted between the ground and a point of the connection connecting the control circuit to the terminal (B +) to the battery voltage and to which the contact switch (3) belongs.

Description

The present invention relates to a device for controlling the power supply of a starter for an internal combustion engine, in particular of a motor vehicle.

In 1 a control circuit for the power supply of an electric motor M of a starter for the internal combustion engine of a motor vehicle is illustrated.

In general, the motor M is mounted between the ground and a supply terminal B + for connection to the battery voltage. The control circuit comprises a relay 1 which includes a power contact K connected between the terminal B + and the motor M, and a plurality of windings Ba and Bm which control the displacement and then the holding of the contact K in its closed position. At the in 1 In the illustrated example, the relay comprises two windings, a Ba forming a pull-in winding and a Bm forming a holding winding. The pull-in winding Ba is connected to the terminal B + via a control switch C, and its opposite end is connected to a point between the power contact K and the motor M. The holding coil Bm is in turn arranged between the ground and the control switch C.

When closing the control switch C, the power supply of the windings Ba and Bm controls the displacement of the power contact K and its closing, whereupon the power supply of the winding Bm causes the holding power contact K to be kept in the closed position.

The switch C may be the switch of the steering wheel lock of the vehicle or a relay, which in turn is operated by the ignition key or by an electronic system such as the control module of the engine. This switch C may be a mechanical contact or an electronic relay.

In such a control circuit, the starter is turned on by any unforeseen closure of the switch C, for example due to a failure of the electronic circuit which controls the closing of this switch. In this case, if the transmission is not idling, the vehicle will start, resulting in a very significant hazard to people and objects that are on its lane.

To avoid this risk, certain vehicles are equipped with one or more safety contacts, which are connected in series in the circuit of the vehicle.

An already known solution that in 2 is to connect such a contact S with the switch C in series between the supply terminal B + and the one or more windings of the power contact relay.

This contact S is closed only when the shift lever of the vehicle is in neutral position or when the clutch pedal is actuated.

This solution has the disadvantage that it requires a more complex and costly wiring, since the cable to the transmission or the clutch pedal must be declared before it reaches the starter.

In addition, then the two terminals of the safety contact S must be isolated. This results in corresponding additional costs for this component.

On the one hand because of the high currents (30 to 60 amperes), which are required for the control of the starter, and on the other hand due to the extension of the cable, the cross section of this cable must be increased in order to avoid an excessive voltage drop, which also additional costs caused.

From the AT 9 026 E For example, a starter assembly for internal combustion engines is known in which a safety switch is arranged in series with the starter relay. The DE 2 242 587 C3 shows a starting device with a park-neutral safety switch, which is connected in series with a starter solenoid. In the DE 87 08 510 U1 is provided an actuation of the starter suppressing safety switch, which is electrically in series with a switch provided for the starter operation.

Another, also known solution is to insert the contact S in the ground circuit of the starter. This will be in 3 illustrated.

The control logic is identical to the control logic described above.

For example, the WO 98/46877 A1 a starter starting system for an automatic transmission with a power contact that controls the power supply of an electric motor of the starter, wherein a relay for controlling the power contact is provided. There is a safety switch in series between the relay and ground arranged, which is switched in dependence of the position of a selector lever.

However, this solution also has certain disadvantages.

It requires an isolated mass at the starter. In addition, in this solution, it is necessary to use a high-power relay for the execution of the contact S.

Therefore, this solution is also associated with high additional costs.

The invention has for its object to provide a device for controlling the power supply of a starter, which is secured and does not have the disadvantages of the above-mentioned solutions. In particular, it is an object of the underlying invention to provide a cost-effective solution that can be realized with little effort.

To this end, the invention proposes a device for controlling the power supply of an electric motor of a starter, in particular for motor vehicles, comprising a power contact which controls the power supply of the electric motor of the starter, a circuit for the control of said power contact and a contact switch, between the control circuit and a connection to the battery voltage, said device further comprising a safety switch which inhibits the power supply of the starter when one or more conditions are not met, characterized in that said safety switch is mounted between the ground and a point of the connection is that connects the control circuit to the connection to the battery voltage and to which the contact switch belongs.

In particular, the safety switch is advantageously mounted between the ground and a point between the contact switch and the control circuit.

Such a device has an economical structure and eliminates the security problems following the unforeseen closing of the control contact. Above all, the safety switch can be inexpensive because it has a very low power and only one insulated terminal.

In addition, the wiring has a small cross-section, and the safety switch is connected to the rest of the control device through only one connecting wire, which also contributes to low cost of the device.

• – die bereits erörterte 1 eine schematische Darstellung einer Vorrichtung zur Steuerung der Stromversorgung eines Anlassers;
• – die ebenfalls bereits erörterte 2 eine schematische Darstellung einer gesicherten Vorrichtung zur Steuerung der Stromversorgung eines Anlassers, die nach dem Stand der Technik bekannt ist;
• – die ebenfalls bereits erörterte 3 eine schematische Darstellung einer anderen gesicherten Vorrichtung zur Steuerung der Stromversorgung eines Anlassers;

The features and advantages of the invention will become apparent from the following description. It should be read with reference to the accompanying drawings. In it show in detail:

• - those already discussed 1 a schematic representation of a device for controlling the power supply of a starter;
• - which also has already been discussed 2 a schematic representation of a secured device for controlling the power supply of a starter, which is known in the prior art;
• - which also has already been discussed 3 a schematic representation of another secure device for controlling the power supply of a starter;

4 a schematic representation of a secure device for controlling the power supply of a starter according to a possible embodiment of the invention;

the 5 and 6 an illustration of the conditions for the design of the elements of the device of 4 ,

In the 4 illustrated control circuit comprises a relay 1 , which includes a power contact K whose closing by the power supply of a winding 1a or controlled by windings Ba and Bm, as related to 1 have been described.

The power supply of this winding is in turn controlled by a switch C, which is a MOSFET transistor whose gate voltage is controlled by a control unit 2 is controlled.

This control unit 2 is done by closing a switch 3 activated, which is the contact switch of the vehicle (for example, ignition key switch). This is an input of said control unit 2 with a supply terminal B + for the supply of the battery voltage through the contact switch 3 connected.

A safety switch R is between the ground and a point between the contact switch 3 on the one hand and the control unit 2 on the other hand.

This safety switch R allows the activation input of the starter to be grounded when certain conditions are not met, for example when the gear lever is not in neutral or when the clutch pedal is not depressed.

Continuing the description, Z1 stands for the equivalent resistance of the branch, the said point via the contact switch 3 with the terminal B + connects, Z2 for the equivalent resistance of the branch, which connects the said point via the safety switch R to the ground, and Z3 for the equivalent resistance of the branch, the said point with the control unit 2 combines.

These equivalent resistances Z1, Z2 and Z3 are chosen so that the current Ic applied at the input e is greater than the minimum current Icmin required for the operation of the starter when the safety switch R is open ( 5 ) and when the battery voltage during the starting process assumes its minimum value Vbmin.

Z1 and Z3 therefore verify: Ic = Vbmin / (Z1 + Z3)> Icmin

In addition, these substitute resistors Z1, Z2 and Z3 should be chosen so that the current Ic applied to the input e is less than the minimum current Icmin when the safety switch is closed and when the battery voltage reaches its maximum value Vbmax ( 6 ).

Z1, Z2 and Z3 therefore verify: Ic = Vbmax * Z2 / (Z1 * Z2 + Z2 * Z3 + Z3 * Z1) <Icmin.

This solution is particularly advantageously used in the case of an electronic control starter which requires only a weak current for its activation.

It should be noted that in a preferred variant Z2 is chosen equal to 0, whereby the addition of a further component in the circuit is avoided. The contact and the resistance are therefore in turn chosen so that they can withstand a current equal to Vbmax / Z1.

Other variants than those described above may be considered. This may in particular be the control current of the control unit 2 to act on a pulse stream. In this case, the resistors Z1, Z2, Z3 are adjusted as a function of the frequency of the current accordingly.

The control unit of the control circuit is for example a microprocessor.

Claims (8)

Device for controlling the power supply of an electric motor of a starter, in particular for motor vehicles, comprising a power contact (K) which controls the power supply of the electric motor of the starter, a circuit for controlling said power contact (K) and a contact switch ( 3 ) mounted between the control circuit and a terminal (B +) to the battery voltage, said device further comprising a safety switch (R) which prevents the starter from supplying power when one or more conditions are not met, characterized in that said safety switch (R) is mounted between the ground and a point of the connection connecting the control circuit to the terminal (B +) to the battery voltage and to which the contact switch ( 3 ) belongs. Apparatus according to claim 1, characterized in that the safety switch (R) between the mass and a point between the contact switch ( 3 ) and the control circuit is mounted. Device according to claim 2, characterized in that the equivalent resistances: - of the branch which crosses said point via the contact switch ( 3 ) connecting to the terminal (B +) to the battery voltage, - the branch which connects the said point to the ground via the safety switch (R), - the branch which connects said point to the control circuit, which are referred to as Z1, Z2 and / or Z3, verify the following: Vbmin / (Z1 + Z3)> Icmin and Vbmax * Z2 / (Z1 * Z2 + Z2 * Z3 + Z3 * Z1) <Icmin, where Icmin is the minimum current required at the input of the control circuit for the operation of the starter, Vbmin and Vbmax being the maximum and minimum values which the supply voltage can assume. Apparatus according to claim 3, characterized in that Z2 is chosen equal to zero. Device according to one of the preceding claims, characterized in that the control current is a pulse current. Device according to one of the preceding claims, characterized in that the control circuit has a control unit ( 2 ), such as a microprocessor. Device according to Claim 6, characterized in that the said control unit ( 2 ) controls a transistor (C), in turn, the Power supply of one or more windings ( 1a ) of a relay ( 1 ) whose contact forms the power contact (K) which controls the electric motor of the starter. A unit comprising an electric motor of a starter, in particular for motor vehicles, and a device for controlling the power supply of said electric motor, characterized in that the said control device is designed according to one of the preceding claims.

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