DE102009047163A1 - Circuit arrangement for a starting device - Google Patents

Abstract

A circuit arrangement (1) for an electrical machine (2), in particular a starter motor for starting an internal combustion engine (15) in a motor vehicle, with a current limiting device (3) for limiting an inrush current of the electrical machine (2) is described. In order to operate the electrical machine (2) as simply and resource-efficiently as possible, the circuit arrangement (1) comprises a bridging device (4) with a controllable switching device (5) for bridging the current limiting device (3).

Description

State of the art

The invention relates to a circuit arrangement for an electric machine, in particular a starter motor for starting an internal combustion engine, in a motor vehicle, with a current limiting device for limiting an inrush current of the electric machine. The invention also relates to a method for operating such a circuit arrangement.

Furthermore, the invention relates to a starting device for starting an internal combustion engine in a motor vehicle, with a, in particular the aforementioned, circuit arrangement and with a starter motor.

For starting internal combustion engines in motor vehicles starting devices are used, which are constructed with a starter motor on the principle of a DC machine with mechanical commutation, in particular as Außenpolmaschine.

In order to achieve a required high torque and high performance of the starter with a comparatively low vehicle electrical system voltage of about 12 V to 14 V, or 24 V to 28 V, the DC machine is equipped with a low number of turns and a large cable cross-section. Due to the resulting low impedance, that is about as a rotor or a stator, depending on the embodiment, the power loss is reduced and achieved a high torque output with relatively good efficiency. On the other hand, just the low impedance, and especially the low ohmic resistance, but also the low inductance, leads to high inrush currents and a temporary voltage dip in a battery-powered vehicle electrical system. Only with the start of the starter motor, a counter voltage is induced with increasing speed, which limits the current and thus counteracts the voltage dip. Additional consumers that are connected to the vehicle electrical system must be designed for this voltage dip or are deactivated at the time of the voltage dip.

In conventional starting systems, the voltage drop at the start is usually not critical, since additional consumers are mostly not yet active or inactive, or the temporary shutdown of a consumer is accepted. In starter-based start-stop systems in which the internal combustion engine is started by the starter motor even with additional active consumers, for example, after a short holding phase of the motor vehicle, increasingly higher demands are placed on a voltage maintenance in the electrical system. In order to provide a stable vehicle electrical system voltage, a second battery or a DC / DC converter is provided.

The DE 103 17 466 A1 describes a circuit arrangement with a starter motor of an internal combustion engine of a motor vehicle and with a series resistor connected in series to the starter resistor, namely an NTC series resistor whose resistance decreases with increasing temperature. When starting the starter motor, the NTC series resistor heats up and its resistance value decreases.

The DE 102 31 088 A1 describes a circuit arrangement of a starting device for an internal combustion engine of a motor vehicle with two series-connected transistors, wherein two resistors are connected as a voltage division in each case in parallel with a transistor to diagnose a short-circuit defect of the transistors in an off state of the transistors.

It is an object of the invention to provide a circuit arrangement, a method for operating the same and a starting device of the type described above in such a way that an electric machine is as simple as possible, resource-saving operation with the highest possible electrical system stability.

Disclosure of the invention

According to the invention the object is achieved by the subject matter of claims 1, 6 and 10. The dependent claims define preferred embodiments of the invention.

It is an idea of the invention that the circuit arrangement for an electrical machine comprises a bridging device with a controllable switching device for bypassing a current limiting device and which limits an inrush current of the electric machine when starting by means of the current limiting device and then the current limiting device is bridged with the bridging device. Thus, with the circuit arrangement, the inrush current of the electric machine can be limited and, in particular after a startup, the electric machine can be operated at full power by bridging the current limiting device so that a maximum current is achieved. Simply operate the electric machine with a current limiting device by the current limiting device can be deactivated by mere bridging. Furthermore, a resource-saving operation of the electrical machine is possible because of the Reduction of the voltage drop when starting the electric machine, the electrical machine is protected and a more dimensioned electrical supply, or even protective measures of other electrical consumers are avoided.

The controllable switching device can also be designed as an electromechanical switching relay or as an electronic switch, for example with a transistor. Thus, the bridging of the current limiting device and thus also the voltage drop can be controlled defined by switching the switching device. In addition, such a switching device is easy to control and cost feasible.

It is preferred that the electric machine is arranged in a motor vehicle and in particular is operated via a battery-powered vehicle electrical system. With the current limiting device, the electrical load of the electrical system can limit and still operate the electric machine by means of the lock-up device with a maximum power, so that the battery of the electrical system for a lower power, so resource-saving, dimensioned.

Preferably, the circuit arrangement for a starter motor for starting an internal combustion engine is formed in a motor vehicle, so that the electric machine is therefore a starter motor. To start an internal combustion engine, a high power is required, which is achieved in particular by a high current to the starter motor, resulting in a voltage drop of the electrical system results, which can be reduced by means of the current limiting device. Furthermore, the current limiting device can be bridged with the bridging device in order to be able to use a maximum starting torque during a cold start and / or the starting power after a breakaway of the motor.

Furthermore, it is preferred that the circuit arrangement is designed for a starter motor of a start-stop system, in which, for example, during short stop phases of the motor vehicle, the internal combustion engine is switched off and is switched on again for further travel, in particular fuel consumption and / or CO ₂ emissions to reduce.

In a start-stop system, with a short stop, so in particular when the engine is switched off, a vehicle electrical system consumers, such as a radio or control units of the motor vehicle, in operation and from the voltage dip, especially at a warm start, be affected. Due to the voltage dip, a short-term failure of the electrical system consumer can occur because it requires a certain minimum voltage in order to function safely. Such a failure is, for example, in a radio, at least undesirable or even represents a security risk, especially in a control device that prevents, for example, unintentional rolling away of the motor vehicle, namely a so-called ESP control unit with Hillhold function.

Conventionally, a second battery and / or a DC / DC converter installed in the electrical system to provide, at least selected electrical system consumers a stabilized voltage available. By the current limiting device, the inrush current of the starter motor can be limited during startup and the resulting voltage dip, at least to an uncritical level, can be reduced. On the second battery or the DC / DC converter can be omitted, so that the electrical system of the motor vehicle is resource-saving feasible. It is ensured by bridging the current limiting device that the engine can still be safely started with a full electrical power of the starter motor.

In a preferred embodiment, the current-limiting device comprises a start-up resistor limiting the inrush current of the electrical machine, in particular an ohmic resistor. The starting resistor can be connected in series with the electric machine and allows for low circuit complexity a resource-saving and cost-effective limitation of the current supply of the electric machine.

The starting resistance can be designed as a line resistance, in particular as an electrical supply line of the electrical machine, wherein it can be defined by a suitable choice of the line material, the line length and / or the line cross-section. This reduces the cost and assembly costs.

Preferably, the starting resistor is a discrete resistance element, in particular a metallic conductor. Such resistance elements are available in numerous designs, in particular with regard to their resistance value and their current carrying capacity, and permit a cost-effective and resource-saving realization of the circuit arrangement. In this case, a thermal design of the resistance element is particularly important, since in particular a starter motor is subjected to high current and also in a motor vehicle, the resistance element is exposed to large temperature fluctuations.

The starting resistor may be arranged in an engine compartment of the motor vehicle, so that it is easily accessible and easy assembly is possible. Preferably, the starting resistor is formed on the starter motor. The starting resistor and the starter motor can thus be manufactured in a cost-effective and resource-saving manner as a prefabricated, in particular coordinated, module and simply installed in a plurality of different motor vehicle platforms. In this sense, the controllable switching device and / or other components of the lock-up device in the engine compartment and also on the starting device, in particular on the starter motor can be arranged.

The starting of the electric machine takes a start-up period, which is determined in particular by a mechanical realization of the electric machine, the electric power and / or by a driven by the electric machine device, in particular the internal combustion engine of the motor vehicle. During the start-up period, the inrush current flowing through the electric machine, which causes the voltage drop, flows to the current supply. In a preferred embodiment, the current-limiting device can be bridged with the bridging device in a time-controlled manner, in particular after a current limiting period. A time control is simple and inexpensive, for example, as a switching delay or as a correspondingly slow switching time, in particular a relay feasible.

Preferably, with the current limiting device, the inrush current is essentially limited during the startup period, wherein, in particular, the startup duration essentially corresponds to the current limiting duration. Thus, the voltage drop can be reliably reduced and the electric machine operated as soon as possible after starting with a maximum electrical power by limited at startup of the inrush current and the lockup device, in particular synchronously to the end of the startup period, timed activated, so the current limiting device is bypassed.

As explained above, the voltage drop at the start of the electric machine is particularly high and decreases with increasing speed of the electric machine. Preferably, the current limiting device with the lock-up device is speed-controlled, in particular as a function of the rotational speed of the electric machine bridged, preferably so that when starting the electric machine, ie at low speeds, the energization of the electric machine with the current limiting device is limited and from a certain speed, the current limiting device with the lock-up device, in particular for a maximum current, is bridged. Thus, a simple and cost-effective start-up current limit can be realized. In this case, the current limiting device can be used particularly effectively, and in particular only until the electric machine has reached a certain speed, from which the voltage drop has fallen below a critical value. Incidentally, the current limiting device can also be bridged as a function of a rotational speed of the internal combustion engine, since this is coupled to the electric machine as a starter motor at least for starting.

According to a preferred embodiment, the bridging device, in particular the controllable switching device, is controlled by a control device, in particular time-controlled and / or speed-controlled. In this case, a control unit with a timer or a timer, that is, a timer as a time-control device for the current limit duration be designed to operate the lock-up device time-controlled, so to bridge the current limiting device time-controlled. In addition, but preferably alternatively, the controller may detect the rotational speed of the electric machine, for example by means of a sensor or as information from another control device to operate the lockup device speed controlled, so to bypass the current limiting device speed controlled.

The control unit may be integrated in the circuit arrangement, in particular in the lockup device, or, alternatively, as a, in any case already existing, start-stop control unit, engine control unit, on-board control unit or control unit of the electrical machine, in particular as a starter control unit, may be formed, optionally under Use of an additional relay for driving the lock-up device.

Further, the controller may be formed with a microcomputer and a computer program product to flexibly adapt, for example, the current limiting period during which the current limiting device is bridged to different starting times or to bridge the current limiting device according to different speed specifications.

In a further preferred embodiment, the bridging device is positively controlled, so that no additional control or regulation, in particular as an additional electronic module or as a control unit, is necessary. This is a simple and cost-effective start-up current limiting feasible. The bridging device can also be positively controlled by the speed of the electric machine, as explained later.

In a further preferred embodiment, the bridging device is controlled by a voltage that drops in particular across the electric machine, in particular by the controllable switching device is switched by the voltage. A voltage as electrical variable can be used with little component effort easily and directly for switching the lock-up device. In this case, the voltage can be detected and evaluated with additional electronics or a control unit that is present in any case, in order to control the bridging device in a voltage-dependent manner, ie to bridge the current-limiting device in a voltage-dependent manner. Alternatively, the bridging device can be forcibly controlled by the voltage, for example by the controllable switching device being switched by the voltage, preferably directly, ie not by means of the control device.

Incidentally, the voltage drop across the electric machine as the operating variable may also be due to a voltage induced in the electric machine which increases with increasing speed. Since the voltage drop across the electric machine thus depends on its speed, the current limiting device can be bypassed simultaneously with forced and speed control with little component complexity.

It is preferred that a switch-on voltage, the overwriting of which switches the bridging device from an off to a switched-on state, amounts to at least 30% and / or at most 70% of a rated voltage of the electrical machine. This ensures that switches over the bridging device in a medium voltage range and especially a contact flutter, so unintentional switching at low voltage fluctuations, is prevented at a switched on or off rated voltage. Furthermore, it is ensured that the lock-up device remains switched off when the electric machine is turned on, and that a certain voltage is induced only at a certain rotational speed of the electric machine, which corresponds to the turn-on voltage of the lockup device, at which the current limiting device is bypassed.

Furthermore, it is preferred that a turn-off voltage, below which the lock-up device changes from a switched to a switched-off state, is at most 50% of a rated voltage of the electrical machine. This prevents that after switching on the lock-up device it is switched off unintentionally, since just from the bridging of the current limiting device results in an increased current flow and thus a voltage dip, the voltage can also fall below the turn-on. Preferably, the turn-off voltage is thus significantly lower, for example, at least 30% of the rated voltage of the electric machine, as the turn-on, to ensure safe switching on and off of the lock-up device. Thus, a quasi hysteresis in the voltage-controlled positive control of the lock-up device, a reliable switching of the lock-up device can be realized.

The turn-on and / or the turn-off can be defined by a mechanical or electronic nature of the lock-up device, especially in a switching relay as a controllable switching device by a suitable design of an iron circuit, a relay winding, an armature, a return spring or switching contacts.

Preferably, a working current of the switching relay is a maximum of 5 A, so that the electrical system of the motor vehicle is only slightly loaded by the switching relay and a voltage drop is reduced due to the switching of the switching relay.

As a preferred embodiment of the invention, as mentioned above, the lock-up device is switched by a voltage drop across the electric machine. In this case, the bridging device, in particular the controllable switching device can be set to an electrical potential on the electric machine, for example by being connected via an electrical line to a terminal of the starter motor, so that the energization of the switching device directly through the above the starter motor decreasing voltage is controlled. Such a circuit arrangement allows a simple, in particular without further electronic or electromechanical components realizable, switchable lock-up device.

The bridging device may have a series resistor connected in series with the controllable switching device, in particular with a relay coil of the switching relay, so that a switching point of the switching device can be adjusted via the setting resistor. If the bridging device is switched by a voltage, in particular by the voltage drop across the electric machine, the switching point of the bridging device can be switched by means of the Tuning adjustment defined or define defined, in particular with respect to the speed of the electric machine. In this case, the adjustment resistor with the controllable switching device, in particular with an internal resistance of the relay coil, acts as a voltage divider. The adjustment resistor may have a fixed or variable resistance value.

In a preferred embodiment, the bridging device is designed as a contact closer, namely for bridging the current limiting device in a switched, in particular energized, state of the bridging device. Then, the lock-up device must be turned on only after the inrush current of the electric machine has been limited, so that an additional voltage dip in the operation of the current limiting device is avoided by the energization of the lock-up device. Another advantage of the lock-up device as a contact closure is that during the start-up period, only the contact must remain open, so that the voltage limiting the current limiting device is not accidentally bypassed, for example by a switching relay as a controllable switching device unintentionally drops due to the voltage drop.

In this case, the bridging device, in particular the controllable switching device, preferably has a switching delay for closing, which essentially corresponds to the starting time. Thus, the lock-up device and the electric machine can simultaneously control, in particular energize, in which case the energization of the electric machine with the current limiting device is limited during the startup period and after the switching delay, the current limiting device is bridged by the then switching lockup device. As a result, the circuit arrangement resource-saving, namely, in particular without a timer control unit, can be realized.

As an alternative preferred embodiment, the lockup device is configured as a contact opener. Then, a contact of the lock-up device is preferably opened before the electric machine is energized to start. This can for example be realized by the contact of the lock-up device is opened in good time before the energizing of the electric machine or by the contact of the lock-up device faster openable, ie with a shorter switching time, is designed as a switching device for energizing the electric machine, so that the lock-up device can be controlled simultaneously with the electrical machine with low component costs.

Furthermore, the circuit arrangement can be realized in this embodiment so that the lock-up device must be energized only during start-up of the electric machine. Then, a larger electrical power is available for operation of the electric machine after startup. Incidentally, in each case one of the two aforementioned alternative embodiments for a, in particular speed-dependent, controlled by a voltage bridging device can be suitably selected.

According to a preferred embodiment, at a temperature below a temperature limit value, the current-limiting device is bridged with the bridging device, in particular when the electric machine starts, because the power required to start the internal combustion engine increases with increasing temperature. If the current-limiting device is already bridged when the electric machine starts up, that is to say if the electric machine is energized to a greater extent, a greater power or a higher torque is available when it starts up. In addition, as the temperature decreases, the performance of the supply battery decreases. Thus, in particular, at cold temperatures, ie at least below the selected temperature limit value, the starter motor can be operated from the beginning with a full main current for breaking the internal combustion engine from a standstill position. Thus, in a cold start with maximum power, namely without current limit, but at an increased voltage dip, the electric machine, so in particular the internal combustion engine, and turn on a warm start, in which in particular a start-stop system more electrical system consumers are turned on , realize a current limit to reduce a voltage dip.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations.

Brief description of the drawings

The invention will be explained in more detail below with reference to the drawings. Show it:

1 a starting device with a circuit arrangement,

2 another starting device with a circuit arrangement,

3 another circuit arrangement,

4 another circuit arrangement and

5 a flowchart for a method for operating the starting device or the circuit arrangement.

The 1 shows a starting device 17 for starting an internal combustion engine 15 in a motor vehicle, not shown, with a circuit arrangement 1 and a starter motor 2 as an electrical machine 2 , The starting device 17 further comprises a conventional starter relay 7 , in particular for switching on and off an energization of the starter motor 2 with a starter relay contact 11 is trained. The starter relay becomes one of the starter motor 2 driven starter pinion a ring gear of an internal combustion engine is fed to start them.

The circuit arrangement 1 is with a current limiting device 3 Namely, a current limiting starting resistor, for limiting an inrush current of the starter motor 2 educated. Furthermore, the circuit arrangement comprises 1 a lock-up device 4 for bypassing the current limiting device 3 with a switching relay 5 as a controllable switching device. In this case, the circuit arrangement 1 from a control unit already present in the motor vehicle 16 controlled for a start-stop control, which includes the energization of the starter motor 2 via the starter relay 7 controls. The control unit 16 indicates for the circuit arrangement 1 its own connection interface. As alternative embodiments, the circuit arrangement 1 be controlled by an ignition switch or a start button in an instrument panel of the motor vehicle.

The starting resistance 3 limits an inrush current of the starter motor 2 by the starting resistance 3 virtually as a series resistor in series with the starter motor 2 is switched, in particular, only the inrush current is limited, as will be explained later. The starting resistance 3 is designed as a commercially available discrete resistance element based on a metallic conductor.

The switching relay 5 the lock-up device 4 is designed as a contact closer, namely for bridging the starting resistance 3 in a switched on, energized state of the switching relay 5 in which a switching relay contact 12 closed is.

In this embodiment, the starter relay 7 in conventional construction with a feeder 14 and a holding winding 13 trained and shared with the starter motor 2 arranged in an engine compartment of the motor vehicle, wherein the starting device 17 is designed for example as a push-screw drive starter.

At the beginning of a starting process of the internal combustion engine 15 is the bridging device 4 through the control unit 16 disabled so that the switching relay 5 not energized and the switching relay contact 12 is open. The starter relay 7 through the control unit 16 controlled to the starter relay contact 11 close and the starter motor 2 from a battery 10 to energize, so turn it on. As a result, the inrush current over the starting resistance 3 limited and a voltage dip in a vehicle electrical system 18 reduced. Incidentally, by tightening the starter relay 7 , not shown, the starter motor 2 with a starter pinion in a ring gear of the internal combustion engine 15 meshed in for a mechanical coupling.

With the beginning of the energization, namely the beginning of a start-up period of the starter motor 2 , Increases its speed increasingly, while the inrush current increasingly decreases, to a point in time, from which even without a current limiting the voltage dip would not exceed an undesirable level and determines the end of the startup period. Therefore, after a certain current limit period since switching on the starter motor 2 , essentially after the start-up period, from the controller 16 the lock-up device 4 timed by means of a timer control of the controller 16 activated, namely the switching relay contact 12 closed. Thus, the current limiting device 3 bridged to the starter motor 2 with maximum power from the battery 10 to energize.

As an alternative, not shown, embodiments, the controller 16 also a speed of the starter motor 2 determine, for example with a speed sensor or by evaluating a voltage at a terminal KL45 of the starter motor 2 , Then the lock-up device 4 be controlled, so the switching relay 5 to close the switching relay contact 12 be energized as soon as a certain speed is reached.

Another, not shown, embodiment differs from that in the 1 represented by the fact that the switching relay 5 as a contact closer not via the control unit 16 but directly by a voltage at the terminal KL50 or alternatively at the terminal KL45 is controlled. Furthermore, the switching relay 5 with a sufficiently long switching delay, which essentially corresponds to the start-up duration, designed so that after the start of the energization of the starter motor 2 the switching relay contact 12 for bypassing the current limiting device 3 only after the Switching delay is quasi time-controlled closed. Thus, the inrush current can be limited and the current limiting device positively controlled and timed after a certain period of time, namely the switching delay, for maximum energization of the starter motor 2 bridged.

Alternatively, in another, not shown, embodiment, the switching relay 5 as a contact opener between the terminal 50 and the terminal KL45. Here is the switching relay 5 as explained later, is designed so that there is a short switching time for opening the switching relay contact 12 in particular shorter than a switching time of the starter relay 7 is. In addition, it is designed to close slowly enough with the switching delay to timed accordingly, namely substantially after the start-up period, the current limiting device 3 to bridge.

The 2 shows a starting device 17 for starting an internal combustion engine 15 in a motor vehicle, not shown, with a circuit arrangement 1 and a starter motor 2 , The circuit arrangement 1 is for an electric machine 2 namely, the starter motor 2 for starting the internal combustion engine 15 in the motor vehicle, with a current limiting device 3 namely, a starting resistor for limiting an inrush current of the starter motor 2 educated. The circuit arrangement 1 includes a lock-up device 4 namely a switching relay 5 and a setting resistor 6 for bridging a current limiting device 3 , namely the current limiting starting resistor. In this embodiment, the circuit arrangement comprises 1 the conventional starter relay 7 , in particular for switching on and off an energization of the starter motor 2 with a starter relay contact 11 is trained. In this case, the circuit arrangement 1 from a controller 16 controlled for a start-stop control, via a switching device 8th ultimately the energization of the starter motor 2 controls. As alternative embodiments, the switching device 8th be controlled via an ignition switch or a start button in an instrument panel of the motor vehicle.

The starting resistance 3 and the switching relay 5 are, as in the 1 described, designed as a discrete resistance element or as a contact closure. Also analogous to the 1 is the starter relay 7 with a pull-in winding and a holding winding 13 educated.

Unlike the 1 becomes the lock-up device 4 , in particular the switching relay 5 , not directly by the controller 16 controlled, but is, as explained later, realized positively controlled by a voltage.

To start the internal combustion engine 15 becomes the switching device 8th through the control unit 16 pressed, leaving the battery 10 a current path with the pull-in winding 14 , the starting resistance 3 and the starter motor 2 and a current path with the holding winding 13 be energized. Consequently, the starter relay pulls 7 on and the starter relay contact 11 will be closed. By tightening the starter relay 7 is also, not shown, the starter motor 2 with a starter pinion in a ring gear of the internal combustion engine 15 meshed in for a mechanical coupling. As soon as the starter relay contact 11 is closed, is also the pull-in winding 14 bridged and the current consumption of the starter relay 7 reduces, namely on the energization of the holding winding 13 , In addition, the starter motor 2 via the starter relay contact 11 and the starting resistance 3 energized and thus turns on, the inrush current by means of the starting resistance 3 is limited and thus a voltage drop is reduced.

This in series with the adjustment resistor 6 switched switching relays 5 is parallel to the starter motor 2 switched so that above the switching relay 5 with the adjustment resistor 6 about the same voltage as on the starter motor 2 is applied. When starting the starter motor 2 Only a small voltage drops over this and the switching relay 5 is open, so that the energization of the starter motor 2 over the starting resistance 3 is limited. With increasing speed of the starter motor 2 is increasingly induced in this voltage, which rises so high that a turn-on voltage of the switching relay 5 is reached. Consequently, the switching relay 5 increasingly energized and switches to an on state, so the starting resistance 3 by means of the switching relay contact 12 is bridged, the full available voltage when energizing the battery 10 on the starter motor 2 is switched and thus also a maximum current for the full starter power is available.

The switching relay 5 So it's through the over the starter motor 2 positively controlled down voltage, in such a way that from a certain speed of the starter motor 2 the starting resistance 3 is bridged. A suitable speed at which the lock-up device 4 , in particular the switching relay 5 , is switched, can be over the adjustment resistance 6 because it is connected to an internal resistance of the relay coil of the switching relay 5 a voltage divider on the starter motor 2 decreasing voltage forms, so that the ratio of the turn-on voltage of the switching relay 5 to the in the starter motor 2 can be adjusted induced voltage.

So in this embodiment, the lock-up device 4 speed-controlled trained, in dependence of the speed of the starter motor 2 , In this case, the switching relay 5 a comparison with the turn-on voltage significantly lower turn-off, so it does not occur in a further voltage dip immediately after bridging the starting resistance 3 lets go again, so the bridging device 4 is turned off accidentally.

At a termination of the startup process, ie an opening of the switching device 8th , the energization of the starter relay 7 , in particular the holding winding 13 , interrupted and the starter relay contact 11 open. After that, the switching relay drops 5 with a certain delay, because for the time being one of the outgoing, quasi-generically powered starter motor 2 induced voltage is applied. Then the arrangement is ready for the next start.

In this embodiment, a starter motor 2 with an electrical power between 1 kW and 2.5 kW preferred, in which case a starting resistance 3 between 2 mOhm and 20 mOhm. In addition, the turn-on voltage of the switching relay 5 about 60% and the turn-off voltage about 30% of the rated voltage of the starter motor 2 ,

The 3 shows a circuit diagram of a further, alternative circuit arrangement 1 the starting device 17 according to the 2 That's up to a simpler starter relay 7 with only one winding comprises the same components as the embodiment shown above. Such a simplified starter relay 7 can be produced in a resource-saving and cost-effective manner. Furthermore, apart from the intake winding 14 , the explanation of the 2 Unlimited to this embodiment too.

The 4 shows a circuit diagram of a further circuit arrangement 1 the starting device 17 according to the 2 for the starter motor 2 for starting the internal combustion engine 15 , In this embodiment, the switching relay 5 designed as a contact opener, ie the switching relay contact 12 is in the de-energized state of the switching relay 5 closed. Below are only the main differences to those in the 3 illustrated embodiment explained:
When closing the switching device 8th First, the switching relay 5 over the adjustment resistor 6 and a diode 9 by the starter motor, which is still stationary at this point in time, or then starting 2 energized through, so that the switching relay contact 12 opens and a bridging of the starting resistance 3 is canceled. Here is a switching time of the switching relay 5 significantly below a switching time of the starter relay 7 formed so that also when closing the switching device 8th energized starter relay 7 only after opening the switching relay contact 12 the starter relay contact 11 closes and the starter motor 2 above the starting resistance 3 from the battery 10 is energized.

As previously explained, the speed of the starter motor increases 2 induced an increasing voltage, so that in this circuit arrangement 1 increasingly the voltage at the switching relay 5 is reduced, in such a way that the turn-off voltage of the switching relay 5 is fallen short of. Consequently, the switching relay contact 12 opened, the bridging of the starting resistance 3 lifted and the starter motor 2 energized at the full available voltage, so that the full starter power is available. So is a current consumption of the switching relay 5 after starting the starter motor 2 reduced.

Upon termination of the starting operation by opening the switching device 8th prevents the diode 9 that the switching relay 5 over the still closed starter relay contact 11 is energized almost backwards and closes again. In addition, the diode prevents 9 in this case, that the starter relay 7 via the relay winding of the switching relay 5 continues to be energized and thereby goes into self-preservation.

Further, not shown embodiments differ from those previously illustrated in that the circuit arrangement 1 Having a temperature-dependent switch, the bridging of the starting resistance at a temperature below a certain limit 3 interrupts, so that at temperatures below this limit already at start, so from the beginning, the full voltage for a maximum current, so also a maximum power of the starter motor 2 is available.

The 5 shows a flowchart with steps of a method for operating the circuit arrangement 1 or the starting device 17 according to the 1 to 4 ,

In one step 40 is checked if a temperature of the starting device 17 falls below a certain threshold. If so, it will be done in one step 42 , the bridging device 4 otherwise, the lock-up device remains 4 in one step 41 switched off.

Subsequently, in one step 43 the starter motor 2 by closing the switching device 8th energized to turn this on, in Dependency of the preceding steps at a temperature of at least the limit of the inrush current from the current limiting device 3 is limited and at a temperature below the limit, the current limiting device 3 from the beginning of the energization of the starter motor 2 with the lock-up device 4 is bridged, so that it is operated at maximum power at the expense of a maximum voltage dip.

In one step 44 is quasi checked during start-up of the starter motor by means of a positive control, whether a certain speed of the starter motor 2 is achieved by the lock-up device 4 from one above the starter motor 2 decreasing voltage is controlled. If this is true, so is the turning of the starter motor 2 completed with the inrush current, is in one step 45 the lock-up device 4 forcibly switched on, or remains switched on, if it was already switched on due to the temperature condition. Finally, in one step 46 the starter motor 2 with bridged current limiting device 3 for full power without current limiting to start the engine 15 operated. All figures show only schematic not to scale representations. Incidentally, reference is made in particular to the drawings for the invention as essential.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10317466 A1 [0006]
• DE 10231088 A1 [0007]

Claims (10)

Circuit arrangement ( 1 ) for an electric machine ( 2 ), in particular a starter motor ( 2 ) for starting an internal combustion engine ( 15 ), in a motor vehicle, with a current limiting device ( 3 ) for limiting an inrush current of the electric machine ( 2 ), characterized in that the circuit arrangement ( 1 ) a bridging device ( 4 ) with a controllable switching device ( 5 ) for bridging the current limiting device ( 3 ). Circuit arrangement ( 1 ) according to claim 1, characterized in that the current limiting device ( 3 ) one the inrush current of the electric machine ( 2 ) includes current limiting starting resistance. Circuit arrangement ( 1 ) according to claim 2, characterized in that the starting resistance ( 3 ) is a discrete resistance element, in particular a metallic conductor. Circuit arrangement ( 1 ) according to one of claims 1 to 3, characterized in that the bridging device ( 4 ) is designed as a contact closure. Circuit arrangement ( 1 ) according to one of claims 1 to 4, characterized in that the bridging device ( 4 ) is designed as a contact opener. Method for operating a circuit arrangement ( 1 ), in particular according to one of claims 1 to 5, for an electrical machine ( 2 ), in particular a starter motor ( 2 ) for starting an internal combustion engine ( 15 ), in a motor vehicle, with a current limiting device ( 3 ) for limiting an inrush current of the electric machine ( 2 ), characterized in that the circuit arrangement ( 1 ) a bridging device ( 4 ) with a controllable switching device ( 5 ) for bridging the current limiting device ( 3 ) and that the inrush current of the electric machine ( 2 ) when starting by means of the current limiting device ( 3 ) and then the current limiting device ( 3 ) with the bridging device ( 4 ) is bridged. Method according to Claim 6, characterized in that the current-limiting device ( 3 ) with the bridging device ( 4 ) is time-controlled, in particular after a current limiting period, bridged. Method according to Claim 6 or 7, characterized in that the current-limiting device ( 3 ) with the bridging device ( 4 ) speed-controlled, in particular in dependence on a rotational speed of the electric machine ( 2 ) is bridged. Method according to one of claims 6 to 8, characterized in that the bridging device ( 4 ) by a voltage, in particular over the electrical machine ( 2 ) is controlled, in particular by the controllable switching device ( 5 ) is switched by the voltage. Starting device ( 17 ) for starting an internal combustion engine ( 15 ) in a motor vehicle, with a circuit arrangement ( 1 ), in particular according to one of claims 1 to 5, and with a starter motor ( 2 ), characterized in that the circuit arrangement ( 1 ) a current limiting device ( 3 ) for limiting an inrush current of the starter motor ( 2 ) and a bridging device ( 4 ) with a controllable switching device ( 5 ) for bridging the current limiting device ( 3 ) and that the starting device ( 17 ) is designed in particular for a method according to one of claims 6 to 9.

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