DE10100889B4 - Method and device for realizing a start / stop operation in vehicles - Google Patents

Abstract

A method for ensuring the power supply in a vehicle with start / stop operation, in which alternate engine run times and engine downtime, the power supply during engine downtime using two sub-supply networks, each containing an energy storage, the energy required for a start or warm start supplied by the first of the two partial supply networks, the energy required for the electrical system consumers is supplied by the second partial supply network, during the motor downtime, the voltage level of the energy store contained in the first partial supply network is monitored and included in the second partial supply network board consumers so long from the first partial supply network are fully co-supplied until the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold value, and wherein, when the voltage ngsniveau of the energy store contained in the first partial supply network falls below the predetermined first threshold, which is limited to the supply of the second partial supply network charging current is limited, wherein when the voltage level of the energy store contained in the first partial supply network falls below a second predetermined threshold, which is smaller than the first threshold, a shutdown of not necessarily required electrical system consumers takes place.

Description

The invention relates to a method and an apparatus for realizing a start / stop operation in vehicles.

State of the art

From the WO 98/19890 an on-board control unit is known, which has a power supply, a short-circuit proof power amplifier, a control and regulating unit and a DC-DC converter. This onboard power supply control unit is connected between the onboard power supply battery and the starter battery of a motor vehicle. In this case, the starter battery can be supplied as needed via the DC-DC converter from the vehicle electrical system side so that both a higher and a lower or the same charge voltage level compared to the vehicle electrical system voltage can be generated by temperature. In this known Bordnetzsteuergert be provided via the switch provided there 14a and 14b in the case of an empty electrical system battery both batteries connected in parallel. This can lead to the starter battery being discharged very far, so that the required battery power is not always ensured in the case of shortly successive starting operations.

From the DE 34 23 663 A1 For example, a device for starting and stopping an internal combustion engine provided with a starting engine in a vehicle is known. In this known device, the internal combustion engine is turned off in the presence of a definable combination of input variables and / or switching states and restarted upon actuation of at least one switch by turning on the starter motor. In addition, in the case of the known device, a starting operation is also carried out with the simultaneous presence of a driving speed of the vehicle over a predefinable limit value and actuation of the vehicle brake pedal. This ensures the maintenance of the brake vacuum of the power brake when the vehicle is rolling, but only if the driver is responsive and presses the brake pedal with his foot.

The citation DE 38 41 769 C1 describes a circuit arrangement for ensuring the starting energy in motor vehicles with internal combustion engines. In this case, the voltage of the starting battery is monitored after a standstill of the on-board generator. If an adjustable voltage limit is undershot, the starter battery is disconnected from the electrical system via a voltage-controlled relay switch. Hints to the effect of limiting the charge current transmitted to the supply of the second partial supply network when the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold value, DE 38 41 769 C1 can not be deduced.

The citation DE 198 46 319 C1 describes a power supply circuit for a motor vehicle electrical system with two power supply branches, wherein the first power supply branch via a DC-DC converter from the second power supply branch and the second power supply branch is fed by a generator. By using separate energy storage in conjunction with a switched by a vehicle electrical system management suitable operation, the starting safety of the motor vehicle is increased. To ensure start-up reliability, the aim is not to burden the second energy store with quiescent current. For this purpose, with the internal combustion engine switched off, the DC-DC converter is normally switched to blocked, which prevents a discharge of the energy store at the expense of the starting energy. Hints to the effect of limiting the charge current transmitted to the supply of the second partial supply network when the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold value, DE 198 46 319 C1 can not be deduced.

The citation DE 196 45 944 A1 describes a control unit for a vehicle electrical system with at least two rechargeable batteries from a generator, which serve to supply various consumers. The controller is located between the two batteries and opens or closes the connection between the two batteries and goes into a sleep mode after switching off. The battery provided for the starter supply can be supplied as required by a DC-DC converter from the electrical system side so that both a higher and a lower or the same charging voltage level compared to the vehicle electrical system voltage can be realized. The use of a suitable voltage converter allows a charge of the starter battery when the on-board battery is relatively heavily discharged. Indications to the effect of limiting the charging current transmitted to the supply of the second partial supply network when the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold value, DE 196 45 944 A1 can not be deduced.

The citation DE 196 28 222 A1 describes a device for power supply in a motor vehicle with a supply circuit comprising at least one generator, a first battery and consumer, and with a Start circuit comprising a second battery, which is associated with the starter and is connectable via switching means to the generator and the first battery comprises. An onboard power supply control unit comprises an onboard power supply module, which performs the required switching operations, and has a connection via which startup and operationally necessary onboard power supply components can be supplied with voltage. These on-board network components are supplied with the highest priority and are supplied with too strong a discharge of the supply battery from the starter battery, thereby ensuring that during a boot process, the other electrical system components are not connected to the starter battery. Hints to the effect of limiting the charge current transmitted to the supply of the second partial supply network when the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold value, DE 196 28 222 A1 can not be deduced.

The citation DE 197 05 610 A1 describes a drive unit for an internal combustion engine that performs a different starting method when the engine is cold than when the engine is warm. The drive unit is equipped with a starter and a starter / generator machine. To start the cold engine, the starter is activated together with the starter / generator machine and to start the warm engine, which is in start-stop operation and in fly-pay mode, the starter-generator machine alone.

Starting from the prior art, the task arises to ensure a more stable power supply in the start-stop operation of the vehicle without affecting the start-stop function. This object is solved by the features of the main claims.

Advantages of the invention

The method according to the invention with the features of claim 1 has the advantage that in the start / stop operation of the vehicle, a more stable power supply is ensured without affecting the start / stop function. This is achieved in that the power supply during the engine downtime using two partial supply networks is carried out, each containing an energy storage. The state of charge of the energy store of the partial supply network, which serves to supply the starter or starter generator, can be controlled in such a way that the energy necessary for starting the vehicle is always present. During the engine running time after a warm start, a charge deficit arising in the energy storage can be compensated quickly.

For this purpose is located in an advantageous manner in the partial supply network, which serves to supply the starter or starter generator, also provided for charging the energy storage of this partial supply network generator. This can be an independent generator or the starter generator for the start itself. Such starter generators can be realized on the basis of a claw-pole machine with belt drive or on the basis of an asynchronous machine or synchronous machine. In the event that the starter generator can not afford the start, an additional starter must be provided in one of the two partial supply networks. In determining the charging strategy or the charging characteristic for the energy storage of the sub-supply network, which serves to power the starter or starter need to be taken in an advantageous manner no consideration for any restrictions and specifications of other individual consumers, as in this sub-supply either no other individual consumers or only against voltage fluctuations insensitive additional consumers are provided. In particular, the charging strategy can be such that the energy store is charged in a short time by means of a high charging voltage. This ensures that even at low outside temperatures and frequent start / stop operations, the energy required to start the engine is available.

A charging of the energy storage of the second partial supply network, which preferably contains the electrical system battery of the vehicle is carried out during the engine run times via a DC-DC converter also from the generator or starter generator, through which the starter battery is charged. During engine downtimes, the on-board power supply battery can be co-supplied by the starter battery until the state of charge of the starter battery falls below a predetermined threshold value. By means of the onboard power supply battery during the engine downtime to a minimum reduced consumers in the electrical system are supplied with energy, such as lighting. Only when the voltage level necessary for the supply of the starter can just be provided by the starter battery, the supply of the vehicle power supply battery is interrupted. To slow down the discharge process of both batteries gradually individual on-board consumers can be switched off depending on the voltage level of the starter battery.

To further optimize the charging or recharging strategy of the energy storage in the sub-supply networks, a control device is preferably used, which energy storage state signals, consumer status signals and temperature sensor signals are supplied. This Control unit may be centrally located, integrated in the DC-DC converter or be provided this or be arranged in the region of the generator or one of the batteries.

drawing

An embodiment of the invention is illustrated in the drawing and will be explained in more detail in the following description. The 1 shows a schematic representation of a first embodiment of the invention. The 2 shows a schematic representation of a second embodiment of the invention. The 3 shows a more detailed representation of the second embodiment, in which a control device is illustrated.

description

The 1 shows a schematic representation of a first embodiment of the invention. In this case, the power supply in start / stop operation, in which alternate engine run times and engine downtime and in which between a motor stop time interval and an engine running time interval, a warm start of the vehicle is carried out as follows:
A starter generator SG, for example a 42 V starter generator, and a battery B1, for example a 36 V battery, form a first partial supply network 1 , The starter generator SG is provided for performing the warm start. Consequently, in the partial supply network 2 a separate starter is provided for the cold start. Consequently, the battery B1 serves primarily to provide the energy required for a warm start. If the starter generator SG also takes the cold start, the battery B1 is also designed for cold start and the starter in the partial supply network 2 can be omitted.

An on-board battery B2, for example a 12 V battery, is part of a second partial supply network 2 , This is for supplying a starter AN and for supplying consumers V, such as lighting, radiator fan, ..., provided. The possibly additional starter AN is only required for a cold start and is therefore of no significance for start / stop operation. Consequently, the battery B2 must provide the energy needed for a cold start and, with activated start / stop operation, both during the engine downtime and during the engine run times, the consumers V to power.

In a first embodiment of the in 1 the first embodiment shown are the two partial supply networks 1 and 2 during start / stop operation during engine downtimes completely decoupled from each other. The battery B1 only has the task of providing the energy required for the next warm start of the vehicle for the starter generator SG. Other consumers are not powered from the battery B1 during engine downtime. The battery B2 has the task during the engine downtime, the consumer V, for example, a car radio, light and various control units to provide energy.

During the engine run times, the batteries B1 and B2 are recharged. This recharging takes place using the energy generated by the starter generator SG during the engine running times.

Since no further consumers are provided in the partial supply network in which the battery B1 is located, the recharging of this battery B1 can take place rapidly by means of a charging strategy or charging characteristic optimized with regard to the specific type of battery used. It does not take any consideration of any restrictions and specifications from other consumers. By this to the respective battery type optimized recharge of the battery B1 is achieved in an advantageous manner that in start / stop operation at low outdoor temperatures, the duration of the motor run times required between two engine downtime can be shorter than in known solutions. In such known solutions, in which the charging strategy must be determined with regard to other consumers, only a relatively small charge current consumption can take place, resulting in a comparatively long charging process.

The recharge of the partial supply network 2 arranged battery B2, which is the vehicle electrical system battery of the vehicle, via the DC-DC converter 3 , the two partial supply networks 1 and 2 only for the purpose of this recharge the battery B2 coupled during the engine running times.

In a second embodiment of the in 1 In the embodiment shown, in the start / stop mode, during the engine stoppage times, the battery B2 is switched via the DC-DC converter 3 so long unrestricted mitversorgt until the voltage level of the first partial supply network 1 arranged battery B1 reaches a predetermined first threshold. This first threshold value is selected to be high enough to ensure that the energy required for a warm start can be provided by the battery B1 without problems.

If the voltage level of the battery B1 falls below the predetermined first threshold value, then the charge current transfer from the battery B1 via the DC-DC converter 3 limited to the battery B2 and thus accepted that the battery B2 continues to discharge.

If the voltage level of the battery B1 decreases further and falls below a second predetermined threshold, then the power consumption is reduced. This can be done by completely disabling low priority consumers in the sense of a priority list, or by reducing some or all consumers' power consumption. This slows down the discharge of both batteries.

If the voltage level of the battery B1 decreases further and falls below a third predetermined threshold, then the supply of the battery B2 via the DC-DC converter 3 interrupted. This third threshold value is set so that it is further ensured that the battery B1 can provide the energy required for a start for the starter generator SG.

If the voltage level of the battery drops so far that the execution of a warm start is no longer ensured, the start / stop function is suppressed.

This second embodiment is also distinguished by the fact that care is always taken to keep the charge state of the battery B1 high enough so that the energy required for a warm start for the starter generator can be provided in the start / stop mode after a motor standstill phase. As long as the state of charge of the battery B1 is significantly above this limit, in this embodiment, via the DC-DC converter 3 the second partial supply network 2 be taken care of. This supply can be gradually reduced depending on the voltage level of the battery B1.

Also in this embodiment, the batteries B1 and B2 are recharged in the start / stop operation during the engine running times. This recharging takes place using the energy generated by the starter generator SG during the engine run times, as already described above in connection with the first embodiment.

The 2 shows a schematic representation of a second embodiment of the invention. In this case, the power supply in the start / stop mode, in which alternate engine run times and engine downtime and in which between a motor stop time interval and an engine running time interval, a warm start of the vehicle takes place as follows:
A generator G, for example a 42 V generator, a battery B1, for example a 36 V battery, and the starter AN of the vehicle belong to a first partial supply network 1 of the vehicle. The starter AN is intended both for performing cold starts and warm starts. Consequently, the battery B1 serves primarily to supply the energy necessary for the starting processes of the vehicle.

An on-board battery B2, for example a 12 V battery, is part of a second partial supply network 2 , This is intended to supply the other onboard power consumers V, such as lighting, control units, .... This applies both during engine downtime and during engine runtimes.

In a first embodiment of the in 2 shown second embodiment, the two partial supply networks 1 and 2 during start / stop operation during engine downtimes completely decoupled from each other.

The battery B1 only has the task of providing the energy required for the next warm start of the vehicle for the starter AN. Other consumers are not powered from the battery B1 during engine downtime. The battery B2 has during the engine downtime, the task of providing the reduced to a minimum consumer V, such as a car radio, lights, control devices or a car phone with energy.

During the engine run times, the batteries B1 and B2 are recharged. This recharging takes place using the energy generated by the generator G during the engine running times.

Since no further consumers are provided in the partial supply network in which the battery B1 is located, the recharging of this battery B1 can take place rapidly by means of a charging strategy or charging characteristic optimized with regard to the specific type of battery used. No consideration for any restrictions and specifications needs to be obtained from other consumers. By this to the respective battery type optimized recharge of the battery B1 is achieved in an advantageous manner that in start / stop operation at low outdoor temperatures, the duration of the motor run times required between two engine downtime can be shorter than in known solutions. In such known solutions, in which the charging strategy must be determined with regard to other consumers, only a relatively small charge current consumption can take place.

The recharge of the partial supply network 2 arranged battery B2, which is the vehicle electrical system battery of the vehicle, via the DC-DC converter 3 , the two partial supply networks 1 and 2 only for the purpose of this recharge the battery B2 coupled during the engine running times.

In a second embodiment of the in 2 The exemplary embodiment shown in the start / stop mode during the engine downtime, the battery B2 via the DC-DC converter 3 so long unrestricted mitversorgt until the voltage level of the first partial supply network 1 arranged battery B1 reaches a predetermined first threshold. This first threshold value is selected to be high enough to ensure that the energy required for a warm start can be provided by the battery B1 without problems.

If the voltage level of the battery B1 falls below the predetermined first threshold value, then the charge current transfer from the battery B1 via the DC-DC converter 3 limited to the battery B2 and thus accepted that the battery B2 continues to discharge.

If the voltage level of the battery B1 decreases further and falls below a second predetermined threshold value, then the power consumption of some or all of the vehicle electrical system consumers is reduced. This can be done by completely disabling low priority consumers in the sense of a priority list, or by reducing some or all consumers' power consumption. This slows down the discharge of both batteries.

If the voltage level of the battery B1 decreases even further and falls below a third predetermined threshold, then the supply of the battery B2 via the DC-DC converter 3 interrupted. This third threshold value is set in such a way that it is further ensured that the battery B1 can make available the energy required for a start for the starter AN.

If the voltage level of the battery B1 drops so far that the execution of a start is no longer ensured, the start / stop function is suppressed.

This second embodiment is also distinguished by the fact that care is always taken to keep the state of charge of the battery B1 high enough so that the energy required for starting the starter can be provided in the start / stop mode after a motor standstill phase. As long as the state of charge of the battery B1 is significantly above this limit, in this embodiment, via the DC-DC converter 3 the second partial supply network 2 be taken care of. This supply can be gradually reduced depending on the voltage level of the battery B1.

Also in this embodiment, the batteries B1 and B2 are recharged in the start / stop operation during the engine running times. This recharging takes place using the energy generated by the generator G during the engine run times, as already described above in connection with the first embodiment.

The 3 shows a more detailed representation of the second embodiment, in which a control unit ST is illustrated. By means of this control unit ST, which in a corresponding manner also in the in the 1 shown embodiment, is by a controller of the generator G and the DC-DC converter 3 the recharging of the batteries B1 and B2 controlled. This is done using additional information that is supplied to the controller.

This additional information includes information about the state of charge and aging and the temperature of the batteries B1 and B2. Further additional information is consumer status signals and information about the state of the generator G. Furthermore, the controller ST also used to optimize the Nachladevargänge signals that are supplied to him via the vehicle bus CAN, for example, from the engine control unit, and signals that are derived from other sensors. Such additional sensors are, for example, temperature sensors for detecting the outside temperature and sensors for detecting the speed of movement of the vehicle.

In on-board electrical energy management systems, which will in future be designed as 14 V / 42 V vehicle electrical systems, and which may also be pure 42 V electrical systems, the control unit ST controls using the aforementioned additional information and information about the types the batteries B1 and B2, the generator G and the DC-DC converter 3 in the sense of an optimized charge of the batteries B1 and B2.

Thus, a dynamic adjustment of the energy flow between the two sub-supply networks depending on the type and number of consumers currently switched on. If, for example, currently no voltage-sensitive consumers are switched on and the motor is running, then the charging voltage can be increased, especially at low outside temperatures, without having to take consumers into account, so that the memory B2 can be recharged more quickly.

Furthermore, in the partial supply network 1 if there is a 42 V generator used there will also be 42 V consumers included. However, these may only be consumers who are insensitive to strong voltage fluctuations. This must therefore be taken into account, since a wide range of charging voltages should be permitted for a fast charge of the battery B1.

With regard to the positioning of the control unit, it is pointed out that the control unit can be centrally arranged in systems with electrical energy management. Furthermore, the controller can be provided to the DC-DC converter or integrated in this. Further, the controller may be located near the generator or near one of the batteries.

Claims (12)

A method for ensuring the power supply in a vehicle with start / stop operation, in which alternate engine run times and engine downtime, the power supply during engine downtime using two sub-supply networks, each containing an energy storage, the energy required for a start or warm start supplied by the first of the two partial supply networks, the energy required for the electrical system consumers is supplied by the second partial supply network, during the motor downtime, the voltage level of the energy store contained in the first partial supply network is monitored and included in the second partial supply network board consumers so long from the first partial supply network are fully co-supplied until the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold value, and wherein, when the voltage ngsniveau of the energy store contained in the first partial supply network falls below the predetermined first threshold, which is limited to the supply of the second partial supply network charging current is limited, wherein when the voltage level of the energy store contained in the first partial supply network falls below a second predetermined threshold, which is smaller than the first threshold, a shutdown of not necessarily required electrical system consumers takes place. A method according to claim 1, characterized in that batteries are used for energy storage. A method according to claim 1, characterized in that when the voltage level of the arranged in the first partial supply network energy storage device falls below a third predetermined threshold, which is smaller than the second threshold value, the supply of the second partial supply network is interrupted. Method according to one of the preceding claims, characterized in that the threshold values are predetermined depending on the temperature. Method according to one of the preceding claims, characterized in that the co-supply of the consumers contained in the second partial supply network from the first partial supply network via a DC-DC converter. Method according to one of the preceding claims, characterized in that during the engine run times the energy store contained in the first partial supply network is recharged using a generator also included in the first partial supply network. A method according to claim 6, characterized in that during the engine run times of the energy contained in the second partial supply network energy storage is recharged via the DC-DC converter using the generator contained in the first partial supply network. Method according to one of the preceding claims, characterized in that the power supply during the start / stop operation is controlled by a control unit, which energy storage state signals, consumer status signals and temperature sensor signals are supplied. Device for powering a vehicle with start / stop operation, in which alternate engine run times and engine downtime, with a first partial supply network ( 1 ) and a second partial supply network ( 2 Each having an energy storage (B1, B2), both power supply networks during the engine downtime serving for power supply, and with a control unit (ST) having input terminals for energy storage state signals, consumer status signals and temperature sensor signals and which is used to control the power supply during the Start / stop operation is used, in which the energy required for a start or warm start is supplied by the first of the two sub-supply networks, the energy required for the electrical system consumers supplied by the second sub-supply network, the device is designed such that during the engine downtime the Voltage level of the first Partial supply network contained energy storage is monitored and in the second partial supply network contained board network consumers are so long from the first partial supply network mitversorgt until the voltage level of the energy store contained in the first partial supply network falls below a predetermined first threshold, and wherein the device is designed such that when the voltage level the energy store contained in the first partial supply network falls below the predetermined first threshold value, the charge current transmitted to the second partial supply network is limited, the device being designed such that when the voltage level of the energy store contained in the first partial supply network falls below a second predetermined threshold, which is smaller is as the first threshold, a shutdown of non-essential electrical system consumers done. Apparatus according to claim 9, characterized in that the first partial supply network ( 1 ) a starter generator and the second partial supply network ( 2 ) additionally a starter (AN), z. B. for the cold start, has. Apparatus according to claim 9 or 10, characterized in that between the two partial supply networks, a DC-DC converter ( 3 ) is provided. Device according to one of claims 9 to 11, characterized in that the second partial supply network ( 2 ) As a component of the electrical system battery which serves to supply the electrical system consumers (V).

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