DE4422636A1 - Automatic i.c. engine control for hybrid vehicle - Google Patents

Abstract

The engine control first allows power to be delivered by the i.c. engine when an operating parameter (v,n) proportional to the vehicle velocity reaches a defined min. value (v1,n1) in a first operating mode and in a second operating mode, allows the power to be delivered by the engine when the short-term overall power requirement (P) is above a threshold value. The delivery of power by the engine may be delayed for a given time interval when the overall power is above a continuous power threshold (P2) and below a short-term power threshold (P1).

Description

The invention relates to a method for automa control the delivery of performance through an internal combustion engine in motor vehicles with a Internal combustion engine, an electric motor and an electri Hybrid drive containing energy storage.

Such a method is known for example from the DE 41 33 014 A1 or known from DE 42 17 668 C1. At the method known from DE 41 33 014 A1 is a Hybrid drive provided that an internal combustion engine, a generator, an electrical energy storage in Form of an accumulator and at least one electric motor contains. Hybrid drives are also known which do not own generator but one that can be operated as a generator Ren electric motor.

The hybrid drive is controlled by an electronic control operated automatically. Are essentially two operating modes, the hybrid mode and the elec tro mode. In the electric mode under no circumstances does the engine operate instead, so that no exhaust emissions are released to the environment be. In the known from DE 41 33 014 A1 The electrical operating mode is used, for example, in City traffic selected. The electronic control unit knows the city traffic for example by the signal  a manually selectable switch or automatically by evaluating the frequency of braking and accelerating processes. However, in this known method depending on the state of charge of the energy storage at times the hybrid mode also in city traffic provided to by temporarily providing the Power through the internal combustion engine electrical Recharge energy storage. The hybrid mode is not only dependent on the battery charge but also depending on the Performance request by the driver or by others current vehicle parameters selected. The electrical loading drive mode and the hybrid mode are thus either which is activated manually or automatically. Especially with high performance requirements, for example with depressed accelerator pedal and switched on electric Ne consumers, the hybrid mode is preferred selected for additional electrical power or energy gie from the power or turning energy through the burning winning engine.

A particularly effective process for extracting electrical energy from the turning energy by the burning The engine is for example from DE 42 17 668 C1 known. In this known method there is no one of its own Generator provided, but the electric motor can Can also be operated as a generator. With this known method is the internal combustion engine generated excess torque for generating electrical energy gie by acting as a generator exploited the electric motor. In general, hybrid driven as little power as possible by the internal combustion engine engine may be necessary to reduce emissions as little as possible to generate.

It is an object of the invention to begin with a method to improve the type mentioned so that the need the provision of power by the internal combustion engine seems minimized, but sufficient provision the total service requested is guaranteed.

This task is characterized by the characteristics of the Claims 1 to 4 solved.

According to claim 1 is Lei in a first mode of operation Power from the internal combustion engine at the earliest when Errei Chen a predetermined minimum value of one of the vehicles speed-proportional operating parameters posed.

A proportional to the vehicle speed The driving parameter is, for example, the vehicle speed the speed itself, or the speed at which it turns Connection with the superimposed by the gear setting ratio also the vehicle speed can be determined. The minimum value of the vehicle speed The proportional operating parameter is preferred so specified that before reaching this min minimum values, especially at the start of the journey or at loading acceleration from a standstill, from the electric Energy storage available power is still large is greater than the power requested for the drive. Thus, an unnecessary switching on of the internal combustion engine machine with sufficient electrical power the electrical energy storage prevented.

According to the subject matter of claim 2 is in a second Operating mode power by the internal combustion engine be provided if a total performance above one Short-term power limit is requested.

The total output corresponds to the total electrical power stung, in particular for the drive and the utilities  electrical auxiliary consumers is requested. The power requested for the drive is in particular signaled by the position of the accelerator pedal. For example, there is the kick-down signal from the accelerator pedal before, at the driver's request, the maximum possible Drive power closed. For example alone as a requested total service be defined within a short-term power limit. The However, short-term performance limits do not have to be exclusive defined depending on the position of the accelerator pedal but can also depend on the battery The charging state is variable as the maximum possible for one certain total deliverable electrical power be true. The short-term power limit is general an electrical power value that is above the value one permanently degraded from the electrical energy storage their continuous output is. With the Ver drive according to claim 2 is thus Lei immediately if necessary Power provided by the internal combustion engine if the power requirement higher than that by the electri power storage is currently available power.

In the method according to claim 3, in a third Operating mode power through the internal combustion engine delayed a given amount of time if a total performance above a permanent performance limit and below half a short-term power limit is requested.

The continuous power limit is preferably defined in this way niert that this is the performance of the electrical Energy storage is permanently dispensable. For definition the short-term power limit will refer to the explanations Claim 2 referred. Will a total performance between the two defined performance limits for a long time as the specified time period is requested, performance becomes provided by the internal combustion engine. The above The time period is preferably dependent on  different operating parameters, such as. B. the Temperature, the state of charge and the age of the electri energy storage or the frequency and duration of the Continuous performance limit exceeded within one given period. Also with this invention Performance by the internal combustion engine is not unnecessary Provided wisely, but still guaranteed with him higher performance requirement the required performance.

According to claim 4, in a fourth mode of operation when the state of charge of the electrical energy storage a lower limit has dropped, performance by the Internal combustion engine provided until an upper The state of charge has been reached again.

To complete discharge of electrical energy Preventing memory becomes recharge Engine power provided, however not only until the lower limit is exceeded again but until a long-term one good state of charge is guaranteed again. Thus a constant switching on and off of the internal combustion engine prevented with partially discharged energy storage, whereby increased exhaust emissions due to frequent switch-on processes be prevented.

Thus, all subjects of claims 1 to 4 to utilize the power through the internal combustion engine machine with high efficiency, for permanent readiness provision of sufficient electrical power and Minimizing exhaust emissions.

An advantageous development of the invention is the Ge subject matter of claim 5, in which the various Be modes of operation according to claims 1 to 4 with difference priority can be selected. Thus, the ver different modes of operation are combined in such a way that  depending on the most advantageous mode of operation from the current emission requirement, the Consumption, comfort or the performance requirement is chosen.

Another advantageous embodiment of the invention is the subject of claim 6, wherein the internal combustion engine appear earlier than to to provide the necessary service desired time is started. Is the one you want Known point in time at which power by internal combustion Machine is to be provided, the internal combustion machine started earlier to timely To ensure provision of the required service most. The difference between the desired time and the predetermined earlier time is preferred the start time from the start of the engine to to ability to deliver performance, starting time for example from the cooling water temperature, the Kataly temperature or service life since the last time set the internal combustion engine depends.

In addition, it is pointed out that the fiction Appropriate procedures for hybrid drives of all kinds applicable is, e.g. B. independent of a serial or parallel Arrangement regardless of the number of electric motors and regardless of whether your own generator or a also provided as a generator operable electric motor is.

Exemplary embodiments of the invention are shown in the drawing shown. It shows

Fig. 1 shows the course of the required performance in depen dependence on the speed of the electric motor or by the vehicle speed in comparison with the provided electrical power of said electric energy storage device in the form of a battery

Fig. 2 shows two possibilities for providing Lei stung by the internal combustion engine in Depending speed of increased power requirement,

Fig. 3, the provision of power by the internal combustion engine depending on the battery charge state.

In Fig. 1, the rotational speed is n on the abscissa of the electric motor and the vehicle speed v and the electric power P shown on the ordinate. In the example according to FIG. 1, the electrical energy for secondary consumers is neglected. The total power requested here corresponds to the electrical power P _A , which is required for the drive by at least one electric motor. The electrical power P _B represents the electrical power available through the electric motor in connection with the electrical energy store or the battery. The requested electrical power P _A increases in the lower speed range with the speed n or the vehicle speed v. The requested power P _A and the available power P _B are at the speed n₁ or at the driving speed v₁ the same. For speed or driving speed values which are greater than the values n 1 and v 1, the requested power P _{A is} greater than the power P _B available in the long term through the battery. According to the invention, the rotational speed value n 1 or the vehicle speed value v 1 is preferably specified as the minimum value of the operating parameter proportional to the vehicle speed, before reaching which the power of the internal combustion engine is not yet to be provided. However, it is also possible to change their vehicle speed value, e.g. B. the permissible maximum speed in play streets, to prescribe such a minimum value. Preferably, the internal combustion engine can already be started at the predetermined earlier point in time at the vehicle speed value v₀ or the speed value n₀, so that when he reaches the vehicle speed v₁ or the speed n₁ the power required from then can be reliably provided. This ensures a steady acceleration. Since the necessary starting time between the start of the engine and its ability to deliver power can be determined empirically and also a characteristic speed or speed curve over time can be predetermined, the speed v₀ or the speed n₀ at which the engine can be started must, in order to be able to provide the required power at he range the speed v 1 or the speed n 1, can be determined in a simple manner. The characteristic speed curve over time can, for example, also be adaptively determined by means of the electronic control unit, in particular as a function of the current speed, power, acceleration and vehicle inclination.

Is the electrical power of the energy storage for the provision of the total service required off, power is provided by the internal combustion engine provides, either by a specially provided for it generator or by the generator acting as a generator Electric motor converted into electrical power and so with to drive or to charge the electrical energy memory used as additional electrical power becomes. To provide performance through the burning The engine can start and shut it off automatically be switched.  

In FIG. 2, the ordinate is the electric Gesamtlei stung P t and the time plotted on the abscissa. Fig. 2 shows two examples for providing Lei stung by the internal combustion engine in response to the requested total power P.

In the first example, the internal combustion engine is started or power is provided by the internal combustion engine provides if the requested total performance Power limit P2 exceeded for a certain time t1 ten, but is still below the short-term lei performance limit P1. According to the invention, if a requested total power P, which is at for example from the number of electri switched on secondary consumers and from the signal from the accelerator pedal results, for a long time between the continuous power limit P2 and the short-term power limit P1, Power by the internal combustion engine to the predetermined Time period t1 provided with a delay. The permanent lei The power limit P2 is preferably the power that the could give up electrical energy storage permanently, without additional power from the internal combustion engine seem to have to be supported.

In the second example, power is determined by the internal combustion engine preferably provided immediately when the on required total power the short-term power limit P1 has exceeded. The short-term power limit P1 can for example, be defined so that they are already the accelerator pedal kick-down signal has been exceeded. However, it can also be defined as total power P. to those who have just closed for a very short time switch the power to the internal combustion engine Can be made available.  

In the first example, the predefined one can be used Time period t1 with increasing total amount requested take off and when a requested Ge is reached total power with the value of the short-term power limit P1 become zero. In addition, the given time span t1 also depending on other operating conditions stands, such as B. the temperature, the state of charge and the age of the battery. He can also Start of the internal combustion engine shortly before the end of Period t1 be made so that the complete Provision of power by the internal combustion engine after the period t1 is guaranteed.

Fig. 3 is a graph showing the battery charge in% over time t. A lower limit SOC1 and an upper limit SOC2 are entered on the ordinate. If the battery state of charge drops below the lower limit SOC1, the internal combustion engine is started in order to output power and to charge or relieve the battery. The lower limit SOC1 can be dependent on current operating parameters of the battery and the vehicle, such as, for. B. the battery temperature, the outside temperature, the power requirement of the drive averaged over a certain time, the power requirement of the auxiliary consumers, the vehicle mass and the driving resistance.

Performance by the internal combustion engine will be provided until the battery charge level is the upper one Has reached limit SOC2. This upper limit is SOC2 preferably less than the maximum allowable loading capacity stood and in turn depends on various current issues len operating parameters such. B. the power requirement, the vehicle speed, the battery temperature, the current vehicle mass or the current Driving resistance.  

Basically, for reasons of emissions, the internal combustion engine always operate a certain minimum term. This minimum term can also depend on the service may, the driving speed, the battery charge level or the catalyst temperature.

If the starting time of the internal combustion engine is neglected, the start of the internal combustion engine can be equal to the ready Provision of power by the internal combustion engine be set. However, in each embodiment also a certain start time can be assumed, whereby the start of the internal combustion engine by a predetermined one earlier than when it was deployed required performance at the desired time if the desired time can be calculated.

In the following, the procedure for Start of the internal combustion engine received. All lie Starting conditions before, the engine can be started be tested. The following processes take place:

• - Turn on
  All systems required to operate the internal combustion engine are activated; e.g. B. the electronic control unit is supplied with voltage.
• - Waiting period
  After switching on the ignition, a waiting period expires, which is used to put the systems in the operating state and to be able to carry out self-tests if necessary. The waiting time can depend on various operating parameters, such as. B. depending on the operating mode of the systems before switching on (off, stand by, sleep), depending on whether there is a start to the journey or the start takes place during a journey or depending on feedback from systems, e.g. B. that the self-test was completed po sitiv or that the catalyst was heated to a required temperature, or that flaps and valves in the air, cooling water or exhaust system were adjusted according to the requirements.
• - Start of the internal combustion engine
  The internal combustion engine is accelerated to a starting speed which is below the idling speed of the internal combustion engine by means of a starter or the generator operated in engine operation. The speed curve of the acceleration process can be controlled depending on the driver's request or the operating state of the internal combustion engine.
• - Start of operation of the internal combustion engine
  With the beginning of the operating process of the internal combustion engine, the speed is increased further. If the actual speed exceeds the starting speed, the starting process is ended and the internal combustion engine runs on its own.
• - Accelerate to the operating speed
  The internal combustion engine is accelerated to the operating speed, taking into account emission and consumption values, depending on the driver's wishes and the operating state under zero load or under increasing load.
• - Abort the start process
  If the starting speed is not exceeded after a specified time, which is dependent on current operating parameters, this is considered an unsuccessful attempt to start and the start is aborted.
• - Repeat start
  After an unsuccessful start attempt, further start attempts can be made after a waiting break. The parameters in these retry attempts can be varied with each retry attempt in such a way that a higher probability of starting is ensured; e.g. B. the start time and the cranking speed can be increased. The number of permitted start attempts is limited. If the internal combustion engine cannot be operated even after several attempts to start, this can be signaled to the driver as a warning.

Claims (6)

1. A method for the automatic control of the provision of power by an internal combustion engine in motor vehicles with an internal combustion engine, an electric motor and an electric energy storage containing hybrid drive, characterized in that in a first mode of operation, power through the internal combustion engine at the earliest when reached a predetermined minimum value (v₁, n₁) of an operating parameter proportional to the vehicle speed (v, n) is provided. 2. Procedure for automatic control of the ready provision of power by an internal combustion engine schine in motor vehicles with a Brenn engine, an electric motor and an elec trical energy storage containing hybrid drove, characterized in that in a two Performance through the internal combustion engine machine is provided when a total stung (P) above a short-term power limit (P1) is requested.   3. Procedure for automatic control of the ready provision of power by an internal combustion engine schine in motor vehicles with a Brenn engine, an electric motor and an elec trical energy storage containing hybrid drove, characterized in that in a third Performance through the internal combustion engine line delay by a predetermined period of time (t1) device is provided when a total performance (P) above a continuous power limit (P2) and below a short-term power limit (P1) is required. 4. Procedure for automatic control of the ready provision of power by an internal combustion engine schine in motor vehicles with a Brenn engine, an electric motor and an elec trical energy storage containing hybrid drove, characterized in that in a four operating mode when the charge level of the elec trical energy storage (battery charge level) has dropped to a lower limit (SOC1), Lei Stung by the internal combustion engine as long as ready is set until an upper limit (SOC2) of the Charge status is reached again. 5. The method according to any one of claims 1 to 4, characterized in that the various Be drive modes with different priority are selectable.   6. The method according to any one of claims 1 to 5, characterized in that the internal combustion engine at a given time (v₀, n₀) before to provide the required performance desired time (v₁, n₁) is started.