EP2665921A1

EP2665921A1 - Method for automatically stopping an internal combustion engine of a motor vehicle

Info

Publication number: EP2665921A1
Application number: EP11793671.6A
Authority: EP
Inventors: Werner Bernzen
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2011-01-19
Filing date: 2011-12-08
Publication date: 2013-11-27
Also published as: CN103328811A; DE102011009001B4; DE102011009001A1; WO2012097840A1; US20140005914A1; JP2014506644A

Abstract

The invention relates to a method for automatically stopping an internal combustion engine of a motor vehicle, the method comprising: stop conditions as prerequisites for carrying out automatic stops of the internal combustion engine, and stop prevention conditions as prerequisites for preventing automatic stops of the internal combustion engine. An automatic stop of the internal combustion engine takes place when all stop conditions are met and none of the stop prevention conditions is met. According to the invention, one of the stop prevention conditions is an activated danger status (GS), wherein the danger status (GS) is activated when an acute indication (AI) exists. According to the invention, after the acute indication (AI) has ended, the danger status (GS) remains activated until a safety indication (SI) exists such that maneuverability of the motor vehicle by means of the internal combustion engine remaining switched on is maintained at least until the safety indication (SI) is detected.

Description

Method for automatically stopping an internal combustion engine of a motor vehicle

The invention relates to a method for automatically stopping a

Internal combustion engine of a motor vehicle according to the preamble of claim 1.

It is known that modern motor vehicles have so-called stop-start systems, by means of which an internal combustion engine of the motor vehicle is automatically stopped and started after a driver-initiated manual starting during a driving cycle. The automatic stop is usually carried out when the internal combustion engine is operated at idle and no torque of the internal combustion engine is required for propulsion of the motor vehicle or for a power take-off. The automatic start usually takes place when a

Torque request is made to the internal combustion engine - either by the driver via an accelerator pedal or by a PTO such as a

Air conditioning. Method for automatically stopping and / or starting a

An internal combustion engine by means of a stop-start system therefore includes such stop conditions and start conditions. In addition, such methods also include stop prevention conditions. Such stop prevention conditions cause an automatic stop of the engine is prevented, although the other stop conditions are met. An example of one

Stop prevention condition is the condition of an open hood - that is, an automatic stop of the engine is prevented for safety reasons on the condition that the hood of the vehicle is open. See, for example, DE 102 11 466 C1.

JP 2001-032734 A describes a method for automatically stopping an internal combustion engine of a motor vehicle, in which on the condition that, for example by an anti-lock braking system, locking of the wheels of

Motor vehicle was detected, an automatic stopping of the engine is prevented. This stop prevention is active as long as the blockage is present. By This stop-preventing condition is to be avoided that locked wheels of the motor vehicle, that is wheels with a wheel speed of zero, are erroneously interpreted by the stop-start system as a vehicle standstill. A vehicle standstill is a situation in which no drive torque is needed, and thus a situation in which a stop-start system as possible stops the engine.

In the mentioned method, there is the problem that safety aspects, in particular the aspect of a risk of collision, are disregarded. It is therefore the object of the present invention to provide a method for automatically stopping an internal combustion engine of a motor vehicle, which allows an improved behavior of the motor vehicle to avoid collisions.

The object is achieved by a method having the features of claim 1.

Advantageous developments of the method are the subject of the dependent claims.

The method for automatically stopping an internal combustion engine

Motor vehicle is characterized in that the internal combustion engine is automatically stopped when, as necessary, but not necessarily sufficient condition, certain stop conditions are met. These stop conditions include, for example

a coolant temperature of the internal combustion engine which is above a threshold,

a vehicle speed which is below a threshold,

a battery voltage that is above a threshold,

- An operation of a brake, wherein an operating level is above a threshold.

Another condition for the automatic stop of the internal combustion engine is a non-existence of a stop prevention condition. A stop-preventing condition is when one of the following exemplified criteria is satisfied

- a bonnet is open,

a vehicle door is open,

- a parking maneuver is under way.

In the presence of at least one of the criteria of the stop-preventing condition, an automatic stop of the internal combustion engine is inhibited according to the method, even if all of the above-mentioned stop conditions are met. In addition to the above examples, according to the invention, at least one of the criteria of the stop-prevention condition is an active danger status.

By the danger status is meant a status information indicating whether, according to predetermined evaluation criteria, there is a danger or not. The hazard status can have two values: an active hazard status indicates a detection of the hazard, an inactive or deactivated hazard status indicates an absence of the hazard. The danger is essentially a situation in which there is an increased probability that the motor vehicle collides with another motor vehicle or with an obstacle, or that the motor vehicle tilts or overturns. From the beginning to the end of the dangerous situation, it is desirable for the driving force of the motor vehicle to remain dynamically available. If the internal combustion engine would switch off automatically during the dangerous situation, then the structure of a required drive torque would be due to a

delayed automatic startup. During the danger situation, both a driver of the motor vehicle and an automatic safety system of the

Motor vehicle for the purpose of collision avoidance or for the purpose of changing a movement of the vehicle request a drive torque. The invention is intended to ensure that such a torque request in the motor vehicle with a stop-start system, a rapid torque build-up of

Internal combustion engine follows.

According to the hazard situation is divided into two successive phases, namely an acute phase and a latency phase. Both phases are determined on the basis of suitable criteria. The acute phase is based on acute criteria, which indicate with a very high probability the existence of the danger. The latency phase is based on latency criteria, which with a lower

Probability as the likelihood of the acute phase to indicate the presence of the hazard, or which are very likely to indicate a lower risk.

If the acute criteria are met, an acute indication is activated according to the invention. By acute indication is meant status information indicating whether, according to the acute criteria, an acute phase is present or not. If the acute criteria are not fulfilled, ie if there is no acute phase, the acute indication is deactivated, ie there is no acute indication. If the acute criteria are fulfilled, ie if an acute phase is present, the acute indication is activated, ie there is an acute indication. The hazard status is activated when an acute indication is activated and the danger status remains activated as long as the acute indication is active. Immediately after an acute phase, ie immediately after deactivation of the acute indication, the danger status remains activated, since, according to the invention, at least one further condition must be met in addition to the deactivation of the acute indication in order to deactivate the danger status. This additional condition is activation of a security indication. By the security indication is meant a status information indicating whether, according to suitable security criteria, it can be concluded that there is a very high probability that there is no longer any danger. The safety criteria include not only the negated acute criteria but other criteria. The presence of the security indication means an active security indication and a

Absence of danger.

A first advantageous development of the method provides that the

There is a safety indication under the minimum requirement that the acute indication has ended and thereafter a predetermined time has elapsed. Immediately after

Termination of the acute indication is a certain probability that one

State, which caused the acute indication, re-enters. This likelihood decreases after a certain time after the termination of the acute indication. Therefore, it makes sense for security, the security indication only after the

activate after the deactivation of the acute indication. The predetermined time is expediently in the range of a few seconds, preferably 5 to 10 seconds.

A further advantageous embodiment of the method provides that the

Safety indication under the minimum condition is present that the acute indication has ended and then the motor vehicle has traveled a certain distance. If the particular distance has been covered without the acute indication having been activated again, it can be assumed that with a large amount of time

Probability the danger is permanently ended. A meaningful one

Distance is in the range of a few hundred meters to a few kilometers.

The beginning of the acute phase, that is to say a change from a normal operating mode or normal operating environment of the motor vehicle to a dangerous mode of operation or a dangerous operating environment of the motor vehicle, is advantageously derived from measurable variables, in dependence on the measurable variables Hazardous conditions are set up and these hazard conditions are monitored. If at least one hazard condition exists, then the acute phase is present, that is, the acute indication is activated. Different types of hazards with different hazard conditions may underlie different types of acute indications. Upon fulfillment of any of the hazard conditions, the

Acute indication activated. In addition, any type of hazard advantageously has specific criteria for activating a particular security indication.

A further advantageous development of the method accordingly provides that one type of acute indication is an acceleration indication, wherein the

Acceleration indication is enabled under the minimum requirement that an amount of vehicle acceleration in one direction is greater than a first

Acceleration Threshold is and the safety indication is below the

The minimum requirement is that at least the amount of vehicle acceleration in one direction is less than a second acceleration limit value, wherein the second acceleration limit value is less than or equal to the first acceleration limit value. In this way, a dangerous situation due to exceeding the first acceleration limit value of the motor vehicle is detected. A meaningful first

Acceleration limit is 5 to 10 m / s ² , particularly advantageous is a first acceleration limit of 8 m / s ² . An end of the danger situation is not already at a fall below the first acceleration limit, but only when the second acceleration limit, z. B. 3 m / s ² , is reached, recognized.

A further advantageous development provides that a further type of acute indication is a lateral acceleration indication, wherein the lateral acceleration indication is activated under the minimum requirement that an amount of one

Vehicle lateral acceleration is greater than a first lateral acceleration limit and the safety indication is under the minimum requirement that the amount of vehicle lateral acceleration is less than a second lateral acceleration limit, wherein the second lateral acceleration limit is less than or equal to the first lateral acceleration limit. With the lateral acceleration is meant an acceleration of the motor vehicle transversely to the direction of travel.

A detection of a transverse acceleration of the motor vehicle, which is greater than the first lateral acceleration limit, indicates a skid or drift movement of the motor vehicle and is therefore a clear indication of a dangerous situation. A permanent termination of this type of dangerous situation can be assumed with a particularly high probability, if after a shortfall of the first Transverse acceleration limit is additionally undershot a second lateral acceleration threshold, wherein the second lateral acceleration limit is lower than the first lateral acceleration limit.

A further advantageous embodiment provides that a further type of acute indication is a control indication, wherein the control indication is activated under the minimum requirement that understeer or oversteer of the motor vehicle has been detected and the safety indication is present under the minimum requirement that for a predetermined time and / or a predetermined route no understeer and no oversteer of the motor vehicle is detected. With the understeer is a

Behavior of the motor vehicle meant, in which the motor vehicle drives a larger radius of curvature than corresponds to the chosen front wheels of the motor vehicle. In the oversteer, the motor vehicle drives a smaller radius of curvature than corresponds to the chosen front wheels. The control indication is thus activated when it is detected that the motor vehicle is moving in a direction other than the direction desired by the driver of the motor vehicle. Understeer and oversteer can be accomplished in a manner known to those skilled in the art

Vehicle dynamics system can be detected.

A further advantageous embodiment provides that another type of acute indication is a steering indication, wherein the steering indication is activated under the minimum requirement that a fast steering movement was detected at high speed and the safety indication is activated under the minimum requirement that for a certain time no fast steering movement is detected. Advantageously, the steering indication when exceeding a first limit for a

Steering speed activated and the safety indication is activated only when falling below a second limit of the steering speed.

A further advantageous development provides that a further type of acute indication is a target braking indication, wherein the target braking indication is under the

Minimum requirement is enabled that a radar-based target braking is performed. Information about the existence of target braking may be obtained from corresponding known safety systems.

A further advantageous development provides that a further type of acute indication is a brake indication, wherein the brake indication is activated under the minimum requirement that full braking and / or autonomous braking are performed becomes. In the case of full braking or autonomous braking, the safety is increased by the fact that during the full braking or autonomous braking and for a certain time or distance afterwards an engine stop

Activation of the stop prevention condition is omitted and so the vehicle remains as good as possible maneuverable.

A further advantageous development provides that a further type of acute indication is a collision indication, wherein the collision indication under the

Minimum requirement is activated that a collision hazard is detected. The danger of collision may be a danger of collision in the direction of travel or a collision risk on the side. The detection of a risk of collision can be done for example by a radar-based security system of the motor vehicle.

It is also advantageous, the acute indication depending on safety parameters of a vehicle dynamics control system or a

To activate the collision avoidance system. Such safety systems are designed to recognize dangerous situations of various kinds and to activate a danger status when the danger situation is detected.

The invention will be described in more detail with reference to the following description of embodiments and with reference to the accompanying drawings, from which further advantages and features.

Show

2 shows a flow diagram for a stop function of a stop-start system, FIG.

3 is a flowchart for a danger status function,

4 shows a flow chart for a safety function,

Fig. 1 shows a motor vehicle 1 for carrying out the method according to the invention. The motor vehicle 1 has an internal combustion engine 2, an engine control unit 3 for controlling and regulating the internal combustion engine 2 via control lines 9 and sensor lines 8, as well as a safety system 4. The security system 4 has a vehicle dynamics control unit 5 and an anti-collision control device 6, which are connected to one another via a data bus system 7 for the purpose of data exchange. The safety system 4 is connected to the engine control unit 3 via the data bus system 7. About the data bus system 7, the engine control unit 3 is not with others connected control units connected. The engine control unit 3 has a not-shown stop-start system, via which the internal combustion engine. 2

automatically stopped and started automatically. The stop-start system of the engine control unit 3 receives safety parameters via the data bus system 7 from the safety system 4, which are used for a function of the stop-start system.

FIG. 2 shows a flow chart for an engine stop function of the stop-start system. The engine stop function for automatically stopping the internal combustion engine 2 starts with a starting step 21. The starting step 21 includes preconditions, which are not shown, which must be fulfilled in order for the engine stop function to be able to function. After fulfilling the preconditions, a check is made for a stop condition 22. The stop condition 22 includes a check of several stop sub-conditions STB, which must be fulfilled in order for an automatic stop of the internal combustion engine 2 to take place. If the stop condition 22 is satisfied, it is checked if a

Stop prevention condition 23 is satisfied. The stop-preventing condition 23 includes checking a danger status GS. If the danger status GS is not activated, in a stop command step 24, a stop of the internal combustion engine 2 and then a return step 25 to the starting step 21.

If the stop condition 22 is not met, no stop occurs

Internal combustion engine 2, and the engine stop function begins after passing through the return step 25 again with the starting step 21. If the

Stop prevention condition 23 is met, there is also no stop of the

Internal combustion engine 2 and return to the starting step 21st

3 shows a flow chart for a hazard status function. The danger status function for evaluating the danger status GS begins with a starting step 31. The starting step 31 includes further preconditions, which are not shown, which must be fulfilled in order for the hazard status function to function properly. After fulfilling the further preconditions, an acute check step 32 is performed. The acute check step 32 includes a check of an acute indication AI. The acute indication AI is active in the presence of a hazard. If the acute indication AI is active, then follows a danger indicator 33, in which the danger status GS is activated. After the activation of the danger status GS, a return step 37 takes place to the start step 31. If a non-active acute indication AI is detected in the acute check step 32, the next step in a danger state check 34 is whether, from an earlier pass of the hazard status function, the danger status GS is activated. If the

Danger status GS is not activated, the return step 37 takes place. If the danger status GS is activated, a security status check 35 is carried out

Security status check 35 checks whether a security indication S1 is activated. If the security indication Sl is activated, then takes place in a

Hazard warning indication 36 deactivates the danger status GS and

then the return step 37. If it is determined in the security status check 35 that the security indication Sl is not activated, the remains

Danger status GS is activated and the return step 37 takes place to re-run the danger status function.

4 shows a flowchart for a safety function. A start step 41 of the safety function includes preconditions, which are not shown, which must be fulfilled in order for the safety function to function properly. After fulfillment of the preconditions, an acute condition step 42 takes place. In the acute condition step 42, an occurrence of a danger type is checked via an acute condition AI_Cond. If the acute condition AI_Cond is fulfilled, the acute indication AI is activated in an acute display 43 and at the same time the safety indication S1 is deactivated. Subsequently, a return step 47 takes place for a renewed passage of the safety function. If the acute condition AI_Cond is not met, deactivation 44 of the acute indication AI takes place. After deactivation 44 of the acute indication AI takes place

Security condition step 45, in which a security condition SI_Cond is checked. If the safety condition SI_Cond is fulfilled, then takes place in one

Safety display 46 an activation of the safety indication Sl. Is the

If the security condition SI_Cond is not met, then the return step 47 takes place. A deactivation of the security indication S1 takes place exclusively via the fulfillment of the acute condition AI_Cond. Non-fulfillment of the security condition SI_Cond alone does not lead to a deactivation of the security indication S1.

Each type of danger is associated with an acute indication AI, an acute condition AI_Cond and a safety condition SI_Cond. In the following, some hazard types and their acute conditions AI_Cond and safety conditions SI_Cond are listed by way of example:

- the type of danger is an over-acceleration, the associated acute indication AI is an acceleration indication; the acute condition AI_Cond is in this case is satisfied when a vehicle acceleration in one direction is greater than a first acceleration limit; the safety condition SI_Cond is satisfied in this case if the vehicle acceleration is less than a second

Acceleration limit is and if after deactivation 44 the

Acceleration indication has elapsed a certain time; the second

Acceleration limit is smaller than the first

Acceleration limit;

alternatively, the danger type is a lateral acceleration and the associated acute indication AI is a lateral acceleration indication; the acute condition AI_Cond is satisfied in this case when a vehicle lateral acceleration is greater than a first lateral acceleration limit value; the safety condition SI_Cond is satisfied in this case if the vehicle lateral acceleration is less than a second lateral acceleration limit value and if after the

Deactivation 44 of the lateral acceleration indication has elapsed a certain time; the second lateral acceleration limit is smaller than the first lateral acceleration limit;

- Alternatively, the danger is an over- or understeer of the motor vehicle 1 and the associated acute indication AI is a control indication; the

Acute condition AI_Cond is fulfilled in this case if an over- or

Understeer of the motor vehicle 1 has been detected; the safety condition SI_Cond is met in this case if the over- or understeer of the motor vehicle is no longer present and if after the deactivation 44 of the control indication a certain time has elapsed;

- Alternatively, the danger type is an avoidance situation of the motor vehicle 1 and the associated acute indication AI is a steering indication; the acute condition AI_Cond is satisfied in this case when a steering speed of the

Motor vehicle 1 is greater than a steering speed limit and a vehicle speed is greater than a vehicle speed limit; the security condition SI_Cond is fulfilled in this case if the

Steering speed of the motor vehicle 1 smaller than that

Steering speed limit and vehicle speed is less than the vehicle speed limit;

alternatively, the danger type is a first collision hazard and the associated acute indication AI is a target braking indication; the acute condition AI_Cond is fulfilled in this case when a target braking is performed by a safety system of the motor vehicle 1; the security condition SI_Cond is in this Case meets when the target braking is completed and when after the

Deactivation 44 of the target braking indication has elapsed a certain time;

- Alternatively, the danger is a second risk of collision and the associated acute indication AI an emergency braking indication; the acute condition AI_Cond is met in this case when a safety brake system of the motor vehicle 1 detects that emergency braking has been carried out; the safety condition SI_Cond is fulfilled in this case when the emergency braking is completed and after a certain time has elapsed after the deactivation 44 of the emergency brake indication;

- Alternatively, the danger is a third risk of collision and the associated acute indication AI a collision indication; the acute condition AI_Cond is fulfilled in this case if a collision danger, in particular a lateral risk of collision, is detected by a safety system of the motor vehicle 1, for example via associated radar sensors; the safety condition SI_Cond is fulfilled in this case when the risk of collision has passed and when a certain time has elapsed after deactivation 44 of the collision indication.

LIST OF REFERENCE NUMBERS

1 motor vehicle

2 internal combustion engine

3 engine control unit

4 security system

5 vehicle dynamics control unit

6 anti-collision control device

7 data bus system

8 sensor cables

9 control lines

21 Start step of engine stop function

22 stop condition

23 stop prevention condition

24 stop command step

25 Return step of the engine stop function

31 Starting step of the danger status function

32 acute examination step

33 danger indication

34 Risk status check

35 Security status check

36 danger alert indication

37 Return step of the danger status function

40 Schedule of the acute status function

41 Starting step of the safety function

42 acute condition step

43 Acute display

44 acute deactivation

45 safety condition step

46 safety indicator

47 Return step of the safety function

STB stop part conditions

GS danger status

AI acute indication

Sl security indication

AI_Cond acute condition

SI_Cond security condition

Claims

claims

1. A method for automatically stopping an internal combustion engine (2) of a motor vehicle (1), wherein

- an automatic stop of the internal combustion engine (2) is performed, if at least stop conditions (22) are met,

an automatic stop of the internal combustion engine (2) is prevented when a stop-prevention condition (23) is satisfied,

characterized in that

the stop-prevention condition (23) is met when a hazard status (GS) is active and the hazard status (GS) is activated when an acute indication (AI) is present,

- Wherein the danger status (GS) remains activated after a termination of the acute indication (AI) until a safety indication (S1) is present, so that a

Maneuverability of the motor vehicle (1) by means of the internal combustion engine (2) remaining switched on at least until the presence of the engine

Security indication (Sl) remains.

2. The method according to claim 1,

characterized in that

the safety indication (SI) is present under the minimum requirement that the acute indication (AI) has ended and thereafter a predetermined time has elapsed.

3. The method according to any one of claims 1 or 2,

characterized in that

the safety indication (SI) is present under the minimum requirement that the acute indication (AI) has ended and then the motor vehicle (1) has traveled a certain distance.

4. The method according to any one of claims 1 to 3, characterized in that

the acute indication (AI) is an acceleration indication, the

Acceleration indication (Bl) is activated under the minimum requirement that a vehicle acceleration in one direction is greater than a first

Acceleration limit is and the safety indication (Sl) under the

Minimum requirement is activated that at least the amount of

Vehicle acceleration is less than a second acceleration limit, wherein the second acceleration limit is less than or equal to the first acceleration limit.

5. The method according to any one of claims 1 to 4,

characterized in that

the acute indication (AI) is a lateral acceleration indication, the

Transverse acceleration indication is activated under the minimum requirement that an amount of vehicle lateral acceleration greater than a first

Is lateral acceleration limit and the safety indication (SL) is activated under the minimum requirement that the amount of

Vehicle lateral acceleration less than a second

Lateral acceleration limit, where the second

Lateral acceleration limit less than or equal to the first

Lateral acceleration limit is.

6. The method according to any one of claims 1 to 5,

characterized in that

the acute indication (AI) is a control indication, whereby the control indication is activated under the minimum requirement that an understeer or a

Oversteer of the motor vehicle (1) has been detected and the safety indication (Sl) is activated under the minimum requirement that no understeer and no oversteer of the motor vehicle (1) is detected for a predetermined time and / or a predetermined route.

7. The method according to any one of claims 1 to 6,

characterized in that

the acute indication (AI) is a guidance indication, the guidance indication being activated under the minimum requirement, a fast steering movement being detected at a high speed, and the safety indication (SI) below Minimum requirement is activated, that for a predetermined time no fast steering movement is detected at a high speed.

8. The method according to any one of claims 1 to 7,

characterized in that

the acute indication (AI) is a target braking indication, the

Target braking indication is activated under the minimum requirement that a radar-based target braking is performed.

9. The method according to any one of claims 1 to 8,

characterized in that

the acute indication (AI) is an emergency braking indication, wherein the emergency braking indication is activated under the minimum requirement that full braking and / or autonomous braking is performed.

10. The method according to any one of claims 1 to 9,

characterized in that

the acute indication (AI) is a collision indication, whereby the collision indication is activated under the minimum requirement that a collision hazard is detected.

11. The method according to any one of claims 1 to 10,

characterized in that

the acute indication (AI) depends on parameters of a vehicle dynamics control system and / or a collision avoidance system.