EP2462016A2

EP2462016A2 - Method for controlling a rolling or coasting mode of a vehicle

Info

Publication number: EP2462016A2
Application number: EP10732363A
Authority: EP
Inventors: Joachim Staudinger; Ingo Sauter; Maik WÜRTHNER; Johannes Kemler
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2009-08-05
Filing date: 2010-07-14
Publication date: 2012-06-13
Also published as: DE102009028242A1; WO2011015430A3; WO2011015430A2

Abstract

The invention relates to a method for controlling a rolling or coasting mode of a vehicle, having a drivetrain having a drive motor, an automatic or automated transmission, and actuatable switching means for interrupting the frictional connection in the drivetrain. In order to allow driving operation using the rolling or coasting function that is as effective as possible but still comfortable, safe, and reliable, a frictional connection interruption in the drivetrain is released if the counter level (n) of a rolling or coasting mode counter drops below a prescribed first threshold (n neutral) or takes on the value of zero, wherein the rolling or coasting mode counter is incremented if at least one of the events stored in an event table occurs, and otherwise is decremented or maintained.

Description

Method for controlling a rolling or Seqelmodus a vehicle

The invention relates to a method for controlling a rolling or sailing mode of a vehicle, having a drive train with a drive motor, an automatic or automated transmission and controllable switching means for interrupting the frictional connection in the drive train, according to the preamble of patent claim 1.

In order to save energy and costs as well as to reduce the environmental impact, vehicles can be temporarily driven without drive in suitable driving situations in a rolling or sailing mode. In particular, in a motor vehicle in roll mode, the internal combustion engine can be operated as low as possible and with low emissions at idle while the vehicle is rolling with the drive train open. If the internal combustion engine is switched off in such a driving situation in order to increase the saving effect, the vehicle moves in a so-called sailing mode. These functions are already known.

The traction interruption can, depending on existing powertrain components and gearbox design, by a circuit of the transmission in neutral and / or by opening a startup clutch, as soon as a roll or sailing is possible. However, it has been found that the known methods for detecting suitable driving situations for the rolling or sailing mode either due to a rather unfiltered consideration of topographical conditions of the route and / or insufficient consideration of the current driving condition, the driving situation is not always interpreted correctly or are relatively complex and prone to errors, which can often lead to unnecessary or for the driver situational undesirable and possibly counterproductive neutral circuits or adhesion interruptions in the drive train. From DE 10 2007 001 936 A1 a method for controlling a clutch of an automatic transmission of a motor vehicle is known in which a mountain detection and a neutral idle control are continuously evaluated and tested. The method is performed in order to save fuel in idle conditions of the internal combustion engine, for example when stopping at signal systems or in stop-and-go operation, in a neutral position of the transmission. In addition, in a neutral gear of the transmission, a rollback of the vehicle to be prevented on a slope due to a low brake pressure to hold the vehicle.

For such neutral idle control, i. a situation-controlled neutral circuit, certain entry conditions must be met, which include an evaluation of a mountain detection flag and a mountain counter. A mountain detection flag can be set at a corresponding evaluation based on the mountain detection or a hill counter can be increased. This is the case when the transmission is in a forward gear, a transmission output speed is greater than a predetermined output speed limit, a throttle position of the internal combustion engine is less than a predetermined throttle position limit, a brake status indicates that the vehicle brake is applied, and the transmission temperature is within an allowable range is.

A non-coasting neutral idle circuit may occur when, at a transmission output speed that is less than the predetermined output speed limit, the current count is less than a predetermined counter limit or, at a count above that counter limit, when the brake pressure is greater than a pre-calculated brake pressure limit or, if Brake pressure is not available and the count is greater than the counter limit, if a mountain detection flag is set.

The known method uses continuously detected transmission, engine and brake data of the vehicle, which after evaluation via a Counter provide reliable signals for appropriate neutral circuits of the vehicle. The disadvantage of this, however, is that the use of the method is more limited to a stationary or nearly stationary vehicle, and thus not readily to the driving or accelerator pedal operation of the driver for taxiing or sailing on levels or downhill is transferable. In particular, the triggering of a neutral circuit during such a journey is not prevented in a rather unfavorable driving situation for the driver.

From DE 102 21 701 A1 a method for controlling a clutch of a motor vehicle with an automated transmission is known. The clutch is opened and thus the traction in the drive train is interrupted when an accelerator pedal or a brake pedal or in their effect corresponding control variables are not actuated with the engine running and a minimum travel speed. After opening the clutch, the transmission is switched to neutral so that the vehicle is in a roll mode. After actuation of the accelerator pedal or the brake pedal or by changing in their effect corresponding sizes, the clutch is closed again, thereby completing the rolling mode. Before closing the clutch, a speed synchronization of the driving internal combustion engine and a drive shaft of the transmission initially takes place in order to end the rolling mode as comfortably and quickly as possible. Furthermore, it is provided not to open the clutch and thus not to activate the roll mode when a need for an anticipated vehicle deceleration is detected. This can be the case, for example, with a fast gas removal or when selecting a sports program.

The disadvantage of this is that not always when the vehicle is neither downhill nor the gas or brake pedal is pressed, a sailing or rolling mode makes sense. In particular, predictive topographical, traffic situation-related or in-vehicle parameters are rather insufficiently considered in the method. The speed synchronization when terminating the roll mode is designed especially for automated transmissions. In addition, a combined sailing or rolling operation with an operation of a cruise control system or brake control system is not provided.

From DE 10 2004 017 1 15 A1 a method for automatic Fahrgeschwindigkeitsregelung- or driving speed and distance control for a vehicle with an automatic or automated transmission is known in which the driving speed can vary in the range of a preselected desired speed. This is followed in each case by an acceleration phase, a coasting phase in which the traction in the drive train can be interrupted to save fuel. In the sequence of acceleration and coasting phases, topographical data obtained by means of a navigation device, data from a monitoring device of the immediate vehicle environment and / or vehicle parameters can be taken into account. The acceleration phases can be assisted by an electric motor in addition to an internal combustion engine.

The known method uses a sailing or rolling mode, which is used to control the speed within a cruise control system, where a desired speed set by the driver or within an ACC (Adaptive Cruise Control) or ADR (Automatic Distance Regulation) system, in which Sensors, the vehicle environment is monitored in order to adjust the distance to the vehicle in front by automatically accelerating or decelerating using a brake control system is suitable. The disadvantage of this is that an independently controllable sailing or rolling mode is not provided. In particular, neutral circuits or engine shutdowns are coupled to the specifications of the cruise control system or the brake control system. The possible uses of sailing or rolling mode are thus limited.

From WO 2003/037672 A1 a multi-step transmission, in particular for heavy commercial vehicles, is known, which is switched to a rolling mode upon detection of a low-consumption driving state in neutral. One low-consumption driving condition is then detected or the neutral position is switched when a target speed is predetermined and the driving speed would decrease without roll mode. This is assumed in particular when neither gas pedal nor brake pedal are actuated or equivalent variables change. For safety reasons, an additional braking device is available, which can be requested during the rolling operation. In addition, the currently engaged gear is taken into account. The disadvantage of this is that a forward-looking evaluation of the roll mode is rather not provided, whereby unfavorable neutral circuits can be triggered.

Against this background, the invention has for its object to provide a method that allows for a vehicle with an automatic or automated transmission consumption and low-emission driving with an efficient, comfortable and reliable sailing or rolling function.

The solution of this problem arises from the features of the main claim, while advantageous embodiments and further developments of the invention are the dependent claims can be removed.

The invention is based on the recognition that in a vehicle with an automatic or automated transmission unnecessary neutral circuits when using a rolling or sailing function while driving suppressed or appropriate situations for activating these functions can be reliably detected when relevant events or driving state changes continuously registered and are evaluated in a counter and, where appropriate, heavily fluctuating slope signals weighted in a counter are evaluated, and a current count is then used to enable or block the neutral circuits for the rolling or sailing mode. Accordingly, the invention is based on a method for controlling a rolling or sailing mode of a vehicle, with a drive train with a drive motor, an automatic or automated transmission and controllable switching means for interrupting the frictional connection in the drive train. To achieve the object, the invention provides that a power interruption is released when the count of a rolling or sailing mode counter falls below a predetermined first threshold or assumes the value zero, wherein the rolling or sailing mode counter in the presence at least an event stored in an event table is incremented, ie incremented, and otherwise decremented, ie counted down, or paused.

Under a roll mode, driving an open powertrain vehicle, i. an unpowered forward drive or fly useful drive, understood when the drive motor. A sailing mode is understood to mean the driving of a vehicle with an open drive train when the drive motor is switched off.

By the method according to the invention, the driving condition of the vehicle and the topography affecting the vehicle are correctly interpreted in such a way that unnecessary neutral circuits, i. Neutral circuits without saving effect or without activations of the rolling or sailing mode in unwanted for the driver or possibly safety-related situations can be reliably avoided.

The control measures can advantageously take place via a gearbox control unit which issues corresponding commands for initiating, executing or terminating a rolling or sailing operation. Such a control unit is for this purpose also with all the necessary sensors as well as necessary with other control devices, such as the engine control unit, connected to record the decision-relevant data or forward control commands. Basically, for vehicles with a speed of Control system and / or a brake control system no change of the software to the controllers for these systems required, which has a cost effect.

Thus, in the method, a counter is installed which is incremented by relevant events each by a certain amount, and which is decremented when there is no such event. The increments, that is to say the individual high-count amounts, can be specified differently for different events. It is possible that when acting over a certain period of time, the counter when detecting the event is incremented once, or that the counter from the detection of the event continuously in time clock of a timer of a control unit, preferably the transmission control unit, as long as it is incremented the event is active. The count is preferably limited to a predetermined maximum value.

The decrementing takes place advantageously in the clock cycle of the clock by one unit value per clock. If the count falls below a predetermined threshold or reached the value zero during decrement, a traction interruption in the drive train, such as a neutral circuit in the transmission of the vehicle, released. The traction interruption in the drive train can also be done by opening a starting clutch, it is irrelevant whether it is arranged separately in front of the transmission or part of the transmission.

On the other hand, if the counter reading exceeds a second predetermined threshold value when incrementing, or if the counter reading becomes greater than the value zero, then a neutral switching is not enabled.

This method of counting achieves a weighted, continuous evaluation of the current driving condition, which gives the transmission control unit a dis- Divorce criterion for an effective and reliable use of Rollbzw. Sailing function provides.

Events that increase the count to suppress neutral operation of the transmission or to open the starting clutch in an unfavorable situation for the driver in operation with the accelerator pedal pressed are stored in an event table. For example, the counter when operating the accelerator pedal, depending on the accelerator pedal angle and / or the deflection speed of the accelerator pedal or when pressing the brake pedal, be incremented depending on the brake pedal angle and / or the deflection speed of the brake pedal. Furthermore, the counter can be incremented with an activated engine brake and / or with an activated additional brake device, for example a hydrodynamic intarder. In these situations, neutral shifting would tend to counteract the driver's desire for greater or sustained acceleration or deceleration. Accordingly, with a currently detected acceleration or deceleration of the vehicle, in which a predetermined threshold value is exceeded, a neutral circuit does not make sense. Therefore, in this case, the count is increased.

Furthermore, the counter reading can be increased if a previously active cruise control system or brake control system is switched off. The deactivation of such a device indicates that a traffic situation has changed in such a way that a momentary activation of a rolling or sailing mode does not seem to make sense. It is possible that a braking process or a positive vehicle acceleration is imminent.

In addition, steering movements may be provided with exceeding a predetermined steering angle as an event parameter. If an existing sensor detects a relatively strong and / or frequent steering application, the vehicle is likely either in urban traffic or on a winding road, so at best very short-term Rolling or sailing phases would alternate with braking and acceleration phases in a short sequence, which also does not make sense.

The operation of a direction indicator can be used as another event parameter, since in this case a turn or lane changes is expected, with a rolling or sailing operation of the vehicle does not seem more appropriate.

The operation of a hazard warning system or a Hupanlage indicates a safety-relevant driving situation, for example, when approaching a jam end or a vehicle breakdown or other dangerous situation in which at least no automatic neutral circuit should take place. Therefore, the counter is also appropriately incremented in this case.

The aforementioned event parameters represent only a selection of criteria that can be taken into account in the counter function and are stored in the event table. The person skilled in the art will be able to supplement and modify the event table further.

The sailing or rolling mode can basically be activated if the current road gradient allows a drive-free forward drive or a fly-by-drive.

However, since the calculated or detected by a conventional sensor driving signals slope signals in practice can be very noisy and / or superimposed by disturbing vibrations, it is also advantageous that the practicability of an adhesion interruption of the drive train while driving with the help of an analysis of the road topography is evaluated on the basis of a continuously calculated and / or measured gradient, wherein a counter within a predefined gradient window, which is defined by a first limit value for a hill start and a second limit value for a downhill run, depending on the current The degree of slope is variably incremented or decremented and is set to an initial value outside of this grade window.

Thus, two thresholds are defined, representing one limit slope, one slope, the other slope. Within these limits, the counter can run. Below or above the thresholds, the counter reading is initialized to a starting value.

Depending on the current gradient signals, different increment values or decrement values are read into the counter, which increase or decrease the counter reading, so that the counter can be read at a speed for the scrolling signal. Sail mode predefined preferred grade of maximum expires quickly. Thus, deviate from this grade strong signal fluctuations lead to a delay or suspension of a neutral circuit, so that as a result, irregularities and inaccuracies in the slope signal affect the recognition of the preferred slope less.

In the transition from a slope to a steep slope, which is rather unsuitable for the rolling or sailing mode, since the braking effect of a coupled drive motor is possibly required, in the transitional period in which the gradient signal is in the range of the preferred slope, just run down the counter and trigger a neutral circuit. To such a falsely recognizing one for the Rollbzw. Sailing mode suitable to prevent topography can be further provided that in addition the gradient of the grade is evaluated, and that when exceeding a predetermined limit for positive gradients or falls below a predetermined limit for negative gradients, the counter is stopped.

To clarify the invention, the description is accompanied by a drawing of an embodiment. In this shows 1 shows a diagram for the course of the counter when carrying out a method according to the invention for enabling a rolling or sailing mode in the case of an accelerator pedal brake pedal actuation,

FIG. 2 shows a diagram with an alternative counter course in the case of accelerator pedal or brake pedal actuation, FIG.

Fig. 3 is a diagram for performing a rolling or sailing mode when driving with a transition to a steep slope, and

Fig. 4 is a diagram for performing a rolling or sailing mode when driving with a transition to a gentle slope.

The figures represent courses of relevant for the invention driving situations, as they can occur in a motor vehicle, such as a commercial vehicle, with an automatic transmission and a controllable via a transmission control neutral circuit for a rolling or sailing function.

An inventive method for controlling a rolling or sailing mode of such a vehicle is essentially based on the fact that a neutral circuit is enabled when the count of a rolling or sailing mode - counter falls below a predetermined first threshold or assumes the value zero, wherein the counter is incremented in the presence of at least one of stored in an event table events associated with the respective event values, and that a neutral circuit is suppressed when the count exceeds a second threshold or greater than zero.

Accordingly, according to the time diagram of FIG. 1, the vehicle is initially at a time t ₀ in a driving state in which no relevant event is active. Accordingly, the counter reading n = 0 and a neutral shift of the transmission or an opening of a starting clutch is released. ben. If the vehicle is traveling at a (negative) grade deemed suitable for the roll or sail mode at that time, a controller could trigger neutral.

At a time ti, a brake pedal actuation M _B stored in an event table takes place with a specific pedal deflection angle or an exceeding of this pedal deflection angle. The count n is incremented once, so that it is above the value zero. At a subsequent time t ₂ ends after a period .DELTA.ti the relevant brake pedal actuation M _B , after which the counter is decremented in time with the clocked control unit. At a subsequent time t ₃ after a period At ₂ , in which the count decreases as described, the driver operates according to the signal M _F an accelerator pedal with an event-relevant Pedalauslenkwinkel. The counter is therefore no longer counted down, but is again increased by a certain increment. At a time t ₄ , the accelerator pedal operation M _F ends after a period At ₃ , so that from this time t ₄ no relevant event is active. The count n is decremented from the next controller clock and reaches after a period At ₄ at a time t _5, a lower threshold n _nθU trai, in which a neutral circuit or an opening of the starting clutch is released.

FIG. 2 shows an alternative course of the counter, in which the counter, when an event is active, is not incremented by an event-dependent value by a single amount, but rather in the right cycle of the control unit, while the respective event is active. Accordingly, a brake pedal actuation M _B takes place again at a time ti, whereupon the counter value increases steadily in the period Δti, for example by two incremental units per 10 msec. So that the counter does not assume excessively high values when the brake pedal is pressed continuously, the counter reading n may be limited to a maximum value. In the following period At ₂ , no event is active, so the counter is decremented. At time t ₃ , the driver again actuates the accelerator pedal in event-relevant Wise. As a result, the count in the period At _{3 is} steadily increased, for example, by one increment unit per 10 msec. At time t ₄ ends as before the accelerator pedal operation and the counter begins to expire. Due to the additional time-dependent amount of incrementing of the counter, the release decision for a neutral shift or for opening the launch clutch includes a stronger weighting of the duration of a relevant event.

In Fig. 3, a scenario is shown, in which the vehicle travels a road that goes from an increase in a steep incline. The upper curve in the diagram shows a measured or calculated slope m = dy / dx, the middle curve an associated gradient m '= dy / dx ^{2 of} the slope m and the lower curve an associated meter reading course n (t).

After a first steady increase, the vehicle overcomes a hilltop and the slope is negative, ie goes into a downhill. For a transitional period Δtmroii, the slope is in a range Am ₁ - _ON , which is pre-determined since the slope level in the event table

Does not exceed or falls short of limit values, is approved as suitable for activation of the rolling or sailing function. Accordingly, the counter would now expire and at a time t _new trai the neutral circuit of the transmission or the opening of the starting clutch triggered. However, the gradient m 'of the slope m is already below a gradient gradient limit m'ι _im at this point, which indicates that a steep gradient begins, with a limit value violation included in the event table. The rolling or sailing mode should therefore be terminated after a short time. Consequently, the neutral circuit of the transmission or the opening of the starting clutch is not released, but the counter is stopped at a count n _fixed .

On the other hand, Fig. 4 shows a scenario in which the vehicle travels a road passing from a slope to a gentle slope in which the vehicle Vehicle over a relatively large period Δtmroii can go into the rolling or sailing mode. The count n is held constant for a short period AW, during which the slope changes its sign and the limit gradient is reached, to an initialization value. As soon as the gradient m and the gradient gradient m 'are within a permissible range, the count n is reduced and triggers the neutral circuit or the opening of the starting clutch at the _instant t _nθU trai. The rolling or sailing mode is thus released shortly after reaching the gentle gradient.

LIST OF REFERENCES

m slope

Δm _r0 ιι pitch range for roles

m 'gradient gradient

m ' _l i _m limit value of the gradient gradient n counter reading

ri _f i _x Holds count

n _new trai counter reading for neutral

M _B brake pedal operation

M _F accelerator pedal operation

t time

t | ... t ₅ time

Δ.1 ... Δ.4 period

Δt _mro ii Roll mode activation period

Δt _nt i _x time interval with counter reading stopped

Claims

claims

1. A method for controlling a rolling or sailing mode of a vehicle, with a drive train with a drive motor, an automatic or automated transmission and controllable switching means for interrupting the frictional connection in the drive train, characterized in that a frictional connection is released when the count (n ) of a roll mode counter falls below a predetermined first threshold value (n _nUUtra i) or assumes the value zero, wherein the roll mode counter is incremented and otherwise decremented or stopped in the presence of at least one event stored in an event table ,

2. The method according to claim 1, characterized in that a frictional interruption in the drive train is suppressed when the count exceeds a second threshold or greater than zero.

3. The method according to claim 1 or 2, characterized in that the release or suppression of the rolling or sailing mode is controlled by a transmission control unit.

4. The method according to any one of claims 1 to 3, characterized in that a frictional interruption in the drive train by a neutral circuit of the transmission or by opening a starting and shifting clutch takes place.

5. The method according to any one of claims 1 to 4, characterized in that in the event table at least several of the following events are stored:

- accelerator operation (M _F ), depending on the deflection angle, - accelerator operation (M _F ), depending on the deflection speed,

- brake pedal operation (M _B ), depending on the deflection angle,

- brake pedal operation (M _B ), depending on the deflection speed,

- engine brake operation,

- Intarder actuation,

- shutdown cruise control system,

- Shutdown brake control system,

- Steering movement, steering angle dependent

- direction indicator operation,

- warning system operation,

- vehicle acceleration, depending on size,

- vehicle deceleration, depending on size,

- ascent, depending on grade,

- Downhill, depending on the grade.

6. The method according to any one of claims 1 to 5, characterized in that the increments are each set variable depending on the event.

7. The method according to any one of claims 1 to 6, characterized in that in a continuous event, the counter is incremented when detecting the event once.

8. The method according to any one of claims 1 to 6, characterized in that in a continuous event, the counter from the detection of the event is continuously incremented clocked, and while the event is active, wherein the count is limited to a predetermined maximum value.

9. The method according to any one of claims 1 to 8, characterized in that the counter is clocked decremented.

10. The method according to any one of claims 1 to 9, characterized in that the practicability of an adhesion interruption of the drive train while driving by means of an analysis of the road topography on the basis of a continuously calculated and / or measured grade grade (m) is evaluated, wherein a counter within a predetermined slope degree window, which is bounded by a first limit for a Berganfahrt and a second limit for a downhill, depending on the current grade (m) is variably incremented or decremented, and is set outside the Gradient Level window to an initial value.

1 1. A method according to claim 10, characterized in that the counter is set at a downhill gradient depending on different speeds, so that it is decremented at a predetermined for the rolling or sailing mode preferred gradient with a maximum speed, and at a deviation is decremented or incremented more slowly by this grade of slope.

12. The method according to claim 10 or 1 1, characterized in that in addition the gradient (m ¹ ) of the gradient (m) is evaluated, and that when exceeding a predetermined limit value for positive gradients or falling below a predetermined limit (m'ι _im ) for negative gradients the counter is stopped.