DE102020119314A1 - Method for operating an automatic start-stop system in a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating an automatic start-stop system in a motor vehicle with an internal combustion engine, a manually operated transmission and a pedal-operated clutch, the internal combustion engine being automatically stopped or restarted under predetermined conditions. According to the invention, when the automatic start-stop system has automatically stopped the internal combustion engine while driving and the predetermined conditions for a restart are met, it is determined which gears are engaged without risk of damage to the transmission or parts thereof or other vehicle components can become; predicts whether and which gear a driver of the motor vehicle is trying to engage, and warns the driver if the gear he is trying to engage is not one of the gears determined to be suitable.

Description

The invention relates to a method for operating an automatic start-stop system in a motor vehicle with an internal combustion engine, a manually operated transmission and a pedal-operated clutch, the internal combustion engine being stopped or restarted automatically under predetermined conditions, and a motor vehicle with an automatic start-stop system according to the preambles of the independent claims.

Such a method is from DE 10 2013 219 108 A1 known, which also mentions the possibility that the internal combustion engine can also be stopped or restarted at higher speeds, e.g. B. up to vehicle speeds of around 12 km/h to maximize the time with the combustion engine stopped.

Automatic start-stop systems come in two varieties, one that allows the engine to be stopped and restarted only when the transmission is in neutral (SIN; Stop In Neutral), and one that allows the engine to be stopped and restarted when the transmission is in neutral Gear (SIG; Stop In Gear) enabled.

The first variant allows the engine to be switched off when the vehicle speed is close to 0 km/h, the transmission is in neutral and the clutch pedal is largely in the released position (near the top of its stroke). The engine restarts when the driver starts to use the clutch. A 12V starter is sufficient for a restart.

The applicant would like to introduce so-called Low Speed Stop in Gear (LSSG) in its 48V mild hybrid (mHEV) vehicles with manual transmission. This is a further development of the standard automatic start-stop system in vehicles with a manual transmission. Firstly, the engine can be switched off at slightly higher vehicle speeds, up to 25 km/h. Second, the engine can be turned off while a gear is still engaged as long as the clutch pedal is depressed and the brake applied. The engine may also be switched off when idling. However, restarting from neutral does not occur until both the clutch is stepped on and the transmission comes out of neutral (in either order). An integrated 48V belt starter generator (B-ISG) restarts the engine.

In order to be able to implement LSSG functionality in vehicles that have electrical components taken over from earlier models, the 12V system provided for this purpose must be able to be supplied from a 48V battery. This means that components carried over from earlier models, e.g. B. Power steering also work when the engine is not running. Also, models with electric brake boosters can maintain brake boosting when the engine is off. However, power steering and brake boosting are not essential for LSSG.

Another key component in such vehicles is the 48V-B-ISG. The B-ISG starts the engine faster than a conventional 12V starter. This is required for SIG (Stop In Gear) functionality as the driver expects to propel earlier than with (SIN; Stop In Neutral) functionality. This is due to the fact that the engine restart triggers occur later in time for SIG than for SIN.

LSSG systems have three selectable vehicle speed thresholds above which the engine may shut down: Low (15 km/h), Medium (20 km/h) and High (25 km/h). The applicant is also aiming for so-called HSSG (High Speed Stop in Gear) systems in which these threshold values are even higher, e.g. B. in the form of the following values: Low (15 km/h), Medium (50 km/h) and High (maximum vehicle speed). The factory default for both systems would be Low. To activate HSSG, the driver must go into the menu system of the vehicle's human-machine interface.

In particular, HSSG should be available for mHEV vehicles with power steering and brake boosters. If there is a fault with the power steering, brake booster or the 48V supply of the 12V system, HSSG will not be allowed.

It is not expected that many drivers will use HSSG in conjunction with SIG. This is because the driver can only coast the vehicle passively with the clutch and brake fully depressed to increase engine shut down times, which can be uncomfortable. Drivers will tend to prefer HSSG in conjunction with SIN.

So-called idle coasting, passive coasting with overrun cut-off and decoupled powertrain, goes a step further than the traditional method of coasting with only overrun cut-off. There is no engine drag, resulting in less vehicle deceleration, which can help save fuel.

In an automatic start-stop system that also works at higher speeds in a vehicle with a manually operated transmission, the engine shuts off automatically, possibly even at any vehicle speed, whether idling (SIN) or in gear (SIG), the problem arises that the vehicle speed may decrease or increase significantly during "coast" after the engine has been automatically shut off is.

It is possible to indicate the neutral position to the driver if there is a corresponding sensor (Gear Neutral Sensor; GNS) on the manual transmission.

However, the driver may not be aware of which gear to reselect when propulsion is required again, and may shift into an inappropriate gear for the vehicle's current speed when attempting to actively drive again. If the driver engages, or even attempts to engage, an inappropriate gear, this can cause wear or damage to the engine or transmission, as well as disrupting a smooth ride. It is also possible that the vehicle is in the wrong gear for the current vehicle speed when restarting, which can lead to clutch and/or engine damage.

In particular, a synchronizing mechanism is at risk if the driver attempts to engage a gear which is far too low for the vehicle speed by pressing and holding the gear selector. During this time, the synchro rings will suffer damage when attempting to accelerate other parts of the transmission, but the driver will not normally be able to tell that damage is occurring except from the force exerted by a locking ring that restricts the normal full travel of the gear selector (gear selector). prevented. In all situations, when a synchronizer mechanism wears excessively, the driver will have difficulty engaging the affected gear without being aware of the cause, leading to warranty claims and customer dissatisfaction.

The invention is based on the object of specifying a method for operating an automatic start-stop system that makes it possible to increase the speed up to which start-stop operation is possible, in particular up to the maximum vehicle speed without the Increase the risk that excessive wear or damage to the engine, clutch, gearbox or gearbox parts will occur during operation.

This object is achieved by a method and a motor vehicle with the features of the independent patent claims.

Advantageous developments of the invention are specified in the dependent patent claims.

According to the invention, it is constantly determined, or at least when the vehicle is rolling with the combustion engine stopped and the conditions for a restart are met, which gears can just be engaged without risk of damage to the transmission. In addition, a prediction is made as to whether and which gear a driver of the motor vehicle is currently attempting to engage. The driver is warned if the gear he is attempting to engage is not one of the gears determined to be suitable.

This makes it possible to have an automatic start-stop system work at vehicle speeds of up to 25 km/h, up to 50 km/h or even up to a maximum vehicle speed.

As is known, the conditions under which the internal combustion engine is automatically stopped or restarted include certain combinations of positions and changes in position of the selector lever, accelerator pedal and brake pedal. They can be different for SIN and SIG.

The prediction as to whether and which gear a driver of the motor vehicle is currently attempting to engage can be carried out using signals from a selected gear sensor, which has sensors for detecting all possible positions of a gear selection element.

Such a sensor is from DE 10 2012 209 515 A1 known. This teaches that the sensor can provide useful information about an intended gear shift, which should enable a vehicle control system to react more quickly to driver requests.

In addition to using the selected gear sensor for the gear prediction according to the invention, this can of course also be used to keep the driver up to date during a rolling phase without actuating the gear lever by means of a suitable display as to whether a gear just engaged still matches the current vehicle speed to minimize unnecessary warnings.

In an advantageous development of the invention, an attempt to engage a gear is recognized by this or is also recognized by this and the output of the warning is made dependent on the selector lever being in a specific shift gate and in synchronization tion area stops moving or for a longer period of time than is normal.

In an advantageous development of the invention, the determination of which gears can be engaged without risk of damage is carried out taking into account an estimate of the current uphill or downhill gradient of the surface on which the vehicle is driving.

In an alternative or additional advantageous development of the invention, it is determined which gears can just be engaged without risk of damage, taking into account a driving mode preset by the driver, which represents his preferred driving style.

Gear recommendation displays, which also take incline/downgrade/driving mode into account, are known per se, for example from DE 10 2011 121 476 A1 .

In particular, the determination of which gears can just be engaged without risk of damage may be performed using one or more look-up tables and/or in accordance with uphill/downhill/driving mode values.

In a motor vehicle with an internal combustion engine, a manually operated transmission, a pedal-operated clutch and an automatic start-stop system that automatically stops or restarts the internal combustion engine under predetermined conditions, the automatic start-stop system is set up according to the invention for vehicle speeds of up to at least 15 km/h to work. The motor vehicle also has a selected gear sensor and is set up to carry out a method as mentioned above.

• 1 ein typisches Aufenthaltsdiagramm eines Wählhebels, wie mit einem Gewählter-Gang-Sensor gewonnen;
• 2 einen Graphen eines zeitlichen Verlaufs der Wählhebelposition und Wählhebelgeschwindigkeit in Gangwahl-Richtung während eines Schaltens vom ersten in den zweiten Gang;
• 3 einen Graphen von minimalen und maximalen Geschwindigkeiten im ersten bzw. im zweiten Gang in Abhängigkeit von Steigung/Gefälle; und
• 4 einen Graphen von unterschiedlichen minimalen und maximalen Soll-Motordrehzahlen je nach Fahrmodus.

A description of exemplary embodiments follows with reference to the drawings. Show in it:

• 1 a typical location diagram of a selector lever as obtained with a selected gear sensor;
• 2 a graph of a time course of the selector lever position and selector lever speed in the gear selection direction during a shift from first to second gear;
• 3 a graph of minimum and maximum speeds in first and second gear as a function of incline/decline; and
• 4 a graph of different minimum and maximum target engine speeds depending on the driving mode.

A Selected Gear Sensor (SGS) is a transmission-mounted sensor that allows measurement of the position of the selector lever in both the X-axis and Y-axis directions of an "H-gate". These positions do not have to be measured directly or in an X-Y plane, but can be converted from PWM signals from two individual sensors that record the rotational and axial positions of a shift selector element within the transmission.

Normally, the position information obtained is used to determine which gear has been selected when gear selection is complete and the selector lever is in a fully engaged position (1,2,3,4,5,6,R). However, the continuous X-Y nature of the measurement also makes it possible to recognize or predict the gear that the driver is attempting to select without the gear already being engaged.

1 12 is a typical position diagram showing the positions of a number of position signals, converted to the shift gate level, which were obtained by means of the two individual sensors during a certain period of normal driving. Therein, the abscissa represents the position of the selector lever in the direction of shift gate selection, and the ordinate represents the position of the selector lever in the direction of any gear engagement.

When the driver attempts to shift between gears or from neutral into a gear, the position of the gear selector follows a well-defined vector determined by mechanical features and characteristics of the transmission. This means that it is possible to determine at a very early stage of the gear engagement attempt which shift gate the selector lever is controlling and thus also which synchronizer ring will be acted upon.

For a given vehicle speed, it can be continuously calculated which gears can be engaged at that speed without risk of damage to the engine, flywheel, clutch, gearbox or synchronizer elements. If, based on the position, speed and direction of movement of the gear selector, it appears that the driver is about to select an inappropriate gear, a warning is displayed to the driver that the gear is either too high or too low for the current vehicle speed.

The warning can be visual (e.g., a pop-up message on a screen), audible (e.g., a warning tone or a sound perhaps resembling grinding gears), or be given haptically (z. B. as a vibration provided with a corresponding actuator shift knob). As a result, the driver can quite intuitively grasp that he should select a different gear, if only because of the temporal relationship between the shift attempt and the warning. Expediently, however, the warning is issued to the driver with a short delay.

The warning can be limited to situations where it is likely that the driver is at serious risk of damaging a synchronizer mechanism. In 2 , which is a graph of a time course of selector lever position and selector lever speed in the gear selection direction during shifting from first to second gear, shows the XY position information or its change over time when the selector lever is in a specific shift gate and in which Area corresponding to the locking rings of the synchronizer mechanism no longer moves.

The continuous nature of the X-Y position measurement thus makes it possible to detect an attempt to force the selector lever into an inappropriate gear. This makes it possible to warn the driver in a timely and appropriate manner about the selection of an unsuitable gear, while minimizing unnecessary warnings. A reasonable balance of sensitivity can be achieved by using various calibratable thresholds, hysteresis ranges and timers.

In order to make the warning even more selective and effective, the determination of which gears can just be engaged without risk of damage can be carried out taking into account an estimate of the current uphill or downhill gradient of the surface on which the vehicle is traveling. Because on an uphill or downhill gradient, the appropriate gear may be smaller or larger than for a level road.

This can e.g. B. be performed using look-up tables that can be constructed on the basis of graphs, as in 3 shown as an example for minimum and maximum vehicle speeds in first and second gear as a function of incline/decline and vehicle speed.

In order to make the warning even more convenient for the driver, it is possible, alternatively or additionally, to determine which gears can currently be engaged without risk of damage, taking into account a driving mode preset by the driver, which represents his preferred driving style. Because depending on the driving style, the most suitable gear can be different, and the automatic start-stop system also receives information about how much propulsion should be provided with a restart.

This can e.g. B. be performed using a look-up table that can be constructed on the basis of a graph, as in 4 shown as an example for different minimum and maximum target engine speeds depending on the driving mode.

Instead of relying on one or more look-up tables, the determination of which gears can just be engaged without risk of damage can also be made by simply increasing/decreasing predetermined engine speed ranges in accordance with values for uphill or downhill or driving mode.

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• DE 102013219108 A1 [0002]
• DE 102012209515 A1 [0023]
• DE 102011121476 A1 [0028]

Claims (8)

A method for operating a start-stop system in a motor vehicle with an internal combustion engine, a manually operated transmission and a pedal-operated clutch, the internal combustion engine being stopped or restarted automatically under predetermined conditions, characterized in that when the start-stop system combustion engine has stopped automatically while driving and the predetermined conditions for a restart are met, the following steps are carried out: - determine which gears are currently suitable to be engaged without risk of damaging the gearbox or parts thereof or other vehicle components ; - to predict whether and which gear a driver of the motor vehicle is trying to engage, and - to warn the driver if the gear he is trying to engage is not one of the gears determined to be suitable. procedure after claim 1 , characterized in that this is carried out at vehicle speeds of up to 25 km/h, up to 50 km/h or up to a maximum speed of the vehicle. procedure after claim 1 or 2 , characterized in that the prediction as to whether and which gear a driver of the motor vehicle is trying to engage is carried out using signals from a selected gear sensor, which has sensors for detecting all possible positions of a gear selector element. Method according to one of the preceding claims, characterized in that an attempt to engage an unsuitable gear is recognized by this or is also recognized by this and the output of the warning is made dependent on the selector lever being in a specific shift gate and in a synchronization range not moving any more or for a longer period of time than would be normal. Method according to one of the preceding claims, characterized in that the determination of which gears are currently suitable for being engaged without risk of damage is carried out taking into account an estimate of the current uphill or downhill gradient of the surface on which the vehicle is driving. Method according to one of the preceding claims, characterized in that the determination of which gears are currently suitable for being engaged without risk of damage is carried out taking into account a driving mode preset by the driver, which represents his preferred driving style. procedure after claim 5 or 6 , characterized in that the determination of which gears are currently suitable to be engaged without risk of damage is carried out using one or more look-up tables and/or in accordance with uphill/downhill/driving mode values. Motor vehicle with an internal combustion engine, a manually operated transmission, a pedal-operated clutch and an automatic start-stop system that automatically stops or restarts the internal combustion engine under predetermined conditions, characterized in that the automatic start-stop system is set up for vehicle speeds of at least 15 km/h, that the motor vehicle has a selected gear sensor and that the motor vehicle is set up to carry out a method according to any one of the preceding claims.

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