KR102523848B1 - Method for controlling the coasting run of a vehicle with an automatic clutch - Google Patents

Abstract

The present invention relates to coasting of a vehicle with an automatic clutch, in which the clutch is opened to disengage the combustion engine from the power train while the gear is engaged to start the coasting run, and the clutch is engaged to end the coasting run. It relates to a method for controlling driving. In the method in which the coasting drive is automatically adjusted, the start or end of the coasting drive is automatically determined according to the driver's behavior.

Description

Method for controlling the coasting run of a vehicle with an automatic clutch

The present invention relates to coasting of a vehicle with an automatic clutch, in which the clutch is opened to disengage the combustion engine from the power train while the gear is engaged to start the coasting run, and the clutch is engaged to end the coasting run. It relates to a method for controlling driving.

A control method for a motor vehicle having an automatic clutch device, in which the vehicle is displaced by coasting, is known. Coasting can be understood as intentional disengagement in an overrun phase of a vehicle in which the accelerator pedal as a fuel supply allocation member is not operated. In this case, the vehicle rolls, but the engine driving the vehicle is switched off or operated at idle speed. In the coasting mode, the clutch is opened by the electronic control unit with the gear engaged, so that the vehicle rolls, but in this case no kinetic energy is lost due to the braking effect of the engine.

From DE 10 2013 219 345 A1 a method is known for controlling a drive unit of a motor vehicle with a driver assistance system, a coasting device and a regenerative device. In this case, depending on variables detected by the driver assistance system and characterizing the environment around the vehicle, and depending on the operating state of the vehicle power supply system, the sequence of the following driving states and/or the proportion over time of the driving state is determined. It becomes: Coasting - Regeneration - Braking - Coasting switch off. A disadvantage in this case is that the plurality of coasting processes are carried out continuously only for very short periods of time. However, this is perceived as objectionable by the driver.

Accordingly, an object of the present invention is to provide a method for controlling a coasting run of a vehicle, in which ride comfort is not impaired at all by the coasting processes.

According to the present invention, the above problem is solved by automatically determining the start and/or end of the coasting run according to the driver's action. The advantage of such a solution is that the driver's needs are taken into account because it is adapted to the current driving situation, so that the ride comfort is not adversely affected at all by the coasting run.

In a preferred manner, the end of the coasting run is made according to a preset braking action. However, since only specific braking operations lead to the end of the coasting drive, the duration of the coasting drive is maximized, and this situation leads to the minimization of vehicle fuel consumption. Thus, the vehicle can roll for a longer time because the speed is not reduced by the powertrain.

In one embodiment, the preset braking action is made as emergency braking. Due to this, the coasting of the vehicle is stopped only in dangerous situations.

In one alternative, when the brake cylinder pressure falls below a preset pressure threshold, a preset braking operation is performed. The undershoot of the pressure threshold means a dangerous situation that can occur in the vehicle. Repetitive braking operations with the combustion engine switched off can lead to a situation where the brake cylinder pressure becomes increasingly lower. As such, in this case, the end of coasting is realized immediately, so that the vehicle can be further decelerated by the powertrain or the brake cylinder pressure can be charged.

In a preferred manner, a preset braking operation is performed when the total duration of all braking operations with the combustion engine switched off exceeds a preset duration.

In one embodiment, the current driving situation of the vehicle is determined by the driving operation, in which case the vehicle is driving a curve and the start of the coasting drive is prevented when the current curvature of the curve exceeds a specific curvature threshold. . Thus, coasting is not permitted on narrow and/or steep curves.

In one modification, the current driving condition of the vehicle is determined by the vehicle acceleration, and in this case, when the current vehicle acceleration is less than the first acceleration threshold, the coasting drive is initiated, while the current vehicle acceleration is determined by the second acceleration threshold. When the acceleration threshold is exceeded, the coasting run is terminated. Therefore, the coasting run is executed only when the vehicle acceleration is optimal and when the driving operation is suitable, in order to continuously ensure ride comfort or driving safety.

In one embodiment, the current vehicle acceleration of the vehicle is determined from one or more wheel rotational speeds, in which case coasting is inhibited in uphill driving and/or downhill driving of the vehicle according to the vehicle acceleration determined from the wheel rotational speeds. If the negative vehicle acceleration is too high, initiation of the coasting run, especially by switching off the combustion engine, is inefficient and undesirable, since the vehicle must quickly accelerate again to go to normal driving operation. Conversely, if the positive vehicle acceleration is too high, coasting is inhibited to prevent a dangerous situation. Therefore, it is ensured that no coasting run can be set on a steeply descending road or on a steeply ascending road. By detecting the vehicle acceleration using wheel rotational speed, a separate acceleration sensor can be omitted, which simplifies implementation of the method and reduces cost.

In one embodiment, driver behavior is determined online. By observing driver behavior, coasting is permitted only when traffic conditions are suitable. With this online assessment, the driver's reaction is adapted to the driving or traffic situation within the coasting profile. In this case, in particular when and how often the driver has deviated from the coasting run is taken into account. In this embodiment, the storage of the driver profile can be omitted.

In one particularly simple embodiment, driver behavior in past periods is evaluated.

In order to realize the fastest possible adaptation of the coasting run, the driver's behavior is combined with the personalized driver profile. In this case, if the vehicle is notified of the stored driver profile, such as which driver initiated the driving action, the coasting action can advantageously be adapted to different vehicle drivers.

The present invention allows for a number of embodiments. Some of these embodiments will be described in more detail with reference to the figures shown in the drawing.

1 shows an embodiment for ending a coasting process during a braking operation process;
Figure 2 shows an embodiment of the coasting process when the acceleration is preset,
Figure 3 shows an embodiment for a coasting procedure when traffic conditions are suitable.

In today's vehicles, when a gear is engaged, an automatic opening of the clutch is carried out, in particular during driving of the vehicle, a situation such as this is referred to as coasting. In this case, an additional option exists in which the combustion engine is switched off during the coasting phase. The purpose of coasting is to disengage the combustion engine from the power train in order to avoid the drag torque of the power train as lost torque, a situation like this leading to fuel economy.

In each figure, various embodiments are shown for optimizing the automatic initiation or automatic termination of a coasting process, in which case the coasting process is made very efficient during the driving operation of the vehicle.

1 shows an embodiment for ending the coasting process during braking. In this case, Figure 1a shows the vehicle speed v over time t. In this case, curve A shows the light braking process during the coasting process, while curve B shows the braking process when the power train is engaged. In this case, the coasting process is only interrupted by a preset braking action, for example in an emergency braking situation or in the presence of a low brake cylinder pressure, since when the power train is engaged, during the coasting process This is because the vehicle speed is reduced more strongly than in the case of light braking of . By means of light braking during this coasting process, the duration of the coasting process is maximized and, at the same time, the fuel consumption is minimized. A mere slight decrease in vehicle speed v, clearly shown in curve A, allows the vehicle to roll over for a longer stretch.

In FIG. 1 b , fuel consumption KV is plotted over time t, in which case curve C shows the fuel consumption at idle of the combustion engine, while no fuel consumption occurs when the combustion engine is switched off. and this situation occurs during coasting, for example. Compared to using the vehicle without switching off the coasting, no fuel consumption is achieved when the coasting run is activated during the braking process.

2 shows an embodiment of the method according to the invention, in which the coasting process only takes place when the acceleration of the vehicle is optimal. In this figure, the height profile HP is shown over the distance s. In this case, the rectangle marked D indicates the area where coasting is prohibited in principle. These zones are steep downhill roads with steep rises in the road. In order to avoid coasting in these areas, coasting is only started or ended according to the optimal vehicle acceleration. In other words, coasting is permitted only in those areas of the road where there is a slight change in the height profile. For this purpose, the height profile HP is determined according to the vehicle acceleration. If the vehicle acceleration exceeds the first acceleration threshold, it is assumed that the vehicle is on a steeply descending road section, whereby an unacceptable acceleration of the vehicle occurs. As such, coasting is allowed only if the first preset acceleration threshold is not met. If the vehicle is driving up a steep hill, coasting is permitted only if the vehicle is in a section with an acceleration exceeding the second acceleration threshold. In areas where the second acceleration threshold is not met, it is assumed that the vehicle slows down during ascent due to the set coasting profile, so that it does not reach the hill under its own power. In this case, the acceleration values are determined in particular through the rotational speed of the wheels of the vehicle. Due to this configuration, the start or end of the coasting process is adjusted with reference to the driver's needs.

Figure 3 shows another embodiment of the method according to the invention, in which coasting is permitted only in suitable traffic conditions. In order to detect a suitable traffic situation, the driving situation is identified and evaluated online by the driver behavior, in this case from the evaluated driver behavior the coasting profile is adapted to the traffic situation. In the case of online identification of driver behavior, among other things, how often the driver deviated from the coasting process is identified. In Figure 3a, vehicle speed v is plotted over time t. Since there is a uniform vehicle speed v in this figure, the coasting strategy can simply be adapted to driver behavior.

Similarly in FIG. 3B , the vehicle speed v is shown over time t, and in this case, the vehicle speed undergoes a very large fluctuation. In the area E lying in front of the rectangle F, the vehicle attempts to coast. The course of coasting in this area is extremely short, and such conditions reflect current traffic conditions and/or driver needs. In order to be able to adjust the coasting process accordingly, the driver's behavior is observed for a preset period of x seconds.

Due to the frequent interruption of the coasting process for short periods, no coasting process is permitted in the area indicated by rectangle F. Only after exiting the rectangle F, the coasting process is allowed to start in the region G, where the vehicle speed is again approximately constant, since the driver's behavior during the past y seconds exhibited an approximately uniform profile.

Claims (10)

Controlling a coasting run of a vehicle having an automatic clutch, wherein the clutch is opened to disengage the combustion engine from the power train while the gear is engaged to start the coasting run, and the clutch is engaged to end the coasting run. In the method for
The start or end of coasting is automatically determined according to the driver's behavior,
The end of the coasting run is made according to a preset braking operation,
characterized in that the preset braking operation is performed when the brake cylinder pressure falls below the preset pressure threshold or when the total duration of all braking operations exceeds the preset duration with the combustion engine switched off. , A method for controlling a coasting run of a vehicle having an automatic clutch. delete delete delete 2. The method of claim 1, characterized in that the vehicle's current driving situation is determined by a driving operation, and when the vehicle travels on a curve and the current curvature of the curve exceeds a specific curvature threshold value, the start of the coasting drive is inhibited. A method for controlling a coasting run of a vehicle having an automatic clutch. The method according to claim 1 or 5, wherein the driving condition of the vehicle is determined by the vehicle acceleration, and when the current vehicle acceleration is less than the first acceleration threshold, the coasting drive is started, while the current vehicle acceleration is A method for controlling a coasting run of a vehicle having an automatic clutch, characterized in that the coasting run is terminated when the second acceleration threshold is exceeded. 7. The method of claim 6 , wherein the current vehicle acceleration of the vehicle is determined from the rotational speed of one or more wheels, and coasting is inhibited in uphill driving and/or downhill driving of the vehicle according to the vehicle acceleration determined from the rotational speed of the wheels. , A method for controlling a coasting run of a vehicle having an automatic clutch. 2. A method according to claim 1, characterized in that driver actions are determined online. 9. Method according to claim 1 or 8, characterized in that driver behavior in a past period is evaluated. 9. A method according to claim 8, characterized in that driver actions are combined with personalized driver profiles.

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