DE102009033866A1 - Method for operating a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a motor vehicle with a hybrid drive, in which a choice is made between a plurality of driving modes (70, 72, 74), a normal operating state (70) being selected in the presence of a drive torque request, in which a gear in a transmission (19) is engaged, a clutch (12) is closed and a drive torque is provided by the internal combustion engine (14), and if there is no drive torque request, a rolling mode (72) is selected in which a neutral gear is engaged in the transmission (19), the clutch (12) is closed and the internal combustion engine (14) is in an idling state, a second rolling mode (74) in which a gear is engaged in the transmission (19) is selected when there is a drive torque requirement below a predetermined threshold value, the clutch (12) is opened, a drive torque is provided by an electric motor (15) is and the internal combustion engine (14) is in the idle state.

Description

The The invention relates to a method for operating a motor vehicle according to the preamble of claim 1.

Such a method is from the WO 01/92049 A1 known. In such a method, when operating a motor vehicle, a plurality of driving modes are selected. In a normal operating state, which is selected in the presence of a drive torque request, a gear is engaged in a transmission and a clutch of the drive train of the motor vehicle is closed, wherein a drive torque is provided by an internal combustion engine of the motor vehicle. If there is no drive torque request, an input signal of a control unit for the transmission thus represents a neutral state of the accelerator pedal, where is changed to a rolling operation state in which a neutral gear is engaged in the transmission, the clutch remains closed and the engine is therefore decoupled from the wheels of the motor vehicle and remains in an idle state.

Of the So cars can, for example, on a slight slope or when rolling on a level track, your own kinetic and / or use potential energy to sustain driving, without dragging the engine to a loss of speed to lead.

Unfortunately, must even in the presence of minimum torque requirements of the rolling state be left and returned to the normal operating state become. This leads just in case of frequent, weak Slope changes of a roadway to waste energy. The Procedure continues to be limited to conventional, powered by internal combustion engines motor vehicles and uses additional Potentials of hybrid drives are not enough.

Of the Invention is therefore the object of a method according to the Preamble of claim 1 further develop so that the Fuel economy is improved and the use for hybrid vehicles is optimized.

This object is achieved by a method having the features of patent claim 1.
a neutral gear in the transmission ( 19 ) is engaged, the clutch ( 12 ) is closed and the internal combustion engine ( 14 ) is in an idle state

Next the already known driving modes, namely a Normal operating state in which a gear engaged in a transmission is, a clutch is closed and a drive torque of one Engine of the motor vehicle is provided and a first rolling operation state in which a drive connection between the internal combustion engine and a transmission output shaft is interrupted, is according to the invention in such a method second rolling operation state provided. This second rolling state becomes below a given drive torque request predetermined threshold value is selected and in particular For use in vehicles with parallel hybrid drive, in which an electric motor is arranged on the transmission input suitable.

in the first rolling operation state, the drive connection between the internal combustion engine and the transmission output shaft in particular be interrupted by a neutral gear engaged in the transmission is, the clutch is closed and the internal combustion engine in an idle state or shut down. But it is also possible that the said drive connection by opening the clutch is interrupted.

in the second rolling state a gear is engaged in the transmission, opened the clutch and arranged a drive torque from the transmission input Electric motor provided. By opening the clutch the internal combustion engine is decoupled from the transmission, so that no Drag torques of the internal combustion engine must be overcome. The internal combustion engine can then in particular in the idle state are located. But it is also possible that in the second rolling state the Internal combustion engine is stopped or stopped and only on request is restarted. By providing the drive torque from the electric motor comes with small and / or short-term torque requirements the savings potential of the hybrid drive fully to fruition, as such small torque requirements exclusively from the electric motor can be operated. It can be both acceleration and as well as brake requirements. There is no torque request more, so can immediately return to the first rolling state be returned, in which by inserting the neutral gear in the transmission the drive train is completely interrupted. exceeds the torque request the threshold value of the second rolling state, so an engine speed is synchronized and returned to normal operating condition in which, as usual, the drive torque of the Internal combustion engine is provided.

Particularly large savings in fuel and energy can be achieved through predictive control and selection of driving modes. For this purpose, environmental data, in particular Stei tion data of a roadway for an upcoming stretch of road, and / or operating state data such as speed, engine speed and the like evaluated and anticipated an expected value for the drive torque demand determined. On the basis of this expected value, a driving mode can then be selected subsequently. Incline data for a roadway can be determined, for example, based on a map and a vehicle position determined, for example, by means of GPS, or can also be determined by evaluating a constantly updated image of the roadway in front of the vehicle with a digital camera.

in the Following is the invention and its embodiments will be explained in more detail with reference to the drawings. Hereby show:

1 1 is a schematic representation of a powertrain for a hybrid motor vehicle for use with a variant of a method according to the invention;

2 a schematic representation of the components by means of which a variant of the method according to the invention is executable,

3 a flowchart of the choices of driving modes in the variant of the method according to the invention

4 and 5 schematic representations of roadway profiles, associated drive torques and selected driving modes for two exemplary driving situations.

According to 1 has a drive train 10 a motor vehicle, not shown, a prime mover 14 on which of a control device 16 is controlled. About a power actuator in the form of an accelerator pedal 52 For example, a vehicle operator can set the output torque of the prime mover 14 to adjust. On the transmission input shaft 11 is still an electric motor 15 arranged for the hybrid operation of the motor vehicle.

The coupling 12 and the gear shift transmission 19 are also from the controller 16 driven. The control device 16 stands in signal communication with actuators and sensors of the clutch, not shown 12 and the transmission 19 , Thus, the control device 16 the coupling 12 open or close and gear changes in the transmission 19 carry out. The control device 16 is also equipped with a shift lever 51 connected, by means of which the driver of the transmission 19 can request. Alternatively, circuits from a source to a target gear may also be used in a manner known per se by the controller 16 to be triggered. The determination of the target gear is among other things of the speed of the motor vehicle and an operating level of the accelerator pedal 52 dependent on the driver.

The gear 19 is designed as a so-called two-group transmission. Rotationally connected to the transmission input shaft 11 is a primary gearbox in the form of a splitter group 17 arranged. The split group 17 downstream is a main gearbox 18 , The main gearbox 18 is designed as an unsynchronized gearbox. It therefore has no synchronization for the individual gears. The synchronization of the speeds in a gear change is by means of the prime mover 14 carried out.

By means of the split group 17 can the transmission input shaft 11 over two different gear pairings 20 . 21 with a parallel to the transmission input shaft 11 arranged countershaft 22 be brought into operative connection. The gear pairings 20 . 21 have a different translation. The split group 17 is unlike the main gearbox 18 synchronized running.

On the countershaft 22 are rotationally fixed wheels 23 . 24 . 25 for the 3rd, 2nd and 1st gear of the main gearbox 18 arranged. The fixed wheels 23 . 24 . 25 comb each with associated loose wheels 26 . 27 . 28 which is rotatable on a coaxial with the transmission input shaft 11 arranged transmission output shaft 29 are arranged. The idler wheel 26 can by means of a sliding sleeve 30 , the loose wheels 27 and 28 by means of a sliding sleeve 31 rotationally and positively with the transmission output shaft 29 get connected.

A sliding sleeve 41 the split group 17 and the sliding sleeves 30 . 31 . 39 of the main gearbox 18 are with the actuators, not shown, of the transmission 19 actuated. This can be a positive connection between associated switching elements and the transmission output shaft 29 be prepared or interrupted.

From the transmission output shaft 29 becomes the converted torque and the speed of the prime mover 14 by means of a drive shaft 32 to a axle drive 33 transmitted, which in a conventional manner, the speed in equal or different proportions via two output shafts 34 . 35 to drive wheels 36 . 37 transfers.

The control device 16 is in signal communication with a lane information device in the form of a digital camera 53 , Which detects a portion of the road in the direction of travel of the motor vehicle. The camera 53 determines from this information about the course of the road, such as a slope or a slope, curves or a road condition such as moisture or ice. This information represents the camera 53 the control device 16 available, which these in the control of the prime mover 14 and the transmission 19 considered.

The Transmission can also have a so-called rear group which is arranged behind the main transmission. With this rearrangement group, which is executed as a range group can be, the number of gears of the transmission can be doubled again become. The transmission can also have a central Synchronizing element, such as via a transmission brake, feature. By means of the synchronizing element can be at upshifts For example, the countershaft to be braked.

The block diagram in 2 illustrates again the interaction of various components of the powertrain. A control unit 60 receives from a lookahead module 62 Information about the upcoming route, especially the slope of a roadway in front of the vehicle. From a control unit 64 the battery for the e-machine 15 will continue to provide information about the state of charge of the battery to the control unit 60 passed. Based on the received data, the control unit calculates 60 an expected value for torque requests along the line ahead of the vehicle. Based on this expectation, the control unit gives 60 then instructions to the controller 66 for the electric machine 15 in the form of a desired torque of the electric motor 15 and to a transmission control unit 68 in the form of a driving mode.

How out 3 can be seen, it can be selected between three driving modes. In normal operation 70 In this case, required drive torques in the usual way from the internal combustion engine 14 provided. The coupling 12 is closed and in gear 19 a gear is engaged. The electric motor 15 is not energized here and does not contribute to the drive torque. As soon as there is no torque request, it is in a first rolling operation state 72 passed over (transition 1). The coupling 12 is closed here, in gear 19 a neutral gear is engaged. Neither the electric motor 15 still the internal combustion engine 14 Contribute to the drive torque, the vehicle thus rolls completely unpowered, so that no additional energy is consumed. Represents the controller 60 determines that a high drive torque is desired again, for example, in an imminent strong slope, so again in the normal operating state 70 returned (transition 2b).

Expects the control unit 60 a drive torque below a predetermined threshold, for example, an imminent slight and short slope or even an imminent light and short slope, which requires a braking torque, so is in a second roll state 74 (Extended Ecoroll) (transition 3a). The coupling 12 is open in this state, leaving the internal combustion engine 14 from the drive train 10 is decoupled and runs in idle mode, with no drag torque is transmitted to the drive train. In the transmission 19 a gear is engaged, the electric motor 15 provides a drive torque. Thus, short and small torque requirements are bridged, without that of pure rolling in the operating state 72 on an activation of the internal combustion engine 14 must be resorted to.

If the short-term torque request ends, it can return to the pure roll state 72 be returned (transition 3a). For strong torque requests during the second rolling state 74 can also be immediately in the normal operating state 70 be passed, in which the internal combustion engine 14 again provides the desired moments (transition 3b).

The first rolling state 72 This represents the most fuel-efficient operating mode of the vehicle, since the drag losses in the transmission with engaged neutral gear and closed clutch are lower than in the second rolling operation state 74 in which a gear is engaged and the clutch is open. The second operating state 74 thus serves exclusively the operation of short-term and low torque requirements.

This is exemplary in the 4 and 5 shown. The curve 76 in 4 shows a roadway profile Fb over the path s. In a first level area 78 the road becomes the vehicle 80 operated with a high drive torque M_an, as in the curve 82 to recognize. As in the diagram 84 are shown in this area, the rolling states 72 and 74 inactive, the vehicle 80 is in normal driving condition 70 , In one to the level 78 subsequent gradient 86 is the vehicle 80 in pure rolling mode, the drive torque here is zero. After the slope 68 the road has a flattening area 88 in which there is a non-zero torque request, as in the range 90 the momentum curve 82 to recognize. The drive torque requirement is in the range 90 below a predetermined threshold, leaving the vehicle 80 not in the normal operating state 70 but rather the second roll mode 74 occupies. In a subsequent area 92 the roadway at which the slope increases again, the torque requirement exceeds this threshold, so that again in the normal operating state 70 is returned.

5 shows an alternative situation. To a level 94 in the roadway profile 96 closes a slope 98 in which, as already on the basis of 4 described the vehicle 80 from the normal operating state to the free rolling state 92 passes. When flattening the slope in the area 100 First, a positive drive torque is required, which is in the range 102 the torque curve is below the threshold for the normal operating condition. The vehicle 80 So here goes into the second Rollbetriebszustand 74 about, in which the torque requirement by the electric motor 15 is covered. Following the flattening 100 is the roadway profile 96 in a stronger gradient 104 above. As in the area 106 To recognize the momentum curve, there is a need for a negative drive torque, so for a deceleration of the vehicle 80 , Also, the negative drive torque is below a predetermined threshold, so that again only the electric motor 15 in the second rolling state 70 is used. In contrast to the area 102 the momentum curve becomes the electric motor here 15 not to accelerate, but to slow down the vehicle 80 used. The recuperated energy can in turn be supplied to the battery of the electric part of the hybrid drive, which leads to additional energy savings.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 01/92049 A1 [0002]

Claims (4)

Method for operating a motor vehicle with a hybrid drive, in which a plurality of driving modes ( 70 . 72 . 74 ) is selected, wherein in the presence of a drive torque request a normal operating state ( 70 ), in which a gear in a transmission ( 19 ), a coupling ( 12 ) is closed and a drive torque from the internal combustion engine ( 14 ), and in the absence of a drive torque request, a first rolling operation state ( 72 ), in which a drive connection between the internal combustion engine ( 14 ) and a transmission output shaft ( 29 ) is interrupted, characterized in that in the presence of a drive torque request below a predetermined threshold value, a second rolling operation state ( 74 ), in which a gear in the transmission ( 19 ) is engaged, the clutch ( 12 ), a drive torque from an electric motor ( 15 ) provided. Method according to Claim 1, characterized in that when the threshold value is exceeded in the second rolling operation state ( 74 ) an engine speed is synchronized and in the normal operating state ( 70 ) is changed. Method according to claim 1 or 2, characterized in that by a control device ( 60 ) Ambient data, in particular slope data of a road, for an upcoming stretch of road, and / or operating condition data, in particular travel speed, engine speed and the like., Are evaluated and anticipated an expected value for a drive torque demand is determined. Method according to Claim 4, characterized in that, based on the expected value, a driving mode ( 70 . 72 . 74 ) is selected.

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