Method for a serial driving mode of a motor vehicle

Abstract

A method for serial operation of a motor vehicle with a transmission having a first electric machine, which is operated as a motor for driving the motor vehicle, and a second electric machine, which is operated as a generator, includes, after a generation of a change-over signal, switching the first electric machine from the operation as a motor to the operation as a generator, and switching the second electric machine from the operation as a generator to the operation as a motor in order to drive the motor vehicle.

Claims

1. A method for serial operation of a motor vehicle (1) that includes a transmission (2), comprising: operating a first electric machine (3) of the transmission (2) as a motor for driving the motor vehicle (1); operating a second electric machine (4) of the transmission (2) as a generator; generating a change-over signal when a temperature of the first electric machine (3) exceeds a threshold value or when the temperature of the first electric machine (3) exceeds the threshold value and a temperature of the second electric machine (4) falls below another threshold value; and after generation of the change-over signal, switching the first electric machine (3) from the operation as the motor to the operation as the generator, and switching the second electric machine (4) from the operation as the generator to the operation as the motor in order to drive the motor vehicle (1).

2. The method of claim 1, wherein: the first electric machine (3) is switched from the operation as the motor to the operation as the generator without an interruption of tractive force; and/or the second electric machine (4) is switched from the operation as the generator to the operation as the motor without the interruption of tractive force.

3. The method of claim 1, further comprising charging an electric accumulator with the first electric machine (3) operating as the generator or with the second electric machine (4) operating as the generator, wherein either the first electric machine (3) is operated as the motor and the second electric machine (4) is operated as the generator or the first electric machine (3) is operated as the generator and the second electric machine (4) is operated as the motor.

4. A transmission, configured to implement the method of claim 1.

5. A method for serial operation of a motor vehicle (1) that includes a transmission (2), comprising: operating a first electric machine (3) of the transmission (2) as a motor for driving the motor vehicle (1); operating a second electric machine (4) of the transmission (2) as a generator; generating a change-over signal when a difference between a temperature of the first electric machine (3) and a temperature of the second electric machine (4) exceeds a threshold value; and after generation of the change-over signal, switching the first electric machine (3) from the operation as the motor to the operation as the generator, and switching the second electric machine (4) from the operation as the generator to the operation as the motor in order to drive the motor vehicle (1).

6. A transmission, configured to implement the method of claim 5.

7. A method for serial operation of a motor vehicle (1) that includes a transmission (2), comprising: operating a first electric machine (3) of the transmission (2) as a motor for driving the motor vehicle (1); operating a second electric machine (4) of the transmission (2) as a generator; and after generation of a change-over signal, switching the first electric machine (3) from the operation as the motor to the operation as the generator, and switching the second electric machine (4) from the operation as the generator to the operation as the motor in order to drive the motor vehicle (1), the switching of the second electric machine (4) from the operation as the generator to the operation as the motor comprises in the following sequence carrying out a load reduction at an internal combustion engine (VM) and the second electric machine (4) in order to unload a first clutch (K2) of the transmission (2), disengaging the first clutch (K2), synchronizing a first shift element (B) of the transmission (2), engaging the first shift element (B) to form a driving connection between the second electric machine (4) and an axle differential (18), carrying out a load reduction at the first electric machine (3) and a load build-up at the second electric machine (4) in order to unload a second shift element (A) of the transmission (2), disengaging the second shift element (A), synchronizing a second clutch (K1), engaging the second clutch (K1) to form a driving connection between the internal combustion engine (VM) and the first electric machine (3), and carrying out a load build-up at the internal combustion engine (VM) and the first electric machine (3) such that the first electric machine (3) is operated as the generator.

8. The method of claim 7, wherein: the first electric machine (3) is drivingly connectable to the internal combustion engine (VM) with the second clutch (K1); and/or the second electric machine (4) is drivingly connectable to the internal combustion engine (VM) with the first clutch (K2).

9. The method of claim 7, wherein: a second gear is implemented by engaging the first shift element (B); and/or a first gear is implemented by engaging the second shift element (A).

10. The method of claim 7, wherein: the synchronization of the second shift element (A) is carried out with a closed-loop control of a rotational speed of the first electric machine (3); and/or the synchronization of the first shift element (B) is carried out with a closed-loop control of a rotational speed of the second electric machine (4).

11. A transmission, configured to implement the method of claim 7.

12. A method for serial operation of a motor vehicle (1) that includes a transmission (2), comprising: operating a first electric machine (3) of the transmission (2) as a motor for driving the motor vehicle (1); operating a second electric machine (4) of the transmission (2) as a generator; after generation of a change-over signal, switching the first electric machine (3) from the operation as the motor to the operation as the generator, and switching the second electric machine (4) from the operation as the generator to the operation as the motor in order to drive the motor vehicle (1); generating a further change-over signal when a temperature of the second electric machine (4) exceeds a threshold value or when the temperature of the second electric machine (4) exceeds the threshold value, and a temperature of the first electric machine (3) falls below another threshold value; after generation of the further change-over signal, operating the first electric machine (3) as the motor, and operating the second electric machine (4) as the generator.

13. A method for serial operation of a motor vehicle (1) that includes a transmission (2), comprising: operating a first electric machine (3) of the transmission (2) as a motor for driving the motor vehicle (1); operating a second electric machine (4) of the transmission (2) as a generator; after generation of a change-over signal, switching the first electric machine (3) from the operation as the motor to the operation as the generator, and switching the second electric machine (4) from the operation as the generator to the operation as the motor in order to drive the motor vehicle (1); generating a further change-over signal when a difference between a temperature of the second electric machine (4) and a temperature of the first electric machine (3) exceeds a further threshold value; and after generation of the further change-over signal, operating the first electric machine (3) as the motor, and operating the second electric machine (4) as the generator.

14. A method for serial operation of a motor vehicle (1) that includes a transmission (2), comprising: operating a first electric machine (3) of the transmission (2) as a motor for driving the motor vehicle (1); operating a second electric machine (4) of the transmission (2) as a generator; and after generation of a change-over signal, switching the first electric machine (3) from the operation as the motor to the operation as the generator, and switching the second electric machine (4) from the operation as the generator to the operation as the motor in order to drive the motor vehicle (1); and after generation of a further change-over signal, operating the first electric machine (3) as the motor, and operating the second electric machine (4) as the generator, switching the first electric machine (3) from the operation as the generator to the operation as the motor comprises in the following sequence: carrying out a load reduction at an internal combustion engine (VM) and the first electric machine (3) in order to unload a second clutch (K1) of the transmission (2), disengaging the second clutch (K1), synchronizing a second shift element (A) of the transmission (2), engaging the second shift element (A) to form a driving connection between the first electric machine (3) and an axle differential (18), carrying out a load reduction at the second electric machine (4) and a load build-up at the first electric machine (3) in order to unload a first shift element (B) of the transmission (2), disengaging the first shift element (B), synchronizing a first clutch (K2), engaging the first clutch (K2) to form a driving connection between the internal combustion engine (VM) and the second electric machine (4), and carrying out a load build-up at the internal combustion engine (VM) and the second electric machine (4) such that the second electric machine (4) is operated as the generator.

15. The method of claim 14, wherein: the internal combustion engine (VM) idles between synchronizing the second shift element (A) and engaging the first clutch (K2); and/or the first electric machine (3) is supplied with electrical energy from an electric accumulator when the first electric machine (3) is operated as the motor, and the second electric machine (4) is supplied with electrical energy from the electric accumulator when the second electric machine (4) is operated as the motor.

16. The method of claim 14, wherein: the first electric machine (3) is drivingly connectable to the internal combustion engine (VM) with the second clutch (K1); and/or the second electric machine (4) is drivingly connectable to the internal combustion engine (VM) with the first clutch (K2).

17. The method of claim 14, wherein: a second gear is implemented by engaging the first shift element (B); and/or a first gear is implemented by engaging the second shift element (A).

18. The method of claim 14, wherein: the synchronization of the second shift element (A) is carried out with a closed-loop control of a rotational speed of the first electric machine (3); and/or the synchronization of the first shift element (B) is carried out with a closed-loop control of a rotational speed of the second electric machine (4).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject of example aspects of the invention is schematically represented in the FIGURE and is described in the following. Wherein:

(2) FIG. 1 shows a representation of a transmission, in the case of which the method according to example aspects of the invention can be carried out.

DETAILED DESCRIPTION

(3) Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

(4) The transmission 2 shown in FIG. 1 is installed in a motor vehicle 1 (not shown in greater detail in FIG. 1). The transmission 2 includes a motor vehicle drive unit, such as an internal combustion engine VM, a first electric machine 3, and a second electric machine 4. In addition, the transmission 2 includes a first sub-transmission TG1 and a second sub-transmission TG2. Each of the two sub-transmissions has two gear planes. The first sub-transmission TG1 is always drivingly connected to the first electric machine 3 and the second sub-transmission TG2 is always drivingly connected to the second electric machine 4.

(5) The transmission 2 includes a clutch K2 and another clutch K1. In addition, the transmission 2 includes a first shift element B, a second shift element A, a third shift element D, and a fourth shift element C. The first shift element B and the third shift element D are designed as a double shift element. The second shift element A and the fourth shift element C are also designed as a double shift element. The other clutch K1 and the clutch K2 are designed as a dual clutch.

(6) An output shaft 19 of the internal combustion engine VM is rotationally fixable to a first transmission input shaft 6 with the aid of the other clutch K1. In addition, the output shaft 19 is rotationally fixable to a second transmission input shaft 5 with the aid of the clutch K2. The second transmission input shaft 5 is arranged coaxially to the first transmission input shaft 6 and partially surrounds the first transmission input shaft 6.

(7) The first sub-transmission TG1 has two gear planes, in each of which a gear pair is arranged. A gear pair arranged in a first gear plane includes a first gearwheel 7 and a second gearwheel 8, which are in engagement with one each other. A second gear pair arranged in a second gear plane includes a third gearwheel 9 and a fourth gearwheel 10, which are in engagement with each other. The second gearwheel 8 and the fourth gearwheel 10 are each rotationally fixed to the first transmission input shaft 6. The first electric machine 3 is always drivingly connected to the first gearwheel 7 with the aid of a traction mechanism in the form, for example, of a chain.

(8) The second sub-transmission TG2 has two other gear planes, in each of which another gear pair is arranged. A first other gear pair arranged in a first gear plane includes a first other gearwheel 11 and a second other gearwheel 12, which are in engagement with each other. A second other gear pair arranged in a second other gear plane includes a third other gearwheel 13 and a fourth other gearwheel 14, which are in engagement with each other. The second other gearwheel 12 and the fourth other gearwheel 14 are each rotationally fixed to the second transmission input shaft 5.

(9) The second electric machine 4 is always drivingly connected to the fourth other gearwheel 14 with the aid of a traction mechanism in the form, for example, of a chain. The first electric machine 3 and the second electric machine 4 are arranged axially offset and/or axially parallel with respect to the first transmission input shaft 6 and/or the second transmission input shaft 5.

(10) The transmission 2 includes a countershaft 15. The countershaft 15 includes, as a transmission output component, an output gearwheel 16, which is engaged with a gearwheel 17 of an axle differential 18. The axle differential 18 is drivingly connected to vehicle wheels (not represented in FIG. 1). Gear shafts of the axle differential 18 extend in parallel to the first transmission input shaft 6 and the second transmission input shaft 5.

(11) The first gearwheel 7 is rotationally fixable to the countershaft 15 with the aid of the fourth shift element C. The third gearwheel 9 is rotationally fixable to the countershaft 15 with the aid of the second shift element A. The first other gearwheel 11 is rotationally fixable to the countershaft 15 with the aid of the first shift element B. The third other gearwheel 13 is rotationally fixable to the countershaft 15 with the aid of the third shift element D.

(12) With the aid of the transmission 2, a purely electric mode is possible with the aid, for example, of the first electric machine 3. In the purely electric mode, the second shift element A or the fourth shift element C is engaged and the two clutches K1, K2 are disengaged. A first gear is implemented when the second shift element A is engaged and a third gear is implemented when the fourth shift element C is engaged. In addition, with the aid of the transmission 2, a purely electric mode is possible with the aid of the second electric machine 4. In the purely electric mode with the aid of the second electric machine 4, the first shift element B or the third shift element D is engaged and the two clutches K1, K2 are disengaged. A second gear is implemented when the first shift element B is engaged and a fourth gear is implemented when the third shift element D is engaged.

(13) During the serial operation, the second shift element A and the clutch K2 are engaged and the remaining shift elements and the other clutch K1 are disengaged. In this engagement condition, the first electric machine 3 is utilized for driving the motor vehicle 1 and the second electric machine 4 is operated as a generator. The second shift element A is engaged, because there is a low ground speed during the serial operation and, therefore, the first gear is more suitable than the third gear resulting when a fourth shift element C is engaged.

(14) As soon as it is determined, for example, that the temperature of the first electric machine 3 exceeds a threshold value, the above-described change-over operation takes place. After the change-over operation, the first shift element B and the other clutch K1 are engaged and the remaining shift elements and the clutch K2 are disengaged. A serial operation is also possible in this engagement condition, wherein the first electric machine 3 is utilized as a generator and the second electric machine 4 is utilized for driving the motor vehicle 1. The first shift element B is engaged, because the second gear is more suitable at a low ground speed than the fourth gear resulting when a third shift element D is engaged.

(15) Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

(16) 1 motor vehicle 2 transmission 3 first electric machine 4 second electric machine 5 second transmission input shaft 6 first transmission input shaft 7 first gearwheel 8 second gearwheel 9 third gearwheel 10 fourth gearwheel 11 first other gearwheel 12 second other gearwheel 13 third other gearwheel 14 fourth other gearwheel 15 countershaft 16 output gearwheel 17 gearwheel 18 axle differential 19 output shaft A second shift element B first shift element C fourth shift element D third shift element K1 other clutch K2 clutch VM internal combustion engine TG1 first sub-transmission TG2 second sub-transmission