Patent Application
20110124455
The invention concerns a hybrid drive train of a motor vehicle which comprises a combustion engine with a drive shaft, an electric machine which can be operated as either a motor or a generator, a stator as well as a rotor, and a multi-stage planetary automatic transmission with an input shaft and an output shaft, whereby the drive shaft of the combustion engine is drivingly connected via a controllable separating clutch, and the rotor of the electric machine, via an input transmission section, is drivingly connected with the input shaft of the automatic transmission.
A hybrid drive train in a motor vehicle, with a parallel operating configuration of a combustion engine and an electric machine, can be designed geometrically, from the drive technology standpoint as a configuration with a succeeding, multistage gear box, in a very simple manner, so that the electric machine is coaxially positioned on the input shaft of the gear box, the rotor of the electric machine is connected in a rotationally fixed manner with the input shaft of the gear box, and the drive shaft of the combustion engine can be connected with the input shaft of the gear box by means of a controllable, meaning an engaging/disengaging, separating clutch. The electric machine can, in this case, be forceless shifted during the drive operation, to use it either as a generator to charge the electric energy storage device, or as an electric motor to drive the motor vehicle. When applied as a motor, the electric machine can be used with the engaged separating clutch, especially in a larger acceleration and when driving on a steep uphill slope, to support the combustion engine in the so-called boost operation, and with a disengaged separating clutch especially during a starting and when driving in inner city areas with emission restrictions, using it as the only drive motor in a pure electric operation.
Such a hybrid drive train with a gear box, designed as a planetary automatic transmission, for instance, is known through the DE 103 46 640 A1. In both variations of this known hybrid drive train is, in accordance with the
An additional kind of a hybrid drive train with a gear box, designed as a planetary automatic transmission, has been described with different embodiments in DE 10 2004 043 589 A1. While the first variation of this known hybrid drive train, based on its shown
Generally, it is a disadvantage in the previously mentioned hybrid drive trains that the level of the rotation speed of the electric machine which is connected with the input shaft matches the rotation speed of the combustion engine, and that therefore the related electric machine, to achieve the necessary drive power for a pure electric drive condition, needs to be designed as being large and heavy.
By using an axially parallel configuration with the related electric machine and a driving connection of the rotor of the electric machine with the input shaft of a gear box via an input transmission section with a gear ratio iEK>>1, like a spur gear or a continuously variable transmission, the electric machine can hereby designed as being significantly less powerful and therefore small and lightweight.
Such a hybrid drive train is, for instance, known through DE 100 12 221 A1 with two embodiments. In both embodiments of this known hybrid drive train and in accordance with
However, in this known hybrid drive train the radial dimensions are so large, especially in the area of the electric machine and the input transmission section, that this hybrid drive train cannot be integrated, without larger modifications to the vehicle body of the motor vehicle. In addition, due to the gear ratio of the input transmission section, the rotational speed of the rotor of the electric machine can be so high, that an unfavorably large effort is required for a rotational speed-proof design, as well as for the balancing and the bearing of the rotor.
Therefore, a requirement exists for a hybrid drive train of a motor vehicle which can be integrated with a motor vehicle by the use of an adequate electric machine for a pure electric operation, without modifications of the vehicle body as an alternative to a conventional drive train which comprises an automatic transmission with a hydrodynamic torque converter in front of it.
Thus, it is the task of the present invention to present a hybrid drive train as previously described, which matches in a simple and space saving construction and without any functional restrictions, the dimensions of a conventional drive train with hydraulic dynamic torque converters. In addition, a suitable bearing for the rotor of the applied electric machine shall be presented.
To solve the given task, the invention is based on a hybrid drive train of a motor vehicle, which comprises a combustion engine with a drive shaft, an electric machine used as a motor or generator with a stator and a rotor, and with a multistage planetary automatic transmission with an input shaft and an output shaft, whereby the drive shaft of the combustion engine, via a controllable separating clutch, and the rotor of the electric machine, via a transmission input section, are drivingly connected with the input shaft of the automatic transmission. It is also provided, in accordance with the invention, that the electric machine, the separating clutch, and the transmission input section are coaxially positioned in a module enclosure which can be preassembled with an input element and an output element, whereby the input element is connected in a rotationally fixed manner with the drive shaft of the combustion engine, and the output element is connected in a rotationally fixed manner with the input shaft of the automatic transmission, and the hybrid module matches the dimensions of a conventionally used hydrodynamic torque converter.
Therefore, the invention is essentially an assembled unit which represents a hybrid module, comprising of the electric machine, the separating clutch, and the transmission input section, whereby, due to the coaxial positioning of these parts, an especially compact construction is achieved, through which the dimensions of an existing hydrodynamic torque converter, in a conventional drive train, can be maintained without any decrease in the functionality.
The input element of the hybrid module is, analogous to the pump wheel shaft of a torque converter, practically designed as a shaft or a flanged shaft, which can be, for instance, during the assembly of the hybrid drive train, connected in a rotationally fixed manner through a plug-in connection or screw type flange, respectively, with the crankshaft of the combustion engine or with one of its connected flywheels. Analogous to the turbine wheel hub of a torque converter, it is also practicable if the output element of the hybrid module is designed as a hub which, for instance, can be connected in a rotationally fixed manner during the assembly of the hybrid drive train via an interlock gearing with the axially protruding input shaft of the automatic transmission.
The hybrid drive train, in accordance with the invention, differs only, apart from a larger energy storage for the electric machine which can be positioned at a different location within the motor vehicle, for instance under the backseat or in the trunk, from a conventional drive train through the provided hybrid module, instead of the hydrodynamic torque converter. The planetary automatic transmission of the conventional drive train can be maintained in the invented hybrid drive train without any changes, whereby, contrary to known hybrid drive trains, a large number of gear steps and a large spread are available. In addition, due to the total, larger production quantity of the consolidated automatic transmission, significant cost advantages arise as compared to known solutions with specific transmission configurations. Advantageous is also, in regard to the integration of the invented hybrid drive train with a motor vehicle, that no modification of the vehicle body is required.
To achieve compact dimensions of the hybrid module, it is preferably provided that the electric machine is designed as an inner, radially positioned rotor, inside of the stator, and that the separating clutch is axially positioned on the motor side and that the input transmission section is axial, in reference to the transmission, radial positioned within the rotor.
To effectively diminish the unavoidable, torsional vibrations of the crankshaft, generated by the drive shaft of a piston engine, the input element of the hybrid module can also be designed as two parts which are rotatable to a limited extent, which are connected with each other via a torsional vibration damper. Hereby, the torsional vibration damper is also a part of the hybrid module and can be positioned axially, on the motor side, either radially inside or at least close to the rotor of the electric machine.
To achieve, on one hand, a compact configuration and, on the other hand, a preferably high efficiency of the electric machine, the input transmission section is appropriately designed with a transmission ratio IEK between 1.2 and 1.7 (1.2<IEK<1.7).
Such a transmission ratio IEK, in connection with compact dimensions, can be achieved by designing the input transmission section as a simple planetary gear wheel set which has a sun gear, with several pivotable planetary gear wheels which are circumferentially distributed and positioned on a planetary carrier, where the planetary wheels also intermesh with a ring gear, whereby the sun gear is fixed in position opposite to the module enclosure, the ring gear is connected in a rotationally fixed manner with the rotor of the electric machine, and the planetary carrier is connected in a rotationally fixed manner with the output element of the hybrid module.
The transmission ratio IEK of the input transmission section is, depending on the particular number of teeth, exactly between 1.25 and 1.67 (1.25<IEK<1.67). An advantage of that design of the transmission input section is also the relatively low rotational speed between the rotating parts, like between the sun gear and the planetary carrier, and between the planetary carrier and the ring gear, which hereby results altogether in a high efficiency transmission.
The rotor of the electric machine can be pivoted, in a simple and space saving way through a double shear bearing, comprising an axially fixed bearing at the motor side of the input transmission section, and an axially positioned non-locating bearing at the transmission side of the input transmission section, opposite to the module enclosure and/or at a pivoted part within the module enclosure.
At least one of the bearings, meaning the fixed bearing and/or the non-locating bearing of the rotor of the electric machine, is practically designed as a rolling bearing, which supports itself radially inside on an enclosure mounted outer cylindrical bearing seat, which can, for instance, be part of a bearing shield which is a fixed part with the enclosure.
However, the non-locating bearing of the rotor can also be designed as a rolling bearing which supports itself radially inside on an external, cylindrical bearing seat, which is mounted at a part that is connected in a rotationally fixed manner with the output element of the hybrid module, such as a driving element of a hydraulic pump, driven by the output element. The generated radial forces of the non-locating bearing are, in this case, transmitted via the bearing of the output element of the hybrid module into the module enclosure.
The rolling bearing which is used as the fixed bearing and/or the non-locating bearing, are each preferably designed as deep groove ball bearings. A standardized deep groove ball bearing is robust as well as inexpensive, and can, due to the design and load directions, be applied as a non-locating bearing as well as a fixed bearing.
The non-locating bearing of the rotor of the electric machine can also be designed especially advantageous through the gearings and bearings of the parts of the input transmission section, whereby the construction space and the cost for a separate roller bearing can be spared. Through this preferred design of the input transmission section as a simple planetary gear set, the generated radial forces of the non-locating bearing are mainly transmitted by the rotor of the electric machine via the gearing of the ring gear and from the planetary gears to the planetary carrier, and from here transmitted via the bearing of the output element of the hybrid module into the module enclosure.
However, as an alternative to a double shear bearing, the rotor of the electric machine can also be pivoted positioned by means of a single fixed bearing, axially positioned at the motor side of the input transmission section, which is opposite the module enclosure, or at a pivoted part which is within the module enclosure. Axial stress which is generated by the input transmission section or the ring gear of the planetary gear wheel set, respectively, is compensated in this bearing design through axial movement of the ring gear and, if required, through the planetary gear wheels which are opposite to the planetary carrier and/or through an elastic information of the rotor of the electric machine.
The fixed bearing of the rotor is practically configured by means of a rolling bearing configuration, which supports itself, radially inside, on an enclosure mounted, outer cylindrical bearing seat.
To be able to accommodate, beside the usual occurrence of radial and axial forces, also the tilting and bending torque of the rotor which is caused by the operation, the fixed bearing of the rotor is in this case preferably designed as a double-row angular ball bearing, or as an adjusted bearing with two tapered roller bearings.
For a further clarification of the invention, drawings are attached to the specification with examples of the embodiments. It is shown in
The invented drive train as in
The automatic transmission 1 comprises a partial transmission 7 on the input side and a partial transmission 8 on the output side which is positioned between the input shaft 2 and the output shaft 3 which are switchable through a selective engagement of the shift-clutches C1, C2, C3, and to shift brakes B1, B2.
The partial transmission 7 on the input side is designed as a simple planetary gear assembly 9 with a sun gear 11, which is fixed in position with reference to an enclosure 10, with a group of planetary gears 12, which mesh with the sun gear 11 and which are together rotatably positioned on the planet carrier 13, and with a ring gear 14 which meshes with the planetary gears 12 and which is permanently, connected in a rotationally fixed manner with the input shaft 2.
The partial transmission 8 on the output side is designed as a Ravigneaux gear set 15, with a first, radially small sun gear 16 which meshes with a first group of axially shorter planetary gears 17, with a second radial larger sun gear 18 which meshes with a second group of axially longer planetary gears 19, which each mesh with one of the axially shorter planetary gears 17, with a planet carrier 20 on which the axially shorter planetary gears 17 and the axially longer planetary gears 19 are rotatably positioned, and with a ring gear 21 which meshes with the axially longer planetary gear 19 and which is permanently, connected in a rotationally fixed manner with the output shaft 3.
The radially smaller sun gear 16 can be connected, by means of the first shift clutch C1, selectively with the planetary carrier 13 of the partial transmission 7 at the input. The radially larger sun gear 18 can be connected, by means of the second shift clutch C2, selectively with the planetary carrier 13 of the partial transmission 7 at the input. The planetary carrier 20 at the output side can be connected, by means of the third shift clutch C3, selectively with the input shaft 2. The radially larger sun gear 18 can be locked by means of the first shift brake B1, opposite in reference to the enclosure 10. Finally, the planetary carrier 20 can be locked by means of the second shift brake B2, opposite in reference to the transmission enclosure 10.
This known automatic transmission has six forward gear steps G1 to G6 and one reverse gear step R, each can be shifted through the selective engagement of two shift elements, meaning two of the shift clutches C1, C2, C3 and the shift brakes B1, B2.
The hybrid module 4 comprises an electric machine EM, designed to work as a motor and as a generator, and a controllable, meaning an engaging and disengaging, separating clutch C0 for the required connecting or disconnecting of the combustion engine which is in a driving connection with the input element 5. The electric machine EM is designed as an inner rotor and a radially, outer stator 23, attached to the module enclosure 22, as well as a rotor 24 which is positioned radially within the stator 23.
The rotor 24 is in driving connection, via the input transmission section 25, with the output element 6. The input transmission section 25 is designed as a simple planetary gear set 9 and, at the transmission side, axially positioned coaxial within the cavity of the electric machine EM which is formed by the rotor 24. The input transmission section 25 comprises a sun gear 26 which is permanently attached to the module enclosure 22, a group of planetary gears 27 which mesh with the sun gear 26 and which are rotatable positioned on a common planetary carrier 28, and a ring gear 29 which meshes with the planetary gears 27 and which is permanently, connected in a rotationally fixed manner with the rotor 24 of the electric machine EM. The input transmission section 25 represents therefore a gear ratio iEK, which varies between 1.25 and 1.67 (1.25<iEK<1.67).
The separating clutch C0 which is connected on the input side, via a torsional vibration damper 30, in a rotationally fixed manner with the drive shaft of the combustion engine (not shown here) and its input element 5, and connected on the output side directly with the output element 6 of the hybrid module 4, and is axial positioned, on the motor side, coaxial within the rotor 24 of the electric machine EM.
Due to the design and the positioning of the electric machine EM, the separating clutch C0, and the input transmission section 25, the hybrid module 4 maintains, without any functional restrictions, the dimensions of a hydrodynamic torque converter of a conventional drive train. The inventive hybrid drive train as in
In
In the embodiment of the hybrid module 4 in accordance with
In the variation of the hybrid module 4, in accordance with
In a variation of the hybrid module 4 in accordance with
In the variations of the hybrid module 4 in accordance with
The roller bearing configuration in the embodiment as in accordance with
| Number | Date | Country | Kind |
|---|---|---|---|
| 102008040498.5 | Jul 2008 | DE | national |
This application is a National Stage completion of PCT/EP2009/059146 filed Jul. 16, 2009, which claims priority from German priority application serial no. 10 2008 040 498.5 filed Jul. 17, 2008.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/059146 | 7/16/2009 | WO | 00 | 12/17/2010 |
