WO2017178202A1 - Drive unit and method for operation for a motor vehicle having reduced coupling complexity - Google Patents

Abstract

The invention relates to a drive unit (10) for a motor vehicle and to a method for operating a motor vehicle, comprising an electric machine (11) and a shiftable transmission (14), which has at least one speed and an idle position, and comprising a control unit (13), which is designed to control the electric machine (11) in order to control a rotational speed of the rotor (12). The transmission input shaft (15) is connected to the rotor (12) of the electric machine for conjoint rotation. A hybrid drive (20) additionally has an internal combustion engine (18), to the output shaft (19) of which the rotor (12) of the electric machine (11) can be coupled for conjoint rotation.

Description

description

Drive unit and method of operation for a motor vehicle with reduced coupling effort

The invention relates to a drive unit for a power ^¬ vehicle, a hybrid drive and a hybrid vehicle with a drive unit according to the invention and a method for operating a motor vehicle.

As hybrid vehicles are called motor vehicles, to drive a combination of an internal combustion engine and at least one electric motor are used.

Depending on the design, in various operating states of the motor vehicle, the drive power either by the

Electric motor, the internal combustion engine or a combination of both are provided. In this way, the different characteristics of electric motor and internal combustion engine can be used and combined in order to increase the processing capacity Leis ^¬ the vehicles and ride comfort while reducing fuel consumption.

The electric motor can be installed in various ways in the drive train. Known in the. "P2 line architecture", the electric machine is arranged in the drive train between the combustion engine and the transmission. That is. A rotor of the electric machine is coupled to the output shaft of the engine. In this Ar ^¬ chitecture, the electric machine can be used for Thus, the electric machine can act as a starter generator for the internal combustion engine and enable a recuperation.On the other hand, the electric machine can also be a direct allow electric starting of the vehicle. An example is known from DE 10 2014 220 862 AI.

The invention is based on the general endeavor to reduce the space required for the drive and the costs.

The object is solved by the subject matter and the method of the independent claims. Advantageous developments of the invention are specified in the dependent claims.

A drive unit according to the invention for a motor vehicle comprises an electric machine with a rotor and a switchable transmission. The transmission has at least one gear, in which a transmission input shaft and an output shaft with a fixed speed ratio are coupled to each other. The transmission further comprises at least one idling position in which the transmission ^input shaft and the output shaft are decoupled from each other ^¬ . The drive unit also includes a control unit, which is set up to control the electric machine in order to regulate a speed of the rotor. According to the transmission input shaft is rotatably connected to the rotor of the electric machine.

The electric machine may also be referred to as an electric motor and usually has a stator and a rotor or rotor. By operating the electric motor with different drive frequencies, the speed of the rotor can be influenced. The electric machine may be, for example, an external rotor machine or an internal rotor machine.

According to the rotor of the electric machine is rotatably connected to a shaft which simultaneously represents the input shaft of the transmission. A rotation and speed of the rotor is thus directly on the gear transmitted input shaft. Due to the non-rotatable connection of the rotor of the electric machine and the transmission input shaft always have the same speed. The non-rotatable connection between the transmission input shaft and the rotor is permanent and at least during operation of the on ^¬ drive unit is not solvable. The rotor of the electric machine can be made in one piece with the transmission input shaft, for example. But it may also be that during assembly several parts are joined together so that a rotationally fixed connection between the rotor and the transmission input shaft is Herge ^¬ provides, which for repair or maintenance purposes, if necessary, can be solved again. In particular, however, there is no releasable coupling element which could enable controlled decoupling during operation between the transmission input shaft and the rotor.

The output shaft carries the torque and the power transmission, for example via a differential gear on to the wheels of the vehicle. Preferably and usually, the transmission has several gears, each with different rotational ^¬ payment ratio between the transmission input shaft and output shaft. For example, the transmission has five forward gears and one reverse gear. The transmission input shaft and the output shaft are usually coupled to each other via gears. For each gear, for example, a specific gear set may be provided in the transmission, with which the transmission input shaft and the output shaft are coupled together, and by which the speed ratio between the transmission ^¬ input shaft and output shaft is set for this gear.

In addition, the transmission has an idle position in which there is no coupling of the rotational movement between the transmission input shaft and output shaft. In this state, no torque is transmitted from the transmission input shaft to the output and Transmission input shaft and output shaft can perform independent rotational movements.

The transmission is preferably a manually shiftable transmission. When changing between two gears, always go over the neutral position. However, the drive unit according to the invention or the inventive method is also conceivable with an automatic transmission, the corresponding circuit must be considered on the idle position in the automatic control.

The control unit is z. B. realized by a central control unit of the motor vehicle and is adapted to control a speed and torque of the electric machine. By selective control of the rotational speed of the electric machine can thus take over the synchronization between the output and the transmission input shaft (which is rotatably connected to the rotor of the electric machine), the electric machine. In the drive unit according to the invention, therefore, the electric machine and the control unit can jointly take on tasks that are taken over by a clutch in a conventional drive train. Usually, a clutch in the drive train serves on the one hand the interruption and coupling of the force and torque transmission and on the other hand the synchronization. The synchronization takes place here according to the invention by targeted on ^¬ control of the electric machine. The interruption and coupling of the force and torque transmission is taken over in the drive unit according to the invention by the idle position of the transmission. The drive unit according to the invention thus makes it possible to dispense with a separate coupling between the electrical machine and the transmission. In addition, the synchronization in the gearbox can be supported by synchronizing rings. Therefore, the transmission has front ^¬ preferably one or more synchronizing rings.

According to an advantageous embodiment of the invention, the transmission also has at least one speed sensor, which is set up to detect a current speed of the output shaft or a coupled to the output shaft range. For example, an area coupled to the output shaft may be a gear set for a particular gear.

Preferably, a speed sensor is provided on the respective gears for each gear. The at least one speed sensor then preferably sends a signal to the control unit corresponding to the instantaneous speed of the output shaft or a gear coupled to the output shaft for a particular gear.

The control unit, in turn, then sends a signal to the electric machine for synchronization to adjust its speed to the speed of the gear or output shaft. The speeds of the transmission input shaft and the output shaft must not be equal. Rather, depending on the selected gear, a fixed speed ratio between the output shaft and the transmission input shaft is necessary. It is crucial that the gears of transmission input shaft and gear or output shaft can mesh as gently as possible. The desired

Rotational speed of the transmission input shaft is thus defined by the ge ^¬ selected gear and by the current speed of the output shaft and the electric machine correspondingly ^¬ controls. If only one speed sensor is provided on the output shaft, the control unit can determine the required speed of the transmission input shaft based on the information about the rotational speed of the output shaft and the information about the selected gear and control the electric machine accordingly. If a separate speed sensor is provided for each gear in the transmission, the control unit can select the signal of the corresponding sensor from information about the selected gear and, depending on this, control the electric machine. ^{Corresponding} parameters or speed ratios for each gear can be stored in the control unit.

According to an advantageous development, the drive unit according to the invention is used in a hybrid drive

Motor vehicle used. This hybrid drive has an internal combustion engine in addition to the electric machine. The electric machine is in this case arranged in a drive train between the internal combustion engine and the transmission. An output shaft of the internal combustion engine is rotatably connected via a releasable coupling element with the rotor of the electric machine. The coupling element may be a friction clutch or a positive coupling element, such as a dog clutch. In this case, the synchronization between the output shaft of the internal combustion engine and the rotor of the electric machine can also be done by driving the electric machine. Preferably, the speed of the output shaft is detected by a speed sensor. When the clutch between the internal combustion engine and the electric machine is closed, the electric machine can also function as a starter generator for the internal combustion engine. The coupling can preferably also be controlled by the control unit. At lower speed and open coupling device between the engine and electric machine, the synchronization in the transmission, as described above, be done solely by controlling the electric machine and possibly existing synchronizer rings in the transmission. At higher speeds, the synchronization in the hybrid powertrain according to the invention can be done by controlling the electric motor and engine. In this case, the clutch between the engine and the electric machine is closed. Preferably, the control unit which controls the rotational speed of the electrical machine, also arranged to control the speed of the Ver ^¬ brennungsmotors.

The hybrid drive according to the invention is preferably used in a hybrid vehicle, in particular a hybrid car, which drives the hybrid drive.

The invention also relates to a method for operating a motor vehicle with a drive unit according to the invention. In the method according to the invention, the electric machine is controlled by the control unit to control a rotational speed of the rotor, so that the rotational speeds of the rotatably coupled to the rotor transmission input shaft and the output shaft ^¬ or coupled to the output shaft portion are substantially synchronized.

In a motor vehicle with a hybrid drive takes place before ^¬ preferably as a further step, the switching of a rotationally fixed connection between the output shaft of the engine and the rotor of the electric machine by a detachable

Coupling element. The coupling element can advantageously be switched by the same control unit. If it is a form-fitting coupling element, the Synchro ^¬ nization is carried out by means of the electric machine. For synchronization in the gearbox, the combustion engine is used at higher speeds in addition to the electric machine. For this, the overall coupling device on the one hand controls a torque and force transmission from the output shaft of the engine to the rotor to he ^¬ possible. Then, the internal combustion engine is controlled by the control unit in order to achieve a rotational speed of the rotor, so that the rotational speeds of the rotatably coupled to the rotor transmission input shaft and the output shaft or coupled to the output shaft portion are substantially synchro ^¬ nized.

A gear change with a drive unit according to the invention or a hybrid drive according to the invention comprises inter alia the following steps: shifting the transmission from a first gear to an idling position. Detecting a current speed of the output shaft or an area coupled to the output shaft by means of a speed sensor in the transmission.

Synchronizing the speeds of the transmission input shaft and the output shaft or a coupled to the output shaft portion using the electric machine and / or the internal combustion engine. Subsequently, shifting the transmission from the idle position to a second gear.

The terms "first gear" and "second gear" are to be understood generally as a name for two different gears, each with different speed ratio between the transmission input shaft and output shaft. The terms "first gear" and "second gear" can thus in this application also the third, fourth or any other gear of the vehicle - also the reverse gear. They are not to be understood as limiting the gears of a vehicle, referred to in general usage as first and second gear. The last step of the process, shifting the transmission from an idle position to a second gear, refers to closing the powertrain in the transmission. The selection of the second gear is preferably already before the synchronization, for example with a gear selector element.

The invention is particularly advantageous with a manually shiftable transmission. Basically, the implementation of the method in an automatic transmission is conceivable.

In the following, the invention will be explained in more detail with reference to FIGS. Show it:

Figure 1 is a schematic view of a hybrid powertrain with a drive unit according to the invention;

2 shows the course of a gear change according to an exemplary embodiment of the method according to the invention.

The hybrid powertrain 20 has an internal combustion engine 18, at the output shaft 19, a releasable coupling element 21 is arranged on ^¬ . On the other side of the coupling 21, a shaft 23 is arranged, which is rotatably connected to the rotor 12 of an electric machine 11. The clutch 21 may preferably be switched by a control unit 13. The rotor 12 of the electric machine is simultaneously non-rotatably connected to a transmission input shaft 15 of a shiftable transmission 14. The transmission 14 has at least one empty ^¬ running position, and at least one gear with a fixed speed ratio of the transmission input shaft and output shaft 16. In the transmission is a speed sensor 17th arranged, which has a current speed of the output shaft 16 or one with the Output shaft 16 coupled area detected. The output shaft 16 leads to a differential gear 22, from there the output leads to the wheels of the vehicle (not shown). Figure 2 shows schematically the course of a gear change according to the inventive method. In step SO, the process begins. The vehicle drives in a certain gear. To prepare a gear change, the torque is first taken from the drive train 20 (step S1). This is done, for example, by the driver leaving the gas pedal and taking "e-gas" from the electric motor, so that the internal combustion engine together with the non-rotatably coupled electric motor does not deliver positive or negative drive torque to the shaft by disconnecting the clutch 21 from the driveline 20. Once the transmission input shaft 15 is free of torque, the transmission 14 can be placed in an idle position by the driver by means of a gear selector element (step S2.) The powertrain 20 is thus controlled by the driver in the transmission 14 Then, in step S3, a second gear is entered through

Gear selection element, eg a shift lever preselected. About a gear selection the information about the selected gear is transmitted to the control unit 13. In step S4, an instantaneous rotational speed of the output shaft 16 or an area coupled to the output shaft is then detected. When the rotational speed of the output shaft 15 is detected, the control unit 13 can determine from the information about the selected gear a "target speed" for the transmission input shaft 15. If a separate speed sensor 17 is present in the transmission 14 for each gear, the control unit 13 determine the respectively relevant speed sensor 17 whose signal is to be processed on the basis of the information about the selected gear. game, the rotational speed of a ge to the output shaft 16 coupled ^¬ gear gearwheel. In this case, the STEU ^¬ ereinheit 13 determines from the "nominal speed" of the transmission input shaft 15th

The "target rotational speed" of the transmission input shaft 15 is measured, for example, by the fact that a sprocket rotating with the transmission input shaft 15 can engage as gently as possible with the selected sprocket gear

Transmission input shaft 15 and output shaft 16, which is e.g. is stored in the control unit 13.

In the next step S5, the output shaft 16 and the transmission input shaft 15 are synchronized accordingly. For the electric machine 11 is controlled by the control unit 13 so that the runner with the desired

At higher speeds, in addition to the electric machine 11, the internal combustion engine 18 is also driven accordingly and the clutch 21 is closed.

Finally, in step S6, the drive train in the transmission is closed again with the preselected gear. The gear change is complete. The steps S2 and S3 are performed in a manual transmission by a driver by means of a gear selector element.

In principle, the steps S2 and S3 can also be summarized, as long as it is ensured that although the following gear is already preselected, in the transmission but the drive train remains open until the synchronization has taken place.

Otherwise, the steps S3 and S4 can also be performed in reverse order, by first a speed the output shaft 16 is detected and then selected before the Synchro ^¬ nisation the next gear.

Reference sign list

10 drive unit

 11 electric machine 12 runners

 13 control unit

 14 gears

 15 transmission input shaft

16 output shaft

17 speed sensor

 18 combustion engine

19 output shaft

 20 hybrid drive

 21 clutch

22 differential gear

23 wave

Claims

claims A drive unit (10) for a motor vehicle,  comprising:  an electric machine (11), with a rotor (12), a switchable transmission (14), which has at least one gear, in which a Ge ^¬ transmission input shaft (15) and an output shaft (16) are coupled to each other with a fixed speed ratio, and which has at least one idle position, in which the transmission input shaft (15) and the Ab ^¬ drive shaft (16 ) are decoupled from each other,  characterized in that  - The drive unit further comprises a control unit (13) which is arranged, the electric machine (11) to control a speed of the rotor (12), and  that the transmission input shaft (15) rotatably with the rotor (12) of the electrical machine (11) is connected. 2. Drive unit (10) according to claim 1, wherein in the  at least one gear of the shiftable transmission (14) the transmission input shaft (15) and the output shaft (16) via gears with a fixed speed ratio are coupled to each other. 3. Drive unit (10) according to one of the preceding claims ^¬,  wherein the transmission (14) has at least one rotational speed sensor (17), which detects a current Speed of the output shaft (16) or one with the Ab ^¬ drive shaft (16) coupled area is established. 4. Hybrid drive (20) for a motor vehicle having an Ver ^¬ brennungsmotor (18) and a drive unit (10) according to one of the preceding claims, wherein the electrical machine (11) is arranged in a drive train between the combustion engine (18) and the transmission (14), and an output shaft (19) of the Ver ^¬ brennungsmotors (18) via a detachable coupling element (21) (with the slide 12 ) of the electrical machine (11) is rotatably connected. 5. Hybrid drive according to claim 4,  wherein the control unit (13) is further configured to control a rotational speed of the internal combustion engine (18). 6. hybrid drive according to one of claims 4 and 5, wherein the control unit (13) is arranged, while the transmission (14) is in idle position, the electric machine (11) and / or the internal combustion engine (18) to control that Transmission input shaft (15) and the output shaft (16) are substantially synchronized. 7. hybrid drive (20) according to one of claims 4 to 6, wherein the coupling element (21) is a positive coupling element Kupp ^¬ (21). 8. Hybrid vehicle, in particular hybrid car, which has a Hyb ^¬ ridantrieb (20) according to one of claims 4 to 7, with which the hybrid vehicle is driven. 9. A method of operating a motor vehicle with a  Drive unit according to one of claims 1 to 3, with the step: - Driving the electric machine (11) by means of the control unit (13) by a speed of the rotor (12) so that the rotational speeds of the rotationally fixed coupled to the rotor (12) transmission input shaft (15) and the output shaft (16) or a coupled to the output shaft (16) portion are substantially synchronized. 10. A method for operating a motor vehicle according to claim 9, wherein the motor vehicle has a hybrid drive (20) according to one of claims 4 to 7,  with the step: Switching a rotationally fixed connection between the output shaft of the internal combustion engine (18) and the rotor (12) of the electric machine (11) by a releasable Kupp ^¬ ment element (21). 11. A method for operating a motor vehicle according to claim 10, with the additional step:  - Controlling of the internal combustion engine (18) by means of the control unit (13) to control a speed of the rotor (12), so that the rotational speeds of the rotor (12) rotatably coupled to the transmission input shaft (15) and the output shaft (16) or one with the output shaft (16) coupled portion are substantially synchronized. 12. A method of operating a motor vehicle according to any one of claims 9 to 11, comprising the steps of:  Shifting the transmission (14) from a first gear to an idling position,  - Detecting a current speed of the output shaft (16) or coupled to the output shaft (16) range by means of a speed sensor (17) of the transmission. - Synchronizing the speeds of the transmission input shaft (15) and the output shaft (16) or one with the Ab- drive shaft (16) coupled region by means of the electric machine (12) and / or the internal combustion engine (18),  - Switching the transmission (14) from the idle position to a second gear.