DE19958403A1 - Hybrid drive train for vehicle; has internal combustion engine, electric motors and balancing planetary gear and electric motor to generate torque and compensate jerking movement in crankshaft - Google Patents

Abstract

The drive train has a balancing planetary gear (4) and at least two electric motors (2,3). The rotor (18) of the first electric motor can be connected to the sun gear of the balancing gear. The rotor (28) of the second electric motor can be connected to the ring gear of the balancing gear and a driven shaft. A crankshaft (13) can be connected with the sun gear. The driven shaft can be driven by the internal combustion engine or by the second electric motor. At least one sensor (8) outputs signals of the variation in angle position of the crankshaft to the control unit (32), which is compensated by controlling the first electrical machine to generate an electrical torque. The planetary gear is torque-free to rotate the crankshaft from its defined rest angle position, to prevent rotations.

Description

The invention relates to a hybrid drive train for Motor vehicles according to the preamble of claim 1.

This is a so-called hybrid drive, which either from an internal combustion engine and / or at least one electrical machine can be driven.

A motor vehicle drive train according to the preamble of Specified claim 1 is known from EP 0839683 A2. It contains a planetary gear, a first motor generator, a second motor generator and a computerized one electronic control device for the internal combustion engine and the electric motor generator machines. The electrical Motor generator machines are also referred to below as EM designated. The rotor of the first EM is with the sun gear of the Planetary gear, the rotor of the second EM is one Output shaft of a planet carrier of the planetary gear and the crankshaft of an internal combustion engine is with the Planet carrier of the planetary gear connected. In response on an internal combustion engine stop instruction Fuel supply to the internal combustion engine is interrupted Vehicle powered by the second EM and the first EM by the control device is controlled to the rotation of the Counteracting torque on the crankshaft Generate planetary gear until the speed of rotation Crankshaft becomes zero. There are rotation angle measuring devices for this for measuring the angle of rotation of the sun gear, the ring gear, and the planet carrier of the planetary gear provided.

The known drive train is intended to solve the problem of reducing the speed of the internal combustion engine to zero in a very short time after the fuel supply has been switched off, so that the resonant frequency range of the engine, which can lead to disadvantageous vibrations in the entire drive train and vehicle, as quickly as possible is going through. When the crankshaft has reached zero speed, the second EM is no longer activated by the control device in order to compensate the dynamic influences of the internal combustion engine with a counter torque. Only the first EM is continuously brought up to speed by the control device, which guarantees the resulting zero speed on the motor. However, the rule requirement is even stricter; because beyond the zero speed, the crankshaft must be kept in its neutral rest position, so that there is no rumbling over the compression dead center due to drag torque of the EM 1 or its inertia when the vehicle speed changes.

The present invention relates not only to hybrid drives a planetary gear, but all hybrid drives which is an internal combustion engine and electrical machines (Electric motor, generator, or preferably combined electric motor generator machines) via one Differential gear (planetary gear, differential gear, Branching gear) are coupled to one another in terms of drive.

To reduce fuel consumption, the Internal combustion engine switched off and the motor vehicle only from one or more of the electrical machines, as Electric motor operated, which are driven by their energy obtained from an electric battery. Furthermore, too Versions possible, in which the vehicle with increased Power requirement from the internal combustion engine and at the same time from at least one EM can be driven. The "switch off" of the internal combustion engine means that an inoperative state is turned on, in which the internal combustion engine none Fuel consumed more. This can be done by interrupting the Fuel supply and / or by switching off the electrical  Ignition device of the internal combustion engine take place.

If the output shaft when the internal combustion engine is switched off of the drive train only from the second, as an electric motor powered electric machine is powered, then should the rotor of the first electrical machine from that Planetary gears are not dragged along, but relatively to the planetary gear remain torque-free so that Crankshaft of the internal combustion engine no drag torque exerted becomes. Such a drag torque can occur on the crankshaft Generate jerky movements, especially with strong ones Torques when accelerating or decelerating Motor vehicle.

Such jerking movements of the internal combustion engine should be prevented a) because of the comfort-reducing reaction on the drive train and the vehicle occupants and b) because the operational safety and service life of the drive elements, which natural frequencies have, for example the Natural frequencies of the crankshaft, the drive shaft containing gimbal, and an internal combustion engine Timing chain.

However, the first EM carried as a generator is based on that Differential gear is not torque-free, it has one considerable on the differential Drag torque, which increases with increasing speed, and it especially has a very large one, via the differential acting moment of inertia, which causes that at Acceleration and braking of the vehicle Rotor speed of the first EM wants to remain constant zero, so that on the differential on the crankshaft of the Torque acting internal combustion engine is created by which the crankshaft from its standstill rotational angle position can be turned out.

The object of the invention is to be achieved  Jerky movements of the crankshaft from its standstill Prevent angle of rotation position or at least strong to reduce if the vehicle is turned off Internal combustion engine powered by an electrical machine becomes.

This object is achieved according to the invention by the characterizing features of claim 1 solved.

With the invention, the crankshaft is always in the same Compression valley held between the past and the next following compression torque peak.

Accordingly, the motor vehicle powertrain is according to the Invention characterized in that at least one Sensor means is provided, which in the second Operating mode after the engine output shaft a predetermined Has reached the rest position angle of rotation, depending on Torque effects in the drive train of the control device Supplies signals, depending on which the first electrical machine can be controlled by the control device is to generate an electric torque through which this first electric machine towing and its own Moments of inertia at least partially compensated and thereby remains essentially torque-free on the differential or becomes torque-free to avoid twisting of the Motor output shaft from the defined rest position Prevent angle of rotation position or such Counteracting twists.

Thus, the mentioned jerk movements of the crankshaft remedied the invention in that at least one Angle position transmitter any control device Deviations of the crankshaft from a predetermined rest position reports and that depending on it in the first electrical An electric torque is generated which the machine Friction, inertia and other drag moments of this  first electrical machine compensated so that again and again the initial resting position of the crankshaft is adjusted.

The control device is preferably a computerized one electronic device for controlling and / or regulating the electrical machines and preferably also the Internal combustion engine. For this purpose, it preferably contains corresponding programs (engine management, etc.).

The deviations mentioned are from the control device preferably via power electronics in a Corrective movement of the first electrical machine is converted, so that this first electrical machine actively participates in it even with strong vehicle accelerations or decelerations from her no torque on the power split transmission is exercised so that the crankshaft in its predetermined Rest position remains or when deflected from this Turns the rest position back to the rest position.

Corrected oscillations of the crankshaft by the control engineering timeframes have none disruptive influence on the drive train, since the Angular deflections of the crankshaft far below +/- 15 degrees can be held. The neutral rest position finds the Crankshaft when switching off the internal combustion engine in that targeted when turning down the speed into a certain one Angular position is brought. This angular position is then Control engineering always complied with by the aforementioned Function of the first electrical machine through which is prevented that this first electrical machine essential torque on the power split transmission exercises when the vehicle is powered by the second electrical machine is driven with the internal combustion engine switched off.

The angular position encoder can be with the crankshaft or with be coupled or interact with another element to Example optically or electromagnetically or in another way,  which is in rotary drive connection with the crankshaft.

The invention will now be described with reference to the accompanying Drawing using a preferred embodiment as an example described. The drawing shows in

Fig. 1 shows schematically a hybrid drive train according to the invention for motor vehicles.

The hybrid drive train for motor vehicles contains an internal combustion engine 1 , a first electrical machine 2 , a second electrical machine 3 , a differential gear in the form of a planetary gear 4 , an output shaft 5 , a rear axle differential gear 6 , a connecting the output shaft 5 to the rear axle differential gear 6 Cardan shaft 7 , and an angular position encoder 8 .

The planetary gear 4 contains a planet carrier 10 , which is connected or can be connected to the crankshaft 13 of the internal combustion engine 1 via a planet carrier shaft 12 or is an integral part of this crankshaft 13 .

A sun gear 14 of the planetary gear 4 is connected or connectable to the rotor 18 of the first electrical machine 2 via a hollow sun gear shaft 16 , through which the planet carrier shaft 12 extends. The stator 20 of the first electrical machine 2 is arranged non-rotating relative to a housing 21 .

A ring gear 22 of the planetary gear 4 is drivingly connected or connectable to the output shaft 5 and is arranged on the gear side facing away from the planet carrier shaft 12 .

With the sun gear 14 and ring gear 22 are planetary gears 24 of the planet carrier 10 in meshing engagement.

The second electrical machine 3 has a rotor 28 which is connected or connectable in a rotationally fixed manner to the output shaft 5 and a stator 30 which is arranged non-rotatably relative to the housing 21 .

"Drive connected or connectable" means in the Description and claims that a Rotary drive connection is present or through a Switching element can be produced, for. B. by a clutch.

A control device 32 , which is preferably computerized, is connected to the angular position transmitter 8 and to the two electrical machines 2 and 3 via electrical lines and preferably contains power electronics for operating the two electrical machines 2 and 3 .

The two electrical machines 2 and 3 can optionally be used as an electrical motor or as an electrical generator, as is known from the prior art. For the explanation of the present invention, only the description of the following two operating modes is necessary: a first operating mode, in which the output shaft 5 and thus also the planetary gear 6 from the internal combustion engine (alone or in combination with one and / or the other of the two electric ones Machines 2 and 3 ) is driven, and a second operating mode in which, when the internal combustion engine 1 is switched off, the output shaft 5 is only driven by the second electrical machine 3 . "Switched off" means that no fuel is supplied to the internal combustion engine 1 or that it does not take up any fuel and that the crankshaft remains in a predetermined rest position rotational angle position because it is not driven by the internal combustion engine 1 . In both operating modes, there is the possibility of an overrun mode, in which the output shaft 5 is driven by the vehicle wheels (idling, downhill, braking mode).

In the second operating mode of the control device 32 , the angular position position transmitter 8 reports whether the crankshaft 13 is in the predetermined rest position rotational angular position or has been turned out in one or the other direction of rotation thereof by a torque possibly acting on the crankshaft from the planetary gear 4 .

The first electrical machine 2 can be controlled by the control device 32 in such a way that it generates an electrical torque, by means of which it remains largely torque-free on the planetary gear 4 , that is to say that the planetary gear 4 cannot exert any significant torque on it, so that the planetary gear 4 can also exert no significant torque on the crankshaft 13 in the predetermined rest position rotational angle position. Adverse jerking movements of the crankshaft 13 are thus avoided.

In Fig. 1, the angular position encoder 8 is coupled to the crankshaft 13 , for example electromagnetically or capacitively or in another known manner. The angular position encoder 8 can have a fixed sensor 8-1 and an element 8-2 interacting therewith or a marking on the crankshaft 13 .

According to other embodiments, however, the angular position encoder 8 need not be coupled to the crankshaft 13 . The same function can be achieved if the angular position position sensor 8 cooperates functionally with another element which is in rotary drive connection with the crankshaft 13 , for example the planet carrier 10 of the planetary gear 4 or a belt drive or chain drive of the internal combustion engine 1 .

It can be seen that, in addition to an angular position sensor 8 , other sensors and measuring devices can also be used, in particular torque sensors on the crankshaft 13 or on another element connected to it in rotary drive, e.g. B. on the sun gear shaft 16 to generate a torque in the second electrical machine 2 , by means of which the crankshaft 13 is held in its predetermined rest position rotational angle position or is rotated back into it at deflections therefrom. Here there is the possibility of counteracting not only in the event of deviations from the rest position angle of rotation position, but also beforehand if there is a tendency to do so by means of a compensating electrical torque in the first electrical machine 2 .

According to another embodiment, the crankshaft 13 is not held exactly in the rest position angle of rotation position, but within a predetermined rest position rotation angle range. In the claims, the term rest position angle of rotation position also includes such a tolerance range of z. B. maximum +/- 15 °.

The internal combustion engine 1 can be a gasoline engine or a diesel engine with a crankshaft.

The drag torque of the first electrical machine 2 increases with increasing speed, and the mass moment of inertia of this first electrical machine 2 is greater, the greater the acceleration or deceleration torques in the differential gear 4 . Electrical torques generated in the first electrical machine to compensate for this are therefore speed, direction of rotation, acceleration and deceleration dependent. All of these criteria are taken into account in a simple manner at the same time in accordance with the invention in that the angular position transmitter 8 informs the control device 2 in the manner mentioned whether the crankshaft 13 is in the predetermined rest position angular position when the internal combustion engine is switched off or in one or the other direction of rotation has been.

Claims (4)

1. Hybrid drive train for motor vehicles, comprising a differential ( 4 ), at least one first electrical machine ( 2 ), at least one second electrical machine ( 3 ), a control device ( 32 ), the rotor ( 18 ) of the first electrical machine ( 2 ) with a first reaction part ( 14 ) of the differential gear ( 4 ), the rotor ( 28 ) of the second electrical machine ( 3 ) with a second reaction part ( 22 ) of this differential gear ( 4 ) and with a gear output shaft ( 5 ), and a motor output shaft ( 13 ) with a third reaction part ( 14 ) of the differential gear ( 4 ) is connected or connectable in each drive, a first operating mode for driving the transmission output shaft ( 5 ) from the switched-on internal combustion engine ( 1 ) and a second operating mode for driving the transmission output shaft ( 5 ) from the second electrical machine (3) are provided with shut-off internal combustion engine (1), characterized in that at least one sensor means (8) is provided, which provides (32) signals in the second mode after the motor output shaft has reached (13), a predetermined rest position angular position in response to rotational angle changes of position of the crankshaft of the control means, electric, depending on which the first Machine ( 2 ) can be controlled by the control device ( 32 ) in order to generate an electrical torque, by means of which this first electrical machine ( 2 ) at least partially compensates for its own drag and moment of inertia and thereby remains essentially torque-free on the differential ( 4 ) or is torque-free in order to prevent twists of the motor output shaft ( 13 ) from the defined rest position angle of rotation position or to counteract such twists. 2. Hybrid drive train according to claim 1, characterized in that the sensor means has at least one angular position encoder ( 8 ) which reacts to the angular positions of the motor output shaft ( 13 ) or an element connected to the rotary drive. 3. Hybrid drive train according to claim 1 or 2, characterized in that the differential gear ( 4 ) is a planetary gear. 4. Hybrid drive train according to one of the preceding claims, characterized in that the control device ( 32 ) is designed such that by controlling the first electrical machine ( 2 ), in the second operating mode when the internal combustion engine ( 1 ) is switched off, deviations of the motor output shaft ( 13 ) are kept from their rest position angle of rotation position within a range of rotation angle of less than +/- 15 degrees.