DE102010028023A1 - Method for operating drive train of hybrid drive of motor car, involves partially balancing tensile interruption of combustion engine using mechanical rotor moment of electric machine during switching such that friction clutch is operated - Google Patents

Abstract

The method involves degrading a tensile force provided by an internal combustion engine (3) in a first phase. A switching is executed in a second phase. The tensile force is again constructed in a third phase. A tensile interruption of the combustion engine is partially balanced using a mechanical rotor moment of an electric machine (7) of a drive unit during switching such that a friction clutch (9) between the electric machine and an output shaft (1) is operated, where the combustion engine is connected to the output shaft over an automated gearbox.

Description

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

The main components of a drive train of a motor vehicle are a drive unit and a transmission. The transmission converts speeds and torques and thus provides a traction power supply of the drive unit at a power take-off of the drive train ready. The present invention relates to a method for operating a drive train of a hybrid vehicle, the drive unit comprises at least one electric machine and an internal combustion engine, wherein the internal combustion engine is coupled via an automated transmission to an output, and wherein in the automated transmission with interruption of the combustion engine on Downforce provided traction circuits are executed. Such circuits with interruption of the traction provided by the engine at the output are carried out so that initially reduced in a first phase provided by the engine at the output tractive force, then executed in a second phase, the actual circuit or a gear change in the manual transmission and subsequently in a third phase which provided by the internal combustion engine at the output tractive force is reduced again. Such a power interruption is perceived by a driver as uncomfortable or unsportsmanlike.

In a drive train of a hybrid vehicle whose drive unit comprises at least one electric machine in addition to the internal combustion engine, it is basically possible to at least partially compensate for the interruption of the traction provided by the engine at the output during the circuit execution, that of the electric machine of the drive unit at the output Traction is provided.

The electric machine of the drive unit of the hybrid vehicle provides such a tensile force on electrical way, wherein the electric motor provided by the electric traction or the corresponding drive torque from the electric machine, a cooperating with the same inverter and cooperating with the same electrical energy storage depends on or is limited.

Up to now, there is no possibility of making a compensation of a traction interruption of the internal combustion engine beyond the tractive force which can be provided by the electrical machine by electrical means.

On this basis, the present invention based on the problem to provide a novel method for operating a drive train.

This problem is solved by a method according to claim 1. According to the invention, the traction interruption of the internal combustion engine is at least partially compensated by a function using a mechanical flywheel torque of the electric machine of the drive unit that a frictionally engaged between the electric machine of the drive unit and the output friction clutch is operated slipping.

With the present invention, it is proposed for the first time to at least partially compensate for a traction interruption of the internal combustion engine when executing a circuit, that a mechanical momentum moment of the electric machine is used by a friction clutch operated between the electric machine of the drive unit and the output driven slipping operated.

In this way, a tensile force or a drive torque can be provided for the traction compensation of the electric machine at the output, which is greater than the electrically provided by the electric machine drive torque. As a result, the sportiness of a circuit with traction interruption of the internal combustion engine can be increased.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. An embodiment of the invention will be described, without being limited thereto, with reference to the drawing. Showing:

1 a block diagram of a drive train to illustrate the method according to the invention; and

2 Diagrams for further clarification of the method according to the invention.

The present invention relates to a method for operating a drive train of a hybrid drive. 1 shows an example of such a drive train of a hybrid drive whose output 1 of two driven axles 2 and 6 provided.

On a first, driven axle 2 the downforce 1 is powered by an internal combustion engine 3 provided a drive torque or a tensile force, wherein between the output 1 namely the driven axle 2 , and the internal combustion engine 3 an automated manual transmission 4 is switched. Between the automated manual transmission 4 and the internal combustion engine 3 can according to 1 continue a clutch 5 be switched. In the automated manual transmission 4 Circuit interrupts the engine 3 at the output 1 provided traction.

In addition to the first, driven axle 2 has the downforce 1 via a second, driven axle 6 on which an electric machine 7 can provide a drive torque or a tensile force. Between the electric machine 7 and the driven axle 6 of the drive 1 is in 1 a constant translation 8th switched, in addition, between the electric machine 7 and the constant translation 8th a friction clutch 9 is switched.

In contrast to the embodiment shown, it is possible that both the internal combustion engine 3 as well as the electric machine 7 acting on a common, driven axle of the output. So it is possible, for example, that the electric machine 7 at the output end of the automated transmission 4 is arranged and via a friction clutch on the driven axle 2 the downforce 1 attacks.

As already stated, are in the automated manual transmission 4 of the powertrain circuits interrupting the engine 3 at the output 1 provided traction, for this purpose, first in a first phase of the internal combustion engine 3 at the output 1 provided traction removed, then a second phase, the actual circuit running and subsequently in a third phase of the internal combustion engine 3 at the output 1 provided traction is rebuilt. Order now in the execution of the circuit in the automated manual transmission 4 the traction interruption of the internal combustion engine 3 at the output 1 At least partially offset, according to the invention, a function is used, taking advantage of a mechanical flywheel torque of the electric machine 7 the traction interruption of the internal combustion engine 3 at least partially compensates for that between the electric machine 7 and the downforce 1 switched friction clutch 9 defined slipping operated.

This can be done on the electric machine 7 a drive torque at the output 1 and to provide a tensile force thereon greater than that of the electric machine 7 purely electrically deployable traction. As a result, it is ultimately possible, a greater compensation for the interruption of traction of the internal combustion engine 3 at the output 1 provide.

Further details of the method according to the invention for operating a drive train are described below with reference to FIG 2 described, in 2 are shown in the case of a circuit design at constant speed and constant tensile force several temporal curves, namely a time course of a speed n7 of the electric machine 7 , A time course of a driven-side rotational speed n9 of the friction clutch 9 , a time course of one of the electric machine 7 electrically deliverable torque M7, a time course of one of the friction clutch 9 transmitted torque M9, a time course of a taking advantage of the function of the invention on the axis 6 the downforce 1 from the electric machine 7 provided drive torque M6 and a time course of one of the internal combustion engine 3 on the driven axle 2 the output provided drive torque M2. That at the output 2 applied total drive torque corresponds to the sum of the drive torque M2 and M6.

2 can be seen that between the times t2 and t6 in the automated manual transmission 4 a circuit with interruption of the internal combustion engine 3 on the axis 2 provided traction, wherein in the first phase defined by the times t2 and t3 one of the internal combustion engine 3 driven axle 2 the output provided drive torque M2 and thus a corresponding tensile force is reduced in a second phase defined by the times t3 and t4 the circuit is executed and subsequently in a defined by the times t4 and t6 third phase after execution of the actual gear change from the internal combustion engine 3 on the driven axle 2 the downforce 1 provided traction or the corresponding drive torque M2 is increased again.

The inventive function, the at least partially balancing the interruption of traction of the internal combustion engine 3 and thus the compensation of the degradation of the internal combustion engine 3 at the output 1 provided drive torque M2 is, according to 2 Triggered at time t1, the release of this function can be done, for example, by a shift or a gear change in the automated manual transmission 4 initiated on the driver side or detected on the control side. The control-side detection of an upcoming circuit is typically carried out in a transmission control device under evaluation a driver's request, a speed of the engine 3 and a driven side speed of the automated transmission 4 , Details by means of which an imminent circuit can be recognized on the control side are familiar to the person mentioned here.

Then, when the function according to the invention for at least partially balancing the traction interruption of the internal combustion engine 3 is triggered, which in the embodiment shown the 2 is done at the time t1, is first at the between the electric machine 7 and the downforce 1 switched friction clutch 9 a defined speed difference between the speed n7 of the electric machine 7 and the output side rotational speed n9 of the friction clutch 9 constructed according to what 2 from the electric machine 7 which is provided by the same electrically maximally available torque M7 and what the friction clutch 9 is closed to the Anlegpunkt or is held on the Anlegpunkt, so that of the friction clutch 9 just no moment M9 is transmitted.

Then, if the speed difference between the speed n7 of the electric machine 7 and the output side rotational speed n9 of the friction clutch 9 reaches or exceeds a speed limit, which in the embodiment of the 2 at time t2, the execution of the circuit is subsequently started. In other words, the degradation of the internal combustion engine 3 at the output 1 provided traction or with the degradation of the internal combustion engine 3 at the output 1 provided drive torque M2 waited until the speed difference between the speed n7 of the electric machine 7 and the output side rotational speed n9 of the friction clutch 9 reaches or exceeds the first limit. This is, as already stated, in 2 at time t2 the case.

Subsequent to the time t2, the circuit is interrupted by the engine 3 at the output 1 provided traction or interruption of the same at the output 1 provided drive torque M2, which for this purpose, starting from the time t2 first that of the internal combustion engine 3 provided drive torque M2 or the provided tensile force is reduced.

According to 2 is also starting with the time t2, ie with reaching or exceeding the speed limit for the speed difference between the speed n7 of the electric machine 7 below the output side speed n9 of the friction clutch 9 , the friction clutch 9 controlled so that the same is initially so much slipping closed that of the friction clutch 9 transmitted torque M9 is increased, namely until it reaches or exceeds a torque limit at time t3. The increase of the friction clutch 9 transmitted Moments M9 is preferably carried out so that the resulting structure of the moment M6 at the output 1 just compensates for the momentum M2.

According to 2 can in this case of the friction clutch 9 a torque M9 be transmitted, which is greater than the electrically available torque M7, since previously between the times t1 and t2 by the defined slip on the friction clutch 9 the flywheel of the electric machine 7 was charged. This mechanical flywheel torque of the electric machine 7 is used between times t2 and t4 to over the friction clutch 9 at the output 1 , namely in 1 on the driven axle 6 to provide the moment M6 or a corresponding tractive force, which the traction interruption of the internal combustion engine 3 or the interruption of the corresponding moment M2 compensates.

The torque limit for that of the friction clutch 9 transmitted torque M9 is determined so that by the electric machine 7 provided drive torque M6 maximum that of the internal combustion engine 3 before and after the circuit execution provided drive torque M2 corresponds.

Then, if that from the friction clutch 9 transmitted torque M9 reaches or exceeds the torque limit, which in the embodiment of the 2 At time t3, the following will be from the friction clutch 9 transmitted torque M9 is not further increased, but rather held so constant and then reduced so starting from the time t4, so that when at time t5, the friction clutch 9 no longer slips, that of the friction clutch 9 transmitted torque M9 in about that of the electric machine 7 electrically maximum torque M7 equals. This allows a particularly convenient circuit design with traction compensation.

The reduction of the friction clutch 9 transmitted torque M9 is preferably such that the sum of the drive torque M2 and M6, the output 1 abut, remains approximately constant.

At time t5, there is the friction clutch 9 no slip, so then the speed n7 of the electric machine 7 the output side rotational speed n9 of the friction clutch 9 equivalent. At this time, this corresponds to the friction clutch 9 transmittable moment M9 that of the electric machine 7 electrically maximum deployable torque M7.

From the time t5 that of the friction clutch 9 transmitted torque M9 according to 2 kept constant or alternatively raised again to make sure that at the friction clutch 9 no slip occurs again.

Starting with the time t5 that is from the electric machine 7 provided moment M7 lowered, so that the sum of the drive torques M2 and M6, which at the output 1 abut, remains approximately constant.

At time t5, this is sufficient for the electrical machine 7 electrically maximum deployable moment M7 off, to alone the traction interruption of the internal combustion engine 3 compensate, so from this point on the flywheel torque of the electric machine 7 is no longer needed for traction compensation.

At the time t6, the circuit execution and the tension compensation is completed altogether.

In the illustrated embodiment of the 2 it was assumed that a driver's request remains constant. In the event that a driver's request changes, that of the friction clutch 9 between the times t2 and t5 transmitted torque M9 tracking the driver's request. For example, if the driver goes off the gas, then between the times t2 and t5 of the friction clutch 9 transmitted torque M9 reduced accordingly.

As already stated, preferably the execution of a circuit is delayed until, until the time t2 a sufficient speed difference between the speed n7 of the electric machine 7 and the output side rotational speed n9 of the friction clutch 9 was built up until the flywheel of the electric machine 7 was sufficiently charged.

Should such a delay of a circuit execution, for example, by an inadmissible exceeding or falling below the speed of the internal combustion engine 3 can not be delayed until this speed difference, it is already previously started with the circuit execution, in which case then the compensation of the interruption of traction, via the above-mentioned control of the friction clutch 9 is ensured, is reduced, so that at the time t5 in turn, the already mentioned synchronization conditions are met.

The speed limit, which is to be reached or exceeded at the time t2, can be calculated, namely depending on the time required to execute the circuit, ie depending on the times t6 and t2 or t4 and t3, depending on the required course of the of friction clutch 9 Moments M9 to be transmitted from the electric machine 7 maximum moment M7 and the mass inertia of the flywheel of the electric machine 7 ,

LIST OF REFERENCE NUMBERS

1

output

2

driven axle

3

internal combustion engine

4

transmission

5

clutch

6

driven axle

7

electric machine

8th

constant translation

9

clutch

Claims (9)

A method of operating a powertrain of a motor vehicle with a drive unit comprising at least one electric machine and an internal combustion engine, wherein the internal combustion engine is coupled to an output via an automated transmission, wherein in the automated manual transmission interrupting provided by the internal combustion engine at the output tractive power such circuits be that first degraded in a first phase provided by the engine to the output tractive force, then executed in a second phase after breaking the tension the circuit and then in a third phase after execution of the actual circuit the provided by the engine at the output traction again is constructed, characterized in that when running the circuit, the traction interruption of the internal combustion engine by a function using a mechanical momentum moment s of the electric machine of the drive unit is at least partially offset by the fact that a switched between the electric machine of the drive unit and the output friction clutch is operated slipping hatched. A method according to claim 1, characterized in that the function for at least partially balancing the interruption of traction of the internal combustion engine is triggered when a circuit is initiated on the driver side. A method according to claim 1, characterized in that the function for at least partially balancing the interruption of traction of the internal combustion engine is triggered when an impending circuit is detected on the control side. Method according to one of claims 1 to 3, characterized in that when the function for at least partially balancing the traction interruption of the internal combustion engine is triggered, first at the between the electric machine of the drive unit and the output connected friction clutch a defined speed difference between the speed of electrical machine and the output side speed of the friction clutch is constructed, wherein the first phase of the circuit design, namely the reduction of the combustion engine provided at the output tractive force is delayed until this speed difference reaches or exceeds a speed limit. A method according to claim 4, characterized in that when this speed difference reaches or exceeds the speed limit, the friction clutch is controlled such that the same is initially as slipping closed until the transmitted from the friction clutch and provided by utilizing the flywheel torque at the output torque reaches or exceeds a moment limit. A method according to claim 5, characterized in that subsequent to the increase of the torque transmitted by the friction clutch up to the torque limit, the friction clutch is controlled so that initially held by the same torque is kept constant and anschleißend again reduced, so that when the friction clutch no longer slips, which corresponds to the torque transferable by the friction clutch in about the maximum electrical torque from the electric machine. A method according to claim 6, characterized in that, when the friction clutch is no longer slipping, the moment electrically provided by the electric machine is subsequently reduced. Method according to one of claims 4 to 7, characterized in that, if the first phase of the circuit execution can not be delayed, the compensation of the traction interruption is reduced. A method according to claim 8, characterized in that the compensation of the interruption of traction is reduced such that when the friction clutch is no longer slipping, the torque transmitted by the friction clutch corresponds approximately to the electrical maximum of the electric machine deployable moment.

Images