DE102008032769A1 - Method for controlling recuperation process in motor vehicle, involves controlling amount of torque within another time interval, which lies between switching operations, using interconnection relationship - Google Patents

Abstract

The method involves charging a gearbox input shaft (14) in series of brake torque requirement (F) with a generator torque (MG) of an electrical machine (12). An amount of the torque is controlled depending on the strength of the torque requirement. The amount of the torque is controlled within a time interval, which lies around a switching operation of a shift gearbox (16), using an interconnection relationship (28). The amount of the torque is controlled within another time interval, which lies between the switching operations, using another interconnection relationship (30).

Description

Field of the invention

The The invention relates to a method for controlling a recuperation process in a motor vehicle with an internal combustion engine and one both motorized or regenerative electric machine, in torque-additive manner to a transmission input shaft of a gearbox act, the transmission output shaft with wheels of the motor vehicle coupled, wherein the transmission input shaft as a result of a braking torque request subjected to a generator torque of the electric machine and the amount of the generator torque depending on the strength of the braking torque request and on the Gangeinstellung is controlled.

State of the art

Such methods are known from the DE 10 2004 025 830 A1 , This document describes the control of a recuperation process, ie the recovery of kinetic energy of a motor vehicle in a so-called parallel hybrid. In the parallel hybrid two separately controllable drive machines are provided, of which at least one is an electric machine; the second prime mover is typically an internal combustion engine. Both drive machines act indirectly or directly on the transmission input shaft of a gearbox, with their acting on the transmission input shaft moments add up. As a manual transmission is any known form of a gearbox, in particular manual or automated manual, automatic multi-step or direct gearbox in question.

at the known method, the electric machine for recuperation subjected to a generator torque. This means that the electric Machine is controlled so that it works in generator mode. In this case, the rotor of the electric machine on the Transmission input shaft driven; the regenerated energy is typically in an energy storage, such as an accumulator, passed. The transmission input shaft is doing subjected to a braking or negative drive torque. The Vehicle, via its manual transmission and transmission output shaft the transmission input shaft is coupled to the wheels, This slows down. In the known method is not the entire braking energy generated by the generator torque. Rather, in the braking torque request, in particular after exceeding a Threshold or at the latest after reaching a maximum Generator torque also activates a standard vehicle brake, the kinetic energy of the vehicle via braking or drums converts into heat energy. The braking torque request is typically done by the driver by means of actuation a brake pedal. However, there are also additional or supportive, automated braking requirements through Brake assistants or the like known.

in the In terms of fuel economy, it is beneficial to one as large a proportion of the braking power over to generate the generator torque. However, it must meet the operating requirements the electric machine or the internal combustion engine and the Safety and predictability of the braking process become. Here, in particular, the currently set translation plays the manual transmission plays a big role. In the mentioned Reference is therefore proposed, the generator torque in about to control linearly with the strength of the brake torque request, however, this is a minimum brake torque request strength assigned offset torque is dependent on the current Gear adjustment, d. H. from the current translation.

adversely in the known method, torque mismatches are between the transmission input shaft and the transmission output shaft due to of translation jumps during switching operations may occur. Especially with automatic transmissions switched the transmission during braking according to the down driving speed. Every time you switch the translation increases, here as the torque ratio of the transmission output shaft the transmission input shaft should be defined, essentially leaps and bounds. Of course, the translation change takes place actually steady due to the slip operation of the clutches; however, the resulting translation ramp is particular very steep for dual-clutch or direct-shift transmissions, so that talked about an essentially erratic translation change can be. The translation change leads to a torque jump on the wheels of the motor vehicle, which can be perceived by the driver as comfort-reducing.

task

It the object of the present invention is a recuperation method to improve such that the ride comfort during switching operations during the braking process is improved.

Presentation of the invention

This object is achieved in conjunction with the features of the preamble of claim 1, characterized in that the amount of the generator-type tes within first time intervals, which are gearshifts of the gearbox, by means of a first dependency relationship and within second time intervals, which are intermediate the gearshifts, are controlled by means of a second dependency relationship.

It is the basic idea of the present invention, the control of Generator torque on the one hand during a switching operation and on the other hand during the periods between Switching operations as separate events with consider separate tax characteristics. For each of the Both processes can thus separate characteristics independently from each other on the concrete requirements of the respective process be optimized. Between the switching operations, the Dependence of the generator torque on the brake torque request strength with regard to a maximum recuperation of kinetic energy be optimized. During the switching operations, however may be the optimization in terms of avoidance of torque mismatch between transmission input shaft and transmission output shaft and thus in Be optimized for comfort. During this Phases may not be the maximum recuperation power realized.

The This invention avoids the realized in the prior art Compromise, neither in terms of maximizing recuperation performance can still be regarded as optimal on the comfort.

Especially favorable embodiments are the subject of dependent claims.

Prefers the dependency relationships become separate maps in a memory of an electric control unit Machine or hybrid drive. Unlike pure Characteristics gives the deposit of maps the possibility Dependencies of the generator torque of several parameters, in particular the braking torque request strength and the currently set translation.

Prefers is the amount of the generator torque according to the first dependency relationship so controlled that one through generated the ratio change of the shift Torque mismatch of transmission output shaft and transmission input shaft is at least partially compensated. This means that the generator torque during the shift of the gear change follows. At the essentially erratic increase in the translation during a switching operation, the generator torque decreases similarly leaps and bounds, so that the translation change not in a sudden moment change on the wheels effect. Rather, the moment change is due to change the generator torque input side of the gearbox intercepted. Subsequent to the switching process, the second dependency relationship, the prefers a substantially linear relationship of the amount of Generator torque of the strength of the braking torque request is to be passed over.

Prefers follows the amount of generator torque during a transition from the first (or second) dependency relationship as Initial relationship to the second (or first) dependency relationship as target relationship one between the currently set amount and the one to be set according to the target relationship Amount interpolated amount. In other words, that amount becomes the generator torque determined according to the currently not active dependency relationship set would have to be. Subsequently, an example linear interpolation between the currently set generator torque amount and the generator torque amount to be set after the dependency change interpolated. The transition from the initial relationship to Target relationship can then be within a given, on the one hand as possible short and on the other hand for a comfortable driving behavior sufficiently long period of time. The time span of this transition can in a development of the invention of the current gear setting be dependent.

As mentioned, are the dependency relationships of Generator torque of the brake request strength preferred stored in maps, d. H. they are preferably multi-parameter dependencies. In a further development of the invention, it is provided that the measure in which the torque mismatch according to the first Dependency relationship during the switching process is compensated by the current gear setting or translation is dependent. This training contributes to the fact Invoice that a torque mismatch, especially at small corridors, d. H. high translations, comfort has a reducing effect. At low translations is the Influence on the comfort lower. In these cases can therefore at the expense of an incomplete compensation of the torque mismatch a higher recuperation power can be realized. In A preferred embodiment is the switching operation even by modulation of the generator torque wheel torque neutral carried out; the legal deviation from moment neutrality is set by a factor, a characteristic or a map (at least gear or translation dependent).

The second dependency relationship can also be a dependency on the current transition position or translation. In particular, it is provided in a further development of the invention that an offset torque associated with a minimum braking torque request intensity is dependent on the current gear setting.

Further Features and advantages will be apparent from the following specific Description and the drawings.

It demonstrate:

1 a schematic representation of the prime movers of a parallel hybrid,

2 three graphs illustrating the method according to the invention.

1 shows in a highly simplified schematic representation of the front part of the drive train of a parallel hybrid. This includes an internal combustion engine 10 and a downstream electric machine 12 , Both drive machines 10 . 12 act in torque additively on a shaft that is connected to the transmission input shaft 14 a gearbox 16 by means of a separating clutch 18 can be coupled. With the help of the manual transmission 16 are different translations feasible, here as the ratio of the torque at the transmission input shaft 14 and the transmission output shaft 20 are defined. The transmission output shaft 20 is connected via other drive train elements, such as differentials, with the wheels of the vehicle. In the embodiment shown, the internal combustion engine 10 by means of an additional, in 2 dashed line separating clutch 22 separable from the electric machine. However, such a second separating clutch is not absolutely necessary. The electric machine 12 is with an energy storage 24 from which it draws energy during motor operation and in which it feeds energy during regenerative operation. The operation of the electric machine 12 is by means of a control unit 26 controlled. In the control unit are at least two maps 28 . 30 for controlling a generator torque MG of the electric machine 12 stored during a recuperation process. In 1 are shown in a first map several characteristics that the dependence of the generator torque MG of the transmission 16 represented translated translation i. The second in 1 The map shown shows several characteristics, each representing a dependence of the generator torque MG of a magnitude of a braking torque request F. The braking torque request F can be represented, for example, by the sensory detected position of a brake pedal or the position of the lifting rod of a brake cylinder or in a similar manner. Note that the maps are shown purely schematically and in particular the dependencies of the characteristics of the translation i or the braking torque request F represent no exclusive dependencies. Rather, it may be in a practical embodiment that both maps 28 . 30 multi-parameter dependencies of the generator torque MG include, in both maps 28 . 30 Dependencies are stored by the same parameters; only the form of dependence on the individual parameters can be found in the maps 28 . 30 to be different. In the 1 selected representation is intended to indicate that in the first map 28 a particularly strong dependence on the current translation is selected, ie that the generator torque MG with active first map 28 Essentially, translation changes follow. The second map 30 On the other hand, it is intended to illustrate that, when activated, the generator torque MG essentially follows changes in the brake torque request F in order to maximize the recuperation efficiency.

According to the invention it is provided that the different maps 28 . 30 are active at different times. Between the activity phases of the two maps 28 . 30 the magnitude curve of the generator torque MG can follow a curve interpolated between the maps. Alternatively, one or more maps may be defined that are active during the transition phases between the first and second maps.

2 shows three graphs that illustrate the operation of the method according to the invention. In 2a is a concrete case of a braking torque request F over the time t shown. The graph essentially corresponds to a horizontal line, ie a constant braking torque request, for example a constant position of a brake pedal. Only in the area of the deflections 32 and 34 the braking torque request is briefly reduced ( 32 ) and increases ( 34 ).

Such a brake torque request results in a continuous deceleration of the vehicle. In particular, in an automatic transmission or direct shift transmission, as in 2 B represented, the ratio i of the gearbox 16 gradually increased with the falling vehicle speed. The translation increase takes place in each case within the intervals T1. The length of the intervals T1 is essentially due to the control of the slip phase of the clutches of the transmission 16 certainly. Outside the switching periods T1, intervals T2 of constant transmission are shown. Between the switching phases T1 and the phases T2 constant translation, a transition phase T3 is shown in each case, whose meaning in connection with the following explanation from 2c becomes clearer. 2c shows the course of the generator torque according to the present invention in the subfigures a and b of 2 given situation. Note that the generator torque MG is shown here as a negative value.

It can clearly be seen that during the switching phases T1, the magnitude of the generator torque behaves inversely to the transmission, ie it falls with the increase in the ratio. The generator torque "follows" the ratio jump during the switching process. This is made possible by the fact that during the phases T1, the first map 28 is activated. By the jump of the generator torque corresponding to the ratio jump, a torque jump on the transmission output shaft 20 , which would feel comfort mitigated, caught on the input side. On the other hand, during the phases of constant gear ratio T2, the generator torque is set to a high value, which corresponds to optimization with regard to maximum efficiency of recuperation, taking into account the operating requirements of the engine and the safety of the braking operation. The course of the generator torque during the phases T2 is through the second map 30 predetermined, which activates during the phases T2. is. Between the phases T1, in which the generator torque substantially follows the translation, and the phases T2 constant generator torque are the transition phases T3, in which of the activation of the first map 28 is superimposed to activate the second map 30 , This transition should not be made abruptly for reasons of comfort. Rather, as in 2c represented, the amount of the generator torque in the transition of a interpolated between the two maps course line follow.

Of course, in any phase of operation, regardless of the actual activation of a map, the vehicle must be able to respond to any changes in the brake torque request by the driver or an automated device such as a brake assist. This is how the deflection takes place 32 the braking torque request F during an interval T2. The generator torque follows the increase 32 the braking torque request immediately. Also the reduction 34 the brake torque request is immediately followed by the generator torque, although the latter occurs at least in part during a transition interval T3 in which the magnitude of the generator torque should always follow an interpolated transition. Analog should preferably be possible during the switching intervals T1. Such a responsiveness to changes in the braking torque request can be implemented, for example, by defining at least one additive dependency on the instantaneous braking torque request in each characteristic map. Alternatively, when changing the brake torque request can be abruptly blended to another map.

Naturally put those discussed in the special description and in the Figures shown embodiments only illustrative embodiments The expert is in the light of the local Revelation a wide range of possible variations given by. In particular, the dependencies in the individual maps the concrete intended application be adjusted. Also the length of the individual intervals, In particular, the transition intervals may vary to the individual case adapted and / or of other parameters, such as the adjusted translation. Of course, the number of in the control unit The electric machine stored maps not through the here exemplarily discussed numbers limited.

10

internal combustion engine

12

electrical machine

14

Transmission input shaft

16

transmission

18

separating clutch

20

Transmission output shaft

22

separating clutch

24

Battery / energy storage

26

control unit

28

first map

30

second map

32

deflection Braking torque request

34

deflection Braking torque request

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004025830 A1 [0002]

Claims (8)

Method for controlling a recuperation process in a motor vehicle having an internal combustion engine ( 10 ) and an electrically as well as generically operable electric machine ( 12 ) in torque-sensitive manner to a transmission input shaft ( 14 ) of a manual transmission ( 16 ) whose transmission output shaft ( 20 ) is coupled to wheels of the motor vehicle, wherein the transmission input shaft ( 14 ) as a result of a braking torque request (F) with a generator torque (MG) of the electric machine ( 12 ) and the magnitude of the generator torque (MG) is controlled as a function of the magnitude of the braking torque request (F) and of the gear setting (i), characterized in that the magnitude of the generator torque (MG) is within first time intervals (T1), the switching operations of the gearbox ( 16 ), by means of a first dependency relationship ( 28 ) and within second time intervals (T2) lying between the switching operations by means of a second dependency relationship ( 30 ) is controlled. A method according to claim 1, characterized in that the dependency relationships as separate maps ( 28 . 30 ) in a memory of a control unit ( 26 ) are deposited. Method according to one of claims 1 to 2, characterized in that the amount of the generator torque (MG) according to the first dependency relationship ( 28 ) is controlled so that a generated by the ratio change of the respective switching operation torque mismatch of transmission output shaft ( 20 ) and transmission input shaft ( 14 ) is at least partially compensated. Method according to claim 3, characterized characterized in that the extent to which the torque mismatch is compensated, depending on the current gear setting (i) is. Method according to one of the preceding claims, characterized in that the second dependency relationship ( 30 ) is a linear dependence of the amount of generator torque (MG) on the magnitude of the brake torque request. Method according to Claim 6, characterized that is a minimum braking torque request strength assigned offset torque depending on the current gear setting is. Method according to one of the preceding claims, characterized in that the amount of the generator torque (MG) during a transition from the first or second dependency relationship (MG) 28 ; 30 ) as the initial relationship to the second or first dependency relationship ( 30 ; 28 ) follows as a target relationship during a third time interval (T3) an amount interpolated between the currently set amount and the amount to be set according to the target relationship. Method according to claim 8, characterized in that that the period (T3) of the transition from the current Gangeeinstellung (i) is dependent.