DE102007055826A1 - Method and device for operating a hybrid drive of a vehicle - Google Patents

Abstract

The invention relates to a method and a device for operating a hybrid drive (1) of a vehicle, having a parallel hybrid drive train (2) comprising an internal combustion engine (3), at least one electric machine (5), at least one power flow direction between the internal combustion engine (3 ) and the electric machine (5) arranged switching element (4), a transmission (7) and an output (25), in which for starting the internal combustion engine (3) by means of the electric machine (5), the switching element (4) is closed. In order to keep a period of traction with a power interruption with a start of the internal combustion engine (3) via the electric machine (5) and its coupling to the drive train (2) as short as possible and still to ensure a high level of ride comfort, a starting speed of the engine (3) directly is controlled to a predicted target transmission input speed of a following ratio, wherein the beginning of a firing of the internal combustion engine (3) is optionally correlated with the speed control.

Description

The The invention relates to a method and an apparatus for operation a hybrid vehicle according to the preamble of Patent claim 1 or claim 10.

hybrid power take-offs gain in vehicle manufacturing due to their potential for reduction of pollutant emissions and energy consumption are becoming increasingly important. Such vehicles have various types of power sources, in particular combinations of combustion and electric motors on the one hand the range and performance advantages of internal combustion engines and on the other hand, the flexible uses the electric machines as a sole or auxiliary drive source or as a starter generator and as a generator for power generation and recuperation can use.

from Market hybrid drive trains are required, the possible without additional space requirements, if possible low complexity and at low cost and design effort can be implemented in vehicles. It will be basically two hybrid topologies, the series hybrid and the parallel hybrid distinguished. Such arrangements are already known and will constantly evolving.

At the Series hybrid, the prime movers are connected in series. In this case, the internal combustion engine, for example a diesel engine, as a drive for a generator, an electric machine fed. The vehicle is thus exclusively over the electric machine powered. The internal combustion engine is however, decoupled from the drive wheels and therefore can constantly in a single operating point, d. H. at a certain torque and constant speed are operated. This drive concept is suitable, for example, for buses in urban short-distance traffic, preferably an operating point in which the efficiency of the internal combustion engine as possible is high and at the same time pollutant emissions, fuel consumption and noise in a favorable range lie, is set. Unfavorable affects the series hybrid on the other hand, that the efficiency of the drive due to the mechanical-electrical Multiple conversion is restricted.

In contrast, provide parallel hybrid powertrains by a reference the power flow parallel arrangement of the drive train assemblies in addition to the superposition the drive torque, so a mixed drive, also the possibility the control with purely internal combustion engine drive or pure electromotive, in short called electrical, drive. Functional can in the parallel hybrid of the internal combustion engine by respective Burden or support by means of one or more operated electrical machines largely at optimal torque so that the maximum efficiency of the internal combustion engine can be used effectively. By the electrical support the internal combustion engine reduces on average the fuel consumption. As with short-term increased power requirements in the so-called boost operation, for example, in overtaking, a Summation of the drive power is possible, the internal combustion engine almost no loss of performance and ride comfort of the vehicle comparatively smaller, and designed to save weight and space which additionally reduces emissions and cost effective. The electric machine can also as integrated starter generator (ISG) to start the combustion engine via a clutch act. Furthermore, the electric machine in the generator Operation to charge an electrical energy storage and serve be used for recuperation in braking mode. As a transmission for varying the ratio of the drive of the driven axles In principle, all forms of vehicle transmissions come into consideration.

at a parallel hybrid drive can be dependent in practical driving from a respective hybrid operating strategy, the driving form of the vehicle between internal combustion engine drive, electric motor drive and mixed drive frequently. In purely electric Driving operation, the electric machine is connected to the output while the combustion engine via a separating element from the drive train is decoupled. Should the electric machine in this situation as integrated starter generator to start the engine, so the internal combustion engine via the separating element again switched on. Basically, such an engine start both during a translation of the Transmission as well as outside of gear shift operations and both with and without interruption of traction. Various suitable start modes are in a further patent application the applicant described.

The changing connection of the electric machine and the internal combustion engine in the drive train in the parallel hybrid is usually realized via couplings. In this case, a distinction is made between two-clutch arrangements (2K) and one-clutch arrangements (1K), in which case the electric machine can function as integrated starter generator (2K-ISG or 1K-ISG arrangement) in both concepts. In a 2K ISG powertrain, such as from the US 2005 022 1947 A1 known, is the combustion motor via a first coupling with the electric machine connectable. The electric machine in turn can be coupled via a separate second clutch with a vehicle transmission. In a 1K ISG powertrain, such as from the DE 10 2005 051 382 A1 known, however, eliminates a second separate coupling between the electric machine and the transmission or the output. The electric machine can then be directly connected to a transmission input.

The Function of an optional second clutch between the electric machine and the output can, as far as provided for the respective Antriebskon concept or is required, including any existing ones internal gear clutches and / or switching brakes, as for example are installed in automatic gearboxes, or upstream of a gearbox Converter lockup clutch adopted become.

The Starts the internal combustion engine by means of the electric machine comes in the hybrid drive a special meaning, because on the one hand for the driving comfort and on the other hand for the driving dynamics decisive are. They also play for the economy and the efficiency of the hybrid drive an important role. It can a switching strategy and a hybrid operating strategy correlated in such a way be that relatively often a switching request with a Engine start request coincides in time, where ever according to drive concept and gearbox design, the switching process with a Traction interruption can be linked.

The start of the internal combustion engine at a ratio change during electric drive or during a starting process, such as from DE 10 2005 007 966 A1 and the one already mentioned DE 10 2005 051 382 A1 be known, performed by the transmission first, optionally with a torque reduction required for this at the transmission input, switched to a neutral position, then closed a clutch between the engine and the electric motor and then the internal combustion engine is started by means of the electric machine. It is also possible that, in equivalence to a transmission neutral position, to start the internal combustion engine, if present, a arranged between the electric machine and the transmission second clutch is opened. Due to the neutral position of the transmission or the separation of the electric machine from the transmission is at start in traction interrupted circuit thus in any case the engine completely decoupled from the output of the transmission at least almost completely at least during startup so that engine-induced shock loads in the drive train can be largely avoided.

A usually necessary synchronization of the transmission input a connection speed of the sequence to be inserted can be alone after the engine starts with the clutch open by means of the electric machine or with the clutch in the composite done with the internal combustion engine. Is then first a purely electric drive desired by the electric machine, for example for a start-up procedure during a start / stop operation, so the clutch can be completely returned to the engine opened and by means of a speed control of the electric machine a Transmission input shaft to a synchronous speed of einzulegenden Ganges, for example, the first gear, be regulated while the internal combustion engine is operated without load during idling.

Should the internal combustion engine will be switched on later, so will First, the speed of the running internal combustion engine the current speed (above idle speed) at the transmission input adjusted and then closed the clutch. Should However, the internal combustion engine are switched directly, so is an instant correlated speed control of the circulating in the block Drive units required to synchronize the transmission input. Only after synchronization, the target gear or the Target gear stage inserted easily and the pulling power produced or be restored.

By the traction interruption runs the starting process of the internal combustion engine while the gear change while largely without shock loads from, which is perceived by the driver as pleasant. Disadvantageous However, that is the period of the start request or shift request until the recovery of traction especially then relatively is great when the internal combustion engine is directly to the drive available hen, whereby the advantage of the better Fahrkomforts with such traction-interrupted engine starts a not inconsiderable impairment of the driving dynamics precludes.

In front In this background, the invention is based on the object Method and device for operating a hybrid drive a vehicle with an internal combustion engine and an electric machine Specify as drive units, in which the period of a traction Switching operation at a start of the internal combustion engine by means of Electric machine and its coupling to the drive train as short as possible is, and yet ensure a high level of ride comfort.

The solution of this problem arises from the features of the independent claims, while advantageous embodiments and weitererbil tions of the invention can be removed from the dependent claims.

Of the Invention is based on the finding that in a parallel hybrid drive at the start of the engine by means of an electric machine in a circuit with a traction interruption, by a direct control of the starting speed of the engine to a transmission input speed of the subsequent course, the period from the beginning of the traction interruption shortened to the completion of the circuit with coupling of the internal combustion engine can be.

According to the Features of claim 1, the invention is based on a method for operating a hybrid drive of a vehicle with a parallel hybrid powertrain, comprising an internal combustion engine, at least one electric machine, at least one in power flow direction between the internal combustion engine and the electric machine arranged switching element, a transmission and an output, in which for starting the internal combustion engine by means of the electric machine, the switching element is closed.

Under a switching element for connecting the internal combustion engine and electric machine are understood all types of automatically controllable actuators, about the internal combustion engine and the electric machine can be coupled together. This can be, for example, an electro-hydraulic or electro-pneumatic operable frictional starting and separating clutch be.

to Solving the problem, the invention provides that during a starting process of the internal combustion engine during a traction interruption in a switching operation of the transmission a starting speed of the internal combustion engine directly to a pre-calculated Target transmission input speed of a following ratio regulated is, wherein the beginning of a firing of the internal combustion engine optionally is correlated with the speed control.

at a zugkraftuptbrochenen switching operation is basically Also included is the case where an origin gear (inlaid Gang) and a target gear stage (gear to be engaged) are equal, where although a circuit but no translation change he follows. Similarly, a circuit is as traction interrupted Switching to understand, in which a starting gear while stationary Vehicle is engaged and the target transmission input speed of a Following ratio the transmission input speed of the starting gear is.

Under an engine firing will be a fuel injection with a following spark ignition or autoignition of the understood formed air-fuel mixture in the internal combustion engine, wherein a start of the engine firing is the first injection timing is.

in principle the invention is in all types of vehicles with such Can be used parallel hybrid drive trains.

Farther The object is achieved by a device for carrying out solved the method. Accordingly, the invention continues from a device for operating a hybrid drive of a A parallel hybrid powertrain vehicle comprising Internal combustion engine, at least one electric machine, at least one in the power flow direction between the engine and the electric machine arranged switching element, by means of which the internal combustion engine with the electric machine is positively connected, a transmission and a downforce. In addition, control means are provided, with which at a start of the internal combustion engine by means of the electric machine during a traction interruption in a switching operation of the transmission a starting speed of the internal combustion engine directly to a pre-calculated Target transmission input speed of a following ratio controllable and the beginning of a firing of the internal combustion engine optionally can be correlated with the speed control.

By the process sequence according to the invention is a Shortening of the starting and Ankoppelvorgangs the internal combustion engine enabled in circuits with parallel hybrid drive. This is essentially achieved by the internal combustion engine when raising its crankshaft speed directly to the new Target transmission input speed is accelerated, which is after Completion of the circuit according to the new translation established. Thus, an additional control step for setting the already running internal combustion engine on the required speed saved, resulting in the required Time to synchronize the transmission input to the speed the subsequent course and thus the duration for the preparation of the active compound of the internal combustion engine via the transmission and the output shortened with the driven wheels of the vehicle.

The to be determined in advance respective new target transmission input speed in a switching operation can be relatively easy from the provided Following translation and from the current output speed or the driving speed or derived therefrom sizes be determined.

In a first inventive sequence can be advantageously provided that the internal combustion engine by means of the electric machine at ge closed switching element, for example, a frictional start-up and decoupling, is raised to the target transmission input speed, wherein the engine fire is initiated upon reaching or approaching reaching the target transmission input speed.

Therefore In this process, the injection timing can be freely selected. In this case, the internal combustion engine during the traction interruption in a circuit, preferably by a swing start or a direct start, speed-controlled by the electric machine brought the target transmission input speed, but initially without the internal combustion engine being fired. Just before or when reaching the target speed of the internal combustion engine is fired. Thus, the internal combustion engine is started immediately at the speed, necessary to insert the target gear at the transmission input is why the synchronization of the transmission input immediately with the engine started.

at a gear change during an electric drive of the Vehicle, a swing start is particularly advantageous as a start mode, because the electric machine already drives the vehicle at a certain speed drives. To start the engine, first the clutch open and at the electric machine the target transmission input speed set or the electric machine to the target transmission input speed accelerated or a current electric machine speed above the target transmission input speed held. Subsequently the switching element is closed and the internal combustion engine, such as described above as soon as he reaches the desired target speed has reached, fired, so a fuel-air mixture for ignition brought.

at A start-up procedure is a direct start as a start mode especially advantageous because the electric machine and the internal combustion engine Have zero speed, making it more favorable in terms of starting time is the combustion engine simultaneously with the electric machine to accelerate with. Here, the (first) clutch, when in neutral switched gear or, if between the electric machine and the Gear a second clutch is arranged, when open second second clutch, initially closed and then the internal combustion engine by means of the electric machine with increasing speed accelerated. The internal combustion engine will turn, as soon as he desired target speed has reached, fired. in principle is at a starting process and a swing start and electrical Drive also a direct start possible.

to Setting or maintaining the target transmission input speed can the internal combustion engine with regard to its control and regulation even temporarily operated in a speed mode. However, it can also be provided that the internal combustion engine via an engine control unit temporarily a drive torque is specified and the electric machine in a speed mode, depending on requirement, motor or generator operated, to adjust the target transmission input speed.

Furthermore can be provided that the unfire startup of the engine or more gas exchange valves of a valve train of the internal combustion engine stay closed. As a result, as far as a valve train control this allows an internal resistance of the internal combustion engine be kept relatively low when increasing the speed. Especially is a gas spring effect, by filling and expelling the Cylinder fills with air and an acceleration the engine counteracts with increasing speed, largely avoided which further reduces the time required to reach the target speed leaves.

at a second process sequence according to the invention can be advantageously provided that the internal combustion engine by means the electric machine with the switching element closed to the target transmission input speed is started up, the engine firing at one speed independently below the target transmission input speed starts.

Therefore In this process, the injection timing can not be freely selected. Rather, the fuel injection when accelerating the Internal combustion engine independently, so motor-controlled independent from reaching the target transmission input speed, beyond a certain one Speed. However, the startup process is not left to the combustion engine, but made or supported by the coupled electric machine. Thus, in this embodiment, an electric motor-internal combustion engine combined raising the speed of the crankshaft of the internal combustion engine to the predicted target transmission input speed.

to Clarification of the invention, the description is a drawing an embodiment attached. In this shows

1 a schematic representation of a hybrid drive 1 a vehicle for carrying out an operating method according to the invention.

Accordingly, in 1 a schematic of a vehicle hybrid drive 1 with a parallel hybrid powertrain 2 represented as it may be provided for example for a commercial vehicle (truck, bus, van, special vehicle). The powertrain 2 has an internal combustion engine 3 , For example, a diesel engine, with a crankshaft 24 on that over a switching element 4 with an electric machine 5 is connectable. The electric machine 5 is via a transmission input 6 with a gear 7 coupled to the switching of translations. The in 1 illustrated powertrain 2 is thus designed as a 1K-ISG arrangement, ie with a separating or starting clutch as a switching element 4 for coupling the internal combustion engine 3 to the drive train 2 and the drive connection to the electric machine 5 , A second separate switching element between the electric machine 5 and the transmission 7 is not available separately. The transmission 7 can an unspecified power take-off (PTO: Power Take-Off) 8th be subordinate. About a downforce 25 and a differential 9 can each applied output torque of the hybrid drive 1 to a drive axle 10 and about this to the drive wheels 11 to get redirected.

The electric machine 5 can be operated depending on the operating situation as an electric drive unit or as a generator. She is with a converter 12 connected by an inverter control unit 13 is controllable. About the inverter 12 is the electric machine 5 with an electric drive energy storage 14 , For example, a 340 V high-voltage battery (supercaps are also possible) connected. In motor operation, the electric machine 5 from the energy store 14 fed. In generator mode, ie when driven by the internal combustion engine 3 and / or in Rekuperationsbetrieb, the energy storage 14 through the electric machine 5 electrically charged. Furthermore, the electric machine acts 5 as integrated starter generator (ISG) for starting the internal combustion engine 3 ,

The high-voltage circuit of the energy storage 14 or the control units connected thereto are via a bidirectional DC-DC converter (DC / DC) 15 to a vehicle electrical system (24 V or 12 V) 16 connected. The energy storage 14 is by means of a battery management system (BMS) 17 with regard to its state of charge (SOC) monitored and regulated. The DC-DC converter 15 is from a DC-DC converter controller 18 controllable. There is also a control unit 19 for unspecified brake control functions, in particular an anti-lock braking system (ABS) or an electronic brake system (EBS) and another control device 20 for an electronic diesel control (EDC) of the example designed as a diesel engine internal combustion engine 3 intended. The individual control units mentioned may also be combined, at least in part, in a control unit.

To control the drive train components is a control device 21 present in which a transmission control unit 21a (TCU: Transmission Control Unit) and a hybrid control unit 21b (HCU: Hybrid Control Unit) are integrated. For controlling the drive energy distribution or connection and disconnection of the two drive units 3 and 5 is a central strategy unit 22 intended. The strategy unit 22 communicates via a data bus 23 , For example, a CAN bus, with the controller 21 and the controllers 13 . 17 . 18 . 19 ,

Furthermore, according to the invention, designed as an electronic control unit, control means 26 present, on the one hand with the control device 21 and on the other hand with the electronic diesel control 20 are connected. By means of the control means 26 is in communication with the controller 21 the speed of the electric machine 5 and in conjunction with the diesel regulation 20 the speed of the internal combustion engine 3 and the beginning of the injection of fuel in the combustion chambers during a starting process by means of the electric machine 5 with closed switching element 4 at a traction interruption during a switching operation of the transmission 7 adjustable.

An inventive method for operating the hybrid drive 1 is based on a regulation of a starting speed of the internal combustion engine 3 during a starting process during a shift of the transmission 7 with a traction interruption.

At a start request for starting the internal combustion engine 3 and a coincident shift request for gear change of the transmission 7 during electric travel, ie when the clutch is open 4 and stationary internal combustion engine 3 , is first, according to a swing start, the electric machine 5 during the interruption of tractive effort when the transmission is in neutral 7 governed by the control means 26 to a predicted from the transmission ratio of a selected sequence and the vehicle speed target input speed of the transmission input 6 accelerates and then the clutch 4 closed.

Subsequently, the internal combustion engine 3 from the electric machine 5 turned up to the target transmission input speed, without the internal combustion engine is fired, so it is supplied with fuel. The firing is by means of the diesel control 20 only triggered when the internal combustion engine 3 has reached the target transmission input speed. Subsequently, the internal combustion engine transmits 3 , with the electric machine 5 circulating in the block, directly the required synchronous speed for inserting the following gear on the transmission input 6 so that the target gear is engaged and the circuit is completed, in which case the traction in the drive train can be restored. The internal combustion engine 3 Subsequently, according to a strategy specification, the vehicle either drives the electric motor assisted by the electric machine 5 or the electric machine 5 operating as a generator.

Alternatively, the internal combustion engine 3 in the case of a start request, for example during a start-up procedure, with the transmission switched to neutral and the vehicle stationary, corresponding to a direct start, from the outset with the electric machine 5 by closing the switching element 4 get connected. Subsequently, the crankshaft 24 of the internal combustion engine 3 by means of the electric machine 5 accelerated to a target transmission input speed of a target or Anfahrganges and upon reaching the target speed firing the engine 3 initiated.

In a further possible process sequence during an electric drive or when starting up, the fuel injection starts automatically at a certain speed and the internal combustion engine 3 is, by the electric machine 5 controlled, ramped up to the target speed, so that in turn the synchronous speed of the target or starting gear at the transmission input 6 is applied.

1

hybrid drive

2

powertrain

3

internal combustion engine

4

switching element

5

electric machine

6

transmission input

7

transmission

8th

PTO

9

differential

10

drive axle

11

vehicle

12

inverter

13

Inverter control unit

14

electrical Drive energy storage

15

DC converter

16

board network

17

Battery Management System

18

Voltage converter control device

19

electronic brake control

20

electronic diesel control

21

control device

21a

Transmission control unit

21b

Hybrid control unit

22

strategy unit

23

bus

24

crankshaft

25

output

26

control means

SECTION

Anti-lock braking system

BMS

Battery management system

DC / DC

DC converter (Direct Current / Direct Current)

EBS

electronic Braking system (Electronic Brake System)

EDC

electronic Diesel control (Electronic Diesel Control)

HCU

hybrid control (Hybrid control unit)

TCU

transmission control (Transmission Control Unit)

PTO

PTO (Power take-off)

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

• US 20050221947 A1 [0007]
• DE 102005051382 A1 [0007, 0010]
• DE 102005007966 A1 [0010]

Claims (10)

Method for operating a hybrid drive ( 1 ) of a vehicle, with a parallel hybrid powertrain ( 2 ) comprising an internal combustion engine ( 3 ), at least one electric machine ( 5 ), at least one in power flow direction between the internal combustion engine ( 3 ) and the electric machine ( 5 ) arranged switching element ( 4 ), a transmission ( 7 ) and an output ( 25 ), in which for starting the internal combustion engine ( 3 ) by means of the electric machine ( 5 ) the switching element ( 4 ) is closed, characterized in that during a starting operation of the internal combustion engine ( 3 ) during a traction interruption in a switching operation of the transmission ( 7 ) a starting speed of the internal combustion engine ( 3 ) is directly controlled to a predicted target transmission input speed of a follower transmission, wherein the beginning of a firing of the internal combustion engine ( 3 ) is optionally correlated with the speed control. A method according to claim 1, characterized in that a respective target transmission input speed from the intended follow ratio and from the current speed of the output ( 25 ), the driving speed or derived variables. Method according to Claim 1 or 2, characterized in that the internal combustion engine ( 3 ) by means of the electric machine ( 5 ) with closed switching element ( 4 ) is ramped up to the target transmission input speed, wherein the engine firing is initiated upon reaching or nearing the target transmission input speed. Method according to Claim 1 or 2, characterized in that the internal combustion engine ( 3 ) by means of the electric machine ( 5 ) with closed switching element ( 4 ) is ramped up to the target transmission input speed, wherein the engine firing automatically starts at a speed below the target transmission input speed. Method according to one of claims 1 to 4, characterized in that the internal combustion engine ( 3 ) is started by means of a swing start, in which initially with the switching element ( 4 ) on the electric machine ( 5 ) set the target transmission input speed or maintain a current speed above the target transmission input speed, and then hold the shift element ( 4 ) is closed. Method according to one of claims 1 to 4, characterized in that the internal combustion engine ( 3 ) is started by means of a direct start, in which the switching element ( 4 ) at stationary or at a speed below the target transmission input speed rotating electric machine ( 5 ) first closed and then the internal combustion engine ( 3 ) by means of the electric machine ( 5 ) is accelerated with increasing speed. Method according to one of claims 1 to 6, characterized in that the internal combustion engine ( 3 ) is operated temporarily to set the target transmission input speed in a speed mode. Method according to one of claims 1 to 6, characterized in that the internal combustion engine ( 3 ) is set to set the target transmission input speed temporarily a drive torque and the electric machine ( 5 ) is operated in a speed mode, depending on requirements, motor or generator. Method according to one of claims 1 to 8, characterized in that during startup of the internal combustion engine ( 3 ) without firing one or more gas exchange valves of a valve train of the internal combustion engine ( 3 ) stay closed. Device for operating a hybrid drive ( 1 ) of a vehicle, with a parallel hybrid powertrain ( 2 ) comprising an internal combustion engine ( 3 ), at least one electric machine ( 5 ), at least one in power flow direction between the internal combustion engine ( 3 ) and the electric machine ( 5 ) arranged switching element ( 4 ), by means of which the internal combustion engine ( 3 ) with the electric machine ( 5 ) is frictionally connectable, a transmission ( 7 ) and an output ( 25 ), characterized in that control means ( 26 ) are provided, by means of which, at a start of the internal combustion engine ( 3 ) by means of the electric machine ( 5 ) during a traction interruption in a switching operation of the transmission ( 7 ), a starting speed of the internal combustion engine ( 3 ) directly to a predicted target transmission input speed of a sequence ratio controllable and the beginning of a firing of the internal combustion engine ( 3 ) is optionally correlatable with the speed control.