WO2015014614A2

WO2015014614A2 - Method and device for coupling an internal combustion engine during deceleration

Info

Publication number: WO2015014614A2
Application number: PCT/EP2014/065215
Authority: WO
Inventors: Markus Vogelgesang; Manuel Schnitzer; Stefan Hoefle
Original assignee: Robert Bosch Gmbh
Priority date: 2013-08-01
Filing date: 2014-07-16
Publication date: 2015-02-05
Also published as: CN105408652A; DE102013215101A1; CN105408652B; KR20160039281A; WO2015014614A3

Abstract

The invention relates to a method for coupling a drive motor (2) into a drive train, comprising the following steps: - determining a rotational speed difference (n_diff) between an input side and an output side of a clutch (4); and - controlling the clutch (4) by predefining a desired clutch torque (M_{Kupplung_soll}) to be transmitted as a function of the rotational speed difference (n_diff).

Description

description

title

Method and device for coupling an internal combustion engine during a deceleration process

Technical area

The invention relates generally to the field of propulsion systems, and more particularly to methods of operating clutch trains in powertrains of

Motor vehicles.

State of the art

In the context of the increasing automation of many functions in motor vehicles, the function of Ankuppeins an internal combustion engine to a drive train using a clutch can be performed automatically controlled. This is the case in particular in automatic or semi-automated transmissions in motor vehicles.

If a vehicle is in sailing mode, ie the vehicle is rolling when the internal combustion engine is disconnected, then with a suitable trigger, a function must be used, eg. B. by a driver assistance function, the internal combustion engine to be connected to the drive train again. When sailing the vehicle, the clutch is open and the engine speed of the engine is independent of and generally deviates from the transmission input speed. After coupling the internal combustion engine, the clutch is closed and the engine speed corresponds to the transmission input speed. The triggering of Einkuppeins the internal combustion engine, for example, after pressing the brake pedal by the driver or due to a request for braking by a driver assistance system or the like, as a closing of the drive train and a subsequent co-rotating or entrainment of the internal combustion engine in overrun, for example, to support the braking process may be desired. Also, the internal combustion engine may be coupled according to a requirement and additional energy may be provided for charging a battery.

Furthermore, engagement of the internal combustion engine may be required in that an additional drive torque is required for establishing a negative pressure for a brake booster or the like.

The coupling of the internal combustion engine to the drive train is perceived by the driver as a jerking in a non-optimal control, which is usually an impairment of ride comfort.

For example, a control method for automobiles with an automated clutch device may be provided. An engagement from a sailing operation of the motor vehicle takes place by detecting the speed of the output shaft of the transmission and closing the engine speed in such a way that the two speeds coincide or are aligned with one another before the clutch is released to leave the sailing mode.

A method for operating a motor vehicle is known from DE 10 2010 003 673 A1, in which a gear recommendation is provided during a freewheeling operation and a current rotational speed of the drive motor is accelerated to a recommended rotational speed, which corresponds to the gear recommendation in a current speed situation of the motor vehicle.

It is also possible to provide for the engagement of an internal combustion engine with a power take-off train from a sailing condition, to increase the rotational speed of the output shaft of the internal combustion engine in accordance with a drive energy course given by the driver. Disclosure of the invention

According to the invention, a method for coupling a drive motor, in particular an internal combustion engine, to a drive train according to claim 1 and the device, the drive system and the computer program according to the independent claims are provided.

Further advantageous embodiments of the present invention are specified in the dependent claims.

According to a first aspect, there is provided a method of engaging a drive motor to a drive train, comprising the steps of:

- determining a speed difference between an input side and an output side of a clutch; and

- Driving the clutch by specifying a target clutch torque to be transmitted depending on the speed difference.

When engaging an internal combustion engine (drive motor) this is towed by the clutch or accelerated from an idle speed, so that the engine speed equalizes the transmission input speed. The applied clutch torque is noticeable to the driver as a deceleration of the motor vehicle. Therefore, for reasons of comfort on the one hand, the clutch torque must not be too high and on the other there should be no momentary jumps, as these are perceived as a jerky change in the longitudinal acceleration. Momentum jumps are caused by abrupt setpoint changes as well as by a non-steady transition from clutch torque to

Verbrennerschleppmoment.

According to the above method is provided, the towing the internal combustion engine according to a controlled

To make speed gradient curve, thereby allowing a comfortable and smooth closing of the drive train from a sailing operation, ie in uncoupled combustion engine. In particular, the comfortable and smooth towing of the internal combustion engine from a standstill is thereby made possible, as occurs, for example, usually in a start / stop sailing operation. Even if the internal combustion engine Peltem powertrain is idle, the above method allows improved engagement, in which jerking or significant changes in the longitudinal acceleration of the motor vehicle can be avoided.

The above method provides to specify the transmission torque based on a specification of a speed gradient and based on a controller intervention. By specifying the speed gradient instead of the speed, a high level of comfort is achieved while driving, since no jerking or sudden change in the speed gradient can occur.

Furthermore, the driving of the clutch can be performed depending on the speed difference above a predetermined lower speed threshold.

It can be provided that, below the predetermined lower speed threshold value, the activation of the clutch is carried out in accordance with a predetermined constant desired clutch torque.

According to one embodiment, the driving of the clutch can be performed depending on the speed difference below a predetermined upper speed threshold, which depends in particular on a speed on the output side of the clutch.

Furthermore, above the predetermined upper speed threshold value, the activation of the clutch can be carried out in accordance with a continuously increasing nominal clutch torque.

It may be provided that the driving of the clutch is performed depending on the speed difference according to a predetermined, dependent on the speed difference gradient of the engine speed, wherein the gradient of the engine speed requires an inertia of the drive motor caused additional torque required by the target clutch torque becomes. It may be provided a control to compensate for deviations of an actual engine speed gradient of a target engine speed gradient, which is predetermined by the gradient of the engine speed.

According to a further aspect, an apparatus, in particular a control unit, is provided for engaging a drive motor to a drive train, the apparatus being designed to:

to determine a speed difference between an input side and an output side of a clutch; and

- Actuate the clutch depending on the speed difference so that a desired clutch torque is transmitted.

In another aspect, a drive system is provided, comprising:

a drive motor;

a drive train;

a clutch for coupling the drive motor to the drive train to transmit a clutch torque; and

- The above device.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

Figure 1 is a schematic representation of a drive system with a

Drive train with a clutch for automatic engagement of an internal combustion engine; FIG. 2 shows a flowchart for illustrating a method for

Engaging an internal combustion engine to a drive train;

Figure 3 is a schematic functional representation for determining a desired transmission torque of the clutch; and a speed torque diagram illustrating the Verläu fe of clutch torque, speed, requested braking torque and engine torque.

Description of embodiments

FIG. 1 shows a schematic representation of a drive system 1 for a motor vehicle. The drive system 1 comprises an internal combustion engine 2 as a drive motor, which via a drive shaft 3 with a clutch 4 and a

Transmission 5, which together form a drive train is connected.

On the output side of the transmission 5, this is connected via a drive axle 6 with drive wheels 7. The drive system 1 can be operated in different operating modes depending on the operating state of the motor vehicle. In normal operation, the clutch 4 is closed, so that the internal combustion engine 2 via the gear 5 and the drive shaft 6, the drive wheels 7 drives. In an idle sailing operation, the engine 2 is idling and the clutch 4 is open. In this case, the vehicle rolls on its own kinetic energy in the

Idle sailing mode. In a start / stop sailing operation, the engine 2 is turned off and opened at a standstill and the clutch 4, so that the vehicle also rolls due to its kinetic energy. If a brake intervention by pressing a brake pedal 8 requested by a driver or a braking intervention is automatically requested by a driver assistance system, so in a start / stop sailing operation in which the engine 2 is turned off, a part of the braking torque by towing the engine. 2 or be provided by a coasting operation of the internal combustion engine 2. This allows brake pads of the

Vehicle brakes (not shown) are spared. Also, it may be necessary for other reasons to leave the sailing operation and close the clutch 4. When closing the clutch 4, it is necessary during a transition the

Tnebe speed of the engine 2 to the transmission input speed n _Ge on the input side of the transmission 5 to match. Thus, the adjustment of the speed as smooth as possible, ie with a high level of comfort for the driver, it is necessary to specify the clutch torque of the clutch 4, that is, the torque that is transmitted through the clutch 4. For this purpose, a control unit 9 is provided, which the clutch 4 according to a predetermined target

Clutch torque M _K uiung_soii using an actuator (not shown) in the clutch 4 controls.

A method for determining the desired clutch torque M _K up iung_soii will be described in detail below with reference to the flowchart of Figure 2. The functional diagram of Figure 3 illustrates the determination of the desired clutch torque MKu iung _. Soii, to provide the smoothest possible transition from a sailing operation to a normal operation of the drive system 1 available.

In a first query step S1 is checked whether the clutch 4 is to be engaged during a sailing operation to z. B. to achieve a braking torque by a coasting operation of the engine 2. If a request for a drive train engagement is detected in step S1 (alternative: yes), the method is continued with step S2; otherwise (alternative: no) returns to step S1.

In the query step S2 is queried whether the internal combustion engine 2 is idling or at a standstill. If the internal combustion engine 2 is idling (alternative: 1), the method is continued with step S5; otherwise, d. H. if the engine is at a standstill (alternative: 2), the procedure continues with step S3.

In step S3 it is provided that the internal combustion engine 2 is turned on by a partial closing of the clutch 4. For this purpose, a constant setpoint

Clutch torque M _Ku ppiung_soii deferred until one of the cylinders reaches the top dead center and a lower speed threshold, z. B. a speed between 100 and 200 U / min, in particular 150 U / min, is reached. This is queried in step S4. If it is determined in step S4 that the upper

Dead center in one of the cylinders and the predetermined lower speed threshold lenwert is reached (alternative: Yes), the method is continued with step S5; otherwise (alternative: no) returns to step S3. Alternatively, only reaching or exceeding the speed threshold value can be queried.

Exceeding the first top dead center of a cylinder of the internal combustion engine 2 is critical, since a high clutch torque is required due to the high compression torque and the low kinetic energy of the internal combustion engine 2. This process can be assisted in motor vehicles with direct injection of fuel into the combustion chamber or by fuel pre-storage during engine run-off. This has the effect that in the first phase, a lower target clutch torque M _K uiung_soii can be specified, since the time-based combustion supports the exceeding of the first top dead center in the respective cylinder. Alternatively, this phase by an additional starter unit (not shown), such. As a starter, supported or without specification of the desired clutch torque MKu iung _. Soii, ie at a target clutch torque M _K up iung_soii of zero, are performed.

If the drive system 1 is in an idle-sailing mode, then the internal combustion engine 2 is idling, so that the predetermined speed threshold has already been exceeded. In this case, the process proceeds to step S5 as provided in step S2.

In step S5, in a second phase, the target clutch torque M _K up iung_soii is set according to the functional diagram of FIG. The base of the adjusted target clutch torque M _K up iung_soii forms a calculated or predetermined drag torque M _sch iepp of the engine 2. The drag torque Mschiepp can be calculated by a moment structure which is provided in the motor control. This z. B. the engine friction and coupled ancillaries are taken into account.

Using a correction map 1 1, the drag torque M _sch is iepp corrected and a corrected drag torque M _sch iepp provided '. Furthermore, an additional torque M _{z is} provided which corresponds to the moment of inertia of the internal combustion engine 2 when it is accelerated with a predetermined rotational speed gradient dn / dt. The additional torque M _z is added to the corrected drag torque M _sch ie 'in an addition element 12. The additional torque M _z is obtained by multiplying a predetermined moment of inertia J _M motor of the internal combustion engine 2 with a desired speed gradient dn _so n / dt in a multiplier 14. The target speed gradient dn _so n / dt results from a predetermined acceleration map 13, the Depending on the speed difference n _d iff between an engine speed of the internal combustion engine 2 and a transmission input speed n _Ge transmission of the transmission 5 the setpoint

Speed gradient dn _so n / dt pretends. It can be provided that the predetermined target speed gradient dn decreases _as n / dt when the speed difference ridiff decreases. It is further provided a control unit 15 which is adapted to the

Set speed gradient dn _so n / dt. For this purpose, an actual rotational speed gradient dn _ist / dt is provided and a difference dn dt between the target rotational speed gradient dn _so n / dt and the actual rotational speed gradient dn _ist / dt from a differential element 16 is provided to a control element 17. The control element 17 may comprise a proportional proportional controller and an integral component controller. The

Output variable of the control element 17 is fed to a second addition element 18, in which the output variable S of the control element 17 is added to the sum of the additional torque M _z and the corrected drag torque M _sch ie '. As a result, the target clutch torque M _Ku ppiung_soii is obtained, in accordance with which the actuator in the clutch 4 is actuated in order to set the corresponding transmission torque in the clutch 4 there. The control unit 15 is provided to compensate for inaccuracies of the modeling. The control member 17 provides a contribution of torque as a function of the deviation of the target and actual speed gradients.

In a next step S6 it is checked whether a speed difference between the engine speed and the transmission input speed n _Ge transmission has fallen below a certain predetermined speed difference threshold (or has exceeded a predetermined upper speed threshold). If this is the case (alternative: yes), the method is continued with step S7; otherwise (alternative: no) returns to step S5. Furthermore, it is checked in step S7, whether the falling below the predetermined speed threshold value has occurred during a predetermined period. If this is the case (alternative: yes), then in step S8 by continuous predetermined increase of the desired clutch torque M _K u iung_soii or by specifying a gradient of the desired clutch torque M _Ku ppiung_soii, z. B. a constant gradient, the remaining speed difference eliminated in a third phase. Otherwise (alternative: no), the program jumps back to step S5.

In Figure 4, the curves of the target clutch torque M _Ku ppiung_soii, the engine torque M _M otor, the engine speed are tor n _Mo, the transmission input speed gear n _Ge, the driver requested braking torque M _Br ems during a

One clutch or a closing of the clutch 4 and the thrust torque MMotor of the internal combustion engine 2 plotted against the time t. Starting from a sailing operation (phase SB) of the motor vehicle, in which the internal combustion engine 2 is at a standstill, the driver requests by pressing the brake pedal 8 a braking torque M _Br ems, which is shown by the dashed line.

In the first phase P1, the requested desired clutch torque M _Ku is ppiung_soii rapidly increased to a constant value M _Ku ppiungsoii * of the target clutch torque M _Ku ppiung_soii until a piston has reached the top dead center in a cylinder of the internal combustion engine 2 n is an engine speed _Mo has achieved tor, which is equal to or greater than a predetermined engine speed threshold. If this is achieved, the rotational speed gradient dn / dt is controlled in accordance with a predetermined course or regulated by the control unit 15 in the phase P2 in accordance with the method described in the functional diagram of FIG. It can be seen that during the second phase P2, the course of engine speed n _Mo tor approximates to the transmission input speed n _Ge tnebe and approaches asymptotically towards the end of second phase P2 thereto. If the speed difference has fallen below a predetermined speed difference threshold value, the setpoint clutch torque M _Ku ppiung_soii is increased in the third phase P3 according to a predetermined gradient until the clutch 4 is completely closed.

Claims

claims

1 . Method for engaging a drive motor (2) to a drive train,

comprising the following steps:

- Determining a speed difference (n _d iff) between an input side and an output side of a clutch (4); and

- Driving the clutch (4) by specifying a target clutch torque to be transmitted (M _K up iung_soii) depending on the speed difference (n _diff ).

2. The method of claim 1, wherein the driving of the clutch (4) dependent

from the speed _difference (n _dif f) above a given lower one

Speed threshold is performed.

3. The method of claim 2, wherein below the predetermined lower

Speed threshold, the driving of the clutch (4) according to a predetermined constant desired clutch torque (M _Ku ppiung_soii *) is performed.

4. The method according to any one of claims 1 to 3, wherein the driving of the clutch (4) depending on the speed _difference (n _dif f) below a predetermined upper speed threshold, which depends in particular on a speed on the output side of the clutch (4) performed becomes.

5. The method of claim 4, wherein above the predetermined upper speed threshold, the driving of the clutch (4) in accordance with a continuously increasing target clutch torque (M _K up iung_soii) is performed.

6. The method according to any one of claims 1 to 5, wherein the driving of the clutch (4) depending on the speed _difference (n _dif f) according to a predetermined, of the speed _difference (n _dif f) dependent gradient curve of the engine speed is performed, wherein the gradient curve the engine speed is increased by an inertia of the drive motor (2). set torque required by the desired clutch torque (M _K up iung_soii) is requested.

7. The method of claim 6, wherein a control is provided to compensate for deviations of an actual engine speed gradient (dn _ist / dt) from a target engine speed gradient (dn _so n / dt), which is predetermined by the gradient of the engine speed.

8. Device (9), in particular control unit, for engaging a drive motor (2) to a drive train, wherein the device (9) is designed to:

- To determine a speed difference (n _d iff) between an input side and an output side of a clutch (4); and

- Actuate the clutch (4) depending on the speed difference so that a desired clutch torque (M _Ku ppiung_soii) is transmitted.

9. drive system (1) comprising:

- a drive motor (2);

a drive train;

- A coupling (4) for coupling the drive motor (2) to the drive train to transmit a clutch torque; and

- A device (9) according to claim 8.

A computer program adapted to carry out all the steps of the method according to any one of claims 1 to 7.

1 1. Electronic storage medium on which a computer program is based

Claim 10 is stored.

12. Electronic control unit, which has an electronic storage medium according to claim 1 1.