DE102005037515A1 - Gear change, with a parallel gearbox, holds the clutch of the old gear setting in a non-slip condition while the other clutch torque is raised to the motor torque and the first clutch is opened - Google Patents

Abstract

To control the clutches (K1,K2) of a parallel gearbox (22,24), when changing gear, the clutch for the old gear setting is held in a non-slip condition while the torque for the clutch for the new gear setting is raised to the actual motor torque and the first clutch is opened. An electronic control unit (26) acts on actuators (14,16,18,20) for the clutches, with sensors to register the vehicle operating parameters.

Description

The The invention relates to a method and a device for controlling the clutch of a parallel gearbox during a gear change.

parallel shift or double clutch gear find because of the possible through them Driving comfort, possible Consumption savings and the possible Traction interruption-free gear changes in modern vehicles increasingly use.

Usually in a dual-clutch transmission, a gear change takes place in such a way that at the beginning of the gear change the one associated with the old gear, first fully closed clutch is adjusted in slipping operation, while this slipping operation the clutch associated with the new gear is increasingly closed until it works almost without slippage and then the "old" clutch is fully opened. When adjusting the old clutch in slip mode is usually an engine intervention, for example, a revving of To avoid motor. The gear change is relatively time consuming in this way and with drawbacks connected. Furthermore, an exact knowledge of the torque characteristics the couplings required.

Of the Invention is based on the object, a method for controlling the clutches of a parallel gearbox during a gear change indicate, in a simple way, a quick gear change if necessary without engine intervention possible. The invention is further based on the object, a device for Carry out of the procedure.

• – Halten der dem alten Gang zugeordneten Kupplung in nicht schlupfender Stellung,
• – Erhöhen des von der dem neuen Gang zugeordneten Kupplung übertragbaren Moments bis auf das augenblickliche Motormoment und
• – Öffnen der dem alten Gang zugeordneten Kupplung.

The former part of the invention task is solved with a method for controlling the clutches of a parallel transmission in a gear change, comprising the following steps:

• Holding the clutch associated with the old gear in non-slipping position,
• - Increasing the transferable from the new gear associated clutch torque up to the instantaneous engine torque and
• - Opening the old gear associated clutch.

wobei

T_Eng

= stationäres Motormoment

ω ._Eng

= Motordrehzahländerung

J_Eng

= Trägheitsmoment des Motors

i_ges,neu

= Gesamtübersetzung im neuen Gang und

wobei

i_ges

= Gesamtübersetzung im alten Gang.

Advantageously, the torque transmittable by the clutch associated with the new gear is increased until the acceleration ω. _{Wheels of} a vehicle wheel assumes the following value:

in which

T _Eng

= stationary engine torque

ω. _Closely

= Engine speed change

J _Eng

= Moment of inertia of the motor

i _{ges, new}

= Overall ratio in the new gear and

in which

i _ges

= Overall translation in the old gear.

wobei

i_ges,ges

= Gesamtübersetzung im neuen Gang und

i_ges

= Gesamtübersetzung im alten Gang.

In an alternative embodiment of the method according to the invention, the torque which can be transmitted by the clutch associated with the new gear is increased until the acceleration ω. _{Wheels of} a vehicle wheel assumes the following value:

in which

i _{ges, sat}

= Overall ratio in the new gear and

i _ges

= Overall translation in the old gear.

The the old gear associated clutch can be opened in such a way that they are at the end of the raise the moment of the clutch associated with the new gear is open.

The The old gear associated clutch can be opened suddenly.

wobei

TrqCl_Oldatbegin

= von der dem alten Gang zugeordneten Kupplung übertragbares Moment zu Beginn des Gangwechsels.

Alternatively, the clutch associated with the old gear may be opened according to the following relationship:

in which

TrqCl _Oldatbegin

= from the old gear associated clutch transmissible torque at the beginning of the gear change.

Farther may be provided to bias the gear actuator of the old gear, this means, the switching operation for the old gear with a predetermined force to apply so that with the clutch of the old gear closed only by the predetermined force is pulled out and thus transmits no more moment, if the friction clutch of the new gear sufficient moment on the Transmission input shaft transmits. there becomes the force neutral between the biasing force of the actuator and the frictional force for laying the old gear through the over the transferred to old gear Remaining moment determines that with takeover of the moment through the friction clutch of the new gear increasingly decreases. In this way, an overlap circuit can also without immediate opening the clutch of the old gear done.

A Device for controlling the clutches of a parallel shift transmission contains at a gear change an electronic control device for driving actuators of Couplings, which control device with sensors for detecting Operating parameters of a vehicle is connected and the actuators under execution one or more of the aforementioned methods controls.

The Invention will be described below with reference to schematic drawings, for example and explained in more detail.

In the figures represent:

1 a schematic diagram of a dual-clutch transmission with control device,

2 a block diagram of a simplified vehicle model,

3 and 4 Curves to explain the method according to the invention.

According to 1 For example, a double-clutch or parallel-shift transmission known per se has a drive shaft driven, for example, by an internal combustion engine 6 on, with two input shafts 8th and 10 rotatably connected. The torque flow from the drive shaft 6 in the input shafts 8th and 10 is via either a clutch K1 and K2 selectively controllable. Between the input shaft 8th and an output shaft 12 are wheel pairs, of which only one is shown, different translations switchable. Likewise, between the input shaft 10 and the output shaft 12 different wheel pairs switchable, of which only one is shown. To actuate the clutches K1 and K2 are actuators 14 and 16 intended. For switching the wheel pairings, for example, to establish a rotationally fixed connection zwi on the input shaft 8th or 10 arranged wheel with the respective input shaft 8th or 10 that meshes with a respective, permanently connected to the output shaft rotatably connected wheel are actuators 18 and 20 intended.

The on the input shaft 8th arranged wheels are for example wheels, with each of which a straight gear and a reverse gear is switched. With the input shaft 10 wheels are connected, with each of which an odd gear is switched. Thus, the dual-clutch transmission consists of two in total 22 and 24 designated sub-transmissions, the drive shaft 6 with the output shaft 12 and one of which contains, for example, the even gears and the reverse gear and the other the odd gears.

For controlling the actuators 14 . 16 . 18 and 20 serves an electronic control device 26 with microprocessor and associated program and data memories whose outputs each control one of the actuators and their inputs 28 connected to non-illustrated sensors of the vehicle or vehicle drive train, such as a sensor for detecting the position of an accelerator pedal, a sensor for detecting the engine speed and the rotational speed of the drive shaft 6 a sensor for detecting the rotational speed of the output shaft 12 or sensors for detecting the rotational speed of the driven vehicle wheels, a sensor for detecting the position of a gear selector lever, with the different Fahrpro programs activated or directly the desire to insert a particular gear can be signaled, etc.

The illustrated control device 26 can be connected via a bus system with other control devices of the vehicle, such as an engine control unit with which a power actuator of the engine is controlled.

The structure of the actuators 14 . 16 . 18 and 20 can be of various kinds, for example, the actuators may be hydraulic actuating cylinder, the pressure of which is one of the control device 26 controlled hydraulic system is controlled. The actuators may include electric motors that drive an actuator. In this case, the position of the actuator is advantageously detected by a respective further sensor, so that the functional state of the respective actuated by the actuator unit in the control device 26 is known.

As is known per se, the torque transferable by the clutch is important for the function of a clutch, that in a memory of the control device 26 is stored as a curve indicating the transmittable clutch torque depending on the position of a clutch actuator, such as a clutch actuating lever. Since the functional state of the clutch changes due to wear and the like, the characteristic curve has to be updated from time to time, which occurs when certain points of the clutch, for example a gripping point or a fully opened or fully closed state of the clutch, are approached in a homing procedure is and the respective associated position of the actuator or actuator is detected and updated.

The previously described units, referencing, etc. are on are known and are therefore not explained in detail.

In a dual-clutch transmission according to 1 In each case a gear can be engaged in the partial transmission whose clutch is open, while the effective gear ratio of the transmission is determined by the partial transmission whose clutch is closed. Suppose, in the partial transmission 24 be the fourth gear engaged and the clutch K2 is closed, then is for the translation between the drive shaft and output shaft 12 the fourth gear is effective. Let's assume, in the partial transmission 22 will be inserted as a new gear to be switched third gear. When switching the transmission from fourth to third gear then the clutch K2 must be opened. If the clutch K1 takes over the torque transmission, if none of the clutches slips, the transmission would be destroyed by the overdetermination of the translations. Previously, it was customary to perform such a gear change such that in the example shown, the clutch K2 is opened at the beginning of the shift to slipping operation, the clutch K1 is closed and the clutch K2 is then fully opened, to avoid an increase in engine speed advantageously an engine intervention takes place, within which the torque delivered by the engine is briefly reduced. This switching method requires relatively long switching times, is complex due to the engine engagement coupled thereto, possibly means an acceleration loss and is sensitive to inaccuracies in the torque characteristic of the clutches.

Accordingly, the invention described below aims at a faster and easier by To provide a feasible method for a gear change of a dual-clutch transmission.

2 shows a simplified model of a vehicle. T _ENG denotes the engine torque. J _ENG denotes the moment of inertia of the motor; T _CL is the clutch torque. i _ges is the total ratio between the speed of the wheels and the speed of the crankshaft of the engine. J _Veh is the vehicle _{moment of inertia} . T _Veh is the vehicle torque and T _{Veh , Res} is the driving resistance.

From the 2 the following equations can be taken immediately:

wobei n der Wirkungsgrad des Getriebes bzw. der Übersetzungen vom Fahrzeugrad bis zur Antriebswelle 6 ist.The relationship between the clutch torque T _C1 and the vehicle torque T _Veh is described by the following equation:

where n is the efficiency of the transmission or the translations from the vehicle to the drive shaft 6 is.

Equation (3a) can be rewritten by introducing a factor "factor *" as follows. T Cl ∙ i ges = T Veh Factor * (3)

When equations (1) and (2) are substituted into equation (3), we obtain:

Since the inertia of the vehicle J _{Veh is} also an unknown, it is additionally included in a factor "Factor", so that the result is:

With the aid of equation (5), the clutch torque can be calculated by substituting the right side of equation (2) into equation (5):

If in parallel gearbox according to 1 a gear change with a torque overlap without slip of the "old" clutch (the clutch, which is closed before the gear change, ie the old gear is assigned), the "old" clutch initially remains closed and the "new" clutch is as long as in the direction Closed position can be adjusted or raised until the "new" clutch has taken over the engine torque and the "old" clutch no longer transmits a moment. After that, the "old" clutch will be opened suddenly, for example.

The problem occurring in the aforementioned process is to detect the situation in which the "new" clutch has taken over the engine torque in a timely and reliable manner. One way to do this is explained below:
Until the overlap, the variable "Factor" is continuously determined according to the formula (5). Assuming that the running resistance, the transmission efficiency and the inertia of the vehicle do not change during the phase of overlap of the torques transmitted by both clutches (factor = constant), the vehicle acceleration after the overlap can be determined. For this the formula (6) is rewritten in:

i _{ges, new} means the overall translation when the new gear is effective. Since a situation is to be detected in which the "new" clutch has taken over the engine torque, the clutch torque in the numerator of equation (7) can be replaced by equation (2). This results in:

The means that the "old" coupling to drive train tension and thus loss of comfort too avoid being opened must be as soon as the vehicle acceleration is equal to that from the Formula (8) is calculated value. The value for the variable "Factor" becomes the value used by the variable at the beginning of the switching operation, i. just before the overlapping Actuation of the couplings has.

The aforementioned method can be simplified if it is additionally assumed that the engine torque does not change or only slightly changes during the overlapping operation of the two clutches. By substituting the equation (5) into the equation (8) and shortening the engine torque and the dynamic ratio, the following equation is obtained.

In 3 curves are shown that represent a sequence of the method according to the invention of a gear change with torque overlap without slippage. In the top diagram is the course of the wheel acceleration with ω. designated. The curve according to formula (8) or formula (9) is denoted by ω. _thres .

The diagram below shows the course of the vehicle _acceleration a _Veh .

The step curve underneath shows the change in the overall ratio i _ges caused by the gear change.

In the penultimate diagram is the torque transmitted by the "old" clutch with TrqCl1 and that transmitted by the "new" clutch Moment called TrqCl2.

In the bottom diagram, the course of the engine speed is denoted by N _Eng .

The passing through all the diagrams whose abscissa indicates the time vertical dashed line indicates the time of equality between the measured wheel acceleration and that according to the formulas (8) or (9) calculated wheel acceleration.

As As can be seen, the transferable from the "old" coupling Moment during the overlap held at the initial level and, in short, before the equality of acceleration (top diagram) is reached, the "old" clutch opened quickly. With equal acceleration is the "old" clutch Completely open, so that no vibrations are caused.

wobei bedeuten:The "old" coupling does not necessarily have to be opened abruptly or abruptly, but can be opened continuously. This is possible because the overlapping actuation occurs from a torque tracking, where the "old" clutch can transmit a greater engine torque than the actual engine torque, including its dynamic portion, to ensure that the clutch does not slip. This offset is maintained at the beginning of an overlapping operation of the clutches, ie at the beginning of a gear change, and then reduced according to the following formula:

where:

TrqCl _Old

= transferable from the "old" coupling Moment,

ω. _{Wheels, thres}

= according to the formula (8) or (9) calculated speed change a vehicle wheel,

ω. _{Wheelsatbegin}

= Speed change a vehicle wheel at the beginning of the circuit,

ω. _{Wheels thresatbegin,}

= according to the formula (8) or (9) calculated speed change a vehicle wheel at the beginning of a circuit with old translation and

TrqCl _Oldatbegin

= transferable from the "old" coupling Moment at the beginning of the circuit.

A circuit in which the "old" clutch "soft" according to the formula (10) is opened is in 4 represented, whose diagrams those of the 3 However, the vertical, dashed line indicates the time of the start of the circuit. As can be seen, the torque transmittable from the "old" clutch is continuously reduced from the beginning of the shift (stage in i _tot ) and, if equal, is between ω. and ω. _thres or when the increase of the transmissible by the "new" clutch torque (TrqCl2) stops briefly, and then again to be increased, dropped to zero.

If a sensor for detecting the speed of the transmission output shaft 12 ( 1 ) is present, the wheel or vehicle accelerations are advantageously not determined at the wheels, but directly at the transmission output.

The allow the above-described method or switching strategies a very fast switching with possible low acceleration drops and are opposite Torque errors of the clutches only slightly sensitive, since the clutches dependent controlled by accelerations.

6

drive shaft

8th

input shaft

10

input shaft

12

output shaft

14

actuator

16

actuator

18

actuator

20

actuator

22

subtransmissions

24

subtransmissions

26

control device

28

inputs

Claims (8)

Method for controlling the clutches of a parallel shift transmission during a gear change, comprising the following steps: - Hold the old gear associated clutch in non-slipping position, - Increase the from the clutch associated with the new gear transferable moment up the instantaneous engine torque and - Opening the old gear assigned Clutch. The method of claim 1, wherein the torque transmissible by the clutch associated with the new gear is increased until the acceleration ω. _{Wheels of} a vehicle wheel assumes the following value:

where T _Eng = stationary engine torque ω. _Eng = engine speed change J _Eng = moment of inertia of the engine i _{ges, new} = total ratio in the new gear and

where i _ges = total translation in the old gear. The method of claim 1, wherein the torque transmissible by the clutch associated with the new gear is increased until the acceleration ω. _{Wheel of} a vehicle _wheel assumes the following value:

where i _{ges, neu} = total gear ratio in the new gear and i _ges = overall gear ratio in the old gear. Method according to one of claims 1 to 3, wherein the the old gear associated clutch after the end of the increase of the Moments of the new gear associated clutch is open. Method according to one of claims 1 to 4, wherein the the old gear assigned clutch is opened suddenly. A method according to claim 2 or 3, wherein the clutch associated with the old gear is opened according to the following relationship:

where TrqCl _Oldatbegin = torque _{transmittable} from the clutch associated with the old gear at the beginning of the gear shift. Device for controlling the clutches (K1, K2) of a parallel shift transmission ( 22 . 24 ) during a gear change, comprising an electronic control device ( 26 ) for controlling actuators ( 14 . 16 ) of the clutches, which control device is connected to sensors for detecting operating parameters of a vehicle and the actuators ( 14 . 16 ) is controlled by performing a method according to one or more of claims 1 to 6. Method for controlling the clutches of a parallel shift transmission during a gear change, comprising the following steps: - Hold the one engaged, old gear associated clutch in not slipping position, - Increase the from the clutch associated with a new gear transferable moment up the instantaneous engine torque and - Acting on an actor for laying out the old gear with a predefinable preload force, wherein the actuator is in the presence of an equilibrium relationship between Preload and friction, transmitted from the old gear Moment more dependent Holding force interprets the old gear.