DE102004027575B3 - Method for controlling an automatic clutch - Google Patents

Abstract

The invention relates to a method for controlling an automatic clutch, in which the input variables engine speed (n) and slip (S) between the engine and transmission are used to form a reference variable (Y) for the position of the clutch, wherein the engine speed (N Motor¶) a pilot control value (V) for the coupling position is formed and this is subsequently applied to a correction value (K), which is dependent on at least the sizes slip (S) between the engine output and transmission and the load request (LW).

Description

The The invention relates to a method for controlling an automatic Coupling according to the preamble of claim 1. Aim of the invention is the control of an automated clutch, especially for the controller the starting process, wherein all slip states of the driving operation z. For example, creep and low-speed behavior are included are.

automated Clutches find particular in automatic transmissions for vehicles Application. Previously known for Automatic transmission hydrodynamic converter between engine and transmission. These Transducer transferred while the torque generated by the engine by means of a hydrodynamic coupling on the gearbox. Hydrodynamic converters are due to their Construction with an over a fluid-coupled connection between input and output speed and slip dependent. A another possibility The clutch of automatic transmissions form friction clutches of operated electric or hydraulic actuators. Here is done accordingly a leader that the Einkuppelzustand the clutch describes a control of the clutch. This is mechanically operated, wherein the position of the clutch discs adjusted to each other according to requirements becomes. A control unit controls to an electric or hydraulically driven actuator to be the leader in one mechanical position of the clutch discs to each other. The needs-based education of this reference and their Implementation in a coupling position is thus the crucial Influencing factor for the driver experienced engagement and disengagement behavior of the automatic transmission. This largely determines the Acceptance of this type of power transmission. Especially noticeable are the dome operations in the starting and low-speed behavior of the vehicle.

Methods for controlling friction clutches are already known, wherein the simplest mechanical reaction takes place via a centrifugal governor. The actuation of the clutch takes place speed-controlled due to the principle of operation of the centrifugal governor. Another procedure is from the DE 36 06 229 A1 known. The control of an automatic friction clutch is controlled as a function of the slip and the driver's request. An engine speed is controlled according to an accelerator pedal position. Depending on the acceleration value of the accelerator pedal, a setpoint slip value is simultaneously determined via a characteristic map. The desired slip value is the reference variable for the coupling position. By comparing the rotational speeds, a measurement of the real slip value takes place, with an actuator setting the clutch according to the setpoint slip.

Of the Starting process depends It depends decisively on the application of the desired slip characteristic map. The engagement process takes place according to the acceleration of the accelerator pedal, in particular slow driving or creep behavior are only with limited Comfort feasible.

Furthermore, it is already known from the DE 44 09 122 C2 a method for controlling a clutch, in which a first setpoint value for the clutch position is determined from an input speed and a characteristic value for the load position, which results in a pre-control value for the desired value modified with the contact pressure. On the basis of the load request and the slip value as well as the input rotational speed, a correction value is determined which modifies the pilot control value. The resulting signal is specified as the clutch setpoint to the actuator of the clutch. An evaluation of the Lastistsignals does not take place. A direct adjustment of the Einkuppelcharakteristik to changing load conditions (train / thrust) is not possible.

Of the Invention is based on the object, a method of control to create an automated clutch, especially for the controller the startup process is suitable, wherein all slip conditions of the Driving z. For example, the creep and the low-speed behavior are included and be controlled with high ride comfort.

Low-speed behavior refers to the range of low vehicle speed regardless of actual startup and thus the load decoupling preferably from 0-ca. 30 km / h and decide on the arrival or decoupling of the vehicle from the drive in this Area.

These Task is in generic method for controlling automated clutches according to the invention the characterizing features of claim 1 solved. advantageous Embodiments of the invention result from the combination with the dependent claims.

The inventive method for controlling an automated clutch uses the input variables engine speed and slip between the engine and transmission to form a reference variable for the position of the clutch. It is formed from the engine speed before a tax value for the coupling position and this subsequently applied with a correction value, which depends at least on the sizes of slip between the engine output and transmission and the load request. Of the Load request can be formed by the evaluation of the load position transmitter. Furthermore, the signal of the actual value of the load is required in order to recognize the desired load shifts and load shifts as well as load changes (train / thrust) from the actual load value and load request. The method is particularly suitable for a comfortable control of the clutch during slow driving, so-called creep or low-speed behavior in low gears.

In In a further embodiment of the method, the correction value by a signal indicating the position and / or position change and / or Speed of change of position of the Load transmitter evaluates.

Of the Slippage between the engine output and transmission can in the method according to the invention measured as well as mathematically, for example by a model, be determined.

In a particularly advantageous embodiment of the invention is the Correction value, which is the speed-dependent formed precontrol value influenced, formed in two stages. To form the correction value will have a performance index of slip and load request as well Load actual value is dependent, educated. Furthermore, the formation of a converter cant, which is formed as a function of the slip and the load request. Converter overshoot and Key performance indicators have different functions. The structure of the invention allows a good coordination of the tax procedure, since KPI and Transformer overshoot separated can be adjusted. In the performance index is preferably the influence of the load change behavior shown, wherein the converter overshoot the Coordination of the different influences in full or partial load is being used.

A Further advantageous embodiment forms the normalization of the slip value. This is formed as the difference between engine and transmission speed and subsequently related to the maximum of the respective speed. By dividing the speed difference by the respective maximum value Slip does not reach values greater than 1. The slippage processing is thus considerably simplified in the tax procedure.

Further Details of the invention are described in the drawing with reference to FIG illustrated embodiments described. The embodiments are merely exemplary embodiments of the invention, which do not limit the scope of the invention.

in this connection demonstrate:

1 : A system representation of the method according to the invention as a block diagram and

2 : a block diagram of the slip calculation.

1 shows as input variables of the process of the invention the slip formed from the speeds of the engine _{the engine} and the gearbox N N S _transmission between the motor output and the transmission input, as well as the load request LW. In a first branch of the block diagram, a pre-control value V for the desired value of the coupling position Y is formed from the engine speed N _motor . This setpoint can be processed as a clutch setpoint torque, since a torque interface is usually implemented for automatic clutches. Any other interfaces can also be controlled by adjusting the setpoint. The pre-control value V results as a function of the coupling hardness 3 depending on the engine speed N _engine . The pre-control value V is subsequently corrected with a correction value K, from which the reference variable Y for the position of the clutch, usually the desired clutch torque, results. In a second branch of the block diagram, the correction value K is formed. This is formed on the basis of the slip S, the load request LW and the load actual value List. The correction value K is determined from two partial correction values, the performance index LZ and the converter overshoot WU. As a function of the slip S, the load request LW and the Lastistwertes List the performance index LZ is formed. This is subsequently corrected with the converter overshoot formed from slip S and load request LW. The converter overshoot WU is for example from a map 1 It can also depend on the actual load value List. The function of the converter overshoot WU and the performance index LZ has different dependencies of slip S, load request LZ and Lastistwert List on to ensure good applicability of the control function. For this purpose, the performance index is formed in such a way that, in particular, the load change effects are represented as dependent on slip. At full slip (slip = 1), by definition, the key performance indicator 1 reached.

The converter overshoot is designed in such a way that the influence of the load range (eg partial load or full load) is also shown depending on the slip. The design takes place in such a way that, in the case of zero slip, the influence of the converter overshoot disappears, and thus increases 1 becomes. The further vote of the static behavior change is made so that the full load contributes more to opening the clutch and in the opposite case, a tendency against zero load, a more direct behavior is generated. This has immediate consequences on the type of Einkuppelcharakteristik, which is therefore decidedly controllable.

Of the Correction value K is multiplied by the precontrol value V and added to the Setpoint of coupling position Y calculated. The clutch is going through a corresponding, preferably electrically or hydraulically actuated actuator according to the reference variable (setpoint Y). This operation can be controlled or over made a position control loop.

2 shows in a block diagram the preferred embodiment of the slip calculation. In this case, the difference between the engine speed N _motor and the transmission speed N _{gear is} formed in a block DIFF. Furthermore, in block MAX, the maximum value of the speed (either transmission or engine speed) is selected. The following block DIV is followed by the speed difference and the maximum value of the speed as an input quantity and a normalization to the respectively determined speed (S = speed difference / (MAX (motor speed, gear speed)) ,

1

Function / map converter overshoot

2

Function / map performance factor

3

Function V = f (N _motor )

N _engine

rotation speed

^N gearbox

transmission

S

slippage

LW

Last wish

Y

Reference variable (nominal clutch torque)

V

pilot value

K

correction value

LZ

performance factor

WU

converter overshoot

ruse

Lastistwert

DIFF

difference images

DIV

Division block

MAX

maximum selection

Claims (7)

Method for controlling an automated clutch, in which the input variables engine speed (N _motor ) and slip (S) between the engine and transmission are used to form a command variable (Y) for the position of the clutch, characterized in that from the engine speed (N _motor ), a pre-control value (V) for the coupling position is formed and this is subsequently applied to a correction value (K), which is dependent on at least the sizes slip (S) between the engine output and transmission, a load request (LW) and a Lastistwert (List) , A method according to claim 1, characterized in that the correction value (K) for the precontrol value (V) formed from engine speed (N _motor ) and clutch position is formed such that at least as a function of slip (S), the load request (LW) and the Lastistwertes (List) a performance index (LZ) and at least from slip (S) and load request (LW) a converter overshoot (WU) is formed, wherein the mapping of the input variables slip (S) and load request (LW) on the performance index of the figure the converter overshoot (WU) is different. Method according to one of the preceding claims, characterized characterized in that the load request (LW) at least from the evaluation the load position transmitter is formed. Method according to one of the preceding claims, characterized characterized in that the load request (LW) representing Evaluation of the load position transmitter by recording its position and / or position change and / or the speed of the position change when operating the Laststellungsgebers is formed. Method according to one of the preceding claims, characterized characterized in that slip (S) between engine output and transmission calculated on the basis of speed measurement values or based on a Model is determined. Method according to one of the preceding claims, characterized characterized in that the slip (S) as a normalized slip value is calculated by the difference of the speed of transmission and Engine by the respective maximum speed (either gearbox or engine speed) is divided. Method according to one of the preceding claims, characterized characterized in that the reference variable (Y) for the position the clutch is the nominal clutch torque.