DE112013002043B4 - Method for controlling a wet friction clutch - Google Patents

Abstract

A method for controlling a wet-running friction clutch (106) of a motor vehicle which can be actuated between an open and a closed position, the friction clutch (106) having a pressure plate, a pressure plate which can be axially displaced relative to the pressure plate and a clutch disc which can be clamped between the pressure plate and the pressure plate, the friction clutch ( 106) is controlled based on a clutch characteristic curve (202, 416), characterized in that a clutch drag torque characteristic curve (302) is determined and superimposed on the clutch characteristic curve (202, 416) in order to obtain a modified clutch characteristic curve (204, 408), the clutch drag torque characteristic curve (302) above (314, 316) a touch point position of the clutch characteristic (202, 416) is limited to a maximum value.

Description

The invention relates to a method for controlling a wet-running friction clutch of a motor vehicle that can be actuated between an open and a closed position, the friction clutch having a pressure plate, a pressure plate which can be axially displaced relative to the pressure plate and a clutch disc which can be clamped between the pressure plate and the pressure plate, the friction clutch being based on a Clutch characteristic is checked.

From the German Offenlegungsschrift with the file number DE 10 2011 084 671 A1 a clutch is known, in particular for the drive train of a motor vehicle, comprising a clutch disc which is mounted on a shaft in a bearing and is designed for receiving and transmitting a torque, which has a positioning device for aligning the clutch disc when the clutch is open, the positioning device at least has a first element which is provided on or in the clutch disk at a radial distance from the axis of rotation and exerts or develops a force without contact that counteracts a misalignment of the clutch disk in the bearing when the clutch is open in order to create a structural design of a clutch which can either reduce the drag torque of the clutch disc with the air clearance remaining the same or, conversely, the air clearance with the drag torque remaining the same.

DE 10 2008 014 531 A1 discloses the repeated adaptation of a clutch characteristic, whereby the difference between the target torque and the measured actual torque is determined at predetermined setting positions, whereby the sum of the drag torque and the actual clutch torque is always determined and the clutch characteristic also represents this sum. In addition, it is provided that the measurement is carried out at the predetermined setting positions at positions along the entire coupling travel path.

WO 2011/134 451 A1 discloses a method for adapting a touch point of a clutch in a drive train of a motor vehicle.

The object of the invention is to functionally improve a method mentioned at the beginning. In particular, comfort is to be improved. In particular, vibration excitation should be reduced or prevented. In particular, feedback of modified parameters should be avoided.

The object is achieved by a method having the features according to claim 1.

The object is achieved with a method for controlling a wet-running friction clutch of a motor vehicle that can be actuated between an open and a closed position, the friction clutch having a pressure plate, a pressure plate that can be axially displaced relative to the pressure plate and a clutch disc that can be clamped between the pressure plate and the pressure plate, the Friction clutch is controlled based on a clutch characteristic curve, in which a clutch drag torque characteristic curve is determined and the clutch characteristic curve is superimposed in order to obtain a modified clutch characteristic curve, the clutch drag torque characteristic curve being limited to a maximum value above a touch point position of the clutch characteristic curve.

A wet-running friction clutch can be a friction clutch that is acted upon by a flow of fluid. The flow of liquid can in particular serve to cool the friction clutch. The liquid can be an oil. The fluid can be a gear oil. The friction clutch can be part of a friction clutch device. The friction clutch can be a single clutch. The friction clutch can be part of a double clutch together with a second clutch. A friction clutch can be a single-plate clutch. A friction clutch can be a multi-plate clutch. The friction clutch can be actuated automatically.

The friction clutch can be used for arrangement in a drive train of the motor vehicle. The drive train can have an internal combustion engine. The drive train can have a transmission. The friction clutch can be arranged in the drive train between the internal combustion engine and the transmission. The friction clutch can have an input part. The friction clutch can have an output part. The input part of the friction clutch can be drivably connected to an output shaft of the internal combustion engine. The output part of the friction clutch can be drivably connected to an input shaft of the transmission. The terms “input part” and “output part” refer to a power flow direction starting from the internal combustion engine.

A friction clutch can start from a fully open actuation position, in which there is essentially no power transmission between the input part and the output part, to a completely closed actuation position, in which there is essentially a complete power transmission between the input part and the output part, an increasing one depending on the operation Enable power transmission, power transmission between the input part and the output part taking place in a frictional manner. Conversely, starting from a completely closed actuation position, in which essentially a complete power transmission takes place between the input part and the output part, up to a completely open actuation position, in which essentially no power transmission takes place between the input part and an output part, a decrease in power transmission depending on the actuation be made possible.

The friction clutch can be actuated with the aid of an actuator device. The actuator device can be part of the friction clutch device. The actuator device can serve for the semi-hydraulic control of the friction clutch. The actuator device can have a hydraulic path. The actuator device can have a master cylinder. The actuator device can have a slave cylinder. The slave cylinder can be used to act on the friction clutch. The hydraulic line can be used to transmit power between the master cylinder and the slave cylinder. The actuator device can have an electric motor drive. The drive can serve to act on the master cylinder. The actuator device can have a transmission.

The friction clutch device can have a sensor for determining an actuating position of the friction clutch device. This sensor can be a position sensor. This sensor can be used to determine a set position of the friction clutch. This sensor can be used to determine a set position of the actuator device. The friction clutch device can have a sensor for determining a transmitted torque. This sensor can be a moment sensor. The friction clutch device can have a sensor for determining a slip of the friction clutch. A slip can be a speed difference between the input part and the output part of the friction clutch. The friction clutch device can have a sensor for determining a fluid flow. The friction clutch device can have a sensor for determining a temperature, in particular a liquid.

A tactile point can be relevant when the friction clutch is actuated. The touch point can describe a setting position of the friction clutch device, the friction clutch and / or the actuator device, in which a friction clutch begins to transmit a torque when actuated from an open actuation position in the direction of a closed actuation position. The touch point can describe a setting position of the friction clutch device, the friction clutch and / or the actuator device, in which a friction clutch transmits a predetermined torque. The predetermined torque can be approximately 2-3 Nm, for example. In the present case, the term “touch point” can designate both the touch point as such and a set position of the friction clutch device, the friction clutch and / or the actuator device assigned to the touch point.

The friction clutch device can have a control device. The control device can be a device for controlling and / or regulating. The control device can serve to control the friction clutch device, the friction clutch and / or the actuator device. Controlling can be steering and / or regulating. The control device can serve to carry out the method according to the invention. The control device can have an electrical control device. The control device can have a memory device. The storage device can have a non-volatile, electronic memory, the stored information of which can be electrically deleted or overwritten. The memory device can have an EEPROM. A clutch characteristic can be stored in the memory device. A clutch drag torque characteristic can be stored in the storage device. A setting position of the friction clutch device, the friction clutch and / or the actuator device assigned to the touch point can be storable in the memory device. The control device can have a computing device.

The clutch characteristic can represent a torque transmitted by the friction clutch as a function of an actuating position of the friction clutch device, the friction clutch or the actuator device. The clutch characteristic can be shown in a diagram in which the setting position of the friction clutch device, the friction clutch or the actuator device is plotted on an x-axis and the transmitted torque is plotted on a y-axis.

The clutch drag torque characteristic curve can represent a drag torque of the friction clutch as a function of a setting position of the friction clutch device, the friction clutch or the actuator device. The clutch drag torque characteristic can be shown in a diagram in which the actuating position of the friction clutch device, the friction clutch or the actuator device is plotted on an x-axis and the drag torque is plotted on a y-axis.

A clutch drag torque can result when the pressure plate approaches the pressure plate. A clutch drag torque can occur even before the clutch disc is clamped between the pressure plate and the pressure plate. A clutch drag torque can result from a liquid in the wet-running friction clutch. A clutch drag torque can be influenced by the viscosity of the fluid. A clutch drag torque can be influenced by a temperature of the fluid. A clutch drag torque can be influenced by a flow of the fluid.

The method according to the invention enables the clutch characteristic to be modified, with a modification adapted to a respective clutch drag torque taking place depending on a setting position of the friction clutch device, the friction clutch and / or the actuator device. A comfort is improved. Vibrational excitation is reduced or prevented. A feedback of modified parameters is avoided. A robust solution is provided for taking clutch drag torque into account.

The clutch characteristic curve and the clutch drag torque characteristic curve can have interpolation points that each include an actuator position value, and the actuator position values of the interpolation points of the position-drag torque characteristic curve can correspond to the actuator position values of the interpolation points of the position-torque characteristic curve. The support points can be data points. A support point of the clutch characteristic can include information about a setting position of the friction clutch device, the friction clutch and / or the actuator device and a corresponding torque value. A support point of the clutch drag torque characteristic can include information about a setting position of the friction clutch device, the friction clutch and / or the actuator device and a corresponding drag torque value.

The clutch drag torque characteristic can be determined repeatedly. The clutch drag torque curve can be determined continuously. A clutch drag torque can thus be adapted repeatedly or continuously. The clutch drag torque characteristic curve can be determined taking into account a clutch slip, a fluid flow and / or a fluid temperature. The clutch drag torque characteristic curve can be determined taking into account a setting position value of the friction clutch device, the friction clutch and / or the actuator device. The set position value can be an actual set position value from which a touch point set position value is subtracted.

In summary and in other words, the invention thus results, inter alia, in taking drag torques into account when a clutch is activated in wet clutch / double clutch systems by modifying the clutch characteristic. The drag torque can be determined for different plate distances and this drag torque characteristic can be added to the clutch characteristic. The drag torque can increase from the wide open position to shortly before the touch point, the plate distance at the touch point can be zero. The support points of the drag torque can be identical to those of the clutch characteristic to which the drag torque is added. The drag torque curve can depend on the slip, oil flow and an oil temperature and can be recalculated in each calculation step for different plate distances; for one calculation step, slip, oil flow and oil temperature can be viewed as constant. The coupling characteristic can be shifted to the left by adding.

In particular, optional features of the invention are referred to as “can”. Accordingly, there is in each case one exemplary embodiment of the invention which has the respective feature or features.

Exemplary embodiments of the invention are described in more detail below with reference to figures. Further features and advantages emerge from this description. Specific features of these exemplary embodiments can represent general features of the invention. Features of these exemplary embodiments that are connected to other features can also represent individual features of the invention.

• 1 einen Aufbau eines hydrostatischen Kupplungssystems,
• 2 ein Diagramm mit einer Positions-Moment-Kennlinie,
• 3 ein Diagramm mit einer Positions-Schleppmoment-Kennlinie und
• 4 ein Diagramm zur Struktur einer Moment- und Wegbestimmung.

They show schematically and by way of example:

• 1 a structure of a hydrostatic clutch system,
• 2 a diagram with a position-torque characteristic,
• 3 a diagram with a position-drag torque characteristic and
• 4th a diagram for the structure of a moment and path determination.

1 shows a structure of a hydrostatic clutch system 100 . The coupling system 100 is used to operate one of two clutches of a double clutch, the second clutch is operated accordingly. An electromechanical actuator 102 serves to act on a master cylinder 104 , which presses on an oil column, which in turn is one of the clutch 106 assigned slave cylinder 108 moves and thereby the clutch 106 actuated. The coupling 106 is a directly operated wet clutch.

The coupling 106 has an input part and an output part. The input part has a pressure plate and a pressure plate. The pressure plate is connected to the pressure plate in a rotationally fixed and axially displaceable manner. The output part has a clutch disc. The clutch disc is arranged between the pressure plate and the pressure plate when viewed in the axial direction. When the clutch is actuated 106 the pressure plate is displaced so that a distance between the pressure plate and the pressure plate changes. The coupling 106 is acted upon by a flow of cooling oil, in particular to dissipate heat generated by friction between the pressure plate and the pressure plate on the one hand and the clutch disc on the other. When the pressure plate and the pressure plate approach each other or the clutch disc, the cooling oil flow causes a clutch drag torque. A clutch drag torque occurs even before there is direct contact between the pressure plate and the pressure plate on the one hand and the clutch disc on the other. The clutch drag torque depends not only on the distance between the pressure plate and the pressure plate to one another or to the clutch disc on the cooling oil, in particular on a viscosity, a temperature and / or a flow of the cooling oil.

Between the master cylinder 104 and the slave cylinder 108 is a hydrostatic stretch 110 educated. The master cylinder 104 and the slave cylinder 108 each have different piston areas. This results in a translation of the hydrostatic route 110 . The actuator 102 has an electric motor 112 and a gearbox 114 on. The electric motor is an integrated EC motor. The electric motor 112 has an integrated control unit 116 on. The gear 114 serves to make a rotary movement of the electric motor 112 to convert it into a linear stroke movement. The gear 114 has a gear ratio. The gear 114 is a spindle drive, for example with a planetary roller screw spindle.

The master cylinder 104 has a piston 118 with a comparatively large piston area. The piston area of the master cylinder 104 is arranged radially around the spindle drive so that the overall length is short. The piston 118 is designed as a pulling piston to reduce axial forces in a short flow of force from a housing to the spindle bearing. For volume compensation of the hydrostatic system, a so-called sniffing position is provided when the clutch position is open. In this position the pressure line 120 with a follow-up chamber 122 associated with temperature-related volume changes of the liquid in the hydrostatic path 110 can be balanced.

The electric motor 112 has a rotor with rotation angle detection. For this purpose, a magnetic field from a magnet attached to the spindle is evaluated by an angle sensor attached directly to a circuit board. This solution is precise, space-optimized and nevertheless inexpensive, since, for example, there is no mechanical adjustment between stator and sensor position. The electric motor 112 has an integrated temperature sensor to protect power amplifiers.

The coupling system 100 has a sensor-based overload protection. Reliable function is thus enabled with comparatively little effort and further advantages can be used. A pressure sensor 124 serves as overload protection for the hydrostatic section 110 and for the clutch 106 . The signal from the pressure sensor 124 can also be used for reliable detection of the clutch characteristic even when the gear is disengaged. The hydrostatic route also has a life of its own 110 , for example due to thermal expansion of the fluid, when the clutch is actuated 106 recognized and taken into account by software. For a measurement of a position of the piston 118 is an absolute travel sensor 126 intended. Through the use of the local control device 116 and the arrangement of all sensors close to the board, the sensor system can be implemented cost-effectively, since additional cabling and connection costs are not required

2 shows a diagram 200 with a position-torque characteristic 202 a clutch, like clutch 106 according to 1 . The position-torque characteristic 202 can also be referred to as a clutch curve. In the diagram 200 actuator position values are plotted on an x-axis. The actuator position values are determined using a sensor such as Sensor 126 according to 1 , determined. In the diagram 200 moment values are plotted on a y-axis. The position-torque characteristic 202 has support points which are marked with + in the figure. Position-torque characteristic 202 is in a control unit, such as a control unit 116 according to 1 , saved.

The position-torque characteristic 202 runs from the fully open position of the clutch in the direction of the closed position steadily and smoothly rising. In particular, the position-torque curve runs 202 also in a transition area in which the distance between the pressure plate and the pressure plate to each other or to the clutch disc is so small that a drag torque occurs, and then a direct contact is established between the pressure plate and pressure plate on the one hand and the clutch disc on the other, smoothly increasing.

3 shows a diagram 300 with a position-drag torque characteristic 302 a clutch, like clutch 106 according to 1 . The position-drag torque characteristic 302 can also be referred to as clutch drag torque characteristic. In the diagram 300 actuator position values are plotted on an x-axis. The actuator position values are determined using a sensor such as Sensor 126 according to 1 , determined. In the diagram 300 drag torque values are plotted on a y-axis. The position-drag torque characteristic 302 has support points which are marked with + in the figure. The actuator position values of the interpolation points of the position-drag torque characteristic 302 correspond to the actuator position values of the interpolation points of the position-torque characteristic 202 .

ermittelt, wobei ein nominales Schleppmoment Trq_Dragnom(N_SlipSpeed, L_Liftoff) mit einem öltemperaturabhängigen Faktor K_Vis(T_Oil) und einem ölstromabhängigen Faktor K_Corr(V_Oil) multipliziert wird.The position-drag torque characteristic 302 is made using a control device such as a control device 106 according to 1 , determined. The position-drag torque characteristic 302 is for example according to the function $$Tr{q}_{\mathrm{D.}raG}=Tr{q}_{\mathrm{D.}raGnOm}\left(N_{\mathrm{S.}lip\mathrm{S.}peed},{\mathrm{L.}}_{\mathrm{L.}iftOff}\right)\ast K_{Vis}\left(T_{Oil}\right)\ast K_{\mathrm{C.}Orr}\left({\dot{V}}_{Oil}\right)$$

determined, wherein a nominal drag torque Trq _Dragnom (N _SlipSpeed, L _Liftoff) with an oil temperature dependent factor K _Vis (T _oil) and an oil flow-dependent factor K _Corr (V _oil) is multiplied.

The position-drag torque characteristic 302 runs between the support point 310 and 314 in the section 312 strongly increasing. In the section 312 the clutch is still open, but the clearance between the pressure plate and the clutch disc has been greatly reduced. From the support point 314 a section follows 316 , in which the position-drag torque characteristic 302 runs horizontally. The real drag torque characteristic would be as in section 312 continue to rise sharply, but is limited to a maximum value here. In one section 304 starting from the fully open position of the clutch in the direction of the closed position horizontally at y = 0, the drag torque is set to zero. One reaches between the touch point and the so-called modulation point, z. B. at -3Nm similar path lengths even with an aged clutch system in which the touch point shifts to the right.

The position-drag torque characteristic 302 becomes the position-torque characteristic 202 superimposed. This creates a modified position-torque characteristic 204 which takes the drag torque into account. The modified position-torque characteristic 204 corresponds to the position-torque characteristic 202 but is shifted to the left. Starting from the support point 206 that of the support point 306 corresponds, has the modified position-torque characteristic 204 a section with a linear increase. At a support point 208 that of the support point 310 corresponds, there is a transition to that of the position-torque characteristic with a kink 202 corresponding curve section of the modified position-torque characteristic 204 .

4th shows a diagram 400 for the structure of a moment and path determination. The moment and path is determined in a control unit, such as a control unit 106 according to 1 , carried out. First of all, starting from a clutch path 402 a compensated clutch travel 404 taking into account parameters 406 , such as crosstalk, hysteresis, engine speed, and / or temperature, determined. Based on the compensated clutch travel 404 is based on a modified clutch curve 408 , such as modified position-torque characteristic 204 according to 2 , a clutch torque 410 certainly. The clutch torque 410 is taking into account adaptation parameters 412 as well as other parameters 414 such as slip, temperature and / or power loss. The modified clutch curve 408 is based on a clutch characteristic 416 taking into account parameters 418 , such as slip, an oil flow, oil temperature and / or actuator position minus a touch point position.

List of reference symbols

100

Coupling system

102

Actuator

104

Master cylinder

106

coupling

108

Slave cylinder

110

hydrostatic range

112

Electric motor

114

transmission

116

Control unit

118

piston

120

Pressure line

122

Follow-up chamber

124

Pressure sensor

126

Absolute travel sensor

200

diagram

202

Position-torque characteristic

204

modified position-torque characteristic

206

Support point

208

Support point

300

diagram

302

Position drag torque characteristic

304

section

306

Support point

310

Support point

312

section

314

Support point

316

section

400

diagram

402

Clutch travel

404

compensated clutch travel

406

parameter

408

modified clutch characteristic

410

Clutch torque

412

Adaptation parameters

414

parameter

416

Clutch characteristic

418

parameter

Claims (4)

A method for controlling a wet-running friction clutch (106) of a motor vehicle which can be actuated between an open and a closed position, the friction clutch (106) having a pressure plate, a pressure plate which can be axially displaced relative to the pressure plate and a clutch disc which can be clamped between the pressure plate and the pressure plate, the friction clutch ( 106) is controlled based on a clutch characteristic curve (202, 416), characterized in that a clutch drag torque characteristic curve (302) is determined and superimposed on the clutch characteristic curve (202, 416) in order to obtain a modified clutch characteristic curve (204, 408), the clutch drag torque characteristic curve (302) above (314, 316) a touch point position of the clutch characteristic (202, 416) is limited to a maximum value. Procedure according to Claim 1 , characterized in that the clutch characteristic curve (202, 416) and the clutch drag torque characteristic curve (302) have support points (206, 208, 306, 310, 314), each of which includes an actuator position value, and the actuator position values of the support points (306, 310, 314) of the position-drag torque characteristic curve (302) correspond to the actuator position values of the interpolation points (206, 208) of the position-torque characteristic curve (202). Method according to at least one of the preceding claims, characterized in that the clutch drag torque characteristic curve (302) is determined repeatedly. Method according to at least one of the preceding claims, characterized in that the clutch drag torque characteristic curve (302) is determined taking into account a clutch slip, a fluid flow and / or a fluid temperature.

Images