BE1025861B1 - DRIVER FOR A COUPLING IN A DRIVE LINE AND METHOD FOR DRIVING A COUPLING IN A DRIVE LINE AND A DRIVE LINE CONTAINING THE DRIVING EQUIPMENT - Google Patents

Abstract

A method is provided for controlling a link in a transmission system. The coupling is controllable with a control signal to selectively assume one of a disconnected operational mode, a controlled slipping operational mode, and a locked operational mode. The method comprises: generating a control signal with a feedback control component that holds the coupling in a stable, slipping operational mode; determining at least a first representative value of the control signal and a second representative value of a transmission fluid temperature prevailing in the coupling while the coupling is kept in the stable, slipping operational mode; generating with a open-loop control component a control signal that holds the link in the locked operational mode, the control signal provided by the open-loop control component being at least dependent on the determined first and second representative values.

Description

Control device for a clutch in a drive line and method for controlling a clutch in a drive line as well as a drive line comprising the control device

BACKGROUND

The present invention relates to a control device for a power train.

The present invention further relates to a method for driving a power train.

The present invention further relates to a power train comprising the control device.

A powertrain in a continuously variable transmission usually includes a torque converter / locking clutch (TC / LUC), a forward-neutral reverse clutch (DNR) and a variator. The variator is usually designed as a transmission belt that mechanically couples two pulleys. In normal operation, all elements of the powertrain preferably operate in a non-skid operational mode, since slip would entail energy losses and thereby adversely affect fuel consumption. Slipping of the variator must in particular be avoided, as this leads to wear of the transmission belt and / or the pulleys. This can be achieved through high clamping levels. On the other hand, clamping levels, in particular a clamping level of the transmission belt, should not be set too high, as this would mean that an unnecessarily high control current is supplied by the charging system to maintain this high clamping level, which is also unfavorable for fuel consumption. Additionally, increasing the clamp level above a level required for slip-free operation of the variator tends to increase transmission losses of the variator. This can also cause increased wear of the variator due to increased friction. In addition, it must be taken into account

BE2017 / 6037 that driving conditions can suddenly change, for example due to road damage or rapid braking of the vehicle. To prevent the variator from slipping in such situations, a LUC torque torque capacity must be set to a value lower than a torque torque capacity of the variator. This achieves that in the case of an unexpectedly high torque to be transmitted, the TC / LUC acts as a fuse that absorbs the unexpected torque by slipping, thereby avoiding slipping of the variator. The LUC, usually designed as a fluid coupling, is capable of maintaining a continuous slipping operational mode without damage. The reaction characteristics of elements in the powertrain also depend on their operating temperature. These can vary greatly depending on the time that has elapsed since the vehicle was activated. For the couplings in particular, this depends strongly on their operational mode. In a slipping operational mode, the operational temperature increases sharply as a result of energy dissipation. The reaction characteristics of a coupling can also depend on other circumstances. In addition, the reaction characteristics change over time due to wear during use.

RESUME

It is a first object to provide a control device that allows good control of a clutch, taking into account temperature variations and changes in its characteristics over the lifetime.

It is a second goal to provide a powertrain with the improved control device.

It is a second object to provide a method that is arranged to drive a power train in this way.

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In accordance with said first purpose, a control device is provided according to claim 1. The control device according to this claim is configured to control a coupling in a transmission system, for example a locking coupling as used in a torque converter locking coupling assembly or a coupling which is used in a forward neutral-reverse DNR unit. The coupling is controllable with a control signal from the control device to selectively assume one of a disconnected operational mode, a controlled slipping operational mode and a locked operational mode. The control device comprises an open-loop control with an emulation module and an update module to update the emulation module.

The open-loop control determines a control signal to control the coupling on the basis of estimated reaction characteristics of the coupling, for example on the basis of factory specifications. The control device also comprises a feedback control to provide a control signal component for controlling the coupling based on a sensed reaction of the coupling. The observed reaction may include, for example, a slip speed of the coupling. The feedback control can further base its response on derived variables such as an estimated value of a transmitted torque.

It is noted that the feedback control (also referred to as closed loop control) and the feed forward control (also referred to as open loop control) can share certain components. The feedback control and the feed forward control can, for example, share an amplifier to provide a control signal of sufficient strength. As another example, the feedback control and the feed forward control may share a selection element that selects a signal from a specific feedback element or a specific feed forward element. Accordingly, the feedback control and the feed forward control can also be considered as one and the same control, being in a feedback configuration

BE2017 / 6037 (closed loop configuration) and a feed forward configuration (open loop configuration) respectively. Further, in the feedback configuration, the control signal may be composed by superposition of a feed forward-based component and a feedback-based component.

The control device has at least a first control mode in which the feedback control is capable of generating a control signal that holds the coupling in a stable, slipping operational mode according to predetermined specifications, for example a mode in which a difference between the input rotation speed and the output rotation speed becomes constant. value, or where a ratio between the input rotation speed and the output rotation speed is kept at a constant value. In this stable slipping operational mode, the control device determines at least a first representative value of the control signal with which it maintains that operational mode and also determines a second representative value of a transmission fluid temperature prevailing in the coupling.

The control device uses the representative feedback signal value and the one or more respective representative state values such as the representative value of the transmission fluid temperature to update the emulation module.

The control device further has at least a second control mode in which the feedback control is switched off and wherein the open-loop control generates a control signal which keeps the coupling in the locked operational mode, the control signal being at least dependent on the determined first and second representative values. I.e. the control signal has a value that is dependent on an emulation signal value of an emulation signal generated by the updated emulation module depending on a current value of said one or more coupling state signals.

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In one embodiment of the control device, the feedback control comprises an integrating control component and the representative feedback signal value is determined with the integrating control component. This has the advantage that the value of the output signal supplied by the integrating control component is directly available as an average value representative of the feedback signal value.

In one embodiment, the emulation module is updated in the first control mode to reduce a difference between the characteristic feedback control signal value and a value of the emulation signal associated by the emulation module with the one or more respective representative state values. The associated value is the value of the emulation signal generated by the emulation module based on the respective representative state values. I.e. this is the value that would be required according to the current state of the emulation model as implemented in the emulation module to obtain the controlled slipping operational mode. This may be a value of the control signal to set the clutch in the controlled slipping operational mode or may be a value with which another signal must be changed to obtain the value of the control signal that the clutch is expected to be in the controlled Slipping operational mode is controlled.

The characteristic feedback control signal value indicates the signal value of the control signal for which the controlled slipping operational mode was actually observed or the signal value to be added to the other signal to obtain the value of the control signal for which controlled slipping operational mode was actually observed.

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In one embodiment, the difference is partially reduced during the update. I.e. updating is done in a conservative manner so that fluctuations in the observed signals do not result in an unstable behavior of the controlled coupling.

In a second aspect, an improved drive line is provided for use in a continuously variable transmission system that includes a torque torque converter / lock clutch (TC / LUC), a forward-neutral reverse clutch (DNR), and a variator. The improved drive line may comprise an embodiment of the control device as defined in the claims for controlling the locking coupling and / or an embodiment of the control device as defined in the claims for the DNR coupling.

According to a third aspect, a method is provided for controlling a clutch in a transmission system, wherein the clutch is controllable with a control signal to selectively adopt one of a disconnected operational mode, a controlled slipping operational mode, and a locked operational mode, wherein the method comprises:

generating a feedback control signal with a closed-loop control that holds the coupling in a stable, slipping operational mode based on a sensed reaction of the coupling;

determining a representative control signal value of the feedback control signal with which the coupling is maintained in the stable, slipping operational mode, as well as one or more respective representative state values for one or more coupling state signals indicative of a state of the coupling;

updating an emulation model that is indicative of estimated reaction characteristics of the coupling based on the determined one

BE2017 / 6037 representative control signal value and the one or more respective representative state values;

generating, in an open-loop control mode, an open-loop control signal, using the updated emulation model, as a function of respective actual values of the one or more clutch state signals to keep the clutch in its locked operational mode.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects are described in more detail with reference to the drawings. In there:

FIG. 1 schematically shows a drive line in a vehicle;

FIG. 2 shows aspects of a control device in more detail;

FIG. 3A illustrates an embodiment of the control device in a first control mode;

FIG. 3B illustrates the control device embodiment in a second control mode;

FIG. 4 illustrates a first embodiment of a method for controlling a link;

FIG. 5A-5E shows various signals and state indicators during execution of the first embodiment of the method;

FIG. 6A illustrates another embodiment of the control device in a first control mode;

FIG. 6B illustrates the other embodiment of the control device in a second control mode;

FIG. 7 illustrates a second embodiment of a method for controlling a link;

FIG. 8A-8F displays various signals and state indicators during execution of the first embodiment of the method.

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DETAILED DESCRIPTION OF EXEMPLARY EXAMPLES

FIG. 1 schematically shows a power train in a vehicle for transferring power from a power source 10, such as a combustion engine or an electric motor, to wheels 70 of the vehicle. The drive line as shown in FIG. 1 comprises a torque converter / locking coupling (TC / LUC) 20, a forward-neutral-reverse coupling (DNR), a variator 40, a fixed transmission 50 and a differential 60. The TC / LUC 20 couples an output shaft of the power source 10 to the DNR 30, with a controllable slip value and torque torque ratio, i.e. the ratio between the transmitted torque torque at the output and the torque torque received at the input of the power source 10. The DNR coupling 30 provides a coupling between the TC / LUC 20 and the variator 40. The DNR coupling 30 may be controllable to select an operational mode from a forward driving mode D corresponding to driving the vehicle in a forward direction, a reverse operational mode R, in which the vehicle is driven in reverse and a neutral operational mode in which it keeps the variator 40 disconnected from the TC / LUC 20. The variator 40 transfers the power supplied by the DNR coupling 30 via the fixed transmission 50 and the differential 60 to the wheels 70, with a transmission ratio that can be selected from a continuous range.

In the illustrated embodiment, a setting or operating mode of the TC / LUC 20, DNR 30 and variator 40 clutch is determined by hydraulic signals, i.e., a pressure of a hydraulic fluid. The hydraulic signals are generated by a hydraulic control unit (HCU) 80, which is supplied with a supply current P80 by a pump 85. In the embodiment shown, the operational mode of the TC / LUC 20 is controlled by hydraulic pressure P20, the operational mode of the DNR link 30 is controlled by

BE2017 / 6037 hydraulic pressures P32 and the operational mode of the variator is set by hydraulic pressures P41 and P42. To this end, a hydraulic control unit 80 is provided which in turn is controlled by a transmission control unit (TCU) 100. Alternatively, the operational mode of the different drive train elements can be controlled by electrical signals, for example with the aid of electromagnetic control elements. The TCU 100 is further coupled, e.g. via a bus, here a CAN bus 95, to a motor control unit 90. The TCU is further configured to receive input signals from different inputs, such as a turbine speed signal (the output rotational speed of the TC / LUC), a rotational speed of the primary pulley, corresponding with the DNR output speed, a rotational speed of the secondary pulley at the output of the variator 40, a pressure exerted on the secondary pulley and an oil reservoir temperature. Other input signals, for example from an accelerator pedal, a brake pedal (not shown) and sensor elements, e.g. speed sensors, temperature sensors, torque torque sensors and the like (not shown) can be received and monitored by the motor control unit 90 and transmitted to the TCU 100 via the CAN bus 95.

FIG. 2 schematically shows a control device 100 comprising a control CCL for controlling a clutch CL in a transmission system. The CCL control can be configured as an open-loop control and as a closed-loop control. The clutch CL is controllable with a control signal Pset to selectively assume one of a disconnected operational mode, a controlled slipping operational mode and a locked operational mode. In practice, a hydraulic system is present which converts the control signal, which is usually a low-energy signal, to a signal capable of operating the clutch, for example, as an electrical signal that operates the clutch through electromagnetic forces, or a

BE2017 / 6037 hydraulic pressure that causes a hydraulic actuator to operate the clutch. In other embodiments, an amplifier may be provided which amplifies the control signal and which uses the amplified control signal to generate a hydraulic pressure to operate the clutch. In order to better explain the essential characteristics of the current management, these details are ignored here. For now it is only essential to state that the clutch CL responds to the control signal Pset, and that the reaction characteristics may change over time due to wear of the clutch and also depend on an operating temperature TCL of the clutch, in particular a operating temperature of a hydraulic fluid contained therein.

As shown in FIG. 2, the control CCL comprises an open-loop control OLC for determining a control signal component Pf for controlling the coupling CL on the basis of estimated reaction characteristics of the coupling. The reaction characteristics can be estimated based on factory specifications and the prevailing temperature of the coupling. The open-loop control OLC, that is, the control CCL configured in an open-loop control configuration, comprises an emulation module 124 which generates the control signal component Pf based on an input control signal SOLC from the main control 110 and an input signal indicative of an actual TCL temperature of the coupling.

The control CCL also includes a feedback control CLC, i.e., is configurable as a feedback control, to provide a feedback control signal component Pc for driving the coupling based on a sensed reaction of the coupling CL. In the illustrated embodiment, the observed response is a slip rate ns, as determined by a slip detector 116. The feedback control CLC further comprises a comparator 111 for comparing a required response, e.g. a specified slip value, with

BE2017 / 6037 the observed reaction and to provide an error signal indicative of the difference. The feedback control CLC further comprises a control signal generator 112 to generate a feedback control signal component Pc based on the error signal e. The control signal generator 112 may, for example, comprise one or more of a proportional component, an integrating component and a differentiating component.

The control CCL further comprises a combination component 113 which, depending on a control signal S113 from the main control 110, the feedback control signal component Pc, the open loop control signal component Pf or a combination thereof can select as the control signal Pset to be supplied to the coupling. A combination of control signal components Pc and Pf can for example be a (weighted) sum or a product of these signal components.

In the illustrated embodiment, the main driver 110 is also provided to control other transmission system components T10, T40, T30, with respective signals S10, S40, S30 being exchanged. The other components of the transmission system may, for example, comprise the motor 10, the variator 40 and another clutch. For example, if the clutch CL is the DNR clutch 30, the other clutch to be controlled may be the locking clutch in the torque torque converter and vice versa. The main controller 110 is responsible for proper coordination on the way in which the various components of the transmission system are controlled. The main control device 110 may, for example, control the transmission system such that the variator always has the highest torque torque capacity, so that sudden torque variations, e.g. by bumps in the road, are absorbed by a coupling, so that slip of the variator is avoided.

The control CCL has at least a first operational mode in which the feedback control CLC is capable of generating a control signal Pc that links CL in a stable, slipping operational

BE2017 / 6037 mode maintains. A stable slipping operational mode is a slipping operational mode in which the clutch transmits an at least substantially constant torque with an at least substantially constant slipping speed. This may, for example, be the case where an input of the clutch rotates at a constant speed, and the output of the clutch does not rotate, but exerts a predetermined torsional torque, e.g. at a standstill of a vehicle using the transmission system. In another example, the output of the clutch turns but with a lower rotational speed than the input while transmitting a substantially constant torque to keep the vehicle at a constant speed or to accelerate at a constant speed. It is noted that small variations are permissible, for example variations in the transmitted torque and in the slip speed that are no greater than 20% in a time interval of 20 ms.

While the feedback control CLC maintains the clutch CL in the stable, slipping operational mode, the control determines a first representative value of the control signal Pc with which it maintains this operational mode. The first representative value of the control signal Pc can be, for example, the stabilized value of the control signal, for example the output provided by an integrator component of the control signal generator 112. The control signal can be considered sufficiently stabilized if variations therein are smaller than a predetermined threshold value , for example based on an estimated noise level, for example a slip value corresponding to slip-free operation or a predetermined minimum amount of slip. If an integrator component is absent, this can be an average value. In an alternative embodiment, a representative value before stabilization can be estimated based on the estimated end value, wherein the control signal P is expected to be stabilized, taking into account a value determined by the elements in the closed loop.

BE2017 / 6037 time constant. A value of the control signal can be determined, for example, at the expiration of a predetermined time interval, for example a time interval with a duration of 2 or 3 times that time constant. Although the feedback signal component may still exhibit variations that exceed the noise level, the determined value can be used at that time to estimate the value at which the control signal will stabilize.

The controller determines a second representative value of a transmission fluid temperature TCL in the coupling. Typically, the transmission fluid temperature TCL will rise during this operational mode due to energy dissipation in the clutch. For example, an average value of the transmission fluid temperature TCL during this first control mode of the control may be the representative value. Alternatively, the representative value may be a value of the transmission fluid temperature TCL midway through the first control mode, or it may be based on a measurement of the transmission fluid temperature at a different time, which is corrected for changes due to energy dissipation.

The control CCL further has a second control mode in which the feedback control CLC is switched off and in which the open-loop control OLC generates a control signal Pf which maintains the coupling in the locked operational mode, the control signal depending at least on the determined first and second representative values. This functionality is schematically indicated by update module 120 to update the emulation module 124 based on the determined representative values.

For example, the open-loop control signal generator 124 may include a prediction signal generator component that generates a prediction component based on specifications provided by the coupling manufacturer and an emulation module that provides a

BE2017 / 6037 adaptation to the prediction component based on input from the update module 120.

A first embodiment is described in more detail with reference to FIG. 3A and 3B. In the embodiment shown in FIG. 3A, the clutch CL is a DNR clutch 30. In the illustrated embodiment, the clutch CL is illustrated as a unit that further includes a hydraulic control system that operates the clutch 30 in response to the control signal Pset. In the illustrated embodiment, the open-loop control signal generator 124 is shown schematically as a prediction signal component PKp. It can receive the value for the prediction signal component PKp from an external source as shown in the drawing, or generate this signal internally. In this example, the signal PKp specifies the value of the control signal Pset which is expected to cause the DNR coupling to work at the kiss point in a new coupling state and at a reference temperature. At the kiss point of the DNR coupling, it transfers a layer of 0 different torque torque. This facilitates acceleration of the vehicle from a standstill. For example, the torque torque transmitted in that operational mode of the coupling can be in the range of 1 to 10 Nm. However, the actual value of the control signal depends on the temperature of the coupling, referred to as Toil, and furthermore, the dependence changes during the lifetime of the coupling 30. The open-loop control signal generator 124 further comprises an emulation module 126, to apply the prediction signal PKp to obtain the open-loop control component PKp, adp. Update module 120 regularly adjusts the characteristics of this emulation module 126 to account for changes in this dependency.

For example, the emulation module 126 may include a look-up table that specifies a value for the adjustment signal Padp for each temperature range. For example, each temperature range can be a fixed one

BE2017 / 6037 have a range of 1-10 degrees, for example from 0 to 10, from 10 to 20, etc. Alternatively, temperature ranges can have different sizes, for example larger temperature ranges can be used where the reaction of the coupling is less dependent on the temperature. In another embodiment, the value for Padp is expressed as a mathematical function of the temperature value Toil, wherein the parameters of this function, for example a spline, are adjusted to meet observed characteristics.

A working method is now described in more detail with reference to FIG. 4 and FIG. 5A-5E as well as FIG. 3A, 3B. FIG. 4 schematically steps of the method and illustrate FIG. 5A-5E signals occurring in the controlled transmission system as follows:

FIG. 5A shows a binary signal that specifies whether or not (true / false) the calibration procedure can be initiated.

FIG. 5B shows a (physical) operational mode of the DNR link. FIG. 5C shows a feedback control signal component, here the integrator component P1 of a PID control.

FIG. 5D shows Padp contribution from the emulation module 126.

FIG. 5E shows the temperature Toil of the hydraulic transmission fluid in the coupling 30.

FIG. 4 shows a verification step S0 in which it is verified whether or not the correct conditions exist to perform a calibration procedure, i.e. a procedure in which the emulation module 126 or an emulation model used to control the coupling is updated. In this step, for example, it can be verified that the main driver 110 has controlled the transmission in a non-neutral state. In this state the vehicle is stationary, with the output shaft of the DNR clutch 30 in a non-rotating state and the input shaft of the DNR clutch 30 driven by the engine at a zero position

BE2017 / 6037 different rotational speed of the motor 10 in a stationary operating state.

FIG. 5A, 5B show that this condition is not (yet) met at time t0, since the DNR link 30 is in its decoupled operating mode. It can also be verified whether a predetermined distance has been covered since an earlier implementation of this method. Alternatively, this requirement can be ignored if deviations in the transmission system are detected. In other embodiments, the method can be performed each time at a standstill regardless of the distance traveled. At the time t1, the DNR clutch is stopped with the vehicle in a slipping operational mode, so that the rotational speed of the output shaft of the DNR clutch is still 0. In the neutral operational mode, the main controller 110 is configured to maintain the clutch in the TC / LUC assembly in a fully disconnected operational mode. In this operational mode, only a weak mechanical coupling is provided by the torque coupling converter in the TCLUC assembly.

At this time t1, it is determined that the required conditions are met in step S0, and the feedback control CLC is activated in step S1 to generate a control signal Pc which holds the clutch 30 in the stable, slipping operational mode in which the specified minimum torque torque, for example in the range of 1 to 10 Nm, is transferred to the output of the DNR coupling 30. The control mode of the control in this step is schematically shown in FIG. 3B. In the example shown, the feedback control CLC only provides the correction of the predicted value needed to obtain the output signal Pset that is required to keep the coupling in this operational mode. In other embodiments, as shown in FIG. 3B, the open-loop component 124 can also provide the matching component Padp. In that case, the feedback control CLC provides the correction signal Pc to it

BE2017 / 6037 signal PKp, adp to correct, for reaching kiss point, as shown in FIG. 5C. After a predetermined time interval, at time t2, the correction signal Pc is stabilized, and a representative value C1 thereof is estimated in step S2. A representative value is also referred to as Toil *, determined from the temperature of the hydraulic transmission fluid. This can take place in a time interval t2-t3, to determine an average value of the feedback control signal component and an average value of the temperature.

In step S3, the update module 120 updates the emulation module 126.

For example, by updating the look-up table value for the Padp signal for the temperature range relevant to the determined representative temperature To 1 * by replacing a new look-up table value determined by the representative value CI of the correction signal. For example, if the representative value Toil * for the temperature is 73 degrees C, the value of the look-up table is updated for the range within which this temperature falls. For example, the previous value in the look-up table can be replaced with the representative value for the control signal, but alternatively, it can be replaced with a replacement value that is a linear combination of the previous value and the representative value. Alternatively, if the emulation module 126 calculates its output signal as a parametric function of the actual temperature value, the update module 120 can update the emulation module 126 by modifying the function parameters.

S4 in FIG. 4 is a waiting step in which a change of the operational mode of coupling from slipping operational mode to disconnected operational mode or from a slipping operational mode to closed operational mode is monitored.

If one of these operational mode changes is detected at time t4, the link 30 is driven by the

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OLC with open-loop control using the updated emulation module 120.

FIG. 6A shows a second embodiment, wherein the coupling to be driven is a locking coupling in a torque coupling converter. As in the embodiment of FIG. 3A, the clutch CL is illustrated as a unit that further comprises a hydraulic control system that operates the clutch 20 in response to the control signal Pset. Alternatively, another control system, such as an electromechanical control system, may be used. As in the embodiment of FIG. 3A, the operation of the clutch 20 is dependent on its operating temperature. As a further complication, it is a requirement that the torque Mluc to be transmitted must be controllable. In the embodiment shown, the open-loop control OLC comprises a prediction signal generator PRD which generates a prediction signal Pf, for example based on manufacturer specifications for the new product when operating at a reference temperature. The prediction signal generator PRD generates the prediction signal Pf by using input signals Mref and ns, ref, which are supplied, for example, by the main controller 110. The generated prediction signal Pf indicates the value that according to these specifications drives the coupling 20 to an operational mode assuming that it is capable of transmitting a torque Mref with a slip value ns, ref. The emulation module 126 generates the emulation signal Padp, which adjusts the prediction signal Pf to obtain the control signal Pset as a function of the transmitted torque torque Mluc and the temperature Tluc actually prevailing in the coupling. For example, the emulation module 126 may include a look-up table that specifies a value for the matching signal Padp for each combination of a temperature range and a torque torque range. Each temperature range may, for example, have a fixed range of 1-10 degrees, for example from 0 to 10, from 10 to 20, etc. Otherwise

BE2017 / 6037 temperature ranges have different sizes, for example larger temperature ranges can be used where the reaction of the coupling is less temperature dependent. Similarly, the torque torque ranges used may correspond to one another or may be of different sizes depending on the extent to which the required adjustment signal depends on the transmitted torque torque. In another embodiment, the value for Padp is expressed as a mathematical function of the temperature value Toil and the transmitted torque torque Mluc, wherein the parameters of this function, for example a spline, are adjusted to satisfy observed characteristics.

A method according to this embodiment is now described in more detail with reference to FIG. 7 and FIG. 8A-8F as well as FIG. 6A, 6B. FIG. 7 schematically steps of the method and shows FIG. 8A-8F signals occurring in the controlled transmission system as follows:

FIG. 8A shows a binary signal that specifies whether or not (true / false) the calibration procedure can be initiated.

FIG. 8B shows a (physical) operational mode of the locking coupling.

FIG. 8C shows a feedback control signal component, here the integrator component P1 of a PID control.

FIG. 8D shows Padp contribution from the emulation module 126.

FIG. 8E shows the torque torque transmitted by the coupling.

FIG. 8F shows the temperature Tluc of the hydraulic transmission fluid in the coupling 30.

In FIG. 7, a verification step S10 is shown, in which it is verified whether or not the correct conditions apply to perform a calibration procedure. In this step, for example, it can be verified that the transmission system operates under stationary driving conditions, such that the coupling 20 transmits an at least substantially constant torque at a substantially constant

BE2017 / 6037 rotation speed. This is the case, for example, if the vehicle is in a cruise control drive mode. It may also be possible to carry out the procedure if the vehicle is in a constant moderate acceleration drive mode while maintaining the transmitted torque torque at a substantially constant level. As long as the variations in the transmitted torque and the rotational speed remain within predetermined limits, e.g. do not deviate more than 20% from their average value, it is possible to complete the procedure successfully. It is also possible to start the procedure without a prior condition, but this has the disadvantage that there is a high risk that the procedure will not be successful. It can also be verified whether a predetermined distance has been covered, or a predetermined period of time has elapsed since an earlier implementation of this method. Otherwise, this requirement can be ignored if deviations in the transmission system are detected. As shown in FIG. 8A, at the time t10, this condition is not yet satisfied, since it is detected that the transmitted torque torque exhibits variations that exceed a predetermined limit.

In a subsequent step S11A, S11B, initiated at t11, a descending control signal Pramp is provided to effect a gradual transition of the clutch 20 from a locked operational mode to a slipping operational mode where the LUC transmits a torque torque of predetermined value with a predetermined amount of slip. This is schematically illustrated in FIG. 6B. In this operational mode, the difference between the input rotation speed and the output rotation speed is kept at a constant value, for example a value in the range of 10 to 100 rpm, for example approximately 30 rpm.

As soon as this state is detected, feedback control is enabled in step S12 to generate a control signal that holds the clutch in a stable, slipping operational mode. In a

BE2017 / 6037 exemplary embodiment, the operation of the clutch 20 is considered stabilized in the specified slipping operational mode if the variance of the feedback control signal component pc within a predetermined time interval is less than a threshold value. For example, it may be required that the difference between a highest and a lowest value of the feedback control signal component pc is less than 20% of an average value in the specified time interval, e.g. a time interval of 20 ms. In this example, it is detected at time t14 that the feedback control signal component pc, here pi, remained within specified limits during the specified time window. Assuming that a PID or PI driver is used as the feedback control signal generator 112, the feedback signal component will be equal to the signal from the integrator component pI.

In one embodiment, step S12 may immediately follow step S10 if it is determined that the conditions set in S10 are met. However, this can entail the risk of a noticeable and audible transition from the clutch 20 from its locked operational mode to its slipping operational mode, which causes a reduced driving comfort. In an alternative embodiment, a transition between step S10 and step S12 can be provided through a phase in which the feedback control is immediately released, but where the set point for the slip rate ns, ref is gradually increased from zero slip to the stably slipping operational mode.

As soon as it is determined at time t14 that the feedback control signal is stabilized, in step S13, a representative value c1 of the control signal PC is determined. This may in practice be the output of the integrator component in the control signal generator 112 as determined at the time t14. A representative value Tluc * is also determined for the temperature Tluc of the coupling 20, e.g. a representative value

BE2017 / 6037 for the temperature Toil of the hydraulic fluid used therein. Typically, the transmission fluid temperature Toil will rise during this operational mode of the clutch due to energy dissipation in the clutch. For example, an average value of the transmission fluid temperature TCL during this first control mode of the control may be the representative value. Alternatively, the representative value may be a value of the transmission fluid temperature TCL halfway the time window preceding the time t14 at which stable operation was determined, or it may be based on a measurement of the transmission fluid temperature at another time, correcting for changes as a result of energy dissipation. Furthermore, a representative value Mluc * of the torque is determined in the stably slipping operational mode which is maintained in the specified time window preceding t14.

The representative values c1, Tluc * and Mluc * are used in step S14 to determine updated settings for the emulation module 126. To this end, the update module 120 may identify an entry in a look-up table maintained in the emulation module 126 corresponding to the respective representative values Tluc * and Mluc * for the coupling temperature and the transmitted torque torque and the value for that input in the table replaced by the representative value cI for the feedback control signal component.

Alternatively, update module 120 may replace the old value for that input with a value determined as a weighted average of the old value and the representative value.

It is noted that an entry in a look-up table maintained in the emulation module 126 corresponds to the representative values Tluc * and Mluc * if the input has limits for the temperature and the transmitted torque that contains this representative value. In yet another embodiment wherein the value of the

BE2017 / 6037 adjustment signal component Padp is calculated as a parametric function of the value for the transmitted torque torque Mluc and the value of the temperature Tluc, the update module 120 can adjust the parameters of this function to adjust the adjustment signal component Padp in accordance with the representative value cI for the feedback control signal to bring.

In the illustrated embodiment, an update of the settings of the emulation module 126 does not take place immediately. Instead, the link returns to its locked operational mode with its old settings at step t15 at time t15. Instead, the update is postponed to a time t16 where the link assumes a disconnected operational mode. At that time, the new settings are applied in step S16 so that the change in the settings are not noticeable for the driver.

It is noted that exemplary embodiments may be implemented in digital electronic circuits, or in hardware, firmware, and / or software computer or in combinations thereof. While, for example, specific functions can be performed by respective specific functional elements, it is also possible to perform different functions by the same element at different times. Exemplary embodiments may be implemented using a computer program product, for example, a computer program stored in an information carrier, for example, in a machine-readable medium for execution by, or for controlling, the operation of a data processing device, such as a programmable processor, a computer, or a plurality of computers. In an exemplary embodiment, the machine-readable medium may be a non-volatile machine-readable storage medium.

Claims (16)

CONCLUSIONS A control device (100) for controlling a clutch (CL) in a transmission system, the clutch being controllable with a control signal (Pset) to selectively select one of a disconnected operational mode, a controlled slipping operational mode and a locked operational mode wherein the control device comprises an open-loop control (OLC) with an emulation module (126) and an update module (120) for updating the emulation module, the control device further comprising a feedback control (CLC) around a feedback control signal component (Pc) to provide based on a sensed response from the coupling, wherein the control device has at least a first and a second control mode; wherein in the first control mode the feedback control is capable of generating a feedback control signal that maintains the coupling in a stable, slipping operational mode according to predetermined specifications, in which first control mode the control has a representative feedback signal value (cI) of said feedback control signal as well as one or more respective determines representative state values for one or more link state signals; wherein the control device uses the representative feedback signal value and the one or more respective representative state values to update the emulation module, wherein in the second control mode the feedback control is switched off and wherein the open-loop control generates a control signal to activate the coupling in the locked operational mode wherein the control signal has a value that depends on an emulation signal value of an emulation signal generated by the updated emulation module BE2017 / 6037 depending on a current value of said one or more coupling state signals. The control device of claim 1, wherein the feedback control comprises an integrating control component (112) and wherein the representative feedback signal value is determined with the integrating control component. The control device of claim 1, wherein the emulation module (126) is updated in the first control mode to reduce a difference between the characteristic feedback signal value and a value of the emulation signal associated by the emulation module with the one or more respective representative state values and . The control device according to claim 3, wherein the difference is partially reduced. The control device according to any of the preceding claims, wherein the one or more clutch state signals include a temperature signal (Tluc, Toil) indicative of an operational temperature of the clutch and wherein the control in its first control mode has a representative temperature value of said determines the temperature signal and furthermore the control device uses the representative feedback signal value (c1) and the representative temperature value (Toil *) to update the emulation module (126). The control device of claim 5, wherein the clutch is a clutch (30) in a DNR assembly, and wherein the feedback control is configured to maintain an operational mode as a stable, slipping operational mode in which the clutch has an at least substantially constant torque torque. transmits at an essentially constant slip speed at an output rotation speed of the coupling which is equal to zero. BE2017 / 6037 The control device of claim 5, wherein the one or more clutch state signals further include a torque torque signal (Mluc) indicative of a torque torque transmitted by the clutch (20) and wherein the control in its first control mode has a representative value (Mluc * ) of the torque torque signal; wherein the control device uses the representative feedback signal value (cI), the representative temperature value (Tluc *) and the representative torque feedback signal value (Mluc *) to update the emulation module (126). The control device of claim 7, wherein the clutch (CL) is a lock clutch (20), and wherein the feedback control is configured to maintain an operational mode as a stable, slipping operational mode in which the lock clutch transmits an at least substantially constant torque torque. at an at least substantially constant slip speed, wherein the control device is configured to determine, in said stable, slipping operational mode, the representative torque torque value (Mluc *) indicative of the at least substantially constant torque torque. The control device of claim 8, wherein the control device is configured to enable the open loop control to gradually change an operational mode of the clutch from its locked operational mode to a slipping operational mode and then enable the feedback control to maintain the clutch in the stable, slipping operational mode. 10. A powertrain in a continuously variable transmission system with a torque converter / locking clutch (TC / LUC) (20), a forward-neutral reverse clutch (DNR) (30) and a variator (40), the powertrain further comprising a control device according to one of claims 1 to 6 for controlling the DNR coupling (20) and / or a control device according to BE2017 / 6037 one of claims 1-5 and 7-9 for controlling the blocking coupling (30). A method for driving a link in a transmission system, wherein the link is controllable with a control signal for selectively accepting a disconnected operational mode, a controlled slipping operational mode and a locked operational mode, the method comprising: generating in a closed loop control process a feedback control signal that holds the coupling in a stable, slipping operational mode based on an observed reaction of the coupling; determining a representative control signal value of the feedback control signal with which the coupling is maintained in the stable, slipping operational mode and one or more respective representative state values for one or more coupling state signals indicative of a state of the coupling; updating an emulation model indicative of estimated reaction characteristics of the coupling based on the determined representative control signal value and the one or more respective representative state values; in an open-loop control mode, using the updated emulation model to generate an open-loop control signal as a function of respective actual values of the one or more clutch state signals to keep the clutch in its locked operational mode. The method of claim 11, wherein an integration is used in the closed loop control, and wherein the representative control signal value is determined with the integration. BE2017 / 6037 The method according to claim 11 or 12, wherein the coupling is a DNR coupling and wherein the feedback control is arranged to maintain an operational mode as a stable, slipping operational mode, wherein the coupling has an at least substantially constant torque at an at least substantially transmits constant slip speed, an output rotational speed of the link being zero, the one or more link state signals including a temperature signal indicative of an operational temperature of the link, and the determining comprises determining a representative temperature value of the temperature signal ; wherein said updating comprises using the representative control signal value and the representative temperature value to update the emulation module and wherein the updated emulation model is used to generate an open-loop control signal as a function of an actual value of the temperature signal to enable the coupling in its locked operating mode. The method according to claim 11 or 12, wherein the coupling is a locking coupling, and wherein the stable, slipping operational mode is an operational mode wherein the locking coupling transmits an at least substantially constant torque at a substantially constant slipping speed, and wherein the determining comprises determining a representative temperature value of a temperature signal indicative of an operational temperature of the locking coupling and further determining a representative torque torque signal value indicative of the at least substantially constant torque torque; wherein said updating comprises using the representative feedback signal value, the representative temperature value, and the representative torque value to update the emulation module; BE2017 / 6037 and wherein the updated emulation model is used to generate an open-loop control signal as a function of an actual value of the temperature signal and of an actual value of the torque torque signal. 5 The method of claim 11, further comprising an open-loop control mode prior to the closed-loop control mode to gradually change an operational mode of the clutch from its locked mode to a slipping operational mode and then to enable the feedback control component to stable, 10 Slipping operational mode. The method of claim 11, wherein the open-loop control signal to keep the link in the locked operational mode is delayed dependent on the determined representative values by postponing an adjustment of the emulation model until the link is a disconnected operational mode has adopted.