GB2531297A

GB2531297A - Determining a torque capacity of a clutch of a passenger car

Info

Publication number: GB2531297A
Application number: GB1418248.9A
Authority: GB
Inventors: Hendrik Willem Van Boxtel; Eric Janista; Gianmarco Brunetti; Lorenzo Disaro'
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2014-10-15
Filing date: 2014-10-15
Publication date: 2016-04-20
Anticipated expiration: 2034-10-15
Also published as: GB201418248D0; GB2531297B; DE102014016042A1

Abstract

Torque capacity T(x) of a clutch 1 of a passenger car with respect to a position (x) of the clutch (1), is determined by: determining (S10) a first acceleration (a1) of the car wherein the clutch (1) is in a first position (x1); determining (S50) a second acceleration (22) of the car wherein the clutch (1) is in a second position (x2) different from the first position (x1); and determining (S60) a torque capacity value (T(x2-x1)) with respect to a difference (x2-x1) between the first and second position (x1, x2) on the basis of a difference (a2-a1) between the first and second acceleration (a1, a2). The clutch may be fully engaged in one position and fully disengaged in another position. A factor relating to the engaged gear of the vehicle may also be applied.

Description

Determining a Torque Capacity of a Clutch of a Passenger Car

Description

The present invention refers to a computer program and a method implemented by the computer program and a system for determining a torque capacity of a clutch of a passenger car and to a passenger car comprising such system.

The maximum torque which a clutch can transmit ("torque capacity") between a power unit like a combustion engine and a transmission depends on a position of said clutch like an axial position of a throw-out bearing as can be seen by the just schematic curve depicted in fig. 4: with the position x of the clutch increasing from a fully disengaged clutch at the left side of fig. 4 (xo%) towards a fully engaged clutch at the right side of fig. 4 (xloa%), the torque capacity T(x) increases from 1 = 0 up to an absolute maximum for the fully engaged clutch. In between the clutch can maximally transmit torque 1(x) between I = 0 (x0) and the absolute maximum T(xloo%).

Knowing the torque capacity with respect to a position of the clutch inter a/ia allows to control an electrically operated clutch advantageously, in particular by being able to determine a position of the clutch to be adjusted in order to realize a desired torque, e.g. for a smoother launch or the like.

However, the torque capacity at the same position varies inter ella with temperature, wear, humidity, manufacturing tolerances etc. Thus, an actual torque capacity may differ from a theoretical torque capacity which is used to control an electrically operated clutch. This may result in an inferior performance of the car.

Therefore one object of the present invention is to improve the performance of a passenger car.

Said object is solved in particular by the feature combination of present claim 1. Claims 14, 15 refer to system for executing a computer program and a method implemented by the computer program as described herein and to a passenger car comprising such system respectively, sub-claims refer to advantageous embodiments.

According to one aspect of the present invention a computer program or a method implemented by a computer program for determining a torque capacity T(x) of a clutch of a passenger car with respect to a position x of the clutch comprises the steps: (a) determining a first acceleration of the car wherein the clutch is in a first position; (b) determining a second acceleration of the car wherein the clutch is in a second position different from the first position; and (c) determining a torque capacity value with respect to a difference between the first.

and second position on the basis of a difference between the first and second acceleration.

According to one embodiment the clutch is coupled between a power unit and a transmission of the passenger car. The power unit may comprise an internal combustion engine and/or an electric motor The transmission may be a (fully) manual transmission, a semi-automatic transmission or an automatic transmission. The transmission may comprise two input shafts to be coupled selectively to one output shaft or two output shafts to be coupled selectively to one input shaft in one embodiment.

According to one embodiment the clutch is an electrically operated clutch, in particular comprising an electrically operated actuator for engaging and/or disengaging the clutch. The actuator may comprise an electromotor and/or may be an electromagnetic, hydraulic or pneumatic actuator.

An electrically operated clutch can be controlled in an advantageous way if the torque capacity is known more precisely according to one embodiment. In particular the torque capacity determined as described herein may be advantageously used to determine an adjustment, in particular a displacement of a throw-out bearing and/or a, preferably electrically actuated, actuator engaging and/or disengaging the clutch, with respect to a desired torque, in particular to feedforward or feedback control the clutch. Additionally or alternatively determining the torque capacity can also improve the car's performance in other ways, in particular may be used to diagnose the clutch, for example determine (overly) wear, failure or the like if a determined torque capacity drops out of a predetermined range according to one embodiment.

Accordingly one aspect of the present invention comprises controlling and/or diagnosing a clutch of a passenger car, in particular an electrically operated clutch, on the basis of a torque capacity determined as described herein and/or a means for controlling and/or diagnosing a clutch of a passenger car, in particular an electrically operated clutch, on the basis of a torque capacity determined as described herein.

A position of the clutch as referred herein may in particular depend on or indicate an extent of engagement or disengagement of the clutch respectively. It may be an axial or rotational position of a clutch member whose displacement varies to engage or disengage the clutch. In particular it may be the axial position of a throw-out bearing of the clutch, a distance between friction surfaces of the clutch, a displacement of a mechanically or electrically operated actuator of the clutch or the like.

According to one aspect of the present invention it has been noted that a positive or negative acceleration of the car changes, in particular essentially linear, if torque added to a transmission or drive train coupled to driven wheels of the car by the clutch changes, in particular torque resulting from inertia, friction and the like of a combustion engine and/or a drive train gradually coupled to or decoupled from said driven wheels by the clutch respectively.

For example the car may be sailing with disengaged clutch and non-running combustion engine. If sailing is terminated by engaging the clutch, thereby cranking the combustion engine, this adds additional torque to the drive train which in return decelerates the car more than it would do in sailing mode where only aerodynamic, friction, gravitation and dynamic forces decelerate the car.

Likewise the car (positively) accelerates from standstill if the clutch is being engaged with the power unit running, thus adding accelerating torque to the drive train.

Likewise starting sailing mode may decrease a car's deceleration since the drive train does not need to haul the engine any more.

Additionally it has been found that when the clutch is neither fully engaged nor fully disengaged, i.e. slips, it transmits the maximum torque which the clutch is capable of at this position since the clutch starts to slip upon reaching the maximum torque transmittable at this position, i.e. grade of (dis)engagement of the clutch.

Therefore, determining the deceleration of the car at different positions of the clutch, at least one of which preferably is neither a fully engaged nor fully disengaged position, allows to determine a torque capacity of the clutch for said positions.

A determined acceleration may be positive or negative, in particular with respect to a longitudinal forward direction of the car. Thus, a determined acceleration may in particular be a longitudinal deceleration (slowing down the forward moving car) or (positive) acceleration (increasing the car's longitudinal forward velocity), The acceleration may be determined directly, in particular by an acceleration sensor. In another embodiment the acceleration may be determined indirectly, in particular by a, preferably numerical, differentiation or time derivative of a velocity of the car, in particular at least one driven wheel or shaft of a drive train coupled thereto.

According to one embodiment steps (a) to (c) are reiterated with one or more further pairs of a first and second position of the clutch determining further torque capacity values accordingly. This may advantageously allow to determine a torque capacity with respect to different positions, in particular at a higher resolution with respect to a position.

According to one embodiment the first or second acceleration and position of a preceding sequence of steps (a) to (c) establish a first or second acceleration and position in a successive sequence of steps (a) to (c).

In particular the first acceleration of a, in particular directly, preceding sequence of steps (a) to (c) may be determined also as the first acceleration of a, in particular directly, successive sequence of steps (a) to (c), the first position of the preceding and successive sequence thus being identical while the second position of the preceding and successive sequence differ from one another. Then the torque capacity values indicate absolute values with respect to the (same) first position. In other words if a2 is determined for X2-X1 and a2 is determined for x2-x1, then a2 and a2' indicate absolute values with a(xi) = o as a reference or offset respectively.

Alternatively the second acceleration of a, in particular directly, preceding sequence of steps (a) to (c) may be determined as the first acceleration of a, in particular directly, successive sequence of steps (a) to (c), the second position of the preceding sequence and the first position of the successive sequence thus being identical while the second position of the sequence differ fro-n the first and second position of the preceding sequence. Then the torque capacity values indicate relative values or deltas which can be added up to an absolute torque capacity with respect to position as well. In other words if a2 is determined for X2-Xl and a2' is determined for X2'-X2, then a2 and (a2+a2') indicate absolute values with a(xi) = 0 as a reference or offset respectively since a(x2') = a(x2) + a2'(x2'-x2) approximately.

Thus, a torque capacity (x) of a clutch of a passenger car with respect to a position of the clutch may relate to one or more positions x1 of the clutch, in particular a fully engaged clutch, a fully disengaged clutch and/or one or more positions in between, to corresponding torques or torque values T respectively which the clutch can transmit at most in the respective position. As explained above such torque capacity (x) may be determined from the torque capacity values determined as described herein, in particular either directly from absolute torque capacity values which are determined with respect to one single first or second position (which than yields a reference or offset) or indirectly by relative torque capacity values which are determined with respect to differences between different of said positions.

Pairs ofafirst and second position of the clutch of different sequences may differ infinitesimally from one another, i.e. the sequence may be reiterated continuously while the position of the clutch varies. This may allow for a very precise determination of the torque capacity with respect to the position. In another embodiment, pairs of a first and second position of the clutch of subsequent sequences may differ with discrete steps from one another, i.e. the sequence may be reiterated in discrete steps with respect to position or time. This may allow for a very efficient sampling of the torque capacity with respect to the position. Positions of subsequent sequences may differ for at least 5%, in particular at least 10% of a range between the fully engaged and fully disengaged position according to one embodiment, in particular to allow an advantageous discrete sampling.

According to one embodiment the computer program or a method implemented by the computer program respectively starts with the clutch being fully disengaged, in particular when launching the car or terminating a sailing mode of the car in which the clutch is disengaged, the combustion engine preferably non-running or shut off respectively. The computer program or method respectively may end before or when the clutch is fully engaged. According to another embodiment the computer program or a method implemented by the computer program respectively starts with the clutch being fully engaged, in particular when starting the saling mode of the car. The computer program or method respectively may end before or when the clutch is fully disengaged. According to yet another embodiment the computer program or a method implemented by the computer program respectively starts with the clutch being neither fully disengaged nor fully engaged, in particular creeping.

Accordingly the clutch is fully engaged or disengaged in a first or second position according to one embodiment.

According to one embodiment a torque capacity value is determined for one or more inter-positions between the fully engaged and fully disengaged position of the clutch. As explained before, the clutch transmits maximum torque in such intermediate positions so that it may be advantageous to determine the torque capacity also or only with respect to such intermediate positions.

Accordingly the first and/or second position of one or more, in particular all, sequences of steps (a) to (c) is a position between or different from a position in which the clutch is fully engaged and a position in which the clutch is fully disengaged according to one embodiment.

As already explained above, the computer program or a method implemented by the computer program respectively may be performed when the clutch is adjusted from a fully or more disengaged position towards or into a fully or more engaged position, in particular when terminating a sailing mode, preferably with the internal combustion engine not running, or launching the car, preferably with the internal combustion engine running. Additionally or alternatively, the computer program or a method implemented by the computer program respectively may be performed when the clutch is adjusted from a fully or more engaged position towards or into a fully or more disengaged position, in particular when starting the sailing mode.

Accordingly, the clutch is more engaged or more disengaged in the first position than in the second position of one or more, in particular all, sequences of steps (a) to (c) according to one embodiment.

According to one embodiment the electrically operated clutch is automatically adjusted into the first and/or second position of one or more sequences of steps (a) to (c). According to one embodiment, such adjustment may be determined by a driver assistant system, in particular by a driver assistant system starting or terminating a sailing mode or the like. This advantageously allows to use an engagement or disengagement event of the clutch to determine also the torque capacity. Additionally or alternatively, such adjustment may be determined in order to determine the torque capacity alone, for example in a diagnose mode or the like.

According to one embodiment one or more torque capacity values determined as described herein are stored, in particular in the form of a look-up table or the like. Such stored torque capacity values may preferably be used to control the electrically operated clutch. In particular a look-up table of the stored values may be used to determine a necessary position, in particular adjustment, of the clutch in order to realize a desired torque transmission via said clutch. Additionally or alternatively torque capacity values determined as described herein may be used to correct or adjust a predetermined torque capacity, in particular a basis or theoretical torque capacity.

According to one embodiment the clutch is maintained in the first and/or second position of one or more sequences of steps (a) to (c) for a predetermined time. This * may allow for a more precise determination, in particular reduce inertia effects, signal disturbances and the like.

Additionally or alternatively, the first and/or second determined acceleration and/or position of one or more sequences of steps (a) to (c) may be smoothened according to one embodiment, in particular by filtering or by determining a mean or average of different values of the first or second acceleration or position respectively. This also may allow for a more precise determination, in particular reduce dynamic effects, signal disturbances and the like.

According to one aspect it has been found that a difference between positive or negative accelerations of the car due to different positions of the clutch is essentially proportional to a factor resulting in particular from inertia and/or friction. Accordingly, th torque capacity value may be determined on the basis of a product of the difference between the first and second acceleration and a predetermined factor.

As inertia and friction acting upon a drive train depends on a transmissicn ratio of the coupled transmission, said factor is determined on the basis of an engaged gear or transmission ratio of a transmission coupled to the clutch according to one embodim'ent.

A formula to determine the torque capacity value on the basis of the difference between the first and second acceleration, in particular the factor, preferably Nith respect to the engaged gear, may be established on the basis of a model, in particularby simulation, and/or empirically by testing. For example the formula may be derived by determining the differences between accelerations determined with different positions of a clutch with known torque capacity and these differences then matched with the known torque capacity values at these positions.

According to one embodiment the computer program or a method implemented by the computer program respectively is carried out, i.e. one or more sequences of steps (a) to (c) are performed, wherein one, preferably forward, gear of the transmission which is coupled to one side of the clutch is engaged and/or wherein the power unit which is coupled to the other side of the clutch is running or non-running.

As explained before, in an intermediate position the slipping clutch transmits the maximum torque so that its torque capacity at this position can be determined. As also already explained above, if a gear of the transmission is engaged when the clutch is adjusted, the inertia and/or friction induced torque of the power unit and the drive train between power unit and clutch will act on the acceleration of the car, in particular due to the clutch gradually coupling said friction and/or inertia torque to driven wheels of the car.

According to one aspect of the present invention a system for determining a torque capacity of a clutch of a passenger car with respect to a position of the clutch comprise: means for determining a first acceleration of the car wherein the clutch is in a first position; means for determining a second acceleration of the car wherein the clutch is in a second position different from the first position; and means for determining a torque capacity value with respect to a difference between the first and second position on the basis of a difference between the first and second acceleration.

Said means according to the present invention may be realized by software, in particular a computer program computer program module, and/or by hardware, in particular by a processing unit, preferably comprising a microprocessor unit (CPU) andlor connected to a storage device and/or bus system, one or more sensors and/or actuators connected to or communicating with such processing unit respectively and/or a data carrier comprising program code for carrying out the computer program. The processing unit may be adapted to carry out instructions implemented in a storage device, receive input signals by a data bus system and/or transmit output signals to a data bus system. A storage device may comprise one or more, in particular different, storage media, in particular optical, magnetic, solid-state and/or other, preferably non-volatile, media.

The System may also be understood as comprising means in terms of function module architecture that is to be realized or implemented by the computer program or computer program module.

Said means in particular may be an apparatus, and in particular in terms of hardware a controller and/or a driver assistance device.

In particular, according to one aspect of the present invention an apparatus for determining a torque capacity of a clutch of a passenger car with respect to a position of the clutch comprises means for performing the following steps: (a) determining a first acceleration of the car wherein the clutch is in a first position; (b) determining a second acceleration of the car wherein the clutch is in a second position different from the first position; and (c) determining a torque capacity value with respect to a difference between the first and second position on the basis of a difference between the first and second acceleration.

Said means may be adapted to reiterate steps (a) to (c) for at least one further pair of a first and second position of the clutch determining a further torque capacity value.

Additionally or alternatively the first or second acceleration and position of a preceding sequence of steps (a) to (c) may establish a first or second acceleration and position in a successive sequence of steps (a) to (c).

Additionally or alternatively the clutch may be fully engaged or disengaged in a first or second position.

Additionally or alternatively the first and/or second position of at least one sequence of steps (a) to (c) may be a position between a position in which the clutch is fully engaged and a position in which the clutch is fully disengaged.

Additionally or alternatively the clutch may be more engaged or more disengaged in the first position then in the second position of at least one sequence of steps (a) to (c).

Additionally or alternatively said apparatus may comprise means for automatically adjusting the electrically operated clutch into the first and/or second position of at least one sequence of steps (a) to (c).

Additionally or alternatively said apparatus may comprise means for storing at least one determined torque capacity value.

Additionally or alternatively said apparatus may comprise means for maintaining the clutch in the first and/or second position of at least one sequence of steps (a) to (c) for a predetermined time.

Additionally or alternatively said apparatus may comprise means for smoothening the first and/or second determined acceleration and/or position of at least one sequence of steps (a) to (c).

Additionally or alternatively said means for determining a torque capacity value may be adapted to determine said torque capacity value on the basis of a product of a difference between the first and second acceleration and a predetermined factor.

Said means in particular may be adapted to determine the factor on the basis of an engaged gear of a transmission coupled to the clutch.

Additionally or alternatively one gear of a transmission which is coupled to one side of the clutch may be engaged. Additionally or alternatively a power unit which is coupled to the other side of the clutch may be running or non-running.

Said means also may be a data storage device, in particular a data carrier, on which a computer program as described herein is stored, in particular non-volatile.

According to one aspect of the present invention a passenger car comprises a power unit, a transmission, a clutch coupled between said power unit and transmission, and said system, in particular an apparatus, in particular a controller and/or a driver assistance device, for executing a computer program as described herein.

Further features of the present invention are disclosed in the sub-claims and the following description of preferred embodiments. Thereto it is shown, partially schematically, in: Fig. 1 an acceleration a of the car of fig. 3 and a position x of a clutch of said car with respect to time t; Fig. 2 a computer program or a method implemented by a computer program for determining a torque capacity of the clutch according to a preferred embodiment of the present invention; Fig. 3 a passenger car according to a preferred embodiment of the present invention; and Fig. 4 a torque capacity 1(x) with respect to a position x of a clutch.

Fig. 3 shows a passenger car according to a preferred embodiment of the present invention compiising a power unit in the form of an internal combustion engine 3, a manual transmission 2, an electrically operated clutch I coupled between said internal combustion engine 3 and said manual transmission 2, and means in the form of a ECU 5 communicating with an electrically operated actuator 6 for adjusting and determining a position of the clutch I and a sensor? for determining a longitudinal acceleration of the car.

ECU 5 executes a computer program or a method implemented by the computer program according to a preferred embodiment of the present invention which will be described with respect in particular to fig. 2 in further detail now.

In a step SI 0 the ECU 5 determines a first acceleration a1 of the car based on an input of sensor 7 wherein the clutch 1 is in a first position xi determined by actuator 6.

In a step S20 the ECU 5 determines an initial second position X2 based on an actual position x of the clutch determined by actuator 6.

In a step S30 it is determined whether an actual position x of clutch 1 determined by actuator 6 deviates from said initial second position X2, i.e. whether an actual position x of clutch 1 has changed.

If the actual position x deviates from the initial second position X2, preferably for at least a predetermined difference, (530: "Y") ECU 5 proceeds with step 530. Otherwise (530: "N") the computer program returns to step 520.

In step S40 the actual position x which is different from the initial second position X2 is determined as a new or actual second position X2. In a subsequent step 550 ECU 5 determines a second acceleration a2 of the car based on an actual input of sensor 7 wherein the clutch 1 is in the actual second position x2.

In a subsequent step 560 ECU 5 determines a torque capacity value T with respect to a difference between the first and the actual second position on the basis of a difference J a2 -au between the first and second acceleration a1, a2 by multiplying said difference I a2 -au by a factor M(i) which is determined depending on an engaged gear i of transmission 2. Said factor M(i) may be derived from a mode! or empirically. ECU stores said determined value in a look-up table corresponding to the second position x2 (T(x2) = T(x2-xi)).

The computer program returns to step 530, reiterating steps S40 to 560 upon deviation of the actual position x from actual second position X2.

In an exemplary embodiment said computer program or a method implemented by said computer program respectively is performed when a sailing mode -in which clutch I is in a fully disengaged position Xo% (see fig. 4) with a gear of transmission 2 coupled to one side of clutch 1 being engaged and internal combustion engine 3 coupled to the other side of clutch 1 non-running -is terminated by ECU 5 automatically adjusting the clutch position by actuator 6 to a fully engaged position Xloo% (see fig. 4), thereby cranking the non-running internal combustion engine 3.

Thus initially clutch 1 is fully disengaged in its position Xa = xQ% as can be seen in fig. 1 during sailing, i.e. up to time ta. In sailing mode the car is slightly decelerated due to aerodynamic resistance, gravitation, friction and dynamic forces and the like.

Therefore the fully disengaged position xa signaled by actuator 6 to ECU 5 is determined therein as a first position x1 anc an initial second position x2 and the negative longitudinal acceleration aa of the car signaled by sensor 7 to ECU 5 is determined therein as a first acceleration a1. Said first acceleration a1 yields a reference or offset due to aerodynamic resistance, gravitation, friction and dynamic forces and the like.

At time ta actuator 6 adjusts clutch 1 into a more engaged position xc which is a position between a position in which clutch us fully engaged and a position in which clutch I is fully disengaged. Clutch 1 transmits torque from internal combustion engine 3 and the drive train between engine 3 and clutch 1. Therefore the car decelerates more, i.e. its (negative) acceleration increases to a, as it is indicated by the dash-dotted line in fig. 1.

Due to the change of the actual clutch position step S30 is answered in the affirmative so that ECU 5 now determines position xc as a (new) second position x2 in step 840 and acceleration ab as a second acceleration a2 in step 850 and determines a corresponding further torque capacity value T(x2-xi) = 1(x2) in step 860 before returning to step S30.

At time tb actuator 6 adjusts clutch I into a further engaged position xc which still is a position between a position in which clutch I is fully engaged and a position in which clutch 1 is fully disengaged. Clutch 1 therefore now transmits yet more torque from internal combustion engine 3 and the drive train between engine 3 and clutch 1. Therefore the car decelerates more, i.e. its acceleration raises to a.

Accordingly, ECU 5 in a second sequence of steps 830 to 860 now determines position xc as a new second position X2 in step 840 and acceleration a as a new second acceleration a2 in step 850 and determines a further torque capacity value T(x2-xi) = T(x2) in step S60 before returning to step 830.

At time t actuator 6 adjusts clutch 1 into a fully engaged position xc = Xjoo%.

Clutch 1 therefore transmits even more torque from internal combustion engine 3 and the drive train between engine 3 and clutch 1. Therefore the car decelerates more, i.e. its acceleration finally is enlarged to ad (see dash-dotted line in fig. 1). Accordingly ECU 5 reiterates sequence of steps S30 to S60 one more time.

In this way, three torque capacity values T(xb), T(x) and T(xd = XIoo%) are determined and stored from which a torque capacity with respect to the position of clutch 1 can be determined as it is shown in fig. 4.

One should note that a (negative) acceleration aa of the car in sailing mode, i.e. until terminating sailing mode by beginning to engage clutch I at ta, due to aerodynamic resistance, gravitation, friction and dynamic forces is sort of eliminated by referring to the fully disengaged position as the first position x1. One should also note that the determined torque capacity values T(x2-xi) = 1(x2) indicate absolute torque capacities with respect to T(xi = xo%) = C defining a reference. Therefore, a curve as depicted in fig. 4 mirrored along the T(x) axis will result, where more negative values of x indicate a more engaged or closed clutch.

The ECU5 may include a digital central processing unit (CPU) or processor in communication with a memory system and an interface bus. Instead of an ECU, the system may have a different type of processor to provide the electronic logic, e.g. an embedded controller, an onboard computer, or any processing module that might be deployed in the vehicle. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to and from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to and from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to execute the steps of such control methods.

The program stored in the memory system is transmitted from outside via a cable or in a wireless fashion. Outside the system it is normally visible as a computer program product, which is also called transient or non-transient computer readable medium or machine readable medium in the art, and which should be understood to be a computer program code residing on a carrier, the carrier preferably being either transitory or non-transitory in nature with the consequence that the computer program product can be regarded to be transitory or non-transitory in nature.

An example of a transitory computer program product is a signal, e.g. an electromagnetic signal such as an optical signal, which is a transitory carrier for the computer program code. Carrying such computer program code can be achieved by modulating the signal by a conventional modulation technique such as QPSK for digital data, such that binary data representing sad computer program code is impressed on the transitory electromagnetic signal. Such signals are e.g. made use of when transmitting computer program code in a wireless fashion via a WiFi connection to a laptop.

In case of a non-transitory computer program product the computer program code is embodied in a tangible storage medium. The storage medium is then the non-transitory carrier mentioned above, such that the computer program code is permanently or non-permanently stored in a reirievable way in or on this storage medium.

The storage medium can be of conventional type known in computer technology such as a flash memory, an Asic, a CD or the like.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

I clutch 2 transmission 3 internal combustion engine (power unit) 4 driven wheel

ECU

6 actuator 7 sensor a acceleration T torque x position

Claims

Claims 1. A method for determining a torque capacity (T(x)) of a clutch (1) of a passenger car with respect to a position (x) of the clutch (1), comprising the steps: (a) determining (Si 0) a first acceleration (ai) of the car wherein the clutch (1) is in a first position (xi); (b) determining (S50) a second acceleration (a2) of the car wherein the clutch (1) is in a second position (x2) different from the first position (xi); and (c) determining (860) a torque capacity value (T(x2-xl)) with respect to a difference (x2-xi) between the first and second position (x1, x2) on the basis of a difference (1a2-aiI) between the first and second acceleration (ai a2).
2. A method according to the preceding claim, wherein steps (a) to (c) are reiterated for at least one further pair of a first and second position (xi, x2) of the clutch (1) determining a further torque capacity value (T(x2-xi)).
3. A method according to the preceding claim, wherein the first or second acceleration (a1, a2) and position (x1, x2) of a preceding sequence of steps (a) to (c) establishes a first or second acceleration (ai, a2) and position (xi, x2) in a successive sequence of steps (a) to (c).
4. A method according to one of the preceding claims, wherein the clutch (1) is fully engaged or disengaged in a first or second position (xi, x2).
5. A method according to one of the preceding claims, wherein the first and/or second position (xi, x2) of at least one sequence of steps (a) to (c) is a position between a position (xioo%) in which the clutch (1) is fully engaged and a position (xo%) in which the clutch (1) is fully disengaged.
6. A method according to one of the preceding claims, wherein the clutch (1) is more engaged or more disengaged in the first position (xi) then in the second position (x2) of at least one sequence of steps (a to (c).
7. A method according to one of the preceding claims, wherein the electrically operated clutch (1) is automatically adjusted into the first and/or second position (xi, x2) of at least one sequence of steps (a) to (c).
8. A method according to one of the preceding claims, wherein at least one determined torque capacity value (T(xrXi)) is stored.
9. A method according to one of the preceding claims, wherein the clutch (1) is maintained in the first and/or second position (T(xrxi)) of at least one sequence of steps (a) to (c) for a predetermined time (tb-ta).
10. A method according to one of the preceding claims, wherein the first and/or second determined acceleration (ai, a2) and/or position (Xli x2)of at least one sequence of steps (a) to (c) is smoothened.
11. A method according to one of the preceding claims, wherein a torque capacity value (T(x2-xi)) is determined on the basis of a product of a difference between the first and second acceleration (larail) and a predetermined factor(M(i)).
12. A method according to the preceding claim, wherein the factor (M(i)) is determined on the basis of an engaged gear (i) of a transmission (2) coupled to the clutch (1).
13. A method according to one of the preceding claims, wherein one gear of a transmission (2) which is coupled to one side of the clutch (1) is engaged and/or wherein a power unit (3) which is coupled to the other side of the clutch (1) is running or non-running.
14. A system (5-7) for determining a torque capacity (T(x)) of a clutch (1) of a passenger car with respect to a position (X) of the clutch (1), comprising: means (5, 7)for determining a first acceleration (ai) of the car wherein the clutch (1) is in a first position (xi); means (5, 7) for determining a second acceleration (a2) of the car wherein the clutch (1) is in a second position (x2) different from the first position (xi); and means (5, 6) for determining a torque capacity value (T(xrxi)) with respect to a difference (x2-x1) between the first and second position (xi, x2) on the basis of a difference (1a2-alI) between the first and second acceleration (a1, a2).
15. A passenger car comprising a power unit (3), a transmission (2), a clutch (1) coupled between said power unit (3) and transmission (2), and a system (5-7) according to the preceding claim.