SE541567C2

SE541567C2 - Method and system for controlling torque transmitting means of a vehicle

Info

Publication number: SE541567C2
Application number: SE1750353A
Authority: SE
Inventors: Erik Gustafsson; Fredrik Jarngren; Georg Åhrberg
Original assignee: Scania Cv Ab
Priority date: 2017-03-24
Filing date: 2017-03-24
Publication date: 2019-11-05
Also published as: DE102018001780A1; SE1750353A1

Abstract

The present invention relates to a method for a vehicle (100),the vehicle (100) including:torque transmitting means (106) for selectively transmitting torque between a power source (101) and a gearbox (103) of the vehicle (100), anddriver manoeuvrable means (118), wherein transmittable torque of the torque transmitting means (106) is controllable in dependence of an electrical signal representing a position of the driver manoeuvrable means (118),the method including, when the vehicle is in motion:- detecting if engagement of the torque transmitting means (106) is initiated by means of the driver manoeuvrable means (118), and- if detecting said initiation of engagement of the torque transmitting means (106), influencing a speed of rotation of the power source (101) towards a speed of rotation of an input shaft (109) of the gearbox (103).

Description

METHOD AND SYSTEM FOR CONTROLLING TORQUE TRANSMITTING MEANS OF A VEHICLE Field of the invention The present invention relates to vehicles, and in particular to a method and system for controlling torque transmitting means of a vehicle. The present invention also relates to a vehicle, as well as a computer program and a computer-readable medium that implement the method according to the invention.

Background of the invention There exist various kinds of vehicle transmissions. For example, vehicle transmissions can be of a fully automatic kind, where a vehicle control system controls gear changing operations. The gearboxes being used in these systems may consist of automated manual transmissions where the vehicle control system automatically controls gear shifting in “manual” gearboxes.

There also exist manual transmissions where the vehicle driver is in control of the gear changing operation. A change of gear in manual transmissions is often performed through the use of a driver controllable clutch, oftentimes through the use of a clutch pedal. Clutches can also be used in automated manual transmissions, in which case clutch operation when changing gear is controlled by the vehicle control system and not by the driver. There also exist systems having automated manual transmissions, where driver controllable means such as a clutch pedal is present and which may be used when starting the vehicle from standstill. When the vehicle has been set in motion, subsequent changes of gear can be arranged to be controlled completely by the vehicle control system without driver interaction and without further manoeuvring of the clutch, i.e. changes of gear being performed with the drivetrain closed. Hence, in this case, the clutch is completely controlled by the driver using a clutch pedal being directly (mechanically) linked to the clutch actuator.

The present specification relates to systems where the driver manoeuvrable means such as a clutch pedal or other means is used to control torque transmitting means such as a clutch or other torque transmitting means, but not directly through the use of a mechanical linkage. Instead, e.g. the torque transmitting means is controlled through the use of clutch-by-wire (CBW) systems. In clutch-by-wire systems an electrical signal representing e.g. a clutch pedal position is translated into a corresponding request for torque transmission, such as a corresponding clutch movement. For example, a position sensor or other suitable means can be used to detect a position of the driver manoeuvrable means, such as e.g. the position of a clutch pedal. An electrical signal representing this position is then translated into a corresponding driver request regarding e.g. clutch operation, and the vehicle control system controls e.g. the actual clutch movement in dependence of the signal representing the position of the clutch pedal. The actual clutch movement, consequently, is not mechanically linked to movements of the driver manoeuvrable means.

Systems of this kind may provide advantages in the operation of the vehicle.

Summary of the invention It would be advantageous to achieve a method and system that increases driver comfortability in situations when the driver engages torque transmission between a power source and a gearbox through control of torque transmission means using driver manoeuvrable means. To better address this concern a method and system having the features defined in the independent claims are provided.

According to the present invention, it is provided a method for a vehicle, the vehicle including: torque transmitting means for selectively transmitting torque between a power source and a gearbox of the vehicle, and driver manoeuvrable means, wherein transmittable torque of the torque transmitting means is controllable in dependence of an electrical signal representing a position of the driver manoeuvrable means, the method including, when the vehicle is in motion: - detecting if engagement of the torque transmitting means is initiated by means of the driver manoeuvrable means, and - if detecting said initiation of engagement of the torque transmitting means, influencing a speed of rotation of the power source towards a speed of rotation of an input shaft of the gearbox.

There exist various kinds of transmission systems, where a change of gear may be performed manually or automatically. The transmission systems, irrespective whether of a manual gearshift or automatic gearshift kind, may include a clutch or other torque transmission means that can be used to selectively disengage, i.e. interrupt, torque transmission through the drivetrain. Such systems may further comprise driver manoeuvrable means for allowing driver manoeuvring of the torque transmitting means. For example, a further pedal in addition to e.g. an accelerator and a brake pedal may be utilised. Such driver manoeuvrable means for controlling torque transmitting means may also be present in hybrid vehicles.

The torque transmitting means may be controlled by the driver manoeuvrable means where a signal, such as an electrical signal, may be used to represent a position of the driver manoeuvrable means, such as e.g. a clutch pedal position, where the vehicle control system then controls the torque transmitting means on the basis of the position signals.

Torque transmitting means may be engaged from a disengaged state. When the transmission of torque is disengaged, there is an interruption in the transmission of torque between power source and gearbox, where transmission of torque may be commenced by engaging the torque transmitting means. If the vehicle is in motion when the torque transmitting means are disengaged and the transmission of torque is interrupted, i.e. there is no ongoing transmission of torque, the power source may be rotating at one speed of rotation while an input shaft of the gearbox may be rotating at another speed of rotation determined by, inter alia, vehicle speed, wheel diameter and the total gear ratio between gearbox input shaft and vehicle drive wheels. If the vehicle speed is changing, e.g. due to road inclination, the gearbox input shaft speed may in addition be constantly changing.

When engaging torque transmission between power source and gearbox in situations where the vehicle is in motion, discomforting jerks and/or drivetrain oscillations may occur if the speed of rotation of the power source is not synchronised with the speed of rotation of the gearbox input shaft when engaging the torque transmitting means.

For this reason, the driver oftentimes attempts to synchronise the speed of rotation of the power source with the speed of rotation of the gearbox input shaft. This, however, may be difficult to accomplish.

According to the present invention, discomforts due to differences in speed of rotation of the power source and speed of rotation of the gearbox input shaft may be reduced.

According to the invention, this is accomplished by a method where it is detected if engagement of the torque transmitting means is initiated by means of the driver manoeuvrable means. For example, this detection may be accomplished by the vehicle control system monitoring the electrical signal representing the position of the driver manoeuvrable means, wherein changes in the electrical signal may be translated into a corresponding movement (i.e. change in position) of the driver manoeuvrable means. The detection may be performed by the vehicle control system, or in any other suitable way.

If initiation of engagement of the torque transmitting means is detected, a speed of rotation of the power source is influenced towards the speed of rotation of the input shaft with the gearbox. For example, if such initiation of engagement is detected, the speed of rotation of the power source may be influenced so as to be more in synchronism with the speed of rotation of the gearbox input shaft upon engagement of the torque transmitting means.

In this way, jerks and/or drivetrain oscillations that otherwise may occur due to differences in speed of rotation between the power source and the input shaft of the gearbox may be reduced by controlling the vehicle power source such that its speed of rotation better coincides with the speed of rotation of the gearbox input shaft than would have been the case if the control of the speed of rotation of the power source had been left completely to the driver. Consequently, a more comfortable engagement of the torque transmitting means may be obtained.

The initiation of the engagement of the torque transmitting means may be detected, for example, if it is detected a movement of the driver manoeuvrable means from a position representing a complete interruption of the transmission of torque towards a position representing a request for a full transmissibility of torque. The driver manoeuvrable means may for example be manoeuvrable by the driver in a movement region between a first end position, representing a request for a full transmissibility of torque, and a second end position, representing a complete interruption of the transmission of torque. Hence, initiation of engagement of the torque transmitting means may be detected when it is detected a change in position of the driver manoeuvrable means from the position representing a complete interruption in the transmission of torque of the torque transmitting means. The driver manoeuvrable means may be a clutch pedal and the torque transmitting means may be a clutch.

Furthermore, according to embodiments of invention, when influencing the speed of rotation of the power source, the speed of rotation of the input shaft of the gearbox may repeatedly (e.g. continuously) be determined so that the speed of rotation the power source may repeatedly (e.g. continuously) be controlled towards the speed of rotation of the input shaft of the gearbox to thereby account for changes in speed of rotation of the gearbox.

According to embodiments of the invention the speed of rotation of the power source is increased if the speed of rotation of the input shaft increases, and/or the speed of rotation of the power source is decreased if the speed of rotation of said input shaft decreases.

Further, it is estimated an expected speed of rotation of the input shaft of said gearbox at a time of engagement of the torque transmitting means, and the speed of rotation of said power source is influenced based on said estimation. The expected speed of rotation of the gearbox input shaft may be an expected speed of rotation at the time when the transmittable torque of torque transmitting means commences. As soon as transmission of torque commences this will commence a forced synchronization, which will be completed as soon as the transmittable torque of the torque transmitting means equals or exceeds the torque that at the time is being transmitted by the drivetrain.

The estimated expected speed of rotation may also be the speed of rotation of the gearbox input shaft when the torque transmitting means reaches a first (e.g. predetermined) transmittable torque, such as torque that will prevail in the drivetrain upon engagement, since when this transmittable torque is reached the speed of rotation of the power source will equal the speed of rotation of the gearbox input shaft.

In addition to controlling the speed of rotation of the power source, the engagement of the torque transmitting means may also be influenced in a manner where the torque transmitting means are controlled such that an actual transmittable torque deviates from the transmittable torque as requested by the driver manoeuvrable means. For example, the engagement of the torque transmitting means may be delayed by the vehicle control system to allow synchronization of the speed of rotation of the power source.

According to embodiments of the invention, it is estimated if the torque transmitting means, when controlled according to the driver manoeuvrable means, will engage prior to the speed of rotation of the power source reaches the speed of rotation of said input shaft, and in this case engagement of said torque transmitting means may be delayed.

For example, according to embodiments of the invention, engagement of the torque transmitting means may be delayed until the speed of rotation of said power source deviates at most by a first (e.g. predetermined) difference in speed of rotation in relation to the speed of rotation of the input shaft of the gearbox. According to embodiments of the invention, engagement of the torque transmitting means is delayed at most by first (e.g. predetermined) period of time in relation to time of engagement if controlled according to the driver manoeuvrable means. In this way, a delay may be imposed that does not differ too much from the expected engagement by the driver.

When engaging torque transmitting means when the vehicle is in motion, the driver often times attempts to synchronize the speed of rotation of the power source the speed of rotation of the gearbox input shaft. As stated above, such synchronization may not always be accomplished to satisfying extent. According to embodiments of the invention, it is determined a driver requested speed of rotation of the power source, i.e. the speed of rotation to which the power source is controlled by the driver, and when influencing the speed of rotation of the power source, speed of rotation of the power source can be controlled such that it deviates at most a predetermined number of revolutions per minute (rpm) from the driver requested speed of rotation. In this way, the difference in speed of rotation between the actual speed of rotation of the power source and the speed of rotation as expected by the driver can be controlled to obtain a vehicle behaviour that does not deviate to an extent that may confuse the driver.

Furthermore, vehicles often times display a speed of rotation of the power source to the driver, and, according to embodiments of the invention, a speed of rotation of the power source may be displayed to the driver that more corresponds to the speed of rotation requested by the driver than does the actual speed of rotation of the power source. That is, it is displayed a speed of rotation of the power source that deviates from the actual speed of rotation of the power source in a manner such that the displayed speed of rotation is closer to the speed of rotation as requested the driver than the actual speed of rotation. In this way impacts of the invention on the driver expected vehicle behaviour may be reduced.

According to embodiments of the invention, the speed of rotation of the power source is only influenced if it is determined that a driver of the vehicle controls the speed of rotation of the power source towards the speed of rotation of the input shaft. That is, the speed of rotation of the power source is only influenced if it is determined that the driver already attempts to synchronize the speed of rotation of the power source.

According to embodiments of the invention speed of rotation of the power source is only influenced if the driver requested speed of rotation of the power source is an idling speed. In this case, the invention may be utilized to avoid jerks/oscillations when the torque transmitting means are engaged.

When influencing the speed of rotation of the power source according to the invention, it may be ensured that it is only the speed of rotation that is influenced and not the transmission of torque from the power source. Hence it may be ensured that the power source does not deliver any, or at least not noticeably, more torque than expected by the driver.

The speed of rotation of the power source may also be arranged to only be influenced if a gear for propulsion of the vehicle is engaged in said gear box, at least one vehicle drive wheel thereby being in torque transmitting connection with the gearbox input shaft.

According to embodiments of the invention, the driver manoeuvrable means comprises a pedal to be manoeuvred by a foot of the driver, for example a clutch pedal.

The torque transmitting means may comprise a clutch such as a friction clutch. The clutch may further comprise a first clutch portion arranged for rotation with an output shaft of the power source, and a second clutch portion arranged rotation with the input shaft of the gearbox. By controlling the speed of rotation of the power source, the speed of rotation of the first clutch portion may be controlled towards the speed of rotation of the second clutch portion so that ideally the speeds of rotation are synchronized, or at least the portions are rotating with a reduced difference in speed of rotation, to allow smooth engagement of the clutch by bringing the two clutch portions together, thereby reducing uncomfortable jerk/drivetrain oscillations.

As stated, the torque transmitting means may comprise a clutch. However, the torque transmitting means for controlling transmission of torque to/from a power source may also be of other designs. For example, a conventional clutch may be replaced by torque transmitting means comprising one or more electrical machines and suitable gearing, where such other kind of torque transmitting means still may be arranged e.g. between a power source such as an internal combustion engine and a gearbox, e.g. a gearbox comprising distinct gears. With regard to such other torque transmitting means, the gearing may e.g. comprise one or more planetary gears, or other suitable gearing, where the electrical machine(s) and power source such as an internal combustion engine may be arranged in a torque balanced relationship such that when no torque is applied by the electrical machine, this limits the torque that can be transmitted by the power source to the gearbox to essentially zero, and where a higher applied torque by the electrical machine allows a higher transmission of torque from the power source, where the torque that can be applied by the power source may be the torque applied by the electrical machine times a factor. In this embodiment, the vehicle may comprise a power source in the form of an internal combustion engine, while functionality resembling a slipping clutch may be obtained by controlling transmission of torque by the electrical machine.

Driver manoeuvrable means such as a pedal may then be used, where a first end position, such as a released pedal, may represent a request for a high, maximally transmittable torque, similar to a closed clutch, and a second end position, such as depressed pedal, may represent an interrupted transmission, e.g. zero torque, by controlling the electrical machine to deliver e.g. zero torque. The electrical machine may be controlled to provide varying transmittable torque to/from the power source in dependence of the position of the driver manoeuvrable means. The driver may in addition control speed of rotation of the power source through the use of simultaneous operation of an accelerator. Solutions of this kind allows different speeds of rotation of the power source and gearbox input shaft, where the speeds of rotation will be brought into synchronism as higher torque is applied. Solutions of this kind may e.g. be used when embodiments of the invention is implemented in hybrid vehicles, such as electric hybrid vehicles.

Further, as is appreciated by the person skilled in the art, torque transmitting means such as clutches and other means may be of various designs, and the particular design, e.g. whether the clutch is a friction clutch or not, is not of relevance to the present invention. The present invention may be applicable in any system providing clutch-by-wire functionality, irrespective of whether an actual clutch is present.

It will be appreciated that the embodiments described in relation to the method aspect of the present invention are all applicable also for the vehicle system aspect of the present invention. That is, the vehicle system may be configured to perform the method as defined in any of the above described embodiments. Further, the method may be a computer implemented method.

Further characteristics of the present invention and advantages thereof are indicated in the detailed description of exemplary embodiments set out below and the attached drawings.

Brief description of the drawings Fig. 1A illustrates a powertrain of an exemplary vehicle; Fig. 1B illustrates an example of a control unit in a vehicle control system; Fig. 1C illustrates a clutch pedal of the exemplary vehicle of Fig. 1A.

Fig. 2 illustrates an exemplary method according to embodiments of the invention.

Fig. 3 illustrates an exemplary clutch pedal characteristic of a vehicle in which the present invention may advantageously be utilised.

Detailed description of exemplary embodiments As was mentioned above, embodiments of the invention are applicable not only to systems comprising a clutch but to any kind of system where controllable torque transmitting means are used to control transmission of torque to and/or from a power source using driver manoeuvrable means. As was further mentioned above, such systems may e.g. include systems where an electrical machine and gearing are used to replace functionality of a conventional clutch, e.g. in electric hybrid vehicles.

Flowever, in the following detailed description, for reasons of simplicity, embodiments of the invention are exemplified for a system where a clutch is controlled by driver manoeuvrable means. Furthermore, the driver controllable means for controlling a clutch is exemplified by a clutch pedal in the following detailed description. The present invention is, however, applicable for any kind of driver controllable means for controlling a clutch, where the driver controllable means is movable in a movement region.

Fig. 1A schematically depicts a powertrain of an exemplary vehicle 100. The powertrain comprises a power source, in the present example a combustion engine 101, which, in a conventional manner, is connected via an output shaft of the combustion engine 101, normally via a flywheel 102, to a gearbox 103 via a clutch 106. An output shaft 107 from the gearbox 103 propels drive wheels 113, 114 via a final drive 108, such as a common differential, and drive axles 104, 105 connected to said final drive 108.

The combustion engine 101 is controlled by a vehicle control system via a control unit 117. The clutch 106 and gearbox 103 are also controlled by the vehicle control system by means of a control unit 116. According to the present example, the clutch comprises a dry clutch where a friction element (disc) 110 is connected to, and rotates with, a first gearbox element, e.g. an input shaft 109 of the gearbox 103. The friction element 110 selectively engages the flywheel 102, or any other suitable rotating part of the combustion engine 101, to transmit torque to/from the combustion engine 101, i.e. between combustion engine 101 and powertrain components downstream of the clutch 106, such as to/from at least one of the drive wheels 113, 114 via the gearbox 103.

The engagement of the friction element 110 with the engine flywheel 102 is controlled by means of a pressure plate 111 by means of a lever arm 112, which is manoeuvred by a clutch actuator 115.

In fully mechanical systems where the clutch is controlled directly by means of a clutch pedal, the clutch pedal is mechanically linked to the clutch. For example, the clutch pedal can be mechanically linked to the lever arm in order to directly control movement of the friction element. That is, a movement of the clutch pedal is mechanically linked to the clutch, and a movable clutch element, such as friction element moves in synchronism with the clutch pedal. It is to be understood that the exemplified clutch is merely an example, and that clutches, irrespective of whether the clutch constitutes part of a clutch-by-wire system or is controlled mechanically by driver controllable means, may be of various designs. For example, the clutch actuator may be arranged coaxially with the gearbox input shaft.

According to clutch-by-wire systems, such as the presently exemplified system, opening and closing of the clutch 106 may be controlled by the driver using driver manoeuvrable means such as a clutch pedal 118. In this case, however, the clutch pedal does not directly control the influence of the clutch actuator 115 on the lever arm 112 by a mechanical link. Instead, the clutch is controlled by the vehicle control system in dependence of one or more signals representing the clutch pedal 118 position.

Since the actual movement of the lever arm 112 is not mechanically linked to the clutch pedal 118 this means, in turn, that the clutch pedal 118 position, instead, is used as a request for a particular transmittable torque, e.g. represented by clutch friction element/actuator position, which is then, by means of the vehicle control system, translated into an actual clutch movement via the clutch actuator 115. Hence actual manoeuvring of the clutch, i.e. the positioning of the lever arm 112 in the present example, is performed by the vehicle control system when the clutch is driver controlled, where this manoeuvring is dependent on the clutch pedal 118 position.

However, since the actual manoeuvring is under the control of the vehicle control system, this allows that the clutch may also be controlled by the vehicle control system completely independent from the clutch pedal. The clutch may hence be controlled according to different modes, where actual clutch movement is always performed by the vehicle control system, but where the movement in a driver controlled mode is performed on the basis of signals representing the position of the clutch pedal, and in an automatic mode clutch movement is performed independently from the current position of the clutch pedal.

An exemplary clutch pedal 118 is schematically shown in Fig. 1C. The clutch pedal 118 is movable within a movement region defined by two end positions A, B, defining an angular range a. The clutch pedal 118 position in said movement region may be determined, e.g. by means of a suitable sensor, such as a potentiometer or an angle sensor 119 or any other suitable kind of sensor which determines the current position of the clutch pedal 118 in the movement region in which the clutch pedal is movable. When the clutch pedal 118 is fully released, i.e. not manoeuvred by the driver, it is in a state of rest in position A, e.g. by means of a spring force, where position A represents a fully closed clutch. Position B represents a fully depressed clutch pedal and hence a fully open clutch. Fig. 1A also discloses an accelerator pedal 130 by means of which the driver requests power from the internal combustion engine 101.

As was mentioned above, the clutch may be controlled in dependence of the clutch pedal (driver manoeuvrable means). However, an advantage of clutch-by-wire systems is that the clutch may also be controlled by the vehicle control system independently from the clutch pedal. This is also often times utilized, e.g. to allow the vehicle to be driven as a two pedal (accelerator, brake pedal) vehicle if so desired, where the clutch pedal may be used to provide additional control as was described above. According to embodiments of the invention, it is provided a method and system that may increase driver comfortability and that may reduce wear on components. An exemplary method 200 of the present invention is shown in Fig. 2, which method may be implemented at least partly e.g. in the control unit 116 for controlling the clutch 106 and gearbox 103. As indicated above, the functions of a vehicle are, in general, controlled by a number of control units, and control systems in vehicles of the disclosed kind generally comprise a communication bus system consisting of one or more communication buses for connecting a number of electronic control units (ECUs), or controllers, to various components on board the vehicle. Such a control system may comprise a large number of control units, and the control of a specific function may be divided between two or more of them.

For the sake of simplicity, Fig. 1 A depicts only control units 116-117, but vehicles 100 of the illustrated kind are often provided with significantly more control units, as one skilled in the art will appreciate. Control units 116-117 are arranged to communicate with one another and various components via the communication bus system and other wiring, partly indicated by interconnecting lines in Fig. 1A.

Embodiments of the invention may be implemented in any suitable control unit in the vehicle 100, and hence not necessarily in the control unit 116. The control of the clutch 106 according to embodiments of the invention will usually depend on signals being received from other control units and/or vehicle components, and it is generally the case that control units of the disclosed type are adapted to receive sensor signals from various parts of the vehicle 100. The control unit 116 may, for example, receive signals from clutch pedal position sensor 119 and clutch actuator 115. Further, the control unit may receive signals representing driver request for power from the internal combustion engine, such as by means of the accelerator pedal 130. Control units of the illustrated type are also usually adapted to deliver control signals to various parts and components of the vehicle, e.g. to control the clutch actuator 115.

Control of this kind is often accomplished by programmed instructions. The programmed instructions typically comprises a computer program which, when executed in a computer or control unit, causes the computer/control unit to exercise the desired control, such as method steps according to the present invention. The computer program usually constitutes a part of a computer-readable medium, wherein said computer-readable medium comprises a suitable storage medium 121 (see Fig. IB) with the computer program 126 stored on said storage medium 121. The computer program may be stored in a non-volatile manner on said storage medium. The digital storage medium 121 may, for example, comprise any of the group comprising: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit etc., and be arranged in or in connection with the control unit, whereupon the computer program is executed by the control unit. The behaviour of the vehicle in a specific situation may thus be adapted by modifying the instructions of the computer program.

An exemplary control unit (the control unit 116) is shown schematically in Fig. 1B, wherein the control unit may comprise a processing unit 120, which may comprise, for example, any suitable type of processor or microcomputer, such as a circuit for digital signal processing (Digital Signal Processor, DSP) or a circuit with a predetermined specific function (Application Specific Integrated Circuit, ASIC). The processing unit 120 is connected to a memory unit 121, which provides the processing unit 120, with e.g. the stored program code 126 and/or the stored data that the processing unit 120 requires to be able to perform calculations. The processing unit 120 is also arranged so as to store partial or final results of calculations in the memory unit 121.

Furthermore, the control unit 112 is equipped with devices 122, 123, 124, 125 for receiving and transmitting input and output signals, respectively. These input and output signals may comprise waveforms, pulses or other attributes that the devices 122, 125 for receiving input signals may detect as information for processing by the processing unit 120. The devices 123, 124 for transmitting output signals are arranged so as to convert calculation results from the processing unit 120 into output signals for transfer to other parts of the vehicle control system and/or the component (s) for which the signals are intended. Each and every one of the connections to the devices for receiving and transmitting respective input and output signals may comprise one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Oriented Systems Transport) or any other bus configuration, or of a wireless connection.

Returning to the exemplary method 200 illustrated in Fig. 2, the method starts in step 201. As was mentioned above, embodiments of the invention relate to a method and system having an aim to reduce discomforting jerks/drivetrain oscillations when engaging torque transmitting means. In addition, wear of components may be reduced. The method according to the invention is carried out only if the vehicle is in motion, since in general it is only in this case that the input shaft 109 of the gearbox 103 is in rotation. Optionally, the method may comprise determining if the vehicle is in motion. According to embodiments of the invention, it may further be required that a gear for propulsion of the vehicle is engaged in the gearbox 103 so that the rotation of the drive wheels is translated into rotation of the gearbox input shaft 109 through the drivetrain. According to embodiments of the invention, the method may be arranged to be carried out for all vehicle speeds, but, the method may also be arranged to be carried out only for vehicle speeds resulting in a speed of rotation of the gearbox input shaft 109 that equals or exceeds an idling speed of rotation of the power source 101.

In step 201 it is determined whether the torque transmitting means, in this case clutch 106 is disengaged. According to embodiments of the invention, it is required that the clutch 106 is fully open, i.e. the transmission of torque is completely interrupted such as when friction plate 110 does not contact flywheel 102. The method remains in step 201 for as long as this is not the case, while the method continues to step 202 when the clutch 106 is disengaged.

In step 202, it is determined whether an engagement of the clutch 106 is initiated. If this is not the case, the method returns to step 201 while otherwise the method continues to step 203. Whether or not an engagement of the clutch is initiated may be detected, for example, by detecting a movement of the clutch pedal 118 from the position B (Fig. 1C) representing a complete interruption of the transmission of torque towards the position A representing a request for a full transmissibility of torque, i.e. closed drivetrain. The movement may further be detected by the vehicle control system monitoring an electrical signal representing the position of the clutch pedal 118. As was mentioned, it may be required that a clutch motion from a fully open position is detected, but it may also be sufficient the motion is detected from any position towards position A, for as long as the speed of rotation of the power source can be controlled substantially independently from the speed of rotation of the gearbox 103 input shaft 109, i.e. no or only limited torque is transmittable by the clutch, since when the clutch is capable of transmitting higher torques than currently is being transmitted by the drivetrain there will be no difference in speed of rotation between internal combustion engine and gearbox input shaft.

In step 203 it is determined whether the speed of rotation of the internal combustion engine 101 is to be influenced towards the speed of rotation of the gearbox 103 input shaft 109.

According to embodiments of the invention, the speed of rotation of the internal combustion engine may be arranged to always be influenced, while according to embodiments of the invention the speed of rotation of the internal combustion engine may be arranged to be influenced only when some criteria is fulfilled.

For example, the speed of rotation of the power source may be arranged to be influenced only if it is determined that the difference in speed of rotation between internal combustion engine and gearbox input shaft upon engagement will exceed some predetermined difference such as e.g. a predetermined number of revolutions per minute (rpm), where this difference may be set e.g. in dependence of the expected torque upon engagement of the clutch, see below, and hence the impact the difference in speed will have e.g. on comfortability.

The speed of rotation may also be arranged to be influenced only if the speed of rotation of the internal combustion engine deviates from the speed of rotation of the gearbox input shaft by more than some predetermined difference in speed of rotation. This may be determined, for example, by determining a current speed of rotation of the gearbox input shaft 109 and compare this speed of rotation with the speed of rotation of the internal combustion engine 101.

The speed of rotation of the internal combustion engine 101 may also be arranged to only be influenced if a gear for propulsion of the vehicle is engaged in the gearbox 103 so that the drive wheels 113, 114 are in torque transmitting connection with the gearbox input shaft 109, thereby causing the gearbox input shaft 109 to rotate.

An expected transmission of torque when closing the clutch may also be used as parameter when determining whether to influence the speed of rotation of the power source. The drivetrain torque at engagement of the clutch will primarily consist of dynamic torque generated by acceleration of the drivetra in/powertrain components, where the acceleration is caused when differing speeds of rotation of the flywheel and gearbox input shaft are brought into synchronisation as the torque transmitting means engages. It is also mainly this dynamic torque that may give rise to jerks and oscillations when the torque transmitting means engages. The dynamic torque may also be harmful.

Factors such as moment of inertia are in general well known for the components of the drivetrain, and also of the internal combustion engine. Furthermore, the speed of rotation of the gearbox input shaft 109 may be determined in a straightforward manner either directly by a rotation sensor or through knowledge of drive wheel diameter and gear ratios of gearbox (which may comprise a combination of a plurality of gears such as split gear, range gear and main gearbox, as is known per se) and final drive and possible further gear ratios from drive wheel to gearbox input shaft.

The speed of rotation of the gearbox 103 input shaft 109 may oftentimes already be available in the vehicle control system. Similarly, the speed of rotation of the internal combustion engine 101 is in general available in the vehicle control system. The expected acceleration of portions of the drive/powertrain may thereby be established in a straight forward manner, and also the dynamic torque and also overall torque that the drivetrain will be subjected to upon engagement may be determined, and if this torque exceeds some limit this may be used as reason for influencing the speed of rotation of the power source, since a reduced difference in speed of rotation between power source and gearbox input shaft will reduce the torque the drivetrain is subjected to upon engagement.

If it is determined in step 203 that the speed of rotation of the power source (internal combustion engine) is to be influenced, the method continues to step 204, otherwise the method is ended in step 206. In step 204 the speed of rotation of the internal combustion engine 101 is controlled towards the expected/estimated speed of rotation of the gearbox input shaft 109 at the time of engagement of the clutch 106. This influence may be accomplished by controlling fuel supplied to the internal combustion engine 101 to control the speed of rotation towards the desired speed rotation, which may e.g. be the current speed of rotation of the gearbox input shaft 103. When influencing the speed of rotation of the internal combustion engine101, the speed of change, i.e. change in fuel supply may be determined e.g. in dependence of how much the speed of rotation is to be changed and/or how fast the gearbox input shaft changes speed. Furthermore, it may be ensured that it is only the speed of rotation of the internal combustion engine 101 that is influenced and not the transmission of torque from the power source. In this way it may be ensured that the power source does not deliver more torque than is expected by the driver.

An expected speed of rotation of the gearbox input shaft 109 when the clutch engages may be estimated, and this expected speed of rotation may be determined e.g. from changes in time in speed of rotation of the gearbox input shaft and speed of closing of the clutch, i.e. the speed at which the driver manoeuvers the clutch pedal 118.

The time at which the clutch engages may be, for example, when the friction plate 106 contacts the flywheel 102. The engagement may also be a position where the friction plate contacts the flywheel 102 to an extent where some predetermined torque is transmittable.

When determining a point in time at which the clutch will engage a clutch characteristic may be used to determine when and to which extent the clutch will engage, Fig. 3 illustrates an example of a characteristic Pchar1for an exemplary clutch of a kind that may be used in a vehicle of Fig. 1 A. The y-axis denotes transmittable torque T, i.e. the torque that the clutch 106 can transmit between combustion engine 101 and gearbox 103 input shaft. In general, with regard to clutch characteristics, the x-axis denotes clutch position, such as clutch actuator position and/or lever arm position. The x-axis may also represent clutch pedal 118 position.

The origin, “0”, represents the clutch open position, i.e. a position where the clutch pedal 118, and usually friction element (the lever arm/the clutch actuator) is at its one extreme position, position B in Fig. 1C. This corresponds to a fully depressed clutch pedal 118, and the friction element 110 being completely disconnected from the combustion engine 101, i.e. being positioned to the right as in Fig. 1A. Conversely, the “closed clutch” position represents a fully released clutch pedal. That is, position A in Fig. 1C, and the friction element 110 being as close to the flywheel as possible and thereby pressed against the flywheel, for example by the aid of a spring action. Tmax represents the maximum torque that can be transmitted. The friction element 110, when the clutch is fully open, is normally at a distance from the engine's flywheel so that closing of the clutch involves the friction element, and hence the clutch pedal, initially moving a distance x1 before actually contacting the flywheel. Once the friction element precisely contacts the flywheel, at the contact point CP, torque transfer between the engine and rest of the powertrain can commence. The more the clutch closes from this point (i.e. the more strongly the friction element 110 engages the flywheel 102, the more torque can be transmitted over the clutch 106.

Flence, a characteristic of the kind shown in fig. 3 may be used to determine when the clutch will engage, and also when the clutch will transmit a torque that will equal or exceeds the torque that will be transmitted by the drivetrain, and hence render speed of rotation of the internal combustion engine and the gearbox input shaft synchronised. Also, by monitoring the speed at which the clutch pedal closes, e.g. from the signals representing clutch pedal position, it may be determined, e.g. through the use of a characteristic according to fig. 3 and estimation of the torque to be transmitted as discussed above, the point in time at which the clutch will engage to the extent where the speeds of rotation will be synchronised. The speed of rotation of the internal combustion engine 101 may then be influenced based on this determination.

If the gearbox input shaft speed changes e.g. if the vehicle being in an inclined section of road, such as when starting in a downhill, and e.g. is accelerating with open clutch, the input shaft speed at the estimated time of engagement may also be estimated by estimating the acceleration of the gearbox input shaft and the expected time of engagement so that the speed of rotation of the internal combustion engine may be controlled in dependence of this estimation.

If the driver is e.g. manoeuvring an accelerator in an attempt to synchronise the internal combustion engine with the gearbox input shaft the driver request for power may be influenced so that the speed of rotation of the internal combustion engine 101 will be better synchronised with the speed of rotation of the gearbox 103 input shaft 109.

In step 205 it is determined whether influence of the speed of rotation of the internal combustion engine is to be continued, e.g. in case the clutch still is not engaged and/or because the difference is better rotation still is above some predetermined threshold. If influence of the speed of rotation is to be continued, the method returns to step 204, while if it is determined that the speed of rotation of the internal combustion engine no longer is to be influenced, e.g. due to the clutch having engaged, the method is ended in step 206. According to embodiments of the invention, consequently, the difference in speed of rotation between the internal combustion engine 109 and gearbox 103 input shaft 109 when the clutch is engaged may be reduced to thereby reduce jerks and/or drivetrain oscillations that otherwise may occur. This may both increase driver comfortability and reduce wear of vehicle components.

Further, when engaging torque transmitting means when the vehicle is in motion, the driver often times attempts to synchronize the speed of rotation of the power source with the speed of rotation of the gearbox input shaft. According to embodiments of the invention, it is determined a driver requested speed of rotation of the power source, i.e. the speed of rotation to which the power source is controlled by the driver. Further, the speed of rotation of the internal combustion engine 101 may be controlled such that it deviates at most a predetermined number of revolutions per minute (rpm) from the driver requested speed of rotation. In this way, the difference in speed of rotation between the actual speed of rotation of the power source and the speed of rotation as expected by the driver may be controlled to obtain a vehicle behaviour that does not deviate to an extent that may confuse the driver. In this way, the difference in speed of rotation between the actual speed of rotation of the power source and the speed of rotation as expected by the driver may be controlled to obtain a vehicle behaviour that does not deviate to an extent that may confuse the driver.

As exemplified above, the speed of rotation of the internal combustion engine may be controlled for as long as the clutch is not engaged. This also means that the speed of rotation of the internal combustion may be arranged to follow the speed of rotation of the gearbox input shaft in case the latter is changing, e.g. due to variations in the road inclination. Hence the speed of rotation of the internal combustion engine may be both increased and decreased when influencing the speed of rotation of the internal combustion engine. Also, the speed of rotation may be influenced to be increased or decreased in relation to the speed of rotation of the internal combustion engine that is requested by the driver by means of e.g. the accelerator.

Furthermore, in addition to controlling the speed of rotation of the internal combustion engine, the clutch may be controlled. Since the clutch is controlled on the basis of a signal representing the position of the clutch pedal, it is possible to advance or retard closing of the clutch in relation to the driver request in order to better synchronise speeds of rotation upon engagement. For example, if it is determined that it will not be possible to control the speed of the internal combustion engine to a desired speed before engagement, the closing of the clutch may be retarded by the vehicle control system to give more time to reach the desired speed, or a speed within some predetermined speed difference, of the internal combustion engine. The delay of engagement may also be such that engagement is delayed at most by a predetermined period of time in relation to time of engagement if controlled according to the clutch pedal, again to avoid vehicle behaviour that may appear confusing to the driver.

Furthermore, vehicles often times display a speed of rotation of the power source to the driver. According to embodiments of the invention, a speed of rotation of the power source may be displayed to the driver that more corresponds to the speed of rotation requested by the driver than does the actual speed of rotation of the power source. That is, it may be displayed a speed of rotation of the power source that deviates from the actual speed of rotation of the power source. The displayed speed of rotation may be closer to the speed of rotation requested by the driver. In this way, impacts on the driver expected vehicle behaviour may also be reduced.

Furthermore, according to embodiments of the invention, the speed of rotation of the internal combustion engine 101 is only influenced if it is determined that a driver of the vehicle controls the speed of rotation of the internal combustion engine 101 towards the speed of rotation of the gearbox 103 input shaft 109. That is, the speed of rotation of the internal combustion engine 101 is only influenced if it is determined that the driver already attempts to synchronize the speed of rotation of the internal combustion engine 101. According to embodiments of the invention, the speed of rotation of the internal combustion engine 101 is only influenced if the internal combustion engine 101 is idling, i.e. there is no driver request for higher internal combustion engine 101 speed. In this case, the invention may be utilized to avoid jerks/oscillations when the torque transmitting means are engaged.

Furthermore, as was stated above, embodiments of the invention are applicable also when the torque transmitting means is of designs other than a clutch, such as torque transmitting means comprising one or more electrical machines and suitable gearing. Designs of this kind may provide functionality of a clutch, where such functionality may be controlled by driver manoeuvrable means e.g. in the form of a pedal. An example of a system of this kind is disclosed in the International application PCT/SE16/050538, with the title “A drive system for a vehicle” and having the same applicant as the present application. This referenced application is incorporated herein by reference.

In systems of this kind, an internal combustion engine may e.g. be connected to a gearbox input shaft through a planetary gearing, where an electrical machine is also connected to the planetary gearing. The internal combustion engine may be connected e.g. to a sun gear of the planetary gearing, while the gearbox may be connected to a carrier, and the electrical machine is connected to a ring gear.

According to solutions of the referenced application, the internal combustion engine may be rotating independently from the speed of rotation of the gearbox input gear.

Further, the electrical machine and internal combustion engine may be arranged in a torque balanced relationship such that when no torque is applied by the electrical machine, this limits the torque that can be transmitted by the internal combustion engine to zero.

When applied torque is increased by the electrical machine, a higher torque can be transmitted by the internal combustion engine to the gearbox input shaft, and the higher the transmission of torque the closer the speeds of rotation will be. When the electrical machine applies a torque equal to or exceeding the torque that will be transmitted by the drivetrain the speeds of rotation of the internal combustion engine and gearbox will be in synchronisation.

Consequently, the speed of rotation of the power source may be influenced according to embodiments of the invention also in systems of this kind when engaging the torque transmitting means, such as when increasing the torque applied by the electrical machine in response to e.g. a driver manoeuvred pedal that provides functions similar to that of a clutch pedal. The vehicle may be a hybrid vehicle, such as an electric hybrid vehicle, or any other kind of vehicle having torque transmitting means of this kind.

Finally, embodiments of the present invention have been described above mainly for a particular example of a vehicle, but is applicable for any vehicle in which driver manoeuvrable means are used to control torque transmitting means. The torque transmitting means may be of any suitable kind comprising any kind of elements, such as a clutch or other kind of solution, for as long as the manoeuvring of the torque transmitting means may be accomplished independently from the manoeuvring of the driver manoeuvrable means.

Claims

1. Method for a vehicle (100), the vehicle (100) including: torque transmitting means (106) for selectively transmitting torque between a power source (101) and a gearbox (103) of the vehicle (100), and driver manoeuvrable means (118), wherein transmittable torque of the torque transmitting means (106) is controllable in dependence of an electrical signal representing a position of the driver manoeuvrable means (118), the method including, when the vehicle is in motion: - detecting if engagement of the torque transmitting means (106) is initiated by means of the driver manoeuvrable means (118), and - if detecting said initiation of engagement of the torque transmitting means (106), influencing a speed of rotation of the power source (101) towards a speed of rotation of an input shaft (109) of the gearbox (103), wherein the method further includes estimating a speed of rotation of the input shaft (109) of said gearbox (103) at a time of engagement of the torque transmitting means (106), and influencing the speed of rotation of said power source (101) based on said estimation.

2. Method according to claim 1, wherein initiation of the engagement of the torque transmitting means (106) is detected if: - detecting a movement of the driver manoeuvrable means (118) from a position (B) representing a complete interruption of the transmission of torque towards a position (A) representing a request for a full transmissibility of torque.

3. Method according to any of the preceding claims, further including: - repeatedly determining a speed of rotation of the input shaft (109) of the gearbox (103), and - repeatedly control speed of rotation of said power source towards the determined speed of rotation of the input shaft (109) of the gearbox (103).

4. Method according to any one of the preceding claims, further including: - increasing the speed of rotation of the power source (101) if the speed of rotation of said input shaft (109) increases, and/or - decreasing the speed of rotation of the power source (101) if the speed of rotation of said input shaft (109) decreases.

5. Method according to any one of the preceding claims, further including: - controlling the torque transmitting means (106) such that an actual transmittable torque deviates from the transmittable torque as requested by the driver manoeuvrable means (118).

6. Method according to any one of the preceding claims, further including: - estimating if the torque transmitting means (106), if controlled according to the driver manoeuvrable means (118), will engage prior to the speed of rotation of the power source (101) reaches the speed of rotation of said input shaft (109), and - if it is estimated that said engagement of the torque transmitting means will occur prior to the speed of rotation of the power source (101) reaches the speed of rotation of said input shaft (109), delaying engagement of said torque transmitting means (106).

7. Method according to any one of the preceding claims, further including: - determining a driver requested speed of rotation of the power source (101), and - when influencing the speed of rotation of the power source (101), deviating at most a predetermined number of revolutions per minute (rpm) from the driver requested speed of rotation.

8. Method according to any one of the preceding claims, wherein the speed of rotation of the power source (101) is influenced if: - it is determined that a driver of the vehicle controls the speed of rotation of the power source towards the speed of rotation of the input shaft (109) of the gearbox (103), and/or - a current driver request for speed of rotation of the power source is an idling speed.

9. Method according to any one of the preceding claims, wherein the speed of rotation of the power source (101) is influenced if: - a gear for propulsion of the vehicle (100) is engaged in said gear box (103).

10. Method according to any one of the preceding claims, the driver manoeuvrable means being a clutch pedal (118).

11. Computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to any one of the preceding claims.

12. Computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any one of the claims 1-10.

13. System for a vehicle (100), the vehicle (100) including: torque transmitting means (106) for selectively transmitting torque between a power source (101) and a gearbox (103) of the vehicle (100), and driver manoeuvrable means (118), wherein transmittable torque of the torque transmitting means (106) is controllable in dependence of an electrical signal representing a position of the driver manoeuvrable means (118), the system including means for, when the vehicle is in motion: - detecting if engagement of the torque transmitting means (106) is initiated by means of the driver manoeuvrable means (118), - if detecting said initiation of engagement of the torque transmitting means (106), influencing a speed of rotation of the power source (101) towards a speed of rotation of an input shaft (109) of the gearbox (103); - estimating a speed of rotation of the input shaft (109) of said gearbox (103) at a time of engagement of the torque transmitting means (106), and influencing the speed of rotation of said power source (101) based on said estimation

14. Vehicle comprising a system according to claim 13.