SE542021C2

SE542021C2 - Method for shutting down a combustion engine of a vehicle powertrain, control device, vehicle, computer program and computer readable medium

Info

Publication number: SE542021C2
Application number: SE1850714A
Authority: SE
Inventors: Magnus Carlgren; Martin Berglund
Original assignee: Scania Cv Ab
Priority date: 2018-06-12
Filing date: 2018-06-12
Publication date: 2020-02-11
Also published as: SE1850714A1; DE102019003552A1

Abstract

The present disclosure relates to a method, performed by a control device 100, for shutting down a combustion engine 2 of a vehicle powertrain 3. The vehicle powertrain 3 comprises a combustion engine 2, a gearbox 4 and a clutch 9 arranged between the combustion engine and the gearbox. The method comprises engaging the clutch so as to provide a braking torque to the combustion engine, thereby shutting down the combustion engine. The disclosure also relates to a control device configured to shut down a combustion engine of a vehicle powertrain, as well as a vehicle comprising such a device. Furthermore, a computer program and a computer-readable medium are disclosed.

Description

METHOD FOR SHUTTING DOWN A COMBUSTION ENGINE OF A VEHICLE POWERTRAIN, CONTROL DEVICE, VEHICLE, COMPUTER PROGRAM AND COMPUTER READABLE MEDIUM TECHNICAL FIELD The present disclosure relates in general to a method for shutting down a combustion engine of a vehicle powertrain. The present disclosure also relates in general to a control device configured to shut down a combustion engine of a vehicle powertrain, as well as a vehicle comprising such a control device. Moreover, the present disclosure relates in general to a computer program and a computer-readable medium.

BACKGROUND Vehicle transmissions are designed to transmit torque from an engine to the driving wheels of the vehicle in order to propel the vehicle. The vehicle powertrain generally comprises a combustion engine, a gearbox arranged to selectively transfer torque between the combustion engine and the driving wheels, and a clutch arranged between the combustion engine and the gearbox.

Engine start and stop is becoming more and more frequent due to environmental legislations, in particular with regard to CO2 emissions. Today, combustion engines are often shut down by stopping fuel injection and/or cutting ignition. However, due to inertia of the engine, transition to standstill takes some time. During this transition period, unwanted oscillations may occur. Furthermore, noise from engine transmission, compression, and other constituent components of the powertrain may also occur. These oscillations and/or noise are uncomfortable for the driver and passengers of the vehicle. Therefore, there is a desire to overcome or at least reduce these oscillations and the noise caused when shutting down the combustion engine.

WO 2015/166819 discloses an internal combustion engine stop control device capable of reducing passenger discomfort related to vibration when the internal combustion engine stops. The control device performs a shift operation that switches the gear position to the highest position and a clutch operation that switches an automatic clutch to a transmission state when an engine stop instruction has been given.

Furthermore, in hybrid vehicles, it has previously been proposed to shut down the engine fast by using the electrical engine in order to overcome the above given problems. One example of such a solution is disclosed in JP 2009-204065 A.

SUMMARY The object of the present invention is to overcome or at least reduce the problem of oscillations and/or noise that occurs when stopping a combustion engine of a vehicle powertrain.

The object is achieved by the subject-matter of the independent claims.

The present invention provides a method, performed by a control device, for shutting down a combustion engine of a vehicle powertrain. The vehicle powertrain comprises a combustion engine having an outgoing shaft. The vehicle powertrain further comprises a gearbox arranged to selectively transfer torque between the combustion engine and at least one driving wheel, the gearbox comprising an input shaft and an output shaft. Moreover, the vehicle powertrain comprises a clutch arranged between the combustion engine and the gearbox, the clutch being connected to the input shaft of the gearbox and the outgoing shaft of the combustion engine. The method comprises the steps of: a) when an engine shut down event is commanded, securing the input shaft (10) of the gearbox (4) in a non-rotating state, if not already secured in the non-rotating state, by means of the gearbox (4); and b) engaging the clutch (9) so as to provide a braking torque to the outgoing shaft (7) of the combustion engine.

By means of the present invention, the engine can be shut down in a short period of time, faster than achievable by simply cutting ignition and/or stopping fuel injection. Therefore, the period during shut down, during which the combustion engine operates within a rotational speed range which can cause resonance by coinciding with the natural frequency of the adjacent components of the vehicle, can be very short. In fact, the duration can be so short that the oscillations causing the resonance will not even have sufficient time to be generated. Furthermore, the present method enables a softer engine shutdown. Thereby, less oscillations and noise will occur during shut down of the combustion engine, and can even be substantially avoided. The present method therefore provides increased comfort to the driver and potential passengers. These advantages are achieved without having to add any new hardware and thus presents a cost-efficient solution to the problem.

Moreover, in view of the fact that the input shaft is secured in a non-rotating state by means of the gearbox before engaging the clutch, the present method may avoid unnecessary torsional wind up of the driveline during shut down of the combustion engine.

The method disclosed above may further comprise a step of, before engaging the clutch so as to provide a braking torque to the outgoing shaft of the combustion engine, controlling the powertrain so as to disable transmission of torque from the input shaft of the gearbox to the at least one driving wheel. Thereby, the torsional forces to which the input shaft of the gearbox is subjected to will not be counteracted by the at least one driving wheel and therefore, less components of the powertrain will loaded when the clutch is engaged. This leads to less torsional wind up of the driveline which also gives less torsional oscillation seeking to provide a torsional return of the outgoing shaft of the combustion engine when the combustion engine has reached a zero rotational speed. Therefore, the clutch may be engaged until the combustion engine has been completely shut down. This inter alia leads to an easier control of the method for shutting down the combustion engine of the vehicle powertrain.

Controlling the powertrain so as to disable transmission of torque from the input shaft of the gearbox to the at least one driving wheel may comprise preventing torque transmission between the input shaft of the gearbox to the output shaft of the gearbox. Thereby, it is possible to shut down the combustion engine even before the vehicle is at complete standstill, if desired. This in turn leads to a more robust solution since the method is not sensitive to the vehicle being at complete standstill when the combustion engine is shut down. In fact, this would enable usage of the present method for shutting down the combustion engine irrespective of the traveling speed of the vehicle. Shutting down the combustion engine by means of the present method could therefore also be made at high traveling speeds of the vehicle if needed and/or desired.

The step of securing the input shaft of the gearbox in a non-rotating state by means of the gearbox may comprise activating at least one transmission brake of the gearbox. Gearboxes used today generally comprise at least one transmission brake, and therefore there is no need of adding additional components to the gearbox for enablement to secure the input shaft of the gearbox in a non-rotating state. When activating the at least one transmission brake of the gearbox, the transmission brake may provide a holding force preventing a shaft (of the gearbox) associated with the transmission brake from rotating. By engaging appropriate gears, if needed, the transmission brake may therefore be utilised to secure the input shaft of the gearbox in a non-rotating state.

Alternatively, or additionally, the step of securing the input shaft of the gearbox in a non-rotating state by means of the gearbox may comprise locking at least one shaft of the gearbox by means of a locking device adapted to selectively lock the at least one shaft of the gearbox in a non-rotating state. By utilising such a locking device, the input shaft of the gearbox can easily be firmly secured in a non-rotating state. In case the locking device is adapted to selectively lock a shaft of the gearbox other than the input shaft of the gearbox, the input shaft of the gearbox may be secured in a nonrotating state by means of the locking device by engaging appropriate gears connecting the shaft associated with the locking device with the input shaft of the gearbox. In case the locking device is adapted to selectively lock the input shaft of the gearbox, there is no need for engaging any gears of the gearbox. Thereby, the torsional wind up, as discussed above, can be even further reduced.

Alternatively, the step of securing the input shaft of the gearbox in a non-rotating state by means of the gearbox may comprise engaging a first gear of the gearbox and engaging a second gear of the gearbox so that the first gear and the second gear are engaged simultaneously. Since a first gear and a second gear are engaged simultaneously, the shafts of the gearbox are unable to rotate which in turn leads to the input shaft of the gearbox being secured in a non-rotating state.

The method may further comprise a step of disengaging the clutch before the combustion engine is completely shut down. Thereby, it is possible to avoid that a possible torsional wind up of the driveline acting on the combustion engine when the combustion engine has reached a zero rotational speed. Thus, it may lead to less risk for damage of the clutch.

The method may further comprise a step of, when an engine shut down event is commanded, stopping fuel injection to the combustion engine and/or cutting ignition of the combustion engine. The step of cutting fuel injection and/or cutting ignition may be performed before, at the same time or after engaging the clutch so as to provide a braking torque to the combustion engine. This has the advantage of enabling use of the clutch providing a braking torque to the outgoing shaft of the combustion engine only for a part of the duration of the shutting down of the combustion engine, if desired. For example, the clutch could be used only for passing the rotational speed range of the outgoing shaft of the combustion engine which may cause the resonance. Furthermore, it may lead to a softer shut down of the combustion engine.

The present disclosure also relates to a control device configured to shut down a combustion engine of a vehicle powertrain, the vehicle powertrain comprising: a combustion engine having an outgoing shaft, a gearbox arranged to selectively transfer torque between the combustion engine and at least one driving wheel, the gearbox comprising an input shaft and an output shaft, and a clutch arranged between the combustion engine and the gearbox, the clutch connected to the input shaft of the gearbox and the outgoing shaft of the combustion engine; wherein the control device is configured to, when an engine shut down event has been commanded, control the gearbox to secure the input shaft of the gearbox in a non-rotating state, if not already secured in the non-rotating state, the control device further configured to engage the clutch, when the input shaft of the gearbox is secured in the non-rotating state, so as to provide a braking torque to the outgoing shaft of the combustion engine.

Thus, by means of the control device, the combustion engine of the vehicle powertrain can be shut down fast and smoothly. This has the advantages described above with regard to the method for shutting down a combustion engine of a vehicle powertrain.

The control device may furthermore be configured to, when an engine shut down event is commanded, control the powertrain so as to disable transmission of torque from the ingoing shaft of the gearbox to the at least one driving wheel, before engaging the clutch so as to provide a braking torque to the outgoing shaft of the combustion engine. Thereby, less torsional wind up may be achieved when the combustion engine is shut down.

The control device may further be configured to disengage the clutch before the combustion engine is completely shut down, if desired.

The present disclosure furthermore relates to a vehicle comprising a vehicle powertrain, the vehicle powertrain comprising: a combustion engine having an outgoing shaft, a gearbox arranged to selectively transfer torque between the combustion engine and at least one driving wheel, the gearbox comprising an input shaft and an output shaft, and a clutch arranged between the combustion engine and the gearbox, the clutch connected to the input shaft of the gearbox and the outgoing shaft of the combustion engine.

The vehicle further comprises a control device configured to shut down a combustion engine of a vehicle powertrain as disclosed above.

The present disclosure also relates to a computer program, wherein said computer program comprises program code for causing a control device or a computer connected to the control device to perform the method, as disclosed above, for shutting down a combustion engine of a vehicle powertrain.

Moreover, the present disclosure relates to a computer-readable medium comprising instructions , which when executed by a control device or a computer connected to the control device, cause the control device or the computer to perform the method, as disclosed above, for shutting down a combustion engine of a vehicle powertrain.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 schematically illustrates a side view of a vehicle; Fig. 2 schematically illustrates a first exemplifying embodiment of a vehicle powertrain; Fig. 3a represents a flow chart schematically illustrating a method for shutting down a combustion engine of a vehicle powertrain in accordance with one exemplifying embodiment; Fig. 3b represents a flow chart schematically illustrating a method for shutting down a combustion engine of a vehicle powertrain in accordance with another exemplifying embodiment; Fig. 4 schematically illustrates a second exemplifying embodiment of a vehicle powertrain; Fig. 5 schematically illustrates a third exemplifying embodiment of a vehicle powertrain; Fig. 6 schematically illustrates a device which may constitute, comprise or be a part of a control device configured to shut down a combustion engine of a vehicle powertrain.

DETAILED DESCRIPTION The invention will be described in more detail below with reference to exemplifying embodiments and the accompanying drawings. The invention is however not limited to the exemplifying embodiments discussed and/or shown in the drawings, but may be varied within the scope of the appended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate the invention or features thereof.

The present disclosure relates to a method, performed by a control device, for shutting down a combustion engine of a vehicle powertrain. The powertrain comprises a combustion engine having an outgoing shaft, and a gearbox arranged to selectively transfer torque between the combustion engine and at least one driving wheel, the gearbox comprising an input shaft and an output shaft. The powertrain further comprises a clutch arranged between the combustion engine and the gearbox. The clutch is connected to the input shaft of the gearbox and the outgoing shaft of the combustion engine. Thus, when the clutch is engaged, torque may be transmitted from the combustion engine to the gearbox whereas when the clutch is not engaged, torque may not be transmitted from the combustion engine to the gearbox.

The method for shutting down a combustion engine of a vehicle powertrain according to the present disclosure comprises a step of securing, if not already secured, the input shaft of the gearbox in a state wherein the input shaft is not rotating when an engine shut down event is commanded. In the present disclosure, the terms "securing", "secured" and the like are used for describing that a component (in this case the input shaft) is purposively held in a certain state by other means than the component itself or that such means are activated for holding the component in such a state, respectively. Thus, securing the input shaft in a non-rotating state shall be considered to mean holding the input shaft, by means of another device or arrangement (such as a securing arrangement as will be described further below), such that the input shaft is unable or essentially unable to rotate.

The method further comprises a step of, when the input shaft of the gearbox is secured in a nonrotating state, engaging the clutch. Since the input shaft is secured in a non-rotating state, engagement of the clutch will provide a braking torque to the outgoing shaft of the combustion engine. This braking torque will therefore cause a decrease in the rotational speed of the outgoing shaft of the combustion engine. Thereby, the combustion engine may be shut down.

An engine shut down event may be commanded as known in the art. For example, an engine shut down may be commanded by a driver of the vehicle, for example by turning off an ignition switch of the vehicle. Alternatively, an engine shut down event may be commanded by an engine control system configured to automatically shut down the combustion engine. Such a system may for example be configured to automatically shut down the combustion engine when the vehicle is at standstill for a predetermined minimum time, for example when stopping at traffic lights, when stopping for a road bridge opening, or the like. The commanded engine shut down event, irrespectively of how it is commanded (i.e. its origin), may be detected by the control device configured to shut down the combustion engine. Alternatively, the control device may itself comprise a control system configured to automatically shut down a combustion engine, in which case the control device may also be configured to generate the command for the engine shut down event when predetermined conditions predefined to generate an engine shut down event command by the control device have been detected.

The method for shutting down the combustion engine of the vehicle powertrain may further comprise a step of, before engaging the clutch so as to provide a braking torque to the outgoing shaft of the combustion engine, controlling the powertrain so as to disable transmission of torque from the input shaft of the gearbox to the at least one driving wheel. Disabling transmission of torque from the input shaft of the gearbox to the at least one driving wheel may be achieved by any conventional means. In other words, any component of the driveline, which can be disengaged so that transmission of torque to the driving wheels is disabled, may be used for this purpose. When a transmission of torque from the input shaft of the gearbox to the driving wheels is disabled, less components of the driveline of the vehicle powertrain will be loaded when the input shaft is secured in a non-rotating state and the clutch is engaged so that a braking torque is provided to the outgoing shaft of the combustion engine. Thus, fewer components of the driveline of the vehicle powertrain will experience a torsional wind up. This in turn leads to less torsional oscillation seeking to reverse the outgoing shaft of the combustion engine when the outgoing shaft of the combustion engine has reached a zero rotational speed. With such a small wind up, the clutch can be kept engaged until the engine has been completely shut down, which in turn leads to an easier control of the clutch and thus also of the method for shutting down the combustion engine per se. Therefore, this may also lead to more consistent and predicable results of the method for shutting down the combustion engine.

Controlling the powertrain so as to disable transmission of torque form the input shaft of the gearbox to the at least one driving wheel may comprise disabling torque transmission from the input shaft of the gearbox to the output shaft of the gearbox. Thereby, only constituent components of the gearbox may be subjected to the torsional wind up.

The method for shutting down a combustion engine is performed by a control device configured to shut down the combustion engine of the vehicle powertrain. The control device is configured to, when an engine shut down event is commanded, control the gearbox to secure the input shaft in a non-rotating state, if not already secured in the non-rotating state. The control device is further configured to engage the clutch, when the input shaft of the gearbox is secured in the non-rotating state. Thereby, the clutch provides a braking torque to the outgoing shaft of the combustion engine. The control device may further be configured to perform any of the steps of the method for shutting down a combustion engine as disclosed herein.

Figure 1 schematically illustrates a side view of an example of a vehicle 1. The vehicle 1 comprises a powertrain 3 comprising an internal combustion engine 2 and a gearbox 4. A clutch (see figure 2) is arranged between the internal combustion engine 2 and the gearbox 4. The gearbox 4 is connected to the driving wheels 5 of the vehicle 1 via an output shaft 6 of the gearbox 4. The gearbox 4 is adapted to selectively transfer torque between the combustion engine 2 and the driving wheels 5 during operation of the vehicle.

The vehicle 1 may be, but is not limited to, a heavy vehicle, e.g. a truck or a bus. Furthermore, the vehicle may be a hybrid vehicle comprising an electric machine (not shown) in addition to the internal combustion engine 2.

Figure 2 schematically illustrates a first exemplifying embodiment of a vehicle powertrain 3, such as a powertrain of the vehicle 1 shown in Figure 1. The powertrain 3 comprises the combustion engine 2, a gearbox 4 and a clutch 9 arranged between the combustion engine 2 and the gearbox 4. The gearbox may be an automated manual gearbox (AMT). The clutch 9 may be a friction clutch. The internal combustion engine 2 comprises an outgoing shaft 7 connected to the clutch 9. The gearbox 4 comprises an input shaft 10 connected to the clutch 9 and an output shaft 6 connected to the driving wheels 5. The vehicle powertrain may furthermore comprise a control device 100, as will be described in more detail below. The control device 100 is adapted to control at least a part of the powertrain. More specifically, the control device is adapted to control the clutch 9 as well as the gearbox 4, or at least a part thereof.

The gearbox may further comprise a securing arrangement 11 which, when activated, may secure the input shaft 10 of the gearbox 4 in a non-rotating state. The securing arrangement 11 may for example comprise a transmission brake of the gearbox and/or a locking device adapted to selectively lock at least one shaft of the gearbox in a non-rotating state. The securing arrangement 11 may alternatively comprise, when activated, two gears engaged simultaneously. These various securing arrangements will be exemplified further below with reference to Figures 4 and 5.

Figure 3a represents a flowchart schematically illustrating a method for shutting down a combustion engine of a vehicle powertrain according to one exemplifying embodiment of the present disclosure. The method shown in Figure 3a may for example be performed for the vehicle powertrain shown in Figure 2. The method comprises a first step, sllO, of securing the input shaft of the gearbox in a nonrotating state, if not already secured in the non-rotating state, by means of the gearbox when an engine shut down event has been commanded. The method further comprises a second step, sl20, of engaging the clutch, when the input shaft of the gearbox is secured in the non-rotating state, thereby providing a braking torque to the outgoing shaft of the combustion engine. The braking torque is achieved in view of the input shaft of the gearbox being in a non-rotating state, which thereby seeks to reduce the rotational speed of the outgoing shaft when the clutch is engaged.

Figure 3b represents a flowchart schematically illustrating a method for shutting down a combustion engine of a vehicle powertrain according to another exemplifying embodiment. The method shown in Figure 3b corresponds to the method of Figure 3a except that it also comprises a step, slOO, of controlling the powertrain so as to disable transmission of torque from the input shaft of the gearbox to the at least one driving wheel. The step slOO may preferably be performed before step sllO as shown in Figure 3b, since this minimizes the torsional wind up of the driveline. Flowever, it is also possible to perform step slOO at the same time as step sllO or even after step sllO. Step slOO is however to be performed before the step sl20 of engaging the clutch.

Figure 4 schematically illustrates a second exemplifying embodiment of a vehicle powertrain. The powertrain 3 comprises a combustion engine 2, a gearbox 4 and a clutch 9 arranged between the combustion engine 2 and the gearbox 4. The gearbox 4 comprises an input shaft 10 connected to the clutch 9 and an output shaft 6 connected to the driving wheels 5. The gearbox 4 comprises a first gearbox unit 4A and a second gearbox unit 4B arranged downstream of the first gearbox unit 4A. The first gearbox unit may be a split gearbox unit. The second gearbox unit may constitute a conventional main gearbox that can be set to a number of different forward gear ratios. The second gearbox unit 4B is connectable to the first gearbox unit 4A. While not shown in Figure 4, the gearbox may optionally comprise additional gearbox units as known in the art, for example a range gearbox arranged downstream of the second gearbox unit. The powertrain may also for example comprise a retarder.

The second gearbox unit 4B comprises a lay shaft 20 with gear wheels 12B, 13B, 14B, 15B that are rotatably fixed to the lay shaft 20. For example, gear wheel 12B may represent the first gear, gear wheel 13B may represent the second gear, and gear wheel 14B may represent the third gear. The second gearbox 4B also comprises a main shaft 30 with corresponding gear wheels 12A, 13A, 14A which rotate freely in relation to the main shaft 30, but which can be selectively locked for rotation with the main shaft 30 in order to engage a gear. When each of the gear wheels 12A, 13A, 14A rotate freely in relation to the main shaft 30, the second gearbox unit 4B is in neutral. Thereby, no torque is transmitted from the combustion engine 2 to the driving wheels 5. The gear wheels 12A, 13A, 14A on the main shaft 30 may be locked by means of corresponding sleeves 16, 17, 18. For example, the first gear in the second gearbox 4B can be engaged by maneuvering the first sleeve 16, arranged to rotate with the main shaft 30, to a position where the gear wheel 12A is engaged, i.e. to the left in the figure. The gear wheel 12A will thereby rotate with the main shaft 30, and the lay shaft 20 will thereby be connected to the main shaft 30 via gear wheel 12B. Each pair of gear wheels on the lay shaft 20 and main shaft 30 represents a gear ratio. The second gear in the second gearbox unit 4B may be engaged by disengaging the first sleeve 16 from the gear wheel 12A and instead moving a second sleeve 17 to a position to the right in the figure where, instead, gear wheel 13A is engaged. The gear wheel 13A is thereby brought into rotation with the main shaft 30. Correspondingly, the third gear in the second gearbox unit 4B may be engaged by maneuvering the second sleeve 17 to the left in the figure where, instead, gear wheel 14A is engaged. Each of the first through third gears in the second gearbox unit 4B is used for a plurality of the total number of gears provided by the gearbox 4 as a whole. The second gearbox unit 4B may further comprise a reverse gear (not shown) and a crawler gear (not shown).

The lay shaft 20 further comprises an additional gear wheel 15B that, similar to the above, is rotatably fixed to the lay shaft 20. The first gearbox unit 4A comprises a corresponding gear wheel 15A rotating freely in relation to the input shaft 10, but which may be selectively locked for rotation with the input shaft 10 through a split sleeve 18. When the split sleeve 18 locks the gear wheel 15A with the input shaft 10, torque can be transferred to the lay shaft 20 via the corresponding gear wheel 15B on the lay shaft 20. The split sleeve 18 can further be used to connect the input shaft 10 to the gear wheel 14A of the second gearbox unit 4B directly. This way, depending on whether the gear wheel 14A on the main shaft 30 is rotating freely in relation to the main shaft 30 or if it is locked on the main shaft 30, torque can be transferred to the lay shaft 20 via the corresponding gear wheel 14B on the lay shaft 20 or torque can be transferred from the input shaft 10 directly to the main shaft 20. The gear wheel pair 15A/15B and the split sleeve 18 can thereby be used to provide two different split gear ratios for each gear of the second gearbox unit 4B. The first gearbox unit 4A may thus be controlled to engage a high-split gear or a low-split gear. For example, engaging the low-split gear may comprise to connect the input shaft 10 with the low gear wheel 14A on the main shaft 30 by means of the split sleeve 18. When e.g. the first gear is engaged in the second gearbox unit 4B, the split sleeve 18 may be arranged to engage gear wheel 14A. This way, the input shaft 10 is directly connected to gear wheel 14B, which via gear 14B establishes a first gear ratio between the input shaft 10 and the lay shaft 20. The gear wheel 14A, however, is not locked to the main shaft 20, but the lay shaft 20 may be connected to the main shaft 20 through gear wheel pair 12A/12B. To engage the second gear, gear wheel pair 15A/15B is instead engaged, resulting in a second gear ratio between the input shaft and the lay shaft 20. The gear wheel 12A is still engaged by the first main sleeve 16 according to the above, thereby extending the range of each gear. This split can be performed for each gear of the second gearbox unit 4B.

Each of the sleeves 16, 17, 18 described above may for example be operated by pneumatic actuators (not shown). Furthermore, the clutch 9 may be operated by a pneumatic actuator (not shown).

The gearbox 4 may comprise one or more transmission brakes, each transmission brake being connected to and configured to brake a corresponding shaft of the gearbox in order to control the rotational speed of such a shaft. In Figure 4, an input shaft transmission brake 22 and a lay shaft transmission brake 21 are shown. The input shaft 10 is provided with the input shaft transmission brake 22 for control of the rotational speed of the input shaft 10 during a gear shift. Correspondingly, lay shaft 20 is provided with a lay shaft transmission brake 21 for control of the rotational speed of the lay shaft during a gear shift. The gearbox may however comprise only one of the transmission brakes shown or more than two transmission brakes. For example, while not shown in Figure 4, the gearbox may also comprise a main shaft transmission brake.

Each of the transmission brakes 21, 22 may for example be pneumatically controlled. The transmission brakes may for example constitute a part of a synchronization arrangement of the gearbox. The purpose of a synchronization arrangement is to synchronize the rotational speeds of the shafts for effectuating gear changes.

The powertrain 3 may furthermore comprise a control device 100. The control device 100 may be configured to control the gearbox 4, or at least a part thereof, and the clutch 9. The control device may comprise one or more control units 70. In Figure 4, only one control unit 70 is illustrated. The control device 100 may further comprise a computer 72 connected to the control unit 70. The control unit(s) 70 and the computer 72 may each comprise a memory M and/or a computer program P which will be described in more detail below. The control device may be connected to one or more constituent components of the powertrain 3 via connections 70A. For ease of illustration, the connections 70A of the control device 100 have not been fully illustrated in Figure 4. The connections 70A may be physical connections or non-physical connections, as will be further described below. A control unit 70 of the control device 100 may be connected to any part of the powertrain, such as the combustion engine 2, the clutch 9 and/or the gearbox 4, to control the operation of such a part of the powertrain. Alternatively, the combustion engine, the clutch and the gearbox may each comprise a separate control unit connected to the other control units of the control device directly or via a common control unit. The control device 100 may, if desired, be configured to control the whole powertrain 3 of the vehicle 1.

When an engine shut down even is commanded, the input shaft 10 of the gearbox 4 may be secured in a non-rotating state, if not already secured in the non-rotating state. Considering the vehicle powertrain 3 of Figure 4, securing the input shaft in a non-rotating state may comprise activating the input shaft transmission brake 22 such that the input shaft transmission brake 22 prevents the input shaft 10 of the gearbox from rotating. Alternatively, or additionally, the gear wheel pair 15A/15B may be engaged and the lay shaft transmission brake activated so as to prevent the lay shaft from rotating. Since the lay shaft 20 is unable to rotate and the gear wheel pair 15A/15B is engaged, the input shaft will be prevented from rotating by means of the lay shaft transmission brake 21. In case of the gearbox comprising a main shaft transmission brake, the main shaft transmission brake may be utilized for securing the input shaft in a non-rotating state for example by engaging gear wheel pairs 15A/15B and at least one of the gear wheel pairs 12A/12B, 13A/13B and 14A/14B.

Alternatively, the split sleeve 18 may be arranged so as to directly connect the input shaft 10 with the main shaft 30 of the gearbox as described above. In such a case, the main shaft transmission brake will, by preventing the main shaft 30 from rotating, also prevent the input shaft 10 from rotating.

Although transmission brakes of gearboxes in general are configured to brake a corresponding shaft of the gearbox, they may also be used for securing the input shaft of the gearbox 4 in a non-rotating state when shutting down the combustion engine. This is inter alia because the rotational speed of the shafts of the gearbox in general are very low when an engine shut down event is commanded. Therefore, the transmission brakes are also able to provide a holding force preventing a shaft associated with the transmission brake from rotating.

The input shaft 10 may alternatively be secured in a non-rotating state by engaging a first gear, corresponding to a first gear ratio of the gearbox, and engaging a second gear, corresponding to a second gear ratio of the gearbox, such that said first and second gears are engaged simultaneously. By having two gears engaged simultaneously, a shaft associated with the gears will be unable to rotate since the two gears are configured for different rotational speeds of said shaft. Considering the exemplified gearbox 4 shown in Figure 4, two gears may be engaged simultaneously by engaging the gear wheel pair 15A/15 as well as two of the following gear wheel pairs: 12A/12B, 13A/13B and 14A/14B. Alternatively, the split sleeve 18 may be arranged such that the input shaft 10 and the main shaft 30 are directly connected. In such a case, two gears may be engaged simultaneously by engaging two of the following gear wheel pairs: 12A/12B, 13A/13B, 14A/14B and 15A/15B.

Figure 5 illustrates a third exemplifying embodiment of a vehicle powertrain 3. The powertrain 3 comprises a combustion engine 2, a gearbox 4 and a clutch 9 arranged between the combustion engine 2 and the gearbox 4. The gearbox 4 comprises an input shaft 10 connected to the clutch 9 and an output shaft 6 connected to the driving wheels 5. The gearbox 4 comprises a first gearbox unit 4A and a second gearbox unit 4B arranged downstream of the first gearbox unit 4A. The first gearbox unit 4A and the second gearbox unit 4B are configured as described above with regard to the exemplifying embodiment shown in Figure 4. It should be noted that while only a lay shaft transmission brake 21 is illustrated in Figure 5, the gearbox 4 may comprise any of the transmission brakes described above with regard to the exemplifying embodiment shown in Figure 4 in addition to or in alternative to the lay shaft transmission brake 21. The powertrain further comprises a control device 100. The control device 100 may for example be a control device such as disclosed above with reference to Figure 4.

In contrast to the exemplifying embodiment illustrated in Figure 4, the exemplifying embodiment of Figure 5 comprises a first locking device configured to selectively lock the input shaft 10 of the gearbox 4 in a non-rotating state, and a second locking device configured to selectively lock the lay shaft 20 of the gearbox in a non-rotating state.

The first locking device comprises a locking wheel 32 configured to rotate with the input shaft 10 of the gearbox 4. The first locking device furthermore comprises a sleeve 33 associated with the locking wheel 32. The sleeve 33 is movable between a first position (shown in Figure 5) wherein the locking wheel 32 freely rotates with the input shaft 10, and a second position (not shown) wherein it engages a corresponding mating feature 34a associated with the gearbox housing 34. In the first position of the sleeve 33, the first locking device is in a non-activated state. When the sleeve is in the second position, it locks the locking wheel 32 against the mating feature 34a, thereby preventing the locking wheel 32 from rotating. When the locking wheel 32 is unable to rotate, the input shaft 10 is inherently prevented from rotation. Thus, by activating the first locking device, the input shaft 10 may be secured in a non-rotating state.

In the corresponding manner as described above with regard to the first locking device, the second locking device comprises a locking wheel 35 connected to the lay shaft 20 of the gearbox 4 so as to rotate therewith. The second locking device further comprises a sleeve 36 associated with the locking wheel 35. The sleeve 36 is movable between a first position (shown in Figure 5) wherein the locking wheel 35 freely rotates with the lay shaft 20, and a second position (not shown) wherein the sleeve 36 engages a corresponding mating feature 34b of the gearbox housing 34 such that the locking wheel 35 is connected to the mating feature 34b. When the sleeve 36 is in the second position so as to connect the locking wheel 35 with the mating feature 34b, the locking wheel 35 is prevented from rotating. Thereby, the lay shaft 20 is inherently prevented from rotating when the second locking device is activated. By engaging the gear wheel pair 15A/15B, the lay shaft 20 and the input shaft 10 are connected, which in turn leads to the second locking device inherently also preventing the first shaft from rotating. Thus, by activating the second locking device and engaging the gear wheel pair 15A/15B, the input shaft of the gearbox may be secured in a non-rotating state.

It should be readily noted that while Figure 5 illustrates a first locking device and a second locking device, the gearbox 4 need not comprise both these locking devices. Furthermore, the gearbox 4 may comprise additional locking devices, such as a locking device with essentially a corresponding configuration as described above but being associated with the main shaft 30.

The locking device need not have the configuration described above and shown in Figure 5. Any previously known locking device configured to selectively lock one shaft of a gearbox may be used in the method according to the present disclosure.

Figure 6 schematically illustrates an exemplifying embodiment of a device 500. The control device 100 described above, comprising one or more control units 70 and/or the computer 72, may in a version comprise the device 500. Alternatively, the control device 100 may be comprised in the device 500.

The term "link" refers herein to a communication link which may be a physical connection such as an optoelectronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.

The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500. The nonvolatile memory 520 may also have a second memory element 540. According to an alternative embodiment, the non-volatile memory 520 may be replaced by a volatile memory (not depicted).

The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted).

There is provided a computer program P which comprises routines for shutting down a combustion engine of a vehicle powertrain, the vehicle powertrain comprising a combustion engine, a gearbox and a clutch arranged between the combustion engine and the gearbox. The computer program P comprises routines for securing an input shaft of the gearbox in a non-rotating state, if not already secured, when an engine shut down event is commanded. The computer program P also comprises routines for, when the input shaft of the gearbox is secured in a non-rotating state, engaging a clutch of the vehicle powertrain so as to provide a braking torque to an outgoing shaft of the combustion engine.

The program P may be stored in an executable form or in a compressed form in a memory 560 and/or in a read/write memory 550. Each of the memory 560 and the read/write memory 550 may be in the form of a non-volatile memory or a volatile memory, such as a cloud.

Where the data processing unit 510 is described as performing a certain function, it means that the data processing unit 510 effects a certain part of the program stored in the memory 560 or a certain part of the program stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The nonvolatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511. The read/write memory 550 is adapted to communicate with the data processing unit 510 via a data bus 514.

When data are received on the data port 599, they may be stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 is prepared to effect code execution as described above.

Parts of the methods herein described may be effected by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, methods herein described are executed.

Claims

1. A method, performed by a control device (100), for shutting down a combustion engine (2) of a vehicle powertrain (3), the vehicle powertrain (3) comprising: a combustion engine (2) having an outgoing shaft (7), a gearbox (4) arranged to selectively transfer torque between the combustion engine (2) and at least one driving wheel (5), the gearbox comprising an input shaft (10) and an output shaft (6), and a clutch (9) arranged between the combustion engine (2) and the gearbox (4), the clutch (9) connected to the input shaft (10) of the gearbox and the outgoing shaft (7) of the combustion engine (2); the method comprising the steps of: a) when an engine shut down event is commanded, securing (sllO) the input shaft (10) of the gearbox (4) in a non-rotating state, if not already secured in the non-rotating state, by means of the gearbox (4); and b) engaging (sl20) the clutch (9) so as to provide a braking torque to the outgoing shaft (7) of the combustion engine.

2. Method according to claim 1, further comprising, before engaging the clutch so as to provide a braking torque to the outgoing shaft of the combustion engine, controlling the powertrain so as to disable transmission of torque from the input shaft of the gearbox to the at least one driving wheel.

3. Method according to claim 2, wherein controlling the powertrain so as to disable transmission of torque from the input shaft of the gearbox to the at least one driving wheel comprises preventing torque transmission between the input shaft of the gearbox to the output shaft of the gearbox.

4. Method according to any one of the preceding claims, wherein securing the input shaft of the gearbox in a non-rotating state by means of the gearbox comprises activating at least one transmission brake of the gearbox.

5. Method according to any one of the preceding claims, wherein securing the input shaft of the gearbox in a non-rotating state by means of the gearbox comprises locking at least one shaft of the gearbox by means of a locking device adapted to selectively lock the at least one shaft of the gearbox in a non-rotating state.

6. Method according to any one of claims 1 to 3, wherein securing the input shaft of the gearbox in a non-rotating state by means of the gearbox comprises engaging a first gear of the gearbox and engaging a second gear of the gearbox so that the first gear and the second gear are engaged simultaneously.

7. Method according to any one of the preceding claims, further comprising a step of disengaging the clutch before the combustion engine is completely shut down.

8. Method according to any one of the preceding claims, further comprising, when an engine shut down event is commanded, stopping fuel injection to the combustion engine and/or cutting ignition of the combustion engine.

9. Control device (100) configured to shut down a combustion engine (2) of a vehicle powertrain (3), the vehicle powertrain comprising: a combustion engine having an outgoing shaft (7), a gearbox (4) arranged to selectively transfer torque between the combustion engine and at least one driving wheel (5), the gearbox comprising an input shaft (10) and an output shaft (6), and a clutch (9) arranged between the combustion engine and the gearbox, the clutch connected to the input shaft of the gearbox and the outgoing shaft of the combustion engine; the control device configured to, when an engine shut down event is commanded, control the gearbox to secure the input shaft of the gearbox in a non-rotating state, if not already secured in the non-rotating state, the control device further configured to engage the clutch, when the input shaft of the gearbox is secured in the non-rotating state, so as to provide a braking torque to the outgoing shaft of the combustion engine.

10. Control device according to claim 9, further configured to, when an engine shut down event is commanded, control the powertrain so as to disable transmission of torque from the ingoing shaft of the gearbox to the at least one driving wheel, before engaging the clutch so as to provide a braking torque to the outgoing shaft of the combustion engine.

11. Control device according to any one of claims 9 and 10, wherein the control device is configured to control the gearbox to secure the input shaft of the gearbox in a non-rotating state by one of the following: activating at least one transmission brake of the gearbox, locking at least one shaft of the gearbox by means of a locking device adapted to selectively lock the at least one shaft in a non-rotating state, or engaging a first gear of the gearbox and engaging a second gear of the gearbox so that the first gear and the second gear are engaged simultaneously.

12. Control device according to any one of claims 9 to 11, further configured to disengage the clutch before the combustion engine is completely shut down.

13. A vehicle (1) comprising a vehicle powertrain, the vehicle powertrain (3) comprising: a combustion engine (2) having an outgoing shaft (7), a gearbox (4) arranged to selectively transfer torque between the combustion engine (2) and at least one driving wheel (5), the gearbox comprising an input shaft (10) and an output shaft (6), and a clutch (9) arranged between the combustion engine (2) and the gearbox (4), the clutch (9) connected to the input shaft (10) of the gearbox and the outgoing shaft (7) of the combustion engine (2); the vehicle further comprising a control device (100) according to any of claims 9 to 12.

14. A computer program (P), wherein said computer program comprises program code for causing a control device (100) or a computer connected to the control device to perform the method according to any one of claims 1 to 8.

15. A computer-readable medium comprising instructions, which when executed by a control device (100) or a computer connected to the control device, cause the control device or the computer to perform the method according to any one of claims 1 to 8.