SE542971C2

SE542971C2 - Method for diagnosing a transmission brake, control device, vehicle, computer program and computer-readable medium

Info

Publication number: SE542971C2
Application number: SE1850663A
Authority: SE
Inventors: Daniel Häggström; Peer Norberg
Original assignee: Scania Cv Ab
Priority date: 2018-06-01
Filing date: 2018-06-01
Publication date: 2020-09-22
Also published as: SE1850663A1; BR102019010080A2; DE102019002943A1; DE102019002943B4

Abstract

A method for diagnosing a transmission brake (11, 21, 31, 41) of a gearbox (4) of a vehicle powertrain (3), the transmission brake being connected to and being configured to brake a first shaft (10, 20, 30) of the gearbox, is disclosed. The method comprises engaging a preselected system adding inertia to the first shaft, if not already engaged. Thereafter, the first shaft is braked by means of the transmission brake and the deceleration if the first shaft during said braking is detected. The detected deceleration of the first shaft is compared to one or more threshold values for the deceleration of the first shaft, thereby determining the performance of the transmission brake. The disclosure further relates to a control device configured to perform the method, as well as a vehicle, a computer program and a computer-readable medium.

Description

METHOD FOR DIAGNOSING A TRANSMISSION BRAKE, CONTROL DEVICE, VEHICLE, COMPUTERPROGRAM AND COMPUTER-READABLE MEDIUM TECHNICAL FIELD The present disclosure relates in general to a method for diagnosing a transmission brake of agearbox of a vehicle powertrain, more specifically to a method of determining the performance ofthe transmission brake. The present disclosure further relates in general to a control deviceconfigured to diagnose a transmission brake of a gearbox of a vehicle powertrain, and a vehiclecomprising such a control device. Moreover, the present disclosure relates in general to a computer program and a computer-readable medium.

BACKGROUND Modern heavy vehicles are often equipped with an automated manual gearbox (AMT). The AMTgearboxes are often of so-called "unsynchronized" type. This means that to shift gears, simple dogclutches are used to lock the intended gearwheel to the shaft, and transmission brakes and theengine are used to synchronize the speed between the gearwheel and the shaft before engagement of the dog clutch.

The transmissions brakes are normally pneumatic multi-disc brakes made of steel plates and frictiondiscs comprising a friction lining. The friction lining may for example be made of carbon compounds,carbon fiber or aramid fiber reinforced polymer, or bronze. The friction lining will over time degradedue to the number of brake cycles and the load, which in turn leads to a reduced friction. A reduced friction leads in turn to a reduced braking torque obtainable by the transmission brake.

There are also other factors that may influence the condition of the transmission brake. For example,in case of failure in the supply of air to the pneumatic actuator of the transmission brake, such as dueto leakage of air, the pressure may be insufficient to obtain the intended braking torque by the transmission brake. ln case a transmission brake is degraded or fails, the gearshift performance will be severely reduced.This may in turn lead to discomfort for the driver and/or passengers during a gearshift and can riskincreasing the wear of the constituent components of the gearbox. lt can even in though driving conditions lead to a situation where the gearbox completely fails and the vehicle no longer can be operated, and therefore has to stop immediately. This is sometimes referred to as a vehicle-off-road situation. lt is conceivable that the rate of degradation of a transmission brake over time could be monitoredand evaluated by considering the deceleration of the shaft on which the transmission brake acts. Theresult of such an evaluation could then for example be used to give notice to a preventivereplacement system that a change of brake discs is needed in order to avoid a vehicle-off-roadsituation. However, the retardation performance of the transmission brake is generally very high inorder to achieve a good gearshift performance. Therefore, it is difficult or even impossible to use thespeed sensors commonly used today to measure the deceleration with an accurate precision to make the evaluation of the result.

SUMMARY The object of the present invention is to enable diagnosing a transmission brake of a gearbox, more specifically the performance of the transmission brake, with a sufficient accuracy.

The object is achieved by the subject-matter of the appended independent claims. ln accordance with the present invention, a method for diagnosing a transmission brake of a gearboxof a vehicle powertrain, the gearbox being connected to and configured to brake a first shaft of thegearbox is provided. The method is performed by a control device, and comprises the steps of: a) when a rotational speed of the first shaft is within a predetermined rotational speedrange for diagnosing performance of the transmission brake, engaging a preselectedsystem adding inertia to the first shaft, if not already engaged; b) braking the first shaft by said transmission brake when said preselected system isengaged, and detecting the deceleration of the first shaft during said braking; and c) determining the performance of the transmission brake by comparing the detecteddeceleration of the first shaft with one or more predetermined threshold values for the deceleration of the first shaft. ln view of the fact that braking is performed while the preselected system adding inertia to the firstshaft is engaged, the first shaft will experience additional inertia. This reduces the decelerationperformance of the first shaft, compared to if braking is performed on the first shaft without the engaged preselected system. This in turn enables measuring the rotational speed of the first shaft and thus the deceleration by means of conventional sensors which are normally already present inthe gearbox. Thereby, the deceleration of the first shaft can be more accurately determined, andcompared with one or more expected values of the deceleration of the first shaft for the purpose ofdetermining the performance of the transmission brake. Moreover, this can be achieved without having to add any additional components to the gearbox per se.

The method may further comprise determining that the operating state of the vehicle is suitable fordiagnosing the transmission brake. The vehicle may be operated in different operating states.Different operating states may be characterised by e.g. the speed with which the vehicle is travelling,standing still, the weight of load the vehicle is carrying just to mention some non-limiting examples.Different operating states may be more or less suitable for diagnosing the transmission brake as willbe explained in more detail below. Thus, by determining that the operating state of the vehicle issuitable for diagnosing the transmission brake, the risk of the method causing any unwanted disruption of the operation of the vehicle may be minimised.

The step of determining that the operating state of the vehicle is suitable for diagnosing thetransmission brake may for example comprise determining that the traveling speed of the vehicle iswithin an acceptable traveling speed range and that a delay in gear shifting is acceptable forcontinued operation of the vehicle. Thereby, it may be ensured that a delay in gear shifting whichmay be caused by performing the method of diagnosing the transmission brake would not cause anydetrimental disruption of the operation of the vehicle. This is particularly advantageous in case themethod for diagnosing the transmission brake is to be performed when the vehicle is travelling on a road.

The step of braking the first shaft by the transmission brake when said preselected system is engagedmay comprise braking to a preselected rotational speed of the first shaft. This has the advantage ofease of control of the braking step. Alternatively, the step of braking the first shaft by thetransmission brake when said preselected system is engaged may comprise braking the first shaft with a preselected rotational speed interval of the first shaft, if desired.

The step of engaging a preselected system adding inertia to the first shaft, if not already engaged,may comprise engaging a preselected gear. Thereby, the constituent components of the gearbox perse may be utilised to provide the additional inertia to the first shaft. Optionally, the method mayfurther comprise a step of disengaging any gear connecting the first shaft to another shaft of the gearbox, if such a gear is engaged, before engaging the preselected gear. Thereby, it may be ensured that only the intended preselected system adds inertia to the first shaft during braking of the firstshaft.

According to one aspect, the first shaft may be a lay shaft of the gearbox and the transmission brakemay thus be a lay shaft transmission brake. ln such a case, engaging the preselected system (if notalready engaged) adding inertia to the first shaft, i.e. the lay shaft, may comprise engaging a splitgear of the gearbox, thereby adding inertia of the input shaft of the gearbox to the lay shaft.Optionally, such an engagement of the split gear may further add the inertia of a c|utch disc to the lay shaft depending on the configuration of the powertrain.

According to a second aspect, the first shaft may be an input shaft of the gearbox and thetransmission brake may thus be an input shaft transmission brake. ln such a case, engaging thepreselected system (if not already engaged) adding inertia to the first shaft, i.e. the input shaft, maycomprise engaging a gear, which connects the input shaft to a lay shaft, thereby adding inertia of the lay shaft to the input shaft.

According to a third aspect, the first shaft may be a main shaft of the gearbox and the transmissionbrake may thus be a main shaft transmission brake. ln such a case, engaging the preselected system(if not already engaged) adding inertia to the first shaft, i.e. the main shaft, may comprise engaging agear, which connects the main shaft to a lay shaft, thereby adding inertia of the lay shaft to the mainshaft. Optionally, engaging the preselected system adding inertia to the first shaft may according tothe third aspect further comprise engaging a gear between the lay shaft and an input shaft of the gearbox. Thereby, also the inertia of the input shaft of the gearbox may be added to the main shaft.

The vehicle powertrain may, according to a further aspect, comprise dual c|utch device. ln such acase, engaging the preselected system adding inertia to the first shaft may comprise utilising one of the clutches of the dual c|utch device so as to add inertia of said one c|utch to the first shaft.

The vehicle powertrain may, according to yet another aspect, comprise a power take-off. ln such acase, the pre-selected system adding inertia to the first shaft may comprise an auxiliary arrangementconnectable to the first shaft via the power take-off. This could for example be utilised whenperforming the method during service or inspection of the vehicle. This also, for example, has theadvantage of providing a higher flexibility in selection of inertia to be added to the first shaft sincethe inertia added is not limited to the available systems for adding inertia to the first shaft present in the powertrain of the vehicle per se.

The present disclosure also relates to a control device configured to perform the above describedmethod. The control device is configured to diagnose a transmission brake of a gearbox of a vehiclepowertrain, the transmission brake being connected to and configured to brake a first shaft of thegearbox. The control device is configured to: i. engaging a preselected system adding inertia to the first shaft, if not alreadyengaged, when a rotational speed of the first shaft is within a predeterminedrotational speed range for diagnosing performance of the transmission brake; ii. when the preselected system adding inertia to the first shaft is engaged, brakethe first shaft by said transmission brake and detect the deceleration of the firstshaft during said braking; and iii. determine the performance of the transmission brake by comparing thedetected deceleration of the first shaft with one or more predetermined threshold values for the deceleration of the first shaft.

The control device may be a control device of the vehicle, such as a control device of the vehiclepowertrain, or may be a remote control device not being part of the powertrain per se but connectable thereto for diagnosing the transmission brake.

The control device may further be configured to determine that the operating state of the vehicle issuitable for diagnosing the transmission brake. Thereby, the control device can determine thatperforming a method for diagnosing the transmission brake will not cause any unwanted disruptionof the operation of the vehicle. The control device may for example be configured to determine thatthe operating state of the vehicle is suitable for diagnosing the transmission brake by determiningthat the traveling speed of the vehicle is within an acceptable traveling speed range and that a delay in gear shifting is acceptable for continued operation of the vehicle.

The control device may further be configured to brake the first shaft by means of the transmissionbrake, when said preselected system is engaged, by braking the first shaft to a preselected rotationalspeed of the first shaft, or by braking the first shaft with a preselected rotational speed range of the first shaft.

The control unit may further be configured to engage a preselected first gear, if not already engaged, thereby engaging the preselected system adding inertia to the first shaft. The control unit may further be configured to disengage any gear connecting the first shaft to another shaft of the gearbox before engaging the preselected gear.

Moreover, the present disclosure relates to a vehicle comprising a powertrain, the powertraincomprising a gearbox having a transmission brake. The vehicle may further comprise a control device as described above.

The present disclosure further relates to a computer program, wherein the computer programcomprises program code for causing a control device or a computer connected to the control deviceto perform the method, as disclosed above, for diagnosing a transmission brake of a gearbox of a vehicle powertrain.

The present disclosure also relates to a computer-readable medium comprising instructions, whichwhen executed by a control device or a computer connected to the control device, cause the controldevice or the computer to perform the method, as disclosed above, for diagnosing a transmission brake of a gearbox 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. 3 schematically illustrates a second exemplifying embodiment of a vehicle powertrain; Fig. 4 schematically illustrates a third exemplifying embodiment of a vehicle powertrain; Fig. 5 represents a flowchart schematically illustrating a method for diagnosing a transmissionbrake of a gearbox of a vehicle powertrain in accordance with the present disclosure; Fig. 6 schematically illustrates a device which may constitute, comprise or be a part of a control device according to the present disclosure.

DETAILED DESCRIPTION The invention will be described in more detail below with reference to exemplifying embodimentsand the accompanying drawings. The invention is however not limited to the exemplifyingembodiments discussed and/or shown in the drawings, but may be varied within the scope of theappended 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 for diagnosing a transmission brake of a gearbox of avehicle powertrain by determining the performance of the transmission brake. The method can beperformed during operation of the vehicle, i.e. during travelling of the vehicle. Alternatively, the method may be performed during scheduled service or inspection of the vehicle.

The method for diagnosing a transmission brake of a gearbox of a vehicle powertrain, thetransmission brake being connected to and being configured to brake a first shaft of the gearbox,comprises at least the following steps: a) when a rotational speed of the first shaft is within a predetermined rotational speedrange for diagnosing performance of the transmission brake, engaging a preselectedsystem adding inertia to the first shaft, if not already engaged; b) braking the first shaft by said transmission brake when said preselected system isengaged, and detecting the deceleration of the first shaft during said braking; and c) determining the performance of the transmission brake by comparing the detecteddeceleration of the first shaft with one or more predetermined threshold values for the deceleration of the first shaft.

The method is performed by a control device configured to perform the method.

Diagnosis of a transmission brake associated with a first shaft, i.e. a transmission brake connected toand configured to brake the first shaft, may be performed if the rotational speed of the first shaft,before braking, is within a predetermined rotational speed range of the first shaft. ln case therotational speed of the first shaft is too low, it could be difficult to brake the first shaft to asufficiently lower rotational speed to thereby determine the deceleration with sufficient accuracy.Furthermore, the rotational speed of the first shaft cannot be too high since additional inertia isadded to the first shaft. The added inertia leads to a higher load on the transmission brake duringbraking. lf the rotational speed of the first shaft is too high, the transmission brake may therefore riskbeing overloaded which could lead to damage of the transmission brake. Therefore, the method is performed when a rotational speed of the first shaft is within a predetermined rotational speed range for diagnosing performance of the transmission brake. The upper value of the predeterminedrotational speed range may constitute a threshold value for the rotational speed of the first shaftcorresponding to a rotational speed which is lower than a rotational speed which may risk leading toan overload of the transmission brake when braking taking into consideration the added inertia ofthe preselected system to the first shaft. The predetermined rotational speed range for diagnosingthe performance of the transmission brake is dependent on the inertia added by the preselectedsystem, as well as the inertia of the first shaft per se and the normal performance of the transmissionbrake. However, as a mere example, the rotational speed of the first shaft when the transmission brake is initiated could be 1000 rpm, and the brake work could correspond to 300 rpm to 600 rpm.. ln case the rotational speed of the first shaft is not within the predetermined rotational speed rangefor diagnosing the performance of the transmission brake, the method may further compriseadjusting the rotational speed of the first shaft such that the rotational speed of the first shaft is withthe predetermined rotational speed range for diagnosing the performance of the transmission brake.The method could for example comprise a step of adjusting the speed of the first shaft to a specific predetermined rotational speed of the first shaft for diagnosing the transmission brake.

The rotational speed of the first shaft may, if needed, be adjusted by means of any previously knownprocess for adjusting the speed of a rotational shaft inside a gearbox of a vehicle powertrain. For example, in case the rotational speed of the first shaft need to be increased, this may be achieved byproviding a connection between an engine of the powertrain and the first shaft, and thereafter using the engine to increase the rotational speed of the first shaft to the desired rotational speed thereof.

When the rotational speed of the first shaft is within the predetermined rotational speed range fordiagnosing performance of the transmission brake, the method comprises engaging a preselectedsystem adding inertia to the first shaft, if not already engaged. The preselected system adding inertiato the first shaft may be a system or arrangement of the powertrain, such as a system orarrangement of the gearbox, or may be an auxiliary system not being part of the powertrain per se, as will be described further below.

As mentioned above, the method comprises a step of engaging a preselected system adding inertiato the first shaft, if not already engaged, when the rotational speed of the first shaft is within thepredetermined rotational speed range for diagnosing the performance of the transmission brake. ltshould be noted that in case the rotational speed of the first shaft for example has to be increased to reach the predetermined rotational speed range of the first shaft to perform the diagnosis, and this has been achieved by connecting the first shaft to other constituent components of the gearbox, thepreselected system adding inertia to the first shaft may already be engaged. However, in mostinstances, the first shaft may be disengaged from adjacent shafts of the gearbox before the methodis commenced, and then the preselected system adding inertia to the first shaft is engaged before the transmission brake is activated such as to brake the shaft during the diagnosis.

One example of a case where the preselected system adding inertia to the first shaft may already beengaged, when the rotational speed of the first shaft is within the predetermined rotational speedrange for diagnosing the performance of the transmission brake, could be when the preselectedsystem adding inertia to the first shaft has also been used for adjusting the rotational speed of thefirst shaft to the predetermined rotational speed range. This could for example be the case when themethod is performed during service of the vehicle and an auxiliary system, not being part of thepowertrain per se, is connected to the powertrain via a power take-off of the powertrain and utilisedfor adjusting the rotational speed of the first shaft. Alternatively, the preselected system addinginertia to the first shaft comprise at least one gear connecting the first shaft to a second shaft of thegearbox providing the rotational speed of the second shaft to the first shaft for adjusting the rotational speed of the first shaft.

When the preselected system adding inertia to the first shaft is engaged, i.e. when the first shaftexperiences the additional inertia of the preselected system, the transmission brake is activated so asto brake the first shaft. During said braking, the deceleration of the first shaft is detected. This maybe achieved by using any previously known sensor or sensors adapted for such a purpose. By way ofexample only, gearboxes today generally comprises a number of sensors configured to determine therotational speed of the different shafts of the gearbox in order to determine the rotational speedthereof when effectuating gear changes. Such sensors may also be used to determine the deceleration of the first shaft according to the present method.

Transmission brakes of gearboxes used to today are often operated by an on/off mode duringoperation of the gearbox, such as during a gear change. ln other words, the transmission brakebrakes the corresponding shaft with full braking torque until the corresponding shaft obtains adesired rotational speed after braking. During said braking, the discs of the transmission brake arepressed against each other using the full force obtainable by the pneumatic actuator. ln the methodfor diagnosing the transmission brake according to the present disclosure, the transmission brake may be operated in a corresponding manner so as to mimic a normal braking step with the exemption that the first shaft experiences additional inertia provided by the preselected system asdescribed above. lt should however be noted that the present disclosure is not limited to atransmission brake adapted to be operated in an on/off mode, and the method for diagnosing atransmission brake may be performed on other types of transmission brakes. The transmission brakemay be a transmission brake having a plurality of parallel discs. Alternatively, the transmission brake may be of conical type wherein the discs to be pressed against each other have a conical shape. ln accordance with one alternative of the method, braking of the first shaft may be performed from afirst preselected rotational speed of the first shaft to a second preselected rotational speed of thefirst shaft. ln accordance with another alternative of the method, the first shaft may, irrespective ofthe initial rotational speed of the first shaft (as long as it is within the predetermined rotationalspeed interval for diagnosing the transmission brake), be braked with a selected rotational speedrange. The method may naturally, irrespective of the alternative used, comprise a step of detectingthe rotational speed of the first shaft immediately before, or at start of, braking the first shaft. At this point in time, the preselected system adding inertia to the first shaft is engaged.

When the deceleration of the first shaft has been detected, the detected deceleration of the firstshaft is compared to one or more predetermined threshold values for the deceleration of the firstshaft. For example, a first threshold value for the deceleration of the first shaft may correspond to athreshold value considered to correspond to an immediate need to replace the transmission brake. Asecond threshold value for the deceleration of the first shaft may for example correspond to a valuewhere there is no immediate need for replacement of the transmission brake, but where theperformance of the transmission brake is considered to be degraded and maintenance should beplanned in advance. A third threshold value may correspond to a threshold value where the transmission brake is considered to have an intended minimum acceptable performance.

Thus, by means of the method for diagnosis, the performance of the transmission brake may bedetermined with sufficient accuracy such that it can be determined if the transmission brake or a part thereof should be replaced.

The method could furthermore comprise a step of transmitting information, corresponding to thedetermined performance of the transmission brake, to a preventive replacement system and/or an alert system capable of informing a driver of the vehicle. 11 As mentioned above, the method for diagnosing a transmission brake of a gearbox of a vehiclepowertrain may be performed during operation of the vehicle, as well as during service or inspectionof the vehicle. ln case the method is to be performed during operation of the vehicle, such as whenthe vehicle is traveling on a road, this could be performed at scheduled intervals or in case ofsuspicion of a deterioration of the performance of the transmission brake. A suspicion ofdeterioration of the performance of the transmission brake could for example be determined by acontrol unit associated with the gearbox, detecting a delay in the synchronisation of the shafts of the gearbox.

The method may further comprise a step of determining that the operating state of the vehicle issuitable for diagnosing the transmission brake. Such a step may be performed before the step ofengaging a preselected system adding inertia to the first shaft, if not already engaged, when therotational speed of the first shaft is within a predetermined rotational speed range for diagnosing theperformance of the transmission brake. A vehicle may be operated in different operating states. Anoperating state could for example be an operating state during service of the vehicle and thepowertrain, or a part thereof, is operated in a service mode without the vehicle per se travelling, i.e.the vehicle is at standstill. Other examples of operating states of the vehicle include when the vehicleis travelling, and are dependent on various factors such as traveling speed of the vehicle, inclinationof road, the weight of load the vehicle is carrying, the operating mode of the vehicle (such as eco-mode, power-mode, off-road mode or the like) etc.. ln such a case, the step of determining that theoperating state of the vehicle is suitable for diagnosing the transmission brake may comprisedetermining that the traveling speed of the vehicle is within an acceptable traveling speed range andthat a delay in gear shifting is acceptable for continued operation of the vehicle. Generally, thetraveling speed of the vehicle may be within an acceptable traveling speed range if the loss intraveling speed, caused by the method for diagnosis, would be 5 % or less of the traveling speedwhen the method is initiated.. Furthermore, since the method for diagnosing the transmission brakemay, depending on the configuration of the gearbox and the gear changing strategy, may cause adelay in gear shifting, the method should be performed when the vehicle is in an operating statewhere such a delay in gear shifting is not detrimental for the continued travel of the vehicle. ln otherwords, the method may be unsuitable to perform for example in case of an uphill climb of the vehicle where a delay in a gear shift may cause a considerable loss of travel speed of the vehicle.

Performance of the transmission brake may be insufficient as a result of degradation of the discs ofthe transmission brake, and/or loss in force provided by a pneumatic actuator. ln case the performance of the transmission brake has been determined to be insufficient, it may be possible to 12 determine if the inferior performance is caused by the discs or by the pneumatic actuator. This canbe made by temporarily replacing the normal pneumatic actuator with its air supply system with atemporary pneumatic actuator with an associated air supply system and thereafter repeating themethod for diagnosing the transmission brake. Such a procedure may be performed during service orinspection of the vehicle. lf the performance of the transmission brake is not sufficient afterrepeating the method for diagnosing the transmission brake, it can be determined that thedegradation of the discs of the transmission brake is the cause for the inferior performance of the transmission brake.

The prese|ected system adding inertia to the first shaft, provides a prese|ected inertia to the firstshaft. Thus, the transmission brake is experiencing both the inertia of the first shaft and of theprese|ected system during braking of the first shaft. Engaging the prese|ected system adding inertiato the first shaft may comprise engaging a prese|ected gear. This means that the first shaft isconnected to a second shaft of the gearbox via the prese|ected gear. Thereby, the inertia of thesecond shaft is added to the first shaft. ln the case of engaging a prese|ected gear so as to add inertiato the first shaft, the method may, before engaging the prese|ected gear, disengaging any gearconnecting the first shaft to another shaft of the gearbox. This could for example be the case wherethe rotational speed of the first shaft has been adjusted by engaging a first gear, different from theprese|ected gear, so as to enable increasing or decreasing the rotational speed of the first shaft to the predetermined rotational speed range for diagnosing performance of the transmission brake.

The prese|ected system may alternatively, or in addition, comprise a dual clutch device. ln such acase, a clutch of the dual clutch device may be engaged so as to add inertia of at least a second shaftof the gearbox to the first shaft. Alternatively, the prese|ected system adding inertia to the first shaftmay be an auxiliary system, not being part of the powertrain per se, engaged so as to connected tothe first shaft via a power take-off of the powertrain. Thereby, the inertia of the auxiliary system isadded to the first shaft. The use of such an auxiliary system may for example be the case during service or inspection of the vehicle.

Figure 1 schematically illustrates a side view of an example of a vehicle 1. The vehicle 1 comprises apowertrain 3 comprising an internal combustion engine 2 and a gearbox 4. A clutch (not shown) maybe 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. 13 The vehicle 1 may be, but is not limited to, a heavy vehicle, e.g. a truck or a bus. Furthermore, thevehicle 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 apowertrain 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. Thegearbox 4 comprises an input shaft 10 connected to the clutch 9 and an output shaft 6 connected tothe driving wheels 5. The gearbox 4 further comprises a first gearbox unit 4A and a second gearboxunit 4B arranged downstream of the first gearbox unit 4A. The second gearbox unit 4B is connectableto the first gearbox unit 4A. The gearbox 4 may optionally further comprise a third gearbox unit 4Cconnectable to the second gearbox unit 4B and the output shaft 6. The first gearbox unit 4A mayconstitute a split gearbox unit. The second gearbox unit 4B may constitute a conventional maingearbox that can be set to a number of different forward gear ratios and optionally one or more reverse gear ratios. The third gearbox unit 4C may constitute a range gearbox.

The second gearbox unit 4B comprises a lay shaft 20 with gear wheels 12B, 13B, 14B, 15B that arerotatably fixed to the lay shaft 20. For example, gear wheel 12B may represent the first gear, gearwheel 13B may represent the second gear, and gear wheel 14B may represent the third gear. Thesecond gearbox 4B also comprises a main shaft 30 with corresponding gear wheels 12A, 13A, 14Awhich rotate freely in relation to the main shaft 30, but which can be selectively locked for rotationwith the main shaft 30 in order to engage a gear. When the gear wheels 12A, 13A, 14A rotate freelyin relation to the main shaft 30, the second gearbox unit 4B is in neutral. 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, arrangedto rotate with the main shaft 30, to a position where the gear wheel 12A is engaged, i.e. to the left inthe figure. The gear wheel 12A will thereby rotate with the main shaft 30, and the lay shaft 20 willthereby be connected to the main shaft 30 via gear wheel 12B. Each pair of gear wheels on the layshaft 20 and main shaft 30 represents a gear ratio. The second gear in the second gearbox unit 4Bmay be engaged by disengaging the first sleeve 16 from the gear wheel 12A and instead moving asecond 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, thethird gear in the second gearbox unit 4B may be engaged by maneuvering the second sleeve 17 tothe 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 14 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, isrotatably fixed to the lay shaft 20. The first gearbox unit 4A comprises a corresponding gear wheel15A rotating freely in relation to the input shaft 10, but which may be selectively locked for rotationwith the input shaft 10 through a split sleeve 18. When the split sleeve 18 locks the gear wheel 15Ain the input shaft 10, torque can be transferred to the lay shaft 20 via the corresponding gear wheel15B on the lay shaft 20. The split sleeve 18 can further be used to connect the input shaft 10 to thegear wheel 14A of the second gearbox unit 4B directly. This way, depending on whether the gearwheel 14A on the main shaft 30 is rotating freely in relation to the main shaft 30 or if it is locked onthe main shaft 30, torque can be transferred to the lay shaft 20 via the corresponding gear wheel 14Bon 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 differentsplit gear ratios for each gear of the second gearbox unit 4B. The first gearbox unit 4A may thus becontrolled to engage a high-split gear or a low-split gear. For example, engaging the low-split gearmay comprise to connect the input shaft 10 with the low gear wheel 14A on the main shaft 30 bymeans of the split sleeve 18. When e.g. the first gear is engaged in the second gearbox unit 4B, thesplit sleeve 18 may be arranged to engage gear wheel 14A. This way, the input shaft 10 is directlyconnected to gear wheel 14B, which via gear 14B establishes a first gear ratio between the inputshaft 10 and the lay shaft 20. The gear wheel 14A, however, is not locked to the main shaft 20, butthe lay shaft 20 may be connected to the main shaft 20 through gear wheel pair 12A/12B. To engagethe second gear, gear wheel pair 15A/15B is instead engaged, resulting in a second gear ratiobetween the input shaft and the lay shaft 20. The gear wheel 12A is still engaged by the first mainsleeve 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 beingconnected to and configured to brake a corresponding shaft of the gearbox. ln Figure 2, an inputshaft transmission brake 11, a lay shaft transmission brake 21 and a main shaft transmission brake 31are shown. The input shaft 10 is provided with the input shaft transmission brake 11 for control of the rotational speed of the input shaft 10. Correspondingly, lay shaft 20 is provided with a lay shaft transmission brake 21 for control of the rotational speed of the lay shaft, and the main shaft 30 is provided with a main shaft transmission brake for control of the rotational speed of the main shaft.

The gearbox 4 need not necessarily comprise the three transmission brakes 11, 21, 31 shown, butmay alternatively comprise only one of the three illustrated transmission brakes, two of theillustrated transmission brakes or even more transmission brakes than illustrated. For example, the gearbox may also comprise a transmission brake associated with the third gearbox unit 4C.

Each of the transmission brakes 11, 21, 31 may for example be pneumatically controlled. Thetransmission brakes may for example constitute a part of a synchronization arrangement. Thepurpose of a synchronization arrangement is to synchronize the rotational speeds of the shafts foreffectuating a gear change. ln some configurations, synchronization may additionally be performed by adjusting the rotational speed of the outgoing shaft of the combustion engine.

The powertrain 3 may furthermore comprise a control device 100. The control device 100 may beconfigured to control the gearbox 4 or at least a part thereof. The control unit may comprise one ormore control units 70. ln Figure 2, only one control unit 70 is illustrated. The control device 100 mayfurther comprise a computer 72 connected to the control unit 70. The control unit(s) 70 and thecomputer 72 may each comprise a memory M and/or a computer program P which will be describedin more detail below. The control device may be connected to one or more constituent componentsof the powertrain 3 via connections 70A. For ease of illustration, the connections 70A of the controldevice 100 have not been fully illustrated in figure 2. The connections 70A may be physicalconnections or non-physical connections, as will be further described below. A control unit 70 of thecontrol device 100 may be connected to any part of the powertrain, such as the combustion engine2, 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 separatecontrol unit connected to the other control units of the control device directly or via a commoncontrol unit. The control device 100 may, if desired, be configured to control the whole powertrain 3 of the vehicle 1.

The method for diagnosing a transmission brake of a gearbox of a vehicle powertrain may be performed on any one of the transmission brakes 11, 21, 31 illustrated in figure 2. ln accordance with one exemplifying embodiment of the method, the first shaft constitutes the lay shaft 20 and the transmission brake to be diagnosed is thus the lay shaft transmission brake 21. ln 16 such a case, a preselected system adding inertia to the first shaft, i.e. the lay shaft 20, may beengaged (if not already engaged) by engaging a split gear of the gearbox 4 by means of the splits|eeve 18. Thereby, the inertia of the input shaft 10 of the gearbox 4 is added to the lay shaft 20.Optionally, the inertia of a disc of the clutch 9 may also be added to the first shaft by engaging the split gear. ln accordance with another exemplifying embodiment of the method, the first shaft constitutes theinput shaft 10 of the gearbox 4 and the transmission brake to be diagnosed thus constitutes the inputshaft transmission brake 11. ln such a case, a preselected system adding inertia to the first shaft, i.e.the input shaft, may be engaged (if not already engaged) by engaging a gear which connects theinput shaft 10 to the lay shaft 20. Thereby, the inertia of the lay shaft 20 is added to the input shaft10. ln accordance with yet another exemplifying embodiment, the first shaft constitutes the main shaft30 of the gearbox 4 and the transmission brake to be diagnosed thus constitutes the main shafttransmission brake 31. ln such a case, a preselected system adding inertia to the first shaft, i.e. themain shaft 30, may be engaged by engaging a gear which connects the main shaft 30 to the lay shaft20. Thereby, the inertia of the lay shaft 20 is added to the main shaft 30. Further inertia mayoptionally be added to the main shaft 30 by also engaging a gear between the lay shaft 20 and theinput shaft 10, if desired. Thereby, the inertia of both the lay shaft and the input shaft will be added to the main shaft.

Figure 3 schematically illustrates a second exemplifying embodiment of a vehicle powertrain 3, suchas a powertrain of the vehicle 1 shown in Figure 1. The powertrain 3 comprises the combustionengine 2 and a gearbox 4. The gearbox 4 comprises an output shaft 6 connected to the drivingwheels 5. Furthermore, the gearbox 4 comprises one or more transmission brakes 41 (only oneillustrated in figure 3). Each transmission brake is arranged to brake a corresponding shaft (not shown) of the gearbox 4 to control the rotational speed of the corresponding shaft. ln contrast to the exemplifying embodiment shown in figure 2, the powertrain 3 shown in figure 3comprises a dual clutch device 9'. The dual clutch 9' is arranged between the combustion engine andthe gearbox 4. The dual clutch device 9' comprises a first clutch 9a, connected to a first gear set (notshown) in the gearbox 4, and a second clutch 9b, connected to a second gear set (not shown) in thegearbox 4. The first clutch 9a and the second clutch 9b may be friction clutches. The first clutch 9a is connected to the first gear set through a first input shaft 10a of the gearbox 4, and the second clutch 17 9b is connected to the second gear set though a second input shaft 10b of the gearbox 4. Gearshifting may be performed by controlling which clutch 9a, 9b to be engaged. ln this way, shifting of gears may be performed without torque interruption on the driving wheels.

The powertrain 3 illustrated in figure 3 may further comprise a control device 100 configured tocontrol at least the gearbox 4 and the dual clutch 9'. The control device may be a control device as described above with regard to the exemplifying embodiment of figure 2.

The method of diagnosing a transmission brake, such as the transmission brake 41 illustrated infigure 3, comprises engaging a preselected system (if not already engaged) adding inertia to a shaftassociated with the transmission brake to be diagnosed as previously disclosed. The preselectedsystem adding inertia to the shaft associated with the transmission brake may in case of theexemplifying embodiment illustrated in figure 3 be engaged by means of one of the clutches 9a, 9b,of the dual clutch device 9'. By way of example, in case the first shaft (which is associated with thetransmission brake to be diagnosed) belongs to a transmission path through the gearbox associatedwith the first clutch 9a, the inertia of the second clutch 9b may be added to the first shaft by engaging a gear connecting the first shaft with the second clutch 9b.

Figure 4 schematically illustrates a third exemplifying embodiment of a vehicle powertrain 3, such asa vehicle powertrain of the vehicle shown in figure 1. The powertrain 3 comprises the combustionengine 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 6connected to the driving wheels 5. The gearbox 4 may comprise a plurality of gearbox units, such asdisclosed above with regard to the exemplifying embodiment illustrated in figure 2. The gearbox 4may further comprise one or more transmission brakes, in figure 4 illustrated as a input shafttransmission brake 11, a lay shaft transmission brake 21 and a main shaft transmission brake 31.Each transmission brake is associated with a corresponding shaft and configured to brake said corresponding shaft in order to control the rotational speed thereof.

The powertrain 3 shown in figure 4 further comprises a power take-off 40. A power take-off constitutes a connection point where an auxiliary system or arrangement (not shown), not being partof the powertrain per se, may selectively be coupled to the powertrain 3 of a vehicle. The power-takeoff 40 may be adapted to transmit rotation from a shaft of the gearbox 4 to the auxiliary system. Thepower take-off 40 may have any configuration previously known, and will therefore not be described in more detail herein. Merely as an example, the power take-off may comprise a splined shaft. 18 As also shown in figure 4, the powertrain may further comprise a control device 100. The controldevice 100 can be a control device as described above with regard to the exemplifying embodimentshown in figure 2. The control device 100 may for example be connected to the gearbox 4. While notshown in figure 4, the control device may further be connected to other constituent parts of the powertrain, such as the combustion engine 2 and/or the clutch 9.

The method of diagnosing a transmission brake of the gearbox 4, such as one of the transmissionbrakes 11, 21, 31 illustrated in figure 4, may comprise engaging an auxiliary arrangement (not shown)to add inertia to a shaft associated with the transmission brake to be diagnosed. The auxiliaryarrangement is engaged by connecting the auxiliary arrangement to the first shaft via the power ta ke-off 40.

Figure 5 represents a flowchart schematically illustrating a method, performed by a control device,for diagnosing a transmission brake of a gearbox of a vehicle powertrain, wherein the transmissionbrake is associated with a first shaft of the gearbox. The method comprises a first step, S100, ofengaging a preselected system adding inertia to the first shaft, if not already engaged, when therotational speed of the first shaft is within a predetermined rotational speed range for diagnosing theperformance of the transmission brake. Thereafter, the method comprises a second step, S200, ofbraking the first shaft, using the transmission brake, when the preselected system is engaged anddetecting the deceleration of the first shaft during said braking. The method further comprises athird step, S300, of determining the performance of the transmission brake by comparing thedetected deceleration of the first shaft with one or more predetermined threshold values for the deceleration of the first shaft.

The present disclosure also relates to a control device configured to diagnose a transmission brake ofa gearbox of a vehicle powertrain, the transmission brake being connected to and configured tobrake a first shaft of the gearbox. The control device is at least configured to:i. when the rotational speed of the first shaft is within a predetermined rotationalspeed range for diagnosing performance of the transmission brake, engaging apreselected system adding inertia to the first shaft, if not already engaged;ii. when the preselected system adding inertia to the first shaft is engaged, brakethe first shaft by said transmission brake and detect the deceleration of the first shaft during said braking; and 19 iii. determine the performance of the transmission brake by comparing thedetected deceleration of the first shaft with one or more predetermined threshold values for the deceleration of the first shaft.

The control device may further be configured to determine that the operating state of the vehicle issuitable for diagnosing the transmission brake. For example, the control device may be configured todetermine that the operating state of the vehicle is an operating state wherein the vehicle is atstandstill, such as during a service mode, but at least a part of the powertrain is operable. The controldevice may further be configured to, in case the vehicle is traveling, determining the operating stateof the vehicle by determining that the traveling speed of the vehicle is within an acceptable travelingspeed range and that a delay in gear shifting is acceptable for continued operation of the vehicle. Adelay in gear shifting may be acceptable for continued operation of the vehicle in case such a delay ingear shifting does not cause the vehicle to lose too much in traveling speed. By way of example only, a loss of up to 5% of the traveling speed of the vehicle may be acceptable.

The control device may further be configured to perform any of the steps described above with regard to the method for diagnosing a transmission brake of a gearbox of a vehicle powertrain.

The control device may be a control device of the vehicle powertrain, such as the control device 100described above. Alternatively, the control device may be a remote control device connectable to thevehicle powertrain when diagnosis of the transmission brake is to be performed. According to yet analternative, the control device may comprise at least one control unit of the vehicle powertrain andat least one remote control unit, not being part of the powertrain per se, but being connectable to the powertrain when diagnosis of the transmission brake is to be performed.

The present disclosure further relates to a vehicle, such as the vehicle shown in figure 1 above. Thevehicle has a vehicle powertrain comprising a gearbox. The gearbox comprises a transmission brakeassociated with a first shaft of the gearbox, i.e. the transmission brake is connected to and configured to brake the first shaft to control the rotational speed thereof for example during a gearchange. The vehicle may further comprise the control device configured to diagnose a transmission brake of the gearbox as described above.

Figure 6 schematically illustrates an exemplifying embodiment of a device 500. The control device100 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 physicalconnection 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/writememory 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 device 500 further comprises a bus controller, a serial communication port, I/O means, an A/Dconverter, a time and date input and transfer unit, an event counter and an interruption controller (not depicted). The non-volatile 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).

There is provided a computer program P which comprises routines for diagnosing a transmissionbrake of a gearbox of a vehicle powertrain, the transmission brake being connected to andconfigured to brake a first shaft of the gearbox. The computer program P comprises routinesengaging a preselected system adding inertia to the first shaft, if not already engaged, when arotational speed of the first shaft is within a predetermined rotational speed range for diagnosingperformance of the transmission brake. The computer program P comprises routines braking the firstshaft by means of the transmission brake when said preselected system is engaged, and detectingthe deceleration of the first shaft during said braking. The computer program further comprisesroutines for determining the performance of the transmission brake by comparing the detecteddeceleration of the first shaft with one or more predetermined threshold values for the deceleration of the first shaft.

The program P may be stored in an executable form or in a compressed form in a memory 560and/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 thedata 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. 21 The data processing device 510 can communicate with a data port 599 via a data bus 515. The non-vo|ati|e memory 520 is intended for communication with the data processing unit 510 via a data bus512. The separate memory 560 is intended to communicate with the data processing unit 510 via adata bus 511. The read/write memory 550 is adapted to communicating with the data processing unit 510 via a data bus 514.

When data are received on the data port 599, they are stored temporari|y in the second memoryelement 540. When input data received have been temporari|y 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 dataprocessing 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. 22 Method for diagnosing a transmission brake (11, 21, 31, 41) of a gearbox (4) of a vehiclepowertrain (3), the transmission brake (11, 21, 31, 41) being connected to and configured tobrake a first shaft (10, 20, 30) of the gearbox, the method being performed by a controldevice (100),the method comprising the steps of:a) when a rotationa| speed of the first shaft (10, 20, 30) is within a predeterminedrotationa| speed range for diagnosing performance of the transmission brake (11, 21,31, 41), engaging a prese|ected system adding inertia to the first shaft (10, 20, 30), ifnot already engaged, (S100);b) braking the first shaft (10, 20, 30) by said transmission brake (11, 21, 31, 41) whensaid prese|ected system is engaged, and detecting the deceleration of the first shaft(10, 20, 30) during said braking (S200); andc) determining the performance of the transmission brake (11, 21, 31, 41) bycomparing the detected deceleration of the first shaft (10, 20, 30) with one or morepredetermined threshold values for the deceleration of the first shaft (10, 20, 30) (S300). Method according to claim 1, further comprising determining that the operating state of thevehicle (1) is suitable for diagnosing the transmission brake (11, 21, 31, 41); preferablywherein determining that the operating state of the vehicle (1) is suitable for diagnosing thetransmission brake (11, 21, 31, 41) comprises determining that the traveling speed of thevehicle (1) is within an acceptable traveling speed range and that a delay in gear shifting is acceptable for continued operation of the vehicle (1). Method according to any one of claims 1 or 2, wherein the step of braking the first shaft (10,20, 30) by the transmission brake (11, 21, 31, 41) when said prese|ected system is engagedcomprises braking to a prese|ected rotationa| speed of the first shaft (10, 20, 30), or braking the first shaft (10, 20, 30) with a prese|ected rotationa| speed interval of the first shaft. Method according to any one of the preceding claims, wherein the step of engaging aprese|ected system adding inertia to the first shaft (10, 20, 30), if not already engaged, comprises engaging a prese|ected gear. 10. 11. 23 Method according to claim 4, further comprising disengaging any gear connecting the first shaft (10, 20, 30) to another shaft of the gearbox (4) before engaging the preselected gear. The method according to any one of the preceding claims, wherein the first shaft is a layshaft (20) and the transmission brake is a lay shaft transmission brake (21), and whereinengaging the preselected system adding inertia to the first shaft (20) comprises engaging asplit gear of the gearbox (4), thereby adding inertia of the input shaft (10) of the gearbox (4), and optionally inertia of a clutch disc, to the lay shaft (20). The method according to any one of claim 1 to 5, wherein the first shaft is an input shaft (10)of the gearbox (4) and the transmission brake is an input shaft transmission brake (11), andwherein engaging the preselected system adding inertia to the first shaft (10) comprisesengaging a gear, which connects the input shaft (10) to a lay shaft (20), thereby adding inertia of the lay shaft (20) to the input shaft (10). The method according to any one of claims 1 to 5, wherein the first shaft is a main shaft (30)of the gearbox and the transmission brake is a main shaft transmission brake (31), andwherein engaging the preselected system adding inertia to the first shaft comprises engaginga gear, which connects the main shaft (30) to a lay shaft (20), thereby adding inertia of thelay shaft (20) to the main shaft (30). The method according to claim 8, wherein engaging the preselected system adding inertia tothe first shaft (30) further comprises engaging a gear between the lay shaft (20) and an inputshaft (10) of the gearbox. Method according to any one of claims 1-3, wherein the vehicle powertrain (3) comprises adual clutch device (9') and wherein engaging the preselected system adding inertia to thefirst shaft comprises uti|ising a clutch (9a, 9b) of the dual clutch device (9') so as to add inertia of said clutch to the first shaft. Method according to any one of claims 1-3, wherein the vehicle powertrain (3) comprises apower take-off (40) and wherein the pre-selected system adding inertia to the first shaft comprises an auxiliary arrangement connectable to the first shaft via the power take-off (40). 12. 13. 14. 15. 16. 24 A control device (100) configured to diagnose a transmission brake (11, 21, 31, 41) of agearbox (4) of a vehicle powertrain (3), the transmission brake (11, 21, 31, 41) beingconnected to and configured to brake a first shaft (10, 20, 30) of the gearbox (4), the controldevice configured to:i. when a rotational speed of the first shaft (10, 20, 30) is within a predeterminedrotational speed range for diagnosing performance of the transmission brake(11, 21, 31, 41), engaging a preselected system adding inertia to the first shaft(10, 20, 30), if not already engaged;ii. when the preselected system adding inertia to the first shaft (10, 20, 30) isengaged, brake the first shaft (10, 20, 30) by said transmission brake (11, 21, 31,41) and detect the deceleration of the first shaft (10, 20, 30) during said braking;andiii. determine the performance of the transmission brake (11, 21, 31, 41) bycomparing the detected deceleration of the first shaft (10, 20, 30) with one ormore predetermined threshold values for the deceleration of the first shaft (10, zo, so). The control device according to claim 12, further configured to determine that the operatingstate of the vehicle (1) is suitable for diagnosing the transmission brake (11, 21, 31, 41);preferably configured to determine that the operating state of the vehicle (1) is suitable fordiagnosing the transmission brake (11, 21, 31, 41)by determining that the traveling speed ofthe vehicle (1) is within an acceptable traveling speed range and that a delay in gear shifting is acceptable for continued operation of the vehicle (1). A vehicle (1) comprising a powertrain (3) comprising a gearbox (4), and a control device (100) according to any one of claims 12 or 13. A computer program (P), wherein said computer program comprises program code forcausing a control device (100) or a computer connected to the control device (100) to perform the method according to any one of claims 1 to 11. A computer-readable medium comprising instructions, which when executed by a controldevice (100) or a computer connected to the control device (100), cause the control device (100) or the computer to perform the method according to any one of claims 1 to 11.