SE540228C2

SE540228C2 - System and method for detecting malfunction related to a gearbox arrangement

Info

Publication number: SE540228C2
Application number: SE1550062A
Authority: SE
Inventors: Udd Jonas; Kjell Anders
Original assignee: Scania Cv Ab
Priority date: 2015-01-23
Filing date: 2015-01-23
Publication date: 2018-05-02
Also published as: SE1550062A1; DE102016000705A1

Abstract

The invention relates to a method for detecting malfunction related to a gearbox arrangement (250) comprising a gearbox shaft (251; 252) attached to an additional shaft (275) fixed to said gearbox shaft (251; 252), a braking means (271) being provided for braking said additional shaft (275) and consequently said gearbox shaft (251; 252). The method comprises the steps of:- continuously determining (s410) a prevailing rotational speed (N) of said gearbox shaft (251; 252);- determining (s420) a gearbox shaft rotational speed function at least after activation of said braking means (271) on the basis of said prevailing rotational speed (N) of said gearbox shaft (251; 252); and- determining (s430) malfunction related to said gearbox arrangement (250) on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function.The invention relates also to a computer programme product comprising program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention relates also to a system for detecting malfunction related to a gearbox arrangement (250) and a vehicle (100; 110) equipped with the system.

Description

System and method for detecting malfunction related to a gearbox arrangement TECHNICAL FIELD The present invention relates to a method for detecting malfunction related to a gearbox arrangement. The invention relates also to a computer program product comprising program code for a computer for implementing a method according to the invention. It relates also to a system for detecting malfunction related to a gearbox arrangement and vehicle equipped with the system.

BACKGROUND Some vehicles of today are arranged with an engine and transmission, which transmission comprises a gearbox arrangement having a main shaft and at least one lay shaft. According to one embodiment an additional shaft is connected to a shaft of said gearbox arrangement. Said additional shaft is hereby arranged to drive a lubricant pump for lubricating said gearbox arrangement. Said lubricant pump is hereby mechanically driven by means of said additional shaft.

Braking means is hereby associated with said additional shaft. The braking means is arranged to reduce rotational speed of said additional shaft and thus also the shaft which it is connected to. Hereby effective gear shifts of said gearbox arrangement are achieved.

During applied braking force at said additional shaft by means of said braking means said shaft can break. This particularly holds true in case a lubricating fluid, e.g. comprising oil, of said lubricant means is relatively cold and thus more viscous. This is naturally highly undesired and may have disastrous consequences. If said additional shaft suffers from a break insufficient lubrication of said gearbox arrangement by means of said pump may cause breakdown of said gearbox arrangement. Further, if said additional shaft suffers from a break, gear shift performance of said gearbox arrangement will be heavily deteriorated.

W02005102766 is related to a drive unit for motor vehicles which includes a sensor for gearbox input torque and a unit for compensating torque loss. A control unit may be designed to emit a signal indicating a defect in an intermediate shaft brake of the gearbox, if a torque characteristic lies outside predefined limits stored in the control unit.

SUMMARY OF THE INVENTION An object of the present invention is to propose a novel and advantageous method for detecting malfunction related to a gearbox arrangement.

Another object of the invention is to propose a novel and advantageous system and a novel and advantageous computer program for detecting malfunction related to a gearbox arrangement.

Yet another object of the invention is to propose a method, a system and a computer program for achieving a robust and reliable detection of a malfunction of a gearbox of a transmission.

Yet another object of the invention is to propose an alternative method, an alternative system and an alternative computer program for detecting malfunction related to a gearbox arrangement.

Some of these objects are achieved with a method for detecting malfunction related to a gearbox arrangement comprising a gearbox shaft attached to an additional shaft fixed to said gearbox shaft, a braking means being provided for braking said additional shaft and consequently said gearbox shaft according to claim 1. Other objects are achieved with a system according to claim 6. Advantageous embodiments are depicted in the dependent claims. Substantially the same advantages of method steps of the innovative method hold true for corresponding means of the innovative system.

According to an aspect of the invention there is provided a method for detecting malfunction related to a gearbox arrangement comprising a gearbox shaft attached to an additional shaft fixed to said gearbox shaft, a braking means being provided for braking said additional shaft and consequently said gearbox shaft. The method comprises the steps of: - continuously determining a prevailing rotational speed of said gearbox shaft; - determining a gearbox shaft rotational speed function at least after activation of said braking means on the basis of said prevailing rotational speed of said gearbox shaft; and - determining malfunction related to said gearbox arrangement on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function. Hereby is a reliable, robust and accurate method for detecting malfunction related to a gearbox arrangement provided - determining a characteristic change of reduction of said prevailing rotational speed of said gearbox shaft during a state of activated braking means as an indication for malfunction of said braking means. Hereby is a reliable, robust and accurate method for determining malfunction of said braking means advantageously provided.

The method may comprise the step of: - determining a characteristic change of reduction of said prevailing rotational speed of said gearbox shaft during a state of activated braking means as an indication for breaking of said additional shaft. Hereby is a reliable, robust and accurate method for determining breaking of said additional shaft advantageously provided.

The method may comprise the step of: - driving a gearbox lubricant pump by means of said additional shaft.

In the method said gearbox shaft may be a main shaft or a lay shaft.

The method may comprise the step of: - activating an indication in case of a determined malfunction of said gearbox arrangement.

According to an aspect of the invention there is provided a system for detecting malfunction related to a gearbox arrangement comprising a gearbox shaft attached to an additional shaft fixed to said gearbox shaft, a braking means being provided for braking said additional shaft and consequently said gearbox shaft. The system comprises: - means for continuously determining a prevailing rotational speed of said gearbox shaft; - means for determining a gearbox shaft rotational speed function at least after activation of said braking means on the basis of said prevailing rotational speed of said gearbox shaft; and - means for determining malfunction related to said gearbox arrangement on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function - means for determining a characteristic change of reduction of said prevailing rotational speed of said gearbox shaft during a state of activated braking means as an indication for malfunction of said braking means.

The system may comprise: - means for determining a characteristic change of reduction of said prevailing rotational speed of said gearbox shaft during a state of activated braking means as an indication for breaking of said additional shaft.

The system may comprise: - a gearbox lubricant pump arranged to be driven by means of said additional shaft.

Said gearbox shaft may be a main shaft or a lay shaft.

The system may comprise: - means for activating an indication in case of a determined malfunction of said gearbox arrangement.

According to an aspect of the invention there is provided a vehicle comprising a system according to what is depicted herein. The vehicle may be anyone from among a truck, bus or passenger car.

According to an aspect of the invention there is provided a computer program for detecting malfunction related to a gearbox arrangement comprising a gearbox shaft attached to an additional shaft fixed to said gearbox shaft, a braking means being provided for braking said additional shaft and consequently said gearbox shaft, wherein said computer program comprises program code for causing an electronic control unit or a computer connected to the electronic control unit to perform the steps according to the invention, when run on said electronic control unit or said computer.

According to an aspect of the invention there is provided a computer program for detecting malfunction related to a gearbox arrangement comprising a gearbox shaft attached to an additional shaft fixed to said gearbox shaft, a braking means being provided for braking said additional shaft and consequently said gearbox shaft, wherein said computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform the steps according to the invention.

According to an aspect of the invention there is provided a computer program for detecting malfunction related to a gearbox arrangement comprising a gearbox shaft attached to an additional shaft fixed to said gearbox shaft, a braking means being provided for braking said additional shaft and consequently said gearbox shaft, wherein said computer program comprises program code stored on a computer-readable medium for causing an electronic control unit or a computer connected to the electronic control unit to perform the steps according to the invention, when run on said electronic control unit or said computer.

According to an aspect of the invention there is provided a computer program product containing a program code stored on a computer-readable medium for performing method steps according to the invention, when said computer program is run on an electronic control unit or a computer connected to the electronic control unit.

According to an aspect of the invention there is provided a computer program product containing a program code stored non-volatile on a computer-readable medium for performing method steps according to the invention, when said computer program is run on an electronic control unit or a computer connected to the electronic control unit.

Further objects, advantages and novel features of the present invention will become apparent to one skilled in the art from the following details, and also by putting the invention into practice. Whereas the invention is described below, it should be noted that it is not confined to the specific details described. One skilled in the art having access to the teachings herein will recognise further applications, modifications and incorporations in other fields, which are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS For fuller understanding of the present invention and its further objects and advantages, the detailed description set out below should be read in conjunction with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which: Figure 1 schematically illustrates a vehicle according to an embodiment of the invention; Figure 2a schematically illustrates a system for the vehicle depicted in Figure 1; Figure 2b schematically illustrates a gearbox arrangement of the vehicle depicted in Figure 1, according to an embodiment of the invention; Figure 3 schematically illustrates a diagram wherein a rotational speed is given as a function of time; Figure 4a is a schematic flowchart of a method according to an embodiment of the invention; Figure 4b is a more detailed schematic flowchart of a method according to an embodiment of the invention; and Figure 5 schematically illustrates a computer according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS With reference to Figure 1 there is illustrated a side view of a vehicle 100. The exemplified vehicle 100 comprises a tractor unit 110 and a trailer 112. The vehicle may be a heavy vehicle, e.g. a truck or a bus. It may alternatively be a passenger car.

Even though the vehicle herein is exemplified by a lorry it should be noted that the present invention is applicable to various suitable vehicles, such as e.g. forest machines, mining vehicles, heavy duty vehicles, construction vehicles, rescue vehicles, etc. The vehicle may have any suitable configuration, e.g. comprising one or more units, including at least one trailer.

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

Figure 2a schematically illustrates a system 299 of the vehicle 100. The system 299 is situated in the tractor unit 110. It should be noted that the innovative method is applicable for various power train configurations, e.g. a hybrid system.

The system 299 comprises a combustion engine 230 which has an output shaft 235 connected to a clutch arrangement 240. The clutch arrangement may be any suitable clutch arrangement. It may comprise a sliding clutch with pressure discs and plates. The clutch arrangement 240 is connected to an input shaft 245 of a gearbox arrangement 250. The gearbox arrangement 250 has an output shaft 255 connected to a differential unit (not illustrated) for conveying torque/power to a number of powered wheels 260a and 260b via respective drive shafts.

In case the system 299 comprises a hybrid system (not illustrated) this further comprises an electrical machine configuration comprising an electrical machine associated with the gearbox input shaft 245. The electrical machine is connected electrically to an energy storage. The energy storage may be of any suitable kind. It may in one example be a battery of any suitable kind, e.g. a lithium ion battery. The battery may alternatively be for example a NiMH battery. In another example the energy storage may be an electrochemical energy storage, e.g. an electrochemical capacitor known as SuperCap. Said energy storage is herein exemplified with a battery of conventional kind for hybrid systems.

In one embodiment, the electrical machine is adapted to being supplied with power by said energy storage and thereby serving as a motor in the vehicle's power train to impart driving torque/power to the gearbox input shaft 245. In one embodiment the electrical machine is adapted to serving as a generator of the electrical machine configuration and thereby charging the energy storage during braking of the vehicle 100. Said electrical machine may typically run alternately as motor and generator.

According to this example the battery is connected electrically to an electrical rectifier by a cable. The rectifier is adapted to converting DC voltage supplied from the battery via the cable to a desired suitable three-phase voltage. In alternative embodiments of the invention, electrical machines herein described may be run with any desired number of phases, e.g. one phase or two phases. The rectifier is adapted to supplying said three-phase voltage to the electrical machine via a cable to power and run the electrical machine. Said DC voltage may amount to several hundred volts, e.g. 400 volts or 600 volts.

Said electrical machine configuration comprises said electrical machine, rectifier, battery and necessary connections between them.

The rectifier is arranged accordingly so that during braking of the vehicle it converts to DC voltage a three-phase AC voltage generated from the electrical machine and supplied to the rectifier. The rectifier is arranged to supply said DC voltage to the battery via the cable to charge the battery.

A first control unit 200 is arranged for communication with the engine 230 via a link L230. The first control unit 200 is adapted to controlling the operation of the engine according to stored routines. It is for example adapted to guiding an engine's prevailing speed (or output shaft torque/power) towards a requested speed (or requested output shaft torque/power).

The first control unit 200 is arranged for communication with the clutch arrangement 240 via a link L240. The first control unit 200 is adapted to controlling the operation of the clutch arrangement 240 according to stored routines. It is for example adapted to opening the clutch 240, slipping the clutch 240 and closing the clutch 240 according to said stored routines.

Said clutch arrangement 240 is associated with an actuator means 270 for affecting the position of the clutch arrangement 240, e.g. so as to close and open said clutch arrangement for adequate operation of the transmission of said vehicle 100. Said actuator means 270 may be any suitable actuator means for said clutch arrangement 240. Said first control unit 200 is arranged for communication with said actuator means 270 by means of said link L240. Said actuator means may be a separate unit or integrally formed with the clutch arrangement 240.

Referring to the example of said parallel hybrid system the first control unit 200 is arranged for communication with the electrical machine via a link. The first control unit 200 is adapted to controlling the operation of the electrical machine according to stored routines.

The first control unit 200 is arranged for communication with the gearbox arrangement 250 via a link L250. The first control unit 200 is adapted to controlling the operation of the gearbox arrangement 250 according to stored routines. It is for example adapted to causing different gear steps in the gearbox 250, including neutral position, according to said stored routines. The gearbox 250 may be a so-called automatic manual gearbox (AMT).

A braking means 271 is arranged at the gearbox arrangement 250. Said first control unit 200 is arranged to control operation of said braking means 271 via said link L250. Said braking means may comprise a friction brake device. Said braking means 271 is depicted in greater detail with reference to Figure 2b below.

A gearbox lubricant pump 272 is arranged at the gearbox arrangement 250. Said gearbox lubricant pump 272 may be an oil pump which is mechanically operated by means of a shaft of said gearbox arrangement 250. Said gearbox lubricant pump 272 is depicted in greater detail with reference to Figure 2b below.

It should be noted that certain of the above functions may be performed by the first control unit 200 and certain of them by the second control unit 210.

The first control unit 200 is arranged for communication with a rotational speed sensor 281 via a link L281. Said rotational speed sensor 281 is provided to continuously detect a prevailing rotational speed N of a shaft of the gearbox arrangement 250 being associated with said braking means 271. The rotational speed sensor 281 is adapted to continuously sending signals 5281 which contain information about a prevailing rotational speed N of the shaft to the first control unit 200 via the link L281. Said detected rotational speed N may be used as a parameter for determining malfunction related to said gearbox arrangement 250 on the basis of appearance of certain characteristic changes of a gearbox shaft rotational speed function according to one aspect of the invention.

A second control unit 210 is arranged for communication with the first control unit 200 via a link L210. The second control unit 210 may be detachably connected to the first control unit 200. The second control unit 210 may be a control unit external to the vehicle 100. The second control unit 210 may be adapted to performing the innovative method steps according to the invention. The second control unit 210 may be used to cross-load software to the first control unit 200, particularly software for applying the innovative method. The second control unit 210 may alternatively be arranged for communication with the first control unit 200 via an internal network in the vehicle. The second control unit 210 may be adapted to performing substantially similar functions to those of the first control unit 200 such as for example determining a gearbox shaft rotational speed function at least after activation of said braking means 271 on the basis of said prevailing rotational speed N of said gearbox arrangement shaft and determining malfunction related to said gearbox arrangement 250 on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function.

Figure 2b schematically illustrates a gearbox arrangement 250 of the vehicle 100. Said gearbox arrangement 250 comprises a main shaft 251 having a number of gear wheels. Said gearbox arrangement 250 comprises a lay shaft 252 having a number of gear wheels. Said gearbox arrangement 250 may be provided with more than one lay shaft. Said gearbox arrangement 250 is arranged to adequately provide a selected gear ratio and transmit torque from said input shaft 245 to said output shaft 255.

An additional shaft 275 is arranged at said lay shaft 252. Said additional shaft 275 may also be denoted extension shaft. Said additional shaft 275 is fixedly secured at said lay shaft 252 and thus provides the same rotational speed N as said lay shaft 252 during operation of said gearbox arrangement 250. The additional shaft 275 has the same centre axis as said lay shaft 252.

Said braking means 271 is arranged for, when applicable, reduce rotational speed N of said additional shaft 275 for effecting gear shifts in said gearbox arrangement 250. Said first control unit 200 is arranged to control operation of said braking means 271 by applying a braking force F to said additional shaft 275. Said braking force F may be applied continuously. According to another example said braking force F is applied to said additional shaft 275 in a non-constant manner, according to any predetermined function.

According to this example a substantially constant braking force F is applied to said additional shaft 275, and thus said lay shaft 252. Said braking force F may alternatively be applied intermittently. According to this example a braking force F may be applied with a certain frequency, whereby said braking force F is applied at a level of zero Newton and a predetermined level, alternately. According to another example any suitable braking force F may be applied. A most suitable braking force application may be performed paying regard to a prevailing configuration of said braking means 271. If the braking means is strong it may be necessary to apply the braking force intermittently so that the total braking force is not too large. If the braking means on the other hand is not so strong it may be possible to apply the braking force continuously without endangering constituent components or the braking process.

A gearbox lubricant pump 272 is arranged at said additional shaft 275. Said lubricant pump 272 is according to an example an oil pump. Said lubricant pump is arranged to provide adequate lubrication of said gearbox arrangement 250 by providing a lubricating means, e.g. oil, during operation. Said lubricating pump 272 is arranged to be mechanically driven by means of said additional shaft 275. Hereby said lubricating pump 272 is affected by a prevailing rotational speed N of said additional shaft 275.

According to one example said braking means 271 and said gearbox lubricant pump 272 are arranged as one integrated unit. According to the example given here said gearbox lubricant pump 272 is arranged between said braking means 271 and said lay shaft 252 at said additional shaft 275. According to an alternative said braking means 271 is arranged between said lubricant pump 272 and said lay shaft 252 at said additional shaft 275.

Hereby is illustrated said rotational speed sensor 281, which is arranged to continuously determine a prevailing rotational speed N of said lay shaft 252. The additional shaft 275 present the same prevailing rotational speed N as said lay shaft 252. According to an example said rotational speed sensor may be arranged at any other shaft of the gearbox arrangement 250, e.g. said main shaft 251, input shaft 245 or output shaft 255, whereby said first control unit 200 is arranged to continuously determine said rotational speed of said lay shaft 252 on the basis of e.g. an engaged gear step of said gearbox arrangement 250.

Even though it is hereby depicted that said additional shaft is attached to said lay shaft 252 it should be understood that the invention is applicable to other configurations of said gearbox arrangement 250. Hereby it is determined a prevailing rotational speed N of the shaft to which said braking means 271 is attached.

According to an example said additional shaft 275 is attached to said main shaft 251. Hereby said braking means 271 is arranged at said additional shaft 275 so as to reduce rotational speed N of said main shaft 251 when applied. Said rotational speed sensor 281 hereby may be arranged to continuously determine a prevailing rotational speed N of said main shaft 251.

Said first control unit 200 is according to an embodiment arranged to continuously determine a prevailing rotational speed N of a gearbox shaft which is connected to the additional shaft 275 being provided with said braking means 271 and optionally said lubricant pump 272. Said gearbox shaft may be the lay shaft 252 or the main shaft 251. Said first control unit 200 is according to an embodiment arranged to continuously determine a prevailing rotational speed N of a gearbox shaft on the basis of said signals S281.

Said first control unit 200 is according to an embodiment arranged to determine a gearbox shaft rotational speed function at least after activation of said braking means 271 on the basis of said prevailing rotational speed N of said gearbox shaft.

Said first control unit 200 is according to an embodiment arranged to control operation of said braking means 271.

Said first control unit 200 is according to an embodiment arranged to determine malfunction related to said gearbox arrangement 250 on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function. Said malfunction may be any of break of said additional shaft, improper or non-existing performance of said brake means 271 and improper or non-existing performance of surrounding equipment of said brake means 271 or lubricant pump 272.

Said first control unit 200 is according to an embodiment arranged to determine a characteristic change of reduction of said prevailing rotational speed of the gearbox shaft being connected to said additional shaft 275 during a state of activated braking means 271 as an indication for breaking of said additional shaft 275.

Said first control unit 200 is according to an embodiment arranged to determine a characteristic change of reduction of said prevailing rotational speed of said gearbox shaft being connected to said additional shaft 275 during a state of activated braking means 271 as an indication for malfunction of said braking means.

Said first control unit 200 is according to an embodiment arranged to present information for an operator of the vehicle 100 by means of a presentation means 290. Said first control unit 200 is arranged for communication with said presentation means via a link L290. Said presentation means may comprise audio visual equipment, e.g. a presentation screen. Said presented information may comprise information about said determined malfunction. Said presented information may comprise instructions to an operator of the vehicle 100, such as "shut down the vehicle immediately", "park the vehicle at your earliest convenience", "service of the vehicle is recommended", "no malfunction of the gearbox arrangement has been detected", etc.

With reference to Figure 3 there is schematically illustrated a diagram presenting a gearbox shaft rotational speed function comprising rotational speed N of a gearbox shaft as a function of time T. The rotational speed N is given in revolutions per minute (rpm) and the time T is given in seconds (s). Said gearbox shaft is attached to said additional shaft 275 having said brake means arranged thereto and optionally said gearbox shaft may be said main shaft 251 or said lay shaft 252. Said rotational speed N may be determined by means of said rotational speed sensor 281 or in any other suitable way, e.g. by means of said first control unit 200.

Initially said braking means 271 is not activated and is thus not actively reducing said rotational speed N of said gearbox shaft. However, due to various reasons, such as e.g. internal friction of said gearbox arrangement 250, said rotational speed N is decreased until a first time point T1. A first time derivative value N1prim of said reduction of rotational speed N may be determined regarding a time period T0-T1 by means of said first control unit 200.

At said first time point T1 said brake means 271 is activated and hereby a braking force F is applied to said additional shaft 275. Hereby said rotational speed N is reduced from a first value N1 at said time point T1 to a second value N2 at a second time point T2. A second time derivative value N2prim of said reduction of rotational speed N may be determined regarding a time period T1-T2 by means of said first control unit 200.

At said second time point T2 a malfunction of said gearbox arrangement occurs. In this case said additional shaft 275 breaks. Hereby said braking force F is no longer actuating said additional shaft 275 and a third time derivative value N3prim of said rotational speed N is provided between said second time point T2 and a third time point T3. Said third time derivative value N3prim of said rotational speed N may be substantially of the same magnitude as said first time derivative value Nlprim of said rotational speed N. An evident change of rate regarding said rotational speed N hereby occurs at said second point of time T2. Hereby an appearance of certain characteristic changes of said gearbox shaft rotational speed function is presented. This appearance of certain characteristic changes comprises a sudden change of time derivative values before and after said break of said additional shaft 275.

Said malfunction of said gearbox arrangement 250 may relate to various reasons. In the example given with reference to Figure 3 it is with relatively high probability detected that a break of said additional shaft has occurred. This because of the certain characteristic of the function at the second time point T2. Since the change of a prevailing time derivative value at said second time point T2 is quite abrupt it is most likely that a break of said additional shaft 275 has occurred.

Other reasons of malfunction of said gearbox arrangement 250 may be improper function of said brake means 271 and/or said lubricating pump 272 or improper function of surrounding equipment for driving said brake means 271. In these cases other certain characteristic changes of said gearbox shaft rotational speed function are presented.

Figure 4a schematically illustrates a flow chart of a method for detecting malfunction related to a gearbox arrangement 250 comprising a gearbox shaft, e.g. said main shaft 251 or lay shaft 252, attached to an additional shaft 275 fixed to said gearbox shaft, a braking means being provided for braking said additional shaft 275 and consequently said gearbox shaft. The method comprises a first method step s401. The step s401 comprises: - continuously determining a prevailing rotational speed N of said gearbox shaft; - determining a gearbox shaft rotational speed function at least after activation of said braking means 271 on the basis of said prevailing rotational speed N of said gearbox shaft; and - determining malfunction related to said gearbox arrangement 250 on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function. After the method step s401 the method ends.

Figure 4b schematically illustrates a flow chart of a method for detecting malfunction related to said gearbox arrangement 250 comprising a gearbox shaft, e.g. the main shaft 251 or the lay shaft 252, attached to an additional shaft 275 fixed to said gearbox shaft, a braking means being provided for braking said additional shaft 275 and consequently said gearbox shaft.

The method comprises a method step s410. The step s410 comprises the step of continuously determining a prevailing rotational speed N of said gearbox shaft. This can be performed by means of said rotational speed sensor 281. Alternatively said prevailing rotational speed N of said gearbox shaft can be determined in any suitable way by means of said first control unit 200 on the basis of e.g. a prevailing vehicle speed and a prevailing state of a transmission of said vehicle, including engaged gear steps of said gearbox arrangement 250. After the method step s410 a subsequent method step s420 is performed.

The step s420 comprises the step of determining a gearbox shaft rotational speed function at least after activation of said braking means 271 on the basis of said prevailing rotational speed N of said gearbox shaft. According to an embodiment said gearbox shaft rotational speed function concerns also a time period T0-T1 before said activation of said braking means 271. Hereby said first time derivative value Nlprim of said rotational speed N can be compared with said third time derivative value N3prim as basis for determining potential malfunction of said gearbox arrangement 250. If said first time derivative value Nlprim and said third time derivative value N3prim differs with less than a predetermined threshold value it may be determined that said gearbox arrangement 250 is associated with a state of malfunction. After the method step s420 a subsequent method step s430 is performed.

The step s430 comprises the step of determining malfunction related to said gearbox arrangement on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function. By identifying certain characteristics of said function it is possible to determine if a malfunction of said gearbox arrangement has occurred, and if so, which kind of malfunction is the most likely source of malfunction. It should be noted that it may be determined with a relatively high probability if said additional shaft has suffered breakage. This may be performed by identifying a sudden change of time derivative values, e.g. as exemplified at the second time point T2 with reference to Figure 3.

The method step s430 may comprise the step of determining a characteristic change of reduction of said prevailing rotational speed N of said gearbox shaft during a state of activated braking means 271 as an indication for breaking of said additional shaft 275.

The method step s430 may comprise the step of determining a characteristic change of reduction of said prevailing rotational speed N of said gearbox shaft during a state of activated braking means 271 as an indication for malfunction of said braking means 271.

After the method step s430 a subsequent method step s440 is performed.

The step s440 comprises the step of for an operator of the vehicle presenting information regarding said determined malfunction. This may be performed by means of said presentation means 290. Hereby said operator is informed so as to allow the operator to take adequate measures, such as immediately shutting down said vehicle, visit a service station, drive at low speed, park and wait for assistance, etc.

The method step s440 may comprise the step of activating an indication in case of a determined malfunction of said gearbox arrangement 250. This can be performed by means of said first control unit and said presentation means 290 After the method step s440 the method ends.

Figure 5 is a diagram of one embodiment of a device 500. The control units 200 and 210 described with reference to Figure 2 may in one embodiment comprise the device 500. 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 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). The non-volatile memory 520 has also a second memory element 540.

According to an aspect of the invention there is provided a computer program P comprising routines for detecting malfunction related to said gearbox arrangement 250 comprising a gearbox shaft, e.g. said main shaft 251 or said lay shaft 252, attached to an additional shaft 275 fixed to said gearbox shaft, a braking means 271 being provided for braking said additional shaft 275 and consequently said gearbox shaft.

The computer program P comprises routines for continuously determining a prevailing rotational speed N of said gearbox shaft attached to said additional shaft 275 and said braking means 271 and optionally said lubrication pump 272.

The computer program P comprises routines for selectively activating, de-activating and controlling operation of said braking means 271.

The computer program P comprises routines for determining a gearbox shaft rotational speed function at least after activation of said braking means 271 on the basis of said prevailing rotational speed N of said gearbox shaft attached to said additional shaft 275.

The computer program P comprises routines for determining malfunction related to said gearbox arrangement 250 on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function.

The computer program P comprises routines for determining a characteristic change of reduction of said prevailing rotational speed N of said gearbox shaft attached to said additional shaft 275 during a state of activated braking means 271 as an indication for breaking of said additional shaft 275.

The computer program P comprises routines for determining a characteristic change of reduction of said prevailing rotational speed N of said gearbox shaft attached to said additional shaft 275 during a state of activated braking means 271 as an indication for malfunction of said braking means 250.

The program P may be stored in an executable form or in compressed form in a memory 560 and/or in a read/write memory 550.

Where it is stated that the data processing unit 510 performs a certain function, it means that it conducts a certain part of the program which is stored in the memory 560 or a certain part of the program which is 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 non-volatile 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 via a data bus 511. The read/write memory 550 is arranged to communicate with the data processing unit 510 via a data bus 514. The links L210, L230, L240, L250, L281 and L290, for example, may be connected to the data port 599 (see Figure 2).

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

According to one embodiment signals received on the data port 599 comprises information about a prevailing rotational speed N of a shaft of said gearbox arrangement 250 attached to said additional shaft 275. The signals received on the data port 299 may be used by the device 500 for determining a gearbox shaft rotational speed function at least after activation of said braking means 271 on the basis of said prevailing rotational speed N of said gearbox shaft and determining malfunction related to said gearbox arrangement 250 on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function.

Parts of the methods herein described may be conducted 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.

The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive, nor to limit the invention to the variants described. Many modifications and variations will obviously suggest themselves to one skilled in the art. The embodiments have been chosen and described in order to best explain the principles of the invention and their practical applications and thereby make it possible for one skilled in the art to understand the invention for different embodiments and with the various modifications appropriate to the intended use.

Claims

1. A method for detecting malfunction related to a gearbox arrangement (250) comprising a gearbox shaft (251; 252) attached to an additional shaft (275) fixed to said gearbox shaft (251; 252), a braking means (271) being provided for braking said additional shaft (275) and consequently said gearbox shaft (251; 252), comprising the step of: characterized by the steps of: - continuously determining (s410) a prevailing rotational speed (N) of said gearbox shaft (251; 252), - determining (s420) a gearbox shaft rotational speed function at least after activation of said braking means (250) on the basis of said prevailing rotational speed (N) of said gearbox shaft (251; 252); and - determining (s430) malfunction related to said gearbox arrangement (250) on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function - determining (s430) a characteristic change of reduction of said prevailing rotational speed (N) of said gearbox shaft (251; 252) during a state of activated braking means (250) as an indication for malfunction of said braking means (271).

2. The method according to claim 1, comprising the step of: - determining (s430) a characteristic change of reduction of said prevailing rotational speed (N) of said gearbox shaft (251; 252) during a state of activated braking means (271) as an indication for breaking of said additional shaft (275).

3. The method according to claim 1 or 2, comprising the step of: - driving a gearbox lubricant pump (272) by means of said additional shaft (275).

4. The method according to any of claims 1-3, wherein said gearbox shaft is a main shaft (251) or a lay shaft (252).

5. The method according to any of claims 1-4, comprising the step of: - activating (s440) an indication in case of a determined malfunction of said gearbox arrangement (250).

6. A system for detecting malfunction related to a gearbox arrangement (250) comprising a gearbox shaft (251; 252) attached to an additional shaft (250) fixed to said gearbox shaft (251; 252), a braking means (271) being provided for braking said additional shaft (275) and consequently said gearbox shaft (251; 252), comprising: characterized by: - means (281; 200; 210; 500) for continuously determining a prevailing rotational speed (N) of said gearbox shaft (251; 252), - means (200; 210; 500) for determining a gearbox shaft rotational speed function at least after activation of said braking means (271) on the basis of said prevailing rotational speed of said gearbox shaft (251; 252); and - means (200; 210; 500) for determining malfunction related to said gearbox arrangement (250) on the basis of appearance of certain characteristic changes of said gearbox shaft rotational speed function - means (200; 210; 500) for determining a characteristic change of reduction of said prevailing rotational speed (N) of said gearbox shaft (251; 252) during a state of activated braking means (271) as an indication for malfunction of said braking means (271).

7. The system according to claim 6, comprising: - means (200; 210; 500) for determining a characteristic change of reduction of said prevailing rotational speed (N) of said gearbox shaft (251; 252) during a state of activated braking means (271) as an indication for breaking of said additional shaft (275).

8. The system according to claim 6 or 7, comprising: - a gearbox lubricant pump (272) arranged to be driven by means of said additional shaft (275).

9. The system according to anyone of claims 6-8, wherein said gearbox shaft (251; 252) is a main shaft (251) or a lay shaft (252).

10. The system according to anyone of claims 6-9, comprising: - means (200; 210; 500; 290) for activating an indication in case of a determined malfunction of said gearbox arrangement (250).

11. A vehicle (100; 110) comprising a system according to anyone of claims 6-10.

12. The vehicle (100; 110) according to claim 11, which vehicle is any from among a truck, bus or passenger car.

13. A computer program (P) for detecting malfunction related to a gearbox arrangement (250), wherein said computer program (P) comprises program code for causing an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500) to perform the steps according to anyone of the claims 1-5.

14. A computer program product containing a program code stored on a computer-readable medium for performing method steps according to any of claims 1-5, when said computer program is run on an electronic control unit (200; 500) or a computer (210; 500) connected to the electronic control unit (200; 500).