DE102018221590A1 - Method for recognizing an elongation of a force-transmitting chain between an input and an output of a vehicle - Google Patents

Abstract

The invention relates to a method for recognizing an elongation of a power transmission chain (110) between a drive (120, 125, 130) and an output (140, 145) of a vehicle the chain sweeps during a load change, the determined angle of rotation size is determined, the angle of rotation size being evaluated and the elongation of the chain (110) being recognized therefrom.

Description

The present invention relates to a method for recognizing an elongation of a force-transmitting chain between a drive and an output of a vehicle, and to a computing unit and a computer program for carrying it out.

State of the art

For example, in two-wheel vehicles such as motorcycles, chains are often used to transmit power between the drive and output. The output mostly represents the rear wheel of the vehicle, the drive mostly internal combustion engines. The use of electrical machines in hybrid vehicles is also widespread. Such a power transmission by means of a chain is also often used in vehicles such as quads or trikes.

Due to aging, wear effects of the chain in the form of elongation can occur. If this elongation is too great, the chain must be retensioned so that the driveability is not negatively affected and the chain cannot be skipped or dropped. The chain elongation is usually checked manually in workshops or by the driver of the vehicle himself. Automatic determination of chain elongation, particularly during regular vehicle operation, is desirable.

Disclosure of the invention

Against this background, a method for recognizing an elongation of a force-transmitting chain between a drive and an output of a vehicle, as well as a computing unit and a computer program for carrying it out, are proposed with the features of the independent claims. Advantageous embodiments are the subject of the subclaims and the following description.

The method is particularly suitable for various types of vehicles in which force is transmitted by means of a chain between a drive, such as an internal combustion engine and / or an electrical machine, and an output, in particular directly to one or more wheels of the vehicle or to an output shaft on which wheels are arranged. The method is particularly suitable for two-wheel vehicles such as motorcycles, scooters, mopeds etc. The method is also suitable for ATVs (all-terrain vehicles) such as quads, trikes etc.

Within the scope of the method, a chain elongation is recognized on the basis of a rotation angle variable characterized by a rotation angle that the drive sweeps during a non-force-transmitting movement of the chain during a load change, and preferably also determined quantitatively. A load change is a change of load strand and empty strand. The size of the angle of rotation can in particular be the angle of rotation itself or a gradient of the angle of rotation, that is to say speed.

The invention is based on the finding that an elongation of the chain has a detectable and quantifiable effect on the angle of rotation swept over during the load change. Depending on the gear engaged and the chain length, for an exemplary measured motorcycle, the rotation angle swept during a complete load change changes, for example, by approximately 1.8 ° KW / mm (6th gear) up to 5.4 ° KW / mm (1st gear ). For example, the present method enables an automatic check for an elongation of the chain to be carried out during regular operation of the vehicle, in particular without manual intervention by a user. In particular, the monitoring of the chain elongation can be carried out automatically at predetermined time intervals, for example during each journey with the vehicle or after a predetermined number of kilometers or driving hours. In particular, permanent monitoring is also conceivable.

Chain elongation can be detected early by the method and appropriate countermeasures can be taken or initiated in good time, for example retensioning the chain, so that driveability is not negatively influenced and the chain cannot be skipped or dropped. When chain elongation is detected, for example, an error entry can be stored in a control unit and / or the driver can be informed of the elongation present by means of a suitable interface (English: Human Machine Interface, HMI), for example by a display in a dashboard area of the vehicle.

The angle of rotation is expediently recorded on the crankshaft, since appropriate sensors are usually present anyway.

The angle of rotation size is advantageously compared with a reference angle of rotation size in the course of the evaluation. This reference angle of rotation characterizes in particular a chain without elongation. For example, the reference angle of rotation size can be corresponding values of the angle of rotation size, which were determined when the vehicle or the chain was in new condition. Differences between the currently determined values of the angle of rotation size and the size of the reference angle of rotation thus point in particular to an elongation the chain and expediently allow a quantification of the elongation.

As an alternative or in addition, an absolute evaluation of the angle of rotation size is preferably also conceivable. For example, the angle of rotation size can in this case be subjected to a threshold value comparison in the course of the evaluation, wherein reaching the threshold value expediently indicates an elongation of the chain. In particular, a plurality of threshold values can also be provided, wherein the reaching of the different threshold values indicates different elongations and thus expediently a quantification of the elongation is made possible.

The size of the angle of rotation is preferably determined during a coasting operation of the drive, in particular thus during the drive with a non-separate frictional connection, e.g. when the clutch is not depressed, is dragged, i.e. is kept rotating. The overrun mode represents a particularly suitable operating scenario of the drive during which the chain elongation can be inferred. In the course of the overrun operation, the drive, which is designed in particular as an internal combustion engine, carries out expansion and compression phases in its cylinder or cylinders, which expediently allow conclusions to be drawn about the chain elongation. In particular, such load changes occur not only when there is a change between fired and unfired operation or overrun operation and train operation, but also in unfired overrun operation when there is a change between compression and expansion of a cylinder. The corresponding angles of rotation lead to fluctuations in speed. In particular, the non-force-transmitting movement of the chain can be recognized from the fluctuation in the speed of the drive.

Advantageously, the amount of rotation angle during coasting is determined as a difference between a first speed during compression of the drive and a second speed during expansion of the drive. In this case, the drive is preferably designed as an internal combustion engine, the compression or expansion taking place in one or more cylinders of the internal combustion engine. In the course of the overrun operation, the speed is particularly reduced during the compression and in particular the speed is increased during the expansion. By comparing the first speed, which in particular characterizes this reduction in speed in compression, with the second speed, which characterizes in particular this speed increase in expansion, it can expediently be concluded that the chain is elongated to a greater extent. In particular, the difference between the first and second speed can be compared for this purpose with a threshold value or reference value. This difference is expediently evaluated in a low gear, in particular in the first, second or third gear, since the effects of chain elongation on the difference are most evident in these low gears.

During thrust operation, a throttle valve of the drive is preferably controlled in such a way that at least 90%, preferably at least 95% or 100% of the maximum filling is achieved. It is therefore expedient to achieve a high or maximum compression work during the compression due to a high or maximum degree of filling of the cylinder, as a result of which the speed difference between compression and expansion is increased, which allows a clear and precise conclusion to be drawn about the chain elongation. Conversely, the throttle valve can preferably be completely closed during the overrun operation or controlled in such a way that at most 10%, preferably at most 5%, of the maximum filling is achieved. In this case, the speed during the compression can in particular rise due to a negative pressure in the cylinder and expediently decrease in the expansion.

The angle of rotation magnitude is preferably determined during a load change from a pulling operation to a pushing operation or from a pushing operation to a pulling operation of the drive. Such a load change expediently represents a transition between the overrun mode during which the drive is being towed and the train mode during which the drive actively drives the vehicle and generates a torque which is transmitted to the wheels of the vehicle. Such a load change also represents a particularly suitable operating scenario in order to be able to draw conclusions about the chain elongation. In such load changes, the so-called “loose” comes into play, a movement of the chain during which, due to its elongation, the chain cannot transmit any force before the chain is tensioned and can again be used for power transmission.

According to an advantageous embodiment, an internal combustion engine of the vehicle is deactivated and an electrical machine of the vehicle is activated.

A gear is also engaged, preferably the first gear. In this case, the electrical machine advantageously rotates the chain in a first direction up to a first stop and then in a second direction up to a second stop. For example, in this case the electrical machine can be designed as a starter generator or also as a generator or Motor-operated electrical machine of a hybrid vehicle.

This special operating mode of the internal combustion engine and the electrical machine also represents a particularly suitable operating scenario for recognizing chain elongation. For example, this operating scenario can be carried out each time the vehicle is switched off if an engine oil is expediently still warm and there is little friction. Alternatively or additionally, the chain elongation detection can be triggered in this scenario if certain conditions exist, e.g. when the drive train is closed, first gear engaged and a vehicle brake applied, for example when the vehicle is at a red light.

The first and the second stop characterize in particular the rotational positions from which the chain transmits force in the respective direction. In this operating scenario, the chain is expediently rotated by the electrical machine in the respective direction until an increase in resistance occurs. The stops can thus be recognized, for example, by the load or the resistance that the electrical machine experiences. In particular, the movement of the chain between the first and the second stop characterizes the movement of the chain during which the chain does not transmit any force.

The first stop and / or the second stop are preferably determined with the aid of an electrical variable of the electrical machine. For example, the electrical quantity can be a current through the electrical machine or a stator voltage, battery voltage etc. The load or the resistance which the electrical machine experiences when it reaches a stop is particularly reflected in this electrical quantity. Furthermore, a load characteristic curve which is established can expediently be used in the stops in order to determine wear on damper elements arranged in the drive train. For example, damper elements (or drive shock absorbers) are partially installed in the rear wheel hub in 2-wheelers in order to make the driving behavior more harmonious and comfortable for the driver. In addition to chain elongation, these dampers also play a role. In the event of excessive wear of these damping elements (= larger loose or worn dampers), the state of the damping elements can then be shot using the method described here.

A computing unit according to the invention, e.g. a control unit of a motor vehicle is, in particular in terms of programming, set up to carry out a method according to the invention.

The implementation of a method according to the invention in the form of a computer program with program code for carrying out all method steps is also advantageous, since this causes particularly low costs, in particular if an executing control device is still used for further tasks and is therefore present anyway. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as Hard drives, flash memory, EEPROMs, DVDs etc. It is also possible to download a program via computer networks (internet, intranet, etc.).

Further advantages and refinements of the invention result from the description and the attached drawing.

The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing.

Figure list

• 1 schematically shows a drive train of a motor vehicle with a drive, a force-transmitting chain and an output, which can be the basis of a preferred embodiment of a method according to the invention.
• 2nd to 4th each schematically shows a preferred embodiment of a method according to the invention as a block diagram.

Embodiment (s) of the invention

In 1 is a schematic of a powertrain 100 of a vehicle. The vehicle can be designed, for example, as a two-wheeled vehicle, such as a motorcycle, scooter, moped, etc., or, for example, as an ATV (all-terrain vehicle), such as a quad, trike, etc.

An internal combustion engine 120 with a crankshaft 125 is provided as a drive of the vehicle, which can generate a torque for driving the vehicle. There is also an electrical machine 130 provided which, alternatively or in addition to the internal combustion engine, the crankshaft 125 can set in rotation. The electrical machine 130 can be designed, for example, as a starter generator or as a motor or electrically operated electrical machine of a hybrid vehicle.

The crankshaft 125 is connected to a transmission input of a transmission, in particular a manual transmission. A chain 110 is for power transmission between a transmission output of the Gearbox and an output provided, for example an output shaft 145 on which a wheel 140 of the vehicle is arranged.

A computing unit 150 , for example an engine control unit, is used to control or regulate the drive, that is to say the internal combustion engine 120 as well as the electrical machine 130 intended.

The control unit 150 is also provided to automatically lengthen the chain while the vehicle is in operation 110 to be able to recognize. For this purpose the control unit 150 , in particular in terms of programming, set up to carry out a preferred embodiment of a method according to the invention, as in the 2nd to 4th each is shown schematically as a block diagram.

According to a preferred embodiment of the invention, the elongation detection can be carried out during a coasting operation of the vehicle, as schematically shown in FIG 2nd is shown.

In step 210 the vehicle is operated in normal operation, ie the internal combustion engine 120 drives over the chain 110 the wheel 140 on. In step 220 the vehicle switches to overrun, in the course of which the internal combustion engine 120 is towed if the adhesion is not separated.

During the overrun operation is in step 230 an angle of rotation size, characterized by an angle of rotation that the drive sweeps during a non-force-transmitting movement of the chain during a load change, as a difference between a first rotational speed during a compression of the internal combustion engine 120 and a second speed during expansion of the internal combustion engine 120 certainly. The load strand and empty strand of the chain alternate between compression and expansion. The difference in speed is greater, the greater the angle of rotation swept by the non-force-transmitting movement of the chain.

For this purpose, a low gear is also engaged, for example the first to third gear, and a throttle valve of the internal combustion engine 110 will open fully. During the compression in the cylinder of the internal combustion engine 120 the speed is reduced and increased in the expansion. This speed difference is in step 230 determined as a rotation angle quantity and in step 240 evaluated.

For example, this angle of rotation size is part of this evaluation 240 compared with a reference angle of rotation size, for example with a reference value for the speed difference for a chain when new. If the currently determined speed difference does not deviate from this reference value by more than a predetermined value of, for example, 5%, then in step 250 determines that no chain elongation 110 is present.

If, on the other hand, the currently determined speed difference deviates from the reference value by more than the specified value of, for example, 5%, the step 260 determines that an elongation of the chain 110 is present. In this case, step 270 for example, an error entry in the control unit 150 created and a warning lamp in a dashboard area of the vehicle is activated to inform the driver of the elongation.

Alternatively or additionally, according to a preferred embodiment of the invention, the elongation detection can also be carried out during a load change, as for example in FIG 3rd is shown.

In one step 310 the vehicle is towed, for example, in a push operation. In step 320 there is a load change from this overrun mode to a train or load mode. The load strand and empty strand of the chain also change.

During this load change, the chain 110 initially not moving before the chain 110 can transmit power again. This non-force-transmitting movement (so-called “loose”) is a measure of the lengthening of the chain 110 in step 330 Therefore, during the load change, the rotation angle that is swept is determined as the rotation angle variable from the speed. The swept angle of rotation or the speed can be determined as usual, for example by evaluating the so-called tooth times. For this purpose, a sender wheel with teeth and gaps rotates with the crankshaft, which, for. B. is scanned magnetically to determine tooth-gap change and from this the tooth times. To obtain the highest possible resolution, encoder wheels with many teeth, eg so-called 36-2 (2 missing teeth = gap), are advantageous.

During the bridging of the slack during the transition from thrust to drive, the chain will accelerate very quickly due to the slack and therefore very little resistance, if a driving moment is caused by the combustion. The chain acceleration can be recorded as crankshaft acceleration. The unusually quickly swept angular range is a measure of the lots.

In step 340 this angle of rotation size becomes analogous to step 240 evaluated and with a reference value of a new chain 110 compared. As explained above in step 350 determines that the chain is not elongated if the currently determined value of the angle of rotation does not deviate from the reference value by more than, for example, 5%. If, on the other hand, the currently determined value deviates by more than 5%, for example, in step 360 determines that there is elongation and in step 370 an error entry is created and the warning lamp is activated.

According to one in 4th shown preferred embodiment of the invention, the elongation detection is carried out when the vehicle is parked or deactivated.

In step 410 the vehicle is switched off after regular operation, ie the internal combustion engine 120 is deactivated. In step 420 thereupon with the internal combustion engine deactivated 120 and still activated electrical machine 130 a gear is engaged, especially the first gear. The electrical machine 130 now turns the chain 110 in a first direction up to a first stop and then in a second direction up to a second stop. In step 430 a rotation angle is determined as the rotation angle quantity characterized by the rotation angle which the drive traverses during a non-force-transmitting movement of the chain during a load change, around the chain 110 to move from the first stop to the second stop.

In accordance with the above explanations, this rotation angle quantity becomes in step 440 evaluated and compared with a reference value of a new chain. If the current value does not deviate from the reference value by more than 5%, for example, in step 450 determines that there is no elongation. However, if the current value deviates by more than 5%, in step 460 determines that there is elongation. In step 470 an error entry is then created and the warning lamp is activated.

Claims (13)

Method for recognizing an elongation of a force-transmitting chain (110) between a drive (120, 125, 130) and an output (140, 145) of a vehicle, wherein an angle of rotation size characterized by an angle of rotation that the drive sweeps during a non-force-transmitting movement of the chain during a load change is determined (220, 320, 420), wherein the angle of rotation size is evaluated and the elongation of the chain (110) is recognized therefrom (240, 340, 440). Procedure according to Claim 1 , the angle of rotation size being compared in the course of the evaluation with a reference angle of rotation size and / or with a threshold value (240, 340, 440). Procedure according to Claim 1 or 2nd wherein the amount of rotation angle is determined during a coasting operation of the drive (220). Procedure according to Claim 3 wherein, during coasting, the angle of rotation amount is determined as a difference between a first speed during compression of the drive (120) and a second speed during expansion of the drive (120). Procedure according to Claim 3 or 4th , wherein a throttle valve of the drive is activated during the overrun operation in such a way that at least 90%, in particular at least 95% or maximum filling is achieved. Method according to one of the preceding claims, wherein the angle of rotation size is determined (320) during a load change from a pulling operation to a pushing operation or from a pushing operation to a pulling operation of the drive (120). Method according to one of the preceding claims, wherein an internal combustion engine (120) of the vehicle is deactivated, an electrical machine (130) of the vehicle is activated and a gear is engaged (410), wherein the electrical machine (130) the chain (110) in rotates a first direction to a first stop and then rotates in a second direction to a second stop (420). Procedure according to Claim 7 , wherein the angle of rotation size is determined as a function of an angle of rotation difference between the first stop and the second stop (420). Procedure according to Claim 7 or 8th , the first stop and / or the second stop being determined with the aid of an electrical variable of the electrical machine (130). Method according to one of the preceding claims, wherein the drive is designed as an internal combustion engine (120) and / or as an electrical machine (130). Computing unit (150) which is set up to carry out all method steps of a method according to one of the preceding claims. Computer program which causes a computing unit (150) to carry out all method steps of a method according to one of the Claims 1 to 10th to be carried out when it is executed on the computing unit (150). Machine-readable storage medium with a computer program stored on it Claim 12 .

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