Method of and apparatus for determining the tractive force of a trackbound, driven system

The invention relates to a method for determining a tensile force of a track-bound, driven system comprising at least one vehicle and an apparatus for performing the method, with the features mentioned in the preamble of claim 8.

Methods and apparatus for determining a tensile force of a track-bound, driven system are known. Under track-bound, powered systems, for example, rail-bound trains that comprise at least one traction unit, speed railways, maglev trains or the like understood. These systems are moved by at least one traction vehicle along a predetermined route. Usually, such track-bound, driven systems operate in a timetable, that is, at fixed times, these systems must have a certain position on the known route. For this purpose, these systems move at a speed along the route. In order to achieve this necessary speed, the application of a driving force is necessary, by means of which the system is set in motion. The required drive energy is dependent on a topography of the route, such as gradients, gradients, curves or the like and on the other hand of parameters of the system itself, such as mass or the like.

When used according to the purpose of the generic track-bound, driven systems, these have a certain, known drive power. For the integration of the systems in a clock schedule is now required to check whether this drive power is sufficient, according to the given system parameters and track topography sufficient driving force (hereinafter tensile force) apply. Used traction vehicles have a tensile force characteristic that includes the tensile force over the speed. For determining this tensile force characteristic curve or for checking a predetermined tensile force characteristic, it is known to determine a momentary tensile force during a drive of the driven system. For determining the tensile force, a so-called Meßradsatz method, a hollow shaft method and a towing hook measuring method is known. In the case of the measuring wheel set method, longitudinal, transverse and contact forces between the wheel and rail can be detected by the wheel sets involved in the tractive force transmission. The measured tensile forces result from elastic deformations of wheelsets and wheels, which are detected by means of strain gauges and converted by means of a computer in the acting on the wheel longitudinal and transverse forces. In the hollow shaft method, the tractive forces in both wheel contact points of a wheel set are determined by measurements of a hollow shaft torque and the known radius of the wheels of the wheels of single-sided cardan hollow shaft drives. For this purpose, the arrangement of strain gauges on the hollow shaft is required. In the known towing hook measuring method, the traction vehicle is connected to a trailer load (other vehicles, cars of a train) via a Zugkraftmeßkupplung. This Zugkraftmeßkupplung comprises bending and temperature compensated strain gauges, by means of which acting on the coupling tensile forces can be detected.

In the known tensile force measuring method is disadvantageous that they require a very complex measuring device for direct measurement of tension. A further disadvantage is that to determine a resulting tensile force of all wheels a corresponding number of Zugmeßeinrichtungen is provided, the individual measurement results must be added. In the Meßradsatz method, a total of eight Radumfangskräfte and the hollow shaft method four Radumfangskräfte must be considered. In addition to this additional sources of error is disadvantageous that not only the static components of the torques occurring, but also dynamic portions of the torques are detected, which occur as natural modes of the drive train. As a result, these methods are subject to an error.

When using a Zugkraftmeßkupplung is disadvantageous that this is only possible in powered systems with a traction unit and attached to the locomotive vehicles as a load.

Another disadvantage of the known methods is that they can not be used in track-bound, driven drive systems with track-bound, driven systems without direct physical contact between the system and the travel path, such as magnetic levitation railways.

From IMAR, society inertial measuring, automation and control systems, measuring system for inertial kinematic measurement, Version 1.5, 1997 inertial measuring systems are known, by means of which accelerations, rotation rates and angles of a moving body can be determined.

According to DE-OS 42 28 413 a method for determining the mass of a moving forces by sales forces in its longitudinal direction motor vehicle is known, wherein<ul id="ul0001" list-style="dash" compact="compact"><li>at least two longitudinal accelerations are detected at at least two different times, and</li><li>the propulsive forces present at those times are recorded, and</li><li>from the difference of the sales forces and the difference of the longitudinal accelerations the vehicle mass is determined.</li></ul>

This method is exclusively related to road vehicles, the mass of this vehicle. is determined. The mass is only important for determining the acceleration force. For all other criteria, including the driving resistance, the mass of a vehicle is not relevant.

The invention has for its object to provide a method and apparatus for determining a tensile force of a track-bound, driven system, by means of which a metrological effort is reduced while maintaining high accuracy and its use in all track-bound, driven systems is possible.

According to the invention this object is achieved by a method having the features mentioned in claim 1. The fact that the current total driving resistance of the track-bound, driven system is detected and from this the tensile force is determined, it is advantageously possible to determine the traction indirectly over the total driving resistance, so that can be dispensed with expensive direct force measuring arrangements. Since the applied tractive force when driving the driven system with a certain speed corresponds exactly to the total driving resistance to be overcome, it is thus possible in a simple manner to determine the actual instantaneous tractive force by determining the total driving resistance. Overall, therefore, a measuring method is provided which can determine a tensile force with high accuracy in real time with a reduced measurement effort.

In a preferred embodiment of the invention, it is provided that the instantaneous Gesamtfahrwiderstand is determined from a sum of instantaneous individual driving resistances, in particular as a single running resistances a running resistance, an arc resistance, a pitch resistance and an acceleration resistance are determined. By such a determination of the total driving resistance can be easily determine the driving resistance of the entire track-bound, driven system, that is, of all the individual vehicles of the system. As a result, the total driving resistance can be determined with high accuracy, since all components of the entire system influencing this driving resistance, ie all individual vehicles of the system, are taken into account in the determination.

By means of the method according to the invention, it is possible to determine the momentary pulling force at all times, knowing a current speed, which can be determined by measuring methods known per se. By deriving the instantaneous tensile force from the instantaneous total driving resistance, a direct force measurement is not required. As a result, a substantial simplification of the entire measurement method is possible. In particular, even with distributed drives so the instantaneous tensile force of the entire driven system can be determined.

According to the invention the object is further achieved by a device having the features mentioned in claim 8. Characterized in that at least one system fixedly arranged inertial measuring system for determining the instantaneous acceleration of the system in the three spatial directions and the instantaneous rates of rotation about the three spatial axes and a measuring device for determining the instantaneous speed of the system and a detection and evaluation unit for determining a current total driving resistance provided are, can be tapped in a simple manner required for the determination of the current Gesamtfahrwiderstandes measured variables, so that on the detection and evaluation unit without direct force measurement, the instantaneous tensile force of the system is enmittelbar.

Further preferred embodiments of the invention will become apparent from the remaining features mentioned in the dependent claims.

The invention will be explained in more detail in an embodiment with reference to the accompanying drawings. Show it:<dl id="dl0001"><dt>FIG. 1</dt><dd>schematically a track bound, powered system;</dd><dt>FIG. 2</dt><dd>a block diagram of a device for determining a tensile force of the system;</dd><dt>FIG. 3</dt><dd>a determined by the method according to the invention tensile force characteristic;</dd><dt>FIG. 4</dt><dd>Characteristic curves of individual driving resistances of the system;</dd><dt>FIG. 5</dt><dd>a determined by the method according to the invention gradient of a pitch resistance;</dd><dt>FIG. 6</dt><dd>schematically a concrete embodiment of a system and</dd><dt>FIG. 7</dt><dd>schematically a system according to another embodiment.</dd></dl>

1 schematically shows a track-bound, driven system 10 (hereinafter also referred to as train 10), which comprises a total of three vehicles 12. Of course, further embodiments with fewer or more than three vehicles 12 are possible. Within the system 10, at least one of the vehicles 12 is a traction vehicle, that is, via this, a drive energy for movement of the system 10 along a route 14 in the direction of travel 16 can be applied. The necessary for this purpose, unspecified drive system comprises at least one drive, possibly also a plurality of drives which act on one or more of the wheelsets 18. If necessary, distributed drives are present, that is, the drive energy is applied via wheelsets 18 of several vehicles 12 of a system 10 at the same time. The route 14 is known to consist of a arranged on a corresponding substructure track with two rails. The route 14 is laid according to topographical conditions, that is, the route 14 may have slopes and gradients and arcs with different radii.

The system 10 is a track bound system, regardless of how the drive energy is applied. These may be, for example, rail-bound systems (high-speed trains, freight trains, railways or the like) or magnetic levitation trains in which there is no direct physical contact between the system 10 and the route 14.

The system 10 comprises a total of 20 designated device for determining a current tractive force of the system 10. By instantaneous tensile force is the tensile force at any time t, in which the system 10 at any speed v in the direction of travel 16 along the route 14 moves, is required.

FIG. 2 shows a block diagram of the device 20. The device 20 comprises an inertial measuring system 22, a speed measuring device 24 and a detection and evaluation unit 26. A first signal output 28 of the speed measuring device 24 is connected to an input 30 of the inertial measuring system 22. A second signal output 32 of the speed measuring device 24 is connected to a first input 34 of the detection and evaluation unit 26. A signal output 36 of the inertial measuring system 22 is connected to inputs 38, 40 and 42 of the detection and evaluation unit 26.

The detection and evaluation unit 26 includes circuit components 44, 46, 48, 50, 52, 54, 56 and 58, whose meaning and function will be discussed in more detail below.

The device 20 in connection with the system 10 has the following function:

By means of the device 20, the instantaneous tensile force of the system 10 is to be determined. This is based on the initial consideration that in order to move the system 10 in the direction of travel 16, this requires a traction that overcomes all of the system 10 acting driving resistances. In this case, the tractive force is transmitted via the driven wheel sets 18, optionally a plurality of wheel sets 18, which may be distributed over the individual vehicles 12, to the travel path 14 (rails) in the direction of travel 16. According to the number of driven wheelsets 18 act Teilzugkräfte, the sum of the total tensile force of the system 10. When moving the system 10 in the direction of travel 16, the tensile force F_to equal to the total travel resistance F_wso that<maths id="math0001" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">to</mtext></mrow></msub><mtext>= </mtext><msub><mrow><mtext mathvariant="italic">-F</mtext></mrow><mrow><mtext mathvariant="italic">w</mtext></mrow></msub></mrow></math><img file="EP1111359B1_D0001.tif" /></maths>

Since the total driving resistance F_w the traction is opposite, this is negative with respect to the direction of travel 16.

From this relationship it is clear that the tensile force of the system 10 without direct force measurement, as previously used exclusively in the prior art, by determining the total driving resistance F_w of the system 10 is possible.

The total driving resistance F_w of the system 10 is composed of a sum of individual driving resistances, where:<maths id="math0002" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">w</mtext></mrow></msub><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">wl</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> + F</mtext></mrow><mrow><mtext mathvariant="italic">wb</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> + F</mtext></mrow><mrow><mtext mathvariant="italic">wn</mtext></mrow></msub><msub><mrow><mtext mathvariant="italic"> + F</mtext></mrow><mrow><mtext mathvariant="italic">wa</mtext></mrow></msub><mtext>.</mtext></mrow></math><img file="EP1111359B1_D0002.tif" /></maths> with F_wl equal running resistance of the system 10, F_wb Sheet resistance of the system 10, F_wn Tilt resistance of system 10 and F_wa Acceleration resistance of the system 10. The running resistance F_wl and the sheet resistance F_wb are always positive, while the slope resistance F_wn (at gradient) and the acceleration resistance F_wa (in case of delay), positive and negative values ​​can be assumed.

These individual driving resistances of the system 10 can be determined either for the entire system 10 by means of a device 20. According to a further embodiment, it can be provided that the individual driving resistances for each vehicle 12 of the system 10 are determined separately. For this purpose, a corresponding number of detection and evaluation units 26, each associated with a vehicle 12, would then be required. When determining the individual driving resistances, only one inertial measuring system 22 and one speed measuring device 24 at a certain point of the system 10 are required. At this point, the inputs of the circuit components 44, 46, 48, 52, 54 and 50 are measured and latched. To determine the individual driving resistances, the knowledge of the distances s_i the individual vehicles 12 (or their bogies) necessary. The output variables of the inertial measuring system 22 are then calculated taking into account the distance s_i (Figure 7) assigned to the circuit components of the individual vehicles and thus determines the individual driving resistances. With the same arrangement, the Einzeifahrwiderstände for driven and non-powered vehicles can be determined separately.

In the context of the invention is also when the tensile force of a system 10 is determined by when the tensile force for at least one driven vehicle via the determination of the total driving resistance and the required traction for non-powered vehicles by a direct Zugkraftmessung, for example, after the known tow hook -Meßverfahren, is determined. By summation of the individual driving resistances that can be determined in this way, the overall travel resistance of the system 10, via which, as already explained, the tensile force F results_to can be recognized.

The individual driving resistances are dependent on a number of boundary conditions, which are known in a particular system 10, however. So is the running resistance F_wl the sheet resistance F_wb and the pitch resistance F_wn approximately proportional to the weight G, while the acceleration resistance F_wa is linearly linked to the mass m of the system 10. Furthermore, the running resistance F_wl Depending on the aerodynamic shape of the system 10, which is characterized by the product of air resistance C_w and express cross-sectional area A in the direction of travel 16.

This results in a general relationship for the total travel resistance:<maths id="math0003" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">w</mtext></mrow></msub><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">(w</mtext></mrow><mrow><mtext mathvariant="italic">l</mtext></mrow></msub><mtext> + </mtext><msub><mrow><mtext mathvariant="italic">w</mtext></mrow><mrow><mtext mathvariant="italic">b</mtext></mrow></msub><mtext> + </mtext><msub><mrow><mtext mathvariant="italic">w</mtext></mrow><mrow><mtext mathvariant="italic">n</mtext></mrow></msub><mtext mathvariant="italic">) ·</mtext><mtext>G +</mtext><msub><mrow><mtext mathvariant="italic">w</mtext></mrow><mrow><mtext mathvariant="italic">a</mtext></mrow></msub><mtext mathvariant="italic">.</mtext><mtext> m,</mtext></mrow></math><img file="EP1111359B1_D0003.tif" /></maths> where w_l the specific running resistance, w_b the specific arc resistance, w_n the specific tilt resistance, w_a the specific acceleration resistance, m is the mass and G is the weight of the system 10.

By means of the circuit component 44 (FIG. 2) of the detection and evaluation unit 26, the acceleration resistance is determined. The relationship applies here.<maths id="math0004" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">wa</mtext></mrow></msub><mtext> =</mtext><msub><mrow><mtext mathvariant="italic">m · a</mtext></mrow><mrow><mtext mathvariant="italic">x</mtext></mrow></msub><mtext> (ρ + 1),</mtext></mrow></math><img file="EP1111359B1_D0004.tif" /></maths> where a_x the load on the system 10 in the direction of travel 16, m is the mass of the system 10, and ρ is a weighting factor for a rotational mass fraction of the system 10. The mass m and the weighting factor p are known as the constant of the system 10. The acceleration a_x is provided at the entrance 42 of the inertial measuring system 22, in a manner to be explained in more detail later.

The acceleration resistance F_wa is proportional to the force that must be applied for a change in speed. When the system 10 is moving steadily, the acceleration resistance F is_wa unavailable. During acceleration of the system 10, an inertial force to be overcome, which is referred to as the damping resistance F_wa can be considered. In this case, in addition to the translation acceleration of the total mass m, an angular acceleration of the rotating masses of the system 10 must also be taken into account. The rotational energy of the rotating masses can each be replaced by the translational energy of an additional mass. Where:<maths id="math0005" num=""><math display="block"><mrow><mfrac><mrow><mtext>Δ</mtext><msup><mrow><mtext mathvariant="italic">m * v</mtext></mrow><mrow><mtext>2</mtext></mrow></msup><mtext></mtext></mrow><mrow><mtext>2</mtext></mrow></mfrac><mtext>=</mtext><mfrac><mrow><msup><mrow><mtext mathvariant="italic">J * w</mtext></mrow><mrow><mtext>2</mtext></mrow></msup><mtext></mtext></mrow><mrow><mtext>2</mtext></mrow></mfrac></mrow></math><img file="EP1111359B1_D0005.tif" /></maths> where J is the rotational mass moment of inertia. Taking into account the ratio i of a gearbox, one can calculate the force needed to accelerate the mass m, including the sum of the individual rotating masses, according to the relationship<maths id="math0006" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">wa</mtext></mrow></msub><mtext> = </mtext><mtext mathvariant="italic">m</mtext><mtext>·</mtext><mtext mathvariant="italic">a</mtext><mtext>+∑</mtext><msub><mrow><mtext mathvariant="italic">J</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></msub><mtext>·</mtext><msup><mrow><mfenced open="(" close=")"><mrow><mfrac><mrow><mtext>2·</mtext><mtext mathvariant="italic">i</mtext><msub><mrow><mtext>​</mtext></mrow><mrow><mtext mathvariant="italic">l</mtext></mrow></msub></mrow><mrow><mtext mathvariant="italic">D</mtext><msub><mrow><mtext>​</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></msub></mrow></mfrac></mrow></mfenced></mrow><mrow><mtext>2</mtext></mrow></msup><mtext> ·</mtext><mtext mathvariant="italic">a</mtext><mtext>=</mtext><mtext mathvariant="italic">m</mtext><mtext>· (Ρ + 1) *</mtext><msub><mrow><mtext mathvariant="italic">a</mtext></mrow><mrow><mtext>x</mtext></mrow></msub></mrow></math><img file="EP1111359B1_D0006.tif" /></maths> to calculate. As a result, it is thus possible to know the mass m of the weighting factor p and the acceleration a_x in the direction of travel 16, the acceleration resistance F_wa of the system 10. The factor p is, for example, 0.02 to 0.12 for passenger coaches and freight cars, 0.08 to 0.18 for electric railcars, 0.15 to 0.30 for electric locomotives and 0.06 to 0.30 for the average of a locomotive train 0.10. The size of the weighting factor p for the rotary mass fraction is weighted according to a total mass m of the system. For empty or loaded (passengers, goods to be transported) systems 10 results in a different weighting factor p of the rotational mass fraction, since the total mass m changes with the load of the system 10.

By means of the circuit component 46 (FIG. 2) of the detection and evaluation unit 26, the inclination resistance F_wn of the system 10. The inclination resistance F_wn is the counter to the direction of movement 16 positively counted component of the weight G of the train, the so-called slope force. In the plane, the inclination resistance is F_wn = 0. The inclination resistance F_wn turns out<maths id="math0007" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">F</mtext></mrow><mrow><mtext mathvariant="italic">wn</mtext></mrow></msub><mtext mathvariant="italic">=</mtext><mtext>sin</mtext><mtext mathvariant="italic">β · m · g</mtext></mrow></math><img file="EP1111359B1_D0007.tif" /></maths> where β is the inclination angle of the route 14, m is the mass of the system and g is the gravitational acceleration. The angle of inclination β is provided by the inertial measuring system 22 at the input 40 of the detection and evaluation unit 26, as will be explained below. The mass m and the gravitational acceleration g are known as constants.

By means of the circuit components 48, 52 and 54 (FIG. 2) of the detection and evaluation unit 26, the sheet resistance F_wb of the system 10. The sheet resistance F_wb arises in addition to the running resistance Fwl by the course of the system 10 in track curves. In the case of bow travel, the effect of the centrifugal forces creates lateral forces between the wheel and the rail. The centrifugal forces increase quadratically at increasing speed v and are compensated, for example, in part by civil engineering measures, for example an elevation of the curve-outside rail of the travel path 14.

The sheet resistance F_wb is an additional frictional resistance that arises when driving on track curves. The cause lies in the unequal way the rigidly connected wheels (inner wheel and outer wheel at Bogenfahrt) of the wheelsets 18. The given by the rigid connection of the wheels tracking the wheelsets leads to an inclination of the wheelsets at bow travel, which lead to an increase in the frictional resistance. Furthermore, the flange of the outer wheel is pressed at arc travel by the centrifugal force against the rail, so that a further frictional resistance is given.

The sheet resistance F_wb is thus dependent on the geometric conditions of the route 14, in particular the radius of curvature r, the gauge of the route 14, the elevation of the outer rail and a track extension in the bow. Further, the arc resistance F_wb of the vehicles 12 of the system 10, such as a wheelbase, a Radialeinstellbarkeit the wheelsets 18 dependent. Further, the arc resistance F_wb from a condition of the wheel-rail contact, for example as a result of flange and / or rail wear, the effect of a wheel flange lubrication, wet or dry rails depending.

The sheet resistance F_wb is proportional to the gauge t_sp, It follows<maths id="math0008" num=""><math display="block"><mrow><msub><mrow><mtext>w</mtext></mrow><mrow><mtext>b</mtext></mrow></msub><mtext>=</mtext><msub><mrow><mtext mathvariant="italic">k</mtext></mrow><mrow><mtext mathvariant="italic">b</mtext></mrow></msub><mfrac><mrow><msub><mrow><mtext mathvariant="italic">t</mtext></mrow><mrow><mtext mathvariant="italic">sp</mtext></mrow></msub></mrow><mrow><mtext mathvariant="italic">r</mtext></mrow></mfrac></mrow></math><img file="EP1111359B1_D0008.tif" /></maths> where k_b is the coefficient of the specific arc resistance.

For the determination of the sheet resistance F_wb is based on the relationship:<maths id="math0009" num=""><img file="EP1111359B1_D0009.tif" /></maths> where the coefficient K is the existing gauge t_sp considered. According to known relationship applies to a gauge t_sp = 1435 mm,<ul id="ul0002" list-style="none" compact="compact"><li>for arc radii r ≥300 m F_wb = <maths id="math0010" num=""><math display="inline"><mrow><mfrac><mrow><mtext>650 </mtext></mrow><mrow><mtext mathvariant="italic">r</mtext><mtext>-50 </mtext></mrow></mfrac></mrow></math><img file="EP1111359B1_D0010.tif" /></maths></li><li>and radius of curvature r &lt;300 m F_wb = <maths id="math0011" num=""><math display="inline"><mrow><mfrac><mrow><mtext>500</mtext></mrow><mrow><mtext mathvariant="italic">r</mtext><mtext>-30</mtext></mrow></mfrac></mrow></math><img file="EP1111359B1_D0011.tif" /></maths></li></ul>

At arc radii r ≥ 300 m, the circuit component 52 and at arc radii r &lt;300 m, the circuit component 54 (Figure 2) of the detection and evaluation unit 26 is activated. A signal corresponding to the radius of curvature r is present at the input 38, which, as will be explained later, is provided by the inertial measuring system 22.

The circuit component 50 (FIG. 2) of the detection and evaluation unit 26 serves for the determination 45 of the running resistance F._wl, The running resistance F_wl is composed of the rolling resistance of the wheels on the guideway 14, the frictional resistance of the bearings and rotating drive components, and the air resistance of the system 10. The running resistance F_wl is always positive. The running resistance F_wl settles for the general relationship<maths id="math0012" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">w</mtext></mrow><mrow><mtext mathvariant="italic">l</mtext></mrow></msub><mtext> =</mtext><msub><mrow><mtext mathvariant="italic">c</mtext></mrow><mrow><mtext>0</mtext></mrow></msub><mtext> + </mtext><msub><mrow><mtext mathvariant="italic">c</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>· </mtext><mtext mathvariant="italic">v</mtext><mtext> + </mtext><msub><mrow><mtext mathvariant="italic">c</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><mtext> · </mtext><msup><mrow><mtext mathvariant="italic">v</mtext></mrow><mrow><mtext>2</mtext></mrow></msup></mrow></math><img file="EP1111359B1_D0012.tif" /></maths> determine. The coefficient c₀ indicates the speed independent portion. This primarily takes into account the rolling friction between the wheel and the rail, the bearing and the spring friction, the friction of the rotating drive parts and the influence of rail joints or the like. This constant proportion is thus largely dependent on the type and condition of the system 10 and the quality of the route 14. By the coefficient C₁ of the linear member (C₁ V) the motion-inhibiting influence of air currents is taken into account. The coefficient C2 takes into account the air resistance (arerodynamic resistance) of the system 10, which is proportional to the square of the velocity v.

The numerical values ​​of the coefficients C₀, C₁ and C₂ are known for known systems 10 and are obtained, for example, during test drives. These coefficients C₀, C₁ and C₂ can be stored in a table and, depending on the type of vehicles used 12 of the system 10 in consideration of the driving resistance F_v be retrieved.

In a system 10 having a plurality of vehicles 12, an average of the coefficients of the individual vehicles 12 may be formed for simplicity.

The running resistance F_wl individual vehicles 12 or a system 10 can be determined, for example, by a so-called run-out test, in which the system 10 or a vehicle 12 is driven without drive over a defined route. In accordance with the effects of friction, the air currents and the aerodynamic resistance, this results in a deceleration of the rolling system 10 or of the vehicles 12, ie a negative acceleration, via which the running resistance F_wl can be determined.

In the intended use of the system 10 is the for determining the running resistance F_wl required speed v as a signal at the input 34 and is provided - as will be explained - by the speed measuring device 24.

About the circuit components 44, 46, 48, in conjunction with the circuit components 52 and 54 and the circuit component 50, the individual driving resistors F_wa, F_wn, F_wb and F_wl determined and supplied to the formed as summing circuit component 56. This forms the sum and thus the total driving resistance F_w of the system 10. According to the already described relationship tensile force F to is equal to the negative driving resistance F_w can now on the circuit component 58, the instantaneous tensile force F_to of the system 10 are determined. The instantaneous tensile force F_to can be stored and / or displayed, for example, on a display screen in their time course.

For the determination of the individual driving resistances and thus of the total driving resistance F_w of the system 10 are the acceleration a_x in the direction of travel 16, the inclination angle β, the radius of curvature r and the instantaneous speed v required. These measured quantities must be measured in real time - to determine the instantaneous total driving resistance F_w and thus the instantaneous tensile force F_to to be provided. For this purpose, the inertial measuring system 22 and the speed measuring device 24 is provided.

The running resistance F_wl is speed-dependent, so that at the input 34, the instantaneous speed signal v must be provided. This is determined by the speed measuring device 24, for example, by detecting the ground speed. The driving speed v can be detected, for example, with an incremental encoder on a passive wheel set 18, that is, on a non-drivable and non-brakable wheelset 18. In this case, 18 pulses are generated with each revolution of the wheelset, so that it is possible to determine the speed v in a simple manner with a known extent and measured frequency of the pulses of the incremental encoder. If no passive wheelsets 18 are present in the system 10, for example in magnetic levitation trains, the actual speed can also be determined by means of other known methods, for example satellite-based methods (GPS) or radar measuring methods. For carrying out the method according to the invention, it is crucial that the actual speed v is provided as a signal. In addition to the determination of the running resistance F_wl can from the speed signal v by differentiation, the acceleration a_x of the system 10 in the direction of travel 16 are determined. According to a further embodiment variant, the acceleration a can be provided_x to detect by a separate, also known per se acceleration sensor. In addition, the detection of the distance traveled over the speed v is possible, which is necessary for the separate detection of the driving resistance of the individual vehicles.

However, on gradients or gradients of the route 14, additional acceleration due to gravity occur which can not be eliminated by an acceleration sensor acting only in the direction of travel 16 or from the speed signal v.

In order to determine the relevant path data, such as, for example, the gradient β and the radius of curvature r, the inertial measuring system 22 has a known gyro arrangement with which the accelerations in all three spatial directions and the rotation rates around all spatial axes can be measured. By knowing the acceleration in all three spatial directions, the useful acceleration component of the system 10 in the direction of travel 16 can be determined exactly. The radius of curvature r can thus be determined from the speed v and the rate of rotation about the system vertical axis. A determination of the inclination and the increase of bows is possible from the rotation rates around the system longitudinal axis and the system transverse axis.

The function and construction of such centrifugal principle-based inertial measuring systems 22 are known, so that it should not be discussed in detail in the context of the present description. It is crucial that with such inertial measuring systems 22 accelerations, rotation rates and the position angles of a moving body, here the moving system 10, can be determined.

The inertial measuring system 22 is arranged at a defined location of the system 10. This ensures that this system is fixed, so that the inertial measuring system 22 is subjected to the same dynamic influences as the system 10.

Hereinafter, the method for determining the tensile force F is based on the figures 3, 4 and 5_to with reference to a concrete example, which is shown schematically in Figure 6, to be clarified.

FIG. 6 schematically shows a train 10 which can be moved along the route 14 by a traction vehicle 112 designed as an electric locomotive. By means of the device 20, the tensile force F_to of the traction vehicle 112, which exerts this on the train 10. The train 10 comprises in addition to the traction vehicle 112 a measuring carriage 114, a support vehicle 116 and a brake drive vehicle 118. The traction unit 112 is coupled to the measuring carriage 114 via a known Zugkraftmeßkupplung 120. This Zugkraftmeßkupplung 120 is used only for the verification of the delivered by the device 20 instantaneous values ​​of the tensile force F._to, During an actual test drive can be dispensed with the arrangement of Zugkraftmeßkupplung 120. The brake truck 118 is connected to the backing carriage 116 via a brake power hook 122. The brake truck 118 is for simulating the load of a train of a plurality of vehicles 12 (FIG. 1). If the brake drive vehicle 118 is pulled along by the traction vehicle 112, a braking torque acts. The resulting additional braking force is detected by the Bremszugkrafthaken 122 and in the determination of the acceleration resistance F_wa considered by addition.

By the device 20 - as explained - the acceleration resistance F_wa, the slope resistance F_wn, the bow resistance F_wb and the running resistance F_wl, determined. The sum, ie the total travel resistance F_w the determined individual driving resistances, provides the tensile force F_to on the wheel circumference of all drive wheels of the locomotive 112.

In Figure 3, two traction characteristics are shown, wherein the tensile force F_to is registered over the speed v. A first tensile force characteristic 60 shows the course of the tensile force F determined by means of the device 20_to, A second characteristic 62 shows the course of the tensile force F_to, which was determined only for verification purposes by means of Zugkraftmeßkupplung 120. With reference to the substantially congruent course of the characteristics 60 and 62 it is clear that by the device 20 and carried out by means of the device 20 method for determining the tensile force F_to very exact values ​​can be provided. These are provided without, as in the Zugkraftmeßkupplung 120, a direct tensile force measurement.

FIG. 4 shows the course of the individual driving resistances over the speed v for clarification. Here are the left brake force F_br and the damage resistance F_wa and on the right the inclination resistance F_wn, the bow resistance F_wb as well as the running resistance F_wl scaled.

A characteristic curve 64 illustrates the course of the braking force F._brtaking into account the load simulated via the brake truck 118. A characteristic curve 66 shows the course of the acceleration resistance F_wa, which takes into account the force component required for the mass acceleration of the train 10. A characteristic 68 represents the course of the inclination resistance F_wn taking account of slopes and gradients of the route 14. A characteristic curve 70 shows the course of the sheet resistance F_wb In the case of the test drive documented here, it is a route 14 without bends, so that the characteristic curve 70 runs essentially on the zero line. Finally, curve 72 is entered, the course of the running resistance F_wl features. It becomes clear that with increasing speed v the running resistance F_wl increases exponentially.

In FIG. 5, the inclination resistance F is_wn shown over the distance s of the route 14. A first characteristic 74 represents the course of the inclination resistances F measured by the device 20_wn while a second characteristic curve 76 represents for comparison the slope of the route 14 taken from a known route file. It will be apparent that the measured pitch resistance F_wn substantially coincident coincides with the actual slope course of the route 14. This results in a further advantage that a route file of routes 14, which can be created only very expensive, for the determination of the inclination resistance F_wn in itself is not needed. Furthermore, by means of the instantaneous measurement of the inclination resistance F_wn a more accurate measurement possible, since here the actual current track conditions are taken into account, which may differ from calculated expected track conditions, which are stored in a track file.