DE19519768A1 - Braking power adjustment method for trailer of vehicle-trailer combination - Google Patents

Abstract

The method involves a tractor vehicle and at least one trailer. Initially, multiple actual values of variables characterising braking behaviour of the trailer are determined, these variables being for a multiple of braking requirements controlled at the tractor vehicle. A first braking curve is determined from the multiple of actual values of the variable characterising the braking behaviour of the trailer. A desired braking curve (Zsoll,Zsoll1,Zsoll2) is then determined. A correction value is determined for the braking requirement of the trailer, as the difference between the desired and the actual braking curve (Zist). The braking requirement of the tractor vehicle is thus altered according to the correction value, and the corrected braking requirement of the trailer is controlled.

Description

The invention relates to a method and a front direction for adjusting the braking force of a trailer one from a towing vehicle and at least one trailer existing vehicle group according to the preamble of Claim 1 or claim 13.

It is known that the braking force between a towing vehicle and a trailer depending on the loading of the Trailer is adjusted to improve braking to maintain and the coupling forces on the towbar not to let it get too big. For this purpose, was earlier a switch on the trailer (this also applies to railroad cars) valve operated by hand when the load has been changed.

US Pat. No. 5,002,343 shows an electronic braking system for a semi-trailer truck. On the front and rear axles of the towing vehicle are load sensors and on the coupling  of the towing vehicle and trailer is a coupling force sensor intended. The coupling force sensor measures the tension and pressure force exerted by the trailer on the towing vehicle. Out of this the entire tensile mass is accelerated with the help the coupling force determined. According to the determined The trailer or semi-trailer mass then applies the braking force division between towing vehicle and trailer.

In DE 40 35 805 C1, the coupling force is also measured between towing vehicle and trailer and by Vari ation of the braking pressure of the trailer to a predetermined Setpoint brought. The required brake pressure of the trailer gers in a previous braking operation in which the coupling force is equal to its setpoint, taking into account the brake pressure of the towing vehicle.

DE 42 20 991 A1 uses a sensor to measure whether the pressure force in the direction of travel between the trailer and Towing vehicle exceeds a certain threshold, then the braking force distribution from a microcomputer between the towing vehicle and trailer.

DE 41 30 848 C1 describes a method for brake pressure regulation for a trailer without a coupling force sensor is needed. Only the wheel speed will be there on the towing vehicle and the trailer. The brake force distribution between towing vehicle and trailer set so that the average rotational speed of the Wheels of non-driven axles of both parts of the vehicle Chen are. The trailer brake pressure is based on one the specified starting value is updated accordingly.

EP 0 621 161 A1 describes a method for determining the impact force of a trailer, in which the between Towing vehicle and trailer acting forces without use can be determined by load sensors.  

The older, unpublished German patent applications Messages P 44 12 430 and P 44 46 358.8 describe closing Lich a procedure for adjusting the braking force distribution between a towing vehicle and a trailer where the total energy of the vehicle group to three different ones Points in time from measured and vehicle-specific quantities corresponding stored values is determined. Out of this the vehicle mass and the slope angle determine and the braking force distribution between towing vehicle and adjust trailers. In the latter P 44 46 358.8 the measurements are only carried out if the vehicle is in the non-driven state and the brake is not applied.

In general, it can be said that when braking a The driver's vehicle network via the brake pedal Demand signal generated from which for the towing vehicle and the trailer generates a brake pressure to be controlled becomes. The brake pressure that is applied to the towing vehicle is different from the brake pressure on the trailer, it being basic goal is to link the coupling forces between Towing vehicle and trailer within specified limits to keep and this even with different loading stands of the trailer.

However, in the prior art described above at best indirectly takes into account that different followers have very different braking characteristics. Under Braking characteristic is the braking force depending on controlled brake pressure understood. As with the stand technology - the brake pressure of the trailer depending the coupling force between trailer and towing vehicle applies, the braking characteristic becomes indirect of the trailer is taken into account, but one is required certain period of time before the regulation the "right" brake pressure in the trailer, depending on the type of the controller used also for transients or Overshoots can come.

The object of the present invention is to process and Devices of the type mentioned above further to form that the brake pressure of the trailer depending from the braking request for the entire vehicle network is optimally controlled as quickly as possible.

This task is for the process by the patent Claim 1 and for the device by the in Patentan verse 13 specified features solved.

Advantageous refinement and developments of the invention can be found in the subclaims.

The basic idea of the invention is the braking characteristic, d. H. Braking force depending on the braking pressure of the trailer determined by several measurements and the following Braking processes to regulate the braking pressure of the trailer that based on the determined braking characteristic of the appendix gers a freely definable target characteristic of the trailer is achieved. In other words, the towing vehicle seen from the trailer any desired "target" - Braking characteristic forced. Seen from the towing vehicle has any trailer regardless of his braking properties inherently present always the same clearly defined braking characteristic. For every braking requirement driver's signal can be used to create a clear, Brake pressure adapted to the braking characteristic of the towing vehicle Predetermine for the trailer, which then without regulation gear can be controlled immediately on the trailer.

The target braking characteristic of the trailer can be released after one predefinable function can be specified. According to a variant the invention is the braking characteristic of the trailer determines that it is equal to the braking characteristic of the towing vehicle is, with which all axles of the vehicle group braked equally will. This is done through the relationship

where F _{h is} the horizontal coupling force F _{v is} the vertical coupling force, a is vehicle acceleration and g is acceleration due to gravity.

According to another variant of the invention, the characteristic curve of the trailer so that they are centered in a pre given compatibility band.

A large is used to determine the actual braking characteristic Number of measured values that can scatter extremely a straight line using the method of least squares educated. This straight line is then used as the actual characteristic curve of the trailer viewed and freely specified after the mentioned baren function adjusted according to the above criteria.

Since the individual measured values for the actual braking characteristic of the trailer vary widely in practice, which is caused, for example, by uneven road surfaces, the braking characteristic assumed as a straight line can deviate greatly from the actual values in individual cases. In order to avoid over-braking the trailer, a further development of the inven tion provides that certain limit conditions are to be observed for the determination of the target braking characteristic from the actual braking characteristic present as a straight line. These boundary conditions are:
The maximum brake pressure in the trailer is limited to a predetermined value (for example 7 bar);
the maximum pressure increase of the brake pressure for the trailer compared to the brake pressure of the towing vehicle is limited to a predetermined value (for example 2) bar.

The measurement of the individual points of the actual characteristic curve can in any manner, for example also by means of Sensors such as coupling force sensors on the trailer coupling, Load sensors for determining the mass of the trailer Etc.

Basically, the braking characteristic of a trailer is through  determines the following relationship:

where Z _is the actual value of the deceleration
F _AH the braking force between the road surface and the trailer wheels;
F _{A is} the axle load of the trailer acting perpendicular to the road;
m _{A is} the mass of the trailer;
a the acceleration of the vehicle network;
F _{KH is} the horizontal coupling force on the trailer coupling;
F _{WID was} the force from the sum of rolling resistance and air resistance;
g gravitational acceleration;
α the slope between the road and a horizontal plane;
l _{K is} the distance between the kingpin of the towbar and the center axle of the trailer; and
l _{CG is} the distance between the center of gravity of the trailer and the center axis of the trailer.

The sizes F _WID ; l _K and l _CG are vehicle-specific values that are entered by the manufacturer as fixed values. The acceleration due to gravity g is also a constant, known quantity. The mass of the trailer m _A is available as a measured value in modern vehicles with air suspension. However, it can also be determined together with the slope angle according to the older, not previously published German patent applications P 44 12 430.9 or P 44 46 358.8 by the following steps:

• - measuring the vehicle speed (v),
• - Measure one with the drive energy of the towing vehicle  linked size (Md) and
• - Measure a quantity associated with the braking energy (p) at three different times (t₀, t₁, t₂),
• - Determine the total energy (E₀, E₁, E₂) of the vehicle network at these three times (t₀, t₁, t₂) from the measured values and corresponding values from vehicle-specific quantities, this being determined according to the following relationship: E = E _antr + E _kin + E _pot - E _roll - E _vw - E _br , where
• - E the total energy of the vehicle group,
• - E _antr the drive energy as a function of the quantity (Md) linked to the drive energy,
• - E _{kin is} the kinetic energy of the vehicle network as a function of mass (m) and speed (m / 2 _* v²),
• E _pot the potential energy as a function of mass (m), distance covered (s) and slope angle (a) according to the relationship m _* g _* s _* sin (α),
• - E _roll energy losses as a function of mass, gravitational acceleration and a constant,
• - E _vw the wind resistance _losses as a function of the wind resistance coefficient and the speed and
• - E _{br are} the braking energy losses as a function of the vehicle speed (v) and the quantity associated with the braking energy (p),
• - Determine the vehicle mass (m) and the slope angle (α) from the determined energy values (E₀, E₁, E₂), two of which each ver three different times (t₀, t₁, t₂) determined energy values (E₀, E₁, E₂) are assumed to be the same size (E₀ = E₁, E₀ = E₂).

The total energy (E₀) is preferably the first of the three named measuring times (t₀) equal to the kinetic Energy of the vehicle network set, while all others Partial energies are set to zero.

A further training is that the three mentioned Measuring times (t₀, t₁, t₂) at equidistant time intervals to each other that at all three measuring times the Slope angle is assumed to be constant and that the energy (E₀) equal to the energy at the first time of measurement (E₁) to the second and equal to the energy (E₂) to the third Measurement time is set, from which the vehicle mass (m) and the downhill slope angle (α) is determined.

The vehicle acceleration a (which assumes negative values when braking) is provided by the anti-lock device in the towing vehicle as a "measured value". The coupling force F _KH can also be derived in accordance with the method known from the prior art (EP 0 621 161 A1) from measured values already present in the vehicle network without the need for special coupling force sensors.

An important advantage of the invention is that Forces that only act on the towing vehicle, e.g. B. Wind forces or a retarder does not affect the determination of the Have the characteristic of the trailer.

If you have, as described above, the actual braking characteristic of the Trailer determined, so when modifying the Er checked with the compatibility band whether this actual Characteristic lies in this compatibility band. Is this the case, it is a well braked trailer; Corrections are then not necessary. With one bad braked trailer is the one controlled in the trailer Brake pressure increased until you reach the corresponding one Braking requirement is within the compatibility band, but with the above-mentioned boundary conditions are to be observed.  

With the invention you get the possibility, also very much badly braked trailer with a very flat Brake characteristic with a well braked towing vehicle couple and still also for the trailer each to be able to control the optimal braking force.

In the following the invention in connection with the Drawing explained in detail. It shows

Figure 1 is a schematic diagram of a vehicle group on an incline to explain the various terms.

Fig. 2 is a graph of the braking function of the brake pressure for two different trailer;

FIG. 3 shows various graphs of pressure gradients and Abbremsungsverläufen according to the invention; and

Fig. 4 is a block diagram of a device according to the invention.

First, reference is made to FIG. 1:
With a trailer such as B. the semi-trailer of a semitrailer results in a loading condition by a trailer control pressure P _anh a braking force F _AH and an axle load F _A acting perpendicular to the road. The current deceleration Z of the trailer is thus

For the results shown in Fig. 1 trainset comprising a tractor 1 and a semitrailer 2 which are interconnected via a trailer coupling 3 and in which the distance between the king pin of the hitch 3 and the central axis 5 of the semitrailer 2 the value of l _k and the distance between the center of gravity 4 of the trailer 2 and the central axis 5 of the trailer 2 has the value l _CG and the slope α between the road 6 and a horizontal plane 7 is known and finally the mass of the trailer is m _A , results for the current deceleration Z _is from the condition of the balance of the forces the relationship mentioned above:

where a and F _{KH are} functions of the brake pressure.

In general, the braking behavior of a trailer can be characterized by a diagram (see FIGS. 2 and 3), which represents the braking defined Z as a function of the trailer brake _pressure P _ANH (also referred to as trailer control pressure). This referred to here as the "braking characteristic" and sometimes referred to in the technical literature as the "braking ratio" is shown in Fig. 2 for a well braked trailer with the characteristic A1 and for a badly braked trailer with the characteristic A2. The characteristic curve A1 begins at the origin of the coordinates, ie there is a braking effect even at a very low trailer control pressure. In relation to characteristic curve A2, characteristic curve A1 also runs relatively steeply in accordance with a linear function. The characteristic curve A2 of the "badly" braked trailer, on the other hand, runs significantly flatter and shows a "dead" area in which, despite the trailer control pressure already present, no braking effect can be determined.

The two lines shown in dashed lines B _k1 and B _k2 include between them a "compatibility _band " B _K , within which the braking characteristic of the trailer should lie so that the towing vehicle and trailer are compatible with each other with regard to the braking effect, which is equivalent to the fact that the coupling forces remain within specified limits between the towing vehicle and the trailer. This compatibility band is determined by the braking characteristic of the towing vehicle, the braking characteristic of the towing vehicle generally being in the middle of the compatibility band. In the invention, however, it is also possible to determine the compatibility band according to any other function that can be freely specified. This allows the trailer to be assigned any braking characteristic. For example, it is also possible to determine the braking characteristic of the trailer so that the absolute value of the thrust forces on the trailer coupling deviates from the maximum possible absolute value of the tractive forces on the trailer coupling. In this case, the compatibility band would be placed asymmetrically to the braking characteristic of the towing vehicle. The compatibility band also need not, as shown in Fig. 2, be defined by a straight line. Any functions, ie curved lines, can be specified. It is also possible to change the "width" of the compatibility band depending on the pressure, for example in such a way that the compatibility band is relatively wide at small brake pressures and narrow at large brake pressures. It is also possible to make the compatibility band dependent on further parameters, for example on the vehicle speed, the vehicle deceleration or the mass of the vehicle group. For example, the compatibility band could be wider at low speeds than at higher speeds.

Fig. 3a shows the braking pressure of the trailer p _A in dependence on the brake pressure of the towing vehicle p _Z in a vehicle without the present invention. The two pressures are identical, ie the same size; the corresponding characteristic curve therefore runs at an angle of 45 ° to the two main axes.

In Fig. 3b, the deceleration Z _{A of} the trailer as a function of the brake pressure of the towing vehicle p _Z , which is equal to the pressure p _{A of} the trailer without the invention, is represented by a solid line. The "compatibility band" B _K is shown with double hatching. As long as the braking characteristic lies within this compatibility band B _K , it can be assumed that the braking characteristic of the trailer and that of the towing vehicle match each other with sufficient accuracy. For the brake characteristic line shown in Fig. 3b of a trailer, this is only given in the lower, but not in the upper pressure range. At higher braking pressures for the towing vehicle and trailer, the trailer would therefore brake too weakly in relation to the towing vehicle with the known negative consequences, starting with excessive wear on the brakes of the towing vehicle to instability of the entire vehicle network and kinking of the towing vehicle in relation to the Longitudinal axis of the trailer.

With the method according to the invention ( Fig. 3c and d), the braking characteristic Z _{ist of} the trailer is determined from a large number of measured values. According to a variant of the invention, a straight line is formed from the plurality of determined values for Z _is by the method of the sum of the smallest error squares, which is regarded as the actual characteristic curve Z _is the braking. Then it is checked with a specific braking request P ₁ whether the associated value Z _{ist1 of} this characteristic lies within the compatibility band B _K. If this is the case, the same brake pressure is applied in the towing vehicle and in the trailer. If, on the other hand, this is not the case, ie Z _ist1 lies outside the compatibility band B _K , the brake pressure p _A for the trailer is changed compared to the brake pressure p _Z for the towing vehicle, ie increased by delta p2 ( FIG. 3d) in the example shown, so that the braking behavior of the trailer is improved by the amount delta Z2 according to FIG. 3c, with the result that the braking behavior of the trailer follows the characteristic curve Z _soll2 . In the case of a trailer braking "better" in relation to the towing vehicle (which in practice is seldom used in practice), the braking pressure of the trailer is lowered until it lies within the compatibility band B _K.

In Fig. 3c it can be seen that the desired curve _will be Z splits for deceleration from a certain brake pressure in two curves Z _set1 and _set2 Z. The curve Z _set1 runs approximately parallel to the upper limit B of the compatibility _{K1 K} band B, while curve Z _soll2 braking curve parallel to the actual From Z _is running. Depending on whether the braking curve of the trailer is raised to the curve Z _soll2 or Z _soll1 , there is a corresponding pressure increase of the trailer control pressure via the towing vehicle control pressure corresponding to the pressure increase delta P2 or delta P1 according to FIG. 3d, which increases the braking characteristic delta Z2 or delta Z1 in Fig. 3c corresponds.

According to a development of the invention, the brake characteristic line of the trailer is only "raised" up to curve Z _soll2 , ie the increase in the brake pressure of the trailer control pressure is limited to a predetermined maximum value delta P2, which has a value of 2 bar, for example.

This is based on the following considerations:
The measured values, from which the linear function Z _{is formed} according to FIG. 3c, scatter very strongly in practice, which is due to a substantial proportion of bumps in the road, partly due to measurement errors, partly due to digitization or rounding errors when evaluating the measurement results , but also partly due to fluctuations in the brake characteristics of the individual brake. The definition of the braking characteristic as a straight line Z _is therefore a very useful in practice, but is nevertheless not always an approximation corresponding to the real conditions. For example, in an extreme case with the brake pressure p1 of FIG. 3c, the actual braking can be Z1 and therefore within of the compatibility band B _K , while the linear characteristic Z _ist results in the much smaller value Z _ist1 . In such a case, if one increased the braking characteristic by the amount delta Z₁ to get from Z _ist1 to a value Z₄ on the target characteristic Z _soll1 , one would actually reach the value Z₅ from Z₁, which is clearly above the Kompati balance band B _K1 lies. The trailer would be braked massively. For this reason, the increase in the characteristic curve is limited to the value delta P2, so that even if the value Z₁ is the actually existing deceleration value, an increase by delta Z₂ only leads to the value Z₃, which lies within the compatibility band B _K.

As a further measure of a similar type, it is provided that the maximum value of the brake pressure for the trailer is limited to a predetermined value of, for example, 7 bar. If the braking pressure of the towing vehicle exceeds 5 bar in this example, the braking pressure of the trailer is no longer increased by the maximum amount of delta p2 (2 bar), but only to the limited absolute value of 7 bar. This also prevents the trailer from overbraking due to deviations between the actual braking and the idealized braking characteristic Z _is prevented.

Fig. 2 shows in a similar representation as Fig. 3c, the braking characteristics of a well-braked trailer A1 and a badly braked trailer A2. With the exception of a small lower pressure range, the characteristic curve A1 lies within the compatibility band. A correction is not necessary. The characteristic curve A2, on the other hand, is predominantly outside the compatibility band. At a brake pressure p6, this results in a deceleration Z₆ which is below the compatibility band B _K. In order to reach a deceleration value Z₇ that lies within the compatibility band B _K , the brake pressure of the trailer must be increased by the amount delta p to the value p₇, which then achieves the deceleration Z₇ that lies within the compatibility band B _K. In this case, the pressure p₆ is activated on the towing vehicle, while the pressure p₇ is activated on the trailer, in order to obtain a deceleration compatible with the towing vehicle for the trailer.

Fig. 4 shows a block diagram of a device according to the invention.

The towing vehicle is represented by a block 11 and the trailer by a block 12 . The towing vehicle contains a brake valve 13 and at least one sensor 14 , which is here a speed sensor that generates an electrical signal proportional to the speed of rotation of a monitored wheel. Depending on the brake system of the towing vehicle, each wheel can have its own sensor; With some brake systems, it can also be sufficient if only each axis has a sensor.

Similarly, the trailer 12 has at least one brake valve 15 and at least one sensor 16 . A braking process is initiated by a braking request 17 , for example by pressing a brake pedal in the towing vehicle. This braking request is converted into an electrical signal and fed to a control unit 18 . The centerpiece of the control unit is a microprocessor 19 , which, in addition to the braking request, also contains electrical signals from an engine control 20 (Electronic Diesel Control), an anti-lock device 21 , a vehicle-specific value for the air resistance 22 and a vehicle-specific, stored value 23 for the mass of the towing vehicle be fed.

From these supplied values, the microprocessor 19 determines a target value for the brake pressure of the towing vehicle, which is supplied to the brake valve 13 via a controller 24 .

Furthermore, the microprocessor 19 uses the braking request 17 to determine a target value for the braking pressure of the trailer, which is supplied to the brake valve 15 of the trailer 12 via a controller 25 . This value for the desired brake pressure of the trailer is determined in accordance with the method described above, the braking characteristic of the trailer and the further parameters such as, for. B. Functions for modifying this characteristic are stored in a memory 26 connected to the microprocessor 19 . These parameters can be, for example, values for the compatibility band described above and also the limit values for the pressure increase or a limit value for the maximum brake pressure to be supplied to the trailer.

The actual braking pressure supplied to the towing vehicle or the trailer is determined via measuring members 27 and 28 and leads to the microprocessor 19 or the regulators 24 and 25, respectively. These measuring elements 27 and 28 can be pressure cells; but it is preferably also possible to determine the pressures in another known manner, for example by measuring the opening and closing times of valves.

Of course, the vehicle-specific values of the assemblies 22 and 23 can also be stored in the memory 26 . In addition, the anti-lock function can also be performed by the microprocessor 19 .

During each braking, actual values for the braking Z _{ist of} the trailer are determined from measured, derived and stored values and stored in the memory 26 . From a large number of such individual "measured values" of the braking, the braking characteristic Z _A of FIG. 3b or Z _{is then determined} according to FIG. 3c by the microprocessor 19 , which is preferably carried out using the method of the least squares of errors. The more "measured values" there are, the more precisely the braking characteristic Z _is adapted to the actual braking behavior of the trailer. This characteristic curve is therefore recalculated several times, which can be done according to various criteria. On the one hand, the characteristic curve is redetermined at the start of a journey. The start of a journey can be detected, for example, by actuating the ignition key. Furthermore, the recalculation of the characteristic curve can always be triggered when a predetermined number of new "measured values" has been recorded. This number can be set as desired and can also have the value 1 in extreme cases. It is also possible to always recalculate the characteristic curve after braking.

Once the characteristic curve has been determined, the next braking process to be controlled on the trailer brake pressure depending on the braking request and the characteristic modified so that the braking of the trailer desired and for compliance with the compatibility band necessary pressure corresponds. This will start with braking the braking pressure for the trailer on the "correct" value is preset and does not have to be replaced by a Control process can only be determined during braking.

With the invention, a "table" or characteristic curve can then ultimately be stored in the memory 26 , which contains the trailer brake pressure p _A as a function of the brake pressure of the train vehicle ges p _Z , so that each brake pressure for the towing vehicle has a unique brake pressure for the trailer assigned.

Claims (15)

1. Method for setting the braking force of a trailer of a vehicle group consisting of a towing vehicle and at least one trailer, with the following steps:

• - Determining a large number of actual values of a variable characterizing the braking behavior of the trailer for a large number of braking requests entered on the towing vehicle;
• Determining an actual braking characteristic from the plurality of actual values of the variables characterizing the braking pressure behavior of the trailer;
• - Setting a target braking characteristic of the trailer;
• - Determining a correction value for the braking request of the trailer as the difference between the target braking characteristic and the actual braking characteristic;
• - changing the braking request for the towing vehicle by the correction value; and
• - Activation of the corrected braking request on the trailer.

2. The method according to claim 1, characterized in that the braking behavior of the trailer characterizing size of the quotient of braking force (F _AH ) of the trailer and the axle load (F _A ) of the trailer. 3. The method according to claim 2, characterized in that the quotient of the braking force of the trailer and the axle load of the trailer is determined by the following relationship: in which

• - Z _is the actual braking value
• - F _AH the braking force between the road and the trailer wheels;
• - F _{A is} the axle load of the trailer acting perpendicular to the road;
• - m _{A is} the mass of the trailer;
• - a the acceleration of the vehicle network;
• - F _{KH is} the horizontal coupling force on the trailer coupling;
• - F _{WID is} the force from the sum of rolling resistance and air resistance;
• - g gravitational acceleration;
• - α the slope between the road and a horizontal plane;
• - l _{K is} the distance between the king pin of the trailer coupling and the central axle of the trailer; and
• - l _{CG is} the distance between the center of gravity of the trailer and the center axis of the trailer.

4. The method according to any one of claims 1 to 3, characterized characterized in that the actual braking characteristic from the Actual values of the braking behavior of the trailer characteristic size according to the method of least squares is determined. 5. The method according to any one of claims 1 to 4, characterized characterized in that the target braking characteristic of Trailer according to a freely definable function the actual braking characteristic of the trailer is formed. 6. The method according to any one of claims 1 to 5, characterized characterized that the target braking characteristic within a compatibility band lies, its limits to the braking characteristic of the towing vehicle have a predetermined distance.   7. The method according to any one of claims 1 to 6, characterized characterized in that the correction value for the Brake request of the trailer on a fixed predetermined maximum value is limited. 8. The method according to any one of claims 1 to 7, characterized characterized in that the correction value for the Braking request of the trailer is so limited that the maximum value of the trailer's braking request does not exceed a predetermined value. 9. The method according to any one of claims 1 to 8, characterized in that the values required for determining the size characterizing the braking behavior of the trailer, the mass of the trailer and the slope between the road and a horizontal plane are determined by the following steps:

• - measuring the vehicle speed (v),
• - Measuring a quantity (Md) linked to the drive energy of the towing vehicle
• - Measuring a quantity (p) linked to the braking energy at three different times (t₀, t₁, t₂),
• - Determine the total energy (E₀, E₁, E₂) of the vehicle network at these three times (t₀, t₁, t₂) from the measured values and corresponding values from vehicle-specific quantities, this being determined according to the following relationship: E = E _antr + E _kin + E _pot - E _roll - E _VW - E _br , where
• - E the total energy of the vehicle group,
• - E _antr the drive energy as a function of the quantity (Md) linked to the drive energy,
• - E _{kin is} the kinetic energy of the vehicle network as a function of mass (m) and speed (m / 2 _* v²),
• E _pot the potential energy as a function of mass (m), distance covered (s) and slope angle (α) according to the relationship m _* g _* s _* sin (α),
• - E _roll energy losses as a function of mass, gravitational acceleration and a constant,
• - E _VW the wind resistance losses as a function of the wind resistance coefficient and the speed and
• - E _{br are} the braking energy losses as a function of the vehicle speed (v) and the quantity associated with the braking energy (p),
• - Determining the vehicle mass (m) and the slope angle (α) from the determined energy values (E₀, E₁, E₂), with two of the energy values determined at three different times (t₀, t₁, t₂) (E₀, E₁, E₂) are assumed to be the same size (E₀ = E₁, E₀ = E₂).

10. The method according to claim 9, characterized in that the total energy (E₀) to the first of the three mentioned Measuring times (t₀) equal to the kinetic energy of the Vehicle network set, while all others Partial energies are set to zero. 11. The method according to claim 10, characterized in that the three times mentioned (t₀, t₁, t₂) in equidistant time intervals are that the slope angle at all three measuring times is assumed to be constant and that the energy (E₀) at the first time of measurement equal to the energy (E₁) second and equal to energy (E₂) for the third Measurement time is set, from which the vehicle mass (m) and the downhill slope angle (α) determined becomes. 12. The method according to any one of claims 1 to 8, characterized in that the values required for determining the size characterizing the braking behavior of the trailer of the mass of the trailer and the slope between the road and a horizontal plane are determined by the following steps:

• a₁) measuring the vehicle speed (v)
• a₂) determining a size (Gü) corresponding to the current gear ratio,
• a₃) determining a quantity corresponding to the current braking state (Br ′),
• a₄) Check with the aid of the size (Gü) corresponding to the current transmission ratio and the size (Br ′) corresponding to the current braking state that the vehicle is in the non-driven state and a brake is not applied,

over a period of time (T₀-T₂),

• a₅) determining the total energy (E₀, E₁, E₂) of the vehicle group at three different points in time (T₀, T₁, T₂), which lie within the stated time span (T₀-T₂) from the measured values and corresponding corresponding to vehicle-specific values,
• a₆) determining (1) the slope angle (α) from the determined energy values,
• b₁) measuring a variable associated with the driving force of the train driving vehicle (Md),
• b₂) measuring the vehicle speed (v),
• b₃) determining a quantity (Gü) corresponding to the current gear ratio,
• b₄) determining a quantity corresponding to the current braking state (Br ′),
• b₅) Check with the help of the size corresponding to the current gear ratio (Gü) and the size corresponding to the current braking state (Br ') that the vehicle is in the driven state and a brake is not applied

at one time (T₃),

• b₆) Determining (2) the mass of the vehicle group (m) with the help of the equilibrium of forces from the measured values measured and corresponding to vehicle-specific variables and the determined slope angle (α) and
• c) automatic adjustment of the braking force distribution between the towing vehicle and trailer depending on the mass of the vehicle group (m) determined in this way.

13. Device for adjusting the braking force of a trailer of a vehicle network consisting of a towing vehicle and at least one trailer, characterized by measuring and computing arrangements ( 14 , 16 , 17 , 20 ,, 21 , 22 , 23 , 19 ), which are measured and stored Sizes a size characterizing the braking behavior of the trailer (Z _ist ) for a large number of braking requests activated on the towing vehicle ( 11 ) determines that the computing unit ( 19 ) derives an actual braking characteristic from the large number of actual values which characterize the braking behavior of the trailer determined sizes, and stores them in a memory (26), that the arithmetic unit (19) _(to Z), a target Abbremskennlinie of the trailer (12) sets; that the arithmetic unit ( 19 ) determines correction values (delta p) for the braking request of the trailer ( 12 ) from the difference between the target braking characteristic (Z _soll ) and the actual braking characteristic (Z _ist ) and a signal for a braking request of the trailer Brake control valve ( 15 ) of the trailer ( 12 ) controls which corresponds to the brake request for the towing vehicle ( 11 ) which has been changed by the correction value.