Method for operating a safety system for a vehicle combination, safety system, trailer vehicle and vehicle combination

Abstract

Method for operating a safety system (4) for a vehicle combination (1) comprising a towing vehicle (2) and a trailer vehicle (3) coupled together, and a trailer-side drive unit (25) providing a drive torque (24, 37, 38) independent of the towing vehicle (2), wherein an articulation angle (ĸ) of the vehicle combination (1) between the towing vehicle (2) and the trailer vehicle (3) is detected by means of an angle detection unit (27) and provided to the trailer-side drive unit (25), which controls the trailer vehicle (3) based on the articulation angle (ĸ), wherein, based on the articulation angle (ĸ), the trailer-side drive unit (25) applies an additional braking torque (32) to an inside wheel (19) of the trailer vehicle (3) and simultaneously applies an additional driving torque (33) to an outside wheel (20) of the trailer vehicle (3). is characterized by the fact that it is subject to pressure,that to determine the articulation angle (ĸ) of the vehicle combination (1), a curve curvature of the towing vehicle (2) is determined, which is a quotient of a yaw rate and a travel speed of the towing vehicle (2), and a curve curvature of the trailer vehicle (3) is determined, which is a quotient of a yaw rate and a travel speed of the trailer vehicle (3).

Description

[0001] According to claim 1, the invention relates to a method for operating a safety system for a vehicle combination. Furthermore, according to claim 4, the invention relates to a safety system for a vehicle combination. According to claim 5, the invention further relates to a trailer vehicle. Finally, according to claim 9, the invention relates to a vehicle combination comprising a towing vehicle and a trailer vehicle.

[0002] In vehicle combinations known from the prior art, in which a towing vehicle and at least one trailer vehicle are coupled together by means of a coupling device, a driving state of the vehicle combination is characterized, among other things, by a kink angle of the vehicle combination between the towing vehicle and the trailer vehicle. For example, when the vehicle combination is braked, in particular by the towing vehicle, it can happen that the trailer vehicle presses or pushes forward against the towing vehicle, so that the kink angle becomes unintentionally excessive. In particular when the vehicle combination is cornering, the problem then arises that as the kink angle between the towing vehicle and the trailer vehicle increases, there is an ever-increasing risk that the trailer vehicle will press so hard against the towing vehicle that the kink angle increases quickly and uncontrollably, like a folding pocket knife.This is also known as “jack-knifing” and represents a particularly high risk for a semi-trailer truck, as the cab of the tractor unit can be hit by the semi-trailer from the tractor unit chassis and ultimately sheared off.

[0003] In some situations, the trailer combination may also be more likely to collapse or collapse if it includes a trailer-side drive unit that provides drive torque independent of the towing vehicle. This further increases the tendency of the trailer to push or slide toward the towing vehicle, making the correspondingly equipped vehicle combination more prone to collapse or collapse.

[0004] There is therefore a need to prevent an uncontrolled or uncontrollable increase or growth of the articulation angle of the vehicle combination. For this purpose, DE 10 2010 031 158 A1 and DE 35 35 225 A1, for example, propose reducing the drive torque provided in / by the trailer vehicle independently of the towing vehicle, at least when there is a risk of buckling or collapsing of the correspondingly equipped conventional vehicle combination.

[0005] Furthermore, DE 10 2010 062 979 A1 discloses a push trailer with a drive unit designed to control or drive wheels of the push trailer individually. Furthermore, the push trailer has a sensor system by means of which, in particular, a yaw rate of the push trailer can be detected. Furthermore, the push trailer can comprise a system for detecting an articulation angle between the push trailer and a vehicle coupled thereto, whereby the drive unit of the push trailer can be controlled in such a way that stable driving behavior of the vehicle combination is achieved. In particular, it is provided that, based on the detected yaw rate, a wheel-specific control of the individual wheels of an axle of the push trailer generates a yaw moment in order to dampen a yaw oscillation of the vehicle combination and ultimately return the vehicle combination to a safe driving state.

[0006] US 2008 / 0 169 144 A1 shows a combination consisting of a tow truck and a towed vehicle. A sensor determines the tilt angle of the combination, and individual wheels of the towed vehicle can be controlled individually to stabilize the combination. For example, when cornering, an outside wheel can be driven more strongly than an inside wheel.

[0007] DE 10 2020 200 022 A1 discloses a method for determining the articulation angle of a vehicle combination between a towing vehicle of the vehicle combination and a trailer of the vehicle combination coupled to the towing vehicle by means of a coupling device, wherein the trailer has a drive force independent of the towing vehicle. The object of the present invention is to further increase road safety.

[0008] This object is achieved by a method having the features specified in patent claim 1, by a safety system having the features specified in patent claim 4, by a trailer vehicle having the features specified in patent claim 5 and by a vehicle combination having the features specified in patent claim 9.

[0009] Features, advantages, and advantageous embodiments of the method according to the invention are to be regarded as features, advantages, and advantageous embodiments of the assistance system according to the invention, the trailer vehicle according to the invention, and the vehicle combination according to the invention, and vice versa. Features, advantages, and advantageous embodiments of the safety system according to the invention are to be regarded as features, advantages, and advantageous embodiments of the trailer vehicle according to the invention and the vehicle combination according to the invention, and vice versa. Features, advantages, and advantageous embodiments of the trailer vehicle according to the invention are to be regarded as features, advantages, and advantageous embodiments of the vehicle combination according to the invention, and vice versa.

[0010] A first aspect of the invention relates to a method for operating a safety system for a vehicle combination comprising a towing vehicle and a trailer vehicle that are coupled to one another. This means that the vehicle combination has a coupling device formed by a towing vehicle-side coupling element and a trailer-side coupling element, wherein the coupling elements correspond to one another. When the coupling device is closed, i.e., the two coupling elements are engaged with one another, the towing vehicle and the trailer vehicle are coupled to one another, thereby forming the vehicle combination.

[0011] The towing vehicle is, in particular, a motor vehicle, especially a passenger car and / or a truck. Furthermore, if considered a solo vehicle, the towing vehicle can be a self-propelled work machine, such as a tractor unit.

[0012] The trailer vehicle has a trailer-side drive unit by means of which a drive torque can be provided that is independent of the towing vehicle. This means that in the method, the drive torque is provided by means of the trailer-side drive unit, which is independent of the towing vehicle. The trailer-side drive unit is preferably an electric drive unit, so that the trailer vehicle and / or the towing vehicle can be driven or moved at least partially electrically by means of the drive unit. For example, it can be provided that the trailer vehicle is specifically accelerated by means of the trailer-side drive unit, so that the vehicle combination can then be operated in a particularly fuel- and / or energy-efficient manner or with low emissions.

[0013] The trailer-side drive unit is arranged in / on the trailer vehicle and acts directly or indirectly on the wheels of the trailer vehicle for speed-reducing acceleration (“braking”), for speed-increasing acceleration (“acceleration”) and / or for steering the trailer vehicle. In particular, the drive unit acts on the wheels of the trailer vehicle individually. Furthermore, the trailer-side electric drive unit has at least one electric machine, preferably at least two electric machines, which can be, for example, a respective wheel hub motor, for example a respective traction motor close to a wheel. Accordingly, the trailer-side drive unit has at least one electrical energy store, for example an electrical traction accumulator, by means of which the electrical machine orElectrical drive energy can be or is provided to the electrical machines. In other words, the trailer-side drive unit is designed as an electric drive unit, so that the trailer vehicle can be driven or propelled at least partially electrically by means of the electric drive unit.

[0014] In the method for operating the safety system for the vehicle combination, an articulation angle of the vehicle combination between the towing vehicle and the trailer vehicle is further detected by means of an angle detection unit - which can have an angle sensor, for example - and provided to the trailer-side drive unit. For this purpose, the trailer-side drive unit can have a control unit, for example, to which the articulation angle is provided in digital form, for example as a data set, by means of the angle detection unit. Based on the articulation angle of the vehicle combination, in particular based on a current articulation angle of the vehicle combination, the method then provides that the trailer-side drive unit controls the trailer vehicle based on the articulation angle, i.e., for example, brakes and / or drives it.

[0015] In order to further increase road safety in a particularly advantageous and efficient manner, the invention provides that, based on the articulation angle, the trailer-side drive unit applies an additional braking torque to the inside wheel of the trailer vehicle, while simultaneously applying an additional driving torque to the outside wheel of the trailer vehicle. The inside wheel and the outside wheel are arranged at opposite ends of a trailer vehicle axle, with this trailer vehicle axle running parallel to a transverse axle of the trailer vehicle.

[0016] This increases the driving stability of the vehicle combination in a particularly efficient manner, since the additional torque of the trailer vehicle on the coupling device generates a force component acting in the transverse direction of the vehicle, which counteracts any buckling or collapsing of the vehicle combination. It is particularly preferred if the additional braking torque on the inside wheel of the trailer vehicle and the driving torque on the outside wheel of the trailer vehicle are each selected such that any buckling or collapsing of the vehicle combination is counteracted depending on the articulation angle. Accordingly, the additional torques generate a yaw moment about a vertical axis of the trailer vehicle, the direction of rotation of which yaw moment is arranged such that a trailer-side coupling element of a coupling device, via which the towing vehicle and the trailer vehicle are coupled to one another, tends to move towards the inside of the curve.This effectively prevents the towing vehicle from swerving to the outside of the curve and, as a result, the vehicle combination from buckling or collapsing.

[0017] In a further embodiment of the method, the additional braking torque on the inside wheel of the trailer vehicle and the additional driving torque on the outside wheel of the trailer vehicle are equal in magnitude. This means that the same torque amount is used for both the additional braking torque and the additional driving torque, with the additional braking torque having a negative sign and the additional driving torque having a positive sign.

[0018] By applying the additional braking torque to the inside wheel of the curve and applying the additional driving torque of the same magnitude to the outside wheel of the curve, the force directed towards the inside of the curve is generated at the coupling device, whereby a resulting coupling force acts on the coupling device in the direction of the towing vehicle, whereby in the ideal case a longitudinal axis of the towing vehicle and the force vector of that coupling force coincide.

[0019] This enables a particularly stable driving condition of the towing vehicle and consequently of the vehicle combination.

[0020] According to the invention, the articulation angle can be determined by determining the curvature of the towing vehicle and the curvature of the trailer. The curvature of the towing vehicle is the quotient of the yaw rate and the driving speed of the towing vehicle, and the curvature of the trailer vehicle is the quotient of the yaw rate and the driving speed of the trailer vehicle. A yaw rate or yaw rate is the rotational speed or angular speed of the corresponding vehicle about a vertical axis of that vehicle. In addition, the articulation angle can be detected using the angle sensor system.

[0021] In general, the curvature of a curve is the mathematical inverse of the radius of that curve. This means that the curve curvature of the towing vehicle or trailer vehicle is the mathematical inverse of the curve that the towing vehicle or trailer vehicle is driving through or on. The respective curve curvature is determined from a respective yaw rate, which can also be referred to as yaw velocity. The yaw rate of the towing vehicle is the rotational speed of the towing vehicle about its vertical axis, or Z-axis. Accordingly, the yaw rate of the trailer vehicle is the rotational speed of the trailer vehicle about its vertical axis, i.e., about the W-axis. The respective yaw rate can be determined or detected using the respective yaw rate sensors.Alternatively or additionally, the respective yaw rate can be determined by dividing the difference between the rolling speeds of the inside wheel and the outside wheel by the track width of the corresponding vehicle.

[0022] To determine the articulation angle, a first partial angle is determined relative to a curve center assigned to the trailer vehicle between an instantaneous center of the trailer vehicle axle and the coupling device. A second partial angle of the articulation angle is determined relative to a curve center assigned to the towing vehicle between the coupling device and an instantaneous center of a rear axle of the towing vehicle. The total articulation angle of the vehicle combination is then calculated by summing the two partial angles.

[0023] For this purpose, the angle detection unit comprises, for example, a yaw rate sensor to detect the corresponding yaw rates of the respective vehicles, so that the articulation angle of the vehicle combination can then be determined during the process, for example, by the control unit. If the angle detection unit comprises both the angle sensor (for directly detecting the articulation angle of the vehicle combination) and the yaw rate sensor (for indirectly detecting the articulation angle of the vehicle combination via the wheel speed difference), the detection of the articulation angle is particularly precise and reliable, since, for example, a plausibility check of a sensor result from the angle sensor and / or a sensor result from the yaw rate sensor can be performed.

[0024] If, as already mentioned, the yaw rate of the respective vehicle is determined based on the difference in the rolling speeds of the outside wheel and the inside wheel, mathematical integration of the yaw rate sensor readings is advantageously eliminated. This is because there is a possibility that an error value, such as an offset between two sensor signals, is integrated during the mathematical integration operation. Thus, if mathematical integration (i.e., an integral calculation) is omitted when determining the articulation angle, it is particularly reliable and error-free, and can be determined particularly over long periods of time.

[0025] In a second aspect, the invention relates to a safety system for a vehicle combination configured to carry out a method according to the above description. This means that the safety system has means for carrying out method steps of the method. The safety system can be arranged, in particular, at least partially on / in the towing vehicle of the vehicle combination. Alternatively or additionally, the safety system can be arranged, at least partially, on / in the trailer vehicle.

[0026] The second aspect of the invention also encompasses further developments of the security system according to the invention that have features already described in connection with the further developments of the method according to the invention. Therefore, the corresponding further developments of the security system according to the invention are not described again here.

[0027] The invention comprises a third aspect, according to which a trailer vehicle is proposed which can be coupled to a towing vehicle and which has, at least in part, a safety system according to the above description.

[0028] If this safety system is used in / on a vehicle combination, i.e. in / on the towing vehicle and / or in / on the trailer vehicle, road safety is increased in a particularly efficient manner.

[0029] In a further advantageous embodiment of the trailer vehicle, it is provided that it has a trailer-side drive unit by means of which a drive torque can be provided that is independent of the towing vehicle. For example, it is provided that the trailer-side drive unit is designed to support the driving operation of the vehicle combination. This is because today in vehicle construction, particularly series vehicle construction, there is a need to develop vehicles with electric drive systems that can achieve particularly long ranges between two necessary electrical charging processes. However, towing a (non-powered) trailer conflicts with this goal. This is where the trailer-side drive unit comes into play, at least reducing the range disadvantage due to towing the trailer.

[0030] A further advantageous embodiment of the trailer vehicle provides that it has a trailer axle, which has a respective wheel of the trailer vehicle at its lateral ends, wherein the wheels can be driven independently of one another, i.e., individually, by means of the trailer-side drive unit. As a result, yaw moments can be generated by the electric drive unit—alternatively or in addition to pure braking and / or acceleration along the longitudinal axis of the trailer vehicle—by driving a right wheel of the trailer vehicle axle and a left wheel of the trailer vehicle axle individually, for example, by means of two independently operable electric motors.

[0031] Such an appropriately designed trailer vehicle provides a so-called mover function, which enables maneuvering at particularly low speeds, for example at a campsite, particularly effectively, even independently of a towing vehicle.

[0032] Particularly in connection with the safety system, the ability to control the wheels of the trailer vehicle individually makes it possible to generate a yaw moment while the trailer vehicle is driving, and in particular while the vehicle combination is driving, in order to influence the current driving state of the trailer vehicle - and consequently the driving state of the vehicle combination. Furthermore, this yaw moment, which is generated in / on the trailer vehicle, can be used via the trailer-side coupling element and the towing vehicle-side coupling element to influence the current driving state of the towing vehicle - and consequently the driving state of the vehicle combination. For example, if the safety system detects when the method is being carried out that a jackknifing orIf the vehicle combination threatens to collapse, this can be counteracted efficiently by controlling the wheels of the trailer vehicle individually.

[0033] The third aspect of the invention, i.e., the trailer vehicle according to the invention, also includes further developments of the trailer vehicle according to the invention that have features already described in connection with the further developments of the method according to the invention and / or the safety system according to the invention. For this reason, the corresponding further developments of the trailer vehicle according to the invention are not described again here.

[0034] Finally, in a fourth aspect, the invention relates to a vehicle combination comprising a towing vehicle and a trailer vehicle. The towing vehicle and the trailer vehicle are designed in particular according to the above description.

[0035] The vehicle combination according to the invention contributes to particularly high or increased road safety by having the safety system at least partially integrated in / on the towing vehicle. This means that the vehicle combination has the safety system. The safety system can be integrated at least partially on / in the towing vehicle and / or on / in the trailer vehicle.

[0036] The vehicle combination, i.e., the fourth aspect of the invention, also includes further developments of the vehicle combination that have features already described in connection with the further developments of the method according to the invention, the safety system according to the invention, and / or the trailer vehicle according to the invention. Therefore, the corresponding further developments of the vehicle combination according to the invention are not described again here.

[0037] The invention also includes combinations of the features of the described embodiments.

[0038] An exemplary embodiment of the invention is described below. The single figure shows a schematic representation of a vehicle combination consisting of a towing vehicle and a trailer vehicle coupled to it, with the towing vehicle and the trailer vehicle shown cut away from each other.

[0039] The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

[0040] In the single figure, functionally identical elements are provided with the same reference numerals.

[0041] The following describes a vehicle combination 1 comprising a towing vehicle 2 and a trailer 3, a method for operating a safety system 4 for the vehicle combination 1, the safety system 4, and the trailer 3 together. The single figure shows a schematic representation of the vehicle combination 1 with the towing vehicle 2 and the trailer 3 coupled to it, with the towing vehicle 2 and the trailer 3 shown cut away from each other.

[0042] For the sake of simplicity of description, the figure shows a coordinate system (x, y, z) assigned to the towing vehicle 2 and a coordinate system (u, v, w) assigned to the trailer vehicle 3. Starting from a ground plane (not shown), on which the towing vehicle 2 is positioned as intended, the X-direction points parallel to the ground plane in a forward direction of travel of the towing vehicle 2, such that the X-axis runs parallel, in particular collinear, to a longitudinal axis 5 of the towing vehicle 2. In other words, the X-axis represents the longitudinal axis 5 of the towing vehicle 2. The X-axis therefore points forward with respect to the towing vehicle 2.

[0043] The Y-direction points parallel to the ground plane and perpendicular to the X-axis in a transverse direction of the towing vehicle 2, so that the Y-axis runs parallel, in particular collinear, to a transverse axis 6 of the towing vehicle 2. In other words, the Y-axis represents the transverse axis 6 of the towing vehicle 2. The Y-axis therefore points to the left with respect to the towing vehicle 2 or with respect to its forward direction of travel (X-direction).

[0044] The Z-axis points vertically to the X-axis and vertically to the Y-axis relative to the ground plane, i.e., upwards. Thus, the Z-axis is parallel, in particular collinear, to a vertical axis 7 of the towing vehicle 2. In other words, the Z-axis represents the vertical axis 7 of the towing vehicle 2.

[0045] Analogously, the U-axis of the coordinate system (u, v, w) assigned to the trailer vehicle 3 represents a longitudinal axis 8 of the trailer vehicle 3, the V-axis represents a transverse axis 9 of the trailer vehicle 3 and the W-axis represents a vertical axis 10 of the trailer vehicle 3.

[0046] The towing vehicle 2 has a first axle 11, in this example the front axle, on which - relative to the vehicle's longitudinal axis 5 - a wheel 12, for example designed as a tire-rim combination, is mounted on the right and left sides. The front, i.e. first, axle 11 is steerable, so that the towing vehicle 2 and consequently the vehicle combination 1 can corner. Along the vehicle's longitudinal axis 5, opposite the forward direction of travel or X-direction, the towing vehicle 2 has a second axle 13, in this example the rear axle, on which a wheel 12 is also mounted on the right and left sides of the vehicle's longitudinal axis 5.

[0047] The trailer vehicle 3 is designed to be towed by the towing vehicle 2 or by means of the towing vehicle 2. For this purpose, the vehicle combination 1 has a coupling device 14 formed by a towing-vehicle-side coupling element 15 and a trailer-side coupling element 16 corresponding to the towing-vehicle-side coupling element 15. When the coupling device 14 is closed, i.e., when the two coupling elements 15, 16 are engaged with one another, the towing vehicle 2 and the trailer vehicle 3 are coupled to one another, thereby forming the vehicle combination 1.

[0048] The trailer-side coupling element 16 is spaced a distance 17 from an axle 18 of the trailer vehicle 3 along the vehicle's longitudinal axis 8 and in the forward direction of travel of the trailer vehicle 3, i.e., in the U-direction. Thus, if the vehicle combination 1 is formed by the two coupling elements 15, 16 engaging with one another, the coupling device 14 is spaced a distance 17 from the axle 18 of the trailer vehicle 3. The trailer vehicle 3 has a wheel 19 on the left side of the axle 18 and another wheel 20 on the right side (relative to the vehicle's longitudinal axis 8 of the trailer vehicle 3).

[0049] The vehicle combination 1 formed in the present example by the towing vehicle 2 and the trailer vehicle 3 is merely exemplary. It goes without saying that the towing vehicle 2 can have more axles than axles 11, 13. The same applies to the trailer vehicle 3, which can have more axles than axle 18. Furthermore, it can be provided, in particular, that instead of the respective wheel 12, 19, 20 on the corresponding axle 11, 13 and / or 18, a wheel group can be used. This is particularly the case with rear axles designed as so-called tandem axles, on which a wheel group, for example a twin wheel, can be formed.

[0050] The vehicle combination 1 comprises the safety system 4. This means that the safety system 4 can be arranged entirely in the trailer vehicle 3 or entirely in the towing vehicle 2. Alternatively, the safety system 4 can be arranged partially in the trailer vehicle 3 and partially in the towing vehicle 2. Then, at least one component 21 of the safety system 4 arranged in the trailer vehicle 3 and one component 22 of the safety system 4 arranged in the towing vehicle 2 could together form the safety system 4.

[0051] In the present example, the trailer-side component 21 of the security system 4 is an electronic computing device 23, for example a computer unit.

[0052] The trailer vehicle 3 provides a drive torque 24 that is independent of the towing vehicle 2 and is generated or provided, for example, by means of a trailer-side drive unit 25. In other words, the trailer vehicle 3 has the trailer-side drive unit 25. This is designed separately from the towing vehicle 2. It can further be provided that the trailer-side drive unit 25 can be operated independently of the towing vehicle 2. For example, the trailer vehicle 3 can then be maneuvered or otherwise manoeuvred particularly easily and with little effort on its own, i.e. when it is uncoupled from the towing vehicle 2, since the required drive torque 24 is provided independently of the towing vehicle 2 by means of the trailer-side drive unit 25.In this context, it is particularly advantageous if the trailer-side drive unit 25 has wheel hub motors 26, by means of which the left-hand wheel 19 and the right-hand wheel 20 of the trailer vehicle 3 can be driven separately from one another.

[0053] The vehicle combination 1, i.e. the towing vehicle 2 and / or the trailer vehicle 3, in the present example the trailer vehicle 3, has an angle detection unit 27, by means of which a bend angle κ of the vehicle combination 1 is detected. When the vehicle combination 1 is cornering - i.e. when the vehicle combination 1 is not stretched - the bend angle κ occurs as an angle different from 0 degrees between the longitudinal axis 5 of the towing vehicle 2 and the longitudinal axis 8 of the trailer vehicle 3. This means that the bend angle κ is 0 degrees when the vehicle combination 1 is stretched, i.e. when the vehicle combination 1 is traveling straight ahead.

[0054] The angle detection unit 27 can, for example, have an angle sensor system. Alternatively or additionally, the angle detection unit 27 can have a wheel speed sensor system to determine the articulation angle κ between the towing vehicle 2 and the trailer vehicle 3 based on wheel speed differences of the wheels 12 and / or the wheels 19, 20. The wheel speed sensor system can be part of a slip control system, for example an ABS (anti-lock braking system or ABV: automatic anti-lock system) or an ESP (electronic stability program). In any case, the angle detection unit 27 is designed to provide the trailer-side drive unit 25 with the articulation angle κ existing between the towing vehicle 2 and the trailer vehicle 3. For example, the articulation angle κ is provided to the trailer-side drive unit 25 in data form or in digital form, for example as a data set characterizing the current articulation angle κ.For this purpose, the angle detection unit 27 is coupled or can be coupled to the trailer-side drive unit 25.

[0055] In particular, the angle detection unit 27 and the trailer-side drive unit 25 can be coupled to one another via the safety system 4, in this case coupled to one another. This means that the trailer-side drive unit 25 and the angle detection unit 27 can be coupled, in this case coupled, to the safety system 4, in particular to its electronic computing device 23. In this case, it can be provided, for example, that the computing device 23 receives an angle signal characterizing the articulation angle κ or the angle data set characterizing the articulation angle κ from the angle detection unit 27 and, based thereon, controls the trailer-side drive unit 25 accordingly. This means that in the method, the trailer-side drive unit 25 controls the trailer vehicle 3 based on the articulation angle κ or as a function of the articulation angle κ. If, for example, there is a risk that the articulation angle κ becomes uncontrolled orincreases uncontrollably quickly, it is provided - in order to (re-)establish and / or maintain a stable driving condition of the vehicle combination 1 - that the drive torque 24 is reduced accordingly in order to prevent or stop the uncontrolled or uncontrollable increase in the articulation angle κ. In such a driving condition of the vehicle combination 1, in which the excessively rapid increase in the articulation angle κ is imminent or is currently occurring, the coupling device 14 urges the coupling elements 15, 16 towards the outside of the curve and a trailer-side yaw moment 28 and a towing vehicle-side yaw moment 29 occur, wherein a direction of rotation of the trailer-side yaw moment 28 and a direction of rotation of the towing vehicle-side yaw moment 29 are opposite to one another.

[0056] In order to influence these two yaw moments 28, 29 such that a resulting coupling force vector 31 and the towing vehicle-side vehicle longitudinal axis 5 coincide, the trailer-side drive unit 25 applies an additional braking torque 32 based on the articulation angle κ to the inside wheel 19 of the trailer vehicle 3, and simultaneously applies an additional driving torque 33 to the outside wheel 20 of the trailer vehicle 3. The additional torques 32, 33 are equal in magnitude. As a result, the driving stability of the vehicle combination 1 is increased and / or restored, since the additional moments 32, 33 result in a correction force vector 34 which, so to speak, rotates a coupling force vector 30 on the coupling device 14 in such a way that this runs as the resulting coupling force vector 31 along the towing vehicle-side vehicle longitudinal axis 5.

[0057] The respective additional moment 32, 33 is calculated using the formula DM=rTire⋅lvS⋅|Fx|⋅sin(κ) with DM additional moment 32, 39 r Reifen Radius of the corresponding wheel 19, 20 l v Distance 17 S gauge 35 F x Clutch force according to clutch force vector 30

[0058] This results in a drive torque of 37 for the inside wheel 19 Mkurveninnen=rTire⋅(Fx2−lvs⋅|Fx|⋅sin(κ)) and for a drive torque of 38 of the outer wheel 20 Mcurveouter=rTire⋅(Fx2−lvs⋅|Fx|⋅sin(κ)) where for F x or the coupling force vector 30 applies: Fx=FDrive−i⋅FBrake with F Antrieb Driving force i Reinforcement F Brems Braking force.

[0059] The gain i is a quotient of a sum of the wheel braking forces (F Brems) and the coupling force developed according to the coupling force vector 30. In this case, the gain i is usually in a range from i = 4 to i = 8. At i = 4, 4 / 5, i.e. 80%, of the trailer braking is applied by trailer vehicle 3 and 1 / 5, i.e. 20%, by towing vehicle 2. At i = 8, 8 / 9, i.e. 89%, of the trailer braking is applied by trailer vehicle 3 and 1 / 9, i.e. 11%, by towing vehicle 2. In this case, the gain i is set by a manufacturer of trailer vehicle 3 when trailer vehicle 3 is manufactured in accordance with legal regulations - for Europe in accordance with ECE-R13. ECE-R13 specifies a value of i ≥ 4 for trailer vehicles 3 of class O2.

[0060] The different drive torques 37, 38 applied to the wheels 19, 20 of the trailer vehicle 3 generate a yaw moment 39 turning into the curve. Accordingly, the yaw moment 39 drives the trailer-side coupling element 16 in the direction of a curve center point of the curve traversed by the vehicle combination 1. As a result, the correction force vector 34 is generated, which is a force component of the resulting coupling force vector 31 acting in the transverse direction v of the trailer vehicle 3. Corresponding force sums of the vehicle combination 1 remain unchanged by this measure, i.e. the vehicle combination 1 accelerates or decelerates in the same way as without these measures described herein. However, it is advantageous that the driving stability of the vehicle combination has been significantly increased by these measures described herein. List of reference symbols 1 vehicle combination 2 towing vehicle 3 trailer vehicle 4 Security system 5 Vehicle longitudinal axis 6 Vehicle transverse axle 7 Vehicle vertical axis 8 Vehicle longitudinal axis 9 Vehicle transverse axle 10 Vehicle vertical axis 11 Axis 12 wheels 13 Axis 14 Coupling device 15 Coupling element 16 Coupling element 17 Distance 18 Axis 19 wheels 20 wheels 21 Component 22 Component 23 Computing device 24 drive torque 25 drive unit 26 wheel hub motors 27 Angle detection unit 28 Yaw moment 29 Yaw moment 30 Clutch force vector 31 resulting coupling force vector 32 additional braking torque 33 additional driving torque 34 Correction force vector 35 Track width of the trailer vehicle 36 Track width of the towing vehicle 37 Drive torque of the inside wheel 38 Drive torque of the outside wheel 39 Yaw moment κ bending angle

Claims

[1] Method for operating a safety system (4) for a vehicle combination (1) comprising a towing vehicle (2) and a trailer vehicle (3) which are coupled to one another, and a trailer-side drive unit (25) provides a drive torque (24, 37, 38) independent of the towing vehicle (2), wherein an articulation angle (ĸ) of the vehicle combination (1) between the towing vehicle (2) and the trailer vehicle (3) is detected by means of an angle detection unit (27) and provided to the trailer-side drive unit (25), which controls the trailer vehicle (3) based on the articulation angle (ĸ), wherein, by means of the trailer-side drive unit (25), based on the articulation angle (ĸ), an inside wheel (19) of the trailer vehicle (3) is subjected to an additional braking torque (32) and, at the same time, an outside wheel (20) of the trailer vehicle (3) is subjected to a driving Additional moment (33) is applied characterized byin that, in order to detect the articulation angle (ĸ) of the vehicle combination (1), a curve curvature of the towing vehicle (2) is determined, which is a quotient of a yaw rate and a driving speed of the towing vehicle (2), and a curve curvature of the trailer vehicle (3) is determined, which is a quotient of a yaw rate and a driving speed of the trailer vehicle (3). [2] Method according to claim 1, characterized by that an amount of the additional braking torque (32) and an amount of the additional driving torque (33) are equal. [3] Method according to one of the preceding claims, characterized by that the yaw rate of the respective vehicle (2, 3) is a quotient of a speed difference between a rolling speed of an outside wheel (19) and a rolling speed of an inside wheel (20) of the corresponding vehicle and a track width measurement (35, 36) of the corresponding vehicle. [4] Safety system (4) for a vehicle combination (1) which is configured to carry out a method according to one of claims 1 to 3. [5] Trailer vehicle (3) which can be coupled to a towing vehicle (2), characterized by a security system (4) designed according to claim 4. [6] Trailer vehicle (3) according to claim 5, characterized by a trailer-side drive unit (25), by means of which a drive torque (24, 37, 38) independent of the towing vehicle (2) can be provided, wherein the trailer-side drive unit (25) is formed in particular from wheel hub motors or motors close to respective wheels of the trailer vehicle (3). [7] Trailer vehicle (3) according to claim 6, characterized by a trailer axle (18) having a respective wheel (19, 20) of the trailer (3) at its lateral ends, wherein the wheels (19, 20) can be driven independently of one another by means of the trailer-side drive unit (25). [8] Trailer vehicle (3) according to one of claims 5 to 7, characterized by that an additional braking torque (32) can be generated by means of a service brake assigned to the respective wheel of the trailer vehicle (3). [9] Vehicle combination (1) with a towing vehicle (2) and a trailer vehicle (3) designed according to one of claims 5 to 8, characterized by that the safety system (4) is at least partially formed in / on the towing vehicle (2).

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