Method for operating drive of trailer and trailer for vehicle combination

Abstract

The invention relates to a method for operating a drive of a trailer, in which a drive unit (8) of the trailer (3) is actuated by a drive signal, the drive signal being used to set a drive torque (M) of the drive unit (8) in order to avoid instability of a vehicle combination (1) containing the trailer (3), and the drive torque (M) being set as a function of a speed (v) of the trailer (3) or of the vehicle combination (1).

Description

Technical Field

[0001] The present invention relates to a method for operating a drive of a trailer and a trailer for a vehicle combination, in which a drive unit of the trailer is controlled by a drive signal, wherein the drive signal is used to set a drive torque of the drive unit in order to stabilize the vehicle combination including the trailer. The vehicle combination is preferably a wheeled vehicle combination and includes a passenger car or a truck as a towing vehicle. Background Art

[0002] Known trailers equipped with a drive unit used in vehicle combinations with a towing vehicle have an electric motor as the drive unit. To ensure the safe operation of electrically driven trailers in public road traffic, it is necessary to ensure that the drive system does not cause an unstable driving state for the entire vehicle combination. Driving situations involving large bending angles between the towing vehicle and trailer are particularly critical. In these situations, the towing vehicle could be unintentionally moved forward by the trailer, or the vehicle combination could fold, potentially destabilizing the entire vehicle combination. This folding, similar to a pocket knife, is known as the "jackknife phenomenon."

[0003] EP 3 845 441 A1 discloses a method for operating a trailer drive, in which a drive signal is adjusted according to the curvature of a curve. The torque applied to the trailer is regulated according to the current curve radius. The curve radius is determined by the wheel speeds of the trailer's individual wheels and determines the maximum available torque. Summary of the Invention

[0004] The object of the present invention is to overcome the disadvantages of the prior art and to specify a method which allows a vehicle combination to be driven safely in many traffic situations.

[0005] This object is achieved by a method according to claim 1. A method for operating a drive of a trailer is described, in which a drive unit of the trailer is controlled by a drive signal, wherein the drive signal is used to set a drive torque of the drive unit in order to stabilize a vehicle combination including the trailer, wherein the drive torque is set as a function of the speed of the trailer or the vehicle combination.

[0006] The object is also achieved by a trailer for a vehicle combination, comprising a drive unit and a control unit for controlling the drive unit, in which trailer the control unit is designed to carry out the method according to at least one of the features described in the present patent application.

[0007] In the proposed method, the speed information preferably derived from the independently driven trailer is the dominant influencing variable for determining the drive torque of the trailer drive. This is based on the recognition that narrow bends can only be driven at very low speeds, preferably at walking speed.

[0008] Smaller bend radii (those resulting in a larger bending angle between the towing vehicle and the trailer) are driven more slowly, whereas larger bend radii can be driven at higher speeds, since only smaller bending angles are expected, with the vehicle combination becoming increasingly stretched as the speed increases.

[0009] The kink angle is intended to refer to the deviation of the trailer from the longitudinal direction predetermined by the towing vehicle. Large kink angles between the towing vehicle and the trailer occur, for example, in bends on locations with turning conditions, roundabouts, or winding roads.

[0010] The method has the advantage of high system reliability. It eliminates the need for separate sensors to determine the kink angle between the towing vehicle and trailer, which reduces costs, maintenance, and upkeep. The method can be used regardless of trailer type, such as a central axle trailer or a saddle trailer.

[0011] In one embodiment, the permissible value of the drive torque of the drive unit is reduced when the speed of the trailer vehicle or vehicle combination falls below a speed threshold. The speed threshold allows for a simple distinction between driving situations that are hazardous and those that are not. A decision is made as to whether the trailer vehicle should be driven. The speed threshold is set such that, above the speed threshold, it is unlikely, within the framework of driving physics, to negotiate a narrow curve with a large bend angle between the towing vehicle and the trailer.

[0012] In another embodiment, the torque of the electric motor serving as the drive unit is set as the driving torque of the electrically driven trailer, depending on the speed of the trailer or vehicle combination. The torque describes the force applied to the drive shaft of the electric motor. Below a speed threshold, the torque of the electric motor is limited to 0 Nm, meaning the trailer is no longer driven. This method also enables the operation of electrified trailers without a saddle coupling or kingpin between the towing vehicle and trailer, particularly central-axle trailers.

[0013] In another embodiment, the permissible torque is increased as a function of the speed of the trailer vehicle or vehicle combination when a speed threshold is exceeded. This assumes that at higher speeds, the vehicle combination has only a small bending angle. The greater the speed, the more the vehicle combination may extend, as it is assumed that the vehicle combination tends to go straight.

[0014] In another embodiment, the speed of the trailer or vehicle combination is derived from redundant speed signals of the towing vehicle and / or additional speed information of the trailer. The redundancy resulting from both signals ensures that torque-based speed control is particularly safe and reliable. The redundant speed signal can be derived, in particular, from one or more wheel speeds and the engine speed of the trailer. By increasing the accuracy of the speed determination, the torque control of the trailer's electric motor is refined, and traffic safety of the vehicle combination is improved.

[0015] The aspects described herein with reference to the method also apply to the disclosed trailer, which has a controller for implementing the method. This can be accomplished by providing appropriate read and write access to a memory associated with the trailer. The method is implemented in the trailer, in particular, using hardware or software, or a combination of hardware and software. The controller hardware includes, in particular, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array, and other suitable switches and computing components. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Further features, advantages and properties of the present invention are explained with reference to the description of preferred embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A schematic diagram of a vehicle combination with a trailer according to the invention is shown;

[0018] Figure 2 A diagram showing a kink angle for defining a vehicle combination;

[0019] Figure 3 An exemplary embodiment of the inventive dependence of the speed of a trailer vehicle on the torque for driving the trailer vehicle is shown. DETAILED DESCRIPTION

[0020] exist Figure 1 1 shows a schematic diagram of a vehicle combination with a trailer according to the present invention. The vehicle combination 1 comprises a driven tractor vehicle 2 and an electrically driven trailer 3. The separately driven trailer 3 is used to increase the range of the motor-driven vehicle combination 1.

[0021] For their respective electric drives, the tractor vehicle 2 includes a first drive system 4 comprising a motor 5 and a first controller 6. The trailer 3 also has a drive system 7 comprising an electric motor 8 and a second controller 9. The second controller 9 is connected to wheel speed sensors 10 and a motor speed sensor 11. The second controller 9 determines the speed of the trailer 3 from the signals of the wheel speed sensors 10. The redundant speed of the trailer 3 is determined from the signal of the motor speed sensor 11.

[0022] The second controller determines the value of the torque M of the electric motor 8 for driving the trailer 3 based on the speed of the trailer 3. In this case, the kink angle between the tractor 2 and the trailer 3 is inferred from the speed of the trailer 3. The kink angle β is Figure 2 is shown in more detail in . When the vehicle combination 1 is traveling straight, the towing vehicle 2 and the trailer 3 are oriented along a common longitudinal direction L. If the vehicle combination 1 negotiates a curve, the trailer 3 deviates from this longitudinal direction L by a bending angle β. The greater this bending angle β, the more likely a critical traffic situation will occur. To prevent such critical traffic situations, the second controller 9 regulates the torque M based on the speed of the trailer 3.

[0023] exist Figure 3 An example of a dependency of the torque M of the electric motor 8 driving the trailer 3 on the speed of the trailer can be seen in FIG. The torque is set by the second controller 9. Based on the speed of the trailer 3, it is decided whether the trailer 3 should be driven. For this purpose, a speed threshold v of, for example, 30 km / h is defined. S If the currently known speed v of the trailer 3 is compared with the speed threshold v S When compared, it is confirmed that the speed is lower than the threshold value v S , then the second controller 9 does not control the torque M of the electric motor 8. That is to say, the trailer 3 is not driven. When the current measured speed v of the trailer 3 exceeds the speed threshold v S , then the torque M is determined to increase with the speed v. This increase in the torque M can occur linearly, but also as a nonlinear function of the speed v.

[0024] Reference Signs List

[0025] 1 vehicle combination

[0026] 2 Towing vehicles

[0027] 3 trailers

[0028] 4. Drive system of traction vehicle

[0029] 5 motors

[0030] 6 controllers

[0031] 7Trailer drive system

[0032] 8 electric motors

[0033] 9 controllers

[0034] 10 wheel speed sensor

[0035] 11 Motor speed sensor

[0036] vSpeed ​​of the trailer

[0037] v S Speed ​​threshold

[0038] M torque

[0039] β bend angle

[0040] L longitudinal direction

Claims

1. A method for operating a drive of a trailer vehicle, wherein a drive unit (8) of the trailer vehicle (3) is driven by a drive signal, wherein: The control signal is used to set the drive torque (M) of the drive unit (8) in order to prevent the vehicle combination (1) including the trailer (3) from becoming unstable, characterized in that the drive torque (M) is set as a function of the speed (v) of the trailer (3) or of the vehicle combination (1).

2. The method according to claim 1, characterized in that When the speed (v) of the trailer (3) or the vehicle combination (1) falls below a speed threshold (v S ), the allowable value of the driving torque (M) of the driving unit (8) is reduced.

3. The method according to claim 2, characterized in that Below the speed threshold (v S ) does not control the driving torque (M) of the drive unit (8).

4. The method according to claim 1, 2 or 3, characterized in that The torque (M) of an electric motor (8) serving as a drive unit is set as a drive moment of the electrically driven trailer (3) as a function of the speed (v) of the trailer (3) or of the vehicle combination (1).

5. The method according to claim 4, characterized in that In the case of a speed threshold (v S ) or a certain speed threshold, the torque (M) of the electric motor (8) is limited to 0 Nm.

6. The method according to claim 4 or 5, characterized in that Above the speed threshold (v S ) or a certain speed threshold, the permissible value of the torque (M) or the permissible value is increased depending on the speed (v) of the trailer (3) or the vehicle combination (1).

7. The method according to any one of claims 4 to 6, characterized in that A maximum permissible torque (Mmax) of the electric motor (8) is determined as a function of the speed (v) of the trailer vehicle (3) or of the vehicle combination (1).

8. The method according to any one of claims 4 to 7, characterized in that The speed (v) of the trailer vehicle (3) or of the vehicle combination (1) is derived from the redundant speed signal of the trailer vehicle (3).

9. The method according to any one of claims 4 to 8, characterized in that The speed (v) of the trailer vehicle (3) or of the vehicle combination (1) is derived from redundant speed signals of the trailer vehicle (3) and / or of the towing vehicle (2).

10. A trailer for a vehicle combination, the trailer comprising a drive unit (8) and a controller (9) for controlling the drive unit (8), characterized in that: The controller (9) is designed to carry out the method according to any of the preceding claims.

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