DE102006049541B4 - Method and device for determining a trailer support load - Google Patents

Abstract

Method for determining a trailer support load (G) which is exerted on the vehicle by a trailer load attached to a vehicle (1), comprising the steps: - determining an unloaded vehicle position before the trailer load is coupled to the vehicle (1), - coupling the vehicle Towing load, which a trailer support load (G) on the vehicle (1) exerts on the vehicle (1), - Determining a loaded vehicle position after the trailer load to the vehicle (1) has been coupled, - Determining a vehicle attitude change from the unloaded vehicle position and loaded vehicle position, and- Determining the trailer load imposed by the trailer load on the vehicle (1) (G) from the vehicle attitude change.

Description

The present invention relates to methods and apparatus for determining trailer support load exerted on the vehicle by a trailer load attached to a vehicle.

A trailer support load exerted on the vehicle by attaching a trailer to a vehicle is a safety-relevant parameter and influences the driving behavior of the vehicle. The trailer support load, which is exerted for example on a ball head of a trailer hitch by an attached trailer, is limited by design and should therefore not be exceeded during operation. For a user of the vehicle, however, compliance with the permissible trailer support load is difficult to ensure. Depending on the distribution of the load under certain circumstances, the permissible trailer support load can be exceeded very quickly. Exceeding the permissible trailer support load, the driving behavior of the vehicle can be significantly adversely affected or there is even a risk that the suspension of the trailer hitch breaks.

Furthermore, the operation of electronic aids to improve the driving behavior of the vehicle, such as a brake assist or an electronic stability program, can be adversely affected in its operation by the additional trailer support load.

The DE 10 2004 058 829 A1 discloses a device for measuring support forces on trailers, towing vehicles or trailers. With this device, tensile forces, compressive forces, torsional forces or torques are measured at various points of the vehicle or the trailer and displayed. For example, forces or moments are measured on a support wheel or other support, on the coupling, on the drawbar, on the load-bearing of the towing vehicle or on the axles of the towing vehicle. When loading these forces and moments can thus be controlled and, where appropriate, the weight distribution when loading the trailer can be corrected by Lastumverteilung. The forces or moments are mechanically, electrically, electronically, pneumatically, hydraulically or visually or in any other way recorded in the appropriate places.

The DE 103 18 005 A1 discloses a method for determining a driving parameter for a vehicle. For this purpose, force sensors are arranged between the vehicle body and the struts. From the measured strut forces can then calculate various driving parameters, such as the body mass, the axle mass distribution, the wheel individual Ersatzaufbaumassen, the static spring stiffness, the body accelerations and the wheel contact forces.

The DE 199 18 679 A1 discloses a vehicle blade detection system for determining vehicle mass and its distribution.

The DE 103 37 212 A1 discloses a system for determining a load condition of a vehicle or a trailer. The system includes a sensor device which detects the levels of the vehicle relative to the individual wheels or axles and outputs corresponding measurement signals, and an evaluation device which determines from the measurement signals the total weight of the vehicle.

Therefore, it is an object of the present invention, a trailer support load, which is applied by a vehicle-mounted trailer load on the vehicle to determine this to a user of the vehicle and thus to avoid exceeding the permissible trailer support load, or, for example, the determined To supply trailer support load to a driver assistance system, such as a brake assist or an electronic stability program, for this assistance system to take into account the trailer support load in the operation of the system.

This object is achieved by a method according to claim 1 and claim 7, a device for determining a trailer support load according to claim 9 and a vehicle according to claim 13. The dependent claims define preferred and advantageous embodiments of the invention.

The present invention provides a method of determining a trailer support load imposed on the vehicle by a trailer load attached to a vehicle. In the method, an unloaded vehicle position is determined before the towing load is coupled to the vehicle. Thereafter, the trailer load, which exerts a trailer support load on the vehicle, coupled to the vehicle. Then a loaded vehicle situation is determined. From the unloaded vehicle position and the loaded vehicle position a vehicle position change is determined. Finally, from the vehicle attitude change, the trailer support load exerted on the vehicle by the trailer load is determined.

Determining the current trailer support load, which by a trailer load on the Vehicle is exercised, allows a user of the vehicle to ensure that a maximum trailer support load is not exceeded. Further, the particular trailer support load may be used in the operation of driver assistance systems to improve the operation of these systems with an attached trailer load. This improves the driving behavior of the vehicle and thus increases the driving safety of the vehicle.

According to a preferred embodiment, the unloaded vehicle position and the loaded vehicle position is determined by measuring at least one spring travel of an axle of the vehicle. Alternatively, the spring travel can be measured on the front axle of the vehicle and on the rear axle of the vehicle for determining the unloaded and loaded vehicle position, or the spring travel can be measured on each wheel of the vehicle for determining the unloaded and loaded vehicle position.

Measuring a spring travel provides a simple and inexpensive means of determining vehicle attitude. Furthermore, such means for measuring a spring travel may already be present in the vehicle as part of a headlight range adjustment for the vehicle. Thus, a cost-effective application of the method for determining a trailer support load in a vehicle is possible.

According to a further preferred embodiment, a pitch angle of a longitudinal inclination of the vehicle can be measured in order to determine the loaded vehicle position and the unloaded vehicle position. In turn, means for determining the pitch angle of the vehicle may already be installed in the vehicle within the scope of headlamp leveling or a driver assistance system, whereby the costs for implementing the method for determining a trailer support load may be kept low.

When using the spring travel or the pitch angle to determine the loaded and unloaded vehicle position calibrated support load characteristics of the spring travel or the pitch angle can be used to take into account a friction in the axles of the vehicle.

By using the calibrated characteristics, in determining the trailer support load, distorting influences caused by the friction in the axles of the vehicle can be eliminated and thus the accuracy of determining the trailer support load applied to the vehicle by the trailer load can be improved.

According to a preferred embodiment, the trailer support load exerted on the vehicle by the trailer load is displayed in a dashboard of the vehicle.

By the particular trailer support load is displayed in the instrument panel, the user of the vehicle is given the opportunity to detect exceeding the maximum permissible trailer support load and thus to avoid operation of the vehicle with exceeded maximum trailer support load and thus to ensure the safety of the vehicle.

The present invention further provides an apparatus for determining a trailer support load exerted on the vehicle by a trailer load attached to a vehicle, comprising at least one transducer and a computing unit. The at least one sensor is designed to determine a vehicle position of the vehicle. The arithmetic unit is connected to the at least one sensor and designed to carry out one of the previously explained methods.

The device may further include a user guide that guides the user to perform the methods described above.

By such a device, a correct implementation of the method described above is ensured and thus reliably determines the vehicle acting on the trailer trailer load.

The device may further be connected to a display unit of the vehicle to display both the user guidance and the determined trailer support load on the display unit.

The at least one transducer of the device may comprise a spring travel sensor or a pitch angle sensor.

This flexibility of the types of sensors used to determine the trailer support load is a cost-effective implementation of the method and apparatus in a vehicle possible by recourse to sensors, which may already be present, for example, for headlight range control or a driver assistance system.

The invention further provides a vehicle configured with an apparatus for determining trailer support load as previously described. Such a ausgestaltetes vehicle has a significantly improved traffic safety by unintentional exceeding of the permissible trailer support load can be avoided and driver assistance systems of the vehicle can adjust their operation, taking into account the specific trailer support load.

• 1 zeigt ein Fahrzeug, welches mit einer Vorrichtung zum Bestimmen einer Anhängerstützlast ausgestattet ist;
• 2 zeigt ein vereinfachtes Fahrzeugmodell ohne eine angehängte Anhängerstützlast;
• 3 zeigt ein vereinfachtes Fahrzeugmodell mit einer angehängten Anhängerstützlast;
• 4 zeigt ein vereinfachtes Fahrzeugnickmodell ohne angehängte Anhängerstützlast;
• 5 zeigt ein vereinfachtes Fahrzeugnickmodell mit einer angehängten Anhängerstützlast.

The present invention will be described below with reference to the accompanying drawings with reference to preferred embodiments.

• 1 shows a vehicle which is equipped with a device for determining a trailer support load;
• 2 shows a simplified vehicle model without an attached trailer support load;
• 3 shows a simplified vehicle model with an attached trailer support load;
• 4 shows a simplified vehicle nodding model without attached trailer support load;
• 5 shows a simplified vehicle nodding model with an attached trailer support load.

1 shows a vehicle 1 , which is equipped with a device for determining a trailer support load G _A , which by a trailer attached to a vehicle to the vehicle 1 is exercised. The device comprises four transducers 2 . 3 , each one wheel 4 . 5 are assigned to the vehicle. In 1 are just the two transducers 2 . 3 shown which the left front wheel 4 or the left rear wheel 5 of the vehicle 1 assigned. The two transducers, not shown, are accordingly assigned to the right front wheel or right rear wheel, not shown. The transducers 2 . 3 are with a computing unit 6 connected to the device for determining the trailer support load, as indicated by the dashed line in 1 shown. The arithmetic unit 6 is also with a display and control unit 7 in the dashboard of the vehicle 1 connected. To connect the vehicle 1 with a trailer load (not shown) is the vehicle 1 with a trailer hitch 8th fitted.

The determination of a trailer support load G _A is done as follows: In the state in which the trailer load of the vehicle 1 is decoupled, the user of the vehicle starts by operating an operating means of the display and control unit 7 the process for determining the trailer support load. The arithmetic unit then determines 6 the current measured values of the transducers 2 . 3 and stores these values in a memory of the arithmetic unit 6 , When the measurement is completed, the user of the vehicle 1 via the operating and display unit 7 from the arithmetic unit 6 prompted to couple the trailer load, which carries a trailer support load on the vehicle to the vehicle. After the user of the vehicle has coupled the towing load, he confirms this process by pressing another operating means of the control and display unit 7 , The arithmetic unit then determines 6 again the now valid measuring values of the transducers 2 . 3 and calculates from the difference between the previously measured and buffered measured values and the now current measured values that from the trailer load to the trailer hitch 8th applied trailer support load according to one of the methods described below. Finally, the particular trailer support load is displayed by the computing unit on the display and control unit.

2 shows a simplified vehicle model of the vehicle 1 , The vehicle 1 is equipped with such a spring system that the weight G _F of the vehicle via four springs 9 - 12 , which are each associated with a wheel of the vehicle, on the ground 13 on which the vehicle 1 stands, is transferred. Depending on the weight distribution within the vehicle 1 be over the feathers 9 - 12 different weights of the weight of the vehicle on the ground 13 transfer. To keep the vehicle in balance, set the springs 9 - 12 while supporting forces F _VL . F _VR . F _HL and F _HR at the left front wheel, the right front wheel, the left rear wheel and the right rear wheel, respectively. The equation applies to the stationary vehicle. $$F_{VL}+F_{VR}+F_{HL}+F_{HR}=G_F$$

Now by attaching a trailer load to the trailer hitch 8th a trailer support load G _A on the vehicle 1 exercised, so will next to the weight G _F now also the trailer support load G _A over the four springs 9 - 12 on the ground 13 transfer. As in 2 Accordingly, the springs change accordingly 9 - 12 applied supporting forces such that the supporting forces on the front axle F _VL and F _VR be reduced and the support forces on the rear axle F _HL and F _HR be enlarged. A change of support forces is in 3 denoted by ΔF _VL , ΔF _VR , ΔF _HL and ΔF _HR . For the stationary vehicle 1 then the equation applies: $$\mathrm{\Delta }{F}_{Hl}+\mathrm{\Delta }{F}_{HR}-\mathrm{\Delta }{F}_{VL}-\mathrm{\Delta }{F}_{VR}=G_A$$

$$\mathrm{\Delta }{F}_{VR}=C_{VR}\cdot \mathrm{\Delta }{W}_{VR}$$

$$\mathrm{\Delta }{F}_{HL}=C_{HL}\cdot \mathrm{\Delta }{W}_{HL}$$

$$\mathrm{\Delta }{F}_{HR}=C_{HR}\cdot \mathrm{\Delta }{W}_{HR}$$

The support force changes ΔF _VL , ΔF _VR , ΔF _HL and ΔF _HR can be changed by changing the spring travel of the springs 9 - 12 and the spring characteristics of the springs 9 - 12 be determined. The transducers 2 . 3 are for measuring the spring travel of the springs 9 - 12 designed and the arithmetic unit 6 determines the spring travel change of each spring which is generated by applying the trailer support load to the vehicle. Out the spring travel changes ΔW _VL , ΔW _VR , ΔW _HL and ΔW _{HR of} the four springs 9 - 12 determines the arithmetic unit 6 then either directly from the spring characteristics the corresponding support force changes .DELTA.F _VL , .DELTA.F _VR , .DELTA.F _HL or .DELTA.F _HR or calculates the support force changes of the springs 9 - 12 from the stiffnesses C _VL , C _VR , C _HL and C _{HR of} the individual springs and the spring travel changes according to the following equations: $$\mathrm{\Delta }{F}_{VL}=C_{VL}\cdot \mathrm{\Delta }{W}_{VL}$$

$$\mathrm{\Delta }{F}_{VR}=C_{VR}\cdot \mathrm{\Delta }{W}_{VR}$$

$$\mathrm{\Delta }{F}_{HL}=C_{HL}\cdot \mathrm{\Delta }{W}_{HL}$$

$$\mathrm{\Delta }{F}_{HR}=C_{HR}\cdot \mathrm{\Delta }{W}_{HR}$$

Thus, the arithmetic unit 6 on changes in spring travel of the springs 9 - 12 the trailer support load acting on the vehicle G _A determine.

$$F_H=\frac{l_V}{l}\cdot G_F$$

Alternatively, the trailer support load G _A also from a pitch angle of the structure of the vehicle 1 be determined. 4 shows a simplified vehicle nodding model of a vehicle 1 where S is the center of gravity of the structure. For simplicity, in this illustration, the springs of the front axle to a spring 14 summarized, which is a supporting force F _V applies, and the springs of the rear axle to a spring 15 summarized, which is a supporting force F _H on the construction of the vehicle 1 exercises. In the stationary state of the vehicle 1 can the weight of the vehicle 1 as a force G _F which are in focus F of the vehicle 1 attacks. The horizontal distance of the supporting force of the front springs F _V to the main focus S of the vehicle 1 is I _V and the horizontal distance of the support force F _H the springs of the rear axle to the center of gravity S of the vehicle 1 is I _H , The total horizontal distance between the point of application of the support force of the front springs F _V and the point of application of the supporting force of the rear springs F _H is I. Thus arise from the weight G _F the construction of the vehicle 1 and the arrangement of the springs of the front and rear axles following supporting force F _V and F _H : $$F_V=\frac{l_H}{l}\cdot G_F$$

$$F_H=\frac{l_V}{l}\cdot G_F$$

$$F_{HA}=F_H+\frac{l_{AV}}{l}\cdot G_A$$

By attaching a trailer load to the coupling 8th of the vehicle 1 and exerting a trailer support load G _A on the vehicle 1 the support forces of the springs on the front and rear axle change. The springs of the front axle are relieved and the springs of the rear axle are loaded. 5 shows a simplified vehicle nodding model with a trailer. From the moment equations around the front axle V and the rear axle H arise the supporting forces of the springs of the front axle F _VA and the springs of the rear axle F _HA taking into account the trailer support load exerted by the trailer G _A to: $$F_{VA}=F_V-\frac{l_{AH}}{l}\cdot G_A$$

$$F_{HA}=F_H+\frac{l_{AV}}{l}\cdot G_A$$

$$\mathrm{\Delta }{F}_H=\frac{l_{AV}}{l}\cdot G_A$$

This designates I _AH the distance of the trailer load applied by the trailer load G _A to the rear axle H and I _AV the distance of the trailer support load G _A to the front axle V , From the equations (8) and (10), the change of the supporting forces of the front springs ΔF _v and the rear springs ΔF _{H is determined} from the following equations: $$\mathrm{\Delta }{F}_V=\frac{l_{AH}}{l}\cdot G$$

$$\mathrm{\Delta }{F}_H=\frac{l_{AV}}{l}\cdot G_A$$

$$\mathrm{\Delta }{W}_H=\frac{l_{AV}}{l}\cdot \frac{G_A}{C_H}$$

Accordingly, a change of the spring travel at the front axle ΔW _V and at the rear axle ΔW _{H is} calculated using the stiffnesses of the front springs C _V and the rear springs C _H using the following equations: $$\mathrm{\Delta }{W}_V=\frac{l_{AH}}{l}\cdot \frac{G_A}{C_V}$$

$$\mathrm{\Delta }{W}_H=\frac{l_{AV}}{l}\cdot \frac{G_A}{C_H}$$

The one by the trailer support load G _A resulting pitch angle α thus results from the equation: $$\text{tan}\alpha =\frac{\mathrm{\Delta }{W}_H-\mathrm{\Delta }{W}_V}{l}$$

woraus die Anhängerstützlast G_A folgendermaßen berechnet werden kann: $$G_A=\frac{l^2{C}_V{C}_H}{\left(l_{AV}{C}_V-l_{AH}{C}_H\right)}\cdot \text{tan}\alpha$$

From the equations (13) - (15) it follows: $$\text{tan}\alpha =\frac{G_A}{l^2{C}_V{C}_H}\cdot \left(l_{AV}{C}_V-l_{AH}{C}_H\right).$$

from which the trailer support load G _A can be calculated as follows: $$G_A=\frac{l^2{C}_V{C}_H}{\left(l_{AV}{C}_V-l_{AH}{C}_H\right)}\cdot \text{tan}\alpha$$

Because at a small angle α tana in about α corresponds, is the trailer support load G _A for small angles linear to the pitch angle α according to the following equation: $$G_A=\frac{l^2{C}_V{C}_H}{\left(l_{AV}{C}_V-l_{AH}{C}_H\right)}\cdot \alpha$$

Thus, the arithmetic unit 6 in a simple way from the pitch angle a, the geometric dimensions of the vehicle and the spring stiffness of the vehicle, the trailer support load G _A to calculate.

$$G_A=\frac{l}{l_{AV}}\cdot \mathrm{\Delta }{W}_H\cdot C_H$$

Alternatively, if only one transducer 2 . 3 on either the front axle V or the rear axle H of the vehicle 1 is available, using the equations (13) or (14) the trailer support load G _A be determined if the transducer 2 . 3 is configured to measure a change in a spring travel of the front axle .DELTA.W _V or a change in the suspension travel of the rear axle .DELTA.W _H. Equations (19) and (20) then result from equations (13) and (14): $$G_A=\frac{l}{l_{AH}}\cdot \mathrm{\Delta }{W}_V\cdot C_V$$

$$G_A=\frac{l}{l_{AV}}\cdot \mathrm{\Delta }{W}_H\cdot C_H$$

$$\mathrm{\Delta }{F}_H=C_{HL}\cdot \mathrm{\Delta }{W}_{HL}+C_{HR}\cdot \mathrm{\Delta }{W}_{HR}$$

Alternatively, the changes of the individual spring travel of the right and left front wheel ΔW _R or ΔW _L or the individual spring travel of the right and left rear wheel ΔW _R or ΔW _H via the sensor 2 . 3 the arithmetic unit 6 are available, the equations (3) - (6) result in the equations: $$\mathrm{\Delta }{F}_V=C_{VL}\cdot \mathrm{\Delta }{W}_{VL}+C_{VR}\cdot \mathrm{\Delta }{W}_{VR}$$

$$\mathrm{\Delta }{F}_H=C_{HL}\cdot \mathrm{\Delta }{W}_{HL}+C_{HR}\cdot \mathrm{\Delta }{W}_{HR}$$

$$G_A=\frac{l}{l_{AV}}\cdot \left(C_{HL}\cdot \mathrm{\Delta }{W}_{HL}+C_{HR}\cdot \mathrm{\Delta }{W}_{HR}\right)$$

From these equations and equations (11) and (12), the trailer support load is obtained G _A thus: $$G_A=\frac{l}{l_{AH}}\cdot \left(C_{VL}\cdot \mathrm{\Delta }{W}_{VL}+C_{VR}\cdot \mathrm{\Delta }{W}_{VR}\right)$$

$$G_A=\frac{l}{l_{AV}}\cdot \left(C_{HL}\cdot \mathrm{\Delta }{W}_{HL}+C_{HR}\cdot \mathrm{\Delta }{W}_{HR}\right)$$

Thus, in this case as well, if alternatively only transducers are provided for determining a spring deflection on individual wheels of either the front axle or the rear axle, an easy way out of the measurements and the geometric dimensions of the vehicle and the stiffnesses of the springs of the vehicle, the trailer support load G _A to determine.

In addition, the arithmetic unit 6 in determining the trailer support load G _A the friction of the axles, which occurs at each of the wheels, while the vehicle is descending due to the attached towing load, take into account in order to further increase the accuracy of the determination of the trailer support load. In this case, the arithmetic unit 6 use calibrated characteristics that represent the trailer support load as a function of the measured spring travel changes or the trailer support load as a function of the measured pitch angle.

LIST OF REFERENCE NUMBERS

1

vehicle

2, 3

transducer

4, 5

wheel

6

computer unit

7

operating unit

8th

trailer hitch

9

Spring front left

10

Spring front right

11

Spring in the back left

12

Spring in the back right

13

ground

14

Suspension front

15

Rear suspension

F _VL , F _VR , F _HL , F _HR

Support force of the single spring

G _F

Weight of the vehicle

G _A

Trailer support load

S

main emphasis

V

Front

H

rear axle

I _V

Distance center of gravity front axle

I _H

Distance center of gravity rear axle

I

Distance front-rear axle

F _V , F _H

Support force of the springs front and rear without trailer

F _VA , F _HA

Support force of the springs front and rear with trailer

α

Nick angle of the construction

I _AF

Distance center of gravity trailer support load

I _AH

Distance rear axle trailer support load

I _AV

Distance front axle trailer support load

Claims (11)

A method of determining a trailer support load (G _A ) exerted on the vehicle by a trailer load attached to a vehicle (1), comprising the steps of: - determining an unloaded vehicle position before the trailer load is coupled to the vehicle (1), - docking the towing load, which exerts a trailer support load (G _A ) on the vehicle (1), to the vehicle (1), - determining a loaded vehicle position after the towing load has been coupled to the vehicle (1), - determining a vehicle position change from the unloaded vehicle position and the loaded vehicle attitude, and - determining the trailer support load (G _A ) exerted by the trailer load on the vehicle (1) from the vehicle attitude change. Method according to Claim 1 characterized by measuring at least one spring travel (ΔW _VL , ΔW _VR , ΔW _HL , ΔW _HR , ΔW _V , ΔW _H ) of an axle (V, H) of the vehicle (1) to determine the unloaded vehicle attitude and the loaded vehicle attitude. Method according to Claim 1 or 2 characterized by measuring spring travel (ΔW _V ) on the front axle (V) of the vehicle (1) and measuring spring travel (ΔW _H ) on the rear axle (H) of the vehicle (1) to increase the unloaded vehicle attitude and the loaded vehicle attitude determine. Method according to one of the preceding claims, characterized by measuring spring paths (ΔW _VL , ΔW _VR , ΔW _HL , ΔW _HR ) on each wheel (4, 5) of the vehicle (1) to determine the unloaded vehicle position and the loaded vehicle position. Method according to one of the preceding claims, characterized by measuring a pitch angle (a) of a longitudinal inclination of the vehicle (1) in order to determine the unloaded vehicle position and the loaded vehicle position. Method according to one of Claims 2 - 5 characterized by using calibrated support load characteristics of the spring travel (ΔW _VL , ΔW _VR , ΔW _HL , ΔW _HR , ΔW _V , ΔW _H ) and pitch angle (a), respectively, to account for friction in the axles of the vehicle. Device for determining a trailer support load (G _A ) which is exerted on the vehicle (1) by a trailer load attached to a vehicle (1), comprising: - at least one transducer (2, 3), which is used to determine a vehicle position of the vehicle (G) 1), and - a computing unit (6) which is connected to the at least one sensor (2, 3), characterized in that the apparatus for carrying out the method according to one of Claims 1 - 6 is designed. Device after Claim 7 , characterized in that the device comprises a user guide which guides the user to perform the method according to any one of Claims 1 - 6 instructs. Device after Claim 7 or 8th characterized in that the device is connected to a display unit (7) of the vehicle and displays the determined trailer support load (G _A ) on the display unit (7). Device according to one of Claims 7 - 9 , characterized in that the at least one transducer (2, 3) comprises a spring travel sensor or a pitch angle sensor. Vehicle, characterized in that the vehicle with a device for determining a trailer support load (G _A ) according to one of Claims 7 - 10 Is provided.

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