METHOD AND DEVICE FOR SAFELY PARKING A VEHICLE

Abstract

The invention relates to a method for safely parking a vehicle, wherein the vehicle comprises at least two vehicle axles, on each of which at least one axle load sensor is arranged. The method comprises the steps of: detecting the axle loads occurring on the at least two vehicle axles with the aid of the axle load sensors (S1); determining an axle load ratio for at least one of the vehicle axles on the basis of the detected axle loads (S2); and outputting a warning if the determined axle load ratio falls below a predetermined limit value (S3). As a result, it is possibleon the basis of the on-board weighing system usually present in commercial vehiclesto warn the driver of potentially critical parking positions, in particular on downhill slopes. The invention also relates to a corresponding warning device for carrying out this method and to a vehicle comprising such a warning device.

Claims

1-13. (canceled)

14. A method for safely parking a vehicle, the vehicle comprising at least two vehicle axles, on each of which at least one axle load sensor is arranged, the method comprising the steps: detecting of the axle loads occurring on the at least two vehicle axles with the aid of the axle load sensors; determining an axle load ratio for at least one of the vehicle axles based on the detected axle loads; and outputting a warning if the determined axle load ratio is below a predetermined limit value.

15. The method according to claim 14, wherein the method is for safely parking a vehicle on a slope.

16. The method according to claim 14, wherein the warning indicates that safe parking of the vehicle is not possible and/or another parking position should be taken and/or the vehicle should be additionally secured.

17. The method according to claim 14, wherein the method is carried out only when after the vehicle is parked.

18. The method according to claim 14, wherein the method is carried out only immediately after the vehicle is parked.

19. The method according to claim 17, wherein by detecting at least one signal indicating that the vehicle has been parked, and wherein the further steps of the method being carried out as a function of the detected at least one signal.

20. The method according to claim 19, wherein the signal is outputted when the engine is switched off and/or when the ignition key is removed.

21. The method according to claim 14, wherein the axle load ratio indicates the ratio of the axle load on the at least one vehicle axle to the sum of the axle loads on the at least two vehicle axles.

22. The method according to claim 14, wherein the predetermined limit value a) is a limit value dependent on a vehicle model; and/or b) is a limit value that is independent of a current loading condition of the vehicle.

23. The method according to claim 14, wherein the at least one axle load sensor comprises a strain gauge and/or a displacement sensor.

24. The method according to claim 14, wherein the at least one vehicle axle for which a determination of the axle load ratio takes place, a) comprises a parking brake device; and/or b) is a rear axle of the vehicle.

25. The method according to claim 14, wherein determining of the predetermined limit value taking into account parking tests on slopes with known gradient.

26. The method according to claim 25, wherein the parking tests are carried out with the lowest possible load and/or the lowest possible tank content of the vehicle.

27. The method according to claim 26, wherein the lowest possible load is no load and/or the lowest possible tank contest is an empty tank.

28. A warning device for a vehicle, wherein the warning device is configured to perform a method according to claim 14.

29. A vehicle comprising at least two vehicle axles, on each of which at least one axle load sensor is arranged, and a warning device according to claim 28.

30. The vehicle according to claim 29, wherein the vehicle is a commercial vehicle.

31. The vehicle according to claim 30, wherein the commercial vehicle is a semitrailer truck.

Description

[0028] FIG. 1 shows a schematic flow diagram of a method for safely parking a vehicle according to an embodiment of the invention;

[0029] FIG. 2 shows a schematic representation of a vehicle comprising a warning device according to an embodiment of the invention; and

[0030] FIG. 3 shows exemplary axle load distributions for a vehicle with two vehicle axles for different angles of inclination and different loading conditions.

[0031] Identical or functionally equivalent elements are designated with the same reference signs in all figures and are not described separately in some cases.

[0032] FIG. 1 shows a schematic flow diagram of a method for safely parking a vehicle 1 according to one embodiment of the invention. The vehicle 1 is to comprise at least two vehicle axles, for example a front axle 1a and a rear axle 1b, on each of which at least one axle load sensor 3a, 3b is arranged. In step S1, the axle loads occurring on the at least two vehicle axles 1a, 1b are detected with the aid of the axle load sensors 3a, 3b. In the merely exemplary case of two vehicle axlesi.e. a front axle 1a and a rear axle 1bthe axle load G.sub.V occurring on the front axle 1a and the axle load G.sub.H occurring on the rear axle 1b may thus be detected in step S1.

[0033] In step S2, an axle load ratio is then determined for at least one of the vehicle axles on the basis of the detected axle loads. In the above-mentioned example, the may axle load ratio of the rear axle 1b may be determined in step S2 according to the formula G.sub.H/(G+G.sub.VH). In addition or alternatively, however, the may axle load ratio of the front axle 1a could also be determined according to the formula G.sub.V/(G+G.sub.VH). Preferably, in step S2 the axle load ratio is determined for a vehicle axle that includes a parking brake device, which is usually the rear axle 1b.

[0034] In step S3, a warning is then outputted if the determined axle load fraction falls below a predetermined, i.e. previously defined, limit value. In other words, the method may comprise comparing the determined axle load ratio with a predetermined limit value, whereby a warning may be outputted (issued) if the determined axle load ratio is less than the predetermined limit value, and preferably no warning is outputted (issued) if the determined axle load ratio is equal to or greater than the predetermined limit value.

[0035] FIG. 2 shows a schematic representation of a vehicle 1, comprising a warning device 4 according to one embodiment of the invention. In the present case, the vehicle 1 isby way of example onlya semitrailer truck (a tractor unit) without a corresponding semitrailer. The semitrailer truck is located on a slope 2 which is inclined by an angle with respect to the horizontal, i.e. rises in the opposite direction to the direction of travel of the vehicle 1 with a gradient S=tan(a).

[0036] Furthermore, the vehicle 1 comprises at least two vehicle axles, in this case a front axle 1a and a rear axle 1b, on each of which at least one axle load sensor 3a, 3b is arranged. In the present example, the axle load sensor 3a is arranged on the front axle 1a and the axle load sensor 3b is arranged on the rear axle 1b, whereby the respective vehicle axles 1a and 1b may additionally comprise further axle load sensors, for example for detecting lateral axle load distributions.

[0037] According to the invention, the vehicle 1 further comprises a warning device 4 which is designed to carry out a method as described in this document. For this purpose, the warning device 4 may be in communication with the aforementioned axle load sensors 3a and 3b via corresponding signal lines, shown in dashed lines in FIG. 2, in order to receive the axle loads detected by the axle load sensors 3a and 3b. On the basis of these axle loads, the warning device 4 may then determine an axle load ratio for at least one of the vehicle axles, e.g. the rear axle 1b, and issue a warning if the axle load ratio determined falls below a predetermined limit value, the limit value preferably being set in such a way that, if the axle load ratio exceeds this limit value, sufficient braking action may be achieved on the corresponding vehicle axle when the vehicle 1 is parked without the vehicle 1 rolling or sliding away.

[0038] FIG. 3 shows exemplary axle load distributions for a vehicle 1 with two vehicle axlesa front axle 1a and a rear axle 1bfor different angles of inclination and different loading conditions (m.sub.1 and m.sub.2). In this case, vehicle 1 is again a semitrailer truck without a semitraileras already discussed in connection with FIG. 2, and therefore, detailed referencing of all corresponding vehicle components has been omitted here.

[0039] In the case shown at the top of FIG. 3, the vehicle 1 is on a level roadway that has no incline or slope (S=0). In contrast, the case shown in the middle of FIG. 3 shows a situation in which the vehicle 1 is on a slope 2 that is inclined by =10 with respect to the horizontal, i.e. slopes down in the direction of travel of the vehicle tractor 1 with a gradient S of approximately 18%. In the case shown at the bottom of FIG. 3, the semitrailer truck is located on an even more steeply inclined roadway, which is inclined by =15 with respect to the horizontal, i.e. slopes down in the direction of travel of the vehicle train 1 with a gradient S of approximately 27%.

[0040] The values provided in the respective tables represent exemplary axle load distributions in the various inclination situations. The left column corresponds to the case of an almost empty vehicle 1 (without driver and without fuel) with a total weight of 8760 kg, while the right column pertains to the case of a vehicle 1 with a driver (75 kg) and a full tank, resulting in a corresponding total weight of 9137 kg.

[0041] As may be seen from the horizontal case (shown at the top), the axle load in this case is front-loaded due to the design-related component distribution, i.e. the center of gravity is closer to the front axle 1a than to the rear axle 1b, resulting in a greater axle load G.sub.V on the front axle 1a than on the rear axle 1b (G.sub.H<G.sub.V). As the gradient (center and bottom) increases, the direction of action of the center of gravity moves, which means that the front axle 1a is loaded more and the rear axle 1b is relieved more, which is then also reflected in the axle load ratio of the rear axle 1b, i.e. in the value G.sub.H/(G+G.sub.VH). This dropsfor the empty vehicle 1from a value of 0.3789954 in the horizontal case to 0.3656393 at an angle of inclination of 15. This trend may also be observed in the case of the loaded vehicle 1, although the overall larger axle loads G.sub.V, G.sub.H result in somewhat larger axle load shares.

[0042] Above a certain angle of inclination .sub.grenz, the static friction of the rear axle 1bin the case of a parking brake usually fitted to the rear axle 1bwould no longer be sufficient to hold the vehicle 1 on the incline 2, so that there would then be a risk of uncontrolled rolling away or sliding of the vehicle 1 without further safety measures. This is where the solution according to the invention comes into play, which warns the driver of such critical situations by issuing a warning if the axle load fraction (in this case, the rear axle 1b) falls below a predetermined threshold. This is where the solution according to the invention comes in, which warns the driver of such critical situations by issuing a warning if the axle load component (here of the rear axle 1b) falls below a predetermined limit value. As illustrated by the two exemplary cases with m.sub.1 and m.sub.2, the danger is greater in the case of a light, i.e. lightly loaded, vehicle 1, since less weight is loaded on the axles, so that the limit value is preferably set in such a way that sufficient braking effect may still be achieved on the axle even with the lightest possible vehicle.

[0043] Although the invention has been described with reference to specific embodiments, it is apparent to one skilled in the art that various modifications may be made and equivalents may be used as substitutes without departing from the scope of the invention. Consequently, the invention is not intended to be limited to the disclosed embodiments, but is intended to encom-pass all embodiments that fall within the scope of the enclosed claims. In particular, the invention also claims protection for the subject matter and features of the dependent claims independent of the claims referenced.

LIST OF REFERENCE SIGNS

[0044] 1 vehicle [0045] 1a, 1b vehicle axle [0046] 2 slope [0047] 3a, 3b axis load sensor [0048] 4 warning device