CONTROL DEVICE AND METHOD FOR IMPROVING THE MEASURING ACCURACY OF AN ON-BOARD VEHICLE AXLE LOAD MEASUREMENT SYSTEM

Abstract

A control device is for a vehicle and a method is for improving the measuring accuracy of an on-board vehicle axle load measurement system during a loading or unloading process and/or during the levelling of a stationary vehicle, wherein a wheel brake is assigned to each vehicle wheel, and wherein each wheel brake is actuatable via an on-board vehicle electronic braking system. The control device is configured to control the electronic braking system such that the latter, by the repeated engagement and/or release of at least one or more of the wheel brakes, reduces mechanical stresses within the vehicle body which impair the accuracy of the axle load measurement system. A method is for operating this control device.

Claims

1. A control device for a vehicle having a plurality of vehicle wheels, the device being for improving the measuring accuracy of an on-board vehicle axle load measurement system during at least one of loading, unloading, and levelling of a stationary vehicle, wherein a wheel brake is assigned to each vehicle wheel, and wherein each wheel brake is actuatable via an onboard vehicle electronic braking system, the control device comprising: a non-transitory computer readable storage medium having program code stored thereon; and, said program code, when executed by a processor, being configured to control the electronic braking system such that the electronic braking system, by at least one of repeated engagement and releasing of at least one or more of the wheel brakes, reduces mechanical stresses within a vehicle body which impair the accuracy of the axle load measurement system.

2. The control device of claim 1, wherein the control device is configured, during the at least one of loading, unloading, and levelling, notwithstanding the repeated engagement and/or release of at least one or more of the wheel brakes, to ensure a roll-away protection of the vehicle.

3. The control device of claim 1, wherein the control device is an integral component of the electronic braking system of the vehicle.

4. The control device of claim 1, wherein the control device is configured, upon the expiry of a pre-definable time interval, to engage at least a proportion of previously engaged wheel brakes and to release at least a proportion of the previously engaged wheel brakes.

5. The control device of claim 4, wherein the time interval, which is controlled by the control device, is adjustable to a value between 1 second and 10 minutes.

6. A control device for a vehicle having a plurality of vehicle wheels, the device being for improving the measuring accuracy of an on-board vehicle axle load measurement system during at least one of loading, unloading, and levelling of a stationary vehicle, wherein a wheel brake is assigned to each vehicle wheel, and wherein each wheel brake is actuatable via an on-board vehicle electronic braking system, the control device comprising: a hardware circuit configured to control the electronic braking system such that the electronic braking system, by at least one of repeated engagement and releasing of at least one or more of the wheel brakes, reduces mechanical stresses within a vehicle body which impair the accuracy of the axle load measurement system.

7. A method for improving measuring accuracy of an on-board vehicle axle load measurement system of a vehicle during at least one of a loading process, an unloading process and during a levelling of a stationary vehicle, wherein a wheel brake is assigned to each vehicle wheel, and wherein each wheel brake is actuatable via an on-board vehicle electronic braking system, the method comprising: a) engaging all wheel brakes prior to a commencement of the at least one of the loading process, unloading process, and the leveling of the stationary vehicle; b) on the stationary vehicle, releasing a maximum number of wheel brakes such that any independent roll-away of the vehicle, even of a fully-laden vehicle, will be prevented via the remaining engaged wheel brakes; c) finishing of a predefined time interval, which is appropriate for a reduction of mechanical stresses within at least one of a vehicle body and running gear which will compromise the accuracy of the axle load measurement system; d) engaging of at least one or more of previously released wheel brakes, wherein this proportion of wheel brakes is independently capable of ensuring roll-away protection; e) releasing of the wheel brakes which have been engaged over a longer period; f) measuring of the axle load on at least one vehicle axle; and g) repetition of steps c) to f), until the at least one of the loading process, the unloading process, and the levelling operation is terminated.

8. The method of claim 7, wherein the wheel brakes are actuated individually or in groups.

9. The method of claim 7, wherein the wheel brakes are engaged and released such that, in an event of an employment of a pneumatic braking system, compressed-air consumption is restricted within limits of necessity and in addition to the prevention of any unintentional roll-away of the vehicle a reduction of mechanical stresses is nevertheless achieved.

10. The method of claim 7, wherein the wheel brakes are engaged and released such that, in addition to the prevention of any unintentional roll-away of the vehicle, a maximum possible reduction of mechanical stresses is achieved.

11. The method of claim 7, wherein the wheel brakes which are to be released or engaged in method steps d) and e) are selected in accordance with a plausibility check of axle load values from the on-board vehicle axle load measurement system which is executed during or after process step c).

12. The method of claim 7, wherein the predefined time interval varies between 1 second and 10 minutes, in accordance with a speed of load variations associated with the at least one of the loading process, the unloading process, and the levelling operation.

13. The method of claim 7, wherein at least one wheel brake remains engaged at any time during the at least one of loading process, unloading process, and during the levelling of the vehicle.

14. The method of claim 13, wherein all the wheel brakes on at least one vehicle axle remain engaged, in order to prevent any oblique pull of the vehicle in relation to a longitudinal axis of the vehicle.

15. The method of claim 7, wherein a transition between the engaged or released state of each wheel brake, or vice versa, is executed softly rather than abruptly.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0036] The invention will now be described with reference to the drawings wherein:

[0037] FIG. 1 shows a schematic overhead view of a vehicle with a control device according to the disclosure; and,

[0038] FIG. 2 shows a schematic flow diagram of the method according to the disclosure, employing the control device according to FIG. 1.

DETAILED DESCRIPTION

[0039] The vehicle 10 represented in FIG. 1, for exemplary purposes only, is configured here as a tractor unit 12 having a coupled semi-trailer 14. Alternatively, the vehicle 10 can also be a heavy goods vehicle, with or without a trailer vehicle. Here, the tractor unit 12 includes two axles A.sub.1, A.sub.2, and the semi-trailer 14 is equipped with three axles A.sub.3, A.sub.4, A.sub.5. The tractor unit 12 is equipped with a drive unit 20, which is configured as a drive motor and which, via a down-circuit gearbox 22, a differential 26 and a take-off shaft 24, can drive the second axle A.sub.2 of the tractor unit 12.

[0040] Two wheels R.sub.1, R.sub.2 are arranged on the first axle A.sub.1 of the tractor unit 12, and two wheels R.sub.3, R.sub.4 are arranged on the second axle A.sub.2. The semi-trailer 14, on the first axle A.sub.3 thereof, includes the two wheels R.sub.5, R.sub.6, the second axle A.sub.4 includes the two wheels R.sub.7, R.sub.8, and the third axle A.sub.5 includes the two wheels R.sub.9, R.sub.10. The odd-numbered wheels R.sub.1, R.sub.3, R.sub.5, R.sub.7, R.sub.9 are arranged to the left, in relation to the longitudinal axis 18 of the vehicle 10, whereas the even-numbered wheels R.sub.2, R.sub.4, R.sub.6, R.sub.8, R.sub.10 are arranged to the right, in relation to the longitudinal axis 18 of the vehicle. Accordingly, the axle positions of the ten wheels R.sub.1, . . . , R.sub.10on the five vehicle axles A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5 are clearly defined. The forward direction of travel 16 is indicated by an arrow.

[0041] In the region of the tractor unit 12, the vehicle 10 is equipped with an on-board vehicle axle load measurement system 30 (OnBoard Weighing-System; OBW-System for short), via which axle loads acting on the individual axles A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5 are measurable. From the measured individual axle loads, via the axle load measurement system 30, an overall axle load of the vehicle 10 is calculable from the sum of the individual axle loads. The vehicle 10 can include, for example, electronically controlled air suspension, conventional steel-sprung axles, or a combination of the two.

[0042] The vehicle 10 is further equipped with an electronic braking system 36 and an on-board computer 40. Exactly one wheel brake B.sub.1, . . . , B.sub.10, which is pneumatically or hydraulically actuatable, is assigned to each vehicle wheel R.sub.1, . . . , R.sub.10 of the vehicle 10. Preferably, each of these wheel brakes B.sub.1, . . . , B.sub.10, under the control of the electronic braking system 36, can be individually engaged or released. Although, in the interests of clarity, the pneumatic or hydraulic hoses required for this purpose are not represented in FIG. 1, the layout thereof will be sufficiently known to a person skilled in this field.

[0043] The vehicle 10 is further equipped with a control device 50 according to the disclosure, which is employed for improving the accuracy of the ascertainment of axle loads by the on-board vehicle axle load measurement system 30, particularly during loading or unloading and/or during a levelling operation of the vehicle 10. The electronic braking system 36 of the vehicle 10 is actuatable and/or regulable or controllable by the control device 50, wherein the exchange of data between these two units is executed via a bidirectional data line 52. By way of deviation from the representation according to FIG. 1, the electronic braking system 36 and the control device 50 can also be entirely arranged within the tractor unit 12, or can be functionally distributed between the semi-trailer 14 and the tractor unit 12.

[0044] By the repeated release or engagement of a specific number of wheel brakes B.sub.1, . . . , B.sub.10on the axles A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5 of the stationary vehicle 10 during a loading or unloading process or during a levelling operation, under the constant monitoring of the control device 50, mechanical stresses, particularly in the vehicle body and/or in the running gear, can be reduced to a substantial extent. As mechanical stresses of this type customarily corrupt axle load measurement values which are delivered by an axle load measurement system 30, the accuracy of axle load measurement values from the axle load measurement system 30 can be considerably improved via the control device 50 according to the disclosure.

[0045] For reasons of safety, at no time during the loading or unloading process and/or during the levelling operation is the number of wheel brakes B.sub.1, . . . , B.sub.10 which are simultaneously released sufficiently large such that roll-away protection of the vehicle 10 is no longer ensured. Consequently, the vehicle 10 cannot be unintentionally set in forward motion or rotary motion.

[0046] The control device 50 can optionally be configured as an integral and functional component of the electronic braking system 36 of the vehicle 10, as a result of which a simpler and more cost-effective configuration is provided.

[0047] An exclusively hardware-based circuit of the control device 50 can be embodied, for example, in the form of a programmable logic gate arrangement. An at least partially software-based solution can be embodied, for example, in the form of a program for ensuring the repeated engagement or release of specific wheel brakes B.sub.1, . . . , B.sub.10 further to the expiry of a predefined time interval during a loading and unloading process and/or during a levelling operation by the method according to the disclosure in a stationary vehicle 10. The program is executable, either in an electronic memory of the control device 50 and/or in an electronic memory of the electronic braking system 36.

[0048] The axle load measurement system 30, the electronic braking system 36, the control device 50 and the on-board computer 40 of the vehicle 10 are respectively coupled via an unrepresented bidirectional digital data link, such as a CAN bus system or similar, and are thus capable of comprehensive mutual communication. The same applies to unrepresented sensors which are assigned to the above-mentioned systems.

[0049] FIG. 2 shows a schematic flow diagram for the operation of the method proposed herein, by the employment of the control device 50 according to FIG. 1. This method is intended, during a loading or unloading process and/or during a levelling operation of the vehicle 10 according to FIG. 1, to execute the most effective possible reduction of mechanical stresses, particularly in the region of the vehicle body or running gear, as these mechanical stresses can result in a corruption of axle load measurement values from the on-board vehicle axle load measurement system, and thus of the accuracy of the determinable value of the current overall weight of the vehicle.

[0050] Once the vehicle 10, for example, has achieved its intended loading position or unloading position on a loading ramp and is stationary, in a first process step a), prior to the commencement of a loading or unloading process and/or prior to the commencement of a levelling operation, all the wheel brakes B.sub.1, . . . , B.sub.10 are engaged, such that these execute a braking action on the assigned vehicle wheels R.sub.1, . . . , R.sub.10.

[0051] According to a second process step b), prior to the commencement of the loading or unloading process and/or prior to the commencement of a levelling operation, the wheel brakes B.sub.1, . . . , B.sub.10 are released to a maximum number such that, via the remaining engaged wheel brakes B.sub.1, . . . , B.sub.10, any unintentional roll-away of the vehicle 10 is prevented, even in the event of a fully-laden vehicle 10.

[0052] In the subsequent third process step c), the expiry of a predefined time interval is awaited which is appropriate for reducing mechanical stresses within the vehicle body and/or running gear which impair the accuracy of the axle load measurement system 30.

[0053] The above-mentioned time interval can range, for example, from 1 second to 10 minutes. It can vary, for example, in accordance with the speed of load variations associated with a loading or unloading process and/or with a levelling of the vehicle. The greater a load variation, the longer the decay time of any resulting torsion, oscillations or movements in the vehicle, and the longer the time until the release or engagement of further wheel brakes B.sub.1, . . . , B.sub.10 can be permitted without compromising the accuracy of axle load measurement.

[0054] Thereafter, in a fourth process step d), the engagement of at least one or more of the previously released wheel brakes B.sub.1, . . . , B.sub.10 is executed, wherein this proportion of wheel brakes B.sub.1, . . . , B.sub.10 is independently capable of ensuring roll-away protection or preventing any unintentional movements of the vehicle 10.

[0055] In the subsequent fifth process step e), the release of those wheel brakes B.sub.1, . . . , B.sub.10 which have been engaged over a longer period is executed. As a result of this overlap of brake actuation, a seamless braking action on the wheel brakes B.sub.1, . . . , B.sub.10 is ensured.

[0056] Thereafter, in a sixth process step f), a stress-relieved measurement of the axle load on at least one of the vehicle axles A.sub.1, A.sub.2, A.sub.3, A.sub.4, A.sub.5 is executed.

[0057] According to a seventh process step g), process steps c) to f) are repeated until such time as the loading or unloading process and/or the levelling operation is fully terminated (process step: stop).

[0058] According to the method, the wheel brakes B.sub.1, . . . , B.sub.10 are engaged and released such that, in addition to the prevention of any unintentional movement of the vehicle, a maximum possible reduction of mechanical stresses, particularly in the vehicle body and in the running gear, is simultaneously achieved.

[0059] Via the axle load measurement system, axle loads are preferably measured further to the expiry of the time interval in the third process step c) on the grounds that, by this time, mechanical stresses and oscillations which impair measurements will have substantially decayed.

[0060] Wheel brakes B.sub.1, . . . , B.sub.10 which are to be released or engaged according to process steps d) and e) can be selected, for example, in accordance with the outcome of a plausibility check of axle load values from the on-board vehicle axle load measurement system which, in particular, is executed during or after the third process step c). In the context of this plausibility check, the axle load measurement system executes a check as to whether individual axle load measurement values lie so far outside a predefined error interval or expectation interval that a measuring error associated with mechanical stresses within the vehicle body, mechanical oscillations, an improper operation, sensor errors or similar is to be assumed. By a comparison of the outcome of plausibility checks for two process sequences, preferably executed in immediate succession, it can be ascertained whether any improvement in the accuracy of axle load measurement values from the axle load measurement system has occurred. If this is not the case, an improvement in the accuracy of axle load measurement values can be achieved by the release or engagement of the wheel brakes B.sub.1, . . . , B.sub.10, controlled by the control device 50, employing the electronic braking system 36.

[0061] The length of the time interval according to the third process step c), the expiry of which is awaited prior to any further release or engagement of wheel brakes on the axles, can also be varied in accordance with the outcomes of plausibility checks within the predefined margins of 1 second and, for example, 10 minutes. This can be executed additionally or alternatively to the variation of the time interval in accordance with the speed of load variations associated with the loading and unloading process and/or with a levelling operation of the vehicle.

[0062] Regardless of the outcomes of optional plausibility checks, at least one wheel brake will remain engaged at any time, wherein preferably two wheel brakes on the same vehicle axle are respectively maintained in a braking state, in order to prevent any oblique pull of the vehicle during a loading or unloading process, or during a levelling operation.

[0063] The transition between an engaged and released state of a wheel brake, or vice versa, is not executed abruptly, but with a temporal overlap. In the context of the present description, this signifies that a braking force is not increased abruptly, that is, within a short time interval of less than one second, from 0% to 100% or, conversely, is not reduced from 100% to 0%. Instead, it is provided that the temporal braking force characteristic, for example, assumes a uniformly ramped profile, that is, increases linearly on one wheel brake and decreases linearly on the other wheel brake, for example on the same vehicle axle. In general, however, this type of actuation of wheel brakes B.sub.1, . . . , B.sub.10 is only possible in the case of hydraulic brakes, but is not achievable in pneumatic brakes.

[0064] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

LIST OF REFERENCE SYMBOLS (PART OF DESCRIPTION)

[0065] 10 Vehicle [0066] 12 Tractor vehicle, tractor unit [0067] 14 Trailer vehicle, semi-trailer [0068] 16 Forward direction of travel [0069] 18 Longitudinal axis of the vehicle [0070] 20 Drive unit, drive motor [0071] 22 Gearbox [0072] 24 Take-off shaft [0073] 30 Axle load measurement system of the vehicle [0074] 36 Electronic braking system [0075] 40 On-board computer [0076] 50 Control device [0077] 52 Data line [0078] 70 Flow diagram [0079] a)-g) Process steps [0080] A.sub.1, A.sub.2 Vehicle axles, axles of tractor vehicle [0081] A.sub.3, A.sub.4, A.sub.5 Vehicle axles, axles of trailer vehicle [0082] R.sub.1, . . . , R.sub.10 Vehicle wheels [0083] B.sub.1, . . . , B.sub.10 Wheel brakes