METHOD FOR CONTROLLING A ROAD FINISHING MACHINE WITH A WHEEL GEAR AND ROAD FINISHING MACHINE WITH A WHEEL GEAR

Abstract

The disclosure relates to a method for controlling a road finishing machine with a material bunker for receiving paving material, a screed for compressing the paving material, a drivable rear wheel and a drivable front wheel. A rotational speed of the rear wheel of the road finishing machine is measured. Moreover, a travel speed of the road finishing machine is measured. A target driving torque of the front wheel of the road finishing machine is calculated based on the measured rotational speed of the rear wheel and the measured travel speed of the road finishing machine. Then, an actual driving torque of the front wheel is adjusted to the calculated target driving torque. The disclosure also relates to a road finishing machine.

Claims

1. A method for controlling a road finishing machine having a material bunker for receiving paving material, a screed for compressing paving material, a drivable rear wheel, and a drivable front wheel, the method comprising: measuring a rotational speed of the rear wheel; measuring a travel speed of the road finishing machine; calculating a target driving torque of the front wheel based on the measured rotational speed of the rear wheel and the measured travel speed of the road finishing machine; and adjusting an actual driving torque of the front wheel to the calculated target driving torque.

2. The method according to claim 1 wherein the travel speed of the road finishing machine is measured with a travel speed sensor unit provided at the road finishing machine and comprising at least one radar sensor.

3. The method according to claim 2 wherein a direction of detection of the at least one radar sensor is inclined downward with respect to a horizontal plane.

4. The method according to claim 2 wherein the travel speed sensor unit comprises two radar sensors including a first radar sensor being arranged at the road finishing machine facing forward in the direction of travel, and a second radar sensor being arranged at the road finishing machine facing rearward in the direction of travel.

5. The method according to claim 1 wherein calculating the target driving torque comprises: determining an actually transmitted driving torque of the rear wheel based on the measured rotational speed of the rear wheel and the measured travel speed of the road finishing machine; and setting the target driving torque of the front wheel to be proportional to the determined actually transmitted driving torque of the rear wheel.

6. The method according to claim 5 wherein determining the actually transmitted driving torque of the rear wheel comprises: determining a slip of the rear wheel based on the measured rotational speed of the rear wheel and the measured travel speed; and determining the actually transmitted driving torque of the rear wheel corresponding to the determined slip of the rear wheel by means of a stored data record.

7. The method according to claim 6 wherein the stored data record is a characteristic curve diagram.

8. The method according to claim 1 wherein the vehicle includes two drivable rear wheels, wherein measuring the rotational speed of the rear wheel comprises measuring rotational speed of each rear wheel, and wherein the target driving torque of the front wheel of the road finishing machine is determined based on a smaller one of the rotational speeds of the rear wheels.

9. A road finishing machine comprising: a material bunker for receiving paving material; a screed for compressing paving material; a drivable rear wheel; a drivable front wheel; a wheel sensor unit for measuring a rotational speed of the rear wheel; a travel speed sensor unit for measuring a travel speed of the road finishing machine; and a control unit configured to: calculate a target driving torque of the front wheel based on the measured rotational speed of the rear wheel and the measured travel speed of the road finishing machine; and adjust an actual driving torque of the front wheel to the calculated target driving torque.

10. The road finishing machine according to claim 9 wherein the travel speed sensor unit comprises at least one radar sensor.

11. The road finishing machine according to claim 10 wherein a direction of detection of the at least one radar sensor is inclined downward with respect to a horizontal plane.

12. The road finishing machine according to claim 9 wherein the travel speed sensor unit comprises two radar sensors including a first radar sensor arranged at the road finishing machine facing forward in the direction of travel, and a second radar sensor arranged at the road finishing machine facing rearward in the direction of travel.

13. The road finishing machine according to claim 9 wherein the control unit is, when calculating the target driving torque, configured to: determine an actually transmitted driving torque of the rear wheel based on the measured rotational speed of the rear wheel and the measured travel speed of the road finishing machine; and set the target driving torque to be proportional to the determined actually transmitted driving torque of the rear wheel.

14. The road finishing machine according to claim 13 wherein the control unit is, when determining the actually transmitted driving torque of the rear wheel, configured to: determine a slip of the rear wheel based on the measured rotational speed of the rear wheel and the measured travel speed; and determine the actually transmitted driving torque of the rear wheel corresponding to the determined slip of the rear wheel by means of a data record stored in a characteristic curve diagram memory of the road finishing machine.

15. The road finishing machine according to claim 9 further comprising another drivable rear wheel, wherein the wheel sensor unit is configured to measure rotational speed of the other rear wheel; and the control unit is configured to determine the target driving torque of the front wheel based on a smaller one of the measured rotational speeds of the rear wheels.

16. A road finishing machine comprising: a material bunker for receiving paving material; a screed for compressing paving material; first and second drivable rear wheels; a drivable front wheel; first and second wheel sensor units for measuring rotational speed of the first and second rear wheels, respectively; a travel speed sensor unit for measuring a travel speed of the road finishing machine; and a control unit configured to: calculate a target driving torque of the front wheel based on a smaller one of the measured rotational speeds of the rear wheels and the measured travel speed of the road finishing machine; and adjust an actual driving torque of the front wheel to the calculated target driving torque.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 shows a schematic representation of a road finishing machine according to the disclosure;

[0022] FIG. 2 shows a schematic representation of how the control unit is embedded into the systems of a road finishing machine according to the disclosure;

[0023] FIG. 3 shows a schematic representation of a travel speed sensor unit of a road finishing machine according to the disclosure according to an embodiment with two radar sensors; and

[0024] FIG. 4 shows a flowchart for illustrating the determination of the target driving torque for the front wheel according to an embodiment of the method according to the disclosure.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a road finishing machine 1 according to the disclosure. It comprises, in the paving direction F at the front, a material bunker 2 for receiving paving material. At the rear in the paving direction F, a screed 3 is attached to the road finishing machine 1 (e.g., to a body of the road finishing machine) for compressing the paving material. The road finishing machine 1 comprises a chassis 4 and a control platform 5 attached thereon with operational controls 6 for controlling the road finishing machine 1. The road finishing machine 1 according to the shown embodiment comprises two drivable rear wheels 10. In the paving direction F in front of the rear wheels 10, the road finishing machine 1 comprises two drivable front wheels 12. The rear wheels 10 may be drivable together or separately. The front wheels 12, too, may be drivable together or separately. The shown road finishing machine 1 comprises a second pair of front wheels 14 for further stabilization. This pair may be drivable or not drivable, or it may be completely omitted.

[0026] In the embodiment shown in FIG. 2, the two rear wheels 10 of the road finishing machine 1 are arranged along a common axis, and each has a separate power plant A1, A2, for example hydraulic motors. The pair of drivable front wheels 12, too, is arranged along a common axis and drivable separately each via a separate power plant A3, A4. Here, it is also possible to employ hydraulic motors. The power plants A1, A2, A3, A4 are each driven by a motor M of the road finishing machine 1. If the power plants A1, A2, A3, A4 are designed as hydraulic motors, between the motor M and the respective power plants A1, A2, A3, A4, one or several hydraulic pumps P1, P2 may be connected. These are driven by the motor M and in turn drive one or several ones of the power plants A1, A2, A3, A4. In the shown embodiment, two hydraulic pumps P1, P2, are provided, wherein a first hydraulic pump P1 drives the power plants A1, A2, of the rear wheels 10, and a second hydraulic pump P2 drives the power plants A3, A4 of the front wheels 12.

[0027] At each of the rear wheels 10, a wheel sensor unit S1, S2 is provided for measuring the rotational speed of the associated rear wheel 10. It is also conceivable that a wheel sensor unit S1, S2 is only provided at one rear wheel 10.

[0028] Moreover, the road finishing machine 1 according to the disclosure comprises a travel speed sensor unit 20 for measuring a travel speed of the road finishing machine 1. Such a travel speed sensor unit 20 is represented in FIG. 3 in further detail. Advantageously, the travel speed sensor unit 20 comprises at least one radar sensor 22. According to the advantageous embodiment shown in FIG. 3, the travel speed sensor unit 20 comprises two radar sensors 22. These may be advantageously attached to a bottom side of the chassis 4 of the road finishing machine 1. It is also conceivable to attach the travel speed sensor unit 20 laterally to the road finishing machine 1. The operation of the radar sensors 22 is based on utilizing the Doppler effect. The radar sensors 22 are able to emit electromagnetic radiation in a direction of detection D. As is shown in FIG. 3, the directions of detection D of the radar sensors 22 are attached to the road finishing machine inclined downwards with respect to a horizontal plane at an angle Φ. This ensures that the emitted electromagnetic radiation is reflected by the ground 30 on which the road finishing machine 1 is moving. The reflected radiation is then detected again by the respective radar sensor 22. In the process, the frequency of the detected radiation is measured. From the difference of the frequency of the detected electromagnetic radiation to the known frequency of the originally emitted electromagnetic radiation, the travel speed of the road finishing machine 1 may be determined with the assistance of the known angle of inclination Φ of the direction of detection D of the radar sensor 22. If two radar sensors 22 are provided, as is shown in FIG. 3, the measuring accuracy may be increased and the measurement may become more independent of any unevenness of the ground. To this end, one may for example average the obtained measured values.

[0029] The measured values of the wheel sensor units S1, S2 of the rear wheels 10 and the measured value of the travel speed sensor unit 20 are supplied to a control unit 40 via corresponding data lines 42, 44, 45 shown in FIG. 2. Based on the measured rotational speed of at least one rear wheel 10 and the measured travel speed of the road finishing machine 1, the control unit 40 calculates a target driving torque. This target driving torque is emitted as target driving torque for adjusting an actual driving torque of the front wheel 12 via control lines 46, 48 to the power plant A3, A4 of at least one front wheel 12. As is shown in FIG. 2, the target driving torque may also be emitted to both front wheels 12 or their power plants A3, A4.

[0030] FIG. 4 illustrates more in detail how the control of the actual driving torque of the at least one front wheel 12 is effected based on the measured rotational speed of the at least one rear wheel 10 and the measured travel speed of the road finishing machine 1. First, in step 110, the slip of the respective rear wheel 12 is determined from the rotational speed of the rear wheel 10 and the travel speed of the road finishing machine 1. If the rotational speeds of two rear wheels 10 are determined, as is shown in FIG. 2, the smaller determined value may be used for step 110 and the further process. In step 120, an actually transmitted driving torque of the rear wheel 12 corresponding to the slip of the rear wheel 12 is read out from a stored data record. In step 130, the target driving torque of the front wheel 12 is set. In the process, the target driving torque of the at least one front wheel 12 is obtained by multiplication of the actually transmitted driving torque of the rear wheel 10 read out from the data record with a proportionality constant. As was already described, in step 140 the actual driving torque of the at least one front wheel 12 is adjusted to the calculated target driving torque. This is done by outputting the actual driving torque from the control unit 40 via the control lines 46, 48 to the corresponding drive unit A3, A4 of the at least one front wheel 12. The drive units A3, A4 may comprise a corresponding control mechanism which is designed to adjust the actual driving torque of the corresponding front wheel 12 to the target driving torque provided by the control unit 40.

[0031] It is conceivable that the stored data record may be adapted or re-entered by a user. This may be done, for example, via the operational controls 6 of the road finishing machine. It is also conceivable that an operator may adapt, preferably also via the operational controls 6, the proportionality constant used in step 120.

[0032] As one skilled in the art would understand, any of the above described units (e.g., wheel sensor units S1, S2, travel speed sensor unit 20, control unit 40) or other components may include suitable hardware and software, such as one or more processors (e.g., one or more microprocessors, microcontrollers and/or programmable digital signal processors) in communication with, or configured to communicate with, one or more storage devices or media including computer readable program instructions that are executable by the one or more processors so that the unit or other component may perform particular algorithms represented by the functions and/or operations described herein. Any of the above described units or other components may also, or instead, include one or more application specific integrated circuits, programmable gate arrays or programmable array logic, programmable logic devices, or digital signal processors.

[0033] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosure. In that regard, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the disclosure.