Road maintenance machine and method for controlling operation thereof

Abstract

The invention relates to a road finishing machine comprising a tractor, a material hopper arranged in front of the tractor seen in the direction of travel and configured to contain material, a screed mounted to the tractor by means of a tow arm to pivot around a tow point such that the screed can be towed behind the tractor seen in the direction of travel. The road finishing machine further comprises a control system comprising height detection means configured to detect vertical movement of the screed relative to a height reference and to generate a height signal based on the detected movement, and an adjustment cylinder connected to one of the tow arms and to the tractor and configured to adjust the height of the tow point relative to the tractor. The control system is configured to compare the height signal to a target value and to calculate a control deviation therefrom, to limit an adjustment displacement of the adjustment cylinder based on the control deviation to a maximum value, wherein the maximum value is proportional to the control deviation, and to adjust the adjustment cylinder based on the control deviation and taking into account the maximum value.

Description

Technical Field

[0001] This invention relates to a road finishing machine with an automatic leveling system, and a method for controlling the operation of such a paver. Background Technology

[0002] A road paving machine is known to include a screed for compacting paving materials (e.g., asphalt) and a tractor for towing the screed. The screed is typically mounted on the tractor for pivoting around a towing point. The height of the towing point can be adjusted, for example, by using a hydraulic cylinder. A so-called tar machine is known from DE 10 2011 001 542 A1. A leveling rod is disclosed, which is attached to the machine at the towing point. The lifting of the towing point can be adjusted by a towing point cylinder. Here, the amount of adjustment that can be made over a distance of 5 m traveled by the machine is limited to 3 mm. Furthermore, the calculated lift / lower value is only adjusted by the cylinder when it is greater than 1 mm. The disclosed control is based on the assumption that the towing point cylinder may never be adjusted more than 3 mm over a distance of 5 m traveled. Summary of the Invention

[0003] However, in some paving situations, such rigid constraints may be impractical. Therefore, the object of the present invention is to provide an improved paver and an improved method for controlling its operation, which allows for more flexible operation.

[0004] This task is solved by the road repair machine and method according to the present invention.

[0005] A road screed machine is disclosed, comprising a tractor and a material hopper positioned in front of the tractor in the direction of travel and configured to hold material. The road screed machine further includes: a screed mounted to the tractor via a drawarm for pivoting about a traction point, such that the screed can be towed behind the tractor in the direction of travel; and a control system including a height detection device and an adjusting cylinder. The height detection device is configured to generate a height signal, and the adjusting cylinder is connected to one of the drawarms and the tractor and configured to adjust the height of the traction point relative to the tractor. The control system is configured to compare the height signal with a target value to calculate a control deviation, thereby limiting the adjusting displacement of the adjusting cylinder (specifically, the implemented adjusting displacement) to a maximum value based on the control deviation, wherein the maximum value is proportional to the control deviation, and the control system is further configured to adjust the adjusting cylinder based on the control deviation and taking into account the maximum value.

[0006] Advantageously, the height detection device can be configured to detect the vertical movement of the ironing board relative to a height reference, and preferably generate a height signal based on the detection.

[0007] Line references, curb edges, edges of previously laid asphalt layers, or laser beams can be used as height references. Accordingly, height detection devices can be configured to detect the corresponding height references and include height sensors, such as sensing arms, as well as ultrasonic sensors, cameras, or laser sensors. Height detection devices with laser sensors can be configured to detect laser beams as height references and / or identify edges by generating and detecting line lasers. In particular, in the latter case, the height detection device may include its own laser source.

[0008] Alternatively or additionally, the height detection device may include one or more tilt sensors. The tilt sensors may be configured to detect the tilt of the ironing board, particularly the lateral tilt. Several tilt sensors may, for example, be configured to detect the tilt of a portion of the ironing board. When a height signal is generated based on the output of the tilt sensors, the length of the ironing board or the portion of the ironing board whose tilt is detected by the tilt sensors, particularly the length laterally defined relative to the direction of travel, can be considered. This allows the conversion of an angle signal into a height signal, preferably a vertical height signal. In particular, in embodiments where the height detection device is not configured to detect vertical movement of the ironing board relative to a height reference, the height of the ironing board can be manually controlled on one side. The height of the ironing board on the opposite side relative to the direction of travel can then be controlled by a height detection device with tilt sensors, as explained in further detail above.

[0009] Alternatively or additionally, the height detection device may include a processing unit. The processing unit may be configured to generate a height signal based on the output of one or more of the previously mentioned sensors, particularly height sensors, sensing arms, ultrasonic sensors, cameras, laser sensors, and tilt sensors. The height signal may be generated, in particular, based on the outputs of the height sensor and one or more tilt sensors, for example, by adding a height signal generated according to the explanation above.

[0010] Limiting the adjustment displacement to a maximum value proportional to the control deviation allows the maximum value to automatically adapt to the corresponding paving conditions. Simultaneously, it prevents undesirable effects of inertia in the control path, such as overshoot or excessive oscillation. Changes in the traction point may only affect the height measured by the height detection device after a delay. Without limiting the adjustment displacement, it may undesirably increase or decrease accordingly due to the longer duration of the control deviation. Furthermore, in cases of small control deviations that may be caused only by temporary and / or short-term disturbances (e.g., vibration), the adjustment displacement can also be limited sufficiently to minimize the impact on the paving outcome. Specifically, for calculating, comparing, and generating signals, the control system may include suitable electronic components. Here, individual components or parts may each perform one or more of the mentioned functions. It is conceivable that the central control system of a road finishing machine performs this function.

[0011] It is conceivable that the maximum value is defined relative to a reference value. For example, a certain extended position of the adjusting cylinder can be considered as the reference value. The reference value can be defined, for example, as an extension position 160 mm beyond the fully retracted position of the adjusting cylinder. In this case, if the adjusting displacement is limited to a maximum value of 5 mm relative to the reference value, the adjustment of the adjusting cylinder can be limited to an extension position within the range of 155 mm to 165 mm.

[0012] It can be advantageous if the reference value can be adjusted by the operator. This is particularly useful at the start of paving, for example, to provide an initial reference value. It is especially beneficial if the control system is configured to automatically adjust the reference value. For example, it can be specified that the reference value is automatically adjusted when the control system identifies it as being in a steady-state. A state where the height signal matches the target value and / or the control deviation is 0, close to 0, or less than 2 mm can be considered a steady state. In this way, the reference value can be adapted to varying extension locations.

[0013] It is conceivable that the maximum value can be obtained by multiplying the control deviation by a scaling factor (e.g., 2). The scaling factor can be adjusted, for example, by the operator of the road repair machine.

[0014] It is conceivable that an upper limit is defined for the maximum value. In this way, for example, the extension range of the adjusting cylinder can be considered, i.e., the adjusting cylinder can be prevented from extending to its end stop. The upper limit can be defined based on a reference value (in particular, the currently set reference value). For example, if the maximum possible extension position of the adjusting cylinder is 200 mm and the currently set reference value is 150 mm, the upper limit of the maximum value can be 45 mm to prevent the adjusting cylinder from stopping at its end position.

[0015] Furthermore, a method for controlling the operation of a road repair machine is disclosed. The road repair machine includes: a tractor; a material hopper positioned in front of the tractor in the direction of travel and configured to receive material; a screed mounted to the tractor via a drawarm so as to be pivotable about a traction point, allowing the screed to be towed behind the tractor in the direction of travel; and a control system having a height detection device and an adjusting cylinder connected to one of the drawarms and the tractor. The method includes: generating a height signal by the height detection device; calculating a control deviation by comparing the height signal with a target value; limiting the adjusting displacement of the adjusting cylinder to a maximum value proportional to the control deviation; calculating an adjusting signal based on the control deviation taking into account the maximum value of the adjusting displacement; and adjusting the height of the traction point by the adjusting cylinder based on the adjusting signal.

[0016] It may be advantageous if the method further includes detecting the movement of the screed plate relative to a height reference by a height detection device, wherein the height signal is preferably generated based on the detected movement of the screed plate relative to the height reference. All further explanations given above regarding the disclosed road finishing machine are applicable to the disclosed method.

[0017] As mentioned above regarding road finishing machines, limiting the adjustment displacement to a maximum value proportional to the control deviation allows the maximum value to automatically adapt to the corresponding paving conditions. Simultaneously, undesirable inertial effects in the control path, such as overshoot or excessive oscillation, can be avoided. Furthermore, in cases of small control deviations that may be caused only by temporary and / or short-term disturbances (e.g., vibration), the adjustment displacement can be sufficiently limited to minimize the impact on the paving outcome. Specifically, for calculating, comparing, or generating signals, the control system may include suitable electronic components and / or parts. Here, each individual component or part may perform one or more of the mentioned functions. It is conceivable that the central control of the road finishing machine performs these functions.

[0018] It is conceivable that the maximum value is defined relative to a reference value. As further explained above, for example, adjusting a certain extension position of a cylinder can be considered a reference value.

[0019] It can be advantageous if the reference value can be adjusted by the operator. As further explained above, this can be particularly useful at the start of paving, for example, to provide an initial reference value. It is particularly advantageous if the method includes automatic adjustment of the reference value by the control system. For example, it can be specified that the reference value is automatically adjusted when the control system detects that the reference value is in a steady state. In this way, the reference value can be adapted to varying extension locations.

[0020] It is conceivable that the maximum value is given by multiplying the control deviation by a scaling factor (e.g., 2). The scaling factor can be adjusted, for example, by the operator of the road repair machine.

[0021] It is conceivable to define an upper limit for the maximum value. As further explained above, in this way, the extension range of the cylinder can be adjusted, i.e., the cylinder can be prevented from extending to its end stop. The upper limit can be defined based on a reference value (especially the currently set reference value). Attached Figure Description

[0022] This invention relates to road repair machines and methods of the type described above. In the following, advantageous embodiments will be explained using the accompanying drawings as examples.

[0023] Figure 1 A schematic side view of a road repair machine is shown.

[0024] Figure 2A schematic perspective view of a road finishing machine during paving driven by a height reference is shown.

[0025] Figure 3 A schematic diagram of the components of the control system of the road repair machine is shown. Detailed Implementation

[0026] exist Figure 1 The diagram shows a road screed machine 1 in a schematic side view. The road screed machine 1 may include a tractor 2. The road screed machine 1 may also include a material hopper 3. Viewed in the driving direction R, the material hopper 3 may be positioned in front of the tractor 2. The material hopper 3 may also be configured to hold material 4 (see...). Figure 2 The road screed machine 1 may also include a screed 5. The screed 5 can be mounted to the tractor 2 via a drawbar 6. As shown in the embodiment, the screed 5 can be mounted to the tractor 2 so as to be able to pivot about a drawbar 7. The tractor 2 can be configured to tow the screed, preferably smoothly tow it over the asphalt layer to be compacted. The road screed machine 1 may also include an adjusting cylinder 8. The adjusting cylinder 8 can be connected to the tractor 2 on one side. The adjusting cylinder 8 can be connected to the drawbar 6 on the other side (particularly at the drawbar 7). The adjusting cylinder 8 can be configured to adjust the height of the drawbar 7 relative to the tractor 2.

[0027] exist Figure 2 In the diagram, the road repair machine 1 is shown from the front and top in a schematic perspective view. Furthermore, Figure 2 The planar surface to be paved with asphalt and height reference 9 are schematically shown. As in this embodiment, height reference 9 may be a reference line. The road finishing machine 1 may include a height detection device 10. As in this embodiment, height detection device 10 may be an ultrasonic sensor configured to detect reference line 9. Height detection device 10 may be fixed to screed 5 and / or traction arm 6. In this way, height detection device 10 may be configured to detect substantially vertical movement of screed 5 relative to height reference 9. To adjust the height of traction point 7 by adjusting cylinder 8, the road finishing machine 1 may include a control system 11, which will be referred to below. Figure 3 To explain in more detail.

[0028] Figure 3 A schematic diagram illustrating the function of control system 11 is shown. Control system 11 may include a height detection device 10. Control system 11 may also include an adjusting cylinder 8. Height detection device 10 may be configured to generate a height signal 12 based on the detection of a height reference 9. Height signal 12 may specifically represent the height of ironing plate 5 above the plane. Control system 11 may be configured to compare height signal 12 with a target value 13. Control system 11 may also be configured to calculate a control deviation 14 based on the comparison between target value 13 and height signal 12.

[0029] The control system 11 may further include a calculation unit 15. The calculation unit 15 may be configured to calculate an initial adjustment signal 16 based on the control deviation 14. Furthermore, the control system 11 may be configured to calculate a maximum value 17 based on the control deviation 14. The control system 11 may also include a limiter 18. The limiter 18 may be configured to adjust the adjustment signal 19 sent to the adjusting cylinder 8, such that the adjusted displacement 20 performed by the adjusting cylinder 8 is appropriately limited, particularly limited to the calculated maximum value 17. The limiter may be configured to generate the adjustment signal 19 based on the initial adjustment signal 18 and the maximum value 17.

[0030] During the generation of adjustment signal 19, a reference value 21 may be considered. If the reference value 21 is not considered during the generation of adjustment signal 19, then adjustment signal 19 may represent the adjustment displacement to be achieved by adjustment cylinder 8. Adjustment cylinder 8 can then be adjusted based on adjustment signal 19 by the adjustment displacement to be implemented. If reference value 21 is considered, adjustment signal 19 may represent the extended position of adjustment cylinder 8. In the latter case, adjustment cylinder 8 may be configured to achieve the desired extended position based on adjustment signal 19 sent to adjustment cylinder 8. In both variations, the adjustment displacement implemented by adjustment cylinder 8 may be limited to a maximum value of 17. The difference lies in the type of control of adjustment cylinder 8.

[0031] The maximum value 17 can be proportional to the control deviation 14, and can preferably be calculated by multiplying the control deviation 14 by a scaling factor 22. The scaling factor 22 is adjustable, particularly by the operator of the road finishing machine 1. Specifically, the maximum value 17 can, for example, be twice the control deviation 14. The reference value 21 can be adjusted by the operator. Alternatively or additionally, the control system 11 can be configured to automatically adapt to the reference value 21. For example, it is conceivable that at the start of paving drive, the reference value 21 is set by the operator and continuously and autonomously adjusted by the control system 11.

[0032] In addition to adjusting cylinder 8 Figure 3 Any of the units shown can be understood as logic units. These can be implemented as electronic circuits, software, or a combination of both. In particular, the height detection device 10 can be implemented as a combination of electronic circuits and software.

Claims

1. A road repair machine (1), comprising: Tractor (2); The material hopper (3) is positioned in front of the tractor (2) in the direction of travel (R) and is configured to hold material (4). The ironing plate (5) is mounted to the tractor (2) via a traction arm (6) so that it can pivot about a traction point (7) so that the ironing plate (5) can be towed behind the tractor (2) in the direction of travel (R); The control system (11) includes a height detection device (10) and an adjusting cylinder (8), the height detection device (10) being configured to generate a height signal (12), and the adjusting cylinder (8) being connected to one of the traction arms (6) and the tractor (2) and configured to adjust the height of the traction point (7) relative to the tractor (2), the control system (11) also including a computing unit (15) and a limiter (18). The control system (11) is configured to compare the height signal (12) with the target value (13) and thereby calculate the control deviation (14), and calculate the maximum value (17) based on the control deviation (14). The calculation unit (15) is configured to calculate the original adjustment signal (16) based on the control deviation (14). The limiter (18) is configured to generate an adjustment signal (19) based on the original adjustment signal (16) and the maximum value (17), and adjust the adjustment signal (19) sent to the adjustment cylinder (8) such that the adjustment displacement (20) of the adjustment cylinder (8) is limited to the maximum value (17) based on the control deviation (14), wherein the maximum value (17) is proportional to the control deviation (14).

2. The road repair machine according to claim 1, wherein, The height detection device (10) is configured to detect the vertical movement of the ironing board (5) relative to the height reference (9) and generate the height signal (12) based on the detection.

3. The road repair machine according to claim 1, wherein, The maximum value (17) is defined relative to the reference value (21).

4. The road repair machine according to claim 2, wherein, The maximum value (17) is defined relative to the reference value (21).

5. The road repair machine according to claim 3, wherein, The reference value (21) can be adjusted by the operator.

6. The road repair machine according to claim 4, wherein, The reference value (21) can be adjusted by the operator.

7. The road repair machine according to any one of claims 3 to 6, wherein, The control system (11) is configured to automatically adjust the reference value (21).

8. The road repair machine according to any one of claims 1 to 6, wherein, The maximum value (17) is given by multiplying the control deviation (14) by the scaling factor (22).

9. The road repair machine according to claim 8, wherein, The scaling factor (22) is adjustable.

10. The road repair machine according to any one of claims 1 to 6, wherein, Define an upper limit for the maximum value (17).

11. A method for controlling the operation of a road repair machine (1), the road repair machine (1) comprising: Tractor (2); material hopper (3), which is positioned in front of the tractor (2) in the direction of travel (R) and configured to hold material (4); ironing board (5), which is mounted to the tractor (2) via a draw arm (6) so as to be pivotable about a traction point (7) so that the ironing board (5) can be towed behind the tractor (2) in the direction of travel (R); control system (11), which has a height detection device (10) and an adjusting cylinder (8) connected to one of the draw arms (6) and the tractor (2), the control system (11) further including a computing unit (15) and a limiter (18), the method comprising: A height signal (12) is generated by the height detection device (10); The control deviation (14) is calculated by comparing the altitude signal (12) with the target value (13); The adjustment displacement (20) of the adjustment cylinder (8) is limited to a maximum value (17) that is proportional to the control deviation (14). The original adjustment signal (16) is calculated based on the control deviation (14). The adjustment signal (19) is calculated based on the maximum value (17) of the adjustment displacement (20) and the original adjustment signal (16); and The height of the traction point (7) is adjusted by the regulating cylinder (8) based on the regulating signal (19).

12. The method of claim 11, further comprising: The movement of the ironing board (5) relative to the height reference (9) is detected by the height detection device (10), wherein the height signal (12) is generated based on the detected movement of the ironing board (5) relative to the height reference (9).

13. The method according to claim 11, wherein, The maximum value (17) is defined relative to the reference value (21).

14. The method according to claim 12, wherein, The maximum value (17) is defined relative to the reference value (21).

15. The method according to claim 13, wherein, The reference value (21) can be adjusted by the operator.

16. The method of claim 14, wherein, The reference value (21) can be adjusted by the operator.

17. The method according to any one of claims 13 to 16, further comprising automatically adjusting the reference value (21) by the control system (11).

18. The method according to any one of claims 11 to 16, wherein, The maximum value (17) is given by multiplying the control deviation (14) by the scaling factor (22).

19. The method according to claim 18, wherein, The scaling factor (22) is adjustable.

20. The method according to any one of claims 11 to 16, wherein, Define an upper limit for the maximum value (17).

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