SCREED ASSEMBLY WITH AUTOMATIC START-STOP SYSTEM

Abstract

The disclosure relates to a screed assembly for use at a road finisher. This comprises a control unit, a first compacting device and a second compacting device, which is arranged in a first direction behind the first compacting device. The disclosure is characterized in that the control unit is configured to activate and/or deactivate the second compacting device in a delayed manner relative to the first compacting device by a time period, which is unequal to zero. The disclosure furthermore related to a method for operating a screed assembly for use at a road finisher. This comprises the following steps: activating and/or deactivating a first compacting device of the screed assembly, activating and/or deactivating a second compacting device of the screed assembly, which is arranged in direction of travel of the road finisher behind the first compacting device, after expiration of a predeterminable time period, which is unequal to zero.

Claims

1. A screed assembly for use at a road finisher, the screed assembly comprising: a control unit; a first compacting device; and a second compacting device, which is arranged in a first direction behind the first compacting device; wherein the control unit is configured to activate and/or deactivate the second compacting device in a delayed manner relative to the first compacting device by a time period, which is unequal to zero.

2. The screed assembly according to claim 1 wherein the screed assembly comprises a first screed segment and a second screed segment, wherein the second screed segment is arranged in the first direction behind the first screed segment, and wherein the first screed segment comprises the first compacting device and the second screed segment comprises the second compacting device.

3. The screed assembly according to claim 1 further comprising a sensor unit configured to detect an installation start and/or an installation end.

4. The screed assembly according to claim 3 wherein the sensor unit comprises a temperature sensor, a pyrometer, an infrared sensor, an ultrasonic sensor and/or a path sensor.

5. A road finisher comprising the screed assembly according to claim 1 and a tractor, which is configured to tow the screed assembly.

6. The road finisher according to claim 5 wherein the first direction corresponds to a direction of travel of the road finisher.

7. The road finisher according to claim 5 wherein the control unit is configured to calculate the time period based on a driving speed of the road finisher.

8. The road finisher according to claim 6 wherein a distance in the direction of travel of the road finisher defined between the first and second compacting devices is provided, and the time period corresponds to a time required by the road finisher to cover a distance, the length of which corresponds to the distance between the first and second compacting devices, with a driving speed.

9. The road finisher according to claim 5 wherein the control unit is provided at the tractor.

10. A method for operating a screed assembly for use at a road finisher, the method comprising: activating and/or deactivating a first compacting device of the screed assembly; activating and/or deactivating a second compacting device of the screed assembly, which is arranged in a direction of travel of the road finisher behind the first compacting device, after expiration of a predeterminable time period, which is unequal to zero.

11. The method according to claim 10 wherein the time period is calculated based on a driving speed of the road finisher.

12. The method according to claim 10 wherein the time period is calculated based on a distance defined in the direction of travel of the road finisher between the compacting devices.

13. The method according to claim 10 wherein an installation start and/or an installation end are/is detected by a sensor unit.

14. The method according to claim 10 wherein an installation start and/or an installation end are/is detected by means of a temperature difference.

15. The method according to one of the claim 10 wherein the first compacting device is provided at a first screed segment of the screed assembly and the second compacting device is provided at a second screed segment of the screed assembly, which is arranged in the direction of travel of the road finisher behind the first screed segment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows a road finisher with a screed assembly according to the disclosure;

[0029] FIG. 2 shows a schematic side sectional view of a screed assembly with two screed segments, each having a plurality of compacting devices;

[0030] FIGS. 3A and 3B show schematically the connections between a control unit and compacting devices of two screed segments according to two different embodiments;

[0031] FIG. 4 is a schematic presentation of two screed segments in top view from above in order to explain distances; and

[0032] FIG. 5 is a schematic presentation of two screed segments in top view from above.

DETAILED DESCRIPTION

[0033] As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary and that various and alternative forms may be employed. The figures are not necessarily to scale. Some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.

[0034] FIG. 1 shows a road finisher 1 comprising a screed assembly 2 and a tractor 3. The tractor may, for example, be connected to the screed assembly 2 by tension arms 4. Thereby, the screed assembly 2 may be pulled floating and may, thus, smooth and compact an asphalt layer to be laid. In FIG. 1, moreover, a driving direction F is shown, in which the road finisher 1 moves.

[0035] In FIG. 2, it can be seen that the screed assembly 2 comprises a first screed segment 5 and a second screed segment 6. The second screed segment 6 is arranged in the direction of travel F behind the first screed segment 5, i.e., the first screed segment 5 always reaches an installation section to be worked before the second screed segment 6. The screed assembly 2 may for example be an extendable screed. In the present embodiment, the first screed segment 5 is non-extendable and the second screed segment 6 is extendable. However, it is conceivable that the first screed segment is extendable and the second screed segment 6 is non-extendable. In a further alternative, both screed segments 5, 6 may be extendable. To a person skilled in the art, it is common that extendable screed segments 5, 6 are extendable in a lateral direction essentially perpendicular to the direction of travel of the road finisher 1. Referring to FIG. 2, this would correspond to an extension perpendicular to the drawing plane. In the present embodiment, the first screed segment 5 as well as the second screed segment 6 comprise a plurality of compacting devices 5a, 5b, 5c, 6a, 6b, 6c. The first screed segment 5 comprises a first tamper 5a, a first vibration unit 5b, as well as a first pressure bar set 5c. The second screed segment 6 comprises a second tamper 6a, a second vibration unit 6b, as well as a second pressure bar set 6c. The first pressure bar set 5c as well as the second pressure bar set 6c may comprise one or more pressure bars. It is also conceivable that both screed segments 5 and 6 each comprise only one or more of such compacting devices 5a, 5b, 5c, 6a, 6b, 6c. Also different configurations of the individual screed segments 5, 6 are conceivable.

[0036] In the present embodiment, all of said compacting devices 5a, 5b, 5c, 6a, 6b, 6c, except the pressure bar set 6c, may be regarded as first compacting device according to the disclosure. Analogously, all of said compacting devices 5a, 5b, 5c, 6a, 6b, 6c, except of the tamper 5a, may be regarded as second compacting device according to the disclosure. According to the disclosure, the screed segments 5, 6 as well as the compacting devices 5a, 5b, 5c, 6a, 6b, 6c pass an installation start 7 one after the other. The installation start 7 may, for example, be defined by an edge 8, which is provided at an already laid asphalt layer 9. In cases, in which an already laid installation layer 9 is not yet available, for example an aid, such as a wooden beam may be used for applying the screed assembly 2. The installation start 7 is shown in FIG. 2 in different positions 7a, 7b, 7c, 7d relative to the screed assembly 2.

[0037] Before starting the installation run, the tractor 3 and, consequently, the screed assembly 2 are positioned in a way that a compacting device 5a, 5b, 5c, 6a, 6b, 6c located furthest in the front in the direction of travel F, in the present embodiment the tamper 5a, is arranged at the installation start 7. In FIG. 2, this corresponds to the positioning 7a. Thereby, the screed assembly 2 may essentially be applied to the already laid asphalt layer 9 or to the aid.

[0038] According to the present disclosure, with the start of the installation run, an operator of the road finisher 1 may now initialize the activation of the compacting devices 5a, 5b, 6c, 6a, 6b, 6c, for example by pressing a button. Then, the tamper 5a is activated first. This may, for example occur directly after the initialization, or when the tractor 3 starts to move. After expiration of a predetermined time period T, without further intervention by the operator, the vibration unit 5b is activated. In FIG. 2, this may correspond to the positioning 7b. Analogously to this, the further compacting devices 5a, 5b, 5c, 6a, 6b, 6c are successively activated. The time period T is thereby selected such that the respective compacting device 5a, 5b, 5c, 6a, 6b, 6c is activated when the installation start 7 is passed.

[0039] If the screed segments 5, 6 are arranged next to one another in alignment, also the respective compacting devices may be arranged in alignment with one another (see FIG. 5). The compacting devices aligned with one another may then each be activated simultaneously, i.e., firstly, the compacting devices 5a and 6a are simultaneously activated, then the compacting devices 5b and 6b and finally, the compacting devices 5c and 6c. Aligning compacting devices may, for example, be provided in the following configurations: it is conceivable that both screed segments 5, 6 are provided in one and the same basic screed. It is furthermore conceivable that one of the screed segments 5, 6 is provided on a rigid basic screed and the other on a rigid or extendable broadening and/or attachment part attached to this basic screed. In addition, one of the screed segments 5, 6 may be provided on an extendable basic screed and the other on a broadening and/or attachment part attached thereto.

[0040] In a further alternative, it is conceivable that for example to facilitate a control circuit, the compacting devices 5a, 5b, 5c, 6a, 6b, 6c of a respective screed segment 5, 6 can only be activated together. In this case, the compacting devices 5a, 5b, 5c of the first screed segment 5 are activated at the start of the installation run. This may for example occur, if the positioning 7c is present according to FIG. 2. After expiration of a time period T1, the compacting devices 6a, 6b, 6c of the second screed segment 6 are activated. In this case, the time period T1 is selected such that the compacting devices 6a, 6b, 6c of the second screed segment 6 are activated when the installation start 7 is passed, for example, if the positioning 7d according to FIG. 2 is present.

[0041] In this way, suitable time periods T may be provided between the times of activation of any number of different compacting units 5a, 5b, 5c, 6a, 6b, 6c arranged one behind the other in the direction of travel F. Thereby, it can be ensured that the individual compacting devices 5a, 5b, 5c, 6a, 6b, 6c each are activated when the installation start 7 is passed. An analogous procedure can be provided for the deactivation at an installation end.

[0042] The time period T between the activation times of two compacting devices 5a, 5b, 5c, 6a, 6b, 6c may thereby be calculated based on a driving speed of the road finisher 1 in the direction of travel F and/or on a distance D (see FIG. 4) between the respective compacting devices 5a, 5b, 5c, 6a, 6b, 6c. In embodiments, in which the compacting devices 5a, 5b, 5c, 6a, 6b, 6c are activated according to grouped screed segments 5, 6, the distance D may also be defined between the screed segments 5, 6.

[0043] In FIGS. 3A and 3B, the connection between different components of the road finisher 1 and, in particular, of the screed assembly 2 is schematically shown. The control unit 10 can be seen. The control unit 10 may be provided on the road finisher 1 or on the screed assembly 2. It is connected to input devices 12 via first control lines 11. The input devices 12 may, for example, be a sensor unit 12a or an operating device 12b.

[0044] The sensor unit 12a may, for example, be configured to detect the driving speed of the road finisher 1 or to determine the same by means of other parameters, which can be detected by it. It is also conceivable that the control unit 12a is configured to detect the installation start 7 and/or the installation end, for example, by detecting the edge 8. This may, for example, occur by height sensors, which are already provided on the road finisher, such as used, for example for levelling. The sensor unit 12a can furthermore be configured to detect if and/or when the tractor 3 or the road finisher 1 start to move. A plurality of sensor units, which are configured for different purposes, is also conceivable.

[0045] The sensor unit 12a or the sensor units 12a may also comprise for example one or more temperature sensors, pyrometers, infrared sensors, ultrasonic sensors and/or path sensors. The installation start 7 or the installation end may then be detected, for example by means of an infrared sensor or a pyrometer on the basis of a temperature difference between the already laid layer and the layer still to be laid. The sensor unit 12a can comprise one or more sensors 16.

[0046] For example, sensors 16a, 16b, and 16c can be provided and configured to detect the installation start 7 or the installation end. Each of the sensors 16a, 16, and 16c may be allocated to the position of one or more of the compacting devices 5a, 5b, 5c, 6a, 6b, 6c. If one of the sensors 16a, 16b, 16c detects the installation start 7, the compacting device/s 5a, 5b, 5c, 6a, 6b, 6c allocated to it can be activated. When the installation end is detected, the compacting device/s 5a, 5b, 5c, 6a, 6b, 6c allocated to it can correspondingly be deactivated.

[0047] The operating device 12b may be configured to accept user data from the operator of the road finisher 1 or of the screed assembly 2. Similar to the control unit 10, it may be provided on both, the tractor 3 and the screed assembly 2. It is also conceivable that the operating device 12b and the control unit 10 are arranged in one and the same housing. However, an arrangement in different housings is also conceivable.

[0048] The control unit 10 may be a control unit 10, which is provided specifically for the control of the compacting devices 5a, 5b, 5c, 6a, 6b, 6c. However, it is also possible that the control unit 10 is also provided for the control of further functions of the road finisher 1.

[0049] The first screed segment 5 and the second screed segment 6 are indicated by broken lines. The screed segment 5 comprises a tamper drive unit 13a, a vibration drive unit 13b, and a pressure bar drive unit 13c. The tamper drive unit 13a may, for example, comprise an eccentric shaft, which, for example, may be actuated by means of a hydraulic motor or an electric motor. The vibration drive unit 13b may, for example, comprise an unbalance shaft, which, for example, may be actuated by means of a hydraulic motor or an electric motor. The pressure bar drive unit 13c may, for example, comprise a pulsed-flow hydraulic drive. A drive by means of electric actuators is also conceivable. The control unit 10 is connected to the drive units 13 of the first screed segment 5 via second control lines 14. The second screed segment 6 in the present embodiment, analogously to the first screed segment, comprises a tamper drive unit 15a, a vibration drive unit 15b, as well as a pressure bar drive unit 15c. These may be configured analogously to the drive units 13 of the first screed segment 5 and can be connected to the control unit 10.

[0050] In the present embodiment, two screed segments 5, 6 are provided, which each comprise three different compacting devices 5a, 5b, 5c, 6a, 6b, 6c and the associated drive units 13, 15. However, screed assemblies 2 are conceivable with any number of screed segments, for example only one screed segment or more than two screed segments. An individual screed segment or several screed segments each may also comprise arbitrarily different combinations of compacting devices 5a, 5b, 5c, 6a, 6b, 6c.

[0051] The control unit 10 may be an electrical control unit, a hydraulic control unit or an electro-hydraulic control unit. Accordingly, the control lines 11, 14 may be configured, i.e., they may be electrical as well as hydraulic control lines. In particular, the control lines 11 may be electrical lines. The control lines 14 may be configured depending on the type of the drive unit connected thereto. A control line 14, which is connected to a hydraulic drive unit 13, 15, may also be a hydraulic control line 14.

[0052] The control lines 14, as shown in FIG. 3A, may be branched control lines. These may be connected at a central connecting point, for example an output of the control unit 10, and then branch out correspondingly to the drive units 13, 15. According to FIG. 3B, however, for each drive unit 13, 15, a separate control line 14 may be provided. Furthermore, it is conceivable that for a first group of drive units, a branched control line 14 is provided, which connects a plurality of drive units from precisely this group to a connection of the control unit 10, and a second group of drive units, each connected to the control unit 10 by a separate control line 14.

[0053] Furthermore, as one skilled in the art would understand, the control unit 10 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 control unit may perform particular algorithms represented by the functions and/or operations described herein. The control unit 10 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.

[0054] The time periods T, T1 may be determined based on a distance D between the respective compacting devices 5a, 5b, 5c, 6a, 6b, 6c or screed segments 5, 6. The distance D may be defined in the direction of travel F. It can be defined in pairs between individual compacting devices 5a, 5b, 5c, 6a, 6b, 6c or screed segments 5, 6, or with respect to the compacting device 5a located furthest in the front or with respect to the screed segment 5 located furthest in the front, respectively. Moreover, it may be defined between the front ends of the corresponding compacting devices 5a, 5b, 5c, 6a, 6b, 6c, screed segments 5, 6, respectively, as shown in FIG. 4 right-hand side, or between the back end of the compacting devices 5a, 5b, 5c, 6a, 6b, 6c or screed segments 5, 6, as shown in FIG. 4 left-hand side. The same applies to distances D between screed segments 5, 6.

[0055] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms according to 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 according to the disclosure.