EP0817889B1 - Double-belt soil-compacting device and steering system therefor - Google Patents

Abstract

The invention concerns a double-belt soil-compacting device (5) having a pivoting steering system for the two belts (13a, 13b) and a control unit which is connected to a first and a second belt-pivoting unit and by means of which a first pivoting angle of the first belt (13a) can be automatically adjusted by means of a control unit in non-linear dependence relative to the second pivoting angle of the second, other belt (13b) during a pivoting process. Consequently, the transition from track-following to crab-like travel behaviour and vice versa with the two belts (13a, 13b) mutually offset laterally (d) can be carried out automatically, in particular without meandering. Owing to the easy transition from track-following to crab-like travel behaviour, the device can travel along, and very close to, a boundary without the risk of damaging said boundary during the transition.

Description

The invention relates to a method according to the preamble of claim 1 and a device according to the Preamble of claim 5.

Soil compaction devices, especially road rollers, are used for compaction of soil layers e.g. B. used during road construction. There are z. B. in the substructure unbound layers such as gravel layers, ... or in the superstructure bound layers such as asphalt, ... compacted. For compaction, the soil compaction device is moved back and forth on the layers to be compacted. There are soil compaction devices which can be steered by means of an articulated steering system shown in FIG. 1a or a schematic steering system shown in FIG. 1b . The representations in FIGS. 1a and 1b are greatly simplified and show only the elements necessary for the steering process schematically.

A soil compacting device 1 with articulated steering ( FIG. 1a ) has only a single pivot point 2, with which the two bandages 3a and 3b can be pivoted against one another for cornering. The articulated soil compacting device 5 ( FIG. 1b ) has two pivot points 7 and 9 on the machine frame 11 for the two bandages 13a and 13b which are spaced apart from one another in the machine longitudinal axis direction by a distance a . In the following, only the soil compaction device 5 with a steer steering will be discussed.

For cornering, as shown in FIGS. 1b and 2 , the front and rear drums 13a and 13b are pivoted synchronously with respect to one another by the curve angle τ during the steer steering. For good soil compaction, it is now often necessary to compact the soil directly up to a side obstacle or a boundary 15 (wall, curb, ...).

Road rollers with the above-mentioned steering are from DE-PS 884 207, US-A 3 947 142, the US-A 3 868 194 and DE-A 23 45 412 known. This Road rollers are now with bandages running true to the track (Rollers) as well as with bandages offset to one side (so-called dog walking) movable. For guiding the roller vehicle the front one was on a predetermined path to be condensed and also the rear bandage by hand only preferred via a linear steering power amplifier by roller guides according to the desired direction of travel deflected.

If it is now to be moved laterally away from a boundary 15 , this is not readily possible since, as shown in FIG. 2 , the bandage 13b which is at the rear in the direction of travel 23 would move into the boundary 15 . The roller operator circumvents this difficulty by not moving as close to the boundary 15 as desired.

The object of the invention is to allow the roller operator Soil layers close to a boundary compress and then easily move away from it laterally, even if he was in, for whatever reason straight ahead driving along an obstacle is.

The task is solved in that the transition from true-to-track procedure for "dog walking" with laterally offset Contrary to the state of the art, bandages are no longer manual is set, but both bandages automatically can be adjusted by an adjustment mechanism. At the booth The technology had been completely overlooked that a roller operator not at all when moving a roller vehicle Was able to double the driving behavior at the same time Control of the two drums to accomplish. The deflection link of the two bandages would have in one must be done in a non-linear manner. Nonlinear links are not at all or difficult for humans perform. To make matters worse, there was always one Bandage during the process was in the back of the roller driver. In order to avoid being overwhelmed, the Roller guides instinctive safety margins introduced. To Obstacles that could be damaged by the rollers, a large "safety distance" was therefore chosen.

In the steering method according to the invention, the Concentrate the roller driver completely in the direction of travel. Of the Transition from track-true driving to crab walking and again back is carried out automatically by a control unit. The other, second bandage is adjusted no longer, as with one of the well-known four-wheel steering systems in linear dependency, but non-linearly accordingly the ratios set out below. Four wheel steering are for example in DE-A 43 32 287, the DE-A 40 06 149 and DE-A 44 19 131 described solve but not the problem of a transition from a track-true Driving (= two-wheel and four-wheel steering) in a crab-like Driving behavior with a lateral offset of the two bandages to each other. By pivoting the invention the second, different bandage in a nonlinear Depending on the first bandage, it is possible for the first time without any risk of limit damage a bandage when driving straight ahead to limit the side to move and still fully in the direction of travel on any obstacles that may appear there and on the to concentrate the actual compression process.

That is, along a straight method, for example a limit also moves during the transition to the "Hundegang" the leading bandage straight, parallel and close to the boundary. Even with one Cornering is the transition to crab walking and back again in the true-to-track procedure according to the below Executions with compliance with an already chosen Direction of travel possible. Also during the transition in the direction of the dog can be changed. A There would be a serpentine line with all the consequences of touching an obstacle if a roller operator, according to the prior art, driving near a boundary separated by manual operation Steering units the front and the rear drum would try to swivel, so as to drive crab-like to get away from the obstacle.

The expression "without a recognizable serpentine line" is used knowing that every control system is based on its controlled variable must create a serpentine line. This is typical of the regulation Snake line is not considered because whose amplitude is usually not recognizable and also in bears no relation to the deflections as they go through the separate manual steering of the two bandages takes place would.

The term "dog walk" was used for clarity chosen. A dog can have its rear end when running move laterally against his front legs and still straight ahead as well as a curve desired by him.

Fig. 1a

eine schematische Darstellung der Bandagenverstellung einer Verdichtungsvorrichtung mit Knicklenkung und

Fig. 1b

mit Schemellenkung,

Fig. 2

eine Verdichtungsvorrichtung mit Schemellenkung an einer Begrenzung der zu verdichtenden Schichten in Kurvenfahrt,

Fig. 3

eine schematisch dargestellte Verdichtungsvorrichtung im Hundegang in Geradeausfahrt,

Fig. 4

in Kurvenfahrt sowie in den

Fig. 5a und 5b

bei einem Übergang von der spurgetreuen Verfahrweise in den Hundegang und in

Fig. 6

hierzu eine trigonometrische Darstellung mit Funktionselementen der Vorrichtung,

Fig. 7

ein Einstelltableau zur Einstellung einiger Funktionen der Verdichtungsvorrichtung, insbesondere des Hundegangs sowie

Fig. 8

ein Flußdiagramm, welches den selbsttätigen Übergang in den Hundegang bei Geradeausfahrt für ein Versetzen der nachlaufenden Bandage gemäß Figur 6 zeigt, wobei ▴δ das Winkelinkrement für die Verstellung der nachlaufenden Bandage 13b, ▴t das Zeitinkrement für die schrittweise Berechnung der Verstellung, v die Fahrzeuggeschwindigkeit und ▴d die resultierende zusätzliche Auslenkung der nachlaufenden Bandage 13b nach dem Zeitinkrement ▴t ist.

In the following, examples of the method according to the invention and the device according to the invention are explained in more detail with reference to drawings. Further advantages of the invention result from the following description. Show it:

Fig. 1a

is a schematic representation of the bandage adjustment of a compaction device with articulated steering and

Fig. 1b

with stool steering,

Fig. 2

a compacting device with schematic steering at a boundary of the layers to be compacted when cornering,

Fig. 3

a schematically illustrated compression device in a dog walking in a straight line,

Fig. 4

in cornering as well as in the

5a and 5b

at a transition from the track-true procedure to the crab and in

Fig. 6

a trigonometric representation with functional elements of the device,

Fig. 7

a setting panel for setting some functions of the compaction device, in particular the dog walking as well

Fig. 8

a flowchart showing the automatic transition to dog walking when driving straight ahead for moving the trailing bandage according to Figure 6 , where ▴δ the angular increment for the adjustment of the trailing bandage 13b , ▴t the time increment for the gradual calculation of the adjustment, v the vehicle speed and ▴d is the resulting additional deflection of the trailing bandage 13b after the time increment ▴t.

To explain the steering conditions in a crab-like method of a soil compaction device, here a roller vehicle 5 , is followed by a lane-true driving, such as. B. shown in Figures 2 and 5a .

When driving straight ahead, the steering angles α and β between a vertical 21a or 21b on the respective drum axis 19a or 19b and a vertical 22a or 22b on the machine axis 17 for the front and rear drum 13a and 13b are equal to 90 °. When cornering shown in Figure 2 is then α = 90 ° + τ and β = 90 ° - τ, where τ is called the curve angle.

If the two bandages 13a and 13b are laterally offset from one another when driving straight ahead, ie brought into dog walking, as shown in FIG. 3 , the steering angles α and β result in τ = 0 α = β = 90 ° + δ, where δ is the "crab angle".

A cornering in crab, as shown in Figure 4 , is then a superimposition of the above steering processes. The steering angles are then α and β α = 90 ° + τ + δ and β = 90 ° - τ + δ

In order to move laterally away from the boundary 15 without going into it, the roller vehicle 5 , as shown schematically in FIGS. 5a and 5b , must be brought into the crab from the track-true method of travel, in which the rear bandage 13b in the direction of travel 23 is opposite the front 13a is distanced from the boundary 15 by a distance d. FIG. 5a shows the starting position with the two bandages 13a and 13b adjacent to the boundary 15 . FIG. 5b shows the final state in which the roller vehicle 5 can be moved in dog walking along the boundary 15 with a distance d between the rear bandage 13b .

In order to get into this crab, the bandages 13a and 13b are to be adjusted, the pivoting angles δ _h and δ differing from the state in FIGS. 3 and 5b during the adjustment process, the front 13a in the direction of travel 23 and the rear bandage 13b relative to the machine axis 17 _V.

The adjustment of the pivoting angles δ _h and δ _{V will} be explained with reference to FIG. 6 . Figure 6 shows schematically with solid lines the position of the two drum axes 19a and 19b according to Figure 5a ("true to the track" initial state). The distance between the two drum axes 19a and 19b is a; more precisely, the distance between the two pivot points 7 and 9 . If the rear drum axis 19b has now been adjusted by the swivel angle δ _h and the distance b has been traveled with this drum 13b , the front drum axis 19b must then be swiveled by the swivel angle δ _V , otherwise the front drum 13a would no longer be at the boundary 15 drive along, but into it. According to the laws of the oblique-angled triangle [see e.g. B. Hütte des Ingenieurs Taschenbuch, 28th edition, Theoretical Foundations, Berlin 1955, page 73] follows sin δ V = (b / a) · sin δ H (Sin rate).

According to this relationship, the drum axis 19a of the front drum 13a can now be pivoted in accordance with the pivoting of the rear drum axis 19b . The incrementally small changes in the pivoting angle are now chosen to be so large as a function of the distance b of the rear drum 13b that has now been covered in each case that no cracking can occur due to the shear forces acting on the soil to be compacted.

When the desired lateral offset d has been reached for the dog walking, as shown in FIG. 5b , the two pivoting angles α and β are of the same size according to the above statements. δ = δ h 'end = arc [sin (d / b)]

Depending on the desired speed to achieve the lateral offset d and the shear strength of the soil to be compacted, pivoting angles δ _v and δ _{h of} the front and rear bandages 13a and 13b can be set, which are above the pivoting _end angle δ _{h 'end} (= crab angle δ). However, in the course of the adjustment process over time, it must be ensured that when the desired crab position (distance d ) is reached, the pivot angle δ _{V has to reach} the angle δ _{h 'end} without exceeding the maximum shear stress on the floor.

The crab is always set in such a way that the rear 13b bandage in the direction of travel 23 is spaced from the boundary 15 .

Due to the regulation size of the swivel system there is always a so-called control deviation. This rule deviation should advantageously be determined experimentally and then according to the pivoting of the front bandage be overlaid. A remaining mistake can be made by the roller operator be compensated for by slight cornering.

The steering process for adjusting the two bandages 13a and 13b is carried out according to the instructions by the roller guide via the control unit 31 , which has measuring points 29a and 29b for the distance traveled or the travel speed and measuring points 27b and 27b for the actual adjustment angle of the bandage 13a concerned and 13b and actuators of the pivoting device 25a and 25b cooperate. The control unit 31 is a digital computer (processor). The condition to be observed for the steering is: The distance of the advancing bandage 13a , see FIGS. 5a and 5b , to a straight obstacle (limitation) 15 (effective or to an imaginary, in particular straight line) must remain constant during the transition to the dog walker, while the distance d of the trailing rear bandage 13b changes , as shown in the transition from FIG. 5a to FIG. 5b . This condition is met if, during the transition to the crab, the angle between the boundary 15 in FIG. 6 and the axis 19a of the advancing bandage (direction of travel 23 ) in the example shown there at all times and regardless of the position or the distance covered trailing bandage 19b is always 90 ° (with a straight line). The correction angle by which the leading bandage 19a has to be adjusted continuously or incrementally is the above-mentioned angle δ _v , which can be determined from the trigonometric relationship for each position of the following bandage 13b . This determination is carried out by the control unit 31 and gives the necessary commands to the pivoting devices 25a and 25b . Shortly before the predetermined distance d from the boundary 15 is reached , the control unit 31 ensures a smooth transition into the parallel position of the rear drum 13b ; δ _v = δ _h . As a result, the predetermined distance d is then reached after completion of the steering maneuver, the trailing drum 13b then rolling parallel to the boundary 15 . A reset to a true-to-the-track journey is carried out analogously. When the transition to the parallel position takes place depends, among other things, on the type of material to be compacted and what shear forces are permitted as a result of the steering process. This change in angle as a function of the travel speed is material-specific and can be entered into the control unit 31 as a "control constant". This entry is not shown. For this purpose, preference will be given to a setting switch with a plurality of positions which, according to different material properties, specify different angular rate of change.

The transition from true-to-track driving to crab walking and back again is made by pressing the corresponding button 37g, 37h or 37i mentioned below .

To carry out the dog walking described above, each bandage 13a and 13b has a pivoting device 25a and 25b for pivoting the bandage axes 19a and 19b and a measuring device 27a, 27b, 29a and 29b each for measuring the actual actual pivoting angle δ _h and δ _V and the path covered with the bandage in question b . The pivoting devices 25a and 25b and the measuring devices 27a, 27b, 29a and 29b are connected to a control unit 31 which, in accordance with the above statements, specifies the specifications for the desired pivoting angle in accordance with the measured values. As indicated schematically in FIG. 6 , this control unit 31 is acted upon by a steering unit 33 with which, according to FIG. 4 , cornering in dog walking, when changing to dog walking and in lane-true driving is also possible by "steering" by the roller operator.

In order to relieve the roller operator of unnecessary operating procedures and to direct his attention to the area to be compacted and its boundaries, an input panel 35 , shown in FIG. 7 , is connected to the control unit 31 . This input panel 35 has nine key fields 37a to 37i arranged in three rows. The top three key fields 37a to 37c are used to set the vibration state of the bandages 13a and 13b . The key fields 37d to 37f arranged in the middle row serve to set the water sprinkling of the bandages 13a and 13b . The lowest keypads 37g to 37i are used to adjust the dog walking . With the keypad 37g, a distance d is similar to Figure 6 of the rear drum 13b and to the left produced the keypad 37i to the right of a boundary 15th With the middle keypad 37h , the transition from dog walking to a true-to-lane driving style is made.

For the sake of simplicity, in a preferred embodiment variant, the distance d of the crab is already set at the machine type during assembly. It can also be generated with appropriate (not shown) input elements a dog walking desired distance.

The adjustment of the drum axles 19a and 19b by the relevant pivot angle δ _h or δ _v is preferably carried out via hydraulic (not shown) piston-cylinder units; but other adjustment units, such as. B. a superposition gear, an electric drive, ... can be used.

Claims (9)

1. Method of steering a ground-compacting device (5) with two rollers with swivel steering for the two rollers (13a, 13b), characterized in that a setting of a first swivel angle (δ_h, δ_v) for a first (13a) of the two rollers (13a, 13b) is started by the release of a signal and, at the same time, a second swivel angle (δ_v, δ_h) for the other, second roller (13b) is automatically set, in dependence on the instantaneous first swivel angle (δ_h, δ_v), by means of a control unit (31), in accordance with an adjustment allowance, in a non-linear manner such that a transition takes place from a track- following movement behaviour to a crabwise movement behaviour with a lateral offset (d) of the two rollers (13a, 13b) relative to one another, in order, preferably during compacting close to a boundary (15), to be able to drive the device (5) straight ahead without problems and without any danger of damaging the boundary, particularly with the forward roller (13a) close to the boundary (15) and with the following roller (13b) at a distance (d) therefrom, and in order, in particular, to drive without "snaking" during the transition to a predetermined direction of travel.
2. Method according to Claim 1, characterized in that the first, actual swivel angle (δ_h, δ_v) is measured automatically and the second target, swivel angle (δ_v, δ_h) is set automatically from the measured value and the adjustment allowance, with the aid of the adjustment allowance.
3. Method according to Claim 1 or Claim 2, characterized in that the distance (b) travelled by at least one of the rollers (13a, 13b) is measured and the target swivel angle (δ_v, δ_h) is determined and set in dependence on the measured distance (b) of the rollers (13a, 13b).
4. Method according to any one of Claims 1 to 3, characterized in that, during a change in direction of travel to be executed by the driver of the device, a cornering swivel angle (τ) is automatically superimposed on the first and second target swivel angles by the control unit (31).
5. Ground compacting device (5) for implementing the method according to any one of Claims 1 to 4, with swivel steering comprising a steering unit (33) for the two rollers (13a, 13b), characterized by a control unit (31) which is connected to a first and a second roller-swivelling unit (25a, 25b), and by which a first swivel angle (δ_v) of the first roller (13a), predetermined by the steering unit (33), can be set automatically in non-linear dependence on the second swivel angle (δ_h) of the second roller (13b) during a swivelling process, in a manner such that a transition between a track-following movement behaviour and a crabwise movement behaviour with a lateral offset (d) of the two rollers (13a, 13b) relative to one another can be executed automatically and, in particular, without "snaking".
6. Ground compacting device (5) according to Claim 5, characterized by a cornering unit (33) which is connected to the control unit (31), and by which a cornering angle (τ) can be superimposed on each of the first and second swivel angles (δ_v, δ_h) for cornering.
7. A ground compacting device (5) according to Claim 5 or Claim 6, characterized by at least a first measuring unit (27a, 27b) for the measurement of the swivel angle (δ_v, δ_h) of at least one roller, preferably the rear roller (13b), in the direction of travel (23) at the time in question.
8. Ground compacting device (5) according to any one of Claims 5 to 7, characterized by at least a first distance measuring unit (29a, 29b) for measuring the distance (b) covered by at least one roller, preferably the rear roller (13b) in the direction of travel (23) at the time in question.
9. Ground compacting device according to any one of Claims 5 to 8, characterized by a input unit (35) which is connected to the control unit (31) and comprises at least two input positions (37g, 37i) and by means of which it is possible to execute a lateral offset of one of the rollers (13a, 13b) relative to the other (13b, 13a), to the left or to the right in the direction of travel (23).

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