DE29908429U1 - Device for adjusting the working distance - Google Patents

Description

Applicant: MULAG Fahrzeugwerk Heinz Wössner GmbH u. Co. KG

Our file: 49778 Al/Me/Gr

DEVICE FOR ADJUSTING THE WORKING DISTANCE

I. Area of application

The invention relates to boom work devices which carry a working head, such as a mowing head, brush head, suction head or the like, at the free end of a boom arm which usually consists of several arm elements.

Such boom implements are often in the form of a vehicle on whose front or rear mounting surface the boom arm is mounted and whose functions are supplied with energy by the vehicle's hydraulics and controlled by a control system housed in the vehicle.

Such boom implements are often used to maintain the verge areas next to roads, to wash tunnel walls, etc., whereby the vehicle drives on the road and, using the boom arm and the work head attached to it, mows the grass, clears bushes, collects rubbish or performs similar work on the strip next to the road.

It is known that the boom arm - which extends transversely to the direction of travel in the working position - consists of two arm elements, the upper arm and the lower arm. The upper arm is pivotable about a longitudinal axis relative to the mounting surface of the vehicle and its angular position can be adjusted via a first hydraulic cylinder, the upper arm cylinder. The lower arm is attached to the free end of the upper arm in an articulated manner.

The angle between the two can be controlled via a hydraulic cylinder, the forearm cylinder.

The working head is pivotably mounted on the free end of the lower arm so that the angle of the working head can be adjusted to the inclination of the ground. This setting can be made using a hydraulic cylinder between the lower arm and the working head, the head cylinder, or by other means such as spring-loaded rollers on the working head relative to the ground, etc.

The pivot axes of the individual parts generally run parallel to one another, and the entire boom arm can often be pivoted about a vertical axis relative to the mounting surface of the vehicle in order to be able to be moved from the laterally projecting working position to a deactivated position in which the entire boom arm including the working head does not protrude or only protrudes slightly above the base area of the vehicle.

An important function of such boom work equipment is the exact adjustability and maintenance of a desired distance between the working head and the work group, usually the ground, whereby this distance is preferably measured perpendicular to the work surface or the ground.

In order to increase the working distance of the working head, for example, it is known to extend the upper arm cylinder and/or the lower arm cylinder a little further, which gives the working head more distance from the ground. The fact that the lateral distance of the working head to the vehicle measured along the ground is changed slightly is irrelevant, as this is less than the overlap of the individual tracks of the working head required for clean surface processing, as long as the ground to be processed by the working head is approximately horizontal or approximately parallel to the lane on which the vehicle is moving.

However, the terrain next to a road is often steeply inclined relative to the road, forming a relatively steeply rising counter slope from the road level or an embankment that drops steeply from the road level.

If the operation of the upper arm cylinder and/or lower arm cylinder is used to change the working distance, i.e. the working height, above the ground, measured perpendicular to the ground, this causes a significant shift in the track that the working head follows and can also lead to the left or right end of the working head cutting into the

&iacgr;&ogr; underground.

It is therefore the object of the invention to create a method and a device with the aid of which the working distance of the working head from the ground, measured in particular perpendicular to the ground, can be changed and adjusted in the case of a boom work device, even on steeply inclined ground.

This object is achieved by the features of claims 1 to 4. Advantageous embodiments emerge from the subclaims.

In order to keep the track shift as small as possible or to prevent any track shift of the working head at all, relative movements are made on the boom work device in directions that have the smallest possible directional deviation from the perpendicular to the ground, or such movements are combined in such a way that no track deviation of the working head occurs. The movements are preferably carried out automatically, in particular by means of an electronic control system, which also carries out the selection of the respective direction of movement as well as the selection and extent of the relative movement required for track compensation.

A first possibility for relative movement is to change the length of an arm element of the boom arm, i.e. in the case of a two-part boom arm

(upper arm-forearm) ζ. B. a change in the length of the forearm, for example through telescoping of the forearm.

In the case of a three-part boom arm, this can be a change in the intermediate angle between the outermost and the penultimate arm element, which together then correspond to the lower arm.

The more precisely the direction of the forearm corresponds to the vertical to the ground, the smaller the lateral offset, i.e. the track shift, of the working head is when the working height of the working head is changed by changing the length of the forearm.

Preferably, with this type of working height adjustment, the boom arm should be adjusted so that the arm to be adjusted in length, for example the forearm, corresponds as closely as possible to the perpendicular to the ground. This is particularly important if there is also the option of changing the length of the upper arm, for example by telescoping it. Then the angle of the forearm to the ground can be adjusted by changing the length of the upper arm.

A second option is to move the entire boom arm across the direction of travel relative to the working device, e.g. the vehicle, which is usually done in a horizontal direction. Due to the angle between this horizontal transverse direction and the perpendicular to the surface to be worked on, this usually results in a track offset of the working head.

A third possibility is to change the angle between the elements of the boom arm, e.g. between the upper arm and the lower arm, by extending or retracting the corresponding hydraulic cylinder.

For vehicles where the transverse shift (second option) is not available, you only have the choice between the first and third options.

When choosing from the three options, it is therefore important to consider which of the two variants results in the smallest track offset of the working head, in particular how the angle differences compared to the perpendicular to the ground are compensated for, on the one hand by the arm element that can be adjusted in length, on the other hand by the transverse displacement of the entire boom arm or the change

�iacgr;γ its bending angle.

The selection of which of the two or three available options for working height adjustment is used can be made manually, but this selection should preferably be made automatically by the control system.

The option used is primarily the one whose resulting direction of displacement of the working head has the smallest angular deviation from the perpendicular to the surface to be worked on, for example the subsoil. For this purpose, the current inclination of the surface to be worked on or the subsoil must be permanently known, which is preferably done by arranging an inclinometer directly on the working head, which constantly reports the current inclination angle of the working head, which is always kept parallel to the subsoil by a scanning roller and corresponding sensors, to the control system for the boom arm via a signal line.

A secondary decision criterion is the reaching of a maximum position with the type of movement selected according to the primary decision criterion, so that a further displacement with the primarily selected type of movement is no longer possible. Then the second best option available, i.e. the second smallest deviation of the resulting direction of movement of the working head from the perpendicular to the processing surface, must be used.

Furthermore, the absolute angular position or the relative angular position to the work surface or to the parallel working head must be known, which can be measured by appropriate sensors on the arm parts of the boom arm and forwarded to the control system:

These can be sensors for measuring the relative angular position to the neighbouring component, for example in the case of the lower arm in relation to the working head or in the case of the upper arm in relation to the vehicle, or absolute &iacgr;&ogr; angle sensors on those components whose absolute angular position must be known:

When telescoping an arm part, this is the corresponding arm part; when changing the angle between two articulated arm parts, this is both arm parts, since the direction of movement can be determined from this; and when moving transversely, this is the angular position of the surface or guide along which the transverse movement takes place.

In addition, the absolute angular position of the working head or the work surface is required, which is determined on the working head using an inclination sensor.

Another possibility is to combine the available procedures and - by breaking down the direction of travel (perpendicular to the ground) - break them down into components of the available directions of movement (e.g. direction of the telescopic arm element and transverse displacement direction of the boom) and using these two options to complement each other, lift the working head in a direction perpendicular to the ground and thus avoid the working head deviating from its track.

For the transverse displacement, the entire base plate on which the boom arm is mounted is preferably moved horizontally along guides across the working surface of the vehicle. The resulting one-sided weight load on the vehicle is preferably balanced out by moving a counterweight, which is also mounted on the working surface, in the opposite direction.

All this can be controlled manually from the driver's cab of the vehicle, but preferably it is done automatically using the electronic control system that controls the entire boom work device.

Similar problems occur not only when working on an opposing slope, but also on a sloping embankment directly next to the road. Here too, one of the two measures described above or both measures in combination can achieve very precise tracking of the working head parallel to the direction of travel of the vehicle despite changes in the working distance, i.e. the working height.

Tracking is therefore of great importance as it significantly influences the efficiency of surface processing.

As soon as the track driven by the working head is not straight and parallel to the direction of travel, but curves, lens-shaped, unprocessed residual areas remain between the track just processed and the track previously driven. These residual areas must be reworked later in separate work steps, or the lateral overlap of the individual tracks must be chosen to be large enough that these residual areas no longer occur, which, however, drastically reduces the effective working width of each track.

An embodiment according to the invention is described in more detail using the figures as an example. They show:

Fig. 1: the boom work tool in working position viewed in the direction of travel and with level ground at the processing point,

Fig. 2 the boom working device when working on a counter slope,

Fig. 3 the track course with incomplete angle compensation compared to the vertical to the ground, and

&iacgr;&ogr; Fig. 4 the working device when working on a slope.

Figures 1, 2 and 4 show a vehicle 4 as a working device, viewed in the direction of travel 10, i.e. for example from behind, with the boom arm 14 being mounted on the mounting surface 4a located behind the driver's cab, usually the loading area of a commercial vehicle.

This consists of an upper arm 11, which can be pivoted about a horizontal pivot axis 18a relative to the vehicle 4, wherein the angular position can be adjusted by a hydraulic cylinder arranged between them, the upper arm cylinder 1.

The upper arm 11 is either attached directly to the mounting surface 4a, or on a base plate 8, which can be moved along guides as shown in Fig. 2, transversely to the direction of travel 10 on the mounting surface 4a of the vehicle 4.

To compensate for the weight, the same can be done with a counterweight 7, which is also arranged on the mounting surface 4a.

At the free end of the upper arm 11, the lower arm 12 is arranged so as to be pivotable about a further pivot axis 18b, the angular position being held by the lower arm cylinder 2.

•&igr;

At the free end of the lower arm 12, the working head 13 is arranged so that it can pivot about a further pivot axis 18c in order to be able to guide it parallel to the ground G. This adjustment can be carried out using the additional hydraulic cylinder shown, the head cylinder 3, or also by other means.

As shown in Fig. 1, when the ground is essentially horizontal or parallel to the vehicle's track, the working distance D can be adjusted by extending the upper arm cylinder 1 without a significant shift in the track of the working head 13 occurring, in particular the smaller the height difference between the ground beneath the working head 13 and the pivot axis 18a of the upper arm 11.

In the illustration in Fig. 2, which shows working on a counter slope, it becomes clear that extending the upper arm cylinder 1 not only causes the desired increase in the working distance d by 6d, but also an undesirable strong track offset, so that - as shown in Fig. 3 - the track 15 of the working head 13 is displaced upwards on the counter slope and can only be returned to the old track when the working distance is subsequently reduced to the original height d, so that an unprocessed lens-shaped residual surface 16 would remain compared to the previously processed track 15'.

The closer the opposing slope begins to rise next to the lane of the vehicle 4, the greater the risk that this procedure will even cause a corner of the working head 13 to cut into the ground.

Operating the lower arm cylinder 2 instead of the upper arm cylinder 1 is also not very helpful, since this usually results in an even greater track shift when adjusting the distance d.

• * • ·

Fig. 2 shows a boom work device in which - in contrast to that in Fig. 1 - the lower arm 12 is telescopic in length. When the working distance d is changed by changing the length of the lower arm 12, only a small track offset 6s results - since the perpendicular 20 to the ground only has a relatively small angle difference to the lower arm 12 - which is brought about by changing the working distance by 6d by changing the length of the lower arm by 6du.

&iacgr;&ogr; If, however, the change in distance 5d is brought about exclusively by transverse displacement of the entire boom arm 14 along the mounting surface 4a, it can be seen from the vector diagram that this already results in a larger track offset 6s, due to the larger angular difference of this transverse displacement direction with respect to the vertical 20 than that of the direction of the lower arm 12.

However, the vector diagram shown in Fig. 2 close to the working head 13 also shows that by combining both movements, i.e. 5du and ödq, a track offset 5s = 0 can be achieved if the extent of the two mutually compensating movements is specified in the correct ratio by the electronic control.

For reasons of simplifying control, it can also be specified to first use the change in length of the lower arm, placing it as perpendicular to the ground as possible, and only if a limit value of 5s _max as the maximum acceptable track deviation is exceeded to carry out compensation by simultaneously moving the boom arm laterally on the vehicle.

In order to avoid lateral pitching movements of the vehicle, which also affect the working distance d, the additional

and opposite displacement of a counterweight 7 to the boom arm during its transverse displacement on the mounting surface 4a.

When working on an embankment that slopes down next to the roadway, as shown in Fig. 4, it is clear that the telescopic ability of the lower arm 12 is not only necessary for sensitive control of the working distance d, but also in order to be able to reach very low embankment areas close to the vehicle.

&iacgr;&ogr; The sensitivity of the adjustability of the working height d also speaks in favor of the use of the transverse displacement in particular, but also the telescopic ability of the lower arm, since by operating the lower arm cylinder 1 - with the conventional procedure for changing the working height - the entire boom arm naturally begins to vibrate slightly, which causes an uneven distance between the working head and the ground a few seconds after the adjustment.

In contrast, linear telescoping of the lower arm does not cause such vibrations in the areas of the boom arm that are closer to the vehicle, and the transverse displacement of the entire boom arm has only a minor effect on the working height due to the intermediate angle to the vertical of the ground.

Thus, the distance of a working head 13 from the ground G, in particular an opposing slope, is adjusted, with the working head 13 at the free end of a boom arm 14 transverse to the direction of travel 10 of a working device, with the adjustment being carried out by changing the length of one of the arm elements of the boom arm.

The adjustment can also be carried out by changing the length at the end, especially in the case of an upper arm 11

and forearm 12 existing boom arm 14 at the forearm 12 of the boom arm 14.

The adjustment can also be carried out by changing the length by telescoping the arm element, in particular the forearm 12.

The adjustment can also be carried out by setting the arm element or forearm 12 as perpendicular as possible to the base G before or at the latest when the length is changed.

The adjustment can also be carried out by transverse displacement of the entire boom arm 14.

The adjustment can also be carried out by the transverse displacement of the boom arm 14 relative to the work device, in particular to the vehicle 4 on which the boom arm 14 is mounted.

The adjustment can also be carried out by moving a counterweight 7 relative to the working device or vehicle 4 in the opposite direction to the transverse displacement of the boom arm 14.

The adjustment can also be carried out by the transverse displacement of the boom arm 14 occurring in or against the cantilever direction viewed in the top view.

The adjustment can also be carried out by transverse displacement of the entire boom arm 14, whereby the selection between length change of the arm element and transverse displacement of the boom arm 14 is made automatically.

The adjustment can also be carried out by making the selection in such a way that first the change in length of the arm element or lower arm 12 is fully utilized, only then is the transverse displacement of the boom arm 14 used and when both possibilities have been exhausted, if necessary the increase in the intermediate angle between the arm elements, in particular between the upper arm 11 and lower arm 12, is used in the sense of increasing the boom width.

The adjustment can also be carried out by selecting where the effective angle is smaller, namely either when changing the length of the arm element or forearm 12, the angle between the length-adjustable arm element and the vertical 20 with respect to the base G or the intermediate angle between the direction of displacement of the transverse displacement and the vertical 20 with respect to the base G.

The adjustment can also be carried out by changing the length of one of the arm elements of the boom arm and/or by adjusting the length by moving the entire boom arm 14 transversely, whereby the choice between changing the length of the arm element and moving the boom arm 14 transversely is made such that the working head 13 in the vertical position on the ground G always moves in the same track parallel to the direction of travel 10 of the working device or vehicle 4.

LIST OF REFERENCE SYMBOLS

1 upper arm cylinder

2 Forearm cylinder 2a Outer tube

2b Inner tube

&iacgr;&ogr; 3 head cylinder

4 Vehicle

4a Mounting surface

5 Shifting device

6 Control

7 Counterweight

8 Base plate

10 Direction of travel

11 Upper arm

12 Forearm 13 Working head

14 boom arm

15 track

16 Remaining area

17 Wheel

18a, b, c, d swivel axis

20 perpendiculars

d distance

G Subsurface

Claims (4)

PROTECTION CLAIMS 1. Boom work device with a boom arm consisting of several articulated arm elements, in particular upper arm (11) and lower arm (12), and a working head (13) arranged at the free end of the boom arm (14), &iacgr;&ogr; characterized in that the lower arm (12) of the boom arm (14) is variable in length, in particular telescoping, and controls the length of the lower arm (12) with regard to the desired distance (d) between the working head (13) and the working surface, in particular the ground (G) via a control (6) of the working device. 2. Boom working device with a boom arm consisting of several articulated arm elements, in particular upper arm (11) and lower arm (12), and a working head (13) arranged at the free end of the boom arm (14), characterized in that the boom arm (14) can be displaced relative to the working device or vehicle (4) transversely to the direction of travel (10), in particular horizontally transversely, and the transverse displacement is controlled by means of a control (6) of the working device in accordance with the distance (d) of the working head (13) from the working surface, in particular the ground (G). 3. Boom work device with a boom arm consisting of several articulated arm elements, in particular upper arm (11) and lower arm (12), and a working head (13) arranged at the free end of the boom arm (14), characterized in that • · »&Lgr; Cf * · · The lower arm (12) and upper arm (11) are connected to one another in an articulated manner and the intermediate angle is controlled by means of a control of the working device in accordance with the distance (d) of the working head (13) from the working surface, in particular the ground (G). 4. Boom working device with a boom arm consisting of several articulated arm elements, in particular upper arm (11) and lower arm (12), and a working head (13) arranged at the free end of the boom arm (14),
&iacgr;&ogr; characterized in that the lower arm (12) of the extension arm (14) is adjustable in length, in particular telescopic, the boom arm (14) can be displaced relative to the working device or vehicle (4) transversely to the direction of travel (10), in particular horizontally transversely,
- the intermediate angle between two articulated arm elements is adjustable, and/or the relative angle between the first arm part of the boom arm attached to the vehicle and the vehicle is adjustable, and
that a control is available which can control all of the aforementioned adjustment options and which enables the selection of the adjustment method of the distance of the working head from the work surface from at least two of the following adjustment methods: Adjustment by transverse displacement of the entire boom arm (14), - Adjustment by changing the length of one of the arm elements of the boom arm (14), and/or Adjustment by changing the angle between two articulated arm parts, is carried out automatically depending on which adjustment method results in a resulting adjustment direction of the working head that is closest to the vertical in relation to the working surface, in particular the substrate (G), and in particular the compensation of the resulting The track offset is adjusted simultaneously or immediately afterwards by the other adjustment method whose resulting adjustment direction of the working head is closest to the inclination of the work surface.