EP2947044B1 - Method for steering control in an industrial truck - Google Patents

Description

The invention relates to a method for steering control in an industrial truck. In particular, the invention relates to a method for steering control in an industrial truck in which all wheels of a front axle and a rear axle can be steered, and which has a trailer hitch and / or a hinged fork and / or extendable load arms.

Forklift trucks include counterbalance forklifts and reach trucks, as well as tractors. In a counterbalance forklift, it is common to steer the rear wheels or a single rear wheel, the front wheels being located below or close to a lift mast and not being steered. The radius of curvature when steering then results from the intersection of the axes of the steered rear wheel or the steered rear wheels with the axis of the front wheels. The intersection forms a cornering axis, around which the cornering takes place in which all wheels around this cornering axis ideally run with a radius on a curved path.

In a reach truck, the load weight is not predominantly compensated by a counterweight, but the center of gravity of the load spent by moving the lifting mast so far behind the front wheels that the vehicle is stable overall. To accomplish this, the front wheels are attached to the front end of load arms extending forwardly as load rollers. Again, however, the cornering axis is determined when cornering through the intersections of the axis of these load rollers in the load arms and the axis of a steered rear wheel.

In a tractor on the other hand, the front wheels are usually steered and the drive is via the rear wheels, which can not be hit.

There are now trucks known that represent combinations of the previously described vehicles, and therefore can take different operating conditions. Such a truck has, for example, a trailer hitch to Towing trailers, especially a trailer train of several trailers as a tugger train on. In addition, a load handling device can be used as a lifting device for storing and retrieving loads in shelves up to a certain height. For this purpose, it is for example possible to provide as a load-receiving device a hinged fork, which is folded up in a pure tractor operation. Furthermore, it is possible to provide for heavier loads load arms with additional support rollers that can be extended and, for example, can lift a pallet with an initial stroke, the weight of the pallet is already supported on the support rollers in these load arms to a large extent. Such a combined industrial truck can therefore be used in several modes, each of which corresponds to a conventional truck, such as a tractor, a counterbalance forklift or a reach truck.

An example of such a truck, which can be used in several functions and has extendable additional load arms with load rollers and folding forks, is in the EP 2 518 005 B1 the applicant discloses.

The problem with such a combined truck, that put very different demands on the steering behavior, depending on the manner of use. A disadvantage is in particular that results in an unusual driving behavior, as far as the steering has the cornering axis corresponding to a known type of truck on a prolonged strong axis and this deviates from the behavior of a conventional truck for a selected mode of operation. Also, turning the truck may require a relatively large amount of space, depending on the operating mode of the truck being used. With large or bulky recorded loads, the space requirement can unfavorably increase even further.

Finally, it is also desirable to optimize the space required for cornering when a truck bends into a storage lane of a racking.

It is also known to carry trucks as 4-way forklift, where 4 or 3 wheels can all be steered. These forklifts are mainly used for loads with large longitudinal extent, such as pipes, beams or the like laterally take and to transport in the longitudinal direction of these loads.

The WO 2008/141836 A1 discloses a tricycle, the wheels of which can be adjusted in three operating modes, a first in which the two front wheels are aligned in parallel and steered with the single tail wheel, a second in which all wheels are arranged transversely and the truck can move laterally and a third, in which all three wheels are aligned with a circle center within the base of the truck and thus allows a rotation on the spot.

EP 2 518 005 B1 discloses a truck with extendable load arms and hinged load forks.

The present invention has for its object to provide a method for steering control in a truck available, achieved by the operation of a corresponding and familiar steering behavior and the space required for cornering is minimized.

This object is achieved by a method for steering control in a truck with the features of independent claim 1. Advantageous developments of the invention are specified in the subclaims.

• Schlepper mit der Querlinie auf Höhe der Hinterräder
• Gegengewichtsgabelstapler mit der Querlinie auf Höhe der Vorderräder
• Schubmaststapler mit der Querlinie auf Höhe von Lastrollen in den ausgefahrenen Lastarmen

The object is achieved in that in a method for steering control in an industrial truck, in which all wheels of a front axle and a rear axle can be steered, and which has a trailer hitch and / or a hinged fork and / or extendable load arms, all wheels their axes are aligned to a common intersection as a curve axis of rotation, wherein the curve axis of rotation is set to a transverse line to the vehicle longitudinal axis depending on an operating mode of a controller and the operating mode can be selected from at least two of the following:

• Tractor with the transverse line at the level of the rear wheels
• Counterbalance forklift with the transverse line at the level of the front wheels
• Reach truck with the transverse line at the level of load rollers in the extended load arms

This always results in an optimal or familiar driving behavior, as far as the truck is controlled by a driver by an adjustment of the steering behavior is carried out to the active operating mode. It is not necessary to get used to changing the operating mode because the truck has a known behavior. Thus, when operating as a tractor only the front wheels are steered, when operating as a counterbalance forklift, the rear wheels steered so that the transverse line with the curve axis is in the axis of the two straight front wheels. If additional load arms are extended with load rollers, corresponding to a kind of reach truck, then all steered wheels of the front axle and rear axle are adjusted so that the transverse line falls on the axis of the load rollers. Depending on the desired radius of curvature to be traveled, the curve rotation axis then moves on the transverse line from infinity to the middle axis of the industrial truck with decreasing radius of curvature to be traveled. In the method described here, the controller selects between at least two or all described modes of operation. In principle, however, it is also conceivable to carry out a steering control in which the curve rotation axis is selected completely freely beyond the described positions on these transverse lines and independently of such a division into operating modes. In particular, this is conceivable in an autonomous, driverless vehicle in which, for example, a movement of the orientation of the truck and the cornering can be superimposed or, for example, an optimization of local routes can be done.

• Minimalradius mit der Querlinie auf halber Länge der Gesamterstreckung von Flurförderzeug einschließlich einer eventuellen aufgenommenen Last.

It can be selected as another operating mode:

• Minimum radius with the transverse line halfway along the total extent of the truck, including any eventual load.

The operating mode minimum radius can be selected and the curve rotation axis is placed in the operating mode minimum radius for rotation in place in the intersection of the transverse line with a vehicle longitudinal axis of the controller.

Viewed from above, an industrial truck with a load essentially forms a rectangle. The length and, in exceptional cases, the width of the rectangle can be determined by the size and shape of the load. The optimized, minimal space requirement between an outer Tangentenkreisbahn at this Rectangle over the outer corners and an inner Tangentenkreisbahn in the middle of the longitudinal extent is approximately, as far as the load is not laterally beyond the truck, with concentric Tangentenkreisbahnen whose center is located on a transverse line halfway along the length of the truck with the load. If the curve axis of rotation is placed on this transverse line, the result is an optimized, space-saving cornering, which enables optimized distances between the rack aisles. If the curve rotation axis is placed on this transverse line exactly in the middle of the rectangle, there is a rotation on the spot with minimal space requirements.

It is possible to select the operating mode minimum radius and the control of sensors obtain data on the dimensions of a recorded load.

Advantageously, the operating mode minimum radius can be selected and the control of a data connection, in particular from a network of a merchandise management system, obtained data on the dimensions of a load to be absorbed.

This allows the controller advantageously determine the geometry of the truck in supervision including the load and set a transverse line at half the longitudinal extent.

Advantageously, all steered wheels are driven.

This avoids that it comes to self-locking through the very free choice of curve rotation axis and sufficient driving forces can be transmitted even at large angles of impact.

In a development of the method, the industrial truck has a load fork and / or load arms and, for a transverse movement of the load fork and / or the load arms, the steered wheels are placed transversely to a longitudinal axis of the vehicle by the controller.

This can be done with an unfolded fork or extended load arms, in the latter as far as the load rollers permit, a transverse movement. It will no transverse thrust device required and the function of the transverse thrust can be realized solely by the described steering control method.

In a further development of the method, the truck can be operated autonomously without a driver.

In particular, when alternate operation is possible with both the driver and without the driver, the operating mode with a minimum radius in autonomous operation can be selected without unfamiliar driving behavior for a driver.

Fig. 1

ein erfindungsgemäßes Flurförderzeug in einem Betriebsmodus als Gegengewichtsgabelstapler,

Fig. 2

das Flurförderzeug in einem Betriebsmodus als Schlepper,

Fig. 3

das Flurförderzeug in einem Betriebsmodus als Schubmaststapler,

Fig. 4

das Flurförderzeug in einem Betriebsmodus "Minimalradius" mit einer Last,

Fig. 5

das Flurförderzeug in einem Betriebsmodus "Minimalradius" mit hochgeklappter Lastgabel und

Fig. 6

das Flurförderzeug in einem Betriebsmodus "Minimalradius" mit abgeklappter Lastgabel.

Further advantages and details of the invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures. This shows

Fig. 1

an industrial truck according to the invention in an operating mode as a counterbalance forklift,

Fig. 2

the truck in an operating mode as a tractor,

Fig. 3

the truck in an operating mode as a reach truck,

Fig. 4

the truck in a "minimum radius" operating mode with a load

Fig. 5

the truck in a mode of operation "minimum radius" with folded fork and

Fig. 6

the truck in a mode of operation "minimum radius" with folded fork.

The Fig. 1 shows an inventive truck 1 in an operating mode as a counterbalance forklift 2, in which a fork 3 is folded down. Front wheels 4 are spent in a straight position and are not steered. A single rear wheel 5 of the three-wheeled vehicle 1, is aligned so that a curve axis of rotation 6 moves depending on the radius of curvature to be traveled on a transverse line 7, which corresponds to the axis of the front wheels 4. This results for a driver the driving behavior of a known counterbalance forklift. 2

The Fig. 2 shows the truck 1 in an operating mode as a tractor 8, to which a trailer 9 is coupled. Here, the rear wheel 5 is held in the straight position and the transverse line 7 corresponds to the axis of the rear wheel 5. The front wheels 4 are aligned so that their intersection or the curve axis of rotation 6 moves on the transverse line 7. It thus results for the same truck alone the selection of the operating mode the driving behavior of a known tractor 8.

The Fig. 3 shows the truck 1 in an operating mode as a reach truck 10. Here are load arms 11 extended with load rollers 12. The axis of the load rollers 12 forms the transverse line 7. The axes of the front wheels 4 and 5 of the rear wheel are thereby aligned during cornering, that their intersection is located as a curve axis 6 on this transverse line 7. This results in the driving behavior of a known reach truck 10.

The Fig. 4 shows the truck 1 in a mode "minimum radius" with a load 13. By the load 13 results in the supervision of the truck 1 approximately an elongated rectangle. In order to achieve a minimum radius and track for cornering, the transverse line 7 is placed in the middle of the total length of truck 1 and load. For a given outer radius Ra for cornering results in a maximum inner radius Ri and thus a minimal space requirement by the arrangement of the cam axis of rotation 6. The required geometric conditions at the entrance, for example in a rack aisle can be optimized.

If a curve rotation axis 14 is placed in the center of the rectangle or the intersection of the transverse line 7 with a vehicle central axis, a rotation can take place with minimal space, as indicated by the arrow in the illustration of FIG Fig. 4 indicated.

The Fig. 5 shows the truck 1 in a "minimum radius" operating mode with the forklift tilted up and the cam pivot 14 at the center of the rectangle for minimum turnaround rotation.

The Fig. 6 shows the truck in a "minimum radius" operating mode with the fork 3 folded down and the cam pivot 14 at the center of an enclosing rectangle for rotation in the minimum footprint.

Claims (8)

1. Method for steering control in an industrial truck (1), in which all of the wheels of a front axle (4) and a rear axle (5) can be steered, and which has a trailer coupling and/or a load fork (3) which can be hinged down, and/or extendable load arms (11),
   characterized
   in that the axes of all of the wheels (4, 5) are aligned with a common intersecting point as a curve axis of rotation (6, 14), wherein the curve axis of rotation is set by a controller onto a transverse line (7) with respect to the longitudinal axis of the vehicle depending on the operating mode, and the operating mode can be selected from at least two of the following:

   - tractor (8) with the transverse line (7) level with the rear wheels (5)

   - counterbalance forklift truck (2) with the transverse line (7) level with the front wheels (4)

   - reach truck (10) with the transverse line (7) level with load rollers (12) in the extended load arms (11).
2. Method according to Claim 1,
   characterized
   in that the following can be selected as a further operating mode:

   minimum radius with the transverse line (7) over half the length of the entire extent of the industrial truck (1) including a load (13) which has possibly been picked up.
3. Method according to Claim 2,
   characterized
   in that the minimum radius operating mode can be selected, and, in the minimum radius operating mode, the curve axis of rotation (14) for rotation at the location is placed by the controller into the intersecting point of the transverse line (7) with a longitudinal axis of the vehicle.
4. Method according to Claim 2 or 3,
   characterized
   in that the minimum radius operating mode can be selected, and a controller receives data from sensors regarding the dimensions of a load (14) which has been picked up, in order to determine the geometry of the industrial truck in top view including the load and to fix a transverse line over half the longitudinal extent.
5. Method according to one of Claims 2 to 4,
   characterized
   in that the minimum radius operating mode can be selected, and a controller receives data from a data connection, in particular from a network of a merchandise management system, regarding the dimensions of a load (13) to be picked up, in order to determine the geometry of the industrial truck in top view including the load and to fix a transverse line over half the longitudinal extent.
6. Method according to one of Claims 1 to 5,
   characterized
   in that all of the steered wheels (4, 5) are driven.
7. Method according to Claim 6,
   characterized
   in that the industrial truck (1) has a load fork (3) and/or load arms (11) and, for a transverse movement of the load fork (3) and/or the load arms (11), the steered wheels (4, 5) are placed transversely with respect to a longitudinal axis of the vehicle by the controller.
8. Method according to one of Claims 1 to 7,
   characterized
   in that the industrial truck (1) can be operated autonomously without a driver.

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