Steering method for operating an industrial truck, and industrial truck

Abstract

The invention relates to a steering method for operating an industrial truck (1), wherein the industrial truck (1) has at least two front wheels (2.1, 2.2) and at least one rear wheel (3.1, 3.2), wherein a steering angle sensor (5) is actuated to initiate cornering around a steering pole (P), and the at least two front wheels (2.1, 2.2) and / or the at least one rear wheel (3, 3.1, 3.2) are steered, wherein the steering pole (P) is moved on a steering line (S) when the wheels (2.1, 2.2, 3, 3.1, 3.2) are steered, wherein a distance (L, Q) of the steering line (S) from the vehicle centre (M) of the industrial truck (1) is controlled. The invention also relates to an industrial truck (1) for carrying out such a steering method.

Description

[0001] Steering procedure for operating an industrial truck, industrial truck

[0002] The present invention relates to a steering method for operating an industrial truck and to an industrial truck for carrying out such a steering method.

[0003] Such steering methods are known in the art in a variety of different configurations. In particular, single-axle steering methods, in which the wheels of only one axle are steered, multi-axle steering methods, in which the wheels of more than one axle are steered, and all-wheel steering methods, in which all wheels can be steered, in particular each wheel individually.

[0004] To initiate a turn of an industrial truck, a turn radius is typically specified using a steering angle sensor, such as a steering wheel or joystick. One or more steerable wheels of the industrial truck then rotate or steer around an axis parallel to a vertical axis of the industrial truck, so that the steered wheels are no longer arranged parallel to a longitudinal or transverse direction of the industrial truck. A distinction can be made here between actively steerable wheels, namely wheels that have a steering gear or a steering drive for turning or steering the respective wheel or wheel suspension, and passively steerable wheels, namely those that are not motor-controlled for steering but are designed, for example, as trailing rollers. By positioning the steered wheels at an angle to the longitudinal or transverse direction of the industrial truck, the industrial truck executes a turn around a steering pole.

[0005] The steering center is the point at which orthogonal straight lines on the wheels of the industrial truck, which coincide with a respective rotational axis, can intersect. Advantageously, the straight lines of all steered wheels converge at a common steering center, thus essentially preventing slipping or friction.

[0006] Typically, the steering center of gravity is moved along a steering line when a turn is initiated. For example, when traveling straight ahead, all of the industrial truck's wheels are typically parallel to one another. The steering center of gravity is at infinity. If a turn is initiated by actuating a steering angle sensor, the steering center moves along the steering line from infinity towards the industrial truck. If one or more of the industrial truck's wheels do not steer when a turn is initiated, i.e. if one or more of the industrial truck's wheels do not rotate about an axis parallel to the vertical axis when a turn is initiated, the steering line becomes a straight line that intersects the center of the non-steered wheel.

[0007] It should be clear that the vertical axis, also called the z-axis, a longitudinal axis, also called the front-rear axis or x-axis, and a transverse axis of the industrial truck, also called the y-axis, are orthogonal to one another and typically intersect in the center of the vehicle. The longitudinal axis of the industrial truck intersects the center of the industrial truck and is typically arranged along the direction in which the industrial truck is operated in the main direction of travel. A transverse axis of the industrial truck intersects the longitudinal axis orthogonally in the center of the vehicle and is typically located in the plane along which the industrial truck can be moved perpendicularly or laterally to the main direction of travel, for example when the industrial truck is moved sideways.From the publication EP 2 956 350 B1, a three-wheeled industrial truck and a steering method applicable thereto are known. In longitudinal travel mode, also known as front-loader operation, two front wheels of the industrial truck are arranged non-steered or permanently parallel to the longitudinal axis to initiate cornering, and the vehicle is steered by turning a rear wheel of the industrial truck. Depending on the adjustment of the steering angle sensor, the rear wheel can be aligned obliquely to the longitudinal axis, in particular proportional to an adjustment angle of the steering angle sensor, so that the industrial truck rotates around a steering pole arranged on a steering line extending as a straight line through the two front wheels.

[0008] It has been shown that the steering methods known from the state of the art have disadvantages. For example, the inflexible guidance of the steering line makes it difficult to maneuver the industrial truck, particularly in narrow rack aisles. For example, if the industrial truck is equipped with a fork for picking up a load, such as pallets or the like, the operator must always consider the possibility of unintentional movement of the fork when steering and approaching the load.

[0009] It is therefore the object of the present invention to provide a steering method for operating an industrial truck and an industrial truck which do not have the disadvantages of the prior art and which make it possible to always optimize the driving and steering behavior of the industrial truck.

[0010] This object is achieved by a steering method having the features of claim 1 and by an industrial truck having the features of claim 12.

[0011] According to the invention, the steering method is particularly suitable for industrial trucks which - viewed in the longitudinal direction of travel - have at least two front wheels and at least one rear wheel. It is also conceivable for the industrial truck to have more than two front wheels and one rear wheel, for example two front wheels and two rear wheels. It is further conceivable for the industrial truck to have three or more front and / or rear wheels and / or one, two or more wheels on further axles which, with respect to the longitudinal axis of the industrial truck, are arranged in front of the front wheels, between the front and rear wheels, and / or behind the rear wheels. The present industrial truck can be designed, in particular, as a forklift truck.

[0012] A front wheel within the meaning of the present invention can be arranged in particular on that side region, in particular the front region, of the industrial truck which faces a load-handling device of the industrial truck. A rear wheel within the meaning of the present invention can be arranged in that region of the industrial truck which faces away from a load-handling device. If the load-handling device is provided approximately centrally on the industrial truck, a front wheel can be understood in particular as the wheel leading or arranged at the front in the main direction of travel of the industrial truck, and correspondingly, the rear wheel can be understood as the wheel trailing or arranged at the rear in the main direction of travel of the industrial truck.

[0013] To drive the industrial truck, at least one of the front and / or at least one rear wheel is driven, in particular in the circumferential direction. The drive of the wheels can be designed independently of one another; for example, each driven wheel can have its own drive motor, which can be controlled in particular independently of the other drive systems. The drive can be designed as an electric motor. However, it is also conceivable for the drive to have an internal combustion engine, a pneumatic motor, or a hydraulic motor. Furthermore, each drive can be individually controlled depending on a steering angle of the respective wheel and / or the industrial truck. Particularly preferably, only the two front wheels are driven to drive the industrial truck.

[0014] Furthermore, it is intended that all wheels of the industrial truck be steerable. It is conceivable that the industrial truck has actively steerable wheels, or steerable wheels driven for steering, and passively steerable wheels, or non-driven wheels, such as a trailing roller. The steerable wheels driven for steering can have a steering gear or each have its own steering drive, such as a steering drive motor for rotating the respective wheel about its vertical axis parallel to the vertical axis of the industrial truck. The steering drives can, in particular, be controlled independently of one another, so that each steerable wheel equipped with a steering drive can be steered individually. For the sake of clarity, reference is made here only to the "wheel" as the steerable component.Of course, it can also be provided that an entire wheel suspension with one or more individual wheels is rotated or steered around a vertical axis of the wheel suspension by means of a steering gear or steering drive.

[0015] To initiate cornering around the steering pole, the steering angle sensor is actuated. The steering angle sensor can be, for example, a steering wheel, a joystick, a slide control, a rotary control or a pedal arrangement. However, it is also conceivable for the steering angle sensor to be a sensor for automatically initiating cornering, for example along a predetermined path, or a computer which is configured to initiate pre-programmed or situation-dependent cornering. Upon actuation of the steering angle sensor, the at least two front wheels and / or the at least one rear wheel are steered, i.e. the at least two front wheels and / or the at least one rear wheel are each rotated about an axis parallel to the vertical axis of the industrial truck. It is particularly preferably provided that to initiate cornering, both the at least two front wheels and the at least one rear wheel are steered.

[0016] According to the invention, the distance between the steering line and the center of the industrial truck is controlled, in particular partially and / or fully automatically. This advantageously makes it possible to adapt the position of the steering line to suit the situation. The industrial truck behaves significantly differently when steering depending on the position of the steering line. If, for example, the steering line is on a front axle, also called the front wheel axle, the industrial truck remains relatively steady when cornering, whereas a load arranged on a fork of the industrial truck, for example, is swiveled over greater distances. If, however, the steering line intersects the fork of the industrial truck, for example, the load on the fork is swiveled less when cornering. It has therefore been found that the individual arrangement of the steering line can be particularly advantageous for certain situations.In particular, a partially or fully automatic control or shifting of the steering line depending on predefined criteria, such as, very generally speaking, "external conditions or circumstances," can be particularly advantageous. For example, the position of the steering line and / or a shifting of the steering line can occur depending on external environmental conditions, such as the current driving speed, road surface conditions, the intensity, in particular the speed of the movement of the steering angle sensor, and / or other conditions influencing the steering and steerability of the industrial truck. For this purpose, the industrial truck can be provided with detection devices for detecting the external environment and environmental conditions, such as a distance sensor and / or acceleration sensor, which can be monitored by a control device and thus taken into account for controlling the steering line.

[0017] Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0018] According to a preferred embodiment of the present invention, it is provided that the industrial truck can be operated in longitudinal travel mode and / or in transverse travel mode. In longitudinal travel mode within the meaning of the present invention, straight travel of the industrial truck along the longitudinal axis of the industrial truck is provided, in particular in the main direction of travel. In transverse travel mode within the meaning of the present invention, straight travel of the industrial truck along the transverse axis of the industrial truck is provided. According to this preferred embodiment, it is provided that in longitudinal travel mode the controlled distance is a longitudinal distance which corresponds to the distance of the steering line from the transverse axis. Furthermore, it is provided that in transverse travel mode the controlled distance corresponds to a transverse distance which is the distance of the steering line from the longitudinal axis.This advantageously makes it possible to control the steering line in the two important operating modes of longitudinal travel and transverse travel parallel to the respective straight-ahead travel direction, thus implementing situation-dependent changes in the position of the steering line adapted to the respective operating mode. According to a further preferred embodiment of the present invention, the distance is controlled depending on an operating parameter of the industrial truck. This advantageously makes it possible to adjust the position of the steering line (partially) automatically. An operator therefore does not have to worry about setting the steering line. This significantly simplifies operation of the industrial truck.

[0019] For this purpose, it is preferably provided that the operating parameter includes the geometry and / or the center of gravity of a loaded load. In this case, the geometry of the load is to be understood as meaning in particular the areal or volumetric extent of the load, in particular a load contour. For example, long loads such as profiles or beams regularly result in driving behavior of the industrial truck that is completely different from that of short, compact loads. Therefore, in this preferred embodiment, it is provided that the geometry of the loaded load is detected automatically or by manual input, and a steering line shift can occur depending on this parameter. For example, with particularly long loads, the steering pole of the industrial truck can be arranged in a geometric center of the load so that the industrial truck, together with the long load, can turn and maneuver in the smallest possible circle.By taking the center of gravity of the loaded load into account, it is recognized that, especially with heavy loads, it is sensible to align the steering line with the center of gravity of the load. This significantly reduces problems with the load's inertia when entering and negotiating a curve. Of course, a combination of considering the geometry and the center of gravity of the loaded load is also possible. In this case, the steering pole does not necessarily have to be located at the geometric center or the center of gravity of the load or the entire vehicle including the load, but can also be located somewhere in between, especially with asymmetrical loads.

[0020] Furthermore, it is preferably provided, alternatively or additionally, that the operating parameter includes the center of gravity of the industrial truck. This advantageously ensures that the inertia of the industrial truck is taken into account when initiating a curve and when negotiating a curve. In particular, it is provided that the operating parameter includes an overall center of gravity. The overall center of gravity takes into account the center of gravity of the industrial truck and the center of gravity of the load. The overall center of gravity is therefore the center of gravity of the loaded industrial truck.

[0021] According to a further preferred embodiment of the present invention, it is provided that the operating parameter comprises an angle of inclination of the industrial truck. The angle of inclination can, for example, be an angle of inclination around a front axle of the industrial truck. A front axle in the sense of the present invention intersects the at least two front wheels in their respective centers. This advantageously makes it possible to take into account a particularly high weight of a loaded load. However, it is also conceivable for the angle of inclination to be an angle of inclination around the transverse axis of the industrial truck. This advantageously makes it possible to take into account the shift in the steering line during upward or downward travel in longitudinal travel operation. Furthermore, it is conceivable for the angle of inclination to be an angle of inclination around the longitudinal axis of the industrial truck. This advantageously makes it possible to take into account the shift in the steering line during upward or downward travel in longitudinal travel operation.Downward travel in transverse travel mode must be taken into account. It is conceivable that the industrial truck could be equipped with a position sensor to take the inclination angle into account.

[0022] According to a further preferred embodiment of the present invention, the operating parameter includes an expected or already occurring swaying or shaking of the industrial truck, in particular during or due to uneven road surface conditions. "Expected" is understood in particular to mean that the industrial truck can comprise a detection device, in particular optical sensors, which detects, in particular scans, the ground conditions spatially in front of the industrial truck in the direction of travel, and based on the information obtained therefrom, operating parameters are determined for the expected swaying or shaking of the industrial truck when traveling over uneven ground.Based on this information, the steering line can be optimally controlled, especially to prevent the truck from skidding or rubbing against the ground and / or the load from slipping relative to the truck when negotiating curves. This can enable predictive driving.

[0023] According to a further preferred embodiment of the present invention, the operating parameter comprises an intensity, in particular speed, of the operation of the steering angle sensor of the industrial truck, wherein the operating parameter can be detected in particular by means of a magnetic detection device, such as a Hall sensor. For example, it can be provided that when the steering wheel is turned relatively quickly, the steering line is shifted toward the center of the industrial truck, and when the steering wheel is turned relatively slowly, the steering line is shifted away from the center of the industrial truck. This can result in advantageous properties, particularly in terms of driving dynamics.

[0024] According to a further preferred embodiment of the present invention, it is provided that the operating parameter comprises a maneuvering space available around the industrial truck. A maneuvering space within the meaning of the present invention is the space around the industrial truck that is available to the industrial truck for maneuvering. It is preferably provided that the available maneuvering space is detected by environmental sensors. Environmental sensors can be, for example, radar, lidar, ultrasonic, laser, or optical sensors. This advantageously makes it possible to adapt the distance of the steering line to the vehicle's center point to the external conditions. This enables comfortable driving on wide paths as well as easy maneuvering, for example in narrow shelf aisles.

[0025] Particularly preferably, it is provided that the operating parameter comprises a manual selection. The manual selection can be a selection between a reach truck mode and a front loader mode. In reach truck mode, the steering line in longitudinal travel operation is arranged such that it intersects the fork of the industrial truck. Particularly preferably, in reach truck mode, the steering line in longitudinal travel operation intersects the fork at the front end of the fork. In front loader mode, the steering line in longitudinal travel operation is arranged such that it is located between the fork and the at least one rear wheel. According to a further preferred embodiment of the present invention, it is provided that in longitudinal travel mode the longitudinal distance of the steering line from the transverse axis is regulated depending on the distance of the steering pole from the longitudinal axis and furthermore in transverse travel mode the transverse distance of the steering line from the longitudinal axis is regulated depending on the distance of the steering pole from the transverse axis.One possibility is, for example, that the longitudinal distance between the steering pole and the transverse axis increases as the transverse distance between the steering pole and the longitudinal axis decreases. In other words, the steering pole can be moved forward for small curve radii, for example. Another possibility is that the steering pole can be located on a fork or between the forks of the industrial truck, i.e. in the area of ​​the transported load, for small curve radii. This has the advantage that, particularly in confined spaces, rotation takes place around a point close to the load of the industrial truck. For example, the pivot point can be set at a corner of the load or at a center of gravity of the load. This enables the industrial truck to rotate around the load or around a corner point of the load. This is particularly advantageous when pivoting the industrial truck into a narrow aisle or load storage area to the side of the industrial truck.

[0026] Alternatively, the longitudinal distance of the steering pole from the transverse axis can also be reduced as the transverse distance of the steering pole from the longitudinal axis decreases. This pulls the steering pole toward the operator of the industrial truck when cornering with small radii. This allows the truck to rotate around its axis. This is particularly advantageous when reversing.

[0027] A further object for solving the initially stated problem is an industrial truck having a steering device configured to implement the steering method according to the invention by controlling the steering line. The steering device of the industrial truck according to the invention controls the distance of the steering line from the center of the industrial truck. The steering device can comprise the steering angle sensor, electrical components, hydraulic components, and / or a microcomputer. All advantages, features, and details of the steering method according to the invention mentioned in the description also relate to the industrial truck according to the invention.

[0028] Further details, features, and advantages of the invention will become apparent from the drawings and the following description of preferred embodiments with reference to the drawings. The drawings merely illustrate exemplary embodiments of the invention, which do not limit the scope of the invention.

[0029] They show:

[0030] Fig. 1 : a schematic view of an industrial truck according to an exemplary embodiment of the present invention in straight-ahead travel in longitudinal travel mode,

[0031] Fig. 2: a schematic view of the industrial truck shown in Figure 1 in

[0032] Straight-ahead driving in transverse mode,

[0033] Fig. 3: a schematic view of the industrial truck shown in Figure 1 in

[0034] Cornering in longitudinal driving mode,

[0035] Fig. 4: a schematic view of an industrial truck according to a further exemplary embodiment of the present invention during cornering in longitudinal travel mode,

[0036] Fig. 5: a schematic view of an industrial truck according to a further exemplary embodiment of the present invention during cornering in longitudinal travel mode,

[0037] Fig. 6: a schematic view of an industrial truck according to a further exemplary embodiment of the present invention in curve travel in transverse travel mode, Fig. 7: a schematic view of an industrial truck according to a further exemplary embodiment of the present invention in straight-ahead travel in longitudinal travel mode in reach mast mode and

[0038] Fig. 8: a schematic view of the industrial truck shown in Figure 6 in

[0039] Straight-ahead travel in longitudinal travel mode in front loader mode.

[0040] Figures 1 to 8 each show industrial trucks 1 according to an exemplary embodiment of the present invention. The industrial trucks 1 shown have a left front wheel 2.1 and a right front wheel 2.2 as well as a rear wheel 3 (Figures 1, 2, 6 and 7) or a left rear wheel 3.1 and a right rear wheel 3.2 (Figures 3, 4 and 5). The industrial trucks 1 furthermore each have a steering angle sensor 5, for example in the form of a steering wheel. For the sake of clarity, the steering angle sensor 5 is not shown in each of the figures shown here. Furthermore, the industrial trucks 1 have steering devices (not shown) which are configured to carry out the steering method according to the invention.

[0041] Figure 1 shows the industrial truck 1 traveling straight ahead in longitudinal travel mode. The front wheels 2.1, 2.2, and the rear wheel 3 are aligned parallel to a longitudinal axis X of the industrial truck 1. The longitudinal axis X is orthogonal to a transverse axis Y of the industrial truck 1 and intersects it at the center of the vehicle M.

[0042] The front axle V is arranged parallel to the transverse axis Y and centrally intersecting both front wheels 2.1 and 2.2, which are aligned for straight-ahead travel in longitudinal driving mode. The front axle V within the meaning of the present invention is not a mechanical component, but a geometric position designation.

[0043] The rear axle H is shown (Fig. 1) also arranged parallel to the transverse axis Y in longitudinal travel mode and centrally intersecting the rear wheel 3, which is aligned for straight-ahead travel in longitudinal travel mode. The rear axle H, also referred to as the rear wheel axle, also describes merely a geometric position designation within the scope of the invention and not a mechanical component. Figure 2 shows the industrial truck 1 shown in Figure 1 traveling straight ahead in transverse travel mode. The front wheels 2.1, 2.2 and the rear wheel 3 are aligned parallel to the transverse axis Y of the industrial truck 1.

[0044] In Figures 3 to 8, the rear axle H and the front axle V are not shown for the sake of clarity. In these figures, industrial trucks 1 can be seen cornering. The cornering is carried out around a steering center P. The steering center P is the intersection of straight lines that are orthogonal to the centers of all wheels 2.1, 2.2, 3, 3.1, 3.2 of the respective industrial truck 1. The curve radius is the distance between the steering center P and the vehicle center M. When traveling straight ahead, the steering center P is at infinity. If the steering angle sensor 5 is actuated, thereby initiating a curve, the steering center P moves from infinity along a steering line S towards the industrial truck 1.

[0045] According to the invention, a distance L, Q of the steering line S to the vehicle center M of the industrial truck 1 is regulated. This is indicated in Figures 1, 2, 6 and 7 by a double arrow on the steering line S. Figures 1 to 4 and 6 to 7 show industrial trucks 1 in longitudinal travel mode. In longitudinal travel mode, travel along the longitudinal axis X of the industrial truck 1 is provided when traveling straight ahead. The regulated distance of the steering line S to the vehicle center M of the industrial truck 1 is a longitudinal distance L, which corresponds to the distance L of the steering line S to the transverse axis Y. Figure 5 shows an industrial truck 1 in transverse travel mode when cornering. In transverse travel mode, travel along the transverse axis Y of the industrial truck 1 is provided when traveling straight ahead. The regulated distance of the steering line S to the vehicle center M in transverse travel mode is a transverse distance Q, which corresponds to the distance Q of the steering line S to the longitudinal axis L.

[0046] In the figures shown, the distance L, Q is controlled depending on an operating parameter of the industrial truck 1. Figure 3, for example, shows an industrial truck 1 with a load 4. The load 4 rests on a fork 6 of the industrial truck 1. In the embodiment shown here, the longitudinal distance L of the steering line S from the vehicle center M is controlled based on an operating parameter which includes the center of gravity 4.1 of the load 4 and the center of gravity 1.1 of the industrial truck 1. Using the center of gravity 4.1 of the load 4 and the center of gravity 1.1 of the industrial truck 1, an overall center of gravity 8 is calculated. In the example shown, the longitudinal distance L is controlled such that the steering line S runs through the overall center of gravity 8.

[0047] The industrial truck 1 shown in Figure 4 has environmental sensors 7, which detect the available maneuvering space and incorporate this into the operating parameters for controlling the position of the steering line S. In the illustration shown, the available maneuvering space is limited by rack walls 9. The industrial truck 1 controls the longitudinal distance L of the steering line S from the vehicle center point M such that the industrial truck 1 exhibits optimal steering behavior for the available maneuvering space.

[0048] The industrial truck 1 shown in Figure 5 controls the transverse distance Q of the steering line S to the longitudinal axis L in the transverse travel mode shown here such that the steering line S runs through the center of gravity 4.1 of the load 4 resting on the forks 6 of the industrial truck 1. The operating parameter for controlling the transverse distance Q here is therefore the center of gravity 4.1 of the load 4. In the example shown, both the center of gravity 4.1 of the load 4 and the vehicle center M lie on the longitudinal axis L of the industrial truck 1. The transverse distance Q of the steering line S to the longitudinal axis L is therefore zero. For the sake of clarity, the transverse distance Q and the longitudinal axis L are therefore not shown here.

[0049] Figures 6 and 7 show an industrial truck 1 in which the distance of the steering line S from the vehicle center M is controlled such that the operating parameter includes a manual selection. The manual selection here is a selection between a reach truck mode shown in Figure 6 and a front loader mode shown in Figure 7. In reach truck mode, the steering line S intersects the forks 6 of the industrial truck 1. If an operator of the industrial truck 1 selects the front loader mode instead of the reach truck mode, the steering line S is arranged further back, namely between the forks 6 and the rear wheel 3, for example on the front axle V.

[0050] Figure 8 shows an industrial truck 1 in which the distance of the steering pole P from the transverse axis Y is controlled as a function of the distance of the steering pole P from the longitudinal axis X. In the embodiment shown here, the steering line S shifts forward as the transverse distance Q decreases. This means that as the transverse distance Q decreases, the longitudinal distance L increases. This is particularly advantageous when maneuvering in very confined spaces.

[0051] It should be clear that the examples shown here of the design of the steering lines and their arrangement are not exhaustive. For example, the parabolic steering line shown as an example in Figure 8 can also be arranged with its straight section at the level of the front wheel axle V. In this case, it can advantageously be provided that the steering line S never crosses the center of a front wheel 2.1, 2.2 or a rear wheel 3, 3.1, 3.2, but always runs past them at a laterally spaced distance. As a result, the industrial truck 1, for example in longitudinal travel mode when turning from straight-ahead travel, is initially steered exclusively via the rear wheel 3. The front wheels 2.1, 2.2 initially remain unsteered, in particular aligned parallel to the longitudinal axis X.From a predefined steering angle of the rear wheel 3 relative to the longitudinal axis X, preferably 40°, the steering pole P is deflected or offset laterally next to the front wheel axis V by the curved shape of the steering line S, so that the steering pole P does not pass through the center of one of the front wheels 2.1, 2.2 upon further steering. As a result, the front wheels 2.1, 2.2 are only steered from a predefined steering angle, in particular of the rear wheel 3. The front wheels 2.1, 2.2 can always maintain the rotational movement in the same direction, controlled by drive motors (not shown) for rotating the wheels.

[0052] All details and features shown above for longitudinal operation also apply mutatis mutandis to transverse operation and vice versa. Reference symbols:

[0053] 1 industrial truck

[0054] 1.1 Center of gravity of the industrial truck

[0055] 2.1 left front wheel

[0056] 2.2 right front wheel

[0057] 3 rear wheel

[0058] 3.1 left rear wheel

[0059] 3.2 right rear wheel

[0060] 4 Last

[0061] 4.1 Center of gravity of the load

[0062] 5 steering angle sensors

[0063] 6 forks

[0064] 7 environmental sensors

[0065] 8 Overall focus

[0066] 9 Shelving unit

[0067] H rear axle

[0068] L Longitudinal distance

[0069] M Vehicle center

[0070] P Steering pole

[0071] Q Transverse distance

[0072] S steering line

[0073] T Vehicle length

[0074] V front axle

[0075] X Longitudinal axis

[0076] Y transverse axis

Claims

Patent claims:

1. Steering method for operating an industrial truck (1), wherein the industrial truck (1) has at least two front wheels (2.1, 2.2) and at least one rear wheel (3.1, 3.2), wherein a steering angle sensor (5) is actuated to initiate cornering around a steering pole (P) and the at least two front wheels (2.1, 2.2) and / or the at least one rear wheel (3, 3.1, 3.2) are steered, wherein when steering the wheels (2.1, 2.2, 3, 3.1, 3.2) the steering pole (P) is moved on a steering line (S), wherein a distance (L, Q) of the steering line (S) to the vehicle center (M) of the industrial truck (1) is regulated.

2. Steering method according to claim 1, characterized in that the industrial truck (1) can be operated in a longitudinal travel mode and / or in a transverse travel mode, wherein in longitudinal travel mode a straight-ahead travel of the industrial truck (1) is arranged along a longitudinal axis (X) of the industrial truck, wherein in transverse travel mode the straight-ahead travel of the industrial truck (1) is arranged along a transverse axis (Y) of the industrial truck (1), wherein the longitudinal axis (X) and the transverse axis (Y) are arranged orthogonally to one another and intersect in the vehicle center (M), wherein in longitudinal travel mode the controlled distance (L) is a longitudinal distance (L), which is the distance (L) of the steering line (S) to the transverse axis (Y), and wherein in transverse travel mode the controlled distance (Q) is a transverse distance (Q), which is the distance (Q) of the steering line (S) to the longitudinal axis (X).

3. Steering method according to one of claims 1 or 2, characterized in that the distance (L, Q) is controlled depending on an operating parameter of the industrial truck (1).

4. Steering method according to claim 3, characterized in that the operating parameter comprises the geometry and / or the center of gravity (4.1) of a loaded load (4).

5. Steering method according to one of claims 3 to 4, characterized in that the operating parameter comprises the center of gravity (1.1) of the industrial truck (1), wherein the operating parameter preferably comprises an overall center of gravity (S), wherein the overall center of gravity (8) is the center of gravity of the industrial truck (1) with the loaded load (4).

6. Steering method according to one of claims 3 to 5, characterized in that the operating parameter comprises an angle of inclination of the industrial truck (1).

7. Steering method according to one of claims 3 to 6, characterized in that the operating parameter comprises an expected or occurring swaying or shaking of the industrial truck (1), in particular in the case of an uneven road surface, wherein the operating parameter can be detected in particular by means of an optical sensor.

8. Steering method according to one of claims 3 to 7, characterized in that the operating parameter comprises an intensity, in particular speed, of the operation of the steering angle sensor (5) of the industrial truck (1), wherein the operating parameter can be detected in particular by means of a magnetic detection device, such as a Hall sensor.

9. Steering method according to one of claims 3 to 8, characterized in that the operating parameter comprises the maneuvering space available around the industrial truck (1), wherein the available maneuvering space is preferably detected by environmental sensors (7). Steering method according to one of claims 3 to 9, characterized in that the operating parameter comprises a manual selection, wherein the manual selection preferably comprises the selection between a reach truck mode, in which the steering line (S) intersects a fork (6) of the industrial truck (1), and a front loader mode, in which the steering line (S) is arranged between the fork (6) and the at least one rear wheel (3, 3.1, 3.2). Steering method according to one of claims 3 to 10, characterized in that in longitudinal travel mode, the longitudinal distance (L) of the steering line (S) from the transverse axis (Y) is regulated as a function of the distance of the steering pole (P) from the longitudinal axis (X) and / or wherein in transverse travel mode, the transverse distance (Q) of the steering line (S) from the longitudinal axis (X) is regulated as a function of the distance of the steering pole (P) from the transverse axis (Y).Industrial truck (1), characterized in that the industrial truck (1) has a steering device which is configured to carry out a steering method according to one of the preceding claims by regulating the steering line (S).

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