Steering method for operating an industrial truck, and industrial truck

Abstract

The invention relates to steering method for operating an industrial truck (1). The industrial truck (1) has at least two front wheels (2.1, 2.2) and at least one rear wheel (3.), wherein in order to initiate a cornering drive about a steering pole (P), an input value (E) is entered on a steering angle transmitter (5), and the at least two front wheels (2.1, 2.2) and / or the at least one rear wheel (3, 3.2, 3.2) are steered. The steering pole (P) is moved on a steering line (S) by a steering distance (∆Q), and the input value (E) is linked to the steering distance (∆Q) via a steering ratio, said steering ratio being dynamically regulated. The invention additionally relates to an industrial truck (1).

Description

[0001] HUBTEX Maschinenbau GmbH & Co. KG Werner-von-Siemens Str. 8 36041 Fulda

[0002] Steering procedure for operating an industrial truck, industrial truck

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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 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. The shifting of the steering pole is typically caused by an input on the steering angle sensor.An input to the steering angle sensor can, for example, be a rotation of the steering wheel by a certain angle or a movement of a joystick by a certain distance. The entered angle or distance corresponds to an input value, which is further processed and converted into a corresponding shift of the steering pole along the steering line by a certain steering distance.

[0009] The conversion of the input value is usually linked to the steering travel using a steering ratio. In general, the steering ratio behaves like a factor whose multiplication by the input value yields the steering travel.

[0010] 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 reach truck mode, 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, in particular proportional to an adjustment angle of the steering sensor, the rear wheel can be aligned obliquely to the longitudinal axis, 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.

[0011] It has been shown that the steering methods known from the state of the art have disadvantages. For example, it has been shown that different situations during industrial truck operation place different demands on the operator. For example, during a long straight journey an operator must primarily concentrate on the situation in front of the truck without requiring highly precise steering of the industrial truck. The operator can roughly guide the steering sensor here. Other situations, however, require significantly more steering effort. For example, picking up or unloading a load in a narrow rack aisle. In these cases the operator must operate the steering sensor particularly intensively. This can be relatively strenuous for the operator.

[0012] 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 in particular make it possible to design the driving and steering behavior of the industrial truck in a particularly comfortable and optimal manner for the operator.

[0013] This object is achieved by a steering method having the features of claim 1 and by an industrial truck having the features of claim 13.

[0014] According to the invention, the steering method is particularly suitable for industrial trucks which - viewed in the longitudinal travel orientation - 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.

[0015] 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 to be 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 to be the wheel trailing or arranged at the rear in the main direction of travel of the industrial truck. To drive the industrial truck, at least one of the front and / or rear wheels is driven, in particular in the circumferential direction.The drive of the wheels can be configured independently of one another. For example, each driven wheel can have its own drive motor, which can be controlled independently of the other drive systems. The drive can be configured 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 the 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.

[0016] 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.

[0017] 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 entry of an input value at 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 around an axis parallel to the vertical axis of the industrial truck. This causes the steering pole to shift along the steering line by one steering value.It is particularly preferred that both the at least two front wheels and the at least one rear wheel are steered to initiate cornering.

[0018] A vertical axis of the industrial truck within the meaning of the present invention intersects a vehicle center and is arranged orthogonal to the longitudinal axis and orthogonal to the transverse axis. The vertical axis is further arranged orthogonal to the plane in which the industrial truck is intended to transport a load. A longitudinal axis of the industrial truck within the meaning of the present invention intersects the vehicle center of the industrial truck and is arranged along the direction in which the industrial truck is moved to load or unload a load and lies in the plane along which the industrial truck is intended to convey a load. A transverse axis of the industrial truck within the meaning of the present invention is arranged orthogonal to the longitudinal axis and orthogonal to the vertical axis and intersects the longitudinal axis in the vehicle center.

[0019] It is particularly preferred that both the at least two front wheels and the at least one rear wheel are steered to initiate cornering. It is provided that all wheels of the industrial truck are designed to be steerable. It is conceivable for the industrial truck to have steerable wheels that are driven for steering and non-driven wheels for steering. The steerable wheels that are driven for steering can each have their own steering drive motor for rotating the respective wheel about a wheel 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 provided with a steering drive can be steered individually.When initiating a curve from straight-ahead travel, the steering pole is moved along a steering curve from infinity towards the industrial truck by the steering travel, which is proportional to the input value on the steering angle sensor. The steering travel is calculated from the input value multiplied by the steering ratio. The steering ratio therefore links the steering travel with the input value. According to the invention, the steering ratio is dynamically controlled, in particular partially and / or fully automatically. This advantageously makes it possible to adapt the steering behavior of the industrial truck to the current operating situation of the industrial truck. Dynamically controlled in the sense of the present invention means that the steering ratio is adaptable during operation of the industrial truck and can be adapted in particular depending on predefined criteria during operation of the industrial truck.In particular, dynamic and / or partially or fully automatic control or ratio depending on - very generally speaking - "external conditions or circumstances" can be particularly advantageous. For example, the steering ratio can be dependent on external environmental conditions, such as the current weight of a loaded load, the center of gravity of the load, the angle of inclination of the industrial truck, a maneuvering space, a driving speed, a road surface condition, an intensity, in particular the speed of the movement of the steering angle sensor and / or other circumstances influencing the steering and steerability of the industrial truck.For automatic control, the industrial truck can be equipped with detection devices for detecting the external environment and ambient conditions, such as a distance sensor and / or acceleration sensor. These devices can be monitored by a control device and thus taken into account for controlling the steering line. Furthermore, the steering ratio can vary across the entire length of the steering line. For example, when turning from a straight-ahead position and the steering center is sufficiently far away from the industrial truck, a small ratio can be applied, for example, when turning the steering wheel from a straight-ahead position up to an angle of + / -10. 0, whereas when turning from a steered position, for example, when turning the steering wheel to an angle of more than 10°, a stronger transmission ratio is applied, allowing the wheels to be steered more quickly. Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0020] According to a preferred embodiment of the present invention, the steering ratio is controlled as a function of an operating parameter of the industrial truck. An operating parameter of the industrial truck within the meaning of the present invention can be an external influence. For example, it is conceivable that the external influence is caused by the operation of the industrial truck. However, it is also conceivable that the external influence is caused by environmental conditions. An operating parameter of the industrial truck within the meaning of the present invention can alternatively or additionally be a parameter which is determined by the structure of the industrial truck. In particular, it is advantageously possible to control the steering ratio in a (partially) automated manner. An operator does not have to worry about setting the steering ratio. This significantly simplifies the operation of the industrial truck.

[0021] For this purpose, it is preferably provided that the operating parameter comprises a vehicle speed. A vehicle speed in the sense of the present invention is the speed at which the industrial truck is moved and / or is to be moved. For example, it is conceivable that the vehicle speed is the current speed of the industrial truck along the plane in which the industrial truck is intended to transport a load. However, it is also conceivable that the vehicle speed is a target speed at which an operator intends to drive the industrial truck along the plane in which the industrial truck is intended to transport a load. For this purpose, it is conceivable that the travel speed is linked to a target speed value which is specified by an operator of the industrial truck, for example by actuating an accelerator pedal.Preferably, the steering ratio is controlled such that the steering ratio is high at low travel speeds and low at high travel speeds. This advantageously makes it possible for the steering angle sensor to only need to be moved slightly at low travel speeds, for example when maneuvering. Furthermore, this advantageously prevents unintentional movements of the steering angle sensor from leading to unwanted steering reactions when the industrial truck is traveling at high speeds. It is conceivable that the steering ratio is adjusted linearly with the travel speed. However, it is also conceivable that the steering ratio is adjusted gradually with the travel speed.

[0022] 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, the industrial truck travels straight ahead along the longitudinal axis of the industrial truck. In transverse travel mode, the industrial truck travels straight ahead along the transverse axis of the industrial truck. In longitudinal travel mode, the operating parameter includes a transverse distance of the steering pole from the longitudinal axis. In transverse travel mode, the operating parameter includes a longitudinal distance of the steering pole from the transverse axis. The steering ratio is controlled in particular such that the steering ratio in longitudinal travel mode is higher for small transverse distances than for large transverse distances and that the steering ratio in transverse travel mode is higher for small longitudinal distances than for large longitudinal distances.In other words, an additional input to the steering angle sensor by the operator during tight cornering has a greater influence on cornering than an input to the steering angle sensor by the operator during cornering with a large radius or when driving straight ahead. It is conceivable that the steering ratio is adjusted linearly with the lateral or longitudinal offset. However, it is also conceivable that the steering ratio is adjusted gradually with the lateral or longitudinal offset.

[0023] It is particularly preferably provided that the operating parameter comprises a condition of the roadway on which the industrial truck is traveling. In particular, it is provided that the operating parameter comprises deviations in the evenness of the roadway. Deviations in the evenness of the roadway within the meaning of the present invention comprise the depth or height of unevenness in the roadway and are therefore also referred to as unevenness. It is preferably provided that the steering ratio is controlled such that in the case of severe deviations in evenness and / or a high number of evenness deviations, the steering ratio is lower than in the case of less severe deviations in evenness and / or a lower number of evenness deviations. This advantageously makes it possible for accidental displacement of the steering angle sensor on poor road surfaces to prevent strong, unwanted steering movements of the industrial truck.It is conceivable that the intensity and / or number of evenness deviations are detected by a vibration sensor of the industrial truck. Furthermore, it can be provided that 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 this case to mean, in particular, 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, operating parameters relating to the expected swaying or shaking of the industrial truck when traveling over uneven ground are determined.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.

[0024] It is particularly preferred that the operating parameter comprises the geometry and / or the center of gravity of a loaded load. In this case, the geometry of the load is to be understood in particular as 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, particularly with asymmetrical loads.

[0025] 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, also called front wheel axle, within the meaning of the present invention intersects the at least two front wheels at their respective centers. This advantageously allows a particularly high weight of a loaded load to be taken into account. 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 allows the shift in the steering line during upward or downward travel in longitudinal travel operation to be taken into account. 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 allows the shift in the steering line during upward or downward travel in longitudinal travel operation to be taken into account.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.

[0026] 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.

[0027] According to a further preferred embodiment of the present invention, the operating parameter comprises an input speed at which the input value is entered at the steering angle sensor. An input speed in the sense of the present invention is the change in the input value at the steering angle sensor over time. If the steering angle sensor is a steering wheel, for example, the steering ratio depends on the speed at which the steering wheel is turned. Preferably, the steering ratio is controlled such that the steering ratio is lower at low input speeds than at high input speeds. This allows the operator a convenient and intuitive way of adjusting the steering ratio. It is conceivable that the steering ratio is adjusted linearly with the input speed. However, it is also conceivable that the steering ratio is adjusted stepwise with the input speed.

[0028] Particularly preferred is an embodiment in which the operating parameter includes 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 for the steering ratio to be adapted to the external conditions. In particular, it is provided that the steering ratio is lower for a relatively large possible maneuvering space than for a relatively small possible maneuvering space. This therefore enables comfortable driving on wide paths as well as easy maneuvering, for example in narrow shelf aisles.

[0029] According to a further preferred embodiment of the present invention, the industrial truck comprises a loading device, in particular a fork, which is intended to pick up a load to be transported. The loading device is raised to a lifting height. For this purpose, the operating parameter is provided to include the lifting height. In particular, the steering ratio is controlled such that the steering ratio is lower at a lower lifting height than at a higher lifting height. This advantageously makes it easy to set a higher steering ratio for loading or unloading the load to be transported on shelves than, for example, for a transport journey which follows loading or unloading. This makes operating the industrial truck significantly easier. It is conceivable for the steering ratio to be adjusted linearly with the lifting height.It is also conceivable that the steering ratio is adjusted gradually with the lifting height.

[0030] Preferably, the operating parameter also includes a manual selection. In other words, the operator can adjust the steering ratio to their personal preferences while the industrial truck is in operation. This could be done via a quick adjustment. For example, it is conceivable that the steering ratio can be adjusted in steps or continuously using a controller.

[0031] A further object for solving the problem posed initially is an industrial truck having a steering device configured to implement the steering method according to the invention by controlling the steering ratio. The steering device of the industrial truck according to the invention effects the control of the steering ratio. The steering device can comprise the steering angle sensor, electrical components, hydraulic components, and / or a microcomputer.

[0032] All advantages, features and details of the steering method according to the invention mentioned in the description text also relate to the industrial truck according to the invention.

[0033] 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 inventive concept. They show:

[0034] 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,

[0035] Fig. 2: a schematic view of the industrial truck shown in Figure 1 in

[0036] Straight-ahead driving in transverse mode,

[0037] Fig. 3: a schematic view of the industrial truck shown in Figure 1 in

[0038] Cornering in longitudinal driving mode,

[0039] Fig. 4: a schematic view of an industrial truck according to a further exemplary embodiment of the present invention in cornering in transverse travel mode and

[0040] Fig. 5: a schematic view of an industrial truck according to a further exemplary embodiment of the present invention during cornering in longitudinal travel operation.

[0041] Figures 1 to 5 each show industrial trucks 1 according to exemplary embodiments 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 to 3) or a left rear wheel 3.1 and a right rear wheel 3.2 (Figures 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.

[0042] 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

[0043] Transverse axis Y of the industrial truck 1 and intersects it in the vehicle center M.

[0044] 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.

[0045] Figures 3 to 5 show the industrial trucks 1 cornering. Each cornering is performed 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, and 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.

[0046] Figures 3 and 4 show how the steering angle sensor 5 is actuated during cornering. The steering angle sensor 5 is designed as a steering wheel here. By turning the steering wheel, the operator of the industrial truck 1 enters an input value E (represented here by the arrows above the steering angle sensor 5). In the exemplary embodiment shown, the input value E is an angle by which the steering wheel is turned. Upon input of the input value E, the steering pole P shifts along the steering line S by a steering distance AQ. The steering pole P shifted by the steering distance AQ is designated P' here. The input value E is linked to the steering distance AQ via a steering ratio. Multiplying the input value E by the steering ratio results in the steering distance AQ.

[0047] According to the invention, the steering ratio is dynamically controlled. This means that the steering ratio is adjusted during operation of the industrial truck 1. In the industrial trucks 1 shown here, the steering ratio is controlled depending on an operating parameter of the industrial truck 1. The operating parameter can include, for example, a vehicle speed. Furthermore, the operating parameter can include a transverse distance Q of the steering pole P from the longitudinal axis X during longitudinal operation of the industrial truck 1 and a longitudinal distance L of the steering pole P from the transverse axis Y during transverse operation of the industrial truck 1. Furthermore, the operating parameter can include an input speed at which the input value E is entered on the steering angle sensor 5 and / or set manually.

[0048] The industrial truck 1 shown in Figure 3 has a vibration sensor 8. The vibration sensor 8 detects flatness deviations 10 of the roadway on which the industrial truck 1 travels. The detected flatness deviations 10 are also incorporated into the operating parameters, which influence the steering ratio.

[0049] Figures 4 and 5 depict a load 4 being transported by the industrial truck 1. The load 4 is picked up by a loading device 6, in the illustrated embodiments, a fork. The loading device 6 is raised to a lifting height. In the exemplary embodiments shown in these figures, the operating parameter also includes the lifting height, so that the lifting height is included in the control of the steering ratio.

[0050] Figure 5 shows an industrial truck 1 equipped with environmental sensors 7. The environmental sensors 7 detect the available maneuvering space, which is defined by the rack walls 9. In the embodiment shown in Figure 5, the operating parameter includes the available maneuvering space. Thus, the steering ratio is controlled depending on the available maneuvering space.

[0051] The details and features shown here for longitudinal travel also apply mutatis mutandis to transverse travel and vice versa.

[0052] Reference list:

[0053] 1 industrial truck

[0054] 2.1 left front wheel

[0055] 2.2 right front wheel

[0056] 3 rear wheel

[0057] 3.1 left rear wheel

[0058] 3.2 right rear wheel

[0059] 4 Last

[0060] 5 steering angle sensors

[0061] 6 Charging device

[0062] 7 environmental sensors

[0063] 8 Vibration sensor

[0064] 9 Shelving unit

[0065] 10 flatness deviations

[0066] E Input value

[0067] L Longitudinal distance

[0068] M Vehicle center

[0069] P, P' steering pole

[0070] Q Transverse distance

[0071] AQ steering path

[0072] S steering line

[0073] X Longitudinal axis

[0074] Y transverse axis

Claims

Patent claims: 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 an input value (E) is input to a steering angle sensor (5) 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 along a steering line (S) by a steering path (AQ), wherein the input value (E) is linked to the steering path (AQ) via a steering ratio, wherein the steering ratio is controlled, in particular dynamically controlled. Steering method according to claim 1, characterized in that the steering ratio is controlled as a function of an operating parameter of the industrial truck (1).Steering method according to claim 2, characterized in that the operating parameter comprises a vehicle speed, wherein the steering ratio is controlled such that the steering ratio is high at low vehicle speeds and that the steering ratio is low at high vehicle speeds.Steering method according to one of claims 2 to 3, characterized in that the industrial truck (1) can be operated in a longitudinal travel mode and / or in a transverse travel mode, wherein in the 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 the 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 orthogonal to one another and intersect in the vehicle center (M), wherein in the longitudinal travel mode the operating parameter comprises a transverse distance (Q) of the steering pole (P) from the longitudinal axis (X), wherein in. In transverse driving mode, the operating parameters include a longitudinal distance (L) of the steering pole (P) from the transverse axis (Y), the steering ratio being controlled in particular such that the steering ratio in longitudinal driving mode is higher at small transverse distances (Q) than at large transverse distances (Q) and that the steering ratio in transverse driving mode is higher at small longitudinal distances (L) than at large longitudinal distances (L).

5. Steering method according to one of claims 2 to 4, characterized in that the operating parameter comprises a condition of the roadway on which the industrial truck (1) is driven, wherein the operating parameter in particular comprises evenness deviations of the roadway, wherein the steering ratio is in particular controlled such that in the case of severe evenness deviations and / or a high number of evenness deviations, the steering ratio is lower than in the case of less severe evenness deviations and / or a lower number of evenness deviations.

6. Steering method according to one of claims 2 to 5, characterized in that the operating parameter comprises the geometry and / or the center of gravity (4.1) of a loaded load (4).

7. Steering method according to one of claims 2 to 6, characterized in that the operating parameter comprises an angle of inclination of the industrial truck (1).

8. Steering method according to one of claims 2 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. Steering method according to one of claims 2 to 8, characterized in that the operating parameter comprises an input speed at which the input value (E) is input at the steering angle sensor (5), wherein the steering ratio is controlled in particular such that the steering ratio is lower at low input speeds than at high input speeds. Steering method according to one of claims 2 to 9, characterized in that the operating parameter comprises a maneuvering space available around the industrial truck, wherein the available maneuvering space is preferably detected by environmental sensors (7), wherein the steering ratio is controlled in particular such that the steering ratio is lower when there is a lot of available maneuvering space than when there is less available maneuvering space.Steering method according to one of claims 2 to 10, characterized in that the industrial truck (1) comprises a loading device (6), in particular a fork, which is intended to receive a load (4) to be transported, wherein the loading device (6) is raised to a lifting height, wherein the operating parameter comprises the lifting height, wherein the steering ratio is controlled in particular such that the steering ratio is lower at a lower lifting height than at a higher lifting height. Steering method according to one of claims 2 to 11, characterized in that the operating parameter comprises a manual selection. 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 controlling the steering ratio.

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