PTO-guided industrial truck

Abstract

Tiller-steered industrial truck (1) with a tiller (8) pivotable about a vertical axis (7) and a drive motor, wherein the maximum travel speed (V) max ) of the industrial truck (1) is controllable depending on the swivel angle (α) of the tiller (8) about the vertical axis (7), wherein in a first swivel range (S1) about the straight-ahead position of the tiller (8) the industrial truck (1) travels at a maximum speed (V max ) is operable and in a second pivoting range (S2), which includes the maximum pivoting position of the drawbar (8), is operable with a reduced maximum speed (V1), characterized in that a transition range (S3) is formed between the first pivoting range (S1) and the second pivoting range (S2), in which the maximum driving speed (V) max) can be continuously varied with the pivot angle (α) of the drawbar (8), whereby in the transition range (S3) the maximum driving speed (V) max ) is linearly variable with the swivel angle (α) of the drawbar (8), wherein the first swivel range (S1) has a swivel angle (α) of the drawbar (8) in the range of + / - 50 0 up to + / - 70 0 , especially + / - 60 0 , starting from the straight-ahead position of the drawbar (8) and the second pivot range (S2) encompasses a pivot angle (a) of the drawbar (8) in the range of 0 0 up to 15 0 before the maximum pivot position of the drawbar (8) includes, in particular 10 0 before the maximum pivot position of the drawbar (8).

Description

[0001] The invention relates to a tiller-steered industrial truck with a tiller pivotable about a vertical axis and a drive motor, wherein the maximum travel speed of the industrial truck is controllable depending on the pivot angle of the tiller about the vertical axis, wherein in a first pivot range about the straight-ahead position of the tiller the industrial truck can be operated at a maximum travel speed and in a second pivot range, which includes the maximum pivot position of the tiller, can be operated at a reduced maximum speed.

[0002] Industrial trucks of this type are often designed as electrically powered low-lift or high-lift pallet trucks, operated by a pedestrian. A drive wheel of the truck, powered by a drive motor, is directly or indirectly connected to the tiller, allowing the operator to steer the truck by pivoting the tiller around a vertical axis. The pivot angle of the tiller determines the steering angle of the drive wheel.

[0003] To operate the various functions of the industrial truck, in particular the drive system, the tiller is pivoted downwards from an at least approximately vertical out-of-service position.

[0004] In certain operating situations, for example, if the operator performs an abrupt steering maneuver with a sharp steering angle by quickly moving the tiller during operation at high speed, this can lead to unsafe operating conditions for the industrial truck, especially when the truck is loaded with a load.

[0005] To avoid such unsafe operating conditions, it is already known to limit the maximum travel speed to a fixed reduced value when a certain steering angle of the tiller is exceeded. Particularly when operating at maximum travel speed, this can lead to a jerky and therefore undesirable deceleration of the industrial truck when the speed transitions from the maximum to the reduced value due to a corresponding steering movement of the tiller. Similarly, when transitioning from the reduced value to the maximum travel speed, a sudden acceleration of the industrial truck can occur when the tiller is steered back towards the straight-ahead position.Such abrupt braking and acceleration is perceived as disruptive by the operator of a tiller-steered industrial truck and can lead to dangerous operating conditions, especially at high tiller steering angles and when maneuvering the industrial truck in confined spaces, where the operator is at a small lateral distance to the industrial truck due to the tiller's position to the side.

[0006] WO 2006 / 113 510 A2 discloses a generic tiller-steered industrial truck with the features of the preamble of claim 1.

[0007] The article Butzke, J.: “Forklift with safe cornering”, Lifting equipment and conveying equipment, Berlin 43, 2003, 7-8, pages 340-341 reveals a counterbalance forklift in which the driving speed of the forklift is reduced when cornering depending on the steering angle.

[0008] The article “Intelligent Trio”, Fördermittel Journal, 35th year, April 2003, pages 44-45 reveals a pedestrian-operated low-lift pallet truck in which the speed is automatically reduced when cornering.

[0009] The invention is therefore based on the objective of providing a tiller-steered industrial truck of the type mentioned above, with which operational safety and operational behavior can be improved.

[0010] This problem is solved according to the invention by forming a transition area between the first pivoting area and the second pivoting area, in which the maximum driving speed can be continuously changed with the pivoting angle of the drawbar, wherein in the transition area the maximum driving speed can be changed linearly with the pivoting angle of the drawbar, wherein the first pivoting area has a pivoting angle of the drawbar in the range of + / -50 0 up to + / - 70 0, especially + / - 60 0 , starting from the straight-ahead driving position of the drawbar, and the second swivel range encompasses a swivel angle of the drawbar in the range of 0 0 up to 15 0 before the maximum pivot position of the drawbar includes, in particular 10 0The invention encompasses the area before the tiller reaches its maximum pivot position. According to the invention, a transition zone is thus formed between the first pivot range of the tiller around the straight-ahead position, in which the industrial truck can be operated at its maximum travel speed, and the second pivot range in the area of ​​the tiller's maximum pivot position and thus maximum steering angle, in which the industrial truck operates at its reduced maximum speed. In this transition zone, the maximum travel speed, and thus the maximum speed of the industrial truck, is variable and controlled depending on the tiller's pivot position and thus its steering angle. Within this transition zone, the maximum speed is continuously adjusted to the tiller's pivot angle and thus its steering angle. The larger the tiller's pivot angle and thus the steering angle becomes, the more the maximum travel speed is reduced.The change in maximum speed is continuous, ensuring that no jerky acceleration or deceleration of the industrial truck is triggered when the tiller is pivoted and thus when steering the industrial truck, resulting in high operational reliability of the industrial truck with pleasant operating characteristics and improved ergonomics for the operator, especially at high steering angles and with the tiller positioned to the side when maneuvering in confined spaces.

[0011] According to a preferred embodiment of the invention, the maximum speed in the second swivel range corresponds to 0.2 to 0.4 times the maximum travel speed in the first swivel range, and in particular to 0.33 times the maximum travel speed in the first swivel range. Such a limitation of the maximum travel speed can improve the cornering behavior of pedestrian-operated, tiller-guided industrial trucks, resulting in high operational safety, as well as improving handling and ergonomics for the operator at large steering angles.

[0012] According to the invention, the maximum travel speed in the transition range can be varied linearly with the pivot angle of the tiller. By linearly reducing or increasing the maximum travel speed with increasing pivot angle of the tiller in the transition range, the driving characteristics and cornering stability of a pedestrian-operated industrial truck can be easily improved, while maintaining favorable handling and ergonomics for the operator. The continuous change in the maximum travel speed can be stepless or in fine increments.

[0013] According to the invention, the first swivel range comprises a swivel angle of the drawbar in the range of + / - 50°. 0 up to + / - 70 0 , especially + / -60 0Starting from the straight-ahead position of the tiller, the variable control of the maximum speed is therefore limited to high swivel angles and thus large steering angles of the tiller. At these angles, especially with a loaded forklift, a reduction in travel speed is advisable for stability reasons. Furthermore, due to the high swivel angle and the resulting lateral position of the tiller, the distance between the operator and the forklift decreases in the case of a tiller-guided forklift. Therefore, reducing the travel speed can improve operational safety and handling of the forklift by the operator, who is positioned close to the forklift at high swivel angles.

[0014] The variable control of the maximum speed can be achieved adjacent to the first swivel angle up to the maximum swivel position and thus the maximum steering angle of the drawbar.

[0015] If, according to the invention, the second pivoting range comprises a pivoting angle of the tiller in the range of 0° to 15° before the maximum pivoting position of the tiller, in particular 10° before the maximum pivoting position, a constant reduced maximum speed of the industrial truck can be easily achieved in the range of the second pivoting angle of the tiller, which results in improved stability and handling of the pedestrian-operated industrial truck, especially when maneuvering in confined spaces, with high operational safety for the operator, at high steering angles in the range of the maximum steering angle.

[0016] According to a preferred embodiment of the invention, a continuous sensor device, in particular a potentiometer, is provided to detect the swivel angle of the drawbar. With such a potentiometer, the swivel angle and thus the steering angle of the drawbar can be easily detected, and therefore variable control of the maximum speed can be carried out in the transition range between the first and second swivel ranges of the drawbar.

[0017] If, according to a preferred embodiment of the invention, an electronic control device is provided which is operatively connected to the sensor device on the input side and to the drive motor on the output side, the maximum driving speed and thus the maximum speed can be easily controlled by appropriate control of the drive motor as a function of the swivel angle and thus the steering angle of the drawbar.

[0018] Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiment shown in the schematic figures. These figures show... Fig. 1 a forklift truck according to the invention in a side view and Fig. 2 the industrial truck of Fig. 1. in a top view.

[0019] In the Fig. Figure 1 shows a pedestrian-operated pallet truck, a tiller-guided industrial truck 1, with a drive unit 2 and a load unit 3 that can be raised and lowered relative to the drive unit 2. The load unit 3 comprises a load fork formed by, for example, two laterally spaced load arms 4. The load unit 3 is supported on a roadway by means of load rollers 5 arranged at the tips of the load arms 4.

[0020] In the drive unit 2, a drive unit (not shown) comprising a drive wheel 6 and an electric drive motor driving the drive wheel 6 is arranged to pivot about a vertical pivot axis 7. The operator steers the industrial truck 1 by means of a tiller 8 connected to the drive unit, which is also arranged to pivot about the vertical pivot axis 7.

[0021] The tiller 8 can be directly connected to the drive unit and thus to the drive wheel 6. However, it is also possible to provide an electric steering motor for steering the drive unit; this motor is operatively connected to the drive unit and is controlled about the vertical pivot axis 7 depending on the pivot position of the tiller 8. In such industrial trucks with electric steering, the pivot axis 7 of the drive unit can be spaced laterally from the pivot axis of the tiller 8.

[0022] The tiller 8 is rotatably mounted on the industrial truck 1 about a horizontal pivot axis 9, so that it can be pivoted downwards from the substantially vertical position shown to a substantially horizontal position. The pivot range of the tiller 8 about the horizontal pivot axis 9 is divided into an upper braking range in the area of ​​the vertical position, a normal driving range adjoining this downwards, and a lower braking range adjoining the normal driving range in the area of ​​the horizontal position of the tiller 8.

[0023] The drawbar 8 is here - as seen from the Fig. 2 is evident - starting from a straight-ahead driving position with a swivel angle α=0 0 the drawbar 8 and thus a steering angle of 0 0 in both directions to a maximum swivel position with a maximum swivel angle α=+ / -90 0The drawbar 8 can be swivelled and thus to the maximum steering angle.

[0024] According to the invention, a first swivel range S1 encompassing the straight-ahead driving position of the tiller 8 is provided, in which the industrial truck travels at a maximum speed V max , for example 6 km / h, is operable and a second swivel range S2 is provided for each steering direction, which is arranged in the area of ​​the maximum swivel positions of the drawbar 8 and each has a maximum swivel angle α=+ / -90 0 The drawbar 8 includes a mechanism in which the industrial truck 1 can be operated at a reduced maximum speed V1. The reduced maximum speed V1 preferably corresponds to 0.33 times the maximum travel speed V. max , so that at a maximum driving speed of V max = 6 km / h results in a reduced maximum speed at maximum swivel angle and thus a steering angle of the drawbar of V1 = 2 km / h.

[0025] Between the first pivoting area S1 of the drawbar 8 and the second pivoting area S2 of the drawbar 8, a transition area S3 is formed in which the maximum driving speed V max The pivot angle α of the drawbar 8 is continuously variable and therefore controllable. According to the Fig. In the speed diagram shown in Figure 2, in which the driving speed V is shown as a function of the swivel angle α and thus the steering angle of the drawbar 8, a linear progression of the maximum driving speed is provided in the transition range S3, so that when the drawbar 8 is swiveled from the straight-ahead position and thus the first swivel range S1 towards the maximum swivel position and thus the second swivel range S2, the driving speed in the transition range S3 is different from the maximum driving speed V. maxThe reduced maximum speed V1 is linearly reduced, and accordingly, when the drawbar 8 pivots back from the maximum pivot position and thus the second pivot range S2 of the drawbar 8 in the direction of the straight-ahead driving position and thus the first pivot range S1, the driving speed V in the transition range S3 from the maximum maximum speed V1 to the maximum driving speed V max It increases linearly.

[0026] The first pivot range S1 of the drawbar 8 extends from the straight-ahead driving position with a pivot angle of the drawbar 8 of α=0 0 via a pivot angle α and thus steering angle of the drawbar 8 of in particular α = + / - 60°. The second pivot range S2 of the drawbar 8 comprises a pivot angle range of in particular approximately 7°. 0 before the respective maximum swivel position with maximum swivel angle α=+ / - 90 0and thus maximum steering angle and thus a swivel angle α of the drawbar 8 from α=+ / - 83° to α=+ / - 90 0 The transition area S3, located between the first swivel range S1 and the second swivel range S2, in which the maximum travel speed V max The pivot angle α of the drawbar 8 is reduced or increased linearly, thus encompassing a pivot angle range of approximately 23°. 0 and encompasses the steering range of the drawbar 8 of a swivel angle and thus steering angle α=+ / -60 0 up to α=+- / 83 0 the drawbar 8.

[0027] The inventive control of the travel speed V in the transition range S3, which is dependent on the swivel angle and thus the steering angle, takes place in particular in the normal driving range of the drawbar 8 pivoted about the horizontal swivel axis 9 and / or when the industrial truck 1 is loaded.

[0028] With the inventive control of the travel speed V in the pivot angle and thus steering angle dependent transition range S3, increased operational safety and improved operating behavior for the operator result from the avoidance of abrupt changes in travel speed, particularly when maneuvering a loaded industrial truck in confined spaces, where the operator stands to the side of the industrial truck 1 when the tiller 8 is pivoted, resulting in a small distance and thus a close proximity of the operator to the industrial truck 1.

Claims

[1] Tiller-steered industrial truck (1) with a tiller (8) pivotable about a vertical axis (7) and a drive motor, wherein the maximum travel speed (V) max ) of the industrial truck (1) is controllable depending on the swivel angle (α) of the tiller (8) about the vertical axis (7), wherein in a first swivel range (S1) about the straight-ahead position of the tiller (8) the industrial truck (1) travels at a maximum speed (V max ) is operable and is operable in a second swivel range (S2), which includes the maximum swivel position of the drawbar (8), with a reduced maximum speed (V1), characterized by , that a transition zone (S3) is formed between the first swivel zone (S1) and the second swivel zone (S2), in which the maximum travel speed (V) max) can be continuously varied with the pivot angle (α) of the drawbar (8), whereby in the transition range (S3) the maximum driving speed (V) max ) is linearly variable with the swivel angle (α) of the drawbar (8), wherein the first swivel range (S1) has a swivel angle (α) of the drawbar (8) in the range of + / - 50 0 up to + / - 70 0 , especially + / - 60 0 , starting from the straight-ahead position of the drawbar (8) and the second pivot range (S2) encompasses a pivot angle (a) of the drawbar (8) in the range of 0 0 up to 15 0 before the maximum pivot position of the drawbar (8) includes, in particular 10 0 before the maximum pivot position of the drawbar (8). [2] Tiller-steered industrial truck (1) according to claim 1, characterized by , that the maximum speed (V1) in the second swivel range (S2) corresponds to the range of 0.2 to 0.4 times the maximum driving speed (V) max) in the first swivel range (S1) corresponds, in particular, to 0.33 times the maximum travel speed (V) max ) in the first swivel range (S1) corresponds to... [3] Tiller-steered industrial truck (1) according to claim 1 or 2, characterized by , that the swivel angle (α) of the drawbar (8) can be detected by means of a continuous sensor device, in particular a potentiometer. [4] Tiller-steered industrial truck (1) according to claim 3; characterized by , that an electronic control unit is provided which is in operative communication on the input side with the sensor device and on the output side with the drive motor.

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