AU2014214196B2

AU2014214196B2 - Steering system for a vehicle, and multidirectional transport vehicle

Info

Publication number: AU2014214196B2
Application number: AU2014214196A
Authority: AU
Inventors: Achim OTTERBEIN
Original assignee: Hubtex Maschinenbau GmbH and Co KG
Current assignee: Hubtex Maschinenbau GmbH and Co KG
Priority date: 2013-02-05
Filing date: 2014-01-29
Publication date: 2017-01-12
Anticipated expiration: 2034-01-29
Also published as: EP2953837A1; DE102013101115A1; CN104995084A; CN104995084B; WO2014122054A1; EP2953837B1; AU2014214196A1; PL2953837T3

Abstract

The invention relates to a steering system for a vehicle comprising at least three steerable wheels (9, 12). A selectively activatable operating element (22) is provided, the activation of which triggers one of the following functions: - an actuation of the steering target value generator (19) leads to a rotation of the steering polar axis (A) about a center of rotation (Q) of the steering polar axis; - the steering polar axis (A) is rotated about the center of rotation (Q) in a specified rotational direction for the duration of the activation; - the steering polar axis (A) is rotated about the center of rotation (Q) in a specified rotational direction by a specified angle; or - the steering polar axis (A) is rotated about the center of rotation (Q) in a specified rotational direction into a specified angular position.

Description

1 2014214196 09 Nov 2016

Steering system for a vehicle, and multidirectional transport vehicle

The present invention relates to a steering system for a vehicle having at least three steerable wheels and a steering set point value controller steering the wheels by a steering program, and a steering pole, upon which the wheels are oriented during cornering, is displaced by actuating the steering set point value 5 controller along a steering pole axis. The present invention also includes a multidirectional transport vehicle having such a steering system. A multidirectional transport vehicle having such a steering system is, for example, known from publication WO 01/70556 A1. In this vehicle, this steering program, 10 also referred to as "all-wheel steering," may be switched to a second steering program for simultaneously rotating the steering pole axis of all wheels in the same direction by actuating the steering set point value controller, also referred to as "diagonal steering." When actuating the steering set point value controller, the steered wheels during all-wheel steering are actuated in such a manner that its 15 rotary axes always intersect the steering pole. On the contrary, during diagonal steering, the wheels are steered as a function of actuating the steering set point value controller in such a manner that the rotary axes of the wheels run parallel, in other words, that the steering pole lies at infinity. When actuating the steering set point value controller when diagonal steering is selected, the vehicle carries out a 20 change in direction without, however, changing its orientation in this instance, whereas, when all-wheel steering is selected, the orientation of the vehicle follows the change in driving direction.

In order to be able to, if necessary, change the orientation of the vehicle relative to 25 its direction of driving independent of the currently selected steering program, a further control device, which, if necessary, may be simultaneously actuated by the steering steering set point value controller, is provided in this vehicle. Actuating this second control device results in a correction of the steering angle of the wheels of at least one axis in a manner not corresponding with the selected 30 steering program, and that is approximately proportionate to the deflection of this control device, which is designed as a joystick. 2 2014214196 09 Nov 2016

Another steering system for a multidirectional transport vehicle is known from publication EP 1 657 140 A2. In this steering system, in addition to the steering set point value controller, which always operates according to the steering program "all-wheel steering," two further operating elements are provided: a first operating 5 element for continuously displacing the steering line and a second operating element for continuously controlling the main direction of the vehicle. By this measure, an intuitive steering is to be created that completely foregoes permanently defined steering programs so as to achieve a higher flexibility of the steering system. 10 A disadvantage of the previously quoted related art is that, owing to the requirements for driving operation, at least two operating elements working proportionately (in the case of the WO 01/70556 A1, the steering set point value controller and the control device; in the case of the EP 1 657 140 A2, the steering 15 set point value controller and two additional operating elements) provide a plurality of degrees of freedom in input to the driver, and steering such a vehicle requires considerable practice and also considerable concentration in the daily operation, where undesired, at times difficult to handle driving situations are to be avoided. 20 EP 2 253 528 A2 discloses a method to change a steering program dynamically. The driver can switch between a longitudinal driving program and a transverse driving program and effect rotation of the steering line in a new direction. 25 Hence, the object of the present invention is to create a steering system that ensures sufficient flexibility in steering a multidirectional transport vehicle which, however, is easier to operate for a driver.

This object is achieved by the steering system represented in Claim 1. 30

This steering system, which—as mentioned at the outset—includes at least the steering program "all-wheel steering," is, according to the present invention, 3 provided with a selectively activatable operating element, which activation triggers one of the following functions: - Actuating the steering set point value controller results in a rotation of the steering pole axis about a rotary pole of a steering pole axis. Based on the steering state of the vehicle at the moment of activating the operating element, an actuation of the only steering set point value controller results, as intended by the steering program "diagonal steering," in influencing the steering angle of the steered wheels. For the duration of activating the operating element, the distance of the steering pole from the rotary pole of a steering pole axis does not change when actuating the only steering set point value controller. After completing the activation of the operating element, the steering pole axis remains in the achieved angular position. A renewed actuation of the steering set point value controller results in a displacement of the steering pole on this steering pole axis. - The steering pole axis, when activating the operating element, is rotated in a specified direction of rotation about the rotary pole of a steering pole axis by a specified angle. Preferably, the rotation is carried out at a constant angular velocity. In turn, actuating the steering set point value controller results in a displacement along the steering pole axis in its respective current angle position. Preferably, the selectively activatable operating element is, in turn, again embodied in such a manner that the rotation about the rotary pole of a steering pole axis occurs in either one or the other direction of rotation. Alternatively, two different, selectively activatable operating elements are in turn provided, wherein one affects the rotation in one sense of rotation, and the other affects the rotation in the other sense of rotation.

The present invention is already realized by a steering system including a single selectively activatable operating element, which activation triggers only one of the functions mentioned previously. In particular, the present invention relates, however, to a steering system, in which the selectively activatable operating element is capable of being switched to a plurality, in particular, to all of the 4 2014214196 09 Nov 2016 previously described functions, or in which a plurality of separate operating elements are provided, which are assigned respectively to the activation of one of the functions previously described, and, in particular, one operating element is provided for each of the previously described functions. 5

In addition, activation of the selectively activatable operating element may trigger one or more of the following functions: - The steering pole axis is rotated in a specified rotary direction about the rotary 10 pole of a steering pole axis for the duration of the activation, preferably at a constant angular velocity. The simultaneous actuation of the steering set point value controller then results in a displacement of the steering pole on this steering pole axis. After completing the deactivation of the operating element, the steering pole axis remains in the assumed angular position. Preferably, the 15 selectively activatable operating element is designed in such a manner that the steering pole axis may be selectively rotated in one or the other direction of rotation. Alternatively, two operating elements are provided, one for rotating the steering pole axis in one direction of rotation, and the other for rotating the steering pole axis in the other direction of rotation. 20 - The steering pole axis, when activating the operating element, is rotated in a specified direction of rotation about the rotary pole of a steering pole axis into a specified angle position. The rotary velocity about the rotary pole of a steering 25 pole axis is, in turn, preferably constant. Thus, by actuating the selectively activatable operating element, a specific steering state is generated independent of the initial situation in which the vehicle is at the moment of activating the operating element. In turn, the operating element is preferably designed in such a manner that the direction of rotation, in which the steering 30 pole axis about the rotary pole of a steering pole axis is rotated, is specifiable. Alternatively, two separate operating elements are provided, and activating one operating element results in a clockwise rotation, and activating the other results in a counterclockwise rotation. Preferably, means are also provided, by 5 which the specified angular position in which the steering pole axis is rotated when activating the operating element may be pre-selected. A selectively activatable operating element is preferably designed as an on/off switching element for activating/deactivating one of the provided functions. Preferably, a separate on/off switching element exists for each of the provided functions. Alternatively, it is possible to provide means by which one or a plurality of on/off switching elements may be assigned to different functions.

The on/off switching element is preferably designed to be self-resetting to its off-position. A manual resetting for terminating the execution of the activated function or renewed activation of the function is, thus, not necessary.

The switching element may particularly be a push-button, pull, tilt, rocker and/or rotary element. Thus, switching elements that, for example, are rotable or tactile, may also be used, for example, for specifying by rotation the direction of rotation, in which the steering pole axis about the rotary pole of a steering pole axis occurs when activating the respective function, which is carried out by actuating a push button of the same element.

The steering set point value controller may be designed in any manner that enables a displacement of the steering pole on the steering pole axis as a function of the deflection of the steering set point value controller from its center position. Preferably, the steering set point value controller includes a joy stick for this purpose, particularly preferable is a steering wheel.

The present invention also includes a multidirectional transport vehicle having a steering system according to the present invention, in particular, a multidirectional forklift.

Further possible embodiments of the present invention are described in an exemplary manner in reference to the appended drawings. 6

Figure 1 shows —schematically—a multidirectional transport vehicle using the example of a multidirectional forklift in a plan view;

Figure 2 shows a schematic diagram of a steering system according to the present invention featuring a control system of such a multidirectional transport vehicle; and

Figures 3a through 9c show a schematic illustration of different steering situations, on the basis of which different steering possibilities of the steering system according to the present invention are to be described.

In Figure 1, the multidirectional transport vehicle referenced in its entirety by 100 includes a chassis 1, which in plan view is approximately U-shaped. On cross beam 2 of the U, it carries an upright mast 3, at which a fork assembly 4 is situated that may be raised and lowered. The fork assembly is designed in such a manner that its tines 5, 6 may be displaced between a remote, in Figure 1, solid position and a neighboring position illustrated as a dashed line in Figure 1, so as to adapt its distance respectively to the goods to be transported.

Furthermore, a housing 7, which accommodates a plurality of units and devices for operating multidirectional transport vehicle 100 and a battery assembly 13, is situated on cross beam 2 of the U.

According to Figure 1, on the bottom and top at cross beam 2—the latter being obscured by an illustration of a control stand 8—a wheel 9 is respectively indicated, which is actuated by a motor not illustrated in the drawing. At segments 10, 11 of chassis 1 extending, according to Figure 1, from cross beam 2 to the right, wheels 12 are respectively provided in the end sections. All wheels 9, 12 are rotatable about wheel axes P and are respectively situated in a steerable manner about a steering axis X running perpendicular to the drawing plane.

Control stand 8, illustrated in Figure 1 at the upper end of cross beam 2, includes the operating elements to be actuated by an operator for operating multidirectional 7 2014214196 09 Nov 2016 forklift 100, including a steering wheel 14 and a push button assembly 15 having a plurality of push buttons, which function is described further below.

Furthermore, the control stand includes a device not illustrated in detail—for 5 example, a "gas pedal"—that specifies the set point value for the drive power of the drive engines not illustrated in the drawing, which is provided by control units 16,17.

As illustrated in Figure 2, steering wheel 14 is connected to a steering set point 10 value controller 19, which converts the position of steering wheel 14 into correlated electrical signals. The latter are fed via electrical line 20 to central control system 18. This control system 18 converts the data received from steering set point value controller 19 into signals, which are fed via lines 23, 24, 25, 26 to hydraulic valves 27, 28, 29, 30 for the purpose of actuating steering devices 31, 32, 33, 34 of the 15 wheels of the multidirectional transport vehicle.

Each of steering devices 31, 32, 33, 34 includes a hydraulic motor, which is connected via two hydraulic lines 35, 35', 36, 36', 37, 37', 38, 38' to hydraulic valves 27, 28, 29, 30 and, depending on the set point steering angle specified by 20 the control system, is charged by hydraulic fluid.

Each of steering devices 31, 32, 33, 34 otherwise designed in a conventional manner includes steering angle sensors 39, 40, 41, 42, via which electrical lines 43, 44, 45, 46 provide control command 18 with an electrical signal correlating with 25 the respective actual steering angle, so that steering devices 31, 32, 33, 34 are controlled more strictly.

In the illustrated exemplary embodiments, the individual push buttons 21 of push button assembly 15 respectively form a selectively activatable operating element 30 22, which activation triggers one of the following functions schematically illustrated on the basis of Figures 3a through 9c. For this purpose, push button assembly 15 is connected via a transmission line 48 to control system 18. 8

Figure 3a illustrates the initial steering situation of the exemplary embodiment of the multidirectional transport vehicle here illustrated. Steering wheel 14 is in its neutral position. None of the selectively activatable operating elements 22 is activated. Wheel axes P are running parallel to each other or are congruent. In the exemplary embodiment here illustrated, the control system is in this initial situation in the steering program "all-wheel steering." If steering wheel 14 is now turned in the counterclockwise direction, that is, turned to the left, the steered wheels are steered in such a manner that wheel axes P intersect joint steering pole O on steering pole axis A. When actuating steering wheel 14, steering pole O is displaced on a steering pole axis A, and that is, when actuating the steering wheel in a rotary manner in the counterclockwise direction to the left and, when actuating the steering wheel in a rotary manner in the clockwise direction, accordingly to the right.

On the basis of Figure 4a and b, the functionality that results in the illustrated exemplary embodiment of the steering system according to the present invention is now to be described, when push button 21, in the drawing on the left, of push button assembly 15 is pressed and operating element 22, for this reason, is transferred into its activated state.

When pressing the left push button of push button assembly 15, control system 18 is influenced in such a manner that a rotary actuation of steering wheel 14 results in a rotation of steering pole axis A in the same direction of rotation. Figure 4a illustrates the circumstances when the operating element is activated in the straight-ahead position of the wheels illustrated in Figure 3a and steering wheel 14 is, after activating this operating element, turned in the counterclockwise direction, that is, to the left. Steering pole axis A is rotated in the same direction of rotation about a rotary pole of a steering pole axis Q; wheel axes P continue to run parallel to each other, so that the multidirectional transport vehicle transitions to a diagonal drive without changing its orientation. If the steering wheel is rotated clockwise, that is, rotated to the right, steering pole axis A about a rotary pole of a steering pole axis Q thus respectively also rotates in the clockwise direction. 9 2014214196 09 Nov 2016

Figure 4b illustrates a situation in which the left push button of push button assembly 15 has been pressed and in which the multidirectional transport vehicle was cornering as illustrated in Figure 3b. From this initial situation, shown as a dashed line in Figure 4b, steering pole axis A is again rotated in the 5 counterclockwise direction and steering pole O is displaced to a circular arc K. As long as operating element 22 is activated, that means, as long as the left push button of push button assembly remains pressed, a rotary actuation of steering wheel 14 merely results in a rotation of steering pole axis A about a rotary pole of a steering pole axis Q, it does not result, however, in displacing steering pole O 10 along steering pole axis A. After releasing the push button and, for this reason, deactivating this operating element, the angular position of steering pole axis A, however, remains constant and a rotary actuation of steering wheel 14 results in displacing the steering pole along this steering pole axis. 15 In the exemplary embodiment illustrated in Figures 5a) and 5b), the steering system according to the present invention includes a push button assembly 15 having two push buttons 21, which form respectively one selectively activatable operating element 22. When actuating one of push buttons 21, the function results in that steering pole axis A is rotated about a rotary pole of a steering pole axis Q 20 in the rotary direction specified by the respective push button for the duration of the activation. Figure 5a shows the situation on the basis of driving straight ahead illustrated in Figure 3a; Figure 5b shows the situation based on cornering illustrated in Figure 3b. A simultaneous actuation of the steering wheel not shown in Figures 5a and 5b might result, based on the steering situation illustrated in 25 Figure 5a, in the wheels in the corresponding direction of rotation being steered in such a manner that its wheel axes P intersect a steering pole located on the steering pole axis. Based on the steering situation according to Figure 5b, a rotary actuation of the steering wheel would result in that steering pole O is displaced on steering pole axis A. Such a displacement is possible both during the rotation of 30 the steering pole axis about the rotary pole of a steering pole axis, meaning, during the activation of respective operating element 22, and also after deactivating said operating element 22, which means, when the angular position of the steering pole axis about the rotary pole of a steering pole axis no longer changes. ίο 2014214196 09 Nov 2016

An exemplary embodiment having another functionality of selectively activatable operating elements 22 is illustrated in Figures 6a) through 7b). Activating these operating elements results in that steering pole axis A is rotated in a specified 5 direction of rotation about a rotary pole of a steering pole axis Q by a specified angle. Figure 6a) represents the steering situation after actuating a rotation of 45° based on driving straight ahead, illustrated in Figure 3a). Figure 6b) shows the steering situation after actuating said operating element 22, which results in a rotation of steering pole axis A about a rotary pole of a steering pole axis Q of 90° 10 in a counterclockwise direction.

Figure 7a) shows the steering situation when 45°-operating element 22 is actuated, as shown in Figure 6a), when cornering, in which steering pole O is in position I. Steering pole axis A is rotated about a rotary pole of a steering pole axis 15 Q by 45°, and steering pole O is displaced into position II. Figure 7b) shows the steering situation in the same initial situation when the 90°-operating element is actuated. As is the case of the functionality described on the basis of Figures 5a and 5b, a simultaneous rotary actuation of the steering wheel not illustrated in Figures 6a through 7b results in that the wheels, based on the steering situation 20 illustrated in Figures 6a) and 6b), are steered in such a manner that wheel axes P intersect a steering pole located on the steering pole axis and, in the steering situations illustrated in Figures 7a) and 7b), in that steering pole O is displaced along current steering pole axis A. 25 The bottom row of the operating elements in Figures 6a) through 7b) serves the rotation of steering pole axis A about a rotary pole of a steering pole axis Q by the same angular value as the respective overlying operating element 22, however, in a reversed direction of rotation. 30 A further exemplary embodiment having another functionality of selectively activatable operating elements 22 is illustrated in Figures 8a) through c), 9a through c). By actuating respective selectively activatable operating elements 22, the steering pole axis is displaced from an arbitrary initial position to the respective 2014214196 09 Nov 2016 11 angular position specified on the operating element and that is without displacing the position of steering pole 0 on steering pole axis A. In Figures 8a) through c) longitudinal, transverse, and 45° oblique travel is symbolized, which means, the end positions of the wheels when the activation of corresponding operating 5 element 22 is carried out in a straight-ahead position of the steering wheel not illustrated in these figures. Figures 9a) through c) illustrate the steering situations, when the respective operating elements illustrated in bold in the drawing are actuated, when the vehicle is cornering, symbolized in Figure 9a. In this instance, the initial positions, in which the steering pole is located before activating the 10 operating element, are referenced by I, the end positions after activating the operating element are referenced by II. 12 2014214196 09 Nov 2016

List of Reference Characters: 100 Multidirectional transport vehicle 1 Chassis 2 Cross beam 3 Mast 4 Fork assembly 5 Tines 6 Tines 7 Housing 8 Control Stand 9 Wheels 10 Segment 11 Segment 12 Wheels 13 Battery assembly 14 Steering wheel 15 Push button assembly 16 Control unit 17 Control unit 18 Central control system 19 Steering set point value controller 20 Line 21 Push buttons 22 Operating element 23 Line 24 Line 25 Line 26 Line 27 Hydraulic valve 28 Hydraulic valve 2014214196 09 Nov 2016 13 29 Hydraulic valve 30 Hydraulic valve 31 Steering device 32 Steering device 33 Steering device 35, 35’ Hydraulic line 36, 36’ Hydraulic line 37, 37' Hydraulic line 38, 38' Hydraulic line 39 Steering angle sensor 40 Steering angle sensor 41 Steering angle sensor 42 Steering angle sensor 43 Line 44 Line 45 Line 46 Line 48 Line A Steering pole axis K Circular arc 0 Steering Pole P Wheel axis Q Rotary pole of a steering pole axis X Steering axes

Claims

Claims:

1. A steering system for a vehicle having at least three steerable wheels and a steering set point value controller steering the wheels by a steering program, wherein a steering pole, on which the axes of the wheels are oriented during cornering, is displaced by actuating the steering set point value controller along a steering pole axis, wherein a selectively activatable operating element is provided, which activation triggers one of the following functions: - Actuating the steering set point value controller results in a rotation of the steering pole axis about a rotary pole of a steering pole axis; - The steering pole axis is rotated in a specified rotary direction about the rotary pole of a steering pole axis by a specified angle based on an arbitrary initial angle.
2. The steering system according to Claim 1, wherein the selectively activatable operating element has an on/off switching element for activating/deactivating one of the provided functions.
3. The steering system according to Claim 2, wherein the switching element is designed to be self-resetting to the off-position.
4. The steering system according to Claim 2 or 3, wherein the switching element comprises a push-button, pull, tilt, rocker and/or rotary element.
5. The steering system according to one of Claims 1 through 4, wherein the steering set point value controller comprises a steering wheel.
6. A multidirectional transport vehicle, wherein it comprises a steering system according to one of Claims 1 through 5.