STEERING AXLE FOR A STEERABLE VEHICLE AND INDUSTRIAL TRUCK

Abstract

A steering axle (20) for a steerable vehicle includes an axle housing (1), a first steering knuckle (4), a second steering knuckle (5), a steering motor (6), and a steering gear (16). The first steering knuckle (4) and the second steering knuckle (5) are mounted so as to be steerable in the axle housing (1). The steering axle (20) has a first flexible drive (21) that connects a first output (12) of the steering gear (16) to the first steering knuckle (4) in terms of drive, and a second flexible drive (22) that connects a second output (13) of the steering gear (16) to the second steering knuckle (5) in terms of drive, so that a rotational speed of the steering motor (6) results in a steering movement of the first steering knuckle (4) and of the second steering knuckle (5). Also disclosed is a corresponding industrial truck.

Claims

1. A steering axle (20) for a steerable vehicle, comprising: an axle housing (1); a first steering knuckle (4); a second steering knuckle (5); a steering motor (6); a steering gear (16) having a first output and a second output, wherein the first steering knuckle (4) and the second steering knuckle (5) are mounted so as to be steerable in the axle housing (1); and a first flexible drive (21) and a second flexible drive (22), wherein the first flexible drive (21) connects the first output (12) of the steering gear (16) to the first steering knuckle (4) in terms of drive, and wherein the second flexible drive (22) connects the second output (13) of the steering gear (16) to the second steering knuckle (5) in terms of drive, so that a rotational speed of the steering motor (6) results in a steering movement of the first steering knuckle (4) and of the second steering knuckle (5).

2. The steering axle (20) as claimed in claim 1, wherein the first output (12) is configured as a first drive pulley (12) of the first flexible drive (21) and the second output (13) is configured as a second drive pulley (3) of the second flexible drive (22), wherein the first steering knuckle (4) has a first output pulley (14) of the first flexible drive (21), which is connected to the first steering knuckle (4) for conjoint rotation, and wherein the second steering knuckle (5) has a second output pulley (17) of the second flexible drive (22), which is connected to the second steering knuckle (5) for conjoint rotation.

3. The steering axle (20) as claimed in claim 1, wherein at least one of the first drive pulley (12), the second drive pulley (13), the first output pulley (14) or the second output pulley (17) have a running surface which deviates from a circular shape; wherein the running surface which deviates from the circular shape is configured so that the first steering knuckle (4) is aligned at an Ackerman angle with respect to the second steering knuckle (5) at each steering angle that can be set and/or wherein at least one of the first drive pulley (12), the second drive pulley (13), the first output pulley (14) or the second output pulley (17) are mounted eccentrically in such a way that the first steering knuckle (4) is aligned at an Ackerman angle with respect to the second steering knuckle (5) at each steering angle that can be set.

4. The steering axle (20) as claimed in claim 3, wherein the first drive pulley (12) and the second drive pulley (13) each has an elliptical running surface or a rectangular running surface with rounded edges.

5. The steering axle (20) as claimed in claim 4, wherein the first drive pulley (12) has a fixed rotational offset with respect to the second drive pulley (13).

6. The steering axle (20) as claimed in claim 5, wherein the first output pulley (14) and the second output pulley (17) each has an elliptical running surface or a rectangular running surface with rounded edges.

7. The steering axle (20) as claimed in claim 1, wherein the first flexible drive (21) and the second flexible drive (22) are designed as belt drives or as chain drives.

8. The steering axle (20) as claimed in claim 1, wherein the steering gear (16) is configured as an at least two-stage planetary gear (16).

9. The steering axle (20) as claimed in claim 8, wherein the first flexible drive (21) and the second flexible drive (22) are components of the steering gear (16), in that a running surface of the first drive pulley (12) and a running surface of the second drive pulley (13) are smaller than a running surface of the first output pulley (14) and a running surface of the second output pulley (17).

10. The steering axle (20) as claimed in claim 9, wherein the first output (12) and the second output (13) are connected for conjoint rotation to a ring gear (120) or a planet carrier (119) of the steering gear (16).

11. The steering axle (20) as claimed in claim 1, wherein the steering axle (20) is configured to monitor set steering angles for each individual wheel of the steerable vehicle.

12. The steering axle (20) as claimed in claim 1, wherein a first adjusting unit is provided, the first adjusting unit configured to automatically adjust a tension of the first flexible drive (21), and wherein a second adjusting unit is provided, the second adjusting unit configured to automatically adjust a tension of the second flexible drive (22).

13. The steering axle (20) as claimed in claim 1, wherein the steering motor (6) is configured as an electric motor (6).

14. The steering axle (20) as claimed in claim 1, wherein the steering axle (20) is configured as a portal axle (20).

15. The steering axle (20) as claimed in claim 1, wherein the steering motor (6) is arranged in the axle housing (1) or below the axle housing (1).

16. An industrial truck, comprising a steering axle (20) as claimed in claim 1.

17. A steering axle (20) for a steerable vehicle, comprising: an axle housing (1); a first steering knuckle (4); a second steering knuckle (5); a steering motor (6); a steering gear (16) having a first output and a second output, wherein the first steering knuckle (4) and the second steering knuckle (5) are mounted so as to be steerable in the axle housing (1); and a first flexible drive (21) and a second flexible drive (22), wherein the first flexible drive (21) connects the first output (12) of the steering gear (16) to the first steering knuckle (4) in terms of drive, and wherein the second flexible drive (22) connects the second output (13) of the steering gear (16) to the second steering knuckle (5) in terms of drive, so that a rotational speed of the steering motor (6) results in a steering movement of the first steering knuckle (4) and of the second steering knuckle (5); wherein the first drive pulley (12) and the second drive pulley (13) each has an elliptical running surface or a rectangular running surface with rounded edges, and wherein the first flexible drive (21) and the second flexible drive (22) are designed as belt drives or as chain drives.

18. The steering axle (20) as claimed in claim 17, further comprising: a first adjusting unit configured to automatically adjust a tension of the first flexible drive (21); and a second adjusting unit configured to automatically adjust a tension of the second flexible drive (22).

19. The steering axle (20) as claimed in claim 18, wherein the steering motor (6) is configured as an electric motor (6) and wherein the steering axle (20) is configured as a portal axle (20).

20. The steering axle (20) as claimed in claim 19, wherein the steering motor (6) is arranged in the axle housing (1) or below the axle housing (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention is explained by way of example below with reference to exemplary embodiments illustrated in the figures.

[0043] More specifically:

[0044] FIG. 1 shows, by way of example, one possible embodiment of a steering axle according to the invention for a steerable vehicle, according to the example for an industrial truck (not illustrated in FIG. 1), in a perspective view,

[0045] FIG. 2 shows the steering axle according to FIG. 1 in a view from above,

[0046] FIG. 3 shows schematically and in part the steering motor and the steering gear on the axle housing in a common housing, and

[0047] FIG. 4 shows schematically another possible embodiment of a steering axle according to the invention for a steerable vehicle in cross section.

[0048] Identical objects, functional units and comparable components are denoted by the same reference signs throughout the figures. These objects, functional units and comparable components are of identical design in respect of their technical features, unless explicitly or implicitly implied otherwise by the description.

DETAILED DESCRIPTION

[0049] FIG. 1 shows, by way of example, one possible embodiment of a steering axle 20 according to the invention for a steerable vehicle (not illustrated in FIG. 1), according to the example for an industrial truck, in a perspective view. According to the example, the steering axle 20 is designed as a portal axle 20 and comprises an axle housing 1, a steering motor 6, a steering gear 16, a first steering knuckle 4 and a second steering knuckle 5. The first steering knuckle 4 and the second steering knuckle are each mounted so as to be steerable in the axle housing 1. A first steerable wheel 2 is arranged on the first steering knuckle 4 and a second steerable wheel 3 is arranged on the second steering knuckle 5. According to the example, the steering motor 6 and the steering gear 16 are arranged in a common housing 9 on the axle housing 1. The part of the common housing 9 which has the steering gear 16 is rotatably mounted with respect to the part of the common housing 9 which has the steering motor 6. The part of the common housing 9 which has the steering motor 6 cannot rotate relative to the axle housing 1.

[0050] According to the example, the steering motor 6 is designed as an electric motor 6 and the steering gear 16 is designed as a two-stage planetary gear 16, in which a ring gear common to both planetary stages forms the output.

[0051] The steering axle 20 further comprises a first flexible drive 21 and a second flexible drive 22, wherein the first flexible drive 21 connects a first output 12 of the steering gear 16 to the first steering knuckle 4 in terms of drive, and wherein the second flexible drive 22 connects a second output 13 of the steering gear 16 to the second steering knuckle 5 in terms of drive, so that a rotational speed of the steering motor 6 results in a steering movement of the first steering knuckle 4 and of the second steering knuckle 5.

[0052] According to the example, the first flexible drive 21 is embodied as a chain drive 21 and comprises a first drive pulley 12, which is identical with the first output 12. In addition, the first flexible drive 21 comprises a first output pulley 14 and a first chain 15. According to the example, the first output 12 or first drive pulley 12 is connected for conjoint rotation to the ring gear of the planetary gear 16, and the first output pulley 14 is connected for conjoint rotation to the first steering knuckle 4.

[0053] According to the example, the second flexible drive 22 is likewise embodied as a chain drive 22 and comprises a first drive pulley 13, which is identical with the second output 13. In addition, the second flexible drive 22 comprises a second output pulley 17 and a second chain 18. The second output 13 or first drive pulley 13 is likewise connected for conjoint rotation to the ring gear of the planetary gear 16, and the second output pulley 17 is connected for conjoint rotation to the second steering knuckle 5.

[0054] In this case, the first drive pulley 12 is arranged above the second drive pulley 13.

[0055] As can be seen, the first drive pulley 12 and the second drive pulley 13 have a substantially rectangular shape with rounded corners, wherein on each drive pulley 12, 13 two diagonally opposite edges are rounded to a greater or lesser extent than the two other diagonally opposite edges. The running surface for the first chain 15 or the second chain 18 follows this rectangular shape with rounded edges. This results in a non-linear relationship between a rotation of the respective drive pulley 12, 13 and the associated output pulley 14, 17. By virtue of this different actuation of the first steering knuckle 4 and of the second steering knuckle 5, it is possible in a simple manner to ensure that the Ackermann condition is always satisfied for each steering angle. This results in reduced tire wear as well as a reduced energy requirement when cornering.

[0056] As can furthermore be seen, the first drive pulley 12 has a fixed rotational offset with respect to the second drive pulley 13. Like the geometric deviation of the first drive pulley 12 and the geometric deviation of the second drive pulley 13 from the circular shape, the rotational offset angle contributes to satisfying the Ackermann condition at each steering angle. By means of the selection of the rotational offset and the precise geometric design of the running surfaces of the first drive pulley 12 and of the second drive pulley 13 from the circular shape, the Ackermann condition can be set in each case for different track widths and wheelbases.

[0057] According to the example, the first output pulley 14 and the second output pulley 17, on the other hand, have a circular running surface.

[0058] FIG. 2 shows the steering axle 20 according to FIG. 1 in a view from above. As can be seen, the steerable wheels 2, 3 of the steering axle 20 are turned. In order to avoid slipping of the wheels 2, 3 during cornering, the wheels 2, 3 have the so-called Ackermann angle with respect to one another, i.e. two orthogonal lines 23, 24 to the axes of rotation of the steerable wheels 2, 3 always intersect at an intersection point 25 which lies on a straight line congruent with a front axle (not illustrated) of the steerable vehicle. Since the Ackermann condition is thus completely satisfied, the wheels 2, 3 can move exclusively in a rolling manner at any time. As a result, in turn, tire wear and the energy requirement during cornering are significantly reduced.

[0059] FIG. 3 shows schematically and in part the steering motor 6 and the steering gear 16 on the axle housing 1 in a common housing 9. A motor shaft 110 of the steering motor 6 embodied as an electric motor 6 drives a first sun wheel 111, which meshes with first planet wheels 112. These, in turn, drive the first planet carrier 113, which is connected for conjoint rotation to a second sun wheel 114. The second sun wheel 114 meshes with second planet wheels 115, which drive a second planet carrier 116. The latter is connected for conjoint rotation to a third sun wheel 117, the third sun wheel 117 meshing with third planet wheels 118. The third planet wheels 118 drive the third planet carrier 119, which is connected for conjoint rotation to the axle bridge 1. According to the example, it is screwed to the axle housing 1. All the planet wheels 112, 115, 118 mesh with the ring gear 120, with the result that the latter rotates about its own axis. The ring gear 120 is connected for conjoint rotation to the ring gear carrier 121, on which, in turn, the two drive wheels 12, 13 are arranged for conjoint rotation. As an example, the round planet carrier pins 129 engage directly into the axle housing 1 and thus ensure low-cost and reliable alignment and rotation prevention of the third planet carrier 119 and of the third planet wheels 118 relative to the axle housing 1.

[0060] FIG. 4 shows schematically another possible embodiment of a steering axle 20 according to the invention for a steerable vehicle in cross section. As can be seen, according to the embodiment of FIG. 4, the steering motor 6 is arranged below the axle housing 1, and the steering gear 16 is arranged inside the axle housing 1. In this case, the ring gear carrier 121 is connected to the axle housing 1 for conjoint rotation via a flange region, and the first drive pulley 12 and the second drive pulley 13 are firmly screwed to the third planet carrier 119. The steering motor 6 is thus connected for conjoint rotation to the axle housing 1. The overall height of the steering axle 20 is thereby kept low.

[0061] It can furthermore be seen that an electronic steering angle sensor 122 detects a set steering angle without contact.

REFERENCE SIGNS

[0062] 1 axle housing [0063] 2 first wheel [0064] 3 second wheel [0065] 4 first steering knuckle [0066] 5 second steering knuckle [0067] 6 steering motor [0068] 9 common housing [0069] 12 first drive pulley [0070] 13 second drive pulley [0071] 14 first output pulley [0072] 15 first flexible drive means, first chain [0073] 16 steering gear, planetary gear [0074] 17 second output pulley [0075] 20 steering axle, portal axle [0076] 21 first flexible drive, first chain drive [0077] 22 second flexible drive, second chain drive [0078] 23 orthogonal line [0079] 24 orthogonal line [0080] 25 intersection point [0081] 110 motor shaft [0082] 111 first sun wheel [0083] 112 first planet wheels [0084] 113 first planet carrier [0085] 114 second sun wheel [0086] 115 second planet wheels [0087] 116 second planet carrier [0088] 117 third sun wheel [0089] 118 third planet wheels [0090] 119 third planet carrier [0091] 120 ring gear [0092] 121 ring gear carrier [0093] 122 electronic steering angle sensor [0094] 129 planet carrier pins