STEERING DRIVE FOR A STEERING AXLE OF A STEERABLE VEHICLE, STEERING AXLE, AND INDUSTRIAL TRUCK

Abstract

A steering drive includes an electric motor with a motor shaft and a steering lever rotatable about a pivot axis. A first planetary stage has a first sun gear, first planet gears, a first ring gear, and a first planet carrier. A final planetary stage has a final sun gear, final planet gears, a final ring gear, and a final planet carrier. A force flow runs from the motor shaft to the first sun gear, and from the first sun gear via the first planet gears to the first planet carrier and to the first ring gear. The force flow runs via the final sun gear and via the final planet gears to the final ring gear, runs from the first ring gear and from the final ring gear to the steering lever, and runs via a first sun gear shaft from the electric motor to the first sun gear.

Claims

1. A steering drive (30) for a steering axle of a steerable vehicle, comprising: an electric motor (1) with a motor shaft (2); a first planetary stage (31) with a first sun gear (4) with a first sun gear shaft (3), first planet gears (5), a first ring gear (7), and a first planet carrier (6); a final planetary stage (33) with a final sun gear (12) defining a bore, final planet gears (13), a final ring gear (14), and a final planet carrier (34), wherein the first sun gear shaft (3) is arranged rotatably within the bore of the final sun gear (12); and a steering lever (35) rotatable about a pivot axis (27); wherein the steering drive (30) is configured such that a force flow runs from the motor shaft (2) to the first sun gear (4), such that the force flow furthermore runs from the first sun gear (4) via the first planet gears (5) to the first planet carrier (6) and to the first ring gear (7), such that the force flow furthermore runs via the final sun gear (14) and via the final planet gears (13) to the final ring gear (14), and such that the force flow runs from the first ring gear (7) and from the final ring gear (14) to the steering lever (35), and such that the force flow from the electric motor (1) to the first sun gear (4) runs via the first sun gear shaft (3).

2. The steering drive (30) as claimed in claim 1, wherein the steering drive (30) furthermore comprises a housing which has a carrier (28), the carrier (28) being arranged axially between the electric motor (1) and the final planetary stage (33).

3. The steering drive (30) as claimed in claim 2, wherein the final planet carrier (34) is connected rotationally conjointly to the carrier (28).

4. The steering drive (30) as claimed in claim 2, wherein the carrier (28) has a flange region (17) that is suitable for a screw connection of the steering drive (30) to an axle housing of the steering axle.

5. The steering drive (30) as claimed in claim 2, wherein the final planet carrier (34) and the carrier (28) are braced axially via a pivot bearing assembly (19) of the steering lever (35) by means of a locknut (21).

6. The steering drive (30) as claimed in claim 2, wherein the motor shaft (2) has a gearbox-side bearing assembly (36) arranged in the final planet carrier (34) or in the carrier (28).

7. The steering drive (30) as claimed in claim 1, wherein the motor shaft (2) and the first sun gear shaft (3) are formed as a single piece.

8. The steering drive (30) as claimed in claim 1, wherein the steering drive (30) furthermore comprises at least one middle planetary stage (32) which in turn comprises a middle sun gear (8), middle planet gears (9), a middle ring gear (10), and a middle planet carrier (11), the force flow running from the first planet carrier (6) via the middle sun gear (8) and the middle planet gears (9) to the middle planet carrier (11) and to the middle ring gear (10), and the force flow furthermore running from the middle planet carrier (11) to the final sun gear (12) and from the middle ring gear (10) to the steering lever (35).

9. The steering drive (30) as claimed in claim 8, wherein the first ring gear (7), the final ring gear (14) and/or the middle ring gear (10) have identical toothings.

10. The steering drive (30) as claimed in claim 1, further comprising axial plain bearings (22, 23, 24, 25, 26) or axial roller bearings arranged at planar surfaces of components of the steering drive (30) which are rotatable relative to one another.

11. A steering axle comprising a steering drive (30) as claimed in claim 1.

12. An industrial truck comprising a steering axle as claimed in claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The invention will be discussed by way of example below on the basis of embodiments illustrated in the figures.

[0040] In the figures:

[0041] FIG. 1 shows, by way of example and schematically, a possible embodiment of a steering drive according to the invention for a steering axle of a steerable vehicle, and

[0042] FIG. 2 shows, by way of example and schematically, the steering drive of FIG. 1 in a perspective view.

DETAILED DESCRIPTION

[0043] Identical objects, functional units and similar components are denoted by the same reference designations throughout the figures. These objects, functional units and similar components are of identical design in terms of their technical features unless explicitly or implicitly stated otherwise in the description.

[0044] FIG. 1 shows, by way of example and schematically, a possible embodiment of a steering drive 30 according to the invention for a steering axle (not illustrated) of a steerable vehicle (likewise not illustrated).

[0045] The steering drive 30 comprises an electric motor 1 with a motor shaft 2 and comprises a first planetary stage 31 with a first sun gear 4, first planet gears 5, a first ring gear 7 and a first planet carrier 6. The steering drive 30 also comprises a first sun gear shaft 3, which is connected rotationally conjointly and axially displaceably to the motor shaft 2 and to the first sun gear 4.

[0046] The steering drive 30 furthermore comprises a middle planetary stage 32 with a middle sun gear 8, middle planet gears 9, a middle ring gear 10 and a middle planet carrier 11.

[0047] The steering drive 30 finally also comprises a final planetary stage 33 with a final sun gear 12, final planet gears 13, a final ring gear 14 and a final planet carrier 34.

[0048] The steering drive 30 of FIG. 1 likewise also comprises a steering lever 35 which is configured as a double lever 35 and which, in the example, is formed as a single piece with a pot-shaped lower part 15 of the housing of the steering drive 30. In this way, there is advantageously no need to provide an oil-tight seal that seals off the steering lever with respect to the gearbox.

[0049] In the example, the first ring gear 7, the middle ring gear 10 and the final ring gear 14 are formed as a single piece. The middle ring gear 10 and the final ring gear 14 furthermore have an identical toothing. Only the first ring gear 7 has a different toothing.

[0050] The first ring gear 7, the middle ring gear 10 and the final ring gear 14 are connected rotationally conjointly, by way of a spline toothing, to the lower part 15 of the housing and thus to the steering lever 35.

[0051] A force flow in the steering drive 30 runs from the motor shaft 2 via a first sun gear shaft 3 to the first sun gear 4. The force flow runs onward from the first sun gear 4 via the first planet gears 5 to the first planet carrier 6 and to the first ring gear 7. Since the first planet carrier 6 is connected rotationally conjointly to the middle sun gear 8, the force flow runs onward from the middle sun gear 8 via the middle planet gears 9 to the middle ring gear 10 and to the middle planet carrier 11. The middle planet carrier 11 is in turn connected rotationally conjointly to the final sun gear 12, and therefore the force flow runs from the middle planet carrier 11 to the final sun gear 12. From there, the force flow runs onward to the final planet gears 13 and to the final ring gear 14. The final planet carrier 34 is connected rotationally conjointly to a carrier 28 of the housing, which carrier is, in the example, composed of two parts connected to one another via a spline toothing 20. The carrier 28 is furthermore connected rotationally conjointly to the electric motor 1. An axis of rotation of the motor shaft 2 of the electric motor 1 is simultaneously the pivot axis 27.

[0052] The steering lever 35 can thus be pivoted about a bearing assembly 19 by means of the electric motor 1. A movement of the steering lever 35 in turn causes an adjustment of the steering position of the steered wheels of the steering axle. For example, the steering axle may have an Ackermann steering system that is steered by the steering drive 30. Forces or torques are transmitted via the bearing arrangement 19 into the carrier 28.

[0053] Via a flange region 17 with bores 18, the steering drive 30 can be arranged reliably and rotationally conjointly on the steering axle. For the exact alignment of the steering drive 30 with the steering axle, the flange region may for example have alignment pins which can be guided with very little play in corresponding bores of the steering axle.

[0054] Furthermore, a bearing assembly 36 of the motor shaft is arranged in the carrier 28, such that the steering drive 30 is of axially relatively short construction.

[0055] As can also be seen in FIG. 1, the first sun gear shaft 3 is guided rotatably through a bore of the final sun gear 12 and of the middle sun gear 8.

[0056] A locknut 21 braces the final planet carrier 34 together with the carrier 28 via the inner ring of the bearing assembly 19 and thus holds said final planet carrier in position axially.

[0057] Components of the steering drive 30 that are rotatable relative to one another are mounted rotatably by means of axial plain bearings 22, 23, 24, 25, 26.

[0058] FIG. 2 shows, by way of example and schematically, the steering drive 30 of FIG. 1 in a perspective view. In particular, the pot-shaped form of the lower part 15 of the housing can be clearly seen in this view.

[0059] It is furthermore possible to see the pivot axis 27 and the steering lever 35, configured as a double lever 35, with the lever axis 16 through the bores 37.

REFERENCE SIGNS

[0060] 1 Electric motor
2 Motor shaft
3 First sun gear shaft
4 First sun gear
5 First planet gear
6 First planet carrier
7 First ring gear
8 Middle sun gear
9 Middle planet gear
10 Middle ring gear
11 Middle planet carrier
12 Final sun gear
13 Final planet gear
14 Final ring gear
15 Lower part of the housing
16 Lever axis
17 Flange region

18 Bore

[0061] 19 Bearing assembly
20 Spline toothing

21 Locknut

[0062] 22 Axial plain bearing
23 Axial plain bearing
24 Axial plain bearing
25 Axial plain bearing
26 Axial plain bearing
27 Pivot axis

28 Carrier

[0063] 30 Steering drive
31 First planetary stage
32 Middle planetary stage
33 Final planetary stage
34 Final planet carrier
35 Steering lever
36 Bearing assembly