Electric kingpin steering of a vehicle axle

Abstract

An electric kingpin steering system for a vehicle axle with an electrically actuated and non-self-locking steering gear (2) is proposed, wherein at least one electrically actuated braking device (3) is provided to lock the steering gear (2) in the event of a power supply failure. Furthermore, a forklift truck with the kingpin steering system is proposed.

Description

[0001] The present invention relates to an electric steering knuckle system for a vehicle axle with an electrically operated and non-self-locking steering gear. Furthermore, the invention relates to an industrial truck with the electric steering knuckle system.

[0002] Electrically operated steering knuckle systems are generally known from automotive engineering. These systems comprise a steering gear that is actuated, for example, by an electric drive motor, with which the tie rods of a vehicle axle can be moved to steer the vehicle wheels. Due to their design, electrically operated steering knuckle systems do not have a self-locking mechanism. As a result, the steering gear can be moved in an undesired manner by external forces acting on the steering. Relatively small external forces are sufficient for this. In the event of a system failure or a failure of the electrical power supply, with the steering gear in a de-energized state, there is a risk that the vehicle could experience undesired steering movements while decelerating to a standstill. These movements are caused by wheel forces resulting from the driving movement and cause the steering to operate in an undesired manner.

[0003] Accordingly, the object of the present invention is to propose an electric steering knuckle and an industrial truck with the steering knuckle, in which an undesired adjustment of the steering gear is prevented in a structurally simple and cost-effective manner in the event of a failure of the electrical power supply.

[0004] This object is achieved according to the invention by the features of patent claims 1 and 10, respectively. Advantageous and claimed developments emerge from the subclaims and the description as well as the drawings.

[0005] Thus, an electric steering knuckle of a vehicle axle with an electrically operated and non-self-locking steering gear is proposed. To prevent undesired steering movements of the steering gear in the event of a system failure in the de-energized state, at least one electrically operated braking device is provided to lock the steering gear. This braking device is closed in the event of a power failure.

[0006] In this way, the braking device, which can be released by applying an electrical voltage and the braking device that engages in the event of a power failure, is assigned to the steering gear in such a way that, in the event of a system failure, the braking device prevents the steering knuckle from performing unwanted steering movements due to external forces by counteracting the steering movement with braking resistance or a braking torque. Consequently, the vehicle maintains its direction of travel in the event of a system failure.

[0007] A particularly simple and cost-effective design for locking the steering gear in the event of a power failure can be achieved by using an electrically releasable spring-loaded friction brake as the braking device. Consequently, in the event of a power failure, the braking device is closed almost automatically due to the mechanical spring force acting on the friction elements, thus locking the steering gear. Consequently, no additional control of the braking device is required.

[0008] It is particularly advantageous if the braking torque generated by the braking system is adjustable or variable. This allows a desired braking resistance to be applied to counteract a steering movement of the steering gear caused by external influences. For example, it is possible to adjust the braking torque or the spring force acting on the friction elements in such a way that emergency actuation of the steering is possible even in the event of a system failure.

[0009] The proposed steering knuckle system can accommodate any mechanically designed electrically operated steering gear. The required gear ratio is implemented in a simple and thus space-saving manner using a spur gear or a planetary gear as the steering gear.

[0010] In order to ensure that the steering gear is blocked in the event of a system failure, the proposed steering knuckle system provides that the braking device is coupled to a shaft of the steering gear in such a way that a transmission output shaft of the steering gear is blocked or braked in the event of a failure of the electrical power supply.

[0011] A particularly structurally simple and cost-effective steering knuckle can be realized by coupling a transmission input shaft of the steering gear to a drive shaft of an electric drive motor of the steering gear and a transmission output shaft of the steering gear to a movable lever or the like for actuating the associated tie rods for steering the vehicle wheels of the vehicle axle.

[0012] With this type of steering system, it is particularly advantageous if the brake bodies or friction elements of the braking system are assigned to the drive shaft of the electric drive motor to decelerate and lock the steering gear. However, other coupling options for the braking system are also conceivable, provided they are equally simple to implement.

[0013] In order to realize a particularly structurally simple and thus space-saving arrangement in the proposed axle steering system, the braking device and the electric drive motor can be arranged coaxially to a rotation axis.

[0014] With such an alignment, it is particularly advantageous if the steering gear, the electric drive motor, and the braking system are arranged axially next to each other. Preferably, the rotation axis can be aligned approximately perpendicular to a horizontally extending axle bridge. However, other arrangements of the various components are also possible, if the installation situation allows it.

[0015] The object underlying the invention is also achieved by an industrial truck with the aforementioned electric knuckle steering system. The installation of the knuckle steering system in the industrial truck realizes the advantages already described and others. In particular, the vehicle design is particularly simple and thus requires minimal installation space.

[0016] The present invention is further explained below with reference to the drawings.

[0017] They show: Fig. 1 is a schematic front view of a vehicle axle with an electric steering knuckle according to the invention on an industrial truck; and Fig. 2 a schematic plan view of the vehicle axle with the electric steering knuckle.

[0018] In Fig. 1 and Fig. 2 shows, by way of example, a possible embodiment variant of an electric axle steering system according to the invention of a vehicle axle of an industrial truck 1 which is only indicated schematically.

[0019] The steering knuckle comprises an electrically operated and non-self-locking steering gear 2 and an electrically operated braking device 3 for blocking the steering gear 2, which is closed in the event of a failure of the electrical power supply. In this way, undesired steering movements, which can occur due to external influences in the event of a failure of the electrical power supply, are reliably prevented in the steering knuckle.

[0020] An electric drive motor 4 is assigned to the steering gear 2 of the steering knuckle system, which drives the steering gear 2. For this purpose, a drive shaft of the electric drive motor 4 is connected to a transmission input shaft of the steering gear 2. A transmission output shaft of the steering gear 2 is connected to a lever 5, which actuates the two tie rods 6, 7. The tie rods 6, 7 are coupled to associated steering knuckles 8, 9, which rotate about steering axes 10, 11 and thus execute the steering movement at the vehicle wheels 12, 13.

[0021] The braking device 3 is designed as a releasable spring-loaded friction brake, which has friction elements that can be compressed by spring force. The spring-actuated braking device 3 is designed such that, in the de-energized state, it is closed due to the spring force, since the friction elements are pressed together. The friction elements of the braking device 3 are assigned to the drive shaft of the electric drive motor 4, so that in the event of a power supply failure, the braking device 3 blocks the drive shaft of the electric drive motor 4 due to the compressed friction elements. The braking torque generated by the friction elements of the braking device 3 is supported on an axle bridge 15.

[0022] Since the drive shaft of the electric drive motor 4 is connected to the transmission input shaft of the steering gear 2, blocking the electric drive motor 4 also blocks the steering gear 2 and thus also the lever 5 of the steering gear, so that no steering movement can take place in the event of a failure of the electrical power supply.

[0023] The braking device 3 and the electric drive motor 4 are arranged coaxially with a rotational axis 14. The housings of the steering gear 2 and the electric drive motor 4, as well as the braking device 3, are attached to the axle bridge 15 of the vehicle axle. Furthermore, the steering gear 2 and the electric drive motor 4, as well as the braking device 3, are arranged axially adjacent to one another with respect to the rotational axis 14. The rotational axis 14 is aligned approximately perpendicular to the axle bridge 15. Furthermore, the rotational axis 14 runs axially parallel to the steering axes 10, 11 of the steering knuckles 8, 9. Reference symbol 1 industrial truck 2 steering gears 3 Braking device 4 electric drive motor 5 levers 6 Tie rod 7 Tie rod 8 steering knuckles 9 steering knuckles 10 Steering axis 11 Steering axis 12 vehicle wheel 13 Vehicle wheel 14 Rotation axis 15 axle bridge

Claims

[1] Electric steering knuckle of a vehicle axle with an electrically operated and non-self-locking steering gear (2), characterized by that at least one electrically operated braking device (3) which is closed in the event of a failure of an electrical power supply is provided for blocking the steering gear (2). [2] Electric steering knuckle according to claim 1, characterized by that an electrically releasable spring-loaded friction brake is provided as the braking device (3). [3] Electric steering knuckle according to claim 1 or 2, characterized by that a braking torque of the braking device (3) is adjustable. [4] Electric steering knuckle according to one of the preceding claims, characterized by that the steering gear (2) is designed as a spur gear or as a planetary gear. [5] Electric steering knuckle according to one of the preceding claims, characterized bythat the braking device (3) is coupled to a shaft of the steering gear (2) in such a way that a transmission output shaft of the steering gear (2) is blocked in the event of a failure of the electrical power supply. [6] Electric steering knuckle according to one of the preceding claims, characterized by that a transmission input shaft of the steering gear (2) is connected to a drive shaft of an electric drive motor (4) of the steering gear (2) and a transmission output shaft of the steering gear (2) is connected to a movable lever (5) for actuating the associated tie rods (6, 7) for steering the vehicle wheels (12, 13) of the vehicle axle, and that friction elements of the braking device (3) are associated with the drive shaft of the electric drive motor (4) for blocking the steering gear (2). [7] Electric steering knuckle according to claim 6, characterized bythat the braking device (3) and the electric drive motor (4) are arranged coaxially to a rotation axis (14). [8] Electric steering knuckle according to one of claims 7, characterized by that the steering gear (2) and the electric drive motor (4) as well as the braking device (3) are arranged axially next to one another with respect to the axis of rotation (14). [9] Electric steering knuckle according to one of claims 7 or 8, characterized by that the rotation axis (14) is aligned approximately perpendicular to a horizontally extending axle bridge (15). [10] Industrial truck (1) with an electric steering knuckle according to one of the preceding claims.

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