Steering axle for a forklift truck

Abstract

Steering axle for a forklift truck, with an axle bridge (1) in the two end regions of which a first axle housing (2) is pivotably arranged about a first vertical steering axis (3) and a second axle housing (4) about a second vertical steering axis (5), each carrying a wheel (6, 7), with a rotary drive arranged centrally of the axle bridge (1), from whose output axis (11) the axle housings (2, 4) can be pivotably driven directly or indirectly via transmission means, wherein a radial lever arrangement can be pivotably driven from the output axis (11), which has one or two lever elements (13, 14) extending horizontally radially to the output axis (11), to which a first tie rod (15) and a second tie rod (16) are articulated at their ends, wherein the first tie rod (15) leads to a first axle housing lever (17),which extends horizontally and is rigidly connected to the first axle housing (2) and to which the first tie rod (15) is articulated at a radial distance to the first steering axis (3), and wherein the second tie rod (16) leads to a second axle housing lever (18) which extends horizontally and is rigidly connected to the second axle housing (4) and to which the second tie rod (16) is articulated at a radial distance to the second steering axis (5), characterized in that the rotary drive is an electric motor and a planetary gear (9) arranged vertically in the axle bridge (1) can be driven by the vertical output shaft (11) of the electric motor (10), the radial lever arrangement being pivotably driven by the output shaft (12) of the planetary gear (9), the speed of the output shaft (11) of the electric motor (10) being driven by the planetary gear (9) in a reduction manner.

Description

[0001] The invention relates to a steering axle for a forklift truck, comprising an axle bridge in the two end regions of which a first axle housing and a second axle housing are pivotably arranged about a first vertical steering axis and a second axle housing about a second vertical steering axis, each carrying a wheel, with a rotary drive arranged centrally of the axle bridge, from whose output shaft the axle housings can be pivotably driven directly or indirectly via transmission means, wherein a radial lever arrangement can be pivotably driven from the output shaft, the arrangement having one or two lever elements extending horizontally radially to the output shaft, to which a first tie rod and a second tie rod are articulated at their ends, the first tie rod leading to a first axle housing lever.which extends horizontally and is rigidly connected to the first axle housing and to which the first tie rod is articulated at a radial distance to the first steering axis, and wherein the second tie rod leads to a second axle housing lever which extends horizontally and is rigidly connected to the second axle housing and to which the second tie rod is articulated at a radial distance to the second steering axis.

[0002] In such a steering axle for a forklift truck, it is known that the transmission means include a coupling spur gear rotatably driven by the electric motor, from which two connecting shafts parallel to the output shaft of the electric motor are rotatably driven, each connecting shaft driving a belt of a belt drive which wraps around a pulley connected to the respective axle housing. When the output shaft is driven by the electric motor, a pivoting drive of the axle housings is achieved via the belt drive.

[0003] This training is complex, involves a large number of components that require a large installation space and must be carefully coordinated.

[0004] The object of the invention is to create a steering axle for a forklift truck of the type mentioned above, which avoids these disadvantages and has a compact and cost-effective design with few simple components.

[0005] A steering axle of the type mentioned above is known from WO 88 / 07953 A1.

[0006] From DE 10 2009 002 935 A1, a steerable vehicle axle is known in which a spindle nut is rotatably driven by an electric motor via a planetary gear. A tie rod extending parallel to the axle beam is designed as a threaded spindle and can be driven translationally by the spindle nut. Tie rod levers are articulated to opposite ends of the tie rod, which are articulated to axle housing levers. The axle housing levers, in turn, are rotationally fixed to the axle heads via radially oriented pivot joints.

[0007] This problem is solved according to the invention in that the rotary drive is an electric motor and a planetary gear arranged vertically in the axle bridge can be driven by the vertical output shaft of the electric motor, the radial lever arrangement can be pivotably driven by the output shaft of which the radial lever arrangement can be driven, wherein the speed of the output shaft of the electric motor can be driven by the planetary gear in a reduction manner.

[0008] Preferably, the axle bridge is a cast component.

[0009] This design uses only a few simple components that are easy to assemble and require little installation space.

[0010] Due to the lower rotational speed of the output shaft compared to the output shaft of the planetary gear, the torque on the output shaft is greater than the torque of the electric motor.

[0011] To protect against contamination and mechanical damage, the electric motor and / or the planetary gear can be arranged in a housing permanently connected to the axle bridge.

[0012] A further reduction in the number of components can be achieved by designing the axle bridge and the housing of the electric motor and / or the planetary gear as a single unit, whereby the axle bridge fulfills a dual function.

[0013] This design is easy to manufacture if the axle bridge and housing are designed as a cast component.

[0014] If the ring gear of the planetary gear is fixedly arranged in a housing bore formed in the axle bridge, the required installation space and the number of components are further reduced.

[0015] The ring gear can be fixed in place, for example by pressing it into the housing bore.

[0016] A reduction in the number of components also results if the first axle housing lever is formed as one piece with the first axle housing and the second axle housing lever is formed as one piece with the second axle housing.

[0017] If the lever elements of the forklift truck extend at least approximately in the opposite direction to the axle housing levers when traveling straight ahead, a toggle-lever effect is created, particularly at maximum wheel steering angle. This increases the tensile and compressive forces in the tie rods, counteracting the increasing torque loss at the wheel due to the decreasing effective length of the axle housing levers. Thus, at maximum wheel steering angle, the toggle-lever effect provides more steering torque at the wheel.

[0018] The freedom of movement of the steering axis according to the invention can also be used to reduce the steering angle error and for larger steering angles.

[0019] The lever elements extending horizontally radially to the output axis can be a single component to which both the first tie rod and the second tie rod are articulated at their ends, leading to a further reduction in the number of components.

[0020] An embodiment of the invention is shown in the drawing and is described in more detail below. The drawing shows... Fig. 1. A schematic representation in the straight-ahead driving position of a steering axle in side view Fig. 2. A schematic representation in the straight-ahead driving position, top view of the steering axis. Fig. 1 Fig. 3 a perspective view of a steering axle according to Fig. 1.

[0021] The steering axle shown in the figures for a material handling vehicle, in particular for a forklift truck, has an axle bridge 1 which is fixedly arranged on a frame of the material handling vehicle (not shown). The steering axle is a rear axle of the material handling vehicle.

[0022] At one end of the axle bridge 1, a first axle housing 2 is arranged to pivot about a first vertical steering axis 3.

[0023] At the second end area of ​​the axle bridge 1, a second axle housing 4 is pivotably arranged about a second vertical steering axis 5.

[0024] Each axle housing 2, 4 carries a wheel 6, 7.

[0025] In the center of the axle bridge 1, which is designed as a cast component, a housing bore 8 is formed vertically in the axle bridge 1, in which a planetary gear 9 is arranged.

[0026] The planetary gear 9 can be driven around a vertical output axis 11 by a reversible electric motor 10, which is attached to the axle bridge 1 concentrically to the planetary gear 9.

[0027] On a vertical output shaft 12 of the planetary gear 9 which is coaxial to the output axis 11, two lever elements 13, 14 projecting radially away from the output shaft are arranged as a single component and can be pivotably driven by the planetary gear 9.

[0028] At the free end of the first lever element 13, one end of a first tie rod 15 is attached, and at the free end of the second lever element 14, one end of a second tie rod 16 is attached.

[0029] The second end of the first tie rod 15 is articulated at a radial distance to the first steering axis 3 at the free end of a first axle housing lever 17, which is formed in one piece with the first axle housing 2 and extends radially to the first steering axis 3.

[0030] The second end of the second tie rod 16 is articulated at a radial distance to the second steering axis 5 at the free end of a second axle housing lever 18, which is formed integrally with the second axle housing 4 and extends radially to the second steering axis 5.

[0031] The lever elements 13, 14 extend at least approximately in the opposite direction to the axle housing levers 17, 18 when the forklift truck is traveling straight ahead as shown. Reference sign 1 axle bridge 2 first axle housing 3 first steering axle 4 second axle housing 5 second steering axle 6 wheels 7 wheel 8 Housing bore 9 planetary gears 10 Electric motor 11 Output axle 12 Output shaft 13 first lever element 14 second lever element 15 first tie rod 16 second tie rod 17 first axle housing lever 18 second axle housing lever

Claims

[1] Steering axle for a forklift truck, with an axle bridge (1) in the two end regions of which a first axle housing (2) is pivotably arranged about a first vertical steering axis (3) and a second axle housing (4) about a second vertical steering axis (5), each carrying a wheel (6, 7), with a rotary drive arranged centrally of the axle bridge (1), from whose output axis (11) the axle housings (2, 4) can be pivotably driven directly or indirectly via transmission means, wherein a radial lever arrangement can be pivotably driven from the output axis (11), which has one or two lever elements (13, 14) extending horizontally radially to the output axis (11), to which a first tie rod (15) and a second tie rod (16) are articulated at their ends, wherein the first tie rod (15) leads to a first axle housing lever (17),which extends horizontally and is rigidly connected to the first axle housing (2) and to which the first tie rod (15) is articulated at a radial distance to the first steering axis (3) and wherein the second tie rod (16) leads to a second axle housing lever (18) which extends horizontally and is rigidly connected to the second axle housing (4) and to which the second tie rod (16) is articulated at a radial distance to the second steering axis (5), , characterized by , that the rotary drive is an electric motor and a planetary gear (9) arranged vertically in the axle bridge (1) with a housing bore (8) can be driven by the vertical output shaft (11) of the electric motor (10), the radial lever arrangement can be pivotably driven by the output shaft (12) of which the radial lever arrangement can be pivotably driven, wherein the speed of the output shaft (11) of the electric motor (10) can be driven by the planetary gear (9) in a reduction manner. [2] Steering axle according to claim 1 , characterized by, that the electric motor and / or the planetary gear (9) are arranged in a housing fixedly connected to the axle bridge (1). [3] Steering axle according to claim 2, characterized by , that the axle bridge (1) and the housing of the electric motor and / or the planetary gear (9) are formed in one piece. [4] Steering axle according to claim 3, characterized by , that the ring gear of the planetary gear (9) is fixedly arranged in a housing bore (8) formed in the axle bridge (1). [5] Steering axle according to one of the preceding claims, characterized by , that the first axle housing lever (17) is formed in one piece with the first axle housing (2) and the second axle housing lever (18) is formed in one piece with the second axle housing (4). [6] Steering axle according to one of the preceding claims, characterized by , that the lever elements (13, 14) extend at least approximately in the opposite direction to the axle housing levers (17, 18) when the industrial truck is traveling straight ahead. [7] Steering axle according to one of the preceding claims, characterized by , that the lever elements (13, 14) extending horizontally radially to the output axis (11) are a single component to which both the first tie rod (15) and the second tie rod (16) are articulated at their ends.

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