Electric power steering system having a rack for moving wheels of a vehicle and method for the initial assembly of an electric power steering system of this kind
The disclosure relates to an electric power steering system having a rack and a pinion shaft. The pinion shaft meshes with a row of teeth of the rack in an assembled state. To facilitate initial assembly and prevent disengagement during subsequent repair. the rack has an assembly portion at one end of the row of teeth. This portion transitions from the operational teeth and is configured to guide the pinion shaft into engagement. The row of teeth includes first teeth with a first tooth height for normal operation, while the assembly portion has second teeth with a second tooth height that is less than the first tooth height.
1 . An electric power steering system, comprising a rack for steering wheels of a vehicle and having a pinion shaft, wherein the pinion shaft meshes with a row of teeth of the rack in an assembled state, and the rack has an assembly portion for an initial assembly of the pinion shaft, only one end of the row of teeth transitioning into the assembly portion, wherein first teeth of the row of teeth each have a first tooth height and the assembly portion has second teeth for interacting with the pinion shaft, the second teeth each having a second tooth height that is less than the first tooth height, wherein the pinion shaft extends, in the assembled state, through a shaft passage of a rack housing, a central portion of the shaft passage having a recess and the pinion shaft and the rack being engaged with one another in a region of the recess, and wherein a central longitudinal axis of the pinion shaft extends, in the assembled state, in parallel with a central longitudinal axis of the shaft passage.
2 . The electric power steering system according to claim 1 , wherein the second tooth height is less than half of the first tooth height.
3 . The electric power steering system according to claim 2 , wherein the first teeth of the rack each have a tooth root and a tooth tip, and the second teeth of the rack each have a tooth root, wherein the tooth root of the second teeth corresponds to the tooth root of the first teeth, the second teeth each being formed without a tooth tip.
4 . The electric power steering system according to claim 1 , wherein the first teeth of the rack each have a tooth root and a tooth tip, and the second teeth of the rack each have a tooth root, wherein the tooth root of the second teeth corresponds to the tooth root of the first teeth, the second teeth each being formed without a tooth tip.
5 . The electric power steering system according to claim 1 , wherein for the initial assembly, a central longitudinal axis of the pinion shaft can be inserted into the shaft passage and arranged within the shaft passage obliquely or transversely to a central longitudinal axis of the shaft passage, as a result of which one end of the pinion shaft can be guided past the assembly portion of the rack.
6 . The electric power steering system according to claim 5 wherein the shaft passage has a plurality of portions having different inside diameters, the central portion of the shaft passage having a first inside diameter and the first inside diameter being the smallest inside diameter of the shaft passage.
7 . The electric power steering system according to claim 6 , wherein starting from the central portion and going outward, the other portions of the shaft passage have inside diameters which increase in steps and/or continuously.
8 . The electric power steering system according to claim 1 , wherein the shaft passage has a plurality of portions having different inside diameters, the central portion of the shaft passage having a first inside diameter and the first inside diameter being the smallest inside diameter of the shaft passage.
9 . The electric power steering system according to claim 1 , wherein the second tooth height is less than a third of the first tooth height.
10 . The electric power steering system according to claim 1 , wherein a central longitudinal axis of the pinion shaft coincides, in the assembled state, with the central longitudinal axis of the shaft passage.
11 . An electric power steering system, comprising a rack for steering wheels of a vehicle and having a pinion shaft, wherein the pinion shaft meshes with a row of teeth of the rack in an assembled state, and the rack has an assembly portion for an initial assembly of the pinion shaft, only one end of the row of teeth transitioning into the assembly portion, wherein first teeth of the row of teeth each have a first tooth height and the assembly portion has second teeth for interacting with the pinion shaft, the second teeth each having a second tooth height that is less than the first tooth height, wherein the pinion shaft extends, in the assembled state, through a shaft passage of a rack housing, a central portion of the shaft passage having a recess and the pinion shaft and the rack being engaged with one another in a region of the recess, and wherein the shaft passage has a plurality of portions having different inside diameters, the central portion of the shaft passage having a first inside diameter and the first inside diameter being the smallest inside diameter of the shaft passage.
12 . The electric power steering system according to claim 11 , wherein starting from the central portion and going outward, the other portions of the shaft passage have inside diameters which increase in steps and/or continuously.