Machine element or mechanism – Engine starters – Automatic
Patent
1992-02-22
1994-06-07
Herrmann, Allan D.
Machine element or mechanism
Engine starters
Automatic
74 7E, 192 45, F02N 1102
Patent
active
053179331
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a starting device, in particular a freely disengaging starting device, with an electric motor, the rotor of which drives, via a free-wheeling clutch, a driven shaft which has a pinion for the drive of an internal combustion engine gear ring. In this starting device the end section of the driven shaft which carries the pinion is supported in a front face of the housing (DE-OS 39 08 870 ).
In motor vehicle technology, such starting devices are used for starting the vehicle engines. For the starting procedure, a pinion of the starting device moves into mesh with the engine gear ring. For the required axial movement of the pinion, a driven shaft which carries it is supported so as to be axially movable. When the starting procedure is complete, the pinion disengages from the gear ring, whereupon the driven shaft returns to its starting position. The axial movement of the driven shaft takes place preferably via a coarse pitch helix. A free-wheel device is further provided which effects a torque transmission in one direction of rotation and a disengagement in the other direction, so that after the engine has started, an "overrun" of the starting device is possible, resulting in a withdrawal of the pinion.
Due to the system for the axial displacement of the driven shaft and for the free-wheel arrangement and the required support points, the resulting physical length of such starting devices is relatively large, and becomes even larger, if they are configured as gear starters.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved starter device, which has an improved structure, facilitating construction of more compact starting devices, than those of the prior art.
In contrast, the invention in accordance with the main claim with the specified features has the advantage that a short and physically light form can be achieved. The driven shaft is supported via a first bearing in a central aperture of a free-wheel outer ring of the free-wheel device. The surface of the free-wheel ring is supported via a second bearing on the starting device housing. At the driven shaft end section which lies within the housing, the associated end of the starter motor rotor shaft is supported via a third bearing. This design in accordance with the invention results in the driven shaft being fixedly supported via the free-wheel outer ring inside the housing, with an end section of the driven shaft at the same time providing a bearing point for the appropriately facing end of the starter rotor. This design facilitates a compact and simple structure, since the number of bearing points which are directly supported on the starting device housing, is reduced.
According to a preferred embodiment example, the first bearing is a radial bearing, in particular designed as a rolling contact bearing. It may preferably be a needle bearing.
The second bearing--like the radial bearing-- absorbs the radial forces, while, it also absorbs the axial forces, i.e. it is designed as an axial bearing, whereby axial fixing of the free-wheel outer ring takes place. In particular, it can be designed as a rolling contact bearing, preferably as a ball bearing, in particular as a deep groove ball bearing.
The third bearing again is a radial bearing, in particular a rolling contact bearing. here again, the rolling contact bearing may be designed as a needle bearing.
In accordance with a preferred embodiment example, the rotor shaft has an axial location hole in which the third bearing is arranged and into which the end of the driven shaft projects. The rotor shaft and the driven shaft thus run coaxially, whereby due to the engagement of the driven shaft in the location hole of the rotor shaft, "interleaving" results, which contributes to the small physical length of the starting device of the invention.
It is of advantage, if the other end section of the rotor shaft is supported in a fourth bearing, in particular a needle bearing, which is arranged in a first break-through in
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patent: 4440033 (1984-04-01), Kurihara et al.
patent: 4800766 (1989-01-01), Isozumi et al.
patent: 5012686 (1991-05-01), Morishita et al.
Mark's, Standard Handbook for Mechanical Engineers, Ninth Edition, McGraw-Hill, N.Y., 1987, pp. 8-131 to 8-133.
Herrmann Allan D.
Laub David W.
Robert & Bosch GmbH
Striker Michael J.
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