Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Patent
1991-12-10
1992-08-25
Wright, Dirk
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
74475, 384 49, 403109, B60K 2000
Patent
active
051408660
DESCRIPTION:
BRIEF SUMMARY
According to the preamble of claim 1, the invention concerns a gearshift device for a multiple-gear transmission of a motor vehicle including a central selector shaft, rotatable and axially movable in the transmission housing, by whose rotation can be selected a gearshift clutch to be actuated in a gearshift gate and by whose subsequent axial movement gear steps can be engaged, having a selector rocker designed as lever in whose hub the selector shaft is non-rotatably and axially movably passed over roller bodies that engage in axially extending guide grooves of the hub, and can be shifted from its neutral position to a selected end position against the tension of at least one spring element secured to the housing.
In the publication "Muncie, HM-290, Manual Transmission", pages 1-40 and 1-42, a gearshift device of the above kind has been disclosed wherein drag rollers, which engage in longitudinal grooves of the selector rocker, are situated on the selector shaft over radial pins. If a shift gate is selectee by means of a gearshift lever, rotation of the selector shaft, in which the drag rollers move the selector rocker from its central neutral position against the spring elements secured to the housing, results. In the subsequent shift movement, the selector shaft is axially moved so that the drag rollers roll away in the guide grooves of the hub. The drag rollers must have radial backlash within the guide grooves in order that when rolling out on one of the two pathways of the respective guide groove, they can move freely with respect of the other pathway. Without said radial backlash, the drag rollers would cramp in the guide grooves. Due to said radial backlash, an idle path which disadvantageously allows vibrations in the gearshift lever results in the gearshift device in the direction of selection.
The invention is based on the problem of providing a drag and longitudinal movement free of backlash and friction between selector shaft and selector rocker.
According to the characteristic part of claim 1, this problem is solved by the fact that the selector shaft has guide grooves and the roller bodies are designed as balls which, in the radial interspace between the hub and the selector shaft, are situated in a cylindrical cage arranged in several rows extending in an axial direction and are guided by part of their surface in positive engagement in the guide grooves both of the hub and of the selector shaft. Such linear direction is in position to fix absolutely, without backlash with respect to each other, the selector shaft and the selector rocker. The balls arranged in rows on the periphery of the selector shaft take care of an untilting support of the elements with respect to each other so that a small friction occurs between them. A considerable reduction of the shifting forces is thereby possible. The oscillations transmitted to the transmission of the motor vehicle, due to unevenness of rotation of the prime mover, no longer results in vibrations of the gearshift lever by virtue of the rotation between hub and selector shaft drag free of backlash.
Even though publication DE-AS 28 01 182 has disclosed a drive shaft of variable length in which an external portion of the shaft is movable with respect to an internal portion thereof in a linear direction, said device is provided for a telescopable drive shaft.
The invention stated in sub-claim 2 refers to a gearshift device for a multi-gear change gear transmission of a motor vehicle which essentially coincides with the gearshift device according to the preamble of claim 1, but in which the selector shaft in the hub is guided over cylindrical roller bodies.
The problem on which the invention is based is to be solved according to said sub-claim 2 by the fact that the selector shaft has guide grooves, that the guide grooves of the hub and selector shaft are V-shaped, the roller bodies passed into a cage rolling out on respective parallel pathways of the V-shaped guide grooves and the axes of rotation of adjacent roller bodies intersect each other formin
REFERENCES:
patent: 4544212 (1985-10-01), Parzefall et al.
patent: 4705491 (1987-11-01), Andersson
Buhlmaier Fritz
Schetter Martin
Wright Dirk
Zahnradfabrik Friedrichshafen AG
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