Machine element or mechanism – Gearing – Interchangeably locked
Patent
1994-04-20
1996-04-02
Wright, Dirk
Machine element or mechanism
Gearing
Interchangeably locked
F16H 6104
Patent
active
055030394
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a motor vehicle transmission, especially a multi-step synchronized transmission, according to the preamble of claim 1.
In a multi-step motor vehicle transmission existing at present, two successive or adjacent speeds are respectively associated with one gearshift set. By a first gear shift set consisting of, for instance, a gearshift sleeve with or without synchronization, gearshift levers or shifting dogs, etc., the first and the second speeds, for instance, are engaged and disengaged while a second gearshift set engages and disengages the third and fourth speeds, for instance, and possibly two other speeds can be shifted via a third gearshift set. If, in such a known transmission, the next higher or lower speed is engaged, an interruption of the traction force occurs during the shifting operation, at least at low speeds, since a speed adjustment of the countershaft must be effected via the synchronizing means of the next speed, for instance, for the upshift. When changing from the first to the second speed, the synchronizing means of the second speed must effect a braking of the corresponding gear and thus of the whole countershaft so as to make possible the engagement. As result of this, a relatively severe wear (high load) of the gearshift sets takes place, shortening the service life thereof. Besides, an increased synchronization period is needed whereby a long interruption of the traction force results due to the time interval between gearshifts which may originate in the control from the thrust operations during the gear-selection process and from dead periods. To prevent such severe wear, for instance, the synchronizing sets must be made relatively large.
The problem to be solved by the invention is to provide a motor vehicle transmission of the above mentioned kind which makes possible substantially improved gearshifting properties combined with longer duration, especially of the synchronizing means, and practical improvements.
This problem is solved by a motor vehicle transmission which, according to the invention, has the features of claim 1. The sub-claims contain other advantageous embodiments.
Accordingly, a novel gear arrangement is obtained, that is, the two speeds associated with respective gearshift sets are not successive speeds. Thus, for instance, speeds 1 and 3 are actuated by a first gearshift set and speeds 2 and 4 by a second gearshift set, etc. This affords the possibility, when changing speed for instance from the first to the second or from the second to the third, of utilizing the separate controllability of the gearshift devices for reducing the time interval between gearshifts, since adjacent speeds are actuated or shifted by different gearshift sets or gearshift devices.
It is advantageous for this that an actuating means, driven and controlled independently of the actuating means of the remaining gearshift sets, be associated with each gearshift set. For this purpose, any actuating means known per se having different energies such as hydraulic, pneumatic or electric devices can obviously be used. But in multi-step gearshift transmissions existing at present, the electric power supply existing in each vehicle is being increasingly used as source of energy, in addition the trend being toward the electronic control of the driving operations. Therefore, it is especially advantageous to use a mechanism controlled and actuated by electrical power such as an electromotor combined with an electronic control as an actuating means. For coverting the rotation movement, obtained by the electromotor and controlled in relation to the torque and direction of rotation, to a translatory gearshift movement any conveniently designed device which makes such conversion possible can be used. It is thus possible to use, for instance, a spatial cam transmission like threaded spindle or ball and socket threaded spindle combined with a corresponding nut or a rack and pinion device, etc. Said actuating means makes very precise control of the translatory rotary movements for the
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patent: 5105675 (1992-04-01), Langford et al.
patent: 5172602 (1992-12-01), Jurgens et al.
Bailly Gerhard
Gazyakan Unal
Wright Dirk
ZF Friedrichshafen AG
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