Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2000-06-12
2001-10-16
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06301984
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a gear shifting device for a multi-ratio gear-changing transmission.
The problem on which this invention is based is to provide a gear shifting device which makes variable synchronizing times and short gear shifting times possible.
The problem is solved with a gear shifting device with the disclosed of claim
1
.
SUMMARY OF THE INVENTION
For each auxiliary unit of the gear-changing transmission, it is proposed that the unit be comprised of valves, shift cylinders, pistons and gear-shifting elements. Pulsed 2/2-way valves are used as release valves. At the same time, a displacement measuring device is used which indicates the actual position of the piston in relation to the shift cylinder.
When engaging the gear wheels in a torque-transmitting connection, it is possible to adapt shift force with the shift time. The adaptation preferably consists of the valves being loaded at a higher frequency when engaging the connection than when disengaging.
In another advantageous development, the pulse frequency of the 2/2-way valves provided when shifting gear on level ground is different from the pulse frequency when shifting gear on non-level ground, i.e. on uphill and downhill gradients. The pulse frequency when shifting gear on level ground is advantageously lower than on a non-level road.
In another advantageous development, the pulsed valve is operated with a voltage which amounts to a multiple of the standard voltage.
The displacement measuring device is preferably situated within the shift cylinder, but it can also be provided in a position outside the shift cylinder where it is connected with the movable part of the unit.
In another advantageous development, the piston of the auxiliary unit is placed upon a piston rod upon which it is axially movable. Upon the piston rod is provided the pistons of the gear shift units of several auxiliary units without hindering each other. The units are preferably disposed in one row for the auxiliary unit concerned.
In another advantageous development, several gear shift units, of which each gear shift unit belongs to an auxiliary unit, are comprised in one part. The part can be assembled separately from the transmission and then adapted and attached to the transmission as a unit. This also makes separate production possible, and testing of a complete gear shifting device independent of the transmission type involved.
In another advantageous development, the shift units have stops which dampen the impact of the piston on the edges of the shift cylinders. The stops can be provided within the shift cylinder or also outside on a part of the shift units connected with the piston.
Contrary to already known gear shifting devices, this whole gear shifting device sits in the immediate proximity of the auxiliary unit. An auxiliary unit is preferably formed of two gear wheels which are disposed side by side in the transmission and can be alternately engaged in the torque transmission. An auxiliary unit, however, can also consist of only one gear wheel engageable in the torque transmission when, e.g. two opposite gear wheels do not have to be engaged when shifting gear to a reverse gear ratio.
By virtue of a compact unit arrangement, it is also possible to eliminate connecting elements between gear shift elements, preferably formed of shift forks or shift levers, and the shift cylinders and shift pistons. As already mentioned, in such connecting elements shift rods are essentially made of steel which to a great extent contributes to the total weight of the transmission. The reaction times between a command to trigger a gear shift and the movement of the shift element is clearly abbreviated by the elimination of the bulky shift rods to be moved.
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Davis & Bujold P.L.L.C.
Wright Dirk
ZF Friedrichshafen AG
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