192 clutches and power-stop control – Clutches – Progressive engagement
Reexamination Certificate
1999-12-29
2001-07-31
Marmor, Charles A (Department: 3681)
192 clutches and power-stop control
Clutches
Progressive engagement
C192S053330, C192S11400R, C074S339000
Reexamination Certificate
active
06267215
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a clutch.
In selector gears which are shifted subject to interruption of traction force, i.e. one input shaft is separated from a prime mover by a clutch during the shifting operation, the desired gear can be engaged with a clutch of the above described type by slipping the selector teeth of a sliding sleeve into clutch teeth of a clutch body which is secured to a transmission element to be engaged such as a gearwheel or transmission housing. When engaged, the torque is transmitted from one gear element to another gear element, such as a gear wheel or shaft via the clutch body, the clutch teeth, the selector teeth, the sliding sleeve and the sleeve guide, or supported on the transmission housing. The gear engaged determines the reduction ratio and thus the rotational speed ratio between the input shaft and output shaft of the transmission. The transmission elements not engaged, e.g. the gear wheels of the remaining gears that rotate freely and are permanently engaged, rotate at a differential rotational speed corresponding to their ratio in relation to the transmission elements engaged. When shifting from one gear to another, the parts to be engaged have to be brought during the shifting operation to an almost equal rotational speed before the selector teeth of the sliding sleeve can mesh in the clutch teeth of the clutch body to be shifted.
A synchronizer mechanism serves this purpose. Essentially it consists of friction surfaces, such as a friction cone on the clutch body and friction surfaces such as a counter cone on a synchronizing ring, which in addition, has locking teeth. The synchronizing ring revolves with the sliding sleeve, but can rotate relative to it around a limited rotation angle between two stops in order that a locking device, such as locking teeth, is brought to locking position on the synchronizing ring.
If the sleeve is moved in the direction of the clutch body to be engaged, the synchronizing ring with its counter cone is pressed, via resilient detent means, against the friction cone of the clutch body. At the same time, the synchronizing ring turns relative to the sleeve so that frontside inclined surfaces of the selector teeth hit on corresponding locking surfaces of the locking teeth. Thereby an axial force is exerted on the synchronizing ring and the friction surfaces. The selector force simultaneously produces, via the inclined surfaces, a restoring force on the synchronizing ring. The force exceeds, during synchronous speed of the parts, the peripheral force acting on the friction surfaces and brings the synchronizing ring to a central position in which the sleeve can be cut through.
EP 0 184 077B1 has made known such selector clutches in particular for transmissions in countershaft design. The sliding sleeve is here movably disposed upon an inner sleeve carrier and the synchronizing rings are rotatably axially guided opposite the sleeve carrier around a rotation angle limited by stops. In addition, tangential springs are disposed between the sleeve carrier and the synchronizer ring in a manner such as to press both parts against their stops into neutral position contrary to the direction of motion.
DE 34 44 562 has disclosed a clutch for a planetary step which has synchronizing rings without locking teeth. The synchronizing rings mesh with engaging gears almost over the whole axial extent in the selector teeth of the sliding sleeve without allowing a limited angle of rotation.
The problem on which the invention is based is to make possible in clutches, a locking synchronization even when the sliding sleeve is guided on its external periphery and is very narrow.
SUMMARY OF THE INVENTION
According to the invention, the synchronizing rings mesh with cams in grooves of the sliding sleeve and this with a clearance such as to allow a limited rotation angle between the synchronizing rings and the sliding sleeve in order that locking teeth can be brought to a locking position on the synchronizing rings. In order that in a shift position the sliding sleeve, especially when it is too narrow, does not become disengaged with the cams of the other synchronizing ring, a few of the cams conveniently evenly distributed on the periphery are lengthened toward the other synchronizing ring and reach into the area of the other synchronizing ring over the gap between the synchronizing rings.
The cams of the two synchronizing rings conveniently mesh in equal grooves of the sliding sleeve, the cams of one synchronizing ring being lengthened by the same amount as the cams of the other synchronizing ring are shortened.
There is also the possibility that the cams, which mesh into a groove, do not lie obtusely opposed but are lengthened over part of their extension in peripheral direction and have bearing surfaces toward the lengthened part of the other cam. As this coupling is obtained the locking teeth of one synchronizing ring is moved to a locking position as soon as the locking teeth of the other synchronizing ring leave the way clear when shifting. Thereby the sliding sleeve cannot be moved unhindered from one shift position to the other shifting position without hitting on the locking teeth of the corresponding synchronizing ring.
Since the coupling members are mechanically firmly connected with the synchronizing rings, no vibration or tension of the synchronizer device generates as is the case, e.g. in spring elements.
The synchronizing rings can be brought to locking position while the sliding sleeve axially acts upon them via detent elements, such as a ring spring, and their friction cone presses against a counter cone on the clutch body. Due to the friction force acting in peripheral direction, the synchronizing ring is turned around the limited rotation angle so that the further shift stoke of the sliding sleeve is blocked by the locking teeth up to the synchronous rotational speed of the transmission parts to be coupled. The ring spring is designed axially very narrow so that the lengthened cams have only a small gap to bridge.
According to another development of the invention, the synchronizing rings are retained in locking position up to the end of the synchronization by tangential springs which act between the cams of the synchronizing rings or between the cams of the synchronizing rings and the groves of the sliding sleeve. Hereby the ring spring can be eliminated and the intermediate space between the synchronizing rings is reduced to a minimum. Besides, the synchronizing ring has to be turned only in one direction so that half a torsion angle results. Accordingly, the locking teeth have to be inclined only on one side and the teeth can be reinforced.
In the specification and in the claims, numerous features are shown and described related to each other. The expert will conveniently regard the combined features also separately, according to the problems to be solved, and make with them logical added combinations.
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Bader Josef
Buri Gerhard
Renner Stefan
Davis & Bujold P.L.L.C.
Marmor Charles A
Rodriguez Saul
ZF Friedrichshafen AG
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