192 clutches and power-stop control – Clutches – Progressive engagement
Reexamination Certificate
2001-08-24
2003-07-08
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Progressive engagement
C074S339000, C192S053320
Reexamination Certificate
active
06588563
ABSTRACT:
BACKGROUND
The invention concerns a synchronizing apparatus for a manual shift transmission with:
a stationary, synchronizer body possessing torsional strength and circumferentially encompassing a gear shaft,
a movable sleeve on the synchronizer body, slidable along the longitudinal axis of the gear shaft,
at least one shift gear (
16
), rotatably placed on the gear shaft and which can be coupled to the synchronizer body (
13
) by the moveable sleeve (
14
), which gear is provided with a clutch body (
17
) or with a clutch gearing, and can be joined to the synchronizer body (
13
) by the clutch body or the clutch gearing,
at least one friction element connected to the shift gear
and at least one outer synchronizer ring having torsional strength connected to the synchronizer body,
wherein the outer synchronizer ring comprises essentially a conical body,
with that end piece thereof, of the greater diameter, being proximal to the shift gear, and that end piece thereof, of the smaller diameter, being proximal to the synchronizer body,
which is provided on its outer surface with a gear ring directed radially outward,
and the inner surface of which is designed as a friction surface which coacts with a friction element.
A synchronizing apparatus of this general type is described by EP 0 717 212A1. In this synchronizer apparatus, the friction element is formed by a conically designed friction ring with friction surfaces provided on both its inner and outer surfaces. These friction elements are also designated as an interposed ring and mesh with engaging cams, which project from its greater diameter end, matching with counter recesses of a clutch body. The friction surface on the outer exposed surface remains, during the synchronizing process, in a friction-locked connection with a corresponding friction surface on the outer synchronizer ring. At the same time, a friction surface, placed on the inner surface of the interposed ring, enters into a like friction connection with a friction surface of an inner synchronizer ring. The outer synchronizer ring is in a form-fit connection with the synchronizer body and engages with cams—which project radially inwardly from the lesser diameter cone end—matching recesses in the inner synchronizer ring. The inner synchronizer ring is thus, by means of the outer synchronizer ring, again in form-fit connection with the synchronizer body.
An improved ability for clutches in motor vehicle manual shift transmissions to carry greater stresses places continually growing demands on the components of the transmission. Corresponding with the greater load carrying ability of these clutches, the inertial moments to be braked in the transmission by the synchronizer rings also increase as the synchronizing proceeds. The required greater frictional forces to be produced, are generally brought about by greater frictional areas, that is, increasing the size of frictional surface pairs.
Also, as a rule, the diameter of the rings, i.e. the active width of the frictional surfaces, is increased, or, alternately, multiple synchronizing apparatuses are installed, that is, a plurality of sequential, interposed synchronizer rings are added. The entire synchronizing apparatus is thus larger, heavier and requires more space in the transmission.
Correlated to the demand for greater load capacities of synchronizing apparatuses, is a requirement that these apparatuses be of low weight and occupy a small installation space. Thus, in the design of modem synchronizing, a contradiction is created, between requirements for a higher friction capacity of synchronizing units and for their construction, sparing of both weight and installation space. Known solutions to this problem, in accord with the present state of the technology, are to be found in that the synchronizing rings are placed partially inside the allotted construction space of both the synchronizer body and the slide sleeve, and that one or more of the employed synchronizer rings is made of thin-walled, deep-drawn sheet metal.
The above references as to the state of the technology describe an arrangement, in which a deep-drawn outer synchronizer ring, a thin-walled interposed ring, and relatively massively built synchronizer ring are sequentially placed together. Theoretically, the width of this synchronizer ring arrangement would be designed only to the width of the breadth required for the friction capacity. From a practical standpoint, space requirements of elements for form-fit connection of the rings, along with their connection construction, such as matched catch and recess union, have yet to be given serious consideration.
The axial length of a synchronizing apparatus is essentially determined by the construction and the arrangement of such catches. As far as the outside width of the above embodiment in accord with the state of the technology is concerned, radially inward projecting, engaging catches of the inner synchronizer ring work disadvantageously counter to the length. Since such a synchronizer ring arrangement in a synchronizing apparatus, as a rule, is carried out twice, that is, left and right of the transverse middle plane of the synchronizer body, the required occupation of space is not a trivial matter. Sufficient axial installation space, as a rule, is available for a connection of friction rings by means of catches to the gear rings. The recesses necessary for this can be made in the convenient thick wall structure of the clutch body or the gear ring.
The outside width of a synchronizer and the weight, with which a synchronizer ring arrangement can be fitted into the synchronizer body, is essentially dependent, on how the shape-fit between the friction ring and the synchronizer body is designed. Of particular difficulty in this matter is the shaping of non-machined outer synchronizer rings, since here, besides the elements for the form-fit, also a key and detent element for a locking element of the synchronizing apparatus is to be provided and the rules of drawing mold release have to be observed, where non-machined manufacture is intended.
Particular attention is also to be given to the construction of the outer synchronizer ring. The shape of the generic type of an outer synchronizer ring is described in DE 35 19 811 C2. The axial extent of this ring is governed by the necessary thickness of its frictional surfaces. The shape-fit to neighboring components is effected by a recessed outer gear ring and by matching detents. The detents are formed from lugs, which, by being bent by other projecting tongues to the surface of the synchronizer body lie symmetrically directed. Projecting outward from that end of the ring on which the larger diameter of the conical shape is found, the aforesaid lugs point, with their free ends in the direction of the smaller diameter end of the conical ring. These lugs, during the manufacturing process and after the drawing, are stamped out of the like rim of the bowl-like object together with the gear ring and are subsequently bent. Form fitting connections, extending from the end with the smaller diameter, which match synchronizer rings of this type, can only be made by lugs, which longitudinally extend over the entire axial length of the synchronizer ring. The longer a lug is, the much more difficult it will be to exactly align the same in its proper position and place. The manufacturing demands in labor and time, and hence in fabrication costs, are increased, for instance by additional calibration. The width of such a detent acts disadvantageously to the precision of such a detent. The wider, and also the thicker the lug is made, just so much more difficult is its exact shaping.
High capacity synchronizing apparatuses encounter high torques, and very frequently, abrupt momentum peaks occur. Any lug construction must transmit such moments and peaks. The cross-sections of said lugs are correspondingly subjected to high shear and bending stresses. The lugs, on this account, must be thick in design and be made with high strength materials. Technological limits, as already
Martin Reiner
Sarrach Roland
Schwuger Josef
Sinner Rudolf
Abdelnour Dennis
Bonck Rodney H.
INA-Schaeffler KG
Volpe and Koenig P.C.
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