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FIELD OF INVENTION
This invention relates to an improved synchronizer for damage control of
synchronizer ring. The invention is particularly directed to improvement
in low speed synchronizer pack of the synchronizer.
BACKGROUND/PRIOR ART OF THE INVENTION
Vehicle is customarily available with synchronizer comprising a
synchronizer pack for each set of gears, which helps in gear shifting in
manual transmission. Said pack consists of a synchronizer hub (fig. 1)
fitted with a synchronizer ring (fig. 2) on its both sides wherein the hub
with rings is accommodated inside a sleeve (S) as shown in fig. 3. The
ring is having a number of slots (1, fig. 2) for housing key (2, fig. 3)
therein. The pack is mounted on a shaft and the hub of the pack is
fixedly placed on the shaft. While shifting the gears, the sleeve moves to
and fro alongwith the ring.
Specifically in diesel engines, due to their inherent design, drive-line
components including synchronizer are subjected to higher torsional
vibrations resulting in higher fatigue of the components. Vehicles driven
at higher RPM for longer durations in higher gears are occasionally
observed to have developed damage in Synchronizer Ring. Due to this
damage, Synchronizer Ring loses its functional characteristics to
synchronize, thereby making gear shifts difficult or sometimes impossible
in worst case.
Generally in the synchronizer rings of synchronizer pack meant for low
speed gear i.e. 1st and 2nd gear are observed to have undergone damage
(wear/indentation). The synchronizer pack of low speed gear is damaged
due to fluctuation caused by the engine. The fluctuation is due to
presence of clearance between the ring and hub leading to rotational and
radial movement of the ring.
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Due to clearance, side face of synchronizer key slot area undergoes
damage owing to low thrust contact area between synchronizer ring slot
thrust face and synchronizer keys. High torsional vibrations lead to
higher torsional stresses (T, fig. 3) on ring thrust area. With insufficient
contact (thrust) area, more thrust on the side surface of slot and
inherent misalignment of the ring (due to movement of ring radially),
damage occurs affecting gear shifting adversely.
Now, reference may be made to the following prior arts:
A prior art is directed to a support for a synchronizing ring for the
synchronization of gears, in which the stops for coupling to the clutch
are formed from lugs which are bonded integrally to the sprocket ring or
ring-shaped core.
US4698889: A new core for a synchronizing ring for gear
synchronization is produced using a punching and stamping method.
The lugs for coupling to the clutch are produced by stamping from the
material of the conical core.
Another prior art discloses a ring having a locking device i.e. safety lug,
provided for fixing the ring in an installation condition in a cylindrical
hollow chamber of a synchronous ring hub. The locking device is
integrally connected with a ring body and extends in a direction from a
toothed wheel surface of the ring body. A guide element is provided for
guiding an outer installation surface into the hollow chamber at the
locking device.
All of the above though related to synchronizer, however none of them is
suggesting a solution to the problem, for which invention of the Proposed
Application has been introduced.
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OBJECTS OF THE INVENTION
A primary object of the present invention is to propose an improved
synchronizer for damage control of synchronizer ring which overcomes
disadvantages associated with the known arts.
Another object of the present invention is to propose an improved
synchronizer for damage control of synchronizer ring which reduces the
effect of torsional vibration on synchronizer ring, thereby protecting the
ring from fatigue.
Further object of the present invention is to propose an improved
synchronizer for damage control of synchronizer ring, which helps to
improve functional life of synchronizer ring against the damage.
Yet another object of the present invention is to propose an improved
synchronizer for damage control of synchronizer ring which is reliable
and operates efficiently.
SUMMERY OF THE INVENTION
According to this invention, there is provided an improved synchronizer
pack of synchronizer comprising a synchronizer hub fitted with
synchronizer rings accommodated inside a sleeve, wherein the
synchronizer ring is integrally provided with a plurality of lugs on its
boss area for protection against damage due to engine torsional
vibration.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent
from the ensuing description when read in conjunction with the
accompanying drawings and wherein:
Fig. 1 shows: Synchronizer hub.
Fig. 2 shows: Synchronizer ring according to present invention.
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Fig. 3 shows: Synchronizer ring and key impact.
Fig.4 shows: Synchronizer ring according to present invention.
Fig.5 shows: Synchronizer ring boss area
Fig.6 shows: Lug with friction layer on the synchronizer ring in
accordance with present invention.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH
REFERENCE TO THE ACCOMPANYING DRAWINGS
The instant invention pertains to an improved synchronizer for damage
control of synchronizer ring. As already discussed, synchronizer hub
with a synchronizer ring on both sides is inserted inside a sleeve
constituting synchronizer pack, which is mounted on shaft for shifting of
gear in manual transmission. The ring as indicated in fig. 2 is well
known in the art, therefore further elaboration is not required for a
person skilled in the art.
The invention focuses on the improvement in the design of synchronizer
ring for protection against damage due to engine torsional vibration
(fluctuation).
Now, reference may be made to fig.4 and 5 in which the synchronizer
ring is integrally provided with a plurality of lugs (L) on its boss area (B).
Synchronizer ring boss area comprises cylindrical surface, which is
radially concentric with the hub inner guiding boss area (A, fig. 1). The
lugs constituting bulges protrude radially outwards from synchronizer
ring boss area. The lugs are preferably equally spaced along the ring boss
area in circumferential direction. In the exemplary embodiment of ring
according to present invention, there is provision of three lugs on the
ring. These lugs help in guiding synchronizer ring inside synchronizer
hub and maintains uniform thrust area at the time of impact between
synchronizer ring and key.
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Effects of above provision are as follows:-
- Improved thrust contact area between synchronizer ring and key,
which ensures uniform contact of all three slot side face thrust
contact area.
- Reduced severity of torsional impact between synchronizer ring
and key.
- Restricts radial movement of the synchronizer ring.
In order to reduce the overall torsional impact magnitude by reducing the
torsional acceleration of synchronizer ring due to engine torsional
vibrations i.e. to control rotational motion of the ring body along the hub
in circumferential direction, a provision is requested to be made, for
which reference may be made to fig. 6. The reduction of torsional
acceleration is achieved by coating outer surface of lugs.
The coat comprises friction layer (F) preferably made of carbon friction
material without restricting scope of the invention to the same. Other
friction materials readily apparent to person skilled in the art are
understood to be within ambit of the invention. Friction between
synchronizer ring's lug's outer surface and synchronizer hub inner
guiding boss area damps torsional acceleration resulting in drastic
reduction in the severity of torsional impact between synchronizer ring
and key.
According to another embodiment, synchronizer hub inner guiding boss
area may be provided with a friction layer as an alternative to said lug
friction layer. However, coating lug is highly efficient and cost effective
thereby rendering coating of synchronizer hub inner guiding boss region
unwarranted.
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Thus, with the above provisions, the.invention accomplishes reduction in
the misalignment between synchronizer ring and hub and induction of
hysteresis to dampen angular acceleration of synchronizer ring due to
engine torsional vibration.
Advantageous Features
- Prevention of damage to synchronizer ring owing to engine
torsional vibration.
- Improved thrust contact area between synchronizer ring and key,
thereby reducing torsional impact between synchronizer ring and
key.
- Reduction of the torsional impact by reducing the torsional
acceleration of ring.
- Reliable and efficient.
It is to be noted that the present invention is susceptible to
modifications, adaptations and changes by those skilled in the art. Such
variant embodiments employing the concepts and features of this
invention are intended to be within the scope of the present invention,
which is further set forth under the following claims:-

WE CLAIM:
1. An improved synchronizer pack of synchronizer comprising a
synchronizer hub fitted with synchronizer rings accommodated
inside a sleeve, wherein the synchronizer ring is integrally
provided with a plurality of lugs on its boss area for protection
against damage due to engine torsional vibration.
2. An improved synchronizer pack of synchronizer as claimed in
claim 1, wherein the lugs constituting bulges facing radially
outwards from synchronizer ring boss area.
3. An improved synchronizer pack of synchronizer as claimed in
claim 1 or 2, wherein the lugs are preferably equally spaced
along the circumferential direction of the synchronizer ring.
4. An improved synchronizer pack of synchronizer as claimed in
any of the preceding claims, wherein the lugs are covered with a
friction layer to reduce the torsional impact by decreasing the
torsional acceleration of the synchronizer ring.
5. An improved synchronizer pack of synchronizer as claimed in
any of the preceding claims is associated with the advantageous
features such as herein described.
6. An improved synchronizer pack of synchronizer substantially as
herein described with reference to the accompanying drawings.