Dual reversed cone synchronizing clutch

A dual cone pin type synchronizing clutch for driveably connecting to a shaft gear wheels journalled on the shaft includes a hub splined to the shaft, a clutch sleeve connected to the hub through spline teeth that permit axial displacement of the sleeve into engagement with clutching teeth formed with the gear wheel. Each gear wheel carries a cone element engageable with a conical friction surface that is fixed to the gear wheels. A cone arm assembly carries cone members adapted to engage frictionally an intermediate cone member when the sleeve is displaced. The frictional contact between the cone elements, which engage before the clutching teeth engage, operate to synchronize the speed of the gear wheels to that of the synchronizer hub. The sleeve defines a space within which a detent spring is trapped and forced radially outward against the inner surface of the cone arm assembly, when the sleeve is displaced from the neutral position, or into a detent groove, when the clutch sleeve returns to the neutral position.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a cone-pin type blocking synchronizer for a 
multiple speed manual transmission More particularly, the invention 
pertains to such a synchronizer having multiple conical friction elements 
for synchronizing the speeds of a shaft and a gear wheel before clutch 
engagement. 
2. Description of the Prior Art 
Automotive manual transmissions currently use synchronizing clutches to 
make gear changes. These synchronizing clutches usually employ frictional 
engagement between the synchronizer and the gear to be engaged when the 
speeds of these components are asynchronous, the frictional connection 
continuing until synchronization occurs. After the speeds are made 
synchronous, the components are driveably connected through positive 
mechanical means. 
Usually the frictional engagement is made when a conical friction surface 
is forced by the vehicle operator into contact with a complimentary 
conical friction surface fixed to one of the gear wheels. The gear wheel 
is connected through the synchronizer to the shaft on which it is 
journalled after synchronization by moving spline teeth on the clutch 
sleeve into engagement with clutching teeth on the gear wheel. 
High torque capacity engines require large neutral clutches whose 
components, which have large polar moments of inertia, are fixed to the 
engine shaft and input shaft of the transmission. When gear shifts are 
made, the rotating inertia of these components requires that a large 
torque be applied to the gear wheel while its speed is synchronized with 
that of the output shaft or the countershaft of the transmission and 
before a mechanical connection is made by the synchronizing clutch. This 
inertial torque must be accomodated in the synchronizing clutch in a 
relatively small space provided between the gear wheels on the shaft to 
which the synchronizer driveably connects the gear wheels. Large vehicles, 
particularly heavily loaded trucks, tractors and the like, require that 
gear changes be made rapidly and with the least possible change in engine 
speed and vehicle speed in order to conserve the kinetic energy of the 
vehicle, particularly when climbing hills. The synchronizing clutches in 
the prior art require large friction surfaces, which require a large space 
for the synchronizer clutch in order to meet the torque capacity 
requirements of the clutch. In vehicles equipped with prior art 
synchronizers, the vehicle operator must apply a large force to the gear 
shift lever when making gear changes so that gear shifts are made rapidly. 
Alternatively, if less shifting force is applied, the period for gear 
engagement is protracted, and the kinetic energy of the vehicle is 
dissipated. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a synchronizing clutch having 
multiple conical surfaces for connecting a gear wheel to the synchronizer 
hub in order to transmit a large inertial torque through the synchronizer. 
It is another object of this invention to provide a synchronizing clutch 
having multiple friction surfaces and high torque capacity in a space 
whose radial dimension between the gear wheels is a minimum. 
In realizing these and other objectives, the synchronizing clutch of this 
invention includes a first cone member rotatably supported on a gear wheel 
and free to rotate relative to the gear wheel. A synchronizer hub, 
rotatably connected to a shaft, carries a synchronizer sleeve on spline 
teeth at its outer periphery and permits axial displacement of the sleeve 
into engagement with clutching teeth on the gear wheel while its 
engagement with the synchronizer hub is maintained. A cone arm assembly 
extends axially through a slotted web of the synchronizer sleeve and 
supports members having conical at each of its ends friction surfaces on 
their inner surfaces. The cone arm assembly is connected to each of the 
cone members that are supported rotatably on the gear wheels. An 
intermediate friction member driveably connected to each gear wheel is 
fitted between the outer and inner cone members. 
The clutch sleeve defines an annular space located between radially 
directed flanges into which space is fitted a detent spring, which is 
forced radially outward into contact with a recess on the inner surface of 
the cone arm assembly. The detent spring is maintained in position within 
the annular space and is carried by the clutch sleeve axially out of the 
detent recess when the clutch sleeve is moved from the neutral position 
toward the gear wheel while a gear change is being made. When the clutch 
sleeve is returned to the neutral position, the spring reseats within the 
detent recess and maintains the clutch sleeve in its neutral position. 
The clutch sleeve defines blocking surfaces that contact mating blocking 
surfaces on the cone arm assembly. As the clutch sleeve is moved axially 
by the vehicle operator during a gear change, the cone arm assembly is 
moved axially bringing the conical surfaces into contact with the mating 
friction surfaces on the intermediate cone member. This frictional 
engagement operates to synchronize the speeds of the gear wheel and the 
clutch hub before the sleeve is moved axially further into mechanical 
engagement with the clutching teeth on the gear wheel.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A shaft 10 of a manual transmission supports gear wheels 12, 14 journalled 
on its surface and the hub 16 of a synchronizing clutch rotatably 
connected by splines 18. The outer surface of the hub has multiple axially 
directed splined teeth 20 engaged by the internal spline teeth 22 of the 
synchronizer clutch sleeve 24, which is moveable axially with respect to 
the hub toward the gear wheels and is rotatably connected to the shaft 
through hub 16. Each gear wheel has clutching teeth 26, 28 located for 
engagement alternately by the internal spline teeth of the clutch sleeve 
when the sleeve is moved toward the gear wheels and while it remains 
engaged with the hub. 
The clutch sleeve defines an annular recess 30 located between a radially 
directed web 32 and a flange 34, wherein an annular, open ended wire 
spring 36 is fitted. The spring seats within a recess 38 on the inner 
surface of a cone arm assembly. Arm 40 moves toward the selected gear when 
the clutch sleeve is moved by the vehicle operator and causes spring 36 to 
move radially inward out of recess 38 and into contact with the inner 
surface 42 of the arm. When the sleeve is returned to the neutral position 
between the gear wheels, spring 36 moves resiliently, radially outward and 
reseats within recess 38, thereby providing a detent function. 
Each axial end of cone arm 40 carries a cone element 44, 46 adapted to 
engage an intermediate conical friction shoe 48, 50, which is connected to 
the associated gear wheel engagement by tabs 52, 54. The intermediate 
conical elements 48, 50 carry on their exterior and interior surfaces 
friction pads 56, 58. Journalled rotatably on a cylindrical surface of 
each gear wheel is an internal cone element 60, 62, which is rotatably 
connected by tabs 64, 66 to the end of cone arm 40. 
In operation, when an axially directed force is applied to the synchronizer 
sleeve 24 by movement of the shift fork under the control of the vehicle 
operator, a blocking surface on the cone arm assembly contacts a blocking 
surface on the clutch sleeve and moves the cone elements 44 or 46 into 
contact with the intermediate friction shoes 48 or 50, respectively. A 
force develops on the face of the friction shoe tending to force the shoe 
into contact with the outer surface of cone element 60 or 62. A friction 
force develops on the inner friction pad 58 as well as on the outer 
friction pad 56. The friction component of the normal force applied to the 
friction pads by the rotating conical elements operates to synchronize the 
speed of the gear wheel with the speed of the shaft. In this 
configuration, the torque applied to the gear wheel in order to 
synchronize its speed with that of the shaft is approximately twice the 
torque that could be developed with one frictional surface operating to 
develop the torque.