US 7,770,480 B2Granted

Transmission system

AssigneeZeroshift Limited

InventorWilliam Wesley Martin

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Abstract

A transmission system including first and second rotatable shafts, and means for transferring drive from one of the shafts to the other shaft including first and second gear wheels each rotatably mounted on the first shaft and having drive formations formed thereon, a selector assembly for selectively transmitting torque between the first shaft and the first gear wheel and between the first shaft and the second gear wheel, wherein the selector assembly includes an actuator assembly and first and second sets of engagement members that are moveable into and out of engagement with the first and second gear wheels independently of each other, said selector assembly being arranged such that when a driving force is transmitted, one of the first and second sets of engagement members drivingly engages the engaged gearwheel, and the other set of engagement members is then in an unloaded condition, wherein the actuator assembly is arranged to move the unloaded set of engagement members into driving engagement with the unengaged gear wheel to effect a gear change.

Claims31

Dependent claims

A transmission system comprising first and second rotatable shafts, said first shaft having a longitudinal axis, and means for transferring drive from one of the shafts to the other shaft comprising first and second gear wheels each rotatably mounted on the first shall and having drive formations formed thereon, a selector assembly for selectively transmitting torque between the first shaft and the first gear wheel and between the first shaft and the second gear wheel, wherein the selector assembly comprises an actuator assembly and first and second sets of engagement members, wherein each engagement member includes a first engagement face for engaging the first gear wheel, a second engagement face for engaging the second gear wheel, and a body that is substantially rigid such that the first and second engagement faces are arranged in a fixed relationship to one another, said actuator assembly including a shift fork assembly arranged to move each of the first and second sets of engagement members in first and second directions along the longitudinal axis of the first shaft into and out of engagement with the first and second gear wheels independently of each other, the arrangement being such that when one of the first and second gear wheels is selected by the first and second sets of engagement members backlash between the first and second sets of engagement members and the drive formations when moving between acceleration and deceleration is less than or equal to four degrees, and the transmission being further arranged such that when the first gear is selected by the first and second sets of engagement members and a driving force is transmitted the second set of engagement members drivingly engages the selected first gear wheel, and the first set of engagement members is then in an unloaded condition, wherein the shift fork assembly is arranged to move the unloaded first set of engagement members into driving engagement with the second gear wheel to effect a gear change.

A method for performing a decelerating downshift in a transmission system, said method including:

providing a transmission system having first and second rotatable shafts, said first shaft having a longitudinal axis;
providing first and second gear trains for transferring drive from one of the shafts to the other shaft, the first gear train including a first gear wheel rotatably mounted on the first shaft and the second gear train includes a second ear wheel rotatably mounted on the first shaft said first and second gear wheels having drive formation formed thereon and said second year wheel being part of a higher gear than the first gear wheel;
selectively transmitting torque between the second gear wheel and the first shaft via a selector assembly including an actuator assembly having a shift fork assembly, and first and second sets of engagement members by
engaging the second gear wheel with the first set of engagement members such that each of the engagement members in the first set engages the second gear wheel with a first engagement face, and by
engaging the second gear wheel with the second set of engagement members such that each of the engagement members in the second set engages the second gear wheel with a first engagement face, and such that backlash between the first and second sets of engagement members and the drive formations when moving between acceleration and deceleration is less than or equal to four degrees, wherein each of the engagement members includes a body that is substantially rigid such that the first and second engagement faces are arranged in a fixed relationship to one another;
and
starting from a position wherein the second set of engagement members drivingly engages the second gear wheel and the first set of engagement members is in an unloaded condition with respect to the second gear wheel, initially moving the unloaded first set of engagement members along the longitudinal axis of the first shaft by action of the fork assembly into engagement with the first gear wheel such that each of the engagement members in the first set engages the second gear wheel with a second engagement face, thereby transmitting torque between the first shaft and the first gear wheel to effect the gear change.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/555,728Filed 7 May 2004
Priority: GB 0310482.57 May 2003
Published: US 2006/0207362 A121 Sep 2006
Granted: 10 Aug 2010
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

F16D 23/02
Details of mechanically-actuated clutches not specific for one distinct type: arrangements for synchronisation, also for power-operated clutches
F16H 63/30
Final output mechanisms therefor; Actuating means for the final output mechanisms: constructional features of the final output mechanisms
F16D 11/10
Actuated by moving a non-rotating part axially: with clutching members movable only axially
F16D 21/04
For interconnecting three or more shafts or other transmission members in different ways: with a shaft carrying a number of rotatable transmission…