Shift drum assembly of a transmission

Patent metadata

Field	Value
Publication number	US-10041590-B2
Application number	US-201615336083-A
Country	US
Kind code	B2
Filing date	Oct 27, 2016
Priority date	May 20, 2013
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A shift-by-wire transmission system is provided. The system includes a gearbox that is configured and arranged to receive a rotational input and provide a select rotational output. The gearbox includes a plurality of gear assemblies that are operationally coupled together to provide the select rotational output from the rotational input. A shift assembly is operationally coupled to the plurality of gear assemblies of the gearbox to selectively change gearing of gearbox. An electric motor is operationally coupled to the shift assembly to activate the shift assembly to selectively change the gearing of the gearbox. A manual shift override is employed that is coupled between the shift assembly and the electric motor. The manual shift override is configured and arranged to manually disconnect the electric motor from the shift assembly and activate the shift assembly.

First claim

The invention claimed is:

1. A shift drum assembly for a gear box of a transmission, the shift drum assembly including:
a shift drum housing having at least one groove guide with a select profile that is configured to receive at least one shift fork positioning pin of a shift fork, the shift drum housing further having a window, the window including a first side wall and a second side wall;
a shift cam rotationally coupled to the shift drum, the shift cam having a shift cam tab positioned within the window of the shift drum, the shift cam tab configured to selectively move between the first side wall and the second side wall of the window; and
a bias member configured to bias the shift cam in relation to the shift drum to create a preload force used at least in part to complete a shift when a blocked shift condition of the gear box is encountered.

2. The shift drum assembly of claim 1 , further comprising:
the shift drum having a shift drum post, the shift cam received around the shift drum post.

3. The shift drum assembly of claim 2 , further comprising:
the bias member received around the shift drum post;
the shift drum post having a spring holding aperture;
the shift cam having a spring holding slot; and
a first end of the bias member received with the spring holding slot of the shift cam and a second end of the bias member received within the spring holding aperture of the shift drum post.

4. The shift drum assembly of claim 1 , further comprising:
the at least one groove guide formed by at least one portion of the shift cam;
the at least one portion of the groove guide formed by the shift cam having a ramp section; and
the shift cam tab of the shift cam configured to be initially biased against the first side wall of the window of the shift drum housing during the blocked shift condition, wherein rotation of the shift drum housing in a first direction counters a bias force of the bias member via the at least one shift fork positioning pin of the shift fork engaging the ramp section of the at least one groove guide of the shift cam allowing the shift cam tab of the shift cam to move towards the second side wall of the window of the shift drum therein creating additional torsion preload while allowing the shift drum housing to reach a target angular position even though the shift cam and the shift fork positioning pin have not moved thereby creating a state of preload.

5. The shift drum assembly of claim 4 , further wherein movement of the shift fork positioning pin up the ramp section of the shift cam is configured to cause the shift drum assembly to complete the shift.

6. The shift drum assembly of claim 5 , wherein movement of the shift fork positioning pin up the ramp section of the shift cam is caused by at least one of rotation of a wheel operationally coupled to the at least one shift fork positioning pin and rotation of an input shaft to the gear box that is operationally coupled to the at least one shift fork positioning pin.

7. The shift drum assembly of claim 1 , wherein the shift cam tab of the shift cam is configured to engage the first side wall of the window of the shift drum housing during rotation of the shift drum housing in a second direction.

8. A transmission comprising:
a plurality of gearing assemblies operationally coupled together to provide a select rotational output from a rotational input of an input shaft to the transmission;
at least one shift fork configured and arranged to change gearing of the gearing assembly;
a shift drum housing forming at least a portion of at least one groove guide, the at least one groove guide having a select profile that includes a ramp section, the at least one groove guide configured and arranged to receive at least one shift fork positioning pin of the at least one shift fork, the shift drum housing further having a window, the window including a first side wall and a second side wall;
a shift cam rotationally coupled to the shift drum, the shift cam having a shift cam tab positioned within the window of the shift drum, the shift cam tab configured to selectively move between the first side wall and the second side wall of the window; and
a bias member configured to bias the shift cam in relation to the shift drum to create a preload force used at least in part to complete a shift when a blocked shift condition of a gear box of the transmission is encountered.

9. The transmission of claim 8 , further comprising:
the shift drum having a shift drum post, the shift cam received around the shift drum post.

10. The transmission of claim 8 , further comprising:
the bias member received around the shift drum post;
the shift drum post having a spring holding aperture;
the shift cam having a spring holding slot; and
a first end of the bias member received with the spring holding slot of the shift cam and a second end of the bias member received within the spring holding aperture of the shift drum post.

11. The transmission of claim 8 , further comprising:
the at least one groove guide formed by at least one portion of the shift cam;
the shift cam including the ramp section of the at least one groove guide; and
the shift cam tab of the shift cam configured to be initially biased against the first side wall of the window of the shift drum housing during the blocked shift condition, wherein rotation of the shift drum housing in a first direction counters a bias force of the bias member via the at least one shift fork positioning pin of the shift fork engaging the ramp section of the at least one groove guide of the shift cam allowing the shift cam tab of the shift cam to move towards the second side wall of the window of the shift drum therein creating additional torsion preload while allowing the shift drum housing to reach a target angular position even though the shift cam and the shift fork positioning pin have not moved thereby creating a state of preload.

12. The transmission of claim 11 , further wherein movement of the shift fork positioning pin up the ramp section of the shift cam is configured to cause the transmission to complete the shift.

13. The transmission of claim 11 , wherein movement of the shift fork positioning pin up the ramp section of the shift cam is caused by at least one of rotation of a wheel operationally coupled to the at least one shift fork positioning pin and rotation of the input shaft to the transmission that is operationally coupled to the at least one shift fork positioning pin.

14. The transmission of claim 8 , wherein the shift cam tab of the shift cam is configured to engage the first side wall of the window of the shift drum housing during rotation of the shift drum housing during a shift.

15. The transmission of claim 14 , wherein the shift cam tab of the shift cam remains engaged with the first side wall of the window when the shift drum housing rotates in a second direction.

16. A transmission system for a vehicle implementing a gearbox with shift dogs, the transmission system comprising:
an input shaft:
a plurality of gearing assemblies operationally coupled together to provide a select rotational output from a rotational input of the input shaft:
at least one shift fork configured and arranged change gearing of the gearing assembly;
a shift drum housing having a window;
a shift cam rotationally coupled to the shift drum and forming with the shift drum at least one groove guide with a select profile that is configured to receive at least one shift fork positioning pin of the at least one shift fork, the shift cam having a shift cam tab positioned within the window of t

Assignees

• Team Ind Inc

Inventors

• Maki Gregory L

Classifications

• Y10T74/19279

  Cam operated · CPC title

• F16H61/682 Primary

  with interruption of drive · CPC title

• F16H63/18

  the final actuating mechanism comprising cams · CPC title

• F16H63/48

  Signals to a parking brake {or parking lock; Control of parking locks or brakes being part of the transmission} · CPC title

• F16H63/3458

  with electric actuating means, e.g. shift by wire · CPC title