Transmission shift rail position sensor

• US 8,258,779 B2
• Filed: 11/26/2008
• Issued: 09/04/2012
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Wenzel, Gary Herman, DeFord, Nathan Paul
• Primary Examiner(s): Patidar, Jay
• Assistant Examiner(s): Schindler, David M.
• Application Number:
  US12/323,876
• Publication Number:
  US 20100127693A1
• Time in Patent Office: 1,378 Days
• Field of Search: 324/207.24, 324/207.2
• US Class Current: 324/207.24
• CPC Class Codes: F16H 2063/3079 Shift rod assembly, e.g. supporting, assembly or manufacturing of shift rails or rods; Special details thereof
• CPC Class Codes: F16H 59/70 dependent on the ratio established
• CPC Class Codes: F16H 63/30 Constructional features of the final output mechanisms

Abstract

The invention relates to a shift rail position sensing system. There is a need for a rapid and accurate shift rail position sensing system. In a transmission shift mechanism shifts are performed by axially moving a shift rail which is slidable in a rail bore in a housing. A rail position sensing system includes a groove formed in the shift rail and a Hall effect sensor. The groove includes a curved bottom surface, a first ramp surface extending from one side of the bottom surface to an outer peripheral surface of the shift rail, and a second ramp surface extending from a second side of the bottom surface to an outer peripheral surface of the shift rail. The Hall effect sensor has a sensor shaft with an axis normal to an axis of the shift rail. The sensor shaft has a sensing tip which adjacent to and spaced apart from the groove, so that the Hall effect sensor is sensitive an entire range of positions of the shift rail.

Claims

1. A rail position sensing system for sensing a position of shift rail which is slidable in a rail bore in a housing, the rail position sensing system, comprising:

a groove formed in the shift rail, the groove including a curved bottom surface, a first ramp surface extending from one side of the bottom surface to an outer peripheral surface of the shift rail, and a second ramp surface extending from a second side of the bottom surface to an outer peripheral surface of the shift rail;

the housing including a sensor bore, the sensor bore having an axis which intersects the rail;

a sensor housing mounted in the sensor bore, the sensor housing having an end facing towards the shift rail and spaced apart therefrom;

a magnet mounted inside the sensor housing near said end, the magnet generating a magnetic field, a portion of the rail which includes the groove extending into the magnetic field, movement of the rail producing changes in said magnetic field; and

a Hall effect sensor mounted inside the sensor housing near said end so that the Hall effect sensor detects changes in said magnetic field through a range of positions of the shift rail.

2. The rail position sensing system of claim 1, wherein:

the bottom surface is curved and concave in a direction facing the sensor.

3. The rail position sensing system of claim 1, wherein:

the bottom surface and the ramp surfaces are formed by a milling operation.

4. The rail position sensing system of claim 1, wherein:

the housing includes a chamber;

a shift fork is attached to the shift rail within said chamber; and

the sensor bore intersects with said chamber.