TRANSMISSION AND VARIABLE RADIALLY EXPANDING SPRING CLUTCH ASSEMBLY

• US 20090064810A1
• Filed: 09/11/2007
• Published: 03/12/2009
• Est. Priority Date: 09/11/2007
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Agan, Kevin S., Norona, Joao, Bodine, Thomas J., Plato, Barry E.
• Granted Patent: US 7,793,560 B2
• Time in Patent Office: Days
• US Class Current: 74/333
• CPC Class Codes: F16D 43/208 moving radially between engagement and disengagement
• CPC Class Codes: F16D 7/002 the torque being transmitted and limited by yielding of an elastomeric race
• CPC Class Codes: F16D 7/10 moving radially between engagement and disengagement
• CPC Class Codes: F16H 3/32 and an additional shaft
• CPC Class Codes: F16H 35/10 Arrangements or devices for absorbing overload or preventing damage by overload for screw mechanisms F16H25/2021
• CPC Class Codes: Y10T 74/19242 Combined gear and clutch
• CPC Class Codes: Y10T 74/19274 torque responsive
• CPC Class Codes: Y10T 74/19358 Laterally slidable gears

Abstract

A transmission generally includes a shaft member having a continuous cylindrical surface portion longitudinally disposed next to a cylindrical outer surface portion interrupted by longitudinal grooves. A first gear assembly has a first clutch spring that holds a first set of rolling members between lobes that extend from a first output gear. A second gear assembly has a second clutch spring that holds a second set of rolling members between lobes that extend from a second output gear. The first gear assembly and the second gear assembly are configured to move longitudinally along the shaft member to a position where at least one of the first gear assembly and the second gear assembly is engaged for rotation with the shaft member when a value of torque at the shaft member is below a torque threshold value.

Claims

1. A transmission comprising:

a shaft member having a continuous cylindrical surface portion longitudinally disposed next to a cylindrical outer surface portion interrupted by longitudinal grooves;

a first gear assembly having a first clutch spring that holds a first set of rolling members between lobes that extend from a first output gear; and

a second gear assembly having a second clutch spring that holds a second set of rolling members between lobes that extend from a second output gear,

wherein said first gear assembly and said second gear assembly are configured to move longitudinally along said shaft member to a position where at least one of said first gear assembly and said second gear assembly is engaged for rotation with said shaft member when a value of torque at said shaft member is below a torque threshold value.

2. The transmission of claim 1, wherein said torque threshold value is at least based on an angle between a surface of one of said longitudinal grooves and a surface of one of said lobes of said first gear member between which a rolling member is disposed such that when a value of said angle decreases, said torque threshold value increases.

3. The transmission of claim 1, wherein said longitudinal grooves define a curvature that varies longitudinally along said shaft member.

4. The transmission of claim 1, wherein said first clutch spring and said second clutch spring have different spring constants.

5. The transmission of claim 1, wherein said first clutch spring includes helical coils that form a helical spring and wherein each of said helical coils contacts a successive coil.

6. The transmission of claim 1, wherein said first clutch spring includes helical coils that form a helical spring and wherein each of said coils is spaced apart from each other.

7. The transmission of claim 6, wherein an end of said first clutch spring is configured to contact a successive coil of said helical coils.

8. A transmission comprising:

an output shaft driven by a motor that is selectively energized by a trigger assembly that extends from a housing containing said motor;

a radially expanding spring clutch assembly including a shaft member connected to said output shaft, said shaft member directs torque to a gear member in a drive condition and when a value of torque surpasses a threshold value said shaft member directs a reduced torque to said gear member in a clutch out condition; and

a spindle shaft having a high speed gear and a low speed gear that move together longitudinally along said spindle shaft between a high speed condition and a low speed condition, wherein said clutch shaft is generally parallel to said spindle shaft,

wherein said high speed condition at least defines said high speed gear engaged to said spindle shaft and driven by a gear on said shaft member, said low speed gear engaged with said gear member but said low speed gear is free to rotate around said spindle shaft and

wherein said low speed condition at least defines said high speed gear engaged with said gear on said clutch shaft but free to rotate around said spindle shaft, said low speed gear driven by said gear member and engaged to said spindle shaft.

9. The transmission of claim 8, further comprising rolling members held against said shaft member by a clutch spring, said shaft member including an outer cylindrical surface interrupted by longitudinal grooves in which said rolling members are disposed when said radially expanding spring clutch assembly is in said drive condition, said rolling members move from said longitudinal grooves to said outer cylindrical surface when said radially expanding spring clutch assembly is in said clutch out condition.

10. The transmission of claim 9, further comprising lobes that extend from said gear member, said lobes disposed between said rolling members, wherein said threshold value of torque is at least based on an angle between a wall of one of said longitudinal grooves and a surface of one of said lobes between which one of said rolling members is disposed such that when a value of said angle decreases, said threshold value of torque increases.

11. The transmission of claim 8, further comprising an intermediate shaft having a gear that meshes with a gear on said output shaft and a gear on said intermediate shaft that meshes with a gear on said shaft member of said radially expanding spring clutch assembly, wherein said gear on said intermediate shaft that meshes with said gear on said output shaft establishes a first reduction mesh and said gear on said intermediate shaft that meshes with said gear on said shaft member establishes a second reduction mesh and wherein said spindle shaft, said shaft member, said intermediate shaft and said output shaft are generally parallel.

12. The transmission of claim 8, wherein a portion of said longitudinal grooves has a curvature that defines at least one of a plane, a v-shape, a radius, a ramp and one or more combinations thereof.

13. The transmission of claim 8, wherein said high speed gear is partially engaged with said gear on said clutch shaft when the transmission is in said low speed condition.

14. The transmission of claim 9, wherein said clutch spring includes helical coils that form a helical spring and wherein each of said helical coils contacts a successive coil.

15. The transmission of claim 9, wherein said clutch spring includes helical coils that form a helical spring and wherein each of said coils is spaced apart from each other.

16. The transmission of claim 9, wherein said clutch spring is configured with a substantially flat cross-section and said clutch spring continually wraps around a longitudinal axis of said shaft member such that portions of said clutch spring are spaced apart from said longitudinal axis at an increasing radial distance from said longitudinal axis.

17. The transmission of claim 9, wherein said clutch spring includes a plurality of individual helical clutch springs arranged longitudinally along said shaft member.

18. A transmission comprising:

a shaft member having a cylindrical outer surface in which longitudinal grooves are formed;

rolling members disposed in said longitudinal grooves;

a gear member having lobes;

said lobes disposed between said rolling members and over said shaft member;

a clutch spring that at least partially encircles said rolling members and said lobes, said clutch spring having a reduced torque condition that at least defines said clutch spring stretching to accommodate said rolling members leaving said longitudinal grooves and moving to said outer cylindrical surface such that said clutch spring forms a generally elliptical shape in said reduced torque condition.

19. The transmission of claim 18, wherein said clutch spring of the clutch moves from a drive condition to said reduced torque condition when a value of torque surpasses a threshold value, wherein said threshold value is at least based on an angle between a surface of one of said longitudinal grooves and a surface of one of said lobes between which one of said rolling members is disposed and wherein when a value of said angle decreases, said torque threshold value increases.

20. The transmission of claim 18, wherein at least two of said longitudinal grooves form are each substantially flat so as to be generally parallel to one another.

21. The transmission of claim 18, wherein a portion of said longitudinal grooves has a curvature that defines at least one of a plane, a v-shape, a radius, a ramp and one or more combinations thereof.

22. The transmission of claim 18, wherein said clutch spring is an annular unitary sleeve around said rolling members and said lobes.

23. The transmission of claim 18, wherein said clutch spring includes helical coils that form a helical spring and wherein each of said helical coils contacts a successive coil.

24. The transmission of claim 18, wherein said clutch spring includes helical coils that form a helical spring and wherein each of said coils is spaced apart from each other.