US3677096A

US3677096A - Miniature indexing mechanism

Info

Publication number: US3677096A
Application number: US148781A
Authority: US
Inventors: Raymond G Hatman
Original assignee: GTE Sylvania Inc
Current assignee: GTE Sylvania Inc
Priority date: 1971-06-01
Filing date: 1971-06-01
Publication date: 1972-07-18
Anticipated expiration: 1989-07-18

Abstract

A miniature indexing mechanism employs a shaft of a first diameter having a drum of a second diameter, the second diameter being larger than the first. Two holes are located diametrically opposite each other in the walls of the drum. A hat shaped housing member includes a plurality of smaller holes circumferentially located along the inner wall thereof and has an internal diameter slightly larger than the drum section of the shaft such that the drum section is free to rotate within the wall of the housing member. Ball bearings are inserted in each of the two drum holes and are biased outwardly toward the inner walls of the housing member by a circular leaf spring. As the shaft is rotated, the bearings seat in the holes along the inner walls of the housing thus providing an indexing mechanism.

Description

United States Patent Hatman MINIATURE INDEXING MECHANISM Lewandowski et a1 ..74/527 X 14kg] i [45] July 18, 1972 Primary Examiner-Milton Kaufman Attomey-Norman J. O'Malley, Elmer J. Nealon and Robert T. Orner [57] ABSTRACT A miniature indexing mechanism employs a shafi of a first diameter having a drum of a second diameter, the second diameter being larger than the first. Two holes are located diametrically opposite each other in the walls of the drum. A hat shaped housing member includes a plurality of smaller holes circumferentially located along the inner wall thereof and has an internal diameter slightly larger than the drum section of the shaft such that the drum section is free to rotate within the wall of the housing member. Ball bearings are insorted in each of the two drum holes and are biased outwardly toward the inner walls of the housing member by a circular leaf spring. As the shaft is rotated, the bearings seat in the holes along the inner walls of the housing thus providing an indexing mechanism.

8 Clains, 4 Drawing Figures PATENTED JULI 81972.

INVENTOR.

RAYMOND 6. HARTMAN QZM 70 ATTORNEY MINIATURE INDEXING MECHANISM BACKGROUND OF THE INVENTION This invention relates to indexing mechanisms and in particular to a miniature indexing mechanism useful in a rotatable switching device in which discrete switch positions are desired.

In small portable electronic devices, such as a small handheld rescue radio employing a plurality of radio channels and functions, there is a requirement for a miniature switch which has discrete positions corresponding to each channel and/or function. Existing detents or indexing mechanisms are generally too large and bulky. For example, standard mechanisms have a ball retainer mounted on a rotating shaft, a plurality of indexing cams located in a housing surrounding the shaft and ball retainer. Helical springs exert force on the balls, seating them in detents within the housing. Separate shaft alignment bearings and load bearings are required to center the rotating shaft within the housing.

It would therefore be advantageous to have and it is one of the objects of this invention to provide a miniature detent mechanism employing a simple design for attaining shaft alignment and discrete shaft positions.

SUMMARY OF THE INVENTION An indexing mechanism according to the present invention includes a shaft having a first diameter and an open-ended drum section coaxial with the longitudinal axis of the remainder of the shaft. The drum section, having a larger diameter than the first diameter, includes an opening in the wall thereof. A housing member has a hollow cylindrically shaped interior with first and second openings in the respective ends thereof, the diameter of the first opening being slightly larger than the first diameter of the shaft and the diameter of the second opening being slightly larger than the diameter of the drum section. The hollow cylindrically shaped interior includes a plurality of indentations located circumferentially around the wall thereof, the size of each of the indentations being slightly less than the size of the opening in the wall of the drum section of the shaft.

The shaft is positioned within the housing member such that the drum section rotates within the hollow cylindrically shaped interior of the housing member. A bearing member is positioned in the opening in the wall of the drum section of the shaft and is forced into a certain one of the plurality of indentations in the interior of the housing member by a biasing means. As the shaft is rotated, the bearing member rides in and out the indentations in the housing member thus providing an indexing mechanism.

DESCRIPTION OF THE DRAWINGS The construction and operation of the detent mechanism will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view of an embodiment of the detent mechanism according to the invention;

FIG. 2 is a perspective view of a shaft employed in the embodiment of FIG. 1;

FIG. 3 is a perspective view of a housing member employed in the embodiment of FIG. 1; and

FIG. 4 is a perspective view of a spring employed in the embodiment of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION An indexing mechanism 10, a cross-sectional view of which is shown in FIG. 1, includes a shaft 12 (FIG. 2) having a first diameter D, and a hollow drum section 14 having a second diameter D,. Included in the wall of the drum 14 is a pair of openings 16 located diametrically opposite each other. The function of the openings 16 will be discussed hereinafter. Also included in the indexing mechanism is a hat shaped housing 18 having a cylindrically shaped inner wall 20 with first and second circular openings 22 and 24 in the ends thereof. The diameter of the first opening 22 is slightly larger than the first diameter D, of the shaft 12, and the diameter of the second opening 24 is slightly larger than the diameter D, of the drum 14. Located circumferentially along the inner wall 20 is a plurality of indentations, for example, holes 26, the function of which will be explained hereinbelow. The diameter of each of the holes 26 is less than the size of the openings 16 of the drum [4.

As shown in FIG. 1, the shaft 12 is positioned in the housing 18 such that the drum 14 is located within the cylindrically shaped inner wall 20 and the openings 16 of the drum 14 are in radial alignment with the plurality of holes 26. (Note that surface 30, associated with the opening 22 of the housing member 18, and the surface of the inner wall 20 act as shaft alignment bearings for the shaft 12.)

Bearings, such as the ball bearings 32, are located within the openings 16 of the drum 14 which forms a race for the ball bearings 32. A collar-like leaf spring 34 (FIG. 4) is located within the drum l4 and exerts a radially outward force against the ball bearings 32 causing them to seat into certain ones of the holes 26 as the shaft is turned. A pin 54 on the inner wall of the drum 14 projects into the opening 56 of the spring 34 to prevent the spring 34 from rotating relative to the drum 14.

It is to be appreciated that the leaf spring 34 and the ball bearings 32 are positioned on the drum 14 before the shaft 12 is placed in the housing 18. To prevent longitudinal travel of the shaft 12 with respect to the housing 18, the shaft 12 includes two

circumferential channels

38 and 40 in which

clip springs

42 and 44, respectively, are inserted. A washer 46 is sandwiched between the clip spring 40 and the base 48 of the housing 18 to limit the longitudinal travel of the shaft 12. A knob (nOt shown) can be mounted on a flat section 50 of the shaft to facilitate turning.

While there has been shown and described what is considered a preferred embodiment of the present invention, various modifications and changes may be made therein without departing from the invention as defined in the appended claims.

What is claimed is:

1. An indexing mechanism comprising:

a shaft having a first diameter and including a drum section coaxial with the longitudinal axis of said shaft, said drum section having an open end and an opening in the wall thereof, the diameter of said drum section being larger than said first diameter;

a housing member having a hollow cylindrically shaped interior with first and second openings in the respective ends thereof, the diameter of said first opening being slightly larger than the first diameter of said shaft, and the diameter of said second opening being slightly larger than the diameter of said drum section of said shaft, said hollow cylindrically shaped interior including a plurality of indentations located circumferentially around the wall thereof, the size of each of said plurality of indentations being slightly less than the size of the openings in the walls of said drum section,

said shaft being positioned in said housing member such that the drum section rotates within the hollow cylindrically shaped interior of said housing member;

a bearing member positioned in the opening in the wall of the drum section of said shaft; and

biasing means positioned within the drum section and exert ing a force on said bearing member in a direction towards said housing member.

2. An indexing mechanism comprising:

a shaft having a first diameter and including a drum section coaxial with the longitudinal axis of said shaft, said drum section having an open end and a pair of openings in the wall thereof, the diameter of said drum section being larger than said first diameter;

a housing member having a hollow cylindrically shaped interior with first and second openings in the respective ends thereof, the diameter of said first opening being slightly larger than the first diameter of said shaft and the diameter of said second opening being slightly larger than the diameter of said drum section of said shaft, said hollow cylindrically shaped interior including a plurality of indentations located circumferentially around the wall thereof, the size of each of said plurality of indentations being slightly less than the size of the openings in the wall of said drum section,

bearing members each positioned in one of the openings in the wall of the drum section of said shaft; and

biasing means positioned within the drum section and exerting a force on said bearing members in a direction towards said housing member.

3. An indexing mechanism according to claim 2 including means for limiting the longitudinal travel of said shaft with respect to said housing member.

4. An indexing mechanism according to claim 3 wherein:

said shaft has a circumferential channel adjacent to each end of said housing member; and

said means for limiting includes:

a clip spring positioned in each of said circumferential channels and having a surface larger than the first diameter of said shaft, and

a washer having a circular void, the diameter of which is slightly larger than said first diameter of said shaft, said washer having an overall diameter greater than the diameter of the second diameter of said housing member and being sandwiched between said housing member and one of said clip springs.

5. An indexing mechanism according to claim 2 wherein said biasing means includes a collar-like leaf spring, the expanded diameter of which is larger than the diameter of the wall of the drum section of said shaft thus causing a radially outward force on said bearing members when compressed in the drum section of said shaft.

6. An indexing mechanism according to claim 2 wherein:

said bearing members are ball bearings;

the diameter of the pair of openings in the walls of said drum section is slightly larger than the diameter of said bearings; and

the indentations of said housing member are circular openings having a diameter less than the diameter of said ball bearings.

7. An indexing mechanism according to claim 6 wherein the diameter of said ball bearings is larger than the thickness of the wall of said drum.

8. An indexing mechanism according to claim 7 wherein the walls of said drum have the openings located diametrically op posite each other.

l i t 22 3 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION I Patent No. 3,677,096 Datedr July 18, 1972 Inventor(s) Raymond G. Har tmen It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading (Item [72] Inventor the inventor should be Raymond G. Hartman-. I

At column 2, line 35, "nOt" should be --not-'-.

Signed and sealed this 26th day of December 1972..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer

Claims

1. An indexing mechanism comprising: a shaft having a first diameter and including a drum section coaxial with the longitudinal axis of said shaft, said drum section having an open end and an opening in the wall thereof, the diameter of said drum section being larger than said first diameter; a housing member having a hollow cylindrically shaped interior with first and second openings in the respective ends thereof, the diameter of said first opening being slightly larger than the first diameter of said shaft, and the diameter of said second opening being slightly larger than the diameter of said drum section of said shaft, said hollow cylindrically shaped interioR including a plurality of indentations located circumferentially around the wall thereof, the size of each of said plurality of indentations being slightly less than the size of the openings in the walls of said drum section, said shaft being positioned in said housing member such that the drum section rotates within the hollow cylindrically shaped interior of said housing member; a bearing member positioned in the opening in the wall of the drum section of said shaft; and biasing means positioned within the drum section and exerting a force on said bearing member in a direction towards said housing member.

2. An indexing mechanism comprising: a shaft having a first diameter and including a drum section coaxial with the longitudinal axis of said shaft, said drum section having an open end and a pair of openings in the wall thereof, the diameter of said drum section being larger than said first diameter; a housing member having a hollow cylindrically shaped interior with first and second openings in the respective ends thereof, the diameter of said first opening being slightly larger than the first diameter of said shaft and the diameter of said second opening being slightly larger than the diameter of said drum section of said shaft, said hollow cylindrically shaped interior including a plurality of indentations located circumferentially around the wall thereof, the size of each of said plurality of indentations being slightly less than the size of the openings in the wall of said drum section, said shaft being positioned in said housing member such that the drum section rotates within the hollow cylindrically shaped interior of said housing member; bearing members each positioned in one of the openings in the wall of the drum section of said shaft; and biasing means positioned within the drum section and exerting a force on said bearing members in a direction towards said housing member.

4. An indexing mechanism according to claim 3 wherein: said shaft has a circumferential channel adjacent to each end of said housing member; and said means for limiting includes: a clip spring positioned in each of said circumferential channels and having a surface larger than the first diameter of said shaft, and a washer having a circular void, the diameter of which is slightly larger than said first diameter of said shaft, said washer having an overall diameter greater than the diameter of the second diameter of said housing member and being sandwiched between said housing member and one of said clip springs.

6. An indexing mechanism according to claim 2 wherein: said bearing members are ball bearings; the diameter of the pair of openings in the walls of said drum section is slightly larger than the diameter of said bearings; and the indentations of said housing member are circular openings having a diameter less than the diameter of said ball bearings.

8. An indexing mechanism according to claim 7 wherein the walls of said drum have the openings located diametrically opposite each other.