Adjusting knob assembly with discrete positioning

Abstract: An adjusting knob assembly (1) includes a knob member (3) having a knob (7) and an axially extending shaft (15). A support bracket (5) has an aperture (23) defined in part by a gapped ring section (25) formed by a pair confronting arcuate fingers (27). The shaft (15) and the aperture have complimentary, longitudinally extending, circumferentially distributed flat surfaces (17; 33, 35), which provide discrete angular positions for the shaft (15) when the complimentary flat surfaces (17; 33, 35) are in register. Preferably, the gap (29) between the confronting fingers (27) is sized, and the arcuate fingers (27) have a compliance sufficient that the shaft (15) may be passed laterally through the gap (29) and snapped into the aperture (23). Any one of a plurality of interchangeable cam members (43) can be press fit on to the end of the shaft (15).

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to rotatable adjusting knobs, and particularly to an adjusting knob assembly including a positioner which locates the rotatable knob at discrete angular positions. Background Information There are many applications for rotatable adjusting knobs where it is desirable to position a knob at a number of discrete angular positions. One such adjustable knob utilizes a ball housed in a radial bore in a collar supporting a knob shaft. The ball is spring biased to bare against flats on the shaft to establish the discrete angular positions of the knob. Such an arrangement is effective, but requires a number of parts which must be fabricated and assembled. It also requires considerable space which is not always available. There is a need for an improved adjusting knob assembly which is simple yet effective in retaining the knob at discrete angular positions. There is an additional need for such an improved adjusting knob assembly which can be economically fabricated and assembled. There is also a need for such an improved adjusting knob assembly which requires minimum space. Further attention is drawn to DE-A-3335575 which discloses an assembly in accordance with the preamble of claim 1. In accordance with the present invention an adjusting knob assembly as set forth in claim 1 is provided. Preferred embodiments of the invention are disclosed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: Figure 1 is an isometric view of an adjusting knob assembly in accordance with the invention. Figure 2 is an exploded isometric view of the adjusting knob assembly of Figure 1 rotated 90° from the orientation of Figure 1. Figure 3 is a fragmentary, sectional view in enlarged scale illustrating features of the preferred embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, the adjusting knob assembly 1 of the invention includes a knob member 3 and a support bracket 5 which also serves as a positioner. The knob member 3 comprises a knob 7 which includes a knob head 9 projecting axially beyond a knob flange 11. The knob head 9 is shown in the exemplary embodiment as a cylindrical member having a slot 13 for insertion of a screw driver. The particular configuration of the knob is not an essential feature of the invention. For instance, the knob could be fluted or ribbed for grasping with the fingers, and could be polygonal in cross-section, or any other configuration. The particular slotted head 9 shown is useful for instance, in making adjustments in trip settings of a thermal-magnetic circuit breaker, but it will be understood that this is an exemplary use only. The knob member 3 further includes a shaft 15 extending axially from the knob 7. The shaft 15 has a plurality of axially extending, circumferentially spaced flat surfaces 17. The exemplary shaft has 8 such flat surfaces 17 equiangularly spaced. As best seen in Figure 3, cylindrical sections 19 are preferably provided on the shaft 15 between the flat surfaces 17. Other numbers of flat surfaces could be provided dependent upon the number of discrete angular positions desired. The support bracket 5 includes a planar body 21 which defines an aperture 23. The aperture 23 is formed in part by a compliant, gapped ring section 25 of the planar body 21. This gapped, ring section 25 is formed by a pair of confronting arcuate fingers 27 spaced apart to form the gap 29. The arcuate fingers 27 have a compliance, and the gap 29 has a width, such that the shaft 15 of the knob member 3 can be pushed laterally through the gap 29 and snapped into the aperture 23. Beveled outer corners 31 on each of the arcuate fingers 27 serve as guides for inserting the shaft and wedge the arcuate fingers apart to enable the shaft to pass through the gap 29. The aperture 23 has axially extending flat surfaces two of which 33 are on the ends of the arcuate fingers 27 adjacent gap 29. These flat surfaces are complimentary to the flat surfaces 17 on the shaft. A third complimentary flat surface 35 in the aperture 23 is centered opposite the gap 29. The remaining surface 37 of the aperture is cylindrical and complimentary to the cylindrical surfaces 19 on the knob shaft 15. The support bracket 5 has an arrangement for mounting the knob assembly in an appropriate location within a device in which the knob is to be used. In the exemplary arrangement, the support bracket 5 has a mounting flange 39 with mounting holes 41 for receipt of suitable fasteners (not shown). The knob member 3 also includes an engagement member 43 for engaging the device to be adjusted with the knob. In the exemplary assembly 1 this engagement member is in the form of cam member. Preferably, the cam member 43 is removably secured to the free end 45 of the knob shaft 15 so that a plurality of interchangeable cam members 43 can be used with a standard knob member 3. In the exemplary adjusting knob assembly, the cam member 43 is removably secured to the shaft 15 by a mount 46 which includes an axially projecting pin 47 on the shaft 15 and an aperture 49 in the cam member 43. The pin 47 is keyed by a flat surface 51 which engages a similar flat 53 in the aperture 49 to assure that the cam member rotates with the knob shaft 15. The exemplary cam member 43 has an axial facing camming surface 55. Alternatively, the camming surface could face radially. In use, the support bracket 5 it mounted in a desired location using fasteners (not shown) inserted through the mounting holes 41 in the flange 39. The appropriate interchangeable cam member 43 is press fit on to the pin 47 on the knob shaft 15. The knob shaft 15 is inserted in the gap 29 and pressed laterally to spread arcuate fingers 27 apart through the wedging action produce by the beveled corners 31 until the shaft snaps into place in the aperture 23. The knob member 3 can then be rotated to any one of eight angular positions in which the flat surfaces 17 on the shaft 15 register with the complimentary flat surfaces 33 and 35 in the aperture 23. The support bracket 5 is preferably molded from a material having a compliance sufficient for the arcuate fingers to spread apart as the knob is rotated and to initially allow the lateral insertion of the shaft 15 into the aperture 23. A suitable material is a resin such as polycarbonate. The knob member 3 may be molded of a similar material, although this is not required. The adjustable knob assembly of the invention provides a simple, inexpensive, easily produced adjustment device which requires very little space. While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention defined by the claims appended.

Claims: An adjusting knob assembly (1) comprising: a knob member (3) having a knob (7) and a shaft (15) extending axially from said knob (7) and terminating in a free end; and a support bracket (5) having an aperture (23) defined at least in part by a compliant, gapped ring section (25), one of the shaft (15) and aperture (23) having a plurality of longitudinally extending, circumferentially distributed flat surfaces (17; 33, 35), and the other having at least one complimentary flat surface (33, 35:17), said shaft (15) and aperture (23) being dimensioned such that said shaft (15) is pliantly retained at any of a plurality of rotational positions within said aperture (23) at which said flat surfaces (17; 33,35) on said shaft (15) and aperture (23) are in register, characterized in that said gapped ring section (25) is formed by a pair of confronting compliant arcuate fingers (27) spaced apart to form a gap (29), said gap (29) having a width and said arcuate fingers (27) having a compliance sufficient for said shaft (15) to be passed laterally through said gap (29) into said aperture (23). The adjusting knob assembly (1) of Claim 1 wherein said shaft (15) has said plurality of longitudinally extending circumferentially distributed flat surfaces (17) with cylindrical surfaces (19) between said flat surfaces. The adjusting knob (1) assembly of Claim 1 or 2 wherein said arcuate fingers (27) have beveled outer corners (31) for guiding said shaft laterally into said gap (29). The adjusting knob assembly (1) of Claim 3 where said arcuate fingers (27) each have one of the complimentary flat surfaces (33) adjacent said gap (29). The adjusting knob assembly (1) of Claim 4 where in said plurality of longitudinally extending flat surfaces (17) are equiangularly circumferentially distributed on said shaft (15). The adjusting knob assembly (1) of Claim 1 wherein said shaft (15) has eight equiangularly spaced flat surfaces (17) circumferentially distributed, and where in said aperture (23) has a third complimentary flat surface (35) centered opposite said gap (29). The adjusting knob assembly (1) of Claim 6 wherein said shaft (15) has cylindrical surfaces (19) between said longitudinally extending flat surfaces (17), and wherein said aperture (23) has complimentary cylindrical surfaces (37) on said aperture (23) between the complimentary flat surfaces (33, 35) on said aperture (23). The adjusting knob assembly (1) of Claim 7 including a cam member (43) on said free end (45) of said shaft (15). The adjusting knob assembly (1) of Claim 8 wherein said cam member (43) is a separate piece from said shaft (15), and including mounting means (46) securing said cam member (43) to said shaft, said cam member (43) being one of a plurality of interchangeable cam members (43).

Inventors: KOLBERG KENNETH DANIEL, MORRIS KIMBERLEY, PARKS DAVID ALLEN, SCHACHNER JAMES ROBERT, KOLBERG, KENNETH DANIEL, MORRIS, KIMBERLEY, PARKS, DAVID ALLEN, SCHACHNER, JAMES ROBERT
Applicants: EATON CORP, EATON CORPORATION
Application year: 1997
Main classification: G05G5
IPC codes: H01H71, H01H19, G05G5