US 3580619 A
Description (OCR text may contain errors)
United States Patent  Inventor Frederick Jean Maltais Camp Hill, Pa.
] Appl. No. 17,095
 Filed Mar. 6, 1970  Patented May 25, 1971  Assignee AMP Incorporated Harrisburg, Pa.
 SPRING CLIP Primary Examiner-David J. Williamowsky Assistant ExaminerAndrew V. Kundrat AttorneysCurtis, Morris and Safford, William J. Keating,
Ronald D. Grefe, William Hintze, Adrian J. La Rue, Frederick W. Raring, Jay L. Seitchik and John P. Vanderburg ABSTRACT: A clip has been provided for securing a knob to a D-shaped shaft, by inserting it in an aperture in the knob. The clip is a longitudinally split spring which seizes in the knob and grasps the shaft by means of springlike longitudinally tapered panels cooperating with centering protrusions in said spring thereby frictionally engaging and centering the shaft in the knob. A plurality of projecting, pointed barbs may be provided to depend from the spring and to engage in a locking or seizing relationship the clip spring into the inner wall of the receiving aperture. The centering protrusions also provide a positive engagement as well as proper centering of the D-shaft in the knob aperture, thereby holding the knob on the D-shaft substantially without wobbling and still allowing the D-shaft to be withdrawn and reinserted numerous times without substantial loss of performance.
PATENTEU m2 5 I9?! SHEET 1 [IF 2 PATENTEU MAYZS I971 SHEET 2 BF 2 SPRING CLIP This invention relates the fastening or spring clip means for connecting knobs to shafts; more particularly, this invention relates to spring retention clips used as a connecting means to secure knobs to instrument shafts, such as radios, etc., substantially without any noticeable wobble of the knobs.
In placing knobs on instrument shafts such as are commonly employed with devices of which television, radio and similar receiving instruments are representative, it has been highly desirable to assemble the knob and the retention clip which secures the knob to the instrument shaft in an automatic fashion and at high production rates. However, the proper assembly of the retention clip with the knob is a highly precise operation which requires a careful and well timed mating of the retention clip with the knob. Moreover, rapid assembly techniques have been sought which would replace the manual assembly techniques prevalent in the industry and thus reduce the considerable labor component associated with a seemingly small part in relation to the total cost of the instrument.
PRIOR ART A retention clip which is representative of the manually used type generally heretofore employed is shown in U. S. Pat. No. 2,968,504. This retention clip has been designed for manual assembly in that the symmetry of the clip alleviates the problems of selecting the proper position of the clip in respect to either the front or trailing end of the clip. As it can readily be appreciated, the device which has been illustrated in this patent does not lend itself to a mass assembly technique in that in each instance an individual clip has to be removed manually from a container and placed manually into a knob. Because either of the ends of this spring must be identical as a sacrifice for improved production, the securement obtained with these clips introduces variables resulting in improperly secured knobs, i.e. the knobs wobble. Although the assembly of the prior art clips is facilitated because of the alleged symmetrical performance, the problems introduced by designing a symmetrical knob are numerous especially in terms of a longitudinal securement of a D-shaft and annoying wobble as well as insufficient seizing of the clip in the knob. Thus the clip fails to secure rigidly and without rotational movement the shaft.
Further, it is known such as in a copending application, Ser. No. 855,228, filed Sept. 4, 1969, that various retention springs may be provided which lend themselves easily for automated removal from a continuous strip and mating the same with a knob. However, in the last disclosed invention, it has been found that a new concept further simplifies the desired securement of a knob to a D-shaft and produces an even more reliable and even more desirable means for mating of a knob to a shaft.
Thus, it has now been found that a novel spring clip device contributes to overcoming some of the prior art problems. This clip has means which prevent its removal from the knob and lends itself readily to fast automatic production, and semiassembly, i.e. insertion in the knob. The novel spring at the same time provides for secure and positive engagement of the knob to the shaft without transverse movement characterized commonly as wobble. Furthermore, the tolerance requirements associated with high production rates which have heretofore been expensive to achieve, are solved in an elegant manner by providing a properly designed retention clip spring components which because of their spring action in combination with the centering action provide good securement of the knob to the D-shaft. Moreover, the novel spring provides for a knob which may be repeatedly removed without destruction of the positive and secure engagement of the knob to the D-shaft. Additionally, it has been found that the novel means provide a positive engagement between the knob and the shaft by reason of the centering action achieved by means of the centering projections provided in the retention clip or spring. Other facets and achievements of the present invention will become readily apparent to those skilled in. the art upon following the present detailed description when the same is taken in conjunction with the drawings herein in which there is shown and described an illustrative embodiment of the present invention; it is to be understood, however, that the illustrative embodiment is not intended to be exhaustive or limiting of the invention but is given merely for the purpose of showing to those skilled in the art on how to practice the invention so that the principles thereof can be understood and the manner in which this invention may be applied and if desired be modified to various forms as these may occur to those skilled in the art.
Referring now to the drawings:
FIG. 1 is a perspective and exploded view of an end of a shaft S, the novel retention spring L and a knob K according to the invention herein;
FIG. 2 is a front end view ofthe clip;
FIG. 3 is a longitudinal cross section view of a knob with an inserted retention clip or spring clip in which the clip is in a position which it assumes when it is in a free or nonengaged position with a shaft;
FIG. 4 is a view similar to FIG. 3 with the knob being engaged with the shaft by means of the novel spring clip, the same assuming an engaged position in respect to the shaft;
FIG. 5 is a view taken along the lines 5-5 of FIG. 4 showing the raised centering protrusions in an engaged position with the shaft;
FIG. 6 is a longitudinal view along lines 6-6 of FIG. 4 showing the retention barbs as these are embedded in the knob;
FIG. 7 is a perspective view of two of the novel clips as these appear on a continuous stamping strip from which the novel clips are removed by automated machinery.
Referring now to FIG. I, a knob K such as commonly found on TV or radio receivers and made out of plastic has been found to be suitable for receiving the novel retention spring L when the same is inserted in the knob in the aperture 11 and a shaft S introduced into this aperture and secured to the knob by the novel spring retention clip L. The knob shank 10 has the opening or aperture in the form of a letter D which allows for the positive rotational engagement of shaft because of the particular form defined by the flat portion 12 in the knob and the cylindrical portion 13. Beveled edges 14 are provided on the cylindrical 13 as well as the flat portion 12 of the knob K to allow for easy reception of the novel retention clip. The knob as shown in FIG. 3 has a dead end surface 15 which defines the proper relationship of the knob K in respect to the shaft S and thus to the instrument body.
The shaft S which is generally protruding from the instrument panel is engaged with a knob K having the spring L therein after the instrument has been substantially assembled. This shaft may have a shaft shoulder (not shown) which also may be used for terminating the engagement of a knob with the shaft in the event the dead end surface 15 of the shaft is located further inwardly and the retention clip L is abutting a retention shoulder (not shown). The shaft S may also have its edges beveled such as illustrated in FIG. 1 for proper introduction of the shaft into the knob aperture.
The novel shaft spring L has a flat bottom portion 19 and a cylindrical portion 20. In referring to FIG. 2, the spring in a vertical, longitudinal plane consists substantially of two sections which are mirror images of each other. The flat, bottom section 19 of the spring L is a right-angle rectangle with the two lines where the cylindrical section 20 meet with the flat section 19, being parallel to each other. The cylindrical portion of the spring 20 is tapered from the front or leading edge 25 to the trailing edge 25a. A flattened and tapered spring section 21, is substantially parallel and, again, defines approximately a right-angle rectangle. An appropriate taper for the spring is introduced by the proper deformation of the spring L as it is stamped from a continuous strip illustrated also in FIG. 7. Each of the cylindrical sections 20 has a seizing barb 26 which consists of a flat section 26a and a barb spring section 22 having a barb point 27. The opening, receiving end of the spring, i.e., the leading edge area 25 has the upper, spring area 21 shaped to remove the leading corner edges by die cutting the same and thus producing a bevel 32. The raised centering protrusions 30 are substantially in the form of an indention, i.e. a rectangular, elongated pyramid and projecting for somewhat less than the full width of the section 19. As it is apparent from FIG. 5, when the D-shaft is introduced into the knob, the centering protrusions 30 have the function of providing a positive, restricted engagement area with the D- shaft and thus avoiding the random irregularities which may normally be associated with a flat section of a die-formed thin strip. These irregularities contribute to a knob wobble. Consequently, the action which the centering protrusions exert on the spring is concentrated along the apex line and thus assures the concentricity of the shaft S in the knob K as well as the rigid securement. FIG. 5 illustrates the front view of the spring as the same is being urged in the flattened section peripherally and tangentially against the knob K thereby urging the spring L outwardly and, by the centering projections 30, upwardly against the cylindrical portion B of the knob. This combined action as well as the taper of the spring produces the secure, positive engagement of the knob K to the shaft S.
Referring toFIG. 3, the spring in its nonengaged position is seen to taper towards the dead end surface of the knob K and when the spring L is spring loaded by the D-shaft it also has a tendency to provide a secure positive engagement with the shaft S in the space near the dead end surface 15 by aid of the upward urging attributable to the projections 30.
The engaged spring as illustrated in FIG. 4 with a knob and the shaft being in place shows the action of the upward projection 30, i.e. in a manner of a leveler in its intended configuration.
In FIG. 6, the barb points 27 are engaged in the knob K when the shaft S is inserted and show the positive, longitudinal latching securement provided by the barb means, especially suitable for repeated insertion and withdrawal of shaft S into the knob K.
Finally, the continuous strip from which the spring L is formed in a stepwise fashion as it is well known in the art is shown in FIG. 7 and designated as 37. This strip has strip index holes 39 which are used for positive placement of these springs and mating the same with an assembly device in a manner as further explained herein.
Thus, when the strip 37, as properly indexed by means of the strip holes 39 is fed in an automatic machine (not shown herein) the upwardly projecting leading edge 25 is capable of receiving a loading shaft having a shoulder (not shown) which then engages the spring L and removes the same from the continuous strip 37 projecting upwardly the trailing edge 25a, i.e. the more tapered portion thereof.
The spring L is then brought into a position which allows an automatic receiving of the knobs aperture Ill by the trailing edge 25a of tapered portion of the spring or allows for a manual placement of the knob K on the loading shaft holding the spring clip L. Thereafter, at a further station the knob is forcefully driven onto the shaft which carries the spring L and thus the knob K is positively engaged with the clip L such as shown in FIG. 6. Since the shaft which is used for securing the spring L in a proper position for engagement with knob K must be of reasonably proper dimensions, it can be well appreciated that the tolerances, while these are still critical, are such that the springiness provides for sufficient engagement and mating of the spring L with the knob and thereafter with the shaft S to assure a substantially trouble-free performance.
l. A spring clip for securing a knob to a shaft, said knob having a D-shaped receiving aperture matingly capable of receiving a shaft corresponding to said aperture, said clip comprising a longitudinally split, resilient and tubular member having a first and two each of a second and third longitudinal sections, said first longitudinal section being a substantially planar right angle rectangle, said second longitudinal section intersecting with said right-angle rectangle with each second section extending from one side of said rectan le and together bemg a tapered, cylindrical section from a lea mg edge at one end of said rectangle to a trailing edge at the other end thereof, said third longitudinal section intersecting with said tapered, cylindrical section and each third section being a substantially flat right-angle rectangle extending from one side of said cylindrical sectionv 2. A spring clip for securing-a knob to a shaft as defined in claim 1 and wherein each of the second and third longitudinal sections being approximately a mirror image counterpart with said second sections intersecting opposite, longitudinal edges of said first longitudinal section.
3. A spring clip for securing a knob to a shaft as defined in claim 1 and wherein the second, tapered and cylindrical section has a resiliently depending barb point protruding outwardly for engagement within said receiving aperture.
4. A spring clip for securing a knob to a shaft as defined in claim 1 wherein said third longitudinal section arcuately, transversely engages said shaft.
5. The clip as defined in claim I and wherein the first, longitudinal section has a plurality of protrusions transversely to the longitudinal axis of said section for securement and centering of said knob on said shaft.
6. The clip as defined in claim 5 and wherein the protrusions define a longitudinally rectangular pyramid having an apex line for frictional securement of said shaft to said knob.