US2972493A - Means for attaching a knob or the like to a shaft - Google Patents

Description

Feb. 21, 1961 R. s. WATERS MEANS FOR ATTACHING A KNOB OR THE LIKE TO A SHAFT Filed Feb. 15, 1959 F'IGZ).

INVENTOR ROBERT S. WATERS ATTORNEY United States Patent MEANS FOR ATTACHING A KNOB OR THE LIKE TO A SHAFT Filed Feb. 13, 1959, Ser. No. 793,050

2 Claims. (Cl. 287-53) This invention relates to attaching means and more particularly to means for attaching a knob on the end of a shaft and establishing a driving connection therebetween.

This invention provides a positive, low cost device for holding a removable knob tightly on an apparatus control shaft for the life of the apparatus. According to the present invention, an attaching or holding device for the purpose stated is provided which comprises: a body portion disposed within a longitudinal slot in the end of the shaft and in resilient engagement with the mutually facing surfaces of the slot, a key portion disposed in a longitudinal groove in the tubular wall of a knob cavity and in frictional engagement therewith, and a resilient connecting portion which is bent about the end of the shaft and connects the body and key portions. With the present invention a knob is attached to a shaft which is to be rotated by a turning movement of the knob, the knob being secured against accidental removal even though it can be easily attached to the shaft.

The device makes possible the use of a knob having a keyhole shaped cavity on slotted shafts not having a driving lug as well as on shafts provided with a driving lug. For example, through general industry practice, certain electrical controls, such as thermostats, are generally supplied with shafts having a driving lug thereon for use with keyhole knobs. Other controls, such as onoif switches, are generally provided with slotted shafts intended to have cylindrical cavity knobs press-fitted on the end thereof. Thus, a product having two or more types of control shafts, such as a fan having an adjustable thermostat and an on-off switch, previously required two or more types of knobs, even though all of the knobs had the same exterior appearance. This invention, in providing for the attachment of a keyhole type knob on a slotted shaft, permits knobs of one type to be employed on several controls in one product unit. The particular fastening means of this invention additionally provides a more secure attachment of a slotted shaft to a knob. In other words, this invention is an improvement over the conventional slotted shaft and friction knob connection.

The various objects, features and advantages of the invention will appear more fully from the detail description which follows, taken in connection with the accompanying drawing forming a part of this application, in which:

Fig. 1 is an exploded view of a knob, a slotted shaft, and a device constructed in accordance with the invention for adapting the shaft to fit the knob;

Fig. 2 is an axial sectional view of the parts of Fig. l in assembled relationship; and

Fig. 3 is a vertical sectional view taken transverse to the shaft of Fig. 2 along line IIIIII.

Referring to the drawing in detail, a knob is provided with an axially elongated opening or cavity 12 of keyhole shape defined by an interior cylindrical wall 2,972,493 Patented Feb. 21, 1.961

in which is formed an axial groove or recessed keyway 14. Preferably, the knob 10 has a knurled annular periphery and the cavity 12 is closed atone end by a front wall 16 which serves to limit the extent to which a shaft 18 may be inserted therein.

The shaft 18 fits the cylindrical wall of the cavity 12, and, as shown, has an axially extending, diametric slot 20 at one end and a pair of oppositely facing fiat surfaces 22 in an otherwise cylindrical exterior surface. When, in accordance with the prior practice, a knob having a cavity made to fit the shape of this kind of shaft is attached thereto, the surfaces 22 serve as driving surfaces. However, the shaft 18 need not have flat surfaces 22 to establish a driving connection between the knob 10 and shaft 18 when the present invention is used; the shape of the shaft shown is that of a conventional on-ofl switch and merely typifies the slotted control shafts to which this invention is applicable.

In accordance with the invention, a device 24 is provided for attaching the slotted or bifurcated end of the shaft 18 within the knob cavity 12 and for establishing a driving connection between the shaft and the knob. The device 24 comprises a generally U-shaped member of spring sheet metal, which member includes a body portion or first leg 26 at one end thereof, a key portion or second leg 28 at the other end thereof, and a connecting or intermediate portion 30 which connects the first and second legs. The first leg 26 is axially disposed within the slot 20 and is of less width than the slot, so that the side edges of the leg 26 do not lie beyond the surface of the shaft 18. Furthermore, the leg 26 is arched, undulated, or otherwise formed to frictionally and resiliently engage the mutually facing surfaces of the slot 20, whereby the leg 26 is received tightly in the slot 20 and resists deflection of the bifurcated end of the shaft tending to close the slot 20.

The intermediate portion 30 is bent reversely about the end of the shaft 18 and connects the first leg 26 to the second leg 28, the latter extending along the shaft in the knob keyway 14. The arrangement is such that legs 26 and 28 are inclined to each other at a greater angle before assembly than after assembly; in other words, the free ends of the legs are moved toward each other against the bias of the intermediate portion 30 when the knob 10 is attached to the shaft 18 and the second leg 28 frictionally engages the walls of the keyway 14. It is desirable that the second leg 28 be substantially as wide as the keyway 14 in order to prevent undesirable relative movement between the knob 10 and the shaft 18.

As mentioned previously, the keyhole shaped cavity 12 is frequently provided on knobs which are attached to shafts of various controls including adjustable thermostats. The slotted shaft 18 is of a shape commonly used with another variety of controls including on-off switches.

The device 24 effectively and inexpensively adapts the slotted shaft 18 for use with otherwise incompatible knobs. With the present invention, fewer types of knobs are required where several knobs had been required previously.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. In combination, a shaft provided at one end with an axial slot, a knob provided with an opening defined by a generally cylindrical wall in which is formed an axially extending groove, and a device for attaching the slotted end of saidshaft within said knob opening and for establishing a driving connection between said knob and said shaft, said device comprising a generally U-shaped strip of spring sheet metal having a first end 3 portion disposed in said slot, an intermediate portion bent reversely about the end of said shaft, and a second end portion extending along the exterior surface of said shaft, said second end portion being received in said groove and in frictional engagement with a wall portion of said groove, said first end portion having an arched section frictionally and resiliently engaging the mutually facing surfaces of said slot.

2. In combination, a shaft provided at one end with bifurcations defining an axially extending, diametric slot between said bifurcations, a knob provided with a cavity in which said one end of said shaft is received, said knob cavity being defined by a generally cylindrical wall in which is formed an axially extending groove, and a device comprising: a generally U-shaped strip of, spring sheet metal including an undulated end portion disposed in said slot in frictional engagement with said bifurcations to 4 retain said undulated end portion in said slot and to resist inward deflection of said bifurcations, and another end portion extending exteriorly of the surface of said shaft and disposed in said groove in frictional engagement with at least one wall thereof to establish a driving and retaining connection with said knob.

References Cited in the file of this patent UNITED STATES PATENTS 1,576,062 Passmore Mar. 9, 1926 1,600,975 Calkins Sept. 2-8, 1926 1,920,021 Shroeder July 25, 1933 2,153,950 Whinery Apr. 11, 1939 2,564,550 Tichenor Aug. 14, 1951 FOREIGN PATENTS 65,224 Netherlands Feb. 15,

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