US3091490A - Detent mechanism for securing a knob to a door latch - Google Patents

Description

May 28, 1963 M. E. WILLIAMS 3,091,490

DETENT MECHANISM FOR SECURING A KNOB TO A DOOR LATCH Filed Aug. 8, 1960 FIG.

MURRAY E. WILLIAMS INVENTOR.

BY (B. fi/l ig United States Patent Ofifice 3,091,490 Patented May 28, 1963 3,091,490 DETENT MECHANISM FOR SECURING A KNOB TO A DOOR LATCH Murray E. Williams, Grand Rapids, Micln, assignor to Dexter Industries, Inc., Grand Rapids, Mich, a corporation of Michigan Filed Aug. 8, 1960, Ser. No. 48,156 2 Claims. (Cl. 292352) This invention relates to the construction of door latches, and particularly to the mechanism for detachably securing a knob to the tubular sleeve conventionally used to transfer torque fro-m the knob to the latch for retracting the bolt. It is desirable that this detachable coupling should be engageable with a simple push-on movement, and should be disengageable without the use of special tools other than that normally used for multiple purposes by a workman. The knob, however, must not be disengageable under conditions that would provide unauthorized access to the interior of the latch mechanism.

It is conventional practice to secure a knob in position on a tubular sleeve through the action of a detent mounted for sliding movement with respect to the sleeve in a direction corresponding to a diameter through the sleeve axis. This detent engages an opening in a cylindrical shank extending from the knob, and can usually be released by the manipulation of a screw driver in a manner such as to force the detent inwardly and out of the shank opening. An example of this type of mechanism is shown in Patent Number 2,694,309. This invention provides an improvement on this type of structure, particularly with regard to the engagement of the knob with the detent on installation, and also with regard to the mounting of the spring for biasing the detent to locking position. The several features of the invention will be analyzed in detail through a discussion of the particular embodiment illustrated in the accompanying drawing. In the drawing:

FIGURE 1 presents a fragmentary section in side elevation showing a knob locked in engagement with a knob sleeve.

FIGURE 2 presents a perspective view showing a knob as it is first inserted over the end of the knob sleeve, and prior to the engagement with the retaining detent.

FIGURE 3 illustrates an intermediate position at which the detent is being retracted as the knob is progressively forced into the fully-engaged position shown in FIG- URE 1.

FIGURE 4 presents a plan view of the detent itself.

The knob sleeve is a tubular structure normally associated with a conventional door latch mechanism (the remainder of which is not shown in the drawing), and usually carries a pair of roll-back cams of the type shown at 11 and 12 for operating the retractor mechanism of the latch. The primary function of the sleeve 10 is to transfer the manually-supplied torque from the knob 13 to the latch mechanism where it can be converted to forces exerted by the cams 11 and 12. Except for the portions relating to the support and construction of the detent for retaining the knob 13 in position, the illustrated sleeve 10 is conventional in its construction.

The sleeve 10 is provided with a pair of diametrically opposite slots, one of these being shown at 14. These slots are parallel to a plane perpendicular to the axis of the sleeve 10, and receive the detent in sliding engagement. If the amount of the desired sliding movement of the detent 15 exceeds or approaches the thickness of the material of the sleeve 10, the material of the sleeve 10 adjacent to one or both of the slots 14 may be depressed radially inward with respect to the axis of the sleeve 10. The interior of the detent 15 is usually cutaway as shown at 16 to provide clearance for operating mechanism which may be confined within the sleeve 10. The portions 17 and the projection 18 slide within the slots 14.

The locking projection 18 extends radially outward a sufficient amount to engage the opening 19 in the cylindrical shank 20 which is fixed with respect to the knob 13. The opening 19 may be a pierced hole or any conveniently-shaped discontinuity capable of receiving a portion of the projection 18. The shoulders 21 and 22 abut the inside surface of the sleeve 10, and serve as a stop limiting the outward movement of the detent 15 under the urging of the spring wire 23. An axial slot 24 is provided in the sleeve 10 intersecting the slot 14, illustrated in the drawing. This axial slot provides clearance for the deflection of the spring wire 23 during the movement of the detent 15. The spring wire 23 is held in position through engagement with the loop 25 of material preferably lanced from the sleeve 10. On assembly, the spring wire 23 is inserted through the hole 26 in the detent 15, and through the loop 25. The loop may then be deformed somewhat to secure the spring in position. It is noteworthy that this construction permits the use of a completely straight piece of steel wire for the spring 23', which requires nothing more than a cut-oif operation in the manufacture of this component. It is notorious that the tolerances in bending of spring steel wire are very difiicult to maintain, and this arrangement eliminates a very troublesome problem.

The knob shank 20 is provided with a preferably V-shaped notch 27 axially opposite the opening 19. The surfaces 28 and 29' of the detent 15 form an outwardlyconverging end to the projection 18, and cooperate with the edges of the shank 20 which form the notch 27 to retract the detent 15 as the knob is axially shoved into engagement with the sleeve 10. As a result of the tapering conformation of the notch 27, the engagement of the sleeve 20 takes place with the surfaces 28 and 29, rather than with the exposed transverse face of the detent 15. FIGURE 3 illustrates the result of this engagement, and the axial movement of the knob into the assembled position will result in retracting the detent 15 inwardly to the point where it will slide underneath the shank 20 until it can snap into engagement with the opening 19. This locked condition is shown in FIGURE 1. Removal of the knob is accomplished by inserting a screw driver at the opening 19 and engaging the end of the projection 18 so that it can be pushed radially inward to the point where the knob can be withdrawn.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

I claim:

1. In a latch mechanism having a knob and a sleeve normally receiving said knob for transferring torque from said knob to said latch mechanism and supporting said knob, said sleeve having an axially-extending slot in the periphery thereof and an outwardly-extending oircumferentially disposed loop opposite the end of said slot, a system for detachably securing said knob to said sleeve comprising: a shank member normally fixed with respect to said knob and engageable axially with said sleeve, said shank member having an opening in the wall thereof and a notch axially aligned with said opening providing cam surfaces diverging to increased width to the end of said shank; detent means slidably mounted in said sleeve for movement transversely to the axis of said sleeve at a position intersecting said slot, said detent means having a hole and stop means limiting the outward movement thereof, and also having a projecting portion of substantially uniform thickness tapening outwardly with respect to said sleeve to reduced width in a plane normal to the axis of said sleeve and receivable in said opening, said projecting tapering portion extending substantially radially from the periphery of said sleeve for engagement with said cam surfaces in the position of said detent determined by said stop means; and biasing means urging said detent toward said position, said biasing means including an initially straight piece of wire disposed adjacent said slot and engaging said detent hole and loop in said sleeve.

2. In a latch mechanism having a knob and a sleeve normally receiving said knob for transferring torque from said knob to said latch mechanism, a system for detachably securing said knob to said sleeve comprising: a shank member normally fixed with respect to said knob and engageable axially with said sleeve, said shank member having a discontinuity in the wall thereof and a notch axially aligned with said discontinuity providing cam surfaces diverging to increased width to the end of said shank; detent means slid-ably mounted in said sleeve for movement transversely to the axis of said sleeve and having a projecting portion of substantially uniform thickness tapering outwardly with respect to said sleeve to reduced width in a plane normal to the axis of said sleeve to define edges engageable with said cam surfaces and receivable in said discontinuity; and biasing means urging said detent toward engagement with said discontinuity.

References Cited in the file of this patent UNITED STATES PATENTS 2,801,123 Kubik et a1 July 30, 1957 2,842,389 Muttart July 8, 1958 2,850,313 Check et al. Sept. 2, 1958

Claims (1)

1. 2. IN A LATCH MECHANISM HAVING A KNOB AND A SLEEVE NORMALLY RECEIVING SAID KNOB FOR TRANSFERRING TORQUE FROM SAID KNOB TO SAID LATCH MECHANISM, A SYSTEM FOR DETACHABLY SECURING SAID KNOB TO SAID SLEEVE COMPRISING: A SHANK MEMBER NORMALLY FIXED WITH RESPECT TO SAID KNOB AND ENGAGEABLE AXIALLY WITH SAID SLEEVE, SAID SHANK MEMBER HAVING A DISCONTINUITY IN THE WALL THEREOF AND A NOTCH AXIALLY ALIGNED WITH SAID DISCONTINUITY PROVIDING CAM SURFACES DIVERGING TO INCREASED WIDTH TO THE END OF SAID SHANK; DETENT MEANS SLIDABLY MOUNTED IN SAID SLEEVE FOR MOVEMENT TRANSVERSELY TO THE AXIS OF SAID SLEEVE AND HAVING A PROJECTING PORTION OF SUBSTANTIALLY UNIFORM THICKNESS TAPERING OUTWARDLY WITH RESPECT TO SAID SLEEVE TO REDUCED WIDTH IN A PLANE NORMAL TO THE AXIS OF SAID SLEEVE TO DEFINE EDGES ENGAGEABLE WITH SAID CAM SURFACES AND RECEIVABLE IN SAID DISCONTINUITY; AND BIASING MEANS URGING SAID DETENT TOWARD ENGAGEMENT WITH SAID DISCONTINUITY.

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