US2906112A - Keyway shutters for cylinder locks - Google Patents

Description

Sept. 29, 1959 c. A. VAHLSTROM KEYWAY SHUTTERS FOR CYLINDER LOCKS Filed Dec. 18. 1956 INVEN TOR. ('HRL fl. Vii/ 187F007 KEYWAY SHUTTERS FOR CYLINDER LOCKS Carl A. Vahlstrom, New Britain, Conn., assignor to The American Hardware Corporation, New Britain, Conn, a corporation of Connecticut Application December 18, 1956, Serial No. 629,049

Claims. (Cl. 70-455) This invention relates generally to key operated cylinder locks, and more particularly to shutter means for sealing the keyway of such locks against the entry of dirt and moisture.

Locks of the type for which this invention is particularly intended comprise a lock housing having a bore in which a key plug is mounted to rotate. The key plug contains an axially extending keyway which opens to its periphery and is normally prevented from rotating by a plurality of tumbler elements which are movable to an ineffective position upon insertion of a proper key into the keyway to free the key plug for rotation.

Many different types of keyway shutters have heretofore been devised, but all known prior devices have either been attached to the exterior of the housing or the key plug or have required the use of exterior elements of one type or another for retaining the shutter member or members in position. Such exteriorly attached elements increased the cost of the locks and, in some cases, prevented their use on devices where a lock having a keyway shutter was desired. This was particularly true in the case of door locks requiring a cylinder lock in the outer knob thereof where the particular manner in which the cylinder look was installed in the knob did not permit the use of exterior attachments on the housing or the key plug and therefore prevented the use of keyway shutters in such applications.

The primary object of the present invention, therefore, is to provide a cylinder lock having shutter means for the keyway carried internally of the key plug and which require no exterior attaching means of any kind for retaining the shutter elements therein.

A further object of the present invention is to provide keyway shutter means for a cylinder lock which in no way affect the external dimensions of the lock or its appearance and are, therefore, particularly adapted for use in cylinder locks used in the outer knobs of door locks and the like.

Another object of this invention is to provide keyway shutter means which may be adapted to many different types of cylinder locks without requiring extensive modification thereof.

A still further object of the invention is to provide keyway shutter means which are particularly adapted for use in cylinder locks in which the keyway in the key plug opens to the periphery of the plug.

A still further object of the present invention is to provide keyway shutter means for a cylinder lock which are constructed in a novel manner and are inexpensive to produce.

Further objects and advantages of the present invention will be more clearly understood from the following description and the accompanying drawing in which:

Fig. 1 is an end view of a cylinder lock embodying my novel shutter means.

Fig. 2 is' a side view thereof, partially in central vertical section, further illustrating said shutter means.

Fig. 3 is an enlarged end view of the lock taken in vertical section on line 33 of Fig. 2 and illustrating the keyway shutters in closed position.

Fig. 4 is a sectional bottom view taken substantially on line 4--4 of Fig. 3.

Fig. 5 is a view similar to Fig. 3, but showing the shutters in open position and a key in the keyway of the lock.

Fig. 6 is an end view of the key plug partially in vertical section.

Fig. 7 is a fragmentary view of said key plug.

The cylinder lock in which I have chosen to illustrate my invention is of a conventional pin tumbler type and is particularly adapted for use in the outer knobs of door locks, but it will be readily understood from this disclosure that my invention is applicable to many other types of cylinder locks.

The cylinder lock includes a cylindrical housing 5 having a pin tumbler chamber 6 extending radially therefrom. The housing 5 is provided with an axial bore 7 in which a cylindrical key plug 8 is mounted to rotate. In the particular lock shown, the key plug 8 is provided ,at its outer end with a flange 9' providing an annular shoulder 10 on the plug which engages the end of the housing 5 and prevents axial movement of the plug inwardly relatively thereto. The key plug extends through the bore in the housing and is retained against outward axial movement with respect thereto by a suitable C-ring 11, and the inner end of the key plug carries an axially extending blade 12 which is attachable to the mechanism ,controlled by the cylinder lock. The key plug contains an axially extending keyway 13 which opens to the front of the flange 9 and along one side of the plug and said plug is normally prevented from rotating by a plurality of pin tumblers 14 which are slidable in normally aligned radial openings in the chamber 6 and the key plug and are urged into locking position, fas illustrated in Fig. 2, by tumbler springs as shown at 15. The tumblers 14 are shifted into shear position permitting rotation of the key plug upon insertion of the proper key into the keyway 13.

Since it is desirable to prevent the entry of foreign matter into the keyway, I have provided novel keyway shutters for closing that portion of the keyway located in the bore of the housing and containing the tumbler mechanism. In accordance with my invention, a portion of the key plug directly behind the shoulder 10 on the flange is cut away to provide a transverse slot 16 therein which opens around the opposite sides and bottom of the peripheral surface of the key plug. The slot extends across the keyway, as best shown in Figs. 3, 5 and 6, and is cut in such a manner that its upper edge is defined by oppositely inclined surfaces 16a-16a which extend from opposed points on the periphery of the plug toward the edge of the keyway and meet at the center of the key plug at a point above said edge. It will be noted from Figs. 2 and 4 that the slot 16 is disposed entirely within the bore 7 so that the opening around the periphery of the key plug is closed by the wall of the bore.

Prior to the formation of the slot 16, opposed transverse holes are drilled into the key plug on the opposite sides of the keyway at predetermined angles corresponding to the angles of the edge portions. 16a--1 6a of the slot, and said holes preferably open into the keyway. The holes are drilled on axes located substantially at the predetermined center of the slot and are larger than the slot so that after said slot is formed, its opposite walls contain opposed recesses 1717 at opposite sides of the keyway which extend parallel to the adjacent edge portions 16a16a; the recesses in the front wall of the slot extending outwardly to the periphery of the flange 9."

Within the slot 16, there is contained a pair of opposed transversely slidable shutter plates il818, one ateach side of the keyway, having inner edge portions 18a-18a adapted to meet at the center of the keyway and thereby close the keyway. The shutter plates are preferably bevelled along their meeting edges to provide forwardly facing cam surfaces 18b18b and the outer edges of said shutter plates are curved on a radius conforming substantially to the radius of the key plug. Each of said shutter plates contains an angular lydisposed notch 19 which extends inwardly from its outer edge and is aligned with the adjacent recesses 1717 to accommodate a compression spring which is disposed in said recesses and acts between the inner edge of the notch and the wall of the bore in the housing 5. The springs 2020 urge the shutter plates into closed position and also exert a downward force thereon to maintain their lower ends against the wall of said bore, as illustrated in Fig. 3. It will also be noted from Fig. 3 that the upper edges of the shutter plates extend parallel to the notches 19-19 and to the adjacent edge portions 16a16a of the slot 16.

When the proper key, indicated at 21, is inserted into the keyway, the shutter plates 18-48 will be forced apart upon engagement of the end of the key with the cam surfaces 18b18b to allow passage of the key into the portion of the keyway rearwardly of said slot. As the shutter plates move apart, the lower edges slide along the wall of the bore and the resulting movement of the plates is therefore angular. The angle of inclination of the upper edges 16a16a of the slot 16, the upper edges of the plates 1818, the recesses 17-17 and the notches 1919 correspond to the angle of movement of the plates, and it will therefore be understood that the springs 20-20 are axially compressed as the said shutter plates are moved to open position, as illustrated in Fig. 5. If desired, the end of the key can be bevelled to provide cam surfaces on its opposite sides which engage the cam surfaces 18b18b to facilitate spreading of the shutter plates.

When the key is withdrawn from the keyway, the springs 2020 will move the shutter plates angularly into closed position. The lower edges of said plates are always maintained against the wall of the bore by the springs and it will therefore be understood that my novel shutter means is particularly useful in cylinder locks wherein the keyway opens to the periphery of the key plug.

I claim:

1. A cylinder lock comprising a lock housing having a bore, a key plug mounted to rotate in said bore and having an axially extending keyway opening to its front end and along its periphery, said key plug having a transverse slot therein opening around its periphery from the opposite sides of said keyway and extending across the entire keyway, said slot being disposed entirely within said bore, a pair of opposed shutter plates contained within said slot and having meeting edge portions adapted to close said keyway, the lower end portions of said shutter plates being slidable upon the wall of the bore whereby said plates are guided for angular movement in opposite directions between positions closing and opening said keyway, and a pair of springs contained within said slot, one acting between each of said shutter plates and the adjacent wall of the bore and normally biasing said plates into keyway closing position each of said springs being so disposed that the force exerted thereby is applied to its respective shutter plate in a direction substantially parallel to the direction of movement of said shutter plate thereby to press the said lower end portion of the shutter plate against the wall of the bore.

2. A cylinder lock comprising a lock housing having a bore opening to its front end, a key plug mounted to rotate in said bore and having a flange on its front end providing an annular shoulder abutting the marginal edge portion of said bore at the front end of said housing, said key plug having an axially extending keyway opening to its front end and along its periphery and a transverse slot extending rearwardly from said shoulder and across the entire keyway, said slot opening around the periphery of the key plug from the opposite sides of the keyway and being disposed entirely within said bore, a pair of opposed transversely slidable shutter plates contained within said slot and having meeting edge portions adapted to close said keyway, the lower edges of said shutter plates being slidable on the wall of the bore whereby said plates are guided for angular movement between closed and opened positions, said shutter plates having notches extending inwardly from their outer edges at an angle corresponding to their angle of movement, and the opposite walls of said slot having opposed recesses aligned with said notches and extending inwardly from the peripheral surface of the key plug, a compression spring disposed in the recesses at each side of said key plug and in the notch in the adjacent shutter plate and acting between the bottom of its respective notch and the adjacent wall of the bore to normally bias the shutter plate into keyway closing position, said springs maintaining the lower edges of said shutter plates in engagement with said wall.

3. In a key operated cylinder lock, a housing having a circular bore, a key plug mounted to rotate in said bore and having an axial keyway opening to its front end and along its periphery, said key plug having a transverse slot therein disposed in said bore, a pair of opposed shutter plates movable in said slot and having meeting edge portions adapted to close said keyway, the ends of said shutter plates adjacent the periphery of the key plug being slidable on the wall of the bore and guided thereby for angular movement in opposite directions between positions closing and opening said keyway, the edge of said slot being V-shaped with the two surfaces thus formed extending from a point above the center of the keyway to the periphery of the key plug substantially parallel to the direction of movement of the adjacent shutter plate, and spring means in said slot normally yieldably maintaining said shutter plates in keyway closing position.

4. In a key operated cylinder lock, a housing having a circular bore, a key plug mounted to rotate in said bore and having an axial keyway opening to its front end, said key plug having a transverse slot therein disposed in said bore and extending across the entire keyway, a pair of opposed shutter plates slidable in said slot and having meeting edge portions adapted to close said keyway, a compression spring in said slot acting between each of said shutter plates and the wall of said bore and normally yieldably maintaining said shutter plates in keyway closing position, the walls of said slot having opposed recesses extending inwardly from the periphery of the key plug for receiving said springs whereby said springs are prevented from bending during rotation of said key plug.

5. In a key operated cylinder look, a lock housing having a bore, a key plug mounted to rotate in said bore and having an axial keyway opening to its front end, said key plug having a transverse slot therein extending across the entire keyway and disposed in said bore, a pair of opposed shutter plates slidable in said slot and having meeting inner edge portions adapted to close said keyway when in abutting relation, each of said shutter plates having a notch extending inwardly thereinto from its outer edge, and an elongated, coil, compression spring disposed in each of said notches and acting between the bottom thereof and the wall of the bore to normally yieldingly maintain said shutter plates in keyway closing position.

References Cited in the file of this patent UNITED STATES PATENTS 1,560,868 Shinn Nov. 10, 1925 1,965,942 Jacobi July 10, 1934 FOREIGN PATENTS 593,540 Germany Feb. 27, 1934 638,078 France Feb. 14, 1928

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