In response to the American with Disabilities Act and other state and local codes, levers have virtually replaced knobs in the marketplace. The benefit of added grip and leverage that levers provide to those with limited mobility has, however, created an opportunity for increased abuse or vandalism. This abuse often renders the lock inoperable and, in some cases, violates the security of the door, leaving computer and laboratory equipment susceptible to theft.

The foregoing illustrates limitations known to exist in present levered door locks. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one Dr more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.

One prior art clutching door lock is described in U.S. Patent No. 4,920,773, Surko et al. Surko discloses a clutching mechanism where a radially extending dog extends through a T-shaped slot in an outer spindle to connect a lever to the outer spindle. Another example of a clutching door lock is described in U.S. Patent No.

2,998,274, Tornoe et al. Tornoe discloses a clutching mechanism having a center spindle that telescopes within the outside spindle and is selectively clutched to the outside spindle. A third example of a clutching door lock is described in U.S. Patent No.

2,998,274, Russell. Russell discloses clutching an outside spindle to a telescoped center spindle by a clutch consisting of a finger and a notch comprising a longitudinal slot and an adjoining

circumferential space. An example of a lock camming mechanism is described in International Patent Application WO 98/02630, published 22 January 1998.

SUMMARY OF THE INVENTION In one aspect of the present invention, this is accomplished by providing a door lock comprising: an inner handle; an outer handle; a chassis containing a latch retractor; an inner spindle having latch scoops thereon, the latch scoops being operably connected to the latch retractor, the inner spindle being keyed to the inner handle; an outer spindle being keyed to the outer handle; a key spindle positioned within the outer spindle, the key spindle having two latch scoops thereon, the latch scoops being operably connected to the latch retractor, and having a cam therein; and a key operated cylinder operably connected to the cam.

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. 1 is an exploded perspective of the door lock with the clutching mechanism of the present invention; FIG. 2 is an exploded perspective of the chassis shown in FIG.

1; FIG. 3 is a side view of the key spindle and cam shown in FIG.

2, illustrating a dogging arm and T-shaped clutch slot; FIG. 3A is a cross-sectional view of the key spindle and cam shown in FIG. 3; FIG. 3B is an end view of the key spindle and cam shown in FIG. 3 illustrating a lost motion bow-tie shaped plug stem;

FIG. 4A is cross-sectional view of a second embodiment of the key spindle and cam; FIG. 4B is a side view of the key spindle shown in FIG. 4A illustrating a portion of the camming cutout; FIG. 4C is an opposite side view of the key spindle shown in FIG. 4A illustrating a second portion of the camming cutout; FIG. 5 is a cross-sectional view of a third embodiment of a key spindle and cam; FIG. 6 is an end view of the driver shown in FIG. 1; and FIG. 7 is an end view of the hub shown in FIG. 1.

DETAILED DESCRIPTION FIG. 1 shows a door lock 10 incorporating a clutching mechanism of the present invention. An outer handle 12, preferably a lever, containing a key cylinder 28, with a tailpiece 29 extending therefrom, is connected to the outer spindle 42 which is part of the chassis 20. As shown in FIG. 2, the chassis 20 includes outer and inner hubs 40, 54. A spring cage 24, provided to hold the outer lever 12 in a horizontal position, is attached to the outer hub 24 and retained by castle nut 34. Spacer 36 provides the correct spacing of the spring cage 24 relative to outer lever 12 and outer hub 24. The preferred spring cage 24 is described in Canadian patent application no. 2177550, published December 1, 1996. Flats 41 on outer hub 40 interact with corre- sponding flats (not shown) in spring cage 24 to prevent the spring cage 24 from rotating relative to chassis 20. An outer driver 32 is keyed to lever 12. The outer driver 32 contains two notches 79 (shown in FIG. 6) which connect to two protrusions on a spring drive plate (not shown) in the spring cage 24. The spring drive plate transmits spring force from the spring cage 24 through the outer driver 32 to the outer lever 12 to hold the lever in a

horizontal position when the outer lever 12 has been unclutched from the latch retractor 46. Outer lever 12 is also keyed to an outer spindle 42. Therefor, when the outer lever 12 is turned, the outer spindle 42 is also turned. A rose 26 and driver cap 30 are provided as decorative covers to cover the spring cage 24.

The outer driver 32 has two opposed stops 75 (shown in FIG.

6) extending outwardly from the outer driver 32 towards the outer hub 40. Outer hub 40 has two opposed stops 77 (shown in FIG. 7) extending outwardly from the outer hub 40 towards the outer driver 32. As the outer lever 12 is rotated, the outer driver 32 also rotates and the stops 75, 77, known as "hard stops", interact with one another to limit the rotation of the outer lever 12 relative to the chassis 20 to slightly less than 60°. Force from further rotation of the outer lever 12 is imposed on the outer hub 40 and, unless a component of the lock fails, no further force from rotating the outer lever 12 is imposed on either the outer spindle 42 or the key spindle 44.

An inner handle 14, preferably a lever, is keyed to an inner spindle 52, which is part of chassis 20. A second spring cage 24, attached by castle nut 34 to inner hub 54, is provided to hold inner handle 14 in a horizontal position. An inner driver 38 is keyed to the second spring cage 24 in the same manner as outer handle 12 is keyed to the first spring cage 24. In some embodi- ments, push button assembly 22 is provided to provide locking capability from the inner side of lock 10.

Chassis 20, shown in FIG. 2, includes both a latch retracting mechanism and the clutching mechanism of the present invention.

Starting from the middle of chassis 20, a latch retracting mechanism is provided which includes a latch slide 46 which is biased in a latched position by slide springs 49 retained by spring seat 50. In the embodiment shown in FIG. 2, a slide catch 47 and catch spring 48 are provided which co-operate with push button assembly 22. In embodiments which do not use a push button assembly, the slide catch and catch spring are not provided. The

interior end of the inner spindle 52 includes two latch scoops 45 which interact with corresponding latch scoops 91 on latch slide 46. When inner handle 14 is turned, inner spindle 52, which is keyed to the inner handle 14, also turns. The latch scoops 45 interact with latch scoops 91 retracting latch slide 46 and thereby retracting the lock latch (not shown). When inner handle 14 is released, spring cage 24 returns the inner handle 14 to a horizon- tal or home position, the latch scoops 45 rotate back to a neutral position, and slide springs 49 return latch slide 46 and the lock latch to a latched position. A housing 56 is provided to enclose the components of the chassis 20.

Contrary to the design of the inner spindle 52, the outer spindle 42 does not contain any latch scoops. A key spindle 44 fits within outer spindle 42. Key spindle 44 is keyed to outer spindle 42 by a dog arm 66 which fits into slot 43 in outer spindle 42. With dog arm 66 engaging the outer spindle 42, the key spindle 44 is keyed to the outer spindle 42. Rotating outer handle 12 rotates the outer spindle 42 which in turn rotates key spindle 44.

Key spindle 44 has two latch scoops 45 at its interior end. Latch scoops 45 interact with latch scoops (not shown) on latch slide 46 causing latch slide 46 to retract thereby retracting the door latch. When outer handle 12 is released, spring cage 24, through outer driver 32, returns the outer handle 12 to a horizontal or home position and thereby causes outer spindle 42 and key spindle 44 to rotate to their neutral positions. Latch springs 49 bias latch slide 46 and door latch to a latched position.

Key spindle 44 includes a cam mechanism for linearly moving the dog arm 66 between a clutched (or unlocked) position where key spindle 44 and outer spindle 42 are keyed together and an un- clutched (or locked) position where the outer spindle, and the attached outer lever 12, can rotate about 60° without rotating the key spindle 44. FIGS. 3, 3A and 3B show the cam mechanism from the embodiment shown in FIGS. 1 and 2 (known as the office and entry functions). FIGS. 4, 4A, 4B and 4C and 5 show the cam mechanisms from two additional embodiments of the present invention.

The key spindle 44 has a T-shaped slot 70 in the end proximate the latch scoops 45. The dog arm 66 moves linearly within the leg 70a (clutched position) of the T-slot 70. When the dog arm 66 has been moved by the cam mechanism to the circumferentially extending head 70b of the T-slot 70, the length of the head 70b (unclutched position) permits about 60° of rotational movement of the outer spindle 42 and outer handle 12, relative to the key spindle 44.

The key spindle 44 shown in FIGS. 3, 3A and 3B consists of a tubular member with latch scoops 45 at one end thereof. Positioned within the tubular member is a rotatable and axially moveable tubular plug bushing 67. At the end of the plug bushing 67, adjacent the latch scoops 45, a dogging member 64 is attached.

Preferably, the dogging member 64 is rotatable relative to the plug bushing 67. Attached to the opposite end of the plug bushing 67 is a cam pin 60. The plug bushing 67 fits within tubular plug stem 68 which is biased by spring 69 towards the latch scoop end of the key spindle 44. The plug stem 68 contains a lost motion slot 95 through which a head end of cam pin 60 extends. The key spindle 44 has a cutout 62 which the head of cam pin 60 engages. The cutout 62 shown in FIGS. 2 and 3A is a square. As shown in FIGS.

3A and 3B, the plug stem 68 interior aperture 72 has a bow-tie shape. The tailpiece 29 of key cylinder 28 fits into bow-tie aperture 72. The bow-tie aperture shape in combination with the lost motion slot 95 provides a lost motion connection between the outer handle 12 via tailpiece 29 and key spindle 44. This lost motion connection provides sufficient lost motion between the tailpiece 72 and the key spindle 44 to prevent the key spindle 44 from moving when the outer handle 12 is turned while the dog arm 66 is in the unclutched position, and therefor prevents the latch scoops 45 from engaging the latch slide 46, prior to the hard stops on the outer driver 32 and the outer hub 40 engaging one another thereby preventing further movement of the outer lever 12.

In operation, the lock 10 with the key spindle 44 and cam mechanism shown in FIGS. 3, 3A and 3B, is locked using the push button assembly 22. The plunger bar 22a of the push button 22

engages the plug bushing 67. Pushing the push button 22, causes the plunger bar 22a to move the plug bushing 67 against spring 69 to move the dog arm 66 towards outer lever 12 thereby placing dog arm 66 in the circumferentially extending head slot 70a of the key spindle T-slot 70. With the dog arm 66 in the head slot 70a, the outer handle 12 can be rotated about 60° without rotating the key spindle 44. This is the unclutched condition of the lock 10. The hard stops 75, 77, described above, on the outer driver 32 and the outer hub 40 prevent the outer handle 12 from being rotated far enough to cause the dog arm 66 to engage the end of the head slot 70a. When the push button 22 is pushed, notches 22b on the plunger bar 22a engage the spring biased slide catch 47 which prevents the plunger bar 22a, and there for, the dog arm 66 from being moved back to their original (clutched) positions by spring 69. To unlock lock 10, the key cylinder 28 is operated by the key (not shown).

When the key cylinder has been turned approximately 60° (this takes up the lost motion between the tailpiece 29 and the bow-tie aperture 72), the plug stem 68 is turned by the tailpiece. The plug stem 68 turns until cam pin 60 engages an edge of cutout 62 at which point the key spindle 44 begins to turn, thereby turning latch scoops 45 which causes the latch slide 46 to retract to unlatch the latch. As latch slide 46 retracts, slide catch 47 also retracts releasing push button plunger bar 22a. Spring 69 then biases the cam mechanism including plug stem 68 and dog arm 66 to the clutched position where dog arm 66 is positioned in the leg 70a of the T-slot 70, thereby clutching the outer handle 12 and outer spindle 43 to key spindle 44 to allow the outer handle 12 to operate the lock 10. In summary, the push button 22 is used to lock the lock 10 and place lock 10 in an unclutched condition and the key cylinder 28 is used to unlock the lock and release the push button 22. In the embodiment shown in FIG. 1, the push button assembly 22 further includes a detent position which, when the push button 22 is pushed and turned, holds the push button 22 in the clutched position. When the push button 22 has been turned, the key cylinder 28 is used to operate the lock 10, but does not release the push button 22 from the clutched condition, i.e., movement of the catch slide 47 does not release the plunger bar

22a. To restore the lock 10 to the clutched condition, it necessary to push and turn the push button 22 to release the push button 22 from the detent position. Once the push button 22 has been released from the detent position, spring 69 biases the push button 22 and the dog arm 66 to the clutched position allowing the outer handle 12 to operate the lock 10. In a second embodiment of push button assembly 22 (not shown), the push button assembly 22 does not have a detent function.

A second embodiment of the cam mechanism (known as the class room function) is shown in FIGS. 4A, 4B and 4C. No push button 22 is provided when the class room function cam mechanism is used.

The key spindle 44 is provided with a ramped cutout 62 as shown in FIGS. 4B and 4C. The first portion of cutout 62 is a circumfer- entially extending slot 62a which extends into a ramped portion 62b. When lock 10, with classroom function, is locked, key cylinder 28 is operated to turn (counterclockwise when looking towards the chassis) tailpiece 29 which in turn engages plug bushing 67. After the lost motion of the bow-tie aperture 72 is taken up, the plug bushing 67 begins to turn. Once the lost motion of the plug stem lost motion slot 95 is taken up, the cam pin 60 begins to turn. The cam pin 60 follows the wall (closest to latch scoops 45) of the ramped portion 62b and begins to move away from the latch scoops 45 causing the plug stem 68 and attached dogging member 64 to move away from the latch scoops thereby moving the dog arm 66 from the clutched position where the dog arm 66 is in the leg 70a of the T-slot 70 to the unclutched position where the dog arm 66 is in the head 70b of the T-slot 70. At this point, the cam pin 60 is in the slot portion 62a which retains the dog arm 66 in the clutched position.

To unlock the lock 10, the key cylinder 28 is operated to turn tailpiece 29 clockwise which, after the lost motion of the bow-tie aperture 72 is taken up, begins to turn plug stem 68. After the lost motion between cam pin 60 and lost motion slot 95 is taken up, the cam pin 60 begins to move and follow the wall of cutout 62.

When cam pin 60 reaches the ramped portion 62b, spring 69 causes

the cam pin 60 along with plug stem 68 and dog arm 66 to move towards the latch scoops 45 thereby moving dog arm 66 to the leg 70a of T-slot 70, the clutched position of lock 10. In summary, when the key cylinder 28 is operated to lock lock 10, the cam mechanism drives the dog arm 66 to the unclutched position where operation of outer lever 12 does not rotate key spindle 44 to unlatch the latch. When the key cylinder is operated to unlock lock 10, the cam mechanism moves the dog arm 66 to the clutched position where the outer handle 12 does rotate key spindle 44.

A third embodiment of the cam mechanism (known as the storeroom function) is shown in FIG. 5. In this embodiment, no push button assembly 22 is used. The cam mechanism for the storeroom function is similar to the cam mechanism for the entry function, described above and shown in FIGS. 3, 3A and 3B, except that the dogging member 64 has no dog arm 66. Therefor, in the storeroom function, lock 10 is always unclutched, i.e., outer lever 12 is never connected to, and does not operate, key spindle 44.

Key cylinder 28 is operated to rotate tailpiece 29 which in turn, after taking up lost motion through bow-tie aperture 72 and lost motion slot 95, rotates key spindle 44 to operate latch slide 46.

Returning the key cylinder 28 to its normal position and removal of the key returns the storeroom function lock to the latched condition.