Lock Mechanism

Abstract

A lock incorporating two locking positions and formed by a body with a key plug and cylinder coaxially rotatable therein. Locking pins in the body plug and cylinder adapted to be aligned by one key so as not to transverse the line of junction between the cylinder and key plug and with another key so as not to transverse the line of junction between the cylinder and body of the lock. A further pin within a further hole in the cylinder in one position locks the cylinder and key plug together.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to locks. More particularly, the present invention relates to locking mechanisms having two separate and distinct locking positions requiring two separate and distinct releasing means (keys) one of which is operable in both locking positions.

2. Description of Prior Art

Pin tumbler locks are used for a multitude of applications including automobiles, various doors and drawers, etc. Generally, these locks operate on the principle of aligning the ends of the pins and tumblers with the line of demarcation between the key plug and tumbler carrier in the housing of the lock to release the key plug for rotation.

It is sometimes desirable to have two degrees of locking safety for a given installation, for example, it is sometimes desirable to maintain the area locked while permitting access by certain people or a specific person during limited periods of time without permitting complete access for this person at any time and without leaving the area unlocked. No suitable device for accomplishing this other than the use of two separate and distinct locks is presently available.

SUMMARY OF INVENTION

It is thus the main object of the present invention to provide a single lock structure operable by a pair of different keys, one of which is only operable to unlock the lock when it is in one of the locking positions.

Broadly, the present invention relates to a lock including a key plug concentric with and rotatable in an intermediate cylinder which in turn is rotatable in the body of the lock, there being a pair of rows of individual pushdown tumblers arranged for movement in cylindrical holes extending substantially radially of the axis of rotation of the plug and intermediate cylinder. A set of key tumblers are positioned in suitable holes in the key plug and intermediate cylinder and are adapted to cooperate with the pushdown tumblers to be biased into a locking position preventing relative rotation of the plug, intermediate cylinder and body member. The tumbler pins, being adapted, upon insertion of one key, have to be aligned to permit relative rotation of the plug and intermediate cylinder while locking the intermediate cylinder and body of the lock together and with a second key to have the ends of the tumblers aligned with the line of juncture between the intermediate cylinder and the body of the lock to permit relative movement between the intermediate cylinder and the body of the lock while locking the intermediate cylinder and tumbler together.

BRIEF DESCRIPTION OF DRAWINGS

Further features, objects and advantages will be evident from the following detailed description of a preferred embodiment of the present invention taken in conjunction with the accompanying drawings in which:

FIG. 1 is a section along the line 1-1 of FIG. 2 illustrating one set of pushdown tumblers and key tumblers together with the key plug and intermediate cylinder of the present invention;

FIG. 2 is a partial section along the line 2-2 of FIG. 1;

FIG. 3 is a front view illustrating the key slot of the present invention;

FIG. 3a is a partial section of the key slot with a key being inserted;

FIG. 4 is a view similar to FIG. 1 but showing the effect of the secondary key on the system;

FIG. 5 is a view similar to FIG. 4 but with the master key in operative position;

FIG. 6 is a view along the line 6-6 of FIG. 7 showing the intermediate cylinder and plug aligned with the second locking position of the locking mechanism and having a secondary key inserted;

FIG. 7 is a partial section along the line 7-7 of FIG. 6 illustrating the locking detent in position;

FIG. 8 illustrates a modification of the detent mechanism which prevents relative rotation between the plug and cylinder and cylinder and body of more than 360.degree..

DESCRIPTION OF PREFERRED EMBODIMENTS

In the illustrated arrangements, the throw bar or bars or switches actuated by turning of the keys in the lock have not been illustrated. Any suitable and/or conventional connecting means between the key plug and the element or elements to be locked may be provided.

As shown in the figures, the lock 10 has a main body 12 which incorporates a pair of tumbler receptacles 14a and 14b (see FIGS. 2 and 7). Rotatably mounted in the body portion 12 is an intermediate cylinder 16 and rotatably mounted within and concentric with the cylinder 16 is a key plug 18. The intermediate cylinder 16 and key plug 18 are retained in the body 12 by means of a retainer end washer 19 which is bolted or otherwise secured to the plug 18, retaining both intermediate cylinder and plug from moving axially apart from body 12. The retainer washer 19 may serve yet another function, namely to retain the means connecting the key plug to a conventional locking mechanism.

Each of the retainers 14a and 14b has a plurality of guide holes which will be described first in relation to retainer 14b. As shown in FIG. 1, retainer 14b includes a plurality of guide holes 20, each containing a pushdown tumbler pin 22 which is biased toward the intermediate cylinder 16 by means of springs 24 trapped within the guide holes 20 by a cover plate 26. The guide holes 20 extend substantially radially of the axes of rotation of the key plug 18 and intermediate cylinder 16. The guide holes and equivalent parts in the retainer 14a for convenience have been indicated with the same reference numbers as those described above with respect to retainer 14b but followed by the letter a (see FIG. 6).

The retainer 14b is provided with one supplemental radial guide hole 20' which in the illustrated arrangement is positioned at the rear of the lock 10. This guide hole 20' contains a pushdown tumbler pin 22' which is biased toward the intermediate cylinder 16 by means of a spring 24' that is stronger than the individual springs 24 and 24a described hereinabove.

The intermediate cylinder and the key plug 18 are each provided with a plurality of radial guide holes 28 and 30 respectively. Suitable key end tumbler pins 32 and in some cases in the illustrated arrangement key end tumbler pins 32 and intermediate tumbler pins 34 are received within the guide holes 28 and 30. The intermediate pins 34 are not essential but are preferred to permit a maximum variation in key shapes and easy differentiation in shape between the master key A and secondary key B as will be more evident from the description hereinbelow. Each guide hole 20 has corresponding guide holes 28 and 30 in the intermediate cylinder and key plug and suitable pins 22, 32 and 34 are retained within these holes to operate the locking mechanism. The holes 20, 20a, 28 and 30 are of substantially the same cross-sectional shape and size and the pins 22, 32 and 34 can slide axially in all these holes.

The intermediate cylinder 16 is provided with a further radial hole 28' adapted to align with the hole 20' in the retainer 14b. A locking pin or detent pin 34' is received within the hole 22' and is adapted to project into a locking blind hole or pit 36 formed in the key plug 18 (see FIG. 4). The pin 34' functions as a detent when the intermediate cylinder 16 has its holes 28 in alignment with the holes 20 in the retainer 14b and as a locking pin to hold the holes 28 and 30 aligned when the holes 28 and 20 are not aligned. As will be described in more detail hereinbelow, the pin 34' must be slightly longer than the radial thickness of the intermediate cylinder 16, i.e. the length of the slot or hole 28'. The pin 22' is adapted to cooperate with a blind hole or pit 21 in the cylinder 16 to function as a detent pin indicating alignment of the cylinder with the retainer 14a (see FIG. 7).

The key plug 18 has a conventional key slot 38 and is provided with a rib 40 or other conventional means to hold the pins 22, 34 and 32 in a position higher in level than key slope tip z (see FIGS. 1, 3 and 3a).

The operation of the lock will now be described with respect to FIGS. 4 to 7 inclusive.

Assuming that the lock is in position with the holes 28 and 30 aligned with the holes 20 in the retainer 14b, i.e. in a position where the secondary key B is operable, insertion of the key B aligns the ends of the tumblers with the junction or line of demarcation 42 between the intermediate cylinder 16 and the key plug 18 with some of the pins 22 or 34 traversing the junction line 44 between the cylinder 16 and body 12 (see FIG. 4). It will be noted that the tumbler 34' is retained within the blind hole or pit 36 and functions as a detent to indicate alignment of the holes 20, 28 and 30 but does not prevent relative rotation of the plug 18 to the cylinder 16. Thus, with the key B in position as shown in FIG. 4, rotation of this key B will turn the key plug 18 since there are no pins 22, 32 or 34 projecting across the junction line 42 and the detent pin 34' will simply be forced out of the hole 36 by compressing the spring 24'. Rotation of the key plug 18 locks or unlocks the bolt or the like connected with the plug 18 in the conventional manner.

When it is desired to lock the lock 10 so that the key B will be inoperative, the key A must be inserted into the slot 38 as shown in FIG. 5. This aligns the ends of the tumblers with the junction or line or demarcation 44 between the intermediate cylinder 16 and the body 12 (there being no tumbler pins traversing line 44) and permits relative rotation of the intermediate cylinder 16 in the body 12. The key plug 18 is locked to and turns with the cylinder 16 as some of the pins 32 or 34 traverse the line of junction 42 and the pin 34' is trapped in the hole 28' and blind hole or pit 36. Thus, turning the key A turns both the cylinder 16 and the key plug 18 and thus permits opening of the lock or turning of the lock into alignment with the retainer 14a.

If desired, the key A can rotate the cylinder 16 and plug 18 to the position shown in FIG. 5 and wherein the holes 28 and 30 are aligned with the holes 20a in the receptacle 14a. With the cylinder 16 and plug 18 in the position shown in FIG. 6, the secondary key B cannot be substituted for key A to open the lock 10. As shown in this figure, the key B aligns the tumblers 22a, 32 or 34 so that none traverse the line of juncture 42. However, the pin 34' is trapped in the hole 28' and blind hole or pit 36 thereby locking the plug 18 to the cylinder 16 and preventing relative movement therebetween. Rotation of the cylinder 16 and plug 18 together within the body 12 is prevented by pins 22a, etc., traversing the junction line 44. Thus, in the position shown in FIG. 6 with the holes in the key plug 18 and intermediate cylinder 16 aligned with the holes 20a in the receptacle 14a, operation by secondary key B is prevented.

From the above, it is apparent that the key A will operate the lock 10 regardless of whether the holes in the intermediate cylinder and plug are aligned with the holes in the receptacle 14a or 14b while the key B can only operate in the latter position.

FIG. 8 illustrates a modification of the blind holes or pits 21 and 36 adapted to limit rotation of the cylinder 16 relative to the body 12 and to less than 360.degree. and relative rotational movement between the plug 18 and cylinder 16 to less than 360.degree.. As shown, the cylinder 16 and plug 18 are provided with locking holes 21a and 21b and 36a and 36b respectively with a stop 23 and 37 respectively positioned therebetween to limit the rotational movement of the cylinder 16 and key plug 18.

Modifications may be made without departing from the spirit of the invention as defined in the appended claims.

Claims

I claim:

1. A lock including a body having locking positions, an intermediate cylinder rotatably mounted in said body and a key plug rotatably mounted in said cylinder, said key plug and cylinder being coaxially mounted for rotation about an axes, a plurality of radial holes in said plug and cylinder and in said body in said locking positions, tumbler pins in said holes, means biasing said tumbler pins towards said plug in said locking position, said holes in said plug being alignable with said holes in said cylinder and with said holes in said body in each of said locking positions, a further radial hole in said cylinder and a blind hole in said plug, a locking pin in said further hole, said locking pin being adapted to cooperate with said blind hole in said plug.

2. A lock as defined in claim 1, further comprising a supplemental hole in said body in one of said locking positions, said supplemental hole containing a pin, means biasing said pin towards said cylinder, said blind hole and said further hole being alignable with said supplemental hole in said one locking position whereby said pin and said locking pin cooperate to form a detent biased into said blind hole for aligning said plug and cylinder in said one position.

3. A lock as defined in claim 2, wherein said locking pin is trapped in said further hole and said blind hole thereby locking said key plug and cylinder together when said plug and cylinder are simultaneously moved from said one position.

4. A lock as defined in claim 3, further comprising a detent hole in said cylinder, said detent hole being alignable with said pin in said supplemental hole in another of said locking positions.

5. A lock as defined in claim 1, wherein said tumbler pins include pushdown pins, intermediate pins and key end pins.

6. A lock as defined in claim 3, wherein said tumbler pins include pushdown pins, intermediate pins and key end pins.

7. A lock as defined in claim 4, wherein said tumbler pins include pushdown pins, intermediate pins and key end pins.

8. A lock as defined in claim 4, wherein one key is adapted to operate said lock to align said tumbler pins so that none traverse a junction line between said plug and cylinder, and wherein another key is adapted to operate said lock to align said tumbler pins so that none of said tumbler pins traverse a line of junction between said cylinder and body.

9. A lock as defined in claim 7, wherein one key is adapted to operate said lock to align said tumbler pins so that none traverse a junction line between said plug and cylinder, and wherein another key is adapted to operate said lock to align said tumbler pins so that none of said tumbler pins traverse a line of junction between said cylinder and body.

10. A lock as defined in claim 9, wherein said holes are arranged in rows in said key plug, said cylinder and said locking positions in said body.