MULTI-PIECE PLUG ASSEMBLY FOR A CYLINDER LOCK

BACKGROUND OF THE INVENTION

The present invention relates to a lock assembly, and more particularly to an inexpensively manufactured multi-piece plug assembly.

Numerous types of conventional lock assemblies are utilized for various applications. Some door locksets include a cylinder lock which is typically located in the door operator, such as a knob, or within a guard collar of a deadlock. Such a cylinder lock includes a cylinder body which is formed with a cylindrical opening for receipt of a cylindrically shaped plug for rotation therein. The cylinder body and plug are each formed with a plurality of alignable pin chambers which receive and support sets of spring-biased tumbler pin sets. Normally, various pins overlap a juncture line between adjacent facing surfaces of the cylinder body and the plug to prevent the plug from rotating relative to the cylinder body. This juncture line is referred to as "the shear line." The plug is formed with a key slot which communicates with the pin chambers so that portions of the tumbler pins extend into the key slot. When an appropriate key is inserted into the slot, bits on the key adjust the position of the tumbler pins so that upper driver pins and lower pins of the pin sets within each pin chamber are moved to locate the interface between the lower pins and the driver pins at the shear line. The shear line is then clear and the plug can be rotated within the opening of the cylindrical body to permit rotation of a driving member and subsequent activation of the lock. Disadvantageously, the plug may be relatively difficult to manufacture due to the exacting tolerances of the multitude of pin chambers and the keyway which is formed therein. Typically, the plug is cast as a cylinder with the keyway formed therein. Then, the multiple of pin chambers are machined into the plug as a secondary operation. Although effective, this manufacturing process is relatively expensive due to the secondary machine operations.

Accordingly, it is desirable to provide a cylinder lock plug which may be manufactured in an economical manner yet maintain the exacting tolerances required for effective operation.

SUMMARY OF THE INVENTION

A cylinder lock assembly according to the present invention includes a cylinder body and a plug assembly which is manufactured in a multiple of pieces. The plug assembly include a plug body and a plug insert mountable to the plug body. The plug body and plug insert are manufactured as metallic cast components.

The plug body defines a plug insert opening to receive the plug insert from a direction generally transverse to a longitudinal axis. The plug insert opening is generally L- shaped in cross-section to receive the plug insert which is correspondingly shaped. The plug insert includes a plug outer portion which defines an arcuate outer surface which corresponds with the outer circumference of the plug body when the plug insert is mounted therein. A plug pin chamber portion extends generally transverse to the plug outer portion to define a multiple of tumbler pin chambers in their entirety. The multiple of tumbler pin chambers intersect a plug keyway portion cast within the plug pin chamber portion along the longitudinal axis. The plug insert is shaped to facilitate casting as a single component. Applicant has cast plug inserts which do not require secondary machining operations, yet provide tumbler pin chambers to tolerances which are tighter than those having heretofore machined chambers. Such secondary operation avoidance significantly facilitates inexpensive manufacture as each of the plug body and the plug insert need only be cast in a single operation. Furthermore, casting minimizes the requirements for proper indexing of machining fixtures which still further reduces manufacturing expense through yield loss decrease.

The present invention therefore provides a cylinder lock plug which may be manufactured in an economical manner yet maintain the exacting tolerances required for effective operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:

Figure IA is an exploded perspective view of a lock assembly for use with the present invention;

Figure IB is a sectional view of the lock assembly of Figure IA taken along the longitudinal axis;

Figure 2A is an exploded perspective view of a plug assembly according to the present invention;

Figure 2B is a sectional view of the plug assembly of Figure 2A taken along line 2b-2B in Figure 2A;

Figure 2C is a perspective bottom view of a plug insert of the plug assembly of Figure

2A;

Figure 3 is a front perspective view of a lock assembly with the plug assembly of the preset invention installed into a lock cylinder; and

Figure 4 is a rear perspective view of an assembled plug assembly according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Figure IA illustrates a general exploded perspective view of a cylinder lock 10. The cylinder lock 10 generally includes a cylinder body 12 and a plug assembly 14. The plug assembly 14 is preferably manufactured in two pieces which include a plug body 16A and a plug insert 16B which is mountable within the plug body 16 A. The body 12 and the plug assembly 14 are preferably manufactured as metallic cast components. It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit from the instant invention. Once assembled, the plug assembly 14 is inserted into a cylindrical opening 17 of the cylinder body 12 so that each of a multiple of plug tumbler pin chambers 18 within the

plug assembly 14 are aligned with a respective multiple of body tumbler pin chambers 20 within the cylinder body 12 (Figure IB). A pin set 21 including a bottom pin 22, a top pin 24 and a spring 26 are positioned within each of the aligned chambers 18, 20. A cover 28 is positioned over the chambers 20 to retain the pin sets 21 therein. A clip 30 is engaged with an inward segment 32 of the plug assembly 14 to rotationally retain the plug assembly 14 within the cylinder body 12 (Figure IB).

An actuating member 34 is located adjacent or within the inward segment 32 of the plug to engage a latch actuating assembly (not shown) and subsequent retraction or extension of a bolt or latch to activate the lock in a conventional manner which need not be described in detail herein.

Referring to Figure IB, the plug assembly 14 defines a keyway 36 along a longitudinal axis A of the plug assembly 14 to permit insertion of a key which aligns the pin sets 21 relative a shear line such that the plug assembly 14 can be rotated relative the cylinder body 12 to actuate the lock. Operation of the key to pin arrangement may take various conventional forms and need not be described in detail herein.

Referring to Figures 2A and 2B, the plug body 16A includes a plug insert opening 38 to receive the plug insert 16B from a direction generally transverse to the longitudinal axis A. The plug insert opening 38 is formed between a plug body outward segment 40 and the inward segment 32. The plug body outward segment 40 defines a keyway opening 42 (Figure 3) which directs a key into the plug body keyway portion 36 A. The plug body keyway portion 36A connects the keyway opening 42 in the plug body outward segment 40 with the plug insert opening 38. Preferably, the plug insert opening 38 is generally L- shaped in cross-section (Figure 2B) to receive the plug insert 16B which is correspondingly shaped. Notably, the plug body 16A does not include separate plug chambers and is of a relatively uncomplicated tubular shape which readily facilitates molding in a single operation.

The plug insert 16B includes a plug outer portion 44 which defines an arcuate outer surface 45 which corresponds with the outer circumference 46 of the plug body 16A when the plug insert 16B is mounted therein (Figure 4). That is, the outer surface 45 of the plug insert 16B completes the outer cylindrical surface of the plug body 16 A. The

arcuate outer surface 45 includes the outermost openings 18a of the tumbler pin chambers 18 to interface with and receive the pins sets 21 (Figure IA) from the body tumbler pin chambers 20 within the plug cylinder 14.

The arcuate outer surface 45 may include pattern key "PK" ball receiving pockets 47 adjacent the outermost openings 18a to receive the PK balls as generally understood. The PK pockets 47 are preferably located in a segment of the plug outer portion 44 which extends in a cantilever manner from a plug pin chamber portion 48. That is, the multiple of tumbler pin chambers 18 extend through the arcuate outer surface 45 of the plug outer portion 44 and through the plug pin chamber portion 48 while the PK pockets are recesses in the plug outer portion 44 but do not extend through the plug outer portion 44 or into plug pin chamber portion 48.

Generally transverse to the outer plug portion 44, is the plug pin chamber portion 48 such that the plug insert 16B is of a generally "L" shape which corresponds with the plug insert opening 38 (Figure 2B). In other words, the plug pin chamber portion 48 is the long leg of the "L" shape while the plug outer portion 44 includes the arcuate outer surface 45 and forms the short leg of the "L" shape.

The plug pin chamber portion 48 defines the multiple of tumbler pin chambers 18 in their entirety. That is, the entire bore of each tumbler pin chamber portions 48 is located in the plug insert 16B. The plug pin chamber portion 48 extends along the longitudinal axis A. The multiple of tumbler pin chambers 18 each includes a tumbler pin chamber axis T that is transverse to and intersects the longitudinal axis A (also illustrated in Figure IB). The multiple of tumbler pin chambers 18 intersect the plug keyway portion 36B formed within the plug pin chamber portion 48 along the longitudinal axis A. The keyway portion 36B is preferably open along the longitudinal length of the plug pin chamber portion 48 on a bottom side 50 thereof to form a general U-shaped slot with the tumbler pin chambers 18 formed at intervals there along (Figure 2C). The open bottom side 50 of the plug pin chamber 48 aligns with a slot 36s formed in the plug body 16A when the plug insert 16B is located therein. The slot 36S preferably forms another portion of the keyway.

The plug insert 16B preferably defines the multiple of tumbler pin chambers 18 and the plug keyway portion 36B in an arrangement which facilitates casting as a single component. In fact, Applicant has cast plug inserts 16B which do not require secondary machining operations, yet provide tumbler pin chambers 18 to dimensional tolerances which are tighter than those with heretofore machined chambers. Such secondary operation avoidance significantly facilitates inexpensive manufacture as each of the plug body 16A and the plug insert 16B need only be cast in a single operation. Furthermore, casting minimizes the requirements for proper indexing of machining fixtures which still further reduces manufacturing expense through yield loss decrease. It should be understood that relative positional terms such as "forward," "aft," "upper," "lower," "above," "below," and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting. Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention. The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.