BACKGROUND OF THE INVENTION Portable cabinets, such as those used to transport beverages and foods in airplanes, are well known and familiar. Generally these cabinets have a door which may be closed by a cam-actuated mechanism which, by the turn of a handle, selectively inserts bolts into recesses in the frame of the cabinet. Presently, any lock used to lock the cabinet door comprises a lock placed on or in the vicinity of the handle, much like any common door lock.

SUMMARY OF THE INVENTION The present invention seeks to provide a locking system for portable cabinets which provides improved security and locking integrity.

There is thus provided in accordance with a preferred embodiment of the present invention, lock apparatus for a door of a cabinet, including a bolt attached to a rotatable cam, the bolt being arranged for generally linear movement into and out of a first recess in a frame of a door of a cabinet upon suitable rotation of the cam, a stub extending generally perpendicularly from a surface of the cam, and a key-operated cylinder lock having a rotatable plug and operable to bring a locking tongue into and out of locking engagement with a second recess in the frame of the cabinet, the locking tongue, when in locking engagement with the second recess, being positioned to prevent movement of the stub past the locking tongue, thereby to prevent rotation of the cam.

In accordance with a preferred embodiment of the present invention, the rotatable cam and the rotatable plug rotate generally about a common axis. Alternatively or additionally, the rotatable cam and the rotatable plug rotate generally about different axes.

Additionally in accordance with a preferred embodiment of the present invention, the locking tongue includes a hooked member which may be lockingly engaged with the stub.

Further in accordance with a preferred embodiment of the present invention, there is provided a locking element which abuts against an upper end of the linkage bar, and a locking mechanism which is operative to move a locking rod into and out of locking engagement with an upper end of the locking element through a pair of holes formed in the cabinet and the door. The locking mechanism may be a push lock.

There is also provided in accordance with a preferred embodiment of the present invention, a method for retrofitting a lock apparatus for a door of a cabinet, the lock apparatus including a bolt attached to a rotatable cam, the bolt being arranged for generally linear movement into and out of a first recess in a frame of a door of a cabinet upon suitable rotation of the cam, the cam being rotatable by means of a handle linked thereto with a linkage bar, the method including attaching a stub to the cam such that the stub extends generally perpendicularly from a surface of the cam, and installing in propinquity to the cam a key- operated cylinder lock having a rotatable plug and operable to bring a locking tongue into and out of locking engagement with a second recess in the frame of the cabinet, the locking tongue, when in locking engagement with the second recess, being positioned to prevent movement of the stub past the locking tongue, thereby to prevent rotation of the cam.

There is also provided in accordance with a preferred embodiment of the present invention, a method for retrofitting a lock apparatus for a door of a cabinet, the lock apparatus including a bolt attached to a rotatable cam, the bolt being arranged for generally linear movement into and out of a first recess in a frame of a door of a cabinet upon suitable rotation of the cam, the cam being rotatable by means of a handle linked thereto with a linkage bar, the method including installing on the door a locking element which abuts against an upper end of the linkage bar, and installing a locking mechanism on the cabinet which is operative to move a locking rod into and out of locking engagement with an upper end of the locking element through a pair of holes formed in the cabinet and the door.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: Fig. 1 is a simplified pictorial illustration of lock apparatus for a door of a cabinet, constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 2 is a simplified pictorial illustration of lock apparatus of Fig. 1, as viewed from inside the cabinet, no cylinder lock being shown for the sake of clarity; Figs. 3 and 4 are simplified pictorial illustrations of lock apparatus of Fig. 1, as viewed from inside the cabinet, with a cylinder lock and locking tongue in unlocked and locked orientations, respectively, and wherein a plug of the cylinder lock and a rotatable cam are arranged for rotation generally about the same axis;

Figs. 5 and 6 are simplified pictorial illustrations of lock apparatus of Fig. 1, as viewed from inside the cabinet, with a cylinder lock and locking tongue in unlocked and locked orientations, respectively, and wherein a plug of the cylinder lock and a rotatable cam are arranged for rotation about different axes; and Fig. 7 is a simplified pictorial illustration of lock apparatus for a door of a cabinet, constructed and operative in accordance with another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Reference is now made to Fig. 1 which illustrates lock apparatus 10 for a door 12 of a cabinet 14, constructed and operative in accordance with a preferred embodiment of the present invention. Cabinet 14 may be any type of portable or non-portable cabinet, with or without shelves therein. As is known in the art, door 12 may be closed by a cam-actuated mechanism 16, described further hereinbelow with reference to Fig. 2. Unlike the prior art, lock apparatus 10 is not mounted on or in the vicinity of a handle 18, but rather is mounted on cam-actuated mechanism 16. As is described hereinbelow in greater detail, lock apparatus 10 preferably includes a cylinder lock 20 with a plug arranged for rotation generally about the same axis as a cam of cam-actuated mechanism 16, such an arrangement being designated by a reference letter"A". Alternatively or additionally, the plug of cylinder lock 20 and the cam of cam-actuated mechanism 16 may be arranged for rotation about different axes, such an arrangement being designated by a reference letter"B".

Reference is now made to Fig. 2 which illustrates lock apparatus 10, as viewed from inside cabinet 14, with cylinder lock 20 omitted for the sake of clarity. Cam-actuated mechanism 16 preferably includes a bolt 24 attached to a rotatable cam 26. A linkage bar 28 mechanically links a handle mechanism 30 associated with handle 18 to cam 26. Linkage bar 28 transfers rotation of handle 18 to rotation of cam 26. Bolt 24 is arranged for generally linear movement into and out of a first recess 32 in a frame 34 of cabinet 14 upon suitable rotation of cam 26. In accordance with a preferred embodiment of the present invention, a stub 40 extends generally perpendicularly from a surface 42 of cam 26.

Reference is now made to Figs. 3 and 4 which further illustrate-lock apparatus 10, as viewed from inside cabinet 14, corresponding to the location of reference letter"A"of Fig. 1. It is seen that key-operated cylinder lock 20 has a rotatable plug 44, and that cam 26 and plug 44 rotate generally about a common axis 46. Rotation of plug 44 about axis 46 in the direction of an arrow 48 brings a locking tongue 50 into locking engagement with a second

recess 52 in frame 34. Conversely, rotation of plug 44 about axis 46 in a direction opposite to arrow 48 brings locking tongue 50 out of locking engagement with second recess 52.

Fig. 4 illustrates locking engagement of a hooked end 54 of locking tongue 50 with second recess 52. In order to open door 12, it is necessary rotate cam 26 about axis 46 in a direction opposite to arrow 48. However, in the locked engagement of Fig. 4, locking tongue 50 is positioned to prevent rotation of cam 26 and movement of stub 40 past locking tongue 50, thereby preventing opening of door 12.

Reference is now made to Figs. 5 and 6 which illustrate an alternative embodiment of lock apparatus 10, designated as lock apparatus 60, as viewed from inside cabinet 14, corresponding to the location of reference letter"B"of Fig. 1. Lock apparatus 60 is substantially identical to lock apparatus 10, with like numerals designating like elements.

Lock apparatus 60 differs from lock apparatus 10 in that lock apparatus 60 includes a locking tongue 62 with a hooked end 64 and, in addition, a hooked member 66 which may be lockingly engaged with stub 40. It is seen that plug 44 of key-operated cylinder lock 20 rotates about an axis 68, different than axis 46. Rotation of plug 44 about axis 68 in the direction of an arrow 70 brings hooked end 64 of locking tongue 62 into locking engagement with a recess 72 in frame 34 and hooked member 66 into locking engagement with stub 40. Conversely, rotation of plug 44 about axis 68 in a direction opposite to arrow 70 brings hooked end 64 out of locking engagement with recess 72 and hooked member 66 out of locking engagement with stub 40.

Reference is now made to Fig. 7 which illustrates lock apparatus 80 for door 12 of cabinet 14, constructed and operative in accordance with another preferred embodiment of the present invention. It is appreciated that cabinet 14 may be equipped with one or both lock apparatus 10 and 80. Lock apparatus 80 preferably includes a locking element 82 which abuts against an upper end 84 of linkage bar 28. Locking element 82 is preferably assembled on door 12 and may be guided by a guide element 86. A locking mechanism 90 is preferably mounted on the top of cabinet 14 and is operative to move a locking rod 92 into and out of locking engagement with an upper end 94 of locking element 82 through a pair of holes 96 and 98 formed in cabinet 14 and door 12, respectively. Locking mechanism 90 is preferably a push lock, i. e., a cylinder lock with a spring return 100. A biasing mechanism 104, such as a coil spring, may be disposed intermediate guide element 86 and a disc 106 disposed on locking element 82. When locking mechanism 90 is in an unlocked orientation as shown in Fig. 7, biasing mechanism 104 urges locking element 82 against upper end 84.

It is appreciated that any prior art cabinet may easily retrofitted with any or all of lock apparatus 10,60 and 80.

It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.