GB2401645A

GB2401645A - Mechanical combination lock

Info

Publication number: GB2401645A
Application number: GB0409320A
Authority: GB
Inventors: Ming Chen
Original assignee: Kin Kei Hardware Ind Ltd
Current assignee: Kin Kei Hardware Ind Ltd
Priority date: 2003-04-28
Filing date: 2004-04-27
Publication date: 2004-11-17
Anticipated expiration: 2024-04-27
Also published as: GB0409320D0; GB2401645B; HK1069859A1; CN2616614Y

Abstract

A mechanical combination lock 10 for attachment to a door includes a number of pushbuttons 13 a knob spindle and a carriage 30 adapted to move upon turning of the knob spindle. The carriage 30 has a number of fixed teeth 17 each associated with one of the pushbuttons 13. A number of user-reconfigurable combination-defining tumblers 16 are each associated with a respective one of the teeth 17, each tumbler 16 has a pair of through-slots 23, 24 at opposed sides and at different levels. Each tumbler 16 moves to a down-position upon depression of its associated pushbutton 13. A catch mechanism 22 retains each tumbler in its down-position. Each tumbler 16 can be selectively reconfigured by turning to thereby present one of its through-slots to the carriage 30 such that any down-positioned tumbler 16 associated with a correct selected combination pushbutton has one of its slots aligned with its associated tooth, to thereby allow passage of that tooth 17. The carriage cannot move to allow sufficient rotation of the knob spindle to unlock the lock when of any one of the teeth strikes against a down-positioned non-combination configured tumbler.

Description

2401 645 - 1 Mechanical Combination Lock

Background of the Invention

The present invention relates to door locks. More particularly, although not exclusively, the invention relates to a mechanical push-button combination lock having an easily-changed combination.

It is known to provide combination locks for doors. Some such locks comprise an electronic keypad and therefore require wiring and/or batteries. The digital combination of such locks is changed by input to embedded software.

Mechanical combination locks are convenient for doors as there is no need to provide a source of electric power.

However, known mechanical combination locks present difficulty to the installer and/or operator when it is desired to change the factory preset combination. This is usually because small combination-defining components must be removed from the lock and rearranged or replaced with other different ones as the case may be.

Objects of the Invention It is an object of the present invention to overcome or substantially ameliorate the above disadvantage and/or more generally to provide an improved mechanical combination lock having an easily-changed combination.

Disclosure of the Invention

There is disclosed herein a mechanical combination lock, comprising: a chassis for attachment to a door, a cover securely housing the chassis, a plurality of pushbuttons extending through openings in the cover, a pivotal knob spindle mounted to the chassis, a carriage mounted to the chassis and adapted to move upon turning of the knob spindle and comprising a plurality of fixed teeth - each tooth associated with one of said pushbuttons, a plurality of user-reconfigurable combination- defining tumblers, each associated with a respective one of said teeth, each tumbler comprising a pair of through- slots at opposed sides of the tumbler and at different levels thereon, each tumbler moving to a down-position upon depression of its associated pushbutton, a catch mechanism for retaining each tumbler in it's down- position upon depression of its associated pushbutton, and re- configuration means for selectively turning each tumbler to thereby present one of its through-slots to the carriage to define the combination of the lock such that any down-positioned tumbler associated with a correct

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selected combination pushbutton has said one of its slots aligned with its associated tooth, to thereby allow passage of that tooth therethrough, and wherein the carriage cannot move to allow sufficient rotation of the knob spindle to unlock the lock when of any one of said teeth strikes against a down-positioned non-combination configured tumbler.

Preferably the carriage moves linearly along the chassis.

Preferably the lock for the comprises a plurality of pawl plates respectively interposed between each pushbutton and its associated tumbler and wherein the catch mechanism comprises a plurality of deflection springs that engage with the pawl plate.

Preferably the carriage comprises a pair of parallel bars each having said teeth thereon - the teeth of one said bar facing the teeth of the other said bar and wherein said pushbuttons are providing in two parallel linear arrays.

Preferably the deflection springs are mounted upon a common beam that is flanked by said bars.

Preferably there is provided beneath each pushbutton a return spring.

Preferably said re-configuration means comprise respective screw heads keyed to each of said tumblers.

Preferably each screw head has extending from it a spline that slides within a cavity of corresponding shape in each tumbler.

Preferably the lock further comprises a respective compression spring surrounding each spline and biasing the screw head away from the tumbler.

Preferably the knob spindle rotates a gear upon which there is mounted a pair of diametrically opposed bosses, one of which bears against the carriage depending upon the turning direction of the knob spindle.

Preferably the lock further comprises a reset pushbutton that releases the pawl plates from the catch mechanism.

Brief Descrintion of the Drawinas A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a schematic transverse crosssectional elevation of a mechanical combination lock,

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Fig. 2 is a schematic inverted illustration of a screw head, many of which are present in the lock of Fig. 1 and each used to change the combination of the lock, Fig. 3 is a schematic inverted illustration of a single tumbler, many of which are present in the lock of Fig. 1, Fig. 4 is a schematic side elevation of the screw head of Fig. 2, Fig. 5 is a schematic side elevation of the tumbler of Fig. 3, I Fig. 6 is a schematic illustration from above of the screw head of Fig. 2, Fig. 7 is a schematic view from above of the tumbler of Figs. 3 and 5, and Fig. 8 is a schematic illustration showing internal components of the lock of Fig. 1.

Description of the Preferred Embodiment

In the accompanying drawings there is depicted schematically a mechanical combination lock 10 comprising parts all made of metal. The lock 10 comprises a chassis 11 securely covered by a cover 12. These parts would be

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screwed together prior to mounting upon a door.

The lock 10 comprises a number of pushbuttons 13 extending through the cover 12. Each pushbutton would be identified by alphanumeric indicia or other symbols which can be viewed in use. The indicia might be either upon the pushbuttons or upon the cover adjacent each pushbutton. There are two linear arrays of pushbuttons 13.

Mounted within the chassis beneath each pushbutton 13 is a tumbler 16. That is, there are two linear arrays of tumblers 16 - each tumbler corresponding with one of the pushbuttons 13. Each tumbler 16 is generally cylindrical and fits both slidably and rotatably within one of numerous circular holes extending downwardly through the chassis 11 behind each pushbutton 13. Extending into the top surface of each tumbler 16 is a circular hole 18 into which the leg 19 of a pawl plate 15 extends. There is a compression pushhutton-return spring 14 beneath each pushbutton 13 that bears upon each pawl plate 15. Each pawl plate comprises a pawl 20 having an angular ramp surface.

Positioned centrally of the chassis 11 is a beam 21 having at spaced positions therealong a number of spring elements 22. Each spring element 22 engages with one of the pawls 20 upon depression of its associated pushbutton to retain the pawl plate 15 in a down-position. As each pawl plate bears downwardly upon its associated tumbler 16, the tumbler 16 is also retained in a down-position (not depicted) after its associated pushbutton is depressed.

Each tumbler 16 has a pair of slots 23 and 24 extending across it at different levels as depicted in Figs. 1 and 5. Extending into the bottom of each tumbler 16 is a non-circular recess 25 into which there extends a spline 26 of a screw head 27. The cross-sectional profile of the spline preferably matches that of the non-circular recess 25. The screw head comprises a slot 28 into which the tip of a screwdriver can be received. The screw head would include a mark 29 that indicates the orientation of the tumbler 16 within its circular hole to a locksmith or other person resetting the lock combination. There is a compression spring 33 surrounding each spline 26 biasing the tumbler 16 away from the screw head 27.

There is a sliding carriage 30 mounted within the chassis 11 and comprising a pair of parallel bars 31 and 32.

Each bar has a plurality of teeth 17 corresponding in number and spacing to each tumbler 16. The teeth 17 of one bar face the teeth 17 of the other.

Also mounted to the chassis 11 is a knob spindle 34 to which a knob or handle would be attached. The knob -it spindle when turned rotates a gear 35 that is also mounted to the chassis 11. At diametrically opposed positions of the gear 35 there is a pair of bosses 36.

Depending upon the rotation direction of the knob spindle 34 and gear 35, one of the bosses 36 will bear upon the carriage 30 to push it against a pair of return springs 37 located at the opposite end of the carriage.

Interaction of all the teeth 17 with their respective tumblers 16 determines whether or not the knob spindle 34 can be turned. It should be appreciated in this regard that there would be a standard, or customdesigned latch mechanism associated with the knob spindle 34 and when the lock is locked, the spindle 34 cannot spin and as a result, the door to which the lock is mounted cannot be opened.

In Fig. 1, the left-hand pushbutton is indicated as 13A.

This pushbutton is one of the combination pushbuttons, whereas pushbutton 13 at the right is not a combination pushbutton. This of course can be changed depending on the desired combination. Both pushbuttons 13 and 13A an their associated pawl plates and tumblers are shown pri, to depression of the pushbuttons in Fig. 1. When pushbutton 13A is depressed, the interaction of the pE plate 15 with one of the retaining spring elements 22 will retain the tumbler in a down-position against compression of spring 33. At this position, slot 2 aligned with the carriage 30 so that the nearby adjacent tooth 17 can enter the slot 23 when the carriage is moved upon manipulation of the knob spindle. The right-hand tumbler 16 has its other slot 24 aligned with the carriage 30 and therefore to 17 can enter it. Being a non-combination pushbutton, if pushbutton 13 is depressed, the part of the tumbler above the slot 24 will block passage of the tooth 17 and thereby prevent movement of carriage 30 and thereby prevent rotation of the knob spindle 34.

In order to change the combination of the lock, the screw heads 27 can be rotated throughout 180 degrees by use of a screwdriver.

Note that the order in which the combination buttons are depressed is not important. For example, if the combination is "1793", then "9317" will open the lock, ; but "93172" or "98" will not open the lock.

A reset button will release the spring elements 22 so that all of being tumblers 16 returned to the position in which they are depicted in Fig. 1.

It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, instead of providing a linearly - lD movable carriage and linear arrays of pushbuttons, the carriage could be provided as a ring about the knob spindle 34 in which case there might be provided a circular array of pushbuttons about the knob.

Claims

CLAIMS: 1. A mechanical combination lock, comprising: a chassis for

attachment to a door, a cover securely housing the chassis, a plurality of pushbuttons extending through openings in the cover, a pivotal knob spindle mounted to the chassis, a carriage mounted to the chassis and adapted to move upon turning of the knob spindle and comprising a plurality of fixed teeth - each tooth associated with one of said pushbuttons, a plurality of user-reconfigurable combination- defining tumblers, each associated with a respective one of said teeth, each tumbler comprising a pair of through- slots at opposed sides of the tumbler and at different levels thereon, each tumbler moving to a down-position upon depression of its associated pushbutton, a catch mechanism for retaining each tumbler in it's down- position upon depression of its associated pushbutton, and re- configuration means for selectively turning each tumbler to thereby present one of its through-slots to the carriage to define the combination of the lock such that any down-positioned tumbler associated with a correct selected combination pushbutton has said one of its slots aligned with its associated tooth, to thereby allow passage of that tooth therethrough, and wherein the -l2 carriage cannot move to allow sufficient rotation of the knob spindle to unlock the lock when of any one of said teeth strikes against a down-positioned non-combination configured tumbler.
2. The lock of Claim 1, wherein the carriage moves linearly along the chassis.

3. The lock of Claim 1, further comprising a plurality of pawl plates respectively interposed between each pushbutton and its associated tumbler and wherein the catch mechanism comprises a plurality of deflection springs that engage with the pawl plate.
3. The lock of Claim 2, wherein the carriage comprises a pair of parallel bars each having said teeth thereon - the teeth of one said bar facing the teeth of the other said bar and wherein said pushbuttons are providing in two parallel linear arrays.
4. The lock of Claim 3, wherein the deflection springs are mounted upon a common beam that is flanked by said bars.
5. The lock of Claim 3, wherein there is provided beneath each pushbutton a return spring.
6. The lock of Claim 1, wherein said re-configuration - l - means comprise respective screw heads keyed to each of said tumblers.
7. The lock of Claim 6, wherein each screw head has extending from it a spline that slides within a cavity of corresponding shape in each tumbler.
8. The lock of Claim 7, further comprising a respective compression spring surrounding each spline and biasing the screw head away from the tumbler.
9. The lock of Claim 1, wherein the knob spindle rotates a gear upon which there is mounted a pair of diametrically opposed bosses, one of which bears against the carriage depending upon the turning direction of the knob spindle.
10. the lock of Claim 3, further comprising a reset pushbutton that releases the pawl plates from the catch mechanism.