Child safety door latch

A closure retainment latch for cabinet doors and the like that provides a child resistant access protocol restricting opening to required user specific actions. A cabinet door handle selectively engages an interior magnet retainer latch allowing the door to open. Multiple handle engagement indicated operations are required to initiate handle drive activation and latch release in a rotational longitudinally engagement configurations of contoured interdependent engagement activation elements within the handle and latch specific cam engagement surfaces.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to safety devices for door latches to restrict access by children, specifically cabinets and cupboards.

2. Description of Prior Art

Prior art devices of this type have been directed towards a variety of profile locks and handles wherein children are unable to open the door by the usual handle rotation and latch movement associated therewith.

Such prior art devices can be seen, for example, in U.S. Pat. Nos. 5,360,243, 5,785,363 and U.S. Publications 2009/0030427 and 2009/0266121.

In U.S. Pat. No. 5,785,363 a child safety latch can be seen having a dual activation push button configuration wherein both the buttons must be pushed and held simultaneously to activate release of the engagement of an interior latch.

U.S. Pat. No. 5,360,243 claims a latching structure for use with cabinets having electromagnetic member to engage a latch member. A switch provides activation and release of the mechanical latch allowing the cabinet to be open.

U.S. Patent Publication 2009/0030427 A1 illustrates a control handle for a lock wherein a release button is slidably advanced and held to directly engage a shaft or door latch retraction allowing the door to open.

U.S. Patent Publication 2009/0266121 A1 shows a child proofing of a door latch that is adapted to a standard lock set that prevents the door knob from turning when engaged. A sliding plate holds a locking post in place with a notch preventing the door knob rotation unless disengaged by a control lever interengaged therewith.

SUMMARY OF THE INVENTION

A cupboard safety latch device that provides a handle and interior release mechanism which requires multiple user actions to activate and release for access. The handle having a secondary movable element that interconnects rotatable handle input with an interior magnetic release by interlocking drive elements. Two movements are user required both handle rotation and simultaneous button depression to achieve inner latch and interior release engagement.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1 and 2of the drawings, a safety door latch10of the invention can be seen having a handle assembly11, a cam rod release assembly12and a rod latch assembly13. The handle assembly11has two-part handle housing14and15respectively with a spring driven activator control button16which must be pushed in while the handle is being turned as will be described in greater detail hereinafter for operational engagement.

The control button16, best seen inFIGS. 1,6,7and8of the drawings has a main stepped annular body member17with a user end engagement portion17A and drive engagement portion17B. The drive portion17B has an annular gear surface18with a plurality of radially spaced teeth18A thereon. A rotational limitation engagement channel19extends partially within the control button16's main body member and an annular spring seat20in spaced relation thereto as best seen inFIG. 6of the drawings. A centered drive shaft receiving cavity21extends partially therewithin providing an engagement surface as will be described.

A drive lock fitting22, best seen inFIGS. 1,3,4and5of the drawings has a stepped annular body member23having a gear portion23A, a housing engagement portion24and a nut engagement portion25with a central bore at26extending therethrough. The gear portions23A has a plurality radially spaced teeth27for select engagement with the teeth18A on the button16. The housing engagement portion24has annular threads28extending therefrom for registration with corresponding threads28A on the inner surface IS of the housing part15as best seen inFIG. 1of the drawings.

As assembled, the drive lock fitting22is rotatably positioned on a drive shaft housing29having a central drive shaft30therewithin and extending therefrom as will be described in greater detail hereinafter.

The drive shaft housing29is cylindrical having a threaded exterior surface S with a compound smooth annular flange end31from which extends a rotational restriction about stopper bar32as best seen inFIGS. 1 and 11of the drawings. The drive lock fitting22, as noted, slips over the drive shaft housing29and abuts against the end flange31and is retained thereagainst by a drive lock nut33, best seen inFIGS. 1,9and10of the drawings. The drive shaft30has a corresponding retainment flange30A in retaining registration with the hereinbefore described flange end31of the drive shaft housing29. The drive shaft30has an area of reduced transverse dimension34extending from the flange end31of the drive shaft housing29registering within the shaft receiving cavity21of the button16. A spring35in the spring seat20extends about a portion of the drive shaft extension34and against the drive shaft30imparting a resilient action to the button16during use.

Referring now toFIG. 1of the drawings, the handle housing15can be seen having an interior annular stepped configuration corresponding to an exterior stepped surface of the button16and with the drive lock fitting22aligning same to afford selective button gear teeth18A and drive lock fitting22gear teeth27for selective engagement indicated by directional arrows A upon button16displacement within the handle housing portion15when in assembly as shown inFIG. 1of the drawings. The handle housing14rotatably supports the drive shaft housing29, drive shaft30therein and threaded engagement lock nut33, as assembled.

A handle spacer36and spacer lock retaining nut36A are threadably secured on the drive shaft housing29retaining the handle housing14for adjustable resistant rotation thereon.

The handle assembly11as hereinbefore described will provide for select operational rotation of the drive shaft30in the following user sequence.

The handle housings14and15can be freely rotated independently on the drive shaft assembly in non-engagement position illustrated inFIG. 1of the drawings, however, once the button16is depressed indicated by activation arrows A inwardly against the spring35, the respective gear teeth18A and27A engage effectively locking the button16to the rotatable drive lock fitting22thereby rotating the drive shaft30keyed therewithin. The rotational restriction stopper bar32extending from the drive shaft flange housing end32as described is correspondingly registered within the rotational limitation engagement channel19limiting the effective drive shaft30and therefore handle rotation when so engaged and turned.

Referring now to the cam rod release assembly12, best seen inFIGS. 1,2,13and14of the drawings, the cam rod release assembly12has a rectangular activation frame37, best seen inFIG. 1of the drawings with oppositely disposed top and bottom surfaces37A and37B respectively and spaced parallel front and back surfaces37C and37D as positioned in this illustration. The frame37has a central contoured opening therethrough at38and elongated lug39extending from the so defined front surface37C in co-planar relation to its bottom surface37B.

Pairs of surface engagement arcuate guide feet40A and40B extend in spaced parallel opposing relation to one another from the so-defined back surface37D of the rectangular activation frame37.

A cam fitting41can be seen in broken lines inFIG. 14of the drawings and best seen in solid lines inFIGS. 1 and 2of the drawings, has a cam engagement surface42with an extending annular drive shaft engagement sleeve43having an interior annular sidewall44with oppositely disposed parallel interior key engagement surfaces44A and44B therewithin. An outer annular spaced sidewall45defines therefore a spring channel46therebetween with a central opening at47extending through the cam fitting providing access for a fastener screw48to engage within an apertured end49of the drive shaft30.

The cam fitting41is registerable on the front surface37C of the frame37so as to rest in non-activated position on top of the elongated lug39with the drive shaft support sleeve43therefore extending into the contoured opening38as shown inFIG. 1of the drawings. The heretofore free end of the drive shaft49has a keyed surface extension of reduced transverse diameter49A which is engaged in the inner annular sidewall44keyed engagement surfaces44A and44B when assembled.

An apertured retaining disk50, see inFIGS. 1,2,16and17of the drawings is provided with a disk lock nut51is secured to the drive shaft housing29. The apertured retaining disk50has aligned spring engagement tabs52registerable against the outer sleeve45. A return spring53is secured at53A into the cam fitting41and extends between the respective inner and outer sleeves44and45being secured between the engagement tabs52of the retaining disk50so as to provide rotational spring return resistance to the cam fitting41when rotated by the drive shaft30during activation as hereinbefore described.

Referring back toFIG. 2of the drawings the rod latch assembly13can be seen having a latch activation rod54secured in and extending from the top surface37A of the hereinbefore described frame37. A rod guide bracket56is provided and mounted on the door D assuring latch activation rod54retention and alignment. The bracket56has a grub adjustment screw55therein that when engaged stops the rod54from moving so the magnet fitting58cannot draw the rod54into the locked position. A ferrous metal plate57secured to the free end of the activation rod54and is magnetically engaged by a magnet retaining fitting58mounted on the interior surface of a cabinet C on which the door D, in this example, is positioned.

It will be evident that the engagement rod54orientation when retained by the magnet fitting58will prevent the door D from freely opening until the handle assembly10of the invention is properly activated.

In operation, once the button16is pressed and the handle15is rotated simultaneously, the drive shaft30so engaged will correspondingly rotate the cam fitting41engaging and “sliding the frame37” on the inside of the door D thus pulling down in this illustrated orientation the activation rod54within the guide bracket56releasing same from the magnetic fitting58. At this point, the door D can be opened by pulling the handle assembly10as will be well understood by those skilled in the art.

As noted, the cam retaining spring53will return the cam fitting41once the handle15is released by the user, not shown. The rod54and frame37will remain in position and not return with the cam fitting41staying in the unlocked position until the magnetic fitting58can so engage and draw same to the lock as noted. It will be seen that the cam rod assembly12can be mounted in a horizontal orientation as shown inFIG. 15of the drawings so as wherein the cam fitting41is rotated with the engagement sleeve43shown in solid lines. The frame37will be slid horizontally as indicated by broken lines and the sleeve43will slidably engage into the enlarged area of the contoured opening38and retain the frame37in the “open” position by frictional gravity at59as the frame37drops slightly down vertical indicated by broken arrow V as well as horizontally as noted, by broken arrow H.

It will be evident from the above description that unless the button16is depressed, engaging the drive lock fitting22, that the handle15will just rotate without effective articulated latch release engagement.

It will thus be seen that a new and novel child safety door latch has been illustrated and described and it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the spirit of the invention.