GB2258266A - Automatically releasing door handle snib - Google Patents

Abstract

A snib mechanism for a door latch and handle assembly is arranged to be automatically released on rotation of the internal door handle. The external handle 5 is mounted on a shaft 8 which carries at its inner end a rotatable member 14 having a peripheral notch 44. Member 14 also carries a pin 82 whereby rotation is transmitted to inner handle and vice versa via a slot 80 on member 12 attached to the shaft of the inner handle 6. The snibbing member 42 is pivotable by thumb piece 47 to engage the notch 44 thus preventing movement of the external handle. However, on rotation of inner handle, member 12 rotates through the lost motion of slot 80 (ie without driving the external handle), and disengages the snib member, lifting it out of the notch 44 by pin 86 on the snib riding up cam surface 84 of member 12. Further rotation of the inner handle then drives the main shaft 8 and disengages the door latch. Pivoted lever 62 may be provided to allow for emergency release of the snib member by insertion of a screwdriver and the like in opening 70 provided in the outer cover 23. <IMAGE>

Description

"RELEASABLE SNIB MECHANISM FOR DOOR HANDLES" This invention is concerned generally with door furniture and more particularly relates to privacy units which provide for a door handle to be snibbed from one side and yet be readily releasable in an emergency to permit access through the doorway from the other side. Such units are commonly used, for example, on bathroom and toilet doors.

The applicant's International Patent Application PCT/AU90/00240 filed 1 June 1990 describes a snib mechanism for a door latch assembly. The snib mechanism described enables an occupant of a bathroom or toilet to lock the door against entry by moving a snib member. The disadvantage of this mechanism is that the occupant must disengage the snib mechanism by returning the snib member to its original position before the door can be opened by the occupant. The present invention seeks to overcome this problem.

According to a first aspect of the present invention there is provided a releasable snib mechanism for a door latch assembly, comprising: a body; a rotary member disposed in said body and adapted to be engaged by and rotated with a door latch shaft; a snib member mounted on the body for movement between a snibbing position in which said rotary member is snibbed against rotation and a freeing position in which said rotary member is free to rotate with said door latch shaft; and a snib release member mounted on a shaft means, said snib release member arranged upon rotation of said shaft means to move said snib member from said snibbing position to said freeing position and upon continued rotation of said shaft means to provide rotation to said door latch shaft.

In a second aspect of the present invention there is provided a releasable snib mechanism for a door latch assembly, comprising: a body; a rotary member disposed in said body and adapted to be engaged by and rotated with a door latch shaft; a snib member mounted on the body for movement between a snibbing position in which said rotary member is snibbed against rotation and a freeing position in which said rotary member is free to rotate with said door latch shaft; a release lever adapted to be supported by said body for rocking movement effective to move said snib member from said snibbing position to said freeing position, which release lever, when supported by said body on a door, extends through the door for engagement from the other side of the door to cause said rocking movement, and wherein said rocking movement is in a plane transverse to the door; and a snib release member mounted on a shaft means, said snib release member arranged upon rotation of said shaft means to move said snib member from said snibbing position to said freeing position and upon continued rotation of said shaft means to provide rotation to said door latch shaft.

Preferably the door latch shaft and the shaft means are co-axial and are engaged by complementary slot and pin means on the snib release member and the rotary member. The complementary slot and pin means enables the shaft means to partially rotate before the door latch shaft and shaft means are locked together and thereafter rotate in unison.

In a preferred arrangement the snib release member has a cam surface arranged to contact a pin on the snib member. Upon rotation of the snib release member the contact between the cam surface and the pin provides pivotal movement to the snib member to thereby move the snib member from the snibbing position to the freeing position.

Preferably, one end of the release lever is proximate to an adjacent portion of the snib member whereby the rocking movement of the lever causes said end thereof to engage said adjacent portion of the snib member and directly move it to the freeing position. The snib member is preferably rotatably mounted on said body and includes an integral dog engageable, in the snibbing position, with a notch on the snib member, and an outwardly projecting actuation arm exposed for manual setting of the snib member. The axis of rotation of the snib member is preferably parallel to the axis of rotation of the latch shaft.

The mechanism preferably further provides means projecting from said body to provide a fulcrum for the release lever, which fulcrum, when the mechanism is mounted to a door, lies within the door. The fulcrum is conveniently an upstanding ledge and the lever includes a concave seat for the ledge whereby the rocking movement is in a vertical plane. The release lever is preferably a shaped plate member.

The mechanism may further include a cover plate for the outside of the door which defines a cavity to receive the outer end of the release lever, an opening being provided into the cavity by the cover plate to receive a tool for effecting the rocking movement of the release lever.

Advantageously, the snib mechanism further includes an indexing spring member which biases the snib member towards the snibbing and freeing positions as it approaches the respective positions.

Preferably the door latch shaft is arranged to be attached to a handle on the outside of the door and the shaft means is arranged to be attached to a handle on the inside of the door.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a releasable snib mechanism according to an embodiment of the invention; Figure 2 is a cross-section on the lines A-A in Figure 1; and Figure 3 is a cross-section along line B-B in Figure 1.

Figure 1 illustrates a typical door latch assembly including a pair of handles 5, 6. Handle 5 which extends from the outside of the door is mounted on a latch shaft 8 which passes through a coupling mechanism. Handle 6 which extends from the inside of the door is mounted on a shaft 10. The latch shaft 8 and shaft 10 are co-axial and are connected by complementary slot and pin means 11 on the snib release member 12 and the rotary member 14. This connection is described in more detail below. The necessary door cavity 16 is covered at each side of the door by respective cover plates 18, 20 and by escutcheon plates 22, 23. At least escutcheon plate 22 is threadably engaged with cover plate 18.

For the purposes of a preferred embodiment of the present invention, the latch assembly is provided with a releasable snib mechanism which includes a rotary member 14 on latch shaft 8, a pivotally mounted snib member 24, a rockable release lever 26 extending through cavity 16 between the sides of the door, and a snib release member 12 mounted on shaft 10.

Rotary member 14 and snib member 24 are mounted in a thin cavity defined between cover plate 18 and a peripherally flanged housing 28 disposed behind the cover plate. Housing 28 has the usual rib segments 29 on its rear face for engaging the sides of cavity 16 and a pair of apertures 30 to receive screws by which housing 28 and cover plate 20 may be fastened to threaded spacer tubes (not shown) extending across cavity 16. On its front face, housing 28 has integral threaded bosses 34 to receive further screws by which cover plate 18 is fastened to housing 28.

Rotary member 14 has a central cavity 36 with side flats so that the rotary member irrotationally engages latch shaft 8 and is thereby rotatable with the shaft.

Snib member 24 is rotatably supported on a pin 40 formed integrally on housing 28 for rotational movement between a snibbing position (shown in Figure 2 in solid outline) in which a dog 42 on snib member 24 firmly engages a notch 44 on rotary member 14 and thereby snibs the rotary member 14 against rotation, and a freeing position (shown in dashed lines in Figure 2) in which the dog is disengaged from the notch and the rotary member 14 is free to rotate with the latch shaft 8. An integral actuation arm 46 on snib member 24 projects through a slot 48 in the flange of housing 28 and has an enlarged serrated head 47 which is manually engageable to set the snib member.

Setting of the snib member 24 is facilitated by a "U"-shaped indexing spring 50 which has out-turned legs 52, 53. These legs tightly seat in respective "V"-shaped notches 54, 55 on housing 28 and in the end of snib member 24 remote from dog 42. The arrangement is such that the minimum separation of the legs of spring 50 occurs when the snib member 24 is midway between the snibbing and freeing positions, whereby the spring biases the snib member towards whichever of the positions it is approaching.

Release lever 26 is a shaped metal plate. About midway between its ends, lever 26 is shaped to form a concave seat 62 which receives, and by which the lever thereby rests on, an upstanding ledge 64 on a bracket 60 projecting into cavity 16 from housing 28. Ledge 64 thereby provides a fulcrum about which the lever is rockable in a vertical plane transverse to the door.

The weight distribution of the lever is such that at its end 65 adjacent housing 28, the lever tends to lie against or just above the floor of bracket 60. This end 65 lies below a pin 66 projecting integrally from snib member 24 through an opening 68 in housing 28, the arrangement being such that, when the snib member 24 is in its snibbing position, pin 66 lies just above the end 65 of lever 26. If the other end 67 of lever 26 is now pressed downwardly to rock the lever on the fulcrum provided by ledge 64, end 65 is lifted against pin 66 and moves snib member 24 from its snibbing position to its freeing position, aided towards the end of the movement by the indexing spring 50.

To make the rocking movement of lever 26 possible from the outside of the door, end 67 of the lever projects across cavity 16 and into a cavity 70 defined at the top of cover plate 20. This cavity 70 is open at the top at 72 so that any suitable tool, such as the tip of any screwdriver, a hairpin, a needle or an unwound paper clip can be inserted through opening 72 and engaged with lever 26 to effect the aforementioned rocking movement to move snib member 24 to its freeing position. No particular dimension, shape or tip configuration is needed for the releasing tool so long as it can be dropped into cavity 70 and pressed against lever 67.

Bracket 60 is an integral piece of generally square-"U" cross-section with vertical slots 74 (Figure 3) on its outside face for engaging complementary outstanding ribs 75 on an integral U-section land 76 outstanding from the outside face of housing 28.

Snib release member 12 is keyed onto shaft 10. Complementary slot and pin means 11 on the snib release member 12 and the rotary member 14 are arranged to enable connection between the latch shaft 8 and shaft 10. The complementary slot and pin means 11 are configured to allow the shaft 10 to partially rotate before the latch shaft 8 and the shaft 10 are locked together and thereafter rotate in unison. The complementary slot and pin means 11 takes the form of an elongated arcuate slot 80 on the snib release member 12 and a pin 82 on the rotary member 14 (Figure 2). Snib release member 12 has a cam surface 84 which contacts with a cam member 86, in the form of a pin projecting outwardly from the snib member 24. The cam surface 84 is formed as a groove 84a.

When the snib member 24 is in the snibbing position the cam member 86 is positioned centrally in the groove 84a. When handle 6 is rotated snib release member 12 also rotates causing the cam surface 84 to contact the cam member 86. The contact between the cam surface 84 and cam member 86 causes the snib member 24 to pivot about pin 40 lifting the dog 42 out of the notch 44. The snib member 24 then moves to the freeing position.

Upon continued rotation of the handle 6 the snib release member 12 rotates until pin 82 contacts against the end wall of the elongated slot 80. At this point the latch shaft 8 and shaft 10 are connected and rotate in unison to operate the door latch (not shown). Slot 80 is elongated to provide a slack or delay in the connection between the latch shaft 8 and shaft 10 when handle 6 is rotated. This slack is necessary to enable release of the dog 42 from the notch 44.

The snib release member 12 and associated mechanism allows the release of the snib member 24 by simply turning handle 6. Thus it is not necessary to unlatch the. snib release member 12 manually by moving actuation arm 46.

It will be appreciated that the illustrated mechanism provides all the desirable features of a privacy door latch unit in a configuration which is relatively economic to manufacture, has minimal moving parts and can be relied upon to operate even after long periods of dormancy. The occupant of a bathroom or toilet with a door fitted with the mechanism can easily lock the door against ordinary entry by moving the serrated head 47 to engage the snib member 24 with the rotary member 22 and thereby lock the latch shaft 12.

The occupant can still then leave the room simply by turning handle 6. If an emergency situation arises and a person outside the door must gain access to the room, that person can use any available suitable tool to engage and depress the outer end of lever 26, to thereby release the snib member from snibbing engagement with the rotary member 22. Both snib setting and snib releasing actions, whether from inside or outside, are facilitated by the indexing spring 50.

Claims (19)

THE CLAIMS

1. A releasable snib mechanism for a door latch assembly, comprising: a body; a rotary member disposed in said body and adapted to be engaged by and rotated with a door latch shaft; a snib member mounted on the body for movement between a snibbing position in which said rotary member is snibbed against rotation and a freeing position in which said rotary member is free to rotate with said door latch shaft; and a snib release member mounted on a shaft means, said snib release member arranged upon rotation of said shaft means to move said snib member from said snibbing position to said freeing position and upon continued rotation of said shaft means to provide rotation to said door latch shaft.

2. A releasable snib mechanism according to claim 1 wherein the door latch shaft and the shaft means are co-axial and are engaged by complementary slot and pin means on the snib release member and the rotary member.

3. A releasable snib mechanism according to claim 1 or claim 2 wherein the snib release member has a cam surface arranged to contact a surface on the snib member.

4. A releasable snib mechanism according to claim 3 wherein the surface forms part of a pin mounted to or integral with the snib member.

5. A releasable snib mechanism according to claim 4 wherein the pin is arranged such that upon rotation of the snib release member contact between the cam surface and the pin provides pivotal movement to the snib member to thereby move the snib member from the snibbing position to the freeing position.

6. A releasable snib mechanism according to any one of the preceding claims further comprising an indexing spring member which biases the snib member towards the snibbing and freeing positions as it approaches the respective positions.

7. A releasable snib mechanism according to any one of the preceding claims further comprising a release lever adapted to be supported by said body for rocking movement effective to move said snib member from said snibbing position to said freeing position, which release lever, when supported by said body on a door, extends through the door for engagement from the other side of the door to cause said rocking movement, and wherein said rocking movement is in a plane transverse to the door.

8. A releasable snib mechanism according to claim 7 wherein one end of the release lever is proximate to an adjacent portion of the snib member whereby the rocking movement of the lever causes said end thereof to engage said adjacent portion of the snib member and directly move it to the freeing position.

9. A releasable snib mechanism according to claim 8 wherein the snib member is rotatably mounted on said body and includes an integral dog engageable, in the snibbing position, with a notch on the snib member, and an outwardly projecting actuation arm exposed for manual setting of the snib member.

10. A releasable snib mechanism according to any one of claims 7 to 9 further comprising means projecting from said body to provide a fulcrum for the release lever, which fulcrum, when the mechanism is mounted to a door, lies within the door.

11. A releasable snib mechanism according to claim 10 wherein the fulcrum is conveniently an upstanding ledge and the lever includes a concave seat for the ledge whereby the rocking movement is in a vertical plane.

12. A releasable snib mechanism according to any one of claims 7 to 11 wherein the release lever is a shaped plate member.

13. A releasable snib mechanism according to any one of the preceding claims wherein the axis of rotation of the snib member is substantially parallel to the axis of rotation of the latch shaft.

14. A releasable snib mechanism according to any one of the preceding claims further comprising a cover plate for the outside of the door which defines a cavity to receive the outer end of the release lever, an opening being provided into the cavity by the cover plate to receive a tool for effecting the rocking movement of the release lever.

15. A releasable snib mechanism according to any one of the preceding claims wherein the door latch shaft is arranged to be attached to a handle on the outside of the door and the shaft means is arranged to be attached to a handle on the inside of the door.

16. A releasable snib mechanism according to any one of the preceding claims wherein the rotary member has a central cavity with side flats so that the rotary member can be irrotationally engaged with the door latch shaft and is thereby rotatable with the shaft.

17. A releasable snib mechanism according to any one of the preceding claims wherein the snib member is biased by a spring member towards either the snibbing or freeing position depending on the position of the snib member.

18. A releasable snib mechanism substantially as hereinbefore described with reference to the accompanying drawings.

19. The features disclosed herein or any combination thereof.