US3606425A

US3606425A - Door latches

Info

Publication number: US3606425A
Authority: US
Inventors: Michael Joseph James
Original assignee: Micro and Precision Mouldings Cheltenham Ltd
Current assignee: Micro and Precision Mouldings Cheltenham Ltd
Priority date: 1968-05-27
Filing date: 1969-05-20
Publication date: 1971-09-20
Anticipated expiration: 1988-09-20
Also published as: DE1926851A1; GB1272764A; FR2009402A6

Abstract

A TUBULAR MORTICE LATCH HAS A ROTARY ACTUATING MEMBER FOR COUPLING TO A DOOR HANDLE AND AN INTERMEDIATE FOLLOWER MEMBER. BOTH MEMBERS PIVOT WITHIN A HOUSING ABOUT PARALLEL AXES, AND THE ACTUATING MEMBER ENGAGES AND TURNS THE FOLLOWER MEMBER WHICH IN TURN ENGAGES A BOLT TO WITHDRAW THE LATTER INTO THE HOUSING. THERE IS A PEG AND SLOT CONNECTION BETWEEN THE MEMBERS, AND THE SLOTTED MEMBER IS MOULDED FROM A RESILIENT MATERIAL WITH THE SLOT HAVING A REDUCED MOUTH SO THAT DURING ASSEMBLY IT SNAPS ON TO THE PEG.

Description

M. J, JAMES DOOR LATCHES Se t. 29,1971 1 I Sheets-Shoot 1 Filed May 20 1969 39 l all/7,954

% ATTORNEYS United States Patent 3,606,425 DOOR LATCHES Michael Joseph James, Charlton Kings, Cheltenham, England, assignor to Micro & Precision Mouldings (Cheltenham) Limited, Cheltenharn, England Filed May 20, 1969, Ser. No. 826,185 Claims priority, application Great Britain, May 27, 1968, 25,325/68 The portion of the term of the patent subsequent to Mar. 3, 1987, has been disclaimed Int. Cl. E05c 1/16 US. Cl. 292-173 5 Claims ABSTRACT OF THE DISCLOSURE A tubular mortice latch has a rotary actuating member for coupling to a door handle and an intermediate follower member. Both members pivot within a housing about parallel axes, and the actuating member engages and turns the follower member which in turn engages a bolt to withdraw the latter into the housing. There is a peg and slot connection between the members, and the slotted member is moulded from a resilient material with the slot having a reduced mouth so that during assembly it snaps on to the peg.

This invention relates to door latches of the mortice type having a slidable slam bolt mounted in a housing of generally tubular form, in use the latch being released by withdrawal of the bolt into the housing by turning door handles respectively mounted on opposite sides of the door and interconnected by an operating shaft. A door latch of this type is hereinafter referred to as a tubular mortice latch and the invention is an improvement in or modification of the invention disclosed in the specification of my co-pending application for Letters Patent No. 622,750 now Pat. No. 3,498,660.

In the specification of said application No. 622,750 I have disclosed a tubular mortice latch having a rotary actuating member for coupling to a door handle and an intermediate follower member which pivots Within the housing about an axis parallel to the rotary axis of the rotary actuating member. The follower member is engaged and turned by the actuating member to release the latch, the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing, and the arrangement is such that the angular movement of the follower member is greater than that of the actuating member. In that specification we have described a construction in which the actuating member has a peg and slot connection with the follower member, a peglike section of the actuating member parallel to the rotary axis of that member being able to turn Within a slot in the follower member during relative articulation of these members during latch operation.

According to the present invention the interconnection of the actuating and follower members is again achieved by means of a peg-like section on one engaging a slot in the other, but the slotted member is moulded from a resilient material and the slot has a reduced mouth so that during assembly it snaps on to the peg-like section and is thereby positively retained in the assembled latch. This avoids any possibility of the two members becoming detached during latch operation, and the peg-like section is desirably moulded on the actuating member.

The follower member preferably engages and pivots on a fixed abutment in the housing, this engagement defining an effective pivot axis offset vertically with respect to the bolt axis. The follower member is desirably double-acting so that either direction of handle moveice ment will effect latch release, and to this end the abutment may have a generally rectangular recess with radiused corners disposed symmetrically above and below the above axis and in either of which the follower memher, which is received within the recess, can engage and pivot dependent on the direction in which it is turned by the actuating member. Two such abutment recesses may be disposed one on either side of the housing and within which are received projecting side limbs of the follower member. The side limbs may respectively engage in these recesses to define the resting position of the bolt, the follower member being returned to the resting position by the bolt under the influence of the usual latch spring.

To accommodate the relative movement of the actuating and follower members within the housing when the said abutment recesses are employed, the peg and slot connection is preferably such that the peg can slide freely by an appropriate amount within the slot in a direction aligned with the longitudinal axis of the housing, considering the parts in said resting position. The peg may extend across substantially the full width of the follower member for engagement with aligned slots formed in inward projections of both side limbs of the follower memher, and the peg may be moulded to extend between two web-like projecting side arms on the actuating member, this construction providing relative lateral location for the two members. In a preferred construction each slotted projection of the follower member fits closely between one of said side arms of the actuating member and a central and similarly web-like arm thereon, so that the actuating member is of integral moulded construction with the connecting peg provided by two aligned peg-like sections each of which is of short length and rigidly supported between two projecting arms of the actuating member.

All the parts of the latch, with the exception of such spring or springs as are included, may advantageously be moulded from synthetic plastic material. Different materials may be used for the housing and the bolt to improve the frictional characteristics; for example, an advantageous construction results if the bolt is moulded from a material commonly known by the trademark Delrin, with the housing and remaining parts moulded in nylon. Delrin sliding on nylon provides extremely satisfactory friction characteristics.

The invention will now be further described with reference to the accompanying drawings which illustrate, by way of example, a tubular mortice latch in accordance with the invention. In the drawings:

FIG. 1 is an outer end view of the latch,

FIG. 2 is an axial cross-sectional view 11-11 in FIG. 1,

FIG. 3 is an axial cross-sectional view IIIIII in FIG. 2,

FIG. 4 is a lateral cross-sectional view IVIV in FIG. 2,

FIG. 5 is a lateral cross-sectional view V-V in FIG. 3, and

FIG. 6 is a scrap sectional view on the line VIVI in FIG. 3, showing the latch in the released condition.

A moulded nylon tubular housing 1 comprises a main portion 2 formed at the outer end with a fixing flange 3 and a guide bore 4 from which a slidably mounted slam bolt 5 projects. A closed-ended inner end portion 6 of the housing 1 fits closely into the inner end of the main portion 2 and is retained therein by opposed side projectons 7 which on assembly click into locating recesses 8 in the side wall of the main portion 2.

The portion 2 is of truncated circular cross-section, as shown clearly in FIG. 5, having parallel side walls 9 on the line on the line on the line on the line which are disposed vertically when fitted and are joined by arcuate upper and lower walls 10. Longitudinal strengthening webs 12 moulded externally on the side walls 9 lie within the overall pitch circle of the arcuate walls 10. Thus the housing 1 fits snugly into a plain cylindrical bore drilled from the edge of a door.

The housing portion 2 is moulded with intern-a1 side abutments 13 which are joined by a central domed spring abutment 14 so as to leave clearance with respect to the arcuate housing Walls 10, see particularly FIGS. 3 and 5. The bolt is moulded with a solid outer end portion 15 providing the usual bevelled and radiused nose of the bolt, and an adjoining short hollow box section 16 beyond which the bolt is split to provide upper and lower inwardly projecting limbs 17. The limbs 17 pass above and below, and project inwardly beyond, the abutments 13. A latch return spring 18 is held in compression between the spring abutment 14 and the solid end portion 15 of the bolt.

A moulded actuating member 19 has a square-section through aperture 20 for reception of an operating shaft (not shown) which passes through clearance holes 22 in the side walls 9 of the housing portion 2. The actuating member 19 is journalled in the housing 1, the journals being only in part moulded at 23 in the main portion, thus enabling the actuating member to be fitted from the inner end of the housing. The journals are completed by moulded arcuate recesses at 24 in the end portion 6.

A follower member 25, which in the operative sense interconnects the bolt 5 and the actuating member 19, has an outwardly projecting central web 26 positioned with side clearance between the housing abutments 13. The member also has projecting side limbs 27 (FIG. 3) which engage locating recesses 28 formed in the abutments 13. The follower web 26 has upper and lower projecting ears 29 (FIG. 2) which enter longitudinal slots 30 in the upper and lower bolt limbs 17 and engage the inner ends 32 of these slots, so that pivotal movement in either direction of the follower member 25 within the abutment recesses 28 will result in withdrawal of the bolt 5 into the housing 1 to release the latch. The released condition With the bolt 5 fully withdrawn is shown in FIG. 6.

Each abutment recess 28 is of rectangular profile with radiused corners disposed respectively above and below the bolt axis, and the follower side limbs 27 have end portions of rectangular cross-section and radiused upper and lower ends 34, as shown more particularly in FIG. 6, which fit closely within the recesses 28. Thus each radiused end 34 can engage and turn in the adjacent radiused corner of the corresponding recess 28, in which it is received in order to define a pivot axis for the follower member 25 which axis is parallel to, and may be either above or below, the rotational axis of the actuating member 19. The resting position of the bolt 5 is defined by engagement of the side faces on the rectangular projecting ends of the follower side limbs 27 with the bottom faces of the abutment recesses 28.

The follower side limbs 27 have inward projections 35 formed with elongated and inwardly open slots 36 aligned with the bolt axis in the resting position, as shown in FIG. 2. The actuating member 19 has three spaced outwardly projecting arms 37 joined across at the outer ends by an integral peg .38 of circular section. The peg 38 enters the slots 36 in the follower side limbs 27, which limbs fit between the outwardly projecting arms 37 of the actuating member 19, to provide a peg and slot connection between the actuating member and the follower member. Thus when the actuating member 19 is turned by means of the non-illustrated operating shaft it turns the follower member 25 which in turn acts to withdraw the bolt, as shown in FIG. 6.

Each slot 36 is moulded with a reduced mouth, provided by inturned end lips 41, so that during assembly it snaps on to the peg-like section 38 of the actuating member 19, thus utilising the natural resilience of the moulding material to retain the follower member 25 captive on the actuating member 19. There is thus no possibility of these parts becoming detached one from the other within the assembled latch, which is a marked advantage provided by the present invention.

As can be seen from FIG. 6, the arrangement is such that the angular movement of the follower member 25 is considerably greater than the angular movement of the actuating member 19. The actual angular movement ratio and the resultant bolt withdrawal for a given actuating member movement depends upon the dimensions of the various parts, as will be appreciated from the foregoing description. As in the present embodiment, it isv possible to achieve a very satisfactory bolt movement with a maximum actuating member movement of only 20 producing an angular movement of the follower member of about 50. This gives an idea of the advantageous movement ratios which can be achieved by means of the invention and without cutting away the housing wall to provide clearance for movement of the parts. In fact, a housing is obtained without any open side apertures other than side apertures for the handle shaft, which is extremely advantageous as open apertures allow the entry of wood shavings and sawdust which are almost inevitably present during fitting.

When the latch is to be used with unsprung door furniture auxiliary concentric return springs 43 acting on the actuating member '19 are fitted in the end housing portion 6. The springs 43 are compressed between the end wall of that portion and a plunger 44- axially slidable within the latter. The plunger 44 has a concave recess 45 which faces towards the actuating member 19 and is engaged by an inwardly projecting lobe 46 on that member. The recess 45 and lobe 46 are so shaped that movement of the actuating member 19 from the resting central position further compresses the auxiliary springs 43. Operative movement of the actuating member 19 is limited by engagement of one or other of the upper and lower side faces of the lobe 46 with the wall of the inner end housing portion 6 over a region where that portion is received within the main portion 2,, as shown in. FIG. 6.

The plunger 44 is guided at the outer end by a. bore 47 in the end portion 6, and at the inner end by engagement of a centrally projecting stub 48 which slides in a guide bore '49 in the end portion 6. If sprung door furniture is used, with handle return springs of adequate strength to return the handles and the actuating member 19, the springs 43 and the plunger 44 can be omitted. In this case the end portion 6 merely acts to seal the inner end of the housing 1 after the internal latch elements, other than the bolt, have been fitted through that end.

The bolt limbs .17 and the follower member 25 are formed so that they interengage, if the bolt 5 is pushed fully home into the housing 1, to retain the bolt in a completely retracted and non-projecting position. To this end the bolt limbs 17 are moulded with tooth-like projections such as 50, see FIGS. 2 and 3, within the slots 30, and the central follower web 26 is moulded with corresponding recesses such as 52 for engagement by the projections 50 if the bolt is pushed fully home with the follower (member 2 5 in the central resting position. Two projections 50 are respectively moulded on one side of one of the slots 30 and on the opposite side of the other slot 30, the recesses 52 in the follower member 25 being correspondingly positioned.

It is thus possible for a door manufacturer to supply doors with latches fitted and the bolts fully retracted so that they are not liable to accidental damage during transport and fitting of the doors. 'In addition a dust cap can be fitted in the open outer end of the housing, this providing a dust seal and further protecting the latch. With such a dust cap in position the door can also be painted without danger of the paint entering and gumming up the latch.

The inner end 39 of the bolt limbs 17 are considerably narrowed and extended at one side of the bolt axis, and the ends of these extensions have radially inwardly opposing bulbous formations 40. These extensions are received in upper and lower slots 42 in the actuating member 19 which extend into the shaft receiving aperture 20, so that the bulbous ends 40 (as shown in FIG. 3) enter the aperture 20 and engage the shaft resiliently when the latter is fitted. This can be utilised in a locking arrangement employing a shaft which, in known manner, is axially displaceable from one side of the door to a locking position in which it is inoperative to effect latch release. Such a shaft when in the locking position, in one known construction, allows the opposite side door handle to turn freely without turning the shaft, and the shaft may be formed with a side notch which in the locking position is engaged by the ends 40'. Such engagement then acts to retain the shaft in the locking position until freed by inward movement of the bolt 5 when the limb extensions 39 clear the notch in the shaft.

I claim:

1. A tubular mortice latch having a housing, a bolt slidable in the housing, a rotary actuating member for coupling to a door handle and an intermediate follower member which engages and pivots on two fixed abutments in the housing, such engagement defining an effective pivot axis oifset vertically with respect to the bolt axis and parallel to the rotary axis of the actuating member, one of said members being moulded from a resilient material with an elongated slot having a reduced mouth and the other of said members having a peg-like section which engages in the slot to provide a peg and slot connection which accommodates relative movement of the members and through which the follower member is engaged and turned to release the latch, the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing and the arrangement being such that the angular movement of the follower member is greater than that of the actuating member, said fixed abutments being disposed one on either side of the housing and respectively engaged by projecting side limbs of the follower member, and during assembly of the latch the reduced mouth of the slot providing a snap-together connection between two said members.

2. A latch according to claim 1, wherein the peg is formed on the actuating member and extends across substantially the full width thereof, and said slot is one of two aligned slots which are engaged by the peg and respectively formed in inward projections of said side limbs of the follower member.

3. A latch according to claim 2, wherein the peg extends between web-like projecting side arms on the actuating member, with the side limbs of the follower member disposed between the side arms to provide relative lateral location of the members.

4. A latch according to claim 3, wherein each slotted projection of the follower member fits closely between the adjacent one of said side arms of the actuating member and a central web-like arm of the actuating member, with the peg provided by two aligned peg-like sections each of which is rigidly supported between two of the projecting arms of the actuating member.

5. A tubular mortice latch comprising a housing, a bolt slidably mounted in the housing, a rotary actuating member arranged within the housing for coupling to a door handle, and an intermediate follower member also arranged within the housing so as to be engaged in turn by the actuating member to release the latch, one of said members being moulded from a resilient material with an elongated slot having a reduced mouth and the other of said members having a peg-like section which engages in the slot to provide a peg and slot connection which accommodates relative movement of the members with the reduced mouth of the slot providing a snap-together connection between the two members, the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing within which is disposed a fixed abutment having generally rectangular recesses with reduced corners disposed symmetrically above and below the bolt axis and in either of which the follower member, which is received within the recesses, can engage and pivot dependent on the direction in which it is turned by the actuating member so that in use either direction of handle movement will effect latch release with the follower member turning about a pivot axis which is parallel to the rotary axis of the actuating member and offset with respect to the longitudinal axis of the bolt, the angular movement of the follower member being greater than that of the actuating member.

References Cited UNITED STATES PATENTS 506,461 10/ 1893 Beckwith 292169.21 823,221 6/1906 Jorgenson 292-167X 2,160,301 5/1939 Baume 292-167 2,342,477 2/1944 Magnenat 16171UX 2,701,152 2/1955 Cutler 287--92 2,732,581 1/1956 Heck 16171X 3,498,660 3/1970 James 292173 ALBERT G. CRAIG, JR., Primary Examiner US. Cl. X.R.