US3016730A

US3016730A - Key locked door latch mechanism

Info

Publication number: US3016730A
Authority: US
Inventors: Sr George E Dey
Original assignee: G D M Co
Current assignee: G D M Co
Priority date: 1959-12-10
Filing date: 1959-12-10
Publication date: 1962-01-16
Anticipated expiration: 1979-01-16

Description

Jan 16, 1962 G. E. DEY, SR 3,016,7 0

KEY LOCKED DOOR LATCH MECHANISM Filed Dec. 10, 1959 2 Sheets-Sheet 1 IN V EN TOR.

1962 G. E. DEY, SR 3,016,730

KEY LOCKED DOOR LATCH MECHANISM Filed Dec. 10, 1959 2 Sheets-Sheet 2 if I 35 JNVENTOR.

llnited States Patent Ofiice fllfifldfl Patented Jan. 16, 1952 3,916,730 LSCKED D0468 LATCH MECHANISM Gent-go E. flay, Sn, Lowell, Mich, assignnr to GJ'lM. (Company, Lowell, Mich. Filed Dec. 10, 1959, Ser. No. 858,746 3 filaims. Cl. 70-150) This invention relates to improvements in key locked door latch mechanisms. The principal objects of this invcntion are:

First, to provide a door latch mechanism particularly adapted for trailers and mobile homes which can be selectively conditioned to permit locking from the outside and unlocking from the inside or fully locked condition against release from either side without a key.

Second, to provide a door latch mechanism which must be locked with a key and which automatically assumes unlocked condition upon retraction of the latch bolt so that the door can not he accidentally locked by closing the door.

Third, to provide a door latch mechanism which will retain the key therein and prevent withdrawal of the key in the lock actuating position of the lock cylinder requiring return of the cylinder to a neutral position which permits automatic unlocking of the latch from the inside.

Fourth, to provide a door latch structure having the foregoing factors which is relatively narrow or thin for installation in thin doors and which can be relatively inexpensively manufactured and assembled with a minimum number of parts.

Other objects and advantages of the invention will be apparent from a consideration of the following description and claims. The drawings, of which there are two sheets, illustrate a highly practical form of the latch structure.

FIG. 1 is a fragmentary view generally in plane from the inner side of the base and outer escutcheon plate of the latch assembly parts broken away and in cross section.

H6. 2 is a fragmentary cross sectional view taken along the plane of the broken line 2-2 in FIG. 1.

FIG. 3 is a fragmentary composite exploded view of the parts of the latch assembly taken along the plane of the line 33 in FIG. 1.

FIG. 4- is an enlarged fragmentary cross sectional view taken along the plane of the broken line 4-4 in FIG. 1.

FIG. 5 is a fragmentary enlarged cross sectional view taken along the plane of the line 5-5 in FIG. 1.

FIG. 6 is a fragmentary cross sectional view taken along the plane of the broken line 6--6 in FIG. 3 showing the lock bolt and lock cylinder in locked position.

FIG. 7 is a fragmentary view similar to FIG. 6 but showing the lock bolt and lock cylinder in unlocked position.

The primary body of the latch mechanism is formed on a generally rectangular base plate 1 which forms an outer escutcheon plate and which has an inwardly turned peripheral rim 2 adapted to be clamped against the outer surface of an outer door panel. Upstanding bosses 3 on the corners of the base plate define tapped holes 4 to receive screws not illustrated for clamping an inner escutcheon plate 5 to the inner side of the inner door panel and against the ends of the bosses with the inner and outer panels of the door clamped between the two escutcheon plates. It will be appreciated that the door will be provided with a suitable cavity near its swinging edge for receiving the internal portion of the latch mechanism.

Upstanding pillars 6 near the midsection of the base plate and a wall 7 near the outer or swinging edge of the base plate from a slidable support and way for a reciprocable latch bolt 8 having a keeper engaging nose 9 projecting beyond the edge of the base plate. Overhanging cars 10 on the end bosses 3 retain the latch bolt on its ways. The outer or projecting end or nose 9 is cammed for engagement with a keeper as is common and the central and inner portions of the latch bolt defines a longitudinal slot 11 extending to adjacent the inner end of the latch bolt. Transversely projecting pawl engaging cars 12 are formed on the inner end of the latch bolt and project inwardly and outwardly of the door on opposite sides and at the opposite edges of the latch bolt. A transversely projecting arm 13 on one side of the latch bolt acts as an abutment for the coiled latch spring 14 having its other end abutted against the fixed wall 15 to constantly bias the latch bolt to the projected position illustrated. A guide pin 16 positioned within the spring prevents its collapse and slides through a hole in the arm 13 as the latch bolt is retracted in opening or closing the door.

Positioned within the inner end of the slot Ill in the advanced latching position of the latch bolt is an outer latch pawl 17 having a hub 18 projecting inwardly into the slot 11 to guide the inner end of the latch bolt and having an outwardly extending stem 19 projecting through a hole Ztl provided therefor in the base plate. An outer door knob 21 is secured to the stem 19 and has an hub 22 journaled in the hole 20 for locating and guiding the rotation of the outer latch pawl 17. The outer latch pawl 17 has transversely projecting arms 23 which are opposed to and engageable with the facing lower sides of the pawl engaging ears 12 on the latch bolt. Thus rotation of the outer handle 21 in either direction will cause one or the other of the arms 23 to cammingly engage the latch bolt and retract the bolt and its nose 9 for releasing the latch. The outer latch pawl 17 has a longitudinally extending lock arm 2 5 that projects toward the nose 9 in the neutral position of the latch bolt and which is supported for rotation in a plane by the circular wall 25 on the inner side of the base plate. The locking arm 24 has transversely spaced lugs 26 on its inner face which define a locking slot 27 between themselves faced toward the inner side of the outer latch pawl and extending longitudinally of the latch bolt in the neutral position of the outer latch pawl.

Supported against the inner side or" the latch bolt 8 and coaxial with the outer latch pawl 17 is an inner latch pawl 28 having an outer hub 29 guidingly received in the end of the slot 11 in the latch bolt. An inner stem 39 projects inwardly from the inner latch pawl for connection to the inner door handle 31. Projecting transversely from opposite sides of the inner latch pawl are oppositely extending arms 32 opposed to and engageable with the inner side portions of the pawl engaging cars 12 on the latch bolt. It will thus be seen that rotation of the handle 31 in either direction from a neutral position will function to retract the: latch bolt and its nose 9.

The outer or underside of the latch bolt 8 as shown in the drawings is shouldered as at 33 to form a retaining slide and guide way for a generally rectangular lock bolt 34 which is thus slidably retained in the slot 11 and against the columns 6 for sliding motion longitudinally of the base plate and relative to the latch bolt 8. At its inner or left end as shown in FIGS. 1 and 2, the lock bolt 34 carries a depending or outwardly projecting locking stud 35 which is movable longitudinally into and out of the locking slot 27 on the outer latch pawl upon longitudinal motion of the lock bolt. Motion of the lock bolt 34 is limited by a screw 36 passed through the slot 37 in the lock bolt and received in the column 6 on the base plate outwardly from the lock bolt. In order to restrain movement of the lock bolt 34, its undersurface is provided with spaced circular recesses 58 cooperative with a spring pressed ball 39 received in the bore 40 in the column 6. A manually operable pin 41 projects inwardly from the lock bolt for shifting the lock bolt from the inner side of the latc'hmechan'ism.

A pair of saddles 412 projecting inwardly from the base plate ll alongside of the lock bolt and latch .bolt rockably support a short interlock shaft 43 having an upstanding arm 44 rockably or tiltably received in a recess 45 provided therefor on the outer or lower side of the lock bolt34. A second arm 4-6 on the interlock shaft projects upwardly into the path of a lug 4-7 on the side of the latch bolt so that if the latch bolt is retracted as by closing the door or actuating the inner door handle 31, the interlock shaft 43 and arm 44 automatically move the lock bolt 34 to the left as shown in FIGS. 1 and 2 and move the locking stud 35 out of the locking slot 27. It is thus impossible to lock oneself out of the building or spaceto which the latch structure is applied and it is also impossible except as will be described presently for someone to lock the latch mechanism from the outside and prevent someone accidentally locked inside from unlocking and opening the latch. This is of particular importance in trailer and mobile homes Where the door may be the only possible means for exit in the event of an emergency.

The lock bolt 34 is movable to locked position from the outside of the door and latch structure by means of a key operated lock cylinder 4-3 rotatably received in a boss 49 provided therefor on the base plate 1. The boss defines a lock receiving bore d with radially extending grooves El and 52 formed in the side thereof. The groove 51 is 45 above the horizontal and the groove 52 is 35 below the horizontal. The lock cylinder is retained in the bore 54 as is common by means of a snap ring 53 (see FIG. 3) adapted to be snapped into agroove .54 in the lock cylinder at the inner end of the bore. The lcck cylinder is provided with a key retaining pin-55 and locking pins 56 which are projectable into the

grooves

51 and 52. As is common in lock cylinders of this type the key retaining pin 55 functions to retain the key 58 in the lock cylinder unless the pin is projected from the side of the cylinder. The locking pins 56 conventionally prevent rotation of the locking cylinder by engagement in the groove 51 until retracted into the lock cylinder by the familiar action of inserting the key.

A pin-like projection 57 on the inner end of the lock cylinder projects into a recess provided therefor in the underside of the lock bolt 34. The recess is defined by spaced actuating

surfaces

59 and 6% connected by a stop surface 61. The action of the lock cylinder in locking and unlocking the latch is best shown in FIGS. 3, 6 and 7. The neutral position of the projection is at 57A in which position the pins 55' and 56 will project into slot 51 releasing the key and locking the lock cylinder against rotation. In this neutral position the actuating surfaces .59 and 69 can be. moved to either locked or unlocked positions of the lock bolt 34- as by actuation of the lock setting pin 46 from inside the door or by slamming the door with resultant retraction of the latch bolt 8 and actuation of the interlock shaft 43.

To lock the latch from the outside the key is inserted and turned clockwise 90 to swing the projection 57 to position 573 as shown in FIG. 6. This advances the lock bolt to the right, moving the stud 35 into locking position in the slot 27 in the outer latch pawl. The pins 55 and 56, held retracted by the key, rotate past the groove 52 so the key and lock cylinder must be reversely rotated counterclockwise. Without further structure the pins 55 and 56 could project into the groove 52 permitting the key to be withdrawn with the lock cylinder and pro ection 57 in locked position after a short reverse rotation. However, a screw 62 passed through the wall of the boss 49 is screwed in into the path of the key retaining pin .54 preventing removal of the key. The

key naturally holds the lock pins 56 retracted so the operator must return the key and lock cylinder to neutral position to remove the key. The latch is then locked due to the shifted position of the lock bolt but free to be unlocked from the inside as described.

When it is desired to more positively lock the latch, as during movement of the trailer, the screw 62 can be backed out as shown in FIG. 5 at which time the key can be withdrawn with the lock cylinder 4-8 and projection 57 in locked position only slightly retracted from position 573. This positively prevents retraction of the lock bolt which in turn prevents retraction of the latch bolt and the only way to open the latch is with the key.

In unlocking the latch from the outside, with the key as is necessary, the key is inserted in the neutral position of the lock and the cylinder turned counter-clockwise to the position shown in FIG. 7. In so doing the projection 57 acts on the side surface 59 to retract or unlock the lock bolt 34. Note in FIG. 7 that the projection 57 is stopped by the back surface 61 of the recess. The purpose of this is to prevent counterclockwise rota tion of the lock cylinder to a point where the key retaining pin 55 could extend into the notch 63 which is 35 above the horizontal and permit release of the key from the cylinder. Thus the key and cylinder must be returned to neutral position after an unlocking as well as a locking motion.

What is claimed as new is:

1. in a door latch structure having a base with a spring pressed latch bolt reciprocatingly mounted thereon and operatively associated with'separate inner and outer door .knob operated pawls, a lock bolt reciprocably mounted in a slot provided therefor in said latch bolt and having a locking stud lockingly engageable with said outer knob operated pawl to the exclusion of said inner operated pawl in the neutral position of the knob pawl and the extended locked position of the locking stud, means engageable between said latch bolt and said lock bolt to disengage said locking stud upon retraction of said latch bolt, a manually operable pin projecting inwardly from said lock bolt for operation from inside the door independently of said latch bolt, means secured to said base limiting movement of said lock bolt between locked and un ocked positions of said stud, a key operated lock cylinder mounted in said base and operative from the outside thereof, an eccentric projection on the inner end of said cylinder extending into the slot in said latch bolt, actuating surfaces spaced longitudinally on the outer side of said lock bolt and engageable by said projection in oppositely rotated positions of said cylinder and projection to lock .and unlock said lock bolt, a longitudinal surface on said lock bolt connecting said actuating surfaces and engageable with said projection to prevent rotation of said cylinder beyond said oppositely rotated positions, cylinder locking and key retaining pins projectable from said cylinder, and pin receiving grooves formed in said base around said cylinder to receive said pins in the neutral position and the lock bolt locking position of said cylinder, said base having a screw accessible from the edge of said base and selectively advanceable into one of said grooves in the path of said key retaining pin to hold the pin retracted and permit removal of the key in the bolt locked position of the cylinder.

2. .In a door latch structure having a base with a spring pressed latch bolt reciprocatingly mounted thereon and operatively associated with separate inner and outer door knob operated pawls, a lock bolt reciprocably mounted in a slot provided therefor in said latch bolt and having a locking stud lockingly engageable with said outer knob operated pawl to the exclusion of said inner operated pawl in the neutral position of the knob pawl and the extended locked position of the locking stud, means engageable between said latch bolt and said lock bolt to disengage said locking stud upon retraction of said latch projection to lock and unlock said lock bolt, cylinder locking and key retaining pins projectable from said cylinder, and pin receiving grooves formed in said base around said cylinder to receive said pins in the neutral position and the lock bolt locking position of said cylinder.

3. In a door latch structure having a base with a spring pressed latch bolt reciprocatingly mounted thereon and operatively associated with separate inner and outer door knob operated pawls, a lock bolt reciprocably mounted in a slot provided therefor in said latch bolt and having a longitudinally disengageable locking engagement with said outer knob operated pawl to the exclusion of said inner operated pawl in the neutral position of the knob pawl and the extended locked position of the locking bolt, means engageable between said latch bolt and said lock bolt to disengage said locking engagement upon retraction of said latch bolt, a manually operable pin projecting inwardly from said lock bolt for operation from inside the door independently of said latch bolt, a key operated lock cylinder mounted in said base and operative from the outside thereof, an eccentric projection on the inner end of said cylinder, actuating surfaces spaced longitudinally on the outer side of said lock bolt and engage able by said projection in oppositely rotated positions of said cylinder and projection to lock and unlock said lock bolt, cylinder locking and key retaining pins projectable from said cylinder, and pin receiving grooves formed in said base around said cylinder to receive said pins in the neutral position and the lock bolt locking position of said cylinder.

References Cited in the tile of this patent UNITED STATES PATENTS 2,164,290 Hurd June 27, 1939 2,370,645 Fall: Mar. 6, 1945 2,469,018 Swanson May 3, 1949 FOREIGN PATENTS 183,286 Great Britain July 27, 1922 34 5,10 8 Germany Dec. 6, 1921