US2587867A - Latch mechanism - Google Patents

Description

March 4, 1952 H. R. LINDERFELT 2,587,367

LATCH MECHANISM Filed Aug. 6, 1948 2 SHEETS-SHEET 1 JIIA'IIIIIIIIA i IIIIIIH II/l/I/I/II/I/l" Hal Raymond Linderfelf i 2 INVENTOR.

BY K

A 7' TORNE Y March 4, 1952 H. R. LINDERFELT LATCH MECHANISM 2 SHEETS--SHEET 2 Filed Aug. 6, 1948 Hul Raymond Lihderfelt ATTORNEY Patented Mar. 4, 1.952

' LATCH: MECHANISM Hal Raymond Linderfelt, West Los, Angeles, Calif., assig nor to Douglas. Aircraft Company, Inc., a corporation of California ApplicationAugust: 6, 1948,. Serial No. 42,776

3 Claims. (Cl. 292--335) The present invention relates to; closures and doors a d more. articularly to mnr vedm nisms for the automatic locking against inadc vertent operation oi doo r latching mechanism in the open position of the door,

The present invention relates to improvements in mechanism-s for locking a door or closure latching handle in the unlatched position, of the latch bolt or bolts to thereby hold the same in their retracted positions within the door to prevent accidental or inadvertent movement of the handle to the position in which the latch bolt might beextended and damage or mar the door jamb in the event of the closure of the door.

The present improvements are particularly adapted to aircraft doors of the flush or streamlined type in which a close and accurate fit of the door within its opening is desirable for aerodynamic reasons and particularly so in the event of scaled doors in pressurized or supercharged aircraft.

It is accordingly a principal object of th present invention to provide improved door latching and locking mechanisms. A further object resides in the provision of automatic means for preventing the extension of the latch bolts ofa closure or door at such times when the door is in other than its closed position. Another object resides in the provision of relatively simple, yet positive-acting and foolproof mechanism for blocking the latching movement of the bolt of a door when the same is not in the closed position. Further objects of the present invention reside in improvements in the general arrangement and relationship of the interlocking mechanism with respect to the latching mechanism of a door, as well as in detailed improvements of the respective elements.

Other objects andadvantages of the present invention will occur to those skilled in the art after reading the following description taken in conjunction with the accompanying drawings, forming a part hereof,in which:

Fig. l is an elevational view of a door to which the improved mechanism has been applied;

Fig. 2 is a detail view of the improved mechanism in the unlatched open position ofthe door;

Fig. 3 is a cross-sectional elevational view of the mechanism of Fig. 2 as taken along the.lines 3- 3 thereof;

Fig. 4 is a sectional plan view of the mechanism in both the open and closed positions of the door; and

Fig. 5 is a similar vie-w of a portion of the mechanism of Fig. 2, in thelatched closed .position of the door.

Referring now to Fig. 1, the numeral 7 represents a wall or enclosure which may be the interior surface oi the wall of an aircraft. This wall has an opening therein, as defined by the jamb 28, within which there is disposed a closure or door 8, which. door is preferably mounted upon the hinges 9 for movements between its opened and closed positions. The numeral It in Fig. 1 indicates the base plate or portion of. a housing I8 for the improved mechanism of the present invention, which housing and mechanism is shown in greater detail in the remaining figures.

Referring more particularly to Figs. 2 and 3, it will be noted that the base plate 10 is rabbetted or-recessed on its outer face toreceive the outer sheet or skin of the door to which the flange of the base portion [8 is attached through its holes ltd, and the holes 8a of the door sheet, as by the rivets or other fastening. means H. A major portion of the improved mechanism is housed within the housing or cover l8 which is suitably bored, together with the base plate In and the cover sheets of the door, to rotatably support .a handle shaft 12, having an internal handle I3 and an external handle I3a fixedto the inner and outer terminals thereof, respectively. A latch stop element MisfiXedly attached to the shaft [2 in such manner that it-rotates with the shaft as the handles l3 and I3a are manually rotated. This element 14 has an extended por tion bifurcated at Mb to which the roller I5 is pivoted at Ma.

The handle assembly l2-l3|4 etc. is resiliently heldin either one of two alternate positions by means of a snap-action spring toggle rod [6 which is pivotally attached .to the latch stop element M. by means of the pivot pin H. The toggle rod I6 is guided for reciprocationat its outer terminal through the apertured guide or pillow block 30, which in turn is pivotally mounted upon the shaft 3l fo r partial rotation or rocking within suitably, b ored portions formed in the base plate I and the housing cover I81. Inasmuch as the pivot 11 is e'ccentrically, disposed with respect ,tothe. axis of the handle shaft, l2 and the spring .29, which is sleeved upon the rod [6, is continually under. compression, the pivot I1 is at all times urged away from the pivot shaft 3|. Accordingly, as the handle shaft I'Zis rotated past the dead centerline, joining the axes of shafts I 2 and 3f. the spring, 29 in extending the distance between these pivots, causes. the latch stop element M, to which itis pivotally at tached, to be quickly rotated to either of its alternate limit positions. By referring to Fig. 2, it will be seen that a stop portion l 8a is integrally formed within the housing coverl8 andin this figure the latch stop element [4 jhas'been rotated about shaft I2 as far as it can go in the counterclockwise dire'ction. This position of the. toggle rod I6 and its pivotal. connection 1|! to the latch Stop element 14 to hevri ht oithehandlelshaft l2 corresponds to hat in wh ch the. .latchingtelev inents 40 (Fig. 1') of the door a are in their ret-racted or unlatched positions, as will be hereinafter more fully explained.

The latch stop element I4 is provided with a bifurcated portion I4b within which the roller I5 is mounted for rotation upon the pivot pin Ma. The roller I5 is positioned with respect to the axis of the handle shaft I2 such that in one of the said alternate or limit positions o-fthe handle I3, the end of the projecting portion of the element I4 engages the above mentioned stop or detent I8a forming an integral part of the cover I8. In the other of said alternate limit positions of the handle I3, corresponding to the extended position of the latches 40, in which the door is latched to the jamb 28, the roller I5 will engage the other endof the same detent portion I300, as shown in Fig. 5. The handle I3 can, however, only rotate the latching mechanism into this latched position of the door when the door is in the closed position, and the latch stop element I4 is freed or released by the automatic interlocking mechanism, and more particularly by the lockingv or blocking element 25, about to be described.

The blocking element 20 is pivotally mounted for rocking movements within the transverse plane of the roller I5, and that of the latch stop element I4 by which the roller is carried, being .journaled at its pivotal terminals within the base plate In and the housing I8. The element I4 is provided with a detent or recess I40 into which the blocking element 20 is adapted to fit. This rockable lock member 20 extends through the cover I8 and is attached by the screw is to a lever 2|. This lever 2| is pivotally connected to a push-pull rod 24 by means of the pivot pin 22 and is connected at its lower free terminal by the tension spring 23 to the internal stifiening channel 81) at the hooked sprin terminal 23a; thereby tending to continually urge the lever 2I in the counter-clockwise direction into the position shown in Fig. 2. In this position the pushpull rod 24 extends toward the right, or toward the jam 28 of the door, and in this same position the locking element 20 is concurrently urged upwardly against the roller E5.

The spring 23 normally holds the locking element 20 in engagement with the detent i4a and against the roller I5 unless the tension of this spring is overcome by the automatic release means which is provided in the form of a bell crank lever 25, pivotally mounted at 25c upon the lug 8c of the door 8, the bell crank carrying at its outer terminal a pivoted roller 25. -As more clearly shown in Fig. 4, the wall portion is provided with a bevelled jam 28 which has formed thereon the cam or projection 21. This cam is engaged by the roller 26 as the door is moved from its full line open position A into the broken line closed position of the door as indicated at B. It will be noted that as the roller 25 strikes the end face of the cam 21 (as the door is closed) the bell crank member 25 is caused to be rotated in the counter-clockwise direction as viewed in the plan section of Fig. 4. The push-rod 24 is concurrently moved to the left causing the attached lever 2I to be rocked or moved into the position indicated by the construction lines in Fig. 5, in which the locking element 2|] is rotated in the clockwise direction downwardly out of the path or orbit of the projecting portion of the latch stop element I4 and the roller I5.

The mechanism for actuating the bolts or latches 40 for the door is operated by means of the cable drum 32 which is fixedly attached to the handle shaft I2 to rotate therewith. An endless cable 33 extends around the drum 32 as well as around a centrally disposed and somewhat larger diameter drum 34 pivotally mounted upon the pivot 35. Constructed and arranged to rock with the drum 34 are the bridle linkages 3B and 31 which are attached to push-pull cables or other flexible means 38 guided within the sheaths or tubes 39 and having attached at their outer terminals the latch bolts 40. It will accordingly be seen that as either handle I3, or I30, is rotated the cable 33 causes concurrent rotation of the central drum 34, either pushing or pulling the flexible means 38 to extend or retract the latch bolts -40.

The operation of the door latching control mechanism and the automatic interlocking or blocking lock device is as follows:

With the door 8 in its closed position against the jamb 28 of the Wall 7 the roller 26 is in the deflected position toward the door as shown in the broken line position B of Fig. 4 and the push rod 24 and. attached'lever 2| are also moved toward the lert causing the block Zu to be moved into the position shown in Fig. 5 out of the path of the pro ecting portion'of the latch stop element I4 and the roller I5. Accordingly, in the closed and latched position of the door, the element I4 will be in the position shown in Fig. 5 and the position of the interlocking mechanism in the closed position of the door will be that shown in this same figure in which the block 2i! is out of the path of the element I4 and the roller l5. In this closed and latched position of the door and its mechanism as shown in Fig. 5, it is possible to rotate the handle I3 (or the other handle I3a) downwardly or in the counter-clockwise direction in Fig. 5 until the projectin portion of the element I4 strikes the stop Isa, it being only necessary to overcome thecompression in the spring 23 of the quick-acting toggle rod assembly I5. During this rotation of the handle shaft 12, the sheave or drum 32, and its engaged cable 33, cause rotation of the door control mechanism to thereby retract the latch bolts 45. The element I4 and the roller I5, when the latch bolts are fully retracted, assume the position shown in Fig. 2 with the aid of the toggle rod I6 and as the door is then pushed open and the roller 26 rolls oil the end of the cam 27, the tension spring 23 causes the lever 2 l to be rotated toward the right or in the clockwisedirection as viewed in Figs. 2 and 5, and the'blocking element 2!] moves into the detent or recess I40 in the latch stop element I4, blocking any clockwise movement of the element I4, the roller I5 and the attached shaft I2. The door latch control mechanism is therefore locked in its unlatched condition as long as the door is in any other than its fully closed position as determined by the engagement or disengagement of the roller 25 and the cam element 21 on the jamb 28. Accordingly, it is not possible to close the door with the latch bolts 40 in their extended positions.

Other forms and modifications of the present invention both in respect to its general arrangement and the details of its respective parts, which may become apparent to those skilled in the art after reading this description, are all intended to fall within the scope and spirit of the present invention as more particularly defined in the appended claims.

1. Latch mechanism for a door comprising a manually rotatable latch operating means, a bellcrank lever pivotally mounted upon the door upon an axis substantially parallel to the plane of said door, a first arm of said bell-crank lever rotatable into a block position in which it prevents man-ual operation of said latch operating means, resilient means attached to said bellcrank lever urging said first arm portion into said blocking position, stop means fixedly carried by said door for engagement by said manually rotatable latch operating means for defining the extreme limits of movement thereof, springpressed toggle means pivotally interconnecting said manually rotatable latch operating means with said door for snap-action movement of said manually rotatable latch operating means into either of said limit positions whenever manually rotated past an intermediate position and released at such position, and jamb engaging means including a pivotally mounted roller operatively carried by a second arm of said bell-crank lever arranged in such manner that in the closed position of said door, said jamb engaging means imparts rotation to said bell-crank lever thereby overcoming said resilient means and rotating said bell-crank lever into the unblocking position of said first arm portion in which said latch operating means is free to be manually actuated into either its latch extended or latch retracted limit position.

2. Automatic latch blocking means for a door installation including a hingedly mounted door and a wall having a jamb portion defining an opening arranged to be closed by said door, comprising bolt means movably mounted upon said door for latching engagement with said jamb portion, manually rotatable actuating means operatively connected to said bolt means for the extension and retraction of said bolt means, a projecting portion carried by said rotatable bolt actuating means, stop means fixedly carried by said door for engagement by said projecting portion at the extreme limit positions of retraction and extension movements of said rotatable bolt actuating means, spring-pressed toggle means pivotally interconnecting said rotatable actuating means with said door for snap-action movement of said rotatable bolt actuating means into either of said limit positions, blocking means operatively engageablewith said rotatable bolt means for blocking the rotation thereof, strike 6 means fixedly carried by said jamb portion, a bell-crank lever pivotally mounted upon said door on an axis substantially parallel to the plane of said adjacent dopr surface, said bellcrank lever pivotally connected to said blocking means and having a portion in engagementwith said strike means arranged in such manner that upon closing of said door and engagement of said bell-crank lever with said strike means rotation is imparted to said bell-crank lever causing movement of said blocking means into a position in which said manually rotatable bolt means is free for manual rotation into either one of said limit positions in which said bolt means may be extended or retracted.

3. ,Latch mechanism for a door installation including bolt means for latching said door to its jamb, manually rotatable means for operating said bolt means into either its extended or its retracted limit positions, spring-biased toggle means operatively connected to said manually rotatable means for rotating said manually rotatable means into either one of said two limit positions upon release of said manually rotatable means, blocking means operatively engaging said vmanually rotatable means for blocking the rotation thereof, strike means carried by said door jamb, a bell-crank lever pivotally mounted upon said door upon an axis substantially parallel to the surface of said door, said bell-crank lever pivotally connected to said blocking means and having a contacting portion engageable upon closing of said door with said strike means carried by said door jamb arranged in such manner that said bell-crank is rotated thereby imparting movement to said blocking means for the freeing of said manually rotatable means in such manner that said bolt means, may be extended or retracted manually in said closed position of said door.

HAL RAYMOND LINDERFELT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 281,458 Conner July 17, 1883 1,870,746 Pyle Aug. 9, 1932 1,904,970 Cook Apr. 18. 1933 1,996,865 Haag Apr. 9, 1935

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