Dead Bolt Lock

Abstract

A dead bolt lock for use on the interior surface of a door for the entrance of a home or other building adapted for actuation by an exterior tumbler lock or an interior knob, where the dead bolt is projected into a strike or retracted into the lock housing. The lock assembly includes a dead bolt having a pair of rearwardly extending arms, a rotatable knob and a flat spring positioning the knob in either the projected or retracted position of the bolt. The knob includes an internal flange having a camming pin cooperating with a camming surface at the rear end of one bolt arm to reciprocate the bolt and a spaced blocking cam which is moved into a blocking notch formed in the other dead bolt arm when the bolt is projected.

Description

The present invention relates to a novel dead bolt lock having positive operation and providing a unique arrangement of components and an effective manner of obtaining the dead bolt action.

With the present concern for security in homes or buildings to prevent unauthorized entry therein, the use of dead bolt and other security locks or chains has become more prevalent. However, burglars or others attempting unauthorized entry into homes or other buildings have discovered ways to circumvent or force such locks to gain entry for whatever desired purpose. Many dead bolt locks can be released by inserting a camming plate or shim to engage the end of and force retraction of a bolt by jiggling, hammering or similar measures. The present invention provides an improved dead bolt lock which, when in the dead bolt position, will not fail under such jiggling, hammering or other forcible measures.

Among the objects of the present invention is the provision of a novel dead bolt lock having a unique arrangement of components and an effective manner of obtaining the dead bolt feature. The lock includes a reciprocable dead bolt movable between retracted and projected positions and actuated by a rotatable knob. A flat spring has a free end engageable with either one of a pair of spaced notches formed in a flange on the knob to yieldably retain the knob in either of its two positions corresponding to the retracted and projected positions of the dead bolt.

Another object of the present invention is the provision of a novel dead bolt lock having a dead locked position which resists jiggling, hammering or other force exerted on the projected end of the dead bolt. The bolt includes a pair of generally parallel rearwardly extending arms; one arm terminating in a camming recess and the other arm terminating in a blocking notch. The rotatable knob has an interior flange with a camming projection or arm cooperating with the camming recess and a spaced blocking cam received in the blocking notch when the dead bolt is in projected position. The cooperation between the blocking cam and the blocking notch effectively dead locks the bolt in its projected position.

A further object of the present invention is the provision of a novel dead bolt lock where the rotatable knob is rotated through an arc of approximately 90.degree. to reciprocate the bolt between its retracted and projected positions. In the projected position of the bolt, the blocking cam engages the blocking notch in an over-center position so that the only way the dead locked bolt can be released is by turning the knob through the first approximately 15.degree. of rotation to release the blocking cam from its notch. In the remaining approximately 75.degree. of rotation, the camming arm acts upon the camming recess to draw the bolt into its retracted position.

Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

In the drawings:

FIG. 1 is a perspective view of the novel dead bolt lock of the present invention.

FIG. 2 is a rear elevational view of the lock with the base broken away to show the interior of the lock with the bolt retracted.

FIG. 3 is a rear elevational view similar to FIG. 2, but showing the position of the parts with the bolt projected.

FIG. 4 is a horizontal cross sectional view of the lock taken on the irregular line 4--4 of FIG. 3.

FIG. 5 is an enlarged exploded perspective view of the lock parts and a portion of the base.

FIG. 6 is a rear elevational view of the lock with the bolt projected.

FIG. 7 is a rear elevational view of the dead bolt.

FIG. 8 is a front elevational view of the dead bolt.

FIG. 9 is a horizontal cross sectional view of the dead bolt taken on the line 9--9 of FIG. 7.

FIG. 10 is a rear elevational view of the rotatable knob.

FIG. 11 is a horizontal cross sectional view of the knob taken on the line 11--11 of FIG. 10.

Referring more particularly to the disclosure in the drawings wherein is shown an illustrative embodiment of the present invention, FIG. 1 discloses a dead bolt lock 10 having a housing 11 with a front or inner wall 12, side walls 13, a closed end wall 14 and an opposite end wall 15 having an opening 16 for a reciprocable dead bolt 17 which is projected into a suitable strike 18 (FIGS. 2, 3 and 4). The housing 11 includes openings 19 at the four corners extending through the front wall 12 and through tubular extensions 20 in the housing to receive suitable fastening means, such as screws, to secure the housing to the interior surface of a door 21.

A base 22 is received within the housing with a tongue 23 received in the opening 16 in the end 15 and openings adjacent the corners 24 to receive the inner ends of the tubular extensions 20 which are shouldered at 25 and swaged over at 26 to retain the base in the housing. The base includes a depending spacing tab 27 engaging a projection 59 in the housing adjacent one side wall 13, a generally central opening 28 to receive the inner end 47 of a rotary knob 43, and an elongated guide slot 29 for a purpose to be later described.

The dead bolt 17 has a solid bolt body 31 with a pair of rearwardly extending generally parallel arms 32 and 33. As more clearly shown in FIG. 8, the arm 32 terminates in a lateral rear end 34 providing a lateral camming recess 35 defined by a rear flat wall 36 and a forward wall having an outer parallel portion 37 and an angularly disposed inner portion 38. The other arm 33 terminates in a rear offset and angularly disposed end 39 defining an angularly disposed blocking notch 41. As seen in FIG. 4, the arm 33 is centrally disposed relative to the bolt body 31 and the arm 32 is located flush with the rear edge of the bolt body 31. A guide pin 42 is formed on the arm 32 on the opposite side from the recess 35 and is received in the slot 29 in the base 22 to guide reciprocating movement of the bolt 17.

A rotatable knob 43 (see FIGS. 1, 10 and 11) includes a generally cylindrical body with a manual gripping portion 44, an intermediate flange 45 and a rearwardly extending central sleeve-like knob portion 46 of a reduced diameter with the reduced end 47 of the portion 46 extending into the opening 28 of the base 22. The end 47 of the portion 46 has an opening 48 with inwardly extending shoulders 49 to receive and cooperate with a conventional tailpiece for a key-actuated tumbler lock (not shown) mounted in the exterior surface of the door 21 with the tailpiece extending through the door and into the opening 48. The arms 32 and 33 of the dead bolt 17 form a slot or channel 51 to encompass the knob portion 46.

The intermediate flange 45 has a pair of identations or notches 52 and 53 spaced by an arc of approximately 90.degree., and generally opposite those notches is a projecting portion or extension 54 having a camming pin 55 and a spaced blocking cam 56. The camming pin 55 extends rearwardly from the flange into the lateral recess 35 on the arm 32 to actuate the dead bolt 17, and the blocking cam 56 cooperates with the blocking notch 41 as will be later described.

A flat spring 57 (FIGS. 2, 3 and 5) has a U-shaped end 58 encompassing the short projection 59 projecting inwardly from the front wall 12, and the opposite end 61 of the spring has a curved detent cooperating with the spaced indentations 52 and 53 on the intermediate flange 45 to yieldably position the knob 43 at the end limits of travel of the dead bolt 17.

FIG. 2 discloses the dead bolt lock 10 in its normal unlocked or retracted position with the dead bolt 17 completely retracted within the housing 11; the outer end of the bolt being flush with the end wall 15. In this retracted position, the arms 32 and 33 forming the slot 51 partially encompass the central portion 46 of the knob 43 and the camming pin 55 is located within the camming recess 35 abutting the rear wall 36. Also, the detent end 61 of the spring 57 engages the detent notch 52 in the knob flange 45 to yieldably retain the knob and bolt in retracted position.

To actuate the dead bolt 17, the knob 43 is manually rotated by the gripping portion 44 in a clockwise direction as seen in FIG. 2 so that the camming pin 55 will engage the parallel wall portion 37 and urge the arm 32 and bolt 17 towards the projected position shown in FIGS. 3 and 4; the detent end 61 of the spring 57 moving out of the notch 52. As the knob 43 is rotated, the camming pin 55 moves up the parallel wall portion 37 to the angularly disposed inner portion 38 to project the bolt into the strike 18 to its deadlocked position. For the last approximately 15.degree. of rotation of the knob 43, the camming pin 55 is out of contact with the arm 32 and the blocking cam 56 is moved into the blocking notch 41 in the arm 33 and the spring detent end 61 engages the spaced notch 53.

With the bolt 17 and knob 43 in the position shown in FIG. 3, the bolt cannot be retracted or caused to fail by jiggling, hammering or other force exerted on the bolt's end. The blocking cam 56 positioned in the notch 41 is in an over-center position relative to the axes of the knob and the bolt to prevent unauthorized retraction of the dead bolt, so that the actual destruction of the parts in contact is required to retract the bolt by pressure applied to the end of the bolt. Rotation of the knob 43 in a counterclockwise direction, as seen in FIG. 3 will retract the bolt, with the first approximately 15.degree. of rotation releasing the dead lock engagement between the blocking cam 56 and the notch 41. For the remaining approximately 75.degree. of rotation, the camming pin 55 enters the recess 35 and engages the wall 36 of the arm 32 to retract the bolt to the position of FIG. 2. The guide pin 42 moving in the slot 29 provides for straight reciprocable movement of the bolt without canting thereof.

The dead bolt 17 can obviously be actuated to either position by actuation of a key-operated tumbler lock (not shown) at the exterior surface of the door 21 where rotation of a rotary plug by a proper key causes rotation of a conventional tailpiece extending through the door into the opening 48 and cooperating with the shoulders 49,49 to rotate the knob 43. Rotation causes the tailpiece to engage two oppositely disposed surfaces on the shoulders 49,49 to rotate the knob, and the spacing of the shoulders allows for suitable lost motion to return the key to its normal position where it can be removed from the tumbler lock.

Claims

I claim:

1. A dead bolt lock assembly to be secured onto a door and cooperate with a suitable strike in a door frame therefor, comprising a housing to be secured onto the door opposite the strike, a reciprocable dead bolt in the housing movable between retracted and projected positions, a rotatable knob mounted for limited rotation in the housing, said knob having an enlarged flange located within the housing, cooperating camming means on the knob, said camming means including a camming pin on the flange, said dead bolt having at least one rearwardly extending arm terminating in a camming recess receiving the camming pin, said camming recess extending laterally with a flat rear wall and a forward wall with a flat outer portion and an angularly disposed inner portion to actuate the dead bolt upon rotation of the knob, and blocking means on the knob adapted to move into a cooperating position with the dead bolt to dead lock the dead bolt in projected position.

2. A dead bolt lock assembly as set forth in claim 1, in which said dead bolt has a rearwardly extending arm terminating in an angularly disposed blocking notch, and said blocking means includes an angularly disposed blocking cam integral with said knob and movable into said blocking notch upon rotation of the knob when the dead bolt is in projected position.

3. A dead bolt lock assembly as set forth in claim 2, in which said blocking cam is in an over-center position when positioned in the blocking notch to prevent unauthorized retraction of the dead bolt.

4. A dead bolt lock assembly as set forth in claim 1, including detent means to yieldably position the knob in a position of rotation corresponding to the retracted or the projected position of the dead bolt.

5. A dead bolt lock assembly as set forth in claim 4, in which said knob has an enlarged flange located in the housing with a pair of notches formed in the edge thereof and spaced on an arc of approximately 90.degree., and said detent means includes a flat spring secured at one end in the housing and having an opposite detent end biased against and engaging the flange and the spaced notches to yieldably retain the knob in either position of rotation.

6. A dead bolt lock assembly to be secured onto a door and cooperate with a suitable strike in a door frame, comprising a housing to be secured onto the door opposite the strike, a reciprocal dead bolt in the housing movable between retracted and projected positions, said dead bolt including a pair of rearwardly extending, generally parallel arms, a rotatable knob mounted for limited rotation in the housing, camming means including a camming pin attached to said knob, a camming recess on the inner end of one dead bolt arm receiving the camming pin, said dead bolt being actuated by rotation of said knob and engagement of said pin and recess, a blocking notch formed on the inner end of the other dead bolt arm, a blocking cam also formed on said knob for engagement with said blocking notch only when said dead bolt is in a projected position, and means for engaging said knob and maintaining said knob in a position with said dead bolt fully projected or fully retracted.

7. The assembly of claim 6 wherein said means for maintaining comprises a flange on said knob having notches and also including spring detent means mounted in said housing for engaging a notch and maintaining said dead bolt in a projected or retracted position.

8. A dead bolt lock assembly as set forth in claim 6, in which said camming pin acting in said recess actuates the dead bolt from retracted to projected position during the first approximately 75.degree. of rotation of the knob and the blocking cam moves into the blocking notch during the next approximately 15.degree. of rotation to position the blocking cam in an over-center position.

9. A dead bolt lock assembly as set forth in claim 6, in which said knob extends through the housing, and the rearwardly extending arms on the dead bolt provide a central slot adapted to encompass the portion of the knob within the housing.