AU777279B2 - Improvements in electric drop bolts - Google Patents

Description

-1AUSTRALIA.& PATENTS ACT 1990 COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. CI: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: Trimec Technology Pty. Ltd.

Address of Applicant: Actual Inventor: 5/23 Resolution Drive Caringbah NSW 2229 Graham James Luker Address for Service: ANDERSON-TAYLOR ASSOCIATES, Registered Patent of 10 Harrison Avenue BONNET BAY N.S.W. 2226 Attorneys Complete Specification for the invention entitled: IMPROVEMENTS IN ELECTRIC DROP BOLTS The following statement is a full description of this invention, including the best method of performing it known to me: This invention relates to security locks. More particularly although not exclusively it discloses an improved electric drop bolt.

The purpose of a drop bolt is to provide a concealed lock for a door or other movable barrier. In prior art devices a solenoid moves a pin axially out from the doorway frame and into a faceplate set in the edge of the door. The faceplate has an aperture dimensioned to slidably receive the pin so that once it is in place the door is effectively locked. Such devices are generally used where security is desired but the installation is to be invisible when the door is locked.

There are however a number of problems with the devices S"currently in use. If there is any misalignment of the door in the frame the bolt will hit the faceplate rather than seat in the hole. While with some systems the bolt will pulse for a limited time the door still will only lock if the faceplate hole is precisely aligned with the bolt. There is a further problem with releasing a locked door if any side loads are imposed from air pressure differentials, persons pressing against the door or door warpage etc. In such cases the bolt S• becomes jammed in the hole and cannot be withdrawn by the solenoid. The power required by solenoids to slide the bolt into and out of the locking aperture is also excessive.

It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly an electric lock for a door is disclosed, said lock including a housing -2adapted for mounting into the doorway frame, said housing having a tongue pivotal therein by a mechanical drive between a locking position wherein said tongue extends out from said doorway frame to engage in an aperture in the edge of said door and an unlocked position where said tongue is withdrawn into said housing so as to clear said door, said mechanical drive including a screw shaft rotatable by an electric motor to move a roller nut along the length thereof whilst engaging a cam surface on said tongue.

Preferably said drive mechanism is set in a cage pivotal between a tongue engaging position and a tongue disengaged position It is further preferred that said tongue include a roller to facilitate its entry into a tapered faceplate slot in the door.

The currently preferred form of this invention will now be ooooo: described with reference to the attached drawings in which: Figure 1 is a cross-sectional side view of the lock when in the latched configuration, Figure 2 is view similar to figure 1 but with the lock in the unlatched configuration, and Figure 3 is a plan view of the preferred form of door faceplate for use with the lock of figures 1 and 2.

Referring first to figures 1 and 2 there is shown an electric lock comprising a housing 1 which is adapted for mounting into a doorway frame with plate 1A facing outward. The housing has a tongue 2 pivoted about a pin 3 so that it can move between the locking position shown in figure 1 where it extends out from the frame and an unlocked position (figure 2) where it is substantially within the housing. The mechanical drive for the tongue comprises a electric motor 4 which turns a screw shaft 5 through a reduction gear box 6.

Mounted on the screw shaft 5 is a roller nut 7 which moves along the length of this screw as it is rotated by the motor.

The roller nut 7 in turn engages a cam surface 8 attached to the tongue 2. In accordance with the direction of motor rotation the nut 7 moves either to the left (figure 1) to extend the tongue out to lock the door. or to the right (figure 2) to withdraw the tongue and release the door.

Preferably the tongue is spring biased to the withdrawn or unlocked position.

oooo• In order to provide for "Fail Safe" operation the drive assembly is mounted in a cage 9 which is pivoted within the S• housing at one end 10. An electromagnet 11 is also fitted inside of the housing at a location remote from the pivoted end 10. When energised it retains the cage in the engaged position shown during operation of the drive mechanism on the tongue. With the lock engaged minimal power only is then required to enable this electromagnet 11 to retain the cage in this position. To obtain the "Fail Safe" function all power is removed whereby the electromagnet 11 releases the cage 9 to pivot upwards to a disengaged position so that the roller nut 7 clears the cam surface 8 and the tongue 2 pivots inward under the spring bias mentioned earlier.

Although not shown in the drawings an auto latching device may be fitted which retains the cage 9 in the engaged position without the electromagnet, but releases upon pulsing of said magnet. This allows the lock to operate on a "Fail Secure" mode while still retaining an emergency function which releases the cage 9 when the electromagnet 11 is pulsed from an external battery. Such emergency opening function is c. totally absent from prior art solenoid operated drop bolts.

To further enhance the locking mechanism the tongue 2 as mentioned earlier is preferably fitted with a roller 11A and the door faceplate 12 (as shown in figure 3) is formed with a tapered slot 13. This allows the tongue 2 to enter the aperture at the widest point 13A and then roll to the narrow locking end 13B. Door location is therefore less critical than with prior art drop bolt mechanisms as the action of the roller tongue within the slot aligns the door to the correct position. The roller and shape of the slot further facilitates withdrawal of the tongue even when the door is under load.

It is still further preferred that the faceplate 12 has a concealed magnet 14 preferably located about the centerline and the lock housing be provided with a reed switch positioned to be activated by said magnet as the door is closed. This turns the motor 4 on to operate the drive and lock the door as described earlier. To unlock the door the motor is reversed so that the roller nut 7 together with the spring bias withdraws the tongue, With this embodiment there is also a sensing bar 16 which moves with the roller nut 7 to limit the travel of said nut.

The electronics currently under development for the lock will sense the position of the tongue 2 so that the unlocked and "'locked positions can be operated from a typical external access control system. Should any overload occur the system would preferably be adapted to switch the motor to the open position and retry.

It will thus be appreciated that this invention at least in the form of the embodiment disclosed provides a novel and useful improvement to drop bolt locks. The benefits over prior art mechanisms include the following: oo- the interaction of the tapered faceplate aperture and pivoting roller tongue assists in locating the door to the locking position, the operating mechanism requires less current than solenoid operated receprocating bolt systems while still producing greater driving force on the tongue due to the use of reduction gears and screw shaft.

-6there is an emergency release available in the "Power to Open" or "Fail Secure" mode, the tongue will not stick or jam due to dirt in the aperture or side pressure on the door, the lock is suitable for overhead or side mounting, an auto reset is preferably provided if the motor overheats, full monitoring is preferably provided, and the lock is suitable for narrow styling.

Clearly however the example described is only the currently preferred form of the invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the shape and configuration of the housing, pivoting tongue and faceplate aperture as well as the arrangement of the mechanical drive could be changed according to application or design preference.

PP. oo,

Claims (9)

1. An electric lock for a door closable in a doorway frame. said lock including a housing adapted for mounting into the doorway frame, said housing having a tongue pivotal therein by a mechanical drive between a locking position wherein said tongue extends out from said doorway frame to engage in an aperture in the edge of said door when closed and an unlocked position where said tongue is withdrawn into said housing so as to clear said door, said mechanical drive including a screw shaft rotatable by an electric motor or solenoid to move a roller nut along the length thereof whilst engaing a cam surface on said tongue.

2. The electric lock as claimed in claim 1 wherein said nut moves along said screw shaft in a direction either to pivot said tongue to said locking position or to pivot said tongue to said unlocked position in accordance with the direction of rotation of said screw shaft.

3. The electric lock as claimed in claim 2 wherein said mechanical drive is set in a cage pivotal between an engaged position at which the roller nut engages said cam surface and a disengaged position at which the roller nut is clear of said cam surface whereby said tongue pivots to said unlocked position under a spring bias.

4. The electric lock as claimed in claim 3 wherein an electromagnet is fitted which retains said cage at the engaged position when said electromagnet is energised and releases said cage when power is removed.

The electric lock as claimed in claim 4 wherein said lock is fitted with an auto latching device which retains the cage at the engaged position when power is removed but releases said cage upon pulsing of said electromagnet.

6. The electric lock as claimed in claim 5 wherein said tongue is fitted with a roller and said aperture consists of .a tapered slot in a faceplate whereby the tongue when moving to said locking position enters at the widest end of said slot and then rolls to the narrow end thereof.

7. The electric lock as claimed in claim 6 wherein said faceplate has a concealed magnet and the lock housing has a reed switch positioned to be activated by said magnet as the door is closed whereby said electric motor is turned on to move said tongue to the locked position. S•

8. The electric lock as claimed in claim 7 wherein said lock is fitted with a sensing bar which limits the travel of said nut.

9. The electric lock as claimed in claim 8 wherein said electric motor rotates said screw shaft through a reduction gear box. The electric lock as claimed in claim 9 wherein said lock is adapted for use with electronics which senses the position of the tongue so that the unlocked and locked positions can be operated from an external access control system. Dated this /F day of 6 ~i~'Z 2000 Trimec Technology Pty. Ltd. By Their Patent Attorney MICHAEL ANDERSON-TAYLOR S S S S S S *5S5 S S S