IP Library Granted Patent US 12663294
Granted Patent B2
US 12663294 · App. 18/102,540 · Granted Jun 23, 2026

Self-testing fire door

Inventors: Jake Melvin (Yeovil, GB); Warwick Melvin (Yeovil, GB)
Assignee: Harmony Fire Ltd.
G01D5/145A62C2/12E06B5/16
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Quick Facts
Patent No.
US 12663294
App. No.
18/102,540
Granted
Jun 23, 2026
Kind
B2
Abstract

Once a fire door has been installed, the door will typically require regular inspection to ensure that the fire door is still able to operate as intended. An issue typically seen with fire doors is related to the gaps between the door and the frame that being too large. The present disclosure provides a self-testing fire door system comprising a first distance sensor arranged to measure a first distance between a fire door and a door frame. The first distance sensor comprises a first sensor member arranged on the door frame and a second sensor member arranged on the fire door adjacent to the first sensor member when the fire door is in a closed position. The system further includes a processor configured to measure, via the first distance sensor, a distance between the fire door and the frame and output the first distance.

Claims (33)

1 . A self-testing fire door system comprising:

a door frame;

a fire door attached to the door frame via one or more hinges, wherein the fire door is moveable between a closed position, in which the fire door covers an opening in the door frame, and an open position, in which the opening in the door frame is uncovered;

a first distance sensor arranged to measure a first distance between a top portion of a non-hinged side of the fire door and the door frame, wherein the first distance sensor comprises a first sensor member arranged on the door frame and a second sensor member arranged on the fire door adjacent to the first sensor member when the fire door is in the closed position, wherein the first distance sensor and the second distance sensor are in communication via a hardwired connection, and wherein the first distance sensor comprises an analogue to digital converter; and

a processor configured to:

measure, via the first distance sensor, the first distance; and

output the first distance;

wherein the first distance sensor comprises three Hall effect sensors arranged such that each Hall effect sensor is aligned along different axes to each of the other Hall effect sensors in a triaxial arrangement,

wherein the system further comprises a second distance sensor arranged to measure a second distance between a bottom portion of the non-hinged side of the fire door and the door frame, wherein the second distance sensor comprises a first sensor member arranged on the door frame and a second sensor member arranged on the fire door adjacent to the first sensor member when the fire door is in the closed position,

wherein the first distance is a first distance between a first surface at the top portion of the fire door and a portion of the frame, and the second distance is a second distance between the first surface at the bottom portion of the fire door and the portion of the frame, and

wherein the processor is further configured to detect a warp or twist in the door or frame based on the measured first and second distances.

2 . The system of claim 1 , wherein the first distance sensor is a node sensor and the second distance sensor is an auxiliary sensor.

3 . The system of claim 1 , wherein the processor is configured to output the first distance is response to the fire door moving to the closed position.

4 . The system of claim 3 , wherein the system comprises a closure sensor configured to provide an output when the door is moved to the closed position.

5 . The system of claim 3 , wherein the system comprises an inertial measurement unit.

6 . The system of claim 1 , wherein the processor comprises a time keeping unit and the processor is configured to output the first distance after a predetermined time interval.

7 . The system of claim 6 , wherein the processor is configured to continually output the first distance at regular time intervals, wherein the regular time interval is at least every second.

8 . The system of claim 1 , wherein the processor is configured to output the first distance to an alert unit, wherein the alert unit is configured to compare the first distance to a predetermined maximum allowable first distance and output an alert if the first distance exceeds the predetermined maximum allowable first distance; and

wherein the predetermined maximum allowable first distance is user settable and/or resettable.

9 . The system of claim 1 , wherein:

the processor is configured to keep a log of each measurement of the first distance; and

the processor is Internet-enabled and the log is remotely accessible.

10 . The system of claim 1 , wherein the processor is configured to calculate a distance between the fire door and the door frame in three dimensions based on triangulation of the signals from the three sensors or based on a vector-based calculation.

11 . The system of claim 1 , wherein the system further comprises a power source configured to provide power to the first distance sensor and the processor.

12 . The system of claim 1 , further comprising a hub in communication with the processor, wherein the hub is further configured to communicate with further processors of further self-testing fire door systems.

13 . The system of claim 1 , wherein the first distance sensor has an operational range of between 5 mm and 20 mm; and

wherein the first distance sensor has a resolution of less than 0.05 mm.

14 . A method of testing the fire door system of claim 1 , the method comprising:

measuring the first distance;

comparing the first distance to a predetermined maximum allowable first distance;

measuring the second distance;

detecting the warp or twist in the door or frame based on the measured first and second distances; and

outputting a detection of the warp or twist in the door.