Door position indicator for a door closer
BACKGROUND OF THE INVENTION 
     The present invention relates to an on-board door position indicator that is part of a package including a modified door closer. It is intended to be used in high security locations, such as jails, where it will control the ceiling and/or corridor or other security doors and send a signal to a security office or monitor as to the closed or open condition of the door. The unit is concealed in the head frame or possibly, alternatively, the door still of the doorway with the door track concealed in the top or bottom of the door as the case may be. Since the entire unit is concealed within the door frame, or door itself, the device is vandalproof when the door is closed. The object of the invention, therefore, is to provide a simple, safe and reliable means of both closing a security door and advising as to its open or closed condition in a reliable vandalproof manner. These and other objects are obtained in a door control and position sensing device comprising: 
     A door closer housing having a piston disposed within said housing for movement proportionately associated with a door; means for sensing the position of the piston at at least one point in its travel as a means of determining the position of the piston and thereby the associated door position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a partially sectioned side elevation of a door closer and position sensing device according to the present invention. 
     FIG. 2 shows a stop or plan view of the closer portion and its associated position sensing switch. 
     FIG. 3 is a cross section detail of the trip rod according to the present invention. 
     FIG. 4 is an end view of the closer track as viewed from FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a modified conventional door closer is shown, such as manufactured by LCN Closers, a division of Schlage Lock Company. The particular door closer shown in FIG. 1 has two independent adjustable closing speed zones, an adjustable backcheck zone and adjustable spring power to control the door in the opening and closing swings. 
     An on-board door position indicator switch relays a signal to a remote control station indicating whether the door is open or closed, and also can be connected to the circuit which controls and reports the status of the door lock and bolt condition. 
     The door closer body 1, is connected to the door with a tamper resistant arm 2, and roller 3, that traverses a track 4, concealed in the top of the door. A wiper 5, at the arm/roller connection clears foreign objects in the path of the roller 3, by expelling debris from either open end of the track (best seen in FIG. 4); or by raising the debris out of the track along sloped ramp 6 at the end(s) of track 4. 
     The closer end of arm 2, is attached to the closer pinion shaft 7. Rotation of pinion 7, moves piston 8, laterally in the closer cylinder body as the door opens and closes. When piston 8, moves to the left during the door opening swing, flange end 9a, of trip rod 9b, follows piston 8, until stop ring 10 abuts reservoir case 11, or spring 12 relaxes ending the lateral movement of the trip rod assembly 9. This translation of trip rod 9b, supported by bushing 23, away from switch 13, reverses the contacts in the switch sending a signal through the normally closed/normally open circuit that the door has been moved from the closed position. conversely, as the door closes, the track 4, roller 3, arm 2, and pinion 7, combination moves the piston 8 to the right. As the door nears the closed position, piston head 8a, abuts flange 9a, of trip rod assembly 9, depressing return spring 12 (see detail in FIG. 3), while urging trip rod 9b, against switch 13, switching the circuit to send a signal that the door is closed. 
     An overtravel feature beyond the trip point of switch 13, allows additional movement of trip rod 9b, without changing the status of the signal circuit. This advantageous feature permits the door to be moved in and out within the confines of the door locking bolt (door rattle) in the lock strike without sending a door open signal. 
     Switch mounting base 14 (best seen in FIGS. 1 and 2) can be moved laterally along slotted holes 14a, to adjust the location of switch 13, with respect to trip rod 9b, and is secured with screws 15. Switch 13 is supported by switch channel 16 which is pivotally hinged at its right end to switch mounting base 14. Torsion spring 17, mounted at the pivot point, exerts sufficient pressure to hold switch channel 16, against adjusting screw 18. Adjusting screw 18, locates switch 13, vertically with reference to trip rod 9b, to provide a fine tuning adjustment for the installer that permits him to selectively choose the point during the closing of the door where a signal will be given that the door is at a predetermined distance from the door stop (closed position). 
     It is important that during the door opening cycle the hydraulic fluid within the closer cylinder be permitted to flow freely through ball check valve 19, to the low pressure side of piston head 8a. A hole 20, has been provided in trip rod flange 9a, to assure this free flow even when flange 9a, abuts piston head 8a. 
     Seals 21, typically shown as, but not restricted to O-rings, are used to confine the hydraulic fluid within the door closer cylinder. It is recognized that eventually all seals may seep fluid and therefor reservoir case 11, has been provided to receive any fluid that may seep along trip rod 9a. 
     An additional seal 22, shown as an O-ring, is mounted on trip rod 9b, to serve as a barrier to capillary action of fluid along the trip rod. If any fluid seep creeps along trip rod 9b, it will be stopped at barrier seal 22, and drip into reservoir case 11. 
     Having described my invention in terms of a preferred embodiment we do not wish to be limited in the scope of our invention except as claimed.