Elevator rotary door interlock

Abstract: An elevator door interlock (18) has a cam having camming surfaces (58,60,62,64) which are in contact with leads (38) of an electrical circuit during normal operation and a bridge (46) thereon. The cam rotates the camming surfaces along the leads such that the leads contact the bridge if an elevator door (12) is locked, such that they do not contact the bridge if the elevator door is not locked, and rotates the camming surfaces and bridge out of contact with the leads if the door is missing.

Description: Passenger elevators generally have a car having a pair of doors and a landing having a pair of hoistway doors. Both the car and hoistway doors open and close approximately in register with each other to allow passengers to enter and exit the elevator car. When the car is not at the landing, the hoistway doors must be locked and in place to protect passengers standing at the landing from entering the elevator hoistway. It is a safety requirement to equip the hoistway doors with a lock and an electrical contact (or "interlock") to ensure that the doors are positively locked. Furthermore, it may also be a requirement to ensure that the doors are not missing or lost. A door may be taken off (i.e. missing) for service or due to some accident. A typical lock consists of a latch attached to a hoistway door and a catch attached to a hoistway header. A typical open electrical circuit interlock consists of a pair of blade springs attached to the catch, and a bridge attached to the latch. If the hoistway doors are closed, the latch engages the catch and bridges the open electrical circuit. The completed electrical circuit sends a signal to a controller which indicates that the doors are locked and it is therefore safe to move the elevator car. However, when the bridge engages the electrical circuit, excessive noise may result. Further, the bridge may bounce away from the electrical circuit, which may lead to maintenance and operation problems. It is an object of the invention to provide a reliable, relatively trouble-free interlock. It is a further object of the invention to provide an interlock which operates in a relatively noise free manner. It is a further object of the invention to provide a new lost door detector. According to the present invention, there is provided an elevator door interlock which bridges leads of an electrical circuit to indicate that the elevator door is locked, said interlock comprising a rotatable cam having insulated camming surfaces contacting said leads, and a conductive bridge disposed upon said cam, said cam rotating the bridge into contact with the leads if said door is locked and out of contact with the leads if the door is not locked. The elevator door interlock of the present invention has a cam having camming surfaces which are in contact with leads of an electrical circuit during normal operation and a bridge thereon. The cam rotates the bridge into contact with the lead if an elevator door is locked and out of contact with the leads if the elevator door is not locked. Because the camming surfaces are always in contact with the leads, there is relatively little contact noise and a minimal probability that the interlock bridge bounces away from the leads. According to a feature of the invention, each lead slides in a groove between the camming surfaces when the door is open. The groove prevents the material of the camming surfaces from contaminating the surface of the lead which engages the bridge thereby improving the electrical contact between the lead and the bridge and the life of the interlock. Preferably, the cam rotates the camming surfaces along the leads such that the leads contact the bridge if an elevator door is locked, such that they do not contact the bridge if the elevator door is not locked, and rotates the camming surfaces and bridge out of contact with the leads if the door is missing. These and other objects, features, and advantages of the present invention will become more apparent in light of the following detailed description of an embodiment thereof, given by way of example only, as illustrated in the accompanying drawings. Fig. 1 is a front view of a hoistway door lock employing an interlock of the invention; Fig. 2 is a perspective view of the interlock of Fig. 1; Fig. 3 is a side view of the interlock of Fig. 1 if the hoistway door is open; Fig. 4 is a side view of the interlock of Fig. 1 if the hoistway door is closed; and, Fig. 5 is a side view of the interlock of Fig. 1 if the hoistway door is missing. Referring to Figure 1, an elevator hoistway door lock 10 employing an embodiment of the interlock of the invention is shown. The hoistway door lock shown is typically utilized with an elevator car (not shown) which has a retiring cam (not shown) which moves the hoistway door lock out of contact with a hoistway door 12 as is known in the art. The door has a bumper bracket 13 mounted thereto as will be discussed infra. The hoistway door lock 10 comprises a brace 14 attached to a hoistway (not shown), a bracket 16, an interlock 18, and a locking linkage 20. The locking linkage 20 comprises a rotatable shaft 22 having a first end portion 24 and a second end portion 26. An arm 28, an axle 30, and a cam following roller 32 are fixedly attached to the first end portion. A locking tab 34 is fixedly attached to the second end portion. The locking tab 34, the arm 28, the axle 30, and the roller 32 all rotate with the shaft 22. The brace 14 has a pair of journal bearings 35 which rotatably support the shaft 22. The bracket 16 is attached to the brace between the journal bearings 35. The brace has a downwardly extending flange 36 (see also Figs 3-5) which acts as a spring seat as will be discussed infra. The bracket 16 holds a pair of electrical leads 38 (see also Figs. 3-5). The leads are part of an electrical circuit (not shown) which, when closed, signals a controller (not shown) that the doors are properly locked as is known in the art. Each lead 38 has a button contact 40 riveted thereto as is known in the art. Referring to Fig. 2, the interlock 18 is shown. The interlock comprises a first plastic half 42, a second plastic half 44 and a bridge 46. The first plastic half has a u-shaped cross-section and a pair of legs 48 extending therefrom. Similarly, the second plastic half has a u-shaped cross-section and a first leg 50 and a second leg 52 extending therefrom. The u-shaped cross-sections of the first and second halves enclose the shaft 22 when they are attached together by rivets 54 or the like. A spring 55 impinges against the first leg 50 and the flange 36 against motion of the retiring cam (not shown). The second leg 52 of the second half 44 has a platform 56 having a first camming surface 58, a second camming surface 60, a third camming surface 62, a fourth camming surface 64, and a rectangular indentation 66 for receiving the bridge 46. A first channel 68 is formed between the first and second camming surfaces and a second channel 70 is formed between the third and fourth camming surfaces. The channels have sufficient width and depth to allow edges of the contact buttons 40 to travel along the edges of the respective camming surfaces 58-64. By allowing the buttons to travel along their edges, the portion of the buttons that contact the bridge do not contact the plastic material of the interlock thereby avoiding the transfer of any of that material to the button. Contact between each button contact 40 and the bridge 46 is therefore metal-to-metal, ensuring long life and reliability. The bridge 46 has a first layer 72 of a conductive material, such as copper, and a second layer 74 of a highly conductive material such as silver. The second layer 74 has a first raised contact portion 76 and a second raised contact portion 78 for engaging the buttons 40. The first raised portion aligns with channel 68 and the second raised contact portion aligns channel 70. The bridge is attached to the platform 56 within the rectangular indentation 66 by a screw 80 or the like. Referring to Figs 3-5, the operation of the switch is shown. If the locking linkage 20 is rotated by the retiring cam (not shown), the locking tab 34 rotates in the clockwise direction out of the way (see Fig. 3) of the door 12 to allow it to open. The interlock 18 is rotated in the clockwise direction out of contact with the leads thereby breaking the circuit to signal the controller that the hoistway doors are open thereby preventing the car from moving. The spring 55 is compressed by the rotation of the interlock. If it is time to move the car (referring to Fig. 4), the retiring cam is withdrawn and the locking linkage 20, due to the force of spring 55 and gravity force acting on the roller 32, rotates in the counterclockwise direction to move the locking tab 34 into contact with the hoistway door bumper bracket 13, thereby locking the door 12 closed. The interlock is also rotated in the counterclockwise direction with the shaft thereby moving the contact buttons along the edges of the channels until they contact the raised portions 76, 78 of the bridge 46 thereby closing the circuit to signal the controller that the hoistway doors are closed and that therefore the car may move safely. The camming surfaces may be shaped to allow the leads to drop, as opposed to sliding, onto the raised portions 76, 78 of the bridge to avoid scraping contact that might wear the raised portions away thereby limiting the life of the bridge 46. As above, if it is time to move the car (referring to Fig. 5) and for some reason the hoistway door is missing or lost, the retiring cam is withdrawn and the locking linkage 20, due to the force of spring 55 and gravity force acting on the roller 32, rotates in the counterclockwise direction intending to move the locking tab 34 into contact with the bumper bracket of the door 12, but the door is missing. The interlock is also rotated in the counterclockwise direction with the shaft 22 thereby moving the bridge beyond contact with the leads 38 thereby opening the circuit to signal the controller that the hoistway doors are not closed and that therefore the car may not move safely.

Claims: An elevator door interlock (18) which bridges leads (38) of an electrical circuit to indicate that the elevator door (12) is locked, said interlock comprising: a rotatable cam having insulated camming surfaces (58,60,62,64) contacting said leads, and a conductive bridge (46) disposed upon said cam, said cam rotating the bridge into contact with the leads if said door is locked and out of contact with the leads if the door is not locked. The interlock of claim 1 in which said cam rotates said bridge to a first position wherein said leads are in contact with said camming surfaces if the door (12) is not locked, to a second position wherein said leads are in contact with said bridge (46) if the door is locked, and to a third position wherein said leads are out of contact with said camming surfaces and said bridge if the door is missing. The interlock of claim 1 or 2 wherein said cam has grooves (68,70) defining edges over which first portions of said leads (38) slide such that second portions (40) of said leads that contact said bridge (46) do not contact said camming surfaces, thereby improving the electrical contact between said leads and said bridge and the life of the interlock. The interlock of claim 1, 2, or 3 wherein said bridge is recessed within said cam below said camming surfaces to minimize wear upon said bridge. An elevator door lock (18) which bridges leads (38) of an electrical circuit to indicate that the elevator door (12) is locked, said interlock comprising: a rotatable conductive bridge (46), and means for rotating said bridge, said means rotating said bridge to a first position relative to said leads if said door is locked, said means rotating to move said bridge to a second position relative to said leads if said door is not locked, said means rotating said bridge to a third position relative to said leads if the door is missing. The interlock of claim 5 wherein: said first position puts the leads (38) in contact with said bridge (46), said second position puts the leads out of contact with said bridge, and, said third position puts the leads out of contact with said bridge. The interlock of claim 5 or 6 wherein said means for rotating said bridge comprises a rotatable cam having insulated camming surfaces (58,60,62,64) and said bridge disposed thereon. The interlock of claim 7 wherein: said first position puts the leads in contact with said bridge, said second position puts the leads in contact with said camming surfaces but not said bridge, and, said third position puts the leads out of contact with either of said camming surfaces or said bridge.

Inventors: DONOHOE MICHAEL P, KULAK RICHARD E, TONNA CHRISTIAN G, DONOHOE, MICHAEL P., KULAK, RICHARD E., TONNA, CHRISTIAN G.
Applicants: OTIS ELEVATOR CO, OTIS ELEVATOR COMPANY
Application year: 1993
Main classification: B66B13
IPC codes: B66B13, H01H1, H01H3