Patent Publication Number: US-6662501-B2

Title: Emergency release mechanism for electrical bus door

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application is related to and claims benefit from U.S. Provisional Application Serial No. 60/289,319 filed May 7, 2001. This application is also closely related to U.S. application Ser No. 10/136,164, entitled “Electric Door Operator”, filed May 1, 2002. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to power operators for multi-passenger mass transit vehicles, more particularly to an emergency release mechanism for an electrically driven rotary door operator for opening and closing dual leaf swing doors such as used in multiple passenger vehicles including airport utility transports, school, and small transit buses. 
     BACKGROUND OF THE INVENTION 
     Prior to the use of power operated door openers, doors of mass transit vehicles were manually opened and closed, typically by the vehicle operator. The strain of actuating these door openings and closings often led to long term medical difficulties for the vehicle operators. The need for power operated door openers led to the development of largely pneumatically actuated operators since in most large vehicles, use of air brake systems provides a reliable and convenient source of operating air at controlled pressures. U.S. Pat. Nos. 4,490,941 and 4,134,231 show examples of pneumatic powered door operators. However, these types of vehicles typically incorporate hydraulic brake systems. Therefore, no air supply is available, and hydraulic door drives are high in cost and involve excessive maintenance in order to prevent leaks and loss of brake system integrity. A growing need for a reliable low cost electric bus door operator now exists. 
     A power door operator for multi-passenger mass transit vehicles in disclosed in U.S. Pat. No. 5,332,279, the specification of which is hereby incorporated by reference. This type of prior art system incorporates an electrically driven gear motor operating drive arms rotating approximately 160° in order to open and close a dual panel swing door set. A gear motor drive shaft operating through a sleeve clutch operates individually adjustable length drive arms of a drive bar in order to effect approximately 90° rotation of each door from open to closed and closed to open. The operating door shafts located at the outer edges of each panel have door arms affixed thereto for connection to the above-mentioned reciprocating drive arms through door drive rods. Each door drive rod end is interfaced between its respective drive arm and door arm with a spherical rod end. 
     In order to obtain door operation independent of the door power drive, or door operation in the event of operator failure or in an emergency situation, the clutch fork actuating bar  20  is manually actuated by an actuator assembly, see FIGS. 4-5 of U.S. Pat. No. 5,332,279 which are labeled as prior art FIGS. 1 and 2 of the present application. As shown in FIG. 2, the normal position of the mushroom headed plunger  34  is extended somewhat from the surface of the movable panel  31  internally into the vehicle. In the event that uncoupling of the operator and door panels is desired, it is only necessary to move the plunger end  35  toward the panel, thereby actuating the clutch fork actuating bar  20 , by compressing engaging spring  23  which allows the clutch fork assembly  16  to pivot on pins  17 , thereby moving the slide collar and drive bar assembly  8  inward along shaft  10  and disengaging the gear box drive shaft teeth  12  and aperture slots  14 . During clutch disengagement, drive rod ends  41  deflect inwardly, resulting in angular movement  43  of rods  40 . 
     With the clutch disengaged, resilient edges and vehicle body door seal mounted on the vehicle structure, having been compressed on closing, provide an initial door opening force. Therefore, on disengagement of clutch teeth  12  and slots  14 , the door panels are moved ajar. The doors can then be manually moved to an open position. When normal door operation is desired, it is only necessary to actuate the door motor. Re-engagement of the clutch teeth and apertures will again place the doors in their original relative positions for power operation. 
     A disadvantage of some types of prior art emergency releases which use toggle mechanisms as clamping devices require a large amount of travel of the clamping lever to achieve a very short stroke at the full load. A need exists for an emergency release mechanism which produces high final force within the mechanism resulting in relatively long travel of the lever under full load and a short travel of its driving arm. 
     The aforementioned related patent application, U.S. Ser. No. 10/136,164 is directed to an electric door operator for a mass transit vehicle. In the event of operator failure or in an emergency situation, there is a need for an emergency release mechanism which is compatible with this type of electric door operator. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an emergency release mechanism for use with a door operator of a multi-passenger mass transit vehicle for manually opening a door of this mass transit vehicle. The emergency release mechanism comprises a toggle mechanism having a first and second fixed pivot and a movable pivot positioned between this first and second fixed pivot. The first fixed pivot is secured to a wall portion of the vehicle. A target member is provided which is associated with and/or is a component of the door operator. This target member is capable of moving in a vertical direction to enable an emergency release of the door. A clamping lever is provided which has a first end and a second end. The first end of the clamping lever is pivotally attached to the second fixed pivot of the toggle mechanism and the second end of the clamping lever is capable of engaging the target member. A means is provided for mounting the clamping lever such that the clamping lever is capable of pivoting in a first and second direction to one of an engaging and disengaging position with respect to the target member. An actuating means is connected to the movable pivot of the toggle mechanism for pivoting the clamping lever in one of an engaging position and disengaging position with the target member for moving the target member in a vertical direction for achieving an emergency release of the door of the mass transit vehicle. 
     OBJECTS OF THE INVENTION 
     It is a primary object of the invention to provide an emergency release mechanism for use with a door operator of a multi-passenger mass transit vehicle. 
     It is a further object of the invention to provide an emergency release mechanism which is compatible for use with an electric rotary door operator. 
     It is another object of the invention to provide an emergency release mechanism which is compatible for use with safety release mechanisms. 
     It is yet another object of the invention to provide an emergency release mechanism which produces high final force within the mechanism resulting in relatively long travel of the lever under full load and a short travel of its driving arm. 
     It is still another object of the invention to provide an emergency release mechanism having a driving arm which is capable of traveling beyond a dead position while remaining in a released position. 
     In addition to the objects and advantages listed above, various other objects and advantages of the latch door operator disclosed herein will become more readily apparent to persons skilled in the relevant art from a reading of the detailed description section of this document. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial plan and tear-away top view of the gear motor, clutch, and drive arm ends with the clutch in a de-actuated state with the front panel in operating position, and doors in a release position allowing the doors to move freely according to a prior art design. 
     FIG. 2 is an additional partial tear-away view of the gear motor drive, clutch, and clutch fork actuator, with the operator front panel in position, particularly showing the clutch in an actuated position according to a prior art design. 
     FIGS. 3A and 3B are partial views of the release mechanism of the invention with the lever arm in a first and second position. 
     FIG. 4 is a side view of an electrical door operator including the release mechanism of the invention. 
     FIG. 5 is a top view of an electrical door operator. 
     FIG. 6 is a partial view of an electrical door operator. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document. 
     As illustrated in FIGS. 3A and 3B, the present invention is directed to an emergency release mechanism, generally indicated as  10 , for use with a door operator, generally indicated as  12 , of a multi-passenger mass transit vehicle for manually opening a door of this mass transit vehicle. 
     The emergency release mechanism  10  comprises a toggle mechanism, generally indicated as  14 , having a first fixed pivot  16  and a second fixed  18  pivot and a movable pivot  20  positioned between the first and second fixed pivots  16 ,  18 . The first fixed pivot  16  is secured to a wall portion  22  of the vehicle. A target member  24  is provided which is associated with and/or is a component of the door operator  12 . This target member  24  is capable of moving in a vertical direction to enable an emergency release of the door. A clamping lever  26  is provided which has a first end  28  and a second end  30 . The first end  28  of the clamping lever  26  is pivotally attached to the second fixed pivot  18  of the toggle mechanism  14  and the second end  30  of the clamping lever  26  is capable of engaging the target member  24 . 
     A means, such as a stanchion  32 , is provided for mounting the clamping lever  26  such that the clamping lever  26  is capable of pivoting in a first and second direction to one of an engaging and disengaging position with respect to the target member  24 . The stanchion  32  is positioned between the first end  28  and second end  30  of the clamping lever. 
     An actuating means  34  is connected at  35  to the movable pivot  20  of the toggle mechanism  14 . The actuating means  34  can be a drive arm or any well known means capable of pivoting the clamping lever  26 . The actuating means  34  is capable of pivoting the clamping lever  26  in one of an engaging position and disengaging position with the target member  24  for moving the target member  24  in a vertical direction for achieving an emergency release of the door of the mass transit vehicle. 
     The toggle mechanism  14  can include a biasing means  36  positioned between the movable pivot  20  and the second fixed pivot  18 . This biasing means  36  can comprise a spring or any other well known biasing means. 
     A return spring  38  is engaged with a predetermined portion of the clamping lever  26  to assist in disengaging the clamping lever from the target. 
     As shown in FIGS. 4-6, the emergency release mechanism can be used in combination with an electrically actuated rotary door  12 . In this embodiment, the driving arm  34  has an end portion  40  which is attached to the wall portion  22  of the transit vehicle at a fixed pivot point  42 . This fixed pivot point  42  corresponds with the first fixed pivot  16  of the toggle mechanism  14 . The driving arm  34  is capable of being manually actuated by rotation thereof about this fixed pivot point  42 . As stated above, the drive arm  34  is connected at 35 to the movable pivot  20  of the toggle mechanism  14  such that movement of the drive arm  34  results in the movement of the toggle mechanism  14  about the movable pivot  20 . Such movement of the toggle mechanism  14  results in pivotal movement of the clamping lever  26  in one of an engaging position and disengaging position with the target member  24  for moving the target member  24  in a vertical direction for achieving an emergency release of the door of the mass transit vehicle. 
     The target member  24  comprises a driving pinion  44  driven by a gear motor  45  within the electrically actuated rotary door operator  12 . The driving pinion  44  intermeshes with a gear sector  46  to achieve opening and closing of the vehicle door. Vertical movement of the driving pinion  44  results in disengagement of this driving pinion  44  from the gear sector  46  to enable manual opening of the vehicle door. 
     The driving arm  34  is also capable of traveling beyond a dead position or within a dead zone  48  while remaining in a released position. 
     The emergency release mechanism of the invention is especially convenient when target source yields high frictional drag. This high frictional drag can be produced between meshing teeth of the driving pinion  44  and the gear sector  46  during axial motion of the driving pinion  44  under full load during de-clutching a gear motor  45  from engagement with the driven gear sector  46 . 
     The toggle mechanism  14  having a pushing linkage absorbs energy during the initial stage of its motion via deflecting by the spring  36 . The stiffness of this spring  36  should be as high as demanded by the lever system serving a target member  24  and also deflecting the returning spring  38  acting in the opposite direction. The toggle mechanism also allows its driving arm to travel beyond the “dead” position in spite of the lever remaining in the released position. 
     The mechanism of the invention produces a high final force within a lever mechanism which provides a relatively long travel of the acting lever under full load and a short travel of its driving arm. Well known toggle mechanisms which are used as clamping devices provide large travel of the clamping lever and very short stroke at the full load. 
     The emergency release mechanism  10  of the invention produces high final force within the mechanism resulting in relatively long travel of the clamping lever  26  under full load and a short travel of its driving arm  34 . 
     The invention may be utilized in a variety of electrical rotary door operators and safety release mechanisms. Note that the clamping lever  26  may either engage or disengage the target member  24 , as shown in FIGS. 3A and 3B, to achieve vertical movement of this target member  24  to enable an emergency release depending upon the environment in which the emergency release mechanism is utilized. 
     It is noted that the Figures show the emergency release mechanism in combination with a door operator for opening and closing a pair of pivotally mounted swing doors. However, one having ordinary skill in the art would recognize that the emergency release mechanism may be utilized with a door operator for use with a single plug door. 
     The invention has been described in such full, clear, concise and exact terms so as to enable any person skilled in the art to which it pertains to make and use the same. It should be understood that variations, modifications, equivalents and substitutions for components of the specifically described embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims. Persons who possess such skill will also recognize that the foregoing description is merely illustrative and not intended to limit any of the ensuing claims to any particular narrow interpretation.