Abstract:
A monorail switching system for guided vehicles includes a main guideway mounted below the transportation monorail that engages a vertically shiftable keel assembly carried by the vehicle. For entrance/exit junctions, a secondary guideway defines the junction path is selectively engaged by lowering the shiftable keel from control by the main guideway. The plural guideways permit vehicles to travel in concert notwithstanding selective revision at the junctions.

Description:
FIELD OF THE INVENTION 
     The present invention relates to track systems for vehicles and, in particular, a switching system for individually and selectively routing vehicles between a main track and merged tracks on a dedicated route. 
     BACKGROUND OF THE INVENTION 
     Dedicated railed routing systems have been proposed for coordinating travel of vehicles along tracked paths. Frequently proposed systems include monorails, fixed rails, magnetic levitation systems and the like wherein all vehicles travel in synchrony along a main transit path and are merged thereto and therefrom for mass or individual entry or egress. One of the significant problems encountered in such approaches in maintaining traffic flow under merging conditions. Inasmuch as it is beneficial to maintain the traveling vehicles in close array for optimum traffic density and speed, safe and efficient entry and exit is of prime importance. Heretofore, it has been necessary to alter traffic flow on the main path to permit the discrete vehicle to enter or leave. This has required slowing traffic speeds at such points and providing sufficient vehicle spacing to permit the safe routing of the intended vehicle without inadvertently effecting proximate vehicles. Moreover during such traffic handling it is important that the routed vehicle remain stable under affirmative steering control. 
     For example, U.S. Pat. No. 889,441 to Christopher discloses a railway switch wherein a tracked vehicle selectively engages a ramp in advance of a turn off to shift mechanically track tongues to a position prescribing a divergent path. Such mechanical mechanism is slow acting and must be mechanically returned to the original position to avoid inadvertently affecting following traffic. 
     U.S. Pat. No. 3,363,584 to Brush et al. discloses a vehicle control system wherein one side of the vehicle is controlled by a rail system for main traffic routing and the opposed side of the vehicle is controlled by a second rail system to route the vehicle for egress and entry. Control requires alternative selective shifting for engaging the desired path and disengaging the prior path. 
     U.S. Pat. No. 3,451,351 to Hawes discloses a monorail switching system wherein laterally spaced guide rollers are selectively deployed to transfer steering and routing control between a main path and a transfer path. A similar system is disclosed in U.S. Pat. No. 3,593,668 to Adams wherein selectively lowered guide wheels are switched prior to a junction between a main channel and a transfer channel for electively steering a tracked vehicle at a transfer point. 
     U.S. Pat. No. 3,595,173 to Giraud discloses a roof plate on a vehicle that is raised to selectively engage a merging ramp for vertically routing a vehicle at a transfer junction. 
     U.S. Pat. No. 3,628,462 to hit discloses a vehicle switching apparatus wherein pivoting rollers on the vehicle are alternatively deployed for switching between a main path and a transfer path. 
     U.S. Pat. No. 3,640,227 to Webb discloses a suspended rail car system wherein swinging support rollers are selectively deployed between a main path and a divergent path for controlling the course of the car. 
     U.S. Pat. No. 3,838,648 to Dahlberg et al. discloses a transportation system wherein the vehicle selectively traverses ramped surfaces a divergent transfer points. 
     U.S. Pat. No. 4,092,931 to Wulf et al. discloses a guide mechanism for vehicles wherein steering control on a fixed path is provided by longitudinally spaced guide wheels engage a guide channel for controlled routing of the vehicle. 
     U.S. Pat. No. 5,016,542 to Mitchell discloses a transit system wherein hydraulically operated vanes are selectively deployed for routing a vehicle between a main line and a station. 
     The foregoing, while providing merging capabilities, require excessive vehicle separation in operation. Additionally, the systems do not provide for affirmative directional control of the vehicle during such maneuvers. Further, many of the systems do not readily adapt to incorporation with passenger vehicles in high speed applications requiring stable steering control during merging conditions. 
     In view of the above limitations, it is an object of the present invention to provide a switching system for tracked vehicles that is selectively deployed for entering tracked transit and for accessing merging conditions. 
     Another object of the invention is to provide a steering system for transit vehicles that retain affirmative tracking control during non-linear movement. 
     A further object of the invention is to provide a keel assembly for a transit vehicle that is selectively engagable with a track system for steering the vehicle during travel and merger conditions with minimum spacing between vehicles. 
     Yet another object of the invention is to provide a tracking system for vehicles that is selectively engaged by a steering keel deployed from the vehicle for affirmatively prescribing travel and merger operation. 
     SUMMARY OF THE INVENTION 
     The foregoing objects are accomplished by a monorail switching system for guided vehicles having a main guideway mounted below the transportation monorail that is selectively engaged a vertically shiftable elongated keel assembly deployed by the vehicle. For entrance/exit junctions, a secondary guideway below the main guideways defines the junction path and may be selectively engaged by lowering the keel assembly at a joint transition zone prior to the transfer route. The plural guideways permit vehicles to travel in concert notwithstanding selective revision at the junctions. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages of the present invention will become apparent upon reading the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is plan view of a transit switching system in accordance with an embodiment of the invention showing a guided vehicle at a departure transfer junction; 
     FIG. 2 is a side elevational view of the transit switching system shown in FIG. 1; 
     FIG. 3 is a plan view of the transit switching system showing a guided vehicle at an entry transfer junction; 
     FIG. 4 is a side elevational view of the vehicle at the merger transfer junction of FIG. 3; 
     FIG. 5 is an enlarged side elevational view of the vehicle of FIG. 1 at the departure transfer junction; 
     FIG. 6 is a schematic view illustrating the disposition of the keel with respect to the guideways at a merger transfer junction; 
     FIG. 7 is a perspective view of the keel assembly for the guided vehicle; 
     FIG. 8 is a side elevational view of the keel assembly in the main transit position prior to a departure transfer junction; 
     FIG. 9 is an exploded perspective view of the keel assembly and guideway; 
     FIG. 10 is a schematic view of the keel assembly in the main transit position; 
     FIG. 11 is a schematic view of the guided vehicle on the transit system; 
     FIG. 12 is a schematic view of the keel assembly at the transition section; and 
     FIG. 13 is a schematic view of an embodiment of the keel assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings for the purpose of describing the preferred embodiment and not for limiting same, FIGS. 1 and 2 illustrate a transit system  10  for routing vehicles  12  along a prescribed track switching system  14  under the control of a keel guide system  16 . The transit system  10 , as will hereinafter become apparent, may handle passenger or commercial vehicles along conventional surfaces or adapted vehicles along fixed guide paths, such a well known monorail-type system of either supported or suspended architecture. Further, the propulsion for such vehicles may be conventional power plants, linear magnetic levitation systems, or the like. The transit system will be described and illustrated with respect to a magnetic levitation system. 
     In such systems, the track system  14  prescribes forwardly directed main sections  20  for transiting vehicles, singularly or in concert with other vehicles, between spaced locations, and transition sections  22  for prescribing entry to or departure from the main sections  20  preparatory to a transfer junction  24 . During such movement along the track system, the vehicles may be individually controlled or alternatively and preferably cojointly controlled by a centralized system. 
     The main section  20  comprises a main upper guide way  30  supported at spaced locations along the length thereof. The transition section  22  as shown in FIG. 12 comprises a secondary lower guide way  32  supported vertically below the upper guide way  30 . The transition section  22  forms a plural guideway intermediate the main upper guideway  30  and the lower guideway  32  enabling the vehicle  12  to selectively route therebetween. The transition thus comprises an upper guide path forming a continuation of the upper guideway  30  and a lower guide path forming a continuation of the lower guideway  32 . The upper guide path and the lower guide path in the transition section communicate at transition slot  40 . As shown in FIGS. 3 and  4 , the track system in mirror image provides plural guide paths for accommodating merger of vehicles  13  from right to left, as illustrated, at entry sections  42  for merger with vehicles traveling along the main section  20 . 
     Referring to FIGS. 2 and 5, the vehicle  12  is provided with a retractable keel system  50  that may be selectively vertically positioned between an upper neutral position  52  above the traveling surface with the wheels  51  in a lowered for conventional propulsion, a first lowered position  54  coacting with the upper guideway  30  for controlling the vehicle with respect to the surface on the main roadway, and a second lowered position  56  coacting with the lower guideway  32  in the transition section  22  and the transfer section  24 , the wheels being in the illustrated raised positions. 
     The keel system  50  is supported by front and read guides  60  as positioned by actuator  62  or crank  63  under the control of the vehicle driver or a computerized control system. The keel system  50  is downwardly biased by spring  64 . The keel system  50  comprises an elongate bullet-shaped keel  66  laterally attached to a support plate  68  by pins  70  and slidably supported by the guides  60 . In the lowered positions  54 ,  56  the keel  66  is slidably conformably supported by the guideways  30 ,  32 , respectively. 
     As illustrated, the keel  66  has a substantially cylindrical shape bounded by the guideways  30 . The guideways have a generally C-shaped cross section including an arcuate shell  70  and a lateral longitudinal slot  72  through which the pins  73  project for connection with the support plate  68 . The keel  66  has an extended length slightly less than the wheelbase of the vehicle. The keel  66  may be mechanically, magnetically, roller supported or otherwise slidably constrained by the guides. Accordingly, the curvatures of the guideways will impart a steering force to the keel  66  and thereby to the vehicle whereby the latter will be properly oriented in the traffic lanes. 
     During main portions of the main section  20 , only the main guideway  30  is required. At the transition section as shown in FIG. 12, the guideway  80  comprises dual guiding shapes for the keel in both operative positions and during movement therebetween. This is effected by utilizing the top and bottom walls of the upper and lower guideways respective with a generally planar interconnecting wall  82 . During vehicle travel at the transition section, the operator may deploy the keel  66  between the positions and during such movement the interconnecting wall  82  will impart the steering control. 
     Adjacent the transfer section, the full contour of the lower guideway  32  is established for placing the vehicle under control of the interaction between the keel  66  and the lower guideway  32 . Thus, as the lower guideway diverges from the main guideway, affirmative control of vehicle movement is prescribed by the lower guideway path. In these zones, additional steering constraint may be provided by supplemental guiding contact with the reverse side of the support plate or by symmetrical use of a secondary keel assembly  86  as shown in FIG. 13, to the extent that such additional lateral constraint is desirable or necessary. 
     In order to further improve tracking, the transit system is provided with a conical alignment tip  90  on the leading end of the keel  60 . As shown in FIG. 8, the tip  90  may coact with a wedge shaped frog  92  located intermediate the upper guideway and the lower guideway at the intersection of the transition section and the transfer section. In this manner, if there is a slight misalignment in the selected position, the tip will center the keel  66  in the appropriate guideway. Further as shown in FIG. 6, the alignment tip  90  may engage a transition ramp  94  at a merging junction for establishing registration with the desired guideway. The alignment tip  90  is generally conical or otherwise tapered to provide a minimal frontal projection. The facing edges  96  of the frog  92  are similarly rearwardly outwardly flared. Accordingly, in the event the keel  66  is not completely aligned with the desired continuation path in the lower guideway, the surfaces of the alignment tip and the facing edges  96  of the frog  92  coact to bias vertically the keel  66  into the fully aligned condition. Further, as shown in FIG. 1, the trailing surfaces  98  of the frog interact with the keel  66  and support plate to provide affirmative routing along the intended course. 
     At the termination of the transfer section, sufficient length is provided for deceleration of the vehicle at a station or transfer point, or redeployment of the wheels to permit conventional travel on regular road surfaces. 
     The tracking system of the present invention has been described with reference to magnetic levitation/propulsion systems. Such as system will permit the transiting vehicles to travel at high velocities, alone or in tandem, and to interrelate travel with a central control system. However, it will be appreciated that the tracking system may be employed with other power systems and with modified conventional vehicles. Further it will be appreciated that the tracking system may also be employed for suspended propulsion systems. 
     The present invention thus provides a routing system for enabling vehicles to travel dedicated, limited access routes in close proximity to other vehicles, while permitting safe individual ingress and egress without disruption of through traffic, or inadvertent switching of leading or trailing vehicles. The system is amenable to various propulsion systems as well as conventional modes. Moreover, various supplement control systems may be utilized for coordination with all vehicles traveling thereover. 
     Having thus described a presently preferred embodiment of the present invention, it will now be appreciated that the objects of the invention have been fully achieved, and it will be understood by those skilled in the art that many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the sprit and scope of the present invention. The disclosures and description herein are intended to be illustrative and are not in any sense limiting of the invention, which is defined solely in accordance with the following claims.