Abstract:
Bus cabin structures including improved configurations of floors, passenger aisles and steps, interior roofs or ceilings, and door frames.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to floor and ceiling structures for transit buses and other vehicles. In particular, the invention relates to bus cabin structures having lower floors and upper floors, with transition floor modules therebetween, the transition modules having central aisles with recessed steps and angled front walls. 
       BACKGROUND OF THE ART 
       [0002]    The invention relates to cabin structures for vehicles, such cabins as used in wheelchair-accessible and other transit bus cabins. To allow access by passengers in wheelchairs, and disabled, elderly, or other passengers who have difficulty with stairs, including for example passengers with wheeled baby carriages or wheeled carrying devices, buses are commonly designed with a lower front floor section. 
         [0003]    Such floors may be made increasingly accessible when the bus stops by, for example, operating “kneeling” front suspension or lateral tipping suspension mechanisms to bring the floor adjacent the front and rear doors closer to the exterior curb elevation. Extendable ramps or lifts are also commonly used to enable wheeled access between external sidewalk surfaces and the lower, usually forward, floor of the bus cabin. 
         [0004]    Such bus cabin floors often have front wheel wells and/or other structures projecting significantly into the cabin, with a central aisle extending axially along the bus between the front wheel wells in buses with lower floors. The rear section of the bus usually includes an upper floor section beneath which the engine and other operating equipment is installed. A foot step can be used to transition between the lower and upper floor sections. The upper floor section is generally not accessible to wheelchairs or other wheeled devices. 
         [0005]    Due to the lower forward floor design, space for engine machinery, fuel tanks, and other bulky equipment within the bus is generally limited to beneath the rear upper floor. However, such available space may be inadequate for certain bus configurations. 
         [0006]    The transition step between the lower and upper floor sections is generally perpendicular to the central aisle extending axially through the bus cabin. Wheelchairs, baby carriages and other wheeled devices may collide or otherwise interfere with the step and become difficult to redirect laterally out the rear doors. Typically, wheelchair passengers and those with wheeled devices such as baby carriages prefer to exit through the front doors due to difficulty in navigating out the rear doors. This impedes entry of passengers through the front doors and generally slows down transit service as a result. 
         [0007]    Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below. 
       DISCLOSURE OF THE INVENTION 
       [0008]    In various aspects the invention provides a bus cabin structure comprising: a floor with an axially extending central aisle, the floor comprising: a lower floor section; and an upper floor section rearward of the lower floor section; a roof, a forward wall, a rear wall, curbside wall and driverside wall, each of the walls extending between the floor and the roof, the curbside wall including a rear door; wherein the floor includes a floor transition module rearwardly adjacent the rear door joining the lower floor section and the upper floor section together, a central aisle section of the module including a recessed foot step, the module having an upper surface aligned with the upper floor section and a base aligned with the lower floor section, the module having a front wall having a curbside portion rearward of a driverside portion and an aisle portion between the curbside and driverside portions disposed at a predetermined angle thereto. 
         [0009]    Among other advantages, the transition floor module provides increased space for bus equipment under the driverside portion which extends forwardly relative to the curbside portion. The angled aisle or step portion also increases the area of the step which improves the footing of passengers climbing or descending on steps in a moving vehicle, and also increases space for equipment underneath. The increased space provided beneath the transition module causes an equal reduction in space within the passenger cabin; however, since seats can be mounted on the upper driverside surface of the transition module, only under-seat space is reduced. This space is not normally utilized in transit buses. 
         [0010]    Further, the angled front wall of the transition floor section provides an angled bumper to more easily redirect wheeled devices laterally after colliding axially. The angled front wall wheeled redirects devices toward the rear doors and reduces the tendency for wheeled devices to become trapped in a right angle corner after collision with the step. The reduced difficulty in exiting through the rear doors, will encourage one-way flow of all passengers from front to rear and therefore will improve the overall efficiency of all passenger movements through the bus. 
         [0011]    In further aspects, the invention provides floors for transit buses and other vehicles, the forward portions of the lower floor sections forward of the front wheel wells including a front lateral aisle extending between a front door in the curbside wall and the central aisle, the front lateral aisle including a laterally downwardly sloping front ramp toward the front door. 
         [0012]    In further aspects, the invention provides floors for transit buses and other vehicles in which the forward floor portion includes a transversely extending raised portion between the front wheel wells having a top surface at a level above the lower floor section, a forward ramp, and a rearward ramp, the forward and rearward ramps extending between the raised portion and the forward portion and the rearward portion of the lower floor section respectively. 
         [0013]    In further aspects the invention provides cabin structures for transit buses and other vehicles, wherein the cabin roof upward of the upper floor section comprises a rear roof section having a central raised panel or other portion having an underside surface disposed at a higher level than an underside surface of a forward roof section. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0014]    In order that the invention may be readily understood, one embodiment of the invention is illustrated by way of example in the accompanying drawings. 
           [0015]      FIG. 1  is a longitudinal sectional view through a passenger bus showing the general layout of lower front floor, upper rear floor, ceiling panels, seats and stanchions mounted to the ceiling rail. 
           [0016]      FIG. 2  is an isometric schematic view from a top curbside position showing a partial bus chassis frame with a bus cabin structure having floor, roof, and partial vertical wall structures with rear and front door frames. 
           [0017]      FIG. 3  is an axial centerline sectional view through the bus cabin structure of  FIG. 2 . 
           [0018]      FIG. 4  is a floor plan view of the bus cabin structure shown in  FIG. 2 . 
           [0019]      FIG. 5  is an isometric detail view from showing details of the transitional floor module of  FIG. 2 . 
           [0020]      FIG. 6  is partial sectional view along line  6 - 6  of  FIG. 1 , showing the rear roof section. 
           [0021]      FIG. 7  is a partial perspective elevation view of the rear roof section along line  7 - 7  of  FIG. 1 . 
           [0022]      FIG. 8  is a sectional view along line  8 - 8  of  FIG. 1 . 
           [0023]      FIG. 9  is an isometric detail view of the upper-rear front door frame corner of  FIG. 2 . 
       
    
    
       [0024]    Further details of the invention and its advantages will be apparent from the detailed description included below. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0025]      FIG. 1  shows a longitudinal sectional view of a passenger bus to illustrate the layout of the interior passenger cabin, many parts of which are commonly used and known to those skilled in the art, so only a brief description is necessary. The bus is made wheel chair accessible by having a lower front floor  11  and lower thresholds for passenger exit and entrance doors (see door locations  7 ,  8  in  FIG. 2 ), with optionally axle suspension that may be actuated up and down to kneel or tilt as close as possible to the road or curb level, such as 14 inches or less. The front wheel wells protrude into the cabin and a central aisle permits passage from the front door towards the rear door. The rear portion of the floor  10  is raised to accommodate the rear axle, transmission and house other equipment. The rear portion of the floor  10  is accessible via one or more steps  14  and so is not wheel chair accessible. Seats  44  are supported with vertical stanchions  43  mounted to a longitudinal rail  42  and/or a side wall of the bus. 
         [0026]      FIG. 2  shows a partial bus chassis defining a bus cabin structure. Such cabins and chassis may be fabricated using any materials and processes suitable for accomplishing the purposes described herein. For example, the chassis frame may be fabricated of elongate roll-formed structural steel and/or extruded aluminium sections welded together to form the chassis base, roof and wall frames as outlined in  FIG. 2 . Flat roof, wall and floor panels of sheet metal or other materials are attached to the chassis frame to enclose the cabin and define the floor  1 , roof  2 , and vertical walls (front, rear, curbside and driverside walls  3 ,  4 ,  5 , and  6 ) with rear and front door frames  7 ,  8 . Other suitable materials can include fiber-based composite structures and structural plastics may also be used. 
         [0027]    The bus cabin structure includes a floor  1  with an axially extending central aisle  9 , the floor comprising: a lower floor section; and an upper floor section  10  rearward of the lower floor section  11 . The cabin is bounded by the roof  2 , a forward wall  3 , a rear wall  4 , curbside wall  5  and driverside wall  6 , each of the walls extending between the floor  1  and the roof  2 . The curbside wall  5  includes a rear door frame  7  within which a rear door may be mounted. 
         [0028]    As shown in  FIGS. 3-5 , the floor  1  includes a floor transition module  12  rearwardly adjacent the rear door frame  7  joining the lower floor section  11  and the upper floor section  10  together. A central aisle section  13  of the module  12  includes a recessed foot step  14 . The module  12  has an upper surface  15  aligned with the upper floor section  10  and a base  16  aligned with the lower floor section  11 . 
         [0029]    The module  12  has a front wall  17  having a curbside portion  16  rearward of a driverside portion  18  and an aisle portion  19  between the curbside portion  16  and driverside portion  18  disposed at an angle “A” thereto (see  FIG. 4 ). The angle A may be in the range of, for example, 30 to 60 degrees and as illustrated 45 degrees may be selected. 
         [0030]    The base  20  as illustrated comprises a forwardly-extending flange and the driverside portion  18  of the front wall  17  and the upper surface  21  of the floor transition module  12  define an upper seat mounting surface. 
         [0031]    The curbside portion  16  of the front wall  17  of the floor transition module  12  may be rearwardly adjacent the rear door frame  7 . The floor transition module  12  can be molded of fiberglass or carbon fiber as a hollow molded shell, or fabricated in any other way compatible with the purposes disclosed herein. 
         [0032]    A rear lateral aisle  22  extending between the rear door frame  7  and the central aisle  9  can include a laterally downwardly sloping rear ramp  23  toward the rear door frame  7 . 
         [0033]    In the embodiment shown, lower floor section  11  includes laterally spaced-apart front wheel wells  24  with the axially extending central aisle  9  therebetween. The lower floor section  9  has a forward portion  25  forward of the front wheel wells  24  and a rearward portion  26  rearward of the front wheel wells  24 . The upper floor section  10  includes laterally spaced apart rear wheel wells  27  with the central aisle  9  extending therebetween. 
         [0034]    In the illustrated embodiment the lower floor section  11  includes a transversely extending raised portion  28  between the front wheel wells  2  having a top surface at a level above the lower floor section  11 . A forward ramp  29  and a rearward ramp  30  extending between the raised portion  28  and the forward portion  25  and the rearward portion  26  of the lower floor section  11  respectively. 
         [0035]    The forward portion  25  of the lower floor section  11  forward of the front wheel wells  24  includes a front lateral aisle  31  extending between a front door frame  8  in the curbside wall  5  and the central aisle  9 . The front lateral aisle  31  includes a laterally downwardly sloping front ramp  32  toward the front door frame  8 . 
         [0036]    As will be appreciated by those skilled in the relevant arts, the use of sloping floor portions  29 ,  30 ,  32 ,  23 , etc., can provide advantages such as lower thresholds for forward and rear doors  8 ,  10 , by for example accommodating a front axle (not shown) supporting wheels disposed in wheel wells  24  and other apparatus beneath the floor sections of the cabin structure. The inventors have found that providing floor portions  29 ,  30 , etc., at angles of between about 1 degree and 5 degrees, and preferably about 2 degrees, relative to main portions of the floor  11  provides desirable combinations of floor configuration and door thresholds in currently-common bus constructions. In particular, the sloping of such floor portions at such rates has been found to provide significantly improved door threshold heights without interfering with passenger movement within the bus. 
         [0037]    The roof  2  upward of the upper floor section  10  can comprise a rear roof or ceiling section  33  including a central raised panel  34  having an underside surface disposed at a higher level than an underside surface of a forward roof section  35 . The rear roof or ceiling section  33  can include an upwardly-rearwardly-sloped transition panel  36  between the central raised panel  34  and the forward roof section  35 . The central raised panel  34  can includes a ventilation opening and/or emergency hatch  37 . The roof or ceiling structure can include a pair of continuous longitudinal rails  42  spanning the forward roof section  35  and laterally bounding the central raised panel  34  and the transition panel  36 . As will be understood by those skilled in the relevant arts, once they have been made familiar with this disclosure, by, for example, configuring the longitudinal rails  42  in a such that they are substantially horizontal and/or parallel to one or more of floor section(s)  10  and/or  11 , as shown for example in  FIG. 1 , while providing transition panel  36  raised panel  34  above, for example, a central aisle provided between seats for passenger ingress and egress, various combinations of passenger convenience, structural strength, and pleasing aesthetic arrangements may be attained. The stanchions  43  can be positioned at any longitudinal location to the rails  42 . 
         [0038]    As shown in  FIGS. 2 and 9 , the curbside wall includes front and rear door frames  7 - 8 .  FIG. 9  shows the details of a top-rear corner of the front door frame  8  which is typical of the door frame construction, with a fore and aft pair of vertical door posts  40 , and a horizontal door header  38  with rounded top corners merging the header  38  and door posts  40  in a continuously formed inverted U-shape. The pair of vertical door posts  40 , and a horizontal door header  38  comprise a square tubular steel structural section, formed by cold rolling or bending, for example. Other vertical posts  39  and horizontal members  45  are welded to the door frame  8  to fabricate the curbside wall portion of the chassis frame. The right angle joints between the vertical posts  39  and the horizontal members  45  are welded and can be reinforced with a corner bracket  41  to reduce stress concentrations and the resultant metal fatigue. However the continuous rounded and formed top corners of the door frame  8  merging the door posts  40  and header  38  have been found to be structurally superior to a conventional right angle welded corner even though more effort is required. The door frame openings are substantial in size and bending stresses, induced by bus movements and collisions, tend to be concentrated at the top corners of the door frames  7 ,  8 . 
         [0039]    Although the above description relates to a specific preferred embodiment as presently contemplated by the inventor, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.