A REAR ENGINE BUS HAVING SEMI LOW FLOOR OR LOW FLOOR ENTRY FOR PASSENGERS

FIELD OF THE INVENTION

The invention relates to a rear engine bus having semi low floor or low floor entry for passengers. In particular, the invention relates to frame construction, the floor arrangement and the arrangement of engine and the systems associated with the engine.
BACKGROUND OF THE INVENTION

With the increase in patronage for public transportation, there has been an enormous focus in development of city buses. A lot of work is carried on to make the city buses more commuters friendly. One prime feature of a city bus that is sought after is lower floor height. This is done essentially to enhance the comfort of passengers embarking and disembarking the vehicle. Over the years, the city buses have evolved from being a high floor bus to a low floor bus. A drastic step in this evolution was the introduction of rear engine buses. There is a restriction in lowering the floor height beyond certain limit due to the presence of engine in the front, hence the engine was moved to the rear allowing the floor height to be reduced further. Fig. 1 and Fig. 2 show the schematic layouts of rear engine buses of semi low floor type and low floor type.

Shifting the engine to the rear though aids in lowering the floor height at the front, however the rear potion still remains at an elevation 1 due to the presence of rear axle, engine and its peripheral systems beneath it. Passengers require lesser effort whilst boarding such a bus but still experience discomfort while moving rearwards essentially due to the elevation. The passengers have to climb two or more steps 2 to get seated on to an elevation 1. Another feature of a city bus which is looked upon is wider doors and more doors per bus. This is preferred to have faster passenger movement in and out of a bus. Hence it is ideal to have wider doors at front 3, middle 4 and rear 5 portion of the bus. With a bus having engine at rear, provision for a wider door on the front and the middle is not a concern. But providing a wider door on the rear becomes unviable because of the presence of rear axle, engine and its peripheral systems beneath it. Therefore, in light of above problems, there is a need to develop an improved construction of the bus which has lower floor height even at the rear elevation and support the provision of a wider door on the rear.

SUMMARY OF THE INVENTION

In order to solve the above-described problem, the main object of the present invention is to provide a rear engine bus having semi low floor with single step entry for passengers comprising a flat floor throughout passenger saloon of the bus. In order to solve the above-described problem, another object of the present invention is to provide a rear engine bus having low floor wherein the front door and middle door are step less entry doors for passengers and the rear door is single step entry door for passengers. Another object of the present invention is to provide a rear engine bus having low floor or semi low floor with a door on the rear potion of the bus which is as wide as the doors provided on the front and middle portion of the bus. Yet another object of the invention is to develop a rear engine bus having low floor or semi low floor with a frame assembly that aids in installation of the engine in the intended position so as to have no or minimal elevation on the rear floor. Furthermore, the frame assembly that aids in installation of engine in an angle so as to restrict elevation on the rear floor. Additionally the frame has adequate clearances over the axles to provide sufficient clearance during axle travel.

Further object of the invention is to develop a floor arrangement which is flat throughout the entire length of the bus. The floor is constructed in such a way as to accommodate the wheels and the corresponding clearances for them during wheel travel, also accommodate seats in an optimized manner such that the seating is maximum but still comfortable to the passenger and having comfortable gangway and of adequate strength to bear the load from seated and standee passengers. In order to have a flat floor in the present invention, the conventional rear axle is not used. The conventionally used rear axle has a single reduction and hence a larger crown wheel casing, this hinders in achieving a fiat floor over the axle. Hence the rear axle used in this invention is of the double reduction or hub reduction type in which reduction occurs in two stages, one on the crown wheel and the other at the hub there by having a smaller crown wheel casing which can be accommodated under a low floor.

Accordingly, the present invention provides a rear engine bus having semi low floor with single step entry for passengers, comprising: a flat floor throughout passenger saloon of the bus with a single step entry of passengers; a front door, a middle door and a rear door with same configuration for entry of passengers; a frame assembly with two longitudinal rails placed parallel and profiled over rear axle to provide clearance for axle travel and profiled to suit the engine position; a rear axle houses a smaller crown wheel casing and configured to drive the low floor bus; an engine assembly positioned on the rear of the bus between the parallel rails of the frame assembly; a gear box assembly along with the engine assembly inclined with the horizontal plane by a predefined angle; wherein the engine assembly, the gear box assembly and the rear axle assembly in combination with the frame assembly enables to achieve a flat floor at lower height and a rear door with single step entry with same configuration like the front door and middle door behind the rear axle.

In one embodiment, the front door is ahead of the front axle, the middle door is between the front axle and the rear axle, and the rear door is after the rear axle of the bus. In one embodiment, the engine assembly positioned on the rear of the bus is inclined at an angle with the horizontal plane of the floor and/or the engine rotates about its axis to the side which is opposite to the rear door. In one embodiment, the gear box assembly coupled with the engine assembly and hence inclined along the engine assembly and thereby restricting the projection of the gear box beyond the horizontal plane of the floor. In one embodiment, power from the engine and the gear box assembly is transferred to the rear axle assembly by a propeller shaft and the rear axle comprises a hub reduction type rear axle. In one embodiment, the frame assembly is made of two parallel placed rails which are connected by a succession of cross members between them and mounted with outriggers in succession on the exterior side mostly in line with the cross members and the frame rails are profiled at the portion over the rear axle to provide sufficient clearance for axle travel and profiled at the portion where the engine is positioned to suit the engine assembly installation.

In one embodiment, the floor construction is such that it is kept flat throughout the entire saloon except over the wheels to accommodate wheel travel and the floor is raised slightly at the portion which is over the engine assembly in accordance with the engine assembly installation. In one embodiment, the rear door behind the rear axle is made narrow, thereby accommodate additional seats in the space gained and still supporting a single step entry through the rear door. In one embodiment, the engine assembly is installed at a position which is attained by rotating the engine about its axis to the side which is opposite to the rear door. In one embodiment, an additional axle is introduced behind the existing rear axle for a longer version of the bus. Accordingly, the present invention also provides a rear engine bus having low floor entry for passengers, comprising: a flat floor having a front door with step less entry, middle door with step less entry and rear door with single step entry for passengers; a front door, a middle door and a rear door with same configuration for entry of passengers; a frame assembly with two longitudinal rails placed parallel and profiled over rear axle to provide clearance for axle travel and profiled to suit the engine position; a rear axle houses a smaller crown wheel casing and configured to drive the low floor bus; an engine assembly positioned on the rear of the bus between the parallel rails of the frame assembly; a gear box assembly along with the engine assembly inclined with the horizontal plane by a predefined angle; wherein the engine assembly, the gear box assembly and the rear axle assembly in combination with the frame assembly enables to achieve a flat floor at lower height and a rear door with single step entry with same configuration like the front door and middle door behind the rear axle.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The advantages and features of the invention will become more clearly apparent from the following description which refers to the accompanying drawings which constitute part of this complete specification are given as non-restrictive examples only and in which:

Figure 1 shows a schematic of a single step rear engine semi low floor bus in accordance with the prior art;

Figure 2 shows a schematic of a low floor bus in accordance with the prior art;

Figure 3 illustrates a schematic of a single step rear engine semi low floor bus in accordance with the present invention, which has a flat floor throughout;

Figure 4 demonstrates a schematic of a step less rear engine low floor bus in accordance with the present invention;

Figure 5 shows the profile of the longitudinal frame members which run across the length of the bus;

Figure 6 shows the floor arrangement on the rear portion of the bus;

Figure 7 shows the frame, seating and the door arrangement on a single step flat floor bus as per the present invention;

Figure 8 shows an isometric view of a single step rear engine flat floor bus depicting the floor, seating and door arrangement;

Figure 9 shows an isometric view of a low floor rear engine bus depicting the floor, seating and door arrangement;

Figure 10 shows the comparison of normal/vertical engine installation with an inclined engine installation and the corresponding impact on the floor height;

Figure 11 shows an isometric view of a longer version of single step rear engine flat floor bus depicting the floor, seating and door arrangement;

Figure 12 shows an isometric view of a longer version of low floor rear engine bus; depicting the floor, seating and door arrangement

Figure 13 shows an isometric view of frame for a semi low floor bus;

Figure 14 shows an isometric view of frame for a low floor bus;

Figure 15 shows the rear portion of the bus with the floor and seat arrangement; and

Figure 16 shows the rear portion of the chassis with the drive train arrangement

DETAILED DESCRIPTION OF THE PRFERRED EMBODIMENTS

In order to attain a flat floor throughout the entire length of the bus as depicted in Fig.3, the engine assembly 6 is positioned in the rear portion of the bus with its axis being inclined at an angle with the horizontal plane of the ground 7 as shown in Fig. 15. The engine assembly is installed at an angle to clear the departure angle 8 with the ground, yet ensuring that the engine assembly doesn't have greater amount of intrusion into the floor space 17. The gear box assembly 9 is coupled with the engine assembly 6 and hence takes the installation angle as that of the engine assembly. Being inclined along with the engine assembly the gear box assembly makes no projection beyond the horizontal plane which is in line with the floor.

Referring to Fig. 3, it semi low floor bus having a flat floor 17 running through the entire length of the bus except for elevations at wheel arches 19 over the wheels to provide sufficient clearance for axle travel. Similar to the semi low floor bus as illustrated in Fig 3, Fig 4 depicts the side view of a low floor bus having a flat floor 25 at low floor level. The front door 23 and the middle door 24 provide a step less entry for the passengers .Whilst the rear door 22 provides a single step entry for passengers entering ,accessible through a single step 18. As illustrated in Fig. 16, the rear axle assembly 10 is situated ahead of the gear box assembly 9. The power from the transmission i.e. the engine and the gear box assembly is transferred to the rear axle assembly by a propeller shaft 11. The rear axle used in this invention is of the hub reduction type i.e. having an additional reduction on the wheel ends apart from the reduction at the crown wheel in the centre. Hence this rear axle houses a smaller crown wheel casing in the middle there by a smaller axle dome whose height is far below the horizontal plane of the floor ensuring no intrusion of axle into floor 17 and also adequate gap to permit the axle to travel up without hitting the floor, during bump on road.

The engine assembly 6, gear box assembly 9 and the rear axle assembly 10 is mounted on to the frame assembly as in Fig. 13. The frame assembly is made of two parallel placed rails 12, each rail is constituted of a series of smaller rail portions which are joined in series as shown in Fig. 5. The two parallel placed frame rails 12 are connected by a succession of cross members 13 between them. The frame rails 12 are mounted with outriggers 14 in succession on the exterior side mostly in line with the cross members 13. The rails 12 are profiled at the portion 15 over the rear axle to provide sufficient clearance for axle travel and also profiled at the portion 16 where the engine is positioned to suit the engine assembly installation. Referring to Fig. 8, the floor 17 is mounted directly on top of the frame assembly. The floor is accessed by a passenger by climbing a single step 18. The floor construction is such that it is flat throughout the entire saloon except over the wheels so as to accommodate wheel travel during bumps as shown in Fig. 7. These portions which are claimed to be the wheel arches 19, house seats 20 on top of them but are not eligible to be considered as a standee floor area. The floor is elevated slightly in the rear portion 21 over the engine assembly as shown in Fig. 6.

As shown in Fig. 7, there is a rear door 22 behind the rear axle, similar in size to that of the door in the front portion of the bus 23 i.e., ahead of the front axle and similar in size to that of the door in the middle portion of the bus 24 i.e., between the front and the rear axle. The door 22 in the rear portion supports a single step 18 access to floor just like the front door and the middle door. Having achieved a rear door, alternatively a narrow door can be provided in the same place and thereby adding seats in the space gained. As a version of the engine installation shown in Fig. 10, the engine assembly 6 is installed at a position which is attained by rotating the engine about its axis to the side which is opposite to the rear door 22. The engine tilts to one side of the bus thereby the installed height of the engine assembly is minimum. Fig. 10 compares the versions of the installations and could be observed that when the engine is tilted the floor 17 is lower by an amount 'X". This arrangement makes the floor 17 devoid even of the slightly raised portion 21 in rear of the floor as mentioned earlier. As shown in Fig. 9, another embodiment of the invention is the low floor bus in which the passenger access the flat floor 25 by a step less entry through the front door 23 and the middle door 24.

The portion behind the middle door as shown in Fig. 6 is similar to the earlier embodiment of the invention i.e., the semi low floor bus. This low floor bus comprises of a rear portion which houses the same rear door 22 as on the rear of a semi low floor bus and is accessed by the passenger by a single step 18. Having the engine assembly, gearbox assembly and the rear axle assembly same as that of the semi low floor bus, the low floor version of the bus houses the same floor construction and the frame construction in the rear potion of the bus. As shown in Fig. 14, the frame for the low floor bus comprises of the rear portion i.e., behind the middle door similar to the earlier embodiment. Ahead of which the frame assembly though similar in construction is lower in height, so as to accommodate a step less entry. The frame in this portion is made of two parallel placed square tubes 26 which are interconnected by square tubes 27 of similar section. The parallel placed square tubes are mounted with outriggers 28 on the either side mostly in line with the interconnecting square tubes.

Yet another embodiment of the invention as shown in Fig. 11 and Fig. 12 is the longer version of the earlier mentioned semi low floor bus and the low floor bus. This remains similar in construction to the earlier mentioned embodiments expect the introduction of another axle 29 behind the initially installed rear axle assembly 10. Making the bus longer increases the passenger capacity and thereby increases the load on axles, the third axle is introduced to bear this additional load. Though the present invention was shown and described with reference to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

WE CLAIM:

1. A rear engine bus having semi low floor with single step entry for passengers, comprising: a flat floor throughout passenger saloon of the bus with a single step entry of passengers; a front door, a middle door and a rear door with same configuration for entry of passengers; a frame assembly with two longitudinal rails placed parallel and profiled over rear axle to provide clearance for axle travel and profiled to suit the engine position; a rear axle houses a smaller crown wheel casing and configured to drive the low floor bus; an engine assembly positioned on the rear of the bus between the parallel rails of the frame assembly; a gear box assembly along with the engine assembly inclined with the horizontal plane by a predefined angle; wherein the engine assembly, the gear box assembly and the rear axle assembly in combination with the frame assembly enables to achieve a flat floor at lower height and a rear door with single step entry with same configuration like the front door and middle door behind the rear axle.

2. The rear engine bus as claimed in claim 1, wherein the front door is ahead of the front axle, the middle door is between the front axle and the rear axle, and the rear door is after the rear axle of the bus.

3. The rear engine bus as claimed in claim 1 or 2, wherein the engine assembly positioned on the rear of the bus is inclined at an angle with the horizontal plane of the floor and/or the engine rotates about its axis to the side which is opposite to the rear door.

4. The rear engine bus as claimed in any one of claims 1 to 3, wherein the gear box assembly coupled with the engine assembly and hence inclined along the engine assembly and thereby restricting the projection of the gear box beyond the horizontal plane of the floor.

5. The rear engine bus as claimed in any one of claims 1 to 4, wherein power from the engine and the gear box assembly is transferred to the rear axle assembly by a propeller shaft and the rear axle is of hub reduction type.

6. The rear engine bus as claimed in any one of claims 1 to 5, wherein the frame assembly is made of two parallel placed rails which are connected by a succession of cross members between them and mounted with outriggers in succession on the exterior side mostly in line with the cross members and the frame rails are profiled at the portion over the rear axle to provide sufficient clearance for axle travel and profiled at the portion where the engine is positioned to suit the engine assembly installation.

7. The rear engine bus as claimed in any one of claims 1 to 6, wherein the floor construction is such that it is kept flat throughout the entire saloon except over the wheels to accommodate wheel travel and the floor is raised slightly at the portion which is over the engine assembly in accordance with the engine assembly installation.

8. The rear engine bus as claimed in any one of claims 1 to 7, wherein the rear door behind the rear axle is made narrow, thereby accommodate additional seats in the space gained and still supporting a single step entry through the rear door.

9. The rear engine bus as claimed in any one of claims 1 to 8, wherein the engine assembly is installed at a position which is attained by rotating the engine about its axis to the side which is opposite to the rear door.

10. The rear engine bus as claimed in any one of claims 1 to 9, wherein an additional axle is introduced behind the existing rear axle for a longer version of the bus.

11. A rear engine bus having low floor entry for passengers, comprising: a flat floor having a front door with step less entry, middle door with step less entry and rear door with single step entry for passengers; a front door, a middle door and a rear door with same configuration for entry of passengers; a frame assembly with two longitudinal rails placed parallel and profiled over rear axle to provide clearance for axle travel and profiled to suit the engine position; a rear axle houses a smaller crown wheel casing and configured to drive the low floor bus; an engine assembly positioned on the rear of the bus between the parallel rails of the frame assembly; a gear box assembly along with the engine assembly inclined with the horizontal plane by a predefined angle; wherein the engine assembly, the gear box assembly and the rear axle assembly in combination with the frame assembly enables to achieve a flat floor at lower height and a rear door with single step entry with same configuration like the front door and middle door behind the rear axle.