FRONT ENGINE REAR WHEEL DRIVEN LOW FLOOR NO STEP BUS

FIELD OF THE INVENTION

This invention relates to low floor type city buses such as buses having a step less entry at the entry doors. In particular, the invention relates to the drive train installation, the floor arrangement and the arrangement of engine and associated systems.

BACKGROUND OF THE INVENTION

With the increase in demand for public transportation, there has been an enormous focus in development of city buses. A lot of work is going on to make the city buses more commuters friendly. One prime feature that is sought after in a city bus is lower floor height. This is primarily required to enhance the comfort of passengers embarking and disembarking the vehicle. Over the years the floor heights of the city buses have evolved to provide an easy entrance to the vehicle. Conventional buses with 3 step entry typically have floor heights of 1150 mm, which later evolved to typically 900 mm with a two step entry, and recently to a single step entry with a typical floor height of 650 mm. Eventually, the city buses have ended up having a low floor or no step at all.

Buses with the above floor heights may be of both front engine type as well as rear engine type. However, the low floor or no step buses are predominantly of rear engine type (1). These rear engine type buses are comparatively more expensive due to the peripheral changes involved in the design. Although low floor buses of front engine configuration exist, but unlike the rear engine low floor bus which are rear wheel driven, these front engine buses are front wheel driven (2). It is to be noted that, to have better traction there should be sufficient load on the driven wheel. Further it is to be noted, the load on the front wheels are always lesser than those on the rear. Hence these buses have lesser traction and generally are not preferred. Schematics of the above mentioned low floor bus types are illustrated in FIG 1.

Another feature which is desired in a city bus is wider doors and more number of doors per bus. This is preferred in order to have faster passenger movement in and out of a bus. Hence it is required to have wider doors at front, middle and rear portion of the bus. In view of the above discussion it may be realized that there exists a need to have a low floor bus with a front engine installation and rear wheel driven (3] configuration, which is capable of having doors at the front, middle and rear portion of the bus.

OBJECT OF THE INVENTION

The main object of the present invention is to provide a low floor bus having a step less entry at the entry doors with a front engine installation and rear wheel driven configuration. Another object of the present invention is to provide a low floor bus having a step less entry at the entry doors with a front engine installation and rear wheel driven configuration, which simplifies the peripheral systems such as cooling system, air intake and so forth.Another object of the present invention is to provide a low floor bus having a step less entry at the entry doors with a front engine installation and rear wheel driven configuration, which reduces the cost significantly. Another object of the present invention is to install the drive train comprising the engine assembly, gear box assembly, propeller shafts and the rear axle assembly such that the gangway or the standee space inside the bus is in line with the step less entry.

SUMMARY OF THE INVENTION

In order to achieve the above mentioned objects, the present invention discloses a low floor bus including a flat floor throughout passenger saloon of the bus and having a step less entry for passengers, an engine assembly disposed in the front of the bus ahead of front axle, a gear box assembly installed with the engine assembly in line with the axis of the engine assembly, a front axle assembly holding front wheels, a driven rear axle assembly of portal type holding rear wheels configured to drive the low floor bus, a series of propeller shafts transferring power from the engine assembly to the rear axle assembly, wherein the engine assembly, the gear box assembly, the front axle assembly, the rear axle assembly and the series of propeller shafts in combination enables to achieve a flat floor throughout the bus and position entry doors at a low floor height.

In one embodiment, the engine assembly is positioned in the front of the bus ahead of the front axle assembly and is inclined at an angle to the horizontal plane of the ground so as to clear the angle of approach for the bus. In one embodiment, the engine assembly is offset from the centre line of the bus towards the driver side and is inclined at an angle to the centre line of the bus for providing sufficient gangway space for the passenger boarding at the front door. In one embodiment, the gear box assembly is coupled with the engine assembly and inclined along the engine assembly restricting the projection in the gangway. In one embodiment, the front axle assembly is configured either with a rigid double drop axle beam or with an independent front suspension for providing sufficient clearance for components above during axle travel. In one embodiment, the rear axle assembly is of portal type having the axle centre at a lower height and offset from the wheel centre having an additional reduction at the wheel ends making the crown wheel in the centre comparatively smaller. In one embodiment, the power from the gear box assembly in front is transmitted to the rear axle assembly in rear through a series of propeller shafts comprising a first propeller shaft, a second propeller shaft, a third propeller shaft and a fourth propeller shaft. In one embodiment, the first propeller shaft is coupled with the gear box assembly and is inclined at an angle to the horizontal plane of the ground and further inclined at an angle to the vehicle centre line wherein the installed angle allows the propeller shaft to be installed over the front axle assembly with adequate working clearance during the axle travel.

In one embodiment, the first propeller shaft is followed by the second propeller shaft and the third propeller shaft, which are installed parallel to the floor. In one embodiment, the fourth propeller shaft is installed at a predetermined angle to connect the third propeller shaft with the rear axle assembly, which is not aligned. Further, the fourth propeller shaft may be connected to the rear axle in flange arrangement or in yoke arrangement. In one embodiment, the first shaft is coupled with the gear box assembly which is placed in offset position and the series of propeller shafts are installed to one side of the vehicle causing no intrusion into the gangway space. In one embodiment, the floor construction is kept flat throughout the entire length of the bus at low floor level for providing step less entry to the passengers. In one embodiment, the floor is elevated on the side behind the driver till the rear axle to accommodate the series of propeller shafts. Further, the elevated portion of the floor may be utilized primarily to position passenger seats over it. It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and other advantages of the invention will be better understood and will become more apparent by referring to the exemplary embodiments of the invention, as illustrated in the accompanying drawings, wherein:

FIG. 1 shows schematic layouts of different types of low floor buses;

FIG. 2 shows an isometric view of the front engine rear wheel driven low floor bus according to one embodiment of the present invention;

FIG. 3 shows the top view of the bus with the seating and the floor arrangement;

FIG. 4 shows the drive train assembly from the top view;

FIG. 5 shows the drive train assembly with the floor from the top view;

FIG. 6 shows the drive train assembly installation with the floor from the side view;

FIG. 7 shows an isometric view of the entire drive train along with the double drop front axle assembly; and

FIG. 8 shows an isometric view of the drive train with the front axle assembly of independent suspension type according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein is the construction with which the subject invention is obtained. This invention is illustrated in the accompanying drawings, throughout which, like reference numerals indicate corresponding parts in the various figures. FIG. 2 illustrates the general arrangement of the bus with the engine assembly (4) positioned in the front ahead of the front axle assembly (5). For better passenger management and driver ticketing a wide door (6) is positioned ahead of the front axle (5). Doors (7] and (8) are also positioned in the wheelbase and in the rear overhang to further enhance passenger movement. FIG. 3 shows the top view of the bus with the seating and the floor arrangement as discussed above.

The engine assembly (4) is positioned in the front of the bus ahead of the front axle assembly and is inclined at a suitable angle to the horizontal plane of the ground (9) so as to clear the angle of approach (10) for the bus as illustrated in FIG. 6. Further the engine assembly (4) is offset from the centre line (11) of the vehicle more towards the diver (12) and is inclined at an angle to the centre line of the bus. The inclination is such that sufficient gangway space (13) or standee space is available for the passenger boarding at the front door (6). The same is illustrated in FIG. 4 and FIG. 5. The gearbox assembly (14) is coupled with the engine assembly (4) which falls in axis with the engine assembly and thereby remains further away from the centre line (11) of the vehicle ensuring sufficient gangway (13). The power from the engine is transmitted to the rear axle assembly (15) by a series of propeller shafts installed away from the centre line of the vehicle towards the driver side. In the present embodiment, there are four propeller shafts. However, the number of propeller may vary based on the length of the bus. A bus having shorter length may have less number of propeller shafts and similarly a long bus may include more number of propeller shafts as per requirement.

The first propeller shaft (16) is coupled with the gear box assembly (14) which is oriented along the same axis as that of the engine and the gear box. The angle is such that it allows the propeller shaft to be installed over the front axle assembly (5) with adequate working clearance even during the axle travel. The first propeller shaft (16) is followed by the second (17) and third (18) shaft which are installed parallel to the floor (20) and also parallel to centre line (11) of the vehicle. The last propeller shaft (19) connects the third propeller shaft assembly (18) with the rear axle assembly (15). The rear axle and the third propeller shaft not being inline, the last propeller shaft eventually gets installed at a predetermined angle. The last propeller shaft (fourth propeller shaft in the present embodiment) may be connected to the rear axle in flange arrangement or in yoke arrangement. The first shaft (16) being coupled with the gear box (14) which is offset, all the propeller shafts get installed to one side of the vehicle, thereby causing no intrusion into the gangway space.

The rear axle assembly (15) used in this invention is of portal type that has its axis offset and lowered from the axis of the wheels. Unlike the conventional axle, this rear axle assembly has a smaller crown wheel since it has an additional reduction at the hubs. This arrangement enables to have a low floor (20) in the rear portion of the bus as well. The rear floor yet has a smaller ramp ascending and descending over the rear axle to ensure sufficient clearance during axle travel. This ramp on the floor is maintained within the legal mandates. In a similar manner, the front axle assembly (5) used in this invention is of the double drop type as depicted in FIG 7, wherein the axle beam is lower than the conventionally used axle beams. This arrangement of axle beam facilitates a low floor over it. As an alternate arrangement depicted in FIG 8, instead of a beam type axle, an axle of independent suspensions type (21) is used. In either case, the front axle assembly provides sufficient clearance for components above it even during axle travel and also aids in achieving a low floor.

The floor (20) is built over the positioned aggregates ensuring adequate peripheral clearances, providing in addition step less entry and low floor standee space (22) for passengers. The floor is constructed such that it is elevated on the side behind the driver (12). This elevated space (23) houses the drive train components such as the engine, gear box and the propeller shaft. Since it is not at low floor level, the elevated space (23) is used to position the seats (24) for seated passengers. The floor opposite to driver or the entry side being devoid of the drive train is kept at low floor level. This low floor space (22) apart from providing a step less entry also provides standee space for passengers. The low floor side of the floor can also be utilized to accommodate the passenger on a wheelchair (25). Since the drive train ends with the rear axle assembly (15), the elevated portion truncates over the rear axle assembly and subsequently is placed at low floor level. It is to be understood by a person of ordinary skill in the art that various modifications and variations may be made without departing from the scope and spirit of the present invention. Therefore, it is intended that the present invention covers such modifications and variations provided they come within the ambit of the appended claims and their equivalents.

WE CLAIM:

1. A low floor bus comprising: a flat floor throughout passenger saloon of the bus and having a step less entry for passengers; an engine assembly disposed in the front of the bus ahead of front axle; a gear box assembly installed with the engine assembly in line with the axis of the engine assembly; a front axle assembly holding front wheels; a driven rear axle assembly of portal type holding rear wheels configured to drive the low floor bus; a series of propeller shafts transferring power from the engine assembly to the rear axle assembly; wherein the engine assembly, the gear box assembly, the front axle assembly, the rear axle assembly and the series of propeller shafts in combination enables to achieve a flat floor throughout the bus and position entry doors at a low floor height. The low floor bus as claimed in claim 1, wherein the engine assembly is positioned in the front of the bus ahead of the front axle assembly and is inclined at an angle to the horizontal plane of the ground so as to clear the angle of approach for the bus.

The low floor bus as claimed in claim 1, wherein the engine assembly is offset from the centre line of the bus towards driver side and is inclined at an angle to the centre line of the bus for providing sufficient gangway space for the passenger boarding at the front door. The low floor bus as claimed in claim 1, wherein the gear box assembly is coupled with the engine assembly and is inclined along the engine assembly restricting the projection in the gangway. The low floor bus as claimed in claim 1, wherein the front axle assembly is configured either with a rigid double drop axle beam or with an independent front suspension for providing sufficient clearance for components placed above during axle travel.

The low floor bus as claimed in claim 1, wherein the rear axle assembly is of portal type having the axle centre at a lower height and offset from the wheel centre having an additional reduction at the wheel ends making the crown wheel in the centre comparatively smaller. The low floor bus as claimed in claim 1, wherein the power from the gear box assembly in front is transmitted to the rear axle assembly in rear through a series of propeller shafts comprising a first propeller shaft, a second propeller shaft, a third propeller shaft and a fourth propeller shaft. The low floor bus as claimed in claim 7, wherein the first propeller shaft is coupled with the gear box assembly and is inclined at an angle to the horizontal plane of the ground and further inclined at an angle to the vehicle centre line wherein the installed angle allows the propeller shaft to be installed over the front axle assembly with adequate working clearance during the axle travel. The low floor bus as claimed in claim 7, wherein the first propeller shaft is followed by the second propeller shaft and the third propeller shaft, which are installed parallel to the floor.

The low floor bus as claimed in claim 7, wherein the fourth propeller shaft is installed at a predetermined angle to connect the third propeller shaft with the rear axle assembly which are not aligned. The low floor bus as claimed in claim 10, wherein the fourth propeller shaft is connected to the rear axle in one of flange arrangement or yoke arrangement. The low floor bus as claimed in claim 7, wherein the first shaft is coupled with the gear box assembly which is placed in offset position and the series of propeller shafts are installed to one side of the vehicle causing no intrusion into the gangway space. The low floor bus as claimed in claim 1, wherein the floor construction is kept flat throughout the entire length of the bus at low floor level for providing step less entry to the passengers. The low floor bus as claimed in claim 1, wherein the floor is elevated on the side behind the driver till the rear axle to accommodate the series of propeller shafts. The low floor bus as claimed in claim 14, wherein the elevated portion of the floor is utilized primarily to position passenger seats thereover.