FRONT SUSPENSION UNIT FOR ONE STEP ENTRY (E+l) FRONT
ENGINE BUS

FIELD OF THE INVENTION

The present invention relates to a suspension unit for low floor vehicles. More specifically relates to the suspension unit for a front axle of a one step entry front engine passenger vehicle.

BACKGROUND OF THE INVENTION

A variety of vehicles are in use today. A number of configurations are available for various needs. One particular type of vehicle is low floor bus. Such vehicles are typically characterized by a passenger aisle that is relatively low to the ground so that the people entering or leaving the vehicle is easy and quick. Most of the standard buses have a floor height of about 1150mm, which is entry plus three steps (E+3). The entry plus two steps (E+2) have a typical floor height of about 890mm. Globally and in India, low floor buses with a floor height of at least 650mm or less are usually rear engine driven, and hence come with step seating on the rear side of the bus. These suites western countries with few passengers and good roads and where there are no conductors for ticketing. In India buses are overcrowded, with more standees, roads are bumpy and the bus conductor used to walk from the front to rear end of the vehicle a hundred times every shift. Also from operational standpoint, rear engine buses are considered more expensive to operate than front engine buses.

In current scenario, front engine buses have more than two stepped entry (E+2) which have a minimum step dimension of about 250mm each. It poses difficulty to senior citizens and disabled passengers for move in or move out of city buses. With this constraint, city buses take more time at bus stops for the ingress and egress of passengers, especially in peak traffic hours. All the low floor buses with floor height of at least 650 mm or less are with rear engines. The rear engine buses come with entry plus one step (E+l) platform as shown in the Fig 1, which reduces the ingress and egress time, but is substantially higher cost. Rear engine buses have steps in rear saloon area causing additional fatigue to conductor when moves to collect fare and give tickets. Maintenance cost of rear engine vehicles is higher when compared to front engine vehicle and further more cooling efficiency is achieved with front engine vehicles. While low floor buses serves as an important purpose, the necessary design constrains put limitations on other portions of the vehicle. One challenging aspect has been to design an appropriate suspension for the vehicle wheels. In the field of transport, the stability of the vehicle on uneven grounds is guaranteed by using suspension units which are applied to each wheel by connecting the wheel hub to vehicle frame, as it is widely known in the art.

Typical packaging space available for drive axle used on rear engine low floor buses do not permit the use of same suspension unit to front engine one step entry buses by meeting all other legal requirements and boundary conditions. Alternatively, the control components would be too restricted and the result would be too much camber variation and/or too much track variations at the vehicle wheels. The suspension unit for the one step entry front engine bus has to be designed separately in order to meet all legal requirements. In particular specific configuration of mentioned suspension unit needs some external space, in the wheel house ,suitable for housing each wheel and its respective bulky suspension unit, consequently reducing the space in the cabin of the vehicle over the front wheels, devoted to driving parts, namely pedals and steering wheels. The packaging of front door in front overhang of the vehicle in the available limited space is very cumbersome. Hence, there is a need to design a new front suspension unit for one step entry (E+l) front engine low floor buses by maintaining the uniform floor height from front to the rear of the vehicle and also meeting all the legal requirements of bus body code (AIS 052).

SUMMARY OF THE INVENTION

It is the feature of the present invention to realize a suspension unit for wheels, in particularly for front wheels of one step entry (E+l) front engine passenger vehicle, which is effective and compact, in order to make inside saloon area wider and comfortable. The principal object of the present invention is to realize a new front suspension unit for one step entry front engine low floor passenger vehicle, preferably bus, by maintaining a uniform floor in the bus saloon area i.e. from front of the vehicle to the rear of the vehicle. Further object of the present invention is to provide a sufficient space for packaging of different suspension components by meeting legal requirements of bus body code and also boundary conditions. Other object of the present invention is to provide a minimum gangway width of at least 450 mm after the one step entry for one step entry (E+l) front engine passenger bus. Another object of the present invention is the mounting of compound links or V links on the front axle without compromising on ground clearance. Yet another object of the present invention is to provide a new configuration for front suspension unit of one step entry front engine passenger bus such that placing of the front door is possible either behind the front axle or in front of the front axle.

Yet another object of the present invention is arrangement of air bellows in the minimum available space by maintaining the uniform floor height from front to rear of the vehicle. A front suspension unit for one step entry (E+l) low floor buses realized according to the present invention comprises a front axle suspended by plurality of air bellows arranged between the frame top and front wheels in lateral direction and between frame and front axle in vertical direction, at both the ends of said front axle; air bellow brackets covering each said air bellows; pluralities of shock absorbers being mounted between said front axle and an air spring bracket; pluralities of right and left rods called parallel links, one end of each parallel link is secured to a chassis frame pivotally and other ends of which are being secured on side sections of front axle, wherein said parallel links are being arranged in the longitudinal direction of said chassis frame; plurality of lower rods called compound links or v link, one end of each is being secured to said chassis and other ends are being secured pivotally to a position near the center section of said front axle so as to from V shape; and an anti roll bar, one end of which is being secured pivotally to said front axle in longitudinal direction and other is being secured to chassis. A preferred exemplary embodiment is explained in greater detail in the following description and illustrated in the drawings.

BRIEF DISCRIPTION 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 given as non-restrictive examples only and in which:

Fig.l shows the configuration of one step entry (E+l) buses with rear engine in accordance with the prior art.

Fig.2 shows a frame assembly for low floor front engine bus comprises frame side members, cross members and outriggers to support engine.

Fig 3 shows a perspective view front air suspension unit for one step entry (E+l) front engine bus in accordance with the present invention

Fig 4 shows the configuration of one step entry (E+l) bus with front engine, and with front door placed in front of the front axle in accordance with the present invention.

Fig 5 shows the configuration of one step entry (E+l) bus with front engine, and with front door placed behind the front axle in accordance with the present invention.

Fig 6 shows different disassembled components of front air suspension unit for one step entry (E+l) front engine bus in accordance with the present invention.

Fig 7 shows the front view of packed suspension components of one step entry (E+l) buses with front engine in accordance with the present invention.

DETAILED DISCRETION OF THE INVENTION

The present invention will be described herein below with reference to the accompanying drawings. The following description is of exemplary embodiment of the invention only, and is not limit the scope, applicability or configuration of the invention. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments of the invention. As will become apparent, various changes may be made in the function and arrangement of the structural features described in these embodiments without departing from the scope of the invention as set forth herein. It should be appreciated that the description herein may be adapted to be employed with alternatively configured devices having different shaped, components, and the like and still fall within the scope of the present invention. Thus the detailed description herein is presented for purposes of illustration only and not of limitation.

The front suspension unit for a one step entry (E+l) front engine passenger vehicle is described in the following description. The vehicle is referred herein and exemplified as a passenger bus in the figures; however, the vehicle may comprise any commercial or industrial vehicle. The different aspects described herein below with reference to accompanying drawings relates to realizing a front suspension unit for the one step entry (E+l) passenger bus with the engine mounted at the front of the vehicle by maintaining a uniform floor in the bus saloon area i.e. from front of the vehicle to the rear of the vehicle. A frame assembly of front engine low floor bus with E+l platform is shown in Fig 2. This frame assembly is suitable for supporting engine, wherein said frame assembly is being formed by two longitudinal frame side members, plurality of transverse cross members and outriggers. The cross members are provided for supporting the drive train components like engine, propeller shaft and for fixing all other related necessary items. Doors at different locations can be positioned by properly choosing the cross members location, without changing the frame assembly. Outriggers are the extensions of the cross members and bolted together with the frame side member and cross members instead of traditional welding. This results in weight saving and ease of manufacturing.

Outriggers form the base for the floor space in cases of low floor buses and they are provided with tapered plates for easy integration of frame with the body structure. In accordance with one aspect of the present invention, layout of front suspension unit is shown in Fig.3. The front suspension unit for one step entry low floor buses designed according to the present invention comprises a front axle suspended by plurality of air bellows arranged between the frame top and wheel in lateral direction and between frame and front axle in vertical direction, at both ends of said front axle; pluralities of air bellow brackets covering said air bellows at both the ends; pluralities of shock absorbers being mounted between said front axle and said air bellow brackets in vertical direction; pluralities of right and left rods called parallel links, preferably two, one end of each parallel link is secured pivotally to said chassis frame and other ends of which are being secured on side sections of front axle, wherein said parallel links are being arranged in the longitudinal direction of said chassis frame; plurality of lower rods called compound links or V link, one end of each is being secured to said chassis and other ends are being secured pivotally to a position near the center section of said front axle so as to from V shape; a front air bellow cross member mounted below said frame; and an anti roll bar, one end of which is being secured pivotally to said front axle in longitudinal direction and other is being secured to chassis. Compound links are mounted on the front axle without comprising on ground clearance.

Air bellows referred herein and exemplified as two bellows in figures; however, the front suspension may be provided with multiple air bellows, preferably four air bellows. Air bellows are being capable of supporting vertical loads by isolating the road undulations from getting transferred to vehicle chassis. Parallel and compound links are being capable of supporting braking/acceleration loads, whereas the cornering/lateral loads are also taken by compound links. The anti roll bar is being mounted to resist the vehicle roll during high speed cornering and shock absorbers are arranged to dampen suspension travel. In accordance with further aspect of the present invention, kinking is provided to longitudinal frame side members by bending said frame inwardly at a position near to air bellows mounting area for effectively packaging air bellows between frame and front wheels in lateral direction, and frame and said front axle in vertical direction.
In accordance with other aspect of the present invention, air bellow brackets mounted at both the ends of said frame axle are flushed with the frame top, and floor on air bellow brackets is extended. The flushing of air spring brackets is achieved by mounting the same in such a way that top of said bracket and said chassis frame are positioned at same level. The flushing of air bellow brackets and the arrangement of air bellows between the frame and wheel in lateral direction and between the frame and axle in vertical direction allows achieving minimum gangway width of at least 450 mm or more after entry plus one step, thereby maintaining uniform floor from front to rear of the vehicle at a height of about 650mm or less from the ground.

In accordance with further aspect of the present invention, placing a front door either in the front of the front axle or behind the front axle requires a minimum gangway requirement of at least 450mm or more after the entry and one step, by maintaining this minimum distance with engine bonnet on one side and wheel arch on another side. Therefore the front suspension unit realized according to present invention further capable of allowing placing a front door either in the front of the front axle or behind the front axle as shown in Fig 4 and Fig 5 respectively. Air bellows are referred herein and exemplified, without limitation, as a crimped air bellows in the Fig 3.The crimping process of air bellows helps in avoiding the mounting of one plate. As the available space for air bellow mounting plate is less, one plate has been removed from the assembly. The different disassembled suspension components of front suspension unit and other components associated with suspension components is shown in Fig 6. These components comprises front axle, parallel links, compound links, V rod MTG cross member, front cross member, outrigger, air bellow bracket, compound links, anti roll bar, hanger link assembly, shock absorbers and pedestal bracket, wherein said V rod MTG cross member is mounted on bottom of the frame. The front view of the proposed front air suspension according to present invention is shown in Fig 7.

The space occupied by mounting air bellows between the air bellow bracket and the front axle is shown by dimension D' in Fig 7, which is of at least 225mm. Therefore, components such as pedestal (air bellow mounting bracket on front axle), air bellows and air bellow bracket need to be packaged between the available space of 225mm, By taking into consideration of floor height from the ground for E+l front engine buses is of about 630mm or less is shown by dimension 'A', wheel radius (SLR) of at least 480mm is shown by dimension 'B', and axle drop of at least 75mm is shown by dimension 'D' in Fig 7. Therefore the available space for packaging is at least 225mm or less, i.e calculated as Available space for packaging suspension components = Frame height- SLR+Axle drop. This limited packaging space of 225 mm or less is used effectively by using the crimped air bellows i.e. top plate is crimped to the bellows and the brackets are flushed with the chassis to the extent of accommodating gangway width of at least 450mm or more, as discussed above. The foregoing description is a specific embodiment of the present invention.

It should be appreciated that this embodiment is described for purpose of illustration only. It is evident to those skilled in the art that although the invention herein is described in terms of specific embodiments thereof, there exist numerous alternatives, modifications and variations of the invention. It is intended that all such modifications and alterations be included insofar as they come within the spirit and scope of the invention as claimed or the equivalents thereof. Hence all variations, modifications and alternatives that fall within the broad scope of the appended claims come under gamut of the invention.

We claim:

1. A suspension unit for front wheels of one step entry front engine passenger vehicle comprises: a front axle and plurality of air bellows arranged between a chassis frame top and front wheels in lateral direction, and between said chassis frame and said front axle in vertical direction, at both the ends of said front axle by kinking longitudinal members of said chassis frame; and air bellow brackets mounted on each above said air bellow, wherein top of said bracket and said chassis frame are positioned at same level.

2. The suspension unit as claimed in claim 1, wherein said suspension unit comprises plurality of parallel links, wherein one end of each said parallel link is being secured pivotally to said chassis frame and other end of each link is being secured to said front axle by suitable means; and plurality of compound links, wherein one end of each said compound link is being secured pivotally to said chassis frame and other end of each link is being secured to said front axle by suitable means.

3. The suspension unit as claimed in claim 1, wherein said kinking of longitudinal frame members is defined by bending said frame members inwardly at a position near to air bellows mounting area.

4. The suspension unit as claimed in claim 1, wherein said suspension unit comprises a shock absorbing means mounted between each end of said front axle and said air bellow brackets, at both the ends of said front axle.

5. The suspension unit as claimed in claim 1, wherein said suspension unit comprises an anti roll bar, one end of which is being secured pivotally to said front axle in longitudinal direction and other is being secured to said chassis frame.

6. The suspension unit as claimed in claim 1, wherein said air bellow is preferably a crimped air bellow.

7. The suspension unit as claimed in claim 2, wherein said parallel links are being arranged in the longitudinal direction of said frame.

8. The suspension unit as claimed in claim 1, wherein said suspension unit comprises a front air spring cross member positioned at bottom of said chassis frame.

9. The suspension unit as claimed in claim 1, wherein said suspension unit allows to place front door either behind the front axle or in front of the front axle.

10. The suspension unit as claimed in claim 1, wherein said plurality of air bellows, plurality of parallel links and plurality of compound links are preferably two.

11. The suspension unit as claimed in claim 2, wherein said compound links are mounted on the front axle.

12. The suspension unit as claimed in claim 1, wherein said one step entry passenger vehicle as a floor height of at least 650mm or less from the ground.