FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)


TITLE OF THE INVENTION Novel Chassis Frame structure for Low Floor vehicles.
APPLICANTS
TATA MOTORS LIMITED, an Indian company
Having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Sashi Bhushan Pathak, Mr. Bivas Bhattacharyya and Mr. Sadanand
Renapurkar all Indian National of TATA MOTORS LIMITED,
An Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in
which it is to be performed.


FIELD OF INVENTION
The present invention relates to chassis frame of a vehicle and more particularly it relates to novel chassis frame structure of low floor vehicles.
BACKGROUND OF INVENTION
Low floor buses are a boon to the intra city applications worldwide. Conventional low floor vehicles having height of chassis up to 750 mm chassis height like. For passengers vehicles the chassis height required should be lower than the conventionally designed chassis height. So that people can alight the passenger vehicle comfortably. This is possible only if a height of chassis of passenger vehicles is lower than the existing chassis configuration. With the conventional or existing chassis design methods, the required floor height of the chassis of passenger vehicle is difficult to achieve. In order to address the aforesaid difficulties, new chassis frame structure of semi low floor vehicles has been developed. So that required chassis height of vehicle can be maintained to facilitate passenger to alight comfortably in to vehicle.
OBJECTS OF INVENTION
The main object of the present invention is to provide novel chassis frame structure of low floor vehicle.
Another object of the present invention is to provide novel chassis frame structure of low floor vehicle which facilitates easy entry of passenger.
Yet another object of the present invention is to provide novel chassis frame structure of low floor vehicle which is simple in construction and cost effective.
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STATEMENT OF INVENTION
Accordingly the present invention discloses, a Chassis Frame structure for Low Floor vehicles comprising:
a left hand (LH) long member and a right hand (RH) long member, said long members being made up of a plurality of members connected with each other, wherein at least one member is vertically offset with the remaining members;
a plurality of cross members provided to parallely connect said LH and RH long members to form a chassis frame of a vehicle; wherein
a substantially vertical drop down member is provided at substantially the centre of said LH and RH long members to connect said vertically offset members thereby providing a step in the chassis frame to achieve required low floor height;
said long members further comprising a hump shaped member at a front axle location in order to avoid hitting of the front axle with frame during bump condition.
BRIEF DESCRIPTION OF DRAWINGS
Figure-01 shows isometric view of vertical drop down connection means.
Figure-02 shows isometric view of front hump portion on the LH and RH long members.
Figure-03 shows isometric view of the novel chassis frame structure.
Figure-04 shows side view of the vertical drop down connection means.
Figure-05 shows top view of the vertical drop down connection means.
Figure-06 shows side view of front hump portion on Long members.
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BRIEF DESCRIPTION OF INVENTION
Novel Chassis Frame structure of Low Floor vehicles comprises;
LH Long member (1), RH long member (1') said LH and RH long members are made up of plurality of members (1, 2,3,4,5 and 6) connected with each other.
Said LH and RH long members are connected parallelly with each other with the help of plurality of cross members (7) to form a chassis frame of a vehicle.
Said LH and RH long member comprises drop down connection features provided for facilitating the required height of the chassis of a vehicle. Said long members are connected with vertical drop down channel member (8) with staggered type bolt arrangement and reinforcement (10). Said LH and RH Long members also comprises front hump portion (5) on chassis in line of front axle to prevent the hitting of axle during bump condition. Said front hump portion (5) having reinforcement which is welded with said LH and RH long member pieces (4, 6).
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Now referring to figure-01 to 06, in accordance with this invention, Novel Chassis Frame structure of Low Floor vehicles comprises;
LH Long member (1), RH long member (1'), said LH and RH long members are made up of plurality of pieces connected with each other.
Said LH and RH long members are connected parallelly with each other with the help of plurality of cross members (7) to form a chassis frame of a vehicle.
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Said LH and RH long member comprises drop down connection features provided for facilitating the required height of the chassis of a vehicle. Said long members are connected with vertical drop down channel member (8) with staggered type bolt arrangement and reinforcement (10). Said LH and RH Long members also comprises a hump shaped member (5,5') on chassis in line of front axle to prevent the hitting of axle during bump condition. Said front hump shaped member which is welded with said LH and RH long member pieces (4,6).
First (LH) and second (RH) long members comprises plurality of long member pieces (1, 2, 3, 4, 5 and 6) connected with each other. The said plurality of long member pieces are at least six pieces connected with each other by welding and bolting arrangement to form a LH and RH long member.
Said LH and RH long member comprises a substantially vertical drop down member at substantially the centre of said LH and RH long member for providing step in the frame of chassis to achieve the low floor height. Said drop down member has a vertical channel member (8) used to connect two vertically offset long member pieces. The said low floor height with said drop down connection means is approximately at least 650mm.
The said drop down connection means comprises vertical channel member (8) connected with vertically offset pieces of long members. The said vertical channel member (8) is connected with welding and bolting arrangement with the said vertically offset pieces of LH and RH portion of long members.
Support members (9) are provided between two said vertically offset pieces of long members (1, 2) sandwiched between them and joined with the help of welding. The said support member (9) is provided on both the LH and RH long members to provide necessary support and reinforcement.
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Said support member is a rectangular standard tube (9) is provided between the long members at location of the said drop-down. In this arrangement the height of both the long member is required to be maintained. So to ensure that exact floor height is maintained as well as to avoid the hitting of near axle with the frame, a rectangular standard tube (9) is welded between two pieces of long nember (1 and 2).
The drop down channel member (8) is preferably a C-type channel member provided to connect the said long members (1 and 2) by bolted joints. Staggered arrangement of bolts is used which ensures uniform distribution of stresses.
A reinforcement (10) of standard C- type channel nember with rectangular plates welded to long members at both ends is used. The said reinforcement (10) is bolted to the two ends of long members. The reinforcement (10) not only supports the frame at drop-down but also avoids excessive stresses in the drop-down area. Thus making the design viable and robust. To further avoid twisting of the frame, two cross members (7) are provided near the drop-down.
So a step is provided in the frame to achieve a floor height of 650 mm. With this low floor height of chassis, a passenger can enter the vehicle with two steps, the second step being entry step. In order to avoid hitting the chassis during bump condition, the front portion is configured suitably at the front axle position.
In order to avoid hitting the front axle with frame during bump condition, the front hump portion (5) is provided at the front axle position. This is manufactured using a special die. A separate tubular cross-member (11) is provided in the front hump area to avoid twisting of the frame and rigidly hold the humps together with frame.
The said hump is separate unit and it is welded to the long member of chassis. The said hump is provided at the front axle.
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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, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
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WE CLAIM:
1. A Chassis Frame structure for Low Floor vehicles comprising:
a left hand (LH) long member and a right hand (RH) long member, said long members being made up of a plurality of members connected with each other, wherein at least one member is vertically offset with the remaining members;
a plurality of cross members provided to parallely connect said LH and RH long members to form a chassis frame of a vehicle; wherein
a substantially vertical drop down member is provided at substantially the centre of said LH and RH long members to connect said vertically offset members thereby providing a step in the chassis frame to achieve required low floor height;
said long members further comprising a hump shaped member at a front axle location in order to avoid hitting of the front axle with frame during bump condition.
2. The Chassis Frame structure as claimed in claim 1 wherein a reinforcement member is provided at the vertical drop down portion of said chassis frame.
3. The Chassis Frame structure as claimed in claim 1 wherein said plurality of members includes at least six pieces connected with each other by welding and bolting arrangement to form a LH and RH long member.
4. The Chassis Frame structure as claimed in claim 1 wherein said vertical drop down member provides said step in the chassis frame to achieve a floor height of at
least 650 mm,
5. The Chassis Frame structure as claimed in claim 1 wherein said vertical drop
down member is welded and bolted with said vertically offset members of said LH
and RH long members.
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6. The Chassis Frame structure as claimed in claim 5 wherein rectangular tubular support members are sandwiched between said vertically offset LH and RH members at the location of said vertical drop-down member to maintain required floor height.
7. The Chassis Frame structure as claimed in claim 1 wherein said vertical drop down member is a C-type channel member connected to said long members by staggered bolting arrangement..
8. The Chassis Frame structure as claimed in claim 2 wherein said reinforcement is a C- type channel member with rectangular plates welded to said long members at both ends and two cross members are provided near said drop-down to further avoid twisting of said frame.
9. The Chassis Frame structure as claimed in claim 1 wherein said hump shaped member is joined to said long members from inside and a separate square tubular cross-member is provided at the vicinity of the hump shaped member to avoid twisting of the chassis frame.
10. A Chassis Frame structure of Low Floor vehicles largely as described in specification and as illustrated in accompanying drawings.
Dated this 17th day of February 2009
TATA MOTORS LIMITED By their Agent & Attorney

(Karuna Goleria) of DePENNING & DePENNING
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