FORM 2
THE PATENT ACT 1970
(39 OF 1970)
THE PATENT RULES, 2005
COMPLETE SPECIFICATION SEE SECTION 10; RULE 13)
TITLE OF THE NVENTION
"A SELF-LEVELLING HYDRAULIC SUSPENSION SYSTEM FOR A VEHICLE CABIN"
APPLICANT(S):
TATA MOTORS LIMITED
An Indian Company
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400 001,
Maharashtra, India.
PREAMBLE TO THE DESCRIPTION
The following specification partcularly describes the invention and the manner in which t is to be performed.

FIELD OF THE NVENTION
[0001] The present invention elates to a suspension system for a vehicle cabin and, more parculary, to a selfevellng hydraulc suspenson ysem or a vehicle cabin.
BACKGROUND OF THE NVENTION
[0002] A primary aim of any suspension ystem of vehicle is to provide a vehicle with a suspension that simultaneously resists dive, squat and roll to provide a comforable ride while maintaining equal pressure on all wheels. Generally as the vehicle traverses the ground, it will pass over rough, uneven surfaces. When a wheel encounters any unevenness in the ground surface, it is forced to follow the contours causing the variation in the load in the vehicle hrough that wheel and load unbalance amongst four wheels. Many designs of suspension systems have been developed for the equalization of the loads on the wheels of the vehicle and comort o the drver against dierent road conditons
[0003] In conventional vehicles, a fully suspended truck cabin use a combination of a coil spring and a damper at a front and a rear side. Though this type of suspension isolates most fequencies, at low frequencies there is attenuation at drivers seating point Alternatively, a rubber isolation in combination with the prng and the damper is employed in some cases. However, there is no attenuation in this case but isolation eficiency in high frequency range is not sufficient. In both of the above cases, in addition to vertical movements, a cabin also experiences pitch and roll movement Furher, cost of fuly suspended type cabin uspenson s also on a higher sde.

[0004] Therefore, there is a need for efficient suspension system or a cabin of the vehicle is needed that overcome the above mentoned problem
OBJECT OF THE NVENTION
[0005] The principal object of the embodiments herein is to provide a self-evelling hydraulic suspension system for a vehicle cabin. The suspension system ncluding four hydraulic units connected to a cabin of a vehicle to provide enhanced
riding and comort level to the drver of the vehicle maintaining balancing weight
of the cabin.
[0006] Another object of the embodiments herein is to provide a self-evelling hydraulic suspension mechanism such that all the four hydraulc units eacts smultaneousy to movements of the vehicle cabin.
SUMMARY OF THE NVENTION
[0007] In one aspect the obj ect is satisfied by providing a suspension system for a vehicle cabin. The suspension system includes four hydraulic units connected with each other using hydraulic pipes. Each of the four hydraulic units is connected to a cabin of the vehicle at one end and is mounted on a mounting location of a chassis of the vehicle at other end. The one or more hydraulic pipes connected to each of the four hydraulic units to allow communication between each of the four hydraulic units. During operation with the suspension system installed on the vehicle, movement of the chassis of the vehicle at any of the mounting location flows fluid to a first hydraulic unit of the four hydraulic units and to remaining three hydraulic units of the four hydraulc units through the hydraulic pipes at same time to enable all the four hydraulc units to smultaneousy react to the movement of the chass of the vehicle.

[0008] In an embodiment, each of the four hydraulc units includes a rod, a
sliding mass connected to the rod, an inner tube, an outer tube, a plate, and a bush.
The sliding mass of each of the hydraulc units is connected to the cabin of the
vehicle with the rod. The inner tube and the outer tube connected to the chassis of
he vehicle. The outer tube of all the four hydraulic units are interconnected with
he hydraulic pipes. The plate is connected at an end of the inner tube and the outer
ube to create three hydraulc chambers. The bush and guide provide support to the
od. During operation, the sliding mass along wih the rod reciprocates in the inner
ube and wherein the rod s uppored and guided by he bush durng he
eciprocation of the rod.
[0009] In an embodiment, the hydraulic chamber is created inside the inner tube, the hydraulic chamber is created between the slding mass and the closing plate and the hydraulc chamber is created n between the inner tube and the outer ube.
[0010] n an embodiment, the hree hydraulc chambers are completely ed wih the fuid.
[0011] In an embodiment, a first set of holes are provided on a periphery of he inner tube and a second set of holes are provided on the siding mass to allow the fluid to flow from one hydraulc pipe to another hydraulc pipe of the one or more hydraulc pipes
0012] n an embodiment, when C.G. of the cabin of the vehicle shifts on one side, the sliding mass is moved in a downward direction to move the fluid from he hydraulic chamber to the hydraulic chamber and he hydraulc chamber (no?) hrough the second set of holes in the sding mas

[0013] In an embodiment, due to presence of the first set of holes and the second set of holes, an equal presure of the fuid is developed in the three hydraulic chambers
[0014] In an embodiment, the second set of holes provided on the sliding mass of diferent diameters to generate damping force in the suspenson sysem
0015] In an embodiment the flow of the fluid into the four hydraulic units due to the movement of the chasis of the vehicle creates a friction between layers of the fluid that are moving relative to each other to generate a secondary damping orce in the suspenson sysem
[0016] In an embodiment, the fow of the fuid in any one of the four hydraulic units raises the presure of the fuid equally in all the four hydraulic unit
[0017] These and other aspects of the embodiments herein will be better appreciated and understood when considered n conjunction with the following description and the accompanying drawings. It should be understood, however, that he following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departng from he pirt thereof, and he embodiments herein nclude all such modications
BRIEF DESCRIPTION OF DRAWNGS
0018] The proposed self-levelling hydraulic suspenson system is llustrated in the accompanying drawings, throughout which like reference letters ndicate coresponding parts in the varous fgures The embodiments herein wil be

better underood fom he following description wih reference to the drawings in which:
[0019] FIG. la illustrates a front view of a suspenson sysem or a vehicle cabin, according to embodiments as disclosed herein;
[0020] FIG. lb illustrates a side view of the suspenson ysem, according o embodiments as disclosed herein;
[0021] FIG. 2 illustrates a perspective view of hydraulic unit of he uspension sysem, according to embodiments as disclosed herein;
[0022] FIG. 3 illustrates a perspective view of the hydraulic unit balancing a weight of a cabin of the vehicle, according to embodiments as diclosed herein; and
[0023] FIG. 4 illustrates a perspective view of the hydraulic unit generating a damping force, according to embodiments as diclosed herein.
DETAILED DESCRIPTION OF THE NVENTION
[0024] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the
ollowing description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necesarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term "or" as used herein, refers to a non-exclusive or unless otherwise ndicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be consued as lming
he scope of the embodiments herein.

[0025] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substtutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements these elements should not be limited by these term These terms are generally only used to dinguih one element fom another
[0026] Referring now to the drawings, and more parculary to FIGS. 1-4, here are shown preferred embodiment
[0027] FIG. la illustrates a front view of a suspension system (10 for a vehicle cabin, according to embodiments as disclosed herein. The suspension system (1) includes four hydraulic units (2) connected through one or more hydraulic pipes (5) Each of the four hydraulc units (2) is connected to a cabin (3) of the vehicle and is mounted on a mounting location of a chassis (4) of the vehicle. The one or more hydraulic pipes (5) are connected to each of the four hydraulic units (2) to allow communication between each of the four hydraulic units (2). During operation with the suspension system (1) installed on the vehicle, movement of the chassis (4) of the vehicle at any of the mounting location flows fluid to a firt hydraulic unit of the four hydraulic units (2) and to remaining three hydraulic units of the four hydraulic units (2) through the hydraulc pipes (5) at same time to enable all the four hydraulic units (2) to simultaneousy react to the movement of the chassis (4) of the vehicle. The fow of the fluid in all the four hydraulc units (2) equally raises a presure of the fuid in all the four hydraulc units (2)

[0028] FIG. lb illustrates a side view of the suspension system (1), according to embodiments as disclosed herein. In an embodiment, all the four hydraulic units (2) are interconnected with the hydraulic pipes (5). This makes the luid to flow easily from one hydraulic unit to another through the hydraulic pipes 5). The movement of the chassis (4) at any of the mounting location of the cabin 3) creates a flow of the fluid in that particular hydraulic unit. At the same time, oil flows to other three hydraulic units since they are connected to each other The movement of the fluid causes equal pressure rise in all the four hydraulic units (2) Thus all four hydraulic units (2) reacts simultaneousy to vehicle chassis movement Self levellng tendency is achieved due to this presure re of the fuid.
[0029] FIG. 2 illustrates a perspective view of hydraulic units (2) of the suspenson system (1), according to embodiments as disclosed herein. Each of the hydraulic units (2) includes a rod (6), a sliding mass (7) connected o he rod 6) an inner tube (8), an outer tube (9), a plate (10), and a bush (14)
[0030] The sliding mass (7) of each of the hydraulic units (2) is connected o the cabin (3) of the vehicle through the rod (6). The inner tube (8) and the outer tube (9) are connected to the chassis (4) of the vehicle hrough the connecting element (10). The outer tube (9) of all the four hydraulic units (2) are interconnected with the hydraulic pipes (5). A fist set of holes (15) are provided on a periphery of he inner tube (8) and a econd set of holes (16) are provided on the sliding mass (7) to allow the fluid to flow from one chamber to another inside the inner tube (8) and outer tube (9) The outer tube (9) has an opening (17) for hydraulc pipe.
[0031] The plate 10) is connected at an end of the inner tube (8) and the outer tube (9) to create three hydraulic chambers (11, 12, and 13). Each of the hydraulic chambers (11, 12, and 13) are completely fled with the fluid. In an embodiment, the hydraulc chamber (11) is created nsde the nner tube 8) the

hydraulic chamber (12) is created between the sliding mass (7) and the closing plate (10) and the hydraulc chamber (13) is created in between the inner tube (8) and the outer tube (9)
[0032] The bush (14) provides support and guide to the rod (6). During the operation, the sliding mass (7) along with the rod (6) reciprocates in the inner tube 8) and wherein the rod (6) is suppored and guided by he bush 14) durng he eciprocation of the rod (6)
[0033] FIG. 3 illustrates a perspective view of the hydraulic unit (2) balancing a weight of a cabin of the vehicle, according to embodiments as disclosed herein. When a CG of the cabin (3) of the vehicle shifts to one side, the sliding mass (7) is pushed in a downward direction. This causes the fluid to move from the hydraulic chamber (11) to the hydraulc chamber (12) through the first set of holes (15) and to the hydraulic chamber (13) hrough the second set of holes (16) However, unequal area on either side of sliding mass (7) causes net displacement of the fluid from chamber (11) to chamber (12) and (13). This creates a presure rise which s proportional to net displaced of the luid, bulk modulus of the fluid and total fluid volume. Due to the set of holes (15) and (16) equal pressure is developed in hydraulic chambers (11, 12, and 13). Unequal area on either side of sliding mass (7) produces an exact force unbalance that is required o balance the weight of the cabin 3)
[0034] FIG. 4 llustrates a perspective view of the hydraulic unit (2) generating a damping force, according to embodiments as disclosed herein. The damping force described herein is primary damping force and a secondary damping orce generated due to the movements of the vehicle and vehicle cabin.

[0035] The second set of holes (16) provided on the sliding mass (7) are of different diameters to generate a primary damping force in the suspension system
1). When there is a movement in vehicle chassis (4), the fluid flows chamber (11) to chamber (12) through these second set of holes (16) which acts like an orifice and hence the primary damping force in the suspenson sysem 1) is generated due
o orce action.
[0036] Additionally, the first set of holes (15) provided on the periphery of the inner tube (8) for interconnecting the hydraulic chambers (11, 12, and 13) to generate a secondary damping force in the uspension system (1). Further movement of vehicle chassis (11) creates a flow of oil amongst these three chambers. The movement in vehicle chassis (4) creates a flow of the fluid amongst he hydraulic chambers (11, 12, and 13) creating a friction between layers of the fluid that are moving relative to each other and hus generates he econdary damping force in the suspenson sysem 1)
[0037] Unlike the conventional suspension system, a simple and cost effective design of the suspension system with few number of components is provided. The proposed suspenson ystem achieves low uspenson or ysem
ness and effective vibration iolation across spectrum
[0038] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such pecific embodiments without departng from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of lmiation. Therefore, while he embodiments

herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifcation wihin the spirt and scope of the embodiments as described herein.
0039] Following are the reference numerals

Numeral Descripton
1 Suspenson sysem
2 Four hydraulic units
3 Cabin
4 Chass
5 Hydraulic pipes
6 Rod
7 Slding mass
8 nner tube
9 Outer tube
10 Plate
11,12, and 13 Hydraulic chambers
14 Bush
15 Fit set of holes
16 Second set of holes
17 Opening for hydraulic pipe

We Claim:
1. A suspension ysem 1) or a vehicle cabin, he uspenson ysem 1)
comprising:
at least four hydraulic units (2) connected to a cabin (3) of the vehicle, wherein each of he four hydraulic units 2) are mounted on a mountng ocation of a chassis (4) of the vehicle; and
a plurality of hydraulic pipes (5) connected to each of the four hydraulc units (2) to allow hydraulc communication between each of the four hydraulc units (2),
wherein during operation wih he suspension system (1) installed on the
vehicle, movement of the chassis (4) of the vehicle at any of the mounting
ocation flows fluid to a firt hydraulic unit of the four hydraulic units (2) and
to remaining three hydraulic units of the four hydraulic units (2) through the
hydraulic pipes (5) at same time to enable all the four hydraulic units (2) to
multaneousy react to the movement of the chass (4) of the vehicle.
2. The suspension system (1) as claimed n claim 1, wherein each of the our
hydraulic units (2) compres
a rod (6);
a sliding mass (7) connected to the rod (6), wherein the siding mass (7) of each of the hydraulic units 2) is connected o he cabin 3) of the vehicle hrough the rod (6);
an inner tube (8) and an outer tube (9) connected to the chassis (4) of the vehicle, wherein he outer ube (9) of all the our hydraulc units 2) are nterconnected with the hydraulic pipes (5);
a plate (10) connected at an end of the inner tube (8) and the outer tube (9) o create a plurality of hydraulic chambers (11, 12, 13);
a bush (14) to provide support and guide o the rod (6)

wherein during operation, the sliding mass (7) along wih the rod (6) reciprocates in the inner tube (8) and wherein the rod (6) is suppored and guided by the bush (14) durng the reciprocation of the rod (6)
3. The suspension system (1) as claimed in claim 2, wherein the hydraulic chamber (11) is created nside the inner tube (8), the hydraulic chamber (12) is created between the sliding mass (7) and the closing plate (10) and the hydraulc chamber (13) is created in between the inner tube (8) and the outer tube (9)
4. The suspension system (1) as claimed in claim 2, wherein he pluraliy of hydraulc chambers (11, 12, 13) are completely fed wih the fuid.
5. The suspension system (1) as claimed in claim 2, wherein a first set of holes
15) are provided on a periphery of the inner tube (8) and a second set of holes
(16) are provided on the sliding mass (7) to allow he uid o ow om one
hydraulc chamber to another hydraulc chamber
6. The suspension system (1) as claimed in claim 5, wherein when CG of the cabin
(7) of the vehicle shifts on one side, the sliding mass (7) is-forced in a downward
direction to move the fluid from the hydraulic chamber (11) to the hydraulic
chamber (13) and the hydraulc chamber (12) through he second et of holes
16) in the sding mass (7)
7. The suspension system (1) as claimed in claim 5, wherein through the fst set of holes (15) and the second set of holes (16), an equal pressure of the fuid s developed in the pluraliy of hydraulc chambers (11, 12, 13)
8. The suspension system (1) as claimed in claim 5, wherein the second set of holes (16) provided on the sding mass (7) are of dierent diameters to generate

a difference in presure of the fuid to generate a prmary damping force in the uspenson sysem 1) through the orce action.
9. The suspension system (1) as claimed in claim 1, wherein the flow of the fluid
amongst the hydraulic chambers (11,12,13) into the four hydraulic units (2) due
o the movement of the chassis (4) of the vehicle creates a friction between layers of the fluid that are moving relative to each other to generate a secondary damping force in the suspenson sysem 1)
10. The suspension system (1) as claimed in claim 1, wherein the fow of the fuid
n any one of the four hydraulic units (2) equally raises a presure of the fuid
n all the four hydraulic units (2)