Claims:We claim
1) A hydraulic seat suspension assembly (131) with electronic level sensing, comprising of :

a) a manifold (132) positioned at the back rest (133) of the operator seat;
b) a hydraulic pressure chamber (134) positioned within the said manifold (132);
c) a piston (135) having a first end (136) and a second end (137), wherein said second end (137) of the piston is operatively connected to the said hydraulic pressure chamber (134) via a cylinder rod, wherein the said first end (136) is connected to the back rest (133) of the operator seat to enable a up and down movement of the piston;
d) a hand pump (138) operatively coupled to the said hydraulic pressure chamber (134);
e) a handle (139), wherein said handle is in direct contact with the said hand pump (138);
f) atleast a pressure reduction valve (140) positioned at the top end of the hydraulic pressure chamber (134), wherein said pressure reduction valve (140) is operatively coupled to the said hydraulic pressure chamber;
g) atleast a reservoir (141) for storing the hydraulic fluid, wherein said reservoir (141) is in communication with the said hand pump (138) and said pressure reduction valve (140);
h) an accumulator (142) positioned at the bottom end of the said hydraulic pressure chamber (134);
i) an electronic sensing unit (143) positioned at the back rest of the operator seat, wherein said electronic sensing unit detects the position and pressure status of the operator seat based on the operator weight; and
j) a position indicator (144) having plurality of indication stages (144a, 144b,144c..), wherein said position indicator indicates the detected pressure and position status of the operator seat.

2) A hydraulic seat suspension assembly (131) as claimed in claim 1, wherein said hand pump (138) is a piston pump.

3) A hydraulic seat suspension assembly (131) as claimed in claim 1, wherein said hand pump (138) is mechanical hand pump operated manually by means of the said handle (139).

4) A hydraulic seat suspension assembly (131) as claimed in claim 1, additionally comprises of a diaphragm (145) appended to the said accumulator (142).

5) A hydraulic seat suspension assembly (131) as claimed in claim 1 & Claim 4, wherein volume of the said diaphragm (145) bladder is equivalent to the volume of the said accumulator (142).

6) A hydraulic seat suspension assembly (131) as claimed in claim 1 & Claim 4, wherein said diaphragm (145) is pre-charged with an inert gas to a predetermined pressure value of Po.

7) A hydraulic seat suspension assembly (131) as claimed in claim 1, 4 & 6, wherein said inert gas is selected from group consisting of argon, helium, nitrogen, neon and mixture thereof.

8) A hydraulic seat suspension assembly (131) as claimed in claim 1, 4 & 6, wherein said inert gas is nitrogen.

9) A hydraulic seat suspension assembly (131) as claimed in claim 1, wherein said accumulator (142) is a hydro-pneumatic accumulator.

10) A hydraulic seat suspension assembly (131) as claimed in claim 1, wherein said indication stages (144a,144b,144c) includes but are not limited to, low pressure, nominal pressure and over pressure indication stages.

11) A hydraulic seat suspension assembly (131) as claimed in claim 1 & 10, wherein said position indicators is a coloured light indicator.

12) A hydraulic seat suspension assembly (131) as claimed in claim 1 & 10, wherein said position indicators is a coloured LED light indicator.

13) A method of operation of the said hydraulic seat suspension assembly (131) with electronic sensing means, comprising the steps of :

k) maintaining the hydraulic fluid at a predetermined level in the said reservoir (141);
l) occupying the driver seat base (146) by the operator;
m) transferring of operation load and vibration from the said driver seat base (146) to the hydraulic pressure chamber (134) via the said piston (135), wherein said operation load and vibration are transferred in the form of pressure fluctuations;
n) detecting the pressure and position status of the driver seat by the electronic sensing unit (143);
o) indicating the detected pressure and position status by means of the corresponding indication stages (144a,144b,144c) of the said position indicator (144);
p) adjusting and /or regulating the said hand pump (138) and/or the pressure reduction valve (140) based on the status displayed on the position indicator (144), wherein said hand pump (138) is operated by means of the said handle (139);
q) compressing the inert gas contained in the diaphragm (145) of the said accumulator (142) by means of the hydraulic fluid contained in the reservoir (141) based on the pressure adjustment made by the hand pump (138) and/or pressure reduction valve (140), wherein the said reservoir (141) is in communication with the said hand pump and said pressure reduction valve;
r) balancing the exerted pressure of the compressed gas inside the diaphragm (145) of the accumulator by means of the hydraulic fluid from the said reservoir (141), wherein said position indicator (144) displays the corresponding pressure and position status at said indication stage;
s) adjusting and/or regulating the said hand pump (138) and/or the said pressure reduction valve (140) to enable the nominal position and pressure status to be displayed on the said indication stages of the position indicator; and
a) discharging the stored pressure in the form of energy on experiencing a decreasing pressure from the suspension system.

14) A method of operation of the said hydraulic seat suspension assembly (131) as claimed in claim 13, wherein operation of the said hand pump (138) by means of the said the said handle (139) pumps a predefined amount of hydraulic fluid from the reservoir (141) to the said hydraulic pressure chamber (134) and said accumulator (142), wherein said predefined amount of hydraulic fluid is based on the pressure exerted by the said hand pump.

15) A method of operation of the said hydraulic seat suspension assembly (131) as claimed in claim 13, wherein when the exerted pressure is high, the said pressure reduction valve (140) is regulated, wherein said hydraulic fluid from the said reservoir (141) to the said hydraulic pressure chamber (134) and said accumulator (142) is transferred by means of the said pressure reduction valve.

16) A method of operation of the said hydraulic seat suspension assembly (131) as claimed in claim 13, wherein said accumulator (142) and the diaphragm (145) contained therein remain stable when no vibration or load is exercised by the operator seat base (146).
, Description:FIELD OF THE INVENTION
The present invention relates to a seat suspension system for off-road vehicles, more particularly to a hydraulic seat suspension system for regulating the movement of vehicle seat in response to the operator load, providing an enhanced operator comfort during vehicle operation over rough uneven terrain.
BACKGROUND OF THE INVENTION
A suspension system in general supports or isolates a load, such as a cab or operator seat from the vehicle frame. The vibration experienced by the vehicle frame is an important factor to be considered while designing a good vibration isolator/ suspension system. Vibrations produces adverse effect on the productivity of work vehicles such as agricultural tractors, construction equipment, trucks etc in which the operator cab is supported on a chassis. The Vibrations experienced by such vehicles reduce their reliability, increase mechanical fatigue of components, and increases the levels of discomfort and fatigue to the operator. Such vehicles are usually operated over different types of terrain, including very rough off-highway surface and relatively smooth on-highway operation, often affects the seated operator over vehicle control decreasing the productivity and efficiency of the work vehicle. The vibrations exerted on the operators cab caused by different terrain types results in both qualitative and quantitative problems. The operator is also less likely to be satisfied with a work vehicle which provides poor ride quality. Thus to improve the ride quality and operator comfort, work vehicles have been conventionally equipped with different types of suspension systems to isolate the operator from vibrations caused by surface bumps.
Traditionally passive, semi-active or active suspension systems are mounted between the chassis and cab to isolate the operator from vibrations caused by vehicle operation. Passive systems uses different passive vibration isolators including rubber isolators, springs with friction, air bags to damp vibrations with different frequencies. Semi-active systems uses sensors to sense the cab movement and act accordingly by removing the energy from the system and gaining control over the damper. Active systems use sensors, controllers and actuators, which generates control signals and forces based on the sensed cab movement to cancel the vibrations transmitted to the cab by the chassis.
Providing vibration isolation for a vehicle frame is quite different than providing a wheel suspension system. In general the wheel suspension system which encounters occasional high speed motions are equipped with shock absorbers which displaces those large high speed motions without generating any large damaging loads on the vehicle. But the same is not the case with the suspension systems for vehicle frame which encounters different sets of vibrations from different parts of the vehicle. These vibrations which are transferred from other sources to the operator cab causes serious health concerns to the operators. Conventionally, most of the shock absorbers or suspension systems for mitigating the vibrations on the operators cab are built based on the principle of wheel suspension system which becomes ineffective for vehicle frame systems. Thus came the need for separate seat suspension systems which efficiently isolates the operator from the aggressions of vibration.
The controllability of the vehicle is enhanced and operator fatigue is reduced if the vehicle seat height is adjustable to a comfortable position based on the physical characteristics the operator. The existing seat suspension systems consists of mechanical springs and motion dampeners of leaf, coiled or air variety which are sometimes used in conjunction with conventional automotive shock absorbers. These types of height adjustable seat suspension systems usually works by manipulating the entire chassis upon which the operator cab is mounted. Additionally, their mechanisms for adjusting seat height are often comprised of multiple part mechanical linkages which are cumbersome and difficult to operate. Therefore, there exists a need in the art for a seat suspension system which mitigates the vibration exerted on the operator cab or seat providing a comfortable and high quality ride across different terrain types. Further it would also be desirable to have a vehicle seat suspension system which would absorb shocks and feature a height adjustable system based on the operator weight to a predetermined comfortable ride position.
US patent 6834736 relates to an active vehicle suspension system with a hydraulic spring which isolates the operator cab or seat from vibrations in the chassis of a vehicle. The said system comprises of a hydraulic actuator connected between the cab and the vehicle chassis and an accumulator coupled to the said hydraulic actuator that acts as a hydraulic spring to attenuate high frequency vibrations. Further a control valve selectively connects the hydraulic actuator to a source of pressurized hydraulic fluid or a reservoir. Sensors detect acceleration and displacement of the cab or seat to which a controller responds by operating the valve, this actively drives the hydraulic actuator to produce motion that counters the relatively low frequency vibrations from the chassis.
US patent 3990668 discloses a hydraulic suspension vehicle seat assembly includes an hydraulic actuator activated by a valve whose spool is directly connected by a two-link linkage to the seat. The valve is directly responsive to the geometry of the linkage to urge the seat, regardless of the load on the seat, to a ride position established by the linkage.
US patent document 6467748 provides a hydraulic circuit for active suspension system includes a hydraulic actuator coupled between the seat and the base, an pneumatic off-load device between the seat and the base, and a control system which actively controls the hydraulic actuator and the off-load member. The control system actively controls the hydraulic actuator as a function of a seat position error signal.
US patent No 5899288 discloses an active suspension system for a work vehicle consisting of an active vibration isolator mounted between the chassis and cab of the vehicle. The isolator includes mounts attached to the cab and the chassis, and a spring and a hydraulic actuator with a cylinder and a piston moveable therein. An elastomeric vibration isolator is connected in series with the actuator to damp high frequency vibrations. The actuator moves the cab relative to the chassis when pressurized hydraulic fluid is selectively supplied and relieved to the actuator by a valve assembly responsive to a valve control signal. A sensor measures movement between the piston and the chassis. A control circuit generates the valve control signal in response to the sensed signal to attenuate transmission of force between the cab and chassis.
The above cited prior-art documents deals with the hydraulic seat suspension systems which are used to attenuate the vibrations experienced by the vehicle operator. In all of the cited prior-art documents the suspension system is placed or disposed in-between the operator seat and chassis which mainly isolates the operator cab from the vibrations caused by terrain irregularity. None of the cited prior-art documents takes into account the operator's weight while determining the comfortable riding position. For the above reasons there exists a need in art to provide a hydraulic seat suspension system for off road vehicle featuring a height adjustment method based on the operator's weight providing a better driver comfort in terms of lesser vibration and shock.
The present invention provides a passive variable pressure hydraulic seat suspension with electronic level sensing for off-road vehicles. The present invention overcomes the above cited prior-arts by providing a hydraulic suspension system positioned at the back of the operator cab or seat which enables easy assembly and handling of the suspension system. Further the height adjustment is performed based on the operator weight, thus providing improved driver comfort and high quality ride by mitigating the vibrations and shocks experienced by the operator.
OBJECTIVE OF THE INVENTION
The main objective of the present invention is to provide a hydraulic seat suspension system with electronic level sensing for off-road vehicles.
Another objective of the present invention is to provide a hydraulic seat suspension system with height control based on the operator weight.
Still another objective of the present invention is to provide a hydraulic seat suspension system which indicates the pressure and position status of the driver seat with respect to the operator weight.
Yet another objective of the present invention is to provide a hydraulic seat suspension system which provides an improved driver comfort by mitigating the vibrations and shock experienced by the operator.
SUMMARY OF THE INVENTION
The present invention provides a hydraulic seat suspension assembly (131) with electronic level sensing, for off-road vehicles, comprising of : a manifold (132); a hydraulic pressure chamber (134) positioned within the said manifold (132); a piston (135) operatively connected to the said hydraulic pressure chamber (134); a hand pump (138); a handle (139), wherein said handle is in direct contact with the said hand pump (138); atleast a pressure reduction valve (140); atleast a reservoir (141), wherein said reservoir (141) is in communication with the said hand pump (138) and said pressure reduction valve (140); an accumulator (142); an electronic sensing unit (143), wherein said electronic sensing unit measures the pressure and position status of the driver seat based on the operator weight; and a position indicator (144) having plurality of indication stages (144a, 144b,144c..), wherein said position indicator indicates the detected pressure and position status of the operator seat. The present invention additionally comprises of a diaphragm (145) appended to the said accumulator (142), wherein the said diaphragm (145) is pre-charged with an inert gas to a predetermined pressure value (Po).
In an embodiment of the present invention, on experiencing an increased system pressure in the hydraulic pressure chamber (134) over the said predetermined pre-charged pressure (Po) value, the hydraulic fluid contained in the reservoir (141) compresses and balances the compressed gas inside the diaphragm at a maximum working pressure of P2. This absorbs and compensates the vibrations and shock experienced by the operator in the driver seat.
In another embodiment of the present invention, on experiencing a decreasing system pressure in the hydraulic pressure chamber (134), wherein the said accumulator (142) with a diaphragm (145) containing compressed gas at pressure P2 releases the stored pressure in the form of energy, which enables the operator to perform several operations on the said hydraulic system, wherein said pressure of the compressed gas inside the diaphragm (145) of the said accumulator (142) reaches a minimum working pressure (P1).
In still another embodiment of the present invention, when no vibration or load is exercised by the operator seat base (146) there exist no transmit of pressure to the said hydraulic pressure chamber (134) and thus the said accumulator (142) and the diaphragm (145) contained therein remain stable.
The present invention also teaches the method of operation and working of the said hydraulic seat suspension system with electronic sensing unit. The hydraulic seat suspension assembly (131) of the present invention enables an optimal height control of the operator seat based on the operator weight thereby mitigating the vibrations and shock experienced by the operator. This reduces the vertical motion of the seat and thereby achieving effective vibration damping and improved driver comfort.
BRIEF DESCRIPTION OF THE DIAGRAMS
Figure 1 shows the schematic layout of the hydraulic seat suspension system of the present invention.
Figure 2 depicts the perspective view the hydraulic seat suspension system of the present invention.
Figure 3 represents the block diagram of the hydraulic seat suspension system of the present invention.
Figure 4 (a-d) illustrates the working of the accumulator of the present invention with diaphragm contained therein.
Figure 5 represents the circuit diagram of the electronic level sensing unit of the present invention.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention as embodied by the "Hydraulic seat suspension system and method thereof", succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The present invention provides a hydraulic seat suspension assembly (131) with electronic level sensing, comprising of : a manifold (132) positioned at the back rest (133) of the operator seat; a hydraulic pressure chamber (134) positioned within the said manifold (132); a piston (135) having a first end (136) and a second end (137), wherein said second end (137) of the piston is operatively connected to the said hydraulic pressure chamber (134) via a cylinder rod, wherein the said first end (136) is connected to the back rest (133) of the operator seat to enable a up and down movement of the piston; a hand pump (138) operatively coupled to the said hydraulic pressure chamber (134); a handle (139), wherein said handle is in direct contact with the said hand pump (138); atleast a pressure reduction valve (140) positioned at the top end of the hydraulic pressure chamber (134), wherein said pressure reduction valve (140) is operatively coupled to the said hydraulic pressure chamber; atleast a reservoir (141) for storing the hydraulic fluid, wherein said reservoir (141) is in communication with the said hand pump (138) and said pressure reduction valve (140); an accumulator (142) positioned at the bottom end of the said hydraulic pressure chamber (134); an electronic sensing unit (143) positioned at the back rest of the operator seat, wherein said electronic sensing unit detects the position and pressure status of the operator seat based on the operator weight; and a position indicator (144) having plurality of indication stages (144a, 144b,144c..), wherein said position indicator indicates the detected pressure and position status of the operator seat.
In the preferred embodiment, wherein the said hand pump (138) is a piston pump, wherein said hand pump (138) is mechanical hand pump operated manually by means of the said handle (139).
The present invention additionally comprises of a diaphragm (145) appended to the said accumulator (142), wherein volume of said diaphragm bladder is equivalent to the volume of the said accumulator. The said diaphragm (145) is pre-charged with an inert gas to a predetermined pressure value (Po) (Fig. 4b),wherein said inert gas is selected from group consisting of argon, helium, nitrogen, neon and mixture thereof, more preferably nitrogen.
In an embodiment of the present invention, on experiencing an increased system pressure in the hydraulic pressure chamber (134) over the said predetermined pre-charged pressure (Po) value, the hydraulic fluid contained in the reservoir (141) compresses the inert gas contained in the diaphragm (145) of the said accumulator (142), wherein said hydraulic fluid balances the compressed gas inside the diaphragm at a maximum working pressure of P2 (Fig. 4c), wherein P2 is the relief pressure or maximum working pressure of the said hydraulic suspension system.
In an embodiment of the present invention, on experiencing a decreasing system pressure in the hydraulic pressure chamber (134), wherein the said accumulator (142) with a diaphragm (145) containing compressed gas at pressure P2 releases the stored pressure in the form of energy, which enables the operator to perform several operations on the said hydraulic system, wherein said pressure of the compressed gas inside the diaphragm (145) of the said accumulator (142) reaches a minimum working pressure (P1)(Fig 4d).
In the preferred embodiment of the present invention, wherein said accumulator (142) is a hydro-pneumatic accumulator.
In an embodiment of the present invention, wherein said position indicator (144) consists of plurality of indication stages (144a,144b,144c) including but not limited to, low pressure, nominal pressure and over pressure indication stages, wherein said indicators are coloured light indicators, wherein said indicators are preferably coloured LED light indicators. The said electronic sensing unit (143) detects the pressure and position status of the operator seat based on the operator weight, wherein the detected pressure and position status is displayed on the said position indicator (144) by means of the corresponding indication stages (144a,144b,144c).
The method of operation of the said hydraulic seat suspension assembly (131) with electronic sensing means, comprises the steps of:
a) maintaining the hydraulic fluid to a predetermined level in the said reservoir (141);
b) occupying the driver seat base (146) by the operator;
c) transferring of operation load and vibration from the said driver seat base (146) to the hydraulic pressure chamber (134) via the said piston (135), wherein said operation load and vibration are transferred in the form of pressure fluctuations;
d) detecting the pressure and position status of the driver seat by the electronic sensing unit (143);
e) indicating the detected pressure and position status by means of the corresponding indication stages (144a,144b,144c) of the said position indicator (144);
f) adjusting and/or regulating the said hand pump (138) and/or the pressure reduction valve based on the status displayed on the position indicator (144), wherein said hand pump (138) is adjusted by means of the said handle (139);
g) compressing the inert gas contained in the diaphragm (145) of the said accumulator (142) by means of the hydraulic fluid contained in the reservoir (141) based on the pressure adjustment made by the hand pump (138) and/or pressure reduction valve (140), wherein the said reservoir (141) is in communication with the said hand pump and said pressure reduction valve;
h) balancing the exerted pressure of the compressed gas inside the diaphragm (145) of the accumulator by means of the hydraulic fluid from the said reservoir (141), wherein said position indicator (144) displays the corresponding pressure and position status at said indication stage;
i) adjusting and/or regulating the said hand pump (138) and/or pressure reduction valve (140) to enable the nominal position and pressure status to be displayed on the said indication stages of the position indicator; and
j) discharging the stored pressure in the form of energy on experiencing a decreasing pressure from the suspension system.

In the preferred embodiment of the present invention, wherein operation of the said hand pump (138) by means of the said the said handle (139) pumps a predefined amount of hydraulic fluid from the reservoir (141) to the said hydraulic pressure chamber (134) and said accumulator (142), wherein said predefined amount of hydraulic fluid is based on the pressure exerted by the said hand pump, wherein said hydraulic fluid is pumped to the said hydraulic pressure chamber (134) and said accumulator (142) via a non-return valve (not shown) on the said hand pump (138).

In the preferred embodiment of the present invention, wherein when the exerted pressure is high, the said pressure reduction valve (140) is regulated, wherein the said hydraulic fluid from the said reservoir (141) to the said hydraulic pressure chamber (134) and said accumulator (142) is transferred by means of the said pressure reduction valve.

In an embodiment of the present invention, when no vibration or load is exercised by the operator seat base (146) there exist no transmit of pressure to the said hydraulic pressure chamber (134) and thus the said accumulator (142) and the diaphragm (145) contained therein remain stable.

In another embodiment of the present invention, whenever the said operator seat base (146) experience a load or vibration, the said load and vibrations are transferred as pressure fluctuations to the said hydraulic pressure chamber (134) via the said piston (135), wherein the said pressure fluctuations are absorbed by the compressed inert gas contained in the diaphragm (145) of the said accumulator (142) and are balanced by the hydraulic fluid from the reservoir (141). This compensates the vibrations and other vertical load exerted on the operator seat, thus achieving vibration damping and effectively reducing the vertical motions and other disturbances experienced by the operator.

In still another embodiment of the present invention, the hydraulic suspension system (131) of the present invention is provided with an automatic level control system, wherein on detecting the position and pressure status of the operator seat by means of an electronic sensing system, the control system will determine the optimum height of the operator seat and is automatically adjusted by way of electro-mechanical levelling means.
The hydraulic seat suspension assembly (131) of the present invention provides an electronic sensing system which measures and detects the optimal pressure and position status of the driver seat based on the operator weight. The optimal height control of the operator seat based on the operator weight mitigates the vibrations and shock experienced by the operator. This reduces the vertical motion of the seat and thereby achieving effective vibration damping and improved driver comfort.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.