FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION IMPROVED COOLING SYSTEM OF HYDRAULIC POWER STEERING
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
Sagar S Ade, Narayan D Jadhav and K Gopalakrishna
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 Complete specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to the fields of power steering systems for vehicles. The present invention specifically relates to an improved cooling system of hydraulic power assisted steering.
BACKGROUND OF THE INVENTION
Hydraulic power assisted steering system is a power steering system fitted on any vehicles, particularly on heavy-duty vehicles. FIG. 1 shows a schematic diagram of a conventional hydraulic power steering circuit in accordance with a prior art. In case of conventional hydraulic power steering system as shown in FIG. 1, the power steering pump (2) adjacent to the engine (5) of the vehicle takes oil from a reservoir (1) and then pumps the oil to a steering gear box (3), arranged near or close to a radiator (6), at high pressure. The steering oil from the steering gearbox (3) is transported to the reservoir (1) at low pressure for further recycling of the steering oil. Such hydraulic power steering system generates lot of heat in the steering fluid or oil, especially in heavy-duty off-road conditions. This heat generation causes oil temperature to exceed safe operating temperature of steering components.
Furthermore, if the steering oil temperature is not controlled within an acceptable temperature level of the steering components, then the high temperature rise in the steering oil can lead to sudden failure of the steering components and cause oil seals and oil to break down and wear out more quickly, which leads to frequent change of oil as well as oil seals. In addition, the life of flexible hoses used in the hydraulic circuit is less due to high oil temperature. Such sudden failure of the power steering
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components may also cause loss of vehicle control, which creates potentially dangerous situation for the driver and other passengers.
In order to address the above disadvantages of prior art, an improved cooling system is developed for hydraulic power steering system, which continuously cools the oil in the hydraulic circuit of power steering and reduces the oil temperature for safety and reliability of the steering components and oil seals.
OBJECTS OF THE INVENTION
The main object of the present invention is to provide an improved cooling system of a hydraulic power steering system with maximum safety of driver and other passengers.
Another object of the present invention is to provide an improved cooling system of hydraulic power steering with simple construction and higher reliability with longer oil change interval.
SUMMARY OF THE INVENTION
According to one aspect, the present invention, which achieves the objectives, relates to an improved cooling system for a hydraulic power steering system of a vehicle comprises a reservoir configured for storage of steering oil. A power steering pump for pumping and/or pressurizing the steering oil, and a steering gear box for transmitting power to turn the wheels of front axle or rear axle or all axles available in the vehicle. An oil cooler is disposed in front of a radiator of a vehicle such that hot oil from the steering gear box passes through the oil cooler for cooling the
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steering oil by ram air or any other fluid and after cooling returns back the steering oil to the reservoir.
An improved cooling system, in accordance with this invention, wherein said oil cooler and/or heat exchanger fitted anywhere in the hydraulic circuit, which can be cooled by air or any other fluid and fitted in any orientation at any location in the
vehicle.
An improved cooling system, in accordance with this invention, wherein said oil cooler is formed of horizontal and/or parallel flow type for cooling the hydraulic oil by air or any other fluid.
An improved cooling system, in accordance with this invention, wherein said oil cooler is formed of horizontal vertical flow for cooling the hydraulic oil by air or any other fluid.
An improved cooling system, in accordance with this invention, wherein said oil cooler is formed of single tube type, cross flow type and/or combination of two or more types for cooling the hydraulic oil by air or any other fluid.
An improved cooling system, in accordance with this invention, wherein said power steering pump can be driven by either engine or electric power or pneumatic power or combination of two or more power sources.
An improved cooling system, in accordance with this invention, wherein said steering gear box can be used to turn wheels of front axle or rear axle or all axles available in the vehicle with the help of hydraulic fluid.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic diagram of a conventional power steering circuit, in
accordance with a prior art.
FIG. 2 illustrates a schematic diagram of a cooler running hydraulic power steering
circuit, in accordance with an exemplary embodiment of the present invention.
FIG. 3 illustrates a horizontal parallel flow cooler, in accordance with an exemplary
embodiment of the present invention.
FIG. 4 illustrates a vertical parallel flow cooler, in accordance with an exemplary
embodiment of the present invention.
FIG. 5 illustrates a single tube cooler, in accordance with an exemplary embodiment
of the present invention.
DETAILED DESCRIPTION OF THE 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 FIGS. 2 to 5, in accordance with the present invention, an improved cooling system for a vehicle hydraulic steering system comprises an oil reservoir (11) that is configured for storing hydraulic fluid, i.e. steering oil. A power steering pump (12) receives the steering oil from the reservoir (11) and then pumps and/or pressurizes the steering oil to a steering gear box (13) at high pressure. The power steering pump (12) is positioned adjacent to an engine (15) of the vehicle. The steering gear box (13) transmits power to turn the wheels of front axle or rear axle or
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all axles available in a vehicle using the steering oil. The steering oil at high temperature from the steering gear box (13) returns to an oil cooler (14) that is disposed in front of a radiator (16) of the vehicle. The oil cooler (14) cools the steering oil by incoming air from the radiator (16) and then returns the cooled steering oil to the reservoir (11). Note that the same reference numerals are assigned to identical components in FIGS. 2-5.
Furthermore, the oil cooler (14) acting as a heat exchanger can be fitted anywhere in the hydraulic circuit and in any orientation at any location in the vehicle. Such oil cooler (14) can be formed of any type, for example, horizontal parallel flow type, horizontal vertical flow type, single tube type, cross flow type or combination of two or more types for cooling oil by air or any other fluid. The power steering pump (12) can be driven either by the engine (15) or electric power or pneumatic power or combination of two or more power sources.
When the vehicle is in a running condition, the steering pump (12) is driven by the engine (15) of the vehicle to receive the steering oil from the reservoir (11) and delivers the oil to the steering gear box (13). If the driver turns the steering, i.e. steering gear box (13), the resistance to flow of oil is created thereby producing power assist for reduction in effort applied by the driver. Then, the temperature of the oil increases due to high pressure in steering circuit. The oil at high temperature enters into the oil cooler (14), such that the oil gets cooled by incoming air due to fan in the radiator (16) as well as vehicle motion.
Moreover, if there is no steering input given by the driver, then the oil passes, without any resistance, through the steering gear box (13) to the oil cooler (14) and later to the reservoir (11). The oil cooler (14), as shown in FIG. 3, is formed of
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horizontal parallel flow type. Fins (141) of the oil cooler (14) are arranged in parallel with the flow of oil, where the steering oil flows from one side to other side in horizontal direction. Similarly, the oil cooler (14) as shown in FIGS. 4 and 5, is formed of vertical parallel flow type and single tube type, respectively. The fins (141) provided in the oil cooler (14) can improve cooling effect by additional surface area. The fins can be constructed in such a manner to allow the air from a frontal area of the vehicle, to flow through it, thereby cooling the steering oil flowing through tubes in the oil cooler (14).
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. An improved cooling system for a hydraulic power steering system,
comprising:
a reservoir configured for storage of hydraulic steering oil;
a power steering pump configured for receiving the steering oil from said reservoir and pumping or pressurizing the steering oil;
a steering gear box for transmitting power to turn a plurality of wheels of a front axle and/or a rear axle in a vehicle; and
an oil cooler disposed in front of a radiator of the vehicle in such a manner that the steering oil from said steering gear box passes through the said oil cooler for cooling the hot steering oil.
2. The cooling system as claimed in claim 1, wherein said oil cooler returns back the steering oil to the said reservoir after cooling it.
3. The cooling system as claimed in claim 1, wherein said oil cooler is fitted in a hydraulic circuit, particularly in a predefined orientation at a suitable location in the
vehicle.
4. The cooling system as claimed in claim 1, wherein said oil cooler cools the steering oil from the said steering gear box by air and/or fluid.
5. The cooling system as claimed in claim 1, wherein said oil cooler is selected from a list of parallel flow type oil cooler, vertical parallel flow type oil cooler, single tube type oil cooler, cross flow type oil cooler and combination of two or more types.
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