DESC:TECHINCAL FIELD

Embodiments of the present disclosure relates to steering system for a vehicle, more particularly embodiments relates to a pneumatically operated hydraulic power steering system of the vehicle.

BACKGROUND OF DISCLOSURE

Presently, the vehicles are provided with center-closed hydraulic power steering system with a conventional mechanical drive-train for reducing the steering effort by the driver. The power steering system includes a hydraulic pump mechanically driven by engine, a steering gear box fluidly connected to the pump and the steering gear box connected to a driver operated steering wheel through steering column. In the power steering system, the pump is driven by engine, so when the engine is in off condition the pump does not get any feed from the engine and hence the power steering system will not work while the engine is in off condition. Therefore, handling of steering in the engine off condition will become very difficult. Further, in the conventional hydraulic power steering systems the only means to supply hydraulic fluid to the steering gear box is hydraulic pump, so in case any pump failure power steering system does not work. Again, in such situations handling of steering becomes very difficult. In addition, the use of hydraulic pump in the power steering system increases the fuel consumption in the vehicle, since the hydraulic pump is coupled to the engine and it takes the power continuously from the engine.

One way of operating the power steering system in engine off condition is by providing hydraulic accumulator. For example U.S. Patent Application No.11/999,884 describes the use of accumulator which stores the hydraulic fluid under pressure when the hydraulic pump is operating and releases the same to operate the power steering in engine off condition. In this example the accumulator can operate the hydraulic power steering system only when the pressurized hydraulic fluid is present in the accumulator. Hence, the usage accumulator to operate the power steering to tow the vehicle for long distance is not possible.

In light of forgoing discussion, it is necessary to develop a pneumatically operated hydraulic power steering system which continuously operates the hydraulic power steering system of the vehicle in the emergency condition i.e. engine is in off condition and in the hydraulic pump failure condition to reduce the effort of driver to steer the vehicle.

SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a system and method as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the preset disclosure there is provided a pneumatically operated hydraulic power steering system for a vehicle. The system comprises an air compressor connectable to an engine of the vehicle, an air tank fluidly connected to the air compressor for storing compressed air, and a spring loaded piston cylinder arrangement provided in between outlet of the air tank and a power steering control valve of the steering gear box. The spring loaded piston cylinder arrangement is configured into an air compartment and a hydraulic compartment arranged one above the other respectively. An inlet of the air compartment of the spring loaded piston cylinder arrangement is fluidly connected to the compressed air tank for receiving the compressed air, and an outlet of the hydraulic compartment of the spring loaded piston cylinder arrangement is fluidly connected to the power steering control valve of the steering gear box for delivering hydraulic fluid into the steering gear box.

In an embodiment of the present disclosure, un-loader valve is provided in an air flow line connected between the air compressor and the air tank.

In an embodiment of the present disclosure, a solenoid valve provided in an airflow line connected between the air tank and the inlet of the air compartment for regulating flow of compressed air from the air tank into the air compartment.

In an embodiment of the present disclosure, at least one non-return valve is provided in a hydraulic fluid flow line connected between the outlet of the hydraulic compartment and the power steering control valve of the steering gear box to prevent flow of the hydraulic fluid from the steering gear box to the hydraulic compartment. Further, a pressure regulator provided in a hydraulic fluid flow line connected between the outlet of the hydraulic compartment and the power steering control valve of the steering gear box to regulate pressure of the hydraulic fluid.

In an embodiment of the present disclosure, an inlet of the hydraulic compartment is fluidly connected to a hydraulic reservoir, and an outlet of the steering gear box is fluidly connected to the hydraulic reservoir.

In an embodiment of the present disclosure, the air compartment is above the piston and the hydraulic compartment is formed below the piston in the spring loaded piston cylinder arrangement.

In an embodiment of the present disclosure, the system further comprises a hydraulic pump coupled to the engine of the vehicle, wherein an inlet of the hydraulic pump is fluidly connected to a hydraulic reservoir, and an outlet of the hydraulic pump is fluidly connected to the power steering control valve of the steering gear box. Further, a solenoid valve provided in a fluid line between the air tank and a spring loaded piston cylinder arrangement is activated when atleast one of the hydraulic pump fails in the system or when the engine is in off condition.

Another non-limiting embodiment of the present disclosure provides for a method for operating a pneumatically operated hydraulic power steering system of the vehicle. The method comprising acts of: actuating a solenoid valve provided in a fluid line between an air tank and a spring loaded piston cylinder arrangement for regulating flow of compressed air from the air tank into an air compartment of the spring loaded piston cylinder arrangement, wherein the compressed air moves the piston inside the cylinder, and pressurizes hydraulic fluid present in a hydraulic compartment of the spring loaded piston cylinder arrangement; and passing the pressurized hydraulic fluid into a steering gear box for operating the hydraulic power steering system.

In an embodiment of the present disclosure, the solenoid valve is regulated automatically or manually.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

OBJECTIVES OF THE DISCLOSURE

One object of the present disclosure is to provide a pneumatically operated hydraulic power steering system which operates the hydraulic power steering system when engine is in off condition.

One object of the present disclosure is to provide a pneumatically operated hydraulic power steering system which operates the hydraulic power steering system in hydraulic pump failure condition.

One object of the present disclosure is to provide a pneumatically operated hydraulic power steering system which is simple in construction and easy to assemble.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 illustrates a schematic view of a pneumatically operated hydraulic power steering system according to present disclosure.

FIG. 2 illustrates a schematic view of a conventional hydraulic power steering system with a pneumatically operated hydraulic power steering system of present disclosure.

FIG. 3 illustrates sectional view of steering gear box.

FIG. 4 illustrates working principle of the power steering control valve.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

To overcome the drawbacks mentioned in the background, a pneumatically operated hydraulic power steering system (A) to steer the vehicle is disclosed. The system (A) continuously operates the hydraulic power steering system of the vehicle in the emergency condition i.e. engine is in off condition and in the hydraulic pump failure condition to reduce the effort of driver. This improves the driver comfort in the vehicle.

In present invention compressed air coming from the compressor (1) is stored in the air tank (5), here one un-loader valve (4) is used for maintaining the pressure of compressed air in the air tank (5), during emergency condition i.e. in engine off condition and in hydraulic pump failure condition a solenoid valve (6) will be activated to open the outlet (5b) of air tank (5). After opening the outlet (5b) of the air tank (5) compressed air will act on piston (7a) of spring loaded piston cylinder arrangement (7). Since air compartment (7c) of the spring loaded piston cylinder arrangement (7) will be filled with air and other side i.e. hydraulic compartment (7d) is filled with hydraulic fluid coming from reservoir (3), so the compressed air push the piston (7a) of cylinder and then hydraulic fluid in hydraulic compartment (7d) gets pressurized, since the cross section of cylinder at hydraulic compartment (7d) is less as compare to diameter of piston (7a), so hydraulic fluid coming out from the cylinder will be highly pressurized. Now this pressurized fluid will be passed to the steering gear box (8) with the help of hydraulic fluid flow line (11b) to operate the hydraulic power steering system.

For commercially acceptable steering control characteristics, in the fuel efficient power steering system (A) of the present disclosure, a non-return valve (14) and a pressure regulatory valve (15) are provided. The non-return valve (14) and the pressure regulatory valve (15) are configured in the hydraulic fluid flow line (11b) in accordance with a preferred embodiment of the invention in order to meter the flow of pressurized fluid from the spring loaded piston cylinder arrangement (7) to the steering gear box (8). The non-return valve (14) and the pressure regulatory valve (15) allow the flow of pressurized fluid in the right relationship to the extent of rotational force applied to the steering wheel (10), for better drivability and a natural-feeling steering response. In steering gear box (8) if a torque is transmitted to the worm (8d) from the steering wheel (10) or the steered wheels, a relative rotary motion influenced by the torsion bar (9) will occur between the power steering control valve (8a) of the steering gear box. The power steering control valve (8a) is thereby caused to change its position in relation to the worm (8d) surrounding it. Pressurized hydraulic fluid coming from the spring loaded piton cylinder arrangement (7) will now flow through connecting bores (8b and 8c) to one of the two power cylinder chambers and assists the axial movement of the piston (8h). When the steering wheel (10) is released and no any further turning is required the action of the twisted torsion bar (9) makes the hydraulic fluid to bypass from outlet (8d) of the steering gear box (8) to the reservoir (3).

As an exemplary embodiment of the present disclosure FIG. 1 illustrates a schematic view of a pneumatically operated hydraulic power steering system (A) for a vehicle. The system comprises following components but not limited to, an air compressor (2) coupled to an engine (1) of the vehicle, and an air tank (5) fluidly connected to the compressor at inlet (5a) of the air tank (5) for storing the compressed air. A spring loaded piston cylinder arrangement (7) is provided in between the air tank (5) and a steering gear box (8) for supplying hydraulic fluid to the steering gear box (8). Further, a solenoid valve (6) is provided in an air flow line (12b) connected between an outlet (5b) of the air tank (5) and the spring loaded piston cylinder arrangement (7) for regulating the flow of compressed air from the air tank (5) to the air compartment (7c). The system (A) further comprises a non-return valve (14) in a hydraulic fluid flow line (11b) connected between the spring loaded piston cylinder arrangement (7) and the steering gear box (8) to prevent flow of the hydraulic fluid from the steering gear box (8) to the hydraulic compartment of the spring loaded piston cylinder arrangement (7). A pressure regulator (15) is provided in the hydraulic fluid flow line (11b) to regulate pressure of the hydraulic fluid entering the steering gear box (8). An outlet of hydraulic fluid flow line (11b) is connected to a power steering control valve (8a) of the steering gear box (8) to supply the hydraulic fluid to operate the hydraulic power steering system (A).

In vehicle running condition air compressor (2) which is coupled to the engine (1) will fill the air tank (5) with compressed air. An un-loader valve (4) is provided in the air flow line (12b) connected between the compressor (2) and the air tank (5) for safety purpose for avoiding excess pressure in air tank (5). Further, the solenoid valve (6) will be activated for operating the steering system. The solenoid valve (6) will open an outlet (5a) of air tank (5) so that compressed air can act on the piston (7a) of spring loaded piston cylinder arrangement (7), compressed air will be act on the air compartment (7c) region since Hydraulic compartment (7d) region is filled with hydraulic fluid coming from the reservoir (3) and the cross section area of Hydraulic compartment (7d) is very less in compare with area of air compartment (7c), thus after movement of piston (7a) due to compressed air, pressure of hydraulic fluid coming out from the spring loaded piston cylinder arrangement (7) will be increased. This pressurized fluid will now act in the steering gear box (8) after passing through hydraulic flow line (11b). A non-return valve (14) is provided in the hydraulic flow line (11b) for avoiding the returning of hydraulic fluid. Further, a pressure regulatory valve (15) is also provided in the hydraulic flow line (11b) for maintaining the pressure of hydraulic fluid.

Now when steering wheel (10) is rotated clock wise or anti clock wise, pressurized fluid after coming from pressure regulator (15) directly goes inside the steering gear box (8) through power steering control valve (8a). Operation of power steering control valve (8a) is proportionally controlled through rotation of steering wheel (10). The power steering control valve (8a) is further fluidly connected with steering gear box (8) though hydraulic flow line (11b). Power steering control valve (8a) control the flow of pressurized fluid for left hand side and right hand side turning. Pressurized hydraulic fluid can now flow through connecting bores to one of the two power cylinder chambers (8b and 8c) and assists the axial movement of the piston (8h). When the steering wheel (10) is released or in case vehicle is moving in straight ahead condition, then steering wheel (10) doesn’t activate the power steering control valve (8a) and flow of pressurized fluid will be bypass the power steering system (A). High pressurized fluid will return to reservoir (3) through hydraulic fluid flow line (11c) provided between outlet (8d) of the steering gear box (8) and the reservoir (3).

Further, after full movement of piston (7a) of cylinder inside a cylinder towards the hydraulic chamber (7d), the solenoid valve (6) will close the outlet (5b) of the air tank (5). Then compressed air will not act on the piston (7a) of spring loaded piston cylinder arrangement (7) in this condition compressed spring (7b) which is connected with the piston (7a) push the piston (7a) towards the air compartment (7c) due to the compressive energy stored in spring (7b). Thus, the piston (7a) will return to the original position. Thus, it is clear that the present disclosure provide a new provision for power steering without using any hydraulic pump driven by the engine.

Now referring to FIG.2 which illustrates a schematic view of a conventional hydraulic power steering system integrated with a pneumatically operated hydraulic power steering system (A). In the conventional hydraulic power steering system, a hydraulic pump (17) is provided which get feed from engine (1) through gear driven arrangement (16), this pump in active condition pressurize the hydraulic fluid coming from hydraulic reservoir (3), and feed the pressurised hydraulic fluid to the steering gear box (8) through hydraulic line (11d) and power steering control valve (8a) for operating the power steering. But the negative aspect of conventional hydraulic power steering system is that, the system will not function in emergency conditions. The emergency condition is selected from atleast one of engine off condition and hydraulic pump failure condition. So for solving the aforementioned problem, the pneumatically operated hydraulic steering system (A) is integrated to the conventional hydraulic steering system.

In the emergency conditions such as in engine off condition, and in hydraulic pump failure condition, the solenoid valve (6) which is provided in the air supply line (12b) is activated for supplying the compressed air from air tank (5) to the air compartment (7c) of the spring loaded piston cylinder arrangement (7). In an embodiment of the present disclosure the solenoid valve is activated by means selected from atleast one of manually and automatically. Said solenoid valve (6) is interfaced with an Electronic Control Unit (ECU) [not shown] to activate the solenoid (6) automatically.

After receiving the signal, the solenoid valve (6) will open an outlet (5a) of air tank (5) so that compressed air can act on the piston (7a) of spring loaded piston cylinder arrangement (7), compressed air will be act on the air compartment (7c), since hydraulic compartment (7d) is filled with hydraulic fluid coming from the reservoir (3) and the cross section area of hydraulic compartment (7d) is very less in compare with area of air compartment (7c) so after movement of piston (7a) due to compressed air, and the pressure of hydraulic fluid coming out from the spring loaded piston cylinder arrangement (7) will be increased. The outlet (7e) of the hydraulic compartment (7d) is fluidly connected to the power steering control valve (8a) via main hydraulic fluid flow line (11d). Hence, the pressurized hydraulic fluid from the hydraulic compartment (7c) will be passed to the steering gear box (8) for operating the hydraulic power steering system (A). Thus, the pneumatically operated hydraulic power steering system (A) of the present disclosure provides a solution for operating the hydraulic power steering system (A) in case of emergency conditions such as in engine off condition, and in hydraulic pump failure condition.

FIG. 3 is an exemplary embodiment which illustrates a sectional view of steering gear box (8). The pressurized fluid coming from hydraulic fluid flow line (11b) via pressure regulator (15) directly go inside of steering gear box (8) through power steering control valve (8a) when the steering wheel (10) is rotated by the driver in clock-wise or anti-clock wise direction. The power steering control valve (8a) is further fluidly connected with steering gear box (8) through input (8f) and return groove (8g) to pass the hydraulic fluid to either one of connecting bores (8b and 8c) to assists the axial movement of the piston (8h) to rotate wheels either to left or right. The axial movement of piston (8h) converts the rotary movement of sector shaft (18) through worm gear (8d). Then the drop arm (13) mounted on the sector shaft (18) moves the steering linkage which goes to steering arms thus causing the road wheels to be turned.

FIG. 4 is an exemplary embodiment which illustrates working principle of the power steering control valve (8a). Operation of power steering control valve (8a) is proportionally controlled through the rotation of steering wheel (10). If a torque is transmitted to the power steering control valve (8a) or the worm gear (8d) from the steering wheel (10), a relative rotary motion influenced by the torsion bar (9) will occur between the power steering control valve (8a) and the worm gear (8d). The power steering control valve (8a) is thereby caused to change its position in relation to the worm gear (8d), so that the relative position of the control grooves (8i), (8j), (8k) and (8l) are changed. Pressurized oil can now flow through connecting radial incoming groove (8m) to one of the two power cylinder chambers (8b) and (8c), to assist the axial movement of piston (8h). At the same time the sector shaft (18), which is arranged at right angles to the longitudinal axis of the piston (8h), is caused to rotate. Thus drop arm (13) mounted on the sector shaft (18) moves the steering linkage which goes to steering arm and causing to front road wheels to be turned.

When the steering wheel (10) is released i.e. no power steering required and vehicle is moving in straight ahead condition, the action of the twisted torsion bar (9) makes the power steering control valve (8a) grooves return to the neutral position, in this condition the same system pressure will exist in both of the power cylinder bores (8b and 8c). Since in this case there will be no any difference in pressure between power cylinders bores (8b and 8c) so movement of piston (8h) will be not exist and pressurized oil will be by pass through radial return groove (8g) to hydraulic reservoir (3) via return hydraulic fluid flow line (11c).

Advantages:

The present disclosure provides a pneumatically operated hydraulic power steering system which improves the fuel efficiency of the vehicle, since the hydraulic pump is eliminated.

The present disclosure provides a pneumatically operated hydraulic power steering system which operates the hydraulic power steering system in the emergency situations such as in engine is in off condition and in hydraulic pump failure condition. Hence steering effort of the driver is reduced during vehicle towing condition.

The present disclosure provides a pneumatically operated hydraulic power steering system which is simple in construction, easy to assemble and can be retro fitted on to the vehicles easily.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Referral Numerals:

Reference number Description
A Pneumatically operated hydraulic power steering system
1 Engine
2 Air compressor
3 Hydraulic reservoir
4 Un-loader valve
5 Air tank
5a and 5b Inlet and outlet of the air tank
6 Solenoid valve
7 Spring actuated piston cylinder arrangement
7a Piston
7b Spring
7c Air compartment
7d Hydraulic compartment
7e Outlet of hydraulic compartment
7f Inlet of air compartment
8 Steering gear box
8a Power steering control valve
8b and 8c Cylinder bores
8d Worm gear
8e Outlet of the steering gear box
8f Incoming groove
8g Return groove
8h Axial piston
8i,8j, 8l, 8m Grooves in the steering gear box
8n Groove in the steering gear box
9 Torsion bar
10 Steering wheel
11a Hydraulic fluid flow line connected between the hydraulic reservoir and inlet of the cylinder
11b Hydraulic fluid flow line connected between the hydraulic reservoir and inlet of the power steering control valve in the steering gear box
11c Hydraulic fluid flow line connected between reservoir and steering gear box
11d Hydraulic fluid flow line connected between hydraulic pump and steering gear box
12a Air flow line connected between air compressor and the air tank
12b Air flow line connected between air the air tank and the piston cylinder arrangement
13 Drop arm
14 Non return valve
15 Pressure regulator
16 Gear
17 Hydraulic pump
17a and 17b Inlet and outlet of the hydraulic pump
18 Sector shaft

,CLAIMS:1. A pneumatically operated hydraulic power steering system (A) for a vehicle, said system (A) comprising:
an air compressor (2) connectable to an engine (1) of the vehicle;
an air tank (5) for storing compressed air, wherein inlet (5a) of the air tank is fluidly connected to the air compressor (2);
a spring loaded piston cylinder arrangement (7) provided in between outlet (5b) of the air tank (5) and a power steering control valve (8a) of the steering gear box (8), wherein the spring loaded piston cylinder arrangement (7) is configured into an air compartment (7c) and a hydraulic compartment (7d) arranged one above the other respectively;
wherein, an inlet (7f) of the air compartment (7c) of the spring loaded piston cylinder arrangement (7) is fluidly connected to the compressed air tank (5) for receiving the compressed air, and an outlet (7e) of the hydraulic compartment (7d) of the spring loaded piston cylinder arrangement (7) is fluidly connected to the power steering control valve (8a) of the steering gear box (8) for delivering hydraulic fluid into the steering gear box (8).

2. The system as claimed in claim 1 comprises an un-loader valve (4) provided in an air flow line (12a) connected between the air compressor (2) and the air tank (5).

3. The system as claimed in claim 1 comprises a solenoid valve (6) provided in airflow line (12b) connected between the air tank (5) and the inlet (7f) of the air compartment (7c) for regulating flow of compressed air from the air tank (5) into the air compartment (7c).

4. The system as claimed in claim 1 comprises at least one non-return valve (14) provided in a hydraulic fluid flow line (11b) connected between the outlet (7e) of the hydraulic compartment (7d) and the power steering control valve (8a) of the steering gear box (8) to prevent flow of the hydraulic fluid from the steering gear box (8) to the hydraulic compartment (7d).

5. The system as claimed in claim 1 comprises a pressure regulator (15) provided in a hydraulic fluid flow line (11b) connected between the outlet (7e) of the hydraulic compartment (7d) and the power steering control valve (8a) of the steering gear box (8) to regulate pressure of the hydraulic fluid.

6. The system as claimed in claim 1, wherein an inlet (7g) of the hydraulic compartment (7d) is fluidly connected to a hydraulic reservoir (3).

7. The system as claimed in claim 1, wherein an outlet (8e) of the steering gear box (8) is fluidly connected to the hydraulic reservoir (3).

8. The system as claimed in claim 1, wherein the air compartment (7c) is above the piston (7a) and the hydraulic compartment (7d) is formed below the piston (7a) in the spring loaded piston cylinder arrangement (7).

9. The system as claimed in claim 1 further comprises a hydraulic pump (17) coupled to an engine (1) of the vehicle, wherein an inlet (17a) of the hydraulic pump (17) is fluidly connected to a hydraulic reservoir (3), and an outlet (17b) of the hydraulic pump (17) is fluidly connected to the power steering control valve (8a) of the steering gear box (8).

10. The system as claimed in claim 9, wherein a solenoid valve (6) provided in a fluid line (12b) between the air tank (5) and a spring loaded piston cylinder arrangement (7) is activated when atleast one of the hydraulic pump (17) fails in the system (A) or when the engine (1) is in off condition.

11. A method for operating a pneumatically operated hydraulic power steering system (A) of a vehicle, said method comprising act of:
actuating a solenoid valve (6) provided in a fluid line (12b) between an air tank (5) and a spring loaded piston cylinder arrangement (7) for regulating flow of compressed air from the air tank (5) into an air compartment (7c) of the spring loaded piston cylinder arrangement (7), wherein the compressed air moves the piston (7a) inside the cylinder, and pressurizes hydraulic fluid present in a hydraulic compartment (7d) of the spring loaded piston cylinder arrangement (7); and
passing the pressurized hydraulic fluid into a steering gear box (8) for operating the hydraulic power steering system (A).

12. The method as claimed in claim 11, wherein the solenoid valve (6) is regulated automatically or manually.

13. The method as claimed in claim 11, wherein the solenoid valve (6) is activated when atleast one of the hydraulic pump (17) fails in the system (A) or when the engine (1) is in off condition.

14. A vehicle comprising a pneumatically operated hydraulic power steering system as claimed in claim 1.