Title of Invention

A TYRE PRESSURE ADJUSTMENT SYSTEM

Abstract

An automated central tyre pressure adjustment system comprising an air source for providing pressurized air, a pressure regulator with relief provision, a directional control valve with selectable operating modes, pneumatic lines interconnecting between among said system elements, an air circuit for connecting the said directional valve to each tyre chamber wherein said direction control valve having first, second and third selectable operating modes corresponding to off mode, inflation/deflation of front axle tyres and inflation/deflation of rear axle tyres respectively.

Full Text

FORM 2 THE PATENTS ACT 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See Section 10; rule 13) TITLE OF THE INVENTION Automated Central Tyre Pressure Adjustment System 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 Pandharinath Namdeo Khatmode, K. Thangaraj and S.K. Agarwal all Indian nationals of TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed. FIELD OF THE INVENTION This invention relates to system for adjusting tyre pressure in automobile while it is at rest and/or on move. This invention basically relates to manually operated tyre pressure adjustment system. BACKGROUND OF INVENTION Tyre pressure adjustment system or Central tyre inflation system briefly referred as CTIS is a well-established system mostly in army vehicles and trailer applications. Majority of the prior inventions related to tyre inflation / deflation systems make use of solenoid operated valves to control pneumatic flow. Also these systems need electronic pressure sensors, electronic logic control system to compare measured tyre pressure and control flow of air to different tyres to adjust pressure to desired value. This invites higher system cost, which is main hindrance for implementation of such a system for all commercial vehicles. Use of electrical and/or electronic systems also calls for reliability risk and complicated electrical and pneumatic circuitry. Following inventions disclose tyre pressure adjustment systems of the background interest to the present invention. A. United States Patent nos.: 4,641,698; 2,634,782; 4,782,878; 5,587,698; 6,098,682; 6,336,481 Bl; 2006/0,180,256 A1 B. European Patents: EP0 164 917; WO 2007/035975 Al Automated central tyre pressure adjustment system described in US 4,641,698 calls for additional set of check valves, which receive pilot signal from separate pneumatic line with shuttle valves. This invention deploys two three mode valves in which one valve having inflate, deflate, off mode whereas other valve having front tyre select, rear tyre select and off modes. This results in additional system cost and complex pneumatic circuit. Another invention US 2,634,782 requires separate deflation valves in addition to inflation valves to be mounted on vehicle wheels causing complex pneumatic circuit at wheel end. Also the flexibility to adjust different tyre pressures in tyres of different axles is not there. Further some inventions do not isolate rotary joints and pneumatic lines from tyres. This causes reduced life of rotary joint, leakage of air thus increasing duty cycle of compressor. OBJECTS OF INVENTION The object of the present invention is to provide an automated central tyre pressure adjustment system comprising an air source for providing pressurized air, a pressure regulator with relief provision, a directional control valve with selectable operating modes, pneumatic lines interconnecting between among said system elements, an air circuit for connecting the said directional valve to each tyre chamber wherein said direction control valve having first, second and third selectable operating modes corresponding to off mode, inflation/deflation of front axle tyres and inflation/deflation of rear axle tyres respectively. Another object of the present invention is to provide an automated central tyre pressure adjustment system comprising an air source for providing pressurized air, a pressure regulator with relief provision, a directional control valve with selectable operating modes, pneumatic lines interconnecting between among said system elements, an air circuit for connecting the said directional valve to each tyre chamber wherein said direction control valve having first, second and third selectable operating modes corresponding to off mode, inflation/deflation of front axle tyres and inflation/deflation of rear axle tyres respectively and said air circuit having a pilot operated check valve for isolating tyre from pneumatic circuit. Summary of the invention In the present invention, attempt is made to minimize or eliminate the drawbacks of the prior inventions. This is achieved by the use of all manually operated pneumatic valves. Also minimum valves are used to achieve inflation / deflation of tyres by using same pneumatic unit for two different purposes. Pilot operated check valves mounted on wheel ensure that each tyre is isolated from rotary joint and rest of the pneumatic circuit, thus ensuring minimum leakage and better life of rotary joint seals. As electrical signal is not used, need for black out provision typically required for all military applications is eliminated. Also reliability of the overall system improves. As the proposed system will be used by the driver only whenever there is terrain change, loading change or there is certain leakage in the particular tyre for short duration only. This considerably reduces duty cycle of the air compressor, thus improving its life considerably. Also pneumatic circuitry of the current invention always ensures primary importance to supply air with minimum predetermined pressure to the brake circuit required for its proper functioning. Proposed invention enables driver to set different tyre pressure for front and rear axles depending upon load reaction. Driver can fill air in front axle tyres or rear axle tyres separately. DETAILS OF DRAWINGS Figure 1 is the schematic arrangement of the pneumatic components of manually operated central tyre pressure adjustment system. DETAILED DESCRIPTION OF INVENTION Referring now to the drawing 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. The pneumatic circuit for implementing the manually operated central tyre pressure adjustment system for a four-wheeled vehicle is illustrated in figure 1. Circuit symbols are chosen as per JIS standard. Pressurized air is generated with the help of air compressor (1) mounted on and driven by vehicle engine. Air from compressor (1) goes to Air preparation unit (3) through pneumatic connection represented by (2). Air preparation unit (3) consists of air drier and purge tank. This processed air goes to system protection valve (5) also known as priority valve. This valve (5) has got four ports represented by (6), (7), (8) and (9). Ports (6), (7) and (8) supply air to front axle brakes (not shown), rear axle brakes (not shown) and parking brakes (not shown) respectively. Port (9) gives air to auxiliary systems fitted on the vehicle. The construction of system protection valve is such that if the pressure in the pneumatic lines connecting to port (6), (7) and (8) drops below minimum required set pressure for operating brake circuit, it automatically cuts off supply to auxiliary port (9); thus always giving preference to brake circuit. In case of rupture of pneumatic lines of tyre inflation system, system protection valve (5) insures that air pressure in brake circuit will not drop below certain limit to ensure safety of the vehicle and cuts off supply to tyre inflation system. Pressurized air to charge tyres is tapped from auxiliary air tank (11) fitted on vehicle chassis, which receives air from port (9) of system protection valve through pneumatic line (10). The supply air pressure is equal to the maximum system pressure available for vehicle pneumatic system. Also continuous air supply can be taken from vehicle air compressor (1), which is driven by vehicle engine represented by shaft, when other pneumatic systems connected to port (6), (7) and (8) are not operating. This pressurized air supply is given to pressure regulator (13), which is having feedback provision (14). This pressure regulator (13) can provide output air pressure from zero bar to maximum system pressure with any pressure values in between. Different pressure values can be set manually by rotating a knob (15) on pressure regulator (13). Pressure regulator (13) has got a pressure gauge (not shown) to indicate the set pressure value. Also this regulator (13) has got pressure relief provision (16), which releases any excess pressure that is available in output line (17) over the set pressure. Air supply with regulated pressure is the given to inlet port (19) of four port three position manually operated direction control valve with centre exhaust (18) through pneumatic line (17). Valve (18) comprises of four ports viz. inlet port (19), exhaust port (20) which vents to atmosphere, two output ports (21) and (22). Further valve (18) has got three modes viz. mode I, mode II and mode III. Mode I corresponds to the off mode where all output ports (21) and (22) are connected to atmosphere. Mode II corresponds to inflation / deflation of front axle tyres represented by (41a); where as Mode III corresponds to inflation / deflation of rear axle tyres represented by (41b). This direction control valve is located near to the driver generally on dashboard (not shown) or at some other location, which is easily accessible. Mode selection of this valve is done by driver by positioning the lever (35) into one of three positions I, II, III indicated by sticker pasted near lever (not shown). Air connection from ports (21) and (22) is given to front axle tyres (41a) and rear axle tyres (41b) respectively. Suitable tapping (25a) is taken from pneumatic line (23a) going to front axle tyres by providing suitable "F connector indicated by (24). From T' connector connection (25a) is given to pressure gauge (26a), which is mounted near to driver. This pressure gauge (26a) indicates the pressure in output line (23a), which in turn is pressure in front axle tyres (41a). Similar arrangement is made in pneumatic line (23b) going to rear axle tyres (41b) also. Pressure gauge (26b) for rear axle tyres (41b) is fitted beside the gauge (26a) for front axle tyres (41a). After pressure gauge (26a), air connection (27a) going to front axle is splited into two lines (29a) with 'T' connector (28); one going to right wheel tyre (41a) and other going to left wheel tyre (41a). On each wheel there is a rotary fitting represented by (30a and 30b); mounted on wheel hub (not shown). This rotary fitting is having one end with stud (32a), which is mounted on a bracket (not shown), which in turn is mounted with the help of wheel bolts onto the wheel. This bracket rotates with the wheel. Input air connection is given to the other port (31a) of rotary joint (30a) which will be held stationary with the help of flexible pneumatic connection (29a). From stud end (32a) of the rotary joint (30a), air connection (33a) is given to the pilot operated check valve (34a). This valve (34a) comprises of one inlet port (36a), one pilot port (37a) and one output port (38a). For this valve (34a); pilot signal is tapped from input line (33a) itself. This valve (34a) is normally closed valve. As soon as there is input signal pressure above the crack pressure required to open (34a) in input line (33a), (34a) will open and allow flow of air from input line (33a) to output line (39a) and vice versa depending on the pressure differential. This valve (34a) is basically used to cut off all individual wheels from rest of the pneumatic line whenever inflation / deflation are not underway. This helps to keep all rotary joints and pneumatic lines un-pressurized whenever tyre pressure adjustments are not underway. Due to this air leakage in the system gets minimized. Also the life of rotary joints gets increased substantially. From check valve (34a) connection (39a) is given to the wheel valve (40a), which discharges air to the closed chamber formed by tyre and wheel rim or tube fitted inside tyre. For rear tyres (41b) another pneumatic line (23b) is taken from port (22) of direction control valve (18). After line (23b), pneumatic fitments are identical to the fitments done for line going to front axle tyres. SYSTEM OPERATION Operation of automated central tyre pressure adjustment system for a four-wheeled vehicle can be best described in two scenario's viz. inflation and deflation of tyre to desired pressure. A) Tyre inflation cycle With the help of knob (15) on pressure regulator (13) driver sets required air pressure for front axle tyres (41a) based on the terrain or load. This gives pressurized air of desired pressure value to port (19) of direction control valve (18). Initially valve (18) is in mode I. In this mode I of valve (18), downstream ports (21) and (22) are in direct communication with upstream port (20), which is directly vented to atmosphere. This ensures that both pneumatic lines going to front axle tyres (41a) and rear axle tyres (41b) are not under pressure whenever there is no pressure adjustment underway. When driver puts valve (18) in mode II, upstream port (19) is in direct communication with downstream port (21). Thus air with pressure set by driver passes through line (23a) - (27a) - (29a) - rotary joint (30a) - (33a) to the pilot operated check valve (34a). At the same time pressurized air passes the inlet port (37a) of valve (34a). If the input signal in pilot line (37a) is above the cracking pressure, valve (34a) opens and upstream port (36a) is in direct communication with downstream port (38a). Pressurized air passes through line (39a) to wheel valve (40a), which in turn delivers it into the space between tyre and wheel rim or tube represented by (41a). As the air starts flowing into the tyres (41a), pressure gauge (26a) displays the pressure available on downstream side of valve (18). As soon as the pressure in both front axle tyres (41a) reaches desired value set by driver, pressure gauge (26a) will show a steady pressure reading equal the set pressure displayed on gauge of the regulator. By noticing this, driver will shift lever (35) of valve (18) into mode I. This connects port (21) directly to port (20) and closes inlet port (19). Thus line (23a) is directly vented to atmosphere, creating a sudden pressure drop and flow reversal happens in the pneumatic line (29a). Due to this momentarily vacuum is created on the input side of pilot line (37a) of valve (34a). This causes sudden closure of valve (34a). Thus front tyres 41a are isolated from rest of the pneumatic circuit. Now, driver sets a desired pressure for rear axle tyres with the help of knob (15) of the pressure regulator (13). Then he shifts lever (35) of valve (18) into mode III position. Again the same events as described for inflation of front axle tyres happen in the pneumatic line (23b) going to rear axle tyres (41b). In this case, driver monitors tyre pressure for rear axle tyres with the pressure gauge (26b). As soon as pressure in rear tyres reaches set value, driver puts valve (18) in mode I with the help of lever (35). As line (23b) is vented to atmosphere; valves (34b) on rear axle wheels (41b) gets closed, thus isolating tyres (41b) from rest of pneumatic circuit. Now driver rotates knob (15) of regulator (14) to zero value. This ensures all pneumatic components from regulator to inlet port of check valve are not under pressure. This completes inflation cycle for all tyres. B) Tyre deflation cycle Due to change in terrain or loading on the vehicle driver needs to reduce the tyre pressure. For this driver sets desired pressure for front axle tyres with the help of regulator knob (15). Then driver puts valve (18) in mode II, which sends pressurized air to pneumatic line (23a). Pressurized air reaches input port of valve (34a) through pneumatic line as described in tyre inflation cycle. As the air pressure in the pilot port (37a) is above crack pressure of valve (34a), these valves are opened. As the pressure in the tyres (41a) is more than the set pressure, air starts flowing from tyre to regulator (13). As soon as regulator (13) receives feedback signal through feedback port (14), it compares the set pressure value and the pressure on the downstream side. As the pressure on downstream side is more than the set pressure, it opens relief port (16). Now, the air from tyres is vented slowly to atmosphere until the pressure value indicated by gauge (26a) reaches the set pressure value. As soon as gauge (26a) shows set pressure value, driver shifts knob .(35) to mode I. Thus pneumatic line (23a) connecting to front axle tyres (41a) are vented to atmosphere. This causes momentarily vacuum in the pilot lines (37a) of valves (34a) causing their closure. Due to this tyre (41a) gets isolated from rest of the pneumatic circuit. Now, driver sets a desired pressure for rear axle tyres with the help of knob (15) of the pressure regulator (13). Then he shifts lever (35) of valve (18) into mode III position. Again the same events as described for deflation of front axle tyres (41a) happen in the pneumatic line (23b) going to rear axle tyres (41b). In this case, driver monitors tyre pressure for rear axle tyres (41b) with the pressure gauge (26b). As soon as pressure in rear tyres (41b) reaches set value, driver puts valve (18) in mode I with the help of lever (35). As line (23b) is vented to atmosphere; valves (34b) gets closed, thus isolating tyres (41b) from rest of pneumatic circuit. Now driver rotates knob (15) of regulator (14) to zero value. This ensures all pneumatic components from regulator to inlet port of check valve are not under pressure. This completes deflation cycle for all tyres. ADVANTAGES Minimum valves are used to achieve inflation / deflation of tyres by using same pneumatic unit for two different purposes. Pilot operated check valves mounted on wheel ensure that each tyre is isolated from rotary joint and rest of the pneumatic circuit, thus ensuring minimum leakage and better life of rotary joint seals. As electrical signal is not used, need for black out provision typically required for all military applications is eliminated. Also reliability of the overall system improves. As the proposed system will be used by the driver only whenever there is terrain change, loading change or there is certain leakage in the particular tyre for short duration only. This considerably reduces duty cycle of the air compressor, thus improving its life considerably. Also pneumatic circuitry of the current invention always ensures primary importance to supply air with minimum predetermined pressure to the brake circuit required for its proper functioning. It enables driver to set different tyre pressure for front and rear axles depending upon load reaction. Driver can fill air in front axle tyres or rear axle tyres separately. 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. WE CLAIM 1. An automated central tyre pressure adjustment system comprising an air source for providing pressurized air, a pressure regulator with relief provision, a directional control valve with selectable operating modes, pneumatic lines interconnecting between among said system elements, an air circuit for connecting the said directional valve to each tyre chamber wherein said direction control valve having first, second and third selectable operating modes corresponding to off mode, inflation/deflation of front axle tyres and inflation/deflation of rear axle tyres respectively. 2. An automated central tyre pressure adjustment system as claimed in claim 1 wherein said pressure regulator having a mechanism for setting different down stream pressure. 3. An automated central tyre pressure adjustment system as claimed in claim 1 wherein said pressure regulator having a feedback provision for sensing down stream pressure, and a pressure relief provision for releasing excess pressure to achieve set down stream pressure value. 4. An automated central tyre pressure adjustment system as claimed in claim 1 wherein said air circuits having a rotary joint for air passage between rotating tyre and pneumatic lines and a pilot operated check valve for isolating tyre from pneumatic circuit. 5. An automated central tyre pressure adjustment system as claimed in claim 1 wherein said directional control valve having a inlet port, an exhaust port vented to atmosphere and two output ports each connected to front and rear axle tyres. 6. An automated central tyre pressure adjustment system as claimed in claim 1 wherein said air circuit having a pressure gauge for observing the air pressure in tyres. 7. An automated central tyre pressure adjustment system as claimed in claim 1 wherein an air processing unit is incorporated between said air source and pressure regulator. 8. An automated central tyre pressure adjustment system as claimed in claim 7 wherein a system protection valve (priority valve) is incorporated between said air processing unit and pressure regulator. 9. An automated central tyre pressure adjustment system comprising an air source for providing pressurized air, a pressure regulator with relief provision, a directional control valve with selectable operating modes, pneumatic lines interconnecting between among said system elements, an air circuit for connecting the said directional valve to each tyre chamber wherein said direction control valve having first, second and third selectable operating modes corresponding to off mode, inflation/deflation of front axle tyres and inflation/deflation of rear axle tyres respectively and said air circuit having a pilot operated check valve for isolating tyre from pneumatic circuit. 10. An automated central tyre pressure adjustment system substantially as herein described with reference to accompanying drawings ABSTRACT Automated Central Tyre Pressure Adjustment System An automated central tyre pressure adjustment system comprising an air source for providing pressurized air, a pressure regulator with relief provision, a directional control valve with selectable operating modes, pneumatic lines interconnecting between among said system elements, an air circuit for connecting the said directional valve to each tyre chamber wherein said direction control valve having first, second and third selectable operating modes corresponding to off mode, inflation/deflation of front axle tyres and inflation/deflation of rear axle tyres respectively. Fie 1.

Documents:

1981-MUM-2007-ABSTRACT(31-1-2012).pdf

1981-mum-2007-abstract.doc

1981-mum-2007-abstract.pdf

1981-MUM-2007-CLAIMS(AMENDED)-(15-4-2013).pdf

1981-MUM-2007-CLAIMS(AMENDED)-(31-1-2012).pdf

1981-mum-2007-claims.doc

1981-mum-2007-claims.pdf

1981-MUM-2007-CORRESPONDENCE(21-11-2007).pdf

1981-MUM-2007-CORRESPONDENCE(24-12-2012).pdf

1981-mum-2007-correspondence-received.pdf

1981-mum-2007-description (complete).pdf

1981-MUM-2007-DRAWING(31-1-2012).pdf

1981-mum-2007-drawings.pdf

1981-MUM-2007-FORM 1(15-4-2013).pdf

1981-MUM-2007-FORM 13(15-4-2013).pdf

1981-MUM-2007-FORM 13(31-1-2012).pdf

1981-MUM-2007-FORM 18(21-11-2007).pdf

1981-MUM-2007-FORM 2(TITLE PAGE)-(15-4-2013).pdf

1981-MUM-2007-FORM 8(21-11-2007).pdf

1981-MUM-2007-FORM 9(21-11-2007).pdf

1981-mum-2007-form-1.pdf

1981-mum-2007-form-2.doc

1981-mum-2007-form-2.pdf

1981-mum-2007-form-26.pdf

1981-mum-2007-form-3.pdf

1981-MUM-2007-GENERAL POWER OF ATTORNEY(31-1-2012).pdf

1981-MUM-2007-MARKED COPY(15-4-2013).pdf

1981-MUM-2007-MARKED COPY(31-1-2012).pdf

1981-MUM-2007-REPLY TO EXAMINATION REPORT(31-1-2012).pdf

1981-MUM-2007-REPLY TO HEARING(15-4-2013).pdf

1981-MUM-2007-SPECIFICATION(AMENDED)-(15-4-2013).pdf

1981-MUM-2007-SPECIFICATION(AMENDED)-(31-1-2012).pdf

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