FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Foolproof System For Warning Of Low Level Of Hydraulic Fluid For Automobile
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
Mr. Anshuman Gupta, Mr.Bisen Badal, both 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 INVENTION
This invention relates to automobile brake and accelerator systems and more particularly it relates to foolproof fluid level warning system for automobiles.
BACKGROUND OF THE INVENTION
Automobiles having hydraulic brake systems are provided with brake fluid reservoir with FLWI (Fluid Level Warning Indicator) to reduce the chances of accidents due to NO brake fluid available for braking. FLWI gives visual and, in some vehicles, audio warning to the driver if fluid level dips below a specified level. The conventional hydraulic brake fluid reservoir consists of a float, one electric terminal fitted at bottom of float and another electric terminal fitted inside at the bottom of reservoir. Position of float will change based on the level of fluid inside the reservoir. When the fluid level goes below the prescribed safe level the electric terminal fitted to float comes in contact with electric terminal fitted to reservoir, because of which the electric circuit gets completed and due to which warning signal gets activated.
The drawback associated with this system is it gives only a warning to the driver, which may be some time overlooked by him since automobile will continue to behave normal for some time even after warning. But after some distance there are very high chances that there will be NO brakes to stop the automobile due to lack of hydraulic brake fluid inside the reservoir, this can lead to fatal accidents.
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OBJECTS OF INVENTION
The main object of this invention is to provide a foolproof fluid level warning system for automobiles.
Yet another object of this invention is to provide a foolproof fluid level warning system with audio and/or visual warning indicators for automobiles. Yet another object of this invention is to provide a foolproof fluid level warning system with over-ride switch for towing the automobile at minimum speed.
Yet another object of this invention is to provide a foolproof fluid level warning system for automobiles, which is simple in construction and cost ineffective.
BRIEF DESCRIPTION OF INVENTION
Foolproof fluid level warning system in accordance with this invention basically comprises of constraining mechanism, override switch and relay wherein constraining mechanism is connected to relay to actuate constraining mechanism. Relay used in this system is having an interface of battery, fluid reservoir with FLWI and an electromagnetic device with spring of constraining mechanism. Current from battery will flow to electromagnetic device with spring only when FLWI is active i.e. when fluid level is low. The electromagnetic device with spring will get energized and compresses when current flows through it, which in turn restrict the movement of accelerator pedal by pulling the constraining sleeve. An override switch is provided in the system as a safety measure to give some degree of freedom to accelerator pedal when required.
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This invention aims at providing a foolproof driver intervention system that will constrain the motion of accelerator linkages, ultimately leading to automobile halt during low level of brake fluid in the hydraulic brake circuit. When FLWI is inactive, relay doesn't allow the current to flow from battery to electromagnetic spring, hence accelerator operates normally. But when FLWI becomes active due to low fluid level, an input signal is given to the relay and current starts to flow from battery to electromagnetic spring. The inward movement (i.e. towards the pedal) of linkage constrains the only available degree of freedom of the accelerator pedal. Hence with low fluid level in reservoir, automobile can't be accelerated to any speed. An override switch helps temporarily to drive the automobile but at very slow speed. This switch reduces the current flowing to the electromagnetic device and hence constraining sleeve retracts to a small distance giving accelerator pedal some space to operate but only to a certain level. This mechanism will help in towing of automobile.
This invention aims at developing a mechanism that would actively interfere the driver in case of low fluid level by directly controlling the accelerator pedal, which is common component for all types of automobiles driven by any type of fuel.
DESCRIPTION OF THE PREFERRED EMBODIMENTS 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,
Fig. 1 shows a layout of low fluid warning system
Fig. 2(a) shows constraining mechanism used in the system in de-energized state
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Fig. 2(b) shows constraining mechanism used in the system in energized state
when fluid level dips below prescribed level
Fig. 2(c) shows constraining mechanism used in the system in partially
energized state when over-ride switch is activated
Fig. 3 shows constraining mechanism connected with accelerator pedal
Now referring to figs. 1 to 3, foolproof fluid level warning system in accordance with this invention basically comprises of constraining mechanism (4), override switch (6) and relay (2) wherein constraining mechanism (4) is connected to relay (2) to actuate said constraining mechanism. Relay (2) used in this system is having an interface of battery (5), fluid reservoir (1) with FLWI and an electromagnetic device with spring (10) of constraining mechanism (4). Current from battery (5) will flow to electromagnetic device (10) only when FLWI is active i.e. when fluid level is low. The electromagnetic device (10) will get energized and compresses when current flows through it, which in turn restrict the movement of accelerator pedal (7) by pulling the constraining sleeve (13). An override switch (6) is provided in the system as a safety measure to give some degree of freedom to accelerator pedal (7) when required. The constraining mechanism (4) consists of hollow cylinder (9) fixed to a collar sleeve (11), Electromagnetic device with spring (10) is provided on a said hollow cylinder (9), one end of said electromagnetic device with spring is seated in a groove (11a) provided on collar sleeve (11) and movable shaft (12) having slightly less diameter as compared to inner diameter of hollow cylinder (9) is fixed to a collar sleeve (14) and inserting said movable shaft inside hollow cylinder (9) in such a way that there should be sufficient gap (x) between movable shaft end (12a) and collar sleeve (11) to have a linear movement of movable shaft (12).
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Another end of said electromagnetic device with spring is also seated in a groove (14a) provided on collar sleeve (14). A constraining sleeve (13) is fitted to collar sleeve (14). Thus electromagnetic device with spring (10) has only one degree of freedom viz. translatory motion along the axis of the two cylinders (9, 12). Translatory motion between said two cylinders (9, 12) is guided by at least two anti friction balls (16) provided between contact surfaces of said two cylinders. Said anti friction balls (16) are provided on longitudinal slots cut (17) on said cylinders (9, 12). Because of above said arrangement whenever electromagnetic device with spring (10) moves, the shaft (12) along with constraining sleeve (13) moves. Said whole constraining mechanism (4) is mounted on firewall of the automobile.
Accelerator pedal (7) is pivoted at pivot point (8) and cable end (15) of said accelerator pedal is provided in such a way that the constraining sleeve (13) engages with it during energized state of electromagnetic device with spring (10). This constraining mechanism (4) helps in fully constraining the accelerator pedal (7) by energizing the electromagnetic device with spring (10).
When brake fluid level in the fluid reservoir goes below a specified level, relay (2) will draw current from the connection between fluid reservoir (1) and Instrument cluster (3), this small current closes the switch between vehicle battery (5) and constraining mechanism (4), hence current flows between vehicle battery (5) and constraining mechanism (4). Because of flow of current to electromagnetic device with spring (10) it energizes and gets compressed, due to which constraining sleeve (13) moves towards the cable end of accelerator pedal (7) and engages with it, and prevents acceleration of automobile.
When the level of fluid inside the reservoir (1) is sufficient then no current flows to electromagnetic device with spring (10), hence it remains in free condition
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which is shown in fig. 2a. At this condition accelerator pedal (7) operates normally and give response as per requirement.
An over-ride switch (6) is provided for partially decoupling the constraining mechanism (4) with accelerator pedal (7). This is done by partially energizing the electromagnetic device with spring (10) which is shown in fig.2c. Hence using an over-ride switch (6) vehicle can be towed but at very slow speed.
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. Foolproof system for warning of low level of hydraulic fluid for automobiles comprises of relay having an interface of battery, fluid reservoir with fluid level warning indicator and constraining mechanism mounted on firewall, wherein said constraining mechanism consists of hollow cylinder fixed to a collar sleeve; electromagnetic device with spring provided on a said hollow cylinder with one end seated in a groove provided on said collar sleeve; and a movable shaft fixed to another collar sleeve, slidably fitted into said hollow cylinder; another end of said electromagnetic device with spring is seated in a groove provided on collar sleeve of movable shaft and a constraining sleeve is fitted to said collar sleeve of movable shaft; cable end of accelerator pedal is provided in such a way that the constraining sleeve engages with it during energized state of electromagnetic device with spring.
2. Foolproof system for warning of low level of hydraulic fluid for automobiles as claimed in claim 1 wherein said movable shaft is slidably fitted into said hollow cylinder with sufficient gap between movable shaft end and collar sleeve of hollow cylinder to have a linear movement of movable shaft.
3. Foolproof system for warning of low level of hydraulic fluid for automobiles as claimed in claims 1 and 2 wherein an over-ride switch is provided in a system for partially decoupling the constraining mechanism with accelerator pedal.
4. Foolproof system for warning of low level of hydraulic fluid for automobiles as claimed in claim 1 to 3 wherein said relay interface is provided with a switch, which works on the feed back given by fluid level warning indicator, between battery and constraining mechanism.
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5. Foolproof system for warning of low level of hydraulic fluid for automobiles as claimed in claim 1 to 3 wherein said relay interface is provided with a resistive path, which works on the feed back given by override switch, between battery and constraining mechanism.
6. Foolproof system for warning of low level of hydraulic fluid for automobiles as claimed in claims 1 to 5 wherein antifriction balls are provided in slots at mating surfaces of hollow cylinder and movable shaft.
7. Foolproof system for warning of low level of hydraulic fluid for automobiles as claimed in claims 1 to 6 wherein said antifriction balls are provided in a same plane or at different planes.
8. Automobile provided with foolproof system for warning of low level of hydraulic fluid as claimed in claims 1 to 7.
9. Foolproof system for warning of low level of hydraulic fluid for automobiles substantially as herein described with reference to accompanying drawings.
Dated this 5th day of July 2007.

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ABSTRACT
Foolproof System For Warning Of Low Level of Hydraulic Fluid For Automobile
The present invention relates to a constraining mechanism for accelerator pedal during shortage of brake fluid composes of a relay, which allows the current to flow through to it when visual hazard lamp goes ON in instrument cluster. This current energizes an electromagnetic device with spring of the constraining mechanism leading to backward movement of shaft having swiveling constraining sleeve . This backward motion constrains the accelerator pedal and hence inhibits the vehicle to accelerate. An over-ride switch helps the driver to partially decouple the constraining mechanism from accelerator pedal, hence the vehicle can be towed safely at very low speed to the nearest service station.