FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
A neutral position sensing 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
INVENTOR
Patel Hiralkumar G
An 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 specification particularly describes the invention and the manner in which it is to be performed.

TECHNICAL FIELD
The present invention generally relates to transmission systems of automobiles and more particularly relates to a neutral position sensing system for controlling operation of the internal combustion engine.
BACKGROUND OF THE DISCLOSURE
Automobiles equipped with internal combustion engine (hereafter referred to as 'engine'), and transmission systems often employ a start-stop system or stop-start system that is configured to automatically shut down and restart the engine. This is done in order to reduce the amount of time the engine spends in idling, thereby improving fuel economy and reducing emissions. This is particularly advantageous for automobiles that spend significant amount of time waiting at traffic lights or frequently come to a stop in traffic jams.
Typically, in order to trigger the start-stop system, neutral position of the transmission system is required to be detected. Conventionally, such detection of the neutral position is done through use of a sensor and a magnet. The sensor may be located on transmission housing, and the magnet on a selector shaft. However, in such an arrangement due to long selection stroke, the neutral position detection magnet needs to be larger in size. In an alternative arrangement, the sensor is mounted on gear shifter housing and the magnet on gearshift lever. However, in this arrangement the detection of the neutral position is indirect and therefore often has poor accuracy. Further, due to space constraint it is not feasible to use conventional sensor and magnet mechanism since they require separate location in transmission or on the gearshift lever and the gear shifter housing.
OBJECTS OF THE INVENTION
The objective of invention is to provide a neutral position sensing system which is simple, accurate and compact in size.

Another objective of the preset invention is to provide a neutral position sensing system which is easy to assemble and is cost effective.
Further objects and features of the invention will become apparent from the following detailed description when considered in conjunction with the drawings.
SUMMARY OF THE INVENTION
The various embodiments of the present invention, disclose a neutral position sensing system for a transmission system having a top cover assembly and a shifter shaft passing through the top cover assembly. The neutral position sensing system includes a shift finger extending from the shifter shaft, a magnetic member mounted on said shift finger and configured to move with said shifter shaft, a breather assembly carried by the top cover assembly inline with the magnetic member when the shifter shaft in neutral position and a sensor is integrated with said breather assembly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 illustrates a sectional view of a neutral position sensing system for an internal combustion engine, according to an embodiment of the invention,
FIG. 2 illustrates a sectional view of a breather assembly of the neutral position sensing system of FIG. 1, according to an embodiment of the invention,
FIG. 3 illustrates a top view of an interlock assembly of the neutral position sensing system of FIG. 1, according to an embodiment of the invention, and
FIG. 4 illustrates another top view of the interlock assembly of the neutral position sensing system of FIG. 1, according to an embodiment of the 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.
It is to be noted at this point that all of the above described components, whether alone or in any combination, are claimed as being essential to the disclosure, in particular the details depicted in the drawings and reference numerals in the drawings are as given below.
A neutral position sensing system 100, in accordance with an embodiment of the present invention is illustrated in FIGS. 1 through 5. The internal combustion engine may be adapted to drive an automobile (not shown) and may be petrol, diesel, gasoline engine or the like. In automobile with manual transmission, a transmission system controls the power from the internal combustion engine to wheels of the automobile. Further, an electronic control unit (ECU) 116 may be provided on the automobile, which may be capable of regulating supply of fuel to the internal combustion engine, during operation of the automobile. The neutral position sensing system 100 of the present inventions directs the electronic control unit (ECU) 116 based on the position of gears of the transmission system, to regulate supply of fuel to the internal combustion engine (also referred to as 'engine').
The neutral position sensing system 100 includes a shift finger 102. As shown in FIG. 1, the shift finger 102 may extend perpendicularly from a portion of a shifter shaft 104 for selecting and displacing a gear engagement within the transmission positioned within an enclosed space 106 in the transmission system. The Shift shaft is selectively rotatable and movable between neutral and different gear position. Therefore, as the shifter shaft 104 is moved longitudinally, to and fro, the shift finger 102 also moves in the same manner. Further, as the shifter shaft 104 moves angularly the shifter finger 102 also moves angularly, along an imaginary plane perpendicular to a longitudinal axis of the shifter shaft 104. An interlock piece 108

is also mounted on the shifter shaft 104, on top and bottom of the shift finger 102. The interlock piece 108 allows the angular movement of the shifter finger 102, therewithin. A slot 110, best shown in Fig. 3, is provided on the interlock piece 108. In the disclosed embodiment, the slot 110 is provided on a top face of the interlock piece 108, and has an arched configuration.
As best shown in FIG. 1, a bracket 112 extends from the shift finger 102. The bracket 112 has an L-shaped configuration with an end connected on a top surface of the shift finger 102, a body portion passing through the slot 110 of the interlock piece 10$, and a free end positioned beyond the interlock piece 108 but within the enclosed space 106. A magnetic member 114 is provided at the free end portion of the bracket 112. In an embodiment of the present invention, the magnetic member 114 may be a permanent magnet detachably connected to the free end portion of the bracket 112 and moves with the shifter shaft 104. Particularly, the magnetic member 114 is configured to move angularly and linearly with the movement of the shift finger 102, which moves with the shifter shaft 104.
Referring again to FIG. 1 along with FIG. 2, the neutral position sensing system 100 further includes a breather assembly 200. The breather assembly 200 is carried by a top cover assembly 202 of the transmission system and positioned in such a way that the breather assembly will be inline with the magnetic member 114 when the shift shaft 104 is in neutral position. Accordingly, the neutral position sensing system 100 of the present invention may be packaged on an existing top cover area of the transmission system and there is no need of without disturbing or altering the existing configuration. It may be apparent to those skilled in that are that the top cover assembly 202 covers the transmission system. The top cover assembly 202 includes preexisting holes to allow fitment and passage of components, such as shifter shaft 104 and the breather assembly 200.
The breather assembly 200 is provided with four equally spaced breathing holes (not numbered) and four equally spaced locking lug (not numbered). When pressure inside the transmission system goes below, a predetermined pressure for

example, atmospheric pressure, the transmission system tends to draw air through the breathing holes from outside. During this, a breather cap 204 will be pulled downwards, thereby locking a passage between a breather tube 206 and the breather cap 204. However, when the pressure inside the transmission system goes above the atmospheric pressure, the transmission system tends to expel air through the breathing holes. During this, the breather cap 204 will be push upwards and a gap gets created between the breather tube 206 and the breather cap 204. Thus, the pressurized air is blown out of the transmission system.
The neutral position sensing system 100 furthermore includes a neutral position sensor 208 integrated with the breather assembly 200. Particularly, the sensor 208 is pasted on a free end of the breather tube 206 of the breather assembly 200, along a longitudinal axis A-A' thereof. The sensor 208 is adapted to sense presence, absence and/or density of a magnetic field and send a proportional signal in terms of percentage pulse width modulation (PWM) signal to the electronic control unit (ECU) 116 through connectors 210. As will be evident to those skilled in the art, the connectors 210 may also provide requisite power for the operation of the sensor. In an embodiment of the present invention, the sensor 208 is a Hall Effect sensor. In other embodiments of the present invention the sensor 208 may be any other sensor capable of sensing presences and absence of a magnetic field, without deviating from the spirit of the present invention.
Referring now to FIG. 3 and FIG. 4, which are top views of the neutral position sensing system 200. In FIG. 3, the magnetic member 114 of the shift finger 102 is shown to be in line with the sensor 208 mounted on the free end of the breather tube 206 of the breather assembly 200, i.e. the magnetic member 112 is positioned along the longitudinal axis A-A' of the breather tube 206. In such an alignment, the magnetic member 112 will be proximate to the sensor 208. Accordingly, the sensor 208 will sense a predetermined amount of magnetic field and a proportional volume of percentage Pulse Width Modulation (PWM) signal is being transmitted to the electronic control unit (ECU) 116 through the connectors 210. This alignment of

the magnetic member 112 with the sensor 208 will occur, when the transmission system is in neutral position.
During operation of the transmission system a driver moves the gearshift lever to change the transmission gear. When the driver moves the gearshift lever in its selection plane such that the gear is not changed i.e. no gear is selected, the interlock piece 108 and the shift finger 102 move up and down along the longitudinal axis A-A' the breather tube 206 of the of the gearshift lever. Again in such movement of the shift finger 102, the magnetic member 114 remains in alignment with the sensor 208, however there is change in proximity of the magnetic member 114 and the sensor 208. This change in proximity of the magnetic member 114 and the sensor 208 leads to change output of the sensor 208. The range, in which the percentage Pulse Width Modulation (PWM) varies during the selection movement, is considered neutral.
When the driver shifts the gear through the gearshift lever, the shifter shaft 104 will provide rotary motion to the shift finger 102. The rotary motion of interlock piece 108 is locked during gear shifting through the transmission system housing wall. A detent ball will ride over the profile on the shift finger 102 and moves into the groove for gear position. During this, the bracket 112 will rotate with the shift finger 102 carrying the magnetic member 114. Resultantly, the magnetic member 114 may no longer remain inline with the sensor 208 (as best shown in FIG. 4) i.e. the magnetic member 114 may get positioned at an offset from a longitudinal axis A-A' of the breather tube 206. Since the sensor 208 and the magnetic member 114 are not in line, a weaker magnetic field will be sensed by the sensor 208, leading to huge reduction in percentage Pulse Width Modulation (PWM) of the sensor 208.
The percentage Pulse Width Modulation (PWM) signal generated by sensor 208, during various stages of gear shifting continuously goes to the electronic controlled unit (ECU) through the connectors 210. As will be evident, the in-gear and neutral position of the transmission system have large difference in percentage Pulse Width Modulation PWM, the electronic controlled unit (ECU) can easily detect the in-

gear and neutral position. Based on the detection of the in-gear and neutral position of the transmission system, the electronic controlled unit (ECU) can take an appropriate action like turning OFF or turning ON supply of fuel to the cylinders of the internal combustion engine.
In one embodiment of the present invention, the sensor 208 of the neutral position sensing system 100 upon detecting that the magnetic member 114 is proximate thereto, i.e. the automobile is in the neutral position, will communicate with the electronic control unit (ECU) 116 to turn-off the engine. Likewise, the sensor 208 of the neutral position sensing system 100 upon detecting that the magnetic member 114 is distal therefrom, i.e. the automobile is in the in-gear position, will communicate with the electronic control unit (ECU) 116 to turn-on the engine.
The foregoing description provides specific embodiments of the present invention. It should be appreciated that these embodiment are described for purpose of illustration only, and that numerous other 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.

Referral Numerals Description
100 Neutral position sensing system
102 Shift finger
104 Shifter shaft
106 Enclosed space
108 Interlock piece
110 Slot
112 Bracket

114
Magnetic member
200 Breather assembly
202 Top cover assembly
204 Breather cap
206 Breather tube
208 Neutral position sensor
210 Connectors
116 Electronic Control Unit

We claim
1. A neutral position sensing system for a transmission system having a top cover assembly and a shifter shaft for selecting and displacing a gear engagement passing through said top cover assembly, said neutral position sensing system comprising:
a shift finger extending from the shifter shaft,
a magnetic member mounted on said shift finger and configured to move with said shifter shaft,
a breather assembly carried by said top cover assembly,
wherein said breather assembly positioned inline with said magnetic member when said shifter shaft is in neutral position and,
a neutral position sensor is integrated with said breather assembly.
2. The neutral position sensing system as claimed in claim 1, wherein said
breather assembly comprising
a breather cap having a plurality of holes, and
a breather tube having a plurality of holes and a stopper tab, said sensor being positioned within said breather tube.
3. The neutral position sensing system as claimed in claim 1, wherein said sensor is pasted within said breather tube of said breather assembly.
4. The neutral position sensing system as claimed in claim 1, wherein said sensor is a Hall-Effect sensor.
5. The neutral position sensing system as claimed in claim 1, wherein said sensor is configured to communicate with said electronic control unit through connectors to turn-off an internal combustion engine, when said magnetic member is positioned along a longitudinal axis of said breather tube and said sensor.

6. The neutral position sensing system as claimed in claim 1, wherein said sensor is configured to communicate with said electronic control unit through connectors to turn-on an internal combustion engine, when said magnetic member is portioned at an offset from a longitudinal axis of said breather tube and said sensor.
7. The neutral position sensing system as claimed in claim 1, further comprising a bracket extending from said shift finger, said bracket carrying said magnetic member at a free end thereof.
8. The neutral position sensing system as claimed in claim 7, wherein said bracket extending from said shift finger has an L-shaped configuration.
9. The neutral position sensing system as claimed in claim 1, wherein said magnetic member is a permanent magnet.