FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"A NOVEL SYSTEM FOR GEAR NEUTRAL SENSING SYSTEM IN MANUAL TRANSMISSION OF MOTOR VEHICLES"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R&D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C, SATPUR,
NASHIK-422 007,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION DESCRIBES THE NATURE OF THE INVENTION AND MANNER IN WHICH IT IS TO BE PERFORMED

TECHNICAL FIELD OF THE INVENTION:
The present invention is related to a gear neutral sensing system in case of manual transmission of automotive vehicles. More particularly, the present invention related to Gear Neutral Sensing system using non-contact type proximity sensor for Safe Starting of vehicle for engine Start stop and remote Start control System.
BACKGROUND AND PRIOR ART SEARCH:
In certain applications like engine start stop and remote start control it is desirable to electronically detect when the gear transmission is disengaged or in neutral. For example, in an automobile having a manual transmission it may be desirable to detect whether the gear selection is neutral (disengaged) prior to starting an engine coupled to the transmission for start stop and remote start control. Most vehicles having these applications work well with automatic transmissions but such applications are not available with manual transmission. It may cause a serious accident if the vehicle is started while transmission is in gear. The automotive and similar manual transmission environments may be harsh for electronic detection components due to vibration forces, high and low temperatures, dust, dirt, and oil that may be present at or near the manual transmission.
A need thus exists for a robust electronic gear neutral detection system and method for a manual transmission that is easily installed, safe to use and reliable.
Various types of sensors for detecting gear neutral Sensing for automatic transmission has been proposed in past like United states patent number US4896267 discloses the for determining the condition of a manual transmission clutch and of a park/neutral gear in an automatic transmission, where the ratio of engine speed to vehicle speed is stored and compared to a previously stored ratio, the electronic speed control being disengaged if ratio of

engine speed to vehicle speed is different than the previously stored ratio by more than a predetermined amount.
United states patent number US3478851 discloses methods for automatic mechanical transmission systems wherein gear selection indication and shift decisions are made and/or executed based upon measured and/or calculated parameters such as engagement condition of the transmission, vehicle or transmission output shaft speed, transmission input shaft speed, engine speed, throttle position, rate of change of throttle position, rate of change of vehicle and/or engine speed and the like. It relates to a method for controlling an AMT system utilizing sensors for providing input signals indicative of the presence or absence of a transmission gear neutral condition, engine, transmission input shaft and transmission output shaft rotational speeds, etc. including sensing of a faulty signal from the gear neutral sensors and modifying the system operation logic in tolerance of such fault.
United state patent application US20080223167 discloses an two position contact type switch for determining neutral selection in an automated mechanical transmission comprising of a first piston and cylinder assembly for bi-directionally translating a first shift rail and a second piston and cylinder assembly for bi-directionally translating a second shift rail; providing a neutral sensor for indicating a neutral position of said second shift rail; moving said first piston and cylinder assembly and said first shift rail from side-to-side to center; and determining whether said neutral sensor provides a neutral indication when said second piston and cylinder assembly and said second shift rail is in a center position.
To avoid this present invention will use the non-contact type proximity sensor for gear neutral sensing for manual transmission configuration for safe starting of vehicle for engine Stop Start and remote starting system. This system is immune to environmental contamination and manufacturing variations in transmission parts.

OBJECTS OF THE PRESENT INVENTION:-
The main object of the present invention is to provide a gear neutral sensing system for manual transmission system of automotive vehicles.
Another object of the present invention is to provide gear neutral sensing system to be used in combination with Engine stop Start System control module to provide a safety signal indicating whether the manual transmission is in neutral and indicating whether or not it is safe to start the engine automatically.
Another object of the present invention is to provide gear neutral sensing system to be used in combination with Engine stop Start module for the automatic start of the vehicle when critical condition is detected by a set of predefined states (battery voltage below the threshold level, booster pressure level) if transmission is in neutral.
Still another object of the present invention is to Provide gear neutral sensing system that can accommodate the manufacturing variations in transmission parts (variation in sensor mounting base due to tasting, deformation of pivot plate during tightening, play between pivot mounting hole and the bolt dimension, leakage path of magnetic field due to ferrous environment in transmission area).
Further object of the present invention is to provide a novel gear neutral sensing system that prevents the starter motor and engine components failures due to itching of vehicle.
Still further object of the present invention is to Provide gear neutral sensing system which is easy to install with a minimum amount of labour, cost and time and can be mass produced in an automated and economical manner.
Accordingly the invention provides A gear neutral sensing system for manual transmission for automotive vehicle comprises a non-contact type proximity

sensor and a magnet mounted on transmission base and shifting lever respectively; an electronic control unit receiving input from the said sensor. based on the air-gap between said sensor and magnet in geared and neutral condition to detect whether the gear selection is neutral (disengaged) prior to starting an engine coupled to the manual transmission; an interface connected between the out put of the said electronic control unit and the vehicle ON/OFF starter, switch; the vehicle battery leads connected to said the electronic control unit for monitoring reference voltage; an embedded software is loaded in the said electronic control unit is programmed in such way such a way that
I. If the air gap is Ok, then check if the vehicle is neutral then allow
remote start of the vehicle if battery voltage is low and booster
pressure level is low; II. If the air gap is not OK or Vehicle is not in neutral or if battery
voltage is not low or booster pressure level is not low then do not
allow remote start of the vehicle; III. If the air gap is Ok, then check if the vehicle is neutral then allow
start & stop of the vehicle if preconditions are OK.
DESCRIPTION OF THE FIGURES:-
Figure 1 is a schematic illustration of the components and interconnections of the automatic mechanical transmission control system of the present invention.
Figure 2 shows partial sectional view of a transmission gear shifting arrangement and operator's operating angle including a gear neutral sensor.
Figure 3 shows symbolic illustrations, in the form of a flow chart, illustrating the preferred manner of practicing the method of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION:-
In accordance with the present invention, the drawbacks of the prior art have been overcome or minimized by providing an electronic non-contact type proximity sensor for mechanical transmission systems wherein gear selection and shift indication of the presence or absence of a gear neutral condition based on air gap between gear neutral sensor and magnet, and the like are also utilized to make decisions for Start stop and remote start control on the vehicle.
The predetermined logic rules or programs by which the various input signals are processed include a method for detecting a fault in the input signals from the gear neutral sensors and a method for modifying the predetermined logic in response to a sensed fault to provide an acceptable, if less than optimal, set of logic rules for continuing operation of the AMT system until such time as the fault ceases or is corrected.
A gear neutral condition sensor input signal is considered to be faulty if the value thereof is not, within acceptable tolerance limits, indicative of the true engaged or disengaged condition of the transmission or transmission section monitored thereby. Thus, the invention to provides a new and improved control method for automatic mechanical transmission systems which involves sensing and identifying a fault in the gear neutral sensors and modifying the logic routines or algorithms by which the system is operated in tolerance of such sensed fault.
This system consists of digital Hall Effect proximity sensor (A) and a magnet holder (B) and this arrangement on manual transmission gives a reliable output signal when the transmission gear shifting lever (C) is in neutral gear. In neutral position the south magnetic pole is close to Hall Effect proximity sensor, so the switch is ON. in either of the gear condition (1, 2, 3, 4, 5, Reverse), the south magnetic pole has moved too far away, so the switch turns OFF. This ensures that starting of the engine happens only when the power train is open.

The neutral sensor is connected to an electronic control unit The said control unit is loaded with an embedded software which is programmed as per the flow diagram illustrated in the figure 3.
1. Remote Start ControI(Along with Gear Neutral sensor)
I. If the air gap is Ok, then check if the vehicle is neutral then allow remote start of the vehicle if battery voltage is low and booster pressure level is low
II. If the air gap is not OK or Vehicle is not in neutral or if battery voltage is not low or booster pressure level is not low then do not allow remote start of the vehicle
2. Start stop Control(Alongwith Gear Neutral sensor
III. If the air gap is Ok, then check if the vehicle is neutral then allow start & stop of the vehicle if preconditions are OK.
IV. If the air gap is not OK or Vehicle is not in neutral or preconditions are not OK then do not allow remote start of the vehicle
Once the Ignition is switched ON, the Gear neutral Sensor interface(l), remote start control (2) and Start Stop System (3) will powered ON and initialization of the each ECU will be done. If the initialization of remote Start control system or Start stop system fails, then the corresponding system will go into fail-safe mode and both the system will be de-active during that particular Ignition cycle. If the both the systems were working, then the gear neutral sensor interface will check for air gap between gear neutral sensor and magnet and identify the gear neutral condition. If the gear neutral sensor detects the vehicle is in neutral then based on the conditions of battery voltage threshold level and booster pressure level threshold the system will allow to remote start of vehicle for safe starting of vehicle. Similarly if gear neutral sensor interface detects the vehicle is in neutral and all other preconditions are met for Start stop system activation then based on the gear neutral condition the Stop Start system will allow starting and stopping of vehicle in Start stop mode.
As a feature of present invention, a starter motor safety control feature is there in gear neutral sensor interface which will allow the cranking of vehicle only when the manual transmission is in neutral condition or power train is

disengaged by pressing of clutch. It will not allow the cranking of vehicle if the gear is not in neutral condition and clutch is not pressed. This will prevent the failure of starter motor and failure of engine components due to itching of vehicle in geared condition.
It would be unsafe to start a vehicle if there is a known malfunction in gear neutral sensor interface system of the vehicle. As a feature of the present invention, a diagnostics mode is there to detect any abnormality/ failure mode in the gear neutral sensor which will detect the failure modes (Output short to Ground, Connector open, Output short to Supply voltage) based on the output voltage level. The different failure mode identified as based on the output voltage level is provided in the following Table.

FEATURES OUTPUT VOLTAGE
1. OUTPUT SHORT TO GROUND 0 - 0.4 VDC
2. NEUTRAL POISTION OUTPUT. 0.4 - 1.4 VDC
3. CONNECTOR OPEN 1.4-3.8VDC
4. GEAR POSTION OUTPUT. 3.8-4.3VDC
5. OUTPUT SHORT TO SUPPLY. 4.3-5.0VDC
Thus, a gear neutral sensing for manual transmission for automotive vehicle comprises of a non-contact type proximity sensor and a magnet mounted on transmission base and shifting lever respectively. Based on the air-gap between them in geared and neutral condition to detect whether the gear selection is neutral (disengaged) prior to starting an engine coupled to the manual transmission, the present invention can be used for safe starting and stopping of vehicle in combination with Engine Stop Start control, Remote start control and Starter motor control purpose. The system can accommodate the manufacturing variations in transmission parts. The system has a diagnostics mode is there to detect the any abnormality/ failure mode in the gear neutral sensor which will detect the failure modes. The system prevents starter motor and engine components failures due to itching of vehicle.

WE CLAIM:-
1. A gear neutral sensing system for manualtransumission for automotive
vehicle comprises a non-contact type lroximity sensor and a magnet mounted on transmission base and shifting lever respectively; an electronic control unit receiving input from the said sensor based on the air-gap between said sensor and magnet in geared and neutral condition to detect whether the gear selection is neutral (disengaged) prior to starting an engine coupled to the manual transmission; an interface connected between the out put of the said electronic control unit and the vehicle ON/OFF starter switch; the vehicle battery leads connected to said the electronic control unit is embedded reference voltage; wherein the said electonic control unit is embedded with software programmed in such way
I. If the air gap is Ok, then check if the vehicle is neutral then allow remote start of the vehicle if battery voltage is low and booster pressure level is low;
II. If the air gap is not OK or Vehicle is not in neutral or if batterty
voltage is not low or booster pressure level is not low then do not
allow remote start of the vehicle;
III. If the air gap is Ok, then check if the vehicle is neutral then allow
start & stop of the vehicle if preconditions are OK.

2. A gear neutral sensing system as claimed in claim 1 wherein said sensor is Hall Effect proximity sensor (A) and a magent holder (B) with the said arrangement on manual transmission gives a reliable output signal when the transmission gear shifting lever (C) is in neutral gear; in

neutral position the south magnetic pole is close to Hall Effect proximity sensor, so the switch is ON and in either of the gear condition (1, 2, 3, 4, 5, Reverse), the south magnetic pole has moved too far away, so the switch turns off.