FIELD OF THE INVENTION

The present subject matter relates to hall-sensor based electrical-circuit and in particular relates to gear-position determination system in automobiles.
BACKGROUND
Sensors for the positions of gearboxes are known in the art. These sensors are provided from the design of a gearbox and are integrated with it, often at the level of the actuators making it possible to make gear changes. For these sensors, various technologies are applied. For example, positioning sensors based on a potentiometer are known to detect the position of an actuator and to deduce therefrom the position of the gearbox, that is to say if and which gear ratio is engaged.
Other technologies, such as Hall Effect or inductive magnetic technologies have also recently found their application in the context of position sensors for gearboxes. In an example prior-art 1, Fig. 1 refers a Korean patent publication KR20130054528. The same refers a gearshift motion detection device of a transmission cable for an automatic transmission vehicle provided to improve fuel efficiency by stopping an engine and by reducing consumption of fuel when the vehicle stops and when a gearshift is in neutrality. A gearshift motion detection device of a transmission cable for an automatic transmission vehicle comprises a connection member (210), a magnet, a moving member (230), a metal member, a hall sensor (250), and an engine control unit (260). One end of the connection member is fixed to a guide pipe (130) of a mounting socket (140), and the other end includes a connection unit (211). The magnet is fixed to the connection unit and forms a magnetic field by corresponding to the metal member. The moving member is moved along the linear movement of a connector (110) when a gearshift is operated so that a length is changed. The metal member is connected to the other end of the moving member in order to move along the movement of the moving member. The hall sensor detects the change of a magnetic force of a magnetic field formed between the magnet and the metal member. The engine control unit controls operation of an engine (300) by receiving information on the magnetic force detected by the hall sensor.

In the prior art example, as referred in Fig. 1, KR20130054528, it is mentioned that magnet is assembled in a coupling-part which is moving Member. Due to high-speed movement in coupling part magnet can dislocate. Due to presence of moving member, metal member & coupling part, a Hall IC may not detect the presence of Target. As the surrounding members are ferrous parts, the Hall IC sensor receives differential gauss.
In another example prior art as referred in Fig. 2, a patent publication EP1882871 refers the gearbox of a motor vehicle comprising an actuating rod of the (3) gear ratios is movable in rotation and in translation over limited strokes and a predefined position sensor (17) comprising a magnetized target (19) attached to said actuating rod (3) characterized in that the sensor comprises a Hall Effect (21) component operable to measure a magnetic field in three orthogonal directions (Bx, By, Bz) to determine the position and orientation of the target (19) in the space and to deduce therefrom the position of the gear-box.
As may be observed in EP 1882871, magnet is mounted on selector shaft inside transaxle. Due to extreme operating temperatures (>150°C) & Vibration level the magnet can dislocate or get demagnetized. Assembly of magnet inside transaxle is complicated, also magnetizing fixtures required to magnetize such custom magnets is complex. The cost of magnet is higher due to large size & complex geometry. Handling of magnet & assembly on the shifter shaft needs to be done with due care. Also, the sensor calibration may be required at system-level which makes vehicle level assembly process complicated.
There lies at least a need of the magnetic circuit based on hall sensor for gear position detection that does not undergo degradation and dislocation of magnet due to extreme temperature (>150°C) & and is also resistant to any vibration to the electro-magnetic circuit.
Moreover there lies a need of an assembly where a standardised IC package can be used without modification.
SUMMARY
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.

The present subject matter at least relates to a hall sensor based neutral & other gear position detection system comprising:
an electronic sensor assembly in turn comprising:
a hall sensor and a ring magnet disposed with respect to each other at a predetermined distance; and
a PCB connected to the hall sensor through an electrical connector to identify a position sensed by hall-sensor;
and
a movable assembly comprising a truncated ferrous article and operable to generate a magnetic flux density at a predetermined position with respect to the sensor assembly and enable the identification of position of the movable assembly by the sensor assembly. The movable assembly is disposed in the vicinity of the electronic sensor assembly.
In an example, the hall sensor and PCB may be connected through a bus-bar to prevent any customization of leads of the sensor IC and use the sensor in standard form.
In an example, the truncated ferrous article is secured to a gear shaft with respect to the magnetic circuit to vary the magnetic flux density as sensed at the hall sensor.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the

accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Figure 1 and 2 refer a state of the art scenario;
Fig. 3 (a and b) refers a magnetic-circuit consisting of permanent 'Ring' shape magnet and Hall IC (i.e. a hall sensor IC), in accordance with the present subject matter;
Fig 4 to Fig. 6 refers perspective views of the truncated profile ferrous target sensor, in accordance with the present subject matter;
Fig. 7 illustrates a neutral gear, in accordance with the present subject matter;
Fig 8 illustrates a neutral gear, in accordance with the present subject matter;
Fig. 9 refers other gear position, in accordance with the present subject matter;
Fig. 10 illustrates ring shape magnet and the Hall IC as spaced apart from each other by a specific distance (Z), in accordance with the present subject matter;
Fig. 11 refers dimension of the truncated profile ferrous target, in accordance with the present subject matter;
Fig. 12 refers an electrical connection arrangement, in accordance with the present subject matter;
Fig. 13 illustrates the flux densities when the truncated target is in front of hall IC i.e. in neutral condition, in accordance with the present subject matter;
Fig. 14 illustrates the flux densities when the truncated target is in front of hall IC i.e. in other gear condition, in accordance with the present subject matter;
Fig. 15 provides another perspective view of flux densities when the truncated target is positioned in front of the hall IC i.e. in neutral condition, in accordance with the present subject matter;
Fig. 16 provide a graphical representation of magnetic flux density (G) vs angle (deg), in accordance with the present subject matter; and
Fig. 17 and Fig. 18 provide perspective view of magnet holder which locks the Ring Magnet & hall IC, in accordance with the present subject matter.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the

drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION OF FIGURES
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting. Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
Fig. 3 (a and b) refers a position detection system 300, which in turn comprises an electronic sensor assembly 302. The sensor assembly 302 comprises a hall sensor IC 306, and a ring magnet 308 disposed with respect to the hall sensor IC 306 at a predetermined distance. More specifically, Fig. 3a refers a magnetic-circuit consisting of permanent 'Ring' shape magnet 308 and Hall IC 306 (i.e. a hall sensor IC). A PCB 310 is connected to the hall sensor 306 through an electrical connector to identify a position sensed by hall-sensor. The Hall IC 306 is placed at the center of magnet 308 (i.e. magnet center and IC center are same) in a magnet-holder 312 and is spaced apart from the magnet 308 by a certain distance. Additionally, a bus-bar 314 is used to extend the hall IC 306 leads as shown in Fig. 3b & complete a magnet holder assembly placed inside the sensor housing with the help of a PCB assembly. Specifically, the hall sensor IC 306 and the PCB 310 are connected through the bus bar 314.
As further depicted in Fig. 3b, a movable-assembly 304 comprises a truncated ferrous article 316 and operable to generate different magnetic-flux densities at a plurality of positions with respect to the electronic sensor assembly 302 as referred in Fig. 3a. More

specifically, the truncated ferrous target 316 has a round shape with slot- profile that generates distinct magnetic-flux densities based on the positions of target profile in front of the sensor. Accordingly, the sensor IC 306 within the assembly 302 can clearly identify neutral & other gear positions. The Hall IC 306 is user-programmable type and is accordingly configured to detect whether the vehicle is in neutral or other-gear. Specifically, the PCB 310 connected to the hall sensor IC 306 is configured to generate a plurality of signal indicating the plurality of position of the movable assembly 304 as detected by the sensor assembly 302.
As may be observed, the description of Fig. 3 refers a truncated profile ferrous target based sensor (neutral & other gear) for detecting position of shifter shaft in transaxle of 4 wheelers. More particularly, the present subject matter deals with the ring-magnet 308 & the hall IC 306 along with the truncated shape ferrous target profile 316 designed to generate magnetic flux densities in presence of truncated ferrous target profile 316 to identify neutral & other gear conditions. In absence of truncated ferrous target profile, other gear positions may be identified. The present subject matter's position detection system 300 as based on a unique magnetic circuit is designed to detect small/thin ferrous targets 316 which move or slide but does not undergo rotation.
Fig 4 to Fig. 6 refers the perspective views of the truncated profile ferrous target sensor 300 designed with unique magnetic circuit 302 along with a movable assembly 304 having a truncated shape ferrous target profile 316.
Fig. 7 and 8 illustrates a neutral gear condition, while Fig. 9 refers other gear position corresponding to non-neutral position.
Fig. 10 refers position of RING shape magnet 308 and the Hall IC 306 as spaced apart with respect to each other by a specific distance (Z).
As shown in Fig. 4 and Fig. 10, the 'RING' shape magnet 308 is placed inside the magnet holder 312 and Hall IC 306 is positioned such that 'RING' shape magnet 308 and the Hall IC 306 are spaced apart by a specific distance (Z) with the help of the magnet holder 312. The Hall IC 306 is joined to PCB 310 along with the bus bar 314 using resistance welding technique and the complete assembly is held by the PCB 310. The magnetic circuit is enclosed in magnet holder 312 with a positive locking for magnet 308 & Hall IC 306 as later

depicted in Fig. 17 and Fig. 18. The magnet 308 is placed in such a way that North Pole faces towards the target 316 as shown in Fig. 7 and later in Fig. 13 and Fig. 14.
Fig. 11 refers a dimension 'dl' of the truncated profile ferrous target as being about 1.6 times the thickness 't'. The ring magnet profile of the ring magnet 308 is decided based on various magnetic simulations & experimental-trials in such a way that enough flux densities are available to differentiate other gear and neutral condition.
Fig. 12 refers an electrical-connection arrangement. The hall IC 306 defined by standard IC's are available with Length 'L' of leads to achieve a connection of such leads with the PCB 310. A bus bar 314 is designed which connects the IC leads to the PCB 310. While IC leads & the bus bar 314 end LI is Resistance / Spot welded, the end L2 of the bus bar 314 is soldered with the PCB 310. The same at least avoids the requirement of IC's with customized IC leads and standard Hall sensor ICs may be used through the usage of bus bar 314, thereby substantially reducing the cost. & hence the cost is reduced.
Fig. 13 and 15 illustrate the flux densities when the truncated target 316 is in front of hall IC 306 i.e. in neutral condition, while Fig. 14 provides another perspective view of flux densities when the truncated target 316 is positioned away from hall IC 306 i.e. in other gear condition.
More specifically, Fig. 13, 14 & 15 provide another perspective views compared to preceding Figures 1-12. In Fig. 13, when target profile 316 is in front of hall IC 306, the magnetic flux lines generate from North Pole of magnet & pass through the ferrous target 316 and the Hall IC 306 to form a low-reluctance path as also further shown in Fig. 15. Accordingly, the PCB 310 is configured to generate a first type of signal corresponding to a low reluctance path pertaining to the flux density generated by the truncated ferrous article 316. The PCB 310 is configured to generate the first type of signal based on the truncated ferrous article 316 moving near the hall sensor IC 306 at a first position. The first position is defined as a neutral position
As shown in Fig. 14, when target profile 316 is away from the hall sensor IC, the magnetic reluctance is high as shown. Accordingly, the PCB 310 is configured to generate a second type of signal corresponding to a high reluctance path pertaining to the flux density generated by the truncated ferrous article 316. The PCB 310 is configured to generate the

second type of signal based on the truncated ferrous article 316 moving farther from the hall sensor IC 306 at a second position at either side of the hall sensor IC 306. The second position is defined as a non-neutral position.
The truncated ferrous article 316 is secured to a shaft with respect to the electronic sensor assembly and configured to vary the magnetic flux density by a predetermined margin while moving from the first position to the second position. When truncated ferrous target 316 moves after shifting gear as shown in Fig. 14, it creates a variable reluctance path and a variable density of magnetic flux lines passing through Hall IC 306. Such changed magnetic flux density is measured by the Hall IC 306 to identify whether vehicle is in neutral condition of Fig. 13 or Fig.15 or other gear condition as shown in Fig.14.
Fig. 16 provides a graphical representation of magnetic flux density (G) vs angle (deg). As shown in the figures, following may be the observations:
Gl = Magnetic flux density when Truncated target 316 is in front of Magnetic Circuit 302 at point PI.
G2 = Magnetic flux density when truncated target 316 is away from Magnetic Circuit 302 at point P2.
The relation between Gl and G2 are, G1>G2 stands with respect to point PI and P2. A configuration may be done when the differential magnetic flux density AG should be > (100+X) G between Gl and G2 at position PI and P2, where X is the numerical value in Gauss.
As may be understood from the description in the preceding figures 13 to 16, to detect the thin / small ferrous targets precisely, delta flux density change is necessary. The unique magnetic circuit 302 provides the delta-flux with respect to change in P1-P2 along with transition of the target.
Fig. 17 and Fig. 18 provide perspective view of magnet holder 312 which locks the Ring Magnet 308 & hall IC 306. More specifically, the ring magnet 308 is rigidly disposed in the electronic sensor assembly 302 and restricted from undergoing motion in at-least one dimension. The magnetic circuit is packaged in single housing as shown in Fig 17a, 17b, 18a & 18b. As shown in Fig 17a & 17b, the Hall IC 306 is located & fixed in X, Y & Z axis. As shown in Fig 18a & 18b, 'Ring' shape magnet 308 is located & fixed in X & Y axis. To arrest

movement of magnet in Z axis, snaps 1802 are provided in Magnet Holder 312 as shown in Fig 18a & 18b. This type packaging of magnetic circuit ensures efficient functioning of sensor under thermal, vibration conditions.
At least by virtue of afore-depicted description of drawings, the present subject matter facilitates detection of small, thin ferrous targets which move or slide at less than 1 RPM. Moreover, standardised IC package may be used without modification from supplier which reduces cost. The Magnetic circuit & Hall IC are enclosed in single housing, hence degradation, dislocation of magnet due to extreme temperature (>150°C) & vibration does not happen.
The arrangement in accordance with the present subject matter offers exceptional stability throughout lifetime and across temperature changes. The same renders ease of Design for Manufacturing / Assembly i.e. DFA & DFM, and does away with the need of using "IC Integrated with back bias Magnet". Further, the present subject matter renders diagnostic ability.
While specific language has been used to describe the present disclosure, any limitations arising on account there to, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment.

We Claim:

1. A position detection system (300) comprising:
an electronic sensor assembly (302) comprising:
a hall sensor (306); and
a ring magnet (308) disposed with respect to the hall sensor (306) at a predetermined distance; and
a PCB (310) connected to the hall sensor (306) through an electrical connector to identify a position sensed by hall-sensor;
and
a movable-assembly (304) comprising a truncated ferrous article (316) and operable to generate different magnetic-flux densities at a plurality of positions with respect to the electronic sensor assembly (302).
2. The position detection system (300) as claimed in claim 1, wherein the PCB (310) is configured to generate a plurality of signal indicating the plurality of position of the movable assembly as detected by the sensor assembly.
3. The position detection system (300) as claimed in claim 2, wherein the PCB (310) is configured to generate the plurality of signals comprising:
a first type of signal corresponding to a low reluctance path pertaining to the flux density generated by the truncated ferrous article (316); and
a second type of signal corresponding to a high reluctance path pertaining to the flux density generated by the truncated ferrous article (316).
4. The position detection system (300) as claimed in claim 3, wherein the PCB (310) is
configured to generate the first type of signal based on the truncated ferrous article (316)
moving near the hall sensor (306) at a first position.
5. The position detection system(300) as claimed in claim 3, wherein the PCB (310) is
configured to generate the second type of signal based on the truncated ferrous article (316)

moving farther from the hall sensor (306) at a second position at either side of the hall sensor (306).
6. The position detection system (300) as claimed in claim 1, wherein the hall sensor (306) and PCB (310) are connected through a bus bar (312).
7. The position detection system (300) as claimed in claims 4 and 5, wherein the truncated ferrous article (316) is secured to a shaft with respect to the electronic sensor assembly (302) and configured to vary the magnetic flux density by a predetermined margin while moving from the first position to the second position.
8. The position detection system (300) as claimed in claim 1, wherein the ring magnet (308) is rigidly disposed in the electronic sensor assembly (302) and restricted from undergoing motion in at-least one dimension.
9. The position detection system (300) as claimed in claim 7, wherein the truncated ferrous article (316) is secured to a gear shaft with respect to the electronic sensor assembly (302) and defines the first position as a neutral position and the second position as a non-neutral position.
10. The position detection system (300) as claimed in claim 9, wherein the truncated ferrous
article (316) is configured to vary the magnetic flux density by the predetermined margin
while moving from the neutral position to the non-neutral position.