DESC:
Field of the Present Invention:

The present invention relates to an improved switching method and electromechanical switch assembly of a vehicle. Particularly, the present invention relates to a contactless electromechanical switch assembly for switching of ON/OFF functions like stop lamp, cruise control, etc. More particularly, the present invention relates to a improved switching method for a contactless electromechanical switch.

Background of the Present Invention:

In recent time contactless switch assembly is widely being used in automobiles for switching on and off various functions like stop lamp, cruise control etc. These switches replace the mechanical contact switches by electromagnetic proximity sensor or sensing element and magnet. The said contactless switches have longer life in comparison to mechanical contact switch. A conventional contactless switch method is disclosed in Figure 1 wherein a cylindrical magnet is being sensed by a hall element so as to switch on or off the requisite function. Problem of miss-triggering had been observed in the existing type contactless switching method due to early detection of magnetic field by the sensing element. Moreover, in prior art one possible solution to solve the early detection was that height between sensing element and magnet is to be increased or the sensitivity of the sensing element is to be reduced. But due to mechanical assembly size constraint, the said height cannot be increased. In addition to solve the early detection, sensitivity of sensing element is to be reduced but by reducing the sensitivity, magnetic hysteresis increases which results in loss in switching point accuracy of the conventional contactless switching method. Hence there is a need to solve the problem of miss-triggering and loss in switching point accuracy. Yet another major problem faced by the applicant was un-intentional switching of hall sensor through a foreign or external cylindrical or rectangular or the like magnet when brought near to the said electromechanical switch assembly.

Summary of the Present Invention:

An electromechanical switch comprising a housing comprising space an interior and an exterior, a casing comprising a hollow region and adapted to receive the housing, a resiliently loaded magnet sub-assembly being slidably supported on one or more guiding tracks formed in the interior of the housing; the said magnet sub-assembly comprising a magnet having a magnetic axis parallel to the motion of the magnet sub assembly disposed in the housing by means of a spring; a centerline of the magnet is transverse to the motion of the magnet sub-assembly and delineate the position of the magnet sub assembly supported in the interior of the housing, an actuating shaft comprising a proximal end being disposed in the interior of the housing so as to remain in contact with the magnet sub-assembly, a distal end operatively coupled with brake pedal so that movement of the brake pedal causes actuation of the actuating shaft thereby allowing movement of the spring loaded magnet sub-assembly in longitudinal direction towards the centerline of the hall sensor, a PCB assembly accommodated in the housing; the PCB assembly comprises one or more unipolar Hall sensors having a centerline of the sensor parallel to the centerline of the magnet sub-assembly; a sensing element of the hall sensor is located on the centerline of the sensor adapted to detect the change in magnetic flux due to longitudinal movement of the magnet sub-assembly to provide signal indicative of activation of brake light, cruise control, etc

In the present application Applicant has attempted physical and virtual experimentations in order to solve unintentional switching of hall sensor by the foreign magnet (not shown in the drawing) which is either cylindrical or rectangular. In one of the experiments, said magnet had been removed from the said electromechanical switch assembly and said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly. Observation was that hall sensors mounted on the PCB miss-triggered from the said foreign magnet due to switching by receiving required magnetic flux density from said magnet. Reason behind said hall sensor used in the said switch gets on when receive required magnetic flux. In another experiment, applicant assembled said magnet in the said electromechanical switch assembly in and said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly. Observation was that hall sensors mounted on the PCB had not miss-triggered from the said foreign magnet. Reason behind no miss-triggering was that the magnetic flux density applied by north pole of said magnet which is inventive, neutralizing the magnet flux density applied by from south pole of said foreign magnet. Moreover hall sensor used is unipolar and gets on by south pole magnetic flux and no effect of north pole magnetic flux. Furthermore when said electromechanical switch assembly is in no switching condition, said inventive magnet faces the hall sensor with north pole. In this case if said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly by keeping south pole magnetic flux, observation reveals no miss-triggering or switching of hall sensor due to neutralizing the magnet flux density applied by from south pole of said foreign magnet with the magnetic flux density from north pole said inventive magnet. In another case when said electromechanical switch assembly is in switching condition, said inventive magnet faces the hall sensor with south pole. In this case if said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly by keeping south pole magnetic flux, observation reveals switching of hall sensor due to required magnet flux density applied by from south pole of said inventive magnet and additional contribution of foreign magnet with the magnetic flux density from south pole. In another case when said electromechanical switch assembly is in switching condition or no switching condition, said inventive magnet faces the hall sensor with south pole or north pole and said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly by keeping north pole magnetic flux, observation reveals no switching of hall sensor due to hall sensor active only when required south pole magnetic flux is received.

The present invention provides an improved switching method for vehicular switches. The vehicular switch comprises a case, shaft, magnet sub assembly, PCB sub assembly, spring and housing. Refer to figure 9, In order to solve the problem of miss-triggering by early detection leading to switching point inaccuracy as mentioned in prior art, various design of experiments had conducted on electromagnetic simulation software and on test magnets and test sensors physically. Rectangular magnet with the magnetic axis in the direction of magnet sliding, moves from initial position to X-mm early the intermediate position. Now as the north pole of the magnet is towards the unipolar sensor which senses only south pole of the magnet, will not be detecting the north pole magnetic field of the magnet.

Refer to figure 2, the next experimentation have conducted with the rectangular magnet rectangular magnet further move to X-mm to match the centerline of said sensor with the centerline of the magnet. Now as said sensor has to detect magnetic field density from south pole of the magnet only, said sensor will just detect the magnetic field density from south pole required to operate the sensor. At this point sensor will just detect magnetic flux in order to switch any or all of the said function. This rectangular magnet was having thickness, width, length and surface magnet flux density equal to 1.5mm, 5mm, 10mm and 190mT~230mT respectively, had been brought from no switching position to X-mm early than the centerline of the said sensor and found that the sensor was not detecting the magnetic flux density as it was detecting in case of cylindrical magnet. But sensor just detect the magnetic flux density when the centerline of the magnet matches with the centerline of the sensor. The reason of just detecting is that the said sensor being south pole unipolar detecting only south pole of the magnetic flux density alienated by the centerline of the magnet. Moreover, this sensing occurs only when centerline of said sensor matches with the centerline of the said magnet.

Brief Description of Drawings:

Figure 1 illustrates an existing switching method for an electromechanical switch.
Figure 2a-2d illustrates an electromechanical switch according to an embodiment of the present invention.
Figure 3 illustrates exploded view of an electromechanical switch according to an embodiment of the present invention.
Figure 4 illustrates exploded view of a magnetic sub-assembly according to an embodiment of the present invention.
Figure 5 illustrates sectional view along plane A-A of figure-2b according to an embodiment of the present invention.
Figure 6 illustrates sectional view along plane D-D of figure-2b according to an embodiment of the present invention.
Figure 7illustrates sectional view along plane C-C of figure-5 according to an embodiment of the present invention.
Figure 8-10 illustrates a switching method of the electromechanical switch according to an embodiment of the present invention.
Figure 11-13 illustrates sectional view of the electromechanical switch according to an embodiment of the present invention.

Detail Description of the present invention:

While the invention is susceptible to various notifications and alternative forms, specific embodiments thereof has been shown by way of examples in the figures and will be described in details below. It should be understood, however that is not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims.
Before describing in details embodiments it may be observed that the novelty and inventive step that are in accordance with the present invention resides in improved switching method and the vehicular switches. It is to be noted that a person skilled in the art can be motived from the present invention and modify the various constructions of assembly. However, such modification should be constructed within the scope and spirit of the invention.

Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefits of the description herein.

The terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a setup, device that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such device. In other words, one or more elements in a system or apparatus proceeded by “comprises….a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus. The following paragraph explains present invention wherein improved switching method and the vehicular switches.

Accordingly, it is an aim of the present invention to overcome at least one of the problem associated with the prior existing switches.

In order to solve the problem of miss-triggering by early detection leading to switching point inaccuracy as mentioned in prior art, inventors have conducted various experiments on electromagnetic simulation as well as on test magnets and test sensors physically. In the first experimentation, the said cylindrical magnet of length, diameter and surface magnetic flux density equal to 3mm, 3 mm and 510mT~530mT respectively having south pole towards the hall sensor with operating point and releasing point 3.5mT~28mT and 2.5mT~22.5mT and height or air gap between hall sensor mounted on fixed PCB and moving magnet to be 0.5mm to 1.5mm, moves towards the intermediate position or centerline of the sensor so as to switching on the function by matching of both centerline of censor and magnet but there is a early detection or sensing by X mm occurs.

Accordingly, the present invention provides an electromechanical switch comprising:
a housing comprising an interior and an exterior;
a casing comprising a hollow region and adapted to receive the housing;
a resiliently loaded magnet sub-assembly being slidably supported on one or more guiding tracks formed in the interior of the housing; the said magnet sub-assembly comprising a magnet having a magnetic axis parallel to the motion of the magnet sub assembly disposed in the housing by means of a spring; a centerline of the magnet is transverse to the motion of the magnet sub-assembly and delineate the position of the magnet sub assembly supported in the interior of the housing
an actuating shaft comprising:
a proximal end being disposed in the interior of the housing so as to remain in contact with the magnet sub-assembly,
a distal end operatively coupled with brake pedal so that movement of the brake pedal causes actuation of the actuating shaft thereby allowing movement of the spring loaded magnet sub-assembly in longitudinal direction towards the centerline of the hall sensor;
a PCB assembly accommodated in the housing; the PCB assembly comprises one or more unipolar Hall sensors having a centerline of the sensor parallel to the centerline of the magnet sub-assembly; a sensing element of the hall sensor is located on the centerline of the sensor adapted to detect the change in magnetic flux due to longitudinal movement of the magnet sub-assembly to provide signal indicative of activation of brake light, cruise control, etc.

In an embodiment of the present invention, the magnet provided in the magnet sub assembly is a rectangular magnet having7mm-10mm length, 1mm-2mm thickness and 3mm-4mm width.

In another embodiment of the present invention, the magnet has two magnetic poles distributed on the surfaces, on either side of the centerline of the magnet perpendicular to the magnetic axis.

In a further embodiment of the present invention, the housing have a bottom wall, a top wall, two opposite side walls, a closed end wall and an open end wall.

In still another embodiment of the present invention, the one or more hall sensors is positioned at a distance greater than 9mm, preferably 11 mm from the top wall of the housing.

In yet another embodiment of the present, the one or more hall sensors is positioned at a distance greater than 5mm, preferably 16 mm from the bottom wall of the housing.

In a further embodiment of the present invention, the one or more hall sensors is positioned at distance greater than 4mm, preferably 9 mm from the both opposite walls of the housing.

In still another embodiment of the present invention, the one or more hall sensors is positioned at distance greater than 5mm, preferably 18 mm from the open end wall of the housing at switching condition.

In another embodiment of the present invention, the unipolar hall sensors provided in the PCB assembly configured to start detecting either north -pole or south-pole space of the magnet, when the centerline of the magnet coincides with centerline of the hall sensor.

In a further embodiment of the present invention, a stopping face is provided in the interior of the casing for abutting with the shaft in actuated condition.

In yet another embodiment of the present invention, guiding tracks formed in the interior section of the housing body and adapted to slidably support a magnet sub assembly;

In yet another embodiment of the present invention, an air gap in the range of 0.8mm-2mm, preferably 1mm is being provided between the hall sensor and the magnet.

In another embodiment of the present invention, the hall sensor mounted on the PCB have sensitivity in the range of 2mT~12.5mT, preferably 3.5mT.

In still another embodiment of the present invention, the magnet is positioned at distance (f) 3.6mm from one or more sensor, range to be 3.1~4.5 mm when in no switching condition.

In yet another embodiment of the present invention, the magnet is positioned at distance (g) 12.4mm from one or more sensor, range to be 1.9~2.9 mm when in switching condition at full stroke.

The following description describes the present invention with reference to Figures 1 to 15 according to an embodiment of the present invention.

Figures 2a-3 illustrates an electromechanical switch assembly (1) according to an embodiment of the present invention. Referring to Figures 2a, 2d and 3, the electromechanical switch assembly of the present invention comprises a casing (2) and a housing (3) forming an encapsulation for accommodating various components of the switch assembly such as a shaft (4), a magnet sub assembly (5), a spring (6), and a PCB sub assembly (7).

Referring to figure 3, the casing (2) has a box shaped geometry, formed by side walls (8), an open end (9) and a rear end wall (10). One or more locking grooves (11) are provided on the side walls (8) for securing the casing (2) to the housing (3) for forming an encapsulation. The rear end wall (10) is incorporated with a hollow cylindrical trough (12) extending perpendicularly and outwardly from the rear end wall (10) of the casing (2). The hollow cylindrical trough (12) is adapted to receive the actuating shaft (4) in the longitudinal direction. The term ‘longitudinal direction’ herein refers to a direction perpendicular to the plane of the rear end wall (10). The actuating shaft (4) is a rigid structure having a proximal end (13) and a distal end (14) and is adapted to move longitudinally upon actuation of brake pedal (not shown in Figures).

A skilled artisan can envisage the construction of brake pedal and other components which transfers the actuation force from the brake pedal to the distal end (14) of the actuating shaft (4).

The distal end (14) is adapted to pass through the hollow cylindrical trough (12) of the casing (2). The distal end (14)of the actuating shaft (4) emerges from an open end (12a) of the hollow cylindrical trough (12) for contacting the brake pedal. The proximal end (13) of the actuating shaft (4) is disposed in the interior of the housing (3) and remains in contact with the magnet sub assembly (5). The proximal end (13) is a flange structure. The flange structure is an extended diameter portion and provided with a first curved surface (13a) and a second flat surface (13b) opposite to the first surface (13a). The second surface (13b) is provided to abut with a stopping face (10a) of the rear end wall (10) under actuated condition of the electromechanical switch (as shown in Figure 10). The first curved surface (13a) of the proximal end (13) of the actuating shaft (4) remains in contact with the magnet sub-assembly (5). The magnet sub assembly (5) is resiliently disposed in the housing (3) and adapted to move in a longitudinal direction upon actuation by actuation shaft (4). The PCB sub assembly (7) is accommodated in the housing (3) so as to be located over the magnet sub assembly (5). The PCB sub assembly (7) comprises one or more Hall sensors or Hall element (7a) and is configured to detect magnetic flux or change in magnetic flux due to the movement of the magnet sub assembly (5) and to provide signal indicative of activation of brake light, cruise control etc. The hall sensor (7a) provided in the PCB assembly (7) is a unipolar hall sensor (7a), which detects magnetic flux of either south-pole or north-pole of the magnet. The unipolar hall sensor (7a) will remain in fixed position during operation of the electromechanical switch. The unipolar hall (7a) sensor only detects the south pole of the magnet.

Figure 3 illustrates a housing (3) of an electromechanical switch according to an embodiment of the present invention. The housing (3) can be made of any suitable material preferably a thermoplastic material. Referring to Figure 3, the housing (3) comprises an exterior and an interior. The interior of the housing (3) is defined by a hollow region delineated by a bottom wall (16) , a top wall (17), two opposite side walls (18, 19), a front open end (20) and a rear closed end wall (21). The housing (3) is provided with plurality of guiding tracks(22, 23) (as shown in Figure 7)for slidably supporting the magnet sub assembly (5).

Referring to Figure 3, the housing (3) is provided with a locating pin (24)(as shown in Figure 6) extending towards the open end (20) from the rear end wall (21) of the housing (3) for locating the spring (6). The housing (3) is provided with slots (25) extending longitudinally between the open end (20) and closed end wall (21) are formed on the side walls (18, 19). A plurality of apertures (26) is provided on the closed end wall (21) for projecting there through the terminals (15) of the PCB sub assembly (7) for electrical connections with the driving circuit. The exterior (3a) of the housing (3) is provided with one or more snaps (27) adapted to cooperate with the locking grooves (11) provided on the casing (2) for securing the housing (3) with the casing (2) to form an encapsulation.
Figures 4 illustrate a magnet sub assembly (5) of the electromechanical switch (1) according to an embodiment of the present invention. Referring to Figures 4, the magnet sub assembly (5) comprises an adapter (28) and a socket (29) accommodating a magnet (30). In an embodiment, the magnet (30) is a rectangular magnet. The magnet (30) has a thickness (T) of 1mm, a width (W) of 3mm and a length (L) of 7mm. The magnet (30) has a surface magnet flux density equal to 155mT~195mT.The socket (29) is a rigid structure having a slot (31) being sized to removably receive a magnet (30).

Refer to Figure 4, the rectangular magnet is assembled by press fitting and snap locked or to be glued in the slider or adapter so as to be movable with magnet sub assembly to deliver the required magnetic flux density to sensed by hall element. In an embodiment of the present invention the rectangular magnet can be with the magnet sub assembly by insert molding. The magnet sub-assembly can be formed by insert molding process before magnetization of the magnet. The magnetization of the sub-assembly including magnet, can be done after insert molding process.

As shown in Figure 4, the slot (31)may be provided with one or more crushing ribs (32) to snugly hold the magnet (30) in the slot (31). The socket (29) can be secured with the adapter (28). For this purpose, a plurality of snaps (33) is provided on outer periphery of the socket (29) for facilitating mounting of the socket (29) on the adapter (28).

Figure 5illustrates sectional view taken along plane A-A of the electromechanical switch shown in figure 2b. Figure 6 illustrates sectional view along plane D-D of the electromechanical switch shown in figure 2b.

Figure 7illustrates sectional view taken along plane C-C of the electromechanical switch (1) shown in Figure 5. Referring to Figure 6 and 7 , a cylindrical hole (34) is formed on one of the side face of the adapter (28) which faces the closed end wall (21) when the magnet sub assembly (5) is disposed in the housing (3). The cylindrical hole (34) is sized to accommodate the spring (6) located on the locating pin (24) formed in the housing The slots (25) are sized to accommodate the PCB sub assembly (7).

Applicant has attempted physical and virtual experimentations in order to solve unintentional switching of hall sensor by the foreign magnet (not shown in the drawing) which is either cylindrical or rectangular. In one of the experiments, said magnet (30) had been removed from the said electromechanical switch assembly and said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly. Observation was that hall sensors mounted on the PCB miss-triggered from the said foreign magnet due to switching by receiving required magnetic flux density from said magnet. Reason behind said hall sensor used in the said switch gets on when receive required magnetic flux. In another experiment, applicant assembled said magnet(30) in the said electromechanical switch assembly in and said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly. Observation was that hall sensors mounted on the PCB had not miss-triggered from the said foreign magnet. Reason behind no miss-triggering was that the magnetic flux density applied by north pole of said magnet (30) which is inventive, neutralizing the magnet flux density applied by from south pole of said foreign magnet. Moreover hall sensor used is unipolar and gets on by south pole magnetic flux and no effect of north pole magnetic flux. Furthermore when said electromechanical switch assembly is in no switching condition, said inventive magnet (30) faces the hall sensor with north pole. In this case if said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly by keeping south pole magnetic flux, observation reveals no miss-triggering or switching of hall sensor due to neutralizing the magnet flux density applied by from south pole of said foreign magnet with the magnetic flux density from north pole said inventive magnet (30) . In another case when said electromechanical switch assembly is in switching condition, said inventive magnet (30) faces the hall sensor with south pole. In this case if said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly by keeping south pole magnetic flux, observation reveals switching of hall sensor due to required magnet flux density applied by from south pole of said inventive magnet (30) and additional contribution of foreign magnet with the magnetic flux density from south pole. In another case when said electromechanical switch assembly is in switching condition or no switching condition, said inventive magnet (30) faces the hall sensor with south pole or north pole and said foreign magnet had been brought nearer to boundary wall of the said electromechanical switch assembly by keeping north pole magnetic flux, observation reveals no switching of hall sensor due to hall sensor active only when required south pole magnetic flux is received.

As shown in figure 6 and 7, the magnet (30) and one or more hall sensors are positioned in the housing at specific location to achieve highest switching point accuracy and to avoid the miss-triggering of the electromechanical switch due to magnetic flux of foreign magnet. In an embodiment, the one or more hall sensors are fixed at a distance (a) which is greater than 9mm, preferably 11 mm from the top wall (17) of the housing (3). The one or more hall sensors is positioned at a distance (b) which is greater than 9 mm, preferably 16 mm from the bottom wall (16) of the housing (3). The one or more hall sensors is fixed at distance ( c) which is greater than 4mm, preferably 9 mm from the both opposite walls (18, 19) of the housing (3).The one or more hall sensors is positioned at distance (d) which is greater than 5 mm, preferably 18 mm from the open end wall (20) of the housing (3) at switching condition. The one or more hall sensors is fixed at distance (e) greater than 5mm, preferably 10 mm from the closed end wall (21) of the housing (3) at switching condition. The distances (d) and (e) shown in Figure 6 are the distances at the switching condition of the switch i.e. when the shaft is at full stroke or an final actuated position. In an embodiment, Hall sensor which senses only south pole of the magnet (30), has been selected to be of the maximum available i.e. lowest operating point and lowest hysteresis. In an embodiment, this is because lowest hysteresis will furnish the highest switching point accuracy. In an embodiment, Hall sensor selected is having sensitivity in the range of 2mT~12.5mT, preferably 3.5mT. Bar magnet specification has been kept in such a way that it neutralizes the magnetic flux density of foreign magnet on hall sensor. Various magnetic experimentations had been conducted in order to achieve the zero magnetic flux density for achieving the magnet specification and distance between the hall sensor and foreign magnet. Based on the experimental results magnet sizes can be 7mm length (L), 1 mm thickness (T)& 3 mm width (W) whereas range to be 7~10 mm for length, 1~2 mm for thickness & 3~4 mm width. This magnet specification with range has been found suitable to neutralise the effect of foreign magnet for un-intentional switching of any of hall sensor mounted on PCB assembly. Referring to Figures 6 and 13, the magnet is positioned at distance (f) 3.6mm from one or more sensor, range to be 3.1~4.5 mm when in no switching condition. The magnet is positioned at distance (g) 12.4mm from one or more sensor, range to be 1.9~2.9 mm when in switching condition at full stroke.

In an embodiment of the present invention, a plurality of projections is formed on the adapter for slidably supporting the magnet sub assembly on the guiding tracks formed in the housing.

Figure 8-10 illustrates switching method of the electromechanical switch of the present invention

Referring to figure 8, the rectangular magnet (30) has a centerline of the magnet (30) in the direction perpendicular to the longitudinal direction. The centerline of the magnet delineates the position of the magnet sub-assembly (5) in the electromechanical switch (1). The magnet (30) has a magnetic axis parallel and perpendicular to the longitudinal direction and centerline of the magnet respectively. The magnet(30) has two magnetic poles north-pole and south-pole, which are distributed on the surface on either side of the centerline of the magnet. The north-pole and the south-pole of the magnet faces the rear closed end wall (21) and the front open end wall (20) of the housing (3) respectively. The hall sensor provided on the PCB has a centerline of the sensor which delineates an intermediate position. The hall sensor is a unipolar hall sensor which only detects the magnetic flux from the south pole of the magnet. The polarity of the magnet can be reversed i.e. the north-pole faces the rear closed end wall and the south-pole faces the front open end wall, accordingly the unipolar hall sensor can be selected or configured to detect only north pole of the magnet to trigger the electromechanically switch. The centerline of the sensor is parallel and perpendicular to the centerline of the magnet and longitudinal direction respectively. The centerline of the sensor remains in fixed position and the centerline of the magnet moves with the movement of the magnet. A distance (D) between the centerline of the magnet and the centerline of the sensor is a variable distance. The air gap between the unipolar hall sensor and the magnet can be fixed in the range of 0.5mm to 1.5mm.

In another embodiment of the present invention the north-pole and the south-pole of the magnet faces the front open end wall (20) and the rear closed end wall (21) of the housing (3), respectively. The unipolar hall sensor provided on the PCB is configured to detect the magnetic flux from the north pole of the magnet (30).
As shown in figure 8, when the brake pedal (not shown in figures) is actuated the magnet (30) moves from the initial position D= +A mm to a position D=+x mm. At the said position D= +x mm only magnetic field from the north-pole of the magnet(30) is accessible for detection by unipolar hall sensor. The said magnetic flux from the north-pole remains undetected, as the unipolar hall sensor is configured to detect magnetic flux from south-pole. At D= +x mm position the magnetic flux from the magnet (30) is undetectable by the unipolar hall sensor.

Referring to figure 9, when the brake pedal is further pressed, the rectangular magnet (30) moves from the (D=+x mm) to the intermediate position(D = 0 mm). The magnetic field of the magnet is undetectable by the unipolar hall sensor in the region between the initial position (D= +A mm) and the intermediate position (D= 0 mm), excluding the intermediate position (D=0 mm). The intermediate position (D=0 mm) is defined as a position where the centerline of the magnet coincides with the centerline of the sensor. At the intermediate position (D = 0 mm) only magnetic flux from the south-pole of the magnet (30) is accessible for sensing by unipolar hall sensor. At the said position (D= 0 mm) the unipolar hall sensor starts detecting requisite magnetic flux from south-pole of the magnet (30) to trigger the stop lamp (brake light).

Referring to figure 10, when the brake pedal is in completely pressed condition, the rectangular magnet (30) moves from the intermediate position (D= 0 mm) to the final position (D = -B mm). At the said position (D= -B mm) the shaft abuts with the stopping face of the rear end wall (10) of the casing (2) to restrict the movement of the actuation shaft (4) (as shown in figure-13).As shown in figure 10, the magnetic field direction changes when the magnet (30) moves from the intermediate position (D= 0 mm) to the final position (D= -B mm). The change in the direction of the magnetic field results in detection of the magnetic flux by the unipolar hall sensor. At the position D= -B mm only magnetic field from the north-pole of the magnet is accessible for detection by unipolar hall sensor. The said magnetic flux from the north-pole is detected by unipolar hall sensor, as the said sensor is configured to detect magnetic flux from south-pole. In a region defined between the intermediate position (D= 0 mm) and the final position (D= -B mm), the magnetic flux is detectable by the unipolar hall sensor configured to detect magnetic flux from the south pole of the magnet.

When the brake pedal (not shown) is released, the magnet (30) starts moving towards the intermediate position(D =0 mm) from the final position (D= -B mm). The magnetic flux from the south-pole is detectable by the unipolar hall sensor, when the magnet moves from the final position (D= -B mm) to the intermediate position (D =0 mm). Further movement of the magnet (30) from the intermediate position (D= 0 mm) to the final position (D= +A mm), the magnetic flux from the south-pole of the magnet is undetectable by the unipolar hall sensor. As the magnetic flux remains undetected by the hall sensor, the brake lights will extinguish (turn-off) (switch-off).
Figures 11-13 illustrate actuation of electromechanical switch of the present invention.

As depicted in figure 11, the electromechanical switch (1) is in non-actuated condition. In the non-actuated condition, the magnet sub-assembly (5) is at initial position (D=0 mm) as the brake pedal remains in released state i.e. no force is applied on the brake pedal. The brake pedal is operatively coupled with the distal end (14) of the actuating shaft (4) so as to apply a force on the distal end (14) of the shaft (4) when the brake pedal is in released position. As shown in figure 11, the magnet sub-assembly (5) is at initial position (D= +A mm) where no magnetic flux is detected by unipolar hall sensor. The unipolar hall sensor mounted on the PCB is immobile with respect to the sliding magnet provided in the magnetic sub-assembly (5). At initial position (D= +A mm), the second flat surface (13b) of the proximal end (13) of the actuation shaft (4) is not in contact with the rear end wall (10) of the casing (2). The first curved surface (13a) of the actuation shaft (4) is in point contact with the magnet sub assembly (5) due to its hemispherical geometry. The spring (6) which is resiliently in contact with the magnet sub assembly (5) is in compressed state in the non-actuated position of the switch.

When the brake pedal is pressed or an external force is applied on the brake pedal, the force applied on the distal end of the shaft by the brake pedal getting released.

Referring to figure 12, when the force of the brake pedal on the distal end is removed, the spring (6) expands and pushes the first curved surface (13a) of the actuation shaft (4) in longitudinal direction thereby resulting in a sliding movement of the magnet sub assembly (5) on the guiding tracks. As shown in figure 12 the actuating shaft (4) pushes the magnet sub-assembly (5) in longitudinal direction from the initial position (D= +A mm) to intermediate position (D= +0 mm) by a predetermined distance. At intermediate position (D= +0 mm) the hall sensor provided in the PCB assembly starts detecting the requisite magnetic flux for switching the brake lights, cruise control etc.
Figure 13 illustrates further movement of the magnet sub assembly from the intermediate position (D= +0 mm) to the final position (D= -B mm), towards the rear end wall (21) of the housing (3). At the final position (D= -B mm) the second flat surface (13b) of the proximal end (13) abuts with the stopping face of the rear end wall (10) of the casing (2) to restrict movement of the actuation shaft (4).

In an embodiment of the present invention, plurality of hall sensors are provided in the PCB assembly to trigger various operations in predetermined interval of time by using a magnet (30). Each hall sensor is located at different distance on the PCB to deliver accurate sensing of magnetic flux from a magnet at specific time interval.

The said method of switching in a contactless manner according to the present invention, furnishes a high precision linear or sliding sensing and solves miss-triggering or early detection problem which exists in the prior art switches. Also, the said method of switching, does not require more height or air gap between the sensor and magnet as required in prior art. It is due to the reason that sensing start only when centerline of the magnet and centerline of sensor matches to receive pole wise magnetic flux only.

The said inventive magnetic switching arrangement can be deployed in the other products like penal switches, HVAC switches, any kind of pedal switches, power window switches, lever combination switches etc. wherever there is precision switching requirement in a sliding manner when at least a magnet is moving and at least a sensor is fixed by mounting it on printed circuit board. Figure 2d illustrates perspective view of a contactless switch assembly wherein above said method of contactless switching is integrated so as to demonstrate application of above said method. The said contactless switch assembly is used to switch various functions like stop lamp, cruise control, electronic stability function, engine start stop function, etc. The said contactless switch assembly is mounted in a bracket for stop lamp pedal in a vehicle.

Advantages of present invention:
1. No miss-triggering of switching point by the foreign magnet.
2. No early detection of magnetic field by the hall sensor
3. Exact and precision switching point accuracy.
4. Least possible air gap is possible between hall sensor and magnet. The air gap is not dependent on value of magnetic flux density of magnet and value of sensitivity or operating or releasing magnetic point of the hall sensor.
5. Smallest possible size of magnet which results in compact product design.
6. Economic sensing arrangement as hall sensor is one of the less cost sensor.
7. The said inventive magnetic switching arrangement can be deployed in the other products like penal switches, HVAC switches, any kind of pedal switches, power window switches, lever combination switches etc. wherever there is precision switching requirement in a sliding manner when at least a magnet is moving and sensor is fixed by mounting it on printed circuit board.

,CLAIMS:
1. An electromechanical switch comprising:

a housing comprising an interior and an exterior;

a casing comprising a hollow region and adapted to receive the housing;

a resiliently loaded magnet sub-assembly being slidably supported on one or more guiding tracks formed in the interior of the housing; the said magnet sub-assembly comprising a magnet having a magnetic axis parallel to the motion of the magnet sub assembly disposed in the housing by means of a spring; a centreline of the magnet is transverse to the motion of the magnet sub-assembly and delineate the position of the magnet sub assembly supported in the interior of the housing
an actuating shaft comprising:
a proximal end being disposed in the interior of the housing so as to remain in contact with the magnet sub-assembly,
a distal end operatively coupled with brake pedal so that movement of the brake pedal causes actuation of the actuating shaft thereby allowing movement of the spring loaded magnet sub-assembly in longitudinal direction towards the centreline of the hall sensor;
a PCB assembly accommodated in the housing; the PCB assembly comprises one or more unipolar Hall sensors having a centreline of the sensor parallel to the centreline of the magnet sub-assembly; a sensing element of the hall sensor is located on the centreline of the sensor adapted to detect the change in magnetic flux due to longitudinal movement of the magnet sub-assembly to provide signal indicative of activation of brake light, cruise control, etc

2. The electromechanical switch as claimed in claim1, wherein the magnet provided in the magnet sub assembly is a rectangular magnet having7mm-10mm length, 1mm-2mm thickness and 3mm-4mm width.
3. The electromechanical switch as claimed in claim 1, wherein the magnet have two magnetic poles distributed on the surfaces, on either side of the centreline of the magnet perpendicular to the magnetic axis.

4. The electromechanical switch as claimed in claim 1, wherein the housing have a bottom wall, a top wall, two opposite side walls, a closed end wall and an open end wall.

5. The electromechanical switch as claimed in claim 2 or 4, wherein the one or more hall sensors is positioned at a distance greater than 9mm, preferably 11 mm from the top wall of the housing.

6. The electromechanical switch as claimed in claim 2 or 4, wherein the one or more hall sensors is positioned at a distance greater than 5mm, preferably 16 mm from the bottom wall of the housing.

7. The electromechanical switch as claimed in claim 2 or 4, wherein the one or more hall sensors is positioned at distance greater than 4mm, preferably 9 mm from the both opposite walls of the housing.

8. The electromechanical switch as claimed in claim 2 or 4, wherein the one or more hall sensors is positioned at distance greater than 5mm, preferably 18 mm from the open end wall of the housing at switching condition.

9. The electromechanical switch as claimed in claim 1, wherein the unipolar hall sensors provided in the PCB assembly configured to start detecting either north -pole or south-pole of the magnet, when the centreline of the magnet coincides with centreline of the hall sensor.

10. The electromechanical switch as claimed in claim 1, a stopping face is provided in the interior of the casing for abutting with the shaft in actuated condition.

11. The electromechanical switch as claimed in claim 1, wherein guiding tracks formed in the interior section of the housing body and adapted to slidably support a magnet sub assembly;

12. The electromechanical switch as claimed in claim 1, wherein an air gap in the range of 0.8mm-2mm, preferably 1mm is being provided between the hall sensor and the magnet.

13. The electromechanical switch as claimed in claim 1, wherein the hall sensor mounted on the PCB have sensitivity in the range of 2mT~12.5mT, preferably 3.5mT.

14. The electromechanical switch as claimed in claim 2 or 4, wherein the magnet is positioned at distance (f) 3.6mm from one or more sensor, range to be 3.1~4.5 mm when in no switching condition.

15. The electromechanical switch as claimed in claim 2 or 4, wherein the magnet is positioned at distance (g) 12.4mm from one or more sensor, range to be 1.9~2.9 mm when in switching condition at full stroke.