FIELD OF THE INVENTION
The present invention relates to an 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 magnet sub assembly of a
contactless electromechanical switch assembly.
BACKGROUND OF THE INVENTION
Generally electromechanical switch assemblies have been widely in use in
automobiles for a long time for switching on and off singular or multiple functions
like stop lamp, cruise control, electronic stability function, engine start stop
function, etc. An existing vehicle switch similar to this invention is depicted in
figure 1. Figure 1 depicts an electromechanical switch (100) as an existing wherein
a magnet (101) is mounted on a resiliently loaded actuation shaft (102). A first end
(102a) of the actuation shaft (102) has a cylindrical hollow section to receive a
spring (103). A second end (102b) of the shaft is operatively coupled with the
brake pedal of the vehicle. The actuation shaft (102) moves in a direction along the
length of the actuation shaft (102) upon actuation by the brake pedal. Upon
actuation by the brake pedal, the actuation shaft (102) moves under the force of the
spring (103) and the magnet (101) comes closer to the hall sensors on the PCB
assembly (104) to detect a change in magnetic field and initiate an electric signal.
Main problem with the prior art is the inaccuracy in switching point due to tilting
of shaft upon actuation by the brake pedal of a vehicle. This tilting of shaft occurs
because of sliding and part manufacturing clearance required between the shaft and
casing part.
In other words, researchers are constantly working to develop a user friendly and
technically advanced electromechanical switch.
3
SUMMARY OF THE INVENTION
The present invention relates to an electromechanical switch comprising a casing
comprising a hollow region and adapted to receive a housing. The housing
comprising an exterior and an interior, defined by a bottom wall, a top wall, two
opposite side walls, a closed end wall and an open end. A first guide track formed
on the side walls of the housing, and a second guide track formed on the bottom
wall of the housing. A resiliently loaded magnet sub-assembly accommodating a
magnet disposed in the interior of the housing movable along a longitudinal
direction; and comprising a plurality of projections extending laterally towards the
opposite side walls and the bottom wall of the said housing. The switch comprises
an actuating shaft having a proximal end being disposed in the interior of the
housing so as to remain in contact with the magnet sub-assembly; and 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. The switch comprises a PCB
assembly accommodated in the housing. The PCB assembly comprises one or
more Hall sensors adapted to detect change in magnetic flux due to movement of
the magnet sub-assembly and to provide signal indicative of activation of brake
light, cruise control etc.
BRIEF DESCRIPTION OF FIGURES
Further aspects and advantages of the present invention will be readily understood
from the following detailed description with reference to the accompanying
figures of the drawings. The figures together with a detailed description below, are
incorporated in and form part of the specification, and serve to further illustrate
the embodiments and explain various principles and advantages but not limiting
4
the scope of the invention. In the accompanying drawings,
Figure 1 illustrates an existing electromechanical switch.
Figures 2 and 3 illustrate an electromechanical switch assembly according to an
embodiment of the present invention.
Figure 4 illustrates a housing of an electromechanical switch according to an
embodiment of the present invention.
Figure 5(a)-(b) illustrates an isometric view of magnet sub assembly the
electromechanical switch according to an embodiment of the present invention.
Figure 5(c) illustrates an isometric view of magnet sub assembly of the
electromechanical switch according to an alternate embodiment of the present
invention.
Figure 6(a) and 6(b) illustrate sectional view of electromechanical switch assembly
according to embodiments shown in Figures 5(a) and 5(c), respectively.
Figures 7-9 illustrate a magnet sub assembly of the electromechanical switch
according to an embodiment of the present invention.
Figure 10 shows tilting of actuating shaft in an electromechanical switch assembly
according to another embodiment of the present invention.
Figure 11 shows a sectional view depicting relative dimensions of guiding tracks
and projections in an electromechanical switch assembly according to another
embodiment of the present invention
Figure 12 illustrate the assembly sequence of magnet sub assembly according to an
embodiment of the present invention.
Figure 13 depicts the sectional view of an electromechanical switch assembly
according to another embodiment of the present invention.
.
Figures 14and 15 illustrate actuation of electromechanical switch of the present
invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
5
While the invention is susceptible to various modifications and alternative forms,
specific embodiment thereof has been shown by way of example in the figures
and will be described in detail below. It should be understood, however that it is
not intended to limit the invention to the particular forms disclosed, but on the
contrary, the invention is to cover all modifications, equivalents, and alternative
falling with in the spirit and the scope of the invention as defined by the appended
claims.
Before describing in detail the various embodiments of the present invention it
may be observed that the novelty and inventive step that are in accordance with the
present invention resides in the construction of electromechanical switch. It is to be
noted that a person skilled in the art can be motivated from the present invention
and modify the various constructions of electromechanical switch. However, such
modification should be construed 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 benefit of the description herein.
The terms “comprises”, “comprising”, “including” or any other variations thereof,
are intended to cover a non-exclusive inclusion, such that an assembly,
mechanism, setup, that comprises a list of components does not include only those
components but may include other components not expressly listed or inherent to
such assembly, mechanism or setup. In other words, one or more elements in
turn indicator control switch or assembly proceeded by “comprises” does not,
without more constraints, preclude the existence of other elements or additional
elements in the assembly or mechanism. The following paragraphs explain
present invention and the same may be deduced accordingly.
6
Accordingly, it is an aim of the present invention to address at least one of the
problems associated with the prior existing switches.
Accordingly, the present invention provides an electromechanical switch
comprising:
a casing comprising a hollow region and adapted to receive a housing;
a housing comprising;
an exterior and an interior having a hollow region, defined by a
bottom wall, a top wall, two opposite side walls, a closed end wall and an
open end;
a first guide track formed on the side walls of the housing,
extending longitudinally between the open end and the closed end wall of
the housing;
a second guide track formed on the bottom wall of the housing,
extending longitudinally between the open end and the closed end wall of
the housing;
a magnet sub-assembly accommodating a magnet disposed in the interior of
the housing under the force of a spring and movable along a longitudinal
direction; and comprising;
a plurality of projections extending laterally towards the opposite
side walls and the bottom wall of the said housing;
the said projections being received in the first and second guiding
tracks thereby slidably supporting the magnet sub-assembly and restricting
the movement of the magnet subassembly in lateral direction;
an actuating shaft has a proximal end being disposed in the interior of the
housing so as to remain in contact with the magnet sub-assembly; and a
distal end operatively coupled with brake pedal so that movement of the
brake pedal causes actuation of the actuating shaft thereby allowing
7
movement of the spring loaded magnet sub-assembly in longitudinal
direction;
a PCB assembly accommodated in the housing; the PCB assembly
comprises one or more Hall sensors adapted to detect change in magnetic
flux due to movement of the magnet sub-assembly and to provide signal
indicative of activation of brake light, cruise control etc.
In an embodiment of the present invention a clearance is provided between the
plurality of projections received in the first guide track and the opposite side walls
of the housing.
In another embodiment of the present invention the magnet sub assembly is a
modular type assembly comprising an adapter and a socket accommodating a
magnet.
In still another embodiment of the present invention the magnet sub assembly
comprises a socket being removably mounted on the adapter.
In yet another embodiment of the present invention the spring is accommodated in
a cylindrical hole formed in the adapter and the said spring is located on a locating
pin formed in the housing.
In another embodiment of the present invention the proximal end of the actuating
shaft has a curved surface which remains in point contact with the magnet subassembly.
In a further embodiment of the present invention 3 curved faces formed on the
projections of magnet subassembly and 3 mating faces of the side wall of the guide
tracks of housing are adapted to restrict clockwise play of the magnet sub assembly
about the longitudinal direction.
8
In a further more embodiment of the present invention 3 curved faces formed on
the projections of magnet subassembly and corresponding 3 mating faces of the
side wall of the guide tracks of housing are adapted to restrict anti clockwise play
of the magnet sub assembly about the longitudinal direction
The following description describes the present invention with reference to Figures
2 to 12 according to an embodiment of the present invention.
Figures 2 and 3 illustrate an electromechanical switch assembly (1) according to an
embodiment of the present invention. Referring to Figures 2 and 3, the
electromechanical switch assembly (1) 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)
accommodating a magnet (30), a spring (6), a PCB sub assembly (7).
As shown in figure 3, the casing (2) has 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 (1). 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).
The term ‘proximal end’ herein refers to an end of the shaft which is nearer to the
magnet sub-assembly. The term ‘distal end’ herein refers to an end of the shaft
9
which is located far from the magnet sub-assembly as compared to the proximal
end.
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). The proximal end (13) is a rim shaped structure. The rim shaped
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
12). 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 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 and deactivation of cruise control etc.
Figure 4 illustrates a housing (3) of an electromechanical switch (1) 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 4, the
housing (3) comprises an exterior (3a) and an interior (3b). The interior (3b) of the
housing (3) is defined by a hollow region (15) delineated by a bottom wall (16), a
10
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) for slidably supporting the magnet sub assembly (5). As shown in Figure
4, each of the guiding tracks comprises two side wall (W) and an end wall (We).
As shown in Figure 3, a first guide track (22) is formed on the opposite side walls
(18, 19) of the housing. The said first guide track (22) extends longitudinally
between the open end (20) and the closed end wall (21) in the interior (13b) of the
housing (3). A second guide track (23) is formed on the bottom wall (16) of the
housing (3) and extends longitudinally between the open end (20) and closed end
wall (21) in the interior (13b) of the housing (3).
Referring to Figure 4, the housing (3) is provided with a locating pin (24)
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). The
slots (25) are sized to accommodate the PCB sub assembly (7). A plurality of
apertures (26) is provided on the closed end wall (21) for projecting there through
the terminals of the PCB sub assembly (7) for electrical connection. 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 (1).
Figure 5(a) illustrates an isometric view of the magnet sub assembly (5). As shown
in the figure 5(a), the magnet sub assembly (5) is a rigid structure comprising side
faces (33, 34), a bottom face (35) and an upper face (36). A plurality of projections
(44, 45) is formed on the magnet sub assembly (5) for slidably supporting the
magnet sub assembly (5) on the guiding tracks (22, 23) formed in the housing (3).
Referring to Figures 5(a) and 5(b), the magnet sub assembly (5) comprises an
adapter (28) and a socket (29) accommodating a magnet (not shown in Figure 5).
11
In an embodiment, the magnet (as shown in Figure 3) is a rectangular magnet. The
socket (29) is a rigid structure having a slot (31) being sized to removably receive a
magnet (30). The adapter (28) comprises a cavity (37) adapted to receive the
socket (29). The socket (29) can be secured with the adapter (28).
In an embodiment of the present invention, the plurality of projections (44, 45)
comprises primary projections (44) extending laterally from the side faces (33, 34)
of the magnet sub assembly (5) and one or more secondary/auxiliary projections
(45) extending laterally from the bottom face (35) of the magnet sub assembly (5).
The term “lateral” herein refers to a direction perpendicular to the longitudinal
direction in a plane perpendicular to the plane of the side walls.
As shown in Figure 5(c), the magnet sub assembly may be provided with a pair of
primary projections (440) and a secondary/auxiliary projection (450) for slidably
supporting the magnet sub assembly (5) on the guiding tracks (22, 23).
In another embodiment of the present invention, the magnet sub assembly (5) may
be formed by insert molding and the magnet (30) may be insert-molded in the
magnet sub assembly (5). Thus, the magnet sub assembly (5) may be a singular
rigid structure without having a modular construction.
As shown in Figure 5(a)-(b), the primary projections (44) are formed on the side
faces (33, 34) of the magnet sub assembly (5). The primary projections (44) extend
longitudinally along the length of side faces (33, 34) of the magnet sub assembly
(5). The primary projections (44) project laterally, towards the opposite side walls
(18, 19) of the housing (3) and are received in the first guiding tracks (22) so as to
slidably support the magnet sub assembly (5) in the longitudinal direction (as
shown in figure 6). The primary projections (44) have a first end (44a) and a
second end (44b). The first end (44a) can be located near or at the side faces (33,
34) of the magnet sub assembly (5). The second end (44b) of the primary
projections (44) is located away from the side faces (33, 34) of the magnet sub
12
assembly (5) and has curved surface so as to enable line contact with the side walls
(W) of guide tacks when received in the first guiding tracks (22) thereby reducing
the surface area of contact between the primary projections (44) and first guiding
tracks (22) resulting in less friction on movement of the magnet sub assembly (5)
in the longitudinal direction.
The secondary/auxiliary projections (45), as shown in figure 5, are formed on the
bottom face (35) of the magnet sub assembly (5). The secondary/auxiliary
projections (45) extend longitudinally along the length of the bottom face (35) of
the magnet sub assembly (5) and project laterally at a certain predefined angle
from the bottom face (35), towards the bottom wall (16) in the interior (3b) of the
housing (3). The secondary/auxiliary projections (45) are received in the second
guide track (23) so as to support the magnet sub assembly (5) in the lateral
direction (as shown in figure 6). The secondary/auxiliary projections (45) have a
first end (45a) and a second end (45b). The first end (45a) of the
secondary/auxiliary projections (45) can be located near or at the bottom face (35)
of the magnet sub assembly (5). The second end (45b) of the secondary/auxiliary
projections (45) is located away from the bottom face (35) of the magnet sub
assembly (5) and has a curvature formed so as to enable line contact with the side
walls (W) of the second guide track (23) when received in the second guide track
(23) thereby reducing the surface area of contact between the secondary/auxiliary
projections (45) and second guide track (23) and restricting lateral sideways
movement of the magnet sub assembly (5) and thus preventing lateral
misalignment of the magnet (30) with respect to the hall sensors in the PCB
assembly (7).
As shown in Figure 5(b), the six curves surfaces are formed on second ends of
primary and secondary/auxiliary projections. The said curved surfaces are formed
highly smooth finish for minimum friction and facilitating smooth movement of
the magnet sub assembly in the guiding tracks.
13
Figure 6(a) and 6(b) illustrates a sectional view of the electromechanical switch (1)
according to embodiments shown in Figures 5(a) and 5(c). Referring figures 6(a)
and 6(b), a cylindrical hole (43) is formed on the face of the magnet sub assembly
(5) that faces the closed end wall (21) when disposed in the housing (3). The
cylindrical hole (43) is sized to accommodate the spring (6) located on the locating
pin (24) formed in the interior (3b) of the housing (3).
As shown in figure 6(a), the primary projections (44) are received in the first
guiding tracks (22) so as to slidably support the magnet sub assembly (5) in the
interior (3b) of the housing (3). The second end (44b), due to its curvature, forms
line contact with the first guiding tracks (22). This reduces friction between the
mating parts and enables smooth movement of the magnet sub assemble (5) in the
longitudinal direction. A first clearance (c1) is provided between the second end
(44b) of the primary projections (44) and the end wall (We) of the first guiding
tracks (22). The first clearance (c1) is provided to address the problem of
dimensional inaccuracy while manufacturing small parts.
Referring to figure 6(a), the secondary/auxiliary projections (45) are received in
the second guiding track (23) so as to support the magnet sub assembly (5) in the
lateral direction. The secondary/auxiliary projections (45) subtend at an angle from
the bottom face (35) of the magnet subassembly such that the horizontal distance
between the second ends (45b) is more than the distance between first ends (45a)
of the corresponding secondary/auxiliary projections (45). The second end (45b),
due to its curvature, forms line contact with the side walls (W) of the second tracks
(23). This reduces friction between the mating parts and enables smooth movement
of the magnet sub assembly (5) in the longitudinal direction. Also, the
secondary/auxiliary projections (45) restrict the lateral sideways movement of the
magnet sub assembly (5) to prevent misalignment of the magnet (30) with the hall
sensors of the PCB assembly (7). A second clearance (c2) is provided between the
second end (45b) of the secondary/auxiliary projections (45) and the end wall (We)
of the second guiding track (23). The clearance (c2) ensures no contact between
14
the secondary/auxiliary projections (45) and the end wall (We) of the second
guiding track (23). This further facilitates smooth movement of the magnet sub
assembly (5) in the longitudinal direction.
It can be clearly understood from Figure 6(a), clockwise play of the magnet sub
assembly is restricted/arrested by 3 curved faces formed on the projections of
magnet subassembly and 3 mating faces of the side wall of the guide tracks of
housing. Also, anticlockwise play of the magnet sub assembly is restricted/arrested
by other 3 curved faces formed on the projections of magnet subassembly and
corresponding 3 mating faces of the side wall of the guide tracks of housing.
Moreover, 4 faces of side wall of first guiding tracks and corresponding 4 curved
surfaces of the primary projections restrict movement of magnet sub assembly in in
the direction of clearance (c2). Similarly, 2 faces of side wall of second guiding
tracks and corresponding 2 curved surfaces of the secondary/auxiliary projections
restrict movement of magnet sub assembly in the direction of clearance (c1).
As shown in Figure 6(b), A first clearance (c3) is provided between the second end
(440b) of the primary projections (440) and the end wall (We) of the first guiding
tracks (22). The first clearance (c3) is provided to address the problem of
dimensional inaccuracy while manufacturing small parts. A second clearance (c4)
is provided between the second end (450b) of the secondary/auxiliary projections
(450) and the end wall (We) of the second guiding track (23). The clearance (c4)
ensures no contact between the secondary/auxiliary projections (450) and the end
wall (We) of the second guiding track (23).
Figures 7-9 illustrate a magnet sub assembly (5) of the electromechanical switch
(1) according to an embodiment of the present invention. The present invention
provides an arrangement for solving misalignment problem of magnet sub
assembly in the guiding tracks of the housing resulting in poor switching accuracy.
Figure 7a represents the top view, Figure 7b represents the side view and 7c
represents the bottom view of a stop lamp or electromechanical switch assembly.
15
Further section A-A as depicted in Figure 8 and Figure 9 represents the position of
shaft in case of no switching condition and switching condition i.e. when shaft is
completely outwards and when shaft is completely inwards by actuation of break
pedal of the said vehicle. As shown in Figure 10, problem of switching point
inaccuracy due to tilting of shaft because of sliding clearance available between
shaft and casing is also addressed/solved by splitting of shaft with sliding part of
prior art into two components as shaft and magnet sub assembly. The actuating
shaft is free to slide in casing part and the other part i.e. magnet sub assembly is
free to reciprocate in the specially designed at least three guiding tracks provided
in housing and projections in the magnet sub assembly. These projections and
guiding tracks comprise sliding clearance between the both so as to smoothly
reciprocating operation of magnet sub assembly smoothly. As shown in figure,
shaft comprises of convex shape and magnet sub assembly mating face comprises
of flat face so as to form point contact between both the parts.
Furthermore, referring to Figure 11. length of the first and second guiding tracks
(u+v) is greater than required length of the magnet sub assembly after completing
full stroke i.e. (v+ full switching stroke) should be less than or equal to (v+u) in
order to ensure more than 100% engagement of the projections of magnet sub
assembly in guiding tracks of housing for furnishing accurate sliding without
tilting of slider in housing.
Figures 12 shows magnet sub assembly and depicts the sequence of assembling the
magnet sub-assembly according to an embodiment of the present invention. As
shown in Figure 10, the magnet (30) is first inserted in the slot (31) of the socket
(29) and thereafter, the socket (29) is mounted in the cavity (37) on the adapter
(28) to form the magnet sub-assembly (5).
16
In another embodiment of the present invention, the magnet sub assembly (5) may
be formed by insert molding and the magnet (30) may be insert-molded in the
magnet sub assembly (5). Thus, the magnet sub assembly (5) may be a singular
rigid structure without having a modular construction.
As described in previous paragraphs, mating faces of the projections in magnet sub
assembly can be curved and mating faces of the corresponding guiding tracks may
be flat in order to achieve line contact at four places. When magnet sub assembly
reciprocates, achieved line contact will reduce the frictional force between guiding
tracks and the magnet sub assembly and guiding tracks in the housing.
Referring to Figure 13, dimensions k, l, m, n, o and p may be selected in such a
way that there is close sliding clearance between the magnet sub assembly and
guiding tracks. Said close sliding clearance may be achieved by keeping clearances
(k-n), (l-o) and (m-p) to be in the range of 0.08mm ~ 0.2mm maximum. Further,
clearances (q-r) and (t-s) may be selected in such a way that there is enough
clearance between the magnet sub assembly and guiding tracks. The said clearance
may be in the range of 0.5mm to 0.7 mm so that in any condition during sliding or
reciprocating of magnet sub assembly in housing, faces a, b, c & d are not touching
e, f, g and h respectively. Achieved clearance also facilitates easy assembly of
magnet sub assembly in housing during switch assembly process.
Furthermore, dimensions k, l, m, n, o & p may be manufactured in close tolerance
of 0.03mm ~0.06mm with special tool manufacturing processes in order to
minimize the sliding clearance. Also this is important to note that for achieving
above said close tolerance, external surfaces of dimensions k, l, m, n, o & p may be
kept smooth by keeping tool highly polished and without known molding defect
during molding of magnet sub assembly and housing.
Figures 14 and 15 illustrate actuation of electromechanical switch (1) of the
present invention. As depicted in figure 11, the electromechanical switch is in non17
actuated condition. In the non-actuated condition, 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 of the actuating shaft so as to apply a force
on the distal end (14) of the shaft (4) when the brake pedal is in released position.
In this position, 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 (1). When the brake pedal is pressed or an
external force is applied on the brake pedal, the force applied on the distal end (14)
of the shaft by the brake pedal getting released. This is non-actuated condition of
the switch.
Referring to Figure 15, when the force of the brake pedal on the distal end (14) is
removed, the spring (6) expands and pushes the magnet sub assembly (5) thereby
resulting in a sliding movement of the magnet sub assembly (5) on the guiding
tracks (22, 23). Movement of the magnet sub assembly (5) pushes the first curved
surface (13a) of the actuation shaft (4) in longitudinal direction. In this position the
second flat surface (13b) abuts with the stopping face (10a) of the rear end wall
(10) of the casing (2) to restrict further movement of the actuation shaft (4). This is
the actuated condition of the said electromechanical switch.
18
We claim:
1. An electromechanical switch comprising:
a casing comprising a hollow region and adapted to receive a housing;
a housing comprising;
an exterior and an interior having a hollow region, defined by a
bottom wall, a top wall, two opposite side walls, a closed end wall and an
open end;
a first guide track formed on the side walls of the housing,
extending longitudinally between the open end and the closed end wall of
the housing;
a second guide track formed on the bottom wall of the housing,
extending longitudinally between the open end and the closed end wall of
the housing;
a magnet sub-assembly accommodating a magnet disposed in the interior of
the housing under the force of a spring and movable along a longitudinal
direction; and comprising;
a plurality of projections extending laterally towards the opposite
side walls and the bottom wall of the said housing;
the said projections being received in the first and second guiding
tracks thereby slidably supporting the magnet sub-assembly and restricting
the movement of the magnet subassembly in lateral direction;
an actuating shaft has a proximal end being disposed in the interior of the
housing so as to remain in contact with the magnet sub-assembly; and a
distal end operatively coupled with brake pedal so that movement of the
brake pedal causes actuation of the actuating shaft thereby allowing
19
movement of the spring loaded magnet sub-assembly in longitudinal
direction;
a PCB assembly accommodated in the housing; the PCB assembly
comprises one or more Hall sensors adapted to detect change in magnetic
flux due to movement of the magnet sub-assembly and to provide signal
indicative of activation of brake light, cruise control etc.
2. An electromechanical switch as claimed in claim 1, wherein the spring
received in a groove located on the side face of the magnet sub assembly which
faces the closed end wall of the housing.
3. An electromechanical switch as claimed in claim 1, wherein the plurality of
projections comprises primary projections extending laterally from the side faces
of the magnet sub assembly and one or more secondary/auxiliary projections
extending laterally from the bottom face of the magnet sub assembly.
4. An electromechanical switch as claimed in claim 3, wherein;
the primary projection comprises;
a first end located near or at the side faces of the magnet sub
assembly; and
a second end located away from the side faces of the magnet
sub assembly and having a curved surface; and
the secondary/auxiliary projection comprises;
a first end located near or at the bottom face of the magnet
sub assembly; and
a second end located away from the bottom face of the
magnet sub assembly and having a curved surface.
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5. An electromechanical switch as claimed in claims 1 and 3, wherein the said
projections are received in the first and second guiding tracks thereby slidably
supporting the magnet sub-assembly by forming line contact between the primary
and secondary/projections and the corresponding first and second guiding tracks.
6. An electromechanical switch as claimed in claims 1 and 3, wherein the
secondary/auxiliary projections is received in the second guiding tracks and
restricts the movement of the magnet subassembly in lateral direction.
7. An electromechanical switch as claimed in claims 1 and 3, wherein a first
clearance is provided between the primary projections received in the first guide
track and end wall of the first guiding track.
8. An electromechanical switch as claimed in claims 1 and 3, a second
clearance is provided between the secondary/auxiliary projections received in the
second guiding track and end wall of the second guiding track.
9. An electromechanical switch as claimed in claim 3, wherein the second
guiding track receiving one or more secondary/auxiliary projections, slidably
supports the magnet sub assembly in the longitudinal direction and restricts its
movement in the lateral direction.
10. The electromechanical switch as claimed in claim 1, wherein the proximal
end of the actuating shaft has a curved surface which remains in point contact with
the magnet sub-assembly.
11. The electromechanical switch as claimed in claim 1, wherein the magnet
sub assembly comprising an adapter and a socket accommodating a magnet;
the socket being adapted to be fitted in a corresponding cavity in the
adapter;
the adapter, comprising a cavity to receive the socket.
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12. The electromechanical switch as claimed in claim 1, wherein the magnet
sub assembly may be formed by insert molding; and the magnet being insertmolded
in the magnet sub assembly.
13. The electromechanical switch as claimed in claim 1, wherein 3 curved
faces formed on the projections of magnet subassembly and 3 mating faces of the
side wall of the guide tracks of housing are adapted to restrict clockwise play of the
magnet sub assembly about the longitudinal direction.
14. The electromechanical switch as claimed in claim 1, wherein 3 curved
faces formed on the projections of magnet subassembly and corresponding 3
mating faces of the side wall of the guide tracks of housing are adapted to restrict
anti clockwise play of the magnet sub assembly about the longitudinal direction.