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 ON/OFF of 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 are widely used in automobiles for
switching (ON/OFF) various functions such as stop lamp function, cruise control
function, etc. In contactless switches, one or more magnets are essentially required
to deliver sufficient magnetic flux density to sensing element such as hall element
or magneto resistive element or the like.
In the existing method, the magnetic part without magnetization is first assembled
with the moving part by insert molding and thereafter magnetization is performed
of the magnetic material. This process requires special purpose magnetization
machines and tedious process control for magnetic properties and also a huge
investment on equipment and operating cost.
JP5194860 describes a method of magnet assembly with moving part wherein a
magnet is snap locked directly with the moving part made of insulating resin. The
locking of magnet is performed with a single lock only and further for the said lock
to be flexible enough, both side of snap have been relieved and furthermore
relieving height is more than half of the magnet length. In this case magnet will be
press fitted in the three internal sides of the magnet holding part. This leads to
weak holding of magnet in moving part.
The problem with this type of method of magnet assembly with moving part is
tilting of the magnet towards the snap lock due to flexibility of snap lock which
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provides less support to magnet with the wall aligning to snap lock due to height
relief of that wall both side of snap lock. When magnet is tilted, it leads to
insufficient magnetic flux to the sensor or hall element resulting in variation in
switching point.
Another problem with this existing method of magnet assembly with moving part
is that lock overlapping between lock and magnet is very small so as to hold the
magnet firmly. This locking is between magnet having smooth surface and moving
part (slider) having smooth finish. The said single lock provided herein can slide
over the smooth surface of magnet under peak vibration condition and locking
between the magnet and moving part can be partially or completely damaged
resulting in the magnet falling down due to severe vibration condition. Thus, the
prime function of said switch assembly would have failed.
SUMMARY OF THE INVENTION
The present invention provides an electromechanical switch comprising a casing
comprising a hollow region and adapted to receive 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 resiliently loaded magnet
sub-assembly accommodating a magnet disposed in the housing under a force of a
spring, being slidably supported on one or more guiding tracks formed in the
interior of the housing. The magnet sub assembly comprising an adapter and a
socket accommodating a magnet. The socket is adapted to be fitted in a
corresponding cavity in the adapter. The adapter comprising a cavity to receive the
socket and a plurality of projections extending laterally towards the opposite side
walls and the bottom wall of the 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
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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 and deactivation of 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
the scope of the invention. In the accompanying drawings,
Figures 1 and 2 illustrate an electromechanical switch assembly according to an
embodiment of the present invention.
Figure 3 illustrates a housing of an electromechanical switch according to an
embodiment of the present invention.
Figures 4-7 illustrate a magnet sub assembly of the electromechanical switch
according to an embodiment of the present invention.
Figure 8 illustrates the assembly sequence of magnet sub assembly according to an
embodiment of the present invention.
Figure 9 illustrates sectional view taken along a plane parallel to and at some
distance from rear end wall of the electromechanical switch.
Figures 10 and 11 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.
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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 a electromechanical switch
comprising:
a casing comprising a hollow region and adapted to receive a housing;
a 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 resiliently loaded magnet sub-assembly accommodating a magnet
disposed in the housing under a force of a spring, being slidably supported
on one or more guiding tracks formed in the interior of the housing; the
magnet sub assembly comprising a 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 and a plurality
of projections extending laterally towards the opposite side walls and the
bottom wall of the housing;
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
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.
7
In an embodiment of the present invention the magnet is accommodated in a slot
formed in the socket wherein the slot for receiving the magnet may be partially
open from upper side when in mounted condition for saving material and reducing
cost of component.
In yet another embodiment of the present invention the magnet is accommodated
in a slot formed in the socket wherein the slot for receiving the magnet may be
covered from upper side when in mounted condition by an upper covering portion
for preventing entry of contaminants like dust, water and humidity, thereby
enhancing life of component.
In another embodiment of the present invention the socket is provided with a
projection adapted to be received in a corresponding cutout formed on the adapter,
for ensuring correct orientation of the socket on the adapter.
In still another embodiment of the present invention the magnet sub assembly is
disposed in the housing under a force of a spring.
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 a further embodiment of the present invention the magnet is a rectangular
magnet.
In a further more embodiment of the present invention the slot is provided with one
or more crushing rib for snugly accommodating the magnet therein.
In another embodiment of the present invention the cavity of the adapter is
provided with mating ribs to firmly constrain the socket in the cavity in the
mounted condition.
8
In still another embodiment of the present invention a first guide track is formed on
the side walls of the housing, extending longitudinally between the open end and
the closed end wall of the housing; and 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;
In one more embodiment of the present invention the magnet sub assembly is
slidably supported on the first and second guide tracks by means of a plurality of
projections extending laterally towards the opposite side walls and the bottom wall
of the said housing.
The following description describes the present invention with reference to Figures
1 to 10 according to an embodiment of the present invention.
Figures 1 and 2 illustrate an electromechanical switch assembly (1) according to an
embodiment of the present invention. Referring to Figures 1 and 2, 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),
a spring (6), a PCB sub assembly (7).
As shown in figure 2, 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
9
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
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 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 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.
10
Figure 3 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 3, 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
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
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 3, 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).
Figures 4-7 illustrate a magnet sub assembly (5) of the electromechanical switch
(1) according to an embodiment of the present invention.
Referring to Figures 4-8, the magnet sub assembly (5) comprises an adapter (28)
and a socket (29) accommodating a magnet (30). In an embodiment, the magnet
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(30) is a rectangular magnet. The socket (29) is a rigid structure having a slot (31)
being sized to removably receive a magnet (30). The slot (31) is provided with one
or more crushing ribs (32) to snugly hold the magnet (30) in the slot (31).
The adapter (28) is a rigid structure comprising side faces (33, 34), a bottom face
(35) and an upper face (36). The upper face (36) is provided with a cavity (37)
adapted to receive the socket (29). In an embodiment, mating ribs (38) are formed
in the cavity (37) so as to firmly constrain the socket (29) in the cavity (37) in the
mounted condition. The socket (29) can be secured with the adapter (28). For this
purpose, a plurality of snaps (39) is provided on outer periphery of the socket (29)
for facilitating mounting of the socket (29) on the adapter (28). A plurality of side
locks (40) may be formed on the periphery of the upper face (36) to receive the
corresponding snaps (39) provided on the socket (29).
In an embodiment, a projection (41) is formed on the socket (29) extending
laterally outwardly from the socket (29). The term “lateral” herein refers to a
direction perpendicular to the longitudinal direction in a plane perpendicular to the
plane of the side walls; and a corresponding cutout (42) is formed on the upper
face (36) of the adapter (28) for receiving the projection (41) of the socket (29) to
ensure correct orientation of socket (29) when mounted on adapter (28).
In yet another embodiment of the present invention, as shown in figures 6 and 7,
the slot (31) for receiving the magnet (30) may be covered from upper side when in
mounted condition by an upper covering portion (cu). The thickness of the upper
covering portion (cu) may vary between 0.4mm and 0.6mm. The upper covering
portion (cu) may protect the magnet (30) in the slot (31) from dust, water, humidity
and other contaminants when in the mounted condition.
Figure 8 depicts the sequence of assembling the magnet sub-assembly wherein the
magnet (30) is first inserted in the slot (31) of the socket (29). The socket (29) is
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then mounted in the cavity (37) on the adapter (28) to form the magnet subassembly.
Referring to figure 8 in a further embodiment, the upper covering portion (cu) may
be avoided on the slot (31) for the purpose of saving cost in respect of extra
material used in the upper covering portion (cu).
Figure 9 illustrates a sectional view of the electromechanical switch along a plane
parallel to and at some distance from rear end wall of the electromechanical
In an embodiment, a plurality of projections (44, 45) is formed on the adapter (28)
for slidably supporting the magnet sub assembly (5) on the guiding tracks (22, 23)
formed in the housing (3).
The plurality of projections (44, 45) comprises primary projections (44) extending
laterally from the side faces of the adapter (28). As shown in Figure 9, the primary
projections (44) on the side faces of the adapter (28) laterally extend towards the
opposite side walls (18, 19) in the interior of the housing (3) and are received in the
first guide tracks (22) so as to slidably support the magnet sub assembly (5) in the
longitudinal direction. Referring to figures 8 and 9, one or more
secondary/auxiliary projections (45) are formed on the bottom face of the adapter
(28) which extends towards the bottom wall (16) in the interior (3b) of the housing
(3). The secondary/auxiliary projections (45) being received in the second guide
track (23) and provide support to the magnet sub assembly (5) in the lateral
direction.
Figures 10 and 11 illustrate actuation of electromechanical switch (1) of the
present invention. As depicted in figure 10, the electromechanical switch is in nonactuated
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.
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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 or no
switching condition of the switch.
Referring to Figure 11, when the brake pedal is pressed, 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 or switching condition of
the said electromechanical switch.
ADVANTAGES OF THE PRESENT INVENTION
1. In the present invention the magnet in the magnet sub assembly is kept
protected from dust, water and other contaminations. Thus enhancing
work life cycle of the said electromechanical switch.
2. One more advantage of the present invention is that the magnet in the
magnet sub assembly is not in direct contact with surrounding
temperature conditions protecting the magnet from the adverse effects
of humidity on the magnet’s mechanical and magnetic properties.
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3. Yet another advantage of the present invention is that the magnet can be
easily mounted on the magnet sub assembly enhancing the
serviceability of the said electromechanical switch.
4. Furthermore, an advantage of the present invention is the firm assembly
of the magnet with the adapter of the magnet sub-assembly.
15
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, defined by a bottom wall,
a top wall, two opposite side walls, a closed end wall and an open end;
a resiliently loaded magnet sub-assembly accommodating a magnet
disposed in the housing under a force of a spring, being slidably supported
on one or more guiding tracks formed in the interior of the housing; the
magnet sub assembly comprising a 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 and a plurality
of projections extending laterally towards the opposite side walls and the
bottom wall of the housing;
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
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.
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2. An electromechanical switch as claimed in claim 1, wherein the magnet is
accommodated in a slot formed in the socket.
3. An electromechanical switch as claimed in claims 1 and 2, wherein the slot
for receiving the magnet may be partially open from upper side when in mounted
condition.
4. An electromechanical switch as claimed in claims 1 and 2, wherein the slot
for receiving the magnet may be covered from upper side when in mounted
condition by an upper covering portion.
5. An electromechanical switch as claimed in claim 1, wherein the socket is
provided with a projection adapted to be received in a corresponding cutout formed
on the adapter, for ensuring correct orientation of the socket on the adapter.
6. An electromechanical switch as claimed in claim 1, wherein the magnet sub
assembly is disposed in the housing under a force of a spring.
7. An electromechanical switch as claimed in claims 1 and 4, wherein 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.
8. An electromechanical switch as claimed in claim 1, wherein the magnet is a
rectangular magnet.
9. An electromechanical switch as claimed in claim 2, wherein the slot is
provided with one or more crushing rib for snugly accommodating the magnet
therein.
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10. An electromechanical switch as claimed in claim 1, wherein the cavity of
the adapter is provided with a mating ribs to firmly constrain the socket in the
cavity in the mounted condition.
11. An electromechanical switch as claimed in claim 1, wherein a first guide
track is formed on the side walls of the housing, extending longitudinally between
the open end and the closed end wall of the housing; and 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;
12. An electromechanical switch as claimed in claim 1, wherein the magnet sub
assembly is slidably supported on the first and second guide tracks by means of a
plurality of projections extending laterally towards the opposite side walls and the
bottom wall of the said housing.