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 sealing of a contactless electromechanical
switch assembly.
BACKGROUND OF THE INVENTION
Generally, electromechanical switch assemblies are widely being used in automobiles
for a long time for switching on and off any one or all the various 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 and 2. The
main problem with the prior art switches was that it becomes electrically non-operable
or failing to meet prime function of switching on and off of above said various
functions. Water entrapment in the switch may result in short circuiting of moving
and fixed contact and which may even lead to burning of contacts. This results into
failure of switch or reduction in switching life. Entrapment of water is shown in
Figure 1. Referring to Figure 1, fine dust entrapment in the switch occurs through the
paths indicated by arrows. This ingress of dust results in building up of a layer of dust
on the moving contact and/or fixed contact. Due to the layer of dust between contacts
introduces a friction between the contacts which results in slower contact separation
and leads to switch failure or reduction in switching life of the switch assembly..
Referring to Figure 2, a contactless stop lamp switch assembly is depicted wherein
due to water entrapment in the switch, sensor or other electronic components (which
are mounted on the printed circuit board) becomes wet and un-operable which leads
to switch failure or reduction in switching life of the switch assembly. Furthermore,
fine dust entrapment in the switch occurs through the paths indicated by arrows
results in accumulation of dust on sensor element. Due to the accumulated dust,
sensor’s sensitivity gets affected resulting in reduction in switching point accuracy of
switch assembly.
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SUMMARY OF THE INVENTION
An electromechanical switch comprising a housing comprising an interior and an
exterior, a casing comprising a hollow region adapted to receive the housing, a
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, 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 a sealing unit mounted on the
actuating shaft and adapted to provide sealing between the casing and the interior of
the housing 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.
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 existing contact type and contactless switch assembly.
Figures 3 and 4 illustrate a housing of an electromechanical switch assembly
according to an embodiment of the present invention.
Figures 5a-5d illustrate a sealing unit of the electromechanical switch assembly
according to an embodiment of the present invention.
Figures 6a-6d illustrate an actuating shaft of the electromechanical assembly switch
according to an embodiment of the present invention.
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Figures 7a-7b illustrates the non-actuated condition electromechanical switch
assembly of the present invention.
Figure 8 illustrates the actuation of electromechanical switch assembly of the present
invention.
Figure 9 illustrates an electromechanical switch assembly according to an alternative
embodiment of the present invention.
Figure 10 illustrates an electromechanical switch assembly according to an
embodiment of the present invention.
Figure 11 illustrates details of connector and housing in an electromechanical switch
assembly according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
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,
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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.
Accordingly, it is an aim of the present invention to overcome at least one of the
problem associated with the prior existing switches.
Accordingly, the present invention provides a electromechanical switch comprising:
a housing comprising an interior and an exterior;
a casing comprising a hollow region adapted to receive the housing;
a 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
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;
a sealing unit mounted on the actuating shaft and adapted to provide sealing between
the casing and the interior of the housing;
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.
In an embodiment of the present invention, the sealing unit comprises a flat portion
and a diaphragm portion formed on the flat surface.
6
In another embodiment of the present invention, the sealing unit is provided with
pockets for accommodating pluralities of crushing ribs formed in the interior of the
housing for securing the PCB sub assembly in a more accurate manner.
In still another embodiment of the present invention, the actuating shaft has an
annular seat at the proximal end for locating the diaphragm portion of the sealing unit.
In yet another embodiment of the present invention, the diaphragm portion has a first
annular end located at the flat portion and a second annular end opposite to the first
annular end and having an annular flange extending radially inwardly.
In yet another embodiment of the present invention, the flange portion of the
diaphragm is seated on the annular seat formed at the proximal end of the actuating
shaft.
In a further embodiment of the present invention, the diaphragm portion has a variable
thickness with thickness at the first annular end smaller than the thickness at the
second annular end so that the diaphragm portion can deform easily to actuated
condition and can return quickly to non-actuated condition.
In a further embodiment of the present invention, the sealing unit is positioned
between the housing and the stopping face of the casing.
In a further more embodiment of the present invention, the proximal end of the
actuating shaft has a curved surface which remains in contact with the magnet subassembly.
In a further more embodiment of the present invention, the actuating shaft has
plurality of ribs extending in longitudinal direction.
In still another embodiment of the present invention, the sealing unit is made up of
elastomeric material preferably rubber.
7
In one more embodiment of the present invention, the proximal end of the shaft
comprises an annular rim and an annular seat formed on the shaft and contiguous to
annular rim.
In still another embodiment of the present invention, the thickness of the flange
portion is higher than the thickness of the diaphragm portion of the sealing unit.
In one more embodiment of the present invention, the housing is provided with a
locating pin extending for locating the spring and a cylindrical hole may be formed on
the magnet sub assembly to accommodate the spring for resiliently mounting the
magnet sub assembly.
In another embodiment of the present invention, the proximal end of the shaft
comprises an annular rim and an annular seat formed on the shaft and contiguous to
annular rim;
In yet another embodiment of the present invention, the sealing unit comprises a
diaphragm portion having a flange portion which is seated on the annular seat.
In a further embodiment of the present invention, thickness of the flange portion is
higher than the thickness of the diaphragm portion of the sealing unit.
In a further more embodiment of the present invention, the actuating shaft has
plurality of ribs formed on the shaft extending in longitudinal direction.
In one more embodiment of the present invention, the said one or more ribs have
converging section extending from distal end towards the second annular rim at the
proximal end of the shaft.
Another embodiment of the present invention further comprising a connector
disposed in the housing, and mating face of the housing and the connector are
substantially flat in order to restrict dust and water ingress
8
In a further more embodiment of the present invention, a clearance between the
housing and the connector is provided so that the mating face of the housing and the
connector abut at butting face.
The following description describes the present invention with reference to Figures 1
to 10 according to an embodiment of the present invention.
Figures 3 and 4 illustrate an electromechanical switch assembly (1) according to an
embodiment of the present invention. Referring to Figures 3 and 4, 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 sealing unit (S), a magnet sub assembly
(5), a spring (6), a PCB sub assembly (7).
As shown in figure 4, 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 for forming
an encapsulation. The housing (3) and casing (2) can be made of any suitable material
preferably a thermoplastic material. The rear end wall (10) is incorporated with a
hollow cylindrical trough (12) extending perpendicularly and outwardly from the rear
end wall 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
9
(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
and remains in contact with the magnet sub assembly (5).
The term ‘proximal end (13)’ herein refers to an end of the shaft which is nearer to the
magnet sub-assembly (5). The term ‘distal end (14)’ herein refers to an end of the
shaft which is located far from the magnet sub-assembly (5) as compared to the
proximal end (13).
The magnet sub assembly (5) accommodates a magnet. The magnet sub assembly is
resiliently disposed in the housing (3) and adapted to move in a longitudinal direction
upon actuation by actuation shaft. For this purpose, the housing (3) is provided with
plurality of guiding tracks for slidably supporting the magnet sub assembly. The
housing (3) is provided with a locating pin (not shown in figure) extending towards
the open end from the rear end wall of the housing (3) for locating the spring (6) and a
cylindrical hole may be formed on the magnet sub assembly (5) to accommodate the
spring (6) for resiliently mounting the magnet sub assembly (5).
The PCB sub assembly (7) is accommodated in the housing (3) so as to be located
over the magnet sub assembly. For this purpose, the housing (3) is provided with slots
extending longitudinally between the open end (20) and closed end wall (21) are
formed on the side walls (18, 19). The slots are sized to accommodate the PCB sub
assembly (7). A plurality of apertures is provided on the closed end wall for
projecting there through the terminals of the PCB sub assembly (7) for electrical
connections with the driving circuit. 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, cruise control etc.
Exterior of the housing (3) is provided with one or more snaps adapted to cooperate
with the locking grooves provided on the casing for securing the housing (3) with the
casing to form an encapsulation.
10
Referring to Figure 4, the electromechanical switch assembly of the present invention
comprises a sealing arrangement/unit for providing sealing between the casing and
interior of the housing (3). Figures 5(a)-(c) illustrates a sealing arrangement/unit for
the electromechanical switch assembly according an embodiment of the present
invention.
The sealing unit (S) may be formed of any suitable elastomeric material such as
rubber. Referring to Figures 4 and 5a-5c, the sealing unit (S) has a flat portion (S1)
and a diaphragm portion (S2) formed on the flat portion (S1). The diaphragm portion
(S2) is a bell shaped portion. The flat portion (S1) of the sealing unit has a same shape
as the casing inner wall. The diaphragm portion (S2) of the rubber sealing has a first
annular end (S3) and a second annular end (S4). The first annular end (S3) of the
diaphragm portion (S2) is located at flat portion (S1) of the sealing unit (S). The
second annular end (S4) of the diaphragm (S2) is located opposite to the first end
(S3). The second annular end (S4) of the diaphragm portion (S2) having an annular
flange (S6) extending radially inwardly.
In an embodiment, the sealing unit (S) is provided with a plurality of rectangular
pockets (S5) formed on the flat portion (S2) of the sealing unit (S) for material
removal to reduce sealing weight.
The sealing unit (S) may be mounted on the shaft (4) preferably at the proximal end
(13) of the shaft (4). The shaft (4) may be made of any suitable plastic material.
Figures 6(a)-(d) illustrate a construction of the shaft (4) of electromechanical switch
assembly (1) according to an embodiment of the present invention.
Referring to Figures 4, 5(a)-(c) and 6(a)-(d), the proximal end (13) of the shaft has
two annular rims/flanges formed on the circumference of the actuating shaft (4). The
first annular rim/flange (13a) has a top curved surface which remains in contact with
the magnet sub assembly (5). The second annular flange/rim (13b) is located on the
shaft at spaced apart location in longitudinal direction from the first annular rim (13a).
An annular seat (13c) is formed in-between the first annular rim (13a) and the second
annular rim (13b) of the shaft (4) to accommodate the sealing unit (S). The flange
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portion (S6) of the diaphragm (S2) of the sealing unit (S) rests on the annular seat
(13c) formed on the proximal end (13) of the actuating shaft (4).
When diaphragm portion (S2) of the sealing unit (S) starts to actuate, the diaphragm
portion (S2) will tend to easily bend first from thinner wall starting at the base wall of
the sealing unit (S) and thicker wall section will exert opposite force and try to regain
its unactuated condition. When actuation force increases to the opposition force
exerted by the thicker wall, the diaphragm portion (S2) gets momentarily actuated.
Restoring force will be more at the thicker wall and thus diaphragm portion (S2) will
return to its initial condition quickly.
In top view (Figure 5b), outer profile is 0.1 to 0.2mm offset of the internal profile of
the casing (2) part so that rubber diaphragm can easily rest in the casing (2).
Referring to Figure 5c, vertical thickness t1 is kept to be 2~3mm so that it can be
compressed around 10% of its thickness during assembly with housing with the
intentional interference provided between the housing and casing part. Further, height
t2 is kept to be 4~7 mm depending upon the total compressed length of the rubber
diaphragm when shaft is actuated completed to switch on all the functions. Also,
section A-A has been disclosed to explain the constructional detail of flexible zone of
the rubber diaphragm. Diameter d1 has been kept as per the formula as d1>d2+4*t5
so that adequate sliding clearance remains for the movement of moving portion of the
rubber diaphragm.
Referring to Figure 5d, it represents the wall thickness design of the flexible portion
for expansion and contraction of during completion of switching stroke. Thickness t6
has been kept intentionally of smaller value than the thickness t7. The relation
between t6 and t7 has been established by conducting design of experiments and it is
t7>t6+0.4mm so that diaphragm has been supposed to be bent from t6 only. This
bending helps to regain the diaphragm to its original position (expanded) by virtue of
restoring force developed in the diaphragm as this restoring force is more at starting
from t7 due to more thickness and smaller at ending at t6 thickness due to lesser
thickness, t6 has been kept 0.4 to 0.6mm and t7 has been kept to be 0.7 to 0.9 mm.
12
Referring to Figures 6a-6d the actuating shaft (4) has plurality of ribs (16) formed on
the shaft (4) extending in longitudinal direction. The ribs (16) are formed in between
the second annular rim (13b) and the distal end (14) of the shaft. In an embodiment,
the one or more ribs (16) have converging section extending from distal end towards
the second annular rim (13b) at the proximal end (13) of the shaft. The converging
section reduces the area available for dust and water entry in the switch assembly (1)
which will reduce the possibility of dust and water entry to reach the face area of the
shaft in the switch assembly (1). Each of the ribs (16) tapers at the proximal end (13)
so as to form multiple inlets (or longitudinal grooves). In case of dust or water
accumulation of any assumed quantity near the second annual rim (13b), a greater
pressure head built up by the available trapezoidal volumes will expel the water and
dust towards outside automatically. When the shaft is received in the cylindrical
trough of the casing, the converging ribs forms diverging channels extending from the
distal end towards the second annular rim (13b) at the proximal end (13) of the shaft.
In other words, the size of the channel (i.e. the space between two ribs) increases as
we move from the distal end of the shaft towards the proximal end when the shaft is
received in the cylindrical trough of the casing. Therefore, the opening available for
entry of dust and water in the casing is very small. The large opening near in the
proximal end helps the accumulated water to exits from the casing through the said
channel. In an embodiment, the shaft comprises two converging ribs whose cross
section decreases as we move from distal end to the proximal end and two ribs
extending between the distal end and the proximal end whose cross section remains
constant.
Referring to Figures 7a and 7b, the sealing unit (S) can be positioned between casing
(2) and the housing (3). As shown in figure 7(a), the sealing unit (S) is positioned
between peripheral edges of side walls (18, 19) of the housing (3) and stopping face
(10a) of the rear end wall of the casing (2).
As can be observed from Figures 7(a) and 7(b), the annular seal formed on the shaft
acts as a holding groove for gripping the flange portion (S6) of the elastomeric sealing
unit. The said elastomeric sealing part is gripped in shaft holding groove or annular
seal due to the intentional interference provided between the both part diametrically.
The flat portion of the sealing unit is disposed between the peripheral edges of the
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housing (3) and the stopping face (10a) of the rear end wall of the casing. Thus, the
said elastomeric sealing unit is guided in all around the housing periphery. In order to
firmly restrict the movement of the sealing unit in longitudinal direction, side walls
(18, 19) of the housing (3) comprise an intentional interference between the side walls
(18, 19) and the sealing unit (S) guided or disposed in the casing (2). This
construction protects the switching parts for example magnet sub assembly (5), PCB
sub assembly (7) from water and dust.
Figure 8 illustrates actuation of electromechanical switch (1) of the present invention.
As depicted in figures 7(a) and 7(b), the electromechanical switch (1) is in nonactuated
or no switching 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 (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, In this position, the second annular rim (13b) of the proximal end (13) of the
actuation shaft (4) is not in contact with the stopping face (10a) of the rear end wall
(10) of the casing (2). The first annular rim (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 (4) by the brake pedal gets released.
Referring to Figure 8, 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.
Movement of the magnet sub assembly (5) pushes the actuation shaft (4) in
longitudinal direction. In this position the second annular rim (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 actuated or switching condition of the
said electromechanical switch. Further, as shown in Figure 8, when the shaft (4)
moves to the actuated position, the diaphragm portion (S2) of the sealing unit (S)
deforms. Referring to Figures 8 and 5(c), the first annular end (S3) forms a hinge
about which the diaphragm (S2) deforms. As shown Figure 5(c), the diaphragm
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portion (S2) has a variable thickness ratio with thickness at the first annular end (S3)
smaller than the thickness at the second annular end (S4) so that the diaphragm
portion (S2) can deform easily. The variable thickness ratio of the diaphragm portion
(S2) also provides quicker return of the diaphragm portion (S2) when the shaft (4)
moves back to the non-actuated condition.
Due to sudden abutment of the second annular rim (13b) with the stopping face (10a)
of the rear end wall (10) of the casing (2) generates noise. To avoid the same, in an
embodiment of the present invention, the sealing unit (S) and the shaft (40) may be
constructed to avoid contact between the second annular rim (13b) and the stopping
face (10a).
Referring to Figure 9, in an alternative embodiment, the proximal end (130) of the
shaft (40) comprises an annular rim (130a) and an annular seat (130c) formed on the
shaft (40) and contiguous to annular rim (130a). As shown in Figure 9, the annular
seat (130c) extends partially from the annular rim towards distal end (140) of the shaft
(40). The flange portion (S6) of the diaphragm portion (S2) of the sealing unit (S) has
been seated on the annular seat (130c). In an embodiment, thickness of the flange
portion (S6) is higher than the thickness of the diaphragm portion (S2) of the sealing
unit (S). It can be clearly understood from Figure 9, when the shaft (40) is actuated,
the flange portion (S6) of the sealing unit (S) comes in contact with the stopping face
(100a) and thus the noise which has been generated due to plastic to plastic contact is
avoided and/or reduced significantly.
Referring to Figure 10, according to an embodiment of the present invention,
intentional compression between PCB sub assembly (7) and sealing unit (S) is
provided which helps in improved assembly of PCB sub assembly (7) in housing (3)
in forms of firm assembly of PCB sub assembly (7) with casing (2) and housing (3).
There is cushioning provided by the rubber compression achieved through intentional
interference which is adding support to PCB assembly resting on crushing ribs. In
case of manufacturing defect in crushing ribs, height is smaller, sealing will provide
required support.
15
Referring to Figure 11, there is a possibility of dust and water ingress from connector
(22) side through the entry formed by clearances provides for the terminals to come
out from the housing (3). Therefore in an embodiment, mating faces (i.e. butting face)
of the housing (3) and connector (22) has been kept substantially flat in order to
restrict dust and water ingress. A clearance between the housing (3) and connector
may be provided so that the mating face of the housing and the connector can abut at
butting face (23).
Advantages of the present invention
(a) the main advantage of the present invention is that the it prevents the entry of dust
and water in the housing at two locations. As can be clearly observed that the the dust
and water can enter in the housing through the cylindrical trough and through the
junction of the housing and casing. The sealing unit in the present invention prevents
the entry of water and dust from these two locations. In other words, the sealing unit
forms a seal between the inner side of the rear end wall of casing and forms a seal
around the proximal end of the shaft which is received in a hollow cylindrical trough.
The sealing unit provide dust and water protection even when the shaft is
reciprocating or in motion. This protection increases the product life cycle.
(b) The present invention invention is much advantageous in case of vehicles which
are frequently washed by water jet pressure from the bottom side of the vehicle since
the possibility of water ingression inside the switch assembly is quite high during this
kind of washing.
(c) Another advantage of the present invention is that the sealing unit is constructed so
that the PCB assembly can be accommodated inside the housing and the actuation of
the diaphragm portion does not interfere with the other components disposed in the
housing.
(d) Yet another advantage is to dampen the operating noise generated due to plastic to
plastic contact, significantly.
16
We claim:
1. An electromechanical switch comprising:
a housing comprising an interior and an exterior;
a casing comprising a hollow region adapted to receive the housing;
a 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
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;
a sealing unit mounted on the actuating shaft and adapted to provide sealing between
the casing and the interior of the housing;
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.
2. The electromechanical switch as claimed in claim 1 wherein the sealing unit
comprises a flat portion and a diaphragm portion formed on the flat surface.
3. The electromechanical switch as claimed in claim 1 wherein the sealing unit is
provided with pockets for accommodating pluralities of crushing ribs formed in the
interior of the housing for the securing PCB sub assembly in a more accurate manner.
4. The electromechanical switch as claimed in claim 1, wherein the actuating
shaft has an annular seat at the proximal end for locating the diaphragm portion of the
sealing unit.
5. The electromechanical switch as claimed in claim 2 wherein the diaphragm
portion has a first annular end located at the flat portion and a second annular end
17
opposite to the first annular end and having an annular flange extending radially
inwardly.
6. The electromechanical switch as claimed in claim 5 wherein the flange portion
of the diaphragm is seated on the annular seat formed at the proximal end of the
actuating shaft.
7. The electromechanical switch as claimed in claim 5, wherein the diaphragm
portion has a variable thickness with thickness at the first annular end smaller than the
thickness at the second annular end so that the diaphragm portion can deform easily to
actuated condition and can return quickly to non-actuated condition.
8. The electromechanical switch as claimed in claim 1 wherein the sealing unit is
positioned between the housing and the stopping face of the casing.
9. The electromechanical switch as claimed in claim 1 wherein the proximal end
of the actuating shaft has a curved surface which remains in contact with the magnet
sub-assembly.
10. The electromechanical switch as claimed in claim 1, wherein the actuating
shaft has plurality of ribs extending in longitudinal direction.
11. The electromechanical switch as claimed in claim 1, wherein the sealing unit is
made up of elastomeric material preferably rubber.
12. The electromechanical switch as claimed in claim 1, wherein the proximal end of
the shaft comprises an annular rim and an annular seat formed on the shaft and
contiguous to annular rim.
13. The electromechanical switch as claimed in claim 12, wherein the thickness of the
flange portion is higher than the thickness of the diaphragm portion of the sealing
unit.
18
14. The electromechanical switch as claimed in claim 1, wherein the housing is
provided with a locating pin extending for locating the spring and a cylindrical hole
may be formed on the magnet sub assembly to accommodate the spring for resiliently
mounting the magnet sub assembly.
15. The electromechanical switch as claimed in claim 1, wherein the proximal end of
the shaft comprises an annular rim and an annular seat formed on the shaft and
contiguous to annular rim;
16. The electromechanical switch as claimed in claim 15, wherein the sealing unit
comprises a diaphragm portion having a flange portion which is seated on the annular
seat.
17. The electromechanical switch as claimed in claim 15, wherein thickness of the
flange portion is higher than the thickness of the diaphragm portion of the sealing
unit.
18. The electromechanical switch as claimed in claim 1, wherein the actuating shaft
has plurality of ribs formed on the shaft extending in longitudinal direction.
19. The electromechanical switch as claimed in claim 1, wherein the said one or more
ribs have converging section extending from distal end towards the second annular
rim at the proximal end of the shaft.
20. The electromechanical switch as claimed in claim 1, further comprising a
connector disposed in the housing, and mating face of the housing and the connector
are substantially flat in order to restrict dust and water ingress
21. The electromechanical switch as claimed in claim 20, wherein a clearance
between the housing and the connector is provided so that the mating face of the
housing and the connector abut at butting face.