Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
s~
FIELD OF THE INVENTION
This invention relates to inertia switches.
More particularly, this invention relates to an inertia
switch for activating the hazard lights of a vehicle upon impact
or severe deceleration.
BACKGROUND OF THE INVENTION
~ .. . . . . ~
In the event of motor vehicle accidents, it is desirable to
have automatic means for activating various safety features of
the vehicle. The same need arises in relation to other means of
transportation such as aircraft.
Canadian Patent 522,231, which issued February 28, 1986 to
the Pyree and Company, discloses an inertia switch for an
aircraft to provide for the autornatic activation and control of
apparatus such as fire extinguishers. The inertia switch of the
Pyree and Company patent comprises housing and contact surfaces
which are spaced a short distance apart under normal conditions.
One of the contact surfaces is in the shape of a disk. The other
contact surface is in the form a cup, which partly surrounds the
disk but does not touch it when the vehicle is at rest. The
contacts are carried on supports with differing moments of`
inertia such that under conditions of constant deceleration, the
contacts will not rneet, but in the event of higher differentials
~7~
-- 2 --
~f velocity, such as the case of a collision, the displacement of
the disk and the surrounding cup will vary with respect to one
another such that the disk will come into contact with the cup
thus establishing an electrical connection.
Canadian Patent 809,825 whic`n was issued April 1, 1969 to
Paonessa, discloses an inertia switch involving a heavy metal
ball and a spring. The metal ball is positioned within a metal
cage in an enclosure which extends parallel to the direction of
travel of the vehicle. A spring urges the metal cage towards the
rear end of the enclosure. An electrical contact is provided at
the forward end of the enclosure. Upon rapid deceleration such
as in the case of a co].lision, the forward inertia of the heavy
metal ball urges the cage forward against the spring and into
contact with the electrical contact thus activating a warning
systesn for any vehicles behind the decelerating vehicle.
Canadian Patent 998,138 issued October 5, 1976 to Nissan
Motor Company Limited discloses a trigger switch mechanisrn for
airbags in a vehicle. The mechanism consists of an arcuate
member made of piezoelectric material held in position at one end
of a casing and a weight movably supported against the inner
surface of the arcuate rnember by a spring. Two electrical
terminals are connected at opposite ends of the piezoelectric
~7~3
material. In the event of rapid deceleration, the inertia of the
weight exerts pressure on the piezoelectric material thus
inducing a voltage response between two terminals proportional to
the pressure. The proportional voltage is used to control the
activation of the airbags in the event of a collision.
Each of the patents referred to above discloses a mechanisrn
for automatically enabling a contact switch in the event of a
collision. However, none of the patents describes a inertia
switch which may be manually operated at the discretion of the
vehicle operator. In the case of hazard lights for example, it
is desirable that in the event of rapid deceleration or
collision, the hazard lights would be autornatically enabled, but
that they would otherwise be subject to manual operation by the
vehicle operator. Moreover, it is desirable in such
circumstances as a collision that means be provided for ensuring
that the inertia switch will remain engaged until disabled by the
vehicle operator.
OBJECTS OF THE INVENTION
It is therefore an object of the present inventinn to
provide an automatic inertia switch which may be manually
activated.
~27~
,,
It is a further object of this invention to provide an
automatic inertia switch which will remain activated after a
collision until manually deactivated.
It is yet a further object of the invention to provide such
an aukomatic inertia switch which is simple in construction and
which may be fitted to the dashboard of a motor vehicle.
SUMMARY OF THE_INVENTION
The inertia switch of the present invention comprises an
elongated member slidably extending through the dashboard of a
vehicle such that the longitudinal axis of the member is
substantially parallel to the direction of travel of the vehicle.
One end of the member is provided with manipulating means and the
opposite end of the member is provided with rneans for completing
an electrical circuit when the member is slid to its forwardmost
extent. Means extend between the member and a fixed point on the
frame of the vehicle, said means being capable of assuming a
first stable state in which the member is urged rearwardly and a
second stable state in which the member is urged towards it
forwardmost extent, said means further being capable of effecting
a transition from the first state to the second state when the
vehicle is subjected to rapid deceleration and from the second
~ ;27~
state to the first state when the member is pulled rearward by
said manipulating means.
FIGURES
The invention may be more fully appreciated by reference to
the illustrations and description of a preferred embodiment of
the invention, in which:
Figure 1 is a side elevation of the invention wherein the
elongated member is in its rearward configuration.
Figure 2 is a side elevation of the invention wherein the
elongated member is in its forwardmost position.
Figure 3 is a sectional view taken along line 3-3 of Figure
~' 2.
DETAILED DESCRIPTION OF THE PRE~ERRED EMBODIMENT
Referring to Figure 1, the dashboard of a vehicle is
designated by the numeral 1. The forward direction of travel of
the vehicle is indicated by arrow 2 while the rearward direction
of travel is indicated by arrow 1~.
`` ~.2~
A backplate 5 is secured by bolts 7 and 9 to the back of the
dashboard 1.
A bushing 8, which may be of nylon or other suitable
material is mounted integrally with backplate 5. A cylindrical
elongated push rod 6 extends through the bushing 8 in a direction
parallel to the direction of travel of the vehic:Le. The push rod
6 is adapted to slide through the bushing 8 along the push rod's
longitudinal extent.
Manipulating means 10 are provided at the rearward end 12 of
the push rod 6 whereby the vehicle operator may slide the push
rod 6 forward or rearward as desired, as more fully discussed
below.
The forward end 1ll of the push rod 6 is provided with means
16 to complete an electrical circuit when the push rod 6 is slid
to its forwardmost extent, as illustrated in Figure 2. In the
preferred embodiment described herein, such means 16 consists of
an electrically conduct:ive contact plate 18.
An electrical switch 20 is fixed to the vehicle in
longitudinally spaced relation with respect to the push rod 6.
Electrical switch 20 includes electrical contact points 22 and
~7QS~3
24, which open to a circuit 26 adapted to operate safety lights,
air bags, or other devices in the vehicle. Such devices will be
activated when the push rod 6 is slid to its forwardmost extent
thereby bringing the plate 18 into contact with the electrical
contact points 22 and 24 to close the electrical circuit 26, as
best illustrated in Figure 2.
As best illustrated in Figure 3, the push rod 6 is journaled
laterally through its diameter as at 28. A shaft 30 is disposed
through the journal 28. Shaft 30 is of a length greater than the
diameter of the push rod 6 so as to accommodate a mass 32 which
is secured to the push rod 6 about the journaled portion 28
thereof.
Still referring to Figure 3, each end 36, 38 of the shaft 30
acts as a fulcrum and securement point for a pair of rigid
connecting arms 40, 42 (about left end 36 of shaft 30) and 44, 46
(about right end 38 of shaft 30). A lock pin 48 retains the
shaf`t 30 in the journa]. 28.
It can therefore be seen that the mass 32 is sandwiched
between the connecting arms L10, 42, and 4l1, 46 about the
journaled portion 28 of the push rod 6.
- ~27~5~3
-- 8 --
The pair of connecting arrns 40, 44 iS adapted to be pivoted
about the ends 36, 38 of the shaft 30 independently of the pair
of connecting arms 42, 46.
Connecting arms 40 and 44 curve towards each other to be
pivotally secured to one end 48 of a first metal spring 50 by
means of a shaft 52. Similarly, connecting arms 42 and 46 curve
towards each other to be pivotally secured to one end 54 of the
second spring 56 by means of a shaft 58.
In the preferred embodiment described herein, the metal
springs 50 and 56 are made of flat elongated strips of resilient
and flexible metal. As best illustrated in Figure 1, the other
ends 60 and 62 of the metal springs 50, 56 respectively are
secured to the backplate 5 by rivets 64, 66, 68, 70.
The operation of the invention is as follows. In normal
operation of the vehicle, the push rod 6 is urged rearward by the
connecting arms which form an angle 72 with the push rod 6 which
angle ol)ens towards the front of the vehicle. In this state, the
tension induced by the curvature of the metal springs 50 and 56
maintains an inward pressure on the connecting arms which tends
to reduce the angle 72 and thereby urges the push rod 6 rearward.
In this stable state, the contact plate 18 is not in contact with
~7~543
the electrical contact points 22 and 24 and the circuit 26
remains open.
When the vehicle undergoes rapid deceleration, as in the
event of a collision, the momentum of the mass 32 will urge the
push rod 6 forward thus forcing the connecting arms to overcome
the tension in metal springs 50 and 56 and to pivot about the
shaft 30 to a new stable position wherein the push rod is slid to
its forwardmost extent as illustrated in Figure 2. The mass 32
must be chosen so that its momentum will overcome the metal
springs 50, 56 in such circumstances.
In this new stable state, the plate 18 is in contact with
electrical contact points 22, 24 thereby closing circuit 26 and
activating the safety and other devices which are connected to
the circuit 26. As best illustrated in Figure 2, the connecting
arms will form an angle 74 which opens towards the rear and the
downward tension from the metal springs will prevent the push rod
6 from spontaneously disengaging the plate 18 from the electrical
contact points 22, 24.
If the vehicle operator wishes thereafter to disengage the
safety or other devices, or to reset the inertia switch, the
~7~3
-- 10 _
operator may use the manipulating means 10 to urge the push rod 6
to the first stable position illustrated in Figure 1.
It will be appreciated by those skilled in the art that
variations of the preferred embodiment described herein may be
practiced without departing from the essence of the invention.
For example, the means for holding the push rod 6 in its
rearwardmost or forwardmost extents, which in the preferred
embodiment consists of the combination of pivoting connecting
arms and metal springs, may instead conslst any suitable means
attached about the push rod which are capable of effecting a
transition between a first stable state and a second stable
state.
Similarly, the means for completing the electrical circuit
26, which in the preferred embodiment consists of a contact plate
18, may instead consist of any suitable arrangement of components
known to those skilled in the art.
