U.S. patent number 3,853,199 [Application Number 05/310,943] was granted by the patent office on 1974-12-10 for collision sensor for fender bumper operated vehicle safety device.
This patent grant is currently assigned to Nissan Motor Company, Limited. Invention is credited to Yoshikazu Hayakawa, Kenzo Hirashima, Shunji Matsui.
United States Patent |
3,853,199 |
Hirashima , et al. |
December 10, 1974 |
COLLISION SENSOR FOR FENDER BUMPER OPERATED VEHICLE SAFETY
DEVICE
Abstract
An impact-responsive switch mounted on a shock-absorbing bumper
and having a housing for a bore. An elongate retractable member is
axially slidably mounted in the bore to retract to open or close
two contacts provided therein when subjected to a collision impact.
The elongate retractable member has attached thereto a permanent
magnet which, in the retracted position, applies an attractive or
repulsive force tending to close or open the two contacts which are
hermetically sealed within an evacuated glass tube to prevent
degeneration of the contacts. The impact-responsive switch is so
positioned on the bumper that the elongate member is subjected to
the collision impact upon compression of a resilient member which
is interposed between a back plate of a buffer bar and an end plate
of a piston rod forming a part of the bumper mechanism.
Inventors: |
Hirashima; Kenzo (Yokohama,
JA), Matsui; Shunji (Yokohama, JA),
Hayakawa; Yoshikazu (Yokosuka, JA) |
Assignee: |
Nissan Motor Company, Limited
(Yokohama City, JA)
|
Family
ID: |
26390176 |
Appl.
No.: |
05/310,943 |
Filed: |
November 30, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Nov 30, 1971 [JA] |
|
|
46-111870 |
Apr 28, 1972 [JA] |
|
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47-49731 |
|
Current U.S.
Class: |
180/274;
200/61.44; 200/61.51; 293/4; 200/61.08; 200/61.45R |
Current CPC
Class: |
H01H
35/146 (20130101); H01H 36/0006 (20130101); H01H
35/14 (20130101); H01H 3/24 (20130101); B60R
21/013 (20130101) |
Current International
Class: |
B60R
21/01 (20060101); H01H 36/00 (20060101); H01H
35/14 (20060101); H01H 3/00 (20060101); H01H
3/24 (20060101); B60r 021/00 (); H01h 003/16 () |
Field of
Search: |
;200/61.45R,61.53,6,16A,61.08,159A,166C,166BA ;335/205,206
;180/91-97,103,104 ;280/15AB ;293/4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Scott; James R.
Claims
What is claimed is:
1. In a motor vehicle having a safety device actuable in response
to a collision signal, at least one shock absorbing bumper, which
bumper includes an impact receiving member extending crosswise
horizontally of the vehicle, a cylinder disposed longitudinally of
the vehicle and secured to the vehicle's body, a piston axially
slidable in a bore of the cylinder, a piston rod extending
externally from the piston and having one end secured to the impact
receiving member, the piston rod being adapted to be withdrawn into
the cylinder when said impact receiving member deforms upon
collision against a solid obstacle, and a resilient member disposed
between the impact receiving member and the piston rod to partially
absorb an impact resulting from a collision,
a collision signal producing apparatus comprising, in
combination,
a normally closed, vehicle deformation responsive switch forming
part of a first electric circuit, said deformation responsive
switch including
an insulated housing mounted adjacent said resilient member and
disposed on said one end of the piston rod, the housing defining a
cavity formed therein,
means defining aligned niches in said one end of said piston rod
and said resilient member and lying adjacent said insulated
housing,
an elongate actuating member axially slidably mounted in the cavity
and extending externally of said housing, said elongated actuating
member being arranged to normally extend through said niche in said
one end of said piston rod into said niche formed in said resilient
member but to be withdrawn into said housing upon compression of
the resilient member resulting from the collision,
a fixed contact disposed in said cavity, and
a movable contact which is associated with said elongate actuating
member, disposed in said cavity and normally held in contact with
the fixed contact, the movable contact being movable to disengage
from the fixed contact in response to the withdrawal movement of
said elongate actuating member to open said first electric
circuit;
and a normally open, inertia responsive switch forming part of a
second electric circuit connected with the safety device for
producing the collision signal upon closure thereof, said inertia
responsive switch including,
an insulated housing mounted on the vehicle body adjacent to said
impact receiving member, the housing defining a cavity therein,
an inertia-responsive magnetic weight located in said cavity for
movement in a longitudinal direction of the vehicle body in
response to the inertia applied to the body during the
collision,
a movable contact disposed on said inertia weight,
a fixed contact disposed in said housing adjacent to the movable
contact, the fixed contact being positioned in a path of the
inertia responsive movement of said inertia weight,
means applying a force to usually hold said movable contact apart
from said fixed contact, the force being overcome by the inertia
force at a predetermined degree, and
electromagnetic means mounted in the cavity of said inertia
responsive switch housing and situated adjacent to the inertia
weight on the side opposite to the position of said fixed contact
to exert, upon energization thereof, an attractive force upon said
inertia weight to hold the movable contact apart from said fixed
contact, said electromagnetic means being connected with the first
electric circuit and adapted to be deenergized upon opening of said
first electric circuit;
whereby said movable contact of the inertia weight is allowed to
engage with the fixed contact at a predetermined degree of
collision which is enough to open said vehicle deformation
responsive switch, only by overcoming the force of said force
applying means to close said second electric circuit.
2. An apparatus according to claim 1, in which said movable contact
of the deformation responsive switch is disposed on the inner end
of said elongate actuating member.
3. An apparatus according to claim 2, further comprising means to
keep said elongate actuating member at its extended position.
4. An apparatus according to claim 3, in which said means to keep
said elongate actuating member at its extended position is a spiral
spring disposed between a wall of said cavity and said elongate
actuating member and preloaded to urge the actuating member toward
the extended position.
5. An apparatus according to claim 3, in which said means to keep
said elongate actuating member at its extended position is plate
spring having one end fixed to a wall of said cavity and preloaded
to urge the actuating member toward the extended position.
6. An apparatus according to claim 3, in which said means to keep
said elongate actuating member at its extended position is a
permanent magnet disposed on said housing to exert an attractive
force upon said movable contact on said actuating member to urge it
toward the extended position.
7. An apparatus according to claim 2, in which said fixed contact
of the deformation responsive switch is a tubular member of glass
coated thereon with an electrically conductive material and
disposed in contact with said movable contact, said tubular member
being adapted to be broken by said actuating member when said
actuating member is withdrawn thereby cutting off the electric
connection of said movable contact with said fixed contact.
8. An apparatus according to claim 1, in which said deformation
responsive switch further comprises a permanent magnet provided on
said elongate actuating member.
9. An apparatus according to claim 8, in which said movable contact
and said fixed contact of the deformation responsive switch form a
reed enclosed in a fluid-tight tube disposed adjacent to said
permanent magnet.
10. An apparatus according to claim 1, in which said cavity of said
housing of said deformation responsive switch is divided into a
first compartment and a second compartment by a partition member,
and accommodates therein a piston secured to the inner end of said
elongate actuating member, said piston being axially slidable in
the first compartment, and a bellows member provided within the
second compartment and communicating with the first compartment
through an opening formed in the partition member, and in which
said movable contact is disposed on the bellows member for movement
therewith and said fixed contact is provided in the second
compartment normally in contact with said fixed contact by a
tension spring, whereby upon compression of said bellows member,
said movable contact is removed from said fixed contact.
11. An apparatus according to claim 1, in which said inertia weight
of the inertia responsive switch is of a pendent type hanging from
the top wall of the housing by a flexible wire.
12. An apparatus according to claim 11, in which said force
applying means is a permanent magnet disposed adjacent to said
inertia weight on the side opposite to the position of said fixed
contact.
13. An apparatus according to claim 1, in which said force applying
means is a spring within said cavity extending in the longitudinal
direction of the vehicle and having one end anchored to the movable
contact on said inertia weight to urge it toward the
electromagnetic means.
14. An apparatus according to claim 13, in which said inertia
weight is a spherical member held in position by said spring.
15. A collision sensor for sensing a collision condition of a motor
vehicle to actuate a safety device mounted thereon, said collision
sensor being mounted on a shock-absorbing bumper which includes an
impact receiving member extending crosswise horizontally of the
vehicle, a cylinder extending longitudinally of the vehicle and
secured to the vehicle's body, a piston axially slidable in the
cylinder, a piston rod extending externally from the piston and
connected with the impact receiving member, and a resilient member
provided on the impact receiving member to partially absorb an
impact resulting from a collision, said collision sensor
comprising: a housing having a bore formed therein; an elongate
actuating member axially and slidably mounted in the bore and
extending externally of said housing, said elongate actuating
member being arranged to normally extend into a niche formed in the
resilient member but to be retracted into said housing upon
compression of the resilient member resulting from a collision;
biasing means for normally biasing said elongate actuating member
to its extended position; switch means provided in said housing for
actuating the safety device when said elongate actuating member is
forcibly moved to its retracted position, said housing having a
chamber divided into first and second compartments by a partition
member; and said elongate actuating member has a piston secured to
the inner end thereof, the piston being axially slidable in the
first axial compartment; and a bellows member is provided within
the second compartment and communicates with the first compartment
through an opening formed in the partition member; and said switch
means comprises a movable contact secured to the bellows member for
movement therewith, and a fixed contact provided in the second
compartment; and said biasing means comprises a spring provided
between the partition member and the movable contact to normally
keep the bellows member in a contracted condition, the movable
contact being kept in contact with the fixed contact when the
bellows member is contracted.
Description
This invention relates generally to motor vehicle safety devices
and more particularly to an improved switch mechanism of the
impact-responsive type to be mounted on a shock-absorbing bumper of
a motor vehicle.
Heretofore, many safety devices and collision sensors have been
developed for use on motor vehicles. Such collision sensor usually
comprises a switch mechanism which is adapted to be closed or
opened upon sensing a collision condition. It has been found in the
art that in order to successfully protect occupants from injuries
the switch is required to be closed or opened within one or two
milliseconds after a collision begins. Another requirement to be
satisfied by the switch mechanism of this kind is that it cannot be
readily actuated by anything else than a collision.
It is an object of the present invention to provide an improved
switch mechanism for a motor vehicle safety device that meets the
above-stated requirements for successfully protecting occupants
from injuries at the time of a collision.
Another object of the present invention is to provide an improved
switch mechanism which is adapted for use on a shock-absorbing
bumper of a motor vehicle to sense an impact upon the bumper
resulting from a collision of the vehicle.
It is a further object of the present invention to provide an
improved switch mechanism which is adapted for use with an inertia
switch of a known type to insure a reliable detection of a
collision of the vehicle.
It is still another object of the present invention to provide an
improved switch mechanism which is simple in construction,
inexpensive to manufacture and durable in use.
These and other objects will be readily apparent from the following
description of the invention taken in conjunction with accompanying
drawings, in which:
FIG. 1 is a side elevation, partly in section, of a shock-absorbing
bumper of a motor vehicle on which a switch mechanism according to
the invention is mounted;
FIG. 2 is an enlarged sectional view of the connection between a
buffer bar and a piston rod of the bumper mechanism, the switch
mechanism of the invention being shown as mounted on an end plate
of the piston rod;
FIG. 3 is a perspective view, with a schematic diagram of the
associated electrical circuit, of a shock-absorbing bumper
according to the invention;
FIG. 4 is a longitudinal sectional view of a typical switch
mechanism according to the invention;
FIG. 5 is a view showing the manner in which the switch mechanism
of the invention is mounted on the buffer bar of the bumper
mechanism;
FIG. 6 is a view of a modification of the switch mechanism of FIG.
4;
FIG. 7 is an illustration of a further embodiment of the switch
mechanism according to the invention;
FIG. 8 is a view of a typical hermetically sealed switch employed
in the device of FIG. 7;
FIG. 9 is a view of the switch mechanism of the invention having a
cover mounted thereon;
FIG. 10 is a view of a further embodiment of the switch mechanism
according to the invention which is of the pneumatically actuated
type;
FIGS. 11 and 12 are views of further modifications of the switch
mechanism of FIG. 4;
FIGS. 13 and 14 are views of typical examples of a tubular contact
member employed in the mechanism of FIG. 12;
FIGS. 15 and 16 are views of typical arrangements of an inertia
switch employed in combination with the switch mechanism of the
invention.
A simplified schematic diagram illustrating a preferred overall
arrangement of a shock-absorbing bumper to which the sensor or
switch mechanism of the invention is applied is shown in FIG. 1.
The bumper comprises an impact member, such as a buffer bar 10
extending crosswise and horizontally of the vehicle in front of the
front wheels or in the back of the rear wheels. The buffer bar 10
is of profiled steel type having a web portion 10a and upper and
lower inwardly directed flanges 10b. Affixed on the outer surface
of the web portion 10a is an elongate plate-like member 13 of
urethan foam or other suitable material that serves to lessen
impacts upon pedestrians which could otherwise cause critical
physical damages to them at the time of a collision. A back plate
or impact receiving member 15 is provided which extends between the
upper and lower flanges 10b of the buffer plate 10, the upper and
lower ends of the back plate 15 being secured to the inner surfaces
of the upper and lower flanges 10b, respectively, by welding or
other suitable method. The back plate 15 has one or more openings
17 formed therein (see FIG. 2) for securing thereto a piston rod 25
which forms part of a shock absorbing mounting 21.
The shock absorbing mounting 21 is preferably of the hydraulic
cushion type and comprises a cylinder 23, a piston (not shown)
axially movable within the cylinder 23, and the piston rod 25
extending from the piston toward the buffer bar 10. The cylinder 23
is secured on a longitudinally disposed frame portion or a side bar
27 of a vehicle chassis by means of bracket members 29.
As is best seen in FIG. 2, the piston rod 25 has mounted thereon or
integrally formed therewith an end plate 31 which is secured to the
back plate 15 by a bolt and nut assembly 33 with a resilient plate
member 35 interposed therebetween. The resilient member 35 is made
of foam rubber or any other suitable material that is sufficiently
resilient to absorb shearing stresses as well as compression
stresses. The opening 17 in the back plate 15, and its
corresponding openings 37 and 39 formed in the end plate 31 and the
resilient member 35, respectively, are so arranged as to have same
diameters which are somewhat larger than the outer diameter of a
bolt 33a so as to provide slight lateral movement or play of the
back plate 15 relative to the end plate 31.
The sensor or switch mechanism according to the invention is
generally designated by 50 and is mounted on the end plate 31 of
the piston rod 25 to sense an impact upon the buffer bar 10 at the
time of a collision. A typical example of the switch mechanism is
shown in FIG. 4, which comprises a casing or housing 52 having a
chamber 54 formed therein and an axial bore 56 extending from the
chamber 54. An elongate retractable member 58 is mounted in the
axial bore 56 slidably movable therein. The elongate member 58 has
secured at its inner end a plate 60 of electrically conductive
material for normally providing an electric path between two
contacts 62 and 63 provided in the chamber 54 on both sides of the
axial bore 56. The chamber 54 is also provided with a spring seat
65 for receiving a coil or helical spring 67 which acts to apply a
force on the end plate 60 to urge the elongate retractable member
58 to its fully extended position shown in FIG. 4. Connections to
the contacts 62 and 63 are made by wires 72 and 73, respectively,
which are connected to a vehicle safety device (not shown).
As seen in FIG. 2, the resilient member 35 and the end plate 31 of
the piston rod 25 have formed therein aligned openings 75 and 76,
respectively, which are of identical diameter somewhat larger than
the outer diameter of the elongate retractable member 58. The
sensor or switch mechanism 50 is secured to the surface of the end
plate 31 opposite to the resilient member 35 by suitable means (not
shown), with the elongate retractable member 58 extending through
the aligned openings 75 and 76. It should be noted that the length
of the elongate member 58 is such that there is a gap left between
the tip of the elongate member 58 and the surface of the back plate
15 under normal conditions.
In the operation of the arrangement shown in FIGS. 1, 2, 3 and 4,
when the buffer bar 10 is subjected to a strong impact due to a
violent collision of the vehicle against another one or a
stationary structure in the path of advance, the buffer bar 10 is
deformed instantly inwardly, causing the resilient member 35 to be
compressed. Even if a collision other than a headon one is
encountered by the vehicle, the resilient member 35 is compressed
by the back plate 15 of the buffer bar 10, since the plate 15 is
connected with the end plate 31 permitting a slight lateral
movement relative to each other, as described above. When this
occurs, the elongate member 58 is urged into the housing 52 by the
back plate 15, so that the end plate 60 of the elongated member 58
is moved in a right-hand direction as viewed in FIG. 4 against the
action of the spring 67. This will disconnect the contacts 62 and
63 from each other, resulting in actuation of the vehicle safety
device.
FIG. 5 shows the manner in which the sensor or switch mechanism 50
of the invention is applied to the buffer bar 10 so as to be
actuated upon compression of the resilient plate-like member 13
affixed on the outer surface of the web portion 10a. As
illustrated, the web portion 10a is formed with an opening 80
through which the elongate member 58 of the sensor or switch
mechanism 50 extends into a niche 82 formed in the resilient
plate-like member 13 adjacent the opening 80.
FIG. 6 illustrates another preferred embodiment of the sensor or
switch mechanism according to the invention which is different from
that of FIG. 4 in that a leaf spring 85 is employed in place of the
coil or helical spring 67. The leaf spring 85 is preloaded so as to
normally urge the elongate member 58' to its fully extended
position through a protuberance 87 provided on the end plate 60'.
The leaf spring 85 is made of electrically conductive material and
is normally kept in contact with a fixed contact 89 provided in the
housing 52'. When the elongate member 58' is caused to retract into
the housing 52' due to an impact thereon resulting from a collision
of the vehicle, the leaf spring 85 is moved away from the fixed
contact 89 resulting in actuation of the vehicle safety device.
FIG. 7 illustrates a further embodiment of the switch mechanism
according to the invention which includes a permanent magnet 90 for
magnetically actuating a hermetically sealed switch 92. As
illustrated, the sensor or switch mechanism also includes a casing
or housing 94 having a chamber 96 formed therein and an axial bore
98 extending from the chamber 96. An elongate retractable member
100 is axially slidably mounted in the axial bore 98 and is
normally biased to its fully extended position by means of a spring
102. The permanent magnet 90 is mounted at the inner end of the
elongate member 100 and, when the elongate member 100 is moved to
its retracted position, the magnet 90 is placed in a position
immediately above the hermetically sealed switch 92, where it
actuates the switch 92. The switch 92 is disposed within the
chamber 96 longitudinally of the housing 94 to extend along the
spring 102.
The switch 92, as best seen in FIG. 8, comprises an elongate hollow
tube 106 of electrically insulating material such as glass,
containing inert gas. Alternatively, the hollow tube 106 may be
evacuated to prevent degeneration of contacts provided therein. A
contact 108 extends into the interior of the tube 106 from the left
exterior side thereof and is preferably made of non-magnetic
material such as aluminum or copper. Another contact 110 is made of
resilient and magnetic material and extends into the tube 106 from
the right exterior side thereof toward the contact 108. The contact
110 is preloaded so that the tip thereof is normally held in
contact with the lower surface of the contact 108. When the
permanent magnet 90 is moved from the position indicated by the
solid line 90a to that indicated by the broken line 90b in response
to a collision, the tip of the contact 110 is moved downwards away
from the contact 108 due to a repulsive force applied thereto by
the magnet 90.
FIG. 9 illustrates the sensor or switch mechanism according to the
invention which includes a cover 120 mounted on the housing 52 to
enclose the elongate retractable member 58. The cover 120 serves to
prevent the entrance of dirt, water or other foreign matter into
the axial bore 56 (not identified) which would otherwise cause
corrosion of contacts or lead to malfunction of the switch
mechanism.
FIG. 10 illustrates a further preferred embodiment of the sensor or
switch mechanism according to the invention which sensor is
generally of the pneumatically actuated type. A casing or housing
130 has formed therein a chamber 132 which is divided into two
axial compartments 132a and 132b by a partition member 134 provided
in the chamber 132. A piston 136 is axially slidably mounted within
the compartment 132a and has a piston rod 138 extending externally
therefrom through an opening formed in the housing 130. The
partition member 134 is formed in the center thereof with an
opening 140 which communicates with the interior of a bellows
member 142 provided within the compartment 132a on the partition
member 134. The bellows member 142 is secured to a plate member 144
through which the bellows member 142 is normally compressed to its
contracted condition by means of a spring 146 provided between the
partition member 134 and the plate member 144. The plate member 144
is of electrically conductive material and is normally engaging a
contact 148 leading to a terminal 150. A fixed contact 152 is
provided between the partition member 134 and the plate member 144
and is normally held in abutting engagement with the conductive
plate member 144. Another terminal 154 is provided leading to the
fixed contact 152. When a collision takes place, the piston rod 138
is urged into the housing 130 to move the piston 136 in a
right-hand direction as viewed in FIG. 10, thereby causing the
bellows member 142 to expand. Expansion of the bellows member 142
moves the plate member 144 away from the fixed contact 152 against
the action of the spring 146, so that an electric circuit between
the terminals 150 and 154 is opened.
FIG. 11 illustrates still another preferred embodiment of the
sensor or switch mechanism according to the invention which is
similar to that shown in FIG. 4 except that the elongate
retractable member 58 is normally held in its fully extended
position by means of a magnet 160 instead of the spring 67 (see
FIG. 4). The magnet 160 may be a permanent magnet or an
electromagnet which is capable of holding the elongate member 58 in
the position shown without being affected by rather light impacts
not resulting from a collision of the vehicle.
FIG. 12 illustrates a still further preferred embodiment of the
sensor or switch mechanism according to the invention which is also
similar to that shown in FIG. 4 except that the contacts 62 and 63
are replaced by a tubular contact member 165. As is best seen in
FIG. 13, the tubular contact member 165 comprises two elongate
portions 165a and 165b which are made of glass or other suitable
material having thereon a coating of electrically conductive
material. When a collision takes place, the portions 165a and 165b
shatter, interrupting an electric path between terminals connected
thereto. The contact member 165 may be formed of carbon, and
further, it may be formed in a circular fashion as seen in FIG.
14.
The switch mechanisms as shown and described above are employed
separately or in combination with other collision-sensitive switch
types in order to insure a reliable sensing of a collision
condition which could possibly cause critical physical injuries to
the vehicle occupants.
FIG. 15 illustrates a typical arrangement of the inertia switch 170
which is of the sensitivity-modulating type. The switch 170
includes a weight 174 of magnetic material which is suspended by a
conductive wire 176 leading to a terminal 178. The weight 174 is
normally held in abutting engagement with a permanent magnet 180
and an electromagnet 182 which is energized by a battery 184
through the switch mechanism 50 of the invention. Since, in normal
condition, the weight 174 is held in the position shown with two
forces exerted by the permanent magnet 180 and the electromagnet
182, it will be appreciated that even a rapid acceleration or
deceleration of the vehicle during normal driving cannot cause
movement of the weight 174 away from the magnets 180 and 182.
However, when a collision occurs, the switch mechanism 50 is
opened, reducing to zero the force exerted on the weight 174 by the
electromagnet 182, so that the weight 174 is moved into contact
with a fixed contact 186 with a decreased force of inertia applied
to the weight 174. It will be appreciated that with this
arrangement it is possible to keep at a relatively low value the
magnitude of deceleration above which the inertia switch 17 is
actuated at the time of a collision.
FIG. 16 illustrates another arrangement of the inertia switch 170'
which is adapted for use with the sensor or switch mechanism of the
invention. The inertia switch 170' comprises a tubular member or
housing 190 having an internal cylindrical bore 192 fo formed
therein within which a weight in the form of a sphere 194 is
disposed. The weight 194 is normally held against one end wall of
the cylidrical bore 192 by a contact member 196 which in turn is
urged in a left-hand direction as viewed in FIG. 16 by a spring 198
provided within the cylindrical bore 192. Extending inwardly from
the other end wall of the bore 192 toward the contact member 196 is
another contact member 200 which leads to a terminal 202. The
spring 198 is of electrically conductive material, connecting the
contact member 196 to a terminal 204. The inertia switch 170' also
includes an electromagnet 206 provided in the left end portion of
the tubular member 190 adjacent the spherical weight 194. The
electromagnet 206 is connected in series with the switch mechanism
50 of the present invention and a battery 208. As in the case of
the arrangement shown in FIG. 15, provision of the electromagnet
206 serves to reduce the magnitude of deceleration above which the
inertia switch 170' is actuated at the time of a collision.
Although the present invention has been described above in
connection with the numerous embodiments of either a closed-open or
open-closed type switch members it should be understood that the
invention is not restricted to either one of the two types. It
would be possible to readily modify the switch mechanism from a
closed-open to open-closed or from open-closed to closed-open type.
In this connection, it should be noted that the switch mechanism
which is opened when a collision takes place is characterized by a
quick response in that even a slight movement of the movable
contact causes itself to be disconnected from the fixed
contact.
Furthermore, it should be noted that with the employment of the
hermetically sealed switch 92 shown in FIG. 8, the switch mechanism
of the invention has an increased durability in use since the
internally mounted contacts 108 and 110 are prevented from exposure
to the air.
Still furthermore, it should be noted that since the piston rod 25
of the shock absorbing mounting 21 is connected with the back plate
15 of the buffer bar 10 in a manner to permit slight lateral
movement relative to each other, the sensor or switch mechanism of
the invention is responsive to a collision other than a head-on
collision as well.
* * * * *