Note: Descriptions are shown in the official language in which they were submitted.
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LATCHING SYSTEM FOR VEHICLE SAFETY DEVICES
Background of the Invention
The present invention relates generally to safety devices mounted on vehicles,
such as crossing-arms and stop signs mounted on school buses, and more
particularly to a
latching system for maintaining the safety devices securely in place when the
vehicle is
moving while permitting such safety devices to be readily deployed when
desired.
For safety reasons, it is common practice for many vehicles to be provided
with
safety devices that move between a retracted position along side of the
vehicle when not
needed, and an extended or deployed position extending outwardly from the
vehicle when
needed.
A familiar example is a school bus that may include safety devices in the form
of
stop signs that are mounted on the side of the school bus to move between a
retracted
position at the side of the school bus and a deployed position at which it
extends
outwardly at an angle of ninety degrees so as to be visible to motorist in
other vehicles
near the school bus to warn such motorist that children are entering or
exiting the school
bus. Similarly, crossing-arms are mounted on the front bumper of school buses
to move
between a retracted position along the length of the bumper and an extended
position
extending outwardly and perpendicularly from the bumper, and thereby creating
a barrier
that requires small children to walk around the extended crossing-arm so that
they will be
visible to the driver of the school bus. Typical examples of safety devices of
this type are
disclosed in greater detail in U. S. Patent Nos. 4,339,744 and 4,697,541.
These safety devices are usually mounted to the school bus by a pivotal
mounting
connecting one end of the safety device to the school bus in cantilever
fashion, and the
safety device is operated by an electric or vacuum operated motor to pivot the
safety
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device outwardly about the one pivoted end. By virtue of this cantilevered
mounting
arrangement, the extending length of the safety device is not securely held in
place, even
when the safety device is at its retracted position along side the bus. For
example, a
typical crossing-arm may have an extending length of about five feet, and its
only
connection to the school bus is at its pivotal connection at one of its ends.
Wind gusts can be severe enough, in some cases, to cause the safety device to
move away from its retracted position, and when the school bus is in operation
and
moving, the inherent bouncing and bumpy motion created by such movement,
combined
with the aforesaid generally insecure cantilever mounting of the safety
device, results in
significant vibration of the safety device about its pivotal mounting. Such
vibration, and
the lack of a secure attachment of the safety device to the vehicle, can (and
usually does)
result in excessive wear on the bearings and other parts of the operating
mechanism used
for deploying and retracting the safety device, which over time can cause the
safety
device to malfunction, or at least require excessive maintenance.
Additionally, when a school bus is stopped with the safety device in its
retracted
position (e. g. when the school bus is parked), the safety device,
particularly a crossing-
arm, provides a tempting opportunity for a child to attempt to manually pull
the safety
device away from the bus to its extended position, which not only creates a
dangerous
situation for the child, but also can cause damage to the safety device and/or
its operating
system.
Some efforts have been made to develop a mechanical latch to engage the safety
device and mechanically hold it in place, but these devices have not be
successful --
primarily because there is too much vibration of the safety device to be
successfully
restrained by a mechanical latch, and also because it was not practical to
develop a
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mechanical latch which could be readily mounted on the wide variety of school
bus
bumpers and mounts which carry the safety devices.
Accordingly, there exists a need for a latching system that can securely
maintain a
safety device in place when it is not being used, yet permit deployment of the
safety
device when necessary.
Summary of the Invention
The present invention provides a latching system for selectively maintaining
in
place a safety device, pivotally mounted on a surface of a vehicle, for
movement between
1.0 a retracted position adjacent such surface, and an extended position at
which it extends
outwardly from the vehicle. The latching system includes an electrically-
operated
latching device mountable on the vehicle and operable between a first
condition at which
it engages the safety device and maintains it securely in place adjacent the
vehicle, and a
second condition at which it releases the safety device to permit movement
thereof
between its retracted and extended positions. An electrical control circuit is
provided for
operating the latching device to maintain the latching device in its first
condition when
the vehicle is moving, and for operating the latching device to maintain the
latching
device in its second condition when said vehicle is stopped.
In the preferred embodiment of the present invention, the electrically-
operated
latching device is an electromagnet, and the safety device is either a
crossing-arm or a
stop-arm. If the safety device is a crossing-arm, the electromagnet is mounted
on the
bumper of a school bus, and the crossing-arm has a portion thereof, which is
composed of
magnetically attractive material and which is disposed to be adjacent the
electromagnet
when the crossing-arm is at its retracted position along the length of the
bumper. This
portion may either be a part of the crossing-arm itself, if it is made of
metal, or if the
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crossing-arm is made of plastic or other non-magnetic material, a piece of
magnetically
attractive material may be attached to the crossing-arm.
Also, in the preferred embodiment of the present invention, the safety device
is
operated between its retracted and extended positions by an electric motor,
and a control
switch is mounted in the door of the vehicle and is operated by the movement
of the door
which causes the electric motor to move the crossing-arm from its retracted
position to its
extended position when the door is open, and to move the crossing-arm from its
extended
position to its retracted position when the door is closed. This control
switch operates the
electrical control circuit to cause the electromagnet to be energized when the
door is
closed and to be de-energized when the door is open.
Brief Description of the Drawings
Fig. 1 is a general view of a school bus, illustrating an extended stop-arm
and an
extended crossing-arm which are operable with the present invention;
Fig. 2 is a perspective view, illustrating a crossing-arm being maintained in
place
by a latching system of the present invention;
Fig. 3 is a perspective view, similar to Fig. 2, illustrating the crossing-arm
after it
has been released by the latching system and is moving to or from its deployed
position;
Fig. 4 is a detail view, illustrating a plastic crossing-arm being maintained
in place
by a latching system of the present invention;
Fig. 5 is a detail view, illustrating a stop-arm being maintained in place by
the
latching system of the present invention; and
Fig. 6 is a schematic view, of the electrical control circuit forming part of
the
latching system of the present invention.
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Description of the Preferred Embodiments
Looking now in greater detail at the accompanying drawings, Fig. 1 shows a
typical school bus 10 having mounted there on at one side of the school bus 10
a stop-arm
12 that is operated by a conventional and well known electro-mechanical
operating unit
14 which, as will be described in greater detail below, causes the stop-arm 12
to be
moved between a retracted position extending along the side of the school bus
10, and a
deployed or extended position at which it extends outwardly at a ninety-degree
angle
from the school bus so that it is visible to motorists behind and in front of
the school bus
10. Similarly, a crossing-arm 16 is pivotally mounted to an operating unit 18
that may be
identical to the operating unit 14 to move the crossing-arm 16 between a
retracted
position along side the front bumper of the school bus 10 and a deployed or
extended
position as shown in Fig. 1 at which it extends outwardly at a ninety degree
angle from
the front bumper of the school bus 10 so as to provide a barrier that requires
school
children to walk around the crossing-arm 16 at a location that is visible to
the driver in the
school bus 10 as compared to walking directly in front of the school bus 10
along the
front bumper where small children may not be visible to the driver. As will be
seen in
Fig. 1, and as is well known in the art, the stop arm 12 and the crossing 16
are pivotally
mounted at one end thereof to there respective operating units 14, 18, and
they are
supported in cantilevered fashion by the pivotal mounting to the operating
units 14,18.
In accordance with the present invention, an electromagnet 20 is mounted on
the
front bumper of the school bus 10 as best seen in Figs. 2 and 3, and the
crossing-arm 16,
which is preferably in form of a "figure-8" design as disclosed in US Patent
No.
4,697,541, and if the crossing-arm 16 is not made of a magnetically attractive
material, a
small plate 22 of magnetically attractive material may be attached to the
crossing-arm 16
at a location that will position plate 22 at the electromagnet 20 when the
crossing-arm 16
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is at its retracted position as shown Fig. 2. If, on the other hand, the
crossing-arm 16 is
itself made of magnetically attractive material, such as steel, the plate 22
is unnecessary,
and the crossing-arm 16 itself is arranged to be positioned adjacent the
electromagnet 20
when the crossing-arm 16 is at its retracted position.
Figs. 4 and 4A show an alternate embodiment of the present invention in which
the crossing-arm 16' is made of a strip of relatively thin plastic material,
and the
magnetically attractive plate 22' is secured to the end of the crossing-arm
16' so as to be
adjacent the electromagnet 20 when the crossing-arm 16' is at its retracted
position.
As illustrated in Fig. 5, the electromagnet 20 may also be used to maintain a
stop-
arm 12 in place, and since most stop-arms 12 are made of steel or other
magnetically
attractive materials, the electromagnet 20 is positioned so that it will be
adjacent to the
stop-arm when it is in its normal retracted position along side the operating
unit 14. If the
stop-arm 12 is made of a non-magnetic material, then a plate similar to the
plate 22 can be
secured to the stop-arm 12 in the same manner as that described above in
connection with
the crossing-arm 16.
As is well known in the art, and as explained in greater detail for example in
US
Patent Nos. 4,339,744, 4,559,518, and 4,983,949, it is a common practice to
operate the
stop-arm 12 and the crossing-arm 16 using a door switch 24 which is
mechanically
opened and closed by the door of the school bus 10. Briefly summarized, in
such known
systems, when the school bus 10 stops to either let children enter or exit the
school bus
10, the driver will open the door of the school bus which closes the door
switch and
thereby connects the motor 30 (see Fig. 6) of the operating units 14 and 16 to
the battery
26 of the school bus 10, and these motors 30 then cause the stop-arm 12 and
crossing-arm
16 to be pivoted outwardly from their retracted positions to their extended
positions as
shown in Fig. 1. After the children have safely entered or exited the school
bus 10, the
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driver closes the door of the school bus 10 which opens the door switch 24,
and the
electrical control circuit 32 for the operating units 14, 18 operates the
motors 30 to return
the stop-arm 12 and crossing-arm 16 to their retracted position along side the
school bus
10. In accordance with one feature on the present invention, this existing and
known door
switch 24 is utilized to operate the electromagnet 20 of the present
invention.
More specifically, as schematically illustrated in Fig. 6, the door switch 24
is
arranged in circuit with the existing battery 26 of the school bus 10 through
the ignition
switch 28 for the school bus 10, and the door switch 24 controls the motors 30
for the
stop-arm 12 and the crossing-arm 16 in the conventional and known manner as
that
discussed above. The door switch 24 also controls the electromagnet 20. 'The
door
switch 24 is normally open when the door of the school bus 10 is closed, and
the control
circuit 32 for the electromagnet 20 operates to energizes the electromagnet 20
whenever
the door switch 24 is open, and to de-energize the electromagnet 20 whenever
the door
switch 24 is closed.
Accordingly, since the door of the school bus 10 will always be closed when
the
school bus 10 is moving, the electromagnet 20 will be energized, and the
adjacent stop-
arm 12 or crossing-arm 16 will be maintained in place and held against the
electromagnet
20, so as to reduce or eliminate the normal vibration of the cantilever-
mounted safety
device caused by the irregular movement of the school bus 10 as it moves along
uneven
road surfaces, particularly unpaved rural roads which are frequently
encountered by
school buses.
However, once the school bus 10 stops and the door of the school bus 10 is
opened, the door switch 24 will cause the control circuit 32 to de-energize
the
electromagnet 20, and the stop-arm 12 or crossing-arm 16 will then be released
by the
electromagnet 20 so that it ca be readily moved between its retracted and
extended
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positions by the motors 30 in the conventional manner described above. Thus,
the
electromagnet 20 does not interfere in any way with the normal operation of
the stop-arm
12 and the crossing-arm 16, yet it is operable to always maintain the stop-arm
12 and
crossing-arm 16 securely in place along side school bus 10 during movement of
the
school bus 10.
In the preferred embodiment of the present invention, the door switch 24,
which
already exists on most school buses, is effectively used to also control the
electromagnet
20. However, it will be understood that any conventional switch arrangement
could be
used in place of the door switch 24 to energize the electromagnet 20 when the
bus is
moving, and to de-energize the electromagnet 20 whenever it is necessary to
operate the
stop-arm 12 and/or crossing-arm 16. Also, in the preferred embodiment of the
present
invention, the electromagnet 20 is positioned so that it will be located near
the outer most
end of the cantilever-mounted crossing-arm 16 or stop-arm 12 to thereby
provide the
maximum stability when the electromagnet 20 is energized, but the
electromagnet 20
could be located at any position that will provide effective stabilization of
the stop-arm 12
and the crossing-arm 16. It is also within the scope of the present invention
to simply
reverse the magnetism of the elements 20 and 22, whereby 22 would be a
permanent
magnet, and 20 would be a demagnifier, such as a solenoid, which when
energized, would
cancel the magnetism of the permanent magnet and release the safety device. In
this type
of system, the element 20 would be de-energized when the door is closed and
the school
bus is moving, and energized when the school bus door is open.
It will therefore be readily understood by those persons skilled in the art
that the
present invention is susceptible of broad utility and application. Many
embodiments and
adaptations of the present invention other than those herein described, as
well as many
variations, modifications and equivalent arrangements, will be apparent from
or
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reasonably suggested by the present invention and the foregoing description
thereof,
without departing from the substance or scope of the present invention.
Accordingly,
while the present invention has been described herein in detail in relation to
its preferred
embodiment, it is to be understood that this disclosure is only illustrative
and exemplary
of the present invention and is made merely for purposes of providing a full
and enabling
disclosure of the invention. The foregoing disclosure is not intended or to be
construed to
limit the present invention or otherwise to exclude any such other
embodiments,
adaptations, variations, modifications and equivalent arrangements, the
present invention
being limited only by the claims appended hereto and the equivalents thereof.
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