U.S. patent number 3,801,767 [Application Number 05/313,652] was granted by the patent office on 1974-04-02 for pull-apart safety switch with magnetic means for machines.
Invention is credited to Robert G. Marks.
United States Patent |
3,801,767 |
Marks |
April 2, 1974 |
PULL-APART SAFETY SWITCH WITH MAGNETIC MEANS FOR MACHINES
Abstract
Several embodiments of pull-apart safety switches are disclosed
that are for use in connection with machines from which the
operator may be thrown or which he may leave with the machine
remaining in motion. Each switch includes a mount to be secured to
the machine and a cover so attached to the mount that it may be
pulled therefrom. The mount has leads to be included in the machine
circuit that is to be controlled. The cover is provided with a
flexible member attachable to the operator and of sufficient length
to enable him to make normal movements without pulling the cover
from the mount. Each switch also has a conductor and means
releasably holding it in a first relationship with the contacts
when the cover is attached and a second relationship therewith when
the cover is pulled free. In one of the two relationships, the
control system is operative to maintain the machine in operation.
Except when the control circuit is an ignition system having a
magneto, said one relationship is the first relationship and in
that case, said one relationship is the second relationship. In
most embodiments, the cover is magnetically held in place and in
second relationship circuit control, the conductor is within the
mount and is held from moving into its circuit-closing position
until the cover is pulled free, the conductor then being
operatively positioned magnetically, resiliently, or by both such
means.
Inventors: |
Marks; Robert G. (Walpole,
MA) |
Family
ID: |
23216563 |
Appl.
No.: |
05/313,652 |
Filed: |
December 11, 1972 |
Current U.S.
Class: |
200/543; 180/272;
335/205; 200/DIG.2; 200/334 |
Current CPC
Class: |
H01H
36/00 (20130101); H01H 35/00 (20130101); H01H
2036/0086 (20130101); Y10S 200/02 (20130101) |
Current International
Class: |
H01H
36/00 (20060101); H01H 35/00 (20060101); H01h
017/16 (); H01h 003/14 (); H01h 036/00 () |
Field of
Search: |
;200/161,DIG.2,61.45M,61.58B,153F ;335/205,206,207 ;180/82C |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
1,240,155 |
|
Mar 1967 |
|
DT |
|
1,438,461 |
|
Apr 1966 |
|
FR |
|
1,504,036 |
|
Oct 1967 |
|
FR |
|
Primary Examiner: Hohauser; Herman
Assistant Examiner: Vanderhye; Robert A.
Claims
I claim:
1. A pull-apart safety switch for the control circuit of a machine
and operable to prevent its operation if its operator is not at a
predetermined station, said switch comprising a mount attachable to
the machine and including first and second contacts, each a
permanent magnet, to which leads of the control circuit are to be
connected that enable the operation of the machine to be
controlled, a cover attachable to the mount in a manner enabling it
to be pulled therefrom, a conductor on the inside of the cover and
secured thereto, means releasably holding said conductor in a first
relationship with said contacts when said cover is attached to said
mount and providing a second relationship with said contacts when
said cover is detached from the mount, in one of said
relationships, said conductor being seated against said contacts
and in the other of said relationships said conductor being
disengaged therefrom, and in one of said relationships said control
circuit being operative to maintain the machine in operation and in
the other of which its operation is prevented, and a flexible
conductor secured to said cover with its free end attachable to the
operator, said connector being of such length that normal movements
of the operator are permitted without pulling the cover from the
mount.
2. A pull-apart safety switch for the control circuit of a machine
and operable to prevent its operation if its operator is not at a
predetermined station, said switch comprisng a mount attachable to
the machine and including first and second permanent magnet
contacts to which leads of the control circuit are to be connected
that enable the operation of the machine to be controlled, a cover
attachable to the mount in a manner enabling it to be pulled
therefrom, said mount having a pocket underlying said contacts, a
conductor within said pocket, said pocket of a depth enabling said
conductor to have two positions therein defining first and second
relationships with said contacts, in one of said positions, the
conductor being bottomed in the pocket, means releasably holding
said conductor in a first relationship with said contacts when said
cover is attached to said mount and providing a second relationship
with said contacts when said cover is detached from the mount, in
one of said relationships, said conductor being seated against and
held by said contacts and in the other of said relationships said
conductor being disengaged therefrom, and in one of said
relationships said control circuit being operative to maintain the
machine in operation and in the other of which its operation is
prevented, and a flexible conductor secured to said cover with its
free end attachable to the operator, said connector being of such
length that normal movements of the operator are permitted without
pulling the cover from the mount.
3. The pull-apart safety switch of claim 2 in which the means
operable to hold the conductor in its bottomed position is a member
disposed and dimensioned to extend between the contacts and
connected to the conductor and the means operable to effect the
engagement of the conductor with said contact portions when the
cover is pulled from the mount is a resilient diaphragm of a
material that is a non-conductor of electricity connected to said
member and biasing it in a direction in which the conductor engages
said contact portions but held by the cover when attached to said
mount to prevent such engagement.
4. The pull-apart safety switch of claim 2 in which the means
operable to effect the engagement of the conductor with the contact
portions are magnetic.
5. A pull-apart safety switch for a device having an electrical
operating source and first and second control circuits, said switch
operable to connect said circuits in the alternative to said
source, said switch comprising a mount attachable to the device and
including first and second contacts one for each circuit and
connectable therein, a third contact between said first named
contacts, permanent magnets that are non-conductors of electricity,
one magnet between the third contact and each of said first named
contacts and having opposed forces magnetically connected thereto,
a cover attachable to the mount in a manner enabling it to be
pulled therefrom, a magnetically responsive conductor within said
cover and secured thereto and for engagement with said three
contacts when said cover is attached to said mount and a second
conductor connectable to said source and including a portion of a
magnetically responsive material and engageable with said third and
one of said other contacts but resilient and normally spaced
therefrom when the cover is attached to said mount, the first
conductor being of a mass so much greater than that of the second
conductor that said portion of the second member is not
magnetically attracted to said magnet until the cover is separated
from the mount, and a flexible connector secured to said cover with
its free end attachable to the operator, said connector being of
such length that normal movements of the operator are permitted
without pulling the cover from the mount.
6. The pull-apart safety switch of claim 5 in which the mounting
means for the second conductor is a resilient arm of a material
that is not magnetically responsive and yieldably holds the second
conductor spaced from said first and third contacts.
Description
BACKGROUND OF THE INVENTION
The invention is adapted for use wherever it is desired to prevent
the operation of a machine if its operator is not in a position in
which the machine can be controlled to meet certain standards such
as performance and safety. While the invention can be used in so
controlling a wide range of machines, it is herein discussed with
particular reference to vehicles, especially such vehicles as
motorcycles, motor boats, particularly those equipped with outboard
motors, and snowmobiles.
The invention is herein discussed primarily in connection with its
use in vehicles such as those specifically referred to and as
stopping their engines.
Even in vehicles where the throttles are self-closing, they may
become stuck for various reasons and remain open. This is
particularly true in the case of snowmobiles whose
throttle-operating cables often become frozen. If this happens when
the operator has been thrown from his snowmobile, the snowmobile
continues in motion at a speed depending, of course, on the
position in which the throttle is caught. Even when the speed of
the vehicle is moderate, the snowmobile may be destroyed or badly
damaged. There have been occasions where injuries and even deaths
were caused by runaway snowmobiles, for one example, at a race
track when a runaway snowmobile killed a spectator.
The problem has been recognized and one solution utilizes a switch
to short out the spark when a sensor detects excessive accelerator
cable tensions indicating that it has become frozen.
THE PRESENT INVENTION
In accordance with the invention, the problems of preventing the
continued operation of a machine when its operator is not in a
predetermined location is met by means of a pull-apart switch
having a fixed mount, usually secured to the machine and a cover
attached to the mount in a manner enabling it to be pulled
therefrom. The cover has a flexible member whose free end is to be
pulled if the operator moves or is moved from his position. At
least in the case of vehicles, the free end is attachable to the
operator and of such length that his normal movements do not result
in the cover being pulled free of the mount.
The mount is provided with two contacts connectable to the ends of
the lead that controls the operation of the machine, a motor
circuit or an ignition circuit. The switch also includes a
conductor and means releasably holding it in a first relationship
with the contacts when the cover is attached to the mount and
providing a second relationship with the contacts when the cover is
pulled free. In one relationship, the conductor is seated against
the contacts to interconnect the lead ends and in the other
relationship, the conductor is spaced from the contacts. In one of
the two named relationships the control lead is operative to
maintain the machine in operation, the first or normally closed
relationship if the machine is powered by an electric motor or an
engine whose ignition system includes a generator and the second or
normally open relationship if the ignition system of an engine
includes a magneto.
In one embodiment, the cover is held magnetically to the mount and
in another, it is held in place by spring clips.
Another objective of the invention is to provide that the conductor
is part of the cover and is magnetically held in its first
relationship and another objective is to enable the second
relationship of the conductor where the safety switches are of the
normally open type, to be effected by resilient means,
magnetically, or by combinations thereof, the conductor being
movably positioned within the mount.
Yet another objective of the invention is to provide a pull-apart
switch that has first, second, and third contacts. When the first
and third contacts are included in a control circuit, first
relationship circuit control is provided. When the first and second
leads are included in a control circuit, second relationship
circuit control is provided.
A further objective of the invention is to provide pull-apart
switches of the last named type in which there are three conducting
contacts in the mount each having an appropriate one of the leads
secured thereto and with the contacts separated by magnets which
are of the ceramic type and hence non-conductors. The third contact
has an arm within the mount engageable with the second contact but
spring-biased out of contact therewith. The cover includes a
conductor interconnecting all three contacts when it is secured to
the mount so that in first relationship control, the controlled
circuit is opened when the cover is pulled from the mount. In
second relationship circuit control, the magnetic field as applied
to the switch arm is insufficiently strong to overcome the spring
bias until the cover is pulled from the mount.
SHORT DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, several embodiments of safety
switches in accordance with the invention are shown and
FIG. 1 is a perspective view of a snowmobile to the instrument
panel of which the mount of a safety switch of the normally closed
type is secured and the flexible member of its cover attached to
the clothing of the operator;
FIG. 2 is a plan view of the safety switch with its cover
attached;
FIG. 3 is a section taken approximately along the indicated lines
3--3 of FIG. 2;
FIG. 4 is a section similar to FIG. 3 taken transversely of a
normally open safety switch in accordance with the invention;
FIG. 5 is a like view but with the cover pulled free of the mount
and the switch closed;
FIG. 6 is a section, similar to FIG. 4, of a normally open safety
switch in accordance with another embodiment of the invention;
FIG. 7 is a like view but with the cover pulled free and the switch
closed;
FIG. 8 is an elevational view of another normally closed switch in
accordance with the invention;
FIG. 9 is a section taken approximately along the indicated lines
9--9 of FIG. 8;
FIG. 10 is a view showing the inside surfaces of the cover and the
mount;
FIG. 11 is a section, taken lengthwise of another embodiment of the
invention that may function as either a normally open or a normally
closed switch depending on which of its leads are employed;
FIG. 12 is a like view but with the cover removed; and
FIG. 13 is a section taken approximately along the indicated lines
13--13 of FIG. 11.
THE PREFERRED EMBODIMENTS OF THE INVENTION
While pull-apart switches, as previously stated, are adapted for
use in a wide variety of machines, they are herein discussed with
particular reference to snowmobiles.
In FIG. 1, the panel of a snowmobile is indicated at 10. The
snowmobile, with the embodiments of the invention illustrated by
FIGS. 1 - 5, will be assumed to have its ignition system including
a generator. As such systems are well known, no details thereof are
shown.
The mount 11 of a pull-apart safety switch, generally indicated at
12 and shown in FIGS. 2 and 3, is secured to the panel 10 and it
includes a pair of contacts 13 protruding from a molded body 14 of
insulating matrial in which they are embedded with their leads 15
exposed to interconnect the ends of a lead of the ignition system
that will permit the operation of the snowmobile engine only when
that control lead is closed. The contacts 13 are permanent
magnets.
The safety switch 12 includes a molded cover 16 of insulating
material shaped and dimensioned to receive within and have a short
overlap with the end of the mount 11 in which the contacts 13 are
exposed, the cover 16 protecting the interior from dirt, snow, etc.
and covering the contacts when the snowmobile is operable.
The cover 16 has a conductor 17 embedded therein but exposed on its
inner surface and of such length that when the cover 16 is fitted
on the mount 11, the conductor 17 seats against both contacts 13
and is magnetically held thereby thus releasably but securely
attaching the cover 16 to the mount 11 and establishes a normally
closed switch.
The cover 16 has a tab 18, usually but not always a depending tab,
to which one end of a flexible member 19 is connected with its
other end attachable to the clothing of the operator 20 in any
desired manner, by means of a safety pin or clip (not shown) by way
of examples. The flexible member 19 is of sufficient length to
permit, when attached to the operator, his normal movements without
pulling the cover 16 from the mount 11 but, should he be thrown
from the snowmobile, the cover is pulled free thus opening the
control lead of the ignition system and thereby immedately stopping
the snowmobile's engine.
The pull-apart safety switch illustrated by FIGS. 8 - 10 is another
embodiment of a normally closed siwtch and as it is generally
similar in construction and use to the switch 12, it will not be
detailed and parts that correspond thereto are distinguished by the
suffix addition "A" to the appropriate reference numerals.
The contacts 13A are spring clips and the conductor 17A is a bar
held by supports 22 embedded in the cover 16A. The contacts 13A and
the conductor 17A are so positioned that when the cover 16A is in
place, the conductor 17A is releasably caught by the contacts 13A
establishing a normally closed switch, with the contacts covered,
that opens if the cover 16A is pulled free.
The embodiments of the invention illustrated by FIGS. 4 and 5 are
for use where the ignition system includes a magneto and a normally
open ground lead that enables the engine to be stopped by closing
that control lead.
The pull-apart safety switch of FIGS. 4 and 5 is to be incorporated
in such a lead and is, accordingly, of the normally open type but
as it is otherwise generally similar to the normally closed
pull-apart safety switches that have been previously described,
corresponding parts are not again detailed but are distinguished by
the suffix addition "B" to the appropriate reference numerals.
In this embdiment of the invention, the mount 11B of the safety
switch 12B has a channel 23 in its body 14B underlying the contacts
13B and dimensioned to loosely receive the conductor 17B and of
such depth that when the conductor is bottomed therein, it is
spaced from the contacts 13B which are permanent magnets.
The inside of the cover 16B is provided with a post 24 of a
material that is a non-conductor of electricity and shaped and
dimensioned to fit between the contacts 13B to engage and bottom
the conductor 17B when the cover is fitted on the mount. The cover
16B also has a pair of magnetically responsive holders 25 exposed
on its inner surface, each positioned to engage the appropriate one
of the permanent magnet contacts 13B thus to releasably hold the
cover 16B attached to the mount 11B.
To ensure the engagement of the conductor 17B with the contacts 13B
of the cover 16B pulled free, the channel 23 has a central pocket
26 for a spring 27 operable to force the conductor into engagement
with the contacts 13B when it is not held bottomed by the post
24.
As the embodiment of the invention illustrated by FIGS. 6 and 7 is
generally similar, its parts that correspond to previously
described embodiments are distinguished by the suffix addition "C"
to the appropriate reference numerals. In this embodiment of the
invention, a post 28 is attached to the center of the conductor 17C
and the cover 16C has a central projection 24C. A resilient
diaphragm 29 of the material that is a non-conductor of electricity
seals the space between the permanent magnet contacts 13C but
yields when engaged by the projection 24C to enable the conductor
17C to be bottomed to provide the normally open switch position
when the cover 16C is in position.
In the embodiment of the invention illustrated by FIGS. 11 - 13,
parts that correspond to those of previously described embodiments
are distinguished by the suffix addition "D" to the appropriate
reference numerals.
In this embodiment the mount 11D has three conductors serving as
contacts 30, 31, and 32 separated from each other by a pair of
magnets 33 and 34, each a non-conductor as it is of the ceramic
type having magnetized particles embedded therein. Such magnets
have their sides functioning as their poles. In practice the
contacts and magnets are cemented together. An insulating sheet 35
is also cemented to the contact 32 and the end of a brass conductor
36 is cemented to the sheet 35. Leads 37, 38, and 39 are attached,
respectively, to the contacts 30 and 32 and to the conductor 36
which includes a resilient arm 36D spaced from the inner ends of
the contacts 30, 31, and 32 and provided with a magnetically
responsive conductor 40 dimensioned to seat against the inner ends
of the contacts 30 and 31 but normally held therefrom by the
resiliency of the conductor arm 36D. It will be noted that the
outer and inner ends of the contacts 30, 31, and 32 extend slightly
beyond the corresponding ends of the magnets 33 and 34. In practice
the inner ends of the assembled contacts, magnets, the sheet 35 and
the conductor 36 are fitted into a shell 41 housing and providing
space for the movement of the switch arm 36D and its conductor 40
and the assembly is molded into the material from which the mount
11D is formed with the leads outside the shell.
The cover 16D has its conductor 17D dimensioned not only to be in
engagement with the outer ends of all three of the contacts 30, 31,
and 32 but also to provide a conductor mass that is substantially
larger than that of the conductor 40.
When the leads 37 and 38 are connected to be included in the
control circuit, first relationship control is provided since the
conductor 17D is in engagement with all three of the contacts 30,
31, and 32. When the leads 37 and 39 are connected to be included
in a control circuit, second relationship control is provided.
Because of the substantial difference between the mass of the
conductor 17D and that of the conductor 40, the conductor 40 is not
magnetically pulled into engagement with the contacts 30 and 32
while the cover 16D is attached to the mount 11D.
While the mounts of the safety switches may be otherwise attached,
they are shown as having wings apertured to permit them to be
secured to the panel 10 by screws and preferably they also may have
on their back surfaces a length of a tape (not shown) having both
surfaces adhesive coated and with the exposed adhesive coated face
protected by a removable paper sheet.
* * * * *