U.S. patent number 3,760,781 [Application Number 05/128,323] was granted by the patent office on 1973-09-25 for engine safety system having safety assembly indentifiably operable for each combustion chamber.
Invention is credited to Glen R. Boldt.
United States Patent |
3,760,781 |
Boldt |
September 25, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
ENGINE SAFETY SYSTEM HAVING SAFETY ASSEMBLY INDENTIFIABLY OPERABLE
FOR EACH COMBUSTION CHAMBER
Abstract
The safety system is for internal combustion engines, especially
snowmobiles, having at least two combustion chambers; each
combustion chamber is equipped with a safety assembly operable
independently of the others. Each individual safety assembly
includes a temperature sensor which is so mounted as to sense an
unsafe operating temperature for the specific combustion chamber
with which it is arranged. Preferred mounting of the sensor is at
the exhaust port for the combustion chamber, or alternately in a
position for reading temperatures from the base brass or copper
gasket for the spark plug. In the preferred embodiment, the sensor
automatically actuates a responsive switch means when unsafe
operating temperatures are reached; and this serves to interrupt
temporarily the intermittent electrical actuation of the ignition
means or spark plug for the combustion chamber. The interruption
lasts for the time the chamber is at the unsafe temperature. When
the chamber returns to a safe temperature, the switch automatically
serves to reinstate the intermittent electrical actuation of the
spark means for it. Additionally, however, a separate
manually-operated switch permits negation of the effect of the
automatic interruption so as to reinstate spark ignition even when
the individual combustion chamber is at the unsafe temperature. In
an alternate embodiment, the temperature sensor actuates a
responsive warning when an unsafe operating temperature for the
chamber is reached. The warning may be such as to illuminate an
instrument panel light or cause an audible sound (such as a buzzer)
for the chamber. Thereafter, a manually-operated switch controlled
by an operator may be shifted to terminate or interrupt temporarily
the intermittent electrical actuation of the ignition means for the
specific over-heated chamber.
Inventors: |
Boldt; Glen R. (Baldwin,
WI) |
Family
ID: |
22434773 |
Appl.
No.: |
05/128,323 |
Filed: |
March 26, 1971 |
Current U.S.
Class: |
123/630;
123/198DC |
Current CPC
Class: |
F02P
11/02 (20130101); F02D 17/04 (20130101) |
Current International
Class: |
F02P
11/00 (20060101); F02P 11/02 (20060101); F02D
17/00 (20060101); F02D 17/04 (20060101); F02p
011/02 (); F02p 011/06 () |
Field of
Search: |
;123/198DC,148S,148A,198F,146.5D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Assistant Examiner: Toth; Dennis
Claims
That which is claimed is:
1. An internal combustion engine having at least two combustion
chambers, each said combustion chamber having associated therewith
an inlet for combustibles, ignition means intermittently
electrically actuated to ignite combustibles within said chamber,
an exhaust outlet for products of combustion from said chamber, and
a safety assembly, said safety assembly for each said combustion
chamber being operable independently of the safety assembly for
each and every other combustion chamber of said engine, and each
said safety assembly comprising:
a. A temperature sensor mounted to sense an unsafe operating
temperature for the specific combustion chamber with which said
sensor is associated,
b. Responsive switch means automatically actuated by said sensor
when said specific combustion chamber reaches said unsafe operating
temperature, whereby said intermittent electrical actuation of said
ignition means for said specific combustion chamber is interrupted
during the time said specific combustion chamber is at said unsafe
operating temperature, said responsive switch means being operable
without interrupting the intermittent electrical actuation of the
ignition means for all of the other combustion chambers of said
engine, and
c. manually operated switch means for negating the effect of said
responsive switch means and thereby reinstating said intermittent
electrical actuation of said ignition means for said specific
combustion chamber, said manually operable switch means for each
said combustion chamber safety assembly being identifiably distinct
from the manually operated switch means for every other said
combustion chamber safety assembly.
2. The engine of claim 1 wherein the mounting of said temperature
sensor is such as to sense the temperature at the exhaust outlet
for said specific combustion chamber.
3. The engine of claim 1 wherein the mounting of said temperature
sensor is such as to sense the temperature at the base of the
ignition means for said specific combustion chamber.
4. The engine of claim 1 wherein said safety assembly comprises a
visual indicator automatically actuated by said sensor when said
specific combustion chamber reaches said unsafe operating
temperature, said visual indicator of each said combustion chamber
safety assembly being identifiably distinct from the visual
indicator for every other said combustion chamber safety
assembly.
5. The engine of claim 1 wherein said safety assembly comprises an
audible indicator automatically actuated by said sensor when said
specific combustion chamber reaches said unsafe operating
temperature, said audible indicator of each said combustion chamber
safety assembly being identifiably distinct from the audible
indicator for every other said combustion chamber safety
assembly.
6. A mobile vehicle powered by an air-cooled internal combustion
engine satisfying the requirements of claim 1.
7. An internal combustion engine having at least two combustion
chambers, each said combustion chamber having associated therewith
an inlet for combustibles, ignition means intermittently
electrically actuated to ignite combustibles within said chamber,
an exhaust outlet for products of combustion from said chamber, and
a safety assembly, said safety assembly for each said combustion
chamber being operable independently of the safety assembly for
each and every other combustion chamber of said engine, and each
said safety assembly comprising:
a. A temperature sensor mounted to sense an unsafe operating
temperature for the specific combustion chamber with which said
sensor is associated,
b. Responsive warning means automatically actuated by said sensor
when said specific combustion chamber reaches said unsafe operating
temperature, said responsive warning means being operable without
interrupting the intermittent electrical actuation of said ignition
means for said specific combustion chamber, and
c. manually operated switch means for temporarily interrupting
intermittent electrical actuation of said ignition means for said
specific combustion chamber during the time said specific
combustion chamber is at said unsafe operating temperature, said
switch means being operable without interrupting the intermittent
electrical actuation of the ignition means for all of the other
combustion chambers of said engine.
8. The engine of claim 7 wherein the mounting of said temperature
sensor is such as to sense the temperature at the exhaust outlet
for said specific combustion chamber.
9. The engine of claim 7 wherein the mounting of said temperature
sensor is such as to sense the temperature at the base of the
ignition means for said specific combustion chamber.
10. The engine of claim 7 wherein said responsive warning means
comprises a visual indicator for alerting an operator.
11. The engine of claim 7 wherein said responsive warning means
comprises an audible indicator for alerting an operator.
12. A mobile vehicle powered by an air cooled internal combustion
engine satisfying the requirements of claim 7.
Description
This invention relates to a safety system for internal combustion
engines, and more particularly, to an internal combustion engine
having at least two combustion chambers, with each such chamber
equipped with a safety assembly operable independently of the
others. The invention is especially directed to mobile vehicles,
particularly snowmobiles, equipped with an instrument panel and
powered by an internal combustion engine protected by the safety
system hereof.
Although the invention is useful in connection with internal
combustion engines of a variety of types, it is especially useful
and important in connection with snowmobile vehicles. Such vehicles
are normally powered by air-cooled engines. They are widely used in
racing and other rigorous cross-country conditions. The type of use
to which they are put causes the individual combustion chambers of
cylinders of the air-cooled engines to rise and lower in
temperatures relatively rapidly and differentially; that is, one
cylinder of the air-cooled engine may rise much more rapidly in
temperature than another or other cylinders of it. Such a resulr is
not common under racing conditions and can be quite common under
other rigorous use conditions. Contributing factors may be a
difference in lubrication for the different cylinders, or a
difference in heat dissipation through the fins of the air-cooled
engine. In any event, a serious problem exists with respect to
blowing pistons in individual cylinders of snowmobile engines when
an individual cylinder reaches excessive temperatures; and it is to
a solution for that particular problem that this invention is
especially directed.
The invention provides alternative solutions in terms of details;
and in this respect the preferred embodiment of the invention is
that which permits the desired safety features without requiring
the operator to remove his eyes from the terrain ahead even for an
instant. Optionally, the invention includes instrument panel
warning indicia which the operator may check visually at moments
convenient and safe for him so to do.
The invention is applicable to mobile vehicles powered by internal
combustion engines having at least two and preferably more than two
combustion chambers. Ordinarily these combustion chambers are
cylindrical chambers with reciprocating pistons therein. Each such
chamber has associated with it an inlet for combustibles (fuel and
oxygen), an ignition means (such as a spark plug) intermittently
electrically actuated to ignite combustibles within the chamber, an
exhaust outlet for products of combustion from the chamber, and a
safety assembly according to this invention. Each such safety
assembly operates independently of the safety assembly for each and
every other combustion chamber of the engine.
Each safety assembly comprises a temperature sensor which is so
mounted as to sense an unsafe operating temperature for the
specific combustion chamber with which it is associated. Mounting
of the sensor is preferably at the exhaust port or conduit for the
combustion chamber, or alternately at the base of the spark plug
for it. Responsive means is actuated by the temperature sensor when
the specific combustion chamber reaches the unsafe operating
temperature. Such unsafe operating temperatures will vary amongst
the different types of engines, depending largely upon the specific
material of the cylinder walls (which usually is steel), the
material of pistons therein (ordinarily lighter weight alloys which
melt at temperatures lower than the cylinder walls) and the
arrangement and type of air fins for air cooling.
Each safety assembly for each combustion chamber or cylinder is
equipped with an interrupting means for temporarily interrupting
the intermittent electrical actuation of the ignition means for
that combustion chamber during the time that individual or specific
combustion chamber is at an unsafe operating temperature. The
interrupting means for any one combustion chamber of the total
engine is operable without terminating or interrupting the ignition
means for combustibles in other combustion chambers of the
engine.
In the preferred embodiment for snowmobiles, the interrupting means
is automatically actuated by a responsive switch means which
controls the interruption and is actuated automatically by the
sensor when the unsafe operating temperatures are reached. A
further feature of this preferred embodiment is that of separate
manually operated switch means for negating the effect of the
automatic interruption or terminating of the intermittent
electrical actuation of ignition means for the combustion chamber
which reaches unsafe operating temperatures. Thus, in a race or
emergency, this manually operated switch may be used to reinstate
the intermittent electrical actuation of the ignition means for the
specific combustion chamber at the excessive temperatures,
hopefully with the result that the dangerous condition will soon
pass or at least not result in immediate blowing of the piston in
the over-heated chamber.
In an alternate embodiment of the invention, the temperature sensor
automatically actuates a responsive warning means when the unsafe
operating temperatures is reached. The warning may illuminate an
instrument panel light for the specific over-heated combustion
chamber, or cause an audible sound such as a buzzer for that
chamber, or effect both such alerting means. Thereafter, manually
operated switch means (preferably on the instrument panel) may be
employed to terminate or interrupt temporarily the intermittent
electrical actuation of the ignition means for the over-heated
chamber without total loss of power. A total power loss might in
some instances prove more hazardous to life and limb than any
possible danger associated with blowing a piston.
Preferably both major embodiments of the invention include alerting
means such as visual or audible indicators. The color of the visual
indicator or warning light for each combustion chamber ideally is
distinctive and different from the others. Where audible indicators
are solely used, or used in conjunction with warning lights, the
audible indicator for each chamber ideally is distinctive either by
pitch or volume or intermittent performance or otherwise. Thus an
operator is given intelligence as to the specific chamber which is
in a problem condition.
The invention will further be described by reference to a drawing,
made a part hereof, wherein:
FIG. 1 is a schematic circuit diagram, including schematically
shown elements for an internal combustion engine, illustrating the
preferred embodiment of the invention;
FIG. 2 is a schematic circuit diagram, including schematically
shown engine elements, illustrating an alternate embodiment of the
invention;
FIG. 3 is a fragmentary circuit diagram to illustrate the circuit
for a still further alternate embodiment of the invention;
FIG. 4 is a schematically illustrated spark plug and associated
temperature sensor;
FIG. 5 is a schematic cross section through a cylinder wall and
exhaust port therefrom including a temperature sensor mounted for
pick up of the exhaust temperature condition;
FIG. 6 is a diagrammatic cross-sectional showing of an air-cooled
internal combustion engine (partially broken away), particularly
illustrating two combustion chambers and the inlets and outlets
associated therewith; and
FIG. 7 is a diagrammatic showing of a snowmobile vehicle (partially
broken away), powered by an air-cooled internal combustion
engine.
FIGS. 6 and 7 show well-known matters such as a snowmobile 38, an
instrument panel 39, two internal combustion chambers or cylinders
19 and 20 of an air-cooled internal combustion engine 40,
reciprocating pistons 41 and 42 in the combustion chambers, a valve
controlled inlet 43 and 44 for each chamber for entry of
combustibles therein, and a valve controlled exhaust outlet 45 and
46 for each chamber. Ignition means 17 and 18, plus a temperature
sensors 21 and 22, are included in the showing of FIG. 6 for each
chamber 19 and 20 to aid in keying the illustration of FIG. 6 to
the main showing of the invention in FIGS. 1 through 5, inclusive.
Many obvious known details of engines can be visualized
conveniently and readily without the aid of a drawing. FIGS. 1
through 5, inclusive, of the drawing are limited to basic elements
for teaching the invention, and the relationships of those
elements.
As a starting point in explaining the invention in light of FIGS.
1-5 of the drawing, a reference to conventional well understood
elements will first be made. In both FIGS. 1 and 2, a conventional
primary ignition circuit is illustrated by a battery 10, an
ignition coil 11, and a breaker or breaker point system 12. As is
well understood, a secondary circuit through conductor 13 from the
secondary winding of the coil 11 goes to a distributor 14 or
equivalent means for sequential selective distribution of an
electrical pulse (from the coil 11 or equivalent) through discreet
conductors 15 and 16 to individual ignition means such as spark
plugs 17 and 18 for cylinders 19 and 20 of an internal combustion
engine. Only two combustion chambers or cylinders are illustrated
in the drawing for the sake of simplicity. The arrangement of
elements described thus far, as well as the use of equivalent or
alternate means for sequential distribution of the electrical pulse
to the ignition means or spark plugs 17 and 18, is well known. The
important feature is that each spark plug is provided with a source
which intermittently and according to prearranged timing serves to
ignite combustibles in the cylinder with which it is
associated.
Each combustion chamber of the engine is equipped with a safety
assembly; and each safety assembly includes a temperature sensor 21
and 22. The sensor 21 or 22 is mounted to sense the operating
temperature for the specific combustion chamber 19 and 20,
respectively, of the internal combustion engine with which the
sensor is associated. Specifically, as illustrated in FIGS. 4 and
5, the sensor 21 or 22 is, as a practical matter, either mounted to
receive conducted temperature through a conductor 23 from a brass
or copper bushing or gasket 24 at the base of the spark plug 25 for
the individual combustion chamber (as in FIG. 4), or is mounted to
receive conducted heat directly from the exhaust port or conduit 26
for products of combustion leaving the specific combustion chamber
(the wall 27 of which is shown in FIG. 5) prior to the time those
products of combustion enter any optional exhaust manifold or other
conduit system for conveying them away. Optionally, the sensor
might be placed in a special recess in the wall of a combustion
chamber or in still other locations effective to permit temperature
sensing of individual combustion chambers. Further, the sensor may
itself be somewhat remote from the chamber, provided it is
effectively coupled with it for sensing its temperature. Where the
sensor is displaced from the immediate area of the combustion
chamber, but is coupled with it, as in the case of the spark plug
arrangement in FIG. 4, the sensor should be adjusted to respond at
relatively lower temperatures than a sensor mounted in the exhaust
port or conduit for the combustion chamber. Further, unsafe
temperatures taken by conduction from a brass gasket 24 for the
spark plug 25 may be as low as 400.degree. or 450.degree. F. or
possibly 500.degree. F., whereas unsafe temperature readings at the
exhaust port normally will be relatively much higher, such as
around 1,000.degree. F., or even 1,400.degree. F., or more.
A variety of specific known temperature sensors may be employed.
Popular types are made of a bimetallic strip or a coil which curves
or unwinds (respectively) as temperature rises. The end of the
strip or coil of bimetallic material either makes or breaks contact
with a conductor at the level of temperature predetermined to be in
the unsafe range for a specific type of internal combustion engine
or the pistons and cylinders thereof. Any suitable sensor capable
of either making or breaking an electrical connection at a
predetermined unsafe operating temperature may be employed,
although the specific features of circuitry for the safety assembly
must be adjusted consistent with either the making or breaking of
contact.
In the embodiment illustrated in FIG. 1, the sensors 21 and 22 are
equipped with responsive switch means of the normally open or
broken circuit type; and this switch (or connector points) close to
complete a circuit at the unsafe operating temperature. This
automatically occurs when the unsafe temperature is reached, and is
caused by the bimetallic sensor element disproportionately
expanding to place an end thereof in electrical contact with a
fixed electrical contact disk. Such sensors and switch combinations
are well known (see, for example, disclosure in U.S. Pat. No.
3,421,489).
Because manually operated switches 28 and 29 (suitably in a bank of
manually operated switches on an instrument panel) is in the
normally closed position as the engine is ordinarily operated, the
automatic closing of the responsive switch means associated with
sensors 21 and 22 in FIG. 1 (at unsafe operating temperatures for
the specific combustion chamber each is sensing) will short out or
ground the electrical pulses from distributor 14 to the respective
spark plug 17 or 18 for the chamber at unsafe temperatures. The
shorting or grounding of the pulse for one spark plug by the safety
assembly associated with it does not interfer with the electrical
pulse to the other spark plugs.
Desirably the manual switches 28 and 29 are in a bank of switches
on an instrument panel of the vehicle. Each switch in the bank is
desirably associated with a panel light such as 30 and 31,
respectively, so that an operator can by visual inspection
determine the specific switch 28 or 29 which can (where desired, as
in a race) be shifted to an open condition to resinstate the
operation of the combustion chamber which is at unsafe temperature.
By shifting that switch 28 or 29 to open it, the operator can thus
reinstate intermittent electrical actuation of the ignition means
17 or 18 for the chamber. Further, by flipping the switch 28 or 29
back to closed, he can periodically check to determine whether the
unsafe temperature persists.
Either in combination with lights 30 and 31, or in substitution for
such lights, special different audible warning sounds, each
characteristic for a predetermined manual switch 28 or 29, may be
employed.
In FIG. 3, an embodiment is illustrated where the sensor 32
includes a responsive switch means of the normally closed type,
opening when unsafe operating temperatures are reached and thereby,
because of the illustrated circuitry in FIG. 3, interrupting the
electrical ignition pulse from distributor 14 to spark plug 17. A
manually operated by-pass switch 33 is used for reinstating the
connection from distributor 14 to spark plug 17 should the operator
determine that the risk of a piston blow out is worth taking for a
short period of time.
In the embodiment illustrated in FIG. 2, the operator is warned of
a dangerous temperature condition if it arises for a specific
combustion chamber, but must take manual action in order to stop
continued combustion in the chamber which is at unsafe
temperatures. The sensors 21 and 22 in FIG. 2 include or comprise
normally open switches which close at the unsafe temperatures. Upon
closing, they automatically electrically actuate a warning means 34
or 35, which may comprise either or both a visual (light) or
audible (buzzer) means. Warning means 34 and 35 are suitably in a
bank of such means on an instrument panel; and with each or
adjacent to each should be a manually operated switch 36 and 37
corresponding to or applicable to the safety system for the
combustion chamber. Thus, if warning means 34 alerts the operator,
he may elect, depending on his judgment, to shift switch 36 from a
normally closed position (for conduction of electrical pulses from
distributor 14 to spark plug 17) to an open and grounded condition
and thereby interrupt temporarily the intermittent electrical
actuation of the ignition spark for cylinder 19. And this is
optionally possible at his discretion without losing all power;
that is, without interrupting the spark ignition for combustion
chamber 20 or any other combustion chambers of the engine.
As used herein, the reference to "blowing" pistons refers to
damaging or "burning" the pistons as a result of overheating.
Overheating causes pistons to expand so greatly that they "freeze"
or "lock-up" in the cylinder, becoming damaged themselves in the
process and many times also causing damage to the cylinder
walls.
If desired, visual warning means such as needle heat guages could
be employed for individual cylinders in practicing the teachings
hereof, preferably in addition to other visual warning means; and
still other variations from the preferred embodiments illustrated
may be employed.
* * * * *