Pressure release thermostat

An engine coolant thermostat for an internal combustion engine is provided with pressure release blowout plugs in the event that a thermostat should fail. These plugs may be formed from a fibrous material and in one embodiment, a dye is released to color the engine's coolant so as to indicate that the thermostat has failed. Further embodiments envision the use of umbrella-like strainers threadably attachable to the top of the thermostat, and these strainers may be periodically inspected to determine the type of debris and residue present in the engine's coolant.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to engine coolant thermostats and more 
particularly pertains to an engine coolant thermostat which is provided 
with a safety release means in the event of thermostat failure. 
2. Description of the Prior Art 
The use of safety devices in engine cooling systems is known in the prior 
art. For example, U.S. Pat. No. 4,691,669, which issued to Otteman et al. 
on Sep. 8, 1987, discloses an engine overheat protection system which 
indicates and signals the loss of coolant liquid as the result of a 
pressure drop at higher temperatures. This particular type of protection 
device relies upon a sophisticated electronic circuit to determine coolant 
and system pressure loss and to then activate the associated alarm. 
A simpler type of safety protection device is to be found in U.S. Pat. No. 
4,942,849, which issued to V. Shelton on Jul. 24, 1990 and which is 
directed to a fail-safe coolant thermostat system for an internal 
combustion engine. The disclosed thermostat utilizes a secondary cooling 
fluid passage which operates as a bypass valve means whenever the 
thermostat begins to fail or when engine temperature or coolant pressure 
exceeds a prescribed maximum. While being functional for its intended 
purpose, this type of thermostat is complex and expensive to manufacture 
and apparently, it has achieved no commercial success. 
As such, there appears to exist a need for new and improved simple and 
economical safety devices which would detect and prevent engine damage due 
to thermostat failure. In this respect, the present invention 
substantially fulfills this need. 
SUMMARY OF THE INVENTION 
In view of the foregoing disadvantages inherent in the known types of 
engine coolant thermostats present in the prior art, the present invention 
provides an improved engine coolant thermostat construction wherein the 
same utilizes blowout plugs to release coolant pressure in the event of 
thermostat failure. As such, the general purpose of the present invention, 
which will be described subsequently in greater detail, is to provide a 
new and improved engine coolant thermostat which has all the advantages of 
the prior art engine coolant thermostats and none of the disadvantages. 
To attain this, the present invention essentially comprises an engine 
coolant thermostat for an internal combustion engine which is provided 
with pressure release blowout plugs in the event that a thermostat should 
fail. These plugs may be formed from a fibrous material and in one 
embodiment, a dye is released to color the engine's coolant so as to 
indicate that the thermostat has failed. Further embodiments envision the 
use of umbrella-like strainers threadably attachable to the top of the 
thermostat, and these strainers may be periodically inspected to determine 
the type of debris and residue present in the engine's coolant. 
There has thus been outlined, rather broadly, the more important features 
of the invention in order that the detailed description thereof that 
follows may be better understood, and in order that the present 
contribution to the art may be better appreciated. There are, of course, 
additional features of the invention that will be described hereinafter 
and which will form the subject matter of the claims appended hereto. 
In this respect, before explaining at least one embodiment of the invention 
in detail, it is to be understood that the invention is not limited in its 
application to the details of construction and to the arrangements of the 
components set forth in the following description or illustrated in the 
drawings. The invention is capable of other embodiments and of being 
practiced and carried out in various ways. Also, it is to be understood 
that the phraseology and terminology employed herein are for the purpose 
of description and should not be regarded as limiting. 
As such, those skilled in the art will appreciate that the conception, upon 
which this disclosure is based, may readily be utilized as a basis for the 
designing of other structures, methods and systems for carrying out the 
several purposes of the present invention. It is important, therefore, 
that the claims be regarded as including such equivalent constructions 
insofar as they do not depart from the spirit and scope of the present 
invention. 
Further, the purpose of the foregoing abstract is to enable the U.S. Patent 
and Trademark Office and the public generally, and especially the 
scientists, engineers and practitioners in the art who are not familiar 
with patent or legal terms or phraseology, to determine quickly from a 
cursory inspection the nature and essence of the technical disclosure of 
the application. The abstract is neither intended to define the invention 
of the application, which is measured by the claims, nor is it intended to 
be limiting as to the scope of the invention in any way. 
It is therefore an object of the present invention to provide a new and 
improved engine coolant thermostat which has all the advantages of the 
prior art engine coolant thermostats and none of the disadvantages. 
It is another object of the present invention to provide a new and improved 
engine coolant thermostat which may be easily and efficiently manufactured 
and marketed. 
It is a further object of the present invention to provide a new and 
improved engine coolant thermostat which is of a durable and reliable 
construction. 
An even further object of the present invention is to provide a new and 
improved engine coolant thermostat which is susceptible of a low cost of 
manufacture with regard to both materials and labor, and which accordingly 
is then susceptible of low prices of sale to the consuming public, thereby 
making such engine coolant thermostats economically available to the 
buying public. 
Still yet another object of the present invention is to provide a new and 
improved engine coolant thermostat which provides in the apparatuses and 
methods of the prior art some of the advantages thereof, while 
simultaneously overcoming some of the disadvantages normally associated 
therewith. 
Still another object of the present invention is to provide a new and 
improved engine coolant thermostat which utilizes blowout plugs to release 
engine coolant pressure in the event of thermostat failure. 
Yet another object of the present invention is to provide a new and 
improved engine coolant thermostat which releases a coloring dye into the 
engine coolant system in the event of thermostat failure. 
These together with other objects of the invention, along with the various 
features of novelty which characterize the invention, are pointed out with 
particularity in the claims annexed to and forming a part of this 
disclosure. For a better understanding of the invention, its operating 
advantages and the specific objects attained by its uses, reference should 
be had to the accompanying drawings and descriptive matter in which there 
is illustrated preferred embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference now to the drawings, a first embodiment of a new and 
improved pressure release thermostat embodying the principles and concepts 
of the present invention and generally designated by the reference numeral 
10 will be described. 
Initially however, reference is made to FIGS. 1 and 2 of the drawings 
wherein prior art safety devices associated with engine coolant systems 
are illustrated. Both of these devices have been priorly discussed, and 
these figures are provided for the purpose of more clearly illustrating 
the state of the prior art. FIG. 1 relates to U.S. Pat. No. 4,691,669, as 
above-discussed, and FIG. 2 relates to U.S. Pat. No. 4,942,849, as also 
above-discussed. These figures are illustrative of the complexity of the 
prior art and the apparent problems associated with attempting to 
economically manufacture such devices. The present invention substantially 
overcomes these problems. 
With respect to the first embodiment 10 of the invention as illustrated in 
FIGS. 3 and 4, it can be seen that a conventional thermostat 12 may be 
modified to have a plurality of through-extending, trapezoidally-shaped 
apertures 14 into which a plurality of fiber rupture disks 16 may be 
adhesively or frictionally fitted. 
In use, these fiber disks are designed to possess sufficient strength to 
prevent their rupture during normal vehicle engine operation. However, in 
the event that the thermostat 12 should stick in a closed position, the 
engine coolant would experience a substantial rise in heat and pressure 
whereby the fiber disk 16 would rupture to allow the engine coolant to 
again flow through the system. Where a plurality of these disks 16 are 
utilized in a thermostat 12, each disk could vary in rupture strength 
characteristics from the other disks whereby a serial rupturing of the 
disks would occur as engine pressure and temperature increases. This would 
prevent an immediate decrease in temperature as indicated on an engine 
compartment gauge, whereby engine coolant temperature would remain high 
enough to indicate a thermostat failure to the vehicle operator. As can be 
appreciated, if the engine coolant temperature and resultant pressure 
continues to rise, additional disks 16 would rupture to further lessen the 
likelihood of substantial engine damage while still providing the vehicle 
operator with some indication of thermostat failure. 
FIGS. 5 and 6 illustrate a modified embodiment of the invention wherein a 
plug 18 is formed with top and bottom fiber mats 20, 22 respectively, and 
sandwiched between the mats is a layer of solid coloring dye 24. The dye 
24 would be designed to dissolve in the event of an unacceptable engine 
coolant temperature, thereby facilitating the release and rupture of the 
associated disk 20, 22. In this situation, where a vehicle operator is not 
sure that an engine thermostat failure has occurred (perhaps due to only a 
slightly higher temperature indication on a temperature gauge), the 
operator can inspect the coolant to determine if a color change has 
occurred. If such a color change has occurred, an indication of 
unacceptable engine coolant temperature is provided, as well as thermostat 
failure. 
Under certain circumstances, it may be desirable to inspect the engine 
coolant to determine the type of large particles and other residue flowing 
therethrough. Normally, solid residue will gravitate to the bottom of the 
radiator once the engine has ceased running, and it becomes difficult to 
determine if large particles of residue are actually flowing through the 
coolant. FIGS. 7, 8 and 9 illustrate a use of an umbrella-like particle 
capturing screen in combination with the thermostat 12. In this regard, 
FIG. 7 shows an umbrella-like shaped filtering screen 26 which is 
positioned over a threaded rod 28 and retained in such position by a wing 
nut 30. A remaining free end of the rod 28 is provided with a coupling 32 
which is directly attachable by some conventional means to the top of a 
thermostat 12 as best illustrated in FIG. 9. In operation, the screen 26 
tends to capture large residue and other particles from the flowing stream 
of coolant as above explained. Where only large particles are desired to 
be captured, a perforated cup member 34 may be used to replace the 
cup-like screen member 26. Through the simple removal of a coolant hose 
36, an engine operator can peer into the thermostat housing 38 to 
determine the extent of debris collection in either a screen 26 or 
perforated cup 34. 
As to the manner of usage and operation of the present invention, the same 
should be apparent from the above description. Accordingly, no further 
discussion relating to the manner of usage and operation will be provided. 
With respect to the above description then, it is to be realized that the 
optimum dimensional relationships for the parts of the invention, to 
include variations in size, materials, shape, form, function and manner of 
operation, assembly and use, are deemed readily apparent and obvious to 
one skilled in the art, and all equivalent relationships to those 
illustrated in the drawings and described in the specification are 
intended to be encompassed by the present invention. 
Therefore, the foregoing is considered as illustrative only of the 
principles of the invention. Further, since numerous modifications and 
changes will readily occur to those skilled in the art, it is not desired 
to limit the invention to the exact construction and operation shown and 
described, and accordingly, all suitable modifications and equivalents may 
be resorted to, falling within the scope of the invention.