A fail-safe thermostatically operated valve includes a temperature-responsive actuator for moving a valve element between a retracted position and an extended position. The valve includes a first cylindrical member and a second cylindrical member which are releasably connected to one another by a temperature-responsive release device which is responsive to a second predetermined temperature above the normal operating temperature of the valve. A spring arrangement provides return capability for the valve element and overtravel capability for the valve in the normal temperature operating range, and biasing force to move the valve element from the retracted to the extended position when the temperature-responsive release device operates. In one embodiment, the temperature-responsive release device includes a miniature wax-filled actuator in engagement with a mechanical linkage. In an alternate embodiment, the temperature-responsive release device comprises a heat fusible material.

BACKGROUND OF THE INVENTION 
Thermostatically operated valves are used in vehicle engines in which they 
move between an unactuated position and an actuated position to control 
the flow of a fluid such as water or oil through a cooler, for example, a 
radiator, in response to the temperature of the fluid. These valves have 
been known to fail, so that they remain in their unactuated positions. The 
failure of such valves in such a position has resulted in significant 
overheating of the water or oil and severe damage to the engine. 
In response to the problem of thermostatic valve failure, fail-safe devices 
have been designed which include safety provisions in case the valve fails 
to operate in its principal mode as intended. For example, U.S. Pat. No. 
3,045,918 to Woods discloses an actuator in which a valve element is 
biased to the closed position by a spring in tension. Furthermore, one 
embodiment of the actuator is disclosed in which a predetermined 
temperature above the range of normal operating temperatures of the valve 
causes the softening of material which anchors the spring to the valve 
element, thereby allowing the valve element to fall away from the valve 
seat. U.S. Pat. No. 3,498,537 to Wong discloses a fail-safe thermostatic 
valve which is mounted in a flow path by means of an annular connector 
member of fusible material which melts or softens at a temperature above 
the normal operating temperature, so that the pressure of the fluid moves 
the valve out of its mounting and permits the flow of fluid around the 
valve. U.S. Pat. No. 3,776,457 to Cardi discloses a thermostatic valve 
mounted in parallel with a heat softenable plug, so that if the valve 
fails to open, the plug will soften and open in response to a temperature 
above the temperature for which the thermostatic valve is designed, 
whereby a flow of the controlled fluid bypasses the valve. 
Although the foregoing prior devices disclose the concept of fail-safe 
arrangements, the Cardi device, for example, requires a thin-wall support 
structure in order to mount the plug in parallel with the valve. In 
addition, none of the devices mentioned includes a mechanism for 
positively clearing an opening through which the fluid can flow when the 
valve operates in the fail-safe mode. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide a reliable 
thermostatically operated valve which operates positively to control the 
flow of fluid through the valve in the event of failure of the valve. 
It is another object of the present invention to provide a fail-safe 
thermostatically operated valve which includes a spring arrangement for 
biasing the valve to the closed position in the event of failure of the 
valve and for providing overtravel accommodation for the valve during 
normal operation. 
In order to fulfill these and other objects, the thermostatic valve 
according to the present invention comprises a first cylindrical member 
disposed within a releasably secured to a second cylindrical member, and 
an actuator in the form of a temperature-responsive wax-filled element 
supported by the first cylindrical member. The actuator includes a piston 
and a guide member, the guide member supporting a snap ring on which is 
mounted a return spring concentric with the actuator. The return spring is 
connected through a spring locator to a cylindrical valve element having 
an open end and a closed end adapted to engage a valve seat when the 
temperature of the controlled fluid attains a first predetermined value. 
At this temperature, the fluid heats the wax in the actuator and causes 
the piston to extend. Additional heating of the wax causes additional 
relative movement between the piston and the guide member in the form of 
overtravel, which is accommodated by an overtravel spring mounted between 
an annular projection on the actuator and a top portion of the valve in 
order to bias the actuator toward the valve seat. The first cylindrical 
member is releasably secured to the second cylindrical member by a 
temperature-responsive release device which is responsive to a second 
predetermined temperature above the normal operating range of the valve to 
release the first member from the second member, thereby permitting the 
overtravel spring to bias the first cylindrical member and the cylindrical 
valve element which is supported thereby toward the valve seat so that the 
valve element engages the valve seat and prevents flow therethrough. 
In one embodiment, the temperature-responsive release device includes an 
auxiliary actuator in the form of a wax-filled element, responsive to the 
second predetermined temperature for producing a positive-movement. The 
auxiliary actuator engages a releasable mechanical linkage between the 
first cylindrical member and the second cylindrical member, whereby the 
auxiliary actuator responds to the second predetermined temperature to 
release the connection between the first and second cylindrical members. 
The release permits the overtravel spring to bias the first cylindrical 
member and the valve element carried thereby toward the valve seat so that 
the valve element engages the valve seat and prevents flow therethrough. 
In this embodiment of the invention, the thermostatically operated valve 
is reusable since, when it cools, the actuator can be returned to its 
unactuated position and the mechanical linkage can be returned to its 
initial position connecting the first and second cylindrical members and 
preventing relative movement therebetween. 
In an alternate embodiment according to the present invention, a heat 
fusible material can be used to connect the first and second cylindrical 
members and prevent relative movement therebetween. Thus, when the 
temperature of the controlled fluid reaches the second predetermined 
temperature which is above the normal operating range of the valve, the 
material fuses so that the first cylindrical member is biased by the 
overtravel spring toward the valve seat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As is illustrated in FIG. 1, the fail-safe thermostatically operated valve 
according to the present invention, which is generally designated by the 
reference numeral 10, is positioned in a cavity 12 in an engine block 14 
to control the flow of a fluid such as oil or water in response to the 
temperature of the fluid. A valve seat 16 is defined in the lower portion 
of the cavity 12 so that it may be engaged by the valve 10 to prevent flow 
through the valve seat. 
As can best be seen from FIG. 2, the valve 10 comprises a first, inner 
cylindrical member 18 and a second, outer cylindrical element 20 
concentric with the inner cylindrical element 18 and in contact with an 
outer surface thereof. The outer cylindrical member 20 includes at one end 
a radially extending shoulder 22 and an annular upstanding flange 24 
projecting from the shoulder 22. The outer cylindrical member 20 is 
connected to a supporting cap 26, which supports the valve 10 in the 
engine cavity 12 through a cup member 28 which is secured to the cap 26 
and turned-in under the shoulder 22 to support the outer cylindrical 
member 20. The cap 26 includes a plurality of apertures 30 for receiving 
cap screws or other suitable fastening devices to hold the cap 26 and the 
valve 10 in place in the cavity 12. 
The inner cylindrical member 18 includes an inwardly extending annular 
flange 32 for carrying a lower surface of an annular projection 36 on a 
wax-filled temperature-responsive actuator generally designated by the 
numeral 38. An opposite surface of the annular projection 36 is engaged by 
an overtravel spring 40 which is concentric with the actuator 38 and is 
under tension between the annular projection 36 and the cup 28 to bias the 
actuator 38 and the inner cylindrical member 18 toward the valve seat 16. 
The actuator 38 is a conventional device which includes, besides the 
annular projection 36, a filling of wax, which when heated melts and 
expands, forcing a piston 42 to an extended position. The piston 42 moves 
within a guide 44 which includes at its lower end a grove for receiving a 
snap ring 46 on which is mounted a coiled return spring 48. The return 
spring 48 extends upwardly from the snap ring 46 and engages the underside 
of a generally disc-shaped spring locator 50 which includes a plurality of 
circumferentially spaced, radially extending tabs 52. The tabs 52 extend 
through apertures 54 defined in the annular wall of a cup-shaped valve 
element 56, the end wall of which is engaged by the piston 42 of the 
actuator 38 acting through a reinforcing button 58. Thus, the return 
spring 48, the spring locator 50 and the valve element 56 are all carried 
by the actuator 38, which is in turn carried by the inner cylindrical 
member 18. 
During normal operation, the inner cylindrical member 18 is secured to the 
outer cylindrical member 20 so that the cylindrical members 18 and 20 move 
with one another and are prevented from moving relative to one another. In 
the embodiment illustrated in FIG. 2, the inner and outer cylindrical 
members 18 and 20 are releasably secured to one another by a mechanical 
linkage generally designated by the reference numeral 60 and better 
illustrated in FIGS. 3-5. The inner cylindrical member 18 includes a 
plurality of apertures 61 and the outer cylindrical member 20 includes a 
plurality of apertures 62 substantially in alignment with the apertures 
61, enabling the controlled fluid to flow into contact with the actuator 
38, so that the actuator 38 can sense the heat of the fluid. An additional 
aperture 63 defined in the inner cylindrical member 18 includes a neck 
portion 64 and a circumferentially extending slot 65. The outer 
cylindrical member 20 includes a circumferentially extending slot 66 
generally in alignment with the slot 65 and having a portion which is in 
alignment with the neck portion 64. A pin 68 (FIGS. 4 and 5) having a head 
70 extends through the slots 65 and 66 and projects radially outwardly 
therefrom, with the head 70 being positioned in the slot 66 and in 
engagement with the inner surface of the outer cylindrical member 20. 
Thus, it can be seen that the pin 68 prevents relative axial movement 
between the inner cylindrical member 18 and the outer cylindrical member 
20. A coil spring 72 is connected to the pin 68 and extends 
circumferentially around the outer surface of the outer cylindrical member 
20 to an anchoring peg 74 secured to the outer surface of the outer 
cylindrical member 20. A pivot pin 76 is mounted in the outer cylindrical 
member 20 from which it projects radially for pivotally receiving an 
arcuate lever member 78 which extends back to the pin 68 and includes a 
hook portion 80 for engaging the pin 68 and maintaining it in a position 
in the slot 66 which lies below a solid portion of the inner cylindrical 
member 18 so that relative axial movement between the inner cylindrical 
member 18 and the outer cylindrical member 20 is prevented. The hook 
portion 80 underlies the pin 68, and the arcuate lever 78 is biased 
upwardly by a spring 81 connected at one end to the arcuate lever between 
the pivot pin 76 and the hook portion 80 and at the other end to the 
shoulder 22. 
A fail-safe temperature-responsive release device, which is responsive to a 
predetermined temperature above the normal operating range of the valve 
10, can take the form of a miniature, auxiliary actuator 82, such as a 
wax-filled element, for producing a positive movement in response to the 
temperature. The actuator 82 is mounted on a tab 84 projecting radially 
outward from the outer cylindrical member 20. The tab 84 can be struck out 
from the wall of the outer cylindrical member 20, or other suitable 
mounting arrangements can be provided. The auxiliary actuator 82 includes 
a projection 86 and an externally threaded guide 88 for receiving a nut 90 
to secure the auxiliary actuator 82 to the tab 84. A piston 92 is mounted 
for reciprocation within the threaded guide 88, and engages the top of the 
arcuate lever 78 so that it can move the lever 78 downward against the 
bias of the spring 82 to disengage the hook portion 80 from the pin 68. 
In the normal operation of the valve 10, the temperature-responsive 
actuator 38 senses the temperature of the liquid in which the valve 10 is 
mounted, since the liquid flows into contact with the actuator 38 through 
the apertures 61 and 62 in the inner cylindrical member 18 and the outer 
cylindrical member 20, respectively. When the temperature of the liquid 
exceeds a first predetermined value, the wax in the actuator 38 melts and 
expands, thereby forcing the piston 42 from its unactuated, retracted 
position to its actuated, extended position. The extension of the piston 
42 acts through the button 58 to move the valve element 56 into engagement 
with the seat 16, and, at the same time, compresses the return spring 48 
between the spring locator 50 and the snap ring 46. If slightly greater 
temperatures than the predetermined temperature occur, the wax expands 
farther and the piston 42 extends farther from the guide 44. However, 
since the valve element 56 has already engaged the valve seat 16, the 
piston 42 can move no farther toward the valve seat 16. Instead, the 
overtravel of the actuator is accommodated by the movement of the actuator 
38 upward within the inner cylindrical member 18 against the bias of the 
overtravel spring 40. When the excess temperature dissipates, the 
overtravel spring 40 moves the actuator 38 back toward the valve seat 16 
until the annular projection 36 engages the flange 32 on the inner 
cylindrical member 18. When the temperature of the liquid falls below the 
predetermined value, the wax cools and contracts, and the return spring 48 
expands, thereby causing the valve element 56 to push the piston 42 to its 
retracted position. 
If the valve should fail to function, so that it remains in its unactuated, 
retracted position despite the rise of the temperature of the fluid above 
the first predetermined value, the temperature of the fluid can continue 
to rise. If the temperature of the fluid rises above a second 
predetermined value, which is higher than the first predetermined value, 
and which is at the threshold of temperatures which are likely to be 
severely damaging to the engine, the wax in the auxiliary actuator 82 
melts and the piston 92 extends. This extension moves the arcuate lever 78 
downward so that the hook portion 80 is clear of the pin 68. The coil 
spring 72 then pulls the pin 68 circumferentially through the slots 65 and 
66 until the pin 68 lies below the neck portion 64 of the additional 
aperture 63 in the inner cylindrical member 18. In this position, the pin 
68 no longer prevents relative axial movement between the inner 
cylindrical member 18 downward with respect to the outer cylindrical 
member 20, so that the overtravel spring 40 moves the inner cylindrical 
member 18 downward with respect to the outer cylindrical member 20 and 
thereby moves the valve element 56 into engagement with the valve seat 16. 
Thus, a fail-safe mechanism is provided for the valve 10 to prevent damage 
to the engine. In this embodiment of the invention, if the reason for 
valve failure can be determined and corrected, the mechanical linkage 60 
can be reset and the valve 10 reused. 
In an alternate embodiment of the invention, which can be seen from FIG. 6, 
the auxiliary actuator 82 and the linkage 60 are replaced by a fail-safe 
temperature-responsive release device in the form of a pin or rivet 94 or 
other element of heat softenable or heat fusible material. The pin 94 can 
be pushed through aligned openings 96 and 98 defined in the inner 
cylindrical member 18 and the outer cylindrical member 20, respectively, 
until the end of the pin 94 projects from the other side, whereupon it is 
flattened to secure the pin in the openings and to secure the inner 
cylindrical member 18 to the outer cylindrical member 20 to prevent 
relative axial movement therebetween. 
When the temperature of the surrounding fluid exceeds the second, higher 
predetermined value, the pin 94 fuses or softens, so that the inner 
cylindrical member 18 is free to move axially with respect to the outer 
cylindrical member 20 under the bias of the overtravel spring 40, thereby 
allowing the valve element 56 to engage the valve seat 16. Although in the 
embodiment shown, the heat fusible or softenable material takes the form 
of a pin or rivet 94, it is understood that the inner cylindrical member 
18 could be secured to the outer cylindrical member 20 by an annular bead 
of the heat fusible or softenable material or that one or more tack welds 
of such material can be provided between the inner cylindrical member 18 
and the outer cylindrical member 20. Moreover, other configurations of the 
heat fusible or softenable material may be employed. 
Although it is apparent from the foregoing that the embodiments of the 
present invention disclosed herein provides significant advantages, it is 
understood that various changes and modifications may be made without 
departing from the spirit and scope of the present invention as recited in 
the appended claims and their legal equivalents. For example, the valve 
element 56 can be provided with a configuration, whereby it engages a 
valve seat when it is in its retracted position and opens to permit flow 
through the seat when it is in its extended position.