US 3776457 A
A fail-safe device for thermostatic valves featuring a support structure with an aperture providing a by-pass passage around the valve, and a plug fitting within and blocking the by-pass passage and having a retaining structure of temperature softening material, stiff while at a colder temperature to retain the plug in the aperture and softer while at a hotter temperature to permit the plug to be removed from the orifice if the valve is closed although retaining the plug in the aperture when the valve is open.
Description (OCR text may contain errors)
i v United States Patent 1 [111 3,77
Cardi 1 t, 1973  FAIL-SAFE DEVICE FOR THERMO STATIC 1,692,773 11/1928 Friedman 137/74 X VALVES  Inventor: Paul Cardi, 1375 Park Ave., Primww Examiner-William Wayner Cranston, 2 2 Attorney-Robert E. Hillman  Filed: Oct. 1, 1971 211 App]. No.: 185,665  ABSTRACT A failsafe device for thermostatic valves featuring a support structure with an aperture providing a by-pass 2363256113332 passage around the valve and a plug fitting within and  we. 0. 5 34 93 blocking the by pass passage and having a retaining I structure of temperature softening material, stiff while at a colder temperature to retain the plug in the aper- 4 ture and softer while at a hotter temperature to permit  References Cited the plug to be removed from the orifice if the valve is UNITED STATES PATENTS closed although retaining the plug in the aperture 3,498,537 3/1970 Wong 236/34 when the valve is open. 2,895,677 7/1959 Drapeau 236/34 2,985,180 5/1961 Grayson 137/74 6 Claims, 5 Drawing Figures PATENTED DEC 75 FIG I BLOCK ENGINE 2| RADIATOR FIG 4 FAIL-SAFE DEVICE FOR THERMOSTATIC VALVES BACKGROUND OF THE INVENTION The cooling of automobile engines is frequently accomplished by a forced circulation system in which a cooling fluid is pumped from an engine block where .it has picked up heat, through a radiator where it loses its heat, and thence back to the engine block. In order to accomplish rapid warm up of the engine block on starting, these systems frequently control the flow of cooling fluid to the radiator by a thermostatic valve-While the cooling fluid is cold the valve remains closed and prevents flow through the radiator, but in response to an increased temperature in the cooling fluid the valve.
opens and permits=flow through the radiator and back to the engine block. Such thermostatic valves occasionally through malfunction. remain .or become closed even when the cooling fluid is hot with the result that the engine block overheats and is damaged. A- primary object of my invention is accordingly to provide a failsafe by-pass for such valves in the event of valve malfunction and a further object isto prevent damage to engines through overheating as a result of valve malfunction.
SUMMARY OF THE INVENTION I have recognized that in their normal operation thermostatically controlled valves of the type described are at some colder temperature closed with a high pressure difference across the valve (namely, when the engine is starting up), and are at some hotter temperature open with a small pressure difference across the valve (namely, when the engine is warmed up). Neither pressure nor temperature alone can, therefore, beused as a criterion for the malfunction of the valve. The malfunctioning valve is characterized by the occurrence of high pressure at the hotter temperature. Accordingly,
my invention features a support structure with an'aperture providing a by-pass passage around a thermostatically controlled valve, and a plug fitting within and blocking the by-pass passage and having a retaining structure of temperature softening material, stiff while at the colder temperature to retain the plug in the aperture against the thrust of the high pressure and softer while at the hotter temperature to permit the plug to be removed from the orifice by the thrust of the high pressure although retaining the plug in the aperture against the thrust of the lower pressure.
In a preferred embodiment the aperture is an elongated slot in a thin wall and the retaining structure is a flange integral with the plug, tapering inthickness from one end of the slot to the other,anchored on its thicker end and having reinforcing ribs extending across the plug.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects and features will appear from the following description of the preferred embodiment of the invention taken together with the attached drawings thereof in which: I
FIG. 1 is a schematic diagram showing the flow channels in a cooling system employing the invention.
FIG. 2 shows an embodiment of the invention as it is installed adjacent to the thermostatic valve of the system of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment will be described referring first to FIG. 1 where pump 10 drives cooling fluid through engine block 12 whence it circulates in part through channel 14 and thermostatically controlled valve 16' (supposing the fluid to be hot and valve 16 consequently open) to channel 18 and thence to radiator 20 from which the fluid returns by channel 22 to pump 10. Channel 21 provides a direct return to pump 10 when valve 16 is closed. Fail-safe device 24 is connected in parallel with valve 16. Turning now to FIGS. 2 and 3, thin-wall support structure 30 supports valve 16 between channel 14 and channel 18. Valve 16 (shown open in FIG. 3 as it would normally be in the hotter temperature condition) provides an annular passage 32 through which coolant flows from channel 14 to channel 18. The construction and operation of thermostatically controlled valves of the type shown is well known and need not be further described here.
Structure 30 has an elongated slot aperture 36 (shown in additional detail in FIG. 5) providing a bypass passage around valve 16. Plug 40 which is advantageously made of polyethylene fits within aperture 36, thereby blocking it to the flow of cooling fluid. Plug 40 has an integral flange 42 made of a temperature softening material such as polyethylene which serves as a re taining structure holding plug 40 in place in aperture 36 against the thrust of pressure acting from channel 14 towards channel 18. Flange 42 is tapered in thickness from one end to the other as shown particularly in FIG. 4 and is anchored to structure 30 at its thicker end 44 by rivet 46. Flange 42 is advantageously reinforced by ribs 48 extending across plug 40'widthwise.
In normal operation with the engine block 12 and cooling fluid at a colder temperature as during start-up, passage 32 of valve 16 would be closed and the action of pump 10 would produce a certain pressure drop between channel 14 and channel 18, although there would be no flow to radiator 20. At the colder temperature supposed, the polyethylene material of which flange 42 is composed would be stiff and strong and would retain plug 40 in aperture 36 against the thrust of the pressure differential from channel 14 to channel 18. After running for a while, engine block 12 and the cooling fluid would become hot and the material of flange 42 would at the hotter temperature become softer and weaker, but, supposing normal operation, thermostatic valve 16 would have opened passage 32 to permit flow to radiator 20 with the result that the pressure drop from channel 14 to channel 18 would be small. Flange 42, even though softer and weaker at this hotter temperature, would retain plug 40 in aperture 36 against the reduced thrust of the now small pressure difference. If however through malfunction, valve 16 should close passage 32 while the cooling fluid is at the hotter temperature, the pressure difference from chanagainst the thrust of this higher pressure. The thinner portion 43 of flange 42 would give-way and plug 40 would be thrust out of aperture 36 into channel 18. Rivet 46 would, however, retain the plug-flange structure and prevent it from circulating through the cooling system. The now open aperture 36 would permit a flow of cooling fluid to the radiator and back to the engine block, thus preventing damage from excessive heating.
in the preferred embodiment described, the valve opens at about 190 F, the plug is polyethylene, 1.5 in. long (around the curve) and 5/32 in. wide. The flange is H32 in. wide, and tapers from 3/32 in. thick at its thicker end to one-sixteenth in. at its thinner end. The three reinforcing ribs are H16 in. thick. The flange when cold (say 120 F) retains the plug against a 5 psi pressure differential and softens and releases it against such a pressure at a temperature of 225 F.
The invention can be readily adapted to other pressures and release temperatures by changing the dimensions and shape of the retaining structure and choosing materials softening at higher or lower temperatures as appropriate. The data and methods for such adaptations will be well known to those skilled in the art and need not be further elucidated here.
1. in a cooling system with a pump for circulating cooling fluid and a thermostatically controlled valve for regulating the flow of said cooling fluid, said system operating normally to have when said fluid is at a first,
colder temperature said valve closed to block flow of said fluid through a passage with a high pressure across said valve, and when said cooling fluid is at a second, hotter temperature to have said valve open to permit flow of said fluid through said passage with a lower pressure across said valve, a fail-safe device to prevent damage if said valve through malfunction should become closed when said cooling fluid is at said hotter temperature comprising:
a thin-walled support structure with an elongated slot-like aperture providing a bypass passage around said valve, plug fitting within and blocking said by-pass passage, and having a retaining structure of temperature softening material stiff while at said colder temperature to retain said plug in said aperture against the thrust of said high pressure and softer while at said hotter temperature to retain said plug in said aperture against the thrust of said lower pressure and permit said plug to be removed from said aperture by the thrust of said higher pressure,
said retaining structure being integral with said plug and tapering in thickness from one end of said slot to the other.
2. The device of claim 1, wherein said flange is anchored to said support structure at its thicker end.
3. The device of claim 2, wherein said flange has reinforcing ribs extending across said plug widthwise.
4. The device of claim 1, wherein said material is an organic plastic.
5. The device of claim 4, wherein said organic plastic is polyethylene.
6. The device of claim 3, wherein said plug is 1.5 in. long and 5/32 in. wide, wherein the flange is H32 in. wide and tapers from 3/32 in. thick at its thicker end to one-sixteenth in. at its thinner end, wherein there are three reinforcing ribs each 3/16 in. thick and wherein said plug and flange are made of polyethylene.