US3357252A - Temperature responsive force transmitting device - Google Patents

Description

Dec. 12, 1967 s. VERNET 3,357,252

TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE Filed May 4, 1966 2 Sheets-Sheet 1 INVENTOR.

'sery l'us Verne) A rom 5Y5 Dec. 12, 1967 s. VERNET 3,357,252

TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE Filed May 4, 1966 2 Sheets-Sheet'Z United States Patent 3,357,252 TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE Sergius Vernet, Yellow Springs, Ohio, assignor to Antioch College, Yellow Springs, Ohio, a corporation of Ohio Filed May 4, 1966, Ser. No. 554,258 13 Claims. (Cl. 73368.3)

This invention relates to temperature sensitive motion transmitting devices or thermal sensitive elements and is more particularly directed to a device of this character having a greatly improved means for providing a fluid tight seal for the thermal expansion material and having novel construction features which permit the development of an extremely small diameter thermal element.

The present application is a continuation-in-part of my co-pending United States patent application Ser. No. 215,- 720 and now abandoned. Several responsive elements are now widely used as a means for energizing a wide variety of components as a function of changes in ambient temperature. Generally, they comprise a casing having a thermal expansion material contained therein, a closure cap or guide providing a bore, a diaphragm or seal interposed between the expansion material and the cap, and a power member or piston guided for movement within the bore and bottomed on the seal. When the temperature of the expansion material is raised to a predetermined point, the material expands and this expansion is transmitted through the seal to the power member which is thereby caused to move extensively from the bore.

Heretofore several responsive elements have generally been formed in two parts wherein outwardly extending flanges of an upper and lower casing are used to sandwich the peripheral lip of the boot therebetween to maintain the boot in its proper position within the casing. A column member is then fitted over the out turned flanges of the casing elements and is then peened down or pressed down snugly on top of the flange of the upper casing element to positively secure the casing elements together. Due to the necessity for the outwardly extending flanges in order to secure the peripheral lip of the boot within the casing, the thermal responsive element has been substantially larger in diameter than has been found to be desirable. Thermal responsive elements having such outwardly extending flanges may be referred to as having a so-called horizontal seal. Many uses of thermal responsive elements, however, are required to have a minimum diameter which requirement is in direct conflict with the necessity for having outwardly extending flanges on the upper and lower casing elements. Accordingly it would be highly desirable to provide a means for eliminating the outwardly extending flanges and consequently minimizing the size of the thermal responsive element.

Also, the life of thermal responsive elements heretofore employed in the art has not been entirely satisfactory, particularly in those instances in which the elements are subjected to the forces of highly pressurized water. The reasons for the undesirably short life of these elements is largely twofold. First, ineflicient seals permit the expansion material to seep out of the casing with continued element use. Second, and much more importantly, pressurized water acting on the exterior of the element at the cap and around the guide, forces its way past the cap and seal and into the chamber containing the thermal expansion material. The entering of water into this chamber may considerably alter the operating characteristics of the element and may, in time, prevent the element from operating at all.

I have found that seal loosening is generally caused by movement of the power member relative to the casing of the thermal sensitive element. When the power member moves extensively with respect to the casing, the seal or diaphragm is forced tightly against the piston guide. However, when the power member moves retractibly with respect to the casing, the inner end of the power member acts against the diaphragm or seal to pull the seal away from its normal seated position against the power member guide, and water seeps into the casing through the cracks formed between the metal-to-metal contacting members of the unit.

I have devised a means for preventing loosening of the seal as a consequence of reciprocal movement of the power member. Generally, my invention resides in the provision of a guide having a depending boss extending into the casing which boss has a groove formed in the side wall thereof for receiving a complementary lip formed on the diaphragm or. seal. The diaphragm or seal lip is maintained in compression between the side wall of the boss and the side wall of the casing, so a portion of the seal is always urged into the groove in a depending boss. Loosening of the seal as a result of extension and retraction of the power member is effectively obviated in this manner.

I have also discovered that seal leakage may be caused I by contraction or expansion of the seal or diaphragm as a result of exposure to very hot or cold temperatures. I have devised a means for maintaining the seal in good sealing relation with the casing, the piston guide, and the piston itself which effectively obviates the problems heretofore encountered under such conditions. In addition, I have found that by forming the piston guide of sintered material or a liquid permeable material, liquid trapped between the piston and the boot or water which has seeped into the casing can emerge through the guide. It is therefore a principal object of my invention to provide an improved temperature responsive force transmitting device.

It is also an object of my invention to provide a thermal sensitive force transmitting device having a greatly reduced diameter.

It is another object of my invention to provide thermal sensitive element which is so designed as to prevent seal leakage. 7

Another object of my invention resides in the provision of a thermal sensitive element having means for preventing movement of the sealing portion of a boot or diaphragm as a consequence of reciprocal movement of the power member.

Another object of my invention is directed to the formation of a power member guide of a liquid permeable material to obviate trapping of liquid in the boot by allowing liquid to pass freely through the permeable material.

Also, one of the primary reasons for designing the thermal sensitive element in the manner set forth above is to reduce the overall diameter of the unit. The usual type of thermostat with the flange for sealing the guide to the cup adds considerably to the diameter of the unit and this new design obviates this undesirable characteristic.

These and other objects, features and advantages of this invention will be more clearly understood from the following description and the associated drawing wherein reference numerals are utilized in designating an illustrative embodiment and wherein:

FIGURES l, 2 and 3 are vertical sectional views through a temperature responsive force transmitting device in the process of assembly;

FIGURE 4 is a vertical sectional view through a completed temperature responsive force transmitting device constructed in accordance with my invention;

FIGURE 5 is a vertical sectional view through another embodiment of my invention;

FIGURE 6 is a vertical sectional view through another improved form of thermal sensitive units;

FIGURE 7 is a vertical sectional view through a cup type thermal sensitive power unit; and

FIGURE 8 is a vertical sectional view through that form of my invention which employs a guide formed of a water permeable material.

Referring initially to FIGURE 4, a cylindrical casing 10 is formed of a metal or suitable heat conductive material and has an inturned annular flange 11 formed at one end thereof and defining an aperture 12. A metal disk 13 is seated upon the flange 11 and serves, in turn, as a seat for a resilient disk seal 14. This method of sealing one end of a temperature responsive: force transmitting device is well understood by those skilled in this art and does not constitute part of my invention. In fact, the casing 10 could be formed with a closed end at the base so that the disk and seal 13 and 14 would not be necessary.

An expansion material 15 is contained within the easing 10 and also needs no detailed explanation to those skilled in the art. It generally comprises a wax substance which may be impregnated with a metallic powder and which will expand when its temperature has been raised to a predetermined point.

My invention is more specifically directed to the means for sealing the upper end of the causing through which the power member or piston 16 moves. Also, by sealing the boot within the casing according to my invention, the entire thermal power unit can be formed of a greatly reduced diameter and consequently can be utilized for heretofore unintended applications.

In FIGURE 4, a guide 17 is fitted within the upper end of the casing and is maintained in its proper position by an annular inturned flange 18 which is rolled or crimped over the outer end face 19 of the guide 17. The guide 17 has a side wall 20 which tapers inwardly from the end face 19 thereof. A boss 21 depends from the inner end face 22 of the enlarged diameter portion of the guide 17, and a bore 23 extends centrally through the guide 17 and serves as a guide for the power member 16. A resilient boot 24 is formed of rubber or like materials and extends across the interior of the casing 10 and into the lower portion thereof. Note should be made of the fact that the term seal will hereafter often be used to encompass not only such seals as the boot 24 but also to encompass diaphragms or combination diaphragm plugs which are fainiliar to those skilled in the art. The thermal sensitive element illustrated in FIGURE 4 does employ a boot, but this is only one form of thermal sensitive elements, and many forms are well known to those skilled in the art which could employ my invention in equally as satisfactory a fashion.

The boot 24 has an annular lip 25 formed at the upper end thereof which is fitted between the inner side wall 26 of the casing 10 and the side wall 27 of the depend? ing boss 21. A rounded groove 23 is formed circumferentially about the upper end of the boss 21 and receives an annular head 29 formed at the upper end of the lip 25. A thin walled section of the boot 24 extends upwardly into. the tapered crevice formed between the side wall 20 and the inner side wall 26 of the casing 10, so that a fluid tight seal is formed between the casing 10 and the guide 1 7. A bore 30 is formed within the boot 24 and re? ceives the lowermost end of the power member or piston 16. The type of element illustrated in FIGURE 4 is a squeeze element and derives its name from the manner in which the piston 16 is forced to move extensibly from the guide 17. When the expansion material 15 has its temperature raised to a predetermined critical point, the material will expand and expansion of this material will act to compress the side walls of the boot around the lower end of the piston. The lower end of the piston 16 tapers, as at 31, to a point, so that the squeeze of the side walls by the expansion material 15 tends to force the piston 16 upwardly within the bore 23. This squeeze effect acts to extensibly move the power member 16 from the guide 17 Various means are provided for returning the piston- 16 to the position illustrated in FIGURE 4 upon cooling of the material 15, and such means may, of course, comprise a simple spring acting against the outer end of the piston or against a collar mounted on the piston. Such means are well known in the art and are not here illustrated or further described. Regardless, means are pro vided for returning the piston 16 to the position illustrated in FIGURE 4. Such retractible movement of the piston 16 normally acts to pull the boot 24 downwardly within the casing 10 and such continued pulling of the boot acts over a period of time to cause seal failure and to permit the seepage of water into the interior of the casing where the expansion material 15 is continued.

By forming the boot 24 with a bead 29 at the upper end of the lip 25, such pull down of the boot 24 is effectively resisted.

It is important to understand that the lip 25 of the boot 24 is maintained in position between the casing wall and the side wall of the boss 21 in a compressed state. Also, the thin walled portion 25a is tightly wedged be tween the side wall 20 and the inner wall of the casing. Such compression and wedging is attained by the manner in which the unit is assembled which is clearly illustrated in FIGURES l, 2 and 3. Referring to FIGURE 1, it will be observed that the guide 17, piston 16, and boot 24 have been assembled as a single unit. The boot 24 has a thin walled outwardly extending integral flange 32 extending from the upper end of the boot adjacent the bead 29. In an unstressed condition, the outer diameter of the boot 24 at and adjacent to the lip 25 is somewhat greater than the inner diameter of the casing 10. As a result, when the boot, guide, and piston are forced into the casing, the lip 25 is put under compression to provide a positive seal between the guide and the inner wall of the casing. Also, since an outwardly extending flange is not required in order to secure the resilient boot within the casing, a thin cylindrical casing, such as the casing 10 may be employed for containing the thermal element. In additron, it may be noted that the inner surface of the cylindrical casing, such as the casing 10 may be employed for containing the thermal element. In addition, it may be noted that the inner surface of the cylindrical casing 10 may be a substantially smooth wall such that the cost of forming the casing can be considerably reduced over casings heretofore used which have been specially constructed for the purpose of supporting the resilient boot therein. a

As shown in FIGURE 2, the flange 32 will be bent upwardly as the guide and boot are moved into the easmg. The thin walled flange 32 will become wedged between the tapered side wall 20 of the guide 17 and the inner wall 26 of the casing 10, and the outer edge thereof will finally be clipped otf as the uppermost end of the guide 17 is forced into position within the casing 10. As a result, the thin walled section of the 'boot 24 will become tightly wedged between the guide and the casing, and a positive seal will be formed there also. Once the guide is in its proper position within the casing, the end wall of the casing is crimped over the guide to positively maintain the guide in its proper seated position.

An important feature of my invention consists in the fact that the thin walled rubber section is put under very high compression as the guide and boot are forced into the casing. Still further, the action wherein a portion of the boot is squeezed tightly between the guide in the casing is important, in that it tends to make the rubber fill all crevices to provide a perfect seal. Also, the uses of a thin rubber section for the seal minimizes the undesirable consequences resulting from the fact that the metal and rubber parts have a different coefficient of expansion.

It should also be understood that the flange 32 need not be formed at right angles to the axis of the boot but can be in the form of a cone. Also, an inwardly extending bead can be formed on the inner surface of the casing at a point adjacent the recess 28 of the inserted guide to aid in compressing the seal at this point after assembly.

In FIGURE 3, I have illustrated a slight modification of my device in which a diametrically enlarged head 17a is formed on the guide 17 and is adapted to seat upon a shoulder a formed at the upper end of the casing 10. In this embodiment of my invention, the guide would simply be forced into the casing until the head 17a is seated upon the shoulder 10a, and the outermost end of the casing would then be crimped over the outer end face 19 of the guide. In FIGURE 3, I have shown the device just prior to' the crimping or rolling operation.

The boot 24 is formed with an annular upstanding ring 35 formed integrally therewith which is adapted to extend up within the annular well 33. It is important to note however that the cross-sectional outer diameter of the upstanding ring 35 is somewhat greater than the cross-sectional inner diameter of the well 33 so that when the piston 16 is fitted through the guide 17 and into the boot 24 it will act to put a compression load on the ring 35. This embodiment of my invention is particularly adapted to withstand considerable temperature variances. Since the lip 25 and ring 35 are maintained in compression expansion of the rubber as a result of increases in ambient temperature would only act to increase the effectiveness of the seal. On the other hand, when a thermal sensitive power unit is subjected to very cold conditions the seal normally tends to pull away from the outer walls and tighten against the piston 16. In this embodiment of my invention the tendency for contraction will only act to increase the effectiveness of the seal between points. A

and B. Contraction of the rubber between points A and B will act to cause the boot to fit more tightly on the boss 21 and thereby increase the effectiveness of the seal at that point. The lip 25 and ring 35 will be under compression and the contraction of the rubber at those points would only tend to decrease the compression force somewhat. The ring 35 and lip 25 however are relatively thin walled and the rubber contraction at these points would only be negligible and not impair the effectiveness of the seal in any substantial degree.

I have also recognized the fact that there may be some water seepage along the wall. of the piston 16 adjacent the guide 17 and that some of this water may become trapped between the end face 34 of the guide and the upper end of the boot 24. Such water trapping can be substantially obviated by preventing the boot 24 from pulling away from the end face 34 of the boss 21. The structure illustrated in FIGURE 6 achieves this end. A thin walled collar 36 having an end face 37 depends from the end face 34 of the boss 21 and defines an extension of the bore 23. The collar 36 has a side wall 38 which diverges outwardly toward the end face 37 thereof and the upper end of the boot 24 is fitted around this collar. It will be observed that in this device the effective seal between the collar 36 and an adjacent portion of the boot 24 will become greater as the downward movement of the piston 16 tends to pull the boot 24 downwardly within the casing 10. Of course, it is sufficient if the diverging wall of the collar 36 constitutes any annular section of the collar and it is not essential that the wall diverge all the way from the end face 34 to the end face 37.

In the embodiment of FIGURE 7, a guide 40 is seated upon the shoulder 10a formed at the upper end of the casing. The guide 40 is substantially the equivalent of the guide 17 heretofore described but for the fact that it has an elongated hollow boss 41 extending upwardly therefrom. A depending boss 42 is formed intgerally therewith and has a side wall 43 which is spaced from the straight side wall of the casing 10. An annular segment of the wall 43 is tapered as at 44 to diverge outwardly from the end face 45 toward the end face 46 to form a recess. A diaphragm 47 extends across the interior of the casing 10 and has an upturned lip 48 with a head 49 formed on the upper end thereof which bead is received within the recess. A resilient plug 50 having an enlarged diameter base portion and a reduced diameter top portion is fitted within a complimentarily shaped section of the bore 51 and seats upon the diaphragm 47. An anti-chafe disk 52 seats, in turn, upon the plug 50 and serves as seat for the power member 53. The configuration of the lower end of the bore 51 and the plug 50 serve to amplify the motion of the diaphragm 47 caused by expansion of the material within the casing 10 so that an increase in piston stroke can be achieved in a manner well known in the art.

In the embodiment of FIGURE 8 I have shown a temperature responsive force transmitting device which is much like that shown in FIGURE 4 but for the fact that. a guide 55 is provide in place of the guide 17 which is formed of a water permeable material. In the illustration the guide is formed of a sintered metal but many different types of water permeable materials would likewise be suitable. The advantage of having the guide formed of a water permeable material is that water trapping at the inner face between the guide and the boot is obviated.

Attention is directed to the fact that in the thermal power unit of this invention, a recess has been formed in the depending boss and that this feature in combination with the fact that the boot or its equivalent serves to provide a positive fluid tight seal which will not readily be rendered less effective by continued reciprocal movement of the piston. Also the method of forming a vertical seal has made possible the greatly miniaturizing of thermal power elements without reducing the effective force control of those elements.

It will be understood that various modifications and combinations of the features of my invention may be accomplished by those versed in the art without departing from the spirit or scope of my contribution to the art, and I desire to claim all such modifications and combinations as properly come within the scope of my invention.

I claim as my invention:

1. A temperature responsive force transmitting device comprising:

a casing having a side and an end wall and containing an expansion material;

a guide member forcibly fitted Within one end of said casing and being held axially stationary therein by the force fit between the guide and the casing, said guide having a depending portion spaced from the side wall of said casing,

a seal extending across the interior of said casing having a lip interposed between said depending portion of said guide and the said side wall of said casing and being held in position substantially only by the force exerted on said lip by said depending portion of the guide and the side wall of the casing;

a power member guided. for movement within said guide and bottoming on said seal;

wherein said lip is firmly maintained between said side wall of said casing and said depending portion of said guide and wherein a portion thereof completely fills said recess.

2. A temperature responsive force transmitting device in accordance with claim 1 wherein said casing has an opened end opposite said end wall and wherein a shoulder is formed about the inner side wall of said casing adjacent said open end thereof and facing outwardly of the interior of the casing and wherein said guide is seated upon said shoulder.

3. A temperature responsive force transmitting device in accordance with claim 1 wherein said casing and said guide are cylindrically formed and wherein seal and lip comprise a resilient boot which completely fills the space between said depending portion of said guide and said side wall of said casing.

4. A temperature responsive force transmitting device in accordance with claim 1 wherein a portion of said casing is fitted over at least part of the exposed end of said guide to maintain said guide within said casing.

5. A temperature responsive force transmitting device in accordance with claim 1 wherein said guide has a tapered side wall and wherein said lip of said seal is interposed between said tapered side wall and the side wall of the casing.

6. A temperature responsive force transmitting device comprising:

a casing containing a thermal expansion material;

a guide fitted within and closing an end of asid casing and having a boss depending therefrom;

said boss having a side wall and an end face;

a seal extending across the interior of said casing having a lip interposed between said depending boss and the said side wall of said casing;

a recess formed about said side wall of said boss;

2. guide bore formed within said guide and extending through the end face of said boss;

a recess formed within said end face around said bore; and

a power member guided for movement within said bore and bottoming on said seal;

wherein said lip is maintained in compression between said boss and said side wall of said casing and wherein portions of said seal fill each of said recesses.

7. A temperature responsive force transmitting device constructed in accordance with claim 6 in which said guide and the said boss are formed of a water permeable material.

8. A temperature responsive force transmitting device comprising:

a casing having a side and an end wall and containing an expansion material;

a guide fitted within and closing one end of said casing and having a depending boss spaced from the side Wall of said casing;

a seal extending across the interior of said casing having a lip interposed between said depending boss and the said side wall of said casing;

a power member guided for movement within said guide and bottoming on said seal;

said depending boss having a side wall and an end face;

wherein at least a segment of the said side wall of said boss diverges outwardly toward the said end face thereof;

and wherein said lip is maintained in compression between said side wall of said boss and said side wall of said casing.

9. A temperature responsive force transmitting device constructed in accordance with claim 8 in which said guide and the said boss are formed of a water permeable material.

10. A temperature responsive force transmit-ting device comprising:

a casing having a side and an end wall and containing an expansion material,

a guide fitted within and closing one end of said casing and having a depending portion spaced from the side wall of said casing,

said guide being formed of a water permeable material,

a seal extending across the interior of said casing having a lip interposed between said depending portion of said guide and said side wall of said casing,

a power member guided for movement within said guide and bottoming on said seal, and

a recess formed around the eripheral side wall of said depending portion,

wherein said lip is firmly maintained between said side wall of said casing and said depending portion of said guide, and wherein a portion thereof completely fills said recess.

11. A temperature responsive force transmitting device comprising:

a casing having a side and an end wall and containing an expansion material,

a guide fitted within and closing one end of said casing and having a depending portion spaced from the side Wall of said casing,

said guide being formed of a water permeable material,

said guide having a tapered side wall,

a seal extending across the interior of said casing having a lip interposed between said tapered side wall of said guide and the side wall of said casing,

a power member guided for movement within said guide and bottoming on said seal, and

a recess formed around the peripheral side wall of said depending portion,

wherein said lip is firmly maintained between said side wall of said casing and said depending portion of said guide, and wherein a portion thereof completely fills said recess.

12. A temperature responsive force transmitting device in accordance with claim 1 wherein said casing has a generally smooth cylindrical side wall and wherein said lip of the seal is held in position between the smooth cylindrical side wall and the depending portion of the guide.

13. A temperature responsive force transmitting device constructed in accordance with claim 12 wherein said depending portion of said guide converges to a smaller diameter at the end of said guide most closely adjacent the end of the casing containing the expansion material.

References Cited UNITED STATES PATENTS 7/1940 Verne-t 73-368.3 X 7/1962 Wagner 73--368.3

Claims (1)

1. A TEMPERATURE RESPONSIVE FORCE TRANSMITTING DEVICE COMPRISING: A CASING HAVING A SIDE AND AN END WALL AND CONTAINING AN EXPANSION MATERIAL; A GUIDE MEMBER FORCIBLY FITTED WITHIN ONE END OF SAID CASING AND BEING HELD AXIALLY STATIONARY THEREIN BY THE FORCE FIT BETWEEN THE GUIDE AND THE CASING, SAID GUIDE HAVING A DEPENDING PORTION SPACED FROM THE SIDE WALL OF SAID CASING. A SEAL EXTENDING ACROSS THE INTERIOR OF SAID CASING HAVING A LIP INTERPOSED BETWEEN SAID DEPENDING PORTION OF SAID GUIDE AND THE SAID SIDE WALL OF SAID CASING AND BEING HELD IN POSITION SUBSTANTIALLY ONLY BY THE FORCE EXERTED ON SAID LIP BY SAID DEPENDING PORTION OF THE GUIDE AND THE SIDE WALL OF THE CASING; A POWER MEMBER GUIDED FOR MOVEMENT WITHIN SAID GUIDE AND BOTTOMING ON SAID SEAL;

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