US2998725A

US2998725A - Thermo-actuator

Info

Publication number: US2998725A
Application number: US675735A
Authority: US
Inventors: James F Scherer
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-04-08
Filing date: 1957-08-01
Publication date: 1961-09-05
Anticipated expiration: 1978-09-05

Description

SePt- 5, 1961 J. F. scHERER THERMO-ACTUATOR Original Filed April 8, 1954 INVENTOR. dlgys F.' SCHE/em D55 JARD/Man@ Eo/NsoM 2am/XM HIS ATTORNYS United States Patent 2,998,725 THERMO-ACTUATOR t James F. Scherer, K206 Stanton Ave.,'Terrace Park, Ohio Original application Apr. 8, 1954, Ser. No. 421,925, now Patent No. 2,810,290, -dated Oct. 22, 1957. Divided and this application Aug. 1,1957, Ser. No. 675,735

3 Claims. (Cl. 73-368) This invention relates to temperature control devices,

and particularly to thermo-actuators of the type which produce a thrust of considerable magnitude within a narrow temperature range for enabling positive and accurate control to be effected thereby.

This case is a division of my earlier application Serial No. 421,925 led April 8, 1954, and issued on October 22, 1957 as Patent No. 2,810,290, and it is incorporated herein in full as part of the disclosure.

One ofthe objects of the invention is to provide an improved form of thermo-actuator which is more reliable andlonger-lived than presently known devices of this v character.y

Another object of the invention is to provide a thermoactuator incorporating improved means for positively sealing oir the heat expansible medium from the surrounding uid.

' Another object of the invention is to provide a temperature controlled actuator in which the heat expansible material is embraced within a self-contained, sealed cap- Sule.

Another object of the invention is to provide a temperature controlled actuator which is'simple in construction and eflicient in operation. With these `and other objects in View which will become apparent from the following description, the invention includes certain novel features of construction and combination of parts, the essential elements ofwhich are set forth in the appended claims, and two forms or embodiments of the invention will hereinafter be described with reference to the drawings which accompany and `form a part of this specification.

In'the drawings:

ice

Patented Sept. 5, k196:1

cap 20.l The body and cap should be constructed of a" material Vhavingl high heat conductivity such as brass, copper, aluminum and the like so that the variation in heatY to" which the device -is subjected may readilypass" through the housing into the capsule. The chamber y14 may be of any shape but is preferably cylindrical lori spherical, and the shape of the capsule 12 will be of the same shape thereof and of a size to fit in and ii-ll said chamber 14. The outside diameter of the capsule 12 will be substantially equal to the diameter of the chamber -14 so that it will completelyiill the chamber at temperatures below the operating range in which the heat expansible material 110 is in its unexpanded condition. Hence, any significant expansion of the material 10 will be transmitted to the piston 22 which is mounted for sliding movement in a bore 24 provided in cap 20. The piston 22 is provided.

with a stem 26 which is slidably mounted in a bore 28. extending through the end of the cap. A pin 30, whichV is equal in diameter to the stem 26, is also mounted within the bore 28, in the end of the stem 26, and transmits motion from the pistonto the apparatus which is to bel the capsule 12 continues, through excessive heating to expand after the piston has reached the end of the bore 24, a portion of the capsule may enter the recess- 34 upon continued expansion of the material 10 and prevent any damage to the thermo-actuator. t

The thermo-actuator device shown in FIG. 1 is actually much smaller than indicated by the drawing, it .being shown on an enlarged scale herein to clearly illustrate the details of the'various constructable :features thereof.

- The device is assembled by placing the capsule 12, which FIG. 1 is a cross-sectional view illustrating one embodii ment of the invention.

FIG. Z is a cross-sectional View showing another embodiment of the invention.

In the accompanying drawings, I have illustrated two forms orl embodiments of the invention, both of which incorporate a self-contained, sealed capsule embracing the heat expansible material which generates the thrust produced by the device when the operative range .of temperatures is reached. In each case, the heat expansible material contained in the capsule is characterized byl its rapid change in volume over a narrow temperature range so as to provide for positive actuation of the device to be controlledat a predetermined temperature. A suitable material for use within the capsules is described in U.S. Patent No. 2,259,846 granted on October 2l, 1941.

In the construction shown in the embodiment of FIG. l of the drawings, the temperature responsive material is contained within the sealed capsule 12 formed of resilient material such as natural or artificial rubber or synthetic resins which will withstand the repeated expansion and contraction of the material 10 and will, by virtue of the restorative force acting on the hereinafter described piston 22, tend to restore it to its normal shape. Its normal shape is shown in FIG. l and, from this normal shape, it is deformed by the expansion and contraction of said material 10. The heat responsive material 10 may be injected into the capsule 12 through a small hole provided in the wall thereof which may thereafter be sealed shut by any of the various expedients well known in the art.

against the bottom of the recess provided thereforrin the' body`18. The lip 38 is then spun over as indicated in FIG. l to securely fasten the body andcap together to constitute a unitary housing 16 when the'capsule 12 is embraced within the cavity or chamber 14. s

Although not shown herein, a return spring, which may form part of the apparatus controlled by the thermo# actuator device, is utilizedvto return the piston 22toits normal position as shown in FIG. l upon contraction of the material 10 after the temperatureV hasy returned 4to normal.` The material forming the wall ofthe capsule 12 will, of course, due to its elasticity, tend to return t0,` the position yshown upon contraction ofy the heat'V expansible material 10, but the contractive force thus exerted may not be suicient to completely return the capsule to its normal shape without the assistance of external restoring means. In this connection it is to be realized that the wall of the capsule should be kept as thin aspossible consistant with the strength requirements thereof so as to not interfere with the transmission of heat from the housing 16 into the heat expansible material 10 contained within the capsule.

A more rapid transfer of heat from the exterior of the device vinto the heat expansive material contained therein may be achieved by means of the construction in FIG. 2. As herein shown, a body of heat expansible material 40 is embraced within a capsule 42 formed of wax, or a like material, such as certain types of polyethylene` glycol or other materials which, though rigid and solid at normal temperatures, are adapted to melt and remain in the liquid state within the operating temperature rangeof the thermo-actuator device, thereby allowing the material formerly enclosed therein to actuate the piston of the thermo-actuator device. The liquid into which the wall of the capsule is transformed upon an elevation in temperature should be compatible with the heat expansible material 40 so that no undersirable` eects willbe produced' on the latter materialby the melting of the capsule sheath. Here again the capsule is in the fornrof a self-contained unit which may be readily handled at normal or slightly sub-normal temperatures; and which may be conveniently inserted in the device in the course of assembly, the same as the capsule 12 in the form of the device shown in FIG. 1. In the case of the gelatin type capsule, it will, of course, become necessary to seal the device against the escape of liquidor gas from the chamber 44 within which the capsule 42 is received. Toward this end, the piston 46 is provided with circumferential grooves receiving O-rings 48 formed of resilient material and being of conventional construction. An additional O-ring 49 is seated in an annular groove provided in the bottom of the` bore 50 provided in the cap 52 within which the piston is slidable. The O-ring 49, upon full expansion of the capsule, will engage against the outer face 54 of the piston and further guard against the ingress or egress of liquid or gas from the outside of the device into the chamber 44, or vice versa. The joint between the cap 52 and body 56 may be sealed by a large O-ring 58 received within an annular groove provided in the bottom of the recessrin the body. Hence, when the cap 52 is inserted in the body andthe lip 59 spun over, the ring 58 will be tightly compressed and form a tight seal to guard chamber 44 against the ingress or egress of either liquid or gas. In all other respects the thermo-actuator device shown in FIG. 2 is like the device shown in FIG. l.

While I have describedy my invention in connection with certain specific forms or embodiments thereof and have used, therefore, certain specific terms 4and language herein, it is to be understood that the present disclosure is illustrative rather than restrictive and that changes and modifications may be resorted to without departing from the spirit or scope of the claims which follow;

Having thus described my invention, ,what I claim as newA and useful, and desire to secure by United States Letters Patent, is:

1. A temperature responsive actuator comprising a body memberI having a recess formed therein, a cap member having a corresponding recess formed therein, means for securely fastening said cap member to said body with' saidrecesses facing one another to thereby form a housing having a chamber therein, a piston mounted for sliding movement within a bore in one of said members with the inner end of said piston forming a part of the wall of said chamber, a shoulder formed on the wall of made of a material which becomes liquid at normal operating temperature of the device in said chamber, an expansible material in said capsule capable of undergoing a substantial change in volume with a change in temperature to effect movement of said piston, and means for sealing said piston to prevent the passage of liquid to or from said chamber.

2. A temperature responsive actuator comprising a body member having a hemispherical recess formed therein, a cap member having a corresponding recess formed therein, means for securely fastening said cap member to said body member with said recesses facing one another to thereby form a housing having a spherical chamber therein, a piston mounted for sliding movement within a bore in one of said members with the inner end of said piston forming a part of the spherical wall of said chamber, a shoulder formed on the wall of the bore, a stern projecting from a complementary shoulder on the outer end of the piston, an integral sealed capsule made of a material which becomes liquid at the normal operating temperature of the device in said chamber, an expansible material in said capsule capable of undergoing a substantial change in volume with a change in temperathe bore, a stem projecting from a complemental shoulder ture to effect movement of said piston, and means for sealing said piston to prevent the passage of liquid to or from said chamber.

3. A temperature responsive actuator comprising a body member having a cylindrical recess formed therein, a cap member having a corresponding recess formed therein, means for securely fastening said cap member to said body with said recesses facing one another to thereby form a housing having a cylindrical chamber therein, a piston mounted for sliding movement within a bore in one of said members with the inner end of said piston forming a part of the wall of said chamber, a shoulder formed on the wall of the bore, a stem projecting from a complementary'.` shoulder on the outer end of the piston, an integrated sealed capsule made of a material'which becomes liquid at the normal operating temperature of the device in said chamber, an expansible material in said capsule capable of undergoing a substantial change in volume in accordance with a change in temperature to effect movement of said piston, and means for sealing said piston to prevent the passage of liquid to or from said chamber.

References Cited in the le of this patent UNITED STATES PATENTS 251,355 Gibbs Dec. 27, 1881 406,138 Hobson July 2, 1889 1,294,484 Krynitzky Feb. 18, 1919 1,484,816 Derby Feb. 26, 1924 2,115,502 Vernet Apr. 26, 1938 2,593,238 Albright Apr. l5, 1952 2,736,604 Albright Feb. 28, 1956 FOREIGN PATENTS 345,050 France Sept. 28, 1904 167,547 Switzerland May 16, 1934