US2463921A - Valve mechanism and control means - Google Patents

Description

March 8, 1949. L. R. TITCOMB VALVE MECHANISM AND CONTROL MEANS Filed Sept. 50, 1942 Iii/632157;

Patented Mar. 8, 1949 UNITED STATES PATENT OFFICE VALVE MECHANISM AND CONTROL MEANS Lee R. Titcomb, Chicago, Ill.

Application September 30, 1942, Serial No. 460,310

1 Claim. 1

This invention relates to valve mechanism and has to do also with thermal responsive control means adapted for use with the valve mechanism.

My invention is directed to the provision of valve mechanism for controlling flow of fluid under pressure from a source of supply to a container or receptacle, responsive to conditions of temperature or pressure in the latter and in such manner as to maintain the temperature and pressure in the container or receptacle constant, maintain constant the pressure under which the fluid is delivered to the container or receptacle, or to deliver to the container or receptacle a measured amount of the fluid. I provide a valve mechanism of the character referred to which is of comparatively simple but rugged construction well suited to exacting conditions encountered in its use, and is capable, in certain of its forms, of accurate adjustment for assuring the desired pressure of delivery of the fluid.

My invention also includes thermo-responsive means and valve mechanism particularly suitable for use with such thermo-responsive means, the latter being capable of withstanding severe temperature conditions and cooperating with the valve mechanism for actuating the latter responsive to slight variations in temperature. Further objects and advantages of my invention will appear from the detail description:

In the drawings:

Figure l is a central vertical sectional view through valve mechanism and associated thermally responsive control means, embodying my invention, certain parts being shown in elevation and certain other parts being broken away;

Figure 2 is a fragmentary view, partly in section, of the valve mechanism and control means, showing a second modification of the valve mechanism;

Figure 3 is a view similar to Figure 2 but showing a third modified form of valve mechanism; and

Figure 4 is a diagrammatic view of the valve mechanism of Figure 3 and the thermally responsive control therefor mounted on a tank containing a solution adapted for bluing steel.

Referring first to Figure l, I shall now describe the thermal actuated control, indicated generally by the reference numeral IQ, for the valve mechanism. This control mechanism II) has an outer cylindrical casing H which is closed at its lower end, as at 12, and open at its upper end. This casing l l is preferably made of metal, preferably steel, stainless or otherwise. Conveniently, the upper end of this casing H has exterior threads 15 and is screwed into a supporting frame 14, but it may be secured to frame M in any other suitable known manner.

Within the casing II and resting against its bottom is a spherical steel button or cap l6. This button or cap l6 has a short central shank I! which fits loosely inside the cylindrical bore l8 of a ceramic tube 20, which is ground off square at its ends and fits loosely within the casing H. A flat steel button or cap 2| seats on the upper end of tube 2!] and is kept in place by its short shank 22 which fits loosely within the cylindrical bore 18. The purpose of this flat cap 2| is to distribute the load evenly upon the whole surface of the upper end of the tube 20, which distribution would not result ordinarily if the upper surface of tube 20 were not ground flat. The even distribution of the load reduces the danger of fracturing of the ceramic tube 20. Spherical button or cap it fitting against the bottom edge of tube 20 cooperates in the same manner as cap 2| in equalizing the distribution of the load on tube 20.

A steel cup 23 with a rounded bottom rests on the top of the fiat cap 2 l. The inside diameter o the cup 23 is substantially larger than the head 25 of a cap screw26 threaded into the lower end of a solid steel cylindrical thrust rod 21 which has a loose, sliding fit within the casing II. A coiled steel compression spring 28, disposed about screw 26, is confined between the bottom of rod 21 and a Washer 30 seating at its inner portion on head 25 of screw 26 and, at its outer portion, on the upper end of cup 23. Spring 28 is prestressed by means of the cap screw 26.

A screw 3| threaded through the right hand or short arm of a lever 32, for adjustment, bears against the upper end of thrust rod 21. While a lever of the first class is shown, and is preferable for the specific arrangement illustrated, a lever of the second class may equally well be employed with slight rearranging of the other parts. The lever 32 is pivoted close to screw 3] on bearing trunnion 33 which is supported at each end in the adjacent channel shaped part of the frame I l.

The casing I l, the rod 21 and the screw 26 are preferably all made of the same material which, for example, may be common steel which is both sturdy and inexpensive. Common steel has a coefficient of thermal expansion of approximately 11 10' per degree centigrade in the range of 0-100 C. The casing H and rod 21 may be of any desired length to fit the needs of the installation. In the present case the casing II and rod 2! are long enough to allow dissipation of heat suificient to assure that the frame l4 and lever 3 32 remain at substantially room temperature. The overall length of these members has otherwise no practical effect on the operation of the control except as hereinafter described.

The ceramic tube 25 has a thermal coefficient of expansion of approximately 1.8'75 10 per degree centigrade which is about one-sixth that of common steel. It is to be understood that other materials than common steel may be used for the thrust rod 21, casing ii, and screw 25; the same may be said for tube 2il-a ceramic tube is not the only usable material. The important factor is that there should be a substantial difference between the coeflicient of expansion of the tube 25 and of the rod 2'7, casing H and screw 26. It is important, however, to choose the materials for durability and constancy of thermal coefiicients of expansion within the range of the temperature involved. The caps l and 2|, cap 23, adjusting screw 3! frame It, bearing 55 and. lever arm 32 may be of any suitable material and preferably are made of ordinary low carbon steel.

Any movement of rod 2'? with respect to casing II, and hence frame it, acts to operate the lever 32, or to permit operation thereof, by pressure or release of pressure on screw 3!. The movement is multiplied by the long arm of the lever 32 according to the laws of leverage; a mechanical advantage of 27-1 is illustrated in Figure 1. Adjustable engaging screw 35 at the left hand end (long arm) of lever 32 presses against a col lapsible metal bellows 31 and reflects, on an in creased scale, the motion of rod 27.

The valve housing, indicated generally at 35, has a threaded inlet 38 and a chamber 40. A valve seat member M is threaded into an opening 42 in the bottom of the housing 35 and has a passage 43. The threaded outlet t l leads to an apparatus, container, or receptacle, for receiving the fluid from valve housing 35. A valve member 45 cooperates with seat member ti and is secured to plate 4?, conveniently by being screwed thereinto by means of an hexagonal portion 48. An expansible metal bellows 39 and a guide cylinder 50 are secured to the upper face of plate ll. The bellows 49 is secured, at its upper end, to the lower side of flange 5| of a tubular fitting 52- screwed into a stepped and dished cover 5 3 which screws into the upper end of housing 35.

.Cylinder 50 houses a coil compression spring 53, of appropriate strength, confined between plate 41 and a flange 553a adjacent the lower end of an adjusting tube 59 extending through fitting 52 and defining a passage 55. Tube 55 extends upwardly through a, flange 55a, of cover 5 1, which flange is at the upper end of fitting 52 and extends a slight distance radially inwardly beyond the fitting 52 so as to hold tube 59 out of contact, circumferentially, with fitting A tongue and groove connection 39 between flange 54a and tube 59 holds the latter against rotation while permitting axial adjustment thereof. Tube 59 screws through a spur gear 59?) mounted for rotation on an annular rib 5% on the upper face of cover 5 5, and confined against axial movement between rib 54b and an annular rib 55c, at the under face of a disc fi ld screwed into the upper end of cover 54. Disc 55d is provided at its under face with a central recess 54c which opens through a port 56 into a chamber 63 defined by a hollow boss 62 on the top of disc 5 2d, to the upper end of which boss 62 the lower end of bellowsv 37 is suitably secured. A ball valve 5'! normally seats in the upper end of port 55 and controls communication between bellows 49 and bellows 3 through passage 55 of adjusting tube 59, recess 5% and port 56. Suitable gaskets are disposed between cover 5 3 and the upper end of housing 35, and between an interior shoulder of cover and disc 540, as shown.

The interior of the large bellows i5 is connected to the chamber 55 of the housing 35 through a restricted inlet duct 55 in plate 15?, provided with a strainer 65 at its outer end. The duct 58 may open into the interior of the bellows at at any other convenient place as, for example, through the fitting 52, but the location of duct 58 and screen 55 below the bellows allows impurities to drop away by gravity. Further, by being disposed in the line of liquid flow the tendency is to wash the screen free of impurities. A thrust member or post 55 rests at its lower end upon ball valve 5? and is secured at its top to the inside of the top of the smaller bellows 3?. A drain tube 55 is threaded into a hole in the side of the hub 52 and serves to drain the bellows 37. As mentioned earlier, adjustable engaging screw 35 in lever arm 32 bears on the head of the thrust member 6 3 by way of the top of the collapsible bellows 31.

Gear 5% meshes with a pinion filo. secured on the lower end of a rod 5! mounted for rotation through a stuffing box Gib in disc 55d. A knob 5 ie is secured on the upper end of rod 5| and provides convenient means for rotating it and thereby rotating gear 59b for effecting axial adjust ment of adjusting tube 59. Downward movement of tube 55 compresses spring 53 thereby increasing its effective resistance to contraction of bellows t9, and upward movement of tube 59, permitted by recess 54c, has the opposite effect. That provides simple and highly efficient means for controlling the opening of valve 55, as will be explained more fully presently.

The frame It is shown as being integrally connected to the valve housing 35 as by webs 55 and 51.. This mode of construction is not essential. It is required that the frame hold the stationary parts rigidly in fixed relation to each other. The supporting frame Id and the valve housing 35 may be separate parts so long as they remain in fixed positions with respect to one another.

Referring more particularly to Figure 1, the valve 45 is shown as closed against the seat of member 4!, in which position it normally is held by compression spring 53 supplemented by the spring action of the bellows 49. Fluid which enters the housing fills the chamber 45 and passes through the strainer ti] and inlet duct 58 to the inside of the bellows 59. When the fluid pressure inside chamber Ml and bellows 49 is in equilibrium the valve 55 is closed. This condition exists when the passage 55 is closed by ball valve 5? and thrust bar 64, and when the main valve port 43 is closed by valve member 45. Since the pressure inside and outside of the bellows is then equal there is no tendency for the fluid pressure to collapse it.

When screw H is not subjected to pressure by the thermo-responsive control means, the long arm of lever 32 is free for upward movement. The pressure of the fluid inside the larger bellows raises the ball valve 57 from its seat and the fluid escapes from bellows 49 into and partially fills bellows 3i, and flows out of the latter bellows through'the drain tube 55. Since the duct 58 is quite restricted relative to port 56, the former having a diameter of about /64" and the latter having a diameter of about for example, fluid escapes from bellows 49 at a considerably greater rate than fluid can enter that bellows through duct 58. Consequently, the action of the fluid pressure on the exterior lower end surface of the bellows 49 causes it to contract lengthwise. Since the upper end of bellows 49 is fixed, the lower end thereof moves upwardly. Cylinder within the bellows 49 cooperates with flange 5| to limit the maximum extent to which this bellows can be contracted. Contraction of the bellows 49 withdraws valve member 45 to a greater or less extent from its seat and permits the flow of fluid through the housing and out of the discharge outlet 44. When the ball valve 51 has a diameter of approximately three-sixteenths (a) of an inch and the duct 58 and port closed position and holding it in that position so long as screw 3| is under pressure. Bellows 49 then fills with pressure fluid, the interior pressure and the exterior pressure to which this bellows is subjected become equalized andvalve 45 is returned to its closed position by the action of spring 53, supplemented by the spring action of bellows 49, and is held there until ball valve 51 is again opened.

The form of valve mechanism of Figure 2 may also be used, in conjunction with lever 32 and :5

the thermo-responsive unit Ill for supplying a relatively hot fluid or liquid, from a suitable source of supply, to a bath or body of fluid or liquid for maintaining the latter at a predetermined minimum temperature. In such case, the tube may discharge to atmosphere or into the bath or body of fluid. When the temperature of the body of fluid or liquid tends to drop, the thermo-responsive unit I!) contracts slightly and causes downward movement of the long arm of lever 32, by the resultant pressure exerted against screw 3| (Figure 1). That opens ball valve 510., permitting escape of pressure fluid from bellows 49 with resultant opening of valve 45 and discharge of relatively hot fluid into the body of fluid in which unit Ill is immersed, raising the temperature thereof to the desired minimum, at which time unit Ill expands relieving the pressure on screw 3|, and spring 99 returns ball valve 51a. to its closed position.

The valve mechanism of Figure 3 is similar to that of Figure 2, except that the thrust post 34 is in direct contact with ball valve 51, which seats in the upper end of port 56a, as in Figure 1, and a light coil compression spring 53a, extending downward through cylinder 50, is confined between plate 41 (shown in Figure 1) and flange 5|a of fitting 52a screwed into cover l54. The spring 530. is not essential and may be omitted in cases where the spring of bellows 49 is sufficient to hold valve 45 closed, and the tube 65a may discharge to atmosphere or to any other suitable point of discharge.

In Figure 4, the vat 10, shown in section, has a frame 1| indicated as a cover. This illustration is largely diagrammatic. The cover 1| has a short section of pipe 12b threaded therein to which is threaded the valve housing 35 of a valve mechanism similar to that of Figure 5. The inlet of the valve housing 35 is connected by a pipe 16 to a source of supply of water under pressure, and the pipe 122) acts as a discharge duct from the valve housing to the bath. The thermal actuated control I0 is inserted through a hole in the cover 1| and extends at its lower end into the bath 14. An electric heating element 13 projects into the salt solution 14 to heat the bath to the boiling point. Assume for illustrative purpose that it is a predetermined maximum temperature of the salt bath 14 which it is desired to control for bluing of steel articles immersed in the solution. This maximum temperature may be selected in the range of from 300 to 500 F. for example.

The operation of the thermal actuated control is as follows: As soon as a temperature greater than the predetermined maximum is reached, due to the heat input of heating element 13 and the increased boiling point being caused by increased concentration due to evaporation, the expansion of the tube II will cause it to lengthen in a downward direction since it is fixed at its upper end. This will permit the ceramic cylinder 2|] and steel rod 21 to slide downwardly with the lowering bottom |2 of the tube since parts 20 and 21 have a sliding fit within tube The ceramic cylinder 20 has a much smaller coeflicient of expansion than tube H and therefore expands less. Furthermore, cylinder 20 is heated principally by radiation of heat from tube I and by conduction through spherical cap It and a minor amount of contact with the wall of tube Hence it takes a short interval of time for the temperature to equalize the parts. Rod 21 and tube II will expand also because the region above the surface of the bath will be filled with water vapor.

Therefore, these various rates and degrees of expansion result in a lowering of the end surface 15 of rod 21 with respect to the upper end of the tube ll. That means that the end surface 15 of rod 21 starts to move away from its contact with screw 3|. The fluid pressure against valve member 51-as was above described when the valves 51 and 45 were closedis such that it will then force up valve member 51, thrust bar 64, bellows 31, screw 36 and lever 32 in such a manner as to cause screw 3| to follow the top surface 15 of rod 21 for at least a short distance. The degree of movement of screw 3| is determined by the amount of movement necessary for opening the valve 51. Since the movement of valve 51 corresponds to that of the long arm of lever 32, th movement of screw 3| needs to be only small. Consequently the rise in temperature of the s solution will result in a slight lowering of the screw 3| with lowering of the upper surface 15 of rod 21. The opening of valve 51 an amount less than five ten-thousandths l of an inch results in the opening of valve 45. Therefore a change of temperature of around one-half a degree centigrade will cause valve 45 to be opened. Response to such a small change in temperature is obtained by the interaction of several factors -the difference in the coefficients of expansion of tube and cylinder 2|], the length of cylinder fill, the time differential in the heating of these tubes and the mechanical advantage of the lever 32.

The ceramic cylinder 2!] will, of course, expand. It does not start as soon, and has a much lower coefiicient of expansion than tube H, but it will expand and thus raise end surface 15 of rod 21 upward toward the screw 3|. Since a considerable amount of cooling water may be let in past 1 the valve 45, when the predetermined tempera.- ture is exceeded only by a. small amount, there will be but a short space of time before tube M will begin to contract. The ceramic cylinder will subsequently contract also. The contraction of tube II will cause the cylinder 20 and rod 21 to rise again. When the temperature of the fluid is lowered to the proper operatin temperature again, the tube will have so shrunk that the end surface 55 of rod 2'! will have perforce contacted and forced up screw 3 I.

That means that the lever 32 at its left end will be forced down. Therefore screw 36 will press on the top of expansible bellows 31 and thrust rod 84 will force valve 57 shut. When valve 5'5 is shut, water will begin to fill up the inside of the large bellows a9 and the pressure in side and outside bellows as will become equal again. ihe spring action inherent in bellows 43, supplemented by the action of the compression spring 53a, if used, will expand bellows 39 and seat valve 45', thus shutting off the flow of water.

The more extensive and more rapid fluctuations in the length (expansion and contraction) of the tube i! are always followed by a slower and less exaggerated expansion and contraction of the ceramic cylinder 2%. Since the ceramic cylinder 26' is a factor, as is tube it, in the positioning of surface with respect to the fixed top of tube H and screw 3!, surface l5 depends upon the interaction of both tube i l and cylinder 26 to determine its location for a given situation.

The purpose of spring 28 which is prestressed by screw 26 is to act as a safety device. That is to say, it protects the instrument from rough handling and also provides against excessive stress on the ceramic cylinder or other parts due to excessive contraction of tube H.

To illustrate this, consider the device shown in Figures 3 and 4. Assume that the water pressure in the main feeding valve housing has a pressure of pounds per square inch. Also assume that valves 5'? and are in closed position and that th salt solution is at, but not exceeding the predetermined maximum temperature. adjusting screws 3i and 35 will have been adjusted earlier for just this condition of equilibrium. That is, they will be positioned in such a way that they will firmly bear on rod 21 and thrust rod 8 8 respectivelyso that opening of r valve 5? by the water pressure against it will be resisted at the right hand end of the lever which bears-by means of screw 3lagainst surface 15 of rod 21. (It is feasible if desired, to calibrate the thermal actuated control for action at various temperatures. Such calibration may be applied to the adjusting screw 3|, for example, but preferably to screw 36.)

Now if tube ll contracts further from any cause, that will mean that ceramic cylinder 20 and rod 27 will be compressed between lever arm 32 and the bottom end l2 of tube II. The lever 32 cannot swing further about its bearing 33 since the left end of the lever arm is firmly pressed against thrust rod 8d and valve 51 which is firmly and solidly seated. In order to prevent the ceramic tube 20 from being crushed by excessive contraction, prestressed spring 28 is added between rod 2! and ceramic tube 2!). Excessive contraction of tube I! then will not crack ceramic cylinder 20 but will force spring 28 to compress. Spring 28 is prestressed suificiently so that when all parts of the valve and thermal control are in an equilibrium or normal operating. condition the fluid pressure acting The Y 8 against valve 5-1 will not causeit to open by compressing. spring 28 through lever arm 32. With fluid pressure of 4'0pou-nds per square inch in the mains, spring 28 of the illustrated device is preloaded. to approximately 125 pounds.

If the control mechanism is to be used at high temperatures it is advisable to put the spring at the upper end of the rod 21 out of range of said heat. The rod 21 with its spring 28 and the cap 23 could be inverted to adapt the device quickly for use at higher temperatures.

Now the fact that my valve mechanism and thermal actuated control have been used in cooperation is not to indicate that that is the scope of their usefulness. The scope is greater and" is not to be. limited by the above specific illustrations. The pilot controlled valve mechanism of my invention is peculiarly adapted for thermostatic oontrol'or other control where the movement of the element responsive to the particular variable is' sinall or minute. Thus a relatively large flow of fluid is turned on and off by a very minute motion of the valve 51. The. dilution of a salt bath is but one example. The blendingof fractions or ingredients in petroleum distillation is another example.

The valve mechanism, in its various forms disclosed herein, with or without the thermostatic control, may be applied to control of various fluids such as air-or steam or other gases, vapors or liquids or mixtures of the same. The thermostatic element may be employed to operate switch contacts instead of a control valve. However, there is a particular'relation between the valve mechanism shown herein and a positive expansion type of thermostat, in that the thermostat must hold the pilot valve 5'! against the pressure of the liquid, when valve 45 is closed. Hence a positive force is required although a very small movement is involved. Damage to the parts under the conditions of abnormal movement in the closing direction is obviated by the prestressed, spring 28 above described.

Briefly, the usefulness and applicability of my invention is extensive, and many modifications and changes are possible without departing from its scope and spirit as set out in the appended: claiml Ina valve mechanism, a housing having an inlet and an outlet, a bellows Within said housing afiixed at one end thereto having a constantly open restricted inlet and an outlet, a main valve carried by the other end of said bellows controlling said housing outlet, a tubular member extending into said one end of said bellows establishing communication between the latter and said? bellows outlet, a compression spring within said bellows confined between said other end of said bellows and said tubular member, means operable exteriorly of said housing for adjusting said tubular member lengthwise thereby varying the extent of compression of said spring, and valve means controlling flow of fluid through said bellows outlet.

LEE R. TITCOMB.

REFERENCES CITED The following references are of record inv the file of this patent:

UNITED STATES PA'IE'NTS Number Name Date 342,275 Walters May'18, 1886 (Gther references on following page) Number Number Name Date Robertshaw et a1. Sept. 22, 1931 Grifiith Dec. 5, 1933 Earle July 24, 1934 Payne Aug. 21, 1934 Ray June 18, 1935 Sandvoss Sept. 10, 1935 Bridwell Feb. 6, 1940 Mery Oct. 7, 1941 Bender Nov. 11, 1941 Anderson Apr. 21, 1942

Images