US3121532A - Remote bulb thermostats - Google Patents

Description

Feb. 18; 1964 Filed Aug. 31, 1961 J. E. FLECKENSTEIN REMOTE BULB THERMOSTATS 4 Sheets-Sheet 2 uem w INVENTOR. JOSEPH E. FLECKENSTEIN ATTORNEYS.

Feb. 18, 1964 J. E. FLECKENSTEIN REMOTE BULB THERMOSTATS 4 Sheets-Sheet 3 is:

Filed Aug. 51, 1961 INVENTOR.

ATTORNEYS.

1964 J. E. FLECKENSTEIN 3,

REMOTE BULB THERMOSTATS Filed Aug. 51, 1961 4 Sheets-Sheet 4 E t g JOSEPH E. FLECKENSTEIN ATTOR N EYS.

United States Patent 3,121,532 RED/{GTE BULB THERMGSTATS loseph E. Fieclrenstein, Milwaukee, Wis, assignor to Johnson Service (Iompany, Milwaukee, Wis, a corporation of Wisconsin Filed Aug. 31, 1 61, Ser. No. 135,329 3 Claims. (Cl. 23632) This invention relates to improvements in remote bulb thermostats.

It is a general object of the present invention to provide an improved remote bulb thermostat of the pneumatic type and containing a leakport. In those designs of pneumatic thermostats which contain leakports the instrument sensitivity is conventionally varied by mechanical means such as by the use of a sliding contact, or by a ring mechanism such as shown in prior Patent No. 2,523,213. These prior designs utilize a number of moving major components. All of these devices must have a feedback lever, and an input lever. Prior devices have required the use of at least one additional major moving member to permit mechanical amplification of the movement of the feedback diaphragm, such as a second feedback lever, or mechanism of the type described in prior Patent No. 2,523,213, or a link which transmits the input signal from the diaphragm of the temperature sensing element to the flapper lid. In addition to the above, with prior designs there has been no simple and satisfactory way to alter the instrument action from direct acting to reverse acting.

It is a general object of the present invention to provide an improved remote bulb thermostat wherein there is a simple means for varying the instrument sensitivity with out adding an additional major moving component, and wherein there is a simple means for altering the instrument action from direct acting to reverse acting in a manner which minimizes additional possible sources of error in the instrument.

A more specific object of the invention is to provide a remote bulb thermostat wherein the instrument sensitivity is varied by a novel movably mounted leakport assembly, the leakport being movable along the feedback lever to vary the instrument sensitivity; i.e., the change in the instrument output which results per unit change of input.

A further specific object of the invention is to provide an improved remote bulb thermostat wherein the instrument action may be altered from direct acting to reverse acting by changing the position of the mount for the sensing element.

A further object OJ. the invention is to provide an instrument as above described having a movable leakport for varying the instrument sensitivity, the arrangement havin the following advantages over previously tried methods for varying the sensitivity: a minimum number or". major moving components with resulting reduction in friction and error resulting therefrom; simplicity of design in that with a movable leakport there need be only one pivoted member to transmit the input signal to the leakport plus one pivoted member to feed back the output si nal to the leakport; neatness in appearance; reduced cost because of the minimum number of basically simple parts required; increased accuracy of the sensitivity scale in that a slide may be positioned on a scale of approximately 3 inches with an accuracy in the proximity of 1%; desirable scale distribution, the input being increased at the same time the feedback is decreased, whereas with fixed leakports the scale is often extended too much at the low sensitivities and contracted too much at the higher sensitivities; less variation in feedback because in a design with a movable leakport, in order to accomplish a certain sensitivity change, the

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amount of feedback need not be varied as much as in an instrument which has a fixed leakport; and consistent stability, as a design with a movable leakport may be made to be consistently stable and non-oscillatory with greater ease and with greater tolerances, as the feedback need not be varied over as wide a range as would be required in conventional designs.

A further object of the invention is to provide a remote bulb thermostat wherein the novel method of altering the instrument action by reversing the position of the sensing element mount, provides an instrument with greater accuracy as compared with conventional designs which normally contain an additional component such as a lever for altering the direction of the motion produced, such additional components increasing the possibility of undesirable errors which may easily develop at pivots and points of contact. With the present invention the internal friction within the instrument is kept at a minimum.

A further object of the invention is to provide a remote bulb thermostat having means for reversing the position of the sensing element mount so arranged that the set point adjustment may be mounted on the thermostat body instead of on a movable component. in this latter case the set point is difficult to adjust because the instrument output will vary when the set point dial or post is unintentionally contacted by a person attempting to affect the set point adjustment.

With the above and other objects in view, the inven tion consists of the improved remote bulb thermostat, and all of its parts and combinations, as set forth in the claims, and all equivalents thereof. In the accom- ,panying drawings, illustrating preferred embodiments of the invention, in which the same reference numerals designate the same parts in all of the views:

FIG. 1 is a schematic view of the invention showing the relationship of the parts as they would normally be in vertical section through the instrument;

FIG. 2 is a fragmentary sectional view taken on the line 22 of FIG. 1;

FIG. 3 is a rear view of the instrument;

PEG. 4 is a fragmentary sectional view taken on the line 44 of FIG. 3;

FIG. 5 is a fragmentary sectional view taken on the line 5-5 of FIG. 3;

FIG. 6 is a fragmentary sectional view taken on the line 66 of FIG. 3;

FIG. 7 is a fragmentary sectional view taken on the line 7-7 of FIG. 3;

FIG. 8 is a front view of the instrument showing the slidable leakport feature;

FIG. 9 is a top view of the instrument;

FIG. 10 is a bottom View of the instrument;

FiG. 11 is a sectional view taken on the line llll of FIG. 8 showing the mount for the sensing element head in a direct acting position;

FIG. 12 is a view similar to the lower portion of FIG. 11 showing the sensing element head mount in a reverse acting position;

FIG. 13 is a rear view of the apparatus of FIG. 11;

PEG. 14 is a view similar to FIG. 13 showing a modified type of mount for the sensing element head wherein the mount positions the sensing element in reverse acting position;

FIG. 15 is a view similar to FIG. 14 showing the modifled mount shifted to the direct acting position;

FIG. 16 is an enlarged fragmentary sectional view showing the valve mechanism in the relay; and

FIG. 17 is a sectional view through the leak port assembly.

Referring more particularly to the drawings, the numeral 2i? designates an instrument case having a front wall 21. Side walls 22, a bottom wall 23 and a top wall 24, which project rearwardly from the front wall, define the margins of an enclostue Within which components of the instrument may be housed. A temperature sensing element such as a remote bulb 25 (see FIG. 1) is connected by a capillary tube 26 with a sensing element head 27 having a diaphragm 28 therein adapted to act on a temperature actuated rod 29 which acts on an input lever 30 on one side of its pivot 31, as shown in FIG. 1, the arrangement shown in FIGS. 1 and 3 being such that the instrument action is direct acting-that is the instrument increases its output upon increases in the sensed temperature. The temperature sensing element head includes a mounting plate 32 (see FIG. 3) having a mounting wing 33 with bolt holes 34 through which bolts 35 may be projected to secure the mounting plate 32. to holes 34' in a shoulder 36 on the instrument case, as shown in FIG. 11. The wing 33 is separated from the main portion of the mounting plate by a slot 37 leaving small connecting portions 38 which act as flexing hinges. The head proper is secured to the mounting plate by four bolts 39.

To reverse the position of the element sensing head 27 to make it reverse acting, the bolts 4% which extend through the clamping plate 41 must be removed or loosened to release the lower end of the capillary tube 26. Then the four bolts 39 are removed to free the head 27 from the mounting plate 3 2. Next the mounting bolt plates 35 are removed and the mounting plate is reversed from the position of FIGS. 3 and 11 to the position of FIGS. 12 and 13. During such removal, the bolts 34 are re moved from the bolt holes 34 in the shoulder 36, the mounting plate 32 is reversed to the position of FIG. 13, and the bolts 35 are replaced using bolt holes 42 in a shoulder 43 associated with the bottom 23 of the case. Next the head 27 is re-connected to the reversed plate through use of the bolts 3? as shown in FIGS. 12 and 13, and the capillary tube clamping bolts as are tightened. During such reversal, the actuating rod 29 is moved from the hole 4-4 of the case to hole 45 (see PEG. 1), the new position of the parts being illustrated by dot and dash lines in FIG. 1. It is apparent that in this new position the actuating rod 29 acts on the input lever 36 on the opposite side of its pivot 31 so that the instrument is now reverse acting, that is it decreases the output upon increases in the sensed temperature.

A modified Way of shifting the position of the sensing element mount 32, which requires somewhat less effort to make the change, is shown in FIGS. 14 and 15. Here all of the parts are given the same reference numerals as in FIGS. 3 and 11, except that the numerals are preceded by the digit 2. In this form of the invention the mounting plate 232 has opposed wings 233 and 233', each separated from the main body by slots 2 37 and each hav ing the flexing hinge connections 238, the element head 227 proper being mounted midwaybetween the wings 233 and 233.

To change this instrument from direct acting to reverse acting it is merely necessary to first remove the bolts 235 from the holes in the wing 233, to then loosen the bolts 249, and to then shift the mounting plate from the position of FIG. 15 to the position of FIG. 14, the bolts 235 being reinserted in the holes 24-2. During such shifting the actuating stem is of course moved from one aperture in the case to the other aperture, just as is shown in FIG. 1 by the dot and dash lines.

Pivoted near the top of the case on pivots 46 is a feedback lever 47 which may be relatively broad in plan view as shown in FIG. 8, and which extends alongside of the extension portion of the input lever 30 as also shown in FIG. 8. The feedback lever is provided with a longitudinal slot 48. A leakport assembly 4% includes one or more washers 56 on the outer side of the slot, held by a removable clip 5% as shown in FIG. 17, a base portion 51 on the lower side of the slot, a leakport nozzle 52 extending axially of the mounting portions and 51,

and a U-shaped member 53 having a long flexible leg constituting a leakport lid and which normally flexes into closing position with respect to the leakport 52 as shown in FIG. 17. The spaced mounting portions 553 and 51 of the leakport assembly frictionally engage opposite sides of the feedback lever 4-7 therebetween in such a manner that the assembly 49' may be manually slid to a desired position in the length of the slot 48, the frictional engagement being such that the mounting members 58 and 51 will maintain the leakport in a desired position of slidable adjustment. It is this sliding movement of the leakport assembly which is employed for varying the sensitivity of the instrument as will be hereinafter explained.

In FIG. 1 is shown a supply line 66 for air under suitable pressure which leads to a pneumatic relay 61. The relay is illustrated in FIGS. 3, 5, and 11. Supply pressure for the relay enters at port 62 (see FIG. 7). This flows through ducts 63 and 64 (see FIG. 5) into a pilot air chamber 66, the air passing through a filter 67 and restricting orifice, the filter removing small dust particles and preventing them from getting lodged in the small orifice. The pilot air pressure of chamber 66 is communicated through ducts 161 and 162 (see FIG. 4) with the hose 1&3 leading to the leakport assembly 49.

Through the action of the relay, any increase in the pilot pressure will be accompanied by a proportional increase in the control pressure, which pressure is contained within the control air chamber 6%, passageway 69 and chamber 7!) (see FIG. 11). This is the feedback air which acts on the feedback capsule 71. The latter will be moved in response to control pressure changes in a linear movement-pressure relationship. Increases in the control pressure will move the capsule '71 so that its actuating rod 72 acts on an adjustment screw 73 on the feedback lever 47, to rotate the feedback lever about its pivots .6 moving the lever away from the capsule 71. Movement of the feedback lever away from the metallic capsule will tend to increase the clearance between the end of the leakport 52 (FIG. 4) and the leakport lid 53. This is because the leakport 52 will move with respect to the input lever 30, whereas the end of the leakport lid 53 establishes contact with the input lever 30 and therefore cannot move with respect to the input lever. When the leakport is closed by the lid the pressure in the pilot air chamber 66 rises and when air is allowed to escape from the leakport the pressure in chamber 66 falls.

eferring again to the relay mechanism 61, the force exerted by the pilot pressure in the pilot air chamber 66 acting upon the pilot diaphragm 74 (FIGS. 5 and 16) must be balanced by the force of the control pressure in the control air chamber 63 acting upon the control diaphragm 75 plus the force of the relay bias spring 76. The magnitude of the force exerted by the relay bias spring 76 on the control diaphragm 75 determines the value of pilot air pressure required before the control air pressure will begin to increase. The relay ratio is determined approximately by the effective area of the pilot diaphragm 74- to the effective area of the control diaphragm 75.

Should the pilot pressure be increased at 66, an unbalanced condition Will exist momentarily in the relay the exhaust valve 77 will be forced away from the pilot air chamber 66 moving a flapper valve 77 from its annular seat 78' in output plate 78. Supply air will then pass from the supply air chamber 1% through the clearance space around the exterior of the exhaust valve 77 (see FIG. 16) into the control air chamber 68 and into the passageways 69 and and also into the control air line 79 (see FIG. 3). The supply air will continue to flow into the control air chamber until a balanced condition is again restored. Should an unbalanced condition be produced within the relay by a decrease in the pilot pressure, the exhaust valve 77 will move away from the flapper valve 77' preventing communication between chamber 100 and the control air chamber d8, and opening the seal between the top of exhaust valve 77 and the flapper valve. Air will then flow from the control air chamber 68 down through the center of the exhaust valve 77 and into the exhaust air chamber 8i and to the atmosphere through the port holes 81 from exhaust chamber 80 (see FIG. 3). As a balanced condition is again approached, the top of the exhaust valve 77 will begin to seat against the underside of the flapper valve '77, restricting the air flow from the control chamber 68 to the atmosphere.

Summary of Operation When used as a direct acting instrument, as in FIGS. 3, 11 and 15, and as in full lines in FIG. 1, temperature increases will move the input lever 3t away from the metallic capsule 71 tending to increase the pilot pressure and consequently the control pressure. Through the action of the metallic capsule 71 the leakport assembly 49 will be moved in a direction away from the metallic capsule 71 tending to increase the clearance between the leakport 52 and the leakport lid 53. Obviously, the action of the metallic capsule '71 cannot increase the clearance between the leakport 52. and the lea'kport lid to precisely that value which it would have prior to a temerature increase. However, by using a leakport with a high gain, by using a temperature element with a large movement, and by using a high ratio relay, the total movement required at the leakport for a 100% control pressure change can be very small compared to the movement of the input lever. Thus it is apparent that the leakport assembly will be forced to follow almost exactly the movement of the input lever 3d at that point where the input lever 3i} contacts the leakport lid 53 as in FIG. 4. When in the direct acting position a temperature decrease would tend to produce the converse of the above described operations.

When it is desired that the instrument be reverse acting, it is merely necessary to shift the element mounting 32 to the position shown in FEGS. 13 and 14.

The Sliding Leakport Assembly The sensitivity of the instrument may be varied by merely sliding the leakport assembly 49 (see FIG. 8) along the slot 48. There may be a suitable scale along the margin of the slot. Whenever the leakport assembly 49 is near the lower end of the slot 4-8, the sensitivity will be low. Whenever the leakport assembly is near the opposite end of the slot 4 8 the sensitivity will be comparably high.

Set point changes are affected by means of the set point adjustment post 82 which is mounted in a drilled and tapped hole 83 in the instrument body. By rotating this set point adjustment post 82, both the temperature sensing element head 27 and the temperature actuated rod 29 are moved with respect to the instrument body, the head 27 pivoting due to the mounting on the hinge pieces 38 (FIG. 11). An accidental bump or slight pressure on the dial 84, or on the set point adjustment post 32', will not cause large or erratic changes in the control pressure as would be the case if the set point adjustment post were less rigidly mounted. The set point adjustment post 82 is rotated in line with the input lever pivots 31. Thus the change in the set point per degree of rotation of the posts 82 is the same in the direct acting position as in the reverse acting position of the mounting plate 32 or 232.

From the above it may be seen that a very simple and compact remote bulb thermostat has been provided Wherein sensitivity may be varied in a simple and accurate manner by merely lineally sliding the lealrport assembly. It may further be seen that the instrument action may be easily altered to provide either a direct acting or reverse acting instrument by a simple shift in the position of the mounting plate for the sensing elements. it is also apparent that this arrangement has been worked out so that the set point adjustment is nevertheless supported in fixed position on the instrument body, in line with the input lever pivots so that it Works the same in either position of stem 29, the holes 44 and 45 being equally spaced from the pivot 31 (see FIG. 1), and the sensing element mounting plate flexing the same on its hinge strips 38 in either of its positions. The set point adjustment post extends loosely through the lower portion of the lever 39 so as not to interfere with pivotal movement of the lever on the pins 31.

Various changes and modifications may be made without departing from the spirit of the invention and all of such changes are contemplated as may come within the scope of the claims.

What I claim is:

1. in a pneumatic control device having a pneumatic relay with a supply means for air and having an output pressure conduit leading from said relay, means connected with said relay and including a pivoted feedback lever automatically pivotally movable in response to feedback pressure from said relay and also including a conduit having a leakport assembly with a movable lid for controlling the escape or" air from said lealcport to vary the pressure in said output line, a pivoted input lever engageaole with said leakport lid, temperature responsive means for causing pivotal movement of said input lever in accordance with temperature changes, and means movably mounting said leakport assembly including its lid on said automatically pivotally movable feedback lever for simultaneous adjustable movement relative to said feedback and input levers to change the distance from the input lever pivot to the point of engagement of the input lever with said leakport lid and thereby vary the sensi tivity of the instrument.

2. In a pneumatic control device having a pneumatic relay with a supply means for air and having an output pressure conduit leading from said relay, means connecte with said relay and including a feedback lever pivoted to said control device and automatically pivotally movable in response to feedback pressure from said relay, a conduit having a leakport assembly with a movable lid for controlling the escape of air from said leakport to vary the pressure in said output line, a pivoted input lever engageable with said leakport lid, temperature responsive means for causing pivotal movement of said input lever in accordance with temperature changes, means movably mounting said lealiport assembly including its lid on said automatically movable feedback lever for adjustable movement relative to said input lever to change the distance from the input lever pivot to the point of engagement of the input lever with said leakport lid to thereby vary the sensitivity of the instrument, and control means for causing pivotal movement of said feedback lever.

3. In a pneumatic control device having a pneumatic relay with a supply means for air and having an output pressure conduit leading from said relay, means connected with said relay and including an automatic movable feedback lever pivoted to said control device to project in one direction, a conduit having a leakport assembly with a movable lid for controlling the escape of air from said leakport to vary the pressure in said output line, an input lever pivoted to project oppositely of and parallel to said feedback lever and engageable with said leakport lid, temperature responsive means for causing pivotal movement of said input lever in accordance with temperature changes, means mounting said leakport assembly in cluding its lid, on said automatically movable feedback lever for movement longitudinally thereof and of said input lever to change the distance from the input lever pivot to the point of engagement of the input lever with said lealzport lid to thereby vary the sensitivity of the instrument, and control means including a diaphragm in connection with said relay and responsive to feedback pressures from said relay for causing said automatic pivotal movement of said feedback lever.

4. In a pneumatic control device having a pivoted control lever, a temperature sensing element having a lever actuator movable in response to temperature changes, means for mounting said element in a plurality of interchangeable positions whereby the lever actuator may be made to engage on one side of the lever pivot or the other depending upon Whether the instrument is to be direct acting or reverse acting, said mounting means providing for yieldable movement of the sensing element to vary its distance from said lever, and set point adjustment means on the control device having a screw intersecting the axis of the pivot of said lever and engageable with said mounting means for the sensing element to adjust the position thereof.

5. in a pneumatic control device having a pneumatic relay with a supply means for air and having an output pressure conduit leading from said relay, means connected with said relay and including a conduit having a lealcport, a pivoted lever, means between said lever and said leakport for controlling the escape of air from the leakport to vary the pressure in said output conduit in accordance with movement of said lever, a temperature sensing element having an actuating rod, a mounting plate for said element having a mounting wing flexibly connected thereto, and means for mounting said wing in a plurality of interchangeable positions whereby the actuating rod may be made to engage on one side of the lever pivot or the other depending upon whether the instrument is to be direct acting or reverse acting, and a set point adjustment screw mounted on the control device in a position to engage with said mounting plate in either position thereof.

6-. In a pneumatic control device having a supply means for air and having an output pressure conduit, means on said device including a conduit having a leakport, a pivoted lever, means between said lever and said leakport for controlling the escape of air from the leakport to vary the pressure in said output conduit in accordance with movement of said lever, a temperature sensing element having an actuating rod, a mounting plate for said element having a mounting wing flexibly connected thereto, means for mounting said wing in a plurality of interchangeable positions whereby the actuating rod may be made to engage on one side of the lever pivot or the other depending upon whether the instrument is to be direct acting or reverse acting, and a set point adjustment screw mounted on the control device in a position to engage with said mounting plate in either position thereof.

7. In a pneumatic control device having a pneumatic relay with a supply means for air and having an output pressure conduit leading from said relay, means connected with said relay and including a conduit having a leak-port, a pivoted input lever, means between said lever and leakport for controlling the escape of air therefrom to vary the pressure in said output conduit, temperature responsive means including an actuatin rod engageable with said input lever for causing pivotal movement thereof in accordance with temperature changes, a mounting plate for said element having a mounting wing flexibly connected thereto, means for mounting said wing in alternate positions whereby said actuating means may be made to engage on a selected side of the pivot for the input lever depending upon whether the instrument is to be direct acting or reverse acting, and a set point adjustment screw mounted on the control device in a position to engage with said mounting plate in either position thereof.

8. In a pneumatic control device having a pneumatic relay with a supply means for air and having an output pressure conduit leading from said relay, means connected with said relay and including a conduit having a leakport, a pivoted lever, means between said lever and said leakport for controlling the escape of air from the leakport to vary the pressure in said output conduit in accordance with movement of said lever, a temperature sensing element having an actuating rod, means for mounting said element in a plurality of interchangeable positions whereby the actuating rod may be made to engage on one side of the lever pivot or the other depending upon whether the instrument is to be direct acting or reverse acting, said mounting means providing for yielda-ble movement of the sensing element to vary its distance from said lever, and set point adjustment means on the control device having a screw intersecting the axis of the pivot of said lever and engageable with said mounting means for the senisng element to adjust the position thereof.

Hubbard et al Mar. 25, 1941 Scharpf June 26, 1951

Claims (1)

1. IN A PNEUMATIC CONTROL DEVICE HAVING A PNEUMATIC RELAY WITH A SUPPLY MEANS FOR AIR AND HAVING AN OUTPUT PRESSURE CONDUIT LEADING FROM SAID RELAY, MEANS CONNECTED WITH SAID RELAY AND INCLUDING A PIVOTED FEEDBACK LEVER AUTOMATICALLY PIVOTALLY MOVABLE IN RESPONSE TO FEEDBACK PRESSURE FROM SAID RELAY AND ALSO INCLUDING A CONDUIT HAVING A LEAKPORT ASSEMBLY WITH A MOVABLE LID FOR CONTROLLING THE ESCAPE OF AIR FROM SAID LEAKPORT TO VARY THE PRESSURE IN SAID OUTPUT LINE, A PIVOTED INPUT LEVER ENGAGEABLE WITH SAID LEAKPORT LID, TEMPEATURE RESPONSIVE MEANS FOR CAUSING PIVOTAL MOVEMENT OF SAID INPUT LEVER IN ACCORDANCE WITH TEMPERATURE CHANGES, AND MEANS MOVABLY MOUNTING SAID LEAKPORT ASSEMBLY INCLUDING ITS LID ON SAID AUTOMATICALLY PIVOTALLY MOVABLE FEEDBACK LEVER FOR SIMULTANEOUS ADJUSTABLE MOVEMENT RELATIVE TO SAID FEEDBACK AND INPUT LEVERS TO CHANGE THE DISTANCE FROM THE INPUT LEVER PIVOT TO THE POINT OF ENGAGEMENT OF THE INPUT LEVER WITH SAID LEAKPORT LID AND THEREBY VARY THE SENSITIVITY OF THE INSTRUMENT.

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