US2396541A

US2396541A - Heat motor operated mechanism

Info

Publication number: US2396541A
Application number: US432448A
Authority: US
Inventors: Daniel G Taylor
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1942-02-26
Filing date: 1942-02-26
Publication date: 1946-03-12
Anticipated expiration: 1963-03-12

Description

March 12, 1946. D. G. TAYLOR 2,396,541

HEAT MOTOR OPERATED MECHANI SM Filed Feb. 26, 1942 2 Sheets-Sheet 1 L V INVENTOR. @aniel Taylor Afim'ner March 12, 1946. D. e TAYLOR 2,396,541

HEAT MOTOR OPERATED MECHANISM Filed Feb. 26, 1942 2 Sheets-Sheet 2 j 53 ig.

' attorney Patented Mar. 12, 1946 HEAT MOTOR OPERATED MECHANISM Daniel G. Taylor, Minneapolis, Minn, asslgnor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application February 26, 1942, Serial No. 432,448

13 Claims.

This invention is directed broadly to devices which are operated by means of a heat motor, and is more particularly concerned with a heat motor and associated mechanism for operating a pilot valve for controlling a diaphragm pressure operated valve.

It is old in prior art devices, such as shown and claimed in my ccpending application Serial No. 390,553, filed April 26, 1941, now Patent Number 2,349,209, granted May 16, 1944, and entitled Control device." to control a diaphragm valve such as a diaphragm gas valve by means of a pilot valve mechanism which is in turn under the control of an electromagnet. Devices of this type are entirely satisfactory when they are so positioned that the noise in the magnet when it is energized as well as the noise made by the magnet as it pulls in and drops out, is not objectionable. In some installations however, it is important that the operation of the mechanism be absolutely silent, and it is therefore a prime ob- Ject of the present invention to design an operating mechanism for a pilot valve which will be exceedingly quite in its operation.

An additional object. of the invention is to pro-' vide a diaphragm valve in which a pilot valve mechanism for operating it and the heat motor for the pilot valve mechanism are mounted directly upon the valve body. An additional object of the invention is to provide such a combination with a manual means for operating the pilot valve in the event that the electric power supply for the heat motor should fail.

A further object of the invention is to operate a control device by means of a heat motor and to provide aslip friction connecting means between them to provide for overrun of the heat motor after the control device has been actuated and to provide for an immediate operation of the control device upon a reversal in the movement of the heat motor.

An additional object of the invention is to operate two control devices by means of the heat motor and to provide a slip friction connection between the heat motor and each of the control devices so that each may be operated independently by the heat motor and the slip friction connections will provide for overrun of the mtor after the devices have been actuated.

A further object of the invention is to heat the heat motor by means ofan electric circuit and to connect the heat motor with a valve. The circuit in this case is controlled by a condition reresponsive device which actuates two switches then closes a third switch to provide a holding circuit for itself through the first to close switch of the condition responsive device. Both the control valve and the third switch are connected to the heat motor by means of slip friction connecting means.

It is a still further object of the invention to utilize a heat moto of the hot wire type and to provide some means for returning the control device actuated by the heat motor to a safe position in the event that the hot wire should break.

In one form of the invention it is contemplated that the hot wire shall be wound around teeth on a fixed member and a movable member and that the movable member should actuate the control device. In thi form of the invention the wire used is so still that it will not slip with respect to the teeth in the event that the Wire should break so that under these circumstances the resultant contraction of the wire upon cooling would return the control device to its safe position. In another form of the invention the movable member which is actuated by means of the hot wire heat motor, is biased by means of a spring for rotation in a direction to place the wire under tension. The spring is connected to the movable member by means of a releaseable connection so that if the movable member should arm which is in turn actuated by the movable member. In this case. when the movable member moves excessively, indicating that the hot wire has broken, the actuating arm engages a fixed abutment which causes it to rotate in the opposite direction and return the control device to a safe position.

These and other cbiects of the invention will readily become apparent to those who are skilled in the art as the following specification is read in the light of the accompanying drawings, in

which a Figure 1 is a plan view of a device embodying the various features of my invention, a portion of the circuit connections being shown diagrammatically,

Figure 2 is a side elevation of the embodiment shown in Figure 1,

in succession for energizing the heat motor which v Figure 3 is a detail view of the slip friction connections, partly in section, the section being takenalongthelineHofFigurel,

Figure 4 is a detail view oizthe manual reset mechanism with its strain release feature, with a portionshown in section, the section being taken along the line 4-4 of Figure 3,

Figure 5 is a detail view showing a modified form of my invention for causing a safe movement of the valve mechanism in the event of a breakage in the hot wire.

Figure 6 is a slightly enlarged view of 'the structure shown in Figure l, superposed portions thereof being omitted or broken away, and

Figure 'l is a slightly enlarged end view of the upper portion of the structure shown in Figure 1.

Referring now to the drawings, the reference numeral ill indicates a valve casing which has a diaphragm valve indicated -by dotted lines at H in Figure 2. A pilot valve device is mounted on top of the valve casing as indicated at l2 and is adapted to control the pressure on top of the diaphragm and therefore control the operation of the diaphragm valve. This much of the construction forms no part of the present invention and is in fact, shown in my copending application, Serial No. 390,553, filed April 26, 1941, now Patent Number 2,349,209 granted May 16, 1944, and entitled Control device.

The'pilot valve mechanism l2 comprises a supply'valve and a waste valve which are operated by means of a lever i3 pivotally mounted as shown at It and adjustably carrying the two screws i5 and it. The screw I5 is adapted to open the waste valve as the lever i3 is rotated n a counter clockwise direction as seen in Figure 1 for venting the chamber above the diaphragm and permitting the diaphragm valve to move to open position. The screw I3 is adapted to open the supply valve as the lever I3 is rotated in a clockwise direction admitting pressure to the diaphragm chamber for closing the diaphragm valve. The details of construction of this pilot valve mechanism are fully disclosed in the aforementioned application, Serial No. 390,553, and form no part of the present invention. Each end of the lever I3 is bent inwardly to form a pair of stops i'l to prevent the lever l3 from having any excess rotation after the supply or waste valve has been :tuated. The reason for this will appear later.

The lever I3 is provided with an extension l3 which carries a downwardly extending pin I! which is in turn received by the slot 23 in the right hand end of a fioatingly mounted operating arm 2|. The arm 2| is carried by means of a slip friction connecting means by the extension 3| theeonicalmemberitiscausedtopressthe extension 22 and lever 2| together against the graphite washer 23 thereby providing a slip friction connection between the extension 22 and the lever 2 l.

The pivoted bracket 23 carries a plate 32 iomd of some insulating material such as Bakelite. This plate is provided with a plurality of teeth 33. A second insulating Plate 33 is suitably fixed to member 33 carried by the plate 23. Th insulating plate 34 is also provided with a pinrality of .teeth 33. One end of a thin metal wire is securely wrapped around a screw 31 which is fixed to the insulating plate 34., This wire is then wrapped around alternate teeth on the two

insulating plates

32 and 34 to form a plurality of strands of a hot wire thermal member 33. The other end of the wire is then brought back against the insulating plate 34 and is securely fastened to a second screw located below the screw 31. This wire is chosen so as to have suiiicient resistance so that when an electric current is passed through it, it will heat up appreciably and expand. The pivoted bracket 23 is provided with a finger 33 over which is hooked one end of a tension spring 33, the other end being hooked to an extension 21 on the fixed member 38. The effect of this spring is to tend to rotate the pivoted bracket 23 in a clockwise direction and therefore maintain the strands of wire under tension. It will thus be seen that as the wire 38 is heated up the strands will expand and permit the bracket 23 to rotate in a clockwise direction under the influence of the spring 39, but as these strands contract they will rotate this bracket in a counter-clockwise direction.

As the bracket 23 rotates in a clockwise direction the extension 22 will carry the floating lever 2| with it and cause it to rotate lever l3 in a counter-clockwise direction whereupon the screw II will open. the waste valve and permit the dia- 22 on the pivoted bracket 23 which is pivotally mounted as shown at 24 on a plate 25 which is in turn supported by posts 23 on the valve casing l3. Referring to Figures 3 and 6 the slip friction mechanism comprises a graphite washer 23 which is located between the lever 2| and the extension 22 on th bracket 23. The washer 23 is suitably carried by means of the lever 2|. The conical member 23 has a small stem which extends through an opening in the extension 22 and also through the washer 23. A bronze spring 33 is anchored at one end in the lever 2| and at its opposite end it engages the point of the conical member 2!. The spring 33 a portion of which is broken away in Figure 6 to more clearly show the underlying structure, is tensioned downwardly by means of the screw 3| which enters a tapped hole in the lever, 2|. By tightening the screw phragm valve to open. It will be noted that the lever I3 has only a slight rotative movement after which one or the other of the inturned ends i1 will engage the pilot valve housing l2 and prevent further rotation. Further rotation of the bracket 23 will then be permitted due to the slip friction connection between the extension 22 and the floating lever 2|. Therefore, as soon as the direction of the rotation of the bracket 23 is reversed the lever l3 will immediately start to move and actuate the pilot valve mechanism. Then after further movement of the lever I3 is prevented, the slip friction mechanism between the extension 22 and the floating lever 2| will again function to permit further movement of the bracket 23. Thus, it will be seen that the slip friction mechanism provides for actuation of the pilot valve mechanism just as soon as the bracket 23 reverses in its movement and that this slip friction mechanism will then provide for an overrun movement of the bracket 23. It will be understood, of course, that when the bracket 23.

rotates in a counter-clockwise direction that it will carry the floating lever 2| with it and cause the lever |3 to rotate in a clockwise direction whereupon the screw it will permit closure of the waste valve and the screw it will open the supply valve to close the diaphragm valve,

The pilot valve device I2 is one of two control devices operated by the hot wire thermal member 33. The other control device is a switch which will now be described.

A suitable insulating block 43 is mounted on 43 to a bracket 44 which is in turn, suitably carried by the insulating block 48. A. stationary contact 45 isalso carried by the insulating block 49 and so positioned as is best shown in Figures 1 and 6, as to cooperate with the movable contact arm 42. The engagement of the movable contact arm 42 with the stationary contact member 45 limits the rotation of the arm 42 in one direction whereas the adjustable screw 45 which is carried by the bracket 44 limits the rotation of this contact arm 42 in the opposite direction. The contact arm 42 is provided with an extension 41 which carries a pin 48 extending downwardly into a slot into the insulating member 48. A portionof the extension 41 is broken away in Figure 6 to more clearly show the slotted insulating member 49. This member 49 is carried by the bracket 23'by means of a,slip friction connection.

Referring particularly to Figure 3, it will be seen that this slip friction connection comprises a metal cup 50 which is carried by the bracket 23 andwhich in turn carries a graphite washer bronze plate 52 which engages the surface of the friction washer 5|. A conical member 53 is pro- I .vided with a stem, not shown, which" extends downwardly through the member 49 and through the graphite washer 5|. This conical member 53 The insulating member 49 carries a small -A movable contact arm 42 is pivoted as shown at 7 tration, this device is shown as comprising a thermostat 88 which is formed by a-bimetal memblade II will first engage the contact 81 and then at a slightly lower temperature the contact blade 12 will engage the contact 8|. The bimetallic member 13 is connected to the stationary contact member by. means of conductor 13.

. The operation of the device as far as it has been described, should now be apparent. When the thermostat 89 is satisfied, the bimetallic member 10 will maintain the two contact blades II and 12 in open circuit position. Under these circumstances, the circuit to the hot wire thermal member 38 will be broken and this member will therefore be cold in its contracted position. It will therefore have rotated the bracket 23 to its counter-clockwise position and this bracket will have moved the floating lever 2! to a position where it has caused the screw 18 to open the supply valve to bleed pressure into the diaphragm chamber and therefore close the main diaphragm valve. On a decrease in temperature at the thermostat 89 the bime'tal member l9will contract and cause the contact blade 'H to engage the stationary contact 81. This operation will not result in an establishment of any circuit due to the fact that the bracket 23 in its counter-clockwise position is forced downwardly by means of the bronze spring 54 which is anchored in one end in the bracket 23 and which bears at its other end against the conical member 53. The force with which this member bears against the conical member 53 is determined by means of the screw 65 which engages the bronze spring 54 and which is screw-threadedly received in the bracket 23. In this case, the friction is between the graphite washer 5| and the bronze plate 52. It will be understood, of course, that by tightening the screw '55 the pressure is increased betweenthe bronze plate 52 and the graphite washer 5i and therefore, the amount of the friction is increased.

Y will again be permitted by the slip friction connection. Thus, it will be seen that the switch 42, 451s always actuated immediately upon a reversal of movement of the bracket 23.

One end of the wire forming the hot wire thermal member 38 is connected to a terminal screw 58 on the bracket 44 by means of the conductor 59. The bracket 44 is connected by means of the conductor 88 to a stationary contact 3|. The other end of the wire 38 is connected by means of conductor 82 to the secondary winding 63 of a step-down transformer 64 which has a primary winding 35. The primary winding 85 is,

of course, adapted to be connected to a suitable source of power. Conductor 68 connects the other side of the secondary winding 83 to asecond stationary contact 81. The circuit across the two stationary contacts GI and 81 may be controlled by any suitable device. For the purposes of illusmaintains the contact blade 42 in open circuit position. Therefore, the temperature will continue to decrease until the contact blade 12 is brought int engagement with the stationary contact 6|. This will establish a circuit from one side of the secondary winding 83 through conductor 68, contact 61, contact blades H and 12, contact 6|,conductor 80, bracket 44, terminal screw 58, conductor 59, hot wire 38, and conductor 82 back to the other side of secondary winding 33. This will result in a flow of current through the hot wire thermal member 38 which will then increase in temperature and expand permitting the biasing spring 39 to rotate the bracket 23 in a. clockwise direction. This bracket 23 will then.carry the floating lever 2| downwardly as seen in Fig. 1, thus causing the screw l8 to permit the supply valve to close and causing the screw l5 to open the waste valve. This will bleed the diaphragm chamber and permit the main diaphragm valve to open. Rotation of the bracket 23 in a clockwise direction also causes a counter-clockwise rotation of the contact arm 42 which will result in its being brought into engagement with the stationary contact member 45. This sets up a holding circuit from one side of the secondary winding 63 through conductor 66, contact 61, contact blade ll, bimetallic element 10, conductor 13, stationary contact member 45, contact arm 42, bracket, terminal screw 58. conductor 59, wire 38 and conductor 62 back to the other side of secondary winding 63. It w ll thus be apparent that the circuit through the hot wire 38 will remain closed until the temperature rises 'suiliciently to cause the bimetallic element 18 to separate the contact blade II from its stationary contact 81. When this action takes place the circuit to the hot wire element will be broken and it will therefore cool and contract causing a countar-clockwise rotation of the bracket 23 and a resultant movement of the floating lever -2l back to its original position in which it permits the screw I5 to close the waste valve and causes the screw l8 to open the supply valve, thereby bleed- Asstated above, both the contact arm I! and r the pilot valve actuating lever II have relatively limited movement and the two slip friction mechanismsbetweenthemandthebracketlt permit overrun movement of the bracket 28. vItwill also beapparentthatbothofthesewill beactuatedassoonasthereisareversalofmov ment of the bracket 28. This provides fora positive operation of these mechanisms substantially immediately uponthe opening or closing of the circuit through the hot wire thermal element 38.

InvaJvesofthisWJtisdesIrabIetopmvidesome means for manually operating the pilot valve mechanism in-the event that the electrical power for operating this mechanism should fail for some reason. Thus, a means has been shown in the form of the lever it which is pivotally mounted upon a bracket 8| suitably fixed to the valve casing II. This member is provided with what is known as a scissors-type strain release formed by a pair of levers 82 and I! mounted concentrically with the lever II. A biasing spring 84, connected between one end of these levers. biasesthemagainstastopllmountedonthe lever II.

The left hand end of the floating lever Ii is provided with a downwardly extending portion 86 which extends between the two ends of the levers I! and I8 opposite the biasing spring n. Thus, a rotation of the lever il in either direction will cause one or the other of the two levers t2 and It to engage the projection It and cause rotation of the lever II and a consequent actuation of the pilot valve mechanism. After the lever 2| has been stopped from further rotation by the pilot valve mechanism, further movement of the lever II will be permitted by the elongation of the spring ll. In other words, the lever Ii is driven by the lever OI through the spring 84 which acts as a strain release when flu'ther movement of the lever ii is not permitted.

It will be noted also that the manual lever ll acts directly upon the lever 2i and that movement of this lever is permitted with respect to the bracket 23 by means of the slip friction connection between the two. Thus, manual actuation of the pilot valve mechanism does not affect the thermal member 38 nor does it place any strain whatever thereon. v s

It would be dangerous if it were possible for the breakage of the wire of the hot wire thermal member ll, due to burning out or for some other reason, to permit the pilot valve mechanism to remain in a position indefinitely to cause the main diaphragm valve to remain open. It is necessary, therefore, to provide some means for returning this pilot valve mechanism to a safe position in the event of such breakage. There are several ways in which this could be done. In the first place, the wire for the hot wire thermal member 38 could be chosen to be relatively still. so that when it was wound around the teeth 33 and it as shown in Figure 2, it would not slip with respect thereto upon breakage of the wire. Thus, ifthewireweretobreakatonepointthecircmt aaoaur 7 88 will come into play bracket II to its counter-clockwise posi so hence, move the pilot valve mechanism to its safe position. This spring ll, of course, would have thermal member 38. a mid-portion of the fioating lever 2|. would engage the pin ll so that as the left hand end of this leverwas carried downwardly due to clockwise rotati a the lever 2| would rotate about the pin II to cause a clockwise rotation of the lever it and therefore, a movement of the pilot valve mechanism to a safe position.

It will be noted that the entire mechanism with the exception of the condition responsive device is relatively small and compact and it is mounted directlyuponthevalvebody,andbeingoithe heat motor type, would be extremely silent in operation. It will be further noted that this mechanism provides for manual operation in the event of power failure and provides for the movement of the pilot valve mechanism to a safe position intheeventthatthehotwireof thethermal motor should burn out.

As various changes and modifications of invention will undoubtedly occur to those who are skilledinthearhldesireittobeunderstood thatlintendtobelimitedonlybythescope oi the appended claims and not by the specific embodiments which have been shown merely for the purposes of illustration.

I claim as my invention:

l.lnadeviceofthecharacterdescribed.in combination. a movably mounted control device. stop means for determining two positions of operation of said control device, a heat motor including a thermally responsive member adapted to be connected to a power supply. an operator for said control device, connections between said heat motor and operator whereby said heat motor operates said control device, said connections including two elements connected by a slip friction connection so as to provide for overrun of the heat motor after said control device has been moved to one of its positions. and manual means associated with said operator for moving said control device in the event of a failure in the power supplyforsaidheatmotonsaidmanualmeaus control device, slip ei'rictlon means connecting I comprising a manually movable member so connected to said operator that movement oi. said manually movable member causes movement of said control device without ail'ecting the position of said heat motor.

2. In a device of the character described, in

- combination, a movably mounted control device.

stop means for determining two positions of operation of said control device, a heat motor including a thermally responsive member adapted to be connected to a power supply, an operator for said control device, connections between said heat motor and operator whereby said thermally responsive member operates said control device, said connections including two elements connected by a slip friction connection so as to provide for overrun of the heat motor after said control device has been moved to one of its positions, manual means associated with said operator for moving said control device in the event of a failure inthe power supply for said heat motor, said manual means comprising a manually movable member connected to said operator for movement thereof without causing movement of said heat motor, and strain relief means associated with said manual means for limiting the amount of force which can be transmitted to said control device.

3. In a device of the character described, in combination, a movable member biased for movement from a first to a second position, means including a thermal element of the hot wire type restraining said member from such movement and holding it in said first position when said thermal element is cold, a control device having corresponding first and second positions of operation, operative connections between said movable member and said control device, said movable member moving said control device from first to second operative position as a result of its bias upon heating and expansion of said hot wire thermal element, and means for moving said control device from second to first position in the event of the breakage of the wire of said hot wire thermal element and independently of the cooling and contracting urge of said broken thermal element.

4. In a device of the character described, in combination, a movable member biased for movement in a direction from a first to a second position, means including a thermal element of the hot wire type restraining said member from such movement and holding it in said first position when said thermal element is cold, a control device having corresponding first and second positions of operation. operative connections between said movable member and said control device, said movable member moving said control device from said first to said second operative position as a result of its bias upon heating and expansion of said hot wire thermal element, said operative connections including an arm rotatably connected to said movable member, means resisting relative rotations betweensaid member and arm, and means engaged by said arm for causing such relative rotation to move said control device from said second to said first position in the event of breakage of the wire of said hot wire thermal element.

5. In a device of the character described, in combination, a movable member biased for movement in one direction, means including a thermal element of the hot wire type restraining said member from such movement and holding it in a first position when said thermal element is cold, a control device having two positions of operation, an arm operatively connected to said said arm to said movable member whereby said control device may be operated from one operative position to another by said movable member upon expansion of the hot wire of said thermal element, and stationary means engaged by said arm to cause reverse movement thereof and movement 01' said control device back to its said one operative position in the event that said movable member moves excessively due to breakage of the hot wire of said thermal element.

6. In a device of the character described, in

combination, a control device movable between a safe position and an active position, said device being biased to said active position, means including a thermal element of the hot wire type connected by a lever to said device for restrain ing said device and holding it in said safe position when saidthermal element is cold and for expanding when hot to permit said control device to be moved to said active position, and a stop in the path of said connecting lever and effective in the event of excessive movement of said lever as a result of the breakage of said hot wire thermal element to change the character of said movement so as to cause said control device to be moved to said safe position.

7. In a device of the character described, in combination, a control device movable between a safe position and an active position, said device 'cluding an electrically energized thermal actuated element of the hotwire type for restraining said device and holding it in said safe position when said thermal actuated element is cold and for expanding when hot to permit said control device to be moved to said active position. said thermal element comprising a plurality of substantially parallel loops, and means eiiective in the event of the breakage of any loop of said hot wire thermal actuated element to permit movement or said control device to said safe position without causing corresponding movement of said thermal actuated member.

8. In a device of the character described, in combination, a movably mounted member, a biasing spring therefor, means connecting said spring to said member for biasing it for movement in one direction, means including a thermal element of the hot wire type restraining said member from such movement and holding said member in a first position when said thermal element is cold, a control device having first and second positions of operation, operative connections between said movable member and said control device, said movable member moving said control device from first operative position to second operative position as a result of its bias upon heating and expansion of said hot wire thermal element, said movably mounted member and said thermal element being constructed and arranged to permit the return movement of said movable member to its first position upon breakage of said hot wire thermal element and independently oi the cooling and contracting urge and movement of said broken thermal element.

9. In a control device, a heat motor operably associated with said control device, means for supplying power for said heat motor, slip friction connecting means between said heat motor and said control device whereby the latter is operated by the former, said connecting means being disposed to transmit movement in alternate directions to the control device concurrently with the initiation of similar movement or said heat motor,

6 w aseasu mean'spermit iingmovementot oontmldeviceinaelosinadireetionand inopeningdirectiimbtsaidheatmutorlntheevento breakage oi'saidmotonandmannalmeansior operatingsaidcontroldevleeintbeeventthat thepowertosaidheatmotorshouldtaihsaid manual means a manual operator valve means, said heat motor comprising one!- pansible wire, electrical means for heatins said expansibie'wire. a nmed member having a pinraliivoi'teetmoneendoisaidwirebeingiastened to. the said fixed member, a rotatable memberhavingapluralitvotteethsaidwirebeing passed-around said teeth alternatelyonsaidrotatable member and said fixed member to iorm a plurality of substantially parallel strands. the otberendotsaidwirebeingiastenedtossidflxed member, meansbiasingsaid rotatable memberfor rotation in a direction to tension said strands whereby said member will rotate in'that directionwhensaidwireisexpandedbyaeot vcurrent therethrough, a triction connection betweensaidrotatablememberandsaidpilot valve means so tbat'said pilot valve means is aaidcmtroldevicoqithoutlimitlngthemove- .mentorsaidthermalaehiated eiementand quicklymoveduponaehangeintheconditionoi" energiaation of said wire,am l stop means operable under certain conditions to reverse the movement of said pilot valve while permitting forward movement of said rotating member.

11.Inadeviceottheeharaeterdescrlbed.in combination, a control device movable between a safe position and an active position, said device beingbiasedtosaid active position means ineludinzathermalactuatedelementoithehot -wirewpetorsaiddeviceandholdins itinsai'e position whensaidthermalaetuated elementiscoldandiorexpandingwhenhotto permitsaidcontroldevicetobemovedtosaidfl active position. means limiting the movement of DAM! G. TAYIDR.