US2314211A - Condition responsive control - Google Patents

Description

2 Sheets-Sheet 1 n Inventor: George M. Hausler: by

Hrs Attorney March 16, 1943. c. M. HAusLER CONDITION RESPONSIVE CONTROL Filed Nov. 27, 1941 rig. 2.

Mardi 16, 1943- G. M. II-IAUSLER y 2,314,211

CONDITION RESPONSIVE CONT ROL Filed Nov. 2'?. V1941 2 suegra-sheet 2 Figi?.

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In ventor:

George M. Hauslem.

I' b5 `His ttor-neg Patented Mar. 16, A1943 UNITED sTATEs PATENT oEFiCE to General Electric Company,

New York a corporation of v Application November 27, 1941, Seria! No. 420,652

16 Claims. (Cl. 20G-140) The invention relates to condition responsive control, particularly to control devices such as t electric switches or the like operable with a diiferential in response to variations in a predetermined condition such as pressure, temperature or the like. y

One of the objects is to vprovide an improved multiple lever operating mechanism capable of more accurately amplifying relatively small but powerful movements of a condition responsive element to effect operation of a control device.

l Another object is to provide the improved operating mechanism with an improved multi-function compression biasing spring operating connection between the condition responsive operating element and the control device so as to bias all the parts of the improved multiple lever system into proper operating relation and thereby take up lost motion'therebetween as well as take care of overtravel in case the control condition should vary outside ythe normal operating range oi' the control device.

A still further object is to provide the improved operating mechanism with an improved multifulcrum differential lever mechanism whereby different values of the control condition required to operate the control device to each of two control positions may be controlled by independently ad- .iusting the fulcrums.

A more specific object is to provide an improved condition responsive operating mechanism of the above character in which the several operating parts are pivotally interconnected in cooperating relation as a unit with the unit pivotally suspended within a channel frame which also carries the improved form of condition calibrating scale as well as the control switch and the condition responsive operating element.

Other objects and advantages of the present invention will become evident from the following description of the accompanying drawings in which Fig. 1 is a mid-sectional view of a condi-- tion responsive control switch embodying the invention in a preferred form; Fig. 2 is a top view of the control switch shown in Fig. 1 withv the cover removed; Fig. 3 is Van end view of the control switch shown in Fig. 1 showing more clearly f switch.- Thelcover |2 has an opening I3 at one end forreceiving the upturned plate Il in which suitable knock-out openings I5 are provided for receiving the wiring connections of the external circuit to be controlled by the switch.

In the preferred form shown, the condition responsive element I8 is a bellows sealed within the casing I9 to which the bulb 2l is connected by the tube 2|, all of which are solidly iilled with an expansible liquid so as to produce contraction and expansion of the bellows I3 upon opposite variations of the temperature of the liquid in the bulb 20. The casing I9 is suitably secured to the base I3 so that the operating pin 22 extends upwardly from the bottom of the bellows I 8 through the opening 23 formed in the base I0 into operating engagement with the main operating lever 25. Other suitable forms of condition responsive elements may be employed for operating lever 25 if desired. Preferably, the upper end of pin 22 is suitably pointed so as to pivotally seat within. the depression 26 formed in the main lever arm 25 and thereby provide an anti-friction pivotal operating bearing therefor. The main lever arm 25 preferably is of channel shape to insure stiffness and is provided with a pair of slotted mounting ears 21 extending upwardly in spaced apart alignment from the channel sides adjacent one end thereof for receiving in the slots 28 thepin 23 which extends between the channel sides 30 of the auxiliary motion multiplying lever 3|. The auxiliary motion amplifying lever 3| preferably is formed of resilient material centrally stiil'ened by a channel shape, as shown, so that it may be pivotally mounted by riveting one end thereofto the downwardly projecting mounting finger 32formed at one end of the channel frame 33, within which all of the parts of the operating lever mechanism the details o: the calibrating scale mechanism;

A .lng scale; and Fig. 5 is a top view of the calibrat- 55 are enclosed. The pivotal movement of auxiliary lever 3| is limited by the spaced apart limit stops 34 and 35 which, as shown, are punched inwardly from the sides of the channel frame 33. If desired, the mounting nger 32 may be bent so as normally to bias the auxiliary lever 3| into ensagement with the lower stop 34, but this is not essential.

The channel frame 33 preferably is provided with suitable guide ears 33a at the four corners thereof which seat within suitable slots formed in the base l so as to properly position the channel frame on the base when the holding down screws 38, shown in Fig. 2, are tightened. The channel frame 33 is provided with suitable openings for receiving the anchoring bosses 31 of an enclosed snap action circuit controlling switch unit 38. In the preferred form illustrated, switch unit 38 is of the improved variable opposing bias snap action type more fullyv described and broadly claimed in the copending patent application Serial No. 403,474, flied July 22, 1941, and assigned to the assignee of the present invention, although other suitable forms of variable bias snap action switch units may be employed if desired.

Briefly, the improved form of switch unit 38 illustrated has a centrally pivoted contact operating lever 39 formed of magnetic material and variably biased into the position in which it is shown in engagement with the stop 40 by the permanent magnet 4| so as to carry the resiliently mounted movable switch contact 42 into engagement with the stationary switch contact 43. Operation of the movable switch contact 42 to the circuit opening position is effected through the agency of the opposing variable biasing spring strip 44, one end of which is flxedly mounted on the centrally pivoted lever 39 and the other end of which is engaged by the switch operating pin 45 that slides through a suitable guide opening formed in the mounting boss 31. The permanent magnet 4| serves to bias the movable switch contact 42 to the circuit closing position until the magnetic biasing force is overcome by the opposing spring biasing force set up in the spring 44 when the operating pin 45 The movable pointer 45 extends through slot 33a formed in the scale 33 and is flxedly secured to the large adjustment cam 53 which is rotatably mounted upon the rivet 31 extending from the bracket 52 and carrying the resilient washer 33 for holding the cam 63 and pointer 35 in the position to which they may be adjusted.

As shown more clearly in'Fig. 3, the adjustment cam 65 has its periphery in sliding seated engagement with the pin 1|) which is flxedly secured to and extends from the main operating lever 25 through the guide slot 1| formed in the bent over end 12 of the channel frame 33. Thus the adjustment cam 68 constitutes an adjustable fulcrum having sliding engagement with the pin 13 at the right-hand end of the main operating lever 25.

An improved multi-function biasing means, preferably in the form of a pair of compression springs 15, is interposed between the left-hand end of the main operating lever 25 and the auxiliary motion multiplying lever 3| so as to normally exert a force therebetween to bias the pin 28 into engagement with the upper end of the slots 29. These springs also bias arm 3| into engagement with stop 34, pin 10 into engagement with cam 86, and in addition provide an overtravel yielding connection between the levers 25 and 3| while transmitting the normal operating force and effectively preventing lost motion in the entire motion amplifying lever system.

. As a result, the improved form of motion multiis raised to effect operation of the centrally pivoted switch operating lever 39 out of engagement with the stop 40 and into engagement with the stop 48, thereby moving contact 42 to the circuit opening position. Due to the decrease in the magnetic biasing force occurring when the lever 39 moves away from the magnet 4|, the switch cannot be reclosed until the opposing biasing force of spring 44 is reduced b elow the decreased biasing force of magnet 4|.

In the improved differential operating mechanism of the present invention, the sliding movement of the switch operating pin 45 is controlled by the auxiliary differential regulating lever 50, which preferably is formed of resilient material so as to be pivotally mounted or hinged by securing one end thereof to the auxiliary motion multiplying lever 3| by the rivet 5|. The other end of lever engages with the adjustable stop 52 that is provided to vary the operating difierential in the manner described hereinafter. The adjustable stop 52 is carriedin the path of lever 50 at the end of the' spring strip 53 which is suitably secured to the channel frame 33 as by the rivets 54. The position of stop 52 in the path of lever 50 is adjusted by turning the screw 56 which is rotatably mounted in the top of the channel 33 and is in threaded engagement with the spring strip 53. 'I'he screw 5S is provided with a pointer 51 for operation over the differential calibration scale markings 58 provided on the top of the channel frame 33 between the limit stops 59, as shown in Fig. 2.

The main temperature Calibrating scale 89 is curved so as to be carried upon the bent over fingers 6| of the supporting bracket B2 which is secured to the channel frame 33 by the rivet 63.

plying lever mechanism of the present invention more accurately transmits small motions of the condition responsive element, and requires only one fixed pivotal connection to the channel frame 33; namely, the yielding hinge connection o; the auxiliary lever 3| to the bent over fingers 3 Operation Assuming the main calibration pointer 55 set at the particular temperature value of bulb 20 at which it is desired to open the control switch 38 and also the differential Calibrating screw set at the particular diiferential temperature value at which it is desired that the switch 38 be reclosed, the operation is as follows:

As the temperature to which the bulb 20 is subjected increases, expansion of the liquid enclosed within the sealed system causes the bellows I8 to contract and raise the pin 22 thereby rotating the main operating lever 25 about its sliding pivotal bearing with the adjustment cam 66. The amplified rotary movement of the left-hand end of lever 25 is transmitted through the compressed springs 15 to rotate the auxiliary motion multiplying lever 3| about its pivotal mounting on arm 32 while at the same time maintaining pin 29 in firm engagement with the upper end of. the slots 28, and pin 1U in firm engagement with cam 65. This further compresses springs 15 to some extent. As a result, any very slight but powerful movement of the bellows I8 is accurately amplified in the rotary movement of the right-hand end of auxiliary lever 3| with practically no. lost motion.

As the right-hand end of the auxiliary lever 3| is moved upwardly, the auxiliary differential control lever 50 remains in contact with the differential adjustment stop 52 until the projecting finger 3|a at the end of the lever 3| engages with lever 50. Thereafter, the auxiliary levers 3| and 50 both move as a unit to actuatethe operating pin 45 of the switch unit. When the switch operating pin 45 has been raised sumcientlyto build up suificient force in the variable biasing spring 44 to predominate over the magnetic force of magnet 4I on the switch operating lever 30, then the switch contact 42 will be operated with a snap action to the circuit opening position. 'nils willoccur with the bulb 2l at substantially the temperature value to which the adjustable calibrating pointer l5 is set when the operating mechanism is once properly calibrated.

In case the temperature to-which the bulb 2l is subjected should continue to increase after the opening of the switch, the bellows II will-continue to contract, thus stili further 'continuing the upward movement of 'the pin 22 and the rotation of the main operating lever 25. When auxiliary lever 3| engages with its upper limit stop 35, further upward movement of lever Il and switch operating pin 45 is 4impossible. Then the pair of springs 'I5 will be further compressed. and the slots 28 formed in the ears 2l will permit the continued upward movement of the lefthand end of the main lever 25 without introducing any abnormal strains in the lever system. Suitable openings Il are provided in the auxiliary lever Il for permitting the upturned ears 21 to pass therethrough in case of excessive overtravel.

When the temperature to which the bulb 2l is subjected decreases after the switch 3l has been opened in the manner described above, the bellows Il will be expanded to permit the downward biasing force exerted by springs on lever 25 to'move the pin 22 downwardly. This in turn will permit the biasing forces of springs 'l5 and spring 44 to lower the right-hand end of the motion multiplying lever 3l awayv from stop 35. However, the switch contact 42 will remain in the circuit opening position until the biasing force of the spring 44 has been reduced to a value below the reduced' magnetic biasing force tending to reclose the switch contact 42. Consequentover the temperature calibration scale 60 so as to vary the pointl of engagement of the cam with the pin 'Ill thereby. varying the temperature of the bulb 2l required to eifect operation of the switch to the circuit'opening position. The relatively small but powerful operating force of l the bellows Il is amplied with substantially no lost motion to eifect the opening movement of the switch due -to the improved operating connection provided by the biasing springs 15. The

sliding pivotal bearing between pin 'lll and the l calibrating cam 5 5 permits -any necessary slight endwise movement of the main operating lever 25 to occur. This is also true-of the pointed pivot pin operating connection .between the main operating lever :s and the bellows' pm zz. A11 of vlever 25 on the pointed end of the main adjusting screw 8l which extends through the channel frame 33 and is in threaded engagement with the arm 82 bent over from the end ly, the switch operating pin 45 must be vlowered of the channel I2. The adjusting screw 83 c'arriesa movable temperature calibrating scale which, as shown more clearly in Fig` 5, cooperates with the pointer 84 formedin the channel frame Il to indicate the temperature value at which the switch I5 is operated to the circuit opening position. A specially formed rotatable cam element 85 lrotates about the adjusting screw 8l as an axis as the cam 86 is of sufilcient thickness to rotatably engage'only with the ends of the threads formed on the screw Il and thus is not in threaded engagement therewith. The rotatable cam 8B is provided Wlthla spiral cam face 81 forengaging with the right-hand end 'of the auxiliary differential regulating lever 50 so as to vary the position at which the motion of the right-hand end of this lever is arrested in the switch closing operation. The rotatable cam B5 carries a pointer 88 extending upwardly throughthe slot 89 formed tial control stop 52, 'I'hereafter the right-hand l end of the diiferential lever 50 will pivot about stop 52 while the left-hand end of lever 50 continues to be lowered due to the continued lowering movement of the lever 3 I. y When the bulb 20 reaches the predetermined differential temperature value corresponding to the adjustment of the screw 56, switch operating pin 45 will be lowered sulciently so that the reduced magnetic biasing force of magnet 4l will again predominate overthe variable spring biasing force of spring, and the switch contact 42 will be returned to the circuit closing position with a snap action.' The differential adjustment screw 5i, being normally stationary, may bereadily adjusted at any time Without interfering with the operation of the movable parts oi the device.. AIn this respect, the present invention provides further improvements upon the improved diiferential adjustment invention disclosed and claimed in the patent application Serial No. 403,474 noted above.

With the improved operating mechanism of the present invention, the pointer 85 may be adjusted in the channel frame 33 into cooperating relation with the movable scale l! carried by the adjusting screw 80, as clearly shown in Fig. 5. The spring serves to hold the rotatable cam 56 in frictional engagement with the arm 82 in the particular position to which it may be adjusted.

The operation of the switch 38 by the bellows l. inresponse to variations inthe temperature With the improved Calibrating mechanism shown in Figs. 4 and'5, both of these temperature values may be indicated. directly upon the moving scale 83. In this respect, my present lnvention provides further improvements in the improved differential calibrating mechanism described and claimed in my patent application Serial No. 412,415, filed Sept. 26, 1941.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. In combination, a control member movable between two control positions, opposing biasing means therefor having a reversible predominance, a main operating lever having lost motion pivotal connecting means adjacent one end thereof, an adjustable fulcrum for engaging the other end of said main lever, condition responsive means having an operating member engaging said main lever between the. ends thereof, an amplifying lever overlapping the said one end of said main lever and interconnected with said lost motion pivotal connecting means, means for rotatably supporting one end of said amplifying lever, a compression spring interposed between said amplifying lever and the said one end of said main lever to take up the lost motion in said pivotal connecting means and bias said levers to rotate in opposite directions about said pivotal connecting means and thereby provide both a yielding and a biasing operating connection therebetween, a differential control lever hinged adjacent the other end of said amplifying lever to be moved as a unit therewith to render one of said biasing means predominant over the other to bias said control member to move from one of said positions to the other and to be moved relatively to said amplifying lever to render the other of said biasing means predominant over said one biasing means to bias said control member to return from said other position to said one position, and an adjustable stop disposed in the path of said differential control lever to regulate the said relative movement thereof. v

2. In combination, a movable control member, a main operating lever therefor provided with a pair of slotted ears in spaced apart lateral alignment adjacent one end thereof, an adjustable fulcrum for engaging the other end of said main lever, condition responsive means having an operating member engaging said main lever between the ends thereof, an amplifying lever overlapping the said one end of said main lever and having a connecting pin extending through said slotted ears, a differential control lever hinged adjacent one end of said amplifying lever to be moved as a unit therewith to move said control member from one position to another position and-to be moved relatively to said amplifying lever to move said control member from said other position to Ysaid one position. means for rotatably supporting said amplifying lever, a compression spring interposed between the said one end of said main lever and said amplifying lever to provide a yielding operating connection therebetween, and an adjustable fulcrum for said differential control lever to regulate the said relative movement thereof.

3. In combination, a movable control member, opposing biasingmeans therefor, condition return from said other position to said one position,andanadjustablestopdispodinthepath of said differential control member to regulate the said relative movement thereof.

4. In combination, a control member movable between two control positions, opposing variable biasing means therefor, one variable into predominance over the other to bias said Y control member to move from one of said positions to the other and out of predominance over the other to bias said member to return to said one position, and condition responsive means having a multiple lever mechanism operatedl thereby for varying said one biasing means and provided with lone adjustable fulcrum for controlling the operation thereof to vary said one biasing means into predominance over the other and a second adjustable fulcrum for controlling operation thereof to vary said one biasing means out of predominance over the other.

5. In combination, a lever pivotally supported at one end and having a pair of levers pivotally connected thereto, a pair of separately adjustable fulcrums, each disposed in the path of a corresponding one of said pair of levers, condition responsive means for moving one of said pair of levers to effect movements of said first vcondition responsive means and provided with an adjustable fulcrum and another lever connected to be operated by said one lever and provided with a separately adjustable fulcrum, and control means having a member operated by said other lever to one controlling position upon variation of said condition to a value determined by the adjustment of one of said fulcrums and to another control position upon variation of said condition to a value determined by the adjustment of both of said fulcrums.

7. In combination, a control device. a condition responsive multi-lever operating mechanism for said device including a lever pivotally supported at one end and having a second lever hinged adjacent the free end thereof for movement as a unit therewith for operating said control device and l.V third lever provided with a lost motion pivotal connection intermediate the ends of said first lever. condition responsive means for operating said third lever, an adjustable fulcrmn at the other end of said third lever for calibrating said mechanism, and an adjustable fulcrum disposed in the path of said second lever for regulating the operating differential of said mechanism.

control member to move from. one control position to another and to have relative movement v with respect to said lever to render the other of said biasing means predominant over said one biasing means 'to bias said control member to 76 8. In combination, a first lever having an operating member hinged thereto, a control device operated by said member. a second lever having a lost motion yielding connection for op- 9. In combination, a condition responsive element, a floating lever having an operating connection with said element and provided with a pair of slotted ears in spaced apart lateral alignment adjacent one end thereof and a longitudinal pin extending from the other end thereof, control means having a movable operating member provided with a connecting pin extending through said slotted ears, a compression spring interposed between said movable operating member and the'said one end of said lever to provide a one-way biased operating connection therebetween, means providing a slotted guide for said longitudinal pin, and an adjustable fulcrum for varying the position of said pin in said slotted guide for controlling the movement vof said operating member.

10. In combination, a control device having a control member eiiective upon movement thereof to each of two control positions and ineffective during movement intermediate said positions, a condition responsive device having an operating lmember movable in accordance with variations in a predetermined condition, means for. oper-' atively vinterconnecting said Vmembers including a supporting lever connected to be operated by said operating member, a` multi-fulcrum lever having a fulcrum for abutment with one end thereof and a restricted hinge connecting the other end thereof 'with saidA supporting'lever to eiect pivotal movement of said multi-fulcrum lever away from said abutting fulcrum about the fulcrum of said supporting lever to operate said control member between an intermediate position and one of said control positions and to effect a pivotal movement of said multi-fulcrum lever about said abutting fulcrum to operate said vcontrol member between said intermediate position and the other of said control positions,

to Vary the operating differential of saidcon trol member. 11. In combination, a control device lhaving a control member eectiv'e upon movement thereof to each of two control positions and ineffective during movement intermediate said positions, a condition responsive device vhaving an operating member movable in accordancewith variations in a predetermined condition, means for oper-` meansfor adjusting one of said fulcrums to vary the operating differential of said control member.

12. `In combination, control means, condition responsive means having a multi-fulcrum lever mechanism for operating said control means, and

Ameans for adjusting said mechanism including' an adjusting screw for controlling one fulcrum of said mechanism and having a rotatable calibrating scale element and a separately adjustvmulti-fulcrum lever mechanism for reversing the predominance of said biasing means to eifect operation of said control member between said control positions, and means for adjusting said mechanism including a pair of separately adjustable members having interdependent calibrating elements and each controlling a fulcrum o' said mechanism.

14. In combination, a control member movable between two control positions, condition responsive means having a multi-fulcrum lever mechanism for operating said member, and means for adjusting said mechanism including a pair of separately adjustable rotatable members having interdependent Calibrating elements and each controlling a 'fulcrum of said mechanism.

15. In combination, control means, condition responsive means having a multi-fulcrum lever mechanism for operating said control means, and' means for adjusting said mechanism including a pair of separately adjustable, concentric, rotatl operating element, a floating lever provided with by said operating member for moving said lever about one fulcrum to effect operation of said control member between an intermediate position and one of said control positions and about another fulcrum to eiIect operation of said control member between said intermediate position and the other of said control positions, and

a lost motion coupling element at one end thereof anda sliding guide element at the other end thereof and having an intermediate operating connection with said operating element, a control device having va' movable operating member provided with a coupling element and a. biasing element for cooperating with said lost motion vcoupling element to provide a. one-way `:yielding overtravel operating connectionl between said oating lever and said operating member. and an adjustable stop in sliding engagement with said sliding guide element for providing 'a fulcrum for said'lever. I

anonce u. Estrema.

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