US2144587A - Control mechanism - Google Patents

Description

Jan. 17, 1939. C G KRONMlLLER 2,144,587

CONTROL MECHANISM Filed Nov. 5, 1954 2 Sheets-Sheet 1 nvvav roe Carl 6. Jfronm file] Jan; 17, 1939. c, G, KRONMILLER 2,144,587

CONTROL MECHANI SM Filed Nov. 3, 1954 2 Sheets-Sheet 2 m/ VE/VZ'OE (3a)"! Gjfranmi/Zer Patented Jam 17, 1939 UNETED STATES PATENT OFFICE CONTROL MECHANISM aware Application November 3, 1934, Serial No. 751,429

18 Claims.

This invention relates to control mechanisms in general, and more specifically to a combined liquid level and pressure control mechanism for switches, and is of particular utility in operating mercury switches.

An object of this invention is to provide a novel combined pressure and liquid level control mechanism for operating a switching mechanism which is independently responsive to changes in pressure and to changes in liquid level.

Another object is toprovide a control mechanism of the class described embodying a lost motion connection so that surges in the float chamher are not transmitted to the control device or switch.

A further object is to provide a control mechanism for operating a switch or like mechanism which opens the switch when a predetermined high pressure or a predetermined low liquid level occurs, with means for latching the switch in open position requiring manual re-setting of the mechanism for further operation.

A still further object is to provide a control mechanism that is operated by independent means responsive to changes in different conditions, one of said means embodying a lost motion connection, and the other means embodying a strain release connection.

Another object is to provide a latching mechanism of novel character whereby a member movable to inoperative positions by changes in separate conditions may be latched in inoperative position when so moved by one of said conditions.

A further object is to provide a control mecha- "nism of the class described'having a member to mechanism with certain parts being shown in ele-' vation;

Fig. 2 is a partial front elevational view looking from the left in Fig. l with the cover removed, parts shown in section, and the mercury tube switch shown in broken lines for clearness;

Fig. 3 is an exploded perspective view of the elements forming a part of the control mecha-- nism; and

Figs. 4, 5, and 6 are partial elevational views showing a portion of the control mechanism in various major positions.

Although the control mechanism of this invention is capable of use in different types of systems, it is preferably shown and described as a combined pressure and liquid level control mechanism wherein l0 designates generally a housing or float chamber which consists of a front portion II and a rear portion l2 having a gasket I3 interposed therebetween, these portions being secured together by nut and bolt arrangements M. The front portion H of the float chamber I0 has an upper opening I5 and a lower opening I 6, which openings receive pipe connections to be attached to a device whose liquid level is to control the instrument. Such connections, for example, may be made to the ends of a gauge glass of a boiler so that the water level of the boiler would be transmitted into the casing or float chamber III. Since the float chamber I0 is connected to a device having a pressure contained therein, a blowoff cock is preferably secured in an opening I! formed in the rear portion l2 to prevent overstressing of the housing and breakage of the parts therein.

Located in the housing I 0 is a float l8 which is raised or lowered according to changes in the level of the liquid in the housing [0. This float I8 is secured to one end of a rod 19 by means of a nut 20. The other end of the rod 19 is rigidly secured to oppositely extending arms 24 and 25 by means of screws 22 and nuts 23. The arms 23 and 25 are clamped against the rod 19 by drawing up the nuts 23 on the screws 22. The ends of these arms 24 and 25 are provided with inwardly extending pivots 26 riveted thereto for pivotally supporting the float assembly.

Secured on the inner side of the housing III by means of screws 30 is a guard 28 in the form of a U-shaped strip having an opening 29 therein 'which serves as abutments to limit the upward and downward movement of the float IS.

A plug 3| is screw-threaded in the housing In and has secured thereto one end of a bellows 32, and the other end of the bellow 32 is secured to the rod l9, as at 33. A gasket 34 is interposed between the plug 3| and the housing Hi, the gasket 34 and the bellows 32 forming an eiiicient seal for the float chamber l0.

Secured to the outer side of the housing III by means of screws 36 is a casing 35 which has rearwardly extending flanges 31 punched out 01' the back wall thereof to receive the pivots 26 of the arms 24 and 25. It will be noted at this point that the arms 24 and 25 of the float assembly extend rearwardly and are pivoted at 26 to the rearwardly extending flanges 31 at a point intermediate the ends of the sealing bellows 32, as shown in Fig. 1. By this construction, a real benefit is obtained in that undue straining and stressing of the bellows 32 by upward and downward movement of the float I8 is eliminated by evenly distributing the stresses throughout the bellows 32, whereby resistance to the movement of the float l8 by the bellows 32 is substantially decreased.

38 is a supporting member having ears 39 by which it is secured'to the back wall of the casing 35 by means of screws 40 extended through the cars 39. The supporting member 38 has a screwthreaded opening 4| located adjacent the top thereof and a hole 42 located near the bottom.

43 designates a spacer in the form of a washer having an opening 44 therein, which opening is larger than the opening 42 of the supporting member 38.

45 designates a driving lever having a hole 46 in the upper portion thereof and a hole 41 located substantially in its center and of substantially the same size as the hole 44 of the spacer 43. Extending laterally from the driving lever 45 is a projection 48, and extending downwardly from the driving lever 45 is another projection 49. A movable projection 50 extends downwardly from the driving lever 45 and is pivotally secured to the lower portion thereof by means of a screw 5|. The projection 50 is normally urged in a counterclockwise direction, as viewed in Fig. 2, by means of a tension spring 54 being secured between a pin 52 located on the projection 50 and a. pin 53 located on the driving lever 45. Counter-clock wise movement of the projection 50 is limited by means of a lug 55 integral with the projection 50 which engages an abutment pin 56 on the driving lever 45. This construction, as will be more fully pointed out hereafter, formsastrainreleasewhich is a, vital feature of this invention. The top of the lever 45 is notched as at 51 to cooperate with a latch 1|, as will be more clearly pointed out hereafter.

A mercury switch clip supporting member 58 has a hole 59 of substantially the same size as the hole 61 of the driving lever 45 and is also provided with forwardly projecting lugs 6h. The upper portion of this mercury switch clip supporting member 58 is provided with a vertical notch 6|.

A mercury switch clip 63 has a hole 65 of the same diameter as the hole 5d of the mercury switch clip supporting member 553 and is adapted to engage the supporting member 58 between the forwardly extending lugs 6d thereof. The mercury switch clip 83 has spring fingers 56 adapted to receive a mercury switch tube it.

66 designates generally a special form'oi rivet havingta; head 51, a shoulder 58 adapted to fit in the holes 65, 59, 11, and 5d of the mercury switch clip the mercury switch clip supporting member 53, the driving lever G5, and the spacer lt, repectively, and an extension ii adapted to fit in the hole of the supporting member The parts above described are assembled by placing the mercury switch clip the mercury switch clip supporting member the driving lever and, the spacer l -3 on the shoulder oi the rivet GE, and by inserting the extension of the rivet 563 through the hole of the porting member 38 and riveting over the end of the extension 69. In this manner, the parts are pivotally mounted on the supporting member 38.

10 designates an eccentric rivet riveted in the hole 46 of the driving lever 45, its head lying in the notch 6| of the mercury switch clip supporting member 58, whereby turning of the eccentric rivet 10 angularly adjusts the mercury switch clip supporting member 58 and consequently the mercury switch tube 16 with respect to the driving lever 45.

The latch 1| which cooperates with the notch 51 of the driving lever 45 has an upstanding arm 12 extending through a slot 15 in the top wall of the casing 35. The latch 1| is secured to and spaced from the supporting member 38 by means of a spacer 14 and a screw 13 extending into the screw-threaded opening 4| of the supporting member 38. The lower portion of the latch 1| is heavily weighted so that the latch 1| is at all times urged in a counter-clockwise direction, or latching position, by gravity.

The mercury switch tube 16 which is mounted in the spring fingers 64 of the mercury switch clip 63 is provided with conventional contacts 11 so located therein that when the tube is tilted ina clockwise direction the contacts are engaged by the usual mercury contained in the tube 16 to close an electrical circuit, and when the tube 15 is rotated in a counter-clockwise direction the mercury disengages the contacts 11 to open the electrical circuit. The contacts 11 are connected to fiexible lead wires 18 which extend to and are secured to a terminal block 19, as shown in Fig. 1.

Riveted on the pivoted arm 24 of the float assembly is an actuating pin which extends outwardly and below the projection 48 of the driving lever 45 so that upon downward movement of the float l8 in the float chamber caused by lowering of the liquid level therein, pin 80 is raised to contact projection 48 of the driving lever 45 to rotate the driving lever 45 in a counterclockwise direction to open the circuit in the mercury tube switch 15.

82 designates a pressure pipe which is adapted to be secured to a source of pressure that is also to control the operation of the instrument. The pressure pipe 82 may conveniently be secured into the float chamber II] to convey the pressures existing therein. If the float chamber I0 is provided with a pressure blow-ofi cook, the pressure pipe 62 may be connected to the high pressure side of the blow-off cook. The pressure pipe 82 is screw-threaded in a plug 83 which is riveted and soldered to a pressure casing 84, which pressure casing 84 is secured to the lower wall of the casing 35 by means of screws 8|. A pressure responsive bellows 85 is located within the pressure casing 85 and is suitably secured at its upper end to a plate 85 soldered to the pressure casing 85 and is secured at its lower end to a plate 81 that carries a plunger 88. Secured to the upper end of the plunger 88 is an adjustable actuator 89 having a pivot point 90.

The pivot point 9% of the plunger 88 engages a concave member 93 suitably secured to a lever The lever 92 has concavo-convex portions which engage knife edges l of a knife edge supporting member The supporting member 95 is rearwar-dly provided with a flange 96 which is riveted to the back wall of the casing 35 rigidiy to support the knife edge supporting member $52. The supporting member 55 has outwardly extending lugs 91 adjacent the "nife edges which encompassed by arms 9531 of the lever 92 to maintain the parts in their assembled relation.

The lever 92 is punched out as at 99 to form a means for securing one end of a tension spring 500 to the lever 92. The other end of the tension spring I00 is secured to a grooved nut IOI which is screw-threaded on a screw I02 that extends upwardly through the upper wall of the casing 35, the head I03 of the screw I02 engaging the outer surface of the casing 35. By turning the screw I02 by means of the external screw head 603, more or less tension may be placed in the spring I00. Riveted to the side wall of the casing 35 is a stop member comprising an upper 'stop I04 and a lower stop I05 to limit the amount of movement of the lever 92.

From the above it is seen that the tension spring 900 urges the lever 92 in a counter-clockwise direction about the knife edges 94, and that the pressure bellows 85 urges the lever 92 in a clockwise direction about the knife edges 94, the upper and lower stops I04 and I05 limiting such counter-clockwise and clockwise movements of the lever 92.

Integral with and extending upwardly from the lever 92 is an actuating arm I08 that is provided with a forwardly extending pin I01 which extends between the downwardly extending projections 49 and 50 of the driving lever 45. By this construction the pin I01 normally engages-the downwardly extending projection 50 and, through the spring 54, urges the mercury switch 16 in a. clockwise direction to maintain the electrical circuit closed when the force in the spring I00 is greater than the pressure acting on the bellows 85. The spring 54 is so chosen that it is of just suillcient strength to overcome the friction of the moving parts pivoted on the rivet 68. When the pressure as conveyed by the pipe 82 increases so that it overcomes the force in the spring I00, pin I01 is moved to the right to engage downwardly extending projection 49 of the driving lever 45 to rotate the switch 16 in a counterclockwise direction to open the circuit,

Mounted on both side walls of the casing 24 are U-shaped brackets having a rear arm I08 to which is secured the terminal block 19 by means of screws I09 and a front arm IIO to which is secured the cover II2 by means of screws III.

The operation of the control mechanism is as follows: when the liquid level in the float chamber I0 is at a proper height, the float I8 is maintained in its upper position, and the pin is out of engagement with the projection 48. When the pressure is normal, the spring I00 maintains the lever 92 against the stop I04 and the pin I01 against the downwardly extending projection 50 of the driving lever 45 to maintain the switch in closed or operative position, as shown in Fig. 6.

When the pressure as conveyed by pipe 82 becomes excessive it acts upon the bellows to overcome the tension in the spring I00 to force the lever 92 against the lower stop I05 to move the pin I01 to the right into engagement with the downwardly extending projection 49 of the driving lever 45 to move the switch 16 in a counter-clockwise direction to inoperative or circuit open position, as shown in Fig. 5. It will be noted in Fig. 5 that the laterally extending projection 48 has moved away from pin 80.

Assuming that the pressure as conveyed by pipe 82 is normal, the pin I01 engages the downwardly extending projection 50 of the driving lever 45 to maintain the switch in its closed or operative position, but when the level of the liquid in the float chamber I0 becomes abnormally low, the float I8 moves downwardly to move pin 80 upwardly into engagement with the laterally extending projection 48 of the driving lever 45 to rotate the switch in a counter-clockwise direction to inoperative or open position, as shown in Fig. 4. Because of the fact that the pressure acting on the bellows 85 is normal, some means must be provided to allow this movement of the switch to inoperative position by the pin 80. This means is accomplished by use of a strain release in the form of the tension spring 54 which is sufiiciently strong normally to urge the switch to circuit closed position, but not strong enough to overcome the action of the pin 80 as it is moved upwardly by a lowering of the level of the liquid in the float chamber I0. Fig. 4 shows the spring 54 in its strained position and clearly sets forth the operation of the strain release connection between the pressure actuated pin I01 and the driving lever 45 Whenever the driving lever 45 is moved sufliciently far in a counter-clockwise direction, the latch 1I drops into the notch 51 of the driving lever 45, holding the driving lever 45 in that position until the latch TI is manually released by means of the handle 12. The driving lever 45 is so moved into latching position when an undesirably low liquid lever exists in the float chamber I0. Float I8 lowers and raises pin 80 which engages the projection 48 to move the driving lever 45 in a counter-clockwise direction to permit the latch H to engage in notch 51. However, the

driving lever 45 is not moved into latching posltion upon a rise in pressure acting on the bellows 85 because the bottom stop I 05 limits the clockwise movement of the lever 92 and the consequent counter-clockwise movement of the driving lever 45. By reason of the lower stop I05, the driving lever 45 cannot be moved sufliciently far to allow the latch H to drop into notch 51.

From the above construction and operation a very desirable result is obtained in that upon low liquid level and for high pressure the switch is opened, and it may be automatically closed when the liquid level and the pressure return to their proper values, but when the liquid level becomes abnormally low the switch is latched in open posi-.

tion requiring manual intervention to allow the switch to be closed.

If the control system of this invention should be applied in a system where it would be advantageous to latch the switching mechanism in an open or inoperative position upon the existence of an abnormally high pressure acting on the bellows 85, the lower stop I05 could be lowered to permit further counter-clockwise movement of the driving lever 45 whereby the latch 1I could engage in the notch 51.

If it is desired to have the control mechanism automatically resume operation both when the liquid level has been restored and when the pressure as conveyed by pipe 82 has been decreased,

the latching mechanism 1I may be omitted entirely. When the latching mechanism is so omitted, the control mechanism is completely automatic in its operation.

From the above it is seen that I have invented a combined liquid level and pressure control for operating a device such as a swltch wherein the device or switch is moved to an open or inoperative position by an abnormal condition existing in the float chamber or by an abnormal condition of pressure, and wherein these changes in conditions act independently of each other on the control mechanism.

While one embodiment of this invention has been shown and described, it is obvious that many modifications may be apparent to one skilled in the art, and consequently this invention is to be limited only by the scope of'the appended claims and the prior art.

I claim:

1. In a device of the character described, a float chamber, a float in said float chamber and adapted to be raised or lowered by changes in liquid level in said chamber, a bellows adapted to be.

expanded and contracted by changes in pressure, a switch movable to operative and inoperative positions, a pivoted lever for moving said switch, a fixed projection on said lever, a pin operatively connected to said float to engage said projection to move said switch to inoperative position when said liquid level reaches a predetermined minimum, a second fixed projection on said lever, a second pin operatively connected to said bellows to engage said second projection to move said switch to inoperative position when said pressure reaches a predetermined maximum, a resilient projection on said lever to be engaged by said second pin normally to maintain said switch in operative position when said pressure ing means associated with said lever to maintain said switch in inoperative position when said switch is moved to inoperative position by one of said pins.

2. In a device of the character described, a float chamber, a float in said float chamber and adapted to be raised or loweredby changes in liquid level in said chamber, a bellows adapted to be expanded and contracted by changes in pressure, a switch movable to operative and inoperative positions, a pivoted lever for moving said switch, a fixed projection on said lever, a pin operatively connected to said float to engage said projection to move said switch to inoperative position when said liquid level reaches a predetermined minimum, a second fixed projection on said lever, a second pin operatively connected to said bellows to engage said second projection to move said switch to inoperative position when r adapted to be raised and lowered by changes in means operatively connected to said float and liquid level in said chamber, a bellows adapted to be expanded andcontracted by changes in pressure, a switch movable to operative and inoperative positions, a member for moving said switch,

associated with said member to move said switch to inoperative positions when said liquid level reaches a predetermined minimum, means operatively connected to said bellows and associated with said member to move said switch to inopertive position when said pressure reaches a predetermined maximum and to maintain said switch in operative position whensaid pressure is less than said predetermined maximum but allowing said switch to bemoved to inoperative position by said first mentioned means, and means associated with said member to maintain said switch in inoperative position when said switch is moved to inoperative position by one of said means. I

4. In a device of the character described, a float chamber, a float in said float chamber and adapted to be raised and lowered by changes in liquid level in said chamber, a bellows adapted to be expanded and contracted by changes in pressure, a movable control member, a projection on said control member, a. pin operatively connected to said float to engage said projection to move said controlmember in one direction when said liquid level reaches a predetermined minimum, a second projection on said control member, a second pin operatively connected to said bellows to engage said second projection to move said control member in the same direction when said pressure reaches a predetermined maximum, a resilient projection on said control member to be engaged by said second pin to move said control member in a second direction when said pressure maintain said control member in its shifted position when moved in said first direction by one of said pins. 1

5. In a device of the character described, a fioat chamber, a float in said chamber and adapted to be raised and lowered by changes in a liquid level in said chamber, a bellows adapted to be expanded and contracted by changes in pressure, a movable control member, means operatively connected with said float and associated with said control member to move said control member in one direction when said liquid level reaches a predetermined minimum, means operatively connected to said bellows and associated with said control member to move said control member in the same direction when said pressure reaches a predetermined maximum and'to move said control member in a second direction when said pressure is less than said predetermined maximum but allowing said control member to be moved in said first direction by said first mentioned means, and means associated with said control member to maintain said control member in it's shifted position when moved in said first direction by one of said means.

6. In a device of the character described, a movable control member, means responsive to changes in a liquid level to move said control member in one direction when said liquid level reaches a predeterminedminimum, means responsive to changes in pressure to move said control member in the same direction when said pressure reaches a predetermined maximum and to move said control member in a second direction when said pressure is less than said predetermined maximum but allowing said control mem- -ber to be moved in said flrstdirection by said first mentioned means, and means associated with said control member to maintain said control member in its shifted position when moved in said first direction by one of said means.

'1 In a device of the character described, a switch movable to operative and inoperative posithus, a member for moving said switch, means responsiveto changes in liquid level associated with said member to move said switch to inopera- A tive positiommeans responsive to changes in pressure associated with said member to move said switch to inoperative position and to maintain said switch in operative position during normal pressure conditions but allowing said switch to be moved to inoperative position by said first means, and means associated with said member to maintain said switch in inoperative position when said switch is moved to inoperative position by one of said means.

8. In a control mechanism, a movable control member, means responsive to changes in a condition for moving said member to a first position, means responsive to changes in another condition to move said control member to said first position and normally to maintain said control member in a second position but allowing movement 01' said control member to said first position by said first means, and means associated with said control member to maintain said member in said first position when moved to said first position by one of said means.

9. In a control mechanism, a switch movable to open and closed positions, means responsive to normal pressure conditions normally to maintain said switch in closed position and to move said switch to open position in response to abnormal pressure conditions, means responsive to abnormal-liquid level conditions to move said switch to open position independent of said pressure conditions, and means to latch said switch in open position.

10. In combination, a member to be controlled and movable in first and second directions, latching means associated with said member to be controlled and operative to latch said member to be controlled when moved sufllciently far in said first direction to then prevent return movement thereoi. in said second direction, first and second actuators associated with said member to be controlled and both operative to move said member to be controlled sufllciently farin said first direction to cause the same to be latched by said latching means, and restraining means associated with one of said actuators to prevent the same from moving said member to be controlled sufiiciently far in said first direction to cause latching thereof.

11. In combination, a movable control member,

a projection on said control member, means ineluding a pin for engaging said projection to move said control member in one direction, a second projection on said control member, means including a second pin for engaging said second projection to move said control member in the same direction, and-a resilient projection on said control member to be engaged by said second pin to move said control member in a second direction and adapted to yield when the control member is moved in the first direction by the first pin.

12. In combination, a movable control member, a projection on said control member, means including a pin for engaging said projection to move said control member in one direction, a second projection on said control member, means including a second pin for engaging said second projection to move said control member in the same direction, a resilient projection on said control member to be engaged by said second pin to move said control member in a second direction and adapted to yield when the control member is moved in the first direction by the first pin, and means associated with said control member to maintain said control member in its shifted position when moved in said first direction.

13. In combination, a movable control member,

abutment means on said control member, means for engaging said abutment means to move said control means in one direction, second abutment means on said control member, second means for engaging said second abutment means to move said control means in the same direction, yieldable abutment means on said control member to be engaged bysaid second means to move said control member in the other direction and. adapted to yield when the control member ismoved in the first direction by the first means, and latch means associated with said control member to hold said control member in its shifted position when moved in said first direction by said first abutment means, said latch means remaining inoperative when said control member is moved by said second abutment means.

14. In combination, a movable control member, abutment means on said control member, means for engaging said abutment means to move said control means in one direction, second abutment means on said control member, second means for engaging said second abutment means to move said control means in'the same direction, yieldable abutment means on said control member to be engaged by said second means to move said control member in the other direction and adapted to yield when the control member is moved in the first direction by the first means, and means associated with said control member to maintain said control member in its shifted position when moved in said first direction.

15. In combination, switch means movable to open and closed positions, pressure responsive means operable to move said switch means to open and closed positions respectively upon the achievement of predetermined high and low pressures, liquid level responsive means operable to move said switch to open position upon the achievement of a predetermined low liquid level, latch means associated with said switch means operable to hold the same in open position when moved by said liquid level responsive means upon the achievement of said low liquid level and means associated with said pressure responsive means for preventing it from latching said switch means in open position upon achievement of said predetermined high pressure.

16. In combination, a control member, first means for controlling the movement of said control member in either of two directions, second .means for controlling the movement of said control member in either of two directions, latch means positioned to be engaged by said control member when moved a predetermined amount in one direction by one of said means, and means preventing the other of said control means from moving said control member far enough to engage said latch means.

17. In a device of the character described, a float chamber, a float in said fioat chamber and adapted to be raised and lowered by changes in liquid level in said chamber, a bellows adapted to be expanded and contracted by changes in pressure, a movable control member, a projection on said control member, a pin operatively connected to said fioat to engage said projection to move said control member in one direction when said liquid level reaches a predetermined minimum, a second projection on said control member, a second pin operatively connected to said bellows to engage said second projection to move said control member in the same direction when said pressure reaches a predetermined maximum, and a resilient projection on said control member to be engaged by said second pin to move said control member in a second direction when said pressure is less than said predetermined maximum and adapted to yield when said control member is moved in the first direction by said first pin.

18. In combination, a movable control member, I

pressure responsive means for moving said control member in one direction, liquid level responsivemeans for moving said member in the same direction and means for latching said member in its shifted position when moved by said liquid 5 level responsive means.

' CARL G. KRONMILLER.

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