US2204325A

US2204325A - Centrifugal control

Info

Publication number: US2204325A
Application number: US143087A
Authority: US
Inventors: Joseph H Staley
Original assignee: ELECTRIC SWITCH CORP
Current assignee: ELECTRIC SWITCH Corp
Priority date: 1937-05-17
Filing date: 1937-05-17
Publication date: 1940-06-11
Anticipated expiration: 1957-06-11

Description

June ll, 1.940.` 1 STALEY 2,204,325

CENTRIFUGAL CONTROL Filed lay 17, 1937 5 Sheets-Sheet 1 5 Sheets-Sheet 2 J. H. STALEY CENTRIFUGAL CONTROL Filed lay 17, 1937 June ll, 1940.

M, n w H. vf 5 J0 Jun l1, 1940. J. H. sTALEY CENTRIFUGL GONTROL Filed Ilay 17, 1937 5 Sheets-Sheet 3 m @E @E l @m WQW m f @QN Q@ EN @uw @NN Mmmm N @N :mln

um m91 @NN @QN 4/ N www QQ Nm 9N w www CENTRIFUGAL CONTROL Filed lay 1'7, 1937 5 Sheets-Sheet 4 Patented June l1, 1940 y y UNITED STATES PATENT OFFICE CENTRIFUGAL CONTROL Joseph H. Staley, Columbus, Ind., assignor to Electric Switch Corporation, Columbus, Ind., a corporation of Indiana Application May 17, 1937, Serial No. 143,087

25 Claims. (Cl. Z00-80) My invention relates to a centrifugal control Fig. 2 is a sectional view, taken along the line adapted for operative association with rotary 2 2 in Fig. l, looking in the direction of the machines generally for the purpose of controlling arrows.

the speed of the associated or other machines, Fig. 3 is a vertical, sectional elevation of a and the operation of mechanical and electrical modified type of control.

devices generally, including the making and Fig. 4 is a section along the line 4 4 in Fig. 3, breaking of electric' circuits, and is particularly looking in the direction of the arrows. concerned with providing a control having a Fig. 5 is a sectional elevation showing another mercury switch or generally a switch of the fluid modification of my improved control.

l0 flow type as the centrifugally operated member. Fig. 6 is an elevation of the upper portion of l0 Mercury switches have heretofore been centhe control, as viewed in Fig. 5.

trlfugally controlled to determine various condi- Figs. '7 and 8 are sections along the lines 1 1 tions of operation. These previous embodiments and 8 8, respectively, in Fig. 6, looking in the have generally taken the form of a rockable or direction of the arrows.

rotatable mercury tube switch which is actuated Fig. 9 is a section along the line 9 9 in Fig. 5, 15

by a remote, centrifugally controlled member, looking in the direction of the arrows.

or a switch which is rotated about its axis to dis- Fig. 10 is a sectional elevation of a further place the mercury along the sides of the tube, or modification of my improved centrifugal control. a switch which is fixed in position relative to a Fig. 11 is a sectional plan view taken along the 2o support carried by a rotary shaft, for example. line II II in Fig. 10, looking in the direction of 20 In the latter case, the switch tube is usually inthe arrows. clined to the shaft. Fig. 12 is a fragmentary, elevation view, look- Such switch constructions, however, are charing in the direction of the arrow I2 in Fig. l0, acterized by sluggishness, jerkiness and irreguand showing the use of a torsion spring to conlarity in operation and are incapable of being trol the mercury switch. 25 finely governed, particularly where used to con- Referring to Figs. 1 and 2 of the drawings trol the speed of rotary machines, such as electric which illustrate one structural arrangement of motors. Under the latter condition, the motor my improved centrifugal control, the numeral II tends to fall into a state of speed oscillation, or designates a shaft, or generally any rotary so-called huntingj in which the governor flucmember, which is shown in a vertical position, 30 tuates over a wide range in its endeavor to find although the control may be located horizontally the desired speed. Where the maintenance of a when used with a horizontal shaft, or in any denite speed within close limits is a condition position intermediate a horizontal and vertical of operation, such fiuctuation is undesirable. pOSitOrl- The Control, deOted generically by It is therefore one object of my invention to the numeral I2 in Fig. l, is mounted on the 35 devise a centrifugal control employing a merupper end of the shaft II, as presently described. cury switch which is characterized by a greater Referring more particularly to Fig. l, the consensitivity and neness of control relative to trol I2 includes a disk I3 having a hub I4 deexisting devices intended for the same character pending from the underside thereof which is 0f Operation, provided with a threaded extension I5 that is 40 A further object is to provide a control of the xedly mOuntEd in the upper end 0f the Shaft II. character indicated in which the mercury switch A block I6, preferably composed of insulating is at all times, during the operation of the assomaterial, is fixedly mounted on the top of the ciatcd machine, subjected to a resilient restraint disk I3 in offset relation to the axis of the shaft II that is independent of the centrifugal force actand this block may be provided with a plurality 45 ing on the switch. of adjustment apertures Il. In one of these These and further objects of my invention will apertures is mounted a pin I8 whose ends are be set forth in the following specification, refcrjournaled in a pair of ears I9 that straddle the ence being had to the accompanying drawings, block i6 and which depend downwardly from a and the novel means by which said objects are strap 20 that is appropriately clamped to the 50 effectuated will be definitely pointed out in the lower end of a mercury tube switch 2I. claims. The lower end of the switch is formed by a In the drawings: hollow metallic cylinder 22 whose bottom end is Fig.'1 is an enlarged, sectional elevation of one closed and gripped by the metallic strap 20. A form of my improved control. sleeve of insulating material 23 fits closely within 55 ment to the indicated collector rings.

the upper end of the cylinder 22 and extends downwardly to a point adjacent the bottom thereof. Fitting closely within the sleeve 23 is the cylindrical portion of an upper metallic member 24 that is appropriately encircled and clamped by a metallic strap 25. The cylinder 22 and member 24 constitute the electrodes of the mercury switch which, when the switch is occupying the position illustrated in Fig. l, are electrically connected by a globule of mercury 2B. The lowei` end of the member 24 may terminate flush with the lower end of the sleeve 23 and a breaker ring 2lia fills the space between the ends of the sleeve and member, and the bottom end of the cylinder. The inner wall forms a continuation of the inner wall of the member 24 and is preferably composed of a suitable refractory material in order to withstand the intense heat of any arcing.

The mercury switch per se forms no part of the present invention, and its illustration in detail is not to be regarded as restricting the use of the invention to the particular switch shown. Other types of iiuid flow switches may be employed as desired for this modification and those presently described.

A pair oi' spaced ears 21 project upwardly from the top of the member 25 and bridged between these ears is a pin 28 that is encircled by one end of a helical spring 29 whose opposite end is secured to a screw 30 that is threaded through the upper end of a post 3|. The screw 30 may be adjusted endwise to establish any desired tension in the spring and this adjustment may be held by lock nuts 32. The post 3| projects upwardly from the disk |3 and is fixed in position relative thereto by means of a cap screw 33 which is appropriately insulated from the disk, as is also the post.

The post 3i is located on the opposite side of the axis of the shaft from the switch and, in addition to serving as a fastening support for the spring 29, also acts as a counterbalance weight for the switch and prevents any whipping tendency of the disk i3 which would otherwise introduce disturbing force factors in the operation of the switch. The weight of the post and the radial distance of its center of gravity from the axis of the shaft are so related with reference to the similar characteristics of the switch 2| that the desired counterbalancing effect is obtained.

An electric cable 34 has one end fastened to the strap 2D and the opposite end to a collector ring 35, while a similar cable 36 has its opposite ends secured to the strap 25 and a collector ring 3T. respectively. The rings are spaced from each other, as indicated in Fig. l, and encircle an insulating sleeve 38 which is mounted on the hub I4. The lower ends of the cables extend downwardly through a cavity 39 provided in the hub and then outwardly through appropriate apertures in the hub and the sleeve 38 for attach- Accordingly, when the switch is occupying the position illustrated in Fig. l, the rings and 3T are electrically connected through the cable 34, strap 2U, cylinder 22, mercury 25, member 24, strap 25, and cable 35.

The rings 35 and 3l are constantly engaged by the protruding ends of a pair of wipers 40 and 4I, respectively, which are slidably mounted within a pair of metallic sleeves 42 and d3, respectively, provided in a casing 44 that is preferably composed of insulating material. The wipers 40 and 4| are held against the indicated rings by means of a pair of coil springs 45 and 46, respectively. which additionally bear against metallic cap plates 41 and 48, respectively. The casing 44 may be carried on an arm 49 that is supported by a bracket 50 that may be attached to any convenient part (not shown).

The cap plates 41 and 48 may bc connected by wires 5| and 52, respectively, to a circuit (not shown) forming part of thc device whose speed it is desired to control.

The major features of my centrifugal control may be enclosed by a cylindrical casing 56 having a cover 51 which is retained in position by a pair of long cap screws 58 that extend through the cover and are threaded in the disk I3.

ln describing the operation of the control as above set forth, it will be assumed that the shaft l constitutes the shaft of a series motor, which is started under load, and that it is desired to regulate the speed of the motor within narrow limits.

At the instant of starting, the mercury switch 2| occupies the position illustrated in Fig. 1, that is. with its longitudinal axis substantially parallel to the axis of the shaft although it will be understood that the screw 30 may be adjusted so as to incline the upper end of the switch towards the shaft axis in the general manner hereinafter described for modified types of the control.

As the speed of rotation of the shaft increases, the mercury switch 2| swings outwardly due to centrifugal force and against the tensional pull of the spring 23. Eventually, the switch is moved to a position in which the mercury globule 26 is moved upwardly along the inclined, outer surface of the member 24 by the centrifugal force to an extent sufficient to break the electric circuit between the electrodes of the switch. Immediately, the motor armature begins to decrease in speed, thus decreasing the centrifugal force and enabling the spring 29 to retract the switch inwardly towards its original position. This action enables the mercury to again complete the circuit between the electrodes and thus re-establish the current through the motor.

The principal factors which are operating during the foregoing action are centrifugal force, centrifugal force exemplified by the pull of the spring 29, the force of gravity, the cohesion and f surface tension of the mercury and the action of the mercury on the variable inclined surface provided by the electrode 24. The numerical value of the centrifugal force acting on the switch at any instant is determined approximately by 5 the weight and velocity of the switch in accordance with the following formula:

in which F is the centrifugal force, W is the weight of the mercury switch tube, V is the linear velocity of the center of gravity of the switch, G is the acceleration of gravity, and R is the radius 0f the center of gravity of the switch from the axis of the motor shaft. This formula is approximate for the switchltube due to the fact that the tube is tied at one end, but is substantialy accurate for the globule of mercury owing to its freedom of movement.

Due to the restraint exerted by the spring 29 on the free end of the switch tube, the tube is always subjected to a retracting force which is independent of centrifugal action and which is available to retract the switch as soon as the G fr circuit through the motor is broken and the latter begins to reduce in speed. The practical effect of this condition is that a motor which is speed governed by this control is entirely free of the jerky action which would characterize a control having a mercury switch that was fixed in position. ln the latter ca'se, the mercury would be shifted to the top end of the switch and would be retained there until the motor had decreased in speed suiliciently to enable the mercury to return to a circuit making position. The heavy impulse then exerted by the electric current would frequently cause the motor to exceed the desired speed, so that the mercury would be again thrown towards the upper end of the switch, the circuit broken, and the foregoing action then repeated. Close speed regulation under these conditions is obviously impossible.

In my control, while the action within the switch at high speeds cannot be observed, it is considered that the probable situation is that the mercury is forced by centrifugal action into intimate contact with the outer surface of the electrode 2l and assumes an elongated shape, rather than the natural mercurial globule. This attened and elongated shape gradually creeps upwardly along the wall of the electrode 24 until, at the controlled speed, as determined by the setting and number of coils in the spring 29 and the radial distance of the pin I8 from the axis of the shaft, the lower end of this ilattened shape breaks contact with the electrode 22. Immediately, the spring 29, as the motor decreases very slightly in speed, draws the switch inwardly and the circuit is again completed through the switch. This action is repeated within a narrow speed band which includes the desired speed and, in essence, the situation is such that a high frequency succession of circuit interruptions is obtained substantially at the controlled speed.

In the vertical application of the control. as shown, the force of gravity acting on the mercury plays a very important part in the operation of the device, as does the natural cohesion and surface tension of the mercury. Moreover, as the motor increases in speed from a starting condition, it is obvious that, as the switch pivots outwardly, the numerical value of the centrifugal force operating on the switch per se increases, due to the increasing radius of the center of gravity of the switch from the axis of the motor and the increasing linear velocity of the center of gravity of the switch. The same condition holds true with respect to the mercury itself, since as it moves upwardly along lthe wall of the electrode 24. its center of gravity moves farther from the axis of the motor shaft.

The control may be nely governed by varying the pivot position of the switch with reference to the shaft ll and by regulating the initial tension of the spring 29. A further controlling factor may be introduced by suitably conditioning the wall of the switch electrode 24, i. e., providing this wall with a rough or a smooth surface in order to increase or decrease the facility with whichI the mercury may move along the wall.

Referring to Figs. 3 and 4, there is illustrated a modification of my improved control which employs a pivoted, counterbalance member, as contrasted with the fixed member in Fig. 1, and, further, in which the counterbalance member is used to complete the electrical circuit through the control.

Referring to Fig. 3, the numeral 59 designates a hub having integrally formed therewith a pair of oppositely extending arms -60 and which is preferably composed of suitable insulating material. The hub is pinned to a spindle 6| whose lower end is pinned or otherwise secured to a shaft 62, which may be the shaft of a motor or, generally, any rotary member. The upper end of the spindle 6l is journaled in the top of a casing 63 which encloses the parts presently described.

A pivot pin 64 extends through the left arm 60, as viewed in Figs. 3 and 4. and straddling this` arm is a pair of ears 65 which are rotatably supported on the exposed ends of the pin 64. The ears 65 depend from a metallic strap 66 which is clamped around the lower end oi a mercury tube switch 61 and, specifically, around the lower cylindrical electrode 68. The construction of this tube switch may be and, for purpose of illustration, will be deemed to be identical with that illustrated in Fig. 1, except for a breaker ring similar to the ring 26n in Fig. l, although such a ring may be used with this embodiment. Accordingly, the switch will comprise, in addition to the lower electrode 68, an upper electrode 69 that is insulated from the electrode 68, and a globule of mercury 10, for electrically connecting the electrodes.

The upper end of the electrode 69 is encircled and clamped by a metallic strap 'il having an upwardly extending ear l2 to which is secured one end of a helical spring 13 whose opposite end is secured to a nut 14 that is mounted on thespindle 6|.

In the opposite arm 60 is mounted a pin l5, and a pair of spaced ears 'I6 embrace the opposite sides of the arm and are journaled on the ends oi' the pin, The ears 16 depend from a metallic strap l1 which is clamped around the lower end of a metallic, counterbalance member 18 whose upper end is clamped by a metallic strap 19. This strap is provided with an upwardly extending ear 80, and fastened thereto is one end of a helical spring 8| whose opposite end is attached to the nut 74. The distribution of mass in the member 'i8 approximates that in the switch 6.1, and the radial distances of the centers of gravity of these parts from the spindle Sl are the same at all times so that, at high speeds, the spindle 6| will rotate without Whipping.

The straps 7| and 'I9 are electrically connected by a cable 82 and one end of a wire 83 is coiled around and in electrical connection with the pin 615i, the opposite end of the Wire being secured to a collector ring 84 that encircles and is embedded in the hub The intermediate portion of the wire 83 extends through the body of the hub. Similarly. one end of a wire 85 is wound around and in electrical contact with the pin l5 and this wire is 'then led through the body of the hub E9 for afiixation to a collector ring 86 which also cncircles the hub. The collector rings occupy the spaced relation illustrated in Fig. 3 and are in electrical communication through the control by means of the wire t3, pin 64. cars 65, mercury switch 67 (when the mercury l0 is occupying the position illustrated in Fig. 3), strap 7|, cable 82, strap 19, member 18, strapV ll, ears 1S, pin l5, and wire 85,

A pair of metallic wipers 81 and 88 are slidably mounted in a casing 89 formed of insulating material and appropriately carried by the casing 63 and the outer ends of these wipers are pressed constantly against the collector rings 84 and 85, respectively, by means of a pair of coil springs 92 and 93, respectively, which are mounted in recesses in the casing 89. Metallic stems S and 9| are connected to the wipers 81 and I8, respectively, and extend externally of the casing 09 for connection to an electric circuit.

When the control is rotating at relatively low speeds, the lower ends of the switch B1 and member '18 rest on and are in electrical contact with a shorting ring 94 which is mounted on the upper end of the hub 59. This ring is electrically connected to the wire 85 by a wire 94. Accordingly, when the circuit is completed through the control, the current is short-circuited through the ring until the control attains a speed of rotation at which the mercury switch swings outward.

The operation of the control illustrated in Fig. 3, so far as the mercury switch is concerned, is identical with that heretofore described except that, due to the retention of a globule of mercury beneath the shoulder formed by the lower ends of the insulating sleeve and electrode 69, the make and break of the switch is between globules of mercury. It will be understood that the spring 'i3 may be provided with any desired initial tension in order to secure the required operation of the control. The principal distinction between this modification and the one heretofore described resides in the use of the pivoted counterbalance member 18 as a path for the flow of the electric current through the control.

In Figs. to 9, inclusive, there is illustrated a further modification of my control which is also characterized by the use of a pivoted counterbalance member, but is distinguished from the preceding embodiment in that this member is ,not employed as a part of the electric circuit through the control and also by the use of a Y diierent arrangement of spring action.

Referring to 5, the numeral 95 designates a shait which may be a motor shaft, or the shaft of any rota chine, or a shaft which is connected to etl rnotor or a machine, and which extends through and is journaled in a bearing S5 formed in the bottom plate of the control casing upper end of the shaft 95 may be sc u d to with... and drivably connect a cross aped plate S6 having the oppositely extending arms 99 an's |30, and |0| and |02, respectively. The plate 98 rests upon a disk |03 which in turn is supported on a spacer |04 that rests on the upper end of the bearing 96. Preferably, the plate 98, disk |03, and spacer |04 are formed of a suitable insulating material.

At a determined radial distance from the axis of the shaft 95, a pin |05 is mounted in the arm 99 and embracing the sides of this arm and journaled on the ends of the pin is a pair of ears |06 that depend from a metallic strap |01 which clamps the metallic lower end |08 of a mercury switch |09. The upper end of the switch is formed by a metallic part ||0 and it will be understood that, for purpose of illustration, the switch |09 may be identical in construction with those illustrated in Fig. 1 or 3, or in other words, that the parts |08 and ||0 constitute the electrodes of the switch which are insulated from each other and, when the switch is occupying the position illustrated in Fig. 5, are electrically connected by a mass of mercury .In Fig. 5, it will be noted that the axis of the mercury tube switch is inclined to the axis of the shaft 95, the upper end of the switch being closer to the shaft than the lower end.

The strap |01 is electrically connected by a cable |2 to a cap screw III that extends downwardly through the arm 99 and disk |03 for threaded engagement with an annular, collector ring II4. A similar cap screw extends through the arm |00 for engagement with the ring ||4.

A pin I I5 is also mounted in the arm |00 at the same radial distance from the axis of the shaft 85 as is the pin |05 and embracing the sides of this arm is a pair of ears IIB in which are iournaled the ends of the pin IIS. These ears depend from a strap which clamps the lower end of a counterbalance member I8. The function of this member is identical with the other counterbalance members heretofore described. except that, in the present instance, the member ||8 acts solely as a counterbalance and not as a path for the electric current through the control. When the control is at rest, the axis of the member ||8 makes the same angle with the axis of the'shaft 95 as does the axis of the mercury switch |09 and the inner edges of these parts may rest upon a metallic, shorting plate IIS that extends along the top surfaces of the arms |0| and |02.

A slightly different form of spring restraint is employed in this control modification and it takes the form of a pair of U-shaped spring members which are formed of fiat spring metal and which are located at the ends of the arms |0| and |02, respectively, or on opposite sides of the plane in which the switch and counterbalance member swing. These springs are identical in construction, so that it is only necessary to describe one of them in detail.

The member generally is denoted by the numeral |20 in Fig. 6 and it includes a base |2| that is received within a recess |22 that is notched on the underside of the extremity of the arm |0| (see Figs. 8 and 9) and it rest:` directly upon the top surface oi the disk |03. T. e spring arms |23 and |24 extend freely upwardly from the base |2| and their upper ends are curved outwardly and then downwardly into a substantially spiraliormation and are attached, respectively, to metallic straps |25 and |25 which clampjhe switch electrode and the upper end of the counterbalance member ||8, respectively.

Accordingly, as the switch and counterbalance member move outwardly under the impulse of centrifugal force, they are at all times subject to the resilient restraint imposed by the spring arms |23 and |24, including their spiral end formations.

As the spring arms |23 and |24 move outwardly and inwardly they are guided by and have electrical contact with the walls of recesses |21 provided in the opposite ends of a thin, guide plate which is adjustably mounted on a threaded stem |29 that extends downwardly through the arm |0| and also through the base |2| of the spring member, the disk |03, and is finally threaded in an annular, collecting ring |30 which abuts against the underside of the disk in spaced relation to the collector ring H4. The vertical position of the guide plate |20 may be maintained by top and bottom lock nuts |3| (see Fig. 9). A similar spring arrangement and guide control extends upwardly from the arm |02 and the ver-- tical rigidity and spacing of the threaded stems |29 is maintained by a strut |22 that extends between the mercury switch and counterbalance member and has its ends fastened to the upper ends of the stems,

I'he under surfaces of the collector rings ||4 and |30 are constantly engaged by wipers |33 |39, as illustrated in Fig. 10, the electrodes are and |34, respectively, which are appropriately insulated fromfeach other and held against their respective collector rings by springs |35 and |35. Wires |31 and |38 vextend outwardly .from the wipers |33 and |34, respectively, for connection to any desired electrical circuit.

When the parts are in the several positions illustrated in Fig. 5. electrical connection between the collector rings through the control is obtained by means of the cap screw ||3, cable ||2, strap |01, switch |09, clamp |25, spring arm |23, guide plate |28, and stem |29.

The operation of the embodiment illustrated in Fig. will be apparent from the foregoing dcscrlption. As far as the mercury switch action is concerned, it is substantially identical with that illustrated in Fig. l, except that the initially inclined position of the switch makes it possible to provide for a delayed interruption of the associated circuit at any given speed, dependent upon the setting and strength of the springs |20; Moreover, the member ||3 operates solely as a counterbalance weight. As in the case of the modification shown in Fig. 3, the current through the control is short-circuited through the plate ||9 when the control is rotating at relatively low speeds and this circuit is not opened until the mercury switch swings outward, whereupon the current passes through the switch. As clearly illustrated in Fig. 9, the plate ||9 is electrically connected to the ring |30 by the stems |29.

In Figs. to 12, inclusive, there is illustrated a further modification of my improved centrifugal control which differs from. that illustrated in Fig, 5 in that the counterbalance member is used as a part of the electric circuit through the control and also, most importantly, in the type of spring restraint which is imposed upon the parts of the control that are moved under the impulse of centrifugal force. As already described, the other types of control employ either helical or simple ilat springs, whereas the type of control now under discussion utilizes the torsional action of flat spring members which are held at their ends and twisted at their interme diate portions.

Referring to Fig. 10, the number |39 designates a shaft generally which ls subjected to a motion of rotation and whose upper end is secured to an encircling sleeve |40 that is received within a counterbore provided in the hub portion of a disk |4| that is preferably composed of insulating material. The shaft |39 is also pinned to this hub.

On the top surface of the disk |4I is mounted a pair of spaced cap screws |42 and bridged between these screws and with its ends secured thereto is a ilat metallic strip |43 composed of any suitable springy metal. This strip is offset from the axis of the shaft |39. A threaded stem |44 extends downwardly through the strip |43 midway of its ends and this stem depends from the underside of a metallic, sleeve socket |45 which receives the metallic, lower end |45 of a mercury tube switch |48. A sleeve nut |41 encircles the socket |45 and frictionally retains the lower end of the switch in position. The lower end member |45 constitutes one of the electrodes of the switch and the other electrode is constituted by an upper end member |49, the entire construction of the switch being similar, for example, to the mercury switches illustrated in Fig. l or 3. When the switch is occupying the inclined position relative to the axis of the shaft electrically connected by a mass of mercury |50.

One of the cap screws |42, and accordingly the electrode |46, is electrically connected by a cable |5| which extends downwardly through the insulating disk |4| for securement to a collector ring |52 that encircles the hub portion of the disk. The other electrode member |49 is electrically connected by a cable |53 to the top end of a metallic, counterbalance member |54 having a threaded stern that extends downwardlythrough the intermediate portion of a ilat, metallic, spring strip |56 whose ends are supported on a pair of cap screws |51 that are threaded in the disk |4| As clearly indicated in Fig. l1, the screws |42 and |51 are so positioned that the strips |43 and |55 are located on opposite sides of the axis of the shaft |39 and parallel to each other, thus insuring that the substantially pivotal connection of the mercury switch and counterbalance member to their respective spring strips are at the same radial distance from the axis of the shaft |39.

The peripheral surfaces of the rings |52 and |59 are constantly engaged by the ends of a pair of Wipers |50 and IGI, respectively, which are slidably mounted in metallic sleeves |52 and |53, respectively. These sleeves are carried by an insulating casing |64 that is attached to a bracket |55 which in turn may be supported by any external structure, such as the frame of a motor (not shown). The wipers |50 and |5| are yieldingly forced outwardly by coil springs |55 and 51, respectively, which are abutted by screws |58 and |59, respectively. Wires |10 and |1| are electrically connected to the screws |68 and |59, respectively, and may be connected to any desired electric circuit. The centrifugally operated por tions of my control may be enclosed within a casing |12 that is suitably carried by the disk |4|.

The action of the mercury switch |48 in this particular modification is substantially identical with those heretofore described, the principal distinction in this type of control residing in the nature of the spring restraint which is provided by the torsional energy stored in the spring strips |43 and |55 as they are twisted by the outward swinging movement of the switch |48 and counterbalance |54. The springs |43 and |55 also act to return the switch and counterbalance to the positions shown in Fig. l0.

It will be understood that any of the modica tions illustrated in Figs. 1, 3, 5 and l0 may be arranged to make associated electrical circuits by inverting the positions of the mercury switches and, also, that any of the indicated modifications may be horizontally disposed when used with a horizontal shaft. Further, any of the modifications may be connected to a rotary machine, generally speaking, for the purpose of controlling the speed of the particular machine, or for con` trolling the operation of other apparatus, or electrical circuits, which it is desired to control in reference to the speed of the machine with which the control is connected. Associate electrical circuits may be made" or "broken by this type of control with equal facility.

For example, where employed to control the speed of electric motors, the primary circuit of.

in either the primary circuit or the held coils, or

both, at any determined speed of rotation of the motor shaft. Because of its extreme sensitivity my control is particularly useful in the speed governing of alternating current motors, and for this purpose, it may be used to cut out the resistance in theA rotor circuit of such a motor which is started under load and which resistance it is desired to cut out after the motor attains speed; or an alternating current motor may be started as an induction motor and at some determined speed, the control may be arranged to change this motor over to a synchronous motor.

The primary advantage of my control is due to subjecting the mercuryswitch at all times to a spring tension and which enables the controlled apparatus to operate with an entire absence of any jerky or dampening action that would otherwise result in an extreme case of hunting. Any desired ranged of control may be freely exercised by suitably conditioning the spring tension, the initial radial distance of the axis of the mercury tube switch from the axis of the operating shaft, the initial inclination of the switch relative to this shaft, and by varying the character of the internal surface of the switch along which the mercury globule moves, i. e., by roughening or smoothing this surface, or otherwise conditioning the same so as to affect the movement of the mercury. The control is particularly useful in closely regulating the speed of an electric motor having a light armature because of the non-uniform acceleration and deceleration characteristic of this rotary part.

Where the conditions of operation require an inclination of the axis of the switch relative to the rotating shaft, an inclination of the switch tube of approximately 10 degrees has been found to be suitable, although this angle may be varied as desired. The switch tube may be moved outwardly until its inclination may vary from 6 degrees to 10 degrees and at this particular inclination one installation has been observed to make and break the associated electrical circuit at approximately 1200 times per minute, the free end of the switch tube oscillating approximately 51, of an inch to 11g of an inch at the indicated inclination. Under these conditions, the motor ran smoothly without hunting. The control is capable of being operated on alternating or direct current and in the case of alternating current, oscillograph tests have indicated that the mercury switch closes for a time duration of approximately six cycles and remains open for an equivalent period on an alternating current having a frequency of 60 cycles. Where direct current is employed, no spark quenching condensers or resistances are necessary in order to eliminate objectionable sparking within the switch during the rapid makes and breaks.

I claim:

l. A centrifugal control comprising a rotary part, a fluid flow switch mounted on the part to swing and reposition the fluid relative to at least one of the electrodes of the switch by the action of centrifugal force, and resilient means for yieldingly restraining the movement of the switch.

2. A centrifugal control comprising a rotary part, a fluid flow switch mounted on the part to swing and reposition the fluid relative to at least one of the electrodes of the switch by the action of centrifugal force, and means independent of centrifugal force for assisting in determining the position of the switch at any rotative speed of the part part, and a fluid flow switch bodily shiftable on the part under impulse of centrifugal force between positions making snd breaking an associated electric circuit, the switch being biased to one of the positions.

5. A centrifugal control comprising a rotary part, a fluid flow switch mounted on the part to swing and reposition the fluid relative to at least one of theelectrodes of the switch by the action of centrifugal force, means for adjusting the radial distance of the switch support from the axis of the part to vary the force effect on the switch, and resilient means for yieldingly restraining the movement of the switch.

6. A` centrifugal control comprising a rotary part, a fluid flow tube switch pivoted at one end on the part to rock and reposition the fluid relative to at least one of the electrodes of the switch by the action of centrifugal force, and a spring connecting the part and the free end of the switch.

7. A centrifugal control comprising a rotary' part, a fluid flow tube switch pivoted at one end on the part to rock and reposition the fluid relative to at least one of the electrodes of the switch by the action of centrifugal force, the switch being offset from the axis of the part, and a spring connecting the part and the free end of the switch.

8. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part to rock an end between inner and outer positions relative to the axis of the part and reposition the fluid relative to at least one of the electrodes of the switch, and resilient means for biasing the switch in the inner position.

9. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part to rock under the impulse of centrifugal force and thereby reposition the fluid relative to at least one of the electrodes of the switch, and a spring connecting the part and a free end of the switch, the axes of the spring and switch being substantially normal in all positions of the switch.

10. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part in offset relation to the axis of the shaft to rock under the impulse of centrifugal force and thereby reposition the fluid relative to at least one of the electrodes of the switch, a fixed counterbalance member mounted on the part in opposing, diametral relation to the switch, and a spring connecting the part and a free end of the switch.

11. A centrifugal control comprising a rotary beinglsubstantially normal in all positions of the switch.

12. A centrifugal control comprising in combination, a rotary part, a fluid ilow tube switch pivoted on the part in offset relation to the axis of the part to rock under the impulse of centrifugal force and thereby reposltion the fluid relative to at least one of the electrodes of the switch, a counterbalance member mounted on the part in opposing, diametral relation to the switch, a spring connecting the member and a free end of the switch, a pair of collector rings mounted on the part in insulated relation to each other and adapted for engagement by contacts forming a part of an electric circuit, and wires connecting the electrodes and rings, respectively.

13. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part in offset relation to the axis of the part to rock. under the impulse of centrifugal force and thereby reposition the fluid relative to at least one of the electrodes of the switch, a counterbalance member pivotally mounted on the part in opposing, diametral relation to the switch, and springs connecting the part and those ends of the switch and member, respectively, which tend to swing outwardly when the part is rotated.

14. A centrifugal control comprising in combination, a rotary part, a fluid flow tube switch pivoted on the part in offset relation to the axis of the part to rock under the impulse of centrifugal force and thereby reposition the fluid relative to at least one of the electrodes of the switch, a counter-balance member pivotally mounted on the part in opposing, diametral relation to the switch, springs connecting the part and those ends of the switch and member, respectively, which tend to swing outwardly when the part is rotated, and a pair of collector rings mounted on the part in insulated relation to each other and adapted for engagement by contacts forming a part of an electric circuit, the rings being electrically connected to the electrodes, respectively, one of the connections being through the member.

15. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part in offset relation to the axis of the part to rock under the impulse of centrifugal force and thereby reposition the fluid relative to at least one of the electrodes of the switch, a counterbalance member pivotally mounted on the part in opposing, diametral relation to the switch, and flat springs fastened to the part and switch and member, respectively, for resiliently restraining the movement of the switch.

16. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part in offset relation to the axis of the part to rock under the impulse of centrifugal force and thereby reposition the iluid relative to at least one of the electrodes of the switch, a counterbalance member pivotally mounted on the part in opposing, diametral relation to the switch, and a pair of U-shaped, flat spring elements located on opposite sides, respectively, of a line connecting the switch and member, each element having a pair of spring arms, the ends of the arms being spiraled and fastened to those ends of the switch and member, respectively which tend 'to swing outwardly when the part is rotated.

17. A centrifugal control comprising a rotary part, a fluid flow tube switch pivoted on the part in offset relation to the axis of the part to rock under the' impulse of centrifugal force and thereby reposition the fluid relative to at least one of the electrodes of the switch, a counterbalance member pivotally mounted on the part in opposing, diametral relation to the switch, a pair of U-shaped, nat spring elements located in opposite sides, respectively, of a line connecting the switch and member, each element having a pair of spring arms whose ends are spiraled and fastened to those ends of' the switch and member, respectively which tend to swing outwardly when the part is rotated, the switch spring arms being electrically connected to one of the switch electrodes, and a pair of collector rings insulated from each other mounted on the part, one ring being electrically connected to the other electrode and the other ring to the switch spring arms.

18. In a centrifugal control, the combination of a rotary part, a torsion spring carried by the part, and a fluid flow switch mounted on the spring to rock under the impulse of centrifugal force and thereby reposition the fluid-relative to at least one of the electrodes of the switch, the switch rocking against the torsion action of the spring.

19. In a centrifugal control, the combination of a rotary part, a flat spring flxedat its ends to the part, and a fluid flow switch secured at one end thereof to an intermediate portion of the spring and adapted to rock and twist the spring under the impulse of centrifugal force to thereby reposition the fluid relative to at least one of the electrodes of the switch.

20. In a centrifugal control, the combination of a rotary part, a pair of parallel, flat springs fixed at their respective ends to the part on opposite sides of the axis thereof, a fluid flow tube switch and a counterbalance member each supported at one end on an intermediate portion of the springs, respectively, the switch and member being adapted to rock under the impulse of centrifugal force and twist the springs, the rocking of the switch repositioning the fluid relative to at least one of the electrodes of the switch.

2l. In a centrifugal control, the combination of a rotary part, a pair of parallel, flat torsion springs fixed at their respective ends on and located on opposite sides of the axis of the part, a fluid flow tube switch supported at one end thereof on an intermediate portion of one of the springs, one of the switch electrodes being electrically connected to the switch supporting spring, a counterbalance member similarly supported on and electrically connected to the other spring, the switch and member being adapted to rock and twist the respective springs under the impulse of centrifugal force and the rocking of the switch repositioning the fluid relative to at least one of the electrodes of the switch, and a pair of collector rings mounted on the part in insulated relation to each other and adapted to be engaged by contacts forming a part of an electric circuit, the rings being electrically connected to the electrodes, respectively, one of the connections being through the member.

22. A centrifugal control comprising in combination, a rotary part, a mercury switch having a metallic end forming an electrode of the switch mounted onthe part to swing under the impulse of centrifugal force between positions making and breaking an associated electric circuit, resilient means for biasing the switch in the making position, and a metallic plate engageable with the metallic end at relatively low rotative speeds of' the part, the plate being connected in the cir- 7| cuit and the electric current being short-circuited through the plate until the rotary part attains a predetermined speed.

23. Means for controlling an electric circuit by the combined action oi centrifugal and centripetal forces comprising a rotary member, a shittabie device mounted on the member having a guiding surface and a pair oi electrodes forming a part o! a circuit, a mass o! current conducting fiuid for bridging the electrodes, the device and fluid being relatively shlftable by centrii'ugal force between positions making and breaking the circuit, and centripetal acting, resilient-means for restraining movement of the device.

24. A centrifugal switch comprising a member rotatable about a substantially vertical axis, a switch supporting means mounted thereon, and a uid ilow switch oi the tubular type mounted onsaidsupportingmeanaatieastaportionof said supporting means being movable with respecttosaidaxistoperntthealopeotsaid switch to change in responsa to centrifugal forces exerted thereon during notation of said basa.

25. A centrifugal switch comprising a member rotatable about a substantially vertical axis, a switch supporting means mounted thereon, and a fluid now switch mounted on said supporting means, said supporting means providing a yielding support to said switch which tends to restrain movement thereof along an arc away from said axis in opposition to the centrifugal forces ex erted on said switch during rotation o! said base, whereby the orientation of said switch with respect to the open and closed circuit positions thereof changes with speed o! rotation.

JOSEPH H. BTALIY.