US2280062A

US2280062A - Motorized mechanism

Info

Publication number: US2280062A
Application number: US308674A
Authority: US
Inventors: Robert S Craig
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1939-12-11
Filing date: 1939-12-11
Publication date: 1942-04-21
Anticipated expiration: 1959-04-21

Description

April 1942- R. s. CRAIG 2,280,062

MOTORI ZED MECHANISM Filed Dec. 11, 1959 2 Sheets-Sheet l 17 8\ l 8% c H I 55 1a s2 5 BI Q/ SI 85 Fig. 2 inventor Robe-r1- 5. Craig attorney VALVE STEM April 21, 1942.

R. S. CRAIG MOTORI ZED MECHANISM Filed Dec, 11, 1939 2 Sheets-Sheet 2 LI H8 ,IBZ

I80 mm jimxnfor "Robe-r1 ,8. Craig attoxneg Patented Apr. 21, 1942 MOTORIZED MECHANISM Robert S. Craig, Robbinsdale, Minnu assignor to Minneapolis Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application December 11, 1939, Serial No. 308,674

15 Claims.

The present invention is concerned with a motorized mechanism and more particularly one adapted to position a member movable between a safe first position and an active second position.

In many instances it is desirable to utilize a motor to position a device which is movable between a safe normal position and an active position. Thus one typical instance is that of a motorized valve controlling the flow of gas to a gas burner or the flow of other heating fluid to a heating apparatus. In-such a case, the valve is biased to closed position to insure the return 01' the valve to this position in the event of power failure. Another type of device of this character is a switch which is active only when it is closed. It is desirable in case of failure of the switch actuating mechanism for the switch to be moved to its circuit open or its safe position. The present invention is concerned with an arrangement wherein a motor positions such an element, the arrangement being particularly adaptable to the positioning of a valve.

An object of the present invention is to provide an arrangement wherein a motor moves a member to an active position wherein it is retained by a holding means separate from the motor, the transmission means between the motor and the positioned member being thereafter returned to the starting position so that upon release of the holding means, the member is free to return by suitable biasing means to its safe normal position.

Another object of the present invention is to provide, in an arrangement wherein a motor moves a member from a safe position to an active position and a holding means separate from the motor retains the member in its active position, transmission means between the motor and the member including a pair of separable links and means for separating the links after the member has been moved to active position, so that upon release of the holding means, the member is free to return by suitable biasing means to its safe normal position.

A further object of the present invention is to provide such an arrangement wherein the positioned member is a valve blasted to closed position.

A still further object of the invention is to provide an arrangement of the type mentioned in the previous objects wherein the motor is continuously operated until the transmission mechanism has been returned to its starting position.

A still further object of the invention is to provide an arrangement such as set forth abovein which the motor moves the positioning element to its active position where it is retained by the holding means and is thereupon deenergized and a biasing means is employed to return the transmission mechanism to its starting position.

A still further object of the present invention is to provide arrangements such as set forth above in which the holding means is electrically operated and is energized by the same source of power as the motor.

Other objects of the invention will be apparent from a consideration of the accompanying specification, claims and drawings of which:

Figure 1 is a schematic view of a preferred form of the invention,

Figure 2 is a schematic showing of a modification of one of the details of the arrangement of Figure 1, and

Figure 3 is a schematic view of a modified form of the invention.

Referring to the drawings for a more detailed understanding of the invention, the system is shown in Figure 1 in connection with the positioning of a valve. The valve is provided with a valve housing Ill having an inlet connection it and an outlet connection l2, Extending through the valve body is the usual transverse partition wall M which is apertured at it to provide a valve seat upon which the valve disc l6 seats. A spring l'l biases the valve disc 16 into engagement with its valve seat. Secured to the valve disc 16 is a valve stem IS.

A motor 20 is provided for moving the valve disc to its open position against the action of biasing spring ll. The motor 20 is shown as being of the induction type, having a rotor 2| and a field winding 22. The motor is connected to a reduction gear train generally indicated by the reference numeral 24. The gear at the low speed end of this gear train is designated by the numeral 25. Secured to gear 25 is a shaft 26 and axially aligned with shaft 26 is a second shaft 21. Secured to shafts 26 and 2? are

crank arms

28 and 29, the crank arms being connected by a rod 30. At the outer end of shaft 21 is a cam 3|. The motor 20 is so designed that upon energization of the field winding 22, the gear train is rotated in a direction such that gear 25 and shafts 26 and 21 are rotated in a clockwise direction. The cam 3i is shown in the position which it normally assumes when the valve is closed. The radius of the cam gradually increases in a counter-clockwise direction up to its high point 33. The cam surface immediately drops down to an arcuate portion extending from point 34 to point 35. This portion of the cam is of uniform radius for reasons to be pointed out hereinaiter. Projecting from the valve stem I8 is an arm 31 which engages the cam 3| and acts as a cam follower. It will be obvious that as the cam 3| is rotated in a clockwise direction from the position shown, the valve stem 3 will be raised until the cam follower 31 leaves the high point 33 whereupon the valve stem, unless otherwise restrained, is free to drop to the position shown in which position it remains throughout the rest of the revolution of the cam.

A spring 40 has one end secured to the rod 33. This spring 40 serves to oppose the action of the motor during the valve opening portion of the cycle and is effective to aid the motor after the high point 33 of the cam has left the cam follower 31.

It will be recalled that in the previous paragraph it was stated that the valve stem, after the cam follower 31 has passed over the high point of the cam, would be free to return to the position shown unless otherwise restrained. Suitable means are provided for normally holding the valve stem in valve open position when moved to this position. This means comprises an electromagnet 45 which cooperates with an armature 46 secured to the upper end of valve stem [8. The electromagnet 45 is provided with a winding 4? in the conventional manner. When the valve stem is moved to its uppermost position by the action of cam armature 46 is firmly moved into engagement with the electromagnet 45. Means are provided for energizing the electromagnet at this stage of the cycle so that the electromagnet is normally able to maintain the valve in open position as will be described latter. A thermostat 5|] is provided for controlling the operation of the valve. It is to be understood that any other control switch can be utilized. The thermostat as illustrated, comprises a bimetallic element M to which are secured

contact arms

52 and 53 which engage with

contacts

54 and 55, respectively. Contact arm 52 is less widely separated i'rom contact 54 than contact arm 53 is from contact 55. The bimetallic element 5i is so arranged that it moves the

contact arms

52 and 53 to the left upon a temperature fall as indicated by the legends on the drawing wherein the letter C represents cold and the letter H represents hot. Upon a fall in temperature, due to the unequal spacing of the contact arms from the contacts, contact arm 52 will engage contact 54 and upon further fall in temperature contact arm 53 will engage contact 55. Energization of the motor is further controlled by a maintaining switch generally designated by the numeral 58. This switch comprises a pair of

switch blades

59 and 60. The

blades

59 and 60 are secured to an insulated block 6|. The blade 60 has a curved upper portion 62 forming a cam surface cooperating with an arm 63 of insulating material secured to the valve stem l8. Upon upward movement of valve stem [8, the arm 53 engage the curved portion 62 of switch blade 60 and moves switch blade 60 into circuit making engagement with switch blade 59. I

Energization of the'motor is further controlled by a cycling switch mechanism including a pair of cooperating switch blades and H. The

switch blade 10 has an upwardly projecting portion 13 which cooperates with a pin 12 concentrically carried by the gear 25. When the gear portion H of switch blade 14 to hold switch blade 10 in its lowermost position. A pin 14 of insulating material carried by the valve stem l8 cooperates with the switch blade ll. When the valve stem is in valve closed position, as shown, the switch blade 1| is engaged by pin I4 and held in its lowermost position wherein it contacts switch blade 10 even when this switch blade is depressed by engagement of pin '12 with portion H thereof, as previously described. Both switch blades 10 and H are biased upwardly.

A step down transformer I! is provided for the purpose of supplying low voltage power for the operation of the motor and its control system. This transformer comprises a line voltage primary winding 18 and a low voltage secondary winding 19. The line voltage primary '18 is connected to line wires 80 and BI leading to a suitable source of power (not shown).

Operation of species of Figure 1 As previously indicated, the various elements are shown in the position occupied when the valve is closed. This is the position which they assume when the temperature to which thermostat is subjected is at or above the desired value. Upon a drop in temperature, switch blade 52 is first moved into engagement with contact 54. This, by itself, results in the establishment of no energizing circuits. Upon a further drop in temperature, switch blade 53 is moved into engagement with contact and. the following energizing circuit i established to the field winding 22: from the upper terminal of secondary '19 through con-- ductor 83, contact 54, contact arm 52, contact arm 53, contact 55,

conductors

84 and 85, field f winding 22, conductor 86, switch blades 10 and 3i results in the valve stem being moved upward- 25 is in the position shown, a pin 12 engages the ly towards valve open position. While the upward movement of valve stem it permits switch arms M to move upwardly, this does not result in the circuit being interrupted since the initial movement of gear 25 also moves pin 12 away from the upwardly projecting portion 13 of switch blade l5 so as to allow this switch. blade to follow switch blade 1 l After an initial upward movement of valve stem it has taken place, the arm 63 engages the inclined portion 62 of switch blade 60 to move

switch blades

59 and 60 into contact making engagement. The result is that the following maintaining circuit is established to field winding 22: from the upper terminal of secondary 79 through conductor 83, contact 54, contact arm 52, bimetallic element 5|, conductor 9|,

switch blades

60 and 59, conductors 92, 93, and field winding 22, conductor 86, switch blades 10 and H and

conductors

81 and 88 to the other terminal of secondary '19. It will be noted that this new circuit to field winding 22 is independent of contact arm 53 and contact 55. It is this contact arm and contact which are the last to be engaged and are consequently the first to be disengaged. Thus it is assured that upon initial engagement of both pairs of contacts the motor will continue to remain energized even though one set of contacts is immediately thereafter separated. In this way, an appreciable temperature differential is required between the successive operation of the device so that chattering or excessively frequent operation is avoided.

Upon engagement of both contact arins 52 and 53 with their

respective contacts

54 and 55, an energizing circuit is established to the winding 41 of electromagnet 45. As soon as

switch blades

50 and 53 are moved into engagement, 9. maintaining circuit is established to the winding 41. Since this maintaining circuit is established before it is necessary for the electromagnet to become active, it is only necessary to consider this maintaining circuit which is as follows: from the upper terminal of secondary 13 through conductor 33, contact 54, contact arm 52, bimetallic element conductor 3|,

switch blades

30 and 59, conductors 32 and 95, winding 41, and conductors 36 and 83 to the other terminal of secondary 19. Since winding 41 is energized independently of contact 55 during the initial movement of the valve. it is assured that when armature 46 is moved into engagement with electromagnet 45,

the electromagnet will be effective to retain the armature in engagement therewith. There is no positive connection between the cam 3| and the pin 31 so that as soon as the high point 33 of cam 3| passes the pin 31 the valve stem is under the sole control of magnet 45. The motor continues to rotate until the gear train returns to the position shown at which time pin I2 engages the upwardly projecting portion I3 of switch blade I0 to move this blade to its lowermost position. Since switch blade II has moved upwardly by reason of the upward movement of pin I4 and since this pin is still in this uppermost position by reason of the valve stem being held upwardly by the electromagnet 45, switch blades and II will no longer be in engagement when switch blade 10 is moved to its lowermost position. The result is that the switch blades I0 and II are separated at this point to terminate energization of the field winding 22. It will be seen that the cam 3| and the pin 31 constitute a pair of separable links, and that after the high point 33 of cam 3| passes pin 31, the links are separated in such a manner that the valve is free to return to its closed position upon release by the magnet 45.

The valve disc I5 is held in open position as long as electromagnet remains energized. This will continue as long as contact arm 52 of the thermostat is in engagement with contact 54. Switch 58, connected in parallel with contacts 53-55, is closed. Therefore separation of

contacts

53 and 55 does not affect the energization of electromagnet 45. As soon as the contact arm 52 separates from contact 54, the winding 41 of electromagnet 45 will be deenergized so as to permit the biasing spring I1 to move the valve abruptly to closed position.

The maintaining circuit previously described, including contacts 5254 and switch 53, prevents the opening of contacts 53-55 from causing immediate deenergization of solenoid 45 and consequent closure of valve I6. An appreciable differential is thereby provided between the temperature at which contacts 5355 close, causing the valve to open, and the temperature at which contacts 52-54 open, causing the valve to close. This temperature differential prevents erratic operation of the valve because of chattering thermostat contacts either due to vibration, or from other causes.

gasburner in accordance with the need for burner operation as indicated by the temperature to which the thermostat is responsive. In this field, it is essential that if there is a power failure, the valve will be moved to closed position. It will readily be seen that where the normal cycle is completed, the valve is under the sole control of the electromagnet and obviously any power failure results in immediate closure of valve disc I6. liIt is always possible, though unlikely, that such a power failure might occur during the opening cycle and in such a case, if some other means than motor 20 were not provided for actuating the gear train 24, the cam 3| might be left in intermediate position wherein the valve would be held in a partially open position. The spring 40 is provided for guarding against such a contingency. The spring 40, acting through the crank arm formed of crank

arms

28 and 29 and rod 30 tends to bias the gear 25 and cam 3| in a counter-clockwise direction during the initial portion of the operating cycle. As the valve approaches open position the moment arm exerted by spring 40 is increased due to the fact that the crank

arms

28 and 29 tend to approach a position more nearly transverse to the direction of pull of spring 40. Before the crank arms 28 and 23 have revolved to the dead center position, the high point 33 of cam 3| has moved from underneath the pin 31 so that even if a power failure resulted in the cam 3| remaining in this position, the valve could completely close. As pointed out previously, the radius of the cam surface is constant from point 34 to point 35 so that when the cam is in any position wherein the cam follower 31 would engage this portion of the cam surface, the valve can move to completely closed position.

It will be seen that I have provided an arrangement wherein a motor is employed to drive a valve to open position, leave it under the control of a holding means and then to return the gear train and the various other elements of the connecting mechanism to the starting position. In this way it is assured that the valve will always be free to close upon termination of the holding effect of the holding means. It will further be noted that I have provided means whereby the valve may be safely closed in the event of a power failure at any time during its operating cycle.

M odification of Figure 2 In Figure 2, there is illustrated a slightly modified form of holding means which may be employed with the valve of Figure 1. In the arrangement of this figure, an electromagnetic latch is employed in lieu of a plain electromagnet. Such a latch has the advantage that it is capable of holding a considerably greater load for the same number of ampere-turns in the electromagnet. The valve stem in this figure is designated by the numeral IOI. It will be understood that this valve stem is identical in function and arrangement to the valve stem I8 of Figure 1 with the sole exception that instead of an armature being secured at the upper end thereof, the valve stem is provided with a notch I02. A pivoted latch I03 has a nose portion I04 which is adapted to extend into the notch I02 and retain the valve stem against downward movement. Secured to the horizontal arm of the pivoted latch I03 is an armature I04 which cooperates with an electromagnet I05. The latch I03 is pivoted about a pivot I06 and is biased clockwise by a spring I00. The electromagnet I when energized overcomes the effect of spring I08 to maintain the latch in its latching position. As soon as the electromagnet s deenergized however the spring I08 is effective to rotate the latch I03 in a clockwise direction to move the nose I04 out of the notch I02 and permit downward movement of the valve stem IOI. It will be understood that the electromagnet I05 is connected into the circuit in the same manner as magnet 45 of Figure 1 and that the operation of this system is in all other respects identical to that of Figure 1.

Species of Figu 3 In Figure 3 I have shown a modified form of my invention. In the arrangement of this figure, a motor is effective to move the valve in cooperative relation with a holding means as in the species of Figure 1. Unlike the previous species, however, a biasing spring is effective to return the motor and its connecting mechanism to the starting position.

Referring to the specific structure of Figure 3 the valve is generally designated by the reference numeral II5, this valve is provided with a valve stem H6. The valve is similar in construction to the valve of Figure 1 so that upward movement of valve stem II6 causes the valve to be moved to open position and downward movement of stem II6 causes the valve to be closed.

A motor I is employed for positioning the valve. This motor comprises a rotor IN and a field winding I22. The rotor IN is connected through a reduction gear train comprising a gear I26 at the low speed of the gear train. A pin I21 projects, outwardly from the gear I26 and is adapted to cooperate with a hook I 28. The hook I20 is pivotally secured. at I29 to a lever I30 pivotally supported by a pivot pin I32. The lever 930 extends through an elongated eye portion I34 at the upper end of valve stem H6. The motor I20 is so designed as to cause clockwise movement of gear I26 upon energization of the motor. Upon such clockwise movement, the pin I21 engages the hook I28 and rotates the lever I30 in a clockwise direction. This results in the lever I30 moving valve stem II6 upwardly.

A coil spring I33 is associated with the lever I30 for returning the transmission mechanism to its starting position. The spring I33 is positioned about the pivot pin I32. One arm of spring I33 engages a pin I38 secured to lever I30 and the other arm enga es a fixed pin I39. The

result is that spring I33 exerts a force tending to rotate lever I30 in a counter-clockwise direction.

An electromagnet I40 is provided for retaining the valve stem in valve open position. This electromagnet comprises a core MI and a winding I42. Cooperating with the core MI is an armature I44 carried by a lever I 45 pivoted about a fixed pivot pin I46. A spring I biases the lever I45 away from the electromagnet. Also secured to the pivot pin I46 is a member I41. A spring I48 is connected between the outer ends of member I41 and lever I45 so as to tend to rotate member I41 clockwise with respect to lever I45. Such clockwise movement is limited by a stop pin I49 carried by lever I45. Member I41 is thus connected to lever I 45 through a strain release connection whereby the member I41 unless otherwise restrained tends to rotate with lever I45. Carried at the lower end of member I41 is a projection I52 which is adapted to enter a notch I54 in the valve stem II8 when the stem is raised to substantially valve open position.

Secured to the left hand end of lever I45 is a switch blade I58 which is adapted to cooperate with a fixed contact I51. The switch blade I56 and contact I51 are employed for establishing a maintaining circuit to the apparatus as will be presently described.

An over center snap action switch is employed for controlling the energization of the motor. This switch comprises a switch arm I60 and an arm I6I both pivoted about a pivot point I62. Connecting the two members I60 and I6I is a spring I64. The switch arm I60 is adapted to engage a contact I65. The arm I6I is positioned by two arms I61 and I68 projecting from valve stem II6. Asthevalve stem is moved upwardly, the arm I61 is effective to rotate arm I6I in a clockwise direction until'the arm I6I is aligned with arm I60. This portion of the movement is resisted by spring I64. As soon as arm I6I is moved farther however, it is past the "dead center position so that spring I64 is immediately effective to continue the clockwise movement of arm I6I until it engages the upper arm I68 whereupon arm I60 is abruptly moved upwardly until it engages a stop pin I69. The switch arm H60 is thus separated from contact I65 with a snap action. The projecting arms I61- and I68 are so positioned that this snap separation of switch blade I60 of contact I65 takes place just as the valve reaches open position and at the time when notch I54 is adjacent the projection I52 of member I41.

A thermostat I1I controls the operation of the valve. This thermostat is equivalent in function and in structure to thermostat 50 of the species of Figure 1. The thermostat comprises a bimetallic element I 12 to which are secured contact arms I13 and I14. The bimetallic element is effective upon a temperature drop to move contact arms I13 and I14'to the left and upon a temperature rise to the right. Contact arms I13 and I14 are adapted to engage fixed contacts I15 and I16. The spacings of the contact arms I13 and I14 from contacts I15 and I16 are such that contact arm I13 is first engaged with contact I15 and contact arm I14 is then engaged with contact I16.

A step down transformer I is employed for supplying low voltage power to the motor and its control system. This transformer comprises a line voltage primary I8I and a low voltage secondary I82. The line voltage primary I8I is connected to a suitable source of power (not shown).

Operation of Figure 3 species The various elements are shown in the position they assume when the temperature is at or above the desired value. Under these conditions the valve is in its closed position. Upon a temperature drop, contact arm I13 is moved into engagement with contact I15 and upon a further drop, contact arm I14 is moved into engagement with contact I 16. No energizing circuit is established until contact arm I14 engages contact I16. As soon as this happens, the following energizing circuit is established to the field winding I22: from the right hand terminal of secondary I82 through conductor I83, contact I 15, contact arm I13, contact arm I14, contact I16, conductors I85 and I86, field winding I22, conductor I81, contact arm I60, contact I65 and conductors I88 and I84 to the other terminal of secondary I82. The establishment of this circuit causes energiaztion of field winding I22 and rotation 01- the gear train in such a direction that gear I is moved in a clockwise direction. As previously explained, this causes the pin I21 to engage with hook I28 and rotate lever I in a clockwise direction. This movement of lever I30 results in valve stem II6 being raised towards valve open position.

At the same time that the field winding I22 is first energized, a circuit is established to the winding I42 oi the electromagnet I as follows: from the right hand terminal of secondary I80 through conductor I83, contact I15, contact arms I13 and I14, contact I16, conductors I85, I89, and I90, magnet winding I42 and conductors I9I and I84 to the other terminal of secondary I82. The energization of electromagnet I40 results in the lever I being rotated in a clockwise direction. While movement of member I41 is impeded by reason of the fact that the projection engages the right hand edge of valve II 6 and is unable to enter the notch I54,

movement of lever I45 is still possible due to the strain release connection between members I45 and I41. In other words, the lever I45 is moved upwardly until the armature I44 engages the core I against the action of spring I and spring I48 which urges the projection I52 against the edge of valve stem II6. Movement of lever I45 in the manner described results in the movement of switch blade I56 into engagement with contact I51. As soon as such engagement takes place, a maintaining circuit is established to the field winding as follows: from the right hand terminal of secondary I82 through conductor I83, contact I15, contact arm I13, bimetallic element I12, conductor I94, contact I51, switch blade I56, conductors I95, I89, and I86, field winding I22, conductor I81, switch arm I60, contact I65, and conductors I88 and I84 to the other terminal of the secondary I82. At the same time a maintaining circuit is established to the magnet I42 as follows: from the right hand terminal of secondary I82 through conductor I83, contact I15, contact arm I13, bimetallic element I12, conductor I94, contact I51, contact arm I56, conductors I95 and I90, magnet winding I42 and conductors I9I and I84 to the other terminal of secondary I82.

The establishment of the two maintaining circuits just traced results in the energization of the motor and of the electromagnet being independent of the engagement of contact arm I14 with contact arm I16. The advantage of this feature is the same as described in connection with Figure 1. In other words, a differential is introduced into the operation to prevent chattering or excessively frequent operations of the valve.

As the valve approaches open position, the notch I54 in the valve stem II6 comes adjacent the projection I52 of member I41. This member is forced into the notch by reason of the action of spring I48 which, as previously explained, has been placed under tension by movement of the lever I45 into the position in which the armature is engaged with the electromagnet. Immediately after the projection I52 has entered the notch I54, the arm I6I is moved beyond center with respect to arm I so as to cause these two arms to snap over center'thereby abruptly separating switch arm I 60 from contact I65. The separation of these two contacts results in the interruption of both of the circuits to field winding I22 previously traced. The motor is thus completely deenergized so that biasing spring I 33 is now free to rotate lever I30 in a counter-clockwise direction. The biasing spring I33 is of such size that it is able to rotate the gear train I25 and the motor rotor I2I in the reverse direction back to their original positions. Such return movement of lever I30 does not cause the valve to close due to the fact that the valve stem is now latched in open position by the projection I52 of member I41 which extends into the notch I54. The movement of lever I30 downwardly in a counter-clockwise direction, in spite of the valve stem II6 remaining in valve open position, is possible because of the elongated eye portion I34 which provides the connection between the lever I30 and the valve stem II6.

It will be seen that the lever I30 and the elongated eye portion I34 of stem IIB constitute a pair of separable links, and that after lever I30 is returned to the bottom of the eye portion I34 by the action of spring I33, the links are separated in such a manner that the valve is free to return to its closed position upon release of projection I52 by electromagnet I42.

The valve remains in its open position until contact arm I13 has separated from contact I15. When this happens, the electromagnet I40 is deenergized so that the .lever I45 moves to the position shown in the drawings in which the projection I52 is no longer in the notch I54. This movement of lever I45 is caused by not only the efiect of gravity on the lever but also by the biasing spring I50.

As with the species of Figures 1 and 2, it is assured that the valve will always return to closed position in the event of power failure regardless of when such power failure occurs. Obviously such a power failure will result in the release of armature I44 so that the lever I45 is ineffective to retain the valve in open position. If the power failure occurs before the projection I52 has entered the notch I54, then the valve is being held in open position only by the action of motor I20. Upon such power failure at this time, the spring I33 is efiective to return the transmission mechanism to its initial position and the valve returns to its closed position by its own biasing means.

Whenever the valve stem returns to closed position, switch arm I60 is snapped back into engagement with contact I through the action of the projecting arm I68. Switch blade I60 is thus again positioned in engagement with contact I65 so as to make possible the reenergization of the motor for the next operating cycle.

While the invention has been described in connection with valve operators since this is the application for which it is most adapted, it is to be understood that the invention is applicable to the positioning of other devices movable between a safe position to which the device is biased and a further active position. In general, while I have shown certain specific embodiments of my invention, it is to be understood that this is for purposes of illustration only and that the invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, electrically operated holding means for retaining said member in said second position when an element associated with said member is moved into cooperative relation therewith, motor means including a uni-directional electric motor and a biasing means, means for transmitting motion from said motor means to said member, a main control switch, switching means operable by said motor means and said member, a source of power, means controlled by said main control switch for connecting said source of power to said electrically operated holding means, and means controlled by said switching means operative to control the energization of said electric motor in such a manner that said motor is effective to move said element into cooperative relation with said holding means and subsequently to drive said motion transmitting means back to its original position, said biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of said motor it is efiective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position,

2. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, electrically operated holding means for retaining said member in said second position when an element associated with said member is moved into cooperative relation therewith, motor means including an electric motor and a biasing means, means for transmitting motion from said motor means to said member, a main control switch, a normally closed cycling switch, means for opening said switch when said member is in said second position and said transmission means is returned to said original position, a source of power, means controlled by said main control switch for connecting said source of power to said electrically operated holding means, and a circuit for said motor including said cycling switch operative to cause the energization of said rotary electric motor by said source of power until said element is moved into cooperative relation with said holding means and said motion transmitting means is returned to its original position, said biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of said motor it is effective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position.

3. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, electromagnetic holding means for retaining said member in said second position when an armature associated with said member is moved into cooperative relation therewith, a rotary electric motor; means for transmitting motion from said motor to said member, a connection between said motion transmitting means and said member permitting movement of said motion transmitting means back to its original position without affecting the position of said member when said member is in said second position, a 'main control switch, switching means operable in accordance with the position of said member, a source of power, means controlled by said main control switch for connecting said source of power to said tor by said source of power in such a manner that said armature is moved into cooperative relation with said holding means and said motion transmitting means is then returned to its original position.

4. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, electrically operated holding means for retaining said member in said second position when an element associated with said member is moved into cooperative relation therewith, motor means including a rotary electric motor and a biasing means, means for transmitting motion from said motor means to said member, a connection between saidmotion transmitting means and said member permitting movement of said motion transmitting means back to its original position without affecting the position of said member when saidmember is in said second position, a main control switch, switching means operable in accordance with the position of said member, a source of power, means controlled by said main control switch for connecting said source of power to said electrically operated holding means, and means controlled by both said main control switch and said switching means operative upon closure of said main control switch to control the energization of said rotary electric motor by said source of power in such a manner that said element is moved into cooperative relation with said holding means and said motion transmitting means is then returned to its original position, said biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of said motor it is effective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position.

5. In combination, a, member movable between a safe first position and an active second position, said member being biased to said safe first position, electrically operated holding means for retaining said member in said second position when an element associated with said member is moved into cooperative relation therewith, motor means including a rotary electric motor and a biasing means, means for transmitting motion from said motor means to said member, a connection between said motion transmitting means and said member permitting movement of said motion transmitting means back to its original position without affecting the position of said member when said member is in said second position, a main control switch, switching means operable by said motor means and said member, a source of power, means controlled by said main control switch for connecting said source of power to said electrically operated holding means, and means controlled by both said main control switch and said switching means operative upon closure of said main control switch to cause said motor to be energized until it has moved said element into cooperative relationship with said holding means and has then driven said motion transmitting mechanism back to its original position, said biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of said motor it is effective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position.

6. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, electrically operated holding means for retaining said member in said second position when an element associated with said member is moved into cooperative relation therewith, motor means including a rotary electric motor and a biasing means, means for transmitting motion from said motor means to said member, a connection between said motion transmitting means and said member permitting movement of said motion transmitting means back to its original position without affecting the position of said member when said member is in said second position,'a main control switch, switching means operated by said member, a source of power, means controlled by said main control switch for connecting said source of power to said electrically operated holding means, and means controlled by both said main control switch and said switching means operative upon closure of said main control switch to cause said motor to be energized until it has moved said element into cooperative relationship with said holding means and to deenergize said motor immediately thereafter, said biasing means being effective upon deenergization of said motor at any time to return said motion transmitting means to its starting position.

7. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, electrically operated holding means for retaining said member in said second position when an element associated with said member is 2 moved into cooperative relation therewith, motor means including an electric motor and a biasing means, transmission means between said motor means and said member comprising a rotary cam driven by said motor and a cam follower associated with said member, said cam having a substantial portion of its periphery of uniform radius and the remainder of gradually increasing radius, said uniform radius being of such magnitude that when the cam follower is in engagement with that portion of the cam, said member is maintained in said safe position by its bias, a main control switch, switching means operable by said movable member and said motor means, a source of power, means controlled by said main control switch for connecting said source of power to said electrically operated holding means, and means controlled by said switching means operative to control the energization of said electric motor by said source of power in such a manner that said element is moved into cooperative relation with said holding means and said transmission means is then returned to its original position, said biasing means being so connected to said transmission means that in the event of power failure during the movement of said motor it is effective at all times to insure that said cam is moved to a position wherein said cam follower engages the portion of said cam surface of uniform radius so that said member is moved by its bias to said first position.

8. In combination, a member movable between a safe first position and an active second position, said member being biased to said safe first position, a latch for retaining said member in said second position when an element associated with said member is moved into cooperative relation therewith, an electromagnet for moving said latch to its operative position, a switch positioned by said electromagnet, a

strain release connection between said latch and said electromagnet so that upon energization thereof said electromagnet can assume its energized position and position said switch even though said element is not in cooperative relation with said latch. an electric motor for moving said member to said second position, a main control switch, switching means operable by said movable member, a source of power, means controlled by said main control switch for connecting said source of power to said electromagnet to cause said electromagnet to bias said latch ta its operative-position and to position its associated switch, and means controlled by said electromagnet switch and said switching means for causing the energization of the motor to move' said element into cooperative relation with said latch and thereafter deenergizing said motor.

9. In combination, a member biased to a first position, a latch'for retaining said member in a second position when a shoulder portion oi said member is moved adjacent said latch, an electromagnet for moving said latch to its operative position, a switch positioned by said electromagnet, a strain release connection between said latch and said electromagnet so that upon energization thereof said electromagnet can assume its energized position and position said switch even though said shoulder is not adjacent said latch, an electric motor for moving said member to said second position, a main control means under the control of said main control switch for energizing said electromagnet to cause said electromagnet to bias said latch to its operative position and to position its associated switch, switching means operated by said member, and means controlled by both said electromagnet switch and said switching means operative as a result of closure of said main control switch to cause energization of the motor until said shoulder portion is engaged by said latch and thereafter to deenergize said motor.

10. In combination, a member movable between a first position and a second position, means biasing said member to said first position, electrically operated means for holding said member in said second position against the action of said biasing means, motor means including an electric motor and a second biasing means, means for transmitting motion from said motor means to said member, a connection between said motion transmitting means and said member permitting movement of said transmitting means back to a position corresponding with the first position of said member while said member re mains in its second position, a first switch, a second switch operable in accordance with the position of said member, an energizing circuit for said holding means. an energizing circuit for said motor, and means including said circuits controlled by said switches and operative upon closure of said first switch to cause said motor means to move said transmitting means and hence said member from first to second position and then to return only said transmitting means to its position corresponding to the first position of said member said second biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of said motor it is effective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position.

11. In combination, a member movable between a first position and a second position,

means biasing said member to said first position, electrically operated means for holding said member in said second position against the action of said biasing means, motor means including an electric motor and a second biasing means, means for transmitting motion from said motor means to said member, a connection between said motion transmitting means and said member permitting movement of said transmitting means back to a position corresponding with the first position of said member while said member remains in its second position, a first switch, a second switch operable in accordance with the relative positions of said transmitting means and said member, an energizing circuit for said holding means, an energizing circuit for said motor, and means including said circuits, controlled by said switches and operative upon closure of said first switch to cause said motor means to move said transmitting means and hence said member from first position to second position and then to return only said transmitting means to its position corresponding to the first position of said member said second biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of -said motor it is efiective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position.

12. In combination, a member movable between a, first position and a second position, means biasing said member to said first position, electrically operated means for holding said member in said second position against the action of said biasing means, motor means including an electric motor and a second biasing means, means for transmitting motion from said motor means to said member, a connection between said motion transmitting means and said member permitting movement of said transmitting means back to a position corresponding with the first position of said member while said member remains in its second position, a first switch, a second switch operated by said member, an energizing circuit for said holding means, an energizing circuit for said motor, and means including said circuits controlled by said switches and operative upon closure of said first switch to cause said motor means to move said transmitting means and hence said member from first position to second position and then to return only said transmitting means to its position corresponding to the first position of said member said second biasing means being so connected to said motion transmitting means that in the event of power failure during the movement of said motor it is effective to move said motion transmitting means to a position wherein said member is free to move by its bias to said first position.

13. In combination, a member biased to a first inactive position, holding means for retaining said member in a second active position when an element associated with said member is moved into cooperative relationship therewith, a rotary electric motor, means for transmitting motion between said motor and said member, a main control switch, a second switch operable in accordance with the position of said member, and a single energizing circuit including said motor controlled by said switches and operative upon closure of said main control switch to cause movement of said member from first to second position, thereby moving said element into cooperative relationship with said holding means, and then to cause movement of said motiontransmitting means to a position corresponding to the first position of said member.

14. In combination, a member biased to a first position, an electromagnet for retaining said member in a second position when an armature connected to and movable with said member is moved into engagement with said eloctromagnet. an electric motor, means for transmitting motion from said motor to said member, a connection between said transmitting means and said member permitting movement of said transmitting means back to its original position while said member remains in its second position, a main control switch, a second switch operable in accordance with the position of said member, and a single energizing circuit including said motor controlled by said switches and operative upon closure of said main control switch to cause movement of said member from first to second position, thereby moving said armature into engagement with said electromagnet, and then to cause movement of said motion-transmitting means to a position corresponding to the first position of said member.

15. In combination, a member biased to a first position, electically operated holding means for retaining said member in a second position when an element associated with said member is moved into cooperative relationship with said holding means, an electric motor, means for transmitting motion from said motor to said member, a connection between said transmitting means andv said chamber permitting movement of said transmitting means back to its original position while said member remains in its second position, a main control switch, a second switch operable in accordance with the position of said member, and a single energizing circuit including said motor controlled by said switches and operative upon closure of said main control switch to cause movement of said member from first to second position, thereby moving said element into 00-- operative relationship with said holding means, and then to cause movement of said motiontransmitting means to a position corresponding to the first position of said member.

ROBERT S. CRAIG.