VALVE ACTUATOR
This invention relates generally to an actuator for a rotary type valve which, for example, may be a throttle valve in which the valve member is a disc generally capable of rotating a quarter turn between open and closed positions. More particularly, it relates to improvements in rotary valve actuators in which the valve member is moved between open and closed positions by means of a reversible electric motor. A rotary valve actuator of the type contemplated by this invention comprises a housing adapted to be mounted on the valve, a drive system including a worm gear mounted for rotation in the housing and adapted to be releasably connected to the rod of the valve. valve, when the housing is mounted on the valve, in order to impart rotation thereto, a reversible electric motor in the housing having an output shaft, a worm shaft mounted for rotation and limited reciprocation within the housing, and means that connect the motor arrow to the worm arrow to rotate the worm arrow and connect the worm arrow to the worm gear to rotate the worm gear and thus the valve rod in opposite rotational directions to open and close the valve in response to reverse motor operation. In most of the foregoing actions of this type, the electric motor is adapted to be deactivated in case of excessive torque on the drive system when, for example, the valve member encounters an obstruction. For this purpose, it has been proposed to mount a worm for rotation with the worm arrow and a cam on the worm arrow adjacent to the worm to link sensors in switches that lead to the motor, when the impulse system finds excessive torsion, to deactivate the motor. More particularly, the worm and the cam are arranged in neutral positions between compressed springs, in response to the increased resistance to the rotation of the worm gear, to allow a surface on the cam to move longitudinally in connection with a sensor operating a switch to stop the motor. Preferably, the motor shaft and the worm shaft are connected by means of a pinion gear capable of rotating with the worm shaft and a straight gear on the motor shaft that maintains a connection with the first pinion gear despite limited reciprocation of the worm arrow. Also, the worm arrow is received for reciprocation and rotation within spaced bearings in spaced apart walls of the housing, and the spring means are compressed between the walls and ends of the assembly. In the past, this movement of the worm arrow, and therefore of the torsion cam so as to drive the sensors or switches, has required complicated gearing between them and the arrow. Furthermore, the cam and the sensors have been of complex construction and difficult to install as well as to adjust or modify for different torsion limits. Also, mechanisms of this type to deactivate the electric motor have not been supplied as optional equipment, that is, the actuator has been provided with or without the torsion limiting mechanism. Furthermore, access to such prior mechanisms for adjustment purposes has been slow and difficult. It is an object of the invention to provide an actuator having such a torsion limiting device, where the worm gear and the worm shaft are connected and installed easily and quickly and, as will be described below, are of such construction to cooperate with a manual overdrive system that includes a manual wheel selectively engageable with the arrow to operate the valve upon deactivation of the engine. An additional objective is to provide such an actuator, in which at least the sensors or switches are easily installed as optional equipment, easily accessible for replacement or repair, of simple and inexpensive construction, and easily adjusted to deactivate the motor at the desired levels of torsion. According to a novel aspect of the invention, the means engageable by the torsion cam to deactivate the motor in response to excessive torsion comprise a pair of keys, each mounted pivotally in the housing and having a finger that assumes an opposite position to a lea surface, and a pair of switches, each mounted in the housing in a position to be linked by one of the fingers in order to deactivate the motor, as it moves along the cam surface upon longitudinal movement of the worm arrow in opposite longitudinal directions in response to torque of sufficient magnitude to overcome a predetermined force and thus move the cam to one side of its neutral position. Preferably, a lever is mounted on each of the keys to link one of the switches, when the key is thus moved, the keys are aligned axially and the sensors and arms are aligned on opposite sides of the keys. As shown, means are provided to easily and quickly adjust the location of the position of each key relative to the cam surface opposite its finger, and thus the torque at which the motor is deactivated. In the illustrated and preferred embodiment of the invention, the housing includes a base on which the motor and the drive system are arranged, including the torsion cam, and a switch plate is releasably connected to the base of the motor. accommodation to cover the impulse system. More particularly, the keys and switches of the torsion limiting mechanism are mounted in a clamp releasably connected to the wall to hold the levers for extension through a hole in the switch plate to a position for attachment by the torsion cam. Manual overdrive assemblies for previous drives of this type have been complicated and expensive construction and, in some cases, have required a complex gear between the manual wheel and the worm arrow to prevent rotation of the manual wheel while the electric motor is activated. It is therefore another objective of this invention to provide a manual overdrive that includes a unique arrangement for linking to the worm arrow of the impulse system at any rotation position of the latter, but detachable from it to automatically deactivate the motor at move the manual overdrive to position linked to the worm arrow. In this way, the manual overdrive assembly includes a manual wheel having a manual overdrive arrow mounted in the housing in alignment with the worm arrow for rotation and reciprocation therebetween between first and second longitudinal positions, means connecting the manual overdrive arrow to the worm arrow in order to rotate the arrow, when the rod is in said first position, and to disconnect the rod from the worm arrow, when it is in the second position, and means that respond automatically to the shift of the manual overdrive arrow to its first position to deactivate the motor. More particularly, the manual overdrive arrow and the worm arrow are of such construction that they remain disconnected, despite the limited reciprocation of the worm arrow in response to the predetermined torque. Preferably, the base of the housing has a cavity opening internal to one end, and the manual overdrive assembly further comprises a liner in which the manual overdrive arrow is carried and removably mounted within the cavity, the liner installation in the cavity serving to pre-compress the springs and in this way move the worm gear and the cam to its neutral position. According to another novel aspect of the invention, the inner end of the manual overdrive arrow includes a sleeve having longitudinal slots, and the adjacent end of the worm arrow has at least one protrusion to fit within a slot, when the manual wheel and the manual overdrive arrow are moved to a position, and to slide out of the slot when moving to another position, so as to release the worm arrow for rotation, and means are provided to releasably hold the manual overdrive arrow in each of its positions. According to still another novel aspect of the manual overdrive assembly, a sensor of a switch is mounted in the housing, and a rod mounted on the switch for operation through holes in the switch plate and the liner, as well as in the sleeve at the outer end of the manual overdrive arrow to arrange the inner end of the rod in the arrow path, when moving to the other position, to cause the switch to deactivate the motor, and disengaged with it, when the arrow of Manual overdrive is moved to its first mentioned position, to allow the motor to be activated. It has also been proposed to automatically activate and deactivate the electric motor of such an actuator by means of limit switches which are linked by cams capable of rotating in response to the rotation of the valve stem between open and closed positions of the valve. It is often necessary to adjust the positions of the cams in order to adjust the open and closed positions of the valve. US Patent No. 5,305,781, assigned to the assignee hereof, shows an arrangement of cams capable of rotating with the valve stem for linking with switches to indicate the position of the valve at a remote location. The cams can be adjusted to different rotation positions by knobs that are easily accessible for manual manipulation at one end of the cams. A further object of this invention is to adapt a similar arrangement of cams for use in adjusting the open and closed positions of the valve in which the motor can be deactivated and, more particularly, an actuator that allows access to the cams for adjustment merely upon removal of a cover adapted to be installed on the base of the actuator housing. Thus, in accordance with still a further novel aspect of the invention, first and second axially spaced plates surround and are releasably fixed to an arrow capable of rotating with the valve rod, a first ring closely surrounds the first plate for rotation with with respect to it and has a circle of teeth formed around its interior, and a second ring closely surrounds the second plate for rotation with respect to it and has a circle of teeth formed around its interior. More particularly, each ring has an external cam surface around it, eccentric to its axis of rotation, and first and second switches are mounted on the switch plate in the housing in position to be linked and activated by the cam surfaces in the first and second rings, respectively, during rotation of the arrow so as to stop the engine when the rod reaches the open or closed position. The positions of the cams, and thus the starting and stopping of the motor, are easily adjusted by means of first and second rods mounted on the plates for rotation about axes parallel to the axis of rotation of the shaft, a pinion gear on the shaft. first rod connecting the circle of teeth of the first ring, a gear of pinion in the second rod connecting the circle of teeth of the second ring, and manipulative means manually at the ends of the rods, out of one of the plates, so as to allow adjustment of the rotation position of the cam surfaces by means of knobs that are accessible when the cover is removed. In the previous actuators of this type, it has been proposed to detect the position of the disc or other valve member by means of a potentiometer so that a signal representative of the position can be electrically transmitted to a remote location of the valve. For this purpose, the teeth of a pinion capable of rotating with an external portion of the arrow of the potentiometer in which its wiper blade is held are linked by a pulse gear mounted for rotation in the actuator housing in response to the rotation of the actuator. the valve between open and closed positions. As a potentiometer has a useful range through only about 270 ° rotation of its arrow, the gear teeth are related so as to rotate the potentiometer arrow through this range in response to only a quarter turn or other range of opening and closing movement of the valve. However, the interlinking between the pulse gear and the potentiometer shaft requires careful adjustment to ensure accurate results and avoid damage to them by forcing the wiper blade beyond its useful range in one direction or the other. In the past, this has required the user to access the potentiometer within the actuator housing to adjust fixed screws that hold the pulse gear in a desired rotational position with respect to the potentiometer shaft. One of the objects of this invention is to provide such a valve position indicator that is easy to adjust without risk of damage to the potentiometer, and additionally in which the desired position of the teeth in the potentiometer gear of the potentiometer shaft be determined automatically when the assembly is carried out without the need to fix screws and the like. In this way, as in the previous actuators of this type, the position of the valve stem is indicated electronically by means of a potentiometer having an arrow to rotate a pointing element beyond a cleaning ring throughout its useful range , and a potentiometer gear around an external portion of the potentiometer shaft and linking an impulse gear capable of rotating with the valve rod so as to rotate the pointer element in response thereto. However, according to another aspect of the invention, a portion of the periphery of the potentiometer gear is free of teeth so that it is not rotated beyond the useful range of the potentiometer. In this way, the remaining periphery is flat so that the pulse gear merely passes through the potentiometer gear on the arrow and does not continue to rotate it beyond the potentiometer's useful range. More particularly, means for adjusting the rotational position of the pulse gear, and hence the potentiometer shaft, are accessible when the housing cover is removed. Preferably, the potentiometer shaft is not round to fit tightly into a non-round hole in the potentiometer gear so as to set its rotational positions relative to each other. More particularly, the aforementioned means for adjusting the potentiometer are integrated with the arrangement described above to deactivate the motor since the pulse gear surrounds a third plate which is fixed to the shaft capable of rotating with the valve rod and in axially spaced relation with each of the first and second plates, to arrange teeth formed around its outside in position to engage the meshing teeth on the potentiometer shaft. More particularly, a third rod is mounted on the plates for rotation about axes parallel to the axis of rotation of the arrow, a pinion gear on the third rod links an inner ring of teeth of the ring gear, and means are provided on the shaft. end of the third rod out of the plate first mentioned for manual manipulation in order to allow adjustment of the arrow of the potentiometer. It is also preferred to provide such an actuator with means to visually indicate the position of the valve, particularly in its open and closed positions, which is located on or near the valve. Previous indicators have been proposed in which an internal cylinder capable of rotating in response to the valve stem, and having "open" and "closed" indicators around its circumference, which are representative of the position of the valve, is disposed within the an external cylinder that has transparent windows arranged to allow observation of the indices from almost anywhere around the valve. However, in previous actuators, these indicators have been difficult to install and to remove for replacement or repair. According to still another novel aspect of the invention, the position of the valve is indicated by means including an opening in the cover opposite an arrow end capable of rotating in response to the rotation of the valve stem, and a cylinder external that has abutment fingers to pass deformably through the hole and means in them engageable with the outer side of the wall when the abutment fingers are linked with their inner side around the hole, and an internal cylinder for releasable attachment with the arrow for rotation with it and disposition inside the external cylinder, the outer cylinder having transparent windows and the inner cylinder having indexes around it visible through the windows to indicate the valve arrangement in open and closed positions. More particularly, the means engageable with the outer wall include a flange around the outer cylinder having a groove and a seal of resilient material carried within and protruding from the groove to form a seal with the outer wall of the housing and to keep the stop fingers tightly against the inner side of the wall. As shown, the worm gear connectable to the valve rod so as to rotate the valve between open and closed positions has shoulders at opposite ends of a partial circle of teeth to link the worm, and stops are mounted on and extend towards the housing in position to be linked by the shoulders to prevent over-travel of the gear in any direction. More particularly, the stops are threaded into the housing so that they can be adjusted from the outside of the housing to move their surfaces to positions for attachment by the shoulders at different rotational positions of the gear. As described above, those parts of the actuator that rarely require repair or adjustment, such as the motor, the worm gear and the worm shaft with the worm gear and the cam in it, are mounted within the base of the housing below the switch plate. Those parts, such as the potentiometer, the torsion limit keys and various switches, which require more frequent adjustment or repair, are on the switch plate and thus accessible only when the cover is removed. Furthermore, since the manual wheel and the related parts of the overdrive assembly are easily and quickly assembled within the cavity in an outer wall of the housing, the assembly may be an optional feature, such as the torsion sensor keys. In the drawings, in which like reference characters are used to designate equal parts: Figure 1 is an end view of an actuator constructed in accordance with the present invention and mounted on a butterfly valve for use in moving its disc between open and closed positions; Figure 2 is a view of the actuator and the valve of Figure 1, as viewed from its right hand side; Figure 3 is a top view of the actuator, on an enlarged scale, with the cover removed from the base of the housing, as seen along broken lines 3-3 of Figure 1; and with the manual wheel removed to move the manual drive system to the linked position; Figure 4 is another top view similar to the figure
3, but with the inner wall (switch plate) removed from over the open upper end of the housing base; Figure 4A is a cross-sectional view of the manual overdrive assembly, on an enlarged scale and as seen along the broken lines 4A-4A of Figure 4;
Figure 5 is a vertical sectional view of the actuator, on an enlarged scale, and as seen along the broken lines 5-5 of Figure 6; Figure 5A is a cross-sectional view of the potentiometer and pulse gear for operating the potentiometer gear on its arrow, at an enlarged scale, and as seen along the broken lines 5A-5A of Figure 5B; Figure 5B is a vertical sectional view of the potentiometer and the pulse gear, as well as the cams for linking the limit switches to stop the motor in each of its valve opening and closing positions, as seen throughout. the broken lines 5B-5B of Figure 5A; Figure 6 is a vertical sectional view, amplified, of the actuator, as seen along the broken lines 6-6 of Figure 5; Figure 7 is a view of the actuator, partially in plan and partly in elevation, as generally seen along the broken lines 7-7 of Figure 5, showing the worm and the overdrive cam in neutral positions, as in Figure 5, and in this way during the operation of the valve in the absence of excessive torsion, shown with the overdrive linked; Fig. 8 is a view similar to Fig. 7, but where excessive twisting, due for example to an obstruction in the valve line, has moved the worm and the cam to the right to rotate one of the sensor fingers and This way deactivate the motor, shown with the linked overdrive; Figure 9 is an enlarged view of the torsion sensing mechanism, as seen along the broken lines 9-9 of Figure 11, and showing its fingers in a dependent position opposite the cam surfaces on the cam carried by The worm; Figure 10 is a view similar to Figure 9, but where the cam has been moved with the worm to the right so as to link and move the finger of the sensor key to the left in order to deactivate the motor, as shown in figure 8; Figure 11 is a view from the bottom of the torsion sensor device, as seen along the broken lines 11-11 of Figure 9; Figure 12 is a diagram of the electrical wiring inside the actuator, showing its connections to various switches as well as a diagrammatic illustration of the pointer element and the wiper blade of the potentiometer; and Figure 12A is another diagrammatic illustration of the pointing element and the wiper blade, with the pointing element moved to another position in response to the rotation of the ring gear fixed to the arrow capable of rotating with the valve rod. Referring now to the details of the drawings described above, the actuator, which is designated completely by the reference character 100, is shown in FIGS. 1 and 2 mounted on a butterfly valve indicated entirely by the reference character 101. As also shown therein, the butterfly valve comprises a body 102 having a passage 103 therethrough connected in alignment with a pipe 104 or other flow conduit, and a disk 105 mounted for rotation a quarter turn or 90 ° inside of the valve body between open (figure 1) and closed positions. A rod 106 for rotating the disk is connected thereto at its lower end and extends upwards through a neck 102A of the valve body for connection at its outer end with a pulse mechanism inside the actuator to thereby rotate the Valve stem and disc. A flange 107 on the neck of the valve body is connected to the underside of a base 111 of the actuator housing 110 by means of bolts or other suitable means, and a cover 112 is releasably connected to the open upper end of the base. The base of the housing is a forge having a projection 113 on its bottom wall on which a worm gear 114 of the drive mechanism of the actuator is mounted. The worm gear in turn has a sleeve 114A that extends down from its underside and narrowly towards the projection in a position to receive the upper end of the valve stem. The ends of the rod and the sleeve have non-circular mating surfaces, which allow the worm gear to impart rotary movement to the valve rod in opposite directions. The worm gear is held down in the position held on the projection by means of a sheave 114B retained by a snap ring around the lower end of the sleeve. The worm gear and thus the valve rod are adapted to be rotated in opposite directions in response to a reversible electric motor M, which is connected to the worm gear by a worm 115 carried by a worm arrow 116 held in the housing for rotation and longitudinal reciprocation transversely of the axis of rotation of the worm gear. In this manner, the arrow is received through and held to opposite ends by means of bearings 118 and 119 mounted within apertures in erect walls spaced on the underside of the base of the housing. The gear is connected to the arrow by a pin 117, which extends through them. A cylindrical gear 120 is releasably connected to the end of the arrow 116 for pulse connection with a motor gear 121 driven by the motor output shaft, as shown in FIG. 4, whereby the operation of the motor in an address in turn will rotate the worm arrow, the worm and the worm gear, and therefore the valve stem, in one direction, while the operation of the electric motor in the opposite direction will in turn turn the rod valve in the opposite direction, thus selectively moving the valve between open and closed positions. In a form that will be described below, the worm and the arrow on which it is mounted, are free to move longitudinally a limited extent, and for this purpose, and again as shown in Figure 4, the motor gear 120 it is sufficiently wide to maintain momentum linkage with the cylindrical gear 120 on the worm shaft during any such movement. A manual overdrive system for the actuator is mounted on the base of the housing at the right hand end of the worm arrow 115 and includes an external manual wheel 125 mounted on the outer end of a rod 126 whose inner end is in turn mounted for reciprocation within a cavity 127 formed at the right hand end of the base of the housing for displacement between an internal position (FIG. 5) in which the manual overdrive is disengaged and an external position (FIGS. 7 and 8) in the which manual overdrive is linked. More particularly, the right-hand end of the worm shaft and the inner end of the rod are constructed so that, as will be described in the following, the arrow is free to move a longitudinally limited extent without linking the manual overdrive during the sequence of the actuator driven by the electric motor. As best shown in Figures 5,7 and 8, the manual overdrive system includes a liner 130 that is releasably held within the cavity 127 on the right-hand side of the housing base by means of a ring. pressure 131, and surrounds a sleeve 132 at the inner end of the rod by means of a pin 133 extending therethrough. Alternatively, the sleeve can be an integral part of the rod. More particularly, the sleeve is of such size that it receives the right-hand end of the worm arrow, and the liner links a shoulder in a plate 138 within the cavity to place the bearing 119 through which the end extends by hand right of the worm arrow. The manual wheel 125 is held in any of its positions linked or disengaged by means of ball stops 135 which are spring-biased towards one of the longitudinally spaced slots 136 and 137 around the inner diameter of the liner. Seal rings are arranged around the external and internal diameters of the outer end of the liner to prevent the passage of foreign matter into the interior of the actuator. As best shown in Figure 4A, the inner diameter of the sleeve has a series of arcuate grooves 140 formed around its left hand end, and a pin 141 is slidably received through the right hand end of the arrow worm for arranging its external protruding ends in position to fit within opposing radial grooves in the sleeve. When the manual wheel is pulled outward, as shown in Figures 7 and 8, the ends of the pin fit within a pair of slots so as to provide a rotary pulse connection between the manual wheel and the worm arrow for a turn the worm gear manually and in this way rotate the valve rod. However, when inward movement of the hand wheel and the shank occurs, the pulse pin moves out of the slots, as shown in FIG. 5, to release the worm arrow 116 from rotation by the hand wheel . The manual overdrive system also includes means for automatically deactivating the electric motor before the movement of the overdrive to its linked position. To this end, a switch 145 is mounted on the upper side of the base of the actuator housing in a position to actuate to deactivate the motor as the overdrive arrow 132 moves outward with the hand wheel to the position of FIGS. 8. Then, upon returning the overdrive arrow to its internal position disconnected from the worm arrow, the sleeve 132 will trip the switch so that it is set to again deactivate the motor in case the operator decides to link the manual overdrive. The switch is mounted on a clamp which in turn is mounted on an internal wall 147 of the housing, which is bolted or otherwise secured to the open upper side of the housing base to cover a recessed portion of the housing base. Also as previously described, it serves as a switch plate, and with other walls of the base of the housing, encloses a lower compartment below it for those parts that normally do not need to be accessed by the operator and with the cover 112 and the compartment upper enclosing those parts that require adjustment or repair, merely by removing the cover 112. The switch itself is adapted to be activated by a rod 148 extending through aligned holes in the inner wall and the base of the housing as well as through of the liner 130 for arranging its lower end for attachment by the overdrive arrow 132. In this way, the rod is held up by the overdrive arrow when the manual overdrive is in its disengaged position, to close the mode switch to allow the engine to operate. On the other hand, when the sleeve is moved to the right by the movement of the hand wheel to the linked position, the rod is depressed downward to open the switch. The end of the overdrive arrow is bevelled to facilitate its cooperation with the inner end of the rod. As will be seen from a comparison of figures 7 and 8, the pin 141 maintains its connection with a pair of slots, in spite of the limited longitudinal movement of the worm arrow with respect to the housing, and in this way with respect to the manual overdrive arrow that is mounted in the housing, in response to the excessive twisting, as will be better understood from the following description. The worm arrow is also surrounded by a cam 150 which, as shown, is formed integrally with the right end of the worm, although it can be separated from it, so that, like the worm, it is fixed to the arrow. The worm shaft is also surrounded by two sets of Bellville 151 springs, one of which is pre-compressed between the left-hand end of the worm and the wall of the base of the housing in which the left bearing 118 and the another of which is between the right-hand end of the cam and the right-hand bearing 119 mounted on the opposite wall of the base of the actuator housing. As previously described, during normal operation of the actuator, these springs are pre-compressed to maintain the worm and the cam, and in this way the worm arrow to which they are fixed, in a "neutral" position in which each set of springs is equally compressed. However, in case the valve finds excessive torque, such as when there is an obstruction in the line, the resulting resistance to rotation is transmitted through the worm and the cam to make one of the sets of the springs be further compressed, such as the right hand assembly shown in Figure 8, in case of a resistance of the opening movement of the valve. On the other hand, in case the resistance is closing the valve, the set of springs can be compressed on the left. In the valve assembly, with the manual overdrive system removed from the cavity at the base of the housing, the worm and the cam, together with both sets of springs, are axially aligned with the bearings spaced in the housing to allow the worm arrow 116 (with the cylindrical gear 120 removed from its left end) is inserted through the cavity, the right hand bearing, the worm, the cam, the springs and the bearing on the left hand side. In this way, upon the installation of the manual overdrive system, the bearing plate 138 at the left end of the sleeve and the liner 130 will apply force to the right hand bearing 119 to compress the springs so that, when the liner connection occurs in the cavity, the worm and the cam are kept in a neutral position. All of the above is realized, of course, before the installation of the worm gear in connection with the worm and, of course, the optional installation of the torsion-limiting sensors (to be described) in the positions shown in figures 5, 7. and 8, from above the inner wall of the housing. Also, of course, the cylindrical gear 120 would be connected to the left end of the worm shaft for pulse linkage with the motor gear. As previously described, the means for deactivating the motor, and thus preventing the destruction of the clogged valve disc, in response to a predetermined torque, comprise tapered cam surfaces 155A and 155B (see FIGS. 9 to 11) around the cam, and a pair of keys 160A and 160B mounted on a clamp B secured to the inner wall of the housing. A finger of a key is thus arranged to be engaged by a cam surface, in case of excessive twisting during the movement of the valve rod in one direction, and the other to be linked by the other cam surface in the case of torsion excessive during movement of the valve stem in the opposite direction. More particularly, a pair of switches 161A and 161B are also mounted on the clamp, each in position to be linked by one of the keys so as to deactivate the motor when the finger of that key is pivoted a predetermined extension due to the linking with one of the cam surfaces. In this manner, the clamp B is disposed on an opening 162 formed in the inner wall of the housing base to allow the fingers of the keys to depend therethrough to positions between the cam surfaces on the cam, as shown in FIG. Figures 9 to 11. More particularly, each key is pivotally mounted on the clamp by means of a pin 163 extending therethrough and mounted at opposite ends on opposite walls 164 of the clamp. The switches are fixedly mounted on the clamp by means of pins 165 extending therethrough and the opposite walls of the clamp, each with a button 166 arranged to engage with a key when the key pivots a predetermined extension by a key. of the cam surfaces. In this way, as shown in Figure 11, the keys and switches are laterally spaced, each being adjacent to a side wall of the clamp. Lever arms 167A and 167B are arranged around the arrow keys between the keys and switches, so that a free end thereof is disposed below a switch button, as shown in Figure 9, when the The arm is not stressed, so that the finger is merely arranged in position to be linked by a cam surface. However, when the key is pivoted when the cam surface is engaged with your finger, the free end of the arm is moved up to press the button of the switch and thus activate the switch, when the key has been swung a predetermined extension by means of the longitudinal movement of the cam surface with the worm arrow, and in this way deactivate the motor. As shown, the arms are aligned so as to minimize the width of the clamp. Also as shown, the end of each lever arm is disposed opposite a screw 168 mounted on each key, whereby the screw can be adjusted to adjust the force at which the switch linked by the arm is activated. Also as previously described, one of the novel aspects of the present invention is the ability of the user of the actuator to either incorporate or remove the above described mechanism to deactivate the motor in the case of excessive torsion. In this way, if it is to be used, it is only necessary to mount the clamp in the position shown and connect it releasably to the inner wall by means of screws, in this way moving the fingers dependent on the keys through the hole in the inner wall to opposite positions of the cam surfaces. If this torque limiting feature is not going to be used, the cam and worm combined can be replaced by a worm, and the clamp with the sensor fingers would not be installed. A free clamp can be used to cover the opening in the switch plate. As shown, the clamp for closing the switch 145 of the manual overdrive mechanism is also mounted on the flange in the same clamp. As best shown in FIG. 4, the meshing teeth are arranged only around that portion of the worm gear 114 which, during operation of the actuator, is linked by the worm in the worm shaft. Shoulders 170 and 171 are formed in portions peripherally spaced from the remainder of the circumference of the worm gear at opposite ends of the teeth in a position to be linked by the internal ends of the pins 172 and 173 threadedly connected through holes in one side of the body. base of the actuator housing. As shown in Figure 4, these bolts are held in place by nuts that allow the user of the actuator to adjust the internal ends of the bolts, and in this way the positions in which the worm gear would stop, and therefore the valve stem, in an emergency situation, ie in which the actuator would otherwise be free to rotate the valve stem beyond its desired open or closed position. As previously described, the switches are mounted within the actuator in a position to be actuated so as to deactivate the motor, in response to the rotation of the valve stem and thus the valve member to one of its positions. More particularly, as best shown in Figures 3 and 5, the upper and lower limit switches 175 and 176 are mounted in a vertically spaced relationship on the inner wall of the base of the housing with sensors there disposed opposite to upper and lower cam rings similarly spaced 177 and 178, respectively, surrounding and capable of rotating with an upper arrow 180 capable of rotating with the gear 114 of the pulse mechanism, and thus in direct response to the rotation of the valve stem. As shown in Figure 5B, this cam arrow extends narrowly through a sleeve 181 in the inner wall 147 for releasable connection at its lower end to the worm gear. In this manner, the upper side of the worm gear has a slot 182 which is adapted to closely receive a tongue 183 on the lower end of the cam arrow so that the arrow and cam rings mounted therein can be removed or replaced. from inside the upper housing compartment without removing the inner wall. As shown, each of the cam rings has a cam surface 177A and 178A formed around its periphery opposite one of the limit switches. With the valve being able to rotate a quarter turn, these cams have their high sides rotationally displaced around 90 °. Assuming that the upper cam ring 177 is the valve closing cam, and as shown in Fig. 5, its high point will activate the upper limit switch 175 when the valve is moved to the open position in response to the rotation of the worm gear. with the valve stem in a rotational direction. Then, upon the return movement of the valve to its closed position, the raised point on the lower cam ring 178 will move approximately 90 ° so as to operate the limit switch 176 to deactivate the motor upon reaching the valve its closed position in response to the rotation of the worm gear with the valve rod in the opposite rotational direction. As indicated in the diagram, the switches can be closed to reactivate the motor and in this way return the valve to the open or closed position, by means of externally activated switches of the actuator. As previously described, this assembly for operating the limit switches is similar in construction to that shown in the aforementioned U.S. Patent No. 5,305,781, where similar cam rings are used to provide an indication of the position of the valve in a remote place. Thus, as in the prior patent, it provides a unique arrangement for independently adjusting the rotational position of each cam ring, when required, merely by removing the housing cover from its base. In this way, the cam rings are supported on and are capable of rotating with the cam arrow 180 and have engaging teeth 190A and 190B around their inner periphery which are linked with pinion gears mounted on rods 191A and 19IB which are extending upwards the knobs 192A and 192B on the upper end of the assembly, the knobs in this way providing means by which the cam rings can be manually adjusted. The rods also extend through the plates 193A and 193B which are fixed to the arrow by means of pins 194A and 194B and through which the rods extend. More particularly, these plates are disposed above and below each of the cam rings and are received through recesses in separator plates disposed between the other plates. Also as previously described, the location of the valve is adapted to be remotely observed by means including a potentiometer 200 mounted on the inner wall 147 of the housing base by means of a clamp 201 releasably connected thereto, and a potentiometer gear 202 capable of rotating with the lower end of the potentiometer shaft 203 for movement by means of a pulse gear 204 disposed opposite thereto and capable of rotating in response to the valve stem. More particularly, according to another novel aspect of the invention, this pulse gear 204 is mounted on the same arrow 180 on which the cam rings are mounted by means of a plate 205 which surrounds closely and which is fixed to the arrow by
* means of a pin 207. Teeth formed around the internal periphery of the pulse gear 204 link a pinion gear 208 which is mounted on the lower end of a rod 209 which, like the cam ring adjustment rods, extends between a knob 210 at its upper end and the pinion gear that rotates within a recess in a spacer plate on the mounting plate 205 and below the spacer plate for the lower cam ring 178. This then allows the engagement of The ring is rotated in any direction from an easily accessible place on the inner wall of the base of the housing, and in this way correct any lack of adjustment of the potentiometer without the need for access to and manipulation of fixed screws and the like, as was the case in the prior art. The container for the potentiometer, which is properly oriented in the clamp by a tab on its side adapted to closely fit within a slot in the clamp, can be of conventional construction having, as shown diagrammatically in FIG. 12, a cleaner 220 on which a pointing element 221 mounted on the arrow of the potentiometer 203 is adapted to move in order to vary the output of the potentiometer and thus remotely indicate the position of the valve. For this latter purpose, the end of the potentiometer shaft has a flat side 222
(figure 5A) forming a non-round configuration adapted to fit closely within a hole in the potentiometer gear capable of rotating with the arrow so as to allow the pointer element to properly relate the cleaner to the rotational position of the valve. As previously indicated, and as is well known in the art, a potentiometer has a useful range of only about 270 °. In this way, in response to the rotation of the valve 90 ° between open and closed positions, the pointer element will oscillate approximately 270 °. This is achieved of course by an adequate relationship between the teeth of the ring gear with those of the pinion gear on the potentiometer shaft. According to another novel aspect of the invention, the F-side of the partial gear in the arrow of the potentiometer is flat between the teeth around it, adapted to link the ring gear during rotation of the pointer element through the entire range active potentiometer. As a result, the partial gear can not turn the potentiometer out of its active range, as its teeth will move first out of engagement with the potentiometer gear. This, of course, is true for partial gear rotation during opening or closing of the valve. As previously described, this eliminates the possibility of a false signal emanating from the valve actuator. Means for indicating the position of the valve in or around its place comprise an inner cylinder 230 having "open" and "closed" indexes about its circumference and its upper conical end and releasably mounted on the upper end of the arrow 180 on which the cam rings described above are mounted. An outer cylinder 231 is mounted on the upper wall of the housing cover in position to surround the internal cylinder to allow observation of the indices in the internal cylinder. In this way, as shown, the outer cylinder has windows arranged around its circumference, as well as around its conical upper end, so as to allow the observer to observe the position of the valve, as indicated by the position of those indexes. in response to the rotation of the arrow, as shown in Figures 5 and 6. More particularly, the inner cylinder has a rod 232 at its lower end having transverse grooves adapted to be received closely within transverse grooves at the upper end of the arrow 180 in which the cam rings and the meshing ring are mounted to cause their rotation with the arrow and thus with the valve stem. In this way, the lower end of the inner cylinder can be merely moved downward, through an opening 233 for linking the upper end of the arrow, which automatically coordinates the "open" or "closed" indexes with corresponding positions of the valve. Obviously, other indices can be used to indicate open or closed positions. The cylindrical and upper conical portions of the outer housing fit tightly into corresponding portions of the inner cylinder when the outer cylinder is releasably mounted in the cover of the housing, and with the windows disposed opposite the indexes. For this latter purpose, the lower end of the outer housing has spring fingers 240 or stops adapted to fit tightly through the opening in the cover to allow its lower ends 241 to fit below the inner side of the cover as it moves through. of the opening in the cover. More particularly, there is a flange 242 around the outer housing that links its upper side as the stops move into position. There is a flange that contains an elastic seal ring 243 of such size that it projects normally from the underside of the flange. In this way, it serves not only to form a seal or at least a barrier to foreign materials between the outer cylinder and the cover, but also to deformably urge the outer cylinder upwards and thus stop the stops linked in shape. tight with the inner side of the cover. As shown in Figure 3, the base of the housing includes a second inner wall 244 which is disposed over the lower compartment of the base not covered by the first inner wall. This wall, like the first wall, is adapted to be fastened to the open upper end of the base. It has switch banks mounted therein and serves, together with the other inner wall, to separate the upper and lower housing compartments from each other, and more particularly to house certain of the most permanent components of the actuator, including the motor and the associated wiring . Wall 147, when in place, covers other parts that do not require frequent replacement, such as worm arrow, worm and cam, as well as Bellville springs mounted on the arrow, worm gear and stops. . Parts of the actuator that, on the other hand, may require adjustment, are accessible for that purpose on the internal walls when the cover is removed from the base of the housing. This, of course, includes the knobs on the upper ends of the rods that lead to the cam rings as well as the impulse gear to adjust the potentiometer, the torsion sensor, the potentiometer itself, as well as the safety switch and the limit switches. The wiring diagram in Figure 12 includes a schematic illustration of the partial gear on the potentiometer shaft and the pulse gear to adjust the potentiometer, as well as the proximity switches that respond to the opening and closing cams, and the switches that respond to the torsion response keys. 12A shows the partial gear of the potentiometer shaft moved from the position of FIG. 12. The wiring is also shown to connect the potentiometer to an extension of the remote position indicating housing. From the foregoing, it will be seen that this invention is a well-adapted invention to achieve all the purposes and objectives set forth herein, together with other advantages which are obvious and which are inherent in the apparatus. It will be understood that certain characteristics and subcombinations are useful and can be used without reference to other characteristics and subcombinations. This is contemplated by and is within the scope of the claims. Inasmuch as many possible embodiments of the invention can be made without departing from its scope, it will be understood that all the material indicated herein or shown in the accompanying drawings must be interpreted as illustrative and not in a limiting sense.