US2805579A - Actuating mechanism - Google Patents

Description

8 Sheets-Sheet 2 Filed June 22, 1956 I fj y gw M IIL 'ATTORNEY Sept. 10, 1957 w. F. DEHN ACTUATING MECHANISM Filed June 22, 1956 man n! 8 Sheets-Sheet 3 jaz y. 11.

v INVENTOR WILLIAM F.DEHN

AT TOR NEY w. F. DEHN ACTUATING MECHANISM Sept. 10, 1957' 8 Sheets-Sheet 5 Filed June 22, 1956 \TIDOO INVENTOR WILLIAM F. DEHN ATTORNEY Sept. 10, 1957 w. F. DEHN 2,805,579

ACTUATING MECHANISM 8 Sheets-Sheet 6 j g? 32. spy/3 p35 6/ Filed June 22, 1956 INVENTOR WILLIAM F. DEHN AT TORNEY Sept. 10, 1957 Filed June 22, 1956 8 Sheets-Sheet 7 INVENTOR WILLIAM F. DEHN BY 96w ATTORNEY Sept. 10, 1957 w. F. DEHN 2,805,579

ACTUATING MECHANISM- Filed June 22, 1956 8 Sheets-Sheet 8 2 .46. fig" .Z M8 4 //3 M I M8 //3 M/ xxxyxxm E INVENTOB WILLIAM F. DEHN.

BY m

ATTORNEY United States Patent ACTUATING MECHANISM William F. Dehn, Wauwatosa, 'Wis., assignor to Allen- Bradley Company, Milwaukee, Wis., a corporation of Wisconsin Application June 22, 1956, Serial No. 593,167

17 (llaims. (Cl. 74-99) This invention relates to an actuating mechanism, espe cially but not exclusively adapted to produce a short and early trip of a switch of the type biased to return to its original position when not being actuated by the trip actuating mechanism; and resides more particularly in an actuating mechanism which includes a rotatable member capable of limited rotation back-and-forth under external actuation; a substantially linearly reciprocable follower member, for the output of linear motion to an actuated mechanism; and means for converting the rotary motion of the rotatable member into translation of the follower member, said converting means comprising: a pair of cams, with their cam-surfaces facing each other, and relatively moveable toward each other in response to the rotation of the rotatable member; means guiding the reciprocation of the follower member; a pair of interen'gaging rollers, journaled on the follower member, side by side laterally with respect thereto, and each rolling on the cam-surface of one of the cams; and means (preferably resilient) biasing the follower member to move in one given direction along the guide means; the cam-surfaces being so positioned and having such conformations as, by their pressure on the rollers, to tend to move the follower member along the guide means in the direction opposite to the given direction.

In one species of the invention one cam of the pair is motionless and the other cam of the pair is moveable toward the first, and the two rollers are shiftable laterally with respect to the follower member. In the preferred variant of this species, there are two such pairs of cams, one of which pairs functions when the rotatable member is rotated in one direction from dead center, and the other of which pairs functions when the rotatable member is rotated in the opposite direction from dead center.

In a second species of the invention the two cam surfaces are symmetrical with respect to the line of translation of the follower member, and move toward each other in unison, when the rotatable member is rotated in either direction from dead center. In this species, the two rollers are loosely journaled to permit them to always interengage, and to permit some slight further lateral shift to take account of dilference in lever-arm.

It is the principal object of the invention to provide a. novel and simple conversion mechanism for the tripactuation of a switch of the type usually referred to as spring-return, so that the conversion mechanism and the switch proper shall together constitute a spring-return limit-switch.

It is a further object of the invention to provide such a mechanism, in which the rotary motion of an externally actuated rotary member will be converted into translation of a switch-tripping member, in such manner that the trip will occur quickly during a short angular travel of the rotatable member, with but slight overtravel of the following member after it has tripped the switch.

However, it should be understood that the invention is not limited tothe actuation of a spring-return limit-switch,

nor any kind of switch, nor even any mechanism springreturned, but may be used with any actuated mechanism (not necessarily electrical) which the invention is capable of actuating, such for example as a cut-out, either automatic reset, or even hand reset. Nor is the invention limited to producing any particular sequence of speeds of operation. To this end the cam-surfaces may have any appropriate configuration.

These and other objects and advantages ofthe invention will appear in the description to follow. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there are shown, by Way of illustration and not of limitation, two specific forms in which this invention may be embodied.

In the drawings:

Fig. l is an actual-size front elevation of the operatinghead (containing the actuating mechanism of the present invention), mounted on top of the actuated switch-proper.

Fig. 2 is an actual-size side elevation of the same, viewed as seen from the right in Fig. 1.

These first two figures are applicable to either species of the invention.

Fig. 3 is an enlarged front elevation, of a portion of the operating-head of the first species of the present invention, mounted on top of an actuated switch-proper (which may constitute the mechanism actuated by either species), the lower part of the figure being cut-away to show the actuating connection between the two mechanisms.

All the remaining figures are to the same enlarged scale as Fig. 3, except that Figs. 27 to 30 and 46 to 49 are to an even more enlarged scale. I

Fig. 4 is a plan view of the operating-head casing of the first species.

Fig. 5 is a rear elevation of said casing, showing the centering-spring assembly in place.

Fig. 6 is a front elevation of said casing.

Fig. 7 is a vertical section of said casing, viewed as though out along the line 77 of Fig. 4.

Fig. 8 is a vertical section of said casing, viewed as though out along the line 88 of Fig. 7.

Fig. 9 is an edge elevation of the follower of the first species.

Fig. 10 is a side elevation of said follower.

Fig. 11 is a plan view of said follower.

Fig. 12 is a side elevation of the double moveable cam of the first species.

Fig. 13 is a plan view of said cam.

Fig. 14 is an end view of said cam.

Fig. 15 is a left-hand end view of the shaft of the first species.

Fig. 16 is a side elevation of said shaft.

Fig. 17 is a right-hand end view of said shaft.

Fig. 18 is a section of said shaft, viewed as though out along the line 18-18 of Fig. 17.

Fig. 19 is a side elevation of one of the two identical spring levers common to both species of the present invention.

Fig. 20 is an edge elevation of said lever.

Fig. 21 is a side elevation of the spring stop common to both species.

Fig. 22 is an edge elevation of said spring stop.

Fig. 23 is a side elevation of the centering spring common to both species.

Fig. 24 is an elevation of said spring, as seen from the right in Fig. 23.

Fig. 25 is a vertical section of the operating head to the first species, viewed as though out along the line 2525 of Fig. 26. V

Fig. 26 is a vertical section of the same, viewed as though out along the line 26-26 of Fig. 25. i

Fig. 27 is a much enlarged-portion of the vertical section of Fig. 26, showing the positions of the crucial elements of the actuating mechanism of the first species, when the shaft is on dead-center.

Fig. 28 is the same, with the shaft rotated degrees counter-clockwise from dead-center.

Fig, 29 is the same, with th shaft rotated 40 degrees counter-clockwise from dead-center. N

Fig. 30 is the same, with the shaft rotated 55 degrees counterclockwise from dead-center.

Fig. 31 isa plan view of theoperating-head casing of the second species of the present invention.

. Fig. 32 is a vertical section of said casing, viewed as though out along the line 32'-32 of Fig. 31.

Fig. 33 is a vertical section of said casing, viewedas though cutalong the line 33'-33 of Fig. 32.

; Fig. 34 is an edge elevation of the follower of the second species.

Fig. 35 is a side elevation of said follower.

Fig. 36 is a plan view of said follower.

' Fig. 37 is an edge elevation of one of the two identical cams of the second species.

Fig. 38 is a plan view of said cam.

Fig. 39 is a side elevation of said cam.

Fig. 40 is a left-hand view of the shaft of the second species.

Fig. 41 is a side elevation of said shaft.

Fig. 42 is a section of said shaft, viewed as though out along either of the .two lines 4242 of Fig. 41.

Fig. 43 isa plan view of said shaft.

Fig. 44 is a vertical section of the operating head of the second species, viewed as though cutalong the line 44-44 of Fig. 45. a

Fig. 45 is a vertical section of the same, viewed as though out along the line 45--45 of Fig. 44.

Fig. 46 is a much enlarged portion of the vertical section of Fig. 45, showing the positions of the crucial elementsof the actuating mechanism of the second species, when the shaft is on dead-center.

Fig. 47 is the same, with the shaft rotated 5 degrees counter-clockwise from dead center.

Fig. 48 is the same, with the shaft rotated 40 degrees counter-clockwise from dead-center.

Fig. 49 is the same, with the shaft rotated 55 degrees counter-clockwise from dead center.

Throughout the description, the same reference number is applied to the same member or similar members.

Referring now to the drawings, more particularly Figs. 1 and 2, which are drawn to actual size, it will be seen that 51 is the operating-head casing, which serves a support for the actuating mechanism of the present invention. This actuating mechanism, and the internal details of the casing, differ between the two species which will be hereinafter described; but the external appearance of the two sorts of operating-heads is practically the same.

52 is the case which contains the actuated switch,

which can be the same for both species.

Operating-head casing 51 can be secured to switch case 52 (oriented in any one of four directions) in any convenientmanner such asfour screws 53, which also serve to hold in place domed cover-plate 54. When the operating-head is not attached to the actuated switch, coverplate 54 is held in place by two small drive-screws 55.

Bushing 56 is secured to casing 51 in any convenient manner, such as by screws 57. Through this bushing, there projects shaft 58, to which shaft there is secured in any convenient manner (as by clamping pin 59 and nut 60) a lever arm 61, at the extremity of which. there is journaled a roller 62.

The impact against this roller 62 of some moving stop or stops (not shown) is what supplies ,the external actuation to impart a limited rotation to shaft 58, thus setting in motion asuccession of elements to trip and untrip the actuated switch.

. Referring nowto Fig. 3, there will be described. a mechanism which may be employed to operationally connect the actuating mechanism within the operating-head to the actuated mechanism within the switch, if and when the invention is used with such a switch.

63 is a vertically moving plunger, the vertical reciprocation of which shifts the switch from one to the other of its two settings. The details of this internal operation of the actuated switch are shown and described in applicants copending application, Serial No. 487,096, for Snap Action Mechanism, filed Feb. 9, 1955, and in copending application of applicant and Wilson, Serial No. 364,544, for Contact Actuating Quick Action Switch, filed June 29, 1953, to which applications reference is hereby made.

Plunger 63 is shown in Fig. 3 hereof in its extreme lower position. It is biased by a spring (not shown herein) to assume its extreme upper position.

64 represents the bottom ends of two of the four legs of a doubly bifurcated follower. This follower is shown in Fig. 3 in its lowermost position which is the position it assumes when shaft 58 is on dead-center. Rotation of this shaft, in either direction from dead-center, raises the follower by means which will hereinafter be described.

Operational contact between plunger 63 and follower 64 is maintained by an actuator, the head 65 of which engages the legs of follower 64, and the point 66 of which engages the top of plunger 63.

A narrow male-threaded portion of head 65 extends downwardly through the center of a diaphragm 67 of flexible stretchable oil-impervious material such as rubber and thence through a hole in the. top of an inverted cylindrical cup 68. Onto this male-threaded portion of the head, there is screwed female-threaded actuator-point 66, thus clamping diaphragm 67 between head 65 and point 66. The outer edge of diaphragm 67 is in turn clamped between the lower surface of casing 51 and the upper surface of case 52.

Thus the assembly, thus described, effectively seals off the escape of oil from the actuating mechanism in headcasing 51, to the actuated switch mechanism in case 52; and yet permits downward motion of follower 64 to be freely transmitted to plunger 63, and permits upward motion of follower 64 to permit plunger 63 to move freely upward under the influence of its own spring. In other Words, the follower and the plunger, with the actuator between them reciprocate vertically as a unit, and yet permit upward overtravel by follower 64 when plunger 63 has reached its upward limit. For further showing and description of this diaphragm-actuator assembly, see above-mentioned application, Serial No. 487,096.

Inasmuch as the actuating mechanism of the present invention can be employed with other sorts of actuated mechanism than the spring-return switch above referred to and partially described, other and different connecting means than the actuator 65 to 68, or no such means, could be employed, and another and different actuated element than the plunger 63 could be employed. But some means, either automatic or otherwise actuatable, should be provided to return the actuated mechanism to its pro-actuated condition.

Operating-head casing 51 will now be described, with reference to Figs. 4 to 8, 25 and 26.

First consider front elevation (Fig. 6) and rear elevation (Fig. 5).

69 are holes for shaft 58. 70 are holes for bushingscrews 56. 71 is a cavity for a bearing 72, hereinafter described, for shaft 58.

73 is a cavity to hold the entire centering spring assembly, consisting of two spring levers 74, spring stop 75, and spring 76. 77 is a slot, to contain the head of spring stop 75. 78 and 79 are shoulders, to arrest the rotation of spring lever 74. The assembling of this assembly and operation will be discussed hereinafter, in connection with Fig. 25.

Turning :now to Fig. 4, the plan view of casing 51, and the two verticalsections thereof, Figs. 7 and 8, it will be 5 seen that 80 are four holes for screws 53, and 81 are two holes for drive screws 55. 82 is a vertical hole through casing 51. i

83 are four vertical ribs, defining four narrow vertical slots 84 and two wide vertical slots 85.

The upper portions of ribs 83 also constitute fixed cams, rigid with their support: i. e., the casing 51. The two left hand ones of the cams can be considered functionally as a single cam, inasmuch as they are identical and function jointly. Similarly as to the two right hand 08.1118.

The four narrow slots 84 serve to receive slidably the four legs 86 of follower 64. To avoid any possibility of attempting to assemble the contents of casing 51 upsidedown, narrow slots 84 .are narrowed slightly further at their bottom ends so that legs 86 cannot be inserted from that end.

At the bottom ends of-ribs 83 are cut-away portions 87, to permit the insertion of the head 65 of the actuator, as described in connection with Fig. 3; but shoulders 88 prevent upward travel of the actuator further than is necssary to permit the plunger 63 to trip the switch.

Figs. 9, 10, and 11 show respectively an edge elevation, a side elevation, and a plan view of follower 64. As already mentioned, this follower has four legs 86. In each side there is a horizontal slot 89, to permit the axles 96 of rollers 91 to slide laterally, so that the rollers can constantly engage each other and the respective camsurfaces, as will be hereinafter described. Each axle is free to slide lengthwise of its roller. When the follower is assembled in operating-head casing 51, the walls of hole 82 (see Fig. 4) maintain the axles in the rollers.

Figs. 12, 13, and 14 show respectively a side elevation, :a plan view, and an end elevation, of double moveable cam 92. This cam is rigidly assembled to shaft 58, and rotates with it. The upper surface of the cam, from A to B, serves as a double earn-surface for one or the other of rollers 91, as will be explained hereinafter, when discussing Figs. 27 to 30. The surfaces from A to D, and from B to C, [are "concentric with the axis G of the shaft. The surface from E to F fits crosswise diametrically to the shaft. There is a screw-hole 93.

Figs. 15, 16, 17, and 18 show respectively a left-hand end view, a side elevation, a right-hand end view, and a cross-section, of shaft 58. 94 is. a slot for the insertion of a screwdriver, to steady the shaft when adjusting leverarm 61 on the shaft. 95 is a squared portion, to receive certain elements of the centering spring assembly, as will hereinafter be described. 96 is a screw-hole. 97 is a diametric transverse slot, to receive the surface EF of cam 92. 98 are cut away portions, to avoid interference with the cross-head 99 of follower 64 (see Fig. when the follower is in its lowest position. 100 is a cut-away portion, for flat abutment of screw 101 (see Figs. 25 and 26).

Figs. 19 and 20 show respectively a flat elevation and an edge elevation of spring-lever 74. This lever has a hole 102 to engage squared-end 95 of shaft 58, and a projection 103 to engage alternately the two ends of centering spring 76, and to stop against shoulders 78 and '79 in cavity 73 of casing 51 (see Fig. 5).

Figs. 21 and 22 show respectively a flat elevation and an edge elevation of spring-stop 75. It has a circular hole 104, to permit free rotation of the shaft therein; a head 105 to fit in slot 77 of casing 51 (see Fig. 5) and thus hold spring-stop 75 against rotation; and a neck 106 to engage alternately the two ends of centering spring 76.

Figs. 23 and 24 show two elevations of centering spring 76, which is a nested circular leaf-spring, severed as at 107.

The assembling of the operatinghead mechanism will now be explained, with particular reference to Figs. 25 and 26. Reference will also be necessary to some of Figs. 4 to 24, from time to time.

Shaft 58 is first inserted through holes- 69 in casing 51.

Bearing 72 and bushing 56 arethen applied over the left-hand end of the shaft, and are secured in place by screws 57. 7

Cam 92 is inserted, proper side up, into casing 51 from the top, with the ends of the cam in the two slots 85, until surface EF of the cam fits into transverse slot 97 of shaft 58, and the two are then rigidly joined together by screw 101, inserted from beneath. The sides of the ends of cam 92, by bearing against the sides of slots 85, prevent the withdrawal of shaft 58 in either direction. 1

The four legs 86 of follower 64 are then inserted from above into the four slots 84, and the follower is dropped astraddle of shaft 58.

Lever 61 can be secured to the projecting end of shaft 58 by means of clamping pin 59 and nut 60 (see Figs. 1 and 2) at any convenient time. It is usually secured inverted, for shipment.

The centering spring assembly is assembled as follows in cavity 73 of casing 51. With shaft 58 in the angular position shown in Figs. 5 and 25, one of the two spring levers 74, then spring stop 75, and then the other spring lever 74, are slipped over the squared end 95 of shaft 58, with the head of the spring stop in slot 77 of the casing, and the projections 103 of the two spring levers aligned with the neck 106 of the spring stop. Spring 76 is then opened up at severance 167, and is slipped in, surrounding the two spring levers 74 and the spring stop 75. The two severed ends of the spring butt against the sides of projections 103 of the spring levers and neck 106 of the spring stop.

The centering assemblage operates as follows to center shaft 58. The shaft can be rotated about 55 degrees counterclockwise or clockwise, until projections 163 strike shoulders 78 or 79 respectively. The result of counterclockwise rotation is shown dotted in Fig. 5. One severed end of spring 76 has been. pushed counterclockwise by projections 74, the other end remaining butted against neck 106, thus spreading the spring. The resulting tension set-up in the spring, tends to restore the shaft to deadcenter, i. e. the full-line position shown. Similarly with rotation clockwise.

The final step in assembly is to place cylindrical helical spring 108 on top of follower 64, and to fasten cover plate 54 in place with drive-screws 55. The dome 199 of the cover plate compresses helical spring Hi8 slightly, and the back fiat portion of the cover plate holds the just described centering assemblage from falling out. Spring 108 should preferably be twice as strong as the returnspring of the actuated mechanism, or corresponding resistance-element, if any.

As introductory to a discussion of how follower 64 is caused to reciprocate, it should be noted that, from an operational point of View the cam-surfaces of each pair of ribs 83 constitutes a single cam-surface. When shaft 58 is rotated counterclockwise, rollers 91 are acted upon between one pair of cams, i. e.: the right-hand camsurface of movable cam 92, and the fixed cam-surface afforded by left-hand ribs 83; the left-hand cam-surface of cam 92 and the cam-surface of left-hand ribs 83 being inoperative. Vice versa, when shaft 58 is rotated clockwise.

Thus there are seen to be two pairs of cams, one of which pairs engages the two rollers 91 when shaft 58 is rotated in one direction from dead center, and the other of which pairs engages the tWo rollers when the shaft is rotated in the opposite direction from dead center. Also it is seen that, of each pair of cams, one cam (i. e., that formed by ribs 83) is held rigid with respect to the support (i. e., operating-head casing 51), whereas the other cam (i. e., that formed by one cam-surface of cam 92) is movable with respect to the support.

The effect of counterclockwise rotation of shaft will now be discussed, as illustrative of the effect of rotation in either direction. I Follower 64 is reciprocated in the manner disclosed'in "greatlyenlarged Figs. 27m 30. Fig. 27 shows the position of the elements with shaft '58 on dead-center. Figs. 28, 29, and 30 showthe changing position of the elements as the's'haft is rotated counterclockwise: degrees, 40 degrees, and 55 degrees, respectively.

It will be seen from Fig. 28 that, during the first 5 degrees of rotation, actuator-head 65 has moved upward sufficiently to trip the switch located in base 52, shortly thereafter being stopped by shoulders 88, after which all further upward travel of follower 64 is overtravel.

Upward motion of the follower is effected by pressure on the rollers as they are squeezed between the right-hand cam-surface of moveable cam 92 and the cam-surface of left hand fixed earns 83, while the former cam-surface is being moved toward'the latter cam-surface by therotation of shaft 58.

In other words, each cam-surface presses on its respective roller 91 in the direction of radii extending from the points of contact of roller and cam-surface to the axis of the respective roller; and the resultant of these pressures biases follower 64 to move upward against the pressure of helical spring 108, which spring maintains contact between rollers and earns.

It should be noted that the rollers roll on the cams and on each other in the proper rotational direction, with but little slippage and wear.

To analyze the motion of rollers 91 and follower 64 under the influence of the cams, it is convenient to regard the fixed cam-surfaces of left-hand ribs 83 as determining the direction of freedom of motion of the aXes of the rollers, and to regard the rotation of the right-hand camsurface of movable cam 92 about the axis of shaft 58 as imparting the motion to the rollers.

Thus rollers 91 can be regarded as a species of what may be generically termed pressure-transferring means, and the fixed cam surfaces of either one of the two pairs of ribs 83 can be regarded as a species of guide means, and the opposite cam surface of movable cam 92 can be regarded as a species of impelling means; whereby the pressure of the impelling means against the pressure-transferring means causes the latter to move along the path of motion determined by the guide means, thus causing the follower to move upward in opposition to the downward biasing effect of spring 108.

The moving point of contact between the movable cam surface and the surface of the righthand roller, serves as a toggle joint between two lever, arms: (1) the radius of the roller at the point of contact; (2) a line from the center of shaft 58 to the point of contact. The latter lever arm increases in length when the point of contact lies on one of the two flat portions of the movable. camsurface.

Increase in the angle at the toggle joint, serves to drive the rollers away from the axis of shaft 58. So also does the lengthening of the second mentioned arm.

The two cam surfaces are so proportioned and disposed with respect to the rollers, that the combined effect of the two mentioned actions is to cause the movement of the rollers, along their lines of freedom of motion, to be very rapid duringthefirst about 10 degrees of rotation of shaft 58, this movement decelerating thereafter, and becoming almost zero as the lever arms approach toggle in Fig. 30.

The fact that, while the point of contact is on the second straight portion ofthe moveable cam, the direction of travel of this point is practically radial with respect to shaft 58, preventsany cumulation of the two actions from producing acceleration during this period.

Thus far the discussion has related to the motion of the axes of rollers 91, rather than to the motion of follower 64, which is, what is of importance. Deceleration of the latter during the final part of the travel, is accentuated by the change in angle between the .line of motion of the follower and the lines. of motion of the axes of the rollers. For due to the fact that that angle (which is practically the sameas the inclination of carnsurface 83-to the vertical) is about 17 during the first 12 /2 degrees or so of shaft rotation, and about 45 during the rest of the shaft rotation, the velocity of the follower is only about 4 /2% less than the velocity of the roller axes during the first period, whereas it is about 30% less during the rest of its travel.

The rapid initial upward motion of follower 64, followed by deceleration at an increasing rate thereafter, is well illustrated by a comparison of Figs. 27 to 30, which (as already stated) respectively show the positions of the parts with shaft 58 at dead-center, and 5 degrees, 40 degrees, and 55 degrees counterclockwise from deadcenter. For example, the travel of follower 64 is less than half as far during the final 15 degrees of rotation of shaft 58 (Fig. 29 to Fig. 30) than during the first 5 degrees of rotation (Fig. 27 to Fig. 28).

The rapid travel during the first 5 degrees persists, and in fact is somewhat intensified, during the rest of the time during which the first straight portion of cam 92 is in contact with right-hand roller 91 as shown in Figs. 27 and 28: i. e., during about the first 7 /2 degrees of rotation, althought the actuated switch is supposed to be tripped within the first 5 degrees. This ensures a quick trip of the switch, even should the parts of the actuating mechanism become worn.

From about 7 /2 degrees to about 35 degrees, righthand roller 91 is contacted by the first angular point of cam 92.

From about 35 degrees to about 42 /2 degrees, righthand roller 91 is contacted by the second straight portion of cam 92, as shown. in Fig. 29.

And during all the remainder of the rotation, up to 55 degrees as shown in Fig. 30.

We have already seen, during the discussion of the centering mechanism, that rotation of shaft 58 beyond 55 degrees from dead center, is prevented by projection 103 on each of spring-levers 74 striking shoulder 79, see Fig. 5. The contact between cam 92 and right-hand roller 91 has not yet reached toggle between the axis of this roller and the axis of cam 92. If that contact had passed toggle, the downward bias of spring 168 of follower 64 would force the roller to the right and down the curved slope of cam 92, and thus would oppose the centering action of centering spring 76, when the outside stimulus was removed.

The second species of the invention will now be described.

The description of Figs. 1, 2, and 3 is equally applicable to the second species. So also is the description of the centering mechanism, shown in detail in Figs. l9 to 24, and in the squared right-hand end 95 of shaft 58 in Figs. 16 and 17, and shown. assembled in Fig. 5 and in the right-hand portion of Fig. 25.

Operating head casing 111 will now be described, with reference to Figs. 31 to 33, 44 and 45.

The front and rear elevations of this casing appear the same as the rear and front elevations of correspondingd Easing 51 of the first species, as shown in Figs. 5 an Turning now to Fig. 31, the plan view of casing 111, and the two vertical sections thereof, Figs. 32 and 33, it will be seen that 80 are four holes for screws 53, and 81 are two holes for drive screws 55, as in the first SPECIES.

Ledges 113 serve as pivot-seats for the cams, which will be hereinafter described. The sides of recesses 114 serve, at their upper ends, to guide the cams against lateral movement, and these recesses are carried on through to the bottom of casing 111 for no other reason than ease in manufacture. Thesides of recesses 115 serve to guide thefollower 117 which will be hereinafter described.

69 are holes for shaft 118. 71 is a cavity for a bearing 72 hereinafter described, for shaft 111. 73 is a cavity, to hold the entire centering spring assembly, which 9 may be identical to that of the first species, as shown in Figs. and 25.

Figs. 34, 35, and 36 show respectively an edge elevation, a side elevation, and a plan view of follower 117. This follower has four legs 119. In each side there are two aligned slots 120, which serve as bearings for axles 90 of rollers 91, and to permit these axles to slide laterally, so that the rollers can constantly engage each other and the respective cam surfaces, as will be hereinafter described. Not as much lateral play of the axles is necessary in this second species as in the first species, but there is no reason why the slots 120 could not form one continuous slot like 89 of the first species. Each axle is free to slide lengthwise of its roller, as in the first species. When follower 117 is assembled in casing 111, the side wall of each of the two recesses 115 maintain the axles in the rollers.

Figs. 37, 38, and 39 show respectively an edge elevation, a plan view, and a side elevation of cam 116. These cams are two in number.

Sharp edge 121 of the wide portion 122 of each cam 116 serves as a pivot for that cam, as will be hereinafter explained. The lower portion 123 of each cam is slightly narrower than half the width of the wide portion, so as to enable the two narrow portions to cross each other when assembled in the casing.

Hereinafter, so much of one of the wide faces of each cam as lies between the letters H and I will be referred to as the first cam-surface of that cam, and so much as lies on the opposite face between the letters I and K will be referred to as the second cam-surface.

Figs. 40, 41, 42, and 43 show respectively a left-hand end view, a side elevation, a transverse cross-section, and a plan view of shaft 118. 94 is a slot for a screwdriver, as in the first species. 95 is a squared portion, to receive certain elements of the centering spring assembly, as explained with respect to the first species. 125 is another squared portion, which serves as a cam surface to actuate cams 116, as will be hereinafter explained. Fig. 42 may be considered as a cross-section of either squared portion 95 or squared portion 125.

.124 are two grooves in the shaft to receive the legs 119 of follower 117, when assembled, thus locking the shaft in place as will be hereinafter explained.

The assembling of the operating-head mechanism will now be explained, with particular reference to Figs. 44 and 45. Reference will also be necessary to some of Figs. 31 to 43, from time to time.

Shaft 117 is first inserted through holes 69 in casing 111. Bearing 72 and bushing 56 are then applied over the lefthand end of the shaft, and are secured in place by screws 57.

Cams 116 are then inserted, each with its sharp pivot edge 121 resting on one of pivot-seats 113, and with its lower portion crossing over squared portion 125 of shaft 118, as shown in Fig. 45.

Follower 117 is then inserted, legs 119 down, from the top. Its legs will straddle shaft 118, and slide in grooves 124 of the shaft, thus securing the shaft. against longitudinal shift in either direction.

Lever 61 can be secured at any time, as shown in Figs. 1 and 2, and explained in connection with the first species.

The centering-spring assembly is assembled in cavity 73 and is operated, all as explained in connection with the first species, and shown in Figs. 5 and 25.

The final step in assembly is the placing of helical spring 108 and cover plate 54, as explained inconnection with theffirst species.

Follower 117 is reciprocated in the manner disclosed in greatly enlarged Figs. 46 to 49. Fig. 46 shows the position of the elements with shaft 118 on dead-center. Figs. 47, 48, and 49 show the changing position of the elements as the shaft is rotated counterclockwise 5 degrees, 40 degrees, and 55 degrees respectively. These angles. were chosen for these figures, for comparison with corresponding Figs. 27 to.30 of the first species.

Upward motion of follower 117 is effected by pressure on rollers 91 as they are squeezed between the cam-surfaces of cams 116. In other words, each cam-surface presses on its respective roller 91 in the direction of radii extending from the points of contact of roller and camsurface to the axis of the respective roller; and the resultant of these pressures biases follower 117 to move upward against the pressure of helical spring 168, which spring maintains contact between rollers and earns.

As in the first species, the rollers roll on the cams and .On each other in the proper rotational direction, with but little slippage and wear.

Although in this second species the rollers are squeezed between two movable cams 116 moving toward each other, as contrasted with the first species, in which the rollers are squeezed between a fixed cam 83 and a movable cam 92 moving toward it; yet in both species there is relative movement of the cam-surfaces toward each other. Furthermore, in the second species, either one of the two cams 116 can be regarded as prescribing the direction of freedom of motion of the axes of the rollers, and the other of these two cams 116 can be regarded as imparting the motion to the rollers.

Thus, as explained in connection with rollers 91, fixed cams 83, movable cam 92, and spring 108, of the first variant: rollers 91 of the second variant can be regarded as pressure-transferring means, the upper cam-surface of either one of the two cams 116 can be regarded as guide means, and the upper cam-surface of the other cam 116 can be regarded as impelling means.

The two cams 116, by virtue of crossing each other, have a sort of scissors action. The two cam-surfaces which engage the rollers, face each other. There are also two second cam-surfaces, which face each other and embrace squared portion of shaft 118.

As shaft 118 rotates in either direction (counterclockwise rotation being shown in Figs. 46 to 49), the squared portion acts as a cam, to spread the lower ends of the two cams 116 apart, and thus move the first cam-surfaces toward each other. The points of contact between shaft 118 and the second (i. e., lower) cam-surfaces of cams 116, are initially two corners of squared portion 125; and these points of contact move in a circular are about the axis of the shaft. The component of each of these motions which tends to push the respective cam-surface away from the other is perpendicular to the cam-surface, and this component becomes less and less. Thus in rotating through the first 5 degrees (i. e., from Fig. 46 to Fig. 47) the spreading component is about 75% of the motion of the point of contact. Whereas in Fig. 48 the spreading component of the left-hand point is practically zero, and of the right-hand point is negligible. And in Fig. 49 both components are zero.

There will now be discussed the effects of the difference in length and direction of the respective lever-arms of the two cams 116, with respect to squared surface 125 of shaft 118. Each such lever-arm extends from the pivot-edge 121 of the cam to the point of contact of shaft 118 with the cam. These differences appear to be considerable in vFig. 47, and it might be thought that this would introduce considerable asymmetry of motion of the two cams.

But such is not the case. For the two differences have a very nearly offsetting elfect, as will be seen by comparing the positions of the lower ends of the two cams 116 in each of Figs. 46 to 49. Thus the motion of the two cams, as well as their configuration, is practically symmetrical.

Although, on each cam, the upper cam-surface is on the opposite side of the cam from the lower cam-surface,

yet the cross-over of the two cams, scissors-fashion, causes the two upper cam-surfaces to face each other, and like wise the two lower cam-surfaces. So the spreading-apart of the twolower cam-surfaces causes the two upper camsurfaces to approach each other. 7 I

The positioning of the cam-pivots 121'above thejcrossover point and laterally spaced from each other' (-instead of at the cross-over point, as would be expected in a scissors mechanism) causes the angle between the two upper earn-surfaces to increase as these two surfaces approach each other (rather than to decrease as would be expected in a scissors action).

This change in angle causes the upward motion of the rollers to decelerate, in proportion to the movement of the cams. And, as already seen, the movement of the cams decelerates to zero, in proportion to the rotation of shaft 118 from dead-center. Thus these two effects cumulate to cause the upward movement of the rollers, and hence of follower 117, to be very rapid during the initial rotation of shaft 118,-this'movement decelerating thereafter, and becoming zero as the elements assume the position of Fig. 49.

The already mentioned practical symmetricality of the motion of the upper cam-surfaces of the two symmetrical cams 116, prescribes a path of'motion for the rollers nearly identical to the path of motion of follower 117 that the rate of travel of the follower is indistinguishable from that of the rollers. The slight departure from vertical of the path of therollers is easily talr'en-up by the already mentioned looseness of their bearings.

The amount of travel of follower 117 during the early degrees of rotation of shaft 118 from dead center, can be adjusted, while still decelerating to zero at 55 degrees, by changing the initial angle between the upper cam-surfaces of cams 116, or at least the initial angle between the lower portion of those surfaces. The smaller this angle, the sharper will be the initial rise of the follower.

There is no passing through toggle analogous to that described in connection with the first species. Thus shoulders 79 (see Fig. Sidescribed as preventing passing through toggle in the first species of the. invention, are not necessary for that purpose in the second species. But they are useful in preventing undue strain on centering spring 76, though they might be omitted if further overtravel were desired for any reason.

The first species represents the best mode now contemplated by the inventor of carrying out his invention. The second species,-although perhaps more simple to understand, and slightly less expensive tomanufaeture, is not only less easy to assemble, but also its cams 116 are less easy to make uniform. These cams are stamped out, and then formed. Forming them is not difficult, but the thickness of the stock from which they are formed is apt to vary beyond tolerance. Also the scraping of the corners of squared portion 125 of shaft 118 on the lower cam-surfaces of cams 116 causes wear; no such cause of wear exists anywhere in the first species, specimens of which have undergone as many as twenty-fivernillion complete reciprocations, eachwi'thout discernable wear on any of the parts.

However, the second species, although not preferable to the first species, is quite acceptable.

It will be readily evident from the foregoing description that the invention affords a novel and useful conversion mechanism, by which the rotary reciprocation of an externally actuated rotary member can be converted into translation of a member which is used to actuate some other mechanism.

Now that two embodiments of the invention havebeen shown and described, and several variations therefrom have been suggested, it is to be understood that the invention is not to be limited to the specific forms or arrangements of parts herein shown and described.

What is. claimed is: p I p I. In an actuating mechanism, the combination comprising: a support; an externally actuable rotatable member mounted on the support for limited rotation backand-forth with respect to the support;'a follower slidably mounted on the support for substantially linear reciprocation with respect thereto, for output of linear motion; and means for converting the rotary motion of the rotatable member into translation of the follower, said converting means comprising: means biasing the follower to translate in one given direction; a pair of interengaging rollers journaled on the follower side by side laterally with rspect thereto; and at least one pair of cams carried by the support with their cam-surfaces facing each other, each surface rollably engaging one of the rollers and relatively movable toward each other in response to the rotation of the rotatable member, the two cam-surfaces having such conformations and being so disposed relative toeaeh other and to the rollers that as the two camsurfaces are moved toward each other the resultant of the pressures of the two cam-surfaces on their respective rollers will translate the follower in opposition to the biasing means.

2. Mechanism according to claim 1, wherein the two cam-surfaces have such conformations and are so disposed relative to each other and to the rollers that, as the two cam-surfaces are moved toward each other, uniform velocity of the rotatable member will at first be converted into rapid translation of the follower which translation will be speedily decelerated thereafter.

3. Mechanism according to claim 1, wherein the rollers are loosely journaled, to ensure contact between them and between each roller and its respective cam-surface under pressure of the cam-surfaces.

4. Mechanism according to claim 1, wherein one cam of the pair of cams is held rigid with respect to the support, the other cam being moveable with respect to the support.

5. Mechanism according to claim 4, wherein the moveable cam is held rigid with respect to the rotatable member and rotates with the latter.

6. Mechanism according to claim 5, wherein there are two pairs of cams, each pair having the recited characteristics, one of which pairs of cams engages the two rollers when the rotatable member is rotated in one direction from dead center, and the other of which pairs of cams engages the two rollers when the rotatable member is rotated in the opposite direction from dead center.

7. Mechanism according to claim 1, wherein one cam of the pair of cams is held rigid with respect to the support, the other cam being movable with respect to the support, and wherein the rollers are freely shiftable laterally with respect to the follower member to enable the rollers to interengage and to enable the roller which engages the surface of the rigid cam to continue to so engage.

8. Mechanism according to claim 7, wherein there are two pairs of cams, each pair having the recited chara'cteristics, one of which pairs of cams engages the two rollers'when therotatable member is rotated in one direction from dead center, and the other of which pairs of cams engages the two rollers when the rotatable member is rotated in the opposite direction from dead center.

9. Mechanism according to claim 1, wherein the two cam surfaces are symmetrical with respect to the centerline of the follower member.

10. Mechanism according to claim 9, wherein both cams are separately pivoted on the support at points remote from the pivot-axis of the rotatable member and spaced from each other laterally across the path of the follower. a

11. Mechanism according to claim 10, wherein the cam surface on each of the two cams is adjacent its pivot; and each cam crosses over the other at a mid point; and each cam has a second cam surface beyond the cross-over point, said two second cam surfaces facing each other; and the rotatable member passes between said two second cam surfaces and has a cam surface operationally engaging said two second cam surfaces.

12. Mechanism according to claim 11, wherein the two second cam surfaces and the cam surface of the rotatable member have such conformations and are so disposed that, as the rotatable member is rotated in either direction from dead center, the cam surface of the rotatable member will spread apart the two second cam-surfaces, thus moving the two first cam-surfaces toward each other.

13. Mechanism according to claim 12, wherein the two second cam surfaces and the cam surface of the rotatable member have such conformations and are so disposed that, as the rotatable member is rotated in either direction from dead center, uniform angular velocity of the rotatable member will be converted into increasing the angle between the two first cam'surfaces at a decreasing rate.

14. In an actuating mechanism, the combination comprising: a support; an externally actuable member, mounted on the support for limited rotation back-andforth with respect thereto; a follower mounted on the support for substantially linear reciprocation with respect thereto; means biasing the follower to move in one given direction; pressure-transferring means mounted on the follower for motion therewith and transversely with respect thereto; guide-means engaging the pressure-transferring means for prescribing the path of said motion thereof; and impelling means shiftable toward the guide means by the rotation of the externally actuable member and engaging the pressure-transferring means, for moving the pressure-transferring means along its said path of motion and thereby causing the follower to move in opposition to the biasing means at velocities predetermined by the configuration and relative location of the recited 30 elements.

15. In an actuating mechanism, the combination comprising: a support; an externally actuable rotatable member, mounted on the support for limited rotation baclo and-forth with respect to the support; a follower slidably mounted on the support for reciprocation with respect thereto for output of substantially linear motion; means restricting the reciprocation of the follower to a substan tially linear path; means biasing the follower to translate in one given direction; a pair of interengaging rollers journaled on the follower side by side laterally with respect thereto in such manner as to be moveable longitudinally therewith and laterally with respect thereto; guide means consisting of a camway engaging one of the rollers, for prescribing the paths of motion of the rollers; a moveable cam shiftable toward the guide means by the rotation of the rotatable member and engaging the other of the rollers, for imparting motion to the rollers along their prescribed paths of motion and thereby imparting motion to the follower in opposition to the biasing means.

16. Mechanism according to claim 15, wherein the moveable cam is rigidly attached to the rotating member and imparts motion to the roller which it engages by means of toggle action at the line of contact between the moveable cam and the roller which it engages.

17. Mechanism according to claim 16, wherein there is stop means for automatically preventing said line from passing through toggle.

References Cited in the file of this patent UNITED STATES PATENTS 2,681,221 Randol June 15, 1954

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