US3177975A - Linear control mechanism - Google Patents

Description

April 13, 1965 J. GALLI 3,177,975

LINEAR CONTROL MECHANISM Filed Deo. 21. 1961 INVENTOR.' JOSEPH GALLI United States Patent O 3,177,975 LlNEAR CONTROL MECHANISM Joseph Galli, Chicago, Ill., assignor to Webcor, Inc., Chicago, Ill., a corporation of Illinois Filed Dec. 21, 1961, Ser. No. V161,079 Claims. (Cl. 185--37) This invention relates in general to control mechanisms and in particular to a linear control mechanism suitable for use in mechanical timers to provide substantially equal time increments over the operating range of a timer.

Mechanical timer mechanisms utilize a bias element to create the necessary force for actuation or rotation. Bias members have taken various forms in the multitude of timer mechanisms existing today, varying from a fine helical Watch spring to a rugged iat leaf spring. In addition, other resilient members, varying from a simple rubber band to a line steel torsion bar, have found effective use in the actuation of timing mechanisms.

A simple, inexpensive, compact commercial mechanical timing device is frequently mounted in a system to actuate a component or a switching unit. Considerable utilization of a small compact mechanical timer has been -found in military explosive devices as a means for controlled detonation.-

Heretofore, a timer, having the characteristics just described, generally utilized an elongated coil spring interconnected with `a train of gears to elect rotation of a member to a predetermined position which would release or actuate a coordinating member. To impart rotation to the train of gears, the coil spring is placed in tension lby elongation, generally by causing one end of the spring to .be drawn around a circular member While the other end is anchored to a portion of the timing device.

One of the greatest shortcomings of these prior mechanical timer mechanisms is the non-'linearity of time increments over the operating range of .the timer. It is read-ily understood that the spring member will exert its greatest force at the point of greatest elongation, up to a certain point, and subsequently diminishes in force as the spring moves towards its normal retracted position of rest. Thus, the force of the spring will move the train of gears into faster rotation at the point of greatest elongation and substantially slower as it approaches the position of rest. The variable force of the spring crea-tes unequal time intervals over the full range of the timer.

l-t is therefore the primary object of this invention to provide an improved linear control mechanism for use in mechanical timers which eliminates the shortcomings of prior mechanisms of this character and provides substantially uni-form time increments over the operating range of the timer.

A specic object of this invention is to provide an improved linear control mechanism utilizing a contoured cam about which a spring member is secured to effect uniform rotation of a train of gears.

Another object of this invention is to provide a contoured cam in combination with a gear train of a mechanical timer wherein an elongated coil spring, under tension, is disposed and secured to the cam to exert a substantially equal force on the gear train throughout the operating range of the timer as the spring is rateably removed frorn the cam.

A still further object of this invention is to provide an improved linear lforce control device to uniformally change the for-ce of an elongated coil spring under tension into a smooth uniform rotation of a journaled member.

Other objects .and advantages of the present invention will be apparent from the following specifi-cation, claims and drawings, in which:

FIG. l is a top pl-an view of a mechanical timer incorporating the control mechanism of this invention;

FIG. 2 is an elevational View showing one side of the timer shown in FIG. l;

FIG. 3 is an elevational view showing the other side of the timer shown in FIG. l with a releasable member shown in the open position; and i FIG. 4 is an enlarged, fragmentary partially sectioned plan view illustrating the relationship of the components of the linear control mechanism as mounted in the timer.

By way of a brief explanation, for a better understanding of the detailed description to follow, the invention is yprimarily characterized by the use of a cam member for securement and receipt or" a coil spring which, when in tension, will cause rotation of a train of gears to operate a timer. The contour of the cam increases in height in the direction of rotation for elongation or tensioning of the coil spring. The cam contour permits the spring tf-orce to remain substantially constant throughout the period of timer operation, thus permitting equal time increments over the full operative range of the timer.

It is to be understood that the control mechanism of :this invention is illustrated in the drawings and described in the specification in conjunction with a mechanical timer only by way of example and that the principle of uniform force from a coil spring as described for this invention may be readily utilized in other devices. y.

Referring now to the drawings and more specifically to FIGS. l, 2 and 3, a thin compact mechanical timer 10 is illustrated in which the control mechanism of this invention is mounted. The timer lil, having a substantially open rectangular coniiguration, provides parallel upper and lower walls 12 and'14 respectively which are secured in spaced apart relationship by spacers 16 disposed at the four corners thereof.V y

A conventional gear train, indicated generally by the numeral 18, is rotatably mounted between the two walls 12 and 14 to provide timer rotation of a shaft 20.

Referring now more specifically to FIGS. 2 and 3, the shaft 20 has an upper portion 22, of reduced diameter, which extends up through and to an elevation well above the upper Wall 12. A lower portion 24 of the shaft 20 carries one of the gears of the gear train 18, a conventional friction clutch arrangement 26 and a contoured cam 28.

A spring actuating arm 30 is releasably mounted on the upper wall 12 with an end 32 of arm 30 hooked over and engaging the edge of wall 12. An aperture 34, centrally disposed in an elongated slot 36, is formed through the other end 38 of the arm 30 in juxtaposition with the end of the shaft 20, as best seen in FIG. 1. A hold down bearing pin 40 is secured through the shaft 20, transverse to the axis thereof. Thus, when the shaft 20 is rotated 3,177,975 Patented Apr. 13, 1965 t suiciently to orientate the pin 40 with the slot 36 in the arm 30, the spring arm 30 is released, the resiliency of arm 30 moving it upwardly away from the shaft 20 as seen in FIG. 3.

With the spring arm 30 disposed over the shaft 20 and the shaft 20 rotated suiiiciently, the hold down bearing pin 40 will retain the arm 30 in position until pin 4l? is subsequently orientated with the slot 30 in a manner to be described.

The bias or operating means of the timer is an elongated spiral coil spring 42 having an end 44 secured to one of the spacers 16, as best seen in FIG. 3, and the other end 46 secured to an anchor pin 48 mounted in the surface of the cam 28, as best seen in FIG. 4.

Referring now more specifically to FIG. 4, the spring 42 is elongated by the rotation of the shaft 20 causing the spring to wrap around the surface of cam 28. Rotation of the shaft r20 is easily accomplished by a suitable key (not shown) adapted to fit over the end of shaft 26 and the pin 40. As shaft 20 is rotated, the gear train 18 is held stationary through the action of the friction clutch arrangement 26. On release of the key, after rotating the shaft 20, a release pin 45, passing through the timer and engaging the teeth of one of the gears of gear train 18, is removed so that the force created in the spring, due to elongation, Will rotate the shaft 20 in the opposite direction of elongation, as shown by the arrow in FIG. 4. The spring will cause rotation of the shaft 20 to a point sufhcient to orientate the pin 40 with the slot 35 in spring arm 30. As the spring arm 30 is released, the force or movement thereof is utilized to actuate a switch or move a component part.

As best seen in FIG. l, equally spaced time increments 50, may be marked on the upper surface of spring arm 30 about the slot 36 to aid in setting the timer for the desired time interval.

As illustrated in FIG. 4, the cam 28 provides a contoured surface of increasing height in the direction of elongation of the spring 42. It being readily understood that the force of an elongated spring, under tension, progressively diminishes as the amount of elongation decreases; the cam 28 utilized in this invention permits equal rotation of the shaft-20 with less reduction in spring elongation than the conventional circular cam. Thus, the force of the spring 42 is maintained at a more constant rate to drive the gear train 18 at a substantially uniform speed.

It is therefore readily apparent to those skilled in the art, that the contour of the cam will retain the spring in elongation for a greater period of time, or for a substantial increase in amount of rotation of the shaft to which the cam is connected to provide substantially equal time increments over the operating range of the timer.

It will be understood that certain changes in detail may be resorted to Without departing from the field and scope of the invention and it is intended that all such variations be included, as fall within the scope of the appended claims, in this application, in which the preferred form only of the invention has been disclosed.

What is claimed is:

1. In combination with a mechanical timer having a train of gears rotatablydisposed therein, a linear control mechanism comprising a shaft journaled Within the timer, said shaft having a gear secured thereon in mesh with a gear in said train of gears for timer rotation of said shaft, a spring actuated member mounted for movement between two positions in one of which it is to be restrained, means carried by said shaft for restraining said spring actuated member in said one of its two positions and releasing said member in one position of relative rotation of said shaft, a cam member having contoured surface secured to the shaft, and an elongated spiral coil spring positioned rwithin the timer having one end thereof anchored to the timer and the other end secured to the cam for the spring coils to flex around the cam, said shaft rotated in one direction to effect elongation of said spring about the contoured Cil surface of the cam, said contoured surface increasing in height inthe direction of elongation of the spring to maintain a constant force in tension in the spring and uniformly rotate said shaft in the other direction to said one position thereof for a large period lof time under the control of said timer to release said member.

2. A mechanical timer comprising spaced apart upper and lower walls, a train of gears rotatably disposed between said walls, a shaft journaled within the timer having an end thereof extending upwardly past the upper Wall, said shaft having a gear secured thereon in mesh with a gear in said train of gears, a spring arm having one end hingedly secured on an edge of the upper wall, and the other end releasably secured over the extended end of said shaft, a cam member 4secured to the shaft, and an elongated spiral coil spring positioned within the timer having one end thereof anchored to the timer and the other end secured to the cam for the spring coils to iiex around and Contact the cam, said shaft rotated in one direction to wrap said spring about the cam to create a force in the spring to rotate said shaft in the other direction a predetermined distance to release said spring arm.

3. A mechanical timer comprising spaced apart upper and lower Walls, a train of gears rotatably disposed between said walls, a shaft journaled within the timer having an end thereof extending upwardly past the upper wall, said shaft having a gear secured thereon in mesh with a gear in said train of gears, a spring arm, means releasably securing said spring arm over the extended end of said shaft, a contoured cam member secured to the shaft, and a coil spring positioned within the timer having one end thereof anchored to the timer and the other end secured to the cam, said shaft rotated in one direction to effect elongation of said spring about the contoured cam to create a force in tension to rotate said shaft in the other direction -a predetermined distance to release Said spring arm and timer means actuated by said shaft under the tension of said spring for controlling the rotation of the shaft.

4. A mechanical timer comprising spaced apart upper and lower walls, a train `of gears rotatably disposed between said walls, a shaft journaled within the timer having an end thereof extending upwardly past the upper wall, a bearing pin secured in the extending end of said shaft at right angles to the axis thereof, a spring actuating arm having one end hingedly secured on the upper wall, a centrally disposed slot formed in the other end of the spring arm received over the extended end of said shaft and bearing pin, said shaft having a gear secured thereon in mesh with a gear in said train of gears, a cam member secured to the shaft, and an elongated spiral coil spring positioned within the timer having one end thereof anchored to the timer and the other end secured to the cam, said shaft rotated in one direction to wrap a portion of the coils of said spring about the cam to create a force in tension in the spring and to effect misalignment of said bearing pin with the slot in said spring arm to resiliently retain said spring` arm therebelow, said force of tension in the spring reacting upon the cam and causing rotation of the shaft in the other direction to align said bearing pin with said slot releasing said spring actuating arm.

5. A mechanical timer comprising spaced apart upper and lower walls, a train of gears rotatably disposed between said walls, a shaft journaled within the timer having an end thereof extending upwardly past the upper wall, a bearing pin secured in the extending end of said shaft at right angles to the axis thereof, said shaft having a gear secured thereon in mesh with a gear in said train of gears, a spring actuating arm having one end hingedly secured on the upper Wall, 4a centrally disposed slot formed in the other end of the spring arm received over the extended end of said shaft and bearing pin, a cam member having a contoured surface secured to the shaft, and a coil spring positioned within the timer having one end thereof anchored to the timer and the other end secured to the contoured surface of the cam, said shaft rotated in one direction to Wrap said spring on to said contoured surface of the cam electing elongation of the spring to create a force in tension and to eect msalgnment of said bearing pin with the slot in `said spring actuating arm to resiliently retain said spring arm therebelow, said contoured surface of the cam increasing in height in the direction of elongation of the spring maintaining a substantially constant force of tension in the spring for uniform Totation of the shaft in the other direction to align said bearing pin with said slot whereby said spring actuating arm will be released.

References Cited by the Examiner UNITED STATES PATENTS 2,119,335 5/38 LeTourneau 185-37 2,178,122 10/ 39 Astler 267-1 2,327,509 8/43 Daily 185-1 2,661,815 12/53 McGay 185-38 2,935,160 5/60 Lawson 18S-40 2,947,019 8/ 60 Liesse 267-1 10 JULIUS E. WEST, Primary Examiner.

ANDRES H. NIELSEN, EDGAR W. GEOGHEGAN,

Examiners.

Claims (1)

1. IN COMBINATION WITH A MECHANICAL TIMER HAVING A TRAIN OF GEARS ROTATABLY DISPOSED THEREIN, A LINEAR CONTROL MECHANISM COMPRISING A SHAFT JOURNALED WITHIN THE TIMER, SAID SHAFT HAVING A GEAR SECURED THEREON IN MESH WITH A GEAR IN SAID TRAIN OF GEARS FOR TIMER ROTATION OF SAID SHAFT, A SPRING ACTUATED MEMBERS MOUNTED FOR MOVEMENT BETWEEN TWO POSITIONS IN ONE OF WHICH IT IS TO BE RESTRAINED, MEANS CARRIED BY SAID SHAFT FOR RESTRAINING SAID SPRING ACTUATED MEMBER IN SAID ONE OF ITS TWO POSITIONS AND RELEASING SAID MEMBER IN ONE POSITION OF RELATIVE ROTATION OF SAID SHAFT, A CAM MEMBER HAVING CONTOURED SURFACE SECURED TO THE SHAFT, AND AN ELONGATED SPIRAL COIL SPRING POSITIONED WITHIN THE TIMER HAVING ONE END THEREOF ANCHORED TO THE TIMER AND THE OTHER END SECURED TO THE CAM FOR THE SPRING COILS TO FLEX AROUND THE CAM, SAID SHAFT ROTATED IN ONE DIRECTION TO EFFECT ELONGATION OF SAID SPRING ABOUT THE CONTOURED SURFACE OF THE CAM, SAID CONTOURED SURFACE INCREASING IN HEIGHT IN THE DIRECTION OF ELONGATION OF THE SPRING TO MAINTAIN A CONSTANT FORCE IN TENSION IN THE SPRING AND UNIFORMLY ROTATE SAID SHAFT IN THE OTHER DIRECTION TO SAID ONE POSITION THEREOF FOR A LARGE PERIOD OF TIME UNDER THE CONTROL OF SAID TIMER TO RELEASE SAID MEMBER.

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