US3308672A - Switch closure mechanism - Google Patents

Description

March 1%? R. w. PATRKZK ETAL 3,38,i2

SWITCH CLOSURE MECHANISM 5 Sheets-Sheet 1 Filed March 12, 196

March M, 16? R. w. PATRICK ET AL. 3,308,72

SWITCH CLOSURE MECHANISM 3 Sheets-Sheet 2 Filed March 12, 1965 INVENTOR. Run/mu: LJILLH -H PATRIML 43ml 'RKHAR BY March 14, 1967 Filed March 12, 1965 R. W. PATRICK ETAL SWITCH CLOSURE MECHANISM 3 Sheets-Sheet 3 V EN TOR.

IN RKHARD WILLIAM P 'Egvce 'Rmmxmv M: Fpwaeo United States Patent 3,308,672 SWITCH CLOSURE MECHANISM Richard William Patrick, New Cumberland, and Bruce Richard McFadden, Harrisburg, Pa., assignors to AMP Incorporated, Harrisburg, Pa.

Filed Mar. 12, 1965, Ser. No. 439,405 7- Claims. (Cl. 74-89) This invention relates to an improved closure mechanism for multiple electrical switches, particularly of the type utilized to read data cards.

US. application Serial No. 296,812, filed July 22, 1963, describes a new card reader assembly which employs an angular closure technique to develop a wiping contact under increasing wedging pressure. In application Serial No. 400,011, filed Sept, 29, 1964, there is described an improvement to the card reader of Serial No. 296,812, related to changes which simplify construction and provide a backwipe of contacts to better assure completion of circuits in low voltage applications.

It is an object of the present invention to provide an improved drive mechanism for multiple switches of the types disclosed in the above mentioned applications and to provide a drive mechanism applicable with multiple electrical switches in general wherein there is a closure of contacts under increasing wedging pressure. It is a further object of the present invention to provide a rugged and inexpensive mechanism for manually operated multiple switch devices which inherently assured a full closure and overtravel of contact surfaces.

In electrical switches which include a type of contact closure wherein non-resilient contact surfaces are driven against resilient contact surfaces, the displacement-force characteristics to effect complete closure generally begin with a low value and then increase rather sharply and continuously to the end of the closure cycle. Because of this the operator of such devices must exert an ever increasing force against the operating mechanism. Psychologically this is bad and practically it tends to cause improper closure; the operator stopping at some point before the full closure cycle is completed. The present invention features a driving mechanism including a series of lever arms linked in a manner to develop an ever increasing mechanical advantage which is caused to approach infinity in the last part of the closure cycle. Additionally, the driving mechanism contemplated by the invention is so arranged that the driving force throughout the complete cycle is in a constant direction, terminated by a fixed stop position to lock further travel only after the driving stroke has been completed.

In the drawings:

FIGURE 1 is a perspective of the multiple switch assembly of the invention embodied in a card reader device;

FIGURE 2 is a perspective of the drive mechanism of the device of FIGURE 1;

FIGURES 3-6 are plan views showing the operating linkage of the drive mechanism at various positions throughout a complete stroke or cycle of operation; and

FIGURE 7 is a plot of force vs. displacement included to explain the operation of the linkage of the invention.

Referring now to FIGURE 1, the assembly 10 represents what is known as a static card reader. It is the function of the device to receive a data card having holes punched therein and to read such card by developing electrical signals on leads associated with the presence of such holes. The assembly 10 includes a base 22, and a drawer 30 which is adapted to be driven from an open position to the closed position shown to carry the data card into engagement with a series of contact spring members under increasing wedging pressure. This results in the spring members penetrating available card holes to contact printed circuit pads disposed on the upper face of 30.

Reference is made to the above mentioned applications for a detailed description of this operation,

The various movements of the drawer are controlled by an operating handle here shown as 40 which is pulled out to the position shown by the dotted line to open the drawer and is pushed in to the position shown solidly to close the drawer to effect reading.

The driving mechanism shown in perspective in FIG- URE 2 includes a bracket 42 afiixed to the side of the reader base 22. This bracket is generally U shaped and includes a cover plate 44 which is positioned to cover the driving mechanism as indicated in FIGURE 1. In the arms of bracket 42 are apertures 46 adapted to support the sliding movement of the driving mechanism and contain the drive train and linkage which is comprised of a shaft 48 links 50 and 52 which are tied thereto and further to a shaft 54. Rotary movement of the shaft 54 operates to drive the reader drawer 30 in and out of the assembly described in the above mentioned applications.

As will be discerned from FIGURES 3 and 4, there is provided in the center region of shaft 48 a recess 49 which serves to accommodate the volume of link 50 when the operating mechanism is in the outward position with the drawer 30 of assembly 10 open. At the outer end of the recess 49 is a pin member shown as Sila which projects outwardly of the diameter of the shaft 48 to limit outward movement of the handle 40 and the shaft 48. At the opposite end of St the link is bifurcated to accommodate the upper end of shaft 52 which is tied thereto for pivotal movement by a pin shown as 520.

Surrounding shaft 48 proximate the outer leg of bracket 42 is a compression spring 58 which serves to drive the shaft 48 inwardly by an engagement with 50a as shown in FIGURE 3. This rotates shaft 54 in a clockwise sense to operate the card ejector mechanism to a retracted position and prepare the assembly to receive a new card. The need for this feature and the structure related thereto should be apparent from the previously mentioned applications. In the bracket leg opposite thereto is a set-screw shown as 60 which may be adjusted to act as a stop for limiting inward travel of the driving mechanism by engaging the top or right hand surface of link 50.

Referring now to the operation of the invention and to FIGURES 36, the various positions of the drive mechanism are shown for a complete cycle. In FIGURE 3 the handle and operating mechanism is in a position such that the drawer of assembly It) is fully open and ready to receive a card. In FIGURE 4 the mechanism is in a position of partial closure and in FIGURE 5 the mechanism is in a position of almost complete closure. FIGURE 6 depicts the mechanism in complete closure at the full end of the closure cycle. In FIGURE 7 there is a plot of force versus displacement made up from a test of an actual unit with the upper plot representing the actual force to push the drawer throughout the cycle shown in FIGURES 3-6 and the lower plot B showing the force applied to the handle 40 throughout the same cycle. The relative position of the operating mechanism is depicted in FIGURE 7 by reference at the various points A, B, C and D. related respectively to FIGURE-S 36. As will be apparent the first movement of the handle 40 is rior to engagement of the contact springs of the assembly and represents only frictional sliding force including the frictional components of the drawer and of the driving linkage. In the position of FIGURE 4 or at A, the linkage has begun to encounter the additional forces required to deflect the contact springs of the assembly which as indicated increases rapidly and constantly thereafter. The applied force required, however, increases only slightly due to the increasing mechanical advantage achieved through the linkage. With the linkage as posi- 3 tioned in FIGURE 5 or at C, this mechanical advantage begins to approach infinity even though the force required to close the drawer against the compression of the contact springs has increased substantially in an opposite direction.

The increase in mechanical advantage thus means that the final length of the stroke of closure up to the linkage position shown in FIGURE 5 the force actually required is insubstantial and the force required for final closure to the position shown in FIGURE 6 or at D, is in the same direction and constantly decreasing. Because of this the operator exerting the force shown approaching 10 pounds at the position of the linkage shown in FIG- URE 5 is induced to complete the stroke for the last few thousandths of an inch at a decreasing force. Furthermore, since the force required is in the same direction the operator is not likely to stop before full closure is completed.

As the linkage passes from the position of FIGURE 5 to the position of FIGURE 6, the rotation of shaft 54 reverses thus developing a baclewipe of the contact springs. During this backwipe the springs unload and tend to aid in the continued travel of the linkage.

From the foregoing it should be apparent that through a relative simple linkage mechanism a highly desirable cycle of closure for multiple contact spring devices may be readily afiected which physically and psychologically tends to encourage proper operation. It is contem lated that the invention may have utility in other devices having the same general closure requirements.

Having described our invention in a manner intended to enable its practice in a preferred mode we now define it through the appended claims.

What is claimed is:

1. A drive mechanism for providing a controlled rotary movement, a driven shaft to operate an electrical switch, a base supporting said driven shaft for rotary movement, support means attached to said base supporting a second shaft for linear movement, said support means including means to limit said second shaft linear movement between a first and a second position, a linkage connecting said driven and second shafts, said linkage including a first link rigidly secured to said driven shaft and a second link pivotally connected to said first link and to said second shaft, the said linkage being positioned and having points of connection relative to said shafts so as to provide an increasing mechanical advantage as said second shaft is displaced from said first to said second position to a point wherein the force required to displace said second shaft as it approaches the said second position is less than the force required to initiate displacement of said second shaft from said first position whereby to better assure completion of movement and switch operation.

2. The mechanism of claim l wherein said linkage is positioned and includes points of connection to said driven shaft so that a continuous one stroke movement of said second shaft between said first and second positions causes a substantial'rotation of said driven shaft in one direction and then a slight rotation of said driven shaft in an opposite direction.

3. In a drive mechanism for providing a controlled closure for switch contacts, a switch base, a bracket secured on the side thereof, a driving shaft supported in said bracket for sliding push-pull movement along a given axis, means limiting said movement between first and second positions, a driven shaft supported for rotary movement in said base with the axis thereof transverse to the said given axis, a first lin k fixed to said driven shaft and a second link pivotally connected to said first link and pivotally connected to said driving shaft, the said links being connected to each other and to said shafts at points to provide a mechanical advantage which increases as said driving shaft is displaced from said first position toward said second posi-. tion and further including a connection to each other and to said shafts at points to provide a first rotation in a given direction of said first shaft and then a reverse rotation of said first shaft responsive to movement of said second shaft positively in one direction whereby to assure switch operation.

4. In a drive mechanism for providing a controlled closure of switch contacts, a switch base, a driving shaft positioned and secured thereon for sliding movement and including a handle positioned for manual push-pull operation, a driven shaft secured in said base for rotary movement to effect switch operation, a linkage connecting said driving shaft to said driven shaft including links positioned relative to said shafts and connected thereto at points to effect a rotary drive of said driven shaft responsive to manual displacement of said driving shaft with the force required to effect a displacement of said shaft increasing during a first period of displacement and then decreasing during a second portion of displacement whereby to better assure switch operation by including a completed displacement of said shafts.

5'. In a drive mechanism for manual closure of electrical contacts, a contact housing, a driven shaft supported for rotary movement to effect contact closure, :1 driving shaft having an operating handle thereon positioned for manual use and means on said housing supporting said driving shaft for linear movement, means for limiting movement of said driving shaft between said first and second positions, a linkage connecting said driving shaft to said. driven shaft, said linkage being connected at points on said driving shaft and said driven shaft and being positioned to provide a mechanical advantage which increases as said driving shaft is displaced from said first toward said second position so that the force required to displace said driving shaft and said driven shaft is reduced in the last portion of shaft movement.

6. In a drive mechanism for electrical switch operation, a switch housing, a bracket attached to the side thereof having vertically disposed legs, apertures in said legs positioned to receive and support a driving shaft, said driving shaft having a handle thereon positioned for manual use, a driven shaft supported for rotary movement in said base and positioned between said legs, a linkage positioned between said legs connecting said driving shaft to said driven shaft, said linkage being connected between said shafts and positioned whereby to provide rotation in one direction of said driven shaft during a first displacemerit of said driving shaft and then rotation to an opposite direction of said driven shaft responsive to further displacement of said driven shaft in the same direction.

7. The mechanism of claim' wherein said driving shaft has a slot therein of a size to receive the body of a portion of said linkage as said mechanism is operated whereby to reduce the overall size of said mechanism relative to said switch device.

References Cited by the Examiner V UNITED STATES PATENTS 2,473,848 7/1949 Baxter 2001 68 2,830,759 4/1958 Hudes et a1 23561 2,918,275 12/1959 Arlauskas 74-105 X 3,066,863 12/1962 Wilson a- 200-46 X 3,148,251 9/1964 Burke 200--46 3,156,793 11/1964 Rosen et al 20046 BERNARD A. GILHEANY, Primary Examiner.

H. E. SPRINGBORN, T. MACBLAIN,

Assistant Examiners.

Claims (1)

1. 4. IN A DRIVE MECHANISM FOR PROVIDING A CONTROLLED CLOSURE OF SWITCH CONTACTS, A SWITCH BASE, A DRIVING SHAFT POSITIONED AND SECURED THEREON FOR SLIDING MOVEMENT AND INCLUDING A HANDLE POSITIONED FOR MANUAL PUSH-PULL OPERATION, A DRIVEN SHAFT SECURED IN SAID BASE FOR ROTARY MOVEMENT TO EFFECT SWITCH OPERATION, A LINKAGE CONNECTING SAID DRIVING SHAFT TO SAID DRIVEN SHAFT INCLUDING LINKS POSITIONED RELATIVE TO SAID SHAFTS AND CONNECTED THERETO AT POINTS TO EFFECT A ROTARY DRIVE OF SAID DRIVEN SHAFT RESPONSIVE TO MANUAL DISPLACEMENT OF SAID DRIVING SHAFT

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