US 3196221 A
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Description (OCR text may contain errors)
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VIBRATION PROOF BEAM-DEFLECTIN Filed Feb. 1 1, 1963 INVENTOR. V. BRAUNAGEL MAGNU 7 TORNEY July 20, 1965 M. v. BRAUNAGEL 3,196,221
VIBRATION PROOF SWITCH WITH RESILIENT BEAM-DEFLECTING ACTUATOR STRUCTURE 2 Sheets-Sheet 2 Filed Feb. 11, 1963 MAGNUS V.
ATTORNEY United States Patent VIBRATXON IPRQGF SWHTCH WlTH RESILIENT lilEAIVhDEFLE CTIN'G AtJTUATOR STRUCTURE Magnus V. Braunagel, Littieton, (1010., assignor, by mesne assignments, to Space Technology and Research Corporation, Denver, Colo., a corporation of (Iolorarlo Filed Feb. 11, 1953, Ser. No. 269,22? 7 Qlaims. (Cl. filth-11) This invention relates to electrical switching devices and more particularly to an electrical switch having provisions to prevent a change of condition from on to off or vice versa under the influence of vibration.
Modern technology, particularly as related to space vehicles and their support and test equipment, has posed many new problems and has raised the standards of reliability to a considerable degree. Space vehicles of all kinds are extremely expensive and every effort is made to prevent their loss or failure of a mission because of the malfunction of a relatively simple and inexpensive component. When these vehicles are manned the stakes are infinitely higher. Among other things it is essential that electric circuits be maintained in predetermined open or closed condition during the requisite periods of time regardless of any unfavorable operating environment.
Gne of the principal problems in connection with electrical switches is vibration. The operation of a rocket motor during liftolf and climb frequently induces extreme vibration in various parts of its associated space vehicle or missile. This vibration is sometimes severe enough to cause the contact element of a switch to open or close a circuit contrary to its programmed operation and this is usually sufiicient to cause a malfunction which results in failure of the mission.
While a switch must remain in its intended position of adjustment regardless of undesired displacement forces it is also important that it should be adjustable by relatively small actuating forces because the available energy in a space vehicle must be carefully conserved. Some prior art switches have been operable with small forces but have been subject to unintended displacement by vibration. Others have been relatively vibration-proof at the expense of high actuating forces.
The novel construction and arrangement of the present switch overcomes these dih'iculties in a simple and effective manner. The basic elements of the switch include a support carrying a plurality of electrical conductors having contact surfaces which are preferably resilient, the conductors being held in fixed relation with respect to the support. A switching element is movably carried by the support and is provided with a contact member for conducting engagement with the contact surfaces in one selected position of the switching element. In another, neutral, selected position of the switching element, the contact member is out of engagement with the contact surfaces.
At least one resilient beam is afiixed at one end to the support and its free end engages an actuator to be moved thereby. The switching element is provided with abutment means which engage an intermediate part of the beam. When the beam moves in a given direction, its engagement with the abutment means causes the switching element to move in the same direction. The actuator, which is movably carried by the support, has a beam-deflecting surface provided with a discontinuity, usually in the form of an inwardly directed slot. When the beam and the actuator are in neutral position the free end of the beam is engaged in the slot and its resistance to deflection is sufiicient to retain the actuator in neutral against the effect of any vibratory force. When the actuator is deliberately moved manually or by a servomechanism its ice beam-deflecting surface bends the beam which rides out of the slot. The bending causes movement of the switching element to contact position and the free end of the beam resiliently presses against the beam-deflecting surface. This pressure and the frictional contact prevents the actuator from moving out of adjusted position, and the beam is prevented from returning to its neutral position by the interference of the beam-deflecting surface.
In its presently preferred form the support is a casing having a generally cylindrical interior and the switching element is a rotor mounted in the casing for rotation about the casing axis. Contact members are located in opposed re.ation at both faces of the rotor. The electrical conductors pass through the end walls of the casing and the resilient contact surfaces are in wiping relation with the rotor faces. Preferably there is one input terminal and one output terminal on each side, and the inputs are connected together and the outputs are connected together to form a redundant system. The resilient contact faces are a first assurance that contact will not be lost during any axial float of the rotor but, in any event there is the second assurance that as the rotor moves axially away from one pair of terminals it moves into closer engagement with the other pair.
The resilient beams are preferably duplicated on op posite sides of the rotor and have their outer ends fixedly mounted in cantilever fashion in the surrounding wall of the casing. The actuator is generally cylindrical and coaxial with the rotor, with its outer surface serving as the beam-deflecting surface. One or more discontinuities are provided in the form of slots having axial and radial extents and the free ends of the beams extend radially into the slots in neutral position. The rotor can be turned in either direction to deflect the beams and rotate the rotor correspondingly. Therefore a second set of terminals and contact members may be provided so that different circuits may be closed by rotor movement in opposite directions. Additional sets may be spaced around the periphery so that a large number of circuits may be controlled by a single switching mechanism.
The same basic principles may be incorporated in a push-pull switch, the actuator and the switching element being parallel rod-like members mounted for axial sliding movement.
The actuator is small and very light and even under conditions of very severe vibration does not develop enough force to displace the beams from their neutral position. However the mechanical advantage of the arrangement is very high and the deliberate application of relatively low force to the actuator will displace the beam. in the displaced position the principal force of the beam is substantially normal to the direction of movement of the beam-deflecting surface of the actuator. Hence, even when it is subjected to vibration it has no tendency to return the actuator to neutral position. In fact the pressural and frictional contact prevent any movement of the actuator. It can be seen then that the novel switch possesses unusual resistance to vibration while retaining relative ease of deliberate actuation.
Other advantages and features of novelty will become apparent as the description proceeds in conjunction with the accompanying drawings, in which:
FIG. 1 is an exploded view in perspective of a pre ferred form of the invention;
FIG. 2 is a sectional elevational view of a complete switch in accordance with the invention, particularly illustrating the mechanically cooperating parts;
FIG. 3 is a view similar to FIG. 2 particularly illustrat ing the electrically cooperating parts;
FIG. 4 is a schematic view in elevation showing the mechanical and electrical parts in neutral position;
FIG. 5 is a view similar to FIG. 4 showing the parts in one adjusted position in which certain circuits are closed; and
FIG. 6 is a view similar to FIG. 4 showing the parts in another adjusted position in which different circuits are closed.
The principal coacting elements of the presently preferred form of the invention are illustrated in FIG. 1, in which a support for the other elements is shown as a casing made up of two substantially identical casing halves or housings 1t) and 12. Although the housings may have other shapes they are preferably generally cylindrical, at least internally, and each has an end wall 14 and 16 respectively and surrounding walls 18 and 2t? respectivelyv Pins, not shown, pass through bores 22 and are engaged at each end by screws 24 to align the housings and hold them in assembled relation.
Electrical conductors or terminals 26 and 28 pass in an axial direction through the end walls near the periphery and are provided at their inner ends with resilient contact surfaces 36 for engagement with a contact element. Pairs of terminals are disposed in peripherally spaced relation as shown for purposes to be described later Each casing half or housing is provided with a counterbore 32 and annular shoulder 34 and, in assembled relation as seen in FIGS. 2 and 3, they cooperate to form a bearing channel 36.
A switching elementis provided in the form of a disklike rotor 38 having end faces 49 and t2 and an annular peripheral wall 44. By reference to FIGS. 2 and 3 it will be seen that the edge of the rotor fits in bear-ing channel 36 for rotation about the axis of the casing interior. Contact members 45 are provided at each face of the rotorand, as seen in FIGS. 1 and 3, actually consist of a solid bar passing through the thickness of the rotor. In some cases it is desirable to double the number of circuits which can be handled and this is accomplished by merely inserting discrete contact members in each face. Each contact member has a sufiicient radial extent to conductively engage a pair of terminals 26 and 28 and the contact members are peripherally spaced at proper intervals to engage the terminals in a manner to be described later.
The means for moving or adjusting the rotor to selected positions of contact or non-contact and for holding it in such positions includes a plurality of resilient beams 46 each fixedly mounted at its outer end in cantilever fashion in housing walls 18 and 20 by a plug 48. A plurality of pins 50 pass in an axial direction through bores 52 in the rotor and their ends are bifurcated to slidingly receive the intermediate portions of the beams. The latter in neutral position extend radially inward toward the axis of rotation and pass through the slots in the abutment means or pins 59, as best seen in FIG. 2, thus holding the rotor in its neutral position with the contact members out of engagement with all of the terminals.
Control of the positions of the beams and rotor is accomplished by actuator 54 which'inclu-des a generally cylindrical central body portion 56 having end walls 58 and 60 engaging end walls 14 and 16 of the casing and a mounting and control shaft 62 which'extends through bearing apertures 64 and 66 in the casing end walls 14 and 16. The shaft carries the actuator for rotation about the axis of rotor 38, and a handle or any other means such as a servomechanism may be attached to either end of the shaft to rotate the actuator to selected adjusted positions. The beam-deflecting, enerally cylindrical, surface of the actuator is punctuated by a plurality of discontinuities in the form of slots 68 which extend in an axial direction from end to end of the actuator body as shown. The slots are enlarged inwardly toward the axis and may be formed by drilling or machining in any suitable fashion, The central body of the actuator can alternatively be formed as a central disk surrounded by .a thin walled sleeve and the ends of the sleeve can be slotted, permitting access to the large open space within. In assembled relation the actuator is freely received in an axial bore 7% formed in the rotor.
Again referring to FIG..2, it will be seen that the resilient beam means extend radially inwardly at each side of the rotor and through the slotted ends of pins 50, the inner ends of the beams passing into the discontinuities or slots in actuator body 56. In this neutral position the beams resist any unintended rotation of the actuator resulting from vibration, shock or other causes, and hence they prevent movement of the rotor to any position in which its contact members will engage the contact surfaces of the conductor terminals.
' Turning now to FIG. 4, 5 and 6, the relative arrangement and action of the cooperating elements are illustrated. FIG. 4 shows the elements in neutral position. There are three sets of beams 46, pins 5i? and slots 63 in the actuator body 56. The number may be increased or decreased but in any event the peripheral spacing should be even. There are six sets of terminals 26, 28 and contact members 45. Pairs of sets are evenly spaced around the periphery and a pair of terminal sets is located peripherally between a pair of contact members. In this neutral position all circuits are open and the terminals are a short distance from their respective contact members.
sixty degrees in a counter-clockwise direction asindicated by arrow 72. An edge of each slot 68 has deflected its respective beam in a corresponding direction until the beam has ridden entirely out of the slot and its free end is resting on the beam-deflecting surface of the actuator. The intermediate portion of each beam has moved a lesser distance but in the same sense, and has therefore moved its pin 59 and the rotor 38 in a counter-clockwise direction. The extent of this movement is just suflicient to bring one of each pair of contact members 45 into conductive engagement with its respective pair of terminals'26, 28,- and the other one of each pair moves away from its neighbors. Thus, three circuits are closed by this single movement.
It is to be noted that deliberate movement of the actuator and beams away from neutral can be accomplished with a relatively low force because of the mechanical advantage of the arrangement, but undesired forces such as )vibration have little efi ect because they would have to be rotary in character to cause any part to move and the momentum of the light weight actuator is almost negligible. In the adjusted position of FIG. 5, the returning force of the beam is largely normal to the deflecting surface and has no rotational effect on the actuator, On the contrary, this force, acting through the frictional interengagement serves as an effective brake against even rotational vibration. Accordingly the switchis practically locked against extraneous forces in any adjusted position.
Return of the switch to neutral is accomplished by reverse rotation of the actuator, the free ends of the beams dropping into the slots 68. As soon as they begin to enter the slots they resiliently snap the actuator and rotor back to neutral, breaking the circuits quickly tosubstantially eliminate arcing. Actuation of the switch to close the other group of circuits is accomplishedby rotating the actuator in a clockwise direction, indicated by arrow '74, as illustrated in FIG. 6. The operation is the exact reverse of FIG. 5, and the description will not be repeated,
The circuitry illustrated in FIG. 3 includes a single electrical lead 76 connected to both terminals 26 at opposite sides of the rotor and a single electrical lead 78 connected to both terminals 28. Thus, if either set fails the other will maintain the circuit, providing maximum reliability. The redundant mechanical elementslikewise provide maximum reliability.
While the novel switch finds its greatest utility in space In FIG. 5 the actuator has been turned approximately vehicles, its reliability makes it highly desirable also for ground installations such as the support equipment for space vehicles which must also function properly at all times. It finds equal application in vibration equipment of all kinds where ordinary switches are prone to failure. The switch is completely enclosed except for the operating shaft which can be sealed readily to make it waterproof, and is thoroughly protected from damage of any kind.
It will be apparent that various changes and modifications may be made in the construction and arrangement of parts without departing from the spirit of the invention and it is intended that all such changes and modifications shall be embraced within the scope of the following claims.
1. A vibration-proof switch comprising: a hollow casing having front and rear end walls with a surrounding wall between them, the interior of said casing being generally cylindrical in form with its axis substantially normal to the front and rear end walls; at least one pair of electrical conductors extending through an end wall and provided with resilient contact surfaces adapted to be engaged by a contact member to complete a circuit through said conductors; a disk-like rotor mounted in said casing for rotation about the central axis of said casing; a contact member mounted at least at one face of said rotor near its periphery for conducting engagement with said contact surfaces in one selected position of said rotor and for disengagement from said contact surfaces in another selected position of said rotor; and means to move said rotor to said selected positions including a pair of resilient beams located adjacent opposite faces of said rotor and having their outer ends fixed in the surrounding wall of said casing, their inner ends extending radially inwardly toward the axis of rotation; a pin mounted in said rotor parallel to the axis of rotation and having its ends projecting from the faces of said rotor into force transmitting engagement with said beams to transmit forces from said beams to said rotor for rotation thereof to said selected positions; an actuator mounted in said casing for rotation about an axis concentric with the axis of said rotor; the outer surface of said actuator being generally cylindrical and constituting a beam-deflecting surface with a discontinuity therein to provide a radial depression to receive the radially inwardly extending ends of said beams in neutral position; rotation of said actuator from its neutral position causing said beam-deflecting surface to deflect said beams away from their radial attitudes and apply rotational force to said pin to rotate said rotor to a selected position in which said contact member conductingly engages said contact surfaces; return of said actuator to a neutral position permitting the beams to reenter the radial depression and return the rotor to noncontact position; the resistance of said beams to deflection from their neutral position serving to hold the rotor in neutral, non-contact position, and pressural engagement of the inner ends of the deflected beams with the beamdeflecting surface of the actuator serving to hold the rotor in contact position.
2. A switch as claimed in claim 1, in Which there are a plurality of sets of spaced conductors and contact surfaces, a plurality of contact members, a plurality of pairs of beams, and a plurality of discontinuities in the beamdeflecting surface evenly spaced around the periphery to produce balanced mechanical forces and to provide an increased number of independent circuits.
3. A switch as claimed in claim 1; and, in addition thereto, at least a second pair of electrical conductors extending through the opposite end wall toward and in substantial alignment with the first pair and provided with resilient contact surfaces; said contact member being duplicated on both faces of said rotor and said resilient contact faces being adapted to pressurally engage both faces of said rotor and said duplicated contact member to ensure constant contact in the event of axial float or vibration of said rotor.
4. A switch as claimed in claim 3, in which a single electrical load is connected to a first conductor in each of said pairs and a single electrical lead is connected to a second conductor in each of said pairs; whereby the duplicated contact member at each face of the rotor completes the same circuit to provide a fail safe redundant electrical system.
5. A vibration-proof switch comprising: a hollow cas ing; at least one pair of electrical conductors extending through a wall of said casing and provided with contact surfaces adapted to be engaged by a contact member to complete a circuit through said conductors; a rotor mounted in said casing for rotation about a central axis; a contact member mounted on said rotor adjacent its periphery for conducting engagement with said contact surfaces in one selected position of said rotor and for disengagement from said contact surfaces in another selected position of said rotor; and means to move said rotor to said selected positions including a pair of resilient beams located adjacent opposite faces of said rotor and having their outer ends fixed in an outer wall of said casing, their inner ends extending radially inwardly toward the axis of rotation; abutment means extending from opposed faces of said rotor and engaging said beams, said beams upon deflection functioning to move said abutment means and in turn move said rotor to one of said selected positions; a generally cylindrical actuator mounted in said casing for rotation coaxially of said rotor to selected positions; its cylindrical surface constituting a beam-deflecting surface provided with a discontinuity enlarging inwardly and adapted to receive the radially inwardly extending ends of said beams in neutral position; rotation of said actuator from its neutral position causing said beam-deflecting surface to deflect said beams away from their radial attitudes; engagement of said beams with said abutment means serving to displace them and rotate said rotor to a selected position in which said contact member conductingly engages said contact surfaces; the resistance of said beams to deflection from their neutral position serving to hold the switching element in non-contact position, and pressural engagement of the inner ends of the deflected beams with the beamdefiecting surface of the actuator serving to hold the switching element in contact position.
6. A switch as claimed in claim 5; and, in addition thereto, at least a second pair of electrical conductors extending through said wall and having contact surfaces peripherally spaced from said first pair a predetermined distance; and a second contact member mounted on said rotor and peripherally spaced from said first contact member a predetermined distance; said contact members and contact faces being so arranged with respect to each other that they are all out of contact in neutral position; the first contact member engages the first pair of contact surfaces when the actuator is rotated from neutral in a first direction; and the second contact member engages the second pair of contact surfaces when the actuator is rotated from neutral in the second direction.
7. A switch as claimed in claim 5 in which said rotor is provided with a large central opening and said actuator passes through said opening and is surrounded by said rotor.
References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner.