US2463659A - Centrifugally nonresponsive electrical snap switch - Google Patents

Description

March 8, 1949. R. K. TIEDEMAN CENTRIFUGALLY NONRESPCNSIVE ELECTRICAL SNAP SWITCH '3 Sheets-Sheet 1 Filed Oct. 1, 1945 (Ittorneg March 8, 1949. I R. K. TIEDEMAN 2,463,659

CENTRIFUGALLY NONRESPONSIVE ELECTRICAL SNAP SWITCH Filed Oct. 1 1945 3 Sheets-Sheet 2 Snuenlov .ZFMe/TK fizzle/71412 Cxttomeg March 8, 1949. R K, TlEDEMAN 2,463,559

CENTRIFUGALLY NONRESPONSIVE ELECTRICAL SNAP SWITCH Filed Oct. .1, 1945 s Shets-Sheet 5 3 nventor Cittorneg Patented Mar. 8, 1949 CENTRIFUGALLY NONRESPONSIVE ELECTRICAL SNAP SWITCH Robert K. Tiedeman, Upper Montclair, N. J assignor to Curtiss-Wright Corporation, a corporation of Delaware Application October 1, 1945, Serial No. 619,530

9 Claims. 1

This invention relates to an electrical switch mechanism and more particularly to an improved switch mechanism which has particular application, for example, in an aircraft propeller assembly of the electrically operable controllable pitch change type.

The invention has particular reference to an improved switch mechanism of the dual contact type wherein a resilient link toggle arrangement is adapted to be operated to maintain an electrical circuit either open or closed.

In a known electric controllable pitch propeller assembly for aircraft, a plurality of switch mechanisms are associated with the hub end of the speed reducer housing for operation in suitable manner to open the circuit of the pitch change electric motor when the propeller blades reach limiting low, high, feather or reverse pitch angles.

The principal object of the invention is to provide improved switch mechanisms operable for the purpose stated which have high current carrying capacity, which provide a large breaker gap between the fixed and movable contacts, which afford rapid operation of the movable contacts toward and away from the fixed contacts, and which are not adversely affected by the presence of lubricants.

A further object of the invention is to provide an improved switch mechanism which, at its cooperative contacts, is not adversely affected by centrifugal force resulting from high propeller H. P. M.

With these and other objects in view, the invention resides in the novel construction, combination, and arrangement of parts, the novel features of which are set forth with particularity in the appended claims, the invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, being best understood from the following description of a specific embodiment, when taken in connection with the accompanying drawings, in which:

Figure 1 is a fragmentary, side elevational view, partly in section, illustrating a switch mechanism, constructed in accordance with the invention, associated with the speed reduced mechanism of an electric, controllable pitch change aircraft propeller assembly;

Fig. 2 is an elevational view illustrating the inner end of the switch mechanism;

Fig. 3 is a vertical sectional view of the switch mechanism taken on the line 33 of Fig. 2 with the switch contacts in closed position;

Fig. 3a is a fragmentary view illustrating cooperating parts of my switch mechanism as the same is shown in Fig. 3;

Fig. 4 is a view corresponding with Fig. 3 and illustrates the initial contact of a switch-operating member with a switch mechanism constructed in accordance with the invention;

Fig. 4a, is a fragmentary view illustrating cooperating parts of my switch mechanism as the same is shown in Fig. 4;

Fig. 5 is a view corresponding with Figs. 3 and 4, the switch mechanism being shown as in open position;

Fig. 5a is a fragmentary view illustrating cooperating parts of my switch mechanism as the same is shown in Fig. 5;

Fig. 6 is a vertical sectional view taken on the line 6-5 of Fig. 2 and illustrating the manner in which the movable contacts are' pivoted to the breaker arm;

Fig. '7 is a transverse sectional view taken on the line 'll of Fig. 6 looking in the direction of the arrows;

Fig. 8 is a transverse sectional view taken on the line 88 of Fig. 6;

Fig. 9 is a perspective view of the movable contact actuating spring assembly per se; and

Fig. 10 is a fragmentary plan view illustrating a modified arrangement for seating one end of each of the switch loading springs.

Referring to the drawings and particularly to Fig. 1, a fragmentary portion of an annular housing III for a gear reduction drive system of a controllable pitch-change mechanism for aircraft propellers is shown with an electrical switch H constructed in accordance with the invention in cooperable relation therewith. As shown, the switch I l occupies a chamber l2 defined or formed by a housing extension l3 of said housing Ill. The switch [I is suitably secured to the housing If! by a plurality of bolts it whereby it is operatively related to a cam base, disk or drum l5 which carries a cam segment I5a, the drum [5 being rotatably movable on its axis in response to movement of a low speed bell gear iii in known manner.

In pitch-change mechanism as aforesaid, it is desirable that three switches of the character herein described and illustrated be employed to control the current supplied to a motor utilizable for driving said pitch-change mechanism. Cne of these switches automatically opens the circuit of said motor when the propeller blades reach a selected low-pitched position. Another of the switches automatically opens the circuit of said motor when the propeller blades reach a selected high-pitch position and the third of said switches automatically opens the motor circuit when the propeller blades reach feather position. Moreover, in special applications, a fourth switch of the character described may be utilized to open the motor circuit when the propeller blades are moved to selected reverse pitch position. Each of the switches is actuated by a cam segment IEa of the character described above, it being understood that the drum I5 carries a plurality of cam segments l5a which are suitably spaced around the periphery thereof, one of these cam segments i5a being provided for each of the switches l l The switch I! includes a block I! of insulation material which is transversely recessed on its underside, as at 18, to provide clearance for a pair of fixed contacts is and 25) which are secured end- Wise in one portion of said block in side-by-side relation. Coactable with the fixed contacts 19 and 2B are the respective movable contacts 2i which are operated in the manner hereinafter described.

Referring particularly to Fig. 8, a terminal member 22 is shown as disposed within said recess Li and secured to the fixed contact ill, the terminal member 22 being connected to a screw threaded eyelet 23 lying substantially flush with the outer face of the block l7. Another terminal member 24 also disposed within the recess H3, in

spaced relation to the terminal 22, is secured to the fixed contact and, similarly, is connected to a screw threaded eyelet 25 at its free end which is suitably supported at one side of the block ii.

A triangular metallic plate 26 having a pair of spaced protuberances '21 formed thereon is suitably secured, as by a rivet 26a to the underside of that end portion of the insulating block i! which is opposite the end portion to which the fixed contacts if} and Eli are secured, said protuberances 2'! being provided for a purpose hereinafter described.

The block of insulation material l! is secured between the bifurcated end portions, respectively, of suitable supporting means which, as shown, comprises a pair of duplicate plate members 28 and 29. A plate 23a of insulation material is in contact with the outer face of the plate 28 and, preferably, thin sheets 28?; of insulation material having greater area than the block ill are sandwiched between said block H and the respective plate members, Figs. 7 and 8. In order to secure these parts in assembled relation, I utilize a plurality of rivet pins 30, the outermost two of which, Figs. 3, 4, and 5, pass through the plate 28a, the respective bifurcations of the plate member 28, the adjacent insulating sheet 281), the block if the other insulating sheet 281) and the respective bifurcations of the plate member 29. Below one end portion of the block H, a rivet pin 3!] extends through the plate 28a, the plate member 28, the two insulating sheets 28b, and the plate member 29. In alinement with the rivet pin 38 last named, a rivet pin 38a secures together, on the one hand, the plate 28a, the plate 28 and the adjacent insulating sheet 28b, Fig. 3, and, another rivet pin 36b secures together, on the other hand, the plate member 29 and the adjacent insulating sheet 28b, Fig. l.

The aforesaid plate 28a serves as an insulating support for the eyelet 25 of the terminal member 24, Fig, 8. The opposite end portion of each of the plate members 28 and 29 terminates in an arcuate, base-forming portion each of which has a plate 32 suitably secured thereto, Figs. 3-6 inelusive. Each plate end portion and associated plate is apertured as indicated so that the switch ll may be secured to the housing ID by the bolts M as described above. One of the plates 32 comprises an inwardly projecting lip 32a utilizable as hereinafter described.

Referring particularly to Figs. 3-6 inclusive,

' the plate members 28 and 29, substantially in the central transverse plane of the switch, are shown as supporting a transversel disposed member or pin 33 which supports a sleeve 33a secured at its opposite respective ends to spaced ears 34a, 34a, (Figs. 2 and '7) integrally formed with a rocker plate 34 which comprises an aperture 34b disposed between said ears. The rocker plate 34, at one end thereof, comprises a lip 34c utilizable as hereinafter described. The rocker plate 34, at the other end thereof, comprises a cam-shaped actuating member 3403 projecting from the lower surface thereof.

Disposed on the top surface of the rocker plate 34 above the actuating member 36d is a plate having, adjacent one end thereof, a pair of spaced pins 36, Fig. '7. The lower ends of the pins 36, for positioning purposes, are received, respectively, in slots formed in the rocker plate 3 5, Fig. 2. Disposed on the upper surface of the plate 35 is an angle plate 3'1, a rivet 38 securing the plates 3'! and 35 to the rocker plate 34, Fig. 4. Th angle plate 3'! is formed from resilient material and extends part way around a sleeve 39 carried by the aforesaid sleeve 33a and terminates in an angular section 37a having projecting therefrom a central tongue 312), Fig. 8, utilizable as hereinafter described. The angle plate 31 further cornprises knife edges 31c disposed at opposite respective sides of the tongue 31b.

Another plate 49 has a pair of spaced ears 413a, 411a at one end thereof, Fig. 7. The ears Mia are disposed inwardly of the respective ears 34a and said ears 40a are loosel mounted on the sleeve 33a at opposite respective ends of the sleeve 39. The other end of the plate 40 comprises a pair of spaced ears 40b extending therefrom in rightangular relation, Figs. 1, 3, 4, 5 and 6. A pin 4 I, carried by the ears 40b, loosely supports a strip 42 of insulation material to which is suitably secured a metallic strip 43 carrying, in suitable spaced relation, the above described movable switch contacts 2!. The plate 40 is apertured as indicated at 40c and said plate 40, in the plane thereof, has a central tongue 40d extending in this aperture. At opposite respective sides of the tongue 40d, the plate 40 comprises knife edges 406.

In accordance with the invention, a plate 45, preferably metallic, is shown as supported by the angle plate 3'1, the central tongue 31b of the latter extending loosely through a central slot 45a formed in said plate 45. A second plate 16, preferably metallic, has a central slot 46a through which loosely extends the aforesaid central tongue Mid of the plate 40, the plate 46 having a central tongue 46b, Fig. 9. The plates 45 and 36 support a coil spring arrangement ll? in the manner hereinafter described and the aforesaid tongue 46b positions and locates said spring arrangement M with respect to said plates 45 and it.

Referring particularly to Fig. 9, the coil spring arrangement 41 is shown as comprising two coils il'a, l'ia which have a common axis. The inner ends of these coils are connected together by an integral U-section 4117 and the central portion of this section is clamped by a folded portion Me of the plate 48. In generally similar manner, the outer ends of the coils 41a, 41a are connected together by an integral U-section 410, the central and two side portions thereof being clamped, re-- spectively, by folded portions 45b of the plate 45.

Referring particularly to Fig. 7, the pins 36 are shown as received in the respective ends of a pair of coil springs d9, 39 which, at their other ends, receive the hereinbefore described protuberances 21. As 'will be'obvious, the springs d9 bias the pivoted system comprising the rocker plate 34, the plate 35 and the angle plate 3? in a counterclockwise direction, Figs. 3 and 5.

In lieu of the plate 25 and its protuberances Zl, there may be utilized the modified arrangement shown in Fig. 10 for supporting the springs 49 at adjacent ends thereof. Thus, as shown in Fig. 10, the plate 25 is omitted and an angular member 50 is provided, the latter having spaced protuberances 5| which are received in adjacent ends of the springs 49. The member 58 may be fixed in position by riveting one end thereof to the plate member 2 S at 52 and securing the other end thereof by one of the hereinbefore described rivets 30.

Referring particularly to Figs. 3 and 3a, the switch mechanism is shown in its closed position. At this time, the springs 49 are holding the rocker plate 34 in such position that the lip 34c thereof is in engagement with one of the rivet pins 3t. Furthermore, at this time, some energy is stored in the coils 610., Ma of the spring arrangement 41. As a result, the plate 55 is held in engagement with the set of knife edges 31c and the plate i6 is held in engagement with the set of knife edges 40c. As stated, the tongue 31b of the angle plate 31 is loosely received in the slot 45a of the plate 45. Similarly, the tongue 48d of the plate M) is loosely received in the slot Mia of the plate 6. These tongues restrain the respective plates d5, 46 for pivotal movement with respect to the angle plate 31 and the plate ii] during the opera... tions hereinafter described.

A component of the force applied by the spring arrangement M to the set of knife edges Mle is effective on the movable switch contacts 2! to hold them positively in engagement with the respective fixed contacts i9, 26. As a result, the circuit of the switch mechanism is closed between the eyelets 23 and 25, Fig. 8. Any circuit which is connected thereto, for example, the circuit of the aforesaid pitch-changing motor is likewise closed, this circuit including the conductors 53 and 55, -8, which are connected, respectively, to the eyelets 23, 25.

Responsive to movement of the drum E5 in a counterclockwise direction from the position thereof shown in Fig. 3 to that shown in Fig. 4, the cam segment i'5a engages the member 3M of the rocker plate 34 and moves the latter, while compressing the springs 49, clockwise to the position shown in Figs. 4 and 4a. The angle plate 31 is secured to the rocker plate 3 for movement therewith as a unit and, accordingly, responsive to the last named movement of said rocker plate 34, the angle plate 31', accompanied by some flexing thereof, moves clockwise from the position shown in Figs. 3 and 3a to the position illustrated in Figs. 4 and 4a. The hereinbefore described plate 45 is connected to the angle plate 37 by the tongue 31!) and, due to this connection, the described movement of the angle plate 3! causes the plates 45 and 46 together with the therebycarried spring arrangement 4! to move in a counter-clockwise direction substantially about axes defined by the respective sets of knife edges 310 of the angle plate 31 and ine of the plate M, the

coil springs 41a. being wound to some extent and energy stored therein during the aforesaid movement of the angle plate 37.

As the parts are shown as positioned in Fig. la, the center of the hereinbefore described pin 33, the knife edges 310 of the angle plate 31 and the knife edges We of the plate as are shown as disposed substantially in the same plane P. This is substantially one critical position of the sets of knife edges 31c and We. Durin the described movement of the parts as referred to above, the described switch contacts remain closed under the influence of the spring arrangement 41.

In response to further slight movement of the drum H5 in a counter-clockwise direction beyond the position thereof shown in Fig. 4, the set of knife edges 310 of the angle plate 31 are moved slightly in a clockwise direction from the position thereof shown in Fig. do. As a result, some of the energy previously stored in the end portion of the resilient angle plate ill becomes effective against the opposing force of the spring arrangement 4'! to move the set of knife edges 37c beyond the aforesaid critical position and, as soon as this happens, the coils lla of the spring arrangement 4'! become free to unwind to some extent and to release a part of the energy previously stored therein. As a result, the plates 45 and it together with the thereby-carried spring arrangement 41 continue the previously described movement thereof in a counter-clockwise direction substantially about axes defined by the respective sets of knife edges, this continuing movement, however, occurring in a snapping fashion. Resulting from this operation, the plate 40 is swung snap-like in a counter-clockwise direction to the position shown in Figs. 5 and 5a to thereby move the switch contacts 2! snapfashion from the respective fixed contacts i9, 20 with resultant opening of the motor circuit. When the switch is open as shown in Fig. 5, the plate 40, under the influence of the spring arrangement 41, is held in engagement with a surface of the block ll, this surface acting as a stop to limit counter-clockwise movement of the plate 40.

In view of the foregoing, then, the switch is shown in open position in Figs. 5 and 5a. When the drum i5 moves to sufiicient extent in a clock- Wise direction from the position thereof shown in Fig. 5, the springs 49 swing the angle plate 3'1, accompanied by some flexing thereof, in a counter-clockwise direction until, eventually, the sets of knife edges 31c and tile are in alinement with the center of the pin 33. This is substantially the other critical position of the sets of knife edges. The last described movement of the angle plate 31 causes the plates 45 and 46 together with the thereby-carried spring arrangement i? to move clockwise from the position shown in Fig. 5 substantially about axis defined by the respective sets of knife edges. During this operation, the coil springs 41a are wound to some extent with resultant storage of energ therein. During the movement last described, the switch contacts remain open under the influence of spring arrangement 41.

In response to slight additional movement of the drum l5 in a clockwise direction, some of the energy previously stored in the end portion of the resilient angle plate 31 becomes effective against the opposing force of the spring arrangement l! to move the set of knife edges 37c beyond the second critical position, and as soon as this happens, the coils 41a of the spring arrangement 4'! become free to unwind to some extent and to release a part of the energy previously stored therein. As a result, the plates 45 and 46 together with the thereby-carried spring arrangement =3! continue the previously described movement thereof in a clockwise direction substantially about axes defined by the respective sets of knife edges, this continued movement, however, occurring in a snapping fashion. Resulting from this operation, the plate 40 is swung snap-like in a clockwise direction to the position shown in Figs. 3, 3a, 4 and 4a to thereby move the switch contacts 2| snap-fashion into engagement with the respective fixed contacts I9, 20 with resultant closing of the motor circuit. It will be understood that, after the cam segment iila is disengaged from the member 3411 of the rocker plate 34, the springs 49 return the angle plate 3'! and parts secured thereto to the respective positions shown in Figs. 3 and 6 wherein the angle plate lip 340 is in engagement with the rivet pin 3! Fig. 3.

Referring to Fig. 1, it will be noted that a switch of my invention is shown as mounted in a housing extension I3 of the housing [0, the latter enclosing the gear reduction drive mechanism of the pitch-changing mechanism for an aircraft propeller. The switch H is so mounted in the housing l3 that the engaging surfaces between the fixed contacts 18 and 20 and the respective movable contacts 2|, when the switch is closed substantially coincides with a plane extending radially and longitudinally of the housing it. During operation of the aircraft propeller, the housing l rotates at high speed and, with the arrangement described, the effect of centrifugal force is such that little or no pressure is applied to the cooperating switch contacts tending to open or close them. Likewise, when the movable switch contacts are open, the effect of centrifugal force is substantially nil as regards any tendency to close them. These are desirable features of the invention.

The hereinbefore described spring arrangement 4'! including the coils 47a, 41a thereof serve in an. advantageous manner to cause the movable switch contacts 2! to engage the respective fixed contacts l9 and 26 under pressure which is adequate for the purpose intended, namely, the maintenance of close mechanical engagement between the respective sets of 00- operating contacts.

Another feature of the invention resides in the fact that the switch is of such character that the moving parts thereof have minimum mass. Even so, due to the utilization of the described springs, little or no vibration results during operation of the rotatable system.

Prior to the time that the switch mechanism of my invention is disposed in the housing extension [3, undesired pivotal movement of the rocker plate 34 in a direction away from the rivet pin 30 might occur under some circumstances. It is for this reason that the lip 32a is provided on one of the plates 32, said lip 32a being engageable by the lip 340 of the rocker plate 34 under the conditions recited.

Although the switch mechanism of my invention has been illustrated and described in connection with a particular application thereof, it shall be understood that the invention is not to be thus limited. This is true because it will be obvious to those skilled in the art that my novel switch mechanism has many applications other than the aircraft propeller art.

While the invention has been described with respect to a certain particular preferred example which gives satisfactory results, it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent, is:

1. In a snap switch mechanism of the character described, fixed and movable contact means, a supported member, a plate supporting said movable contact means and being carried by said supported member in freely oscillatory relation, means comprising a spring arrangement consisting of two coil springs connected together at their inner and outer ends respective ends being extended from the coils and one said end engaging said supporting plate, and a member comprising a resilient end portion coactable with and movable past said supporting plate and engaged with the other end of said spring arrangement to operate the same and impart snap-like movement to said supporting plate whereby said movable contact means is moved with respect to said fixed contact means.

2. In a rotating body, a snap action switch subject to centrifugal force including a support pin on the body, a substantially centrifugally balanced switch actuating member freely swingable on said pin, means for swinging said member about said pin, a resilient projection on said member having an outwardly facing abutment extending substantially radially outward from said pin and body in the direction of action, of the centrifugal force, a contact carrying arm swingable on said pin and extending substantially radially outward therefrom and in the direction of action of said centrifugal force, means including a fixed contact cooperable with the arm contact to establish swing limits for said contact carrying arm, said arm having an inwardly facing abutment facing said actuating member abutment, and spring means between said abutments urging them apart, said arm being swingable for switch actuation substantially independently of the effects of centrifugal force, through a limited arc of swing on both sides of the direction of act-ion on said centrifugal force.

3. In a rotating body, a snap action switch subject to centrifugal force including a support pin on the body, a substantially centrifugally balanced switch actuating member freely swingable on said pin, means for swinging said member about said pin, a resilient projection. on said member having an outwardly facing abutment extending substantially radially outward from said pin and body in the direction of action of the centrifugal force, a contact carrying arm swingable on. said pin and extending substantially radially outward therefrom and in the direction of action of said centrifugal force, means including a fixed contact cooperable with the arm contact to establish swing limits for said contact carrying arm, said arm having an inwardly facing abutment facing said actuating member abutment, and spring means between said abutments urging them apart, said arm being swingable for switch actuation substantially independently of the effects of centrifugal force, through a limited arc of swing on both sides of the direction of action on said centrifugal force, said spring means comprising a coiled spring whose coil is displaced from said abutments having end portions extending from the coil and engaging said abutments.

4. In a rotating body, a snap action means subject to centrifugal force comprising an actuating member pivoted to the body for limited swinging, means for swinging said member, a projection on. said member having an outwardly facing abutment swingable with the member through substantially equal angles on either side of the line of action of said centrifugal force and passing through the member pivot, a switching arm swingably mounted on the body at a pivot lying on a body radius passing through said member pivot, an abutment on said arm swingable therewith and facing said member abutment, and resilient means bearing on said abutments and urging them apart, said member projection being elastic to broaden the angle of swing through which said member must pass to carry its abutment over the spring centers defined by said abutments.

5. A snap action means comprising an actuattially equal angles on either side of a central l line passing through the member pivot, an arm swingably mounted on the body at a pivot lying substantially on said central line, said arm having an abutment facing said member abutment, and resilient means bearing on said abutments and urging them apart, said elastic member serving to broaden the angle of swing through which said member must pass to carry its abutment over the spring centers defined by said abutments.

6. A snap action means comprising an actuating member pivoted to a body for limited swinging, means for swinging said member, a second member pivoted to said body for limited swinging, said members being swingable to either side of a central line passing through said pivots, and

7. A snap action means comprising an actuating member pivoted to a body for limited swinging, means for swinging said member, a second member pivoted to said body for limited swinging, said members being swingable to either side of a central line passing through said pivots and having facing abutments spaced from their pivots, one of said members having an elastic portion between its abutment and its pivot deflectable in the plane of swinging of the member, and resilient means between and bearing on said abutments urging them apart.

8. A snap action means comprising an actuating member pivoted to a :body for limited swinging, means for swinging said member, said member having an abutment spaced from its pivot, an elastic portion between said abutment and said swinging means to afiord angular displacement therebetween upon force application to said swinging means, a second pivoted member having an abutment spaced from its pivot, said two members being swingable to either side of a central line passing through said pivots, and resilient means between and bearing on said abutment to urge them apart.

9. A snap action means comprising an actuating member pivoted to a. body for limited swinging, means for swinging said member, said member having an abutment spaced from its pivot,

said swingin means to afford angular displacement therebetween upon force application to said swinging means, a second pivoted member having an abutment spaced from its pivot, said two members being swingable to either side of a cen- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 991,431 Duntley May 2, 1911 1,231,527 Long June 26, 1917 1,667,158 Ives Apr. 24, 1928 2,068,682 Keefe Jan. 26, 193'? 2,199,974 Whitney May 7, 1940 2,230,720 Jarvis a Feb. 4, 1941 2,328,266 Durbin Aug. 31, 1943 2,390,365 Gofl" Dec. 4, 1945

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