US2314291A - Control device - Google Patents

Description

March 16, 1943.

L. A. TAYLOR CONTROL DEVICE Original Filed June 19, 1940 INSULATION Inventor: Laurens A. Taylor; b N 6. 9M 9 His Attorney- Patented Mal-.716, 1943 CONTROL DEVICE Laurens A. Taylor, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Original application June 19, 1940 Serial No. 341,313. Divided and this application June 2. 1941, Serial No. 396,323

4 Claims.

My invention relates to a control device, and although not limited thereto, it has features which have particular application to electric switches.

This application is a division of my copending application Serial No. 341,313, filed June 19, 1940, which became Patent No. 2,300,993 on Nov. 3. 1942.

An object of my invention is to provide an improved electric control device which shall have a compact design, be capable of handling relatively high currents, and operate with a relatively small movement of its movable parts.

A further object of my invention is to provide a control device with a contact structure and a holding coil which will operate in an improved the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a side elevation of a control device which is provided with an embodiment of my invention; Fig. 2 is an end view of the terminal end of the device illustrated in Fig.' 1; Fig. 3 is a sectional side elevation of the device illustrated in Fig. 1 along line 3-3 of Fig. 2;

Fig. 4 is an end elevation along the lines 44 of Fig. 3; Fig. 5 is an end elevation along the line 5--5 of Fig. 3; Fig. 6 is an exploded perspective view of the bridging contacts of the device illustrated in Figs. 1 to 5; Fig. 7 is a sectional side elevation of one of the bridging contacts illustrated in Fig. 6, showing the mounting arrangement therefor; Fig. 8 illustrates a modified form of mounting arrangement illustrated in Figs. 3 and 6, and Fig. 9 diagrammatically illustrates a circuit which may be controlled by my improved control device.

Referring to the drawing, in Fig. 1' I have illustrated my improved control device having casings l0 and ii. The casing I'll may be made of any suitable non-conducting material, such as a molded product so that a plurality of terminals l2,,may be secured therein, as will be seen in the sectional view of Fig. 3. The casing ii may be made of any suitable material, such as a cast metal and it provides an enclosure for the switch and its holding coil l3, as well as a mounting arrangement for the control device.

Each of the terminals l2 may be provided with a contact H which projects into a hollow portion 15 of the casing ID. The contacts I have parallel contact faces l6 and are positioned a suitable. distance from each other and around the periphery of a circle whose center may be the longitudinal axis of a shaft H, as will be seen in Fig. 5. The shaft I1 is supported at one end in a hole ill of the molded casing l0 and at the other end by a bearing l9 which is held in a hole in a cover part 20 of the casing i I. The bearin i9 is tightly secured in place by a nut 2| which cooperates with the face of the cover 20 through a. lock washer 22. Thus the shaft I1 is mounted for rotational movement about its longitudinal axis.

In order to provide an improved arrangement for bridging between adjacent parts of the stationary contacts M, I provide bridging contacts 23. Any suitable number of bridging contacts may, of course, be employed, and of course any suitable number of stationary contacts may be also employed. In the application of my improved control device, which will hereinafter be described, I have found it convenient to provide two such bridging contacts 23, one contact, 2311, which cooperates with stationary contacts Ma, Nb, and I40, and the other, 23b, which cooperates with stationary contacts 14d, He and I. Since the stationary contacts i i are provided with substantially parallel faces it, it is, of course, desirable that they should be so mounted in their respective terminals l2 that all the faces l6 lie in the same plane. However, such a precise requirement does not lend itself to modern methods of large scale production, and thus it will be found that the faces l6 will usually lie in several planes, or in other words, their faces will be out of line. It therefore becomes necessary to provide an arrangement for mounting the bridging contacts 23 so that they may be able to make good electrical contact with the pair of stationary contacts M which are, at any particular time, being bridged. In order to accomplish this,

I have provided an improved mounting arrangement for the bridging contacts 23 which includes a pin, and blind hole connection so proportioned that the bridging contact may have a limited rocking movement. Thus I have provided on the shaft ll adjacent the stationary contacts M a bar 24 which may be made of any suitable material such as an insulating moldable material. Near the outside ends of the bar remote from the shaft I1 I provide metallic inserts 25. Extending from the inserts 25 I also provide pins 26. In order to receive the pins 26 I provide a cooperating blind hole 21 which extends part way in from one face of the bridging contact 23 as will be seen in Fig. '7. The bore of the hole or bearing surface 21 is so proportioned with respect to the pin 25 so as to allow the limited rocking movement of the contact 23. Thus the hole 21 is tapered so that its diameter is larger than the diameter of the pin 25 at the surface and it tapers so that its diameter decreases as the bottom of the hole is reached, the bottom being so proportioned that it snugly fits the end of the pin 26. The depth of the hole 21 is less than the length of the pin 26 by such an amount and the diameter of the hole tapers by such an amount that the desirable rocking action will obtain before the surface of the contact 23 facing the insert 25 touches the adjacent surface of the insert 25. The amount of limited rocking movement may be of course varied by varying the relative dimensions of the length and diameter of the pin and the depth and amount of taper of the hole. The contact faces of the bridging contacts 23 remote from the hole 21 are provided with contact faces 28 which are adapted to make contact with the faces l8 of adjacent stationary contacts 14, since a spring 29 forces the arm 24 in the direction of the stationary contacts. The contact faces 28 are thus substantially parallel with the contact faces l6.

Instead of employing a spring 29 which surrounds the shaft I1 and abuts against the arm 24 so as to bias both contacts 23 equally, a separate spring 29a, as will be seen in Fig. 8, may be employed between the arm 24 and an insert 25a which is slidably mounted in a recess 24a in the arm 24. With such a construction if the contact faces 28 of the contacts 23 wear different amounts, each will nevertheless be properly biased by its individual spring 29a.

In order that a different part of the contact face of the bridging contact may be presented to the cooperating stationary contact surface each time my control device is operated, I mount the stationary contacts on the circumference of a circle whose radius is different from the distance between the axis of the pin 26 and the axis of the shaft l1.

Thus let us assume that one of the bridging contacts 23 lies over the face of the stationary contact |4b. If the bridging contact is moved in a clockwise direction, looking at Fig. toward the contact M0, the edge of the bridging contact which is to make connection with the contact |4c may rock toward it if the contact face of the contact He is further away from the bridging contact than the contact faceof the contact l4b. Thus in spite of this unalignment of the stationary contacts I41; and He good contact will be made between the bridging contact and both the stationary contacts.

In order to provide an arrangement for holding the bridging contact in any suitable bridging position, such as when the contact 230 bridges the contacts Nb and Me, I provide the holding coil |3 which is in the casing adjacent the cover 20. As will be seen in Fig. 3 the coil [3 is annular in shape, surrounds the shaft l1, and is held in place by an annular sleeve member 30 of magnetic material which encloses the coil and is in turn supported by or integral with an angularly extending flange 3|. The flange is in turn supported by or is integral with an extending portion or bearing I 9. Thus when the nut 2|is screwed tightly against the face of the outside cover through the lock nut 22, it will intum hold the sleeve member and flange 3| tightly against the extend from the inside face of the cover 20 into a cooperating hole 33 of the sleeve 30 so that the sleeve may be positioned so that it will not rotate when the nut 2| is tightened. Referring more particularly to Fig. 4 there is illustrated the sleeve assembly and a pole piece 34 which is adapted to cooperate electromagnetically with the holding coil l3. This pole piece is held in place around a portion of the inside periphery of the sleeve member 30 by screws 35 and 36. An armature 31 is mounted on the shaft l1 and is adapted to cooperate with the pole face 340. of the pole piece 34 when the bridging contacts have been moved to the bridging position so as to hold the bridging contacts in their bridging position. Assuming therefore that the holding coil is energized when the contact 23a bridges contacts I41) and He and when 23b bridges contacts He and [4], the magnetic force between the armature 31 and pole face 34a will hold the contacts in the above mentioned position. This magnetic circuit may be traced through the following magnetic circuit: sleeve 30, flange 3|, shaft armature 31, pole piece 34, back again to the sleeve 30. A biasing spring 38 is also provided for returning the bridging contacts to a first position, such that they overlie the stationary contacts Nb and Me, after the circuit which includes the holding coil is broken.

It will'be observed that the pole piece 34 is a fragmentary ring-shaped member secured to the inside of one end of the cylindrical magnet core member 30 thereby partly to surround the shaft but in electromagnetic flux insulating spaced relation with the shaft. Thus the pole piece 34 leaves a circumferentially extending space by reason of its discontinuous structure between the core member 30 and the shaft. In this space the armature 31 is free to move, the armature extending substantially at right angles with respect to the shaft. Moreover, it will be seen that the pole face 34a is substantially parallel with the shaft, and likewise the coopcrating pole face on the armature 31 is substantially parallel with the shaft. These two pole faces come into abutting engaging the relation when the shaft is turned against the force applied by the spring, i. e., in a counterclockwise direction, as seen in Fig. 4.

My improved control device may be operated in any suitable manner, such as by an operating handle 39 which is attached to the shaft IT by means of a screw 40, and as I have stated my improved control device may be provided with any suitable number of stationary and cooperating bridging contacts, However, in the application which is diagrammatically illustrated in Fig. 9, five stationary contacts and two bridging contacts are required, contact |4d being of insulating material or removed since it is not needed. Thus in Fig. 9 I have diagrammatically inside face of the cover 20. A projection 32 may illustrated the connections between the stationary contacts and the control circuit necessary for effecting the feathering action of a propeller of an airplane, the stationary contacts being viewed from the left or terminal end of Fig. 3. Thus contact |4a is connected through a cable 4| to the normal propeller pitch control which includes a switch 42. The switch 42 may be either manually controlled or automatically controlled by any suitable device such as a governor. The switch 42 is connected to an electric motor 43 which is mounted to vary the propeller pitch. This motor may be of any suitable type such as a reversible one having forward and reverse field coils 44 and 45. The contacts of the switch 42 are connected to the field coils 44 and 45 through limit switches 46 and 41. Thus one of the limit switches may be automatically opened when low pitch is obtained and the other may be automatically opened when the propeller is feathered. Contact 8422 is connected to any suitable source of power such as a battery 48 through a cable 49. Contact Me is connected to a relay coil Mi which is designed to control a second source of power i through a cable 5'2. Thus when current flows through the relay coil 58 its contacts 53 will close so that a field coil 54 of the generator M will be energized. The contact lid is not needed and therefore it may be of insulating material, or it may be left out entirely and its terminal may be used to make a connection between one side of the coil l3 and the switch 42 through a connection 55 (see Fig. 2) and the cable 56. The terminal He is connected to the source of power 5i through the cable 51 and the terminal If is connected directly to the other side of the holding coil l3 through a connection inside the control device so that no cable needs to be connected to the terminal l4 The operation of my proved control device in its application to a feathering control circuit for a propeller will now be described. Let us assume the handle 39 is in a vertical position when the bridging contacts 23a and 23b overlie stationary contacts I41) and He respectively. When the handle 39 is rotated in a counterclockwise direction when looking at the right hand end of Fig. 3, or in a clockwise direction looking at Fig. 9, con tact 23a will bridge between contacts I44: and Nb. Thus a circuit will be made between the source 48 and the control switch 42. In order that the switch may be maintained in this position when it is desired to have normal feathering operation, or in its off position when desired, I provide a latch 58 (see Fig. 4) which is biased by a spring 59 to move into a groove 60 when the bridging contact 230: overlies the stationary contact 14b, that is the off position, but which moves into a groove 6! when the bridging contact 23a bridges between the stationary contacts Ma and Nb. However, if some condition obtains so that it is necessary to immediately feather the propeller, the pilot may move the operating handle 39 so that the bridging contact 23a will move from the above described position, over the contact Nb, and bridge between contacts l4b and I40. The contact 2322 will of course then bridge across contacts Me and I4). This will cause the relay coil 50 to be energized, so that the contacts 53 close, which will in turn energize the field 54 of the generator 5|. Thus current from the generator will flow to contact 14c. across the bridging contact 23b, to the stationary contact I41. The circuit may then be traced through the holding coil l3, connection 55, cable 56, to the feathering motor 43, through the control switch 42. It will thus be noted that the holding coil l3 will be energized so as to hold the bridging contacts in the latest described position. When the propeller has moved to its feathering position, the proper limit switch will open, thus breaking the holding coil circuit. With the holding coil deenergized the biasing spring 38 will rotate the shaft l1 until the latch 58 falls into the slot 60, at which time the control device will be in its open circuit or of! position.

In view of the foregoing it will be seen that I have provided a control device which may be manually moved to a first position where it may be mechanically held, and when manually moved to a second position it will be held there electrically. The device is also simple in construction, reliable in operation, and though of very small size, may control a relatively large value of current. In addition I have provided the feature which includes the pin and blind hole or bearing, as a mounting means for a bridging contact, which provides an improved arrangement for making good contact between the bridging contact and a pair of stationary contacts. This contact mounting arrangement is described and claimed in my above mentioned copending application.

Although I have shown and described particular embodiments of my invention, I do not desire to be limited to the particular embodiments described, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A control device comprising a plurality of stationary contacts, a rotatable shaft, a contact mounted on said shaft and movable with said shaft selectively into engagement with said stationary contacts, a magnet coil surrounding said shaft, said shaft forming part of a magnetic circuit for said coil, a pole piece for said coil spaced from said shaft having a pole face substantially parallel with said shaft, spring means for biasing said shaft to a predetermined angular position in which said movable contact is in engagement with a predetermined one of said stationary contacts, an armature mounted on said shaft and movable upon rotation of said shaft against the force applied by said spring means toward said pole face into abutting relation therewith to a position to be held by said pole piece with said movable contact in engagement with a second of said stationary contacts, and connections connecting said second stationary contact in circuit with said coil.

2. A control device including a plurality of stationary contacts, a rotatable shaft, a contact mounted on said shaft and movable with said shaft selectively into engagement with said stationary contacts, a magnet coil surrounding said shaft, means for supporting said coil in a fixed position, said shaft forming part of a magnetic circuit for said coil, an annular core member surrounding said coil forming part of a magnetic circuit for said coil, a fragmentary ring-shaped pole piece for said coil mounted inside of said annular member and partly surrounding said shaft in spaced relation therewith, said pole piece being discontinuous circumferentially thereby to leave a space between said shaft and said core member, spring means for biasing said shaft to a first angular position in which said movable contact is in engagement with a predetermined one of said stationary contacts, an armature mounted on said shaft in said space and movable upon rotation of said shaft against the force of said spring means toward said pole face into abutting relation therewith to a second angular position to be held by said pole piece with said movable contact in engagement with another of" said stationarycontacts, and releasable spring latching means on said shaft cooperating with the inner surface of said pole piece for holding said shaft in a third angular position.

3. A control device including a plurality of stationary contacts, a shaft, contact means mounted on said shaft and movable with said haftselectively into engagement with said stationary contacts, a magnet coil surrounding said shaft, connections for energizing said coil by said contact means when said shaft is turned to a predetermined position, a cylindrical magnet core member surrounding said coil and having one end in magnetic flux conducting relation with said shaft so that said shaft and said cylindrical member form part of a magnetic circuit for said coil, a fragmentary ring-shaped pole piece secured to the inside of the other end of said cylindrical core member, said pole piece partly surrounding said shaft in electromagnetic flux insulating spaced relation with said shaft and said pole piece being discontinuous circumferentially thereby to leave a circumferentially extending space between said shaft and said cylindrical core member, an armature mounted on said shaft extending at right angles with said shaft into said space thereby to provide for limited rotation of said shaft and a spring for biasing said shaft to a predetermined angular position in which said coil is deenergized by said contact means and said armature is in an unattracted position with relation to said pole piece, said armature being movable upon rotation of said shaft to said predetermined position against the force of said spring to an attracted position in which said coil is energized by said contact means and said armature is held magnetically by said pole piece against the force of said spring.

4. A control device including a plurality of stationary contacts, a shaft, contact means mounted on said shaft and movable with said shaft selectively into engagement with said stationary contacts, a magnet coil surrounding said shaft, connections for energizing said coil by said contact means when said shaft is turned to a predetermined position, a cylindrical magnet core member surrounding said coil and having one end in magnetic flux conducting relation with said shaft so that said shaft and said cylindrical member form part of a magnetic circuit for said coil, a fragmentary ring-shaped pole piece secured to the inside of the other end of said cylindrical core member having a pole face substantially parallel with said shaft, said pole piece partly surrounding said shaft in electromagnetic flux insulating spaced relation with said shaft and said pole piece being discontinuous circumferentially thereby to leave a circumferentially extending space between said shaft and said cylindrical core member, an armature mounted on said shaft extending at right angles with said shaft into said space thereby to provide for limited rotation of said shaft, a helical spring surrounding said shaft inside said coil for biasing said shaft to a predetermined angular position in which said coil is deenergized by said contact means and said armature is in an unattracted position with relation to said pole piece, said armature being movable by rotation of said shaft to said predetermined position against the force .of said spring to an attracted position in which said coil is energized by said contact means and said armature is held magnetically by said pole piece against the force of said spring, a spring pressed latching member on said shaft extending at right angles with said shaft in substantial alignment with said armature and having its outer end in engagement with the inner surface of said cylindrical core member, and latching projection means on said inner surface of said core member cooperating with said latch member to hold said shaft in said predetermined angular switching positions against the force of said spring.

LAURENS A. TAYLOR.

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