US2300993A - Control device - Google Patents

Description

Nov. 3, 1942. l.. A. TAYLOR 2,300,993

CONTROL DEVICE Filed June 19, 1940 :Lf/4f Inventor: /46

Laurens A. Taylor; b mmf dww 9 l-Iis Abtomeg.

Patented Nov. 3 1942 CONTROL DEVICE Laurens A. Taylor, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application June 19, 1940,` Serial No. 341,313

(Cl. ZOU-164)y 3l Claims.

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

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.

Another object of my invention is to provide an electric switch with an improved arrangement for mounting a bridging contact.

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 and eicient manner.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out in 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 4-4 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. l I have illustrated my improved control device having casings IFJ andv II. The casing or support l0 may be made of any suitable non-conducting material, such as a molded product so that a plurality of terminals I2 may be secured therein, as Will be seen in the sectional view of Fig. 3. The casing I I may be made of any suitable material, such as a cast metal and it provides an enclosure for the switch and its holding coil I3, as well as a mounting arrangement for the control device.

Each of the terminals I2 may be provided with a contact I4 which projects into a hollow portion I5 of the casing I0. The contacts I4 have parallel Acontact faces I6 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 I'I, as will be seen in Fig. 5. The shaft I'I is supported at one end in a hole I8 in the molded casing Ill and at the other end by a bearing I9 which is held in a hole in a cover part 20 of the casing I I. The bearing 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 I4 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, 23a, which cooperates with stationary contacts |40., I4b and I 4c, and the other, 23h, which cooperates with stationary contacts I4d, I4e and I4f. Since the stationary contacts I4 are provided with substantially parallel faces I6, it is, of course, desirable that they should be so mounted in their respective terminals I2 that all the faces I6 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 I 6 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 I4 which are, at any particular time, being bridged. In order to accomplish this, I have provided an improved mounting arrangement for the bridging contacts 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 I1 adjacent the stationary contacts I4 a bar 24, constituting an operating member, 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 Il 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 2,1 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 26 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 26 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 2T are provided with contact faces 28 which are adapted to make contact with the faces I6 of adjacent stationary contacts I4, 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 I6.

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 springZga, 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 2da 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 thc shaft I1.

Thus let us assume that one of the bridging contacts 23 lies over the face of the stationary Contact |419. If the bridging contact is moved in a clockwise direction, looking at Fig. 5, toward the contact Mc, the edge of the bridging contact which is to make connection with the contact hie may rock toward it if the contact face of the contact I4c is further away 'from the bridging contact than the contact face of the contact Mb. Thus in spite of this unalignment of the stationary contacts Mb and |40 good contact will be made between the bridging contact and both the stationary contacts.

In order to provide an arrangement for hold-- ing the bridging contact in any suitable bridging position. such as when the contact 23a bridges the contacts Mb and idc, I provide the holding coil I3 which is in the casing il adjacent the cover 20. As will be in Fig. 3 the coil I3 is annular in shape, surrounds the shaft i1, and is held in place by a sleeve member 3Q of magnetic material which is in turn supported by or integral with an angularly extending flange 3l. The flange is in turn supported by or is integral with an eitiending portion cr bearing I9. Thus when the nut 2i is screwed tightly against the face of the outside cover 2li through the lock nut 22, it will in turn hold the sleeve member 3D and iiange 3i tightly against the inside face of the cover 20. A

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' and the cable 5t.

projection 32 may extend from the inside iace of the cover 20 into a cooperating hole 33 of the sleeve 33 so that the sleeve may be positioned so that it will not rotate when the nut 2i is tightened Referring more particularly to 4 there is illustrated the sleeve assembly and a pole piece 34 which is adapted t0 cooperate electromagnetically with the holding coil I3. This pole piece is held in place around a portion of the inside periphery of the sleeve member 30 by screws 35 and 3G. An armature 3l is mounted on the shaft I1 and is adapted to cooperate with the pole face 3fm of the pole piece 3d 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 Mb and Mc and when 23h bridges contacts Ide and idf, 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 raced through the following magnetic circuit: sleeve flange 3|, shaft il, armature 37, 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 Mb and Ille, after the circuit which includes the holding coil is broken.

My improved control device may be operated in any suitable manner, such as by an operating handle 3B which is attached to the shaft Il 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, ve stationary contacts 'and two bridging contacts are required, Contact ldd being of insulating lmaterial or remove-d since it is not needed. Thus in Fig. 9 I have diagrammatically illustrated the connections between the stationary contacts and the control circuit necessary for effecting the feathering action of a propeller of an airplane,

i the stationary contacts being viewed from the left or terminal end of Fig. 3. Thus contact Ida is connected through a cable 4i 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 l2 is connected to an electric motor i3 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 M and 45. The contacts of the switch d2 are connected to the field coils 44 and 45 through limit switches 46 and 4l. 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 Mb is ccnnected to any suitable source of power such as a battery 48 through a cable 49. Contact Iflc is connected to a relay coil El! which is designed to control a second source of power 5i through a cable 52. Thus when current news through the relay coil 50 its contacts will close so that a field coil of the generator 5i will be energized. The contact idd 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 i3 and the switch i2 through a connection 55 (see Fig. 2) The terminal Ille is connected to the source of power 5! through the cable 5'! and the terminal Ilif is connected directly to the other side of the holding coil I3 through a connection inside the control device so that no cable needs to be connected to the terminal M.

The operation of my improved 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 3a. and 23o overlie stationary contacts Mb and |46 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, contact 23a will bridge between contacts Ma and Mb. 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 norm-al feathering operation, or in its 01T position when desired, I provide a latch 58 (see Fig. 4) which is biased by a spring 59 to move into a groove 6G when the bridging contact 23a overlies the stationary contact Mb that is the on" position, but which moves into a groove l when the bridging contact 23a bridges between the stationary contacts Ida and Mb. 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 Mb, and bridge between contacts Mb and |4c. The contact 23hl will, of course, then bridge across contacts Me and I4f. This will cause the relay coil 59 to be energized, so that the contacts 53 close, which will in turn energize the field 5d of the generator 5I. Thus current from the generator will ow to contact Me, across the bridging contact 23?), to the stationary contact Hij. The circuit may then be traced through the holding coil I3, connection 55, cable 56, to the feathering motor 43, through the control switch 42. It will thus be noted that the holding coil I3 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 33 will rotate the shaft l1 until the latch 58 falls into the slot E0, at which time the control device will be in its open circuit or off position.

In View of the foregoing it will be seen that I have provided a control device which may be manually moved to a rst 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 these features of the control device structure being described and claimed in my copending application, S. N. 396,323, which is a division of this application. 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.

The electromagnetic control device described herein is claimed in my copending divisional application Serial No. 396,323, led June 2, 1941.

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. In an electric switch, stationary contacts, a movable contact for bridging between said stationary contacts so as to make electrical connection therebetween, means for mounting said bridging contact for rotation about its longitudinal axis, means for mounting said rotatably mounted contact for bodily rotation about a center, said stationary contacts being mounted on the are of a circle whose radius is different from the distance between said longitudinal axis and said center of bodily rotation of said bridging contact so that movement of said bridging contact across said stationary contacts into bridging position will cause limited rotation of said bridging contact about its longitudinal axis.

2. An electric switch comprising a support, a plurality of stationary contacts mounted on said support in spaced relation with each other on the circumference of a circle, a contact operating member pivotally mounted on said support for rotation about an axis, a movable contact, a pin and blind hole connection mounting said movable contact on said operating member for cooperation with said stationary contacts and a predetermined distance from said axis different from the radius of said circle so that sliding movement of said movable contact over said stationary contacts upon rotation of said operating member produces a limited rotation of said movable contact on said pin connection thereby to present different parts of said movable contact to said stationary contacts.

3. An electric switch comprising a support, a plurality of stationary contacts mounted on said support in spaced relation with each other on the circumference of a circle, a contact operating member pivotally mounted on said support for rotation about an axis passing through the center of said circle, a plurality of movable bridging contacts, pin and blind hole connections mounting said movable contacts on said operating member for cooperation with said stationary contacts and in spaced relation with each other on the circumference of a circle whose center lies on said axis and whose radius is different from the radius of said first circle so that sliding movement of said movable contacts over said stationary contacts upon rotation of said operating member produces a limited rotation o1' said bridging contacts on said pin connections thereby to present different parts of said bridging contacts to said stationary contacts.

LAURENS A. TAYLOR.

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