US2996694A - Rotary arm contactless switch - Google Patents

Description

Aug. 15, 1961 N. BERMAN ROTARY ARM CONTACTLESS SWITCH 2 Sheets-Sheet 1 Filed July 29, 1957 Q mh ww ww Q ww E w ww \w Q Q- mm vw E N O w Q 6% v vw NM 0 I N QM NM ow HQ WM NW 1 1 I wm N v wN bx vm United States Patent 2,996,694 ROTARY ARM CONTACTLESS SWITCH Nelson Berman, New Hyde Park, N.Y., assignor, by mesne assignments, to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Filed July 29, 1957, Ser. No. 674,735 3 Claims. (Cl. 336.120)

My invention relates to a rotary arm contactless switch and more particularly to a rotary arm contactless switch for sequentially sampling voltage analogues of a number of respective physical variables.

It is often necessary or desirable to provide an indication at a central station of a number of physical variables measured at respective remote locations. Various means are known in the prior art which provide a voltage analogue of a physical variable being measured. These voltage analogues may readily be conducted to a central station at which they are to be read. In the prior art rotary switches having interengageable, relatively movable brushes and contacts are known for sequentially sampling a plurality of respective voltages applied to the switch contacts. After a period in operation of these switches of the prior art the brushes become worn and must be replaced. The contacts of the switches, which are formed of a conducting material such as copper, become dirty in use and require frequent cleaning. If proper maintenance is not given the switches of the prior art at relatively frequent intervals false indications will be provided by the switches. Further, the brushes and contacts of these switches of the prior art are likely to become disarranged as a result of shock forces applied to the switch.

I have invented a rotary arm contactless switch for sequentially sampling voltage analogues of a number of physical quantities being measured. In my switch there is no direct physical engagement between the moving and stationary members. My switch does not use the brushes and contacts of switches of the prior art. My switch is extremely rugged and reliable. It requires very little maintenance even after a long period of time in operation.

One object of my invention is to provide a rotary arm contactless switch for sequentially sampling voltage analogues of a number of physical variables being measured.

Another object of my invention is to provide a rotary arm contactless switch in which there is no direct physical contact between the moving and stationary switch elements.

A further object of my invention is to provide a rotary arm contactless switch which does not employ the relatively movable brushes and contacts of sampling switches of the prior art.

Yet another object of my invention is to provide a rotary arm contactless switch which is rugged and reliable.

A still further object of my invention is to provide a rotary arm contactless switch which requires little maintenance even after a long period of time in use.

Other and further objects of my invention will appear from the following description:

In general my invention contemplates the provision of a rotary arm contactless switch for sampling a plurality of voltage analogues including a number of respective primary windings carried by teeth formed of magnetic material fixed on a stationary support. I impress the respective voltage analogues on the primary windings. A member movable with respect to the stationary member supports a secondary winding. The movable member is adapted to be moved to pass the secondary winding through the respective primary winding magnetic ice fields produced by the voltage analogues. As the movable member moves the secondary winding through the primary winding fields, a plurality of respective voltages having magnitudes proportional to the physical variables are induced in the secondary winding. My switch includes means carried by the movable member for completing the primary winding flux paths.

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals indicate like parts in the various views:

FIGURE 1 is a sectional view of one form of my rotary arm contactless switch.

FIGURE 2 is a sectional view of the form of my contactless switch shown in FIGURE 1 taken along the line 22 of FIGURE 1 with parts removed.

FIGURE 3 is a development of a multiple form of my contactless switch with parts shown in section.

Referring now more particularly to FIGURES 1 and 2 of the drawings, my rotary arm contactless switch includes a stationary ring 10 supported in the switch housing I2 by any convenient means such as brackets I4 and 16. I form ring 10 from a diamagnetic material such as plastic, or the like, and provide the ring with a plurality of threaded bores 18 spaced around the ring. A plurality of respective teeth 20 formed of magnetic material and screwed into the ring bores 18 carry a plurality of respective primary windings 22. Pairs of conductors 24 and 26 connect windings 22 to devices (not shown) known in the art for producing respective voltage analogues of physical quantities being measured. It will be appreciated that the voltage analogues generate respective currents in windings 22 to produce fluxes in the teeth '20.

I mount a hub 28 by means of a key or the like 30 on a shaft 32 rotatably supported in housing 12 by a bearing 34. An arm 36 formed on hub 28 carries a secondary winding 38 to which I connect respective conductors 4t) and 42. Winding 38 is positioned to pass through the magnetic fields of the respective primary windings 22 as shaft 32 rotates. I form hub 28 with a radially extending arm 44 provided at its end remote from hub 28 with a laterally extending portion 46. This arm 44 with its portion 46 provides a path for the flux from the primary winding adjacent which the secondary winding 38 is disposed at any particular time. It is to be understood that arm 36, hub 28 and arm 44 are formed from a suitable magnetic material. As hub 28 rotates, winding 38 sequentially passes through the respective fields of the teeth 20 to generate respective voltages in winding 38. These generated voltages may be conducted from conductors 40 and 42 by any convenient means known to the art such, for example, as slip rings and brushes or a magnetic coupling. The current flowing through each of the respective windings 22 is proportional to the voltage analogue applied to the winding. The flux in each tooth is proportional to the winding current. The signal induced in the secondary winding 38 as it passes a given tooth 20 is proportional to the field strength of the tooth fiux. It will be seen that the voltage induced in secondary winding 38 as it passes by a tooth 20 is proportional to the voltage analogue fed to the primary winding carried by the tooth.

Referring now to FIGURE 3, I have shown a multiple form of my rotary arm contactless switch. This form includes a plurality of respective rings 48, 50, 52, and 54 of nonmagnetic material each of which rings carries a plurality of spaced teeth 20 of magnetic material. Each tooth 20 carries a winding 22. It is to be noted that the respective teeth of the rings 48, 50, 52 and 54 are staggered with respect to each other. I provide respective Secondary windings 56, 58, 6t) and 62 adapted to be passed through the primary magnetic fields of the respective rings 48, 50, 52 and 54. The windings 56, 58, 60 and 62 are carried by arms 36 fixed on a common shaft 63 shown in phantom in FIGURE 3 rotatably supported in the fixed housing 65. An arm 44 having a portion 46 is associated with each of the windings 56, '58, 60 and 62. Owing to the staggered arrangement of the magnetic teeth in the multiple form of my switch, a series of spaced pulses equal to the total number of teeth will be produced. I employ respective conductors 64, 66 and 68 to connect secondary windings 56, 58, and 62 in series. Respective conductors 70 and 72- connected to windings 56 and 62 carry the output signals of all the windings 56, 58, 60 and 62 to the external circuit. Conductors 70 and 72 carry a series of spaced signals equal to the total number of teeth 20 in the multiple form of my switch.

In operation of the form of my invention shown in FIGURE 2, respective pairs of conductors 24 and 26 impress voltage analogues of the physical variables to be measured on the primary windings 22. These voltage analogues may be direct current or alternating current. If direct current analogues are employed, a respective alternating cycle is induced in winding 38 each time the winding passes a tooth 20 as shaft 32 rotates. The magnitude of each signal is proportional to the magnitude of the input signal, the velocity of the rotating arm and the flux density underneath each tooth. If alternating current analogues are employed, the voltages induced in winding 38 will appear as amplitude modulated voltages. The amplitude of the envelope of each of these output voltages is a maximum when portion 46 of arm 44 is directly over a winding 22. The envelope amplitude decreases to its minimum value as arm 44 leaves the magnetic field of the winding. The output signal magnitude also depends on the speed of shaft 32 and the frequency of the alternating current analogue.

It will be understood that when a direct current or an alternating current analogue is employed, in each case the output signals have magnitudes proportional to the respective magnitudes of the voltage analogues.

The operation of the multiple form of my switch shown in FIGURE 3 is similar to the operation of the form shown in FIGURES 1 and 2. In this case, however, owing to the staggered arrangement of the teeth 20 a plurality of respective signals proportional to the voltage analogues is produced on conductors 70 and 72.

It will be seen that I have accomplished the objects of my invention. I have provided a rotary arm contactless switch for sequentially sampling respective voltage analogues of a plurality of physical variables. In my switch there is no direct physical engagement between the stationary and the movable members. My switch does not include brushes and contacts of the type used in the prior art. It is extremely rugged and reliable in operation. My switch requires very little maintenance even after a long period of time in use.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, What I claim is:

1. A contactless switch for sampling a plurality of voltage analogues of respective physical variables includ ing in combination a stationary support ring formed of diamagnetic material, a plurality of radially extending core teeth formed of magnetic material carried by said support ring, respective primary windings carried by said core teeth, a rotor, means mounting said rotor for movement about the axis of said ring, a radially extending core tooth formed of magnetic material carried by said rotor, a secondary winding carried by said rotor core tooth, said rotor being adapted to be driven successively to align said rotor core tooth individually with each one of said stator core teeth, a radially extending arm formed of magnetic material and means mounting said arm on said rotor in spaced relation in the direction of said axis to said rotor core for movement with said rotor, said arm extending to a position adjacent and end of a stator tooth with which said rotor tooth is aligned to complete a path for flux passing through said rotor core tooth and said aligned stator core tooth.

2. A contactless switch for sampling a plurality of voltage analogues of respective physical variables including in combination a stationary support ring formed of diamagnetic material, a plurality of radially extending core teeth formed of magnetic material carried by said support ring, respective primary windings carried by said core teeth, a rotor, means mounting said rotor for movement about the axis of said ring, a radially extending core tooth formed of magnetic material carried by said rotor, a secondary winding carried by said rotor core tooth, said rotor being adapted to be driven successively to align said rotor core tooth individually with each each one of said stator core teeth, a radially extending arm formed of magnetic material and means mounting said arm on said rotor in spaced relation in the direction of said axis to said rotor core tooth for movement with said rotor, said arm extending to a position adjacent an end of a stator tooth with which said rotor tooth is aligned to complete a path for flux passing through said rotor core tooth and said aligned stator core tooth and including an offset portion extending in an axial direction over the end of said aligned stator tooth.

3. A contactless switch for sequentially sampling re spective voltage analogues of a plurality of physical variables including in combination a stator formed of diamagnetic material, a plurality of respective coaxial rings of spaced radially extending teeth of magnetic material carried by said stator, the teeth of each ring being staggered with respect to the remaining rings, respective primary windings carried by said teeth, means impressing the respective voltage analogues on said primary windings to produce magnetic fields in said teeth, a rotor, means mounting said rotor for movement about the axis of said rings, a plurality of radially extending rotor core teeth formed of magnetic material, means mounting said rotor teeth in axially spaced relationship on said rotor for cooperation with the respective rings of stator core teeth, respective secondary windings carried by said rotor core teeth, said rotor being adapted to be driven successively to align each of said rotor teeth individually with the stator core teeth of the associated ring, respective radially extending arms formed of magnetic material, and means mounting each of said arms on said rotor in spaced relation in the direction of said axis to a rotor core tooth for movement with said rotor, each of said arms extending to a position adjacent an end of a stator tooth with which the corresponding rotor tooth is aligned to complete a path for flux passing through the rotor core tooth with which it is associated and said aligned stator core tooth.

References Cited in the file of this patent UNITED STATES PATENTS 344,318 Jones June 22, 1886 739,572 Armstrong Sept. 22, 1903 1,984,939 Nachumsohn Dec. 18, 1934 2,459,704 Johnson Jan. 18, 1949 2,786,182 Herbert Mar. 19, 1957 2,807,756 Cronin Sept. 24, 1957 FOREIGN PATENTS 21,680 Great Britain Sept. 23, 1915 of 1914

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