US2988616A

US2988616A - Switch assembly

Info

Publication number: US2988616A
Application number: US753041A
Authority: US
Inventors: Glenn A Reese
Original assignee: Magnavox Co
Current assignee: Philips North America LLC
Priority date: 1958-08-04
Filing date: 1958-08-04
Publication date: 1961-06-13
Anticipated expiration: 1978-06-13

Description

June 13, 1961 G. A. REESE SWITCH ASSEMBLY 5 Sheets-Sheet 1 Filed Aug. 4, 1958 5 Sheets-Sheet 2 I IN @L G. A. REESE SWITCH ASSEMBLY uuy June 13, 1961 Filed Aug. 4, 1958 June 13, 1961 REESE 2,988,616

SWITCH ASSEMBLY Filed Aug. 4, 1958 5 Sheets-Sheet 3 June 13, 1961 e. A. REESE SWITCH ASSEMBLY Filed 4, 195a 5 Sheets-Sheet 4 June 13, 1961 Filed Aug. 4, 1958 G. A. REESE 2,988,616

SWITCH ASSEMBLY 5 Sheets-Sheet 5 United States Patent 2,988,616 SWITCH ASSEMBLY I Glenn A. Reese, Canoga Park, Calif., assignor to The Magnavox Company, Los Angeles, Calif., a corporation of Delaware Filed Aug. 4, 1958, Ser. No. 753,041 15 Claims. (Cl. 200-90) The invention relates to magnetically operated switching assemblies and more particularly to a new and improved switching assembly of this general type which is capable of rapid and noise-free operation.

Many types of present day electronic and electrical equipment require switching assemblies which will operate at an extremely high rate of speed and which are capable of noise-free operation. Moreover, this type of equipment often requires that the switching operations be performed at precisely timed intervals. The prior art, for the most part, has failed to provide switching assemblies adequate for these purposes and which can be constructed at a reasonably low cost.

Copending application Serial No. 652,968 filed April 15, 1957 now Patent No. 2,945,931 in the name of the present inventor, ho'wever, discloses and claims an improved switching assembly in which most of the prior art problems in this area have been solved. The switching as sembly disclosed in the copending application includes at least one switching unit which is mounted to extend into an annular air gap. A magnetic flux is produced in the air gap, and precisely defined variations are introduced into the flux at accurately positioned locations. Relative motion is produced between the fiux in the air gap and the switching unit so that the variations in the flux may be swept past the unit so as to actuate a magnetic armature in the unit. By providing a relatively large number of similar switching units in the air gap, and by the provision of several spaced variations in the fiux, it is clear that a large number of switching operations can be produced in each operating cycle of the switching assembly.

Copending application Serial No. 656,054, which was filed April 30, 1957 now Patent No. 2,932,699, in the name of the present inventor, provides a switching assembly of the same general type as that of the first copending application 652,968, now Patent No. 2,945,931, and as described above. The assembly of the latter copending application is of somewhat simplified construction as compared with the former, and the latter assembly also includes means for compensating for unwanted noise which may sometimes be produced in the active elements of the switch during the switching operation. This unwanted noise may occasionally appear, for example, in the armatures of the switching units of the copending application in the form of pulses. These pulses are developed as the switching units pass through the switchactuating variations in the magnetic tfiux of the air gap and appear in the circuitry associated with the units. The pulses have proven to be troublesome in some applications in which the assemblies of the copending applications have been used.

The apparatus of the later application Serial No. 656,054, now Patent No. 2,932,699, is constructed to provide a compensating variation in the magnetic flux of the air gap for each switch actuating variation in order to cancel the noise pulses referred to above. Also, the apparatus of the later copending application incorporates other features for reducing the amplitude of these noise pulses to a minimum.

An objective of the present invention, as of the copending application 656,054, now Patent No. 2,932,699 is to eliminate the production of noise pulses of the type described above. In the present invention, the armature of each switching unit is insulated from the casing and 2,988,616 Patented June 13, 1961 this armature supports the movable contact of the unit. The switching unit may, for example, be a single-pole single-throw type and its fixed contact is also insulated from the casing. This enables the casing to function as a shield, and even though noise pulses are produced on the casing as the unit is swept through the variations in the magnetic flux, such noise pulses do not enter the electrical circuitry controlled by the contacts of the switching unit.

In one of the embodiments of the invention to be described, the magnetic armature of the switching unit is pivotally supported within the casing of the unit by means of a film of oil which surrounds an insulating collar on the armature. The movable contact is cupshaped and is supported at the free end of the magnetic armature. A pilot tube is insulatingly supported within the unit and is positioned to extend along the longitudinal axis into a loose mechanical coupling engagement with the movable contact. This pilot tube limits the movement of the movable contact and assures that neither the movable contact nor the magnetic armature will touch the side of the casing. A connection to the movable contact is conveniently made by a control wire which extends down through the pilot tube.

In another embodiment of the invention to be described, a pair of fixed contacts are supported within the switching units to provide for single-pole, double-throw action. This pair of fixed contacts and a third unused contact are positioned to surround the movable contact and limit its movement. This prevents the movable contact from touching the side of the unit.

The switching units of the embodiments to be described have fixed contacts with a rod-like configuration and are supported by the same insulating members which support the pilot tubes. The fixed contacts are held in essentially parallel relation with their respective pilot tubes, and the end of each of the fixed contacts adjacent its corresponding movable contact is inclined so that the gap between the fixed and movable contacts can be adjusted by adjusting the axial position of the movable contact.

The axial position of the movable contact can conveniently be established during fabrication of the unit by pulling or pushing the central wire connected to that contact through the pilot tube. This causes the entire armature to move up or down on its oil base. When the desired gap between the fixed and movable contacts is established, the pilot tube may be crimped to the central wire to hold the latter and, therefore, the armature and movable contact against any further axial movement. This is a most important feature of the switching units of the invention since it permits practical and commercially feasible construction methods to be practiced in the fabrication of the units.

The over-all switching assembly of the invention has a feature in that the outer housing is constructed to allow a plurality of similar assemblies to be stacked coaxially in a banked relation with all the assemblies being driven by the same motor. This provides a multiple of related switching operations which can be precisely timed with respect to one another, and which can have any desired phase relation merely by adjusting the relative angular positions of the individual switching assemblies in the stack.

The individual switching assembly of the invention may also include a plurality of axial inscriptions or etchings on the peripheral surface of its magnetized rotor. These inscriptions may then be read by one or more transducer means mounted on the housing of the switching assembly. The resulting output signals from the transducer means can have a duration less than the duration of each switching operation and an output pulse from the transducer can be used in conjunction with the actual switching operation to synchronize the operation of the switching units. Any residual noise pulses of the type described above appear usually at the beginning and end of each switching operation corresponding to the closing and the opening of the contacts of any particular switching unit. The pulses from the transducer can be made to correspond to each switching operation of thee assembly and to occur at an interval between the closure and opening of the contacts of switching units so as to be unaffected by the noise pulses. The pulses from the transducer, rather than a switching operation itself, can then be used to actuate the circuitry controlled by the assembly with the switching operation serving merely to close an appropriate gate for the transducer pulse. This assures with a high degree of certainty that no extraneous noise pulses will be inserted into the circuitry controlled by the switching assembly. The position of the pulse from the transducer with respect to the corresponding switching operations can be controlled and adjusted by providing for a limited angular adjustment of the transducer with respect to the housing, as will be described.

Other features and advantages of the switching assembly of the invention will become evident from the following description of one particular embodiment of the invention.

In the drawings:

FIG. 1 is a perspective view of a magnetically operated switching assembly constructed in accordance with the invention, this view showing the manner in which the switch housing is secured to a motor housing and how a plurality of transducer heads may bemounted on the switch housing, this view also showing a plurality of terminal connections for the different switching units included in the assembly extending through a rim of the switch housing to permit stacking of a plurality of like assemblies, one over the other;

FIG. 2 shows a multi-bank unit including a plurality of switching assemblies, each constructed in accordance with the invention and similar to the assembly of FIG. 1, with the multi-bank unit of FIG. 2 including a plurality of separate switching assemblies supported in coaxial relation and driven by a single motor;

FIG. 3 is a side elevational view of the switching assembly of FIG. 1 and showing the terminal connections for the switching units in the assembly, this view also showing one of the transducer heads of the unit and the clamping means whereby the switching assembly is mounted on a suitable driving motor;

FIG. 4 is a sectional view taken substantially on the line 4-4 and showing the internal components of the switching assembly and further showing in block form certain electrical stages associated with the switching unit; specifically, the latter view shows the manner in which a plurality of separate magnetically operated switching units are supported within the assembly, and it also shows constructional details of a magnetic rotor which successively actuates the different individual switching units;

FIG. 5 is a top plan view of the switching assembly of FIG. 4 and illustrates a removable top to the switching assembly which can be removed when it is desired to stack other similar assemblies in a banked relation in the manner shown in FIG. 2;

FIG. 6 is a cross-sectional view substantially on the line 66 of FIG. 4 and showing the configuration of the pole pieces of the magnetic rotor of the switching assembly which define an annular air gap having variations in the magnetic flux produced therein at selected positions to produce the desired actuations of the different individual switching units;

FIG. 7 is a side sectional view of one o f the switching units to be supported in the switching assembly, this view showing the internal components of the switching unit on an enlarged scale for purposes of clarity;

FIGS. 8A and 8B are schematic representations of the air gap formed by the rotor pole pieces of the switching assembly, these views illustrating the manner in which a movable contact in each switching unit is brought into contact with a fixed contact in the unit as that particular switching unit is swept by a variation in the magnetic flux in the air gap;

FIG. 9 is a side sectional view of a modified type of switching unit to be supported in the switching assembly, this latter type of switching unit providing single-pole, double-throw action;

FIG. 10 is an elemental circuit diagram of a switching circuit in which the switching assembly of the in vention, utilizing modified switching units of the type shown in FIG. 9, finds great utility; and

FIG. 11 is a fragmentary cross-sectional view of the switching assembly to show a simplified electromagnetic pickup and how it cooperates with inscriptions on the rotor of the switching assembly to provide timing pulses.

The magnetically operated switching assembly of the present invention in the first embodiment to be described includes a plurality of separate single-pole, single-throw switching units which are supported in the body of the switching assembly and which are successively actuated as a magnetic rotor in the switching assembly is rotated by a drive motor. As noted above, each individual switching unit is actuated by a variation in the magnetic flux in an air gap formed in the magnetic rotor. In a constructed embodiment of the invention, the rotor has been driven at a speed of 30 revolutions per second and two variations have been provided in the magnetic flux produced in the annular air gap. Therefore, each individual switching unit has been actuated at a rate of 60 times a second.

The magnetically operated switching assembly of FIG. 1 includes a generally cylindrical switch housing 10 and a cylindrical adapter housing 12. The adapter housing 12 has a lower portion of reduced diameter with respect to its upper portion. The lower portion has a diameter corresponding to the diameter of a drive motor 14, and it is secured to the drive motor by a plurality of screws, such as the screws 16. The upper portion of the adapter housing has a diameter corresponding to the diameter of the switch housing, and the upper portion has a rim 18 at its extremity of increased outer diameter. The switching housing has a lower rim 20 of the same outer diameter as the rim 18. A clamp 22 extends around these

rims

18 and 20, and a usual buckle, or fastener, arrangement 24 serves to hold the clamp securely in place. Therefore, when the buckle is closed, the switch housing 10 and the adapter housing 12 are securely held together. However, these housings may be separated and the switch housing removed, merely by opening the buckle 24.

A pair of

transducers

26 and 28 are secured to the peripheral surface of the switch housing 10. The transducers are secured to the peripheral surface of the switch housing by a plurality of screws 30. Each of the transducers is slotted to receive the screws 30, and this permits an angular adjustment within certain limits of each transducer on the peripheral surface of the switch housing. The

transducers

26 and 28 are of any usual electromagnetic type, and their sensing faces extend through the switch housing 10 into magnetically coupled relationship with the periphery of the magnetic rotor of the switch assembly. In a manner to be described, as the magnetic rotor rotates, these transducers successively sense a plurality of axial inscriptions or etchings which are formed on the peripheral surface of the magnetic rotor at spaced angular positions.

The switch housing 10 has a rim portion 10a at its up per end, and a plurality of mutually insulated electrical terminals 32 extend in a radial direction through this rim. These terminals are connected to individual ones of a plurality of magnetically operated switching units which are included within the switching assembly andwhich assume will be described. The upper end of the switching assembly of FIG. 1 is covered by a disk-like cover 34 which is secured to the switch housing by a plurality of screws 36. When it is desired to bank a plurality of the switching assemblies in the coaxial relation of FIG. 2, the cover 34 is removed, and a second switching assembly is held in place by a clamp and buckle arrangement similar to the

elements

18 and 24. This is repeated for as many switching assemblies as are desired in the bank. The view of FIG. 2, for example, shows a group of three separate switching assemblies supported on the common adapter bracket 12 of the motor 14. These switching assemblies are designated in FIG. 2 as 40, 42 and 44. A clamp and buckle arrangement 46 secures the switching assembly 40 to the adapter housing 12'. In like manner, a clamp and buckle assembly 48 serves to clamp the switching assembly 42 to the top of the switching assembly 40. Likewise, a clamp and buckle arrangement 50 secures the switching assembly 44 to the top of the switching assembly 42. The

switching assemblies

40, 42 and 44 include respective transducers, such as the transducers 52, 54 and 56, corresponding to the

transducers

26 and 28 referred to previously. The switching assembly 44 is provided with a cover 58' similar to the cover 34 of the assembly of FIG. 1.

In the switching bank of FIG. 2, the number of switching operations is multiplied by the number of separate switching assemblies in the bank, as the different switching assemblies are all driven by the motor 14'. Also, desired phase relations may be obtained between the switching operations of the different switching assemblies in the bank of FIG. 2, merely by adjusting the relative angular positions of the

different switching assemblies

40, 42 or 44.

The switch housing 10 and the adapter housing 12, as well as the clamp 18 and the cover 34, may all be composed, for example, of an aluminum alloy or other nonmagnetic material. The motor 14 in a constructed embodiment of the invention is a synchronous motor. However, a direct-current motor may be used to advantage since such a motor may be made smaller than a corresponding synchronous motor. As noted above, the motor in the constructed embodiment of the invention drives the switch rotors at a rate of 30 revolutions per second.

As shown more clearly in FIG. 4, for example, the motor 14 includes a shaft 60 which is composed preferably of stainless steel or other nonmagnetic material. This is so that the shaft will not tend to shunt the magnetic field set up in the rotor of the switching assembly.

The switch housing 10 has a lower end portion 62 which is provided with an essentially disk-like configuration and a peripheral rim 64 of reduced axial thickness. This rim is engaged by an annular channel formed by the lower rim of the switch housing 10 and by the upper rim 18 of the adapter housing 12. The end portion 62 of the housing 10 is also composed of aluminum or other nonmagnetic material. The switch housing 10 also has an upper end portion 66 of a disk-like configuration and, likewise, composed of aluminum or other nonmagnetic material. The lower end portion 62 of the housing has a central aperture which supports a bearing 68. The upper end portion 66 likewise has a central aperture, and this central aperture is disposed in axial alignment with the central aperture of the lower end portion 62. The central aperture of the upper end portion 66 supports a bearing 70.

A central shaft 72 composed of nonmagnetic material, such as stainless steel, is rotatably supported in the bearings 68 and 70. The shaft 72 is in axial alignment with the motor shaft 60, and an appropriate coupler 74 couples the motor shaft 60 to the rotatable shaft 72. The upper portion of the shaft 72 is provided with a tongue 76, the tongue being adapted to receive a coupler similar to the coupler 74 so that other similar shafts of similar switching assemblies may be coupled to the motor shaft for the banked arrangement of FIG. 2.

A lower pole piece 78 composed of magnetic material such as iron is secured to a shoulder on the shaft 72 by 'a plurality of screws such as the screw 80. This lower pole piece has a centrally apertured disk-shaped portion through which the screw 80 extends and which is adjacent the lower end portion 62 of the switch housing. The lower pole piece also has a cylindrical portion which may be integral with the disk-shaped portion. The cylindrical portion of the lower pole piece extends axially upwardly adjacent the inner peripheral surface of the switch housing 10. An axially-magnetized ring-shaped permanent magnet 82 is supported on the disk-shaped portion of the lower pole piece 78 in coaxial relation with the shaft 72. The permanent magnet 82 has an outer diameter which is less than the inner diameter of the cylindrical portion of the lower pole piece.

A centrally-apertured disk-shaped upper pole piece 84, composed of iron or other magnetic material, is fastened to a shoulder on the shaft 72 by a plurality of screws such as the screw 86. This upper pole piece serves as the second pole piece for the permanent magnet 82, and the permanent magnet is sandwiched between the

pole pieces

78 and 84. The cylindrical portion of the pole piece 78 is spaced radially from the outer peripheral surface of the permanent magnet 82, as shown, and the upper pole piece 84 projects radially beyond the peripheral surface of the permanent magnet.

A ring-shaped member 88 is secured or is integral with the upper rim of the cylindrical portion of the lower pole piece 78. The ring-shaped member 88 is composed of a magnetic material such as iron, and it is in uniplanar relation with the disk-shaped upper pole piece 84. The outer rim of the pole piece 84 and the inner rim of the ring-shaped member 88 are spaced radially from one another. These rims define an annular air gap 90 which is best shown in FIG. 6. It is apparent that when the motor shaft 60 drives the shaft 72, the permanent magnet 82 is rotated, together with its upper and

lower pole pieces

84 and 78.

It will be appreciated that the pole piece 78 and the pole piece 84 can also be formed so that they are spaced axially from each other to define an air gap instead of being formed to define the radial air gap shown in FIG. 2. As will become fully apparent subsequently, an axial air gap is equivalent to a radial air gap provided that the switching unit shown in FIG. 7 is properly positioned to extend into the air gap.

A plurality of angularly spaced, axially extending inscriptions are etched, or otherwise formed, on the outer peripheral surface of the cylindrical portion of the lower pole piece 78. These inscriptions are schematically illus trated at 79 in FIGS. 4 and 6. The faces of the

transducers

26 and 28 are brought into magnetically coupled relationship with this peripheral surface of this cylindrical portion of the pole piece. Then, as the rotor is rotated, each inscription 79 causes a variation in the lines of flux linking the respective transducers, so that an electric current pulse is produced by each transducer in response to the passage of an inscription. The inscriptions 79 are preferably made to correspond to the actuation of each switching unit in the assembly, so that each such switching unit has, in eifect, a corresponding inscription on the pole piece 78 for each of its actuations.

The signals produced in the

transducers

26 and 28 by the inscriptions, therefore, correspond to clock signals to synchronize the operation of the signals produced by the switching units in controlling the operation of subsequent stages. By way of illustration, the signals produced in the transducer 28 may be introduced to a gate 81 in FIG. 4, as may be the signals produced in any particular one of switching units 110. The gate 81 then operates to pass a signal only in the portion of the signal produced by the gate in which the signal produced by the switching unit is not afiiected by transient conditions. This occurs at the time that a signal is produced by the transducer 28. In this way, the switching unit 110, in effect, prepares the gate 81 to become opened so that the signal from the transducer 28 can then pass through the gate.

It is evident that the axially magnetized magnet 82 develops a magnetic flux in the annular air gap 90' between the

pole pieces

84 and 78. Because one of these pole pieces represents a north pole and the other a south pole, the lines of flux flow generally in a radial direction and uniformly across the air gap 9%. However, the ring portion 88 of the pole piece 78 is provided with a pair of radially inwardly extending tongues 1th) and 1412, and the pole piece 84 is provided with a pair of inwardly extending

radial grooves

104 and 106 positioned adjacent corresponding ones of the tongues. These tongues and grooves serve to produce variations in the flux across the air gap 90, and also to produce local distortions in the flux in their vicinity. When a stationary switching unit is mounted to extend into the rotating annular air gap 90, a magnetic armature included in the switching unit moves as the unit is swept by the flux in the portion of the air gap corresponding to the tongue and groove 100, 1414 and when it is swept by the flux in the portion corresponding to the tongue and groove 1J2 and 106.

As shown in FIG. 4, for example, the upper end portion 66 of the switch housing 10 extends over the top of. the annular air gap 91 This upper end portion 66 has a plurality of small holes formed in it, and these holes are positioned in a circle in alignment with the annular air gap 90. A plurality of switching units 110 extend through the respective holes in the upper end portion 66 of the housing 10 so that the lower portion of each of these switching units extends into the annular air gap 90. The switching units are held in place on the upper end portion 66 of the housing 14 by means of a disk-like plate 112 composed of non-magnetic material, such as aluminum. The plate 112 is secured to the top surface of the top of the housing 10 by a plurality of screws such as the screws 114.

As shown clearly in FIG. 4, the rim 10a of the switch housing 10 extends axially upwardly from the upper end portion 66 to support the cover 34 in spaced relation to the top surface of the upper end portion. The terminals 32, as mentioned, extend through the rim 10a and these terminals are connected to respective ones of the switching units 110. When it is desired to stack a second switching assembly on top of the assembly of FIG. 4, it is merely necessary to remove the cover 34, and to clamp the second assembly in place, with its rotatable shaft 72 coupled to the portion 76 of the shaft 72 of the illustrated assembly.

It is clear that when the shaft 72 of the assembly illustrated, for example, in FIG. 4, is rotated by the motor shaft 60, the rotor assembly is rotated causing the switching unit 110 to be swept by the magnetic flux in the air gap 90. Each time one of these switching units is swept by a variation in that flux due to the tongue and groove elements 100, 1%, or M32, 106, -a magnetic armature in that switching unit is operated to close a pair of switching contacts, and the armature is subsequently operated to open these switching contacts.

The switching unit 110 is shown in detail in FIG. 7. This unit includes a movable contact 120 and a fixed contact 122. These contacts may be composed, for example, of gold alloy. The schematic fragmentary diagram of FIGS. 8A and 8B show one of the switching units 110 being swept by the magnetic flux in the annular air gap 90 as the rotor of the unit is rotated. As shown in FIG. 8A, for example, as the rotor rotates in a counterclockwise direction, the variations in the flux produced by the tongue 1110 and the groove 104- approach the switching unit 110. As a switching unit moves into this area, and as shown in FIG. 8B, the movable contact 120 is drawn against the fixed contact 122. This is due to the fact that the tongue portion 10% brings the ring portion 88 of the pole piece 78 into closer proximity to the magnetic armature of the switching unit than the pole piece 84. When the continued movement of the pole pieces '84 and 78 brings the particular switching unit out of the area between the tongue 1% and the groove 104, the pole piece 84 is again closer to the armature than the ring portion 88 of the pole piece 78, and the armature is moved to draw the movable contact out of engagement with the fixed contact 122.

Therefore, each time the tongue 100 and the groove 104 or the tongue 102 and the groove 1% are swept past a switching unit 110, the movable contact 120 is first drawn into engagement with the fixed contact 122, and the movable contact subsequently is drawn out of engagement with the fixed contact. The action of each switching unit is therefore positive, with the contacts being normally held out of engagement by the flux in the annular air gap and, in the illustrated embodiment, with the contacts being moved into engagement by the variations in the flux twice for each revolution of the rotor of the switching assembly.

The switching unit .110 shown in FIG. 7 includes an upper tubular casing 126 and a lower tubular casing 128. These casings are shown as being annular but they may also be elliptical with the major axis of the ellipse extending in the radial direction between the

pole pieces

78 and 84 in FIGURE 4. By providing the

casings

126 and 128 with an elliptical shape, the pivotal swings of the armature within the casings may be enhanced, as will become apparent subsequently. The casings may also have any other suitable configuration.

The

tubular casings

126 and 128 may be composed of brass, for example, or the casing 126 may even be composed of a magnetic material to act as a magnetic shield for the components of the switching unit. This shield serves to prevent noise pulses from being induced magnetically into the inner active components of the switch ing unit, and it precludes any tendency for such pulses to find their way into the electrical circuitry controlled by such components.

As shown in FIG. 7, the upper tubular casing 126 of the switching unit has a larger diameter than the lower casing 128. The lower casing is mounted coaxially with the upper casing and is fitted into the upper casing, as illustrated. The lower casing is welded or soldered to the lower end of the upper casing, as at 129. A peripheral notch 130 is formed in the upper casing, and this notch engages the plate 112 of FIG. 4 which serves to hold the switching unit in place. The upper casing 126 may have an outer diameter of, for example, .1845 inch.

The lower end of the lower tubular casing 128 of the switching unit is crimped as at 132, and this lower tubular casing is at least partially filled with a damping, insulating fluid, such as a light electrical grade oil.

The switching unit includes a magnetic armature 124, which is preferably of cylindrical shape and which is adapted to be fitted into the lower tubular casing 128. The armature 124 is composed of any suitable magnetic material, and the outer diameter of the armature is less than the inner diameter of the lower tubular casing. An insulating collar 134 is mounted on the lower end of the magnetic armature 124 for pivotal movement with the armature. This insulating collar has an outer diameter which is slightly greater than that of the armature and less than the inner diameter of the lower tubular casing 128.

The oil in the lower tubular casing 128 forms a cushion for the magnetic armature 124, and a film of oil forms between the insulating collar 134 and the inner surface of the tubular casing 128. This film of oil forms a dynamic pivot for the magnetic armature 124 and the collar 134 relative to the casing at the lower end of the tubular casing 128. This dynamic pivotal action occurs about the collar 134 as a fulcrum.

The movable contact 120 has a cup-shaped configuration, and it has a cylindrical end portion 136 of reduced diameter which is inserted in press-fit into the free end of the magnetic armature 124. The cup-shaped movable contact 120 is therefore supported at the end of the magnetic armature 124 in coaxial relation with the magnetic armature and in substantial coaxial relation with the longitudinal axis of the switching unit. In this way, the movable contact 120 is pivotable with the armature.

A tubular insulating member 138 is supported within the upper tubular casing 130. The upper end of the tubular insulating member 138 is open, and the lower end of this member is closed. A pair of apertures are formed in the closed lower end of the tubular insulating member to receive the fixed contact 122 and also to receive a pilot tube 140. The pilot tube 140 is fixedly supported by the insulating member 138 on the longitudinal axis of the switching unit, and the lower end of the pilot tube projects from the insulating member into the mouth of the cup-shaped movable contact 120, in a loose fit with that contact. The pilot tube limits the pivotal movement of the armature 124 and the resulting arcuate movement of the movable contact 120. The pilot tube, therefore, serves to prevent the armature 124 from contacting the side of the lower tubular casing 128. The pilot tube 140 also serves as a back stop for the movable contact 120. The pilot tube is held essentially on the longitudinal axis of the switching unit, as noted, and it is so held in substantial coaxial relationship with the armature 124 and with the movable contact 120.

A connection to the movable contact 120 is made by means of a wire 142 which extends downwardly through the center of the pilot tube and into the mouth of the cup-shaped movable contact 120 in push-fit engagement with the movable contact 4120. A saw-cut is formed at the end of the cylindrical portion 136 of the movable contact to receive the end of the Wire 142 so as to provide a rigid connection between the wire and the movable contact. The wire 142 is relatively thin and flexible so that it can adjust its position in accordance with the pivotal movements of the armature 124. This adjustment in position is such that the wire 142 can flex while the pilot tube 140 remains stationary because of the relatively great inertia of the pilot tube in comparison to the wire.

The pilot tube may be composed of a gold-silver alloy or other nonmagnetic material. The inner diameter of the pilot tube may, for example, be of the order of /1000 of an inch. The inner diameter of the insulating member 138, on the other hand, is of the order of .111 H101], and the inner diameter of the upper tubular casing 126 in the vicinity of the insulating member 138 is of the order of .157 inch.

The fixed contact 122 has a rod-like configuration, and, as mentioned, it extends through one of the apertures in the lower end of the insulating member 138. The insulating member supports the fixed contact 122 in essentitally parallel relation with the pilot tube 140 and spaced from the pilot tube. Therefore, the fixed contact 122 is supported essentially parallel to the longitudinal axis of the switching unit and spaced from that axis. A connecting wire 146 extends through the upper end of the upper tubular portion 126 and is connected to the fixed contact 122. The lower end 122a of the fixed contact 122 is inclined to the longitudinal axis of the switching unit. This enables the axial position of the movable contact 120 in the switching unit to determine the spacing between the movable contact and the fixed contact.

The axial position of the movable contact 120 may be conveniently established during the fabrication of the unit by pulling or pushing the movable contact by means of the wire 142. This movement of the wire 142 causes the entire armature and movable contact assembly to move upwardly and downwardly in the lower tubular casing 10 128 of the switching unit. When the desired positioning of the armature and movable contact has been established, the pilot tube 140 may be crimped against the wire 142 as at 148. The pilot tube then serves to hold the movable contact at a selected axial position.

The clearance between the lower end of the pilot tube 140 and the inner surface of the cup-like movable contact may be of the order of two-thousandths of an inch. This clearance is made sufiicient to permit the movable contact to pivot with the armature 124 and to close against the inclined portion 122a of the fixed contact 122. The movable contact 120 is adapted to engage the fixed contact 122 before engaging the pilot tube since it is disposed in closer relationship to the fixed contact than to the pilot tube.

It will be observed that the magnetic armature 124 and all the electrical components are insulated from the lower casing 128 and upper casing 126 of the switching unit. As the magnetic flux in the rotating annular air gap 90 is swept past the switching unit of Fig. 7, the magnetic armature 124 is periodically pivoted in the described manner. The pivoting of this armature is limited by the engagement of the pilot tube 140 with the inner surface of the movable contact 120. The limiting of this movement by the pilot tube is such that neither the armature 124 nor the movable contact 120 ever touches the wall of the lower tubular casing 128.

The fact that the electrical connections through the switching unit do not include the tubular casings enables the casings to function as shields, and any noise pulses induced on these casings by the magnetic fiux in the rotating annular air gap 90 do not appear in the electric circuit connected to the switching unit. The switching unit is also advantageous in that the electrical switching components are all supported in the upper tubular casing 126. Therefore, none of these components is disposed in the annular air gap 90. This causes these components to be even less susceptible to the induction of electrical noise signals due to the magnetic flux, in the air gap.

The axial adjustment of the movable contact of the switch which, as described above, may be made during fabrication and enables the spacing between the movable and fixed contacts to be precisely established in a relatively simple manner for each switching unit. The natural mechanical resonant frequency of the described unit is above 10 kilocycles. This high natural resonant frequency is such that there is little tendency for the contacts of the switch to bounce during any normal operational speed. Also, the orientation of the armature 124 Within the casing 128 is not critical, and up to plus or minus 30 degrees rotation has been found to produce no noticeable difference in the operation of the switch.

A constructed embodiment of the switching unit as shown in Fig. 7 exhibited a resistance of 1 10 megohms when the switch was open and a resistance of of an ohm when the switch was closed. The gap between the contacts Was established at $4 of an inch, and the response time was of the order of microseconds. It should be pointed out that this precise gap adjustment in the switch was made possible in the presently constructed embodiment by the use of the inclined end 122a of the fixed contact 122; and by the axial adjustment of the fixed contact, made during fabrication of the armature in the described manner.

The switch construction shown in Fig. 9 is similar in some respects to the construction of Fig. 7, and similar elements have been represented by the same numerals. The switch of Fig. 9, however, is constructed to provide a single-pole double-throw action which is desirable for many applications to which assemblies constructed in accordance with the present invention may be placed.

In the assembly of Fig. 9, three fixed

contacts

122, 122' and 122" are provided. These fixed contacts all have inclined lower ends designated respectively as 122a,,122'a and 122"a. The inclined lower ends of the three fixed contacts surround the movable contact 150 and effective- 1y cage the movable contact; so that it, and the armature 124, are prevented, as before, from touching the side of the conductive switch casing. In the latter embodiment, the pilot tube 148 does not extend into the movable contact 120, but is cut off (as illustrated) just below the bottom of the tubular insulating member 138.

A connection 146 is made to the fixed contact 122, as was the case in the embodiment of Fig. 7. A similar connection 146 is made to the fixed contact 122'. No con nection is made to the fixed contact 12 and the contact 122 serves merely as a guide for the movable contact 120 and assists in preventing the movable contact and the armature 124- from touching the sides of the conductive switch casing.

The armature 124 is supported on a cushion of oil which fills the lower tubular portion 128 of the switching unit of Fig. 9 and which extends up into the actual switching cavity of the upper portion 126 to the bottom of the insulating member 138.

A metal bushing 134 is used in the embodiment of Fig. 9 pivotally to support the armature 124 on its cushion of oil. This metal bushing has an outer diameter which is slightly less than the inner diameter of the portion 128 of the switch, and it is affixed to the bottom of the armature 124 by means of an insulating cement. The bushing 13- is therefore insulated from the armature 124, and this bushing provides the desired pivotal support for the armature.

The embodiment of FIG. 9 uses a cat whisker 149 which extends down the center of the pilot tube 148 and into the saw-cut at the bottom portion 136 of the movable contact 120. The movable contact and its armature are axially positioned in the switching unit during the fabrication process by moving the fine wire or cat whisker 149 up and down in the pilot tube. When the desired axial position of the movable contact 120 is reached to provide the proper gaps with respect to the slanted ends 122a and 122a of the respective fixed contacts, the top of the pilot tube 14$ is crimped against the cat whisker 149 to hold the armature and movable contact assembly in place in its oil cushion. The contact wire 142 in the latter embodiment is soldered to the top of the pilot tube.

The unit of FIG. 9 operates in a manner similar to the unit of FIG. 7 when it is positioned in the switching assembly of the invention. Under the influence of the rotating magnetic field, the armature 124 is moved from one of the fixed

contacts

122, 122 to the other to perform a single-pole double-throw switching action.

One application for the unit of FIG. 9 is shown in FIG. 10. FIG. 10 is a fragmentary circuit diagram of a floating capacitor measuring arrangement. It is usual in circuits of this type for a capacitor 200 to have its terminals connected to the respective armatures of a pair of single-pole, double-throw switches, such as the

switches

202 and 204. A unit providing a voltage to be measured, such as a strain gauge 206 has its terminals connected to a first fixed contact of the switch 202 and to a first fixed contact of the switch 204. An amplifier 208 has its input terminals connected to the second fixed con tact of the switch 202 and to the second fixed contact of the switch 204.

The object of the circuit of FIG. 10 is to measure the voltage developed across the gauge 206. When it is attempted to measure this voltage directly, noise voltages picked up by the leads from the gauge cause errors in measurement. For that reason, the capacitor 200 is first connected across the gauge so that it assumes a charge equivalent to the voltage across the gauge, Then, the condenser is switched to the input of the amplifier 208 so that the output of the amplifier provides an accurate measurement of the voltage across the gauge 206, without the introduction of error-producing noise voltages.

It is clear that the switching unit of FIG. 9 when used in the switching assembly described above is 'ideally' suited for performing the switching function in the circuit of FIG. 10. Adjacent pairs of the switching units of FIG. 9 in the switching assembly can have their first fixed contacts connected to the gauge 206, their armaturcs connected to the capacitor 200, and the second fixed contacts connected to the amplifier 208. Then, as the assembly is driven, a rapid switching of the capacitor 200 between the gauge 206 and the amplifier 208 can be effectuated for accurate results. It is apparent, that a plurality of pairs of switching units can be connected into a single amplifier, such as the amplifier 208, for a successive sampling of many gauges such as the gauge 206.

A simplified transducer for reading the inscriptions 77 on the peripheral surface of the magnetic rotor 80 is shown in FIG. 11. threaded stud 210 which may conveniently be threaded through the switch housing into close proximity with the peripheral surface of t e rotor of the assembly, but spaced slightly from that surface. A simple coil 220 is wound around the stud 210, and this coil is connected to a pair of output terminals 222. It has been found that there is sufficient fringing flux from the pole piece 84 to flow through the stud 210 back to the pole piece 83. As the inscriptions 79 are swept past the face of the stud 210, the variations in the reluctance of the path of this fringing flux causes a variation in the flux and a resulting variation in the current linking the winding 220 with a cor responding variation in the output signal across the terminals 222.

The invention provides, therefore, an improved magnetically operated switching assembly which includes a plurality of switching units constructed in the manner described so as to be not susceptible to induced noise pulses from the switch-actuating magnetic flux. The assembly of the invention is constructed to provide singlepole single-throw switching action, or to provide singlepole double-throw switching action.

The assembly is advantageous in that it lends itself to a convenient fabrication process whereby a precise adjustment of the switching contacts is possible for optimum operation of the switching units and assembly.

I claim:

1. A magnetically controlled switching assembly including: means including first and second walls spaced to define a continuous air gap between the walls and provided with contours in at least one Wall to define a displacement in said air gap in the direction between the walls, magnetic means associated with the first-named means for producing in the air gap a magnetic flux having uniform characteristics at successive positions in the air gap and exhibiting variations in characteristics at the position of displacement and in accordance with such displacement, a housing for the switching assembly and having a support portion disposed in spaced relationship to the air gap, and at least one switching unit having a casing and having first and second switch contacts electrically and magnetically isolated from the casing and movable relative to each other and having an armature coupled to a particular one of the switch contacts and in spaced relationship to the other contact and responsive to the variations in the magnetic flux to produce a relative movement of the particular contact into engagement with the other contact, the switching unit being supported by the support portion of the housing and extending into the air gap with the armature disposed in the air gap to respond to the variations in the magnetic flux in the air gap, and means for imparting relative motion between the first-named means and the switching unit to produce periodic actuations of the switching unit.

2. A magnetically controlled switching assembly including: rotatable means including first and second walls spaced to define an annular air gap between the walls and having contours to define a displacement in said air gap This transducer takes the form of a in at least one position along said walls, means associated with the rotatable means for producing in the annular air gap a magnetic flux exhibiting variations in the position of displacement in said air gap, a stationary housing for the switching assembly and having a first portion extending in spaced relationship to the annular air gap, at least one stationary switching unit supported in the first portion of the stationary housing and extending into the annular air gap, the switching unit including an armature formed at least in part of magnetic material and disposed in the annular air gap and responsive to the variations in the mgnetic flux in the air gap to control the actuation of the switching unit, and means coupled to the rotatable means for rotating the rotatable means to produce relative motion between the magnetic fiux in the air gap and the switching unit to bring the armature of the switching unit periodically under the influence of the variations in the magnetic flux.

3. A magnetically controlled switching assembly including: a disk-shaped axially magnetized permanent magnet supported for rotation about its axis, a first pole piece for the permanent magnet including a disk-shaped portion contiguous to one face of the permanent magnet for rotation therewith and in coaxial relation with the permanent magnet and including a cylindrical portion secured to the periphery of the disk-shaped portion and surrounding the permanent magnet in spaced relation from the peripheral surface of the permanent magnet, the peripheral surface of the pole-piece having a plurality of angularly spaced inscriptions formed thereon, a second pole piece for the permanent magnet and including a diskshaped portion contiguous to the other face of the permanent magnet for rotation therewith in coaxial relation with the permanent magnet and defining an annular air gap with the first pole piece, the permanent magnet serving to produce a magnetic flux in the annular air gap and at least one of the first and second pole pieces being shaped to cause the magnetic flux to exhibit variations in at least one position in the air gap in a direction transverse to the direction of rotation of the first and second pole pieces, a stationary housing for the switching assembly and surrounding the cylindrical portion of the first pole piece and having a first portion extending in spaced relationship to the annular air gap, at least one transducer means supported by the stationary housing in magnetically coupled relationship with the inscriptions on the peripheral surface of the annular portion of the first pole piece as the magnet is rotated, at least one stationary switching unit supported by the top portion of the stationary housing and extending into the annular air gap, the switching unit including an armature formed at least in part of magnetic material and responsive to the variations in the magnetic flux in the air gap to control the actuation of the switching unit and including a stationary contact and a contact movable with the armature into engagement with the first contact in at least one position of the armature, and means coupled to the permanent magnet and the first and second pole pieces for rotating the permanent magnet and the first and second pole pieces to produce relative motion between the magnetic flux in the air gap and the switching unit to bring the armature of the switching unit periodically under the influence of the variations in the magnetic flux.

4. A magnetically controlled switching assembly including: means including first and second walls spaced to define a continuous air gap between the walls and having contours to define a displacement in the air gap in at least one position along the walls and having prop erties to produce in the air gap a field exhibiting variations at the position of displacement, at least one switching unit having a casing with at least a first portion formed from electrically conductive material and having the electrically conducting portion of the casing extending into the air gap, an armature pivotally disposed within said electrically conducting portion of the casing in electrically insulated relation therewith, said armature being composed at least in part of magnetic material, and means for producing relative motion between the magnetic flux in the air gap and the switching unit to bring the armature periodically under the control of the variations in the magnetic flux.

5. A magnetically controlled switching assembly including: means including first and second walls spaced to define a continuous air gap between the walls and having contours in at least one wall to define a displacement in the air gap in at least one position along the walls and in a direction transverse to the walls and having properties to produce in the air gap magnetic flux extending between the walls to obtain variations in the magnetic flux at the position of displacement and in accordance with such displacement, at least one switching unit having a casing with an electrically conductive portion extending into the air gap, an armature disposed within said conductive portion of the casing in loose relationship to the casing for pivotable movement relative to the casing and formed at least in part of magnetic material, an insulating collar formed at one end of the armature and having transverse dimensions greater than the transverse dimensions of the armature, a damping fluid filling at least partially said conductive portion of the casing to form a cushion for the armature and to form a film between the collar and the inner surface of the conductive portion to provide a dynamic pivot for the armature, and means for producing relative motion between the magnetic flux in the air gap and the switching unit to bring the armature periodically under the control of the variations in the magnetic flux for a pivotal movement of the armature in accordance with the variations in the magnetic flux.

6. The switching assembly set forth in claim 5 in which the switching unit is provided with electrical contacts and with electrical wires coupled electrically to the contacts and ext-ending from the contacts to a position external to the switching unit and in which the contacts for the switching unit and the electrical wires extending from the contacts are disposed out of the magnetic field produced between the first and second walls to prevent any changes in the magnetic field as a result of the closure of the contacts.

7. A magnetically controlled switching assembly including: a switching unit having a casing provided with a particular portion having electrically conductive properties, the casing being constructed to hold a lubricating liquid in the particular portion of the casing in a particular disposition of the casing, an armature disposed in insulating relation to the casing in the particular portion of the casing and formed at least in part of magnetic material and having an outer diameter less than the inner diameter of the particular portion of the casing for movement of the armature in the casing and having an insulating collar disposed on the armature, the collar having outer dimensions less than the inner dimensions of the particular portion of the casing and greater than the outer dimensions of the armature, there being the lubricating liquid in the particular portion of the casing for providing a cushion for the armature and for providing a film between the collar and the inner surface of the particular portion to produce a dynamic pivot for the armature about the collar as a fulcrum.

8. A magnetically controlled switching assembly including: a switching unit having a casing formed from first and second portions and constructed to retain a lubricating fluid in the first portion, the second portion of the casing having greater dimensions than the first portion of the casing, at least the first portion of the casing being made from an electrically conductive material, an armature disposed in the first portion of the casing in insulating relationship with the casing and formed at least in part of magnetic material and provided with a restricted portion near the end removed from the second portion of the casing, an insulating collar disposed on the restricted portion of the armature and having outer dimensions less than the inner dimensions of the first portion of the casing, there being lubricating fluid in the lower portion of the casing for forming a cushion for the armature and for forming a film between the collar and the armature to provide a dynamic pivot for the armature about the collar as a fulcrum, a cup-shaped movable contact afiixed to the end of the armature near the second portion of the casing, an elongated pilot tube, insulating means coupled to the pilot tube for supporting the pilot tube in the second portion of the switching unit with a first end of the pilot tube extending into the mouth of the cup-shaped movable contact to limit the pivotal movement of the armature and of the movable contact, a connecting wire extending through the pilot tube and into electrical connection with the movable contact, and a fixed contact supported by the insulating means in the second portion of the casing and disposed relative to the movable contact to be engaged by the movable contact upon a pivotal movement of the armature.

9. A magnetically controlled switching assembly including, a switching unit having a conductive casing, a magnetic armature pivotably supported in the conductive casing in insulating relation therewith, a cup-shaped movable electric contact afiixed to the free end of the armature, tubular means supported in the switching unit in insulating relation with the conductive casing and extending in loose fit into the mouth of the movable contact to limit the movement of the movable contact and thereby prevent the magnetic armature from touching the conductive casing, a connecting wire extending through said tubular means and afiixed to the movable contact in electrical connection therewith, and a second contact supported in the switching unit in spaced relationship to the movable contact to engage the movable contact upon a pivotal movement of the armature.

10. A magnetically controlled switching assembly in cluding movable means including first and second walls spaced from each other in a direction transverse to the plane of movement to define a continuous air gap and provided with contours to define a displacement in the air gap at a particular position and in the transverse direc tion, means including the first and second walls for producing a magnetic flux across the air gap in accordance with the positioning of the air gap in the transverse direction to obtain variations in the magnetic flux at the position of displacement of the air gap and in accordance with such displacement, a stationary housing for the switching assembly and having a first portion extending in spaced relationship to the annular air gap, at least one stationary switching unit supported in the first portion of the stationary housing and extending into the annular air gap, the switching unit being provided with a conductive casing, a magnetic armature being pivotally supported in the conductive casing in insulating relationship with the casing, a movable electrical contact fixed to the free end of the armature for pivotal movement with the armature, and means supported in the switching unit in insulating relationship with the conductive casing to limit the pivotal movement of the pivotal contact and thereby prevent the magnetic armature from touching the conductive casing.

11. A magnetically controlled switching assembly including, a switching unit having a conductive casing, a magnetic armature pivotably supported in the conductive casing in insulating relationship therewith, a movable electric contact afiixed to the free end of the armature, tubular means supported in the switching unit in insulating relationship with the conductive casing, a connecting wire extending through the tubular means and afiixed to the movable contact in electric connection therewith, and a plurality of fixed contacts supported in the switching unit in spaced relationship with the movable contact and surrounding the movable contact to be selectively engaged by the movable contact upon pivotal movement of the armature, said fixed contacts limiting the pivotal movement of the movable contact and thereby preventing the movable contact and the magnetic armature from. engaging the conductive casing.

12. A magnetically controlled switching assembly cluding: an annular permanent magnet supported for rotation about its longitudinal axis, a first pole piece for the permanent magnet and disposed in contiguous relationship to one face of the permanent magnet for rotation therewith and including an annular portion surrounding the permanent magnet in spaced relation from its peripheral surface, a second pole piece for the permanent magnet and disposed in contiguous relationship to the other face of the permanent magnet for rotation therewith and defining a rotatable annular air gap with the first pole piece, the outer peripheral surface of the annular portion of the first pole piece having a plurality of angularly spaced axially extending inscriptions formed thereon, the permanent magnet serving to produce a magnetic flux in the annular air gap, and at least one transducer means mounted on the housing relative to the inscriptions on the peripheral surface of the first pole piece for sensing the inscriptions to produce signals as the permanent magnet and the first and second pole pieces are rotated with respect to the stationary housing.

13. A magnetically controlled switching assembly including means including first and second Walls spaced to define a continuous air gap between the Walls and having contours to define a displacement in the air gap in at least one position along the walls and having properties of producing in the air gap a field exhibiting variations at the position of displacement, means coupled to the first and second walls for producing a magnetic field in the air gap in accordance with the disposition of the air gap at successive positions, there being inscriptions in a particular one of the first and second walls at spaced positions along the particular wall, switching means disposed in the air gap and responsive to the variations in the magnetic field to be actuated from one operating condition to another, transducing means disposed relative to the particular one of the first and second Walls to sense the magnetic changes resulting from inscriptions in the particular wall, and means for producing relative motion between the walls and the switching means to bring the switching means periodically under the influence of the variations in the magnetic field and to bring the transducing means periodically under the influence of the inscription.

14. The combination set forth in claim 13 in which means are responsive to the signals produced by the transducing means and to the variations in the magnetic field in the air gap to produce signals only upon the simultaneous occurrence of the variations in the magnetic field in the air gap and of the signals produced by the transducing means.

15. A magnetically controlled switching assembly, including, rotatable means including first and second walls spaced from each other in a direction transverse to the plane of rotation to define an air gap extending in the di rection of rotation and provided with contours to define a displacement in the air gap at a particular position in the transverse direction, means including the first and second walls for producing a magnetic flux across the air gap in accordance with the positioning of the air gap in the transverse direction to obtain variations in the magnetic flux at the position of displacement of the air gap in the transverse direction and in accordance with such displacement, there being inscriptions disposed in a particular one of the first and second walls as spaced positions in the annular direction, transducing means disposed relative to the inscriptions in the particular one of the first and second walls to detect changes in the magnetic field resulting from such inscriptions, at least one stationary switching unit disposed in the annular air gap and including an armature constructed at least in part of magnetic material and responsive to the variations in the magnetic flux in the air gap to obtain a controlled operation of the switching unit in accordance with such vari- 17 ations, and means for rotating the rotatable means to produce relative motion between the magnetic flux and the switching unit to bring the armature periodically under the influence of the variations in the magnetic flux in the air gap and to bring the transducer periodically under the influence of the inscription.

References Cited in the file of this patent UNITED STATES PATENTS 18 Vale et al. Oct. 18, 1949 Hastings Apr. 3, 1951 Price July 15, 1958 Ormond Feb. 3, 1959 Peek Aug. 4, 1959 Robinson et a1. Nov. 10, 1959 Scata Jan. 12, 1960 Kennedy Jan. 26, 1960 FOREIGN PATENTS Germany Mar. 27, 1936 France July 13, 1955