US2740860A - Rotary magnetic multiple switch - Google Patents

Description

April 3, 1956 G. c. WALSH ROTARY MAGNETIC MULTIPLE SWITCH 5 Sheets-Sheet 1 Filed Oct. 8, 1954 III I III II :HIHIII an m' FIGIEL FlGIE INVENTOR.

GEORGE C. WALSH AGENT April 3, 1956 Filed Oct. 8, 1954 G. C. WALSH Sheets-Sheet 2 S 3 oTL LEvEL 0m LEvEL 43 44 E Z 45 i a. 26 40 lo- 2 6 P I 4 31 40 I 42 41 E g 49 24 42 49/ 5E 48 4s 48 g5 52 4e 30 5 E L E 5| \5 16 61% b, y 27 28 f E [4' 2 Z I7 55 FIG 11 INVENTOR.

GEORGE C. WALSH aaqiim H, dawn,

AGENT April 3, 1956 G. c. WALSH ROTARY MAGNETIC MULTIPLE SWITCH 5 Sheets-Sheet Filed Oct. 8, 1954 Illllllllllll FIGI INVENTOR.

GEORGE C. WALSH AGENT April 3, 1956 c, WALSH 2,740,860

ROTARY MAGNETIC MULTIPLE SWITCH Filed 001.. 8, 1954 5 Sheets-Sheet 4 (muaanaQb INVENTOR. GEORGE C. WALSH A ril 3, 1956 G. C. WALSH ROTARY MAGNETIC MULTIPLE SWITCH Filed Oct. 8, 1954 MAGNET APPLIED TO CLOSE IE SINGLY IN SUOCESSION (G-CLOSED) HI H2 o MEASURING INSTRUMENT 5 Sheets-Sheet 5 FIG. 1X1]:

(A- CLOSED) INVENTOR. GEORGE C. WALSH JZUZ CQ AGENT United tates Patent ROTARY MAGNETIC MULTIPLE SWITCH George C. Walsh, Foxboro, Mass, assignor to The Foxboro Company, Foxboro, Mass, a corporation of Massachusetts Application October 8, 1954, Serial No. 461,147

1 Claim. (Cl. 2130-87) This invention relates to electrical switches and has particular reference to multiple switch units which use rotary magnets to separately operate the several portions of the switch units.

A mechanically operated prior art multiple switch unit is disclosed in the Cobbett Patent 2,184,611, issued December 26, 1939. This prior art structure is operated by a rotary cam member and is used for connecting in serial manner a plurality of electrical circuits to a common circuit.

The present invention provides a generally improved rotary magnet multiple switch which is specifically an improvement with respect to the Cobbett switch mentioned above. The switch of the present invention, like that of the Cobbett patent above, is provided for connecting in serial manner a plurality of electrical circuits to a common circuit. As an illustrative example of its use, the switch of this invention is a compact, efficient unit, designed for use with multi-record recorders, such as that disclosed in the Bowditch Patent 2,674,513, issued April 6, 1954. The switch of the present invention may also be used, for example, as an improved stepping switch for segmental recording, or for scanning devices.

The structure of the present invention is operable with a minimum of friction between the electrical contacts of the switch, with no mechanical operating connection between the switches and the switch operating magnet and consequently with a minimum of torque. The switches may be provided normally closed, or as detailed herein, normally open. As a further feature the switch contacts of the unit of this invention may be operated in a bath of electrically non-conductive oil or in an immediate atmosphere of inert gas. These arrangements lengthen the life of the switch contacts and provide a safety factor when the switch is used in explosive or dirty atmospheres. With these arrangements there is no danger of igniting such atmospheres by arcing at the contacts incident to the making and breaking of the circuits embodying the contacts. Further, the oil bath especially prevents contact oxidation and acts as a contact lubricant.

It is therefore an object of this invention to provide a new and improved rotary magnetic multiple switch.

Other objects and advantages of this invention will be in part apparent and in part pointed out hereinafter, and in the accompanying drawings, wherein:

Figure I is an elevation of a switch unit embodying this invention;

Figlre II is a bottom view of the structure of Figure 1;

Figure III is a top view of the structure of Figure I;

Figure 1V is a view of the structure of Figure l in vertical central section, showing, for the sake of clarity, only two of the switches;

Figure V is an elevation of the switch mounting inner housing as stripped and removed from the structure of Figure I;

Figure V1 is a vertical central section of the structure of Figure V;

2,740,860 Patented Apr. 3, 1956 ice Figure VII is a perspective view of the magnet unit and gear as removed from the structure of Figure I;

Figure VIII is an exploded view, in perspective, of the magnet unit and gear of Figure VII;

Figure IX is a perspective view of a double switch structure for use in an embodiment of this invention;

Figure X is an exploded view, in perspective, of the double switch of the structure of Figure IX;

Figure XI is a switch circuit according to the present invention and embodying the double switch structures according to Figures IX and X; and

Figure XII is a switch circuit according to the present invention and embodying single switch structures as shown in Figure IV.

With reference to Figures I-III, the switch unit according to the illustrated embodiment of this invention is a generally cylindrical body 10 which is provided with a support base 11, raised on a pair of diametrically opposite feet 12, with openings 13 therethrough to receive mounting bolts (not shown) as a means of securing the switch unit to a suitable support (also not shown). The main body of the support base 11 is a base plate 14 generally in the shape of a star with four 90 degree spaced blunt legs 14'. The feet 12 are extensions of the outer ends of two opposite legs 14', and four uprights 15 extend up from the base plate 14, one at the outer end of each of the legs 14'. Thus the support base 11 stands the switch body 10 away from its mounting (not shown) and provides a protected opening 16 above the base plate 14 and below the switch body it). A gear 17 is located in the opening 16 with a pinion 18 meshed therewith and a pinion shaft 19 is provided for driving the pinion 18 which in turn drives the gear 17. As will be detailed hereinafter, rotation of the gear 17 results in rotation of a magnet unit as illustrated in Figure VII. This magnet unit is secured, as in Figures 1, II, and IV, to the base plate 14 by means of a threaded shaft 20, extending through the center of the base plate 14 concentrically with the longitudinal axis of the whole unit and secured by a nut 21 on the under side of the base plate 14. The base plate uprights 15 support a lower flange 22 of an inner housing 23 (Figure V). An outer, cylindrical housing 24 is mounted on the flange 22, and switch connection wires 25 extend upward through the top of the switch unit, in sealed and insulated relation therewith.

Figure TV shows the inner structure of the unit of Figure I. In this showing, for the sake of clarity, only two single switches 26 are shown instead of the six that may, for example, be used. In many instances, also, it is desirable to use double switches such as are illustrated in Figures IX and X, and, for example, six of such double switches may be used.

Thus Figure IV shows the support base 14, the inner housing 23, the switches 26, the outer housing 24, and a magnet assembly 27.

Referring to Figures lV-Vi, the inner housing 23 comprises a central cylindrical inverted cup 23, with the lower end thereof provided with the flange 22 extending radially outward therefrom and having a downwardly facing nular channel 29 therein for receiving the base plate uprights 15, and an upwardly facing annular channel 30 for receiving and sealing the bottom edge of the outer housing 24. The inner housing 23 has a transverse dividing wall 31 located about midway vertically thereof, as the bottom of inverted cup 23. A second and upright cylindrical cup member 32, with a somewhat greater diameter than that of the inverted cup 28, is mounted on and sealed to the top of the dividing wall 31 in continuance of the structure of the'inner housing 23. The side wall of the second cup member 32 is shown as cut out to form a circular series of equally spaced switch supports 33 which have relatively wide portions for mounting the switches,

aradseo and relatively narrow portions for providing sufficient space to allow the switch connection wires to be taken into the second cup 32, from whence they are passed through a top plate 34 of the inner housing 23. The top plate 34 is secured to the tops of all the switch supports 33, and extends radially outward therefrom to terminate in an upwardly extending annular flange 35 on which the top of the outer housing 24 is mounted and sealed by means of a downwardly facing annular channel 36 (Figure lV), formed by the inturned top edge of the outer housing 24.

As shown in Figure IV, the assembly of the inner and outer housings 32 and 24 provides a closed and sealed chamber 37 which is cylindrical at one end and cylindrically annular at the other (lower) end. in one embodiment of this invention, this sealed chamber may be substantially filled with a body of suitable electrically non-conductive oil as a means of preventing switch contact arcing, with the result that switches immersed in the oil may be safely used in explosive atmospheres and that the switch contacts are longer lived.

The switch assemblies 26 (Figure IV) are mounted on the inner housing uprights 33. Only two switch assemblies and their supporting uprights 333 are shown in Figure IV but the particular structure shown is designed to mount a total of six switch assemblies, in a circle within the closed chamber 37. Each switch assembly includes three flexible arms 4! ill, and 42, with electrical insulation spacers 43 therebetween and a metal mounting bar 44 capping the assembly, and with the whole device held together and secured to its upright 33 by a pair of screws 4-5. The flexible arms to, 4-1, and .12 are in overlying alignment with each other, all extending downward in the sealed chamber 3'7 and parallel with the central, longitudinal axis of the entire switch unit. Flexible arm 40 lies close to the inner wall of the sealed chamber annulus, with a magnetic material strip 46 secured thereto to lie between the flexible arm 4d and the inner wall of the sealed chamber annulus.

As will be seen hereinafter, each magnetic strip 46 bears a purposeful and predetermined dimensional relation to the magnet assembly 27. The flexible arm as, further, is provided with a laterally and outwardly extending pin 417 for engaging the lower end portion of the flexible arm 42. In the open condition of the switches 26, as shown at the right in Figure IV, the normal, at rest position of the flexible arm ill is at an angle laterally and radially away from the inner wall of the sealed chamber annulus. The result of this arrangement is that the flexible arm 42 is held laterally outward with respect to the normal at rest position of the arm 42.

Consequently, when the magnet assembly 27 is applied, by rotation, to a switch in the condition shown at the right in Figure TV, the flexible arm 4 19 is drawn toward the longitudinal axis of the whole switch unit, away from its normal at rest position, and the flexible arm 42 is thus allowed to move, also toward the longitudinal axis of the switch unit and toward its at rest position. As a result, the middle flexible arm il and the outer flexible arm 42 are engaged, through cooperating electrical contacts 43 and d9 thereon. The middle flexible arm ll is shorter than the other arms (4% and 42) so that the pin &7 from the flexible arm 4 d extends past the end of the middle flexible arm 411i to engage the outer flexible arm 42. The flexible arms 41 and 42 are part of the electrical path in the switch and they are provided with electrical leads 4 and 42' to their respective switch connection wires (25). The flexible arm 4% is not part of the electrical circuit through the switch, but is simply the magnetic material carrier which biases the switch to open con dition in the absence of a magnetic field as applied to the magnetic strip 46 by the magnet in the magnet assembly 27.

The Figure IV left hand switch assembly 26 shows the positions of the flexible arms 40, 4-1, and 42, when the magnetic field has been applied to that switch with the result that the switch contacts 4%; and 49 are engaged and the switch is closed. it may be noted here that the switch contacts 48 and 49 are immersed in the body of electrically nonconductive oil.

The magnet assembly 27 is detailed in Figures IV, VII, and VIII. It is mounted on the shaft 20, the upper headed end 26 of which is fixed to the inner housing (23) transverse wall structure formed by the sealed juncture of the wall and the base of the upper cup member 32. A hearing sleeve 50 is mounted on the shaft 26 and is held between the under side of the shaft head 20 and the base plate lid by the nut 21 on the lower end of the shaft 20. Thus the shaft Zil is fixed, and the magnet assembly is mounted on the bearing sleeve St for rotation about the shaft Zil.

The magnet bearing sleeve 50, near its lower end, is provided with an annular outstanding shoulder 51. The magnet proper consists of a bottom pole piece 52, the main body 53 of the magnet, and a top pole piece 54. The pole pieces 52 and 5d are in flat tear drop form, mounted on and extending transversely of the bearing sleeve 54 and each having a tear drop base opening through which the bearing sleeve 50 extends. The pole pieces are arranged in overlying alignment with each other, and the apexes of the tear drop forms extend to adjacency (Figure IV) with the outer face of inner wall of the sealed chamber 3'7, and therefore into adjacency with the magnetic strips 46 on the switches 26 within the sealed chamber.

The magnet main body 53 is in the form of a magnet which is sleeve mounted on the bearing sleeve 54 between the pole pieces 52 and 54. The drive gear 17 is also mounted on the bearing sleeve, so as to abut on the under side of the bearing sleeve shoulder 51. The bottom pole piece rests on the top side of the bearing sleeve shoulder Sit, and the assembly is held together by a pair of screws 55. The magnet sleeve is vertically slotted at one side to accommodate one of the screws 55. The magnet body 53, the pole pieces 52 and 5d and the magnetic material strips 46 are the only members in the effective area of the magnet which are susceptible to magnetic attraction. As shown in Figure IV, the distance between the pole pieces 52 and 54 is approximated by the length of the magnetic material strips d'll on each of the switch assemblies 26. The strips 40 thus extend essentially from pole to pole in the magnet and are sufiiciently close thereto to form an efficient fiux guide for the magnetic field of the magnet. As a result, an efficient switch unit is provided, with a relatively strong magnetic attraction thus provided for the operation of each of the switches.

Figures IX and X show a double switch unit which may be used instead of the single switch unit shown in Figure IV. With this arrangement, the rotary magnet operates two switches at each rotary position, thus providing, for example, a set of twelve switches operable in pairs. Figure X1 is a circuit showing of a set of double switches wherein simultaneous breaks are made in two leads from each of a set of temperature measuring electrical resistance elements G-L. in the showing of Figure XI, the rotary magnet is considered as applied to the double switch G alone so that the switch contact pairs G1 and G2 are both engaged, while the contact pairs of the other double switches H-L are all separated.

Figure XII is a circuit showing of a set of single switches AF like those shown in Figure iV, wherein one lead of each of a set of thermocouple elements AF' may be broken, respectively, by the contacts A-F. In this drawing, the rotary magnet is considered as applied to the single switch A alone so that the switch contact pair thereof is engaged, while the contact pairs of the other Single switches B-F are all separated.

The circuit showings of Figures X1 and XEI are in tended to be merely illustrative of possible wiring connections of rotary magnet switches embodying this invention, for example, as applied to switch structure like that illustrated in Figure IV.

Again referring to Figures iX and X, the double switch assembly comprises two sets of fiexures 56, 57, and 53, 59, comparable to the flexure set 41, 42 of Figure IV, and a third flexure 60, comparable to the flexure 40 of Figure IV. The flexure set 56, 57 has a pair of cooperating contacts 61, 62, and the flexure set 58, 59 has a pair of cooperating contacts 63, 64. The ilexures 56 and 58 are joined at their outer ends by a rigid cross bar 65 by means of rivets 66, and the flexure 60 is provided with an actuating pin 67, comparable to the pin 47 of Figure IV, for engaging the cross bar 65 as a means of simultaneously opening or closing both contact pairs 61, 62 and 63, 64 in the manner and by means of similar flexure bias and mounting arrangements, with respect to the showing in and the description herein of Figure IV.

Again as shown in Figures IX and X, the flexure 68 has a magnetic material strip 68 mounted thereon, and various spacer, insulating and mounting plates are provided vertically between the fiexures, with the whole assembly held together by screws 69. Electrical connection leads 56', 57, 5 and 59 are provided respectively on the flexures 56-59. The only magnetic material within range of the rotary magnet as assembled is the magnetic strip 68.

This invention, therefore, provides a new and useful rotary magnet multiple switch, wherein compact and improved switch structure is provided, and wherein an embodiment provides contacts immersed in oil with resultant features of safety and long contact life.

As many embodiments may be made of the above invention, and as changes may be made in the embodiments set for above, without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative only and not in a limiting sense.

I claim:

For use in multi-measurement instruments wherein a series of different variable conditions are repeatedly measured by a single instrument through the use of an automatic electrical switching unit with a high degree of explosion proof character and which connects in serial manner a plurality of measurement elements to a common circuit in said instrument; a generally cylindrical, compact, essentially fully enclosed, rotary magnetic switch unit wherein a series of electrical double switch assemblies in an oil bath in a single chamber are actuated as a magnet is rotated within said unit, said unit comprising, in combination, a single, completely closed metallic chamber housing having one end in cylindrical form and the other end in cylindrical annular form, with circumferentially spaced switch assembly mounting supports extending through said one end cylinder form in apertured continuance of the inner wall of said cylindrical annular form, a body of electrically non-conductive oil substantially filling said closed chamber, a series of electrical double switch assemblies, mounted in a circle around said annular formation and within said chamber, with one of said switch assemblies mounted on each of said switch assembly mounting supports, each of said switch assemblies being elongated in form and extending lengthwise of the whole switch unit and essentially through both the cylindrical form and the cylindrical annular form of said closed chamber in parallel with the longitudinal axis of the whole switch unit, each of said double switch assemblies comprising a single flexure arm lying adjacent the inner wall of said cylindrical annular form of said closed chamber, a magnetic material armature strip fixed to said single flexure arm and lying between said single flexure arm and the inner wall of said cylindrical annular form of said closed chamber, a switch operating pin on an end of said single flexure arm which lies in said cylindrical annular form of said closed chamber, with said single flexure arm formed and mounted with self spring bias radially outward from the longitudinal axis of the whole switch unit, a first pair of contact arms electrically insulatedly spaced side by side and radially outward with respect to said single flexure arm and the longitudinal axis of the whole switch unit, each of said first pair of contact arms having an electrical contact button radially outwardly facing and located at an end of its respective contact arm which lies in said cylindrical annular form of said closed chamber, with said first pair of contact arms of equal length and shorter than said single flexure arm, whereby said single flexure arm switch operating pin extends radially outward past the said first pair of contact arms, a second pair of flexible contact arms electrically insulatedly spaced side by side and radially outward with respect to said first pair of contact arms, each of said second pair of contact arms having an electrical contact button for circuit closing engagement with a respective one of said first contact arm contact buttons, said second pair of contact arms being essentially of equal length with each other and with said single flexure arm, with an electrical insulation cross-piece joining said second pair of contact arms as an engagement member for said switch operating pin, said second pair of contact arms being formed and mounted with self spring bias radially inward, said bias being normally overcome by the radially outward bias of said single flexure arm, whereby said contact buttons are all normally separated, the mounting of said arms comprising a lamination of arms and separators in the cylindrical form of said closed chamber and on a respective one of said switch mounting supports, with said contact arms having electrical leads therefrom extending individually through the wall of said housing in insulated relation therewith, a second, cylindrical chamber, defined by the cylindrical annular form of said closed chamber, and a magnet assembly with a large portion thereof in said second chamber, said magnet assembly comprising a base with spaced peripheral uprights supporting said closed chamber housing, a fixed center post extending into said second chamber along the longitudinal axis of said whole switching unit, a mounting sleeve rotatably mounted on said center post and having an annular abutment thereon, and a magnet assembly comprising a driving gear on said mounting sleeve against one side of said abutment, a first magnet pole piece on said mounting sleeve against the other side of said abutment, a magnet in the form of a spacer sleeve on said mounting sleeve and with one end against said first pole piece, a second magnet pole piece on said mounting sleeve and against the other end of said magnet, and a pair of bolts extending through said driving gear and said pole pieces to hold said magnet assembly together, said pole pieces being mounted transversely of and ofif center on said mounting sleeve to form extensions of said magnet which extend to adjacency with said cylindrical annular form of said closed chamber and to said magnetic armature strips therein in turn as said magnet is rotated by the operation of said gear.

References Cited in the file of this patent UNITED STATES PATENTS 922,673 Crist May 25, 1909 980,863 Burnham Jan. 3, 1911 1,530,936 Greenwood Mar. 24, 1925 2,310,138 Whittaker Feb. 2, 1943 FOREIGN PATENTS 277,787 Great Britain Sept. 29, 1927 720,957 France Dec. 12, 1931

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