US2902564A - Rotary switch - Google Patents

Description

Sept. 1, 1959 H. G.'FLECK ROTARY swnca Filed Aug. 6, 1956 FIG.I

INVENTOR.

HORST G. FLECK HIS ATTORNEY ite Patented Sept. l, 1953 ROTARY swrrcn Horst G. Fleck, Brookfi'eld, Conn., assiguor, by mesne assignments, to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas Application August 6, 1956-, Serial No. 602,162

3 Claims. (Cl; 200- 104) The present invention relates to rotary switches and, more particularly, to a magnetically operated rotary switch to make and break a plurality of circuits in a continuous predetermined pattern.

On certain operations amake and break of a plurality of circuits at frequent predetermined intervals is required, as, for instance, when checking stations inthe course of a manufacturing process. In the past it has been common to use mechanically operated step switches. However, where the interval for the successive completion of circuits is short, such as about once every second, and the operation is continuous over long periods of time, mechanical switches wear rapidly. Furthermore, mechanical switches have the disadvantage of requiring power: to overcome contact friction. While other rotary magnetic switches are known, many such switches are complicated and costly.

It is therefore an object of this invention to provide a new and improved rotary switch to make and. break a plurality of circuits which issimple, inexpensive and longlived.

It is a further object to provide a new and improved rotary switch having a small power requirement.

It is a still further object to provide a new and improved rotary switch designed to make and break. a plurality of circuits in a continuous predetermined cycle.

These and other objectsare. accomplished in accordance with the present invention by adevice including a rotatable shaft supported by a base and to which is secured a permanent magnet having a pole face directed radially outwardly from the shaft. A plurality of thin elongated spring arms made of a magnetically attractable and elect-rically conductive material are supported at their'lower ends by the base, and the spacing and number of. spring.

arms may be chosen according to the switching pattern desired. The free ends of the spring arms are spaced a relatively short distance from the rotary path of. the pole face of the magnet and flex inwardly from. an unbiased position to a biased position as the magnet rotates and each free end successively comes Within the magnetic field..

An electrical contact which takes the form of an annular ring issupported in fixed relation to the base. The magnet is adjustably mounted and isv focused so that as the shaft is rotated, it successively and sequentially attracts only one of the spring arms to make and break electrical contact with the annular ring.

These and other features of my invention will be apparent from the following. detailed description of a preferred form of my invention taken: in conjunction with the accompanying drawing wherein:

Fig. 1 is a perspective view of the switch of the present invention with portions cut away to show more clearly interior details;

Fig. 2 is an exploded view of the switch showing the various elements; and

Fig. 3' is a top sectional view of a portion of the apparatus ofFig. 1 taken on the midplane of disk 20.

In Fig. 1' of the drawing is shown a rotary switch 10, constructed in accordance with the present invention, mounted on a baseboard 11. Rotary switch 10 comprises, broadly, a firstmounting disk 12 made of insulating material fixed parallel to and in spaced relationship to baseboard 11. Secured to the edge of disk 12 perpendicular to its plane are a plurality of spaced spring arms 13 made of magnetic material, each of which carries at its upper end a movable contact 14. Fastened to the lower end of each spring arm 13 is a conducting strip 15. The free end of each conducting strip 15 serves as a terminal for a lead 16, each of which may be connected to an electrical device. A second insulating disk 17 is fixed parallel to and in spaced relationship to first disk 12 and carries on its upper face a ring 18 of conducting material which serves as a fixed contact and is placed so as tobe opposite movable contacts 14. Shaft 19 carries a support arm or disk 20 at the outer perimeter of which is fixed a permanent magnet means 21 placed so as to be opposite the upper ends of spring arms 13. As magnet means 21 is rotated, each of successive spring arms 13 is selectively attracted inwardly, thereby engaging movable contacts 14 sequentially with ring 18. The circuit is completed by the connection of a lead between the ring and an electrical device or devices.

More particularly, referring to the exploded view of Fig. 2, baseboard 11 has a central aperture 30 to permit passage of shaft 19, which, in the preferred embodiment illustrated, extends all the way through the switch. Baseboard 11, which is made of insulating material, is also provided with three smaller apertures 31 equally spaced from aperture 30 and from each other. First disk 12 is likewise made of insulating material and has three apertures 32 aligned with apertures 31 and also has a central aperture 33 to permit passage of shaft 19. Each of screws 34 passes through an aperture 32, then through a bushing 35 which serves to space first disk 12 from baseboard 11, and thence is screwed into an aperture 31. The first disk 12 is thus fixed parallel to and spaced from baseboard 11.

Secured to the edge of disk 12 by screws 36 or the like are the plurality of reed-like arms 13 made of some resilient conductive magnetic material such as strip spring steel. Spring arms 13 are preferably mounted parallel to shaft 19- and are equally spaced. A movable contact 14 of any conventional form is carried by the upper end of each spring arm 13.

Each spring arm has a vibration dampening member 37 in. contact with its outer face, each spring arm 13 and its vibration damping member 37 being fastened to disk 12 by drive screws 36. More specifically, vibration dampeners 37 are made of the same material as spring arms 13, are mounted against the outer surface of spring arm 13 and are coextensive therewith except that they terminate at their upper ends a short distance below movable contacts 14. Members 37 serve to dampen vibrations of spring arms 13, particularly when magnet means 21 is rotated at higher speeds. Each spring arm 13 also has associated with it at its lower fixed end a conducting strip 15 fastened thereto by drive screws 36. The free ends of strips 15 are connected to baseboard 11 and are provided with terminals for leads 16, it being understood *that each strip 15 has a lead associated with it and that the terminals may be of any conventional form.

A second insulating disk 17 is fixed in parallel spaced relationship with first disk 12 by means of a ring-shaped spacer 40 through which extends an elongated bearing 41. Bearing 41 receives shaft 19* and is of sutficient length to extend through disks 12 and 17 to permit smoother operation. of the shaft. Spacer 40 is maintained in. place by means of screws 34' which are inserted up through apertures 32 in disk 12 into the spacer.

Second disk 17 has secured to its upper face an annular ring 18 larger in outside diameter than disk 17 and made of a conducting material. Ring 18 serves as a second contact, and is so placed as to be radially inwardly of contacts 14. Ring 18 is provided with a plurality of apertures 42 to permit passage of screws 43 which fasten ring .18 to disk 17. A lead 44 is connected to ring 18 in any desired manner to complete the conducting path through the switch. While this second contact has been shown as a single common contact for all of movable contacts 14, an individual contact may be provided for each movable contact 14, in which case, of course, a plurality of leads would be provided.

As has been heretofore briefly explained, magnet means 21 is connected to shaft 19 by a sweep arm so as to rotate therewith. The sweep arm in the preferred embodiment disclosed takes the form of an insulating support disk 29 having a central aperture 45 into which is pressed a sleeve bearing 46 that receives shaft 19 and is fixed thereto by a set screw (not shown). Secured to the bottom of disk 20 by screws 47 which pass down through the disk is flanged bearing member 48 having threaded apertures 49 for the passage of screws 47. If desired, sleeve 46 and flanged bearing member 48 may be made as one piece.

The outer periphery of disk 20 has a radially extending slot 51) cut therein in which permanent magnet means 21 is mounted. Magnet means 21 takes the form of cylindrically shaped permanent magnet 51 of Alnico or similar material. Magnet 51 (see Fig. 3) is encased by a cylindrical housing 52 which is fastened at its upper side as by welding or soldering or the like to a flat plate 53 (see Fig. 2). Plate 53 is provided with slots 54 at either side through which extend screws 55 to permit fastening plate 53 to sweep arm 20. Slots 54 allow adjusting of magnet means 21 inwardly and outwardly. Of course, plate 53 and housing 52 are constructed of nonmagnetic material so as not to distribute the flux.

To facilitate focusing of the magnetic field produced by permanent magnet 51, a soft iron, substantially triangular piece 56 having a flattened outer face 56a is butted against the outer pole of magnet 51. Prongs 57 may be struck out of housing 52 and bent inwardly against focusing piece 56 to hold it in place. The outermost flat face 56a of focusing piece 56 is so placed as to be radially inwardly of the upper ends of spring arms 13, as shown in Fig. 1.

In operation, shaft 19 is rotated, thus sweeping magnet means 21 past the upper ends of spring arms 13. As the magnet passes each spring arm 13, the arm is drawn inwardly as shown in Fig. 3, thereby closing movable contact 14 against ring 18. Each spring arm 13 thus moves from an unbiased position in which movable contact 14 is spaced from ring 18 to a biased position in which con tact 14 engages ring 18. Obviously, the circuit is then completed through leads 16 and 44 to the electrical device connected thereto. Of course, as the magnet passes on, spring arm 13 returns to its unbiased position when the spring force is greater than the force of the magnetic field. It is to be noted in Fig. 3 that outer fiat face 56a of magnet means 21 does not engage spring arm 13 when the circuit is completed and therefore contact friction and noise are eliminated.

The width of spring arms 13, the spacing d between adjacent arms and the force of the magnetic field created by magnet means 21 are so adjusted that only one movable contact 14 engages ring 18 at any particular time. The force of the magnetic field may be varied by moving the entire magnet means inwardly and outwardly within the limits of slots 54 and by varying the shape of focusing piece 56. Thus, flat face 56a may be made more or less wide as desired.

Because there is no friction or mechanical abrasion involved in closing the contacts, but rather only magnetic force, the power required to rotate shaft 19 is small.

If a motor is used, it may therefore be of smaller capacity than for a mechanical switch. The small power requirement adapts the switch disclosed for us as an explosion proof switch, for example, since the switch may be enclosed in a non-magnetic housing and power supplied by a small bar magnet mounted on top of shaft 19 and driven by a similar magnet outside the enclosure and opposite the first magnet.

Since there is no sliding on the contact area, contact noise is eliminated. To prevent oxidation on the contacts the surface of the contacts may be gold plated and the switch mounted in a dust proof enclosure,

While the spring arms 13 and movable contacts 14 carried thereby are disclosed as being equally spaced, the spring arms could be spaced so as to produce any desired switching pattern. The spacing may be as wide as desired, of course, and the limit on how close the spacing may be depends on the speed of rotation, among other factors. This design of switch operates very satisfac torily at slow and moderately high speeds.

While a preferred embodiment has been disclosed, it is understood that one skilled in the art may make modifications without departing from the principles of the present invention, and said invention is to be limited only by the claims appended hereto.

For example, various types of spring arms may be utilized, it being possible to resiliently mount the movable contacts in various ways. Further, the converse mode of operation may be adopted, i.e., have the permanent magnet attract a movable contact away from a fixed contact so as to open each circuit successively and selectively as the magnet sweeps by. Still further, ring 18 may be made to rotate with shaft 19 so as to maintain the contact surfaces clean and counteract any arcing effects at the contact faces.

I claim:

1 1. In a rotary switch, the combination comprising: a base; a shaft supported by the base; a permanent magnet adjustable means for securing the permanent magnet to the shaft with a magnet pole face directed radially outward from the shaft for rotation relative to the base, said means permitting radial adjustment of the permanent magnet; a soft iron focusing piece mounted against the permanent magnet pole face and having an outer face narrower than the permanent magnet pole face for focusing the magnetic flux into a narrow radially-directed bundle at such outer face of the focusing piece; a plurality of elongated magnetically-attractable spring arms individually having one end secured in fixed relation to the base for supporting the other end a relatively short distance outwardly from the rotary path of the outer face of the focusing piece, these other ends being spaced 1 around such rotary path so as to be sequentially attracted by the focused flux of the permanent magnet when such magnet is rotated; and an electrical contact member mounted adjacent each of the spring arms and supported in fixed relation to the base so that as the spring arms are sequentially flexed by the magnetic attraction of the focused flux the state of electrical contact between the spring arms and the contact members is altered.

2. In a rotary switch, the combination comprising: a base; a shaft supported by the base; a sweep arm secured to the shaft for rotation relative to the base; a permanent bar magnet attached to the sweep arm and having a pole face directed radially outward from the shaft; a soft iron focusing piece mounted against the permanent magnet pole face and having a cross section which decreases as the radial distance from the shaft increases to provide for the focusing piece an outer face of smaller area than the permanent magnet pole face thereby to focus the magnetic flux into a narrow radially-directed bundle at such outer face of the focusing piece; a housing member for securing the focusing piece to the permanent magnet; means for securing the housing member to the sweep arm permitting radial adjustment of such housing member; a plurality of elongated magnetically-attractable spring arms individually having one end secured in fixed relation to the base for supporting the other end a relatively short distance outwardly from the rotary path of the outer face of the focusing piece, these other ends being spaced around such rotary path so as to be sequentially attracted by the focused flux of the permanent magnet when such magnet is rotated; and an electrical contact member mounted adjacent each of the spring arms and supported in fixed relation to the base so that as the spring arms are sequentially flexed by the magnetic attraction of the focused flux the state of electrical contact between the spring arms and the contact members is altered.

3. In a rotary switch, the combination comprising: a base; a shaft supported by the base; a sweep arm secured to the shaft for rotation relative to the base; a permanent bar magnet attached to the sweep arm and having a pole face directed radially outward from the shaft; a soft iron focusing piece mounted against the permanent magnet pole face and having an outer face narrower than the permanent magnet pole face for focusing the magnetic flux into a narrow radially-directed bundle at such outer face of the focusing piece; a tubular housing encasing the permanent magnet and having prongs formed therein engaging the focusing piece; means for securing the tubular housing to the sweep arm permitting radial adjustment of such housing; a plurality of elongated magneticallyattractable spring arms individually having one end secured in fixed relation to the base for supporting the other end a relatively short distance outwardly from the rotary path of the outer face of the focusing piece, these other ends being spaced around such rotary path so as to be sequentially attracted by the focused flux of the permanet magnet when such magnet is rotated; and an electrical contact member mounted adjacent each of the spring arms and supported in fixed relation to the base so that as the spring arms are sequentially flexed by the magnetic attraction of the focused flux the state of electrical contact between the spring arms and the contact members is altered.

References Cited in the file of this patent UNITED STATES PATENTS 1,601,205 Fisher et al. Sept. 28, 1926 1,676,979 Cheeseman July 10, 1928 2,310,138 Whittaker Feb. 2, 1943 2,459,930 Fink Jan. 25, 1949 2,475,819 Coake July 12, 1949 2,740,860 Walsh Apr. 3, 1956 2,760,027 Riley Aug. 21, 1956 FOREIGN PATENTS 520,540 Germany Mar. 12, 1931

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