IL26818A - Magnetic actuator device with coupled rotors - Google Patents

Description

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PATENTS FORM No.3 PATENTS AND DESIGNS ORDINANCE GNETIG ACTUATOR DEVICE WITH COUPLED ROTORS " "w D'nwn DJ? - »ysg »t?3*a ij?nn« SPECIFICATIO =t/We TESTOR R/C CORPORATION, an Illinois Corporation, of 222.Paye....Avenu do hereby declare the nature of. this invention and in what manner the same is to be performed, to' be particularly described and ascertained in and by the following statement: — - .

This invention relates to improvements in polarized self-neutralizing servo motors for use to effect a proportional system for operating a control means such as the steering mechanism of a radio-controlled model vehicle to which the output shaft or armature of the motor is connected.

The advantages of such a proportional control system are recognized and prior devices have been commercially successful in their use for operating a steering mechanism of a radio-controlled model vehicle. One prior device actuator employed a permanent magnet rotor which was made to oscillate in response to selective direct current energization of the coil windings around a ferrous core to which ferrous pole pieces are connected. The art failed to provide a device wherein a pair of permanent magnet rotors were oscillated for transmitting the torque of one rotor to the other in such a manner that an increase of approximately two to three times the torque output can be realized over that of the single rotor unit with no increase in voltage or amperage applied to the electro-magnet, and without increase in the size or cost of the device as compared to prior devices. According to the invention there is provided a light-weight magnetic actuator for controlling a model vehicle comprising, an electromagnet having a core and a winding on the core, a pair of magnetizable assemblies connected to opposite ends of the core and selectively energized thereby, said assemblies arranged on opposite sides of and spaced from the core, each assembly including magnetizable pole pieces disposed in a common plane to complete a separate magnetic circuit, and a permanent magnet member mounted in a plane parallel to said common plane, each magnet member having a rock shaft joined for movement therewith for providing a mechanical output, and a non-magnetic coupling arrangement connecting said magnets to provide a common mechanical output from both of said rock shafts.

In order that the invention be clearly understood a preferred embodiment will be described in detail with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic view showing the magnetic actuator device embodying the invention installed in a representative operational system for which the invention is par-ticularly suitable.

Figure 2 is a perspective view of said magnetic actuator on an enlarged scale.

Figure 3 is a median sectional view taken longitudinally through said magnetic actuator.

Figure 4 is a sectional view taken through said actuator along the lines 4-4 of Figure 3 and in the general direction indicated.

Figure 5 is a plan view of the actuator having a modified form of coupling means for connecting the magnetic rotors.

Referring now to the drawings , in Figure 1 there is shown diagrammatically the magnetic type actuator or servo-motor embodying the invention installed in a radio- controlled model automobile so as to effect proportional control of the steering mechanism of said automobile. The illustration shows said actuator in an operational environment for which it is very suitable, that is, for operating the linkage to the front wheels of an automobile which requires considerable torque. As seen in Figure 1, the linkage to the front wheels 10 of the automobile 12 includes a tie rod 14 which is connected by the links 16 to the front wheels. Extending rearwardly from the tie rod is a linkage 18 which terminates in a loop 19 operably connected to the magnetic actuator or servo-motor embodying the invention which has been identified generally by the reference character 20.

The linkage 18 is rotated reciprocably as represented by the arrow 21 by the actuator 20 and said rotary movement is then translated into a linear movement which likewise is a reciprocating one as represented by the arrow 22 along which the tie rod is moved to turn the wheels in the direction indicated by the arrows 23. Since the specific structure of the steering mechanism for the wheels and the linkage for operating said steering mechanism through the actuator 20 is not a part of the herein invention and further since these mechanical elements can vary in structure within wide limits, it is not deemed necessary to describe or to illustrate the Referring to Figure 2, the servo-motor 20 includes an electromagnet shown with a ferrous core 61 which is provided with a hole for a bolt 31 as best seen in Figure 3. Also shown is the coil winding 32 which can be either a single coil of wire that is center tapped at mid-resistance with proper terminal connections, or a pair of coils, wound in series, with the series connection serving as the center tap. The core 61 supports a pair of plastic end flanges or discs 33, one of said flanges 33 mounting three terminals or con-tacts 34, 35 and 36 for the terminal leads and center tap of the coil to which electrical leads 37, 38 and 39, respectively, are connected. As understood in the art, the coil 32 is connected to be selectively energized from a battery or direct current supply by means of the radio receiver which controls operation of a suitable switching arrangement.

Where the switching arrangement connects the battery supply across leads 37 and 38, the core 61 is magnetized to achieve one condition of polarity for the pole pieces. To reverse the condition of polarity of the pole pieces, the battery supply is connected across the leads 38 and 39, maintaining the same electrical polarity at center tap 38. Thus the lead 38 is a center tap and leads 37 and 39 are terminal leads for selectively energizing the coil 32 from a battery supply, not shown, in response to signal received from a pulsed transmitter by a receiver in the model vehicle.

Referring to Figures 3 and 4 herein, there is provided from each end of the core 61 . The first pair of polar arms 40 and 42 are provided, at their extremities remote from the core, with pole pieces 43 and 44 respectively. Each arm is an integral part or extension of the pole piece. Each of said pole pieces is a flat strip of ferrous metal of uniform widt and thickness substantially semi-circular in outline at a right angle to the polar arm of which it is a part. ThuSj the pole pieces 43 and 44 are aligned facing each other in a common plane spaced from the axis of the core and with their respective extremities 45 , 45 ' spaced apart to provide air gaps 46 and 46 ' , respectively. The pole pieces 43 and 44 are joined to a non-magnetic disc 47 .

The disc 47 has an integral tubular bearing 48 for a rotatable shaft 49. The rotatable shaft 49 has a right angle extension 50. The shaft 49 fixedly supports a permanent magnet 51 magnetized along its diameter, which is rotatable with the shaft, the shaft 49 extending axially through the center of the disc 47 and being bent to facilitate secural, as by soldering and cementing to the surface of the magnet 51.

The pole pieces are secured to the disc 47 by the hollow non-ferrous rivets 55 , 56 , 58 and 60. Rivets 55 and 60 are spaced apart 180° , as are rivets 48 and 56 , on the pair of pole pieces, and each rivet hole provides a region of reduced cross-sectional area in each arm of each pole piece as a flux restriction. Rivets 55 and 56 hold the disc 47 to the o e ie nd i and 0 hold he ol i 44 to the disc 47, the flux restrictions at the rivet locations serving as magnetic indexing means .

Further, the actuator 20 has a second pair of polar arms 40a and 42_a which are connected to the core 61. The polar arms 40a and 42a have, as integral parts, pole pieces 43a and 44a respectively. In fact, the invention provides a second rotor assembly on the opposite side of the core which is identical to the rotor assembly heretofore described. Consequently, the same ordinal numbers have been assigned to the corresponding elements of said rotor assembly with the additional use of the sub-script "a" to distinguish one from the other. The pair of similar rotor assemblies are each on opposite sides of the common core to which they are connected. Thus the right angle extensions 50 and 50a of the shafts 49 and 49a respectively are coupled together adjacent their free extremities at 52 and 52^ by a coupling member 54 of either non-ferrous or discontinuous ferrous material forming two coupling stubs connected by a non- ferrous, loose fitting, insulating sleeve 54'. The use of sleeve 54' to connect the two coupling stubs allows some misalignment of bearings 48 and 48a in assembly without the resulting torsional output losses which a firm coupling of he two rotors could cause. The coupling member 54 is operably connected to the loop 19 by passing therethrough, as shown in Figure 2.

The magnets of the two rotor assemblies are arranged are rotated in the same angular direction concurrently. The torque output end of the rotors thereby is coupled one to the other and an increased total output is realized from the single electromagnet without any increase in voltage or amperage thereto.

A commercial embodiment of this invention has been successfully marketed with entirely unexpected and unusual results. The torque output from the actuator 20 was approximately two to three times the output realized from a single actuator. The output of a device embodying a single rotor actuator was measured at nine to nine and one half inch grams of torque. The output of a practical device using the double rotor actuator 20, using the same size electromagnet and rotor assembly, was measured at twenty-four to twenty-seven inch grams. The electromagnet of the device 20 of the said device tested consisted of 1050 turns of No. 34 copper wire insulated in each of the two coils. Voltage applied in both cases was 4.8v. from fully charged nickel cadmium cells of 1.2 ampere hours capacity with a resultant current drain of 160 milliamperes .

The reason for obtaining this unexpected and unusual result is not entirely understood but can be hypothesized as follows: In the single rotor configuration actuator, the lines of magnetic force created in the core of the electromag-net by energization with direct current of one coil, or the other, attempt to close the circuit magnetically by following pieces. The pole pieces will accept lines of magnetic force only to a point of saturation, (usually considered to be approximately 110,000 lines of force per square inch of cross-sectional area in cold rolled steel) . At saturation of the pole pieces, t e reluctance of the magnetic circuit is raised to a level where no more lines of magnetic force may enter the pole pieces. Leakage of lines of force will then occur through air from one end of the coil core to the other since this now has become the new path of least reluctance.

In the two rotor configurations herein, with rotors coupled together, the addition of a second pair of polar arms and pole pieces furnishes a new path of lower reluctance than the air path existant in the single rotor configuration. The addition of the two polar arms and pole pieces creates a total flux path of approximately one-half the reluctance of the path of the single rotor configuration, plus the advantage of gathering in a portion of the stray or lost lines of force wasted in the single rotor configurat on. It is be-lieved that the more than double torque output at the same voltage and amperage is the result of more efficient utilization of available lines of magnetic force created by the energized electromagnet. It is very probable also that the effect of having two permanent magnets in the flux path aids in shaping and confining the stray lines of force that occur above the saturation level of the polar arms .

The invention contemplates applying the torque output from the actuator 20 other than from the coupling member connecting the rotor assemblies. Looking at Figure 5, the actuator 20 has been modified to couple the magnets 51 and 51a by means of a coupling member 62 which is formed by extending the inner end of each shaft 49 and 49a into an L-shaped extension 64 and 64a. The extremities of these extensions are then coupled by a sleeve 66 of insulating material thus coupling cthe rotor assemblies from the inner ends of the shafts 49 and 49a. Thereafter, the output end of one shaft 49 or 49a is connected to the coupling loop 19 or instance. For instance, the extension 50 can be dispensed with and the extension 50b formed for connection to operate the control device by means of a torque rod or push rod.

HAVING NOW particularly described and ascertained tJio nature of my /our said invention and in what manner the sam ; is to be performed, I/We declare that what I/We claim is ·

Claims (10)

1. A light-weight magnetic actuator for controlling a model vehicle comprising, an electromagnet having a core and a winding on the core, a pair of magnetizable assemblies connected to opposite ends of the core and selectively energized thereby, said assemblies arranged on opposite sides of and spaced from the core, each assembly including magnetizable pole pieces disposed in a common plane to complete a separate magnetic circuit, and a permanent magnet member mounted in a plane parallel to said common plane, each magnet member having a rock shaft joined for movement therewith for providing a mechanical output, and a nonmagnetic coupling arrangement connecting said magnets to provide a common mechanical output from both of said rock shafts .

2. A magnetic actuator according to Claim 1 in which said rock shafts are coupled together by said coupling arrangement .

3. A magnetic actuator according to Claim 1 or Claim 2 in which each rock shaft is secured to a surface of the magnet associated therewith, and each rock shaft has an output end connected with the output end of the other rock shaft by said coupling arrangement.

4. A magnetic actuator according to Claim 3 in which said output ends of the rock shaft are an extension of that portion of the shaft secured to the magnet surface.

5. A magnetic actuator according to any one of Claims 1 through 4 in which said assemblies are substantially identical .

6. A magnetic actuator according to Claims 1 or 2 in which said rock shafts each have an output end remote from the magnet associated therewith and said output ends are coupled together by means of a non-magnetic coupling sleeve.

7. A magnetic actuator according to Claims 3 or 4 in which said output end is remote from the magnet associated therewith.

8. A magnetic actuator according to any one of the preceding claims in which indexing means are provided on each pair of pole pieces.

9. A magnetic actuator according to any one of Claims 1 through 5, 7 or 8 in which said coupling means comprises a non-magnetic sleeve.

10. A magnetic actuator substantially as described in the specification with reference to the accompanying drawing. Tel-Aviv, the 6th., November 1966 / .