US2985856A - Wobbulator devices - Google Patents

Description

May 23, 1961 R. LEGRANQ 2,985,856 WOBBULATOR DEVIXCES Filed April 9. 11957 //V|/E/V 7-08, 0 52 LEP/Q/VD United States Patent WOBBULATOR DEVICES Roger Legrand, Geneva, Switzerland, assignor to Holding Electrosonic S.A., Fribourg, Switzerland, a corporation of Switzerland Filed Apr. 9, 1957, Ser. No. 651,633

Claims priority, application Switzerland Apr. 13, 1956 1 Claim. (Cl. 336-135) Numerous wobbulator devices, that is to say devices for varying alternatively the tuning frequency of an oscillating circuit, are already known. In the technology of ultra-sounds in particular, recourse is often made to emitters of which the frequency is wobbulated, the wobbulation, in general, reaching 20 to 50 periods per second.

A relatively simple construction for wobbulating a generator, with a wobbulation frequency of the order of magnitude indicated above, consists in providing a vibrator carrying a piece of magnetic material which is approached to and withdrawn from a coil of an oscillating circuit of the generator. However, this construction has certain inconveniences in apparatus adapted to measure the thickness, or for the detection of defects by means of ultra-sounds, as the vibrators, in general, lack stability, either with regard to the frequency or the amplitude.

The present invention has for its subject a wobbulator device which does not have this disadvantage, by reason of the fact that it comprises a rotary member driven at a substantially constant speed by a motor, said member carrying at least an element of magnetic material located in such a manner as to pass, at each revolution of the rotary member, in proximity to a coil of the oscillating circuit.

One form of construction of a wobbulator device, forming the subject of the invention, is shown diagrammatically and by way of example in the accompanying drawings, wherein:

Figs. 1 and 2 are respectively views in elevation and in plan of this form of construction.

The wobbulator device comprises a base 1 to which are secured two supports 2 and 3 for a shaft 4 carrying a rotary member constituted by a disc 5. Said latter may be driven at a substantially constant speed by an electric motor 6, carrying a reducing gear 7 and a wheel 8 coated with rubber. The motor 6 is clamped by a screw 9 in a bracket 10, secured to the support 3. The motor 6 is of constant speed and it is possible to adjust the speed at which it is desired to drive the disc by modifying the position of the assembly 6, 7 and 8 so as to impart the desired value to the distance separating the wheel 8 from the shaft 4.

The base 1 is also provided with a support 11, having a hole 12 of non-circular section. A screwed rod 13, of corresponding section, is capable of sliding in said hole, and carries at one of its ends a cup 14 of agglomerated iron, constituting the magnetic core of coil shown diagrammatically at 15. Said coil constitutes, with a condenser 16, the pilot oscillating circuit of a generator of ultra-sonic frequency.

A nut 17, of which the edge is milled, is fitted on the rod 13 and into a groove of the support 11, so as to p HI? enable the rod 13 to be moved axially. The disc 5 carries six covers for the cup 14. Said covers are of elements of magnetic material and are usually formed by agglomerated iron.

When the disc 5 is driven in rotation, the covers 18 pass successively opposite the cup 14, whereby the value of the self-induction coil 15 is modified periodically. This results in a periodic variation of the tuning frequency of the oscillating circuit of the generator, that is to say a wobbulation of said frequency.

The frequency of the wobbulation is determined by the speed of rotation of the disc 5 and by the number of covers 18 which it carries. The amplitude of this wobbulation, that is to say the difference between the maximum and minimum actual frequencies of the oscillating circuits, depends on the variation of the self-induction coil 15 and may be modified by acting on the nut 17 for withdrawing or approaching the cup 14 from 'or towards the covers 18.

The device described is of very simple construction, and therefore has great stability, so that it is particularly advantageous for portable generators capable of being subjected to more or less strong shocks during their employment. It will be understood that this considerable stability may be obtained with constructions other than that shown, as long as there is provided a rotary member driven at a constant speed by a motor, said member carrying at least one element of magnetic material located in such a manner as to come periodically into a position in proximity to a coil of an oscillating circuit. It Will be understood that the variations of the inductivity of the coil are higher when the coil comprises a magnetic core. In some portable stations, it may be of interest to replace the electric motor by a spring motor.

I claim:

As an article of manufacture, a wobbulator unit for alternatively varying the tuning frequency of an oscillating circuit, comprising in combination, a base, a pair of oppositely disposed space-apart front and rear support members mounted on said base, a disc rotatably mounted between said supports, said disc having a front face and a rear face, a plurality of spaced magnetic members each of equal size mounted on the front face of said disc, a clamping bracket carried by the rear support member and having its axis disposed parallel thereto, a motor mounted for axial adjustment in said bracket, a wheel connected to and driven by said motor, said wheel being angularly disposed in relation to the rear face of said disc and in contact therewith to impart rotational movement thereto, an induction coil including a magnetic core mounted on said base facing the front face of said disc and lying in the path of travel of said magnetic members, adjustment means connected with said coil to vary the spacing between said coil and said magnetic members, whereby when said disc is rotated said magnetic members successively cover said core causing intermittent variations in the tuning frequency of said oscillating circuit.

References Cited in the file of this patent UNITED STATES PATENTS 1,271,590 Lefever July 9, 1918 1,811,465 Geloso June 23, 1931 2,014,534 Lutomirski Sept. 17, 1935 2,158,613 Loughlin May 16, 1939 2,553,629 Behr May 22, 1951 2,578,608 Shull Dec. 11, 1951 2,630,529 Mann Mar. 3, 1953 2,636,386 Schultheis Apr. 28, 1953

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