Electromagnetic Vibrator Having Means For Changing Direction Of Vibrations

Abstract

An electromagnetic vibrator having spaced apart magnets mounted on an axis, and a drive coil interposed between the magnets, the drive coil being vibrated by energization thereof by an A-C current. The magnets are rotatable about an axis so as to change the direction of vibration of the drive coil. A set of rollers engaging respective generally L-shaped guide plates, the guide plates being coupled to the coil via a plate member, is provided so as to additionally change the direction of vibration of the drive coil. To change the direction of vibration, the rollers are selectively engageable with perpendicular surfaces of the generally L-shaped guide plates.

Description

This invention relates to vibrators producing mechanical vibrations, and more particularly, to electromagnetic vibrators capable of providing vibrational forces in different directions.

Vertical and horizontal vibration tests should usually be conducted on articles, or parts thereof, which will be subject to strong vibrations in use or during transportation in order to check their durability in vibratory environments, whether or not their performance changes in such environments and other effects of vibrators thereon.

Prior art electromagnetic vibrators for carrying out the above vibration tests are capable of producing vibrations of the test body only in one direction. Therefore, vertical and horizontal vibration tests generally had to be done by separately using a vertical vibrator and a horizontal vibrator. In the prior art, when using the same vibrator for both vertical and horizontal vibration tests, it was required to provide a vertical vibrating table and a horizontal vibrating table which could be selectively coupled to the vibrator. In either of the above cases, it is necessary to separately mount the test article on the vertical and horizontal vibrating tables for the individual tests. Further, a considerably large space is required for the testing equipment, since more than one vibrator or vibrating table is required.

It is therefore an object of the present invention to overcome the above drawbacks of the prior art vibrator arrangements by providing an electromagnetic vibrator, which is capable of selectively vibrating the test body both in the vertical and horizontal directions without requiring separate vibrator devices and/or vibrating tables.

SUMMARY OF THE INVENTION

The invention comprises an electromagnetic vibrator, which includes two magnets symmetrically arranged with respect to the same axis and spaced from each other along the axis such that a pole of one polarity of one magnet faces the opposite polarity pole of the other magnet, the magnets being capable of rotation about the axis. A coil is interposed between the two magnets and traverses the magnetic path defined between the two magnets, the coil being wound into a ring-like form along the direction of rotation of the magnets. The electromagnetic vibrator according to the invention, while it utilizes the same basic principles as does the usual electromagnetic vibrator, is so constructed as to permit varying the direction of the magnetic path defined by the magnets by rotating them, to thereby obtain vibration in any desired direction.

In accordance with the invention, since it is possible to obtain vibration in any desired direction by rotating the magnets to a desired position, there is no need for separately mounting the test body on a plurality of vibrating tables for the individual vibration tests. Vibration tests for vibrations in different directions can be done on the same vibrating table. Also, since no more than one vibrator is required, the space or area required for the vibration test apparatus can be reduced.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1A and 1B show a conventional two directional vibrator, FIG. 1A being a section along line 1A--1A in FIG. 1B, and FIG. 1B being a side elevational view;

FIGS. 2A and 2B show an electromagnetic vibrator according to the present invention for use as a vertical vibrator, FIG. 2A being a section taken along line 2A--2A in FIG. 2B, and FIG. 2B being a section taken along line 2B--2B in FIG. 2A;

FIG. 3 is a view similar to FIG. 2A but showing the same vibrator for use as a horizontal vibrator;

FIG. 4 is a front elevational enlarged view illustrating the roller mechanism of the present invention; and

FIG. 5 is a bottom plan view, partly in section, of the mechanism of FIG. 4 .

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1A, there is shown a prior art electromagnetic vibrator 1, which is supported on each side via a trunnion 2 on respective support pillars 3 and which is capable of rotation about the trunnions 2. The vibrator comprises a drive coil 6 and a magnet 7 forming a magnetic circuit to drive the vibrator.

Referring to FIG. 1B, on the vibrator 1 is mounted a vertical vibrating table 4, and on one side is disposed a horizontal vibrating table 5.

For carrying out vertical vibration testing with the apparatus of FIGS. 1A and 1B, the vibrator body 1 is held vertical, and the vertical vibrating table 4 is mounted thereon, as shown in FIG. 1B. The test body (not shown) is then mounted on the vertical vibrating table 4, and then the drive coil 6 is energized to cause vertical vibrations. For horizontal vibration testing, the vibrator body 1 is rotated about the trunnions 2 into its horizontal position, and held horizontal. Then, the horizontal vibrating table 5 is coupled on the vibrator 1. Thereafter, the test body (not shown) is mounted on the horizontal vibrating table 5, and then the drive coil 6 is energized to cause horizontal vibrations.

In the above-described conventional apparatus, however, when coupling the horizontal vibrating table 5 to the vibrator 1, the adjustment of the relative horizontal levels thereof requires a high degree of skill. Also, it is necessary to provide equipment for transferring the test body from the vertical vibrating table 4 onto the horizontal vibrating table 5. Further, the transfer of the test body often causes damage thereto and also requires considerable amounts of time. Furthermore, a considerably large area is required for the installation of the transfer equipment in addition to the relatively large vibrator unit and tables.

FIGS. 2 and 3 show an electromagnetic vibrator according to the present invention. FIGS. 2A and 2B show the vibrator in the case in which it is used for a vertical vibrating test, and FIG. 3 shows the same for a horizontal vibrating test.

Referring to FIGS. 2A, 2B and 3, and particularly to FIG. 2B, which is a section taken along line A--A in FIG. 2A, a stationary frame 8 supports a support shaft 9 which is rotatably journaled in frame 8. The support shaft 9 carries two generally C-shaped permanent magnets 10 secured thereto and spaced from each other such that pairs of poles of one magnet respectively face opposite polarity poles of the other magnet. The magnets 10 can rotate with their shaft 9 by rotating a lever 11. Interposed between permanent magnets 10 is a plate member 13 secured at its top to a vibrating table 12. The plate member 13 is formed with a central opening or aperture of a considerably greater diameter than the diameter of the shaft 9 which passes therethrough, and it is provided on its both sides with a drive coil 14 which is wound along the direction of rotation of the permanent magnets 10, as is clearly shown in FIGS. 2A and 3. The vibrating table 12 is supported via an air spring means 15 on the stationary frame 8 by means, for example, of angles 17 secured to frame 8. Other suitable supports can be used.

Guide rollers 16 are provided and are ganged together such that they can be alternatively supported either in their position shown in FIG. 2A or in their position shown in FIG. 3. Generally L-shaped guide plates 17 are secured to the plate member 13. The plate member 13 is guided such that it can reciprocate only in the vertical direction when the guide rollers 16 are in the position shown in FIG. 2A, while it is guided such that it can reciprocate only in the horizontal direction when the guide rollers 16 are in the position shown in FIG. 3.

FIGS. 4 and 5 are enlarged views of one roller 16 and the mechanism for moving the roller 16 in relation to the L-shaped guide plates 17. It is to be understood that the other three rollers and roller moving mechanism are the same or similar to that illustrated in FIGS. 4 and 5. As seen in FIGS. 4 and 5, a guide roller 16 is rotatably mounted to a lever 18, the guide roller preferably being mounted by means of a ball bearing mechanism 22. The lever 18 is pivotally mounted to the frame 8 by means of a pin 19 which is fixed to the frame 8 by means, for example, of screws 23 and mounting block 24. An operating handle 20 is provided at the end of lever 18 for pivoting the lever 18 about the pin 19 so as to change the position of roller 16 relative to the L-shaped guide plate 17. Operating handle 20 for each of the guide rollers may be appropriately ganged together, as desired, so as to provide simultaneous movement of the rollers.

When the roller and lever are in the position shown in solid lines in FIG. 4, the guide plate 17 and vibrating table 12 can vibrate (or reciprocate) only in the vertical direction. When the rollers and levers 18 are moved to the position shown in dashed lines in FIG. 4, the guide plate 17 and the vibrating table 12 can vibrate (or reciprocate) only in the horizontal direction.

As mentioned above, the operating handles and levers 18 for each of the rollers 16 may be ganged together. The ganging mechanism may merely be a mechanical linkage which has not been shown so as to not duly obscure the inventive concept. Alternatively, the handles 20 for the individual rollers 16 may be individually operable, either by hand or by means of additional operating linkages (not shown), as desired.

Vibration of the vibrating table 12 can be brought about by passing A-C current at a frequency f through the drive coil 14. Because the drive coil 14 is disposed to traverse the magnetic path formed by the C-shaped permanent magnets 10, by passing A-C current at frequency f through drive coil 14 there is produced a vibromotive force F proportional to the product of the field and current in the coil 14, which force F is given as

F = BlI

where F is the force (in kilograms), B is the flux density (in gauss), l is the coil length (in centimeters) and I is the coil current (in amperes).

The force F generated by the drive coil 14 in the above manner is transmitted through the plate member 13 to the vibrating table 12 to cause vibration of a test body (not shown) mounted on the vibrating table 12.

When the permanent magnets 10 are arranged such that their poles lie in a vertical plane as shown in FIG. 2, by passing A-C current through the drive coil 14, so that the plate member 13 and vibrating table 12 are vibrated in the vertical direction. Thus, in this case a vertical vibration test can be carried out on a test article mounted on the vibrating table 12.

When the permanent magnets 10 are arranged such that their poles lie in a horizontal plane as shown in FIG. 3, by passing A-C current through the drive coil 14 a horizontal force is produced in the coil 14, so that the plate member 13 and vibrating table 12 are vibrated in the horizontal direction. It is to be noted that in this case the guide rollers 16 are shifted to the position shown in FIG. 3 so that the plate member 13 is guided such that it can reciprocate in the horizontal direction. Thus, in this case a horizontal vibration test can be carried out on a test article mounted on the vibrating table 12.

The vibrating table 12 is mounted to the frame 8 by means of the air spring 15 and angle members 21. This mounting techniquie is used even when the table is vibrated in the horizontal direction. In this case, therefore, the load on the guide rollers 16 is reduced. The rotation of the permanent magnets 10 relative to the table can be simply achieved by rotating the lever 11 which is connected to shaft 9. Furthermore, vibrations not only in the vertical and horizontal directions but also in any other desired direction can be obtained by appropriately arranging the permanent magnets 10 and guide rollers 16 at a desired position, such as a position intermediate their two end positions.

While a preferred embodiment of the invention has been described in the foregoing, it is by no means limiting and various changes and modifications can be made to the above-described embodiment without departing from the scope and spirit of the invention. For example, the drive coil 14 may be provided only on one side of the plate member 13. Also, the permanent magnets 10 may be replaced with electromagnets, and different supports can be used in place of air springs 15.

Claims

I claim:

1. An electromagnetic vibrator providing a vibrating force through energization of a drive coil disposed in a magnetic circuit with A-C current, said vibrator comprising:

two magnets symmetrically arranged on the same axis and spaced from each other along said axis such that a pole pair of one magnet respectively faces opposite polarity poles of the other magnet;

means for rotating said magnets about said axis; and

a drive coil interposed between said two magnets and traversing a magnetic path between said magnets and being vibrated upon energization thereof by said A-C current, said drive coil being wound into a ring-like form along the direction of rotation of said magnets.

2. The electromagnetic vibrator according to claim 1 further comprising a stationary frame accommodating said magnets and said drive coil; a vibrating table supported on said stationary frame so as to be capable of vibration with respect to said stationary frame; and a shaft constituting said axis extending through the opening of said ring-like drive coil and rotatably mounted at opposite ends in said stationary frame, said magnets being each symmetrically secured to said shaft, and said drive coil being carried by said vibrating table.

3. The electromagnetic vibrator according to claim 2 including air spring means supporting said vibrating table on said stationary frame.

4. The electromagnetic vibrator according to claim 2 further including a plate member interposed between said two magnets and secured at one end to said vibrating table, said plate member being formed with a central opening or aperture of a diameter greater than the diameter of said shaft, said shaft extending through said opening, said drive coil being disposed at at least one side of said plate member and secured thereto.

5. The electromagnetic vibrator according to claim 4 wherein said drive coil is comprised of two coils, each of which is secured to opposite sides of said plate member.

6. The electromagnetic vibrator according to claim 4 further comprising generally L-shaped guide plates coupled to said plate member adjacent the corners thereof, and guide rollers extending in contact with respective L-shaped guide plates; means for shifting the positions of said guide rollers relative to said respective L-shaped guide plates and relative to said stationary frame, the direction of vibration of said vibrating table being determined by the positions of said guide rollers relative to said respective L-shaped guide plates.

7. The electromagnetic vibrator according to claim 6 wherein said guide rollers engage a given surface of said respective L-shaped guide plates for a given direction of vibration of said vibrating table, and said rollers engage a different surface, which is perpendicular to said given surface, of said L-shaped guide plates for vibration of said vibrating table in a second direction different from said given direction.

8. The electromagnetic vibrator according to claim 7 wherein said given and second directions are substantially perpendicular to each other.

9. The electromagnetic vibrator according to claim 6 including air spring means supporting said vibrating table on said stationary frame.