US2428671A

US2428671A - Vibration apparatus

Info

Publication number: US2428671A
Application number: US534830A
Authority: US
Inventors: Earle L Kent; Robert C Treseder
Original assignee: Conn Ltd C G
Current assignee: CG Conn Ltd
Priority date: 1944-05-09
Filing date: 1944-05-09
Publication date: 1947-10-07
Anticipated expiration: 1964-10-07

Description

Oct. 7, 1947. E. L. KENT ETAL VIBRATION APPARATUS Filed May 9, 1944 Patented Oct. 7, 1947 VIBRATION APPARATUS Earle L. Kent, Elkhart, Ind., and Robert C. Treseder, Dayton, Ohio; said Kent assigner to C. G. Conn, Ltd., Elkhart, Ind., a corporation of Indiana Application May 9, 1944, Serial No. 534,830

12 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to vibration apparatus and more particularly to a device having a tunable reed for measuring vibrations.

One of the objects of the invention is to provide vibration apparatus which is simple in construction and which can be tuned to any desired resonant frequency within the range of the apparatus.

Another object of the invention is to provide vibration apparatus in which the reed may be tuned by movable supports engaging the reed and fixed guide plates beside the reed. According to one desirable feature, the resonant frequency of the reed may be indicated by the position of the supports.

Still another object of the invention is to provide vibration apparatus in which the reed is shaped to cause a substantially straight line variation in resonant frequency with changes in effective length.

The above and other objects and advantages of the invention will be more readily apparent from the following description when read in connection with the accompanying drawing, in which- Figure 1 is a perspective view of a vibration measuring instrument embodying the invention;

Figure 2 is a longitudinal central section of the instrument;

Figure 3 is a horizontal section on the line 3-3 of Figure 2;

Figure 4 is a transverse section on the line 4--4 of Figure 2; and

Figure 5 is a partial transverse section of an alternative guide construction.

As shown on the drawing the instrument comprises a base I which may be a casting having spaced sides II of reduced height for a portion of their length, a cover I2 open at its ends may t over the Ibase and be secured thereto by screws I3 to enclose the operating parts. One end of the cover is closed by an end flange I4 on the base and the other end by a transparent plate I fitting at its edges into slots in the (sides I I. As shown the plate I5 is graduated into a Vertical scale, one side of which may be marked for direct reading and the other for reading in a mirror I6 pivoted to the cover.

A flexible vibratory reed I'I is mounted on the base, being secured at one end to the reduced portions of sides II and extending longitudinally of the base With its other end free to vibrate adjacent the plate I5. The free en d of the reed may be weighted by strips I8 if desired, the weighting depending upon the frequency range of the instrument. It will also be understood that the frequency range may be controlled by varying the length and stiffness of the reed.

The reed is adapted to be tuned by adjusting its eiective length and for this purpose a block I9 is supported on a screw 2| which is rotatably mounted in the base and has a thumb wheel 22 outside of the end ange I4. The block is threaded on the screw to be moved longitudinally of the base and reed as the screw is turned. An angular extension 23 is secured to the block and forms therewith a yoke straddling the reed with supporting rollers 24 carried by the block and extension and engaging the opposite faces of the reed.

The rollers 24 are rigidly held against vertical movement rigidly to clamp the reed by guide plates 25 of the same thickness as the reed secured to the reduced portions of sides II and lying in the same plane as the reed when it is in its normal or neutral position. The rollers 24 span the gap between the edges of the reed and guide plates and are pressed iirmly against the guide plates so that as the yoke is moved the rollers clamp the reed at diilerent points in its length to vary its effective length and consequently its resonant frequency. Preferably the extension 23 is made resilient to exert a spring clamping force through the rollers on the reed and guides so that they will be rmly gripped regardless of slight Variations in thickness.

In order to support the reed so that it will not buckle when the rollers are moved toward its fixed end and so that the part of the reed between the rollers and fixed end of the reed will not vibrate, the block I9 and extension 23 may fit closely against the opposite faces of the reed slidingly to clamp it between them. Preferably the block and extension clear the reed slightly and have pads 20 of yielding material such as felt cemented to their faces and engaging the reed. In this way the reed is held against buckling when the block is moved longitudinally thereof and at the same time the part of the reed between its mounted end and the rollers is held against vibration,

The adjusted frequency of the reed may be indicated by providing in the cover an elongated slot 26, having scale graduations along its length, through which a reference mark on or the edge Qi 1211.@ block I9 may be observed. The scale graduations may be calibrated in terms of frequency so that a direct reading of the adjusted frequency of the reed is obtained.

We have found that the relationship between the free length of a straight reed and its resonant frequency does not follow a straight line and in order to produce a straight line relationship so that the scale on the slot 26 may be uniform the reed is shaped to provide different sections at different points in its length. It is preferable to make the reed of uniform thickness so that the reed and guide plates 25 may be plane plates of the same uniform thickness and may, if desired, be cut from a single sheet. Accordingly the reed is shaped by cutting away its sides as shown in Figure 3 at 21 so that the reed has a minimum width adjacent its mounting on the sides H and tapers out to full Width adjacent the forward ends of the guide plates 25. With the reed shaped as shown so that its sides are bowed out slightly, its free length and reso- A nant frequency have a straight line relationship so that the scale on the slot 26 can be uniformly graduated. For a non-linear scale in which the graduations are spaced wider at one part than at another other reed shapes may be employed.

Figure 5 illustrates an alternative guide plate structure, parts therein corresponding to like parts in Figures 1 to 4 being indicated by the same reference numerals. In this construction, each of the guide plates is formed by a pair of thin plates 29 bowed in transverse section and clamp at one edge on the casing sides Il so that the opposite edges tend to spring apart as shown. Each of the plates 29 is of approximately half the thickness of the reed, preferably being slightly less than half the reed thickness, so when the plate edges are pressed together, the total thickness will be substantially the same as the reed thickness.

With this construction the rollers will press the edges of the plates 29 together and at the same time will rmly clamp the reed. If there is any variation between the reed thickness and the total thickness of the guide plates the rollers will clamp the reed tightly and will be rmly held by the resilient action of the plates.

In using the device the base I0 is placed in contact with a vibrating member so that the vibrations thereof will be transmitted to the reed to cause it to vibrate. When the reed is so adjusted that its resonant frequency is different than the frequency of the vibrations its amplitude of vibration Will be quite small. By turning the thumb screw 22, the resonant frequency of the reed can be adjusted to be the same as the frequency of the vibrations at which time the vibration of the reed will be maximum as observed on the scale on the transparent end plate l5. At this time the frequency of the vibration is indicated by the position of the yoke relative to the scale on the slot 26 and the amplitude thereof can be observed directly on the scale on the end plate. It will be understoo-d that instead of reading the amplitude directly on the end plate any desired transmission means might be employed to obtain remote readings such, for example, as the pickup apparatus more particularly described and claimed in either of our copending applications, Serial Nos. 534,831, led May 9, 1944, or 534,832, filed May 9, 1944.

While one embodiment of the invention has been shown and described in detail herein, it is understood that this is illustrative only and is not intended as a definition of the sope of the 4 invention, reference being had to the appended claims for this purpose.

What is claimed is:

1. Vibration apparatus comprising an elongated vibratory reed xedly mounted at one end with its other end free to vibrate, a guide plate lying beside the reed and in the plane of the reed when the reed is in its neutral position, supporting members engaging the opposite sides of the reed and guide plate, and means to move th'e supporting members longitudinally of the reed thereby to vary the effective length of the reed.

l2. Vibration apparatus comprising an elongated vibratory reed fixedly mounted at one end with its other end free to vibrate, guide plates on opposite sides of the reed lying in the plane of the reed when it is in its neutral position, supporting members engaging the opposite faces of the reed and guide plates, and means to move the supporting members longitudinally of the reed to vary its effective length.

3. Vibration apparatus comprising an elongated vibratory reed xedly mounted at one end with its other end free to vibrate, guide plates on opposite sides of the reed lying in the plane of the reed when it is in its neutral position, supporting rollers engaging the opposite faces of the reed and guide plates, and means to move the rollers longitudinally ofthe reed to vary its effective length.

4. Vibration apparatus comprising a casing, a reed supported at one end in the casing with its other end free to vibrate, guide plates xedly mounted in the casing beside the reed, a yoke member slidably mounted in the casing, supporting members carried by the yoke member and engaging the opposite faces of the reed and plates, means to move the yoke member longitudinally of the reed to vary the effective length of the reed, and cooperating indicia on the casing and yoke member to indicate the resonant frequency of the reed when the yoke member is in different positions.

5. Vibration apparatus comprising an elongated flat reed secured at one end with its other end free to vibrate, the reed being of substantially uniform thickness and varying in width from a point adjacent its secured end to a point spaced therefrom, guide plates of the same thickness as the reed on the opposite sides thereof and lying in the plane of the reed when it is in its neutral position, supporting members engaging the opposite faces of the guide plates and reed, and means to move the supporting members longitudinally of the reed to vary its effective length.

6.. Vibration apparatus comprising an elongated flat reed of uniform thickness substantially throughout its length secured at one end with its other end free to vibrate, the width of the reed varying from a minimum adjacent said one end to a maximum at a point spaced therefrom, and adjustable supporting means engaging the reed on its opposite faces and movable lengthwise thereof to vary its effective length whereby the resonant frequency of the reed and its effective length will have a substantially straight line relationship.

7. Vibration apparatus comprising an elongated flat reed of uniform thickness substantially throughout its length secured at one end with its other end free to vibrate, the width of the reed varying from a. minimum adjacent said one end to a maximum at a point spaced therefrom, guide plates lying on opposite sides of the reed, supporting means engaging the opposite faces of the @MM M0011 reed and guide plates, and means to move th'e supporting means longitudinally of the reed to vary its eifective length.

8. Vibration apparatus comprising an elongated iiat reed of uniform thickness substantially throughout its length secured at one end with its other end free to vibrate, the width of the reed varying from a minimum adjacent said one end to a maximum at a point spaced therefrom, guide plates lying on opposite sides of the reed, supporting means engaging the opposite faces of the reed and guide plates, means to move the supporting means longitudinally of the reed t0 vary its effective length, and means to indicate th'e position of the supporting means and thereby the resonant frequency of the reed.

9. Vibration apparatus comprising an elongated at reed secured at one end with its other end free to vibrate, guide means including a pair of resilient plates of substantially half the thickness of the reed secured face to face beside the reed with their edges adjacent the reed tending to spring apart, and supporting means engaging the opposite faces of the reed and guide plates and squeezing said edges of the guide plates togeth'er.

10. Vibration apparatus comprising an elongated iiat reed secured at one end with its other end free to vibrate, guide means including a pair of resilient plates of substantially half the thickness of the reed secured face to face on each side of the reed with their edges adjacent the reed tending to spring apart, supporting means extending transversely of the reed and engaging the opposite faces of the reed and guide plates together, and means to move the supporting means longitudinally of the reed.

11. Vibration apparatus comprising an elongated iiat reed, means mounting the reed adjacent one end leaving its oth'er end free to vibrate. a support movable longitudinally of the reed, rollers carried by the Support engageable with the opposite faces of the reed to vary its effective length as the support is moved, and parts on the support engaging the opposite faces of the reed between the mounting means and rollers.

12. Vibration apparatus comprising an elongated flat reed, means mounting the reed adjacent one end leaving its other end free to vibrate, a support movable longitudinally of the reed, rollers carried by the support engageable with the opposite faces of the reed to vary its effective length' as the support is moved, and yielding pads carried by the support and engaging the opposite faces of the reed between the mounting means and rollers.

EARLE L. KENT. ROBERT C. TRESEDER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,687,507 Perkins Oct. 16, 1928 2,301,291 Kolesnik Nov. 10, 1942 2,356,229 Dunlap et al Aug. 22, 1944 185,728 Cook Dec. 26, 1876 2,260,210 Bourne Oct. 21, 1941 2,296,213 Kretzschmar Sept. 15, 1942 FOREIGN PATENTS Number Country Date 440,319 Great Britain Dec. 24, 1935 548,403 Germany Apr. 15, 1932 181,880 Switzerland June 2, 1936