US3341721A

US3341721A - Transducer housing with flexible supports

Info

Publication number: US3341721A
Application number: US418828A
Authority: US
Inventors: Gordon A Vincent
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1964-12-16
Filing date: 1964-12-16
Publication date: 1967-09-12
Anticipated expiration: 1984-09-12

Description

sept. 12, 1967 G. A. VINCENT TRANSDUCER HOUSING WITH FLEXIBLE SUPPORTS 2 Sheets-Sheet l Filed Dec.

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INVENTOR. GORDON A. VINCENT Ilm* s. M f j 1- v4 l E 1M w w 42 2 4 6 Em 11111 A GSS/m Sept. 12, 1967 G. A. VINCENT 3,341,721

TRANSDUCER HOUSING WITH FLEXIBLE SUPPORTS Filed Dec. 16, 1964 2 Sheets-Sheet 2 M La rml [l 1 FIG. 3

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United States Patent O 3,341,721 TRANSDUCER HOUSING WITH FLEXIBLE SUPPORTS Gordon A. Vincent, Seattle, Wash., assignor to Honeywell Inc., a corporation of Delaware Filed Dec. 16, 1964, Ser. No. 418,828 Claims. (Cl. 310-8.6)

This invention relates to improvements in a transducer for converting one kind of energy to another kind of energy and more particularly concerns a mounting that increases the conversion eiiiciency of a transducer.

A problem exiting in the transducer art is to minimize the outof-phase movement of the boundary support points nf the transducer with respect to the main radiating portion of the transducer. The closer a freely supported 'boundary condition can be approximated the greater the conversion eiiiciency of the transducer becomes. In a typical mounting technique the mounting means and the transducer define parallel planes, and the mouting means to some extent is free to move in the same general direction as the transducer. The mounting means is usually clamped at one end and attached to the transducer at the other end. When the transducer exes and is deflected in one direction reaction forces opposing the deflection are exerted at the clamped edges =of the mounting means. The reaction forces so exerted cause a small deflection of the mounting means in a direction opposite to the transducer deiiection causing a loss in conversion efficiency. Accordingly, it is an object lof this invention to overcome this problem.

It is another object of this invention to provide a transducing device with a mounting means that moves or deiects substantially at lright angles to the transducer deflection. Other objects and advantages of this invention will further become apparent in the following description and in the drawings, in which:

FIGURE 1 is a side elevation view of a pair of bender bars with spring mountings attached vto a housing;

FIGURE 2 is a pictorial view of a bender bar transducer with mounting springs attached;

FIGURE 3 is a pictorial view of a pair of bender bars with spring mountings, attached to a housing;

FIGURE 4 is a schematic diagram showing the general movement of a bender bar and associated mounting springs when under energization;

FIGURE 5 is a schematic diagram showing the general movement of a bender bar wherein an alternate embodiment of the mounting springs is used; and,

FIGURE 6 is a schematic diagram depicting prior art transducer wherein the bender bar is parallel, rather than normal, to the mounting means when in an unexed condition and shows the mode of movement. g

In describing the embodiment of the invention illustrated in the drawings, specic terminology will be used for the sake of clarity. Limitation to the specic terms selected is not to be implied but rather it is to be understood that each specic term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.

Turning now to the specific embodiment selected for illustration in FIGURES l and 2, a pair of

bender bars

12 and 14 is supported in a housing comprised of a circular top plate 18 and a bottom plate 20 connected together by a pair of channel members. Only one of the channel members, designated by the numeral 22, is shown. The channel members are not connected directly to

circular plates

18 and 20 but to blocks 26 and 28 connected to the bottom surface of plate 18 and the top surface of plate 20 respectively.

Bender

bars

12 and 14 are comprised of a stack or array ice of bender elements and a rectangular support frame. The stack of bender bar elements is similar in construction and operation to the array of elements shown in FIGURE 5- of a patent granted to Alvin W. Elston et al., No. 3,127,527, dated March 3l, 1964, and assigned to the assignee of the present invention.

The support frame for bender bar 12 comprises top and bottom

rectangular bars

34 and 36 and

side bars

38 and 40. The frame is bonded to the stack of bender bar elements with insulative cement.

Side bars

38 and 40 ane channeled and notched. Notching the bars makes them more flexible.

One end of each of a pair of

flat springs

42 and 44 is clamped to the top surface of bar 34 and the bottom surface of bar 36, respectively, by a clamping means that comprises top and

bottom bars

48 and 50 and a pair of bolts 52 and 54. The heads of bolts 52 and 54 are seated on areas near the opposite ends of the bar 48. Bolt 52 runs vertically downward through a hole in bar 48, a hole in spring 42, a hole in bar 34, the channel of side bar 38, a |hole in bar 36, a hole in spring 44 and a hole in bar 50. Bolt 54 runs vertically downward, through a hole in bar 48, a hole in spring 42, a hole in bar 34, the channel of side bar 40, a hole in bar 36, a hole in spring 44 and a hole in bar 50. The lower ends of bolts 52 and '54 are threaded and have nuts thereon. Compression forces are applied to bender bar 12 by tightening the nuts at the lower ends of 'bolts 52 and S4. The compression forces also clamp surface spring 42 between

bars

48 and 34 and clamp spring 44 between

bars

36 and 50. The nuts rest on areas near the opposite ends of bar 50.

Bender bar 12 is relatively fragile and pre-stressing in compression insures that tensile forces developed in the bar during normal operation, due to exure, do not result in a tension failure. Using this technique, a safety factor can be built into

bender bars

12 and 14.

The other end of each at

spring

42 and 44 is clamped to blocks 26 and 28, respectively, by

clamping blocks

56 and 58. Clamping is accomplished by tightening bolts drawing blocks 26 and 56 together and by tightening

bolts drawing blocks

28 and 58 together.

Bender bar 14 is identical to bender bar 12 and is mounted and connected to the housing in a similar manner. As shown

bender bars

12 and 14 are mounted parallel to each other in a back-to-back arrangement. If the back-to-back arrangement is used a pressure release means (not shown) is normally situated in the space between the bender bars. In certain applications a single bender bar or a coplanar array of bender bars may be used. Depending upon the particular application the spatial arrangement and number of bender bars will vary.

In FIGURE 2 a pictorial View of bender bar 12 and associated

mounting apparatus

42 and 44 is shown.

Leads

55 and 57 are shown connected to alternating surfaces of the elements in the stack. An A C. power source (not shown) is used to energize the bender bar, the bar acting to convert the electrical power to acoustical power.

In explaining the operation reference is made to the schematic diagram of FIGURE 4. FIGURE 4 represents a vertical bender bar 12 fastened at

end points

60 and 62 to

horizontal springs

42 and 44 respectively;

springs

42 and 44 are fastened to a mounting means at

points

64 and 66 lrespectively. The solid lines in FIGURE 4 represent the transducer configuration when bender bar 12 is not tiexed. The dashed lines represent the transducer configuration during a ilexing movement of bender bar 12 in either one of two directions normal to the longitudinal center of bender bar 12. As bender bar 12 ilexes, point 60 describes an arc-like path about point 64, downward and to the left of the original position of point 60 corre sponding to an unflexed bender bar. The downward distance component of the path is labeled y and the leftward distance component is labeled x. In like fashion point 62 describes an arc-like path about point 66 during flexure of bender bar 12, reaching a position at the end of the fiexure that is upward and to the left of the original position of point 62 by distance components y and x respectively. In practice the springs do not flex perfectly equally so that the distance components x and y are not equal for each spring.

FIGURE 4 is exaggerated for purposes of this illustration but it discloses that x is relatively small with respect to y and the translation of the

points

60 and 62 in the x direction is kept to a minimum. On the other hand if the mounting means had been connected parallel to the bender bar as commonly occurs the translation x would be much greater, and a larger out of phase component of energy would be produced when flexure of the bender bar occurs. FIGURE 6 shows in schematic form the aforementioned parallel mounting technique and illustrates the disadvantage. As bender bar 12 bends outward and to the right and compresses a medium (eg. sea water) to form a pressure wave, reaction forces are created at the end points 60 and 62 that cause these points to move backward and to the left. The spring 42 bends in a cw direction around point 64 and spring 44 bends in a ccw direction around point 66 (the

bent springs

42 and 44 are shown as dashed lines). The backward and to the left movement of the end points 60 and 62 rep-resents an out of phase movement of the ends of bar 12 with respect to the outward and to the right movement of the central portion of bar 12. This movement results in decreased eiciency as it produces a pressure wave in a direction backwards and to the left exactly opposite to that desired outward and to the right. In addition the mounting springs 42 and 44 in FIGURE 6 have greater tension forces developed internally than the corresponding mounting springs in FIGURE 4, which results in lower efficiency.

FIGURE discloses, in schematic form, another embodiment of the present invention. Bender bar 12 is shown as connected normal to mid-points 60 and 62 of points 64 and 68 each rigidly fastened to a mounting means. Correspondingly, spring 44' has end points 66 and 70 rigidly fastened to the mounting means. Primed numbers are used in FIGURE 5 to denote elements which correspond with elements in FIGURE 4. It is not to be understood however that a primed element in FIGURE 5 is identical to the unprimed corresponding element in FIGURE 4. It is apparent that the configuration shown in FIGURE 5 completely prevents the horizontal translation of

points

60 and 62. Rather than translation, the reaction forces during fiexure at

points

60 and 62 set up tension forces in springs 42 and 44' respectively.

The flexed transducer configuration is indicated by dashed lines in FIGURE 5. With the embodiment as depicted in FIGURE 5 a rather thin material can be used for

springs

42 and 44 without danger of a buckling failure. A thin material must be used as it must stretch slightly when bender bar 12 fiexes. Proper design must insure that the tensile strength limit is not exceeded. It is to be noted that the illustration of FIGURE 5 is exaggerated for purposes of clarity.

Depending upon the operating environment, bender bars 12 and 14 may be insulated. For example if used in seawater, etc., a shield or boot (not shown) would be used to isolate the bender bars from the surrounding medium.

The advantage of using these methods of mounting a bender bar substantially normal to a pair of mounting springs increases the conversion efficiency of the bender bar by minimizing undesirable translation of the bender bar end regions and thus reducing the production of energy components that are out of phase with the energy components produced by the central regions of the bender bar. Close approximation to a freely supported boundary condition is attained.

It is to be understood that the forms of the invention as herein shown are not exhaustive. Various changes and substitutions can be made and certain features can be utilized independently without departing from the spirit or scope of the invention.

Having thus described my invention, I claim:

1. In a transducing device, the combination comprising:

a housing;

a transducer, flexible along an axis perpendicular to its longitudinal axis, having support points at first and second ends; and

first and second hinge means flexible in one direction 4connected at their ends to said housing, and connected to the first and second support points of the transducer at first and second midpoints on the hinge means, respectively, the flexible direction of each hinge means being substantially parallel to the longitudinal axis of said transducer.

2. The device of claim 1 in combination with:

means for energizing said transducer.

3. In a transducing device, the combination comprising:

a housing;

a transducer, flexible along an axis perpendicular to its longitudinal axis and having support points at its ends;

first and second at metal springs, flexible primarily in one direction, each connected at one end to the housing and connected at the other end to the transducer support points, the flexible direction of each connected spring substantially parallel to the longitudinal axis of the transducer.

4. The apparatus of claim 3 wherein the springs are leaf springs.

5. In a transducer having a member with a longitudinal axis wherein the member distorts under energization, the central part of said member moving in a first direction and the end regions tending to move in a panel substantially normal to the first direction:

a pair of mounting leaf springs connected to the end regions respectively, said mounting members flexible in the plane of movement of the end regions and relatively rigid in the first direction.

References Cited UNITED STATES PATENTS 3,115,588 12/1963 Hueter S10-8.6 3,127,527 3/1964 Elston 340-10 3,199,071 8/1965 Massa 340-10 3,277,433 10/1966 Toulis B10-86 OTHER REFERENCES High Frequency Barium Titanate Transducers for Generating Ultrasonic Waves in Liquids. Journal of the Acoustical Society of America. pp. 1519-1522. Nov. 1959.

MILTON O. HIRSHFIELD, Primary Examiner. I. D. MILLER, Examiner.

Claims

1. IN A TRANSDUCING DEVICE, THE COMBINATION COMPRISING: A HOUSING; A TRANSDUCER, FLEXIBLE ALONG AN AXIS PERPENDICULAR TO ITS LONGITUDINAL AXIS, HAVING SUPPORT POINTS AT FIRST AND SECOND ENDS; AND FIRST AND SECOND HINGE MEANS FLEXIBLE IN ONE DIRECTION CONNECTED AT THEIR ENDS TO SAID HOUSING, AND CONNECTED TO THE FIRST AND SECOND SUPPORT POINTS OF THE TRANSDUCER AT FIRST AND SECOND MIDPOINTS ON THE HINGE MEANS, RESPECTIVELY, THE FLEXIBLE DIRECTION OF EACH HINGE MEANS BEING SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF SAID TRANSDUCER.