US3469119A

US3469119A - Rolling cam actuated piezoelectric voltage source

Info

Publication number: US3469119A
Application number: US574103A
Authority: US
Inventors: David B Parkinson
Original assignee: Clevite Corp
Current assignee: Clevite Corp
Priority date: 1966-04-11
Filing date: 1966-08-22
Publication date: 1969-09-23
Anticipated expiration: 1986-09-23
Also published as: DE1488892A1; GB1124166A; SE357608B; NL6703217A; NL150901B; DE1488892B2

Description

Sept. 3, 1969 o. a. PARKINSON 3,469,119

ROLLING CAM ACTUA'IED PIEZOELECTRIC VOLTAGE SOURCE Filed Aug. 22, 1966 INVENTOR. DAVID B. PARKINSON FIG.3- WWW/14k ATTORNEY United States Patent 3,469,119 ROLLING CAM ACTUATED PIEZOELECTRIC VOLTAGE SOURCE David B. Parkinson, Cleveland Heights, Ohio, assignor to Clevite Corporation, a corporation of Ohio Continuation-impart of application Ser. No. 541,550, Apr. 11, 1966. This application Aug. 22, 1966, Ser. No. 574,103

Int. Cl. H02n 1/04 US. Cl. 3108.7 15 Claims ABSTRACT OF THE DISCLOSURE An electric voltage source having a frame with piezoelectric elements located therein. A rolling cam contact within the frame for compressing and rotating the piezoelectric element therein to generate a voltage.

This invention relates generally to a piezoelectric voltage source and, more particularly, to a rolling cam actuated piezoelectric igniter adapted to be employed for igniting a wide variety of gas fired products such as outdoor barbecues, camp stoves, infrared heaters, ranges, hot water tanks, outdoor lights and the like.

The present application is a continuation-in-part of application Ser. No. 541,550, filed Apr. 11, 1966, assigned to the same assignee, and now abandoned.

In the prior art the voltage sources have been manifestly bulky, required too much effort to operate and were relatively expensive to fabricate. Although these devices have achieved a fairly wide acclaim for their versatility over and above more conventional igniters and for the negligible amount of maintenance required, the commercial acceptance has been on a rather moderate scale.

It is therefore the primary object of this invention to provide a piezoelectric voltage source which exhibits a superior mechanical efficiency over the products of the piror art, and more specifically in which a mechanical advantage system is utilized enabling the reduction of the force which must be applied to actuate the device by as much as a 5 to 1 ratio.

It is a more specific object of the invention to provide a device of the type above described in which a rolling contact mechanism is utilized, obviating the need for sliding surfaces, to obtain an improved mechanical advantage and a more efiicient piezoelectric igniter.

An aspect of the present invention resides in the provision of a piezoelectric voltage source which includes a frame having longitudinally spaced abutments rigid against displacement. A stack of piezoelectric elements is disposed between the abutments. The stack of elements has a first and second end face and a longitudinal axis normal thereto; the first end face bears against one of the abutments while the second end face is spaced relative to and faces the other abutment. A rolling cam mechanism is interposed, in bearing relation, between the second end face and the said other abutment. An actuating mechanism for rotating the cam mechanism relative to the second end face and the said other abutment is effective to cause the frame to move angularly relative to the stack of piezoelectric elements and compress the same in the longitudinal direction against the first named abutment to generate a voltage.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings:

3,469 ,1 l9 Patented Sept. 23, 1969 "ice FIGURE 1 is an exploded view of the invention shown in perspective;

FIGURE 2 is a front view of the piezoelectric igniter, with the outer casing removed, illustrating the relatively unstressed position of the piezoelectric assembly;

FIGURES 2a and 2b are views similar to FIGURE 2 illustrating additional operating characteristics;

FIGURE 3 is a side view of the piezoelectric element voltage source as completely assembled; and

FIGURE 4 is an enlarged cross sectional view of the rolling cam with cam portions thereof exaggerated for illustrative purposes.

Referring now to the drawings, there is shown in FIG- URES l to 3 a frame 10 formed as a relatively flat structure having a longitudinally extending, irregularly contoured, cut-out 11 for receiving a stack of piezoelectric elements 12 therein. The frame 10 is composed of a metallic material which is capable of withstanding longitudinal forces between spaced portions upon working of the device as hereinafter further delineated.

In the preferred embodiment the stack of piezoelectric elements 12 are comprised of, but not limited to, two cylindrical

ceramic elements

14 and 16 composed of barium titanate, lead titanate zirconate or similar polycrystalline materials. Preferably, the elements are encapsulated, except for the end faces, with silicon rubber or similar material, not shown.

The elements are end electroded and polarized parallel to their axis by means of their electrodes. They are assembled in such a manner that they may be said to be mechanically in series and electrically in parallel. Squeezing the elements in the longitudinal direction, i.e., parallel to the axis of polarization, generates a high voltage potential at the center electrode 18 which in the form of a circular metallic late is interposed between the

elements

14 and 16. A suitable cable 20 extends therefrom. The planes of the end faces of the stack 12 are parallel with regards to each other and the longitudinal axis of the stack 12 extends normal thereto.

One end face of the stack of elements 12 and more particularly of element 14 thereof bears against a little metallic plate or shoe 22 which has an H-like configuration and is suitably seated in a complementary cut-out formed in frame 10. Seated in the lower end of the cutout 11 of frame 10 and between the shoe 22 is a wedge-like structure 24. The wedge 24 has a cylindrical surface and the peak thereof is in bearing contact with shoe 22. An effort is made to have the line contact between the wedge 24 and the shoe 22 coincide as nearly as possible with the center line of the elements. In the longitudinal direction the wedge 24 is slightly tapered for reasons which will hereinafter become more apparent. The shoe 22, which incidentally also serves as an electrical ground in the circuit, together with the wedge 24 are considered part of the abutment structure of frame 10 although these components do have additional functions.

At the opposite end of the stack 12 and more particularly between the end face of element 16 and the frame 10 there is interposed a small metallic plate 26 adapted for distributing the load applied upon the stack of elements 12. Another H-like metallic shoe 28 is seated in the extreme end of opening 11 in the frame 10 remote from the first named H-like shoe 22 and securely abuts the frame. More particularly, each of the two H-

like shoes

22 and 28, anchors, because of their projections, e.g., see 30, each individual plate to the frame and transverse movement thereof relative to the frame is prevented. Interposed between the longitudinally spaced

members

26 and 28 is a rolling cam member 32. The cam 32 is an elongated rod-like structure and extends transversely through the frame and is generally formed of a cylindrical rod but includes an out-of-round portion disposed in the area adjacent to and between the plate 26 and shoe 28.

Referring now specifically to FIGURE 4, the rolling cam 32 is fabricated from cylindrical stock and the full diameter is identified as D The roller cam 32 is provided with flat spots 33 on the peripheral surface and with cylindrical portions of gradually decreasing radius leading up to and merging into the flat spots. The flat spots are arranged in such a manner that in the relaxed position of elements 12, the flat surfaces of each spot extend parallel to the adjacent cam follower surfaces of shoe 28 and plate 26. Each cylindrical portion, exclusive of the flat spot, describes a peripheral segment of less than 90' degrees. The diameter D across the flat spots 33 represents the smallest diameter of the cam. The portions removed in forming the cam are shown in outline form.

In order to provide a proper support for the cam member 32 and to facilitate the actuation thereof, there is provided a casing 34 formed of sheet metal or like material, one end thereof having a rectangular slot 36 adapted to receive the end 38 of frame and to restrain the same therein. The opposite end of the casing 34 is U-shaped, see 40, and folded back around the other end of the frame 10. The U-shaped portion 40 of the casing 34 is provided with two openings which are axially aligned to receive in each opening one axial end portion of the rod-like cam member 32. To maintain the cam 32 as well as the

members

26 and 28 in a predetermined location, two circular washers 47 are mounted about the cam and interposed between each transverse end of plate 26 and shoe 28, and the respective portion of the U-shaped portion 40 of the casing 34. One end of the rod-like cam 32 extending through the opening, illustrated on the left hand side in FIGURE 3, see 44, is turned at a right angle to limit the axial freedom of movement of the cam. The opposite end of the cam 32 extends through the other opening, see 43, and is adapted to receive a lever 46 fixedly to the cam by means of a set screw, not shown.

Due to manufacturing tolerances a variation in assembled length may exist in the stack of elements and the

cooperating parts

22, 24, 26, 32 and 28, therefore wedge 24 serves as an adjustment and precompression device and is fabricated with a very small taper (shown in exaggerated form, see FIGURE 3). In the exemplary embodiment the taper is approximately 2. The wedge 24 is sufliciently long to compensate for the various tolerance conditions. In order to facilitate the assembly of the device the casing 34 is provided with an opening 50 through which the wedge 24 may initially protrude during assembly. After the wedge has been moved transversely relative to the frame 10 to establish the proper relationship between the various parts, the unused portions thereof may be cut off so that the end face adjacent the opening 50 will be more or less flush with the plane of the casing 34 adjacent thereto.

-In the preferred embodiment, the

members

22, 24, 26, 28 and 32 are all fabricated of hardened steel.

As shown in FIGURE 2, the assembly of elements 12 maintains normally a slightly slanted or off-center position relative to the frame 10. Upon actuation of the lever 46 the assembly is caused to be moved angularly about the wedge 24 in a counterclockwise direction, i.e., towards the central axis of the device. Simultaneously, in the preferred embodiment, the frame 10 moves angularly in a clockwise direction. FIGURE 2a illustrates a position in which the assembly and the frame have travelled the same distance, but in opposite directions, and are now symmetrically aligned. The rotation or angular movement of the elements 12 is about a rotational axis lying in a plane parallel to the plane forming the end face of the element adjacent to member 22. FIGURE 2b shows the extreme operating position of the frame and the assembly.

The FIGURES 2 to 2b pre-suppose that the cam rotates about a fixed axis. However, it is entirely possible to let the cam move in which case either the assembly 12 or frame 10 is held stationary.

In operation, the cable 20 is placed in operative proximity to a combustible material which is to be ignited and a gap (not shown) is established in conjunction with a cable leading to ground. The lever 46 is either manually, or by a linkage not shown, depressed, which in turn causes the cam 32 to roll about its axis thereby expanding the distance between the

plates

26 and 28. Such expansion causes

members

26 and 28 to yield to the force applied thereto and move in opposite directions as shown by the arrows in FIGURE 4. The stack of elements 12 bearing at one end against the peak of wedge 24 is caused to move angularly as discussed above, together with the plate 26, about the peak of the wedge. The shoe 28 together with all those parts rigidly connected therewith, e.g., frame 10, moves in a direction opposite to that of plate 26. The bottom portion 38 of frame 10 is suitably anchored in slot 36 of casing 34 to permit such movement. The operation of the device results in relative movement between the frame 10, the assembly 12 and the casing 34. Expansion of the longitudinal distance between the

structures

26 and 28 places a high compressive force upon the ceramic element assembly effective to generate and establish a potential on the center electrode 18. The device may be utilized without moving the assembly 12 and frame 10 through the complete operational cycle as shown in FIG- URES 2 to 2b. For some applications it will sufiice to rotate the lever 46 only a fraction of the built-in operational capability.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A piezoelectric voltage source, comprising: frame means having longitudinally spaced abutments rigid against displacement; piezoelectric element means disposed between said abutments and having first and second end faces and a longitudinal axis normal thereto; said first end face being disposed in bearing relation against one of said abutments, said second end face being spaced relative to and facing the other abutment; rolling contact means interposed, in bearing relation, between said second end face and the said other abutment; and actuating means for rotating said cam means relative to said second end face and the said other abutment to effect relative rotary translational movement substantially angular to said longitudinal axis between said frame means and said element means, the rotational axis of the translational movement lying in a plane substantially parallel to the plane forming the second end face of said element means, to compress the element means in the longitudinal direction against the first named abutment to generate a voltage.

2. A piezoelectric voltage source according to claim 1, wherein the longitudinal axis of said cam means extends at right angle to the said axis of said element means and the actuating means is rigidly secured to said cam means.

3. A piezoelectric voltage source according to claim 1, wherein said frame means includes a wedge disposed in bearing relation to the first end face of said element means and having a rounded surface facing said end face, the peak thereof being in line contact with the end face of said element means and coinciding substantially with the central axis of said element means.

4. A piezoelectric voltage source according to claim 3, wherein said wedge is slightly tapered along its axis of elongation.

5. A piezoelectric voltage source according to claim 2, wherein said cam means is longitudinally elongated and extends transverse relative to said frame.

6. A piezoelectric voltage source according to claim 2, wherein said cam means is a generally circular rod having a flat spot and a portion of successively larger diameter extending therefrom on each segment of the periphery facing said second end face and the said other abutment.

7. A piezoelectric voltage source according to claim 5, wherein said frame means includes a relatively flat structural member having a longitudinally extending cut-out for receiving the element means therein.

8. A piezoelectric voltage source according to claim 7, wherein said frame means includes a stationary casing adapted for movably receiving one end of said structural member, the opposite end of said casing being U-shaped and spacedly telescoped over the other end of said structural member.

9. A piezoelectric voltage source according to claim 8, wherein said cam means extends across, through, and is rotatably mounted about said U-shaped portion.

10. A piezoelectric voltage source according to claim 1, wherein rotation of said cam means is effective to move at least portions of said frame means and said element means in opposite directions.

11. A piezoelectric voltage source according to claim 1, wherein rotation of said cam means is elfective to move said element means angularly about the first mentioned abutment.

12. A piezoelectric voltage source according to claim 1, wherein rotation of said cam means is effective to move at least portions of said frame means angularly relative to said element means.

13. A piezoelectric voltage source according to claim 11, wherein the longitudinal axis of said element means is normally angularly offset from the longitudinal axis of said frame means.

14. A piezoelectric voltage source, comprising: frame means having longitudinally spaced abutments rigid against displacement; piezoelectric element means disposed between said abutments and having first and second end faces and a longitudinal axis normal thereto; said first end face being disposed in bearing relation against one of said abutments, said second end face being spaced relative to and facing the other abutment; rolling contact compressing means interposed, in bearing relation, between said second end face and the said other abutment; and actuating means for rotating portions of said compressing means relative to said second end face and the said other abutment to effect relative translation movement substantially perpendicular to said longitudinal axis between said frame means and said element means, to compress the element means in the longitudinal direction against the first named abutment to generate a voltage.

15. A piezoelectric voltage source according to claim 14, wherein said rolling contact compressing means includes a stationary member positioned in bearing relation to the said other abutment, and a rotatable member engaging said stationary member and being positioned in bearing relation to said second end face.

References Cited UNITED STATES PATENTS 3,350,608 10/1967 Maltner 31796 3,262,019 7/1966 Maltner 3108.7 3,211,069 10/1964 Rixton 11.5 3,118,074 1/ 1964 Josephson 3 l0--8.7 3,114,059 12/1963 Hulferd 310-8] 3,082,333 3/1963 Hulferd 3l08.7 3,295,024 12/1966 Newman 3108.7 3,211,949 10/ 1965 Slaymaker 310-8.7 3,101,420 8/ 1963 Hufferd 3 l08.7

FOREIGN PATENTS 712,803 7/ 1954 Great Britain.

J. D. MILLER, Primary Examiner US. Cl. X.R.

Notice of Adverse Decisions in Interferences In Interference No. 97,388 involving Patent No. 3,469,155, H. W. Van Beek, PUNCH-THROUGH MEANS INTEGRATED WITH MOS TYPE DE- VICES F OR PROTECTION AGAINST INSULATION LAYER BREAK- DOWN, final judgment adverse to the patentee was rendered Dec. 29, 1972, as to claims 1-8.

[Official Gazette May 92, 1973.]