US3558903A

US3558903A - Mechanically activated piezoelectric voltage source

Info

Publication number: US3558903A
Application number: US646397A
Authority: US
Inventors: Norihoko Yamano
Original assignee: Rion Co Ltd
Current assignee: Rion Co Ltd
Priority date: 1966-06-25
Filing date: 1967-06-15
Publication date: 1971-01-26
Anticipated expiration: 1988-01-26
Also published as: DE1613866B2; DE1613866A1; DE1613866C3

Abstract

The disclosed devices include a ceramic piezoelectric element pivotable mounted at one end and having a pressure bearing member secured at the other end. A wedge member is disposed above the pressure bearing member to rollably sandwich a roller of circular cross section between both members. When the roller is forcedly rolled in a space formed between both members it will make the piezoelectric element swing about its lower end and consequently squeezes the latter, resulting in the production of high voltage by the element. During returning movement of the roller a high voltage is also produced by the piezoelectric element. The wedge may be spring loaded for the purpose of preventing the roller from loosening from two sandwiching members during service. The roller may have a cross section in the form of a regular polygon such as a regular hexagon embraced between a pair of opposed identical grooves trapezoidal in shape. Also a force may be applied directly to the piezoelectric element to swing, whereby squeezing it through rolling of the associated roller. A completely moisture proof device is also disclosed.

Description

O United States Patent 1 3,558,903

[72] Inventor Norihoko Yamano 3,453,458 7/1969 Curran 310/9.1 Kokubunji, Japan 3,469,119 9/1969 Parkinson 310/8.7 gy s- 3 1967 FOREIGN PATENTS i e une Patented "16, 1971 1,054,103 1/1967 Great Britain 310/8.3 [73] Assignee Rion Kabushiki Kiasha Primary ExaminerMilton O. Hirshfield Tokyo, Japan Assistant Examiner-Mark O. Budd [32] Priority June 25, 1966, July 7, 1966 Alt0rneyWenderoth, Lind & Ponack [33] Japan [31] 41/40968 and 41/64532 ABSTRACT: The disclosed devices include a ceramic piezoelectric element pivotable mounted at one end and hav- [54] MECHANICALLY ACTUATED PIEZOELECTRIC ing a pressure bearing member secured at the other end. A VOLTAGE SOURCE wedge member is disposed above the pressure bearing 1 Claim, 12 Drawing Figs. member to rollably sandwich a roller of circular cross section between both members. When the roller is forcedly rolled in a [52] US. Cl 5535477779, Space formed between both members it will make the [51] lnt.Cl HOlv 7/00 Piezoelecmc element Swing about lower end [50] Field of Search 310/8.3- f squeezes the latter 9 m h producnon of 9"; 317 I79PZ; 3 5/55209PZ; 431/255 high voltage by the element. During returning movement of the roller a high voltage is also produced by the piezoelectric element. The wed e may be sprin loaded for the purpose of [56] References cued preventing the ro er from looserfing from two sandwiching UNITED STATES PATENTS members during service. The roller may have a cross section 3,101,420 8/ 1963 Hufford 3 10/ 8.7 in the form of a regular polygon such as a regular hexagon em- 3,114,059 12/1963 H rd" 3l0/8-7 braced between a pair of opposed identical grooves trape- ,2 1 /1 Ri rl 1 /8] zoidal in shape. Also a force may be applied directly to the 3,295,024 12/1966 Newman 310/8.7 piezoelectric element to swing, whereby squeezing it through 3,354,327 11/1967 Benson 310/9.1 rolling of the associated roller. A completely moisture proof 3,430,080 2/1969 Horan 310/9.1 device is also disclosed.

PATENTEI] JAN26197| sum 1 BF 3 MECHANICALLY ACTUATED PIEZOELECTRIC VOLTAGE SOURCE This invention relates in general to improvements in piezoelectric voltage sources and more particularly to a mechanism for producing a high voltage in each of the processes of applying a squeezing pressure to a piezoelectric element and of releasing the applied pressure from the element.

The conventional type 'of piezoelectric voltage sources are disadvantageous in that a ratio of an external force applied to the source to a pressure exerted on the piezoelectric element involved is relatively high, the operation relatively lacks in nimbleness and the mechanism used is complicated and expensive.

An object of the invention is to provide a new and improved mechanism for applying and releasing a pressure to and from a pressure responsive element which is simple and durable in construction, and nimbly and reliably operative with a relatively low operating force.

Another object of the invention is to provide a new and improved piezoelectric voltage source suitable for use in any igniting equipment or any internal combustion engine for purpose of ignition.

Briefly, the invention accomplishes the above cited objects by providing a piezoelectric voltage source comprising housing means, piezoelectric element means pivotably mounted at one end within the housing and having a pressure bearing flat surface rigidly connected to the other end, the housing means being rigid against expansion in the longitudinal direction of the piezoelectric element means, a rigid block including a flat surface opposite the pressure bearing surface to form a space therebetween, an actuating roller rollably sandwiched between both the opposite surfaces, and means for rolling the actuating roller and swinging the piezoelectric element means about the one end thereby to apply and release a squeezing pressure to and from the piezoelectric element means whereupon a high voltage is produced by the piezoelectric element means respectively.

' Preferably, the rigid block member may be a wedge-shaped member loaded with spring means to always push the roller against the pressure bearing member, in order to prevent the roller from being loosely carried between the associated planes during service.

While the roller may be advantageously of a circular cross section, it may have, if desired, a cross section in the form of a regular polygon having any desired number of sides such as six, seven, or eight sides. Such a polygonal roller may be conveniently embraced within a pair of opposite identical grooves in the form of a regular trapezium and can exert both a squeeze and an impulsive pressure on the associated piezoelectric element means.

Instead of an external force being applied to the roller, such a" force may be advantageously applied directly to the piezoelectric element means to effect swinging movement of the latter accompanied by rolling movement of the associated roller thereby to squeeze the piezoelectric element means.

The invention will become more readily apparent from the following detailed description taken in'conjunction with the accompanying drawings in which:

, FIG. 1 is a front elevational view of a piezoelectric voltage source constructed in accordance with one embodiment of the invention with parts cut away;

FIG. 2 is a sectional view taken along the line IIII of FIG. 1;

FIG. 3 is a fragmental, schematic side elevational view of the source illustrated in FIGS. 1 and 2 useful in explaining the operation of the invention.

J FIG. 4 is a front elevational view, partly in section of a piezoelectric voltage source constructed in accordance with another embodiment of the invention with parts cut away;

FIG. 5 is a sectional view taken along the line V-V of FIG. 4;

FIG. 6 is a fragmental front elevational view in section of another pivotal mounting of a piezoelectric element.

FIG. 7 is a fragmental side elevational view in section' of a modification of FIG. 5;

FIG. 8 is a view similar to FIG. 5 but illustrating another modification of the invention;

FIG. 9 is a side elevational view useful in explaining the operation of the mechanism illustrated in FIG. 8;

FIG. 10 is a side elevational view in section of still another embodiment of the invention; I

FIG/ 11 is a front elevational view of a moistureproof piezoelectric voltage source constructed in .accordance with another embodiment of the invention; and

FIG. 12 is a sectional view taken along the line XII-XII of FIG. 11.

The invention is based on the concept that, in theprocess of rotating an actuating roller movably sandwiched between a pair of opposite planes disposed in tilted relationship to move it in which a space confined by both planes, thus a squeezing pressure is produced in the associated piezoelectric element and also in the process of returning the roller of its original position the applied pressure is released from the piezoelectric element. The invention is characterized in that the piezoelectric element turns or swing about at a pivot at its one end. One of the planes is disposed in fixed relationship with respect to the end face of the element and the planes are tilted to the end element face. Thus the above-mentioned swinging of the element causes the roller to roll up the other plane while at the same time the roller mounts up to the uphill of one plane. This change of in the position of roller relative to both planes applies a high squeezing pressure to the piezoelectric element along its vertical axis, and releases the pressure from the element when the roller is turned in opposite direction. In the case a two piece type piezoelectric element of the conventional construction is used, a high voltage is provided between the central electrode and each of both end terminals each time a squeezing pressure is applied and released to and from the element with the voltage due to the application of the-pressure having a polarity opposite to that due to the release thereof.

Referring now to the drawings and FIGS. 1 and 2 in particular, there is illustrated a piezoelectric voltage source constructed in accordance with one embodiment of the invention. The source generally designated by the reference numeral 10 includes a housing 12 comprising a pair of

housing portions

12a and 12b disposed back-to-back into a substantially V shape. Each

housing portion

12a or 12b is preferably made of sheet steel, channel shaped in cross section, and provided on its central plat portion, with a rectangular opening 14 having a dimension dependent upon the size of a piezoelectric element as will be described hereinafter. The pair of

housing portions

12a and 12 b are connected together at one end or the lower ends as viewed in FIGS. 1 and 2, by a bolt 16 and the associated nut and at the other ends or the upper ends by another bolt 18 and the associated nut with a hollow spacer 20 disposed around the bolt between housing portions. Thus the housing portions are forcedly connected together into a substantially V-shape to form a space therebetween. With the arrangement as above described it will be appreciated that the housing is rigid against longitudinal tensile stress.

Disposed within the space as above described is a piezoelectric crystal element 22 preferably, through not necessarily, comprising a pair of separate pillar shaped elements of any desired

cross section

22a and 22b arranged end-to-end and composed of a polycrystalline ceramic material such as a barium titanate, lead titanate zirconate or the like. As well known, such elements, when squeezed, produce a high voltage and have sufficient storage capacity and internal resistance to hold the charge for a considerable period of time.

The piezoelectric element 22 has an electrode 24 sandwiched between the two

elements

22a and 22b and also a support member 26 and a pressure bearing member 28 secured at its free ends respectively. Both members also serve to act as the other electrode of the piezoelectric element 22. Thus it will be seen that the two

piezoelectric elements

22a and 22b are mechanically in series and electrically in parallel. The piezoelectric element 22 has a covering layer 30 of any suitable electrically insulating material applied to the surface thereof except for those surface portions contacting the pressure bearing and supporting

members

28 and 26 respectively. An electrically insulated cord 32 is electrically connected to the common electrode 24. and projects beyond the central opening of housing portion 12b. The cord 32 is surrounded by an electrically insulating protrusion 34 integral with the insulating layer 30 in order to insure that the cord is held in place and electrically connectedto the electrode 24.

The support member 26 which may be preferably of a special steel is provided on that surface remote from the piezoelectric element 22 with a transverse groove 36 in the form of a segment of a circle whose center lies on the central plane between the

opposed housing portions

12a and 12b. The groove 36 then engages a ridge 38 of complemental shape formed on the connected lower end portions of the housing portions providing the lower edge of the rectangular opening 14 thereby to allow the piezoelectric element 22 to turn or swing about the central line of the groove 36.

The pressure bearing member 28 made, for example, of a special steel and hardened has an upper free flat surface 29 tilted downwardly at a predetermined angle to the transverse axis of the piezoelectric element 22 for the purpose as will be apparent hereinafter. A roller 40 of circular cross section made of a special steel and hardened is disposed on the pres- -"sure bearing surface 29. A wedge-shaped member 42 slidably fixed on the upper portion of the housing 12 engages the upper edge of the rectangular opening I4 and is normally biased in the direction of its reduced end by a leaf spring 44 carried between the folded

sides

46 and 47 of the channel member 12a. The wedge-shaped 42 made preferably of steel and hardened is located at such a position that the roller 40 is resiliently sandwiched between the same and the pressure bearing member 28 for rolling movement as well as forming a space as shown in FIG. 3. The spring loaded wedge member 42 also serves to preventing an actuating mechanism including the pressure bearing member 28, the roller 40 and the wedgeshaped member 42 from loosening clue to wear during a long service.

It is to be noted that, if desired, either the pressure bearing surface 29 or wedge member 42 may not be tilted provided that its opposing surface is tilted to forms the space tapered-as above described.

. The roller 40 includes one end portion projecting beyond the housing 12 and bent substantially perpendicularly to its original direction providing an operating handle 48.

In order to limit the rolling movement of the roller 40, the tilted surface 29 of the pressure bearing member 28 includes ridged end portions 49a and 4%.

As an example, at least one of the upper surface 29 of the pressure bearing member 28 may be preferably tilted downwardly or upwardly to the transverse axis of the piezoelectric element 22, at an angle of from 3 to 6 degrees and the roller 42 has a diameter preferably ranging from 2.5 to 4 mm.

The operation of the piezoelectric .voltage source illustrated in FIGS. 1 and 2 will now be described in conjunction with FIG. 3 wherein the same reference numerals designate the components corresponding to those shown in FIGS. 1 and 2. The piezoelectric elements 22 is normally in its position where its central line 22c tilts toward the left of the central line 12c of the housing 12. Under these circumstances the operating rod 48 can turn in the direction of the arrow a shown in FIG. 3 to force the roller 40 to roll in the direction of the arrow b between the flat surfaces 29 and the opposed flat surface the wedge-shaped member 42 while ascending along the surface 29. This causes the piezoelectric element 12 to turn or swing in the direction of the arrow c to its position illustrated at dot-and-dash line in FIG. 3. In other words, the central line 22c of the piezoelectric element 22 tilts toward the right of the central housing line 120. During this transition the roller 40 is gradually pushed against the element 12 lengthwise thereof to tend to shorten the latter while at the same time it rolls and ascends to the higher portion of the tilted surface 42. This causes a squeezing portion pressure to be applied to the piezoelectric element 22. At the instant the roller 40 has reached the central line 22c of the piezoelectric element it exerts a maximum possible pressure on the element 22 whereupon the roller 40 is arranged to be stopped against the ridged end portion 49a.

Then the operating handle 48 can return back to its original position to return the piezoelectric element 22 to its original position shown at solid line in FIG. 3 while the pressure is allowed to be released from the element 22.

It will be seen that in each of the processes of applying the pressure to the piezoelectric element 22 and of returning the latter to its original position, a change in a compressive strain takes place in the material of the piezoelectric element 22 to provide high voltages of opposed polarities at the go and return across the intermediate electrode 24 and each end of the element and hence each of the pressure bearing and supporting

members

28 and 26 with the polarity of the voltage in the process of applying the pressure to the element reversed from that in the process of returning the latter. The high voltage thus produced may be connected across a spark gap formed between electrodes connected to the electric cord 30 and the opposed electrodes connected to the housing 12, although the spark gap and an electrical connection thereto are not illustrated in FIG. 3. Therefore a spark discharge oc curs across the spark gap and can be utilized to ignite, for example, a pilot gas burner or directly any other gas equipment.

Referring now to FIGS. 4 and 5, there is. illustrated a modification of the invention, wherein a voltage source generally designated by the reference numeral 50 includes a housing 52 composed of a length of any suitable strip material such as steel formed into a substantially rectangular shape with the opposed ends of the strip slightly spaced away from each other and a block 54 of any suitable metallic material for example steel rigidly secured to theinside of the lower or open end housing portion by rivets.

Turnably disposed in the interior of the housing 52 is a piezoelectric element 62 similar to the piezoelectric element 22' and including a central electrode 64 and a support member 66 and a pressure bearing member 68 at respective ends. As shown in FIG. 5, a pair of

thin aluminum plates

56 and 58 are interposed between the both end faces of the piezoelectric element 52 and the supporting and

pressure bearing members

66 and 68 respectively. The

thin plates

56 and 58 establish electrical ground connections for the piezoelectric element 62 and also serve to uniformly distribute compressive forces acting upon end faces of the piezoelectric elements 62a and 62b.

The support member 66 is provided on the free or lower surface with a central recess 76 in the form of a spherical segment pivotably engaging a complemental head 78 of a screw 79 screwed into the block 54. Thus recess 76 and the screw head 78 provide a sphere and socket joint allowing the piezoelectric element 64 to swing about it. Thescrew 79 also serves to compensate for a variation in length of the associated element 62 during the assembling operation.

A roller 80 of the circular cross section extends through a pair of aligned

openings

80 and 81 formed on the opposed portions of the housing 52 and is rollably sandwiched between the pressure bearing member 68 and a wedge-shaped member 82 secured to the upper inner end face of the housing 52. The diameters of the

openings

58 and 81 are selected to limit the rolling movement of the roller 80 and accordingly the

ridged end portions

49a and 49b on the upper bearing surface 29 shown in FIG. 2 are omitted. The wedge-shaped member 82 engaging the roller 80 is normally urged longitudinally in the direction of its reduced end by the action of a leaf spring 84 disposed within the housing 52 and engaging a pair of

pins

86 and 88 planted on the latter. In FIGS. 4 and 5 it is noted that the use of a ball and socket coupling 76-78 serves to effect smooth swinging movement of the piezoelectric element 22 as well as its mechanism itself is robust, leading to increasing the durability.

FIG. 6 wherein the components corresponding a similar to those shown in FIGS. 4 and 5 are designated by the same reference numerals with the prime, illustrates a modification of a pivotal mounting of a piezoelectric element 62. Instead of the screw 79 being used, a metallic block 54 such as the block 54 shown in FIGS. 4 and 5 is provided at the center with a recess complemental in shape to a steel ball 78. This ball is 78' is operatively coupled to a recess 76 complemental in shape to the ball 78' and formed on a support member 66. The coupling just described allows the piezoelectric element 62 to swing in a smoother manner as compared with the arrangement shown in FIGS. 4 and 5.

FIG. 7 wherein the components corresponding or similar to those shown in FIGS. 4 and 5 are designated by like reference numerals primed, illustrates another manner in which a roller is rollably carried on the upper surface of a pressure bearing member. As shown in FIG. 7, a pressure bearing member 68 is provided on the upper surface with a central transverse groove 90 of circularly arcuated cross section whose radius approximates a radius of a roller 80 arranged to engage the groove 90 and whose center lies in the central plane of a piezoelectric element 62 about which the latter is tumable. When the roller 80 has supplied thereto a rotational force, it will be sliding in the groove 90 while rolling relative to both a wedge-shaped member 82 upwardly contacting it and the pressure bearing member 68' fixed to the element 62'. Thereby the associated piezoelectric element 62' is swing and squeezed. w

The arrangement shown in FIG. 7 is characterized in that the roller 80' occupies its position always lying in central plane of the piezoelectric element 62' thereby to apply to the latter a force always directed in that plane resulting in an increase in ratio of conversion of mechanical to electrical ener-.

Referring now to FIGS. 8 and 9 wherein the components corresponding or similar to those shown in FIGS. 4 and 5 are designated by the same reference numerals-primed, a roller 80 for actuating a piezoelectric element 62' is of regular hexagonal cross section. It is to be noted that a regular polygon may have any desired number of sides. For example, it may be seven or eight sided.

A pressure bearing member 68' is provided on its operating surface with a transverse groove 92, in the form of an equal sided trapezoid with its longest side open and with each lateral side having slope conforming to an angle formed between adjacent sides of the polygonal cross section of the roller involved. Instead of the wedge-shaped

member

42 or 82 used in the previous embodiments, a rigid block 82' made for example of a special steel is fixed in one portion, in this case, the upper end portion as viewed inFIG. 8 of a housing 52' and is provided on the lower surface facing the pressure bearing member 68" with a transverse groove 94 identical in shape and in registering and cooperating position with the recess 92 on the pressure bearing member 68'. The roller 80' is rollably embraced in both

recesses

92 and 94. In the other respects the arrangement shown in FIGS. 8 and 9 is substantially similar to that illustrated in FIGS. 4 and 5.

In operation, an operating handle 48 can be manually rotated in the direction of the arrow d from its position designated at solid line or represented by dot-and-dash line A-A to roll the roller 80. This rolling movement of the roller 80' causes the distance between both bottom recess surfaces to progressively increase thereby to apply a high axial force to the piezoelectric element 62' while swinging the latter about its ball and socket joint 76'78. During this rotational movement of the operating handle 48 as reaching the central plane 8-8 of the device (FIG. 9) permits the roller 80' to apply a maximum squeezing force to the piezoelectric element 62' now located in its position as shown in FIG. 8. As soon as the handle 48 has passed through the central plane B-B the resilience of the piezoelectric element 62' causes the handle 48 to be rapidly moved to its position represented by dot-anddash line C-C and substantially symmetrical to its original position with respect to the central plane B-B. This causes the applied squeezing force to be rapidly released from the piezoelectric element 62. Therefore, it may be said that the operating handle 48 is stable when it is on line A-A or C-C whereas it is unstable in its position represented by line B-B.

Thus it will beappreciated that the operating handle 48 is operated'in approximately stepped manner and especially in the process in which the force is released from the piezoelectric element, a rate of decrease in applied pressure with respect to time is large as compared with the roller of circular cross section. This is accompanied by the effect that the operating handle pulses the piezoelectric element while it still squeezes the latter. From the above reasons it will be understood that the arrangement shown in FIGS. 8 and 9 is especially suitable for use in producing repeated spark'dischargcs with a high density.

While the invention has been described in terms of the roller or the associated operating handle being operated means of an external force to squeeze the piezoelectric element, it is to be understood that an external force may be directly applied to the piezoelectric element to squeeze it with satisfactory results. This will be subsequently described in conjunction with FIG. 10.

In FIG. 10 wherein the components corresponding or similar to those shown in FIGS. 4 and 5 are designated by the same reference numerals primed, a housing 52" has pivotably mounted at thereto, a lever 98 provided with an operating nose 102 adapted to abut against one side of a pressure bearing member 68". The lever 98 can be manually pushed in the direction of the arrow e to swing a piezoelectric element 62 about the center of a steel ball 78". This swinging movement of the piezoelectric element 62 causes the roller 80 to roll between the pressure bearing member 68" and a wedgeshaped member 82" to squeeze the piezoelectric element leading to the generation of a high voltage.

As will be appreciated, the present piezoelectric voltage sources may be used in kitchens where it is relatively high in humidity or splashed with water, for the purpose of igniting gas ranges. Under these circumstances it is required to prevent any leakage of a voltage output from the source due to the ambient moisture.

FIGS. 11 and 12 show the moistureproof type of the present device. A housing 52 is in the form of a closed box and has, hermetically sealed therethrough, an electric cord 32 electrically connected to an electrode 64 of a piezoelectric element 62. In order to insure that any moisture is prevented from entering the interior of the box 52 through a clearance between exit of the electric cord and the adjacent portion of the housing a coating 104 of any suitable electrically insulating material is applied to the exit of the cord 32 and extends in the form of a bellows 106 into the housing until it is connected to an electric insulation 30 disposed on the piezoelectric element '62. The bellows type covering 106 can effectively accommodate any lateral displacement of the piezoelectric element 62. Similarly the electric cord 32 is electrically connected to the electrode 64 through a flexible lead 108.

Further a pair of openings, provided on the opposed portions of the housing 52 to limit movement of a roller 80, is provided with closure covers 110 and 1 11 respectively in order to prevent any ingress of moisture therethrough.

In this way the device illustrated in FIGS. 11 and 12 has the completely closed interior and is protected against any deterioration of' electric insulation due to the ingress of moisture as well as providing a dust tight structure. In the other respects the arrangement is similar to that illustrated in FIGS. 4 and 5 and the same reference numerals designate the components corresponding or similar to those illustrated in FIGS. 4 and 5.

The invention has several advantages. For example, the present voltage source can not only be operated with a very low operating force because the piezoelectric element effects swinging movement but also it is extremely effective for generating a continuous multispark by having a high squeezing pressure applied to the piezoelectric element. The use of a spring loaded wedge-shaped member fully compensates for any looseness of the mechanism for applying a squeezing pressure to the piezoelectric element which may take place during service. In addition the invention is extremely simple in construction because of the omission of a bearing associated with the roller or its operating handle.

While the invention has been illustrated and described in conjunction with certain preferred embodiments thereof it is to be understood that numerous changes and modifications may be resorted to without departing from the spirit and scope of the invention. For example, in order to ignite an internal combustion engine, the present voltage source may be operated by any suitable cam mechanism suitably coupled to the rotary shaft of the engine.

lclaim:

l. in a piezoelectric voltage source, the combination of housing means, piezoelectric element means including an elongated ceramic piezoelectric element, a support member secured to one end thereof, a pressure receiving member secured to the other end thereof, and a covering of an electrical insulating material disposed on the surface thereof, said housing means being rigid against expansion in the longitudinal direction of said piezoelectric element means, said support member being in pivotal engagement with said housing means for pivotably supporting said'piezoelectric element means within said housing means, said pressure bearing gaged with said piezoelectric element means to swing said' piezoelectric element means, thereby rolling said actuating roller toward and then away from the smaller end of said wedge-shaped space and thereby to apply and release squeezing pressure to and from said ceramic piezoelectric element, whereupon a high voltage is produced by said piezoelectric element.

Claims

1. IN A PIEZOELECTRIC VOLTAGE SOURCE, THE COMBINATION OF HOUSING MEANS, PIEZOELECTRIC ELEMENT MEANS INCLUDING AN ELONGATED CERAMIC PIEZOELECTRIC ELEMENT, A SUPPORT MEMBER SECURED TO ONE END THEREOF, A PRESSURE RECEIVING MEMBER SECURED TO THE OTHER END THEREOF, AND A COVERING OF AN ELECTRICAL INSULATING MATERIAL DISPOSED ON THE SURFACE THEREOF, SAID HOUSING MEANS BEING RIGID AGAINST EXPANSION IN THE LONGITUDINAL DIRECTION OF SAID PIEZOELECTRIC ELEMENT MEANS, SAID SUPPORT MEMBER BEING IN PIVOTAL ENGAGEMENT WITH SAID HOUSING MEANS FOR PIVOTABLY SUPPORTING SAID PIEZOELECTRIC ELEMENT MEANS WITHIN SAID HOUSING MEANS, SAID PRESSURE BEARING MEMBER INCLUDING A FLAT SURFACE, A WEDGE-SHAPED ABUTMENT MEMBER SLIDABLY MOUNTED WITHIN SAID HOUSING MEANS FOR SLIDING IN A DIRECTION PERPENDICULAR TO THE LONGITUDINAL DIRECTION OF SAID PIEZOELECTRIC ELEMENT MEANS, SAID ABUTMENT MEMBER HAVING AN ABUTMENT SURFACE OPPOSITE SAID FLAT SURFACE AND SPACED FROM SAID FLAT SURFACE SUCH THAT, WITH THE PARTS AT REST IN NONVOLTAGE PRODUCING POSITIONS, A WEDGE-SHAPED SPACE IS FORMED BETWEEN SAID FLAT SURFACE AND THE OPPOSED SURFACE, AN ACTUATING ROLLER HAVING A CIRCULAR CROSS SECTION ROLLABLY SANDWICHED IN SAID WEDGE-SHAPED SPACE, AND A MECHANICAL CAM ENGAGED WITH SAID PIEZOELECTRIC ELEMENT MEANS TO SWING SAID PIEZOELECTRIC ELEMENT MEANS, THEREBY ROLLING SAID ACTUATING ROLLER TOWARD AND THEN AWAY FROM THE SMALLER END OF SAID WEDGE-SHAPED SPACE AND THEREBY TO APPLY AND RELEASE SQUEEZING PRESSURE TO AND FROM SAID CERAMIC PIEZOELECTRIC ELEMENT, WHEREUPON A HIGH VOLTAGE IS PRODUCED BY SAID PIEZOELECTRIC ELEMENT.