CN100587990C - Multilayer piezoelectric element and ejector using same - Google Patents

Abstract

In a laminated piezoelectric element, a plurality of piezoelectric layers and a plurality of metal layers are alternately laminated. The metal layers include a plurality of high resistance metal layers having an electrical resistance higher than electrical resistances of the adjacent metal layers on the both sides. The high resistance metal layers are regularly arranged by sandwiching a pluralityof metal layers other than the high resistance metal layers. In another laminated piezoelectric element, a plurality of piezoelectric layers and a plurality of metal layers are alternately laminated,and at least one layer of the metal layers is composed of a plurality of partial metal layers arranged between the piezoelectric layers.

Description

Piezoelektrisches mehrschichtelement and use the injection apparatus of this Piezoelektrisches mehrschichtelement

Technical field

The present invention relates to Piezoelektrisches mehrschichtelement (following only be called sometimes " element ") and injection apparatus, relate in particular to the Piezoelektrisches mehrschichtelement and the injection apparatus that are applicable to that long-time continuous drives under high voltage/high pressure.

Background technology

All the time, as the device that adopts Piezoelektrisches mehrschichtelement, the piezo actuator that has had piezoelectric body layer and metal level alternately laminated.Piezo actuator generally is divided into two classes, and a class is to fire type simultaneously, another kind of be alternately stacked piezoelectric ceramic that forms by 1 piezoelectrics and plate body metal level pile up type.Wherein, from realizing lower voltage and the viewpoint that reduces manufacturing cost, the piezo actuator of type is fired in employing simultaneously mostly.About firing the piezo actuator of type simultaneously, its thin layer abbreviation list is doing well aspect miniaturization and the durability.

Fig. 6 (a) is a stereogram of representing Piezoelektrisches mehrschichtelement in the past, and Fig. 6 (b) is the part stereogram of the stacked state of piezoelectric body layer in the presentation graphs 6 (a) and metal level.As Fig. 6 (a) with (b), this Piezoelektrisches mehrschichtelement is made of the pair of external electrodes 105 that forms on duplexer 103, the mutual opposed side.Duplexer 103 is alternately laminated piezoelectric body layer 101 and metal level 102.In the both end sides of the stacked direction of duplexer 103, stacked respectively non-active layer 104.Metal level (interior electrode layer) 102 is not formed on whole of the interarea of piezoelectric body layer 101, becomes so-called partial electrode structure.The metal level 102 stacked different sides that are exposed to duplexer 103 every one deck that become of this partial electrode structure are connected with pair of external electrodes 105 respectively every one deck.

As the manufacture method of in the past Piezoelektrisches mehrschichtelement, as described below.Promptly at first, the pattern according to becoming the specified metal layer structure shown in Fig. 6 (b) is printed onto metal cream on the ceramic printed-circuit board of the raw material that contains piezoelectric body layer 101.Then, stacked a plurality of tellites that are printed with metal cream come making layer to build up body, it is fired and obtain duplexer 103.Afterwards, behind the plating cream of the opposed side of duplexer 103, fire and form a pair of outer electrode 105, obtain the Piezoelektrisches mehrschichtelement shown in Fig. 6 (a) (for example with reference to patent documentation 1).

Here, as metal level 102, general most alloy that adopts silver and palladium.In addition, in order to fire piezoelectric body layer 101 and metal level 102 simultaneously, the metal composition of metal level 102 is set at mostly: silver-colored 70 quality %, palladium 30 quality % (for example with reference to patent documentation 2).Only do not adopt the metal level that constitutes by silver like this and adopt the reasons are as follows of metal level 102 that silver-palladium alloy constitutes described.

Promptly, if metal level 102 be do not comprise palladium and have only silver composition, when then between to opposed metal level 102, applying voltage difference, the silver ion in the metal level 102 on opposed metal level 102 from the positive pole to the negative pole, move in the element surface transmission, produce so-called ion transport phenomena.This phenomenon has the tendency of remarkable generation under hot and humid environment.

On the other hand, be purpose to form the roughly the same metal level of metal filled rate 102 in the past, adopt metal ingredient ratio or metal concentration are modulated into roughly the same metal cream.When being screen-printed to this metal cream on the ceramic printed-circuit board, mesh-density or resist thickness setting be made duplexer 103 for identical conditions roughly.

In addition, pushing and during the laminated ceramic tellite, pressed state there are differences in metal level 102 superposed part and non-superposed part, even so in the same one side of metal level 102, it is inhomogeneous that metal level density becomes sometimes.Therefore proposed the method (for example with reference to patent documentation 3) of the following stated: the ceramic strip in the part that forms metal level 120 becomes recess, makes metal filled rate even.

But, when general's Piezoelektrisches mehrschichtelement in the past is used as piezo actuator, lead (not shown) being affixed to outer electrode 105 by scolding tin, the current potential that externally applies regulation between the electrode 105 drives.In addition, in recent years, when requiring the Piezoelektrisches mehrschichtelement miniaturization, also to guarantee addendum modification big under big pressure, thus require to apply higher electric field, and can under the condition of the cruelty that long-time continuous drives, use.

In order to tackle the requirement that long-time continuous drives under high pressure, in patent documentation 4, proposed to be provided with the element of the layer of the varied in thickness that makes piezoelectrics 101 like this.That is, utilize, attempt relaxing stress by making the thickness difference make addendum modification different with other layers.

Following proposal (for example with reference to patent documentation 5) has also been proposed in addition: in piling up the Piezoelektrisches mehrschichtelement of type, if the contact resistance at the interface of metal level and piezoelectric body layer is a high resistance at the central portion of the stacked direction of Piezoelektrisches mehrschichtelement, along with passing to two ends and diminishing, by controlling according to this sample loading mode, stress is not concentrated in the central portion of the stacked direction of Piezoelektrisches mehrschichtelement.

Patent documentation 1: the Japan Patent spy opens clear 61-133715 communique

Patent documentation 2: Japan Patent is opened flat 1-130568 communique in fact

Patent documentation 3: Japanese patent laid-open 10-199750 communique

Patent documentation 4: the Japan Patent spy opens clear 60-86880 communique

Patent documentation 5: Japanese patent laid-open 6-326370 communique

But, in Piezoelektrisches mehrschichtelement in the past, as mentioned above, attempt forming the even metal layer always, apply electric field equably to all piezoelectrics thus.Especially, perhaps even for the conductance that makes each metal level is even for the surface area that makes the part of joining with piezoelectric body layer, and attempt making the metal filled rate of metal level even always.For this reason, follow displacement and the stress that produces concentrates on around the central portion of stacked direction of Piezoelektrisches mehrschichtelement, thereby produce unfavorable conditions such as the crack occur.

As its improvement method, though the method shown in the patent documentation 4,5 is arranged, but mostly under the condition of the cruelty of long-time continuous running under high electric field, the high pressure etc., use now, under such condition, even not talkatively improved fully, the periphery that stress concentrates on the element central portion can take place, produce the crack, perhaps peel off, or the situation of addendum modification variation.

Especially, fire simultaneously in the Piezoelektrisches mehrschichtelement of the affined type of periphery at least a portion of the Piezoelektrisches mehrschichtelement of type or piezoelectrics, the danger that produces the problems referred to above is very high.

In addition, also can take place sometimes to produce sound because of the covibration of the displacement behavior unanimity of each piezoelectric body layer, the high order harmonic component signal that produces the driving frequency integral multiple also becomes noise contribution.

In addition, when in the past Piezoelektrisches mehrschichtelement is used as the actuator that utilizes in the driving element of fuel injection device etc., owing to produce the problem that desirable addendum modification gradually changes, so require the inhibition of variation of addendum modification of long-time continuous running and the raising of durability.

Summary of the invention

For this reason, the present invention puts in view of the above-mentioned problems and makes, and purpose is to provide good Piezoelektrisches mehrschichtelement of a kind of durability and injection apparatus, even it under the situation that high voltage, high pressure long-time continuous drive, also can suppress addendum modification and change.

Other purposes of the present invention are to provide a kind of Piezoelektrisches mehrschichtelement and injection apparatus that can suppress the generating noise that causes because of covibration.

Inventors of the present invention have carried out wholwe-hearted research in order to solve above-mentioned problem.Its result, found high-resistance metal layer by the metal floor height of the adjacent both sides of a plurality of resistance ratios of configuration, even thereby under the long situation of Continuous Drive under high voltage, the high pressure, addendum modification can not change yet, can obtain the outstanding Piezoelektrisches mehrschichtelement of durability, finish the present invention thus.

That is, Piezoelektrisches mehrschichtelement of the present invention, it forms by alternately laminated a plurality of piezoelectric body layers and a plurality of metal level, and a plurality of described metal levels comprise a plurality of high-resistance metal layers, and the resistance of this high-resistance metal layer is higher than the resistance of the metal level of adjacent both sides.

In Piezoelektrisches mehrschichtelement of the present invention, preferred a plurality of described high-resistance metal layers clip a plurality of other metal levels beyond this high-resistance metal layer respectively and dispose.In addition, preferred described high-resistance metal layer disposes regularly.Further preferred its inner voidage of described high-resistance metal layer is greater than the voidage in described other metal levels.Preferred described high-resistance metal layer comprises the high resistance composition of described other metal floor heights of resistance ratio, and the containing ratio of this high resistance composition is than the containing ratio height of the high resistance composition in described other metal levels.In addition, the thickness of preferred described high-resistance metal layer is thinner than described other metal levels.The resistance of preferred described high-resistance metal layer is 1/10～1000 times of resistance of described piezoelectric body layer, and the resistance that is more preferably described high-resistance metal layer is more than 1000 times of resistance of other metal levels of these adjacent both sides of high-resistance metal layer.

Other Piezoelektrisches mehrschichtelements of the present invention form by alternately laminated a plurality of piezoelectric body layers and a plurality of metal level, and the one deck at least in described a plurality of metal levels is made of a plurality of part metals layers that are disposed between described piezoelectric body layer.

The part of preferred described a plurality of part metals layers, piezoelectric body layer in the two ends of the thickness direction of this part metals layer and adjacent both sides joins, the remainder of described a plurality of part metals layers, only an end and the piezoelectric body layer at the thickness direction of this part metals layer joins.

In addition, preferably have a plurality of metal levels that are made of described part metals layer, a plurality of metal levels that are made of described part metals layer dispose across a plurality of piezoelectric body layers respectively in addition.Preferably a plurality of metal levels that are made of described part metals layer dispose regularly.In addition, preferred described part metals layer, along with the approaching piezoelectric body layer that joins with the metal level that is made of this part metals layer, width reduces gradually or increases gradually.Preferred described part metals layer is made of the alloy of silver or palladium or silver and palladium.Further preferably between adjacent described part metals layer, there is the gap.In addition, preferably in the side of described duplexer, form the pair of external electrodes that is connected with described a plurality of metal levels.

Injection apparatus of the present invention comprises container and above-mentioned Piezoelektrisches mehrschichtelement with squit hole, and the driving by described Piezoelektrisches mehrschichtelement sprays the liquid of filling in the described container from described spray-hole.

According to Piezoelektrisches mehrschichtelement of the present invention, because a plurality of described metal levels comprise that resistance is higher than a plurality of high-resistance metal layers of the metal level of adjacent both sides, so the displacement of the piezoelectric body layer that joins with the high-resistance metal layer diminishes.Owing in Piezoelektrisches mehrschichtelement, have the little a plurality of piezoelectric body layers of such displacement,,, further develop even the generation crack also can suppress it so can suppress to produce the crack so the distribution of the stress that produces because of displacement is disperseed.Thus, even under the situation that long-time continuous under high voltage, the high pressure drives, also can suppress addendum modification and change, so the Piezoelektrisches mehrschichtelement that durability is outstanding and reliability is high can be provided.

According to other Piezoelektrisches mehrschichtelements of the present invention, because the one deck at least in a plurality of metal levels is made of a plurality of part metals layers that are configured between piezoelectric body layer, so the stress that the metal level that is made of this part metals layer produces because of its displacement can the displacement of absorption pressure electrics layer the time.In addition, owing to have the metal level that constitutes by this part metals layer, thus the degree of freedom of the piezoelectric body layer of this metal level periphery is big, so can increase the displacement of these piezoelectric body layers.Thus, can relax the compressing of the deformed element of extending stress band, the stress that the suppression element distortion brings is concentrated, so obtain big addendum modification, suppress covibration, even under the situation that long-time continuous under high voltage, the high pressure drives, also can suppress addendum modification and change, obtain the outstanding Piezoelektrisches mehrschichtelement of durability.

Piezoelektrisches mehrschichtelement of the present invention is not even addendum modification can substantially change yet under the situation of Continuous Drive, so the injection apparatus that durability is outstanding and reliability is high can be provided.

Description of drawings

Fig. 1 (a) is the stereogram of the related Piezoelektrisches mehrschichtelement of expression an embodiment of the present invention, (b) is the part stereogram of the stacked state of piezoelectric body layer in (a) and metal level.

Fig. 2 is the cutaway view of the lit-par-lit structure of the related Piezoelektrisches mehrschichtelement of expression first execution mode.

Fig. 3 (a) is the stereogram of the related Piezoelektrisches mehrschichtelement of expression other execution modes of the present invention, (b) is the part stereogram of the stacked state of piezoelectric body layer in (a) and metal level.

Fig. 4 (a)～(e) is the amplification view after the periphery of the part metals layer that will dispose between piezoelectric body layer amplifies.

Fig. 5 is the general profile chart of the related injection apparatus of expression one embodiment of the present invention.

Fig. 6 (a) is a stereogram of representing Piezoelektrisches mehrschichtelement in the past, (b) is the part stereogram of the stacked state of piezoelectric body layer in (a) and metal level.

Embodiment

＜Piezoelektrisches mehrschichtelement 〉

(first execution mode)

With reference to accompanying drawing the related Piezoelektrisches mehrschichtelement of one embodiment of the present invention is elaborated.Fig. 1 (a) is the stereogram of the related Piezoelektrisches mehrschichtelement of expression present embodiment, and Fig. 1 (b) is the part stereogram of the stacked state of piezoelectric body layer in this Piezoelektrisches mehrschichtelement of expression and metal level.Fig. 2 is the cutaway view of lit-par-lit structure of the metal level that joins with the duplexer layer of the related Piezoelektrisches mehrschichtelement of first execution mode.

As shown in Figure 1, this Piezoelektrisches mehrschichtelement has the duplexer 13 that alternately laminated piezoelectric body layer 11 and metal level 12 form, and joint has pair of external electrodes 15 respectively, and this outer electrode 15 conducts with the end of the metal level 12 that exposes in the opposed side of this duplexer layer 13.The stacked non-active layer 14 that forms by piezoelectric body layer 11 in two ends at the stacked direction of duplexer 13.

Be used as at Piezoelektrisches mehrschichtelement under the situation of piezo actuator, lead (not shown) be affixed to outer electrode 15, as long as this lead is connected with external voltage supply unit (not shown) by scolding tin with present embodiment.Between piezoelectric body layer 11, is furnished with metal level 12, but because this metal level 12 is formed by the metal material of silver-palladium etc., so apply assigned voltage through metal level 12 to each piezoelectric body layer 11, have the effect that piezoelectric body layer 11 is occurred based on the displacement of contrary piezoelectric effect.

Non-active layer 14 is made of the duplexer of stacked a plurality of piezoelectric body layers, because only at an interarea side configuration metal level 12, so also do not produce displacement even apply voltage.

In the Piezoelektrisches mehrschichtelement of present embodiment, as shown in Figure 2, a plurality of metal levels 12 comprise a plurality of high-resistance metal layer 12A of the metal floor height of the both sides that resistance ratio is adjacent, and these high-resistance metal layers 12A clips other metal levels 12B beyond this high-resistance metal layer of multilayer 12A and dispose.That is, a plurality of metal levels 12 are made of a plurality of metal level 12B and the high a plurality of high-resistance metal layer 12A of this metal level of resistance ratio 12B.

In Piezoelektrisches mehrschichtelement in the past, owing to forming roughly even metal layer 12 in order to apply electric field equably to all piezoelectric body layers 11, so element self produces continuous change in size when driving, so all piezoelectrics 11 connect airtight and drive across metal level 12.Therefore, Piezoelektrisches mehrschichtelement drives distortion as one.Therefore, when expansion when compression, stretching, extension, the periphery of the element central portion that attenuates in the centre, because of the stress that the distortion of element produces is concentrated, under the situation that high electric field, high pressure long-time continuous drive, laminated portions (interface of piezoelectric body layer and metal level) occurs and peel off, perhaps produce problem of cracks.

As described in present embodiment, by disposing a plurality of high-resistance metal layer 12A, thereby can disperse the stress that produces because of displacement.Therefore,, dwindle the variation of addendum modification, improve durability even under the situation that high electric field, high pressure long-time continuous drive, also can suppress the generation in crack.

If further be elaborated, with the piezoelectric body layer 11 that high-resistance metal layer 12A joins, its addendum modification ratio is little with the piezoelectric body layer 11 that other metal levels 12B joins.That is, there is the little piezoelectric body layer of a plurality of displacements 11.Therefore, element can one not drive distortion, and becomes the state that a plurality of zones of dividing by high-resistance metal layer 12A drive distortion respectively.Thus, in the element of stress that the element central portion is concentrated, be distributed in each of a plurality of zones, so even under high electric field, high pressure, also can obtain excellent durability in present embodiment in the past.In addition, peel off or produce under the situation in crack, also can suppress the development in crack by the part of the little piezoelectrics 11 of displacement even produce the laminated portions part.Based on above reason, infer the durability that can be improved, and the high element of reliability.

In addition, the quantity of high-resistance metal layer 12A is many more, and stress is overstepping the bounds of propriety to loose, and durability further improves, but if quantity is too much, and the tendency that then has addendum modification to reduce is so preferred amount is at the sum of the piezoelectric body layer 11 of integral body below 20%.

In addition, preferred high-resistance metal layer 12A rule configuration on the stacked direction of Piezoelektrisches mehrschichtelement.Comprise a plurality of other metal levels 12B between high-resistance metal layer 12A and high-resistance metal layer 12A, a plurality of high-resistance metal layer 12A are the rule configuration on stacked direction.Thus, the stress of following displacement to produce is evenly dispersed in respectively on the part of being cut apart by high-resistance metal layer 12A.By in a planned way carrying out the dispersion of stress like this, thereby can suppress the generation in crack, the variation of the addendum modification when suppressing running improves durability.

Here, " configuration of high-resistance metal layer rule " is meant, the number of plies of other metal levels 12B that exists between high- resistance metal layer 12A, 12A is in all identical situation between high-resistance metal layer 12A, the 12A arbitrarily, and it is approximate to making stress situation of homodisperse degree roughly on stacked direction to be also included within the number of plies of other metal levels 12B that exists between high-resistance metal layer 12A, the 12A certainly.Particularly, the number of plies of other metal levels 12B that exists between high-resistance metal layer 12A preferably each number of plies mean value ± 20% scope in, more preferably each number of plies mean value ± 10% scope in, further preferably identical between all high- resistance metal layer 12A, 12A.

The internal voids rate of above-mentioned high-resistance metal layer 12A is 1.5～30 times of voidage of other metal levels 12B, is preferably 5～20 times of voidage of metal level 12B.Thus, the addendum modification of the piezoelectric body layer 11 that joins than two interareas and other metal levels 12B of the addendum modification of the piezoelectric body layer 11 that joins with high-resistance metal layer 12A is little.Zone by little piezoelectric body layer 11 divisions of this addendum modification is littler than the addendum modification of Piezoelektrisches mehrschichtelement integral body, can be suppressed at the crack of the periphery generation of Piezoelektrisches mehrschichtelement, improves durability.In addition, can absorb stress by increasing voidage, so further improved durability.

The voidage of high-resistance metal layer 12A is 40%～99%, more preferably 50%～90%.If voidage less than 40%, then might cause the resistance of metal level not high, the addendum modification of the piezoelectric body layer 11 that joins with it is diminished.On the other hand, if voidage greater than 99%, then might cause the intensity of high-resistance metal layer 12 to reduce, destroy high-resistance metal layer 12A easily.

Here, voidage is by measuring with the face that is parallel to stacked direction or perpendicular to the cross section that the face of stacked direction cuts off Piezoelektrisches mehrschichtelement.By in the cross section of high-resistance metal layer 12A, measure the sectional area in space, with the sectional area of measured area, be converted into percentage then and try to achieve divided by high-resistance metal layer 12A.The diameter in space is not particularly limited, but is preferably 3～100 μ m, more preferably 5～70 μ m.

The method of measuring voidage is divided into two kinds of the following stated.First method is the method for observing the cross section when blocking duplexer 13 with the face that is parallel to stacked direction, and second method is the method in the cross section when observing the face of using perpendicular to stacked direction and blocking duplexer 13.Which kind of method is voidage among the present invention select for use measure can.

When measuring voidage, for example followingly get final product like that with first method.At first, utilize known grinding mechanism milled processed duplexer 13, make the cross section that is parallel to stacked direction expose.Particularly, the table that for example can adopt ケ メ Star ト ジ ヤ パ Application (KEMET JAPAN) joint-stock company to make is gone up grinder KEMET-V-300 as lapping device, grinds by diamond paste.For example wait and observe the cross section of exposing by this milled processed by scanning electron microscope (SEM), light microscope, metallurgical microscopes, light microscope, obtain cross-sectional image, by this cross-sectional image is carried out image processing, measure the voidage of metal level thus.If illustrate, image to the metal level taken by light microscope, apply the gap with black, with the part outside the white coating space, try to achieve the ratio of black part, i.e. (black part area)/(area of the area+white portion of black part) by representing with percentage, thereby can be calculated voidage.For example, under cross-sectional image is colored situation, also can be transformed to gray scale and be divided into black part and white portion.At this moment, set at needs under the situation of the threshold value be used to be divided into white portion and the two-part border of black part, as long as carry out binaryzation by image processing software or the visual threshold value of setting the border.

When measuring voidage, for example followingly get final product like that with second method.At first, utilize known lapping device to grind, till expose in the cross section (perpendicular to the cross section of stacked direction) of the metal level of wanting to measure voidage at the stacked direction of duplexer 13.Particularly, the table that for example can adopt ケ メ Star ト ジ ヤ パ Application (share) company to make is gone up grinder KEMET-V-300 as lapping device, grinds by diamond paste.For example wait and observe the cross section of exposing by this milled processed by scanning electron microscope (SEM), light microscope, metallurgical microscopes, light microscope, obtain cross-sectional image, by this cross-sectional image is carried out image processing, measure the voidage of metal level thus.Particularly, image to the metal level taken by light microscope, apply the gap with black, with the part outside the white coating space, try to achieve the ratio of black part, i.e. (black part area)/(area of the area+white portion of black part) by representing with percentage, thereby can be calculated voidage.For example, under cross-sectional image is colored situation, also can be transformed to gray scale and be divided into black part and white portion.At this moment, set at needs under the situation of the threshold value be used to be divided into white portion and the two-part border of black part, as long as carry out binaryzation by image processing software or the visual threshold value of setting the border.

In addition, when observing the cross section of metal level, preferably be ground to about 1/2 position of metal layer thickness, observe the cross section of exposing thus.Wherein, thin in metal layer thickness, and under the bigger situation of the deviation of thickness, the situation that existence can not expose the cross section integral body of metal level by milled processed.Under these circumstances, in milled processed to moment that the part of metal level is exposed, after observing this exposed portions serve and obtaining cross-sectional image, further to grind, repeated multiple times is carried out operation that other parts except observed part are observed.To make up by the observation image addition that such multi-pass operation obtains, thus the cross section integral body that can observe metal level.

In addition, high-resistance metal layer 12A preferably comprises the high resistance composition that more resistance is high than other metal levels 12B.Particularly, the containing ratio of high resistance composition is 1.5 times～20 times of containing ratio of the high resistance composition among other metal levels 12B, is preferably 2～10 times.By in high-resistance metal layer 12A, adding the high resistance composition so morely, thereby, also can form the high metal level of resistance even the quality entity in space ground reduces.Even dispose the high-resistance metal layer 12A of a plurality of such formation, also can further reduce the variable quantity of displacement.

As the high resistance composition, for example enumerate Pd, Pt, Cr, Ni, Mo, W etc.The particle diameter of high resistance composition is not particularly limited, but is preferably 0.1～100 μ m, more preferably 0.1～50 μ m.

The containing ratio of the high resistance composition among the high-resistance metal layer 12A is preferably 40%～99%, and more preferably 50%～90%.In addition, the containing ratio of high resistance composition can by shooting be parallel to the face of high-resistance metal layer 12A the SEM photo, measure high resistance composition in this face area, and be converted into percentage with measured area then divided by the area of shooting face integral body and try to achieve.

In addition, the thickness of high-resistance metal layer 12A is preferably than the thin thickness of other metal levels 12B.Thickness by making high-resistance metal layer 12A is than the thin thickness of other metal levels 12B, thereby high-resistance metal layer 12A can alleviate the stress that piezoelectric body layer 11 places adjacent with the high-resistance metal layer produce than other metal levels 12B easy deformation more, can improve durability.In addition, when the thickness that makes the high-resistance metal layer is thinner than other metal levels,, be difficult to peel off, so improved durability because the metal level easy deformation absorbs stress.

The thickness of metal level 12A, 12B is measured by the face that blocks Piezoelektrisches mehrschichtelement at stacked direction.Select the position, any 5 place of other metal level 12B, measure thickness with two parallel lines clampings arbitrarily.That is, of two parallel lines is located in the border of metal level and piezoelectric body layer, makes other single line move to another border, measure the distance between two parallel lines.High-resistance metal layer 12A also measures the decision metal layer thickness by same method.The thickness of high-resistance metal layer 12A is not particularly limited, but is preferably 30～0.1 μ m, more preferably 20～1 μ m.In addition, the thickness of other metal levels 12B is more than 103% of high-resistance metal layer preferably, more preferably more than 110%.As the system of selection of the position, 5 place of measuring metal layer thickness, method for example as described below.That is, on the cross section of blocking Piezoelektrisches mehrschichtelement on the stacked direction, select by 1/2 position of the two ends of the cross direction of metal level, cross direction, the position, 5 place that on cross direction, constitutes apart from the position (2 points) of end 1/4.

In addition, in the present invention, high-resistance metal layer 12A is preferably 1/10～1000 times with respect to the resistance ratio of piezoelectric body layer 11.By adopting such scope, thereby can suitably control the addendum modification of the piezoelectric body layer 11 that joins with high-resistance metal layer 12A.By make high-resistance metal layer 12A with respect to the resistance ratio of piezoelectric body layer 11 more than 1/10 times, thereby the addendum modification of the piezoelectric body layer 11 that joins with high-resistance metal layer 12A can fully obtain the effect that stress disperses less than the addendum modification of other piezoelectric body layers 11.In addition, by make high-resistance metal layer 12A with respect to the resistance ratio of piezoelectric body layer 11 below 1000 times, thereby the addendum modification that can prevent the piezoelectric body layer 11 that joins with high-resistance metal layer 12A is too small, prevents stress concentrations.High-resistance metal layer 12A is with respect to more preferably 1～1000 times of the resistance ratio of piezoelectric body layer 11.

In addition, the resistance among the present invention (Ω) can be by in each layer, and the two ends that probe is abutted to the two ends of high-resistance metal layer 12A or piezoelectric body layer 11 adopt picoampire measuring appliance (for example the 4140B of Hewlett-Packard's manufacturing etc.) to measure.Here, " two ends of high-resistance metal layer 12A " are meant the two ends of the high-resistance metal layer 12A that expose opposed two sides (not forming the part of outer electrode 15,15) in duplexer 13.Under situation in the side of duplexer 13 is not exposed in the end of high-resistance metal layer 12A, as long as till expose the end that utilizes known lapping device etc. to be ground to high-resistance metal layer 12A.Then, respectively the probe of picoampire measuring appliance is abutted to two of high-resistance metal layer 12A and bring in measuring resistance.Temperature when measuring the resistance of this moment is preferably 25 ℃.

In addition, the resistance of high-resistance metal layer 12A is preferably at more than 1000 times of resistance of other metal levels 12B.The addendum modification of the piezoelectric body layer 11 that joins with high-resistance metal layer 12A is divided Piezoelektrisches mehrschichtelement less than the piezoelectric body layer 11 that joins with other metal levels 12B by high-resistance metal layer 12A thus, and dispersive stress improves durability.

Then, the method for making to the Piezoelektrisches mehrschichtelement of present embodiment describes.

At first, mix by PbZrO ₃-PbTiO ₃The adhesive that constitutes Deng the calcined powder of the piezoelectric ceramic of the perofskite type oxide that constitutes, by the organic polymer of acrylic compounds and butyral class etc., the plasticizer of DBP (repefral), DOP (dioctyl phthalate) etc., and make slurry, make by the known banded method of forming of scraping the skill in using a kitchen knife in cookery or calender bwol method etc. making this slurry become the ceramic printed-circuit board of piezoelectrics 11.

Then, in the metal dust of the formation high-resistance metal layer 12A of silver-palladium etc., be adhesively fixed when containing drying, the organic substance (for example acrylic particles etc.) of volatilization when firing, add mixed adhesive and plasticizer etc. and make conductive paste, this conductive paste is printed on the upper surface of the tellite of a part in the above-mentioned tellite with the thickness of 1～40 μ m by silk screen printing etc.

By changing the ratio of acrylic particles and metal dust, the voidage of high-resistance metal layer is changed.That is, under the many situations of acrylic particles, the voidage height, under the few situation of acrylic particles, voidage is low.The diameter in space can be adjusted by the diameter that changes particle.

As other printing process, the organic substance of interpolation and mixing acrylic particles etc. is made acrylic particles cream in adhesive and plasticizer etc., on the other hand, in metal dusts such as silver-palladium, add and mixed adhesive and plasticizer wait and make conductive paste, by upper surface layer double exposure brush acrylic particles cream and the conductive paste at the tellite of an above-mentioned part such as silk screen printing.By this printing process, can carry out the more excellent printing of production.

In addition, carry out heat treated, make surface oxidation for the time being, thereby control the voidage of high-resistance metal layer 12A easily by prior metal level to above-mentioned silver-palladium etc.In addition, in the metal level of above-mentioned silver-palladium etc., also can add PZT, lead titanates, the contour resistance components of aluminium.

On the remaining tellite beyond the tellite that forms high-resistance metal layer 12A, be used to form the conductive paste of other metal levels 12B by printings such as silk screen printings.In this conductive paste, also can add the organic substance or the high resistance composition of acrylic particles etc. as required.

Then, stacked a plurality of each tellite that is printed with conductive paste obtains duplexer.Carrying out with the temperature of regulation under the state that weight is placed on this duplexer after the unsticking mixture handles, producing the space among the high-resistance metal layer 12A and do not place weight and fire with 900～1200 ℃, making duplexer 13 thus in order to make.

At this moment, in the tellite of the part of non-active layer 14, the metal dust of the formation metal level 12 of interpolation silver-palladium etc., or during the tellite of the part of stacked non-active layer 14, metal dust by formation metal levels 12 such as printed silver-palladiums on tellite and the slurry that constitutes by inorganic compound and adhesive and plasticizer, thereby contraction behavior and shrinkage in the time of making the sintering of non-active layer 14 and other parts are consistent, so can form fine and close duplexer 13.

In addition, duplexer 13 is not limited to make by above-mentioned method for making, and the duplexer 13 that constitutes as long as can make alternately laminated a plurality of piezoelectrics 11 and a plurality of metal level 12 also can form by other method for makings.

Afterwards, alternately form the metal level 12 that does not expose the metal level 12 that exposes in the side of Piezoelektrisches mehrschichtelement the end and end, the piezoelectrics that metal level 12 that does not expose in the end and outer electrode are 15 partly form groove, in this groove, form the insulator that Young's modulus is lower than the resin of piezoelectrics 11 or rubber etc.Here, described groove is formed on the side of duplexer 13 by inner cutter sweep etc.

Then, in glass powder, add adhesive and make silver-colored glass conductive paste, and it is configured as sheet, the living density of the sheet that (solvent dispersed) after the drying is controlled at 6～9g/cm ³The outer electrode that this sheet is copied to column duplexer 13 forms face, with than the firing temperature of following temperature of the high temperature of the softening point of glass and silver point (965 ℃) and duplexer 13 (℃) the temperature below 4/5 cure, utilize the disappearance of dispersing of adhesive ingredients in the sheet that silver-colored glass conductive paste makes, can form the formed outer electrode 15 of porous matter electric conductor that is three-dimensional mesh configuration.

At this moment, can cure after the cream that will constitute outer electrode 15 is layered on the sheet of multilayer, can be that unit is stacked with each layer also cures, if but cure together at the sheet upper strata of multilayer poststack and more to help production.Changing by every layer under the situation of glass ingredient, though as long as adopt the method that changes the amount of glass ingredient by every layer, but near the face of piezoelectrics 11 constitute as thin as a wafer be rich in the layer of glass the time, employing has been printed on the basis of the cream that is rich in glass the method for the sheet of stacked multilayer by the method for silk screen printing etc. on duplexer 13.At this moment, also can replace printing and adopt sheet below the 5 μ m.

In addition, from effective formation neck (part that attenuates of crystal grain), make silver and metal level 12 diffusion bond in the silver-colored glass conductive paste, space in effective in addition residual outer electrode 15, the viewpoint of the duplexer 13 lateral parts joint of outer electrode 15 and column is set out, and the stoving temperature of described silver-colored glass conductive paste is preferably 500～800 ℃.In addition, the softening point of the glass ingredient in the silver-colored glass conductive paste is preferably 500～800 ℃.If there is neck, then can not become the sintered body of excessive densification, can form the cancellous structure that there is the gap in appropriateness.

Be higher than at stoving temperature under 800 ℃ the situation, the sintering of the silver powder of silver glass conductive paste excessively makes progress, can not form the porous matter electric conductor of effective three-dimensional mesh configuration, cause outer electrode 15 too fine and close, the result causes the Young's modulus of outer electrode 15 too high, can not fully absorb the stress when driving, have the possibility of outer electrode 15 broken strings.Preferably cure with interior temperature with 1.2 times of the softening points of glass.

On the other hand, be lower than when stoving temperature under 500 ℃ the situation,, cause might be when driving causing spark between metal level 12 and the outer electrode 15 because abundant diffusion bond between metal level 12 ends and the outer electrode 15 can not form neck.

Then, the duplexer 13 that will be formed with outer electrode 15 is immersed in the silica gel solution, simultaneously silica gel solution is carried out vacuum degassing, thus at the inner filling gel of the groove of duplexer 13, from silica gel solution, pull out duplexer 13 afterwards, silica gel is covered the side of duplexer 13.Afterwards, be filled in the described silica gel curing that groove is inner and cover the side of duplexer 13 by making, thereby finish Piezoelektrisches mehrschichtelement of the present invention.

Then, lead is connected with outer electrode 15, apply the direct voltage of 0.1～3kV/mm to pair of external electrodes 15 by this lead, by processing that duplexer 13 is polarized, thereby finish the piezo actuator that has utilized Piezoelektrisches mehrschichtelement of the present invention, if the voltage supply unit of lead with the outside is connected, apply voltage via lead and outer electrode 15 to metal level 12, then big displacement takes place because of inverse piezoelectric effect in each piezoelectrics 11, and the automobile fuel injection valve that for example can be used as thus to the engine spray fueling plays a role.

The outer surface of electrode 15 externally also can form the conductivity accessory that is made of conductive adhesive of having buried wire netting or netted metallic plate underground.At this moment, by the outer surface of electrode 15 externally the conductivity accessory is set, even thereby actuator is being inserted big electric current and is making under the situation of its driving with high speed, also can in the conductivity accessory, flow through big electric current, can reduce the electric current that flows through outer electrode 15, therefore can prevent to cause outer electrode 15 local pyrexias and produce broken string, can significantly improve durability.In addition, owing in conductive adhesive, buried the net of metal or netted metallic plate underground, produce be full of cracks so can prevent described conductive adhesive.The net of metal is meant and has enrolled that metal wire forms that netted metallic plate is meant to form the hole and do on metallic plate and reticulates.

In addition, the conductive adhesive that constitutes described conductivity accessory preferably is made of the polyimide resin that has disperseed silver powder.That is, by disperseing the low silver powder of resistivity in the high polyimide resin of thermal endurance, thereby even when at high temperature using, it is low and keep the conductivity accessory of high-adhesive-strength also to form resistance value.

Further preferably, described electroconductive particle is preferably laminar or aspheric particle such as needle-like.This be because, by making aspheric particle such as the laminar or needle-like of being shaped as of electroconductive particle, thereby can strengthen the complexing between this electroconductive particle, can further improve the shear strength of this conductive adhesive.

(second execution mode)

The related Piezoelektrisches mehrschichtelement of second execution mode of the present invention is elaborated.Fig. 3 (a) is the stereogram of the related Piezoelektrisches mehrschichtelement of expression present embodiment, and Fig. 3 (b) is the part stereogram of the stacked state of piezoelectric body layer among Fig. 3 (a) and metal level.

Shown in Fig. 3 (a) and (b), the Piezoelektrisches mehrschichtelement of present embodiment has the duplexer 23 that alternately laminated a plurality of piezoelectric body layer 21 and a plurality of metal level 22a, 22b (below be referred to as " metal level 22 ") form, and is furnished with pair of external electrodes 25 (outer electrode is not shown) on the opposed side of this duplexer 23.The interarea that each metal level 22 is not formed on piezoelectric body layer 21 promptly constitutes so-called partial electrode structure on the whole.A plurality of metal levels 22 of this partial electrode structure are configured to expose opposed side at duplexer 23 respectively every one deck.Thus, metal level 22 is electrically connected with pair of external electrodes 25 every one deck.

In addition, the stacked non-active layer 24 that forms by piezoelectrics of the both end sides of the stacked direction of duplexer 23.Using under the situation of this Piezoelektrisches mehrschichtelement as piezo actuator, by welding lead is affixed to pair of external electrodes 25, and connects the line to the external voltage supply unit and get final product.By applying the voltage of regulation from this external voltage supply unit by lead between adjacent metal layer 22, thereby each piezoelectric body layer 21 is because of the inverse piezoelectric effect displacement.On the other hand, because non-active layer 24 does not dispose metal level 22 in other interarea sides, so do not produce displacement even apply voltage only at an interarea side configuration metal level 22 yet.

The Piezoelektrisches mehrschichtelement of present embodiment, shown in Fig. 3 (a) and (b), the one deck at least in a plurality of metal levels 22 is the metal level 22b that is made of a plurality of part metals layer 22c that are configured in 21 of piezoelectric body layers.Since there be 1 layer of such metal level 22b at least, thus the displacement of Piezoelektrisches mehrschichtelement integral body can not only be increased, and can improve the durability of Piezoelektrisches mehrschichtelement.

That is, as Piezoelektrisches mehrschichtelement in the past, if evenly apply electric field and make whole metal levels be roughly layer uniformly to all piezoelectrics, then when driving, cause that element self size changes continuously.Therefore, all piezoelectrics connect airtight and drive across metal level.Therefore, Piezoelektrisches mehrschichtelement drives distortion as one.Therefore, in when compression expansion, when stretching, the periphery of the element central portion that attenuates in the centre is because of the stress that the distortion of element produces is concentrated.Especially, exist stress to concentrate on the tendency of intersection of the non-active layer of the active layer of piezoelectricity displacement and piezoelectricity invariant position.In addition, also can take place to produce sound, produce the high order harmonic component signal of driving frequency integral multiple and become the problem of noise contribution because of the covibration of the displacement behavior unanimity of each piezoelectric body layer.

To this, in the related Piezoelektrisches mehrschichtelement of present embodiment, by the one deck at least that makes metal level 22 is metal level 22b, thereby the piezoelectric body layer displacement of metal level 22b periphery is little, piezoelectric body layer 21 displacements of metal level 22a periphery are big, and position and the little position of displacement that displacement is big in the element disperseed.By such metal level is configured in the element, thereby can disperse to impose on the stress of element.Thus, concentrate the deformed element that causes by relaxing by stress, thus the displacement that can increase element integral body.In addition, can suppress the stress that the distortion because of element causes and concentrate, even under the situation that long-time continuous under high electric field, the high pressure drives, the also durability that can play very well.

In addition, a plurality of part metals layer 22c of formation metal level 22b preferably roughly are configured between the piezoelectric body layer 21,21 equably.A plurality of part metals layer 22c are configured to mutual interval roughly evenly the time between piezoelectric body layer 21,21, follow the stress of deformed element not to be concentrated in a part, metal level 22b spreads all over the whole zone of element cross-section and plays a role as the stress relaxation layer of piezoelectric body layer.

In the present embodiment shown in Fig. 3 (a) and (b), in duplexer 23, there are a plurality of metal level 22b.Each metal level 22b is across a plurality of piezoelectric body layers 21 and a plurality of metal level 22a configuration, and configuration regularly on the thickness direction of duplexer 23.

The layer that the layer of driving distortion is clipped by metal level 22a in a plurality of piezoelectric body layers 21, so the position across many pieces of piezoelectrics 21 forms metal level 22b in metal level 22, can be to guarantee the addendum modification of element to a certain degree.In addition, owing to the change in size of energy suppression element, the covibration that produces when being the concentrated unanimity of displacement, so can prevent the sound generation.And then, owing to can prevent the generation of high order harmonic component signal, so can suppress the noise of control signal.In addition, by making the varied in thickness of metal level 22, thereby can suppress the size of the displacement of piezoelectrics 11,, just can realize production is effectively constructed so do not need to change the thickness of piezoelectrics 21.

In addition, in the present invention, the part of a plurality of part metals layer 22c, with the thickness direction two ends of this part metals layer 22c the piezoelectric layer 21 of adjacent both sides join (Fig. 4 (a)) the surplus quality award from the ministry choosing that constitutes a plurality of part metals layer 22c of metal level 22b only should join (Fig. 4 (b)) at an end and piezoelectric body layer 21 of the thickness direction of part metals layer 22c.In addition, also can be that distolateral roughly whole of part metals layer 22c such shown in Fig. 4 (c) joined with piezoelectric body layer 21, the state that another distolateral only part and piezoelectric body layer 21 join.One of function that metal level 22b is required is that the displacement when Piezoelektrisches mehrschichtelement is driven increases.Therefore, constitute a plurality of part metals layer 22c of metal level 22b, the both ends or one end of its thickness direction need join with adjacent both sides piezoelectric body layer 21.Constitute metal level 22b a plurality of part metals layer 22c thickness directions two ends not simultaneously with situation that adjacent both sides piezoelectric body layer 21 contacts under, can not fully give the spring function that connects adjacent piezoelectric body layer 21, so there is the situation of the effect of the displacement increase in the time of can not fully obtaining Piezoelektrisches mehrschichtelement is driven.

And then preferably at the near zone of adjacent piezoelectric body layer 21, width reduces (Fig. 4 (d)) to a plurality of part metals layer 22c gradually or width increases (Fig. 4 (e)) gradually along with close this piezoelectric body layer.Here, another function that metal level 22b is required is the stress that produces when relaxing Piezoelektrisches mehrschichtelement driving, displacement.In order to obtain this function, when Piezoelektrisches mehrschichtelement drives distortion, need mitigation to produce stress it is not converged at the interface of piezoelectrics 21 and metal level 22.In the present invention, in order further to improve this stress alleviating function, the profile of a plurality of part metals layer 22c is made as: especially at the near zone of adjacent piezoelectric body layer 21, along with near this piezoelectric body layer, width diminishes gradually or becomes big gradually, suppresses stress and converges.Thus, owing to can not concentrate with piezoelectrics 21 stress that metal level 22b joins, the displacement quantitative change is big, owing to can avoid the stress of element to converge in the driving displacement of holding element, so the piezo actuator of the high reliability of the big and good tolerance of addendum modification can be provided.

In addition, in metal level 22b, preferably between adjacent a plurality of part metals layer 22c, there is the gap.This be because, if in metal level 22b, there is megohmite insulant outside the metal ingredient, then when driving element, exist in piezoelectrics 21 and produce the part that can not apply voltage, the situation that the piezoelectricity displacement is increased, in addition, the stress during driving is concentrated easily.

On the other hand, if between a plurality of part metals layer 22c of component part metal level 22b, have the gap, then when the metal part branch applies stress, because the part in space is arranged, thus part metals layer 22c deformation energy disperses to relax stress.In addition, when the piezoelectrics 21 piezoelectricity displacements of joining with metal level 22b, because the gap is arranged, but thereby part clamping piezoelectrics 21, thereby with when whole face carries out clamping, compare, reduced the power of constraint piezoelectrics 21, so piezoelectric body layer 21 easy displacements can increase addendum modification.Thus, the displacement that can obtain element becomes bigger, and the high multilayer piezoelectric element of durability.

In addition, duplexer 23 is preferably the polygonal column.This be because, if duplexer 23 is cylinders, if not just Yuan words then central shaft can shake, so must make high-precision circle, thereby be difficult to adopt method for making based on the yield production type of firing simultaneously, in addition, even behind the duplexer of stacked circular shape, perhaps, also be difficult to the central shaft of aligned metal layer 22 accurately firing back grinding periphery and being cylindric.

To this, if the polygonal column then can form metal level 22 in the piezoelectrics 21 of having determined datum line, further can carry out stacked along datum line, so can adopt the central shaft of the method for making formation of yield production type, so can obtain the high element of durability as driving shaft.

In addition, in the present invention, the metal that constitutes metal level 22b preferably adopts silver or palladium or their compound.These metals are owing to having high thermal endurance, so can fire simultaneously firing temperature high piezoelectrics 21 and metal level 22.Therefore, can make outer electrode 25 with the temperature lower, so can suppress phase counterdiffusion fierce between piezoelectrics 21 and the outer electrode 25 than the sintering temperature of piezoelectrics 21.

Then, the method for making to the related Piezoelektrisches mehrschichtelement of present embodiment describes.At first, mix by PbZrO ₃-PbTiO ₃The adhesive that constitutes Deng the calcined powder of the piezoelectric ceramic of the perofskite type oxide that constitutes, by the organic polymer of acrylic compounds and butyral class etc., the plasticizer of DBP (repefral), DOP (dioctyl phthalate) etc., and make slurry, make by the known banded method of forming of scraping the skill in using a kitchen knife in cookery or calender bwol method etc. making this slurry become the ceramic printed-circuit board of piezoelectrics 11.

Then, in the metal dust of the formation metal level 22 of silver-palladium etc., add mixed adhesive and plasticizer etc. and make conductive paste, this conductive paste is printed on the upper surface of each tellite with the thickness of 1～40 μ m by silk screen printing etc.By the ratio of change adhesive and plasticizer and metal dust, or the order number of the mesh of change silk screen, or change the resist thickness that forms silk-screen patterns, thus can make the thickness of metal level 22 and the variations such as space in the metal level.

In addition, at stacked a plurality of tellites that print conductive paste, with the temperature of regulation this duplexer is being carried out under the state of weight being put thereon after the unsticking mixture handles, according to making the mode that has difference in the metal layer thickness not place weight and fire with 900～1200 ℃, make duplexer 23 thus.

At this moment, in the tellite of the part of non-active layer 24, the metal dust of the formation metal level 22 of interpolation silver-palladium etc., or during the tellite of the part of stacked non-active layer 24, metal dust by formation metal levels 22 such as printed silver-palladiums on tellite and the slurry that constitutes by inorganic compound and adhesive and plasticizer, thereby contraction behavior and shrinkage in the time of making the sintering of non-active layer 24 and other parts are consistent, so can form fine and close duplexer 23.

In addition, duplexer 23 is not limited to make by above-mentioned method for making, and the duplexer 23 that constitutes as long as can make alternately laminated a plurality of piezoelectrics 21 and a plurality of metal level 22 also can form by other method for makings.

Then, in glass powder, add adhesive and make silver-colored glass conductive paste, and it is configured as sheet, the living density of the sheet that (solvent dispersed) after the drying is controlled at 6～9g/cm ³The outer electrode that this sheet is transferred to column duplexer 23 forms face, with than the firing temperature of following temperature of the high temperature of the softening point of glass and silver point (965 ℃) and duplexer 23 (℃) the temperature below 4/5 cure.By like this, utilize the disappearance of dispersing of adhesive ingredients in the sheet that silver-colored glass conductive paste makes, can form the formed outer electrode 25 of porous matter electric conductor that is three-dimensional mesh configuration.

In addition, the stoving temperature of described silver-colored glass conductive paste and above-mentioned same is preferably 500～800 ℃.In addition, the softening point of the glass ingredient in the silver-colored glass conductive paste is preferably 500～800 ℃.

Then, the duplexer 23 that will be formed with outer electrode 25 is immersed in the silica gel solution, simultaneously silica gel solution is carried out vacuum degassing, thus at the inner filling gel of the groove of duplexer 23, from silica gel solution, pull out duplexer 23 afterwards, silica gel is covered the side of duplexer 23.Afterwards, be filled in the described silica gel curing that groove is inner and cover the side of duplexer 23 by making, thereby finish Piezoelektrisches mehrschichtelement of the present invention.

Then, lead is connected with outer electrode 25, applies the direct voltage of 0.1～3kV/mm to pair of external electrodes 25,, thereby finish the piezo actuator that has utilized Piezoelektrisches mehrschichtelement of the present invention by processing that duplexer 23 is polarized by this lead.If the voltage supply unit of lead with the outside is connected, apply voltage via lead and outer electrode 25 to metal level 22, then big displacement takes place because of inverse piezoelectric effect in each piezoelectrics 21, and the automobile fuel injection valve that for example can be used as thus to the engine spray fueling plays a role.

Because other are identical with first execution mode, so omit explanation.

＜injection apparatus 〉

Fig. 5 is the general profile chart of the related injection apparatus of expression one embodiment of the present invention.As shown in Figure 5, this injection apparatus at one end has 33 storing containers 31 inside of spray-hole, and depositing with above-mentioned execution mode is the Piezoelektrisches mehrschichtelement of the present invention of representative.In storing containers 31, configuration can open and close the needle valve 35 of spray-hole 33.In spray-hole 33 configuration fuel passage 37, it can be communicated with according to the action of needle valve 35.This fuel passage 37 connects with outside fuel supply source, all the time with constant high pressure to fuel passage 37 fuelings.Thus, if needle valve 35 is open with spray-hole 33, the fuel that then supplies to fuel passage 37 is ejected in the fuel chambers of not shown internal combustion engine with constant high pressure.

In addition, the internal diameter of the upper end of needle valve 35 increases, the piston 41 that configuration can be slided with the cylinder 39 that is formed in the storing containers 31.In addition, in storing containers 31, deposit the piezo actuator 43 that possesses above-mentioned Piezoelektrisches mehrschichtelement.

In such injection apparatus, if piezo actuator 43 is applied in voltage and extends, then push piston 41, needle valve 35 inaccessible spray-holes 33 stop the supply of fuel.In addition, if stop to apply then piezo actuator 43 contractions of voltage, disk spring 45 is pressed air cylinder 41 repeatedly, and spray-hole 33 is communicated with fuel passage 37, carries out the injection of fuel.

In addition, though the present invention is relevant with Piezoelektrisches mehrschichtelement and injection apparatus, but be not limited to the foregoing description, even the fuel injection device of automobile engine for example, the liquid injection apparatus of ink-jet etc., the driving element that carries in the precision positioning device of Optical devices etc. or the antihunting device etc., pressure sensor perhaps burns, detonation sensor (knock sensor), acceleration transducer, load sensors, ultrasonic sensor, the pressure-sensitive transducer, the sensor element that carries in yaw rate (yaw rate) transducer etc., and piezoelectric rotary instrument, Piezoelectric switches, piezoelectric transformer, beyond the circuit element that carries in the piezoelectricity circuit breaker etc., so long as adopt the element of piezoelectric property, can both implement.

Below, enumerate embodiment the present invention further is elaborated, but the present invention is defined in following embodiment.

Embodiment

(embodiment 1) piezo actuator that constitutes by Piezoelektrisches mehrschichtelement of the present invention of making as described below.

At first, mixing with average grain diameter is the lead zirconate titanate (PbZrO of 0.4 μ m ₃-PbTiO ₃) make slurry for calcined powder, adhesive and the plasticizer of the piezoelectric ceramic of main component, by scraping the ceramic printed-circuit board that making such as the skill in using a kitchen knife in cookery become the piezoelectrics 11 of thickness 150 μ m.

On a face of this ceramic printed-circuit board, by having added the conductive paste of adhesive in the silk screen print method printing silver-palladium alloy (silver-colored 95 quality %-palladiums, 5 quality %).At this moment,, utilize the conductive paste that has added adhesive in the silver-palladium alloy (silver-colored 95 quality %-palladiums, 5 quality %) to print, become the thickness of 5 or 10 μ m after feasible the firing in the part that forms other metal levels 12B.In addition, according to circumstances, in above-mentioned conductive paste, add the acrylic particles of 0.2 μ m and in metal level, generate the space.

In the part that forms high-resistance metal layer 12A, an amount of acrylic particles of adding average grain diameter 0.2 μ m in the particle that the surface of silver-palladium alloy (silver-colored 95 quality %-palladiums, 5 quality %) has been carried out oxidation processes, further utilize the conductive paste that has added adhesive to print, become the thickness of 1～6 μ m after feasible the firing.

Prepare 300 pieces as printed the sheet of conductive paste, prepare to become the tellite of protective layer in addition, and under begin stacked 30 pieces of protective layers, 300 pieces of duplexers, 30 pieces of protective layers, after pressurizeing, carry out degreasing and fire.Fire after keeping 2 hours under 800 ℃ the condition, fired 2 hours with 1000 ℃.The voidage of formed high-resistance metal layer 12A is represented by table 1.

In addition, the high-resistance metal layer 12A in the duplexer 13 is the represented number of plies of table 1.In addition, the configuration of this high-resistance metal layer 12A all is regular except test portion No.9.Particularly, the number of plies of high-resistance metal layer is 1 layer test portion No.1, and beginning has been disposed the high-resistance metal layer at the 150th layer above duplexer.In addition, the number of plies of high-resistance metal layer is 2 layers test portion No.2, has disposed the high-resistance metal layer above duplexer the 100th, 200 layer regularly.The number of plies of high-resistance metal layer is 5 layers test portion No.3, and beginning is that unit has disposed the high-resistance metal layer regularly with per 50 layers above duplexer.The number of plies of high-resistance metal layer is that 14 layers test portion is that unit disposes regularly with per 20 layers, and 59 layers test portion is that unit disposes regularly with per 5 layers.In addition, the number of plies of high-resistance metal layer be 10 layers test portion above duplexer, disposed the high-resistance metal layer interval rule with 26,27,27,28,28,28,28,28,27,27.In addition, the number of plies of high-resistance metal layer be 39 layers test portion above duplexer, as 7,8,7,8 alternately with the interval rule of 7 layers and 8 layers disposed the high-resistance metal layer.The number of plies of high-resistance metal layer is 20 layers a test portion, has disposed the high-resistance metal layer interval rule with 13,13,13,13,14,14,15,15,16,16,16,16,16,15,15,14,14,13,13,13.The number of plies of high-resistance metal layer is in 20 layers the test portion, the irregular test portion No.9 of the configuration of high-resistance metal layer, above duplexer, the arranged spaced with 5,5,25,25,15,10,20,20,10,10,10,10,10,20,20,10,15,25,25,5 the high-resistance metal layer.

Preparation is at high-resistance metal layer 12A, according to circumstances added the material of PZT, lead titanates, aluminium, titanium dioxide, silicon nitride, the contour resistance components of silicon dioxide.

Then, the softening point that in the laminar silver powder of average grain diameter 2 μ m with the silicon that surplus average grain diameter is 2 μ m is main component is in 640 ℃ the mixture of amorphous glass powder, add adhesive, its proportion is 8 Quality Mgmt Dept with respect to silver powder and glass powder total quality 100 Quality Mgmt Dept, fully mix, make silver-colored glass conductive paste, the silver-colored glass conductive paste of making like this is formed on the release film by silk screen print method, peel off by release film dry back, obtains the sheet of silver-colored glass conductive paste.In addition, the average grain diameter of laminar powder is measured according to following.That is, utilize scanning electron microscope (SEM) to take the photo of powder, on this photo, draw straight line, measure the length that 50 particles and straight line intersect, get it and on average obtain average grain diameter.

In addition, the sheet transfer printing layer of described silver-colored glass cream is laminated on the face of outer electrode 15 of duplexer 13, under 700 ℃ condition, carries out 30 minutes cure, form pair of external electrodes 15.

Afterwards, connect the line to outer electrode 15, apply the DC electric field 15 minutes of 3kV/mm by this lead to the outer electrode 15 of positive pole and negative pole, the piezo actuator that has adopted Piezoelektrisches mehrschichtelement shown in Figure 1 is made in the processing that polarizes.When resulting Piezoelektrisches mehrschichtelement applies the direct voltage of 170V, in all piezo actuators, obtain addendum modification at stacked direction.

And then, with the frequency of 300Hz at ambient temperature to this piezo actuator apply 0～+ alternating voltage of 170V, carry out the test of Continuous Drive, up to carrying out 2 * 10 ⁹Inferior.Test is undertaken by per 100.After the test, calculate the ratio that has reached the sample that destroys, in table 1, represent as the destructive rate after the test.In addition, adopt metallurgical microscopes, SEM etc. to observe laminated section simultaneously, calculate the quantity that produces the layer of peeling off.And then, what will obtain divided by the addendum modification of initial Piezoelektrisches mehrschichtelement with the absolute value of the difference of the addendum modification of the addendum modification of the Piezoelektrisches mehrschichtelement after the addendum modification of initial Piezoelektrisches mehrschichtelement and the test and the Piezoelektrisches mehrschichtelement after the test is on duty with the value after 100 times, as the rate of change of the addendum modification that drives the test front and back, expression in table 1.The result represents in table 1.

Table 1

According to this table, test portion No.I-1 as a comparative example, the quantity of the high-resistance metal layer in the Piezoelektrisches mehrschichtelement is 1, thus dispersive stress well, and then the crack that produces spreads on the whole at element, so the failure probability after the test is greatly to 10%.In addition, the quantity that produces the layer peel off of the layer in duplexer mostly is 100.And then the rate of change that drives the addendum modification before and after testing is greatly to 10%, and durability reduces.

To this, as test portion number I-2～32 of embodiments of the invention, Continuous Drive 2 * 10 ⁹Destructive rate after inferior is below 3%, compares with as a comparative example test portion number I-1, and is very outstanding aspect durability.

Especially, disposed test portion, for example test portion No.I-6 of high-resistance metal layer regularly and do not had the test portion No.I-9 of the configuration of rule to compare, the destruction after not testing, the rate of change of the addendum modification before and after the test is little, thereby outstanding aspect durability.

In addition, dispose 20 layers high-resistance metal layer, voidage test portion No.I-10～16 bigger than other metal levels of high-resistance metal layer regularly, the rate of change that drives the addendum modification before and after testing is little of below 2.0%, and is outstanding as the Piezoelektrisches mehrschichtelement durability.In addition, in the voidage with the high-resistance metal layer was made as 40～99% test portion No.I-11～16, the rate of change that drives the addendum modification before and after the test was further little of below 1.8%, thereby durability is outstanding.

In addition, in test portion No.I-17～16 that the containing ratio of the high resistance composition in the high-resistance metal that disposes 20 floor height Resistiue metal layers, high-resistance metal layer is regularly Duoed than the containing ratio of the high resistance composition in other metal levels, the test portion that does not have destruction, the variation that drives the addendum modification before and after testing is also significantly little of 0.4～0.9%, and is outstanding as the Piezoelektrisches mehrschichtelement durability.In addition, adopted the test portion of PZT, lead titanates, aluminium oxide, titanium dioxide as the high resistance composition, durability is outstanding.

And then, in changing high-resistance metal layer and other metal layer thickness, having confirmed that the thickness of high-resistance metal layer is less than the test portion No.I-6 of the effect of other metal layer thickness, test portion No.I-28～32, test portion No.I-27 greater than other metal layer thickness compares with the thickness of high-resistance metal layer, the rate of change that drives the addendum modification before and after testing is little of below 1.6%, and durability is outstanding.

And then in the test portion more than 1000 times of the resistance of other metal levels, the high-resistance metal layer can not peeled off at the resistance that the high-resistance metal layer is controlled at 1/10～1000 times test portion or high-resistance metal layer with respect to the resistance ratio of piezoelectric body layer, and durability is outstanding.

Deposit the injection apparatus energy efficiency of Piezoelektrisches mehrschichtelement of the present invention and spray well, durability is also outstanding, is the product useful to earth environment.

(embodiment 2)

The piezo actuator of making by Piezoelektrisches mehrschichtelement of the present invention as described below.At first, mixing with average grain diameter is the lead zirconate titanate (PbZrO of 0.4 μ m ₃-PbTiO ₃) make slurry for calcined powder, adhesive and the plasticizer of the piezoelectric ceramic of main component, by scraping the ceramic printed-circuit board that making such as the skill in using a kitchen knife in cookery become the piezoelectrics 21 of thickness 150 μ m.

On a face of this ceramic printed-circuit board, form sheet by the conductive paste that has added adhesive in the silk screen print method printing silver-palladium alloy (silver-colored 95 quality %-palladiums, 5 quality %), and stacked 300 pieces are fired.Fire under the condition that remains on 800 ℃, fire with 1000 ℃ afterwards.

At this moment,, print, make its thickness that becomes 10 μ m,, print, make it become the thickness of 5 μ m with the plate-making of resist thickness 10 μ m in the part that forms part metals layer 22c with the plate-making of resist thickness 20 μ m in the part that forms metal level 22a.Part metals layer such configuration as shown in table 2.The metal level 22b that part metals layer 22c constitutes becomes the form that has disposed 6 part metals layer 22c shown in Fig. 3 (b).And then test portion number II-5 further is subdivided into 1 part metals layer 22c 5 of vertical 5 horizontal strokes totally 25 part metals layers.That is, in test portion number II-5,150 part metals layers of each layer configuration.

Then, the softening point that in the laminar silver powder of average grain diameter 2 μ m with the silicon that surplus average grain diameter is 2 μ m is main component is in 640 ℃ the mixture of amorphous glass powder, add adhesive, its proportion is 8 Quality Mgmt Dept with respect to silver powder and glass powder total quality 100 Quality Mgmt Dept, fully mix, make silver-colored glass conductive paste.The silver-colored glass conductive paste of making like this is formed on the release film by silk screen print method, and peel off by release film dry back, obtains the sheet of silver-colored glass conductive paste.

In addition, the sheet transfer printing layer of described silver-colored glass cream is laminated on the outer electrode formation face of duplexer 23, under 700 ℃ condition, carries out 30 minutes cure, form outer electrode 25.

Afterwards, connect the line to outer electrode 25, apply the DC electric field 15 minutes of 3kV/mm by this lead to the outer electrode 25 of positive pole and negative pole, the piezo actuator that has adopted Piezoelektrisches mehrschichtelement shown in Figure 3 is made in the processing that polarizes.

When resulting Piezoelektrisches mehrschichtelement applies the direct voltage of 170V, in all piezo actuators, obtain addendum modification at stacked direction.

And then, with the frequency of 150Hz at ambient temperature to this piezo actuator apply 0～+ alternating voltage of 170V, carry out the test of Continuous Drive, up to carrying out 1 * 10 ⁹Inferior.The result is as shown in table 2.

According to table 2, test portion number II-6 as a comparative example, the stress that is applied to stacked interface concentrates on a bit, and load increases, and generation is peeled off, and produces sound or noise.

To this, as test portion number II-1～5 of embodiments of the invention, even in Continuous Drive 1 * 10 ⁹After inferior, the element addendum modification can significantly not descend yet, and has the addendum modification as the required actual effect of piezo actuator, can produce the piezo actuator that can not produce misoperation and have outstanding durability.

Especially, the test portion No.II-3 that has disposed stress relaxation layer and stress concentrated layer adjacent one another are can not only increase the addendum modification of element across piezoelectrics, and can make the stable cascade type actuator of element addendum modification.And then, clip the test portion No.II-4,5 of stress relaxation layer across piezoelectrics, not only can increase the addendum modification of element, and the element addendum modification is changed, because durability is extremely outstanding, so can obtain the stable cascade type actuator of element addendum modification.

Piezoelektrisches mehrschichtelement of the present invention and injection apparatus are not limited to above execution mode, can carry out various changes in the scope of claim record of the present invention.For example, in the above-described embodiment, the example that the opposed side at duplexer 13,23 has been formed outer electrode 15,25 is illustrated, but also can form pair of external electrodes 15,25 in adjacent side.

Claims (10)

1. Piezoelektrisches mehrschichtelement, it is by forming piezoelectric body layer and the alternately laminated multilayer of metal level,

A plurality of described metal levels comprise a plurality of high-resistance metal layers, and the resistance of this high-resistance metal layer is higher than the resistance of the metal level of adjacent both sides.

2. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

A plurality of described high-resistance metal layers clip a plurality of other metal levels beyond this high-resistance metal layer respectively and dispose.

3. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

Described high-resistance metal layer disposes with some cycles.

4. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

The voidage of described high-resistance metal layer inside is greater than the voidage in a plurality of other metal levels beyond this high-resistance metal layer.

5. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

Described high-resistance metal layer comprises the high resistance composition of a plurality of other metal floor heights beyond this high-resistance metal layer of resistance ratio, and the containing ratio of this high resistance composition is than the containing ratio height of the high resistance composition in described other metal levels.

6. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

The thickness of described high-resistance metal layer is thinner than a plurality of other metal levels beyond this high-resistance metal layer.

7. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

The resistance of described high-resistance metal layer is 1/10～1000 times of resistance of described piezoelectric body layer.

8. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

The resistance of described high-resistance metal layer is more than 1000 times of resistance of metal level of the adjacent both sides of this high-resistance metal layer.

9. Piezoelektrisches mehrschichtelement according to claim 1 is characterized in that,

In the side of described duplexer, form the pair of external electrodes that is connected with described a plurality of metal levels.

10. injection apparatus comprises container with squit hole and each the described Piezoelektrisches mehrschichtelement in the claim 1～9, and the driving by described Piezoelektrisches mehrschichtelement sprays the liquid of filling in the described container from described spray-hole.

Images