JPS6019968A - Electrostriction type liquid pressure generating device - Google Patents

Abstract

PURPOSE:To enable an electrostriction element to be always positioned in a correct place, by a method wherein an automatic centering mechanism is installed led between an upper casing side plate and an upper retainer member or between a lower retainer member and a piston. CONSTITUTION:The lower end of an electrostriction element 126 is centered by a lower retainer member 134, and meanwhile, the lower retainer member 134 is centered with the aid of an annular projection 150 on a piston. The upper end of the electrostriction element is centered with a casing by means of an automatic centering mechanism comprising hollows 136, 138 and a sphere 140. Even if the center of the upper end of the electrostriction element is positioned eccentrically to the axis of a casing, hollows 136 and 138 are aligned with each other through movement of a ball 140 in conformity with the taper surface of the hollows 136 and 138, resulting in alignment of the center of an upper retainer member 132 with the axis of a casing.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a hydraulic pressure generating device using an electrostrictive element.

[Background technology]

The inventors have already filed an application for a hydraulic pressure generating device in which a piston is connected to a columnar electrostrictive element and the piston is changed by mechanical strain generated in the electrostrictive element. When a voltage is applied, distortion occurs in the electrostrictive element almost simultaneously, and the time lag is extremely short. Therefore, such a hydraulic pressure generating device has excellent high-speed response and can accurately control the generated liquid according to the input voltage signal.

Generally, an electrostrictive element is formed into a columnar shape by laminating a plurality of thin disks made of an electrostrictive material. Therefore, when a local load is applied to each electrostrictive disk, there is a problem that it is easily destroyed. Furthermore, if the electrostrictive element is installed eccentrically with respect to the axis of the casing that houses the electrostrictive element and the piston, or if the end surface of the electrostrictive element is not parallel to the supporting surface of the electrostrictive element, However, there is a problem in that cracks occur in the periphery of each electrostrictive disk, and the amount of strain in the electrostrictive element and thus the amount of displacement of the piston becomes unstable.

[Summary of the invention]

The present invention was devised in view of the problem of tilting in the prior art, and is an electrostrictive hydraulic pressure generator that can always position an electrostrictive element at an accurate position and obtain a stable amount of strain. The purpose is to provide a device.

The electrostrictive liquid pressure generator of the present invention includes a casing body having an axial bore and an upper end and a lower end, an upper casing side plate that closes the upper end, and a liquid suction port and a liquid discharge port that are fixed to the lower end. a casing consisting of a lower casing side plate having a lower casing side plate; a columnar electrostrictive element housed coaxially within the casing so as to be able to expand and contract in the axial direction without colliding with the casing; and upper and lower ends of the electrostrictive element. an upper support member and a lower support member respectively fixed to and made of an insulating material;
a circuit for supplying voltage to the electrostrictive element; and a circuit connected to the lower end of the electrostrictive element via the lower support member during operation, and installed in a casing bore in a fluid-tight and slidable manner to connect the casing bore and the lower casing. The device includes a piston that forms a liquid pressurizing chamber between it and a side plate, and means for applying an initial compressive load to the electrostrictive element. The present invention is characterized in that at least one of between the upper casing side plate and the upper support member and between the lower support member and the piston is arranged such that the axis of the electrostrictive element is aligned with the axis of the casing. This is because a self-aligning mechanism has been installed.

In one embodiment of the present invention, the self-aligning mechanism includes a conical recess formed on the lower surface of the upper casing side plate, a conical recess formed on the upper surface of the upper support member, and the two conical recesses formed on the upper surface of the upper support member.
It consists of a rigid sphere disposed between two depressions, the two depressions being aligned with the gauging axis.

In other embodiments, it is possible to provide a self-aligning mechanism between the support member and the piston, and this self-aligning mechanism may be formed by a conical recess formed on the lower surface of the lower support member. , consists of a conical depression formed on the top surface of the piston and a rigid sphere placed between these two depressions,
These recesses are also aligned with the casing axis.

If the electrostrictive element is supported in this way, the electrostrictive element will not be installed eccentrically with respect to the casing due to the cooperative action of the sphere and the conical recess, and damage to the electrostrictive element will be prevented. At the same time, a stable amount of distortion can be obtained.

The self-aligning mechanism consists of conical recesses formed on the lower surface of the upper casing side plate and the upper surface of the piston, respectively, and partial spherical surfaces formed on the upper surface of the upper support member and the lower surface of the support member described below, respectively. The partially spherical surface can be aligned with the casing axis.

In yet another embodiment, the upper casing W111 plate is axially movably mounted with adjusting means for adjusting the initial compressive load of the electrostrictive element, and the self-aligning mechanism is a cone formed on the upper surface of the upper support member. It can be composed of a round shape and a partial spherical surface formed at the lower end of the initial compression load adjustment means,
This<? '! 'The adjustment means are aligned with the casing axis of the stone.

Preferably, the initial compressive load adjusting means has an axial through hole, an upper electrode plate is held between the upper support member and the electrostrictive element, and an upper electrode plate is held between the lower support member and the electrostrictive element. A lower electrode plate is contained in the lower electrode plate, and a part of this lower electrode plate extends to the piston, and a voltage supply circuit is inserted into the axial through hole of the initial compression load adjusting means, and extends to the upper part of the lower electrode plate. It includes a lead wire connected to an electrode, an upper electrode plate, an electrostrictive element, a lower electrode plate, a piston, and a grounded casing.

When a self-aligning mechanism is configured with a sphere and a conical recess, the upper support member, the electrostrictive element, and the lower support member are provided with axial through holes that are aligned with each other along the casing axis, and these through holes are formed. A tension spring can be disposed within the hole and connected to the sphere at one end and to the lower support member at the other end. With this configuration, the tension springs can hold the sphere, the upper and lower support members, and the electrostrictive element integrally with each other.

The initial compressive load applied to the electrostrictive element can be adjusted.

In another embodiment, the casing body is provided with a cooling oil inlet near its upper end, the casing side plate is provided with a cooling oil outlet in the center, and the piston is provided with a through hole for the electrostrictive element and the casing internal space. A cooling oil passage that communicates with the sphere is provided, and a cooling oil passage that communicates between the through hole of the electrostrictive element and the cooling oil outlet is provided in the sphere. In this way, the electrostrictive element can be effectively cooled, and reduction in the electrostrictive effect due to temperature rise can be avoided.

Further, in a preferred embodiment, the sphere is made of an electrically conductive material, the portion of the upper casing side plate forming the recess is made of an insulating material, and one end of the sphere is connected to the electrical terminal and the other end is connected to the casing. An upper electrode plate is held between the upper support member and the electrostrictive element, and a part of this upper electrode plate extends to the recess of the upper support member and contacts the sphere. Moreover, a lower electrode plate is held between the lower support member and the electrostrictive element, and a part of this lower electrode plate extends to the piston, and the voltage supply circuit is connected to this electric terminal. It includes a conductive sphere, an upper electrode plate, an electrostrictive element, a lower electrode plate, a piston, and a grounded casing. In this embodiment, the electrical terminal is present only on the positive side and the negative side is grounded, so the device can be made smaller and easier to assemble.

Other features and advantages of the invention will become clearer in the following description.

〔Example〕

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same or similar parts common to each embodiment are represented by similar reference numerals, and redundant description will be omitted.

FIG. 1 shows a first embodiment of the present invention, in which the electrostrictive hydraulic pressure generator 100 is constructed as a fuel injection valve. This device 100 has a casing 102
has. The casing 102 includes a cylindrical casing body 106 having an axial bore 104, an upper casing side plate 108 integrally formed with the body 106, and a lower casing fixed to the lower end of the body 1o6 by a lower body edge 110t. It consists of a side plate 112. The casing body 106 is provided with a cooling oil inlet 114 and an outlet 116 for circulating cooling oil in the casing interior space. A liquid suction port 118 and a liquid discharge port 120 are formed in the lower side plate 112 of the casing. The suction port 118 can be connected to a fuel tank 122 via a check valve 121 . Lower side plate 1
12 is a nozzle 12 equipped with a spring-loaded valve body 123;
4 is a provision.

A columnar electrostrictive element 12 is disposed inside the casing 102 coaxially with the casing and without touching the casing.
6 is accommodated. The columnar electrostrictive element 126 is made of an electrostrictive material whose main component is lead zirconate titanate.
It can be constructed by stacking a large number of disks (not shown) with a thickness of ~1 cm, and when a voltage of several hundred volts is applied to both ends of each disk, the axial displacement is about 50 μm. It is something that gives rise to As is well known, positive side electrode foils and negative side electrode foils (not shown) are alternately held between the electrostrictive disks, and the positive side electrode foil group is connected to the positive lead wire 128, and The negative electrode foil group is connected to a negative lead wire 130.

The electrostrictive element 126 has an upper support member 1 made of an insulating material arranged at its upper and lower ends, respectively! +2 and lower support member 134
Supported by Conical recesses 136 and 138 facing each other along the casing axis are formed on the upper surface of the upper support member 132 and the lower surface of the upper side plate 108, respectively. Ball 14
0 is the placement.

The lower support member 134 is connected to the bore 10 of the casing body 106.
4, which abuts a piston 142 that is slidably fitted within the piston 142. A sealing O-ring 14 is attached to the outer circumference of the piston 142.
4, and a pressurizing chamber 146 is formed between the piston 142, the bore 104, and the lower side plate 112.

A disc spring 14 is provided between the piston 142 and the lower side plate 112.
8 is inserted in a compressed state and applies an initial compressive load to the electrostrictive element 126. Piston 142 is provided with an annular projection 150 to allow centering of lower support member 134 relative to the piston.

The leads 128, 150 are insulated from the casing by insulation pieces 152, 154 mounted on the upper side plate 108.

In operation, when a predetermined voltage is applied between the lead wires 128 and 150, the electrostrictive element 126 expands in the axial direction, displacing the piston 142 downward against the action of the disc spring 148. Therefore, the fuel in the pressurizing chamber 146 is injected from the nozzle 124. When the voltage is lowered, the electrostrictive element contracts and the piston retreats upward under the action of the disc spring 148, so that the fuel flows through the check valve 121 to the suction port 118.
It is inhaled from

In this embodiment, the lower end of the electrostrictive element 126 is centered by a lower support member 134, which in turn is centered by an annular projection 150 of the piston. Therefore, the lower end of the electrostrictive element is centered with respect to the casing. The upper end of the electrostrictive element is a recess 136,1
It is centered with respect to the casing by a self-centering mechanism constituted by a steel ball 38 and a steel ball 140. That is, even if the center of the upper end of the stain distortion element is eccentric from the casing axis for some reason, the steel ball 140 moves along the tapered surfaces of the recesses 136 and 138 to align the recesses 136 and 138 with each other. The center of the upper support member 132 is aligned with the casing axis. Therefore, no local stress acts on the electrostrictive element, and a stable amount of strain can be ensured.

FIG. 2 shows a hydraulic pressure generating device 200 according to a second embodiment of the present invention.
shows. What is different from the first embodiment is that conical depressions 260 and 261 are provided on the lower surface of the lower support member 234 and on the upper surface of the piston 242, respectively.
, 261, a steel ball 262 is placed between them. The depressions 236, 238 and the steel ball 240 constitute one self-aligning mechanism, and the depressions 260, 261 and the steel ball 262 constitute the other self-aligning mechanism.

The third cabinet shows a third embodiment 300 of the present invention. The difference from the second embodiment is that steel balls are not used, and the surfaces of the supporting members 332 and 334 provided above and below the electrostrictive element 326, opposite to the surface in contact with the electrostrictive element 326, are formed into a partially spherical surface 565. 566, and is configured to contact the conical recess 338 of the upper side plate 308 of the casing 302 and the conical recess 361 of the piston 342. The operation and effect are the same as in the second embodiment.

FIG. 4 shows a hydraulic pressure generating device 400 according to a fourth embodiment of the present invention.
shows. An adjustment screw 470 for adjusting the initial compressive load of the electrostrictive element 426 is screwed into an internally threaded label provided on the upper side plate 408 of the casing 402, and a lock nut 471
Fixed by The tip 472 of the adjustment screw 470 is hemispherically shaped and engages a conical recess 436 in the upper support member 432. In this embodiment, the hemispherical tip 472 of the adjustment screw 470 and the recess 436 of the upper support member 432 form a self-centering mechanism.

The advantage of this embodiment is that the electrostrictive element 4 is
The initial load applied to 26 can be adjusted by adjusting screw 470. Generally, since an electrostrictive element is constructed by laminating a large number of thin circles a, the amount of strain changes with respect to the load due to the presence of intervening electrode foils and the like. Therefore, by changing the initial load, it is possible to adjust the amount of strain.

Adjustment screw 470 simultaneously functions as part of a self-centering mechanism.

5 and 6 show a hydraulic pressure generating device 500 according to a fifth embodiment of the present invention. This embodiment is a modification of the embodiment shown in FIG.
576 and 577 are provided respectively. Upper support member 532
The through hole 575 is connected to the recess 536. 6th
As can be clearly seen from the figure, the sphere 540 is provided with a protrusion 578, and the protrusion 578 is provided with a hole 579.

A tension coil spring 580 is installed so as to pass through the through holes 575, 577 of the support members 552, 534 and the through hole 576 of the electrostrictive element 526, and one end of the spring 580 is inserted into the hole 5.
79, and the other end is fixed to the lower support member 534 via a stopper 581. Thus, the sphere 540,
Upper support member 532, electrostrictive element 526, lower support member 5
34, spring 580. The stopper 581 is an integral unit. The sphere 540 is attached to the upper side plate 508 of the casing 502.
It is in contact with the depression 538.

The operation of this embodiment is as follows. Due to the cooperation of the sphere 540 and the depressions 536 and 538, the electrostrictive element is self-aligned as in the first embodiment. In addition, since the sphere 540, the support members 532, 5'34, and the electrostrictive element 526 are integrally held together by the spring 580, it is easy to assemble them into one assembly.

Furthermore, by appropriately selecting the tensile force of the spring 580, an appropriate initial load can be applied to the electrostrictive element.

FIG. 7 shows a hydraulic pressure generating device 600 according to a sixth embodiment of the present invention.
shows. This device 600 is similar to the embodiment of FIGS. 5 and 8g6, with a sphere 640, an upper support member 632
, electrostrictive element 626, lower support member 634, stopper 68
11'i are held together integrally by tension springs 680. A cooling oil inlet 614 is provided at the top of the main body 606 of the casing 602 . Cooling oil outlet 616 is provided in upper side plate 60B and opens into recess 638.

The piston 642 has an internal space 682 of the casing 602.
A cooling oil passage 683 communicating with the through hole 676 of the electrostrictive element 626 is provided in the sphere 640, and a cooling oil outlet 616 is provided in the sphere 640.
A cooling oil passage 684 is provided that communicates with the through hole 676. Thus, the cooling oil enters the inlet 614, the interior space 682,
It can flow through the passage 683, the through hole 676, the passage 684, and the outlet 616 in this order.

Regarding the operation of this embodiment, a self-centering effect is obtained by the cooperation of the sphere 640 and the depressions 636 and 638. Furthermore, the effect of the tension spring 6800 is similar to that of the embodiments of FIGS. 5 and 6. In addition, the electrostrictive element can be effectively cooled. Generally, when an electrostrictive element is driven, its temperature increases, but when the temperature of the element reaches a certain point, the electrostrictive effect disappears. Therefore, it is desirable to cool the electrostrictive element under severe usage conditions. In this embodiment, since the cooling oil is configured to pass through the central through hole of the electrostrictive element, the cooling effect is large.

8 and 9 show a hydraulic pressure generating device 700 according to a seventh embodiment of the present invention. Upper support member 732 and electrostrictive element 726
An upper electrode plate 785 is held between the lower support member 734 and the element 726, and a lower electrode plate 786 is held between the lower support member 734 and the element 726. These members and sphere 740 are held together by a tension spring 780 that extends into central throughbore 776 of element 726. The upper electrode plate 785 has a flat plate portion 785a.
It consists of a cylindrical portion 785b extending upward, and a protrusion 785C bent to widen at the end. The flat plate portion 785a is the electrostrictive element 7
26 and the upper support member 732, the protrusion 785C
is embedded between the sphere 740 and the recess 736 of the upper support member 732. The lower electrode plate 786 consists of a flat plate portion 786a and a rectangular protrusion i7B6b extending downward. The flat plate portion 786a is contained between the electrostrictive element 726 and the lower support member 754, and the protrusion 786b is bent inward after passing through the slit 734a of the lower support member 734, and is contained between the piston 742 and the lower support member 7340. be absorbed.

The sphere 740 is made of a conductive material such as metal, and has a spring attachment protrusion 778 extending downward, and a terminal portion 787 extending upward for connecting a lead. In order to ensure electrical insulation with the casing 702, a door 88 made of resin or ceramic is fixed to the upper side plate 70B.
A cover 789 made of an elastic material is fitted around the terminal portion 787. The sheet 788 is provided with a recess 738. A positive lead wire is connected to the terminal portion 787. Thus, when a voltage is applied, the terminal portion 787 and the sphere 7
40, the upper electrode plate 785, the electrostrictive element 726, the lower electrode plate 786, the piston 742, the casing 702, and the ground.

In this embodiment, in addition to the self-centering function due to the presence of the sphere 740, the function of adjusting the initial load using the spring 780, and the function of integrating the components, there is an advantage that the current supply circuit is simplified. That is, the negative side of the circuit is connected to the body ground, and the terminal is only present on the positive side. Therefore, it is easy to assemble, and the outer diameter of the device can be made thinner, making it possible to downsize the device.

10 and 11 show a hydraulic pressure generating device 800 according to an eighth embodiment of the present invention. Similar to the embodiment shown in FIG. 4, an initial compression load adjustment screw 870 with a rounded lower end 872 is screwed into a screw hole in an upper side plate 808 of a casing 802 and fixed with a lock nut 871. However, in this embodiment, the adjustment screw 870 is hollow. , upper and lower electrode plates 885 and 886 are provided at the upper and lower ends of the electrostrictive element 826,
It is sandwiched between upper and lower support members 8'33 and 834. Upper electrode plate 8
85 consists of a flat plate part 885a and a protrusion 885b, and the protrusion 8
85b is connected to the positive lead wire 828. The lower electrode plate 886 includes a flat plate portion 886a and a cylindrical portion 88 extending downward.
6b, and a protrusion 886C that is bent into a shape that widens toward the end. The flat plate portion 885a of the upper electrode plate 885 is the electrostrictive element 82.
6 and the upper support member 832, the lower electrode plate B
The flat plate portion 886a of B6 includes the electrostrictive element and the lower support member 864.
Sandwiched between 0 and 0.

On the upper end side of the electrostrictive element 826, the self-aligning mechanism is formed by the rounded lower end 872 of the adjusting screw 870 and the recess 836 of the upper support member 832. Electrostrictive element 8
On the lower end side of 26, the self-aligning mechanism includes a recess 860 provided on the lower surface of the lower support member 834 and a piston 842.
It is made up of a recess 861 provided on the top surface and a metal sphere 862. An electrically insulating member 890 having a positive lead wire 828 passed therethrough is inserted into the hollow adjustment screw 870. The cylindrical portion 886b of the lower electrode plate 886 is connected to the lower support member 8.
The protrusion 886C extends within the through hole 877 of the sphere 86.
It is in contact with 2. Thus, when a voltage is applied, the lead wire 828, the upper electrode plate 885, the electrostrictive element 826 . Lower electrode plate 8861 sphere 862, piston 842, disc spring 8
48, the casing 802, and the ground.

In this example, in addition to the self-aligning function, the initial load of the electrostrictive element can be adjusted, and the negative terminal of the current-carrying circuit is grounded to the body, so that only the positive lead wire is present, so the outer diameter of the device can be made thinner and more compact.

[Brief explanation of drawings]

1 to 4 respectively show the first embodiment of the present invention. 2nd゜3rd. A longitudinal cross-sectional view of the fourth embodiment, a coffin 5 is a longitudinal cross-sectional view of the fifth embodiment,
6 is a partially enlarged sectional view of FIG. 5, FIG. 7 is a longitudinal sectional view of the sixth embodiment, FIG. 8 is a longitudinal sectional view of the seventh embodiment, and FIG. 9 is an example of the seventh embodiment. FIG. 10 is an exploded perspective view of the members of the
A vertical sectional view of the embodiment, and FIG. 11 is an exploded perspective view of some members of the eighth embodiment. 100.200,300,400,500゜600.7
00.800... Electrostrictive hydraulic pressure generator, 102
．． 302, 402, 602, 702, 802...
・Casing, 104...Axial bore, 10
6...Casing body, 108.3[38°408,508,608,808...Mountain top casing g,! 1st edition, 110...Lower casing side plate, 118...Suction port, 120...Discharge port, 126.326,426,526,626゜726
．． 826... Electrostrictive element, 132, 33.2° 432.532, 632, 732, 832...
Upper support member, 134, 234, 334, 534°6
34.734,834... Lower support member, 15
6.2"6.4'56.536,63/). 736.836... Recess in upper support member, 1
38.238,338,538,638°738...
...Darkness on the upper casing side plate, 140.240,
540,640,740... sphere, 142,
542,642,742. B42...Piston, 144...0 ring, 146...Pressure chamber, 14B...Disc spring, 260°860
・・・・・・The structure of the lower support member, 261°861・
...Piston recess, 262.862...
...Sphere, 470, E370...Adjustment screw,
580.68o, 78o...Tensile force spring. 785.8! '15... Upper electrode plate, 786°886... Lower electrode plate. Patent applicant Japan Auto Parts Research Institute Co., Ltd. Patent attorney Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Kyo Nakayama Patent attorney Akira Yamaguchi Figure 6/9 Figure 87'. ε 48 110th 885 885 (90): 32 5 no 800: 2G, 77 86 34 62 b) Ko

Claims (1)

[Claims] 1. A casing body having an axial bore and having an upper end and a lower end, an upper casing side plate that closes the upper end, and a liquid suction port and a liquid discharge port that are fixed to the lower end. a casing comprising: a lower casing side plate provided with a columnar electrostrictive element; an upper support member and a lower support member each fixed and made of an insulating material; a circuit for supplying voltage to the electrostrictive element; a piston fluid-tightly and slidably mounted to the casing bore and the lower casing side plate to define a fluid pressurizing chamber between the casing bore and the lower casing side plate; and a biasing means for applying an initial compressive load to the electrostrictive element. An electrostrictive hydraulic pressure generating device comprising: at least one of between the upper casing side plate and the upper support member and between the lower support member and the piston,
An electrostrictive hydraulic pressure generating device characterized by being provided with a self-aligning mechanism for aligning the axis of an electrostrictive element with the axis of a casing. 2. The self-aligning mechanism consists of a conical recess formed on the lower surface of the upper casing side plate, a conical recess formed on the upper surface of the upper support member, and a rigid sphere disposed between the two recesses. 2. The electrostrictive hydraulic pressure generating device according to claim 1, wherein the two depressions are arranged in alignment with the axis of the casing. 3. The self-aligning mechanism includes a conical recess formed on the lower surface of the lower support member, a running conical recess formed on the upper surface of the piston, and a rigid mechanism disposed between the two <t holes. The electrostrictive hydraulic pressure generating device according to claim 2, wherein the electrostrictive hydraulic pressure generator comprises a sphere, and the two depressions are arranged in alignment with the axis of the casing. , the self-aligning mechanism is formed from a traveling conical recess formed on the lower surface of the upper casing side plate and the upper surface of the piston, respectively, and a partial spherical surface formed on the upper surface of the upper support member and the lower surface of the lower support member, respectively; 5. The electrostrictive hydraulic pressure generating device according to claim 1, wherein the recess and the partial spherical surface are aligned with the casing axis. The self-aligning mechanism is provided with an adjusting means that is attached to the side plate of the upper casing so as to be movable in the axial direction and adjusts the initial compressive load of the electrostrictive element, and the self-aligning mechanism adjusts the initial compressive load and the conical recess formed on the upper surface of the upper support member. The electrostrictive hydraulic pressure according to claim 1, wherein the recess extending from a partial spherical surface formed at the lower end of the adjusting means and the initial compression load adjusting means are aligned with the casing axis button. Generation device. 6. The electrostrictive hydraulic pressure generation device according to claim 2, wherein the upper support member, the electrostrictive element, and the lower support member have an axial direction aligned with each other along the casing axis. A through hole is provided in each hole, and a tension spring is disposed in each of the through holes, one end of which is connected to the sphere and the other end connected to the lower support member, and the tension spring is connected to the sphere. An electrostrictive hydraulic pressure generating device characterized in that a vertical support member and an electrostrictive element are held integrally with each other, and a predetermined initial compressive load is applied to the electrostrictive element. 2. Claim 6 2. The electrostrictive hydraulic pressure generator according to paragraph 1, wherein the casing body has a cooling oil inlet near the upper end, the upper casing side plate has a cooling oil outlet in the center thereof, and the upper casing side plate has a cooling oil outlet in the center thereof. The piston is provided with a cooling oil passage that communicates the through hole of the electrostrictive element with the inner space of the casing, and the sphere is provided with a cooling oil passage that communicates the through hole of the electrostrictive element with the cooling oil outlet. An electrostrictive hydraulic pressure generating device characterized by: a. The electrostrictive hydraulic pressure generating device according to claim 6, wherein the sphere is made of a conductive material, and the recess is formed in the side plate of the upper casing. The forming part is made of an insulating material, one end of the electric terminal is connected to one sphere, and the other end is extended outside the casing, and an upper electrode plate is provided between the upper support member and the electrostrictive element. A part of the upper electrode plate is held in place and extends to the recess of the upper support member and comes into contact with the sphere, and a lower electrode plate is held in between the lower support member and the electrostrictive element. A part of the lower electrode plate extends to the piston, and the voltage supply circuit includes the electric terminal, the conductive sphere, the upper electrode plate, the electrostrictive element, the lower electrode plate, the piston, and the grounded casing. An electrostrictive hydraulic pressure generator characterized by comprising: 9. The electrostrictive hydraulic pressure generating device according to claim 5, wherein the initial compressive load adjusting means has an axial through hole, and there is a gap between the upper support member and the electrostrictive element. An upper electrode plate is supported between the lower support member and the electrostrictive element, and a part of the lower electrode plate extends to the piston. The voltage supply circuit is
The lead wire extends through the axial through hole of the initial compression load adjusting means and is connected to the upper electrode plate, the upper electrode plate, the electrostrictive element, the lower electrode plate, the piston, and the grounded casing. An electrostrictive hydraulic pressure generator characterized by comprising: 10. The electrostrictive hydraulic pressure generating device according to claim 9, wherein the self-aligning mechanism includes a conical recess formed on the lower surface of the lower support member and a conical recess formed on the upper surface of the piston. and a rigid conductive sphere disposed between the two recesses, and a portion of the lower electrode plate is in contact with the conductive rod. type hydraulic pressure generator. 11. The electrostrictive hydraulic pressure generating device according to any one of claims 1 to 10, wherein the columnar electrostrictive element is formed by laminating a plurality of discs of electrostrictive material. An electrostrictive hydraulic pressure generator characterized by: 12. An electrostrictive hydraulic pressure generating device according to any one of claims 1 to 6, wherein the casing is provided with a cooling oil inlet and a cooling oil outlet, An electrostrictive hydraulic pressure generator characterized in that an electrostrictive element can be cooled by introducing cooling oil into an internal space of a casing.