JP2010226802A - Ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor which generates an elliptical vibration by a vertical and twisted vibration mode by using only a single vibrator, rotates a rotor by the elliptical vibration, and transmits a rotational force to the axial direction. <P>SOLUTION: The ultrasonic motor 10 includes: a laminated piezoelectric element 11 whose cross section vertical to a center axis has a rectangle length ratio; a holder 25 which is fixed to a common node between the vertical primary resonance vibration and the twisted tertiary resonance vibration of the laminated piezoelectric element 11; a rotor part 26a which is rotatively driven by contacting with a friction contact member 12 fixed to the elliptical vibration generation face of the laminated piezoelectric element 11; a shaft-integrated rotor 26 composed of a shaft which axially transmits a rotational force of the rotor part 26a; a nut 27 which pushes and presses the rotor part 26a; and a case 30 which holds the laminated piezoelectric element 11 via a vibrator holder 25. Then, the vertical primary resonance vibration which elongates and contracts in the axial direction of the rotation of the laminated piezoelectric element 11 and the twisted tertiary resonance vibration with the rotational axis as a twisted axis are synthesized to generate the elliptical vibration, thus rotating the shaft-integrated rotor 26. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic motor that drives a driven body using ultrasonic vibration as a driving force source.

  For example, Patent Document 1 below proposes an ultrasonic motor that rotates a rotor by synthesizing longitudinal vibration and torsional vibration of a vibrator to generate elliptical vibration. FIG. 1 of Patent Document 1 below shows an exploded perspective view of the vibrator, and a plurality of plate-like shapes having holes between elastic bodies cut obliquely with respect to the vibrator axis direction. A vibrator having a laminated structure in which a piezoelectric element is sandwiched between two elastic members is used. And in Embodiment 1 of the following patent document 1, it pinches | interposes and fixes with the screw | thread which has the length which protrudes from an upper elastic member, In 2nd Embodiment, a screw part is comprised in the lower elastic member. Thus, a plate-like piezoelectric element is sandwiched and fixed.

JP-A-9-117168

  The ultrasonic motor described in the above-mentioned patent document 1 has a plate-like piezoelectric element that is superposed so that longitudinal and torsional vibration modes are simultaneously generated in the vibrator and are attached to the surface of the upper elastic member. An elliptical motion is generated in the wear material, and the rotor is pressed and rotated there. However, since the configuration of either embodiment is (i) a structure in which plate-like piezoelectric elements are stacked and sandwiched between elastic bodies, the configuration of the vibrator becomes complicated. (Ii) Upper elastic member Since the shaft extending from the shaft is only used as a part of the pressing mechanism for holding the rotor, the rotational force cannot be transmitted in the axial direction. In other words, there is a problem that it is difficult to use this ultrasonic motor for a device or the like in which the space in the outer circumferential direction of the rotor has no room.

  Therefore, the present invention has been made in view of the above circumstances, the purpose of which is to form an elliptical vibration combining a longitudinal and a torsional vibration mode with only a single vibrator, rotate the rotor by the elliptical vibration, An ultrasonic motor capable of transmitting a rotational force in an axial direction is provided.

  That is, the present invention corresponds to a common node of a vibrator composed of a single piezoelectric element having a rectangular length ratio in a cross section perpendicular to the central axis, and the longitudinal primary resonance vibration and torsional tertiary resonance vibration of the vibrator. A member for holding the vibrator fixed to the part, a rotating unit that is driven to rotate about a central axis that is in contact with the elliptical vibration generating surface of the vibrator and is orthogonal to the elliptical vibration generating surface of the vibrator, and the rotating unit A rotational force transmission member in which a rotational portion transmitting the rotational force in the axial direction is integrated and an elliptical vibration generating surface of the vibrator, and the rotational force generated by the elliptical vibration is frictional with the rotational force transmission member. A friction contact member that transmits by contact and a support hole that supports the rotated portion of the rotational force transmitting member are formed, and the rotational force transmitting member is attached to the vibrator while supporting the rotated portion of the rotational force transmitting member. A pressing member that presses the elliptical vibration generating surface; Forming a first hole for housing the vibrator, a second hole for housing the vibrator holding member, and a third hole for housing the pressing member; By combining a longitudinal primary resonance vibration that expands and contracts in the direction of the rotation axis of the vibrator and a torsional tertiary resonance vibration having the rotation axis as a torsion axis. The rotational force transmission member is formed and rotated.

  Further, the present invention corresponds to a common node of a vibrator composed of a single piezoelectric element having a rectangular length ratio in a cross section perpendicular to the central axis, and the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the vibrator. A member for holding the vibrator fixed to the part, a rotating unit that is driven to rotate about a central axis that is in contact with the elliptical vibration generating surface of the vibrator and is orthogonal to the elliptical vibration generating surface of the vibrator, and the rotating unit A rotational force transmission member in which a rotational portion transmitting the rotational force in the axial direction is integrated and an elliptical vibration generating surface of the vibrator, and the rotational force generated by the elliptical vibration is frictional with the rotational force transmission member. A state in which a friction contact member that transmits by contact, a hole that accommodates the vibrator, and a hole that accommodates the vibrator holding member are formed and the vibrator is held via the vibrator holding member The rotational portion of the rotational force transmitting member is A pressing member that presses against the circular vibration generating surface, a first hole that supports the rotated portion of the rotational force transmitting member, and a second hole that accommodates the pressing member are formed. A longitudinal primary resonance vibration that expands and contracts in the direction of the rotation axis of the vibrator and a torsional tertiary resonance vibration that uses the rotation axis as a torsion axis are provided. Thus, an elliptical vibration is formed to rotate the rotational force transmitting member.

  Furthermore, the present invention corresponds to a common node of a vibrator composed of a single piezoelectric element having a rectangular length ratio in a cross section perpendicular to the central axis, and the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the vibrator. A vibrator holding member fixed to a portion; a rotational force transmitting member that is driven to rotate about a central axis that is in contact with the elliptical vibration generating surface of the vibrator and is orthogonal to the elliptical vibration generating surface of the vibrator; A frictional contact member fixed to the elliptical vibration generating surface of the vibrator and transmitting the rotational force generated by the elliptical vibration by frictional contact with the rotational force transmitting member; and the rotational force transmitting member as the elliptical vibration generating surface of the vibrator A longitudinal primary resonance vibration that expands and contracts in the rotational axis direction of the vibrator and a torsional tertiary resonance vibration that uses the rotational axis as a torsion axis. By combining The formed and wherein the rotating the rotary force transmitting member.

  According to the present invention, an ultrasonic motor that forms an elliptical vibration combining a longitudinal mode and a torsional vibration mode with only a single vibrator and rotates the rotor by the elliptical vibration to transmit a rotational force in the axial direction. Can be provided.

It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 1st Embodiment of this invention. 1 is an assembly diagram of an ultrasonic motor according to a first embodiment of the present invention. 1 is a cross-sectional view of an ultrasonic motor according to a first embodiment of the present invention. 1A and 1B show a laminated piezoelectric element in a state where a frictional contact member is bonded in the ultrasonic motor 10 of FIG. 1, wherein FIG. 1A is an external perspective view, and FIG. 1 shows a configuration of a laminated piezoelectric element 11, (a) is a plan view seen from above, (b) is an exploded perspective view, (c) is a perspective view seen from the α direction of (a), (d). Is a view of the laminated piezoelectric element 11 as viewed from the γ direction of (a), (e) is a view of the laminated piezoelectric element 11 as viewed from the δ direction of (a), and (f) is an external view of the laminated piezoelectric element of (d). The figure which showed the state in which the electrode was attached, (g) is the figure which showed the state in which the external electrode was attached to the laminated piezoelectric element of (e), (h) was the external electrode in the laminated piezoelectric element of (d). The figure which showed the other example attached, (i) is the figure which showed the other example to which the external electrode was attached to the laminated piezoelectric element of (e). It is the figure which showed the example of arrangement | positioning of the cross finger electrode formed in the laminated piezoelectric element surface. FIG. 6 is a cross-sectional view including the polarization direction shown along the line BB ′ in FIG. 5B and perpendicular to the side surface. It is a figure for demonstrating the coincidence of the natural frequency of the multilayer piezoelectric element 11 used for the ultrasonic motor 10 of the 1st Embodiment of this invention. 8 represents the resonance frequency of each mode at various rectangular ratios where the side c of the vibrator 11 in FIG. 8 is constant and the horizontal axis is the length of the short side / the length of the long side (a / b). FIG. It is the perspective view which showed pins 33a-33d which support the laminated piezoelectric element 11 in the 2nd modification of the 1st Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 2nd modification of the 1st Embodiment of this invention. It is the perspective view which showed the pins 33c and 33d which support the laminated piezoelectric element 11 in the further another example of the 2nd modification of the 1st Embodiment of this invention. FIG. 10 is a sectional view of an ultrasonic motor according to still another example of the second modification of the first embodiment of the present invention, and is a detailed view of a portion into which a laminated piezoelectric element supported only by pins 33c and 33d is fitted. is there. _{(Please correct the hole 31b2 in the case 30 of FIG. 13 to 31b1)} It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 2nd Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 2nd Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 2nd Embodiment of this invention. It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 3rd Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 3rd Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 3rd Embodiment of this invention. It is an external appearance perspective view which shows the structure of the rotation contact member of the ultrasonic motor by the 1st modification of the 3rd Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 1st modification of the 3rd Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 1st modification of the 3rd Embodiment of this invention. The structure of the ultrasonic motor by the 4th Embodiment of this invention is shown, (a) is a disassembled perspective view, (b) is the perspective view which expanded and showed the shaft-integrated rotor of (a). It is an assembly drawing of the ultrasonic motor by the 4th Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 4th Embodiment of this invention. It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 5th Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 5th Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 5th Embodiment of this invention. It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 6th Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 6th Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 6th Embodiment of this invention. It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 7th Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 7th Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 7th Embodiment of this invention. It is a disassembled perspective view of the ultrasonic motor by the modification of the 7th Embodiment of this invention. FIG. 36 is an external perspective view showing a configuration of a lid portion of the case of FIG. It is an assembly drawing of the ultrasonic motor by the modification of the 7th Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the modification of the 7th Embodiment of this invention. It is a disassembled perspective view which shows the structure of the ultrasonic motor by the 8th Embodiment of this invention. It is an assembly drawing of the ultrasonic motor by the 8th Embodiment of this invention. It is sectional drawing of the ultrasonic motor by the 8th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is an exploded perspective view showing the configuration of the ultrasonic motor according to the first embodiment of the present invention. FIG. 2 is an assembly diagram of the ultrasonic motor according to the first embodiment, and FIG. 3 is a cross-sectional view of the ultrasonic motor according to the first embodiment.

  The ultrasonic motor 10 includes a laminated piezoelectric element (vibrator) 11, a friction contact member 12 (12a, 12b), a vibrator holder 25, a shaft-integrated rotor 26, a nut 27, and a case 30. It consists of a total of 6 parts.

  The laminated piezoelectric element 11 is formed of a single-structure element in which a cross section perpendicular to the central axis O of the ultrasonic motor 10 has a rectangular length ratio. The frictional contact member 12 (12a, 12b) is fixed to an elliptical vibration generating surface formed by combining the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the multilayer piezoelectric element 11. The friction contact member 12 uses engineering plastic (PPS or the like) as a material. Further, the frictional contact member 12 is an arc-shaped component having the central axis O of the ultrasonic motor 10 as an axis, and is bonded and fixed to a surface orthogonal to the longitudinal direction of the laminated piezoelectric element 11.

  The vibrator holder 25 which is a vibrator holding member is fixed to a portion corresponding to a common node of the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the multilayer piezoelectric element 11, and is disposed inside the U-shape. The laminated piezoelectric element 11 is held and fixed so as to be sandwiched from the side surface by the recessed portion. The vibrator holder 25 is made of an alumite-treated aluminum material or an insulation-treated metal material. When the laminated piezoelectric element 11 is assembled in the case 30, the central axis of the laminated piezoelectric element 11 exceeds the center axis. The shape coincides with the central axis O of the sonic motor 10.

  The shaft-integrated rotor 26, which is a rotational force transmitting member, has a rotor portion 26a that is driven to rotate by being pressed by the frictional contact member 12, and a shaft portion 26b that transmits the rotational force of the rotor portion 26a. It becomes the composition. The rotor portion 26a is formed on a surface orthogonal to the central axis O, and the shaft portion 26b is formed to extend in the direction of the central axis O from the rotor portion 26a. The tip of the shaft portion 26b has a shape that can fix a transmission component such as a gear, a pulley, and a coupling (for example, a single-sided D-cut shape as shown in FIGS. There is).

  A shaft hole that can be rotated and supported by inserting the shaft portion 26b of the shaft-integrated rotor 26 into the central portion of the nut 27 (the diameter of the shaft portion 26b of the shaft-integrated rotor 26 has a fitting relationship with the shaft hole. (Diameter dimension) is formed. The shape of the outer surface of the nut 27 is such that the center of the shaft hole 28 through which the shaft portion 26 b of the shaft-integrated rotor 26 passes when the nut 27 is inserted and fixed in the fitting hole 31 of the case 30 is the central axis of the ultrasonic motor 10. It has a fitting shape (circular shape) so as to coincide with O. The nut 27 serves as a pressing member to contact the rotor portion 26 a and press the rotor portion 26 a against the friction contact member 12 while supporting the rotation of the shaft portion 26 b of the shaft-integrated rotor 26.

  The case 30 as a holding member has a cylindrical shape, and the rotor portion 26a of the shaft-integrated rotor 26 is pressed against the friction contact member 12 while holding the laminated piezoelectric element 11 in the fitting hole 31 inside the case 30. The nut 27 is adhered and fixed in the state. The fitting hole 31 formed in the case 30 is formed with a hole 31 b into which the vibrator holder 15 fixed to the laminated piezoelectric element 11 is fitted. Further, a hole 31a into which the nut 27 is fitted is formed in the upper portion of the hole 31b. A hole 31c that is slightly larger than the outer dimension of the laminated piezoelectric element 11 is formed below the hole 31b. Thereby, the laminated piezoelectric element 11 is arranged so that portions other than the vibrator holder 25 and the frictional contact member 12 do not contact the fitting hole 31 of the case 30.

  These fitting holes 31 (holes 31 a, 31 b, 31 c) are arranged such that when the laminated piezoelectric element 11 and the nut 27 are assembled inside the case 30, the axis center of the laminated piezoelectric element 11 and the nut 27 is the ultrasonic motor 10. Are coaxially processed so as to coincide with the axial center O.

  The shaft-integrated rotor 26, the nut 27, and the case 30 are all made of a metal material such as stainless steel or aluminum.

  Next, details of the laminated piezoelectric element 11 will be described with reference to FIGS. 4 to 9.

  4A and 4B show the laminated piezoelectric element in a state where the friction contact member is bonded, where FIG. 4A is an external perspective view, and FIG. 4B is a top view. 5A and 5B show the structure of the laminated piezoelectric element 11. FIG. 5A is a plan view seen from above, FIG. 5B is an exploded perspective view, and FIG. 5C is a perspective seen from the α direction of FIG. (D) is a view of the laminated piezoelectric element 11 as viewed from the γ direction of (a), (e) is a view of the laminated piezoelectric element 11 as viewed from the δ direction of (a), and (f) is a view of (d). The figure which showed the state where the external electrode was attached to the laminated piezoelectric element, (g) is the figure which showed the state where the external electrode was attached to the laminated piezoelectric element of (e), (h) is the laminated piezoelectric element of (d). The figure which showed the other example in which the external electrode was attached to the element, (i) is the figure which showed the other example in which the external electrode was attached to the laminated piezoelectric element of (e).

  The laminated piezoelectric element 11 of the ultrasonic motor 10 is configured by laminating a plurality of piezoelectric elements.

  The friction contact members 12 a and 12 b are bonded to a surface orthogonal to the longitudinal direction of the laminated piezoelectric element 11 so as to come into contact with the rotor portion 26 a of the shaft-integrated rotor 26. However, if a convex part is provided on the same track as the friction contact members 12a and 12b on the lower surface of the rotor portion 26a, the friction contact members 12a and 12b are not necessarily required. In this case, the convex portion is made of the same material as the friction contact members 12a and 12b. In FIG. 4A, four external electrodes 13 are provided on the left side of the drawing, and four external electrodes 13 are also provided on the right side although not shown.

  Next, the internal electrode configuration of the laminated piezoelectric element 11 will be described.

  The laminated piezoelectric element 11 is configured by laminating thin piezoelectric sheets such as lead zirconate titanate (hereinafter referred to as PZT) on which a predetermined internal electrode pattern is formed.

  FIG. 5A is a view of the laminated piezoelectric element 11 as viewed from above, and side surfaces in four directions are indicated by arrows, α, β, γ, and δ, respectively. FIG. 5B shows an example of a piezoelectric sheet and internal electrode patterns.

  Each of the piezoelectric sheets is made of a PZT material having a thickness of about 10 μm to 100 μm. The piezoelectric sheet 1 (hereinafter referred to as a piezoelectric sheet (1)) 15a has an internal electrode pattern 1 (hereinafter referred to as an internal electrode pattern (1)). An internal electrode pattern 2 (hereinafter referred to as internal electrode pattern (2)) 16b is printed on the piezoelectric sheet 2 (hereinafter referred to as piezoelectric sheet (2)) 15b. On the piezoelectric sheet (1) 15a, as shown in the figure, the interdigitated internal electrodes are printed at three locations as the internal electrode pattern (1) 16a.

  The material of the interdigitated internal electrode is made of, for example, a silver palladium alloy, the width is set to a range of about 0.1 mm to 1 mm, and the insulation width therebetween is also set to a range of about 0.1 mm to 1 mm. Moreover, thickness is 2-3 micrometers, for example.

  Here, the cross finger electrode refers to an electrode in which a + phase electrode and a-phase electrode are alternately combined. In FIG. 5 (b), the cross finger electrodes have two pairs of cross finger electrodes for the sake of easy viewing. However, in order to make the area as large as possible in the plane, in FIG. As shown, more pairs of crossed finger electrodes may be configured to be formed on one side of the plane. In the present invention, the cross finger electrode is referred to as a cross finger internal electrode because it is provided inside the laminated piezoelectric element.

In FIG. 5B, the cross finger electrode has an angle formed by the height direction (indicated by a broken line) and the finger direction of the cross finger internal electrode. Finger electrode)
0 <θ <π / 2
And Since the polarization direction ε is a direction orthogonal to the direction of the fingers of the cross finger electrode, as indicated by the broken line in the figure,
0 <| ε | <π / 2
It is.

Also, the angle formed by the second cross finger electrode (second cross finger electrode) from the top of the figure is φ, as shown in the figure,
π / 2 <φ <π
It has become.

  The second cross finger electrode is electrically connected to the first cross finger electrode in parallel, and a part of the second cross finger electrode extends to the end of the piezoelectric sheet. These cross finger electrodes function as drive cross finger electrodes. The angles θ and φ may be set in the opposite range.

As shown in the figure, the angle formed by the third cross finger electrode (third cross finger electrode) from the top in the figure is ψ, which is a value other than 0, π / 2, and π. In form,
0 <ψ <π / 2
It is said. The third cross finger electrode has a function as a vibration detection electrode.

  The n piezoelectric sheets (1) 15a on which the internal electrode patterns (1) 16a are printed are stacked, and then the piezoelectric sheets (2) 15b on which the n internal electrode patterns (2) 16b are similarly printed. Laminated. The difference between the piezoelectric sheet (2) 15b and the piezoelectric sheet (1) 15a is the position of the electrode extending to the end as shown in FIG. 5 (b). The configuration and position of the interdigital electrode itself are exactly the same. Finally, a piezoelectric sheet 3 (hereinafter referred to as a piezoelectric sheet (3)) 15c on which no electrodes are printed is laminated on the piezoelectric sheet (2) 15b.

  Therefore, the total number of laminated piezoelectric elements 11 is 2n + 1, which is an odd number.

  FIG. 5C is a view of the multilayer piezoelectric element 11 as viewed from the front.

As will be described later, in this embodiment, torsional tertiary vibration and longitudinal primary vibration are used. The central portion of the upper cross finger electrode is provided in the vicinity of the upper node position 23 ₂ of the torsional tertiary vibration, and the central portion of the central cross finger electrode is in the vicinity of the central node position of the torsional tertiary vibration and the longitudinal primary vibration. provided node position 23 ₁ near the central portion of the lower interdigital electrode is provided on the lower section position 23 ₃ near the torsional tertiary vibration.

5D and 5F are views of the multilayer piezoelectric element 11 as viewed from the γ direction of FIG. 5A. In FIG. 5B, the upper cross finger electrode and the central cross finger electrode 17a _{1 of} the internal electrode pattern (1) 16a are extended to the end in the left direction to form the internal electrode exposed portion 21a _1. ing. The internal electrode exposed portion 21a ₁ is joined to the external electrode A + phase 13a ₁ . Similarly, in FIG. 5B, the upper cross finger electrode and the central cross finger electrode 17b _{1 of} the internal electrode pattern (2) 16b are extended to the end in the left direction to expose the internal electrode exposed portion 21b _1. Is formed. The internal electrode exposed portion 21b ₁ is joined to the external electrode B + phase 13b ₁ .

Further, the lower cross finger electrode 18a _{1 of} the internal electrode pattern (1) 16a is extended to the end in the left direction to form the internal electrode exposed portion 22a ₁ . The internal electrode exposed portion 22a ₁ is joined to the external electrode C + phase 13C ₁ . Further, the lower cross finger electrode 18b _{1 of} the internal electrode pattern (2) 16b extends to the end in the left direction to form an internal electrode exposed portion 22b ₁ . The internal electrode exposed portion 22b ₁ is joined to the external electrode D + phase 13d ₁ .

FIGS. 5E and 5G are views of the multilayer piezoelectric element 11 viewed from the δ direction of FIG. 5A. In FIG. 5B, the upper cross finger electrode and the central cross finger electrode 17a _{2 of} the internal electrode pattern (1) 16a are extended to the end in the right direction to form the internal electrode exposed portion 21a _2. ing. The internal electrode exposed portion 21a ₂ is joined to the external electrode A-phase 13a ₂ . Similarly, in FIG. 5B, the upper cross finger electrode and the central cross finger electrode 17b _{2 of} the internal electrode pattern (2) 16b are extended to the right end to the internal electrode exposed portion 21b _2. Is formed. The internal electrode exposed portion 21b ₂ is joined to the external electrode B-phase 13b ₂ .

Further, the lower cross finger electrode 18a _{2 of} the internal electrode pattern (1) 16a is extended to the end in the right direction to form an internal electrode exposed portion 22a ₂ . The internal electrode exposed portion 22a ₂ is joined to the external electrode C-phase 13C ₂ . Further, the lower cross finger electrode 18b _{2 of} the internal electrode pattern (2) 16b is extended to the end in the right direction to form an internal electrode exposed portion 22b ₂ . The internal electrode exposed portion 22b ₂ is joined to the external electrode D-phase 13d ₂ .

  In this way, if the electrode pattern is designed to provide equivalent vibration characteristics with a cross section cut by a virtual center line as a boundary, the position of the external electrode is as shown in FIGS. 5 (f) and 5 (g). Even if they are arranged at different positions, the vibration characteristics are not changed, so that they are substantially symmetrical.

  Next, a method for producing the multilayer piezoelectric element 11 will be described.

Plural sheets of internal electrode pattern (1) 16a printed on piezoelectric sheet (1) 15a before firing, and plural sheets of internal electrode pattern (2) 16b printed on piezoelectric sheet (2) 15b. A sheet is prepared. First, after n sheets of piezoelectric sheets (1) 15a are stacked, n sheets of piezoelectric sheets (2) 15b are stacked, and further one sheet of piezoelectric sheet (3) 15c with no internal electrodes printed thereon is stacked. . Then, after being pressed and cut into a predetermined size, firing is performed at a predetermined temperature. Thereafter, the external electrodes 13a ₁ , 13a ₂ , 13b ₁ , 13b ₂ , 13c ₁ , 13c ₂ , 13d ₁ and 13d ₂ are printed and baked at predetermined positions.

The external electrode is not limited to the example described above. In the above-described example, the internal electrodes exposed portions 21a ₁ , 21a ₂ , 21b ₁ , 21b ₂ , 22a ₁ , 22a ₂ , 22b ₁ , 22b ₂ are substantially the same width as the external electrodes 13a ₁ , 13a ₂ , 13b _1. , 13b ₂ , 13c ₁ , 13c ₂ , 13d ₁ , 13d ₂ are provided. However, for example, as shown in FIGS. 5 (h) and 5 (i), the laminated piezoelectric element 11 may be provided over the entire short side direction.

  FIG. 5H is a view of the multilayer piezoelectric element 11 viewed from the γ direction of FIG. 5A, and FIG. 5I is a view of the multilayer piezoelectric element 11 viewed from the δ direction of FIG. 5A. is there.

That is, for the internal electrode exposed portions 21a ₁ , 21a ₂ , 21b ₁ , 21b ₂ , 22a ₁ , 22a ₂ , 22b ₁ , 22b ₂ , the external electrodes 13a ₃ , 13a ₄ , 13b including the internal electrode exposed portions are used. ₃ , 13 b ₄ , 13 c ₃ , 13 c ₄ , 13 d ₃ , and 13 d ₄ are provided to be joined.

  Next, polarization will be described with reference to FIG.

  FIG. 7 is a cross-sectional view including the polarization direction shown along the line BB ′ in FIG. 5B and perpendicular to the side surface.

  In FIG. 7, the polarization vector indicated by the arrow P is polarized toward the other pole (−) with a slight bulge from the pole (+) on one side. This vector also coincides with the electric field vector. Further, the distance between adjacent internal electrodes is, for example, 300 μm, and the distance between the + and − poles (in the thickness direction of the piezoelectric sheet) is, for example, 100 μm.

  Next, the operation of the multilayer piezoelectric element 11 will be described.

  As shown in FIG. 8A, the multilayer piezoelectric element 11 has a rectangular parallelepiped shape, and the dimensions of the respective sides a, b, and c are set to appropriate values, so that the resonance frequency of the longitudinal primary vibration mode is obtained. And the torsional secondary vibration mode or the torsional tertiary vibration mode are made to substantially coincide with each other.

8B shows the torsional primary vibration mode, FIG. 8C shows the longitudinal primary vibration mode, FIG. 8D shows the torsional secondary vibration mode, and FIG. 8E shows the torsional tertiary vibration mode. It is the figure which showed the vibration state schematically. In addition, the solid line indicates the shape of the multilayer piezoelectric element 11 before vibration, and the broken line indicates the shape of the multilayer piezoelectric element 11 after vibration. In the figure, 23 ₁ , 23 ₂ , 23 ₃ , 23 ₄ , and 23 ₅ are positions corresponding to vibration nodes of the laminated piezoelectric element 11, and 23 ₄ and 23 ₅ are upper node positions of torsional secondary vibration, This is the lower node position of the torsional secondary vibration.

  Here, each side a, b, and c of the rectangular parallelepiped is defined. Now, let the direction of the side c be the direction of vibration in the longitudinal primary vibration mode and the axial direction of torsion of torsional vibration. Further, the direction orthogonal to the side c is defined as the direction of the side a and the direction of the side b. Here, the length ratio of each rectangular cross section perpendicular to the axis parallel to the side c along the side c is a <b <c, a is referred to as a short side, and b is referred to as a long side. This will be described below.

  FIG. 9 is a diagram showing the resonance frequency of each mode in various rectangular ratios in which the side c is constant and the horizontal axis is the length of the short side / the length of the long side (a / b). is there. As can be seen from the figure, when a / b is changed, the resonance frequency of the longitudinal primary vibration mode does not depend on a / b and takes a substantially constant value. However, the resonance frequency of torsional vibration monotonously increases as the a / b value approaches 1. The resonance frequency of the torsional primary vibration mode has no condition that matches the resonance frequency of the longitudinal primary vibration mode regardless of the value of a / b.

  However, it is clear that the resonance frequency of the torsional secondary vibration mode matches when the a / b value is around 0.6. Further, it is clear that the resonance frequency of the torsional tertiary vibration mode matches when the a / b value is around 0.3. Therefore, in this embodiment, each dimension of the vibrator 11 is set so that a / b is approximately 0.3.

  In the present embodiment, the dimension of each side a × b × c of the vibrator 11 is, for example, 3 × 10 × 20 mm.

  As shown in FIG. 5 (b), the first layer which is the outermost layer of the piezoelectric sheet (1) and the outermost layer piezoelectric sheet (2) which is laminated at the end of the piezoelectric sheet (2) are used for the main lamination. A method for driving the piezoelectric element 11 will be described.

  First, the operation of the laminated piezoelectric element 11 using the driving cross finger electrode will be described.

  First, an alternating voltage corresponding to the resonance frequency of longitudinal primary vibration or torsional tertiary vibration is applied to the A phase (A + phase, A− phase). In FIG. 5B, the force generated in the vicinity of the upper cross finger electrode by the inverse piezoelectric effect at that time is displayed as a vector.

  The force F shown in FIG. 5B is an alternating force, and when the force is vector-decomposed, F1 and F2 are obtained. As is clear from the figure, the force F1 is a force that excites longitudinal vibration. Further, the force F2 is a force that generates a torsional tertiary vibration, as is apparent from the drawing.

  Next, an alternating voltage having the same frequency as that of the A phase is also applied to the B phase (B + phase, B− phase). In FIG. 5B, the force generated in the vicinity of the upper cross finger electrode of the piezoelectric sheet (2) 15b positioned on the outermost surface at that time is displayed as a vector.

  The force F ′ shown in FIG. 5B is an alternating force, and F1 ′ and F2 ′ are obtained by vector decomposition of the force. The force F1 ′ is a force that excites the longitudinal vibration as is apparent from the figure. Further, as apparent from the figure, the force F2 'becomes a force that generates a torsional tertiary vibration.

  Next, only the power generated when an alternating voltage having the same phase is applied to the A phase and the B phase at the same time will be considered. In this case, as shown in FIG. 5B, the forces F2 and F2 'cancel each other, and no torsional tertiary vibration is generated, and only longitudinal primary vibration is generated.

  Furthermore, when an alternating voltage having the above-mentioned frequency of opposite phase (phase difference π) is simultaneously applied to the A phase and the B phase, the forces F1 and F1 ′ cancel each other, no longitudinal primary vibration occurs, and the torsional tertiary Only vibration will occur.

  Next, consider a case where a phase difference between 0 and π is simultaneously given to the A phase and the B phase. In this case, the longitudinal primary vibration and the torsional tertiary vibration occur simultaneously, and these vibrations are synthesized. At this time, as shown in FIG. 4, the rotor portion 26 a is rotated in the clockwise direction (CW direction) or the counterclockwise direction (CCW direction) so as to rotate to the adhesion position of the frictional contact members 12 a and 12 b of the multilayer piezoelectric element 11. Direction) elliptical vibrations are formed. When elliptical vibration is generated at the positions of the frictional contact members 12a and 12b of the laminated piezoelectric element 11, the rotor part 26a pressed by the nut 27 uses the shaft part 26b as a rotation axis (or a central axis) and the elliptical vibration is generated. According to the direction of rotation, the rotation operation is performed in the clockwise direction (CW direction) or the counterclockwise direction (CCW direction).

  In addition, since the direction of twist is reversed about the remaining pair of driving interdigital electrodes, the direction of the interdigital electrodes is set to be an obtuse angle. Since the driving principle is the same, the description is omitted.

  Next, the operation of the lower vibration detection cross finger electrode shown in FIG. 5B will be described.

  When longitudinal primary vibration or torsional tertiary vibration occurs, electric charges are generated on the surface of the interdigitated electrode due to the piezoelectric effect. The charge is observed as a voltage of the C phase (between the C + phase and the C− phase) or a voltage of the D phase (between the D + phase and the D− phase). In the operation with the driving cross-finger electrodes, force is generated by the driving voltage due to the above-described reverse piezoelectric effect, but on the contrary, charges or voltages are generated by mechanical distortion.

  Therefore, when only longitudinal primary vibration is occurring, the C phase and the D phase are connected in parallel in order (the C + phase and the D + phase are connected, and the C− phase and the D− phase are connected: defined as a parallel forward connection phase). As a result, a signal proportional to the magnitude and phase of the longitudinal primary vibration is obtained as the voltage generated in the meantime. However, when the C phase and the D phase are reversely connected in parallel (the C + phase and the D− phase are connected and the C− phase and the D + phase are connected: defined as a parallel reverse connection phase), no signal is output.

  On the other hand, when only the torsional tertiary vibration occurs, the C phase and D phase are connected in reverse (C + phase and D− phase are connected, and C− phase and D + phase are connected). As the voltage, a signal proportional to the magnitude and phase of the torsional tertiary vibration is obtained. However, when the C phase and the D phase are connected in parallel in order (the C + phase and the D + phase are connected, and the C− phase and the D− phase are connected), no signal is output.

  Therefore, by selecting the connection between the C phase and the D phase, it is possible to independently detect the longitudinal primary vibration or the torsional tertiary vibration.

  Next, a method of driving a motor using such a vibration detection phase (C phase, D phase) will be described.

  The phase difference between the phase of the A-phase or B-phase signal that is the driving phase and the phase of the vibration detection phase (for example, the C-phase and the D-phase are reversely connected in parallel) is predetermined during the resonance frequency operation of the torsional tertiary vibration It is known to take the value Ω. Therefore, in this case, by adjusting the frequency so that the phase difference between the drive phase and the detection phase is always Ω, the temperature is increased due to the heat generated by the motor itself, the resonance frequency changes due to changes in the ambient temperature, and the load. Even if there is a change in the resonance frequency due to fluctuations, it can always be driven near the torsional third-order resonance frequency. Therefore, it is possible to drive efficiently at always the optimum frequency. This is also possible with the same concept when driving near the longitudinal primary resonance frequency.

  As shown in FIGS. 2 and 3, the vibrator holder 25 has a portion corresponding to a common node of the longitudinal primary resonance vibration and the torsional tertiary resonance vibration on the surface in the longitudinal direction of the multilayered piezoelectric element 11 configured as described above. Two (25a, 25b) are bonded and fixed. Further, as described above, the frictional contact member 12 (12a, 12b) is bonded and fixed to the surface orthogonal to the longitudinal direction of the laminated piezoelectric element 11.

  The laminated piezoelectric element 11 to which the two members of the vibrator holder 25 and the frictional contact member 12 are bonded and fixed is fitted into the case 30 via the vibrator holder 25. At this time, it is positioned and fixed so that the central axis of the case 30 and the central axis of the laminated piezoelectric element 11 coincide. The shaft portion 26b of the shaft-integrated rotor 26 is inserted into the shaft hole 28 of the nut 27, and the nut 27 is inserted into the case 30 in this state.

  The shaft-integrated rotor 26 is pressed in the axial direction (elliptical vibration generating surface side) by a nut 27, and the rotor portion 26 a comes into contact with the elliptical vibration generating surface of the friction contact member 12 with a rotatable pressing force. Yes. The nut 27 is bonded and fixed to the case 30 while the shaft-integrated rotor 26 is pressed.

  As described above, according to the first embodiment, the vibrator can be configured by a single laminated piezoelectric element, and the contact surface of the frictional contact member is vertically 1 in the direction of rotating the rotor portion of the shaft-integrated rotor. An elliptical vibration formed by the combination of the secondary resonance vibration and the torsional tertiary resonance vibration is generated. And when a rotor part rotates, the shaft part united coaxially will rotate and a rotational force will be transmitted to an axial direction. Therefore, an elliptical vibration combining the longitudinal and torsional vibration modes can be formed with only a single vibrator, and the rotational force can be transmitted in the axial direction by rotating the rotor by the elliptical vibration.

(First modification of the first embodiment)
Next, a first modification of the first embodiment of the present invention will be described.

  In the configuration of the first embodiment described above, the outer shape of the nut 27 and the fitting hole 31 for fitting the nut of the case 30 are circular, but this is not restrictive. For example, when the nut 27 is inserted and fixed in the case 31, the center of the hole through which the shaft portion 26b of the shaft-integrated rotor 26 is inserted coincides with the central axis of the ultrasonic motor 10, and an appropriate pressing force is applied to the rotor portion 26a. If it can be added, the shape can be changed to a shape other than a circle (for example, a polygonal shape such as a triangle, a quadrangle, or a five stroke shape not shown). Furthermore, the shape of the case is not limited to a cylindrical shape.

  According to the first modification of the first embodiment, the degree of freedom of the fitting hole in the case that houses the laminated piezoelectric element is increased.

(Second modification of the first embodiment)
In the first embodiment described above, the vibrator holder has a U-shape. However, as long as the laminated piezoelectric element can be positioned in the case, a pin is used as shown in FIGS. You can also

  FIG. 10 is a perspective view showing pins 33a to 33d for supporting the laminated piezoelectric element 11 in the second modification of the first embodiment of the present invention, and FIG. 11 is a second modification of the first embodiment. It is an assembly drawing of the ultrasonic motor by an example.

  Holes are made in the four surfaces of the portion to be the node of the laminated piezoelectric element 11 after firing, and pins 33a to 33d (33d not shown) are inserted. Then, the pins 33a to 33d are fitted into the case so as to be in contact with the wall of the fitting hole 31b of the vibrator holder 25 shown in FIGS. Then, as in the case where the U-shaped transducer holder 25 is used, the laminated piezoelectric element 11 can be positioned so as to come to the center position of the case 30.

  With such a structure, there is an advantage that the shape of the vibrator holder can be simplified and the labor of bonding is eliminated.

  In the second modification, the pins 33a to 33d have been described as being inserted into the laminated piezoelectric element 11 by holes, but the present invention is not limited to this and may be fixed by adhesion. .

  Furthermore, the number of pins is not limited to four as long as two pins at least facing each other are provided.

For example, as shown in FIG. 12, two pins 33c and 33d are attached to the long side surface of the multilayer piezoelectric element 11 (the surface formed by the sides b and c in FIG. 8). Then, as shown in FIG. 13, it is fitted into the hole 31 b ₁ in the case 30. Then, similarly to the case of four pins, the laminated piezoelectric element 11 can be positioned so as to come to the center position of the case 30.

  Of course, the mounting position of the two pins may be the surface on the short side of the multilayer piezoelectric element 11 (the surface constituted by the sides a and c in FIG. 8). In that case, the position of the pin insertion hole shown in FIG. 13 is also changed to the short side.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the embodiment described below, the basic configuration of the ultrasonic motor of the first embodiment described above is the same as that of the first embodiment described above. The same reference numerals are assigned to the same parts, illustration and description thereof are omitted, and only different parts will be described.

  FIG. 14 is an exploded perspective view showing the configuration of the ultrasonic motor according to the second embodiment of the present invention. FIG. 15 is an assembly diagram of the ultrasonic motor according to the second embodiment, and FIG. 16 is a cross-sectional view of the ultrasonic motor according to the second embodiment.

  As shown in FIGS. 14 to 16, the ultrasonic motor 10 a according to the second embodiment includes a fitting portion 31 a between the outer peripheral surface of the nut 27 a and the nut 27 a of the fitting hole 31 a in the case 30. In addition, a screw thread (a screw portion 27a1 on the outer peripheral surface of the nut 27a and a screw portion 31d on the fitting portion 31a) is formed. Therefore, the nut 27a is fixed to the case 30 by being screwed to the fitting portion 31d.

  The other components are the same as those in the first embodiment described above, and a description thereof will be omitted.

  As described above, according to the second embodiment, the operation of the ultrasonic motor 10a is the same as that of the first embodiment described above, but the case 30 and the nut 27 can be fixed with screws. There is no need to bond in the state. Further, the nut 27 can be easily pressed against the rotor portion 26a. Furthermore, when an internal component such as a laminated piezoelectric element breaks down, the nut 27 can be removed from the case 30 simply by loosening the screw, so that the ultrasonic motor 10a can be easily disassembled.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS.

  FIG. 17 is an exploded perspective view showing a configuration of an ultrasonic motor according to the third embodiment of the present invention. FIG. 18 is an assembly diagram of the ultrasonic motor according to the third embodiment, and FIG. 19 is a cross-sectional view of the ultrasonic motor according to the third embodiment.

  As shown in FIGS. 17 to 19, the ultrasonic motor 10b according to the third embodiment has a surface between the nut 27 and the rotor portion 26a, as compared with the first embodiment described above. A smooth annular contact member 35 is interposed. That is, the shaft portion 26 b of the shaft-integrated rotor 26 is inserted into the opening 35 a provided at the center of the rotary contact member 35 and the shaft hole 28 of the nut 27. The rotary contact member 35 is constituted by, for example, a washer made of fluororesin (Teflon (registered trademark)), and the friction coefficient is smaller than the surface of the nut 27 facing the rotor portion 26a.

  The other components are the same as those in the first and second embodiments described above, and a description thereof will be omitted.

  As described above, according to the third embodiment, the operation of the ultrasonic motor 10b is the same as that of the first and second embodiments described above, but the rotary contact member 35 is provided between the nut 27 and the rotor portion 26a. Therefore, the friction coefficient between the nut 27 and the rotor portion 26a is reduced. Therefore, the rotational accuracy of the rotor part 26a is improved even when compared with the configuration of the first embodiment described above in which the same pressure is applied.

(First Modification of Third Embodiment)
As described above, in the third embodiment, the rotation contact member 35 is interposed between the nut 27 and the rotor portion 26a to reduce the friction coefficient of the rotation contact member 35. However, if the surface of the rotating contact member 35 is processed, the friction coefficient can be further reduced.

  FIG. 20 is an external perspective view showing the configuration of the rotary contact member of the ultrasonic motor according to the first modification of the third embodiment of the present invention. FIG. 21 is an assembly diagram of an ultrasonic motor according to a first modification of the third embodiment, and FIG. 22 is a cross-sectional view of the ultrasonic motor according to the first modification of the third embodiment.

As shown in FIGS. 20 to 22, rotating contact member 35 ₁ of the first modification of the third embodiment, the portion where the rotor portion 26a corresponds to the position in contact with the frictional contact member 12a, 12b The convex portions 35 ₁ b and 35 ₁ c are continuously formed. The convex portion 35 ₁ c is formed on the rotation contact member 35 ₁ on the opposite side of the convex portion 35 ₁ b. Incidentally, 35 ₁ a is an opening into which the shaft portion 26b of the shaft-integrated rotor 26 is inserted.

  If comprised in this way, since the contact of the part which is not related to rotation is lose | eliminated (a contact area reduces), a rotation precision improves further.

  In the first modification, the example in which the convex portion is provided on the rotary contact member is shown, but the present invention is not limited to this. For example, a protrusion may be provided on the nut 27 or the rotor part 26a as long as the part corresponds to the position in contact with the frictional contact members 12a and 12b. Furthermore, a coating such as Teflon (registered trademark) processing may be applied to the convex portion.

(Second Modification of Third Embodiment 3)
In the third embodiment described above, a fluororesin washer is configured as the rotating contact member 35 between the nut 27 and the rotor portion 26a, but the rotating contact member is not limited to this. For example, if the friction coefficient is very low, although not shown, a solid lubricant such as molybdenum disulfide can be used instead of the rotating contact member.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS.

  FIG. 23 shows a configuration of an ultrasonic motor according to a fourth embodiment of the present invention, in which (a) is an exploded perspective view, and (b) is an enlarged perspective view of the shaft-integrated rotor of (a). FIG. FIG. 24 is an assembly diagram of the ultrasonic motor according to the fourth embodiment, and FIG. 25 is a cross-sectional view of the ultrasonic motor according to the fourth embodiment.

As shown in FIG. 23 (b), a continuous groove 26 c concentrically with the central axis O is formed on the surface of the rotor portion 26 a ₁ of the shaft-integrated rotor 26 that faces the nut 27. As shown in FIG. 25, the groove portion 26c is formed in a portion corresponding to a position where the rotor portion 26a contacts the frictional contact members 12a and 12b. A plurality of balls (rolling members used for ball bearings) 37 are laid in the groove 26c.

  Other components are the same as those in the first to third embodiments described above, and thus the description thereof is omitted.

  As described above, according to the fourth embodiment, the operation of the ultrasonic motor 10c is the same as that of the first to third embodiments described above, but a plurality of spheres are provided between the nut 27 and the rotor portion 26a. (Rolling member used for ball bearing) 37 is interposed. Thereby, since the nut 27 and the rotor part 26a rotate while making point contact with the ball 37, the contact area at the time of rotation becomes very small as compared with the configurations of the first to third embodiments described above.

  Further, when the rotor portion 26a rotates, the sphere 37 rotates while circulating, so that the rotational accuracy of the rotor portion 26a is remarkably improved as compared with the configurations of the first to third embodiments.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIGS.

  FIG. 26 is an exploded perspective view showing the configuration of the ultrasonic motor according to the fifth embodiment of the present invention. FIG. 27 is an assembly diagram of the ultrasonic motor according to the fifth embodiment, and FIG. 28 is a cross-sectional view of the ultrasonic motor according to the fifth embodiment.

  As shown in FIGS. 26 to 28, the ultrasonic motor 10d in the fifth embodiment is different from the first embodiment described above in that it is a rolling bearing between the nut 27 and the shaft portion 26b. 38a and 38b are added and comprised. Accordingly, holes 28a and 28b for press-fitting the rolling bearings 38a and 38b are formed at both ends of the shaft hole 28 of the nut 27.

  The other components are the same as those in the first to fourth embodiments described above, and a description thereof will be omitted.

  As described above, according to the fifth embodiment, the operation of the ultrasonic motor 10d is the same as that of the first to fourth embodiments described above, but the rolling bearing 38a, between the nut 27 and the shaft portion 26b, Since 38b is configured, the shaft runout or the like of the shaft portion 26b can be suppressed as compared with the configuration rotating by frictional contact in the first embodiment described above. Therefore, the rotation accuracy of the rotor part 26a is improved.

  In the fifth embodiment, the configuration using two rolling bearings has been described. However, the present invention is not limited to this, and there may be one rolling bearing or three or more rolling bearings.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS.

  FIG. 29 is an exploded perspective view showing the configuration of the ultrasonic motor according to the sixth embodiment of the present invention. FIG. 30 is an assembly diagram of the ultrasonic motor according to the sixth embodiment, and FIG. 31 is a cross-sectional view of the ultrasonic motor according to the sixth embodiment.

  As shown in FIGS. 29 to 31, the ultrasonic motor 10e according to the sixth embodiment is different from the configuration of the first embodiment described above in that the case is a boundary between the fitting hole of the vibrator holder 25. The upper and lower parts are divided into two.

  That is, the case according to the sixth embodiment is configured to include an upper case 40 and a lower case 42 and is fastened by a case fastening screw 45. A fitting hole 41 for fixing the nut 27 is formed in the upper case 40 in the same manner as the case 30 described above. On the other hand, a fitting hole 43 for fitting the vibrator holder 25 is formed in the lower case 42. The fitting hole 43 is basically the same as the fitting hole 31b of the case 30 of the first embodiment. Further, a hole 44 that is slightly larger than the outer dimension of the multilayer piezoelectric element 11 is formed inside the fitting hole 43.

  The case fastening screw 45 is disposed at a position where it does not contact the vibrator holder 25.

  The other components are the same as those in the first to fifth embodiments described above, and a description thereof will be omitted.

  The operation of the ultrasonic motor 10e in the sixth embodiment is the same as that of the first to fifth embodiments described above. However, the ultrasonic motor cases in the first to fifth embodiments are all integrated. Therefore, due to processing problems, it was necessary to form a nut insertion hole larger than the insertion hole of the vibrator holder.

  On the other hand, in the sixth embodiment, the case is divided into two in the vertical direction with the fitting hole of the vibrator holder as a boundary. Therefore, the fitting hole 41 for inserting the case has the outer dimensions of the laminated piezoelectric element 11 and the rotor. Processing can be performed with a size slightly larger than the diameter of the portion 26a. As a result, there is a margin in the thickness of the case, so that the outer diameter of the case can be made smaller than that of the cases of the first to fifth embodiments, and as a result, the motor itself can be downsized. .

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described with reference to FIGS.

  FIG. 32 is an exploded perspective view showing the configuration of the ultrasonic motor according to the seventh embodiment of the present invention. FIG. 33 is an assembly diagram of an ultrasonic motor according to the seventh embodiment, and FIG. 34 is a cross-sectional view of the ultrasonic motor according to the seventh embodiment.

  As shown in FIGS. 32 to 34, the ultrasonic motor 10f according to the seventh embodiment has a configuration between the nut 27 and the rotor portion 26a, compared to the configuration of the first embodiment described above. The ring 46 and the spring 47 are interposed. That is, from the rotor part 26a side, the ring 46 and the spring 47 are inserted into the shaft part 26b of the shaft-integrated rotor 26, and the nut 27 is further inserted into the shaft part 26b.

  The other components are the same as those in the first to sixth embodiments described above, and a description thereof will be omitted.

  Thus, according to the seventh embodiment, the operation of the ultrasonic motor 10f is the same as that of the first to sixth embodiments described above. However, for example, the configuration of the first embodiment described above cannot finely adjust the pressing force because the nut 27 directly presses the rotor portion 26a. On the other hand, in the seventh embodiment, since the spring 47 and the ring 46 are interposed between the nut 27 and the rotor portion 26a, the nut 27 is pushed by being pushed into the case 30. The force is transmitted such that the spring 47 receives the pressure, the restoring force of the spring 47 is received by the ring 46, and finally the ring 46 applies the force to the rotor portion 26a.

  Since the pressing force is determined by the amount of spring contraction × the spring constant of the constituent spring, it can be freely adjusted simply by changing the amount by which the nut 27 is pressed. Therefore, it is easy to adjust the pressing force.

  In the seventh embodiment, the spring 47 and the ring 46 are interposed between the nut 27 and the rotor portion 26a. However, the ring is not always necessary, and the rotor portion 26a is directly connected. The pressing force of the spring 47 may be received.

(Modification of the seventh embodiment)
In the above-described seventh embodiment, the pressing force of the nut is given by the spring 47 and the ring 46 interposed between the nut 27 and the rotor portion 26a, but the present invention is not limited to this.

  As a modification of the seventh embodiment, a case is configured to be detachable, and a leaf spring portion is provided on a lid portion that is one of the cases so as to apply a pressing force.

  FIG. 35 is an exploded perspective view of an ultrasonic motor according to a modification of the seventh embodiment of the present invention, and FIG. 36 is an external perspective view showing the configuration of the lid portion of the case of FIG. FIG. 37 is an assembly diagram of an ultrasonic motor according to a modification of the seventh embodiment, and FIG. 38 is a cross-sectional view of the ultrasonic motor according to a modification of the seventh embodiment.

  In the modification of the seventh embodiment, the case 50 includes a case base 51 and a lid 53. And the nail | claw 53a is provided in the part which contacts the nut 27 in the outer peripheral surface of the cover part 53 in multiple places, and four places in this case. A hook portion 53b is formed at the tip of the claw 53a. The hook portion 53b is for fixing the lid portion 53 corresponding to a hook portion 51b described later formed on the case base 51, and is formed to protrude inward from the claw 53a.

  Further, the upper surface of the lid portion 53 is formed such that the inner peripheral portion is recessed compared to the outer peripheral portion, and an opening 54 is formed at the center thereof at a position coinciding with the central axis O of the ultrasonic motor 10g. . In addition, slits are formed at a plurality of positions, in this case, at four positions, outward from the opening 54. A portion partitioned by the slit and recessed is configured as a leaf spring portion 53c having elasticity for contacting the upper surface of the nut 27 and pressing the nut 27.

  On the other hand, above the outer peripheral surface of the case base portion 51, a plurality of guide portions 51a for fitting with the claws 53a of the lid portion 53 described above are provided in four places in this case. These guide portions 51 a are formed so as to be slightly recessed as compared with other portions of the outer peripheral surface of the case base 51. Furthermore, a hook portion 51 b for fixing the lid portion 53 is formed by fitting the hook portion 53 b of the lid portion 53 at the end of these hook portions 51 a.

  That is, the claw 53 a and the hook portion 53 b of the lid portion 53 are positioned along the guide portion 51 a of the case base portion 51, and the hook portion 53 b of the lid portion 53 is engaged with the hook portion 51 b of the case base portion 51. Is attached to the case base 51. At this time, since the leaf spring portion 53c is deformed in contact with the upper surface of the nut 27, a restoring force of the spring is generated, so that an appropriate pressing force can be applied when the nut 27 is attached to the case 50. .

  According to such a modification, it is not necessary to bond the nut in a pressed state. In addition, even when an internal component such as a laminated piezoelectric element breaks down, the motor can be easily disassembled because it can be removed from the case by spreading the four claws hooked on the case.

(Eighth embodiment)
Next, an eighth embodiment of the present invention will be described with reference to FIGS.

  FIG. 39 is an exploded perspective view showing the configuration of the ultrasonic motor according to the eighth embodiment of the present invention. FIG. 40 is an assembly diagram of the ultrasonic motor according to the eighth embodiment, and FIG. 41 is a cross-sectional view of the ultrasonic motor according to the eighth embodiment.

  As shown in FIGS. 39 to 41, the ultrasonic motor 10h according to the eighth embodiment is configured such that the nut is formed on the upper portion of the ultrasonic motor according to the first to seventh embodiments described above. On the other hand, it is configured at the lower part of the motor.

  That is, not the shaft hole for penetrating the shaft portion 26 b of the shaft-integrated rotor 26 but the fitting hole 59 for fixing the vibrator holder 25 and the laminated piezoelectric element 11 are inserted into the central portion of the nut 58. Therefore, a hole 60 slightly larger than the outer dimension of the laminated piezoelectric element 11 is formed.

  On the other hand, the case 55 has no fitting hole for the vibrator holder 25 and is instead formed with a shaft hole 56 through which the shaft portion 26b of the shaft-integrated rotor 26 is inserted. Further, the fitting hole 57 for fitting the nut is opened from the lower side of the case 55 to the position of the upper surface of the rotor portion 26a. In this state, the nut 58 is bonded and fixed to the case 55.

  The other components are the same as those in the first to sixth embodiments described above, and a description thereof will be omitted.

  As for the assembly, the laminated piezoelectric element 11 is fitted into the fitting hole 59 of the nut 58 via the vibrator holder 25 and fixed, and the integrated nut 58 is fitted into the case 55 so that the shaft portion 26b can rotate. The nut 58 is fixed in a state of being pushed in the axial direction (rotor portion 26a side) so that an appropriate pressing force is obtained.

  For example, in the configuration of the first embodiment described above, the pressing is performed in the order of nut → rotor portion → laminated piezoelectric element, but the configuration of the eighth embodiment is called nut (laminated piezoelectric element) → rotor portion. Pressing in order.

  As described above, according to the eighth embodiment, an elliptical vibration combining the longitudinal and torsional vibration modes can be formed with only a single vibrator, and by rotating the rotor by the elliptical vibration, the axial direction can be obtained. Rotational force can be transmitted.

  In the eighth embodiment, the nut is described as being bonded and fixed to the case. However, the present invention is not limited to this. For example, similarly to the second embodiment described above, the nut and the fitting portion in the case may be fixed by forming a screw thread and screwing.

  Further, although the U-shaped vibrator holder is used, it is sufficient that the laminated piezoelectric element can be held by at least two pins as described above.

  Although the embodiment of the present invention has been described above, the present invention can be variously modified without departing from the gist of the present invention other than the above-described embodiment.

  Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.

  According to the present invention, an ultrasonic motor that is composed of a single member, has a simple structure, does not require a groove, and can be driven at a low voltage and can transmit rotational force in the axial direction. Is obtained.

10 ... ultrasonic motor 11 laminated piezoelectric element (vibrator), 12a, 12b ... frictional contact _{member, 13,13a 1, 13a 2, 13b} 1, 13b 2, 13c 1, 13c 2, 13d 1, 13d 2 ... external Electrode, 15a ... piezoelectric sheet 1 (piezoelectric sheet (1)), 15b ... piezoelectric sheet 2 (piezoelectric sheet (2)), 15c ... piezoelectric sheet 3 (piezoelectric sheet (3)), 16a ... internal electrode pattern 1 (internal electrode) Pattern (1)), 16b... Internal electrode pattern 2 (Internal electrode pattern (2)), 17a ₁ , 17a ₂ , 17b ₁ , 17b ₂ ... Upper cross finger electrode and central cross finger electrode, 18a ₁ , 18a ₂ , 18b ₁ , 18b ₂ ... lower interdigitated electrodes, 23 ₁ ... near the central node position of the torsional tertiary vibration and the node position of the longitudinal primary vibration, 23 ₂ ... the upper node position, 23 ₃ ... the lower part of the torsional tertiary vibration Node position, 25 25a, 25b ... transducer holder, 26 ... shaft integrated rotor, 26a ... rotor portion, 26b ... shaft, 27 ... nut, 28 ... shaft hole, 30 ... case, 31 ... fitting hole.

Claims (48)

A vibrator composed of a single piezoelectric element having a rectangular length ratio in cross section perpendicular to the central axis;
A vibrator holding member fixed to a portion corresponding to a common node of the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the vibrator;
A rotating part that is driven to rotate about a central axis that is in contact with the elliptical vibration generating surface of the vibrator and that is orthogonal to the elliptical vibration generating surface of the vibrator, and a rotated part that transmits the rotational force of the rotating part in the axial direction And a rotational force transmission member integrated with,
A friction contact member fixed to the elliptical vibration generating surface of the vibrator, and transmitting a rotational force generated by the elliptical vibration by frictional contact with the rotational force transmitting member;
A pressing member that forms a support hole for supporting the rotated portion of the rotational force transmitting member and presses the rotational force transmitting member toward the elliptical vibration generating surface of the vibrator while supporting the rotated portion of the rotational force transmitting member; ,
A first hole for accommodating the vibrator, a second hole for housing the vibrator holding member, and a third hole for housing the pressing member are formed, and the vibrator holding member is interposed therebetween. A holding member for holding the vibrator;
Comprising
By synthesizing a longitudinal primary resonance vibration expanding and contracting in the rotation axis direction of the vibrator and a torsional tertiary resonance vibration having the rotation axis as a torsion axis, an elliptical vibration is formed to rotate the rotational force transmitting member. Features an ultrasonic motor.   The ultrasonic motor according to claim 1, wherein a joint surface between the outer shape of the pressing member and the third hole of the holding member has a fitting shape.   The ultrasonic motor according to claim 1, wherein a joint surface between the outer shape of the pressing member and the third hole of the holding member has a screw shape.   The ultrasonic motor according to claim 1, wherein the vibrator holding member is formed in a U shape.   The ultrasonic motor according to claim 1, wherein the vibrator holding member is formed of at least two pin-shaped members.   The ultrasonic motor according to claim 1, further comprising a pressing fixing member that presses and fixes the pressing member to the holding member.   The ultrasonic motor according to claim 1, further comprising a rotary contact member between the pressing member and the rotational force transmitting member.   The ultrasonic motor according to claim 7, wherein the rotary contact member is rotated by frictional contact.   The ultrasonic motor according to claim 7, wherein the rotary contact member is rotated by rolling contact.   The ultrasonic motor according to claim 1, further comprising a rotary contact member between a rotated portion of the rotational force transmitting member and a support hole of the pressing member.   The ultrasonic motor according to claim 10, wherein the rotary contact member is rotated by rolling contact.   The ultrasonic motor according to claim 1, further comprising an elastic member between the pressing member and the rotational force transmitting member.   The holding member includes a first holding portion, a second holding portion, the first holding portion, and a second holding portion that are divided on the same plane as the surface of the hole that houses the vibrator holding member. The ultrasonic motor according to claim 1, further comprising: a screw member for fastening the holding portion. A vibrator composed of a single piezoelectric element having a rectangular length ratio in cross section perpendicular to the central axis;
A vibrator holding member fixed to a portion corresponding to a common node of the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the vibrator;
A rotating part that is driven to rotate about a central axis that is in contact with the elliptical vibration generating surface of the vibrator and that is orthogonal to the elliptical vibration generating surface of the vibrator, and a rotated part that transmits the rotational force of the rotating part in the axial direction And a rotational force transmission member integrated with,
A friction contact member fixed to the elliptical vibration generating surface of the vibrator, and transmitting a rotational force generated by the elliptical vibration by frictional contact with the rotational force transmitting member;
A hole for housing the vibrator and a hole for housing the vibrator holding member are formed, and the rotating portion of the rotational force transmitting member is placed in a state where the vibrator is held via the vibrator holding member. A pressing member that presses against the elliptical vibration generating surface of the vibrator;
A first hole for supporting the rotated portion of the rotational force transmitting member and a second hole for accommodating the pressing member are formed, and the supported portion of the rotating force transmitting member and the pressing member are held. A holding member;
Comprising
By synthesizing a longitudinal primary resonance vibration expanding and contracting in the rotation axis direction of the vibrator and a torsional tertiary resonance vibration having the rotation axis as a torsion axis, an elliptical vibration is formed to rotate the rotational force transmitting member. Features an ultrasonic motor.   The ultrasonic motor according to claim 14, wherein a joint surface between the outer shape of the pressing member and the second hole of the holding member has a fitting shape.   The ultrasonic motor according to claim 14, wherein a joint surface between the outer shape of the pressing member and the second hole of the holding portion has a screw shape.   The ultrasonic motor according to claim 14, wherein the vibrator holding member is formed in a U shape.   The ultrasonic motor according to claim 14, wherein the vibrator holding member is formed of at least two pin-shaped members.   The ultrasonic motor according to claim 14, further comprising a pressing fixing member that presses and fixes the pressing member to the holding member.   The ultrasonic motor according to claim 14, further comprising a rotational contact member between the rotational force transmitting member and the holding member.   The ultrasonic motor according to claim 20, wherein the rotary contact member is rotated by frictional contact.   The ultrasonic motor according to claim 20, wherein the rotary contact member is rotated by rolling contact.   The ultrasonic motor according to claim 14, further comprising a rotary contact member between a rotated portion of the rotational force transmitting member and the first hole of the holding member.   The ultrasonic motor according to claim 23, wherein the rotary contact member is rotated by rolling contact.   The ultrasonic motor according to claim 14, further comprising an elastic member between the holding member and the rotational force transmission member. A vibrator composed of a single piezoelectric element having a rectangular length ratio in cross section perpendicular to the central axis;
A vibrator holding member fixed to a portion corresponding to a common node of the longitudinal primary resonance vibration and the torsional tertiary resonance vibration of the vibrator;
A rotational force transmitting member that is driven to rotate about a central axis that is in contact with the elliptical vibration generating surface of the vibrator and is orthogonal to the elliptical vibration generating surface of the vibrator;
A friction contact member fixed to the elliptical vibration generating surface of the vibrator, and transmitting a rotational force generated by the elliptical vibration by frictional contact with the rotational force transmitting member;
A pressing member that presses the rotational force transmitting member toward the elliptical vibration generating surface of the vibrator;
A holding member for holding the pressing member;
Comprising
By synthesizing a longitudinal primary resonance vibration expanding and contracting in the rotation axis direction of the vibrator and a torsional tertiary resonance vibration having the rotation axis as a torsion axis, an elliptical vibration is formed to rotate the rotational force transmitting member. Features an ultrasonic motor.   The rotational force transmission member includes a rotating unit that is in contact with the elliptical vibration generating surface of the vibrator and is driven to rotate about a central axis that is orthogonal to the elliptical vibration generating surface of the vibrator, and a rotational force of the rotating unit as an axis 27. The ultrasonic motor according to claim 26, wherein the ultrasonic motor is integrally formed with a rotated portion that transmits in a direction.   The ultrasonic motor according to claim 27, wherein an outer shape of the pressing member and a surface of the holding member that contacts the pressing member have a fitting shape.   28. The ultrasonic motor according to claim 27, wherein an outer shape of the pressing member and a surface of the holding member that contacts the pressing member are screw-shaped.   28. The ultrasonic motor according to claim 27, wherein the vibrator holding member is formed in a U-shape.   28. The ultrasonic motor according to claim 27, wherein the vibrator holding member is formed of at least two pin-shaped members.   28. The ultrasonic motor according to claim 27, further comprising a pressing fixing member that presses and fixes the pressing member to the holding member. The pressing member forms a support hole for supporting the rotated portion of the rotational force transmitting member, and supports the rotational portion of the rotational force transmitting member on the elliptical vibration generating surface side of the vibrator. Press and
The holding member forms a first hole for housing the vibrator, a second hole for housing the vibrator holding member, and a third hole for housing the pressing member. Holding the vibrator through the member for
The ultrasonic motor according to claim 27.   The ultrasonic motor according to claim 33, further comprising a rotary contact member between the pressing member and the rotational force transmitting member.   The ultrasonic motor according to claim 33, wherein the rotary contact member is rotated by frictional contact.   The ultrasonic motor according to claim 33, wherein the rotary contact member is rotated by rolling contact.   34. The ultrasonic motor according to claim 33, further comprising a rotary contact member between a rotated portion of the rotational force transmitting member and a support hole of the pressing member.   The ultrasonic motor according to claim 37, wherein the rotary contact member is rotated by rolling contact.   The ultrasonic motor according to claim 33, further comprising an elastic member between the pressing member and the rotational force transmitting member.   The holding member includes a first holding portion, a second holding portion, the first holding portion, and a second holding portion that are divided on the same plane as the surface of the hole that houses the vibrator holding member. The ultrasonic motor according to claim 33, further comprising a screw member for fastening the holding portion. The rotational force transmission member includes a rotating unit that is in contact with the elliptical vibration generating surface of the vibrator and is driven to rotate about a central axis that is orthogonal to the elliptical vibration generating surface of the vibrator, and a rotational force of the rotating unit as an axis. A rotating part that transmits in the direction, and is integrally molded,
27. The ultrasonic motor according to claim 26, wherein the holding member supports the rotated portion of the rotational force transmitting member and holds the pressing member. The pressing member forms a hole for housing the vibrator and a hole for housing the vibrator holding member, and the rotational force transmitting member in a state where the vibrator is held via the vibrator holding member. Is pressed against the elliptical vibration generating surface of the vibrator,
The holding member forms a first hole for supporting the rotated portion of the rotational force transmitting member and a second hole for storing the pressing member, and supports the rotated portion of the rotational force transmitting member and the The ultrasonic motor according to claim 41, wherein the pressing member is held.   43. The ultrasonic motor according to claim 42, further comprising a rotational contact member between the rotational force transmitting member and the holding member.   44. The ultrasonic motor according to claim 43, wherein the rotary contact member is rotated by frictional contact.   44. The ultrasonic motor according to claim 43, wherein the rotary contact member is rotated by rolling contact.   43. The ultrasonic motor according to claim 42, further comprising a rotary contact member between a rotated portion of the rotational force transmitting member and the first hole of the holding member.   The ultrasonic motor according to claim 46, wherein the rotary contact member is rotated by rolling contact.   The ultrasonic motor according to claim 42, further comprising an elastic member between the holding member and the rotational force transmission member.

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