JPH04150781A - Ultrasonic vibrator - Google Patents

Abstract

PURPOSE:To get a vibrator of such structure that the tightening torque is needless and that it maintains symmetry about axis by caulking the shaft members arranged between opposed metallic blocks by temporary fastening method, and fixing these metallic blocks, by means of a fixing means. CONSTITUTION:A block member 1 and a block member 4 are fixed, holding a piezoelectric element 3 and an electrode plate 2, by the caulking of a large diameter part 7-a. A spring washer member 5 is provided for giving proper pressure contact force to the piezoelectric plate 0.5mm thick and for preventing the pressure contact force from changing by vibration. On the other hand, four sheets of electrode plates 2 are made of bronze, for example, 0.4mm thick, and out of them, the third electrode plate from the bottom in the figure is in contact, on the inside, with the shaft member 7 for junction, and it is electrically grounded together with the lowermost electrode plate in the figure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a vibrator used as an ultrasonic generation source in an ultrasonic motor, an ultrasonic cleaner, or the like.

(Prior Art) Conventionally, as this type of vibrator, for example, a bolted Langevin vibrator (hereinafter abbreviated as BLT) shown in FIG. 8 has been proposed.

In the BLT shown in FIG. 8, two piezoelectric element plates 3 are arranged between a metal block member 1 and a metal presser block member 4, and are screwed onto the central axis of these block members 1.4. The block member 1.4 is integrally fixed with the stud bolt 12 so as to sandwich the piezoelectric element plates 3 therebetween. Note that an electrode plate 2 is inserted between the block member 1 and the piezoelectric element 3.

For piezoelectric elements that are weak against tensile stress, the stud bolt 12 described above is used.
A compressive force bias is applied by tightening the piezoelectric elements 3 to prevent large tensile stress from being applied when an alternating current electric field is applied to each piezoelectric element 3 to cause it to expand and contract in the thickness direction.

(Problem M to be solved by the invention) By the way, in a vibrator with such a structure, when tightening the bolts, a strong tightening torque is required, so a two-sided chamfer with a tool such as a wrench attached to the metal block side is used. Parts 1-C and 4-C are provided to prevent rotation for tightening to maintain time.

The rotation stopper, such as the two-chamfered portion 1-C14-C, is not only unnecessary for the vibration function of the motor, but may also excite unnecessary vibration modes.

Furthermore, in an ultrasonic motor using such a vibrator that has been proposed in recent years, an exploded view of which is shown in FIG. -a
, 3-B-a, there is one in which the polarization direction is reversed within one piezoelectric element. This can be done by applying a voltage as shown in FIG. 5 to the piezoelectric element (hereinafter referred to as the A-phase piezoelectric element) and the piezoelectric element whose boundary line is perpendicular (hereinafter referred to as the B-phase piezoelectric element). It gives vibrations as shown in FIG. 7, which is rope-jumping vibration centered around the axis of the vibrator 9, and is an ultrasonic motor configured to rotate a rotor 8 that is in pressure contact with the vibrator. . Incidentally, FIG. 6 shows an example in which four piezoelectric elements are used to achieve low voltage input.

By the way, in the ultrasonic motor, the A-phase piezoelectric element and the B-phase piezoelectric element are connected to the boundary lines 3-A-a and 3-B-a, respectively.
If they are not perpendicular to each other, the above-mentioned rope-jumping vibration will cause an elliptical motion instead of a perfect circle in a plane perpendicular to the axis, resulting in a motor with low efficiency. However, in the type of BLT where the piezoelectric element, metal block, and electrode plate are tightened and fixed with bolts, the strong tightening causes rotational torque between the piezoelectric elements, causing the boundary between them. This will cause a shift in the perpendicular positional relationship of the lines.

In addition, if there is a non-axisymmetric part such as the rotation stopper,
The vibrations caused by the A-phase piezoelectric element and the B-phase piezoelectric element do not degenerate (the resonant frequencies of the A phase and B phase match), which also results in a motor with low efficiency.

An object of the present invention is to provide a vibrator which does not require torque for tightening which causes the above-mentioned problem, and which maintains axial symmetry.

[Means to solve the problem]

In order to achieve the object of the present invention, an electro-mechanical energy conversion element is inserted between opposing metal block members, these metal blocks are integrally fixed by a fixing means, and the electro-mechanical energy conversion element is In the ultrasonic vibrator sandwiching the metal blocks, the fixing means is characterized in that the metal blocks are fixed by crimping a shaft member provided between the opposing metal blocks using a crimping method.

(Function) The ultrasonic transducer having the above configuration is sandwiched between the metal block members because no rotational force is applied to the metal block members in the direction around their axis when fixing the metal block members. For example, no misalignment occurs between two electro-mechanical energy conversion elements such as piezoelectric elements.

〔Example〕

FIG. 1 is a sectional view of Example 1 of an ultrasonic motor in which the vibrator of the present invention can be effectively implemented. The motor of this example has a total length of 28 mm+ including the mounting flange member, and a diameter of the vibrator of 10 mm. The four piezoelectric elements have the configuration shown in FIG. 6, and by applying the voltage shown in FIG. 5 to the piezoelectric elements, the entire vibrator performs a rope-jumping motion as shown in FIG. 7.

A friction sliding portion 1-e having a 45° taper is formed on the end face of the vibrator, and any one point of the friction sliding portion is approximately perpendicular to the tapered surface. When viewed from the axial direction of the vibrator, it is circular motion, and KN-5
A rotary motion is applied to the hard alumite-treated rotor 8 which is in contact with the IC-plated friction sliding part. 13 is a gear member made of polyacetal resin, and the rotational force of the rotor 8 is transmitted to the gear member via a friction clutch portion 8-a. The maximum friction torque generated by the friction clutch section is set to be smaller than the friction torque generated by the friction sliding section when the vibration is stationary, so that the starting torque when the rotor rotates due to the skipping motion of the vibrator is determined by the maximum frictional rotational force of the friction clutch portion. vice versa,
The structure is such that when a rotational force is applied from the gear member 13 side when the vibration is stationary, the friction clutch portion slips. The bearing member 14 is a mating gear (not shown) of the gear member 13.
It simultaneously receives a force in the radial direction generated by the engagement with the friction sliding part 1"e, and a reaction force in the thrust direction corresponding to the compressive force of the spring member 15 provided to apply an appropriate pressure contact force to the frictional sliding part 1"e. The separation contact member 16 is made of polyacetal resin, and is arranged to fit on the inner diameter of the bearing member, and receives the reaction force of the spring member, and at the same time, is fitted on the inner diameter side of the brass metal block 1 with a clearance of about 20 μ-. are combined.

The role of the separation contact member 16 is to approximately determine the axis of the rotor, and in this embodiment, it does not rotate itself. In other words,
The friction sliding portion 1-e has a tapered conical shape, but if it is in contact with only this narrow tapered portion, the rotor axis will undergo a precession motion (a motion whose locus is the generatrix shape of the cone). ), and the rotor does not rotate stably. Therefore, the separation contact portion 1 of the separation contact inner member 16
In this embodiment, 6-a contacts the inner diameter side of the metal block to provide a restoring force in response to the fall of the rotor, thereby preventing the rotor axis from falling significantly relative to the axis of the vibrator. As a result, the grinding motion mentioned above is also suppressed as much as possible. Reference numeral 17 denotes a mounting flange for mounting the vibrator to a fixing member (not shown), which is fastened to a shaft threaded portion 7-b formed at the tip of the joining shaft member 7. The joining member 7 is inserted so as to pass through the block member 1.4, etc., as shown in the figure, and has a small diameter shaft portion 7-c formed in the axial center thereof, and a shaft threaded portion two b. The large diameter shaft portion 7-a on the opposite end side has a flanged portion 7-d that comes into contact with the stepped portion 1-g formed on the inner diameter shaft portion of the block member 1.
is formed.

The small-diameter shaft portion 7-c insulates the vibration of the vibrator, and is mounted so that almost no vibration is transmitted to the flange member 1f.

A recess 4 of the block member 4 is provided at the tip of the large diameter shaft portion 7-a.
-d, a joining collar member 6 and a spring washer member 5 are attached. The tip of this large-diameter shaft portion 7-a is formed in the shape shown by the broken line in the figure, and a crimping jig (not shown) is applied to the V-shaped groove 7-h provided on the end surface. By tightening the V-shaped groove 7-h so as to expand it, the tip portion is crushed and the projection 7-i is extended.

Therefore, the block member 1 and the block member 4 are connected to each other by crimping the large diameter shaft portion 7-a, so that the piezoelectric element 3 and the electrode plate 2
is clamped and fixed.

In this embodiment, the spring washer member 5 is used to apply an appropriate pressure contact force to the piezoelectric element having a thickness of 0.5H;
This is provided to prevent the pressure contact force from changing due to vibration.

On the other hand, these four electrode plates 2 have a thickness of, for example, 0.4
The third electrode plate from the bottom in the figure is in contact with the joining shaft member 7 on the inner diameter side, and is electrically connected to the bottom electrode plate in the figure. It is in a grounded state.

The concave circumferential groove 1-f formed on the outer peripheral surface of the block member 1 has the effect of lowering the resonance frequency of the primary bending vibration mode of the vibrator and increasing the displacement of the friction sliding part. There is.

That is, according to this embodiment, when the piezoelectric element 3 and the electrode plate 2 are clamped and fixed by the block member 1 and the block member 4, the joining shaft member is fixed by crimping, so that these piezoelectric elements and the electrode plate It is fixed without coming off.

The other members of the vibrator of this example configured in this way are exactly the same, and instead of the connecting shaft member, bushing member, and spring washer, bolts are used, and threads are cut on the inner diameter of the metal block member 1. The performance was compared by driving a conventional type vibrator in which a piezoelectric element was clamped and fixed. In this case, the conventional type vibrator has a resonant frequency fr of approximately 3
It was 4KHz. At this time, the fr difference between A phase and B phase, that is, △f'', was a maximum of 130 Hz.As a result, the maximum efficiency was 40% and the maximum starting torque was 60 gf-c+a under the rotor pressurizing force of 350 gf and 60 Vp-p driving conditions. Ta.

On the other hand, in the ultrasonic motor using the vibrator of this example, the Δfr of the vibrator was reduced to a maximum of 50 Hz, the maximum efficiency was 60%, and the starting torque gradually improved to 80 gf-cm under the same driving conditions.

FIG. 2 is a sectional view of Example 2 of the vibrator according to the present invention. 2 is an electrode plate, and 4 is a holding metal block. The shaft portion 1-a is integral with the metal block 1, and has a slit 1-d at its tip.After passing the joining collar 6 through the shaft portion, the slit is pushed out and caulked. There is. At this time, a spring washer 5 is inserted to prevent excessive pressure from being applied to the piezoelectric element 3. In other words, because of the spring washer 5, even if the bottom dead center position is slightly shifted in the axial direction when the collar 6 is pushed down, an appropriate pressing force determined by the spring strength of the spring washer 5 is applied to the piezoelectric element 3. It turns out.

The dimensions of the vibrator are 130 mm in total length and 50 m in diameter.
m, and the material purchased is carbon steel. As a result, the resonant frequency was approximately 20 K) Iz. Also, if the pressure force applied to the piezoelectric element 3 is too small, the Q value of the vibrator (=
This is a numerical value indicating internal loss, and the smaller the value, the greater the loss), and the smaller the atomic sense, so it is necessary to select an appropriate spring strength for the spring washer 6. or,
It is easy to use spring washers that have the characteristic that the generated force does not change much even if the applied displacement changes slightly.

FIG. 3 is a sectional view of Example 3. This type has a structure similar to riveting in which the tip 7-a of the caulking shaft 7 is crushed (upset) and the piezoelectric element 3, electrode plate 2, presser metal block 4, and metal block 1 are fixed by pressure. It has become. Since the holding metal block 4 is provided with a notch 4-b, the collar portion 4-a acts as a spring and applies an appropriate pressure contact force to the piezoelectric element 3. Note that the processing method called upset is a processing method commonly used in shrimp molding.

FIG. 9 shows an example of a configuration in which an ultrasonic motor using a vibrator shown in FIG. 'M1 is used to drive the barrel of an optical lens. A gear 22 is coaxially connected to the rotor 8 and transmits rotational output to the gear 23, thereby rotating a lens barrel 24 having a gear that meshes with the gear 23. In order to detect the rotational position and rotational speed of the rotor 8 and the lens barrel 24, an optical encoder slit plate 25 is arranged coaxially with the gear 23, and a photocoupler 26 detects the positional speed.

(Effects of the Invention) As explained above, according to the present invention, there is no need for a rotation stopper such as a double chamfer to attach a jig to a metal block member, so the processing cost is low, and bending vibrations are synthesized to achieve the above-mentioned effect. As a vibrator that utilizes vibrations that cause rope-jumping vibrations, an excellent vibrator can be obtained because it maintains symmetry with respect to the axis.

Furthermore, the same effect as described above can be obtained by not using a bolt having a non-axially symmetrical lead portion.

Furthermore, since rotational torque such as bolt tightening is not applied to the piezoelectric element or the vibrator that requires positioning to the electrode plate, there is no fear of misalignment. Moreover, the shaft crimping of the present invention requires only a short time to process, and has the effect of greatly simplifying the process.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a first embodiment of an ultrasonic motor using a vibrator of the present invention, Fig. 2 is a sectional view showing a second embodiment of the present invention, and Fig. 3 is a sectional view showing a third embodiment of the present invention. 4 is an exploded perspective view of a conventional ultrasonic motor, FIG. 5 is a waveform diagram of the AC power applied to the piezoelectric element of the vibrator that vibrates the rope, and FIG. 6 is a diagram of another conventional ultrasonic motor. Exploded perspective view of Figure 7 (
a) and (b) are a front view and a plan view illustrating the rope jumping vibration, 's8 figures (a) and (b) are a plan view and a front cross-sectional view of a bolted Langevin vibrator, and Fig. 9 is a vibration of the present invention. 1 is a schematic diagram showing an output device of an ultrasonic motor using a motor. 1... Metal block member 1-a... Shaft 1-b...
・Shaft tip part 1-c...Double chamfer part 1-d...
Slit 1-e...Frictional sliding portion 1-f...Constriction 2...Electrode plate member 3...Piezoelectric element member 4...Metal block member for holding 4-a...Brim portion 4 -b...notch 4-
c... Double-chamfered portion 5... Spring washer member 6... Joining collar member 7... Joining shaft member 7-
a... Shaft tip 7-b... Shaft threaded part 7-c.
...Small diameter shaft portion 8...Rotor member 8-a...Friction clutch portion 9...Vibrator 10...Insulating member
11... Bolt member 12... Studded bolt member 1
3-... Gear member 14... Bearing member 15-...
・Spring member 16... Separation contact member 16-a...
Separate contact portion 17... Installation is done by flange and 4 other people.

Claims (1)

[Claims] 1. An electro-mechanical energy conversion element is inserted between opposing metal block members, these metal blocks are integrally fixed by a fixing means, and the ultrasonic wave is generated by sandwiching the electro-mechanical energy conversion element. An ultrasonic transducer characterized in that the fixing means fixes the metal blocks by crimping a shaft member provided between the opposing metal blocks using a crimping method. 2. The ultrasonic transducer according to claim 1, wherein the shaft member constituting the fixing means passes through opposing metal block members. 3. The ultrasonic transducer according to claim 1, wherein the shaft member constituting the fixing means extends from either one of the opposing metal block members. 4. An ultrasonic motor comprising the ultrasonic vibrator according to claim 1 and a moving member rotationally driven by vibrations excited by the vibrator. 5. An apparatus including an ultrasonic motor according to claim 4, further comprising an output member for extracting an output from a moving member of the ultrasonic motor.