DD143682A1 - PIEZOELECTRIC VIBRATION DRIVE - Google Patents

Abstract

The drive realizes both rotary and

Description

Title of the invention Piezoelectric vibration drive

Field of application of the invention

The invention relates to a piezoelectric vibration drive for the realization of rotational or translational movements, which can be used for direct stepwise drive or * by the juxtaposition of small steps continuously moving elements such as imaging plates, magnetic cards, credit cards, tapes, etc. in the medium data technology.

Characteristic of the known technical solution

Drive devices for o.g. Applications are known to be realized by motors or stepper motors via corresponding mechanical transmission elements, with a relatively high mechanical complexity associated with large dimensions is necessary * These devices also have the disadvantage that the required position accuracies · are not easily achieved.

Furthermore, it is known, a piezoelectric Längsschwiüger, which is provided at both ends with electromagnets, by suitable control of the piezoelectric column

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and the magnet non-positively along a V-shaped or otherwise shaped slideway of magnetic material to move (DL-PS 99264). A disadvantage is that the lying in the micrometer range amplitudes of the piezoelectric column, which can reach frequencies> 10 kHz, can be transmitted with the magnet only at frequencies below 1 kHz. To eliminate these disadvantages, it is known to form the clamping elements as piezo elements, which engage in a clamping rail with a square or circular cross-section (DL-PS 110992). The disadvantage here is that the possible clamping distance is a few micrometers, whereby a high machining accuracy required and the reliability is not guaranteed even at low wear. It is also known to realize the clamping operation by tilting generated by piezoelectric columns or by ball locks (US Pat. No. 3,292,019). Disadvantages are functional uncertainties and occurring accuracy problems.

Aim of the invention;

The object of the invention is to transfer the relatively small and fast movements of piezoelectric elements to an output element without high accuracy requirements in order to produce small steps for realizing high positional accuracies of the continuous movements composed of small carriages.

Explanation of the essence of the invention

- The technical problem, which is solved by the invention, is to connect a vibrator via a drive element with an output member so that by spring action, a connection is formed, wherein the Pederandruckkraft is varied in synchronism with the vibration.

Features of the invention;

Features of the invention are that the structure of the vibrator is such that by delayed activation of the e.g. on a continuous steel plate symmetrically mounted piezoelectric bending elements or the two acting on a rocker arm piezoelectric columns of the contact pressure, with which the friction lining is pressed at the end of the transmission lever elastically to an output element, synchronously amplified or attenuated to vibration. In a particularly advantageous embodiment of the invention, a combination of piezosäule and mass element is perpendicular to the direction of vibration mounted to increase the contact pressure, wherein in phase-in control due to the inertial forces occurring an additional contact pressure or a reduction thereof takes place. In a further embodiment of the invention, the vibrator is designed as a cylinder made of piezoceramic with electrodes on the inner and outer sheath, wherein the change of the inner volume is transmitted to a plunger upon application of a voltage with a liquid via a diaphragm or a piston and so a large / eg translation allows.

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embodiment

The invention will be explained in more detail below with reference to two exemplary embodiments

 The accompanying drawings show:

Fig. 1: Overall view of a piezo-vibration drive with two bending elements on a common steel plate.

Pig. 2: Overall view of a piezo-vibration drive with two Yibrationselementen of piezo columns, which act on a common rocker arm.

Pig. 3: Overall view of a piezovibration drive with additional piezo column and ground for generating the contact pressure.

Pig. 4: Overall view of a piezovibration drive with a forceps-shaped transmission element for driving flat bodies.

Pig. 5: arrangement of several drives to realize uniform movements.

Pig. 6: piezovibrator from a tube oscillator.

The piezoelectric vibratory drive according to the invention shown in Pig * 1 consists of the stripper made of thin thin spring rod 2, on which 2 pairs of piezoelectric elements 1 are glued, which are metallized on the glued and opposite surface. "The two belonging to a pair of strips are electrically connected in parallel and effect depending on. Polarization of the applied stress a bending of the steel

lamella 2. With the same control, the steel plate is symmetrically deformed symmetrically and the transmission lug 3 executes a linear reciprocating movement. When the two bending elements are driven with a defined phase shift, e.g. a resistor or an inductance are connected in series, it is achieved that the transmission lever 3, e.g. is more strongly pressed in the forward movement of the output member 5 and lifts off in the backward movement of this. By switching this process can also run backwards. This achieves a rotational movement of the output element 5 either in the forward or reverse direction.

Hach Fig. 2, the same process can be achieved by the phase-shifted control of the two piezoelectric columns 7, and according to the technical principle of the stroke smaller and the forces are greater. The piezoelectric columns 7 act on the common rocker arm 8 pressed by pedals 9 and on the transmission lever 3 rigidly connected thereto.

In your example shown in Pig, 3, the stroke generated in the piezoelectric column 12 formed as a vibrator transmitted to the disc 5 via the transmission lever 3 by a perpendicular to the direction of movement arranged further piezo column 14 phaseηsynchroη is driven by their expansion, the mass 15 moves and with the resulting inertial force the friction lining 4 presses stronger against the disc 5. The pressure spring 17 ensures that manufacturing accuracies and possibly occurring wear are compensated for · In the forward and backward movement of the vibrator is added by phase-responsive control of the piezoelectric column H in one direction, the inertial force to the spring force and in the other direction of the spring force

a ι / α »ι

subtracted. When inventively correct dimensioning the spring force is released in a direction of movement, whereby, a return without contact with the disc 5 is possible.

The exemplary embodiment illustrated in FIG. 4 uses a flat disk made of metal or directly a data carrier as the drive body 22. The vibration vibrations of the vibrator 18 are coupled by two piezoelectric elements 21 arranged on both sides of a pincer-shaped drive part 19 and perpendicular to the direction of movement, and mass elements 20 attached thereto.

When phasenricb.tiger control takes place in a direction of movement due to the inertial forces a clamping and in the other direction of movement, an opening of the pliers. Thickness differences and wear are compensated by the spring properties of the pliers halves.

In Fig. 5 is an overview of an embodiment of a piezoelectric vibration drive with multiple drive elements shown. In antiphase control of the two drive units and taking into account the slip that always occurs between the arrival »drive elements 23 and the disc 24, one can achieve an approximately uniform movement of the disc 24.

In Fig. Β, the embodiment of a piezoelectric vibrator according to the invention is shown. The tubular body 28 made of piezoceramic is metallized on the outer and inner lateral surfaces 29. The two ends of the tube are closed by specially shaped end plates, which are designed so that they deform elastically with a reduction in the diameter of the pipe ends * This is a more elastic

Completion of Rohreadeα reached.

When changing the internal volume bulges the fluid .23, with which the cylinder is filled, the elastic membrane 30 with the bore in the end plate 26 is closed. A plunger 31 is moved over the membrane. According to the invention, the relatively large volume change in the cylinder, depending on the diameter of the bore on the membrane 30, causes a relatively large distance of a few centimeters to a few millimeters.

Claims (11)

claim 1. Piezoelectric vibration drive for rotational and translational movements for the direct stepwise or by the juxtaposition of small steps continuously moving drive 'of data carriers in magnetomotive data storage, characterized, characterized that the vibrator (1, 7, 12, 23, 29) of piezoelectric bending elements (1) or of a piezoelectric column (7, 12) or a piezoelectric ring oscillator (28) is realized, wherein by phase-shifted control of the bending elements (1) or the piezo columns (7) presses the transfer lever (3) with the friction lining (4) against the disc (5) to be driven, carrying the data carrier and executes one or more movement steps. 2. Piezoelectric vibration drive according to item 1, characterized that the pressure of the transmission lever (3) with friction lining (4) to the driven pulley (5) by means of another vibrator, the piezoelectric column (14), with its main axis arranged perpendicular to the direction of movement of the Ubertragungshebels (3), and synchronously with the piezoelectric column (12) is driven by applying a voltage. 3. Piezoelectric vibration drive according to pt. 1 and 2, characterized, that synchronous to the direction of the over-. Pressing (3) contact pressure by a peder-mass system (14, 15, 17) is realized, wherein the piezoelectric column (14) is connected to a Masseel-ement (15) and accelerates upon application of a voltage, the mass element (15) and realized an additional pressure generated by the spring (17). " ~ 3- 111 IM 4. Piezoelectric vibration drive according to item 1, characterized that consisting of two active elements vibrator consists of a continuous steel plate (2) which is attached to the holders (6) on the frame, that symetrically glued on this lamella each two in the same direction polarized piezoelectric bending elements (1) electrically so are controlled delayed, that based on the operating frequency, a phase shift of the voltage of approximately j \ / 4 arises that the friction lining (4) comes, and on the transmission lever (3) in a force-locking operative connection with the driven disc (5) of the transmission Bebel (3 ) generates a torque on the driven pulley (5). 5. Piezoelectric vibration drive after. Point 4 »characterized that a change in the direction of movement of the driven pulley (5) by switching the phase shift of the voltage applied to the piezoelectric bending elements (1) voltage is achieved. 6. Piezoelectric vibration drive according to item 1 to 5, characterized that a plurality of drive elements (23) are arranged around the driven pulley (5), which generate an approximately continuous movement by alternately acting on the pulley (5), 7. Piezoelectric vibration drive after. Points 1 and 6, characterized that the piezosäulen (7) are electrically delayed so controlled that based on the operating frequency, a phase shift of the voltage of about Λ. / 4 is created and a kraftSchlussige operative connection between transmission lever (3) and to be driven pulley (5) is produced, --ί- »J 1 1 / L 8. Piezoelectric vibration drive according to item 1, 2 and 3, characterized, in that the stroke generated by the piezoelectric column (12) is transmitted to the disk (5) by means of a transmission lever (3) and a spring-mass system (14 * 15, 17) arranged perpendicular thereto. 9. Piezoelectric vibration drive according to item 1, 2, 4, 5 and 7, characterized, in that the transmission lever (19) attached to the piezo column (12) is tongs-shaped, the transmission lever (19) is a flat output element, e.g. an information carrier (22) surrounds, that on the pliers of the transmission lever (19) mutually effective Piezosäuleη (21) are arranged, which are connected to ground elements (20) and upon application of a voltage to the piezoelectric columns (21) closing the elastic pliers on Cause transmission lever (19) and that in synchronous control of the piezoelectric columns (12, 21), a stepwise movement of the information carrier (22). 10. Piezoelectric vibration drive according to item 1 to 9, characterized, in that a plurality of drive elements (23) are arranged around the driving disc (5) and act alternately on the disc (5) to be driven, 11. Piezoelectric vibration drive according to item 1 to 10, characterized, that the vibrator consists of a cylindrical piezoelectric -Ή- \ 17- electric ring oscillator (28) whose outer and inner lateral surface (29) are metallized, which is filled with an incompressible liquid (27) and at the ends with two end plates (26) is closed in such a way that the end plates (26) by elastic deformation follow the changes in diameter of the ring oscillator (28), wherein in one of the end plates (26) has a bore (32) is closed by a diaphragm (30) or a piston, by, the change in shape of the cylindrical ring oscillator (28) and the end plates (26) upon application of a voltage to the metallized lateral surfaces (29) is moved according to the change in the internal volume of the ring oscillator (28) and acts on the plunger (31). Dazu_3_Sei! En drawings