Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF TH~ INVENTION
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The present invention relates to an ultrasonic driving device
having a structure for decreasing wear between a stator and a
rotary member.
In a known ultrasonic motor using a ring type piezoelectric
vibrator, two groups of electrodes are attached to one end of a
ring type piezoelectric ceramic, the two groups of electrodes are
so positioned that standing waves respectively genera-ted by the
two groups of electrodes are shif-ted every ~/2 in each position.
The parts of the ring type piezoelectric vibrator corresponding to
the electrode are alternately polarized in reverse. Also, the
two groups of the electrodes are respectively connected to two
oscillators for respectively generating alternating current vol-
~ages having ~/2 phase shift from each other. When the alternat-
ing current voltages from the lwo oscillators are respectively
applied to the two groups of electrodes, the two standing waves
having ~/2 phase shift from each other are generated on the sur-
faces of the ring type piezoelectric vibrator and then progressive
waves owing to an compound of -the two standing waves generate on
the surfaces of the ring type piezoelectric vibrator. Therefore,
when a slider attaching a rotary member is put on the ring type
piezoelectric vibrator and is s-trongly pressed to the ring type
piezoelectric vibrator, the rotary member is rotated by the pro-
gressive waves.
In the prior ultrasonic motor, however, the slider is easily
worn out because the slider of the rotary member is directly pres-
sed on the piezoelectric vibrator.
There is known an ul-trasonic motor comprising a Langevin type
vibrator having two ring type piezoelectric vibrators which are
put between two metal blocks. In this ultrasonic motor, a twist-
ing joint body is connected to the end of the one metal block by a
bol-t for fixing the metal blocks and the piezoelectric vibrator
and a rotary member is pressed on the twisting joint body by a
spring.
In this ultrasonic motor, however, the rotary member is easi-
ly worn out because the rotary member is pressed on the twisting
joint body.
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SUMMARY _F THE INVENTIO_
It is, therefore, -the primary object of the present inven-tion
to provide an ultrasonic driving device having a structure for
decreasing wear of a rotary member or a stator.
It is another object of -the present invention to provide an
ultrasonic driving device having a rotary membèr in which balls,
disks or rolls are rotatably attached for decreasing wear of the
rotary member.
It is another object of the present invention to provide an
ultrasonic driving device in which lubricate oil is supplied to
the circumference of balls, disks or rolls of a rotary member for
decreasing wear of the rotary member.
In order to accomplish the above and other object, the pre-
sent invention comprises a sta-tor for generating a progressive
wave by driving a piezoelectric vibrator or vibrators, a rotary
member rotatably attaching a plurality balls, disks or rolls, and
pressure means for making the balls, disks or rolls contac-t with
the stator.
BRIEF DESCRIPT-[_N OF THE DRAWINGS
Fig. 1 shows a sectional v:iew of an ultrasonic motor in the
prior art.
Fig. 2 shows a plane view of a form of a piezoelectric vibra-
~or and a composition of electrodes of the piezoelectric vibrator
in the ultrasonic motor in Fig. 1.
Fig. 3 shows a separated perspective view of the stator of an
ultrasonic motor in the prior art.
Fig. 4 shows a side view having a partial sectional view of
an ultrasonic motor in the prior art.
Fig. 5 shows a side view of an ultrasonic driving device pro-
vided by the present applicant.
Fig. 6 shows a side view of one part of an ultrasonic driving
device of an embodiment in the presen-t invention.
Fig. 7 shows a plane view of a rotary member of the ultra-
sonic driving device in Fig. 6.
Fig. 8 shows a view for explaining a principle of an ultra-
sonic driving device in Fig. 6.
Fig. 9 shows a side view of an ultrasonic driving device of
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rhe other embodiment according to -the present invention.
Fig. 10. shows a plane view of a rotary member of ultrasonic
driving device in Fig. 9.
Fig. 11 shows a plane view of an ultrasonic driving device of
another embodiment according to the present invention.
Fig. 12 shows a side sectional view of an ultrasonic driving
device another embodiment according to the present invention.
Fig. 13 shows a side sectional view of an ultrasonic driving
device another embodiment according to the present invention.
Fig. 1~ shows a side view of a concrete composition of the
ultrasonic driving device in Fig. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the prior art in Fig. 1, a ring type piezo-
electric vibrator B is attached -to a ring type resilient member A
a n d t h e p i e z o e l e c t r i c v i b r a t o r
B vibrates with the resilient member. The pieæoelectric vibrator
B is divided in 17 parts by the ration of e.g. 22.5 or 11.25.
The respective neighbouring portions in the 17 parts of the piezo-
electric vibrator B are polarized by a reverse polarity to each
other as shown in Fig. 2. The two portions C and D in the one
side of the piezoelectric vibrator B are respectively attached as
an electrode by conductive paint as shown in Fig. 2. The portion
G in Fig. 2 shows an earth electrode. The member F to be driven
to which slider E is attached is mounted on the resilient member
A.
In the ultrasonic motor in the pri.or art, the alternating
current voltage of Vosinwt is applied to the one electrode C and
the alternating current voltage Vocoswt is applied to the other
electrode D, where Vo is an instantaneous value, w is radian
frequency and t is time. The phases of these voltages shift by
rl/2 from each other. Thereby, the divided portions of the piezo-
electric vibrator B alternately produce expansion and contraction
and thus, the resilient member A produces bending vibration.
Therefore, a standing wave is generated in the resilien-t member A
and a progressive wave is generated on the resilient member A.
Thus, the driven member F having the slider E is rotated on the
resilient member A.
However, in the prior ultrasonic motor, because the slider E
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lS strongly contacted with the resilient member A, the slider E or
the resilient member ~ is worn out and the life of the ul-trasonic
motor is short.
Referring to the prior art in Fig. 3, a piezoelectric vibra-
tor 3, a terminal plate 4, a piezoelectric vibrator 5, a terminal
~la~_e 6 and an aluminum disk 7 aLe put on a washer 1 and a bolt 2
is inserted through the center holes of these members. The screw
~a of the bolt 2 is engaged with the screw hole 8a of a twisting
joint body 8. A drain 8b is formed on the under surface of the
twisting joint body 8, arcuate projections 8c are formed in both
sides of drain 8b, and a beam 8d is so formed in the upper portion
of the twisting joint body 8 that an angle between the beam 8d and
drain 8b becomes a predetermined value.
In this prior ultrasonic driving device, when alternating
current voltage is applied through the terminal plates 4 and 6 to
the piezoelectric vibrators 3 and 5 and the piezoelectric vibra-
tors 3 and 5 are vibrated in the direction of their thickness, the
arcuate projections 8c of the twisting joint body 8 are pushed and
twisted by the vibration of the piezoelectric vibrators 3 and 5.
Therefore, the twisting joint body 8 is vibrated to be twisted.
When the excitation fre~uency of the alternating current voltage
approaches a resonance fre~uency, elliptic vibration arises on the
beam 8d of the twisting joint body 8.
Therefore, as shown in Fig. 4, a rotary member 9 is put on of
the beam 8d of the twisting joint body 8, a center bolt 10 passed
through a bearing 11 of the rotary member 9 fixes the twisting
body 8, and a spring 12 is attached between the upper end of the
bolt 10 and the bearing 11, whereby the rotary member 9 is strong-
ly touched on the beam 8d of the twisting joint body 8 and is ro-
tated by the elliptic vibration on the beam 8d.
However, in the prior ultrasonic motor, because the rotary
member 9 is strongly contacted with the beam 8d of the twisting
joint body 8, the beam 8d or the rotary member 9 is worn out and
t-he life of the ultrasonic motor is short.
Referring to Fig. 5, in the ultrasonic driving device provid-
ed b~ the present applicant, ring type piezoelectric vibrators 13
of piezoelectric ceramics are put between a short metal block 1~
and a long metal block 15, male screw threads 16a and 16b at both
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ends of a bolt 16 are engaged with female screw threads of the
metal blocks 14 and 15, whereby a stator 17 is constituted. A
rotary member 18 is strongly contacted with one end of the stator
17 by a spring.
In the above ultrasonic driving device, when alternating cur-
~ent voltage is supplied to the piezoelectric vibrators 13, the
vibration toward the thickness arises in the piezoelectric vibra-
~ors 13 and then presses -the rnetal blocks 14 and 15. The pressure
of the metal blocks 14 and 15 is influenced by the screw threads
16a and 16b of the bolt 1~, whereby twist vibration arises in the
metal blocks 14 and 15. When the resonance frequency of the twist
vibration is coincident with that of the vibration toward the
thickness of the piezoelectric vibrators 13, a progressive wave
(ellipse vibration) arises on the ends and side portion of the
stator 17. Therefore, when the rotary member 18 is contacted with
the end of the stator 17, the rotary member 18 is smoothly rotat-
ed.
In the ultrasonic driving device, however, the rotary member
18 is strongly pressed to the stator 17 by a spring for transmit-
ting the ellipse vibration generated on the end of -the stator 17
~o the rotary member 1~. Therefore, the contact faces between the
end of the stator 17 and the rotary member 18 are worn on each
other. Thus, a lining material is put between the end of the sta-
tor 17 and the rotary member 18 for decreasing the wear between
the stator 17 and the rotary member 18. However, even if the lin-
ing material is put between the end of the stator 17 and rotary
rnember 18, the lining material is worn out, noise generates in the
contact face between the stator 17 and the rotary member 18 and
the life of the ultrasonic driving device is short.
Referring to Figs. 6 and 7, a plurality of balls 19 are ro-
tatably supported in the rotary member 20 and these balls are
contacted with the end of the stator 17 as shown in Fig. 5. One
end of a bolt 22 is engaged with screw -threads at the end of the
stator 17 and the other end of the bolt 22 is passed through the
center holes of the rotary member 20, a pressure member 21 and a
s p r i n g w a s h e r 2 3 a n d t h e n , a n u t 2 4 a r e
engaged with the screw threads at the other end of the bolt 22.
Therefore, the balls 19 are pressed on the end of the stator 17 by
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the pressure member 21.
Explaining the motion of -the ultrasonic driving device ac-
cording to the present invention, in fig. 8, when the progressive
wave is generated on the end of the stator 17 as shown by the ar-
rows B, the balls 19 are rotated in the direction of arrows A.
When the balls 19 are rotated in the direction of arrows A, fric-
tion arises on the contact por-tion between the balls 19 and the
surface 21a of the pressure member 21 and thus the balls 19 roll
on che surface 21a of the pressure rnember 21. The rotary member
20 is rotated toward the arrow C according to the rotation of the
balls 19.
Therefore, when teeth of a gear are formed on the side of the
rotary member 20 and are engaged with another gear, the rotary
force of the rotary member 20 is transmitted through the other
gear to the other machine and the ultrasonic driving device ac-
cording to the present invention is used instead of a known elec-
tric motor.
When lubricative oil is supplied to the circumference of the
balls 19, the lubricative oil influences the rotation of the balls
19 for good, because the balls are respectively contacted with the
surface 21a of the pressure member 21 by each point and are glided
on the end of the stator 17. The wear of the balls 19, the end of
the stator 17 and the pressure member 21 is decreased. Therefore,
the life of the ultrasonic driving device according to the present
invention becomes long.
Referring to Fig. 9, 17 designates a stator, 20; a rotary
member, 21; a pressure member, 22; a bolt, 23; a washer, 24; a
nut. These compositions are the same as those in Fig. 6 and a
plurality of disks or rolls are rotatably supported with the
rotary member 20 in a circle instead of the balls 19.
The ultrasonic driving device of this embodiment is driven
the same as the above embodiment and has the same effect.
Referring to Figs. 11 and 12, electrodes 26a and 26b are
formed on both ends of a ring type ceramic piezoelectric vibrator
26, and a member 27 for transmitting vibration and a member 28 for
not transmitting vibration are closely attached with the same
t-hickness on the electrode 26a of the piezoelectric vibrator 26.
A bolt 29 is passed through the holes of the close portion between
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che members 27 and 28, the piezoelectric vibrator 26 and the
electrodes 26a and 26b and holes of a rotary member 20 supporting
balls 19 and a pressure member 21. The screw threads at both ends
of the bolt are engaged with nuts 30a and 30b and these elements
are fixed.
The ultrasonic driving device having this ring type piezo-
electric vibrator 26 is provided by the applican-t. When al-ternat-
ing current voltage is app~ied ~o the electrodes 26a and 26b in
the ultrasonic driving device, a progressive wave is generated
from its circumferential edge to its center edge on both sides of
the piezoelectric vibrator 26. Therefore, the balls transmitted
through the member 27 and thus the rotary member 20 is rotated
with the balls 19.
In this embodiment, rolls and disks are used instead of the
balls as shown in Figs. 9 and 10.
Referring to Fig. 13, in an ultrasonic driving device of
another embodiment accordi.ng to the present invention, a resilient
member 27 and a pie~oelectric vibrator 26 are the sarne as the re-
silient member A and the piezoelectric vibrator B in Fig. 1. A
plurality of balls 19 supported ~ith a rotary member 27. A rotary
shaft 28 of the rotary member 20 protrudes beyond a bearing 30 of
a case 29. A screw 31 is engaged with the screw of the resilient
mernber 27 through the holes of a bottorn plate 29a and a washer
31a, and the bottom plate 29a is fixed with the case 29 by screws
29b. Therefore, the balls 19 are strongly contacted with the in-
side of the case 29 and the surface of the resilient member 27 by
the rotation of the screw 31.
In the ultrasonic driving device of another embodiment ac-
cording to the present invention, the balls 19 are rotated with
the progressive wave, whereby the rotary member 20 is rotated.
Therefore, the rotary force is obtained from the rotary shaft 28.
In this embodiment, rolls and disks are used instead of the
balls as shown in Figs. 9 and 10.
Referring to Fig. 14, in an ultrasonic driving device of
another embodiment according to the present invention, a stator
17 comprises a short metal block 14, a long metal block 15 ancl a
bolt 16 and is the same as the stator 17 in Fig. 5. A hole 32 is
ormed through the metal blocks 14 and 15 and bolt 16 and a bolt
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33 is passed through the hole 32. The one end of bolt 33 is en-
gaged with a nut 34b through a spring washer 34c and the other end
of the bolt 33 is passed through a bearing 20a supported with a
rotary member 20 and a hole of a pressure member and is engaged
with a nut 34a. Balls 19 rota-tably supported with the rotary mem-
ber 20 are pressed between the end of the stator 17 and the pres-
sure member 21. Both ends of an arm 37 having a rotary shaft 36
are fixed with both sides of the rotary member 20.
In this ultrasonic driving device, when the balls 19 are ro-
tated owing to the progressive wave generated on the end of the
stator 17, the rotary member 20 is rotated and the rotary shaft 36
is rotated. Therefore, this ultrasonic driving device can be used
instead of the known electric motor.
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