JPH1056786A - Drive unit employing electromechanical conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive unit employing small electromechanical conversion elements which can be assembled easily and the number of components is decreased. SOLUTION: A piezoelectric chamber 11a and a slider chamber 11b are formed on a base 11 and a piezoelectric element 12 has one end bonded to an end part 11e and the other end bonded to the end part of a drive shaft 13. A slider 14 is supported slidingly on the drive shaft 13 supported movably in the axial direction by a partition 11c and an end part 11d. Under a state where the drive shaft 13 penetrates the slider 14, a frictional member 15 is set in a notch 14a and applied with a coil spring 17 thus friction coupling the drive shaft 13, the slider 14 and the frictional member 15. The coil spring 17 is tightened while setting the length of circumferential contacting part with the slider 14 and the frictional member 15 shorter than the length of the coil spring in the winding direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device using an electromechanical transducer.

[0002]

2. Description of the Related Art Some driving devices using electromechanical transducers have already been proposed. The actuator shown in FIGS. 22 and 23 is an example, and is an impact type actuator using a piezoelectric element as an electromechanical transducer.
Hereinafter, the configuration and operation will be briefly described. FIG. 22 is an exploded perspective view showing the actuator, and FIG. 23 is a perspective view showing an assembled state of the actuator.

Referring to FIGS. 22 and 23, an actuator 100 includes a frame 101, support blocks 103 and 104 on the frame 101, a drive shaft 106, and a piezoelectric element 10.
5, the slider 102 and the like. Drive shaft 106
Are supported movably in the axial direction by a support block 103a and a support block 104. One end of the piezoelectric element 105 is adhesively fixed to the support block 103, and the other end is adhesively fixed to one end of the drive shaft 106. The drive shaft 106 is supported so as to be displaceable in the axial direction (the direction of the arrow a and the direction opposite thereto) when the piezoelectric element 105 is displaced in the thickness direction.

A drive shaft 106 is provided on a slider 102 in a lateral direction.
An opening 102a is formed in an upper portion through which the drive shaft 106 penetrates, and an upper half of the drive shaft 106 is exposed. A pad 108 which is in contact with the upper half of the drive shaft 106 is inserted into the opening 102a.
Is provided with a projection 108a at its upper part. The projection 108a of the pad 108 is pushed down by a leaf spring 109, and a downward urging force F is applied to the pad 108 so as to abut the drive shaft 106.

[0005] With the above configuration, the slider 102 including the pad 108 and the drive shaft 106 are pressed against each other by the urging force F of the leaf spring 109 and are frictionally coupled.

Next, the operation will be described. First, when a sawtooth wave drive pulse having a gentle rising portion and a rapid falling portion as shown in FIG. 24A is applied to the piezoelectric element 105, the piezoelectric element 105 is driven at the gentle rising portion of the driving pulse. The drive shaft 106 gently expands and displaces in the thickness direction, and the drive shaft 106 coupled to the piezoelectric element 105 also moves in the forward direction (the direction of arrow a).
Displaced slowly. At this time, the slider 102 frictionally coupled to the drive shaft 106 is driven by the frictional coupling force.
It moves in the forward direction with.

In the rapidly falling portion of the driving pulse, the piezoelectric element 105 is rapidly contracted and displaced in the thickness direction.
The drive shaft 106 connected to 05 also rapidly displaces in the negative direction (the direction opposite to the arrow a). At this time, the slider 102 frictionally coupled to the drive shaft 106 overcomes the frictional coupling force due to the inertial force and substantially stays at that position and does not move. By continuously applying the driving pulse to the piezoelectric element 105, the slider 102 can be continuously moved in the positive direction.

[0008] The term "substantially" used herein means that the slider 102 and the drive shaft 10 are movable in both the forward direction and the opposite direction.
The frictional coupling surface between the actuator 6 and the motor 6 moves while sliding, and moves as a whole in the direction of the arrow a due to the difference in driving time.

In order to move the slider 102 in the opposite direction (the direction opposite to the arrow a), the waveform of the sawtooth-wave driving pulse applied to the piezoelectric element 105 is changed, and the speed is changed as shown in FIG. This can be achieved by applying a drive pulse composed of a gentle rising portion and a gentle falling portion.

[0010]

A driving device using the above-described piezoelectric element moves the moving member depending on a frictional force between the driving member (driving shaft) and the moving member (slider). Therefore, the magnitude of the frictional force greatly affects the driving characteristics and reliability of the driving device. As described above, in the conventional driving device, the frictional force is applied to the contact surface between the driving member and the moving member by using the leaf spring. Also becomes smaller. However, when the dimension of the leaf spring is reduced, the length of the fulcrum and the point of action of the leaf spring is shortened, so that the spring becomes hard (the spring constant increases), and it becomes difficult to finely set the magnitude of the frictional force. There was a problem.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. According to the first aspect of the present invention, there is provided a base and an electromechanical transducer having one end fixed in the direction of expansion and contraction to the base. A driving member coupled to the other end of the electro-mechanical conversion element in the expansion and contraction direction and supported to be movable in the expansion and contraction direction of the electro-mechanical conversion element; and a frictionally coupled to the driving member, the expansion and contraction direction of the electro-mechanical conversion element. A driving member using an electromechanical conversion element comprising: a moving member movably supported by the moving member; and a frictional force applying means for applying a frictional force between the driving member and the moving member. The means is constituted by a coil spring, and applies a frictional force to the contact surface between the driving member and the moving member by the elastic force in the direction of tightening.

The driving member has a columnar shape, and the moving member includes a plurality of members obtained by dividing a cylindrical member into a plurality of members along an axial direction. Preferably, a frictional force is applied to a contact surface between the driving member and the moving member by winding the moving member including the plurality of members against the driving member.

In the frictional force applying means constituted by the coil spring, the length in contact with the moving member may be shorter than the length of one turn of the coil spring in the circumferential direction.

Further, the moving member comprising the plurality of members and the frictional force applying means comprising a coil spring are disposed substantially coaxially with the cylindrical driving member.

It is preferable that the moving member has a protrusion extending along the axial direction, and the coil spring abuts the protrusion to wind up the driving member.

According to the present invention, the base and one end of the base in the direction of expansion and contraction are fixed to the base, and a drive voltage is applied so that expansion and contraction are performed at different speeds during expansion and contraction. A mechanical conversion element, a driving member coupled to the other end of the electromechanical conversion element in the expansion / contraction direction, and supported movably in the expansion / contraction direction of the electromechanical conversion element; and a frictionally coupled to the driving member; In a driving device using an electromechanical conversion element constituted by a moving member movably supported in a direction in which the element expands and contracts, the moving member is constituted by a coil spring, and the driving member is formed by a resilient force in a tightening direction. It is characterized by friction coupling.

Preferably, the driving member has a columnar shape, and the moving member constituted by the coil spring is disposed substantially coaxially with the columnar driving member.

Further, in the invention according to any one of claims 1 and 6, the moving member constituted by the coil spring may be a coil spring wound a plurality of times.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
Are formed with a piezoelectric element chamber 11a and a slider chamber 11b. A bearing hole for supporting the drive shaft 13 is formed at the center of the end 11d of the base 11 and the partition 11c between the piezoelectric element chamber 11a and the slider chamber 11b, and the drive shaft 13 moves in the axial direction. Freely supported. The piezoelectric element 12 is housed in the piezoelectric element chamber 11a, one end of which is adhesively fixed to the wall surface of the end 11e, and the other end of which is adhesively fixed to the end of the drive shaft 13. The drive shaft 13 is supported movably in the axial direction by a partition 11c and an end 11d of the base, and the slider 14 and the output unit 16 are supported movably in the axial direction on the drive shaft 13.

A notch 14a is formed in the slider 14 so that an upper half of the drive shaft 13 is exposed, and a friction member 15 that contacts the upper half of the drive shaft 13 is disposed in the notch 14a. You. When the drive shaft 13 penetrates into the slider 14, the friction member 15 is disposed in the notch 14a, and the coil spring 17 is fitted outside the notch 14a, so that the drive shaft 13, the slider 14 and the friction member 15 are frictionally connected. Let it. The output unit 16 is a member that transmits motion to a driven member. The coil spring 17 sets the length of the contact portion between the slider 14 and the friction member 15 and the circumferential direction of the coil spring to be shorter than the length of the coil spring in the winding direction, so that the slider 14 and the friction member 15 are tightened. Good to do.

When a sawtooth drive pulse having a gentle rising portion and a rapid falling portion is applied to the piezoelectric element 12,
In the gentle rising portion of the drive pulse, the piezoelectric element 12 is gently extended in the thickness direction and displaced, and the drive shaft 13 coupled thereto is also gently displaced in the forward direction (the direction of arrow a). At this time, since the slider 14 frictionally coupled to the drive shaft 13 moves in the forward direction together with the drive shaft 13 due to the frictional coupling force, the output section 16 fixed to the slider 14 also moves in the forward direction.

In the rapid falling portion of the drive pulse, the piezoelectric element 12 is rapidly contracted and displaced in the thickness direction, and the drive shaft 13 connected thereto is also rapidly displaced in the negative direction (the direction opposite to the arrow a). The slider 14 and the output portion 16 frictionally coupled to the drive shaft 13 overcome the frictional coupling force due to the inertial force and substantially stay at that position and do not move. By continuously applying the driving pulse to the piezoelectric element 2, the slider 14
And the output unit 16 can be continuously moved in the positive direction.

[0023]

Embodiments of the present invention will be described below. FIG. 1 is an exploded perspective view showing the structure of the driving device according to the first embodiment.
FIG. 2 is a perspective view showing the assembled state. In FIGS. 1 and 2, the entire driving device using a piezoelectric element is indicated by reference numeral 10. 11 is a base, the whole is cylindrical,
A part of the piezoelectric element 12 is cut away leaving a side wall.
Are formed, a slider chamber 11b for accommodating a piezoelectric element chamber 11a for accommodating the same, an slider 14, and an output section 16 integrated therewith.

The end 11 d of the base 11 and the piezoelectric element chamber 11
A bearing hole for supporting the drive shaft 13 is formed in the center of the partition wall 11c between the a and the slider chamber 11b, and the drive shaft 13 is supported movably in the axial direction. The other end 11 e of the base 11 is used for fixing the driving device 10.

The piezoelectric element 12 is accommodated in the piezoelectric element chamber 11a, and one end of the piezoelectric element is bonded and fixed to the wall surface of the end 11e. At the other end of the piezoelectric element, the end of the drive shaft 13 is adhered and fixed, and when the piezoelectric element undergoes expansion and contraction displacement in the thickness direction,
The drive shaft 13 is configured to be displaced in the axial direction.

A slider 14 and an output section 16 are arranged in the slider chamber 11b, and a drive shaft 13 passes through the vicinity of the center of the slider 14 and the output section 16. The slider 14 and the output unit 16 are configured to be point-symmetric about the drive shaft 13 with respect to the central axis. The drive shaft 13 includes the base partition 11c and the end 1
1d, the slider 1 is supported movably in the axial direction.
The output unit 4 and the output unit 16 are supported on the drive shaft 13 so as to be movable in the axial direction. Since the side wall of the output section 16 contacts the side wall of the slider chamber 11b and is guided in the axial direction, the slider 14 and the output section 16 do not rotate around the drive shaft 13.

A notch 14a is formed in the slider 14 so that an upper half of the drive shaft 13 penetrating therethrough is exposed. A friction member abutting on the upper half of the drive shaft 13 is provided in the notch 14a. 15 is arranged. Slider 1
In a state where the drive shaft 13 penetrates into the inside of the housing 4, the friction member 15 is arranged in the notch 14 a, and the coil spring 17 is fitted to the outside thereof. Thereby, the drive shaft 13, the slider 14 and the friction member 15 can be brought into pressure contact with each other by the elasticity of the coil spring 17 and can be frictionally coupled. The output portion 16 is a member that transmits motion to the driven member. For example, an appropriate member is fixed to a screw hole 16a provided outside the output portion 16 and coupled to the driven member, for example. To communicate.

The coil spring 17 sets the length of the contact portion between the slider 14 and the friction member 15 and the circumferential direction of the coil spring shorter than the length of the coil spring in the winding direction.
4 and the friction member 15 are rolled up.

Next, the operation will be described. First, when a saw-tooth wave driving pulse having a gentle rising portion and a rapid falling portion as shown in FIG. 24A is applied to the piezoelectric element 12, the piezoelectric element 12 is driven at the gentle rising portion of the driving pulse. The piezoelectric element 12 is gradually extended in the thickness direction and displaced.
The drive shaft 13 that is coupled to is also gently displaced in the forward direction (the direction of the arrow a). At this time, since the slider 14 frictionally coupled to the drive shaft 13 moves in the forward direction together with the drive shaft 13 due to the frictional coupling force, the output section 16 fixed to the slider 14 also moves in the forward direction.

In the rapidly falling portion of the drive pulse, the piezoelectric element 12 is rapidly contracted and displaced in the thickness direction.
Is rapidly displaced in the negative direction (the direction opposite to the arrow a). At this time, the slider 14 and the output portion 16 frictionally coupled to the drive shaft 13 overcome the frictional coupling force due to the inertial force and substantially stay at that position and do not move. By continuously applying the drive pulse to the piezoelectric element 2, the slider 14 and the output unit 16 can be continuously moved in the positive direction.

The term “substantially” as used herein means that the frictional coupling surface between the slider 14 and the drive shaft 13 slides in both the forward direction and the opposite direction while causing slippage, and is caused by a difference in drive time. That which moves in the direction of arrow a as a whole is also included.

In order to move the slider 14 in the opposite direction (the direction opposite to the arrow a), the waveform of the saw-tooth wave driving pulse applied to the piezoelectric element 12 is changed, and the speed is changed as shown in FIG. This can be achieved by applying a drive pulse composed of a gentle rising portion and a gentle falling portion.

Next, a second embodiment will be described. FIG. 3 shows the second
FIG. 2 is a perspective view illustrating a configuration of the driving device 20 according to the embodiment, which is disassembled.
FIG. 4 is a perspective view showing the assembled state. The second embodiment is different from the first embodiment in the configuration of the slider and the friction member, and the configuration of the other portions is not different from the first embodiment. Therefore, only the different portions will be described and are the same as the first embodiment. Portions are given the same reference numerals and description thereof is omitted.

A slider 24 and a spring fixing member 25 connected to the slider 24 are arranged in the slider chamber 11b, and the drive shaft 13 passes through the vicinity of the center of the slider and the spring fixing member. The slider 24 and the spring fixing member 25 are
The point is symmetrical with respect to the central axis. Slider 2
An annular protrusion 24a is provided on one side surface of the fourth member 4 at a portion where the drive shaft 13 penetrates, and the spring fixing member 25 is fitted to the annular protrusion 24a with a coil spring 26 described later being built in. Since the coil spring 26 is sandwiched between the annular projection 24a and the spring fixing member 25 without loosening, the coil spring 26 does not tilt with respect to the drive shaft 13 (when it tilts, the frictional force changes). 26 moves the slider 24
Is transmitted to Screw holes 2 provided on the outside of the slider 24
An appropriate member is fixed to 4a, and is configured to transmit motion to the driven member by being coupled to the driven member or the like.

The coil spring 26 is formed in a partially open annular shape having an inner diameter smaller than the outer diameter of the drive shaft 13 and is frictionally coupled to the drive shaft 13 by its elastic force. Thereby, the movement of the drive shaft 13 is controlled by the slider 24 via the coil spring 26.
Is transmitted to

Next, the operation will be described. First, when a saw-tooth wave driving pulse having a gentle rising portion and a rapid falling portion as shown in FIG. 24A is applied to the piezoelectric element 12, the piezoelectric element 12 is driven at the gentle rising portion of the driving pulse. The piezoelectric element 12 is gradually extended in the thickness direction and displaced.
The drive shaft 13 that is coupled to is also gently displaced in the forward direction (the direction of the arrow a). At this time, the coil spring 26 frictionally coupled to the drive shaft 13 moves in the forward direction together with the drive shaft 13 due to the friction coupling force.
4 also moves in the forward direction.

In the rapidly falling portion of the drive pulse, the piezoelectric element 12 is rapidly contracted and displaced in the thickness direction.
Is rapidly displaced in the negative direction (the direction opposite to the arrow a). At this time, the coil spring 26 frictionally coupled to the drive shaft 13 and the slider 24 and the spring fixing member 25 incorporating the coil spring 26 overcome the frictional coupling force due to the inertial force and substantially stay at that position and do not move. By continuously applying the drive pulse to the piezoelectric element 12, the slider 24 can be continuously moved in the positive direction. The term “substantially” as used herein means that the frictional coupling surface between the coil spring 26 and the drive shaft 13 slides in both the forward direction and the opposite direction while causing slippage, and the entirety is driven by the difference in drive time. Moving in the direction of arrow a.

A third embodiment will be described. FIG. 5 shows the third
FIG. 2 is a perspective view illustrating a configuration of an exploded drive device 30 according to the embodiment. In FIG. 5, reference numeral 31 denotes a base, which is a column here, but may be a block of any shape without being limited to the column. 32
Is a piezoelectric element. One end of the piezoelectric element 32 is adhesively fixed to an end face of the base 31, and a cylindrical driving member 33 is adhesively fixed to the other end of the piezoelectric element 32. A groove 33a is formed circumferentially on the outer peripheral surface of the driving member 33, and an annular coil spring 36, which is partially open, is fitted into the groove 33a. Coil spring 3
Since the coil spring 6 is inserted into the groove 33a, there is no possibility that the coil spring is inclined with respect to the drive shaft (the inclination changes the frictional force). The shape and dimensions of the groove 33 a are set to be equal in width and depth to the diameter of the wire forming the coil spring 36, and the surface of the inserted coil spring 36 is configured to substantially match the outer peripheral surface of the driving member 33.

Reference numeral 34 denotes a slider, which has a hole 34a extending in the axial direction at the center thereof, and a cylindrical driving member 33 is inserted into the hole 34a. Groove 33a of drive member 33
The coil spring 36 is urged in the direction in which the diameter of the coil increases, so that when the driving member 33 is inserted into the slider 34, the coil spring 36 is fixed to the inner surface of the hole 34 a of the slider 34. The coil spring 36
And the slider 34 are frictionally coupled.

Next, the operation will be described. As in the case of the first and second embodiments, when a sawtooth drive pulse is applied to the piezoelectric element 32 having a gentle rising portion and a rapid falling portion as shown in FIG. At the gentle rising portion of the pulse, the piezoelectric element 32 is gently extended in the thickness direction and displaced, and the driving member 33 coupled to the piezoelectric element 32 is also gently displaced in the forward direction (the direction of arrow a). At this time, the slider 34 frictionally connected to the coil spring 36 inserted into the driving member 33 is moved by the frictional coupling force.
It moves in the forward direction with.

In the rapid falling portion of the drive pulse, the piezoelectric element 32 is rapidly contracted and displaced in the thickness direction.
The driving member 33 and the coil spring 36 fitted in the driving member 33 are also rapidly displaced in the negative direction (the direction opposite to the arrow a). At this time, the slider 34 frictionally coupled to the coil spring 36 overcomes the frictional coupling force due to its inertia force and substantially stays at that position and does not move. Piezoelectric element 32
, The slider 34 can be continuously moved in the positive direction.
The term “substantially” as used herein means that the friction coupling surface between the coil spring 36 and the slider 34 slides in both the forward direction and the opposite direction while causing slippage, and as a whole, due to the difference in drive time. One that moves in the direction of arrow a is also included.

A fourth embodiment will be described. FIG. 6 shows the fourth
FIG. 2 is a perspective view illustrating a configuration of an exploded drive device 40 according to the embodiment. In FIG. 6, 41 is a base, 43 is a driving member,
4 is a slider, 45 is a spring fixing member, and 46 is a coil spring. A driving member 43, a spring fixing member 45, and a coil spring 46 are fitted on the slider 44, and the slider 44 is provided on the base 41. It slidably penetrates the hole 41a.

Reference numeral 42 denotes a piezoelectric element. One end of the piezoelectric element 42 is adhesively fixed to an end face of the base 41 away from the hole 41a, and one side of a driving member 43 is adhesively fixed to the other end of the piezoelectric element 42. You. On the other side surface of the driving member 43, an annular projection 43a is provided at a portion through which the slider 44 penetrates, and the spring fixing member 45 is fitted into the annular projection 43a with the coil spring 46 incorporated therein. The coil spring 46 is connected to the driving member 4.
The movement of the driving member 43 is transmitted to the coil spring 46 because the driving member 43 is sandwiched between the spring fixing member 45 and the spring fixing member 45 without looseness. The coil spring 46 is formed in a partially open annular shape having an inner diameter smaller than the outer diameter of the slider 44, and is frictionally coupled to the slider 44 by its elastic force.

Next, the operation will be described. As in the first to third embodiments, when a sawtooth drive pulse is applied to the piezoelectric element 32 having a gentle rising portion and a rapid falling portion as shown in FIG. At the gently rising portion of the pulse, the piezoelectric element 42 gently expands and displaces in the thickness direction, and the driving member 43 coupled to the piezoelectric element 42 also gently displaces in the positive direction (the direction of arrow a). At this time, since the coil spring 46 sandwiched between the driving member 43 and the spring fixing member 45 without looseness is frictionally coupled to the slider 44, the slider 44 is moved in the forward direction together with the driving member 43 by the friction coupling force. Moving.

In the rapid falling portion of the driving pulse, the piezoelectric element 42 is rapidly contracted and displaced in the thickness direction, and the driving member 4
3. The fixing member 45 and the coil spring 46 are also moved in the negative direction (arrow a).
In the opposite direction). At this time, the slider 44 frictionally coupled to the coil spring 46 overcomes the frictional coupling force due to its inertia force and substantially stays at that position and does not move. By continuously applying the drive pulse to the piezoelectric element 42, the slider 44 can be continuously moved in the positive direction. The term “substantially” as used herein means that the frictional coupling surface between the coil spring 46 and the slider 44 slides in both the forward direction and the opposite direction while causing slippage, and as a whole, due to the difference in driving time. One that moves in the direction of arrow a is also included.

The third embodiment shown in FIG. 5 and FIG.
In the fourth embodiment, the slider 34 (44) is described to move with respect to the fixed base 31 (41). However, the slider 34 (44) is fixed and the base 31 (41) is fixed.
It is also possible to use such as moving.

FIGS. 7 and 8 show a first modification of the structure of the frictional coupling portion between the drive shaft 13, the slider 14, and the friction member 15 in the first embodiment. The drive shaft 13 shown in FIG. As is clear from the cross-sectional shape perpendicular to the axial direction of the slider 14, the side surfaces 14s, 15
s is deleted, the coil spring 17 is prevented from contacting at the deleted portion, and the contact length between the slider 14 and the friction member 15 is shorter than the length of the coil spring 17 in the winding direction. The coil spring 17 uses a plurality of annular coil springs, each of which is partially open.

Referring to FIG. 8, an example of the frictional force generated in the frictional connection will be described. The coiling elastic force of the coil spring 17 acts as pressing forces P1 and P2 on the corners 15a and 15b of the removed portion of the side surface of the friction member 15, so that the contact surface between the drive shaft 13 and the friction member 15 and the slider 14 Drag N1 is generated. Drive shaft 13, friction member 15, and slider 14
Is expressed as the product of the drag force N1 and the friction coefficient μ of the contact surface.

FIGS. 9 and 10 show a second modification of the structure of the friction coupling portion between the drive shaft 13, the slider 14 and the friction member 15 in the first embodiment, which is similar to the structure shown in FIG. Although the configuration is such that the coil spring 17 is wound a plurality of times without any interval, it is used. The frictional force generated at the frictional coupling portion will be described with reference to FIG. The coiling elastic force of the coil spring 17 acts as pressing forces P3 and P4 on the corners 15a and 15b of the removed portion 15s on the side surface of the friction member 15, and as a result, the force between the drive shaft 13 and the friction member 15 and the slider 14 Drag N2 is generated at the contact surface.

FIGS. 11 and 12 show a third modification of the configuration of the frictional coupling portion between the drive shaft 13, the slider 14 and the friction member 15 in the first embodiment. The drive shaft 13 shown in FIG. As is clear from the cross-sectional shape perpendicular to the axial direction, the slider 14 and the friction member 15 are provided with protrusions 14p and 15p extending along the axial direction. Since the coil spring 17 is wound outside the projections 14p and 15p, the coiling elastic force of the coil spring 17 is
Act as pressing forces P5 and P6 on the corners 15a and 15b of the projection 15p. As a result, a drag N3 is generated on the contact surface between the drive shaft 13 and the friction member 15 and the slider 14, and a friction force is generated between the drive shaft 13 and the friction member 15 and the slider 14.

FIGS. 13 and 14 show a fourth modification of the structure of the frictional coupling portion between the drive shaft 13, the slider 14 and the friction member 15 in the first embodiment. The drive shaft 13 shown in FIG. As is clear from the cross-sectional shape perpendicular to the axial direction, when the slider 14 and the friction member 15 are arranged so as to surround the drive shaft 13, the whole extends along the axial direction.
It is formed to have a square cross section. The ridges 14r and 15r located at the center of each of the slider 14 and the friction member 15 are configured to be higher in height in the radial direction than the other ridges. Since the coil spring 17 is wound outside the ridge 14r and the ridge 15r, the coiling elastic force of the coil spring 17 acts on the ridge 15r of the friction member 15 as a pressing force P7. As a result, a drag N4 is generated on the contact surface between the drive shaft 13 and the friction member 15 and the slider 14, and a friction force is generated between the drive shaft 13 and the friction member 15 and the slider 14.

FIGS. 15 and 16 show a fifth modification of the configuration of the frictional coupling portion between the drive shaft 13 and the slider 14 and the friction member 15 in the first embodiment. The drive shaft 13 shown in FIG. As is clear from the cross-sectional shape perpendicular to the axial direction, the whole is a cylindrical shape extending along the axial direction, and is substantially divided into three along the axial direction. The occupying friction member is composed of two friction members 15a and 15b, and is configured to occupy approximately ／ of the upper side.

Since the coil spring 17 is wound outside the slider 14 and the friction members 15a and 15b, the elasticity of the coil spring 17 acts on the friction members 15a and 15b as pressing forces P8, P9, P10 and P11. . As a result, drags N5 and N6 are generated on the contact surfaces between the drive shaft 13 and the friction members 15a and 15b, and a friction force is generated between the drive shaft 13 and the friction members 15a and 15b and the slider 14.

FIGS. 17 and 18 show a sixth modification of the structure of the frictional coupling portion between the drive shaft 13 and the slider 14 and the friction member 15 in the first embodiment. The drive shaft 13 shown in FIG. As is clear from the cross-sectional shape perpendicular to the axial direction, the whole is a cylindrical shape extending along the axial direction, and is substantially divided into two along the axial direction.
/ 2, and the friction member 15 is configured to occupy approximately 1/2 of the upper side.

The coil spring 17 is wound around the slider 14 and the friction member 15, and the coil spring 17 is
And the friction member 15 contacts almost the entire peripheral surface, and the coil spring 17
The elastic force of the tightening is applied to the friction member 15 by pressing forces P12 and P1.
Acts as 3. As a result, the drive shaft 13 and the friction member 1
5, a drag N7 is generated on a contact surface between the drive shaft 13 and the friction member 15 and the slider 14, and a frictional force is generated between the drive shaft 13 and the friction member 15 and the slider 14.

However, in this configuration, the contact state between the coil spring and the slider 14 and the friction member 15 is not stable due to an error in incorporating the coil spring and a shape error of the slider 14 and the friction member 15. The direction of action of the pressing forces P12 and P13 shown in FIG. 18 indicates the direction of action of the pressing force in the least efficient contact state. That is,
Depending on the contact state between the coil spring and the slider 14 and the friction member 15, a remarkably large pressing force is required to generate a desired magnitude of frictional force, and when the contact state changes, a large frictional force is suddenly applied. For example, it is difficult to stably generate a desired frictional force.

In the drive device using the piezoelectric element described above, a coil spring is used to generate a frictional force on the contact surface of the drive shaft, the slider, and the frictional connection portion of the friction member. Experimental results on the relationship between the number of windings of the spring, the generated frictional force, and the variation in the frictional force will be described.

FIG. 19 is a graph showing the relationship between the number of turns of the coil spring and the generated frictional force (the average value of variation). The frictional force increases in proportion to the number of turns of the coil spring. It can be seen that the ratio of increase in the frictional force becomes lower when the ratio exceeds.

FIG. 20 is a graph showing the relationship between the number of turns of the coil spring and the variation in the generated frictional force (the difference between the maximum value and the minimum value). The variation in the frictional force increases in proportion to the number of turns of the coil spring. However, it can be seen that when the number of windings exceeds n2, the rate of increase in variation in frictional force increases. The number of turns n2
Is almost the same value as the number of turns n1 described above.

FIG. 21 is a graph showing the relationship between the number of turns of the coil spring and the variation in the frictional force due to the difference in the mounting direction of the end point of the coil spring. The vertical axis indicates the case where the position of the end point of the coil spring is variously changed. 3 shows the difference between the case where the frictional force is the largest and the case where the frictional force is the smallest. It can be seen that the variation in frictional force decreases as the number of windings of the coil spring increases, but when the number of windings exceeds n3, the variation in frictional force decreases and does not change much. The number of turns n3 is a value smaller than the number of turns n2 described above.

From the above experimental results, it was found that the number of turns of the coil spring should be set between n1 and n3.
In the embodiment, the number of turns is 1 to 3. This makes it possible to generate a stable frictional force without paying special attention to the mounting direction of the end point of the coil spring, and also to assemble the driving device easily.

[0062]

As described above, according to the present invention, a driving voltage is applied to an electromechanical transducer so that the electromechanical transducer expands and contracts at different speeds during expansion and contraction, and the electromechanical transducer can be moved in the expansion and contraction direction. In a driving device using an electromechanical transducer for moving a moving member frictionally coupled to a supported driving member, a coil spring is employed as a means for applying a frictional force to a contact surface between the driving member and the moving member. Things. Since the elastic force of the spring can be easily adjusted by adopting the coil spring, the magnitude of the frictional force can be reduced compared to a conventional configuration in which a frictional force is applied using a leaf spring in this type of driving device. In addition to being able to set, after determining the optimum frictional force in advance and setting the elastic force of the coil spring, it is possible to apply a stable frictional force without having to adjust the spring force in assembling the individual drive devices, In addition, the number of parts can be reduced, and assembly can be performed easily.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of a driving device according to a first embodiment.

FIG. 2 is a perspective view showing an assembled state of the driving device according to the first embodiment shown in FIG. 1;

FIG. 3 is an exploded perspective view illustrating a configuration of a driving device according to a second embodiment;

FIG. 4 is a perspective view showing an assembled state of the driving device according to the second embodiment shown in FIG. 3;

FIG. 5 is an exploded perspective view illustrating a configuration of a driving device according to a third embodiment;

FIG. 6 is an exploded perspective view showing a configuration of a driving device according to a fourth embodiment;

FIG. 7 shows a first configuration of the friction coupling portion in the first embodiment.
The perspective view which shows the modification of FIG.

FIG. 8 is a view for explaining a frictional force generated in a frictional coupling portion having the configuration shown in FIG. 7;

FIG. 9 shows a second configuration of the friction coupling portion in the first embodiment.
The perspective view which shows the modification of FIG.

FIG. 10 is a view for explaining a frictional force generated in a friction coupling portion having the configuration shown in FIG. 9;

FIG. 11 is a perspective view showing a third modification of the configuration of the friction coupling portion in the first embodiment.

FIG. 12 is a view for explaining a frictional force generated in the frictional coupling portion having the configuration shown in FIG. 11;

FIG. 13 is a perspective view showing a fourth modification of the configuration of the friction coupling portion in the first embodiment.

FIG. 14 is a view for explaining a frictional force generated in the frictional coupling portion having the configuration shown in FIG. 13;

FIG. 15 is a perspective view showing a fifth modification of the configuration of the friction coupling portion in the first embodiment.

FIG. 16 is a view for explaining a frictional force generated in a friction coupling portion having the configuration shown in FIG. 15;

FIG. 17 is a perspective view showing a sixth modification of the configuration of the friction coupling portion in the first embodiment.

FIG. 18 is a view for explaining a frictional force generated in a friction coupling portion having the configuration shown in FIG. 17;

FIG. 19 is a diagram illustrating a relationship between the number of turns of a coil spring and a generated frictional force.

FIG. 20 is a diagram showing the relationship between the number of turns of a coil spring and the variation in generated frictional force.

FIG. 21 is a diagram illustrating a relationship between the number of turns of a coil spring and a variation in frictional force due to a difference in a mounting direction of an end point of the coil spring.

FIG. 22 is an exploded perspective view of an actuator using a conventional piezoelectric element.

FIG. 23 is a perspective view showing an assembled state of the conventional actuator shown in FIG. 22;

FIG. 24 is a diagram showing an example of the waveform of a drive pulse applied to an electromechanical transducer.

[Explanation of symbols]

 Reference Signs List 11 base 11a piezoelectric element chamber 11b slider chamber 12 piezoelectric element 13 drive shaft 14 slider 15 friction member 16 output unit 17 coil spring 24 slider 25 spring fixing member 26 coil spring 31 base 32 piezoelectric element 33 driving member 36 coil spring 41 base Table 42 Piezoelectric element 43 Driving member 44 Slider 45 Spring fixing member 46 Coil spring

Claims (8)

[Claims] An electromechanical transducer having one end fixed in the direction of expansion and contraction to the base; and an electromechanical conversion element coupled to the other end of the electromechanical conversion element in the direction of expansion and contraction. A driving member movably supported on the driving member, a moving member frictionally coupled to the driving member, and supported movably in a direction of expansion and contraction of the electromechanical transducer, and a frictional force between the driving member and the moving member. And a frictional force applying means for applying the frictional force applying means, wherein the frictional force applying means is constituted by a coil spring, and the elastic force in the direction of tightening the drive member and the moving member A driving device using an electromechanical transducer, wherein a frictional force is applied to a contact surface between them. 2. The driving member has a columnar shape, the moving member includes a plurality of members obtained by dividing a cylindrical member into a plurality of members along an axial direction, and the frictional force applying means including the coil spring includes: The electromechanical transducer according to claim 1, wherein a frictional force is applied to a contact surface between the driving member and the moving member by winding up the moving member including the plurality of members with respect to the driving member. The drive used. 3. The frictional force applying means comprising the coil spring, wherein a length of contact with the moving member is shorter than a circumferential length of one turn of the coil spring. A driving device using the electromechanical conversion element. 4. The apparatus according to claim 2, wherein said moving member comprising a plurality of members and said frictional force applying means comprising a coil spring are disposed substantially coaxially with a columnar driving member. Drive device using electromechanical transducer. 5. The electromechanical converter according to claim 2, wherein the moving member has a protrusion extending along the axial direction, and the coil spring contacts the protrusion to wind up the driving member. A driving device using elements. 6. An electromechanical conversion element having a base fixed to one end of the base in the direction of expansion and contraction, and a drive voltage applied so as to expand and contract at different speeds during expansion and contraction. A driving member coupled to the other end of the electromechanical transducer in the expansion and contraction direction and supported movably in the extension and contraction direction of the electromechanical conversion element; and a frictionally coupled to the driving member and moved in the extension and contraction direction of the electromechanical transducer. A driving device using an electromechanical conversion element constituted by a movable member supported so as to be movable, wherein the moving member is constituted by a coil spring, and is frictionally coupled to the driving member by an elastic force in a winding direction. A driving device using an electromechanical conversion element. 7. The electric machine according to claim 6, wherein the driving member has a columnar shape, and the moving member formed of the coil spring is disposed substantially coaxially with the columnar driving member. A drive device using a conversion element. 8. A driving device using an electromechanical transducer according to claim 1, wherein the moving member constituted by the coil spring is a coil spring wound a plurality of times.