JP2010226940A - Linear-drive type ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear-drive type ultrasonic motor capable of attaining high drive efficiency, while realizing size reduction and high output. <P>SOLUTION: The linear-drive type ultrasonic motor includes at least: an ultrasonic oscillator having a piezoelectric element; a driven member relatively driven by a frictional force to the ultrasonic oscillator; a pressure member pressing the ultrasonic oscillator to generate a frictional force between the ultrasonic oscillator and the driven member; a plurality of spherical rolling members abutted on the driven member; and a support base member movably supporting the driven member through the rolling member, wherein the ultrasonic oscillator is provided with two drive pieces abutted against the driven member, and the plurality of rolling members are disposed at an interval such that the driven member does not enter between the two drive pieces in the driven direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a linear drive ultrasonic motor.

In an ultrasonic motor apparatus, it is effective in terms of versatility and characteristic stabilization to make a unit structure in which main constituent elements are packaged, and it is required to have a small size and high output.
As a conventional ultrasonic motor device, for example, a driving device described in Patent Document 1 can be cited (FIG. 13). Here, FIG. 13 is an exploded perspective view showing a configuration of a conventional drive device.

  A drive device 820 shown in FIG. 13 includes a drive generation unit 821, a sliding member 822, a bearing unit 823, and an urging unit 824. In this drive device 820, the vibration actuator 801 of the drive generator 821 generates drive, and the sliding member 822 (shaft 805, U-shaped base 806) that receives this drive is relative to the drive generator 821. Driven by. The bearing portion 823 is disposed to face the drive generating portion 821 with the sliding member 822 interposed therebetween, and restricts the sliding member 822 from being displaced to the side opposite to the drive generating portion 821. Further, the urging unit 824 urges the drive generating unit 821 and the bearing unit 823 in a direction in which they are brought closer to each other.

  FIG. 14 is a side view showing a schematic configuration of a driving portion of a conventional ultrasonic motor device, and shows a state before driving a piezoelectric element. An ultrasonic motor device 900 shown in FIG. 14 is a linear drive type ultrasonic motor like the drive device 820 of FIG. 13 and includes a piezoelectric element 940 (vibrator), a shaft 960, and rolling members 981, 982. And comprising. An elastic body 941 is provided on the upper surface of the piezoelectric element 940, and driver elements 942 and 943 are provided on the lower surface. The rolling members 981 and 982 are held by a guide member 970 that can move in the case of the ultrasonic motor device 900. The shaft 960 is movably mounted on the rolling members 981 and 982, and the upper side is in contact with the driver elements 942 and 943. A pressing force is applied to the piezoelectric element 940 via an elastic body 941. Further, the rolling members 981 and 982 are arranged at positions corresponding to the driver elements 942 and 943 in the X direction (the axial direction of the shaft 960, the left and right direction in FIG. 14) in the initial state before driving the piezoelectric element 940, respectively. ing.

  In the ultrasonic motor apparatus 900, when the piezoelectric element 940 is driven, predetermined vibration is transmitted to the shaft 960 via the driver elements 942 and 943. Thereby, the shaft 960 is driven so as to move relative to the piezoelectric element 940 in a direction along the axial direction. At this time, the rolling members 981 and 982 and the guide member 970 also roll and move relative to the piezoelectric element 940.

JP 2008-54459 A

  However, when the rolling elements 981 and 982 are moved relative to each other by driving the piezoelectric element 940, a part of the rolling members 981 and 982 in the X direction is provided in the piezoelectric element 940 as shown in FIG. There is a case where the position is between the two driver elements 942 and 943. Here, FIG. 15 is a side view showing a schematic configuration of a driving portion of a conventional ultrasonic motor device, and shows a state in which a part of the rolling member enters a position between the driving elements in the X direction. It is.

  When the driving elements 942 and 943 and the rolling members 981 and 982 have such a positional relationship, compared to the state in which the driving elements 942 and 943 and the rolling members 981 and 982 correspond to each other (FIG. 14), There is a problem that drive characteristics are degraded. That is, since one of the rolling members 981 and 982 is located between the two driver elements 942 and 943, the load applied to each of the rolling members 981 and 982 is not uniform, and at the same time, the piezoelectric element 940 and the shaft 960 Since the drag between the two is not symmetrical, the driving force may not be sufficiently transmitted and the driving characteristics may be deteriorated.

  In such a case, it is considered that the rolling members 981 and 982 are located between the two driver elements 942 and 943 even during the operation of the ultrasonic motor device, and therefore it is necessary to suppress the initial assembly displacement. For this reason, it has been necessary to position each member using a jig or the like when assembling the ultrasonic motor device, which makes assembly difficult.

  The present invention has been made in view of the above, and an object of the present invention is to provide a linear drive ultrasonic motor with high driving efficiency while realizing a small size and high output.

  In order to solve the above-described problems and achieve the object, the linear drive ultrasonic motor according to the present invention is relatively driven by a frictional force between an ultrasonic vibrator having a piezoelectric element and the ultrasonic vibrator. A driven member to be driven, a pressing member that presses the ultrasonic transducer such that a frictional force is generated between the ultrasonic transducer and the driven member, and a plurality of spherical rolling members that contact the driven member A linear drive type ultrasonic motor comprising at least a base member that movably supports a driven member via a rolling member, wherein the ultrasonic vibrator has two drives that contact the driven member A child is provided, and a plurality of rolling members are arranged at intervals which do not enter between two drivers in the direction in which a driven member is driven.

  In the linear drive ultrasonic motor according to the present invention, the driven member preferably has a cylindrical surface and the number of rolling members is four.

  In the linear drive ultrasonic motor according to the present invention, the connecting member that is fixed to the driven member and transmits the displacement of the driven member to the external device makes contact with the case member so that the movement distance of the driven member can be set as desired. It is preferable to have a stopper function for the distance.

  In the linear drive ultrasonic motor according to the present invention, the rolling member is guided by the guide member, whereby the interval between the rolling members in the direction in which the driven member is driven is equal to the interval between the two driver elements. It is preferable that the distance is obtained by adding a distance that the rolling member rolls in correspondence with a predetermined movement distance of the driving member.

  The linear drive ultrasonic motor according to the present invention has an effect that high drive efficiency can be realized while realizing small size and high output.

It is a perspective view which shows the structure of the linear drive type ultrasonic motor which concerns on embodiment of this invention. It is a disassembled perspective view which shows the structure of the linear drive type ultrasonic motor which concerns on embodiment of this invention. It is sectional drawing orthogonal to the width direction center of the linear drive type ultrasonic motor which concerns on embodiment of this invention. It is a conceptual diagram which shows arrangement | positioning of a case member, a drive element, a shaft, and a rolling member. It is the perspective view seen from the Z direction upper side which shows the structure of the base member of the state which accommodated the rolling member using the guide member. It is a top view of the base member of FIG. It is the side view which looked at the base member of FIG. 6 from the X direction right side. It is a disassembled perspective view which shows the structure of the linear drive type ultrasonic motor which concerns on a comparative example. It is a graph which shows the drive characteristic of the to-be-driven member when a rolling member exists inside a drive element, and when it exists outside. It is a side view showing composition of a case member and a base member of a linear drive type ultrasonic motor concerning a modification. It is sectional drawing which shows a state when the assembly | attachment of the case member which concerns on a modification, and a base member is started. It is sectional drawing which shows a state when the assembly | attachment of the case member and base member which concern on a modification is complete | finished. It is a disassembled perspective view which shows the structure of the conventional drive device. It is a side view which shows schematic structure of the drive part of the conventional ultrasonic motor apparatus, Comprising: It is a figure which shows the state before driving a piezoelectric element. It is a side view which shows schematic structure of the drive part of the conventional ultrasonic motor apparatus, Comprising: It is a figure which shows the state in which a part of rolling member entered the position between drive elements in the X direction.

Embodiments of a linear drive ultrasonic motor according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by the following embodiment.
FIG. 1 is a perspective view showing a configuration of a linear drive ultrasonic motor 100 according to the present embodiment. FIG. 2 is an exploded perspective view showing the configuration of the linear drive ultrasonic motor 100. FIG. 3 is a cross-sectional view orthogonal to the center of the linear drive ultrasonic motor 100 in the width direction (Y direction).

  As shown in FIGS. 1 to 3, the linear drive ultrasonic motor 100 includes an ultrasonic vibrator having a piezoelectric element 140 and driver elements 142 and 143, a shaft 160 as a driven member having a cylindrical surface, A member 130, four rolling members 181, 182, 183, 184, and a base member 120 are provided. In addition, the case member 110 is provided which is coupled to the base member 120 and accommodates the ultrasonic transducer and the pressing member 130 therein.

  A plate-shaped guide member 170 is disposed inside the base member 120 having a substantially U-shaped cross-sectional shape. Four notches 171, 172, 173, and 174 are formed on the side of the guide member 170. Two of these notches are provided at opposing positions on the two opposing sides of the guide member 170.

The four rolling members 181, 182, 183, 184 are accommodated in the four notches 171, 172, 173, 174, respectively, and are thereby guided by the guide member 170 to the longitudinal direction (X direction) of the base member 120. It becomes possible to move to.
Note that the number of rolling members may be more than four as long as a notch portion corresponding to the guide member 170 is provided so as to be movable in the longitudinal direction.

The shaft 160 has a side surface composed of a cylindrical surface and a flat surface, and has a substantially D-shaped longitudinal cross section. The shaft 160 is placed so that the cylindrical surface is in contact with the rolling members 181, 182, 183, and 184.
At both ends in the longitudinal direction of the shaft 160, connecting members 191 and 192 for transmitting the driving displacement of the shaft 160 to an external device are provided.

  On the other hand, the case member 110 has a box shape, and openings 111 and 112 through which the two power supply members 151 and 152 are inserted are provided on one side surface in the Y direction. Moreover, as shown in FIG. 3, the opening parts 113 and 114 which the both ends of the shaft 160 each extend outside are provided in the side surface of the both ends of a X direction.

  In the internal space of the case member 110, the pressing member 130 and the piezoelectric element 140 are included sequentially from the upper side in the Z direction. The protrusions 115 and 116 provided at the lower four corners of the case member 110 are engaged with the engagement portions 121 and 122 provided along the X direction on the upper portion of the base member 120, respectively. 110 are fixed to each other.

  As shown in FIG. 3, when the case member 110 is assembled to the base member 120, the driver elements 142 and 143 come into contact with a plane located above the shaft 160 and the pressing member 130 is bent by a predetermined amount. In this state, the substantially central portion in the longitudinal direction comes into contact with the support member 141. The amount of bending of the pressing member 130 can be arbitrarily set according to the protruding shape of the inner wall convex portions 117 and 118 of the case member 110 with which both ends in the longitudinal direction of the pressing member 130 abut and the position of the support member 141. By setting the amount of bending of the pressing member 130 to a desired value, a desired pressing force is generated from the piezoelectric element 140 to the shaft 160, and the driver elements 142 and 143 are urged to the shaft 160. As a result, a frictional force is generated between the driver elements 142 and 143 and the shaft 160, and the shaft 160 can move in the longitudinal direction (x direction, driving direction) with respect to the base member 120 by driving the piezoelectric element 140. It becomes.

  In the linear drive ultrasonic motor 100 configured as described above, when the shaft 160 is driven in the longitudinal direction (x direction) while being pressed toward the base member 120, the rolling members 181, 182, 183, 184 are Rolling motion is received by the driving force in the longitudinal direction of the shaft 160 at the contact point with the shaft 160.

  Further, the connecting members 191 and 192 are fixed to both end portions of the shaft 160. Fixing is performed by screwing or bonding, for example. Thereby, the displacement of the shaft 160 is transmitted to an external device coupled to the connecting members 191 and 192.

  The connecting members 191 and 192 have a stopper function of restricting the moving distance in the longitudinal direction of the shaft 160 to a desired distance by contacting the case member 110. More specifically, in the linear drive ultrasonic motor 100 of the present embodiment, as shown in FIG. 4, the longitudinal center of the shaft 160 is positioned at the center position in the X direction of the piezoelectric element 140 (position C in FIG. 4). The connecting members 191 and 192 are spaced apart from the case member 110 by a distance L at the initial position. That is, the shaft 160 can move in the X direction from the initial position by a distance L until the connecting members 191 and 192 come into contact with the case member 110, respectively. Here, FIG. 4 is a conceptual diagram showing the arrangement of the case member 110, the driver elements 142 and 143, the shaft 160, and the rolling members 181 and 182. The distance L that the shaft 160 can move may be defined as the distance between each of the connecting members 191 and 192 and the base member 120.

  Note that the base member 120 can be used instead of the case member 110 as the contact point of the connecting members 191 and 192 as long as it functions as a stopper of the shaft 160.

  In the linear drive ultrasonic motor 100, the four rolling members 181, 182, 183, 184 are arranged at intervals so as not to enter between the two drive elements 142, 143 in the X direction in which the shaft 160 is driven. Has been. Hereinafter, the positional relationship between the rolling members 181, 182, 183, 184 and the two driver elements 142, 143 will be described in detail with reference to FIGS. 5 to 7. FIG. 5 is a perspective view showing the configuration of the base member 120 in a state where the rolling members 181, 182, 183, 184 are accommodated using the guide member 170, as viewed from the upper side in the Z direction. FIG. 6 is a plan view of the base member 120 of FIG. FIG. 7 is a side view of the base member 120 of FIG. 6 viewed from the right side in the X direction.

  First, a protrusion 123 extending along the X direction is formed at the center of the bottom surface inside the base member 120. In addition, position restricting portions 124 are formed at both ends in the X direction on the bottom surface inside the base member 120 so as to face each other in the Y direction. The protrusion 123 protrudes above the Y direction both ends where the rolling members 181, 182, 183, and 184 abut, that is, toward the guide member 170. By providing the protrusion 123 in this manner, the sliding resistance can be reduced by limiting the contact area between the guide member 170 and the bottom surface of the base member 120. Further, since the guide member 170 moves at a position higher than the bottom surface where the rolling members 181, 182, 183, and 184 abut by the height of the protruding portion 123, when the rolling members 181, 182, 183, and 184 roll. Riding on the guide member 170 can be prevented.

  Further, in the X direction, the interval between the notch 171 provided on one side of the guide member 170 and the notch 172 and the notch 173 provided on the other side of the guide member 170 are notched. The distance from the part 174 is L ′. Accordingly, the spacing between the rolling member 181 and the rolling member 182 and the spacing between the rolling member 183 and the rolling member 184 respectively accommodated in the notches 171, 172, 173 and 174 are also L ′. It becomes.

  On the other hand, the interval between the driver 142 and the driver 143 in the X direction is A. The distance L ′ between the rolling member 181 and the rolling member 182 and the distance L ′ between the rolling member 183 and the rolling member 184 are sufficiently larger than the distance A between the driving element 142 and the driving element 143. Is set.

When the shaft 160 is driven in the X direction, the rolling members 181, 182, 183, and 184 roll and move, and the guide member 170 also moves simultaneously. The rolling members 181, 182, 183, and 184 are in contact with the inner bottom surface of the base member 120 at one point and roll while in contact with the inner side surface at one point. In such a configuration, the movement distance of the shaft 160 in the X direction is L / 2 ^1/2 at the maximum in the movement in one of the X directions.

In the linear drive ultrasonic motor 100, the distance L ′ between the rolling member 181 and the rolling member 182 in the X direction in which the shaft 160 is driven (interval between the rolling member 183 and the rolling member 184) L ′ is two. Guidance is made so that the distance A between the driver elements 142 and 143 is larger than twice the distance that the rolling member rolls corresponding to the maximum movement distance L / 2 ^1/2 (predetermined movement distance) of the shaft 160. Notches 171, 172, 173, and 174 are arranged on the member 170, respectively.

  The initial assembly position of the guide member 170 to the base member 120 is not always the neutral position in the X direction. In other words, depending on the initial assembly position of the guide member 170, the intermediate position between the rolling member 181 and the rolling member 182, the intermediate position between the rolling member 183 and the rolling member 184, and the drive element 142 and the drive The intermediate position with the child 143 may not be the same. For this reason, it is desirable to take a large L 'in consideration of the positional deviation.

  On the other hand, when the distance L ′ is significantly increased, it is necessary to increase the size of the base member 120 in the X direction, which leads to an increase in the size of the linear drive ultrasonic motor 100, which is generally acceptable. It is advisable to increase the amount of misalignment during assembling.

As described above, in the X direction, the shaft 160 is moved by the predetermined moving distance L / 2 ¹ by disposing the interval L ′ of the rolling members 181, 182, 183, 184 sufficiently wider than the interval A of the driver elements 142, 143. Even when it has moved by ^{/ 2,} it is possible to prevent the rolling members 181, 182, 183, 184 from moving between the two drive elements 142, 143, thereby preventing deterioration of drive characteristics. .

  Here, with reference to FIG. 8, FIG. 9, the difference in the drive characteristic of the to-be-driven member when the rolling member is inside and outside the driving element in the X direction will be described. FIG. 8 is an exploded perspective view showing a configuration of a linear drive ultrasonic motor 200 according to a comparative example. FIG. 9 is a graph showing the driving characteristics of the driven member when the rolling member is inside (square mark) and outside (circle mark) than the driving element. The horizontal axis in FIG. 9 is the driving frequency (Hz) of the piezoelectric element 140, and the vertical axis is the moving speed (mm / s) of the shaft 160 driven by the piezoelectric element 140.

  The linear drive ultrasonic motor 200 according to the comparative example is different from the linear drive ultrasonic motor 100 according to the above-described embodiment in that the connecting members 191 and 192 are not fixed to both ends of the shaft 160. In addition, a method for supplying power to the piezoelectric element 140 is not particularly limited, and the case member 210 is simply displayed.

  Since the linear drive ultrasonic motor 200 is not provided with the connecting members 191 and 192 that perform the stopper function, the rolling members 181, 182, 183, and 184 are rotated to arbitrary positions by driving the shaft 160. The moving member may enter between the driver elements.

  In FIG. 9, when the rolling member is inside the driver (square mark), in the linear drive ultrasonic motor 200, the two rolling members 181, 182, 183, and 184 that are opposed to each other are rotated. The driving characteristics when the moving member enters between the two driving elements 142 and 143 in the X direction are shown.

  On the other hand, in FIG. 9, when the rolling member is outside the driver (circle), in the linear drive ultrasonic motor 200, all of the four rolling members 181, 182, 183, 184 are X In the direction, the drive characteristics when not between the two driver elements 142 and 143 are shown. This drive characteristic is such that the four rolling members 181, 182, 183, 184 are arranged so that all of the four rolling members 181, 182, 183, 184 do not enter between the two drive elements 142, 143. Corresponding to 100.

  As shown in FIG. 9, when the rolling member is outside the driver (circle), the moving speed obtained in the entire driving frequency is when the rolling member is inside the driver (square). It can be seen that the driving characteristics are high.

  Next, a modified example will be described with reference to FIGS. FIG. 10 is a side view showing the configuration of the case member 310 and the base member 320 of the linear drive ultrasonic motor according to the modification. FIG. 11 is a cross-sectional view showing a state when assembly of the case member 310 and the base member 320 according to the modification is started. FIG. 12 is a cross-sectional view showing a state when the assembly of the case member 310 and the base member 320 according to the modification is finished. In FIG. 10, illustration of members other than the case member 310 and the base member 320 is omitted. In addition, in FIGS. 11 and 12, the detailed configuration inside the case member 310 is not shown.

  In the linear drive ultrasonic motor according to the modification, the slide grooves 311 and 312 are provided in the case member 310, and the locking portions 321 and 322 are provided in the base member 320. Different from the sonic motor 100. Since the configuration other than this is the same as that of the linear drive ultrasonic motor 100 according to the above-described embodiment, the detailed description thereof is omitted, and the same reference numerals are given to the same members.

  The locking portions 321 and 322 are protrusions extending in the Y direction (a direction perpendicular to the X direction and the Z direction) from the upper portion of the side wall 323 extending in the X direction of the base member 320. The locking portions 321 and 322 are arranged at predetermined positions so as to be separated from each other in the X direction.

  The slide grooves 311 and 312 are formed in the lower part of the wall part 313 orthogonal to the Y direction (direction perpendicular to the paper surface of FIGS. 10 to 12) among the wall parts constituting the case member 310. The slide grooves 311 and 312 have substantially the same inverted L-shaped groove shape in a side view, and one end is an opening 311a and 312a formed so as to extend upward from the lower surface of the case member 310. The other end is a recess 311b, 312b that extends downward from the path extending in the X direction from the openings 311a, 312a. The openings 311a and 312a are formed at the same interval as the locking portions 321 and 322. Further, the distance that the locking portions 321 and 322 can move in the X direction in the slide grooves 311 and 312 is L.

  The case member 310 and the base member 320 are assembled by first inserting the locking portions 321 and 322 from the openings 311a and 312a, respectively, and the upper surfaces of the locking portions 321 and 322 abut against the inner walls of the slide grooves 311 and 312. The case member 310 and the base member 320 are relatively moved in the Z direction until they come into contact with each other. When the upper surfaces of the locking portions 321 and 322 are in contact with the inner walls of the slide grooves 311 and 312, one of the position restricting portions 324 provided at both ends in the X direction of the base member 320 is connected to the connecting member 192 as shown in FIG. Abut.

  Next, the locking portions 321 and 322 are moved in the X direction within the slide grooves 311 and 312. When the locking portions 321 and 322 move by the distance L, the locking portions 321 and 322 reach positions where they can be fitted into the recesses 311b and 312b. Here, when the case member 310 and the base member 320 are relatively moved in the Z direction and the locking portions 321 and 322 are fitted in the recesses 311b and 312b, the case member 310 and the base member 320 are relatively moved in the X direction. Is regulated and assembly is completed. At this time, as shown in FIG. 12, the center positions of the case member 310 and the base member 320 in the X direction coincide with each other.

  In the linear drive ultrasonic motor according to the modified example, the case member 310 and the base member 320 are simply moved relative to each other so that the locking portions 321 and 322 are moved along the shapes of the slide grooves 311 and 312. In particular, the positions of the case member 310 and the base member 320 can be aligned easily and reliably, and assembly displacement can be suppressed.

  As described above, the linear drive ultrasonic motor according to the present invention is suitable for high-precision driving of small devices.

DESCRIPTION OF SYMBOLS 100 Linear drive type ultrasonic motor 110 Case member 111,112,113,114 Opening part 115,116 Protrusion part 117,118 Inner wall convex part 120 Base member 121,122 Locking part 123 Protruding part 130 Pressing member 140 Piezoelectric element 141 Support Member 142, 143 Driver 151, 152 Power supply member 160 Shaft 170 Guide member 171, 172, 173, 174 Notch 181, 182, 183, 184 Rolling member 191, 192 Connecting member 200 Linear drive ultrasonic motor 210 Case Member 310 Case member 311 Slide groove 311a Opening portion 311b Recessed portion 312 Slide groove 312a Opening portion 312b Recessed portion 313 Wall portion 320 Base member 321, 322 Locking portion 323 Wall portion 324 Position restricting portion

Claims (4)

An ultrasonic transducer having a piezoelectric element;
A driven member that is relatively driven by a frictional force with the ultrasonic transducer;
A pressing member that presses the ultrasonic transducer so that a frictional force is generated between the ultrasonic transducer and the driven member;
A plurality of spherical rolling members in contact with the driven member;
A base member that movably supports the driven member via the rolling member;
In a linear drive ultrasonic motor comprising at least
The ultrasonic transducer is provided with two driving elements that come into contact with the driven member,
The linearly driven ultrasonic motor, wherein the plurality of rolling members are arranged at intervals that do not enter between the two driver elements in a direction in which the driven member is driven.   The linearly driven ultrasonic motor according to claim 1, wherein the driven member has a cylindrical surface and the number of rolling members is four. A case member that houses the ultrasonic transducer and the pressing member;
A coupling member fixed to the driven member and transmitting the displacement of the driven member to an external device;
The linear drive ultrasonic wave according to claim 1, wherein the connecting member has a stopper function that makes a moving distance of the driven member a desired distance by contacting the case member. motor.   The rolling member is guided by a guide member, so that the distance between the rolling members in the direction in which the driven member is driven is equal to the distance between the two driver elements and the predetermined moving distance of the driven member. The linear drive ultrasonic motor according to any one of claims 1 to 3, wherein a distance corresponding to a rolling distance of the rolling member is correspondingly added.

Images