JP2010094004A - Spherical motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spherical motor actuated by a novel mechanism using a piezoelectric element as a driving source. <P>SOLUTION: Four pieces of supporting pedestals 14 are fixedly disposed on the surface of a base 12 at the interval of a uniform angle in the circumferential direction. Each of the piezoelectric elements 11 is housed in each of the supporting pedestals 14, and the piezoelectric element 11 extends in the longitudinal direction by applying voltage. A recess 16 is formed on the upper part of the supporting pedestal 14, respectively. A cylindrical roller 18 is movably arranged sideways in the vertical direction at the recess 16. The roller 18 is fixedly mounted on the piezoelectric element 11. The lower side of a big ball 20 is supported at its four points on the four pieces of rollers 18. The big ball 20 is supported from the upper side by an elastic pressing member constituted by a blade spring 30, a small ball 48, a sliding bar 38, a coil spring 46 and the like. Each of the piezoelectric elements 11 is selectively actuated by a rectangular wave, a saw-tooth wave, and the like. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spherical motor that operates by a novel mechanism using a piezoelectric element as a drive source.

  The spherical motor is a motor that rotationally drives a spherical body having a spherical surface in the spherical direction. As spherical motors using piezoelectric elements as drive sources, there are those described in Patent Documents 1 to 3 below. In the spherical motor described in Patent Document 1, four projecting members are erected on an elastic body constituting a base, the sphere is supported by the projecting member at four points, and a plurality of piezoelectric members are attached to the elastic body at positions between the projecting members. By arranging the elements and driving the plurality of piezoelectric elements at high frequencies having different phases, longitudinal vibration and bending vibration are generated in the elastic body, and the sphere is rotated by combining both vibrations.

  In the spherical motor described in Patent Document 2, a sphere (rotor) is surrounded and supported by three or four stators each having a piezoelectric element attached thereto, and a two-phase high-frequency voltage is applied to each piezoelectric element to thereby each stator. A traveling wave is generated on the surface of the sphere to rotate the sphere.

  The spherical motor described in Patent Document 3 supports a spherical body via a friction material on one piezoelectric element, and the piezoelectric element is driven by an alternating signal to bend repeatedly in the lateral direction to cause the rotational force in the circumferential direction to the spherical body. At this time, by using signals with different rising and falling speeds as the alternating signal, the sliding of the friction material and the sphere is made different at the rising and falling of the alternating signal, thereby rotating the sphere in one direction. It is made to let you.

JP-A-9-219980 JP-A-11-84526 JP 2006-238644 A

  The present invention provides a spherical motor that uses a piezoelectric element as a drive source and operates by a mechanism different from those described in Patent Documents 1 to 3.

  The present invention is supported by the base in a state in which the base and the circumferential direction are spaced apart from each other at an appropriate angular interval, and each is extended by applying a voltage, and the application of the voltage is canceled to release the original. A plurality of three or more piezoelectric elements returning to length and supported by each of the piezoelectric elements to move according to the extension of each piezoelectric element, and to return to the original length as the piezoelectric element returns to its original length. And a spherical body having a spherical surface and supported by a plurality of points by the plurality of movable bodies, and each of the movable bodies supports the spherical body. In terms of position, the moving direction of the moving body includes a tangential direction component of the spherical body. According to the present invention, by selectively driving a plurality of piezoelectric elements, a tangential rotational force is applied to the spherical body, and the spherical body rotates.

  The present invention may further include an elastic pressing member that elastically presses and supports the spherical body from the opposite side of the center of the plurality of points supported by the plurality of moving bodies. According to this, the spherical body can be rotated while being stably held.

  In the present invention, the moving body can be constituted by a roller, a sphere or the like. In the present invention, for example, four moving bodies can be arranged at equal angular intervals in the circumferential direction. In this case, the four moving bodies can be arranged on the same plane, for example. Alternatively, the four moving bodies can be arranged on different planes for each opposed pair. The piezoelectric element can be driven by a repetitive signal such as a rectangular wave or a sawtooth wave.

  Embodiments of the present invention are shown in FIG. 1, FIG. 2, and FIG. 1 is a cross-sectional front view (cross-sectional view taken along the line AA in FIG. 2), FIG. 2 is a plan view, and FIG. 3 is a plan view of the leaf spring 30 (shown in the position taken along the line BB in FIG. 1). The spherical motor 10 is entirely made of metal, for example, except for the piezoelectric element 11. The spherical motor 10 includes a disk-shaped base 12. Although FIG. 1 shows the posture in which the base 12 is horizontally disposed, the posture when the spherical motor 10 is used is not limited to this and can be used by being tilted. On the surface 12b of the base 12, four support bases 14 are arranged at equal angular intervals in the circumferential direction on the same circumference centered on the central axis 12a of the base 12, and fixed by screws or the like. Alternatively, the support base 14 can be configured integrally with the base 12. Each support base 14 is arranged in a direction facing the central axis 12 a of the base 12.

  Each support base 14 has a hole 14a in a direction perpendicular to the base surface 12b (a direction parallel to the central axis 12a). In each hole 14a, four piezoelectric elements 11 (11A, 11B, 11C, and 11D) of the same product (that is, the same shape and the same characteristics) are detachably accommodated. Each piezoelectric element 11 extends in the longitudinal direction (a direction parallel to the central axis 12a) by applying a voltage, and returns to its original length by releasing the application of the voltage. Since the lower end surface 11a of the piezoelectric element 11 is in contact with and locked to the base surface 12b, the upper end surface 11b of the piezoelectric element 11 is displaced upward (in a direction parallel to the central axis 12a) when a voltage is applied. When the application of the voltage is canceled, the piezoelectric element 11 returns to its original length, and the upper end surface 11b is displaced downward and returns to its original position.

  A recess 16 is formed in the upper part of each support base 14. The recess 16 is open in the direction facing the central axis 12a and above. The upper end surface 11b of the piezoelectric element 11 is formed on the same plane as the bottom surface 16a of the recess 16 or at a position slightly protruding from the bottom surface 16a so that a roller 18 described later is always in contact. The rear wall 16b and both side walls 16c, 16c of the recess 16 are formed perpendicular to the base surface 12b. Both side walls 16c, 16c have their upper edges cut obliquely upward as shown in FIG. 1 so as not to collide with a large sphere 20 described later.

  In each recess 16 is a cylindrical roller 18 (18A, 18B, 18C, 18D) of the same member (that is, the same material and the same shape) as a moving body in the vertical direction (the extension / return direction of the piezoelectric element 11, that is, the central axis 12a). In a direction parallel to the horizontal direction). The left and right end surfaces of the roller 18 are locked by both side walls 16c, 16c of the recess 16, and the movement of the roller 18 in the axial direction is restricted. Further, the outer peripheral surface of the roller 18 is locked by the rear wall 16b of the recess 16 to restrict the movement of the roller 18 in the outward direction (radial direction with respect to the central axis 12a). The roller 18 is placed on the piezoelectric element 11 with the lower surface of the outer peripheral surface being in contact with the upper end surface 11 b of the piezoelectric element 11. The upper end surfaces 11 b of the four piezoelectric elements 11 are on the same plane 13, whereby the four rollers 18 are arranged on the same plane 13. Four lower surfaces of the large sphere 20 are equally supported on the four rollers 18 as spherical bodies. Each roller 18 is stably supported on the piezoelectric element 11 in the recess 16 by the pressing force received from the large sphere 20. Each piezoelectric element 11 is stably held in the hole 14a by the pressing force received from each roller 18 with the lower end surface 11a in contact with the base surface 12b.

  On the surface 12b of the base 12, two struts 22 and 24 are vertically fixed by screws 26 and 28 at positions symmetrical to the central axis 12a. As shown in FIG. 2, the support columns 22 and 24 are disposed at a position intermediate between the support bases 14. A leaf spring 30 is placed on the tops of the columns 22 and 24. As shown in FIG. 3, the leaf spring 30 is provided with a small-diameter hole 30a (screw through hole) in the vicinity of one end near the support 22 and a large-diameter hole 30b in the vicinity of the other end near the support 24. Has been established. Short pipes 32 and 34 (FIG. 1) are arranged coaxially with the columns 22 and 24 from above the leaf spring 30. The diameter of the small-diameter hole 30a of the plate spring 30 is smaller than the outer diameter of either the column 22 or the short tube 32 at the position on the column 22 side, and the plate spring 30 is sandwiched between the column 22 and the short tube 32. A small-diameter portion 34 a is formed in the lower portion of the short tube 34 at a position on the column 24 side. The diameter of the large-diameter hole 30b of the leaf spring 30 is smaller than the outer diameter of the column 24 and larger than the outer diameter of the small-diameter portion 34a of the short pipe 34. Therefore, the small diameter portion 34a of the short pipe 34 is passed through the hole 30b of the leaf spring 30 so as to be movable in the axial direction. The lower end surface of the short tube 34 abuts on the upper end surface of the column 24.

  As shown in FIG. 1, the upper base 36 is placed on the short tubes 32 and 34. Screws 37 and 39 are inserted from above the upper base 36 through the upper base 36, the short pipes 32 and 34, and the leaf spring 30, and screwed into the screw holes 22a and 24a at the upper ends of the columns 22 and 24, whereby the upper base 36, the short pipes 32 and 34, and the leaf spring 30 are fixed to the columns 22 and 24. At this time, the leaf spring 30 is sandwiched and fixed between the support 22 and the short tube 32 on the support 22 side, and is guided to the small diameter portion 34a of the short tube 34 on the support 24 side, as indicated by an arrow C in FIG. Can bend in the vertical direction. That is, the leaf spring 30 is cantilevered on the column 22 side so as to bend up and down.

  A cylindrical portion 36a is formed at the center of the upper base 36 coaxially with the central shaft 12a. A cylindrical slide bar 38 is accommodated in the internal space 36b of the cylindrical portion 36a so as to be movable in the direction of the central axis 12a. The lower part 38b of the slide bar 38 is formed with a large diameter, and is accommodated in the cylindrical part 36a with a slight gap. As a result, the slide bar 38 is prevented from being inclined with respect to the central axis 12a and the lower end surface of the slide bar 38 being laterally displaced. A disc-like plate material 40 for retaining is attached to the top of the slide bar 38 with screws 44. A coil spring 46 is accommodated in the internal space 36b of the cylindrical portion 36a so as to surround the outer peripheral surface of the slide bar 38. The upper end portion of the coil spring 46 is locked to the ceiling surface of the cylindrical portion 36 a, and the lower end portion of the coil spring 46 is locked to the upper surface of the large-diameter lower portion 38 b of the slide bar 38. The coil spring 46 applies a force that moves downward (in the direction toward the center of the large sphere 20) along the central axis 12 a to the slide bar 38. A recess 38a is formed at the center of the lower end surface of the slide bar 38, and a small ball 48 is accommodated therein. The small ball 48 presses the leaf spring 30 by the urging force of the coil spring 46. As a result, the leaf spring 30 bends downward, contacts the top of the large sphere 20 with a predetermined pressing force on the central axis 12a, and places the large sphere 20 on the upper side (opposite the center of the four-point support by the four rollers 18). Support from. Due to the support from the upper side of the large sphere 20, the four-point support of the large sphere 20 from the lower side by the four rollers 18 is stably held even when the spherical motor 10 is used in a posture inclined with respect to the horizontal. . The pressing force applied to the large sphere 20 by the elastic pressing member (the leaf spring 30, the slide bar 38, the coil spring 46, and the small sphere 48) is large enough that each piezoelectric element 11 can expand and the large sphere 20 can rotate by the expansion. Set to

  In addition, the leaf | plate spring 30 is arrange | positioned in order to rotate the large sphere 20 stably. That is, when the large sphere 20 and the small sphere 48 are in direct contact with each other, the piezoelectric element 11 is driven and the center of the large sphere 20 is once displaced from the central axis 12a (the center of the large sphere 20 in FIG. The position of the large sphere 20 returns from the position o1 to the position o0 due to the meshing of the large sphere 20 and the small sphere 48 when the drive of the piezoelectric element 11 is subsequently released. There may be no phenomenon. As a countermeasure against this phenomenon, the leaf spring 30 is arranged between the large sphere 20 and the small sphere 48 to prevent the engagement between the large sphere 20 and the small sphere 48 and when the driving of the piezoelectric element 11 is released. The center of the large sphere 20 can smoothly return from the position o1 to the position o0 (a state in which the center of the large sphere 20 in FIG. 8 described later returns from the position o1 to the position o0). If the rotation of the large sphere 20 is guaranteed even if the small sphere 48 is eliminated and the lower end surface (flat surface) of the slide bar 38 is brought into direct contact with the large sphere 20, the large sphere 20 and the small sphere 48 Therefore, the leaf spring 30 can be omitted.

  The spherical motor 10 configured as described above can rotationally drive the large sphere 20 in a corresponding direction by repeatedly applying a signal to any of the four piezoelectric elements 11 (11A, 11B, 11C, 11D). it can. That is, when the piezoelectric element 11 is extended by driving the piezoelectric element 11, the roller 18 moves upward (a direction perpendicular to the plane 13 on which the four rollers 18 are arranged). 20 is shifted from the direction toward the center of the roller 20, the roller 18 and the large ball 20 are in contact with each other at a position where the roller 18 moves in the tangential direction component of the large ball 20 (the amount of movement of the four rollers 18 upward). Are equal to each other, the tangential components of the four rollers 18 are equal to each other). Due to the tangential direction component of the moving direction of the roller 18, a rotational force is applied to the large sphere 20 (the four rollers 18 generate the same rotational force), and the large sphere 20 rotates. The rotation axis of the rotation of the large sphere 20 is in a position parallel to the plane 13 on which the four rollers 18 are arranged, passing through the center of the large sphere 20, and for each adjacent roller 11 as viewed from the direction of the central axis 12a. It is shifted by 90 degrees. Therefore, the rotation direction of the large sphere 20 by the roller pair 11A, 11B in the opposite position is opposite to each other, the rotation direction of the large sphere 20 by the other roller pair 11C, 11D in the opposite position is opposite to each other, and The rotation direction of the large sphere 20 by the roller pair 11A, 11B and the rotation direction of the large sphere 20 by the roller pair 11C, 11D are shifted from each other by 90 degrees. Accordingly, by appropriately driving the four piezoelectric elements 11, the large sphere 20 can be rotated and any point on the surface of the large sphere 20 can be directed in any direction. Since the large sphere 20 operates in this manner, the angle of the angle adjustment target can be arbitrarily adjusted by connecting an appropriate angle adjustment target to the large sphere 20. For example, a rectangular wave as shown in FIG. 4A or a sawtooth wave as shown in FIG. 4B can be used as the driving repetitive signal.

  The operation of the spherical motor 10 of FIG. 1 will be described with reference to FIGS. 5 to 9 show an operation for one stroke when the piezoelectric element 11A is driven by one wave of a repetitive signal to rotate the large sphere 20 by a predetermined angle in the counterclockwise direction in the drawing. 5 to 9 schematically show the spherical motor 10 of FIG. The upper support of the large sphere 20 is illustrated in a simplified manner so that the slide bar 38 urged downward by the coil spring 46 directly contacts and presses the large sphere 20. FIG. 5 shows a state before the operation. At this time, the center of the large sphere 20 is defined as o0, and the positions where the outer peripheral surface of the large sphere 20 contacts the rollers 18A, 18B and the slide bar 38 are defined as Pa0, Pb0, and Pe0, respectively. The large sphere 20 is supported at four points by four rollers 18 and is held in a wedge state. At this time, since the slide ball 38 is in contact with the large sphere 20 from above, the holding torque works and the stationary state is maintained. Therefore, no electric power is required to keep the stationary state.

  FIG. 6 shows a state when one wave of a signal applied to the piezoelectric element 11A rises and the piezoelectric element 11A expands. The extension amount of the piezoelectric element 11A at this time is represented by Δu. When the piezoelectric element 11A is extended by Δu, the roller 18A placed thereon is also pushed upward by the same amount Δu. At this time, since the outer peripheral surface of the roller 18A is in contact with the rear wall 16b of the recess 16, the roller 18A moves in the vertical direction (direction parallel to the central axis 12a). The position of the roller 18B does not change. When the roller 18A moves upward, the contact point Pa0 of the large sphere 20 that is in contact with the roller 18A is pushed upward. Since this push-up direction deviates from the direction toward the center o0 (center of gravity) of the large sphere 20, this push-up force includes a tangential direction component of the large sphere 20 at the contact point Pa0. The large sphere 20 rotates counterclockwise by the force component in the tangential direction. At this time, the rotational movement distance between the points Pa0 and Pa1 on the surface of the large sphere 20 is approximately Δu. When the large sphere 20 rotates, slip occurs on the contact surface between the large sphere 20 and the roller 18B and the contact surface between the large sphere 20 and the slide bar 38. Due to the upward movement and rotation by pushing up the large sphere 20, the positions o0, Pa0, Pb0 and Pe0 in FIG. 5 move to the positions o1, Pa1, Pb1 and Pe1 in FIG. 6, respectively.

  FIG. 7 shows a state before a roller 18A returns to its original position after one wave of a signal applied to the piezoelectric element 11A falls and the piezoelectric element 11A returns to its original length.

  FIG. 8 shows a state where the roller 18A has returned to its original position. The large sphere 20 tends to move downward by its own weight and the downward pressing force of the slide bar 38 biased by the coil spring 46. At this time, since the inertia of the large sphere 20 remains in the counterclockwise direction, the rotation of the large sphere 20 does not return to the clockwise direction, and the respective contact surfaces of the rollers 18A and 18B and the slide bar 38 are slipped while maintaining the rotation angle. Resulting in translation. By this parallel movement, the positions o1, Pa1, Pb1, and Pe1 in FIG. 7 move to the positions o0, Pa2, Pb2, and Pe2 in FIG. 8, respectively. Thus, the operation by one wave of the repetitive signal is completed.

  FIG. 9 shows changes in the rotational angle position of the large sphere 20 before and after driving due to one wave of the repetitive signal by the above operation. The large sphere 20 rotates the angle φ with one wave of the repetitive signal, and the positions of Pa0, Pb0, Pe0 before driving move to Pa2, Pb2, Pe2 after driving, respectively. The rotational movement distance on the surface of the large sphere 20 is substantially equal to the extension amount Δu of the piezoelectric element 11A. By continuously driving with the repetitive signal, the large sphere 20 can be continuously rotated in the direction of the rotation angle corresponding to “φ × wave number of the repetitive signal”. Therefore, for example, by connecting and driving the rotation angle adjustment target to the large sphere 20, the rotation angle of the rotation angle adjustment target can be adjusted to an arbitrary angle.

  Although the case where the piezoelectric element 11A is driven has been described above, the same applies to the case where the other piezoelectric elements 11B, 11C, and 11D are driven, and the rotation direction of the large sphere 20 can be changed depending on which one is driven. Further, by driving adjacent piezoelectric elements simultaneously or alternately, the large sphere 20 can be rotated in the middle direction of the rotation direction by the single drive.

  In the above embodiment, the large sphere 20 is supported from the upper side by the elastic pressing member (the leaf spring 30, the slide bar 38, the coil spring 46, and the small sphere 48), but the spherical motor used only in a horizontal posture is used. In this case, support from the upper side by the elastic pressing member can be omitted. FIG. 10 shows another embodiment of the spherical motor configured as described above. This spherical motor 50 is the same as the spherical motor 10 shown in FIG. 1 except that the columns 22, 24, leaf springs 30, short tubes 32, 34, upper base 36, screws 26, 28, 37, 39, slide rods 38, small balls 48, coil springs. 46, the disk-shaped plate material 40, and the screw 44 are removed. The large sphere 20 is supported at four points by rollers 18 (18A, 18B, 18C, 18D) from below. The driving method of the piezoelectric element 11 and the operations of the roller 18 and the large sphere 20 by the driving method are the same as those in the embodiment of FIG. However, since there is no elastic pressing member, the large sphere 20 moves downward only by its own weight when the drive signal of the piezoelectric element falls. Although the spherical motor 50 is supported only on the lower side, it is used in a horizontal posture, so that the large sphere 20 can rotate while maintaining a state where it is stably supported at four points by the roller 18.

  In the above embodiment, the four rollers 18A, 18B, 18C, and 18D are arranged on the same circumference (on the same plane 13 (FIG. 1)), but the present invention is not limited to this. For example, one opposing roller pair 18A, 18B is arranged on one same circumference (on one same plane), and the other opposite roller pair 18C, 18D is arranged on another same circumference (on another same plane). ) Can be arranged. An example of such an arrangement is shown in FIG. The same reference numerals are used for parts common to the embodiment of FIGS. FIG. 11 shows only a part of the base 12, the piezoelectric element 11, the roller 18, and the large sphere 20, and other configurations are omitted. One roller pair 18A, 18B which opposes is arrange | positioned on the same periphery 52a (on the same plane 52b). The other pair of rollers 18C and 18D facing each other is arranged on another same circumference 54a (on another same plane 54b). With such an arrangement, the roller pair 18A, 18B and the roller pair 18C, 18D have different large spherical tangential components of the movement amount of the roller 18 at the contact position between the roller 18 and the large ball 20. The rotation angle of the large sphere 20 per driving is different.

  In each of the embodiments, a roller is used as the moving body. However, a small sphere can be used instead of the roller. In each of the above embodiments, the entire sphere (large sphere 20) is used as the spherical body. However, when the rotational angle of the spherical body is limited, the entire sphere is not necessary, and a hemisphere or the like can be used. In each of the above embodiments, four piezoelectric elements are used. However, three or five or more piezoelectric elements can be arranged at equal angular intervals in the circumferential direction.

It is a figure which shows embodiment of this invention, and is AA arrow sectional drawing of FIG. It is a top view of the spherical motor of FIG. It is a top view of the leaf | plate spring 30, and is shown by the BB arrow position of FIG. It is a wave form diagram which shows the specific example of the repetition signal used for the drive of the spherical motor of FIG. It is operation | movement explanatory drawing of the spherical motor of FIG. 1, and shows the state before operation | movement. It is operation | movement explanatory drawing of the spherical motor of FIG. 1, and shows the state when one wave of the repetitive signal applied to a piezoelectric element rises, and a piezoelectric element expand | extends. FIG. 2 is an explanatory diagram of the operation of the spherical motor in FIG. 1 and shows a state before a roller returns to its original position after one wave of a repetitive signal applied to the piezoelectric element falls and the piezoelectric element returns to its original length. It is operation | movement explanatory drawing of the spherical motor of FIG. 1, and shows a state when a roller returns to the original position. It is operation | movement explanatory drawing of the spherical motor of FIG. 1, and the change of the rotation angle position of the large sphere before a drive by the operation | movement of FIGS. It is sectional drawing which shows other embodiment of this invention. It is the front view and top view which show embodiment which has arrange | positioned four rollers on a separate plane for every roller pair which opposes.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,50 ... Spherical motor, 11 (11A, 11B, 11C, 11D) ... Piezoelectric element, 12 ... Base, 13 ... Plane on which four rollers are arranged, 18 (18A, 18B, 18C, 18D) ... Roller (moving) Body), 20 ... large sphere (spherical body), 30, 38, 46, 48 ... elastic pressing member, 52b ... plane on which one opposing roller pair is arranged, 54b ... plane on which the other opposing roller pair is arranged

Claims (7)

Base and
3 or more which are supported by the base in a state where they are arranged at an appropriate angular interval in the circumferential direction, extend by applying a voltage, and return to their original length by releasing the application of the voltage. A plurality of piezoelectric elements,
A plurality of moving bodies supported by the respective piezoelectric elements and moving according to the expansion of the respective piezoelectric elements, and returning to their original positions as the piezoelectric elements return to their original lengths;
A spherical body having a spherical surface, the spherical surface being supported at a plurality of points by the plurality of moving bodies,
A spherical motor in which each moving body supports the spherical body, and the moving direction of the moving body includes a tangential direction component of the spherical body.   The spherical motor according to claim 1, further comprising an elastic pressing member that elastically presses and supports the spherical body from a side opposite to a center of a plurality of points supported by the plurality of moving bodies.   The spherical motor according to claim 1, wherein the moving body is a roller or a sphere.   The spherical motor according to any one of claims 1 to 3, wherein the plurality of moving bodies includes four moving bodies arranged at equal angular intervals in the circumferential direction.   5. The spherical motor according to claim 4, wherein the four moving bodies are arranged on the same plane, or the four moving bodies are arranged on different planes for each opposed pair.   The spherical motor according to claim 1, wherein the plurality of piezoelectric elements are individually driven by a repetitive signal.   The spherical motor according to claim 6, wherein the repetitive signal is a rectangular wave or a sawtooth wave.

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