JP4460365B2 - Bearing and ultrasonic motor - Google Patents

Description

  The present invention relates to a bearing and an ultrasonic motor, and more particularly to a bearing that rotates a shaft using ultrasonic mechanical vibration and an ultrasonic motor in which the bearing is applied to a part of a preload mechanism of a rotor.

  Conventionally, a bearing has been widely used as a component constituting a bearing rotation mechanism of a shaft. In particular, ball bearings in which a plurality of metal balls are arranged for lubrication between the inner ring and the outer ring of the bearing to reduce rotational resistance are slid in the axial direction of a shaft fixed to the inner ring (so-called “axial sliding”). It is used in various fields as an excellent bearing with a mechanism to prevent the above.

  For this reason, the ball bearing is an indispensable component when constructing a preload mechanism of an ultrasonic motor that is often used with a heavy object attached vertically above the shaft. High-accuracy ultrasonic motors that use shafts to prevent shaft slip have been put into practical use one after another.

The details of the configuration and operating principle of the ultrasonic motor are disclosed in Non-Patent Document 1 below, for example.
Kentaro Nakamura, Minoru Kurosawa, Sadayuki Ueha, “Characteristics of a Hybrid Transducer-Type Ultrasonic Motor,” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 38, No. 3, May 1991, pp. 188-193

  However, the ball bearing has a disadvantage that its rotational resistance is extremely increased when an excessive force is applied in the axial direction of the shaft fixed to the inner ring.

Here, the main objects to be solved by the present invention are as follows.
That is, the first object of the present invention is to provide a bearing and an ultrasonic motor capable of generating a rotational torque without increasing the rotational resistance even when an excessive force is applied in the axial direction of the shaft. Is.

  A second object of the present invention is to provide a bearing and an ultrasonic motor that do not cause shaft slip even when an excessive force is applied in the axial direction of the shaft.

  Other objects of the present invention will become apparent from the specification, drawings, and particularly the description of each claim.

  The bearing according to the present invention includes a shaft having a plurality of circumferential ridges projecting in a multistage circumferential manner, and a plurality of circumferential grooves engraved in a multistage circumferential manner according to the form of the plurality of circumferential ridges. Bearing members, pressure contact elastic means for steadily pressing each outer peripheral edge region of the plurality of rotating ridges against each inner peripheral edge region of the corresponding plurality of rotating grooves, and obtaining a steady pressure contact by the pressure contact elastic means And a shaft exciter that excites the shaft by ultrasonic mechanical vibration in a state in which the shaft is provided.

  Further, in the ultrasonic motor of the present invention, the main body of the rotor is configured, the shaft is provided with a plurality of rotating ridges projecting in a multi-stage loop shape, and the multi-stage rotation is performed according to the form of the plurality of rotating ridges. Bearing member comprising a plurality of circumferential grooves engraved in a shape, and a pressure contact elasticity that steadily presses each outer peripheral edge region of the plurality of circumferential protrusions to each inner peripheral edge region of the corresponding plurality of circumferential grooves And a stator that includes a plurality of piezoelectric elements in a multi-layer structure, and in which the shaft is excited by ultrasonic mechanical vibration in a state in which steady pressure welding is obtained by the pressure welding elastic means, and a friction member fixed to the vibration end face of the stator And a vibration receiving member that is integrally provided at the base end of the shaft and forms a part of the rotor and receives ultrasonic mechanical vibration conducted on the friction member. .

  More specifically, in order to solve the problem, the present invention achieves the above-mentioned object by adopting a new characteristic configuration means ranging from the superordinate concept listed below to the subordinate concept. .

That is, the first feature of the bearing of the present invention is that a shaft comprising a plurality of circumferential ridges that occupy a section area along the axial direction and project in a multistage circumferential manner, and the plurality of the plurality of circumferential ridges in the shaft. The shape and number of the plurality of orbiting ridges includes a shaft hole that encloses the entire occupied section area of the orbiting ridge, and the plurality of orbiting ridges are held in a loosely fitted state in the shaft hole. Corresponding to a bearing member comprising a plurality of circumferential grooves carved on the inner surface of the shaft hole in a multi-stage circumferential shape that is slightly larger than the outer shape of each of the circumferential ridges, and the bearing member with respect to the shaft hole While setting the relative position of the penetrating shaft on the same axis, each outer peripheral edge region extending over the plurality of rotating protrusions is changed to each inner peripheral edge region extending over the plurality of rotating grooves corresponding to the plurality of rotating protrusions. Pressure-welded elastic hand for constantly elastically pressure-contacting When, in a state where the yield a steady elastic pressure against a plurality of circumferential grooves of the plurality of orbiting ridges by the pressing elastic means, ultrasonic mechanical vibrations causing rotational torque in a direction to urge the rotation to the shaft It has a, a shaft exciter for exciting the pressing elastic means is stretched over the opposite surfaces of the shaft exciter and the bearing member, said orbiting protrusion has a vertically symmetrical weight surface Both are substantially spindle-shaped with the same size, and are configured such that the virtual vertex of each spindle is located on the central axis of the shaft. None, the bearing is configured such that the virtual vertex of each weight is positioned on the central axis of the shaft hole in the bearing member .

  A second feature of the bearing according to the present invention is that the shaft exciter according to the first feature of the bearing according to the present invention continuously induces flexural vibrations in two directions orthogonal to the shaft by phase difference excitation of 90 degrees. The present invention employs a bearing configuration that excites the shaft by the ultrasonic mechanical vibration that generates the bending vibration mode.

  According to a third feature of the bearing of the present invention, the plurality of rotating ridges in the first or second feature of the bearing of the present invention are provided on a shaft constituting a motor shaft of an arbitrary drive motor, and the shaft The exciter employs a bearing configuration in which the shaft is excited by the ultrasonic mechanical vibration that generates a rotational torque in a direction for energizing the rotation of the shaft during power feeding to the drive motor. .

  According to a fourth aspect of the bearing of the present invention, the shaft exciter according to the third aspect of the bearing of the present invention is a main body of the driving motor so that the shaft of the driving motor is excited by the ultrasonic mechanical vibration. It is in the configuration adoption of the bearing that is fixed to a part of the bearing.

  According to a fifth feature of the bearing of the present invention, the pressure contact elastic means according to the third or fourth feature of the bearing of the present invention spans the facing surface of the bearing member and the drive motor, and surrounds the shaft. Thus, the configuration of the bearing is constituted by a plurality of elastic bodies stretched on the concentric circles at equal intervals in the circumferential direction.

  A sixth feature of the bearing according to the present invention is that the shape of the plurality of rotating ridges in the first, second, third, fourth, or fifth feature of the bearing according to the present invention repeats a mountain shape continuously on the outer periphery. It is in the configuration adoption of the bearing that is a multiple type.

The first feature of the ultrasonic motor of the present invention is that it comprises a rotor main body, and has a plurality of rotating ridges that occupy a section area along the axial direction and project in a multi-stage circular shape. And a shaft hole that encloses the entire occupied section region of the plurality of rotating ridges in the shaft, and the plurality of rotating ridges are held in the loosely fitted state in the shaft hole. A bearing member comprising a plurality of circumferential grooves engraved on the inner surface of the shaft hole in a multi-stage circumferential shape that is slightly larger than the outer shape of each of the circumferential projections and corresponding to the shape and number of the plurality of circumferential projections. And the plurality of peripheral edge regions extending over the plurality of rotating ridges corresponding to the plurality of rotating ridges while coaxially setting the relative position of the shaft penetrating the shaft member with respect to the shaft hole. The elastic pressure is steadily applied to each inner peripheral region over the circumferential groove And pressing the elastic means for, will have a plurality of piezoelectric elements by a multilayer structure, while receiving a constant elastic pressure by the pressing elastic means for said plurality of circumferential grooves of the plurality of orbiting protrusions, said shaft A stator that excites ultrasonic mechanical vibrations that generate rotational torque in the direction of energizing the rotation, a friction member fixed on the vibration end surface of the stator, and a base end of the shaft. constitutes a part of the rotor, have a, a vibration-receiving member for receiving the ultrasonic mechanical vibration that is conducted on the friction member from the oscillation end surface of the stator, the pressure resilient means, said bearing The circumferential ridge is stretched between opposing parts of the member and the stator, and the circular protrusion has a substantially spindle shape having a vertically symmetrical weight surface and the same size, and the virtual vertex of each weight is the shaft. Configured to lie on the central axis The circumferential groove, both without a size equal substantially spindle-shaped having a vertical symmetry weight surface, the ultrasonic motor configured virtual apex of each spindle is positioned on the center axis of the shaft hole in the bearing member It is in configuration adoption.

  According to a second feature of the ultrasonic motor of the present invention, the pressure contact elastic means in the first feature of the ultrasonic motor of the present invention performs the steady elastic pressure contact with the plurality of circumferential grooves of the plurality of circumferential protrusions. At the same time, in order to apply a preload to the shaft, functional means is provided for constantly elastically pressing the vibration receiving member provided on the shaft against the friction member fixed to the stator. Therefore, the configuration of the ultrasonic motor is adopted.

  According to a third feature of the ultrasonic motor of the present invention, the pressure contact elastic means according to the second feature of the ultrasonic motor of the present invention includes a flange member interposed between the bearing member and a vibration node surface of the stator. The ultrasonic motor has a configuration adopting a plurality of elastic bodies that are stretched at equal intervals in a circumferential direction so as to extend between confronting parts and surround the shaft around the center.

  According to a fourth feature of the ultrasonic motor of the present invention, when the pressure contact elastic means in the second or third feature of the present invention ultrasonic motor is in the steady elastic pressure contact with the friction member of the vibration receiving member, The ultrasonic motor is configured to include a translational motion suppressing means for suppressing the translational motion in the direction perpendicular to the axis that can occur in the shaft in accordance with the ultrasonic mechanical vibration on the pressure contact region.

  According to a fifth feature of the ultrasonic motor of the present invention, the translational motion suppressing means according to the fourth feature of the ultrasonic motor of the present invention is between the outer peripheral edge region of the bearing member and the outer peripheral edge region of the flange member. The ultrasonic motor has a configuration adopting a plurality of slide members which are provided in parallel with the shaft and at equal intervals in the circumferential direction and which are configured to be capable of guiding and sliding the bearing member only in the axial direction.

  A sixth feature of the ultrasonic motor of the present invention is that the stator according to the first, second, third, fourth, or fifth feature of the ultrasonic motor of the present invention includes the plurality of piezoelectric elements. It is in the configuration adoption of an ultrasonic motor that constitutes a Langevin type vibrator.

  A seventh feature of the ultrasonic motor of the present invention is that the stator according to the first, second, third, fourth, or fifth feature of the ultrasonic motor of the present invention includes the plurality of piezoelectric elements. The present invention employs a configuration of an ultrasonic motor that constitutes a traveling wave type vibrator.

  As described above, according to the bearing of the present invention, the rotating ridges having the abacus multiplex shape protruding on the shaft of the normal shaft or the driving motor have the corresponding rotating loops in the shaft hole of the bearing member. The shaft is held in a loosely fitted state by the groove, and the shaft rotates by ultrasonic mechanical vibration that generates a flexural vibration mode while obtaining a steady pressure contact with the circular groove of the circular protrusion by means of a pressure elastic means such as an elastic body. Since it is excited to be energized, a rotational torque that cancels an increase in rotational resistance when an excessive force is applied in the axial direction of the shaft is generated in the pressure contact region. A mechanism capable of greatly reducing rotational resistance without causing shaft slip is obtained.

  Further, according to the ultrasonic motor of the present invention, the basic configuration of the bearing is adopted as a part of the preload mechanism, and the specific configuration is a stator such as a Langevin type vibrator or a traveling wave type vibrator, Since it is embodied by means of translational motion suppression means such as a friction member on the stator, a rotor having a vibration receiving member, and a slide member, the same effect as that in the bearing can be obtained in the ultrasonic motor. Become.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a shaft bearing example and a rotational torque generating bearing example will be described as bearing examples, and then an ultrasonic motor example will be described in detail. To do.

(Example of shaft / bearing)
FIGS. 1A to 1C are configuration diagrams of a shaft bearing according to an embodiment of the present invention. FIG. 1A is a front view of a shaft constituting the shaft bearing. b) is an exploded front view of a bearing member constituting the shaft bearing, and FIG. 5C is a partially exploded front view of the entire shaft bearing.

  As shown in the figure, the shaft bearing α according to the present embodiment is basically configured to have a shaft 1 and a bearing member 2, and the shaft 1 is one section along the axial direction thereof. A plurality of (four in this example) circumferential ridges 11, 11,... Occupying a region and projecting in a multistage circumferential manner are provided, and the bearing member 2 has each circumferential ridge 11 on the shaft 1. , 11,..., 11,..., And the circumferential ridges 11, 11 so that the circumferential ridges 11, 11,. ,... Are provided in a plurality of (four in this example) circumferential grooves 22, 22,...

  Note that the illustrated bearing member 2 shows only one of the members divided into two on the plane including the shaft. Actually, after the shaft 1 is enclosed in the shaft hole 21, both divided members are formed on the plane. The entire structure is formed by abutting and firmly fixing them using a fixing means such as a screw (hereinafter the same in each embodiment described later).

  Here, the four rotating ridges 11, 11,... Shown in this example have an abacus multiplex shape in which the same chevron is continuously repeated in the vertical direction of the outer periphery. The spindles have substantially the same spindle shape, and are configured such that the virtual vertex of each spindle is located on the central axis of the shaft 1. Further, the four circumferential grooves 22, 22,... Correspond to the forms of the respective circumferential protrusions 11, 11,... So as to be held in a loosely fitted state in the shaft hole 21. 11 is a substantially spindle shape that is slightly larger than the outer shape of 11,... And has a vertically symmetrical weight surface, and the same size, and the virtual vertex of each weight is also the central axis of the shaft hole 21 in the bearing member 2. Configured to sit on top.

  .. And the circumferential grooves 22, 22,... Are not necessarily arranged adjacent to each other as in this example, and an arbitrary interval is provided along the axial direction of the shaft 1. It may be arranged in a distributed manner. Further, the number of arrangements is also arbitrary, and it is not always necessary to be four as in this example.

  In the shaft bearing α configured as described above, the inventor of the present application defines each outer peripheral edge region extending over the plurality of rotating ridges 11, 11,... Provided in the shaft 1 in the shaft hole 21 of the bearing member 2. The shaft 1 is regarded as a rotor of an ultrasonic motor in a state in which it is constantly pressed against each inner peripheral edge region extending over the corresponding plurality of circumferential grooves 22, 22,. An experiment was conducted to give the same kind of mechanical vibration as the ultrasonic frequency of the ultrasonic motor stator to the rotor. As a result, the ultrasonic mechanical vibration is conducted to the press contact region between each of the rotating ridges 11, 11,... And each of the rotating grooves 22, 22,..., And the shaft 1 rotates by the frictional force of the press contact region. It has been found that torque is produced.

  In the example of the rotational torque generating bearing described below, the required pressure elastic means, the shaft exciter, and the driving motor for obtaining the rotational torque are added to the basic structure of the shaft bearing α described above. In this way, the shaft bearing α is put to practical use.

(Example of rotating torque generating bearing)
FIG. 2 is a partially exploded front view showing the configuration of the rotational torque generating bearing according to the embodiment of the present invention. It should be noted that the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.

  As shown in the figure, the rotational torque generating bearing β according to the present embodiment is a shaft that penetrates the shaft hole 21 of the bearing member 2 as a required pressure contact elastic means in addition to the components of the shaft bearing α described above. While the relative position of 1 is set on the same axis, each outer peripheral edge region extending over the plurality of rotating ridges 11, 11,... Is stationary with respect to each inner peripheral edge region extending over the corresponding plurality of rotating grooves 22, 22,. Are elastically pressed against each other, and a plurality of circumferential grooves 22, 22,... Of the plurality of circumferential ridges 11, 11,. The shaft exciter 4 is configured to excite the shaft 1 by ultrasonic mechanical vibration in a state in which a steady elastic pressure welding is obtained.

  Here, the shaft 1 is a motor shaft that forms a constituent member of an arbitrary drive motor 5, and a plurality of rotating ridges 11, 11,... Are provided on the shaft 1. The shaft exciter 4 functions to excite the shaft 1 by ultrasonic mechanical vibration that generates a rotational torque in a direction for energizing the rotation of the shaft 1 when power is supplied to the driving motor 5. In order to obtain this function, the shaft exciter 4 is fixed to a part of the main body of the driving motor 5 (the back surface in this example) so that the shaft 1 of the driving motor 5 is excited by the ultrasonic mechanical vibration. In order to obtain the required ultrasonic mechanical vibration, for example, a flexural vibration mode is generated in which a flexural vibration in two directions orthogonal to the shaft 1 is continuously induced by phase difference excitation of 90 degrees. .

  On the other hand, the plurality of elastic bodies 3, 3,... Are made of various rubbers having the same elastic coefficient, tension coil springs (springs), etc., and are opposed to the bearing member 2 and the drive motor 5, that is, bearings. The shaft hole 21 of the bearing member 2 spans between the outer peripheral edge region of the shaft receiving surface 2a of the member 2 and the outer peripheral edge region of the shaft standing surface 5a of the drive motor 5 that is installed opposite to the shaft receiving surface 2a. And the shaft 1 of the drive motor 5 are concentrically arranged at equal intervals in the circumferential direction so as to surround the shaft 1 (in the drawing, the tension coil ridge is illustrated, but compression is sometimes performed. Coil struts may be used).

  The shaft 1 of the drive motor 5 and the shaft hole 21 of the bearing member 2 constitute the same axis because the respective weights forming the respective circumferential ridges 11, 11,... And the respective circumferential grooves 22, 22,. This is because the virtual vertices are both located on the central axes of the shaft 1 and the shaft hole 21 (see the description of FIG. 1). Then, the above-described elastic bodies 3, 3,... Having the same elastic coefficient are stretched evenly and equidistantly with the same axis as the center, so that the relative position of the shaft 1 relative to the shaft hole 21 is coaxial. The bearing member 2 is evenly pulled in the direction of the driving motor 5 in the state where the setting is maintained upward, and as a result, each of the rotating ridges 11, 11,. The outer peripheral edge region comes to be in an elastic pressure contact with each inner peripheral edge region over the plurality of circumferential grooves 22, 22,... In the shaft hole 2 (in order to obtain a stable steady elastic pressure contact, a plurality of It is necessary to use at least three elastic bodies 3, 3,..., Preferably about 6-8.

  Further, for example, when the diameter of the drive motor 5 is smaller than that of the shaft exciter 4, a plurality of elastic bodies 3, 3,... Cannot be disposed at a predetermined position of the drive motor 5. However, in this case, the plurality of elastic bodies 3, 3,... May be disposed on the motor fixing surface 4a of the shaft exciter 4 that is exposed to the outside.

  The operation of the rotational torque generating bearing β configured as described above follows the following principle. That is, the ultrasonic mechanical vibration generated from the shaft exciter 4 is first conducted to the shaft 1 through the main body of the driving motor 5 and further, the rotating ridges 11, 11,. 2 reach the pressure contact region with each of the circumferential grooves 22, 22,.

  At this time, an ultrasonic mechanical vibration is generated in the shaft exciter 4 to generate a rotational torque in a direction for energizing the rotation of the shaft 1 when power is supplied to the drive motor 5, and the ultrasonic mechanical vibration is applied to the pressure contact. If it is made to conduct to a region, the shaft 1 itself generates a rotational torque by using a frictional force generated by elastic pressure welding in the region as a driving source, and as a result, the shaft accompanying power supply to the driving motor 5 The rotation resistance of 1 is assisted by the rotation torque, and the rotation resistance is greatly reduced.

  The rotational torque generating bearing β described above is positively suitable for a preload mechanism of an ultrasonic motor. An example of an ultrasonic motor to which the bearing is applied will be described below.

(Example of ultrasonic motor)
FIG. 3 is a partially exploded front view showing the configuration of the ultrasonic motor according to the embodiment of the present invention. It should be noted that the same or equivalent components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals as those shown in FIGS.

  As shown in the figure, the ultrasonic motor γ according to the present embodiment adopts the basic configuration of the rotational torque generating bearing β described above, and the shaft exciter 4 in the rotational torque generating bearing β is connected to the ultrasonic motor. The shaft 1 in the shaft bearing α described above is assigned to the main body of the rotor 7 in the ultrasonic motor γ, and a plurality of elasticities in the rotational torque generating bearing β described above are replaced. The bodies 3, 3,... Are deformed.

  That is, the stator 6 is rotated in a state in which steady elastic pressure contact with the plurality of circumferential grooves 22, 22,... Of the plurality of circumferential protrusions 11, 11,. In order to excite the shaft 1 as the child 7 by ultrasonic mechanical vibration, as a plurality of piezoelectric elements configured in multiple layers, for example, two piezoelectric elements 8 and 8 for flexural vibration in the pitch direction having mutually orthogonal vibration directions, A Langevin type vibrator having two piezoelectric elements 9 and 9 for flexural vibration in the roll direction is used. The Langevin type vibrator allows a 90 degree phase difference between flexural vibrations in two orthogonal directions. A flexural vibration mode that is continuously induced by excitation is generated (see the description of FIG. 2). In addition, instead of the Langevin type vibrator, a traveling wave type vibrator may be employed in some cases.

  Further, a friction member 61 is fixed on the vibration end surface of the stator 6 (on the upper end surface in the figure), and on the vibration node surface (non-vibration surface) in the intermediate region in the longitudinal direction of the stator 6. The flange member 62 is interposed.

  On the other hand, at the base end of the shaft 1 constituting the main body of the rotor 7, a vibration receiving member 12 that receives ultrasonic vibrations transmitted from the vibration end surface of the stator 6 onto the friction member 61 is rotated. The rotor 7 is provided integrally with the shaft 1 so as to constitute a part of the child 7 (that is, the rotor 7 is composed of the shaft 1, a plurality of rotating ridges 11, 11,..., And a vibration receiving member 12).

  On the other hand, the plurality of elastic bodies 3, 3,... Are composed of various rubbers having the same elastic modulus, tensile coil ridges, etc., and the plurality of rotating ridges 11, 11,. At the same time as obtaining a constant elastic pressure contact, a vibration receiving member 12 provided on the shaft 1 is applied to the friction member 61 fixed to the stator 6 in order to apply a preload to the shaft 1 constituting the rotor 7. Between the opposing portions of the bearing member 2 and the flange member 62 layered on the vibration node surface of the stator 6, that is, the shaft of the bearing member 2, so that the functional means for constantly elastically pressing against the bearing is provided. Between the outer peripheral edge region of the receiving surface 2a and the outer peripheral edge region of the bearing facing surface 6a of the flange member 62 installed opposite to the shaft receiving surface 2a, the shaft hole 21 of the bearing member 2 and the stator 6 Coaxial on both sides Is tensioned concentrically in the circumferential direction at equal intervals equiangularly equidistant shaped so as to surround the shaft 1 as the center.

  It is to be noted that the pressure contact elastic means comprising a plurality of elastic bodies 3, 3,... Is provided with the ultrasonic vibration of the rotor 7 in accordance with the ultrasonic mechanical vibration on the pressure contact area at the time of steady elastic pressure contact with the friction member 61 of the vibration receiving member 12. As a translational motion restraining means for restraining the translational motion in the direction perpendicular to the axis that can occur in the shaft 1, the shaft is centered on the same axis between the outer peripheral edge region of the bearing member 2 and the outer peripheral edge region of the flange member 62. 1 and a plurality of slide members 10, 10,... Which are arranged in parallel with the circumferential direction and at equal intervals in the circumferential direction and configured to be capable of guiding and sliding the bearing member 2 only in the axial direction. The shaft hole 21 of the bearing member 2 and the stator 6 are coaxial. (To obtain a stable translational motion prevention function, there are at least three slide members 10, 10,. It is necessary to use about 8 That).

  The operation of the ultrasonic motor γ configured as described above follows the following principle. That is, ultrasonic mechanical vibration generated from the piezoelectric elements 8 and 8 for flexural vibration of the stator 6 in the pitch direction and the piezoelectric elements 9 and 9 for flexural vibration of the roll direction is first generated by the friction member 61 and the vibration receiving member of the rotor 7. .. Are transmitted to the shaft 1 through 12, and reach the pressure contact region between the rotating ridges 11, 11,... On the shaft 1 and the rotating grooves 22, 22,.

  At this time, the stator 6 is caused to generate an ultrasonic mechanical vibration that generates a rotational torque in a direction for energizing the rotation of the rotor 7 when the ultrasonic motor γ is driven, and the ultrasonic mechanical vibration is generated in the pressure contact region. If the shaft 1 is made to conduct, the shaft 1 itself generates a rotational torque using the frictional force generated by the elastic pressure contact in the region as a drive source. As a result, the shaft 1 accompanying the driving of the ultrasonic motor γ The rotation is assisted by the rotation torque, and the rotation resistance is greatly reduced.

  And the total rotational torque of the ultrasonic motor γ adopting the above configuration has been confirmed by the inventor's actual measurement to be nearly doubled compared to the case of using the preload mechanism by the conventional ball bearing. It was done.

  Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described means, and can be appropriately modified within the scope of the above-described effects. is there.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the shaft bearing which concerns on one Embodiment of this invention, (a) is a front view of the shaft which comprises the shaft bearing, (b) is an exploded view of the bearing member which comprises the shaft bearing Front view, (c) is a partially exploded front view of the entire shaft bearing. It is a partially exploded front view which shows the structure of the rotational torque generation bearing which concerns on one Embodiment of this invention. 1 is a partially exploded front view showing a configuration of an ultrasonic motor according to an embodiment of the present invention.

Explanation of symbols

[alpha] ... shaft bearing [beta] ... rotational torque generating bearing [gamma] ... ultrasonic motor 1 ... shaft 11 ... (several) orbits 12 ... vibration receiving member 2 ... bearing member 2a ... shaft receiving surface 21 ... shaft hole 22 ... (several) 1) Circumferential groove 3 ... Elastic body 4 ... Shaft exciter 4a ... Motor fixing surface 5 ... Drive motor 5a ... Shaft standing surface 6 ... Stator 6a ... Bearing facing surface 61 ... Friction member 62 ... Flange Member 7... Rotor 8... (Two) piezoelectric elements for flexural vibration in the pitch direction 9... (Two) piezoelectric elements for flexural vibration in the roll direction 10..

Claims (13)

A shaft comprising a plurality of circumferential ridges that occupy one section region along the axial direction and project in a multistage circumferential manner;
The shaft includes a shaft hole including the entire occupied section region of the plurality of rotating ridges on the shaft, and the plurality of rotating ridges are held in the loosely fitted state in the shaft hole. A bearing member comprising a plurality of circumferential grooves engraved on the inner surface of the shaft hole in a multi-stage circumferential shape that is slightly larger than the outer shape of each of the circumferential ridges corresponding to the shape and number of the ridges, and
While setting the relative position of the shaft penetrated with respect to the shaft hole of the bearing member to be coaxial, the outer peripheral edge regions extending over the plurality of rotating ridges are set to the plurality of rotating limbs corresponding to the plurality of rotating ridges. A pressure contact elastic means for making a constant elastic pressure contact with each inner peripheral edge region extending over the groove;
Exciting ultrasonic mechanical vibrations that generate rotational torque in the direction in which the shaft is urged to rotate in a state in which steady elastic pressure contact with the plurality of circular grooves of the plurality of circular protrusions is obtained by the pressure elastic means. and the shaft exciter that, the possess,
The pressure contact elastic means is stretched across the opposing surface of the bearing member and the shaft exciter,
The orbiting ridge has a substantially spindle shape having a vertically symmetrical weight surface and the same size, and is configured such that the virtual vertex of each weight is located on the central axis of the shaft,
The circumferential groove has a substantially spindle shape having a vertically symmetrical weight surface and the same size, and is configured such that a virtual vertex of each weight is positioned on a central axis of the shaft hole in the bearing member. Bearing. The shaft exciter is
The shaft is excited by the ultrasonic mechanical vibration that generates a bending vibration mode in which bending vibration in two directions orthogonal to the shaft is continuously induced by phase difference excitation of 90 degrees.
The bearing according to claim 1. The plurality of rotating ridges are:
Provided on the shaft constituting the motor shaft of any drive motor,
The shaft exciter is
The shaft is excited by the ultrasonic mechanical vibration that generates a rotational torque in a direction for energizing the rotation of the shaft during power feeding to the drive motor.
The bearing according to claim 1 or 2, wherein The shaft exciter is
The shaft of the driving motor is fixed to a part of the main body of the driving motor so as to be excited by the ultrasonic mechanical vibration.
The bearing according to claim 3. The pressure contact elastic means is
Consists of a plurality of elastic bodies stretched at equal intervals in a circumferential direction on concentric circles so as to surround the shaft around the opposing surface of the bearing member and the drive motor.
The bearing according to claim 3 or 4, characterized by the above. The shape of the plurality of rotating ridges is as follows:
It presents an abacus multiplex shape that repeats chevron on the outer periphery.
The bearing according to claim 1, 2, 3, 4 or 5. A shaft comprising a plurality of orbiting ridges constituting a main body of the rotor and occupying one section region along the axial direction and projecting in a multi-stage orbit;
The shaft includes a shaft hole including the entire occupied section region of the plurality of rotating ridges on the shaft, and the plurality of rotating ridges are held in the loosely fitted state in the shaft hole. A bearing member comprising a plurality of circumferential grooves engraved on the inner surface of the shaft hole in a multi-stage circumferential shape that is slightly larger than the outer shape of each of the circumferential ridges corresponding to the shape and number of the ridges, and
While setting the relative position of the shaft penetrated with respect to the shaft hole of the bearing member to be coaxial, the outer peripheral edge regions extending over the plurality of rotating ridges are set to the plurality of rotating limbs corresponding to the plurality of rotating ridges. A pressure contact elastic means for making a constant elastic pressure contact with each inner peripheral edge region extending over the groove;
A plurality of piezoelectric elements are formed in a multi-layer structure, and in a state in which steady elastic pressure contact with respect to the plurality of circumferential grooves of the plurality of circumferential protrusions is obtained by the pressure contact elastic means, in a direction in which rotation is applied to the shaft A stator that excites ultrasonic mechanical vibrations that produce rotational torque ;
A friction member fixed on the vibration end face of the stator;
A vibration receiving member that is integrally provided at a base end of the shaft and constitutes a part of the rotor, and that receives ultrasonic mechanical vibration transmitted from the vibration end surface of the stator onto the friction member; Yes, and
The pressure contact elastic means is stretched between opposing portions of the bearing member and the stator,
The orbiting ridge has a substantially spindle shape having a vertically symmetrical weight surface and the same size, and is configured such that the virtual vertex of each weight is located on the central axis of the shaft,
The circumferential groove has a substantially spindle shape having a vertically symmetrical weight surface and the same size, and is configured such that a virtual vertex of each weight is positioned on a central axis of the shaft hole in the bearing member. Ultrasonic motor. The pressure contact elastic means is
The vibration receiving member provided on the shaft is fixed to the stator so as to apply a preload to the shaft at the same time as obtaining the steady elastic pressure contact with the plurality of rotating grooves of the plurality of rotating ridges. A functional means for constantly elastically pressing the friction member
The ultrasonic motor according to claim 7. The pressure contact elastic means is
A plurality of elastic bodies extending between confronting portions of the bearing member and the flange member interposed between the vibration node surfaces of the stator and concentrically around the shaft so as to surround the shaft. Consist of,
The ultrasonic motor according to claim 8. The pressure contact elastic means is
Translational motion suppression for restraining translational motion in a direction perpendicular to the axis that can occur in the shaft in accordance with the ultrasonic mechanical vibration on the pressure contact region during the steady elastic pressure welding of the vibration receiving member to the friction member. Have both means,
The ultrasonic motor according to claim 8 or 9, characterized in that. The translational movement inhibiting means is
Between the outer peripheral edge area of the bearing member and the outer peripheral edge area of the flange member, it is provided in parallel with the shaft and at equal intervals in the circumferential direction, and the bearing member is configured to be slidable only in the axial direction. Consisting of a plurality of slide members,
The ultrasonic motor according to claim 10. The stator is
A Langevin type vibrator is constituted by the plurality of piezoelectric elements.
The ultrasonic motor according to claim 7, 8, 9, 10, or 11. The stator is
A traveling wave type vibrator is constituted by the plurality of piezoelectric elements.
The ultrasonic motor according to claim 7, 8, 9, 10, or 11.

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