JP3437781B2 - Ultrasonic motor and steering device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for supporting a rotary shaft of an ultrasonic motor and a steering device that tilts, for example, a steering column using the ultrasonic motor as a drive source.

[0002]

2. Description of the Related Art In recent years, an ultrasonic motor has been used as a drive source for various actuators mounted on a vehicle, for example, a drive source for an actuator that tilts a steering column.

FIG. 14 shows a conventional steering device 50 having a tilt mechanism. The steering column 53 is supported by a fixed bracket 52 fixed to a part of the vehicle body 51 so as to be vertically rotatable (tilted) by a rotating shaft 54. The fixed bracket 52 and the steering column 53 have a substantially cylindrical shape, and a steering shaft 55 that is bendable as the column 53 tilts is inserted and rotatably supported. A steering wheel 56 is fixed to a steering shaft 55 protruding from the upper end of the steering column 53. The steering wheel 56 can be tilted together with the steering column 53 with respect to the fixed bracket 52.

A pair of mounting pieces 53a is provided on the lower surface side of the steering column 53, and the ultrasonic motor 1 for tilt driving is supported by the mounting pieces 53a so as to be vertically rotatable. The rotary shaft 6 of the ultrasonic motor 1 is integrally formed with a worm portion 6a having a thread groove formed on the outer peripheral surface thereof.

On the other hand, a pair of mounting pieces 52a is provided on the lower surface side of the fixed bracket 52, and a nut member 57 is supported on the mounting piece 52a so as to be vertically tiltable. Nut member 5
7 is screwed with the worm portion 6a of the rotary shaft 6 extending from the ultrasonic motor 1. When the rotary shaft 6 rotates forward and backward by the operation of the ultrasonic motor 1, the steering column 53 (steering wheel 56) tilts in the vertical direction by the worm portion 6a and the nut member 57. In this way, the position of the steering wheel 56 is adjusted by the operation of the ultrasonic motor 1.

FIG. 11 shows a sectional view of the ultrasonic motor 1. The housing 2 of the ultrasonic motor 1 is composed of a base 3 and a cover 4. The outer race 5a of the ball bearing 5 is fixed to the base 3. The inner race 5b of the ball bearing 5 is fixed to the rotary shaft 6. A slide bearing 7 is fixed to the cover 4. The rotary shaft 6 includes the worm portion 6a and is rotatably supported by the ball bearing 5 and the slide bearing 7 with respect to the housing 2.

A stator 8 is fixed to the base 3 with screws 9. A rotor 13 to be described later is provided on the outer peripheral portion of the stator 8.
A vibration transmission portion 8a is formed to transmit the vibration to. The base ring 10 is fixed to the lower surface of the outer peripheral portion of the stator 8 in the vibration transmitting portion 8a, and the piezoelectric element 11 is fixed to the lower surface of the base ring 10.

On the upper surface of the stator 8, a rotor 13 provided with a lining material 12 that abuts against the vibration transmitting portion 8a.
Is provided. The rotor 13 is coupled to the rotating shaft 6 so as to be movable in the axial direction and not relatively rotatable. Rotor 1
The upper surface of 3 is pressed by a pressure urging member 16 including a disc spring 14 and a plate 15. That is, in a state where the disc spring 14 is elastically deformed, the plate 15 is connected to the rotation shaft 6 so as not to rotate and further circlip 17 so as not to move upward in FIG. In this manner, the elastic force of the disc spring 14 causes the rotor 13 to be pressed against the stator 8 with a predetermined pressing force. Incidentally, in this embodiment, the pressure contact force of the rotor 13 with respect to the stator 8 is 2
It is set to 8 [kgf].

At this time, the rotating shaft 6 is moved upward (in the direction of arrow A in FIG. 11) by the elastic force of the disc spring 14.
It is urged with an urging force of 8 [kgf]. Therefore, FIG.
As shown in detail in (a), since the outer race 5a and the inner race 5b are relatively slightly deviated from each other due to the nature of the ball bearing 5, the rotary shaft 6 is located at the upper end position.

In the ultrasonic motor 1 configured as described above, when a high frequency drive voltage is applied to the piezoelectric element 11, the piezoelectric element 11 vibrates, and the vibration of the piezoelectric element 11 passes through the base ring 10 to the stator 8. It is converted into traveling wave vibration in the vibration transmitting portion 8a. Then, the rotor 13 rotates based on this traveling wave vibration, and the rotating shaft 6 rotates. Such rotation of the rotary shaft 6 is utilized for the tilt operation of the steering column 53 described above.

[0011]

However, an external force is applied to the steering column 53 due to the vibration of the vehicle, the load of the driver, or the like. At this time, a large load (in this case, a reaction force generated by the nut member 57) is applied to the rotary shaft 6 of the motor 1 that tilts the column 53.

When the load is applied to the rotary shaft 6 in this manner, particularly when the steering wheel 56 is lowered and the load (reaction force) is applied in the direction of arrow B in FIGS. 11 and 14, the load is directly applied to the disc spring 14. This causes the disc spring 14 to be further elastically deformed. Then, the pressure contact force of the rotor 13 with respect to the stator 8 changes, and the rotation characteristics of the rotor 13 change. For this reason, the tilting operation of the steering column 53 does not operate smoothly, which may cause a driver discomfort.

Further, as shown in FIG. 13, the rotary shaft 6
When the load applied to the outer race 5a exceeds the elastic force of the disc spring 14 (pressure contact force of the rotor 13), that is, when the load exceeds 28 [kgf], the outer race 5a and the inner race 5b are relatively opposed to each other as shown in FIG. 12 (b). And the rotary shaft 6 is displaced to the lower end position (the backlash displacement amount is the maximum value lmax). That is, the displacement of the rotary shaft 6 causes the steering column 53 to rattle, which may cause the driver to feel uncomfortable as in the above case.

The present invention has been made to solve the above problems, and a first object of the present invention is to change the rotational characteristics of a rotor due to an axial load applied to a rotating shaft and the rotating shaft due to the same load. An object of the present invention is to provide an ultrasonic motor capable of suppressing rattling.

A second object of the present invention is to provide a steering device using an ultrasonic motor as a drive source, which can suppress discomfort to the driver.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 is connected to a rotating shaft rotatably supported by a housing, with respect to a stator having a piezoelectric element attached thereto. In the ultrasonic motor for rotating the rotating shaft by rotating the rotor by pressing the rotor based on the urging force of the pressure urging member engaging with the rotating shaft, the rotor is rotated based on the driving of the piezoelectric element. A shaft biasing member that biases the rotary shaft in the same direction as the direction in which the rotary shaft is biased by the biasing force of the pressure biasing member, and absorbs a load applied to the rotary shaft in a direction opposite to the direction. Equipped with.

According to a second aspect of the present invention, in the ultrasonic motor according to the first aspect, the rotary shaft is formed with an accommodating recess extending in the axial direction and accommodating the shaft biasing member. According to a third aspect of the present invention, in the ultrasonic motor according to the second aspect, the shaft urging member includes an elastic member that applies an urging force to the rotating shaft, and a regulating member that elastically deforms the elastic member. And a plate fixed to the housing in a state in which the elastic member is elastically deformed by coming into contact with the restriction member.

According to a fourth aspect of the present invention, a fixed bracket is provided with a drive source for rotating a rotary shaft having a worm portion, the steering column being supported by a fixed bracket fixed to a vehicle body so as to be tiltable in the vertical direction. Alternatively, a nut member that is attached to either side of the steering column and that is screwed into the worm portion in order to convert the rotational movement of the rotary shaft into a reciprocating linear movement is attached to the other side, and the steering is driven by the drive source. A steering device for tilting a column with respect to a fixed bracket, wherein the drive source includes a rotor connected to a rotation shaft rotatably supported by a housing with respect to a stator having a piezoelectric element mounted thereon. Is pressed against the urging force of the pressure urging member engaging with
An ultrasonic motor that rotates a rotor based on driving of the piezoelectric element to rotate a rotating shaft, the rotating motor rotating in the same direction as the direction in which the rotating shaft is biased by the biasing force of the pressure biasing member. A shaft urging member for urging the shaft and absorbing a load applied to the rotation shaft in a direction opposite to the above direction is provided.

According to a fifth aspect of the present invention, in the steering device according to the fourth aspect, the shaft urging member is integrally assembled with the ultrasonic motor. According to a sixth aspect of the present invention, in the steering device according to the fourth aspect, the shaft biasing member is interposed between the nut member and the housing of the ultrasonic motor.

According to a seventh aspect of the present invention, in the steering device according to the fourth aspect, the shaft urging member is interposed between the fixed bracket and the steering column.

According to an eighth aspect of the present invention, there is provided a steering column which is supported so as to be vertically tiltable with respect to a fixed bracket fixed to the vehicle body, and a drive source for rotating a rotary shaft having a worm portion is fixed bracket. Alternatively, a nut member that is attached to either side of the steering column and that is screwed into the worm portion in order to convert the rotational movement of the rotary shaft into a reciprocating linear movement is attached to the other side, and the steering is driven by the drive source. A steering device for tilting a column with respect to a fixed bracket, wherein the drive source includes a rotor connected to a rotation shaft rotatably supported by a housing with respect to a stator having a piezoelectric element mounted thereon. Is pressed against the urging force of the pressure urging member engaging with
An ultrasonic motor that rotates a rotor based on driving of the piezoelectric element and rotates a rotating shaft, wherein a direction of a load that acts on the rotating shaft by the weight of the tilting member and a pressure urging member. The ultrasonic motor is arranged so that the direction in which the rotating shaft is biased by the biasing force is the same direction.

Therefore, according to the invention of claim 1,
The shaft urging member urges the rotation shaft in the same direction as the direction in which the rotation shaft is urged by the urging force of the pressure urging member that presses the rotor against the stator. It absorbs the load applied in the opposite direction. Therefore, even if a load is applied to the rotating shaft in the same direction as the pressing biasing member presses the rotor onto the stator, the shaft biasing member absorbs the load, so that the pressing force of the rotor against the stator is reduced. Does not change significantly. As a result, changes in the rotation characteristics of the rotor can be suppressed. Moreover, when the load applied to the rotating shaft exceeds the urging force obtained by adding the urging force of the pressure urging member and the urging force of the shaft urging member, the rotating shaft rattles. Therefore, the load of rattling of the rotating shaft is increased, and the frequency of rattling is drastically reduced. As a result, rattling of the rotating shaft can be suppressed.

According to the second aspect of the present invention, the rotary shaft is provided with a housing recess extending in the axial direction and housing the shaft biasing member. Therefore, the shaft biasing member is housed in the housing recess, so that it is possible to prevent the motor from becoming large in the axial direction.

According to the third aspect of the present invention, the shaft urging member is provided with the elastic member for applying the urging force to the rotating shaft and the regulating member for elastically deforming the elastic member. And
The plate is fixed to the housing in a state in which the elastic member is elastically deformed by abutting the regulating member. Therefore, the elastic member that constitutes the shaft urging member and the regulating member can be easily assembled to the motor by the plate.

According to the fourth aspect of the present invention, the shaft urging member is arranged in the same direction as the direction in which the rotating shaft is urged by the urging force of the pressure urging member for pressing the rotor against the stator. To absorb the load applied to the rotation shaft in the direction opposite to the above direction. Therefore, even if a load is applied to the rotating shaft in the same direction as the pressing biasing member presses the rotor onto the stator, the shaft biasing member absorbs the load, so that the pressing force of the rotor against the stator is reduced. Does not change significantly. As a result, changes in the rotation characteristics of the rotor can be suppressed, and the tilting operation of the steering column can be operated smoothly. Moreover, when the load applied to the rotating shaft exceeds the urging force obtained by adding the urging force of the pressure urging member and the urging force of the shaft urging member, the rotating shaft rattles. Therefore, the load of rattling of the rotating shaft is increased, and the frequency of rattling is drastically reduced. As a result, rattling of the rotary shaft can be suppressed, and rattling of the steering column can be suppressed. As a result, it is possible to prevent the driver from feeling uncomfortable.

According to the fifth aspect of the invention, the shaft urging member is integrally assembled with the ultrasonic motor, so that the assembling work of the steering device can be simplified.
According to the invention of claim 6, the shaft urging member is interposed between the nut member and the housing of the ultrasonic motor, so that the shaft urging member can be retrofitted to the steering device.

According to the seventh aspect of the invention, since the shaft urging member is interposed between the fixed bracket and the steering column, the shaft urging member can be retrofitted to the steering device.

According to the eighth aspect of the invention, in the ultrasonic motor, the rotating shaft is rotated by the direction of the load acting on the rotating shaft by the own weight of the tilting member such as the steering column and the urging force of the pressure urging member. The steering device is installed so that the direction in which the force is applied is the same direction.
With this configuration, the load that changes the pressure contact force of the rotor against the stator against the urging force of the pressure urging member and the load that rattles the rotating shaft are reduced. Therefore, by simply arranging the orientation of the ultrasonic motor appropriately without requiring extra parts, the change in the rotation characteristics of the rotor due to the axial load applied to the rotary shaft of the motor and the rotation shaft due to the same load The rattling can be suppressed together.
As a result, the driver's discomfort can be suppressed.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. For convenience of explanation, the same components as those in the conventional example shown in FIGS. 11 to 14 are designated by the same reference numerals, and the description thereof is partially omitted.

FIG. 1 shows an ultrasonic motor 20 according to this embodiment.
FIG. The ultrasonic motor 20 is provided in the steering device 50a of the vehicle shown in FIG. 5, and is used as a drive source of an actuator that tilts the steering column 53. The ultrasonic motor 20 of this embodiment is characterized by the support structure of the rotating shaft.

More specifically, the inner race 5b of the ball bearing 5 is fixed to the rotary shaft 21, and the rotary shaft 21 is rotatably supported with respect to the housing 2 by the ball bearing 5 and the slide bearing 7. Further, as shown in FIG. 5, the rotary shaft 21 is provided with a worm portion 21a that is screwed into the nut member 57.

An accommodating recess 21a having a circular horizontal cross section is formed in the lower part of the rotary shaft 21 and extends axially from the lower end thereof. As shown in FIGS. 1 to 3, a shaft biasing member 25 including a coil spring 22, a collar 23, and a thrust tip 24 is housed in the housing recess 21a. Incidentally, in this embodiment, the coil spring 22 and the collar 23 are made of iron, and the thrust tip 24 is made of polyimide resin.

The coil spring 22 is formed to have a diameter that substantially abuts the inner peripheral surface of the accommodation recess 21a. The collar 23 is formed in a disk shape with an area substantially the same as the opening area of the accommodation recess 21a, and is inserted after the coil spring 22 is inserted into the accommodation recess 21a. Further, the collar 23 is formed with a circular mounting hole 23a extending in the axial direction. The thrust tip 24 is
It is configured by connecting a quadrangular prism-shaped connecting convex portion 24a extending in the axial direction and a disc-shaped sliding contact portion 24b. The thrust tip 24 is press-fitted into the mounting hole 23 a of the collar 23 at the connecting convex portion 24 a, and is fixed to the collar 23.

A plate 26 covering the bottom of the base 3 (the opening of the housing recess 21a of the rotary shaft 21) is fixed by a screw 27. Incidentally, in this form, the plate 26 is made of iron. The plate 26 is in contact with the sliding contact portion 24b of the thrust tip 24.

The plate 26 is fixed to the base 3 in a state where it abuts the sliding contact portion 24b of the thrust tip 24 and elastically deforms the coil spring 22. Then, the elastically deformed coil spring 22 biases the rotating shaft 21 upward (in the direction of arrow A in FIG. 1). By the way, in this form,
The biasing force of the coil spring 22 is set to 15 [kgf].

Further, since a frictional force acts between the coil spring 22 and the bottom surface 21b of the housing recess 21a and between the coil spring 22 and the collar 23, the shaft urging member 25 causes the rotary shaft 2 to rotate.
Rotate with 1. Therefore, as shown in FIG. 2, grease 28 for reducing the frictional force is applied between the sliding contact portion 24b of the thrust tip 24 and the plate 26. Incidentally, in this form, the grease 28 is a mixture of lithium soap and mineral oil.

A rotor 13, which is in pressure contact with the stator 8, is connected to the rotary shaft 21 so as to be axially movable and relatively non-rotatable. The rotor 13 is pressed against the stator 8 with a predetermined pressing force by the elastic force of the disc spring 14. By the way,
In this embodiment, the pressure contact force of the rotor 13 with respect to the stator 8 is set to 28 [kgf] as in the conventional case.

At this time, the rotary shaft 21 has the disc spring 14
Of the coil spring 22 and the elastic force of the coil spring 22 (see FIG.
43 [kgf] (= 28 [kg
f] +15 [kgf]).

In the ultrasonic motor 20 configured as described above, when a high frequency drive voltage is applied to the piezoelectric element 11 as in the conventional case, the rotor 13 rotates and the rotary shaft 21 rotates,
The tilt operation of the steering column 53 is performed.

Further, a load (in this case, a reaction force generated by the nut member 57) is applied to the rotary shaft 21 by an external force acting on the steering column 53, and in particular, the steering wheel 56 is lowered and the like in FIGS. When a load (reaction force) is applied in the direction of the arrow, the coil spring 22 generates an urging force (repulsion force) corresponding to the load. Therefore, it is necessary to deal with whether the load is fluctuating or steady. You can

Therefore, the load applied to the rotary shaft 21 is 15
Up to [kgf], the load hardly acts on the disc spring 14, and the pressure contact force of the rotor 13 with respect to the stator 8 is maintained at about 28 [kgf]. As a result, the load is 15
Up to [kgf], the rotation characteristics of the rotor 13 hardly change.

Further, as shown in FIG. 4, the rotary shaft 21
When the load applied to the rotating shaft 2 exceeds the biasing force (43 [kgf]) generated by the disc spring 14 and the coil spring 22,
A rattling of 1 (the maximum amount of backlash displacement is lmax) occurs. Therefore, in this embodiment, the rattling load of the rotary shaft 21 is higher than that of the conventional example, and the frequency of rattling is drastically reduced. That is, in the present embodiment, rattling of the rotary shaft 21 is suppressed.

As described above, in this embodiment, the following operational effects can be obtained. (1) A shaft biasing member 25 including a coil spring 22, a collar 23, and a thrust tip 24 is housed in the housing recess 21 a formed in the rotary shaft 21. This coil spring 2
2, the rotary shaft 21 is upward (in the direction of arrow A in FIG. 1),
That is, the disc spring 14 urges the rotating shaft 21 in the same direction as the urging direction. Therefore, when a load is applied to the rotary shaft 21 in the direction of the arrow B in FIG. 1 (direction opposite to the biasing direction), the coil spring 22 substantially absorbs the load up to 15 [kgf]. Therefore, the pressure contact force of the rotor 13 with respect to the stator 8 is maintained at approximately 28 [kgf]. As a result, when the load is up to 15 [kgf], the rotor 1
It is possible to suppress the change in the rotation characteristic of No. 3 above.

(2) Further, the load applied to the rotary shaft 21 is urged by the disc spring 14 and the coil spring 22 (43).
If [kgf]) is exceeded, the rotary shaft 21 will rattle. Therefore, in this embodiment, the rattling load of the rotary shaft 21 is higher than that of the conventional example, and the frequency of rattling is drastically reduced. As a result, rattling of the rotary shaft 21 can be suppressed.

(3) Further, the shaft urging member 25 is the rotary shaft 21.
Since it is accommodated in the accommodating concave portion 21a formed in, it is possible to prevent the ultrasonic motor 20 from becoming large in the axial direction. (4) Moreover, the accommodation recess 21a can restrict the radial movement of the shaft biasing member 25, particularly the coil spring 22.

(5) The plate 26 is the thrust chip 2
The coil spring 22 is elastically deformed by being brought into contact with the sliding contact portion 24b of No. 4 and is fixed to the base 3 by the screw 27. Therefore, the coil spring 22, the collar 23, and the thrust tip 24, which form the shaft biasing member 25 by the plate 26, can be easily assembled to the ultrasonic motor 20.

(6) In this embodiment, since the coil spring 22 is used as the shaft urging member 25, the shaft urging member 25 can be simply constructed. (7) Since the shaft urging member 25 is integrally assembled with the ultrasonic motor 20, the assembling work of the steering device 50a can be simplified.

The above-described embodiment may be modified as follows. In the above-described embodiment, the biasing force generated by the disc spring 14 is set to 28 [kgf] and the biasing force generated by the coil spring 22 is set to 15 [kgf], but the present invention is not limited to this value. .

In the above embodiment, the shaft biasing member 25 is replaced by the coil spring 22, the collar 23, and the thrust tip 24.
However, the structure is not limited to this as long as the rotary shaft 21 can be biased in the same direction as in the above-described embodiment. For example, the coil spring 22 may be changed to an elastic member other than the coil spring 22. Further, although the collar 23 and the thrust tip 24 are separate bodies, they may be integrated.

In the above-described embodiment, as shown in FIG. 1, the rotary shaft 21 is provided with the storage concave portion 21a having a circular horizontal cross section extending in the axial direction from the lower end of the rotary shaft 21 as shown in FIG. Is not limited to this. Further, the accommodation recess 21a may not be particularly formed.

In the above embodiment, the coil spring 22,
The collar 23 and the plate 26 are made of iron, the thrust tip 24 is made of a polyimide resin, and the grease 28 is a mixture of lithium soap and mineral oil, but the material is not limited to this.

In the above embodiment, the coil spring 22, the collar 23 and the thrust tip 2 are arranged in this order as shown in FIG.
Although 4 is arranged, these arrangements may be arranged upside down in FIG. In this case, one end of the coil spring 22 abuts on the plate 26, and the thrust tip 24 is held in the accommodation recess 2
The bottom surface 21b of 1a is brought into contact (sliding contact).

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIGS. 6 and 7. For convenience of explanation, the same components as those in the conventional example shown in FIGS. 11 to 14 are designated by the same reference numerals, and the description thereof is partially omitted.

As shown in FIGS. 6 and 7, in the steering device 50b of this embodiment, the coil spring 30 is interposed between the housing 2 (cover 4) of the ultrasonic motor 1 and the nut member 57 in a state of elastic deformation. To be done. Coil spring 3
The rotary shaft 6 of the motor 1 is inserted through 0. Then, the steering column 53 is biased so as to always tilt upward with respect to the fixed bracket 52. That is,
The coil spring 30 acts in the same manner as the coil spring 22 used in the first embodiment, and cooperates with the disc spring 14 to rotate the rotary shaft 6
Is urged in the direction of arrow A in FIG.

Therefore, a load (in this case, a reaction force generated by the nut member 57) is applied to the rotary shaft 6 by an external force acting on the steering column 53, and in particular, by lowering the steering wheel 56 or the like, in FIGS. Even if a load is applied in the direction of the arrow, the coil spring 30 generates an urging force (repulsive force) in response to the load, so that it is possible to handle the load whether it is fluctuating or steady.

Therefore, also in this embodiment, the rotary shaft 6
It is possible to suppress both the change in the rotation characteristics of the rotor 13 due to the axial load applied to and the rattling of the rotary shaft 6 due to the same load. Moreover, the coil spring 30 can be easily attached to the steering device 50b by retrofitting. Further, the conventional ultrasonic motor 1 can be used without changing.

As shown in FIG. 8, the fixing bracket 5
2 and the upper surface side of the steering column 53, the coil spring 31 is interposed between both members, and
The contraction force of is used. Then, the steering column 53
Is urged so as to always tilt upward with respect to the fixed bracket 52. That is, the rotating shaft 6 is biased in the direction of arrow A by the coil spring 31. Even with such a steering device 50c, it is possible to obtain the same effects as the above. Further, in this case, it may be between the vehicle body 51 and the steering column 53.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to FIGS. 9 and 10. For convenience of explanation, the same components as those in the conventional example shown in FIGS. 11 to 14 are designated by the same reference numerals, and the description thereof is partially omitted.

As shown in FIGS. 9 and 10, in the steering device 50d of this embodiment, the ultrasonic motor 40 is used.
A worm portion 41a is formed on the rotary shaft 41 at the end opposite to the conventional example shown in FIGS. Therefore, in the present embodiment, the disc spring 14 has the rotating shaft 41 shown in FIG.
At 0, it is urged in the direction of arrow B.

With this arrangement, contrary to the conventional example, when a load (reaction force generated by the nut member 57 in this case) is applied to the rotary shaft 41 in the direction of arrow A by lifting the steering wheel 56, the load is applied. Adversely affects the biasing force of the disc spring 14. Then, similarly to the conventional example, the pressure contact force of the rotor 13 with respect to the stator 8 changes, the rotation characteristic of the rotor 13 changes, or the load exceeds the elastic force of the disc spring 14 and the rotating shaft 41 rattles.

However, in the present embodiment, the load (reaction force generated by the nut member 57) acting on the rotary shaft 41 due to the weight of the tilting member such as the steering column 53 and the steering wheel 56 as the fulcrum is applied to the rotary shaft 41. The direction is the same as the direction in which the disc spring 14 biases the rotating shaft 41 (the direction of arrow B). In other words, in the present embodiment, the load (reaction force) in the direction of the arrow A that causes a problem such as rattling does not include the reaction force generated by the own weight of the tilting member, so It is difficult to apply an excessive load (reaction force) in the direction of arrow A.

In other words, in the conventional example shown in FIGS. 11 and 14, the reaction force generated by the weight of the tilting member causes the disc spring 14 to urge the rotating shaft 41 (see FIGS. 11 and 1).
4 in the direction of arrow A) and the opposite direction (in the direction of arrow B in FIGS. 11 and 14), a load in the direction of arrow B in which a problem such as rattling occurs in the conventional example is due to its own weight. The reaction force will be included. Therefore, in the conventional example, an excessive load is likely to be applied to the rotating shaft 41 in the direction of the arrow B, which causes a problem.

Therefore, also in this embodiment, the rotary shaft 4
It is possible to suppress both the change in the rotation characteristics of the rotor 13 due to the axial load applied to No. 1 and the rattling of the rotary shaft 41 due to the same load. Moreover, since no extra parts are required, the number of parts can be reduced.

The technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (A) The ultrasonic motor according to claim 3, wherein the elastic member is a coil spring. According to this structure, the shaft urging member can be easily formed.

[0065]

As described above in detail, according to the inventions of claims 1 to 3, the change in the rotation characteristics of the rotor due to the axial load applied to the rotating shaft and the rattling of the rotating shaft due to the same load are caused. It is possible to provide an ultrasonic motor that can suppress both, and a steering device that uses the ultrasonic motor as a drive source.

Further, according to the inventions of claims 4 to 8, it is possible to provide a steering device using an ultrasonic motor as a drive source, which can suppress discomfort to the driver.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultrasonic motor according to a first embodiment.

FIG. 2 is a partially enlarged sectional view of an ultrasonic motor.

FIG. 3 is an exploded perspective view of essential parts of the ultrasonic motor.

FIG. 4 is a diagram for explaining a load applied to a rotating shaft and a displacement amount of the rotating shaft.

FIG. 5 is a schematic configuration diagram of a steering device.

FIG. 6 is a schematic configuration diagram of a steering device according to a second embodiment.

FIG. 7 is a cross-sectional view of a main part of the steering device.

FIG. 8 is a sectional view of a main part of a steering device according to another example.

FIG. 9 is a schematic configuration diagram of a steering device according to a third embodiment.

FIG. 10 is a cross-sectional view of a main part of the steering device.

FIG. 11 is a sectional view of a conventional ultrasonic motor.

FIG. 12 is a partially enlarged sectional view of the ultrasonic motor.

FIG. 13 is a diagram for explaining a load applied to a rotary shaft and a displacement amount of the rotary shaft.

FIG. 14 is a schematic configuration diagram of a steering device.

[Explanation of symbols]

1, 20, 40 ... Ultrasonic motor as drive source, 2 ... Housing, 6, 21, 41 ... Rotating shaft, 6a, 21a, 4
1a ... Worm part, 8 ... Stator, 11 ... Piezoelectric element, 1
3 ... Rotor, 16 ... Pressure urging member, 21a ... Housing recess,
22 ... A coil spring as an elastic member forming a shaft urging member, 23 ... A collar forming a regulating member, 24 ... A thrust chip forming a regulating member, 25 ... A shaft urging member, 26 ...
Plates, 30, 31 ... Coil springs as shaft biasing members, 51 ... Car body, 52 ... Fixed bracket, 53 ... Steering column, 57 ... Nut member.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Fukui 390 Umeda, Kosai City, Shizuoka Prefecture Asmo Co., Ltd. (72) Inventor Tadayuki Suzuki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Koichi Ikeda 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Hideki Teshima 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd. (56) Reference JP-A-8-98566 (JP, A) JP 9-201081 (JP, A) JP 9-121572 (JP, A) JP 10-234189 (JP, A) JP 6-9164 (JP, A) Kaihei 7-23573 (JP, A) JP 10-66363 (JP, A) JP 10-181613 (JP, A) JP 9-240492 (JP, A) Actual Kai 4-86576 ( JP, U) (58) Survey The field (Int.Cl. ^7, DB name) H02N 2/00 B62D 1/18

Claims (8)

(57) [Claims] 1. A rotor (13) connected to a rotary shaft (21) rotatably supported by a housing (2) is attached to a stator (8) having a piezoelectric element (11) attached thereto. The pressure applying member (16) engaging with (21) is pressed against the piezoelectric element (11) to rotate the rotor (13) to rotate the rotary shaft (21). In the rotating ultrasonic motor, the rotary shaft (21) is in the same direction as the direction in which the rotary shaft (21) is biased by the biasing force of the pressure biasing member (16).
An ultrasonic motor comprising a shaft urging member (25) for urging the shaft and absorbing a load applied to the rotation shaft (21) in a direction opposite to the above direction. 2. The ultrasonic motor according to claim 1, wherein the rotary shaft (21) is formed with an accommodating recess (21a) extending in the axial direction and accommodating the shaft biasing member (25). An ultrasonic motor characterized by the above. 3. The ultrasonic motor according to claim 2, wherein the shaft urging member (25) applies an urging force to the rotating shaft (21).
2) and a regulating member (2) that elastically deforms the elastic member (22).
3, 24) and abutting against the regulating member (23, 24), the elastic member (2
An ultrasonic motor, comprising: a plate (26) fixed to the housing (2) in a state in which 2) is elastically deformed. 4. A steering column (53) supported so as to be vertically tiltable with respect to a fixed bracket (52) fixed to a vehicle body (51), the worm portion (6a,
The drive source (1, 20) for rotating the rotary shaft (6, 21) having the rotary shaft (21 a) is attached to either one side of the fixed bracket (52) or the steering column (53), and the rotary shaft (6, 21) is attached. Nut member (5) screwed to the worm part (6a, 21a) to convert the rotational motion of
7) is attached to the other side, and the steering column (53) is tilted with respect to the fixed bracket (52) by driving the drive source (1, 20). 20) is a rotor (13) connected to a rotating shaft (6, 21) rotatably supported by a housing (2) with respect to a stator (8) having a piezoelectric element (11) mounted thereon. The pressurizing member (16) engaged with the shaft (6, 21) is pressed against the shaft (6, 21) to rotate the rotor (13) based on the driving of the piezoelectric element (11), and the rotary shaft ( An ultrasonic motor (1, 20) for rotating the rotating shaft (6, 21) in the same direction as the rotating shaft (6, 21) is biased by the biasing force of the pressure biasing member (16). The rotation shaft (6, 21) is urged to the rotation shaft (6, 21). Serial steering apparatus characterized by comprising a biasing member axis for absorbing the load applied in the opposite direction (25,30,31) to the direction. 5. The steering device according to claim 4, wherein the shaft biasing member (25) is connected to the ultrasonic motor (20).
Steering device characterized by being integrated into 6. The steering device according to claim 4, wherein the shaft biasing member (30) is interposed between the nut member (57) and the housing (2) of the ultrasonic motor (1). A steering device characterized in that 7. The steering device according to claim 4, wherein the shaft urging member (31) is attached to the fixing bracket (5).
A steering device characterized by being interposed between 2) and the steering column (53). 8. A worm part (41) comprising a steering column (53) supported so as to be vertically tiltable with respect to a fixed bracket (52) fixed to a vehicle body (51).
a driving source (4) for rotating a rotating shaft (41) having a);
0) is attached to either one side of the fixed bracket (52) or the steering column (53), and the worm part (41) is used to convert the rotary motion of the rotary shaft (41) into a reciprocating linear motion.
A steering device in which a nut member (57) screwed to a) is attached to the other side, and the steering column (53) is tilted with respect to the fixed bracket (52) by the drive of the drive source (40). The drive source (40) is connected to a rotor (1) rotatably supported by a housing (2) with respect to a stator (8) to which a piezoelectric element (11) is attached.
3) is a pressure urging member (1) that engages with the rotating shaft (41).
6) are pressed against each other based on the urging force of the piezoelectric element (1)
An ultrasonic motor (40) that rotates a rotor (13) based on the drive of (1) and rotates a rotating shaft (41), wherein a load acting on the rotating shaft (41) by the weight of the tilting member. The ultrasonic motor (40) is arranged such that the direction of the rotation of the rotary shaft (41) is the same as the direction in which the rotating shaft (41) is urged by the urging force of the pressure urging member (16). Steering device.