JP2000016300A - Vibration damping device for steering wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce the vibration of a steering wheel without enlarging the cross section of the frame member of the steering wheel or depending on a dynamic damper. SOLUTION: A vibration damping device for a steering wheel has piezoelectric conversion elements 11 placed in close contact with the surface of the frame member of the steering wheel, a vibration detecting sensor 8 for detecting the vibration of the frame member, and a control means 9 applying voltages proportional to the output of the vibration detecting sensor to the piezoelectric conversion elements. The vibration detecting sensor is placed on a rim portion 2 and the piezoelectric conversion elements are placed at spoke portions 4-7 connecting a mounting portion 3 for a steering shaft to the rim portion. Therefore, the spoke portions serving as the path of transmission of vibration from the steering shaft to the rim portion are excited by the exciting forces of the piezoelectric conversion elements in such a manner as to suppress the vibration of the rim portion to selectively damp the vibration of the rim portion where the driver gripping it directly feels the vibration, thereby reducing with high efficiency the discomfort caused by the vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a vibration damping device for a steering wheel.

[0002]

2. Description of the Related Art In order to reduce unpleasant vibration generated in a steering wheel during running or idling, it is general to increase the rigidity of a frame material. This is to reduce the vibration in the normal range by raising the natural vibration value. Another method is to attach a dynamic damper to lower the frequency response near the natural vibration value.

[0003]

However, the method of increasing the rigidity of the frame material involves increasing the weight mainly due to the increase in the cross section of the frame material, and also reduces the ability to protect the occupant in the event of a collision. There are inconveniences. Moreover, it is difficult to secure ideal rigidity in order to secure a space for installing various devices and switches in the center of the steering wheel. On the other hand, in the method using the dynamic damper, a relatively large installation space is required, and an increase in weight due to the mass member is inevitable. In addition, there is an inconvenience that the damping ability is reduced due to the aging of the spring member.

[0004]

SUMMARY OF THE INVENTION In order to solve such a problem and to provide a vibration damping device for a steering wheel capable of effectively suppressing vibration, the present invention provides a vibration damping device for a steering wheel. The configuration includes a piezoelectric conversion element 11 arranged in close contact with the surface of the frame material of the steering wheel, a vibration detection sensor 8 for detecting vibration of the frame material, and a voltage corresponding to the output of the vibration detection sensor to the piezoelectric conversion element. Control means 9 for applying the vibration, a vibration detection sensor is arranged on the rim part 2, and a piezoelectric conversion element is arranged on the spoke parts 4 to 7 connecting the attachment part 3 to the steering shaft and the rim part, Vibration of the rim is suppressed by excitation of the spoke by the piezoelectric transducer.

According to this, based on the vibration of the rim portion detected by the vibration detection sensor, the spoke portion corresponding to the transmission path of the vibration from the steering shaft to the rim portion is formed.
Vibration is generated by the vibrating force of the piezoelectric transducer so as to suppress the vibration of the rim, and by selectively damping the rim that the driver grasps and feels the vibration directly, the discomfort due to vibration is reduced. It can be reduced with high efficiency.

[0006] Incidentally, as the piezoelectric conversion element, PZ is used.
T (zirconate titanate), PLZT (lanthanum zirconate titanate), PMN (magnesium niobium lead oxide), PVDF (polyvinylidene fluoride) and the like are used. The vibration detection sensor is not particularly limited as long as it can appropriately detect the vibration generated in the rim portion and does not affect the posture change due to the rotation of the rim portion. Or an accelerometer that detects a strain generated in a mass support portion by a piezoelectric element or a semiconductor. In addition, a configuration in which the distortion generated in the rim portion is directly detected by the distortion sensor is also possible.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a steering wheel frame to which the present invention is applied. The frame of the steering wheel includes a rim 2 having a grip portion 1 made of synthetic resin, which is gripped by a driver, integrally formed therearound, a base plate 3 connected to a steering shaft (not shown), and the base plate 1 and the rim 1. It comprises a pair of lateral spokes 4 and 5 extending in the horizontal direction to interconnect with each other and a pair of vertical spokes 6 and 7 extending in the vertical direction. An airbag assembly (not shown) is mounted on the front side of the base plate 3.

The rim 2 is formed by bending a metal pipe and welding both ends. A vibration detection sensor 8 for detecting the vibration of the rim 2 is disposed at the top of the rim 2 where the vibration having the largest amplitude occurs.

Each of the spokes 4 to 7 is formed by bending a metal plate having a predetermined shape, and has an inner end welded to the front surface of the base plate 3 and an outer end formed on the inner periphery of the rim 2. Welded to the surface. Spoke 4 ~
A piezoelectric actuator 11 in the shape of a rectangular flat plate is arranged near the inner end of each of the piezoelectric actuators 7.

The piezoelectric actuator 11 vibrates the spokes 4 to 7 with required vibration characteristics by a control voltage from the amplifier 10 according to the output signal of the control circuit 9. As shown in FIG. The electrodes 13a and 1 having different polarities are provided in the piezoelectric transducer 12 which generates a load according to
3b has a laminated structure in which the electrodes are arranged alternately, thereby narrowing the interval between the electrodes to obtain a high electric field at a low voltage.

As shown in FIG. 3, the piezoelectric actuators 11 are arranged in a bimorph shape on both the front and back surfaces of the spokes 4 to 7, and are in close contact with the front and back surfaces of the spokes 4 to 7 via the adhesive 14. Fixed. Here adhesive 14
Are metal spokes 4 to 7 and piezoelectric actuator 11
It also has the function of electrical insulation between them. In addition, a mode in which the piezoelectric actuator 11 is provided in a unimorph shape on one surface of the spokes 4 to 7 is also possible, but a bimorph is advantageous in obtaining a large vibrating force.

A control voltage is applied to the piezoelectric actuator 11 so that the front and back sides have opposite phases, and a bending moment is generated in the spokes 4 to 7 so that the spokes 4 to 7 have a required frequency.
To excite. For example, a compressive load is generated on the piezoelectric conversion element of the front piezoelectric actuator 11 as shown by an arrow A, and a tensile load is generated on the piezoelectric conversion element of the back piezoelectric actuator 11 as shown by an arrow B. , A bending moment in the direction indicated by the arrow C can be generated in the spokes 4 to 7. If the opposite tensile and compressive loads are generated in the front and back piezoelectric actuators 11, respectively, a bending moment in the opposite direction to the above is generated.
~ 7.

As described above, the piezoelectric actuator 11
When vibration is input from the steering shaft to the steering wheel on which is mounted, the vibration detection sensor 8 detects the vibration generated on the rim 2 as shown in FIG. Control circuit 9 based on
In, arithmetic processing is performed in accordance with a transfer function obtained in advance by experiment or simulation, and the control circuit 9 outputs a control signal having a frequency characteristic capable of suppressing vibration of the rim 2. Then, a control voltage corresponding to the control signal is applied from the amplifier 10 to the piezoelectric conversion element of the piezoelectric actuator 11, and the spokes 4 to 7 are vibrated in the manner described above. Thereby, the vibration of the rim 2 is suppressed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The results of an experiment on damping vibrations of the steering wheel having the above-described configuration are shown below. Here, pitching was applied on the vibration bench in a direction perpendicular to the axis of the steering shaft. FIG. 5 shows measured power spectra (frequency characteristics) at the time of control and at the time of non-control at this time. According to this, the frequencies 82.8 Hz, 142.8 Hz and 24
The vibration level at the peak generated at 1.2 Hz is reduced by about 20 dB by the vibration suppression control according to the present invention.
It has been found that the vibration of the rim 2 can be effectively reduced.

Of these, the second highest peak frequency 14
FIG. 6 shows a vibration suppression state (time response) of the rim 2 at 2.8 Hz. Here, the output voltage V _{u1 of} the amplifier 10 corresponding to the piezoelectric actuators 11 of the horizontal spokes 4 and 5 is shown in the upper stage.
And the piezoelectric actuators 11 of the vertical spokes 6 and 7 in the middle stage.
, The output voltage V _u2 of the amplifier 10 corresponding to the above is shown in the lower row, and the output voltage V _y of the vibration detection sensor 8 is shown in the lower part.

In order to obtain the above control action, the horizontal spokes 4 and 5 and the vertical spokes 6 and 7 perform different controls on the piezoelectric actuator 11, and the frequency characteristics (transfer function) at that time. Is shown in FIG. As described above, effective vibration suppression can be achieved by performing different control in which the frequency characteristics and the output level are changed in accordance with the positional relationship between the spokes 4 to 7 with respect to the vibration detection sensor 8 and the support form of the rim 2.

[0018]

As described above, according to the present invention, the spoke, which is the transmission path of the vibration from the steering shaft to the rim, is vibrated by the vibrating force of the piezoelectric transducer so as to suppress the vibration of the rim. By selectively damping the rim that the user grips and feels the vibration directly, the discomfort due to the vibration can be efficiently reduced. Since the piezoelectric transducer can generate a large vibrating force even in a small size and has high durability, a great effect can be obtained in solving problems in weight, durability, and installation space. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a frame of a steering wheel to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a piezoelectric actuator.

FIG. 3 is a cross-sectional view of a main part showing the arrangement of piezoelectric actuators.

FIG. 4 is a block diagram illustrating a control method.

FIG. 5 is a graph showing measured power spectra (frequency response) during control and during non-control.

FIG. 6 is a graph showing a temporal change (time response) of a drive amplifier output and a vibration detection sensor output of a piezoelectric actuator.

FIG. 7 is a graph showing a frequency characteristic (transfer function) of the control circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grip part 2 Rim 3 Base plate 4.5 Horizontal spokes 6 Vertical spokes 8 Vibration detection sensor 9 Control circuit 10 Amplifier 11 Piezoelectric actuator 12 Piezoelectric conversion element 13a / 13b Electrode 14 Adhesive

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yuta Urushiyama 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. 3D030 DB07

Claims (1)

[Claims] A piezoelectric conversion element disposed in close contact with a surface of a frame member of a steering wheel; a vibration detection sensor for detecting vibration of the frame member; and a voltage corresponding to an output of the vibration detection sensor. Control means for applying a voltage to the conversion element, wherein the vibration detection sensor is disposed on a rim, and the piezoelectric conversion element is disposed on a spoke that interconnects the rim and an attachment to a steering shaft. The vibration of the rim portion is suppressed by the vibration of the spoke portion by the piezoelectric conversion element.