Vibration suppression actuator

Abstract

To provide a vibration suppression actuator that is less prone to vibration attenuation in the high-frequency range within the audible range. [Solution] In the vibration suppression actuator 100, the base 161 of a rod-shaped body 160 is connected to the top of a vibration transmission body 150, and the voice coil 120 is connected to the bottom of the vibration transmission body 150. The vibration transmission body 150 of the vibration suppression actuator 100 is conical, frustoconical, polygonal pyramidal, or frustoconical.

Description

[Technical Field]

[0001] The present invention relates to a vibration suppression actuator. [Background Art]

[0002] In recent years, motors have been used as power sources for environmentally friendly electric vehicles, and there has been a strong demand to reduce high-frequency noise generated therefrom, mainly noise having frequency components from 1 kHz to 10 kHz. Furthermore, not limited to the field of electric vehicles, the application of electronic devices to general power equipment in society has increasingly caused noise in the audible frequency band to cause discomfort. In particular, noise cancellation in the 1 kHz to 10 kHz band is strongly needed.

[0003] Here, as noise cancellation methods, there are known a technology (ANC) that cancels generated noise with an anti-phase sound, and a technology (AVC) that cancels vibration that is a sound source of the generated noise (hereinafter referred to as unwanted vibration) with anti-phase vibration. ANC has not been put into practical use because reflected sound and resonant sound from the surrounding space easily act on noise of 1 kHz or higher, which complicates the construction of anti-phase sound.

[0004] As an AVC, there is known an actuator including a rod-shaped body connected to a generation source of generated noise, and a disc-shaped vibration transmitting body that transmits vibration of a voice coil to the rod-shaped body, wherein the rod-shaped body is disposed at the center of the vibration transmitting body. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-72998 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] The actuator used in the above AVC has a disc-shaped vibration transmitter, which causes split resonance within the transmitter (where vibrations separate from the voice coil vibrations occur), resulting in attenuation of vibrations transmitted to the source via the rod-shaped body below 10 kHz. Therefore, it is difficult to obtain the above-mentioned inverse-phase vibration. In this regard, if the vibration transmitter is simply made thicker to reduce split resonance, the high-frequency characteristics will still deteriorate due to internal losses and weight.

[0007] Therefore, the present invention aims to provide a vibration suppression actuator that is less prone to vibration attenuation in the high-frequency range within the audible range. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a vibration suppression actuator for suppressing unwanted vibrations occurring in a structure, comprising: a base; a rod-shaped body having a base and a connecting portion extending from the base and connected to the source of the vibration; a vibration transmitter provided at the base of the rod-shaped body; a voice coil provided at the vibration transmitter; and a magnetic field generating housing containing magnets provided inside and outside the voice coil, wherein the vibration transmitter is conical, frustoconical, pyramidal, or frustoconical, the base of the rod-shaped body is connected to the top of the vibration transmitter, and the voice coil is connected to the bottom of the vibration transmitter.

[0009] Furthermore, the vibration suppression actuator comprises a resin cap that houses the voice coil, the vibration transmitter, and the magnetic field generating housing, the cap having an opening through which the top of the vibration transmitter passes, the opening end of the cap supporting the bottom of the vibration transmitter, and the cap sealing the inside of the magnetic field generating housing and the voice coil.

[0010] Furthermore, the vibration suppression actuator is characterized in that the bottom angle θ of the vibration transmission body is between 30 and 85 degrees. [Effects of the Invention]

[0011] According to the present invention, vibration attenuation can be suppressed in the high-frequency range within the audible range. [Brief explanation of the drawing]

[0012] [Figure 1] Structure diagram (cross-sectional view) of the vibration suppression actuator of the present invention. [Figure 2] Structural diagram (cross-sectional view) of the magnetic field generating enclosure [Figure 3] Diagram (cross-section) of a vase-shaped yoke [Figure 4] Diagram of a magnet (cross-section) [Figure 5] Enlarged view (cross-sectional view) of the vibration transmission element portion of the present invention. [Figure 6] Overview diagram of the vibration suppression system (AVC) [Figure 7] A system for measuring the characteristics of a single vibration suppression actuator. [Figure 8] Frequency characteristics of a vibration suppression actuator (comparison between the present invention and a conventional product) [Figure 9] Structural diagram (cross-sectional view) of the vibration actuator of the present invention when the shape of the vibration transmitter is changed from a hollow body to a solid body. [Figure 10] Conventional actuator structure diagram (cross-sectional view) [Modes for carrying out the invention]

[0013] The vibration suppression actuator according to an embodiment of the present invention will be described below with reference to the figures.

[0014] The vibration suppression actuator according to the present embodiment is a device that suppresses unnecessary vibrations generated in a structure. Here, the structure to which the vibration suppression actuator according to the present embodiment is attached is, for example, a so-called e-axle in which a motor, an inverter, a transmission, and the like that serve as a power source for an electric vehicle are integrated and these are enclosed in a housing such as an aluminum die-cast. Further, the vibration suppression actuator according to the present embodiment is not limited to the e-axle, and may be attached to a housing that accommodates a driving body such as a motor, or a housing that accommodates a mechanical device that generates vibrations. Furthermore, it may be attached to a metal housing that generates vibrations and noise.

[0015] As shown in FIG. 1, the vibration suppression actuator 100 includes a magnetic field generating housing 110, a voice coil 120, a positioning component 130, a case 140, a vibration transmitting body 150, and a rod-shaped body 160 that is a connecting body.

[0016] As shown in FIG. 1 and FIG. 2, the magnetic field generating housing 110 is a housing that generates a magnetic field, and includes a pot-shaped yoke 111 disposed on the outer peripheral side of the voice coil 120, and a magnet 114 and a pole piece 115 disposed on the inner peripheral side of the voice coil 120.

[0017] As shown in FIG. 1 to FIG. 3, the pot-shaped yoke 111 is formed of a magnetic material, and is composed of a first accommodating portion 112 and a second accommodating portion 113. The first accommodating portion 11 accommodates the magnet 114 and the pole piece 115 inside thereof, and is formed in a circular concave shape. The first accommodating portion 112 is formed larger than the diameter of the voice coil so as to surround the voice coil 120. The second accommodating portion is provided on the opening side of the first accommodating portion, accommodates the positioning component 130 and the vibration transmitting body 150, and is formed in a circular concave shape that is wider and shallower than the first accommodating portion 112. The first accommodating portion 112 and the second accommodating portion 113 are formed such that their centers are arranged coaxially. The outer surface of the second accommodating portion 113 is connected to the inner surface of the case 140 described later.

[0018] As shown in Fig. 4, the magnet 114 has a columnar shape such as a cylinder or a prism, and uses a permanent magnet. Ferrite materials or neodymium materials are used. The upper surface of the magnet 114 is bonded to the center of the ceiling surface of the pot-shaped yoke 111. In this case, the polarity (S, N) of the magnetic field of the magnet 114 may be arbitrary, but in the present embodiment, an N pole is provided on the upper surface side and an S pole is provided on the lower surface side. When the magnet 114 is bonded to the pot-shaped yoke 111, the pot-shaped yoke 111 is magnetized to the N pole.

[0019] As shown in Fig. 4, the pole piece 115 is a magnetic body formed in a disc shape and is bonded to the lower surface of the magnet 114. By being bonded in this manner, the pole piece 115 is magnetized to the S pole. Since the pole piece 115 is arranged inside the voice coil 120, its outer shape is formed smaller than the diameter of the voice coil 120.

[0020] As described above, the magnetic field generating housing 110 is formed by bonding the pot-shaped yoke 111 to the upper part of the magnet 114 and the pole piece 115 to the lower part of the magnet 114. Here, in the magnetic field generating housing 110, a magnetic field is generated in a gap (G) formed between the pot-shaped yoke 111 and the pole piece 115. Then, the voice coil 120 is inserted into the gap.

[0021] As shown in Fig. 1, the voice coil 120 is formed by winding a conductive wire such as a copper wire or an aluminum wire around a cylindrical core material, and protecting the outside of the conductive wire with an insulating material. It is inserted into the gap (G) of the magnetic field generating housing 110. Accordingly, the magnetic field generating housing 110 is coaxially arranged with the voice coil 120. The voice coil 120 vibrates according to an electrical signal applied to the voice coil 120. The voice coil 120 is bonded to the vibration transmission housing 150.

[0022] As shown in Figure 5, the vibration transmitter 150 transmits the vibration of the voice coil 120 to the rod-shaped body 160 described later, and comprises a flange-shaped portion 151 and a frustum-shaped portion 152. Typically, the vibration transmitter 150 is formed by drawing a brass disc with a thickness of 0.5 mm to 3 mm. The flange-shaped portion 151 extends at least outward from the voice coil 120. The voice coil 120 is connected to the flange-shaped portion 151. The frustum-shaped portion 152 extends downward from the inside of the flange-shaped portion 151 (towards the opposite side from the voice coil 120) in a frustum shape. Here, the angle θ (angle consisting of the generatrix and the base) in the frustum-shaped portion 152 is preferably 45 degrees, but can be 30 to 85 degrees. Note that the vibration transmitter 150 is not limited to brass, but can be any non-magnetic metal. Furthermore, the frustum portion 152 is not limited to a cone shape, but may also be a pyramidal shape such as a triangular frustum. Also, the frustum portion 152 is not limited to a hollow shape, but may also be solid as shown in Figure 9. In this embodiment, the frustum shape includes shapes in which the inclined surface is slightly curved.

[0023] As shown in Figure 1, the positioning component 130 is made of an elastic material. The damper is annular in shape, with its outer end connected to the inner wall surface of the second housing portion 113 of the vase-shaped yoke, and its inner end connected to the flange portion 151 of the vibration transmitter 150. The positioning component can be made of springy metal, resin, or rubber material.

[0024] As shown in Figure 1, the cap 140 closes the opening of the vase-shaped yoke 111 and is composed of a peripheral wall portion 141 and a bottom portion 142. The peripheral wall portion 141 is formed in a cylindrical shape so as to be in close contact with the outer surface of the second housing portion 113 of the vase-shaped yoke 111. The cap 140 and the vase-shaped yoke 111 are bonded together with an adhesive or the like. The bottom portion 142 is formed in an annular shape so as to close the opening of the second housing portion 113 of the vase-shaped yoke 111. Here, the vibration transmitter 150 is passed through the opening formed in the bottom portion 142 so as to protrude from the cap 140. Here, the flange portion 151 of the vibration transmitter 150 is bonded to the opening end of the bottom portion 142 with an adhesive or the like. The cap 140 is typically made of reinforced resin such as POM and is formed to a thickness of 0.5 to 4 mm. The cap 140 is not limited to being made of reinforced resin such as POM, but may be formed from other resins. Here, because the resin material has a low Q value as a damping coefficient, it can reduce the effect of abnormal resonance inside the vibration transmitter 150 and reduce phase distortion. Also, as mentioned above, the peripheral wall portion 141 of the cap 140 is connected to the outer wall of the magnetic field generating housing 110, and the bottom portion 142 is connected to the vibration transmitter 150. In other words, the magnetic field generating housing 110 and the vibration transmitter 150 are connected via the cap 140, and the bottom portion 142 of the cap 140 functions as a damper that dampens the vibration of the vibration transmitter 150.

[0025] As shown in Figure 1, the rod-shaped body 160 is cylindrical, cylindrical or polygonal in shape, with its base end 161 connected to the top of the vibration transmitter 150 and its tip end 162 connected to the structure to be vibration-suppressed (where unwanted vibrations occur). The rod-shaped body 160 may have threads on its outer circumference if it is cylindrical, or it may have threads on its inner circumference if it is cylindrical. The rod-shaped body 160 is preferably made of brass, but a non-magnetic metal may also be used. The diameter of the rod-shaped body 160 is ideally 2 to 16 mm, although point excitation is the ideal. By connecting the rod-shaped body 160 to the structure to be vibration-suppressed, the vibration force from the vibration transmitter 150 is transmitted to the structure to be vibration-suppressed.

[0026] The terminals of the voice coil 120 are located on the pot-shaped yoke 110, and signals from the control device 170 shown in Figure 6 are input to these terminals. The control device 170 includes a vibration sensor 171 that detects unwanted vibrations occurring in the vibration suppression target S, and a signal generation unit (not shown) that generates a signal to be input to the voice coil 120 based on the vibrations detected by the vibration sensor 171. The vibration sensor 171 detects unwanted vibrations in real time, and the signal generation unit generates a signal in real time that is out of phase with the vibrations detected by the vibration sensor. The method of generating the signal is not particularly limited and can be analog or digital. Thus, the vibration suppression system is configured by the vibration suppression actuator 100 and the control device 170.

[0027] In the vibration suppression system described above, a control device 170 generates a signal that is out of phase with the unwanted vibrations generated from the structure S, and this signal is input to the vibration suppression actuator 100. The vibration suppression actuator 100 then generates a vibration (suppression vibration in Figure 6) that is out of phase with the unwanted vibrations based on the signal input from the control device 170, and applies this vibration to the source of the unwanted vibrations (the vibration suppression target S). Because the vibration transmission body 150 of the vibration suppression actuator 100 is formed in a frustum shape, partial resonance is suppressed, and as a result, the attenuation of the suppression vibration in the high-frequency band within the audible range is reduced. Therefore, noise generated from the structure (vibration suppression target S) can be efficiently canceled.

[0028] Here, a comparative experiment was conducted between a conventional vibration suppression actuator 300 (Figure 10) and the vibration suppression actuator 100 according to this embodiment. As shown in Figure 7, the comparative experiment used a signal source that generates signals from 500 to 300 kHz. The rod-shaped bodies 360 and 160 of the vibration suppression actuators 300 and 100 were connected at their tips to an aluminum plate S, which was the target of vibration suppression. In the comparative experiment, the frequency of the signal output from the signal source was gradually increased, and the sound generated from the aluminum plate was collected by a microphone placed near the aluminum plate. The output of the microphone was input to a gain-phase analyzer. The frequency characteristics of the gain and phase were then confirmed using the gain-phase analyzer.

[0029] The conventional vibration suppression actuator 300 exhibited a gradual decrease in gain above 7 kHz, and also experienced phase rotation above 7 kHz. In this embodiment, the vibration suppression actuator 100 did not experience gain attenuation or phase rotation between 1 kHz and 10 kHz. However, above 20 kHz, the gain gradually decreased and phase rotation occurred. Although the frequency response below 700 Hz is attenuated, this is not a problem in this embodiment because the actuator is designed to generate vibrations in the 1 kHz to 10 kHz band.

[0030] Although embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and may also be modified in the following ways, for example.

[0031] The vibration transmitter 150 is not limited to a frustoconical or truncated pyramidal shape, but may also be conical or pyramidal.

[0032] Cap 140 is not limited to being made of resin; it may also be made of metal. [Explanation of Symbols]

[0033] 100 Inventive Product: Vibration Suppression Actuator 110 Magnetic field generating enclosure 111 Urn-shaped York 112 The first containment section of the pot-shaped yoke 113 The second containment unit of the jar-shaped York 114 Magnets 115 pole pieces 120 Voice Coil 130 Positioning parts 140 cases 141 Peripheral wall of the case 142 Bottom of the case 150 Vibration Transmitter 151 Flange-shaped part of vibration transmitter 152 The frustum portion of the vibration transmitter 160 rod-shaped body 161 Joint (base end) of the rod-shaped body with the vibration transmitter 162 The joint (tip) of the rod-shaped object with the noise source. 170 Control device 171 Vibration Sensor 200 Inventive Product: Vibration Actuator (Modified Version) 210 Magnetic field generating enclosure 220 Voice Coil 230 Positioning parts 240 cases 250 Vibration transmitter (changed from hollow to solid) 260 rod-shaped body 300 Conventional Actuator 310 Magnetic field generating enclosure 320 Voice Coil 330 Damper 250 Vibration Transmitter 260 rod-shaped body G gap where magnetic field G is generated S Vibration suppression target

Claims

1. A vibration suppression actuator that suppresses unwanted vibrations occurring in a structure, A rod-shaped body having a base and a connecting portion extending from the base and connected to the vibration source, A vibration transmitter provided at the base of the rod-shaped body, A voice coil provided in the vibration transmission body, A magnetic field generating housing that includes magnets provided on the inside and outside of the voice coil, Equipped with, The vibration transmitter is conical, frustoconical, polygonal pyramidal, or polygonal frustoconical, A vibration suppression actuator characterized in that the base of the rod-shaped body is connected to the top of the vibration transmission body, and the voice coil is connected to the bottom of the vibration transmission body.

2. The system comprises a resin cap that houses the voice coil, the vibration transmitter, and the magnetic field generating housing, The cap is provided with an opening through which the top of the vibration transmitter passes. The open end of the cap supports the bottom of the vibration transmitter. The vibration suppression actuator according to claim 1, characterized in that the cap seals the inside of the magnetic field generating housing and the voice coil.

3. The vibration suppression actuator according to claim 1, characterized in that the bottom angle θ of the vibration transmitter is between 30 and 85 degrees.

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