Vibration actuator

Abstract

This disclosure includes: a case; a cylindrical voice coil housed in the case and fixed to the case; a magnetic circuit housed in the case, capable of generating a magnetic field reaching the voice coil, reciprocating in an axial direction of the voice coil with respect to the case when a current flows through the voice coil, and including at least a magnet; and dampers 55A, 55B connecting the case and the magnetic circuit so that the magnetic circuit can reciprocate in the axial direction. The damper includes: a base material 56 made of cloth; and a rubber material 59 integrated with the base material and having an internal loss larger than that of the base material.

Description

Vibration actuator

[0001] This disclosure relates to a vibration actuator.

[0002] The vibration actuator disclosed in Japanese Patent No. 7124203 includes a mounting member, a metal damper (elastic support) supported by the mounting member, a cylindrical coil fixed to the mounting member via a bobbin, and a magnetic circuit (movable element) supported by the damper. The magnetic circuit includes a yoke and a magnet. The coil is disposed in a magnetic field generated by the magnetic circuit.

[0003] When an electric current flows through the coil, the magnetic circuit reciprocates along the axial direction of the coil with respect to the coil and the mounting member. Therefore, the vibration actuator vibrates.

[0004] However, the metallic damper has low internal loss, making stable control difficult, and it is difficult to maintain the long-term reliability of the vibration actuator due to destruction caused by metal fatigue. Also, even for a damper using a cloth material with a large internal loss, it is difficult to maintain the long-term reliability of the vibration actuator due to sagging.

[0005] An object of this disclosure is to provide a vibration actuator with excellent long-term reliability.

[0006] The vibration actuator according to the first aspect includes a case, a cylindrical voice coil housed in and fixed to the case, a magnetic circuit including at least a magnet housed in the case and capable of generating a magnetic field reaching the voice coil, and when an electric current flows through the voice coil, the magnetic circuit reciprocates in the axial direction of the voice coil with respect to the case, and a damper connecting the case and the magnetic circuit so that the magnetic circuit can reciprocate in the axial direction. The damper has a base material made of cloth and a rubber material integrated with the base material and having a larger internal loss than the base material.

[0007] The damper of the vibration actuator in the first embodiment has a base material made of cloth and a rubber material integrated with the base material and having a greater internal loss than the base material. Therefore, this damper can obtain mechanical resistance by utilizing the loss of the rubber material and maintain long-term reliability. Furthermore, this damper can have a greater internal loss than a damper made of a base material alone. Therefore, the vibration actuator described in claim 1 has a configuration in which a magnetic circuit including a magnet is supported by a damper including cloth, yet it is possible to lower the Q value (Quality Factor).

[0008] In the second embodiment of the vibration actuator, the rubber material is foamed rubber, as in the first embodiment.

[0009] In the second embodiment of the vibration actuator, the damper can be made lighter because the rubber material is foamed rubber.

[0010] In the third embodiment of the vibration actuator, the rubber material is provided on both sides of the base material in the thickness direction, as in the first or second embodiment.

[0011] In the third embodiment of the vibration actuator, rubber material is provided on both sides of the base material. Therefore, compared to the case where rubber material is provided on only one side of the base material, the internal loss of the damper tends to be larger, and warping of the damper is less likely to occur.

[0012] In the fourth embodiment, the vibration actuator, in any one of the first to third embodiments, has a portion of the rubber material inserted into the gaps between the fibers constituting the cloth.

[0013] In the vibration actuator of the fourth embodiment, the rubber material is embedded in the gaps between the fibers that make up the fabric, so the internal loss of the damper is large.

[0014] In the fifth embodiment of the vibration actuator, in any one of the first to third embodiments, the plurality of dampers arranged in the axial direction are connected to the case and the magnetic circuit.

[0015] The vibration actuator of the fifth embodiment can vibrate the magnetic circuit in a more stable state compared to the case with only one damper.

[0016] The vibration actuator of the sixth embodiment has two dampers in the fifth embodiment.

[0017] The vibration actuator of the sixth embodiment can vibrate the magnetic circuit in a more stable state compared to the case with only one damper.

[0018] In the seventh embodiment, the vibration actuator, in the sixth embodiment, has two dampers that are symmetrical with respect to a virtual plane perpendicular to the axis.

[0019] In the seventh embodiment of the vibration actuator, since the two dampers are symmetrical with respect to a virtual plane, the magnetic circuit can be vibrated in a more stable state compared to the case where the two dampers are not symmetrical.

[0020] The vibration actuator of the eighth embodiment is characterized in that, in any one of the first to seventh embodiments, the damper has an annular shape centered on the axis of the voice coil.

[0021] The vibration actuator of the eighth embodiment allows the magnetic circuit to vibrate in a more stable manner compared to the case where the damper has an asymmetric shape with respect to the axis of the voice coil.

[0022] In the vibration actuator described in the ninth aspect, in any one of the first to eighth aspects, the rubber material is provided on a portion of the substrate excluding the connecting end, which is the end on the magnetic circuit side of one surface in the thickness direction of the substrate, and the connecting end is bonded to the magnetic circuit.

[0023] In the vibration actuator of the ninth embodiment, since the base material made of cloth is bonded to the magnetic circuit, it is easier to increase the bonding strength between the damper and the magnetic circuit compared to the case where rubber material is bonded to the magnetic circuit.

[0024] The vibration actuator of this disclosure exhibits excellent long-term reliability.

[0025] This is a perspective view of the vibration actuator according to the embodiment and a vehicle seat on which the vibration actuator is mounted, viewed from the front. This is a perspective view of the vibration actuator. This is a cross-sectional view taken along the central axis of the vibration actuator. This is a perspective view showing a cross-section taken along the central axis of the vibration actuator. This is a perspective view of the damper. This is a cross-sectional view of a part of the damper. This is a schematic cross-sectional view showing how the damper is manufactured by a press device. This is a flowchart showing the manufacturing method of the damper. This is a graph showing the experimental results of the vibration actuator according to the embodiment. This is a cross-sectional view showing a part of the vibration actuator according to the first modified example. This is a cross-sectional view showing a part of the vibration actuator according to the second modified example. This is a cross-sectional view showing a part of the vibration actuator according to the third modified example. This is a cross-sectional view showing a part of the vibration actuator according to the fourth modified example. This is a cross-sectional view showing a part of the vibration actuator according to the fifth modified example.

[0026] The vibration actuator 10 according to the embodiment will be described below with reference to Figures 1 to 9.

[0027] As shown in Figures 2 to 4, the vibration actuator 10 comprises a case 20, a voice coil 30, a magnetic circuit (movable element) 40, and dampers 55A and 55B.

[0028] Case 20 comprises a first component 21, a second component 23, and a third component 26. The first component 21, the second component 23, and the third component 26 are substantially rotationally symmetrical about the axis 20C of case 20. The first component 21, the second component 23, and the third component 26 are made of a resin material such as ABS. In the following description, "one side" and "the other side" in the direction along the axis 20C refer to the directions shown in Figures 2 to 4. Furthermore, unless otherwise specified, "one side" and "the other side" in the following description refer to directions relative to the axis 20C.

[0029] The first component 21 is a hollow cylindrical member with a bottom and an open end face on one side. The second component 23 is a hollow cylindrical member with open end faces on both sides of the axis 20C, and has three projections 24 on its outer circumference at equal angular intervals in the circumferential direction. A through hole 25 is formed in each projection 24. The third component 26 is a hollow cylindrical member with a bottom and an open end face on the other side. As shown in Figure 2, the third component 26 has two insertion holes 27.

[0030] As shown in Figures 3 and 4, one end of the voice coil 30 is fixed to the ceiling surface of the third component 26. The voice coil 30 has a substantially cylindrical bobbin 31 with its axis 30C approximately at its center, and a substantially cylindrical coil 32 wound around the outer circumference of the bobbin 31.

[0031] Furthermore, a pair of metal terminals (not shown) are inserted into each insertion hole 27 shown in Figure 2. The inner end of one terminal is connected to one end of the wire constituting the coil 32, and the inner end of the other terminal is connected to the other end of the wire. Furthermore, one end of the electrical cable 35 shown in Figure 2 is connected to one terminal, and one end of the electrical cable 36 is connected to the other terminal. The other ends of the electrical cables 35 and 36 are connected to an AC power supply (not shown) via a control device (not shown).

[0032] As shown in Figures 3 and 4, the magnetic circuit 40 comprises a yoke 42, a magnet 47, and a pole piece 49.

[0033] The yoke 42, which is made of a soft magnetic material, is rotationally symmetric about its axis 42C. A magnetic gap 44, which is an annular groove centered on the axis 42C, is formed on one end face of the yoke 42. Furthermore, an annular recess 45 centered on the axis 42C is formed on the outer circumference of one end face of the yoke 42, and an annular recess 46 centered on the axis 42C is formed on the outer circumference of the other end face of the yoke 42.

[0034] A magnet 47, which is an annular hard magnetic material (permanent magnet), is fixed to one end face of the yoke 42. The magnet 47 is a neodymium magnet. One side of the magnet 47 is the south pole, and the other side is the north pole.

[0035] An annular pole piece 49 is fixed to one end face of the magnet 47.

[0036] The symbol G shown in Figure 3 is the center of gravity of the integrated structure comprising the yoke 42, magnet 47, and pole piece 49.

[0037] The pair of dampers 55A and 55B have the same structure. More specifically, dampers 55A and 55B are symmetrical with respect to the virtual plane 20P, which will be described later. Therefore, in the following explanation, damper 55A will be described in detail, and a detailed explanation of damper 55B will be omitted.

[0038] As shown in Figures 3 to 6, the damper 55A is substantially rotationally symmetric about the axis 20C. That is, the damper 55A is an annular member. The damper 55A is an integrally molded product having a base material 56 and a rubber material 59.

[0039] The damper 55A is manufactured using the press device 70 shown in Figure 7. The press device 70 comprises a fixed lower die 71, a movable upper die 75, an actuator (not shown) for moving the upper die 75 vertically, and a heating device for heating the lower die 71 and the upper die 75. The inner surface (bottom surface) of the lower die 71 has a molding surface 72 having three annular protrusions 73, and the bottom surface of the upper die 75 has a molding surface 76 having three annular recesses 77.

[0040] When manufacturing the damper 55A, first, as shown in step S10 (the word "step" will be omitted hereafter) of the flowchart in Figure 8, a cloth (not shown) is set on the molding surface 72 of the lower mold 71, which is separated from the upper mold 75. The lower mold 71 and the upper mold 75 are heated by a heating device. This cloth is a woven fabric made of yarn. This cloth has a structure in which phenolic resin is impregnated into yarn made of, for example, chemical fibers. As a chemical fiber, for example, aramid can be used.

[0041] Next, as shown in S11 of the flowchart, the upper mold 75 is moved downward using an actuator to clamp the mold. This clamped state is maintained for a predetermined time.

[0042] Subsequently, as shown in S12 of the flowchart, the upper mold 75 is moved upward using an actuator to open the mold. As a result, the substantially annular base material 56 shown in FIG. 7 is manufactured. On this base material 56, three concentric annular ridges 56A, 56B, and 56C formed by the annular convex portion 73 and the annular concave portion 77 are formed.

[0043] Subsequently, as shown in S13 of the flowchart, foamed rubber (raw rubber containing a foaming material) 61 is placed on the molding surface 72 of the lower mold 71 (see the phantom line in FIG_7), and further, the base material 56 is set on the molding surface 72 from above the foamed rubber 61. Further, foamed rubber 61 is also placed on the upper surface of the base material 56 (see the phantom line in FIG_7). The foamed rubber 61 is made of, for example, EPDM (ethylene propylene rubber), SBR (styrene butadiene rubber), or NBR (nitrile rubber), and by heating and pressurizing the raw rubber containing the foaming material, foamed rubber containing a bubble portion inside is formed.

[0044] Subsequently, as shown in S14 of the flowchart, the upper mold 75 is moved downward using an actuator to close the mold. This mold closing state is maintained for a predetermined time.

[0045] Next, as shown in S15 of the flowchart, the upper mold 75 is moved upward using an actuator to open the mold. This completes an intermediate damper 55A in which the entire surface of the base material 56 is covered with rubber material 59. At this time, a skin layer that does not contain air bubbles is formed on the surface of the rubber material 59 that contains air bubbles. In other words, the intermediate damper 55A is manufactured by insert molding using the lower mold 71 and the upper mold 75. Finally, in the cutting process shown in S16, the inner and outer circumferences of the intermediate are trimmed, and air vent holes 56E are formed, completing the damper 55A shown in Figure 5. As shown in Figure 5, the damper 55A has three concentric annular protrusions 57A, 57B, and 57C formed by annular protrusions 73 and annular recesses 77. Furthermore, three air vent holes 57E are formed in the damper 55A. A portion of the rubber material 59 enters the gaps between the threads that make up the base material 56. In other words, the portion of the rubber material 59 that covers one side of the base material 56 in the thickness direction and the portion that covers the other side of the base material 56 in the thickness direction are connected by multiple portions of the rubber material 59 that have entered into numerous gaps.

[0046] The dampers 55A and 55B manufactured in this manner are fixed to the yoke 42. Specifically, as shown in Figures 3 and 4, the inner end of damper 55A is placed over the annular recess 45 of the yoke 42, and the annular recess 45 and the inner end of damper 55A are fixed together with a heat-resistant adhesive. Furthermore, the inner end of damper 55B is placed over the annular recess 46 of the yoke 42, and the annular recess 46 and the inner end of damper 55B are fixed together with a heat-resistant adhesive.

[0047] Next, the yoke 42, magnet 47, pole piece 49, and dampers 55A and 55B are integrated with the first component 21, second component 23, and third component 26.

[0048] First, the yoke 42 is positioned within the internal space of the second component 23. The outer peripheral side end of the damper 55A is placed on the upper end surface of the second component 23, and the outer peripheral side end of the damper 55B is brought into contact with the lower end surface of the second component 23. Further, the outer peripheral side end of the damper 55A and the upper end surface of the second component 23 are fixed by a heat-resistant adhesive, and the outer peripheral side end of the damper 55B and the lower end surface of the second component 23 are fixed by a heat-resistant adhesive.

[0049] Subsequently, as shown in FIG. 3, the second component 23 is placed over the upper end surface of the first component 21. Further, with the outer peripheral side end of the damper 55B sandwiched between the lower end surface of the second component 23 and the upper end surface of the first component 21, the first component 21 and the second component 23 are fixed. The fixing means for the first component 21 and the second component 23 is not limited to a specific one. This fixing means may be, for example, a mechanical fixing means or an adhesive. Thereby, the outer peripheral side end of the damper 55B is firmly fixed by the first component 21 and the second component 23.

[0050] Subsequently, as shown in FIG. 3, the third component 26 is placed over the upper end surface of the second component 23. At this time, as shown in FIG. 3, the lower part of the voice coil 30 is inserted into the magnetic gap 44 of the yoke 42 so as to be relatively movable. In other words, the magnet 47 and the pole piece 49 are arranged within the internal space of the bobbin 31. Further, with the outer peripheral side end of the damper 55A sandwiched between the lower end surface of the third component 26 and the upper end surface of the second component 23, the second component 23 and the third component 26 are fixed. The fixing means for the second component 23 and the third component 26 is not limited to a specific one. This fixing means may be, for example, a mechanical fixing means or an adhesive. Thereby, the outer peripheral side end of the damper 55A is firmly fixed by the second component 23 and the third component 26. Thereby, the vibration actuator 10 is completed.

[0051] When the vibration actuator 10 is assembled in this manner, the axis 20C of the case 20, the axis 42C of the yoke 42, and the axis 30C of the voice coil 30 substantially coincide with each other. Furthermore, when no electricity flows through the coil 32 and the electrical cables 35 and 36, the dampers 55A and 55B are substantially symmetrical with respect to a virtual plane 20P, which is a plane perpendicular to the axis 20C shown in Figure 3 and passing through the center of gravity G.

[0052] Next, the operation and effects of the embodiment will be described.

[0053] As shown in Figure 1, in this embodiment, multiple vibration actuators 10 are fixed to members provided inside the seat cushion 101 and seat back 102 of the vehicle seat 100. For example, each vibration actuator 10 is fixed to the seat cushion 101 and seat back 102 by screwing a bolt (not shown) inserted into a through hole 25 of each projection 24 into a female threaded hole formed in a metal member provided inside the seat cushion 101 and seat back 102.

[0054] The vibration actuator 10 comprises a magnetic circuit 40 including a yoke 42, a magnet 47, and a pole piece 49, and a cylindrical voice coil 30 disposed in the magnetic field generated by the magnetic circuit 40 and supplied with AC power via a control device. When AC current is supplied to the voice coil 30, the magnetic circuit 40 reciprocates along the axis 20C (axis 42C) relative to the case 20, deforming the dampers 55A and 55B. At this time, the annular protrusions 57A, 57B, and 57C of the dampers 55A and 55B and their surrounding parts are deformed particularly significantly. The force due to the reciprocating movement of the magnetic circuit 40 is transmitted to the case 20 via the dampers 55A and 55B, and further transmitted from the case 20 to the seat cushion 101 and seat back 102. Therefore, for example, if each vibration actuator 10 is vibrated in sync with music output at low frequencies by the sound equipment of a vehicle equipped with a vehicle seat 100, the occupants can obtain an immersive sound effect.

[0055] Furthermore, the dampers 55A and 55B of the vibration actuator 10 have a base material 56 made of cloth and a rubber material 59 integrated with the base material 56. Moreover, the rigidity of the rubber material 59 is lower than that of the base material 56, and therefore the internal loss (loss tangent tanδ) of the rubber material 59 is greater than that of the base material 56. As a result, the dampers 55A and 55B have a greater internal loss than dampers made of only the base material 56. Therefore, the dampers 55A and 55B can obtain mechanical resistance by utilizing the loss of the rubber material 59, and can maintain long-term reliability. Furthermore, the vibration actuator 10 is able to lower the Q value (Quality Factor) even though it is configured to support a magnetic circuit 40 including a yoke 42, magnet 47 and pole piece 49 with dampers 55A and 55B that include a base material 56 made of cloth. In the graph of Figure 9, the horizontal axis represents the vibration frequency of the vibration actuator 10, and the vertical axis represents the acceleration of the vibration of the vibration actuator 10. The graph shown with dashed lines (two-dot dashed lines) represents the vibration of a comparative example vibration actuator to which a damper consisting only of the base material 56 is applied, while the graph shown with solid lines represents the vibration of the vibration actuator 10 of this embodiment. As is clear from these graphs, the comparative example vibration actuator vibrates with a large acceleration in a predetermined vibration frequency band B. In contrast, the acceleration of the vibration actuator 10 of this embodiment in vibration frequency band B is smaller than that of the comparative example. In particular, the acceleration at the lowest resonant frequency f0 of the vibration actuator 10 can be significantly reduced compared to the acceleration at the lowest resonant frequency f0-a of the comparative example vibration actuator. Vibration frequency band B corresponds to the range of vibration frequencies of the vibration actuator 10 when it is actually used.

[0056] Furthermore, since the dampers 55A and 55B of the vibration actuator 10 include a base material 56 that is more rigid than the rubber material 59, the force caused by the reciprocating movement of the magnetic circuit 40 can be reliably transmitted to the case 20.

[0057] Furthermore, since air vents 56E are formed in the dampers 55A and 55B, when the dampers 55A and 55B, whose surfaces are covered with a highly airtight rubber material 59, deform in accordance with the vibration of the magnetic circuit 40, it is possible to prevent the air inside the case 20 from functioning as an air spring. As a result, the vibration actuator 10 can be vibrated stably.

[0058] Furthermore, the dampers 55A and 55B have a structure in which rubber material 59 is provided on both sides of the base material 56 in the thickness direction. Because rubber material 59 is provided on both sides of the base material 56, warping is less likely to occur in the dampers 55A and 55B.

[0059] Furthermore, numerous portions of the rubber material 59 penetrate into the gaps between the threads that make up the base material 56 of the dampers 55A and 55B. In other words, the dampers 55A and 55B have a larger amount of rubber material 59 compared to the case where rubber does not penetrate into the gaps between the fibers that make up the fabric. Therefore, the internal loss of the dampers 55A and 55B can be increased.

[0060] Furthermore, since the dampers 55A and 55B are manufactured by insert molding using foamed rubber 61, the thickness of the rubber material 59 formed on the surface of the base material 56 can be increased. In other words, compared to the case where the rubber material is coated on the surface of the base material 56 by a method other than insert molding, the thickness of the rubber material 59 formed on the surface of the base material 56 of the dampers 55A and 55B can be increased. As a result, the internal loss of the dampers 55A and 55B can be increased.

[0061] Furthermore, because the rubber material 59 of the dampers 55A and 55B is foamed rubber containing air bubbles, the dampers 55A and 55B can be made lighter compared to rubber material that does not contain air bubbles. As a result, the vibration actuator 10 can more easily exhibit the desired vibration characteristics.

[0062] Furthermore, since the magnetic circuit 40 is supported by two dampers 55A and 55B in the case 20, the magnetic circuit 40 can be vibrated in a more stable state compared to the case where the magnetic circuit 40 is supported by a single damper.

[0063] Furthermore, when no electricity flows through the coil 32 and the electrical cables 35 and 36, the dampers 55A and 55B are substantially symmetrical with respect to the virtual plane 20P passing through the center of gravity G. Therefore, compared to the case where the dampers 55A and 55B are asymmetrical with respect to the virtual plane 20P, the vibration actuator 10 can vibrate the magnetic circuit 40 in a stable state.

[0064] Furthermore, since the dampers 55A and 55B have an annular shape centered on the axis 20C, the dampers 55A and 55B can vibrate the magnetic circuit 40 in a stable state.

[0065] Furthermore, when current is supplied to the coil 32, the coil 32 generates heat, and this heat is transferred to the yoke 42. However, the annular recess 45 and the inner circumference end of the damper 55A are fixed with a heat-resistant adhesive, and the annular recess 46 and the inner circumference end of the damper 55B are also fixed with a heat-resistant adhesive. Therefore, even if the yoke 42 becomes hot due to this heat, the dampers 55A and 55B are difficult to separate from the yoke 42.

[0066] Although the present disclosure has been described above based on embodiments, the present disclosure may be modified as appropriate without departing from its essence.

[0067] For example, the present disclosure may be implemented in the form of the first modified example shown in Figure 10. In the first modified example, the dampers 80A and 80B of the vibration actuator 10A have rubber material 59 provided on only one surface in the thickness direction of the base material 56, and the other surface does not have rubber material 59. However, even in the first modified example, a part of the rubber material 59 enters the gap between the threads that make up the base material 56. Furthermore, in the vibration actuator 10A as well, when no electricity is flowing through the coil 32, the pair of dampers 80A and 80B are symmetrical with respect to a virtual plane 20P passing through the center of gravity G. In the vibration actuator 10A as well, the inner circumferential end of the damper 80A is placed over the annular recess 45 of the yoke 42, and the annular recess 45 and the inner circumferential end of the damper 80A are fixed with a heat-resistant adhesive. Furthermore, the inner circumferential end of the damper 80B is placed over the annular recess 46 of the yoke 42, and the annular recess 46 and the inner circumferential end of the damper 80B are fixed with a heat-resistant adhesive. Since the dampers 80A and 80B of the vibration actuator 10A have rubber material 59 provided on only one side in the thickness direction of the base material 56, they are lighter and can be manufactured at a lower cost compared to dampers 55A and 55B.

[0068] The present disclosure may also be implemented in the form of the second modified example shown in Figure 11. In the second modified example, the damper 83A of the vibration actuator 10B has rubber material 59 provided on only one surface in the thickness direction of the base material 56, and not on the other surface. Furthermore, in the second modified example as well, a part of the rubber material 59 enters into the gap between the threads that make up the base material 56. Furthermore, the connecting end 84, which is the inner circumference end of the damper 83A, does not have rubber material 59. In the vibration actuator 10B, the connecting end 84 of the damper 83A is placed over the annular recess 45 of the yoke 42, and the annular recess 45 and the connecting end 84 are fixed with a heat-resistant adhesive. Note that the damper fixed to the annular recess 46 of the yoke 42, which is not shown, is symmetrical to the damper 83A with respect to the virtual plane 20P. That is, this damper has the same structure as the damper 83A. This damper also has its connecting end 84 fixed to the annular recess 46 with a heat-resistant adhesive. In this way, in the vibration actuator 10B, the connecting end 84 made of chemical fibers is fixed to the yoke 42 with adhesive, making it easier to increase the adhesive strength between the damper 80A and the magnetic circuit 40 compared to the vibration actuator 10 in which the rubber material 59 is fixed to the yoke 42 with adhesive.

[0069] The present disclosure may also be implemented in the third modified form shown in Figure 12. In the third modified form, an annular resin material 86 is provided on the outer circumference of the yoke 42 of the vibration actuator 10C, for example, by insert molding. Furthermore, the inner circumference end of damper 80A is fixed to the upper end of the resin material 86 with a heat-resistant adhesive, and the inner circumference end of damper 80B is fixed to the lower end of the resin material 86 with a heat-resistant adhesive. Furthermore, in the vibration actuator 10C as well, when no electricity is flowing through the coil 32, the pair of dampers 80A and 80B are symmetrical with respect to a virtual plane 20P passing through the center of gravity G. Thus, in the vibration actuator 10C, the dampers 80A and 80B are bonded to the resin material 86 instead of the metal yoke 42. Therefore, the adhesive strength of dampers 80A and 80B to the magnetic circuit 40 (resin material 86) in the vibration actuator 10C is higher than the adhesive strength of dampers 55A and 55B to the magnetic circuit 40 in the vibration actuator 10.

[0070] The present disclosure may also be implemented in the form of the fourth modified example shown in Figure 13. In the fourth modified example, the inner circumferential end of a retaining member 90, which has a crank-shaped cross-section, is fixed to the outer circumference of the upper and lower end surfaces of the yoke 42 of the vibration actuator 10D with adhesive. Furthermore, the retaining portion 91, which is the outer circumferential end of each retaining member 90, sandwiches the inner circumferential end of the corresponding dampers 80A and 80B between itself and the annular recesses 45 and 46. Therefore, there is little risk of the dampers 80A and 80B falling off the yoke 42.

[0071] The present disclosure may also be implemented in the form of a fifth modified example shown in Figure 14. In the fifth modified example, through holes 81 are formed at the inner circumferential ends of the dampers 80A and 80B of the vibration actuator 10E, penetrating the dampers 80A and 80B in the thickness direction. Furthermore, a portion of the heat-resistant adhesive 82 provided in the annular recesses 45 and 46 passes through the corresponding through holes 81, and the end 82A of the adhesive 82 opposite to the annular recesses 45 and 46 is solidified on the surface of the base material 56 of the dampers 80A and 80B. Moreover, the diameter (planar shape) of each end 82A is larger than the diameter (planar shape) of the through hole 81. Therefore, there is little risk of the dampers 80A and 80B falling off the yoke 42.

[0072] Alternatively, the inner circumferential end of the damper and the yoke 42 may be mechanically fastened together. For example, female threaded holes may be formed in the bottom surfaces of the annular recesses 45 and 46 of the yoke 42, and a bolt that passes through the inner circumferential end of the damper may be screwed into these female threaded holes to fix the inner circumferential end of the damper to the yoke 42.

[0073] The vibration actuators 10, 10A, 10B, 10C, 10D, and 10E may each have only one damper. In this case, it is preferable to position the damper on the virtual plane 20P.

[0074] The vibration actuator may be equipped with three or more dampers.

[0075] The rubber material 59 may be provided on both sides in the thickness direction of each damper in the second to fifth modified examples. Furthermore, the combination of the base material and the rubber material is not limited to the configuration of the embodiment, and the base material may be placed on both sides in the thickness direction of each damper, with the rubber material 59 provided between the base material 56.

[0076] In the embodiment and each modified example, it is not necessary for a portion of the rubber material 59 to enter the gaps between the threads that make up the base material 56 of the damper.

[0077] The rubber material 59 of the damper in the embodiment and each modified example may be made of a rubber different from foamed rubber.

[0078] The base material 56 of the damper in the embodiment and each of its modifications may be made of a chemical fiber other than aramid, or the base material 56 may be made of cotton. Chemical fibers other than aramid include, for example, polyester.

[0079] The rubber material 59 in the embodiments and each modified example may be a different rubber from EPDM (ethylene propylene rubber), SBR (styrene butadiene rubber), or NBR (nitrile rubber). Furthermore, the rubber material 59 may be a different rubber from foamed rubber.

[0080] Alternatively, the rubber material of the embodiment and each modified example may be coated onto the surface of the base material 56 by a method other than insert molding using a mold. For example, the base material and the rubber material may be bonded together.

[0081] The dampers in the embodiments and their modifications do not have to be annular in shape. For example, instead of an annular damper, the magnetic circuit 40 may be supported by a plurality of dampers that extend radially from the case 20 (yoke 42) connecting the case 20 and the magnetic circuit 40. In this case, it is preferable that the plurality of dampers are provided at equal angular intervals in the circumferential direction centered on the axis 20C. Furthermore, the shape of the damper does not have to be a wave-like shape with uneven surfaces as shown in Figure 6. For example, a flat plate-shaped damper may be formed by insert molding a rubber material into a base material of a planar damper.

[0082] The magnetic circuit 40 of the embodiment and each of its modifications may not include the yoke 42 and pole piece 49, but may include only the magnet 47.

[0083] The disclosure of Japanese Patent Application No. 2024-157560, filed on 11 September 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated herein by reference.

Claims

1. A vibration actuator comprising: a case; a cylindrical voice coil housed in and fixed to the case; a magnetic circuit housed in the case and capable of generating a magnetic field extending to the voice coil, and which reciprocates relative to the case in the axial direction of the voice coil when current flows through the voice coil; and a damper connecting the case and the magnetic circuit so that the magnetic circuit can reciprocate in the axial direction, wherein the damper comprises: a base material made of cloth; and a rubber material integrated with the base material and having greater internal loss than the base material.

2. The vibration actuator according to claim 1, wherein the rubber material is foamed rubber.

3. The vibration actuator according to claim 1 or claim 2, wherein the rubber material is provided on both sides of the base material in the thickness direction.

4. The vibration actuator according to claim 1 or claim 2, wherein a portion of the rubber material is inserted into the gaps between the fibers constituting the cloth.

5. The vibration actuator according to claim 1 or claim 2, wherein the plurality of dampers arranged in the axial direction are connected to the case and the magnetic circuit.

6. The vibration actuator according to claim 5, wherein there are two dampers.

7. The vibration actuator according to claim 6, wherein the two dampers are symmetrical with respect to a virtual plane perpendicular to the axis.

8. The vibration actuator according to claim 1 or claim 2, wherein the damper has an annular shape centered on the axis of the voice coil.

9. The vibration actuator according to claim 1 or claim 2, wherein the rubber material is provided on one surface of the substrate in the thickness direction, excluding the connecting end which is the end on the magnetic circuit side, and the connecting end is bonded to the magnetic circuit.

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