Dynamic damper

Abstract

To provide a dynamic damper that can widely accommodate different vibration frequencies and contribute to further miniaturization and cost reduction. [Solution] The device comprises a mounting part 15 attached to the object to be damped 102, a plate member 12 having spring characteristics that extend in the longitudinal direction, a casing body 11 having an internal space that extends in the longitudinal direction and to which the free end of the plate member is fixed, a magnetic fluid 13 containing a magnetic material and sealed in the internal space, a magnetic field generating device 14 positioned in a region adjacent to the casing body and spaced apart from the casing body in a direction intersecting the longitudinal direction, which generates a magnetic field, and a control device 16 that controls the magnetic field generating device. The magnetic field control device controls the magnetic field generating device to generate a magnetic field and variably controls the natural vibration value by displacing the position of the internal space of the magnetic fluid sealed in the internal space in the longitudinal direction.

Description

Technical Field

[0001] This invention relates to a dynamic damper using a magnetic fluid or a magnetorheological fluid.

Background Art

[0002] Conventionally, as a vibration control device for controlling vibrations generated in structures and the like, for example, a vibration control device called a dynamic vibration absorber (DVA) or a dynamic damper is well-known and widely used in general.

[0003] For example, the dynamic vibration absorber disclosed in Japanese Utility Model Publication No. 62-44153 includes two leaf springs with one end fixed and arranged in parallel, a conductive weight held between the free ends of these leaf springs and capable of vibrating together with the leaf springs, a pair of permanent magnets arranged to face each other with a gap provided from the conductive weight and generating a magnetic field in a direction intersecting the vibration direction of the conductive weight, and a magnetic fluid held in the gap between the conductive weight and the permanent magnets.

[0004] With this configuration, in addition to the magnetic damping effect when the conductive weight vibrates in the magnetic field of the pair of permanent magnets, a fluid damping effect utilizing the viscous shear effect acting between the magnetic fluid and the conductive weight is added, so that the overall damping effect can be enhanced.

[0005] Also, for example, the vibration control device disclosed in Japanese Patent Application Laid-Open No. 2004-19741 is a cylinder-type magnetorheological fluid damper, which has a configuration in which the magnetorheological fluid in the fluid chamber is unevenly distributed near both ends of the fluid passage, and permanent magnets with a smaller magnetic force than the electromagnet are arranged on both end faces of the piston, and when the electromagnet generates a magnetic force, the inflow of the magnetorheological fluid into the fluid passage is allowed.

[0006] For example, the vibration damping device disclosed in Japanese Patent Publication No. 2016-211696 is a damper having a cylindrical housing, comprising a vibration damping actuator interposed between the radiator and the vehicle body, and a connecting member that elastically connects the vehicle body and the engine. The vibration damping actuator consists of a variable elastic modulus member whose elastic modulus is variable according to the strength of the applied magnetic field. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Utility Model Publication No. 62-44153 [Patent Document 2] Japanese Patent Publication No. 2004-19741 [Patent Document 3] Japanese Patent Publication No. 2016-211696 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in conventional vibration damping devices disclosed in the above-mentioned Japanese Utility Model Publication No. 62-44153, Japanese Patent Publication No. 2004-19741, and Japanese Patent Publication No. 2016-211696, the frequency is set according to the vibration eigenvalue of the object. Therefore, if there are multiple target eigenvalues, a device corresponding to each of the various eigenvalues ​​becomes necessary. This leads to problems such as the increasing size and cost of the devices.

[0009] The present invention aims to provide a dynamic damper that can widely accommodate different vibration frequencies and contribute to further miniaturization and cost reduction. [Means for solving the problem]

[0010] To achieve the above objective, a dynamic damper according to one aspect of the present invention comprises: a mounting portion attached to an object to be damped; a plate member having longitudinally extending spring characteristics; a casing body having an internal space extending in the longitudinal direction and to which the free end of the plate member is fixed; a magnetic fluid containing a magnetic material and sealed in the internal space; a magnetic field generating device positioned in a region adjacent to the casing body and spaced apart from the casing body in a direction intersecting the longitudinal direction, and generating a magnetic field; and a control device for controlling the magnetic field generating device. The magnetic field control device controls the magnetic field generating device to generate a magnetic field and variably controls the natural vibration value by displacing the position of the magnetic fluid sealed in the internal space in the longitudinal direction. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a dynamic damper that can widely accommodate different vibration frequencies and contribute to further miniaturization and cost reduction. [Brief explanation of the drawing]

[0012] [Figure 1] A plan view of the dynamic damper of the first embodiment of the present invention, as seen from the top side. [Figure 2] Cross-sectional view along line [2]-[2] in Figure 1, [Figure 3] Figure 1 shows the action of the dynamic damper, and Figure 2 is a cross-sectional view showing the state after the magnetic fluid has been moved from the state shown in Figure 2. [Figure 4] A cross-sectional view showing the schematic configuration of a dynamic damper according to a second embodiment of the present invention. [Figure 5] Figure 4 is a cross-sectional view showing the state of the dynamic damper after it has been displaced from its original state to another state. [Figure 6] A schematic diagram showing the dynamic damper of the first and second embodiments of the present invention applied to a disc brake system. [Modes for carrying out the invention]

[0013] The present invention will be described below with reference to the illustrated embodiments. Each drawing used in the following description is shown schematically. Therefore, in each of these drawings, each component is shown in a size that can be recognized on the drawing. For this reason, the dimensional relationships and scales of each member on the drawing may be shown differently for each component. The present invention is not limited only to the illustrated forms with respect to the quantity, shape, ratio of size, relative positional relationship, etc. of each component described in each drawing.

[0014] FIG. 1, FIG. 2, and FIG. 3 are views showing a dynamic damper according to a first embodiment of the present invention. Among these, FIG. 1 is a plan view of the dynamic damper according to the first embodiment of the present invention as viewed from the upper surface side. FIG. 2 is a cross-sectional view taken along line [2]-[2] of FIG. 1. FIG. 3 shows the operation of the dynamic damper of the present embodiment and shows the state after moving the magnetic fluid from the state of FIG. 2.

[0015] The dynamic damper 1 according to the first embodiment of the present invention is configured to include a casing body 11, a leaf spring 12, a magnetic fluid 13, a magnetic field generating device 14, a mounting portion 15, a magnetic field control device 16, and the like as shown in the figure.

[0016] The mounting portion 15 is a component portion for attaching the dynamic damper 1 to a structure to be vibration-damped (hereinafter referred to as a vibration-damping object). Further, this mounting portion 15 is a fixing portion for fixing the leaf spring 12.

[0017] The leaf spring 12 is a plate member that extends in the longitudinal direction and has spring characteristics. The base end of the leaf spring 12 is fixed to the mounting portion 15. The free end of the leaf spring 12 is provided so as to be freely vibratable in a direction intersecting the longitudinal direction. Thereby, the leaf spring 12 is a cantilever-like member.

[0018] Note that the leaf spring 12 is illustrated in a form that extends radially outward in the radial direction from positions facing each other around the attachment portion 15, but it is not limited to this form. For example, for a pair of leaf springs 12 arranged to face each other around the attachment portion 15, by arranging another pair of leaf springs 12 in a direction orthogonal to the direction around the attachment portion 15, a form can be adopted in which two pairs of leaf springs 12 are arranged in a cross shape as a whole.

[0019] The casing body 11 has an internal space extending in the longitudinal direction. The free end of the leaf spring 12 is fixed to the casing body 11. Here, the leaf spring 12 is arranged to penetrate along the longitudinal direction in the internal space of the casing body 11. With this configuration, a plurality of gaps 11a are formed between the inner wall surface of the casing body 11 and the surface of the leaf spring 12. And a part of the plurality of gaps 11a is filled with the magnetic fluid 13.

[0020] The magnetic fluid 13 is a fluid containing a magnetic substance such as ferromagnetic fine particles. The magnetic fluid 13 is enclosed in a partial region inside the internal space of the casing body 11. In this case, as described above, the magnetic fluid 13 is enclosed so as to occupy a part of the plurality of gaps 11a. With this configuration, the magnetic fluid 13 enclosed in the plurality of gaps 11a is movable in the direction along the longitudinal direction in the gaps 11a (the direction along the arrow S in FIG. 1).

[0021] The magnetic field generating device 14 is a device that generates a magnetic field by passing an electric current. The magnetic field generating device 14 is arranged in a region adjacent to the casing body 11. The magnetic field generating device 14 is arranged, for example, at a position separated in a direction intersecting the longitudinal direction of the leaf spring 12. By the magnetic field generated from the magnetic field generating device 14 acting on the magnetic fluid 13, the position control of the magnetic fluid 13 is performed.

[0022] The magnetic field control device 16 controls the generation of a magnetic field from the magnetic field generator 14 by controlling the current flowing through the magnetic field generator 14. By controlling the magnetic field generated by the magnetic field generator 14, the magnetic field control device 16 arbitrarily displaces the longitudinal position of the magnetic fluid 13 within the internal space (air gap 11a) of the casing body 11. This allows for variable control of the natural vibration value of the dynamic damper 1.

[0023] Furthermore, all or part of the magnetic field control device 16 is composed of a processor including hardware. Here, the processor is composed of a well-known configuration including, for example, a central processing unit (CPU), RAM (Random Access Memory), ROM (Read Only Memory), non-volatile memory, non-volatile storage, and a non-transitory computer-readable medium, as well as peripheral devices.

[0024] ROM, non-volatile memory, and non-volatile storage devices pre-store software programs executed by the CPU, as well as fixed data such as data tables. The CPU reads the software programs stored in the ROM, loads them into RAM, and executes them. The magnetic field control device 16 functions when these software programs appropriately refer to various data.

[0025] Furthermore, the processor may be composed of semiconductor chips such as FPGAs (Field Programmable Gate Arrays). The magnetic field control device 16 may also be composed of electronic circuits.

[0026] Furthermore, the software program may be recorded in whole or in part as a computer program product on portable disc media such as flexible disks, CD-ROMs, and DVD-ROMs, or on non-transitory computer-readable media such as card-type memory, HDDs (Hard Disk Drives), and SSDs (Solid State Drives).

[0027] In the dynamic damper 1 of the first embodiment configured as described above, the magnetic field generator 14 is controlled by the magnetic field control device 16 to control the position of the magnetic fluid 13 in the longitudinal direction (direction of arrow S) within the air gap 11a.

[0028] For example, the state shown in Figure 2 represents a state in which the magnetic fluid 13 is positioned closest to the base end within the internal space (void 11a).

[0029] Furthermore, for example, the state shown in Figure 3 represents a state in which the magnetic fluid 13 has moved in the direction of arrow S1 from the state shown in Figure 2 within the internal space (air gap 11a) and is positioned at the position closest to the tip.

[0030] Thus, the natural vibration values ​​can be made different when the magnetic fluid 13 is in the position shown in Figure 2 compared to when it is in the position shown in Figure 3.

[0031] Therefore, according to the dynamic damper 1 of the first embodiment described above, the natural vibration value of the dynamic damper 1 can be variably controlled by variably controlling the position of the magnetic fluid 13 in the longitudinal direction (direction along arrow S) within the internal space (air gap 11a) of the casing body 11 in accordance with the vibration of the object to be damped. As a result, according to the first embodiment described above, a more effective and appropriate damping effect can be obtained.

[0032] The dynamic damper of the second embodiment of the present invention, shown below, has a configuration that allows for variable control of the position of the magnetic fluid in response to the vibration of the object to be damped, as well as a configuration that allows for variable control of the fluid mass and viscosity stiffness of the magnetic fluid. For this purpose, in the second embodiment of the present invention, a magnetic viscous fluid 13A is used instead of the magnetic fluid 13 in the first embodiment described above. Here, the magnetic viscous fluid 13A is a magnetic fluid whose viscosity stiffness can be variably controlled by applying an external magnetic field.

[0033] Figures 4 and 5 are cross-sectional views showing the schematic configuration of a dynamic damper according to a second embodiment of the present invention (corresponding to Figure 2). Figure 4 shows one state of the dynamic damper of this embodiment, and Figure 5 shows another state of the same dynamic damper.

[0034] The configuration of the second embodiment is basically the same as that of the first embodiment described above. The differences in the second embodiment are that a magnetic viscous fluid 13A is used instead of the magnetic fluid 13, and that a configuration is provided to movably house the magnetic viscous fluid 13A. Therefore, in the following description, the different configuration will be described in detail, and the configuration that is the same as that of the first embodiment described above will not be described in detail.

[0035] The dynamic damper 1A of the second embodiment is composed of a casing body 11A, a leaf spring 12, a magnetic viscous fluid 13A, a magnetic field generator 14, a mounting part 15A, a magnetic field control device 16, a mass 17, and the like.

[0036] In the second embodiment, the mounting portion 15A is a fixing portion that secures the casing body 11A and the leaf spring 12, and also has a housing portion 15a that houses the magnetic viscous fluid 13A. For this purpose, the mounting portion 15A is formed hollow and has a housing portion 15a formed inside. This housing portion 15a is in communication with the air gap 11Aa in the internal space of the casing body 11A. With this configuration, the magnetic viscous fluid 13A housed in the housing portion 15a flows out from the housing portion 15a into the air gap 11Aa in a predetermined amount in response to the magnetic field generated from the magnetic field generator 14.

[0037] The casing body 11A has an internal space that extends longitudinally from the mounting portion 15A. A leaf spring 12 is positioned through the internal space of the casing body 11A. As a result, a plurality of voids 11Aa are formed between the inner wall surface of the casing body 11A and the surface of the leaf spring 12. In this embodiment, these plurality of voids 11Aa are formed as a continuous space from the mounting base end of the mounting portion 15A to the front end of the internal space. These plurality of voids 11Aa are in communication with the housing portion 15a and allow the inflow of the magnetic viscous fluid 13A from the housing portion 15a. The free end of the leaf spring 12 protrudes outward from the casing body 11A.

[0038] The leaf spring 12 penetrates the internal space of the casing body 11A, and its base end is fixed to the mounting portion 15A. Mass objects 17 are placed at both ends of the free end of the leaf spring 12 (the tip positions of the free ends furthest from the mounting portion 15A).

[0039] The magnetic viscous fluid 13A is a fluid containing magnetic materials such as ferromagnetic fine particles, similar to the magnetic fluid 13 in the first embodiment described above. In the second embodiment, the magnetic viscous fluid 13A is a magnetic fluid whose viscosity and stiffness can be variably controlled by applying an external magnetic field. The magnetic viscous fluid 13A can increase its stress and viscosity according to the strength of the applied magnetic field (the strength of the current flowing from the magnetic field generator 14), thereby enabling variable control to semi-solidify the fluid. The magnetic viscous fluid 13A is sealed inside the housing portion 15a of the mounting portion 15 and the internal space (gap 11Aa) of the casing body 11. With this configuration, the magnetic viscous fluid 13A is movable from the housing portion 15a within the gap 11Aa in the direction along arrow S2 in Figure 4. The other configurations are substantially the same as those of the first embodiment described above.

[0040] In the dynamic damper 1A of the second embodiment configured as described above, the magnetic field control device 16 controls the magnetic field generator 14, thereby controlling the position, fluid mass, and viscosity stiffness of the magnetic viscous fluid 13A in the gap 11Aa from the housing section 15a.

[0041] For example, the state shown in Figure 4 represents a state in which the magnetic viscous fluid 13A is located in the region near the base end indicated by the symbol [A] in the figure within the air gap 11Aa, and is semi-fixed in that region. In this state, the spring constant of the leaf spring 12 decreases and is set to a low natural vibration value.

[0042] Furthermore, for example, the state shown in Figure 5 represents a state in which the magnetic viscous fluid 13A is located in the region indicated by the symbol [B] in the air gap 11Aa and is semi-fixed in that region. In this state, the spring constant of the leaf spring 12 increases and is set to a higher natural vibration value than in the state shown in Figure 4.

[0043] Thus, the natural vibration values ​​can be made different when the magnetic viscous fluid 13A is in the region shown in Figure 4 compared to when it is in the region shown in Figure 5.

[0044] Therefore, according to the dynamic damper 1A of the second embodiment described above, the natural vibration value of the dynamic damper 1A can be variably controlled by variably controlling the arrangement area of ​​the magnetic viscous fluid 13A in the direction along arrow S2 within the internal space (air gap 11Aa) of the housing 15a and the casing body 11A in accordance with the vibration of the object to be damped. As a result, a more effective and appropriate damping effect can be obtained even in the second embodiment described above.

[0045] The dynamic dampers 1 and 1A of the first and second embodiments, configured as described above, can contribute to suppressing so-called brake noise and the like caused by vibration in a disc brake system 100, for example, by being mounted on the outer surface of the caliper device 102 in a disc brake system 100 consisting of a brake rotor 101 and a caliper device 102, as shown in Figure 6.

[0046] In general, brake devices such as the 100 generate vibrations that vary depending on the operating environment, such as the ambient temperature and the temperature of the components themselves, as well as during forward or reverse driving. These vibrations can cause so-called brake squeal and other noises.

[0047] Therefore, by using the dynamic dampers 1,1A of this embodiment to perform variable control of the natural vibration value in response to the vibration of the object to be damped (in this case, the brake device 100 is used as an example), brake noise and the like can be suppressed more effectively.

[0048] The dynamic dampers 1 and 1A exemplified in each embodiment of the present invention are not limited to the brake device 100 described above, but can also be applied to other vibration-generating components, such as steering devices and in-vehicle seat devices, and similarly, effective vibration damping effects can be obtained in these devices as well.

[0049] The present invention is not limited to the embodiments described above, and various modifications and applications can be implemented without departing from the spirit of the invention. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of the multiple constituent elements disclosed. For example, if the problem that the invention aims to solve can be solved and the effects of the invention can be obtained even if some constituent elements are deleted from all the constituent elements shown in one embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. Furthermore, constituent elements from different embodiments may be combined as appropriate. This invention is not limited by any particular embodiment other than being limited by the appended claims. [Explanation of symbols]

[0050] 1.1A…Dynamic damper 11,11A…Casing body 11a,11Aa...Void 12…Leaf spring 13...Magnetic fluid 13A…Magnetorheological fluid 14…Magnetic field generator 15, 15A… Mounting part 15a... Containment area 16… Magnetic field control device 17...mass object 100… Disc brake system 101...Brake rotor 102... Caliper device

Claims

1. Mounting part that attaches to the object to be damped, A plate member having spring properties that extend in the longitudinal direction, A casing body having an internal space extending in the longitudinal direction and to which the free end of the plate member is fixed, A magnetic fluid containing a magnetic material is sealed within the internal space, A magnetic field generating device is provided, which is located in a region adjacent to the casing body and spaced apart from the casing body in a direction intersecting the longitudinal direction, and generates a magnetic field. A control device for controlling the magnetic field generating device, It is equipped with, The magnetic field control device is a dynamic damper characterized by controlling the magnetic field generator to generate a magnetic field and thereby variably controlling the natural vibration value by displacing the position of the magnetic fluid sealed in the internal space in the longitudinal direction of the internal space.

2. The aforementioned plate member is The base end of the cantilevered beam-like member is fixed to the aforementioned mounting portion, and the free end is provided to vibrate freely in a direction intersecting the longitudinal direction. The dynamic damper according to feature 1.

3. The casing body is such that the plate member is arranged to penetrate the internal space in the longitudinal direction, and a gap is formed between the inner wall surface of the casing body and the plate member. The dynamic damper according to claim 1, characterized in that the magnetic fluid is sealed in a portion of the void.

4. The dynamic damper according to claim 1, further characterized in that the plate member has a mass provided at the tip of the free end which is furthest from the mounting portion.

5. The dynamic damper according to claim 1, characterized in that the magnetic fluid is a magnetoviscous fluid.

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