Noise suppression components

Abstract

To provide noise suppression components that can effectively reduce high-frequency noise. [Solution] The noise suppression component comprises a ferrite core formed in a cylindrical shape from Mn-Zn ferrite. In the noise suppression component, the impedance relative permeability at 23°C is 1200 or more at 1 MHz and 500 or more at 10 MHz.

Description

Technical Field

[0001] The present invention relates to a noise countermeasure component.

Background Art

[0002] As a component for reducing noise propagating through a cable connected to an electronic device, a noise countermeasure component having an annularly formed ferrite core is known (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] With the recent increase in speed and capacity of electronic devices, noise has also been shifting to higher frequencies. For this reason, there has been a growing demand for noise countermeasure components that can effectively reduce high-frequency noise, for example, noise of 1 MHz or higher.

[0005] In view of the above circumstances, an object of the present invention is to provide a noise countermeasure component capable of effectively reducing high-frequency noise.

Means for Solving the Problem

[0006] To achieve the above object, a noise countermeasure component according to one embodiment of the present invention includes a ferrite core formed into a cylindrical shape from Mn-Zn based ferrite. In the noise countermeasure component, the impedance relative permeability at 23° C. is 1200 or more at 1 MHz, and 500 or more at 10 MHz.

[0007] In the noise suppression component, the impedance-to-permeability ratio at 125°C may be 1000 or more at 1 MHz and 200 or more at 10 MHz. In the noise suppression component, the rate of change of the impedance relative permeability at 125°C with respect to the impedance relative permeability at 23°C may be 0 to 60% at 1 MHz and -40 to 0% at 10 MHz. The coercivity of the ferrite core at 23°C may be 10 A / m or more and 25 A / m or less. The ferrite core may be divided in the circumferential direction and composed of a plurality of segments, each having a pair of connecting surfaces at both ends in the circumferential direction. The pair of connecting surfaces of the plurality of segments are the product of arithmetic mean roughness Sa (μm) and flatness FL (μm) Sa × FL (μm) 2 ) may be a plane with a value of 12 or less. The pair of connecting surfaces of the plurality of segments are the product of arithmetic mean roughness Sa (μm) and flatness FL (μm) Sa × FL (μm) 2 ) may be a plane with 1 or more sides. The noise suppression component may be used in environments where high-frequency noise of 1 MHz or higher is generated. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a noise suppression component that can effectively reduce high-frequency noise. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a noise suppression component (closed state) according to one embodiment of the present invention. [Figure 2] This is a perspective view of the above noise suppression component (in the open position). [Figure 3] This is a diagram illustrating the method for measuring arithmetic mean roughness Sa (μm). [Figure 4] This is a diagram illustrating the method for measuring flatness FL (μm). [Modes for carrying out the invention]

[0010] [Noise suppression components] The noise suppression component 100 according to one embodiment of the present invention is configured to be particularly effective when used in environments where high-frequency noise of 1 MHz or higher is generated.

[0011] Figures 1 and 2 are perspective views of a noise suppression component 100 according to one embodiment of the present invention. The noise suppression component 100 comprises a ferrite core 10 and a case 20. In the noise suppression component 100, the case 20 houses the ferrite core 10. Figure 1 shows the closed state of the noise suppression component 100 with the case 20 closed. Figure 2 shows the open state of the noise suppression component 100 with the case 20 open.

[0012] The ferrite core 10 is cylindrical and divided in the circumferential direction, and is composed of semi-cylindrical first and second segments 10a and 10b. Each segment 10a and 10b has a pair of connecting surfaces C1 and C2 at both ends in the circumferential direction. The case 20 is composed of a first housing section 20a that houses the first segment 10a and a second housing section 20b that houses the second segment 10b. The case 20 is typically made of a nylon-based resin. However, the material used to form the case is not limited to nylon-based resins, and may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA), polyphenylene sulfide (PPS), silicone resin, or silicone elastomer. Furthermore, the material used to form the case may also be a resin containing fillers such as glass fiber (GF), carbon fiber (CF), or graphite (GP) to improve strength and heat resistance.

[0013] The case 20 includes a hinge portion 21. As shown in FIG. 2, the hinge portion 21 mutually connects the accommodating portions 20a and 20b between the first connection surface C1 of the first segment 10a and the first connection surface C1 of the second segment 10b. Accordingly, the case 20 is configured such that the accommodating portions 20a and 20b can be opened and closed starting from the hinge portion 21 by an operation of moving the second connection surfaces C2 of the respective segments 10a and 10b toward and away from each other.

[0014] The case 20 further includes a lock mechanism 22. The lock mechanism 22 includes a claw portion 22a provided on an outer side of the second connection surface C2 of the first segment 10a in the first accommodating portion 20a, and a groove portion 22b provided on an outer side of the second connection surface C2 of the second segment 10b in the second accommodating portion 20b. The noise suppression component 100 can maintain the closed state in which the case 20 is closed by engaging the claw portion 22a and the groove portion 22b of the lock mechanism 22.

[0015] The noise suppression component 100 is configured such that, in the closed state shown in FIG. 1, close contact between the connection surfaces C1 and C2 of the first segment 10a and the connection surfaces C1 and C2 of the second segment 10b is maintained. That is, in the noise suppression component 100, by closing the case 20 from the open state shown in FIG. 2 to the closed state shown in FIG. 1, the segments 10a and 10b accommodated in the case 20 are integrated to form the cylindrical ferrite core 10.

[0016] The noise suppression component 100 is configured to be capable of effectively reducing high-frequency noise. Specifically, in the noise suppression component 100, the impedance relative permeability at 23° C. is 1200 or more at 1 MHz and 500 or more at 10 MHz, preferably 1400 or more at 1 MHz and 600 or more at 10 MHz. Further, in the noise suppression component 100, the coercive force of the ferrite core 10 at 23° C. is preferably 10 A / m or more and 25 A / m or less, and more preferably 12 A / m or more and 20 A / m or less.

[0017] Further, it is preferable that the noise suppression component 100 has a configuration capable of effectively reducing high-frequency noise even in a high-temperature environment of about 125°C, in order to cope with the increase in heat generation accompanying the higher performance of recent electronic devices (particularly in-vehicle applications). Therefore, in the noise suppression component 100, the impedance relative permeability at 125°C is preferably 1000 or more at 1 MHz and 200 or more at 10 MHz, and more preferably 1200 or more at 1 MHz and 300 or more at 10 MHz.

[0018] Furthermore, in the noise suppression component 100, it is preferable that the performance of reducing high-frequency noise does not change significantly from room temperature to high temperature. Therefore, in the noise suppression component 100, the change rate Δμr(100×(μr1-μr0) / μr0) of the impedance relative permeability μr1 at 125°C with respect to the impedance relative permeability μr0 at 23°C is preferably 0% or more and 60% or less at 1 MHz, and -40% or more and 0% or less at 10 MHz, and more preferably 15% or more and 60% or less at 1 MHz, and -30% or more and 0% or less at 10 MHz.

[0019] In the noise suppression component 100, an appropriate ferrite material for forming the ferrite core 10 is selected so that the above-described impedance relative permeability characteristics can be obtained. Specifically, the ferrite material forming the ferrite core 10 is selected from Mn-Zn ferrites, which are particularly advantageous for reducing noise at high frequencies of 1 MHz or higher. In the noise suppression component 100, the use of Mn-Zn ferrrite enables size reduction of the ferrite core 10. Specifically, for the ferrite core 10 using Mn-Zn ferrite, for example, when the inner diameter is 15 mm, the outer diameter can be reduced by about 20% while ensuring equivalent performance compared to a configuration using Ni-Zn ferrite.

[0020] Furthermore, in the noise suppression component 100, in order to obtain the impedance-to-permeability characteristics described above, it is preferable that the connection surfaces C1 and C2 of each segment 10a and 10b are planes that possess both smoothness and flatness. In this embodiment, the planarity index (μm) is defined as the product of the arithmetic mean roughness Sa (μm) and the flatness FL (μm), Sa × FL, as an index for evaluating the smoothness and flatness of the connection surfaces C1 and C2 together. 2 Use ).

[0021] On each connecting surface C1 and C2 of each segment 10a and 10b, the higher the smoothness, the smaller the arithmetic mean roughness Sa, and the higher the flatness, the smaller the flatness FL; therefore, a smaller planarity index is preferable. Specifically, in the noise suppression component 100, in order to obtain the impedance relative permeability characteristics described above, it is preferable to improve the polishing accuracy so that the planarity index of each connecting surface C1 and C2 of each segment 10a and 10b is 12 or less, and more preferably 9 or less. Furthermore, in the noise suppression component 100, from the viewpoint of reducing manufacturing costs, it is preferable that the planarity index is 1 or more, and more preferably 5 or more. On each connecting surface C1 and C2 of each segment 10a and 10b, the arithmetic mean roughness Sa and flatness FL can be adjusted by polishing conditions, etc.

[0022] In addition, it is preferable that the noise suppression component 100 is configured such that the contact between the connection surfaces C1 and C2 of segments 10a and 10b is not easily impaired even when external forces such as vibration are applied, so that the impedance-to-permeability characteristics described above are well maintained. Therefore, it is preferable that the case 20 is configured such that a biasing force is applied between the connection surfaces C1 and C2 of segments 10a and 10b when the noise suppression component 100 is in the closed state.

[0023] For this purpose, for example, elastic pieces can be provided in the housing sections 20a and 20b of the case 20, respectively, to press against the cylindrical outer surfaces of each segment 10a and 10b of the ferrite core 10 with elastic force when the noise suppression component 100 is in a closed state. In addition, the noise suppression component 100 may use separately prepared elastic members such as coil springs to maintain the airtightness of the connecting surfaces C1 and C2 of segments 10a and 10b.

[0024] The noise suppression component 100 according to this embodiment is not limited to the above configuration. For example, the overall shape of the ferrite core 10 can be cylindrical, and in addition to a true cylindrical shape (the outer shape of the cross section perpendicular to the central axis is a true circular annular shape), it can also be, for example, an elliptical cylindrical shape (the shape of the cross section perpendicular to the central axis is an elliptical annular shape), a square cylindrical shape (the shape of the cross section perpendicular to the central axis is a square annular shape), or a rounded square cylindrical shape (the shape of the cross section perpendicular to the central axis is a rounded square annular shape). Furthermore, the case 20 can be configured to maintain a closed state, and the configuration of the locking mechanism 22 does not have to include a claw portion 22a and a groove portion 22b. Moreover, the case 20 may be configured without a hinge portion 21.

[0025] Furthermore, the noise suppression component 100 may have a configuration without a case 20. In this case, for example, the segments 10a and 10b constituting the ferrite core 10 of the noise suppression component 100 may be integrated by coating with an external coating agent. Examples of external coating agents that can be used to integrate the segments 10a and 10b constituting the ferrite core 10 include epoxy resin.

[0026] Furthermore, in the noise suppression component 100, the ferrite core 10 may be divided into three or more segments. In this case as well, it is preferable that the plane index of any of the connection surfaces C1, C2 of the three or more segments constituting the ferrite core 10 is 12 or less. Alternatively, in the noise suppression component 100, the ferrite core 10 may not be divided into multiple segments, but may be a sintered body molded as a single cylindrical unit.

[0027] [Evaluation Method] In this embodiment, impedance relative permeability, coercivity, arithmetic mean roughness Sa, and flatness FL are measured by the method shown below.

[0028] (Impedance ratio permeability) To measure the impedance relative permeability of a sample of noise suppression component, an impedance analyzer (Keysight "4294A") is used. Specifically, a Φ0.5mm single-strand lead wire (Tanaka Electric Wire Co., Ltd. "H-PVC") is passed through the sample in a single turn, and the measurement is performed using a 16047E fixture. To measure the impedance relative permeability at 125°C, an environmental test machine (ESPEC "SH-221") is used. The lead wire is extended, introduced into the machine from the side, and the lead wire is passed once through the sample placed inside the machine for measurement. Calibration is performed using the lead wire to be used before measurement. A heat-resistant lead wire (Nissei Electric "FN-2-0.3SQ-Aka-10") is used for measurement. As a temperature reference, the measurement value of a thermocouple attached to the sample, recorded by a data logger, is used, rather than the temperature displayed on the environmental test machine.

[0029] (Coercivity) The coercivity of the ferrite core is measured using an automatic coercivity meter (Tokyo Special Steel Co., Ltd. "K-HC1000").

[0030] (Arithmetic mean roughness Sa) The arithmetic mean roughness Sa of the connecting surfaces C1 and C2 of each segment 10a and 10b is measured using a non-contact shape measuring machine (Keyence "VK-X3000") in accordance with ISO 25178. As shown in Figure 3, the arithmetic mean roughness Sa of the connecting surfaces C1 and C2 is measured in the region P enclosed by the dashed line shown in Figure 3, which is located w1 inward from both ends in the axial direction and w2 inward from both ends in the radial direction. w1 is 1 mm and w2 is 1 mm. The arithmetic mean roughness S of each ferrite core is calculated as the average value of the arithmetic mean roughness Sa measured for the four connecting surfaces C1 and C2. For ferrite cores divided into three or more segments, the arithmetic mean roughness Sa is calculated as the average value of the arithmetic mean roughness Sa measured for all connecting surfaces.

[0031] (Flatness FL) The flatness FL of the connecting surfaces C1 and C2 of each segment 10a and 10b is the sum of the absolute values ​​of the maximum and minimum values ​​of the cross-sectional curve measured in accordance with JIS B 0601:2001. However, if the maximum value of the cross-sectional curve includes a noise peak, the maximum peak height Rp of the roughness curve shall be used as the maximum value. Also, if the minimum value of the cross-sectional curve includes a noise peak, that peak shall not be included in the calculation of flatness. For the connecting surfaces C1 and C2, the cross-sectional curve is measured radially using a surface roughness measuring instrument (SURFCOM, 1400G, manufactured by Tokyo Seimitsu Co., Ltd.).

[0032] Details of the measurement locations will be explained using Figure 4. In the configuration shown in Figure 4, the connecting surfaces C1 and C2 are assumed to be rectangular in shape with an axial dimension L of 10 mm. If the dimension L of the connecting surfaces C1 and C2 is greater than 3 mm and less than or equal to 15 mm, the cross-sectional curves are measured at a total of three locations: the upper R1 located w3 inward from one end of the connecting surfaces C1 and C2 in the axial direction, the central R2 in the axial direction of the connecting surfaces C1 and C2, and the lower R3 located w3 inward from the other end of the connecting surfaces C1 and C2 in the axial direction. The flatness FL is then determined from these cross-sectional curves. In this embodiment, w3 is 1 mm. The flatness FL of each connecting surface C1 and C2 is determined as the average value of the flatness FL determined from the three cross-sectional curves. The flatness FL of each ferrite core is determined as the average value of the flatness FL of the four connecting surfaces C1 and C2. Note that the flatness FL of a ferrite core divided into three or more segments is determined as the average value of the flatness FL measured for all connecting surfaces.

[0033] If the dimension L of the connecting surfaces C1 and C2 is greater than 2 mm and less than or equal to 3 mm, the cross-sectional curve is measured at two locations: the upper R1, which is w3 units inward from one end in the axial direction, and the lower R3, which is w3 units inward from the other end in the axial direction. If the dimension L of the connecting surfaces C1 and C2 is 2 mm or less, the cross-sectional curve is measured only at the central part in the axial direction. Furthermore, if the dimension L of the connecting surfaces C1 and C2 is 15 mm or more, additional measurement points are added every 5 mm. In all cases, the flatness FL of each connecting surface C1 and C2 is determined as the average value of the flatness FL determined from all the cross-sectional curves. The flatness FL of each ferrite core is determined as the average value of the flatness FL of the four connecting surfaces C1 and C2. Note that for ferrite cores divided into three or more segments, the flatness FL is determined as the average value of the flatness FL measured for all connecting surfaces.

[0034] Next, we will explain the measurement length of the cross-sectional curve. The radial measurement length y of the connecting surfaces C1 and C2 shall be 4 mm in accordance with JIS B 0601:2001. The cross-sectional curve shall be measured at the radial center of the connecting surfaces C1 and C2. If the radial dimension e of the connecting surfaces C1 and C2 is 8 mm or more, additional measurement points shall be added at 4 mm intervals. In this case, the average value of all measurement points shall be used as the measurement length. If it is not possible to add measurement points at 4 mm intervals, the 4 mm at the radial center shall be measured.

[0035] [Other embodiments] With regard to the embodiments described above, the present invention further discloses the following configurations. <1> It comprises a ferrite core formed in a cylindrical shape from Mn-Zn ferrite, The impedance-to-permeability ratio at 23°C is 1200 or higher at 1 MHz and 500 or higher at 10 MHz. Noise suppression component. <2> <1> The noise suppression components described above, The impedance-to-permeability ratio at 125°C is 1000 or more at 1 MHz and 200 or more at 10 MHz. Noise suppression component. <3> <1> or <2> The noise suppression components described above, The rate of change of the impedance relative permeability at 125°C relative to the impedance relative permeability at 23°C is between 0 and 60% at 1 MHz, and between -40 and 0% at 10 MHz. Noise suppression component. <4> <1> from <3> A noise suppression component described in any one of the following: The coercivity of the ferrite core at 23°C is 10 A / m or more and 25 A / m or less. Noise suppression component. <5> <1> from <4> A noise suppression component described in any one of the following: The ferrite core is divided in the circumferential direction and consists of a plurality of segments, each having a pair of connecting surfaces at both ends in the circumferential direction. Noise suppression component. <6> <5> The noise suppression components described above, The pair of connecting surfaces of the plurality of segments are planes in which the product of the arithmetic mean roughness Sa (μm) and the flatness FL (μm), Sa × FL (μm²), is 12 or less. Noise suppression component. <7> <6> The noise suppression components described above, The pair of connecting surfaces of the plurality of segments are planes in which the product of the arithmetic mean roughness Sa (μm) and flatness FL (μm) Sa × FL (μm²) is 1 or greater. Noise suppression component. <8> <1> from <7> A noise suppression component described in any one of the following: Used in environments where high-frequency noise of 1 MHz or higher is generated. Noise suppression component.

[0036] [Examples and Comparative Examples] (Preparation of samples related to Examples 1-9) In Examples 1-9, samples of noise suppression components were fabricated using a toroidal ferrite core made of Mn-Zn ferrite material, divided into two segments with an outer diameter of 28.5 mm, an inner diameter of 18.0 mm, and a height of 10 mm. In the samples of Examples 1-9, the planar exponents of each segment were varied in various ways.

[0037] (Preparation of samples related to Comparative Examples 1 and 2) In Comparative Example 1, a sample of a noise suppression component was fabricated using a toroidal ferrite core made of Ni-Zn ferrite material, divided into two segments with an outer diameter of 28.5 mm, an inner diameter of 18.0 mm, and a height of 10 mm. In Comparative Example 2, a sample of a noise suppression component was fabricated using a toroidal ferrite core made of a different Ni-Zn ferrite material than that used in Comparative Example 1, divided into two segments with an outer diameter of 28.5 mm, an inner diameter of 18.0 mm, and a height of 10 mm.

[0038] (Sample evaluation) For the samples related to Examples 1-9 and Comparative Examples 1 and 2, the impedance relative permeability at 1 MHz (23°C, 125°C), impedance relative permeability at 10 MHz (23°C, 125°C), rate of change of impedance relative permeability at 1 MHz Δμr, rate of change of impedance relative permeability at 10 MHz Δμr, coercivity at 23°C (A / m), and plane index (μm) were determined according to the method described above. 2 Measurements were taken of the following:

[0039] Table 1 shows the measurement results for samples related to Examples 1-9 and Comparative Examples 1 and 2. In all samples related to Examples 1-9, sufficiently high values ​​were obtained for impedance relative permeability at 1 MHz (23°C, 125°C) and impedance relative permeability at 10 MHz (23°C, 125°C). In particular, in samples related to Examples 1-6, where the planarity index of the connection surface of the segments constituting the ferrite core was 12 or less, the rate of change Δμr of impedance relative permeability was between 0% and 60% at 1 MHz, and between -40% and 0% at 10 MHz.

[0040] On the other hand, in the samples related to Comparative Examples 1 and 2, which used ferrite cores formed from Ni-Zn ferrite, sufficiently high values ​​were not obtained for at least one of the impedance relative permeability at 1 MHz (23°C, 125°C) and the impedance relative permeability at 10 MHz (23°C, 125°C).

[0041] [Table 1] [Explanation of symbols]

[0042] 100: Noise suppression components 10: Ferrite core 10a: First segment 10b: Second segment 20: Case 20a: First containment area 20b: Second containment area 21: Hinge section 22: Locking mechanism 22a: Claw part 22b:Groove C1, C2: Connection surface

Claims

1. It comprises a ferrite core formed in a cylindrical shape from Mn-Zn ferrite, The impedance-to-permeability ratio at 23°C is 1200 or higher at 1 MHz and 500 or higher at 10 MHz. Noise suppression component.

2. A noise suppression component according to claim 1, The impedance-to-permeability ratio at 125°C is 1000 or more at 1 MHz and 200 or more at 10 MHz. Noise suppression component.

3. A noise suppression component according to claim 1, The rate of change of the impedance relative permeability at 125°C relative to the impedance relative permeability at 23°C is between 0 and 60% at 1 MHz, and between -40 and 0% at 10 MHz. Noise suppression component.

4. A noise suppression component according to claim 1, The coercivity of the ferrite core at 23°C is 10 A / m or more and 25 A / m or less. Noise suppression component.

5. A noise suppression component according to any one of claims 1 to 4, The ferrite core is divided in the circumferential direction and consists of a plurality of segments, each having a pair of connecting surfaces at both ends in the circumferential direction. Noise suppression component.

6. A noise suppression component according to claim 5, The pair of connecting surfaces of the plurality of segments are the product of arithmetic mean roughness Sa (μm) and flatness FL (μm) Sa × FL (μm) ２ ) is a plane with a value of 12 or less. Noise suppression component.

7. A noise suppression component according to claim 6, The pair of connecting surfaces of the plurality of segments are the product of arithmetic mean roughness Sa (μm) and flatness FL (μm) Sa × FL (μm) ２ ) is a plane with 1 or more dimensions. Noise suppression component.

8. A noise suppression component according to claim 1, Used in environments where high-frequency noise of 1 MHz or higher is generated. Noise suppression component.

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