JP2012005029A - Magnetic body for filter and communication connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic body for a filter which can suppress a variation in a high frequency component removal effect due to temperature change.SOLUTION: A magnetic body for a filter is provided with a magnetic member and a stress generating member which is integrally installed with the magnetic member and whose coefficient of thermal expansion is different from the coefficient of thermal expansion of the magnetic member. At a temperature change, the stress generating member generates a stress in the magnetic member and suppresses a variation in a permeability so that a variation in a high frequency component removal may be suppressed.

Description

  The present invention relates to a filter magnetic body and a communication connector.

  2. Description of the Related Art Conventionally, in a connector that connects devices of a communication network such as an in-vehicle LAN, a connector containing ferrite as a filter around a bus bar (bus terminal) is used in order to remove high-frequency component noise of a transmission signal.

JP 2008-159111 A

  However, the ferrite used as a filter has the property that the magnetic permeability changes with temperature. For this reason, the effect of removing high-frequency components by ferrite also varies depending on temperature, and noise removal may not be performed satisfactorily.

  Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a magnetic body for a filter and a communication connector that can suppress a change in the effect of removing a high-frequency component with respect to a change in temperature.

  In order to solve the above problems, the present invention provides a magnetic member for a filter comprising a magnetic member and a stress generating member attached integrally with the magnetic member and having a coefficient of thermal expansion different from that of the magnetic member. To do.

  A ferrite core used as a magnetic body for a filter exhibits characteristics that the magnetic permeability is small when the ambient temperature is low, and the magnetic permeability is large when the ambient temperature is high. For this reason, the impedance characteristics of the ferrite core are low at low temperatures (low attenuation of high frequency components) and high (high attenuation of high frequency components) at high temperatures, and variations in attenuation effects of high frequency components occur due to temperature changes. On the other hand, the magnetic body for a filter of the present invention includes a magnetic member and a stress generating member attached integrally with the magnetic member and having a thermal expansion coefficient different from the thermal expansion coefficient of the magnetic member. When the permeability and impedance of a ferrite core used as a filter magnetic body increase as the temperature rises, the high frequency component may be excessively attenuated and waveform dullness may occur, but in the filter magnetic body of the present invention, The stress generating member is thermally expanded to generate stress inside the magnetic member, thereby suppressing an increase in magnetic permeability and impedance, reducing the variation width of the attenuation effect of the high frequency component due to the temperature change, and reducing the high frequency component. It becomes possible to suppress a change in the removal effect.

  In the filter magnetic body of the present invention, the thermal expansion coefficient of the stress generating member is preferably larger than the thermal expansion coefficient of the magnetic member. If the coefficient of thermal expansion of the stress generating member is larger than the coefficient of thermal expansion of the magnetic member, the stress generating member thermally expands when the temperature rises, generating stress inside the magnetic member. Thereby, the raise of the magnetic permeability and impedance as a magnetic body can be suppressed, and it becomes possible to suppress the change of the high frequency component removal effect with respect to a temperature change.

  Moreover, in the magnetic body for filters of this invention, it is preferable that the stress generation member is attached in the magnetic member. When the stress generating member is attached in the magnetic member, for example, it is easier to integrate the magnetic member and the stress generating member as a magnetic body for the filter than to join the surfaces with each other, and the magnetic member can be formed with a smaller amount of the stress generating member. It is also possible to generate stress in the interior of the.

  Furthermore, this invention provides the communication connector provided with the said magnetic body for a filter in a bus terminal part. Since the communication connector including the filter magnetic body in the bus terminal portion can suppress the change in the high-frequency component removal effect with respect to the temperature change, the reliability of the data communication is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the magnetic body for filters and communication connector which can suppress the change of the high frequency component removal effect with respect to a temperature change can be provided.

It is a schematic block diagram which shows the structure of the magnetic body for filters which concerns on 1st embodiment of this invention. It is a schematic block diagram which shows the structure by which the magnetic body for filters which concerns on 1st embodiment of this invention was mounted | worn with the bus terminal part. It is sectional drawing at the time of the low temperature of the magnetic body for filters which concerns on 1st embodiment of this invention. It is sectional drawing at the time of the high temperature of the magnetic body for filters which concerns on 1st embodiment of this invention. It is a figure which shows the relationship between the temperature of a ferrite core, and a magnetic permeability. It is a figure which shows the relationship between the temperature of a ferrite core, and an impedance. It is a figure which shows the relationship between the stress added to a ferrite core, and an impedance. It is a figure which shows the fall rate of the magnetic permeability with respect to the stress added to a ferrite core. It is a figure which shows the relationship between the temperature of a ferrite core, and an impedance fall rate. It is a figure which compares and shows the relationship of the temperature and impedance of the magnetic body for filters of 1st embodiment of this invention, and a prior art example (only a ferrite core). It is a schematic diagram which shows the magnetic body for filter (attached to a bus terminal part) and the impedance Z. It is a figure which shows the 1st process of accommodating the magnetic body for filters which concerns on 1st embodiment of this invention in a housing. It is a figure which shows the 2nd process of accommodating the magnetic body for filters which concerns on 1st embodiment of this invention in a housing. It is a figure which shows the 3rd process of accommodating the magnetic body for filters which concerns on 1st embodiment of this invention in a housing. It is a figure which shows the example which bakes and joins a magnetic member and a stress generation member. It is a figure which shows the 1st process of the manufacturing method in the magnetic body for filters which concerns on 2nd embodiment of this invention. It is a figure which shows the 2nd process of the manufacturing method in the magnetic body for filters which concerns on 2nd embodiment of this invention. (A) And (b) is a figure which shows the stress generation | occurrence | production in the magnetic body for filters which concerns on 2nd embodiment of this invention.

  Embodiments of the present invention will be described below. In the description of the drawings, the same reference numerals are used for the same elements, and duplicate descriptions are omitted.

(First embodiment)
FIG. 1 is a schematic configuration diagram showing a configuration of a filter magnetic body 1 according to the first embodiment of the present invention. The filter magnetic body 1 (hereinafter sometimes referred to as a magnetic body) includes a magnetic member 2 and a stress generating member 3, and the surfaces of the magnetic member 2 and the stress generating member 3 are joined to each other and formed integrally. .

  The magnetic member 2 has the property of removing noise components at high frequencies. For example, any material may be used as long as it has a high magnetic permeability so that magnetic flux generated by a magnetic field generated in a signal current or the like is converged and consumed as heat energy. As a result, it is possible to remove noise generated when a part of the current energy is emitted from the magnetic field as radio waves.

  As the magnetic member 2, it is preferable to use a ferrite core that has high magnetic permeability and exhibits high impedance characteristics in a high frequency region. The ferrite core can remove noise by converging a magnetic flux generated by a magnetic field generated in a signal current or the like and consuming it as thermal energy by its magnetic permeability. As the ferrite core, for example, a nickel / zinc-based or manganese / zinc-based ferrite core can be used according to a frequency used as a signal.

  The stress generating member 3 is integrally attached to the magnetic member 2 and has a thermal expansion coefficient different from the thermal expansion coefficient of the magnetic member 2. For this reason, since the stress generating member 3 thermally expands at a rate different from that of the magnetic member 2 when the temperature changes, it is possible to generate stress inside the integrated magnetic member 2 and suppress increase in magnetic permeability and impedance. It is possible to reduce the variation width of the high-frequency component attenuation effect due to the temperature change and suppress the change in the high-frequency component removal effect. If the difference between the two thermal expansion coefficients of the stress generating member 3 and the magnetic member 2 is too large, for example, the magnetic member 2 is cracked, and the integrity and function of the filter magnetic body 1 are impaired. Therefore, the difference between the two coefficients of thermal expansion is such that the integrity and function of the filter magnetic body 1 are not impaired.

  The thermal expansion coefficient of the stress generating member 3 is preferably larger than the thermal expansion coefficient of the magnetic member 2. When the coefficient of thermal expansion of the stress generating member 3 is large, for example, the stress generating member 3 expands more thermally than the magnetic member 2 when the temperature rises, so that stress (for example, tensile stress) is generated inside the integrated magnetic member 2. Can be generated.

  Further, the thermal expansion coefficient of the stress generating member 3 may be smaller than the thermal expansion coefficient of the magnetic member 2. When the coefficient of thermal expansion of the stress generating member 3 is smaller than that of the magnetic member 2, for example, the stress generating member 3 does not thermally expand more than the magnetic member 2 when the temperature rises. It will not be possible to expand to the range. For this reason, stress (for example, compressive stress) can be generated inside the magnetic member 2.

  When the magnetic member 2 is a ferrite core, the stress generating member 3 is preferably a ferrite core having a thermal expansion coefficient different from the thermal expansion coefficient of the magnetic member 2, more preferably from the thermal expansion coefficient of the magnetic member 2. It is a ferrite core having a large expansion coefficient. Further, the stress generating member 3 may be a ferrite core having an expansion coefficient smaller than that of the magnetic member 2.

  FIG. 2 is a schematic configuration diagram showing a configuration in which the filter magnetic body 1 is mounted on the bus terminal portion 5. In the present embodiment, it is preferable that the filter magnetic body 1 includes two through holes 4. Moreover, it is preferable that the two bus terminal parts 5 are inserted in these two through-holes 4, and the magnetic body 1 for a filter is hold | maintained as a filter of a communication connector. The filter magnetic body 1 can remove high-frequency components of the signal current in the two bus terminal portions 5. When the connector is a differential transmission system, the two bus terminal portions 5 are + and − terminals.

  FIG. 3 is a cross-sectional view of the filter magnetic body at a low temperature. At a low temperature, the magnetic member 2 and the stress generating member 3 do not thermally expand and generate almost no stress. On the other hand, as shown in FIG. 4, the magnetic member 2 and the stress generating member 3 are expanded by heat at a high temperature. However, when the thermal expansion coefficient of the stress generating member 3 is larger than that of the magnetic member 2, It expands greatly. Therefore, the magnetic member 2 joined integrally with the stress generating member 3 expands together with the stress generating member 3 even though the coefficient of thermal expansion is smaller than that of the stress generating member 3, and stress (for example, tensile stress) is contained therein. ) Will occur. When stress is generated in the magnetic member 2 as described above, it is possible to suppress an increase in the magnetic permeability and impedance of the filter magnetic body 1, and to suppress a high-frequency component from being excessively attenuated to cause waveform dullness, It is possible to reduce the variation width of the high-frequency component attenuation effect due to the change and suppress the change in the high-frequency component removal effect.

  FIG. 5 shows the relationship between the temperature of the ferrite core and the magnetic permeability. As shown in FIG. 5, the permeability (μ) of the ferrite core is low when the temperature is low, and the magnetic permeability increases as the temperature increases.

Further, as shown in FIG. 6, the impedance is low when the temperature is low, as shown in FIG. 6, while the impedance is high when the temperature is high.
Z = k · μ ₀ · μ ”· ω + jk · μ ₀ · μ '· ω (1)
(Z: impedance, μ ₀ : vacuum permeability (= 4 · 10 ⁻⁷ ), ω: 2πf (f: frequency), k: coefficient depending on ferrite shape, j: imaginary unit)

  FIG. 7 shows the relationship between the stress applied to the ferrite core and the impedance Z. 6 and 7 show that the stress is not applied when the temperature is low, and the higher the temperature, the stronger the stress, so that the fluctuation of impedance due to temperature can be suppressed.

In the filter magnetic body 1, the stress generated in the magnetic member 2 (ferrite core) is expressed by the following formula (2), and is proportional to the temperature difference from the reference temperature.
σ = (α2−α1) (T−T ₀ ) · E / 2 (2)
(Σ: stress, α1: ferrite core linear expansion coefficient, α2: stress generating member linear expansion coefficient, E: longitudinal elastic modulus, T: temperature, T ₀ : reference temperature (temperature at which stress = 0))

  FIG. 8 is a diagram showing a decrease rate of magnetic permeability with respect to stress applied to the ferrite core. As shown in FIG. 8, the magnetic permeability decreases as the stress is applied to the magnetic member 2 that is a ferrite core. Further, as described above, the relationship between the impedance Z proportional to the magnetic permeability and the stress is the same as in FIG.

  FIG. 9 is a diagram showing the relationship between the temperature of the ferrite core and the impedance reduction rate, and shows the characteristics obtained from the relationship between the stress and impedance Z shown in FIG. 7 and the relationship between the stress and temperature shown in the above equation (2). FIG. 10 is a diagram comparing the relationship between temperature and impedance of the filter magnetic body according to the first embodiment and the conventional example (only the ferrite core), and the relationship between the temperature and impedance shown in FIG. This is obtained from the product of the relationship between temperature and impedance reduction rate shown in FIG. As shown in FIG. 10, the filter magnetic body (a) according to the first embodiment can generate stress inside the integrated magnetic member because the stress generating member thermally expands. Since the increase in magnetic susceptibility and impedance is suppressed, the variation width of the high-frequency component attenuation effect due to temperature change can be reduced as compared with the conventional example (b). For this reason, it is not necessary to consider the variation in the attenuation effect of the high frequency component due to the temperature change, and the degree of freedom in designing the filter magnetic body and the communication connector is increased. FIG. 11 shows the filter magnetic body 1 mounted on the bus terminal portion 5 and the impedance Z.

  FIG. 12 is a view showing a first step of housing the filter magnetic body according to the first embodiment of the present invention in the housing. As shown in FIG. 12, the filter magnetic body 1 including the magnetic member 2 and the stress generating member 3 is prepared so that the two bus terminal portions 5 are inserted into the two through holes 4. Next, as in the second step shown in FIG. 13, the filter magnetic body 1 is attached to the base portion of the bus terminal portion 5. Further, as in the third step shown in FIG. 14, the housing 15 for housing the filter magnetic body 1 attached to the bus terminal portion 5 is covered, and the communication connector 20 is formed.

  FIG. 15 is a diagram illustrating an example in which the magnetic member 2 and the stress generating member 3 are baked and joined. As shown in FIG. 15, when the magnetic member 2 and the stress generating member 3 are baked and joined and integrally formed, for example, the magnetic member 2 and the stress generating member 3 have two types of ferrite having different thermal expansion coefficients. If it is, it is preferable because it is a similar material, and it is easy to firmly bond by firing, and because it is a similar material, volume efficiency is better than using other materials.

(Second Embodiment)
FIG. 16 is a diagram illustrating a first step of a manufacturing method for a filter magnetic body according to the second embodiment of the present invention. In the filter magnetic body 1 according to the second embodiment, as shown in FIG. 16, the magnetic member 2 is penetrated to fill or press-fit the stress generating member 3 around the two through holes 4 provided in advance. It differs from the filter magnetic body according to the first embodiment in that the hole 6 is provided. The stress generating member 3 filled or press-fitted into the through hole 6 is prepared so as to match the shape of the through hole 6. Next, as in the second step shown in FIG. 17, the stress generating member 3 is filled or press-fitted into the through hole 6 of the magnetic member 2. Thereby, the stress generating member 3 is integrally formed in the magnetic member and becomes the filter magnetic body 1. As described above, filling or press-fitting the stress generating member 3 into the magnetic member 2 is performed by joining the magnetic member 2 and the stress generating member 3 together by surfaces like the filter magnetic body of the first embodiment. It is preferable in that it can be integrally formed more easily than in the case of forming the magnetic member 2 and stress can be generated inside the magnetic member 2 with a smaller amount of the stress generating member 3.

  FIGS. 18A and 18B are views showing stress generation in the filter magnetic body according to the second embodiment of the present invention. As shown in FIGS. 18A and 18B, the stress generating member 3 filled or press-fitted inside the magnetic member 2 is thermally expanded when the ambient temperature is increased, but the coefficient of thermal expansion is the heat of the magnetic member 2. When it is larger than the expansion coefficient, stress (for example, compressive stress) is generated in the magnetic member 2 around the stress generating member 3.

  The above description is an explanation of the embodiment of the present invention, and does not limit the present invention, and various modifications can be easily implemented. For example, in FIG. 1 and the like, the filter magnetic body 1 has a configuration in which the stress generating member 3 is provided on the upper surface side of the magnetic member 2, but the stress generating member 3 may be provided on the lower surface side of the magnetic member 2. Good.

  In FIG. 15, the magnetic member 2 and the stress generating member 3 are bonded by baking, but the magnetic member 2 and the stress generating member 3 are bonded by an adhesive so long as the function as the filter magnetic body 1 is not impaired. And may be integrally formed.

  DESCRIPTION OF SYMBOLS 1 ... Magnetic body for filters, 2 ... Magnetic member, 3 ... Stress generating member, 4 ... Two through-holes, 5 ... Bus terminal part, 6 ... Through for filling or press fit Hole, 10 .. housing, 20... Communication connector.

Claims (4)

A magnetic member;
A stress generating member attached integrally with the magnetic member and having a coefficient of thermal expansion different from that of the magnetic member;
A magnetic body for a filter comprising:   The filter magnetic body according to claim 1, wherein a thermal expansion coefficient of the stress generating member is larger than a thermal expansion coefficient of the magnetic member.   The filter magnetic body according to claim 1, wherein the stress generating member is attached in the magnetic member.   A communication connector comprising the filter magnetic body according to claim 1 in a bus terminal portion.

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