Noise filter

Abstract

The noise filter includes: a capacitor; an inductor; a sealing part which accommodates the capacitor; and a non-sealing part which accommodates the inductor and is at least partially open to the outside air.

Description

Technical Field

[0001] The invention relates to a noise filter. Background Art

[0002] When a power conversion device, such as a motor drive device, is driven, high-frequency noise is generated from a built-in switching element. In order to remove the high-frequency noise, a filter, such as a noise filter, is provided at the input portion of the power conversion device. Such a noise filter includes a capacitor and an inductor (for example, Japanese Patent Publication No. 2021-121143).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-121143 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The heat generated by the capacitor when the noise filter is used is relatively small, but most capacitors contain flammable materials such as electrolytic paper, plastic film, and insulating oil. In addition, in capacitors with structures having thin metal films, such as vapor-deposited electrode films, metal spraying, etc., the metal oxidizes due to external temperature and humidity, and the performance of the capacitor deteriorates over time. Therefore, if the inductor in the noise filter heats up and its influence spreads to the capacitor for a long time, the capacitor may fail, and in the worst case, it may catch fire.

[0008] Therefore, a noise filter that is highly safe and easy to maintain is desired.

[0009] Solutions to Solve Problems

[0010] According to a first aspect of the present disclosure, there is provided a noise filter including: a capacitor; an inductor; a sealed portion that accommodates the capacitor; and a non-sealed portion that accommodates the inductor and is at least partially open to the outside air.

[0011] The objects, features, and advantages of the present disclosure will become more apparent from the following description of the embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a perspective view of the noise filter in the first embodiment.

[0013] Figure 2 yes Figure 1 An exploded perspective view of the noise filter shown.

[0014] Figure 3A is a cross-sectional view of a noise filter in a modified example.

[0015] Figure 3B is a cross-sectional view of a noise filter in another modified example.

[0016] Figure 4A It is a perspective view of a noise filter in the second embodiment.

[0017] Figure 4B It is a perspective view of a noise filter in the third embodiment.

[0018] Figure 4C It is a perspective view of a noise filter in a fourth embodiment.

[0019] Figure 4D It is a perspective view of a noise filter in a fifth embodiment. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the drawings, corresponding components are denoted by common reference numerals.

[0021] Figure 1 is a perspective view of the noise filter in the first embodiment, Figure 2 yes Figure 1 As shown in these figures, the noise filter 5 is an LC filter mainly including a capacitor 11 and an inductor 21. The noise filter 5 is connected to a power conversion device, such as a motor drive device, via the connector 30.

[0022] exist Figure 1 and Figure 2 In the embodiment of the present invention, a plurality of capacitors 11 are arranged on a substrate 12, but the noise filter 5 may include a single capacitor. The number of capacitors 11 is appropriately changed according to the required capacitance. A typical capacitor 11 includes two conductors (not shown) insulated by a dielectric.

[0023] In addition, Figure 1 and Figure 2 In the embodiment, a plurality of inductors 21 are arranged in parallel. However, the noise filter 5 may also include a single inductor. The inductor 21 mainly includes a coil. A core made of a magnetic body may also be arranged at the center of the coil. In other words, the inductor 21 may also be a reactor.

[0024] The capacitors 11 and the inductors 21 are electrically connected to each other via the connection portion 39. The connection portion 39 may be a flexible conductor, such as a conductive wire, or a hard conductor, such as a bus bar. Typically, the connection portion 39 includes a resistor (not shown) between the capacitor 11 and the inductor 21. In other embodiments, the connection portion 39 is sometimes omitted. The noise filter 5 including the capacitor 11 and the inductor 21 is well known, so additional description is omitted.

[0025] like Figure 1 and Figure 2 As shown, the capacitor 11 is accommodated in the sealed portion 10. As shown in the figure, the sealed portion 10 is preferably a rectangular parallelepiped, but it can also be other forms, such as a cylindrical shape. The sealed portion 10 is preferably made of a flame retardant material, such as metal. However, the sealed portion 10 can also be made of a resin to which an organic flame retardant or an inorganic flame retardant is added.

[0026] The sealed part 10 does not include a communicating portion such as an opening, a notch, a valve, etc. for communicating the inner space of the sealed part 10 with the outer space. The boundary between the adjacent outer surfaces of the sealed part 10 is preferably sealed with a sealant, etc., but does not necessarily need to be sealed.

[0027] Furthermore, the connection portion 39 is connected to the capacitor 11 through a hole (not shown) formed in the sealing portion 10. The size of the hole formed in the sealing portion 10 is sufficient and necessary to allow the connection portion 39 to pass through. The hole and the connection portion 39 may be sealed.

[0028] The inductor 21 is accommodated in the non-sealed portion 20. The non-sealed portion 20 is preferably a rectangular parallelepiped, but may be in other forms, such as a cylindrical shape. At least one opening 29 is formed in the non-sealed portion 20. Therefore, the internal space and the external space of the non-sealed portion 20 are connected to each other through the opening 29. The non-sealed portion 20 is also preferably formed of the same material as the sealed portion 10.

[0029] exist Figure 1 and Figure 2 In the embodiment, the opening 29 is formed on one end face 27 of the non-sealed portion 20. However, other openings 28 may be formed on other faces of the non-sealed portion 20, such as the other end face 26 and the side face. Alternatively, the opening 29 may be formed on a portion of the upper surface of the non-sealed portion 20 where the sealed portion 10 is not configured.

[0030] from Figure 2It can be seen that a plate-like portion 25 is arranged horizontally between the sealed portion 10 and the non-sealed portion 20. The plate-like portion 25 can be formed of the same material as the sealed portion 10, or the plate-like portion 25 can also be formed of a heat insulating material. As shown in the figure, the plate-like portion 25 can also play a role as a cover of the non-sealed portion 20 together with the covers 30a and 30b for the connector 30. The covers 30a and 30b are also formed of the same material as the sealed portion 10.

[0031] Furthermore, the sealed portion 10 and the non-sealed portion 20 are preferably fixed to each other by a fixing member 35, such as a screw. Figure 2 In the embodiment, the flange portion of the sealed portion 10 is fixed to the non-sealed portion 20 including the plate-shaped portion 25 by a fixing member 35. Preferably, the sealed portion 10 and the non-sealed portion 20 are respectively made replaceable.

[0032] In this way, the capacitor 11 of the noise filter 5 in the present disclosure is accommodated in the sealed portion 10, and the inductor 21 is accommodated in the non-sealed portion 20. When a power conversion device, such as a motor drive device, is driven, high-frequency noise is generated from the switching element of the power conversion device. The noise filter 5 connected to the power conversion device has the function of removing high-frequency noise.

[0033] However, due to the power conversion device itself, the capacitor 11 may deteriorate over the years, and the temperature of the capacitor may rise due to self-heating. In addition, due to the heat of the inductor 21 of the noise filter 5 and the humidity of the outside air, the metal electrode inside the capacitor 11 is oxidized, and the various characteristics of the capacitor are deteriorated. As a result, there is a situation where the temperature of the capacitor rises due to self-heating. In addition, the capacitor 11 may include an overlapping body of electrolytic paper or plastic film and metal foil, or a metallized film with metal evaporated on the plastic film. Moreover, in large capacitors, such overlapping bodies and metallized films are often impregnated with electrical insulating oil. That is, the capacitor 11 may include a variety of combustible substances. In such a case, the heat of the inductor 21 promotes the degradation of the capacitor 11, and in the worst case, the combustible substances in the capacitor 11 may catch fire.

[0034] In the present disclosure, the capacitor 11 is sealed by the sealed portion 10. That is, the capacitor 11 is isolated from the inductor 21 in the non-sealed portion 20. Therefore, the capacitor 11 in the sealed portion 10 is not easily affected by the heat of the inductor 21.

[0035] Furthermore, even if the combustible material of the capacitor 11 ignites, since the capacitor 11 is housed in the sealing portion 10 , the influence of the ignition of the capacitor 11 is unlikely to affect the inductor 21 .

[0036] Therefore, even if the capacitor 11 of the sealed part 10 is damaged, the possibility of damage to the inductor 21 in the non-sealed part 20 is small. Therefore, when the capacitor 11 is damaged, the fixing member 35 is removed to separate the sealed part 10 including the capacitor 11 from the non-sealed part 20, and a new sealed part 10 of the same structure is assembled to the non-sealed part 20.

[0037] As can be seen from the above, in the first embodiment, the safety of the noise filter 5 can be greatly improved, and the maintainability of the noise filter 5 can be improved.

[0038] Figure 3A is a cross-sectional view of a noise filter in a modified example. Figure 3A The noise filter 5' shown includes a housing 6, and a plate-shaped portion 25a arranged in the horizontal direction divides the internal space of the housing 6 into an upper portion and a lower portion. In addition, the upper portion of the housing 6 functions as a sealed portion 10 in which a capacitor 11 and the like are arranged. In addition, the lower portion of the housing 6 functions as a non-sealed portion 20 in which an inductor 21 and the like are arranged. For this purpose, an opening 29 is formed on the end surface 27 of the lower portion of the housing 6.

[0039] In other words, the plate-like portion 25a is a part of the wall portion constituting the sealed portion 10, and is also a part of the wall portion constituting the non-sealed portion 20. Furthermore, the plate-like portion 25a can function as a partition plate that isolates the sealed portion 10 and the non-sealed portion 20 from each other in the housing 6. In addition, an opening 28 may be additionally formed on the end surface 26 of the lower portion of the housing 6. Figure 3A In the modified example shown, in addition to the above-described effects, the effect of easily forming the sealed portion 10 and the non-sealed portion 20 can be obtained by arranging only the plate-shaped portion 25 in the housing 6 where the opening 29 and the like are formed.

[0040] Figure 3B FIG. 4 is a cross-sectional view of a noise filter in another modified example. Figure 3B In the noise filter 5a shown, two plate-like parts 25b and 25c are arranged in parallel with each other in the horizontal direction in the housing 6. The internal space of the housing 6 is divided into three by these plate-like parts 25b and 25c. Moreover, the uppermost space functions as a sealed part 10 in which a capacitor 11 and the like are arranged. Furthermore, the lowermost space functions as a non-sealed part 20 in which an inductor 21 and the like are arranged. For this purpose, an opening 29 is formed on the end face 27 of the corresponding lower part of the housing 6.

[0041] The space between the plate-like portions 25b and 25c is an isolation space 40 that isolates the capacitor 11 and the inductor 21 from each other. In the isolation space 40, the control printed circuit board 13 and the like used in the noise filter 5a are arranged. Figure 3BThe intermediate space shown in the figure is configured as a non-sealed portion, and an opening 38 is formed in the wall portion 36 of the housing 6. However, the isolated space portion 40 may be configured as a sealed portion without forming the opening 38.

[0042] exist Figure 3B In the modified example shown, an isolation space portion 40 is arranged between the uppermost space where the capacitor 11 is arranged and the lowermost space where the inductor 21 is arranged. Since the isolation space portion 40 itself has a heat-insulating effect, even when the inductor 21 is heated, the capacitor 11 in the sealed portion 10 is less likely to be affected by the heat of the inductor 21. Similarly, it can be seen that even when the combustible material of the capacitor 11 catches fire, the inductor 21 is less likely to be affected by the ignition of the capacitor 11. Therefore, the safety of the noise filter 5a can be further improved. In addition, the internal space of the isolation space portion 40 can also be filled with a heat-insulating material.

[0043] exist Figure 3B In the embodiment, a sensor 32 as a detection unit is also arranged in the internal space of the sealed portion 10. The sensor 32 is a temperature sensor or a smoke sensor, and is connected to the control printed circuit board 13. Moreover, when the sensor 32 detects that the temperature of the internal space of the sealed portion 10 becomes higher than a predetermined temperature, or smoke is generated in the internal space of the sealed portion 10, the information is output through the output unit 33. The output unit 33 can be a lamp or a speaker provided on the outer surface of the noise filter 5. Alternatively, the operation screen of the power conversion device connected to the noise filter 5, such as the NC device that controls the motor drive device, can be used as the output unit 33 to display the above information.

[0044] The output portion 33 is preferably disposed at a location other than the sealed portion 10, such as the outer surface of the non-sealed portion 20, or Figure 3B As shown, the output portion 33 is provided on the outer surface of the isolation space portion 40. In the case where the capacitor 11 in the sealed portion 10 is damaged due to heat, the sealed portion 10 can be completely separated, a new sealed portion 10 can be assembled, and the signal line (not shown) extending from the output portion 33 can be connected to the sensor 32. Therefore, even if the capacitor 11 in the sealed portion 10 is damaged, it is possible to avoid damage to the output portion 33 provided at a location other than the sealed portion 10.

[0045] In addition, the predetermined temperature is, for example, a value that is a predetermined temperature lower than the ignition temperature of the combustible material included in the capacitor 11. Since the sensor 32 is provided, it is possible to recognize in advance that the capacitor 11 may catch fire, and issue a warning to the outside through the output unit 33. Therefore, it is possible to prevent the capacitor 11 from actually catching fire in advance.

[0046] Furthermore, in Figure 3BIn the embodiment, the fan 31 is arranged on the end face 26 side of the housing 6 in the internal space of the non-sealed portion 20. The fan 31 introduces external air into the internal space of the non-sealed portion 20 through the opening 28 of the end face 26 to air-cool the inductor 21, and exhausts it from the opening 29 of the other end face 27. The fan 31 can air-cool the inductor 21, thereby reducing the influence of heat on the capacitor 11. Of course, the fan 31 can also be provided in the noise filter of other embodiments.

[0047] However, when the inductor is air-cooled by a fan, the capacitor may catch fire. In the case of such an incident, the capacitor is not contained in a sealed portion in the prior art, so the flame generated in the capacitor is blown out of the noise filter through the fan. As a result, there is a possibility that the inductor is overheated by the flame and the inductor is damaged. In addition, the flame extends to the outside of the noise filter through the opening of the end face where the fan is not configured (corresponding to the opening 29), thereby causing the danger of burning objects configured around the noise filter.

[0048] However, in the present disclosure, the capacitor 11 is accommodated in the sealed portion 10, so even if the capacitor 11 catches fire, the flame will not reach the inductor 21 arranged in the internal space of the non-sealed portion 20. In addition, the flame will not reach the internal space of the non-sealed portion 20, so the flame will not extend to the outside of the noise filter 5 through the opening 29 due to the fan 31. That is, even if the noise filter 5 is provided with the fan 31 in the non-sealed portion 20, the objects arranged around the noise filter 5 will not be spread to the fire. Therefore, even if the fan 31 is provided, a noise filter 5 with high safety can be provided.

[0049] Figure 4A 3 is a perspective view of a noise filter in the second embodiment. The connection portion 39 in the second embodiment is a flexible conductor, such as a wire. Therefore, in the second embodiment, the positional relationship between the sealed portion 10 and the non-sealed portion 20 can be freely changed within the length of the connection portion 39 (conductive wire). Therefore, the overall configuration of the noise filter 5b can be flexibly changed according to the environment where a power conversion device or the like is configured.

[0050] For example, in the case where only a narrow space is available, Figure 4A As shown, the sealed portion 10 and the non-sealed portion 20 can be arranged in series in the horizontal direction. In addition, in a space where the distance in the height direction is relatively long and the distance in the horizontal direction cannot be ensured, the sealed portion 10 and the non-sealed portion 20 can be arranged in a stacked manner (refer to Figure 1Alternatively, although not shown in the drawings, in an environment where there is a step, the sealed portion 10 may be disposed on the upper side of the step, and the non-sealed portion 20 may be disposed on the lower side of the step.

[0051] Figure 4B FIG. 1 is a perspective view of a noise filter in the third embodiment. Figure 4B The housing 6 of the noise filter 5c shown in the figure is provided with a plate-like portion 25d extending in the vertical direction. Figure 4B In the embodiment, the plate-like portion 25d is arranged at the central portion of the width of the housing 6 in the horizontal direction, but the plate-like portion 25d may be arranged at a portion other than the central portion.

[0052] The left side of the housing 6 functions as a sealed portion 10 in which a capacitor 11 and the like are arranged. The right side of the housing 6 functions as a non-sealed portion 20 in which an inductor 21 and the like are arranged. For this purpose, an opening 28 is formed on an end surface 26 of the lower portion of the housing 6. In other words, the plate-like portion 25d is a part of the wall portion constituting the sealed portion 10, and is a part of the wall portion constituting the non-sealed portion 20.

[0053] Figure 4B The structure shown is Figure 3A Therefore, it is possible to obtain a modification of the structure shown in FIG. Figure 3A In addition, in the third embodiment, two plate-like portions 25 parallel to each other may be arranged in the vertical direction in the shell 6, the rightmost portion may be used as the sealed portion 10, the leftmost portion may be used as the non-sealed portion 20, and the middle portion may be used as the above-mentioned isolation space portion 40.

[0054] Figure 4C FIG. 4 is a perspective view of a noise filter in accordance with a fourth embodiment. Figure 4C In the noise filter 5d shown, the sealed portion 10 is arranged in a stacked manner above the non-sealed portion 20. In this structure, the wall portion on the bottom side of the sealed portion 10 can also be shared with the wall portion above the non-sealed portion 20. The sealed portion 10 can also be arranged at the corner of the upper surface of the non-sealed portion 20.

[0055] Figure 4D FIG. 1 is a perspective view of a noise filter in the fifth embodiment. Figure 4D In the noise filter 5e shown, the sealed portion 10 is arranged in the internal space of the non-sealed portion 20. In this structure, the wall portion on the bottom side of the sealed portion 10 can also be shared with the wall portion on the bottom side of the non-sealed portion 20. In addition, the structure in which the non-sealed portion 20 is arranged in the internal space of the sealed portion 10 can also be used.

[0056] In addition, the internal space of the sealed portion 10 may be at least partially filled with a resin, such as a flame retardant resin. Thus, the amount of oxygen in the internal space of the sealed portion 10 is reduced, thereby suppressing the possibility of the capacitor 11 in the sealed portion 10 catching fire.

[0057] As an effect of at least one of the embodiments and the modified examples described above, the safety of the noise filter 5 can be greatly improved, and the maintainability of the noise filter 5 can be improved.

[0058] The embodiments of the present disclosure are described in detail, but the present disclosure is not limited to the above-mentioned embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. without departing from the scope of the main purpose of the invention, or without departing from the idea and main purpose of the present invention derived from the contents recorded in the scope of the technical solution and its equivalents. For example, in the above-mentioned embodiments, the order of each action and the order of each processing are shown as an example, but are not limited to this. In addition, the same is true for the case where numerical values ​​or mathematical formulas are used in the description of the above-mentioned embodiments. Furthermore, several appropriate combinations of the aforementioned embodiments are included in the scope of the present disclosure.

[0059] The following supplementary notes are further disclosed with respect to the above-mentioned embodiment and modified examples.

[0060] (Supplementary Note 1) A noise filter includes: a capacitor; an inductor; a sealed portion that accommodates the capacitor; and a non-sealed portion that accommodates the inductor and is at least partially open to the outside air.

[0061] (Supplementary Note 2) The noise filter according to Supplementary Note 1, wherein the capacitor includes a flammable substance.

[0062] (Supplementary Note 3) The noise filter according to Supplementary Note 1 or 2, further comprising a connection portion that electrically connects the capacitor and the inductor, wherein the connection portion is a conductive wire.

[0063] (Supplementary Note 4) The noise filter according to any one of Supplementary Notes 1 to 3, further comprising a detection unit that is provided in the sealed portion and detects a state of an internal space of the sealed portion.

[0064] (Supplementary Note 5) The noise filter according to any one of Supplementary Notes 1 to 4, wherein the noise filter includes a housing, and an internal space of the housing is partitioned by a partition to form the sealed portion and the non-sealed portion.

[0065] (Supplementary Note 6) The noise filter according to any one of Supplementary Notes 1 to 5, wherein an internal space of the sealing portion is filled with resin.

[0066] (Supplementary Note 7) The noise filter according to any one of Supplementary Notes 1 to 6, wherein at least a part of the wall of the sealed portion is shared with the wall of the non-sealed portion.

[0067] (Supplementary Note 8) The noise filter according to any one of Supplementary Notes 1 to 7, further comprising a fan that is disposed in the non-sealed portion and cools an internal space of the non-sealed portion.

[0068] Explanation of symbols

[0069] 5, 5', 5a~5e—noise filter, 6—housing, 10—sealed part, 11—capacitor, 12—substrate, 13—printed substrate for control, 20—unsealed part, 21—inductor, 25, 25a~25d—plate-shaped part, 28, 29, 38—opening part, 31—fan, 32—sensor (detection part), 35—fixing part, 39—connecting part, 40—isolation space part.

Claims

1. A noise filter, It is characterized in that include: Capacitors; Inductors; a sealing portion accommodating the capacitor; as well as The non-sealed portion accommodates the inductor and is at least partially open to the outside air.

2. The noise filter according to claim 1, It is characterized in that The capacitor includes a combustible substance.

3. The noise filter according to claim 1 or 2, It is characterized in that further comprising a connection portion for electrically connecting the capacitor and the inductor, The connecting portion is a wire.

4. The noise filter according to any one of claims 1 to 3, It is characterized in that A detection unit is provided, the detection unit being disposed in the sealed portion and detecting a state of an internal space of the sealed portion.

5. The noise filter according to any one of claims 1 to 4, It is characterized in that The noise filter comprises a housing, The sealed portion and the non-sealed portion are formed by partitioning the inner space of the housing using a partition.

6. The noise filter according to any one of claims 1 to 5, It is characterized in that The internal space of the sealing portion is filled with resin.

7. The noise filter according to any one of claims 1 to 6, It is characterized in that At least a portion of the wall of the sealed portion is shared with the wall of the non-sealed portion.

8. The noise filter according to any one of claims 1 to 7, It is characterized in that A fan is further provided, the fan being disposed in the non-sealed portion and cooling an internal space of the non-sealed portion.

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