JPH0563114U - Noise filter for large current with case - Google Patents

Abstract

(57) [Abstract] [Purpose] By adopting a structure in which the choke coil and the capacitor are thermally isolated from each other by the terminal plate, the adverse effect on the capacitor due to the heat generation of the coil is suppressed and the heat dissipation efficiency of the capacitor is improved. [Constitution] The choke coil 15 is housed in the case 1,
It has a structure in which a terminal plate 2 provided with metal terminals is attached to the case opening, and the choke coil 15 and the capacitor 16 are provided.
The terminal board 2 is arranged between A, 16B, etc. to thermally isolate the choke coil and the capacitor.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 INDUSTRIAL APPLICABILITY The present invention is used for attenuating an external surge or impulse noise that enters an electronic device such as an office automation device or a home electric appliance through a power line, or for attenuating a conductive noise leaking from an electronic device through a power line. The present invention relates to a large current noise filter with a case for current.

[0002]

[Prior Art]

 Fig. 8 shows a conventional example of a large-current noise filter used to attenuate external surges and impulse noises that enter electronic equipment through the power supply line, and to attenuate conducted noise that leaks from electronic equipment through the power supply line. .. The cylindrical noise filter for large current of FIG. 8 includes a common mode choke coil 15 in which a trojan core made of ferrite or the like is covered with an insulating core cover and a pair of windings is provided thereon, and an inter-line capacitor 16 is provided. It is arranged inside a bottomed cylindrical metal case 31 having a screw portion 37, and a terminal plate 34 provided with an input / output terminal 35 is fixed to the opening end face of the metal case 31 and wired. In this case, the choke coil 15 is arranged with an insulating plate 36 interposed between the choke coil 15 and the inner bottom surface of the bottomed cylindrical metal case 31, and the resin 8 is poured and fixed by resin casting.

[0003]

[Problems to be solved by the device]

 By the way, FIG. 9 is a graph showing the temperature rise of each part of the conventional large current noise filter shown in FIG. 8, in which the vertical axis represents temperature (° C.) and the horizontal axis represents energization time (minutes). (D), (e), and (f) show the surface temperature of the common mode choke coil 15 of the noise filter, the surface temperature of the interline capacitor 16, and the ambient temperature of the bottomed cylindrical metal case 31, respectively. From this graph, it can be seen that the temperature (d) of the choke coil 15 and the temperature (e) of the capacitor 16 approach and rise. In the case of this conventional example, the choke coil 15 is arranged on the inner bottom surface of the bottomed cylindrical metal case 31 and resin casting is performed to radiate heat, but the capacitor (ceramic capacitor, film capacitor) 16 is a heating element. Since it is assembled close to the coil 15 and the inside of the metal case 31 is almost hermetically sealed, heat is trapped inside the metal case 31 and the choke coil 15 and the capacitor 16 cannot be sufficiently dissipated. Will rise. In this case, in order to keep the temperature rise (e) of the capacitor 16 with respect to the ambient temperature (f) within about 35 degrees, it is necessary to suppress the temperature rise (d) with respect to the ambient temperature of the coil 15 within 55 degrees. The capacitor 16 has a problem such as deterioration in characteristics when the temperature rises, so the capacitor 16 must be used within an allowable temperature. Therefore, when used for a large current, it is necessary to increase the wire diameter and the core shape in consideration of the heat generation of the choke coil 15. Therefore, it is necessary to increase the coil storage space, and the noise filter shape is enlarged. I hate to do it.

Further, when fixing the terminal plate 34, the positions of the coil 15 and the capacitor 16 cannot be accurately defined, so that the coil 15 and the capacitor 16 must be manually fixed and simultaneously assembled in the metal case 31. However, it was troublesome and the workability was poor.

In view of the above, the present invention suppresses the adverse effect on the capacitor due to the heat generation of the coil by adopting the structure in which the choke coil is arranged in the case and the choke coil and the capacitor are thermally separated by the terminal plate. It is an object of the present invention to provide a noise filter for a large current with a case, which improves the heat dissipation efficiency of the capacitor, enables miniaturization of the choke coil, and thus miniaturizes the overall shape, and reduces the cost.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, a noise filter for large current with a case of the present invention has a structure in which a choke coil is housed in a case, and a terminal plate provided with a metal terminal is attached to the case opening. The terminal plate is arranged between the capacitor and the capacitor to thermally isolate the choke coil and the capacitor.

[0007]

[Action]

 The large-current noise filter with case of the present invention has a choke coil housed in the case, a terminal plate provided with metal terminals is attached to the case opening, and the terminal plate is provided between the choke coil and the capacitor. By arranging them to thermally isolate the choke coil and the capacitor, the heat generation of the choke coil does not affect the capacitor due to the interposition of the terminal plate, and the allowable temperature of the choke coil can be increased. As for the choke coil, it is possible to reduce the size of the choke coil, which in turn reduces the overall size of the noise filter and reduces the cost. As a result, the assembly space required in the case is no longer necessary, the height dimension can be reduced, and it is possible to obtain a large-current noise filter with a reduced external dimension, which can be used in electronic equipment in a small space. Can be installed. In addition, in the case of a capacitor, heat transfer due to a rise in coil temperature is prevented, and since it comes into contact with the outside air, heat dissipation efficiency is improved and a decrease in reliability due to a rise in temperature can be avoided. In addition, the terminal plate can be easily molded by using a resin having low thermal conductivity.

Further, when connecting and fixing the leads of the coil and the capacitor to the input / output terminal and the ground terminal of the terminal board, if the structure is such that the leads are inserted into the groove of each terminal and caulked, the lead is fixedly connected. It is also possible to automate the soldering process and the soldering work, which is effective in reducing the number of steps.

[0009]

【Example】

 An embodiment of a large-current noise filter with a case according to the present invention will be described below with reference to the drawings.

1 to 4 show a first embodiment of the present invention, FIGS. 1 to 3 show the structure of a noise filter, and FIG. 4 shows an electrical connection. In these figures, reference numeral 1 denotes a bottomed cylindrical metal case obtained by aluminum impact molding or the like, and a screw portion 7 used for attaching to a chassis or the like of an electronic device is integrally formed. Reference numeral 2 is a terminal plate made of an insulating resin (preferably one having poor heat conduction), which is provided with a storage recess 3 which is open to the outside, and four input / output terminals 4A to 4D are provided with terminal insertion holes. It is fixed by being inserted in each of 26. A ground terminal 5 is inserted and fixed in the terminal plate 2. The first lead connecting portion (vertical bending portion) 27 of each of the input / output terminals 4A to 4D has a lead locking groove 9 and the second lead connecting portion (horizontal bending portion) 28 has a lead locking portion. 9A are formed respectively, and similarly, a groove 9B for lead locking is formed in the ground terminal 5. A fixing hole 10 is provided at the lower end of the ground terminal 5.

As shown in FIGS. 1 to 3, the inter-line capacitors 16 A and 16 B and the line-to-earth capacitors 17 A and 17 B are accommodated in the accommodating concave portion 3 of the terminal plate 2, and the common under the terminal plate 2. The mode choke coil 15 is arranged. The common mode choke coil 15 is made by covering an insulating core cover on a ferrite core made of ferrite or the like, and providing a pair of windings 15A and 15B thereon as shown in the electrical connection diagram of FIG. 4 (as compared with the conventional example of FIG. 8). It is similar, but the external dimensions are small.) In the terminal plate 2, the leads of the common mode choke coil 15 are inserted along the side wall of the housing recess 3 and the guide holes 11 (the lower openings are formed in the grooves 9A of the input / output terminals 4A to 4D) are inserted. 4 are formed in a taper shape, and each lead of the coil 15 penetrates the guide hole 11 from the lower side of the terminal plate 2 to the upper side of the second lead connecting portion 28 of each input / output terminal. It reaches the groove 9A. As shown in the electrical connection diagram of FIG. 4, windings 15A and 15B of the common mode choke coil are connected between the input / output terminals 4A and 4C, 4B and 4D, respectively, and between the input / output terminals 4A and 4B, Line capacitors 16A and 16B are connected between 4C and 4D, respectively. Line-to-ground capacitors 17A and 17B are connected between the input / output terminal 4C and the ground terminal 5 and between the input / output terminal 4D and the ground terminal 5, respectively. The leads of the coil 15 and the capacitors 16A, 16B, 17A, 17B to be connected to the respective terminals are inserted into the lead locking grooves 9, 9A, 9B, respectively, and then the connecting portions 27, 28 of the respective input / output terminals are connected. The upper portion of the ground terminal 5 is mechanically fixed by caulking as shown by the arrow X in FIGS. 1 and 2, and further fixed to each terminal by soldering.

Then, the insulating plate 6 is arranged on the bottom surface and the inner peripheral surface of the bottomed cylindrical metal case 1, and a predetermined amount of the insulating resin 8 is poured into the insulating plate 6, and before the resin 8 is solidified, the choke coil described above is set. 15 and the capacitors 16A, 16B, 17A and 17B are arranged and fixed, and the terminal plate 2 is fitted into the metal case 1 as shown in the figure. As a result, the common mode choke coil 15 is fixed by resin casting in a state of being very close to the bottomed cylindrical metal case 1 with the insulating plate 6 interposed between the bottomed cylindrical metal case 1 and the bottom surface. It The windings 15A, 15B and the bottomed cylindrical metal case 1 are reliably insulated with an insulating plate 6 interposed. At this time, the fixing hole 10 at the lower end of the ground terminal 5 and the fixing hole 12 formed in the bottomed cylindrical metal case 1 are aligned with each other, and the rivet 13 or the like is inserted into the holes 10 and 12 and caulked. Thus, the ground terminal 5 and the metal case 1 are electrically connected. The terminal plate 2 is fixed to the open end surface of the bottomed cylindrical metal case 1, but the terminal plate 2 is provided with a step 14 so as to fit with the bottomed cylindrical metal case 1 as shown in FIG. Yes, these joints are securely fixed by means such as caulking and gluing. The choke coil 15 housed and arranged inside the bottomed cylindrical metal case 1 and the capacitors 16A, 16B, 17A, 17B at positions exposed to the outside air are heated via the bottom surface of the housing recess 3 of the terminal board 2. Electrically isolated and electrically isolated. When the resin 8 is solidified, the common mode choke coil 15 is fixed by resin casting, and the noise filter having the cylindrical housing metal case is completed.

FIG. 5 is a graph showing the temperature rise of each part of the first embodiment, in which the vertical axis shows the temperature (° C.) and the horizontal axis shows the energizing time (minutes), and the curves (a), (b) , (C) are the surface temperature of the choke coil 15 of the noise filter for large current with case, the surface temperature of the line-to-line capacitors 16A and 16B (the surface temperature of the line-to-earth capacitor is substantially the same), and the metal case. The respective ambient temperatures of 1 are shown. As can be seen from these curves, by thermally isolating the coil 15 and each capacitor with the terminal plate 2, it is possible to suppress the temperature rise of the capacitor. For example, in order to keep the temperature rise of the capacitor with respect to ambient temperature (C) within 35 degrees, which is the same as before, expand the allowable range of temperature rise of the choke coil with respect to ambient temperature (C) to within 75 degrees. You can Therefore, since the allowable temperature of the choke coil 15 can be increased, the allowable amount of heat generation of the choke coil can be increased, so that the wire diameter and core shape of the winding can be reduced and the choke coil can be downsized. As a result, it is possible to reduce the overall size of the noise filter and reduce its cost. For example, conventionally, the choke coil 15 has a core size of 19 mm inside diameter, 31 mm outside diameter, 13 mm height, wire diameter 1.7 mm, winding number of 14 turns (on one side of winding), and inductance of 1.2 mH, and case size is outside. The diameter was 44 mm and the height was 59 mm, but in the first embodiment, the core dimensions of the choke coil 15 are 15 mm inside diameter, 25 mm outside diameter, 10 mm height, 1.6 mm wire diameter, and 13 turns (on one side of the winding). The inductance is 1.2 mH, and the case size can be 42 mm in height with an outer diameter of 44 m. As for each of the capacitors 16A, 16B, 17A, 17B, as is clear from the comparison between the case of the present embodiment of FIG. 5 and the conventional example of FIG. 9, the conduction of heat generation due to the rise of the temperature of the coil 15 is prevented. As a result, it is possible to suppress the temperature rise of each capacitor and avoid the decrease in reliability due to the temperature rise.

According to the configuration of the first embodiment described above, the choke coil 15 is insulatively insulated from the bottomed cylindrical metal case 1, and is closely or closely contacted with the bottomed cylindrical metal case 1 for resin casting. Together, by arranging the terminal plate 2 between the choke coil 15 and the capacitors 16A, 16B, 17A, 17B and thermally isolating them, even if heat is trapped inside the metal case 1, the choke coil 15 Is difficult to transfer to the capacitors 16A, 16B, 17A, 17B, and the capacitors 16A, 16B, 17A, 17B come into contact with the outside air, so that the heat dissipation efficiency of the capacitors can be improved.

In addition, it is extremely easy to provide the resin-made terminal plate 2 with the accommodating recess 3 for accommodating the capacitor and the guide hole 11, and the coil 15 and the capacitors 16A, 16B, 17A and 17B are separately incorporated in the terminal plate 2. In addition, by forming the coil 15 and the leads of the capacitors 16A, 16B, 17A, and 17B in advance, the coil 15 and the capacitor 16A, can be formed in the grooves 9 and 9A of the input / output terminals 4A to 4D. The 16B, 17A, and 17B leads can be easily inserted, and the insertion work of each lead can be automated if necessary. Further, when connecting the leads of the coil or the capacitor to the input / output terminals 4A to 4D of the terminal board 2 and the ground terminal 5, the leads can be inserted into the grooves 9, 9A, 9B of each terminal and caulked to be fixed. Fixing can be automated and is effective in reducing man-hours (work to tie leads to terminals can be omitted). It is also possible to automate the subsequent soldering work.

FIG. 6 shows a second embodiment of the present invention. In this case, paying attention to the fact that the outer diameter of the common mode choke coil 15 is smaller than that of the conventional one, the bottomed cylindrical metal case 1A is formed so as to taper toward the bottom (thinner). The common mode choke coil 15 is fixed by resin casting to the bottom of the metal case 1A via the insulating plate 6. Other configurations are similar to those of the first embodiment.

According to the configuration of the second embodiment, since the bottom volume of the bottomed cylindrical metal case 1A is small, the mounting space for the case 1A is reduced and the amount of resin 8 used for resin casting is reduced. Therefore, the cost can be reduced. The metal case 1A can be easily processed by aluminum impact molding or the like.

FIG. 7 shows a third embodiment of the present invention. This cased large current noise filter has a choke coil 15 housed inside a rectangular tube-shaped or box-shaped metal case 21 with both ends open, and a pair of terminal plates 22A and 22B are provided at both ends of the metal case 21. The inter-line capacitor 16A is housed in the housing recess 23A of the terminal board 22A and connected to the input / output terminals 25A and 25B of the terminal board 22A, and the housing recess 23B of the terminal board 22B is installed. The line-to-line capacitor 16B is housed in the terminal and connected to the input / output terminals 25C and 25D of the terminal board 22B. The leads of the winding 15A of the choke coil 15 are connected to the input / output terminals 25A and 25C through the guide holes 41 formed in the terminal plates 22A and 22B, and the leads of the winding 15B are connected to the terminal plates 22A and 22B. The choke coil 15 is connected to the input / output terminals 25B and 25D through the formed guide hole 41, and the choke coil 15 is fixed to the bottom of the metal case 21 by the resin casting using the resin 8 via the insulating plate 42.

Also in the third embodiment, the terminal plates 22A and 22B are interposed between the choke coil 15 and the inter-line capacitors 16A and 16B to thermally connect the choke coil 15 and the capacitors 16A and 16B. It can be isolated, and the same effect as that of the first embodiment can be obtained.

In each of the above embodiments, the lead holes of the choke coil are inserted through the terminal plate to guide the terminals, but the guide holes may be formed. Further, instead of the lead connection fixing grooves 9, 9A, 9B formed in the input / output terminal and the ground terminal, holes may be formed.

In the first and second embodiments, an example of the noise filter having one choke coil and four capacitors is shown, but other filter circuit configurations like the third embodiment are used. The present invention can also be applied to objects.

[0022]

[Effect of the device]

 As described above, the noise filter for large current with a case of the present invention can thermally isolate the choke coil and the capacitor by the terminal plate interposed between them, and reduce the adverse effect on the capacitor due to the heat generated by the choke coil. Therefore, the choke coil can be downsized, which in turn can reduce the overall size of the noise filter and reduce the cost. For this reason, it is possible to obtain a large current noise filter in which the outer dimensions of the case are reduced, and the noise filter can be mounted in an electronic device or the like in a small space. In addition, the reliability of capacitors can be prevented from lowering due to temperature rise.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a first embodiment of a large-current noise filter with a case according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a perspective view of the same.

FIG. 4 is a circuit diagram showing an electrical connection of the first embodiment.

FIG. 5 is a graph showing a temperature rise of each part of the first embodiment.

FIG. 6 is a front sectional view showing a second embodiment of the present invention.

FIG. 7 is a front sectional view showing a third embodiment of the present invention.

FIG. 8 is a front sectional view showing a conventional large-current noise filter with a case.

FIG. 9 is a graph showing a temperature rise of each part of the conventional example.

[Explanation of symbols]

 1, 1A Bottomed cylindrical metal case 2, 22A, 22B Terminal plate 3, 23A, 23B Storage recess 4A to 4D, 25A to 25D Input / output terminal 5 Earth terminal 6,42 Insulation plate 8 Insulating resin 9, 9A, 9B groove 11, 41 Guide hole 15 Common mode choke coil 16A, 16B Line-to-line capacitor 17A, 17B Line-to-ground capacitor

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Michiyuki Umehara 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation

Claims (3)

[Scope of utility model registration request] 1. A large-current noise filter with a case, wherein a choke coil is housed in a case, and a terminal plate provided with a metal terminal is attached to the case opening, wherein the terminal plate is provided between the choke coil and a capacitor. A noise filter for a large current with a case, wherein the choke coil and the capacitor are thermally isolated from each other. 2. The noise filter for a large current with a case according to claim 1, wherein a guide hole or groove for inserting the lead of the choke coil to guide the groove or hole of the metal terminal is formed in the terminal plate. 3. The noise filter for a large current with a case according to claim 1, wherein the case is formed so as to taper toward the bottom, and the choke coil is fixed to the bottom of the case by resin casting.