JP2004140261A - Transformer, switching power unit and manufacturing method of transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a howling of a transformer which is used for a switching power unit while securing reliability. <P>SOLUTION: A cylindrical cutoff member 50 is inserted into an axial hole 24 of a bobbin 20 around which a winding wire 10 is wound. A middle foot 34 of a ferrite core 30 and a middle foot 44 of a ferrite core 40 are inserted into the cylindrical cutoff member 50. A gap G between the middle foot 34 and the middle foot 44 is filled with adhesives 60. The cutoff member 50 cuts off the periphery of the gap G and the bobbin 20, and the adhesives 60 stuck out of the gap G are not stuck on the bobbin 20. Howling is suppressed by the adhesives 60, and the cutoff member 50 prevents a stress caused by heating from being loaded to the ferrite core 30 and the ferrite core 40. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transformer, a switching power supply using the transformer, and a method of manufacturing the transformer.
[0002]
[Prior art]
FIG. 10 is a sectional view showing an example of a conventional transformer (hereinafter, referred to as a transformer).
Conventionally, a switching transformer incorporated in a switching power supply device is generally designed to have a switching frequency higher than an audible frequency band. However, when the load becomes light during standby or the like, the power consumption can be suppressed by lowering the switching frequency of the switching power supply device. As described above, when the switching frequency of the switching power supply is reduced to drive the switching transformer in order to reduce the power consumption, the transformer for high-frequency driving is originally operated at a low frequency, for example, about the audio frequency. A beat was sometimes heard.
The audible beats generated from the switching transformer in this way are treated as abnormal sounds in various electronic devices.
[0003]
As shown in FIG. 10, the switching transformer includes a set of ferrite cores 1 and 2 and a bobbin 4 around which a winding 5 is wound. The middle legs 1a and 2a of the ferrite cores 1 and 2 are opposed to each other with a gap 3 therebetween.
[0004]
The abnormal noise is mainly generated in the gap 3 between the middle foot 1a of the ferrite core 1 and the middle foot 2a of the ferrite core 2 facing each other in the shaft hole 4a of the bobbin 4. The gap 3 is provided for appropriately adjusting the magnetic flux linked to the winding 5.
[0005]
As a countermeasure for suppressing abnormal noise, there is a method in which the varnish is impregnated by immersing the ferrite cores 1 and 2 and the bobbin 4 around which the winding 5 is wound in a varnish, and the gap 3 is filled with the varnish. As another measure for suppressing abnormal noise, there is a method in which an adhesive 6 is applied to the midfoot portions 1a and 2a of the ferrite cores 1 and 2 and the midfoot portions 1a and 2a are adhered to each other. .
[0006]
[Problems to be solved by the invention]
However, when the varnish is impregnated to prevent generation of abnormal noise, the varnish is not sufficiently distributed, and the effect may be incomplete.
On the other hand, the method of bonding the middle feet 1a and 2a of the ferrite cores 1 and 2 has the following problems.
[0007]
When the center foot 1a of the ferrite core 1 and the center foot 2a of the ferrite core 2 are brought close to each other in the shaft hole 4a of the bobbin 4, the adhesive 6 protrudes, and the protruding adhesive 6 is formed between the bobbin 4 and the ferrite cores 1, 2. Flow into the gap. Therefore, when the adhesive 6 is cured, the ferrite cores 1 and 2 and the bobbin 4 are integrated.
[0008]
When the ferrite cores 1, 2 and the bobbin 4 are integrated as described above, the thermal expansion coefficient of the ferrite cores 1, 2 and the bobbin 4 are different when heat is applied. The applied stress is applied to the ferrite cores 1 and 2. For example, while the bobbin 4 expands in the axial direction of the bobbin 4 as shown by an arrow A in FIG. Each of the feet 1a and 2a is subjected to a pulling force f toward the contact surface. The force f may cause the ferrite core 1 or 2 to be cracked or damaged.
[0009]
An object of the present invention is to provide a transformer, a switching power supply, and a method of manufacturing a transformer, which can suppress generation of abnormal noise while ensuring reliability.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a transformer according to a first aspect of the present invention includes a bobbin having a body having an axial hole formed in an axial direction, and a winding wound around the body of the bobbin. A first core having a foot portion inserted into a shaft hole of the bobbin, the first core having a foot portion inserted into a shaft hole of the bobbin, and a first core having a foot portion inserted into the shaft hole; A second core having an opposing portion opposing the foot and linking the magnetic flux to the winding in conjunction with the first core; and a filling filled between the foot and the opposing portion. A member and a blocking member for blocking between the filled filling member and the bobbin are provided.
[0011]
By adopting such a configuration, even when driven at a low frequency, the space between the foot portion of the first core and the opposing portion of the second core is filled with the filling member, so that an audible sound is generated. The occurrence of beats is suppressed. Further, since the blocking material blocks the space between the filling member and the bobbin, it is possible to prevent the bobbin from being integrated with the first core and the second core even when the temperature increases, and to prevent the first core or the first core from being integrated. The second core can be prevented from being damaged or cracked.
[0012]
A predetermined gap may be provided between the opposing portion and the foot of the first core, and the filling member may fill the gap.
Further, the filling member may be an adhesive.
Further, the opposing portion of the second core may be convex, and may oppose the foot portion within a shaft hole of the bobbin.
[0013]
Further, the blocking member may have a tubular shape, and may be inserted into a shaft hole of the bobbin. The blocking member may have a film shape, and a foot portion of the first core and the second core May cover the periphery of the filling member filled between the opposing portions of the member.
[0014]
In order to achieve the above object, a switching power supply according to a second aspect of the present invention includes a switching element that is turned on and off based on a control signal, and a primary winding in which a switching current flows from a power supply when the switching element is turned on. A wire, an arbitrary number of induction windings, a body having an axially formed axial hole, a bobbin around which the primary winding and the induction winding are wound, and a member for transmitting magnetic flux. A first core having a foot portion inserted into a shaft hole of the bobbin, and a facing portion formed of a member for transmitting magnetic flux and facing the foot portion of the first core; A second core for linking the magnetic flux to the primary winding and the induction winding in combination with the core, a foot portion of the first core, and a facing portion of the second core. Filling member, and shut off between the filling member and the bobbin A transformer having a disconnection material, input means for inputting energy accumulated by a switching current flowing through the primary winding from the induction winding, and converting the energy into electric power to be supplied to a load; and the switching element. And control means for generating the control signal for setting the timing of turning on and off the power supply.
[0015]
In order to achieve the above object, a method of manufacturing a transformer according to a third aspect of the present invention provides a method for manufacturing a transformer, wherein a winding is wound around a body portion having a shaft hole formed in an axial direction, A process of inserting a cylindrical blocking member, and a leg of the first core having a protruding leg formed of a member for transmitting magnetic flux, or a member for transmitting magnetic flux, facing the leg. Applying a filling member to one or both of the opposing portions of the second core having an opposing portion for causing the first core to have the foot portion inserted into the shaft hole; And the foot portion faces the opposing portion of the second core. When the filling member protrudes from between the opposing foot portion and the opposing portion, the protruding filling member is shut off. And a process of adhering to a member.
[0016]
The filling member may be an adhesive, and after the foot portion and the facing portion face each other, a process of curing the adhesive may be further performed.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a configuration diagram illustrating a transformer (hereinafter, referred to as a transformer) according to an embodiment of the present invention. FIG. 2 is a sectional view showing an example of the bobbin 20 in FIG. FIG. 3 is a front view showing the ferrite core 30 in FIG.
[0018]
The transformer illustrated in FIG. 1 includes a winding 10, a bobbin 20, a ferrite core 30, a ferrite core 40, and a blocking member 50. This transformer is used, for example, incorporated in a switching power supply device. The ferrite core 30 and the ferrite core 40 are bonded with an adhesive 60.
[0019]
The bobbin 20 is formed of a phenol resin or the like, and includes a body 21 and flanges 22 and 23 disposed at both ends of the body 21. The outer diameters of the flange 22 and the flange 23 are larger than the outer diameter of the body 21. A required number of, for example, three windings 10 are wound around the outer periphery of the body 21 so as not to protrude from the outer diameters of the flanges 22 and 23.
[0020]
The number of the windings 10 is, for example, three. In the axial direction of the body 21 of the bobbin 20, a shaft hole 24 that penetrates the flanges 22, 23 is formed, and the body 21 has a cylindrical shape. A plurality of pins 25 are implanted outside the flange 23. The pin 25 is connected to the winding 10 wound around the body 21 via a conductive member (not shown).
[0021]
The ferrite core 30 is formed of ferrite that transmits magnetic flux. As shown in FIG. 3, the support portion 31, a square pillar-shaped outer foot portion 32 protruding from the support portion 31, and a square pillar-shaped outer leg protruding from the support portion 31. It has a foot 33 and a columnar middle foot 34 protruding from the support 31. The middle foot 34 is arranged between the outer foot 32 and the outer foot 33. The outer foot portions 32 and 33 and the middle foot portion 34 face in the same direction, and the ferrite core 30 has an "E" shape. The length of the outer leg 32 and the length of the outer leg 33 are equal, and the length of the middle leg 34 is shorter than the outer legs 32 and 33.
[0022]
The ferrite core 40 has the same configuration as that of the ferrite core 30, and is formed of ferrite that transmits magnetic flux. The ferrite core 40 protrudes from the support 41, the quadrangular prism-shaped outer leg 42 protruding from the support 41, and the support 41. It has a square pillar-shaped outer leg 43 and a columnar middle leg 44 protruding from the support 41.
[0023]
The blocking member 50 is formed of, for example, a plastic having a cylindrical shape. The thickness of the blocking member 50 is arbitrary, and may be, for example, a cylindrical polyester film.
[0024]
The shielding member 50 is housed in the shaft hole 24 of the bobbin 20. The middle foot portion 34 of the ferrite core 30 and the middle foot portion 44 of the ferrite core 40 are inserted into the cylindrical inside of the blocking member 50, and their leading ends face each other with a gap G therebetween. The outer feet 32, 33 of the ferrite core 30 and the outer feet 42, 43 of the ferrite core 40 are in contact with each other. An adhesive 60 is filled in a gap G between the opposed midfoot portion 34 of the ferrite core 30 and the midfoot portion 44 of the ferrite core 40. The adhesive 60 is made of, for example, an epoxy resin. A part of the adhesive 60 protrudes from the gap and adheres to the blocking member 50.
[0025]
Next, a method of manufacturing the transformer shown in FIG. 1 will be described with reference to FIGS.
The bobbin 20 around which the winding 10 is wound and the blocking member 50 are prepared, and the blocking member 50 is inserted into the shaft hole 24 of the bobbin 20 and accommodated therein.
[0026]
After accommodating the blocking member 50 in the bobbin 20, the adhesive 60 is sufficiently applied to the tip of the middle foot portion 34 of the ferrite core 30 or the middle foot portion 44 of the ferrite core 40. The adhesive 60 is also applied to the outer feet 32, 33 of the ferrite core 30 or the outer feet 42, 43 of the ferrite core 40.
[0027]
Subsequently, the middle foot portion 34 of the ferrite core 30 and the middle foot portion 44 of the ferrite core 40 are inserted into the shaft hole 24 of the bobbin 20 containing the blocking member 50 from both sides of the shaft hole 24, as shown in FIG. The outer legs 32, 33 of the ferrite core 30 are brought into contact with the outer legs 42, 43 of the ferrite core 40 opposed thereto. By bringing the outer feet 32, 33 and 42, 43 into contact, a gap G is formed between the middle feet 34 and 44, which are shorter than the outer feet 32, 33, 42, 43. . The gap G is filled with the adhesive 60.
[0028]
The adhesive 60 protruding from the gap G adheres to the blocking member 50 and does not adhere to the bobbin 20. In this state, the adhesive 60 is cured. Before and after the adhesive 60 is cured, the ferrite core 30 is fixed to the flange 22 of the bobbin 20. Here, the flange 22 and the ferrite core 30 may be fixed with an adhesive or with a screw or the like.
[0029]
The transformer shown in FIG. 1 is incorporated in, for example, a switching power supply shown in FIG.
FIG. 5 is a circuit diagram showing a switching power supply device using a transformer.
This switching power supply device is a power factor correction circuit, and the transformer shown in FIG. The switching power supply device of FIG. 5 includes, in addition to a switching transformer 70, a full-wave rectifier circuit 82 connected to an AC power supply 81, an N-channel MOS transistor (hereinafter, referred to as an NMOS) 83 as a switching element, and a resistor 84. , A diode 85, a capacitor 86, voltage dividing resistors 87 and 88, voltage dividing resistors 89 and 90, a resistor 91, and a control circuit 100.
[0030]
The switching transformer 70 has a primary winding 10a, a secondary winding 10b and an tertiary winding 10c as induction windings, and the respective windings 10a to 10c are electromagnetically coupled via the ferrite core 30 and the ferrite core 40. That is, the ferrite core 30 and the ferrite core 40 link the magnetic flux to the windings 10a to 10c.
[0031]
One end of a primary winding 10a of the switching transformer 70 is connected to a positive electrode of the full-wave rectifier circuit 82. The other end of the primary winding 10a is connected to the drain of the NMOS 83, and the source of the NMOS 83 is connected to one end of the resistor 84. The other end of the resistor 84 is connected to the negative electrode of the full-wave rectifier circuit 82. The negative electrode of the full-wave rectifier circuit 82 is grounded.
[0032]
One end of the secondary winding 10b of the switching transformer 70 is connected to the anode of the diode 85. The cathode of the diode 85 is connected to the output terminal OUT1 and one electrode of the capacitor 86. The other electrode of the capacitor 86 is connected to the output terminal OUT2 and the other end of the secondary winding 10b.
The voltage dividing resistors 87 and 88 are connected in series between the positive and negative electrodes of the full-wave rectifier circuit 82. The voltage dividing resistors 89 and 90 are connected in series between the output terminals OUT1 and OUT2.
[0033]
One end of the tertiary winding 10c of the switching transformer 70 is grounded, and the other end of the tertiary winding 10c is connected to one end of the resistor 91.
The voltage dividing resistors 87 and 88 generate a voltage signal indicating an input voltage input from the full-wave rectifier circuit 82, and a connection point between the voltage dividing resistors 87 and 88 is connected to the control circuit 100. The voltage dividing resistors 89 and 90 generate a voltage signal indicating an output voltage, and a connection point between the voltage dividing resistors 89 and 90 is connected to the control circuit 100.
[0034]
The resistor 84 generates a voltage signal indicating a switching current flowing through the primary winding 10a and the NMOS 83, and a connection point between the source of the NMOS 83 and the resistor 84 is connected to the control circuit 100.
[0035]
The resistor 91 generates a voltage signal indicating that the flyback energy in the tertiary winding 10 c of the switching transformer 70 has been released. The other end of the resistor 91 is connected to the control circuit 100.
[0036]
The control circuit 100 is a circuit that generates a control signal for controlling ON / OFF of the NMOS 83 based on each applied voltage signal. An output terminal of the control circuit 100 is connected to the gate of the NMOS 83.
[0037]
Next, the operation of the switching power supply and the switching transformer 70 of FIG. 5 will be described.
The full-wave rectifier circuit rectifies the AC voltage generated by the AC power supply 81 and converts it into a pulsating voltage. The pulsating voltage is applied to the primary winding 10a of the transformer 70, the NMOS 83, and the resistor 84. The NMOS 83 is turned on when a high-level (hereinafter, referred to as “H”) control signal is applied to the gate from the control circuit 100. The turned-on NMOS 83 allows a switching current to flow through the primary winding 10a and the resistor 84. Energy is accumulated by the switching current flowing through the primary winding 10a. The switching current increases with time. The resistor 84 generates a voltage signal corresponding to the switching current and supplies the voltage signal to the control circuit 100. In the control circuit 100, when the voltage signal given from the resistor 84 reaches the reference value, the control signal transitions to a low level (hereinafter, referred to as “L”). As a result, the NMOS 83 is turned off.
[0038]
When the NMOS 83 is turned off, flyback energy is generated in the secondary winding 10b and the tertiary winding 10c of the switching transformer 70. The flyback energy generated in the secondary winding 10b passes through the diode 85 and is charged in the capacitor 86 as an output voltage. The voltage dividing resistors 89 and 90 supply a voltage signal indicating the output voltage to the control circuit 100.
[0039]
The resistance 84 provides the control circuit 100 with a voltage signal corresponding to the flyback energy. The control circuit 100 detects that the flyback energy generated in the tertiary winding 10c is released based on the voltage signal supplied from the resistor 91, and changes the control signal supplied to the NMOS 83 to “H” again. As a result, the NMOS 83 turns on. As described above, the NMOS 83 is repeatedly turned on and off, and the charged voltage is stored in the capacitor 86. This charging voltage becomes the output voltage.
[0040]
Here, the timing at which the NMOS 83 is turned off is when the voltage signal indicating the increase or decrease of the switching current generated by the resistor 84 reaches the reference value. The control circuit 100 makes its reference value proportional to the voltage signal supplied to the control circuit 100 from the voltage dividing resistors 87 and 88. That is, the reference value is proportional to the input voltage input from the full-wave rectifier circuit 82. Therefore, when the voltage signal indicating the current value of the switching current becomes a voltage proportional to the input voltage, the NMOS 83 is turned off. Thus, the timing at which the NMOS 83 is turned off is adjusted, and the switching current flowing through the primary winding 10a is controlled.
[0041]
Further, the control circuit 100 sets a proportional coefficient to the input voltage of the reference value so that the voltage signal given from the voltage dividing resistors 89 and 90 becomes constant. Further, the control circuit 100 has a function of changing the reference value when the input voltage is low or the load is light in order to realize low power consumption. In this case, the control circuit 100 lengthens the period during which the switching current flows through the primary winding 10a, and reduces the amount of energy stored in the primary winding 10a. That is, the switching frequency of the NMOS 83 is reduced, and the NMOS 83 is turned on and off at an audible frequency, for example.
[0042]
Even if the switching frequency of the NMOS 83 becomes an audible frequency, the gap G between the midfoot portions 34 and 44 of the ferrite core 30 and the ferrite core 40 in the switching transformer 70 is filled with the adhesive 60, so that the low frequency The generation of audible beats is suppressed.
[0043]
On the other hand, the temperature of the switching transformer 70 rises due to external heat or self-heating caused by being driven. Even when the temperature rises, the adhesive 60 filling the gap G between the midfoot 34 of the ferrite core 30 and the midfoot 44 of the ferrite core 40 does not adhere to the bobbin 20. Therefore, since the ferrite core 30, the ferrite core 40, and the bobbin 20 are not integrated by the adhesive 60, even if the bobbin 20 expands, for example, a force that pulls the midfoot portion 34 of the ferrite core 30 in the direction of the gap G. , And the ferrite core 30 is prevented from being damaged and the ferrite core 30 from being cracked.
[0044]
As described above, in the transformer of the present embodiment, even when driven at an audible frequency, it is possible to suppress the generation of an audible sound that is an abnormal sound, and to prevent damage to the ferrite core 30 due to heat.
[0045]
Note that the present invention is not limited to the above embodiment, and various modifications are possible. There are the following modifications.
(1) Each of the ferrite core 30 and the ferrite core 40 has an “E” shape, and the middle foot portion 34 and the middle foot portion 44 have a columnar shape. Such a set of the ferrite core 30 and the ferrite core 40 is called an EER type core, but the ferrite core 30 and the ferrite core 40 are not limited to such shapes. Here, modified examples of the ferrite core 30 and the ferrite core 40 will be described.
[0046]
FIG. 6 is a view showing a modification (part 1) of the ferrite core. FIG. 7 is a view showing a modification (No. 2) of the ferrite core. FIG. 8 is a view showing a modification (No. 3) of the ferrite core. FIG. 9 is a view showing a modification (part 4) of the ferrite core.
[0047]
Instead of the ferrite core 30 and the ferrite core 40, two ferrite cores 101 shown in FIG. 6 may be used. The midfoot portion 101a of the ferrite core 101 is not in the shape of a column but in the shape of a quadrangular prism, and the other portions are the same as the ferrite core 30 or the ferrite core 40. It has two ferrite cores 101 and is called an EE type core.
[0048]
Instead of the ferrite core 30 and the ferrite core 40, a ferrite core 102 and a ferrite core 103 shown in FIG. 7 may be used. The ferrite core 102 has a shape of “E” like the ferrite core 30 or the ferrite core 101, but the ferrite core 103 has a shape of “I”. The central portion of the ferrite core 103 is an opposing portion opposing the midfoot portion 102a of the ferrite core 102. These ferrite cores 102 and 103 are collectively called an EI type core.
[0049]
Instead of the ferrite core 30 and the ferrite core 40, two ferrite cores 104 in FIG. 8 may be used. The outer diameter of the midfoot portion 104a of the ferrite core 104 is larger than the width of the supporting portion 104b in the vicinity thereof, and is called a PQ type core.
[0050]
Instead of the ferrite core 30 and the ferrite core 40, two ferrite cores 105 in FIG. 9 may be used. The outer diameter of the outer leg portion 105a of the ferrite core 105 and the supporting portion 105b supporting the outer leg portion are larger than the columnar middle leg portion 105c. Such a ferrite core is called an RM type core.
[0051]
(2) In the above embodiment, the gap G is provided between the midfoot portions 34 and 44 of the ferrite core 30 and the ferrite core 40. However, the present invention can be applied to a transformer having no gap G when assembled. The same effect as the above embodiment can be expected.
(3) In the above-described embodiment, an example in which the transformer is used as the switching transformer 70 of the power factor correction circuit has been described. However, even when the transformer is incorporated in another switching power supply device and driven at a low frequency, A similar effect is achieved.
[0052]
(4) The filling member that fills the gap is not limited to the epoxy resin adhesive 60, but may be another adhesive. Further, the filling member may be other than the adhesive. If it is assumed that stress will be applied to the ferrite cores 30 and 40 by attaching to the bobbin 20 other than the adhesive, the blocking member 50 prevents the filling member from attaching to the bobbin 20 when the ferrite cores 30 and 40 are supposed to be stressed. A similar effect is achieved. Furthermore, for example, when the filling member is a difficult-to-adhere member such as Teflon (registered trademark), it is predicted that even if an extra filling member on the work is inadvertently attached to the front and back surfaces of the blocking member 50, the effect on the product is not exerted. Therefore, workability is improved.
[0053]
【The invention's effect】
As described above in detail, according to the present invention, generation of abnormal noise can be suppressed while ensuring reliability.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a transformer according to an embodiment of the present invention.
FIG. 2 is a sectional view showing an example of the bobbin in FIG.
FIG. 3 is a front view showing a ferrite core in FIG. 1;
FIG. 4 is a diagram showing a relationship between a ferrite core and a blocking member.
FIG. 5 is a circuit diagram showing a switching power supply device using a transformer.
FIG. 6 is a diagram showing a modification (No. 1) of the ferrite core.
FIG. 7 is a diagram showing a modified example (part 2) of the ferrite core. FIG. 8 is a diagram showing a modified example (part 3) of the ferrite core.
FIG. 9 is a view showing a modification (No. 4) of the ferrite core.
FIG. 10 is a sectional view showing a conventional transformer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Winding 20 Bobbin 21 Body 24 Shaft hole 30, 40 Ferrite core 34, 44 Midfoot part 50 Blocking member 60 Adhesive G Gap

Claims (9)

A bobbin having a body with an axial hole formed in the axial direction,
A winding wound around the body of the bobbin,
A first core configured of a member that transmits a magnetic flux and having a foot inserted into a shaft hole of the bobbin;
A first core inserted into the shaft hole and having a facing portion facing a foot portion of the first core, and linking the magnetic flux to the winding in conjunction with the first core; A second core to intersect,
A filling member filled between the foot portion and the facing portion,
A blocking material that blocks between the filled filling member and the bobbin,
A transformer comprising: A predetermined gap is provided between the facing portion and the foot portion of the first core,
The transformer of claim 1, wherein the filling member fills the gap. The transformer according to claim 1, wherein the filling member is an adhesive. 4. The transformer according to claim 1, wherein the opposing portion of the second core is convex, and opposes the foot within a shaft hole of the bobbin. 5. The transformer according to any one of claims 1 to 4, wherein the blocking member has a cylindrical shape and is inserted into a shaft hole of the bobbin. 5. The method according to claim 1, wherein the blocking member has a film shape and covers a periphery of the filling member filled between a foot portion of the first core and a facing portion of the second core. 6. A transformer according to any one of the preceding claims. A switching element that is turned on and off based on a control signal;
A primary winding through which a switching current flows from a power supply when the switching element is turned on, an arbitrary number of induction windings, a body having an axial hole formed in an axial direction, the primary winding and the body being formed in the body. The first winding is formed of a bobbin on which an induction winding is wound, a member for transmitting magnetic flux, a first core having a foot inserted into a shaft hole of the bobbin, and a member for transmitting magnetic flux. A second core having an opposing portion opposing a foot portion of the core and linking the magnetic flux to the primary winding and the induction winding in conjunction with the first core; A transformer having a filling member filled between the foot portion and the facing portion of the second core, and a blocking member for blocking between the filling member and the bobbin;
Output means for inputting energy stored by the switching current flowing through the primary winding from the induction winding and converting the energy into electric power to be supplied to a load,
Control means for generating the control signal for setting the timing of turning on and off the switching element,
A switching power supply device comprising: A process of inserting a tubular blocking member into the shaft hole of the bobbin in which the winding is wound around the body portion having the shaft hole formed in the axial direction,
A first core having a protruding foot portion formed of a member that transmits magnetic flux, or a second core having a facing portion configured to face the foot portion and configured of a member that transmits magnetic flux; Applying a filling member to one or both of the opposed portions of
The foot of the first core is inserted into the blocking member inserted into the shaft hole, and the foot is opposed to the opposing portion of the second core, and the opposing foot and the opposing portion When the filling member protrudes from between, a process of attaching the protruding filling member to the blocking member,
A method for manufacturing a transformer, comprising: The filling member is an adhesive,
The method for manufacturing a transformer according to claim 8, further comprising, after the foot portion and the facing portion are opposed to each other, a process of curing the adhesive.

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