JP2008004905A - Transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transformer capable of improving a magnetic shielding property against a coil and preventing a malfunction as a corner sensor, and reducing a material cost and the number of processes. <P>SOLUTION: In order to achieve the aforementioned object, the present invention provides: a transformer 31 including a shield case 20 having screw parts 24 on two inner side surfaces opposed to each other; and a cylindrical movable core 29 having a screw 21 screwed into each screw part 24 of the shield case 20 on an outer peripheral surface, with a larger inner diameter than the diameter of a coil 14 capable of containing the coil 14, and disposed to cover the outer periphery of the coil 14, with a lower end portion advancing/retreating in the shield case 20 while being slidably in contact with the lower end portion of a core 28, to make an inductance of the coil 14 variable. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transformer, and more particularly to a transformer of the type that is surface-mounted on an electronic circuit board.

  Conventionally, such a surface mount type transformer has a structure as shown in, for example, Patent Document 1 and a structure as shown in FIGS. 6 and 7.

6 and 7 is provided with a plurality of lead terminals 3, 3,... Projecting horizontally from the base 2 on the side surface of the insulating base 2. The outer side is covered with the square shield case 4. Each winding lead portion of the coil wound around the outer peripheral surface of the coil bobbin (not shown) is entangled with the root portions 3a of the corresponding lead terminals 3, 3,... It is fixed. Then, the tip 3b of each lead terminal 3, 3,... Is bent downward in an L shape and soldered to the electronic circuit board 6 as shown in FIG. The surface-mount transformer 1 is attached to the mounting surface of the electronic circuit board 6.
Japanese Patent Laid-Open No. 10-135045 (FIGS. 4 and 5).

  In the surface mount type transformer described in Patent Document 1 and the surface mount type transformer having the structure as shown in FIGS. 6 and 7, a magnetic shield is generally intended for the coil with a single square shield case. is there.

  By the way, a transformer used as a corner sensor is required to be able to sufficiently prevent the malfunction as the corner sensor by sufficiently shielding the influence of the external disturbance magnetic flux. For this reason, as described above, in the case where the magnetic shield with respect to the coil is achieved only with the single square shield case, there is a possibility that the corner sensor may malfunction.

  Further, this type of component is required to be able to reduce the cost as much as possible together with the malfunction prevention characteristics as described above.

  Therefore, there is a technical problem to be solved in order to improve the magnetic shielding property against the coil to prevent malfunction as a corner sensor and to reduce the material cost and man-hour, and the present invention solves this problem. The purpose is to do.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is provided with a drum-shaped core, a coil wound around the outer peripheral surface of the core, and a lower end of the core. In a transformer comprising an insulating base and a lead terminal projecting horizontally from the base, the lead portion of the coil being entangled with the lead terminal. A shield case having a double structure including an inner shield case portion having a threaded portion and an outer shield case portion externally fitted to the inner shield case portion, and a diameter of the coil to accommodate the coil It has a large inner diameter, and the outer peripheral surface has a screw that engages with the screw portion of the inner shield case portion so as to cover the outer periphery of the coil. Providing a transformer having a cylindrical movable core for varying the scan.

  According to this configuration, since the shield case has a double structure of the inner shield case portion and the outer shield case portion, a good magnetic shield for the coil can be obtained, and malfunction of the corner sensor can be prevented.

  According to a second aspect of the present invention, there is provided a drum-shaped core, a coil wound around the outer peripheral surface of the core, an insulating base provided at the lower end of the core, and a horizontal projection from the base In a transformer comprising a lead terminal that is connected, and a lead part of the coil being entangled with the lead terminal, a shield case having a thread part on each of two opposing inner surfaces, and the coil for receiving the coil The inner diameter is larger than the diameter of the shield case, and the outer peripheral surface has a screw threadedly engaged with the screw portion of the shield case so as to cover the outer periphery of the coil, while the lower end portion is in sliding contact with the lower end portion of the core. There is provided a transformer having a cylindrical movable core that moves forward and backward in the shield case to change the inductance of the coil.

  According to this configuration, the lower end portion of the movable core moves between the lower end portion of the movable core and the lower end portion of the movable core by moving back and forth in the shield case while being in sliding contact with the lower end portion of the drum core. The magnetic flux leakage is greatly reduced due to the closed magnetic flux structure, and a good magnetic shield for the coil can be obtained without the shield case having a double structure as in the first aspect of the present invention.

  According to the first aspect of the present invention, there is provided a double-structure shield comprising an inner shield case portion having a threaded portion on each of two opposing inner side surfaces and an outer shield case portion externally fitted to the inner shield case portion. A case and an inner diameter larger than the diameter of the coil to accommodate the coil, and an outer peripheral surface is provided so as to cover the outer periphery of the coil with a screw that engages with a screw portion of the inner shield case portion. Since the cylindrical movable core that moves back and forth in the shield case and changes the inductance of the coil is provided, a good magnetic shield for the coil can be obtained, so that malfunction as a corner sensor can be prevented. There is an advantage.

  According to the second aspect of the present invention, there is provided a shield case having a thread portion on each of two opposed inner surfaces, an inner diameter larger than the diameter of the coil to accommodate the coil, and a thread portion of the shield case on the outer peripheral surface. A cylindrical movable member that has a screw to be screwed and covers the outer periphery of the coil, and whose lower end portion is in sliding contact with the lower end portion of the core while moving forward and backward in the shield case to change the inductance of the coil. Because it has a core, even if the shield case does not have a double structure, a good magnetic shield for the coil can be obtained, preventing malfunction as a corner sensor, and reducing material costs and man-hours. There is an advantage that can be.

  In order to prevent the malfunction as a corner sensor by improving the magnetic shielding property against the coil, and to achieve the purpose of reducing the material cost and man-hour, the drum-shaped core and the outer periphery of the core were wound. A transformer comprising a coil, an insulating base provided at the lower end of the core, and a lead terminal protruding in a horizontal direction from the base, the lead portion of the coil being entangled with the lead terminal A shield case having a threaded portion on each of two opposing inner surfaces, and an inner diameter larger than the diameter of the coil to accommodate the coil, and a screw threadedly engaged with the threaded portion of the shield case on the outer peripheral surface. The coil has an outer periphery, and is disposed so as to cover the outer periphery of the coil. The lower end of the coil slides forward and backward in the shield case while being in sliding contact with the lower end of the core, thereby varying the inductance of the coil. It was achieved by and a cylindrical movable core.

Hereinafter, the transformer of the present invention will be described with reference to preferred embodiments. 1 to 3 show a transformer according to the present invention. FIG. 1 is a top view, FIG. 2 is a partially cut-away side sectional view, and FIG. 3 is a bottom view.

  1 to 3, the transformer 11 includes an insulating base 12, a fixed core 13, a coil 14, a movable core 15, and a square shield case 16.

  The base 12 is formed in a substantially flat quadrangular shape with a thermoplastic insulating resin such as a liquid crystal polymer. Further, at the time of molding, the fixed core mounting hole 17 is provided on the upper surface, and the four lead terminals 18, 18,... Are inserted so that the two lead terminals 18, 18 are horizontally directed outward from the left and right side surfaces. It is provided in a protruding state.

  The lead terminal 18 is phosphor bronze, and as shown in FIG. 4, one end side of the terminal portion 18a and the terminal processing portion 18b extending in parallel to each other in the same direction, and the terminal portion 18a and the terminal processing portion 18b. Are integrally formed with a connecting portion 18c that connects the two to each other, and is formed in a substantially U-shape. Further, the substantially intermediate portion 18d of the connecting portion 18c is bent in the vertical direction, and the positions of the terminal portion 18a and the terminal processing portion 18b are shifted up and down by this bending. This deviation amount is an amount that can sufficiently absorb the binding height of the binding portion 14a and the winding loosening portion 14b of the coil 14, which will be described later, and the transformer 11 is mounted on the electronic circuit board 19 as shown in FIG. This is the amount that can prevent the binding portion 14a and the loosened winding portion 14b from coming into contact with the board mounting surface.

  As shown in FIGS. 1 and 3, each lead terminal 18 has the terminal portion 18a on the outside, the terminal processing portion 18b on the inside, and as shown in FIG. 2, the terminal portion 18a is connected to the terminal processing portion 18b. In the state where the terminal portion 18a is disposed at the lowermost end portion of the base 12 and the lower surface of the terminal portion 18a is exposed at the bottom surface of the base 12, the terminal portions 18a and the terminal processing portions 18b are The base 12 is provided so as to protrude from the side surface of the base 12 in the horizontal direction.

  The fixed core 13 is a nickel-based ferrite core and is formed in a drum shape. As shown in FIG. 2, the protruding portion 13a on the lower end side is fitted into the fixed core mounting hole 17 of the base 12 and bonded. By being fixed to the base 12 with an agent, it is attached in a state of standing on the base 12. The fixed core 13 has a function of a winding frame. The coil 14 is formed on the outer peripheral surface of the fixed core 13 by winding, and the coil 14 is drawn out from the coil 14. The four lead portions are entangled with the terminal processing portions 18b of the corresponding lead terminals 18 and soldered to the terminal processing portions 18b.

  The movable core 15 is a nickel-based ferrite core, and has a cup-shaped cylindrical body having an inner diameter larger than the diameter of the coil 14, closed on the upper surface, and opened on the lower surface side to accommodate the coil 14 together with the fixed core 13. The screw 21 is formed on the outer peripheral surface. Further, as shown in FIG. 1, a cross groove 22 is provided on the upper surface.

  The rectangular shield case 16 is made of a copper alloy, and is a rectangular column-shaped cylinder whose upper surface is closed and whose lower surface is opened. In order to accommodate the movable core 15 therein, the square shield case 16 has a diameter larger than that of the movable core 15. Is also formed with a large inner diameter. Further, a round hole 23 for applying a tool such as a screwdriver to the cross groove 22 of the movable core 15 is provided on the upper surface. The rectangular shield case 16 has a double structure composed of an inner shield case portion 16A and an outer shield case portion 16B (also referred to as a short ring) fitted outside the inner shield case portion 16A. It is made as one shield case.

  Further, on the left and right inner surfaces of the inner shield case portion 16A facing each other, screw portions 24 and 24 to be screwed with the screw 21 of the movable core 15 are formed.

  The transformer 11 according to the present embodiment formed as described above is assembled as follows. First, as shown in FIG. 2, the movable core 15 is inserted into the rectangular shield case 16 from its lower opening. Since the movable core 15 has a screw 21 formed on the outer peripheral surface, when the movable core 15 is inserted while being rotated, the movable core 15 meshes with the screw portions 24 and 24 provided on the inner shield case portion 16A. 15 is held in the square shield case 16.

  Next, a rectangular shield case 16 is placed in the movable core 15 to accommodate the coil 14 and the fixed core 13 from the lower opening thereof, and is provided at the lower end of the outer shield case portion 16B as shown in FIG. When the engaging claw 25 is engaged with the engaging groove 26 provided on the side surface of the base 12, the rectangular shield case 16 is fixed to the base 12 and the assembly is completed.

  The thus configured transformer 11 inserts a tool such as a Phillips screwdriver from a round hole 23 provided on the upper surface of the rectangular shield case 16 and engages the tip of the tool with the cross groove 22 of the movable core 15. When the movable core 15 is rotated, the movable core 15 advances and retreats in the vertical direction, and a desired inductance is obtained.

  Further, when mounting on the electronic circuit board 19, if it is arranged on the electronic circuit board 19, the terminal part 18 a comes into contact with a conductor part (not shown) of the electronic circuit board 19, and further processing such as reflow soldering is performed. The terminal portion 18a is soldered to the conductor portion and attached to the mounting surface of the electronic circuit board 19.

  As described above, according to the transformer 11 according to the first embodiment, the shield case 16 has the double structure of the inner shield case portion 16A and the outer shield case portion (short ring) 16B. Therefore, it is possible to prevent a malfunction as a corner sensor.

  Table 1 shows a test result example of a noise test showing the magnetic shielding effect. In the table, “with short ring” means that the shield case 16 has a double structure of the inner shield case portion 16A and the outer shield case portion 16B, and “without short ring” means that the shield case 16 is on the inner side. A case where only the shield case portion 16A has a single structure is shown.

  The output voltage in the column of the output voltage ratio indicates an output voltage due to noise, and the output voltage with a short ring is expressed as a ratio on the basis of the output voltage without a short ring. It shows that the lower the value of the output voltage is, the more effective the magnetic shielding effect is. The rate of change (%) is the ratio of the output voltage when “with short ring” to the output voltage when “without short ring” as described above.

  From the results shown in the table, when the shield case 16 has a double structure, the magnetic shield effect is improved by about 35% in terms of noise output voltage compared to a single structure having only the shield case portion 16A. .

また、基板実装面に半田付けされる端子部１８ａと、コイル１４の絡げ部１４ａ及び巻き緩み部１４ｂが形成される端末処理部１８ｂとを分離させた構造にしているので、巻線切断時の巻線張力は、端子部１８ａに直接加わることがなく、コイル１４のリード部の絡げ処理時に、端子部１８ａに不要な曲りが生じない。さらに、端子部１８ａ側からの外力も端末処理部１８ｂには直接加わらない。したがって、端子部１８ａ側に変形が生じても、コイル１４の絡げ部１４ａ、巻き緩み部１４ｂには不要な力が生じない。仮に端末処理部１８ｂに外力が加わっても巻き緩み部１４ｂによりリード部に緩み構造があるため、外力が加わらず疲労断線しない構造である。

In addition, since the terminal portion 18a soldered to the board mounting surface and the terminal processing portion 18b in which the binding portion 14a and the winding loose portion 14b of the coil 14 are formed are separated, the winding is cut. No winding tension is applied directly to the terminal portion 18a, and unnecessary bending does not occur in the terminal portion 18a during the binding process of the lead portion of the coil 14. Furthermore, the external force from the terminal part 18a side is not directly applied to the terminal processing part 18b. Therefore, even if deformation occurs on the terminal portion 18a side, unnecessary force does not occur in the binding portion 14a and the loosened portion 14b of the coil 14. Even if an external force is applied to the terminal processing portion 18b, the lead portion is loosened by the winding loose portion 14b, so that the external force is not applied and the structure is not broken.

  In addition, a desired inductance can be obtained by moving the movable core 15 forward and backward while rotating in the rectangular shield case 16.

  FIG. 5 is a partially cut-away side sectional view of the transformer according to the present embodiment. In the transformer 31 of the present embodiment, the shield case 20 is configured by only one sheet corresponding to the inner shield case portion in the first embodiment. Further, the height of the base 27 is formed slightly higher than the height of the base in the first embodiment, and the lower flange portion 28a of the drum-shaped fixed core 28 is more than the same flange portion in the first embodiment. Is slightly larger in diameter.

  Furthermore, the movable core 29 is formed in a shape extending slightly longer below the movable core in the first embodiment, and the inner peripheral surface of the portion extending long downward is a lower flange portion of the fixed core 28. The lower end portion of the movable core 29 and the lower flange portion 28a of the fixed core 28 are opposed to each other so as not to contact the outer peripheral surface of the 28a.

  When the movable core 29 is rotated via the screw portions 21, 24, the movable core 29 has its lower end portion in sliding contact with the outer peripheral surface of the lower flange portion 28 a of the fixed core 28. The case 20 is advanced and retracted in the vertical direction. The movable width of the movable core 29 in the vertical direction is within a range in which the lower end portion of the movable core 29 is always in sliding contact with the outer peripheral surface of the lower flange portion 28a of the fixed core 28, that is, within the vertical width of the flange portion 28a. Stopped.

  Therefore, between the lower flange portion 28a of the fixed core 28 and the lower end portion of the movable core 29, a normally closed magnetic flux structure is formed, and the magnetic flux leakage is greatly reduced. As a result, a good magnetic shield almost equivalent to the double-structured shield case is obtained.

  As described above, when the movable width in the vertical direction of the movable core 29 is narrowed within the vertical width of the flange portion 28a, the variable range of the inductance value of the coil 14 is narrowed. Since variations in characteristics are extremely small, even if the variable range of the inductance value is narrow, it can be sufficiently tolerated as a product.

As described above, according to the transformer 31 according to the second embodiment, a good magnetic shield for the coil 14 can be obtained and the malfunction as a corner sensor can be prevented without the shield case 20 having a double structure. In addition, material costs and man-hours can be reduced. Furthermore, quality anxiety due to the short ring dropping off can be eliminated.

  In addition, in the structure of the second embodiment, if an outer shield case portion as in the first embodiment is further attached and the shield case is made to have a double structure, a magnetic shield characteristic extremely strong against external disturbance magnetic flux can be obtained. As a result, it is possible to significantly improve characteristics that are difficult to realize at present.

  Further, the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 is a top view of a transformer according to Embodiment 1 of the present invention. The partially cut side sectional view of the transformer. The bottom view of a transformer same as the above. The expansion perspective view of the lead terminal currently used with a transformer same as the above. FIG. 6 is a partially cut-away side cross-sectional view of a transformer according to Embodiment 2 of the present invention. The top view which shows an example of the conventional surface mount type | mold transformer. The side view of the conventional surface mount type transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface mount type transformer 2 Insulation base 3 Lead terminal 4 Rectangular shield case 5 Binding part 6 Electronic circuit board 11 Transformer 12 Base 13 Fixed core 13a Protrusion part 14 Coil 14a Binding part 14b Winding loose part 15 Movable core 16 Square shield case 16A Inner shield case part 16B Outer shield case part 17 Fixed core mounting hole 18 Lead terminal 18a Terminal part 18b Terminal processing part 18c Connection part 18d Intermediate part 19 Electronic circuit board 20 Shield case 21 Screw 22 Cross groove 23 Round Hole 24 Threaded portion 25 Locking claw 26 Locking groove 27 Base 28 Fixed core 28a Lower flange 29 Movable core 31 Transformer

Claims (2)

A drum-shaped core, a coil wound around the outer peripheral surface of the core, an insulating base provided at the lower end of the core, and a lead terminal projecting horizontally from the base In the transformer formed by tying the lead portion of the coil to the lead terminal,
A shield case having a double structure including an inner shield case portion having a screw portion on each of two opposing inner side surfaces and an outer shield case portion externally fitted to the inner shield case portion, and the coil are accommodated Therefore, the inner diameter of the coil is larger than the diameter of the coil, and the outer peripheral surface is provided with a screw that engages with the screw portion of the inner shield case portion so as to cover the outer periphery of the coil. A transformer having a cylindrical movable core that extends and changes an inductance of the coil. A drum-shaped core, a coil wound around the outer peripheral surface of the core, an insulating base provided at the lower end of the core, and a lead terminal projecting horizontally from the base In the transformer formed by tying the lead portion of the coil to the lead terminal,
A shield case having a thread portion on each of two opposing inner surfaces, an inner diameter larger than the diameter of the coil to accommodate the coil, and an outer peripheral surface having a screw that engages with the thread portion of the shield case And a cylindrical movable core that is disposed so as to cover the outer periphery of the coil, and whose lower end portion is in sliding contact with the lower end portion of the core and advances and retracts in the shield case to vary the inductance of the coil. Transformer.

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