JPH0724622Y2 - Electromagnetic pickup sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electromagnetic pickup sensor.

<Prior Art> Conventionally, for example, in order to detect the top dead center position of a cylinder and perform ignition timing control, the crank angle can be determined by detecting a change in magnetic flux due to rotation of a disk connected to a crank shaft of an internal combustion engine. An electromagnetic pickup type angle detection device for detecting is known (see Japanese Patent Laid-Open No. 60-178975).

In FIG. 4 showing the structure of a conventional electromagnetic pickup sensor, a core top 2 formed into a stepped shape with a small diameter and a large diameter.
And a magnetized step by joining so that a cylindrical magnet 3 having substantially the same diameter as the core bottom 4 is sandwiched between the large diameter portion of the core top 2 and the cylindrical core bottom 4 having substantially the same diameter. The shaped core 1 is formed, and the small diameter end of the core 1 is the tip and the large diameter end is the base end. The bobbin 5 is provided with a through hole having a shape corresponding to the stepped core 1 at the center, and the core 1 is held by this through hole and fixed by caulking the corner 5a of the bobbin 5 with heat. Further, it is sealed with resin 6. The coil 7 is arranged on the outer periphery of the tip portion of the core 1 via the bobbin 5 and fixed by an adhesive material 9.
A voltage is generated by the change in the magnetic flux of the core 1. The terminal of the coil 7 is connected to the terminal 8 by spot welding or the like,
The voltage generated in the coil 7 is output via the terminal 8. The cap 11 has a U-shaped cross section, and the core 1
The coil 7 is covered from the tip end side of and the open end side is crimped and fixed to the bobbin 5. An O-ring 10 as a sealing member is inserted in the groove 5b on the outer periphery of the bobbin 5 near the opening end side of the cap 11 to seal the gap between the bobbin 5 and the cap 11. In the fixing hole 5c of the bobbin 5, a bush 12 which is a cushioning material for fixing is embedded.

The output end of the terminal 8 of this electromagnetic pickup sensor is connected to a detecting device 14 in which a resistance r is inserted in parallel as shown in FIG. 3, and is connected to, for example, a crankshaft provided with an uneven gear cutting plate on its circumference. The electromagnetic pickup is set so that the core 1 is located near the signal disc plate 13 that rotates in conjunction with the cap 11 and the signal disc plate 13 rotates. The magnetic flux of 1 changes, and the coil 7
A voltage is generated in the detector, and the generated voltage is detected by the detection device 14.

<Problems to be solved by the invention> By the way, in the conventional electromagnetic pickup sensor, the core 1 is fixed by crimping the corners 5a of the bobbin 5, so that heat of the engine or the like is transferred to the thermal creep. Occurs, and a gap 15 is created between the bobbin 5 and the core 1. Therefore, when the vibration of the engine or the like is transmitted to the main body of the electromagnetic pickup sensor, the core 1 vibrates slightly,
As shown in FIG. 5, self-noise due to microvibration of the core 1 is superimposed on the output voltage of the coil 7, so that the performance is deteriorated. Further, since there is no escape path for air in this structure, the cap 11 cannot be inserted smoothly during the process of tightening the cap 11 during manufacturing, and the O-ring 10 may be damaged, resulting in poor workability.

The present invention has been made in view of such conventional problems, and an object thereof is to provide an electromagnetic pickup sensor that does not generate self-noise and has good workability in the manufacturing process.

<Means for Solving the Problems> Therefore, in the present invention, a magnetic core having a stepped shape with a small diameter at the tip and a large diameter at the base and a penetrating shape having a shape corresponding to the shape of the core are provided. A bobbin that has a hole and holds the core in the through hole and fixes the core base end side by thermal crimping, and a voltage is generated due to a change in the magnetic flux of the core that is arranged on the outer periphery of the tip end portion of the core through the bobbin. The coil that is generated,
A cap having a U-shaped cross-section that is capped from the tip side of the core and covers the coil and is fixed to the bobbin by crimping the opening end side, and between the bobbin and the cap provided on the outer circumference of the bobbin near the cap opening end side. In the electromagnetic pickup sensor for converting the magnetic flux change of the core into the voltage of the coil by providing a seal member for sealing the gap of, a resin having an adhesive property on one of the outer wall of the core and the through hole wall of the bobbin. A groove for filling is provided substantially from the tip end side to the base end side, and the resin is filled from the tip end side to the base end side of the groove,
The base end of the core was covered with resin.

<Operation> According to the above configuration, a groove is formed from approximately the core tip side to the base end side of either the core outer periphery or the bobbin through hole wall, and the adhesiveness is increased from the core tip side of the groove to the base end side. Is filled with the resin, and the base of the core is covered with the resin. Therefore, the core is firmly fixed to the bobbin by the adhesive force of the resin,
No gap can be created by heat. Therefore, microvibration of the core does not occur, and self-noise due to microvibration of the core does not occur. Further, in the process of tightening the cap during manufacturing, if the cap is inserted before the resin is filled, the groove for resin filling serves as an escape path for air, so that the cap can be smoothly inserted.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.
The same elements as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1 showing the present embodiment, a groove 20 is provided in a through hole wall of a bobbin 25 from substantially the core tip side to the base end side.
The corner 25a of 25 is cut only in the groove 20. The groove 20 may be provided on the outer circumference of the core 1.

In the manufacturing process, the cap 11 is tightened by thermally crimping the corner portion 25a of the bobbin 25, and the O-ring 10 is attached to the groove 25b of the bobbin 25.
Done after inserting into. Since the corner portion 25a is cut only in the groove 20, even if the corner portion 25a is thermally caulked
Can't be blocked. When the cap 11 is covered on the tip side of the core 1, the groove 20 serves as an escape path for air, so that the cap 11 can be smoothly inserted. Then put on the cap 11,
The open end of the cap 11 is crimped and fixed to the bobbin 25, and then the groove 20 is filled with resin from the core front end side to the base end side, and the core base end portion is covered with the resin. As the resin, for example, an epoxy resin having strong adhesiveness and curability is used. The resin is filled in the groove 20, and when cured, the resin is filled from the tip end side to the base end side, and the core 1 is firmly fixed to the bobbin 25 by the adhesive force of the resin covering the core base end side.

According to this structure, the core 1 is firmly fixed to the bobbin 25 by the adhesive force of the resin filling the groove 20 from the base end side to the tip end side and covering the core base end portion, and the gap is formed by thermal creep or the like. It never happens. Therefore, even when it is used as a crank angle sensor of a vehicle, for example, the micro-vibration of the core 1 does not occur due to the vibration of the engine, and the self-noise does not occur due to the micro-vibration. Therefore, as shown in FIG. Is obtained and the performance is improved. Also, in the process of tightening the cap 11 at the time of manufacturing, if the cap 11 is inserted before the resin is filled, the groove 20 provides an escape path for air, and the insertion can be smoothly performed.
Workability is improved without damaging the.

In this embodiment, epoxy resin is used for the resin 6,
Other resins may be used as long as they have strong adhesiveness and curability.

<Effects of the Invention> As described above, according to the present invention, a groove is formed from the core tip side to the base end side of either the core outer periphery or the bobbin through hole wall, and the groove is formed from the core tip side. Since the resin is filled up to the base end side and the core base end side is covered with the resin, the core is firmly fixed to the bobbin by the adhesive force of the resin, and a gap is not formed by thermal creep or the like. Therefore, the microvibration of the core does not occur and the self-noise due to the microvibration of the core does not occur, so that an accurate output voltage can be obtained and the performance is improved. Further, in the process of tightening the cap, this groove serves as an escape path for the air, so that the cap can be smoothly inserted and the workability is improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is an output characteristic diagram of FIG. 3, FIG. 3 is an explanatory diagram of an electromagnetic pickup type angle detection device, FIG. 4 is a conventional sectional view, and FIG. 5 is an output characteristic diagram of FIG. 1 ... Core, 6 ... Resin, 7 ... Coil, 10 ... O-ring, 11 ... Cap, 20 ... Groove, 25 ... Bobbin

Claims (1)

[Scope of utility model registration request] 1. A magnetic core having a stepped shape with a small diameter at the tip and a large diameter at the base, and a through hole having a shape corresponding to the shape of the core. A core fixed to the core base end side by thermal crimping, a coil disposed on the outer periphery of the tip end portion of the core via the bobbin, and a voltage is generated by a change in magnetic flux of the core; A cap having a U-shaped cross section which is capped and covers the coil and is fixed to the bobbin by crimping the opening end side, and a gap provided between the bobbin and the cap provided on the outer circumference of the bobbin near the cap opening end side to seal the gap. A seal member is provided, and in an electromagnetic pickup sensor for converting a magnetic flux change of the core into a voltage of the coil, a groove for filling a resin having an adhesive property is provided on one of the outer wall of the core and the wall of the through hole of the bobbin. Abbreviation Provided from the A distal end to the proximal end side, an electromagnetic pickup sensor that the resin was packed toward the proximal end side from the core front end side of the groove, the core proximal portion, characterized by being configured to cover a resin.