JPH0686080U - Current detector - Google Patents

Abstract

(57) [Abstract] [Purpose] In the conventional current detection device of this type, since the core is fixed by being embedded in the case by integral molding, the temperature coefficient of the core member and the case member is Deformation was caused by the difference, which caused drift and reduced measurement accuracy. According to the present invention, the core 2 is provided with an apron-like mounting portion 5 formed by integrally molding a resin member so as to straddle the gap portion. The inner diameter of the core 2 and the mounting portion 5 form a case 3
Is fixed to the core 3, and the magnetoelectric conversion element 4 is arranged in the gap portion 2a by fastening the mounting portion 5 to the case 3 together. The structure for fixing 2 to the case 3 is the mounting portion 5 provided only in the gap portion 2a, thereby reducing the total amount of resin integrated in the core 2,
To solve the problem by reducing the amount of deformation of the core due to the difference in the coefficient of thermal expansion when the external temperature changes.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a current detection device used when current is measured without disconnecting an electric circuit, which has a relatively high current, such as measurement of a current of a drive motor of an electric vehicle. The details are related to the configuration.

[0002]

[Prior art]

 FIG. 4 shows an example of the configuration of a conventional current detecting device 90 of this kind. A core formed of a silicon steel plate or the like so that the whole shape is substantially square shape, and a gap portion 91a is provided on one side. 91 is integrally formed with a case 92 made of a thermoplastic resin by insert molding or the like, and is fixed so as to be embedded in the case 92.

Further, a magnetoelectric conversion element 93 such as a Hall element for detecting magnetic flux in the core 91 is attached to a printed circuit board 94 and then screwed in a case attachment hole 94a provided in the printed circuit board 94. It is fixed to the case 92 by the above-mentioned method and faces the gap portion 91a.

[0004]

[Problems to be solved by the device]

 However, in the above-described conventional configuration, most of the core 91 except for the gap portion 91a is embedded in the case 92, so that, for example, a metal member on which the core 91 is formed, Due to the difference in thermal expansion coefficient between the case 92 and the resin member in which the case 92 is formed, when the external temperature changes, the gap of the gap portion 91a changes.

This change in the distance causes a great change in the intensity of the magnetic flux in the gap portion 91a. For example, even when the current to be measured is the same, the output from the magnetoelectric conversion element 93 changes due to the change in ambient temperature. This causes so-called drift, which causes a problem of impairing the accuracy of the current detection device 90, and it has been a problem to solve this problem.

[0006]

[Means for Solving the Problems]

 As a concrete means for solving the above-mentioned conventional problems, the present invention provides a magnetoelectric conversion element in the gap portion of a core fixed in a case with a gap portion provided on one side of a substantially square shape. In the current detecting device that detects the change in magnetic flux generated in the core by the current, an apron-shaped mounting part is provided in the gap part so as to straddle the gap part by integrally molding a resin member, and the core is The core is fixed to the case by the inner diameter of the core and the mounting part, and the magnetoelectric conversion element is arranged in the gap part by joint tightening when mounting the mounting part to the case. It is an object of the present invention to solve the problems by providing a current detection device characterized by the above.

[0007]

【Example】

 Next, the present invention will be described in detail based on an embodiment shown in the drawings. Reference numeral 1 in FIGS. 1 and 2 is a current detecting device according to the present invention. The current detecting device 1 employs a core 2 in which a gap portion 2a is provided on one side having a substantially square shape. The core 2 is fixed to the case 3, and the gap 2a is configured to face the magnetoelectric conversion element 4 such as a Hall element, as in the conventional example.

Here, in the present invention, when fixing the core 2 to the case 3, the mounting portion 5 is provided on the core 2 side, and the core 2 is mounted to the case 3 via the mounting portion 5. At the same time, the arrangement of the magnetoelectric conversion element 4 in the gap portion 2a is also performed by using the attachment portion 5.

To describe the above configuration in more detail below, first, the mounting portion 5 is provided in an apron shape protruding outward so as to straddle the gap portion 2 a provided in the core 2. In providing the mounting portion 5, the core 2 is integrally formed by means such as insert molding of a resin member.

At this time, the mounting portion 5 is provided with a pair of case mounting holes 5a for mounting on the case 3, and a concave portion 5b is provided from the back side of the case mounting hole 5a to form the meat. The mounting portion 5 is removed, and the mounting portion 5 is formed to be thin as a whole. The mounting portion 5 serves as a reference for the mounting position during the work for mounting the case 3 described later.

The mounting portion 5 and the case mounting hole 5a are also used for mounting the magnetoelectric conversion element 4, and as described in the conventional example, the printed circuit board 6 on which the magnetoelectric conversion element 4 is mounted is also mounted. An element mounting hole 6a is provided corresponding to the case mounting hole 5a, and a pair of positioning bosses 5c are provided in the mounting portion 5 so as to sandwich the gap portion 2a, and are provided on the printed circuit board 6. With the positioning hole 6b, the magnetoelectric conversion element 4 is set at a predetermined position of the gap 2a.

On the other hand, the case 3 is formed of a resin member in, for example, a box shape. At this time, the cylindrical portion 3 a fitted to the inner diameter of the core 2 is provided to measure A protrusion 3b that is provided for penetrating the core 2 such as a constant wire and that fits into the recess 5b of the mounting portion 5 is provided. In addition, the protrusion 3b has a screw hole 3c corresponding to the case mounting hole 5a. It is supposed to be provided.

At this time, the fitting of the inner diameter of the core 2 with the tubular portion 3a of the case 3 and the fitting of the convex portion 3b of the case 3 with the concave portion 5b of the mounting portion 5 are referred to as the core 2 The case 3 and the case 3 do not need to be tightly fitted to each other so as not to cause looseness at all, and both may be loosely fitted with an appropriate clearance.

When assembling the current detecting device 1 of the present invention having the above structure, the inner diameter of the core 2 and the cylindrical portion 3 a of the case 3, the convex portion 3 b of the case 3 and the concave portion 5 b of the mounting portion 5 are arranged. By fitting and, the case 3 and the mounting portion 5, in other words, the core 2 and the case 3 are tentatively assembled at substantially predetermined positions.

At the same time, if the positioning boss 5c of the mounting portion 5 and the positioning hole 6b of the printed circuit board 6 are fitted together, the mounting portion 5 and the printed circuit board 6, in other words, the core 2 and the magnetoelectric conversion element 4 are connected. Positioning is also performed, and in the state where this temporary assembly is performed, the screw hole 3c, the case mounting hole 5a, and the element mounting hole 6a are substantially aligned.

Therefore, if the screw 7 penetrates the case mounting hole 5a and the element mounting hole 6a and is fastened to the screw hole 3c, the core 2 and the printed circuit board 6 are fixed to the case 3 via the mounting portion 5. At this time, mutual positions are also set as predetermined positions.

Next, the operation and effect of the present invention having the above configuration will be described. In the present invention, the mounting portion 5 for fixing the core 2 to the case 3 is limited to the gap portion 2a, thereby reducing the total amount of resin integrated in the core 2 and changing the external temperature. The amount of deformation of the core 2 due to the difference in the temperature expansion coefficient is reduced.

At the same time, since the printed circuit board 6 is mounted using the mounting portion 5, the printed circuit board 6 is mounted in the vicinity of the gap 2a. This means that the magnetoelectric conversion element 4 is mounted near the gap portion 2a, the positions of the gap portion 2a and the magnetoelectric conversion element 4 are set accurately, and the external temperature The effect of is also small.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the mounting portion 8 covers the end surface 2b of the gap portion 2a of the core 2 facing each other with a thin film cover portion 8d. And is suitable for, for example, a wound plate-shaped core 2 called a cut core. The mounting portion 8 is also provided with a case mounting hole, a recess and a positioning boss, as in the previous embodiment.

When the core 2 is formed by winding a thin plate, the gap portion 2 a is formed by machining after the winding process is completed and impregnation with varnish or the like is performed. Become. Therefore, the metal surface is exposed at the end surface 2b of the gap portion 2a, and there is a high possibility of rusting afterwards.

In this embodiment, the rusting is prevented by integrally forming and covering the cover portion 8d by utilizing the time when the mounting portion 8 is formed on the end surface 2b of the gap portion 2a. Therefore, the anticorrosion treatment required for the end surface 2b of the gap portion 2a becomes unnecessary. The operational effects other than those described above are the same as those of the previous embodiment, and thus detailed description thereof is omitted here.

[0022]

[Effect of device]

 As described above, according to the present invention, the core is provided with the apron-like mounting portion by integrally molding the resin member so as to straddle the gap portion, and is fixed to the case by the inner diameter of the core and the mounting portion. In addition, the magnetoelectric conversion element is arranged in the gap by co-tightening when the mounting part is mounted in the case. For this purpose, the mounting part is provided only in the gap part, which reduces the total amount of resin integrated in the core and reduces the deformation of the core due to the difference in the coefficient of thermal expansion when the external temperature changes. At the same time, it has an extremely excellent effect in reducing the drift and improving the measurement accuracy.

In addition, since the magnetoelectric conversion element is also attached using the attachment portion, the electromagnetism conversion element is attached in the vicinity of the gap portion, and the gap portion and the magnetoelectric conversion element are attached. The position is set accurately, for example, variations among individuals are reduced, and it has an excellent effect on performance improvement.Furthermore, the cover part is integrally formed at the time of forming the mounting part on the end face of the gap part. By covering it, the anticorrosion treatment can be abolished and the number of processes can be reduced, resulting in excellent productivity improvement.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a current detecting device according to the present invention in a partially disassembled state.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view showing the main part of another embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional example.

[Explanation of symbols]

 1 ... Current detection device 2 ... Core 2a ... Gap part 2b ... End face 3 ... Case 3a ... Cylindrical part 3b ... Convex part 3c ... Screw hole 4 ... Magnetoelectric conversion element 5, 8 ... Mounting part 5a ... Case mounting hole 5b ... Concave part 5c ... Boss 8d ... Cover part 6 ... Printed circuit board 7 ... Screw

Claims (2)

[Scope of utility model registration request] 1. A current for detecting a change in magnetic flux generated in the core by arranging a magnetoelectric conversion element in the gap part of a core fixed in a case with a gap part provided on one side of a substantially square shape. In the detection device, an apron-shaped mounting portion is provided in the gap portion so as to straddle the gap portion by integrally molding a resin member, and the core is fixed to the case by the inner diameter of the core and the mounting portion. And the magnetoelectric conversion element is arranged in the gap portion by joint fastening when the attachment portion is attached to the case. 2. A rust preventive portion is formed by covering end faces of the gap portion of the core facing each other in a thin film with a resin member constituting the mounting portion when the mounting portion is integrally formed. The current detection device according to claim 1.