CN-122003610-A - Current sensor

Abstract

A current sensor (1) of the present invention, which suppresses a decrease in measurement accuracy due to positional displacement, has a magnetic detection unit (2), a housing (3), a cover (4), and a bus bar (5), wherein the bus bar (5) has a plate-shaped unit (52) formed with an opposing surface (51) opposing the magnetic detection unit (2), the plate-shaped unit (52) is held and sandwiched by the housing (3) and the cover (4), the housing (3) has a first reference surface (S1), the cover (4) has a second reference surface (S2), the bus bar (5) has a third reference surface (S3), and the housing (3), the cover (4), and the bus bar (5) are positioned by pressing the first reference surface (S1) and the second reference surface (S2) against the third reference surface (S3), the third reference surface (S3) being an end surface (53) in the plate-shaped unit (52) of the bus bar (5) in the plate thickness direction.

Inventors

• TIAN CUNXUE
• Ma Longlongbo
• An Buren
• WAKABAYASHI KAZUMI

Assignees

• 阿尔卑斯阿尔派株式会社

Dates

Publication Date

20260508

Application Date

20241008

Priority Date

20231117

Claims (20)

1. 1. A kind of current sensor, Comprises a magnetic detection part, a housing, a cover and a bus bar, The bus bar has a plate-like portion extending in an X direction, which is orthogonal to each other, and a Y direction, and a Z direction, and an opposing surface is formed to face the magnetic detection portion with the Z direction as a normal direction, The plate-like portion of the bus bar having the facing surface is held by sandwiching and holding the plate-like portion from both sides in the Z-direction by the housing and the cover, The current sensor is characterized in that, The housing has a first datum surface, the cover has a second datum surface, the bus bar has a third datum surface, By pressing the first reference surface and the second reference surface against the third reference surface, the housing, the cover and the bus bar are positioned, The third reference surface is an end surface of the plate-like portion of the bus bar in the Y direction.
2. 2. The current sensor according to claim 1, wherein, The bus bar has a narrowed neck portion having a cutout portion recessed in the Y direction, The third reference surface is the end surface of one of the narrowed portion in the Y direction.
3. 3. The current sensor according to claim 2, wherein, The housing has a bus bar groove portion on a surface facing the cover, the bus bar groove portion being capable of disposing the bus bar, The bus bar groove portion includes a guide portion protruding in a Y direction when viewed along a Z direction, The guide portion is inserted into the notch portion, and has the first reference surface at a portion facing the third reference surface.
4. 4. The current sensor according to claim 3, wherein, The cover has a pillar portion protruding in the Z direction from a face opposite to the housing, The guide portion and the pillar portion are inserted into and fitted to the cutout portion, The pillar portion has the second reference surface at a portion facing the third reference surface.
5. 5. The current sensor according to claim 4, wherein, Two of the guide portions paired in the X direction are provided separately with a gap interposed therebetween, The pillar portion is fitted in the gap, The two guide portions and the pillar portion paired in the X direction are fitted in the notch portion.
6. 6. The current sensor according to claim 5, wherein, The bus bar has the cutout portions on both sides of the plate-like portion in the Y direction, The housing has two guide portions corresponding to the two cutout portions in pairs in the X direction, The cover has two of the pillar portions corresponding to the two of the cutout portions, The end surface of the constricted portion in one of the cutout portions is the third reference surface, the guide portion fitted to the one of the cutout portions has the first reference surface, and the pillar portion fitted to a gap between two guide portions paired in the X direction fitted to the one of the cutout portions has the second reference surface.
7. 7. The current sensor according to claim 6, wherein, The end surface of the neck portion on the opposite side of the end surface of the neck portion from the one having the third reference surface is a pressing surface, The guide portions facing the pressing surface each have a first convex portion protruding in the Y direction on a surface facing the pressing surface, The support column part is provided with a second convex part protruding towards the Y direction on the surface opposite to the pressing surface, The first convex portion and the second convex portion are in pressure contact with the pressing surface.
8. 8. The current sensor according to claim 3, wherein, The notch portion has X facing surfaces facing each other in the X direction, Of the two guide portions paired in the X direction, A third protrusion protruding in the X direction is formed on a surface of one of the guide portions facing one of the X facing surfaces, A surface of the other guide portion facing the other facing surface contacts the other facing surface of the cutout portion, The third protruding portion is pressed against one of the opposing surfaces.
9. 9. The current sensor according to claim 4, wherein, The current sensor has a magnetic shield in the shape of a U, The magnetic shield member is insert-molded in the cover, both end portions protrude from a surface of the cover facing the bus bar, A pair of the pillar portions are disposed in contact with the magnetic shield member between the end portions of the magnetic shield member, The magnetic detection portion is disposed between the end portions of the magnetic shield member when the cover side is viewed from the case side along the Z axis.
10. 10. The current sensor according to claim 9, wherein, The housing has a shielding hole into which the end portion of the magnetic shield member can be inserted without contacting the guide portion.
11. 11. The current sensor according to claim 9, wherein, The Y-direction dimension of the magnetic shield member is smaller than the Y-direction dimension of the bus bar, The magnetic shield member is arranged so as not to protrude from the bus bar in the Y direction.
12. 12. The current sensor according to claim 2, wherein, The current sensor has a pair of holding members that hold the housing, the cover, and the bus bar together, The bus bar has a pair of insertion holes through which the holding member can be inserted, The pair of insertion holes are disposed on both sides with a narrowed neck portion in the X direction interposed therebetween.
13. 13. The current sensor according to claim 12, wherein, The holding member is a screw.
14. 14. The current sensor of claim 13, wherein, The magnetic detection part is mounted on a housing facing surface of the substrate facing the housing, The substrate is arranged on a substrate opposite surface of the shell opposite to a bus bar opposite surface opposite to the bus bar, The substrate is provided with the notch portion, The housing includes an engaging portion protruding from the substrate facing surface, The base plate is positioned with respect to the housing by engagement of the notch portion with the engagement portion.
15. 15. The current sensor of claim 14, wherein, The cover has a second insertion hole through which the screw is inserted, The housing has a boss for a screw hole protruding from the opposite surface of the base plate in the Z direction, The base plate is located between the two bosses for screw holes in the X direction when viewed along the Z direction, The base plate is disposed closer to the base plate facing surface of the housing than a straight line connecting the distal ends of the two screw hole bosses when viewed in the Y direction.
16. 16. The current sensor of claim 15, wherein, The housing has a wall portion protruding from the substrate facing surface in the Z direction so as to surround the periphery of the substrate, The wall portion protrudes to a position at least as far as the back surface of the case facing surface of the substrate from the substrate facing surface.
17. 17. The current sensor of claim 13, wherein, The cover has a protruding portion on a bottom surface of the bus bar opposite to the bus bar opposite surface, and a bottom portion as a region other than the protruding portion, A part of the magnetic shield member is insert-molded inside the protruding portion, A second insertion hole through which the screw can be inserted is provided in the bottom portion in the bottom surface, The height from the bottom to the front end of the protruding portion in the Z direction is larger than the height from the bottom to the head of the screw inserted through the second insertion hole.
18. 18. The current sensor of claim 17, wherein, The cover includes a partition wall portion protruding from the bottom portion in the Z direction and extending in the X direction.
19. 19. The current sensor of claim 18, wherein, The partition wall portions are disposed on both sides of the second insertion hole in the Y direction.
20. 20. The current sensor of claim 19, wherein, The height of the partition wall portion in the Z direction from the bottom portion is the same as the height of the protruding portion from the bottom portion of the bottom surface.

Description

Current sensor Technical Field The present invention relates to a current sensor for measuring a measured current flowing through a bus bar. Background In recent years, in order to control a power supply system of a vehicle or the like provided with various devices, a current sensor that measures a measured current flowing through the device is used. For example, there are coreless current sensors in which a bus bar is insert-molded in a case, and current sensors using a bus bar not insert-molded in a case for the purpose of meeting the demand for cost reduction in the market. In the current sensor, the bus bar of various shapes can be handled by a structure in which the housing and the bus bar are integrated by assembling without insert-molding the bus bar to the housing. Patent document 1 discloses an assembly structure of a current detecting device, and an object thereof is to provide an assembly structure of a current detecting device which is simple in structure, easy to assemble, and suitable for miniaturization of the current detecting device, wherein a protruding portion formed in a cover penetrates a hole formed in a bus bar, and is fitted into a hole formed in a lower surface of a housing. Patent document 2 discloses a current sensor, which aims to provide a high-precision current sensor, wherein a bracket is fixed to a current bar by screw fastening of a magnetic sensor element to the bracket. Patent document 3 discloses a current sensor in which positional displacement between a bus bar and a magnetic detection element is suppressed, and the housing has a first housing and a second housing that are provided so as to sandwich the bus bar and a circuit board, and the first housing and the second housing have sliding guide portions that are in contact with each other in the plate thickness direction of the bus bar and that are capable of sliding relative to each other in a direction inclined with respect to the plate thickness direction of the bus bar. In this current sensor, the protrusion of the first housing is fitted into the cutout of the bus bar, so that the bus bar is positioned with respect to the housing. Patent document 4 discloses a current sensor in which the shape of a bus bar is less restricted, and in which accuracy deterioration due to a positional displacement between a magnetic body and a bus bar relative to a magneto-sensitive element is reduced, so that a high-accuracy current measurement is possible, and in which a magneto-sensitive element mounting portion, a magnetic body mounting portion, and a bus bar are positioned and fixed from the thickness direction of the magnetic body mounting portion. In this current sensor, positioning of the bus bar in the width direction is performed based on the wall of the magnetic body mounting portion. Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication No. 2010-243440 Patent document 2 Japanese patent application laid-open No. 2015-31647 Patent document 3 Japanese patent application laid-open No. 2019-105613 Patent document 4 Japanese patent application laid-open No. 2021-152515 Disclosure of Invention Problems to be solved by the invention In the current detection devices and the current sensor described in patent documents 1 and 2, the assembly of the bus bar to the housing is performed with reference to a hole for screw tightening provided in the bus bar, and is not performed with reference to the sensing portion. Therefore, the accuracy of the current sensor may be deteriorated due to the variation in characteristics of the bus bar assembled to the housing. The current sensors described in patent documents 3 and 4 are each configured such that only one of the detachable housings is directly positioned with respect to the bus bar, and the other is positioned with respect to the one housing. Therefore, there is a possibility that the accuracy of the current sensor is deteriorated due to a positional shift when the other housing is positioned with respect to the one housing. Accordingly, an object of the present invention is to provide a current sensor with excellent measurement accuracy, in which a decrease in measurement accuracy due to positional displacement is suppressed. Means for solving the problems As means for solving the above problems, the present invention has the following configuration. A current sensor includes a magnetic detection portion, a case, a cover, and a bus bar having a plate-like portion extending in an X direction, a Y direction, and a Z direction orthogonal to each other, the plate-like portion having an opposing surface facing the magnetic detection portion and being formed in a normal direction to the Z direction, the plate-like portion having the opposing surface of the bus bar being held by the case and the cover from both sides in the Z direction, the current sensor is characterized in that the housing has a first reference surface, the cover has a second reference