Current sensor

Abstract

A current sensor 1 according to the present invention is used by being attached to a bus bar and comprises: a magnetic sensor 5 capable of detecting a magnetic field generated from a bus bar 2 when a current to be measured flows; and a body part 3 having an insertion hole 4 through which the bus bar 2 can be inserted and housing the magnetic sensor 5. The body part 3 comprises: a stopper part 32 for locking the bus bar 2 inserted into the insertion hole 4 to a predetermined position in a Y direction which is a longitudinal direction of the bus bar 2; and a crush rib 31 for strongly fitting with a first projection part 21 formed so as to protrude from a plate surface 2a of the bus bar 2 in a state where a second projection part 22 of the bus bar 2 is locked to the stopper part 32. As a result, a positional deviation between the bus bar and the magnetic detection element is suppressed.

Description

Technical Field

[0001] The present invention relates to a current sensor that measures a measured current flowing through various devices used for controlling a power supply system of a vehicle or the like.

Background Art

[0002] In recent years, in order to control a power supply system of a vehicle equipped with various devices, a current sensor that measures a measured current flowing through various devices has been used. As the current sensor, there are a bus bar integrated type and a bus bar separate type that is attached to the bus bar. The bus bar separate type current sensor is preferable from the viewpoints of standardization and cost reduction. However, it is difficult for the bus bar separate type current sensor to arrange the bus bar and the magnetic sensor (magnetic detection element) at a predetermined distance and maintain the positional relationship. For this reason, there is a problem that the measurement accuracy is likely to deteriorate due to the displacement between the bus bar and the magnetic sensor. Therefore, a bus bar separate type current sensor provided with a mechanism for preventing the displacement between the bus bar and the magnetic sensor has been proposed.

[0003] For example, Patent Document 1 describes a current sensor that is attached to a bus bar for the purpose of stabilizing the distance between the magnetic sensor and the bus bar in order to enable highly accurate current detection. The current sensor in this document includes a first pressing means for pressing a non-magnetic holder that holds a magnetic sensor against a partition wall inside an annular outer shell portion of a non-magnetic case, and a second pressing means for pressing a bus bar inserted into an insertion portion against the partition wall.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] The current sensor described in Patent Document 1 stabilizes the distance between the magnetic sensor and the busbar by using a pressing means that presses the holder of the magnetic sensor and the busbar against a partition wall. However, it is difficult to apply sufficient force with the pressing means of this current sensor, so there is a problem that misalignment between the magnetic detection element and the busbar is likely to occur when inserting the busbar into the insertion part or when fastening the busbar inserted into the insertion part to a predetermined position with screws. In addition, there is a problem that misalignment is likely to occur when the pressing force (biasing force) of the pressing means deteriorates due to heat or vibration of the busbar. Therefore, the present invention aims to provide a current sensor that is attached to a busbar and used in which the misalignment between the busbar and the magnetic detection element is suppressed. Furthermore, the objective is to provide a current sensor in which the misalignment between the magnetic detection element and the busbar is small, even when the means for attaching the current sensor to the busbar deteriorates due to the effects of heat generation or other factors of the current sensor. [Means for solving the problem]

[0006] As a means to solve the above-mentioned problems, the present invention has the following configuration. A current sensor comprising a magnetic sensor capable of detecting a magnetic field generated from a busbar when a current to be measured flows, and a main body portion for housing the magnetic sensor, wherein the main body portion comprises a through hole into which the busbar can be inserted, a stopper portion for locking the busbar inserted into the through hole at a predetermined position in the longitudinal direction of the busbar, and a crush rib for firmly engaging with a first projection formed protruding from one plate surface of the busbar when the busbar is locked to the stopper portion.

[0007] When the busbar is inserted into the through-hole, the first projection formed on the plate surface of the busbar is pressed in while crushing the crush rib provided on the main body, so that the crush rib and the first projection tightly fit together when the busbar is inserted into the through-hole. As a result, the busbar can be firmly fixed in a predetermined position on the main body when the busbar is locked to the stopper. Therefore, the misalignment between the busbar and the magnetic sensor can be reduced when inserting the busbar into the through-hole or when fastening the busbar with screws.

[0008] The stopper portion is formed to protrude from a first inner surface which is the surface on the inner surface of the insertion hole that faces one of the plate surfaces of the busbar, and the busbar may be locked by the stopper portion contacting a second protrusion which is formed to protrude from one of the plate surfaces of the busbar.

[0009] The busbar can be fixed in a predetermined position in the insertion hole by forcibly fitting the first protrusion and the crush rib together when the second protrusion abuts against the stopper and the second protrusion abuts against the stopper.

[0010] The stopper portion is an opening surface surrounding the opening of the insertion hole, and the busbar may be locked by contacting a second projection formed protruding from the end face in the width direction of the busbar. By using the opening surface surrounding the insertion hole as a stopper, the busbar can be locked in a predetermined position with a simple configuration.

[0011] The current sensor may be positioned on the other side of the busbar when the stopper portion locks the busbar in place. The second inner surface, which is the surface on the inner surface of the insertion hole facing the other plate surface of the busbar, comprises a horizontal portion formed in a planar shape parallel to the first inner surface on which the crush rib is formed, extending from one opening in the insertion hole toward the inside of the insertion hole, and a tapered portion formed so as to be closer to the first inner surface, extending from the other opening in the insertion hole toward the inside of the insertion hole, wherein the horizontal portion and the tapered portion are adjacent to each other via a boundary ridge, and the boundary ridge may be formed between a contact portion in which the stopper portion contacts the busbar and a tight-fitting portion in which the crush rib tightly fits with the busbar in the extending direction of the busbar.

[0012] By providing a horizontal section and a tapered section on the second inner surface of the insertion hole, and positioning the boundary ridge between them between the contact section and the tight-fitting section, the positional change between the magnetic sensor and the busbar can be reduced when the crush rib deteriorates over time due to the effects of heat generation from the busbar. In other words, the boundary ridge acts as a pivot point when the busbar moves, thus suppressing the displacement of the busbar. Furthermore, by providing a tapered section, the height of the other opening is increased, improving the workability when inserting the busbar into the insertion hole.

[0013] When viewed along the direction in which the busbar and the magnetic sensor are stacked, the boundary ridge and the magnetic sensor may overlap. By placing magnetic sensors near the boundary ridge, the positional misalignment between the busbar and the magnetic sensors can be reduced.

[0014] When viewed along the direction in which the busbar and the magnetic sensor are stacked, the stopper portion, the boundary ridge, and the magnetic sensor may overlap. By positioning the stopper portion at a location that overlaps with the boundary ridge and the magnetic sensor in the stacking direction, the movement of the busbar toward the stopper portion can be suppressed, thereby reducing the misalignment between the busbar and the magnetic sensor.

[0015] A current sensor comprising: a long plate-shaped busbar through which a current to be measured flows; a magnetic sensor capable of detecting a magnetic field generated from the busbar when the current to be measured flows; and a main body for housing the magnetic sensor, wherein the busbar comprises a first projection formed protruding from one plate surface and an engaging portion for locking the busbar inserted into a through hole in a predetermined position; the main body comprises a through hole into which the busbar can be inserted, a crush rib formed on a first inner surface which is the surface of the busbar facing the one plate surface inside the through hole and capable of tightly fitting with the first projection of the busbar, and a stopper portion capable of locking the engaging portion of the busbar, wherein the busbar is attached to the main body in such a state that when the busbar is inserted into the through hole, the first projection and the crush rib tightly fit together, the engaging portion and the stopper portion come into contact, and the magnetic sensor is positioned on the other plate surface side of the busbar.

[0016] When the busbar inserted into the through hole is locked to the stopper portion, the first projection formed on the plate surface of the busbar and the crush rib engage tightly, allowing the busbar to be attached to a predetermined position on the main body.

[0017] The busbar, when inserted into the through hole and with the engaging portion of the busbar locked to the stopper portion, has a fitting projection that protrudes in the width direction of the busbar in a portion located within the through hole and near the other opening, the through hole of the main body is formed such that its width increases from the one opening to the other opening, the width of the one opening is substantially the same as the width of the busbar in the portion without the fitting projection, and the width of the other opening may be substantially the same as the width of the busbar including the fitting projection. When the busbar's engaging portion is locked to the stopper portion of the main body, the busbar fits into both openings, thereby determining the busbar's position in the width direction and reducing misalignment between the busbar and the magnetic sensor.

[0018] The bus bar may have a narrow-width portion with a smaller width dimension than other portions between the first protruding portion and the engaging portion, and the magnetic sensor may be disposed at a position facing the narrow-width portion. By providing a narrow-width portion in the bus bar, the magnetic field generated around it becomes stronger when the measured current flows, improving the measurement accuracy of the current sensor. Also, when the current sensor detects an alternating current, deterioration of the frequency characteristics due to the skin effect can be suppressed.

Advantages of the Invention

[0019] In the current sensor of the present invention, by inserting the bus bar into the insertion hole, the first protruding portion of the bus bar and the crush rib of the main body portion are strongly fitted together, and the bus bar is attached to the main body portion in a state of contacting the stopper portion of the main body portion. Thus, since the bus bar and the main body portion are strongly fitted together when the bus bar is attached to a predetermined position of the main body portion, displacement between the bus bar and the magnetic sensor can be reduced. Also, by providing a horizontal portion and a tapered portion on the second inner surface in the insertion hole and disposing the boundary ridge line between the engaging portion and the crush rib in the extending direction of the bus bar, the boundary ridge line acts as a fulcrum of the bus bar. Therefore, displacement between the bus bar and the magnetic sensor when the crush rib deteriorates due to the influence of heat, vibration, etc. can be reduced.

Brief Description of the Drawings

[0020] [Figure 1A] It is a perspective view of the current sensor and the bus bar of the first embodiment. [Figure 1B] It is a perspective view of the current sensor in a state where the bus bar is attached. [Figure 2A] It is a cross-sectional view of the current sensor taken along line AA of FIG. 1B. [Figure 2B] It is a plan view of the current sensor of FIG. 2A. [Figure 3A] It is a cross-sectional view of the current sensor according to a modification. [Figure 3B] It is a plan view of the current sensor of FIG. 3A. [Figure 4A]This is a schematic diagram showing the positional relationship between the busbar and the main body during insertion. [Figure 4B] Figure 4A is a cross-sectional view of the current sensor along line AA. [Figure 5A] This is a schematic diagram showing the positional relationship between the busbar and the main body when the first projection of the busbar is in contact with the crush rib. [Figure 5B] Figure 5A is a cross-sectional view of the current sensor along line AA. [Figure 6A] This is a schematic diagram showing the positional relationship between the busbar and the main body when the busbar is inserted to its predetermined position. [Figure 6B] Figure 6A is a cross-sectional view of the current sensor along line AA. [Figure 7A] This is a schematic diagram showing the positional relationship between the busbar and the main body when the current sensor is inserted according to a modified example. [Figure 7B] This is a cross-sectional view of the current sensor along line AA in Figure 7A. [Figure 7C] Figure 7A is a front view of the current sensor. [Figure 8] This is a plan view of a current sensor that schematically shows a configuration for preventing busbar displacement in the X direction. [Figure 9] This is a cross-sectional view of the current sensor according to the second embodiment. [Figure 10] This is a cross-sectional view of a modified current sensor. [Figure 11] This is a schematic cross-sectional view illustrating the case where a busbar is fastened to a stepped section. [Figure 12] This is a cross-sectional view illustrating the simulation of the current sensor in the embodiment. [Figure 13] This is a cross-sectional view illustrating the simulation of a current sensor in a comparative example. [Figure 14A] Graph showing the results of the example (Z1 direction, no damage to the crush ribs) [Figure 14B] Graph showing the results of the example (Z1 direction, with crush rib damage) [Figure 15A] Graph showing the results of the comparative example (Z1 direction, no damage to the crush rib) [Figure 15B]Graph showing the results of the comparative example (Z1 direction, with crush rib damage) [Figure 16A] Graph showing the results of the example (Z2 direction, no damage to the crush ribs) [Figure 16B] Graph showing the results of the example (Z2 direction, with crush rib damage) [Figure 17A] Graph showing the results of the comparative example (Z2 direction, no damage to the crush ribs) [Figure 17B] Graph showing the results of the comparative example (Z2 direction, with crush rib damage) [Best Mode for Carrying Out the Invention]

[0021] Embodiments of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same component is given the same number, and its description is omitted. Reference coordinates are shown in each drawing as appropriate to indicate the positional relationship of each component. In the reference coordinates, the width direction of the busbar is the X direction, the extension direction of the busbar is the Y direction, and the direction perpendicular to the X and Y directions is the Z direction. The X direction is the direction of the sensitivity axis of the magnetic sensor, and the Y and Z directions are perpendicular to the sensitivity axis.

[0022] [First Embodiment] Figure 1A is a perspective view of the current sensor 1 and busbar 2 of this embodiment, and Figure 1B is a perspective view of the current sensor 1 with the busbar 2 attached. As shown in these figures, the current sensor 1 is a busbar-separated type current sensor in which the busbar 2 is inserted into the insertion hole 4 of the main body 3, and the busbar 2 is not insert molded into the main body 3.

[0023] Figure 2A is a schematic cross-sectional view showing the configuration of the current sensor 1 along line AA in Figure 1B, and Figure 2B is a schematic plan view showing the configuration of the current sensor 1. The busbar 2 is a long plate shape, with its plate surface 2b facing the magnetic sensor 5, and having a first projection 21 and a second projection (engaging portion) 22 at different positions in the Y direction, which is the extension direction. Both the first projection 21 and the second projection 22 are formed to protrude from the plate surface 2a. The first projection 21 and the second projection 22 are for attaching and holding the busbar 2, which is inserted into the insertion hole 4 of the main body 3, in a predetermined position.

[0024] When the busbar 2 is installed in a predetermined position in the insertion hole 4, the first projection 21 and the second projection 22 are positioned inside the insertion hole 4, and both ends of the busbar 2 protrude from the opening 41 on the Y1 side and the opening 42 on the Y2 side of the insertion hole 4, respectively.

[0025] The main body 3 has an insertion hole 4 into which the busbar 2 can be inserted, a crush rib 31, and a stopper portion 32. The crush rib 31 is one of the surfaces inside the insertion hole 4 and is formed on the first inner surface 4a facing one of the plate surfaces 2a of the busbar 2, and when the busbar 2 is locked to the stopper portion 32, it fits tightly with the first projection 21 of the busbar 2. The stopper portion 32 is formed to protrude from the first inner surface 4a within the insertion hole 4. When the busbar 2 is inserted into the insertion hole 4, the second protrusion 22, which is formed to protrude from one of the plate surfaces 2a, abuts against and contacts the stopper portion 32, thereby locking the busbar 2 in a predetermined position in the Y direction, which is the extension direction of the busbar 2. In the state where the stopper portion 32 locks the busbar 2, the magnetic sensor 5 is located on the other plate surface 2b side of the busbar 2.

[0026] When inserting the busbar 2 into the insertion hole 4 of the main body 3, the first protrusion 21 of the busbar 2 moves while crushing a part of the crush rib 31 of the main body 3, causing the first protrusion 21 and the crush rib 31 to tightly engage. Then, at a predetermined position in the Y direction, the insertion of the busbar 2 into the insertion hole 4 is completed when the second protrusion 22 of the busbar 2 and the stopper portion 32 of the main body 3 come into contact, and the busbar 2 is attached to the main body 3.

[0027] The crush rib 31 is located near the opening 42 on the Y2 side. Therefore, even if a part of the crush rib 31 is crushed and debris is generated, there is little possibility that the debris will travel to the busbar 2 near the opening 41 on the Y1 side. In addition, the first projection 21, which tightly engages with the crush rib 31, stops at a position before the opening 42 on the Y2 side within the insertion hole 4, so it is unlikely that the crush rib 31 will be scraped off. Thus, the risk of debris affecting welding or other processes for fastening the busbar 2 near the openings 41 on the Y1 side and 42 on the Y2 side to other members can be reduced.

[0028] The busbar 2 in Figures 2A and 2B has two protrusions, but it may also have a configuration with three or more protrusions. Alternatively, instead of the second protrusion 22, a recess may be formed on the plate surface 2a, and the busbar 2 may be locked in a predetermined position in the Y direction by fitting with a convex portion formed on the first inner surface 4a of the insertion hole 4 of the main body 3. This configuration can reduce the amount of metal used in the busbar 2.

[0029] Inside the main body 3, a magnetic sensor 5 and a magnetic shield 6 are provided, positioned opposite the busbar 2. The magnetic sensor 5 has a magnetoresistive element and detects the magnetic field generated from the busbar 2 when the current to be measured flows. Examples of magnetoresistive elements include giant magnetoresistive elements (GMR elements), anisotropic magnetoresistive elements (AMR elements), tunnel magnetoresistive elements (TMR elements), and Hall elements. The magnetic sensor 5 is mounted on a substrate 7, and the substrate 7 is attached to the main body 3.

[0030] The busbar 2 is held in a state where the first protrusion 21 and the crush rib 31 are tightly fitted together, and the second protrusion 22 and the stopper portion 32 are in contact. In this state, the magnetic sensor 5 is positioned opposite the portion of the busbar 2 between the first protrusion 21 and the second protrusion 22.

[0031] The magnetic shield 6 can be made, for example, by stacking multiple metal plates of the same shape. By providing the magnetic shield 6, magnetic noise from the outside to the magnetic sensor 5 is reduced, thereby improving the measurement accuracy of the magnetic sensor 5. In the current sensor 1, flat magnetic shields 6 are provided on both sides of the magnetic sensor 5 in the Z direction. The magnetic shield 6 on the Z1 side is insert-molded into the main body 3, and the magnetic shield 6 on the Z2 side is provided on the side of the substrate 7 opposite to the side on which the magnetic sensor 5 is located. Instead of flat magnetic shields 6, U-shaped or C-shaped (core-shaped) magnetic shields can also be used.

[0032] By matching the width of the insertion hole 4 with the width of the busbar 2, the position of the busbar 2 in the X direction on the main body 3 can be determined. By bringing the second projection 22 of the busbar 2 into contact with the stopper portion 32 of the main body 3, the busbar 2 can be locked in place when it is inserted to a predetermined position, thereby determining the position of the busbar 2 in the Y direction on the main body 3. Then, with the busbar 2 inserted to a predetermined position, the position of the busbar 2 in the Z direction on the main body 3 can be determined by forcefully fitting the first projection 21 of the busbar 2 with the crush rib 31 of the main body 3.

[0033] Although it was stated that the width of the insertion hole 4 and the width of the busbar 2 should match, in reality, the dimensions are controlled so that the width of the insertion hole 4 is slightly larger, to the extent that there is no significant play between the insertion hole 4 and the busbar 2. If the width of the insertion hole 4 and the width of the busbar 2 were exactly the same, the frictional resistance when inserting the busbar 2 into the insertion hole 4 would be extremely high. This is because high frictional resistance during insertion could cause the busbar 2 to deform or generate shavings by scraping the inner surface of the insertion hole 4.

[0034] As described above, the busbar 2 can be inserted into the insertion hole 4 of the main body 3 and attached to a predetermined position on the main body 3. When the busbar 2 is attached to the main body 3, the first protrusion 21 of the busbar 2 and the crush rib 31 of the main body 3 are tightly fitted together. Therefore, it is possible to prevent the position of the busbar 2 on the main body 3 from shifting during installation or when fastening to other members after installation.

[0035] <Variation> Figure 3A is a schematic cross-sectional view showing the configuration of the current sensor 1 according to a modified example, and Figure 3B is a plan view of the current sensor 1 in Figure 3A. The modified current sensor 1 has second protrusions 23 that protrude from the side surfaces 2c and 2d in the width direction (X direction) of the busbar 2, respectively, instead of the second protrusion 22 that protrudes from the plate surface 2a. When the busbar 2 is inserted into the insertion hole 4, the second protrusions 23 abut against the opening surface 33 of the main body 3, thereby locking the busbar 2 in a predetermined position on the main body 3. With the busbar 2 locked in a predetermined position on the main body 3 by the second protrusions 23 and the opening surface 33, the first protrusion 21 of the busbar 2 and the crush rib 31 of the main body 3 are tightly fitted together. The opening surface 33 is the outer surface of the main body 3 that surrounds the opening 41 of the insertion hole 4.

[0036] Thus, in this modified current sensor 1, the opening surface 33 of the main body 3 contacts the second protrusion 23 of the busbar 2 to lock the busbar 2, eliminating the need to provide a stopper portion 32 on the main body 3. Therefore, the main body 3 can be made with a simpler configuration.

[0037] Figure 4A is a schematic diagram illustrating the positional relationship between the busbar 2 and the main body 3 during insertion. In this figure, all parts except the magnetic sensor 5 are shown with solid lines to show the positional relationship of each part when viewed in the Z direction. Figure 4B is a schematic cross-sectional view illustrating the configuration of the current sensor 1 along line AA in Figure 4A. Similarly, in Figures 5A, 6A, and 7A, each part is shown with solid lines for convenience in illustrating the positional relationship.

[0038] As shown in FIG. 4A, the first protrusion 21 and the second protrusion 22 on the bus bar 2 are configured as rectangular protrusions in a plan view. Further, the crash ribs 31 and the stopper portions 32 on the main body portion 3 are formed by two rectangular protrusions having the Y direction as the longitudinal direction.

[0039] Note that the crash rib 31 is in contact with the first protrusion 21 and is set to have a strength such that it will deliberately deform (be crushed) when further pushed in the Y2 direction. Also, the stopper portion 32 is in contact with the second protrusion 22 and is set to have a strength such that it will not deform (be crushed) when further pushed in the Y2 direction. The crash rib 31 is provided between the two protrusions of the stopper portion 32, and in the X direction, the width d1 of the first protrusion 21 of the bus bar 2, the width d2 of the second protrusion 22, the width D1 inside the two protrusions of the crash rib 31, and the width D2 inside the two protrusions of the stopper portion 32 satisfy the relationship D1 < d1 < D2 < d2.

[0040] Also, as shown in FIG. 4B, in the Z direction, the height h1 from the plate surface 2b of the first protrusion 21 of the current sensor 1, the height h2 from the plate surface 2b of the second protrusion 22, the height H0 of the insertion hole 4, the height H1 of the gap between the second inner surface 4b of the insertion hole 4 facing the other plate surface 2a of the bus bar 2 and the crash rib 31, and the height H2 of the gap between the second inner surface 4b and the stopper portion 32 satisfy the relationship H1 < H2 < h1 < h2 < H0.

[0041] The width d1 of the first protrusion 21 of the bus bar 2 is smaller than the width D2 between the two rectangular protrusions of the stopper portion 32. For this reason, the first protrusion 21 with the height h1 of the bus bar 2 passes through the insertion hole 4 with the height H0 between the two rectangular protrusions of the stopper portion 32 without interfering with the stopper portion 32 until it contacts the crash rib 31 inside the insertion hole 4.

[0042] FIG. 5A is a schematic diagram showing the positional relationship between the bus bar 2 and the main body portion 3 when the first protrusion 21 of the bus bar 2 contacts the crash rib 31. FIG. 5B is a cross-sectional view schematically showing the configuration of the current sensor 1 taken along line AA in FIG. 5A. Figure 6A is a schematic diagram showing the positional relationship between the busbar 2 and the main body 3 when the busbar 2 is inserted to a predetermined position. Figure 6B is a schematic cross-sectional view showing the configuration of the current sensor 1 along line AA in Figure 6A.

[0043] The height h1 of the first protrusion 21 is greater than the height H1 of the gap in the through hole 4 where the crush rib 31 is provided. Therefore, from the position shown in Figure 5A to the position shown in Figure 6A, the first protrusion 21 moves while crushing a part of the crush rib 31, maintaining contact between the first protrusion 21 and the crush rib 31 in the Z direction. With this configuration, the busbar 2 is press-fitted into the through hole 4, and the first protrusion 21 of the busbar 2 and the crush rib 31 of the main body 3 are tightly fitted together.

[0044] Therefore, when the second projection 22 abuts against the stopper portion 32, the strong engagement between the first projection 21 and the crush rib 31 can fix the position of the busbar 2 in the Z direction on the main body 3. Furthermore, the engagement between the second projection 22 and the stopper portion 32 determines the position of the busbar 2 in the Y direction on the main body 3. In addition, the X-direction position of the busbar 2 on the main body 3 is determined by matching the width of the busbar 2 with the width of the insertion hole 4 in the X direction.

[0045] As shown in Figures 6A and 6B, the busbar 2 has a narrow section 25 between the first protrusion 21 and the second protrusion 22, which has a narrower width in the X direction than the rest of the busbar. When the busbar 2 is mounted in a predetermined position on the main body 3, the magnetic sensor 5 is positioned opposite the narrow section 25. Near the narrow section 25, a stronger magnetic field is generated than in other parts when the current to be measured flows through the busbar 2. Therefore, the magnetic sensor 5 can efficiently detect the magnetic field generated when the current to be measured flows through the busbar 2. Furthermore, when the magnetic sensor 5 detects the alternating current flowing through the busbar 2, it can suppress the degradation of frequency characteristics due to the skin effect.

[0046] <Variation> Figure 7A is a schematic diagram showing the positional relationship between the busbar 2 and the main body 3 when inserted, and Figure 7B is a schematic cross-sectional view showing the configuration of the current sensor 1 of line AA in Figure 7A. Figure 7C is a front view of the current sensor 1 of Figure 7A when viewed from the Y2 side towards the Y1 direction. As shown in Figure 7A, the configuration of the first protrusion 21 and the second protrusion 22 in the busbar 2 is the same as in the configuration shown in Figure 4A. It differs from the configuration shown in Figure 4A in that the stopper portion 32 in the main body portion 3 is made up of a single rectangular protrusion, and the crush rib 31 is provided protruding from the stopper portion 32 rather than from the first inner surface 4a in the insertion hole 4.

[0047] As shown in Figure 7B, in the modified current sensor 1, the height h1 of the first protrusion 21, the height h2 of the second protrusion 22, the height H0 of the insertion hole 4, the height H1 of the gap between the second inner surface 4b of the insertion hole 4 facing the other plate surface 2a of the busbar 2 and the crush rib 31, and the height H2 of the gap between the second inner surface 4b and the stopper portion 32 are all in the Z direction.

[0048] In the modified example, the height h1 of the first projection 21 is smaller than the height H2 of the gap. Therefore, the first projection 21 of the busbar 2, with height h1, passes through the gap of height H2 without interfering with the stopper portion 32 until it contacts the crush rib 31 inside the insertion hole 4.

[0049] As shown in Figure 7C, when viewed from Y2 in the direction of Y1, a part of the first projection 21 of the busbar 2 and a part of the crush rib 31 of the main body 3 overlap. Therefore, when the second projection 22 of the busbar 2 and the stopper portion 32 of the main body 3 are in contact, the first projection 21 of the busbar 2 and the crush rib 31 of the main body 3 are tightly fitted together.

[0050] Figure 8 is a schematic plan view showing a configuration that the current sensor 1 of this embodiment may have to prevent displacement of the busbar 2 in the X direction. ​As shown in the figure, the insertion hole 4 may be configured such that, when viewed along the Z direction, which is the stacking direction of the busbar 2 and the magnetic sensor 5, the width dimension D41 of the opening 41 is larger than the width dimension D42 of the opening 42, and the width dimension increases from the opening 42 towards the opening 41.

[0051] Furthermore, when the second projection 22 of the busbar 2 is locked to the stopper portion 32 (see Figures 6A and 6B), the busbar 2 may have fitting protrusions 24 on both sides of the busbar 2 in the width direction (X direction) that protrude in the width direction (X direction) of the busbar 2 in a state where the second projection 22 of the busbar 2 is locked to the stopper portion 32, and are located within the insertion hole 4 and near the opening 41.

[0052] The width dimension D42 of the opening 42 is approximately the same as the width dimension D0 of the busbar 2 in the portion without the fitting projection 24, and the width dimension D41 of the opening 41 is approximately the same as the width dimension D24 of the busbar 2 including the fitting projection 24.

[0053] With the configuration shown in Figure 8 described above, when the second projection 22 of the busbar 2 is locked to the stopper portion 32, the busbar 2 fits into the openings 41 and 42 on both sides of the insertion hole 4, allowing for positioning in the X direction on the main body portion 3.

[0054] [Second Embodiment] Figure 9 is a cross-sectional view of the current sensor 8 of this embodiment. The current sensor 8 differs from the current sensor 1 of the first embodiment in that the second inner surface 4b of the insertion hole 4 facing the plate surface 2b of the busbar 2 has a horizontal portion 43 and a tapered portion 44.

[0055] The horizontal portion 43 is a part formed in a planar shape parallel to the first inner surface 4a, extending from the opening 42 in the through hole 4 toward the inside of the through hole 4 (from Y2 to Y1 direction). The horizontal portion 43 is formed so as to be parallel to the plate surface 2b of the busbar 2 when the busbar 2 is attached to a predetermined position in the main body portion 3.

[0056] The tapered portion 44 is formed such that the distance from the opening 41 in the through hole 4 toward the inside of the through hole 4 (from Y1 to Y2 direction) decreases, and is inclined with respect to the plate surface 2b of the busbar 2 when the busbar 2 is installed. The tapered portion 44 is formed such that the distance from the plate surface 2b of the busbar 2 inside the through hole 4 decreases as it goes further into the through hole 4. In other words, when the busbar 2 is installed in a predetermined position on the main body 3, the tapered portion 44 is formed such that the distance from the plate surface 2b of the busbar 2 decreases toward the inside of the through hole 4.

[0057] The horizontal section 43 and the tapered section 44 are adjacent to each other via a boundary ridge 45. In other words, the horizontal section 43 and the tapered section 44 are continuously provided with the boundary ridge 45 as the boundary. When the bus bar 2 is attached to a predetermined position on the main body 3, the boundary ridge 45 is located between the first projection 21 and the second projection 22 of the bus bar 2 in the Y direction, which is the extension direction of the bus bar 2. That is, the boundary ridge 45 is formed to be located between the contact portion 320 of the stopper portion 32 with the second projection 22 of the bus bar 2 and the tightly fitting portion 310 of the crush rib 31 with the first projection 21 of the bus bar 2.

[0058] If the crush rib 31 softens over time due to high temperature or vibration, and its function of positioning the busbar 2 in the Z direction deteriorates, the Y1 end of the busbar 2 may tilt toward the Z1 side due to the influence of the mounting position of the current sensor 8. The boundary ridge 45 functions as a pivot point when the busbar 2 tilts as described above. That is, when the busbar 2 tilts, the plate surface 2b of the busbar 2 separates from the horizontal section 43, but the separation distance is 0 at the boundary ridge 45, and the separation distance becomes smaller the closer it is to the boundary ridge 45. Since the part of the busbar 2 facing the magnetic sensor 5 is located near the boundary ridge 45, the change in the distance between the magnetic sensor 5 and the busbar 2 when the busbar 2 tilts can be reduced.

[0059] Furthermore, by positioning the magnetic sensor 5 so that it overlaps with the stopper portion 32 when viewed along the Z direction, the stopper portion 32 can restrict the movement of the Y1 side end of the busbar 2 in the Z2 direction. This reduces the amount of displacement in the distance between the magnetic sensor 5 and the busbar 2, thereby reducing the change in the distance between the magnetic sensor 5 and the busbar 2 when the busbar 2 is tilted. Therefore, it is possible to suppress the decrease in the measurement accuracy of the current sensor 8 due to changes in the distance between the magnetic sensor 5 and the busbar 2.

[0060] <Variation> Figure 10 is a cross-sectional view of a modified example of the current sensor 8. In the modified example shown in the figure, the magnetic sensor 5 is positioned so that it coincides with the boundary ridge 45 and the stopper portion 32 when viewed along the Z direction in which the busbar 2 and the magnetic sensor 5 are stacked, which differs from the current sensor 8 in Figure 9. With this configuration, the magnetic sensor 5 is located near the boundary ridge 45, which functions as a pivot point when the Y1 end of the busbar 2 tilts towards the Z1 side, thus further reducing the displacement of the distance between the magnetic sensor 5 and the busbar 2.

[0061] Figure 11 is a schematic cross-sectional view showing a modified example in which the busbar 2 of the current sensor 8 is fastened to a stepped portion. As shown in the figure, when the Y1 side end of the busbar 2 is attached to the fastening point 82 by the fastening means 81, a force in the Z1 direction is applied to the Y1 side end of the busbar 2, which may cause the busbar 2 to tilt as shown by the dashed line. In such a case, the tapered portion 44 allows the busbar 2 to tilt with the boundary ridge 45 as the pivot point. That is, even if the busbar 2 tilts in the vicinity of the boundary ridge 45, the relative position between the busbar 2 and the boundary ridge 45 does not change much, so the amount of displacement of the busbar 2 in the vicinity of the boundary ridge 45 can be reduced. Therefore, when the current sensor 8 is to be attached as shown in Figure 11, the effect of the misalignment between the busbar 2 and the magnetic sensor 5 can be more effectively reduced by placing the magnetic sensor 5 in the vicinity of the boundary ridge 45.

[0062] The smaller the misalignment between the busbar 2 and the magnetic sensor 5, the smaller the measurement error of the current sensor 8 can be. Note that the busbar 2 shown by the dashed line in Figure 11 is attached to the fastening point 82 by the fastening means 81 at the Y1 side end of the busbar 2, and the tight fit between the first protrusion 21 and the crush rib 31 is loosened. When the first protrusion 21 and the crush rib 31 maintain a tight fit, the Y2 side end of the busbar 2 maintains the same state as the busbar 2 shown by the solid line in Figure 11. [Examples]

[0063] Figure 12 is a cross-sectional view of the current sensor 8 illustrating the simulation method of this embodiment. As shown in the figure, for a modified example of the current sensor 8 in the second embodiment, the displacement occurring in the busbar 2 and the substrate 7 on which the magnetic sensor 5 is placed was simulated when the Y1 side end of the busbar 2 was displaced in the Z1 direction or the Z2 direction. The displacement was evaluated by simulation for the case where there was no damage to the crush rib 31 and the case where there was damage to the crush rib 31.

[0064] Figure 13 is a cross-sectional view of a comparative example current sensor 80. As shown in the figure, a simulation was performed on the current sensor 80, which has crush ribs 31 on both sides in the Y direction with the magnetic sensor 5 in between, under the same conditions as the current sensor 8 in Figure 12.

[0065] Figures 14A and 14B show the simulation results of embodiments in which the busbar 2 is displaced in the Z1 direction, with and without damage to the crush rib 31. Figures 15A and 15B show the simulation results of comparative examples in which the busbar 2 is displaced in the Z1 direction, with and without damage to the crush rib 31. In each graph, the Y-axis position 0 represents the position where the magnetic sensor 5 is located on the substrate 7, and the difference in output values ​​indicated by the arrows shows the relative positional displacement between the busbar 2 and the magnetic sensor 5 (the same applies to Figures 16A to 17B).

[0066] When the Y1 end of the busbar 2 was moved in the Z1 direction, regardless of whether the crush rib 31 was damaged or not, the current sensor 8 of the embodiment showed a significantly reduced misalignment between the busbar 2 and the magnetic sensor 5 provided on the substrate 7 compared to the current sensor 80 of the comparative example. This result is thought to be because, by providing the tapered portion 44, the pivot point when the busbar 2 is displaced moved from the opening 41 shown by the black circle in Figure 13 to the boundary ridge line 45 shown by the black circle in Figure 12, and the misalignment of the busbar 2 near the boundary ridge line 45 was reduced.

[0067] Figures 16A and 16B show the results of an embodiment in which the busbar 2 is displaced in the Z2 direction, with and without damage to the crush rib 31. Figures 17A and 17B show comparative examples of displacing the busbar 2 in the Z2 direction, with and without damage to the crush rib 31.

[0068] When the Y1 end of the busbar 2 was moved in the Z2 direction, if there was no damage to the crush rib 31, the amount of displacement in the current sensor 8 of the embodiment was about the same as that of the current sensor 80 of the comparative example. If there was damage to the crush rib 31, the amount of displacement in the current sensor 8 of the embodiment was slightly reduced compared to the current sensor 80 of the comparative example. As shown by the black circles in Figures 12 and 13, in both the current sensor 8 of the embodiment and the current sensor 80 of the comparative example, the fulcrum when the busbar 2 is displaced is the opening 42. Therefore, the result when there is damage to the crush rib 31 is thought to be due to the fact that the displacement of the busbar 2 was suppressed by the stopper portion 32 in the current sensor 8 of the embodiment.

[0069] To summarize the simulation results mentioned above, the following can be said: In the current sensor 8 of the embodiment, when the Y1 side end of the busbar 2 is moved in the Z1 direction, the busbar 2 tilts with the boundary ridge 45 as the pivot point. Therefore, the closer the magnetic sensor 5 is positioned to the position opposite the boundary ridge 45, the smaller the positional displacement between the magnetic sensor 5 and the busbar 2 can be kept. When the Y1 side end of the busbar 2 is moved in the Z2 direction, the busbar 2 tilts with the Z1 side end of the opening 42 as the pivot point. Therefore, the closer the magnetic sensor 5 is positioned to the position opposite the Z1 side end of the opening 42, the smaller the positional displacement between the magnetic sensor 5 and the busbar 2 can be kept. Consequently, if the magnetic sensor 5 is positioned to face the region between the boundary ridge 45 and the opening 42, it is unlikely that the positional displacement between the busbar 2 and the magnetic sensor 5 will become extremely large, regardless of whether the Y1 side end of the busbar 2 is moved in the Z1 or Z2 direction. Therefore, by positioning the magnetic sensor 5 opposite the region between the boundary ridge 45 and the opening 42, measurement errors of the current sensor 8 can be suppressed even if the position of the busbar 2 fluctuates in the Z direction.

[0070] The embodiments disclosed herein are illustrative in all respects and are not limited thereto. The scope of the invention is indicated by the claims rather than solely by the above-described embodiments, and all modifications within the meaning and scope equivalent to the claims are intended. [Industrial applicability]

[0071] The present invention is useful as a current sensor for measuring the current flowing through various devices used, for example, in the control of a vehicle's power supply system. [Explanation of symbols]

[0072] 1: Current sensor 2: Busba 2a: Board surface 2b: Board surface 2c: Side 2d: side 21: 1st protrusion 22:Second protrusion 23:Second protrusion 24: Fitting protrusion 25: Narrow part 3: Main body 31: Crushed Ribs 310: Strong interlocking part 32: Stopper section 320: Contact area 33: Opening surface 4: Through hole 4a: First inner surface 4b: Second inner surface 41 :Aperture 42 :Aperture 43:Horizontal part 44: Tapered section 45: Boundary ridge 5: Magnetic sensor 6: Magnetic shielding 7: Circuit board 8: Current sensor 80: Current sensor 81: Fastening means 82: Place of fastening H0: Height H1: Height H2: Height h1: height h2: height D1:Width D2:Width d1:Width d2: Width D0: Width dimension D24: Width dimension D41: Width dimension D42: Width dimension

Claims

1. A current sensor comprising a magnetic sensor capable of detecting a magnetic field generated from a busbar when a current to be measured flows, and a main body that houses the magnetic sensor, The main body portion is The busbar has an insertion hole into which it can be inserted, A stopper portion for locking the busbar inserted into the through hole at a predetermined position in the longitudinal direction of the busbar, The busbar is locked to the stopper portion and includes a crush rib for tightly engaging with a first projection formed protruding from one of the plate surfaces of the busbar, The current sensor is characterized in that the crush rib is provided on the surface inside the insertion hole, and when the busbar is inserted into the insertion hole of the main body, the first protrusion moves while crushing a part of the crush rib, thereby engaging with the first protrusion.

2. The stopper portion is formed to protrude from the first inner surface, which is the surface of the busbar facing the one plate surface on the inner surface of the insertion hole. The current sensor according to claim 1, wherein the stopper portion locks the busbar by contacting a second protrusion formed protruding from one of the plate surfaces of the busbar.

3. The current sensor according to claim 1, wherein the stopper portion is an opening surface surrounding the opening of the insertion hole, and locks the busbar by contacting a second projection formed protruding from the end face in the width direction of the busbar.

4. With the stopper portion locked in place for the bus bar, The current sensor according to claim 1, wherein the magnetic sensor is located on the other plate surface side of the busbar.

5. The second inner surface, which is the surface on the inner surface of the insertion hole that faces the other plate surface of the busbar, From one opening in the insertion hole toward the inside of the insertion hole, a horizontal portion is formed in a planar shape parallel to the first inner surface on which the crush rib is formed, The insertion hole comprises a tapered portion formed such that the distance from the other opening toward the inside of the insertion hole decreases, The horizontal portion and the tapered portion are adjacent to each other via a boundary ridge. The current sensor according to claim 4, wherein the boundary ridge is formed between a contact portion where the stopper portion contacts the busbar and a tight-fitting portion where the crush rib tightly fits with the busbar in the extending direction of the busbar.

6. The current sensor according to claim 5, wherein when viewed along the direction in which the busbar and the magnetic sensor are stacked, the boundary ridge and the magnetic sensor overlap.

7. The current sensor according to claim 5, wherein when viewed along the direction in which the busbar and the magnetic sensor are stacked, the stopper portion, the boundary ridge, and the magnetic sensor overlap.

8. A current sensor comprising a long, plate-shaped busbar through which the current to be measured flows, a magnetic sensor capable of detecting the magnetic field generated from the busbar when the current to be measured flows, and a main body that houses the magnetic sensor, The aforementioned bus bar is A first protrusion formed protruding from one of the plate surfaces, It comprises an engaging portion for locking the busbar inserted into the insertion hole in a predetermined position, The main body is, The insertion hole into which the busbar can be inserted, A crush rib formed on the first inner surface, which is the surface of the busbar facing one of the plate surfaces inside the insertion hole, is capable of being firmly fitted with the first protrusion of the busbar. The bus bar comprises a stopper portion capable of locking the engagement portion, By inserting the busbar into the aforementioned insertion hole, The busbar is attached to the main body with the first protrusion and the crush rib tightly fitted together, the engaging portion and the stopper portion in contact, and the magnetic sensor positioned on the other plate surface side of the busbar. The current sensor is characterized in that the crush rib is provided on the surface inside the insertion hole, and when the busbar is inserted into the insertion hole of the main body, the first protrusion moves while crushing a part of the crush rib, thereby engaging with the first protrusion.

9. The busbar, when inserted into the insertion hole and with the engaging portion of the busbar locked to the stopper portion, has a fitting projection that protrudes in the width direction of the busbar in a portion located within the insertion hole and near the other opening, The current sensor according to claim 8, wherein the insertion hole of the main body is formed such that its width dimension increases from one opening to the other opening, the width dimension of the one opening is substantially the same as the width dimension of the busbar in the portion without the fitting projection, and the width dimension of the other opening is substantially the same as the width dimension of the busbar including the fitting projection.

10. The bus bar has a narrower portion between the first projection and the engaging portion, which is narrower in width than the other portions. The current sensor according to claim 8, wherein the magnetic sensor is positioned opposite the narrow portion.

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