JP2013205194A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lag of a physical relationship between a magnetic sensor 30 and a magnetic core 20 in use.SOLUTION: A current sensor S includes: a magnetic core 20 that surrounds a bus bar 10 in which a current flows; a magnetic sensor 30 on a circuit board 40 that detects changes in a magnetic field generated in the notch part 21 of the core 20; a case 50 in which the bus bar, the magnetic core, the magnetic sensor, and the circuit board are installed; and the cover 60 of the case. The magnetic sensor 30 rises from the circuit board with legs 32. The core 20 is firmly inserted to be supported and fixed in the cylindrical part 54 of the case with ribs 55. The magnetic sensor is inserted to be supported and fixed in a slit 56 and located in the notch part 21 of the magnetic core. Through both inserted to be supported and fixed structure, lag of physical relationship between the magnetic sensor 30 and the magnetic core 20 in use can be prevented.

Description

  The present invention relates to an electric motor (EV), a fuel cell vehicle (FCV), a hybrid vehicle (HV), a plug-in hybrid vehicle (PHV, PHEV), etc. It is related with the current sensor used for detecting the electric current which flows through the electric power circuit between.

  For example, in an automobile equipped with this type of electric motor (hereinafter referred to as “motor”), the power terminal of a motor (including a motor generator) or generator and the power terminal of an inverter of a power control unit (PCU) are connected to a relay bus bar. Power circuit (current path) between the motor and the inverter and the inverter is configured, and power is supplied from the battery to the motor via the PCU through the current path (relay bus bar), or from the generator to the inverter The generated power is supplied to the battery through the current path via the (PCU). At this time, a current sensor is attached to the relay bus bar, the current flowing through the relay bus bar is measured by the current sensor, and feedback power (current) control is performed in the PCU based on the comparison between the measured value and the current command value. Control the motor to the required speed and torque.

The current sensor normally detects a change in the magnetic field generated in the notched part (gap) of a partially cut-out annular magnetic core, such as a U-shape, surrounding the bus bar through which current flows as the current path. And a circuit board on which the magnetic sensor is mounted, and a case to which the bus bar, the magnetic core, the magnetic sensor, and the circuit board are attached (see FIG. 1).
The case is the case of the current sensor itself (Patent Document 1), or doubles as a connector housing (Patent Document 2).

JP 2011-209158 A JP 2008-114839 A

In any of the above-described configuration of the current sensor, after the magnetic core, the magnetic sensor, etc. are incorporated in the case, the required current value is changed by the magnetic field fluctuation corresponding to the required current by various resistance adjustments on the circuit board. It is adjusted (trimmed) to be detected. If this adjustment state fluctuates with use, for example, if the position of the magnetic sensor shifts, the reliability of the current sensor decreases, and the hybrid vehicle or the like has a great influence on its running performance.
In particular, in the current sensor in which the magnetic sensor stands up from the circuit board with its legs, the magnetic sensor main body is supported by the legs and suspended in the magnetic core gap. Changes in the positional relationship between the magnetic sensor main body and the magnetic core due to slight bending of the legs or the like.

  Further, the magnetic core is integrally molded at the time of resin molding of the case. This is because, conventionally, the magnetic core is made of a laminated iron plate and has low dimensional accuracy. Therefore, if the magnetic core is fitted and fixed to the case, high attachment accuracy to the case cannot be obtained, and the attachment accuracy is ensured by molding. .

  This invention makes it a subject to prevent the shift | offset | difference (change) of the positional relationship of the magnetic sensor and magnetic body core in use.

As one means for achieving the above object, the present invention is configured to clamp and fix the magnetic sensor to the case. At this time, the magnetic sensor can be clamped by clamping the sensor main body or the leg, but it is preferable to clamp the sensor main body as the detection unit. In the case of a leg, it should be as close to the sensor body as possible.
Thus, if the magnetic sensor is clamped and fixed with the case, the magnetic sensor is less likely to move with respect to the case even if the magnetic sensor stands up with its legs from the circuit board. For this reason, unless the magnetic core moves relative to the case, the positional relationship between the magnetic sensor and the magnetic core is unlikely to shift.

  As a configuration of the present invention, a magnetic core that surrounds a bus bar through which a current flows, a magnetic sensor that has a notch, detects a magnetic field change that occurs in the notch, and a circuit that includes the magnetic sensor A board and a case having a pair of sandwiching pieces facing each other that enter the notch of the magnetic core, the magnetic core and the circuit board being fixed to the case, and the magnetic sensor having the legs It is possible to adopt a configuration in which the magnetic sensor rises from the circuit board and is positioned in the notch portion of the magnetic core, and the magnetic sensor is fitted between the pair of sandwiching pieces of the case and positioned with respect to the magnetic core. it can.

In this configuration, the opposing pair of sandwiching pieces may be separate ones protruding from the case body, or a slit (member) protruding from the case body may be formed as in the following embodiment. It can be formed by opposing side walls. In short, any mode may be used as long as the magnetic sensor can be sandwiched and fixed.
At this time, the gap of the protruding sandwiching piece and the width of the slit are gradually narrowed in the direction of insertion of the magnetic sensor, or narrowed in the middle, and the magnetic sensor is pressed and supported in them. It is preferable to do so.

  Further, the apparatus further includes a cover that covers the case, the magnetic core is fitted and fixed to the case, and the circuit board is fitted to the case so that a plate surface direction thereof is along a length direction of the bus bar, The circuit board may be fixed to the case by the cover penetrating the bus bar and being fixed to the case. In this way, the magnetic core and the circuit board can be attached to the case by fitting, so that the attaching operation becomes easy. At this time, the magnetic core is preferably made of compacted powder with high dimensional accuracy described below.

As another means for achieving the above object, according to the present invention, the magnetic core is fitted and fixed to the outer peripheral surface of the case cylindrical portion through which the bus bar through which the current flows passes.
As described above, if the magnetic core is fitted and fixed to the case cylindrical portion, the positional relationship between the magnetic sensor and the magnetic core is unlikely to shift unless the magnetic sensor is fixed to the case and moved. At this time, it is preferable that the magnetic core is made of compacted powder with high dimensional accuracy.

As a configuration of the present invention, a magnetic core surrounding a bus bar through which a current flows, the magnetic core has a cutout portion, a magnetic sensor for detecting a magnetic field change generated in the cutout portion, and a cylindrical shape through which the busbar penetrates It is possible to adopt a configuration in which the magnetic core is fitted and fixed to the outer surface of the cylindrical portion of the case.
At this time, a rib in the insertion direction of the magnetic core is provided on the outer peripheral surface of the cylindrical portion, and the inner surface of the magnetic core is pressed against the rib to firmly fit and fix the magnetic core in the cylindrical portion. Can do. One or a plurality of ribs may be used.

  A case having a cylindrical portion through which the bus bar passes, and a cover that covers the case and has an insertion piece that enters a wedge shape between the inner surface of the magnetic core and the outer surface of the cylindrical portion. The cover penetrates the bus bar, covers one surface of the magnetic core and is fixed in the case, and the insert piece is inserted into a wedge shape between the inner surface of the magnetic core and the outer surface of the cylindrical portion. The magnetic core can be fixed to the cylindrical portion. In this configuration, since the insertion piece enters between the bus bar and the magnetic core, the creeping insulation distance between the two becomes long (see FIG. 6).

These means can be used in combination with each other. For example, in the other means, the circuit board further includes a circuit board on which the magnetic sensor is mounted. The magnetic sensor rises from the circuit board with its legs and is located in the notch portion of the magnetic core. There may be a pair of opposing sandwiching pieces that enter the notch portion of the magnetic core, and the magnetic sensor is fitted between the pair of sandwiching pieces and positioned with respect to the magnetic core.
Further, both the magnetic sensor and the magnetic core can be fixed to the case by providing a rib on the outer peripheral surface of the case cylindrical portion or providing an insertion piece on the cover.
In the case of a rib, a rib or insertion piece is provided with an inclined surface that gradually increases in the insertion direction so that the rib bites into a wedge shape as the magnetic core is fitted into the cylindrical portion. In the case of an insertion piece, the insertion piece can be bitten like a wedge between the magnetic core and the cylindrical portion as the shape gradually becomes thinner toward the tip.

  The said magnetic body core can be comprised with a laminated iron plate, or can be set as the structure which consists of a powder magnetic body (powder core) which insulated the magnetic powder separately and pressure-molded it. The dust core is suitable for recycling because it exhibits good electromagnetic conversion characteristics in a high frequency band, has a high degree of freedom in molding and is easy to downsize, and has a structure that allows the bus bar to be easily separated. In addition, since the molding core has high molding (dimension) accuracy, it is possible to obtain sufficient mounting accuracy in the case after molding the case without being embedded during molding of the resin case, even if it is fitted and fixed in its storage hole. Can do.

  In each of the current sensors, the bus bar may be penetrated through the case after assembly or may be embedded (molded) through the case when the case is molded with resin. When penetrating after assembling, it is possible to penetrate with flexibility (play). The case may be a connector housing (case). In the case of a male connector, a bus bar is inserted and embedded in a resin case, and the current path is configured by fitting the bus bar as a male piece into a female connector. In the case of a female connector, a bus bar of a female piece is embedded in the case, and a male path of a male connector is fitted into the bus bar to constitute a current path.

  The assembly of the current sensor having these configurations may be performed as appropriate. For example, the magnetic powder core surrounding the bus bar through which the current flows, the magnetic core has a notch, and the magnetic field change generated in the notch is changed. Assembling a current sensor comprising: a magnetic sensor to detect; a circuit board on which the magnetic sensor is mounted; a case having a pair of sandwiching pieces that enter into the cutout portion of the magnetic core; and a cover of the case. If the magnetic sensor is raised from the circuit board with its legs, the magnetic core is fitted and fixed in the case so that the pair of sandwiching pieces enter the notch, and the circuit board is fixed to the plate surface. It is fitted in the case so that the direction is along the length direction of the bus bar, and the magnetic sensor is fitted and fixed between the pair of sandwiching pieces to be positioned in the notch portion of the magnetic core, By fitting the cover secured to the case suffer one side of the sexual core, it is possible to adopt a configuration for fixing the circuit board to the case.

  Since the present invention is configured as described above and the magnetic sensor core and the magnetic core are securely fixed to the case, the positional relationship between the magnetic sensor and the magnetic core is not misaligned during use. A current sensor that hardly occurs can be obtained.

1 is a schematic perspective view of an embodiment of a current sensor according to the present invention. Cutting plan view of the same embodiment Exploded perspective view of the same embodiment The perspective view from the back surface of the case of the embodiment Exploded perspective view of another embodiment Cut side view of the same embodiment The perspective view of each modification of the cover of the embodiment Mounting diagram of magnetic sensor on circuit board in each embodiment

  1 to 4 show an embodiment of the present invention. A current sensor S according to this embodiment is provided between a motor and an inverter of a hybrid vehicle. As shown in FIG. A magnetic core 20 that surrounds the magnetic core 30, a magnetic sensor 30 that detects a magnetic field change that occurs in a notch (gap) 21 of the magnetic core 20, a circuit board 40 for current detection on which the magnetic sensor 30 is mounted, and the bus bar 10 The case 50 includes a case 50 to which the magnetic core 20, the magnetic sensor 30 and the circuit board 40 are attached, and a cover 60 of the case 50.

The case 50 is a resin-molded product such as a bottomed box-like glass fiber-filled PBT (polybutylene terephthalate) resin, and has mounting pieces 51 on both sides thereof. Bolts, nuts and the like are fastened through the holes 52 and fixed to the inverter casing, the motor casing, and other frames. The cover 60 is also a molded product made of the same resin.
A substantially rectangular cylindrical portion 54 is provided from the bottom plate of the case 50 to the height of the side wall (see FIG. 3), and the magnetic core 20 is fitted on the outer peripheral surface of the cylindrical portion 54.

  Ribs 55 in the cylinder axis direction are formed on the outer peripheral surface of the cylindrical portion 54, and the height of each rib 55 gradually increases from the opening of the case 50 toward the bottom surface. When the body core 20 is fitted, a pressure contact force is gradually applied to the magnetic core 20 by the ribs 55, and the magnetic core 20 is firmly supported and fixed to the cylindrical portion 54. The height of the rib 55 may be the same in the length direction (the cylinder axis direction) as long as the magnetic core 20 can be fitted and fixed.

  If there is at least one rib 55, the magnetic core 20 can be supported and fixed. However, in order to make the cylindrical portion 54 and the axis of the magnetic core 20 coincide with each other, at least the four surfaces of the cylindrical portion 54 on the top, bottom, left, and right There are preferably ribs 55 on three sides. In this embodiment, in FIG. 2, ribs 55 are provided on the left and right surfaces and the lower surface, and two ribs 55 are provided on the upper surface. The two ribs 55, 55 on the upper surface are at equal distances on both sides from the slits 56 constituting the following pair of sandwiching pieces, and even if the magnetic core 20 is fitted into the cylindrical portion 54, the slits 56 extend in the length direction. No tilting occurs.

  The slit 56 is composed of standing pieces 56a and 56a that rise from the upper surface of the bottom plate and continue to the cylindrical portion 54, and a bottom plate slit 56b that is formed between the standing pieces. (See FIG. 4). Therefore, as described below, when the magnetic sensor 30 is fitted into the slit 56, the magnetic sensor 30 is pressed against the side wall of the slit 56 (56b) and firmly supported and fixed in accordance with the fitting.

  The bus bar 10 is formed of a straight plate, and a power output terminal from the inverter is connected to one terminal thereof, and a power input terminal of the motor is connected to the other terminal. The connection may be via a cable or by another bus bar, but the terminal may facilitate the connection by incorporating a square nut, press fitting a pierce nut, or the like. Further, the bus bar 10 may be fitted into and fixed to the cylindrical portion 54 of the current sensor case 50, or may be embedded in the case 50 when resin is molded. Further, the current sensor S may be attached to an existing bus bar forming a power circuit from the inverter to the motor (the bus bar may be passed through the cylindrical portion 54 of the case 50).

  The magnetic core 20 is made of a powder magnetic material (a powder core) obtained by press-molding magnetic powder, and the Hall element that is the magnetic sensor 30 is located in the notch (gap) 21. The hall element 30 includes an element body 31 and lead legs 32 and is mounted on a circuit board 40. For example, as shown in FIG. 8, the Hall element 30 is mounted on the circuit board 40 by placing the Hall element 30 in a jig 35, passing the circuit board 40 through the leg 32, and using the jig 35. The circuit board 40 is positioned with respect to the element 32 (element main body 31) (FIG. 5A), a protrusion 32a is formed in the middle of the leg 32, the circuit board 40 is passed through the leg 32, and the leg 32 ( After positioning the circuit board 40 with respect to the element body 31) (FIG. 5B), each leg 32 is connected and fixed to the circuit on the circuit board 40 by reflow or the like, and the Hall element 30 is attached to the circuit board 40. Mounted with the legs 32 standing up.

The circuit board 40 is fitted into the case 50 with the groove 57. With this fitting, the element body 31 of the Hall element 30 enters the slit 56 and is supported and fixed, and is positioned in the gap 21 of the magnetic core 20. At this time, it is preferable that the Hall element body 31 is directly pushed into a required position of the slit 56 by using a pressing element that is integral with or separate from a jig for fitting the circuit board 40. Further, the width of the groove 57 can be gradually narrowed in the direction in which the circuit board 40 is fitted (both wall surfaces are tapered surfaces), and the circuit board 40 can be pressed and supported to be firmly fixed.
Thereafter, the circuit board 40 is pressed and fixed to the case 50 by fitting the resin cover 60 to the case 50. The cover 60 has fitting pieces 61, 61 at both ends, and the fitting pieces 61, 61 are attached to the case 50 by engaging the engaging protrusions 59 on the side surface of the case 50.

  The current sensor S assembled in this way is provided in at least two phases of the current path between the motor and the inverter of the hybrid vehicle. For this reason, when a current flows through the phase (bus bar 10), the Hall element 30 detects a magnetic field change generated in the core cutout portion 21 in accordance with a change in the current flowing through the bus bar 10, and the circuit board 40 is based on the detection signal. The current measurement value is sent to the PCU of the inverter through the connector 41 and the like. Note that when the current circuit between the motor and the inverter of the hybrid vehicle has three phases and the current sensor S is provided in the two phases, the current value of the other phase is the detected value of the two phases. Calculate from (current value).

  Other embodiments are shown in FIGS. 5 and 6. In this embodiment, a rectangular frame-shaped insertion piece 62 is formed on the surface of the cover 60 facing the case 50. The entire outer periphery of the insertion piece 62 becomes a tapered surface that gradually decreases toward the case 50, and a notch 63 into which the slit portion (standing piece 56a) of the case enters is formed on one surface of the insertion portion. Therefore, as shown in FIG. 6, when the cover 60 is attached to the case 50, the insertion piece 62 enters a wedge shape between the inner surface of the magnetic core 20 and the outer surface of the cylindrical portion 54, and the cylindrical portion 54 has a magnetic property. The body core 20 is firmly fixed. In this embodiment, as shown in FIG. 6, since the resin insertion piece 62 enters between the bus bar 10 and the magnetic core 20, the creeping insulation distance between the both 10 and 20 is increased. For example, a creeping insulation distance of 10 mm or more can be easily obtained.

In this embodiment as well, when a current flows through the bus bar 10, the Hall element 30 detects a change in the magnetic field generated in the core cutout portion 21 in response to a change in the current flowing through the relay bus bar 10 and detects the change. Based on the signal, the measured current value is sent from the circuit board 40 to the PCU of the inverter through the connector 41 and the like.
If the cover 60 interferes with trimming, the magnetic core 20 is temporarily fixed to the case 50, and trimming is performed in the temporarily fixed state. Thereafter, the cover 60 is fitted into the case 50, or the cover 60 is attached to the cover 60. Trimming holes are formed.

In this embodiment, even if the insertion piece 62 is not cylindrical, it suffices if the magnetic core 20 can be fixed to the cylindrical portion 54, so that it enters one surface of the inner peripheral surface of the core 20 shown in FIG. It is assumed that it is a plate piece, a shape that enters into two surfaces consisting of two opposing plate pieces as shown in (b), or a shape that enters into three surfaces with a U-shaped cross section as shown in (c). obtain. In short, any mode may be used as long as it enters a wedge shape between the case cylindrical portion 54 and the magnetic core 20 and can fix both.
Also, ribs in the insertion direction can be provided on the inner surface, outer surface, or inner / outer surface of the insertion piece 62. The height of the rib may be gradually lowered toward the insertion direction. At this time, the insertion pieces can have the same thickness (the same width in the vertical direction) in the protruding direction. Further, the rib 55 can be provided on the outer peripheral surface of the case cylindrical portion 54.

In each embodiment, the shape of the magnetic core 20 is not limited to a U shape, and may be any shape such as a circle and an ellipse. Further, the bus bar 10 may have a rod shape such as a square shape, a circular shape, or an elliptical shape, instead of a flat plate shape having a square cross section as in the above embodiment.
The means for supporting and fixing the magnetic sensor 30 to the case 50 is not limited to the one-phase (one bus bar 10) in the above embodiment, but the current sensor S includes two, three,. Of course, it can be adopted. In addition, the current sensor S of the present invention is not limited to the current path between the motor and the inverter of the automobile, but can be used for current detection of other various current paths.
Furthermore, the magnetic sensor is not limited to a Hall element, and conventionally known sensors such as a Hall IC and a magnetoresistive element can be appropriately employed.

  The cover 60 is formed with a projecting piece positioned in the core gap 21, and the projecting piece is formed with a gap (slit) in which the magnetic sensor 30 is fitted and positioned to support positioning of the magnetic sensor 30. Can be fixed. The slit includes a case where the slits are formed of opposing clamping pieces. Further, in each of the above embodiments, if the circuit board 40 is screwed to the case 50, it is not necessary to fix the circuit board 40 to the case 50 with the cover 60, and the cover 60 can be omitted.

  Thus, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

10 Busbar 20 Magnetic Core 21 Magnetic Core Notch (Gap)
30 Magnetic sensor (Hall element)
31 Hall element body 32 Hall element lead leg 40 Circuit board 50 Case 54 Case cylindrical part 55 Case cylindrical part outer peripheral surface 56 Case slit forming a pair of clamping pieces 60 Cover 62 Cover insertion piece

Claims (9)

A magnetic core surrounding a bus bar through which current flows, the magnetic core having a notch, a magnetic sensor for detecting a magnetic field change generated in the notch, a circuit board on which the magnetic sensor is mounted, and the magnetic core And a case having a pair of opposing sandwiching pieces that enter the cutout portion of
The magnetic core and the circuit board are fixed to the case, and the magnetic sensor rises from the circuit board with its legs and is located in the cutout portion of the magnetic core, and is interposed between the pair of holding pieces of the case. A current sensor, wherein a magnetic sensor is fitted and positioned with respect to a magnetic core.   2. The current sensor according to claim 1, further comprising a cover that covers the case, wherein the magnetic core is fitted and fixed to the case, and a plate surface direction of the circuit board is along a length direction of the bus bar. Thus, the circuit board is fixed to the case by being fitted into the case and the cover penetrating the bus bar and being fixed to the case. A magnetic core surrounding a bus bar through which a current flows, the magnetic core having a notch, a magnetic sensor for detecting a magnetic field change generated in the notch, and a case having a cylindrical portion through which the bus bar passes. ,
The current sensor, wherein the magnetic core is fitted and fixed to the outer surface of the cylindrical portion of the case.   The rib is formed in the fitting direction on the outer surface of the cylindrical portion, and the magnetic core is fixed to the cylindrical portion by pressing the magnetic core against the rib. Current sensor.   The current sensor according to claim 4, wherein a height of the rib is gradually increased in a direction in which the magnetic core is fitted. A magnetic core surrounding a bus bar through which a current flows, the magnetic core has a notch, a magnetic sensor for detecting a magnetic field change generated in the notch, a case having a cylindrical portion through which the bus bar passes, and A cover for the case, and a cover having an insertion piece that enters a wedge shape between the inner surface of the magnetic core and the outer surface of the cylindrical portion,
The cover penetrates the bus bar, covers one surface of the magnetic core, and is fitted and fixed to the case. The insert piece is wedge-shaped between the inner surface of the magnetic core and the outer surface of the cylindrical portion. A current sensor, wherein the magnetic core is fixed to the cylindrical portion by being inserted.   The current sensor according to any one of claims 3 to 6, further comprising a circuit board on which the magnetic sensor is mounted, wherein the magnetic sensor rises from the circuit board with its legs and is in a notch portion of the magnetic core. The case includes a pair of opposing sandwiching pieces that enter the notch portion of the magnetic core, and the magnetic sensor is fitted between the pair of sandwiching pieces to the magnetic core. A current sensor characterized by being positioned.   The current sensor according to claim 1, wherein the magnetic core is made of a dust magnetic material. A magnetic powder core surrounding a bus bar through which a current flows, the magnetic core having a notch, a magnetic sensor for detecting a magnetic field change generated in the notch, a circuit board on which the magnetic sensor is mounted, and the magnetic A method of assembling a current sensor comprising a case having a pair of opposing sandwiching pieces that enter the notch of the body core, and a cover of the case,
The magnetic sensor rises from the circuit board with its legs, and the magnetic core is fitted and fixed in the case so that the pair of sandwiching pieces enter the notch, and the circuit board is fixed to the plate surface. The magnetic core is fitted into the case so that the direction is along the length direction of the bus bar, and the magnetic sensor is fitted and fixed between the pair of sandwiching pieces to be positioned in the notch of the magnetic core. A method of assembling a current sensor, comprising: fixing the circuit board to the case by fitting the cover into the case and fixing the cover.

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