JP2012042409A - Current detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an electronic component from falling into a failure by a high voltage applied from a busbar and to attain reduction in size compatibly in a current detection apparatus for detecting a current flowing to the busbar.SOLUTION: A current detection apparatus 1 includes a housing 40 maintaining components of a magnetic substance core 10, a current detection busbar 30 and a hole element 20 disposed in a gap part 11 of the magnetic substance core 10 in a fixed positional relationship. The housing 40 comprises a cover member 42 of a conductor and a main body case 41 of an insulator which are combined with each other to hold the components. The cover member 42 of the conductor is a heat radiating part in contact with the current detection busbar 30.

Description

  The present invention relates to a current detection device that detects a current flowing in a bus bar.

  A vehicle such as a hybrid vehicle or an electric vehicle is often equipped with a current detection device that detects a current flowing through a bus bar connected to a battery. As such a current detection device, a magnetic proportional current detection device or a magnetic balance current detection device may be employed.

  For example, as disclosed in Patent Document 1, a magnetic proportional type or magnetic balance type current detection device includes a magnetic core and a magnetoelectric conversion element (magnetic sensitive element). The magnetic core is a generally ring-shaped magnetic body formed in a series surrounding both sides of a hollow portion where both ends face each other through a gap portion and the bus bar passes therethrough. The hollow portion of the magnetic body is a space (current detection space) through which a current to be detected passes.

  The magnetoelectric conversion element is disposed in the gap portion of the magnetic core, detects a magnetic flux that changes according to the current flowing through the bus bar disposed through the hollow portion, and outputs a detection signal of the magnetic flux as an electric signal. It is an element. As the magnetoelectric conversion element, a Hall element is usually adopted.

  As shown in Patent Document 1, in a conventional current detection device, a magnetic core, a bus bar, and a magnetoelectric conversion element are often held in a fixed positional relationship by an insulating casing. The casing is made of a member such as resin, and positions a plurality of components constituting the current detection device in a fixed positional relationship.

JP 2009-128116 A

  By the way, in a current detection device mounted on a vehicle such as an electric vehicle and a hybrid vehicle, there is an increasing demand for downsizing of the device, and the current flowing through the bus bar is increasing. Therefore, the bus bar in recent vehicles tends to generate heat and become high temperature.

  Under the condition that a sufficient distance cannot be provided between the bus bar and each component constituting the current detection device due to space constraints, the conventional current detection device has the following problems. is doing. The first problem is that the resin casing that holds the bus bar and the component parts in a certain positional relationship is excessively heated and deformed due to heat generated by the bus bar. The second problem is that the current detection characteristic of the current detection device changes due to a change in environmental temperature due to heat generated by the bus bar, and the change in the characteristic causes an increase in current detection error.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a current detection device for detecting a current flowing through a bus bar, which can avoid the deformation of the casing and the increase in current detection error due to the high temperature of the bus bar without increasing the size of the device.

The current detection device according to the present invention includes the following components.
(1) The first component is a magnetic core formed in a series surrounding the periphery of a hollow portion through which a bus bar through which a current flows, with both ends opposed via a gap portion.
(2) A 2nd component is a magnetoelectric conversion element which detects the magnetic flux which is arrange | positioned at a gap part and changes according to the electric current which passes a hollow part.
(3) The third component is a housing that holds the magnetic core, the bus bar, and the magnetoelectric conversion element in a fixed positional relationship, and includes a heat radiating portion that is at least partially made of a conductor that contacts the bus bar.

  Further, in the current detection device according to the present invention, the casing is composed of a conductor member and an insulator member that hold the magnetic core, the bus bar, and the magnetoelectric conversion element in a fixed positional relationship by being combined with each other. The conductor member may be a heat radiating part.

  Further, in the current detection device according to the present invention, the housing holds the magnetic core, the bus bar, and the magnetoelectric conversion element in a fixed positional relationship, and the portion that penetrates the hollow portion of the magnetic core and the bus bar and the magnetoelectric conversion It is conceivable to cover the element.

  In the current detection device according to the present invention, the housing that holds the magnetic core, the bus bar, and the magnetoelectric conversion element in a certain positional relationship functions as a heat sink that dissipates heat generated by the bus bar. Therefore, according to the present invention, it is possible to prevent the bus bar from being excessively heated, and to avoid the deformation of the casing and the increase in current detection error due to the high temperature of the bus bar.

  In addition, if the casing is composed of conductor members (heat dissipating parts) and insulator members that are combined with each other, insulation with members around the current detection device is ensured, and the weight of the device is reduced. This is preferable.

  Moreover, when a housing | casing covers a part of bus bar, a magnetic body core, and a magnetoelectric conversion element, the part in the housing | casing in a bus bar tends to heat up and heat up more easily than another part. Therefore, if the housing disposed in the portion of the bus bar that is particularly prone to high temperature functions as a heat sink, the effect of preventing the high temperature of the bus bar is further enhanced.

It is a disassembled perspective view of the electric current detection apparatus 1 which concerns on embodiment of this invention. FIG. 3 is a three-side view of a current detection bus bar 30 provided in the current detection device 1. 4 is a plan view of a member that is a source of the current detection bus bar 30. FIG. 1 is a plan view of a current detection device 1. FIG. 1 is a cross-sectional view of a current detection device 1. FIG. It is a perspective view which shows typically a mode that the electric current detection apparatus 1 is connected with the bus bar laid beforehand.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example embodying the present invention, and is not an example of limiting the technical scope of the present invention.

  First, the configuration of the current detection device 1 according to the embodiment of the present invention will be described with reference to FIGS. The current detection device 1 is a device that detects a current flowing through a bus bar that electrically connects a battery and a device such as a motor in a vehicle such as an electric vehicle or a hybrid vehicle. As shown in FIG. 1, the current detection device 1 includes a magnetic core 10, a Hall element 20, a current detection bus bar 30, a housing 40, and an electronic substrate 50.

<Magnetic core>
The magnetic core 10 is a magnetic body made of ferrite, silicon steel, or the like, and has both ends opposed to each other via a gap portion 12 of about several millimeters and a series of shapes surrounding the hollow portion 11. ing. In other words, the magnetic core 10 has a narrow gap portion 12 but is formed in a generally annular shape. The magnetic core 10 in this embodiment is formed in an annular shape surrounding the circular hollow portion 11.

<Hall element (magnetoelectric conversion element)>
The Hall element 20 is disposed in the gap portion 12 of the magnetic core 10, detects a magnetic flux that changes according to a current passing through the hollow portion 11 of the magnetic core 10, and outputs a magnetic flux detection signal as an electric signal. It is an example of a conversion element.

<Electronic board>
The electronic board 50 is a printed circuit board on which the Hall element 20 is mounted at the terminal 21 portion. In addition to the Hall element 20, a circuit that amplifies a magnetic flux detection signal output from the Hall element 20 and a connector 51 that connects the circuit and other external circuits are mounted on the electronic substrate 50. Yes. Therefore, the connector 51 is electrically connected to the Hall element 20, and the Hall element 20 is connected to an external circuit via the electronic substrate 50 including the connector 51.

<Bus bar for current detection>
The current detection bus bar 30 is a conductor made of a metal such as copper, and is a part of the bus bar that electrically connects the battery and the electrical equipment. That is, a current to be detected flows through the current detection bus bar 30. The current detection bus bar 30 is a member independent of the battery-side bus bar connected in advance to the battery and the device-side bus bar connected in advance to the electrical equipment. The current detection bus bar 30 is connected to other bus bars (battery-side bus bar and device-side bus bar) laid at both ends thereof in advance.

  In FIG. 2, which is a three-view diagram of the current detection bus bar 30, FIG. 2 (a) is a plan view, FIG. 2 (b) is a side view, and FIG. 2 (c) is a front view. In FIG. 2, the magnetic core 10 combined with the current detection bus bar 30 is indicated by a virtual line (two-dot chain line).

  As shown in FIGS. 1 and 2, the current detection bus bar 30 is generally composed of a first portion 31 occupying a certain range in the central portion and second portions 32 on both sides thereof. The 1st part 31 is a part which penetrates the hollow part 11 of the magnetic body core 10 along an electric current passage direction. The current passing direction is the thickness direction of the magnetic core 10, the axial direction of the cylinder when the annular magnetic core 10 is regarded as a cylinder, and further on the surface formed by the annular magnetic core 10. It is also an orthogonal direction. In each figure, the current passing direction is indicated as the X-axis direction. In the following description, the current passing direction (X-axis direction) is referred to as a first direction.

  The current detection bus bar 30 includes a first portion 31 that penetrates the hollow portion 11 of the magnetic core 10 along the first direction, and a flat plate-like second portion that is continuous with both sides of the first portion 31 in the first direction. This is a member made of a conductor formed with a portion 32. In each figure, the width direction and the thickness direction of the flat plate-like second portion 32 are described as a Y-axis direction and a Z-axis direction, respectively. In the following description, the width direction (Y-axis direction) and the thickness direction (Z-axis direction) of the flat plate-like second portion 32 are referred to as a second direction and a third direction, respectively.

  As shown in FIG. 3, the current detecting bus bar 30 includes a portion 31Y of the flat metal member 30Y along cuts 34 formed on both sides in the first direction (X-axis direction) of the portion 31Y. It is a member having a structure folded from both sides in the second direction (Y-axis direction). The notches 34 in the metal member 30Y are formed from both ends in the second direction (Y-axis direction) toward the inside on both sides in the first direction (X-axis direction) of the portion 31Y. The folded portion 31Y constitutes the first portion 31 of the current detection bus bar 30, and the portions on both sides of the folded portion 31Y constitute the second portion 32. Such a current detection bus bar 30 can be easily manufactured.

  In the current detection bus bar 30, the contour shape of the cross section of the first portion 31 is constricted in the second direction (Y-axis direction) with respect to the second portion 32. As a result, by using the current detection bus bar 30 in the current detection device 1, it is possible to employ a relatively small magnetic core 10 in relation to the width of the bus bar, and the entire device including the magnetic core 10. Can be avoided.

  Further, in the current detection bus bar 30, the cross-sectional contour shape of the first portion 31 is formed such that the minimum width D4 is larger than the thickness D6 (minimum width) of the second portion 32. Thereby, the cross-sectional area of the conductor in the first portion 31 is not significantly reduced as compared with the cross-sectional area of the conductor in the second portion 32. In particular, in the current detection bus bar 30 having a structure in which a part of the flat metal member 30Y is folded, the cross-sectional area of the conductor in the first portion 31 and the cross-sectional area of the conductor in the second portion 32 are the same. is there.

  However, in the current detection bus bar 30, the conductor cross-sectional area of the portion where the notch 34 is formed between the first portion 31 and the second portion 32 is smaller than the cross-sectional area of the conductor in the front and rear portions. Become. However, as a result of experiments, it has been found that when the width of the notch 34 is very narrow, the increase in impedance at the portion where the notch 34 is formed is small enough to be ignored for the current detection bus bar 30 as a whole. . Therefore, in the current detection bus bar 30, when the very narrow cut 34 is formed, excessive heat generation in the first portion 31 can be prevented.

  The second portion 32 of the current detection bus bar 30 is formed with a screwing hole 32Z through which a screw for connection with another bus bar is passed. The 2nd part 32 in which this hole 32Z was formed is a terminal part connected with another bus bar.

  FIG. 6 is a perspective view schematically showing a state in which the second portion 32 (terminal portion) of the current detection bus bar 30 in the current detection device 1 is connected to another bus bar 9 laid in advance by screws 8. It is. In FIG. 6, the housing 40 is not shown for convenience. As shown in FIG. 6, the portion connected to the second portion 32 of the current detection bus bar 30 in the other bus bar 9 has, for example, a structure as a terminal block, and a screw fixing hole 9 </ b> A is formed. ing. In addition, the terminal part formed in the 2nd part 32 can also have other structures, such as a fitting mechanism with the other bus-bar 9, besides the hole 32Z for screwing.

<Case>
The housing 40 is a member that holds the magnetic core 10, the current detection bus bar 30, and the electronic substrate 50 on which the Hall element 20 is mounted in a fixed positional relationship, and includes a main body case 41 that is an insulator, And a lid member 42 which is a conductor attached to 41.

  The main body case 41 is an integrally molded member made of an insulating resin such as polyamide (PA), polypropylene (PP), or ABS resin. On the other hand, the lid member 42 is an integrally molded member made of a metal such as copper or aluminum.

  The body case 41 is formed in a box shape having an opening, and the lid member 42 closes the opening of the body case 41 by being attached to the body case 41. The main body case 41 is formed with a first holding portion 43 and a second holding portion 44 that protrude on the inner surface thereof. The main body case 41 includes the first holding portion 43 and the second holding portion 44, the magnetic core 10, the current detection bus bar 30 penetrating the hollow portion 11, and the Hall element 20 disposed in the gap portion 12. Are held in a state where they are not in contact with each other.

  More specifically, the first holding portion 43 is fitted into the gap between the magnetic core 10 and the first portion 31 of the current detection bus bar 30 that penetrates the hollow portion 11, thereby causing the magnetic core 10 and the current to pass through. The detection bus bars 30 are held in a state where they do not contact each other. Further, the second holding portion 44 fits into the gap between the magnetic core 10 and the Hall element 20 disposed in the gap portion 12, thereby bringing the magnetic core 10 and the Hall element 20 into contact with each other. Hold in a state that does not.

  The main body case 41 and the lid member 42 are formed with slit holes 45 into which the second portions 32 at both ends of the current detection bus bar 30 are inserted from the inside to the outside. In the state where one second portion 32 of the current detection bus bar 30 penetrating through the hollow portion 11 of the magnetic core 10 is passed through the slit hole 45 of the main body case 41, The two holding portions 44 hold the magnetic core 10, the Hall element 20, and the current detection bus bar 30 in a fixed positional relationship in a state where they are not in contact with each other.

  The lid member 42 is attached to the main body case 41 holding the magnetic core 10, the Hall element 20 and the current detection bus bar 30 so as to close the opening of the main body case 41 while sandwiching the electronic substrate 50. At this time, the other second portion 32 of the current detection bus bar 30 is passed from the inside to the outside with respect to the slit hole 45 of the lid member 42, and the electronic substrate 50 is sandwiched between the main body case 41 and the lid member 42. It is.

  4 and 5 are a plan view and a cross-sectional view of the current detection device 1 in a state where the main body case 41 and the lid member 42 are combined. As shown in FIGS. 4 and 5, the electronic substrate 50 is sandwiched between the main body case 41 and the lid member 42, so that the connector 51 mounted on the electronic substrate 50 is not formed in the main body case 41. It is held in a state of being fitted into the portion 46.

  Furthermore, the main body case 41 and the lid member 42 are provided with lock mechanisms 47 and 48 that hold them in a combined state. The lock mechanisms 47 and 48 shown in FIG. 1 include a claw portion 47 formed to project from the side surface of the main body case 41 and an annular frame portion 48 formed on the side of the lid member 42. When the claw portion 47 of the main body case 41 is fitted into the hole formed by the frame portion 48 of the lid member 42, the main body case 41 and the lid member 42 are held in a state where they are combined. As described above, the housing 40 holds the magnetic core 10, the current detection bus bar 30, and the Hall element 20 mounted on the electronic substrate 50 in a fixed positional relationship.

  As shown in FIGS. 1 and 5, two bus bar contact portions 49 a and 49 b that contact the current detection bus bar 30 are formed on the inner surface of the lid member 42 constituting the housing 40 so as to protrude. ing. The two bus bar contact portions 49 a and 49 b are provided opposite to the edge of the slit hole 45 and sandwich the current detection bus bar 30 passed through the slit hole 45.

  In the example shown in FIG. 5, one bus bar contact portion 49 b abuts on the current detection bus bar 30 and can be elastically deformed by its flexibility in a direction perpendicular to the longitudinal direction of the current detection bus bar 30. It is formed in a plate shape. That is, one bus bar contact portion 49b is formed in a leaf spring shape that elastically biases the current detection bus bar 30 against the other bus bar contact portion 49a. As a result, the two bus bar contact portions 49a and 49b are stably in contact with the current detection bus bar 30, and a contact failure is avoided.

  In addition to the bus bar contact portions 49a and 49b, a protrusion for positioning a component housed in the housing 40 is formed on the inner surface of the lid member 42. In FIG. Description of protrusions other than the contact portions 49a and 49b is omitted.

  As shown in FIGS. 4 and 5, the main body case 41 and the lid member 42 (housing 40) have a portion (terminal portion) in which the hole 32 </ b> Z is formed in the second portion 32 of the current detection bus bar 30. The magnetic core 10, the first portion 31 of the current detection bus bar 30, and the Hall element 20 are covered and held in a state where the connector 51 of the electronic substrate 50 is exposed to the outside.

  In the current detection device 1 described above, the lid member 41 has a high thermal conductivity in the case 40 that contacts the magnetic core 10 and the current detection bus bar 30 and holds the Hall element 20 in a certain positional relationship. It is a conductor. Therefore, the lid member 41 functions as a heat sink that dissipates heat generated by the current detection bus bar 30. Therefore, according to the current detection device 1, it is possible to prevent the current detection bus bar 30 from being excessively heated, and to avoid deformation of the main body case 41 and increase in current detection error due to the temperature increase of the current detection bus bar 30. Can do.

  Further, in the current detection device 1, the housing 40 includes an insulating body case 41 and a conductor lid member 42 that are combined with each other. Therefore, at least on the main body case 41 side, it is preferable in that insulation with surrounding members can be secured. Further, the apparatus can be reduced in weight compared to the case where the entire housing 40 is made of metal.

  In addition, the current detection device 1 in which the magnetic core 10, the current detection bus bar 30, the Hall element 20, and the electronic substrate 50 are held in a fixed positional relationship by the housing 40 is attached to the front and rear bus bars laid in advance. Is easy.

  Further, in the current detection device 1, the casing 40 covers a part of the current detection bus bar 30, the magnetic core 10, and the Hall element 20, so that the current detection bus bar disposed in the casing 40 is used. The first portion 31 of 30 is more likely to be heated and heated than other portions of the entire bus bar. In the current detection device 1, the housing 40 disposed in a portion of the bus bar that is particularly susceptible to high temperatures functions as a heat sink.

  In the embodiment described above, the housing 40 is constituted by the main body case 41 that is an insulator and the lid member 42 that is a conductor. However, it is also conceivable that the housing 40 includes a main body case 41 that is a conductor and a lid member 42 that is an insulator. In this case, the bus bar contact portions 49 a and 49 b are formed on the inner surface of the main body case 41. The current detection device having such a configuration also has the same effect as the current detection device 1 described above. Of course, it is also conceivable that both the main body case 41 and the lid member 42 are conductors.

DESCRIPTION OF SYMBOLS 1 Current detection apparatus 8 Screw 9 Other bus bar 10 Magnetic body core 11 Hollow part 12 Gap part 20 Hall element 21 Terminal 30 Current detection bus bar 30Y Metal member 31 1st part 32 2nd part (terminal part)
32Z hole 34 notch 40 housing 41 main body case 42 lid member 43 first holding part 44 second holding part 45 slit hole 47 claw part (locking mechanism)
48 Frame (locking mechanism)
49a, 49b Bus bar contact part 50 Electronic board 51 Connector

Claims (3)

Magnetic cores formed in a series around the periphery of the hollow portion through which the both ends face each other through the gap and the bus bar through which current flows passes,
A magnetoelectric transducer that is disposed in the gap portion and detects a magnetic flux that changes in accordance with a current passing through the hollow portion;
A case that includes a heat dissipation portion that is formed of a conductor that holds the magnetic core, the bus bar, and the magnetoelectric conversion element in a fixed positional relationship and is in contact with the bus bar at least in part.
A current detection device comprising:   The casing is composed of a conductor member and an insulator member that hold the magnetic core, the bus bar, and the magnetoelectric transducer in a certain positional relationship by being combined with each other, and the conductor member is The current detection device according to claim 1, wherein the current detection device is a heat dissipation unit.   The housing holds the magnetic core, the bus bar, and the magnetoelectric conversion element in a fixed positional relationship, and includes a portion that penetrates the hollow portion of the magnetic core and the bus bar, and the magnetoelectric conversion element. The current detection device according to claim 1, wherein the current detection device covers the current detection device.

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