JP2021085732A - Current measuring device - Google Patents

Abstract

To provide a current measuring device with which it is possible to prevent the heat generated in a shunt resistor from spreading to a circuit board.SOLUTION: In a current measuring device 20, a shunt resistor 21 and a circuit board 31 are integrated in a state where both faces in a thickness direction D1 of a resistive element 22 and extension faces M1, M2 of first and second mounting faces 34a, 34b of the circuit board 31 intersect each other. In a plan view in which the shunt resistor 21 and the circuit board 31 are seen from the outside in a widthwise direction W, the shunt resistor 21 and the circuit board 31 do no overlap, and in a plan view in which the shunt resistor 21 and the circuit board 31 are seen from the outside in the thickness direction D1, the shunt resistor 21 and the circuit board 31 do no overlap.SELECTED DRAWING: Figure 5

Description

The present invention relates to a current measuring device having a shunt resistor and a circuit board.

In a device equipped with a battery and a load driven by the battery as a power source, the current of the battery is measured for the purpose of determining whether or not an overcurrent has occurred and estimating the charge rate of the battery. .. As the current measuring device, there is a current measuring device using a shunt resistor (see, for example, Patent Document 1).

As shown in FIG. 7, the current measuring device 80 of Patent Document 1 includes a shunt resistor 81 and a circuit board 82. The shunt resistor 81 includes a resistor 81a and a pair of electrodes 82b that are joined so as to sandwich the resistor 81a. The circuit board 82 is erected perpendicularly to the shunt resistor 81, and the mounting surface 82a of the circuit board 82 is orthogonal to both sides of the shunt resistor 81 in the thickness direction. Electronic components (not shown) are mounted on the mounting surface 82a of the circuit board 82. The circuit board 82 of the current measuring device 80 is housed inside the case 83, and the shunt resistor 81 is fixed to the case 83 so as to close the opening of the case 83.

JP-A-2018-48840

However, in the current measuring device 80 of Patent Document 1, when a current flows through the shunt resistor 81 and heat is generated in the shunt resistor 81, the circuit board 82 existing at the discharge destination of the heat from the shunt resistor 81 The heat will reach you.

An object of the present invention is to provide a current measuring device capable of making it difficult for heat generated by a shunt resistor to reach a circuit board.

The current measuring device for solving the above problem is a current measuring device provided in the current path, and is a flat plate-shaped resistor and a parallel direction which is one direction intersecting the thickness direction of the resistor. It has a shunt resistor having a pair of electrode terminals sandwiching the resistor along the same, and a circuit board in which a control unit for measuring the voltage of the pair of electrode terminals of the resistor is arranged on a mounting surface. The shunt resistor and the circuit board are integrated in a state where both sides of the resistor in the thickness direction and the extension surfaces of the mounting surface of the circuit board intersect with each other. Assuming that the direction orthogonal to the thickness direction and the juxtaposition direction of the body is the width direction, the shunt resistor and the circuit board are viewed from the outside of the width direction when the shunt resistor and the circuit board are viewed from the outside. The gist is that the shunt resistor and the circuit board do not overlap with each other in a plan view of the shunt resistor and the circuit board from the outside in the thickness direction.

According to this, when a current flows through the shunt resistor, the resistor and the electrode terminals generate heat, but there is no circuit board at the heat dissipation destination along the thickness direction and the heat dissipation destination along the width direction of the shunt resistor. Therefore, the heat generated by the shunt resistor is unlikely to reach the circuit board.

Further, regarding the current measuring device, a metal connecting member is connected to the electrode terminal of the shunt resistor and the conductive portion of the control unit in the circuit board, and the connecting member is fastened to the electrode terminal. It has a flat plate-shaped resistance-side connecting portion and a flat-plate-shaped substrate-side connecting portion to be fastened to the conductive portion, and the side view of the connecting member viewed from the outside in the parallel arrangement direction is L-shaped. The shunt resistor and the circuit board may be integrated by a connecting member.

According to this, the heat generated by the shunt resistor is transferred from the electrode terminal to the conductive portion via the resistance side connection portion and the substrate side connection portion, and is transmitted from the conductive portion to the circuit board. Is a separate body, so heat transfer to the circuit board can be suppressed. Further, the metal connecting member enables electrical connection between the electrode terminal and the conductive portion. For this reason, it is possible to eliminate problems due to thermal influence such as cracks in the solder due to thermal influence, as in the case where the electrode terminal and the conductive portion are electrically connected by solder, for example.

Further, regarding the current measuring device, the circuit board includes the mounting surface on which the control unit is arranged as a first mounting surface on one surface in the thickness direction, and the other surface in the thickness direction of the connecting member. A second mounting surface on which a board-side connecting portion is arranged is provided, and the board-side connecting portion has a substrate-side end surface at a position farthest from the shunt resistor along the second mounting surface, and the second mounting portion is provided. The electronic component may be mounted at a position closer to the shunt resistor than the substrate side end surface along the mounting surface.

According to this, since the shunt resistor does not overlap the circuit board in either the plan view or the front view, the electronic component mounted at a position closer to the shunt resistor than the substrate side end surface on the second mounting surface. Even so, the effect of heat generated by the shunt resistor can be reduced.

Further, with respect to the current measuring device, in the plan view, the shunt resistor projects from the second mounting surface in the width direction, and the protruding dimension of the electronic component mounted on the second mounting surface from the second mounting surface. May be larger than the protrusion dimension of the electronic component mounted on the first mounting surface from the first mounting surface and smaller than the protrusion dimension of the shunt resistor from the second mounting surface.

According to this, since the shunt resistor protrudes in the width direction from the second mounting surface in a plan view, current measurement is performed even if the protruding dimension of the electronic component is large as long as it is within the width direction of the shunt resistor. The device does not become large. Further, by making the protruding dimension of the electronic component mounted on the first mounting surface smaller than the protruding dimension of the electronic component mounted on the second mounting surface, it is not necessary to increase the size of the current measuring device.

Further, in the current measuring device, the electrode terminal and the connecting member are fastened in the polymerization direction, an elastic member is interposed between the electrode terminal and the connecting member in the polymerization direction, and the elastic member is the electrode. The thermal resistance may be higher than that of the terminal.

According to this, when a current flows through the shunt resistor, the electrode terminals generate heat and thermally expand. Even if the electrode terminal thermally expands in the polymerization direction while the electrode terminal and the connecting member are fastened in the polymerization direction, the thermal expansion of the electrode terminal causes the elastic member to expand in the polymerization direction so that the thickness of the elastic member becomes thinner. It is absorbed by elastic deformation. Further, since the thermal resistance of the elastic member suppresses the heat conduction from the electrode terminal to the connecting member, the heat conduction to the circuit board can be suppressed.

According to the present invention, the heat generated by the shunt resistor can be made difficult to reach the circuit board.

The perspective view which shows the battery module. An exploded perspective view showing a current measuring device and a case. The perspective view which shows the shunt resistor and the circuit board. A cross-sectional view showing a current measuring device and a case. Side sectional view showing a current measuring device and a case. A plan sectional view showing a current measuring device and a case. The figure which shows the background technology.

Hereinafter, an embodiment in which the current measuring device is embodied will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the battery pack 10 includes a plurality of secondary batteries 12 in the pack case 11. As the secondary battery 12, any battery such as a lithium ion battery or a nickel hydrogen battery that can be charged and discharged may be used. The plurality of secondary batteries 12 are connected in series. The plurality of secondary batteries 12 may be connected in parallel, or may be connected in series, or a plurality of secondary batteries 12 connected in parallel may be connected in series or in parallel. That is, the connection mode between the plurality of secondary batteries 12 is arbitrary.

The battery pack 10 is mounted as a power source for EVs and PHVs. The battery pack 10 stores power supplied to a load such as a motor. The direction in which the plurality of secondary batteries 12 are lined up coincides with the longitudinal direction of the pack case 11.

The battery pack 10 includes a current measuring device 20 provided in the power path from the battery pack 10 to the load. The current measuring device 20 measures the current flowing in the current path to the load. The current measuring device 20 is housed in a case 13 attached to the battery pack 10. The case 13 is attached to a mounting surface 11a, which is one end surface of both end faces in the longitudinal direction of the pack case 11. The mounting surface 11a has a flat surface shape and is a surface orthogonal to the axis L extending in the longitudinal direction of the pack case 11.

As shown in FIG. 2, the case 13 has a bottomed box-shaped first case member 14 made of metal and a covered tubular second case member 15 made of synthetic resin. The first case member 14 includes a rectangular plate-shaped bottom plate 14a, a first peripheral wall 14b erected from the edge of the bottom plate 14a in a square tubular shape, a plurality of board mounting bosses 14c erected from the bottom plate 14a, and a first. It has a case mounting boss 14d located at four corners of the peripheral wall 14b and erected from the bottom plate 14a. Female screws (not shown) are provided on the inner peripheral surfaces of the board mounting boss 14c and the case mounting boss 14d.

The second case member 15 that closes the opening of the first case member 14 includes a rectangular plate-shaped lid plate 15a, a second peripheral wall 15b that stands upright from the edge of the lid plate 15a in a square tubular shape, and a second peripheral wall 15b. It has through holes (not shown) located at the four corners of the. Further, the second case member 15 has a connector through hole 15e that penetrates a part of the second peripheral wall 15b.

The current measuring device 20 is attached to the first case member 14 by screwing the board mounting screw 17 penetrating the circuit board 31 of the current measuring device 20 into the board mounting boss 14c, and the through hole of the second case member 15 is formed. The first case member 14 and the second case member 15 are assembled by screwing the case fixing screw 16 inserted into the case mounting boss 14d. The case 13 is configured by integrally assembling the first case member 14 and the second case member 15, and the current measuring device 20 is housed in the case 13.

The case 13 is attached to the pack case 11 in a state where the outer surface of the bottom plate 14a of the first case member 14 is in contact with the attachment surface 11a of the pack case 11. Therefore, the case 13 is attached to the pack case 11 in a state where the assembling direction of the first case member 14 and the second case member 15 coincides with the longitudinal direction of the pack case 11.

As shown in FIG. 4, the current measuring device 20 housed in the case 13 includes a shunt resistor 21, a circuit board 31, and two connecting members 41 for connecting the shunt resistor 21 and the circuit board 31. Have. Further, the current measuring device 20 has elasticity located between the substrate rivet 44 and the resistance rivet 45 for fastening each connecting member 41 to the shunt resistor 21 and the circuit board 31, and the shunt resistor 21 and the connecting member 41. It has a member 48 and.

The shunt resistor 21 has, for example, a resistor 22 made of a resistance alloy such as Cu-Mn-Ni and a pair of electrode terminals 23 made of a metal such as Cu. The resistor 22 has a rectangular flat plate shape. Each electrode terminal 23 has a rectangular flat plate shape. The shunt resistor 21 is configured by arranging one electrode terminal 23, a resistor 22, and the other electrode terminal 23 in a line along the length of the electrode terminal 23. The longitudinal direction of the electrode terminal 23 is the direction in which the longitudinal direction of the two side surfaces having the largest area extends from the six side surfaces of the electrode terminal 23, and the lateral direction of the electrode terminal 23 is the direction in which the two side surfaces having the largest area extend. This is the direction in which the short side extends.

As shown in FIG. 2 or 3, in the shunt resistor 21, the direction in which one electrode terminal 23, the resistor 22, and the other electrode terminal 23 are lined up in a row is defined as the parallel arrangement direction X. The parallel direction X of the shunt resistor 21 coincides with the longitudinal direction of the electrode terminal 23. Further, the lateral direction of each electrode terminal 23 is defined as the width direction W of the shunt resistor 21. Further, the direction connecting the two side surfaces having the largest area of the electrode terminal 23 is defined as the thickness direction D1 of the shunt resistor 21. Therefore, the parallel direction X is one direction that intersects the thickness direction D1 of the resistor 22. Further, the width direction W is a direction orthogonal to the thickness direction D1 of the resistor 22 and the parallel direction X. The thickness direction D1 of the resistor 22 coincides with the thickness direction of the electrode terminal 23 and coincides with the thickness direction of the shunt resistor 21.

As shown in FIG. 3 or 4, one electrode terminal 23 is joined to the first end surface 22a of the resistor 22 in the parallel direction X, and the other electrode terminal 23 is the resistor 22 in the parallel direction X. It is joined to the second end surface 22b located on the opposite side of the first end surface 22a. The resistor 22 and each electrode terminal 23 are joined by laser welding or electron beam welding.

Each electrode terminal 23 has a through hole 23a near the resistor 22 in the parallel direction X. The through hole 23a penetrates the electrode terminal 23 in the thickness direction D1. The electrode terminal 23 includes a flat first surface 25 on one side in the thickness direction D1 and a flat second surface 26 on the other side in the thickness direction D1. The first surface 25 is one of the two side surfaces having the largest area among the six side surfaces of the electrode terminal 23, and the second surface 26 is the other side. Further, each electrode terminal 23 has a connecting hole 23b near the end on the side opposite to the through hole 23a in the parallel direction X. The connecting hole 23b penetrates the electrode terminal 23 in the thickness direction D1.

A connection bolt (not shown) penetrating a bus bar (not shown) penetrates through the connecting hole 23b of each electrode terminal 23, and a connecting nut (not shown) is screwed into the connecting bolt penetrating the electrode terminal 23. .. A bus bar is fastened to each electrode terminal 23 by screwing the connection bolt and the connection nut, and the bus bar is electrically connected to each electrode terminal 23. The bus bar electrically connected to each electrode terminal 23 is connected to a current path connecting the battery pack 10 and the load. Therefore, it can be said that the bus bar forms a part of the current path connecting the battery pack 10 and the load.

The circuit board 31 includes a main body 34 made of glass epoxy. As shown in FIG. 5, a voltage amplification IC 32 as a control unit is mounted on the first mounting surface 34a of the main body 34 in the thickness direction D2. The voltage amplification IC is mounted on the first mounting surface 34a by soldering. The voltage amplification IC 32 is an integrated circuit for converting the current flowing in the current path from the battery pack 10 to the load into a measurable voltage. The voltage amplification IC 32 constitutes an electronic component mounted on the first mounting surface 34a of the circuit board 31.

As shown in FIG. 3 or 5, a wiring pattern P for current detection is provided on the second mounting surface 34b in the thickness direction D2 of the main body 34, and the electrolytic capacitor 35 and other electronic components 36 are provided. It is mounted by soldering. Further, as shown in FIG. 2, a connector 37 for connection is mounted on the second mounting surface 34b. Holes 33 are provided at the four corners of the main body 34. The above-mentioned board mounting screw 17 is inserted into each hole 33.

As shown in FIG. 3 or 5, the two connecting members 41 are each made of L-shaped metal. In this embodiment, the connecting member 41 is made of copper. Each connecting member 41 includes a substrate-side connecting portion 42 to be fastened to the wiring pattern P of the circuit board 31, and a resistance-side connecting portion 43 to be fastened to the electrode terminal 23 of the shunt resistor 21. The substrate-side connecting portion 42 and the resistance-side connecting portion 43 are each rectangular and flat plate-shaped. Of the five side surfaces of the substrate-side connecting portion 42, one of the two surfaces having the largest area is the outer surface 42a, and the other is the inner surface 42b. Further, of the five side surfaces of the resistance side connecting portion 43, one of the two surfaces having the largest area is designated as the outer surface 43a, and the other surface is designated as the inner surface 43b.

The outer surface 42a of the board-side connecting portion 42 and the outer surface 43a of the resistance-side connecting portion 43 are orthogonal to each other, and the inner surface 42b of the substrate-side connecting portion 42 and the inner surface 43b of the resistance-side connecting portion 43 are orthogonal to each other. Therefore, the substrate side connection portion 42 and the resistance side connection portion 43 are orthogonal to each other. When the connecting member 41 is viewed from the outside in the parallel direction X, the connecting member 41 is L-shaped.

Each connecting member 41 has a first crossing line N1 at a position where the outer surface 42a of the substrate-side connecting portion 42 and the outer surface 43a of the resistance-side connecting portion 43 intersect. The first crossing line N1 is located on the outer surface side corner of the connecting member 41. Further, each connecting member 41 has a second crossing line N2 at a position where the inner surface 42b of the substrate side connecting portion 42 and the inner surface 43b of the resistance side connecting portion 43 intersect. The second crossing line N2 is located on the inner surface side corner of the connecting member 41. The first crossing line N1 is a straight line extending in the lateral direction of the outer surfaces 42a and 43a, and the second crossing line N2 is a straight line extending in the lateral direction of the inner surfaces 42b and 43b.

As shown in FIG. 4 or 5, the substrate side connection portion 42 is fastened to the wiring pattern P of the circuit board 31 by the substrate rivet 44, and the resistance side connection portion 43 is fastened to the wiring pattern P of the circuit board 31 by the resistance rivet 45 via the elastic member 48. It is fastened to the electrode terminal 23 of the shunt resistor 21. In each connecting member 41, the outer surface 42a of the board-side connecting portion 42 is in contact with the wiring pattern P provided on the second mounting surface 34b of the circuit board 31. Further, the outer surface 43a of the resistance side connecting portion 43 is in contact with the second surface 26 of each electrode terminal 23 via the elastic member 48.

In the circuit board 31, the edge of the main body 34 closest to the shunt resistor 21 is referred to as the resistor side edge 31a. In the present embodiment, the resistance side edge 31a extends linearly. The two connecting members 41 are connected to the second mounting surface 34b of the circuit board 31, but the circuit board is located so that the first crossing line N1 is located outside the shunt resistor 21 with respect to the resistance side edge 31a. It is far from 31. More specifically, when the shunt resistor 21 is viewed from the outside in the parallel direction X, each connecting member 41 is arranged so that the outer surface 43a of the resistance side connecting portion 43 is separated from the resistance side edge 31a. Is fastened to the circuit board 31. Therefore, in the side view, the shunt resistor 21 fastened to the resistance side connection portion 43 is separated from the circuit board 31. Therefore, as shown in FIG. 4, the shunt resistor 21 does not overlap the circuit board 31 when the current measuring device 20 is viewed from the outside in the width direction W of the shunt resistor 21.

Further, as shown in FIG. 5, in the current measuring device 20, the extension surfaces M1 of the first surface 25 and the second surface 26, which are both sides of the electrode terminal 23 in the thickness direction D1, and the first mounting surface of the circuit board 31. The extension surface M2 of 34a and the second mounting surface 34b intersect with each other and are orthogonal to each other in the present embodiment. That is, in the side view of the shunt resistor 21 seen along the parallel direction X and the plan view seen from the first surface 25 side, the shunt resistor 21 is the width direction W from the second mounting surface 34b of the circuit board 31. It is erected from the circuit board 31 so as to project from the circuit board 31. Therefore, in the side view, the current measuring device 20 is L-shaped.

In a side view, the protrusion dimension of the electrolytic capacitor 35 and the electronic component 36 mounted on the second mounting surface 34b from the second mounting surface 34b is the first of the voltage amplification IC 32 which is an electronic component mounted on the first mounting surface 34a. 1 It is larger than the protrusion dimension from the mounting surface 34a. Further, the protruding dimension of the electrolytic capacitor 35 and the electronic component 36 mounted on the second mounting surface 34b from the second mounting surface 34b is smaller than the protruding dimension of the shunt resistor 21 from the second mounting surface 34b. Therefore, when the current measuring device 20 is viewed from the first surface 25 side of the shunt resistor 21, the electrolytic capacitor 35 and the electronic component 36 mounted on the second mounting surface 34b protrude from the shunt resistor 21. Not.

Further, as shown in FIG. 4, the substrate-side connecting portion 42 of each connecting member 41 has a substrate-side end surface 42c at a position farthest from the shunt resistor 21 along the second mounting surface 34b. The substrate-side end surface 42c is a surface orthogonal to the outer surface 42a and the inner surface 42b and having the smallest area among the five side surfaces of the substrate-side connecting portion 42. Then, in the current measuring device 20, the electronic component 36 is mounted on the second mounting surface 34b of the circuit board 31 at a position closer to the shunt resistor 21 than the substrate side end surface 42c along the second mounting surface 34b. There is. That is, the electronic component 36 is mounted on the second mounting surface 34b at a position close to the shunt resistor 21.

In the current measuring device 20, the substrate-side connecting portion 42 and the circuit board 31 are sandwiched by the substrate rivet 44 in a state of overlapping each other. Due to the sandwiching by the board rivet 44, the board side connection portion 42 and the wiring pattern P are in close contact with each other. Due to this close contact, the wiring pattern P and the connecting member 41 are electrically connected.

As shown in FIG. 6, in the shunt resistor 21, of the pair of edge edges located at both end edges in the width direction W and extending in the parallel direction X, the edge close to the circuit board 31 is the substrate side edge 21a. And. The shunt resistor 21 is arranged on the outer surface 43a of the resistance side connection portion 43 of the connection member 41, but the substrate side edge 21a is on the resistance side of the second crossing line N2 in the longitudinal direction of the resistance side connection portion 43. It is arranged so as to be located near the tip of the connecting portion 43. More specifically, when the shunt resistor 21 is viewed from the first surface 25 side in a plan view, the shunt resistor 21 has a substrate side end edge 21a rather than an inner surface 42b of the substrate side connection portion 42. It is arranged so as to be located near the tip of 43. Therefore, the shunt resistor 21 does not overlap the circuit board 31 in a plan view when the shunt resistor 21 is viewed from the first surface 25 side which is the outside. Further, in a plan view, the shunt resistor 21 is separated from the second mounting surface 34b of the circuit board 31.

As shown in FIG. 5, the resistance rivet 45 sandwiches the resistance side connection portion 43, the elastic member 48, and the electrode terminal 23. Due to the sandwiching by the resistance rivet 45, the electrode terminal 23 and the elastic member 48 are in close contact with each other, and the resistance side connecting portion 43 and the elastic member 48 are in close contact with each other. The elastic member 48 is arranged between the second surface 26 of the electrode terminal 23 and the outer surface 43a of the resistance side connecting portion 43, and is sandwiched between the double-sided surfaces 26 and 43a in the polymerization direction. Therefore, the elastic member 48 is provided in the current measuring device 20 so that the thickness direction of the elastic member 48 coincides with the polymerization direction. Further, each elastic member 48 is compressed in the polymerization direction by caulking with the resistance rivet 45.

The elastic member 48 is formed in a ring shape by, for example, a silicon sheet. The heat resistant temperature of the elastic member 48 is preferably set to 150 to 170 degrees in order to withstand heat generation when a current is flowing through the shunt resistor 21. Further, the elastic member 48 is preferably set to have a higher thermal resistance than the electrode terminal 23 in order to make it difficult to transfer the heat generated in the shunt resistor 21 to the circuit board 31.

In the current measuring device 20, each resistance rivet 45 is electrically connected to the first surface 25 of the electrode terminal 23 and also electrically connected to the inner surface 43b of the resistance side connection portion 43. Therefore, each electrode terminal 23 is electrically connected to the connecting member 41 via the resistance rivet 45. The board-side connecting portion 42 of the connecting member 41 is electrically connected to the wiring pattern P of the circuit board 31, and the wiring pattern P is electrically connected to the voltage amplification IC. As a result, the voltage amplification IC 32 amplifies the voltage of the pair of electrode terminals 23 of the resistor 22 to a voltage that can be measured by a microcomputer (not shown), and the microcomputer measures the current flowing through the current path based on the amplified voltage. ..

Next, the operation of the current measuring device 20 will be described.
The current flowing in the current path from the battery pack 10 to the load flows from one electrode terminal 23 to the resistor 22 and flows to the other electrode terminal 23. The voltage generated by the current flowing through the resistor 22 is input to the voltage amplification IC 32 via the resistor rivet 45, the connecting member 41, and the wiring pattern P. The voltage amplification IC 32 amplifies the input voltage, and a microcomputer (not shown) measures the current value based on the amplified voltage value.

When a current flows through the shunt resistor 21, the shunt resistor 21 generates heat. The heat generated by the shunt resistor 21 is released from both the first surface 25 and the second surface 26 of the electrode terminal 23 of the shunt resistor 21 and the thickness direction D1 of the resistor 22, as well as the width direction W and the width direction W. It is emitted from both end faces in the parallel direction X. Since the circuit board 31 does not exist at the heat discharge destination, the heat generated from the shunt resistor 21 is unlikely to reach the circuit board 31.

According to the above embodiment, the following effects can be obtained.
(1) Since the heat generated by the shunt resistor 21 does not easily reach the circuit board 31, the heat does not easily reach the electrolytic capacitor 35 and the electronic component 36 mounted on the circuit board 31, and the heat does not easily reach the electrolytic capacitor 35 and the electronic component 36. It is possible to suppress the thermal influence of the above, and also to suppress the thermal influence on the solder for mounting the electrolytic capacitor 35 and the electronic component 36.

(2) The side view of the current measuring device 20 is L-shaped. Therefore, in the shunt resistor 21, the end surface in the thickness direction D1 having a large amount of heat radiation does not face the second mounting surface 34b of the circuit board 31. Therefore, the heat generated by the shunt resistor 21 can be prevented from reaching the second mounting surface 34b.

(3) Since the shunt resistor 21 does not overlap the circuit board 31 in either the plan view or the front view, it is mounted on the second mounting surface 34b at a position closer to the shunt resistor 21 than the substrate side end surface 42c. Even with the electronic component 36, the influence of heat generated by the shunt resistor 21 can be reduced.

(4) The shunt resistor 21 and the circuit board 31 are connected by two connecting members 41, and the current measuring device 20 is formed in an L shape. Then, by adjusting the arrangement of the shunt resistor 21 and the circuit board 31 with respect to the connecting member 41, it is possible to secure the creepage distance and the space distance regarding the electrical insulation of the shunt resistor 21 and the circuit board 31.

(5) The shunt resistor 21 and the circuit board 31 are connected by an L-shaped connecting member 41. For example, the connection member 41 is compared with the case where the end surface of the shunt resistor 21 in the thickness direction D1 and the second mounting surface 34b of the circuit board 31 are opposed to each other and the electrode terminal 23 and the wiring pattern P are solder-connected. Can have a larger surface area than solder. Therefore, as compared with the case where the shunt resistor 21 and the circuit board 31 are solder-connected, the amount of heat radiated from the connecting member 41 can be increased, and the heat generated by the shunt resistor 21 is less likely to reach the circuit board 31.

(6) The connecting member 41 and the shunt resistor 21 are mechanically fastened by the resistance rivet 45, and the connecting member 41 and the circuit board 31 are mechanically fastened by the board rivet 44. Therefore, it is possible to eliminate cracks in the solder due to the influence of heat as in the case where the shunt resistor 21 and the circuit board 31 are solder-connected.

(7) As a method of integrating the shunt resistor 21 and the circuit board 31, for example, a method of bending a part of the circuit board 31 to form a bent portion and joining the bent portion and the shunt resistor 21. By adopting it, the shunt resistor 21 and the circuit board 31 can be integrated without overlapping in front view and plan view. However, this method is not preferable because the heat generated from the shunt resistor 21 is directly transferred to the circuit board 31. When the shunt resistor 21 and the circuit board 31 are integrally connected via the connecting member 41, the heat generated by the shunt resistor 21 is transferred to the circuit board 31 via the connecting member 41, but the circuit board 31 Since the connection member 41 is separate from the circuit board, heat transfer to the circuit board 31 can be suppressed.

(8) The protruding dimensions of the electrolytic capacitor 35 and the electronic component 36 mounted on the second mounting surface 34b from the second mounting surface 34b are the first of the voltage amplification IC 32 and the electronic component 36 mounted on the first mounting surface 34a. It is larger than the protrusion dimension from the mounting surface 34a and smaller than the protrusion dimension from the second mounting surface 34b of the shunt resistor 21. Therefore, as long as it is within the dimension W in the width direction of the shunt resistor 21, the current measuring device 20 does not become large even if the protruding dimensions of the electrolytic capacitor 35 and the electronic component 36 are large. Further, the current measurement is performed by making the protruding dimensions of the voltage amplification IC 32 and the electronic component 36 mounted on the first mounting surface 34a smaller than the protruding dimensions of the electrolytic capacitor 35 and the electronic component 36 mounted on the second mounting surface 34b. The device 20 does not need to be large.

(9) The electrode terminal 23 and the resistance side connection portion 43 are fastened by a resistance rivet 45, and an elastic member 48 is interposed between the electrode terminal 23 and the resistance side connection portion 43. When a current flows through the shunt resistor 21, when the electrode terminal 23 generates heat and thermally expands, the electrode terminal 23 is fastened to the resistance side connection portion 43 in the overlapping direction by the resistance rivet 45. Is thermally expanded in the polymerization direction, but the thermal expansion of the electrode terminal 23 is absorbed by elastically deforming the elastic member 48 in the polymerization direction so that the thickness of the elastic member 48 becomes thin. Further, since the thermal resistance of the elastic member 48 suppresses the heat conduction from the electrode terminal 23 to the connecting member 41, the heat conduction to the circuit board 31 can be suppressed.

(10) The current measuring device 20 is formed in an L shape in a side view, and the circuit board 31 does not face the second surface 26 of the shunt resistor 21 and is open. Therefore, it is easy to fasten the electrode terminal 23 and the bus bar.

(11) The shunt resistor 21 is arranged on the outer surface 43a of the resistance side connection portion 43, and the circuit board 31 is arranged on the outer surface 42a of the substrate side connection portion 42. Therefore, in a configuration in which the shunt resistor 21 and the circuit board 31 are integrated by the connecting member 41, as compared with the case where the shunt resistor 21 and the circuit board 31 are arranged on the inner surfaces 42b and 43b of the connecting member 41, for example, as compared with the case where the shunt resistor 21 and the circuit board 31 are arranged on the inner surfaces 42b and 43b of the connecting member 41. The shunt resistor 21 and the circuit board 31 can be separated from each other.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
○ In the embodiment, the method of fastening the electrode terminal 23 of the shunt resistor 21 and the connecting member 41 may be performed by using bolts and nuts instead of the resistance rivet 45, or the circuit board 31 and the connecting member 41 may be fastened to each other. The method of fastening may be performed with bolts and nuts instead of the substrate rivet 44.

○ It is not necessary to interpose the elastic member 48 between the electrode terminal 23 of the shunt resistor 21 and the resistance side connecting portion 43.
○ In at least one of the electrolytic capacitor 35 and the electronic component 36 mounted on the second mounting surface 34b, the protruding dimension from the second mounting surface 34b is larger than the protruding dimension of the shunt resistor 21 from the second mounting surface 34b. You may. In this case, in at least one of the electrolytic capacitor 35 and the electronic component 36, the protruding dimension from the second mounting surface 34b may be smaller than the protruding dimension of the voltage amplification IC 32 and the electronic component 36 from the first mounting surface 34a. , May be large.

○ On the second mounting surface 34b, the electronic component 36 may not be mounted at a position closer to the shunt resistor 21 than the substrate side end surface 42c.
○ As long as the shunt resistor 21 and the circuit board 31 do not overlap in the plan view and the front view, the shunt resistor 21 may be arranged on either the outer surface 43a or the inner surface 43b of the resistance side connection portion 43, and the circuit. The substrate 31 may also be arranged on either the outer surface 42a or the inner surface 42b of the substrate side connection portion 42.

○ If the shunt resistor 21 and the circuit board 31 do not overlap in the plan view and the front view, the board-side connecting portion 42 of the connecting member 41 straddles the first mounting surface 34a and the second mounting surface 34b of the circuit board 31. It may be attached to the main body 34 in a slanted state.

The shunt resistor 21 may be integrated with the circuit board 31 in a state where the parallel direction X of the shunt resistor 21 projects from the second mounting surface 34b. That is, the shunt resistor 21 may be integrated with the circuit board 31 in a state where the length of each electrode terminal 23 extends from the second mounting surface 34b of the circuit board 31.

○ Even if the board-side connection portion 42 of the connection member 41 and the circuit board 31 are electrically connected by solder, and the resistance-side connection portion 43 of the connection member 41 and the shunt resistor 21 are electrically connected by solder. Good.

○ In the current measuring device 20, the extension surfaces M1 of the first surface 25 and the second surface 26, which are both sides of the resistor 22 in the thickness direction D1, and the first mounting surface 34a and the second mounting surface 34b of the circuit board 31. It does not have to be orthogonal as long as it intersects with the extension surface M2.

○ The shunt resistor 21 and the circuit board 31 do not have to be integrated. For example, the shunt resistor 21 may be supported by the second peripheral wall 15b of the second case member 15, and the circuit board 31 may be supported by the bottom plate 14a of the first case member 14.

○ The current measuring device 20 may be provided in the battery instead of the battery pack 10 having a plurality of secondary batteries 12.

D1, D2 ... Thickness direction, M1, M2 ... Extension surface, P ... Wiring pattern as a conductive part, X ... Parallel direction, W ... Width direction, 20 ... Current measuring device, 21 ... Shunt resistor, 22 ... Resistance Body, 23 ... electrode terminal, 31 ... circuit board, 32 ... control unit and voltage amplification IC as electronic component, 34a ... first mounting surface, 34b ... second mounting surface, 35 ... electrolytic capacitor as electronic component, 36 ... Electronic component, 41 ... Connection member, 42 ... Board side connection part, 42c ... Board side end face, 43 ... Resistance side connection part, 48 ... Elastic member.

Claims (5)

A current measuring device installed in the current path.
A shunt resistor having a flat plate-shaped resistor and a pair of electrode terminals sandwiching the resistor along a parallel direction, which is one direction intersecting the thickness direction of the resistor.
It has a circuit board in which a control unit for measuring the voltage of the pair of electrode terminals of the resistor is arranged on a mounting surface, and also has.
The shunt resistor and the circuit board are integrated in a state where both sides of the resistor in the thickness direction and the extension surfaces of the mounting surface of the circuit board intersect with each other.
In the shunt resistor, the width direction is defined as the direction orthogonal to the thickness direction and the juxtaposition direction of the resistor.
When the shunt resistor and the circuit board are viewed from the outside in the width direction, the shunt resistor and the circuit board do not overlap with each other.
Moreover, the current measuring device is characterized in that the shunt resistor and the circuit board do not overlap in a plan view of the shunt resistor and the circuit board from the outside in the thickness direction. A metal connecting member is connected to the electrode terminal of the shunt resistor and the conductive portion of the control unit on the circuit board, and the connecting member is a flat plate-shaped resistance-side connecting portion to be fastened to the electrode terminal. And a flat plate-shaped substrate-side connecting portion to be fastened to the conductive portion, and the side view of the connecting member viewed from the outside in the parallel arrangement direction is L-shaped, and the shunt resistor is formed by the connecting member. The current measuring device according to claim 1, wherein the circuit board and the circuit board are integrated. The circuit board includes the mounting surface on which the control unit is arranged as a first mounting surface on one surface in the thickness direction, and the substrate-side connecting portion of the connecting member is arranged on the other surface in the thickness direction. With a second mounting surface
The substrate-side connection portion has a substrate-side end surface at a position farthest from the shunt resistor along the second mounting surface.
The current measuring device according to claim 2, wherein the electronic component is mounted at a position closer to the shunt resistor than the substrate side end surface along the second mounting surface. In the plan view, the shunt resistor projects from the second mounting surface in the width direction, and the protrusion dimension of the electronic component mounted on the second mounting surface from the second mounting surface is the first mounting surface. The current measuring device according to claim 3, wherein the electronic component mounted on the shunt resistor is larger than the protrusion dimension from the first mounting surface and smaller than the protrusion dimension from the second mounting surface of the shunt resistor. The electrode terminal and the connecting member are fastened in the polymerization direction, an elastic member is interposed between the electrode terminal and the connecting member in the polymerization direction, and the elastic member has a thermal resistance as compared with the electrode terminal. The current measuring device according to any one of claims 2 to 4.

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