Battery monitoring unit

A battery monitoring unit includes a plurality of voltage detection lines, a flexible printed circuit board extending in a stuck direction of single batteries, an electronic circuit connected to one end portions of the plurality of the voltage detection lines so as to detect voltage of each of the single batteries and mounted on the flexible printed circuit board, a plurality of busbar fixing portions formed integrally with the flexible printed circuit board and to which the plurality of the busbars are fixed respectively, and communication lines disposed in the flexible printed circuit board so as to connect between the electronic circuit and a battery ECU.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2016-187522 filed on Sep. 26, 2016, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a battery monitoring unit.

Description of Related Art

A power storage device which is a battery assembly is constituted by a plurality of single batteries (battery cells) which are connected to one another side by side. In a power storage device501shown inFIG. 8A, electrode terminals507of adjacent battery cells505are connected by busbars503, and the busbars503are coupled by voltage detection lines509such as FFCs (Flexible Flat Cables). The voltage detection lines509are respectively led out of opposite sides of the electrode terminals507of the battery cells505arranged in parallel, and connected to a battery ECU511having a battery cell voltage detection circuit (electronic circuit) provided in another box. For this reason, the voltage detection lines509require long wirings.

As a solution to this problem, it has been proposed that a voltage detection circuit of a battery monitoring unit is housed in a battery pack as in Patent Literatures 1 and 2. For example, a battery pack disclosed in Patent Literature 1 includes a circuit board, a circuit board fixation member, busbar retention members, and a wiring portion. The circuit board detects voltage of each of battery cells. The circuit board fixation member has a board housing portion to which the circuit board is attached. The circuit board fixation member extends in a stuck direction of the battery cells. The busbar retention members are formed integrally with the circuit board fixation member so as to house busbars disposed side by side in the stuck direction so as to connect electrode terminals of the battery cells. The wiring portion is placed on the circuit board fixation member. The wiring portion includes the plurality of busbars, and a flexible wiring portion or a wiring central portion which is connected between the busbars and the circuit board.

According to such a battery pack, the circuit board having the voltage detection circuit can be housed in the battery pack.[Patent Literature 1] JP-A-2015-22965[Patent Literature 2] JP-A-2015-49931

According to a related art, in a battery monitoring unit, a circuit board, a wiring portion and busbars have to be disposed respectively and fixed integrally on the circuit board fixation member in which the board housing portion housing the circuit board and the busbar retention members housing the busbars are formed integrally. Therefore, assembling work for the battery monitoring unit becomes so complex that there is a problem that manufacturing cost may increase.

SUMMARY

One or more embodiments provide a battery monitoring unit which is in a simple structure so that complex assembling work can be reduced.

In an aspect (1), a battery monitoring unit includes a plurality of voltage detection lines, a flexible printed circuit board extending in a stuck direction of single batteries, an electronic circuit connected to one end portions of the plurality of the voltage detection lines so as to detect voltage of each of the single batteries and mounted on the flexible printed circuit board, a plurality of busbar fixing portions formed integrally with the flexible printed circuit board and to which the plurality of the busbars are fixed respectively, and communication lines disposed in the flexible printed circuit board so as to connect between the electronic circuit and a battery ECU. The other end portions of the plurality of the voltage detection lines are respectively connected to the plurality of the busbars disposed in the stuck direction so as to electrically connect the plurality of the single batteries of a battery assembly. The plurality of the voltage detection lines are disposed in the flexible printed circuit board.

According to the aspect (1), the voltage detection lines, the busbar fixing portions and the communication lines are formed integrally as the flexible printed circuit board. The voltage detection lines are connected to the busbars by which the single batteries are electrically connected to one another. The busbars are fixed to the busbar fixing portions. The communication lines are provided for making connection between the electronic circuit and the battery ECU. The electronic circuit for detecting voltage of each of the single batteries is directly mounted on the flexible printed circuit board. In this manner, the battery monitoring unit is configured. Therefore, the battery monitoring unit has the aforementioned configuration in which constituent components of the electronic circuit such as a chip fuse and cell monitoring ICs can be surface-mounted on the flexible printed circuit board so as to be formed integrally therewith. In the flexible printed circuit board, the voltage detection lines and the communication lines are, for example, formed as a circuit on abase film by printing. Thus, assembling work for the battery monitoring unit can be easier than that for the background-art battery monitoring unit.

In an aspect (2), the plurality of the busbar fixing portions include flexible bridge portions between adjacent ones of a plurality of opening portions opening at predetermined interval in a row in the stuck direction. Each of the plurality of the opening portions has an opening width wider than a transverse-direction width of each of the plurality of the busbars, in a direction which is perpendicular to the stuck direction and a thickness direction of each of the plurality of the busbars.

According to the aspect (2), the flexible bridge portions of the busbar fixing portions to which the busbars are fixed have flexibility. Therefore, when the battery monitoring unit is attached to the power storage device, the flexible bridge portions can be slanted or bent so that the busbars can be displaced following electrodes of the single batteries. Accordingly, individual differences of the cells and pitch tolerances or height differences of the electrodes caused by expansion etc. among the single batteries can be also absorbed.

In an aspect (3), the plurality of the busbars are soldered and fixed to lands positioned and extending on the flexible bridge portions from the other end portions of the plurality of the voltage detection lines respectively.

According to the aspect (3), the busbars can be soldered to the lands of the flexible bridge portions simultaneously when the constituent components of the electronic circuit are surface-mounted on the flexible printed circuit board. Therefore, electric connection of the busbars to the voltage detection lines and fixation of the busbars to the flexible bridge portions can be performed simultaneously. Thus, assembling work for the battery monitoring unit can be further easier.

In an aspect (4), a gas discharging duct extending in the stuck direction so as to discharge gas generated inside the single batteries to the outside is disposed on upper surfaces of the single batteries. A portion of the flexible printed circuit board, on which the electronic circuit is mounted, is disposed to be contact with an upper surface of the gas discharging duct.

According to the aspect (4), gas generated inside the single batteries can be discharged to the outside by the gas discharging duct. In addition, the portion of the flexible printed circuit board where the electronic circuit is mounted is disposed to make contact with the upper surface of the gas discharging duct. Accordingly, the electronic circuit mounted on the flexible printed circuit board can be supported surely.

Advantageous Effects of Invention

According to the battery monitoring unit according to the invention, it is possible to reduce complex assembling work using a simple structure.

The invention has been described above briefly. Further, when modes (hereinafter referred to as “embodiments”) for carrying out the invention which will be described below are read through with reference to the accompanying drawings, details of the invention can be made clearer.

DETAILED DESCRIPTION

Exemplary embodiments are described below with reference to the drawings.

FIG. 1is an exploded perspective view schematically showing the configuration of a power storage device100provided with a battery monitoring unit110according to a first embodiment of the invention.FIG. 2is a perspective view of the battery monitoring unit110shown inFIG. 1.FIG. 3Ais a perspective view of an enlarged portion A of the battery monitoring unit110inFIG. 2.FIG. 3Bis an exploded perspective view of busbars13inFIG. 3A. Incidentally, in the embodiment, up/down, front/rear and left/right directions will follow directions of arrows shown inFIG. 1.

The power storage device100provided with the battery monitoring unit110according to the first embodiment can be mounted in a vehicle and used as a power source for driving the vehicle. That is, electric energy outputted from the power storage device100can be converted into kinetic energy by a motor generator to drive the vehicle. In addition, when kinetic energy generated during braking of the vehicle is converted into electric energy by the motor generator, the power storage device100can store the electric energy as regenerative electric power.

As shown inFIG. 1, the power storage device100is a battery assembly47having a plurality of single batteries11which are stucked and disposed in the front/rear direction. For example, the plurality of single batteries11are housed in a box-shaped case or bound with a binding band to be fixed integrally. A rechargeable battery such as a nickel-metal hydride battery or a lithium-ion battery can be used as each of the single batteries11. Here, the plurality of single batteries11are electrically connected in series. That is, the busbars13are disposed on upper surfaces of the single batteries11. Two single batteries11which are adjacent to each other in the front/rear direction are electrically connected in series by each of the busbars13.

Each of the single batteries11is provided with a rectangular parallelepiped battery body21, and a pair of a positive electrode terminal15and a negative electrode terminal17. The positive electrode terminal15and the negative electrode terminal17are electrodes protruding respectively from one end and the other end of an upper surface23of the battery body21. The positive electrode terminal15is electrically connected to a positive electrode plate (current collector plate) of a power generation element inside the battery body21. The negative electrode terminal17is electrically connected to a negative electrode plate (current collector plate) of the power generation element inside the battery body21. In addition, a valve25is provided in the upper surface23of the battery body21. The valve25is provided between the positive electrode terminal15and the negative electrode terminal17in the left/right direction. The valve25is used for releasing gas generated inside the battery body21to the outside of the battery body21.

When, for example, overcharging etc. of the single battery11is performed, there is a fear that gas may be generated mainly from an electrolyte solution. Since the battery body21is in a sealed state, internal pressure of the battery body21increases as the gas is generated. As soon as the internal pressure of the battery body21reaches operating pressure of the valve25, the valve25can change from a closed state to an open state to thereby release the gas to the outside of the battery body21.

A so-called break type valve or a so-called return type valve can be used as the valve25. As the break type valve, the valve25changes from the closed state to the open state irreversibly. The break type valve can be formed, for example, by engraving the upper surface23of the battery body21. On the other hand, as the return type valve, the valve25changes between the closed state and the open state reversibly in accordance with the internal pressure of the battery body21. The return type valve can be configured, for example, using a spring.

Each of the busbars13has a rectangular shape on the whole. A pair of terminal insertion holes14are formed in the busbar13so that the positive electrode terminals15or the negative electrode terminals17can be inserted through the pair of terminal insertion holes14so as to be connected to the busbar13(seeFIGS. 3A and 3B). The busbar13can be formed by punching a metal plate material made of copper, a copper alloy, aluminum, an aluminum alloy, gold, stainless steel (SUS), or the like. in a press step. So as to improve weldability, plating treatment with Sn, Ni, Ag, Au, or the like, may be applied to the busbar13.

The busbars13are disposed so that the terminal insertion holes14through which the positive electrode terminals15or the negative electrode terminals17are inserted so as to be connected to the busbars13can be arranged in a row.

Incidentally, when nuts43are screwed and fastened to the positive electrode terminals15and the negative electrode terminals17which have been inserted through the terminal insertion holes14, the busbars13according to the embodiment are electrically connected to the positive electrode terminals15and the negative electrode terminals17. It is a matter of course that the busbars according to the invention may be electrically connected to the positive electrode terminals and the negative electrode terminals by laser welding without forming the terminal insertion holes14.

In addition, each of the busbars13according to the first embodiment has notches16formed at its opposite edge portions between the pair of terminal insertion holes14. When the busbar13is soldered to a land30, excellent solder fillets can be formed between the notches16and the land30. The land30is provided to extend on a flexible bridge portion32which will be described later.

As shown inFIG. 1, a U-shaped flexible printed circuit board27is disposed in the stuck direction of the single batteries11on the plurality of single batteries11. The flexible printed circuit board27has belt-like wiring portions26and28and a connection wiring portion24. The belt-like wiring portions26and28are disposed in two rows in the stuck direction of the single batteries11. The connection wiring portion24connects one end sides of the belt-like wiring portions26and28.

The belt-like wiring portions26and28are disposed in two rows on the positive electrode terminals15and the negative electrode terminals17respectively. The plurality of busbars13are arranged alternately in the stuck direction of the single batteries11on the positive electrode terminals15and the negative electrode terminals17. The connection wiring portion24is disposed on ones of the valves25of the plurality of single batteries11on a front side.

As shown inFIG. 2, the battery monitoring unit110of the power storage device100according to the first embodiment is provided with a plurality of voltage detection lines29, the flexible printed circuit board27, an electronic circuit48, the flexible bridge portions32, and communication lines31. The voltage detection lines29have one end portions connected to the busbars13respectively. The flexible printed circuit board27in which the plurality of voltage detection lines29are disposed extends in the stuck direction of the single batteries11. The electronic circuit48is connected to the other end portions of the voltage detection lines29so as to detect voltage of each of the single batteries11. The flexible bridge portions32serve as busbar fixing portions formed integrally with the flexible printed circuit board27. The communication lines31are provided for making connection between the electronic circuit48and a battery ECU20.

The voltage detection lines29and the communication lines31disposed in the flexible printed circuit board27are formed in the following manner. That is, leadframes (metal thin plates)61and63including a large number of thin copper wirings which are, for example, pattern-formed by etching are disposed on a base film60and covered with transparent cover films65and67bonded by an adhesive agent64(seeFIG. 4) so that the voltage detection lines29and the communication lines31can be formed. In addition, a flexible printed circuit board27according to a second embodiment has a two-layer structure in which voltage detection lines29are disposed on upper and lower surfaces of a base film60in each of belt-like wiring portions26and28. When the voltage detection lines29are formed in the two-layer structure in this manner, the belt-like wiring portion26,28in which the plurality of voltage detection lines29are arranged side by side at predetermined intervals (insulation distances) in a stuck direction of single batteries11can be made compact in terms of width. When the number of the stucked single batteries11is so small that a large number of the voltage detection lines29do not have to be provided, it is a matter of course that a flexible printed circuit board27having a single-layer structure of the voltage detection lines29may be used

In the electronic circuit48according to the embodiment, components such as a chip fuse39, a resistor51, a capacitor53and cell monitoring ICs49are electrically connected by the leadframes61and63or through holes6and mounted on the connection wiring portion24. For example, as shown inFIG. 4, each of the monitoring ICs49is surface-mounted on the flexible printed circuit board27in the following manner. That is, solders70are applied or printed on predetermined positions of the flexible printed circuit board27where the leadframes61and63have been pattern-formed into predetermined shapes simultaneously with the voltage detection lines29and the communication lines31. Then, terminals73of the monitoring IC49are placed on the solders70to be reflow-soldered so that the monitoring IC49can be mounted on the flexible printed circuit board27.

Incidentally, the electronic circuit48mounted on the connection wiring portion24of the flexible printed circuit board27may be formed into a multilayer structure including three or more layers. When the electronic circuit48is formed into the multilayer structure, the connection wiring portion24on which the electronic circuit48for detecting voltages of the single batteries11is mounted can be made compact.

That is, the plurality of voltage detection lines29and the communication lines31are electrically connected by the leadframes61and63and the through holes6, and disposed in the flexible printed circuit board27. The leadframes61and63are pattern-formed into the predetermined shapes. The one end portions of the voltage detection lines29are connected to the busbars13respectively while the other end portions of the voltage detection lines29are connected to predetermined connection end portions of the electronic circuit48respectively. The communication lines31make connection between the electronic circuit48mounted on the connection wiring portion24and terminals of a connector22provided and disposed on a front end of the belt-like wiring portion26.

According to the first embodiment, as shown inFIG. 3B, each of the flexible bridge portions32is formed between adjacent ones of opening portions33which are opened in each belt-like wiring portion26,28in one row at predetermined intervals in the stuck direction of the single batteries11. Each opening portion33has an opening width H wider than a transverse-direction width w of each busbar13. The opening portion33are approximately rectangular openings through which the positive electrode terminals15and the negative electrode terminals17are inserted. Each flexible bridge portion32which is shaped like a long and narrow belt is formed between adjacent ones of the opening portions33. The land30provided to extend on the flexible bridge portion32from the one end portion of the corresponding voltage detection line29is formed on the upper surface of the flexible bridge portion32.

As shown inFIGS. 3A and 3B, each voltage detection line29disposed on a lower surface side of the flexible printed circuit board27has one end portion exposed on the upper surface side of the flexible printed circuit board27immediately before the flexible bridge portion32so as to be connected to the land30. Incidentally, the voltage detection line29exposed on the upper surface side of the flexible printed circuit board27in the drawings is in fact coated and covered with the not-shown cover film65to be insulated.

Therefore, each of the busbars13is soldered (e.g. reflow-soldered) to a corresponding one of the lands30of the flexible bridge portions32. Thus, the busbar13is fixed to a corresponding one of the belt-like wiring portions26and28of the flexible printed circuit board27. On this occasion, excellent solder fillets are formed between the notches16of the busbar13and the land30. Accordingly, the busbar13is electrically, mechanically and firmly connected to the land30of the flexible bridge portion32.

The transverse-direction width w of the busbar13fixed to the flexible bridge portion32is narrower than the opening width H of the opening portion33. Accordingly, even when the flexible bridge portion32is slanted or bent, the busbar13can be displaced desirably without interfering with the belt-like wiring portion26,28.

In addition, the plurality of opening portions33are opened at the predetermined intervals in one row in the stuck direction of the single batteries11in the belt-like wiring portion26,28so as to form the flexible bridge portions32. Outer side ends of the flexible bridge portions32formed thus are coupled by a coupling portion34which is continuous in the stuck direction of the single batteries11. The outer side ends of the flexible bridge portions32are respectively connected to the coupling portion34so as to suppress a variation in individual position among the busbars13fixed to the flexible bridge portions32.

Accordingly, the busbars13are not retained by busbar retention members as in the background art but only directly fixed to the flexible bridge portions32formed in the belt-like wiring portions26and28of the flexible printed circuit board27which is bent easily. In spite of this, workability for inserting the terminal insertion holes14of the busbars13onto the positive electrode terminals15and the negative electrode terminals17correspondingly can be prevented from being lowered, and bonding force between the busbars13and the flexible bridge portions32can be prevented from being lowered.

According to the first embodiment, the communication lines31are disposed in the flexible printed circuit board27to connect the electronic circuit48and the terminals of the connector22to each other respectively. The electronic circuit48is mounted on the connection wiring portion24. The terminals of the connector22are provided and disposed on the front end of the belt-like wiring portion26. Therefore, when the connector22and the battery ECU20are connected to each other by a not-shown wire harness, the communication lines31can electrically connect the electronic circuit48and the battery ECU20to each other. The communication lines31may connect connection portions of the electronic circuit48respectively to the battery ECU20so as to make communication therebetween or may connect the connection portions of electronic circuit48collectively to the battery ECU20so as to make multiplex communication therebetween.

In the power storage device100according to the first embodiment, a gas discharging duct45extending in the front/rear direction of the battery assembly47is disposed on the upper surfaces23of the plurality of single batteries11. A lower surface of the gas discharging duct45makes contact with the upper surfaces23of the single batteries11. The gas discharging duct45moves gas released from the valves25of the single batteries11in a direction away from the battery assembly47. When, for example, the power storage device100is mounted in the vehicle, the gas discharging duct45can be used to discharge the gas released from the valves25to the outside of the vehicle.

When the flexible printed circuit board27is disposed on the plurality of single batteries11, the lower surface side of the connection wiring portion24on which the electronic circuit48is mounted is disposed to make contact with an upper surface46of the gas discharging duct45.

In the flexible printed circuit board27disposed on the plurality of single batteries11, the positive electrode terminals15and the negative electrode terminals17are inserted through the terminal insertion holes14of the busbars13fixed to the flexible bridge portions32respectively. The nuts43are screwed and fastened to the positive electrode terminals15and the negative electrode terminals17which have been inserted through the terminal insertion holes14. Thus, the busbars13electrically connect the plurality of single batteries11in series.

The connection wiring portion24of the flexible printed circuit board27on which the electronic circuit48is mounted is covered with a protective cover10so that undesired contact of an external member can be prevented.

Next, effects of the aforementioned configuration will be described.

According to the battery monitoring unit110according to the first embodiment, the plurality of voltage detection lines29, the plurality of flexible bridge portions32and the communication lines31are formed integrally as the flexible printed circuit board27. The voltage detection lines29are respectively connected to the busbars13which electrically connect the single batteries11to one another. The busbars13are fixed to the flexible bridge portions32. The communication lines31are provided for making connection between the electronic circuit48and the battery ECU20. The electronic circuit48for detecting voltage of each of the single batteries11is directly mounted on the flexible printed circuit board27. Thus, the battery monitoring unit110is configured.

Therefore, in the battery monitoring unit110according to the embodiment, the constituent components of the electronic circuit48such as the chip fuse39and the cell monitoring ICs49are surface-mounted on the flexible printed circuit board27so as to be formed integrally therewith. In the flexible printed circuit board27, the voltage detection lines29and the communication lines31are, for example, formed as a circuit on the base film60by printing. Thus, assembling work for the battery monitoring unit110configured thus according to the embodiment can be easier than that for the background-art battery monitoring unit in the battery pack.

Further, in the battery monitoring unit110according to the first embodiment, the flexible bridge portions32each shaped like a long and narrow belt have flexibility. The flexible bridge portions32serve as busbar fixing portions for fixing the busbars13. Therefore, when the battery monitoring unit110is attached to the power storage device100, the flexible bridge portions32are slanted or bent so that the busbars13can be displaced following the positive electrode terminals15and the negative electrode terminals17of the single batteries11. In addition, individual differences of the cells and pitch tolerances or height differences of the positive electrode terminals15and the negative electrode terminals17caused by expansion etc. among the respective single batteries11can be also absorbed.

In addition, in the battery monitoring unit110according to the first embodiment, the busbars13are soldered and fixed to the lands30which are provided to extend on the flexible bridge portions32from the other end portions of the voltage detection lines29. Therefore, when the constituent components of the electronic circuit48are surface-mounted on the flexible printed circuit board27, the busbars13can be soldered (e.g. reflow-soldered) to the lands30of the flexible bridge portions32simultaneously. Therefore, electric connection of the busbars13to the voltage detection lines29and fixation of the busbars13to the flexible bridge portions32are performed simultaneously. Accordingly, the assembling work for the battery monitoring unit110can be made further easier.

In addition, in the battery monitoring unit110according to the first embodiment, the gas discharging duct45is disposed on the upper surfaces23of the plurality of single batteries11, and a portion (i.e. the connection wiring portion24) of the flexible printed circuit board27on which the electronic circuit48is mounted is disposed to make contact with the upper surface46of the gas discharging duct45. Therefore, the gas generated inside the single batteries11can be discharged to the outside by the gas discharging duct45. In addition, the portion of the flexible printed circuit board27on which the electronic circuit48is mounted is disposed to make contact with the upper surface of the gas discharging duct45. Thus, the electronic circuit48which is mounted on the flexible printed circuit board47can be supported surely.

Next, a battery monitoring unit according to a second embodiment of the invention will be described.

FIG. 5is a plan view of the battery monitoring unit210according to the second embodiment of the invention.FIG. 6Ais a perspective view of an enlarged portion B of the battery monitoring unit210inFIG. 5.FIG. 6Bis a sectional view taken along a line of arrows VI-VI ofFIG. 6A. In the second embodiment, constituents the same as the aforementioned constituents which have been described in the first embodiment will be referred to by the same signs correspondingly and respectively, and duplicated description thereof will be omitted.

Similarly to the configuration of the aforementioned battery monitoring unit110according to the first embodiment, the battery monitoring unit210according to the second embodiment is provided with a plurality of voltage detection lines29, a flexible printed circuit board27A, an electronic circuit48, flexible bridge portions32, and communication lines31. One end portions of the voltage detection lines29are connected to a plurality of busbars13respectively. The flexible printed circuit board27A on which the plurality of voltage detection lines29are disposed extends in a stuck direction of single batteries11. The electronic circuit48is connected to the other end portions of the voltage detection lines29so as to detect voltage of each of the single batteries11. The flexible bridge portions32are formed integrally with the flexible printed circuit board27A. The communication lines31are provided for making connection between the electronic circuit48and a battery ECU20.

In the aforementioned flexible printed circuit board27according to the first embodiment, all the voltage detection lines29are provided side by side on inner sides of the busbars13which are arrayed in parallel on the belt-like wiring portions26and28, as shown inFIG. 2. On the other hand, in the flexible printed circuit board27A according to the second embodiment, the voltage detection lines29are divided to be provided side by side on inner sides and outer sides of the busbars13which are arrayed in parallel on the belt-like wiring portions26and28, as shown inFIG. 5andFIGS. 6A and 6B.

That is, the flexible printed circuit board27and the flexible printed circuit board27A are suitably selected and used in accordance with a plurality of power storage devices100in which a protrusion interval varies between positive electrode terminals15and negative electrode terminals17which are protruded from upper surfaces23of battery bodies21so that a disposition space can vary between the inner sides and the outer sides of the busbars13. Thus, the battery monitoring unit110,210can be adapted to the power storage devices100in various forms.

FIGS. 7A and 7Bare an exploded perspective view and a perspective view of an enlarged important part of a battery monitoring unit310according to a third embodiment of the invention.

A flexible printed circuit board27B of the battery monitoring unit310according to the third embodiment has the same configuration as the aforementioned flexible printed circuit board27A according to the second embodiment except that the configuration of each of the flexible bridge portions32is changed to the configuration of each of flexible bridge portions32A.

As shown inFIG. 7A, each of the flexible bridge portions32A of the flexible printed circuit board27B according to the third embodiment is formed between adjacent ones of opening portions35which are opened respectively in one row in a stuck direction of single batteries11in each of belt-like wiring portions26and28. Each of the opening portions35is a convex opening on the whole. The flexible bridge portion32A which is shaped like a belt widened on one end side is formed between the adjacent opening portions35. A substantially Y-shaped land30A provided to extend on the flexible bridge portion32A from one end portion of a corresponding voltage detection line29is formed on an upper surface of the flexible bridge portion32A. Incidentally, a lightening hole36is formed in the widened portion of the flexible bridge portion32A so that the widened portion of the flexible bridge portion32A can be lowered in rigidity and bent easily.

On the other hand, a pair of notches16are formed at outer edge portions of each of busbars13A according to the third embodiment. Thus, the busbar13A has a total of three notches16.

The busbars13A are soldered (e.g. reflow-soldered) to the lands30A of the flexible bridge portions32A respectively. Thus, the busbars13A are fixed to the respective belt-like wiring portions26and28of the flexible printed circuit board27B. On this occasion, excellent solder fillets are formed between the three notches16of each of the busbars13A and the corresponding land30A.

Accordingly, the busbar13A according to the third embodiment can have three solder fillets on the land30A of the flexible bridge portion32A. Thus, the busbar13A can be connected to the land30A of the flexible bridge portion32A more electrically and mechanically firmly than the busbar13according to the aforementioned embodiment.

Although the various embodiments have been described above with reference to the drawings, it is a matter of course that the invention is not limited to such examples. It is obvious that those skilled in the art can arrive at various change examples or modification examples without departing from the scope described in Claims. Accordingly, it should be understood that the various change examples or modification examples surely belong to the technical scope of the invention.

For example, the aforementioned configuration examples have been descried in the case where each electrode is an electrode column by way of example. However, the electrode may be a flat plate electrode. Accordingly, connection between the busbar and the electrode is not limited to screw fastening but may be welding or the like. In addition, it is a matter of course that the connection patterns of the plurality of voltage detection lines29to the busbars13are not limited to the connection patterns in each of the aforementioned embodiments but various connection patterns which can be routed in the flexible printed circuit board27can be used.

Accordingly, according to the battery monitoring unit110,210,310according to each of the aforementioned embodiments, complex assembling work can be reduced using a simple structure, and the pitch tolerances of the positive electrode terminals15and the negative electrode terminals17among the respective single batteries11can be also absorbed.

Here, the aforementioned features of the embodiments of the battery monitoring unit according to the invention will be summarized and listed briefly as follows.

[1] A battery monitoring unit (110,210,310) comprising:

a plurality of voltage detection lines (29);

a flexible printed circuit board (27,27A,27B) extending in a stuck direction of single batteries;

an electronic circuit (48) connected to one end portions of the voltage detection lines so as to detect voltage of each of the single batteries and mounted on the flexible printed circuit board;

a plurality of busbar fixing portions (flexible bridge portions32,32A) formed integrally with the flexible printed circuit board and to which the plurality of the busbars are fixed respectively; and

communication lines (31) disposed in the flexible printed circuit board so as to connect between the electronic circuit and a battery ECU (20),

wherein the other end portions of the plurality of voltage detection lines (29) are respectively connected to the plurality of the busbars (13,13A) disposed in the stuck direction so as to electrically connect the plurality of the single batteries of a battery assembly (47),

wherein the plurality of the voltage detection lines are disposed in the flexible printed circuit board (27,27A,27B).

[2] The battery monitoring unit (110,210,310) according to the aforementioned configuration [1],

wherein the plurality of the busbar fixing portions include flexible bridge portions (32,32A) between adjacent ones of a plurality of opening portions (33,35) opening at predetermined interval in a row in the stuck direction, and

wherein each of the plurality of the opening portions (33,35) has an opening width (H) wider than a transverse-direction width (w) of each of the plurality of the busbars (13,13A), in a direction which is perpendicular to the stuck direction and a thickness direction of the plurality of the busbars.

[3] The battery monitoring unit (110,210,310) according to the aforementioned configuration [2],

wherein the plurality of the busbars (13,13A) are soldered and fixed to lands (30,30A) positioned and extending on the flexible bridge portions (32,32A) from the other end portions of the plurality of the voltage detection lines (29) respectively.

[4] The battery monitoring unit (110,210,310) according to any one of the aforementioned configurations [1] through [3],

wherein a gas discharging duct (45) extending in the stuck direction so as to discharge gas generated inside the single batteries (11) to the outside is disposed on upper surfaces (23) of the single batteries, and

wherein a portion of the flexible printed circuit board (27), on which the electronic circuit (48) is mounted, is disposed to be contact with an upper surface of the gas discharging duct.

REFERENCE SIGNS LIST