JP6978483B2 - Battery system voltage detection circuit, battery system voltage detection circuit manufacturing method and battery system - Google Patents

Description

The present invention relates to a voltage detection circuit for a battery system and a battery system.

In order to extend the cruising range of a car, it is necessary to increase the output of the battery. In order to increase the output of the battery, a battery system in which a plurality of battery cells are connected in series is used. Even if the plurality of battery cells constituting such a battery system are the same, each of them has substantially different characteristics. Therefore, by repeating charging and discharging, the remaining capacity and the voltage of each are inconsistent. Become in equilibrium. The voltage imbalance forces some battery cells to be excessively charged and discharged, and the imbalance between the battery cells further progresses, so that the original output of the battery system as a whole cannot be obtained. Therefore, conventionally, the battery system includes a voltage detection circuit that monitors and detects the voltage of each battery cell in order to control the charging / discharging current by the voltage control unit (sub computer).

The voltage detection circuit includes a voltage detection unit, a voltage detection line (harness) connecting the plurality of battery cells and the voltage detection unit. This voltage detection line is manually assembled around the battery system using a simple bundling tool, but most of the voltage detection line is exposed to the outside.

The voltage detection line as described above not only spoils the appearance, but also has a problem that the work efficiency is deteriorated because the assembly is manual work. Further, even if a binding tool that shields the entire bundle is used so that the bundle of the voltage detection lines is not exposed to the outside, the diameter of the bundle is increased in order to shield the voltage detection lines corresponding to the number of battery cells. If it becomes large and is assembled to the outside of the battery system, the appearance is still spoiled, the storability is deteriorated, and there is a risk that the final installation inside the vehicle body will be hindered. In particular, in the future, as the number of battery cells increases in order to increase the output, the number of voltage detection lines also increases, so that there is a problem that the diameter of the bundled bundle also increases.

Therefore, conventionally, a battery system has been proposed in which the voltage detection line is mounted on a flexible substrate and arranged on a surface of a plurality of battery cells on the electrode terminal side (see, for example, Patent Document 1).

International Publication No. 2014/0244552

However, in the prior art, since the voltage detection circuit composed of the correction circuit, the memory, and the detection unit is mounted on the rigid board, it has at least two components, a flexible board and a rigid board, and both are connected. There was a problem that a workload was generated. Further, since the number of parts is large and the rigid substrate is used, there is a problem that the weight reduction of the entire battery system is impaired.

Further, the bus bar connecting the adjacent battery cells also has to be wired separately from the flexible board and must be connected to the flexible board, which further increases the number of parts and causes a workload.

The purpose of the disclosure in this specification is to solve the above-mentioned problems, and to provide a voltage detection circuit and such a voltage detection circuit capable of reducing the number of parts of the voltage detection circuit and reducing the mounting work load. It is intended to provide an installed battery system.

In order to achieve the above object, the voltage detection circuit disclosed in the present specification includes a voltage detection line constituting the voltage detection circuit and a voltage detection unit that monitors the remaining capacity of each battery cell and detects the voltage. The most important feature is that it is formed on a flexible substrate.

That is, it is a voltage detection circuit for a battery system that detects the voltage of a plurality of battery cells constituting the battery system for an automobile.
At least, a voltage detection line connected to the electrode terminals of the battery cells located at both ends of the battery system and the electrode terminals between the battery cells located in the middle, respectively.
A voltage detection unit that obtains the voltage applied to the voltage detection line and detects and monitors the remaining capacity of each battery cell .
It is composed of a flexible base film of a thin film insulator, an adhesive layer, and a conductor foil, and the voltage detection line and the voltage detection unit are laminated in order, and the surface on the arrangement side of each electrode terminal to which the plurality of battery cells are connected in series. a rectangular flexible substrate including a rectangular to match the shape,
Have,
The flexible substrate is arranged in an array on the opposite edge portions in the longitudinal direction of the rectangular shape, and is interposed between the bus bar for electrically connecting the adjacent electrode terminals in series and the voltage detection line, and the electrode terminals. It is characterized by having a fixing portion for connecting the voltage detection line and the voltage detection line and fixing the voltage detection line to each battery cell.

According to this configuration, in addition to the voltage detection line, all the various electronic components constituting the voltage detection unit can be mounted on the flexible substrate. The rectangle referred to here is not limited to a quadrangle whose apex angle is 90 degrees, and whether the angle has an R shape or a taper is formed, other indefinite shapes are angles. Alternatively, it may be provided on each side.

Before Symbol flexible substrate, wherein the fixing unit is mounted and the voltage detecting lines and the voltage detection section in an intermediate portion sandwiched between the edges which are arranged and formed, the array-side electrode terminals of the plurality of battery cells Any structure may be used as long as it can be mounted according to the shape of the surface.

According to this configuration, a fixing portion connecting the voltage detection line and the bus bar can also be provided on the flexible substrate and compactly mounted on a plurality of battery cells.

Further, the bus bar may be made of aluminum and may be joined to the fixed portion to integrate the flexible substrate and the bus bar.

According to this configuration, the bus bar itself can be provided on the flexible substrate.

The voltage detection circuit for a battery system disclosed in the present specification is waterproofed with an exterior material except for the voltage detection part of the flexible substrate on which the voltage detection line and the voltage detection part are mounted and the energized part of the bus bar. You may. The exterior material may be, for example, a thermoplastic film bonded by vacuum laminating. Further, the voltage detection circuit for a battery system disclosed in the present specification individually surrounds the bus bar with a waterproof coating of the exterior material in order to insulate and protect the bus bar bonded to the fixed portion. It may be configured to have a resin cover arranged and fixed.

According to this configuration, waterproofing can be performed according to the unevenness of the voltage detection circuit for the battery system. Further, the waterproof coating makes it possible to dispose and fix the resin cover.

To achieve the above object, the automotive battery system disclosed herein is an automotive battery system consisting of a battery block formed by interconnecting and arranging a plurality of battery cells.
The battery block is formed in a rectangular parallelepiped, and the voltage detection circuit for the battery system is mounted along the shape of the array-side surface of each electrode terminal of the plurality of battery cells.
The most important feature of the voltage detection circuit for a battery system is to have a sub computer that controls charging / discharging of each battery cell connected via a bus.

According to this configuration, a flexible board on which the voltage detection circuit for the battery system is mounted is mounted on the battery cell, and each battery cell constituting the battery system is connected to the voltage detection circuit, while the sub computer is used. , It becomes possible to arrange it at a position away from the battery block.

It is a method of manufacturing a voltage detection circuit for a battery system that detects the voltage of a plurality of battery cells constituting the battery system for an automobile.
The process of laminating the conductor layer and the flexible base film to form a flexible substrate of a rectangular sheet,
A step of forming an etching resist layer on the surface on the conductor layer side, which is a voltage detection circuit forming surface, and
A voltage detection line forming a voltage detection circuit pattern is formed by etching the surface on which the etching resist layer is formed, and the voltage detection line and the battery cell are formed on opposite edges of the rectangular sheet in the longitudinal direction. Each electrode terminal of the above is interposed between the bus bar for electrically connecting in series, the electrode terminal and the voltage detection line are connected, and a fixing portion for fixing the bus bar to each battery cell is formed. The process of removing the resist layer and
In order to protect the voltage detection line, a step of printing the solder resist and a step of printing the solder resist, except for the land portion connecting the fixed portion and the electronic component constituting the voltage detection portion.
The process of punching the outer shape into a predetermined shape to connect to the bus bar,
A step of arranging the bus bar so as to be electrically connectable to the fixed portion punched out from the outer shape, and
In order to insulate and protect the adjacent bus bars, a step of temporarily fixing a resin cover that individually surrounds the bus bars to a predetermined position, and
The process of masking the bus bar surrounded by the land portion and the resin cover, and
A step of waterproofing the flexible substrate after the masking step with an exterior material and fixing the resin cover to the flexible substrate.
The most important feature is to have a step of removing the masking.

According to this configuration, the voltage detection line, the voltage detection unit, the bus bar, and the resin cover can be integrally manufactured so as to be mounted on the battery system.

According to the method for manufacturing the voltage detection circuit for a battery system and the voltage detection circuit for a battery system disclosed in the present specification, it is possible to reduce the number of parts of the voltage detection circuit and reduce the installation work load. Play. Further, the battery system equipped with the voltage detection circuit for the battery system disclosed in the present specification has an effect that the voltage detection circuit for the battery system can be compactly mounted on the battery block.

FIG. 1 is a schematic circuit diagram illustrating an exemplary battery system disclosed herein. FIG. 2 is a perspective view of the battery system disclosed herein. FIG. 3 is a schematic side view showing a state in which a flexible substrate is mounted on a battery system. FIG. 4 is a top view of a flexible substrate on which the voltage detection unit disclosed in the present specification is mounted. FIG. 5 is a modified example of a schematic side view showing a state in which a flexible substrate is mounted on a battery system. FIG. 6 is a partial exploded view showing a procedure for attaching a flexible substrate and a bus bar to the electrode terminals of a battery cell. FIG. 7 is a partially enlarged view showing an embodiment in which a bus bar is integrally joined to a flexible substrate. FIG. 8 is a partially enlarged view showing a modified example of the embodiment in which the bus bar is integrally joined to the flexible substrate. 9A and 9B are schematic views illustrating waterproofing by vacuum laminating disclosed in the present specification, FIG. 9A is a diagram in which a flexible substrate is installed in a vacuum laminating device, and FIG. 9B is a diagram in a vacuum laminating device. Is vacuumed and heated, FIG. 3C is a diagram in which a film is pneumatically molded, and FIG. 3D is a diagram showing a state in which masking is removed. FIG. 10 is a partial perspective view showing a state in which the resin cover is arranged and fixed to the bus bar. FIG. 11 is a processing flow diagram of a method for manufacturing a voltage detection circuit for a battery system disclosed in the present specification.

Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. When the subsequent embodiments have components corresponding to the embodiments described above, they are designated by the same reference numerals and duplicated description will be omitted. Further, when only a part of the configuration is described in each embodiment, the reference code of the embodiment described above may be used for the other parts of the configuration. Even if it is not explicitly stated that the combinations are possible in each embodiment, it is possible to partially combine the embodiments as long as the combination does not cause any trouble.

FIG. 1 is a schematic circuit diagram schematically showing an embodiment of a battery system 1 for an automobile disclosed in the present specification. FIG. 1 describes only the configurations necessary for the description of the present embodiment, and the description of various electronic components and the like is omitted.

The battery system 1 has a battery block 2 composed of a plurality of battery cells 2A, 2B, 2C ... 2N, and a voltage detection circuit. The voltage detection circuit consists of at least a voltage detection unit 4 and a voltage detection line 5 connecting one to the electrode terminals of each of the battery cells 2A, 2B, 2C ... 2N and the other to the voltage detection unit 4. It is composed. Of the battery cells 2A, 2B, 2C ... 2N, the battery cells adjacent to each other have different electrode terminals 21 facing each other. That is, to explain exemplarily, the negative electrode terminal 21 of the battery cell 2A and the positive electrode terminal 21 of the battery cell 2B are adjacent to each other. Then, the two electrode terminals 21 having different electrodes adjacent to each other are connected via the bus bar 3. Battery cells other than the battery cells 2A and the battery cells 2B that are adjacent to each other are also connected in the same manner, and the battery cells 2A, 2B, 2C ... 2N are connected in series as the whole battery system.

The voltage detection unit 4 is connected to the sub computer 8 via the bus 7. The voltage of the battery cells 2A, 2B, 2C ... 2N detected by the voltage detection unit 4 is controlled by the subcomputer 8 to charge and discharge each battery cell 2A, 2B, 2C ... 2N, and each battery cell 2A, 2B, 2C. … Correct the 2N voltage imbalance.

In the voltage detection circuit of the battery system 1, a voltage detection unit 4 other than the sub computer 8 and a voltage detection line 5 are mounted on a flexible substrate 6.

FIG. 2 is a perspective view of the battery system 1 disclosed herein, and FIG. 3 is a schematic side view of the battery system 1. The battery cells 2A, 2B, 2C ... 2N are connected in series as described in FIG. 1, but a rectangular parallelepiped battery block 2 is formed by the entire battery cells 2A, 2B, 2C ... 2N.

As shown in FIG. 3, the upper surface of the battery block 2 has notched stepped portions 23 formed at both ends of the upper side portion in the side view on the short side, and the convex upper side is formed between the stepped portions 23 at both ends. The portion 22 is formed. The electrode terminals 21 of the battery cells 2A, 2B, 2C ... 2N are arranged on the step portion 23. That is, the electrode terminals 21 of the battery cells 2A, 2B, 2C ... 2N are arranged in a row along the stepped portions 23 continuously formed on both sides in the longitudinal direction of the battery block 2. When the battery block 2 is installed in an automobile, a space region is formed by both sides of the upper side portion 22 in the longitudinal direction and the step portion 23. This space area becomes a ventilation space during traveling, and the effect of cooling and dissipating heat generated by the operation of the battery cells 2A, 2B, 2C ... 2N can be expected.

The flexible substrate 6 is bent and mounted along the shape of the upper surface formed by the upper side portion 22 and the step portion 23 of the battery block 2, that is, the shape of the surface of each electrode terminal 21 on the array side.

The flexible substrate 6 is also formed in a rectangular shape substantially the same as the shape of the upper surface of the battery block 2. Hereinafter, the voltage detection circuit mounted on the flexible substrate 6 will be described with reference to FIG.

As described above, the edge portion 62 facing the flexible substrate 6 in the longitudinal direction is mounted on the electrode terminal 21 when the flexible substrate 6 is bent and mounted, and the intermediate portion 61 sandwiched between the two edge portions 62 is the upper side. It is attached to the portion 22. A voltage detection unit 4 and a voltage detection line 5 are mounted on the intermediate unit 61. That is, only the intermediate portion 61 is used to mount the voltage detection unit 4 and the voltage detection line 5. If the voltage detection line 5 or the voltage detection unit 4 is provided at the bent portion (LL line) of the edge portion 62, the voltage detection unit 4 and the voltage detection line 5 mounted by the bending may be peeled off. Therefore, in order to stably hold the mounted voltage detection unit 4 and the voltage detection line 5, the mounting region is set as the intermediate portion 61.

The edge portion 62 is bent into an L shape along the shape of the step portion 23. On the edge portion 62, a plurality of fixing portions 51 formed orthogonally to the longitudinal direction of the edge portion 62 are arranged and formed at predetermined intervals. In the present embodiment, the fixing portion 51 has a shape in which the center of the rectangular protruding portion is opened in a ring shape.

The fixing portions 51 are arranged and formed at predetermined intervals. When the battery cells 2A, 2B, 2C ... 2N are used for a long time, thermal expansion causes a shift in the arrangement direction of the electrode terminals 21 between the battery cells 2A, 2B, 2C ... 2N and the fixed portion 51. If the fixing portion 51 is provided with the ring-shaped opening as described above in the sheet of one flexible substrate, the fixing portion 51 may be twisted or broken in some cases due to the deviation. Therefore, in order to absorb the deviation, a predetermined clearance portion 63 is provided between the adjacent fixing portions 51.

The periphery of the opening of the fixing portion 51 is made of a conductor foil. The conductor foil of the fixed portion 51 is connected to a fixed portion connecting line 52 connected to the voltage detection line 5 of the intermediate portion 61. Therefore, since the electrode terminal 21 is electrically connected to the voltage detection line 5 via the bus bar 3, the fixed portion 51, and the fixed portion connecting line 52, the voltage of the battery cells 2A, 2B, 2C ... 2N is voltageed. It can be sent to the detection unit 4.

The flexible substrate 6 may be a flexible base film made of a thin film insulator. If high-temperature solder is used when mounting electronic components, it may adversely affect the electronic components. Therefore, mounting with low temperature solder is preferable. The flexible base film is not limited as long as it is a material that can be mounted by low temperature solder, but polyethylene terephthalate is particularly preferable.

The flexible substrate 6 has an adhesive layer on the flexible base film of the thin film insulator, and a conductor foil is formed on the adhesive layer as a voltage detection line 5. Specifically, copper foil and aluminum foil are used as the conductor foil. However, in order to reduce the weight, aluminum foil is preferable to copper foil.

FIG. 5 is a modification of the battery block, and is a schematic side view of the modification corresponding to the battery block 2 of FIG. Similar to the battery block 2 in FIG. 3, the battery block 201 constituting the battery system 11 has electrode terminals 2011 arranged on both sides in the longitudinal direction, and the adjacent electrode terminals 2011 are connected by a bus bar 3. Unlike the battery block 2 in FIG. 3, the battery block 201 does not have a space area like the step portion 23, and the upper side portion 2012 is flat. Therefore, as shown in FIG. 3, the flexible substrate 601 can be mounted on the upper side portion 2012 of the battery block 201 in a flat state without being bent.

For example, when the battery cell constituting the battery system is an all-solid-state battery, it is more resistant to heat and can be miniaturized than a lithium-ion battery, so that the shape of the step portion 23 is not required and the upper side portion 2012 It becomes possible to form it flat. Further, by flattening the upper side portion 2012, the flexible substrate 601 can be bent and mounted as described above, and the mounting area of the voltage detection portion and the voltage detection line is not limited to the intermediate portion as shown in FIG. (Not shown).

Hereinafter, a procedure for mounting the flexible substrate 6 and the bus bar 3 on the electrode terminal 21 will be described with reference to FIG. Note that FIG. 6 describes the electrode terminal 21A of the battery cell 2A and the electrode terminal 21B of the battery cell 2B as examples.

For example, if the electrode terminal 21A of the battery cell 2A is a negative electrode, the electrode terminal 21B of the battery cell 2B is a positive electrode. The electrode terminal 21A of the adjacent battery cell 2A and the electrode terminal 21B of the battery cell 2B are electrically connected by the bus bar 3. That is, the battery cell 2A and the battery cell 2B are connected in series. The bus bar 3 is screwed to the electrode terminal 21A and the electrode terminal 21B by a screw 24. Such connections are made continuously according to the arrangement, and all battery cells 2A, 2B, 2C ... 2N are connected in series.

The fixing portion 51 is interposed between the electrode terminal 21B and the bus bar 3, and is screwed together with the electrode terminal 21B and the bus bar 3 by a screw 24 in accordance with the ring-shaped opening. By applying this screwing to all the electrode terminals 21 and the bus bar 3, the edge portion 62 is fixed to the battery block 2.

FIG. 7 is a diagram showing a form in which the bus bar 3 is integrally joined to the flexible substrate 6 according to the embodiment. In the above embodiment, the bus bar 3 and the flexible board 6 are separate parts, and the flexible board 6 is mounted on the edge portion 62 by bending the flexible board 6 and aligning the fixing portion 51, the electrode terminal 21, and the bus bar 3. After that, the process of screwing is repeated. In the present embodiment, the mounting process can be further simplified by integrally joining the bus bar 3 and the flexible substrate 6.

Specifically, the bus bar 3 and the fixing portion 51 may be joined and integrated by a joining means such as welding or soldering, or may be integrally molded. In the present embodiment, the extending portion 51A is provided in order to make the joint surface of the fixing portion 51 large.

As described above, in order to reduce the weight of the flexible substrate 6, it is preferable that the bus bar 3 is also made of aluminum. For example, as compared with the copper bus bar 3, if the volume is the same, the weight of aluminum can be reduced by about 1/3, and if the resistance is the same, the weight can be reduced by about 1/2. However, in the case of joining with solder, since the fixing portion 51 is made of aluminum foil as described above, an oxide film is easily formed, the melted solder is repelled, and the solder wettability is lowered. Therefore, a coating layer such as nickel and gold or tin may be formed on the fixing portion 51 of the aluminum foil.

In addition to bonding by soldering, bonding may be performed by ultrasonic welding. With ultrasonic welding, welding time is short, low cost, and high-strength bonding is possible.

FIG. 8 is a diagram showing a modified example of the form in which the bus bar 3 of FIG. 7 is integrally joined. FIG. 8 shows a form in which the bus bar 3 is arranged under the fixed portion 51 and joined to the fixed portion 51, while FIG. 7 shows a form in which the bus bar 3 is arranged and joined on the fixed portion 511. That is, the fixed portion 511 is formed on the edge portion 621 via the fixed portion connecting line 521, and the bus bar 3 is joined thereto. In FIG. 7, the clearance portion 63 between the adjacent fixing portions 511 is formed by the base material of the flexible substrate, but in the embodiment of FIG. 8, the slit-shaped clearance portion 631 is formed.

By the way, since the voltage detection unit 4 mounted on the flexible substrate 6, that is, the electronic components and the like are mounted on the battery block 2 in an exposed state, it is preferable to waterproof the flexible substrate 6 with an exterior material. ..

In the conventional battery system, since the voltage detection line and the voltage detection unit are not integrated, both are connected via a wire harness or a flexible substrate as a substitute thereof. When connecting in such a form, a plug-in type connector is required. However, it is difficult to completely waterproof the plug-in type connector. In particular, since wire aggregation is indispensable, there is a problem that it is very difficult to remove water from a connector that aggregates a high potential difference in the in-vehicle field driven by a high voltage. In such a case, as a possible countermeasure method for those skilled in the art, for example, a method of setting a limit value in the voltage by using a fuse can be considered. However, there is a problem that a sufficient effect cannot be obtained by such a countermeasure method, such as when a high voltage is generated in an extremely short time or when the fuse itself is short-circuited by moisture.

Since the flexible substrate 1 disclosed in the present specification is equipped with a voltage detection line 5 and a voltage detection unit 4 integrated therein, the above-mentioned problems occur even if the waterproof coating is provided with an exterior material. do not do.

Since the waterproof coating has irregularities on the outer surface of the voltage detection unit 4, an exterior material that can be coated along the shape is preferable. For example, a waterproof coating is possible even with a resin coating, but in order to exert a certain waterproof effect, it is necessary to apply a thick resin. As described above, the voltage detection unit 4 must be centrally mounted on the intermediate portion 61 of the flexible substrate 6, but if the resin is thickly coated, mounting may be hindered due to space saving. Further, in the case of resin coating, a work process such as curing and curing is required after the resin is applied, which may lead to a decrease in work efficiency.

From the above, as the exterior material, a thermoplastic film laminated by vacuum laminating is suitable. The waterproof coating with the thermoplastic film may be performed, for example, by the procedure shown in FIG. That is, the flexible substrate 6 is installed in the vacuum laminating device V, and the adhesive surface of the thermoplastic film F is stretched on the upper portion at a position facing the waterproof coating surface (upper surface) of the flexible substrate 6 (FIG. 9A). .. Next, the inside of the vacuum laminating device V in which the thermoplastic film F and the flexible substrate 6 are installed is evacuated from the surface of the thermoplastic film F opposite to the adhesive surface with the heater H to set a vacuum atmosphere. (FIG. 9 (B)). Then, a pressure P is applied from the opposite surface of the exterior film F toward the upper surface of the flexible substrate 6 by compressed air, and the entire upper surface of the flexible substrate 6 is covered with the thermoplastic film F (FIG. 9 (FIG. 9). C)). Before the waterproof coating, masking is applied to the non-waterproof coating portion such as the energized portion of the flexible substrate F, and after the step of FIG. 9C, the flexible substrate 6 is installed at the masked portion and the vacuum laminating device V. The film at the end of the vacuum is removed (FIG. 9 (D)). By the above procedure, the waterproof coating can be applied according to the unevenness of the outer surface of the flexible substrate 6. The waterproof coating by vacuum lamination is preferably formed so that the voltage detection line 5 and the electrode terminal 21 of the battery can be connected so that a part of the flexible substrate is exposed. Therefore, when the fixed portions 51 and 511 are arranged and formed on the flexible substrate 6, the fixed portions 51 and 511 may also be masked and waterproofed.

Further, as shown in FIG. 10, when the resin cover 9 that individually surrounds each bus bar 3 is arranged for the purpose of insulating protection of the adjacent bus bars 3, the periphery of each bus bar 3 fixedly installed on the fixed portion 511. Temporarily fix the resin cover 9 to the. The resin cover 9 is formed of a bottomless rectangular parallelepiped that surrounds the periphery of the bus bar 3 fixed on the fixing portion 511. Therefore, if the waterproof coating by the vacuum laminate is applied in the temporarily fixed state, the upper surface open portion (open portion) of the resin cover 9 may be blocked and the energization may be hindered. Therefore, the waterproof coating may be applied with the upper surface open portion masked, and the masking may be removed in the step of FIG. 9D. After the waterproof coating, the resin cover 9 is fixed on the flexible substrate 6 by the thermoplastic film F. Therefore, it is possible to dispose and fix the resin cover 9 at the same time as the waterproof coating. Note that FIG. 10 is a diagram in which the resin cover 9 is arranged and fixed in the modified example described in FIG. 8, but the method of arranging and fixing the resin cover 9 is the same even in the form described in FIG. (Not shown).

According to the waterproof coating by vacuum laminating, it is possible to coat with a thinner film as compared with the resin coating while maintaining the waterproof effect, and the space saving is not hindered. Further, since the coating work is completed by evacuation, steps such as curing and curing of the resin are unnecessary, and work efficiency is improved. Further, by evacuating, air (air bubbles) between the exterior material (laminated film) and the flexible substrate 6 can be eliminated, so that dew condensation occurs due to temperature changes and the like, which adversely affects various electronic components. Such obstacles are unlikely to occur.

As described above, the flexible substrate 1 disclosed in the present specification is extremely reliable because it can be vacuum-formed on the substrate on which the voltage detection line 5 and the voltage detection unit 4 are integrally mounted. Highly waterproof processing has become possible.

Hereinafter, a method of manufacturing a voltage detection circuit for a battery system will be described with reference to FIG.

A conductor layer serving as a base material for a flexible substrate, for example, an aluminum foil and a flexible base film, for example, polyethylene terephthalate are laminated (S1), and the laminated base material is used to mount the flexible substrate on the upper surface of a battery block. Is formed into the shape of the upper surface, that is, a rectangular shape (S2). An etching resist layer is formed on the rectangularly formed base material (S3). By etching (aluminum etching when an aluminum foil is used as described in S1) and removal of the resist layer, a fixed portion of the voltage detection line and the bus bar, that is, a circuit pattern is formed (S4, S5). A solder resist is printed in order to form an insulating film that protects the surface of the flexible substrate on which the circuit pattern is formed (S6).

As described with reference to FIG. 4, the fixed portion formed by the aluminum etching is externally punched into a shape in which the center of the rectangular protruding portion is opened in a ring shape (S7). As described with reference to FIG. 6, this opening can be used as a positioning of the fixed portion when the fixed portion is interposed between the bus bar and the electrode terminal of the battery cell and screwed. In the present embodiment, the fixed portion is plated with nickel gold and then punched out.

The bus bar is joined to and arranged in the fixed portion in accordance with the opening punched out (S8). As described with reference to FIG. 7, the joining of the bus bar to the fixed portion may be performed by soldering, ultrasonic welding, or the like. Next, as described with reference to FIG. 10, the resin cover surrounding each bus bar arranged in the fixing portion is temporarily fixed on the flexible substrate (S9). The portion where the flexible substrate is mounted on the upper surface of the battery block and energized, that is, the open portion on the upper surface of the bus surrounded by the temporarily fixed resin cover and the land portion of the circuit pattern are masked (S10) and described with reference to FIG. as was to waterproof coated flexible base plate in the outer package (S11). After the waterproof coating is completed, the masking is removed (S12). Through the above steps, it is possible to manufacture a flexible substrate for a battery system in which a bus bar and a resin cover are integrated.

As described above, by mounting the flexible substrate 6 on which the voltage detection unit 4 and the voltage detection line 5 are mounted on the battery block 2, the entire battery system 1 can be miniaturized. Further, by forming the pattern of the voltage detection line 5 with aluminum foil and using aluminum as the material of the bus bar 3, the weight of the entire battery system 1 can be reduced.

In recent years, there has been an increasing demand for extended cruising range for electric vehicles, and it is expected that the number of connected battery cells will be further increased. The radiant heat generated by the increase in the number of battery cells raises the temperature around the battery system, causing the subcomputer that controls the charging and discharging of each battery cell to malfunction or stop functioning. Therefore, the sub-computer (furthermore, the ECU connected to the sub-computer) needs to be installed in a place as far as possible from the battery block composed of a plurality of battery cells.

On the other hand, in general, the voltage detection circuit and the subcomputer are closely connected to control the charging / discharging of the battery cell. However, as described above, when the subcomputer is installed in a place away from the battery block, the voltage is applied. The physical increase in the wiring material of the detection circuit complicates the assembly work and spoils the appearance of the battery system. Further, as the number of battery cells increases, the total length of the battery block is extended, the difference in the distance from both ends to the voltage detection unit becomes remarkable, and the electric resistance of the circuit is different.

Therefore, if the voltage detection circuit can be mounted on the battery block, the above-mentioned problem will be solved.

In the battery system 1 disclosed in the present specification, the flexible substrate 6 on which the voltage detection unit 4 and the voltage detection line 5 are mounted is provided with the shape of the surface of each of the electrode terminals 21 of the plurality of battery cells 2A, 2B, 2C ... 2N on the arrangement side. A bus bar 3 that electrically connects the voltage detection circuit composed of the mounted flexible substrate 6 and the electrode terminals 21 of the adjacent battery cells among the plurality of battery cells 2A, 2B, 2C ... 2N. And, and a sub computer 8 that controls charging and discharging of each battery cell based on the voltage detected by the voltage detection unit 4 from a plurality of battery cells 2A, 2B, 2C ... 2N, is connected via the bus 7. , It is configured to be separated from the battery block 2. Therefore, by compactly mounting the voltage detection circuit on the battery block 2, even if the number of battery cells increases, the quantity of wiring materials is suppressed, the appearance is not impaired, and the voltage detection unit 4 is further used. Can be wired in the shortest distance. Further, since the sub computer 8 is separated from the battery block 2, the influence of radiant heat generated by the increase in the number of battery cells can be suppressed.

1,11 Battery system 2,201 Battery block 2A, 2B, 2C, 2N Battery cell 3 Bus bar 4 Voltage detector 5 Voltage detection line 6,601 Flexible board 7 Bus 8 Subcomputer 9 Resin cover 21, 2011 Electrode terminal 22 Upper side 23 Stepped part 24 Screw 51, 511 Fixed part 52, 521 Fixed part Connection line 61 Intermediate part 62, 621 Margin part 63, 631 Free space part

Claims (11)

A voltage detection circuit for a battery system that detects the voltage of a plurality of battery cells constituting an automobile battery system.
At least, voltage detection lines connected to the electrode terminals of the battery cells located at both ends of the battery system and the electrode terminals between the battery cells located in the middle, respectively.
A voltage detection unit that obtains the voltage applied to the voltage detection line and detects and monitors the remaining capacity of each battery cell .
It is composed of a flexible base film of a thin film insulator, an adhesive layer, and a conductor foil, and the voltage detection line and the voltage detection unit are laminated in order, and the surface on the arrangement side of each electrode terminal to which the plurality of battery cells are connected in series. a rectangular flexible substrate including a rectangular to match the shape,
Have,
The flexible substrate is arranged in an array on the opposite edge portions in the longitudinal direction of the rectangular shape, and is interposed between the bus bar for electrically connecting the adjacent electrode terminals in series and the voltage detection line, and the electrode terminals. A voltage detection circuit for a battery system having a fixed portion for connecting the voltage detection line and the voltage detection line and fixing the voltage detection line to each battery cell. In the flexible substrate, the voltage detection line and the voltage detection unit are mounted in an intermediate portion sandwiched between the edge portions in which the fixing portions are arranged, and the array side of each electrode terminal of the plurality of battery cells is mounted. battery system voltage detecting circuit according to claim 1, wherein along the shape of the surface and is configured to be mounted. The voltage detection circuit for a battery system according to claim 1 or 2 , wherein the fixed portion has a clearance portion separated from the adjacent fixed portion at a predetermined interval. The voltage detection circuit for a battery system according to any one of claims 1 to 3 , wherein the flexible base film is made of polyethylene terephthalate. The voltage for a battery system according to any one of claims 1 to 4 , wherein the voltage detection line is made of aluminum foil, and the fixing portion is formed by forming a coating layer of nickel and gold or tin on the aluminum foil. Detection circuit. The voltage detection for a battery system according to any one of claims 1 to 5, wherein the bus bar is made of aluminum and is joined to the fixed portion to integrate the flexible substrate and the bus bar. circuit. Any one of claims 1 to 6 which is waterproofed with an exterior material except for the voltage detection part of the flexible substrate on which the voltage detection line and the voltage detection part are mounted and the energized portion of the bus bar. The voltage detection circuit for the battery system described. The voltage detection circuit for a battery system according to claim 7 , wherein the exterior material is made of a thermoplastic film bonded by vacuum lamination. For insulating protecting the busbar joined to the fixed part, the waterproof coating of the exterior material, according to claim 7 or claim 8 having disposed fixed resin cover to each separately enclosing the busbar The voltage detection circuit for the battery system described. A battery system for automobiles consisting of a battery block formed by connecting and arranging a plurality of battery cells to each other.
The voltage detection circuit for a battery system according to any one of claims 1 to 9 , wherein the battery block is formed in a rectangular parallelepiped and follows the shape of an array surface of each electrode terminal of the plurality of battery cells. Attached,
A battery system for an automobile, wherein the voltage detection circuit for the battery system includes a sub computer that controls charging / discharging of each battery cell connected via a bus. It is a method of manufacturing a voltage detection circuit for a battery system that detects the voltage of a plurality of battery cells constituting the battery system for an automobile.
The process of laminating the conductor layer and the flexible base film to form a flexible substrate of a rectangular sheet,
A step of forming an etching resist layer on the surface on the conductor layer side, which is a voltage detection circuit forming surface, and
A voltage detection line forming a voltage detection circuit pattern is formed by etching the surface on which the etching resist layer is formed, and the voltage detection line and the battery cell are formed on opposite edges of the rectangular sheet in the longitudinal direction. Each of the electrode terminals of the above is interposed between the bus bar for electrically connecting in series, the electrode terminal and the voltage detection line are connected, and a fixing portion for fixing the bus bar to each battery cell is formed. The process of removing the resist layer and
In order to protect the voltage detection line, a step of printing the solder resist and a step of printing the solder resist, except for the land portion connecting the fixed portion and the electronic component constituting the voltage detection portion.
The process of punching the outer shape into a predetermined shape to connect to the bus bar,
A step of arranging the bus bar so as to be electrically connectable to the fixed portion punched out from the outer shape, and
In order to insulate and protect the adjacent bus bars, a step of temporarily fixing a resin cover that individually surrounds the bus bars to a predetermined position, and
The process of masking the bus bar surrounded by the land portion and the resin cover, and
A step of waterproofing the flexible substrate after the masking step with an exterior material and fixing the resin cover to the flexible substrate.
A method for manufacturing a voltage detection circuit for a battery system, comprising a step of removing the masking.

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