JP2021077568A - Laminated bus bar, method for designing laminated bus bar, and battery module - Google Patents

Abstract

To provide a laminated bus bar having an FFC and having flexibility in which not only DC current but AC current can be allowed to flow through the bus bar, and has small heat generation and high heat radiation efficiency, a battery module to which the laminated bus bar is applied, and a method for designing a laminated bus bar which has small heat generation and through which large current can be allowed to flow.SOLUTION: A laminated bus bar in which a plurality of flexible flat cables (FFC) is laminated, in which each of the plurality of flexible flat cables (FFC) includes two organic resin films, a plurality of metal flat plates between the two organic resin films, and adhesive agent which adheres the two organic resin films and the plurality of metal flat plates, the adhesive agent is provided between adjacent metal flat plates, and thermal emissivity of each of the two organic resin films and the adhesive agent is higher than the thermal emissivity of the metal flat plates.SELECTED DRAWING: Figure 1A

Description

The present invention relates to a laminated busbar in which a so-called FFC (Flexible Flat Cable) in which a metal flat plate is formed on an organic resin film is laminated, and a design method thereof.

The bus bar is a component for connecting the power supply to each part. With the spread of next-generation vehicles such as hybrid vehicles and electric vehicles in recent years, it is expected that the demand for in-vehicle electronic devices and electric devices compatible with high voltage and large current will increase. Busbars are important parts as one of the parts for such next-generation automobiles.

Busbars function as so-called wiring components that electrically connect electronic components such as motors, inverters, or generators, electronic devices, or electronic devices. Generally, a large current flows through an in-vehicle bus bar, but depending on the electronic component, electronic device, electronic device, or electrical device, when not only direct current (DC) but also alternating current (AC) is passed through the bus bar. There is also.

When a large current is passed through the bus bar, it is necessary to increase the cross-sectional area of the metal bar in order to reduce the resistance of the metal bar of the bus bar. However, in the case of alternating current, even if the cross-sectional area of the metal bar of the bus bar is increased, the current flows only in the vicinity of the surface of the metal bar due to the skin effect. When the skin effect is taken into consideration, the surface depth δ of the metal rod through which the current flows is expressed as (Equation 1).

Here, ρ is the electrical resistivity of the metal rod, f is the frequency, and μ is the absolute transmittance of the metal rod. From (Equation 1), the higher the frequency of the alternating current, the more the current flows only near the surface of the metal rod. Therefore, in electronic parts, electronic devices, electronic devices, or electric devices that require alternating current, a bus bar made of a metal rod in a flat plate shape is used (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-310079

However, if the metal bar of the bus bar is flattened to reduce the cross-sectional area, the resistance of the metal bar increases. Therefore, it is difficult to use a bus bar having a flat metal rod when passing a direct current. Further, even when an alternating current is passed, the resistance of the direct current component becomes large, so that the effective resistance of the metal rod of the bus bar becomes large after all. Such an increase in the resistance of the metal rod of the bus bar is not preferable because it not only reduces the current flowing through the bus bar but also raises the temperature of the bus bar due to heat generation.

In view of the above problems, one of the problems of the present invention is to provide an FFC capable of passing not only a direct current but also an alternating current, generating a small amount of heat, and having high heat dissipation efficiency, and a flexible laminated bus bar. .. Another issue is to provide a battery module to which a laminated bus bar is applied. Another object of the present invention is to provide a method for designing a laminated bus bar that generates less heat and allows a large current to flow.

The laminated bus bar according to the embodiment of the present invention is a laminated bus bar in which a plurality of flexible flat cables (FFCs) are laminated, and each of the plurality of flexible flat cables (FFCs) has two organic resin films and two. A plurality of metal flat plates between one organic resin film and an adhesive for adhering the two organic resin films and the plurality of metal flat plates are included, and an adhesive is provided between the adjacent metal flat plates, and two. The thermal radiation coefficient of each of the organic resin film and the adhesive is higher than the thermal radiation coefficient of the metal flat plate.

The laminated bus bar according to an embodiment of the present invention is a laminated bus bar in which a plurality of flexible flat cables (FFCs) are laminated, and each of the plurality of flexible flat cables (FFCs) has two organic resin films and two. A plurality of metal flat plates between one organic resin film and an adhesive for adhering two organic resin films and a plurality of metal flat plates are included, and an adhesive is provided between adjacent metal flat plates, and a plurality of metal flat plates are provided. Of the flexible flat cables (FFC), two adjacent flexible flat cables (FFC) differ in the number of multiple metal flat plates contained in each, and the thermal radiation coefficient of each of the two organic resin films and the adhesive is metal. Higher than the heat radiation rate of the flat plate.

The thermal emissivity of the two organic resin films may be 0.8 or more. Further, the material of the two organic resin films may be polycyclohexanedimethylene terephthalate (PCT).

The material of the adhesive may be polyester.

The metal flat plate is a rectangle, and the length of the long side of the rectangle may be five times or more the length of the short side of the rectangle.

Less than or equal to the specific value obtained by using the physical quantity of the metal bar obtained under the predetermined conditions of the rigid bus bar using the material of the metal flat plate as the metal bar and the physical quantity of the metal flat plate corresponding to the physical quantity of the metal bar. The structure of the metal plate may be determined by using the physical quantity of the metal plate as a parameter.

The battery module according to the embodiment of the present invention electrically connects the first battery cell, the second battery cell, the electrode of the first battery and the electrode of the second battery cell, and a plurality of flexible flat cables ( Each of the plurality of flexible flat cables (FFC) includes a laminated bus bar in which FFC) is laminated, a plurality of metal flat plates between two organic resin films, and two organic resins. An adhesive for adhering the film and the plurality of metal flat plates is included, and an adhesive is provided between the adjacent metal flat plates, and the thermal radiation coefficient of each of the two organic resin films and the adhesive is a metal. Higher than the thermal radiation of the flat plate.

The first battery cell may be included in the first battery unit, and the second battery cell may be included in a second battery unit different from the first battery unit.

The method for designing a bus bar according to an embodiment of the present invention is to bond two organic resin films, a plurality of metal flat plates between the two organic resin films, and two organic resin films and a plurality of metal flat plates. A method for designing a laminated bus bar in which a plurality of flexible flat cables (FFCs) containing an agent and a metal plate are laminated, and the physical amount of the metal bar material under a predetermined condition of a rigid bus bar using a metal flat plate material as a metal bar material is determined. Acquire, obtain the physical amount of the metal flat plate under the predetermined conditions of the laminated bus bar, calculate a specific value using the physical amount of the metal bar and the physical amount of the metal flat plate, and make it equal to or less than the specific value. The structure of the metal plate is determined by using the physical quantity of the metal plate as a parameter.

The physical quantity of the metal bar is the cross-sectional area A ₁ of the metal bar, and the physical quantity of the metal flat plate is the total cross-sectional area A ₂ of the plurality of metal flat plates included in the plurality of laminated flexible flat cables (FFC). , The total cross-sectional area A ₂ of the plurality of metal flat plates may satisfy the following equation.

The cross-sectional area A ₁ of the metal rod may be 90 mm ^2.

It is a perspective view of the laminated bus bar which concerns on one Embodiment of this invention. It is a schematic side view of the laminated bus bar which concerns on one Embodiment of this invention. It is sectional drawing in the long side direction of the flexible flat cable of the laminated bus bar which concerns on one Embodiment of this invention. It is sectional drawing in the short side direction of the flexible flat cable of the laminated bus bar which concerns on one Embodiment of this invention. It is a side view which shows the structure for simulation of the laminated bus bar which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure for simulation of the laminated bus bar which concerns on one Embodiment of this invention. As a comparative example, it is a side view which shows the structure for simulation of the bus bar which does not contain an organic resin film and an adhesive. As a comparative example, it is sectional drawing which shows the structure for simulation of the bus bar which does not contain an organic resin film and an adhesive. It is a graph of each of the ^{square I 2} (x) of the current and the resistance R (x) with respect to the parameter x shown in the power loss _loss. It is a schematic side view of the laminated bus bar which concerns on one Embodiment of this invention. It is a schematic perspective view of the battery module 20 which concerns on one Embodiment of this invention.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. It should be noted that the embodiments are merely examples, and those which can be easily conceived by those skilled in the art by appropriately changing the invention while maintaining the gist of the invention are naturally included in the scope of the present invention. Further, in order to clarify the explanation, the drawings may be schematically represented by the width, thickness, shape, etc. of each part as compared with the actual aspect. However, the illustrated shape is merely an example and does not limit the interpretation of the present invention.

In the present specification and drawings, the same reference numerals are used when referring to a plurality of identical or similar configurations as a whole. In addition, hyphens and natural numbers may be used when distinguishing a plurality of parts in one configuration.

<First Embodiment>
First, the structure of the laminated bus bar and the theoretical mechanism related to the laminated bus bar according to the embodiment of the present invention will be described, and then the design method of the laminated bus bar will be described.

[1. Structure of laminated bus bar]
The structure of the laminated bus bar 10 according to the embodiment of the present invention will be described with reference to FIGS. 1A and 1B.

FIG. 1A is a perspective view of a laminated bus bar 10 according to an embodiment of the present invention. The laminated bus bar 10 has a structure in which a plurality of flexible flat cables (FFC) 100 are laminated. In the following, the long side direction of the FFC 100 will be described as the X direction, the short side direction of the FFC 100 as the Y direction, and the stacking direction of the FFC 100 as the Z direction.

The laminated bus bar 10 includes a main body portion 11 and terminal portions 12 provided at both ends of the main body portion 11. The main body portion 11 is an insulator portion, and the terminal portion 12 is a conductor portion. That is, the laminated bus bar 10 is electrically connected to another electronic component, electronic device, electronic device, or electric device by using the terminal portion 12. Although not shown, the main body 11 can be provided with a protective cover on the outside of the laminated FFC 110 in order to protect the FFC 100. Further, although not shown, the terminal portion 12 may be provided with a connector for connecting with another electronic component, an electronic device, an electronic device, or an electric device.

FIG. 1B is a schematic side view of the laminated bus bar 10. As shown in FIG. 1B, in the laminated bus bar 10, a plurality of FFC100-1, 100-2, ..., 100-n are laminated in the z direction. Here, when a plurality of FFCs are not particularly distinguished, they will be described as FFC100 for convenience. That is, in the laminated bus bar 10 of FIG. 1B, n layers of FFC 100 are laminated in the z direction.

In FIG. 1B, for convenience of explanation, the adjacent FFCs 100 of the laminated bus bars 10 are shown at intervals, but the adjacent FFCs 100 may not be provided at intervals. That is, a part of the adjacent FFC 100 may be in contact with each other. Further, the adjacent FFCs may be adhered by an adhesive.

Subsequently, the structure of the FFC 100 constituting the laminated bus bar 10 will be described with reference to FIGS. 2A and 2B.

FIG. 2A is a cross-sectional view of the FFC 100 in the long side direction (X direction), and FIG. 2B is a cross-sectional view of the FFC 100 in the short side direction (Y direction). As shown in FIGS. 2A and 2B, each of the plurality of FFC 100s has two organic resin films 110-1 and 110-2, a plurality of metal flat plates 120-1, 120-2, ..., 120-m, respectively. Also included is adhesive 130. Here, when a plurality of metal flat plates are not particularly distinguished, the metal flat plate 120 will be described for convenience. That is, in the FFC 100 of FIGS. 2A and 2B, m metal flat plates 120 are fixed between the two organic resin films 110-1 and 110-2 with an adhesive 130. Further, in the region sandwiched between the two organic resin films 110-1 and 110-2, the two adjacent metal flat plates 120 are not in contact with each other, and are between the two adjacent metal flat plates 120. Adhesive 130 is present.

On the other hand, in the X direction, the metal flat plate 120 includes a metal clad portion 121 projecting from the two organic resin films 110-1 and 110-2. That is, in the FFC 100, the metal clad portions 121 of the metal flat plate 120 are exposed at both ends in the X direction. The metal clad portions 121 of the plurality of metal flat plates 120 can be in contact with each other. Further, the metal clad portions 121 of the plurality of metal flat plates 120 can be in contact with each other not only in the one-layer FFC 100 but also in the n-layer FFC 100. The metal clad portions 121 of the plurality of metal flat plates 120 may be directly contacted, may be joined and contacted, or may be bonded using a conductive adhesive and may be contacted via the conductive adhesive. .. That is, the metal clad portions 121 of the plurality of metal flat plates 120 are electrically connected to each other to form the terminal portion 12 of the laminated bus bar 10.

Further, as described above, the terminal portion 12 of the laminated bus bar 10 may be provided with a connecting tool. Therefore, the metal clad portion 121 of the metal flat plate 120 may be joined to the connector and electrically connected. By providing the connecting tool, the plurality of metal flat plates 120 can be combined into one.

In the FFC 100, the metal flat plate 120 is preferably surrounded by the adhesive 130. That is, as shown in FIG. 2B, it is preferable that adhesives 130 are provided at both ends of the FFC 100 in the X direction, and the ends of the FFC 100 are adhered by the adhesive 130. However, the configuration of the end portion of the FFC 100 in the X direction is not limited to this. At the end of the FFC 100 in the X direction, a part of the metal flat plate 120 may be exposed from the organic resin films 110-1 and 110-2.

The film thicknesses of the organic resin films 110-1 and 110-2 and the adhesive 130 are 0.01 mm or more and 0.05 mm or less, preferably 0.02 mm or more and 0.05 mm or less, and particularly preferably 0.02 mm or more and 0.04 mm. It is as follows.

Specifically, the cross-sectional shape of the metal flat plate 120 is a rectangle as shown in FIG. 2B. When the metal flat plate 120 is rectangular, the long sides of the rectangle are in the direction parallel to the organic resin films 110-1 and 110-2 (that is, the X direction), and the short sides of the rectangle are the organic resin films 110-1 and 110-. The direction is perpendicular to 2 (that is, the Z direction). By forming the metal flat plate 120 in such a configuration, the area where the metal flat plate 120 overlaps with the organic resin films 110-1 and 110-2 increases, so that the heat loss and current loss of the FFC 100, which will be described later, can be reduced. it can. The cross-sectional shape of the metal flat plate 120 is not limited to a rectangle. The cross-sectional shape of the metal flat plate 120 may be, for example, an ellipse. In that case, the major axis of the ellipse is in the X direction, and the minor axis of the ellipse is in the Z direction.

When the metal flat plate 120 is rectangular, the length of the long side with respect to the length of the short side of the rectangle is 5 times or more, preferably 10 times or more, and particularly preferably 50 times or more. By increasing the difference between the length in the short side direction and the length in the long side direction of the rectangle, the metal flat plate 120 and the organic resin films 110-1 and 110-2 are superimposed even if the cross-sectional areas are the same. The area can be increased. Therefore, as long as the rigidity of the metal flat plate 120 can be maintained, the length in the long side direction with respect to the length in the short side direction may be 100 times or more.

As the material of the organic resin films 110-1 and 110-2, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polycyclohexanedimethylene terephthalate (PCT) or the like can be used. it can. PCT is particularly preferable as the material for the organic resin films 110-1 and 110-2 of FFC100. PCT has higher chemical resistance than PET or PEN, and is excellent in hydrolysis stability, electrical stability, and thermal stability.

The thermal emissivity of the organic resin films 110-1 and 110-2 is 0.7 or more and 1 or less, preferably 0.75 or more and 1 or less, and particularly preferably 0.8 or more and 1 or less. Since the organic resin films 110-1 and 110-2 are provided on the outermost side of the FFC 100, the thermal emissivity of the organic resin films 110-1 and 110-2 is larger than the thermal emissivity of the metal flat plate 120 and the adhesive 130. Is preferable. In particular, it is preferable that the heat emissivity increases in the order of the metal flat plate 120, the adhesive 130, and the organic resin films 110-1 and 110-2. The efficiency of heat dissipation is improved by increasing the heat emissivity toward the outside of the FFC 100.

As the material of the metal flat plate 120, for example, copper (Cu), silver (Ag), gold (Au), aluminum (Al), platinum (Pt), or an alloy thereof can be used. Cu is particularly preferable as the material of the metal flat plate 120 of the FFC 100. Since Cu has high electrical conductivity and is inexpensive, the manufacturing cost can be suppressed.

As the material of the adhesive 130, for example, polyester, acrylic, epoxy, or the like can be used. When the adhesive 130 is provided on the organic resin films 110-1 and 110-2, a primer may be applied to the organic resin films 110-1 and 110-2. By applying the primer, the adhesion between the organic resin films 110-1 and 110-2 and the adhesive 130 is improved.

The laminated bus bar 10 according to an embodiment of the present invention can reduce the amount of metal in the whole as compared with a bus bar made of ordinary bulk metal (hereinafter, referred to as a rigid bus bar). Therefore, the laminated bus bar 10 is lighter than the rigid bus bar, and the cost can be reduced. Further, unlike the rigid bus bar, the laminated bus bar 10 has an excellent flexibility because it has a structure in which FFC 100 is laminated. In a conventional rigid bus bar, if there is a bent portion, a considerable amount of heat is generated at the bent portion when power is supplied, so that more power is lost than when the rigid bus bar is not bent. On the other hand, even if the laminated bus bar is bent, there is almost no power loss due to the bending. Therefore, the laminated bus bar 10 has many advantages as compared with the rigid bus bar.

Further, the laminated bus bar 10 can suppress a temperature rise when a large current is applied. This can be explained by the fact that the laminated bus bar 10 has a smaller heat loss and current loss than the rigid bus bar. Therefore, the mechanism of heat loss and current loss in the laminated bus bar 10 will be described below.

[2. Heat loss]
The second law of thermodynamics is a law concerning the direction of energy transfer and the quality of energy, and is also a law related to entropy. For example, a heating wire heater can convert electrical energy into thermal energy. However, even if thermal energy is applied to the heating wire heater, it cannot be converted into electrical energy. Therefore, when comparing electric energy and thermal energy, electric energy is higher quality energy than thermal energy, and only conversion (transfer) from high quality electric energy to low quality thermal energy is possible.

Also, in the transfer of heat energy, for example, hot coffee cools, but cold coffee does not get hot (it gets hotter than the temperature of the air in which the coffee is placed). This is because the heat of hot coffee is transferred to the air, but it can be said that the entropy is increased by diffusing the heat energy into the air. That is, the thermal energy can move only in the direction in which the entropy increases.

Considering the bus bar of the power, not all power _{P appli} supplied to the bus bar is taken out as electric power _{P real,} arises the power loss _{P loss} is always a loss of electrical energy. This can be expressed by (Equation 2).

As mentioned above, according to the second law of thermodynamics, high quality electrical energy is converted into low quality thermal energy. Therefore, it can be said that the power loss _loss is converted from high-quality electric energy to low-quality thermal energy. Therefore, the bus bar will have the thermal energy corresponding to _{the power loss loss.} This thermal energy is released to the outside of the bus bar by heat transfer, namely heat conduction, convection, and heat radiation.

Heat conduction is the transfer of heat through a substance, and there is a substance-specific thermal conductivity as a standard for the ease of heat transfer of a substance. Convection is the transfer of heat by the flow of fluid. Heat radiation is the transfer of heat by electromagnetic waves, and the heat emissivity peculiar to a substance is a standard for the ease of releasing heat of a substance. Here, it is considered that there is no influence of convection (for example, air convection) in the environment where the bus bar is placed, and heat conduction and heat radiation are considered in the heat transfer of the bus bar.

Heat conduction is expressed by Fourier's law as shown in (Equation 3).

Here, Q _F is the amount of heat transfer due to heat conduction, k is the thermal conductivity of the substance, A is the cross-sectional area of the substance, and ∇ T is the temperature gradient.

Further, heat radiation is expressed as (Equation 4) according to Stefan-Boltzmann's law.

Here, Q _SB is the amount of heat transfer due to heat radiation, σ is the Stefan-Boltzmann constant (= 5.67 × ^10-8 (W / m ² · K ⁴ )), and T ₁ is the temperature of substance 1. The actual heat radiation is _{the difference from the temperature T 2} of the transferred substance 2, and since the substance 1 is not a complete blackbody, it depends on the emissivity ε (0 <ε <1) of the substance 1 and ( It is expressed as in equation 5).

As can be seen from (Equation 3) and (Equation 5), if the thermal conductivity of the substance is large, the thermal conductivity is large, and if the thermal radiation conductivity of the substance is large, the thermal radiation is large. Therefore, it is preferable to use a conductor having a large thermal conductivity and thermal emissivity as the bus bar.

In the case of a rigid bus bar, Cu is often used as the metal bar. The thermal conductivity of Cu is as high as about 400 (W / m · K), but the thermal emissivity of Cu is very low as about 0.03. This means that the heat transfer inside Cu is fast, but the heat release to the outside is extremely small. Therefore, in the case of a rigid bus bar using Cu, heat is not released to the outside and heat tends to be accumulated inside. Therefore, the temperature of the rigid bus bar tends to rise.

On the other hand, in the case of the laminated bus bar 10, even when Cu is used for the metal flat plate 120, the materials in contact with the outside are the two organic resin films 110-1 and 110-2, and the adhesive 130. As described above, the materials of the organic resin films 110-1 and 110-2 are organic resin materials such as PET, PEN, or PCT. The thermal conductivity of these organic resin materials is as low as 0.2 to 0.4 (W / m · K). On the other hand, the thermal emissivity of the organic resin material is as high as 0.84 to 0.95, although it depends on the presence or absence of coloring. The same applies to the adhesive 130.

_{Here, using (Equation 5), the heat transfer amount QSB} due to heat radiation is calculated for each of the rigid bus bar using Cu and the laminated bus bar 10 using Cu on the metal flat plate 120.

A rigid bus bar using a typical Cu having an allowable current of 300 A has a cross-sectional area of 90 mm ² . The thermal emissivity of Cu is 0.03. _{Therefore, the amount of heat transfer QSB (Rigid)} due to heat radiation of a rigid bus bar using Cu is expressed as follows.

On the other hand, the cross-sectional area of the laminated bus bar 10 having an allowable current of 300 A is 38.4 mm ² . The metal flat plate 120 is Cu (heat emissivity: 0.03), the organic resin films 110-1 and 110-2 are PCT (heat emissivity: 0.95), and the adhesive 130 is epoxy (heat emissivity: 0). .84) is used, and the ratio of each to the cross-sectional area is 30% for Cu, 50% for PCT, and 20% for epoxy. _{Therefore, the amount of heat transfer QSB (Laminated)} due to heat radiation of the laminated bus bar 10 is expressed as follows.

As _{can be seen from the comparison between Q SB (Rigid)} and Q _{SB (Laminated)} , the laminated bus bar 10 has about 10 times the heat transfer amount as that of the rigid bus bar. That is, it can be seen that the laminated bus bar 10 has a much higher heat dissipation effect than the rigid bus bar.

Further, in the case of the laminated bus bar 10, the typical film thicknesses of the organic resin films 110-1 and 110-2 and the adhesive 130 are as small as 0.02 to 0.04 mm, while that of one metal flat plate 120. The typical width is as large as 1.6 mm. Therefore, even if the heat conductivity of the organic resin films 110-1 and 110-2 is small, once the heat conduction from the metal flat plate 120 occurs, the heat of the organic resin films 110-1 and 110-2 is increased due to the high thermal emissivity. Instead of accumulating inside 1 and 110-2, they will be released to the outside. Therefore, the temperature of the laminated bus bar 10 does not easily rise.

As can be seen from the above, from the viewpoint of heat loss, it is important that the laminated bus bar 10 according to the embodiment of the present invention has a structure in which the metal flat plate 120 is surrounded by a material having a high heat emissivity. Simply sandwiching the metal flat plate 120 between the organic resin films 110-1 and 110-2 causes air to enter and be trapped between them. Since the trapped air has a low heat emissivity of 0.024, the efficiency of heat dissipation to the outside by heat radiation is reduced. Therefore, in the laminated bus bar 10, in order to prevent the intrusion of air, the metal flat plate 120 is surrounded by the adhesive 130 having a high heat emissivity, and the metal flat plate 120 and the organic resin films 110-1 and 110-2 are adhered to each other. Adhere via agent 130.

Here, in the laminated bus bar 10, the effects of the presence or absence of the organic resin films 110-1 and 110-2 and the adhesive 130 were verified by using a simulation.

3A and 3B are side views and cross-sectional views showing a configuration for simulation of the laminated bus bar 10 according to the embodiment of the present invention. On the other hand, FIGS. 4A and 4B are side views and cross-sectional views showing a configuration for simulation of a bus bar that does not include the organic resin films 110-1 and 110-2 and the adhesive 130 as comparative examples.

In this simulation, the structure of the laminated bus bar 10 was further simplified, and the calculation was made as an engineering plastic 140 in which the organic resin films 110-1 and 110-2 and the adhesive 130 were integrated. The engineering plastic 140 refers to a group of plastics having high heat resistance.

Further, in each case, Cu was used as the material of the metal flat plate 120, and the width w of the metal flat plate 120 was 1.6 mm and the thickness t was 0.2 mm. The pitch d between the metal flat plates 120 was set to 1 mm. The length L of one FFC 10 was set to 500 mm, and the number of metal flat plates 120 contained in one FFC 10 was set to m = 5. Further, the number of FFC layers was set to n = 40. As a result, the total cross-sectional area of the metal flat plate 120 was 64 (= 1.6 × 0.2 × 5 × 40) mm ² .

The simulation conditions were that the measurement start temperature was 25 degrees and the amount of temperature rise at an applied current of 300 A was calculated.

The results of the simulation are shown in Table 1. The amount of temperature increase in the laminated bus bar 10 shown in FIGS. 3A and 3B was smaller than that in the bus bar shown in FIGS. 4A and 4B. This indicates that the laminated bus bar 10 has a structure that easily dissipates heat.

It was confirmed in the simulation that the laminated bus bar 10 according to the embodiment of the present invention has a structure that easily dissipates heat. This is due to the high thermal emissivity of the adhesive 130 and the organic resin films 110-1 and 110-2 that surround and contact the metal flat plate 120. When the temperature of the metal flat plate 120 rises, the resistance of the metal flat plate 120 increases, and it becomes difficult for current to flow. As a result, it is necessary to pass an electric current, and this electric current generates more heat. The laminated bus bar 10 does not require an additional current because it has a configuration that suppresses a temperature rise. Therefore, it can be said that the laminated bus bar 10 has a configuration capable of reducing heat loss.

[3. Current loss]
Next, the current loss of the laminated bus bar 10 will be examined. Although the power of the laminated bus bar 10 is represented by the above-described (Equation 1), considering that the power loss _{P loss} is 100 × r% of the applied power _{P appli,} the effective power _{P real} as shown in Equation (6) Can be represented.

Here, the effective power _Real can also be expressed as (Equation 7) by using the current I and the resistor R.

As can be seen from (Equation 7), the effective power _Real is proportional to the square I ^{2 of the} current and also proportional to the resistance R. Therefore, it can be seen that the current I should be increased in order to increase the _{effective power real.}

On the other hand, the power loss _loss is expressed as (Equation 8) by using the current I and the resistor R.

As the current I increases, the effective power _real increases, but as can be seen from (Equation 8), the power loss _loss also increases. Therefore, in the laminated bus bar 10, it is necessary to consider the maximum current I in which _{the power loss loss is suppressed.} It can also be said that the maximum current I in which the current loss of the laminated bus bar 10 is reduced is considered.

(Equation 8) is ^{expressed by the product of the square I 2 of the} current and the resistance R. Here, the power loss _loss ^{is the square I 2} component of the current and the resistance R component using the parameter x. It is assumed that it can be separated into. The square I ^{2 of the} current and the resistor R are expressed as (Equation 9) and (Equation 10) using the parameter x, respectively.

FIG. 5 ^{shows a graph of the square I 2} (x) of the current and the resistance R (x) with respect to the parameter x, which show the _{power loss loss.} The square I ^{2 of the} current and the resistance R are determined by the parameter x, but as can be seen from the graph shown in FIG. 5, ^{the curve of the square I 2} (x) of the current and the straight line of the resistance R (x) are interchanged. point _{a 0} is present. Point _{A 0} smaller area S and the point _{A 0} larger area S 'are both regions effective power _{P real} is larger than the power loss _{P loss.} However, the factors of _{current loss loss are different.} In the region S, the resistor R (x) is larger than the ^{current squared I 2 (x).} That is, in the region S, it can be said that the resistance component is dominant in _{the power loss loss.} On the other hand, in the _{region S'greater than the point A 0} , the square I ² (x) of the current is larger than the resistor R (x). That is, in the region S', it can be said that the current component is dominant in _{the power loss loss.} In other words, in the _{region larger than point A 0} , it can be said that the region has a large current loss. Therefore, in the laminated bus bar 10, the current loss can be reduced by using the value of the current I in the region S.

The value of x points A ₀ can be obtained as follows.

In (Equation 11), the current flowing through the laminated bus bar 10 is x = 0 when the DC current is 0, but x ≠ 0 when the DC current is AC current. Therefore, in the case of alternating current, the solution satisfying (Equation 11) is as shown in (Equation 12).

_{Since c 1} and c ₂ in (Equation 12) are constants, they are considered in the constant C of (Equation 8). Therefore, the value of x _{0 at point A 0} is represented by (Equation 13).

Here, an experimental measurement is performed between the rigid bus bar and the laminated bus bar 10, and the difference in characteristics between the rigid bus bar and the laminated bus bar 10 is expressed as a difference in physical quantity. In the region S, _{in order to reduce the loss} , the resistance component may be lowered. The magnitude of the resistance is inversely proportional to the cross-sectional area and proportional to the length. Therefore, as a physical quantity of x _0, for example, it can be used cross-sectional area or length. Here, it is possible to use the cross-sectional area as physical quantities x _0, the difference in characteristics between the laminated bus bar 10 and the rigid busbar, the total cross-sectional area of the flat metal plate 120 of the cross-sectional area as the stack bus bar 10 of metal rods rigid busbar Can be expressed using.

For example, when the amount of temperature rise is within a specific range and the cross-sectional area of the metal bar of the rigid bus bar capable of passing a current of 300 A is 90 mm ² , the metal flat plate 120 of the laminated bus bar 10 under the same conditions. The total cross-sectional area was measured experimentally as ^{38.4 mm 2.}

In order to reduce the current loss of the laminated bus bar 10, the value of the parameter x smaller than _{x 0 of (Equation 13) may be selected.} Therefore, considering that a ₁ , b ₁ , and b _{2 are variables in (Equation 13), a 1} and b ₁ are the squared I ² components of the current from (Equation 9), and (Equation 10). It can be seen from this that b ₂ is the resistance R component. In the case of alternating current, the difference between the laminated bus bar 10 and the rigid bus bar appears more prominently in the ^{square I 2 component of the current than in the resistance R component.} Therefore, here, the resistance R component is considered to be equivalent to the rigid bus bar, and b ₂ is replaced by the physical quantity of the rigid bus bar. Therefore, the above-mentioned measured value can be substituted into (Equation 13), and the value of x _{0 at point A 0} can be obtained as follows.

If the laminated bus bar 10 under the above conditions (the amount of temperature rise is within a specific range and a current of 300 A can be passed) is set to the total cross-sectional area of the metal flat plate 120 such that x ≦ 1.34. , The laminated bus bar 10 with reduced current loss can be obtained.

When the value of the current supplied to the laminated bus bar 10 is different, the value of the current supplied by the FFC 100 per layer may be obtained, and the number of layers n of the FFC 100 may be adjusted so as to be the set current value.

[4. Laminated bus bar design method]
As described above, the laminated bus bar 10 can reduce heat loss and current loss. Hereinafter, a method for designing the laminated bus bar 10 in which the heat loss and the current loss are reduced will be described. However, the design method of the laminated bus bar 10 is not limited to the following method.

In order to reduce heat loss, it is important to design the structure of the laminated bus bar 10, select the materials of the organic resin films 110-1 and 110-2, and the adhesive 130. Specifically, the laminated bus bar 10 is laminated with n layers of FFC 100. In the FFC 100, m metal flat plates 120 are arranged between the organic resin films 110-1 and 110-2 having high thermal emissivity. The metal flat plate 120 is adhered to the organic resin films 110-1 and 110-2 via an adhesive 130 having a high thermal emissivity, and the adhesive 130 is arranged so as to surround the metal flat plate 120. Further, the metal flat plate 120 is arranged so that the long side of the metal flat plate 120 is in a direction parallel to the organic resin films 110-1 and 110-2, and the metal flat plate 120 and the organic resin films 110-1 and 110-2 are arranged. Make sure that the area on which is superimposed is large. By designing the laminated bus bar 10 with the above-mentioned structure and material, heat loss can be reduced.

On the other hand, in order to reduce the current loss, it is important to design the structure of the metal flat plate 120 and select the material. The metal flat plate 120 is a metal flat plate 120 having high conductivity in order to reduce the resistance. Further, in the design of the structure of the metal flat plate 120, the physical quantity of the metal flat plate 120 corresponding to the physical quantity of the metal bar of the rigid bus bar under a specific condition is acquired by experimental measurement. As specific conditions, a specific value (value at point A) is obtained from the current value (for example, 300 A), the amount of temperature rise (for example, 100), the physical quantity of the metal rod of the rigid bus bar, and the physical quantity of the metal flat plate 120. The structure of the metal flat plate 120 is designed so that the physical quantity of the metal flat plate 120 is equal to or less than a specific value. As the physical quantity, for example, a cross-sectional area can be used. By designing the laminated bus bar 10 with the structure and material of the metal flat plate 120 described above, it is possible to reduce the current loss.

As described above, the laminated bus bar 10 has a structure in which a plurality of metal flat plates 120 are arranged between the organic resin films 110-1 and 110-2, and a plurality of FFC 100s fixed by an adhesive 130 are laminated. Since the organic resin films 110-1 and 110-2 and the adhesive 130 have high heat emissivity, heat is easily dissipated and heat loss is reduced. Further, by comparing the physical quantities of the laminated bus bar 10 and the rigid bus bar, it is possible to design the laminated bus bar 10 in which m metal flat plates 120 having reduced current loss and n layers of FFC 100 are laminated.

<Second Embodiment>
A laminated bus bar 10A different from the laminated bus bar 10 according to the first embodiment will be described with reference to FIG.

FIG. 6 is a schematic side view of the laminated bus bar 10A according to the embodiment of the present invention. The laminated bus bar 10A includes two types of FFC 100a and 100b. Further, as shown in FIG. 6, the two types of FFC100a and 100b are alternately laminated in the Z direction with FFC100a-1, 100b-1, 100a-2, ..., 100an, 100bn. ing. That is, the laminated bus bar 10A of FIG. 6 includes an n-layer FFC100a and an n-layer FFC100b.

The FFC 100a includes a plurality of metal flat plates 120a between the two organic resin films 110-1 and 110-2. That, FFC100a is the Y direction, a plurality of flat metal plate 120a-1,120a-2, ···, and _{120a-m a, m a} number of flat metal plate 120a is arranged. Further, the FFC 100b includes a plurality of metal flat plates 120b between the two organic resin films 110-1 and 110-2. That, FFC100b is the Y direction, a plurality of flat metal plate 120b-1,120b-2, ···, and _{120b-m b, m b} pieces of flat metal plate 120a is arranged.

In the laminated bus bar 10A shown in FIG. 6, the metal flat plate 120a of the FFC100a and the metal flat plate 120b of the FFC100b do not overlap in the Z direction. That is, a _{m a} number of flat metal plate 120a included in one FFC100a, the _{m b} pieces of flat metal plate 120b contained in one _FFC100b, a relationship of m a _{= m} b +1. However, the number of the metal flat plate 120a and the metal flat plate 120b is not limited to this. The number of the metal flat plate 120a and the metal flat plate 120b may be, for _example, the relationship m _a = _2m b +1. This means that two metal flat plates 120b are provided in the FFC 100b so as to overlap with the region between the adjacent metal flat plates 120a in the FFC 100a.

Further, as a modification of the laminated bus bar 10A, in the laminated bus bar 10A, the metal flat plate 120a of the FFC 100a and the metal flat plate 120b of the FFC 100b can be partially overlapped in the Z direction. That is, the end portion of the metal flat plate 120a and the end portion of the metal flat plate 120b may overlap.

Further, as another modification of the laminated bus bar 10A, it is possible to configure the pitch between the adjacent metal flat plates 120a in the FFC 100a and the pitch between the adjacent metal flat plates 120b in the FFC 100b to be different. In this case, in the Z direction, the metal flat plate 120a of the FFC 100a and the metal flat plate 120b of the FFC 100b do not completely overlap, but a part of the metal flat plate 120b can be overlapped. Further, the width of the metal flat plate 120a in the FFC 100a and the width of the metal flat plate 120b in the FFC 100b may be different from each other. Also in this case, in the Z direction, the metal flat plate 120a of the FFC 100a and the metal flat plate 120b of the FFC 100b do not completely overlap, and a part of the metal flat plate 120b can be overlapped.

As described above, the laminated bus bar 10A has a structure in which FFCs having different arrangements, pitches, or widths of metal flat plates are alternately laminated, including a modification. By shifting the superposition of the metal flat plates in the FFC stacking direction (Z direction), the influence between the metal flat plates can be eliminated. For example, when a high-frequency alternating current is passed through a metal flat plate, the alternating current flowing through the metal flat plate forms a magnetic field, and the magnetic field generates an eddy current. In the laminated bus bar 10A, since the superposition of the metal flat plates is shifted, the other is less susceptible to the influence of the magnetic field formed on one of the adjacent metal flat plates. Therefore, in the laminated bus bar 10A, the eddy current of the metal flat plate can be reduced. Therefore, the laminated bus bar 10A not only reduces the heat loss, but also reduces the current loss.

<Third Embodiment>
The battery module 20 to which the laminated bus bar 10 according to the first embodiment is applied will be described with reference to FIG. 7.

FIG. 7 is a schematic perspective view of the battery module 20 according to the embodiment of the present invention. The battery module 20 includes a first battery unit 200-1, a second battery unit 200-2, a third battery unit 200-3, and a fourth battery unit 200-4. In the following, unless the first battery unit 200-1, the second battery unit 200-2, the third battery unit 200-3, and the fourth battery unit 200-4 are particularly distinguished, they are described as the battery unit 200. I will explain.

The battery unit 200 includes a plurality of battery cells 210. Further, each of the plurality of battery cells 210 includes a + electrode 220-1 and a-electrode 220-2. Two adjacent battery cells 210 in one battery unit 200 are connected in series by the first laminated bus bar 10-1 so that the + electrode 220-1 and the-electrode 220-2 are electrically connected. There is.

Further, the first battery cell 210-1 and the second battery cell 210-2, and the third battery cell 210-3 and the fourth battery cell 210-4 are electrically connected by the second laminated bus bar 10-2. ing. Further, the second battery cell 210-2 and the third battery cell 210-3 are electrically connected by the third laminated bus bar 10-3.

The length of the first laminated bus bar 10-1, the second laminated bus bar 10-2, and the third laminated bus bar 10-3 can be changed depending on the connecting position. Further, the number of laminated FFC 100s included in the laminated bus bar 10 may be changed, and the number of metal flat plates 120 included in the FFC 100 may be changed.

Further, the first laminated bus bar 10-1, the second laminated bus bar 10-2, and the third laminated bus bar 10-3 shown in FIG. 7 are drawn linearly for convenience, but the laminated bus bar 10 has flexibility. , Can be provided in a curved line. Therefore, it is possible to process the laminated bus bar 10 into various shapes and electrically connect between a plurality of battery units 200 or between a plurality of battery cells 210. Therefore, it is possible to electrically connect between a plurality of battery units 200 or between a plurality of battery cells 210 by utilizing a small space in the battery pack accommodating the battery module 20.

As described above, by using the laminated bus bar 10 in the battery module 20, it is possible to electrically connect even in a narrow space. Further, by increasing the degree of freedom of electrical connection of the battery unit 200 or the battery cell 210, the degree of freedom of arrangement of the battery unit 200 or the battery cell 210 is also increased. Further, since the laminated bus bar 10 has a high heat dissipation effect, the heat generated in the battery cell 210 can be dissipated through the laminated bus bar 10.

The battery module 20 can be used, for example, in an electric vehicle (EV: Electric Vehicle), a hybrid vehicle (HEV: Hybrid Electric Vehicle), or a plug-in hybrid vehicle (PHEV: Plug-in Hybrid Electric Vehicle). Since the laminated bus bar 10 of the battery module 20 is lightweight, the cruising range of the electric vehicle, the hybrid vehicle, or the plug-in hybrid vehicle using the battery module 20 becomes long.

Each embodiment of the present invention can be implemented in appropriate combinations as long as they do not contradict each other. Further, based on the laminated bus bar of each embodiment, those skilled in the art with appropriate additions, deletions, or modifications of components are also included in the scope of the present invention as long as the gist of the present invention is provided.

In addition, even if the action and effect are different from the action and effect brought about by each embodiment of the present invention, those that are clear from the description of the present specification or those that can be easily predicted by those skilled in the art are of course. Is understood to be brought about by the present invention.

10, 10A: Laminated bus bar, 10-1: 1st laminated bus bar, 10-2: 2nd laminated bus bar, 10-3: 3rd laminated bus bar, 11: Main body, 12: Terminal, 20: Battery module, 100 , 100a, 100b: Flexible flat cable (FFC), 110-1, 110-2: Organic resin film, 120, 120a, 120b: Metal flat plate, 121: Metal clad part, 130: Adhesive, 140: Engineering plastic, 200 : Battery unit, 200-1: 1st battery unit, 200-2: 2nd battery unit, 200-3: 3rd battery unit, 210: Battery cell, 210-1: 1st battery cell, 210-2: 1st 2 battery cells, 210-3: 3rd battery cell, 210-4: 4th battery cell, 220-1: + electrode, 220-2: -electrode

Claims (15)

A laminated bus bar in which multiple flexible flat cables (FFCs) are laminated.
Each of the plurality of flexible flat cables (FFC)
Two organic resin films and
A plurality of metal flat plates between the two organic resin films and
Includes an adhesive that adheres the two organic resin films and the plurality of metal flat plates.
The adhesive is provided between the adjacent metal flat plates, and the adhesive is provided.
A laminated bus bar in which the thermal emissivity of each of the two organic resin films and the adhesive is higher than the thermal emissivity of the metal flat plate. A laminated bus bar in which multiple flexible flat cables (FFCs) are laminated.
Each of the plurality of flexible flat cables (FFC)
Two organic resin films and
A plurality of metal flat plates between the two organic resin films and
Includes an adhesive that adheres the two organic resin films and the plurality of metal flat plates.
The adhesive is provided between the adjacent metal flat plates, and the adhesive is provided.
Of the plurality of flexible flat cables (FFCs), two adjacent flexible flat cables (FFCs) differ in the number of the plurality of metal flat plates contained therein.
A laminated bus bar in which the thermal emissivity of each of the two organic resin films and the adhesive is higher than the thermal emissivity of the metal flat plate. The laminated bus bar according to claim 1 or 2, wherein the heat emissivity of the two organic resin films is 0.8 or more. The laminated bus bar according to any one of claims 1 to 3, wherein the material of the two organic resin films is polycyclohexanedimethylene terephthalate (PCT). The laminated bus bar according to any one of claims 1 to 4, wherein the material of the adhesive is polyester. The metal flat plate is rectangular and has a rectangular shape.
The laminated bus bar according to any one of claims 1 to 5, wherein the length of the long side of the rectangle is five times or more the length of the short side of the rectangle. Obtained by using the physical quantity of the metal bar obtained under predetermined conditions of a rigid bus bar using the material of the metal flat plate as the metal bar, and the physical quantity of the metal flat plate corresponding to the physical quantity of the metal bar. The laminated bus bar according to any one of claims 1 to 6, wherein the structure of the metal flat plate is determined by using the physical quantity of the metal flat plate as a parameter so that the value is equal to or less than a specific value. Physical quantity of said metallic bar is a cross-sectional area A ₁ of the metal bar,
Physical quantity of the flat metal is the total cross-sectional area A ₂ of said plurality of flat metal contained in the stacked plurality of flexible flat cable (FFC),
The laminated bus bar according to claim 7, wherein the total cross-sectional area A _{2 of the plurality of metal flat plates satisfies the following formula.}

The laminated bus bar according to claim 8, wherein the cross-sectional area A ₁ of the metal rod is 90 mm ^2. 1st battery cell and
With the second battery cell
Includes a laminated bus bar in which the electrodes of the first battery cell and the electrodes of the second battery cell are electrically connected and a plurality of flexible flat cables (FFCs) are laminated.
Each of the plurality of flexible flat cables (FFC)
Two organic resin films and
A plurality of metal flat plates between the two organic resin films and
Includes an adhesive that adheres the two organic resin films and the plurality of metal flat plates.
The adhesive is provided between the adjacent metal flat plates, and the adhesive is provided.
A battery module in which the thermal emissivity of each of the two organic resin films and the adhesive is higher than the thermal emissivity of the metal flat plate. The first battery cell is included in the first battery unit.
The battery module according to claim 10, wherein the second battery cell is included in a second battery unit different from the first battery unit. The battery module according to claim 10 or 11, which is used in an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. A flexible flat cable (FFC) including two organic resin films, a plurality of metal flat plates between the two organic resin films, and an adhesive for adhering the two organic resin films and the plurality of metal flat plates. Is a method of designing a laminated bus bar in which multiple layers are laminated.
Obtaining the physical quantity of the metal rod under predetermined conditions of a rigid bus bar using the material of the metal flat plate as the metal rod,
Obtaining the physical quantity of the metal flat plate under the predetermined conditions of the laminated bus bar,
A specific value is calculated using the physical quantity of the metal rod and the physical quantity of the metal flat plate.
A method for designing a laminated bus bar that determines the structure of the metal flat plate with the physical quantity of the metal flat plate as a parameter so as to be equal to or less than the specific value. Physical quantity of said metallic bar is a cross-sectional area A ₁ of the metal bar,
The physical quantity of the metal flat plates is the total cross-sectional area A ₂ of the plurality of metal plates included in the flexible flat cables (FFCs) laminated.
The method for designing a laminated bus bar according to claim 13, wherein the structure of the metal flat plate is determined so as to satisfy the following equation with the total cross-sectional area A _{2 of the plurality of metal flat plates as a parameter.}

The method for designing a laminated bus bar according to claim 14, wherein the cross-sectional area A ₁ of the metal rod is 90 mm ^2.

Images