Patent Description:
The present technology relates to a battery module.

A battery module in which a plurality of battery cells are stacked has been conventionally known. The plurality of battery cells are restrained in the stacking direction by restraint members. As a mechanism for adjusting a restraint force in the stacking direction, there have been known mechanisms described in <CIT> and <CIT>.

Further, patent document <CIT> discloses a battery module including: a plurality of unit battery cells; a pair of end plates which are arranged at both ends of the plurality of the laminated unit battery cells, and spatially separated from each other and fastened together in order to house the plurality of the unit battery cells; and a pressure adjustment part which is arranged between the unit battery cells and at least one of the end plates and adjusts pressure applied to the plurality of the unit battery cells.

Patent document <CIT> discloses a battery clamping device including: an interposition member configured to be interposed between rectangular parallelepiped batteries such that the interposition member is stacked with a plurality of the batteries alternately; a clamping portion configured to clamp by pressing the stacked batteries and the interposition member in a stacking direction of the batteries and the interposition member from outside in the stacking direction.

Moreover, patent document <CIT> discloses a power storage device which is provided with a cell stack body formed by alternately arranging a plurality of secondary cells and a plurality of buffer plates. Each of the buffer plates has a non-deformable section and a deformable section that is elastically deformed according to a volume change in the secondary cell. The non-deformable section has a through hole in which the deformable section is fitted. The deformable section is formed thicker than the non-deformable section.

In addition, patent document <CIT> discloses an electrical energy storage device including a cell stack with a plurality of layers of battery cells disposed one above the other and disposed between a first pressure plate and a second pressure plate. A distance between the first pressure plate and the second pressure plate is changeable by actuation of an actuator unit. The actuator unit has a flexible envelope element which encloses the first pressure plate, the second pressure plate, and the cell stack and has a rolling element. The flexible envelope element is rollable up and unrollable by the rolling element such that the distance between the first pressure plate and the second pressure plate is changeable by a change in a length of the flexible envelope element in a peripheral direction of the flexible envelope element.

Each of the adjustment mechanisms described in <CIT> and <CIT> is intended to suppress a restraint force for the battery cells from being increased to fall within an unintended range when an ambient temperature or a temperature of the battery module is increased. In order to adjust the restraint force in response to a customer's request or the like after restraining the battery cells by the restraint members, a different mechanism is required. An object of the present technology is to provide a battery module in which a restraint load for battery cells by a restraint mechanism can be readily adjusted.

The above-mentioned object is solved by the subject-matter of claim <NUM>. Further advantageous configurations of the invention can be drawn from the dependent claims.

A battery module according to an explanatory aspect of the present technology includes: a plurality of battery cells arranged side by side in a first direction, each of the plurality of battery cells having a prismatic shape; a restraint mechanism that restrains the plurality of battery cells in the first direction; and a restraint force adjustment mechanism capable of adjusting a restraint load in the first direction, the restraint load being applied by the restraint mechanism. The restraint force adjustment mechanism includes an operation portion to be operated when adjusting the restraint load. The operation portion is provided on the battery module.

Hereinafter, embodiments of the present technology will be described. It should be noted that the same or corresponding portions are denoted by the same reference characters, and may not be described repeatedly.

It should be noted that in the embodiments described below, when reference is made to number, amount, and the like, the scope of the present technology is not necessarily limited to the number, amount, and the like unless otherwise stated particularly. Further, in the embodiments described below, each component is not necessarily essential to the present technology unless otherwise stated particularly.

It should be noted that in the present specification, the terms "comprise", "include", and "have" are open-end terms. That is, when a certain configuration is included, a configuration other than the foregoing configuration may or may not be included. Further, the present technology is not limited to one that necessarily exhibits all the functions and effects stated in the present embodiment.

In the present specification, the term "battery" is not limited to a lithium ion battery, and may include another battery such as a nickel-metal hydride battery. In the present specification, the term "electrode" may collectively represent a positive electrode and a negative electrode. Further, the term "electrode plate" may collectively represent a positive electrode plate and a negative electrode plate.

It should be noted that in the figures, a stacking direction of the battery cells is defined as a first direction serving as a Y direction, a direction in which two electrode terminals of each battery cell are arranged side by side is defined as a second direction serving as an X direction, and a height direction of the battery cell is defined as a third direction serving as a Z direction.

<FIG> is a perspective view showing a configuration of a battery module according to one embodiment of the present technology. <FIG> is a perspective view of the battery module of <FIG> when viewed in a direction of an arrow II. <FIG> is a perspective view showing configurations of a unit and end plates included in the battery module according to the embodiment of the present technology.

A battery module <NUM> is used as a power supply for driving a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV), for example.

First, an overall structure of battery module <NUM> will be described. As shown in <FIG>, battery module <NUM> includes a plurality of units <NUM>, end plates <NUM>, restraint members <NUM>, a lower restraint member <NUM>, a wiring member <NUM>, a duct <NUM>, and connection terminals <NUM>.

The plurality of units <NUM> are arranged side by side in the first direction (Y direction). Six units <NUM> are arranged side by side in the Y direction as the plurality of units <NUM> according to the present embodiment. It should be noted that the number of the plurality of units <NUM> is not particularly limited as long as two or more units <NUM> are included.

The plurality of units <NUM> are sandwiched between two end plates <NUM>. The plurality of units <NUM> according to the present embodiment are pressed by end plates <NUM> and restrained between two end plates <NUM>.

End plates <NUM> are provided at the both ends beside the plurality of units <NUM> in the Y direction. Each of end plates <NUM> is fixed to a base such as a pack case that accommodates battery module <NUM>. End plate <NUM> is composed of, for example, aluminum or iron.

Restraint members <NUM> are provided on both sides beside the plurality of units <NUM> and end plates <NUM> in the X direction. When restraint members <NUM> are engaged with end plates <NUM> with compressive force in the Y direction being applied to the plurality of units <NUM> arranged side by side and to end plates <NUM> and then the compressive force is released, tensile force acts on restraint members <NUM> that connect two end plates <NUM>. As a reaction thereto, restraint members <NUM> press two end plates <NUM> in directions of bringing them closer to each other. As a result, restraint members <NUM> restrain the plurality of units <NUM> in the first direction (the Y direction).

Each of restraint members <NUM> includes a plate-shaped portion <NUM>, a first flange portion <NUM>, and second flange portions <NUM>. Restraint member <NUM> is composed of iron, for example.

Plate-shaped portion <NUM> is a member extending in the Y direction. Plate-shaped portion <NUM> is provided with a plurality of openings <NUM>. The plurality of openings <NUM> are provided at intervals in the Y direction, and each of openings <NUM> is constituted of a through hole extending through plate-shaped portion <NUM> in the X direction.

First flange portion <NUM> extends from beside the side surfaces of the plurality of units <NUM> so as to be located over the upper surfaces of the plurality of units <NUM>. By providing first flange portion <NUM>, rigidity of restraint member <NUM> formed to be relatively thin can be secured.

Second flange portions <NUM> are connected to both ends of plate-shaped portion <NUM> in the Y direction. Second flange portions <NUM> are fixed to end plates <NUM>. Bolt holes 530A are formed in second flange portions <NUM>. Restraint members <NUM> are fixed to end plates <NUM> by bolts 500A inserted in bolt holes 530A, for example. Thus, restraint members <NUM> connect two end plates <NUM> to each other.

As shown in <FIG>, lower restraint member <NUM> is provided on the bottom surfaces of the plurality of units <NUM> and end plates <NUM>. Lower restraint member <NUM> protects below-described battery cells <NUM> from the bottom surface side. Lower restraint member <NUM> is composed of iron, for example.

As shown in <FIG>, wiring member <NUM> is provided at a position facing the plurality of units <NUM> in the Z direction. Wiring member <NUM> extends in the Y direction through the center portion of each of the plurality of units <NUM> in the X direction. Wiring member <NUM> is electrically connected to the plurality of units <NUM>. Wiring member <NUM> is, for example, a flexible printed circuit board.

Duct <NUM> extends in the Y direction. Duct <NUM> extends at a position overlapping with wiring member <NUM> when viewed in the Z direction. Duct <NUM> is disposed between each of the plurality of units <NUM> and wiring member <NUM> in the Z direction.

Connection terminals <NUM> are arranged on both sides beside the plurality of units <NUM> arranged side by side in the Y direction. Each of connection terminals <NUM> is provided at a position overlapping with end plate <NUM> when viewed in the Z direction. Connection terminal <NUM> connects battery module <NUM> to an external wiring such as a cable (not shown) disposed outside battery module <NUM>.

A restraint force adjustment mechanism <NUM> is provided on an end surface of end plate <NUM>. Restraint force adjustment mechanism <NUM> includes: a bolt member <NUM> attached to end plate <NUM>; a nut member <NUM> screwed on bolt member <NUM>; and a shim member <NUM>.

Next, a structure of unit <NUM> will be described. <FIG> is a perspective view showing a configuration of the unit included in the battery module according to the embodiment of the present technology. <FIG> is a perspective view of the unit of <FIG> when viewed in a direction of an arrow V.

As shown in <FIG>, each of the plurality of units <NUM> includes a plurality of battery cells <NUM>, a case <NUM> serving as a supporting member, and a bus bar <NUM>.

Unit <NUM> includes two or more battery cells <NUM>. Unit <NUM> according to one embodiment of the present technology includes four battery cells <NUM> as an even number of battery cells <NUM>. It should be noted that the number of battery cells <NUM> included in each of the plurality of units <NUM> is not particularly limited as long as two or more battery cells <NUM> are included. Moreover, an odd number of battery cells <NUM> may be included in each of the plurality of units <NUM>.

The plurality of battery cells <NUM> are arranged side by side in the first direction (Y direction). Four battery cells <NUM> are arranged side by side in the Y direction as the plurality of battery cells <NUM> according to the embodiment of the present technology. The arrangement direction of the plurality of units <NUM> is the same as the arrangement direction of the plurality of battery cells <NUM> in each of the plurality of units <NUM>.

Case <NUM> has an external appearance with a rectangular parallelepiped shape. Case <NUM> accommodates the plurality of battery cells <NUM>. Case <NUM> is composed of, for example, a resin such as polypropylene. As shown in <FIG>, case <NUM> is compressed in the first direction (Y direction) by restraint members <NUM>.

A bolt hole 400A for attaching bolt member <NUM> of restraint force adjustment mechanism <NUM> is formed in end plate <NUM>.

As shown in <FIG>, case <NUM> has a front wall portion <NUM>, a rear wall portion <NUM>, a first side wall portion <NUM>, a second side wall portion <NUM>, and an upper surface portion <NUM>.

Front wall portion <NUM> is a surface adjacent to one of restraint members <NUM>. As shown in <FIG>, front wall portion <NUM> is provided with a plurality of first ventilation ports <NUM>. Each of first ventilation ports <NUM> is a through hole extending through front wall portion <NUM> in the X direction.

As shown in <FIG>, rear wall portion <NUM> is a surface facing front wall portion <NUM> with the plurality of battery cells <NUM> being interposed therebetween in the X direction. Rear wall portion <NUM> is provided with a plurality of second ventilation ports <NUM>. Each of second ventilation ports <NUM> is a through hole extending through rear wall portion <NUM> in the X direction.

First side wall portion <NUM> and second side wall portion <NUM> are arranged side by side in the first direction (Y direction), and face each other.

As shown in <FIG>, first side wall portion <NUM> has a protrusion <NUM>. Protrusion <NUM> protrudes opposite to second side wall portion <NUM>. As shown in <FIG>, second side wall portion <NUM> is provided with a recess <NUM>. Recess <NUM> is recessed toward first side wall portion <NUM> and has a shape engageable with protrusion <NUM>. Protrusion <NUM> and recess <NUM> of adjacent units <NUM> of the plurality of units <NUM> are engaged with each other.

Upper surface portion <NUM> includes first wall portions <NUM>, second wall portions <NUM>, third wall portions <NUM>, fourth wall portions <NUM>, engagement surfaces <NUM>, and hole portions <NUM>. Two first wall portions <NUM> are formed parallel to each other so as to extend in the Y axis direction at the center portion in the X direction. Second wall portions <NUM>, third wall portions <NUM>, and fourth wall portions <NUM> are provided on both sides beside first wall portions <NUM> in the X direction so as to define installation positions for bus bars <NUM>. Each of second wall portions <NUM> is provided with a notch 252A through which a below-described voltage detection wire <NUM> extends. Second flange portions <NUM> of restraint members <NUM> are engaged with engagement surfaces <NUM>. Hole portions <NUM> communicate with below-described gas-discharge valves <NUM>.

Each of bus bars <NUM> is composed of an electric conductor. The plurality of bus bars <NUM> electrically connect the plurality of battery cells <NUM> together.

<FIG> is a perspective view showing a configuration of a battery cell included in the battery module according to the embodiment of the present technology.

As shown in <FIG>, battery cell <NUM> is, for example, a lithium ion battery. Battery cell <NUM> has a prismatic shape.

Battery cell <NUM> according to the present embodiment has electrode terminals <NUM>, a housing <NUM>, and a gas-discharge valve <NUM>.

Electrode terminals <NUM> are formed on housing <NUM>. Electrode terminals <NUM> have a positive electrode terminal <NUM> and a negative electrode terminal <NUM> as two electrode terminals <NUM> arranged side by side along the second direction (the X direction) orthogonal to the first direction (the Y direction).

Positive electrode terminal <NUM> and negative electrode terminal <NUM> are provided to be separated from each other in the X direction. Positive electrode terminal <NUM> and negative electrode terminal <NUM> are provided on both sides beside wiring member <NUM> and duct <NUM> in the X direction.

Housing <NUM> has a rectangular parallelepiped shape, and forms the external appearance of battery cell <NUM>. An electrode assembly (not shown) and an electrolyte solution (not shown) are accommodated in housing <NUM>.

Housing <NUM> includes an upper surface <NUM>, a lower surface <NUM>, a first side surface <NUM>, a second side surface <NUM>, and a third side surface <NUM>.

Upper surface <NUM> is a flat surface orthogonal to the Z direction. Electrode terminals <NUM> are disposed on upper surface <NUM>. Lower surface <NUM> faces upper surface <NUM> along the third direction (Z direction) orthogonal to the first direction (Y direction).

Each of first side surface <NUM> and second side surface <NUM> is constituted of a flat surface orthogonal to the Y direction. Each of first side surface <NUM> and second side surface <NUM> has the largest area among the areas of the plurality of side surfaces of housing <NUM>. Each of first side surface <NUM> and second side surface <NUM> has a rectangular shape when viewed in the Y direction. Each of first side surface <NUM> and second side surface <NUM> has a rectangular shape in which the X direction corresponds to the long-side direction and the Z direction corresponds to the short-side direction when viewed in the Y direction.

The plurality of battery cells <NUM> are stacked such that first side surfaces <NUM> of battery cells <NUM>, <NUM> adjacent to each other in the Y direction face each other and second side surfaces <NUM> of battery cells <NUM>, <NUM> adjacent to each other in the Y direction face each other. Thus, positive electrode terminals <NUM> and negative electrode terminals <NUM> are alternately arranged in the Y direction in which the plurality of battery cells <NUM> are stacked.

It should be noted that when an odd number of battery cells <NUM> are included in unit <NUM>, the posture of unit <NUM> may be turned by <NUM>° with respect to the Z axis between units <NUM> adjacent to each other in the Y direction.

Gas-discharge valve <NUM> is provided in upper surface <NUM>. When internal pressure of housing <NUM> becomes more than or equal to a predetermined value due to gas generated inside housing <NUM>, gas-discharge valve <NUM> discharges the gas to the outside of housing <NUM>. The gas from gas-discharge valve <NUM> flows through duct <NUM> in <FIG> and is discharged to the outside of battery module <NUM>.

<FIG> is a partial perspective view showing a configuration of each voltage detection wire included in the battery module according to the embodiment of the present technology.

As shown in <FIG>, wiring member <NUM> includes voltage detection wires <NUM> that each detects a voltage. The plurality of voltage detection wires <NUM> extend to and are connected to bus bars <NUM>. One voltage detection wire <NUM> is disposed in each of the plurality of units <NUM>. Thus, voltage detection wire <NUM> can detect the voltage of unit <NUM>.

<FIG> is a diagram showing a structure of restraint force adjustment mechanism <NUM> according to an example. End plate <NUM> and restraint member <NUM> (binding bar) shown in <FIG> constitute a restraint mechanism that restrains the plurality of units <NUM> in the first direction (Y direction). Bolt member <NUM> is provided in end plate <NUM> in the same direction as the stacking direction (Y direction) of units <NUM>. A plurality of bolt members <NUM> may be provided. Bolt member <NUM> may also serve as a vehicle-side fastening point, and bolt member <NUM> is coupled to a vehicle-side fixation bracket in this case.

Nut member <NUM> is screwed on bolt member <NUM>. By fastening nut member <NUM> toward the right side in the figure, end plate <NUM> is deflected (chain double-dashed line in the figure) to protrude in a direction of an arrow DR1 (right side in the figure). As a result, a restraint force for units <NUM> is increased. Nut member <NUM> constitutes an operation portion to be operated when adjusting a restraint load.

An amount of deflection of end plate <NUM> can be adjusted by shim member <NUM>. Shim member <NUM> is provided between a unit <NUM> located at an end portion and end plate <NUM>. When bolt member <NUM> also serves as a vehicle-side fastening point (fixation member), shim member <NUM> is provided between end plate <NUM> and the vehicle-side (base-side) fixation bracket (attachment member).

In this way, in restraint force adjustment mechanism <NUM>, nut member <NUM> can be fastened onto bolt member <NUM> to deflect end plate <NUM> toward the stack of units <NUM>, and an amount of fastening of nut member <NUM> can be adjusted to adjust the amount of deflection of end plate <NUM>. Thus, the restraint force by end plate <NUM> can be adjusted.

<FIG> is a diagram showing a state when the adjustment mechanism shown in <FIG> is viewed in the Y direction. As shown in <FIG>, when battery cell <NUM> is projected onto end plate <NUM> along the Y direction, bolt hole 400A into which bolt member <NUM> is attached is provided in a region in which an electrode assembly <NUM> of battery cell <NUM> is located (more preferably, in a region of a range of application of a positive electrode active material layer included in electrode assembly <NUM>). Thus, bolt member <NUM> can be provided at least in a region that requires restraint.

<FIG> is a diagram showing a structure of a restraint force adjustment mechanism <NUM> according to a modification. Plate-shaped portion <NUM> of restraint member <NUM> is fastened to an intermediate plate <NUM> (another module component) along the X direction (or the Z direction) orthogonal to the stacking direction (Y direction) of units <NUM>. Specifically, bolt member <NUM> extends through plate-shaped portion <NUM>, and the tip of bolt member <NUM> is fixed to intermediate plate <NUM>.

When bolt member <NUM> is fastened toward intermediate plate <NUM>, plate-shaped portion <NUM> of restraint member <NUM> is deflected to protrude in a direction of an arrow DR2 (upper side in the figure). As a result, battery module <NUM> is deformed to be reduced in its length in the first direction (Y direction), thereby increasing the restraint force for units <NUM>.

When bolt member <NUM> is loosened and a shim member <NUM> is inserted between plate-shaped portion <NUM> of restraint member <NUM> and intermediate plate <NUM>, plate-shaped portion <NUM> is deflected to protrude in a direction of an arrow DR3 (lower side in the figure). Also in this case, battery module <NUM> is deformed to reduce its length in the stacking direction (Y direction), thereby increasing the restraint force for units <NUM>.

The amount of deflection of plate-shaped portion <NUM> of restraint member <NUM> can be adjusted by the amount of fastening of bolt member <NUM> and the thickness of shim member <NUM>. That is, by adjusting the fastening force of bolt member <NUM>, the amount of deflection of restraint member <NUM> along the X direction or the Z direction can be adjusted, thereby adjusting the length of battery module <NUM> along the Y direction. Here, bolt member <NUM> constitutes an operation portion to be operated when adjusting a restraint load.

In battery module <NUM> according to the embodiment of the present technology, since the operation portion to be operated when adjusting the restraint load is provided on battery module <NUM>, the restraint load can be readily adjusted after the battery cells are restrained by the restraint members. Therefore, the restraint load can be readily adjusted in response to a customer's request or the like at the time of shipment of a product or the like after forming battery module <NUM>.

Further, in battery module <NUM>, since the plurality of battery cells <NUM> are accommodated in case <NUM> such that they are arranged side by side in the first direction (Y direction), unit <NUM> is formed, and the plurality of such units <NUM> are arranged side by side in the first direction (Y direction) to form battery module <NUM>, the manufacturing process can be simplified as compared with a case where battery module <NUM> is manufactured with each of the plurality of battery cells <NUM> being handled as one unit. An example of the simplification is, for example, as follows: units <NUM> each formed to be small is caused to pass through a welding machine to weld bus bars <NUM> in units <NUM>, and then bus bars <NUM> over different units <NUM> are individually joined together, thereby attaining increased efficiency in the welding process.

Further, in battery module <NUM>, since units <NUM> each including the plurality of battery cells <NUM> accommodated in case <NUM> are formed, battery module <NUM> can be readily disassembled or replaced with each unit <NUM> being handled as one unit.

Further, in battery module <NUM>, since units <NUM> each including the plurality of battery cells <NUM> accommodated in case <NUM> are formed, battery module <NUM> can be divided with each unit <NUM> being handled as one unit when discarding battery module <NUM> so as to lower the voltage for the purpose of handling, thereby facilitating the discarding of battery module <NUM>.

Further, in battery module <NUM>, battery cells <NUM> can be restrained by restraint members <NUM> through the configurations of units <NUM>.

Further, in battery module <NUM>, the plurality of units <NUM> can be connected together by bus bars <NUM> to thereby manufacture battery module <NUM> with each of units <NUM> being handled as one unit.

Claim 1:
A battery module (<NUM>) comprising:
a plurality of battery cells (<NUM>) arranged side by side in a first direction, each of the plurality of battery cells (<NUM>) having a prismatic shape;
a restraint mechanism (<NUM>, <NUM>) that restrains the plurality of battery cells (<NUM>) in the first direction; and
a restraint force adjustment mechanism (<NUM>, <NUM>) capable of adjusting a restraint load in the first direction, the restraint load being applied by the restraint mechanism (<NUM>, <NUM>), wherein
the restraint force adjustment mechanism (<NUM>, <NUM>) includes an operation portion (<NUM>, <NUM>) to be operated when adjusting the restraint load (<NUM>, <NUM>),
the operation portion (<NUM>, <NUM>) is provided on the battery module (<NUM>),
the restraint mechanism (<NUM>, <NUM>) includes two end plates (<NUM>) provided at both end portions of a stack of the plurality of battery cells (<NUM>) in the first direction, and a binding bar (<NUM>) that connects the two end plates (<NUM>) to each other,
i) the restraint force adjustment mechanism (<NUM>) includes:
at least one bolt member (<NUM>) attached to one of the two end plates (<NUM>) along the first direction, and
a nut member (<NUM>) screwed on the bolt member (<NUM>), and
one of the two end plates (<NUM>) is able to be deflected toward the stack by fastening the nut member (<NUM>) onto the bolt member (<NUM>), and an amount of deflection of one of the two end plates (<NUM>) is able to be adjusted by adjusting an amount of fastening of the nut member (<NUM>),
or
ii) the restraint force adjustment mechanism (<NUM>) includes a bolt member (<NUM>) extending through the binding bar (<NUM>) along a second direction orthogonal to the first direction and fastened to another component of the battery module (<NUM>), and
by adjusting a fastening force of the bolt member (<NUM>), an amount of deflection of the binding bar (<NUM>) along the second direction is able to be adjusted to adjust a length of the battery module (<NUM>) along the first direction.