Patent Description:
The present disclosure relates to a battery pack.

Conventionally, a battery pack including a plurality of batteries housed in a case is known. The battery pack needs to dissipate heat generated by each of the plurality of batteries to an outside of the battery pack. For example, Patent Literature <NUM> discloses a temperature management system which includes thermally conductive members in contact with each of the plurality of batteries aligned in two rows, and dissipates heat of the batteries to an outside by a refrigerant flowing inside the thermally conductive members. Furthermore, Patent Literature <NUM> discloses a battery module which dissipates heat generated by cylindrical batteries to an outside by using a thermally conductive material filled between the plurality of cylindrical batteries. Patent Literature <NUM> (basis for the preamble of claim <NUM>) discloses another battery pack. Furthermore, Non-Patent Literature <NUM> discloses a heat management system in which both end parts of thermally conductive members in contact with each of a plurality of batteries are connected with a case, and which dissipates heat generated by the batteries to an outside.

However, the above prior arts still have a room for improvement to improve cooling efficiency of batteries of a battery pack while reducing manufacturing cost of the battery pack. According to, for example, a technique disclosed in Patent Literature <NUM>, the refrigerant which cools the batteries flows inside the thermally conductive members, and then flows in flow passages formed inside a case. Hence, the thermally conductive members and the case need to be connected so as not to cause leakage of a liquid. Hence, the thermally conductive members need to be precisely manufactured, and manufacturing cost is high. Furthermore, according to a technique disclosed in Patent Literature <NUM>, it is necessary to fill the thermally conductive material between the plurality of cylindrical batteries without gaps. This filling process requires a time. Therefore, manufacturing cost increases. Furthermore, in a case where the thermally conductive material is not sufficiently filled between the plurality of cylindrical batteries, cooling efficiency is concerned to lower. Furthermore, according to a technique disclosed in Non-Patent Literature <NUM>, in a case where the length of the thermally conductive member is shorter than an internal dimension of the case due to a manufacturing error, the both end parts of the thermally conductive member cannot be connected with the case. Therefore, heat of the batteries is hardly dissipated at the end parts which are not connected with the case. Therefore, it is concerned that cooling efficiency varies between the different batteries, and it is not possible to obtain desired cooling efficiency.

The present disclosure has been made to handle with at least part of the above-described issue, and an object of the present disclosure is to provide a technique which improves cooling efficiency of batteries of a battery pack while reducing manufacturing cost of the battery pack.

The present disclosure has been made to solve at least part of the above-described issue, and can be realized as following aspects.

According to this aspect, it is possible to reduce a dimension of a range occupied by the thermally conductive plate and the batteries in contact with the both sides of the thermally conductive plate in the direction orthogonal to a direction in which the plurality of other recessed parts are aligned while arranging the batteries on the both sides of the thermally conductive plate. Consequently, it is possible to more highly densely arrange the batteries in the case.

Note that the present disclosure can be realized as various aspects, and can be realized as forms such as a system including the battery pack, a battery pack manufacturing method, a computer program which causes manufacturing of the battery pack to be executed, a server apparatus which distributes this computer program, and a non-transitory storage medium which stores this computer program.

<FIG> is a schematic view illustrating a schematic configuration of a battery pack <NUM> according to a first embodiment. The battery pack <NUM> according to the first embodiment is used as, for example, an in-vehicle battery of an electric vehicle for which high output is requested. The battery pack <NUM> includes a plurality of batteries <NUM>, a plurality of thermally conductive members <NUM> and a case <NUM>. Note that an x axis direction, a y axis direction and a z axis direction are defined as follows for convenience of description. A direction in which the thermally conductive members <NUM> extend is the x axis direction. The x axis direction is also a direction in which the batteries <NUM> in contact with one surface of the thermally conductive member <NUM> are aligned. A direction vertical to an x axis on a horizontal plane which passes all the batteries <NUM> housed in the case <NUM> is the y axis direction. Furthermore, the direction vertical to the x axis direction and the y axis direction is the z axis direction.

The battery <NUM> is a lithium ion battery having a cylindrical shape. The battery pack <NUM> includes the plurality of batteries <NUM>. According to the present embodiment, respective center axes of the plurality of batteries <NUM> are arranged in substantially parallel to a z axis. The batteries <NUM> are electrically connected with an unillustrated input/output unit of the battery pack <NUM>. The batteries <NUM> receive and store, for example, electrical energy supplied from an external power supply of an electric vehicle and electrical energy generated by deceleration of the running electrical vehicle via this input/output unit. Furthermore, the batteries <NUM> output the electrical energy for driving a motor included in the electrical vehicle via the input/output unit.

As illustrated in <FIG>, the battery pack <NUM> includes rows B1 in which the six batteries <NUM> are aligned along the x axis direction, and rows B2 in which the five batteries <NUM> are aligned along the x axis direction. The rows B1 of the batteries <NUM> are referred to as the "battery rows B1" in this description. The rows B2 of the batteries <NUM> are referred to as the "battery rows B2" in this description. The battery pack <NUM> includes the eight battery rows B1 and the eight battery rows B2. The battery rows B1 and the battery rows B2 are alternately arranged in the y axis direction (see <FIG>).

The thermally conductive member <NUM> is a member of a plate shape formed by a material having high thermal conductivity such as metal. Note that a shape whose dimension in a thickness direction is <NUM>/<NUM> or less than a smaller dimension of a dimension in a vertical direction and a dimension in a horizontal direction is referred to as a "plate shape" in this description. The plate shape includes a corrugated plate.

As illustrated in <FIG>, the battery pack <NUM> includes the eight thermally conductive members <NUM>. Two surfaces of the largest plates are referred to as "principal surfaces" in this description. The thermally conductive member <NUM> includes two principal surfaces <NUM> and <NUM> to each of which the plurality of batteries <NUM> are fixed. A plurality of recessed and protrusion parts are formed on the principal surfaces <NUM> and <NUM> of the thermally conductive member <NUM>.

<FIG> is a partial enlarged view of the battery pack <NUM>. <FIG> is an enlarged view illustrating an enlarged A part in <FIG>. The thermally conductive member <NUM> includes recessed parts 21b, 21d, 21f and <NUM>. The thermally conductive member <NUM> is in contact with the one battery <NUM> of the plurality of batteries <NUM> in each of the recessed parts 21b, 21d, 21f and <NUM>. The thermally conductive member <NUM> further includes a plurality of other recessed parts 22a, 22c, 22e, <NUM> and 22i on the surface <NUM> opposite to the surface <NUM> provided with the recessed parts 21b, 21d, 21f and <NUM> of the thermally conductive member <NUM>. The thermally conductive member <NUM> is in contact with the one battery <NUM> of the plurality of batteries <NUM> in each of the plurality of other recessed parts 22a, 22c, 22e, <NUM> and 22i.

More specifically, as illustrated in <FIG>, the five protrusion parts and the four recessed parts are formed along the x axis direction and between one end part 20a on a minus x axis side and an other end part 20b on a plus x axis side on the principal surface <NUM> on a minus y axis side of the thermally conductive member <NUM>. These protrusion parts and recessed parts are aligned and arranged in order of a protrusion part 21a, the recessed part 21b, a protrusion part 21c, the recessed part 21d, a protrusion part 21e, the recessed part 21f, a protrusion part <NUM>, the recessed part <NUM> and a protrusion part 21i from the one end part 20a side.

The batteries <NUM> of the battery row B1 are fixed to the principal surface <NUM>. The four batteries <NUM> of the six batteries <NUM> of the battery row B1 are respectively fixed to the recessed part 21b, the recessed part 21d, the recessed part 21f and the recessed part <NUM>. The principal surface <NUM> on the minus y axis side of the thermally conductive member <NUM> is also referred to as "one principal surface". The curvatures of recessed surfaces of the recessed parts 21b, 21d, 21f and <NUM> substantially match with curvatures of outer circumferential surfaces of the batteries <NUM> of the columnar shapes.

According to this configuration, it is possible to place a larger area of the thermally conductive member <NUM> in contact with the batteries in the recessed parts 21b, 21d, 21f and <NUM> compared to an aspect where the thermally conductive member <NUM> is in planar contact with the batteries <NUM>. Consequently, the thermally conductive member <NUM> can efficiently take heat from the batteries compared to an aspect where the thermally conductive member <NUM> is in planar contact with the batteries.

Furthermore, according to this configuration, it is possible to reduce a dimension of a range W1 occupied by the thermally conductive member <NUM> and the batteries <NUM> in a recess direction of the recessed parts 21b, 21d, 21f and <NUM>, i.e., in the y axis direction compared to an aspect where the thermally conductive member <NUM> does not include the recessed parts 21b, 21d, 21f and <NUM> (see a lower stage in <FIG>). Consequently, it is possible to more densely arrange the batteries <NUM> in the case <NUM>.

As illustrated in <FIG>, the five recessed parts and the four protrusion parts are formed along the x axis direction and between the one end part 20a on the minus x axis side and the other end part 20b on the plus x axis side on the principal surface <NUM> on a plus y axis side of the thermally conductive member <NUM>. These recessed parts and protrusion parts are aligned and arranged in order of the recessed part 22a, a protrusion part 22b, the recessed part 22c, a protrusion part 22d, the recessed part 22e, a protrusion part 22f, the recessed part <NUM>, a protrusion part <NUM> and the recessed part 22i from the one end part 20a side. Each of the recessed part 22a, the recessed part 22c, the recessed part 22e, the recessed part <NUM> and the recessed part 22i of the principal surface <NUM> is formed at a position at which each of the protrusion part 21a, the protrusion part 21c, the protrusion part 21e, the protrusion part <NUM> and the protrusion part 21i of the principal surface <NUM> is formed. Each of the protrusion part 22b, the protrusion part 22d, the protrusion part 22f and the protrusion part <NUM> of the principal surface <NUM> is formed at a position at which each of the recessed part 21b, the recessed part 21d, the recessed part 21f and the recessed part <NUM> of the principal surface <NUM> is formed. As a result, the recessed parts 21b, 21d, 21f and <NUM> are positioned between the two neighboring recessed parts of the other recessed parts 22a, 22c, 22e, <NUM> and 22i in the x axis direction in which the other recessed parts 22a, 22c, 22e, <NUM> and 22i are aligned.

The batteries <NUM> of the battery row B2 are fixed to the principal surface <NUM>. The five batteries <NUM> of the battery row B2 are respectively fixed to the recessed part 22a, the recessed part 22c, the recessed part 22e, the recessed part <NUM> and the recessed part 22i. The principal surface <NUM> on the plus y axis side of the thermally conductive member <NUM> is also referred to as an "other principal surface". The curvatures of recessed surfaces of the recessed parts 22a, 22c, 22e, <NUM> and 22i substantially match with curvatures of outer circumferential surfaces of the batteries <NUM> of the columnar shapes.

According to this aspect, it is possible to reduce a dimension of a range W2 occupied by the thermally conductive member <NUM> and the batteries <NUM> in contact with the both sides of the thermally conductive member <NUM> in the y axis direction vertical to the x axis direction in which the plurality of recessed parts 22a, 22c, 22e, <NUM> and 22i are aligned while arranging the batteries <NUM> on the both sides of the thermally conductive member <NUM> (see the lower stage in <FIG>). Consequently, it is possible to more densely arrange the batteries <NUM> in the case <NUM>.

<FIG> is a perspective view of a battery module <NUM> included in the battery pack <NUM>. <FIG> is an explanatory view illustrating processing of exchanging the battery modules <NUM> in the battery pack <NUM>. According to the present embodiment, the one thermally conductive member <NUM> and the <NUM> batteries <NUM> fixed to this one thermally conductive member <NUM>, i.e., the one battery row B1 and the one battery row B2 constitute the one battery module <NUM> illustrated in <FIG>. As illustrated in <FIG>, the battery pack <NUM> includes the eight battery modules <NUM>.

According to the present embodiment, as illustrated in <FIG>, when a failure occurs in one battery 10d, a battery module 15o including the battery 10d which has caused this failure is detached (an outlined arrow T1 in <FIG>). Subsequently, a new battery module 15n is attached to a place at which the battery module 15o has been detached (an outlined arrow T2 in <FIG>).

The case <NUM> houses the plurality of batteries <NUM> and the plurality of thermally conductive members <NUM> inside (see <FIG>). The case <NUM> is formed by, for example, metal having high thermal conductivity. The case <NUM> includes a plurality of wall parts <NUM>, <NUM>, <NUM> and <NUM> which form a housing space 30a for housing the plurality of batteries <NUM> and the plurality of thermally conductive members <NUM>, a plurality of grip parts <NUM>, and a plurality of grip parts <NUM>. Note that <FIG> illustrates the battery pack <NUM> in a state where the wall part <NUM> has been detached from the case <NUM> for ease of understanding of the technique. The case <NUM> is connected with an unillustrated external heat dissipation device. The case <NUM> transfers heat generated by the batteries <NUM> to this heat dissipation device.

As illustrated in <FIG>, the wall part <NUM> and the wall part <NUM> are arranged at positions facing each other (see an upper stage center part and a lower stage center part in <FIG>). The wall part <NUM> and the wall part <NUM> form the housing space 30a in which the plurality of batteries <NUM> and the plurality of thermally conductive members <NUM> are arranged. A surface on the housing space 30a side of the wall part <NUM> is provided with the plurality of grip parts <NUM> (see an upper stage in <FIG> and an upper stage in <FIG>). A surface on the housing space 30a side of the wall part <NUM> is provided with the plurality of grip parts <NUM> (see a lower stage in <FIG> and a lower stage in <FIG>). Details of configurations of the grip parts <NUM> and <NUM> will be described later. The wall part <NUM> and the wall part <NUM> are also referred to as "a pair of side surface parts".

<FIG> is a perspective view of the battery pack <NUM> according to the present embodiment from which part of the components of the battery pack <NUM> have been removed. The wall part <NUM> is connected with an end part on a minus z axis direction side of the wall part <NUM>, and an end part on the minus z axis direction side of the wall part <NUM> (see a lower stage center part in <FIG>). The wall part <NUM> corresponds to a bottom part of the case <NUM>. As illustrated in <FIG>, the plurality of batteries <NUM> housed in the housing space 30a is placed on the wall part <NUM>. The wall part <NUM> is connected with an end part on a plus z axis direction side of the wall part <NUM>, and an end part on the plus z axis direction side of the wall part <NUM>. The wall part <NUM> is arranged at a position which faces the wall part <NUM>. As illustrated in <FIG>, a plurality of fins 34a are formed in an outer wall surface of the wall part <NUM>. Consequently, the case <NUM> can dissipate heat to the above-described heat dissipation device and, in addition, efficiently dissipate heat generated by the batteries <NUM> to an outside by using the fins 34a.

As illustrated in the upper stage in <FIG>, the grip part <NUM> is arranged on a surface on the housing space 30a side of the wall part <NUM>. The grip part <NUM> includes two slit formation parts 36a and 36b. The two slit formation parts 36a and 36b each protrude from the surface on the housing space 30a side of the wall part <NUM> to a plus x axis direction. As illustrated in <FIG>, the two slit formation parts 36a and 36b are arranged so as to form a gap of a certain interval. On each of the two slit formation parts 36a and 36b, inner wall surfaces 36c and 36d of planar shapes which face each other in the y axis direction are formed. A space between the inner wall surface 36c and the inner wall surface 36d is a slit S which penetrates the grip part <NUM> in the z axis direction.

The grip part <NUM> is not in contact with an end surface <NUM> of the thermally conductive member <NUM> in a minus x axis direction. The wall part <NUM> which supports the grip part <NUM> is not in contact with the end surface <NUM> of the thermally conductive member <NUM>, either. The grip part <NUM> regulates displacement of each of the surfaces <NUM> and <NUM> of the thermally conductive member <NUM> in the y axis direction vertical to each of the surfaces <NUM> and <NUM> which are connected with the end surface <NUM> and positioned on sides opposite to each other. That is, the surfaces <NUM> and <NUM> of the thermally conductive member <NUM> are positioned within a range defined by the grip part <NUM> in the y axis direction. The grip part <NUM> is in contact with at least one of the two surfaces <NUM> and <NUM>, and thereby holds the end part 20a of the thermally conductive member <NUM>. According to the present embodiment, the grip part <NUM> is substantially in contact with the two surfaces <NUM> and <NUM>, and thereby determines the position of the end part 20a of the thermally conductive member <NUM>.

According to this configuration, it is possible to transfer heat generated by the batteries <NUM> to the case <NUM> through the thermally conductive member <NUM> which is in contact with the batteries <NUM>, and the grip part <NUM> which is in contact with at least one of the two surfaces <NUM> and <NUM> of the thermally conductive member <NUM>. Furthermore, even in a case where the position of the end surface <NUM> of the thermally conductive member <NUM> with respect to the grip part <NUM> is displaced from a designed position due to a manufacturing error of one or both of the thermally conductive member <NUM> and the case <NUM>, it is possible to transfer the heat generated by the batteries to the case <NUM>.

More specifically, as illustrated in <FIG>, the inner wall surface 36c and the inner wall surface 36d of the grip part <NUM> sandwich the one end part 20a of the thermally conductive member <NUM>, and thereby grip the one end part 20a of the thermally conductive member <NUM>. As illustrated in <FIG>, the one end part 20a of the thermally conductive member <NUM> is gripped by the grip part <NUM> in the slit S.

In this state, at least one of the two facing surfaces 36c and 36d of the grip part <NUM> which define the slit S is in contact with at least one of the two surfaces <NUM> and <NUM> of the thermally conductive member <NUM> positioned on the sides opposite to each other. The wall part <NUM> is not in contact with the end surface <NUM> of the thermally conductive member <NUM> via a surface 36e which connects the two facing surfaces 36c and 36d in the slit S.

A gap between the one end part 20a of the thermally conductive member <NUM> and the grip part <NUM> is filled by a thermally conductive grease <NUM>. As a result, the surface 36e which connects the two facing surfaces 36c and 36d in the slit S and the end surface <NUM> of the thermally conductive member <NUM> are connected by the thermally conductive grease <NUM> (see an upper stage center part in <FIG>).

Accordingly, it is possible to transfer heat from the end surface <NUM> of the thermally conductive member <NUM> to the surface 36e which connects the two facing surfaces 36c and 36d in the slit S through the thermally conductive grease <NUM>. Consequently, even in a case where the position of the end surface <NUM> of the thermally conductive member <NUM> with respect to the grip part <NUM> is displaced due to a manufacturing error of one or both of the thermally conductive member <NUM> and the case <NUM> or an assembly error of the thermally conductive member <NUM> and the case <NUM>, it is possible to transfer heat from the end surface <NUM> of the thermally conductive member <NUM> to the grip part <NUM>.

According to a preferred embodiment, sizes of the two slit formation parts 36a and 36b in the x axis direction are different to prevent an interference with the batteries <NUM> fixed to the thermally conductive member <NUM>. More specifically, the dimension of the slit formation part 36b in the x axis direction is smaller than the dimension of the slit formation part 36a in the x axis direction. As a result, an interference between the battery <NUM> at an end of the battery row B1 and the slit formation part 36b is prevented.

Note that <FIG> illustrates the enlarged width of the slit S compared to the width of the one end part 20a of the thermally conductive member <NUM> to clarify a positional relationship between the principal surface <NUM> of the thermally conductive member <NUM>, the inner wall surface 36d of the slit formation part 36b and the thermally conductive grease <NUM> in the slit S. However, the inner wall surfaces 36c and 36d are actually substantially in contact with the principal surfaces <NUM> and <NUM> of the thermally conductive member <NUM>, respectively. The thermally conductive grease <NUM> fills minute gaps of various portions between the inner wall surface 36d and the principal surface <NUM>. As a result, the thermally conductive grease <NUM> functions to increase an area of a part at which heat is transferred between the inner wall surface 36d and the principal surface <NUM>.

The thermally conductive member <NUM> and the grip part <NUM> are configured such that the thermally conductive member <NUM> can be detached from the grip part <NUM> by sliding in the slit S the thermally conductive member <NUM> with respect to the grip part <NUM>.

According to this configuration, when the thermally conductive member <NUM> and the plurality of batteries <NUM> in contact with the thermally conductive member <NUM> cause abnormalities, the abnormalities can be dealt with as follows. That is, it is possible to easily detach the thermally conductive member <NUM> and the plurality of batteries <NUM> in contact with the thermally conductive member <NUM> from the case <NUM> to exchange with the new thermally conductive member <NUM> and the plurality of new batteries <NUM> in contact with the new thermally conductive member <NUM> (see <FIG>).

The grip part <NUM> is arranged on a surface on the housing space 30a side of the wall part <NUM> (see a lower stage in <FIG>). The grip part <NUM> is provided in a shape symmetrical to that of the grip part <NUM> around an axis parallel to the y axis direction. As a result, the grip part <NUM> exhibits the same function as that of the grip part <NUM>.

Accordingly, it is possible to efficiently transfer heat of the batteries <NUM> to the case <NUM> through the both end parts 20a and 20b of the thermally conductive member <NUM>. Furthermore, even in a case where the positions of the end surfaces <NUM> and <NUM> at the both ends of the thermally conductive member <NUM> in the x axis direction with respect to the grip part <NUM> are displaced due to a manufacturing error of one or both of the thermally conductive member <NUM> and the case <NUM> or an assembly error of the thermally conductive member <NUM> and the case <NUM>, it is possible to transfer heat generated by the batteries <NUM> to the case <NUM>.

More specifically, the grip part <NUM> includes two slit formation parts 37a and 37b. The two slit formation parts 37a and 37b each protrude from the surface on the housing space 30a side of the wall part <NUM> to the minus x axis direction. The two slit formation parts 37a and 37b are arranged so as to form a gap of a certain interval substantially equal to the gap of the grip part <NUM>. On each of the two slit formation parts 37a and 37b, inner wall surfaces of planar shapes which face each other in the y axis direction are formed. A space between these inner wall surfaces is a slit which penetrates the grip part <NUM> in the z axis direction.

The grip part <NUM> is not in contact with the end surface <NUM> of the thermally conductive member <NUM> in the plus x axis direction. The wall part <NUM> which supports the grip part <NUM> is not in contact with the end surface <NUM> of the thermally conductive member <NUM>, either. The grip part <NUM> regulates displacement of each of the surfaces <NUM> and <NUM> of the thermally conductive member <NUM> in the y axis direction vertical to each of the surfaces <NUM> and <NUM> which are connected with the end surface <NUM> and positioned on the sides opposite to each other, is in contact with at least one of the two surfaces, and thereby holds the end part 20b of the thermally conductive member <NUM>.

More specifically, as illustrated in <FIG>, the two inner wall surfaces respectively formed on the two slit formation parts 37a and 37b of the grip part <NUM> sandwich the other end part 20b of the thermally conductive member <NUM>, and thereby grip the other end part 20b of the thermally conductive member <NUM>. According to the present embodiment, a gap between the other end part 20b of the thermally conductive member <NUM> gripped by the grip part <NUM>, and the grip part <NUM> in the slit formed in the grip part <NUM> is filled by the same thermally conductive grease as that of the grip part <NUM> (see <FIG>). Similar to the grip part <NUM>, sizes of the two slit formation parts 37a and 37b in the x axis direction are different to prevent an interference with the batteries <NUM> fixed to thermally conductive member <NUM>. More specifically, the dimension of the slit formation part 37b in the x axis direction is smaller than the dimension of the slit formation part 37a in the x axis direction. As a result, an interference between the battery <NUM> at an end of the battery row B1 and the slit formation part 37b is prevented.

The both end parts 20a and 20b are inserted in the respective slits of the two grip parts <NUM> and <NUM> such that each of the eight battery modules <NUM> included in the battery pack <NUM> is gripped by the grip parts <NUM> and <NUM> (see <FIG>). By detaching the wall part <NUM> from the case <NUM> and then sliding the arbitrary battery module <NUM> in the plus z axis direction with respect to the grip parts <NUM> and <NUM>, the arbitrary battery module <NUM> can be detached from the case <NUM> (see the arrow T1 in <FIG>). Then, by sliding the new battery module <NUM> in the minus z axis direction with respect to the grip part <NUM> and <NUM>, this new battery module <NUM> is attached to the case <NUM> (see the arrow T2 in <FIG>). Consequently, it is possible to easily exchange the battery module <NUM> as described above.

Next, an effect of the battery pack <NUM> according to the present embodiment will be described. First, an issue of a battery pack <NUM> according to a comparative example will be described with reference to <FIG> and <FIG>.

<FIG> and <FIG> are explanatory views for explaining the issue of the battery pack <NUM> according to the comparative example. In the battery pack <NUM> according to the comparative example illustrated in <FIG>, the plurality of batteries <NUM> are aligned in a row and arranged between a pair of wall parts <NUM> and <NUM> of a case of the battery pack <NUM>. Thermally conductive members <NUM> in contact with the plurality of these batteries <NUM> are arranged on both sides of the plurality of batteries <NUM>, and are formed to surround the batteries <NUM>. The thermally conductive member <NUM> is arranged between the pair of wall parts <NUM> and <NUM>. In the battery pack <NUM> according to the comparative example, both end parts of the thermally conductive member <NUM> are respectively fixed by, for example, welding to the wall parts <NUM> and <NUM>.

An actual size of the thermally conductive member <NUM> is determined at a manufacturing stage. The length of the thermally conductive member <NUM> in a direction in which the plurality of batteries <NUM> are aligned may differ per individual thermally conductive member <NUM> due to a manufacturing error in some cases. Hence, the plurality of thermally conductive members <NUM> include the relatively short thermally conductive members <NUM> illustrated in <FIG>, and the relatively long thermally conductive members <NUM> illustrated in <FIG>. In a case where, for example, a length L01 of the thermally conductive member <NUM> in a direction in which the batteries <NUM> in contact with the thermally conductive member <NUM> are aligned is shorter than a distance L0 between the pair of wall parts <NUM> and <NUM> as illustrated in <FIG>, while one end part <NUM> of the thermally conductive member <NUM> can be connected with the wall part <NUM>, an other end part <NUM> cannot be connected with the wall part <NUM>. Consequently, heat of the batteries <NUM> on the end part <NUM> side of the thermally conductive member <NUM> is hardly dissipated to an outside through the case in the manufactured battery pack <NUM>.

Furthermore, in a case where a length L02 of the thermally conductive member <NUM> in the direction in which the batteries <NUM> in contact with the thermally conductive member <NUM> are aligned is longer than the distance L0 between the pair of wall parts <NUM> and <NUM> as illustrated in <FIG>, the thermally conductive member <NUM> to which the batteries <NUM> are fixed cannot be arrange between the pair of wall parts <NUM> and <NUM> (see the thermally conductive member <NUM> indicated by a broken line in <FIG>). Consequently, it is necessary to manufacture the thermally conductive member <NUM> such that the length of the thermally conductive member <NUM> in the direction in which the batteries <NUM> are aligned is not longer than the distance L0 between the pair of wall parts <NUM> and <NUM>. On the other hand, as described with reference to <FIG>, in the case where the length of the thermally conductive member <NUM> is shorter than the distance L0 between the pair of wall parts <NUM> and <NUM>, one of the two end parts <NUM> and <NUM> cannot be connected with the wall parts <NUM> and <NUM>.

Therefore, cooling efficiency differs between the plurality of thermally conductive members <NUM> depending on the lengths of the thermally conductive members <NUM>. As a result, the cooling efficiency varies per thermally conductive member <NUM>, and the cooling efficiency of the overall battery pack <NUM> lowers. To prevent the variation of the cooling efficiency, the lengths of the thermally conductive members <NUM> need to be accurately managed to match with or become slightly shorter than the distance L0 between the pair of wall parts <NUM> and <NUM> which is an upper limit. That is, it is necessary to set a small manufacturing tolerance for the thermally conductive members <NUM>. Therefore, manufacturing cost of the battery pack <NUM> increases.

<FIG> and <FIG> are explanatory views for explaining the effect of the battery pack <NUM> according to the present embodiment. As described above, according to the battery pack <NUM> according to the present embodiment, the pair of wall parts <NUM> and <NUM> are provided with the grip parts <NUM> and <NUM>, respectively, which grip the two end parts 20a and 20b of the thermally conductive member <NUM>, respectively (see <FIG> and <FIG>). In, for example, a manufacturing process of the thermally conductive member <NUM>, a reference dimension of the length of the thermally conductive member <NUM> can be set to the distance L1 between a center line C36 of the grip part <NUM> and a center line C37 of the grip part <NUM> (see an upper stage in <FIG>). Note that the center line C36 is a line which indicates a center position of the slit S of the grip part <NUM> in the x axis direction. The center line C37 is a line which indicates a center position of the slit of the grip part <NUM> in the x axis direction. According to this aspect, even in a case where a length L11 of the thermally conductive member <NUM> in a direction in which the batteries <NUM> in contact with the thermally conductive member <NUM> are aligned is shorter than the length L1 as illustrated in <FIG>, the thermally conductive member <NUM> can be held by the grip parts <NUM> and <NUM>. Furthermore, even in a case where a length L12 of the thermally conductive member <NUM> in the direction in which the batteries <NUM> in contact with the thermally conductive member <NUM> are aligned is longer than the length L1 as illustrated in <FIG>, the thermally conductive member <NUM> can be arranged in the case <NUM>. Consequently, the manufacturing tolerance of the thermally conductive member <NUM> can be made greater than the manufacturing tolerance of the thermally conductive member <NUM> according to the comparative example. Consequently, the manufacturing cost of the battery pack <NUM> is reduced. Furthermore, in the both cases, the two end parts 20a and 20b of the thermally conductive member <NUM> are gripped by the two grip parts <NUM> and <NUM>, respectively, so that heat generated by the batteries <NUM> transfers to the case <NUM> through the thermally conductive member <NUM> (see <FIG> and <FIG>). Consequently, the cooling efficiency varies becomes less between the plurality of thermally conductive members <NUM>, so that it is possible to improve the cooling efficiency.

According to the above-described battery pack <NUM> according to the present embodiment, the thermally conductive members <NUM> to which the plurality of batteries <NUM> are fixed are gripped by the grip parts <NUM> and <NUM> provided to the case <NUM>. Consequently, the heat generated by the batteries <NUM> transfers to the case <NUM> through the thermally conductive members <NUM>, and thereby is dissipated from the case <NUM> to the outside of the battery pack <NUM>. The grip parts <NUM> and <NUM> grip the thermally conductive members <NUM> by sandwiching the two end parts 20a and 20b of the thermally conductive members <NUM>. Consequently, even in a case where the positions of the two end parts 20a and 20b of the thermally conductive members <NUM> with respect to the grip parts <NUM> and <NUM> are displaced due to variations of the lengths of the thermally conductive member <NUM>, the grip parts <NUM> and <NUM> can grip the thermally conductive members <NUM>. Consequently, even in a case where the manufacturing tolerance of the length is made great compared to the comparative example where the manufacturing tolerance of the length of the thermally conductive members needs to be strictly managed to connect the both end parts with the case, it is possible to transfer the heat generated by the batteries <NUM> to the case <NUM>. Consequently, it is possible to improve the cooling efficiency of the batteries <NUM> while reducing the manufacturing cost of the battery pack <NUM>.

Furthermore, according to the battery pack <NUM> according to the present embodiment, the two end parts 20a and 20b of the thermally conductive member <NUM> are gripped by the grip parts <NUM> and <NUM>, respectively, which are provided to the pair of wall parts <NUM> and <NUM>. Consequently, compared to the thermally conductive member whose one end part is fixed and whose other end part is fixed to the case, it is possible to make the manufacturing tolerance of the thermally conductive member <NUM> greater. Consequently, it is possible to further reduce the manufacturing cost of the battery pack <NUM>.

Furthermore, in the battery pack <NUM> according to the present embodiment, the batteries <NUM> have the columnar shapes. The nine batteries <NUM> are in contact with the recessed parts 21b, 21d, 21f, <NUM>, 22a, 22c, 22e, <NUM> and 22i of the thermally conductive member <NUM> having the plate shape. More specifically, part of each of the nine batteries <NUM> is positioned in the recessed parts 21b, 21d, 21f, <NUM>, 22a, 22c, 22e, <NUM> and 22i of the thermally conductive member <NUM>. Consequently, a volume of a minimum cuboid surrounding a space occupied by the one thermally conductive member <NUM> and the plurality of batteries <NUM> in contact with this thermally conductive member <NUM> is smaller than a volume of a minimum cuboid surrounding a space occupied by one thermally conductive member and a plurality of batteries in contact with this one thermally conductive member in a case where the batteries of cylindrical shapes are in contact with principal surfaces of the thermally conductive member of flat plate shapes. Consequently, it is possible to house the more batteries <NUM> inside the case <NUM>. Consequently, it is possible to improve a packing density of the batteries <NUM> while improving the cooling efficiency of the batteries <NUM>.

Furthermore, according to the battery pack <NUM> according to the present embodiment, each of the recessed part 22a, the recessed part 22c, the recessed part 22e, the recessed part <NUM> and the recessed part 22i of the principal surface <NUM> of the thermally conductive member <NUM> is formed at a position at which each of the protrusion part 21a, the protrusion part 21c, the protrusion part 21e, the protrusion part <NUM> and the protrusion part 21i of the principal surface <NUM> is formed. The batteries <NUM> arranged on the principal surface <NUM> side of the thermally conductive member <NUM> are fixed to the recessed parts 21b, 21d, 21f and <NUM> of the principal surface <NUM>. Furthermore, the batteries <NUM> arranged on the principal surface <NUM> side of the thermally conductive member <NUM> are fixed to the recessed parts 22a, 22c, 22e, <NUM> and 22i of the principal surface <NUM>. More specifically, the nine batteries <NUM> are arranged in a zig-zag pattern along a longitudinal direction of the thermally conductive member <NUM> while being in contact with the recessed parts 21b, 21d, 21f, <NUM>, 22a, 22c, 22e, <NUM> and 22i of the thermally conductive member <NUM>. Consequently, according to the battery pack <NUM>, the volume of the minimum cuboid surrounding the space occupied by the one thermally conductive member and the plurality of batteries in contact with this one thermally conductive member is much smaller than the volume of the minimum cuboid surrounding the space occupied by the one thermally conductive member and the plurality of batteries in contact with this one thermally conductive member in a case where the batteries are in contact with each of the two principal surfaces included in the thermally conductive member of the flat plate shape. Consequently, it is possible to house the much more batteries <NUM> inside the case <NUM>. Consequently, it is possible to improve the packing density of the batteries <NUM> while improving the cooling efficiency of the batteries <NUM>.

Furthermore, according to the battery pack <NUM> according to the present embodiment, the battery pack <NUM> includes the plurality of battery modules <NUM>. The one battery module <NUM> is constituted by the one thermally conductive member <NUM>, and the plurality of batteries <NUM> fixed to the one thermally conductive member <NUM>. The grip parts <NUM> and <NUM> include the slits in which one of the two end parts 20a and 20b of the thermally conductive member <NUM> included in the battery module <NUM> can be inserted, and are configured to enable attachment and detachment of the battery module <NUM> by sliding the battery module <NUM> with respect to the slit. Consequently, it is possible to return the battery pack <NUM> to a normal state by exchanging only the battery module <NUM> which has caused an abnormality instead of the whole battery pack <NUM> when the one battery module <NUM> causes the abnormality. Furthermore, by sliding the battery module <NUM> with respect to the slit, the battery module <NUM> can be attached and detached, so that it is possible to easily exchange the battery module <NUM>.

Furthermore, according to the battery pack <NUM> according to the present embodiment, the gaps between the two end parts 20a and 20b of the thermally conductive member <NUM> gripped by the grip parts <NUM> and <NUM>, and the grip parts <NUM> and <NUM> are filled by the thermally conductive grease <NUM>. Consequently, even when relatively short length of the thermally conductive member <NUM> creates the gaps between the end parts 20a and 20b of the thermally conductive member <NUM> and the grip parts <NUM> and <NUM> , the thermally conductive grease <NUM> which fills the gaps can transfer heat from the thermally conductive member <NUM> to the case <NUM> through the grip parts <NUM> and <NUM>. Consequently, it is possible to further improve the cooling efficiency of the batteries <NUM>.

The grip part <NUM> , the part of the wall part <NUM> which supports the grip part <NUM>, and the part of the wall part <NUM> which forms the inner wall surface 36e of the slit S in the present embodiment are also referred to as a "holding part". The grip part <NUM>, the part of the wall part <NUM> which supports the grip part <NUM>, and the part of the wall part <NUM> which forms the inner wall surface of the slit of the grip part <NUM> are also referred to as an "other holding part". The thermally conductive grease <NUM> is also referred to as a "grease".

<FIG> is a schematic view illustrating a schematic configuration of a battery pack <NUM> according to a second embodiment. The battery pack <NUM> according to the second embodiment differs from the battery pack <NUM> according to the first embodiment illustrated in <FIG> in including heat shielding members. Other points of the battery pack <NUM> according to the second embodiment are the same as those of the battery pack <NUM> according to the first embodiment.

The battery pack <NUM> according to the present embodiment includes the plurality of batteries <NUM>, the thermally conductive members <NUM>, heat shielding members <NUM> and a case <NUM>.

The heat shielding member <NUM> is a member of a plate shape arranged between the neighboring battery modules <NUM> among the plurality of battery modules <NUM> arranged in the case <NUM>. The heat shielding member <NUM> has low thermal conductivity, and is formed by a material having fire retardancy. More specifically, the heat shielding member <NUM> is made of a material having lower thermal conductivity than that of the material of the thermally conductive member <NUM>. The thermal conductivity of the material of the heat shielding member <NUM> is lower than thermal conductivity of the material of the case <NUM> and thermal conductivity of the thermally conductive grease <NUM>. According to the present embodiment, the battery pack <NUM> includes the six heat shielding members <NUM>.

That is, the heat shielding member <NUM> is arranged between a combination of the thermally conductive member <NUM> and the plurality of batteries <NUM> which constitute the certain battery module <NUM>, and a combination of the another thermally conductive member <NUM> and the plurality of other batteries <NUM> which constitute the another battery module <NUM>.

According to this configuration, it is possible to prevent heat from being transferred between the plurality of batteries <NUM> which transfer heat to each other through the thermally conductive member <NUM>, and the plurality of other batteries <NUM> which transfer heat to each other through the another thermally conductive member <NUM>. As a result, when the one or more batteries of the plurality of batteries <NUM> cause abnormal heating, it is possible to reduce a probability that this heat causes a negative influence on the plurality of other batteries <NUM>. Furthermore, when the one or more batteries of the plurality of other batteries <NUM> cause abnormal heating, it is possible to reduce a probability that this heat causes a negative influence on the plurality of batteries <NUM>.

The case <NUM> includes the plurality of wall parts <NUM>, <NUM>, <NUM> and <NUM> which form a housing space 40a which houses the plurality of batteries <NUM>, the plurality of thermally conductive members <NUM> and the plurality of heat shielding members <NUM>, the plurality of grip parts <NUM> and the plurality of grip parts <NUM> which respectively grip the thermally conductive members <NUM>, and the plurality of grip parts <NUM> and the plurality of grip parts <NUM> which respectively grip the heat shielding members <NUM>.

The grip part <NUM> is arranged between the neighboring grip parts <NUM> on the surface on the housing space 40a side of the wall part <NUM> (see an upper stage in <FIG>). The grip part <NUM> protrudes from the surface on the housing space 30a of the wall part <NUM> side to the plus x axis direction. The grip part <NUM> includes a slit in which an end part of the heat shielding member <NUM> can be inserted. The grip part <NUM> grips the end part of the heat shielding member <NUM> when the end part of the heat shielding member <NUM> is inserted therein.

The grip part <NUM> is arranged between the neighboring grip parts <NUM> on the surface on the housing space 40a side of the wall part <NUM> (see a lower stage in <FIG>). The grip part <NUM> protrudes from the surface on the housing space 30a side of the wall part <NUM> to the minus x axis direction. The grip part <NUM> includes a slit in which an end part of the heat shielding member <NUM> can be inserted. The grip part <NUM> grips the end part of the heat shielding member <NUM> when the end part of the heat shielding member <NUM> is inserted therein.

The two end parts of the heat shielding member <NUM> are respectively held in the slits included in the two grip parts <NUM> and <NUM>, and thereby supported. As a result, the heat shielding member <NUM> shields between the neighboring battery module <NUM> and battery module <NUM>. The heat shielding member <NUM> is configured to be exchangeable by being slid with respect to the grip parts <NUM> and <NUM>.

According to the above-described battery pack <NUM> according to the present embodiment, the battery pack <NUM> includes the plurality of battery modules <NUM> which are each constituted by the one thermally conductive member <NUM> and the plurality of batteries <NUM> in contact with the one thermally conductive member <NUM>, and the heat shielding members <NUM> are arranged between the neighboring battery modules <NUM>. Consequently, it is possible to prevent heat exchange between the neighboring battery modules <NUM>, and prevent an abnormality of the one battery module <NUM> from influencing the neighboring battery module <NUM> of the one battery module <NUM> when the abnormality occurs in an external appearance of the battery <NUM> included in the one battery module <NUM>. Consequently, it is possible to prevent the abnormality of the one battery module <NUM> from influencing the overall battery pack <NUM>.

The present disclosure is not limited to the above embodiments, can be carried out as various aspects without departing from the scope of the appended claims, and can be also modified as follows, for example.

According to the above-described embodiments, the batteries <NUM> are fixed to the thermally conductive members <NUM>. However, the batteries do not necessarily need to be fixed to the thermally conductive members, and only need to be in contact with the thermally conductive members. The batteries and the thermally conductive members are in contact, so that it is possible to transfer heat generated by the batteries to the case through the thermally conductive members. Consequently, it is possible to improve the cooling efficiency.

According to the above-described embodiments, the grip parts <NUM> and <NUM> are provided to the pairs of the wall parts <NUM> and <NUM> of the case <NUM>, respectively. However, the grip parts may be provided to one of the wall parts. In a case where the one grip part can grip one end part of the thermally conductive member, it is possible to transfer heat of the batteries to the case while making the manufacturing tolerance of the thermally conductive member greater.

According to the above-described embodiments, the plurality of recessed and protrusion parts are formed on the principal surfaces <NUM> and <NUM> of the thermally conductive members <NUM>, and the batteries <NUM> are fixed to the recessed parts. However, the shape of the thermally conductive member <NUM> is not limited to this. The thermally conductive member <NUM> may have a flat plate shape. Furthermore, part of the batteries <NUM> of the plurality of batteries <NUM> may be in contact with and fixed to the recessed parts of the thermally conductive member, and part of the other batteries <NUM> may be in contact with and fixed to flat plate parts of the thermally conductive member.

According to the above-described embodiments, each of the recessed part 22a, the recessed part 22c, the recessed part 22e, the recessed part <NUM> and the recessed part 22i of the principal surface <NUM> is formed at a position at which each of the protrusion part 21a, the protrusion part 21c, the protrusion part 21e, the protrusion part <NUM> and the protrusion part 21i of the principal surface <NUM> is formed. In other words, the thermally conductive member <NUM> is a member of a plate shape whose thickness is substantially uniform, and is corrugated in the y axis direction. However, the shape of the thermally conductive member <NUM> is not limited to this. Furthermore, the batteries <NUM> are arranged on the both sides of the thermally conductive member <NUM>, yet may be arranged on one side.

According to the above-described embodiments, the battery pack <NUM> includes the plurality of battery modules <NUM>. By sliding the individual battery module <NUM> in the z axis direction with respect to the grip parts <NUM> and <NUM>, it is possible to attach and detach the battery module <NUM> to and from the case <NUM>. However, the battery modules <NUM> may be housed in the case in a mode that the battery modules <NUM> are fixed to the case by bolts or nuts, that is, the battery modules <NUM> cannot be detached from the case only by sliding the battery modules <NUM>.

According to the above-described embodiments, the gap between the one end part 20a of the thermally conductive member <NUM> gripped by the grip part <NUM>, and the grip part <NUM> is filled by grease <NUM>. However, a material which fills the gap between the end part of the thermally conductive member <NUM> and the grip part is not limited to this. A gap between an external surface of the end part of the thermally conductive member and the grip part may be filled by a thermally conductive grease <NUM>. Other alternatives that are not part of the present invention may include an adhesive material, such that the end part of the thermally conductive member and the grip part may be fixed. Furthermore, there may not be a material which fills the gap.

Claim 1:
A battery pack (<NUM>) comprising:
a plurality of batteries (<NUM>);
a thermally conductive plate (<NUM>) having two opposite principal surfaces (<NUM>, <NUM>) connected by side surfaces (<NUM>, <NUM>), said thermally conductive plate (<NUM>) being in contact with the plurality of batteries (<NUM>); and
a case (<NUM>) which houses the plurality of batteries (<NUM>) and the thermally conductive plate (<NUM>),
wherein the case (<NUM>) includes a grip part (<NUM>) which is not in contact with a side surface (<NUM>, <NUM>) of the thermally conductive plate (<NUM>), wherein the grip part (<NUM>) regulates displacement of said two principal surfaces (<NUM>, <NUM>) of the thermally conductive plate (<NUM>) in a direction orthogonal to said two principal surfaces (<NUM>, <NUM>), the grip part (<NUM>) being in contact with at least one of the two principal surfaces (<NUM>, <NUM>), and thereby holding an end part of the thermally conductive plate (<NUM>), and
wherein the grip part (<NUM>) includes a slit in which the end part of the thermally conductive plate (<NUM>) is inserted, wherein the grip part (<NUM>) is in contact with at least one of the two principal surfaces (<NUM>, <NUM>) of the thermally conductive plate (<NUM>) via at least one of two facing surfaces of the grip part (<NUM>), wherein the two facing surfaces define the slit, wherein the grip part (<NUM>) is not in contact with the side surface (<NUM>) via a surface of the grip part (<NUM>) which connects the two facing surfaces which define the slit, characterized in that
the thermally conductive plate (<NUM>) and the grip part (<NUM>) are configured such that the thermally conductive plate (<NUM>) is detachable from the grip part (<NUM>) by sliding in the slit the thermally conductive plate (<NUM>) with respect to the grip part (<NUM>), and
the battery pack (<NUM>) further comprises a grease (<NUM>) which connects the surface which connects the two facing surfaces which define the slit, and the side surface (<NUM>) of the thermally conductive plate (<NUM>).