Patent Description:
CO<NUM> emission regulations for vehicles are being required, which is promoting the electrification of vehicles. With the electrification of vehicles, batteries that store electric power for drive motors are being mounted in vehicles. This battery is also charged with electric power regenerated by the power generation motor when the vehicle decelerates (there are occasions when the drive motor generates power). In order to achieve a sufficient driving range, it is necessary to mount a battery having a large capacity, which increases the volume of the battery as well as the weight of the battery. Large, heavy batteries tend to be mounted in the floor of the vehicle cabin, due to mounting space restrictions, as well as restrictions with regard to front-to-rear weight distribution and lowering the center of gravity. In addition, in consideration of heat generated by the battery due to charging/discharging, a cooling system may be incorporated into the battery. Patent Document <NUM>, described below, discloses a vehicle in which a battery pack incorporating a liquid cooling system is mounted in the floor of the vehicle cabin.

Patent Document <NUM> discloses a vehicle mounted structure of a battery pack mounted to a floor of a vehicle cabin, comprising:.

Impact from below may be input to a battery pack mounted in the floor of a vehicle cabin, due to unevenness of the road surface, or the like. It is necessary to protect the battery pack from impact from below. In particular, cooling pipes in which coolant circulates are installed inside a battery pack incorporating a liquid cooling system, so that it is necessary to protect the cooling pipes from impact from below. Therefore, an object of the present invention is to provide a structure for mounting a battery pack in a vehicle that can reliably protect a battery pack mounted in the floor of a vehicle cabin.

The above object is solved by a vehicle mounted structure defined in the appended independent claim. Further advantageous effects can be achieved by preferred embodiments defined in the appended dependent claims.

The present invention provides a vehicle mounted structure of a battery pack mounted to the floor of a vehicle cabin. The structure comprises:.

By means of the feature described above, it is possible to provide a mounting structure for mounting a battery pack in a vehicle that can reliably protect a battery pack mounted in the floor of a vehicle cabin.

A mounting structure for mounting a battery pack in a vehicle according to the embodiment will be described below with reference to the drawings.

A battery pack <NUM> is mounted in a floor of a vehicle cabin. The battery pack <NUM> occupies almost all of the vehicle cabin floor. As shown in <FIG>, the mounting structure for mounting the battery pack <NUM> on the vehicle according to the present embodiment has, in addition to the battery pack <NUM>, a metal underguard <NUM> attached to the battery pack <NUM> from below, and a resin under cover <NUM> attached to the underguard <NUM> from below.

The battery pack <NUM> includes a housing <NUM>, an upper plate <NUM> that closes an upper opening of the housing <NUM>, a plurality of battery modules (not shown) housed inside the housing <NUM>, and various electronic devices (not shown) such as harnesses and control modules. A plurality of battery cells are housed inside each battery module. A bottom plate 10b of the housing <NUM> is formed by joining four extruded aluminum materials in the lateral direction of the vehicle (refer to <FIG>). The extruded materials are welded to each other at flanges 10f formed downwardly along the side edges thereof (refer to <FIG>). A side plate <NUM> of the housing <NUM> is also formed of an extruded aluminum material and is joined to the peripheral edge of the bottom plate 10b. The upper plate <NUM> is a press-molded metal plate.

As shown in <FIG>, a plurality of brackets are attached to the peripheral edge of the housing <NUM>. The battery pack <NUM> is fixed to a vehicle body (side sill, for example) via these brackets. The battery pack <NUM> also functions as a structural member that improves the rigidity and strength of the vehicle body. As shown in <FIG>, cooling pipes <NUM> are integrally formed with the bottom plate 10b at the time of extrusion molding, and, in the present embodiment, the cooling pipes <NUM> are embedded inside the bottom plate 10b. The cooling pipes <NUM> are formed so as to protrude downward from the bottom surface of the bottom plate 10b. <FIG> is a cross-sectional view taken along line IV-IV in <FIG> and shows only the left side of the battery pack <NUM>, but the right side is formed symmetrically. <FIG> shows the under cover <NUM>, but the under cover <NUM> is not shown in <FIG>.

As shown in <FIG>, four cooling pipes <NUM> are formed in each of the extruded materials constituting the bottom plate 10b. Each of the cooling pipes <NUM> extends in the longitudinal direction of the vehicle. The cooling pipes <NUM> are arranged substantially evenly in the lateral direction. By integrally forming the cooling pipes <NUM> (as well as the flanges 10f) with the bottom plate 10b, the strength and rigidity of the bottom plate 10b are improved. The upper surface of the bottom plate 10b is flat, which is convenient for laying the battery modules described above thereon, and is convenient for increasing the contact area between the battery modules and the bottom plate 10b. In this manner, by embedding the cooling pipes <NUM> in the bottom plate 10b and making the upper surface of the bottom plate 10b flat, heat exchange between the battery modules and the coolant flowing inside the cooling pipes <NUM> can be promoted.

As shown in <FIG>, the outer sides of two extruded materials on the two sides of the four extruded materials of the bottom plate 10b respectively form a double bottom structure. Two cooling pipes <NUM> are arranged inside the double bottom structure. Coolant is circulated inside each of the cooling pipes <NUM>. The circulation of the coolant is controlled by a temperature control system (not shown). Temperature sensors are provided in the battery modules, and the like, and the temperature control system controls a circulation pump (not shown) such that the temperature of the battery modules will remain within an appropriate range, based on the detection results of the temperature sensors. Mounting holes <NUM> to which the two side edges of the underguard <NUM> are attached and mounting holes <NUM> of the under cover <NUM> are formed in the above-described double bottom structure portions of the bottom plate 10b (refer to <FIG>).

Each of the two central extruded materials of the four extruded materials of the bottom plate 10b has a bracket <NUM> in the center in the lateral direction thereof. The brackets <NUM> are also integrally formed during extrusion molding, in the same manner as the cooling pipes <NUM>. The brackets <NUM> also extend in the longitudinal direction of the vehicle. Each of the brackets <NUM> forms a closed cross section together with the bottom plate 10b. As shown in <FIG>, in each of the brackets <NUM>, five blind nuts <NUM> are spaced apart from each other and fixed by means of swaging.

The underguard <NUM> is made of aluminum and is press-molded. As shown in <FIG> and <FIG>, the underguard <NUM> has a corrugated shape in which upwardly protruding ribs (beads, embosses) <NUM> and downwardly protruding ribs <NUM> are alternately arranged in the lateral direction. That is, the upwardly protruding ribs <NUM> and the downwardly protruding ribs <NUM> extend in the longitudinal direction. The cooling pipes <NUM> of the housing <NUM> are arranged facing the downwardly protruding ribs <NUM>. In other words, in bottom surface view (or in plan view), the cooling pipes <NUM> are positioned within the bounds of the downwardly protruding ribs <NUM>. The front end portion and the rear end portion of the underguard <NUM> are each bent to form a stepped portion so as to be in contact with the battery pack <NUM>.

An upper plate 20a of the upwardly protruding ribs <NUM> and the bottom surface of the bottom plate 10b are spaced apart from each other. A lower plate 21a of the downwardly protruding ribs <NUM> and the cooling pipes <NUM> are spaced apart from each other. The distance between the lower plate 21a and the cooling pipes <NUM> is greater than the distance between the upper plate 20a and the bottom surface of the bottom plate 10b. A sloped plate <NUM> is formed between the upper plate 20a and the lower plate 21a that are adjacent to each other. Five bulges <NUM> are formed on the lower plate 21a that opposes the above-described bracket <NUM> to match the positions of the blind nuts <NUM>. Each bulge <NUM> protrudes upward in a circular shape and is in contact with the bottom surface of the bracket <NUM>.

A bolt hole 23a is formed in the center of the bulge <NUM>, and a bolt 23b, which is a fastener, is inserted into the bolt hole 23a and fastened to the blind nut <NUM>. Mounting holes <NUM> are formed on both sides of the underguard <NUM>, and the mounting holes <NUM> match the mounting holes <NUM> formed on the bottom plate 10b. Resin pins <NUM>, which are fasteners, are attached to the mounting holes <NUM> and <NUM>. In this manner, the underguard <NUM> is attached to the housing <NUM> by the bolts 23b and the resin pins <NUM>. In addition, mounting holes <NUM> of the under cover <NUM> are formed on the lower plate 21a, on which the bulges <NUM> are not formed.

The under cover <NUM> is made of resin, and, in the present embodiment, is composed of five parts, a front portion 3f, a rear portion 3r, a central portion 3c, and a pair of side portions <NUM>, as shown in <FIG>. These five parts are attached to the underguard <NUM>, thereby forming one under cover <NUM>. A plurality of bulges <NUM> are formed on the under cover <NUM>. Each bulge <NUM> protrudes upward in a circular shape and is in contact with the bottom surface (lower plate 21a) of the underguard <NUM>. A mounting hole 31a (refer to <FIG>) is formed in the center of each bulge <NUM>. The mounting holes 31a match the mounting holes <NUM> formed on the bottom plate 10b or the mounting holes <NUM> formed on the underguard <NUM>. The resin pin <NUM>, which is a fastener, is attached to the mounting hole 31a and the mounting hole <NUM><NUM>. In this manner, the under cover <NUM> is attached to the underguard <NUM> by the resin pins <NUM>.

The main purpose of the under cover <NUM> is to protect the battery pack <NUM> from water, mud, and the like. On the other hand, the main purpose of the underguard <NUM> is to protect the battery pack <NUM> from impact from below. A sound-absorbing material may be attached to the upper surface of the under cover <NUM>. Alternatively, a resin sponge or felt may be press-molded to form the under cover <NUM>. The under cover <NUM> press-molded in this manner itself has sound-absorbing qualities. In the present embodiment, the front portion 3f, the rear portion 3r, and the side portions <NUM> are formed by means of injection molding, and the central portion 3c is formed by means of the above-described press-molding.

Next, shock absorption by the underguard <NUM> when impact is input to the battery pack <NUM> from below due to unevenness or obstacles on the road surface will be described with reference to <FIG> show the portion in the vicinity of where impact was input. Although the under cover <NUM> is not shown in <FIG>, impact from below is first absorbed by the under cover <NUM>. Mild impact can be absorbed by elastic deformation or plastic deformation of the under cover <NUM>. Moderate impact that cannot be fully absorbed by the deformation of the under cover <NUM> is absorbed as a result of the resin pins <NUM> that fix the under cover <NUM> being pulled out or being broken. That is, the resin pins (fasteners) fixing the under cover <NUM> can function as fuses.

Severe impact that cannot be fully absorbed by the under cover <NUM> is absorbed by the underguard <NUM>. In such a case, the impact is input to the underguard <NUM> via the under cover <NUM>. As can be understood from the comparison between <FIG> and <FIG>, first, the bulges <NUM>, which are the fixing points of the underguard <NUM>, are deformed so as to be crushed, thereby absorbing impact. Because the underguard <NUM> of the present embodiment is made of metal, the deformation of the underguard <NUM> can effectively absorb the impact energy. The deformation shown in <FIG> occurs because the bottom plate 10b and the upper plate 20a of the upwardly protruding ribs <NUM> are spaced apart from each other. In addition, as shown in <FIG>, the cooling pipes <NUM> are arranged facing the downwardly protruding ribs <NUM>, and because the cooling pipes <NUM> and the lower plate 21a of the downwardly protruding ribs <NUM> are spaced apart from each other, the underguard <NUM> does not come in contact with the cooling pipes <NUM> even in the state shown in <FIG>.

The deformation shown in <FIG> continues until the upper plate 20a comes in contact with the bottom plate 10b. Subsequently, as can be understood from the comparison between <FIG> and <FIG>, the sloped plate <NUM> and the lower plate 21a of the downwardly protruding ribs <NUM> on the outside of the bulges <NUM> deform, thereby absorbing the impact. At this time, because the upper plate 20a is already in contact with the bottom plate 10b, the deformed lower plate 21a or the sloped plate <NUM> is not likely to come in contact with the cooling pipes <NUM>. Even if the lower plate 21a or the sloped plate <NUM> comes in contact with the cooling pipes <NUM>, the lower plate 21a or the sloped plate <NUM> deforms, rather than the cooling pipes <NUM>. As shown in <FIG>, a deformation similar to this deformation can occur in the flanges 10f, which serve as the joint portions of the extruded materials constituting the bottom plate 10b (refer to <FIG>).

If the deformation shown in <FIG> still cannot fully absorb the impact, as can be understood from the comparison between <FIG> and <FIG>, the impact acts on the bolt hole 23a of the underguard <NUM> and deforms (breaks) the periphery of the bolt hole 23a. This deformation (damage) around the bolt hole 23a further absorbs the impact. The probability that all of the bolt holes 23a will break at the same time is extremely low, which prevents the underguard <NUM> from falling off of the vehicle. As a result of the shock absorption by means of the deformation of the underguard <NUM> as shown in <FIG>, the bottom plate 10b, that is, the battery pack <NUM> is protected from the impact. Because the bracket <NUM> has a closed cross section, the bracket <NUM> exhibits sufficient strength and rigidity against the deformation of the underguard <NUM> shown in <FIG>.

Unevenness and foreign objects on the road surface may directly hit the bulges <NUM>. In this case, in addition to the deformation described above, it is conceivable that the head portion of the bolt 23b may break, or that the blind nut <NUM> may be pulled out and the bracket <NUM> damaged. Even in such a case, impact is absorbed by means of the breakage of the bolt 23b and the pulling out of the blind nut <NUM>. In the case of the blind nut <NUM> being pulled out, the bracket <NUM> will be damaged but damage of the battery pack <NUM> will be limited to the bracket <NUM>, and the function of the battery pack <NUM> will not be impaired. The cooling pipes <NUM> will also be protected by the underguard <NUM>.

Here, a case was described in which the deformation of the underguard <NUM> proceeds from the state shown in <FIG> to the state shown in <FIG>. However, there are cases in which all of the impact can be absorbed in the state shown in <FIG> or <FIG>. In addition, while it depends on the position where the impact is input, impact is also absorbed as a result of the resin pins <NUM> (fasteners), which fix the underguard <NUM>, being pulled out or broken. However, deformation around the bolts (fasteners) 23b of the underguard <NUM> shown in <FIG> can absorb more impact than the resin pins (fasteners) <NUM> being pulled out or broken.

By means of the present embodiment, the underguard <NUM> is attached to the housing <NUM> of the battery pack <NUM>, with the upper plate 20a of the upwardly protruding ribs <NUM> being spaced apart from the bottom surface of the bottom plate 10b. As a result, as shown in <FIG>, due to the deformation (deformation <NUM>) of the underguard <NUM> up to where the upper plate 20a comes in contact with the bottom surface of the bottom plate 10b, impact from below is absorbed by the deformation of the underguard <NUM>, thereby protecting the battery pack.

Here, because the cooling pipes <NUM> are arranged facing the downwardly protruding ribs <NUM> of the underguard <NUM>, contact between the cooling pipes <NUM> and the underguard <NUM> (downwardly protruding ribs <NUM>) is prevented when the underguard <NUM> deforms, thereby protecting the cooling pipes <NUM>. That is, by means of the present embodiment, the function of the cooling system of the battery pack <NUM> can also be protected. (The cooling pipes <NUM> can also be protected by means of the modified example of the arrangement of the cooling pipes <NUM>, described further below.

In addition, by means of the present embodiment, the cooling pipes <NUM> protrude downward from the bottom surface of the bottom plate 10b, which facilitates mounting of the battery modules inside the housing <NUM>, and heat exchange with the coolant inside the cooling pipes <NUM> can be carried out efficiently. Here, if the cooling pipes <NUM> protrude downward from the bottom surface of the bottom plate 10b, it becomes difficult to protect the cooling pipes <NUM> from impact from below. However, because the cooling pipes <NUM>, which protrude downward, are spaced apart from the lower plate 21a of the downwardly protruding ribs <NUM>, contact between the deformed underguard <NUM> (lower plate 21a) and the cooling pipes <NUM> can be effectively avoided. That is, even the battery pack <NUM> provided with the cooling pipes <NUM> protruding downward can be reliably protected by the underguard <NUM>.

In addition, by means of the present embodiment, the bracket <NUM> forming a closed cross section together with the bottom plate 10b protrude downward from the bottom surface of the bottom plate 10b, and the underguard <NUM> (bulges <NUM>) is fixed to the bracket <NUM> by fasteners (bolts 23b). That is, the bottom plate 10b and the fasteners of the underguard <NUM> to the housing <NUM> (bracket <NUM>) of the battery pack <NUM> are spaced apart from each other by the height of the downwardly protruding bracket <NUM>. By means of this configuration, in addition to "deformation <NUM>" described above, as shown in <FIG>, impact from below can be absorbed by the deformation of the underguard <NUM> to thereby protect the battery pack, by means of the following deformations <NUM> and <NUM> of the underguard <NUM>. (Deformation <NUM>) Deformation of the underguard <NUM> in the range from the upper plate 20a of the upwardly protruding ribs <NUM> to the lower plate 21a of the downwardly protruding ribs <NUM>. (Deformation <NUM>) Deformation accompanied by damages in the vicinity of the fastener (bolt holes 23a) of the underguard <NUM> to the housing <NUM>.

Furthermore, by means of the present embodiment, the resin under cover <NUM> is attached to the bottom surface of the underguard <NUM>. For this reason, the battery pack <NUM> (and the underguard <NUM>) can be protected from rain and mud, and it is also possible to insulate (or absorb) airborne sounds coming from below the floor. In addition, because impact from below can also be absorbed by means of deformation of the under cover <NUM>, light impact can be fully absorbed by the under cover <NUM> without deforming the underguard <NUM>. In addition, the under cover <NUM> is fixed to the bottom surface of the underguard <NUM> by fasteners (resin pins <NUM>). The fasteners (resin pins <NUM>) function as fuses, so that impact from below can also be absorbed by means of damage to the fasteners (resin pins <NUM>).

The present invention is not limited to the embodiment described above. The cooling pipes <NUM> are arranged on the bottom surface side of the bottom plate 10b, but may be arranged on the upper surface side (inside the housing <NUM>). The thickness of the bottom plate 10b may be made greater than the inner diameter of the cooling pipes <NUM>, and the cooling pipes <NUM> may be arranged inside the thickness of the bottom plate 10b (between the bottom surface and the upper surface of the bottom plate 10b). The cooling pipes <NUM> are embedded in the bottom plate 10b in the above-described embodiment, but may be separately formed and attached to the surface (bottom surface or upper surface) of the bottom plate 10b.

Claim 1:
A vehicle mounted structure of a battery pack (<NUM>) mounted to a floor of a vehicle cabin, comprising:
a bottom plate (10b) of a housing (<NUM>) of the battery pack; and
a plate-shaped underguard (<NUM>) provided below the bottom plate (10b),
the underguard (<NUM>) having upwardly protruding ribs and downwardly protruding ribs that are alternately arranged;
characterized by
cooling pipes (<NUM>) provided inside or on a surface of the bottom plate (10b) for circulating coolant;
wherein
the cooling pipes (<NUM>) are arranged to face the downwardly protruding ribs, and
the underguard (<NUM>) is attached to the housing (<NUM>) such that an upper plate of the upwardly protruding ribs and a bottom surface of the bottom plate (10b) are spaced apart from each other.