Patent Description:
Development of electrically driven vehicles such as an electric vehicle that uses a motor as a drive power source in place of an engine, i.e., an internal combustion engine, and a hybrid vehicle that uses both the internal combustion engine and motor, has progressed in the prior art in view of environmental impact reduction. These electrically driven vehicles each, in particular, have a drive battery mounted thereon to drive the motor, and, with the battery supplying electric power to the motor, power necessary to run the vehicle is obtained. In recent years, development of such electrically driven vehicles has also progressed in the field of commercial vehicles such as trucks. For example, PTL <NUM> discloses a retention structure with which a drive battery pack is retained at a ladder frame of an electric truck.

<CIT> shows a vehicle battery pack support device for suspending a battery pack at a side rail of a ladder frame of a vehicle having a frame-side bracket secured, by bolts, to an outer side face of the side rail at a plurality of bolt fastening parts thereof arrayed in a grid arrangement, and having a spacer interposed between the outer side face of the side rail and the frame-side bracket. <CIT> discloses a battery pack fixing structure disposed below a rear seat, wherein the battery pack comprises: a first fixing portion positioned at a front lower portion of the battery pack and fixed to a front cross member; a rear upper portion And a second fixing portion which is fixed to the rear cross member and is fixed to the rear cross member, wherein a cushioning material is interposed between the battery pack and the body floor. <CIT> discloses a battery pack with unit cells stored in an external case, a resin group fills there, and the external case is supported with an external elastic body. The resin group and the external elastic body can sufficiently attenuate the vibration and transmit it to the unit cells and the like. This constitution can be regarded as a mass spring model of two freedom degrees or more and each mass, a spring constant and damping of each elastic body are controlled so that resonant peaks can be deviated from <NUM> or less, or a range of vibration produced in an automobile. <CIT> discloses a battery fixing device, the battery fixing device comprises: a receiving member on which two batteries are to be parallelly placed side by side; a retainer which is disposed so as to partially hang between the two batteries, and which is locked on the opposing shoulder sections of the respective two batteries; a rod of which the base end is fixed to the receiving member and the distal end penetrates both ends of the retainer; and a nut to be screwed onto the distal end of the rod. Further, the rod penetrates the retainer within a range where the two batteries are opposed to each other.

An electric truck such as the one mentioned above has a larger vehicle weight than a passenger car, hence, the electric truck has to have a large, high-capacity battery pack mounted thereon in order to secure a sufficient travel distance. When the battery pack has a length greater in the vehicle width direction than that of the ladder frame, the battery pack is suspended at the ladder frame by a support device connected to a surface on the outer side of the ladder frame of the vehicle in the vehicle width direction.

However, in such a support device, in order to secure sufficient reliability in supporting a large battery pack, the support device has to be composed of robust components, and this may lead to an increase in weight. Moreover, the distance between side rails of the ladder frame, at which the battery pack is suspended, differs depending on vehicle class, hence, if the support device is to be designed and produced for each vehicle class, the cost of the support device may increase accordingly.

The present invention has been made in view of the circumstance, and an object thereof is to provide a vehicle battery pack support device that is applicable to various vehicle classes and allows weight reduction and cost reduction.

The vehicle battery pack support device according to the present invention is a vehicle battery pack support device for suspending a battery pack at a side rail constituting a ladder frame of a vehicle, and includes: a frame-side bracket secured, by bolts, to an outer side face of the side rail at a plurality of bolt fastening parts arrayed in a grid arrangement; an elastic coupling part elastically coupling the battery pack and the frame-side bracket; and a spacer interposed between the outer side face of the side rail and the frame-side bracket. The spacer includes lower extensions in the vehicle height direction, the lower extensions extending downward further than the bottom surface of the side rails in the vehicle height direction.

The vehicle battery pack support device suspends a battery pack at the ladder frame of a vehicle using the frame-side bracket, which is connected to an outer side face of the side rail, and the elastic coupling part. With the spacer, which has a width corresponding to a spacing distance between the side rail and the frame-side bracket, being interposed therebetween, no change in configuration is needed other than that in the spacer even when there are variations in distance between the side rails, depending vehicle classes.

According to one embodiment of the invention the spacer is provided with a plurality of columnar members that support bolts, which are fixed to the side rail, around bolt through holes the bolts pass through, and these columnar members are formed as a unified one piece by connecting parts. Therefore, as compared to spacers individually provided to the bolts, process of fixing spacers to each of the side rails can be implemented simpler. Moreover, since the columnar members and connecting parts of the spacer ensure the connection strength with which the heavy battery pack is suspended at the ladder frame, parts other than these can be formed as hollow parts. Accordingly, the vehicle battery pack support device according to the present invention is applicable to various classes of vehicles and allows weight reduction and cost reduction.

Moreover, the drawings used for the explanation of the embodiment all provide diagrammatic illustrations of constituent elements with partial exaggeration, enlargement, diminution, omission and the like for the sake of better understanding, hence they may not necessarily precisely represent the scales, shapes and the like of the constituent elements.

<FIG> is a schematic top plan view illustrating an entire configuration of a vehicle <NUM> on which a vehicle battery pack support device according to the present invention is mounted. As illustrated in <FIG>, the vehicle <NUM> according to this embodiment is an electric truck including a ladder frame <NUM>, a cab <NUM>, a cargo box <NUM>, a wheel mechanism <NUM>, a drive unit <NUM>, a drive power supply part <NUM>, a battery pack <NUM>, and a plurality of support devices <NUM> as "vehicle battery pack support devices". Note, <FIG> illustrates the vehicle <NUM> in top plan view as viewed from above and seen through the cab <NUM> and cargo box <NUM>.

Although the vehicle <NUM> in this embodiment is assumed to be an electric car equipped with an electric motor (motor <NUM> to be described later) as the drive power source, the vehicle may be a hybrid car that additionally includes an engine. Moreover, the vehicle <NUM> is not limited to an electric truck but may be another commercial vehicle equipped with a battery that drives the vehicle, such as an electric garbage truck.

The ladder frame <NUM> has side rails <NUM> and a plurality of cross members <NUM>. The side rails <NUM> extend along a front to back direction X of the vehicle <NUM> and include a left side rail <NUM> and a right side rail 11R that are arranged parallel to each other side by side in the vehicle width direction Y. The plurality of cross members <NUM> connect the left side rail <NUM> and right side rail 11R. Namely, the ladder frame <NUM> configures a frame known as a ladder type. The ladder frame <NUM> supports the cab <NUM>, cargo box <NUM>, drive unit <NUM>, drive power supply part <NUM>, battery pack <NUM>, and other heavy goods loaded on the vehicle <NUM>.

The cab <NUM> is a structure including a driver's seat (not shown) that is provided above a front part of the ladder frame <NUM>. The cargo box <NUM>, on the other hand, is a structure loaded with cargo or the like transported by the vehicle <NUM>, and provided above a rear part of the ladder frame <NUM>.

The wheel mechanism <NUM> is composed of left and right front wheels <NUM> positioned in the front part of the vehicle, a front axle <NUM> that is the axle of the two front wheels <NUM>, two rear wheels <NUM> on left and right positioned in the rear part of the vehicle, and a rear axle <NUM> that is the axle of the rear wheels <NUM>. In the vehicle <NUM> according to this embodiment, the drive force is transmitted such that the rear wheels <NUM> function as drive wheels to cause the vehicle <NUM> to run. The wheel mechanism <NUM> is suspended at the ladder frame <NUM> via a suspension mechanism (not shown) and supports the weight of the vehicle <NUM>.

The drive unit <NUM> has a motor <NUM>, a reduction gear <NUM>, and a differential gear <NUM>. The motor <NUM> generates a drive force necessary for causing the vehicle <NUM> to run, with an alternating current supplied from the drive power supply part <NUM> to be described later. The reduction gear <NUM> includes a plurality of gears (not shown), and outputs the rotational torque input from the motor <NUM> to the differential gear <NUM> at a reduced rate. The differential gear <NUM> distributes the power input from the reduction gear <NUM> to left and right rear wheels <NUM>. Namely, the drive unit <NUM> transmits the drive power to the rear axle <NUM> by reducing the drive torque from the motor <NUM> to a rotation speed suitable for the vehicle to run via the reduction gear <NUM> and differential gear <NUM>. The drive unit <NUM> thus allows the rear wheels <NUM> to rotate via the rear axle <NUM> to enable the vehicle <NUM> to run.

The drive power supply part <NUM> is a device known as an inverter, which delivers power from the battery pack <NUM> to the motor <NUM> by converting a direct current to an alternating current, and controls the rotational speed of the motor <NUM> in accordance with the operation of the acceleration pedal of the vehicle <NUM>.

The battery pack <NUM> is a rechargeable battery that supplies electric power to the motor <NUM> as an energy source for causing the vehicle <NUM> to run. The battery pack <NUM> includes a plurality of relatively large and high-capacity battery modules (not shown) inside to store electric power required for the vehicle <NUM>. Here, the battery pack <NUM> in this embodiment is arranged to extend over the space between the left side rail <NUM> and the right side rail 11R and below the side rails <NUM>, and has an inverted T-shaped cross section in a plane vertical to the front to back direction of the vehicle X.

The support device <NUM> is a connecting member for suspending the battery pack <NUM> at the ladder frame <NUM>, as will be described later in detail. In this embodiment, three each support devices <NUM> (total of six) are provided on both sides in the vehicle width direction Y of the ladder frame <NUM>. Note, the number of the support devices <NUM> may be changed as suited in accordance with the weight and size of the battery pack <NUM>.

<FIG> is a perspective view illustrating a configuration and a form of connection of the support device <NUM> that connects the side rail <NUM> and the battery pack <NUM>. <FIG>, more particularly, is a perspective view of one support device <NUM> connected to the left side rail <NUM> as viewed diagonally from front left of the vehicle <NUM>.

Here, the side rail <NUM> has a shape in which a web 11w forming a flat surface vertical to the vehicle width direction Y is continuous with two flanges 11f forming flat surfaces vertical to a vehicle height direction Z. The web 11w includes bolt fastening parts <NUM> formed as through holes in a grid arrangement for allowing bolts 11B to be fastened to suspend various heavy goods at the vehicle <NUM>.

The support device <NUM> includes a frame-side bracket <NUM>, a battery-side bracket <NUM>, an elastic coupling part <NUM>, and a spacer <NUM>.

The frame-side bracket <NUM> is a metal member to be connected to an outer side face of the side rail <NUM>, i.e., the web 11w, with a plurality of bolts 11B. Namely, the frame-side bracket <NUM> is connected to the outer side face of the side rail <NUM> via the spacer <NUM> in a flat surface part vertical to the vehicle width direction Y. The frame-side bracket <NUM> is also connected to the elastic coupling part <NUM> in a flat surface part vertical to the vehicle height direction Z.

The battery-side bracket <NUM> is a metal member connected to an outer side face in the vehicle width direction Y of the battery pack <NUM> for suspending the battery pack <NUM> on the outer side of the side rail <NUM> in the vehicle width direction Y.

The elastic coupling part <NUM> elastically connects vertically the frame-side bracket <NUM> and the battery-side bracket <NUM> in the vehicle height direction Z and includes a part known as a rubber bushing that absorbs the stress caused by the relative displacement therebetween.

The spacer <NUM> is a metal member to be interposed between the side rail <NUM> and the frame-side bracket <NUM> when their connecting surfaces are spaced apart. Therefore, if the side rail <NUM> and the frame-side bracket <NUM> are not spaced apart, the spacer <NUM> is not necessary.

As described above, the battery pack <NUM> in the vehicle <NUM> of this embodiment is suspended at the side rails <NUM> by the support devices <NUM> including the battery-side bracket <NUM>, elastic coupling part <NUM>, frame-side bracket <NUM>, and spacer <NUM>. Therefore, even when the side rails <NUM> are subjected to stresses caused by torsion and deflection as the vehicle <NUM> runs, the elastic coupling part <NUM> can reduce the risk of such stresses being transmitted to the battery pack <NUM> with its dampening effect.

<FIG> is a perspective view indicating the structure of the spacer <NUM> in the support device <NUM>. More particularly, <FIG> illustrates the full view of the spacer <NUM>, which is only partly visible in <FIG>.

The spacer <NUM> includes a plurality of columnar members <NUM>, a plurality of connecting parts <NUM>, and a plurality of lower extensions <NUM>, with these components being integrally formed by aluminum extrusion, for example.

The plurality of columnar members <NUM> are aligned in the X-Z plane at intervals corresponding to the intervals of the plurality of bolt fastening parts <NUM> formed in the web 11w of the side rail <NUM> in a grid arrangement. Here, in this embodiment, there are three columnar members <NUM> along the longitudinal direction of the vehicle X and four columnar members along the vehicle height direction Z in a matrix arrangement. The number and arrangement of the plurality of columnar members are not limited to this and may be changed suitably in accordance with various conditions.

The plurality of connecting parts <NUM> are connecting portions that allow for integral formation of the plurality of columnar members <NUM>, and each of the connecting parts <NUM> connects two columnar members <NUM> adjacent each other in the longitudinal direction of the vehicle X and in the vehicle height direction Z. Note, the plurality of connecting parts <NUM> only need to connect all the columnar members <NUM> of the spacer <NUM> together, and two adjacent columnar members <NUM> need not necessarily be connected directly. Accordingly, there are formed hollow parts <NUM> in the spacer <NUM> among the plurality of connecting parts <NUM>.

The lower extensions <NUM> are parts that extend downward in the vehicle height direction Z from the columnar members <NUM> arranged lowermost in the vehicle height direction Z and define the height of the bottom surface of the spacer <NUM>. The effects of the lower extensions <NUM> will be described later.

The plurality of columnar members <NUM> each include a circular bolt end surface <NUM> on the end face in the vehicle width direction Y, and a bolt through hole <NUM> at the center of the bolt end surface <NUM> extending through in the vehicle width direction Y. This allows the spacer <NUM> to be sandwiched between the side rail <NUM> and the frame-side bracket <NUM> from both sides in the vehicle width direction Y, with bolts 11B passing through the bolt through holes <NUM> integrally fixing them together.

Since the spacer <NUM> is formed by aluminum extrusion, for example, as mentioned above, the width W in the vehicle width direction Y can be readily adjusted in accordance with the spacing between the side rail <NUM> and the frame-side bracket <NUM>. Even when there are variations in this spacing, the width W can be determined by the position of cutting the extrusion-molded aluminum, which allows for common use of metal molds for forming spacers <NUM>.

The spacer <NUM>, by supporting the bolts 11B between the side rail <NUM> and the frame-side bracket <NUM>, helps increase the reliability to withstand the stress applied to the bolts 11B caused by the weight of the battery pack <NUM>. Moreover, parts of the spacer <NUM> that are redundant in terms of improvement of reliability are formed as hollow parts <NUM>, so that a weight reduction can be achieved.

<FIG> is a schematic rear view illustrating a form of connection of the support device <NUM> that connects the side rail <NUM> and the battery pack <NUM>. More particularly, <FIG> presents a diagrammatic plan view of the battery pack <NUM> suspended at the side rails <NUM> by the support devices <NUM> as viewed from the back in the longitudinal direction of the vehicle X.

The battery pack <NUM> mounted on the vehicle <NUM> is suspended at the side rails <NUM> using the battery-side brackets <NUM>, elastic coupling parts <NUM>, frame-side brackets <NUM>, and spacers <NUM>, as described above, on both sides in the vehicle width direction Y. Note, the spacing between the left side rail <NUM> and the right side rail 11R of the side rails <NUM> differs depending on the class of the vehicle <NUM>. Therefore, the support device <NUM> adjusts this spacing by means of the width W in the vehicle width direction Y of the spacer <NUM>.

Here, the frame-side bracket <NUM> is connected to the side rail <NUM> in the vehicle width direction Y via the spacer <NUM> with bolts 11B, and connected to the elastic coupling part <NUM> below in the vehicle height direction Z. Therefore, stress applied to the spacer <NUM> and the frame-side bracket <NUM> concentrates on the shortest path between the side rail <NUM> and the elastic coupling part <NUM>.

The plurality of columnar members <NUM> described above of the spacer <NUM> are connected to the outer side face of the side rail <NUM> such as to correspond to the plurality of bolt fastening parts <NUM> formed in the web 11w of the side rail <NUM>. Here, since the lower extensions <NUM> are formed below the plurality of columnar members <NUM> in the vehicle height direction Z, the lower extensions <NUM> of the spacer <NUM> extend downward further than the bottom surface of the side rails <NUM> in the vehicle height direction Z. Therefore, the lower extensions <NUM> provided in parts where stress concentrates allow the spacer <NUM> to have an increased durability against the stress.

As described above, the support device <NUM> according to the present invention is provided with a spacer <NUM> having a width W in accordance with the spacing distance between the outer side face of the side rail <NUM> and the frame-side bracket <NUM> for suspending the battery pack <NUM> at the side rails <NUM> of the vehicle. Therefore, even when there are variations in the spacing between the left side rail <NUM> and the right side rail 11R for various vehicle classes, it is not necessary to design and produce support devices <NUM> by taking the variations into account, hence costs can be reduced.

Moreover, the spacer <NUM> of the support device <NUM> according to the present invention includes a plurality of columnar members <NUM> connected together by connecting parts <NUM>, while redundant parts in terms of the support of weight of the battery pack <NUM> are formed as hollow parts <NUM>, which allows weight reduction and cost reduction.

Moreover, the spacer <NUM> of the support device <NUM> according to the present invention is formed by extrusion molding, for example, and this allows a metal mold to be used in common for formation of a variety of widths W, enabling a reduction in design and production costs. Accordingly, the vehicle battery pack support device <NUM> according to the present invention is applicable to various classes of vehicles and allows weight reduction and cost reduction.

Claim 1:
A vehicle battery pack support device (<NUM>) for suspending a battery pack (<NUM>) at a side rail (<NUM>) constituting a ladder frame (<NUM>) of a vehicle (<NUM>), the device (<NUM>) comprising:
a frame-side bracket (<NUM>) spaced apart to an outer side face of the rail (<NUM>), and secured, by bolts (11B), to the outer side face of the side rail (<NUM>) at a plurality of bolt fastening parts (<NUM>) thereof arrayed in a grid arrangement; and
a spacer (<NUM>) interposed between the outer side face of the side rail (<NUM>) and the frame-side bracket (<NUM>), characterized in that
the vehicle battery pack support device further comprises
an elastic coupling part (<NUM>) elastically coupling the battery pack (<NUM>) and the frame-side bracket (<NUM>); and
the spacer (<NUM>) including a plurality of columnar members (<NUM>) corresponding to the plurality of bolt fastening parts (<NUM>), a connecting part (<NUM>) connecting the plurality of columnar members (<NUM>), and lower extensions (<NUM>), the lower extensions (<NUM>) extending downward further than the bottom surface of the side rails (<NUM>) in the vehicle height direction (Z).