Patent Description:
In recent years, in the field of a commercial vehicle having a ladder frame structure such as a truck and a pick-up truck, effort is being made to develop an electric vehicle from which an internal combustion engine has been abolished but which in turn uses only an electric motor as a driving source from the viewpoint of reducing environmental loading. A known driving unit to be mounted on such an electric vehicle is exemplified by a driving unit for a vehicle which unit includes an electric motor and a power transmission mechanism such as a transmission device including multiple gears and is configured to transmit the driving force of the electric motor to the differential gear connected to the driving wheels (see Patent Document <NUM>).

Here, an electric truck, which has a larger vehicle weight than an ordinary electric vehicle, requires greater driving torque than the electric vehicle, and consequently requires a motor supporting bracket having a high rigidity to mount a driving motor to the vehicle body. In such a motor supporting bracket, since a large load can be input into the left- and right-bending direction (vehicle width direction), the material for the bracket is demanded to be thickened. On the other hand, from the viewpoint of desiring to ensure reliability without increasing the weight by wall-thickening, one of the solutions is to increase the cross-sectional secondary moment by forming a rib (plate-like reinforcing structure) on the surface of the motor supporting bracket.

However, forming the above rib increases the size of the motor supporting bracket by a dimension of the rib and, for example, the size of the motor supporting bracket in the vehicle longitudinal direction is increased. In addition to this, components such as a driving unit and related device (E-Axle related equipment) to the driving unit may be placed around the motor supporting bracket. Therefore, it is sometimes difficult to form the ribs that can avoid interference between the motor supporting bracket and such components.

With the problems in view, the object of the present invention is to provide an electric vehicle in which a structure for supporting a driving unit on the electric vehicle can satisfy a high-rigidity requirement without hindering the mountability and the degree of freedom of layout of other components.

The present invention has been made in order to solve at least part of the above problem, and can be achieved in the form of the following embodiment or application example.

As described above, the motor housing is coupled to the ladder frame by the first coupler part and the end part of the leaf spring is coupled to the ladder frame by the second coupler part having the rib-shaped portion. By integrating the first coupler part and the second coupler part and using the rib-shape provided as a leaf spring supporting bracket (second coupler part) also for a motor supporting bracket (first coupler part), the motor supporting bracket can be reinforced without increasing the size thereof and also increase its rigidity. Further, since the entire shape of the bracket including the first coupler part and the second coupler part is made compact in size, the leaf spring supporting bracket and the motor supporting bracket less interfere with other neighboring components in a rear axle area, which requires the arrangement of E-Axle related components and wiring, so that the mountability and the degree of freedom of layout of the components, the wiring, and pipes can be enhanced.

(<NUM>) In electric vehicle according to the present application example, in the above (<NUM>), the first coupling part may include a plate member attached to a web outer face of a side rail of the ladder frame, and a bracket part that extends downward from a flange lower face of the side rail and that is connected to the motor housing. This ensures the contact area with the web of the side rail and causes the first coupler part to be coupled to the motor housing under the lower face of the flange of the side rail. Accordingly, this makes the bracket including the first coupler part and the second coupler part to be strongly fixed to the side rail and further less likely to interfere with other neighboring components.

(<NUM>) In electric vehicle according to the present application example, in the above (<NUM>), the first coupling part further may include a pair of the plate members; and the rib-shaped portion may be sandwiched between the pair of the plate members. This makes the rib-shaped portion to be strongly fixed to the web outer face of the side rail, so that the stiffness of the first coupler part and the second coupler part is further enhanced.

(<NUM>) In electric vehicle according to the present application example embodiment, in any of the above-described (<NUM>) to (<NUM>), a position where the bracket member is coupled to the motor housing in a vehicle longitudinal may be substantially the same as a position where the rib-shaped portion is coupled to the leaf spring. This further enhances the stiffness of the first coupler part and the second coupler part.

(<NUM>) The electric vehicle according to the present application example may include a pair of planer portions spaced apart in a vehicle longitudinal direction and a connecting part that connects the planer portions with each other, in any one of the above (<NUM>) to (<NUM>). This further increases the stiffness of the rib-shaped portion, and the rigidity of first coupler part and second coupler part is further enhanced.

In the above electric vehicle (<NUM>), one of the planar portions may be connected to one of the pair of plate members, and the other of the planar portions may be connected to the other of the pair of plate members. Consequently, each of the pair of plate members is reinforced by one of the pair of planar portions so that the stiffness of the first coupler part and the second coupler part is further enhanced.

(<NUM>) In electric vehicle according to the present application example, in any one of the above-mentioned (<NUM>) to (<NUM>), the first coupling part may include a second rib-shaped portion formed into a shape protruding outward in the vehicle width direction. This further increases the stiffness of the bracket member of the first coupler part and this further enhances the stiffness of the first coupler part and the second coupler part.

According to the electric vehicle of the present application example, it is possible to provide an electric vehicle in which a structure for supporting a driving unit on the electric vehicle can satisfy a high-rigidity requirement without impairing the mountability of other components.

Hereinafter, description will now be made in relation to an electric vehicle <NUM> as an embodiment (application example) with reference to the accompanying drawings. <FIG>, <FIG>, and <FIG> are diagrams for explaining the structure of the electric vehicle <NUM> according to the present application example. The directions of front/rear, left/right, and up/down in the drawings are defined on the basis of the driver of the electric vehicle <NUM>. As shown in <FIG>, this electric vehicle <NUM> is an electric truck of the type in which the body is supported by a ladder frame <NUM> (chassis frame). The ladder frame <NUM> is a frame member formed into a ladder shape. A driving unit <NUM> (electric power-train), a cab <NUM>, a cargo space <NUM>, driving wheels <NUM>, and others of the electric vehicle <NUM> are attached to the ladder frame <NUM>.

The ladder frame <NUM> is provided with side rails <NUM> extending in the longitudinal direction (vehicle length direction) and cross members extending in the vehicle width direction (lateral direction). A pair of side rails <NUM> are spaced apart in the vehicle width direction. The cross members are joined to the left and right side rails <NUM> at a distance from one another in the longitudinal direction. The positions at which cross members are disposed are set in accordance with the components mounted on the ladder frame <NUM> and the load distribution. The cross-sectional shape of the side rail <NUM> is, for example, a channel shape. Each side rail <NUM> illustrated in <FIG> is of a channel shape having a C-shaped (U-shaped) cross-section, and is formed of a planar web 2A normal of which is arranged so as to face the vehicle width direction and flanges 2B which extend inward the vehicle width direction from the upper and lower ends of the web 2A.

The driving unit <NUM> is an electric power-train (electric traction unit) to drive the electric vehicle <NUM>. This driving unit <NUM> includes, for example, a motor <NUM> and a transmission mechanism <NUM>. The motor <NUM> is an electric motor that generates driving force to be transmitted to the axle <NUM> of the driving wheels <NUM> by consuming electric power and that is accommodated in the motor housing <NUM>. The electric power consumed by the motor <NUM> is stored in a non-illustrated battery. Furthermore, the transmission mechanism <NUM> shifts the rotational driving force transmitted from the motor <NUM>, and includes, multiple gears exemplified by a reduction gear and a gear mechanism for speed change. The driving force generated in the motor <NUM> is transmitted through transmission mechanism <NUM> to the differential gear (differential device) to which axle <NUM> is connected, so that the electric vehicle <NUM> can be driven. In the driving unit <NUM>, the motor <NUM> is disposed on the vehicle front side nearer than the transmission mechanism <NUM>.

The axle <NUM> of the driving wheels <NUM> is suspended from the ladder frame <NUM> through a leaf spring <NUM>. The leaf spring <NUM> is a suspension spring having a structure of a bundle of several elastic strips piled on one another. This leaf spring <NUM> is formed into a shape extending in the longitudinal direction, and also curved such that the center portion in the longitudinal direction protrudes downward further than the end parts. The axle <NUM> of the driving wheels <NUM> is mounted beneath this center portion in the longitudinal direction. One end (e.g., the front end) of the leaf spring <NUM> places thereon a bush and is supported by the side rail <NUM> via an integral bracket <NUM> that is to be detailed below. In contrast, the other end (e.g., the rear end) of the leaf spring <NUM> is supported by the side rail <NUM> via a non-illustrated linkage mechanism. Any known structures can be applied to the detailed structures of the leaf spring <NUM> and the axle <NUM>.

The integral bracket <NUM> is a member for attaching the motor housing <NUM> serving as a housing on the vehicle front side of the driving unit <NUM> and the leaf spring <NUM> to the ladder frame <NUM>. <FIG> illustrates an integrated bracket <NUM> for attaching the left side of the motor housing <NUM> and the front end part of the left leaf spring <NUM> to the left side rail <NUM>. Similar integral bracket <NUM> can also be arranged on the right side rail <NUM>. In this application example, description will be made in relation to the structure of the integral brackets <NUM>, focusing on the integral bracket <NUM> attached to the left side rail <NUM>.

As shown in <FIG> and <FIG>, the integral bracket <NUM> are provided with a first coupler part <NUM> and a second coupler part <NUM>. The first coupler part <NUM> is a portion that couples the side rail <NUM> of the ladder frame <NUM> to the motor housing <NUM>. The motor housing <NUM> is supported by the first coupler part <NUM> via a shaft-shaped member <NUM> (or a fastener such as a bolt, a nut, a rivet). The second coupler part <NUM> is a connecting member formed integrally with the first coupler part <NUM>, and is a portion that couples the side rail <NUM> of the ladder frame <NUM> to the end part of the leaf spring <NUM>. The end part of the leaf spring <NUM> is supported by the second coupler part <NUM> via a shaft-shaped member <NUM> (or a fastener).

The first coupler part <NUM> is provided with a plate member <NUM> and a bracket member <NUM>. The plate member <NUM> is a planar portion that is attached to the outer face of the web 2A of the side rail <NUM>. In the example shown in <FIG>, a pair of plate members <NUM> are provided, being spaced apart in the vehicle longitudinal direction, and are positioned on the same plane. The plate members <NUM> are fixed via a fastener being in a face contact with the outer face of the web 2A of the side rail <NUM>. As shown in <FIG>, multiple holes through which the fasteners are inserted are formed on each plate member <NUM>.

The bracket member <NUM> extends downward from the lower face of the flange 2B of the side rail <NUM> and is connected to the motor housing <NUM>. The bracket member <NUM> is formed of a flat part <NUM> formed in a planar shape perpendicular to the plate member <NUM> and a first wall part <NUM> and a second wall part <NUM> each formed into a planar shape perpendicular to the flat part <NUM>. The flat part <NUM> is attached to the lower face of the flange 2B of the side rail <NUM>, being in face contact with the lower face. As shown in <FIG>, multiple holes through which a fasteners are inserted are also formed on the flat part <NUM>. The flat part <NUM> is fixed to the lower face of the flange 2B via a non-illustrated fastener.

The first wall part <NUM> is a flat plate-shaped portion arranged on the same plane as the plate member <NUM>. As shown in <FIG>, the position of the first wall part <NUM> is set below the second coupler part <NUM> in a side view. The shape of the first wall part <NUM> is formed so as to extend downward from a portion sandwiched between the pair of the plate members <NUM> in a side view. A hole through which a shaft-shaped member <NUM> to be coupled to the motor housing <NUM> is inserted is provided near the lower end portion of the first wall part <NUM>.

The second wall part <NUM> is a flat-plate-shaped portion arranged more inward in the vehicle width direction than the first wall part <NUM>. The second wall part <NUM> is formed so as to extend downward from the flat part <NUM> and is arranged substantially parallel to the first wall part <NUM>. A hole through which a shaft-shaped member <NUM> to be coupled to the motor housing <NUM> is inserted is provided near the lower end portion of the second wall part <NUM>. The motor housing <NUM> is coupled to the first coupler part <NUM> via the shaft-shaped member <NUM> between the first wall part <NUM> and the second wall part <NUM>.

The second coupler part <NUM> is provided with a rib-shaped portion <NUM>. The rib-shaped portion <NUM> is a portion which protrudes outward in the vehicle width direction and is connected to end part of the leaf spring <NUM>. Rib-shaped portion <NUM>, as shown in <FIG> and <FIG>, is disposed so as to be sandwiched between the pair of plate members <NUM>. As shown in <FIG>, the outline of rib-shaped portion <NUM> can be regarded as a hook shape protruding outward from the plate member <NUM> and being arranged such that its tip directs downward. The rib-shaped portion <NUM> is provided with a pair of planar portions <NUM>, a connecting part <NUM>, a third wall part <NUM>, and a fourth wall part <NUM>.

As shown in <FIG>, the pair of planar portions <NUM> are planar portions that are spaced apart in the vehicle longitudinal direction. Each of the planar portions <NUM> is integrally formed with one of the pair of plate members <NUM>, and is arranged along the direction perpendicular to the plate members <NUM>. In other words, one of the pair of planar portions <NUM> are connected to one of the pair of plate members <NUM>, the other of the planar portion <NUM> is connected to the other of the plate members <NUM>. With this structure, the planar portion <NUM> functions as a flange that reinforces the end sides in the longitudinal direction of the plate members <NUM>, so that the stiffness of the integral bracket <NUM> is enhanced. In addition, each of the pair of plate member <NUM> is reinforced by one of the pair of planar portions <NUM>, so that the stiffness of the first coupler part <NUM> and the stiffness of second coupler part <NUM> are further enhanced.

The connecting part <NUM> is a planar member that connects between the pair of planar portions <NUM>. The orientation of the connecting part <NUM> is set, for example, substantially perpendicular to each of the pair of the planar portions <NUM>. In the example shown in <FIG>, the connecting part <NUM> is formed into a curved shape so as to conform to the hook-shaped rib-shaped portion <NUM>. For example, the portion inward of the vehicle width direction [left side in <FIG>] of the connecting part <NUM> is approximately vertically formed so as to be flush with the plate members <NUM>. Like the planar portions <NUM>, the portion outward of the vehicle width direction [right side in <FIG>] of the connecting part <NUM> protrudes outward from the plate members <NUM> and is formed such that its tip directs downward.

Like the connecting part <NUM>, the third wall part <NUM> is a planar portion that connects between the pair of planar portions <NUM> and is provided at the tip portion of the rib-shaped portion <NUM>. The orientation of the third wall part <NUM> is set substantially parallel to the plate member <NUM>. As shown in <FIG>, a hole through which the shaft-shaped member <NUM> to be connected to the leaf spring <NUM> is inserted is formed on the third wall part <NUM>. The fourth wall part <NUM> is a planar portion provided on the base end part of the rib-shaped portion <NUM>, and is arranged substantially parallel to the third wall part <NUM>. Preferably, the fourth wall part <NUM> is integrally formed with the pair of plate members <NUM> so as to be flush with the pair of plate members <NUM>. A hole through which the shaft-shaped member <NUM> is inserted is formed on the fourth wall part <NUM>. The leaf spring <NUM> is coupled to the second coupler part <NUM> via the shaft-shaped member <NUM> between the third wall part <NUM> and the fourth wall part <NUM>.

As shown in <FIG> and <FIG>, the position in vehicle longitudinal direction of the shaft-shaped member <NUM> to be connected to motor housing <NUM> is set at substantially the same position as the position in vehicle longitudinal direction of the shaft-shaped member <NUM> to be connected to the leaf spring <NUM>. In other words, the coupling position of motor housing <NUM> of the bracket member <NUM> in vehicle longitudinal direction is set to substantially the same position (in other words, near) as the coupling position of the rib-shaped portion <NUM> to the leaf spring <NUM>. If it is assumed that these coupling positions are displaced in the vehicle longitudinal direction, the load acting on each of the two coupling positions (e.g., the load due to the own weight of the driving unit <NUM> and the load due to the operation of the driving unit <NUM>) cause a local moment to act on the side rails <NUM>, so that the stability of the states of coupling at the respective position may be degraded. On the other hand, since the coupling positions in the vehicle longitudinal direction of the present application example are the same, the moment as described above is less likely to be generated on the side rails <NUM>, so that the stability of the states of coupling at the respective position are enhanced.

<FIG>, and <FIG> are diagrams showing an integral bracket <NUM> applied to the electric vehicle <NUM> according to a modification. Like reference numbers in the modification designate the same or substantially the same as those of the above embodiment. The first coupler part <NUM> of the integral bracket <NUM> is provided with a second rib-shaped portion <NUM>. The second rib-shaped portion <NUM> is a portion formed to reinforce the first coupler part <NUM>, and is formed into a shape protruding outward or downward in the vehicle width direction.

The second rib-shaped portion <NUM> shown in <FIG> is provided with a pair of second planar parts <NUM>. The pair of second planar parts <NUM> are planar portions that are spaced apart in the vehicle longitudinal direction. Each second planar part <NUM> is integrally formed with the flat part <NUM> and is arranged along the direction perpendicular to the flat part <NUM>. Thereby, the first coupler part <NUM> is reinforced by the second planar parts <NUM>, and the stiffness of the integral bracket <NUM> is enhanced. The first wall part <NUM> and the second wall part <NUM> shown in <FIG> and <FIG> are arranged at a more inner part in the vehicle width direction than the first wall part <NUM> and the second wall part <NUM> in the above embodiment. Correspondingly, each of the pair of second planar parts <NUM> is oriented perpendicularly to the first wall part <NUM> and is integrally connected to the both sides of first wall part <NUM> (one on the vertical side positioning on the front side of the vehicle and the other on the vertical side positioning on the rear side of the vehicle).

Claim 1:
An electric vehicle (<NUM>) comprising a ladder frame (<NUM>) and a driving unit (<NUM>), the driving unit (<NUM>) comprising a motor (<NUM>) that generates driving force to be transmitted to an axle (<NUM>) of the electric vehicle (<NUM>) and a transmission mechanism (<NUM>) that shifts the driving force passed from the motor(<NUM>), characterized in that the electric vehicle (<NUM>) further comprising:
a motor housing (<NUM>) that accommodates the motor (<NUM>) of the driving unit (<NUM>);
a leaf spring (<NUM>) that suspends the axle (<NUM>) from the electric vehicle (<NUM>);
a first coupling part (<NUM>) that couples the ladder frame (<NUM>) to the motor housing (<NUM>); and
a second coupling part (<NUM>) that is integrated with the first coupling part (<NUM>) and that couples the ladder frame (<NUM>) to an end part of the leaf spring (<NUM>), wherein
the second coupling part (<NUM>) has a rib-shaped portion (<NUM>) that protrudes outward in the vehicle width direction and that is connected to the end part the leaf spring (<NUM>).