Patent Description:
A Patent Literature <NUM> listed below discloses an installation structure for a high-voltage electrical device on a vehicle. A high-voltage voltage electrical device is a device that handles a high voltage (60V or higher), and a special electrical system with a dedicated grounding wire, rather than body grounding, is used for the high-voltage electrical device. In the installation structure, a bracket integrally and horizontally protruding from a side wall of a housing of the high-voltage electrical device is fixed to a vehicle body by a bolt. In the event of a vehicle frontal collision, a vulnerable portion in the bracket is broken, and thereby a main unit of the high-voltage electrical device (electric components within its housing) is protected without being exposed.

In the installation structure disclosed in the Patent Literature <NUM>, an impact load at the time of the frontal collision effectively acts to break the bracket, because the high-voltage electrical device and the fixing position to the vehicle are located at the same height level. However, if the height level of the high-voltage electrical device and the height level of the fixing position to the vehicle are different, a bending moment is generated in the bracket, and a tensile load acts on the housing of the high-voltage electrical device due to the moment. As a result, a main body of the housing may be torn off, and thereby the electrical components within the housing may be exposed. In other words, in such a case, there is a possibility that the high-voltage electrical device will not be reliably protected.

In an installation structure for a high-voltage electrical device installed on a front section of a vehicle according to an aspect of the present invention, the high-voltage electrical device is attached to a cross member of a vehicle body by an L-shaped front bracket. The cross member extends in a lateral direction of the vehicle in front of the high-voltage electrical device. A boss, at the center of which a bolt hole is formed, protrudes forward from a front panel of a housing of the high-voltage electrical device. A lower vertical portion of the front bracket is fastened to the boss by a bolt and its upper horizontal portion is fixed to the cross member. A vulnerable portion is formed at a root of the boss.

According to the aspect, the high-voltage electrical device installed on the front section of the vehicle can be protected reliably in the event of a vehicle frontal collision.

Hereinafter, an installation structure according to an embodiment will be described with reference to <FIG>. A high-voltage electrical device <NUM> is installed at a front section of a vehicle by this installation structure. Note that a forward direction of the vehicle is indicated by an arrow FR in <FIG> and <FIG>.

As shown in <FIG> and <FIG>, the high-voltage electrical device <NUM> according to the installation structure in the present embodiment is installed in a motor room at the front section of the vehicle. A high voltage battery (not shown) is installed on the vehicle, and the vehicle is a battery electric vehicle (BEV) that runs on electricity stored in the high voltage battery. The high-voltage electrical device <NUM> is an OBC (On-Board Charger) unit that charges the high voltage battery. The high-voltage electrical device <NUM> is one of high-voltage electrical devices that handle high voltages (60V or higher). Hereinafter, the high-voltage electrical device <NUM> according to the installation structure in the present embodiment is referred to the OBC unit <NUM>.

The OBC unit <NUM> includes an OBC 1a, a DCDC converter 1b, and a junction box 1c. Each of these is also a high-voltage electrical device. The OBC 1a has a housing <NUM> (see <FIG>), and the DCDC converter 1b and the junction box 1c are fixed to the housing <NUM>. The DCDC converter 1b is fixed to a lower portion of the housing <NUM>, and the junction box 1c is fixed to an upper portion of the housing <NUM>.

An inverter <NUM> and a high voltage electric motor <NUM> are installed beneath the OBC unit <NUM>. Each of these is also a high-voltage electrical device. The inverter <NUM> and the high voltage electric motor <NUM> are integrated with being housed in a single housing. The inverter <NUM> and the high voltage electric motor <NUM> are attached to a subframe, and the subframe is attached to side members (not shown) of the vehicle body.

The OBC unit <NUM> is attached to cross members <NUM> and <NUM> that construct a vehicle body such that it is suspended by L-shaped brackets <NUM> (2f and 2r). More specifically, the housing <NUM> of the OBC 1a is attached to the vehicle body by the L-shaped brackets <NUM> (2f and 2r), and thereby the DCDC converter 1b and the junction box 1c are also attached to the car body via the OBC 1a.

In front of the OBC unit <NUM>, the cross member <NUM> extends in a lateral direction of the vehicle. The cross member <NUM> is specifically a radiator core upper support that supports an upper portion of a radiator core <NUM>. On the other hand, the cross member <NUM> extends in the lateral direction behind the OBC unit <NUM>. The OBC unit <NUM>, i.e., the housing <NUM> of the OBC 1a, is installed such that it is suspended by a pair of the front brackets 2f and a pair of the rear brackets 2r from the cross members <NUM> and <NUM>.

As shown in <FIG>, two pairs of cylindrical bosses <NUM> are protruded forward from a front plate <NUM> of the housing <NUM>. A bolt hole 102a (see <FIG>) is formed in the center of each of the bosses <NUM>. In addition, a reinforcing rib 102b is also formed between each pair of the bosses <NUM>. The housing <NUM> is made of aluminum, and its rear plate <NUM>, its side plates and its bottom plate <NUM> and so on are also integrally formed in addition to the front plate <NUM> and the bosses <NUM>. The one pair of the bosses <NUM> is provided on a right portion of the housing <NUM> so as to be lined up vertically. The other pair of the bosses <NUM> is provided on a left portion of the housing <NUM> so as to be lined up vertically.

Note that a lid of the housing <NUM> is not shown in <FIG>, but the lid is attached by using screw holes <NUM>. A pair of brackets <NUM> protrudes forward from the top edge of the front plate <NUM>, and another pair of brackets <NUM> protrudes rearward from the top edge of the rear plate <NUM>. The above-mentioned junction box 1c is secured to these brackets <NUM>. Plural ribs <NUM> are also formed on the front face of the front plate <NUM> at intervals. The ribs <NUM> and the brackets <NUM> are also integrally formed with the housing <NUM>.

A lower vertical portion of the front bracket 2f is fastened to each pair of the above-mentioned bosses <NUM> by bolts <NUM>. Both side edges of the front bracket 2f are flanged to improve rigidity and strength. The front bracket 2f is an angle member made of steel. A pair of bolt insertion holes <NUM> for inserting the bolts <NUM> are formed on the lower vertical portion of the front bracket 2f. The bolts <NUM> are fastened to the above-mentioned bolt holes 102a. On the other hand, bolt insertion holes <NUM> are also formed on an upper horizontal portion of the front bracket 2f. The upper horizontal portion of the front bracket 2f is secured to the cross member <NUM> by the bolt insertion holes <NUM>.

A vulnerable portion is formed at a root of the lower boss <NUM> of the two bosses <NUM> in each pair. The vulnerable portion breaks when the front bracket 2f moves backward relative to the housing <NUM> during a frontal collision of the vehicle, and thereby a main body of the housing <NUM> can be prevented from being damaged. This prevents the electrical components within the housing <NUM> from being exposed and reliably protects the OBC 1a, i.e., the OBC unit <NUM>. The vulnerable portion in the present embodiment is specifically constructed by following structures [<NUM>] and [<NUM>].

In the present embodiment, a front-to-back width of the upper portion of the pedestal <NUM> is made larger than a front-to-back width of the lower portion of the pedestal <NUM> as shown in <FIG>. That is, the surface of the pedestal <NUM> is sloped. Therefore, when a tensile force acts on the lower boss <NUM> to pull out the bolt <NUM>, the lower portion of the pedestal <NUM> is more able to resist the tensile force than the upper portion of the pedestal <NUM>. The tensile force acts during the frontal collision of the vehicle, and this will be explained later. Note that, also with respect to the rib <NUM>, a front-to-rear width of its upper portion is also made larger than a front-to-rear width of its lower portion.

Since the thickness t1 of the boss <NUM> is smaller than the thickness t2 of the pedestal <NUM>, the vulnerable portion at the root of the boss <NUM> breaks when the above-mentioned tensile force acts on the boss <NUM> and thereby the main body of the housing <NUM>, including the front plate <NUM> on which the pedestal <NUM> is formed, can be prevented from being damaged. This prevents the interior of the housing <NUM> from being exposed.

[<NUM>] Furthermore, a rising curvature radius R1 of the root of the boss <NUM> as the vulnerable portion from the pedestal <NUM> is made smaller than a rising curvature radius R2 of the pedestal <NUM> from the front plate <NUM> as shown in <FIG>. Therefore, more stress is concentrated on the vulnerable portion at the root of the boss <NUM> when the above-mentioned tensile force acts on the boss <NUM>. Thus, the vulnerable portion at the root of the boss <NUM> is more prone to break.

Note that, in the present embodiment, the installation structure on the front side of the above-mentioned OBC unit <NUM> is symmetrically constructed also on the rear side of the OBC unit <NUM>. That is, two pairs of cylindrical bosses <NUM> protrude rearward integrally from the rear plate <NUM> of the housing <NUM>. The one pair of the bosses <NUM> is provided on the right portion of the housing <NUM> so as to be lined up vertically, and the other pair of the bosses <NUM> is provided on the left portion of the housing <NUM> so as to be lined up vertically. Then, a lower vertical portion of a rear bracket 2r is fastened to each pair of the bosses <NUM> by bolts, and an upper horizontal portion of the rear bracket 2r is fixed to the cross member <NUM>. The lower boss <NUM> in each pair of the bosses <NUM> has the above-mentioned vulnerable portion.

The action of the tensile force on the lower boss <NUM> during a frontal collision of the vehicle will be described with reference to <FIG>. As mentioned above, the OBC unit <NUM> is attached to the cross members <NUM> and <NUM> so as to be suspended by the L-shaped brackets <NUM> (2f and 2r). During the frontal collision of the vehicle, the front end of the vehicle collapses and moves rearward relative to the vehicle body. In association with this, the cross member, which is the radiator core upper support, is pushed toward the OBC unit <NUM>.

At that moment, as indicated by an arrow F in <FIG>, an impact load F moves the upper horizontal portion of the front bracket 2f relatively rearward via the cross member <NUM>. As a result, a compressive force acts on the upper boss <NUM> and, as indicated by an arrow Ft in <FIG>, a tensile force Ft acts on the lower boss <NUM> to pull out the bolt <NUM> by the principle of leverage. The tensile force Ft acting on the lower boss <NUM> causes the boss <NUM> to break at the vulnerable portion, i.e., at its root. Due to the break of the boss <NUM>, the main body of the housing <NUM>, i.e., the front plate <NUM>, can be prevented from being damaged. As a result, the electrical components within the housing <NUM> are not exposed.

Here in the present embodiment, furthermore, as shown in <FIG>, the thickness of the bottom plate <NUM> on the opposite side to the boss <NUM> with respect to the front plate <NUM> is locally made large to form a thick portion 106a. That is, the thickness of the thick portion 106a is larger than the thickness of the other portions of the bottom plate <NUM> than the thick portion 106a. Not only is the front plate <NUM> reinforced by the pedestal <NUM>, but the bottom plate <NUM> is also locally reinforced by the thick portion 106a, and thereby the main body of the housing <NUM> can more effectively resist the above-mentioned tensile force Ft. As a result, the damage to the main body of the housing <NUM>, for example, separation of the front plate <NUM> from the bottom plate <NUM>, can be prevented.

As explained above, the above-described installation structure is symmetrically constructed on the rear side of the OBC unit <NUM>. If the impact load F is large and the OBC unit <NUM> is moved rearward relative to the vehicle body from the state shown in <FIG>, the tensile force acts on the lower boss <NUM> on the rear side of the housing <NUM>. Therefore, the vulnerable portion of the lower boss <NUM> breaks and the main body of the housing <NUM>, i.e., the rear plate <NUM>, can be prevented from being damaged. As a result, the electrical components within the housing <NUM> are not exposed.

As explained above, the installation structure of the present embodiment has the boss <NUM> protruding forward from the front plate <NUM> of the housing <NUM> of the high-voltage electrical device <NUM>, the cross member <NUM> extending in the lateral direction in front of the high-voltage electrical device <NUM>, and the L-shaped front bracket 2f. The lower vertical portion of the front bracket 2f is fastened to the bolt hole 102a of the boss <NUM> by the bolt <NUM>, and its upper horizontal portion is fixed to the cross member <NUM>. And, the vulnerable portion is formed at the root of the (lower) boss <NUM>. Therefore, the vulnerable portion formed at the root of the boss <NUM> breaks in the event of a vehicle frontal collision, and thereby the main body of the housing <NUM> can be prevented from being damaged and the high-voltage strong electrical device <NUM> can be protected reliably.

With respect to the above-mentioned vulnerable portion, the boss <NUM> protrudes forward from the pedestal <NUM> formed on the front plate <NUM>. In addition, the thickness t1 of the root of the boss <NUM> in the direction perpendicular to the axial line O of the bolt hole 102a is made smaller than the thickness t2 of the pedestal <NUM> in that direction. Therefore, the boss <NUM> can be securely broken at the vulnerable portion at the root of the boss <NUM>.

In addition, with respect to the above-mentioned vulnerable portion, the rising curvature radius R1 of the root of the boss <NUM> from the pedestal <NUM> is made smaller than the curvature radius R2 of the pedestal <NUM> from the front plate <NUM>. Thus, the boss <NUM> can be more reliably broken at the vulnerable portion at the root of the boss <NUM>.

Furthermore, the thickness of the bottom plate <NUM> on the opposite side to the boss <NUM> with respect to the front plate <NUM> is made locally large to form the thick portion 106a. Thus, the housing <NUM> can be more reliably prevented from being damaged.

Claim 1:
An installation structure of a high-voltage electrical device (<NUM>, 1a) installed on a front section of a vehicle, the structure comprising:
the high-voltage electrical device (<NUM>, 1a);
a boss (<NUM>) that protrudes forward from a front panel (<NUM>) of a housing (<NUM>) of the high-voltage electrical device (<NUM>, 1a), a bolt hole (102a) being formed at the center of the boss (<NUM>);
a cross member (<NUM>) that extends in a lateral direction of the vehicle in front of the high-voltage electrical device (<NUM>, 1a) to construct a vehicle body of the vehicle; and
an L-shaped front bracket (2f) whose lower vertical portion is fastened to the boss (<NUM>) by a bolt (<NUM>) and whose upper horizontal portion is fixed to the cross member (<NUM>),
wherein a vulnerable portion is formed at a root of the boss (<NUM>).