Power plant mount structure

Abstract

When a lower part of a power plant unit (PU) that generates drive force that is to make a vehicle travel is linked to a vehicle body by a torque rod (4) that is connected to a lower part of the vehicle body, an intermediate bracket (5) that is not as strong as a housing (3) of the power plant unit (PU) is interposed between and connected to the housing (3) of the power plant unit (PU) and the torque rod (4). As a result, even if the torque rod (4) interferes with a road surface, the intermediate bracket (5) is damaged before the housing (3) of the power plant unit (PU), making it possible to avoid damage to the housing (3) of the power plant unit (PU).

Description

Power plant mounting structure

[0001] The present invention relates to a power plant mounting structure.

[0002] In Patent Document 1, an engine and a transmission are arranged in series in the vehicle width direction to form a power plant unit, with the lower part of the engine housing connected to the vehicle body via a first torque rod and the lower part of the transmission housing connected to the vehicle body via a second torque rod. This power plant mounting structure is effective in reducing noise and vibration transmitted from the power plant unit to the vehicle body.

[0003] International Publication No. 2022 / 157833

[0004] However, in the example of Patent Document 1, if the second torque rod is disposed below the transmission housing, there is a risk of damage to the transmission housing if the second torque rod comes into contact with the road surface. In other words, a power plant mounting structure that can prevent damage to the power plant unit housing when mounting the power plant unit to the vehicle body using a torque rod is desired. An object of the present invention is to provide a power plant mounting structure that can prevent damage to the power plant unit housing.

[0005] One aspect of the present invention is characterized by comprising a power plant unit that generates driving force to run a vehicle, a torque rod connected to the lower part of the vehicle body to connect the lower part of the power plant unit to the vehicle body, and an intermediate bracket that is weaker in strength than the housing of the power plant unit and is interposed between the housing of the power plant unit and the torque rod to connect them both.

[0006] According to one aspect of the present invention, even if the torque rod interferes with the road surface, the intermediate bracket breaks before the power plant unit housing, thereby preventing damage to the power plant unit housing. The objects and advantages of the present invention are realized and attained by using the elements and combinations thereof set forth in the claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as defined by the claims.

[0007] 1 is a perspective view showing an embodiment of a main part of a power plant mounting structure; FIG. 2 is a perspective view of an intermediate bracket in the power plant mounting structure of FIG. 1; FIG. 3 is a left side view, partially in cross section, of a main part of the power plant mounting structure of FIG. 1; FIG. 4 is an explanatory diagram of the operation of the power plant mounting structure; FIG. 5 is an explanatory diagram of the operation of the power plant mounting structure; FIG. 6 is an explanatory diagram of the operation of the power plant mounting structure; FIG. 7 is an explanatory diagram of the operation of the power plant mounting structure; FIG. 8 is an explanatory diagram of the operation of the power plant mounting structure;

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. In the power plant mounting structure of the embodiment shown in FIG. 1 , an engine (not shown) and a motor 2 are arranged in series in the vehicle width direction to form a power plant unit PU. In this example, the engine is arranged on the right side of the vehicle, and the motor 2 is arranged on the left side of the vehicle. Unlike Patent Document 1, the power plant unit is formed by connecting the engine arranged on the left side of the vehicle to the transmission arranged on the right side of the vehicle. However, in this embodiment, both sides of the power plant unit PU in the vehicle width direction are connected (mounted) to the vehicle body via upper mount members (not shown) arranged on both outer sides in the vehicle width direction. In this embodiment, the lower part of the engine housing is connected (mounted) to the vehicle body via an engine-side torque rod (not shown), and the lower part of the housing 3 of the motor 2 is connected (mounted) to the vehicle body via a motor-side torque rod 4. The torque rods 4 are both arranged so that their longitudinal direction is the vehicle front-rear direction, and their rear ends are connected to the vehicle body and their front ends are connected to the power plant unit PU. The torque rod 4 that connects the housing 3 of the motor 2 to the vehicle body will be described in detail below.

[0009] FIG. 1 is a perspective view of the lower part of a housing 3 of a motor 2, which is connected to a vehicle body by a torque rod 4, as viewed from the left front of the vehicle. In this embodiment, the housing 3 of the motor 2 is connected to a suspension member (vehicle body) 1 together with not only the torque rod 4 but also an intermediate bracket 5. More specifically, the torque rod 4 is located on the suspension member 1 side, and the intermediate bracket 5 is located on the housing 3 side of the motor 2 side. More specifically, the intermediate bracket 5 is located above the vehicle with respect to the torque rod 4. As shown in FIG. 9 , the suspension member 1 is disposed below the vehicle rear portion of the power plant unit PU, and the torque rod 4 is connected to the front end of the suspension member 1. In the vehicle of this embodiment, lower suspension member sections 41 extend toward the front of the vehicle from both ends of the front end of the suspension member 1 in the vehicle width direction. The front ends of the lower suspension member sections 41 are connected to the lower ends of front bulkheads 43 that hang down from the front ends of left and right side frames 42. The front end of the lower suspension member 41 is curved slightly higher than the rear end, and a front cross member 6 is provided that extends in the vehicle width direction and connects the front ends of the left and right lower suspension members 41. The front cross member 6 is provided at a position on the front side of the power plant unit PU and at the same height as the lower end of the power plant unit PU.

[0010] In this embodiment, a boss portion 21 for attaching the intermediate bracket 5 protrudes outward in the vehicle width direction from a lower portion of the vehicle left side wall portion 3a of the housing 3 of the motor 2. In this embodiment, the intermediate bracket 5 is attached to the housing 3 of the motor 2 with two housing-side bolts (screw members) 7, and therefore two boss portions 21 for screwing the housing-side bolts 7 are protruded outward in the vehicle width direction from the vehicle left side wall portion 3a of the housing 3 of the motor 2. These boss portions 21 have a generally cylindrical shape with an axis extending from the upper front of the vehicle to the lower rear of the vehicle. A threaded hole (not shown) extending from the lower rear of the vehicle to the upper front of the vehicle is provided in the radial center of each boss portion 21, and the lower end surface of each boss portion 21 is provided in the same plane extending from the lower front of the vehicle to the upper rear of the vehicle, perpendicular to the axis of the threaded hole (= boss portion 21) (see FIG. 3a). In other words, the cylindrical bosses 21 onto which the two housing bolts 7 are threaded have their axes extending from the upper front to the lower rear of the vehicle, and the axes are spaced apart in the longitudinal direction of the vehicle. The strength of the intermediate bracket 5 is set to be smaller than the strength of the housing 3 of the motor 2.

[0011] Meanwhile, the vehicle front end of the torque rod 4 attached to the vehicle front end of the suspension member 1 is located below the boss portion 21, and this vehicle front end is provided with a bolt insertion portion 4a into which the shank of a vehicle body bolt (threaded member) 8 is inserted (see FIG. 3a). The bolt insertion portion 4a is a cylindrical portion whose axis extends vertically, and the shank of the vehicle body bolt 8 is inserted into the inner hole of this cylindrical portion from below the vehicle. Therefore, the axis of the vehicle body bolt 8 extends vertically, and the threaded portion (shank) is disposed upward of the vehicle. Note that while the shape of the torque rod 4 differs from that described in Patent Document 1, it is functionally similar, and vibration isolation and damping effects are obtained by interposing an elastic body 4d between a vehicle body support portion 4b attached to the suspension member (vehicle body) 1 and a power plant support portion 4c attached to the motor 2 via an intermediate bracket 5.

[0012] As shown in Fig. 2, the intermediate bracket 5 is configured by connecting a housing joint portion 5b, through which the housing bolt 7 is inserted, to the vehicle upper side of a rod mounting portion 5a, through which the vehicle body bolt 8 is screwed. The axis of the vehicle body bolt 8 extends vertically and the threaded portion (shank) faces upward on the vehicle, so the rod mounting portion 5a is configured as a stepped cylindrical portion whose axis extends vertically and whose diameter is larger on the vehicle lower side and smaller on the vehicle upper side. A threaded hole 5d, whose axis faces vertically upward, is formed in the radial center of this rod mounting portion 5a, extending partway up the height of the rod mounting portion 5a (cylindrical portion) (see Fig. 3a). In contrast, the housing joint portion 5b has a plate-shaped base plate portion 5c extending from the rod mounting portion 5a toward the upper side of the vehicle along the vehicle left side wall portion 3a of the housing 3 of the motor 2, and a flange portion 5e protruding in the vehicle longitudinal direction from the upper end of the base plate portion 5c, with an insertion hole 5f formed in each of the flange portions 5e for inserting the shank of the housing-side bolt 7. The upper side surfaces of the two flange portions 5e are formed as a series of flat surfaces extending from the lower front of the vehicle to the upper rear of the vehicle, similar to the lower end surfaces of the two boss portions 21, and the lower side surfaces of the flange portions 5e are formed as flat surfaces parallel to the flat surfaces, with the lower surfaces serving as bearing surfaces for the heads 7a of the housing-side bolts 7. The insertion hole 5f for inserting the shank of the housing-side bolt 7 is formed in an axial direction perpendicular to the upper and lower surfaces of the flange portions 5e and coincides with the axis of the screw holes of the two boss portions 21 when the intermediate bracket 5 is attached to the housing 3 of the motor 2. The attachment position PC of the intermediate bracket 5 to the housing 3 by the housing-side bolt 7 is defined as the center (middle) of the seating surface of the head 7a of the housing-side bolt 7 when the head 7a is seated on the flange portion 5e of the intermediate bracket 5. The attachment position PB of the intermediate bracket 5 to the torque rod 4 by the vehicle-side bolt 8 is defined as the center of the screw hole 5d on the underside of the rod attachment portion 5a when the intermediate bracket 5 is connected to the torque rod 4.

[0013] 3a is a partially sectional left side view showing a state in which the torque rod 4 is attached to the housing 3 via the intermediate bracket 5, and Fig. 3b is a schematic diagram showing two housing-side bolts 7 and their axes A7, an attachment position PC of the intermediate bracket 5 to the housing 3 and a line segment LS connecting them, a vehicle-body-side bolt 8 and its axis A8, an attachment position PB of the intermediate bracket 5 to the torque rod 4 and its plane (= the lower end surface of the rod attachment portion 5a) SP. In this embodiment, as shown in Fig. 3b, the attachment position PC of the intermediate bracket 5 by the two housing-side bolts 7 is offset in the fore-and-aft direction of the vehicle in a side view of the vehicle, and the attachment position PB of the intermediate bracket 5 by the vehicle-body-side bolt 8 is offset toward the rear of the vehicle in a side view of the vehicle with respect to an intermediate position CP between the attachment positions PC of the intermediate bracket 5 by the two housing-side bolts 7. Furthermore, a line segment LS connecting the attachment positions PC of the intermediate bracket 5 by the two housing-side bolts 7 extends obliquely upward from the front to the rear of the vehicle in a side view of the vehicle, and an extension of an axis A8 of the vehicle-body bolt 8 passes through the attachment position PC of the intermediate bracket 5 by the housing-side bolt 7 on the rear side of the vehicle. Figure 4 shows the two housing-side bolts 7 and the vehicle-body-side bolts 8 only by their axes A7 and A8, and illustrates a state in which the line segment LS connecting the attachment positions PC of the intermediate bracket 5 by the two housing-side bolts 7 (hereinafter referred to as the housing-side attachment position) is horizontal, and the attachment position PB of the intermediate bracket 5 by the vehicle-body-side bolts 8 (hereinafter referred to as the vehicle-body side attachment position) coincides with the midpoint CP of the connecting line segment LS. Now, consider a case in which the torque rod 4 interferes with the road surface and an external force F directed toward the rear of the vehicle acts at the attachment surface SP of the intermediate bracket 5 to the torque rod 4 (hereinafter referred to as the vehicle-body side attachment surface).

[0014] As described above, in this embodiment, the strength of the intermediate bracket 5 is set to be smaller than the strength of the housing 3 of the motor 2. Therefore, if the torque rod 4 interferes with the road surface and an external force F is applied to the torque rod 4, the intermediate bracket 5 will break before the housing 3 of the motor 2, thereby preventing damage to the housing 3 of the motor 2. However, in this embodiment, a design is made to ensure that the intermediate bracket 5 will break even if the same external force F is applied. In the example of FIG. 4 , when an external force F toward the rear of the vehicle acts on the vehicle body mounting surface SP, a moment M is generated in the counterclockwise direction as shown, with the arm being the distance between the vehicle body mounting position PB and the midpoint CP of the connecting line segment LS (= the distance from the vehicle body mounting position PB to the connecting line segment LS) and the center being the midpoint CP of the connecting line segment LS. Because the center position of this moment M is the midpoint CP of the connecting line segment LS, a force acts upward on the housing mounting position PC on the rear side of the vehicle, and a force acts downward on the housing mounting position PC on the front side of the vehicle. The force acting in the vehicle upward direction at the housing-side mounting position PC is a compressive force CF that presses the intermediate bracket 5 against the housing 3 of the motor 2, so the intermediate bracket 5 and the housing 3 of the motor 2 are not easily damaged. On the other hand, the force acting in the vehicle downward direction at the housing-side mounting position PC is a tensile force TF that pulls the housing-side bolts 7, so the intermediate bracket 5 is damaged, for example, by breaking the base of the flange portion 5e of the intermediate bracket 5. If the base of the flange portion 5e on the front side of the vehicle of the intermediate bracket 5 breaks, the base of the flange portion 5e on the rear side of the vehicle also tends to break.

[0015] In Figure 5, the connecting line segment LS in Figure 4 is maintained horizontal, and the vehicle-side mounting position PB is set rearward of the vehicle relative to the midpoint CP of the connecting line segment LS. With this setting, when an external force F toward the rear of the vehicle acts on the vehicle-side mounting surface SP, a moment M acts in the counterclockwise direction as shown, centered at the intersection X of the axis A8 of the vehicle-side bolt 8 and the connecting line segment LS. Because the connecting line segment LS is horizontal, the distance from the vehicle-side mounting position PB to the connecting line segment LS, which serves as the arm of the moment M when the external force F toward the rear of the vehicle acts on the vehicle-side mounting surface SP, is the same as in Figure 4, and the magnitude of the moment M centered at the intersection X of the axis A8 of the vehicle-side bolt 8 and the connecting line segment LS is also the same as in Figure 4. However, since the vehicle body mounting position PB is shifted toward the rear of the vehicle, the distance from the intersection X of the axis A8 of the vehicle body bolt 8 and the connecting line segment LS, i.e., the center of the moment M, to the housing-side mounting position PC on the rear side of the vehicle is smaller, and the distance from the center of the moment M to the housing-side mounting position PC on the front side of the vehicle is larger. Therefore, the compressive force CF acting on the housing-side mounting position PC on the rear side of the vehicle is smaller, and the tensile force TF acting on the housing-side mounting position PC on the front side of the vehicle is larger. Therefore, by setting the vehicle body mounting position PB, i.e., the mounting position of the intermediate bracket 5 by the vehicle body bolt 8, further rearward of the midpoint CP of the connecting line segment LS, i.e., the midpoint CP between the mounting positions of the intermediate bracket 5 by the two housing bolts 7, the intermediate bracket 5 is more susceptible to damage.

[0016] In Fig. 6, as in Fig. 4, the vehicle body mounting position PB coincides with the intermediate position CP of the connecting line segment LS, and as in the embodiment, the connecting line segment LS is set obliquely upward from the vehicle front to the vehicle rear. The distance between the vehicle body mounting position PB and the intermediate position CP of the connecting line segment LS (= the distance from the vehicle body mounting position PB to the connecting line segment LS) is the same as in Fig. 4. Therefore, as in Fig. 4, when an external force F toward the rear of the vehicle acts on the vehicle body mounting surface SP, a moment M acts in the counterclockwise direction in the figure about the intermediate position CP of the connecting line segment LS, and the magnitude of this moment M is the same as the moment M in Fig. 4. Therefore, both the compressive force CF acting on the housing-side mounting position PC on the vehicle rear side and the tensile force TF acting on the housing-side mounting position PC on the vehicle front side are equivalent to those in Fig. 4. However, if, from this state, the vehicle-side mounting position PB is set rearward of the intermediate position CP of the connecting line segment LS, as in the example of Figure 5, the distance from the vehicle-side mounting position PB to the connecting line segment LS becomes larger than the distance in Figure 5 because the connecting line segment LS points upward on the rear side of the vehicle, as shown in Figure 7. This distance is the arm of the moment M about the intersection X of the axis A8 of the vehicle-side bolt 8 and the connecting line segment LS, so even if the external force F is the same, the moment M becomes larger because the arm is longer. Therefore, the compressive force CF acting on the housing-side mounting position PC on the rear side of the vehicle in Figure 7 is larger than that in Figure 5, and the tensile force TF acting on the housing-side mounting position PC on the front side of the vehicle is also larger than that in Figure 5, making the intermediate bracket 5 more susceptible to damage. From the above, when the vehicle body side mounting position PB, i.e., the mounting position of the intermediate bracket 5 by the vehicle body side bolt 8, is set to be further rearward of the vehicle than the midpoint CP of the connecting line LS, i.e., the midpoint CP between the mounting positions of the intermediate bracket 5 by the two housing side bolts 7, by setting the connecting line LS diagonally upward from the front side of the vehicle to the rear side of the vehicle, the intermediate bracket 5 becomes even more susceptible to damage.

[0017] In Figure 6, the distance between the vehicle-body mounting position PB and the midpoint CP of the connecting line segment LS is the same as in Figure 4. However, if the height of the housing-side mounting position PC on the front side of the vehicle were the same as in Figure 4, simply setting the connecting line segment LS diagonally upward from the front side of the vehicle toward the rear side of the vehicle would make the distance between the vehicle-body mounting position PB and the midpoint CP of the connecting line segment LS greater than in Figure 4. If, under this assumption, the vehicle-body mounting position PB is set further rearward of the midpoint CP of the connecting line segment LS, the distance from the vehicle-body mounting position PB to the connecting line segment LS, which forms the arm of the moment M, would be even greater than in Figure 7. Therefore, the moment M about the intersection X of the axis A8 of the vehicle-body bolt 8 and the connecting line segment LS would also be greater. Therefore, simply setting the connecting line segment LS diagonally upward toward the rear of the vehicle would more reliably damage the intermediate bracket 5. Furthermore, in this embodiment, due to the configuration of the power plant unit PU, it is necessary to insert the housing-side bolt 7 into the flange portion 5e of the intermediate bracket 5 from the vehicle underside and screw it into the boss portion 21 of the housing 3. Furthermore, it is necessary to insert the vehicle-side bolt 8 into the rod mounting portion 5a of this intermediate bracket 5 from the vehicle underside of the bolt insertion portion 4a of the torque rod 4 and screw it into the rod mounting portion 5a. Therefore, it is also necessary to orient the connecting line LS, i.e., the bearing surface of the head portion 7a of the housing-side bolt 7 on the flange portion 5e, obliquely upward and facing the rear of the vehicle, so that the housing-side bolt 7 cannot be inserted into the intermediate bracket 5.

[0018] In Figure 8, the vehicle-side mounting position PB is set further rearward than in the state shown in Figure 7, so that the axis A8 (or its extension) of the vehicle-side bolt 8 passes through the housing-side mounting position PC at the rear of the vehicle, as in the embodiment. This maximizes the arm length of the moment M about the intersection X of the axis A8 of the vehicle-side bolt 8 and the connecting line LS, thereby further increasing the magnitude of the moment itself. At the same time, the distance from the center of this moment M to the housing-side mounting position PC at the front of the vehicle is also maximized, maximizing the tensile force TF acting on the housing-side mounting position PC at the front of the vehicle, thereby more reliably damaging the intermediate bracket 5. Furthermore, by making the intermediate bracket 5 more susceptible to damage even when the external force F acting due to interference between the torque rod 4 and the road surface is the same, the strength of the intermediate bracket 5 does not need to be significantly smaller than the strength of the housing 3 of the motor 2. Therefore, as long as the torque rod 4 does not interfere with the road surface, the intermediate bracket 5 is prevented from being easily damaged, and it is possible to ensure the rigidity of the connection (mount) of the power plant unit PU by the torque rod 4 and the intermediate bracket 5.

[0019] 9 is a left side view of a vehicle showing a schematic configuration of a front portion of the vehicle including the power plant mount structure of FIG. 1. As described above, in this embodiment, a front cross member 6 extending in the vehicle width direction is provided at a position on the front side of the power plant unit PU and at the height of the lower end of the power plant unit PU. In this embodiment, when the torque rod 4 interferes with the road surface, damage to only the intermediate bracket 5 is desired. Therefore, it is desirable that the lowest position of the intermediate bracket 5, which is interposed between the housing 3 of the motor 2 and the torque rod 4 on the vehicle upper side of the torque rod 4, be located higher in the height direction than the lowest position of the front cross member 6. If the intermediate bracket 5 were located lower than the lowest position of the front cross member 6, the intermediate bracket 5 may interfere with the road surface. In such a case, the above-described damage mechanism of the intermediate bracket 5 will not work, and the housing 3 of the motor 2 may be damaged. Furthermore, in the damage mechanism of this intermediate bracket 5, it is sufficient that a tensile force TF acts on the attachment position of the intermediate bracket 5 by the housing side bolt 7 (housing side attachment position PC), and therefore the housing side attachment position PC of the housing side bolt 7 on which this tensile force TF acts, specifically the housing side attachment position PC of the housing side bolt 7 on the front side of the vehicle, needs to be located higher in height than the lowest position of the front cross member 6.

[0020] 10 is a side view of the vehicle, illustrating the center of rotation RC of the power plant unit PU formed by the upper mount members described above and the power plant mount structure of FIG. 1 . The center of rotation RC of the power plant unit PU corresponds to the height of a line segment LS connecting the vehicle body connection positions of both sides of the power plant unit PU in the vehicle width direction via the two upper mount members. When the torque rod 4 interferes with the road surface while the vehicle is traveling forward, and an external force F acts on the torque rod 4 in the rearward direction of the vehicle, a moment M in the counterclockwise direction in FIG. 10 is generated near the housing-side mounting position PC of the intermediate bracket 5. In response, an inertial force FF acts on the power plant unit PU in the forward direction of the vehicle. Because the position at which power plant unit PU is connected (mounted) to the vehicle body by the upper mount member is higher than the center of gravity of power plant unit PU, when an inertial force FF toward the front of the vehicle acts on the center of gravity of power plant unit PU, a moment RF (hereinafter also referred to as an inertia-force-induced moment) is generated in power plant unit PU in the clockwise direction in Figure 10 with respect to the center of rotation RC of the upper mount member. Now, consider a circle that is centered on the center of rotation RC of power plant unit PU by the upper mount member and passes through the midpoint CP between the two housing-side mounting positions PC (the midpoint CP of the connecting line segment LS), and consider the force TF that acts in the tangent direction of the circle at the midpoint CP between the two housing-side mounting positions PC due to the inertia-force-induced moment RF. 11 illustrates the inertia-force-induced moment RF generated in the power plant unit PU and the tangential force TF acting at an intermediate position CP between the two housing-side mounting positions PC, and also compares the line segment LS connecting the two housing-side mounting positions PB on the intermediate bracket 5 (the line segment LS is highlighted). Specifically, Fig. 11a illustrates a state in which the angle θP formed by the line segment LS connecting the two housing-side mounting positions PC with the horizontal plane is larger than the angle θT formed by the tangent (direction) of the circle of the inertia-force-induced moment RF at the intermediate position CP between the two housing-side mounting positions PC with the horizontal plane, and Fig. 11b illustrates a state in which the angle θP is smaller than the angle θT (see Fig. 12).

[0021] 12, the tangential force TF due to the inertia-force-induced moment RF is broken down into a component force PF along the direction of a line segment LS connecting the two housing-side mounting positions PC and a component force VF perpendicular to the component force PF. In the following, the tangential force acting on the intermediate position CP between the two housing-side mounting positions PC due to the inertia-force-induced moment RF of the power plant unit PU is defined as a tangential force FT, the line segment LS connecting the two housing-side mounting positions PC is defined as a housing-side mounting surface BP, the angle that this housing-side mounting surface BP makes with the horizontal plane is defined as a mounting surface angle θP, and the angle that the tangent to the circle of the inertia-force-induced moment RF at the intermediate position CP between the two housing-side mounting positions PC is defined as a tangential force angle θT. 12a, when the mounting surface angle θP is greater than the tangential force angle θT, the component forces PF and VF of the tangential force FT in the direction of the housing-side mounting surface BP and in the direction perpendicular thereto both act in directions that move the vehicle-side mounting position PB and the housing-side mounting position PC of the intermediate bracket 5 apart. On the other hand, as shown in Fig. 12b, when the mounting surface angle θP is smaller than the tangential force angle θT, the component force PF of the tangential force FT in the direction of the housing-side mounting surface BP acts in a direction that moves the vehicle-side mounting position PB and the housing-side mounting position PC of the intermediate bracket 5 apart, but the component force VF in the direction perpendicular thereto acts in a direction that moves the vehicle-side mounting position PB and the housing-side mounting position PC of the intermediate bracket 5 closer together. The breakage mechanism of the intermediate bracket 5 described above is due to the tensile force TF that pulls the housing-side bolt 7, and therefore, any component force of the tangential force FT acting in a direction that moves the intermediate bracket 5 away from the vehicle-side mounting position PB and the housing-side mounting position PC contributes to breakage of the intermediate bracket 5. Therefore, by setting the mounting surface angle θP larger than the tangential force angle θT, the intermediate bracket 5 is more likely to be broken when an external force F toward the rear of the vehicle acts on the torque rod 4.

[0022] Although the power plant mounting structure according to the embodiment has been described above, the present invention is not limited to the configuration described in the above embodiment and various modifications are possible within the scope of the present invention. For example, the above embodiment describes a mounting structure that connects the housing 3 of the motor 2 constituting the power plant unit PU to the suspension member (vehicle body) 1. However, the present invention can be applied to the lower part of the housing of any power plant unit component as long as the lower part of the power plant unit PU is connected to the vehicle body via a torque rod 4. For example, in the example of Patent Document 1, the present invention can be applied to the mounting structure that connects the lower part of the transmission housing to the vehicle body. Furthermore, in the above embodiment, the power plant mounting structure as a whole has a structure similar to the pendulum mounting system described in Patent Document 1, but the present invention can also be applied to other power plant mounting structures.

[0023] As described above, in this embodiment, when the lower part of the power plant unit PU, which generates the driving force for running the vehicle, is connected to the vehicle body by the torque rod 4 connected to the lower part of the vehicle body, an intermediate bracket 5 having a strength less than that of the housing 3 of the power plant unit PU is interposed between the housing 3 of the power plant unit PU and the torque rod 4 to connect them together. As a result, even if the torque rod 4 comes into contact with the road surface, the intermediate bracket 5 breaks before the housing 3 of the power plant unit PU does, thereby preventing damage to the housing 3 of the power plant unit PU. Furthermore, by interposing the intermediate bracket 5 between the housing 3 of the power plant unit PU and the torque rod 4 on the vehicle upper side of the torque rod 4, it is possible to limit damage to only the intermediate bracket 5 when the torque rod 4 comes into contact with the road surface.

[0024] Furthermore, the intermediate bracket 5 is connected to the housing 3 with two housing-side bolts 7 and to the torque rod 4 with one vehicle-body bolt 8, and the attachment positions of the intermediate bracket 5 by the two housing-side bolts 7 are offset in the fore-and-aft direction of the vehicle in a side view of the vehicle, and the attachment position of the intermediate bracket 5 by the vehicle-body bolt 8 is offset toward the rear of the vehicle in a side view of the vehicle from the midpoint CP between the attachment positions PC of the intermediate bracket 5 by the two housing-side bolts 7. This increases the tensile force TF acting on the housing-side bolt 7 on the front side of the vehicle when the torque rod 4 interferes with the road surface while the vehicle is traveling forward, thereby making the intermediate bracket 5 more susceptible to damage. Furthermore, by setting the line segment LS connecting the attachment positions of the intermediate bracket 5 by the two housing-side bolts 7 upward from the front side of the vehicle toward the rear side of the vehicle when the torque rod 4 interferes with the road surface while the vehicle is traveling forward, this further increases the tensile force TF acting on the housing-side bolt 7 on the front side of the vehicle, making the intermediate bracket 5 more susceptible to damage. Furthermore, by setting the axis A8 of the vehicle body side bolt 8 to pass through the attachment position of the intermediate bracket 5 by the housing side bolt 7 on the rear side of the vehicle, when the torque rod 4 interferes with the road surface while the vehicle is traveling forward, the tensile force TF acting on the housing side bolt 7 on the front side of the vehicle can be made even larger, and as a result, the intermediate bracket 5 can be made even more susceptible to damage.

[0025] Furthermore, if a front cross member 6 extending in the vehicle width direction is provided at a position on the front side of the power plant unit PU and at the height of the lower end of the power plant unit PU, by setting the lowest position of the intermediate bracket 5 higher in the height direction than the lowest position of the front cross member 6, it is possible to limit damage to only the intermediate bracket 5 when the torque rod 4 interferes with the road surface while the vehicle is traveling forward. Furthermore, if the housing-side bolts 7 on the front side of the vehicle are positioned lower than the housing-side bolts 7 on the rear side of the vehicle, by setting the attachment position of the intermediate bracket 5 with the housing-side bolts 7 higher in the height direction than the lowest position of the front cross member 6, it is possible to limit damage to only the intermediate bracket 5 when the torque rod 4 interferes with the road surface while the vehicle is traveling forward.

[0026] Furthermore, when both vehicle width direction side ends of the power plant unit PU are connected to the vehicle body via upper mount members, the angle that a line segment LS that connects the mounting positions of the intermediate bracket 5 by the two housing-side bolts 7 makes with the horizontal plane is set larger than the angle that a tangent to a circle (inertia force-induced moment RF) that is centered on the center of rotation RC of the power plant unit PU by the upper mount members and passes through the midpoint CP of the mounting positions PC of the intermediate bracket 5 by the two housing-side bolts 7 makes with the horizontal plane at the midpoint CP. This makes it possible to convert the tangential force due to the inertia force-induced moment RF into a component force that efficiently separates the housing-side mounting position PC and the vehicle-body-side mounting position PB of the intermediate bracket 5, making it even more likely to break the intermediate bracket 5 when the torque rod 4 interferes with the road surface while the vehicle is traveling forward. In addition, by setting the mounting position of the intermediate bracket 5 using the two housing side bolts 7 to the rear of the line LS connecting the vehicle body connection positions on both sides of the power plant unit PU in the vehicle width direction using the upper mounting member, the length of the torque rod 4 in the vehicle fore-and-aft direction can be reduced.

[0027] 1...Suspension member (vehicle body), 2...Motor, 3...Housing, 4...Torque rod, 5...Intermediate bracket, 6...Front cross member, 7...Housing-side bolt (screw member), 8...Vehicle-side bolt (screw member), PU...Power plant unit, LS...Line segment

Claims

1. A power plant mounting structure comprising: a power plant unit that generates driving force to run a vehicle; a torque rod connected to the lower part of a vehicle body to connect the lower part of the power plant unit to the vehicle body; and an intermediate bracket that has a strength less than that of the housing of the power plant unit and is interposed between the housing of the power plant unit and the torque rod to connect them both.

2. The power plant mounting structure according to claim 1, wherein the intermediate bracket is interposed between the power plant unit housing and the torque rod on the vehicle upper side of the torque rod.

3. The power plant mounting structure described in claim 1, characterized in that the intermediate bracket is connected to the housing with two housing-side screw members and to the torque rod with one vehicle-side screw member, the mounting positions of the intermediate bracket by the two housing-side screw members are offset in the fore-and-aft direction of the vehicle in a side view of the vehicle, and the mounting position of the intermediate bracket by the vehicle-side screw member is offset toward the rear of the vehicle in a side view of the vehicle from the midpoint between the mounting positions of the intermediate bracket by the two housing-side screw members.

4. A power plant mounting structure as described in claim 3, characterized in that the line connecting the mounting positions of the intermediate bracket by the two housing side screw members points upward from the front of the vehicle to the rear of the vehicle when viewed from the side of the vehicle.

5. A power plant mounting structure according to claim 4, wherein the axis of the vehicle body side screw member passes through the position at the rear of the vehicle where the intermediate bracket is attached by the housing side screw member.

6. A power plant mounting structure as described in claim 2, characterized in that a front cross member extending in the vehicle width direction is provided at a position on the front side of the power plant unit and at the height of the lower end of the power plant unit, and the lowest position of the intermediate bracket is located higher in the height direction than the lowest position of the front cross member.

7. A power plant mounting structure as described in claim 3, characterized in that a front cross member extending in the vehicle width direction is provided at a position on the front side of the power plant unit and at the height position of the lower end of the power plant unit, and the attachment position of the intermediate bracket using the housing side screw member is located higher in the height direction than the lowest position of the front cross member.

8. A power plant mounting structure as described in claim 4, characterized in that both sides of the power plant unit in the vehicle width direction are connected to the vehicle body via upper mounting members, and the angle formed by the line segment connecting the mounting positions of the intermediate bracket by the two housing side screw members and the horizontal plane is larger than the angle formed by the tangent at the midpoint of a circle whose center is the center of rotation of the power plant unit by the upper mounting members and passes through the midpoint of the mounting positions of the intermediate bracket by the two housing side screw members and the horizontal plane.

9. A power plant mounting structure as described in claim 8, characterized in that the mounting position of the intermediate bracket using the two housing side screw members is located rearward of the line connecting the vehicle body connection positions of both sides of the power plant unit in the vehicle width direction using the upper mounting member.

Images