Vehicle structure

Abstract

[Problem] To provide a novel vehicle structure including an under cover. [Solution] The present invention comprises: a battery 20 disposed under the floor of a vehicle; an electric power train 40 that is for driving the rear wheels of the vehicle and is provided under the floor and behind the battery; and an under cover 60 that is provided below the electric power train. In the electric power train, a motor 42 is arranged on the rear side and a differential 41 connected via the motor and a gear train is arranged on the front side. The under cover has an intake port 63 that is provided at a position in front of the motor and is capable of taking in cooling air.

Description

Vehicle structure

[0001] The present invention relates to a vehicle structure.

[0002] Important components related to the running of a vehicle may be located under the vehicle. For example, Patent Document 1 discloses a technology that includes a battery located under the floor of the vehicle and an electric powertrain that is provided under the floor and behind the battery and that drives the rear wheels of the vehicle.

[0003] JP 2023-122988 A

[0004] In some automobiles, an undercover is provided under the vehicle to reduce air resistance. In this regard, Patent Document 1 does not disclose an undercover, and there is room for further consideration when providing an undercover below an electric powertrain that drives the rear wheels.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a novel vehicle structure including an undercover.

[0006] One aspect of the present invention includes a battery located under the floor of a vehicle, an electric powertrain located under the floor and behind the battery and driving the rear wheels of the vehicle, and an undercover located below the electric powertrain. The electric powertrain has a motor at the rear and a differential connected to the motor via a gear train at the front. The undercover is located in front of the motor and has a cooling air intake for taking in cooling air.

[0007] According to the above vehicle structure, a novel vehicle structure including an undercover can be provided.

[0008] Fig. 1 is a schematic side view showing a vehicle structure according to an embodiment. Fig. 2 is a schematic view showing the interior of an electric powertrain that constitutes the vehicle structure. Fig. 3 is a schematic perspective view showing a suspension member, a motor, a differential, etc. that constitute the vehicle structure of Fig. 1. Fig. 4 is a plan view showing a suspension member, a motor, a differential, etc. Fig. 5 is a schematic bottom view showing an undercover. Fig. 6 is a schematic perspective view showing a sound absorbing and insulating cover and a suspension member. Fig. 7 is a schematic perspective view showing an electric powertrain and a suspension member. Fig. 8 is a schematic view showing a motor, a gear train, and a differential.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted. In the drawings, the size and proportions of each component are exaggerated to facilitate understanding of the embodiments, and may differ from the actual size and proportions.

[0010] In each figure, arrows (coordinate system) represented by X, Y, and Z are used to indicate the orientation of members constituting the vehicle structure according to the embodiment. X indicates the front-rear direction, which is referred to as the front-rear direction X. Y indicates the vehicle width direction, which is referred to as the vehicle width direction Y. Z indicates the vehicle height direction, which is referred to as the height direction Z.

[0011] FIG. 1 is a schematic side view showing a vehicle structure according to an embodiment. FIG. 2 is a schematic view showing the interior of an electric powertrain 40 that constitutes the vehicle structure. FIG. 3 is a schematic perspective view showing a suspension member 30 and the like that constitute the vehicle structure of FIG. 1. FIG. 4 is a plan view showing the suspension member 30, a motor 42, a differential 41, and the like. FIG. 5 is a schematic bottom view showing an undercover 60. FIG. 6 is a schematic perspective view showing a sound-absorbing and insulating cover 50 and the suspension member 30. FIG. 7 is a schematic perspective view showing the electric powertrain 40 and the suspension member 30. FIG. 8 is a schematic view showing the motor 42, the gear train, and the differential 41.

[0012] The vehicle structure according to this embodiment can be used in electric vehicles and hybrid cars. As shown in Figures 1, 2, 3, etc., the vehicle structure according to this embodiment includes a side sill 10, a battery 20, a suspension member 30, an electric powertrain 40, a sound absorbing and insulating cover 50, an undercover 60, a rear bumper 70, and an inter-pin bar 80. These will be described in detail below.

[0013] (Side Sill) The side sill 10 is configured to be located below the door, which is part of the vehicle. The side sill 10 is a vehicle frame member that extends in the longitudinal direction X of the vehicle and forms a closed cross section. The side sill 10 is disposed at the left and right ends in the vehicle width direction Y. The rear end of the side sill 10 can be joined to the front end of a rear side member 90 (see FIG. 1). The rear side member 90 is a frame member that extends in the longitudinal direction X of the vehicle and is provided below the floor panel.

[0014] (Battery) The battery 20 is located inward of the side sill 10 in the vehicle width direction Y and below the floor panel, in other words, under the vehicle floor. The battery 20 includes a positive electrode, a negative electrode, an electrolyte, a current collector, an exterior body, etc., and is configured to be capable of charging and discharging. The battery 20 is located below the floor panel (under the floor) of the electric vehicle, with its underside lower than the underside of the side sill 10. The battery 20 can be connected to the side sill 10 at both ends in the vehicle width direction Y by bolts or the like via parts such as side frames (not shown).

[0015] (Suspension Member) The suspension member 30 is provided below the floor panel and behind the battery 20, and supports the rear wheel suspension and the electric powertrain 40. The suspension member 30 is configured to support the motor 42 constituting the electric powertrain 40 at the rear side and to support the differential 41 at the front side. As shown in FIG. 3 , the suspension member 30 includes a pair of left and right side members 31, a front cross member 32, a rear cross member 33, an undercross member 34, and a connecting portion 35.

[0016] The pair of left and right side members 31 are skeletal components extending in the longitudinal direction X of the vehicle. The pair of left and right side members 31 are provided as a pair on the left and right in the vehicle width direction Y. An electric powertrain 40 is disposed between the pair of left and right side members 31. The pair of left and right side members 31 have connecting portions 35 at their front and rear ends. The suspension member 30 is attached to the rear side member 90 by four connecting portions 35.

[0017] The front cross member 32 is a framework member that extends in the vehicle width direction Y and spans between the pair of left and right side members 31 , and is provided in front of the pair of left and right side members 31 .

[0018] The rear cross member 33 is a frame member that extends in the vehicle width direction Y and spans between the pair of left and right side members 31, and is provided at the rear of the pair of left and right side members 31. The rear cross member 33 is disposed at approximately the same height as the front cross member 32 in the height direction Z, and the electric powertrain 40 is disposed between the rear cross member 33 and the front cross member 32.

[0019] The undercross member 34 is a framework member that extends in the vehicle width direction Y and spans between the pair of left and right side members 31, and is provided at the intermediate portion of the pair of left and right side members 31. Specifically, the undercross member 34 has a pair of left and right extending portions 36 that extend downward from the intermediate portions of the pair of left and right side members 31, and the undercross member 34 spans between the pair of left and right extending portions 36. The undercross member 34 is disposed between the front cross member 32 and the rear cross member 33 in a plan view. The undercross member 34 is provided lower relative to the front cross member 32 and the rear cross member 33, and the lowermost portion of the undercross member 34 is provided lower than the lowermost portions of the front cross member 32 and the rear cross member 33. The undercross member 34 is disposed below the motor 42 of the electric powertrain 40.

[0020] An inter-pin bar 80, which will be described later, is bridged between the two rearmost connecting portions 35 of the four connecting portions 35. The front connecting portion 35 is attached to the rear side member 90 with bolts or the like. The rear connecting portion 35, together with the inter-pin bar 80, is attached to the rear side member 90 with bolts or the like. By arranging the inter-pin bar 80 in this manner, the rigidity of the suspension member 30 is improved.

[0021] (Electric Powertrain) The electric powertrain 40 is provided behind the battery 20 and is configured to drive the rear wheels of the vehicle. The electric powertrain 40 converts DC power output from the battery 20 into AC power using an inverter N and supplies the AC power to the motor 42, thereby driving the motor 42. When the motor 42 rotates in response to the drive wheels, the inverter N converts regenerative AC power generated by the motor 42 into DC power and inputs it to the battery 20, thereby charging the battery 20.

[0022] The electric powertrain 40 has a housing C attached to the front cross member 32 and the rear cross member 33 of the suspension member 30, with two bushings or the like attached to each housing C so that the axes of the insulators extend in the front-to-rear direction. The motor 42 is located behind the differential 41 (see Figures 2 and 4).

[0023] The differential 41 is connected to the motor 42 via a gear train and has a ring gear 47 and a differential case 43 that is integral with the ring gear 47 and rotates integrally with the ring gear 47 (see FIG. 8 ). The differential 41 has a differential mechanism (not shown) that is provided inside the differential case 43 and is formed by a pinion shaft, pinion gears, and left and right side gears. The left and right side gears are connected to left and right drive shafts 48, 49.

[0024] The gear train is configured to reduce the speed of the rotation from the motor 42. The reduction mechanism includes an electric motor final reduction gear 46 and an electric motor gear train 45. The electric motor final reduction gear 46 meshes with a ring gear 47 of the differential 41. The electric motor gear train 45 is a gear train having two meshed gears 45a and 45b. The gear 45a is connected to the electric motor final reduction gear 46. The gear 45b is connected to the electric motor 42 via a gear 45c and a pinion 42b connected to the motor output shaft 42a. The axial position of the electric motor gear train 45 is within the axial range from the end face of the differential case 43 opposite the ring gear 47 to the end face of the ring gear 47 on the differential case side. The number of gears in the gear train and the number of teeth of each gear can be set appropriately according to the specifications of each vehicle.

[0025] (Sound-absorbing / insulating cover) The sound-absorbing / insulating cover 50 is provided to reduce noise emitted from the electric powertrain 40 and transmitted into the vehicle cabin. The sound-absorbing / insulating cover 50 is attached to the front cross member 32, rear cross member 33, and pair of left and right side members 31 of the suspension member 30 to form a semi-closed space that houses the electric powertrain 40, and is configured to cover the upper side of the electric powertrain 40. The sound-absorbing / insulating cover 50 is positioned so as to protrude above the rear side members 90. The sound-absorbing / insulating cover 50 is formed to have a gap (air gap) between it and the electric powertrain 40. Considering only sound absorption and insulation, it may seem that sound-absorbing / insulating material should be directly attached to the housing C or inverter N of the electric powertrain 40. However, by providing the gap (air gap) as described above, cooling air from an intake 63 (described later) can circulate around and cool the electric powertrain 40. Specifically, the cooling air from the intake 63 is guided by the front side surface of the undercross member 34 toward the rear underside of the housing C of the electric powertrain 40 (a position corresponding to the motor 42), flows through the gap (gap) between the rear underside of the housing C and the upper surface of the undercross member 34, then flows through the gap (gap) between the rear side surface of the housing C and the front side surface of the rear cross member 33, from there flows through the gap (gap) between the front and rear side surfaces and upper surface of the housing C and the sound-absorbing and insulating cover 50, flows through the gap (gap) between the front side surface of the housing C (near the differential 41) and the rear side surface of the front cross member 32, then flows through the gap (gap) between the front underside of the housing C and the undercover 60, and circulates around the housing C to air-cool the entire electric powertrain 40. Therefore, the sound-absorbing and insulating cover 50 can provide both sound-absorbing and air-cooling effects.

[0026] (Undercover) The undercover 60 is disposed below the side sill 10, the battery 20, and the electric powertrain 40. The undercover 60 is attached to the rear end of the battery 20, the lower surfaces of the pair of left and right side members 31 of the suspension member 30, the lower surface of the undercross member 34, the support portion 81 of the inter-pin bar 80 (described later), and the rear bumper 70. The undercover 60 can be configured as a single piece or a predetermined number of pieces in the fore-and-aft direction X of the vehicle. In this embodiment, the undercover 60 is divided into two pieces: a first undercover 61 and a second undercover 62. The division positions of the first undercover 61 and the second undercover 62 are not particularly limited, but in this embodiment, they are provided rearward of the electric powertrain 40 in a plan view.

[0027] The first undercover 61 is provided in front of the motor 42 and has an intake 63 for taking in cooling air. The cooling air taken in through the intake 63 can air-cool the motor 42 and the gear train and differential 41 in front of it, thereby reducing the amount of coolant required for water-cooling the electric powertrain 40. The coolant flows from a radiator (not shown) located at the front of the vehicle through the inside of one of the side sills 10 located at both ends of the battery 20 in the vehicle width direction and enters the inverter N. The coolant then passes through the housing C of the electric powertrain 40, passes through the inside of the other side sill 10, and circulates to the radiator.

[0028] Furthermore, if the arrangement of the motor 42 and the differential 41 were reversed, the distance between the electric powertrain 40 and the battery 20 would be longer by the amount of the intake 63 provided in front of the motor 42. However, with the above configuration, the battery 20, electric powertrain 40, and intake 63 can be arranged compactly in the fore-and-aft direction X of the vehicle.

[0029] Furthermore, the intake port 63 is provided at a position forward of the undercross member 34. As a result, the cooling air taken in from the intake port 63 not only heads directly toward the motor 42, but is also guided by the undercross member 34 and directed upward, thereby improving cooling efficiency.

[0030] As shown in Figure 5, the second undercover 62 is provided behind the motor 42 and has an exhaust port 64 that exhausts the cooling air taken in through the intake port 63. If the exhaust port 64 were not provided, some of the cooling air taken in through the intake port 63 would be exhausted to the outside of the vehicle through the rear wheel house, but because the amount of exhaust is small compared to the amount taken in, a parachute effect would occur, causing air resistance and worsening power consumption (cruising range). Furthermore, the exhaust from the rear wheel house could impede air flow on the side of the vehicle, which could also lead to a worsening Cd value.

[0031] In response to this, by providing an exhaust port 64 at a position rearward of the motor 42, the amount of exhaust can be secured, reducing the parachute effect and reducing emissions from the rear wheel house, thereby preventing the Cd value from deteriorating. The exhaust port 64 is also provided at the rear portion of the second undercover 62. This reduces the pressure difference between the front and rear of the second undercover 62, preventing the second undercover 62 from flapping. The exhaust port 64 also reduces the pressure difference between the top and bottom of the second undercover 62, preventing the second undercover 62 from flapping.

[0032] Furthermore, the cooling air intakes 63 are configured so that their total opening area is smaller than the total opening area of ​​the exhaust ports 64. While a larger total opening area of ​​the intakes 63 is preferable from the viewpoint of the cooling performance of the electric powertrain 40, a smaller total opening area is preferable from the viewpoint of the aerodynamic performance of the undercover 60, which is a trade-off relationship. With the above configuration, the total opening area of ​​the intakes 63 is not unnecessarily large, and the above trade-off relationship can be satisfied. Note that the total opening area of ​​the intakes 63 may be set to the minimum area necessary to allow the cooling air to circulate smoothly through the gaps formed between the electric powertrain 40, the suspension member 30, the undercover 60, and the sound-absorbing and sound-insulating cover 50.

[0033] (Rear Bumper) A rear bumper 70 is connected to the rear of the second undercover 62. The rear bumper 70 has a second exhaust port 71 at its lower part that exhausts the cooling air taken in from the cooling air intake port 63. This ensures a certain amount of exhaust air, similar to the exhaust port 64 of the second undercover 62, reduces the parachute effect, and reduces emissions from the rear wheel house, preventing the Cd value from deteriorating.

[0034] (Inter-pin bar) The inter-pin bar 80 is provided to improve the rigidity of the suspension member 30. As shown in FIG. 4 , the inter-pin bar 80 is formed in a substantially U-shape when viewed from above, and is configured to have a support portion 81 (extending vertically or diagonally) that is fastened to the undercover 60 with a clip or the like. The support portion 81 is provided in the middle of the inter-pin bar 80 in the vehicle width direction Y, and is a wall portion formed of a plate-like member that extends up and down and in the vehicle width direction Y. The support portion 81 supports the connection portion of the first undercover 61 and the second undercover 62 that constitute the undercover 60. The exhaust port 64 provided in the second undercover 62 is configured to be located rearward of the support portion 81 of the inter-pin bar 80 and outward in the vehicle width direction Y.

[0035] The support portions 81 of the inter-pin bar 80 can prevent the second undercover 62 from flapping up and down, and by locating the discharge port 64 on the outside in the vehicle width direction Y, it is possible to prevent a decrease in discharge efficiency due to the support portions 81. Furthermore, attachment points for the first undercover 61 and the second undercover 62 are provided on the support portions 81 extending from the rear of the inter-pin bar 80. This improves the support rigidity of the second undercover 62 and makes it possible to prevent the second undercover 62 from flapping.

[0036] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. In the above, it has been described that the undercover 60 includes the first undercover 61 and the second undercover 62. However, the number of divisions of the undercover does not have to be two as described above, and the undercover may be formed of a single part without being divided.

[0037] The following embodiments are also included within the scope of the present invention: a vehicle structure as defined in claim 1 having the features of claim 2; a vehicle structure as defined in claim 2 having the features of claim 3; a vehicle structure as defined in any one of claims 1 to 3 having the features of claim 4; a vehicle structure as defined in any one of claims 1 to 3 having the features of claim 5; a vehicle structure as defined in claim 4 or claim 5 having the features of claim 6; and a vehicle structure as defined in claim 2 or claim 3 having the features of claim 7.

[0038] 20 Battery, 30 Suspension member, 34 Undercross member, 40 Electric powertrain, 41 Differential, 42 Motor, 50 Sound absorbing / insulating cover, 60 Undercover, 63 Intake port, 64 Outlet port, 70 Rear bumper, 71 Second outlet port, 81 Support portion, X: longitudinal direction, Y: vehicle width direction.

Claims

1. A vehicle structure comprising: a battery placed under the floor of a vehicle; an electric powertrain located under the floor and behind the battery, which drives the rear wheels of the vehicle; and an undercover located below the electric powertrain, wherein the electric powertrain has a motor at the rear and a differential connected to the motor via a gear train at the front, and the undercover is located in front of the motor and has an intake port that can take in cooling air.

2. A vehicle structure as described in claim 1, further comprising a suspension member that supports the electric powertrain, the suspension member supporting the motor at its rear and the differential at its front, and having an undercross member below the motor, the intake being provided at a forward position of the undercross member.

3. The vehicle structure according to claim 2, wherein the suspension members comprise a pair of left and right side members, a front cross member disposed in front of the pair of left and right side members, and a rear cross member disposed rearward of the pair of left and right side members, and further comprising a sound absorbing and insulating cover connected to the pair of left and right side members, the front cross member, and the rear cross member and covering the upper part of the electric powertrain, and wherein there is a gap between the sound absorbing and insulating cover and the electric powertrain.

4. A vehicle structure according to any one of claims 1 to 3, wherein the undercover is provided at a position rearward of the motor and has an outlet that can discharge the cooling air taken in through the intake.

5. A vehicle structure as claimed in any one of claims 1 to 3, further comprising a rear bumper connected to the rear of the undercover, the rear bumper being provided at a lower part and having a second exhaust port for discharging the cooling air taken in from the intake port.

6. A vehicle structure according to claim 4 or 5, wherein the total opening area of ​​the intakes is smaller than the total opening area of ​​the exhaust ports.

7. A vehicle structure according to claim 2 or claim 3, wherein the suspension member has a support portion extending from a rear portion to support the undercover, and the undercover has an exhaust port on the outside of the support portion in the vehicle width direction.

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