Automobile front body structure

Abstract

In order to suppress damage to a motor (31) and a control unit (32) during a frontal collision, the present invention provides an automotive front body structure (1) including a front suspension member (11) that supports a steering rack (23) and an electric power steering device (3) that has the motor (31) and the control unit (32), wherein the motor (31) and the control unit (32) are disposed behind a front cross member (111) of the front suspension member (11) in the vehicle and either above or below the steering rack (23) in the vehicle.

Description

Automobile front body structure

[0001] The present invention relates to a front body structure of an automobile.

[0002] A vehicle underbody structure is known in which an electric power steering device is fixed to a front suspension member that supports a front wheel suspension (see Patent Document 1). In this vehicle underbody structure, the drive section (motor and ECU) of the electric power steering device is located rearward of the front cross member of the front suspension member and forward of the steering rack.

[0003] Japanese Patent Application Laid-Open No. 2018-2006

[0004] However, the above-described conventional vehicle underbody structure has a problem in that, in the event of a frontal collision, the drive section (motor and control unit) of the electric power steering device becomes pinched between the front cross member of the front suspension member and the steering rack, resulting in damage.

[0005] The problem to be solved by the present invention is to provide a front body structure for an automobile in which the motor and control unit of an electric power steering device are not damaged in the event of a frontal collision.

[0006] The present invention solves the above problem by positioning the motor of the electric power steering device that drives the steering rack and its control unit behind the front cross member of the front suspension member and above or below the steering rack.

[0007] According to the present invention, damage to the motor and control unit of the electric power steering device can be suppressed even in the event of a head-on collision.

[0008] Fig. 5 is a schematic diagram showing an example of a steering device included in an embodiment of the front body structure of an automobile according to the present invention. Fig. 6 is a perspective view showing an embodiment of the front body structure of an automobile according to the present invention. Fig. 7 is a perspective view showing an enlarged view of part III in Fig. 2. Fig. 8 is a view seen from an arrow IV in Fig. 3 (a side view of the vehicle). Fig. 9 is a view seen from an arrow V in Fig. 3. Fig. 10 is a perspective view showing an enlarged view of part VI in Fig. 5.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing an example of a steering device 2 included in an embodiment of an automobile front body structure according to the present invention. Known types of electric power steering device 3 included in steering device 2 include a column assist type in which a reducer and a motor are provided in the column section of a steering shaft inside the vehicle cabin to drive the column shaft, a pinion assist type in which a motor is mounted in a pinion case inside the engine compartment to drive a pinion gear that meshes with a rack, and a rack assist type in which a motor and a ball screw are mounted in the rack section of the steering inside the engine compartment to directly drive the rack.

[0010] As described in the Background Art section above, the automobile front body structure 1 of this embodiment is intended to solve the problems that arise when the motor (electric motor) 31 of the electric power steering device 3 and its control unit 32 are mainly disposed on the steering rack 23 of the steering device 2, and is therefore preferably applicable to a pinion-assist or rack-assist electric power steering device 3. In the embodiment of the present invention shown below, the present invention will be described using as an example a steering device 2 that includes a pinion-assist electric power steering device 3 as a representative of these.

[0011] 1 includes a steering wheel 21, a steering shaft 22, a steering rack 23, a tie rod 24, a knuckle 25, a steering wheel 26, a torque sensor 27, and an electric power steering device 3. The electric power steering device 3 of the embodiment is a pinion-assist type electric power steering device, particularly one that is called a double pinion type.

[0012] The steering wheel 21 is connected to a steering shaft 22, and the steering force of the driver input to the steering wheel 21 is transmitted to a steering rack 23 via the steering shaft 22. The tip of the steering shaft 22 is connected to a pinion gear 221 that meshes with a rack gear 232 provided on a rack shaft 231 of the steering rack 23. The meshing structure between the pinion gear 221 of the steering shaft 22 and the rack gear 232 of the rack shaft 231 is a rack and pinion transmission mechanism, which converts the rotational motion of the steering wheel 21 into the linear motion of the rack shaft 231.

[0013] The left and right ends of the rack shaft 231 are connected to the tie rods 24 via joints, and the other end of the tie rods 24 is connected to the knuckle 25 via a joint. As a result, the linear movement of the rack shaft 231 in either the left or right direction is transmitted to the knuckle 25 via the tie rods 24, and as a result, the steered wheels 26 are steered.

[0014] As described above, the electric power steering device 3 of this embodiment is a double-pinion type electric power steering device, and is provided at a position different from the position where the pinion gear 221 of the steering shaft 22 and the rack gear 232 of the rack shaft 231 mesh with each other. The electric power steering device 3 of this embodiment includes a motor 31 and a control unit (also referred to as an electronic control unit ECU) 32 that controls the drive of this motor 31.

[0015] In the electric power steering device 3 of this embodiment, a pinion shaft 34 that is not part of the steering shaft 22 is provided at a position different from the position where the pinion gear 221 of the steering shaft 22 meshes with the rack gear 232 of the rack shaft 231. A pinion gear 341 is provided at the tip of the pinion shaft 34, and this pinion gear 341 is provided so as to mesh with the rack gear 232 of the rack shaft 231. The other end of the pinion shaft 34 is connected to the output shaft of the motor 31 via a reducer 33 that is made up of a worm gear and worm wheel or the like.

[0016] When the driver operates the steering wheel 21, the control unit 32 reads information such as the steering torque, steering angle, and vehicle speed detected by the torque sensor 27, calculates a target value for assist based on this information, and outputs this to the motor 31. As a result, the steering force transmitted from the steering wheel 21 to the rack shaft 231 via the steering shaft 22 and pinion gear 221 is added to the driving force of the motor 31 via the pinion shaft 34 and the reducer 33 to the rack shaft 231.

[0017] Next, an automobile front body structure 1 according to this embodiment will be described. Fig. 2 is a perspective view showing one embodiment of the automobile front body structure 1 according to the present invention, Fig. 3 is an enlarged perspective view of part III in Fig. 2, Fig. 4 is a view taken along arrow IV in Fig. 3 (a side view of the vehicle), Fig. 5 is a view taken along arrow V in Fig. 3, and Fig. 6 is an enlarged perspective view of part VI in Fig. 5. Of the steering device 2 and electric power steering device 3 having the above-described configurations, the rack housing 233 of the steering rack 23 is fixed to a front suspension member 11 provided on the front body of the automobile as shown in Fig. 2, and the electric power steering device 3 is fixed to this rack housing 233.

[0018] The front suspension member 11 of this embodiment includes a front cross member 111 extending in the left-right direction of the vehicle, a pair of side members 112, 113 extending in the front-rear direction of the vehicle from both ends of the front cross member 111, and a rear cross member extending in the left-right direction of the vehicle and connecting the rear ends of the pair of side members 112, 113. The front suspension member 11 of this embodiment is fixed to structural members (such as front side members) that form an engine compartment of an automobile body (not shown).

[0019] 2, the steering rack 23 extends in the left-right direction of the vehicle and is fastened to a pair of side members 112, 113 using bolts. The electric power steering device 3 of this embodiment includes a motor 31, a control unit 32, and a speed reducer 33, and as shown in FIGS. 2 and 5, the casing of the speed reducer 33 is fixed to the left side of the motor casing of the motor 31 with bolts or the like, and the casing of the control unit 32 is fixed to the right side of the motor casing of the motor 31 with bolts or the like.

[0020] As shown in Fig. 5, the casing of the reducer 33 is firmly attached to the rack housing 233 of the steering rack 23 with bolts or the like. That is, as shown in Fig. 5, the casing of the reducer 33 is fixed to the rack housing 233, the casing of the motor 31 is fixed to the casing of the reducer 33, and the casing of the control unit 32 is fixed to the casing of the motor 31, and in this state, the casing of the motor 31 and the casing of the control unit 32 are cantilevered. Therefore, as shown in Figs. 5 and 6, the joint between the casing of the motor 31 and the casing of the control unit 32 is fixed to the rack housing 233 via a bracket 35 with bolts or the like. Although not particularly limited, it is more preferable that the bracket 35 be attached to the rack housing 233 of the steering rack 23 at a position corresponding to or near the center of gravity of the motor 31 and the control unit 32 in the vehicle longitudinal direction.

[0021] In particular, in the automotive front body structure 1 of this embodiment, at least the motor 31 and the control unit 32 of the electric power steering device 3 are disposed rearward of the front cross member 111 of the front suspension member 11 and below the rack housing 233 of the steering rack 23, as shown in Figure 4. Note that the rack housing 233 of the steering rack 23 of this embodiment is disposed above the vehicle relative to the front cross member 111, as shown in Figure 4, and there is space below it, so the motor 31 and the control unit 32 are disposed in this space, but the motor 31 and the control unit 32 may also be disposed above the vehicle relative to the rack housing 233 of the steering rack 23.

[0022] Here, arranging the motor 31 and control unit 32 rearward of the front cross member 111 means that the front ends of the motor 31 and control unit 32 are positioned rearward of the rear end of the front cross member 111. Furthermore, arranging the motor 31 and control unit 32 lower than the rack housing 233 of the steering rack 23 means that the uppermost ends of the motor 31 and control unit 32 are positioned lower than the lower end of the rack housing. Similarly, arranging the motor 31 and control unit 32 higher than the rack housing 233 of the steering rack 23 means that the lowermost ends of the motor 31 and control unit 32 are positioned higher than the upper end of the rack housing.

[0023] 2 to 5 (see particularly FIG. 4), the control unit of this embodiment is disposed so that the front end of the casing of the control unit 32 is located further forward of the vehicle than the front end of the casing of the motor 31. The control unit 32 of this embodiment has a flat casing and vibrates in response to vehicle vibrations, so this arrangement ensures clearance with the steering rack 23 and prevents interference with the steering rack 23.

[0024] As described above, according to the automobile front body structure 1 of this embodiment, the automobile front body structure 1 includes the front suspension member 11 supporting the steering rack 23 and the electric power steering device 3 having the motor 31 and the control unit 32. In this automobile front body structure 1, the motor 31 and the control unit 32 are disposed rearward of the front cross member 111 of the front suspension member 11 and above or below the steering rack 23. Therefore, even in the event of a frontal collision of the automobile, the motor 31 and the control unit 32 of the electric power steering device 3 will not be pinched between the front cross member 111 and the steering rack 23. This prevents the motor 31 and the control unit 32 from being damaged in the event of a frontal collision. Furthermore, disposing the motor 31 and the control unit 32 below the steering rack 23 allows the control unit 32 to be separated from heat sources such as the internal combustion engine or the drive motor, thereby reducing the thermal effects on the control unit 32.

[0025] Furthermore, according to the automobile front body structure 1 of this embodiment, the control unit 32 is disposed so that the front end of the control unit 32 is located further forward of the vehicle than the front end of the motor 31, thereby ensuring clearance with the steering rack 23 and preventing interference with the steering rack 23. Furthermore, by disposing the control unit 32 at the front of the vehicle, the control unit 32 can be separated from heat sources such as the internal combustion engine or the drive motor, and therefore the thermal effects on the control unit 32 can be suppressed.

[0026] Furthermore, according to the automobile front body structure 1 of this embodiment, the control unit 32 is attached to the steering rack 23 via the bracket 35, which makes it possible to suppress vibration of the control unit 32. Furthermore, by adjusting the attachment method of the bracket 35 to adjust the natural value of the vibration of the control unit 32, it is possible to suppress resonance with other vibrating parts.

[0027] Furthermore, according to the automobile front body structure 1 of this embodiment, the bracket 35 is attached to the steering rack 23 at a position corresponding to the center of gravity of the motor 31 and the control unit 32 in the fore-and-aft direction of the vehicle, thereby further suppressing vibration of the control unit 32.

[0028] Furthermore, according to the automobile front body structure 1 of this embodiment, the front suspension member 11 includes a pair of side members 112, 113 extending in the longitudinal direction of the vehicle from both ends of the front cross member 111, and a rear cross member 114 connecting the rear ends of the pair of side members 112, 113, and the steering rack 23 extends in the lateral direction of the vehicle and is supported by the pair of side members 112, 113. Therefore, even if the automobile collides head-on, the motor 31 and control unit 32 of the electric power steering device 3 will not be pinched between the front cross member 111 and the steering rack 23. Therefore, damage to the motor 31 and control unit 32 in the event of a head-on collision can be suppressed.

[0029] Furthermore, according to the automobile front body structure 1 of this embodiment, the steering rack 23 is disposed above the vehicle relative to the front cross member 111, and the motor 31 and control unit 32 are disposed below the vehicle relative to the steering rack 23. Therefore, even if the automobile suffers a frontal collision, the motor 31 and control unit 32 of the electric power steering device 3 will not be pinched between the front cross member 111 and the steering rack 23. This prevents the motor 31 and control unit 32 from being damaged in a frontal collision. Furthermore, since the control unit 32 can be separated from heat sources such as the internal combustion engine or the drive motor, the thermal effects on the control unit 32 can be reduced.

[0030] Furthermore, according to the automobile front body structure 1 of this embodiment, the steering shaft 22 connected to the pinion gear 221 that meshes with the rack gear 232 of the rack shaft 231 is arranged at a first position of the steering rack 23, and at a second position different from the first position of the steering rack 23, the pinion gear 341 of the pinion shaft 34 that does not constitute a steering shaft is meshed with the rack gear 232 of the rack shaft 231, and the output shaft of the motor 31 is connected to the pinion shaft 34 via the reducer 33, so that even in a double-pinion type pinion-assisted electric power steering device 3, damage to the motor 31 and the control unit 32 in the event of a head-on collision can be suppressed.

[0031] DESCRIPTION OF SYMBOLS 1...Front body structure of automobile 11...Front suspension member 111...Front cross member 112, 113...Side member 114...Rear cross member 2...Steering device 21...Steering wheel 22...Steering shaft 221...Pinion gear 23...Steering rack 231...Rack shaft 232...Rack gear 233...Rack housing 24...Tie rod 25...Knuckle 26...Steering wheel 27...Torque sensor 3...Electric power steering device 31...Motor 32...Control unit 33...Reduction gear 34...Pinion shaft 341...Pinion gear 35...Bracket

Claims

1. Front suspension member supporting the steering rack, In an automobile front body structure including an electric power steering system having a motor and a control unit, The motor and the control unit are positioned behind the front cross member of the front suspension member and below the steering rack. The control unit is positioned such that its front end is located in front of the motor, The control unit is mounted to the steering rack via a bracket. The bracket is attached to the steering rack at a position corresponding to the center of gravity of the motor and the control unit in the longitudinal direction of the vehicle, in the front body structure of an automobile.

2. (delete)

3. (delete)

4. (delete)

5. The front suspension member includes a pair of side members extending in the longitudinal direction of the vehicle from both ends of the front cross member, and a rear cross member connecting the rear ends of the pair of side members. The front body structure of an automobile according to claim 1, wherein the steering rack extends in the left-right direction of the vehicle and is supported by the pair of side members.

6. The steering rack is positioned above the front cross member of the vehicle, according to claim 1 or 5, for the front body structure of an automobile.

7. A steering shaft connected to a pinion gear that meshes with the rack gear of the rack shaft is positioned at the first position of the steering rack. A front body structure of an automobile according to any one of claims 1, 5, and 6, wherein, at a second position different from the first position of the steering rack, the pinion gear of a pinion shaft that does not constitute the steering shaft is meshed with the rack gear of the rack shaft, and the output shaft of the motor is connected to the pinion shaft via a reduction gear.