JP2021142773A - Suspension system for in-wheel motor vehicle - Google Patents

Abstract

To suppress noise in a vehicle cabin, and suppress or prevent the disturbance of the attitude of an in-wheel motor vehicle.SOLUTION: A suspension system (7) is a suspension system for an in-wheel motor vehicle (9) in which in-wheel motor driving devices (1) are mounted on at least a pair of wheels (91L, 91R/92L, 92R) arranged so as to face each other along a vehicle width direction. The suspension system (7) includes: air suspensions (51a to 51d) provided between the respective in-wheel motor driving devices (1) and a vehicle body (90); and suspension control means (70) which, when the in-wheel motor driving devices (1) are in a power-running state or in a regenerative state, controls each air suspension to change at least one of a spring constant and a vehicle height.SELECTED DRAWING: Figure 1

Description

The present invention relates to a suspension system for an in-wheel motor vehicle.

Japanese Patent Application Laid-Open No. 2015-214273 (Patent Document 1) includes a housing including a motor and a speed reducer, and in an in-wheel motor unit arranged at a position where an axle and a motor shaft are offset, a portion connecting a suspension to the housing is provided. It is disclosed that by fixing the (ball joint), it is possible to arrange the connecting portion in the wheel.

Japanese Unexamined Patent Publication No. 2013-95309 (Patent Document 2) discloses that an air spring type spension can be applied as a suspension of an in-wheel motor drive device.

Japanese Unexamined Patent Publication No. 2015-214273 (Patent No. 6347149) Japanese Unexamined Patent Publication No. 2013-95309

In an in-wheel motor vehicle in which a motor is mounted in a wheel of a wheel, there are the following problems.

(1) When a gasoline-powered vehicle is an in-wheel motor vehicle, the engine and transmission are attached to the undercarriage, so the mass on the spring is lighter than that of an on-board motor vehicle (vehicle with a motor installed on the vehicle body side). , The unsprung mass becomes heavy. Therefore, as shown in FIGS. 14A and 14B, the unsprung resonance frequency Fa is lower and the unsprung resonance frequency Fb is higher in the in-wheel motor vehicle than in the onboard vehicle. ..

In a general gasoline vehicle, the resonance frequency on the spring is 1 Hz, and the resonance frequency under the spring is 10 Hz. As shown in FIG. 14 (B), when the resonance frequencies above and below the spring approach, the vibration between the resonance points (frequency Fa-Fb) increases, and the meshing of the gears of the in-wheel motor drive or the meshing of the motor Vibration due to the resonance of forced vibration is easily transmitted to the vehicle body via the suspension. In addition, the meshing of the gears of the in-wheel motor drive device or the forced vibration of the motor is amplified under driving conditions such as starting (acceleration) from the vehicle stopped state, running at extremely low speed, and starting on a slope, so that the driver can use it. I feel uncomfortable.

(2) As shown in Patent Document 1, the suspension connected to the in-wheel motor drive device is generally of the coil spring type. However, in the case of the coil spring type suspension, as shown in the schematic view of FIG. 15, the vibration from the in-wheel motor drive device 100 is transmitted to the spring 150, and the vibration is amplified with the resonance of the spring 150. There is a risk that the noise inside the vehicle body 90 (inside the vehicle) will worsen.

(3) In an in-wheel motor vehicle, the driving force of the motor is transmitted to the ground contact point of the tire on the outer peripheral portion of the wheel. Therefore, for example, in a four-wheel drive type in-wheel motor vehicle, as shown in FIG. 16 (A), an in-wheel motor drive device (not shown) mounted on the wheels (front wheels and rear wheels) 91 and 92 is used. When the force is applied, a force for lowering the vehicle body 90 is generated at the instantaneous rotation center 91c of the front wheels 91, and a force for lifting the vehicle body 90 is generated at the instantaneous rotation center 92c of the rear wheels 92. Then, at the time of power running, a phenomenon occurs in which the front side of the vehicle body 90 sinks and the rear side is lifted. On the contrary, as shown in FIG. 16B, when the in-wheel motor drive device mounted on the wheels 91 and 92 regenerates, a phenomenon occurs in which the front side of the vehicle body 90 is lifted and the rear side is sunk. If the posture of the vehicle body 90 is disturbed in this way, the driver may be uncomfortable.

Further, in an in-wheel motor vehicle, in order to improve turning performance during turning, as shown in FIG. 17, the in-wheel drive device on the turning outer ring side (right wheels 91R and 92R in FIG. 17) is powered and turned. Left and right independent control is performed by regenerating the in-wheel drive device on the inner wheel side (left wheels 91L and 92L in FIG. 17). Therefore, since the roll is promoted when turning, the vehicle body 90 may tilt and the posture of the vehicle 9 may be disturbed as shown in FIG.

On the other hand, in the suspension system of Patent Document 2, the elastic coefficient of the air spring or the like is changed in order to reduce the vibration peculiar to the in-wheel motor vehicle as shown in the above problems (1) and (2). A possible suspension will be connected to the in-wheel motor drive. However, in the suspension system of Patent Document 2, it is difficult to solve the above problem (3) because the elastic modulus is changed when traveling straight at a constant speed. That is, it is difficult to suppress the disturbance of the posture of the in-wheel motor vehicle.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to suppress noise in a vehicle interior and to suppress or prevent disturbance of the posture of an in-wheel motor vehicle. To provide a suspension system.

A suspension system according to an aspect of the present invention is a suspension system for an in-wheel motor vehicle in which an in-wheel motor drive is mounted on at least a pair of wheels arranged so as to face each other along the vehicle width direction. .. The in-wheel motor drive device includes a motor unit that drives the wheels, a wheel hub bearing unit that is attached to the wheel, and a deceleration unit that decelerates the rotation of the motor unit and transmits it to the wheel hub bearing unit. This suspension system controls the air suspension provided between each in-wheel motor drive and the vehicle body, and the air suspension when the in-wheel motor drive is driven or regenerated, to determine the spring constant and vehicle height. It is provided with suspension control means for changing at least one of them.

Preferably, the in-wheel motor drive is mounted on at least the front wheels.

In this case, the suspension system further includes a detection means for detecting the running state of the vehicle, and the suspension control means sets the spring constant of the air suspension arranged on the front wheels from the reference level when the turning is detected by the detection means. It is also desirable to increase.

Further, the suspension control means may set the spring setting of the air suspension arranged on the front wheels to be higher than the reference level when the detection means detects straight movement and the in-wheel motor drive device runs or regenerates. desirable.

The in-wheel motor drive may also be mounted on the rear wheels. In this case, it is desirable that the suspension control means keeps the spring constant of the air suspension arranged on the rear wheels at the reference level when the turning is detected by the detection means.

Further, when the suspension control means detects straight movement by the detection means and the in-wheel motor drive device runs or regenerates, the spring constants of the air suspensions arranged on both the front wheels and the rear wheels are set from the reference level. May also be higher.

Further, it is also desirable that the suspension control means raises the vehicle height of the air suspension on the turning inner ring side to be higher than the vehicle height of the air suspension on the turning outer ring side when the turning is detected by the detecting means.

Preferably, the suspension control means raises the vehicle height of the air suspension arranged on the front wheels to a level higher than the reference level when the detection means detects the straight movement and the in-wheel motor drive device drives the vehicle. When straight running is detected and the in-wheel motor drive device regenerates, the vehicle height of the air suspension arranged on the front wheels is lowered below the reference level.

When the in-wheel motor drive device is also mounted on the rear wheels, the suspension control means maintains the vehicle height of the air suspension arranged on the rear wheels at the reference level when turning is detected by the detection means. You may.

The suspension control means sets the vehicle height of the air suspension arranged on the front wheels higher than the vehicle height of the air suspension arranged on the rear wheels when the detection means detects that the vehicle is moving straight and the in-wheel motor drive device drives the vehicle. The height of the air suspension placed on the front wheels is higher than the height of the air suspension placed on the rear wheels when the vehicle is detected to go straight by the detection means and the in-wheel motor drive device is regenerated. It is also desirable to lower it.

According to the present invention, it is possible to suppress noise in the vehicle interior and suppress or prevent disturbance of the posture of the in-wheel motor vehicle.

It is a figure which shows typically the in-wheel motor vehicle which concerns on embodiment of this invention. It is a developed sectional view schematically showing the internal structure of the in-wheel motor drive device mounted on the in-wheel motor vehicle which concerns on embodiment of this invention. It is sectional drawing of the in-wheel motor drive device along the line III-III of FIG. It is a schematic diagram which looked at the strut type air suspension in embodiment of this invention from the inside in the vehicle width direction. It is a schematic diagram which looked at the strut type air suspension in embodiment of this invention from the front or the rear. It is a figure which shows typically the circuit structure example of the air suspension. It is a block diagram which shows typically the functional structure of the suspension system for the in-wheel motor vehicle which concerns on embodiment of this invention. It is a flowchart which shows the spring constant adjustment processing in embodiment of this invention. It is a flowchart which shows the vehicle height adjustment processing in embodiment of this invention. It is a graph which shows the resonance frequency on the spring and under the spring of the in-wheel motor vehicle which concerns on this embodiment. (A) to (C) are diagrams schematically showing an arrangement example of a compressor of an air suspension in an in-wheel motor vehicle according to an embodiment of the present invention. It is a schematic view of a double wishbone type air suspension seen from the inside in the vehicle width direction. It is a schematic diagram which looked at the double wishbone type air suspension from the front or the rear. It is a graph which shows the difference of the resonance frequency of an in-wheel motor vehicle and an on-board motor vehicle. It is a schematic diagram conceptually showing a problem when a coil spring type suspension is applied. (A) and (B) are schematic diagrams conceptually showing the force applied to the vehicle body when the in-wheel motor drive device runs and regenerates in the in-wheel motor vehicle. In-wheel motor It is a schematic diagram conceptually showing that the in-wheel motor drive devices of the left and right wheels are independently controlled when the vehicle turns. It is a schematic view seen from the XVIII direction of FIG. 17, and is the figure which conceptually shows the force applied to the vehicle body when an in-wheel motor vehicle turns.

Embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

With reference to FIG. 1, the in-wheel motor vehicle (hereinafter, may be abbreviated as “vehicle”) 9 according to the present embodiment is, for example, a four-wheel drive vehicle, with front wheels 91L, 91R and rear wheels 92L, 92R. An in-wheel motor drive device 1 is mounted on each of the above. The front wheels 91L and 91R are wheels arranged in pairs on the front side of the vehicle 9, and the rear wheels 92L and 92R are wheels arranged in pairs on the rear side of the vehicle 9. The front wheels 91L and 91R and the rear wheels 92L and 92R are arranged so as to face each other along the vehicle width direction (left-right direction) of the vehicle 9, respectively. It is assumed that the front wheels 91L and the rear wheels 92L located on the left side in the drawing are arranged on the left side of the vehicle body 90, and the front wheels 91R and the rear wheels 92R located on the right side in the drawing are arranged on the right side of the vehicle body 90. ..

The in-wheel motor drive device 1 mounted on each wheel is connected to the vehicle body 90 via an air spring type suspension (suspension device). Specifically, the front wheels 91L and 91R are provided with air suspensions 51a and 51b, respectively, and the rear wheels 92L and 92R are provided with air suspensions 51c and 51d, respectively.

In the following description, when it is not necessary to distinguish the left and right of the front wheels 91L and 91R, these are referred to as front wheels 91, and when it is not necessary to distinguish the left and right of the rear wheels 92L and 92R, these are referred to as rear wheels 92. It is called. When it is not necessary to distinguish between the front wheels 91 and the rear wheels 92, these are referred to as wheels 91. Similarly, when it is not necessary to distinguish between the four air suspensions 51a to 51d, these are referred to as air suspensions 51.

(About the basic configuration example of the in-wheel drive device)
A basic configuration example of the in-wheel motor drive device 1 according to the embodiment of the present invention will be described with reference to FIGS. 2 to 3. FIG. 2 is a developed cross-sectional view showing the in-wheel motor drive device 1 according to the embodiment of the present invention. In FIG. 2, the right side of the paper surface represents the inside in the vehicle width direction (inboard side), and the left side of the paper surface represents the outside in the vehicle width direction (outboard side). The cross section shown in FIG. 2 is a developed plane in which a plane including the axis M and the axis N shown in FIG. 3 and a plane including the axis N and the axis O are connected in this order.

FIG. 3 is a schematic cross-sectional view showing the inside of the in-wheel motor drive device 1, and shows a state in which the in-wheel motor drive device 1 is cut in FIGS. 3 to III and the cross section is viewed in the direction of an arrow. In FIG. 3, each gear is represented by a tooth tip circle in order to avoid complication of drawing. In FIG. 3, the right side of the paper represents the front of the vehicle, the left side of the paper represents the rear of the vehicle, the upper side of the paper represents the upper part of the vehicle, and the lower side of the paper represents the lower part of the vehicle. In FIG. 3, the inside in the vehicle width direction is viewed from the outside in the vehicle width direction in the axis O direction.

The in-wheel motor drive device 1 decelerates the rotation of the wheel hub bearing portion 11 provided in the center of the wheel 91, the motor portion 21 for driving the wheel 91, and the motor portion 21 and transmits the deceleration to the wheel hub bearing portion 11. A unit 31 is provided. The motor unit 21 and the deceleration unit 31 are arranged offset from the axis O of the wheel hub bearing unit 11. The axis O extends in the vehicle width direction and coincides with the axle. Regarding the position in the axis O direction, the wheel hub bearing portion 11 is arranged on one axis direction (outboard side) of the in-wheel motor drive device 1, and the motor portion 21 is arranged on the other axis direction (inboard side) of the in-wheel motor drive device 1. The deceleration unit 31 is arranged on one side of the motor unit 21 in the axial direction, and the axial position of the deceleration unit 31 overlaps with the axial position of the wheel hub bearing portion 11.

As shown in FIG. 3, the in-wheel motor drive device 1 is housed in the inner space region of the wheel W of the wheel 91. However, the motor unit 21 may protrude inward in the vehicle width direction from the inner space region of the wheel W.

The wheel hub bearing portion 11 is, for example, a rotating inner ring / fixed outer ring, and the inner ring 12 as a rotating wheel (hub ring) coupled to the wheel W of the wheel 91 and a fixed ring coaxially arranged on the outer diameter side of the inner ring 12. The outer ring 13 and a plurality of rolling elements 14 arranged in the annular space between the inner ring 12 and the outer ring 13 are provided.

With reference to FIG. 2, the outer ring 13 penetrates the opening 39p formed in the front portion 39f of the main body casing 39. The main body casing 39 refers to a casing including the outer shell of the deceleration unit 31, and accommodates the rotating element of the deceleration unit 31. The front portion 39f is a casing wall portion that covers one end of the deceleration portion 31 in the axis O direction of the main body casing 39.

The outer ring 13 is fixed to the front portion 39f of the main body casing 39 via the hub attachment 42. The outer ring 13 has a protruding portion 13g that protrudes in the radial direction, and the protruding portion 13g is attached and fixed to the hub attachment 42 by the first bolt 43. The hub attachment 42 is attached and fixed to the main body casing 39 by the second bolt 44.

The inner ring 12 is a cylindrical body longer than the outer ring 13, and is passed through the central hole of the outer ring 13. A hub flange 12f is formed at one end of the inner ring 12 protruding from the outer ring 13 to the outside of the in-wheel motor drive device 1 in the axis O direction. The inner ring 12 is coupled to the wheel W by the hub flange 12f and rotates integrally with the wheel 91.

A plurality of rows of rolling elements 14 are arranged in the annular space between the inner ring 12 and the outer ring 13. The outer peripheral surface of the inner ring 12 at the center of the axis O direction constitutes the inner raceway surface of the plurality of rolling elements 14 arranged in the first row. An inner raceway ring 12r is fitted on the outer periphery of the other end of the inner ring 12 in the O-axis direction. The outer peripheral surface of the inner raceway ring 12r constitutes the inner raceway surface of the plurality of rolling elements 14 arranged in the second row. The inner peripheral surface of one end of the outer ring 13 in the O-axis direction constitutes the outer raceway surface of the rolling elements 14 in the first row. The inner peripheral surface of the other end of the outer ring 13 in the O-axis direction constitutes the outer raceway surface of the rolling elements 14 in the second row. The sealing material 16 is further interposed in the annular space between the inner ring 12 and the outer ring 13. The sealing material 16 seals both ends of the annular space to prevent dust and foreign matter from entering. The output shaft 38 of the speed reduction unit 31 is inserted into the center hole at the other end of the inner ring 12 in the O-axis direction and fitted. Such fitting is spline fitting or serration fitting.

As shown in FIG. 2, the motor unit 21 has a motor rotating shaft 22, a rotor 23, a stator 24, and a motor casing 29, and is sequentially arranged from the axis M of the motor unit 21 to the outer diameter side in this order. The motor unit 21 is an inner rotor or outer stator type radial gap motor, but may be another type of electric motor. The motor casing 29 surrounds the outer circumference of the stator 24. One end of the motor casing 29 in the axis M direction is coupled to the back surface portion 39b of the main body casing 39. The other end of the motor casing 29 in the M direction along the axis is sealed with a plate-shaped motor casing cover (hereinafter referred to as "rear cover") 29v. The back surface portion 39b is a casing wall portion that covers the other end of the deceleration portion 31 in the axis M direction (axis line O direction) of the main body casing 39.

The main body casing 39 and the motor casing 29 form a casing 10 that forms an outer shell of the in-wheel motor drive device 1. When it is not necessary to distinguish between the main body casing 39 and the motor casing 29 in the following description, it is simply referred to as casing 10.

The stator 24 includes a cylindrical stator core 25 and a coil 26 wound around the stator core 25. The stator core 25 is formed by laminating ring-shaped steel plates in the axis M direction.

Both ends of the motor rotating shaft 22 are rotatably supported by the back surface portion 39b of the main body casing 39 and the rear cover 29v of the motor portion 21 via rolling bearings 27 and 28. Most of the motor rotating shaft 22 except for one end 22e in the axial direction is arranged in the motor casing 29. One end 22e in the axial direction is arranged in the main body casing 39. That is, the motor rotating shaft 22 is housed in the casing 10 of the in-wheel motor driving device 1.

The axis M, which is the center of rotation of the motor rotating shaft 22 and the rotor 23, extends parallel to the axis O of the wheel hub bearing portion 11. Specifically, the motor portion 21 is offset so as to be separated from the axis O of the wheel hub bearing portion 11 toward the front side of the vehicle.

The speed reduction unit 31 includes an input shaft 32 coaxially coupled to the motor rotation shaft 22 of the motor unit 21, an input gear 33 coaxially provided on the outer peripheral surface of the input shaft 32, and a plurality of intermediate gears 34 and 36, and intermediate gears 34 and 36 thereof. An intermediate shaft 35 connected to the center of the gears 34 and 36, an output shaft 38 connected to the inner ring 12 of the wheel hub bearing portion 11, and an output gear 37 coaxially provided on the outer peripheral surface of the output shaft 38, and a plurality of these. It has a main body casing 39 for accommodating gears and a rotating shaft. Since the main body casing 39 forms the outer shell of the deceleration unit 31, it is also referred to as a deceleration unit casing.

The input gear 33 is a helical gear with external teeth. The input shaft 32 has a hollow structure, and one end portion 22e of the motor rotating shaft 22 in the axial direction is inserted into the hollow hole 32h to perform spline fitting or serration fitting so that the motor rotating shaft 22 cannot rotate relative to each other. The input shaft 32 is rotatably supported on both ends of the input gear 33 by the front portion 39f and the back portion 39b of the main body casing 39 via rolling bearings 32a and 32b.

The axis N, which is the center of rotation of the intermediate shaft 35 of the speed reduction unit 31, extends parallel to the axis O. Both ends of the intermediate shaft 35 are rotatably supported by the front portion 39f and the back portion 39b of the main body casing 39 via rolling bearings 35a and 35b. A first intermediate gear 34 is coaxially provided at the other end of the intermediate shaft 35 in the N direction of the axis. A second intermediate gear 36 is coaxially provided in the central region of the intermediate shaft 35 in the N direction of the axis.

The first intermediate gear 34 and the second intermediate gear 36 are helical gears having external teeth, and the diameter of the first intermediate gear 34 is larger than the diameter of the second intermediate gear 36. The large-diameter first intermediate gear 34 is arranged on the other side of the second intermediate gear 36 in the N direction of the axis and meshes with the small-diameter input gear 33. The small-diameter second intermediate gear 36 is arranged on one side of the first intermediate gear 34 in the N direction of the axis and meshes with the large-diameter output gear 37.

As shown in FIG. 3, the axis N of the intermediate axis 35 is arranged above the axis O and the axis M. Further, the axis N of the intermediate shaft 35 is arranged in front of the vehicle with respect to the axis O and behind the vehicle with respect to the axis M. The speed reduction unit 31 is a three-axis parallel shaft gear speed reducer having axes O, N, and M arranged at intervals in the front-rear direction of the vehicle and extending in parallel with each other, and has a two-speed shift.

The output gear 37 is a helical gear with external teeth, and is coaxially provided at the center of the axis O of the output shaft 38. The output shaft 38 extends along the axis O. One end of the output shaft 38 in the O-axis direction is inserted into the center hole of the inner ring 12 and fitted so as not to rotate relative to each other. The central portion of the output shaft 38 in the O-direction is rotatably supported by the front portion 39f of the main body casing 39 via the rolling bearing 38a. The other end of the output shaft 38 in the axis O direction is rotatably supported by the back surface portion 39b of the main body casing 39 via the rolling bearing 38b.

As shown in FIG. 2, the reduction gear 31 includes a small-diameter drive gear and a large-diameter driven gear, that is, an input gear 33 and a first intermediate gear 34, and a second intermediate gear 36 and an output gear 37. The rotation of the input shaft 32 is decelerated and transmitted to the output shaft 38. The rotating element from the input shaft 32 to the output shaft 38 of the speed reducing unit 31 constitutes a drive transmission path that transmits the rotation of the motor unit 21 to the inner ring 12.

The main body casing 39 includes a cylindrical portion in addition to the above-mentioned front portion 39f and back portion 39b. The cylindrical portion covers the internal parts of the speed reducing portion 31 so as to surround the axes O, N, and M extending in parallel with each other. The plate-shaped front portion 39f covers the internal component of the deceleration portion 31 from one side in the axial direction and is coupled to one end of the cylindrical portion. The plate-shaped back surface portion 39b covers the internal component of the speed reducing portion 31 from the other side in the axial direction and is coupled to the other end of the cylindrical portion. The back surface portion 39b of the main body casing 39 is also a partition wall that is coupled to the motor casing 29 and partitions the internal space of the deceleration unit 31 and the internal space of the motor unit 21. The motor casing 29 is supported by the main body casing 39 and projects from the main body casing 39 to the other side in the axial direction (inside in the vehicle width direction).

The main body casing 39 partitions the internal space of the deceleration unit 31, and accommodates all the rotating elements (rotating shaft and gears) of the deceleration unit 31 in the internal space. Lubricating oil that lubricates the motor unit 21 and the speed reduction unit 31 is stored in the oil storage unit 30 that occupies the lower part of the internal space of the main body casing 39.

When electric power is supplied to the coil 26 described above from the outside of the in-wheel motor drive device 1, the rotor 23 of the motor unit 21 rotates, and the rotation is output from the motor rotation shaft 22 to the reduction unit 31. The speed reduction unit 31 decelerates the rotation input from the motor unit 21 to the input shaft 32, and outputs the rotation from the output shaft 38 to the wheel hub bearing unit 11. The inner ring 12 of the wheel hub bearing portion 11 rotates at the same rotation speed as the output shaft 38, and drives the wheel 91 attached and fixed to the inner ring 12.

The in-wheel motor drive device 1 having the above configuration is mounted on each wheel 91 of the vehicle 9 shown in FIG. The internal configuration of the in-wheel motor drive device 1 is also common to the front wheels 91 and the rear wheels 92, and typically, the output characteristics of the motor unit 21 and the reduction ratio of the reduction unit 31 are related to the front wheels 91 and the rear wheels 92. Is the same.

In the present embodiment, an example is shown in which the reduction gear 31 is a parallel 3-axis gear reducer having axis lines O, N, and M extending in parallel with each other, but parallel with a plurality of gears meshing with each other. If it is a shaft type gear reducer, it may have two or four shafts or more. Alternatively, the reduction gear 31 may be composed of a reduction gear other than the parallel shaft gear reduction gear.

(About air suspension)
4 and 5 are diagrams schematically showing an air suspension 51 connected to the in-wheel motor drive device 1. FIG. 4 shows a state in which the wheels (front wheels) 91 are viewed from the inside in the vehicle width direction, and FIG. 5 shows a state in which the wheels (front wheels) 91 are viewed from the rear of the vehicle.

The air suspension 51 according to the present embodiment is, for example, a MacPherson strut type suspension, which includes a damper 52 extending in the vertical direction, an air spring 53, a lower arm 54 extending in the vehicle width direction, and a tie rod 55.

The air suspension 51 is fixed to the in-wheel motor drive device 1 via, for example, a suspension bracket 41. The suspension bracket 41 is attached to a region of the inner end surface of the casing 10 in the vehicle width direction, which is located behind the motor portion 21 (motor casing 29). The suspension bracket 41 includes a main body 41d fixed to the main body casing 39 by bolts 45, a damper connecting portion 41a connected to the lower end of the damper 52, and a lower arm connecting to the outer end of the lower arm 54 in the vehicle width direction. A portion (not shown) and a tie rod connecting portion 41c connected to the outer end portion of the tie rod 55 in the vehicle width direction are integrally included.

FIG. 6 is a diagram schematically showing a circuit configuration example of the air suspension 51. The air suspension 51 has an air chamber 61 formed by a rubber diaphragm and a rolling guide, and has a structure in which air is filled therein. The air chamber 61 is provided around the rod 62 of the damper 52 and constitutes the air spring 53. Since the elasticity of the air spring 53 is realized by rubber and air, the air spring 53 has less natural vibration than the coil spring. Therefore, in the vehicle 9, the vibration via the spring is suppressed, and there is an effect that the noise inside the vehicle can be reduced.

Further, in a vehicle to which a coil spring is applied, it is necessary to lay out the electric cable extending from the in-wheel motor drive device to the vehicle body so as not to be sandwiched between the coil springs, whereas in the vehicle 9, it is imagined in FIG. As shown by the line, the electric cable (power line or signal line) 81 extending from the in-wheel motor drive device 1 can be routed to the damper 52 and the air spring 53 and guided to the vehicle body 90 side.

With reference to FIG. 6 again, the air compressed by the compressor 64 driven by the motor 63 is guided to the supply valve 65. By opening and closing the supply valve 65, the amount of air in the air chamber 61 is adjusted while keeping the capacity of the air chamber 61 constant. As a result, the vehicle height can be made variable. Specifically, when raising the vehicle height, air is supplied to the air chamber 61 to increase the air volume, and when lowering the vehicle height, air is removed from the air chamber 61 to reduce the air volume.

A separately placed sub tank 66 is connected to the air chamber 61, and the capacity of air (the size of the air chamber) is adjusted by opening and closing the cut valve 67. As a result, the spring constant can be made variable. Specifically, when the spring constant is low (soft), the cut valve 67 is opened to increase the volume of the air spring 53, and when the spring constant is high (hard), the cut valve 67 is closed. The volume of the air spring 53 is controlled to be reduced.

Such an air suspension 51 is provided between the in-wheel motor drive device 1 mounted on each wheel 91 and the vehicle body 90. As shown in FIG. 1, each air suspension 51 is controlled by a control device (suspension control means) 70 provided on the vehicle body 90 side. The control device 70 controls the air suspension 51 to change at least one of the spring constant and the vehicle height when the in-wheel motor drive device 1 mounted on the wheels 91 powers or regenerates. Note that "power running" refers to a state in which the motor unit 21 is driven in a state where the speed and torque have the same sign, such as when the vehicle 9 is accelerating, and "regeneration" refers to a state in which the vehicle 9 is decelerated (braking). , The state in which the motor unit 21 is driven with the speed and torque having opposite signs. A state in which neither is the case while the vehicle is running is called "coasting".

FIG. 7 is a block diagram schematically showing the functional configuration of the suspension system 7 for the in-wheel motor vehicle 9. The suspension system 7 includes the above-mentioned control device 70, air suspensions 51a to 51d, and a traveling state detecting unit (detecting means) 71 for detecting the traveling state of the vehicle 9.

The traveling state detection unit 71 detects the traveling state by detecting, for example, the steering wheel operation and the pedal operation of the driver. The running state includes at least a straight running state and a turning state.

The control device 70 functions as a suspension control means, and controls the air suspensions 51a to 51d according to the detection result by the traveling state detection unit 71. The control device 70 is realized by a computer including a memory and a processor. The method of controlling the air suspensions 51a to 51d by the control device 70 will be described in detail later.

(About the operation of the suspension system)
The operation of the suspension system 7 will be described with reference to FIGS. 8 to 9. FIG. 8 is a flowchart showing the spring constant adjustment process according to the present embodiment. FIG. 9 is a flowchart showing the vehicle height adjustment process according to the present embodiment. These processes are executed by the control device 70. The spring constant adjustment process and the vehicle height adjustment process may be performed in parallel (simultaneously), or only one of them may be performed. In the latter case, one of the spring constant adjustment process and the vehicle height adjustment process may be performed according to the mode selected by the user. In this case, the suspension system 7 further includes an operation unit (not shown) for allowing the user to select either the spring constant adjustment mode or the vehicle height adjustment mode.

-Spring constant adjustment process The spring constant adjustment process shown in FIG. 8 is started when the vehicle 9 is in a runnable state (when the power is turned on). In this embodiment, the spring constant can be changed in at least two steps, low level and high level. At the start of this process, the spring constants of all the wheels (front wheels 91 and rear wheels 92) are set to a low level (soft). That is, the reference level of the spring constant is a low level. When the spring constant is at the reference level, the cut valve 67 of each air suspension 51 is in the open state, and the capacity of the air spring 53 is set large.

With reference to FIG. 8, the control device 70 determines the traveling state of the vehicle 9 detected by the traveling state detecting unit 71 (step S11). If the vehicle 9 is traveling straight, the traveling state is determined to be a straight traveling state, and the process proceeds to step S13. If the vehicle 9 is turning, the traveling state is determined to be the turning state, and the process proceeds to step S19.

In step S13, the control device 70 determines whether or not the traveling state of the vehicle 9 is further coasting. That is, it is determined whether or not the vehicle 9 is traveling straight at a constant speed. If the running state of the vehicle 9 is straight and coasting, that is, if the in-wheel motor driving device 1 is not in the power running or regenerative state (YES in step S13), all the spring constants of the front wheels 91 and the rear wheels 92 are used as reference. The level (low level) is set (step S15). That is, the spring constants of all the air suspensions 51a to 51d are controlled to be the reference level.

On the other hand, when the traveling state of the vehicle 9 is not in the coasting state, that is, when the in-wheel motor driving device 1 is in the power running or regenerative state (NO in step S13), all the spring constants of the front wheels 91 and the rear wheels 92 are referred to. Raise it above the level (step S17). That is, the spring constant is changed from low level to high level. More specifically, the control device 70 controls to reduce the capacity of the air spring 53 by closing the cut valve 67 of each air suspension 51. As a result, the air springs 53 are in a hard state on both the front wheels 91 and the rear wheels 92, so that the inclination of the vehicle body 90 in the front-rear direction as shown in FIGS. 16A and 16B can be suppressed. As a result, the driver's discomfort can be reduced.

In step S19, the control device 70 raises only the spring constant of the front wheels 91 above the reference level regardless of the turning direction of the vehicle 9. That is, the spring constant of the rear wheel 92 is not changed and remains at the reference level. In this case, the control device 70 closes the cut valves 67 of the air suspensions 51a and 51b arranged on the front wheels 91, and controls to reduce the capacity of the air spring 53. As a result, the air springs 53 of the air suspensions 51a and 51b of the front wheels 91 are in a hard state, so that the inclination of the vehicle body 90 in the left-right direction as shown in FIG. 18 can be suppressed.

In the present embodiment, the spring constant of the rear wheels 92 is not changed when the vehicle 9 turns (in step S19), but the spring constant of the rear wheels 92 is not limited, and the spring constant of the rear wheels 92 is the spring constant of the front wheels 91. It should be lower than.

As described above, by selecting the air spring that changes the spring constant from the air suspensions 51a to 51d according to the traveling state of the vehicle 9, it is possible to suppress or prevent the posture disorder of the vehicle body 90.

Further, when the vehicle 9 is stopped, the spring constants of all the air suspensions 51 are set lower than those of the coil springs, so that the resonance frequency (Fa') on the springs (Fa') is conceptually shown in the graph of FIG. ) Can be lower than the resonance frequency Fa of the in-wheel motor vehicle to which the coil spring type suspension is applied. That is, the resonance frequencies above and below the spring can be separated. Then, in order to change the spring constant from a low level to a high level (the spring constant gradually increases) under traveling conditions such as acceleration from a vehicle stopped state, traveling at an extremely low speed, and starting on a slope, the deceleration unit 31 is moved. Since the meshing of the constituent gears or the overlap between the forced vibration component of the motor unit 21 and the resonance frequency under the spring can be shifted, unpleasant vibration can be reduced. Therefore, the noise in the vehicle interior can be suppressed.

It should be noted that the level of the spring constant may be finely changed according to the traveling speed of the vehicle 9 during power running in the straight running state.

-Vehicle height adjustment process The vehicle height adjustment process shown in FIG. 9 is also started when the vehicle 9 is ready to travel (when the power is turned on). In the present embodiment, the vehicle height can be changed in at least three stages of low level, medium level, and high level. At the start of this process, the vehicle heights of all the wheels (front wheels 91 and rear wheels 92) are set to a medium level. In other words, the standard level of vehicle height is medium level.

With reference to FIG. 9, the control device 70 determines the traveling state of the vehicle 9 detected by the traveling state detecting unit 71 (step S21). If the vehicle 9 is traveling straight, the traveling state is determined to be a straight traveling state, and the process proceeds to step S23.

In step S23, the control device 70 determines whether or not the traveling state of the vehicle 9 is further coasting. That is, it is determined whether or not the vehicle 9 is traveling straight at a constant speed. If the traveling state of the vehicle 9 is straight and coasting, that is, if the in-wheel motor driving device 1 is not in the power running or regenerative state (YES in step S23), all the vehicle heights of the front wheels 91 and the rear wheels 92 are used as a reference. The level (medium level) is set (step S25). That is, all the air suspensions 51a to 51d are controlled so that the vehicle height becomes the reference level.

On the other hand, when the traveling state of the vehicle 9 is in a straight running state and the in-wheel motor driving device 1 is in a power running state (NO in step S23), the vehicle height of the front wheels 91 is changed from the medium level (reference level) to the high level. At the same time as changing to the level, the vehicle height of the rear wheels 92 is changed from the medium level (reference level) to the low level (step S26). Specifically, the control device 70 controls to increase the opening degree of the supply valves 65 of the air suspensions 51a and 51b provided on the pair of front wheels 91, respectively, and increase the amount of air in each of the air springs 53. Further, the opening degree of the supply valve 65 of the air suspensions 51c and 51d provided on each of the pair of rear wheels 92 is reduced to reduce the amount of air in each of the air springs 53. As a result, as shown in FIG. 16A, even if an downward force is generated at the instantaneous rotation center 91c of the front wheels 91 and an upward force is generated at the instantaneous rotation center 92c of the rear wheels 92, the vehicle body 90 It is possible to suppress tilting in the front-back direction.

When the traveling state of the vehicle 9 is in a straight running state and the in-wheel motor driving device 1 is in a regenerative state (NO in step S23), the control opposite to that in the case of power running is performed. That is, the vehicle height of the front wheels 91 is changed from the medium level (reference level) to the low level, and the vehicle height of the rear wheels 92 is changed from the medium level (reference level) to the high level (step S27). As a result, as shown in FIG. 16B, even if an upward force is generated at the instantaneous rotation center 91c of the front wheels 91 and a downward force is generated at the instantaneous rotation center 92c of the rear wheels 92, the vehicle body 90 It is possible to suppress tilting in the front-back direction.

In the present embodiment, in step S26, the vehicle height of the front wheels 91 is changed from the medium level to the high level, and the vehicle height of the rear wheels 92 is changed from the medium level to the low level, but this is limited. Instead, the vehicle height of the front wheels 91 should be higher than the vehicle height of the rear wheels 92. Similarly, in step S27, the vehicle height of the front wheels 91 is changed from the medium level to the low level, and the vehicle height of the rear wheels 92 is changed from the medium level to the high level. The vehicle height of 92 may be higher than the vehicle height of the front wheels 91.

As a result of the determination of the traveling state in step S21, when it is determined that the traveling state of the vehicle 9 is a turning state, if the turning direction is "left turning", the process proceeds to step S28 and the turning direction is "right turning". If it is "times", the process proceeds to step S29.

In step S28, the control device 70 changes the vehicle height of the left front wheel 91L from the reference level to a low level while maintaining the vehicle height of the rear wheels 92 at the reference level, and raises the vehicle height of the right front wheel 91R from the reference level. Change to level. Specifically, the opening degree of the supply valve 65 of the air suspension 51a is reduced to reduce the amount of air in the air spring 53, and the opening degree of the supply valve 65 of the air suspension 51b is increased to increase the amount of air in the air spring 53. Control to increase.

In step S29, the control device 70 changes the vehicle height of the left front wheel 91L from the reference level to a high level while maintaining the vehicle height of the rear wheels 92 at the reference level, and lowers the vehicle height of the right front wheel 91R from the reference level. Change to level. Specifically, the opening degree of the supply valve 65 of the air suspension 51a is increased to increase the amount of air in the air spring 53, and the opening degree of the supply valve 65 of the air suspension 51b is decreased to increase the amount of air in the air spring 53. Control to reduce.

In this way, when the vehicle 9 turns to the left or right, the air suspensions 51a and 51b of the front wheels 91 are controlled so that the vehicle height on the inner wheel side of the turn is higher than the vehicle height on the outer circumference side of the turn. That is, the vehicle height of the wheel (one of the pair of front wheels 91) equipped with the in-wheel motor driving device 1 that is regenerated during turning is the wheel (a pair) equipped with the in-wheel motor driving device 1 that is power-driven. It is adjusted to be higher than the vehicle height of the front wheel 91). As a result, the inclination of the vehicle body 90 in the left-right direction as shown in FIG. 18 can be suppressed.

In the present embodiment, the vehicle height of the rear wheels 92 is not changed when the vehicle 9 turns (in steps S28 and S29), but the vehicle height of the rear wheels 92 is not limited, and the vehicle height of the rear wheels 92 is the front wheels 91. It may be between the height of one vehicle and the height of the other of the front wheels 91.

As described above, by changing the vehicle height of the wheels 91 in the front-rear direction or in the left-right direction according to the traveling state of the vehicle 9, it is possible to suppress or prevent the posture disorder of the vehicle body 90. .. In particular, when the vehicle 9 turns, the left and right vehicle heights are positively different, so that the roll peculiar to the in-wheel motor vehicle 9 can be effectively prevented. Therefore, the vehicle 9 can be prevented from rolling over.

By the way, the compressor 64 (and the motor 63) of the air suspension 51 is typically provided for each air suspension 51 as shown in FIG. 11 (A). As shown in FIG. 11B, a compressor 64 common to the air suspensions 51a and 51b of the front wheels 91L and 91R and a compressor 64 common to the air suspensions 51c and 51d of the rear wheels 92L and 92R are provided. You may. In this case, the compressor 64 and the supply valves 65 of the left and right air suspensions 51a, 51b (or 51c, 51d) are connected by the pressure pipe 64K. Alternatively, as shown in FIG. 11C, only one compressor 64 common to all of the air suspensions 51a to 51c may be provided.

Further, in the form in which the in-wheel motor drive device 1 is provided with a park lock mechanism (not shown), the compressor 64 may also serve as a compressor for operating the park lock. Alternatively, the compressor 64 may also serve as a compressor for operating the brake.

(Modification example)
In the present embodiment, the air suspension 51 is a MacPherson strut type suspension, but the suspension is not limited. For example, as shown in FIGS. 12 and 13, the air suspension 51A may be a double wishbone suspension. In this case, the air suspension 51A includes the upper arm 56 in addition to the damper 52, the air spring 53, the lower arm 54, and the tie rod 55.

Further, the type of the air suspension of the front wheels 91 and the type of the air suspension of the rear wheels 92 may be different.

Further, in the present embodiment, the in-wheel motor vehicle 9 is a four-wheel drive vehicle, but a front-wheel drive vehicle in which the in-wheel motor drive device 1 is mounted only on the front wheels 91 may be used. In this case, the control device as the suspension control means may perform the same control as the control for the suspensions 51a and 51b on the front wheel 91 side of the four-wheel drive vehicle. On the contrary, in the case of a rear-wheel drive vehicle in which the in-wheel motor drive device 1 is mounted only on the rear wheels 92, the control device as the suspension control means is relative to the suspensions 51c and 51d on the rear wheel 92 side of the four-wheel drive vehicle. The same control as the control may be performed.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 in-wheel motor drive, 7 suspension system, 9 in-wheel motor vehicle, 11 wheel hub bearing, 21 motor, 31 deceleration, 51, 51a, 51b, 51c, 51d, 51A air suspension, 53 air spring, 70 Control device, 71 running condition detector, 90 car body, 91,92 wheels.

Claims (9)

The motor unit that drives the wheels, the wheel hub bearing unit that is attached to the wheels, and the rotation of the motor unit are decelerated to the at least a pair of wheels arranged so as to face each other along the vehicle width direction. A suspension system for in-wheel motor vehicles equipped with an in-wheel motor drive that includes a deceleration unit that transmits to the wheel hub bearings.
An air suspension provided between each in-wheel motor drive device and the vehicle body,
A suspension system for an in-wheel motor vehicle, comprising a suspension control means that controls the air suspension to change at least one of a spring constant and a vehicle height when the in-wheel motor drive device runs or regenerates. The in-wheel motor drive device is mounted on at least the front wheels.
Further equipped with a detection means for detecting the running state of the vehicle,
The suspension for an in-wheel motor vehicle according to claim 1, wherein the suspension control means raises the spring constant of the air suspension arranged on the front wheels to be higher than the reference level when turning is detected by the detection means. system. The suspension control means sets the spring setting of the air suspension arranged on the front wheels higher than the reference level when the detection means detects straight movement and the in-wheel motor drive device runs or regenerates. , The suspension system for an in-wheel motor vehicle according to claim 2. The in-wheel motor drive device is also mounted on the rear wheels.
The in-wheel motor vehicle according to claim 2 or 3, wherein the suspension control means maintains the spring constant of the air suspension arranged on the rear wheels at the reference level when the turning is detected by the detection means. Suspension system for. The suspension control means is based on the spring constants of the air suspensions arranged on both the front wheels and the rear wheels when the detection means detects straight movement and the in-wheel motor drive device is driven or regenerated. The suspension system for an in-wheel motor vehicle according to claim 4, which is higher than the level. The in-wheel motor drive device is mounted on at least the front wheels.
Further equipped with a detection means for detecting the running state of the vehicle,
The suspension control means according to claim 1, wherein when the turning is detected by the detecting means, the vehicle height of the air suspension on the turning inner ring side is made higher than the vehicle height of the air suspension on the turning outer ring side. Suspension system for in-wheel motor vehicles. The suspension control means raises the vehicle height of the air suspension arranged on the front wheels to a reference level when the straight movement is detected by the detection means and the in-wheel motor drive device is driven, and the detection is performed. The in-wheel motor according to claim 6, wherein when the in-wheel motor drive device is regenerated while the straight running is detected by the means, the vehicle height of the air suspension arranged on the front wheels is lowered below the reference level. Suspension system for vehicles. The in-wheel motor drive device is also mounted on the rear wheels.
The in-wheel motor vehicle according to claim 6 or 7, wherein the suspension control means maintains the vehicle height of the air suspension arranged on the rear wheels at a reference level when turning is detected by the detection means. Suspension system for. The suspension control means sets the vehicle height of the air suspension arranged on the front wheels to the air arranged on the rear wheels when the detection means detects that the vehicle travels straight and the in-wheel motor drive device drives the vehicle. When the height of the suspension is higher than the vehicle height, the straight movement is detected by the detection means, and the in-wheel motor drive device regenerates, the vehicle height of the air suspension arranged on the front wheels is arranged on the rear wheels. The suspension system for an in-wheel motor vehicle according to claim 8, wherein the height of the air suspension is lower than the vehicle height.

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