JP4736402B2 - Motor built-in suspension device and electric vehicle equipped with the same - Google Patents

Description

  The present invention belongs to a technical field of a motor built-in suspension device that actively changes a suspension stroke of a vehicle and an electric vehicle including the same.

As active suspension technology, the ride comfort of passengers is enhanced by adjusting the hydraulic pressure supplied to the hydraulic cylinders in the suspension provided between the vehicle body and wheels according to the sensor signals from the acceleration sensor, vehicle height sensor, etc. At the same time, one that improves the rough road running performance is known (see, for example, Non-Patent Document 1).
"Automotive suspension": Kayaba Industry Co., Ltd. (Sankaido)

  However, the conventional technology requires a hydraulic pressure generator, a hydraulic circuit, and the like, and the structure of the vehicle is complicated. In addition, there is a problem that it is difficult to improve the traveling efficiency of the vehicle because of an increase in vehicle weight and energy consumption.

  The present invention has been made paying attention to the problems of the above-described conventional technology, and its object is to provide a motor-integrated suspension device having a simple structure and excellent energy efficiency, and an electric vehicle equipped with the same. It is to provide.

In order to achieve the above object, in the present invention,
A suspension mechanism that connects the vehicle body and a rotation support unit that rotatably supports the wheel, and attenuates the vertical movement of the vehicle body;
A motor for generating a driving force on the wheels;
A swinging member for swinging the motor around the rotation axis of a wheel with respect to the rotation support unit;
And connecting the body and the swing member, a coupling member for lowering the vehicle body in response to the swinging direction of the motor,
It is characterized by providing.

  Therefore, in the present invention, since the vehicle height can be adjusted by the torque reaction force of the motor, there is no need to mount an actuator on the vehicle for the active suspension, the vehicle can be configured simply, and the active suspension is excellent in energy efficiency. The same effect can be obtained.

  Hereinafter, the best mode for carrying out an electric vehicle of the present invention will be described based on Examples 1 to 3 shown in the drawings.

First, the configuration will be described.
[System overall configuration]
FIG. 1 is an overall system diagram illustrating the electric vehicle according to the first embodiment. As shown in FIG. 1, the electric vehicle according to the first embodiment includes electric motors 3RL and 3RR as driving force generation sources, and the rotation shafts of the electric motors 3RL and 3RR are connected to speed reducers 4RL and 4RR. Thus, the electric vehicle is connected to the rear wheels 2RL and 2RR. Here, the output characteristics of the two electric motors 3RL and 3RR, the reduction ratios of the two reduction gears 4RL and 4RR, and the radii of the two left and right rear wheels 2RL and 2RR are all the same.

  Each of the electric motors 3RL and 3RR is a three-phase synchronous motor in which a permanent magnet is embedded in a rotor. A torque command value tTRL (left) is received by the drive circuits 5RL and 5RR that control power transfer to and from the lithium ion battery 6 from the integrated controller (motor torque control means) 30 with the power running and regenerative torque of the electric motors 3RL and 3RR. Rear wheel) and tTRR (right rear wheel) are adjusted to match each other. Then, the drive circuits 5RL and 5RR transmit the motor rotation speed detected by a rotation position sensor (not shown) attached to each motor rotation shaft to the integrated controller 30, respectively.

  The front wheel 42 is provided on the turning rotation shaft 41 of the front wheel 42, and details are shown in FIG. 2. The turning rotation shaft 41 of the front wheel 42 is inside the hollow support portion 45 of the front wheel 42 and rotates with respect to the hollow support portion 45 via a bearing. The elements 44 and 43 and the front wheel 42 are all supported so as to rotate integrally around the turning shaft 41. Here, the intersection point P with the ground surface when the center of the rotation shaft 41 is extended and the point Q directly below the rotation center point 43 of the tire are configured such that the distance is ζ (> 0). A so-called caster structure in which the tire naturally steers so that the traveling direction of the turning rotation shaft 41 of the front wheel 42 coincides with the tire orientation A by traveling resistance during traveling is employed. The hollow support portion 45 of the front wheel 42 has a support shaft (not shown) in the vehicle longitudinal direction and the vehicle lateral direction so that the hollow support portion 45 is not easily deformed in the vehicle longitudinal and lateral directions. Further, the hollow support portion 45 is provided with a spring and a damper (not shown) with respect to the vertical direction, making it difficult to transmit the vertical force received by the front wheel 42 from the road surface to the vehicle body.

  Further, the front wheel 42 is provided with a friction brake by a hydraulic system (not shown) at a part 44, and the hydraulic pressure of the brake system increases according to the depression of the brake pedal 22 by the driver, and the part 44 according to the increase of the hydraulic pressure. The brake pad fixed to the front wheel 42 brakes the front wheel 42 by sandwiching a disk that rotates together with the front wheel 42. The rear wheels 2RL and 2RR are also provided with friction brakes (not shown), and, like the front wheels 42, the rear wheels 2RL and 2RR are braked in response to depression of the brake pedal 22 by the driver.

[Configuration of motor built-in suspension device]
Next, the motor built-in suspension device of the first embodiment mounted on the rear wheels 2RL and 2RR will be described. 3A is a view of the right rear wheel 2RR as viewed from the front of the vehicle, and FIG. 3B is a view of the right rear wheel 2RR as viewed from the inside of the vehicle. Since the left rear wheel 2RL has the same shape as the right rear wheel 2RR, only the configuration of the right rear wheel 2R R will be described, and the description of the left rear wheel 2R L will be omitted.

  The wheels 63 are connected to a brake disc 66 (brake pads are not shown) and a rotating shaft 75, which rotate at the same speed. The rotary shaft 75 is rotatably supported by a hub (rotation support portion) 64 via a bearing (not shown). The hub 64 is connected to the vehicle body via the underarm 65, and further connected to the vehicle body via the member 72, the spring 61, and the damper 62. The spring 61, the damper 62, and the under arm 65 constitute a suspension mechanism that attenuates the vertical movement of the vehicle body.

  The rotating shaft 75 is connected to a gear 71, and the gear meshes with the output shaft of an electric motor (hereinafter referred to as motor) 70 at a fixed gear ratio. Further, the rotation shaft 75 passes through the rotation support member 69 and is supported via a bearing, and the rotation support member 69 is supported by the links 73 and 74. The case of the motor 70 and the case of the gear 71 are integrally formed and rotate around the rotation shaft 75. The upper part of the case of the motor 70 is connected to the vehicle body via a damper (coupling member) 68 and a spring 67.

  That is, the motor 70 is provided on the lower spring side of the suspension mechanism (the spring 61 and the damper 62) so as to be swingable around the rotation shaft 75 of the wheel 63 with respect to the hub 64, and rotates the wheel 63 in the forward direction. When the motor 70 is driven, the motor 70 itself is set to swing around the rotation shaft 75 upward (clockwise in FIG. 3B). On the other hand, when the motor 70 is driven so as to rotate the wheel 63 in the reverse direction, the motor 70 swings around the rotation shaft 75 downward (counterclockwise).

  In the electric vehicle shown in FIG. 1, electric motors 3RL, 3RR, a battery, and the like are arranged in front and rear positions of the rear wheels 2RL and 2RR so that the front and rear center-of-gravity positions are closer to the rear wheels. For example, the front / rear center of gravity position is designed so that the ratio of the front wheel load to the sum of the rear left and right wheels is 2: 8.

Next, the integrated controller 30 will be described.
The integrated controller 30 includes an accelerator opening signal detected by the accelerator pedal sensor 23, a brake pedaling force signal detected by the brake pedal sensor 22, and a steering wheel detected by a steering angle sensor 21 attached to the rotation shaft of the steering wheel 11. 11, a state signal of the shift lever 25 operated by the driver, a front wheel rotation speed signal detected by a front wheel rotation sensor 49 attached to the turning shaft 43 of the front wheel 42, and drive circuits 5 RL and 5 RR. The rotational speeds of the rear wheel motors 3RL and 3RR received from the above are input. The shift position of the shift lever 25 includes a position “P” that can be selected only when the vehicle is stopped and is used during parking, and a position “D” that is used during normal forward travel.

  Based on these signals, the integrated controller 30 calculates a torque command value tTRL for the rear left wheel motor 3RL and a torque command value tTRR for the rear right wheel motor 3RR, and transmits them to the drive circuits 5RL and 5RR of the motors 3RL and 3RR. To do. Here, the torque command value tTRL to the rear left wheel motor 3RL and the torque command value tTRR to the rear right wheel motor 3RR are both in units of Nm, and the direction in which the vehicle is accelerated forward is positive.

Next, the operation will be described.
[Vehicle height adjustment according to motor torque]
In FIG. 3B, when the motor 70 is driven so as to rotate the wheel 63 in the forward direction (clockwise in the figure), the motor 70 moves upward (clockwise in the figure) by the reaction torque of the motor 70. Swing. Thereby, the damper 68 provided integrally with the motor 70 moves upward. On the other hand, when the motor 70 is driven to rotate the wheel 63 in the reverse direction (clockwise in the figure), the motor 70 swings downward (counterclockwise in the figure) by the reaction torque of the motor 70. Thereby, the damper 68 moves downward.

  That is, when torque is generated in the direction in which the motor 70 drives the vehicle (forward direction), the motor 70 transmits the driving torque to the rotating shaft 75 via the gear 71 and the vehicle body is pushed upward by the reaction force. It is done. On the contrary, when the motor 70 generates torque in the direction of braking the vehicle (reverse direction), the motor 70 transmits the braking torque to the rotating shaft 75 via the gear 71 and the reaction force causes the vehicle body to face downward. Pushed down.

  The push-up amount and the push-down amount of the vehicle body increase in proportion to the motor torque, that is, the current value supplied to the motor 70. By changing the characteristics of the damper 68 and the spring 67 (spring constant, damping coefficient, etc.), the motor The vertical movement amount of the vehicle body relative to the torque can be set to a desired characteristic according to the vehicle.

[Mode selection control processing]
FIG. 4 is a flowchart showing the flow of the mode selection control process executed by the integrated controller 30 according to the first embodiment. Each step will be described below. The integrated controller 30 includes peripheral components such as a RAM / ROM in addition to the microcomputer, and executes the flowchart of FIG. 4 at regular intervals, for example, every 5 ms.

  In step S401, each sensor signal and reception signals from the drive circuits 5RL and 5RR are stored in a RAM variable, and the process proceeds to step S402. Specifically, the accelerator opening signal is stored in a variable APS (unit is% and fully opened is 100%), the brake pedal force signal is stored in a variable BRK (unit is Pa), and the steering wheel 11 The rotation angle signal is stored in a variable δ (unit is rad, counterclockwise is positive), and the shift lever signal is stored in a variable SFT. Further, the rotational speed signal from the front wheel rotation sensor 49 is stored in a variable NFL (unit is rad / s, and the direction in which the vehicle moves forward is positive). Further, for the signals received from the drive circuits 5RL and 5RR, the rotational speeds of the respective motors are stored in the variables NRL and NRR (both units are rad / s, and the direction in which the vehicle advances is positive).

In step S402, the speed V of the vehicle (unit is m / s, the forward direction of the vehicle is positive) is calculated by the following equation, and the process proceeds to step S403.
V = (NFL * Rf + NRL / GG * Rr + NRR / GG * Rr) / 3
Here, Rf is the radius of the front wheel, Rr is the radius of the rear wheel, and GG is the reduction ratio of the reduction gear of the rear wheel.

  In step S403, it is determined whether or not the shift lever position is the position “P” used during parking. If “P”, the process proceeds to step S404, and this routine is terminated with tTRL = tTRR = 0. If not, the process proceeds to step S405, a calculation routine in mode D described later is executed, and this routine is terminated.

[About the design principle and operation form of the controller that realizes the reference model response]
Next, a method for calculating the torque command value tTRL for the rear left wheel motor 3RL and the torque command value tTRR for the rear right wheel motor 3RR in the calculation routine (FIG. 5) in mode D of step S405 will be described. Before describing the calculation process, the calculation principle and method of motor torque command value in mode D will be described.

“Motor motion and control” (Sankaido) shows the equation of motion of the vehicle behavior for steering the front and rear wheels. For example, for p194, the front wheel rudder angle δf [rad] and the rear wheel rudder angle δr [rad] are the manipulated variables, and the vehicle yaw rate γ [rad / s] and the vehicle slip angle β [rad] at the vehicle body center of gravity are the state variables. The equation of motion is shown. This equation of motion shows that the vehicle speed V [m / s] is constant (dV = 0), V ≠ 0, and the slip angle (β [rad]) is very small (| β | << 1, sinβ ≒ β, cosβ ≒ 1) Derived on the premise of.
The concept of the equation of motion can be applied to the electric vehicle according to the first embodiment of the present invention. That is, the operation amount of the right wheel driving force u [N] and the left wheel driving force −u [N] is added, and the front wheel has the caster type shown in FIG. Assuming that the force is almost zero, the equation of motion can be derived as follows.

  Here, Lr is the distance [m] between the rear wheel shaft and the center of gravity, Lt is the tread base distance / 2 [m] of the rear wheel, m is the vehicle weight [kg], and Iγ is the yaw moment of inertia [Nmss]. Kr is the rear wheel tire cornering stiffness [N / rad], which takes into account the decrease in cornering power with respect to the steering angle due to the influence of the rear wheel steering stiffness. V is the vehicle speed [m / s], γ is the yaw rate [rad / s], and β is the vehicle slip angle [rad] at the center of gravity of the vehicle.

This equation of motion can be rewritten into the following form using the differential operator s.
β = {Q13 (s) / Qden (s)} · u
γ = {Q23 (s) / Qden (s)} · u (A3)
Q13 (s), Q23 (s), and Qden (s) are all functions of the vehicle speed V and are expressed by the following equations.
Q ₁₃ (s) ＝ − 2Lt (mV ² −2LrKr)
Q ₂₃ (s) = 2VLt (mVs + 2Kr)
Qden (s) = mV ² I _γ s ² +2 VKr (mLr ² + I _γ ) s +2 mV ² LrKr (A4)

  In the first embodiment, the controller p1 (calculating the command value u * of the driving force difference between the left and right wheels from the steering operation amount δ so that the response of the yaw rate γ to the steering operation amount δ becomes a desirable transfer characteristic (reference model). s) can be derived as follows.

Now, a desirable transfer characteristic (normative model) of the yaw rate γ with respect to the steering operation amount δ is set as G _γδ , for example, as follows.
G _γδ = m2 / (s ² + 2wns + wn ² )… (A5)

That is, the desired response of the yaw rate γ to the steering operation amount δ is set to a smooth secondary response characteristic (for example, wn = 4π, m ₂ = wn2 / 4). On the other hand, the relationship between the steering operation amount δ and the yaw rate γ is as follows.
γ = ({Q23 (s) / Qden (s)} p1 (s) δ (A6)

Therefore, the equation (A7) is derived from the condition that this transfer characteristic matches the desired transfer characteristic G _γδ ,
_{G γδ = m 2 / (s} 2 + 2wns + wn 2) = {Q23 (s) / Qden (s)} p1 (s) ... (A7)
By solving this simultaneous equation using the relational expression of equation (A4), the controller p1 (s) can be derived as in equation (A8).
p1 (s) = (m ₂ / 2Lt) {mVI _γ s ² + 2Kr (mLr ² + I _γ ) s + 2mVLrKr} / {(mVs + 2Kr) (s ² + 2wns + wn ² )}
… (A8)

As described above, in the first embodiment, the controller p1 (s ⁾ that calculates the command value u ^* of the driving force difference between the left and right wheels so that the response of the yaw rate γ to the steering operation amount δ becomes a desirable transfer characteristic (reference model). ).

Next, a method for realizing the controller p1 (s) of the formula (A8) will be described. Since p1 (s) can be rewritten by the following equation (A9), a method for realizing equation (A9) will be described. b0, b1, and b2 are functions such as the vehicle speed V. yx = (b2s ² + b1s + b0) / (s ³ + a2s ² + a1s + a0) ux (A9)

  Here, equation (A9) can be rewritten as shown in FIG. Therefore, at predetermined time intervals (for example, every 5 ms), first, a2, a1, a0, b0, b1, b2 in FIG. 6 are sequentially updated according to the vehicle speed V, and the integration calculation is performed by Euler approximation, for example. After updating X3, X2, and X1, the output yx is finally calculated from X3, X2, X1, b0, b1, and b2 every moment.

[Calculation routine in mode D]
In the calculation routine in the mode D of step S405 in FIG. 4, the flowchart in FIG. 5 is executed.

  In step S501, the target driving force (driving force target value) tTD of the vehicle is calculated (corresponding to driving force target value generating means). The calculation is performed by referring to a map MAP_tTD (V, APS) stored in advance in the ROM. The map MAP_tTD (V, APS) is characteristic data with the vehicle speed V and the accelerator opening APS as axes, and is set as shown in FIG. 7, for example.

  In steps S502 to S504, the target torque tU [Nm] of the driving force difference generated in the rear wheel left and right motors is calculated according to the steering wheel rotation angle δ and the vehicle speed V. Based on the above design principle, the calculation is performed so that the response of the yaw rate γ to the steering operation amount δ is a desirable transfer characteristic (the normative model shown in Expression (A5)).

In step S502, using the vehicle speed V calculated in step S402, the values corresponding to a0, a1, and a2 in equation (A9) are calculated as follows for equation (A8).
a2 = 2 (Kr / m / V + wn)
a1 = wn (4Kr / m / V + wn)
a0 = 2Krwn ² / m / V… (B0)
Vehicle design values are used for m and Kr. Further, the value of the vehicle speed V is calculated by limiting the minimum value to a small value (for example, 0.01) so that 0% does not occur in the calculation.

In step S503, using the vehicle speed V calculated in step S402, the values corresponding to b0, b1, and b2 in equation (A9) are calculated as follows for equation (A8). b2 ＝ {m ₂ / (2Lt)} ・ Ir
b1 = {m ₂ / Lt} · Kr (mLr ² + Ir) / m / V
b0 = {m ₂ / Lt} · LrKr (B1)
Here, m ₂ is such that the steady value of the yaw rate with respect to the steering wheel rotation angle δ is, for example, δ / 4.
m ^₂ = wn _2/4
Keep it as Vehicle design values are used for m, Ir, Lr, and Lt.

  In step S504, X3, X2, and X1 obtained by executing step S504 in the previous time are used, and X3, X2, and X1 are updated by Euler approximation of the integral calculation in FIG. In FIG. 6, ux is the steering wheel rotation angle δ, and the output yx corresponds to the variable tU of the target left / right driving force difference. After updating X3, X2, and X1, the output yx is calculated from the relational expression shown in FIG. 6 according to those values and b0, b1, and b2 obtained in step S503, and substituted for tU.

In step S505, torque command values tTRL and tTRR for the rear wheels are calculated from the target driving force tTD and the target left / right driving force difference tU by the following equation (corresponding to torque command value generating means).
tTRL = tTD * Rr / GG / 2−tU * Rr / GG
tTRR ＝ tTD * Rr / GG / 2 ＋ tU * Rr / GG… (B3)

In step S506, advance compensation is performed by performing filtering processing of the next transfer characteristic W1 (s) on the torque command value obtained in step S505 (corresponding to advance compensation means).
W1 (s) = (τ ₂ s +1) / (τ ₁ s +1)
Here, τ ₂ <τ ₁ is set as a condition for lead compensation. For example, τ ₁ = 0.05 and τ ₂ = 0.1.
Then, after the calculation in step S506, this routine ends.

[Problems of conventional active suspension]
As a technology for actively changing the suspension stroke of a vehicle, there is an active suspension technology. Section 8.3 of “Automobile Suspension” (Edited by Kayaba Kogyo Co., Ltd .: Sankaido) shows a plurality of application examples.

  The hydraulic active suspension technology shown here has a hydraulic cylinder in the suspension located between the vehicle body and the wheel, and adjusts the supply pressure from the hydraulic source on the vehicle side by a control valve, It adjusts the hydraulic pressure and changes the characteristics of the suspension. Anti-roll control (control to reduce the roll during turning) and anti-dive control by adjusting the hydraulic pressure in the hydraulic cylinder according to the signals of various sensors (acceleration sensor, height sensor, etc.) provided in the vehicle (Control to reduce nose dive during braking), bouncing control (control to reduce vehicle body shake due to road surface input), vehicle height adjustment function, etc., enhancing ride comfort for passengers and improving bad road running Realized.

  However, the above-described conventional active suspension requires a hydraulic pressure generating device, a hydraulic circuit, etc. as an energy generation source and energy transmission circuit for the active suspension, and the manufacturing cost increases due to the complicated structure of the vehicle. There is a problem that it is difficult to improve the running efficiency of the vehicle because of an increase in vehicle weight and energy consumption.

[Active suspension action using motor reaction force]
On the other hand, the electric vehicle according to the first embodiment includes a motor-integrated suspension in the rear wheels 2RL and 2RR, and when the left and right motors 3RL and 3RR drive the vehicle, the vehicle is lifted by a motor reaction force. As a result, when the vehicle is accelerated, the motor torque acts in a direction to push down the rear wheels 2RL and 2RR, so that the inertia of the left and right motors 3RL and 3RR increases the wheel load of the rear wheels 2RL and 2RR, thereby improving the traction performance. It has been realized.

  Also, the torques of the left and right motors 3RL and 3RR are adjusted so that the driving force of the outer ring is greater than the driving force of the inner ring during turning (p1 (0)> 0 in equation (A8)). The driving force of the right outer ring increases during rotation). Therefore, the force that lifts the vehicle by the driving force of the outer ring becomes larger than the force that lifts the vehicle by the driving force of the inner ring, and the roll motion of the vehicle can be suppressed. Depending on the design parameters of the motor built-in suspension device, a reverse roll can be realized.

  Further, since driving force is generated by the rear wheels 2RL and 2RR during acceleration driving (formula (B3)), the rear end of the vehicle is lifted by the motor reaction force, and the squat operation of the vehicle can be suppressed. Depending on the design parameters, a dive operation can be realized.

  Furthermore, during deceleration braking such as when the brake is depressed or the accelerator is off, regenerative braking force is generated by the rear wheels 2RL and 2RR (see the characteristics and equation (B3) in FIG. 7), so the rear end of the vehicle is pushed down by the motor reaction force, The dive operation of the vehicle can be suppressed. Again, depending on the design parameters, a squat operation can be achieved.

  In the first embodiment, advance compensation is performed when torque is commanded to the motors 3RL and 3RR (step S506). When changing the torque of the motors 3RL, 3RR, the position of the motors 3RL, 3RR changes up and down by the motor reaction force, so there is a problem that the energy is not transmitted as the driving force. Therefore, the target driving force tTD set with higher accuracy can be realized.

  As described above, in the electric vehicle according to the first embodiment, it is possible to suppress the roll and the pitch separately from the suspension characteristics due to the spring constant and the damping coefficient of the suspension. Therefore, for example, it is possible to suppress rolls and pitches while softening suspension characteristics during constant speed running.

Next, the effect will be described.
In the electric vehicle according to the first embodiment, the following effects can be obtained.

  (1) Suspension mechanism (spring 61, damper 62, underarm 65) that attenuates the vertical movement of the vehicle body by connecting the vehicle body and the hub 64 that rotatably supports the rear wheels 2RL, 2RR, and the rear wheels 2RL, 2RR Motors 3RL and 3RR that generate a driving force on the motor, and a damper 68 that couples the motors 3RL and 3RR and the vehicle body so that a motor reaction force that moves the vehicle body up and down according to the direction in which the motor torque is generated acts on the vehicle body. Therefore, it is not necessary to mount an actuator for the active suspension, and the vehicle can be configured simply. Furthermore, it is excellent in energy efficiency and the same effect as the active suspension can be obtained.

  (2) The motors 3RL and 3RR are provided on the unsprung side of the suspension mechanism so as to be swingable around the rotation shaft 75 of the rear wheels 2RL and 2RR with respect to the hub 64 so that the rear wheels 2RL and 2RR are rotated in the forward direction. When the motors 3RL and 3RR are driven, the motor itself swings around the rotating shaft 75 and the damper 68 pushes up the vehicle body, so that the motor torque is increased when the vehicle is accelerated. It acts in the direction of pushing down 2RR, and the wheel load of the rear wheels 2RL and 2RR can be increased by the inertia of the motors 3RL and 3RR, thereby improving the traction performance.

  (3) Since the suspension device built in the motor is used as the suspension device that connects the left and right rear wheels 2RL and 2RR of the vehicle and the vehicle body, roll operation and pitch operation are performed separately from the suspension characteristics due to the spring constant and damping coefficient of the suspension mechanism. It can be controlled according to the motor torque.

  (4) Since the integrated controller 30 that controls the motor torque of the left and right motors 3RL and 3RR according to the running state of the vehicle is provided, the roll operation and pitch of the vehicle body suitable for the running state during acceleration driving and deceleration braking of the vehicle Operation can be realized.

  (5) Since the integrated controller 30 increases the motor torque on the outer turning wheel side when turning the vehicle, the motor torque on the turning inner wheel side can be suppressed, so that the roll motion of the vehicle during turning can be suppressed and the ride comfort is deteriorated. Can be prevented.

  (6) Since the rear wheels 2RL and 2RR equipped with the motor built-in suspension device are arranged on the rear side of the front / rear center of gravity position of the vehicle, the vehicle height at the rear end side of the vehicle at the time of acceleration driving and deceleration braking can be freely set. Can be adjusted.

  (7) Since the integrated controller 30 drives the left and right motors 3RL and 3RR during acceleration driving of the vehicle, the rear end of the vehicle is lifted, and the squat operation of the vehicle accompanying the backward movement of the center of gravity during acceleration driving can be suppressed. it can.

  (8) The integrated controller 30 regenerates the left and right motors 3RL and 3RR during deceleration braking of the vehicle, so that the rear end of the vehicle is pushed down to suppress the dive operation of the vehicle accompanying the forward movement of the center of gravity during deceleration braking. it can.

  (9) Driving force target value generating means (step S501) for generating a target driving force tTD of the vehicle, torque command value generating means (step S505) for generating torque command values tTRL and tTRR corresponding to the target driving force tTD, And torque compensation means (step S506) for performing advance compensation with respect to the torque command values tTRL and tTRR, the amount of energy that is not transmitted to the rear wheels 2RL and 2RR as the driving force is compensated by advance compensation. By doing so, the target driving force tTD can be realized with high accuracy.

First, the configuration will be described.
FIG. 8 is a configuration diagram of an electric vehicle in which the four wheels according to the second embodiment are driven by separate electric motors. The same parts as those of the first embodiment shown in FIG.

  The electric vehicle according to the second embodiment includes electric motors 3FL, 3FR, 3RL, and 3RR as driving force generation sources. The rotation shafts of the respective motors are electrically driven via the speed reducers 4FL, 4FR, 4RL, and 4RR. It is connected to left and right front wheels 2FL and 2FR and left and right rear wheels 2RL and 2RR of the vehicle. The output characteristics of the four motors 3FL, 3FR, 3RL, 3RR, the reduction ratios of the four reduction gears, and the radii of the four wheels are all set to be the same. The motors 3FL, 3FR, 3RL, 3RR and the speed reducers 4FL, 4FR, 4RL, 4RR are incorporated in the suspension shown in FIGS. 3 (a) and 3 (b). Here, it is assumed that the spring characteristics and damper characteristics of the suspension are all the same.

  Each of the motors 3FL, 3FR, 3RL, and 3RR is a three-phase synchronous motor in which a permanent magnet is embedded in a rotor. Torque command values tTFL (front left wheel), tTFR (front right wheel) that drive circuits 5FL, 5FR, 5RL, and 5RR that control power exchange with the lithium ion battery 6 receive the power running and regenerative torque of those motors from the integrated controller 30 ), TTRL (left rear wheel), and tTRR (right rear wheel).

  The front wheels 2FL and 2FR are mechanically steered via the steering gear 14 by the rotational movement of the steering wheel 11 operated by the driver.

The integrated controller 30 includes an accelerator opening signal detected by the accelerator pedal sensor 23, a brake pedaling force signal detected by the brake pedal sensor 22, and a steering angle sensor 21 attached to the rotating shaft of the steer wheel 11. A rotation angle signal of the link wheel 11 is input. Based on these signals, the integrated controller 30 calculates torque command values tTFL, tTFR, tTRL, tTRR for each motor and transmits them to the drive circuits 5FL, 5FR, 5RL, 5RR of the motors 3FL, 3FR, 3RL, 3RR. To do. Further, an acceleration sensor (not shown) for detecting vertical acceleration is provided on the suspension vehicle body side of each wheel, and each acceleration signal is also input to the integrated controller 30.
Note that the battery 6 and the motors 3FL, 3FR, 3RL, 3RR are arranged so that the front-rear center of gravity of the electric vehicle according to the second embodiment is located approximately at the center between the front wheels 2FL, 2FR and the rear wheels 2RL, 2RR. Yes.

  The integrated controller 30 includes peripheral components such as RAM / ROM in addition to the microcomputer, and executes a process of calculating torque command values tTFL, tTFR, tTRL, tTRR to each motor based on each sensor signal. .

Next, the operation will be described.
[Torque command value calculation control processing]
FIG. 9 is a flowchart showing the flow of torque command value calculation control processing executed by the integrated controller 30, and each step will be described below. This control process is executed every certain time, for example, every 5 ms.

  First, in step S901, sensor signals and received signals from the drive circuits 5FL, 5FR, 5RL, and 5RR are stored in RAM variables. Specifically, the accelerator opening signal is stored in the variable APS (unit:%, where 100% is fully opened), the brake pedal force signal is stored in the variable BRK (unit: Pa), and the steering wheel 11 is rotated. The angle signal is stored in the variable STR (unit is rad, counterclockwise is positive). Also, for the signals received from the drive circuits 5FL, 5FR, 5RL, 5RR, the rotation speed of each motor is set to the variable NFL, NFR, NRL, NRR (all units are rad / s, and the direction in which the vehicle moves forward is corrected). ). Also, the vehicle vertical speed at each wheel position is calculated by integrating the signals of the acceleration sensor signals attached to the upper body of each wheel, and stored in the variables VFL, VFR, VRL, and VRR (the downward direction is positive) ).

In step S902, the vehicle speed V (unit is m / s, and the forward direction of the vehicle is positive) is calculated by the following equation.
V = (NFL / GG * R + NFR / GG * R + NRL / GG * R + NRR / GG * R) / 4
Where R is the wheel radius and GG is the reduction gear ratio.

  In step S903, the target driving force tTD of the vehicle is calculated. The calculation is performed by referring to a map MAP_tTD (V, APS) stored in advance in the ROM. The map MAP_tTD (V, APS) is characteristic data with the vehicle speed and the accelerator opening as axes, and is set as shown in FIG.

  In step S904, a target left / right driving force difference tU is calculated. The calculation is performed by referring to the map MAP_tU (V, STR) stored in advance in the ROM. The map MAP_tU (V, STR) is characteristic data with the vehicle speed and the rotation angle signal of the steering wheel 11 as axes. For example, the larger the absolute value of the rotation angle signal STR of the steering wheel 11, the larger the absolute value is set. However, the higher the vehicle speed V, the smaller the absolute value is set. Further, the value is positive when the rotation angle signal STR of the steering wheel 11 is positive (when steering to the left), and negative when STR is negative (when steering to the right). Set to. By adopting such a configuration, it is possible to realize turning assist based on the difference between the left and right driving forces.

In step S905, torque command values tTFL, tTFR, tTRL, tTRR for the four wheels are calculated from the target driving force tTD and the target left / right driving force difference tU by the following equations.
tTFL = tTD * R / GG / 6 − tU * R / GG / 4
tTFR = tTD * R / GG / 6 + tU * R / GG / 4
tTRL = tTD * R / GG / 3 − tU * R / GG / 4
tTRR = tTD * R / GG / 3 + tU * R / GG / 4

In step S906, lead compensation is performed by performing filtering processing of the next transfer characteristic W1 (s) on the torque command values tTFL, tTFR, tTRL, and tTRR obtained in step S905.
W1 (s) = (τ ₂ s +1) / (τ ₁ s +1)
Here, τ ₂ <τ ₁ is set as a condition for lead compensation. For example, τ ₁ = 0.05 and τ ₂ = 0.1.

In step S907, in order to suppress the vertical vibration of the vehicle body due to unevenness disturbance from the road surface, with the obtained torque command value tTFL step S906, tTFR, tTRL, tTRR respect, firstly, each vehicle body vertical speed VFL of the position of each wheel, VFR, VRL, VRR determined Me by a signal a (downward positive) from the acceleration sensor (road surface detecting means), the vehicle body vertical velocity VFL, VFR, VRL, corresponds to the correction is carried out (torque command value correcting means in accordance with the VRR ).
tTFL = tTFL + K1, VFL
tTFR = tTFR + K1 ・ VFR
tTRL ＝ tTRL ＋ K1 ・ VRL
tTRR ＝ tTRR ＋ K1 ・ VRR

  Here, K1 is a positive value.When the vehicle body is moving upward, the motor torque is reduced to generate a downward force on the vehicle body.When the vehicle body is moving downward, the motor torque is increased. Generate upward force on the car body. By performing such control, an effect of suppressing the vertical movement of the vehicle body is realized.

Further, in step S907, the next correction is continuously performed so that the total sum of the driving forces is not changed by the correction of the previous equation.
tTFL = tTFL−K1, (VFL + VFR + VRL + VRR) / 4
tTFR = tTFR−K1 ・ (VFL + VFR + VRL + VRR) / 4
tTRL = tTRL−K1 ・ (VFL + VFR + VRL + VRR) / 4
tTRR = tTRR−K1 ・ (VFL + VFR + VRL + VRR) / 4

  In step S908, torque command values tTFL, tTFR, tTRL, tTRR for the four wheels are transmitted to the drive circuits 5FL, 5FR, 5RL, 5RR for each motor.

[Vertical vibration suppression effect when the road surface changes]
An example of the simulation result is shown in FIG. FIG. 10 is a simulation result of the turning outer wheel when the vehicle shifts to the turning state after one second from the straight traveling state. In a situation where the wheel load increases by about 1000 N from the time 1 second and climbs a step of 3 cm between the time 5 seconds and 6.5 seconds, the electric vehicle (solid line) to which the motor built-in suspension of Example 2 is applied and the conventional vehicle not to be applied The result with (dotted line) is shown. The fourth level represents the vertical displacement of the vehicle body.

  In the conventional vehicle, it can be confirmed that the vehicle body is displaced downward as the wheel load increases. Also, it can be confirmed that the vehicle body is displaced up and down in vibration when climbing the step.

  On the other hand, when the motor built-in suspension device of Example 2 is applied (solid line), it can be confirmed that the vehicle body is displaced upward as the wheel load increases, contrary to the dotted line. That is, a reverse roll is realized in which the vehicle height of the outer wheel is higher than that of the inner wheel when turning. In addition, when climbing up the step, it can be seen that the vertical vibration of the vehicle body is suppressed as compared with the conventional vehicle, and the ride comfort can be improved.

  In the second embodiment, the rear wheels 2RL and 2RR generate a larger driving force than the front wheels 2FL and 2RR during acceleration driving (step S905), so that the rear end of the vehicle is lifted by the motor reaction force and the squat operation of the vehicle is performed. Can be suppressed. Depending on the design parameters of the motor built-in suspension, dive operation can also be realized.

  Further, during deceleration braking with the accelerator off, the rear wheels RL and 2RR generate a regenerative braking force greater than that of the front wheels 2FL and 2RR (step S905). Can be suppressed. Depending on the design parameters of the motor built-in suspension, a squat operation can be realized.

  Also, when there is a vertical change in the road surface, the change is detected as the vertical speed of the vehicle body. When the road surface is convex, the torque command value to the motor is corrected to the braking force side, and when it is concave, it is corrected to the driving force side. (Step S907). Thereby, the vehicle body upper limit movement by the vertical change of a road surface can be suppressed.

  Furthermore, since the motor torque correction due to the vertical change of the road surface is corrected again by another motor (step S907), the target driving force of the vehicle can be realized with high accuracy. Thereby, the drivability of the vehicle by a driver can be raised.

Next, the effect will be described.
In the electric vehicle of the second embodiment, the effects listed below are obtained in addition to the effects (1) to (9) of the first embodiment.

  (10) The front wheels 2FL and 2FR fitted with the motor built-in suspension device are arranged in front of the front / rear center of gravity of the vehicle, and the integrated controller 30 allows the front wheel motor torque to be increased by the front wheel motor torque when the vehicle is driven to accelerate. Since the driving force is distributed between the front and rear wheels so as to be smaller than the vehicle body push-up amount by the motor torque (step S905), the squat operation during acceleration driving can be suppressed.

  (11) At the time of deceleration braking of the vehicle, the integrated controller 30 distributes the regenerative torque of the front and rear wheels so that the amount of pushing down the vehicle body by the front wheel motor torque is smaller than the amount of pushing down the vehicle body by the rear wheel motor torque (step S905). Therefore, the dive operation at the time of deceleration braking can be suppressed.

  (12) Road surface level detecting means for detecting the road surface level and when the detected road surface is convex, the torque command values tTFL, tTFR, tTRL, tTRR to the motors 3FL, 3FR, 3RL, 3RR are set to the braking force side. When the detected road surface is concave, torque command value correction means for correcting the torque command values tTFL, tTFR, tTRL, tTRR to the motors 3FL, 3FR, 3RL, 3RR to the driving force side (step S907) Therefore, the vertical movement of the vehicle body due to the road surface step is suppressed, and deterioration of the ride comfort can be prevented.

  (13) The torque command value correcting means corrects the torque command values tTFL, tTFR, tTRL, tTRR to the motors 3FL, 3FR, 3RL, 3RR to the braking force side when the detected road surface is convex, Torque command values tTFL, tTFR, tTRL, tTRR for each motor 3FL, 3FR, 3RL, 3RR are corrected again to the driving force side, and when the detected road surface is concave, each motor 3FL, 3FR, 3RL, 3RR Torque command values tTFL, tTFR, tTRL, tTRR are corrected to the driving force side, and torque command values tTFL, tTFR, tTRL, tTRR to the motors 3FL, 3FR, 3RL, 3RR are corrected again to the braking force side ( Therefore, the target driving force tTD of the vehicle can be accurately realized while suppressing the vertical movement of the vehicle body due to the road surface step.

First, the configuration will be described.
FIG. 11A is a view of the right rear wheel showing the structure of the motor-integrated suspension device of the third embodiment as seen from the front of the vehicle, and FIG. 11B is a view of the right rear wheel as seen from the inside of the vehicle.

  The wheel 63 is connected to a brake disk 66 (a brake pad is not shown) and a rotary shaft 75 and rotates at the same speed. The rotating shaft 75 is an output shaft of the motor 70 and is rotatably supported by the hub 64 and the member 69 via a bearing. The hub 64 is connected to the vehicle body via the underarm 65, and is connected to the vehicle body via the member 72, the spring 61, and the damper 62. The member 69 is supported by the links 73 and 74. The case of the motor 70 is integrated and rotates around the rotation shaft 75, and the case side surface portion of the motor 70 is connected to the vehicle body via a damper 68 and a spring 67.

Next, the operation will be described.
[Vehicle height adjustment according to motor torque]
In FIG. 11B, when the motor 70 is driven so as to rotate the wheel 63 in the forward direction, the motor 70 transmits a driving torque to 75 and the reaction force pushes the case of the motor 70 upward. . On the contrary, when the motor 70 generates torque in the direction of braking the vehicle, the motor 70 transmits the braking torque to the rotating shaft 75 and the reaction force pushes the case of the motor 70 downward.

  Therefore, in the motor built-in suspension device of the third embodiment, the same effects as the effects (1) and (2) of the first embodiment can be obtained.

(Other examples)
Although the best mode for carrying out the present invention, Examples 1-3 to have been described on the basis that the specific configuration of the present invention, have name limited to the embodiments.

  In the first embodiment, the front wheels are rotating casters, but a so-called steer-by-wire system in which the turning angle can be adjusted with an electric motor is also possible. In that case, the turning angle may be adjusted in the direction in which the wheel position should proceed.

1 is an overall system diagram illustrating an electric vehicle according to a first embodiment. It is the side view and top view which show the front wheel applied to the electric vehicle of Example 1. FIG. It is a figure which shows the structure of the motor built-in suspension apparatus of Example 1. FIG. 3 is a flowchart illustrating a flow of mode selection control processing executed by the integrated controller 30 of the first embodiment. 6 is a flowchart illustrating a calculation routine in mode D according to the first embodiment. It is a figure which shows the calculation method in Example 1. FIG. FIG. 10 is a ROM data characteristic diagram of a target driving force tTD used in a calculation routine in mode D in the first and second embodiments. FIG. 3 is an overall system diagram illustrating an electric vehicle according to a second embodiment. 3 is a flowchart showing a flow of torque command value calculation control processing executed by an integrated controller 30. It is an example of a simulation result of the electric vehicle of Example 1. FIG. It is a figure which shows the structure of the motor built-in suspension apparatus of Example 3. FIG.

Explanation of symbols

2RL, 2RR Rear wheel 3RL, 3RR Electric motor 8 Yaw rate sensor 11 Steering wheel 21 Steering angle sensor 22 Brake pedal sensor 23 Accelerator pedal sensor 24 Acceleration sensor 25 Shift lever 30 Integrated controller 41FL, 41FR Steering rotary shaft 42FL, 42FR Front wheel 45FL, 45FR hollow support member 49 Front wheel rotation sensor

Claims (13)

A suspension mechanism that connects the vehicle body and a rotation support unit that rotatably supports the wheel, and attenuates the vertical movement of the vehicle body;
A motor for generating a driving force on the wheels;
A swinging member for swinging the motor around the rotation axis of a wheel with respect to the rotation support unit;
And connecting the body and the swing member, a coupling member for lowering the vehicle body in response to the swinging direction of the motor,
A motor-embedded suspension device comprising: The motor built-in suspension device according to claim 1,
The motor, swingably provided around the rotation axis of the wheel against the rotational support portion unsprung side of the suspension mechanism,
When the motor is driven so as to rotate the wheel in the forward direction, the motor itself swings upward around the rotation shaft, and the coupling member pushes the vehicle body upward. Motor built-in suspension device. As the suspension system for connecting a wheel and a vehicle body of the left and right sides of the vehicle respectively, an electric vehicle characterized by using a motor built suspension system of claim 1 or claim 2. In the electric vehicle according to claim 3,
Electric vehicle, characterized in that it comprises a motor torque control means for controlling the motor torque of the left and right motors in accordance with the running state of the vehicle. The electric vehicle according to claim 4,
The motor torque control means makes the motor torque of the motor on the side of the turning outer wheel larger than the motor torque of the motor on the side of the turning inner wheel when the vehicle turns. In the electric vehicle according to claim 4 or 5 ,
The motor torque control means includes
Driving force target value generating means for generating a driving force target value of the vehicle;
Torque command value generating means for generating a torque command value corresponding to the driving force target value;
Advance compensation means for performing advance compensation on the torque command value;
An electric vehicle comprising: The electric vehicle according to any one of claims 4 to 6,
The road surface detection means for detecting a road level difference of each wheel position respectively provided,
When the road surface detected at a predetermined wheel position is convex, the motor torque control unit corrects the torque command value to the motor corresponding to the wheel position to the braking force side, and is detected at the predetermined wheel position . An electric vehicle comprising torque command value correction means for correcting a torque command value to a motor corresponding to the wheel position to a driving force side when the road surface is concave. The electric vehicle according to claim 7,
When the road surface detected at a predetermined wheel position is convex, the torque command value correction means corrects the torque command value to the motor corresponding to the wheel position to the braking force side and at least one other motor Correct the torque command value to the driving force side,
When the road surface detected at a predetermined wheel position is concave, the torque command value to the motor corresponding to the wheel position is corrected to the driving force side, and the torque command value to at least one other motor is applied to the braking force. The electric vehicle characterized by correcting to the side. The electric vehicle according to claims 3 to 8,
An electric vehicle characterized in that the wheel on which the motor built-in suspension device is mounted is arranged on the rear side of the front-rear center of gravity position of the vehicle. The electric vehicle according to claim 9,
The motor torque control means, an electric vehicle, wherein during acceleration driving of a vehicle, the driving operation of the left and right motors. In the electric vehicle according to claim 9 or 10,
The motor torque control means, an electric vehicle, wherein the deceleration braking of the vehicle, the left and right motor be regenerative operation. The electric vehicle according to any one of claims 9 to 11,
The wheels equipped with the motor built-in suspension device are respectively arranged on the rear side and the front side of the front and rear center of gravity position of the vehicle,
The motor torque control means distributes the driving force of the front and rear wheels so that the vehicle body push-up amount by the front wheel motor torque is smaller than the vehicle push-up amount by the rear wheel motor torque when the vehicle is accelerated. vehicle. The electric vehicle according to claim 12,
The motor torque control means distributes the regenerative torque of the front and rear wheels so that the amount of depression of the vehicle body by the front wheel motor torque is smaller than the amount of depression of the vehicle body by the rear wheel motor torque during deceleration braking of the vehicle. Electric vehicle.

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