JP2017013627A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle with a brake electric motor for applying a brake force to driving wheels, and capable of reducing longitudinal vibration and noise of the driving wheels generated due to torque ripple at a time of starting a drive electric motor.SOLUTION: An electric vehicle comprises: a drive electric motor that drives driving wheels; and an electromagnetic brake device that brakes the driving wheels, the electromagnetic brake device including a brake electric motor for pressing a frictional member against a rotational body rotating along with the driving wheels. During non-braking (S20), when the drive electric motor rotates at a rotating speed equal to or lower than a reference value (S40), the brake electric motor is actuated in such a manner that a periodic fluctuation of a longitudinal force generated by actuating the brake electric motor and transmitted to the driving wheels is opposite in phase to a periodic fluctuation of the longitudinal force of the driving wheels generated due to a periodic fluctuation of a drive torque generated by the drive electric motor in the same period (S60 to S100).SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electric vehicle in which each drive wheel is driven by a corresponding electric motor.

  In an electric vehicle such as an electric vehicle, each drive wheel is driven by a corresponding electric motor. During normal driving of the vehicle, the target drive torque of each motor is calculated based on the driver's drive operation amount, and the output of each motor is fed back so that the actual drive torque of the motor becomes the corresponding target drive torque. Be controlled.

  For example, in Patent Document 1 below, an in-wheel motor type in which a driving motor for applying a driving torque to a driving wheel and a braking motor for applying a friction braking force to the driving wheel are incorporated in the driving wheel. The electric vehicle is described. According to the electric vehicle described in Patent Document 1, the driving force and the braking force can be controlled for each driving wheel by controlling the driving motor and the braking motor.

Japanese Patent Laid-Open No. 10-285891

[Problems to be Solved by the Invention]
In an in-wheel motor type electric vehicle, a three-phase brushless AC electric motor that can generate a high driving torque and has excellent durability is generally used as an in-wheel motor that is a driving electric motor. As is well known, the three-phase AC current supplied to the three-phase brushless AC motor is composed of three AC currents called U-phase, V-phase, and W-phase. The alternating current of each phase draws a sine waveform having the same period, and adjacent phases have a phase difference of 120 degrees. For this reason, the current value supplied to the electric motor has a peak at the time when the AC current lines of each phase intersect, as viewed in a graph with the horizontal axis representing time and the vertical axis representing the current value. As a result, an output torque peak corresponding to the peak of the current value six times per cycle is generated. Therefore, a so-called torque ripple is generated due to the peak of the output torque especially when the motor is started.

  When torque ripple occurs, the driving force of the driving wheel fluctuates periodically, so that longitudinal vibration is generated in the driving wheel at the same frequency as the frequency of periodic fluctuation of the driving force. When the frequency of the front and rear vibrations of the drive wheels becomes a frequency in the resonance frequency range of the drive wheels (250 Hz or less), the front and rear vibrations of the drive wheels are transmitted to the vehicle body via a shock absorber or the like, and a low-frequency noise called a warn is generated. The vehicle occupant may feel uncomfortable.

  The main problem of the present invention is that, in an electric vehicle equipped with a braking motor for applying a braking force to the driving wheels, the front and rear vibrations and abnormal noise of the driving wheels generated due to torque ripple when the driving motor is started. It is to reduce.

[Means for Solving the Problems and Effects of the Invention]
According to the present invention, the drive wheel rotatably supported by the wheel support member, the drive motor that is supported by the wheel support member and generates the drive torque for driving the drive wheel, and the wheel support member An electromagnetic brake device that generates a braking force to be supported and brakes the drive wheel; and a brake control device that controls the electromagnetic brake device, the electromagnetic brake device rotating with the drive wheel; A friction member that is pressed against the rotating body, and an electromagnetic actuator that applies a pressing force to the friction member. The electromagnetic actuator includes a brake motor and a rotational torque of the brake motor. There is provided an electric vehicle having a conversion device for converting into an electric vehicle.

  The electromagnetic brake device includes a transmission mechanism that converts a rotational torque that periodically varies in the brake motor into a longitudinal force that periodically varies and transmits the force to the drive wheels from the electromagnetic brake device. The brake control device is configured such that when the driving motor rotates at a rotational speed equal to or less than a reference value without the electromagnetic brake device generating a braking force, the longitudinal force transmitted to the driving wheels by the transmission mechanism. The pressing force is applied to the friction member in such a manner that the periodic fluctuations of the driving wheel are opposite in phase to the periodic fluctuations of the longitudinal force of the driving wheels caused by the periodic fluctuations of the driving torque. A rotational torque that varies periodically is generated by the brake motor within a range that is not applied.

  According to the above configuration, when the drive motor is rotating at a rotational speed equal to or less than the reference value during non-braking, the brake motor is operated to generate a periodically varying rotational torque, and the transmission mechanism The periodically changing rotational torque is converted into a periodically changing longitudinal force and transmitted to the drive wheels. The periodic fluctuation of the longitudinal force transmitted to the driving wheel by the transmission mechanism is in the opposite phase with the same period as the periodic fluctuation of the longitudinal force of the driving wheel caused by the periodic fluctuation of the driving torque.

  Therefore, a longitudinal force that partially opposes the longitudinal force acting on the drive wheel due to the torque ripple is applied to the drive wheel. Therefore, the amplitude of the longitudinal vibration of the drive wheel caused by torque ripple is reduced, and the longitudinal vibration transmitted to the vehicle body via a shock absorber or the like is reduced, thereby causing the vehicle occupant to feel uncomfortable. Noise can be reduced.

  The brake motor is operated in a range in which no pressing force is applied to the friction member. Therefore, when generating a longitudinal force that partially opposes the longitudinal force acting on the drive wheels due to torque ripple, unnecessary braking force is applied to the drive wheels and the electric vehicle is unnecessarily decelerated. Can be avoided.

It is a schematic block diagram which shows the electric vehicle concerning embodiment of this invention comprised as an in-wheel motor type four-wheel drive vehicle. It is sectional drawing which looked at the in-wheel motor and electromagnetic brake device of the left front wheel from the front of a vehicle. FIG. 3 is a view of the electromagnetic brake device shown in FIG. 2 viewed from the inner side of the vehicle in the lateral direction of the vehicle. It is a flowchart which shows the control routine of the electromagnetic brake device in embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing an electric vehicle 10 according to an embodiment of the present invention applied to an in-wheel motor type four-wheel drive vehicle. The electric vehicle 10 has left and right front wheels 12FL and 12FR that are steering wheels, and left and right rear wheels 12RL and 12RR that are non-steering wheels. The wheels 12FL to 12RR are drive wheels, and are driven by applying drive torque independently from the in-wheel motors 16FL to 16RR incorporated in the corresponding wheels. The wheels 12FL to 12RR are provided with electromagnetic brake devices 18FL to 18RR that generate a braking force for braking the corresponding wheels, respectively.

  Although not shown in detail in FIG. 1, the in-wheel motors 16FL to 16RR of the embodiment are three-phase brushless AC motors capable of controlling the drive torque and the rotational speed, and drive torques for driving the corresponding wheels. It functions as a drive motor that generates The in-wheel motors 16FL to 16RR also function as regenerative generators during braking and preferably generate regenerative braking force, but regenerative braking may not be performed.

  As shown in FIGS. 2 and 3, the left front wheel 12FL is rotatably supported around the rotation axis 22 by the wheel support member 20, and the in-wheel motor 16 FL is accommodated in the wheel support member 20. ing. The wheel support member 20 is connected to the vehicle body 21 by a suspension arm not shown in FIGS. The wheel support member 20 is connected to the lower end of a shock absorber 24 connected to the vehicle body 21 at the upper end. Note that the lower end of the shock absorber 24 may be connected to a suspension arm or the like.

  Although not shown in detail in FIGS. 2 and 3, the in-wheel motor 16 FL includes a stator and a rotor disposed in the wheel support member 20. The stator is supported by the wheel support member 20 so as not to rotate around the rotation axis 22, and the rotor can rotate relative to the stator around the rotation axis 22. A disc-shaped brake rotor 26 and a spindle 28 that are integral with each other are connected to the rotor, and a wheel 30 of the left front wheel 12FL is connected to the spindle 28 by a plurality of bolts (not shown). The brake rotor 26 extends perpendicularly to the rotation axis 22 and functions as a rotating body that rotates together with the left front wheel 12FL.

  In addition to the brake rotor 26, the electromagnetic brake device 18 FL includes a brake pad 32 that functions as a friction member, an electromagnetic actuator 34, and a brake caliper 36. The brake pad 32 has a bottomed polygonal cylindrical shape and extends parallel to the rotation axis 22. The brake pad 32 is supported by the brake caliper 36 so that the brake pad 32 can be displaced with respect to the brake caliper 36 in a direction perpendicular to the plate surface of the brake rotor 26 and cannot rotate with respect to the brake caliper 36. The electromagnetic actuator 34 applies a pressing force for pressing the brake pad 32 against the brake rotor 26 to the brake pad 32.

  The brake caliper 36 has an outer plate portion 36SO and an inner plate portion 36SI extending in an arc shape on both sides of the outer peripheral portion of the brake rotor 26, and a connection portion 36C that integrally connects the outer peripheral portions of these plate portions. ing. A friction material 38 is fixed to the outer surface of the bottom wall of the brake pad 32, and a friction material 40 is fixed to the inner surface of the outer plate portion 36SO. As will be described later, the brake caliper 36 is supported by the wheel support member 20 so as to be displaceable with respect to the wheel support member 20 in a direction perpendicular to the plate surface of the brake rotor 26. Therefore, the brake pad 32 and the brake caliper 36 function as a friction member that generates a frictional force when pressed against the brake rotor 26.

  One end of brackets 42 and 43 extending substantially horizontally are fixed to the lower and upper ends of the inner plate portion 36SI of the brake caliper 36 by means such as welding. A pin 44 that is fixed to the wheel support member 20 and extends parallel to the rotation axis 22 is inserted at the tip of the bracket 42. Therefore, the lower end of the brake caliper 36 is supported by the wheel support member 20 so as to be displaceable with respect to the brake rotor 26 in a direction perpendicular to the plate surface of the brake rotor 26 and to be pivotable around the pin 44.

  A long groove 46 extending in the vertical direction is provided at the tip of the bracket 43, and a pin 48 that is fixed to the wheel support member 20 and extends in parallel with the rotation axis 22 is inserted into the long groove 46. Therefore, the upper end of the brake caliper 36 can be displaced relative to the brake rotor 26 in the direction perpendicular to the plate surface of the brake rotor 26 and can be displaced vertically relative to the wheel support member 20. On the other hand, it cannot be displaced in the vehicle front-rear downward direction.

  The electromagnetic actuator 34 includes a brake motor 50 and a conversion device 52. The brake motor 50 may be either an AC motor or a DC motor, but is preferably a three-phase brushless AC motor, like the in-wheel motor 16FL. Note that the brake motor 50 may be a smaller and lower-power motor than the in-wheel motors 16FL to 16RR.

  The conversion device 52 includes a large-diameter gear 54 fixed to the shaft of the brake motor 50 and a small-diameter gear 58 fixed to the small-diameter portion of the screw shaft 56 and meshing with the gear 54. The screw shaft 56 extends along an axis parallel to the rotation axis 22. Although not shown in FIGS. 2 and 3, the screw shaft 56 has a male screw, and the male screw is screwed into the female screw of the brake pad 32. As described above, since the brake pad 32 is supported by the brake caliper 36 so as not to rotate, when the screw shaft 56 rotates, the brake pad 32 is moved in a direction perpendicular to the plate surface of the brake rotor 26.

  When the pressing force that presses the brake pad 32 against the brake rotor 26 is a braking pressing force, the conversion device 52 converts the rotational torque of the brake motor 50 into the braking pressing force. Since the gears 54 and 58 reduce the rotational speed of the shaft of the brake motor 50 and transmit it to the screw shaft 56, the gears 54 and 58 increase the rotational torque of the shaft of the brake motor 50 and transmit it to the screw shaft 56.

  When the brake pad 32 is pressed against the brake rotor 26, the reaction force of the pressing force is applied from the brake rotor 26 to the brake pad 32 and further transmitted to the screw shaft 56. Although not shown in FIGS. 2 and 3, a bearing that rotatably supports the screw shaft 56 is provided in the brake caliper 36, and the reaction force transmitted to the screw shaft 56 is transmitted to the brake caliper via the bearing. 36. Therefore, since the brake caliper 36 is moved in the direction approaching the wheel support member 20, the friction materials 38 and 40 are pressed against the brake rotor 26 in the direction approaching each other on both sides of the brake rotor 26, and the braking force is generated by these frictions. Is generated.

  During non-braking, the brake pad 32 and the brake caliper 36 are positioned at the standby position with respect to the brake rotor 26. In the standby position, the friction materials 38 and 40 are not pressed against the brake rotor 26 or are slightly spaced from the brake rotor 26. On the other hand, at the time of braking, the brake motor 50 is operated, and the rotational torque of the brake motor 50 is converted into a brake pressing force by the conversion device 52, whereby the brake pad 32 is pressed against the brake rotor 26.

  Further, as will be described in detail later, if the front-rear vibration occurs in the left front wheel 12FL during non-braking due to the torque ripple of the in-wheel motor 16FL, the brake motor 50 is adjusted so that the rotational torque fluctuates periodically. Actuated. The brake motor 50 vibrates due to the inertia of the rotor due to periodic fluctuations in the rotational torque, and the brake caliper 36 is vibrated. In this case, the brake motor 50 is rotated in a direction opposite to the rotation direction for bringing the brake pad 32 close to the brake rotor 26 so that unnecessary braking force is not applied to the left front wheel 12FL.

  When the brake caliper 36 is vibrated, the brake caliper 36 is reciprocally pivoted with respect to the wheel support member 20 around the pin 44 as shown by the broken double-headed arrow in FIG. As described above, the brake caliper 36 is connected to the wheel support member 20 at the upper end by the pin 48 so as to be displaceable in the vertical direction with respect to the wheel support member 20 but not in the vehicle longitudinal direction. . Therefore, as shown by the solid double-headed arrow in FIG. 3, the upper end of the brake caliper 36 is at the same frequency as the longitudinal vibration frequency of the left front wheel 12FL and in the opposite phase to the longitudinal vibration of the left front wheel 12FL. It can be vibrated.

  Accordingly, the upper part of the brake caliper 36 and the electromagnetic actuator 34 are vibrated in the opposite phase to the longitudinal vibration of the left front wheel 12FL at the same frequency as the longitudinal vibration frequency of the left front wheel 12FL. As a result, the brake caliper 36 and the electromagnetic actuator 34 apply a longitudinal force varying at the above frequency to the wheel support member 20, thereby reducing the amplitude of the longitudinal vibration of the left front wheel 12FL. In this case, the brake caliper 36 functions as a transmission mechanism that converts the rotational torque that fluctuates periodically of the brake motor 50 into a longitudinal fluctuating longitudinal force and transmits it to the left front wheel 12FL.

  The right front wheel 12FR and the left and right rear wheels 12RL and 12RR are also supported by the same support structure as the support structure of the left front wheel 12FL described above. Further, the in-wheel motors 16FR to 16RR and the electromagnetic brake devices 18FR to 18RR are configured similarly to the in-wheel motor 16FL and the electromagnetic brake device 18FL, respectively, and operate similarly.

  When the electric vehicle 10 travels, the driving force of the in-wheel motors 16FL to 16RR is based on the accelerator opening degree Acc detected by the accelerator opening sensor 60, and the output of the in-wheel motors 16FL to 16RR is the electronic driving device 62 for driving. It is controlled by being controlled by. The accelerator opening Acc indicates the amount of depression of the accelerator pedal 64, that is, the amount of driving operation of the driver. The regenerative braking force of the in-wheel motors 16FL to 16RR is controlled by the braking electronic control device 66 via the driving electronic control device 62.

  Although not shown in the drawing, the drive circuit of the drive electronic control unit 62 includes an inverter and a converter for each wheel, as is well known. The drive circuit converts a direct current from the battery into a two-phase alternating current during driving, further converts the two-phase alternating current into a three-phase alternating current, and supplies the three-phase alternating current to the in-wheel motors 16FL to 16RR. On the other hand, at the time of regenerative braking, the drive circuit converts the three-phase alternating current from the in-wheel motors 16FL to 16RR into a two-phase alternating current, and further converts the two-phase alternating current into a direct current to the battery. Supply and charge the battery.

  The electromagnetic brake device 18FL and the like are controlled according to the flowchart shown in FIG. When a braking operation is performed by the driver, the electromagnetic brake devices 18FL to 18RR are controlled by the braking electronic control device 66 based on the pedal force Fbp detected by the pedal force sensor 68, so that the wheels 12FL to 12RR are given. Braking force is controlled (normal control of braking force). The stepping force Fbp is a stepping force on the brake pedal 70 and indicates the amount of braking operation performed by the driver.

  When no braking operation is performed by the driver, when the longitudinal vibrations caused by the torque ripples of the in-wheel motors 16F to 16RR are not generated in the wheels 12FL to 12RR, the electromagnetic brake device 18FL and the like are in an inoperative state. Maintained. That is, the brake pad 32 and the brake caliper 36 are positioned at the standby position with respect to the brake rotor 26.

  On the other hand, when the front and rear vibration caused by the torque ripple of the in-wheel motor occurs in any of the wheels 12FL to 12RR in a situation where the braking operation is not performed by the driver, as described above by the corresponding electromagnetic brake device. The brake caliper 36 is vibrated. Accordingly, the brake caliper 36 and the electromagnetic actuator 34 apply a longitudinal force that periodically fluctuates in the opposite phase at the same frequency as the longitudinal force of the longitudinal vibration of the wheel 12FL or the like to the corresponding wheel, thereby reducing the longitudinal vibration of the wheel. Is done.

  Although not shown in detail in the figure, the driving electronic control device 62 and the braking electronic control device 66 include a microcomputer and exchange necessary information with each other. Each microcomputer has a general configuration in which a CPU, a ROM, a RAM, and an input / output port device are connected to each other via a bidirectional common bus.

  A signal indicating the accelerator opening Acc from the accelerator opening sensor 60 is input to the drive electronic control device 62. The in-wheel motors 16FL to 16RR incorporate rotation angle sensors (resolvers) 72FL to 72RR and torque sensors 74FL to 74RR, respectively. The drive electronic control unit 62 includes a rotation angle (electrical angle) φi and a drive torque Ti (i = fl, fr) of the corresponding in-wheel motors 16FL to 16RR from the rotation angle sensors 72FL to 72RR and the torque sensors 74FL to 74R, respectively. , Rl, and rr) are input. Further, information necessary for traveling control of the vehicle 10 such as a signal indicating the vehicle speed V from the vehicle speed sensor 76 is input to the drive electronic control device 62.

  A signal indicating the pedaling force Fbp detected by the pedaling force sensor 68 is input to the braking electronic control unit 66, and an on / off signal from the brake switch 78, that is, whether or not a braking operation is being performed by the driver. A signal is input. The braking electronic control device 66 reduces the longitudinal vibration of the wheels 12FL to 12RR in addition to the control of the electromagnetic brake devices 18FL to 18RR for controlling the braking force as described above according to the flowchart shown in FIG. The electromagnetic brake devices 18FL to 18RR are controlled.

  Next, the control of the electromagnetic brake devices 18FR to 18RR executed by the braking electronic control device 66 in the embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 4 is performed when the ignition switch not shown in the figure is turned on, for example, the electromagnetic brake device for each wheel in the order of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel. Are repeatedly executed at predetermined time intervals. In the following description, the wheel longitudinal vibration reduction control according to the flowchart shown in FIG. 4 is simply referred to as “control”.

  First, in step 10, signals indicating the rotation angle φi of the in-wheel motors 16FL to 16RR detected by the rotation angle sensors 72FL to 72RR, respectively, are read.

  In step 20, it is determined whether or not the electromagnetic brake devices 18FL to 18RR are generating a braking force by determining whether or not the brake switch 78 is on, for example. When a negative determination is made, control proceeds to step 40, and when an affirmative determination is made, control proceeds to step 30.

  In step 30, the electromagnetic brake devices 18FL to 18RR for normal control of the braking force are controlled. That is, by controlling the electromagnetic brake devices 18FL-18RR based on the pedaling force Fbp detected by the pedaling force sensor 68, the braking force according to the driver's braking request is applied to the wheels 12FL-12RR.

  In step 40, for example, the rotational speed Vm of the in-wheel motors 16FL to 16RR is calculated by calculating the time differential value of the rotation angle φi of the in-wheel motors 16FL to 16RR. Further, it is determined whether or not the rotational speed Vm is equal to or less than the reference value Vm0 (positive constant), that is, the situation at the start of rotation of the in-wheel motors 16FL to 16RR where vibration due to torque ripple is likely to occur. Whether or not is determined. When a negative determination is made, control proceeds to step 90, and when an affirmative determination is made, control proceeds to step 50.

  In step 50, the amplitude Da of the drive current (three-phase alternating current) supplied to the in-wheel motors 16FL to 16RR is obtained. Further, it is determined whether or not the amplitude Da of the drive current is greater than or equal to a reference value Da0 (positive constant), that is, whether or not the vibration due to torque ripple is likely to occur at a large amplitude. . When a negative determination is made, control proceeds to step 90, and when an affirmative determination is made, control proceeds to step 60.

  Note that the determination in step 40 is also an affirmative determination even when the rotational speed Vm of the in-wheel motors 16FL to 16RR decreases, such as when the vehicle 10 finishes traveling. However, since the determination in step 50 is a negative determination, in a situation where the rotational speed Vm of the in-wheel motors 16FL to 16RR decreases and vibration due to torque ripple does not occur in the in-wheel motor, steps 60 to 100 described later are performed. It is not executed unnecessarily.

In step 60, based on the rotational speed Vm of the in-wheel motors 16FL to 16RR calculated in step 40, the target frequency ft of the drive current supplied to the brake motor 50 is calculated according to the following equation (1). . Note that “6” in the following equation (1) corresponds to the occurrence of 6 peaks per cycle in the current value supplied to the in-wheel motors 16FL to 16RR.
ft = (Vm / 2π) · 6 (1)

In step 70, K is set to a preset gain (positive constant), and θth1 to θth3 are set to experimentally obtained phase differences in advance to the brake motor 50 according to the following equations (2) to (4). Three-phase AC currents P1 to P3 of the supplied drive command current are calculated. Θth1 to θth3 vibrates the brake caliper 36 by the rotation of the brake motor 50, and vibrates the upper end of the brake caliper 36 in the front-rear direction with the same frequency as that of the front-rear vibrations of the wheels 12FL to 12RR and in reverse phase. For the phase difference.
P1 = K.Da.sin (2.pi..ft.Vm + .theta.th1) (2)
P2 = K.Da.sin (2.pi..ft.Vm + .theta.th2) (3)
P3 = K.Da.sin (2.pi..ft.Vm + .theta.th3) (4)

  In step 80, it is determined whether or not the brake pad 32 is at the terminal position of the movement away from the brake rotor 26, that is, the brake motor 50 is further rotated in the direction opposite to the direction in which the braking force is increased. A determination is made as to whether or not it cannot be performed. When a negative determination is made, the control proceeds to step 100, and when an affirmative determination is made, the brake motor 50 is operated so that the brake pad 32 and the brake caliper 36 are returned to the standby position in step 90. When the brake pad 32 and the brake caliper 36 are already in the standby position, the brake motor 50 is not rotated.

  In step 100, three-phase alternating currents P1 to P3 of the drive command current are output to the brake motor 50. Therefore, the brake motor 50 is operated to vibrate at the target frequency ft, and thus the brake caliper 36 is vibrated so that the upper end portion of the brake caliper 36 vibrates in the front-rear direction.

  As can be understood from the above description, when the vehicle is not braked (step 20) and vibrations caused by torque ripple are likely to occur in the in-wheel motors 16FL to 16RR (steps 40 and 50), steps 60 to 100 are performed. Is executed. That is, the brake caliper 36 is vibrated by the rotation of the brake motor 50, and the upper end of the brake caliper 36 and the electromagnetic actuator 34 are vibrated in the front-rear direction with the same frequency as the front-rear vibration of the wheels 12FL to 12RR and in the opposite phase. It is done.

  Therefore, a longitudinal force that partially opposes the longitudinal force acting on the wheels 12FL to 12RR due to the torque ripple is applied from the brake caliper 36 to the wheels 12FL to 12RR. Accordingly, the amplitude of the longitudinal vibration of the wheels 12FL to 12RR caused by the torque ripple is reduced, and the longitudinal vibration transmitted to the vehicle body via a shock absorber or the like is reduced, thereby causing the vibration to the vehicle occupant. Unpleasant noise that causes discomfort can be reduced.

  Note that the total mass of the brake caliper 36 and the electromagnetic actuator 34 is much smaller than the total mass of the wheel, the in-wheel motor and the wheel support member 20, and therefore the longitudinal force applied from the brake caliper 36 to the wheels 12FL to 12RR. The size of is also small. However, according to the embodiment, the amplitude of the longitudinal vibrations of the wheels 12FL to 12RR can be reliably reduced as compared with the case where the longitudinal force for damping is not applied from the brake caliper 36 to the wheels 12FL to 12RR. .

  In particular, in the embodiment, when the brake caliper 36 is vibrated, the brake motor 50 rotates in a direction in which the brake pad 32 moves away from the brake rotor 26, that is, in a direction opposite to the direction in which the braking force is increased. Is done. Therefore, it is possible to reliably avoid unnecessary braking force being applied to the wheels 12FL to 12RR by controlling the electromagnetic brake devices 18FR to 18RR for reducing the vibration of the wheels 12FL to 12RR.

  In the embodiment, in step 50, it is determined whether or not the vibration due to torque ripple is likely to occur at a large amplitude based on the amplitude Da of the drive current supplied to the in-wheel motor. Done. When the vibration due to torque ripple is not likely to occur at a large amplitude, steps 60 to 100 are not executed. Therefore, even in a situation where vibration due to torque ripple is likely to occur, the brake motor 50 is operated unnecessarily when the amplitude of the vibration does not increase and the possibility that the vehicle occupant feels abnormal noise is low. Further, unnecessary vibration of the brake caliper 36 can be avoided.

  Furthermore, in the embodiment, in step 60, the target frequency ft of the drive current supplied to the brake motor 50 is calculated based on the rotational speed Vm of the in-wheel motors 16FL to 16RR. Therefore, for example, the target frequency ft of the drive current is easily calculated as compared with the case where the longitudinal vibration of the wheels 12FL to 12RR is detected by the longitudinal acceleration sensor and the target frequency ft of the drive current is calculated based on the detection result. Furthermore, the possibility that the longitudinal vibration of the brake caliper 36 is delayed with respect to the longitudinal vibration of the wheel can be reduced.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. This will be apparent to those skilled in the art.

  For example, in the above-described embodiment, whether or not the electromagnetic brake devices 18FL to 18RR are generating braking force is determined by determining whether or not the brake switch 78 is turned on in step 20. However, whether or not the electromagnetic brake device 18FL or the like is generating a braking force may be determined based on a command current to the electromagnetic brake device.

  In the above-described embodiment, it is determined whether or not the amplitude Da of the drive current supplied to the in-wheel motor 16FL or the like in step 50 is greater than or equal to the reference value Da0, that is, the amplitude caused by the vibration caused by torque ripple is large. Whether or not the amplitude is likely to occur is determined. However, this determination may be omitted.

  Further, in the above-described embodiment, the brake caliper 36 functions as a transmission mechanism that converts the periodically changing rotational torque of the brake motor 50 into a periodically changing longitudinal force and transmits it to the drive wheels. However, this transmission mechanism may be configured by a member other than the brake caliper 36.

  In the above-described embodiment, when the brake caliper 36 is vibrated, the brake pad 32 is moved from the standby position to the end position, and when the brake pad 32 reaches the end position, the brake caliper 36 is not vibrated. The brake pad 32 is returned to the standby position. However, when the longitudinal vibration due to the torque ripple of the in-wheel motor 16FL continues even when the brake pad 32 reaches the end position, the steps 60, 70 and 100 are also performed when the brake pad 32 is returned to the standby position. The brake caliper 36 may be vibrated by executing the above.

  In the above-described embodiment, the brake caliper 36 is pivotally supported by the wheel support member 20 at the lower end that is lower than the rotation axis 22 of the wheel, and is supported by the upper end that is higher than the rotation axis 22. A longitudinal force is applied to the member 20. However, the position where the longitudinal force is applied to the wheel support member 20 is set to a position having substantially the same height as the rotation axis 22, and the wheel longitudinal vibration is corrected more effectively than in the embodiment. Also good.

  Further, in the above-described embodiment, the in-wheel motors 16FL to 16RR respectively apply driving forces to the corresponding wheels 12FL to 12RR independently of each other. However, the present invention may be applied to a vehicle in which the front two wheels or the rear two wheels are drive wheels driven by driven wheels or other drive means.

  In the above-described embodiment, the rotors of the in-wheel motors 16FL to 16RR are directly connected to the spindles 28 of the wheels 12FL to 12RR. However, a speed reducer may be provided between the rotors of the in-wheel motors 16FL to 16RR and the spindle 28. Furthermore, although the driving motor that applies driving force to the wheels 12FL to 12RR is the in-wheel motor 16FL to 16RR, the present invention may be applied to a vehicle that is an on-board motor in which the driving motor is mounted on the vehicle body. Good.

DESCRIPTION OF SYMBOLS 10 ... Electric vehicle, 12FL-12RR ... Wheel, 16FL-16RR ... In-wheel motor, 16FL-16RR ... Electromagnetic brake device, 20 ... Wheel support member, 26 ... Brake rotor, 32 ... Brake pad, 34 ... Electromagnetic actuator, 36 ... Brake caliper, 50 ... brake motor, 52 ... converter, 62 ... driving electronic control device, 66 ... braking electronic control device, 72FL to 72RR ... rotation angle sensor

Claims (1)

A drive wheel rotatably supported by a wheel support member; a drive motor that is supported by the wheel support member and generates a drive torque for driving the drive wheel; and the drive wheel supported by the wheel support member. An electromagnetic brake device that generates a braking force for braking, and a brake control device that controls the electromagnetic brake device, the electromagnetic brake device rotating with the drive wheel, and the rotating body A friction member to be pressed; and an electromagnetic actuator that applies a pressing force to the friction member, wherein the electromagnetic actuator is a brake motor, and a conversion device that converts rotational torque of the brake motor into the pressing force. In an electric vehicle having
The electromagnetic brake device has a transmission mechanism that converts a rotational torque that periodically fluctuates in the brake motor to a longitudinal fluctuating force that is periodically fluctuated and transmits the force to the drive wheels from the electromagnetic brake device.
The brake control device is configured such that when the driving motor rotates at a rotational speed equal to or less than a reference value without the electromagnetic brake device generating a braking force, the longitudinal force transmitted to the driving wheels by the transmission mechanism. The pressing force is applied to the friction member in such a manner that the periodic fluctuations of the driving wheel are opposite in phase to the periodic fluctuations of the longitudinal force of the driving wheels caused by the periodic fluctuations of the driving torque. An electric vehicle that generates a rotational torque that varies periodically by the brake motor within a range that is not applied.

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