Electronic control device for vehicle

Abstract

To provide a control device for a vehicle that is able to flexibly restrict beat sound according to a traveling state.SOLUTION: A control device for a vehicle includes: an inverter configured to supply power to each of drive units configured to drive two different wheels by means of respective motors; and a control unit configured to control the inverter. The control unit variably controls a switching timing of a switching element of the inverter so that a frequency difference X between noise vibrations NVL, NVR generated in the respective drive units deviates from a beat sound generation ranges A to B in which beat sound is generated by synthesis of the noise vibrations NVL, NVR.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle.

Background Art

[0002] Patent Document 1 discloses a technique for suppressing a howling sound generated by interference of sounds generated from a reduction mechanism or a motor of each in-wheel motor by varying combinations of the number of teeth of the reduction mechanisms between at least one combination of in-wheel motors in a vehicle having in-wheel motors each including a motor and a reduction mechanism for each wheel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a traveling vehicle, a howling sound is generated according to its driving state. For this reason, in the technique described in Patent Document 1 in which combinations of the number of teeth of the reduction mechanisms are varied to suppress a howling sound of a specific frequency, it may be difficult to sufficiently suppress the howling sound generated according to the traveling state.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for a vehicle that can flexibly suppress a howling sound according to a traveling state.

Means for Solving the Problems

[0006] In order to achieve the above object, a vehicle control device according to the present invention includes an inverter that supplies power to drive units that drive two different wheels by motors respectively, and a control unit that controls the inverter. The control unit variably controls the switching timing of the switching elements of the inverter so that the frequency difference of the noise vibrations generated in each of the drive units is outside the beat sound generation range where a beat sound is generated by the synthesis of the noise vibrations.

[0007] According to the vehicle having this configuration, by variably controlling the switching timing of the switching elements of the inverter that supplies power to the motors of each wheel according to the frequency difference, the beat sound can be flexibly suppressed according to the running state. Further, compared with changing the combination of the gears of the speed reduction mechanism to suppress the beat sound, an increase in cost and an increase in weight can be suppressed.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a vehicle control device that can flexibly suppress a beat sound according to the running state.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] FIG. 1 is a schematic configuration diagram of a vehicle including a control device for a vehicle according to this embodiment.

[0012] As shown in FIG. 1, the control device of the vehicle 1 according to this embodiment is mounted on a vehicle including two front wheels 11 and 12 and two rear wheels 13 and 14. The control device of the vehicle 1 includes, for example, inverters 31 to 34 and a control unit 41. The vehicle 1 is, for example, an all-wheel drive vehicle in which all the wheels 11 to 14 are drive wheels.

[0013] The drive wheels 11 to 14 each have a motor 21 to 24, and the driving force of these motors 21 to 24 is transmitted to the wheels 11 to 14. The drive unit is configured by the wheels 11 to 14 and the motors 21 to 24. The motors 21 to 24 of each drive unit are each powered from the inverters 31 to 34. The inverters 31 to 34 may be included in the drive unit.

[0014] Each of the inverters 31 to 34 is connected to the control unit 41 and is controlled by the control unit 41. Each of the inverters 31 to 34 has a switching element, and is configured to be able to change the switching timing between on and off of the switching element.

[0015] The vehicle 1 travels by driving the motors 21 to 24 of each drive unit by power supply from the inverters 31 to 34 controlled by the control unit 41, and rotating the wheels 11 to 14 by the driving force of the motors 21 to 24.

[0016] Here, in the vehicle 1 including a drive unit including the motors 21 to 24 that rotationally drive the respective wheels 11 to 14, noise vibration NV occurs during power conversion in the inverters 31 to 34 of each drive unit.

[0017] FIG. 2 is a graph exemplarily showing noise vibration NVL in the drive units of the left wheels 11 and 13 at the front and rear, and noise vibration NVR in the drive units of the right wheels 12 and 14 at the front and rear.

[0018] As shown in FIG. 2, for example, when turning the vehicle 1, the rotational speeds RL of the motors 21 and 23 of the left wheels 11 and 13 and the rotational speeds RR of the motors 22 and 24 of the right wheels 12 and 14 will be different. For example, when turning the vehicle 1 to the right, the rotational speed RR of the motors 22 and 24 of the right wheels 12 and 14 will be lower than the rotational speed RL of the motors 21 and 23 of the left wheels 11 and 13.

[0019] At this time, in the left and right drive units including the inverters 31 to 34 of the carrier frequencies CFL and CFR, the frequency FL of the noise vibration NVL generated in the left drive unit is lower than the frequency FR of the noise vibration NVR generated in the right drive unit.

[0020] And when the frequency difference X, which is the deviation between the frequency FR of the right noise vibration NVR and the frequency FL of the left noise vibration NVL, falls within a specific beat sound generation range A to B, these noise vibrations NVL and NVR overlap to generate a beat sound as a humming sound.

[0021] Note that when the frequency difference X is small and does not reach the beat sound generation range A to B, or when the frequency difference X is large and exceeds the beat sound generation range A to B, the generation of the humming sound due to the overlap of these noise vibrations NVL and NVR is suppressed.

[0022] FIG. 3 is a graph exemplarily showing that the beat sound noise increases due to the beat sound generated in the drive unit on the front wheel side and the beat sound generated in the drive unit on the rear wheel side.

[0023] As shown in FIG. 3, when the waveform BFF of the frequency of the beat sound generated by the drive unit on the front wheel side and the waveform BFR of the frequency of the beat sound generated by the drive unit on the rear wheel side are in the same phase, the beat sound level of the waveform BFC synthesized by overlapping the two waveforms will increase. That is, the closer the two waveforms are to the same phase, the higher the beat sound level will be.

[0024] To solve this problem, it is possible to reduce the beat sound noise by adjusting so that the waveform BFF of the frequency of the beat sound generated by the drive unit on the front wheel side and the waveform BFR of the frequency of the beat sound generated by the drive unit on the rear wheel side are in opposite phases. This will be described with reference to FIG. 4.

[0025] As shown in FIG. 4, when the waveform BFF of the frequency of the beat sound generated by the drive unit on the front wheel side and the waveform BFR of the frequency of the beat sound generated by the drive unit on the rear wheel side are in opposite phases, the beat sound level of the waveform BFC synthesized by the two waveforms canceling each other out will decrease. That is, the closer the two waveforms are to the opposite phase, the lower the beat sound level will be.

[0026] In order to change the phases of the two waveforms BFF and BFR, it is preferable that the control unit 41 changes the switching timing of the switching elements of the inverters 31 and 32 on the front wheel side and the switching timing of the switching elements of the inverters 33 and 34 on the rear wheel side. Specifically, the control unit 41 adjusts the switching timing of each switching element of the inverters 31 to 34 so that the two waveforms BFF and BFR are in opposite phases.

[0027] In the control device of the vehicle 1 according to the present embodiment, in order to suppress the humming sound, the control unit 41 controls the switching elements of the inverters 31 to 34 as follows, for example. FIG. 5 is a flowchart for explaining an example of the control procedure by the control unit 41.

[0028] First, information on the tire diameters, vehicle speed, and steering angle of each wheel 11 to 14 is acquired (step S101).

[0029] Subsequently, based on the information of the tire diameters, vehicle speeds, and steering angles of the acquired respective wheels 11 to 14, the turning radius of the vehicle 1 and the rotational speeds of the respective wheels 11 to 14 are obtained (Steps S102, S103).

[0030] Subsequently, based on the information of the tire diameters, vehicle speeds, and steering angles of the respective wheels 11 to 14, the turning radius of the vehicle 1, and the rotational speeds of the respective wheels 11 to 14, the frequencies FL, FR of the noise vibration NVL, NVR in each drive unit are calculated (Step S104).

[0031] Subsequently, a frequency difference X, which is the deviation between the calculated frequencies FL, FR of the noise vibration NVL, NVR, is obtained (Step S105). Subsequently, it is determined whether the frequency difference X falls within the booming sound generation range A to B (A ≤ X ≤ B) (Step S106).

[0032] When it is determined that the frequency difference X falls within the booming sound generation range A to B (Step S106; YES), the switching timing of the switching elements of the inverters 31 to 34 is changed so that the frequency difference X falls outside the booming sound generation range A to B (Step S107).

[0033] As described above, according to the control device for the vehicle 1 according to the present embodiment, by variably controlling the switching timing of the switching elements of the inverters 31 to 34 that supply power to the motors 21 to 24 of the respective wheels 11 to 14 according to the frequency difference X, it is possible to flexibly suppress the booming sound according to the running state. Further, compared with changing the combination of gears of the speed reduction mechanism to suppress the booming sound, it is possible to suppress an increase in cost and an increase in weight.

[0034] In the above-described embodiments, the case where the vehicle has four wheels has been described, but the present invention is not limited thereto. When the number of wheels exceeds four, the phase difference may be changed according to the increased number of wheels. For example, in the case of four wheels including two front wheels and two rear wheels described above, the phases of the frequencies of the front wheels and the rear wheels are shifted by 180 degrees to have opposite phases. However, in the case of six wheels including two front wheels, two middle wheels, and two rear wheels, it is preferable to shift the phases of the frequencies of the front wheels, the rear wheels, and the middle wheels by 120 degrees each. The case of six wheels will be described with reference to FIG. 6.

[0035] As shown in FIG. 6, it is preferable to adjust the switching timing of the switching elements of the inverter so that the phases of the waveform BFF of the frequency of the beat sound generated by the drive unit on the front wheel side, the waveform BFR of the frequency of the beat sound generated by the drive unit on the rear wheel side, and the waveform BFM of the frequency of the beat sound generated by the drive unit on the middle wheel side are shifted by 120 degrees each. Thereby, the beat sound level of the waveform BFC synthesized by the three waveforms can be reduced.

Explanation of Reference Numerals

[0036] 1 Vehicle 11, 12, 13, 14 Wheels 21, 22, 23, 24 Motors 31, 32, 33, 34 Inverters 41 Control Unit A - B Roar Sound Generation Range CFL, CFR Carrier Frequencies NVL, NVR Noise Vibration X Frequency Difference

Claims

【Claim 1】 An inverter that supplies power to drive units that drive two different wheels respectively by motors, A control unit that controls the inverter, Comprising, The control unit variably controls the switching timing of the switching elements of the inverter so that the frequency difference of the noise vibrations generated in each of the drive units is outside the beat sound generation range where a beat sound is generated by the synthesis of the noise vibrations. A control device for a vehicle.

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