vehicle

Abstract

To provide a vehicle configured so that vibrations of a casing storing a motor body can be reduced in an in-wheel motor.SOLUTION: A vehicle is equipped with: wheels; in-wheel motors for driving the wheels; a rotation speed sensor that detects rotation speeds of the in-wheel motors; and a control device that controls the in-wheel motors, on the basis of torque target value of the in-wheel motors. The in-wheel motor comprises: a motor body; a first rotation shaft that is driven by the motor body; a second rotation shaft offset to the first rotation shaft and connected to the wheel; a torque transmission mechanism that transmits torque between the first rotation shaft and the second rotation shaft; and a casing storing the motor body and the torque transmission mechanism and supporting the first rotation shaft and the second rotation shaft. The control device can adjust the torque target value so that a time rate change of a detected value by the rotation speed sensor decreases, when the time change rate exceeds a predetermined first threshold.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The technology disclosed in this specification relates to vehicles. In particular, it relates to a vehicle equipped with an in-wheel motor for driving wheels.

Background Art

[0002] The in-wheel motor disclosed in Patent Document 1 is directly connected to the wheel without passing through a suspension. Specifically, the in-wheel motor includes a first motor, a first drive gear connected to the output shaft of the first motor, a driven gear meshing with the first drive gear, and a drive shaft of the wheel connected to the driven gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above in-wheel motor, a motor casing for housing the first motor and a gear casing for housing the driven gear are integrally formed. Therefore, the reaction force of the driven gear is applied to the motor casing. The reaction force of the driven gear vibrates the motor casing. Also, in an in-wheel motor directly connected to the wheel without passing through a suspension, for example, when the wheel crosses a step, if vibration occurs in the motor casing, noise is likely to occur in the vehicle interior. In this specification, a technology capable of reducing vibration of a casing for housing a motor body in an in-wheel motor is provided.

Means for Solving the Problems

[0005] A vehicle disclosed herein includes a wheel, an in-wheel motor for driving the wheel, a rotation speed sensor for detecting the rotation speed of the in-wheel motor, and a control device for controlling the in-wheel motor based on a torque target value of the in-wheel motor. The in-wheel motor includes a motor body, a first rotation shaft driven by the motor body, a second rotation shaft offset from the first rotation shaft and connected to the wheel, a torque transmission mechanism for transmitting torque between the first rotation shaft and the second rotation shaft, and a casing that houses the motor body and the torque transmission mechanism and supports the first and second rotation shafts. The control device can adjust the torque target value so that the time rate of change of the value detected by the rotation speed sensor decreases when the time rate of change of the value detected by the rotation speed sensor exceeds a predetermined first threshold.

[0006] For example, when a vehicle's wheels go over a bump, a disturbance occurs, and the rate of change of the motor's rotational speed over time increases. The aforementioned vehicle can monitor the rotational speed of the motor and adjust the torque target value so that the rate of change over time decreases when it exceeds a first threshold. This can reduce vibrations in the casing that houses the motor.

[0007] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0008] [Figure 1] This shows a rear side view of the electric vehicle 100 of the first embodiment. [Figure 2] Figure 1 shows a cross-sectional view along line II-II. [Figure 3] This shows a flowchart of the torque target value adjustment process performed by the control device 40 of the first embodiment. [Figure 4] The graph shows the time-dependent changes in each value in the electric vehicle 100 of the first embodiment. [Figure 5] The flowchart shows the torque target value adjustment process performed by the control device 40 of the second embodiment. [Figure 6] The graph shows the time-dependent changes in each value in the electric vehicle 100 of the second embodiment. [Modes for carrying out the invention]

[0009] In one embodiment of this technology, the control device may calculate an estimated value of the casing torque applied to the casing based on the torque target value, the rate of change over time, and a pre-stored calculation formula. In this case, the torque target value may be adjusted when the rate of change over time exceeds a predetermined first threshold and the casing torque exceeds a second threshold. With this configuration, when it is estimated that a casing torque exceeding the second threshold will be applied to the casing, the torque target value can be adjusted to reduce casing vibration.

[0010] In one embodiment of this technology, the calculation formula may be based on the moment of inertia of the first rotating shaft, the moment of inertia of the second rotating shaft, the moment of inertia of the motor body, and the reduction ratio in the torque transmission mechanism. However, in another embodiment, for example, the control device may calculate an estimated value of the casing torque based on the detection value of a torque sensor provided in the casing.

[0011] In one embodiment of this technology, when the rate of change over time exceeds the first threshold, the control device may set the value detected by the rotational speed sensor immediately before that point as the target rotational speed, and if the deviation between the value detected by the rotational speed sensor and the target rotational speed exceeds a third threshold, the torque target value may be adjusted based on the deviation. With such a configuration, feedback control can be performed using the value detected by the rotational speed sensor immediately before the disturbance occurs as the target rotational speed. This makes it possible to reduce casing vibration with relatively simple control.

[0012] (First embodiment) Figure 1 shows a rear side view of the electric vehicle 100 of the first embodiment. Figure 1 particularly shows a side view around the rear wheel 6R of the electric vehicle 100. In addition to the rear wheel 6R, the electric vehicle 100 includes a rear suspension 2, a trailing arm 4, an in-wheel motor 10, and a control device 40. For ease of understanding, in Figure 1, the in-wheel motor 10 is shown with a solid line, and the other components are shown with dashed lines. The electric vehicle 100 drives the rear wheel 6R by supplying power from a battery (not shown) to the in-wheel motor 10 located on the rear wheel 6R. The electric vehicle 100 in this specification includes not only electric vehicles but also fuel cell vehicles. In the coordinate system in the figure, FR indicates the front of the electric vehicle 100, UP indicates the top of the electric vehicle 100, and LH indicates the left of the electric vehicle 100. Hereafter, "up", "down", "left", "right", "front", and "rear" will be described based on the coordinate system in the figure.

[0013] The rear suspension 2 comprises a damper and a spring. The rear suspension 2 suppresses the transmission of vibrations during driving to the body of the electric vehicle 100. The rear suspension 2 is positioned on the inside of the vehicle (i.e., the far side of the page in Figure 1) of the trailing arm 4. The trailing arm 4 extends in the front-rear direction and is a member that connects the in-wheel motor 10 to the body of the electric vehicle 100. In the electric vehicle 100 of this embodiment, the in-wheel motor 10 is connected to the body of the electric vehicle 100 by the trailing arm 4 without going through the rear suspension 2.

[0014] The rear wheel 6R comprises a wheel 8 and a tire 9. An in-wheel motor 10 is positioned inside the tire 9. The wheel 8 covers the in-wheel motor 10 from the outside of the vehicle (i.e., the front side of the page in Figure 1). The control device 40 is a computer that controls the driving of the electric vehicle 100. Although not shown in the illustration, the control device 40 is electrically connected to various devices related to the driving of the electric vehicle 100, such as the accelerator pedal, brake pedal, and inverter, in addition to the in-wheel motor 10. For example, when the control device 40 receives the amount of depression of the accelerator pedal from the accelerator pedal, it calculates a torque target value based on that depression amount. The control device 40 supplies power corresponding to the torque target value to the in-wheel motor 10 via the inverter. As a result, the in-wheel motor 10 applies torque to the rear wheel 6R according to the amount of depression of the accelerator pedal.

[0015] As shown in Figure 2, the in-wheel motor 10 comprises a motor body 21, an input shaft 20, an output shaft 30, an input gear 22, an output gear 32, and a casing 12. The motor body 21 is a so-called radial gap motor and comprises a rotor 24, a rotor core 25, a stator coil 26, and a stator core 27. The rotor core 25 is provided on the outer circumferential surface of the rotor 24. The stator coil 26 is wound around the outer circumferential surface of the stator core 27. The stator coil 26 and the stator core 27 face the rotor core 25 from the radial direction (i.e., the vertical direction in the plane of Figure 2) of the rotor core 25, with a gap between them. Both the rotor core 25 and the stator core 27 are made of magnetic material. When current flows through the stator coil 26, a magnetic force is generated between the rotor core 25 and the stator coil 26, causing the rotor 24 to rotate.

[0016] At the radially central part of the rotor 24, the input shaft 20 is inserted. The input shaft 20 has a cylindrical shape extending along the left - right direction. The input shaft 20 is arranged coaxially with the central axis of the rotor 24. The rotational movement of the rotor 24 of the motor body 21 is transmitted to the input shaft 20. That is, the input shaft 20 is driven by the motor body 21. On the outer peripheral surface of the central part in the longitudinal direction of the input shaft 20, a resolver 29 is provided. The resolver 29 is a sensor for detecting the rotational speed of the input shaft 20.

[0017] At the left - hand end (i.e., the right - hand side of the paper in FIG. 2) of the input shaft 20, an input gear 22 is provided. The input gear 22 rotates together with the input shaft 20. In front of the input gear 22 (i.e., the lower side of the paper in FIG. 2), an output gear 32 is located. The input gear 22 and the output gear 32 are meshed with each other.

[0018] The output gear 32 is connected to the output shaft 30. Thereby, the rotation of the rotor 24 of the motor body 21 is transmitted to the output shaft 30 via the input shaft 20. In other words, the input gear 2 and the output gear 32 transmit torque between the input shaft 20 and the output shaft 30. The output shaft 30 has a cylindrical shape extending along the left - right direction. That is, the output shaft 30 extends parallel to the input shaft 20.

[0019] The casing 12 houses the motor body 21, the input gear 22, and the output gear 32. The casing 12 includes a first casing 14, a second casing 16, and a third casing 18. Each of the casings 14, 16, 18 overlaps in the left - right direction. The first casing 14 located closest to the inside of the vehicle (i.e., the left - hand side of the paper in FIG. 2) supports the motor body 21 from the inside of the vehicle. A bearing 11 is provided between the rotor 24 of the motor body 21 and the first casing 14. The bearing 11 is a so - called radial ball bearing and includes rolling elements, an outer ring, and an inner ring that slidably supports the rolling elements in the circumferential direction of the rotor 24.

[0020] The second casing 16 covers the motor body 21 from the outside of the vehicle (i.e., the right side of the paper in FIG. 2). A bearing 11 is provided between the input shaft 20 and the second casing 16. The first casing 14 and the second casing 16 are fastened by a plurality of bolts B1. Thus, the first casing 14 and the second casing 16 of the casing 12 support the motor body 21.

[0021] The input shaft 20 extends outside the vehicle through the outer wall of the second casing 16. The tip of the input shaft 20 and the input gear 22 are covered by the third casing 18 from the outside of the vehicle. A bearing 11 is provided between the tip of the input shaft 20 and the third casing 18. The second casing 16 and the third casing 18 are fastened by a plurality of bolts B1. Thus, the second casing 16 and the third casing 18 support the input shaft 20.

[0022] The output gear 32 is located between the second casing 16 and the third casing 18. A pair of bearings 11 are provided between the output gear 32 and each of the casings 16, 18. The output shaft 30 extends outside the vehicle through the outer wall of the third casing 18. A disk rotor 34 is provided at the tip of the output shaft 30. The disk rotor 34 has a disk shape and rotates together with the output shaft 30. A brake piston 36 is provided behind the disk rotor 34 (i.e., above the paper in FIG. 2). The brake piston 36 stops the rotation of the output shaft 30 by sandwiching the disk rotor 34.

[0023] The tip of the output shaft 30 is covered by the wheel 5 from the outside of the vehicle. That is, the output shaft 30 is connected to the rear wheel 6R. Thus, the second casing 16 and the third casing 18 support the output shaft 30. In a modified example, the structure of the casing 12 is not limited to a structure divided into each of the casings 14, 16, 18, and an integral structure may be adopted.

[0024] As shown in Figures 1 and 2, the output shaft 30 is located in front of the input shaft 20. That is, the output shaft 30 is offset radially from the input shaft 20. Therefore, as shown in Figure 1, for example, when the motor body 21 applies a torque target value Tt to the input shaft 20, causing the input shaft 20 to rotate in the direction of arrow F1, the output shaft 30, which is offset from the input shaft 20, rotates in the direction of arrow F2. At this time, a casing torque Tc is applied to the casing 12 supporting the output shaft 30, which is in the opposite direction to the torque target value Tt.

[0025] The casing torque Tc causes the casing 12 to vibrate. Here, if R1 is the number of teeth of the output gear 32, R2 is the number of teeth of the input gear 22, Isum is the moment of inertia applied to the entire casing 12, and dω [rad] is the rate of change of rotation of the input shaft 20 over time, then the estimated value of the casing torque Tc is calculated based on the following equation (1).

[0026] Tc=((R1-R2) / R2)×(Isum×dω-Tt)···(1)

[0027] Furthermore, if the moment of inertia of the input shaft 20 is Ishaft1, the moment of inertia of the output shaft 30 is Ishaft2, the reduction ratio of the output gear 32 is R1 / R2, and the moment of inertia of the motor body 21 is Imot, then the moment of inertia Isum is calculated based on the following equation (2).

[0028] Isum = Ishaft² ÷ (R1 / R2) 2 +Ishaft1+Imot···(2)

[0029] Furthermore, the time rate of change dω [rad] is calculated by multiplying the change Δω per unit time Δt of the angular velocity ω [rad] calculated from the rotational speed [rpm] of the input shaft 20 by Π / 30. In other words, the time rate of change dω is calculated based on the following equation (3).

[0030] dω = Δω / Δt × Π / 30···(3)

[0031] Vibrations from the casing 12 can be transmitted into the cabin of the electric vehicle 100, potentially generating noise inside the cabin. Furthermore, as mentioned earlier, in the electric vehicle 100 of this embodiment, the casing 12 of the in-wheel motor 10 is directly connected to the body of the electric vehicle 100 via the trailing arm 4. In other words, there is no member interposed between the casing 12 of the in-wheel motor 10 and the body of the electric vehicle 100 to reduce the vibration of the casing 12. As a result, vibrations from the casing 12 generate relatively loud noise inside the cabin of the electric vehicle 100.

[0032] Furthermore, for example, when the rear wheel 6R goes over a bump, the rotational speed of the input shaft 20 changes significantly. As a result, the aforementioned rate of change over time dω increases, and therefore the casing torque Tc also increases. In other words, as the rate of change over time dω increases, the noise inside the electric vehicle 100 also increases.

[0033] The inventors have discovered that noise inside the electric vehicle 100 can be reduced by adjusting the torque target value in consideration of the casing torque Tc described above. Furthermore, they have discovered that an estimated value of the adjustment torque Ta to be added to adjust the torque target value can be calculated based on the following equation (4) using the number of teeth R1 and R2 described above, the moment of inertia Isum, and the rate of change over time dω.

[0034] Ta=((R1+R2) / R1)×Isum×dω···(4)

[0035] The control device 40 has pre-stored the number of teeth R1 and R2, the moment of inertia Ishaft1, Ishaft2, and Imot, and the equations (1) to (4) described above. These values ​​are physical quantities determined according to, for example, the thickness, diameter, and mass of the input shaft 20 and output shaft 30 of the in-wheel motor 10, and the shape, size, and mass of the motor body 21. The control device 40 reduces the casing torque Tc by adding the adjustment torque Ta to the torque target value, thereby suppressing the generation of noise inside the electric vehicle 100. Hereinafter, the pre-stored number of teeth R1 and R2, and the moment of inertia Ishaft1, Ishaft2, and Imot may be referred to as the respective physical properties.

[0036] Referring to Figure 3, the torque target value adjustment process performed by the control device 40 will be described. The control device 40 continuously performs the process shown in Figure 3 while the power to the electric vehicle 100 is turned on.

[0037] In S10, the control device 40 acquires the detected value of the input shaft 20 from the resolver 29 at predetermined intervals. The control device 40 calculates the angular velocity ω of the rotational motion of the input shaft 20 from the rotational speed of the input shaft 20.

[0038] Next, in S12, the control device 40 calculates the time rate of change dω based on the difference between the angular velocity ω calculated in S10 and the previous angular velocity ω calculated from the rotational speed obtained from the resolver 29 in the previous session, and the above-mentioned equation (3).

[0039] Furthermore, in S14, the control device 40 calculates an estimated value of the casing torque Tc based on each physical property value, the time rate of change dω calculated in S12, and the above-mentioned equation (1).

[0040] Furthermore, in S16, the control device 40 calculates an estimated value of the adjustment torque Ta based on the time rate of change dω calculated in S12, each physical property value, and the above-mentioned equation (4).

[0041] In S20, the control device 40 compares the time rate of change dω calculated in S12 with the first threshold Th1. Here, the first threshold Th1 is the time rate of change value that is estimated to generate a large amount of noise inside the electric vehicle 100. The first threshold Th1 is a value set according to the size of the electric vehicle 100, the outer diameter of the rear wheel 6R, etc., and is stored in advance by the control device 40. If the time rate of change dω is smaller than the first threshold Th1 (NO in S20), the time rate of change dω calculated in S12 does not generate enough noise inside the electric vehicle 100 to cause discomfort to the user. In this case, the control device 40 returns to the process of S10 and obtains a new detection value from the resolver 29 again. On the other hand, if the time rate of change dω is larger than the first threshold Th1 (YES in S20), noise that may cause discomfort to the user may be generated inside the electric vehicle 100, so the control device 40 proceeds to the process of S30.

[0042] In S30, the control device 40 compares the estimated value of the casing torque Tc calculated in S14 with the second threshold Th2. Here, the second threshold Th2 is the value of the casing torque Tc that is estimated to generate a large amount of noise inside the electric vehicle 100. The second threshold Th2 is a value set according to the size of the motor body 21, the size of the electric vehicle 100, the outer diameter of the rear wheel 6R, etc., and is stored in advance by the control device 40. If the estimated value of the casing torque Tc is smaller than the second threshold Th2 (NO in S30), the estimated value of the casing torque Tc calculated in S14 does not generate enough noise inside the electric vehicle 100 to cause discomfort to the user, so the control device 40 returns to the process of S10. On the other hand, if the estimated value of the casing torque Tc is larger than the second threshold Th2 (YES in S30), noise that may cause discomfort to the user may be generated inside the electric vehicle 100, so the control device 40 proceeds to the process of S40.

[0043] In S40, the control device 40 calculates a new torque target value Tt by adding the adjustment torque Ta calculated in S16 to the torque target value Tt calculated from the amount of depression of the accelerator pedal. This reduces the value of the casing torque Tc. The control device 40 controls the in-wheel motor 10 based on the new torque target value Tt. As a result, the control device 40 can reduce the casing torque Tc, for example, when the rear wheel 6R goes over a step and the rate of change over time dω exceeds the first threshold Th1. Consequently, the rate of change over time dω can be reduced by the new torque target value Tt. In this way, the control device 40 adjusts the torque target value Tt.

[0044] When the control device 40 finishes processing in S40, it returns to processing in S10 and obtains a new detected value from the resolver 29. The control device 40 repeats processing in S40 until the time rate of change dω becomes smaller than the first threshold Th1 (NO in S20) or the estimated value of the casing torque Tc becomes smaller than the second threshold Th2 (NO in S30).

[0045] Referring to Figure 4, the changes over time of the rotational speed N of the input shaft 20, the target torque Tt, the amplitude V of the casing 12, and the amplitude A of the interior noise of the electric vehicle 100 will be explained. In Figure 4, the graphs of each value when the torque adjustment process in Figure 3 is performed are shown with solid lines, and the graphs of each value when the torque adjustment process is not performed, i.e., in the conventional technology, are shown with dashed lines. In the graphs shown in Figures 4(A) to 4(D), the horizontal axis represents time. In addition, the timing T1 shown on the horizontal axis of each graph indicates the timing when the rear wheel 6R overcomes the step.

[0046] As shown in Figure 4(A), when the rear wheel 6R crosses a step at timing T1, the rotational motion of the rear wheel 6R is hindered by the step, causing the rotational speed N of the input shaft 20 to increase or decrease around a predetermined value N1. Here, as shown in Figure 4(B), conventionally, even when the rear wheel 6R crosses a step (i.e., even when the rate of change over time dω is greater than the first threshold Th1), the torque target value Tt does not change. Therefore, as shown in Figure 4(A), conventionally, the input shaft 20 rotates with a constant torque target value Tt, and the rotational speed N of the input shaft 20 changes significantly relative to the predetermined value N1 due to the disturbance of the step.

[0047] As a result, as shown in Figure 4(C), the amplitude V of the casing 12 increases after timing T1. Consequently, as shown in Figure 4(D), the amplitude A of the interior noise of the electric vehicle 100 also increases. In other words, the noise inside the electric vehicle 100 increases.

[0048] In contrast, as shown in Figure 4(B), the control device 40 of the electric vehicle 100 according to this specification adds an adjustment torque Ta to the torque target value Tt, calculated based on the above-described equation (4), in the direction of canceling out the amplitude V of the casing 12 shown in Figure 4(C). That is, the control device 40 adjusts the torque target value Tt to reduce the casing torque Tc when the rate of change over time dω is greater than the first threshold Th1 (YES at S20). As a result, as shown in Figure 4(A), the rate of change over time of the rotational speed N also decreases. This reduces the amplitude V of the casing 12. As shown in Figure 4(C), the torque target value adjustment process reduces the amplitude V of the casing 12 after timing T1 compared to the conventional method. As a result, as shown in Figure 4(D), the amplitude A of the interior noise of the electric vehicle 100 also decreases compared to the conventional method. Thus, according to the electric vehicle 100 disclosed herein, when the rate of change over time dω is greater than the first threshold Th1 (YES in S20), the vibration of the casing 12 can be reduced by adjusting the torque target value Tt to reduce the rate of change over time dω. As a result, the noise inside the electric vehicle 100 can be reduced. In this embodiment, the input shaft 20 is an example of a "first rotating shaft", and the output shaft 30 is an example of a "second rotating shaft".

[0049] (Second example) Next, the electric vehicle 100 of the second embodiment will be described. The electric vehicle 100 of the second embodiment has the same configuration as the electric vehicle 100 of the first embodiment. However, the control device 40 of the electric vehicle 100 of the second embodiment performs a different torque target value adjustment process than the control device 40 of the first embodiment. The torque target value adjustment process performed by the control device 40 of the second embodiment will be described below with reference to Figures 5 and 6. In S110 to S112, the same process as S10 to S12 shown in Figure 3 is performed. Also, in S120, the same process as S20 shown in Figure 3 is performed.

[0050] In the second embodiment, if the time rate of change dω is greater than the first threshold Th1 (YES in S120), the control device 40 sets the detected value obtained from the resolver 29 immediately before the time rate of change dω becomes greater than the first threshold Th1 as the target rotational speed Nt in S122.

[0051] In S124, the control device 40 compares the target rotational speed Nt set in S122 with the latest detected value obtained from the resolver 29 and calculates the rotational speed deviation. The rotational speed deviation is the difference between the target rotational speed Nt and the latest rotational speed.

[0052] In S130, the control device 40 compares the rotational speed deviation calculated in S124 with the third threshold Th3. Here, the third threshold Th3 is the value of rotational speed deviation that is estimated to generate a large amount of noise inside the electric vehicle 100. The third threshold Th3 is a value set according to the size of the motor body 21, the size of the electric vehicle 100, the outer diameter of the rear wheel 6R, etc., and is stored in advance by the control device 40. If the rotational speed deviation is smaller than the third threshold Th3 (NO in S130), the current rotational speed deviation will not generate enough noise inside the electric vehicle 100 to cause discomfort to the user, so the control device 40 returns to the process in S110. On the other hand, if the rotational speed deviation is larger than the third threshold Th3 (NO in S130), noise that may cause discomfort to the user may be generated inside the electric vehicle 100, so the control device 40 proceeds to the process in S140.

[0053] In S140, the control device 40 adjusts the torque target value Tt so that the rotational speed of the input shaft 20 approaches the target rotational speed Nt. That is, the control device 40 feedback-controls the torque target value Tt based on the target rotational speed Nt. In other words, the control device 40 of the second embodiment adjusts the torque target value Tt so that it approaches the normal rotational speed (i.e., the target rotational speed Nt) just before the time rate of change dω exceeds the first threshold (i.e., before the rear wheel 6R goes over the step).

[0054] Therefore, as shown in Figure 6(A), the rotational speed N approaches the target rotational speed Nt compared to the conventional method. As a result, as shown in Figure 6(B), the target torque value Tt changes in a way that cancels out the amplitude V of the casing 12. Consequently, the amplitude V of the casing 12 becomes smaller, and the amplitude A of the interior noise of the electric vehicle 100 becomes smaller compared to the conventional method. In the electric vehicle 100 of this embodiment, the detected value obtained from the resolver 29 just before the time rate of change dω becomes greater than the first threshold Th1 is set as the target rotational speed Nt. Furthermore, the electric vehicle 100 performs feedback control to adjust the target torque value Tt so that the rotational speed of the input shaft 20 approaches the target rotational speed Nt. This makes it possible to reduce the interior noise of the electric vehicle 100 with relatively simple control.

[0055] The specific examples of the technology disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. Modifications of the above embodiments are listed below.

[0056] (Modification 1) The process in S30 of Figure 3 can be omitted. In that case, the control device 40 does not need to calculate the casing torque Tc in S14.

[0057] (Modified example 2) The control device 40 does not need to calculate the casing torque Tc using the above-described formula (1). In that case, for example, the control device 40 may calculate the casing torque Tc based on the value detected by a torque sensor provided on the casing 12.

[0058] (Modification 3) In addition to the torque target value adjustment process of the first embodiment, the control device 40 may also perform the torque target value adjustment process of the second embodiment. In this case, the control device 40 may, for example, control the rotational speed of the input shaft 20 based on the torque target value Tt adjusted in S40 of Figure 3, and then perform the torque target value adjustment process of Figure 4 to perform feedback control based on the target rotational speed Nt.

[0059] (Modification 4) In the embodiment described above, the time rate of change dω of the input shaft 20 is calculated based on the value detected by the resolver 29. In this modification, the control device 40 may calculate the time rate of change dω using, for example, the rotational speed of the rear wheel 6R calculated based on the travel speed of the electric vehicle 100. In this modification, the speedometer that detects the travel speed of the electric vehicle 100 is an example of a "rotational speed sensor".

[0060] (Modification 5) In the first embodiment described above, the control device 40 calculates the casing torque Tc and the adjustment torque Ta in the torque target value adjustment process shown in Figure 3, before comparing the time rate of change dω with the first threshold Th1 in S20. In the modification, the control device 40 may calculate the casing torque Tc and the adjustment torque Ta after S20.

[0061] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0062] 2: Rear suspension, 4: Trailing arm, 5: Wheel, 6R: Rear wheel, 8: Wheel, 9: Tire, 10: In-wheel motor, 11: Bearing, 12: Casing, 14: First casing, 16: Second casing, 18: Third casing, 20: Input shaft, 21: Motor body, 22: Input gear, 24: Rotor, 25: Rotor core, 26: Stator coil, 27: Stator core, 29: Resolver, 30: Output shaft, 32: Output gear, 34: Disc rotor, 36: Brake piston, 40: Control device, 100: Electric vehicle

Claims

1. Wheels and, An in-wheel motor that drives the aforementioned wheel, A rotation speed sensor for detecting the rotation speed of the in-wheel motor, A control device that controls the in-wheel motor based on the torque target value of the in-wheel motor, Equipped with, The aforementioned in-wheel motor is The motor body and A first rotating shaft driven by the motor body, A second rotation axis is offset with respect to the first rotation axis and connected to the wheel, A torque transmission mechanism that transmits torque between the first rotating shaft and the second rotating shaft, A casing that houses the motor body and the torque transmission mechanism, and supports the first and second rotating shafts, Equipped with, The control device is When the time rate of change of the value detected by the rotation speed sensor exceeds a predetermined first threshold, the torque target value can be adjusted so that the time rate of change becomes smaller. Based on the torque target value, the rate of change over time, and a pre-stored calculation formula, an estimated value of the casing torque applied to the casing is calculated. When the rate of change over time exceeds the predetermined first threshold and the casing torque exceeds the second threshold, the torque target value is adjusted. vehicle.

2. The vehicle according to claim 1, wherein the calculation formula is based on the moment of inertia of the first rotating shaft, the moment of inertia of the second rotating shaft, the moment of inertia of the motor body, and the reduction ratio in the torque transmission mechanism.

3. The vehicle according to claim 1, wherein the control device sets the value detected by the rotation speed sensor immediately before the time rate of change exceeds the first threshold as the target rotation speed, and adjusts the torque target value based on the deviation when the deviation between the value detected by the rotation speed sensor and the target rotation speed exceeds a third threshold.

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