JP2021126030A - Electric vehicle drive - Google Patents

Abstract

An object of the present invention is to provide a drive device for an electric vehicle that can avoid a locked state of a motor even when the electric vehicle is in a locked state. [Solution] A first motor M1, a second motor M2, a planetary gear mechanism 20 that outputs a driving force by merging the outputs of the first motor M1 and the second motor M2, and a planetary gear mechanism 20 that outputs a driving force by combining the outputs of the first motor M1 and the second motor M2; A drive device 10 for an electric vehicle includes a control unit 50 that controls the rotation speed of each motor M2, and the control unit 50 controls the first motor M1 and the second motor M1 when the electric vehicle is in a locked state. Rotate motor M2. [Selection diagram] Figure 1

Description

The present invention relates to a drive device for an electric vehicle, and more particularly to a drive device having two motors.

Electric vehicles with two motors are known. Patent Document 1 discloses a drive device for an electric vehicle having a first motor, a second motor, and a planetary gear mechanism that combines the outputs of the first motor and the second motor to output a driving force. ..

The electric vehicle may be in a locked state such that the accelerator pedal is depressed but cannot move due to an obstacle or the like, or the vehicle is stopped by depressing the accelerator pedal so as not to slide down on an uphill slope. When the electric vehicle is locked, the motor is also locked.

Japanese Unexamined Patent Publication No. 2018-100709

In the locked state of the motor, the current may be concentrated in a specific phase according to the position of the rotor of the motor, and the temperature of the switching element of the inverter of the phase may rise. Therefore, it is desired that the locked state of the motor can be avoided even when the electric vehicle is locked.

An object of the present invention is to provide a drive device for an electric vehicle capable of avoiding the locked state of the motor even when the electric vehicle is locked.

One aspect of the present invention is a planetary gear mechanism that merges the outputs of the first motor, the second motor, the first motor and the second motor to output a driving force, and at least the first motor and the second motor. It is a drive device of an electric vehicle having a control unit for controlling each rotation speed, and the control unit rotates a first motor and a second motor when the electric vehicle is locked.

Further, it is preferable that the control unit rotates the first motor in the direction opposite to the rotation direction of the second motor when the electric vehicle is locked.

Further, it is preferable that the control unit determines the rotation speed of the first motor by multiplying the rotation speed of the second motor by a coefficient including the reduction ratio of the planetary gear mechanism when the electric vehicle is locked. ..

ここで、ω１は第１モータの回転数（０の近傍ではない任意の値）、ω２は第２モータの回転数（０の近傍ではない任意の値）、Ｇ１は第１モータの減速機構の減速比、Ｇ２は第２モータの減速機構の減速比、ρは遊星歯車機構の減速比である。 Further, the control unit determines the rotation speed of the first motor and the rotation speed of the second motor that satisfy the following equations when the electric vehicle is locked.

Here, ω1 is the rotation speed of the first motor (arbitrary value not near 0), ω2 is the rotation speed of the second motor (arbitrary value not near 0), and G1 is the reduction mechanism of the first motor. The reduction ratio, G2 is the reduction ratio of the reduction mechanism of the second motor, and ρ is the reduction ratio of the planetary gear mechanism.

Further, the planetary gear mechanism includes a first sun gear which is a first input element to which the first motor is connected, a second sun gear which is a second input element to which the second motor is connected, and a planetary carrier which is an output element. It is preferred to include an inner planetary pinion that is rotatably supported by the planetary carrier and meshes with the first sun gear, and an outer planetary pinion that is rotatably supported by the planetary carrier and meshes with the second sun gear and the inner planetary pinion. ..

According to the present invention, it is possible to avoid the locked state of the motor even when the electric vehicle is locked.

It is a schematic diagram which shows the drive device which is an example of an embodiment. It is a figure which shows the flow of power in the 1st running mode of the drive device which is an example of an embodiment. It is a figure which shows the flow of power in the 2nd traveling mode of the drive device which is an example of an embodiment. It is a block diagram which shows the control part of the drive device which is an example of an embodiment. It is a flow chart which shows the flow of the motor lock avoidance control.

Hereinafter, an example of the embodiment of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present disclosure, and can be appropriately changed according to the intended use, purpose, specifications, and the like.

The drive device 10 will be described with reference to FIG. FIG. 1 is a schematic view showing the configuration of the drive device 10.

The drive device 10 which is an example of the present embodiment is a device for driving an electric vehicle, and is driven by merging the outputs of the first motor M1, the second motor M2, the first motor M1 and the second motor M2. It has a planetary gear mechanism 20 that outputs force, and a control unit 50 (see FIG. 4) that controls at least the rotation speeds of the first motor M1 and the second motor M2. The first motor M1 and the second motor M2 are connected to different input elements of the planetary gear mechanism 20, respectively. The output elements of the planetary gear mechanism 20 are connected to the left and right drive wheels 11 via a final reduction mechanism 40 including a differential device.

The planetary gear mechanism 20 has two input elements, a first sun gear 21 to which the first motor M1 is connected and a second sun gear 22 to which the second motor M2 is connected. The first sun gear 21 meshes with a plurality of inner planetary pinions (hereinafter, referred to as inner pinions 23) rotatably supported by a carrier 24 described later. The second sun gear 22 meshes with a plurality of outer planetary pinions (hereinafter referred to as outer pinions 25) rotatably supported by a planetary carrier (hereinafter referred to as carrier 24). Each inner pinion 23 also meshes with one outer pinion 25.

In the planetary gear mechanism 20, the first sun gear 21, the second sun gear 22, and the carrier 24 are rotatable around a common axis. The carrier 24 has an output gear 26 as an output element. The output gear 26 constitutes the final reduction gear pair 42 together with the driven gear 41 that rotates integrally with the differential device. The planetary gear mechanism 20 is a composite type including a first planetary gear train 27 including a first sun gear 21, an outer pinion 25, and an inner pinion 23, and a second planetary gear train 28 including a second sun gear 22 and an outer pinion 25. It is a planetary gear mechanism. The first planetary gear train 27 is a double pinion type planetary gear train, and the second planetary gear train 28 is a single pinion type planetary gear train.

The first sun gear 21 is fixed to the first input shaft 31. The first input shaft 31 is connected to the first motor shaft 33, which is the output shaft of the first motor M1, via the first input gear pair 32. The first motor shaft 33 itself may be used as the first input shaft 31. The second sun gear 22 is fixed to the second input shaft 35. The second input shaft 35 is connected to the second motor shaft 37, which is the output shaft of the second motor M2, via the second input gear pair 36. The second motor shaft 37 itself may be used as the second input shaft 35.

The first input gear pair 32 represents a transmission mechanism between the first motor shaft 33 and the first input shaft 31, and the second input gear pair 36 represents the second motor shaft 37 and the second input shaft 35. It represents a transmission mechanism between gears, and may be a gear train having another configuration, for example, three or more gears. Instead of the first input gear pair 32 and the second input gear pair 36, another speed conversion mechanism, for example, a chain and a sprocket may be included as a transmission mechanism.

The planetary gear mechanism 20 of the present embodiment is a mechanism having three elements and two degrees of freedom, and when the rotation speed of two of the three elements is determined, the rotation speed of the remaining one element is uniquely determined. For example, once the rotation speeds of the first sun gear 21 and the second sun gear 22 are determined, the rotation speed of the carrier 24 is determined accordingly.

The transmission system from the second motor M2 to the second sun gear 22 is provided with a clutch element that allows the second sun gear 22 to rotate in the rotational direction when the electric vehicle moves forward and prevents the second sun gear 22 from rotating in the reverse direction. The clutch element is, for example, a one-way clutch 45 provided on the second input shaft 35.

The drive device 10 has a first traveling mode in which the electric vehicle is driven only by the output of the first motor M1 and a second traveling mode in which the electric vehicle is driven by the outputs of both the first motor M1 and the second motor M2. It has two driving modes. The first travel mode is used under low speed or low load conditions and the second travel mode is used under high speed or high load conditions.

The first traveling mode will be described with reference to FIG. FIG. 2 is a diagram showing a flow of power of the drive device 10 in the first traveling mode.

In the first traveling mode, the output of the first motor M1 is transmitted to the first input shaft 31 and the first sun gear 21 via the first input gear pair 32 to operate the first planetary gear train 27. With the operation of the first planetary gear train 27, torque is also transmitted to the second planetary gear train 28 to try to rotate the second sun gear 22, but the rotation is blocked by the one-way clutch 45 when the electric vehicle is moving forward. NS.

As a result, the rotation speeds of two of the three elements (first sun gear 21 and second sun gear 22) are determined, and the rotation speed of the remaining one element (carrier 24) is determined. The rotation of the carrier 24 is transmitted to the drive wheels 11 via the final reduction mechanism 40. On the other hand, when the vehicle is moving backward, the second sun gear 22 cannot be fixed by the one-way clutch 45, so the second motor M2 is operated to fix the second sun gear 22 or drive it at an extremely low speed.

The second traveling mode will be described with reference to FIG. FIG. 3 is a diagram showing the flow of power of the drive device 10 in the second traveling mode.

In the second traveling mode, the output of the first motor M1 is transmitted to the first input shaft 31 and the first sun gear 21 via the first input gear pair 32. On the other hand, the output of the second motor M2 is transmitted to the second input shaft 35 and the second sun gear 22 via the second input gear pair 36. Since the rotation speeds of the two elements (first sun gear 21 and second sun gear 22) are determined, the rotation speed of the remaining one element (carrier 24) is determined.

Further, while the electric vehicle is traveling at a predetermined speed, the rotation speed of the carrier 24 is determined according to the speed of the electric vehicle. The rotation speeds of the first motor M1 and the second motor M2 can be changed although they are mutually restricted. Therefore, the power consumption of the drive device 10 can be reduced by operating the first motor M1 and the second motor M2 at efficient rotation speeds. Since the second motor M2 is prevented from rotating in the reverse direction by the one-way clutch 45, the second traveling mode cannot be used when moving backward.

The control unit 50 will be described with reference to FIG. FIG. 4 is a block diagram showing the control unit 50.

The control unit 50 controls the outputs of the first motor M1 and the second motor M2. The outputs of the first motor M1 and the second motor M2 include at least the rotation speeds of the first motor M1 and the second motor M2, respectively. The control unit 50 is connected to the first motor M1, the second motor M2, the accelerator opening sensor 55 of the electric vehicle, and the vehicle speed sensor 56 of the electric vehicle.

The control unit 50 is equipped with a CPU as an arithmetic processing unit that executes control, and a ROM, RAM, and a hard disk drive (HDD) as storage devices connected to the CPU. Further, the control unit 50 controls the required driving force calculation unit 51 that calculates the driving force required for the electric vehicle, and the outputs of the first motor M1 and the second motor M2 in the case of normal operation of the electric vehicle during normal operation. It has a control unit 52 and a locked control unit 53 that controls the outputs of the first motor M1 and the second motor M2 when the electric vehicle is in the locked state.

The required driving force calculation unit 51 determines the driving force required for the driving device 10 of the electric vehicle based on the accelerator opening of the electric vehicle acquired by the accelerator opening sensor 55 and the vehicle speed acquired by the vehicle speed sensor 56 of the electric vehicle. Is calculated. When the electric vehicle is in normal operation, the normal time control unit 52 determines the command values of the first motor M1 and the second motor M2 based on the required driving force calculated by the required driving force calculation unit 51, and determines the command value. The command value is transmitted to the first motor M1 and the second motor M2, respectively. The command values of the first motor M1 and the second motor M2 include at least the command values of the rotation speeds and torques of the first motor M1 and the second motor M2, respectively.

The lock control unit 53 determines the command values of the first motor M1 and the second motor M2 when the drive device 10 of the electric vehicle is locked, and transmits the command values to the first motor M1 and the second motor M2. do. The command values of the first motor M1 and the second motor M2 include at least the command values of the rotation speeds of the first motor M1 and the second motor M2. The locked state of the electric vehicle is, for example, a state in which the accelerator pedal is depressed but cannot move due to an obstacle or the like, or a state in which the vehicle is stopped by depressing the accelerator pedal so as not to slide down on an uphill slope.

The motor lock avoidance control S10 will be described with reference to FIG. FIG. 5 is a flow showing the flow of the motor lock avoidance control S10.

In the motor lock avoidance control S10, even when the electric vehicle is in the locked state, the first motor M1 and the second motor M2 are locked by rotating the first motor M1 and the second motor M2 by the control unit 50, respectively. It is a control that avoids becoming a state. According to the motor lock avoidance control S10, it is possible to prevent the first motor M1 and the second motor M2 from being in the locked state even when the electric vehicle is in the locked state.

In step S11, the normal time control unit 52 determines the traveling mode of the drive device 10, determines the command values of the first motor M1 and the second motor M2, and sets the command values to the first motor M1 and the second motor M2. Send to each. The command values of the first motor M1 and the second motor M2 include at least the command values of the rotation speeds and torques of the first motor M1 and the second motor M2, respectively.

In step S12, the normal time control unit 52 confirms whether or not the electric vehicle is in the locked state. Specifically, for example, when the command rotation speed of the first motor M1 or the second motor M2 is equal to or less than a predetermined rotation speed and the command torque is equal to or more than a predetermined torque value for a predetermined time or longer, the electric vehicle Determined to be in the locked state. Further, for example, when the cooling water temperature of the inverters of the first motor M1 or the second motor M2 is equal to or higher than a predetermined temperature, it may be determined that the electric vehicle is in the locked state. If the electric vehicle is in the locked state, the process proceeds to step S13, and if the electric vehicle is not in the locked state, the motor lock avoidance control S10 is terminated.

In step S13, the locked time control unit 53 confirms whether or not the current traveling mode is the first traveling mode. If the current running mode is the first running mode, the process proceeds to step S14, and the running mode is changed to the second running mode.

ここで、上述したようにαは、０の近傍ではない任意の正値とする。なお、正値とは、電動車両が前進する場合のモータの回転数の方向を正としたときの回転数である。また、本実施形態の駆動装置１０では、ワンウェイクラッチ４５により後進方向の回転が阻止されているためαを０の近傍ではない任意の正値としているものの、ワンウェイクラッチ４５が設けられない駆動装置では、αを０の近傍ではない任意値としてもよい。 In step S15, the locked time control unit 53 determines the rotation speed of the rotation speed ω1 of the first motor M1 as the value shown in the equation (1), and sets the rotation speed ω2 of the second motor M2 to α (not in the vicinity of 0). It is determined to be an arbitrary positive value) and transmitted to the first motor M1 and the second motor M2.

Here, as described above, α is an arbitrary positive value that is not in the vicinity of 0. The positive value is the number of rotations when the direction of the number of rotations of the motor when the electric vehicle moves forward is positive. Further, in the drive device 10 of the present embodiment, since the rotation in the reverse direction is blocked by the one-way clutch 45, α is set to an arbitrary positive value that is not in the vicinity of 0, but in the drive device in which the one-way clutch 45 is not provided. , Α may be an arbitrary value that is not in the vicinity of 0.

ここで、車速：Ｖ［ｋｍ／ｈ］、駆動輪１１の半径：Ｒｔｉｒｅ［ｍ］、最終減速機構４０の減速比：Ｇｆ、第１モータＭ１の減速機構の減速比：Ｇ１、第２モータＭ２の減速機構の減速比：Ｇ２、遊星歯車機構２０の減速比：ρとする。なお、第１モータＭ１の減速機構の減速比とは、第１モータＭ１から第１サンギア２１までの減速比である。第２モータＭ２の減速機構の減速比とは、第２モータＭ２から第２サンギア２２までの減速比である。遊星歯車機構２０の減速比とは、第１サンギア２１又は第２サンギア２２から出力ギア２６までの減速比である。 Hereinafter, a method for calculating the rotation speed ω1 according to the equation (1) will be described.
In the drive device 10, the relationship between the vehicle speed V, the rotation speed ω1 of the first motor M1 and the rotation speed ω2 of the second motor M2 is given by the following equation (2).

Here, the vehicle speed: V [km / h], the radius of the drive wheels 11: Rtile [m], the reduction ratio of the final reduction mechanism 40: Gf, the reduction ratio of the reduction mechanism of the first motor M1: G1, the second motor M2. The reduction ratio of the reduction mechanism: G2 and the reduction ratio of the planetary gear mechanism 20: ρ. The reduction ratio of the reduction mechanism of the first motor M1 is the reduction ratio from the first motor M1 to the first sun gear 21. The reduction ratio of the reduction mechanism of the second motor M2 is the reduction ratio from the second motor M2 to the second sun gear 22. The reduction ratio of the planetary gear mechanism 20 is a reduction ratio from the first sun gear 21 or the second sun gear 22 to the output gear 26.

第１モータＭ１及び第２モータＭ２をそれぞれ回転させるために、式（３）を満たすべく、ω２の指令値として０ｒｐｍ近傍ではない正値を決定し、ω１の指令値として式（３）を満たす値、すなわち上述した式（１）を決定すればよい。 In the formula (2), when the electric vehicle is in the locked state, V = 0 km / h. At this time, the rotation speed ω1 and the rotation speed ω2 expand the equation (2) to establish the following relationship.

In order to rotate the first motor M1 and the second motor M2, respectively, in order to satisfy the equation (3), a positive value other than around 0 rpm is determined as the command value of ω2, and the equation (3) is satisfied as the command value of ω1. The value, that is, the above-mentioned equation (1) may be determined.

The effect of the drive device 10 which is an example of the present embodiment will be described. According to the drive device 10, even when the electric vehicle is locked by the motor lock avoidance control S10, the first motor M1 and the second motor M2 are rotated by rotating the first motor M1 and the second motor M2, respectively. Can be prevented from becoming locked. As a result, it is possible to prevent the current from concentrating in a specific phase according to the position of the rotor of the first motor M1 and the second motor M2, and to prevent the temperature of the switching element of the inverter of the phase from rising.

It should be noted that the present invention is not limited to the above-described embodiments and modifications thereof, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application. ..

10 drive unit, 11 drive wheels, 20 planetary gear mechanism, 21 first sun gear, 23 inner pinion, 24 carrier, 25 outer pinion, 26 output gear, 40 final reduction mechanism, 41 driven gear, 42 final reduction gear pair, 45 One-way clutch, 50 control unit, 51 required driving force calculation unit, 52 normal control unit, 53 lock control unit, 55 accelerator opening sensor, 56 vehicle speed sensor, S10 motor lock avoidance control.

Claims (5)

A first motor, a second motor, a planetary gear mechanism that merges the outputs of the first motor and the second motor to output a driving force, and at least the rotation speeds of the first motor and the second motor, respectively. A drive device for an electric vehicle having a control unit for controlling
The control unit rotates the first motor and the second motor when the electric vehicle is locked.
Drive device for electric vehicles. The drive device for an electric vehicle according to claim 1.
When the electric vehicle is locked, the control unit rotates the first motor in a direction opposite to the rotation direction of the second motor.
Drive device for electric vehicles. The drive device for an electric vehicle according to claim 2.
When the electric vehicle is locked, the control unit determines the rotation speed of the first motor by multiplying the rotation speed of the second motor by a coefficient including a reduction ratio of the planetary gear mechanism.
Drive device for electric vehicles. The drive device for an electric vehicle according to claim 3.
When the electric vehicle is locked, the control unit determines the rotation speed of the first motor and the rotation speed of the second motor that satisfy the following equations, respectively.
Drive device for electric vehicles.

Here, ω1 is the rotation speed of the first motor, ω2 is the rotation speed of the second motor, G1 is the reduction ratio of the reduction mechanism of the first motor, G2 is the reduction ratio of the reduction mechanism of the second motor, ρ. Is the reduction ratio of the planetary gear mechanism. The drive device for an electric vehicle according to any one of claims 1 to 4.
The planetary gear mechanism includes a first sun gear which is a first input element to which the first motor is connected, a second sun gear which is a second input element to which the second motor is connected, and a planetary carrier which is an output element. An inner planetary pinion that is rotatably supported by the planetary carrier and meshes with the first sun gear, and an outer planetary pinion that is rotatably supported by the planetary carrier and meshes with the inner planetary pinion. include,
Drive device for electric vehicles.

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