JP5772754B2 - Electric vehicle drive device - Google Patents

Description

  The present invention relates to a drive device for an electric vehicle, and more particularly to a drive device for an electric vehicle having a drive motor cooled by a coolant supplied by an electric pump and capable of adjusting cooling by the electric pump and noise.

  In an electric vehicle or a hybrid vehicle, the vehicle travels using the driving force of the driving motor. Since this driving motor has a large output, it generates a large amount of heat. Therefore, a cooling system that cools a driving motor of a vehicle by circulating a coolant is known. Some cooling systems of this type employ an electric pump as a pump for delivering a coolant.

  When this electric pump is driven, an operating noise is generated. This operation sound may be felt as noise for the passengers in the vehicle. Particularly when traveling at low speed, road noise, wind noise, and the like that the tire rolls on the road surface are reduced, and the quietness of the interior of the vehicle is increased, so that the operation sound of the electric pump is easily felt by the passengers as noise.

  In this connection, Patent Document 1 discloses that when the noise level of the electric pump other than the operation sound of the electric pump is equal to or greater than a predetermined threshold value, the operation sound of the electric pump is not easily recognized by the occupant as noise. A control device for an electric pump is described in which the electric pump is turned on and the electric pump is turned off at other times.

Japanese Patent Laying-Open No. 2005-201225

  In such a cooling system, when the noise other than the operation sound of the electric pump is equal to or lower than a predetermined threshold, the electric pump does not send the coolant to the drive motor. Therefore, when the noise other than the operation sound of the electric pump is equal to or lower than a predetermined threshold, the driving motor may not be sufficiently cooled.

  An electric vehicle driving apparatus according to the present invention includes an electric pump, a first driving motor cooled by a coolant supplied by the electric pump, a second driving motor, the electric pump, and the two A drive unit for an electric vehicle having a control unit for controlling a drive motor, and when the noise level in the vehicle is less than a predetermined value, the control unit Control is performed such that the rotational speed of the electric pump is reduced, the torque of the first drive motor is reduced, and the torque of the second drive motor is increased.

  The electric vehicle drive device according to the present invention further includes a secondary battery that supplies electric power to the drive motor, and the rotational speed of the electric pump is only when the charge amount of the secondary battery is equal to or greater than a predetermined amount. It is preferable to control the torques of the two drive motors.

  In the electric vehicle driving apparatus according to the present invention, it is preferable that the rotational speed of the electric pump and the torques of the two driving motors are controlled only when the required driving torque is equal to or greater than a predetermined torque.

  In the drive device for an electric vehicle according to the present invention, it is preferable that the noise is a noise in a vehicle excluding an operation sound of the electric pump.

  Moreover, in the drive device for an electric vehicle according to the present invention, the predetermined value is preferably a value based on the loudness of the operation sound of the electric pump.

  As described above, when the noise level in the vehicle is less than the predetermined value, the control unit reduces the number of rotations of the electric pump and increases the torque of the first drive motor as compared to the case where the noise level is higher than the predetermined value. The torque is reduced to limit the torque of the second drive motor. Therefore, even if the noise in the vehicle is small and the operation of the electric pump is controlled, the temperature increase of the first drive motor can be suppressed.

It is a block diagram which shows the whole structure of the vehicle of an Example. It is a figure showing the relationship between the vehicle speed of the vehicle of an Example, and the noise in a vehicle. It is a flowchart showing operation | movement of a 1st Example. It is a flowchart showing operation | movement of a 2nd Example. It is a time chart which shows an example of a change of operation of two drive motors and an electric pump when vehicles of the 2nd example run.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of an electric vehicle 10 equipped with the vehicle control device according to the embodiment will be described with reference to FIG. As shown in FIG. 1, an electric vehicle 10 includes a high voltage battery 12, inverters 14 and 16, a front motor 18, a rear motor 20, a front wheel 22, a rear wheel 24, a motor cooling device 26, and a motor control device. 28 is an electric vehicle.

  The high voltage battery 12 is a secondary battery capable of storing electric power for driving the vehicle, and supplies electric power to the inverters 14 and 16. The inverters 14 and 16 convert the DC voltage supplied from the high-voltage battery 12 into a three-phase AC voltage and supply it to the front motor 18 and the rear motor 20. The front motor 18 and the rear motor 20 are three-phase synchronous rotating electric machines that are driven by a three-phase AC voltage. The driving torque output from the front motor 18 is transmitted to the front wheels 22, and the front wheels 22 are driven. The driving torque output from the rear motor 20 is transmitted to the rear wheel 24, and the rear wheel 24 is driven. The high-voltage battery 12 is charged by electric power supplied from a commercial power source for home use or a quick charge power source for a charging stand via a charging device (not shown).

  Next, the motor cooling device 26 will be described. The motor cooling device 26 cools the temperature of the front motor 18 so as not to be overheated. The motor cooling device 26 includes an electric pump 30, a radiator 32, and a cooling pipe 34. The electric pump 30 is a pump for sending the coolant to the front motor 18. The radiator 32 exchanges heat with the outside air to cool the coolant. The cooling pipe 34 is a pipe for circulating the coolant among the front motor 18, the radiator 32, and the electric pump 30. The electric pump 30 sends out the coolant by the rotational force of the motor, and various types of pumps such as a diaphragm pump can be employed.

  The coolant sent out by the electric pump 30 is sent to the radiator 32 through the cooling pipe 34. The coolant cooled by the radiator 32 is supplied to the front motor 18 through the cooling pipe 34 to cool the front motor 18. The coolant whose temperature has increased due to heat exchange with the front motor 18 is sent again to the electric pump 30 through the cooling pipe 34.

  Next, the motor control device 28 will be described. The motor control device 28 includes a vehicle speed sensor 36, an accelerator opening sensor 38, torque detection means 40, a voltage sensor 42, a temperature sensor 44, and an ECU 46. The vehicle speed sensor 36 detects the traveling speed of the vehicle and supplies it to the ECU 46. The accelerator opening sensor 38 detects the opening (operation amount) of the accelerator pedal and supplies it to the ECU 46. The torque detection means 40 detects the drive torque output from the front motor 18 and the rear motor 20 and supplies them to the ECU 46. The torque detection means 40 is constituted by a torque sensor provided on the drive shafts of the front motor 18 and the rear motor 20, for example. Alternatively, the driving torque may be estimated based on the control amounts of the front motor 18 and the rear motor 20 supplied from the ECU 46 to the inverters 14 and 16 from the ECU 46. In this case, the ECU 46 functions as the torque detection means 40. The voltage sensor 42 detects the voltage of the high voltage battery 12 and supplies it to the ECU 46. Based on the detected voltage value, the ECU 46 estimates the charge amount of the high voltage battery 12 and estimates the state of charge (SOC) of the high voltage battery 12 based on the charge amount. The method for estimating the state of charge (SOC) of the high-voltage battery 12 is not limited to the case where the voltage sensor 42 is used. For example, the state of charge (SOC) of the high-voltage battery 12 may be estimated by measuring the discharge current using a current sensor. The temperature sensor 44 detects the temperature of the front motor 18 and supplies it to the ECU 46.

  Next, noise other than the operation sound of the electric pump 30 and the operation sound of the electric pump 30 will be described. When the front motor 18 is cooled using the motor cooling device 26 including the electric pump 30 as described above, an operation sound is generated with the operation of the electric pump 30. When noise (road noise, wind noise, etc.) other than the operation sound of the electric pump 30 in the vehicle is loud, the operation sound of the electric pump 30 is masked by other noises, so that the passenger in the vehicle operates the operation sound of the electric pump 30. Is difficult to recognize audibly. However, when the noise is low, the operation sound of the electric pump 30 is easily perceived by an occupant in the vehicle and becomes noticeable as an irritating sound. Here, the minimum value is set to a predetermined value Lb in the range of the sound pressure of the noise masked by the operation sound of the electric pump 30. In the first embodiment, the sound pressure is used as the noise level, but the present invention is not limited to this. For example, a value calculated by weighting a specific frequency that is harsh to the passenger may be used. In the first embodiment, the predetermined value is determined depending on whether or not the operation sound of the electric pump 30 is masked, but the method of determining the predetermined value is not limited to this. For example, when the quietness in the vehicle is not so required, a value smaller than the above minimum value may be set as the predetermined value Lb. Conversely, when high silence is required, a value larger than the above minimum value may be set as the predetermined value Lb.

  FIG. 2 is a diagram illustrating the relationship between the vehicle speed of the electric vehicle 10 and the sound pressure of noise. The horizontal axis represents the vehicle speed V [km / h], and the vertical axis represents the sound pressure [dB] of the noise in the vehicle. Of the noise in the vehicle, the magnitude of road noise, wind noise and the like tends to increase as the vehicle speed V increases. On the other hand, the operating sound of the electric pump 30 does not increase or decrease depending on the vehicle speed. Therefore, the magnitude of the noise combining all of the operation sound, road noise, wind noise, etc. of the electric pump 30 increases as the vehicle speed V increases as shown in FIG. Therefore, if the relationship of FIG. 2 is known by performing measurement or the like in advance, the magnitude of noise in the vehicle can be estimated from the vehicle speed V. Specifically, if the vehicle speed when the magnitude of the noise in the vehicle is the predetermined value Lb is Vb, the vehicle noise is less than the predetermined value Lb when the vehicle speed V is less than the threshold value Vb, and the vehicle speed V is the threshold value. When it is Vb or higher, it can be estimated that the noise in the vehicle is equal to or higher than the predetermined value Lb.

  Therefore, when the vehicle speed V is greater than or equal to the threshold value Vb, the ECU 46 assumes that the noise level in the vehicle is greater than or equal to the predetermined value Lb and cools the front motor 18 by the electric pump 30. By doing so, the front motor 18 is reliably cooled by the coolant, and the operation sound of the electric pump 30 is masked by other noises, so that it is difficult for the passenger to recognize the operation sound of the electric pump 30 audibly. it can. On the other hand, when the vehicle speed V is less than the threshold value Vb, it is assumed that the noise level in the vehicle is less than the predetermined value Lb, the electric pump 30 does not operate, and torque distribution for changing the torque distribution between the front motor 18 and the rear motor 20 is performed. I do. Since the electric pump 30 is not driven, the operation sound of the electric pump 30 is not generated, and the quietness in the vehicle can be ensured.

  Here, torque distribution will be described. The ECU 46 normally controls the front motor 18 and the rear motor 20 by distributing the required torque Trqd to the two drive torques Trq1 and Trq2 so that the overall efficiency of the front motor 18 and the rear motor 20 is maximized. More specifically, the ECU 46 gives the inverters 14 and 16 control commands necessary for outputting the drive torque Trq1 from the front motor 18 and the drive torque Trq2 from the rear motor 20, respectively. The required torque Trqd is calculated according to the accelerator opening detected by the accelerator opening sensor 38 and the vehicle speed detected by the vehicle speed sensor 36. Note that the ECU 46 of the first embodiment uses the front motor 18 having a larger output than the rear motor 20 in order to maximize the overall efficiency of the front motor 18 and the rear motor 20 during normal travel. Further, when excessive torque is required such as when suddenly starting, the rear motor 20 is used to assist the front motor 18.

  When performing torque distribution, the ECU 46 increases the driving torque of the rear motor 20 to output the total torque of the required torque Trqd, and decreases the driving torque of the front motor 18 to zero. If the required torque Trqd is large and the required torque Trqd cannot be output even when the rear motor 20 is set to full torque, the front motor 18 is driven with the insufficient driving torque. As a result, the driving torque of the front motor 18 can be reduced while satisfying the required torque Trqd, and thus heat generation of the front motor 18 due to driving can be suppressed. When canceling the torque distribution, the drive torque of the front motor 18 and the rear motor 20 is switched to the torque distribution that maximizes the efficiency of the entire drive device as described above.

  Next, the operation of the motor control device 28 will be described with reference to FIG. First, the ECU 46 detects the state of charge (SOC) of the high voltage battery 12 in S10, and determines the magnitude relationship between the detected state of charge (SOC) of the high voltage battery 12 and a predetermined threshold value Q%. The charge state of the high voltage battery 12 is obtained by estimating the charge capacity of the high voltage battery 12 relative to the rated battery capacity based on the discharge voltage of the high voltage battery 12 detected by the voltage sensor 42. The threshold value Q% at this time can be set to, for example, 45% as a lower limit value at which the high voltage battery 12 does not overdischarge. Of course, this value is an example and can be set to other values. When it is determined in S10 that the state of charge (SOC) of the high-voltage battery 12 is Q% or more, the vehicle speed V is detected in the subsequent S12, and the magnitude relationship between the detected vehicle speed V and the threshold value Vb is compared. When it is determined in S12 that the vehicle speed V is less than the threshold value Vb, torque distribution is performed to decrease the driving torque of the front motor 18 and increase the driving torque of the rear motor 20 in S14, and the electric pump 30 is stopped in S16. . If it is determined in S10 that the state of charge (SOC) of the high voltage battery 12 is less than Q%, or if it is determined in S12 that the vehicle speed V is equal to or higher than the threshold value Vb, torque distribution is not performed in S18, and electric power is generated in S20. The pump 30 is normally operated. The operation for determining the motor control device 28 as described above is repeated at a certain cycle. This cycle is repeatedly executed every predetermined time (for example, every 8 milliseconds).

  As described above, according to the present embodiment, the operating states of the two drive motors and the electric pump 30 are optimized according to the vehicle speed V and the state of charge (SOC) of the high-voltage battery 12. Can be switched. Specifically, the ECU 46 stops the electric pump 30 and distributes the torque if the state of charge (SOC) of the high-voltage battery 12 is Q% or more and the vehicle speed V is less than the threshold value Vb. Therefore, it is possible to suppress the temperature of the front motor 18 from exceeding the allowable temperature by torque distribution while satisfying the required torque Trqd. Moreover, since the electric pump 30 is not operated, the passenger does not recognize the operation sound of the electric pump 30, and the quietness in the electric vehicle 10 can be ensured.

  Further, the ECU 46 normally operates the electric pump 30 without performing torque distribution when the vehicle speed V is equal to or higher than the threshold value Vb even when the state of charge (SOC) of the high-voltage battery 12 is equal to or higher than Q%. Therefore, the front motor 18 can be reliably cooled by the coolant supplied from the electric pump 30, and the temperature of the front motor 18 can be suppressed from exceeding the allowable temperature. Further, since the vehicle speed V is high, the operation sound of the electric pump 30 is masked by noise such as road noise and wind noise, and it becomes difficult for the passenger to recognize the operation sound of the electric pump 30 audibly.

  In the first embodiment, the magnitude relationship between the state of charge (SOC) of the high-voltage battery 12 and the threshold value Q% is compared in S10, but the above effect can be obtained without this step. it can. When there is a step of S10 as in the first embodiment, when the state of charge (SOC) of the high voltage battery 12 is less than Q%, the electric pump 30 is normally operated without torque distribution. In addition to the effect, it is possible to obtain an effect that power consumption can be reduced and overdischarge of the high voltage battery 12 can be suppressed.

  Next, a second embodiment of the present invention will be described. In the first embodiment described above, the ECU 46 controls the electric pump 30 and the two drive motors based on the vehicle speed V of the electric vehicle 10 and the state of charge (SOC) of the high-voltage battery 12. On the other hand, in the second embodiment, the ECU 46 controls the electric pump 30 and the electric pump 30 based on the temperature of the front motor 18, the state of charge (SOC) of the high-voltage battery 12, the level of noise in the electric vehicle 10, and the required torque. Controls two drive motors. Although the overall configuration is the same as in FIG. 1, the electric pump 30 and the two drive motors are controlled according to the flowchart shown in FIG.

  Next, the operation of the motor control device 28 will be described with reference to FIG. The ECU 46 first determines whether or not the front motor 18 is in an overheated state in S22. Specifically, it is determined whether or not the temperature Tmg of the front motor 18 detected by the temperature sensor 44 is 120 ° C. or higher. In electric powered vehicle 10 of the second embodiment, its use is restricted when temperature Tmg of front motor 18 exceeds 160 ° C. Therefore, in order to prevent the use restriction of the front motor 18, 120 ° C. lower than 160 ° C. is set as the threshold temperature, but this threshold can be changed as appropriate. If it is determined in S22 that the temperature Tmg of the front motor 18 is lower than 120 ° C., torque distribution is not performed in subsequent S38, and the electric pump 30 is stopped in subsequent S40. Then, this routine ends.

  When the ECU 46 determines that the temperature Tmg of the front motor 18 is 120 ° C. or higher in S22, the ECU 46 sets the reference rotational speed N of the electric pump 30 based on the temperature Tmg of the front motor 18 in subsequent S24. The reference rotational speed N is the rotational speed of the electric pump 30 that can supply a sufficient amount of coolant to suppress overheating of the front motor 18. Specifically, when the rotation speed of the electric pump 30 is switched in multiple stages, a higher value is set as the reference rotation speed N as the temperature Tmg of the front motor 18 is higher, and a lower value is set as the reference rotation speed as Tmg is lower. Set as N. When only two driving states of the electric pump 30 can be selected, ON and OFF, the rotation speed in the ON state is set to the reference rotation speed N. When the rotation speed of the electric pump 30 can be continuously switched, a value proportional to Tmg may be set as the reference rotation speed N.

  The ECU 46 calculates the reference rotational speed N of the electric pump 30 in S24, and then determines the required torque Trqd in S26. Specifically, first, the required torque Trqd is calculated according to the accelerator opening detected by the accelerator opening sensor 38 and the vehicle speed detected by the vehicle speed sensor 36. When the required torque Trqd is compared with the threshold value Tb and it is determined that the required torque Trqd is less than Tb, torque distribution is not performed in subsequent S38, and the electric pump 30 is stopped in subsequent S40. Then, this routine ends.

  When the ECU 46 determines that the required torque Trqd is equal to or greater than Tb in S26, the ECU 46 determines the state of charge (SOC) of the high-voltage battery 12 in subsequent S28. If it is determined that the state of charge (SOC) of the high-voltage battery 12 is less than the threshold value Q%, torque distribution is not performed in subsequent S42, and the electric pump 30 is operated at the reference rotational speed N in subsequent S44. Then, this routine ends.

  When the ECU 46 compares the state of charge (SOC) of the high-voltage battery 12 with the threshold value Q% in S28 and determines that the state of charge (SOC) of the high-voltage battery 12 is equal to or greater than the threshold value Q%, in S30, the ECU 46 continues. Determine the speed of the vehicle. Specifically, the vehicle speed V detected by the vehicle speed sensor 36 is compared with the threshold value Vb. If it is determined that the vehicle speed V is equal to or higher than the threshold value Vb, torque distribution is not performed in subsequent S42, and the electric pump 30 is operated at the reference rotational speed N in subsequent S44. Then, this routine ends.

  When the ECU 46 determines that the vehicle speed V is less than the threshold value Vb in S30, the ECU 46 sets the allowable rotational speed Np of the electric pump 30 based on the vehicle speed V in the subsequent S32. The permissible rotational speed Np is the maximum rotational speed among the rotational speeds of the electric pump 30 that can be masked by noise when the electric vehicle 10 travels at the vehicle speed V. Specifically, when the rotational speed of the electric pump 30 is switched in multiple stages, a larger value is set as the allowable rotational speed Np as the vehicle speed V is larger, and a smaller value is set as the allowable rotational speed Np as the vehicle speed V is smaller. Set. In addition, when the drive state of the electric pump can only be selected from ON and OFF, the allowable rotational speed is set to the OFF state, that is, Np = 0. Further, when the rotation speed of the electric pump 30 is switched steplessly, a value proportional to the vehicle speed V may be set as the allowable rotation speed N.

  When the value of the allowable rotational speed Np is set in S32, the ECU 46 performs torque distribution in S34 and operates the electric pump at a rotational speed smaller than the allowable rotational speed Np in subsequent S36. Then, this routine ends. Like the first embodiment, the flowchart of the second embodiment is also repeatedly executed with a predetermined period.

  As described above, according to the present embodiment, the ECU 46 switches the operating states of the two drive motors and the electric pump 30 according to changes in the vehicle speed V and the state of charge (SOC) of the high-voltage battery 12. Specifically, if the temperature Tmg of the front motor 18 is less than 120 ° C., the ECU 46 stops the electric pump 30 without performing torque distribution because the front motor 18 does not need to be cooled. Further, even if the temperature Tmg of the front motor 18 is 120 ° C. or higher, if the required torque Trqd is less than Tb, the driving torque of the front motor 18 is small and the temperature of the front motor 18 does not rise significantly, so torque distribution The electric pump 30 is stopped without performing the operation. Therefore, when the necessity for cooling the front motor 18 is low, the electric pump 30 is not operated, so that power saving of the entire electric vehicle 10 can be achieved.

  Further, according to the present embodiment, the ECU 46 determines that the state of charge (SOC) of the high voltage battery 12 is Q% even if the temperature Tmg of the front motor 18 is 120 ° C. or higher and the required torque Trqd is Tb or higher. If less, torque distribution is not performed and the electric pump 30 is operated at the reference rotational speed N. Therefore, when the state of charge (SOC) of the high-voltage battery 12 is insufficient, the reduction of the charge capacity of the high-voltage battery 12 is suppressed by operating the electric pump 30 that consumes less power than when torque distribution is performed. can do. Moreover, since the front motor 18 is cooled using the electric pump 30, it is possible to suppress the front motor 18 from being overheated.

  Further, according to the present embodiment, the ECU 46 has the temperature Tmg of the front motor 18 of 120 ° C. or higher, the required torque Trqd of Tb or higher, and the state of charge (SOC) of the high-voltage battery 12 of Q% or higher. However, if the vehicle speed V is equal to or higher than the threshold value Vb, the electric pump 30 is operated at the reference rotational speed N without performing torque distribution. Therefore, when the vehicle speed is fast and the noise such as road noise and wind noise in the vehicle is large, the operating sound of the electric pump 30 is masked by the noise, so it is difficult for the occupant to visually recognize the operating sound of the electric pump 30. Become. Moreover, since the front motor 18 is cooled using the electric pump 30, it can suppress that the front motor 18 exceeds allowable temperature.

  Further, according to the present embodiment, the ECU 46 has the temperature Tmg of the front motor 18 of 120 ° C. or higher, the required torque Trqd of Tb or higher, and the state of charge (SOC) of the high-voltage battery 12 of Q% or higher. When the vehicle speed V is less than the threshold value Vb, torque distribution is performed and the electric pump 30 is operated at a rotational speed smaller than the allowable rotational speed Np. Therefore, it is possible to suppress the front motor 18 from being overheated by torque distribution while satisfying the required torque Trqd. Further, the electric pump 30 is operated within a range of the allowable rotation speed Np or less set according to the vehicle speed V. Since the vehicle speed V and the level of noise in the vehicle have the relationship shown in FIG. 2, the allowable rotational speed Np is set according to the level of noise in the vehicle. Therefore, the electric pump 30 can be operated within a range masked by the noise in the vehicle, and it becomes difficult for the occupant to recognize the operation sound of the electric pump 30.

  Next, changes in the operation of the two drive motors and the electric pump 30 when the electric vehicle 10 of the second embodiment travels will be described with reference to FIG. FIG. 5 shows time on the horizontal axis and the state of each element on the vertical axis. Here, the rotational speed of the electric pump 30, the driving torque of the front motor 18, the driving torque of the rear motor 20, the vehicle speed, the state of charge (SOC) of the high-voltage battery 12, and the required torque are increased from the upper side to the lower side in FIG. They are shown in order. Although not shown, it is assumed that the temperature Tmg of the front motor 18 is 120 ° C. or higher in the time axis range in FIG.

  Here, until the time t1, the vehicle speed is Vb or more, the state of charge (SOC) of the high voltage battery 12 is Q% or more, and the required torque is Tb or more, and the flowchart of FIG. 4 is S22, S24, S26, S28, S30, S42. , S44 in this order. Torque distribution is not performed in S42, and the electric pump 30 operates without being limited by the reference rotational speed N in S44.

  At time t1, the vehicle speed V becomes equal to or less than the threshold value Vb. Therefore, after time t1 and before time t2, the vehicle speed is less than Vb, the state of charge (SOC) of the high voltage battery 12 is Q% or more, the required torque is Tb or more, and the flow chart of FIG. 4 is S22, S24, S26, S28. , S30, S32, S34, S36. Therefore, the driving torque of the front motor 18 is decreased and the driving torque of the rear motor 20 is increased as compared to immediately before time t1. Further, the electric pump 30 operates at the reference rotational speed N until immediately before the time t1, but after the time t1, the electric pump 30 is limited to operate at the allowable rotational speed Np.

  At time t2, the state of charge (SOC) of the high voltage battery 12 becomes Q% or less. Therefore, after time t2 and before time t3, the vehicle speed is less than Vb, the state of charge (SOC) of the high voltage battery 12 is less than Q%, the required torque is Tb or more, and the flowchart of FIG. 4 is S22, S24, S26, S28. , S42, S44. Therefore, the driving torque of the front motor 18 is increased and the driving torque of the rear motor 20 is decreased as compared to immediately before time t2. The electric pump 30 is limited to operate at the allowable rotational speed Np until immediately before the time t2, but the electric pump 30 increases the rotational speed and operates at the reference rotational speed N after the time t2. To be controlled.

  At time t3, the state of charge (SOC) of the high voltage battery 12 becomes Q% or more. Therefore, after time t3 and before time t4, the vehicle speed is less than Vb, the state of charge (SOC) of the high-voltage battery 12 is Q% or more, and the required torque is Tb or more. The flowchart of FIG. 4 is S22, S24, S26, S28. , S30, S32, S34, S36. Accordingly, the driving torque of the front motor 18 is decreased and the driving torque of the rear motor 20 is increased as compared to immediately before time t3. The electric pump 30 operates at the reference rotational speed N until immediately before time t3. However, the electric pump 30 is limited to operate at the allowable rotational speed Np after time t3.

  At time t4, the required torque becomes less than Tb. Therefore, after time t3 and before time t4, the vehicle speed is less than Vb, the state of charge (SOC) of the high-voltage battery 12 is Q% or more, and the required torque is less than Tb, and the flowchart of FIG. 4 is S22, S24, S26, S38. , S40 is followed in this order. Therefore, the driving torque of the front motor 18 is increased and the driving torque of the rear motor 20 is decreased as compared to immediately before time t4. Further, the electric pump 30 is limited to operate at the allowable rotational speed Np until immediately before time t4, but after time t4, the operation of the electric pump 30 is controlled to stop. In the second embodiment, the electric pump 30 is switched to stop at the time t4. However, the operation may be continued at the allowable rotational speed Np without stopping, or the rotational speed is less than the allowable rotational speed Np. May be switched to operate.

  At time t5, the required torque becomes Tb or more. The state of charge (SOC) of the high-voltage battery 12 becomes Q% or more. Therefore, after time t5, the vehicle speed is less than Vb, the state of charge (SOC) of the high-voltage battery 12 is Q% or more, and the required torque is Tb or more, and the flowchart of FIG. 4 is S22, S24, S26, S28, S30, The steps are followed in the order of S32, S34, and S36. Therefore, the driving torque of the front motor 18 is decreased and the driving torque of the rear motor 20 is increased as compared to immediately before time t5. Further, the operation of the electric pump 30 is stopped until immediately before time t5, but the electric pump 30 is controlled to operate at the allowable rotation speed Np after time t5.

  As described above, when the electric vehicle 10 of the second embodiment travels, the operating states of the two drive motors and the electric pump 30 according to changes in the vehicle speed V and the state of charge (SOC) of the high-voltage battery 12. Is switched to be optimal. Therefore, according to the state of the electric vehicle 10 at that time, the operation sound of the electric pump 30 can be limited as much as possible to ensure quietness in the vehicle. At the same time, the temperature rise of the front motor 18 can be suppressed, and the performance degradation due to overheating of the front motor 18 can be suppressed. The traveling state of the electric vehicle 10 shown in FIG. 5 is merely an example for explaining the second embodiment, and the transitions of the vehicle speed, the state of charge (SOC) of the high-voltage battery 12 and the required torque are limited to this. Is not to be done.

  In the first embodiment and the second embodiment, the case where the electric vehicle 10 is an electric vehicle including the front motor 18 and the rear motor 20 has been described. However, the present invention is also applicable to a hybrid vehicle having an engine as a driving source for traveling in addition to the front motor 18 and the rear motor 20. That is, in the present invention, the electric vehicle 10 includes a hybrid vehicle having an engine in addition to the front motor 18 and the rear motor 20 as a driving source for traveling.

  In the first embodiment and the second embodiment, the case where the two drive motors included in the electric vehicle 10 are the front motor 18 and the rear motor 20 has been described. However, in the present invention, both of these two drive motors may be arranged at the front, or both may be arranged at the rear. Further, the two drive motors may both transmit driving torque to the front wheels, or both may transmit driving torque to the rear wheels. Moreover, the magnitude | size of the output of two motors may be comparable. That is, in the present invention, the two drive motors are not limited by their arrangement or the like, and include all those that transmit power to the drive wheels.

  In the first embodiment and the second embodiment, the motor cooling device 26 is described as cooling the front motor 18. However, when the output of the rear motor 20 is large and there is a need for cooling, the rear motor 20 is installed. You may provide the motor cooling device to cool. Alternatively, two motors for driving may be simultaneously cooled using one motor cooling device 26.

  In the torque distribution in the first and second embodiments, the driving torque of the front motor 18 is decreased and the driving torque of the rear motor 20 is increased in order to suppress overheating of the front motor 18. . However, according to the present invention, when the output of the rear motor 20 is equal to or higher than the output of the front motor 18, the motor cooling device 26 cools the rear motor 20, and the driving torque of the front motor 18 is set for torque distribution. Simultaneously with the increase, the driving torque of the rear motor 20 may be decreased to suppress the rear motor 20 from being overheated. Further, another system identical to the system for suppressing overheating of the front motor 18 described in the first embodiment and the second embodiment may be provided, and the overheating of the rear motor 20 may be suppressed simultaneously.

  In the first and second embodiments, the noise level in the vehicle is estimated from the vehicle speed. However, in the present invention, a measuring instrument such as a microphone is installed in the vehicle to directly measure the noise level. May be.

  In the first and second embodiments, when torque is distributed, the rear motor 20 outputs all the torque, and if the rear motor 20 alone cannot output the required torque, the excessive torque is output. Is output by the front motor 18. However, in the present invention, the torque distribution method is not limited to this method. For example, when torque distribution is performed, the driving torque of the rear motor 20 may be set to a value in a range larger than the driving torque of the rear motor 20 before torque distribution. That is, the ratio of the driving torque of the front motor 18 to the required torque may be smaller after torque distribution than before torque distribution. In this way, the driving torque of the front motor 18 is reduced by torque distribution, so that the effect of suppressing overheating of the front motor 18 can be obtained.

  In the first and second embodiments, the noise in the vehicle is the noise including the operation sound of the electric pump 30. However, in the present invention, the noise in the vehicle may be noise other than the operation sound of the electric pump 30. Since the operation sound of the electric pump 30 does not depend on the vehicle speed, the electric pump 30 can be estimated by estimating the noise level from the vehicle speed V in this case as in the first and second embodiments. That is, the magnitude of noise other than the operation sound is estimated. Further, when directly measuring the loudness of the vehicle interior with a microphone or the like, noise other than the operational sound of the electric pump 30 is subtracted from the measured loudness by the amount of the operational sound of the electric pump 30. The size can be estimated. The loudness of the operation sound of the electric pump 30 may be estimated based on the number of rotations of the electric pump 30, or may be measured by a measuring instrument such as a microphone disposed in the vicinity of the electric pump 30. As described above, by making the noise level in the vehicle the noise in the vehicle excluding the operation sound of the electric pump 30, the following effects can be obtained in addition to the effects of the first and second embodiments. Can do. That is, even if the operation sound of the electric pump 30 is loud and the noise including the operation sound of the electric pump 30 in the vehicle is large, if the noise other than the operation sound of the electric pump 30 is low, the rotational speed of the electric pump 30 is reduced. It can be made small to ensure quietness in the vehicle.

  DESCRIPTION OF SYMBOLS 10 Electric vehicle, 12 High voltage battery, 14, 16 Inverter, 18 Front motor, 20 Rear motor, 22 Front wheel, 24 Rear wheel, 26 Motor cooling device, 28 Motor control device, 30 Electric pump, 32 Radiator, 34 Cooling piping, 36 Vehicle speed Sensor, 38 accelerator opening sensor, 40 torque detection means, 42 voltage sensor, 44 temperature sensor, 46 ECU.

Claims (1)

An electric pump,
A first drive motor cooled by a coolant supplied by the electric pump;
A second drive motor;
A control unit for controlling the electric pump and the two drive motors,
A drive device for an electric vehicle,
If the noise level in the car is less than the specified value,
Compared to the case of the predetermined value
The control unit reduces the rotational speed of the electric pump,
Reducing the torque of the first drive motor;
A drive device for an electric vehicle, wherein control is performed so as to increase the torque of the second drive motor.

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