JP2013169818A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle capable of suppressing a lowering of operability while suppressing the occurrence of slipping.SOLUTION: A detected demanded torque is obtained by being distributed to a front wheel demand torque and rear wheel demand torque. An electric motor 23 for a front wheel and an electric motor 33 for a rear wheel are controlled in response to a distributed demand torque amount. A control part 90 of an electric vehicle 10 corrects the front wheel demand torque and rear wheel demand torque by moving the torque from either of a front wheel 21 and rear wheel 31 which is slipping to the other in response to a slipping amount.

Description

  The present invention relates to an electric vehicle including an electric motor that drives a front wheel and an electric motor that drives a rear wheel.

  2. Description of the Related Art Conventionally, there is an electric vehicle that includes an electric motor that rotationally drives front wheels and an electric motor that rotationally drives rear wheels. In this type of electric vehicle, when one of the front wheels or the rear wheels slips, the ratio of torque distribution to the front wheels and the rear wheels is changed. The ratio is fixedly determined, and slipping is eliminated by changing the ratio (see, for example, Patent Document 1).

Japanese Patent No. 4227723

  In the technique of Patent Document 1, when the front wheel or the rear wheel slips, the torque ratio does not change according to the slip amount, so that the torque amount that moves from the slipped wheel to the other wheel increases, It is conceivable that the other wheel slips due to an excessive amount of torque borne by the other wheel. This causes a decrease in operability.

  An object of this invention is to provide the electric vehicle which can suppress the fall of operativity, suppressing generation | occurrence | production of a slip.

  The electric motor according to claim 1 is a front wheel motor that generates power for rotationally driving the front wheels, a rear wheel motor that generates power for rotationally driving the rear wheels, and a required torque detection that detects a required required torque. Means, front and rear wheel required torque distribution means for distributing the required torque to the front wheel and the rear wheel to obtain a front wheel required torque for the front wheel and a rear wheel required torque for the rear wheel, and the front and rear wheel required torque distribution Control means for controlling the front wheel motor and the rear wheel motor according to the amount of torque distributed by the means, slip detection means for detecting a slip state of the front wheel or the rear wheel, and the slip detection means. When a slip state is detected, the front wheel request torque is transferred by moving a torque corresponding to the slip amount from the slipping side of the front wheel and the rear wheel to the other side. And a correcting means for correcting the click and said rear wheel requested torque.

  In the electric vehicle according to claim 2, in the electric vehicle according to claim 1, the correction unit may be configured such that the correction value of the front wheel required torque or the correction value of the rear wheel required torque is a value indicating deceleration from a value indicating acceleration or When a value indicating deceleration is changed to a value indicating acceleration, the correction value of the direction of rotation is defined as zero and the other correction value is defined as the required torque.

  According to a third aspect of the present invention, in the electric vehicle according to the first or second aspect, the slip detection means detects a slip state based on a rotational speed difference between the front wheel and the rear wheel. The slip amount is determined based on the actual rotational speed difference between the front wheel and the rear wheel.

  According to a fourth aspect of the present invention, in the electric vehicle according to the fourth aspect, in the third aspect, the slip amount is determined by a target rotational speed difference between the front wheel and the rear wheel, which is determined according to a traveling state, and the actual rotational speed difference. It is determined according to the difference.

  According to a fifth aspect of the present invention, in the electric vehicle according to the third aspect, the absolute value of the difference between the target rotational speed difference and the actual rotational speed difference is not less than a predetermined value. Detect slip condition.

  According to the first aspect, the slip according to the slip amount moves from one of the front wheels and the rear wheels that slips to the other, thereby eliminating the slip. Furthermore, since the torque more than necessary does not move to the other due to the amount of movement of the torque according to the slip amount, the other wheel can be prevented from slipping due to the movement of the torque. Thus, according to the present invention, it is possible to suppress a decrease in operability of the electric vehicle while suppressing the occurrence of slip and lock.

  According to the second aspect of the present invention, when the correction value for the front wheel required torque or the rear wheel required torque changes from a value indicating acceleration to a value indicating deceleration or from a value indicating deceleration to a value indicating acceleration, the correction occurs. By specifying one correction value to zero and the other correction value to the required torque required for the electric vehicle, the driving system of the electric vehicle is simultaneously operated to accelerate and decelerate. As a result, there is no torsion caused by, and there is no deterioration in operability and no sound or vibration. For this reason, the comfort of an electric vehicle improves.

  According to a third aspect of the present invention, the slip detection means detects a slip state based on a difference in actual rotational speed between the front wheel and the rear wheel, and the slip amount is determined by the front wheel and the rear wheel. Therefore, it is easy to detect the slip state and easily determine the slip amount.

  According to a fourth aspect of the present invention, the slip amount is determined according to a difference between a target rotational speed difference between the front wheel and the rear wheel, which is determined according to a traveling state, and the actual rotational speed difference. Is done. For example, when the electric vehicle turns to the right, a rotational speed difference is generated between the front wheels and the rear wheels. As described above, the rotational speed difference is generated between the front wheel and the rear wheel according to the traveling state of the electric vehicle, but this is not a slip. According to the fourth aspect, the slip detection accuracy can be improved by detecting the slip according to the difference between the actual rotational speed difference and the target rotational speed difference.

  According to the fifth aspect of the present invention, when the difference between the actual rotational speed difference between the front wheels and the rear wheels and the target rotational speed difference is equal to or greater than a predetermined value, the slip state is detected, thereby detecting the actual rotational speed difference. Since the detection error and the detection error of the target rotational speed difference can be canceled, the slip detection accuracy can be improved.

Schematic which shows the electric vehicle which concerns on one Embodiment of this invention. The map which shows the moving torque amount which is the amount of torque which moves to the other according to the slip amount from the slipping or locking one of the front wheels or the rear wheels of the electric vehicle. The flowchart which shows operation | movement of the control part of the same electric vehicle. The table | surface which shows the state of cases 1-8 of the same electric vehicle.

  An electric vehicle according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing an electric vehicle 10 which is an example of an electric vehicle. As shown in FIG. 1, the electric vehicle 10 includes a front wheel drive system 20, a rear wheel drive system 30, a battery 40, a handle 50, a steering angle detection sensor 60, an accelerator pedal position sensor 70, and a brake pedal position. A sensor 80, a control unit 90, a front wheel drive shaft rotational speed detection sensor 120, and a rear wheel drive shaft rotational speed detection sensor 130 are provided.

  The front wheel drive system 20 includes a pair of front wheels 21, a front wheel drive shaft 22, a front wheel motor 23, a front wheel speed reducer 24, and a front wheel inverter 25 disposed on the front side of the vehicle body. One front wheel 21 and the other front wheel 21 are arranged one by one on the left and right in the front part of the vehicle body. The front wheel speed reducer 24 is connected to the output shaft of the front wheel motor 23 and decelerates the rotational speed of the output shaft of the front wheel motor 23. The front wheel drive shaft 22 is connected to the front wheel speed reducer 24 and the front wheel 21, and transmits the rotation of the output shaft of the front wheel motor 23 decelerated by the front wheel speed reducer 24 to the front wheel 21. The front wheel speed reducer 24 and the front wheel drive shaft 22 are an example of a transmission unit that transmits the torque generated by the front wheel motor 23 to the front wheel 21.

  The front wheel inverter 25 converts the electric power supplied from the battery 40 based on an instruction from the control unit 90 described later, and supplies the converted electric power to the front wheel electric motor 23. Further, during the deceleration operation of the electric vehicle 10, the torque required for the rotation of the output shaft of the front wheel motor 23 is controlled so that the front wheel motor 23 becomes resistance to rotation of the front wheel 21.

  The rear wheel drive system 30 includes a pair of rear wheels 31, a rear wheel drive shaft 32, a rear wheel motor 33, a rear wheel speed reducer 34, and a rear wheel inverter 35 disposed on the rear side of the vehicle body. It has. One rear wheel 31 and the other rear wheel 31 are arranged one by one on the left and right at the rear of the vehicle body. The rear wheel speed reducer 34 is connected to the output shaft of the rear wheel motor 33 and decelerates the rotational speed of the output shaft of the rear wheel motor 33. The rear wheel drive shaft 32 is connected to the rear wheel speed reducer 34 and the rear wheel 31, and transmits the rotation of the output shaft of the rear wheel motor 33 decelerated by the rear wheel speed reducer 34 to the rear wheel 31. To do. The rear wheel speed reducer 34 and the rear wheel drive shaft 32 are an example of a transmission unit that transmits the torque generated by the rear wheel motor 33 to the rear wheel 31.

  The rear wheel inverter 35 converts the electric power supplied from the battery 40 based on an instruction from the control unit 90 described later, and supplies the converted electric power to the rear wheel electric motor 33. Further, during the deceleration operation of the electric vehicle 10, the torque required for the rotation of the output shaft of the front wheel motor 23 is controlled so that the front wheel motor 23 becomes resistance to rotation of the front wheel 21.

  The handle 50 is operated when the driver changes the traveling direction. The steering angle detection sensor 60 detects the steering angle of the handle 50 and transmits a signal corresponding to the steering angle to the control unit 90 described later. The accelerator pedal position sensor 70 detects the position of the accelerator pedal that changes when the driver depresses the accelerator pedal 100 during traveling, and transmits a signal corresponding to the position of the accelerator pedal 100 to the control unit 90. The brake pedal position sensor 80 detects the position of the brake pedal 110 that changes when the driver depresses the brake pedal 110 when decelerating the electric vehicle 10, and sends a signal corresponding to the position of the brake pedal 110 to the control unit 90. Send.

  The front wheel drive shaft rotational speed detection sensor 120 detects the rotational speed of the front wheel drive shaft 22 and transmits a signal corresponding to the rotational speed of the front wheel drive shaft 22 to the control unit 90. The front wheel drive shaft 22 rotates integrally with the front wheel 21. For this reason, detecting the rotational speed of the front wheel drive shaft 22 means detecting the rotational speed of the front wheel 21. The rear wheel drive shaft rotational speed detection sensor 130 detects the rotational speed of the rear wheel drive shaft 32 and transmits a signal corresponding to the rotational speed of the rear wheel drive shaft 32 to the control unit 90. The rear wheel drive shaft 32 rotates integrally with the rear wheel 31. Detecting the rotational speed of the rear wheel drive shaft 32 is detecting the rotational speed of the rear wheel 31.

The control unit 90 has the following functions (1) to (5).
(1) A function of detecting a required torque T required for the electric vehicle 10 based on detection results of the accelerator pedal position sensor 70 and the brake pedal position sensor 80.
(2) The required torque is distributed to the front wheel 21 and the rear wheel 31 according to a predetermined distribution ratio, and the front wheel required torque TFreq required for the front wheel 21 and the rear wheel required torque TRreq required for the rear wheel 31 are obtained. Function to calculate.
(3) A function of detecting a slip of the front wheel 21 or the rear wheel 31 based on detection results of the front wheel drive shaft rotational speed detection sensor 120 and the rear wheel drive shaft rotational speed detection sensor 130 during acceleration operation of the electric vehicle 10. The acceleration operation is a state where the accelerator pedal 100 is depressed.

(4) If the front wheel 21 or the rear wheel 31 is slipping, the front wheel required torque TFreq and the rear wheel required torque TRreq are corrected, and the front wheel actual torque TF to be actually applied to the front wheel 21 and the actual rear A function of calculating the rear wheel actual torque TR to be applied to the wheel 31. The front wheel actual torque TF
Is a total value of torque to be applied to both front wheels 21 in the present embodiment. Each front wheel 21 is given 50% of the actual front wheel torque TF. The rear wheel actual torque TR is a total value of torques to be applied to both the rear wheels 31. Each rear wheel 31 is given 50% of the actual rear wheel torque TR.

(5) A function of controlling the front wheel motor 23 so that the front wheel actual torque TF acts on the front wheel 21 and controlling the rear wheel motor 33 so that the rear wheel actual torque TR acts on the rear wheel 31.
The function (1) will be described. Based on the detection result of the accelerator pedal position sensor 70, the control unit 90 determines that an acceleration request is made from the driver to the electric vehicle 10 when the accelerator pedal 100 is depressed. Based on the detection result, a required torque T required for the electric vehicle 10 is detected.

  The control unit 90 determines, based on the detection result of the brake pedal position sensor 80, that the driver has requested the vehicle to decelerate when the brake pedal 110 is depressed, and the brake pedal position sensor. Based on 80 detection results, the required torque T required for the electric vehicle 10 is detected. In the present embodiment, the required torque when requesting acceleration is positive, and the required torque when requesting deceleration is negative.

  Next, the function (2) will be described. The control unit 90 distributes the required torque T detected by the function (1) to the front wheels 21 and the rear wheels 31. That is, the front wheel required torque TFreq required for the front wheel 21 and the rear wheel required torque TRreq required for the rear wheel 31 are calculated. T = TFreq + TRreq.

  The distribution ratio of the required torque T to the front wheels 21 and the rear wheels 31 is determined in advance according to the traveling state of the electric vehicle 10 and is stored in the storage unit 91. The traveling state is, for example, the vehicle speed of the electric vehicle 10.

  A vehicle speed detection method in this embodiment will be described. One front wheel 21 is provided with a rotational speed detection sensor 200 that detects the rotational speed of the front wheel 21. The other front wheel 21 is provided with a rotation speed detection sensor 201 that detects the rotation speed of the front wheel 21. One rear wheel 31 is provided with a rotation detection sensor 202 that detects the number of rotations of the rear wheel 31. The other rear wheel 32 is provided with a rotational speed detection sensor 203 that detects the rotational speed of the rear wheel 31.

  The rotation speed detection sensors 200 to 203 transmit detection results to the control unit 90. The control unit 90 detects the wheel speed of each wheel based on the detection results of the rotation detection sensors 200 to 203. That is, the respective wheel speeds of one front wheel 21, the other front wheel 21, one rear wheel 31, and the other rear wheel 31 are detected.

  The control unit 90 sets the third fastest wheel among the four wheels as the vehicle body speed. On the other hand, when a slip is detected during acceleration, that is, when the required torque T is a positive value, the average value of the non-slip wheels, that is, the third or fourth fastest wheel speed of the four wheels is determined as the vehicle body speed. And When locking is detected during deceleration, that is, when the required torque T is a negative value, the vehicle speed is the average value of the wheel speeds that are not locked, that is, the first or second fastest wheel of the four wheels. . The method for obtaining the vehicle speed is an example, and the vehicle speed may be obtained by other methods.

  Next, the function (3) will be described. The control unit 90 sets the target rotational speed difference ΔNtgt between the rotational speed of the front wheel drive shaft 22 and the rotational speed of the rear wheel drive shaft 32, and the actual rotational speed difference between the rotational speed of the front wheel drive shaft 22 and the rotational speed of the rear wheel drive shaft 32. Based on the difference ΔN from ΔNact, the slip state between the front wheel 21 and the rear wheel 31 is detected. ΔN = (ΔNact) − (ΔNtgt). In the present embodiment, when the absolute value of the difference ΔN is equal to or greater than the predetermined value A, the control unit 90 determines that the front wheel 21 or the rear wheel 31 is slipping. A is a positive value. -A is a negative value.

  The target rotational speed difference ΔNtgt is a difference in rotational speed between the front wheels 21 and the rear wheels 31 that occurs during normal traveling of the electric vehicle 10. For example, when the driver rotates the handle 50 to the right to change the traveling direction to the right, the front wheel 21 tilts to the right. For this reason, a difference in rotational speed occurs between the front wheel 21 and the rear wheel 31. This is a rotational speed difference not caused by slip. Thus, the target rotational speed difference ΔNtgt is a rotational speed difference that is not caused by slip but occurs during normal traveling. In the present embodiment, the control unit 90 calculates the target rotational speed difference ΔNtgt based on the vehicle speed of the electric vehicle 10 and the steering angle of the steering wheel 50. More specifically, the control unit 90 is based on the detection result of the front wheel drive shaft rotational speed detection sensor 120, the detection result of the rear wheel drive shaft rotational speed detection sensor 130, and the detection result of the steering angle detection sensor 60. The target rotational speed difference ΔNtgt is calculated.

  The actual rotational speed difference ΔNact is a difference between the rotational speed of the rear wheel 31, that is, the rotational speed of the rear wheel drive shaft 32, and the rotational speed of the front wheel 21, that is, the rotational speed of the front wheel drive shaft 22. The control unit 90 detects the rotational speed Nr of the rear wheel drive shaft 32 based on the detection result of the rear wheel drive shaft rotational speed detection sensor 130, and the front wheel drive shaft based on the detection result of the front wheel drive shaft rotational speed detection sensor 120. The rotational speed Nf of 22 is detected. ΔNact = Nr−Nf.

  The predetermined value A is used to absorb detection errors and the like of each device used for obtaining the difference ΔN, such as the front wheel drive shaft rotation speed detection sensor, the rear wheel drive shaft rotation speed detection sensor 130, and the steering angle detection sensor 60. ing.

  In other words, when there is no error, the actual rotational speed difference ΔNact and the target rotational speed difference ΔNtgt are the same value when the front wheel 21 and the rear wheel 31 are not slipped, that is, the difference ΔN = 0. . The predetermined value A is used to prevent erroneous detection of slip between the front wheel 21 and the rear wheel 31. The predetermined value A is a value unique to the electric vehicle 10 and can be obtained by experiments or the like.

  In the present embodiment, the slip state is a state in which the absolute value of the difference ΔN is equal to or greater than the predetermined value A during the acceleration operation of the electric vehicle 10, that is, when the required torque is positive. When ΔN is equal to or greater than a predetermined value A, the rear wheel 31 is in a slipping state. When ΔN becomes equal to or less than the predetermined value −A, the front wheel 21 is slipping. This is because when the accelerator pedal 100 is depressed to accelerate the electric vehicle 10, slip occurs in one of the front wheel 21 and the rear wheel 31, so that the rotational speed of the front wheel 21 and the rotational speed of the rear wheel 31 are This is because a difference occurs between the two.

  In the present embodiment, the locked state is a state where the absolute value of the difference ΔN is equal to or greater than the predetermined value A when the electric vehicle 10 is decelerated, that is, when the required torque is negative. When ΔN is equal to or greater than a predetermined value A, the rear wheel 31 is in a locked state. When ΔN is equal to or less than the predetermined value −A, the front wheel 21 is locked. This is because when the accelerator pedal 100 is depressed to accelerate the electric vehicle 10, a lock is generated on one of the front wheels 21 and the rear wheels 31, so that the rotation speed of the front wheels 21 and the rotation speed of the rear wheels 31 are This is because a difference occurs between the two. The locked state is an example of the slip state referred to in the present invention.

  As described above, in the present embodiment, the control unit 90 uses the difference between the target rotational speed difference ΔNtgt and the actual rotational speed difference ΔNact, ΔN = (ΔNact) − (ΔNtgt), so that the front wheel 21 or the rear wheel 31 is used. It is possible to easily determine that slip has occurred.

  Next, the function (4) will be described. The control unit 90 calculates the front wheel required torque TFreq and the rear wheel required torque TRreq as described in the function (2). As a function (4), when the control unit 90 determines that one of the front wheel 21 and the rear wheel 31 is slipping, the control unit 90 corrects the front wheel required torque TFreq and the rear wheel required torque TRreq. As a correction, the torque corresponding to the slip amount is moved from the slipping one of the front wheel 21 and the rear wheel 31 to the other. In the present embodiment, as an example, the difference ΔN is used as the slip amount described above.

  As a result, the torque distributed to the slipping side of the front wheel 21 and the rear wheel 31 is reduced, so that the slip is eliminated and the torque is moved to the other side to the electric vehicle 10. The required torque T required is maintained.

  FIG. 2 is a map showing a moving torque amount ΔT, which is the amount of torque that moves from the slipping front wheel 21 or the rear wheel 31 to the other depending on the difference ΔN. In this embodiment, the moving torque amount ΔT corresponding to the slip amount is the minimum necessary torque amount that moves to eliminate the slip.

  The horizontal axis in FIG. 2 indicates the difference ΔN that is the slip amount. It shows that the difference ΔN increases as it proceeds along the arrow on the horizontal axis, in other words, as it proceeds to the right side in the figure. The vertical axis in FIG. 2 indicates the moving torque amount ΔT. In other words, the traveling torque amount ΔT increases as it proceeds along the arrow on the horizontal axis, in other words, as it proceeds upward in the figure.

  Here, the front wheel actual torque TF applied to the front wheel 21 and the rear wheel actual torque TR applied to the rear wheel 31 will be described. The front wheel actual torque TF is a torque that is actually applied to the front wheel 21 and is a value after the above correction is performed on the front wheel required torque TFreq. The correction value of the front wheel required torque TF is TFreq + ΔT. If no slip has occurred and therefore there is no need to correct the front wheel required torque TFreq, that is, if the absolute value of the difference ΔN is less than A, the front wheel actual torque TF = the front wheel required torque TFreq. It becomes.

  The actual rear wheel torque TR is a torque that is actually applied to the rear wheel 31 and is a value after the above correction is performed on the required rear wheel torque TRreq. The correction value of the rear wheel required torque TRreq is TRreq−ΔT. If no slip has occurred and therefore there is no need to correct the rear wheel required torque TRreq, that is, if the absolute value of the difference ΔN is less than A, the rear wheel actual torque TR = rear wheel The required torque TRreq is obtained. The required torque T = front wheel actual torque TF + rear wheel actual torque TR.

  The control unit 90 determines whether one of the correction value (TFreq + ΔT) of the front wheel required torque TFreq and the rear wheel required torque (TRreq−ΔT) is a value indicating acceleration from a value indicating acceleration, or a value indicating acceleration from a value indicating deceleration. When turning to, the torque of the turning side is made zero. This will be specifically described. When the electric vehicle 10 is accelerating, that is, when the required torque T is positive, both the front wheel required torque TFreq and the rear wheel required torque TRreq are positive. At this time, for example, if slip occurs in the front wheel 21, a correction value between the front wheel required torque TFreq and the rear wheel required torque TRreq is calculated according to the difference ΔN (slip amount). Specifically, the moving torque ΔT moves from the front wheel required torque TFreq to the rear wheel required torque TRreq.

  As a result, the correction value of the front wheel required torque TFreq becomes negative and the correction value of the rear wheel required torque TRreq may become positive. In such a state, the front wheel drive system 20 of the electric vehicle 10 operates to apply a negative torque to the front wheels 21, and the rear wheel drive system 30 operates to apply a positive torque to the rear wheels 31. Thus, acceleration control and deceleration control are mixed for the electric vehicle 10. Due to this mixture, the drive system of the electric vehicle 10 is twisted. The drive system of the electric vehicle 10 is a concept including the front wheel drive system 20 and the rear wheel drive system 30 in the present embodiment.

  Similarly, when the electric vehicle 10 is decelerating, that is, when the required torque T is negative, the front wheel required torque TFreq and the rear wheel required torque TRreq are both negative. At this time, for example, if slip occurs in the front wheel 21, a correction value between the front wheel required torque TFreq and the rear wheel required torque TRreq is calculated according to the difference ΔN (slip amount). Specifically, the moving torque ΔT moves from the front wheel 21 to the rear wheel 31.

  As a result, the correction value of the front wheel required torque TFreq becomes positive, and the correction value of the rear wheel required torque TRreq may become negative. In such a state, a positive torque is generated for the front wheel drive system 20 of the electric vehicle 10, and a negative torque is generated for the rear wheel drive system 30, and acceleration control and deceleration are performed for the electric vehicle 10. Control will be mixed. Due to this mixture, the drive system of the electric vehicle 10 is twisted.

  In the present embodiment, as a result of correcting the front wheel request torque TFreq and the rear wheel request torque TRreq, when both correction values do not change from a value indicating acceleration to a value indicating deceleration or from a value indicating deceleration to a value indicating acceleration, The front wheel actual torque TF = the front wheel required torque correction value TFreq + ΔT, and the rear wheel actual torque TR = the rear wheel required torque correction value TRreq−ΔT.

  As a result of correcting the front wheel request torque TFreq and the rear wheel request torque TRreq, if either of the correction values changes from a value indicating acceleration to a value indicating deceleration or from a value indicating deceleration to a value indicating acceleration, One actual torque is defined as zero, and the other actual torque is defined as the required torque T. By doing so, it is possible to maintain the required torque T required for the electric vehicle 10 while preventing the drive system of the electric vehicle 10 from being twisted.

  Next, the function (5) will be described. The controller 90 controls the front wheel motor 23 so that the front wheel actual torque TF obtained in the function (4) is applied to the front wheel 21 and the rear wheel actual torque TR is applied to the rear wheel 31. And the rear wheel motor 33 are controlled.

  Specifically, if the electric vehicle 10 is in an accelerating operation, the front wheel 21 is provided with the front wheel actual torque TF and the rear wheel 31 is provided with the rear wheel actual torque TR. The inverter 25 and the rear wheel inverter 35 are controlled. When the electric vehicle 10 is in a decelerating operation, a resistance of the front wheel actual torque TF is generated with respect to the rotation of the front wheel 21, and a resistance of the rear wheel actual torque TR is generated with respect to the rotation of the rear wheel 31. The front wheel inverter 25 and the rear wheel inverter 35 are controlled.

  Next, the operation of the control unit 90 will be described with reference to FIG. FIG. 3 is a flowchart showing the operation of the control unit 90. As shown in FIG. 3, in step ST1, the control unit 90 calculates a difference ΔN. Specifically, the control unit 90 calculates the target rotational speed difference ΔNtgt based on the detection results of the front wheel drive shaft rotational speed detection sensor 120, the rear wheel drive shaft rotational speed detection sensor 130, and the steering angle detection sensor 60. Further, the control unit 90 determines the actual rotational speed difference ΔNact = (the rotational speed NR of the rear wheel 31) from the detection result of the front wheel drive shaft rotational speed detection sensor 120 and the detection result of the rear wheel drive shaft rotational speed detection sensor 130. -(The rotational speed NF of the front wheel 21) is calculated.

  When the target rotational speed difference ΔNtgt and the actual rotational speed difference ΔNact are calculated, the difference ΔN = ΔNact−ΔNtgt is calculated. When the difference ΔN is calculated, the process proceeds to step ST2. In step T1, the control unit 90 detects the required torque T for the electric vehicle 10 based on the detection results of the accelerator pedal position sensor 70 and the brake pedal position sensor 80, and whether the electric vehicle 10 is in acceleration operation. Or it detects whether it is decelerating operation. When the accelerator pedal 100 is depressed, the required torque T is positive and acceleration operation is performed. When the brake pedal 110 is depressed, the required torque T is negative and the operation is decelerated. Further, based on the required torque T, a front wheel required torque TFreq and a rear wheel required torque TRreq are calculated according to the traveling state of the electric vehicle 10.

  In step ST2, the control unit 90 determines whether or not a slip has occurred in the front wheel 21 or the rear wheel 31 from the difference ΔN. Specifically, when the difference ΔN is equal to or greater than A, the rear wheel 31 slips, and when the difference ΔN is equal to or less than −A, the reverse is reversed when the front wheel 21 slips. If it is determined that slip has occurred in the front wheel 21 or the rear wheel 31, the moving torque amount ΔT is obtained from the map M shown in FIG. 2 based on the difference ΔN. When the moving torque amount ΔT is obtained, the process proceeds to step ST3. Note that the absolute value of the difference ΔN is less than A when there is no slip between the front wheel 21 and the rear wheel 31, and therefore the moving torque amount ΔT is zero from the map.

  In step ST3, based on the moving torque amount ΔT calculated in step ST2, the control unit 90 calculates a correction value (TFreq + ΔT) for the front wheel required torque TFreq and a correction value (TRreq−ΔT) for the rear wheel required torque TRreq. calculate. Then, the process proceeds to step ST4.

  In step ST4, whether or not the correction value (TFreq + ΔT) of the front wheel required torque TFreq has changed from a value indicating acceleration to a value indicating deceleration or a value indicating deceleration to a value indicating acceleration, that is, the correction value (TFreq + ΔT) is the required torque T. It is determined whether or not it is acting in the same direction. When the direction in which the correction value (TFreq + ΔT) acts and the direction in which the required torque T acts are the same, the process proceeds to step ST5. In addition, the direction of action said here shows whether it is positive or negative.

  In step ST5, the control unit 90 determines whether or not the correction value (TRreq−ΔT) of the rear wheel required torque TRreq has changed from a value indicating acceleration to a value indicating deceleration or from a value indicating deceleration to a value indicating acceleration. It is determined whether the direction in which the correction value (TRreq−ΔT) acts and the direction in which the required torque T acts are the same. When the direction in which (TRreq−ΔT) acts and the direction in which the required torque T acts are the same, the process proceeds to step ST6. In addition, the direction of action said here shows whether it is positive or negative.

  In step ST6, the control unit 90 operates in the direction in which the correction value (TFreq + ΔT) of the front wheel required torque TFreq and the correction value (TRreq−ΔT) of the rear wheel required torque TRreq are the same as the direction in which the required torque T acts. Therefore, the correction value (TFreq + ΔT) is set as the front wheel actual torque TF, and the correction value (TRreq−ΔT) is set as the rear wheel actual torque TR.

  If it is determined in step ST4 that the correction value (TFreq + ΔT) has changed from a value indicating acceleration to a value indicating deceleration or a value indicating deceleration to a value indicating acceleration, the process proceeds to step ST7, where the front wheel actual torque TF is set to zero. The rear wheel actual torque TR is set to the same value as the required torque T.

  If it is determined in step ST5 that the correction value (TRreq−ΔT) has changed from a value indicating acceleration to a value indicating deceleration or a value indicating deceleration to a value indicating acceleration, the process proceeds to step ST7, where the actual rear wheel torque TR is set. The front wheel actual torque TF is set to the same value as the required torque T.

  When the front wheel actual torque TF and the rear wheel actual torque TR are set in steps ST6, ST7, ST8, the process proceeds to step ST9. In step ST9, the control unit 90 controls the front wheel motor 23 so that the front wheel actual torque TF is applied to the front wheel 21, and the rear wheel actual torque TR is applied to the rear wheel 31. The electric motor 33 is controlled.

  Next, the operations of step ST1 to step ST9 will be described assuming specific cases 1 to 8. FIG. 4 shows the front wheel required torque TFreq, the rear wheel required torque TRreq, the moving torque amount ΔT, the front wheel required torque correction value (TFreq + ΔT), and the rear wheel required torque correction value in each of cases 1 to 8. 7 is a table showing (TRreq−ΔT), front wheel actual torque TF, and rear wheel actual torque TR. In all cases 1 to 8, since the absolute value of the difference ΔN is A or more, the slip occurs in either the front wheel 21 or the rear wheel 31.

  First, Case 1 will be described. As shown in FIG. 4, the case 1 is in an acceleration operation state when the driver depresses the accelerator pedal 100. In case 1, in step ST1, the control unit 90 detects 100 as the required torque, calculates 40 as the front wheel required torque TFreq, and calculates 60 as the rear wheel required torque TRreq. In addition, the value of the torque used by description of cases 1-8 is a rough value, and a unit is abbreviate | omitted. The controller 90 calculates −B as the difference ΔN. -A> -B. Then, the process proceeds to step ST2.

  In step ST2, the control unit 90 obtains −30 as the moving torque amount ΔT from the map M based on the difference ΔN = −B. Since −A> −B and −A> difference ΔN, in case 1, it is determined that the front wheel 21 is slipping during acceleration operation. Then, the process proceeds to step ST3.

  In step ST3, the control unit 90 calculates 10 as the correction value (TFreq + ΔT) of the front wheel required torque, and calculates 90 as the correction value (TRreq−ΔT) of the rear wheel required torque. That is, torque moves from the front wheel 21 to the rear wheel 31. The correction value (TFreq + ΔT) and the correction value (TRreq−ΔT) are both the same as the direction in which the required torque T acts. That is, both are positive values. Therefore, the control unit 90 sets 10 as the front wheel actual torque TF and sets 90 as the rear wheel actual torque TR in step ST6.

  Next, case 2 will be described. In case 2, the control unit 90 detects 100 as the required torque T in step ST1. For this reason, the control unit 90 determines that the electric vehicle 10 is in the accelerated operation state. Further, 40 is calculated as the front wheel required torque TFreq, and 60 is calculated as the rear wheel required torque TRreq. Further, the control unit 90 calculates −C as the difference ΔN. -A> -C. Then, the process proceeds to step ST2.

  In step ST2, the control unit 90 calculates −70 as the moving torque amount ΔT from the map M based on the difference ΔN = −C calculated in step ST1. Since -A> -C and -A> [Delta] N, in case 2, the control unit 90 determines that the front wheel 21 is slipping.

  In step ST3, the control unit 90 calculates −30 as the correction value (TFreq + ΔT) for the front wheel required torque, and calculates 130 as the correction value (TRreq−ΔT) for the rear wheel required torque. That is, torque moves from the front wheel 21 to the rear wheel 31. In Case 2, the correction value (TFreq + ΔT) is −30, which is negative, and has changed from a value indicating acceleration to a value indicating deceleration. Therefore, in step ST8, the control unit 90 sets zero as the front wheel actual torque TF, and sets 100, which is the same value as the required torque T, as the rear wheel actual torque TR.

  Next, the case 3 will be described. In case 3, the control unit 90 detects 100 as the required torque T in step ST1, and therefore determines that it is in the accelerated operation state. Further, the control unit 90 calculates 40 as the front wheel required torque TFreq and calculates 60 as the rear wheel required torque TRreq. Further, the control unit 90 calculates B as the difference ΔN. Then, the process proceeds to step ST2.

  In step ST2, the control unit 90 obtains 30 as a moving torque amount from the map M based on the calculated difference ΔN = B. Since A <B and A <ΔN, it is determined in Case 3 that the rear wheel 31 is slipping.

  In step ST3, the controller 90 calculates 70 as the front wheel required torque correction value (TFreq + ΔT), and calculates 30 as the rear wheel required torque correction value (TReq−ΔT). That is, torque moves from the rear wheel 31 to the front wheel 21. Since the direction in which the correction value (TFreq + ΔT) and the correction value (TRreq−ΔT) act is the same as the direction in which the required torque T acts, the control unit 90 sets 70 as the actual front wheel torque TF in step ST6. Then, 30 is set as the rear wheel actual torque TR.

  Next, the case 4 will be described. In step ST1, the control unit 90 detects 100 as the required torque T, and thus determines that it is in the acceleration operation state. Further, the control unit 90 calculates 40 as the front wheel required torque TFreq and calculates 60 as the rear wheel required torque TR. Further, the control unit 90 calculates C as the difference ΔN. Then, the process proceeds to step ST2.

  In step ST2, the control unit 90 obtains the moving torque amount ΔT from the map M based on the difference ΔN = C. Since A <C and A <ΔN, the control unit 90 determines that the rear wheel 31 is slipping in case 4.

  In step ST3, the control unit 90 calculates 110 as the correction value (TFreq + ΔT) of the front wheel required torque, and calculates −10 as the correction value (TRreq−ΔT) of the rear wheel required torque. That is, torque moves from the rear wheel 31 to the front wheel 21. In Case 4, the correction value for the required rear wheel torque changes from a value indicating acceleration to a value indicating deceleration. Therefore, in step ST5, the control unit 90 sets 100 as the front wheel actual torque TF, which is the same value as the required torque T, and sets zero as the rear wheel actual torque TR.

  Next, case 5 will be described. In step ST1, the control unit 90 detects -100 as the required torque T and determines that it is in a deceleration operation state. Then, the control unit 90 calculates −40 as the front wheel required torque TFreq and calculates −60 as the rear wheel required torque TRreq. Further, the control unit 90 calculates −B as the difference ΔN. -A> -B.

  In step ST2, the control unit 90 calculates −30 as the moving torque amount ΔT from the map M based on the difference ΔN = −B. Since −A> −B and −A> ΔN, in case 5, the control unit 90 determines that the rear wheel 31 is in a locked state.

  For example, when the rear wheel 31 is locked, the negative torque applied to the rear wheel 31 is large. Therefore, the rotational speed of the rear wheel 31 is higher than the rotational speed of the front wheel 21. It is small. For this reason, during the deceleration operation, the negative torque value is reduced to release the lock on the locked wheel. In other words, negative torque moves from the locked wheel to the other wheel. This indicates moving torque from the locked wheel to the other.

  In step ST3, the control unit 90 calculates −70 as the correction value (TFreq + ΔT) of the front wheel required torque, and calculates −30 as the correction value of the rear wheel required torque (TRreq−ΔT). That is, torque moves from the rear wheel 31 to the front wheel 21. The direction in which the correction value (TFreq + ΔT) and the correction value (TRreq−ΔT) act is the same as the direction in which the demand torque T acts, that is, the front wheel demand torque correction value is a value indicating deceleration. Since the correction value for the required rear wheel torque is a value indicating deceleration, the control unit 90 sets −70 as the front wheel actual torque TF and −30 as the rear wheel actual torque TR in step ST6.

  Next, the case 6 will be described. In step ST1, the control unit 90 detects -100 as the required torque and determines that it is in the deceleration operation state. Further, the controller 90 sets -40 as the front wheel required torque TFreq and sets -60 as the rear wheel required torque TRreq. Further, the control unit 90 calculates −C as the difference ΔN.

  In step ST2, the control unit 90 calculates −70 as the moving torque amount ΔT from the map M based on the difference ΔN = −C. Since −A> −C and −A> ΔN, in case 6, the control unit 90 determines that the rear wheel 31 is locked.

  In step ST3, the control unit 90 calculates −110 as the correction value (TFreq + ΔT) for the front wheel required torque, and calculates 10 as the correction value (TRreq−ΔT) for the rear wheel required torque. That is, torque moves from the rear wheel 31 to the front wheel 21. Since the rear wheel required torque TRreq is changed from negative to positive by correcting, the control unit 90 sets zero as the rear wheel actual torque TR and sets the required torque T as the front wheel actual torque TF in step ST7. Set -100 which is the same value.

  Next, the case 7 will be described. In step ST1, the control unit 90 detects -100 as the required torque T and determines that it is in a deceleration operation state. Further, -40 is calculated as the front wheel required torque TFreq, and -60 is calculated as the rear wheel required torque TRreq. Further, the control unit 90 calculates B as the difference ΔN.

  In step ST2, the control unit 90 obtains 30 as the moving torque amount ΔT from the map M based on the difference ΔN = B. Since A <B and ΔN> A, in case 7, it is determined that the front wheel 21 is locked.

  In step ST3, the control unit 90 calculates −10 as the correction value (TFreq + ΔT) of the front wheel required torque TFreq, and calculates −90 as the correction value (TRreq−ΔT) of the rear wheel required torque TRreq. That is, torque moves from the front wheel 21 to the rear wheel 31. Since both of the correction values remain negative, and therefore, the engine does not change from deceleration to acceleration, the controller 90 sets −10 as the front wheel actual torque TF and −− as the rear wheel actual torque TR in step ST6. 90 is set.

  Next, the case 8 will be described. In step ST1, the control unit 90 calculates -100 as the required torque T, and determines that it is in a deceleration operation state. -40 is calculated as the front wheel required torque TF, and -60 is calculated as the rear wheel required torque TR. Since the required torque T is negative, it is determined that the vehicle is in a deceleration operation state. Further, the control unit 90 calculates C as the difference ΔN.

  In step ST2, the control unit 90 obtains 70 as the moving torque amount ΔT from the map M based on the difference ΔN = C. Since A <C and A <ΔN, the control unit 90 determines that the front wheel 21 is locked.

  In step ST3, the control unit 90 calculates 30 as the correction value (TFreq + ΔT) of the front wheel required torque TFreq, and calculates −130 as the correction value (TRreq−ΔT) of the rear wheel required torque TRreq. That is, torque moves from the rear wheel 31 to the front wheel 21. In Case 8, since the front wheel required torque TFreq has changed from negative to positive by correction, that is, has changed from deceleration to acceleration, the control unit 90 sets zero as the front wheel actual torque TF in Step ST8, and the rear wheel. The required torque T is set to the same value of −100 as the actual torque TR.

  In the electric vehicle 10 configured as described above, if it is determined that slip has occurred in the front wheel 21 or the rear wheel 31, the occurrence of slip is prevented by moving torque from the slipping wheel to the other wheel, The required torque T required for the electric vehicle 10 is maintained. Thus, the acceleration operation of the electric vehicle 10 is maintained when the driver depresses the accelerator pedal 100 to accelerate. Further, when the driver depresses the brake pedal 110 to decelerate, the deceleration operation of the electric vehicle 10 is maintained.

  Further, the torque amount ΔT to be moved is determined according to the difference ΔN that is the slip amount. That is, when the slip occurs in the front wheel 21 or the rear wheel 31, the torque distribution ratio is not changed to a preset torque distribution amount. Therefore, the amount of torque that moves from the slipped wheel increases, and the other wheel Since the amount of torque to be borne becomes too large, the other wheel does not slip, so that the operability of the electric vehicle 10 does not deteriorate.

  Further, if the correction value obtained by correcting the torque required for one wheel and the torque required for the other wheel to avoid slipping is opposite to the direction in which the required torque T acts, in other words, acceleration When the value indicating the deceleration is changed to the value indicating the deceleration or the value indicating the deceleration to the value indicating the acceleration, the actual torque of the changed direction is set to zero, and the other torque is set to the same value as the required torque. As a result, the drive system of the electric vehicle 10 is not twisted, so that the operability caused by the twist is not deteriorated and no sound or vibration is generated.

  Thus, in this embodiment, the fall of the operativity and comfort of the electric vehicle 10 can be suppressed, suppressing generation | occurrence | production of a slip.

  Further, the slip of the front wheel 21 or the rear wheel 31 is detected based on the difference in rotational speed between the front wheel 21 and the rear wheel 31, and the slip amount is determined based on the rotational speed difference between the front wheel 21 and the rear wheel 31. Detected. For this reason, it is easy to obtain the slip amount.

  Further, by considering the target rotational speed difference when detecting the slip, it is possible to suppress erroneous recognition of the rotational speed difference between the front wheel 21 and the rear wheel 31 generated according to the traveling state of the electric vehicle 10 as slip. Thus, the slip detection accuracy can be improved.

  Further, when determining the slip, by considering the predetermined value A, various devices used for detecting the slip, for example, the front wheel drive shaft rotation speed detection rod 120, the rear wheel drive shaft rotation speed detection sensor 130, are used. Therefore, it is possible to suppress erroneous detection of slips due to detection errors such as the above, so that the slip detection accuracy can be improved.

  In the present embodiment, the difference in rotational speed between the front wheel 21 and the rear wheel 31 is used to detect the slip amount. As another example, for example, when the diameter of the front wheel 21 and the diameter of the rear wheel 31 are different, the peripheral speed on the ground contact surface of the front wheel 21 and the peripheral speed on the ground contact surface of the rear wheel 31 The slip may be detected using the difference. In this case, the difference between the circumferential speed on the ground contact surface of the front wheel 21 and the circumferential speed on the ground contact surface of the rear wheel 31 is the slip amount.

  In the present embodiment, the accelerator pedal position sensor 70, the brake pedal position sensor 80, and the control unit 90 constitute an example of a required torque detection unit. The control unit 90 is an example of front and rear wheel required torque distribution means. The front wheel drive shaft rotational speed detection sensor 120, the control unit 90, and the steering angle detection sensor 60 are used to calculate the difference ΔN. For this reason, in this embodiment, an example of a slip detection means is comprised. The control unit 90 is an example of a correction unit. The control unit 90 is an example of a control unit.

  The electric vehicle 10 is an example of an electric vehicle. As another example, for example, a train traveling on a track may be used. As another example, the electric vehicle may be a hybrid vehicle equipped with an electric motor and an internal combustion engine. As described above, the electric vehicle includes an electric vehicle equipped with only the electric motor, a hybrid vehicle equipped with both the electric motor and the internal combustion engine, and the like.

  Note that the slip state and the locked state of the present embodiment are examples of the slip state referred to in the present invention.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, you may delete some components from all the components shown by embodiment mentioned above.

  DESCRIPTION OF SYMBOLS 10 ... Electric vehicle (electric vehicle), 23 ... Front wheel motor, 33 ... Rear wheel motor, 60 ... Steering angle detection sensor (slip detection means), 70 ... Accelerator pedal position sensor (request torque detection means), 80 ... Brake Pedal position sensor (required torque detection means), 90 ... control unit (required torque detection means, slip detection means, correction means, control means), 120 ... front wheel drive shaft rotational speed detection sensor (slip detection means), 130 ... rear wheel Drive shaft rotation speed detection sensor (slip detection means).

Claims (5)

A front wheel motor that generates power to rotate the front wheels;
A rear wheel electric motor that generates power for rotationally driving the rear wheel;
Requested torque detecting means for detecting required requested torque;
Front and rear wheel required torque distribution means for distributing the required torque to the front wheel and the rear wheel to obtain a front wheel required torque for the front wheel and a rear wheel required torque for the rear wheel;
Control means for controlling the front wheel motor and the rear wheel motor according to the amount of torque distributed by the front and rear wheel required torque distribution means;
Slip detecting means for detecting a slip state of the front wheel or the rear wheel;
When the slip detection means detects a slip state, the front wheel required torque and the rear wheel required torque are obtained by moving the torque corresponding to the slip amount from the slipping side of the front wheel and the rear wheel to the other. An electric vehicle comprising: correction means for correcting. When the correction value of the front wheel required torque or the correction value of the rear wheel required torque changes from a value indicating acceleration to a value indicating deceleration or from a value indicating deceleration to a value indicating acceleration, the correction means The electric vehicle according to claim 1, wherein a correction value is defined as zero and the other correction value is defined as the required torque. The slip detecting means detects a slip state based on a difference in rotational speed between the front wheel and the rear wheel;
The electric vehicle according to claim 1, wherein the slip amount is determined based on a difference in actual rotational speed between the front wheel and the rear wheel. The slip amount is determined according to a difference between a target rotational speed difference between the front wheel and the rear wheel, which is determined according to a traveling state, and the actual rotational speed difference. The described electric car. The slip detection means detects a slip state when an absolute value of a difference between the target rotational speed difference and the actual rotational speed difference is a predetermined value or more. Electric car.

Images