JP2007099081A - Vehicle and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a shock from being applied to a driver, and suppress excessive power from being input to a battery in a vehicle equipped with a motor capable of outputting the power to a drive wheel and a battery for exchanging the power with the motor. <P>SOLUTION: The vehicle sets (S160) a target slip speed Vslip* to the trend to be smoothly small as the vehicle speed is large when a TRC switch is turned off (S140), and outputs (S170 to S200) a torque limiting a requested torque Td* from the motor 22 to a drive wheel by using a torque limit coefficient α based on the deviation between a slip speed Vslip and the target slip speed Vslip*. The torque output to the drive wheel can be suppressed from being suddenly changed accompanied with the change of the vehicle speed thereby. As the result, it can be suppressed to apply a sense of incongruity to a driver. The excessive power due to the sudden change of the driving state of the motor can be suppressed from being input to the battery. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle and a control method thereof.

Conventionally, as this type of vehicle, a vehicle including a motor that rotationally drives drive wheels has been proposed (see, for example, Patent Document 1). In this vehicle, a new speed command value is set based on a difference between the current speed command value and the actual speed of the vehicle body and a preset standard acceleration, and the motor is controlled based on the set speed command value. This prevents the drive wheels from slipping.
JP-A-9-140009

  In such a vehicle, if the drive wheels are controlled so as not to slip, the vehicle may not be able to escape from the stack at a low vehicle speed such as when starting, or a sufficient acceleration performance may not be obtained at a certain vehicle speed. In order to solve these problems, it is conceivable that the vehicle travels while allowing a relatively large slip at a low vehicle speed, while allowing a slight slip in consideration of the stability of the vehicle at a certain vehicle speed. Sometimes, if the allowable slip is suddenly changed with respect to the change in vehicle speed, the driving force output to the drive wheels is suddenly changed to shock the driver, or the driving state of the motor is suddenly changed. Excessive power may be input to or output from the battery that exchanges power with the motor.

  One object of the vehicle and the control method thereof according to the present invention is to suppress a shock to the driver. Another object of the vehicle and the control method thereof according to the present invention is to prevent excessive electric power from being input to and output from the power storage device.

  The vehicle and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above-described object.

The vehicle of the present invention
A vehicle including a drive source capable of outputting a driving force to a drive wheel,
Vehicle speed detection means for detecting the vehicle speed;
Wheel speed detection means for detecting a wheel speed that is at least the rotational speed of the drive wheel;
Slip speed calculating means for calculating a slip speed as a degree of slip of the drive wheel based on the detected vehicle speed and the detected wheel speed;
When the detected vehicle speed is less than the first vehicle speed, the drive source is controlled so that the calculated slip speed is within a first allowable range, and the detected vehicle speed is greater than the first vehicle speed. When the vehicle speed is equal to or higher than 2, the drive source is controlled so that the calculated slip speed is within a second allowable range different from the first allowable range, and the detected vehicle speed is equal to or higher than the first vehicle speed. When the speed is less than the second vehicle speed, the drive source is controlled so that the calculated slip speed is within the transition allowable range for smoothly shifting between the first allowable range and the second allowable range. Control means to
It is a summary to provide.

  In the vehicle according to the present invention, the slip speed as the degree of slip of the drive wheel is calculated based on the vehicle speed and at least the wheel speed that is the rotational speed of the drive wheel. When the vehicle speed is less than the first vehicle speed, the slip speed is The drive source is controlled to be within an allowable range of 1, and when the vehicle speed is equal to or higher than a second vehicle speed greater than the first vehicle speed, the slip speed is driven to be within a second allowable range different from the first allowable range. When the vehicle speed is equal to or higher than the first vehicle speed and lower than the second vehicle speed, the slip speed is within the transition allowable range for smoothly shifting between the first allowable range and the second allowable range. Control the drive source. Therefore, since the allowable range of the slip speed is smoothly changed as the vehicle speed changes, it is possible to suppress a sudden change in the driving force output to the drive wheels as the allowable range changes suddenly. As a result, it is possible to suppress a shock to the driver accompanying a sudden change in the driving force. Here, the second allowable range may be a range in which the calculated slip speed is more limited than the first allowable range.

  Such a vehicle of the present invention includes a required driving force setting means for setting a required driving force for traveling, and the control means is within the first allowable range when the detected vehicle speed is less than the first vehicle speed. Is set as a target slip speed, and when the detected vehicle speed is equal to or higher than the second vehicle speed, a second speed within the second allowable range is set as the target slip speed, and the detection is performed. When the generated vehicle speed is equal to or higher than the first vehicle speed and lower than the second vehicle speed, a transition speed for smoothly transitioning the first speed and the second speed within the transition allowable range is A driving force that is set as a target slip speed and restricts the set required driving force using a driving force limit that is set based on the calculated slip speed and the set target slip speed is the drive It may be assumed to be a means for controlling so as to be output to. If it carries out like this, the driving force which limited the required driving force using the driving force restriction based on the slip speed and the target slip speed can be output to the driving wheel. In this case, the control means sets a predetermined value to the driving force limit when the calculated slip speed is equal to the set target slip speed, and the calculated slip speed is smaller than the set target slip speed. In some cases, the driving force limit is set so that the greater the deviation between the slip speed and the target slip speed, the smaller the degree of limiting the set required driving force compared to the predetermined value, and the calculation is performed. When the slip speed is larger than the set target slip speed, the degree of limiting the set required driving force as compared with the predetermined value tends to increase as the deviation between the slip speed and the target slip speed increases. It may be a means for setting a driving force limit. In this way, it is possible to suppress the slip speed from greatly exceeding the target slip speed.

  In the vehicle according to the present invention, the drive source may include an electric motor capable of outputting a driving force, and may include power storage means capable of exchanging electric power with the drive source. The drive source is connected to an internal combustion engine, an output shaft of the internal combustion engine, and a drive shaft connected to the drive wheel, and drives at least part of the power from the internal combustion engine with input and output of electric power and power. An electric power driving input / output means for outputting to the shaft and an electric motor capable of inputting / outputting power to the driving shaft may be provided, and an electric storage means capable of exchanging electric power with the driving source may be provided. In these cases, it is possible to suppress a sudden change in the driving state of the electric motor by suppressing the sudden change in the allowable range. As a result, excessive power can be prevented from being input to and output from the power storage means. In the vehicle of the present invention in which the drive source includes an electric motor, the drive source includes a drive circuit that drives the electric motor, and the first allowable range and / or the second allowable range is the electric motor. It can also be a range set based on at least one of the rating, the capacity of the drive circuit, and the capacity of the power storage means. In this way, the first allowable range and the second allowable range can be set more appropriately.

  Further, the vehicle of the present invention further includes an allowable range change switch for changing an allowable range for allowing the calculated slip speed by a driver's operation, and the control means detects the detection when the allowable range change switch is OFF. Regardless of the vehicle speed, the drive source is controlled so that the calculated slip speed is within the third allowable range, which is more limited than the second allowable range, and when the allowable range change switch is on. Means for controlling the drive source so that the calculated slip speed is within the first allowable range, the second allowable range, or the transition allowable range based on the detected vehicle speed. It can also be. If it carries out like this, slip speed can be made into the tolerance | permissible_range according to the state of the permissible_range change switch.

  Alternatively, the vehicle according to the present invention further includes a braking force applying unit capable of applying a braking force to the driving wheel, and the control unit is configured to apply the driving source and the braking force when the detected vehicle speed is equal to or higher than the second vehicle speed. It can also be a means for controlling the giving means.

The vehicle control method of the present invention includes:
A vehicle control method including a drive source capable of outputting a drive force to a drive wheel,
(A) calculating a slip speed as a degree of slip of the drive wheel based on a vehicle speed and at least a wheel speed which is a rotation speed of the drive wheel;
(B) When the vehicle speed is less than the first vehicle speed, the drive source is controlled so that the calculated slip speed is within a first allowable range, and the second vehicle speed is greater than the first vehicle speed. In this case, the drive source is controlled so that the calculated slip speed is within a second allowable range different from the first allowable range, and the detected vehicle speed is equal to or higher than the first vehicle speed. When the vehicle speed is less than 2, the drive source is controlled so that the calculated slip speed is within a transition allowable range for smoothly shifting between the first allowable range and the second allowable range. The gist.

  According to the vehicle control method of the present invention, the slip speed as the degree of slip of the drive wheel is calculated based on the vehicle speed and at least the wheel speed that is the rotational speed of the drive wheel, and the vehicle speed is less than the first vehicle speed. Sometimes the drive source is controlled so that the slip speed is within the first allowable range, and when the vehicle speed is equal to or higher than the second vehicle speed, which is greater than the first vehicle speed, the second allowable range is different from the first allowable range. The driving allowance is controlled so that the slip speed smoothly shifts between the first allowable range and the second allowable range when the vehicle speed is higher than the first vehicle speed and lower than the second vehicle speed. The drive source is controlled to be within the range. Therefore, since the allowable range of the slip speed is smoothly changed as the vehicle speed changes, it is possible to suppress a sudden change in the driving force output to the drive wheels as the allowable range changes suddenly. As a result, it is possible to suppress a shock to the driver accompanying a sudden change in the driving force.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 22 that can input and output power to a drive shaft 28 connected to drive wheels 30 a and 30 b via a differential gear 31, and an inverter 24 that drives the motor 22. A battery 26 that exchanges electric power with the motor 22 and a main electronic control unit 50 that controls the entire vehicle.

  The motor 22 is configured as a synchronous generator motor that functions as an electric motor and functions as a generator. Further, the inverter 24 converts the DC power from the battery 26 into three-phase AC power by switching of the switching element and supplies it to the motor 22.

  The main electronic control unit 50 is configured as a microprocessor centered on the CPU 52, and includes a ROM 54 for storing processing programs, a RAM 56 for temporarily storing data, and an input / output port (not shown) in addition to the CPU 52. The main electronic control unit 50 includes a wheel speed sensor that detects the rotational position θm from the rotational position detection sensor 23 that detects the rotational position of the rotational shaft (drive shaft 28) of the motor 22 and the wheel speeds of the drive wheels 30a and 30b. The wheel speeds Vfl and Vfr from 34a and 34b, the wheel speeds Vrl and Vrr from the wheel speed sensors 34c and 34d for detecting the wheel speeds of the non-driven wheels 32a and 32b, the ignition signal from the ignition switch 60, and the operation of the shift lever 61 Shift position SP from the shift position sensor 62 that detects the position, accelerator opening Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63, and brake pedal position sensor 66 that detects the depression amount of the brake pedal 65 Brake pedal position BP, The vehicle speed V from the speed sensor 68 is set to the normal on state and from the TRC switch 69 which increases the allowable range for allowing the slip speed as the degree of slip of the drive wheels 30a and 30b when turned off by the driver. The on / off signal is input through the input port. Although details of the TRC switch 59 will be described later, in the embodiment, when the TRC switch 69 is on, the traction for controlling the motor 22 so that the slip speed is within a relatively small allowable range in order to ensure the stability of the vehicle. Control (TRC) was performed. The main electronic control unit 50 is attached to the switching control signal to the switching element of the inverter 24, the drive signal to the hydraulic brakes 40a and 40b attached to the drive wheels 30a and 30b, and the non-drive wheels 32a and 32b. The drive signals to the hydraulic brakes 40c and 40d are output via the output port.

  Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly the operation when traveling while allowing a certain amount of slip due to idling of the drive wheels 30a, 30b will be described. FIG. 2 is a flowchart illustrating an example of a drive control routine executed by the main electronic control unit 50 of the embodiment. This routine is repeatedly executed every predetermined time (for example, every several msec).

  When the drive control routine is executed, the CPU 52 of the main electronic control unit 50 firstly, the accelerator opening Acc from the accelerator pedal position sensor 64, the vehicle speed V from the vehicle speed sensor 68, and the drive wheels from the wheel speed sensors 34a and 34b. 30a, 30b wheel speeds Vfl, Vfr, a process for inputting data necessary for control such as an ON / OFF signal from the TRC switch 69 is executed (step S100), and the vehicle is based on the input accelerator opening Acc and the vehicle speed V. The required torque Td * for travel is set (step S110). In the embodiment, the required torque Tr * is determined in advance by storing the relationship between the accelerator opening Acc, the vehicle speed V, and the required torque Tr * in the ROM 54 as a required torque setting map, and the accelerator opening Acc, the vehicle speed V, and the like. , The corresponding required torque Tr * is derived and set from the stored map. FIG. 3 shows an example of the required torque setting map.

  Subsequently, the larger value of the wheel speeds Vfl, Vfr of the drive wheels 30a, 30b is set as the drive wheel speed Vf (step S120), and the slip speed Vslip is obtained by subtracting the vehicle speed V from the calculated drive wheel speed Vf. Is calculated (step S130). The processes in steps S120 and S130 are processes for calculating the slip speed of the drive wheel having a large degree of slippage due to idling, and the value is substantially 0 when both of the drive wheels 30a and 30b are completely gripped. Then, the state of the TRC switch 69 is checked (step S140). When the TRC switch 69 is on, a predetermined speed Vs1 is set as the target slip speed Vslip * (step S150). Here, the target slip speed Vslip * is set as a value within the allowable range, and the predetermined speed Vs1 is a value within the allowable range when the TRC switch 69 is on, the rating of the motor 22, the capacity of the inverter 24, It is set based on the capacity of the battery 26, and is set to 5 km / h or 10 km / h, for example. Now, consider the case where the driver has stepped on the accelerator pedal 63 to escape from the stack. When the TRC switch 69 is on, as described above, the motor 22 is controlled so that the slip speed Vslip is within a relatively small allowable range, so that it may not be possible to escape from the stack. On the other hand, when the TRC switch 69 is turned off by the driver, the escape performance from the stack can be ensured by increasing the allowable range. The reason for checking the state of the TRC switch 69 at step 140 is to determine whether or not the driver is requesting that the allowable range be increased.

  When the slip speed Vslip and the target slip speed Vslip * are set, a slip speed deviation ΔVslip is calculated by subtracting the target slip speed Vslip * from the set slip speed Vslip (step S170), and torque is calculated based on the calculated slip speed deviation ΔVslip. A limit coefficient α is set (step S180), the torque command Tm * of the motor 22 is calculated by multiplying the set torque limit coefficient α by the required torque Td * (step S190), and the motor 22 is calculated using the calculated torque command Tm *. Is controlled so as to be driven (step S200), and the drive control routine is terminated. Here, in the embodiment, the torque limit coefficient α is determined in advance by experimentally determining the relationship between the slip speed deviation ΔVslip and the torque limit coefficient α and stored in the ROM 54 as a torque limit coefficient setting map. , The corresponding torque limit coefficient α is derived from the stored map and set. An example of the torque limit coefficient setting map is shown in FIG. As shown in the figure, the torque limit coefficient α is set to a value of 1 when the slip speed deviation ΔVslip is less than the negative predetermined value V0, and when the slip speed deviation ΔVslip is equal to or greater than the predetermined value V0, the slip speed deviation ΔVslip is 0. In some cases, the predetermined value α1 is set and the slip speed deviation ΔVslip is set to tend to decrease from the value 1 toward the value 0, and the slip speed Vslip is set to a value that does not fall outside the allowable range described above. Here, the predetermined value V0 is set to a value whose absolute value is smaller than the predetermined speed Vs1. Therefore, when both the drive wheels 30a and 30b are completely gripped, the slip speed deviation ΔVslip is a value (−Vs1), and thus the torque limit coefficient α is set to a value 1. By setting the torque limiting coefficient α in this way, the torque output from the motor 22 to the drive wheels 30a and 30b decreases as the slip speed deviation ΔVslip (= Vslip−Vslip *) increases, so that the slip speed Vslip becomes the target. It can be suppressed that the slip speed Vslip * is greatly exceeded. As a result, when the TRC switch 69 is on, the vehicle travels while performing traction control (TRC) for controlling the motor 22 so that the slip speed Vslip is within a relatively small allowable range. When the drive wheels 30a and 30b are both gripped completely, the vehicle travels while outputting the required torque Td * from the motor 22 to the drive wheels 30a and 30b.

  On the other hand, when the TRC switch 69 is OFF in step S140, the target slip speed Vslip * is set based on the vehicle speed V (step S160), and the slip speed deviation ΔVslip is reduced by subtracting the target slip speed Vslip * from the slip speed Vslip. The torque limit coefficient α is set based on the slip speed deviation ΔVslip (step S180), and the torque command Tm * of the motor 22 is calculated using the torque limit coefficient α and the required torque Td * (step S170) In step S190, the motor 22 is controlled (step S200), and the drive control routine is terminated. Here, the target slip speed Vslip * when the TRC switch 69 is OFF is stored in the ROM 54 as a target slip speed setting map by experimentally determining the relationship between the vehicle speed V and the target slip speed Vslip * in the embodiment. In addition, when the vehicle speed V is given, the corresponding target slip speed Vslip * is derived and set from the stored map. An example of the target slip speed setting map is shown in FIG. In the figure, the solid line shows the target slip speed Vslip * when the TRC switch 69 is off, and for reference, the target slip speed Vslip * (predetermined speed Vs1) when the TRC switch 69 is on is shown as a one-dot chain line. As shown in the figure, the target slip speed Vslip * when the TRC switch 69 is OFF is set to a relatively large predetermined speed Vs2 when the vehicle speed V is less than the predetermined vehicle speed V1, and the predetermined vehicle speed V2 is greater than the predetermined vehicle speed V1. The predetermined speed Vs3 smaller than the predetermined vehicle speed V2 and larger than the predetermined vehicle speed Vs1 is set at the above time, and when the vehicle speed V is equal to or higher than the predetermined vehicle speed V1 and lower than the predetermined vehicle speed V2, the predetermined speed Vs2 and the predetermined speed Vs3 are Was set to transition smoothly. Here, the predetermined speed Vs2 is a value within a permissible range when the TRC switch 69 is off and the vehicle speed V is less than the predetermined vehicle speed V1, such as the rating of the motor 22, the capacity of the inverter 24, the capacity of the battery 26, and the like. For example, it is set to 35 km / h or 40 km / h. The predetermined speed Vs3 is based on the rating of the motor 22, the capacity of the inverter 24, the capacity of the battery 26, etc. as a value within an allowable range when the TRC switch 69 is OFF and the vehicle speed V is equal to or higher than the predetermined vehicle speed V2. For example, it is set to 15 km / h or 20 km. The allowable range when the TRC switch 69 is off and the vehicle speed V is equal to or higher than the predetermined vehicle speed V2 is greater than the allowable range when the TRC switch 69 is off and the vehicle speed V is less than the predetermined vehicle speed V1. The range is set to be smaller and larger than the allowable range when the TRC switch 69 is off. Consider a case where the driver depresses the accelerator pedal 63 greatly when the TRC switch 69 is on. At this time, as described above, since the target slip speed Vslip * is set to a relatively small predetermined speed Vs1, it is not possible to escape from the stack at a low vehicle speed such as when starting, or sufficient acceleration performance at a certain vehicle speed. May not be obtained. In order to solve these problems, when the TRC switch 69 is turned off by the driver, a relatively large predetermined vehicle speed Vs2 is set as the target slip speed Vslip * at a low vehicle speed, and the vehicle stability is also maintained at a certain vehicle speed. Considering this, it is conceivable to set the target slip speed Vslip * to a predetermined speed Vs3 that is smaller than the predetermined speed Vs2 and greater than the predetermined speed Vs1, but in this case, the target slip is increased as the vehicle speed V increases due to depression of the accelerator pedal 63. When the speed Vslip * changes suddenly from the predetermined speed Vs2 to the predetermined speed Vs3, the slip speed deviation ΔVslip changes suddenly, the torque limiting coefficient α changes suddenly, and the output from the motor 22 to the drive wheels 30a, 30b changes suddenly, making the driver feel uncomfortable. Give too much power to the battery 26 May occur. Therefore, in the embodiment, when the vehicle speed V is less than the predetermined vehicle speed V1, the predetermined speed Vs2 is set to the target slip speed Vslip *, and when the vehicle speed V is equal to or higher than the predetermined vehicle speed V2, the predetermined speed Vs3 is set to the target slip speed Vslip *. When the vehicle speed V is equal to or higher than the predetermined vehicle speed V1 and lower than the predetermined vehicle speed V2, the target slip speed Vslip * is set so as to smoothly shift from the predetermined speed Vs2 to the predetermined speed Vs3 as the vehicle speed V increases. Here, the predetermined vehicle speed V1 is set as a value in the vicinity of the upper limit of the vehicle speed V considered to be required to ensure the ability to escape from the stack, and is set to, for example, 5 km / h or 10 km / h. The predetermined vehicle speed V2 is set as a value in the vicinity of the lower limit of the vehicle speed that is considered to require consideration of the vehicle stability, and is set to 15 km /, 25 km /, for example. By controlling the motor 22 using the set target slip speed Vslip *, slip speed Vslip, and required torque Td *, that is, the target slip speed Vslip * and the slip speed that change smoothly with respect to the change in the vehicle speed V. By running while controlling the motor 22 based on Vslip, it is possible to suppress sudden changes in the torque output from the motor 22 to the drive wheels 30a and 30b with respect to changes in the vehicle speed V. As a result, it is possible to suppress the driver from feeling uncomfortable and to suppress excessive electric power from being input to and output from the battery 26 due to a sudden change in the driving state of the motor motor 22. Of course, it is possible to suppress the slip speed Vslip from significantly exceeding the target slip speed Vslip *.

  According to the vehicle 20 of the embodiment described above, when the TRC switch 69 is OFF, a relatively large predetermined speed Vs2 is set as the target slip speed Vslip * when the vehicle speed V is less than the predetermined vehicle speed V1, and the vehicle speed V is set to the predetermined vehicle speed. A predetermined speed Vs3 smaller than the predetermined speed Vs2 is set as the target slip speed Vslip * when the vehicle speed V2 is greater than or equal to V1, and when the vehicle speed V is greater than or equal to the predetermined vehicle speed V1 and less than the predetermined vehicle speed V2, the predetermined speed Vs2 and the predetermined speed Vs3 are set. The target slip speed Vslip * is set so as to make a smooth transition, and the torque limit coefficient α based on the slip speed deviation ΔVslip as the deviation between the slip speed Vslip obtained by subtracting the vehicle speed V from the driving wheel speed Vf and the target slip speed Vslip *. The torque that limits the required torque Td * using Since the motor 22 is controlled so as to be output to 30a, 30b, it is possible to suppress a sudden change in the torque output to the drive wheels 30a, 30b as the vehicle speed V changes. As a result, it is possible to suppress the driver from feeling uncomfortable and to suppress excessive power from being input to and output from the battery 26 due to a sudden change in the driving state of the motor 22. Of course, it is possible to suppress the slip speed Vslip from significantly exceeding the target slip speed Vslip *.

  In the electric vehicle 20 of the embodiment, the TRC switch 69 is provided. However, the TRC switch 69 may not be provided. In this case, in consideration of the ability to escape from the stack, the acceleration performance of the vehicle, the stability of the vehicle, etc., the target of FIG. 5 described above is the same as when the TRC switch 69 is off in step S140 of the drive control routine of FIG. The target slip speed Vslip * may be set based on the vehicle speed V using the solid line of the slip speed setting map.

  In the electric vehicle 20 of the embodiment, the larger value of the wheel speeds Vfl and Vfr is set as the driving wheel speed Vf, but the average value of the wheel speeds Vfl and Vfr is set as the driving wheel speed Vf. It may be a thing.

  In the electric vehicle 20 of the embodiment, regardless of the vehicle speed V, the motor 22 outputs a torque that restricts the required torque Td * according to the slip speed deviation ΔVslip, but depending on the vehicle speed V, for example, the vehicle speed V may be When it is equal to or higher than the threshold value Vref, a braking force may be applied from the brakes 40a and 40b in addition to or instead of this. Here, the threshold value Vref is determined according to the specification of the hybrid vehicle 20, and the predetermined vehicle speed V2 is used in the modification. FIG. 6 shows a drive control routine in which a braking force is applied from the brakes 40a and 40b instead of limiting the required torque Td * when the vehicle speed V is equal to or higher than the threshold Vref (predetermined vehicle speed V2). FIG. 7 shows a drive control routine in which a braking force is applied from the brakes 40a and 40b in addition to the limitation. In the drive control routines of FIGS. 6 and 7, the same processes as those of the drive control routine of FIG. 2 are denoted by the same step numbers, and detailed description thereof is omitted. First, the drive control routine of FIG. 6 will be described. In this drive control routine, when the target slip speed Vslip * is set in steps S150 and S160, the vehicle speed V is compared with the threshold value Vref (step S300). When the vehicle speed V is less than the threshold value Vref, the same as the drive control routine of FIG. In addition, the torque limit coefficient α is set based on the slip speed deviation ΔVslip and the torque limit coefficient α is used to limit the required torque Td * to calculate the torque command Tm * of the motor 22 (steps S170 to S190). 22 is controlled (step S200), and the drive control routine is terminated. On the other hand, when the vehicle speed V is greater than or equal to the threshold value Vref in step S300, the brakes 40a and 40b are controlled based on the target slip speed Vslip * and the wheel speeds Vfl and Vfr of the drive wheels 30a and 30b (step S310) and the required torque. Td * is set to the torque command Tm * of the motor 22 (step S320), the motor 22 is controlled by the set torque command Tm * (step S200), and the drive control routine is terminated. Here, the brakes 40a and 40b are controlled by, for example, calculating the drive wheel slip speeds Vlslip and Vrslip of the drive wheels 30a and 30b by subtracting the vehicle speed V from the wheel speeds Vfl and Vfr, and calculating the calculated drive wheel slip speed. This can be done by applying a braking force from the brake so that the drive wheel slip speed becomes the target slip speed Vslip * for the drive wheel that exceeds the target slip speed Vslip * of Vlslip and Vrslip. As described above, when the vehicle speed V is equal to or higher than the threshold value Vref, the required torque Td * is output from the motor 22 and a braking force is applied to the driving wheels whose driving wheel slip speeds Vlslip and Vrslip exceed the target slip speed Vslip *. By doing so, it is possible to output sufficient torque for the drive wheels whose drive wheel slip speeds Vlslip and Vrslip are less than the target slip speed Vslip * among the drive wheels 30a and 30b, and the drive wheel slip speeds Vlslip and Vrslip are the target slip. For drive wheels having a speed Vslip * or higher, the drive wheel slip speed can be made equal to or lower than the target slip speed Vslip *. In addition, in this case, since the braking force is applied to each driving wheel by the brakes 40a and 40b, the driving wheel slip speeds Vlslip, Vslip, of the driving wheels 30a and 30b can be more reliably compared to those that limit the required torque Td *. Vrslip can be made equal to or lower than the target slip speed Vslip *. Now, consider a case where the driver depresses the accelerator pedal 63 greatly from a state where the vehicle speed V is less than the threshold value Vref when the TRC switch 69 is off. At this time, when the vehicle speed V is slightly lower than the threshold value Vref, a relatively large target slip speed Vslip (for example, the predetermined vehicle speed Vs2 described above) is set, and when the vehicle speed V is equal to or higher than the threshold value Vref, a relatively small target slip speed Vslip is set. * If the predetermined vehicle speed Vs3 is set (for example, when the vehicle speed V crosses the threshold value Vref (vehicle speed V), that is, the braking force from the brakes 40a and 40b acts from the limitation of the required torque Td *. When the target slip speed Vslip * is suddenly changed, a large braking force is applied from the brake to the drive wheels having a large degree of slip, so that the wheel speeds Vfl and Vfr of the drive wheels 30a and 30b rapidly increase. In this case, excessive power may be input to the battery 26. That. On the other hand, similarly to the embodiment, by setting the target slip speed Vslip * based on the vehicle speed V using the solid line of the target slip speed setting map of FIG. 5 in step S160, the target slip speed Vslip * is obtained. Since the vehicle speed V changes smoothly with respect to the change in the vehicle speed V, it is possible to suppress a rapid decrease in the wheel speeds Vfl and Vfr of the drive wheels 30a and 30b when the vehicle speed V crosses the threshold value Vref. As a result, it is possible to suppress the driver from feeling uncomfortable and to prevent excessive electric power from being input to the battery 26 when the vehicle speed V crosses the threshold value Vref.

  Next, the drive control routine of FIG. 7 will be described. In this drive control routine, when slip speed deviation ΔVslip is calculated in step S170, torque limiting coefficient α is set based on slip speed deviation ΔVslip and vehicle speed V (step S400), and vehicle speed V is compared with threshold value Vref (step S400). S410) When the vehicle speed V is less than the threshold value Vref, the torque command Tm * of the motor 22 is calculated using the torque limit coefficient α and the required torque Td *, and the motor 22 is controlled (steps S190 and S200). When the vehicle speed V is equal to or higher than the threshold value Vref in step S410, the brakes 40a and 40b are controlled based on the wheel speeds Vfl and Vfr and the target slip speed Vslip * as in the drive control routine of FIG. In step S420, the motor 22 is controlled (steps S190 and S2). 0), and terminates the drive control routine. In the modification, the torque limit coefficient α is stored in the ROM 54 as a torque limit coefficient setting map by experimentally determining in advance a relationship between the slip speed deviation ΔVslip and the vehicle speed V whether or not the threshold value Vref and the torque limit coefficient α. When the slip speed deviation ΔVslip is given, the corresponding torque limit coefficient α is derived and set from the stored map. An example of the torque limit coefficient setting map in this case is shown in FIG. In the figure, the solid line indicates the torque limit coefficient α when the vehicle speed V is less than the threshold value Vref, and the alternate long and short dash line indicates the torque limit coefficient α when the vehicle speed V is greater than or equal to the threshold value Vref. In the figure, the solid line uses the same value as the torque limit coefficient α in the torque limit coefficient setting map of FIG. As shown in the figure, the torque limit coefficient α is set so as to decrease as the slip speed deviation ΔVslip increases, and tends to be larger when the vehicle speed V is equal to or higher than the threshold value Vref than when the vehicle speed V is lower than the threshold value Vref. Set to In this modification, when the vehicle speed V is less than the threshold value Vref using the torque limit coefficient α set in this way, the slip speed Vslip greatly exceeds the target slip speed Vslip * due to the restriction of the required torque Td *. When the vehicle speed V is equal to or higher than the threshold value Vref, the slip speed Vslip greatly exceeds the target slip speed Vslip * due to the restriction of the required torque Td * and the action of the braking force from the brake to the drive wheels having a large degree of slip. Can be suppressed. Similar to the drive control routine of FIG. 6, when the TRC switch is off, it is possible to suppress the driver from feeling uncomfortable and the vehicle speed V crosses the threshold value Vref from a state where the vehicle speed V is less than the threshold value Vref. At this time, it is possible to prevent excessive electric power from being input to the battery 26. In the modification, the threshold value Vref uses the predetermined vehicle speed V2, but a value slightly larger or slightly smaller than the predetermined vehicle speed V2 may be used.

  In the electric vehicle 20 of the embodiment, the hydraulic brakes 40a, 40b, 40c, and 40d are used to apply the braking force to the drive wheels 30a and 30b and the non-drive wheels 32a and 32b. It is also possible to use a brake that operates according to the above.

  In the embodiment, the electric vehicle 20 including the motor 22 as a drive source capable of outputting power to the drive wheels 30a and 30b has been described. However, in addition to the motor 22, as shown in the electric vehicle 120 of a modified example of FIG. The present invention may be applied to the electric vehicle 120 in which the engine 122 and the motor 124 are connected to the drive shaft 28 connected to the drive wheels 30a and 30b via the planetary gear mechanism 126, or the electric vehicle 220 of the modified example of FIG. As shown, the engine 222 has an inner rotor 232 connected to the crankshaft of the engine 222 and an outer rotor 234 connected to the drive shaft 32 that outputs power to the drive wheels 30a and 30b. An electric motor provided with a counter-rotor motor 230 that transmits a part of the power to the drive shaft 32 and converts the remaining power into electric power. It may alternatively be applied to the vehicle 220. Moreover, it is good also as what applies to the motor vehicle provided only with an engine as a drive source which can output motive power to a drive wheel.

  In the embodiment, the electric vehicle 20 including the motor 22 capable of outputting power to the drive wheels 30a and 30b has been described. However, the electric vehicle 20 may be applied to a vehicle other than the vehicle.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 which is one Example of this invention. It is a flowchart which shows an example of the drive control routine performed by the main electronic control unit 50 of an Example. It is explanatory drawing which shows an example of the map for request | requirement torque setting. It is explanatory drawing which shows an example of the map for torque limitation coefficient setting. It is explanatory drawing which shows an example of the map for target slip speed setting. It is a flowchart which shows an example of the drive control routine of a modification. It is a flowchart which shows an example of the drive control routine of a modification. It is explanatory drawing which shows an example of the map for torque limitation coefficient setting of a modification. It is a block diagram which shows the outline of a structure of the electric vehicle 120 of a modification. It is a block diagram which shows the outline of a structure of the electric vehicle 220 of a modification.

Explanation of symbols

  20, 120, 220 Electric vehicle, 22 Motor, 24 Inverter, 26 Battery, 28 Drive shaft, 30a, 30b Drive wheel, 31 Differential gear, 32a, 32b Non-drive wheel, 34a, 34b, 34c, 34d Wheel speed sensor, 40a , 40b, 40c, 40d Brake, 50 main electronic control unit, 52 CPU, 54 ROM, 56 RAM, 61 shift lever, 62 shift position sensor, 63 accelerator pedal, 64 accelerator pedal position sensor, 65 brake pedal, 66 brake pedal position Sensor, 68 vehicle speed sensor, 69 TRC switch, 122 engine, 124 motor, 126 planetary gear mechanism, 230 rotor motor, 232 inner rotor, 234 outer rotor.

Claims (10)

A vehicle including a drive source capable of outputting a driving force to a drive wheel,
Vehicle speed detection means for detecting the vehicle speed;
Wheel speed detection means for detecting a wheel speed that is at least the rotational speed of the drive wheel;
Slip speed calculating means for calculating a slip speed as a degree of slip of the drive wheel based on the detected vehicle speed and the detected wheel speed;
When the detected vehicle speed is less than the first vehicle speed, the drive source is controlled so that the calculated slip speed is within a first allowable range, and the detected vehicle speed is greater than the first vehicle speed. When the vehicle speed is equal to or higher than 2, the drive source is controlled so that the calculated slip speed is within a second allowable range different from the first allowable range, and the detected vehicle speed is equal to or higher than the first vehicle speed. When the speed is less than the second vehicle speed, the drive source is controlled so that the calculated slip speed is within the transition allowable range for smoothly shifting between the first allowable range and the second allowable range. Control means to
A vehicle comprising:   The vehicle according to claim 1, wherein the second allowable range is a range in which the calculated slip speed is more limited than the first allowable range. The vehicle according to claim 1 or 2,
Provided with a required driving force setting means for setting a required driving force for traveling,
The control means sets a first speed within the first allowable range as a target slip speed when the detected vehicle speed is less than the first vehicle speed, and the detected vehicle speed is the second vehicle speed. In the above case, a second speed within the second allowable range is set as the target slip speed, and when the detected vehicle speed is equal to or higher than the first vehicle speed and lower than the second vehicle speed, the transition allowable range is set. A transition speed for smoothly transitioning between the first speed and the second speed is set as the target slip speed, and based on the calculated slip speed and the set target slip speed A vehicle that controls to output a driving force that limits the set required driving force using a driving force limit that is set.   The control means sets a predetermined value as the driving force limit when the calculated slip speed is equal to the set target slip speed, and when the calculated slip speed is smaller than the set target slip speed, The driving force limit is set such that the greater the deviation between the speed and the target slip speed is, the smaller the degree of limiting the set required driving force is compared to the predetermined value. When it is larger than the set target slip speed, the greater the deviation between the slip speed and the target slip speed, the greater the degree of limiting the set required drive force compared to the predetermined value. The vehicle according to claim 3, which is means for setting The vehicle according to any one of claims 1 to 4,
The drive source comprises an electric motor capable of outputting a driving force,
A vehicle comprising power storage means capable of exchanging electric power with the drive source. The vehicle according to any one of claims 1 to 4,
The drive source is connected to an internal combustion engine, an output shaft of the internal combustion engine, and a drive shaft connected to the drive wheel, and drives at least part of the power from the internal combustion engine with input and output of electric power and power. Power power input / output means for outputting to the shaft, and an electric motor capable of inputting / outputting power to the drive shaft,
A vehicle comprising power storage means capable of exchanging electric power with the drive source. The drive source includes a drive circuit that drives the electric motor,
The first allowable range and / or the second allowable range is a range set based on at least one of a rating of the electric motor, a capacity of the drive circuit, and a capacity of the power storage unit. 5. The vehicle according to 5 or 6. A vehicle according to any one of claims 1 to 7,
An allowable range change switch for changing an allowable range for allowing the calculated slip speed by a driver's operation;
When the allowable range change switch is off, the control means is within the third allowable range in which the calculated slip speed is limited from the second allowable range regardless of the detected vehicle speed. When the allowable range change switch is ON, the calculated slip speed is within the first allowable range or the second allowable range or the transition based on the detected vehicle speed. A vehicle that is means for controlling the drive source so as to be within an allowable range. The vehicle according to any one of claims 1 to 8,
A braking force applying means capable of applying a braking force to the drive wheel;
The control means is means for controlling the drive source and the braking force applying means when the detected vehicle speed is equal to or higher than the second vehicle speed. A vehicle control method including a drive source capable of outputting a driving force to a drive wheel,
(A) calculating a slip speed as a degree of slip of the drive wheel based on a vehicle speed and at least a wheel speed which is a rotation speed of the drive wheel;
(B) When the vehicle speed is less than the first vehicle speed, the drive source is controlled so that the calculated slip speed is within a first allowable range, and the second vehicle speed is greater than the first vehicle speed. In this case, the drive source is controlled so that the calculated slip speed is within a second allowable range different from the first allowable range, and the detected vehicle speed is equal to or higher than the first vehicle speed. When the vehicle speed is less than 2, the drive source is controlled so that the calculated slip speed is within a transition allowable range for smoothly shifting between the first allowable range and the second allowable range. Control method.

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