JP2016084110A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress erroneous determination of slippage.SOLUTION: When a brake pedal is tuned on from off during travel, a lower limit guard value Vslmin is decreased to a value N2 (time T21-T22), and then when the brake pedal is turned off from on with an estimated slip speed Vslest increasing to a given speed Vsref or higher, the lower limit guard value Vslmin is increased to a value N1 (time T25 and thereafter). This enables suppression of an event of the estimated slip speed Vslest being deviated from an actual slip speed Vslre, thus suppressing an erroneous determination of slippage despite that no slip has actually occurred when a drive wheel has gripped after locking.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a vehicle control device, and more particularly, is installed in a vehicle and estimates a slip speed based on a drive wheel speed and a vehicle body speed, which are rotational speeds of drive wheels, and the estimated slip speed is expressed by a lower limit card value. The present invention relates to a vehicle control device to be restricted.

  Conventionally, this type of vehicle control device controls the motor so that the motor drive is limited when the slip speed obtained by subtracting the estimated vehicle speed obtained by the integral calculation from the drive wheel speed is equal to or greater than a threshold value. Has been proposed (see, for example, Patent Document 1). In this device, a temporary slip speed obtained by setting a slip speed limit value based on the shift position and the elapsed time t after the shift position is changed, and subtracting the estimated vehicle body speed obtained by integral calculation from the driving wheel speed. Is set as a slip speed by limiting the slip speed to a slip speed limit value, thereby preventing the slip speed from becoming a value that cannot normally be taken with respect to the shift position, thereby preventing the slip from being erroneously determined.

JP 2008-111351 A

  In the above-described vehicle control device, when the brake is released after the driving wheel is locked by sudden braking, the slip speed set by calculation deviates from the actual slip speed, and the calculated slip speed becomes equal to or greater than the determination value. In some cases, it is erroneously determined that a slip has occurred even though it has not actually slipped. The driving wheel speed becomes 0 when the driving wheel is locked, and approaches the vehicle speed from 0 when the driving wheel is gripped by releasing the brake. The actual slip speed becomes a negative value due to the lock of the drive wheel, and approaches a value 0 from the negative value due to the grip of the drive wheel. On the other hand, the calculated slip speed becomes a negative value in the same manner due to the lock of the driving wheel. However, when the slip speed is limited by the slip speed limit value, the calculated slip speed becomes a value higher than the actual slip speed and deviates from the actual slip speed. End up. In order to suppress such divergence, the slip speed limit value is decreased by sudden braking and the slip speed limit value is increased by turning off the brake, thereby suppressing the calculated slip speed from being limited by the slip speed limit value. Processing is in progress. By the way, when traveling on a road surface with a low coefficient of friction, it may take a relatively long time for the drive wheels to grip after the brake is released. At this time, if the slip speed limit value is quickly increased by turning off the brake, the calculated slip speed is limited by the slip speed limit value and increases as the slip speed limit value increases. After that, when the driving wheel grips, the calculated slip speed increases from the value, so that it is erroneously determined that the vehicle is slipping although it is not actually slipping.

  The vehicle control device of the present invention is mainly intended to suppress erroneous determination of slip.

  The vehicle control apparatus of the present invention employs the following means in order to achieve the main object described above.

The vehicle control apparatus according to the present invention includes:
A vehicle control device that is mounted on a vehicle, estimates a slip speed based on a drive wheel speed and a vehicle body speed, which are rotation speeds of drive wheels, and limits the estimated slip speed by a lower limit card value,
The lower limit guard value is decreased when the brake is turned on during running, and then the lower limit guard value is increased after the brake is turned off and the estimated slip speed exceeds a predetermined value. The lower limit guard value changing means is provided.

  In the vehicle control device of the present invention, the slip speed is estimated based on the drive wheel speed, which is the rotational speed of the drive wheel, and the vehicle body speed, and the estimated slip speed is limited by the lower limit card value. When the brake is turned on from the off state, the lower limit guard value is lowered. Thereby, it can suppress that the estimated slip speed is restrict | limited by a lower limit guard value. Thereafter, the lower guard value is increased after the brake is turned off and the estimated slip speed becomes equal to or higher than a predetermined value. If it takes a relatively long time for the drive wheels to grip after the brake is turned off, such as when driving on a road surface with a low coefficient of friction, the estimated slip will be increased if the lower guard value is increased immediately after the brake is turned off. The speed increases by being limited to the lower limit guard value, and it may be erroneously determined that the slip has become a value higher than the actual slip speed, but the brake is turned off and the estimated slip speed is By increasing the lower limit guard value after the predetermined value or more, the estimated slip speed is prevented from being limited by the lower limit guard value. Thereby, it can suppress that the estimated slip speed becomes higher than an actual slip speed, and can suppress the erroneous determination of slip. Here, as the “predetermined value”, the lower limit guard value is increased when the estimated slip speed exceeds a predetermined value in consideration of the increase rate of the lower limit guard value and the increase rate of the estimated slip speed. In this case, the lower limit guard value is set to a value that does not become higher than the estimated slip speed.

  In such a vehicle control apparatus of the present invention, there is provided a slip determination means for determining that the drive wheel is slipping when a value obtained by limiting the estimated slip speed with the lower limit guard value is equal to or greater than a slip determination threshold. It can also be.

  Further, in the vehicle control device of the present invention, the lower limit guard value changing means lowers the lower limit guard value when the brake is turned on during running when an abnormality in which the driving wheel speed cannot be detected occurs. Thereafter, the lower limit guard value may be increased after the brake is turned off and the estimated slip speed becomes equal to or higher than the predetermined value.

1 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 20 as an embodiment of the present invention. 5 is a flowchart showing an example of a lower limit guard value setting routine executed by an HVECU 70. FIG. 6 is an explanatory diagram showing an example of time changes of a vehicle speed, a driving wheel speed, a depression amount of a brake pedal 85, a lower limit guard value Vslmin, an actual slip speed Vslre that is an actual slip speed, and an estimated slip speed Vslest in a hybrid vehicle of a comparative example. is there. It is explanatory drawing which shows an example of the time change of the vehicle body speed in the hybrid vehicle 20 of an Example, driving wheel speed, the depression amount of the brake pedal 85, the lower limit guard value Vslmin, the actual slip speed Vslre, and the estimated slip speed Vslest.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 as an embodiment of the present invention. As shown in the figure, the hybrid vehicle 20 of the embodiment includes an engine 22, an engine electronic control unit (hereinafter referred to as "engine ECU") 24, a planetary gear 30, motors MG1, MG2, a battery 50, and a motor. An electronic control unit (hereinafter referred to as “motor ECU”) 40, a battery electronic control unit (hereinafter referred to as “battery ECU”) 52, an electronic control brake system (hereinafter referred to as ECB) 94, and the entire vehicle are controlled. And a hybrid electronic control unit (hereinafter referred to as “HVECU”) 70.

  The engine 22 is configured as an engine that can output power using a hydrocarbon-based fuel such as gasoline or light oil, and the operation is controlled by the engine ECU 24.

  Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The engine ECU 24 receives signals from various sensors necessary for controlling the operation of the engine 22 via an input port, and the engine ECU 24 outputs various control signals for controlling the operation of the engine 22. It is output through the port. The engine ECU 24 calculates the rotational speed Ne of the engine 22 based on a signal from a crank position sensor attached to the crankshaft 26 of the engine 22.

  In the planetary gear 30, a carrier is connected to the crankshaft 26 of the engine 22, and a ring gear is connected to a drive shaft 36 that is connected to drive wheels 38 a and 38 b that are front wheels via a differential gear 37.

  Each of the motors MG1 and MG2 is configured as a known synchronous generator motor including a rotor in which a permanent magnet is embedded and a stator in which a three-phase coil is wound. Motor MG1 has a rotor (rotating shaft) connected to the sun gear of planetary gear 30, and motor MG2 has a rotor (rotating shaft) connected to drive shaft 36. Motors MG1, MG2 are driven by inverters 41, 42 controlled by motor EUC40.

  Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The motor ECU 40 includes signals from various sensors necessary to drive and control the motors MG1 and MG2, for example, the rotors of the motors MG1 and MG2 from the rotational position sensor that detects the rotational position of the rotors of the motors MG1 and MG2. Rotation positions θm1 and θm2 and phase currents flowing in the phases of the motors MG1 and MG2 from a current sensor (not shown) are input via an input port, and switching elements (not shown) of inverters 41 and 42 are input from the motor ECU 40. A switching control signal or the like is output through the output port. The motor ECU 40 calculates the rotational speeds Nm1, Nm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2 from the rotational position sensor.

  The battery 50 is configured as a lithium ion secondary battery, for example, and exchanges electric power with the motors MG1 and MG2 via the inverters 41 and 42. The battery 50 is managed by the battery ECU 52.

  Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The battery ECU 52 includes signals from various sensors necessary for managing the battery 50, for example, a battery voltage Vb from a voltage sensor installed between terminals of the battery 50 and a current sensor attached to an output terminal of the battery 50. Battery current Ib (a positive value when discharging from the battery 50), a battery temperature Tb from a temperature sensor (not shown) attached to the battery 50, and the like are input via the input port. In order to manage the battery 50, the battery ECU 52 is a power storage that is a ratio of the capacity of electric power that can be discharged from the battery 50 at that time based on the integrated value of the battery current Ib of the battery 50 detected by the current sensor. The ratio SOC is calculated, and the input / output limits Win and Wout, which are allowable input / output powers that may charge / discharge the battery 50, are calculated based on the calculated storage ratio SOC and the battery temperature Tb from the temperature sensor. ing.

  The ECB 94 is a brake that supplies adjusted hydraulic pressure to a brake master cylinder 96 that generates hydraulic pressure (brake master pressure) in response to depression of the brake pedal 85, and to brake wheel cylinders (not shown) of the drive wheels 38a and 38b and the driven wheels 38c and 38d. An actuator 97 and an ECB electronic control unit (hereinafter referred to as ECBECU) 99 for controlling the brake actuator 97 are provided. The brake actuator 97 is configured so that the braking torque corresponding to the share of the brake in the braking force applied to the vehicle by the brake master pressure and the rotation speed Nm2 of the motor MG2 is applied to the driving wheels 38a and 38b and the driven wheels 38c and 38d. The hydraulic pressure of the brake wheel cylinder is adjusted, and the hydraulic pressure of each brake wheel cylinder is adjusted so that the braking torque acts on the drive wheels 38a, 38b and the driven wheels 38c, 38d regardless of the brake master pressure.

  The ECBECU 99 inputs signals such as wheel speeds Vdr, Vdl, Vnr, Vnl from a wheel speed sensor 98a to 98d attached to the drive wheels 38a, 38b and driven wheels 38c, 38d, and a steering angle from a steering angle sensor (not shown). Then, when the driver depresses the brake pedal 85, the anti-lock brake system (ABS) control for preventing any of the driving wheels 38a, 38b and the driven wheels 38c, 38d from slipping due to the lock or the driver's accelerator A traction control (TRC) that prevents any of the driving wheels 38a, 38b and the driven wheels 38c, 38d from slipping due to idling when the pedal 83 is depressed, and an attitude that maintains the attitude when the vehicle is turning. Vehicle behavior stabilization control such as holding control (VSC) is performed. The ECBECU 99 communicates with the HVECU 70 and controls the drive of the brake actuator 97 by a control signal from the HVECU 70, and if necessary, the wheel speeds Vdr, Vdl, Vnr, Vnl from the wheel speed sensors 98a to 98d, not shown. A signal such as a steering angle from the steering angle sensor is input, and data relating to the state of the brake actuator is output to the HVECU 70.

  Although not shown, the HVECU 70 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. The HVECU 70 includes an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the operation position of the shift lever 81, and an accelerator opening from the accelerator pedal position sensor 84 that detects the amount of depression of the accelerator pedal 83. Acc, the brake pedal position BP from the brake pedal position sensor 86 that detects the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 88, and the like are input via the input port. The HVECU 70 is communicably connected to the engine ECU 24, the motor ECU 40, the battery ECU 52, and the ECBECU 99, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, the battery ECU 52, and the ECBECU 99. The shift position SP includes a parking range (P range) used during parking, a reverse range for reverse travel (R range), a neutral neutral range (N range), and a normal drive range for forward travel (D range). In addition, the setting of the driving force when the accelerator is on is the same as the D range, but there is a brake range (B range) in which the braking force applied to the vehicle when the accelerator is off during traveling is set to be larger than the D range. ing.

  In the hybrid vehicle 20 of the embodiment configured as described above, a hybrid travel mode (HV travel mode) that travels with the operation of the engine 22 or an electric travel mode (EV travel mode) that travels while the operation of the engine 22 is stopped. Run.

  When traveling in the HV traveling mode, the HVECU 70 requires the required torque Tr * required for traveling based on the accelerator opening Acc and the vehicle speed V (a positive value when traveling forward) (a positive value when traveling forward). ) Is set. Subsequently, the set required torque Tr * is multiplied by the rotational speed Nr of the drive shaft 36 (for example, the rotational speed Nm2 of the motor MG2 (a positive value when traveling forward)) to obtain the traveling power Pdrv * required for traveling. The required power required for the vehicle is calculated by subtracting the calculated charge / discharge required power Pb * of the battery 50 based on the storage ratio SOC of the battery 50 (a positive value when discharging from the battery 50) from the calculated traveling power Pdrv *. Set Pe *. Then, the target rotational speed Ne * and the target torque Te * of the engine 22 are set using the required power Pe * and an operation line (for example, an optimum fuel efficiency operation line) for operating the engine 22 efficiently. A torque command Tm1 * as a torque to be output from the motor MG1 is set by the rotational speed feedback control so that the rotational speed Ne of the engine 22 becomes the target rotational speed Ne * within the range of the input / output limits Win and Wout. At the same time, when the motor MG1 is driven with the torque command Tm1 *, the torque acting on the drive shaft 36 via the planetary gear 30 is subtracted from the required torque Tr * to set the torque command Tm2 * of the motor MG2, and the set target rotational speed Ne * and target torque Te * are transmitted to the engine ECU 24, and torque commands Tm1 *, T 2 * For be sent to the motor ECU40. The engine ECU 24 that has received the target rotational speed Ne * and the target torque Te *, controls the intake air amount, fuel injection control, and ignition of the engine 22 so that the engine 22 is operated by the target rotational speed Ne * and the target torque Te *. The motor ECU 40 that performs control or the like and receives the torque commands Tm1 * and Tm2 * performs switching control of the switching elements of the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1 * and Tm2 *. By such control, it is possible to travel while outputting the required torque Tr * to the drive shaft 36 within the range of the input / output limits Win and Wout of the battery 50 while operating the engine 22 efficiently. In this HV traveling mode, the stop condition of the engine 22 is satisfied, for example, when the required power Pe * is equal to or lower than the stop threshold value Pstop defined as the upper limit of the range of the required power Pe * that should be stopped. Sometimes, the operation of the engine 22 is stopped and the EV traveling mode is entered.

  During travel in the EV travel mode, the HVECU 70 sets a required torque Tr * to be output to the drive shaft 36 based on the accelerator opening Acc and the vehicle speed V, and sets a value 0 to the torque command Tm1 * of the motor MG1. At the same time, the torque command Tm2 * of the motor MG2 is set and transmitted to the motor ECU 40 so that the required torque Tr * is output to the drive shaft 36 within the range of the input / output limits Win and Wout of the battery 50. Then, the motor ECU 40 that receives the torque commands Tm1 * and Tm2 * performs switching control of the switching elements of the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1 * and Tm2 *. With such control, the engine 22 can travel by outputting the required torque Tr * to the drive shaft 36 within the range of the input / output limits Win and Wout of the battery 50 with the engine 22 stopped. In this motor operation mode, when the required power Pe * calculated in the same manner as in the HV traveling mode reaches a starting threshold value Pstart determined as the lower limit of the range of the required power Pe * that is better to start the engine 22, the engine When the starting condition 22 is satisfied, the engine 22 is started and the mode is shifted to the HV traveling mode.

  The HVECU 70 of the hybrid vehicle 20 according to the embodiment normally uses the ABS by using the slip speed obtained by subtracting the vehicle speed V from the vehicle speed sensor 88 from each of the wheel speeds Vdr, Vdl, Vnr, Vnl from the wheel speed sensors 98a to 93d. Control, TRC control, and VSC control are performed.

  When ABS control or TRC control cannot be performed, such as when an abnormality occurs in the wheel speed sensors 98a to 98d or communication between the ECBECU 99 and the HVECU 70 is interrupted, a differential value dVsl of the estimated slip speed Vslest is calculated by the following equation (1). Then, using the estimated slip speed (previous Vslest), the conversion coefficient K1 and the differential value dVsl that have already been set, a temporary estimated slip speed Vstmp, which is a provisional value of the estimated slip speed, is calculated by the following equation (2). Then, the estimated slip speed Vsltmp calculated by the following equation (3) is limited to the upper limit guard value Vslmax and the lower limit guard value Vslmin, which are upper and lower limit values that the slip speed can normally take, and is set as the estimated slip speed Vslest. In equation (1), Gr is the gear ratio of the differential gear 37, M is the vehicle weight, R is the drive wheel radius, Ip is the inertia moment of the drive wheels 38a and 38b, ωp is the calculated drive wheel angular velocity, and Tp is the drive torque ( (The sum of the torque acting on the drive shaft 36 via the planetary gear 30 and the torque command Tm2 *) when the motor MG1 is driven with the torque command Tm1 *. It was assumed that the conversion factor was obtained in The driving wheels 38a and 38b have the same driving wheel radius and moment of inertia, and the driving wheel angular velocity ωp is calculated using the amount of change in the rotational speed Nm2 of the motor MG2. Equations (1) and (2) can be obtained from the integral calculation for the slip speed Vs in the following equation (4) derived from the equation of motion of the entire vehicle and the equations of motion of the drive wheels 38a and 38b.

dVsl = Gr / (M ・ R) ・ ((M ・ R ² ) / Gr ² + Ip) ・ (dωp / dt)-Tp) (1)
Vsltmp = last time Vslest + K1 ・ dVsl ... (2)
Vslest = min (Vslmax, max (Vsltmp, Vslmin)) (3)
Vs (t) = Gr / (M ・ R) ・ ∫ [((M ・ R ² ) / Gr ² + Ip) dωp / dt − Tp)] dt (4)

  When the slip speed Vs and the estimated slip speed Vsleth set in this way are equal to or higher than the slip determination threshold Vslref, it is determined that the drive wheels 38a and 38b are slipping, and a torque limit is imposed on the required torque Tr * to impose a drive limit. The engine multiplied by the coefficient α (α is a positive value smaller than 1) is reset to the required torque Tr *, and the engine is set to run in the above-described HV driving mode or EV driving mode with the reset required torque Tr *. 22 and motors MG1 and MG2 are controlled. With such control, when an abnormality occurs in the wheel speed sensors 98a to 98d or communication between the ECBECU 99 and the HVECU 70 is interrupted, the torque output to the drive shaft 36 is reduced when any of the drive wheels 38a and 38b slips due to idling. Thus, slip can be suppressed.

  Next, the operation of the hybrid vehicle 20 of the embodiment thus configured, particularly when the drive wheels 38a and 38b are locked in a state where the wheel speed sensors 98a to 98d are abnormal or the communication between the ECBECU 99 and the HVECU 70 is interrupted. An operation when setting the lower limit guard value Vslmin will be described. FIG. 2 is a flowchart showing an example of a lower limit guard value setting routine executed by the HVECU 70. This routine is repeatedly executed every predetermined time when an abnormality occurs in the wheel speed sensors 98a to 98d or communication between the ECBECU 99 and the HVECU 70 is interrupted.

  When the lower limit guard value setting routine is executed, the HVECU 70 executes a process for checking whether or not the lower limit guard value lowering start condition is satisfied (step S100). Here, the lower limit guard value lowering process, which will be described later, is not executed when the routine is executed last time (first start condition), the vehicle is traveling (second start condition), and the brake pedal 85 is large. The lower limit guard value lowering start condition is satisfied when all of the three conditions of being depressed (third start condition) are satisfied. In the embodiment, when the drive wheels 38a and 38b are rotating when the shift position SP is in the D range or the B range, or when the drive wheels 38a and 38b are rotating when the shift position SP is in the R range. In addition, it is assumed that the vehicle is traveling. Since it is considered that the wheel speed sensors 98a to 98d are abnormal or the communication between the ECBECU 99 and the HVECU 70 is interrupted, the rotation of the drive wheels 38a and 38b calculated from the rotation speed Nm2 of the motor MG2 is considered. The drive wheels 38a and 38b are rotating when the number is larger than 0. Further, it is assumed that the brake pedal 85 is largely depressed when the depression amount of the brake pedal 85 is equal to or greater than the first depression amount. Here, the first depression amount is a predetermined value as a lower limit value of the depression amount that can be determined that the brake pedal 85 is largely depressed and the brake is turned on. For example, 85%, 90%, 95%, etc. Suppose that That is, the third start condition is that the brake is on.

When the lower limit guard value lowering start condition is satisfied, the lower limit guard value lowering process for lowering the lower limit guard value Vslmin is started (step S110), and this routine is finished. Here, the lower limit guard value lowering process sets the speed in the traveling direction to a positive value, and decreases the lower limit guard value Vslmin from the value N1 to a value N2 that is smaller than the value N1 at the change rate Rvsl with time. Then, as will be described later, the lower limit guard value Vslmin is held at the value N2 until the lower limit guard value lowering process is canceled. The value N1 is a predetermined value as a lower limit value of the slip speed that can be normally taken when the drive wheels 38a and 38b are not locked, and for example, 0 km / s, -3 km / s, and -5 km / s are used. Can do. Further, the value N2 is a value determined in advance as a value smaller than the lower limit value of the slip speed that can be taken when the brake pedal 85 is depressed and the drive wheels 38a and 38b are locked when the ABS control is not performed. For example, −15 m / s, −20 m / s, and −25 m / s can be used. Furthermore, the change rate Rvsl is a predetermined value as a rate of sharp change, and for example, 80 m / s ² , 100 m / s ² , and 120 m / s ² can be used. By executing the lower limit guard value lowering process in this way, the estimated slip speed Vslip is less likely to be limited by the lower limit guard value Vslmin. The reason why the lower limit guard value Vslmin is lowered in this way is to prevent the estimated slip speed Vslip from deviating from the actual slip speed by limiting the estimated slip speed Vslip to the lower limit guard value Vslmin.

  When the lower limit guard value decrease start condition is not satisfied, for example, when the lower limit guard value decrease process is already executed, when the vehicle is stopped, or when the depression amount of the brake pedal 85 is small (step S100), the lower limit It is checked whether or not the guard value lowering process cancellation condition is satisfied (step S120). Here, the depression of the brake pedal 85 is small (first release condition), the estimated slip speed Vslip is equal to or higher than the predetermined speed Vsref (second release condition), and the lower limit guard value lowering process is started. The lower limit guard lowering process release condition is satisfied when all of the three conditions that the predetermined time (for example, 1.0 sec, 1.5 sec, 2.0 sec, etc.) has passed (the third release condition) are satisfied. Was established. In the embodiment, when the depression amount of the brake pedal 85 is less than the second depression amount, the depression of the brake pedal 85 is small. Here, the second depression amount is a predetermined value as an upper limit value of the depression amount that can be determined that the brake pedal 85 is turned off, and is, for example, 5%, 10%, 15%, or the like. That is, the first release condition is that the brake pedal 85 is turned off. In the second release condition, the predetermined speed Vsref is estimated in consideration of a later-described change rate Rvsl when the lower limit guard value Vslmin is increased and an increase rate of the estimated slip speed Vslip obtained in advance through experiments and analysis. The estimated slip speed Vslip is predetermined as a value that is not limited to the lower limit guard even when the lower limit guard value Vslmin is increased at the timing when the slip speed Vslip becomes equal to or higher than the predetermined speed Vsref.

  When the lower limit guard value lowering process release condition is not satisfied (step S120), this routine ends. Thereby, when the lower limit guard value lowering process has already been executed, the lower limit guard value lowering process is continued, and when the lower limit guard value lowering process is not executed, this routine is ended as it is.

  When the lower limit guard value lowering process cancellation condition is satisfied (step S120), the lower limit guard value lowering process is canceled (step S130), and this routine is terminated. When the lower limit guard value lowering process is canceled, the lower limit guard value Vslmin is increased to the value N1 at the change rate Rvsl with the passage of time. The reason for setting the lower limit guard value Vslmin in this way will be described.

  FIG. 3 shows an example of changes over time in the vehicle speed, the driving wheel speed, the depression amount of the brake pedal 85, the lower limit guard value Vslmin, the actual slip speed Vslre, which is the actual slip speed, and the estimated slip speed Vslest in a hybrid vehicle as a comparative example. FIG. 4 is an explanatory diagram showing the vehicle speed, the driving wheel speed, the depression amount of the brake pedal 85, the lower limit guard value Vslmin, the actual slip speed Vslre, and the estimated slip speed Vslest in the hybrid vehicle 20 of the embodiment. It is explanatory drawing shown. In the figure, the driving wheel speed, the depression amount of the brake pedal 85, and the estimated slip speed Vslest are indicated by a solid line, the actual slip speed Vslre is indicated by a one-dot chain line, and the vehicle body speed and the lower limit guard value Vslmin are indicated by a broken line. In the comparative example, a case is considered in which the lower limit guard value Vslmin is increased and the temporary slip speed Vsltmp is limited until the drive wheels 38a and 38b grip after the brake pedal 85 is turned off.

  As shown in FIGS. 3 and 4, when the brake pedal 85 is depressed during travel (time T11, T21), if the driving wheels 38a and 38b are locked, the driving wheel speed becomes close to the value 0, so that the actual slip speed Vslre Decreases from 0 to a negative value (time T12, T22). After that, when the brake is turned off (time T13, T23) and the driving wheels 38a, 38b are gripped (time T14, T24), the driving wheel speed increases and approaches the vehicle body speed, so the actual slip speed Vslre increases. Thus, the negative value is changed to 0 (time T15, T25). When a certain amount of time is required from when the brake pedal 85 is turned off to when the drive wheels 38a and 38b are gripped, such as when running on a road surface with a low friction coefficient (for example, a frozen road surface), the actual slip speed Vslre Is maintained at a negative value for a while after the brake pedal 85 is turned off (time T13 to T14, T23 to T24), and increases to 0 when the driving wheels 38a and 38b are gripped (time T14 to T15). , T24-T26).

  By the way, the estimated slip speed Vslest is a value obtained by limiting the temporary slip speed Vsltmp with upper and lower limit guard values Vslmax and Vslmin. Therefore, the lower limit guard value between the time when the brake pedal 85 is turned off and the driving wheels 38a and 38b grip. When Vslmin increases and the temporary slip speed Vsltmp is limited, as shown in FIG. 3, the estimated slip speed Vslest increases with the lower limit guard value Vslmin (time T13 to T14). When the drive wheels 38a and 38b grip in such a state (time T14), the estimated slip speed Vsltmp increases from the lower limit guard value Vslmin to become the slip determination threshold Vslref or more, although the actual slip speed Vslre is close to the value 0. It is erroneously estimated that slip has occurred.

  In the embodiment, as shown in FIGS. 2 and 4, when the brake pedal 85 is turned on during running, the lower limit guard value lowering process is started and the lower limit guard value Vslmin is decreased to the value N2 at the change rate Rvsl. Thereafter, the lower limit guard value Vslmin is maintained at the value N2 until the estimated slip speed Vslest becomes equal to or higher than the predetermined speed Vsref by turning off the brake pedal 85 (steps S100 to S120 in FIG. 2, time T21 to FIG. 4). T25). When the estimated slip speed Vslest becomes equal to or higher than the predetermined speed Vsref, the lower limit guard value lowering process is canceled and the lower limit guard value Vslmin is increased to the value N1 at the change rate Rvsl (steps S120 and S130 in FIG. 2 and FIG. 4). Time T25 to T26). This prevents the temporary slip speed Vsltmp from being limited by the lower limit guard value Vslmin and increasing the estimated slip speed Vslest after the brake pedal 85 is turned off until the drive wheels 38a and 38b grip. It is possible to suppress erroneous determination that slip has occurred even though the actual slip speed Vslre is near zero.

  According to the hybrid vehicle 20 of the embodiment described above, the lower limit guard value Vslmin is decreased to the value N2 at the change rate Rvsl when the brake pedal 85 is turned on during running, and then the brake pedal 85 is turned off from on. When the estimated slip speed Vslest exceeds the predetermined speed Vsref, the lower limit guard value Vslmin is increased to the value N1 at the change rate Rvsl, so that the temporary slip speed Vsltmp is obtained when the locked drive wheels 38a and 38b are gripped. Is limited by the lower limit guard value Vslmin, and it is possible to suppress the estimated slip speed Vslest from being increased, and it is possible to suppress erroneous determination that a slip has occurred even though the slip has not actually occurred.

  In the embodiment, the case where the present invention is applied to a hybrid vehicle that drives the driving wheels 38a and 38b, which are front wheels, is illustrated. However, the present invention can also be applied to a hybrid vehicle that drives the rear wheels. In this case, the second start condition of the process in step S100 is that the rear wheel rotates when the shift position SP is in the D range or the B range and the rear wheel rotates or when the shift position SP is in the R range. It can be assumed that the vehicle is running when the vehicle is running. The present invention can also be applied to a hybrid vehicle that further includes a rear wheel motor that outputs power to the rear wheels and drives the front wheels and the rear wheels. In this case, the second start condition of the process of step S100 may be that the vehicle is traveling when the front wheel or the rear wheel is rotating when the shift position SP is in the D range or the B range.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the HVECU 70 corresponds to “lower limit guard value changing means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. In other words, the interpretation of the invention described in the column of means for solving the problem should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problem. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of vehicle control devices.

  20 hybrid vehicle, 22 engine, 24 electronic control unit (engine ECU) for engine, 26 crankshaft, 30 planetary gear, 36 drive shaft, 37 differential gear, 38a, 38b drive wheel, 38c, 38d driven wheel, 40 electronic control for motor Unit (motor ECU), 41, 42 Inverter, 50 battery, 52 Battery electronic control unit (battery ECU), 70 Hybrid electronic control unit (HVECU), 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator Pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor, 94 electronically controlled brake system (ECB), 96 brake master cylinder, 97 brake actuator, 98a-98d wheel speed sensor, 99 ECB electronic control unit (ECBECU), MG1, MG2 motor.

Claims (1)

A vehicle control device that is mounted on a vehicle, estimates a slip speed based on a drive wheel speed and a vehicle body speed, which are rotation speeds of drive wheels, and limits the estimated slip speed by a lower limit card value,
The lower limit guard value is decreased when the brake is turned on during running, and then the lower limit guard value is increased after the brake is turned off and the estimated slip speed exceeds a predetermined value. A vehicle lower limit guard value changing means.

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