JP2020007948A - Traction control device of vehicle - Google Patents

Abstract

To provide a traction control device capable of improving acceleration feeling by properly determining a case when a frictional coefficient of a road surface is changed from a high state to a low state.SOLUTION: A traction control device restricts an output of a power source to suppress excessive acceleration slip of a driving wheel. The traction control device includes an acceleration degree calculation portion for calculating a longitudinal acceleration at a prescribed calculation period, a reduction amount calculation portion for calculating a reduction amount Gg[n] of a present value Ga[n] from a previous value Ga[n-1] when the previous longitudinal acceleration in the calculation period is the previous value Ga[n-1], and the present longitudinal acceleration in the calculation period is the present value Ga[n], and acquiring an integration amount Sg[n] by integrating the reduction amount Gg[n] by every calculation period, and an adjustment portion for reducing the output when the integration amount Sg[n] is over a prescribed amount sx.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a traction control device for a vehicle.

  Patent Document 1 discloses that the speed of change of the road surface μ is detected for the purpose of appropriately and promptly suppressing the slip of the drive wheel due to the decrease of the road surface μ, and when the speed is smaller than a predetermined value, that is, the road surface μ is When the vehicle shifts from a high state to a low state at a predetermined speed or higher, the correction coefficient for correcting the gain multiplied by the drive wheel slip amount is increased, the required torque is reduced, and the engine torque is reduced to suppress the drive wheel slip. Is described. In Patent Document 1, the road surface μ is calculated by “μ = K1 · (XG2 + YG2) 1/2 XG is the longitudinal acceleration, YG is the lateral acceleration, and K1 is a constant”.

  Patent Literature 2 provides a road friction coefficient equivalent value estimating means for estimating a road friction coefficient equivalent value in order to achieve both hunting prevention on a low μ road and vibration prevention on a high μ road during motor traction control, At the time of motor traction control, the road surface friction coefficient equivalent value decreases the phase delay of the motor torque command value with respect to the calculated motor torque limit value on the low friction coefficient side, and the road surface friction coefficient equivalent value is calculated on the high friction coefficient side. It is described that the phase delay of the motor torque command value with respect to the motor torque limit value is increased.

  Further, Japanese Patent Application Laid-Open No. H11-157,086 discloses a method for detecting a change in the road surface friction coefficient "when the motor angular acceleration is detected and the detected value indicates a negative angular acceleration equal to or less than the first set value, the road friction is changed from a low μ road to a high μ road. Judgment is a μ jump in which the coefficient changes suddenly. If the detected value indicates a positive angular acceleration equal to or greater than the second set value, it is judged that the μ jump is a sudden change in the road surface friction coefficient from a high μ road to a low μ road. ” Have been.

  By the way, when the vehicle accelerates (especially at the time of starting), if the friction coefficient of the road surface changes from a high state to a low state, the longitudinal acceleration of the vehicle is not sufficiently obtained, and the driver feels "sloppy". There is. The coefficient of friction of the road surface is microscopically non-uniform, even though it seems constant. For this reason, in a method of sequentially performing determination based on state quantities such as front-rear, lateral acceleration, or motor angular acceleration as in the related art, control of traction control is performed due to fluctuation of these state quantities. The adjustment of the amount may be repeated in a complicated manner. Therefore, it is desired that the road friction coefficient is appropriately determined to have changed from a high state to a low state, and stable and robust traction control can be performed.

JP-A-2001-140671 JP 2006-136175 A

  An object of the present invention is to provide a traction control device for a vehicle, in which a case where a friction coefficient of a road surface is changed from a high state to a low state is suitably determined, stable traction control is performed, and a feeling of acceleration can be improved. It is to provide.

  The vehicle traction control device (TS) according to the present invention suppresses excessive acceleration slip (Sw) of the drive wheels (WHf, WHr) to which the output (Qa) of the vehicle power source (EN) is transmitted. The output (Qa) is limited. The traction control device (TS) for the vehicle includes an “acceleration calculation unit (GA) that calculates the longitudinal acceleration (Ga) of the vehicle at a predetermined calculation cycle” and “an acceleration calculation unit (GA) that calculates the preceding longitudinal acceleration (Ga) at the calculation cycle. A previous value (Ga [n-1]), the longitudinal acceleration (Ga) of the present time in the calculation cycle is a current value (Ga [n]), and the current value of the previous acceleration (Ga [n-1]) A reduction amount (Gg [n]) of the value (Ga [n]) is calculated, and the reduction amount (Gg [n]) is integrated for each calculation cycle to obtain an integration amount (Sg [n]). Calculation unit (SG) "and" adjustment unit (CQ) that reduces the output (Qt, Qa) when the integrated amount (Sg [n]) exceeds a predetermined amount (sx) ". It consists of.

  According to the above configuration, based on the integrated amount Sg, a case where the road surface friction coefficient changes from a high state to a low state is appropriately determined, and the actual output Qa decreases to a value suitable for the road surface friction coefficient. Is done. Excessive acceleration slip Sw of the drive wheels WHf, WHr is quickly suppressed, and the convergence of the drive wheels WHf, WHr is improved. As a result, the "feeling of the driver" is eliminated, and the feeling of vehicle acceleration is improved.

1 is an overall configuration diagram of a vehicle equipped with a vehicle traction control device TS according to the present invention. It is a functional block diagram for explaining an outline of traction control device TS. FIG. 3 is a functional block diagram for explaining drive torque control of the traction control device TS. FIG. 8 is a time-series diagram for explaining processing in a decrease amount calculation block SG. FIG. 7 is a time-series diagram for explaining a process of reducing an integrated amount Sg. It is a time series diagram for demonstrating an effect | action and an effect.

<Symbols of components, etc., and subscripts at the end of the symbols>
In the following description, components, operation processing, signals, characteristics, and values having the same reference numerals, such as “ECU”, have the same function. The suffixes “f” and “r” attached to the end of the symbol related to each wheel are generic symbols indicating “f” for the front wheel and “r” for the rear wheel. For example, in a wheel speed sensor, it is described as a front wheel speed sensor VWf and a rear wheel speed sensor VWr. Further, the suffixes “f” and “r” at the end of the symbol may be omitted. When the suffixes “f” and “r” are omitted, each symbol represents its generic name. For example, "VW" represents each wheel speed sensor.

<Overall configuration of vehicle provided with traction control device TS according to the present invention>
A vehicle equipped with the vehicle traction control device TS according to the present invention will be described with reference to the overall configuration diagram of FIG. In the vehicle, the drive device YD is connected to the front wheels WHf via the drive shaft DS. In other words, the vehicle is a front-wheel drive vehicle in which the front wheels WHf are used as drive wheels.

  The vehicle includes a braking operation member BP, a braking operation amount sensor BA, an acceleration operation member AP, an acceleration operation amount sensor AA, a shift operation member HP, a shift position sensor HA, a steering operation member SW, a steering angle sensor SA, and a wheel speed sensor VW. , A yaw rate sensor YR, a longitudinal acceleration sensor GX, a lateral acceleration sensor GY, a braking device YB, and a driving device YD.

  The braking operation member (for example, a brake pedal) BP is a member that the driver operates to decelerate the vehicle. By operating the braking operation member BP, the braking torque Bq for the wheel WH is adjusted, and a braking force is generated on the wheel WH.

  A brake operation amount sensor BA is provided to detect an operation amount Ba of the brake operation member (brake pedal) BP by the driver. Specifically, as the braking operation amount sensor BA, a master cylinder hydraulic pressure sensor PM for detecting a hydraulic pressure (master cylinder hydraulic pressure) Pm in the master cylinder CM, and an operation displacement sensor for detecting an operation displacement Sp of the braking operation member BP. At least one of SP (not shown) and an operating force sensor FP (not shown) for detecting the operating force Fp of the brake operating member BP is employed.

  The acceleration operation member (for example, accelerator pedal) AP is a member that the driver operates to accelerate the vehicle and run at a constant speed. By operating the acceleration operation member AP, the driving torque Tq for the wheel WH is adjusted, and a driving force is generated on the wheel WH. An acceleration operation amount sensor AA is provided to detect an operation amount Aa of the acceleration operation member (accelerator pedal) AP by the driver. For example, an acceleration operation displacement sensor that detects an operation displacement of the acceleration operation member AP is employed as the acceleration operation amount sensor AA.

  The vehicle is provided with a shift operation member (for example, a shift lever) HP for performing a shift operation. Further, a shift position sensor HA for detecting a shift position Ha of the speed change operation member HP is provided.

  A steering operation member (for example, a steering wheel) SW is a member operated by a driver to turn the vehicle. By operating the steering operation member SW, a steering angle Sa is given to a steered wheel (for example, the front wheel WHf), a lateral force is generated on the wheel WH, and the vehicle turns. A steering angle sensor SA is provided to detect a rotation angle (steering angle) Sa of the steering operation member SW.

  The wheel WH is provided with a wheel speed sensor VW that detects a wheel speed Vw that is a rotation speed of the wheel WH. The vehicle body includes a yaw rate sensor YR that detects the yaw rate Yr of the vehicle, a longitudinal acceleration sensor GX that detects an acceleration (longitudinal acceleration) Gx in the longitudinal direction of the vehicle, and an acceleration (lateral acceleration) Gy in the lateral direction of the vehicle. A lateral acceleration sensor GY for detecting is provided.

  A braking force is generated on the wheel WH by the braking device YB. The braking device YB includes a master cylinder CM, a brake caliper CP, a wheel cylinder CW, a rotating member KT, a friction material MS, a fluid unit HU, and a braking controller ECB. The master cylinder CM, the fluid unit HU, and the wheel cylinder CW are connected via a braking fluid path HW.

  During normal braking, the fluid unit HU is not operated, and the brake fluid BF is pumped from the master cylinder CM to the wheel cylinder CW in accordance with the operation of the braking operation member BP. Each wheel WH of the vehicle is provided with a brake caliper CP, a wheel cylinder CW, a rotating member KT, and a friction material MS. Specifically, a rotating member (brake disc) KT is fixed to the wheel WH, and a brake caliper CP is arranged. The brake caliper CP is provided with a wheel cylinder CW. By adjusting the hydraulic pressure (braking hydraulic pressure) Pw in the wheel cylinder CW, a braking torque Bq (as a result, a braking force) is generated on the wheel WH.

  The fluid unit HU is operated when anti-skid control, traction control, vehicle stabilization control, or the like is performed. By the operation of the fluid unit HU, the brake hydraulic pressure Pw is adjusted independently of the operation of the brake operation member BP and individually for each wheel. Thereby, the longitudinal force (braking / driving force) of each wheel WH is controlled independently and individually. The fluid unit HU includes an electric pump, a plurality of solenoid valves, and a low-pressure reservoir.

  The fluid unit HU (in particular, the electric motor of the electric pump and the solenoid valve) is controlled by the braking controller ECB. The braking operation amount Ba (Pm, Sp, Fp), the wheel speed Vw, the yaw rate Yr, the steering angle Sa, the longitudinal acceleration Gx, the lateral acceleration Gy, and the like are input to the controller ECB. In the controller ECB, for example, anti-skid control is executed so as to suppress excessive deceleration slip of the wheel WH (for example, wheel lock). Further, traction control is performed so as to suppress excessive acceleration slip (for example, wheel spin) of the wheel WH.

  The driving device YD generates a driving force on the driving wheels (wheels connected to the driving device YD) among the wheels WH. The drive device YD includes a power source EN (also referred to as a “drive source”), a transmission TM, and a drive controller ECD. The power source EN (for example, an internal combustion engine) is controlled by the drive controller ECD according to the acceleration operation amount Aa. The transmission TM (for example, an automatic transmission) is controlled by the drive controller ECD according to the shift position Ha. A torque converter TC is included between power source EN and transmission TM, and output Qa of power source EN is transmitted to transmission TM via torque converter TC.

  The power source EN is provided with a throttle sensor TH for detecting a throttle opening Th, an injection amount sensor FI for detecting a fuel injection amount Fi, and a rotation speed sensor NE for detecting a driving rotation speed Ne. The drive controller ECD calculates the acceleration operation amount Aa (actual value), the throttle opening Th (actual value), the fuel injection amount Fi (actual value), and the driving speed Ne (actual value) of the power source EN. Output Qa of power source EN is controlled. An electric motor for driving may be used as the power source EN. In this case, the amount of current (for example, current value) Im to the power source EN and the rotation speed Nm are detected. Then, the output Qa of the driving motor is controlled based on the acceleration operation amount Aa (actual value), the energization amount Im (actual value), and the motor speed Nm (actual value).

  The transmission TM is provided with a gear position sensor GP for detecting a gear ratio (gear position) Gp (actual value). The gear ratio Gp of the automatic transmission TM is controlled by the drive controller ECD based on signals (Aa, Th, Fi, Ne, Im, Nm, etc.) related to the power source EN.

  The drive controller ECD calculates and outputs the required throttle opening Ths, the fuel injection amount Fis, and the required gear ratio Gps based on the acceleration operation amount Aa. The required throttle opening Ths, the fuel injection amount Fis, and the required gear ratio Gps are target values of the throttle opening Th, the fuel injection amount Fi, and the gear ratio Gp. The actual throttle opening Th, the actual fuel injection amount Fi, and the actual gear ratio Gp are controlled so as to match the required throttle opening Ths, the required fuel injection amount Fis, and the required gear ratio Gps. When the power source EN is an electric motor, the required energization amount (target value) Ims is calculated based on the acceleration operation amount Aa, and control is performed so that the actual energization amount Im matches the target value Ims. You.

  The drive controller ECD and the brake controller ECB share information (computed values, sensor values, etc.) via the communication bus BS. For example, traction control, vehicle stabilization control, and the like are executed by the braking controller ECB. In response to an instruction signal (target output Qt) from the brake controller ECB, the output of the power source EN is reduced by the drive controller ECD. A controller that shares information through the communication bus BS is called an “ECU (electronic control unit)”. That is, the controller ECU includes at least the drive controller ECD and the brake controller ECB.

<Overview of Traction Control Device TS>
The outline of the traction control device TS will be described with reference to the functional block diagram of FIG. The traction control device TS includes “processing for controlling the power source (drive source) EN to control the drive torque Tq of the drive wheel WHf (front wheel)” and “processing for controlling the fluid unit HU to drive the drive wheel WHf. Of controlling the braking torque Bq. The traction control device TS includes a vehicle speed calculation block VX, a drive reference speed calculation block VK, a drive torque control block QT, a braking reference speed calculation block VS, and a braking torque control block BT.

  In the vehicle speed calculation block VX, the vehicle speed Vx is calculated based on the wheel speed Vw. For example, the vehicle speed Vx is calculated based on the wheel speed Vwr of the driven wheel WHr. The driven wheel WHr is a wheel to which power from the driving device YD is not transmitted, and corresponds to a rear wheel WHr in a front-wheel-drive vehicle.

  The drive reference speed calculation block VK calculates the drive reference speed Vk based on the vehicle speed Vx. The drive reference speed Vk is a wheel speed serving as a reference when the output Qa of the power source EN is controlled (during drive torque control). For example, the reference speed Vk is determined by adding the predetermined speed vk to the vehicle speed Vx (that is, “Vk = Vx + vk”). Here, the predetermined speed vk is a predetermined value (constant) set in advance.

  In the drive torque control block QT, a target output Qt is calculated based on the drive reference speed Vk and the drive wheel speed Vwf. The target output Qt is a target value (limit value) for limiting the actual output Qa of the power source EN. Therefore, when the actual output Qa is equal to or less than the target output Qt, the output Qa of the power source EN is not limited. On the other hand, when the actual output Qa is larger than the target output Qt, the throttle opening Th and the fuel injection amount Fi (or the motor current amount Im) are reduced so that the output Qa becomes equal to or less than the target output Qt. Output Qa is reduced. As a result, the drive torque Tq of WHf is reduced, and excessive acceleration slip Sw is suppressed. Details of the drive torque control block QT will be described later.

  In a reference braking speed calculation block VS, a reference braking speed Vs is calculated based on the vehicle speed Vx. The braking reference speed Vs is a wheel speed serving as a reference when the braking hydraulic pressure Pw is controlled (during braking torque control). For example, the predetermined speed vs is added to the vehicle speed Vx to determine the reference speed Vs (that is, "Vs = Vx + vs"). Here, the predetermined speed vs is a predetermined value (constant) set in advance, and has a relationship of “vs> vk”.

  In the braking torque control block BT, the fluid unit HU is controlled based on the braking reference speed Vs and the driving wheel speed Vwf. Specifically, the brake fluid pressure Pw is adjusted such that the drive wheel speed Vwf approaches and matches the brake reference speed Vs. Note that the predetermined speed vs is set to a value higher than the predetermined speed vk, so that the braking reference speed Vs is higher than the driving reference speed Vk. Therefore, in the traction control, first, the driving torque control is executed. When the drive wheel speed Vwf does not increase or does not sufficiently decrease despite the output Qa being reduced by the drive torque control, the acceleration slip Sw of the drive wheel WHf is quickly reduced by the braking torque control block BT. Thus, the braking hydraulic pressure Pwf is increased (that is, the braking torque Bq of the drive wheel WHf is increased).

<Drive torque control of traction control device TS>
The details of the drive torque control of the traction control device TS will be described with reference to the functional block diagram of FIG. By the driving torque control, the output (power) Qa of the power source EN is limited so as to suppress the excessive acceleration slip Sw of the driving wheel WHf (the wheel to which the output Qa is transmitted), and the driving torque Tq is reduced. The drive torque control includes a vehicle speed calculation block VX, a drive reference speed calculation block VK, a drive wheel average speed calculation block VH, a proportional / integral control block QS, a longitudinal acceleration calculation block GA, a decrease amount calculation block SG, and an adjustment processing block. It is composed of CQ.

  In the vehicle speed calculation block VX, the vehicle speed Vx is calculated based on the wheel speed Vw (particularly, the wheel speed Vwr of the driven wheel WHr). In the drive reference speed calculation block VK, a predetermined speed vk (for example, a constant) is added to the vehicle body speed Vx to determine a drive reference speed Vk (also simply referred to as “reference speed Vk”).

  In a driving wheel average speed calculation block VH, a driving wheel average speed Vh (also simply referred to as “average speed Vh”) is calculated based on the wheel speed Vwf of the driving wheel WHf. The drive wheel WHf is a wheel to which power from the drive device YD is transmitted, and corresponds to the front wheel WHf in a front-wheel drive vehicle. The average speed Vh is an average value of the two drive wheel speeds Vwf. The acceleration slip Sw is calculated based on the reference speed Vk and the average speed Vh. Specifically, the acceleration slip Sw is determined by subtracting the reference speed Vk from the average speed Vh (that is, “Sw = Vh−Vk”).

  In the proportional / integral control block QS, the proportional / integral control is executed based on the acceleration slip Sw. Specifically, when the acceleration slip Sw becomes equal to or more than the predetermined value sz, the execution of the traction control is started. Then, the acceleration slip Sw is multiplied by the proportional gain Kp (that is, “Kp × Sw”). Further, the time integral of the acceleration slip Sw is multiplied by the integral gain Ki (that is, “KiｉSw”). Further, these are added to calculate the required output Qs (that is, “Qs = Kp × Sw + Ki × ∫Sw”). The required output Qs is a target value (limit value) for limiting the actual output Qa. The execution of the traction control may be started when the required output Qs becomes equal to or more than the predetermined value qs. The predetermined values sz and qs are preset constants.

  In the acceleration calculation block GA (corresponding to an “acceleration calculation unit”), the longitudinal acceleration Ga is calculated based on the vehicle speed Vx. The longitudinal acceleration Ga is the actual longitudinal acceleration (actual acceleration) of the vehicle (vehicle body). Specifically, the vehicle speed Vx is time-differentiated at a predetermined calculation cycle (for example, every several milliseconds), and the longitudinal acceleration Ga is calculated. Further, the longitudinal acceleration Gx detected by the longitudinal acceleration sensor GX may be employed as the longitudinal acceleration Ga. Further, both the longitudinal acceleration Gx (detected value) and the longitudinal acceleration Ga (calculated value) may be used as the longitudinal acceleration Ga so as to improve the robustness.

  In the decrease amount calculation block SG (corresponding to the “reduction amount calculation unit”), the integrated amount Sg is calculated based on the longitudinal acceleration Ga. The integrated amount Sg is a decrease amount from the peak value of the longitudinal acceleration Ga. Specifically, in the decrease amount calculation block SG, in the calculation cycle of the controller ECU, the current longitudinal acceleration Ga [n] (corresponding to the “previous value”) from the previous longitudinal acceleration Ga [n−1] (corresponding to “previous value”) The amount of reduction Gg [n] corresponding to “current value” is calculated. Here, "n" at the end of the symbol indicates the operation cycle, where "n" indicates the current (current) operation cycle and "n-1" indicates the immediately previous operation cycle (previous), respectively. Represent.

  In the reduction amount calculation block SG, the reduction amount Gg [n] is sequentially accumulated for each calculation cycle. The reduced amount 減少 Gg [n] integrated up to the current calculation cycle “n” is referred to as “integrated amount Sg [n]” (that is, “Sg [n] = ΣGg [n]”). That is, the current reduction amount Gg [n] is added to the integration amount Sg [n-1] up to the previous calculation cycle “n−1”, and the current integration amount Sg [n] is determined.

  Further, in the decrease amount calculation block SG, when the current longitudinal acceleration (current value) Ga [n] increases from the previous longitudinal acceleration (previous value) Ga [n-1], the current integrated amount Sg [ n] is reduced to a predetermined ratio rs of the previous integrated amount Sg [n−1] (that is, “Sg [n] = rs × Sg [n−1]”). Here, the predetermined ratio rs is a preset constant. For example, the predetermined ratio rs is set to “0%”. In this case, when the longitudinal acceleration Ga increases, the integrated value Sg is reset to “0”.

  In addition, the decrease amount calculation block SG includes a timer (time counter). This timer calculates the continuation of time. For the first time after the traction control is started, the continuation time is counted from the time when the longitudinal acceleration Ga decreases (the corresponding calculation cycle). The integrated value Sg is reset to “0” when a predetermined time tx has elapsed from the time when the state where the integrated value Sg is larger than the predetermined amount sx is satisfied for the first time. Here, the predetermined amount sx and the predetermined time tx are constants set in advance.

  In an adjustment processing block CQ (corresponding to an “adjustment unit”), the required output Qs (also referred to as “required torque”) is adjusted based on the integrated amount Sg, and the target output Qt (also referred to as “target torque”) is calculated. Is done. The target output Qt (target torque) is a final target value of the limited torque in the drive torque control. In the case of “Qa ≦ Qt”, no limitation is performed and the actual output Qa is not reduced. In the case of "Qa> Qt", the power source EN is controlled so that the actual output Qa decreases to the target output Qt (reduction of the throttle opening Th, the fuel injection amount Fi, and the motor energization amount Im).

  Specifically, in the adjustment processing block CQ, when the integrated amount Sg [n] exceeds a predetermined amount sx, the required output Qs is reduced by the adjustment output Qg (also referred to as “adjustment torque”), and the target output Qt is determined (ie, "Qt = Qs-Qg"). The adjustment output Qg is for reducing and adjusting the required output Qs to determine the final target output Qt. The predetermined amount sx is a threshold value for determining whether or not the required output Qs is adjusted to be reduced or not (that is, whether or not to calculate the adjusted output Qg), and is a predetermined predetermined constant. It is.

  For example, the adjustment output Qg is set as a predetermined torque qg. The predetermined torque qg is a preset constant. Further, the adjustment output Qg can be determined based on at least one of the slip state sw and the duration time tg. The slip state sw is a value of the acceleration slip Sw at the time when “Sg> sx” is satisfied (a corresponding calculation cycle). As shown in the calculation map Zs of the blowing section, the calculation is performed such that the adjustment output Qg increases as the slip state sw increases. The fact that the slip state sw is large is based on the fact that the target output Qt should be made smaller.

  The continuation time tg is a time from the time when the increase of the integrated amount Sg is started to the time when “Sg> sx” is satisfied. As shown in the calculation map Zt, the adjustment output Qg is calculated so as to be smaller as the duration tg is longer. The long duration tg is based on the fact that the longitudinal acceleration does not decrease so much and the acceleration slip Sw does not increase rapidly.

  In the traction control device TS, the actual longitudinal acceleration Ga is calculated. Then, the amount of decrease Gg of the longitudinal acceleration Ga (the amount of decrease Gg [n] in the present value Ga [n] from the previous value Ga [n-1]) is calculated in each calculation cycle. This reduction amount Gg is sequentially integrated, and determined as an integration amount Sg (= ΣGg). In other words, the total of the reduction amounts Gg from the time when the longitudinal acceleration Ga exhibits the peak value and the decrease in the longitudinal acceleration Ga is started (ie, the calculation cycle in which the decrease in the longitudinal acceleration Ga is determined) is the integrated amount Sg It is. In the output adjustment processing, if the integrated amount Sg is equal to or smaller than the predetermined amount sx, the required output Qs is not adjusted (that is, “Qt = Qs”). On the other hand, when the integrated amount Sg becomes larger than the predetermined amount sx, the adjustment output Qg (adjustment torque) is reduced from the request output Qs (request torque), and the target output Qt (target torque) is rapidly reduced. (I.e., "Qt = Qs-Qg"). The predetermined amount sx is a threshold (a preset constant) for determining whether or not the adjustment output Qg is necessary.

  The adjustment for decreasing the target output Qt is ended when the increase in the longitudinal acceleration Ga is started. Alternatively, the decrease adjustment can be ended when the integrated value Sg becomes equal to or less than the predetermined amount sx. Further, the decrease adjustment may be ended when a predetermined time tx (a preset constant) has elapsed from the time when “Sg> sx” is satisfied for the first time. At the end of the decrease adjustment, the adjustment output Qg is not immediately set to “0”, but is gradually reduced (with the time change gradient limited) toward “0”. The target output Qt is smoothly increased to the required output Qs so that a sudden change in the output Qa is suppressed.

  In the traction control device TS, the target output Qt is greatly reduced when the longitudinal acceleration Ga continues to decrease during vehicle acceleration. That is, based on the integrated amount Sg determined according to the state quantity over a certain calculation cycle, instead of the state quantity determined for each calculation cycle as in the related art, the road surface has a high friction coefficient. The case where the state has changed to a low state is appropriately determined. In other words, since the road surface friction state is determined by using not only the current state quantity but also the past state quantity, the complexity of the control due to the fluctuation of the control amount of the traction control is suppressed. Then, based on the determination result, the actual output Qa is reduced to a value suitable for the road surface friction coefficient. Excessive acceleration slip Sw of the drive wheel WHf is quickly suppressed, and the convergence of the drive wheel WHf is improved. As a result, the driver's feeling of acceleration of the vehicle is improved.

<Process in the decrease amount calculation block SG>
With reference to the time-series diagram of FIG. 4, the processing in the reduction amount calculation block SG (reduction amount calculation unit) will be described. The symbols in parentheses at the end of each symbol indicate at what point (corresponding operation cycle) it is. For example, “Ga [t7]” indicates the longitudinal acceleration Ga at the time point t7.

  Until time t4, the longitudinal acceleration Ga is gradually increasing. Therefore, “Gg = 0” is calculated, and “Sg = 0”. At time t5, the longitudinal acceleration Ga [t5] decreases from the longitudinal acceleration Ga [t4]. Therefore, at time t5, "Gg [t5] = Ga [t5] -Ga [t4]" is calculated. At time t5, “Sg [t5] = 0”, so “Sg [t5] = Gg [t5]” is calculated.

  At time t6, the longitudinal acceleration Ga [t6] decreases from the longitudinal acceleration Ga [t5]. At time t5, "Gg [t6] = Ga [t6] -Ga [t5]" is calculated. At time t6, since "Sg [t5] = Gg [t5]", "Sg [t6] = Sg [t5] + Gg [t6]" is calculated.

  Similar calculations are repeated for each calculation cycle. That is, the amount of decrease Gg [n] of the current longitudinal acceleration Ga [n] from the previous longitudinal acceleration Ga [n-1] is calculated. Then, the current reduction amount Gg [n] is added to the previous integration amount Sg [n-1], and the current integration amount Sg [n] is determined. At time point t8, the integrated amount Sg [t8] is calculated as “Sg [t7] + Gg [t8]”. Until time t8, since the integrated amount Sg is equal to or less than the predetermined amount sx, the adjustment of the required output Qs is not performed, and the required output Qs is determined as it is as the target output Qt (that is, “Qg = 0, Qt = Qs ").

  At time point t9, the integrated amount Sg [t9] is calculated as “Sg [t8] + Gg [t9]”. At time t9, since the integrated amount Sg exceeds the predetermined amount sx, the regulated output Qg is reduced from the required output Qs, and the target output Qt is determined (that is, “Qt = Qs−Qg”). As a result, the target output Qt is significantly reduced (ie, sharply reduced). When the longitudinal acceleration Ga continues to decrease, the state of “Sg> sx” is maintained, so the state of “Qt = Qs−Qg” (decrease adjustment) is continued.

  At the time point t15, the longitudinal acceleration Ga [t15] increases more than the longitudinal acceleration Ga [t14]. In this case, the integrated amount Sg [t15] is reduced to a predetermined ratio rs (that is, Sg [t15] = rs × Sg [t14]). For example, when “rs = 0%” is set, the integrated amount Sg [t15] is reset to “0”. When “rs = 50%” is set, the integrated amount Sg [t15] is determined to be “１ ／” of the integrated amount Sg [t14] (see the characteristic indicated by the broken line). Thereafter, when the longitudinal acceleration Ga decreases, the integrated amount Sg increases. However, when the longitudinal acceleration Ga increases, the integrated amount Sg repeatedly decreases.

  As conditions for terminating the decrease adjustment of the target output Qt, “the longitudinal acceleration Ga increases”, “the integrated amount Sg is equal to or less than the threshold value sx”, and “the duration of the decrease adjustment is a predetermined time tz (a preset constant)” At least one of the above is adopted. At time t15, the “increase of the longitudinal acceleration Ga” or the “condition of“ Sg ≦ sx ”due to the decrease of the integrated amount Sg” is satisfied, and the decrease adjustment of the target output Qt is ended. When the output adjustment is completed, the adjusted output Qg is gradually reduced and the target output Qt is gradually increased so as to avoid a sudden change in the actual output Qa.

<Process for reducing integrated amount Sg>
The process of reducing the integrated amount Sg will be described with reference to the time series diagram of FIG. Here, the predetermined ratio rs is set to “0%”.

  FIG. 5A shows a decreasing process when the longitudinal acceleration Ga increases. Until the time point u4, the longitudinal acceleration Ga increases, so that “Sg = 0”. At time u5, “Ga [u5] <Ga [u4]”, so the integrated amount Sg [u5] is calculated. Thereafter, until the time point u9, since the longitudinal acceleration Ga decreases, the integrated amount Sg increases. However, since “Sg ≦ sx”, “Qt = Qs” is determined. At time point u10, “Ga [u10] ≧ Ga [u9]” is satisfied, and the longitudinal acceleration Ga is increased. If the current longitudinal acceleration Ga [n] is equal to or greater than the previous longitudinal acceleration Ga [n-1], the current integrated amount Sg [n] is determined by adding a predetermined ratio to the previous integrated amount Sg [n-1]. It is reduced to a value multiplied by rs (= rs × Sg [n−1]). As a result, the integrated amount Sg [u10] is reset to “0” because “rs = 0%”. At time point u12, the longitudinal acceleration Ga is reduced again. Accordingly, the integrated amount Sg is increased from “0”. Only when the longitudinal acceleration Ga continues to decrease, the target output Qt is decreased, so that control reliability can be improved.

  FIG. 5B shows a decreasing process when the increase of the integrated amount Sg exceeds the predetermined time tx. At time point v5, the calculation of the integrated amount Sg is started, and starts to increase from “0”. As the longitudinal acceleration Ga decreases, the integrated amount Sg is sequentially increased. Since the state of “Sg ≦ sx” is continued, the reduction of the target output Qt is not performed. At time point v17, the duration of “Sg ≦ sx” becomes equal to or longer than tx. At this time, the integrated amount Sg [v17] is reset to “0”. That is, when the state where the integrated amount Sg [n] is equal to or less than the predetermined amount sx continues for the predetermined time tx or more, the integrated amount Sg [n] is reset to “0”, and the target output Qt decreases. I can't. Although the integrated amount Sg has been increased, when it takes time to reach the predetermined amount sx, the road surface friction coefficient is not so low, and the necessity for the rapid decrease of the target output Qt is low. Unnecessary reduction of the target output Qt can be avoided by the reduction processing based on the duration of the integrated amount Sg, and the reliability of control can be improved.

<Action / Effect>
The operation and effect of the traction control device TS according to the present invention will be described with reference to the time series diagram of FIG. FIG. 6A shows a case where the present invention is not applied, and FIG. 6B shows a case where the present invention is applied. The acceleration operation amount Aa is made constant, and an instruction output Qd (constant value ta) is instructed to the power source EN by the drive controller ECD. It is assumed that the friction coefficient of the vehicle traveling path has changed from a high state to a low state. In the traction control, the command output Qd is limited by the target output Qt (<Qd), and the output Qa of the power source EN is suppressed (reduced). Thus, excessive acceleration slip of the wheel WH (wheel spin in an extreme case) is suppressed.

  First, conventional traction control to which the present invention is not applied will be described with reference to FIG. Until the time point x1, the traction control has not been started, so the target output Qt has not been calculated. Immediately before the time point x1, the road surface friction coefficient decreased. Therefore, at time point x1, the acceleration slip Sw (= Vh−Vk) of the drive wheel WHf increases, reaches the traction control threshold value, and the drive torque control is started. Then, the proportional / integral control based on the acceleration slip Sw is executed, and the required output Qs is calculated. In the conventional control, since the integrated amount Sg is not calculated, the target output Qt is not reduced by the required output Qs, and “Qt = Qs” is determined. The command output Qd by the driver is limited by the target output Qt by the traction control, but since the restriction is insufficient, it takes time for the average speed Vh to converge to the drive reference speed Vk. Since the acceleration slip Sw becomes excessive and a driving force corresponding to the road surface friction coefficient cannot be obtained, the driver may feel "slack" in vehicle acceleration.

  Next, the traction control device TS according to the present invention will be described. Traction control device TS suppresses excessive acceleration slip Sw of drive wheel WHf to which output Qa of power source EN is transmitted. The traction control device TS includes a longitudinal acceleration calculation block GA, a decrease amount calculation block SG, and an adjustment processing block CQ. The longitudinal acceleration calculation block GA (acceleration calculation unit) calculates the longitudinal acceleration Ga at a predetermined calculation cycle. For example, in the longitudinal acceleration calculation block GA, the longitudinal acceleration Ga is calculated by differentiating the time based on the vehicle speed Vx corresponding to the wheel speed Vw. Further, based on the longitudinal acceleration Gx (detected value) detected by the longitudinal acceleration sensor GX, the longitudinal acceleration Gx can be filtered to determine the longitudinal acceleration Ga.

  In the reduction amount calculation block SG (reduction amount calculation unit), the previous longitudinal acceleration Ga [n-1] (previous value) is stored in the calculation cycle. In the calculation cycle, the current longitudinal acceleration Ga [n] (current value) is obtained. Then, the amount of reduction Gg [n] of the current value Ga [n] from the previous value Ga [n-1] is calculated. The reduction amount Gg [n] is integrated for each calculation cycle to determine the integration amount Sg [n]. In the adjustment processing block CQ (adjustment unit), when the integrated amount Sg [n] exceeds a predetermined amount sx (a predetermined threshold for determination), the output Qa of the power source EN is reduced. Specifically, the adjustment output Qg determined according to the integrated amount Sg is subtracted from the required output Qs calculated based on the acceleration slip Sw, and the target output Qt is sharply reduced. The drive controller ECD controls the actual output Qa to approach and match the target output Qt, so that the output Qa is rapidly reduced.

  The operation of the traction control device TS will be described with reference to FIG. Similar to the conventional control, the traction control is started at the time point x1. From time point x1, the integrated amount Sg is calculated based on the decrease amount Gg of the longitudinal acceleration Ga. In “Sg ≦ sx”, the required output Qs is determined as the target output Qt. At the time x2 when the longitudinal acceleration Ga is continuously reduced and “Sg> sx” is satisfied, the adjustment output Qg is calculated, the adjustment output Qg is reduced from the required output Qs, and the target output Qt is reduced. At time point x2, target output Qt is sharply reduced from value tb to value tc. Based on the integrated amount Sg integrated over a plurality of calculation cycles, it is determined that the road surface friction coefficient has changed from a high state to a low state, and the actual output Qa is reduced to a value suitable for the road surface friction coefficient. Is reduced. As a result, the average speed Vh (the average value of the two drive wheel speeds Vwf) quickly approaches the drive reference speed Vk. That is, the convergence of the wheel speed Vwf of the driving wheel WHf is improved, and the driving force of the driving wheel WHf can be suitably secured according to the decrease in the road surface friction coefficient.

  In the decrease amount calculation block SG, when the current value Ga [n] is equal to or larger than the previous value Ga [n-1], the integrated amount Sg [n] is obtained by multiplying the integrated value Sg [n-1] by a predetermined ratio rs. It is reduced to a value (eg, reset to “0 (zero)”). Further, in the decrease amount calculation block SG, when the state in which the integrated amount Sg [n] is equal to or smaller than the predetermined amount sx is continued for a predetermined time tx or more, the integrated amount Sg [n] is set to “0 (zero)”. Is reset to Thereby, the reliability of the control in reducing the target output Qt can be improved.

<Other embodiments>
Hereinafter, other embodiments will be described. In other embodiments, the same effects as above can be obtained. In the above embodiment, the traction control device TS is applied to a front-wheel drive vehicle in which the drive wheels connected to the power source EN are the front wheels WHf. The traction control device TS can be applied to a rear-wheel drive vehicle. In this case, the driving wheel is the rear wheel WHr, and the driven wheel is the front wheel WHf. Also in the rear-wheel drive vehicle, at least one of a differential value (computed value) of the vehicle body speed Vx and a detected longitudinal acceleration Gx (detected value of the longitudinal acceleration sensor GX) is adopted as the longitudinal acceleration Ga.

  The traction control device TS may be applied to a four-wheel drive vehicle. In the four-wheel drive vehicle, it is preferable that the detected longitudinal acceleration Gx is adopted as the longitudinal acceleration Ga. When the four wheels are drive wheels, it is based on the fact that all the wheels WH include the acceleration slip Sw.

TS: traction control device, EN: power source, TM: transmission, ECU: controller, ECB: braking controller, ECD: drive controller, VW: wheel speed sensor, GX: longitudinal acceleration sensor, AA: acceleration operation amount sensor, GA ... longitudinal acceleration calculation block, SG ... decrease amount calculation block, CQ ... adjustment processing block, Vw ... wheel speed, Vx ... body speed, Vk ... reference speed (drive wheel), Ga ... longitudinal acceleration, Sw ... acceleration slip (drive wheel) ), Gg: decrease amount, Sg: integrated amount, Qg: adjustment output, Qs: required output, Qt: target output, Qa: actual output.

Claims (1)

A traction control device for a vehicle that limits the output so as to suppress excessive acceleration slip of a drive wheel to which an output of a power source of the vehicle is transmitted,
An acceleration calculation unit that calculates the longitudinal acceleration of the vehicle at a predetermined calculation cycle,
In the calculation cycle, the previous longitudinal acceleration is used as a previous value, in the calculation cycle, the current longitudinal acceleration is used as a current value, a decrease in the current value from the previous value is calculated, and the decrease is calculated in the calculation cycle. A reduction amount calculation unit that integrates each time to obtain an integration amount;
An adjusting unit that reduces the output when the integrated amount exceeds a predetermined amount;
A traction control device for a vehicle, comprising: