JP5678570B2 - Vehicle driving force control device - Google Patents

Description

  The present invention relates to a driving force control apparatus for a vehicle.

  In Patent Document 1, when the deviation between the target driving force of the vehicle according to the driver's accelerator operation and the current driving force is large, the restriction on the rate of change of the target driving force is reduced, and the deviation is small. Discloses that the limit of the change rate of the target driving force is increased.

Japanese Patent No. 4200842

However, since the change rate of the target driving force is limited according to the deviation between the target driving force and the current driving force in the above-described conventional technology, the vehicle shifts from driving to coasting due to accelerator off. However, the following problems occur.
When the deviation is large, in order to reduce the restriction on the change rate of the target driving force, the shock generated when the driving force of the vehicle crosses zero (the driving force switches from positive to negative) becomes large. On the other hand, when the deviation is small, the limit of the rate of change of the target driving force is increased, so that the vehicle cannot be decelerated early with respect to the accelerator off, giving a feeling of idling.
An object of the present invention is to provide a vehicle driving force control device that can both relieve shock and suppress idling when shifting from driving to coasting due to accelerator off.

In order to achieve the above object, in the present invention, when the deviation between the target driving force and the actual driving force changes in the decreasing direction , the target driving force is less than the predetermined threshold value regardless of the deviation. The rate of change of the target driving force is greatly limited as compared to when the value is equal to or greater than the threshold.

  In the present invention, when the target driving force is equal to or greater than the threshold value, the limit of the change rate of the target driving force is reduced, so that the vehicle can be decelerated early with respect to the driver's accelerator off, The feeling can be suppressed. On the other hand, when the target driving force falls below the threshold, the limit on the rate of change of the target driving force is increased, so the shock that occurs when shifting from driving to coasting is reduced by reducing the change in vehicle acceleration. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view showing a power train of a hybrid vehicle according to a first embodiment to which a vehicle driving force control device of the present invention is applied. It is a block diagram which shows the control system of the power train shown in FIG. It is a block diagram according to function of the integrated controller in the control system shown in FIG. FIG. 4 is a characteristic diagram of a target driving force used when a target driving force calculation unit in FIG. 3 obtains a target driving force. FIG. 2 is an area diagram showing an electric travel (EV) mode area and a hybrid travel (HEV) mode area of a hybrid vehicle. It is a characteristic diagram which shows the target charging / discharging amount characteristic with respect to the battery electrical storage state of a hybrid vehicle. It is an example of the shift map which determines the target gear stage SHIFT. It is engine torque increase progress explanatory drawing which shows the increase progress of the engine torque to the best fuel consumption line according to a vehicle speed. It is a flowchart which shows the flow of a driving force change rate restriction | limiting process. FIG. 10 is a setting map of a decrease side change rate limit value ΔFo_d according to the vehicle speed VSP. 6 is a time chart showing a driving force change rate limiting action when shifting from driving to coasting due to accelerator off in a high vehicle speed range. 6 is a time chart showing a driving force change rate limiting effect when shifting from drive travel to coast travel due to accelerator off in a middle vehicle speed range.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the driving force control apparatus of the vehicle of this invention is demonstrated in detail based on the Example shown on drawing.
[Example 1]
FIG. 1 is a schematic plan view showing a power train of a hybrid vehicle according to a first embodiment to which the vehicle driving force control apparatus of the present invention is applied.
The hybrid vehicle of the first embodiment uses a front engine / rear wheel drive vehicle (rear wheel drive vehicle) as a base vehicle, which is a hybrid vehicle, 1 is an engine, and 2 is a drive wheel (rear wheel). .
In the power train of the hybrid vehicle shown in FIG. 1, the automatic transmission 3 is arranged in tandem at the rear of the engine 1 in the vehicle front-rear direction in the same manner as a normal rear wheel drive vehicle, and the engine 1 (crankshaft 1a) is rotated. A motor / generator (electric motor) 5 is provided in combination with the shaft 4 that transmits to the input shaft 3a of the automatic transmission 3, and this motor / generator 5 is provided as a second power source.

The motor / generator 5 acts as a drive motor and a generator, and is disposed between the engine 1 and the automatic transmission 3.
The first clutch 6 can be inserted between the motor / generator 5 and the engine 1, more specifically, between the shaft 4 and the engine crankshaft 1a, and the engine 1 and the motor / generator 5 can be disconnected by the first clutch 6. To join.
Here, the first clutch 6 is capable of changing the transmission torque capacity continuously or stepwise, for example, by controlling the clutch hydraulic oil flow rate and the clutch operation oil pressure continuously or stepwise with a proportional solenoid. It consists of a wet multi-plate clutch whose capacity can be changed.

A second clutch 7 is inserted between the motor / generator 5 and the driving wheel (rear wheel) 2, and the motor / generator 5 and the driving wheel (rear wheel) 2 are detachably coupled by the second clutch 7.
Similarly to the first clutch 6, the second clutch 7 can change the transmission torque capacity continuously or stepwise. For example, the proportional hydraulic solenoid controls the clutch hydraulic fluid flow rate and the clutch hydraulic pressure continuously or stepwise. And a wet multi-plate clutch whose transmission torque capacity can be changed.

The automatic transmission 3 may be any known one, and by selectively engaging and releasing a plurality of speed change friction elements (clutch, brake, etc.), a transmission system is obtained by combining these speed change friction elements. (Shift stage) shall be determined.
Accordingly, the automatic transmission 3 shifts the rotation from the input shaft 3a at a gear ratio corresponding to the selected shift speed and outputs the same to the output shaft 3b.
This output rotation is distributed and transmitted to the left and right rear wheels 2 by the differential gear device 8 and used for traveling of the vehicle.

By the way, in FIG. 1, instead of newly providing a dedicated second clutch 7 for releasably coupling the motor / generator 5 and the drive wheel 2, an existing shift friction element is used in the automatic transmission 3. .
In this case, the second clutch 7 performs the above-described shift speed selection function (shift function) by engaging, and the automatic transmission 3 is brought into the power transmission state, and in addition, the first clutch 6 is released and engaged, A mode selection function to be described later can be achieved, and a dedicated second clutch is unnecessary, which is very advantageous in terms of cost.

In the hybrid vehicle powertrain shown in FIG. 1 described above, when the electric travel (EV) mode used at the time of low load and low vehicle speed including when starting from a stopped state is required, the first clutch 6 is released. When the second clutch 7 is engaged, the automatic transmission 3 is brought into a power transmission state.
The second clutch 7 is a shift friction element to be fastened at the current shift stage among the shift friction elements in the automatic transmission 3, and is different for each selected shift stage.
When the motor / generator 5 is driven in this state, only the output rotation from the motor / generator 5 reaches the transmission input shaft 3a, and the automatic transmission 3 changes the rotation to the input shaft 3a to the selected shift speed. The speed is changed according to the speed and output from the transmission output shaft 3b.
Then, the rotation from the transmission output shaft 3b reaches the rear wheel 2 via the differential gear device 8, and the vehicle can be electrically driven (EV traveling) only by the motor / generator 5.

When the hybrid travel (HEV travel) mode used for high speed travel or heavy load travel is required, the automatic transmission 3 remains in the corresponding gear selection state (power transmission state) by engaging the second clutch 7 The first clutch 6 is also engaged.
In this state, both the output rotation from the engine 1 and the output rotation from the motor / generator 5 reach the transmission input shaft 3a, and the automatic transmission 3 changes the rotation to the input shaft 3a to the selected shift speed. The speed is changed according to the speed and output from the transmission output shaft 3b.
The rotation from the transmission output shaft 3b then reaches the rear wheel 2 via the differential gear device 8, and the vehicle can be hybrid-driven (HEV-driven) by both the engine 1 and the motor / generator 5.

  In such HEV traveling, when the engine 1 is operated with the optimal fuel efficiency, if the energy becomes surplus, the surplus energy is converted into electric power by operating the motor / generator 5 as a generator by this surplus energy, and this generated power is converted into electric power. By accumulating power to be used for driving the motor of the motor / generator 5, the fuel consumption of the engine 1 can be improved.

The engine 1, the motor / generator 5, the first clutch 6, and the second clutch 7 that constitute the power train of the hybrid vehicle shown in FIG. 1 are controlled by a system as shown in FIG.
The control system of FIG. 2 includes an integrated controller 20 that integrally controls the operating point of the power train. The operating point of the power train includes the target engine torque tTe, the target motor / generator torque tTm, and the target transmission of the first clutch 6. It is defined by the torque capacity tTc1 and the target transmission torque capacity tTc2 of the second clutch 7.

The integrated controller 20 includes a signal from the engine rotation sensor 11 that detects the engine rotation speed Ne and a motor / generator rotation sensor 12 that detects the motor / generator rotation speed Nm in order to determine the operating point of the power train. , A signal from the input rotation sensor 13 that detects the transmission input rotation speed Ni, a signal from the output rotation sensor 14 that detects the transmission output rotation speed No, and the accelerator pedal depression indicating the required load on the vehicle A signal from the accelerator opening sensor 15 that detects the amount (accelerator opening APO) and a storage state sensor 16 that detects the storage state SOC (carryable power) of the battery 9 that stores the power for the motor / generator 5 The signal from is input.
Of the sensors described above, the engine rotation sensor 11, the motor / generator rotation sensor 12, the input rotation sensor 13, and the output rotation sensor 14 can be arranged as shown in FIG.

The integrated controller 20 is a driving mode in which the driving force of the vehicle desired by the driver can be realized from the accelerator opening APO, the battery storage state SOC, and the transmission output rotational speed No (vehicle speed VSP) among the above input information. (EV mode, HEV mode) is selected, and target engine torque tTe, target motor / generator torque tTm, target first clutch transmission torque capacity tTc1, and target second clutch transmission torque capacity tTc2 are calculated.
The target engine torque tTe is supplied to the engine controller 21, and the target motor / generator torque tTm is supplied to the motor / generator controller 22.

The engine controller 21 controls the engine 1 so that the engine torque Te becomes the target engine torque tTe, and the motor / generator controller 22 controls the battery 9 and the inverter so that the torque Tm of the motor / generator 5 becomes the target motor / generator torque tTm. The motor / generator 5 is controlled via 10.
The integrated controller 20 supplies a solenoid current corresponding to the target first clutch transmission torque capacity tTc1 and the target second clutch transmission torque capacity tTc2 to an engagement control solenoid (not shown) of the first clutch 6 and the second clutch 7, The first clutch 6 and the first clutch 6 so that the transmission torque capacity Tc1 of the first clutch 6 matches the target transmission torque capacity tTc1, and the transmission torque capacity Tc2 of the second clutch 7 matches the target second clutch transmission torque capacity tTc2. The second clutch 7 is individually controlled for fastening force.

The integrated controller 20 selects the above-mentioned operation mode (EV mode, HEV mode), the target engine torque tTe, the target motor / generator torque tTm, the target first clutch transmission torque capacity tTc1, and the target second clutch transmission torque capacity tTc2. This calculation is executed as shown in the functional block diagram of FIG.
The target driving force calculation unit (target driving force calculation means) 30 calculates the target driving force tFo of the vehicle from the accelerator opening APO and the vehicle speed VSP using the target driving force map shown in FIG.

The operation mode selection unit 40 determines a target operation mode from the accelerator opening APO and the vehicle speed VSP using the EV-HEV region map shown in FIG.
As is clear from the EV-HEV region map shown in FIG. 5, the HEV mode is selected at high load / high vehicle speed, the EV mode is selected at low load / low vehicle speed, and the accelerator opening APO and EV When the driving point determined by the combination of the vehicle speed VSP exceeds the EV → HEV switching line and enters the HEV region, the mode switching from EV mode to HEV mode with engine start is performed, and the driving point is changed to HEV during HEV driving → When the vehicle enters the EV region beyond the EV switching line, the mode is switched from the HEV mode to the EV mode with engine stop and engine disconnection. Here, it is assumed that the EV → HEV switching line and the HEV → EV switching line move in a direction in which the accelerator opening APO decreases as the battery storage state decreases.

3 calculates a target charge / discharge amount (electric power) tP from the battery state of charge SOC using the charge / discharge amount map shown in FIG.
In the operating point command unit 60, the post-restricted target in which the value of the target driving force tFo is limited by the accelerator opening APO and the driving force change rate limiting unit (driving force change rate limiting unit) 61 described later. From the driving force tFo_lim, the target operation mode, the vehicle speed VSP, and the target charge / discharge power tP, these are used as the operating point arrival targets, and the transient target engine torque tTe and the target motor / generator torque tTm from time to time, The target solenoid current Is1 corresponding to the target transmission torque capacity tTc1 of the first clutch 6, the target transmission torque capacity tTc2 of the second clutch 7, and the target shift stage SHIFT are calculated. FIG. 7 is an example of a shift map for determining the target shift stage SHIFT, and the target shift stage SHIFT is set according to the vehicle speed VSP and the accelerator opening APO.
Also, the output required to increase the engine torque from the current operating point to the best fuel consumption line shown in FIG. 8 is calculated, and this is compared with the target charge / discharge amount (electric power) tP to request the smaller output. As an output, it is added to the engine output.

In the shift control unit 70, the target second clutch transmission torque capacity tTc2 and the target shift speed SHIFT are input, and the automatic transmission 3 so that these target second clutch transmission torque capacity tTc2 and the target shift speed SHIFT are achieved. Drive the corresponding solenoid valve in the.
As a result, the automatic transmission 3 in FIG. 1 enters the power transmission state in which the target gear stage SHIFT is selected while the second clutch 7 is engaged and controlled to achieve the target second clutch transmission torque capacity tTc2.

[Engine start processing]
The operating point command unit 60 executes an engine start process for starting the engine 1 when the target operation mode is switched from the EV mode to the HEV mode with engine start. The engine start process is as follows.
When the target operation mode is switched from the EV mode to the HEV mode, first, the transmission torque capacity tTc2 of the second clutch 7 is set so as to correspond to the transmission output shaft torque immediately before the engine start request, and then the motor / The driving force of the generator 5 is increased.
At this time, the load acting on the motor / generator 5 has an upper limit corresponding to the transmission torque capacity tTc2 of the second clutch 7, and the load exceeding this does not act on the motor / generator 5, and the motor / generator 5 5 is to increase the rotational speed Nm while slipping the second clutch 7 due to the increase of the driving force.

  Next, when the slip of the second clutch 7 and the increase in the motor / generator rotation speed Nm are expected to be completed, the first transfer clutch capacity tTc1 of the first clutch 6 that has been released is increased to a predetermined value. The clutch 6 is engaged, the engine 1 is cranked to increase the engine speed Ne, and when the engine speed Ne reaches a predetermined speed, ignition control such as fuel injection and ignition is performed on the engine 1. As a result, the engine 1 starts, that is, the engine 1 completes explosion and reaches a rotation speed at which the engine 1 can operate independently, and the first clutch 6 has a front / rear rotation difference (difference between the engine rotation speed Ne and the motor / generator rotation speed Nm). When there is no more, the first clutch 6 is completely engaged and the transmission torque capacity tTc2 of the second clutch 7 is increased and returned to the original value, and the engine start process is terminated.

[Driving force change rate limiting process]
The driving force change rate limiting unit 61 calculates a post-restricted target driving force tFo_lim that limits the change rate of the target driving force tFo by executing the control program shown in FIG.
FIG. 9 is a flowchart showing the flow of the driving force change rate limiting process.
In step S1, an estimated driving force Fo ^, which is an estimated value of the driving force of the vehicle, is calculated, and the driving force deviation ΔFo is obtained by subtracting the estimated driving force Fo ^ from the target driving force tFo. It is determined whether or not the driving force deviation previous value ΔFon ₋₁ calculated in the calculation cycle is greater than or _equal to YES, the process proceeds to step S2 if YES, and the process proceeds to step S3 if NO.

Here, the estimated driving force Fo ^ is a value obtained by, for example, estimating the engine torque and the motor / generator torque, and adding the both. For the engine torque, for example, the relationship between the engine speed Ne, the intake pressure and the engine timing with respect to the ignition timing is obtained in advance through experiments or the like to create a map, and the basic torque value is calculated by searching the map. The value can be calculated by performing a first-order lag process having a torque response time constant. The motor / generator torque can be estimated from the current value of the motor / generator 5. When the second clutch 7 is slipped, the estimated driving force Fo ^ can be estimated from the target transmission torque capacity tTc2 of the second clutch 7.
Step S1 is an actual driving force estimating means for calculating the estimated driving force Fo ^.

In step S2, after the restriction that the increase amount from the previous value of the target driving force tFo (the previous value of the target driving force calculated in the previous calculation cycle) tFon _-1 is equal to or less than the predetermined increase side change rate limit value ΔFo_i. The target driving force tFo_lim is calculated and the control is terminated. Therefore, when the value obtained by subtracting the previous value tFon _-1 from the target driving force tFo is smaller than the increase side change rate limit value ΔFo_i, the post-limit target driving force tFo_lim becomes the target driving force tFo, and the previous value from the target driving force tFo When the value obtained by subtracting tFon _-1 is equal to or greater than the increase-side change rate limit value ΔFo_i, the post-limit target driving force tFo_lim is a value obtained by adding the increase-side change rate limit value ΔFo_i to the previous value tFon _-1 .
In step S3, it is determined whether or not the target driving force tFo is equal to or greater than a predetermined torque threshold Fo_th. If YES, the process proceeds to step S4, and if NO, the process proceeds to step S5. Here, the torque threshold Fo_th is set to a value equal to or greater than a torque value that overcomes the inertial force of the rotation of the drive system from the engine 1 to the left and right rear wheels 2 and the friction torque from the automatic transmission 3 to the differential gear device 8.

In step S4, the target driving force tFo is directly used as the post-limit target driving force tFo_lim, and the control is terminated.
In step S5, the decrease side change rate limit value ΔFo_d is calculated from the vehicle speed VSP with reference to the map of FIG. FIG. 10 is a setting map of the decrease-side change rate limit value ΔFo_d according to the vehicle speed VSP, and the decrease-side change rate limit value ΔFo_d decreases as the vehicle speed VSP decreases. Note that an upper limit value and a lower limit value are provided for the decrease side change rate limit value ΔFo_d. The upper limit value is set to a value smaller than the increase side change rate limit value ΔFo_i.

In step S6, the post _- restricted target driving force tFo_lim is calculated so that the amount of decrease in the target driving force tFo from the previous value tFon _-1 is equal to or less than the reduction-side change rate limit value ΔFo_d calculated in step S5, and the control ends. To do. Therefore, when the absolute value of the value obtained by subtracting the previous value tFo _n-1 from the target driving force tFo is smaller than the decrease side change rate limit value ΔFo_d, the post-limit target driving force tFo_lim becomes the target driving force tFo and the target driving force tFo If the absolute value of the value obtained by subtracting the previous value tFo _n-1 from the value is equal to or greater than the decrease-side change rate limit value ΔFo_d, the post-limit target driving force tFo_lim subtracts the decrease-side change rate limit value ΔFo_d from the previous value tFo _n-1. It becomes the value.

Next, the operation will be described.
[Drive force change rate limiting action]
FIG. 11 is a time chart showing the driving force change rate limiting action when shifting from driving to coasting due to accelerator off in the high vehicle speed range.
At time t1, the driver starts to depress the accelerator, and during the period from time t1 to t2, the target driving force tFo increases as the accelerator opening APO increases. At this time, since the driving force deviation ΔFo, which is the deviation between the target driving force tFo and the estimated driving force Fo ^, increases with respect to the previous value ΔFon ₋₁ , in the driving force change rate limiting process shown in FIG. Thus, the flow proceeds from step S1 to step S2, and the increase amount of the post-limit target driving force tFo_lim from the previous value tFon _-1 is limited to the increase side change rate limit value ΔFo_i or less.
At time t2, the driver finishes stepping on the accelerator, and at time t3, the limited target driving force tFo_lim matches the target driving force tFo. In the period from time t3 to t4, since the accelerator opening APO is constant, the target driving force tFo does not change, and the post-restricted target driving force tFo_lim also matches the target driving force tFo.

At time point t4, the driver accelerators off, and during the period from time point t4 to t5, the driving force deviation ΔFo decreases with respect to the previous value ΔFon ₋₁ , and the target driving force tFo is equal to or greater than the torque threshold Fo_th. Therefore, in the driving force change rate limiting process, the flow proceeds from step S1 to step S3 to step S4. In step S4, the target driving force tFo is not limited and the target driving force tFo is limited to the target driving force after limiting. tFo_lim.

Since the target driving force tFo is lower than the torque threshold Fo_th at the time t5, the flow proceeds from step S1 to step S3 to step S5 to step S6 in the driving force change rate limiting process in the period from time t5 to t6. In S6, the amount of decrease of the post-limit target driving force tFo_lim from the previous value tFon _-1 is limited to a decrease side change rate limit value ΔFo_d that is smaller than the increase side change rate limit value ΔFo_i. At this time, since the vehicle speed VSP is a value corresponding to the upper limit value of the decrease side change rate limit value ΔFo_d in the map shown in FIG. 10, the decrease side change rate limit value ΔFo_d becomes the upper limit value.
At the time point t6, the post-restricted target driving force tFo_lim matches the target driving force tFo, that is, the target coast torque (<0) in coasting.

  In the conventional apparatus, when the driving force deviation is small, the limit of the rate of change of the target driving force is increased (the driving force deviation is small in FIG. 11). It cannot be decelerated until it gives a feeling of free running. On the other hand, in the first embodiment, since the vehicle can be decelerated to the target coast torque at an early stage with respect to the driver's accelerator off, the occurrence of the idling feeling can be reduced.

In addition, when the driving force of the vehicle crosses zero (switches from positive to negative), there is a shock due to clogging (backlash) between the gear teeth provided on the driving force transmission path. Occur.
Here, in Example 1, since the decrease side change rate limit value ΔFo_d is the upper limit value in the high vehicle speed range, the change rate of the driving force when the driving force of the vehicle crosses zero becomes larger than that of the conventional device. The decrease side change rate limit value ΔFo_d when the target driving force tFo falls below the torque threshold Fo_th is smaller than the decrease side change rate limit value ΔFo_d when the target driving force tFo is equal to or greater than the torque threshold Fo_th, and at high speed running Therefore, the shock that occurs is small. This is because the shock that occurs when the driving force crosses zero increases as the shift stage of the automatic transmission 3 becomes lower, whereas the high shift stage is selected during high-speed traveling.

FIG. 12 is a time chart showing the driving force change rate limiting action when the vehicle travels from coasting to coasting when the accelerator is off in the middle vehicle speed range.
The period from time t1 to t5 is the same as the period from time t1 to time t5 in FIG.
Since the target driving force tFo is lower than the torque threshold Fo_th at the time t5, the flow proceeds from step S1 to step S3 to step S5 to step S6 in the driving force change rate limiting process in the period from time t5 to t6. In S6, the amount of decrease of the post-limit target driving force tFo_lim from the previous value tFon _-1 is limited to a decrease side change rate limit value ΔFo_d that is smaller than the increase side change rate limit value ΔFo_i.

Here, since the vehicle speed VSP is lower than the vehicle speed corresponding to the upper limit value of the decrease side change rate limit value ΔFo_d in the setting map of FIG. 10 at the time point t5, the decrease side change rate limit value ΔFo_d decreases as the vehicle speed VSP decreases. Get smaller.
As described above, the shock that occurs when the drive travels to the coast travel increases as the shift speed is lower, whereas the shift speed of the automatic transmission 3 decreases as the vehicle speed VSP decreases. Selected.
In the conventional apparatus, when the driving force deviation is large, the limit of the rate of change of the target driving force is reduced (the driving force deviation is large in FIG. 12), so that the shock generated when the driving force crosses zero becomes large. On the other hand, in the first embodiment, in the low vehicle speed range, the change in driving force is reduced as the vehicle speed VSP decreases. Therefore, a larger shock occurs as the vehicle speed VSP when the driving force crosses zero is lower. Can be effectively suppressed.

  As described above, in the first embodiment, the torque threshold Fo_th for switching the reduction-side change rate limit value ΔFo_d that limits the change rate of the target drive force tFo from large to small is set to the drive system from the engine 1 to the left and right rear wheels 2. This value is equal to or greater than the torque value overcoming the rotational inertia force and the friction torque from the automatic transmission 3 to the differential gear device 8. A shock that occurs when the driving force crosses zero occurs when the driving force is positive. This is due to the influence of the rotational inertia force of the drive system from the engine 1 to the left and right rear wheels 2 and the friction torque from the automatic transmission 3 to the differential gear device 8. In other words, since the shock occurs between the time when the driving force falls below the torque threshold Fo_th and becomes zero, the limit on the rate of change of the target driving force tFo is increased when the target driving force tFo falls below the torque threshold Fo_th. This can alleviate the shock. On the other hand, when the driving force is equal to or greater than the torque threshold Fo_th, no shock will occur. In that case, by not limiting the rate of change of the target driving force tFo, the vehicle can be moved early against the driver's accelerator off. It can be decelerated and the feeling of running idle can be suppressed.

Next, the effect will be described.
The vehicle driving force control apparatus according to the first embodiment has the following effects.
(1) Target driving force calculation unit 30 for calculating the target driving force tFo, actual driving force estimation means (step S1) for calculating the estimated driving force Fo ^, and the deviation between the target driving force tFo and the estimated driving force Fo ^ When the target driving force tFo is less than the predetermined torque threshold Fo_th, the rate of change of the target driving force tFo is greater than when the target driving force tFo is equal to or greater than the torque threshold Fo_th. And a driving force change rate limiting unit 61 for greatly limiting.
As a result, the vehicle can be decelerated at an early stage with respect to the driver's accelerator off, the feeling of idling can be suppressed, and the shock that occurs when shifting from driving to coasting can be alleviated.

  (2) When the target driving force tFo is less than the torque threshold Fo_th, the driving force change rate limiting unit 61 greatly limits the rate of change of the target driving force tFo as the vehicle speed VSP decreases. Can be effectively suppressed.

(Other examples)
As mentioned above, although the form for implementing the driving force control apparatus of the vehicle of this invention was demonstrated based on the Example, the specific structure of this invention is not limited to the structure as described in an Example. Design changes and the like within the scope not departing from the gist of the invention are included in the scope of the present invention.
In step S4 of FIG. 9, the post _- restricted target driving force tFo_lim in which the amount of change from the previous value tFon _-1 of the target driving force tFo is limited by the decreasing side change rate limiting value ΔFo_d larger than the increasing side change rate limiting value ΔFo_i. You may ask for it.

The automatic transmission 3 is not limited to a stepped type, and may be a continuously variable transmission.
Instead of the target motor / generator torque tTm, the target motor / generator speed tNm may be used to control the motor / generator 5 so that the motor / generator 5 speed Nm becomes the target motor / generator speed tNm. Good.
The second clutch 7 may not be a speed change friction element existing in the automatic transmission 3 but may be a dedicated one. In this case, the second clutch 7 is provided between the input shaft 3a of the automatic transmission 3 and the motor / generator shaft 4, or between the output shaft 3b of the automatic transmission 3 and the rear wheel drive system. Can do.
The method for calculating the estimated driving force Fo ^ is arbitrary. For example, the estimated driving force Fo ^ may be calculated from the vehicle speed VSP and the longitudinal acceleration of the vehicle.

30 Target driving force calculator (Target driving force calculation means)
61 Driving force change rate limiting unit (Driving force change rate limiting means)
S1 Actual driving force estimation means

Claims (2)

Target driving force calculating means for calculating the target driving force of the vehicle;
An actual driving force estimating means for estimating an actual driving force of the vehicle;
When the deviation between the target driving force and the actual driving force changes in a decreasing direction, the target driving force is less than a predetermined threshold value when the target driving force is less than a predetermined threshold value , regardless of the deviation. Driving force change rate limiting means for greatly limiting the change rate of the target driving force;
A driving force control apparatus for a vehicle, comprising: The vehicle driving force control apparatus according to claim 1,
When the target driving force is less than the threshold, the driving force change rate limiting means greatly limits the rate of change of the target driving force as the vehicle speed decreases.

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