JP2005133549A - Driving force controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent reduction of deceleration of a vehicle beyond necessity and prevent an occupant in the vehicle from sensing a shock by limiting increase of driving torque of an engine when the vehicle turns after an accelerator is turned off during straight advance running of the vehicle. <P>SOLUTION: When it is determined that the vehicle is in an engine brake condition (S60, 70) and that predetermined conditions for control start permit are satisfied (S80), it is determined whether an accelerator pedal 33 is in an accelerator off condition after the vehicle becomes a turn condition or not (S90), and engine brake force control is performed when it is determined that the accelerator pedal is in the accelerator off condition after the vehicle becomes a turn condition (S110). Engine brake force control is not performed when it is determined that the vehicle becomes a turn condition after the accelerator off condition, and driving torque of the engine 10 is not increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a driving force control device for a vehicle, and more particularly to a driving force control device that controls driving force when a vehicle turns.

  As one of driving force control devices for vehicles such as automobiles, the driving torque of the engine is increased when the deceleration of the vehicle due to the engine brake is excessive when the vehicle is turning, as described in Patent Document 1 below, for example. Conventionally, a driving force control device configured to reduce vehicle deceleration and improve vehicle running stability during a turn is known.

According to such a driving force control device, when the vehicle turns, the engine brake becomes excessive when the vehicle turns, the longitudinal force in the deceleration direction of the driving wheels becomes excessive, and the lateral force of the driving wheels decreases. It is possible to effectively prevent the running stability of the vehicle from decreasing.
Japanese Patent No. 2942566

  However, in the conventional driving force control apparatus as described above, the control for increasing the driving torque of the engine is such that the driving torque of the engine due to the driver's accelerator operation is less than a predetermined value and the lateral acceleration of the vehicle is small. Since it starts when the vehicle is above a predetermined value, the driver releases the accelerator pedal and decelerates the vehicle by the engine brake, and the vehicle turns in a turning state, as in the so-called J-turn of the vehicle. Even in such a case, there is a problem that the driving torque of the engine is increased and the deceleration of the vehicle is unnecessarily reduced.

  In particular, in the case of a vehicle in which the engine runs idle due to a fuel cut when the driver depresses the accelerator pedal, the driver releases the accelerator pedal and decelerates the vehicle with the engine brake. Even when the vehicle is turning, the fuel cut is canceled to increase the engine drive torque and the fuel supply to the engine is resumed. It is inevitable that the passenger feels shocked.

  The present invention provides a conventional drive configured to increase the engine drive torque when the engine drive torque by the driver's accelerator operation is less than a predetermined value and the lateral acceleration of the vehicle is greater than a predetermined value. The present invention has been made in view of the above-described problems in the force control device, and the main problem of the present invention is that when the vehicle is turned off after the vehicle is traveling straight ahead, the engine is turned. Limiting the increase in driving torque prevents excessive increases or sudden increases in the driving force of the vehicle, thereby reducing the deceleration of the vehicle unnecessarily or causing the vehicle occupant to feel a shock. Is to prevent.

  According to the present invention, the main problem described above is that, according to the present invention, the driving force of the vehicle by the driver's accelerator operation is equal to or less than a reference value that is smaller than the driving force of the vehicle at constant speed, and the turning degree of the vehicle is the reference value. In the vehicle driving force control device that increases the driving force of the vehicle when the value is greater than or equal to the value, when the vehicle turns in the straight state after the accelerator is turned off during the straight running of the vehicle, the vehicle has turned in the turning state. Compared to when the accelerator is turned off later, the vehicle driving force control device (configuration of claim 1) is characterized in that the amount of increase in driving force is reduced, or the driving force of the vehicle by the driver's accelerator operation In a vehicle driving force control device that increases the driving force of a vehicle when the vehicle is below a reference value smaller than the driving force at the time of traveling at a constant speed and the turning degree of the vehicle is higher than the reference value, Straight ahead When the vehicle is turned after the accelerator is turned off, the rate of increase of the driving force at the start of increasing the driving force is smaller than when the vehicle is turned off after the vehicle is turned. This is achieved by a vehicle driving force control device (structure of claim 2).

  Further, according to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, when the vehicle enters a turning state after the accelerator is turned off during the straight traveling of the vehicle. The increase in the driving force is prohibited by decreasing the increase amount in the driving force to 0 (configuration of claim 3).

  According to the present invention, in order to effectively achieve the main problems described above, the vehicle according to any one of claims 1 to 3 has a driving source for generating a driving force, and the driver operates the accelerator. When the driving force of the vehicle is equal to or less than a reference value smaller than the driving force when the vehicle is traveling at a constant speed, the driving source is configured to idle (structure of claim 4).

  According to the present invention, in order to effectively achieve the main problems described above, the vehicle target for stably running the vehicle based on the turning degree of the vehicle in the configuration of the above-described claims. The driving force is calculated, and the driving force of the vehicle is increased so that the driving force of the vehicle becomes the target driving force when the driving force of the vehicle is lower than the target driving force (configuration of claim 5). .

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of the first to fifth aspects, the amount of increase in the driving force of the vehicle is such that the vehicle turns when the turning degree of the vehicle is high. It is configured to be larger than when the degree is low (configuration of claim 6).

  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of the above claims 1 to 6, the vehicle has a torque converter provided in the drive system that transmits the drive force to the wheels. And when the input rotational speed of the torque converter is lower than the output rotational speed, an increase in the driving force of the vehicle is permitted (configuration of claim 7).

  According to the configuration of claim 1, when the vehicle is turned after the accelerator is turned off while the vehicle is traveling straight ahead, compared to when the vehicle is turned off after the vehicle is turned, Since the amount of increase in driving force is reduced, the vehicle driving force is prevented from excessively increasing when the vehicle turns while the accelerator is turned off while the vehicle is traveling straight ahead. It is possible to effectively prevent the deceleration from being lowered unnecessarily.

  Further, according to the configuration of claim 2 above, when the vehicle is turned after the accelerator is turned off while the vehicle is traveling straight ahead, compared to when the vehicle is turned off after the vehicle is turned. Since the rate of increase of the driving force at the start of the increase in driving force is reduced, the driving force of the vehicle rapidly increases when the vehicle turns while the accelerator is turned off while the vehicle is traveling straight ahead. This can effectively prevent a vehicle occupant from feeling a shock.

  According to the third aspect of the present invention, since the increase in driving force is prohibited when the vehicle turns while the accelerator is turned off while the vehicle is traveling straight ahead, the driving force of the vehicle increases excessively. This can be reliably prevented, thereby reliably and effectively preventing the deceleration of the vehicle from being unnecessarily reduced.

  According to the fourth aspect of the present invention, when the driving force of the vehicle by the driver's accelerator operation is equal to or less than the reference value that is smaller than the driving force at the time of constant speed driving of the vehicle, the driving source is idled. When the vehicle is turned after the accelerator is turned off while the vehicle is traveling straight ahead, the amount or rate of increase of the driving force is reduced compared to when the vehicle is turned off after the vehicle is turned. Therefore, when the operation of the drive source is resumed due to an increase in the driving force, the driving force of the vehicle is prevented from abruptly increasing, thereby effectively preventing the vehicle occupant from feeling a shock. can do.

  According to the fifth aspect of the present invention, the target driving force of the vehicle for stably running the vehicle is calculated based on the turning degree of the vehicle, and when the driving force of the vehicle is lower than the target driving force, Since the driving force of the vehicle is increased so that the driving force becomes the target driving force, it is reliably prevented that the driving force of the vehicle is unnecessarily increased when the driving force of the vehicle is higher than the target driving force. In addition, the vehicle driving force is increased so as to become the target driving force, so that the vehicle can be reliably and reliably turned.

  According to the sixth aspect of the present invention, the amount of increase in the driving force of the vehicle is larger when the turning degree of the vehicle is high than when the turning degree of the vehicle is low. The lower the force margin is, the larger the amount of increase in the driving force of the vehicle can be, and this can reliably and effectively reduce the running stability of the vehicle due to the excessive longitudinal force in the deceleration direction of the drive wheels. The vehicle deceleration can be ensured as much as possible.

  According to the seventh aspect of the present invention, when the input rotational speed of the torque converter is lower than the output rotational speed, an increase in the driving force of the vehicle is permitted, so that the longitudinal force of the driving wheels is in the overspeed direction. Therefore, it is possible to reliably prevent the driving force of the vehicle from being increased unnecessarily, and to reliably increase the driving force of the vehicle in a situation where the longitudinal force in the deceleration direction of the drive wheels is excessive. .

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of claim 1 or 2, the turning degree of the vehicle is determined by the magnitude of the lateral force of the driving wheel relative to the magnitude of the force that the driving wheel can generate on the road surface. It is comprised so that it may be a value which shows the ratio of (The preferable aspect 1).

  According to another preferred aspect of the present invention, in the structure of claim 1 or 2, the turning degree of the vehicle is calculated based on at least the lateral acceleration of the vehicle (Preferred aspect 2). .

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 2, the turning degree of the vehicle is calculated as a value obtained by dividing the magnitude of the lateral acceleration of the vehicle by the friction coefficient of the road surface. (Preferred embodiment 3).

  According to another preferred aspect of the present invention, in the configuration of the first to seventh aspects, the turning state of the vehicle is determined based on at least the magnitude of the lateral acceleration of the vehicle (preferably. Aspect 4).

  According to another preferred aspect of the present invention, in the configuration of claim 1 or 2 described above, when the vehicle is turned in the turning state after the accelerator is turned off during the straight traveling of the vehicle, the vehicle is in the turning state. Compared to when the accelerator is turned off after the engine is turned off, the increase amount of the drive force is reduced and the increase rate of the drive force at the start of the increase of the drive force is reduced (preferred aspect 5).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 5 described above, the decrease amount of the increase rate of the driving force at the start of the increase of the driving force does not reduce the increase amount of the driving force. It is configured to be smaller than when the increase rate of the drive force at the start of the increase of the drive force is reduced (Preferred Mode 6).

  According to another preferred embodiment of the present invention, in the configuration of claim 4, the drive source is an engine that generates a driving force using the supplied fuel, and the fuel for at least one cylinder is supplied. The engine is idled by a fuel cut to stop supply (preferred aspect 7).

  According to another preferred aspect of the present invention, in the configuration of claim 5, the target driving force of the driving wheel is calculated based on the turning degree of the vehicle, and the target of the vehicle is calculated based on the target driving force of the driving wheel. It is comprised so that a driving force may be calculated (preferred aspect 8).

  According to another preferred aspect of the present invention, in the configuration of claim 5, the target driving force of the driving wheel is calculated based on the turning degree of the vehicle, and the driving source of the driving source is calculated based on the target driving force of the driving wheel. It is comprised so that a target drive torque may be calculated (preferred aspect 9).

  According to another preferred aspect of the present invention, in the configuration of claim 7, when the input rotational speed of the torque converter is lower than the output rotational speed, the start of an increase in the driving force of the vehicle is permitted. When the input rotational speed of the torque converter is lower than the sum of the output rotational speed and a predetermined value, the vehicle is configured to allow continued increase in the driving force of the vehicle (preferred aspect 10).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram (A) and a control system block diagram (B) showing a first embodiment of a vehicle driving force control apparatus according to the present invention applied to a rear wheel drive vehicle.

  In FIG. 1, reference numeral 10 denotes an engine, and the driving force of the engine 10 is transmitted to a propeller shaft 18 via an automatic transmission 16 including a torque converter 12 and a transmission 14. The driving force of the propeller shaft 18 is transmitted to the left rear wheel axle 22L and the right rear wheel axle 22R by the differential 20, whereby the left and right rear wheels 24RL and 24RR which are driving wheels are rotationally driven.

  On the other hand, the left and right front wheels 24FL and 24FR are both driven wheels and steering wheels, and are not shown in FIG. 1, but are rack-and-pinion power that is driven in response to steering of the steering wheel by the driver. The steering device is steered in a known manner via a tie rod.

  The amount of intake air to the engine 10 is controlled by a throttle valve 28 provided in the intake passage 26, and the throttle valve 28 is driven by a throttle actuator 30 including an electric motor. The opening degree of the throttle valve 28 is controlled by the engine control unit 34 via the throttle actuator 30 in accordance with the depression amount of the accelerator pedal 33 detected by the accelerator position sensor 32. In addition, an injector 36 for injecting fuel such as gasoline is provided at the supply port of each cylinder of the intake passage 26 of the engine 10, and the fuel injection amount by the injector 36 is also controlled by the engine control device 34.

  A signal indicating the depression amount (accelerator opening Ap) of the accelerator pedal 33 is input from the accelerator position sensor 32 to the engine control device 34, and a signal indicating the opening φ of the throttle valve 28 is input from the throttle position sensor 38. Signals indicating the engine speed Ne and other engine control information are input from other sensors not shown.

  The engine controller 34 normally calculates the target engine torque Tet based on the accelerator opening Ap and the like, calculates the target opening φst of the throttle valve 28 based on the target engine torque Tet and the engine speed Ne, and opens the throttle valve 28. The degree is controlled to be the target opening φst. In particular, in the illustrated embodiment 1, when the accelerator opening Ap becomes equal to or less than the fuel cut start reference value, the engine control unit 34 determines that at least some cylinders until the accelerator opening Ap becomes equal to or greater than the fuel cut end reference value. A fuel cut for stopping the fuel injection by the injector 36 is performed. This also applies to other embodiments described later.

  Further, as will be described later, a signal indicating the target engine torque Tet is input to the engine control device 34 from the driving force control device 40 as necessary. The engine control device 34 receives a signal indicating the target engine torque Tet from the driving force control device 40. When it is input, the target opening φst of the throttle valve 28 is calculated based on the target engine torque Tet, and the output torque of the engine is increased or decreased by controlling the opening of the throttle valve 28 to the target opening φst. .

  The braking forces of the left and right front wheels 24FL, 24FR and the left and right rear wheels 24RL, 24RR are controlled by controlling the braking pressures of the corresponding wheel cylinders 46FL, 46FR, 46RL, 46RR by the hydraulic circuit 44 of the braking device 42. Although not shown in the drawing, the hydraulic circuit 44 includes a reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven in response to the depression operation of the brake pedal 48 by the driver. It is controlled by the master cylinder 50.

  As shown in FIG. 1B, the driving force control device 40 includes a signal indicating the lateral acceleration Gy of the vehicle from the lateral acceleration sensor 52, a signal indicating the friction coefficient μ of the road surface from the friction coefficient sensor 54, a vehicle speed sensor. A signal indicating the vehicle speed V is input from 56, and a signal indicating the yaw rate γ of the vehicle is input from the yaw rate sensor 58. In addition, a signal indicating the accelerator opening Ap and a signal indicating the engine rotational speed Ne as the input rotational speed of the torque converter 12 are input from the engine control device 34 to the driving force control device 40. A signal indicating the gear ratio Rt and a signal indicating the turbine speed Nto as the output speed of the torque converter 12 are input.

  The engine control device 34, the driving force control device 40, and the transmission control device 60 actually include a CPU, a ROM, a RAM, an input / output port device, etc., which are connected to each other via a bidirectional common bus. It may include a microcomputer having a configuration and a drive circuit. Further, the lateral acceleration sensor 52 and the yaw rate sensor 58 detect the lateral acceleration Gy of the vehicle and the yaw rate γ of the vehicle, respectively, when the left turn of the vehicle is positive.

  Particularly in the illustrated first embodiment, the driving force control device 40 stabilizes the vehicle when the accelerator is turned off after the vehicle is turned according to the flowcharts shown in FIGS. By calculating the target engine torque Tet for turning and outputting a signal indicating the target engine torque Tet to the engine control device 34, the driving force of the vehicle is increased and the engine braking force is reduced. When the vehicle enters a turning state after the accelerator is turned off during driving, the increase in the driving force of the vehicle is prohibited, and thus the fuel cut is released to increase the driving force of the vehicle, and the driving force of the vehicle suddenly increases. It prevents a vehicle occupant from feeling shock due to rising.

  Next, the driving force control routine according to the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals. Further, at the start of the control according to the flowchart shown in FIG. 2, the stored value Gysmin of the minimum value and the stored value Gysmax of the maximum value of the lateral acceleration Gy of the vehicle are respectively reset to 0 prior to step 10. The same applies to other embodiments described later.

  First, at step 10, a signal indicating the lateral acceleration Gy of the vehicle is read, and at step 20, the accelerator pedal 33 is in the accelerator-off state based on the accelerator opening Ap detected by the accelerator position sensor 32. The process proceeds to step 30 when an affirmative determination is made, and to step 40 when a negative determination is made.

  In step 30, the stored value Gysmin of the minimum value of the lateral acceleration Gy of the vehicle is set to the smaller one of the previous Gysmin and the absolute value Gya of the current lateral acceleration Gy of the vehicle. The stored value Gysmax of the maximum value of the lateral acceleration of the vehicle is set to the larger value of the previous Gysmax and the absolute value Gya of the current vehicle lateral acceleration Gy. In step 50, the lateral acceleration of the vehicle is set. The stored value Gyamin of the minimum value is set to the stored value Gysmax of the maximum value of the lateral acceleration of the vehicle.

  In step 60, the current engine torque Ted estimated based on the accelerator pedal opening Ap and the engine speed Ne is set to a preset reference value Tedo (driving the vehicle at a constant speed against the driving resistance acting on the engine 10). Whether or not the required torque for the engine 10 based on the driver's operation of the accelerator pedal is equal to or less than a value for driving the vehicle at a constant speed. When a negative determination is made, the control by the routine shown in FIG. 2 is once terminated, and when an affirmative determination is made, the routine proceeds to step 70.

  In step 70, it is determined whether or not the engine speed Ne is less than the output speed Nto of the torque converter 12, that is, whether or not the engine is in a brake state, and if a negative determination is made. When the control by the routine shown in FIG. 2 is once finished and an affirmative determination is made, the routine proceeds to step 80.

  While the driving force is increasing, it is determined in step 70 whether or not the predetermined value α is a positive constant and the engine speed Ne is less than the sum Nto + α of the output speed Nto of the torque converter 12 and the predetermined value α. When the negative determination is made, the control by the routine shown in FIG. 2 is once ended, and when the positive determination is made, the routine proceeds to step 80. In this case, the predetermined value α is a value for continuing to increase the driving force until the engine speed Ne becomes higher than the output speed Nto of the torque converter 12 by a predetermined amount or more. This also applies to other embodiments described later.

  In step 80, it is determined whether or not the absolute condition for permitting control start shown in the following (1) to (3) is satisfied, and when a negative determination is made, it is shown in FIG. When the control by the routine is once finished and an affirmative determination is made, the routine proceeds to step 90.

(1) Vehicle speed V is higher than reference value Vo (2) Absolute value Gya of vehicle lateral acceleration Gy is larger than reference value Gyao (3) Calculated as the product of absolute value of vehicle yaw rate γ and vehicle speed V The absolute value of the estimated lateral acceleration Gyh of the vehicle is larger than the reference value Gyho

  In step 90, it is determined whether or not the stored value Gysmin of the minimum value of the lateral acceleration of the vehicle is larger than a reference value Gyso (positive constant), that is, the accelerator pedal 33 is turned off after the vehicle is turned. 2 is determined, and if a negative determination is made, the control by the routine shown in FIG. 2 is temporarily terminated without executing the engine braking force control, and an affirmative determination is made. In step 110, engine braking force control is executed in accordance with the routine shown in FIG.

  Next, engine brake force control in the illustrated embodiment 1 will be described with reference to the flowchart shown in FIG.

  First, at step 112, the turning degree Ds of the vehicle is calculated as a value obtained by dividing the absolute value Gya of the lateral acceleration Gy of the vehicle by the friction coefficient μ of the road surface. At step 114, based on the turning degree Ds of the vehicle. A target vehicle deceleration Gxbt for stably turning the vehicle is calculated from a map corresponding to the graph shown in FIG. The friction coefficient μ of the road surface corresponds to the force that the left and right rear wheels 24RL and 24RR, which are drive wheels, can generate on the road surface, and the lateral acceleration Gy of the vehicle is generated on the road surface of the left and right rear wheels. Accordingly, the turning degree Ds of the vehicle means the degree of occupation of the lateral force with respect to the force that the left and right rear wheels can generate on the road surface.

  In step 116, the left and right rear wheels 24RL and 24RR are based on the gear ratio Rt based on the gear stage of the automatic transmission 16, the gear ratio of the differential gear device 20, the rotational radii of the left and right rear wheels 24RL and 24RR, and the target vehicle deceleration Gxbt. The target engine braking force Fetw at the ground contact point is calculated, and in step 118, the ground contact points of the left and right rear wheels 24RL and 24RR are determined based on the accelerator opening Ap and the engine speed Ne from the map not shown in the figure. The actual engine braking force Feaw at is calculated.

  In step 120, it is determined whether or not the target engine brake force Fetw is smaller than the actual engine brake force Feaw, that is, whether or not the engine brake is excessive and the output torque of the engine 10 needs to be increased. When the negative determination is made, the control by the routine shown in FIG. 3 is once ended, and when the positive determination is made, the routine proceeds to step 120.

  In step 122, a command signal for prohibiting fuel cut is output to the engine control device 34. In step 126, the target engine braking force Fet, the turning radius of the left and right rear wheels 24RL, 24RR, the automatic transmission 16 and the like. The target engine torque Tet is calculated on the basis of the gear ratio Rt based on the shift speed and the gear ratio of the differential gear device 20, and a signal indicating the target engine torque Tet is output to the engine control unit 34.

  Thus, according to the illustrated embodiment 1, the absolute value Gya of the lateral acceleration Gy of the vehicle when the accelerator pedal 33 is in the accelerator-off state in steps 20 to 50 is the minimum value of the lateral acceleration Gy of the vehicle. The maximum value of the absolute value Gya of the lateral acceleration Gy of the vehicle when the accelerator pedal 33 is in the accelerator-on state is set as the stored value Gysmin of the minimum value of the lateral acceleration Gy of the vehicle.

  In step 60, it is determined that the torque required for the engine 10 based on the driver's operation of the accelerator pedal is less than a certain value. In step 70, the engine speed Ne is less than the output speed Nto of the torque converter. If it is determined in step 80 that the absolute condition for permitting the start of control is satisfied, the stored value Gysmin of the minimum value of the lateral acceleration of the vehicle is determined from the reference value Gyso in step 90. It is determined whether or not the accelerator pedal 33 is in the accelerator-off state after the vehicle is turned by determining whether or not the vehicle is larger. If an affirmative determination is made, step 110 in FIG. The engine braking force control is executed according to the indicated routine, but when a negative determination is made, the engine braking force control is executed. Control by not shown in FIG. 2 routine is temporarily terminated.

  When the conditions of Steps 60 to 80 are satisfied and the vehicle is turning at a high turning degree and in an engine brake state, that is, the driving force of the vehicle by the driver's accelerator operation is more than the driving force at the time of driving the vehicle at a constant speed. If the vehicle is less than the reference value and the turning degree of the vehicle is more than the reference value, excessive engine braking force will be applied when the lateral force of the left and right rear wheels 24RL and 24RR as drive wheels is high. Therefore, the stability of the vehicle tends to be lowered, so that the driving force of the left and right rear wheels must be increased, and the longitudinal force in the deceleration direction of the left and right rear wheels must be reduced.

  However, since the fuel cut is performed when the accelerator pedal 33 is in the accelerator-off state, if the drive torque of the engine 10 is increased to increase the drive force of the left and right rear wheels, the fuel cut is released and the fuel to the engine 10 is released. Is resumed, the driving torque of the engine 10 increases rapidly, and the vehicle occupant feels a shock.

  According to the illustrated first embodiment, when the accelerator pedal 33 is in the accelerator-off state after the vehicle is in a turning state, an affirmative determination is made in step 90, whereby the engine is determined in step 110. 10 driving torque is increased, and the longitudinal force in the deceleration direction of the left and right rear wheels 24RL and 24RR is reduced. Therefore, an excessive engine braking force acts when the lateral force of the left and right rear wheels 24RL and 24RR is high. In step 90, when the vehicle is turned after the accelerator pedal 33 is turned off, the turning stability of the vehicle in the non-driven state can be improved. Due to the negative determination, step 110 is not executed, and the drive torque of the engine 10 is not increased. Vehicle deceleration occupant abruptly lowered or vehicle can be reliably prevented from feel the shock.

  For example, FIG. 5 shows a case where the operation of the first embodiment is compared with the case of the conventional driving force control device when the accelerator pedal 33 is in an accelerator-off state when the vehicle is in a straight traveling state and then shifts to a steady turning state. It is explanatory drawing shown.

  As shown in FIG. 5, the reduction of the depression of the accelerator pedal 33 is started at the time t1, the accelerator pedal 33 is turned off at the time t2, and the vehicle turns at the time t3. At the time t4, the start condition and permission condition for increasing the driving force of the vehicle are satisfied and the target engine torque Tet starts to increase. At the time t5, the condition for canceling the fuel cut is satisfied (Yes in step 120). (Determination), it is assumed that the vehicle has shifted to a steady turning state at time t6.

  In this case, the engine torque Te and the vehicle longitudinal acceleration Gx start to decrease at the time t1, so that the deceleration of the vehicle starts to gradually increase, and the fuel cut is started at the time t2, and at the time t4. The target engine torque Tet starts to increase, but the engine torque Te becomes constant from time t2 to time t5.

  In the case of the conventional driving force control device, as shown by the broken line in FIG. 5, the fuel cut is released at the time t5 and the increase of the engine torque Te is started. Since the increase amount of the engine torque Te is constant, the longitudinal acceleration Gx of the vehicle instantaneously increases at the time t5, and the deceleration of the vehicle rapidly decreases or the vehicle occupant may feel a shock. Unavoidable.

  On the other hand, in the case of the illustrated embodiment 1, as indicated by the solid line in FIG. 5, the target engine torque Tet is kept constant since the driving force of the vehicle is not increased after time t5. As the fuel cut continues, the vehicle's longitudinal acceleration Gx increases momentarily, ensuring that the vehicle's deceleration suddenly decreases and the vehicle occupant feels a shock. Can be prevented.

  If the accelerator pedal 33 continues to be in the accelerator-off state after time t6, the longitudinal acceleration Gx of the vehicle gradually decreases, but the driver gradually depresses the accelerator pedal 33 to gradually increase the target engine torque Tet. As a result, it is possible to reduce the deceleration of the vehicle or accelerate the vehicle while avoiding that the vehicle occupant feels a shock.

  FIG. 6 is a flowchart showing a driving force control routine in the second embodiment of the vehicle driving force control apparatus according to the present invention applied to a rear wheel driving vehicle, and FIG. 7 shows an engine braking force control routine in the second embodiment. It is a flowchart to show. In FIG. 6 and FIG. 7, the same step number as that shown in FIG. 2 and FIG. 3 is assigned to the same step number as that shown in FIG. 2 and FIG. At the start of control according to the flowchart shown in FIG. 7, the flag Fc is also reset to 0 prior to step 10, and this is the same in the third embodiment which will be described later.

  Steps 10 to 90 of the driving force control routine shown in FIG. 6 of the second embodiment are executed in the same manner as in the first embodiment, and when an affirmative determination is made in step 90, the steps 100 to 90 are executed. If the flag Fc is reset to 0 and a negative determination is made, the flag Fc is set to 1 in step 105. The flag Fc relates to whether or not the turning degree of the vehicle has become high after the accelerator is turned off as will be described later, and 1 indicates that the turning degree of the vehicle has become high after the accelerator is turned off. Show.

  When step 100 or 105 is completed, engine braking force control is executed in step 110 according to the routine shown in FIG. 7, thereby controlling the driving force of the engine 10.

  Further, steps 112 to 122 of the engine braking force control routine shown in FIG. 7 of the second embodiment are executed in the same manner as in the first embodiment. When step 122 is completed, the flag Fc is set in step 124. 1 is determined, that is, whether or not the degree of turning of the vehicle has become high after the accelerator is turned off. If a negative determination is made, in step 126, the above-described embodiment is performed. As in the case of 1, the target engine torque Tet is calculated based on the target engine brake force Fet and the like, and a signal indicating the target engine torque Tet is output to the engine control unit 34. move on.

  In step 128, the target engine torque Tet is calculated, and the current engine torque Ted is estimated based on the accelerator opening Ap and the engine speed Ne. For example, the deviation between the target engine torque Tet and the current engine torque Ted is expressed by ΔTe. The target engine torque Tet is reduced and corrected to Ted + KaΔTe with a constant correction coefficient larger than 0 and smaller than 1, and a signal indicating the target engine torque Tet after the reduction correction is output to the engine control unit 34. The output torque of the engine 10 is gradually increased to the target engine torque Tet.

  Thus, according to the illustrated second embodiment, when the accelerator pedal 33 is in the accelerator-off state after the vehicle is in the turning state, an affirmative determination is made in step 90, so in step 110. Since the driving torque of the engine 10 is increased and the longitudinal force in the deceleration direction of the left and right rear wheels 24RL and 24RR is reduced, the lateral force of the left and right rear wheels 24RL and 24RR is increased as in the case of the first embodiment. Therefore, it is possible to prevent excessive engine braking force from acting, and to improve the turning stability of the vehicle in a non-driven state.

  On the other hand, when the vehicle is turned after the accelerator pedal 33 is in the accelerator-off state, a negative determination is made in step 90, so that the flag Fc is set to 1 in step 105. Since the affirmative determination is made at step 124, the target engine torque Tet is reduced and corrected at step 128, and the increase rate of the target engine torque Tet is reduced. Therefore, the lateral forces of the left and right rear wheels 24RL and 24RR are reduced. Suppressing excessive engine braking force at high conditions and improving the turning stability of the vehicle in the non-driving state as much as possible, while reducing the number of vehicles due to a sudden increase in the driving torque of the engine 10 It is possible to reliably prevent the speed from dropping sharply and the vehicle occupant feeling a shock.

  For example, FIG. 8 shows a case where the operation of the second embodiment is compared with the case of the conventional driving force control device in the case where the accelerator pedal 33 is in the accelerator-off state when the vehicle is in the straight traveling state and then shifts to the steady turning state. It is explanatory drawing similar to FIG.

  As shown by the solid line in FIG. 8, in the case of the second embodiment, the target engine torque Tet is gradually increased from the time t5 when the increase of the driving force of the vehicle is started. It is possible to reliably prevent the engine torque Tet from rapidly increasing and the accompanying increase in the driving torque of the engine 10 associated therewith.

  FIG. 9 is a flowchart showing a driving force control routine in the third embodiment of the vehicle driving force control apparatus according to the present invention applied to a rear wheel driving vehicle, and FIG. 10 shows an engine braking force control routine in the third embodiment. It is a flowchart to show. In FIG. 9 and FIG. 10, the same steps as those shown in FIG. 2, FIG. 6, FIG. 3, and FIG. Has been.

  Steps 10 to 105 of the driving force control routine shown in FIG. 9 of the third embodiment are executed in the same manner as in the second embodiment described above, and when step 100 or 105 is completed, in step 110, FIG. Engine braking force control is executed in accordance with the routine shown, whereby the driving force of the engine 10 is controlled.

  Further, steps 112 to 126 of the engine braking force control routine shown in FIG. 10 of the third embodiment are executed in the same manner as in the second embodiment described above. In step 128, the target engine torque Tet is calculated, For example, the correction coefficient larger than 0 and smaller than 1 is set to Kb, and the target engine torque Tet is corrected to be reduced by Kb times, and a signal indicating the target engine torque Tet after the reduction correction is output to the engine control unit 34. The output torque is controlled to be the target engine torque Tet after the reduction correction.

  Thus, according to the illustrated third embodiment, when the accelerator pedal 33 is in the accelerator-off state after the vehicle has turned, the right and left rear wheels 24RL and 24RR are in the same manner as in the first embodiment. It was possible to prevent excessive engine braking force from acting when the lateral force was high, improve the turning stability of the vehicle in the non-driven state, and the accelerator pedal 33 was in the accelerator off state. When the vehicle is subsequently turned, the engine torque Te is controlled to become the target engine torque Tet that has been corrected for reduction. Therefore, excessive engine braking occurs when the lateral force of the left and right rear wheels 24RL and 24RR is high. While suppressing the application of force and improving the turning stability of the vehicle in the non-driving state as much as possible, the vehicle deceleration suddenly increases due to the rapid increase in the driving torque of the engine 10. Occupant or the vehicle drops can be effectively prevented from feel the shock.

  For example, FIG. 11 shows a case where the operation of the third embodiment is compared with the case of the conventional driving force control device in the case where the accelerator pedal 33 is in the accelerator-off state when the vehicle is in the straight traveling state and then shifts to the steady turning state. It is explanatory drawing similar to FIG.5 and FIG.8 which are shown.

  As shown by the solid line in FIG. 11, in the case of the third embodiment, the starting condition and permission condition for increasing the driving force of the vehicle are satisfied, and the target is reached from the time t4 when the increasing of the driving force of the vehicle is started. Since the engine torque Tet is corrected to be reduced, compared to the case of the conventional driving force control device, a sudden decrease in the deceleration of the vehicle due to a sudden increase in the driving torque of the engine 10 and a shock felt by the vehicle occupant. The engine braking force that is excessive as compared with the case of the second embodiment can be effectively reduced while being reliably reduced, and the effect of improving the turning traveling stability of the vehicle in the non-driven state can be enhanced.

  In each of the illustrated embodiments, the turning degree Ds of the vehicle is calculated as a value obtained by dividing the absolute value Gya of the lateral acceleration Gy of the vehicle by the friction coefficient μ of the road surface. Compared to the case where the calculation is based only on the absolute value Gya of the lateral acceleration Gy, the degree of occupancy of the lateral force with respect to the force that the left and right rear wheels can generate on the road surface, in other words, the left and right rear wheels on the road surface On the other hand, the degree of margin of the longitudinal force in the deceleration direction with respect to the force that can be generated can be accurately determined, whereby the target engine torque Tet calculated based on the target source speed Gxbt of the vehicle can be accurately calculated.

  Further, according to each embodiment shown in the figure, in step 70, it is determined whether or not the engine speed Ne is less than the output speed Nto of the torque converter. Thus, it is possible to accurately determine whether or not the engine is in the brake state, and it is possible to reliably prevent the driving force of the vehicle from being unnecessarily increased.

  Further, according to each embodiment shown in the figure, before starting the increase of the driving force, it is determined in step 70 whether or not the engine speed Ne is less than the output speed Nto of the torque converter. During the increase, it is determined in step 70 whether or not the engine speed Ne is less than the sum Nto + α of the output speed Nto of the torque converter 12 and the predetermined value α. The increase of the driving force can be surely continued until it becomes higher than the output rotational speed Nto of 12 by a predetermined amount or more.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the embodiments described above, the turning degree Ds of the vehicle is calculated as a value obtained by dividing the absolute value Gya of the lateral acceleration Gy of the vehicle by the friction coefficient μ of the road surface. The absolute value Gya of the lateral acceleration Gy is, for example, the lateral force of the vehicle, such as the absolute value of the vehicle lateral acceleration calculated as the product of the tie rod axial force, the self-aligning torque of the steering wheel, the vehicle speed V and the vehicle yaw rate γ. It may be replaced with an arbitrary value corresponding to the lateral force of the wheel, and the road friction coefficient μ may be replaced with the product of the vehicle weight or the wheel ground contact load and the road friction coefficient μ. The division by the friction coefficient μ is omitted, and the turning degree Ds of the vehicle may be an absolute value Gya of the lateral acceleration Gy of the vehicle.

  In each of the above-described embodiments, it is determined in step 70 whether or not the engine speed Ne is less than the output speed Nto of the torque converter before the driving force starts to increase. While the engine speed increases, it is determined whether or not the engine speed Ne is less than the sum Nto + α of the output speed Nto of the torque converter 12 and the predetermined value α. Regardless of whether or not the engine speed Ne is less than the output speed Nto of the torque converter, it may be corrected.

  In each of the above embodiments, the vehicle is a rear-wheel drive vehicle, but the vehicle to which the present invention is applied may be a front-wheel drive vehicle or a four-wheel drive vehicle, and the accelerator opening Ap is the fuel. When the cut start reference value or less is reached, fuel cut is performed for at least some of the cylinders until the accelerator opening Ap becomes equal to or greater than the fuel cut end reference value. May be applied.

  Further, in the above-described second embodiment, the correction coefficient Ka is a constant value larger than 0 and smaller than 1, but changes so that the correction coefficient Ka gradually approaches 1 as the driving force increase time of the vehicle elapses. By doing so, the effects of both the second and third embodiments described above may be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram (A) showing a first embodiment of a vehicle driving force control device according to the present invention applied to a rear wheel drive vehicle, and a block diagram (B) of a control system. (Example 1) 4 is a flowchart illustrating a driving force behavior control routine in the first embodiment. (Example 1) FIG. 3 is a flowchart showing an engine braking force control routine in step 110 of the flowchart shown in FIG. 2. FIG. (Example 1) It is a graph which shows the relationship between the turning degree Ds of a vehicle, and the target vehicle deceleration Gxbt. (Examples 1 and 2) Explanation of the case where the accelerator pedal 33 is in an accelerator-off state when the vehicle is in a straight traveling state and then shifts to a steady turning state in comparison with the case of a conventional driving force control device. FIG. (Example 1) It is a flowchart which shows the driving force control routine in Example 2 of the driving force control apparatus of the vehicle by this invention applied to the rear-wheel drive vehicle. (Example 2) 7 is a flowchart showing an engine braking force control routine in Embodiment 2. (Example 2) It is explanatory drawing similar to FIG. 5 which shows the action | operation of Example 2 in contrast with the case of the conventional drive force control apparatus. (Example 2) It is a flowchart which shows the driving force control routine in Example 3 of the driving force control apparatus of the vehicle by this invention applied to the rear-wheel drive vehicle. Example 3 12 is a flowchart showing an engine braking force control routine in the third embodiment. Example 3 It is explanatory drawing similar to FIG.5 and FIG.8 which shows the action | operation of Example 2 in contrast with the case of the conventional drive force control apparatus. Example 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12 Torque converter 16 Automatic transmission 34 ... Engine control device 40 ... Driving force control device 42 ... Braking device 52 ... Lateral acceleration sensor 54 ... Friction coefficient sensor 56 ... Vehicle speed sensor 58 ... Yaw rate sensor 60 ... Transmission control device

Claims (7)

  A vehicle that increases the driving force of the vehicle when the driving force of the vehicle by the driver's accelerator operation is less than a reference value smaller than the driving force of the vehicle at constant speed and the turning degree of the vehicle is more than the reference value In this driving force control device, when the vehicle is turned after the accelerator is turned off while the vehicle is traveling straight ahead, the driving is performed compared to when the vehicle is turned off after the vehicle is turned. A driving force control device for a vehicle, characterized in that an increase in force is reduced.   A vehicle that increases the driving force of the vehicle when the driving force of the vehicle by the driver's accelerator operation is less than a reference value smaller than the driving force of the vehicle at constant speed and the turning degree of the vehicle is more than the reference value In this driving force control device, when the vehicle is turned after the accelerator is turned off while the vehicle is traveling straight ahead, the drive is compared to when the vehicle is turned off after the vehicle is turned. A driving force control device for a vehicle, characterized in that the rate of increase in driving force at the start of increasing force is reduced.   2. The increase in the driving force is prohibited by reducing the increase amount of the driving force to 0 when the vehicle is turned after the accelerator is turned off during the straight traveling of the vehicle. The vehicle driving force control apparatus described.   The vehicle has a driving source that generates driving force, and the driving source is idled when the driving force of the vehicle by the driver's accelerator operation is equal to or less than a reference value smaller than the driving force at the time of traveling at a constant speed of the vehicle. The driving force control apparatus for a vehicle according to any one of claims 1 to 3.   Based on the turning degree of the vehicle, the target driving force of the vehicle for stably running the vehicle is calculated, and when the driving force of the vehicle is lower than the target driving force, the driving force of the vehicle becomes the target driving force. 5. The vehicle driving force control apparatus according to claim 1, wherein the driving force of the vehicle is increased.   6. The vehicle driving force control device according to claim 1, wherein an increase amount of the driving force of the vehicle is larger when the turning degree of the vehicle is high than when the turning degree of the vehicle is low. The vehicle has a torque converter provided in a drive system for transmitting driving force to the wheels, and permits an increase in driving force of the vehicle when the input rotational speed of the torque converter is lower than the output rotational speed. The vehicle driving force control apparatus according to claim 1.

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