JP3627265B2 - Vehicle driving force control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a driving force (traction) control device for a vehicle, and more particularly to a second throttle valve that is normally open in series with a throttle valve in an intake passage of an engine and closes the second throttle valve when a drive wheel slip occurs. The present invention relates to a device that drives in a direction.
[0002]
[Prior art]
On slippery road surfaces such as wet asphalt roads and snowy roads, the driving wheel slips during acceleration, and the vehicle cannot be accelerated sufficiently, or the stability of the vehicle is lowered due to a tail swing.
Therefore, as a driving force control device for a vehicle, fuel cut control for reducing engine output, throttle opening control, and brake control for suppressing slippage of driving wheels by a braking force are known.
[0003]
Although each control can suppress slipping of the drive wheels and perform highly responsive control, a hydraulic pump as a brake pressure source and brake piping for that purpose must be provided, fuel cut control and throttle opening control There is a problem that the cost and fuel increase.
In addition, the fuel cut control can utilize the engine control software and can suppress an increase in cost and can perform a highly responsive control. However, there is a problem that the deterioration of the catalyst is accelerated due to the afterburning of the unburned gas in the catalyst.
[0004]
Further, the throttle control has a problem that the response is not good compared to the brake control and the fuel cut control.
For this reason, combining the fuel cut control and the throttle opening control, the initial slip is controlled with high response by the fuel cut control, and in series with the throttle valve that is opened and closed in conjunction with the accelerator pedal as the throttle control in the engine In addition, a second throttle valve that is driven by a DC motor (step motor) is provided, and when the occurrence of slip is detected based on the difference in rotational speed between the driving wheel and the driven wheel, the second throttle valve is closed, By reducing the driving force (engine torque), it is possible to improve vehicle stability by improving startability and acceleration and preventing tail swing.
[0005]
[Problems to be solved by the invention]
However, even in the driving force control device using the throttle opening control, the DC motor is used as the driving actuator for the second throttle valve, and the opening can be precisely controlled by using the DC motor. In particular, when the purpose of use is limited only to the improvement of acceleration at low speeds including start assistance for FF vehicles, it is not necessary to control so closely, so the use of a DC motor increases the cost. There was a problem.
[0006]
In addition, the DC motor is heavy in terms of the speed change mechanism and is generally integrated with the throttle chamber, and there is a problem that it is not versatile.
Accordingly, an attempt has been made to develop a low-cost device that does not require a DC motor as a configuration in which the second throttle valve is switched to two stages of full opening and full closing.
By the way, in the case of the simple control that switches to the two stages as described above, the opening degree of the second throttle valve in the fully closed position (hereinafter referred to as the fully closed opening degree) is such that the vehicle can run while suppressing slip on the snowy road. For example, the opening degree is set to about 1/8 when fully opened.
[0007]
However, in this simple control that closes to a certain fully closed opening during traction control, for example, when the engine speed is high when the second throttle valve is fully closed, the intake negative pressure increases. The engine torque decreases, and negative torque (a state that is insufficient for the torque required to rotate the engine at a high speed) is generated in a high speed range above a predetermined range, and so-called engine braking is induced. .
[0008]
Similarly, when the vehicle speed is high when the second throttle valve is fully closed, the traveling load due to air resistance increases, and in the high speed range above a predetermined level, the engine torque when the second throttle valve is fully closed from the traveling load. The driving force of the vehicle due to is reduced, and in this case, engine braking is also induced. In this way, when the engine brake is induced, a feeling of deceleration is generated, and in the case of an FR vehicle, there is a possibility of causing spin, and in the case of an FF vehicle, the steering feeling is deteriorated and tuck-in may occur.
[0009]
The present invention has been made in view of such a conventional problem, and in a situation where the vehicle is decelerated by the traction control, the traction control is prohibited, so that the traveling performance is favorably maintained in the simple traction control. An object of the present invention is to provide a vehicle driving force control device that can be used.
[0010]
[Means for Solving the Problems]
Therefore, the vehicle driving force control apparatus according to the invention of claim 1
A throttle valve disposed in the intake passage of the engine and controlled to be switched in two stages, a fully open position and a fully closed position of a predetermined opening;
Slip state detecting means for detecting the slip state of the drive wheels of the vehicle;
Driving force reduction control means for reducing the driving force of the vehicle by controlling the throttle valve to a fully closed position in accordance with the detected slip state;
When the throttle valve is controlled to the fully closed position, a rotation speed is set when the engine output torque is balanced with a torque necessary to maintain the engine rotation speed, and the engine rotation speed when the slip occurs is set as described above. Traveling load detecting means for detecting a high traveling load state when the rotation speed is greater than
Driving force reduction control prohibiting means for prohibiting the operation of the driving force reduction control means when the high running load state is detected by the driving load detection means;
It is characterized by including.
[0011]
According to a second aspect of the present invention, a vehicle driving force control device includes:
A throttle valve disposed in the intake passage of the engine and controlled to be switched in two stages, a fully open position and a fully closed position of a predetermined opening;
Slip state detecting means for detecting the slip state of the drive wheels of the vehicle;
Driving force reduction control means for reducing the driving force of the vehicle by controlling the throttle valve to a fully closed position in accordance with the detected slip state;
A vehicle speed at which the running resistance determined by the vehicle speed is balanced with the driving force of the vehicle generated when the throttle valve is controlled to the fully closed position is set, and the vehicle speed at the time of occurrence of slip is larger than the set vehicle speed. a running load detecting means for detecting a high running load condition,
Driving force reduction control prohibiting means for prohibiting the operation of the driving force reduction control means when the high running load state is detected by the driving load detection means;
It is characterized by including.
[0012]
In the vehicle driving force control apparatus according to the invention of claim 3,
The driving force reduction control means is an actuator for driving the throttle valve. The throttle valve is moved to a fully open position and a fully closed position of a predetermined opening by displacement of the diaphragm according to the presence or absence of negative pressure introduced into the negative pressure working chamber. And a negative pressure diaphragm device that is driven by
[0014]
[Action]
According to the vehicle driving force control apparatus of the invention of claim 1,
Even when the slip state detection means detects the occurrence of slip of the drive wheel more than the extent that the drive force reduction control means is operated, the engine speed at the time of the slip is when the throttle valve is controlled to the fully closed position. When a high traveling load state is detected in which the engine output torque is greater than the rotational speed at which the engine output torque balances with the torque required to maintain the engine rotational speed, the driving force reduction control means is activated by the driving force reduction control prohibiting means. By being prohibited, the occurrence of engine braking can be prevented and the vehicle can be prevented from decelerating.
According to the vehicle driving force control device of the invention of claim 2,
Even when the slip state detection means detects the occurrence of slip of the drive wheel beyond the extent that the drive force reduction control means is actuated, the vehicle speed at the time of the slip is determined by the running resistance determined by the vehicle speed to fully close the throttle valve. When a high traveling load state that is higher than the vehicle speed when balancing with the driving force of the vehicle generated when the position is controlled is detected, the driving force reduction control prohibiting means prohibits the operation of the driving force reduction control means. The occurrence of engine braking is prevented, and deceleration of the vehicle can be prevented.
[0015]
Further, according to the driving force control apparatus for a vehicle according to the invention of claim 3, as a driving actuator of the throttle valve, using a negative pressure diaphragm device for driving a throttle valve in the fully closed position of the fully open position and the predetermined opening Therefore, it is the simplest and most reliable, which is advantageous in terms of cost.
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of the entire vehicle, and FIG. 2 is a system diagram of a drive device for a second throttle valve.
The intake device 2 of the engine 1 disposed horizontally in the FF vehicle is provided with a normally open second throttle valve 4 on the upstream side of the throttle valve 3 that is opened and closed in conjunction with the accelerator pedal. A fuel injection valve 31 is provided for each cylinder.
[0019]
On the other hand, wheel speed sensors 5A and 5B are provided on the left and right front wheels (drive wheels), respectively, and wheel speed sensors 6A and 6B are provided on the left and right rear wheels (driven wheels), respectively. Has been entered. The wheel speed detected by the wheel speed sensors 6A and 6B of the driven wheel can be used as a vehicle speed detection signal. In this case, one of the signals of the wheel speed sensors 6A and 6B may be used as the vehicle speed signal, but more precisely, the average value of the wheel speeds detected by the two wheel speed sensors 6A and 6B may be used as the vehicle speed signal. preferable.
[0020]
The traction control unit 7 detects the occurrence of slip based on the wheel speed difference between the driving wheel and the driven wheel, and generates a driving force reduction request signal when the slip occurs. One of the driving force reduction request signals is sent to a driving device (more specifically, a three-way electromagnetic valve 21 described later) for the second throttle valve 4, thereby driving the second throttle valve 4 in the valve closing direction. The other driving force reduction request signal is sent to the engine control module 8 to perform control such as fuel cut of the number of cylinders corresponding to the required reduction driving force. A rotation speed sensor 32 for detecting the engine rotation speed is provided, and the engine rotation speed signal is sent to the engine control module 8 to be used for various engine controls, and from the engine control module 8 to the traction control unit 7. And is used to determine whether or not the engine generates negative torque when the second throttle valve 4 is closed, as will be described later.
[0021]
Next, the drive device for the second throttle valve 4 will be described.
The second throttle valve 4 is a butterfly valve having a valve shaft 11 at a position eccentric from the center of the resin chamber 10 constituting the intake passage, and is opened and closed by operating a lever 12 fixed to the valve shaft 11. The lever 12 is provided with stoppers 13 and 14 for restricting the swing range thereof, so that the second throttle valve 4 is fully opened and fully opened to about 1/8. It takes a closed position.
[0022]
An output rod 17 connected to the diaphragm 16 of the negative pressure diaphragm device 15 is connected to the lever 12 of the second throttle valve 4.
The negative pressure diaphragm device 15 includes a negative pressure working chamber 18 defined by the diaphragm 16 and a spring 19 housed in the negative pressure working chamber 18 and biasing the diaphragm 16. When the pressure is introduced, the diaphragm 16 is displaced rightward in the drawing to drive the second throttle valve 4 to the fully closed position, and when the atmospheric pressure is introduced into the negative pressure working chamber 18, the diaphragm 16 is displaced leftward in the drawing. The second throttle valve 4 is returned to the fully open position.
[0023]
A three-way solenoid valve 21 for selectively introducing negative pressure or atmospheric pressure is connected to the communication path 20 to the negative pressure working chamber 18 of the negative pressure diaphragm device 15.
Three-way electromagnetic valve 21 is in the OFF state, it closes the suction port _{P 1,} open the atmospheric pressure side port _{P 2,} the ON state, conversely, to close the atmospheric pressure side port _{P 2,} the suction port _{P 1} To open.
[0024]
The negative pressure side port P ₁ of the three-way solenoid valve 21 is connected to a negative pressure tank 23 by a negative pressure introduction passage 22, and this negative pressure tank 23 is connected to an intake manifold (downstream of the throttle valve 3 in the intake passage 2) via a check valve 24. It is connected to the.
Atmospheric pressure side port P ₂ of the three-way electromagnetic valve 21 has been opened to the atmosphere by the atmospheric pressure introduction passage 25, the orifice 26 is provided in the atmospheric pressure introduction passage 25, which is one of operation time defining means .
[0025]
Thus, by using the negative pressure diaphragm device as a drive device for switching the second throttle valve 4 to two stages of full open and full close, a significant cost reduction can be achieved as compared with the conventional DC motor. Further, in addition to the negative pressure diaphragm device, for example, it may be constituted by a solenoid actuator that strokes a certain amount, and this can also be reduced in cost as compared with a DC motor.
[0026]
Next, the basic operation of the driving force reduction control means comprising the second throttle valve 4 and its driving device will be described.
During normal operation, the three-way solenoid valve 21 is OFF state, closes the suction port P _1, open the atmospheric pressure side port P _2. Therefore, the atmospheric pressure is introduced into the negative pressure working chamber 18 of the negative pressure diaphragm device 15, and the diaphragm 16 is displaced leftward in FIG. 1 by the spring 19 to hold the second throttle valve 4 in the fully open position. ing. The fully open position here is an opening that can secure the required engine air amount.
[0027]
On the other hand, the traction control unit 7 calculates the difference between the wheel speed detected by the wheel speed sensors 5A and 5B on the front wheel side and the wheel speed detected by the wheel speed sensors 6A and 6B on the rear wheel side. Exceeds the predetermined value, it is determined that slip has occurred, and a driving force reduction request signal is output.
This signal, three-way electromagnetic valve 21 is turned from the OFF state to the ON state, the three-way electromagnetic valve 21, closes the atmospheric pressure side port _{P 2,} opening the suction port _{P 1.} Therefore, negative pressure is introduced into the negative pressure working chamber 18 of the negative pressure diaphragm device 15, and the diaphragm 16 is displaced rightward in FIG. 1 against the urging force of the spring 19, so that the second throttle valve 4 is set to 1. Drives to the fully closed position of about / 8 opening.
[0028]
By setting the opening at the fully closed position to about 1/8, the opening is limited to a small opening necessary to suppress the slip and the engine stall is prevented.
Further, the operation time (t _{1 in} FIG. 3 ) from the fully open position to the fully closed position at this time includes slip on a low μ road due to the effective pressure receiving area of the diaphragm 16 and the diameter of the negative pressure introducing passage 22. In order to be able to hold down early, it is set to an extremely short time of 0.2 seconds or less.
[0029]
When the driving force is reduced by the closing operation of the second throttle valve 4 and the slip ratio is lowered, the driving force reduction request signal from the traction control unit 7 is canceled.
This signal cancellation, the three-way solenoid valve 21 is turned from the ON state to the OFF state, the three-way electromagnetic valve 21, closes the suction port P _1, opening the atmospheric side port P _2. Therefore, the atmospheric pressure is introduced into the negative pressure working chamber 18 of the negative pressure diaphragm device 15, the diaphragm 16 is displaced leftward in FIG. 1 by the spring 19, and the second throttle valve 4 is returned to the fully opened position.
[0030]
The operation time from the fully closed position to the fully open position (t _{2 in} FIG. 3 ) at this time is larger than the passage resistance of the negative pressure introduction passage 22 by providing an orifice 26 on the atmosphere introduction passage 25 side to increase the passage resistance. By doing so, it is set to 2 to 7 seconds, which is 10 times or more of the operation time from the fully open position to the fully closed position. This is set to a time during which an appropriate acceleration can be obtained after slip suppression while preventing a sudden occurrence of re-slip on the low μ road.
[0031]
Further, in this embodiment, when the negative pressure disappears for some reason, the inside of the negative pressure working chamber 18 of the negative pressure diaphragm device 16 becomes atmospheric pressure. At this time, the second throttle valve 4 takes the fully open position. . Therefore, it is possible to travel even when such a failure occurs.
Further, when the second throttle valve 4 becomes free due to the loss of the output rod 17 of the negative pressure diaphragm device 15, the valve shaft 11 of the second throttle valve 4 is provided eccentrically from the center of the intake passage. Thus, there is a difference in the pressure receiving areas of the left and right valve body parts across the valve shaft 11, so that even if the second throttle valve 4 is closed, the pressure difference between the upstream and downstream of the second throttle valve 4 (the downstream side is negative pressure). ), A moment in the valve opening direction acts on the second throttle valve 4. Therefore, even in the case of such a failure, the second throttle valve 4 is opened to allow traveling.
[0032]
Next, specific control that is executed in accordance with the traveling condition for (traction control) will be described with reference to the flowchart of FIG.
In step (denoted as S in the figure, the same applies hereinafter) 1, it is determined from the difference in wheel speed between the front wheels and the rear wheels as described above whether or not a slip of a predetermined level or higher at which traction control should be performed has occurred. If it is determined that no slip has occurred, the second throttle valve 4 is kept fully open in step 8 and the routine is terminated.
[0033]
The occurrence of the slip is detected, the process proceeds to step 2, the rotational speed sensor 32 engine rotation speed N detected by the determines whether it is less than the set rotational speed N _0.
Here, when the set rotational speed N ₀ is maintained at the fully closed opening (for example, 1/8 opening) of the second throttle valve 4 as described above, the intake negative pressure increases due to the increase of the engine rotational speed. and the engine torque decreases, the engine torque is set to the rotational speed when balanced with the torque required to maintain the engine rotational speed, therefore, the maintenance of the rotation is faster than the set rotational speed N ₀ The torque required for the above is insufficient and negative torque is generated (see FIG. 5 ).
[0034]
Therefore, when it is determined in step 2 that N> N ₀ , if the second throttle valve 4 is closed to the fully closed position as described above, negative torque is generated and engine braking is generated. In order to prevent this, the routine proceeds to step 8 where the second throttle valve 4 is kept fully open and this routine is terminated.
If it is determined in step 2 that N ≦ N _0, it is determined that there is room for traction control because engine braking due to the engine speed N itself does not occur even when the second throttle valve 4 is closed. Go to step 3.
[0035]
In step 3, the set vehicle speed Vo set for each gear ratio NT according to the gear ratio NT of the transmission is input. Here, the gear ratio NT may be detected by providing a gear ratio sensor. However, in an automatic transmission or the like, a gear shift is performed according to a gear shift pattern based on a throttle opening and a vehicle speed. Can also be detected. The set vehicle speed Vo is a running load that increases with an increase in the vehicle speed (specifically, the sum of the rolling resistance determined in advance by the product of the air resistance proportional to the square of the vehicle speed, the vehicle weight, and the rolling friction coefficient). Calculated) and the vehicle driving force determined by the output torque of the engine and the gear ratio NT when the second throttle valve 4 is closed to the fully closed position is set to the vehicle speed. Therefore, at a vehicle speed higher than the set vehicle speed Vo, the driving force of the vehicle falls below the traveling load, and engine braking occurs (see FIG. 6 ).
[0036]
Therefore, in step 4, the wheel speed sensor 6A, the detected wheel speed in either 6B, or whether the vehicle speed V is calculated as the average value of the wheel speed detected value is the predetermined vehicle speed V ₀ or less not Determine whether.
When it is determined in step 4 that V> V ₀ , as described above, if the second throttle valve 4 is closed to the fully closed position, the engine brake is generated. Is kept fully open to end this routine.
[0037]
Thus, in each of the above conditions, the operation of the driving force reduction control means is prohibited, so that the engine braking is not induced without the engine braking being induced, the spin feeling in the FR vehicle, the steering feeling deterioration in the FF vehicle, Tuck-in can be prevented and good running performance can be maintained.
As described above, the function of proceeding to step 8 by the determination in step 2 or the determination in step 4 and maintaining the second throttle valve 4 fully opened constitutes a driving force decrease control prohibiting means.
[0038]
If it is determined in step 4 that V ≦ V ₀ , even if the second throttle valve 4 is closed, the engine speed is not generated even if the second throttle valve 4 is closed. 21 is turned ON and the second throttle valve 4 is fully closed. That is, the second throttle valve 4 and its driving device and the function of step 4 constitute a driving force reduction control means.
[0039]
Further, the process proceeds to Steps 6 and 7, and second driving force reduction control is performed to control the number of cylinders that perform fuel cut with higher responsiveness than throttle opening control according to the slip state.
Specifically, a target value of slip that allows optimal travel is set, the required fuel cut amount C is calculated by PID control in accordance with the deviation ε from the slip detected in step 6, and the calculated value in step 7 Cut the number of cylinders corresponding to The required fuel cut amount C is calculated by the following equation.
[0040]
C = k _P · ε + k _I · ∫ ε dt + k _D · dε / dt, (k _P , k _I , k _D are gains of P, I, D)
In this way, when a slip occurs, the driving force can be reduced with a high response by the fuel cut, and then the control of the fuel cut is reduced by closing the second throttle valve 4 to prevent the exhaust temperature from becoming high. Thus, catalyst deterioration can be prevented. When the second throttle valve is opened, its speed is relatively slow, so that sudden occurrence of re-slip can be prevented and the number of fuel-cut cylinders is controlled to keep the slip close to the target value. It is possible to travel with a sufficient driving force.
[0041]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the engine rotation speed at the time of occurrence of slip is controlled to the fully closed position, the engine output torque is necessary for maintaining the engine rotation speed. When a high traveling load state that is higher than the rotational speed at which the torque is balanced is detected, the operation of the driving force reduction control means is prohibited, so that generation of engine braking due to generation of negative engine torque is prevented. Vehicle deceleration can be prevented.
According to the invention of claim 2, the vehicle speed at the time of occurrence of slip is greater than the vehicle speed when the running resistance obtained by the vehicle speed is balanced with the driving force of the vehicle generated when the throttle valve is controlled to the fully closed position. When the high running load state is detected, the operation of the driving force reduction control means is prohibited, so that the engine brake is prevented from being generated due to the negative engine torque and the vehicle can be prevented from decelerating.
[0042]
According to the invention of claim 3 , by using the diaphragm device as the driving source of the driving force reduction control means, it is possible to obtain the simplest, most reliable and low cost device .
[Brief description of the drawings]
[Figure 1] 1 is a system diagram of an entire vehicle showing an automatic transmission of the present invention.
FIG. 2 is a system diagram of a drive device for a second throttle valve in the embodiment.
FIG. 3 is a diagram showing operating time characteristics.
FIG. 4 is a flowchart showing an example of driving force control according to the embodiment.
FIG. 5 is a diagram showing the relationship between engine speed and engine torque when the second throttle valve is fully closed.
FIG. 6 is a diagram showing the relationship between the running resistance with respect to the vehicle speed and the driving force of the vehicle when the second throttle valve is fully closed.
FIG. 7 is a diagram showing the relationship between the running resistance with respect to the vehicle speed and the driving force of the vehicle when the second throttle valve is fully closed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Intake passage 3 Throttle valve 4 2nd throttle valve 5A, 5B Wheel speed sensor 6A, 6B Wheel speed sensor 7 Traction control unit 8 Engine control module 10 Chamber 15 Negative pressure diaphragm apparatus 31 Fuel injection valve 32 Rotational speed sensor

Claims (3)

A throttle valve disposed in the intake passage of the engine and controlled to be switched in two stages, a fully open position and a fully closed position of a predetermined opening;
Slip state detecting means for detecting the slip state of the drive wheels of the vehicle;
Driving force reduction control means for reducing the driving force of the vehicle by controlling the throttle valve to a fully closed position in accordance with the detected slip state;
When the throttle valve is controlled to the fully closed position, a rotation speed is set when the engine output torque is balanced with a torque necessary to maintain the engine rotation speed, and the engine rotation speed when the slip occurs is set as described above. Traveling load detecting means for detecting a high traveling load state when the rotation speed is greater than
Driving force reduction control prohibiting means for prohibiting the operation of the driving force reduction control means when the high running load state is detected by the driving load detection means;
A vehicle driving force control device comprising: A throttle valve disposed in the intake passage of the engine and controlled to be switched in two stages, a fully open position and a fully closed position of a predetermined opening;
Slip state detecting means for detecting the slip state of the drive wheels of the vehicle;
Driving force reduction control means for reducing the driving force of the vehicle by controlling the throttle valve to a fully closed position in accordance with the detected slip state;
A vehicle speed at which the running resistance determined by the vehicle speed is balanced with the driving force of the vehicle generated when the throttle valve is controlled to the fully closed position is set, and the vehicle speed at the time of occurrence of slip is larger than the set vehicle speed. a running load detecting means for detecting a high running load condition,
Driving force reduction control prohibiting means for prohibiting the operation of the driving force reduction control means when the high running load state is detected by the driving load detection means;
A vehicle driving force control device comprising: The driving force reduction control means, as the actuator for driving the throttle valve , opens the throttle valve to a fully open position and a fully closed position of a predetermined opening by displacement of a diaphragm according to the presence or absence of negative pressure introduced into the negative pressure working chamber. driving force control apparatus for a vehicle according to claim 1 or claim 2, characterized in that it comprises a negative pressure diaphragm device which drives the and.

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