JPH04365957A - Control device of engine for vehicle - Google Patents

Abstract

PURPOSE:To carry out good traction control having good responsiveness and convergence property by detecting abrasion coefficient on a running road surface while detecting change of an axial torque in a driving wheel, and controlling engine torque or the like while setting a target torque on the basis of the abrasion coefficient or the like. CONSTITUTION:Axial torque of a driving wheel and torque of an engine in a vehicle are detected by respective means (A), (B), while abrasion coefficient on a running road surface is calculated by a means (C) when the axial torque is reduced when the engine torque is not reduced. Target torque far traction control is set by a means (D) on the basis of the abrasion coefficient or the like, while the basic control amount of throttle valve opening in response to the target torque is set by a means (E). The feed back, control amount of the throttle valve opening is set by a means (F) on the basis of deviation between the target torque and the engine torque. The throttle valve opening is controlled by a means (G) so as to approach the engine torque to the target torque, in response to a based control amount and a feed back control amount.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to so-called traction control, which controls engine torque to be maintained at an optimum slip ratio by reducing engine torque when the wheels slip significantly against the road surface during acceleration. The present invention relates to an engine torque control device.

0002

[Prior art] Accelerator pedal operation amount (depression amount)
There is a system that detects the amount of operation and uses an actuator to drive and control a throttle valve installed in the engine's intake system according to the amount of operation.In particular, when wheel slip is detected, engine torque is reduced, and then gradually increased. There are some that perform traction control that maintains the driving force at an optimal level while suppressing slip by performing integral control (see Japanese Patent Laid-Open Publication No. 1-218932, etc.).

0003

By the way, in such a conventional traction control device, for example, the throttle valve opening degree, ignition timing, etc. are controlled so that the slip ratio of the wheels becomes a target slip ratio. For example, when performing feedback control using the throttle valve opening, the control opening is determined using the following calculation formula.

[0004] θ= Ki ∫ (St −S) dt+ Kp (St
-S)+K However, θ: Target throttle valve opening Ki: Integral gain St: Target slip ratio S: Actual slip ratio Kp: Proportional gain K: Constant However, in such conventional traction control, the occurrence of slip is caused by excessive engine torque, and although traction control is performed by controlling engine torque, the control amount is set according to the deviation between the target slip rate and the actual slip rate. As a result, there is a large response delay due to a delay in detecting the slip ratio, and the relationship between the slip ratio and engine torque is non-linear, making it difficult to match the gain, making it difficult to maintain good convergence over the entire operating range. The problem was that it was difficult.

The present invention has been made in view of the above-mentioned conventional problems, and sets a target torque corresponding to a target slip ratio of engine torque, which is a slip generating factor, and
It is an object of the present invention to provide an engine torque control device capable of performing traction control with excellent responsiveness by performing feedback control to approach the target torque.

[0006]

[Means for Solving the Problems] Therefore, as shown in FIG. 1, the vehicle engine control device according to the present invention includes an axial torque detection means for detecting the axial torque of the drive wheels of the vehicle, and an axial torque detection means for detecting the axial torque of the driving wheels of the vehicle. an engine torque detection means for detecting torque; and when the shaft torque decreases while the detected engine torque is not decreasing, the friction coefficient of the running road surface is determined based on the detected value of the shaft torque immediately before the decrease and the specifications of the vehicle. A friction coefficient calculation means for calculating a friction coefficient, a traction control target torque setting means for setting a target torque of the engine based on the detected friction coefficient of the running road surface or a value related thereto, and a traction control target torque setting means for setting the set target torque for traction control. Basic control amount setting means for setting the basic control amount of the throttle valve opening as an initial control value, and setting a feedback control amount of the throttle valve opening based on the deviation between the set target torque and the detected engine torque. The present invention includes a feedback control amount setting means, and a throttle valve opening control means for controlling the throttle valve opening so that the engine torque approaches the target torque based on the set basic control amount and the feedback control amount.

As shown in FIG. 2, the present invention also includes shaft torque detection means, engine torque detection means, friction coefficient calculation means, and traction control target torque setting means similar to those described above, and also includes ignition control means for setting the set target torque for traction control. a basic control amount setting means for setting a basic control amount for timing as an initial control value; and a feedback control for setting a feedback control amount for ignition timing based on a deviation between a set target torque for traction control and detected engine torque. The ignition timing control means may include an amount setting means and an ignition timing control means for controlling the ignition timing so that the engine torque approaches the target torque based on the set basic control amount and feedback control amount.

Furthermore, as shown in FIG. 3, a vehicle equipped with an automatic transmission equipped with a torque converter is equipped with shaft torque detection means, engine torque detection means, and friction coefficient calculation means similar to those described above, and also has the following features: traction control target torque setting means for setting a target torque of the output shaft of the engine based on a friction coefficient or a value related thereto; output shaft rotation speed detection means for detecting the rotation speed of the output shaft of the torque converter; A target engine rotation speed setting means for setting a target engine rotation speed based on a set target torque and a detected output shaft rotation speed of the torque converter; The engine rotation speed control means may be configured to include an engine rotation speed control means for controlling control parameters of the engine.

[0009]

[Operation] When the engine torque detected by the engine torque detecting means increases or remains constant, if the driving wheels are not slipping, the shaft torque does not decrease, but if the driving wheels slip, the shaft torque decreases. Note that the detection of the engine torque by the engine torque detection means does not require the provision of a special sensor (although it may be provided), and may be performed by estimating the amount of fuel injected into the engine separately.

Therefore, when the shaft torque detecting means detects a decrease in the shaft torque under the above conditions, it is possible to detect that the driving wheels have slipped, and the value of the shaft torque that reaches the maximum just before this is the difference between the driving wheels and the road surface. It is equal to the value obtained by multiplying the maximum frictional force generated by the wheel diameter of the drive wheels, and since the maximum frictional force is determined by the vehicle specifications (weight) and the friction coefficient of the road surface, the maximum shaft torque is known. The friction coefficient of the road surface can be determined by back calculation.

[0011] Once the friction coefficient of the road surface is determined by the friction coefficient calculation means, the engine torque that causes the drive wheels to slip can be calculated backwards, and from this, engine traction control can be performed to obtain the optimum slip ratio that maintains the maximum propulsion force of the vehicle. You can set the target torque for use. The throttle valve opening degree is controlled to obtain the target torque for traction control set by the target torque for traction control setting means.

[0012] Therefore, the basic control amount setting means sets the basic control amount for the target torque as an initial value based on the current engine condition, specifically, the rotation speed, etc., and the basic control amount and the feedback control amount setting means set the basic control amount for the target torque as an initial value. The throttle valve opening degree control means or the ignition timing control means feedback-controls the throttle valve opening degree and the ignition timing based on the feedback control amount set based on the torque deviation.

[0013] By setting the initial value in this way, the amount to be corrected by feedback control is reduced, and the feedback gain can be reduced, so that responsiveness can be ensured while maintaining control stability. can. When performing feedback control using a target slip ratio as in the past, it is difficult to determine the throttle valve opening and ignition timing as initial values. The initial value can be easily determined from the engine performance.

In addition, in a vehicle equipped with an automatic transmission equipped with a torque converter, when the rotation speed of the output shaft of the torque converter is known, the engine The engine speed to obtain the target torque is determined. Therefore, the target rotation speed setting means sets the engine rotation speed as a target rotation speed, and feedback control is performed by engine rotation speed control so that the engine rotation speed approaches the target rotation speed. When controlling using the engine speed, it is not necessary to use the engine torque when setting the feedback control amount, so there is no need to know the exact engine torque when detecting (including estimating) the engine torque using the engine torque detection means. Rough detection is enough to know whether the engine torque is increasing or decreasing.

[0015]

[Examples] Examples of the present invention will be described below. In FIG. 4 showing the system configuration of one embodiment, a throttle valve 4 driven by an actuator 3 such as a step motor is interposed in an intake passage 2 of an engine 1 mounted on a vehicle.

Normally, the control unit 5 sets a target torque for the engine 1 according to the operation amount (depression amount) of an accelerator pedal (not shown), which is usually detected by an accelerator sensor 6, and adjusts the engine torque to the target. An opening control signal is output from the control unit 5 to the actuator 3 in order to approach the torque, and the opening of the throttle valve 4 is controlled via the actuator 3 by this signal. When a rear wheel 7 slips, a friction coefficient μ of the road surface is detected based on a signal from a torque sensor 8, which serves as shaft torque detection means for detecting shaft torque, and traction control, which will be described later, is performed in accordance with the friction coefficient μ.

Further, an automatic transmission 9 with a torque converter is connected to the output shaft of the engine 1, and the automatic transmission 9 includes a gear ratio sensor 10 for detecting the gear ratio and a rotation speed of the output shaft of the torque converter. A rotation speed sensor 11 is installed as an output shaft rotation speed detection means for detecting the rotation speed of the output shaft, and signals from the gear ratio sensor 10 and rotation speed sensor 11 and a signal from the crank angle sensor 12 for detecting the engine rotation speed are also connected to the control. input into unit 5. The rotation speed of the output shaft of the torque converter is determined by detecting the rotation speed of the propeller shaft and the rotation speed of the rear wheels (preferably the average value of the rotation speed of the left and right rear wheels), and from these and the gear ratio. You can also do this.

The detection of the friction coefficient μ by the control unit 5 and the engine torque control according to the first embodiment based on the detected value will be explained below with reference to the flowchart shown in FIG. In FIG. 5 showing engine torque control, step (denoted as S in the diagram; the same applies hereinafter) 1
Now, the first target torque T1 is set according to driving conditions including the amount of operation of the accelerator pedal. In step 2,
Shaft torque TR of rear wheel 7 detected by torque sensor 8
Q is A/D converted.

In step 3, engine torque Te is calculated. This is determined as a value proportional to the basic fuel injection amount TP (=K·Q/N; K is a constant, Q is the intake air flow rate, and N is the engine speed), which is determined in a separate routine. The function of step 3 corresponds to the engine torque detection means. In step 4, it is determined whether the engine torque Te is decreasing.

If the determination in step 4 is NO, that is, if the engine torque Te is monotonically increasing, the process proceeds to step 5, where it is determined whether or not the shaft torque TQR has decreased. If the determination in step 5 is YES, that is, if the shaft torque TRQ decreases while the engine torque Te is monotonically increasing, the process proceeds to step 6, where it is determined whether this state is the first time.

If it is determined in step 6 that this is the first time, it is determined that the shaft torque TRQ has decreased as a result of slippage in the rear wheels 7, and the previous shaft torque detection value TRQ-
Since 1 is the maximum shaft torque that can be generated with respect to the friction coefficient μ of the current road surface, μ is calculated backwards in step 7 using the following equation. The function of step 7 corresponds to a friction coefficient calculation means.

μ=4·TRQ-1/(R·W·g) where R is the radius of the rear wheel 7, W is the vehicle weight, and g is the gravitational acceleration. Next, the process proceeds to step 8, where a second target torque T2 for traction control is set for the friction coefficient μ obtained in step 7 using the following equation. The function of step 8 corresponds to a target torque setting means for traction control.

[0023]T2 =Ks・μ・R・W・g/ (4
・i) However, Ks is a constant that can be freely changed based on the longitudinal propulsion force and cornering force of the vehicle, and is a constant that can be freely changed based on the longitudinal propulsion force and cornering force of the vehicle. , is set to a moderate value smaller than 1. Further, i=final gear ratio×(gear ratio of automatic transmission)×(torque ratio of torque converter).

Next, in step 9, the magnitude of the first target torque T1 for the accelerator operation amount obtained in step 1 and the second target torque T2 for traction control obtained in step 9 is compared and determined, When T1 ≦T2, proceed to step 10, select T1, and set T1 > T2.
In this case, the process proceeds to step 11, where T2 is selected and set as the target torque T to be output.

In step 12, the target torque T and
Based on the current engine rotational speed Ne detected by a crank angle sensor or the like, a target throttle valve opening θ0 corresponding to the target torque is set by searching from a preset map (see FIG. 6 for characteristics). The target throttle valve opening θ0 is a basic control amount and becomes an initial value of feedback control. That is, the function of step 12 constitutes basic control amount setting means.

In step 13, the actuator 3 is driven to control the opening θ of the throttle valve 4 to the target throttle valve opening θ0. Next, in step 14, a deviation ΔT between the target torque T and the detected engine torque Te is calculated, and the throttle valve 4 is adjusted according to the deviation ΔT.
The feedback control amount Δθ is set. The function of step 14 corresponds to feedback control amount setting means.

Specifically, the feedback control amount Δθ is determined by the following equation. Δθ= Ki ∫ (T- Te ) dt + Kp (
T-Te) However, K i : integral gain K p : proportional gain K : constant In step 15 , the actuator 3 performs feedback control so that the opening degree θ of the throttle valve 4 becomes θ0 + Δθ. Therefore, the actuator 3 and the function of step 15 correspond to throttle valve opening control means.

[0028] In this way, the friction coefficient μ of the running road surface
It is possible to accurately detect the friction coefficient μ or a value related thereto (TRQ-1, etc.) to perform traction control corresponding to the road surface, and also to set a target torque and respond to the target torque. Since the target throttle valve opening is set as the initial value and feedback control is performed according to the deviation between the target torque and the actual torque, it has excellent responsiveness and has good linearity between torque and throttle valve opening control amount. Since the control is performed, the integral gain K i
and proportional gain K p can be matched over the entire operating range, and has excellent convergence.

As described above, by changing the constant Ks according to cornering conditions, traction control can be performed to maintain an optimum slip ratio even under different cornering conditions. Furthermore, although this embodiment shows an engine equipped with only one throttle valve, it is equipped with a main throttle valve that is mechanically linked to accelerator operation, and a sub-throttle valve whose opening is controlled by an actuator, and the sub-throttle valve is always operated. Traction control in which the throttle valve is fully opened and the sub-throttle valve is closed when a wheel slip occurs is also common, and it goes without saying that the present invention can also be applied to this control. In that case, compare the control opening of the sub-throttle valve corresponding to the target torque for traction control obtained in the same way as above and the detected opening of the main throttle valve, and if the former is smaller, The configuration may be such that the sub-throttle valve is throttle-controlled.

Exactly the same control can be performed by controlling the ignition timing instead of controlling the throttle valve opening. Regarding the control routine of this embodiment, the description of the control routine will be omitted since it only changes the throttle valve opening θ to the ignition timing in the flowchart of FIG. Incidentally, in order to reduce the torque during traction control, the ignition timing is retarded, and the relationship between the amount of torque reduction and the amount of retardation of the ignition timing is shown in FIG. The same goes for setting the target ignition timing corresponding to the target throttle valve opening based on the target torque and the current engine speed.

Therefore, in such ignition timing control, traction control with excellent responsiveness and convergence can be performed. Next, a control routine of a third embodiment in which the engine speed is feedback-controlled based on the output shaft speed of the automatic transmission with torque converter 9 will be described with reference to FIG.

Regarding steps 21 to 31,
Since it is the same as steps 1 to 11 in FIG. 5, the explanation will be omitted. In step 32, a target engine speed Net is set based on the target torque T of the engine and the output shaft Nt of the torque converter. This is obtained as follows. The torque ratio t and torque capacity coefficient τ of the torque converter are the rotational speed ratio e (= Nt/Ne) of the input and output shafts of the torque converter, as shown in Fig. 9.
Determined by Further, the input shaft torque, that is, the engine torque Te is determined as Te = t·τ·Ne 2 . Therefore, when the engine torque is the target torque T, the target engine speed Net is the target torque T
is determined as a function of the output shaft rotation speed Nt. This relationship is as shown in FIG. Therefore, the target engine speed Net is set by searching from a map having the characteristics shown in FIG.

In step 33, a feedback control amount Δθ of the throttle valve opening θ is set according to the deviation ΔN between the target engine speed Net and the engine speed Ne detected by the crank angle sensor 12, and in step 34 Then, the throttle valve 4 is driven by the feedback control amount Δθ via the actuator 3 to control the opening degree θ. When control is performed using engine speed as in this embodiment, there is no need to use engine torque when setting the feedback control amount Δθ in step 33, and the engine torque detection means detects (including estimates) the engine torque. For this, a rough detection is enough to know whether the engine torque increases or decreases in step 24.

Furthermore, in the case of the engine speed control method, the same effect can be obtained even if ignition timing control is used instead of throttle valve opening control.

[0035]

As explained above, according to the present invention, the friction coefficient of the running road surface is detected while detecting the change in the shaft torque of the driving wheels, and the target torque is determined using the friction coefficient or a value related thereto. It is possible to perform good traction control with excellent responsiveness and convergence by controlling the engine torque or engine speed by setting the throttle valve opening and ignition timing.

[Brief explanation of drawings]

[Fig. 1] Block diagram showing the configuration of the first invention

[Fig. 2] Block diagram showing the configuration of the second invention

[Fig. 3] Block diagram showing the configuration of the third invention

[Figure 4] System diagram showing one embodiment of the present invention

[Fig. 5] Flowchart showing engine torque control in the embodiment same as above.

[Fig. 6] Map for setting the target throttle valve opening in the embodiment same as above.

[Fig. 7] Map showing the relationship between the ignition timing control amount and the torque reduction rate in the second embodiment

[Fig. 8] Flowchart showing engine rotation speed control of the third embodiment.

[Figure 9] Map showing torque converter characteristics

[Figure 10
] Map for setting the target engine speed in the third embodiment

[Explanation of symbols]

1 Engine 2 Intake passage 3 Actuator 4 Throttle valve 5 Control unit 7 Rear wheel 8 Torque sensor 9 Automatic transmission 11 Output shaft rotation sensor

Claims (3)

[Claims] 1. Shaft torque detection means for detecting the shaft torque of a drive wheel of a vehicle; engine torque detection means for detecting the torque of an engine mounted on the vehicle; At times, a friction coefficient calculating means for calculating the friction coefficient of the running road surface based on the detected value of the shaft torque immediately before the decrease and the specifications of the vehicle, and a friction coefficient calculating means for calculating the friction coefficient of the running road surface based on the detected value of the shaft torque immediately before the reduction and the specifications of the vehicle; a traction control target torque setting means for setting a target torque of the engine; a basic control amount setting means for setting a basic control amount of the throttle valve opening corresponding to the set traction control target torque as a control initial value; feedback control amount setting means for setting a feedback control amount of the throttle valve opening based on the deviation between the detected target torque and the detected engine torque; 1. A control device for a vehicle engine, comprising: a throttle valve opening control means for controlling the throttle valve opening so as to approximate the torque. 2. Shaft torque detection means for detecting the shaft torque of a drive wheel of a vehicle; engine torque detection means for detecting the torque of an engine mounted on the vehicle; At times, a friction coefficient calculation means for calculating the friction coefficient of the running road surface based on the detected value of the shaft torque immediately before the decrease and the specifications of the vehicle, and a traction control target torque setting means for setting a target torque of the engine; a basic control amount setting means for setting a basic control amount of ignition timing corresponding to the set traction control target torque as a control initial value; Feedback control amount setting means for setting a feedback control amount for ignition timing based on the deviation between the target torque for traction control and the detected engine torque; 1. A control device for a vehicle engine, comprising: ignition timing control means for controlling ignition timing so as to approach the ignition timing. 3. A vehicle equipped with an automatic transmission with a torque converter, comprising: shaft torque detection means for detecting the shaft torque of the drive wheels of the vehicle; engine torque detection means for detecting the torque of the vehicle-mounted engine; Friction coefficient calculating means for calculating a friction coefficient of a running road surface based on a detected value of the shaft torque immediately before the reduction and vehicle specifications when the shaft torque decreases while the engine torque is not decreasing; traction control target torque setting means for setting the target torque of the engine based on the friction coefficient of the torque converter or a value related thereto; and output shaft rotation speed detection means for detecting the rotation speed of the output shaft of the torque converter. target rotation speed setting means for setting a target rotation speed of the engine based on the detected target torque and the detected output shaft rotation speed of the torque converter; and control of the engine so that the engine rotation speed approaches the set target rotation speed. A control device for a vehicle engine, comprising: engine rotation speed control means for controlling parameters.