JP2705112B2 - Control device for internal combustion engine for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for appropriately changing the characteristics of an internal combustion engine for a vehicle in accordance with the driving state of the vehicle and always obtaining good driving performance.

<Conventional Technology> There are the following control devices for a conventional internal combustion engine for a vehicle.

As a method for making the torque characteristics and output characteristics of the engine with respect to the accelerator operation preferable characteristics of the drivability of the vehicle, for example, as disclosed in JP-A-60-1922843, according to the accelerator operation amount and the engine rotation speed, There is a device that determines a throttle valve opening and drives the throttle valve so as to match the set opening.

Japanese Patent Laid-Open Publication No. Sho 62-193151 discloses a governor for a diesel engine which is controlled in the same manner.

As an example in which the control mode of the engine output adjusting means is switched in accordance with the driving state of the vehicle so as to obtain the drivability desired by the driver under various other driving conditions, see, for example, There is something like that shown in 25355.

<Problems to be Solved by the Invention> However, in such a conventional control apparatus for a vehicle internal combustion engine, the torque of the engine, which is a physical quantity directly acting on the control of the vehicle, is not used as a reference quantity for the control, and the torque The control is performed using the throttle valve opening, which is an indirect control amount to control the engine, as a reference amount of control, so that the engine is not affected by changes in the external load applied to the engine determined by the vehicle weight and the gear ratio of the transmission. It is not possible to constantly adjust the torque characteristics to maintain a constant steering feeling.

Further, in a conventional fuel supply system that supplies a fuel by detecting a change in the intake air amount, a required torque cannot be instantaneously generated.

The present invention has been made in view of such a conventional problem, and controls the engine torque to a target value in consideration of the output characteristic of the engine that changes due to an external load applied to the engine. It is an object of the present invention to provide a control device for a vehicle internal combustion engine that solves the above.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention provides a rotational speed detecting means for detecting a rotational speed of an engine, an accelerator operation amount detecting means for detecting an accelerator operation amount, and a vehicle. Vehicle weight detection means for detecting weight; reduction gear ratio detection means for detecting a reduction ratio (engine rotation speed / wheel rotation speed); based on the detected accelerator operation amount, engine rotation speed, vehicle weight, and reduction ratio. Target torque calculating means for calculating the target torque of the engine according to the following equation: T ₀ = K 1 · W / m · a-K 2 · W / m ² · Ne where T ₀ : target torque, W: vehicle weight, m ; Deceleration ratio, a; accelerator opening, Ne; engine rotation speed, K1, K2; constant fuel supply amount control means for controlling the fuel supply amount to the engine according to the calculated target torque. Intake air amount control that controls the amount of intake air to the engine according to the target torque A configuration comprises a stage, a.

<Operation> The rotation speed detection means detects the engine rotation speed, the accelerator operation amount detection means detects the accelerator operation amount, and the external load detection means detects the external load applied to the output shaft of the engine based on the vehicle weight, gear ratio, etc. Is detected.

The target torque calculating means calculates a target torque of the engine based on the detected accelerator operation amount, engine speed and external load.

The fuel supply amount control means controls the fuel supply amount according to the calculated target torque, and the intake air amount control means also controls the intake air amount according to the target torque.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 2 showing the configuration of one embodiment, a crank angle sensor 1 as a rotation speed detecting means for detecting a crank angle and a rotation speed of an engine (not shown), and an operation amount (depressed amount) of an accelerator pedal is determined by an output voltage of a potentiometer. An accelerator opening sensor 2 as an accelerator operation amount detecting means for detecting, a stroke sensor 3 for detecting a sinking amount of a vehicle suspension by an output voltage of a potentiometer, and a gear position sensor 5 for detecting a gear position (shift position) of the transmission 4. The detection signals from these sensors are provided to the CPU 6A of the microcomputer.

Here, since the stroke sensor 3 and the gear position sensor 5 can detect the external load applied to the output shaft of the engine from these detection signals, they constitute an external load detecting means.

The CPU6A, the calculates a target torque on the basis of the detection signals, a fuel injection amount necessary for outputting the target torque (supply amount) is read from the fuel injection amount table 6B _1, which corresponds to A fuel injection pulse having a pulse width is output to an injector 7 provided in an intake passage of the engine to perform fuel supply control. Similarly, by reading a target throttle valve opening providing the intake air amount necessary for the target torque output from the throttle valve opening degree table 6B _2, and outputs to the servo drive circuit 8, and controls the intake air quantity.

That is, the CPU 6A has both fuel supply control means and intake air amount control means.

Further, the CPU 6A simultaneously performs an ignition control for outputting an ignition signal to the ignition coil 12 based on the crank angle signal from the crank angle sensor 1.

The fuel injection amount table 6B ₁ stores data of the fuel injection amount in the ROM 6B so that the fuel injection amount necessary to generate the target torque can be read by giving the target torque and the engine speed _every moment. Similarly, the throttle valve opening degree table 6B ₂ also stores the intake air amount data in the ROM 6B so that the intake air amount required to generate the target torque can be read out by giving the momentary target torque and the engine speed. Have been.

The servo drive circuit 8 includes a throttle sensor for detecting an opening degree of a throttle valve 10 interposed in an intake passage 9 of the engine.
11 and the actual throttle valve opening theta _R detected by the
The servo motor 12 connected to the throttle valve 10 is driven forward and reverse in accordance with the deviation from the target throttle valve opening θ ₀ input from the CPU 6A, so that the opening of the throttle valve 10 follows the target value. .

Next, the control of the engine by the CPU 6A will be described with reference to FIGS.
The description will be made according to the flowchart shown in FIG.

FIG. 3 shows a routine for performing each calculation of the target torque, the fuel injection amount, and the target throttle valve opening, and is executed at regular intervals, for example, every 10 ms.

In P _1, the accelerator opening (the operation amount) from an accelerator opening sensor 2 reads a.

In P _2, based on the crank angle signal from the crank angle sensor 1 calculates the engine speed N _e.

In P _3, it calculates a target torque T ₀ according to the following equation.

T ₀ = k ₁ · a−k ₂ · N _e (1) k ₁ and k ₂ are parameters for determining the characteristics of the output torque of the engine, and k ₁ is a proportional coefficient of the accelerator opening to the output torque of the engine. , k ₂ is the proportional coefficient of engine speed versus output torque,
It is set according to the external load applied to the output shaft of the engine, which is detected by the weight of the vehicle and the gear ratio of the transmission by a routine described later.

In P _4, and the engine rotational speed speed N _e calculated in P _2, the target torque T ₀ becomes calculated by P _3, the fuel injection amount table 6B ₁
Read a basic injection pulse width T _P of fuel from. Here, the fuel injection amount table and reads the data of the basic injection pulse width T _P and a target torque T ₀ and the engine rotational speed N _e as shown in FIG. 6, the data, onboard engine in a vehicle It is data determined from the performance of

In P _5, the basic injection pulse width T _P obtained in P _4, by performing various corrections determined in accordance with the operating state of the engine, it calculates the fuel injection pulse width T _1.

Here, the correction applied to the basic injection pulse width T _P, those feedback correction and the like of the known air-fuel ratio is performed based on the increase, increasing at the time of starting, detection of exhaust oxygen concentration according to the coolant temperature .

In P _6, by the target torque T ₀ calculated by the engine speed N _e and P _3, which is calculated by P _2, the throttle valve opening table
It reads the target throttle valve opening theta ₀ from 6B _2.

Throttle valve opening table 6B ₂ is designed to read the target throttle valve opening theta ₀ and a target torque T ₀ and the engine rotational speed N _e as shown in FIG. 5, from the inherent performance of the onboard engine of the vehicle It is data determined.

In P _7, and sets the fuel injection pulse width T ₁ calculated at P ₅ to the output port of the CPU 6a.

Thus, the fuel injection pulse having a pulse width of the T ₁ at a predetermined timing triggered by the crank angle signal from the crank angle sensor 1 is outputted to the injector 7, the fuel in an amount corresponding to T ₁ is injection-supplied You.

In P _8, and outputs a target throttle valve opening theta ₀ which is P ₆ calculation to the servo drive circuit 8. This allows the throttle valve
10 is feedback-controlled to be driven to the servo motor 12 coincides with the target throttle valve opening theta _0.

4 shows a routine for setting the output torque characteristics of the engine used in the calculation of P ₃ in Figure 3. This routine does not need to be constantly operated at a high speed as in the fuel supply control and intake air amount control routines shown in FIG. 3, and is executed at every gear shift or in a background job of the microcomputer to avoid wasting the operation time. ing.

In P _11, it reads the gear position of the transmission 4.

P In ₁₂ to P _13, to determine the gear position, P ₁₄ to P ₁₆ in the gear ratio data M ₁ of the first speed stored in the ROM6B respectively, the second speed gear ratio data M _2, 3-speed gear ratio data reads the M _3, and stores the gear ratio of the current shift position in register m.

In P _17, it calculates the vehicle weight W according to the following equation from the sinking amount of the suspension detected by the stroke sensor 3.

W = W ₀ + l / k (2) where W ₀ is the weight of the body only, which is known in advance, l is the amount of suspension of the suspension caused by the load of the occupants or the load, and k is the spring of the suspension. Is a constant.

The proportional coefficient k ₁ to set the characteristics of the accelerator opening versus output torque P _18, is calculated by the following equation.

k ₁ = K ₁ · W / m (3) At P ₁₇ , a proportional coefficient k ₂ for setting the characteristic of the engine speed versus the output torque is calculated by the following equation.

k ₂ = K ₂ · W / m ² (4) Here, m is the transmission gear ratio (reduction ratio), and K ₁ and K ₂ are the best vehicle operating sensations determined in advance through experiments and the like. It is a constant obtained.

 Next, the operation of this embodiment will be described with reference to FIG.

FIG. 7 shows a model of the motion of the vehicle, in which the power loss of the engine and the drive train is omitted, and is the simplest representation. The relation of the acceleration α of the vehicle body when the accelerator opening a changes in this model is as follows.

Here, R is the effective radius of the tire, W is the vehicle weight, D is the running resistance, and S is the Laplace operator. Here, the running resistance D is
As described above, it is a value obtained by adding the rolling resistance and the air resistance, and the rolling resistance is a value that varies depending on the total weight of the vehicle and the air resistance, and therefore, precisely taking these values into consideration. Although it is a calculated value, it is sufficient to use an average value corresponding to the average running as the running resistance D used for the target torque calculation.

The first term on the right side of the above equation (5) indicates the response of the acceleration α of the vehicle body to the accelerator opening a, and the second term indicates the response of the acceleration α of the vehicle body to the running resistance D. Determines sensation.

G ₁ = k ₁ · m / R · g / W (6) G ₂ k ₂ · m ² / R ² · g / W (7) G ₃ = g / W (8) where , G is the gravitational acceleration.

As shown in the conventional example, when changing the rate of change of the actual throttle valve opening degree with respect to the accelerator opening, (6) k ₁ is changed in type, for example, the k ₁ larger accelerator opening and the gain G ₁ is larger The change in the acceleration α with respect to the change in the degree “a” becomes large, resulting in a powerful steering feeling.

Moreover, the differential effect G ₂ is large, that is, maneuverability appear acts to amplify the change worse. K ₂ involved in G ₂ in equation (7)
Corresponds to the slope tan δ of the torque curve of the engine as shown in FIG. 7, and in the method of changing the throttle valve opening only in accordance with the accelerator opening, k ₂ takes a characteristic value peculiar to the engine. It cannot be changed.

In the method of the present invention are to be set freely a value of k ₂ by a method for computing a target torque of the engine by the accelerator opening and the engine rotational speed.

The gains G ₁ and G ₂ that determine the steering feeling of the vehicle have values that provide the best filling, and can be experimentally matched by the engine characteristics k ₁ and k ₂ and the variable element of the gear ratio m.

However, if there is no means for changing k ₁ and k ₂ according to the external load applied to the engine determined by the vehicle weight W and the gear ratio m as in the conventional example, even if the matching is achieved at a certain gear ratio, The best G ₁ and G _{2 when} changing gears
The feeling gets worse. For example, when the low-speed gear (m large) is a phenomenon G ₂ in proportion to the square is generated well become greater becomes jerky was poor maneuverability of m as in equation (7). Similarly, the vehicle weight W also affects G ₁ and G ₂ .

Now, with gear ratio m ₀ and vehicle weight W ₀ , the best values k ₁ and k ₂ of k ₁ and k ₂ are k ₁₀ and k
_Assuming that ₂₀ is experimentally obtained, the following relationship is established.

G ₁ = k ₁₀ · m ₀ / R · g / W ₀ …… (9) G ₂ = k ₂₀ · m ₀ ² / R ² · g / W ₀ …… (10) Gear ratio m and vehicle weight W When it changes, in the expressions (6) and (7), k ₁ = k ₁₀ · m ₀ / W ₀ · W / m = k ₁ · W / m (11) k ₂ = k ₂₀ · m ₀ ² / W ₀ · W / m ² = k ₂ · W / m ² ... (12) If the values of k ₁ and k ₂ are set according to m and W, the gains G ₁ and G ₂ are always ( The best values shown in equations (9) and (10) can be obtained.

In the present embodiment, the target throttle valve opening θ ₀ is output to the servo drive circuit 8 as a means for controlling the intake air amount according to the target torque, but other methods, for example, according to the target throttle valve opening θ ₀ The suction negative pressure may be output as a target value, and the servo mechanism may be operated so that the suction negative pressure becomes the target value.

The present embodiment has the following effects in addition to the above effects.

The method of fuel supply control is to use the amount of air taken into the cylinder as the load equivalent value, determine the intake air flow rate, the suction negative pressure, and the engine speed, and supply the required fuel amount in proportion to the cylinder intake air amount. Is generally performed.

However, in such a method, the detection delay of the sensor,
There is a transportation delay time from the injection of fuel to the intake of the fuel into the cylinder, and it is impossible to immediately supply the required fuel amount even if the target torque is given.

In this regard, in the method of the present invention, since the fuel supply amount and the intake air amount are always controlled collectively based on the target torque, the required fuel and air can be supplied without mutual delay. As described above, it is possible to obtain a good control performance suitable for an application in which the target torque is controlled to realize good controllability of the vehicle.

Further, a sensor for detecting the amount of intake air, such as an air flow meter or a negative suction pressure sensor, which is required in the conventional method, becomes unnecessary, which is advantageous in terms of economy.

<Effects of the Invention> As described above, according to the present invention, in addition to the accelerator operation amount indicating the driver's intention to operate and the engine rotation speed, the fuel is supplied in accordance with the target torque set in consideration of the external load applied to the engine. Since the supply control and the intake air amount control are performed, it is possible to always obtain a constant optimal steering feeling in response to a change in the running state of the vehicle. Further, it is not necessary to provide a sensor for detecting the amount of intake air, and control with better responsiveness can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of one embodiment of the present invention, FIGS. 3 and 4 are flowcharts for executing the respective controls of the above embodiment, Fifth
FIG. 6 is a diagram showing a throttle valve opening degree table used in the above control, FIG. 6 is a diagram showing the same fuel injection amount table, and FIG. 7 is a control block diagram in the same control. 1 ... crank angle sensor, 2 ... accelerator opening sensor,
3 ... Stroke sensor, 5 ... Gear position sensor, 6A ...
... CPU, 6B ... ROM, 8 ... Servo drive circuit, 10 ... Throttle valve, 11 ... Throttle sensor, 12 ... Servo motor

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location F02D 41/04 330 F02D 41/04 330C 43/00 301 43/00 301H 301K (56) References JP-A-60 JP-A-175742 (JP, A) JP-A-61-83467 (JP, A) JP-A-62-225743 (JP, A) JP-A-62-26134 (JP, A) JP-A-62-110536 (JP, A) JP-A-59-10749 (JP, A)

Claims (1)

(57) [Claims] 1. A rotational speed detecting means for detecting a rotational speed of an engine, an accelerator operation amount detecting means for detecting an accelerator operation amount, a vehicle weight detecting means for detecting a vehicle weight, a reduction ratio (engine rotational speed / wheel Reduction ratio detection means for detecting a rotation speed), target torque calculation means for calculating a target torque of the engine based on the detected accelerator operation amount, engine rotation speed, vehicle weight, and reduction ratio according to the following equation: _{0 = K1 · W / m ·} a-K2 · W / m 2 · Ne where, T _0; the target torque, W; vehicle weight, m; reduction ratio, a; accelerator opening, Ne; engine speed, K1, K2; constant fuel supply amount control means for controlling the fuel supply amount to the engine according to the calculated target torque; intake air amount control to control the intake air amount to the engine according to the calculated target torque And an internal combustion engine for a vehicle, comprising: The control device.