JPH01313636A - Controller for internal combustion engine for vehicle - Google Patents

Abstract

PURPOSE:To obtain the superior constant steering feeling at all times in correspondence with the change of the traveling state of a vehicle by controlling the fuel feed quantity and the intake air quantity according to the aimed torque set in consideration of an outside load applied onto an engine. CONSTITUTION:A crank angle sensor 1 detects the engine revolution speed and an accelerator opening degree sensor 2 detects the operation quantity of an accelerator pedal. Further, an outside load applied onto the output shaft of the engine is detected by a stroke sensor 3 for detecting the sinking quantity of a suspension, and a gear positions sensor 5 for detecting the gear position of a transmission 4. A CPU 6A reads out the fuel injection quantity necessary for outputting an aimed torque which is calculated on the basis of each detection signal, from a table 6B1, and fuel feed control is carried out by outputting the fuel injection pulses having the corresponding pulse width into an injector 7. Similarly, the aimed throttle valve opening degree for providing the necessary intake air quantity is read out from a table 6B2, and outputted into a servodriving circuit 8, and the intake air quantity is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control device for appropriately changing the characteristics of a vehicle internal combustion engine in accordance with the driving condition of the vehicle to always obtain good driving performance.

<Prior Art> Conventional control devices for internal combustion engines for vehicles include the following.

As a method of making the torque characteristics and output characteristics of the engine in response to the accelerator operation desirable characteristics for vehicle drivability, for example, as shown in Japanese Patent Application Laid-open No. 60-192843, it is possible to There is a device that determines a throttle valve opening and drives the throttle valve to match the set opening.

Furthermore, the system disclosed in Japanese Utility Model Application No. 62-193151 is designed to control the governor of a diesel engine in a similar manner.

In addition, as an example of switching the control mode of the engine output adjustment means according to the driving condition of the vehicle so that the driver can obtain the desired drivability under various driving conditions, for example, There is one shown in No. 63-25355.

<Problems to be Solved by the Invention> However, in such conventional vehicle internal combustion engine control devices, engine torque, which is a physical quantity that directly affects vehicle control, is not used as a reference quantity for control; Since the configuration uses the throttle valve opening, which is an indirect control variable, as a reference variable for control, the engine's It is not possible to freely adapt the torque characteristics and maintain a constant steering feel.

Furthermore, with conventional fuel supply systems that supply fuel by detecting changes in the amount of intake air, it is not possible to instantaneously generate the required torque.

The present invention has been made in view of these conventional problems.The present invention solves the above problems by controlling the engine torque to a target value in consideration of the engine output characteristics that change depending on the external load applied to the engine. An object of the present invention is to provide a control device for a vehicle internal combustion engine that solves the problem.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention comprises: a rotational speed detection means for detecting the rotational speed of an engine; an accelerator operation amount detection means for detecting an accelerator operation amount; external load detection means for detecting an external load applied to the output shaft of the engine; target torque calculation means for calculating a target torque of the engine based on the detected accelerator operation amount, engine rotational speed, and external load; the fuel supply amount control means for controlling the amount of fuel supplied to the engine according to the calculated target torque, and the intake air amount control means for controlling the amount of intake air to the engine according to the similarly calculated target torque. composition.

<Function> 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. Detect.

The target torque calculation means calculates a target torque of the engine based on the detected accelerator operation amount, engine rotation 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 similarly controls the intake air amount according to the target torque.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing the configuration of an embodiment, a crank angle sensor 1 is used as a rotational speed detection means for detecting the crank angle and rotational speed of an engine (not shown), and the operation amount (depression amount) of an accelerator pedal is detected by the output voltage of a potentiometer. An accelerator opening sensor 2 serves as an accelerator operation amount detection means, and a stroke sensor 3 detects the amount of depression of the suspension of the vehicle based on the output voltage of a potentiometer.
, a gear position sensor 5 that detects the gear position (shift position) of the transmission 4 is provided, and detection signals from these sensors are input to the CPU 6A of the microcomputer.

Here, the stroke sensor 3 and the gear position sensor 5
Since the external load applied to the output shaft of the engine can be determined by these detection signals, the external load detection means constitutes an external load detection means.

The CPU 6A calculates a target torque based on each of the detection signals, reads out the fuel injection amount (supply amount) necessary for outputting the target torque from the fuel injection amount table 6B, and calculates a fuel injection amount corresponding to the fuel injection amount (supply amount) necessary to output the target torque. Fuel supply control is performed by outputting a fuel injection pulse having a pulse width to an injector provided in an intake passage of an engine. Similarly, the target throttle valve opening that provides the amount of intake air required to output the target torque is read from the throttle valve opening table 6Bz and output to the servo drive circuit 8 to control the amount of intake air.

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

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

In the fuel injection amount table 6B, fuel injection amount data is stored in the ROM 6B so that the fuel injection amount necessary to generate the target torque can be read out if the target torque and engine speed are given moment by moment. , Similarly, the throttle valve opening degree table 68z also stores data on the amount of intake air in the ROM 6B so that the amount of intake air required to generate the target torque can be read by giving the target torque and engine speed from time to time.
is stored in

The servo drive circuit 8 operates based on the actual throttle valve opening θ detected by a throttle sensor 11 that detects the opening of a throttle valve IO installed in the intake passage 9 of the engine, and the target throttle valve opening input from the CPU 6A. degree θ. The servo motor 12 connected to the throttle valve 10 is driven in the forward and reverse directions according to the deviation from the target value, thereby causing the opening degree of the throttle valve 10 to follow the target value.

Next, engine control by the CPU 6A will be explained according to the flowcharts shown in FIGS. 3 and 4.

FIG. 3 shows a routine for calculating the target torque, fuel injection amount, and target throttle valve opening, and is executed at a constant period, for example, every Ioms.

At P, the accelerator opening (operation amount) a is read from the accelerator opening sensor 2.

At Pt, the engine rotation speed N is determined based on the crank angle signal from the crank angle sensor 1. Calculate.

At P, the target torque T0 is calculated according to the following equation.

TO=J Ha kg HNa + H+
(1) kl and kt are parameters that determine the characteristics of the engine's output torque, kl is the proportional coefficient of the accelerator opening to the engine's output torque + kt is the proportional coefficient of the engine rotation speed to the output torque, and is determined by the routine described below. It is set according to the external load applied to the output shaft of the engine, which is detected based on the weight of the vehicle and the gear ratio of the transmission.

P4 is the engine rotational speed N calculated by Pt.

The basic injection pulse width Tp of fuel is read from the fuel injection amount table 6B+ based on the target torque T0 calculated using Ps. Here, the fuel injection amount table has target torque T0 and engine rotation speed N as shown in FIG. The data of the basic injection pulse width T is read out from the data, and this data is determined from the performance of the engine installed in the vehicle.

In step P, the basic injection pulse width Tp obtained in step P4 is subjected to various corrections determined according to the operating state of the engine to calculate the fuel injection pulse width T1.

Here, the correction added to the basic injection pulse width TP is a known one, such as an increase according to the cooling water temperature, an increase at the time of starting, or a feedback correction of the air-fuel ratio based on detection of the oxygen concentration in the exhaust gas.

P6 is the engine rotation speed N calculated in P2.

Based on the target torque T6 calculated by P and P, the target throttle valve opening θ is determined from the throttle valve opening table 6B.

Read out.

As shown in FIG. 5, the throttle valve opening table 6B calculates the target throttle valve opening θ from the target torque T0 and the engine rotational speed N. This data is determined from the unique performance of the engine installed in the vehicle.

P, then the fuel injection pulse width T1 calculated by Ps is CP
Set it to the output port of U6A.

As a result, a fuel injection pulse having a pulse width of T1 is output to the injector 7 at a predetermined timing triggered by the crank angle signal from the crank angle sensor 1, and an amount of fuel corresponding to T is injected and supplied. .

At P@, the target throttle valve opening degree θ0 calculated by Pb is output to the servo drive circuit 8. As a result, the throttle valve 10 is driven by the servo motor 12 to reach the target throttle valve opening θ. feedback control to match.

FIG. 4 shows a routine for setting the output torque characteristic of the engine used for calculating P in FIG. This routine does not need to be constantly calculated at high speed like the fuel supply control and intake air amount control routines shown in Figure 3, but can be executed every gear shift or as a background job on the microcomputer to eliminate wasted calculation time. ing.

At Pl+, the gear position of the transmission 4 is read.

P1□~PI3 determine the gear position, and PI4~P
At step 16, the first gear ratio data MI, the second gear ratio data Mt, and the third gear ratio data M stored in the ROM 6B are read out, and the gear ratio of the current shift position is stored in the register m.

At Pl, the vehicle weight W is calculated from the suspension depression amount detected by the stroke sensor 3 according to the following equation.

W=W, +Il/k...(2) Here, Wo is the weight of only the vehicle body which is known in advance, 2 is the amount of suspension depression caused by the load of passengers and cargo, and is the suspension spring. It is a constant.

1 is calculated as a proportional coefficient that sets the characteristic of accelerator opening versus output torque in pHl using the following equation. ′, =, −
W/m ・ ・ ・(3) PI? Now, 2 is calculated as the proportional coefficient that sets the characteristic of engine rotational speed versus output torque using the following equation.

k z −Kg ・w/m” H+ ” (4) Here, m is the gear ratio (reduction ratio) of the transmission, and 2 is the best vehicle handling feeling determined in advance through experiments etc. is a constant.

Next, the operation of this embodiment will be explained based on FIG. 7.

FIG. 7 shows a model of vehicle motion, and is the simplest representation, omitting the power loss of the engine and drive system. In this model, the relationship between the acceleration α of the vehicle body when the accelerator opening degree a is changed is shown by the following formula, where R is the tire effective radius and W is the vehicle weight.

D is running resistance and S is Laplace operator.

The first term on the right side of equation (5) indicates the responsiveness of the vehicle body acceleration α to the accelerator opening a, and the second term indicates the responsiveness of the vehicle body acceleration α to the running resistance. It determines the feeling.

Gl = kl ・m/R-g/W ... (6) Gz
= to!・m”/R”-g/W・-(7)
G*=g/W...(8) Here, g is the gravitational acceleration.

As shown in the conventional example, when the ratio of the change in the actual throttle valve opening to the accelerator opening is changed, q in equation (6) changes, and for example, when q increases, the gain G increases and the accelerator opening changes. The change in acceleration α increases with respect to the change in degree a, resulting in a powerful steering sensation.

Furthermore, if G2 is large, a differential effect, that is, an effect that amplifies fluctuations occurs, resulting in poor maneuverability. In relation to 02 in equation (7), 2 is the slope ta of the engine torque curve as shown in Figure 7.
In the method of changing the throttle valve opening according only to the accelerator opening, 2 takes a characteristic value unique to the engine and cannot be changed arbitrarily.

In the system of the present invention, the value of 2 can be freely set by the method of calculating the target torque of the engine based on the accelerator opening degree and the engine rotation speed.

The gains G+ and Gt, which determine the handling feeling of the vehicle, have values that can provide the best feeling, and can be experimentally matched to the engine characteristics using variable factors such as +, kg, and gear ratio m.

However, as in the conventional example, unless there is a means to change l according to the external load applied to the engine determined by the vehicle weight W and the gear ratio m, even if matching is possible at a certain gear ratio, the gear The best G when you change...
G, the feeling worsens as it deviates from the range. For example, when the vehicle is in a low gear (m is large), 02 increases in proportion to the square of m, as shown in equation (7), which often results in jerky and poor maneuverability. Similarly, the vehicle weight W is also G,
.

It will affect G2.

Now, the best values kto, kt for gear ratio mo, vehicle weight W0, +, kt. Assuming that is obtained experimentally, the following relationship holds true.

Gl = kIo・mo /R' g/Wo...(
9) Gz = kzo ・me”/R” ・g/W
o ” QO) When the gear ratio m and the vehicle weight i1W change, in equations (6) and (7), kI = +o ・me /Wo ・W/mtx k,
・W/m...(10k z = k zo ・
mo”/We ・W/ m”=2 −W/m”
...If we set the values of , , and according to m and W as Q7J, we get
The gains G, ,G, can always be set to the best values shown in equations (9) and 00.

In this embodiment, the target throttle valve opening degree θ is used as a means for controlling the intake air amount according to the target torque. is output to the servo drive circuit 8, but other methods such as the target throttle valve opening θ can be used. It is also possible to output suction negative pressure according to the target value as a target value and operate a servo mechanism so that the suction negative pressure reaches the target value.

In addition to the above effects, this embodiment also has the following effects.

The fuel supply control method is to calculate the amount of air taken into the cylinder as a load equivalent value based on the intake air flow rate, suction negative pressure, and engine rotation speed, and supply the required amount of fuel in proportion to the cylinder intake air amount. is commonly done.

However, in this method, there is a delay in the detection of the sensor and a transportation delay between when the fuel is injected and when it is sucked into the cylinder, so even if the target torque is applied, the required amount of fuel cannot be immediately supplied. is impossible.

In this regard, in the method of the present invention, the fuel supply amount and intake air amount are always controlled collectively based on the target torque.
Necessary fuel and air can be supplied without mutual delay, and as described above, good control performance suitable for controlling target torque to achieve good vehicle maneuverability can be obtained.

Furthermore, it is advantageous from an economic point of view because it eliminates the need for a sensor for detecting the amount of intake air, such as an air flow meter or a negative intake pressure sensor, which was required in the conventional system.

<Effects of the Invention> As explained above, according to the present invention, the fuel is controlled according to the target torque set in consideration of the external load applied to the engine, in addition to the accelerator operation amount and engine rotation speed that indicate the driver's driving intention. Since the system is configured to perform supply control and intake air amount control, it is possible to always obtain a constant and optimal driving feeling in response to changes in vehicle driving conditions, and there is no need to provide a sensor to detect the amount of intake air. This allows for control with better responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, FIGS. 3 and 4 are flowcharts for executing each control of the above embodiment, Fifth
This figure is a diagram showing a throttle valve opening table used for the above control, FIG. 6 is a diagram showing a fuel injection amount table, and FIG. 7 is a control block diagram for the same control. 1... Crank angle sensor 2... Accelerator opening sensor 3... Stroke sensor 5... Gear position sensor 6A... CPU 6B... ROM
B... Servo drive circuit 10... Throttle valve 11... Throttle sensor 12... Servo motor patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima Figure 2, 6m, Figure 3 Figure 4 To(kc]m) To(kgm) Procedural amendments issued by the Patent Office Commissioner Yoshi on September 7, 1988 1) Takeshi Moon 1, Indication of the case 1988 Patent Application No. 144797 2, Invention Name of Control Device for Internal Combustion Engines for Vehicles 3, Person Who Makes Amendment Case Related Patent Applicant Address 2 Takaracho, Kanayō Ward, Yokohama City, Kanagawa Prefecture Name (
399) Nissan Motor Co., Ltd. Representative: Yutaka Kume 4, Agent address: Daisan Mori Building 6, 1-4-10 Nishi-Shinbashi, Minato-ku, Tokyo, Contents of amendment: Figure 7 of the drawing has been amended as per the attached amended drawing. do. 7. Attached document catalog correction drawings At least 1 letter.

Claims (1)

[Scope of Claims] Rotational speed detection means for detecting the rotational speed of the engine; accelerator operation amount detection means for detecting the accelerator operation amount; external load detection means for detecting an external load applied to the output shaft of the engine; a target torque calculation means that calculates a target torque of the engine based on the detected accelerator operation amount, engine rotational speed, and external load; and a fuel supply that controls the amount of fuel supplied to the engine according to the calculated target torque. 1. A control device for an internal combustion engine for a vehicle, comprising: a quantity control means; and an intake air quantity control means for controlling an intake air quantity to the engine in accordance with a similarly calculated target torque.