JPS6321817B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel control device for an internal combustion engine, and more specifically, it compares an output signal commanded by a driver with a detected output signal, and controls the engine according to the difference. , relates to a fuel control system for a vehicle having a high power-to-weight ratio.

Although the invention will be described with respect to a diesel engine, it is clear that the basic principles of the invention are also applicable to spark ignition engines. In conventional diesel engines with electronic fuel controls with electronic speed governors, the controller typically operates as a speed controller, but this type of control is also used for other purposes. It can be completely covered by the equipment. However, compared to trucks and the like, in a passenger car having a high power-to-weight ratio, a normal speed control device results in a somewhat different vehicle response or maneuverability. This is because even a slight change in the input by the driver causes a large change in the torque output.

In addition, in conventional discharge ignition engines, before operating the engine with extremely lean fuel to improve fuel efficiency and restrictions due to strict emission control,
The engine was running on fuel-rich conditions. In this mode of operation, the torque output of the engine is proportional to the manifold pressure due to air flowing past the throttle plate and into the cylinders. In this case, the throttle plate acts as a means of restricting air flow into the engine. When the pressure developed in any orifice, such as a throttle plate orifice, exceeds a certain ratio of the total input pressure, the velocity of air molecules passing through the orifice reaches the speed of sound. Such a flow is called a sonic flow, a critical flow, or a Chiyok flow. Under these conditions, the amount of air passing through the orifice is independent of the pressure downstream of the orifice and is influenced solely by the upstream pressure and orifice area.

When a discharge ignition engine like this is operated with the throttle wide open (partial load condition), the engine is basically operating at a constant air-fuel ratio, and the output power depends on the air flow. is directly related to. Since this airflow is only related to the throttle area under sonic flow conditions, the engine output power is directly related to the throttle area and, by extension, to the rotation of the throttle by the driver.

In this way, the operating characteristic in which the movement of the throttle plate is directly related to the output power is perceived by many drivers as having good maneuverability, and it also improves the responsiveness of the engine operation in response to changes in the throttle. This means that it is in good condition.

The present invention provides a device that realizes power control with good maneuverability over a wide range of throttle inputs. The following description of the present invention will be made with reference to the case where it is applied to fuel control of a diesel engine, and the present invention improves the throttle response of the engine and allows the driver to control the engine without sacrificing the emission characteristics or operating characteristics. It will be seen that a satisfactory engine is provided.

Accordingly, a first object of the present invention is to improve the handling characteristics of an internal combustion engine vehicle.

Other objects, features, and advantages of the invention will become apparent from the accompanying drawings and detailed description of the invention.

In a diesel engine that is simply operating stoichiometrically lean, typically very lean,
The torque output of an engine is empirically related to the amount of fuel injected per cycle. Of course, power can be obtained from speed and torque as shown in the following equation.

Power = K (torque x rpm) Here, K is a proportionality constant.

Therefore, in the device of the present invention, the driver's input can be considered to be the required value of the power level. Then, through calculations in the electronic control unit, the amount of fuel discharged and the engine speed are detected, and by obtaining a signal of the amount of fuel per revolution of the engine, the effective power actually produced is calculated. Conversely, this signal is used as a signal indicating the effective power actually generated. This calculated power signal is compared with a command power signal from the driver's input to generate an error signal. This error signal drives the device to minimize the error, thereby maintaining the commanded power level. Clearly, there is an upper limit to engine power output at any speed. This upper limit is recognized by the control unit, the power limit is generally proportional to speed, and the amount of fuel to the engine is limited accordingly to the amount of fuel used by the engine. Smoke characteristics, stress levels, and other parameters are also considered in the control unit design. When an error signal occurs, the correction process used in the apparatus of the present invention operates the fuel control system to generate appropriate pulses for the fuel injectors to ensure that the power level commanded by the operator is achieved by the engine. Make it.

This process can also be applied to spark ignition engines with some computational correction by varying the air/fuel ratio. However, as long as the engine is stoichiometrically lean, torque output is directly related to fuel input per cycle. However, if the air/fuel ratio changes or if the engine is stoichiometrically rich and has used up essentially all of the cylinder's available oxygen, the above corrections may be due to changes in manifold concentrations such as manifold pressure and temperature. It needs to be done based on parameters. Therefore, when the throttle is moved, the power level immediately rises to a new power point determined by the throttle area at the new throttle position, where the power remains, and the engine speed follows. Additionally, engine performance causes torque to drop across the road load curve of the torque vs. engine speed graph in power control conditions.

It is believed that an engine with this transient response characteristic provides excellent maneuverability. However, for emissions control and fuel economy purposes, it is desirable to eliminate the sharp peaks that occur when transitioning from one power level to another due to initial throttle changes. Also, when a speed close to the demand expressed by the new power level is reached, a slight slope of the engine torque vs. speed characteristic indicates good road speed stability.

A driver command signal representing the commanded power is input from input conductor 10 in the figure. The command signal on lead 10 represents the power level requested by the driver as commanded by the position of the throttle plate. This appropriately standardized command signal is sent to comparator 1.
2 is fed to one input. A further input of this comparator 12 receives the amount of fuel per engine revolution signal generated via an input line 14. The signal on lead 14 represents the power produced by the engine. This will be explained in detail later.
If there is a difference between the power demanded by the driver, represented by the signal on lead 10, and the power produced by the engine, represented by the signal on lead 14, the difference between the two signals will be An error signal representative of the difference in power is provided on conductor 16.

The signal on lead 16 is applied to an up-down counter 20 having a set count, said signal incrementing or decrementing counter 20 depending on the polarity of the signal on lead 16. The output of the counter 20 is passed through a limiter 24 to a pulse generator 2.
2. Limiter 24 is used to limit the signal to a maximum value, and its output signal is sent to pulse generator 22. The fuel pulse signal is delivered to the injector by output amplifier 24 and output lead 26 of pulse generator 22. The output signal sent to the injector solenoid connected to lead 26 is controlled by a trigger pulse generated by an electronic control unit and sent to input lead 28.

The feedback circuit that generates the actual power signal on conductor 14 includes a multiplier 30 having multiple inputs.
have. One of the inputs is the fuel pulse width signal on lead 32. This signal is a pulse width signal sent by a pulse generator, the pulse duration of which represents the amount of fuel in each fuel pulse. This signal is multiplied with the engine speed signal sent to the other input of multiplier 30 by lead 36 connected to the engine speed sensor. The output of multiplier 30 thus represents the amount of fuel delivered to the engine. As is clear from the above explanation,
This amount of fuel is directly related to the power produced by the engine.

The limiter 24 includes an air/fuel limit table storage device 4.
An input from 0 is provided via conductor 44. The limit table storage device 40 receives the engine speed signal from the conductor 36 and the mass air concentration signal from the mass air concentration sensor connected to the input conductor 42. Thus, the engine speed signal and the mass air concentration signal combine to provide an output signal on lead 44 that is indicative of the maximum pulse width that pulse generator 22 will generate. The limiter 24 is an up-down counter 20
serves to limit the output signal to the maximum value to which the output signal is incremented.

Suppose that the driver changes the position of the throttle during driving, for example, by increasing the throttle angle. The input signal on conductor 10 changes and the input signal on conductor 14
Since the signal represents the previous power setting, comparator 12 naturally generates an error signal. This error signal changes the count of counter 20 and increases the pulse width of the output signal from amplifier 34. This is done without exceeding the limitations of table storage 40.

As is clear from the above description, the fuel control device controls the fuel sent to the engine based on the requested power from the engine. Although the signal obtained by multiplying the fuel pulse width by the engine speed does not accurately represent engine power, it is clearly linearly related to engine power. Multiplication of the two signals can serve the purpose of a power control configuration to obtain a desired level of maneuverability. The circuit can be modified without departing from the spirit of the invention by refining the control configuration or changing the way data signals are processed. For example, in a feedback circuit, a delay mechanism may be provided between pulse generator 22 and multiplier 30 to maintain stability of the device. This device is also modified to include an air-fuel ratio limiter in the driver input command signal circuit to provide a driver command power signal representing a percentage of the maximum or limit fuel amount supplied to the engine per cycle. It's good as well.

[Brief explanation of the drawing]

The drawing is a block diagram of the fuel control device of the present invention. 12... Comparator, 20... Up-down counter, 22... Pulse generator, 24... Limiter, 30...
Multiplier, 34...Power amplifier, 40...Air-fuel ratio limit table storage device.

Claims (1)

Claims: 1. comprising a device for generating a driver power command signal, a device 32 for providing a signal representing the amount of fuel to be delivered to the engine, and a device 36 for providing a signal representing the engine speed; devices 32, 36 for detecting engine parameters representative of the power delivered by the engine; and device 30 for multiplying the quantity of fuel by the engine speed signal to provide a signal representative of the power delivered from the engine. , a device 12 for comparing the driver power command signal and the signal representative of the power and generating an error signal representative of the difference therebetween; and a device 12 connected to receive the error signal from the comparison device 12 and for generating the error signal. a device 20 for varying the amount of fuel sent to the engine so as to reduce the amount of fuel to zero; Fuel control device for. 2. In the device according to claim 1,
A fuel control device characterized in that the engine is a pulse type fuel injection engine, and the device 20 for changing the amount of fuel sent to the engine changes the width of the fuel pulse. 3, a device for generating a driver power command signal, a device 32 for providing a signal representing the amount of fuel to be delivered to the engine, and a device 36 for providing a signal representing the engine speed; a device 32, 36 for detecting engine parameters representative of the engine; a device 30 for multiplying the fuel quantity and engine speed signals to provide a signal representative of the power delivered by the engine; and a driver power command signal. an engine connected to receive the error signal from the comparator 12 and to zero the error signal; according to the power demanded by the driver from the engine, characterized in that it consists of a device 20 for varying the amount of fuel sent to the engine and devices 24, 40 for limiting the amount of fuel sent to the engine to a maximum value. Therefore, a fuel control device for controlling the amount of fuel sent to the internal combustion engine.