JPH01142228A - Air-fuel ratio control device for engine - Google Patents

Abstract

PURPOSE:To prevent the dispersion of the air-fuel ratio by receiving the detection value of a cylinder inner pressure sensor at the first half of the intake stroke to determine the fuel injection quantity, performing the fuel injection at the second half of the intake stroke, and correcting the injection quantity in response to the throttle opening change quantity in the injection stroke. CONSTITUTION:During the operation of an engine, on which cylinder the cylinder inner pressure is detected is judged 12 based on the output of a crank angle sensor 8. The cylinder inner pressure in the preset period at the first half of the intake stroke is accumulated and differentiated based on the output of a cylinder inner pressure detecting means 1 to calculate 13 the cylinder inner pressure change speed. The corresponding intake air quantity is determined 15 in reference to a map 14 based on the engine rotating speed determined by a setting means 20 and the cylinder inner pressure change speed, and the fuel injection quantity is determined 16 based on this intake air quantity. The presence of the depression of an accelerator and the opening change quantity are calculated 17 from the output of a throttle opening sensor 10a, and the fuel injection quantity is corrected 19 according to the injection quantity correction value determined 18 based on the change quantity.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an air-fuel ratio control device for an engine.

[Conventional technology]

This type of air-fuel ratio control II device measures air by installing an air flow meter (flapper type or hot wire type) upstream of the intake system, or by installing a pressure sensor in the intake pipe, and then using the measured value to measure the air flow. It is known that Shino calculates the average air flow rate of the cylinders and determines the fuel injection R for the fuel 1 injector.The problem with this method is that it cannot deal with variations in each cylinder, so the error , the amount of air actually sucked into the cylinder is not directly measured, so there is a large response delay, and the transient characteristics under operating conditions are poor. like,
A system has been proposed that measures the cylinder pressure and injects fuel. Compared to the above-mentioned method, this method improves cylinder variation and responsiveness.

[Problem to be solved by the invention 1] However, even with this method, the fuel injection amount corresponding to the air amount measured in H1 in a cycle is not reflected in the length of the cycle, but is used in the next cycle. It essentially had an element of delayed response. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an engine air-fuel ratio control device that can eliminate variations and fluctuations in the air-fuel ratio between each cylinder and each cycle of the engine, and can perform air-fuel ratio control without response delay. [Means for Solving the Problems] Therefore, the present invention includes a cylinder pressure sensor that detects the pressure inside the engine cylinder, and controls the fuel injection valve corresponding to each cylinder based on the detected value of the cylinder pressure sensor. When setting the fuel injection m, the detection value of the cylinder pressure sensor is taken in.
means for determining the intake air amount for the cycle in the first half of the intake stroke in the relevant cylinder; means for setting the injection amount for performing fuel injection in the second half of the intake stroke based on the determination result; The system is equipped with means for detecting changes in the throttle opening degree during the process up to the end of fuel injection, and means for correcting the injection rA suspension in accordance with the amount of change when there is a change in the throttle opening degree. [Effect 1] Therefore, since the detected value of the cylinder pressure sensor is taken in early, the fuel injection m determined as a result is adopted for fuel injection in the latter half of the intake stroke in that cycle, so there is no response delay at all. There is no. Further, even if the throttle is operated during the process from the start of intake to fuel injection, it can be corrected. Moreover, the advantages of using the in-cylinder pressure sensor are utilized as is, and there is no variation or fluctuation in the air-fuel ratio for each cylinder or each cycle of the engine. [Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings. In the figure, the symbol @1 is an engine, and each cylinder 2a, 2b, . . . has an in-cylinder pressure sensor 3.
A, 3b... are arranged, and a fuel injection valve 5 is provided in the intake manifold 4a, 4b... for each cylinder.
a, 5b... are provided. Above cylinder pressure sensor D
3a. 3b... supplies the detected signals to the control unit 6, and the control unit 6 uses the means described in detail below to control the fuel injection valves 5a, 5a, and 3b corresponding to each cylinder.
A drive signal for 5b... is output from the fuel injection drive means 7. In the figure, numeral 8 is a crank angle sensor, 9 is an exhaust pipe, 10 is a throttle valve provided in the intake system, and 10a is a throttle opening sensor. The controller 1 to the roll unit 6 have a cylinder pressure sensor 3a,
Cylinder pressure detection means 11 receives signals from the crank angle sensor 8, cylinder discrimination means 12 determines in which cylinder the cylinder pressure is to be detected based on the signal from the crank angle sensor 8, and cylinder discrimination means 12 determines the cylinder pressure for each cylinder based on the signal from the crank angle sensor 8. During a predetermined 191 period in the first half of the intake stroke, the cylinder pressure change rate calculation means 13 calculates the cylinder pressure change rate by differentiating the output signal of the cylinder pressure detection means 11, and the engine rotation speed is determined by the crank angle sensor. Setting means 20. A map 14 in which the amount of intake air corresponding to the rate of change in cylinder pressure is set in advance for each engine speed, and the rate of change in cylinder pressure calculation means 13
and an intake air m setting means 15 which sets the intake air 1 from the map 14 based on the output value of the engine speed setting means 20, and a fuel injection m determination which determines the fuel injection 1) corresponding to the intake air amount. means 16, throttle opening change calculation means 17 for determining the throttle opening by a differential value of the change in the output value of the sensor 10a, injection type correction value setting means 18 for setting an injection layer correction value according to the differential value, and the above correction. Fuel injection m determining means 19 for correcting fuel injection 11) lfa by the value
Equipped with: In this embodiment, the predetermined period in the in-cylinder pressure change rate calculation means 13 may be, for example, about ATD 030 to 50'' from the overlap TDC. In such a configuration, first, step 5101 Based on the signal from the crank angle sensor, the cylinder discriminating means 12
to determine which cylinder's in-cylinder pressure is to be detected. Next, in step 5102, the output signal from the in-cylinder pressure detection means 11 is received by the in-cylinder pressure change rate calculation means 13, and the instantaneous in-cylinder pressure within a predetermined period is accumulated, and this is differentiated. Obtain the rate of pressure change. Next, in step 8103, the engine speed setting means 20 sets the engine speed, and in step 104, the intake air setting means 15 extracts the corresponding intake air amount from the map 14. Next step 51
At step 05, the fuel injection m determining means 16 determines the fuel injection amount corresponding to the relevant cylinder. In step 8106, the throttle opening change calculation means 17 differentiates the signal of the throttle opening sensor 10a in the process from TDC of the intake stroke indicated by the crank angle sensor 8 to fuel injection,
Determine the presence or absence of depression and the amount of change in opening. If there is no depression, the process moves to step $107, and the drive means 7 is controlled in step 8108 by using the fuel injection amount determined by the fuel injection amount determining means 16 as the basic injection amount,
Operate the applicable fuel injection valve. If, in step 5106, the throttle opening moves to the depression side (that is, the opening change changes to the + side), the injection amount correction fi! The setting means 18 obtains a correction value, and in step 5109, the fuel injection m correction means 19
Accordingly, a correction value corresponding to the throttle opening is added to the basic injection amount to determine a corrected fuel injection 04ffi, and the driving means 7 is thereby controlled in step 8108. Further, if the throttle opening moves to the return side (that is, the opening changes to one side) in step 8106, a correction value is determined by the injection m correction value setting means 18, and in step $110, the correction value is determined by the fuel injection m correction value setting means 19. Accordingly, for the above basic fuel injection m,
A correction value corresponding to the throttle opening is added to determine the corrected fuel injection amount, and thereby, in step 8108, the drive means 7
control. In this way, in the first half of the intake stroke, the signals from the cylinder pressure sensors 3a, 3b, etc. are calculated to determine the amount of intake air, and in the second half of the intake stroke, fuel is injected with the corresponding fuel injection amount, so the same cycle This means that everything from detection to fuel injection can be performed within the system, so there is no response delay. In the above embodiment, the in-cylinder pressure change rate was determined using the in-cylinder pressure change rate calculation means 13, and the intake air m was determined from the map 14 in accordance with that value and the engine speed. At corner B, the amount of intake air may be determined using the map 14 from the value of the internal pressure sensor and the engine speed at that time. This is because it is considered that the absolute pressure at the predetermined crank angle B<mI internal pressure sensor value) corresponds to the load. For this purpose, as shown in FIG. 4, it is necessary to use a time period B that is slower than when determining the rate of change in cylinder pressure between TDC and the required crank angle Δ. This is because it is necessary to wait until the cylinder pressure is saturated. Effects of the Invention The present invention is as described in detail below. Since the detected value of the cylinder pressure sensor is taken in the first half of the intake stroke, the fuel injection [1] determined as a result is Since it is used for fuel injection in the latter half of the intake stroke, there is no response delay at all. Furthermore, even if the throttle is operated during the process from the start of intake to fuel injection, it can be corrected. Moreover, the advantages of using the cylinder pressure sensor are still utilized, and variations and fluctuations in the air-fuel ratio between each cylinder and each cycle of the engine are eliminated.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of a control unit, Fig. 3 is a control approach 1P, and Fig. 4 is a diagram showing a change in cylinder pressure. This is a graph showing the situation. 1...Engine, 2a, 2b...Cylinder, 3a,
3b~... Cylinder pressure sensor, 4a, 4b~... Intake manifold, 5a, 5b~... Fuel injection valve, 6...
- Control unit, 7... fuel injection drive means,
8... Crank angle sensor, 11... Cylinder pressure detection means, 12... Cylinder discrimination means, 13... Cylinder pressure change rate calculation means, 14... Map, 15... Intake air severity Setting means, 16...Fuel injection determining means, 17...
Throttle opening degree change calculation means, 18... Injection rJ4 suspension correction value setting means, 19... Fuel injection amount correction means. Patent Applicant: Fuji Heavy Industries Co., Ltd. Agent, Patent Attorney: Makoto Kobashi, Patent Attorney: Susumu Murai, Procedural Amendment (Method), 5゜March 18, 1988, Commissioner of the Japan Patent Office, No. 1)
, incident display
6゛1986 Patent Application No. 301770
1. Name of the invention Engine air-fuel ratio control device 7
゜3. Relationship with the case of the person making the amendment Patent applicant ~ Date of amendment order (shipment date) February 23, 1985 Part of the 7 pages subject to amendment (Figures 2 and 3) Amendment Contents 1III As per the paper

Claims (1)

[Claims] The engine is equipped with a cylinder pressure sensor that detects the pressure in the cylinder, and sets the fuel injection amount of the fuel injection valve corresponding to each cylinder based on the detection value of the cylinder pressure sensor, a means for determining the intake air amount for the cycle by performing intake in the first half of the intake stroke in the relevant cylinder; a means for setting an injection amount for injecting fuel in the second half of the intake stroke based on the determination result; A means for detecting changes in throttle opening during the process from the beginning of fuel injection to the end of fuel injection, and when there is a change in throttle opening,
An air-fuel ratio control device for an engine, comprising means for correcting an injection amount according to the amount of change.