JPS6299647A - Air-fuel ratio controller for engine - Google Patents

Abstract

PURPOSE:To aim at improvement in drivability at low speed as securing highly efficient fuel consumption, by installing a fuel injection quantity operational device calculating a fuel injection quantity on the basis of output of a desired air-fuel ratio setting device, and altering a lean limitation according to a shift position. CONSTITUTION:An injector 7, spraying fuel, is installed in a suction passage 2. A shift position detecting sensor 16 detects the shift step of a transmission. An electronic control unit 17 is provided with a device into which detection signals out of various sensors are inputted, and it sets a desired air-fuel ratio according to a shift position of the shift step, and an operational device calculating a fuel injection quantity out of the injection 7 on the basis of this set output. Thus, a lean limitation comes to be alterable according to the shift position so that improvement in drivability at low speed is well promotable.

Description

[Detailed Description of the Invention] (17 Fields of Application) The present invention enables lean-burn operation in a predetermined operating range. The present invention relates to an improvement of an air-fuel ratio control device for an engine.

(Prior Art) Conventionally, in order to improve the fuel efficiency of an engine, it is known that the air-fuel ratio is set to the stoichiometric air-fuel ratio J-rim lean side to perform so-called lean combustion (for example, (See Japanese Patent Publication No. 11fl 59-208141).

By the way, in the above-mentioned conventional device, the region (lean zone) in which lean combustion operation is possible is limited to a specific range, such as low or medium color, determined based on the engine speed and load. A target air-fuel ratio is set so that lean combustion is performed during JI operation. Here, if we try to improve the fuel ratio performance as much as possible, the standard fuel ratio is the lean combustion limit II [I! It will be set near the bribe.

However, in general, the gear position of the transmission is a low speed shift (1) - gear.
To solve this problem and improve the low-speed conversion; in order to run now, if the air-fuel ratio is set to ts < τ, it is necessary to shift the air-fuel ratio to the ridge side at low speed shift 1. . However, even if lean combustion is to be carried out, the lean limit must be changed.

However, in the past, the lean limit was only operated in a fixed lean zone based on a map determined by the engine speed and load range, and the lean limit was changed taking into account the gear shift <C1iFl. Since it is not, the lean limit W
If the target air-fuel ratio was set close to this value, the air-fuel ratio would become too lean at low speed shift positions, causing problems.

(Objective of the Invention) The present invention has been made in view of the problems of the conventional art. An object of the present invention is to provide an air-fuel ratio control device for an engine that can improve low-speed running performance by reducing the effects of 1- to 1-lux fluctuations during running at low-speed shifts while ensuring the same.

(Structure of the Invention) The present invention provides an air-fuel ratio υ control device for an engine in which combustion is performed in a predetermined operating region C air-fuel ratio leaner than the stoichiometric air-fuel ratio. A position detection means, a target air-fuel ratio setting means for setting a lean limit target air-fuel ratio based on the shift position, and based on the output of this setting means, fuel injection 1>1! The engine is equipped with a fuel injection l1i61 operating means for operating the shift lever l1i61, and is configured to change the lean limit in accordance with the shift l-position.

With this configuration, the air-fuel ratio is corrected according to the gear shift position, and the air-fuel ratio is set to the 7J"J lean side during a high-speed shift, and to a slightly richer side than this during a low-speed shift. This makes it possible to reduce the effects of torque fluctuations when driving at low speed shifts.

(Embodiment) Fig. 1 shows the configuration of an embodiment of the air-fuel ratio control device for an engine according to the present invention, in which 1 is an engine body, 2 is an intake passage communicating with a combustion chamber 3, and this intake passage 2 has an upstream From the side, there is an air cleaner 4, an air flow meter 5 that detects the amount of intake air,
Throttle valve 6 and injector 7 that injects fuel
is provided. 8 is an intake air temperature sensor that detects the intake air temperature, 9 is a thrower position sensor that detects the opening degree of the throttle valve 6, and 10 is a pressure sensor that detects the intake negative pressure in the intake manifold downstream of the throttle valve 6. ,1
1 is a water temperature sensor that detects the engine water temperature.

12 is an exhaust passage communicating with the combustion chamber 3;
The exhaust manifold that constitutes 2 has an oxygen concentration sensor (02 sensor) that detects the oxygen temperature in exhaust gas. The air-fuel ratio (A/F) signal from this air-fuel ratio sensor 13 is transmitted to the electronic controls 1 to 17 described later.
is input to perform feedback (F/B) control.

Further, as is well known, the -V three-way catalyst 14 has a maximum purification ability near the stoichiometric air-fuel ratio. 15 is the rotation speed sensor that detects the engine rotation speed, 161! - Shift position detection sensor that detects the gear position of the transmission!
There is already.

Reference numeral 17 is a means for manually inputting the detected values of the various sensors described above, and as described later, means for setting a target air-fuel ratio according to the shift position of the gear stage, and based on this set output, the fuel injection amount from the indicator I controller 7. An electronic control unit (hereinafter referred to as I:CU) equipped with an igniter 1 and an ignition means, 18 emits a high-voltage pulse for ignition, and one from the igniter 1ε3. A distributor which rotates 1 J in conjunction with the rotation of the engine crankshaft for distributing high-pressure pulses to each cylinder of the engine body 1, and 20 is a battery. 91 control equipment CU
17 will be explained together with the flow rate shown in FIGS. 2 and 3.

FIG. 2 shows a fuel injection pulse routine, in which the system is initialized in step S1 a3, and in step S2, the engine rotation speed Ne from the rotation speed sensor 1F5 is sent to the ECU"+7, and the airf[]- Intake air 1a I-D from meter 5, air-fuel ratio (A/F) from air-fuel ratio sensor 1 to 3, intake temperature from intake temperature sensor 8, popularity 1 from atmospheric pressure sensor (not shown) The throttle opening control signals from the throttle position sensor 9 are input, and then in step S3 the engine speed Nc and intake air amount 1. The basic injection of fuel is performed by the preset processing based on the input flft.
” Says BASE.

Next, in step S4, it is determined whether or not the operating state of the engine is in the lean control region Vt (lean zone), and when it is in the lean zone, the process moves to step S5, and the shift position is Detection sensor 1
A correction coefficient C8F of the shift pattern air-fuel ratio (A/F) is determined according to the shift position signal from 6. Subsequently, in step S6, various correction coefficients are calculated. That is,
Intake temperature correction coefficient C based on the intake temperature signal from the intake temperature sensor 8, IR number CP to the atmospheric pressure correction section based on the atmospheric pressure sensor signal, water temperature correction coefficient CI4 based on the water temperature signal from the water temperature sensor 4/11, from the air-fuel ratio sensor 13. Feedback (F/B) correction coefficient C18 based on the air-fuel ratio signal of
An edge correction coefficient CE that corrects F to the rich side; an acceleration correction coefficient 0AccJ3 that performs correction L during acceleration and deceleration according to the changing field of the throttle position sensor 5);
and slow down? 1lii''l] Coefficient C, learning compensation IEC when memory correction is performed by learning Supplementary 1 [Coefficient O3l'DY and invalid injection time TV are calculated.

Based on these 9 output values, in step S7, the final injection pulse T, is determined as T,=T XC+ +
BASE xc
+C+C)+As a TV? Calculate.

[FBS DY] Based on this result, a predetermined fuel injection is performed from the injector 7, and the air-fuel ratio is feedback-controlled.

Further, in step S4, when the engine operating state is not in the lean zone, the shift pattern air-fuel ratio (A/F) correction in step S5 is not performed, and the supplementary 1F coefficient CA, -1 is set in step S8. , move to step S6 tjI! Then, perform the same operation.

FIG. 3 shows the shift pattern air-fuel ratio (△/1-) correction signal routine, and shows the correction coefficient CAl- in step S5 above.
This is to set. That is, in step S11, based on the signal from the shift position detection sensor 16,
The gear V position GP is read, and then in step Sη, assuming that the correction coefficient is set stepwise from low speed shift 1 to high speed shift 4, the above detected gear position is set as shown in Table 4.
Read the corresponding coefficient OA from the table set according to the table, and use it as the shift position 1N air-fuel ratio (A/F) correction coefficient O.
A.

shall be. Here, for example, gear A7 position GP is 1.2°3.
Each correction coefficient CAF of Togi which is 4 is 077,
0.72, 0.7. Culms with a higher shift of 0.64, the coefficient is smaller, that is, the air-fuel ratio (Δ/F)
is set to shift to the lean side at 19.20 and 21.23.

In this way, the shift pattern air-fuel ratio (
Δ/F) The correction coefficient CA read out by the correction subroutine is taken into account in steps S5 and S7 of the fuel injection pulse calculation routine in FIG. 2, and the target air-fuel ratio is set according to the shift position. , therefore Schiff I-
Depending on the position, the air-fuel ratio (Δ/F) can be set to the higher side when fl is in high gear. Therefore, when operating at low speed, the air-fuel ratio (Δ/F) remains on the lean side.
is prone to misfire, and the engine torque fluctuation (roughness)
While y vy7 becomes unpopular, the present invention can reduce the occurrence of such a phenomenon.

(Effects of the Invention) As described above, according to the present invention, in the air-fuel ratio control device that shifts the air-fuel ratio to the lean side in an operating region where lean combustion is possible, Set the lean limit target air-fuel ratio, and set 7. The lean limit 9J will be changed at 1st and 6th shift position, and if the lean limit is exceeded during low-speed VY operation, it will be noticed. It is possible to reduce the influence of the engine's 1-rook fluctuation (roughness) that occurs in the engine, and therefore it is possible to improve the running performance at low speeds.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of an actual flow of the air-fuel ratio control head of the engine of the present invention, and Fig. 2 is a flowchart of the fuel injection pulse operation Q-rube for explaining the operation of the device. -G, 3rd
The figure shows a flow 11-1-0 of the Schiff pattern air-fuel ratio correction subroutine. 1... Engine body, 7... Injector, 13.
... Air fuel ratio adjustment, 16 ... Shift position detection sensor,
17...Electronic control unit (ECU).

Claims (1)

[Claims] 1. In an engine air-fuel ratio control device that causes combustion to be performed at a leaner air-fuel ratio than the stoichiometric air-fuel ratio in a predetermined operating range, the engine air-fuel ratio control device includes a shift position detection means for detecting the gear position of the transmission, and a lean limit detection means according to the shift position. It is characterized by comprising a target air-fuel ratio setting means for setting a target air-fuel ratio, and a fuel injection amount calculation means for calculating a fuel injection amount based on the output of this setting means, and changing the lean limit according to the shift position. Air-fuel ratio control device for engines.