JPH03286173A - Evaporated fuel controller for engine - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the traveling performance by installing an evoporated fuel feed restricting means for reducing the feed of the evaporated fuel when a high load region detecting means detects the high load region and the feedback correction quantity of an air-fuel ratio control means becomes over a prescribed value set on the rich side. CONSTITUTION:When the engine state is in a purge region and the purge condition is satisfied, a control unit 21 judges if the feedback correction quantity (CFB) which is obtained by integration-calculating the signal supplied from an air-fuel ratio sensor 14 is over a prescribed value set on the rich side, i.e., CFB>alpha. Accordingly, the air-fuel ratio is in a lean side, and the evaporated gas in a canister is zero, and air is supplied. In case of CFB>alpha, purge is not carried out, and return to start is carried out, in a feedback delay zone. The feedback delay zone is the zone for temporarily delaying the high load increased quantity of fuel during the transition from the feedback zone to the high load zone, and feedback control is continued in this zone.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an evaporated fuel control device for an engine that supplies evaporated fuel from a fuel tank to an intake passage.

(Prior art) As an evaporative fuel control device for an engine,
As disclosed in Publication No. 721, evaporative gas (evaporated fuel) generated in the fuel tank is first adsorbed in the canister, and when the throttle valve reaches a certain opening degree or more during engine operation, the evaporative gas (evaporative fuel) is released into the intake passage. What is supplied is known.

(Problem to be Solved by the Invention) This type of engine evaporative fuel control device supplies only air to the engine intake system when the engine is operated for a long time and the evaporative fuel in the canister is desorbed. It turns out. Furthermore, since this air is supplied downstream of the throttle valve, the air-fuel ratio of the air-fuel mixture supplied to the engine is changed to IJ-, which impedes stable operation of the engine.

Incidentally, recently, air-fuel ratio feedback control devices are commonly used which detect the air-fuel ratio of the air-fuel mixture supplied to the engine using an exhaust sensor and feedback-control the air-fuel ratio to a target value. Although this air-fuel ratio feedback control device can compensate for the lean air-fuel ratio to some extent, these air-fuel ratio feedback control devices normally limit the air-fuel ratio correction range in consideration of failure of exhaust sensors, etc. When the lean air-fuel ratio by the fuel control device exceeds the air-fuel ratio correction range, compensation becomes difficult.

In particular, since the high load region within the air-fuel ratio feedback region is close to the output region, the driving performance deteriorates and at the same time, the catalyst temperature rises excessively.

Therefore, when the feedback correction amount of the air-fuel ratio feedback control device becomes equal to or higher than a predetermined value, it is conceivable that the vaporized fuel control device stops supplying vaporized fuel to the engine. The air/fuel ratio fluctuates in synchronization with the stoppage, and especially in a low load range where the amount of intake air is small, there is a problem in that running stability is significantly reduced due to the influence of this fluctuation.

The present invention has been made in view of this point, and is an engine evaporation system that stops or reduces the supply from the canister only in the feedback zone high load region when the evaporative gas in the canister becomes empty in the evaporative fuel supply. An object of the present invention is to provide a fuel control device.

(Means for Solving the Problems) In order to solve the above problems, the present invention, as shown in FIG. In an engine in which an evaporative fuel supply passage and an intake passage are connected to each other through an evaporated fuel supply passage, a fuel supply means 101 supplies fuel to the intake system of the engine.
and a feedback zone detection means 102 for detecting a feedback zone; and when the feedback zone detection means detects that the engine operating region is in the feedback zone, an air-fuel ratio sensor detects the air-fuel ratio of exhaust gas. an air-fuel ratio control means 103 that feedback-controls the fuel supply means so that the air-fuel ratio of the air-fuel mixture supplied to the engine becomes a predetermined value based on a feedback correction amount based on the output; and at least a part of the feedback zone. A vaporized fuel supply means 104 that supplies the vaporized fuel through the vaporized fuel supply passage in an evaporated fuel supply region set as an operating region; and a high load in an operating region where the feedback zone and the evaporated fuel supply region overlap. When the high load region detecting means 105 detects the high load region and the high load region detecting means detects the high load region, and the feedback correction amount of the air fuel ratio control means exceeds a predetermined value set to the rich side, evaporation occurs. Evaporated fuel supply limiting means 1 for reducing fuel supply
0B, and.

(Operation/Effect) In the present invention, with the above configuration, only when the engine is in the feedback zone high load region, when the feedback correction amount exceeds a predetermined value set on the one-in side, the supply from the canister is restricted, It is possible to prevent the deterioration of running performance due to the air-fuel ratio becoming uniform by supplying air, and
This can prevent deterioration of running performance due to air-fuel ratio fluctuations in the low load region.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 2, an engine l has a combustion chamber 3 defined by a reciprocating piston 2;
An intake port 4 and an exhaust port 5, which are open to each other, are opened and closed by an intake valve 6 or an exhaust valve 7 at known timings in synchronization with the output shaft of the engine 1.

In the intake passage 8 connected to the intake port 4, an air cleaner 8, an air flow meter 10, a throttle valve 11, and a combustion injection valve 12 are disposed in order from the upstream side. Further, in the exhaust passage 13 connected to the exhaust port 4, an air-fuel ratio sensor 14 and a three-way catalyst 15 are arranged in order from the upstream side. 16 is a canister, this canister 16
is connected to a fuel tank 18 via a pipe 17 and to an intake passage 8 between the throttle valve 11 and the fuel injection valve 12 via a purge passage (evaporated fuel supply passage) 19. . An electromagnetic purge valve 20 is connected to the purge passage 19.

The canister 16 adsorbs evaporative gas (evaporated fuel) from the fuel tank 17 onto an adsorbent 16a therein, and temporarily stores the evaporative gas therein. Then, under predetermined operating conditions of the engine 1, the purge valve 2o
By opening the canister 16, the evaporative gas adsorbed by the adsorbent lea is purged together with air from the atmosphere communication port 16b in the canister 16 into the intake passage 8.

The aforementioned fuel injection valve 12 and purge valve 20 are controlled by a control unit 21 consisting of a microcomputer. To perform this control, Mt! The IJ unit 21 includes the aforementioned air flow meter 10. In addition to the signals from the air-fuel ratio sensor 14, signals from a rotation speed sensor 22 that detects the engine rotation speed and a water temperature sensor 23 that detects the temperature of the cooling water of the engine 1 are input.

Next, an example of control by the control unit 21 will be described with reference to the flowchart shown in FIG. After starting, first in step S1, the intake air amount Q, engine speed N, and engine load P detected by the air flow meter 10 are determined.

After reading, as shown in FIG. 4 in step S2, it is determined whether the current engine state is in the purge region. Specifically, the engine rotational speed N is 1
20Orpm <N <4500rpri and the engine load Pr is 1450 m [1g < P t<
It is determined whether the area is -100 smog.

When it is determined in step S2 that the area is a purge area, it is determined in step S3 whether conditions for purging evaporative gas are satisfied or not. The conditions for performing this purge are such that even if the evaporated gas is purged, the engine operation will not be significantly affected.For example, the cooling water temperature T must be at least a predetermined value (T>80°C), and the vehicle must be running at steady speed. It is considered a condition. If it is determined in step S2 that the area is not a purge area, or if it is determined in step S3 that the purge condition is not satisfied, the process moves to step S4 and no purging is performed.

If it is determined in step S3 that the purge condition is met, then the process moves to step S5, in which the feedback correction amount (hereinafter referred to as CFB), which is the integral of the signal from the air-fuel ratio sensor 14, is As shown in FIG. 5, it is determined whether CFB>α is greater than or equal to a predetermined value set on the Q side. The shift of CFB to the rich side means that the air-fuel ratio is on the lean side, and it is considered that the evaporative gas in the canister is empty and air is being supplied instead.

When CFB>α in step S5 above, step S
In step 6, it is determined whether the operating region is in the feed bank delay zone shown in FIG. 4, and if it is in the feedback delay zone, the process moves to step 4, and the process returns to the start without purge. Here, the feedback delay zone is a zone where the high load increase in fuel is temporarily delayed when transitioning from the feedback zone to the high load area, and is an area where feedback control is continued.

In step S5, if CFB≦α, or in step S6, if the operating region is not in the feedback delay zone, the process moves to step S7, purge is executed, and the process returns to the start.

Note that in step 4 of the flowchart, purge is stopped, which means that the purge valve is fully closed.

Although the embodiments have been described above, the present invention is not limited thereto.

In this embodiment, in step 6 in the flowchart,
The purge stop area is used as a feedback zone, but
A similar effect can be obtained in the high load area of the feedback zone.

Furthermore, the same effect can be obtained even if the purge is reduced when the purge is stopped.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is an overall system diagram showing an embodiment of the invention, Fig. 3 is a flowchart showing a control example of the invention, and Fig. 4 is an engine load and rotation speed. FIG. 5 is a diagram showing the time fluctuation of the feedback correction amount. 1... Engine 8... Intake passage 14... Air-fuel ratio sensor 16... Canister 16a... Adsorbent 19... Purge passage (evaporated fuel supply passage) 101...
-Fuel supply means 102... Feedback zone detection means 103...
・Air-fuel ratio detection means 104...Evaporative fuel supply means 105...High load region detection means 106...Evaporative fuel supply restriction means・'g 1 Figure + Y\

Claims (1)

[Claims] (1) In an engine equipped with a canister containing an adsorbent inside and storing evaporated fuel generated in a fuel tank, the canister and the intake passage are connected through an evaporative fuel supply passage, in which fuel is supplied to the intake system of the engine. a feedback zone detection means for detecting the feedback zone; and when the feedback zone detection means detects that the engine operating region is in the feedback zone, detects the air-fuel ratio of the exhaust gas. an air-fuel ratio control means for feedback-controlling the fuel supply means so that the air-fuel ratio of the air-fuel mixture supplied to the engine becomes a predetermined value based on a feedback correction amount based on the output from the air-fuel ratio sensor; an evaporative fuel supply region set in an operating region including a portion of the evaporative fuel supply region, in which the evaporative fuel supply means supplies the evaporative fuel via the evaporative fuel supply passage; and an operating region in which the feedback zone and the evaporative fuel supply region overlap. a high load area detection means for detecting a high load area; and when the high load area detection means detects a high load area and the feedback correction amount of the air fuel ratio control means exceeds a predetermined value set to the rich side; An evaporative fuel control device for an engine, comprising: evaporative fuel supply limiting means for restricting the supply of evaporative fuel.