JPS61268837A - Control device for air-fuel ratio in engine - Google Patents

Abstract

PURPOSE:To prevent an engine stop, by controlling air-fuel ratio to a rich side for a fixed period of time when an engine is decelerated with its speed decreasing in an idle zone, in the case of the engine which provides an idle control valve to be arranged in a bypass path detouring a throttle valve. CONSTITUTION:When a vehicle is in running operation, a CPU30, driving a shift decision circuit 21, decides whether or not the present select lever is placed in a driving range or a reversing range, that is, whether or not the shift position is in the driving range. When a decision is YES, the CPU30, driving a zone decision circuit 22, compares an engine speed Ne in the present with the preset idle reset speed Ns. And when an engine is decided to be in a reset moment to an idle zone with the engine speed in a relation where Ne=Ns, the CPU30, calculating an air-fuel ratio correction amount to be richer than the air-fuel ratio in an ordinary idle condition, controls a fuel injection valve 16 so as to correct a fuel amount to be increased in accordance with said correction amount only for a fixed length of time.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention provides an automatic idle control valve disposed in a bypass path that bypasses the upstream and downstream of a throttle valve, and an automatic transmission equipped with a so-called torque converter. The present invention relates to an air-fuel ratio control device for an engine.

(Prior Art) Conventionally, an engine having a self-idle governor (hereinafter simply referred to as SIG) configured to control the opening and closing of the above-mentioned automatic idle control valve so that the rotation speed at idle becomes the target rotation speed has been disclosed in, for example, Japanese Patent Application Publication No. It is described in Publication No. 76723/1983.

When the automatic transmission is in a driving range such as drive range or reverse range in an engine equipped with the above-mentioned SIG and automatic transmission, when you pull the handbrake to put it in a braking state and then press the accelerator pedal to race, this happens. The problem was that the engine would stop when returning to racing.

Hereinafter, this point will be explained in more detail. In order to prevent the engine from stopping, the above-mentioned SIG does not function outside the idle zone and is opened to a predetermined opening degree.

This predetermined rotation is an opening degree that does not cause the engine to stop when the engine speed enters the idle zone after deceleration.

In addition, the above-mentioned 810 function is opened to a predetermined opening degree to prevent the engine from stopping when the engine decelerates and returns to the idle zone, as shown by the dotted line C in FIG.
The SAG is activated after a certain period of time t2 has elapsed from the deceleration point indicated by .

However, when the vehicle is idling in the drive range or reverse range, the brake is applied by the handbrake as described above, so a load is applied to the engine, and as a result, the target rotational speed becomes high.

Therefore, SIG increases the opening degree and increases the filling amount to increase the target rotation speed. On the other hand, when the charging jaffi increases in this way, the rotation of the engine becomes more stable, so the air-fuel ratio is made leaner and the ignition advance angle is advanced to improve fuel efficiency.

By the way, when racing back in the drive range or reverse range as described above, the load is on the engine in this state, so the engine rotation drops quickly and the engine stops easily. Since the ignition advance angle is advanced to the optimum value in the idle zone of the engine and reverse range, it is not preferable to control the ignition timing to prevent the engine from stopping.

(Purpose of the Invention) This invention focuses on the fact that when the automatic transmission is in the drive range, the air-fuel ratio of the engine intake air is on the verge of lean. To provide an air-fuel ratio control device for an engine that can increase torque by controlling the air-fuel ratio to a rich value when the above-mentioned racing return is reached.

(Structure of the Invention) This invention includes a detection means for detecting when an automatic transmission decelerates the engine in a drive range and the engine speed enters an idle zone, and a detection means for detecting that the engine speed has entered the idle zone, and An air-fuel ratio control device for an engine is characterized in that it is equipped with a control means for controlling an air-fuel ratio to be richer than an air-fuel ratio in a normal idle state.

(Effects of the Invention) According to the present invention, when the automatic transmission returns racing in a drive range such as a drive range or a reverse range, the above-mentioned detection means detects that the engine speed has reached the idle return speed. The above-mentioned control means operates based on the output of this detection means and makes the air-fuel ratio rich for a certain period of time, so the torque increases and as a result, the above-mentioned engine stop during racing return can be prevented. There is an effect that can be achieved.

(Example) An embodiment of the present invention will be described in detail below based on the drawings.

The drawing shows an air-fuel ratio control device for an engine. In FIG. 1, a piston 3 is disposed within a cylinder 2 of an engine 1, and the piston 3 and a crank 4 are connected by a connecting rod 5.

In addition, a spark plug 7 is provided in the combustion chamber 6, an intake valve 9 is provided on the intake boat 8 communicating with the combustion chamber 6, and an intake valve 9 is provided on the intake boat 8 to open and close the boat 8 as appropriate. 10 are respectively provided with exhaust valves 11 for opening and closing the boat 10 as appropriate.

Furthermore, an air flow meter 14, a throttle valve 15, and a fuel injection valve 16 are provided in the intake passage 13 leading from the air cleaner 12 to the above-mentioned intake boat 8, and an air flow sensor 14 is provided in the above-mentioned air 70-meter 14. 17, and a throttle opening sensor 18 is connected to the above-mentioned throttle valve 15, respectively.

Further, a bypass passage 19 is provided to bypass between the upstream and downstream sides of the throttle valve 15, and an automatic idle control valve 20 is disposed in the bypass passage 19.

By the way, the CPU 30 drives and controls the fuel injection valve 1.6, the automatic idle control valve 20, the shift determination circuit 21, and the zone determination circuit 22 according to the program stored in the ROM 31, and the RAM 32 stores the memory table shown in FIG. information, and necessary data such as the idle return rotation speed NS and the target rotation speed Nt at idle shown in FIG. 4 are stored.

Furthermore, the above-mentioned CPLI 30 receives a sensing signal from a drive range sensor (hereinafter simply referred to as D range sensor) 33 that detects that the select lever of the automatic transmission is in a state indicating the D (drive) stage for normal driving. Sensing signal from the reverse range sensor (hereinafter simply referred to as R range sensor) 34 that detects that the above-mentioned select lever is in the R (reverse) stage, air flow sensor 1
The air flow sensor signal U1 corresponding to the volumetric flow rate of intake air from 7, the throttle opening TVO from the throttle opening sensor 18, and the engine speed Ne are input, respectively.

The above-mentioned engine speed Ne can be obtained, for example, by converting the degree-by-degree signal with a frequency-voltage converter.

In this embodiment, the above-mentioned CPLI 30 performs detection that the engine speed Ne has entered the idle zone and rich control of the air-fuel ratio based on the detected output.

The operation of the engine air-fuel ratio control device configured as described above will be explained with reference to the flowchart shown in FIG.

In the first step 41, the CPU 30 drives the shift determination circuit 21 that determines the position of the select lever of the automatic transmission, and in the next second step 42, the CPU 30 drives the current Determining whether the select lever is in the drive range (hereinafter simply referred to as D range) or reverse range (hereinafter simply referred to as R range), that is, whether the shift position of the automatic transmission is in the drive range, When it is determined that the range is other than D range or R range, for example, parking range (P range) or neutral range (N range), the process ends.

On the other hand, there is a sensing signal from the above-mentioned D range sensor 33 or R range sensor 34, and in the above-mentioned second step 42, the CPU 3 determines that it is in the D range or R range.
If it is determined to be 0, in the next third step 43, the CPU
30 drives the zone determination circuit 22.

When the zone determination circuit 22 is driven, the engine speed Ne and the throttle opening TVO are input to the CPU 30.

Next, in a fourth step 44, the CPU 30 determines whether or not the engine speed Ne has returned to the idle zone by being sequentially decelerated based on the storage table shown in FIG.

That is, by comparing the current engine speed Ne and the preset idle return speed NS (see Figure 4),
When it is determined at -N5 that it is time to return to the idle zone, the process moves to the next fifth step 45.

In this fifth step 45, the CPU 30 calculates an air-fuel ratio correction m that is richer than the air-fuel ratio in the normal idle state shown in FIG. Accordingly, the aforementioned fuel injection valve 16 is controlled to perform, for example, a fuel increase correction, and the output of the fuel injection valve 16 is controlled in accordance with the above-described increase correction only for a certain period of time T1 preset by the CPLI built-in timer.

Further, in the fourth step 44 described above, the CPLI 30 is
If it is determined to be NS, in the next seventh step 47, C
The PU 30 determines whether or not the engine speed Ne is within the idle zone, and when determining that it is within the idle zone, proceeds to the fifth step 45 described above, and when determining that it is outside the idle zone. ends the process.

It goes without saying that after the predetermined time T1 has elapsed, the SIG operation is performed by the automatic idle control valve 20, and the engine speed Ne during idling is controlled to the target speed Nt.

In summary, when the shift position of the automatic transmission decelerates the engine in the drive range (see time t1 in Figure 4), and the engine rotation speed Net reaches the preset idle return rotation speed NS at time t2 in the figure, This is CPtJ30
, and based on this output, the above-mentioned CPLJ30 controls the air-fuel ratio to be rich as shown in the characteristic a in Fig. 4 for a certain period of time T1 set by the CPU built-in timer, so the engine speed Ne changes as shown in the characteristic in the same figure. As shown above, the drop is reduced and the torque increases. As a result, there is an effect that engine stoppage can be prevented during racing return under the above conditions.

In the correspondence between the configuration of the present invention and the embodiments described above, the detection means of the present invention corresponds to the first step 41 to the fourth step 44 in the processing flow of the embodiment, and similarly, the control means corresponds to the processing flow of the embodiment. Although this corresponds to the fifth step 45 to the sixth step 46 in , the present invention is not limited to the configuration of the above-described embodiment.

For example, the drive range may be a drive range, a reverse range, or a first or second speed range.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a system diagram showing an air-fuel ratio control device for an engine, and FIG.
FIG. 3 is an explanatory diagram of a storage table, FIG. 3 is a flowchart, and FIG. 4 is an explanatory diagram showing rich control of the air-fuel ratio. 1... Engine 15... Throttle valve 1
9... Bypass path 20... Automatic idle control valve 30... CPU 33... D range sensor 34... R range sensor

Claims (1)

[Scope of Claims] 1. An engine that is provided with an automatic idle control valve in a bypass path that bypasses between upstream and downstream of a throttle valve, and that is equipped with an automatic transmission, wherein the automatic transmission is in a driving range of the engine. A detection means for decelerating the engine speed and detecting that the engine speed has entered the idle zone, and controlling the air-fuel ratio to be richer than the air-fuel ratio in the normal idle state for a certain period of time from the time when the output of this detection means is received. An air-fuel ratio control device for an engine, comprising a control means.