JPS627950A - Fuel control device of engine - Google Patents

Abstract

PURPOSE:To prevent worsening of exhaust emission due to deterioration in purifying function, by a method wherein, under the colddown state of an exhaust purifying device, fuel cut motion during deceleration operation is stopped. CONSTITUTION:In an ECU 9, when the temperature of engine cooling water is decreased to lower than a given value in a given time after the starting of an engine, after a timer time for continuance of a warming-up state is set to a given value, an increase for rapid warming-up is effected during the set time by multiplying a fundamental injection amount by a given increase correcting factor. Until warming-up in the set time is completed, fuel cut control is not effected also in a fuel cut region during deceleration decided by a relation between the number of revolutions of an engine and the opening of a throttle valve 6, and exhaust emission is prevent from worsening due to fuel cut during deceleration under the colddown state of a catalyst converter 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel control device for an engine having a fuel cut function during deceleration operation.

(Prior art) Conventionally, in an automobile engine, it is detected that the engine is in a decelerating state based on, for example, changes in the throttle valve opening, engine speed, or intake negative pressure. Some engines are equipped with a fuel control device that cuts off the supply of fuel to the engine in order to improve the performance of the engine and prevent deterioration of the exhaust purification performance (see, for example, Japanese Patent Publication No. 11736/1983).

However, the improvement in exhaust purification performance due to the above-mentioned fuel cut in the fuel control device of such an engine is achieved in a relatively short period of time in which the temperature of the exhaust purification device itself does not fall below a predetermined temperature value that is the limit at which it can maintain its purification function. This is effective in the case of a fuel cut state for hours, but if the deceleration operation state continues for a long time, such as when going down a long slope, the continuation of the fuel cut state for a long time causes exhaust The temperature of the purification device falls below the predetermined temperature of the purification function maintenance limit, and the exhaust gas purification function is lost, which actually causes deterioration of exhaust emissions.

On the other hand, the state where the temperature of the exhaust purification device is below the predetermined temperature (hereinafter, this state will be defined as the cold state of the exhaust purification device) as described above is the same even during engine warm-up within a predetermined time after engine startup. Yes, for example, even if the vehicle decelerates after starting -l driving under incomplete warm-up conditions, the same $1 fuel cut control will be performed as in the case described in "-", which may also lead to worsening of exhaust emissions. There is sex. Also, if the engine speed drops rapidly after opening the throttle and increasing the engine speed by -[1] during rapid warm-up after engine startup, deceleration operation will occur and the fuel will be reduced due to the deceleration. When cut control is performed, a phenomenon similar to that described in -1- occurs. These are mainly due to the fact that the fuel cut control area due to deceleration is defined by the engine speed and throttle opening as shown in FIG.

(Object of the Invention) The present invention has been made based on the above-mentioned circumstances, and the present invention has been made in view of the above-mentioned circumstances. An object of the present invention is to provide a fuel control device for Ennon that prevents the deterioration of exhaust emissions due to the deterioration of the purification function of the fuel.

(Means for Achieving the Object) In order to achieve the objective 1-1, the engine fuel control device of the present invention includes a fuel cut control means for stopping the fuel supply during deceleration operation of the engine; In an engine equipped with an exhaust purification device, when the cold state detection means of the exhaust purification device and the cold state detection means detect that the exhaust purification device is in the cold state, the fuel cut control means operates. The apparatus is provided with an operation stopping means for stopping the operation.

(Function) According to the means described in 1-, if the engine has not been warmed up or if the fuel cut control state by two decelerations continues for a predetermined period of time under normal operating conditions, the relevant The fuel cut control state is automatically canceled, the temperature of the exhaust purification device is raised, and the exhaust purification function is restored. Therefore, a cold state at a temperature below a predetermined temperature that degrades the purification function of the exhaust gas purification device continues for a long time. This prevents deterioration of exhaust emissions as quickly as possible.

(Example) First, with reference to FIG. 1, an outline of the control system section common to the engine fuel control devices according to the first and second embodiments of the present invention described below will be explained, and then the above-mentioned A description of the control of the main parts of the embodiment will now be given.

First, in FIG. 1, reference numeral 1 is an automobile engine body, in which intake air is taken in from the outside via an air cleaner, and then passed through an air flow meter 2 and a throttle chamber 3.
The fuel is supplied to each cylinder via the ECU, which will be described later.
The fuel is injected by a fuel injection valve 5 controlled by an engine control unit 9. The amount of intake air into the cylinder is controlled by a throttle valve 6 provided in the throttle chamber 3, and the amount is detected by an air flow meter 2. The throttle valve 6 is operated in conjunction with the accelerator pedal, and is mostly closed (
(minimum opening).

On the other hand, the throttle chamber 3 is provided with a bypass passage 7 that bypasses the throttle valve 6, and this bypass passage 7 is provided with an electromagnetic electromagnetic engine that serves as a rotation speed adjustment means for controlling the engine rotation speed during idling. A valve (throttle valve) 8 is provided. Therefore, in the idling state, a portion of the intake air that has passed through the air flow meter 2 is supplied to each cylinder via the bypass passage 7, and the amount of supply is adjusted by the solenoid valve 8. be done.

The opening/closing state of the electromagnetic valve 8 is controlled by the duty ratio of a control pulse signal (hereinafter simply referred to as a control signal) supplied from the ECU'9.

In this case, the duty ratio is calculated by the following equation.

D=DB+DL+DFB However, DB: Fundamental term DL=Load correction term DFB: Feedback correction term E CtJ 9 is, for example, a microprocessor (CPU
) and 17, memory (ROM and RAM) and 3)
It is configured with an interface (j/(')) circuit. The -1- interface circuit of this ECU 9 includes a temperature sensor 4 such as a thermistor.
The temperature of the catalytic converter 11 detected by [
For example, the opening signal (TVO) of the throttle valve 6 detected by the button meter, the intake air amount detection signal Q detected by the air flow meter 2, and the engine rotation detected by the engine rotation speed detection means. Number (N)
, an engine starting signal S1 caused by key-on of the starter switch, an engine cooling water temperature detection signal T, and the like are respectively input.

17, reference numeral 10 indicates an exhaust pipe equipped with a catalytic converter 11 as an exhaust purification device, and the catalytic converter 11 described in -1- is provided with the temperature sensor 4 mentioned above to detect its temperature. It is graded.

By the way, in the system described in item 1, the fuel injection amount is controlled as follows.

That is, the fuel injection amount itself is determined by the pulse width (voltage application time) of the pulse signal supplied from the ECU Q, and the normal injection amount is determined by the intake air @Q detected by the air flow meter 2 and the engine rotation. It is determined by multiplying the basic injection amount cp determined by the number N by various correction coefficients. Here, the basic injection @Gp is Gp=1 per cylinder
It will be 20Q/NX. However, N is the engine speed, X is the number of cylinders, and Q is the intake air amount.

Next, control operations by the first and second embodiments of the control device described below will be explained in detail with reference to FIGS. 2 and 3, respectively.

First, the flowchart in FIG. 2 shows the fuel control operation of the first embodiment of the present invention when the exhaust gas purification device is in a cold state within a predetermined period of time after the engine is started.

That is, first, the control operation is started by supplying the engine start signal S by turning on the key of the starter switch 1. After the start of the control operation, a flag F'=O is set to indicate that the engine is in a cold state within a predetermined time. settings (step S,).

Next, the temperature of the engine cooling water, 1.1, is detected and manually controlled (step S2). Furthermore, in the same manner as above, the intake air amount Q (step S3), the throttle valve opening degree TVO
(Step S4), engine rotation speed N (Step S5)
Enter each.

Thereafter, it is determined whether or not the engine speed N has reached a predetermined reference value N1, for example, N+=30 Orpm (step S8). This judgment (step S,) continues until the actual engine speed N input in step S5 satisfies the condition N≧N+.
Following the operations of steps 82 to S5, the process is repeated a predetermined number of times. On the other hand, the above Ste, Tsubu S.

As a result of the judgment, if the condition N≧N1 is satisfied and the actual engine speed N is equal to or less than the reference value N, then (
If YES), then change the state to step S1 above.
Compare with the flag value (F' = O) set in
= 0, that is, it is determined whether or not it is within a predetermined time after the engine is started (step S?).

If the result is not F-0 (No), it means that the normal operating state has been entered, and as shown in FIG.
It is determined whether the fuel cut region (FC region) during deceleration is determined based on the relationship with VO (step S8
). As a result of this judgment, if the fuel is in the fuel cut area (YE
In step S), the injection pulse application time to the fuel injection valve 5 is set to 0 to cut fuel (step 5ll). On the other hand, -1
- If it is not in the fuel cut area in step S8 (NO)
In this step, fuel is injected into one cylinder at a basic fuel injection pulse of 120Q/NX per cylinder according to the engine speed N and intake air amount Q at that time (steps S, o).

Note that the above X indicates the number of cylinders. Thereafter, the operations of steps 82 to S10 are repeated at predetermined intervals.

On the other hand, if the result of the judgment in step S7 is F=0 (YES), the catalytic converter 11 as an exhaust purification device still reaches the predetermined temperature T within the predetermined time after the engine is started. In this case, first, the actual temperature T of the engine cooling water detected in step S2 is the predetermined temperature T. It is determined whether or not it has become -L (step S1). That is,
Here, the warm-up completion state of the catalytic converter II corresponding to the completion of warm-up of the engine is determined based on the engine cooling water temperature T1. As a result, the cooling water temperature T is the predetermined temperature T. In the following cases, after setting the timer one hour T to a predetermined value Ts for continuing the warm-up state (step 512), during the set time Ts, the fuel injection amount is -1- the basic injection! +200/NX is multiplied by a predetermined increase correction coefficient K to increase the amount for rapid warm-up (step 513).

Then, the timer's set time T=Ts is counted down at predetermined intervals (step S, 4), and finally it is determined that T=0 (step 5).
15). As a result, when T=0 (YES),
Set that state as flag 1 (step S, 6) t,
Then, the process moves to determination of the fuel cut area in the normal operating state after completion of warm-up (-operation in step S6 above). On the other hand, ′
If the warm-up is not completed (No) and the temperature is not r-0,
Repeat steps SI3 to SI6 above to 1゛-0.
The process continues repeatedly until (corresponds to the operation stopping means in the claims). On the other hand, step S described in -1-
II, the engine cooling water temperature T1 is the predetermined value T. , L is also high and the warm-up has already been completed, step S
+t~S Without performing the operations in step S14, proceed directly to step S+6 and flag (F-1) indicating completion of warm-up.
Execute the setting operation.

Therefore, according to the above control operation, fuel cut control will not be performed until the engine has warmed up within a predetermined period of time after starting, and the catalytic converter 11 will not be in the cold state corresponding to the engine cold state. Exhaust emissions do not deteriorate due to fuel cut during deceleration.

Next, FIG. 3 shows the fuel cut control operation even when the catalytic converter 11 is maintained in a cold state by continuing the fuel supply cut state for a predetermined time period in a predetermined time period after engine startup and in normal operating conditions. 12 shows a flowchart of a control operation according to a second embodiment of the present invention, in which the operation can be stopped. This embodiment is characterized in that the fuel cut operation is stopped by directly detecting the temperature of the catalytic converter II itself.

That is, when the control operation is first started by inputting the engine start signal S, the engine rotation speed N
1 intake air amount Q1 temperature of catalyst converter 11 j
+ is read for each E CU 9 above (
Step S+). Then, the temperature of the catalytic converter 11 [a predetermined temperature necessary for l to exhibit its catalytic function]. It is determined whether or not it is -1- (step S2).

As a result, the actual temperature t1 becomes t. In the above cases (YE
In step S), it is determined that the engine is sufficiently warmed up, and the process proceeds to a determination as to whether or not the engine is in a fuel cut region (PC region) due to deceleration operation (step S3). As a result of the determination, the change in engine speed at that time indicates a deceleration greater than a predetermined value,
If it is in the fuel cut region (YES), then a fuel cut operation (step S4) is performed, while if it is in the non-fuel cut region (N〇), the above basic fuel injection amount of +20Q/NX is calculated. A predetermined amount of fuel is injected based on the value (step S5).

On the other hand, in step S2 of "1", the temperature t1 of the catalytic converter 11 is t. In the following cold conditions (NO
) has an increase correction for rapid warm-up (120Q/NX)
Only K is performed (step S8). That is, this second
In the embodiment, this step S6 functions as operation stopping means in the claims.

Therefore, according to the above control operation, the actual temperature t1 of the catalytic converter 11 is the predetermined temperature t. In the following, fuel cut control is automatically stopped even in a deceleration state, and deterioration of exhaust emissions is prevented.

(Effects of the Invention) As is clear from the above description, the engine fuel control device of the present invention is effective for exhaust purification in an engine equipped with a fuel cut control means for stopping fuel supply during engine deceleration operation and an exhaust purification device. A cold state detection means of the device is provided, and when the cold state detection means detects that the exhaust purification device is in the cold state, the operation of the fuel cut control means is stopped, and the engine If the engine has not warmed up, or if a fuel cut state due to deceleration continues for a predetermined period of time under normal operating conditions, the fuel cut state is automatically canceled and the temperature of the exhaust purification device is increased. It is designed to restore the exhaust purification function. Therefore, a cold state at a temperature below a predetermined temperature that would degrade the purification function of the exhaust gas purification device does not continue for a long time, and deterioration of exhaust emissions is prevented as quickly as possible.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram common to each embodiment of the engine fuel control device according to the first and second embodiments of the present invention;
The figure is a flowchart showing the control operation of the engine fuel control system according to the first embodiment of the present invention, and FIG.
FIG. 4 is a flowchart showing the control operation of the engine fuel control device of the embodiment, and FIG. 4 is a graph showing the fuel supply stop region in the above control operation. 1... Engine body 2... Air flow meter 4... Temperature sensor 5... Fuel injection valve 6... Throttle valve 8... Solenoid valve 9e・・φ・ECU (Engine control unit) 11・・・・Catalyst converter 11 open% f62 7abU (1)

Claims (1)

[Claims] 1. In an engine equipped with a fuel cut control means for stopping fuel supply during deceleration operation of the engine and an exhaust purification device, the exhaust purification device is in a cold state by the cold state detection means of the exhaust purification device and the cold state detection means. A fuel control device for an engine, comprising: an operation stop means for stopping the operation of the fuel cut control means when the fuel cut control means is detected.