JPH0740672Y2 - Air-fuel ratio controller for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an air-fuel ratio control device for an engine.

[Conventional technology]

Conventionally, for example, the fuel supply control device disclosed in Japanese Patent Laid-Open No. 53-8427 is known. This is a feedback control that corrects the fuel supply amount to the fuel injection valve in the normal operating region so that the air-fuel ratio becomes a predetermined theoretical air-fuel ratio, and in the high-load operating region of the engine, this high-load operating state is Only when it continues for a certain period of time, the feedback control is stopped so that the fuel supply amount to the fuel injection valve is increased more than the basic air-fuel ratio characteristic. That is, the increase correction (enrich correction) at the time of high load is delayed by a certain time and then performed.

In this device, since the condition of high-load operating condition is continued for a certain period of time, normal feedback control is performed when the engine temporarily enters the high-load operating region, and when the engine is truly in high-load operating condition. Only the engine output is increased.

[Problems to be solved by the device]

In a high load operation state, when the engine is in a relatively high temperature state, vapor is generated in the fuel, which may cause a shortage of the fuel supply amount. Even in such a state where the fuel characteristics are unstable, if feedback control is provided by uniformly delaying the enrichment correction, the feedback control may be delayed or hunting may occur. May cause deterioration of sex.

The present invention was made in order to solve such a conventional problem, and even if the normal operation state is changed to the high load operation state, the enrichment correction is performed by continuing the feedback control until then for a certain period of time. An air-fuel ratio control device for an engine that is delayed so that deterioration of fuel efficiency can be prevented even when the normal operating state is temporarily changed to a high load operating state, and the engine temperature is kept high in the high load operating state. It is an object of the present invention to provide an air-fuel ratio control device for an engine that can obtain a high output without deteriorating the drivability even if it is relatively high.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, an air-fuel ratio detecting means 14 for detecting an air-fuel ratio of an air-fuel mixture supplied to the engine 1 and an air-fuel ratio detecting means 14 as shown in the configuration explanatory view of FIG. Feedback control value calculation means A for calculating the feedback control value of the fuel injection amount from the fuel injection valve 9 based on the output of the fuel injection valve 9, and increase control value calculation means B for calculating the increase control value by correcting the fuel injection amount to increase. And an engine temperature detecting means 13 for detecting the temperature of the engine 1, and feedback control for outputting a control signal of the fuel injection amount based on the feedback control value in a preset operation range, and in a high load operation range. An injection amount control means C for performing an increase control for outputting a control signal of the fuel injection amount based on the increase control value, and the feed back controller when shifting to the high load operation region. A delay means D for delaying the change from the control to the increase control by a predetermined time, and a delay limiting means E for limiting the delay by the delay means D when the detected value of the engine temperature detecting means 13 is larger than a predetermined value are provided. Configured as follows.

[Action]

According to the above configuration, when the engine 1 is in a high temperature state where vapor is generated in the fuel, the execution of the increase control is executed without delay, thereby preventing deterioration of the drivability, and When the temperature is lower than the temperature, the shift to the enrichment correction is delayed, so the enrichment correction is not performed even if the engine is temporarily in a high load operation state, and feedback control is continued, which can prevent a reduction in fuel consumption. it can.

〔Example〕

FIG. 2 shows the overall structure of one embodiment of the present invention,
Reference numeral 1 is an engine, 2 is an intake passage for supplying intake air to a combustion chamber 3 of the engine 1, and 4 is an exhaust passage. An air cleaner 5, an air flow meter 6 for detecting the intake air amount, a throttle valve 7, a surge tank 8 and a fuel injection valve 9 are arranged in this order from the upstream side in the intake passage 2, and the fuel is injected from the fuel injection valve 9. The fuel is mixed with air and supplied to the fuel chamber 3 of the engine 1.

The distributor 10 of the ignition device is equipped with a rotation speed sensor 11 for detecting the engine rotation speed. The intake passage 2 is equipped with a throttle opening sensor 12 for detecting the opening of the throttle valve 7, and the engine 1 is equipped with a water temperature sensor (engine temperature detecting means) 13 for detecting the engine cooling water temperature. Further, the exhaust passage 4 is provided with an O ₂ sensor 14 as air-fuel ratio detecting means.

Reference numeral 15 is a control unit (ECU) that controls the fuel injection valve 9 and is composed of a microcomputer or the like. The control unit 15 includes an intake air amount detection signal from the air flow meter 6, a rotation speed detection signal from the rotation speed sensor 11, a throttle valve opening detection signal from the throttle opening sensor 12, and a water temperature sensor.
The water temperature detection signal from 13 is input.

Then, the control unit 15 outputs a signal (injection pulse) for controlling the injection time to the fuel injection valve 9 by controlling the injection time.

The control unit 15 includes the feedback control value calculation means A, the increase control value calculation means B, the injection amount control means C, the delay means D, the delay restriction means E and the like shown in FIG. That is, the control unit 15 first calculates the basic injection amount based on the intake air amount from the air flow meter 6 and the engine speed from the speed sensor 11. Then, in the operating region set in advance in the operating state determined by the engine speed and the throttle opening (the feedback zone inside the boundary indicated by the one-dot chain line in FIG. 3), the detected value of the O ₂ sensor 14 is determined. The feedback correction amount is calculated, the final injection amount (feedback control value) is calculated from the feedback correction amount and the basic injection amount, and the injection amount control means C outputs the corresponding control signal to the fuel injection valve 9 (feedback). Control).

Then, for example, in a high load operation region where the throttle opening or the like is larger than the set value (enrichment zone outside the boundary shown by the one-dot chain line in FIG. 3), the value (enhancement control value) obtained by enriching the basic injection amount is corrected. The calculation is performed and a control signal corresponding to the calculation is output to the fuel injection valve 9 (enrich control). Even in the above-mentioned enrichment zone, a feedback delay zone (indicated by a broken line in FIG.
In the area surrounded by the dotted line), if the engine temperature is within a predetermined range based on the engine temperature detected by the water temperature sensor 13, the high load operation state is continued (delayed) for a certain period of time, and then the increase control is performed. Enrichment control based on the value is performed, and if the engine temperature is out of a predetermined range, it immediately shifts to the enrichment control (limit of delay).

FIG. 4 is a flowchart showing a specific example of control of the fuel injection valve 9 by the control unit 15. In this flowchart, when starting, various sensor signals such as engine speed NE, throttle opening TVO, and water temperature THW are first input in step S ₁ .

In step S _2, whether the engine speed NE exceeds the predetermined rotation speed, i.e. examine whether the overspeed fuel cut zone, if the overspeed fuel cut zone, the step S ₃ A predetermined amount of fuel supply is cut by the overspeed fuel cut routine. This prevents the engine from burning due to excessive rotation.

If the overspeed fuel cut zone at the step S _2, whether or not the engine 1 in step S ₄ is in the predetermined decelerating region, i.e. examine whether the deceleration fuel-cut zone, deceleration fuel cut If it is in the zone, the fuel supply is cut by a predetermined amount by the deceleration fuel cut routine of step S ₅ . This makes it possible to maintain good emissions and improve fuel efficiency.

If the deceleration fuel cut zone at the step S _4, in step S ₆ the operating state checks whether or not it is enriched zone. If not in the enrichment zone, step
The feedback control routine of S ₇ outputs a control signal to the fuel injection valve 9 based on the feedback control value.

If in step S ₆ in Enrich zone, examines whether or not the engine speed NE is in a predetermined engine speed range _{(N 1 ≦ NE ≦ N 2} ) in step S _8, thereby even enriched zone Feedback Whether the vehicle is in the delay zone or not is judged from the engine speed. Engine speed NE is the control signal to the fuel injection valve 9 on the basis of the increasing control value by enriching routine of step S ₉ if the above engine speed range is output.

If the engine speed NE to the rotational speed range in step S _8, the predetermined value TVO ₁ throttle opening TVO at step S ₁₀
It is checked whether or not it is smaller, and it is judged from the aspect of throttle opening whether or not it is in the feedback delay zone. If the throttle opening TVO is larger than the above predetermined value, step S
Move to ₉ enrichment routine.

Smaller than a predetermined value TVO ₁ throttle opening TVO in step S _10, for operating conditions at this time in the feedback delay zone, the range further coolant temperature THW in step S ₁₁ in this case is in a predetermined (T ₁ ≦ THW ≦ T ₂ ) is checked, and if the water temperature THW is outside the above specified range, step S
Move to ₉ enrichment routine. This limits the delay processing described below.

A temperature (for example, 60 ° C.) assuming the state of the engine 1 before the warm-up operation is set is set as the lower limit T ₁ in the predetermined range of the water temperature, and vapor is generated in the fuel as the upper limit T _2. Such a temperature (for example, 80 ° C.) is set. Therefore, if the engine 1 is at a temperature higher than the upper limit value T _2, the injection amount from the fuel injection valve 9 is immediately enriched and corrected, whereby a high output can be obtained and the deterioration of the traveling property due to the vapor generation can be prevented. it can. Further, even when the engine 1 is at a temperature lower than the lower limit value T _{1, the} injection amount is immediately enriched and corrected, whereby the combustion performance at the time of cold engine is improved and the running performance can be prevented from deteriorating.

If the water temperature THW is within the predetermined range, the step S ₁₂ to S ₁₅
The delay processing (delayed by the delay means D treatment) X transition to Enrich routine of step S ₉ by a predetermined time delay by shifting to the Enrich routine after a certain time. Then, if the predetermined time has not passed, the feedback control routine of step S ₇ is executed. As a result, when the high load operation state is temporarily entered, the feedback control can be continued without performing the enrichment correction of the injection amount, and therefore the fuel consumption can be improved.

In the above delay process X, checks whether the instant the transition to enriching zone in step S _12, sets the predetermined time T ₀ to the timer T in step S ₁₃ if the moment of transition, the timer T in step S ₁₄ Is converted into a subtraction value T-1 and is counted down. In step S ₁₅ checks whether the timer T is zero, until zero to execute the feedback control routine of step S _7, to perform the enriched routine of step S ₉ if zero.

In the above embodiment, if the engine temperature is out of the predetermined temperature range, the enrichment routine (step S ₉ ) is immediately executed to limit the delay process. However, for example, step S ₁₁ and step S ₉ It is also possible to provide another timer between the above and the above and limit the execution of the enrichment routine after an extremely short time has elapsed.

Further, although the engine speed and the throttle opening are used as the parameters representing the operating state in the above-described embodiment, the present invention is not limited to this. For example, instead of the throttle opening, the intake air amount from the air flow meter 6 or the intake negative pressure is used. May be used.

Further, in the above embodiment, the upper limit value T _{2 is} set as the engine temperature condition.
And the lower limit value T ₁ are set, but for example, the upper limit value T ₂
Only the conditions may be set. As a result, it is possible to reliably prevent the deterioration of the traveling performance that is caused by delaying the enrichment correction, especially at high temperatures where vapor easily occurs in the fuel.

[Effect of device]

According to the air-fuel ratio control system for an engine of the present invention, in the high load operation state, when the engine is in a high temperature state where vapor is generated in the fuel, the execution of the increase control is executed immediately without delay. As a result, it is possible to reliably prevent the deterioration of the running property due to the generation of the vapor. Moreover, if the temperature is lower than the above temperature, the execution of the increase control is delayed, and therefore the increase control is not performed even if the high load operation state is temporarily entered, and the feedback control is continued. This can prevent deterioration of fuel efficiency.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view of the present invention, FIG. 2 is a schematic view of an apparatus showing an embodiment of the present invention, and FIG. 3 is a flow chart showing a specific example of dividing fuel control according to an operating state. A ... Feedback control value calculation means, B ... Increase control value calculation means, C ... Injection amount control means, D ... Delay means,
E: delay limiting means, 1 engine, 9 fuel injection valve, 13 water temperature sensor, 14 O ₂ sensor, 15 control unit.

Claims (1)

[Scope of utility model registration request] 1. An air-fuel ratio detecting means for detecting an air-fuel ratio of an air-fuel mixture supplied to an engine, and a feedback for calculating a feedback control value of a fuel injection amount from a fuel injection valve based on an output of the air-fuel ratio detecting means. Control value calculation means, increase control value calculation means for increasing and correcting the fuel injection amount to calculate an increase control value, engine temperature detection means for detecting engine temperature, and feedback control in a preset operating range. Feedback control that outputs a control signal of the fuel injection amount based on the value, and in the high load operation region, injection amount control means that performs the increase control that outputs the control signal of the fuel injection amount based on the increase control value; A delay means for delaying the change from the feedback control to the increase control for a predetermined time when shifting to a high load operation region; and the engine. Degree detecting means detected value the air-fuel ratio control apparatus for an engine, characterized in that a delay limiting means for limiting the delay by the delay means is greater than a predetermined value.