JPH0660582B2 - Engine fuel supply - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel supply system for an engine.

(Prior Art) Conventionally, in a fuel supply device for an electronically controlled engine,
In particular, the fuel supply at the time of engine start is performed by applying a fuel injection pulse having a pulse width corresponding to the cooling water temperature to the fuel injector with reference to the cooling water temperature of the engine as shown in FIG. The amount of increase increases at lower water temperatures (see, for example, Japanese Patent Laid-Open No. 52-139830). Therefore, according to such a conventional technique, the starting fuel amount is determined only by the cooling water temperature at that time, irrespective of the cranking time from engine start, that is, from when the starter switch is turned on to when the engine is completely detonated. Become. Once the engine has completely exploded, the fuel amount in the idle state after the complete explosion is transiently corrected. In this case as well, the supplied fuel amount is determined based on the coolant temperature. It has become.

However, the cranking time is not constant and varies considerably depending on the starting state. Therefore, even if the engine speed (for example, 300 rpm) during cranking is constant, for example, when the cranking time at that time is 3 seconds and 5 seconds, the air-fuel ratio ( A / F) is
There will be a considerable difference, and the wetting of the spark plug will also differ greatly. As a result, if the idle supply fuel amount after the complete explosion is determined based on only the cooling water temperature in this state as in the above conventional technique, the optimum air-fuel ratio cannot be obtained and the combustion state becomes unstable. And become a rough idol. In addition, the air-fuel ratio of the exhaust gas supplied to the exhaust purification device also becomes high in concentration, which causes deterioration of exhaust emission. Furthermore, unnecessarily setting the air-fuel ratio to a rich state has various problems such as deterioration of fuel efficiency.

(Object of the Invention) The present invention has been made to solve the above problems, and solves the above problems by correcting the reduction of the supplied fuel amount according to the cranking time after the complete explosion of the engine. An object is to provide a fuel supply system for an engine.

(Means for Achieving the Purpose) In order to achieve the above-mentioned object, the fuel supply system for an engine of the present invention is based on the intake air amount to the engine as illustrated in FIGS. 1 and 2. In a fuel supply device for an engine that supplies a predetermined amount of fuel to the engine by correcting with a predetermined correction signal in accordance with an operating state, a complete explosion detection means for detecting complete explosion of the engine,
A cranking time detecting means for detecting a cranking time from engine start to a complete explosion in response to an output of the complete explosion detecting means, a predetermined starting fuel amount at the time of cranking, and an output of the cranking time detecting means. Received,
A decrease amount correction means is provided for correcting the supplied fuel amount in an idle state within a predetermined time after the complete explosion of the engine with respect to the starting fuel amount as the cranking time increases.

(Operation) According to the above means, the fuel supply amount is greatly reduced as the cranking time is longer during a predetermined time after the complete explosion of the engine, depending on the cranking time until then. Therefore, it becomes possible to appropriately correct and correct the difference (fluctuation) in the air-fuel ratio immediately after the complete explosion due to the difference in cranking time (long and short), and it is possible to correct the difference in cranking time (long and short). Since it is possible to always obtain a stable air-fuel ratio, the idle speed is stabilized, exhaust emission is not deteriorated, and fuel efficiency is improved.

(Embodiment) FIGS. 1 to 5 show an engine fuel supply apparatus according to an embodiment of the present invention.

First, the outline of the control system of the above-described embodiment apparatus of the present invention will be first described with reference to FIG. 1, and then the control of the main part will be described.

In FIG. 1, reference numeral 1 is an engine body, intake air is sucked from the outside through an air cleaner, and then supplied to each cylinder through an air flow meter 2 and a throttle chamber 3, and fuel is supplied by an ECU 9 as described later. It is adapted to be injected by a controlled fuel injector 5. The amount of intake air to the cylinder is controlled by the throttle valve 6 provided in the throttle chamber 3, and the amount is detected by the air flow meter 2. The throttle valve 6 is interlocked with the accelerator pedal, and is maintained at the minimum opening degree in the idle operation state.

On the other hand, the throttle chamber 3 is provided with a bypass passage 7 that bypasses the throttle valve 6.
The bypass passage 7 is provided with a solenoid valve (throttle valve) 8 that serves as an air amount adjusting means for controlling the engine speed during idling. Therefore, in the idle operation state, the intake air that has passed through the air flow meter 2 is supplied to each cylinder through the bypass passage 7, and the supply amount is adjusted by the solenoid valve 8. This solenoid valve 8
The open / closed state is controlled by the duty ratio of the control pulse signal supplied from the engine control unit (hereinafter abbreviated as ECU) 9.

On the other hand, the fuel injector 5 has a filter 16
Also, it is connected to the fuel tank 14 via the fuel pump 15. Reference numeral 17 is a pressure regulating valve provided on the return side of the fuel supply line.

The ECU 9 mainly includes, for example, a microprocessor (CPU), and includes a memory (ROM and RAM) and an interface (I / O) circuit. The interface circuit of the ECU 9 includes, for example, an engine start signal S generated when the starter switch (ST switch) 13 is turned on, a cooling water temperature detection signal T of the engine body 1 detected by a thermistor, and a throttle detected by a potentiometer, for example. The opening signal TVO of the valve 6, the intake air amount detection signal Q detected by the air flow meter 2, and the crank angle signal C detected by the crank angle sensor 12 are input at various angles.

The fuel in the fuel tank 14 is partially supplied to the fuel injector 5 through the filter 16 by the fuel pump 15 as described above, and the ECU 9
The fuel injection pulse F ₀ supplied from the fuel injector 5 supplies the fuel to the engine, while other excess fuel flows through the pressure regulating valve 17 to the fuel tank 14.
Returned to. The fuel injection pulse F ₀ is generally calculated based on the following equation.

F ₀ = Fp · α (1 + K ₁ + K ₂ + K ₃ + K ₄ ) K _F c · K _D +
Fs ・ ・ ・ (1) However, Fp: Basic injection pulse α: Air-fuel ratio feedback correction value K ₁ : Start-up increase correction value K ₂ : Water temperature correction value (relative to low water temperature) K ₃ : Idling increase correction value K ₄ : Air-fuel ratio correction value K _F c: Fuel cut correction value K _D : Reduction correction coefficient (to cranking time) Fs: Voltage correction value Reference numeral 10 indicates an exhaust pipe equipped with a three-way catalytic converter 11. There is.

Next, the control operation of the above control device will be described in detail with reference to FIG.

When the control operation is first started, first, various input information described above, that is, the crank angle signal C, the intake air amount signal Q, the engine start signal S, and the water temperature signal T of the engine cooling water are given at predetermined time intervals. It is read (step S ₁ ), and then the ON state of the starter switch (ST switch) is determined based on the input state of the engine start signal S (step S ₂ ). When the result of this determination is YES, that is, when the engine is in the start starting state, it corresponds to the pulse width determined by _first multiplying the basic injection pulse Fp of the above formula (1) by the startup increase correction coefficient K _1. injection was started fuel (step S ₄₎ is performed. It should be noted that the correction amount of the starting fuel is set to a predetermined water temperature (for example, 1
When the idle contact is ON above 0 ° C, that is, when the idle region is reached, the amount is reduced (transient increase).

On the other hand, when the starter switch in step S ₂ is NO OFF, goes further ON previous starter switch in step S _3, it is determined OFF state. Then, if the current state is OFF but the last time is ON, YES, first, the fuel increase rate (water temperature correction value) according to the water temperature T of the engine cooling water.
K ₂ is calculated (step S ₅ ), and a predetermined correction coefficient K _D corresponding to the cranking time t is calculated in step S ₆ . As described in the section of the prior art, the correction coefficient K _D depends on the cranking time because the air-fuel ratio (A / F) in the combustion chamber immediately after the complete explosion is different. This is for correcting the fuel injection amount at the time of idling immediately after that by a predetermined amount reduction correction (in addition to the original idle correction), and as shown in FIG.
The coefficient value can be changed according to t. Then, in the next step S ₇ , the time a for performing the correction is calculated according to the engine speed during the cranking,
The set time of the control time setting timer T _M based on the correction coefficient K _D is set to a. This set time a is set corresponding to the detection value from the cranking time detection means of the engine. On the other hand, in step S _3, if the previous even starter switch is NO OFF, the that is, when the cranking is completed, first the fuel increase rate K ₂ is calculated in accordance with the temperature T at that time in step S _8, then In step S ₉ , the fuel increased by the increase rate K ₂ is injected as the fuel supply amount during idling.

Next, when the control time a is set in step S ₇ , then it is determined in step S ₁₀ that T _M = 0, that is, the elapse of the set time a. If this judgment result is NO,
That is, within the set time a, in step S ₁₁ , K is obtained by multiplying the increase rate K ₂ by the correction coefficient K _D.
Fuel is injected with the increase value of _D × K ₂ (reduction correction). Then, further to continue the operation of the steps S ₁₀ to S ₁₂ until the routine proceeds to step S ₁₂ sequentially counts down the time of the timer T _M (T _M -1) completely time-up. Therefore, by the operation of the steps S ₅ to S ₁₂ are supplied fuel to the engine in an idle state after complete爆直is corrected to an appropriate amount in accordance with the cranking time t (4
(See figure). On the other hand, the result of the determination in step S ₁₀ is T _M =
When 0, that is, when the set time a has elapsed, fuel is injected at an increase rate of K _D × K ₂ while gradually returning the correction coefficient K _D to 1 (step S ₁₃ ).

More Step S ₆ to S ₇ and the results of the control operations of steps S ₁₀ to S _12, the fuel supply amount in the idling state of the engine complete explosion is corrected in accordance with the cranking time as indicated by the characteristic of FIG. 4 For example, as shown in FIG. 5, the smaller the cranking time t, which corresponds to the water temperature,
On the other hand, the final increase rate (K ₂ = K _D · K ₂ ) is determined such that the smaller the cranking time t, the larger the cranking time t.

(Effects of the Invention) As described above, the engine fuel supply system of the present invention is based on the intake air amount to the engine, and corrects it by a predetermined correction signal according to the operating state. In a fuel supply device for an engine that supplies a predetermined amount of fuel, a complete explosion detection means for detecting the complete explosion of the engine, and a cranking time for detecting the cranking time from the engine start to the complete explosion by receiving the output of the complete explosion detection means. While supplying a predetermined starting fuel amount at the time of cranking and the cranking time detecting device, the supplied fuel amount in the idle state within a predetermined time after the complete explosion of the engine is set to the starting fuel amount. On the other hand, the present invention is characterized in that a decrease amount correction means for increasing the decrease amount as the cranking time increases is provided.

Therefore, according to the present invention, during the predetermined time after the complete explosion of the engine, the fuel supply amount is greatly reduced as the cranking time is longer according to the cranking time until then. Therefore, it becomes possible to appropriately correct and correct the difference (fluctuation) in the air-fuel ratio immediately after the complete explosion due to the difference in cranking time (long and short), and it is possible to correct the difference in cranking time (long and short). Since it is possible to always obtain a stable air-fuel ratio, the idle speed is stabilized, exhaust emission is not deteriorated, and fuel efficiency is improved. Further, since the above-mentioned reduction correction is not performed except in the idle state, there is no possibility that the traveling performance is deteriorated, for example, when the vehicle is traveling under a high load where a high concentration air-fuel ratio is required.

[Brief description of drawings]

FIG. 1 is a control system diagram of a fuel supply system for an engine according to an embodiment of the present invention, FIG. 2 is a flowchart showing a control operation of the apparatus of the same embodiment, and FIG. 3 is a control operation of FIG. FIG. 4 is a graph showing the relationship between the cranking time and the correction coefficient for the cranking time, FIG. 4 is a graph showing the relationship between the cranking time and the fuel increase rate in the control operation of FIG. 2, and FIG. FIG. 6 is a time chart showing the function and effect of the present invention, and is a graph showing a fuel injection pulse width characteristic at the time of conventional start. 1 ... Engine body 2 ... Air flow meter 5 ... Fuel injector 6 ... Throttle valve 7 ... Bypass port 8 ... Solenoid valve 8 9 ... Engine control unit 13 ... Starter switch 14 ... Fuel tank

Claims (1)

[Claims] 1. A fuel supply device for an engine, which supplies a predetermined amount of fuel to the engine by correcting the amount of intake air to the engine by a predetermined correction signal according to an operating condition. Complete explosion detection means for detecting an explosion, cranking time detection means for detecting the cranking time from engine start to complete explosion by receiving the output of the complete explosion detection means, and supplying a predetermined starting fuel amount at the time of cranking. Along with the output of the cranking time detection means, a reduction correction means for correcting the supplied fuel amount in the idle state within a predetermined time after the complete explosion of the engine with respect to the starting fuel amount to be greatly reduced as the cranking time is longer. An engine fuel supply device characterized by being provided.