JP3131744B2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for an engine in which an increased amount of fuel is supplied by asynchronous injection in addition to synchronous injection at normal timing during acceleration or the like.

[0002]

2. Description of the Related Art In general, a fuel injection system for an engine for an automobile or the like detects an intake air amount of the engine, and outputs an injection pulse having a pulse width corresponding to the intake air amount per rotation to a fuel injection valve. The fuel is injected at a predetermined crank angle in synchronization with the engine rotation. But,
By simply detecting the intake air amount and injecting the fuel in rotation synchronously based on the detected value in this way, when the accelerator is depressed, such as during acceleration, there is a delay in the detection of the intake air amount, and the injection itself is not performed. Also, there is a difference in timing, so that fuel shortage (overlean) occurs. Therefore, when acceleration is detected by a change in throttle opening, etc.,
Injection is performed without waiting for normal injection timing to increase the amount of fuel, and this is usually called asynchronous injection.

Japanese Patent Application Laid-Open No. 2-215944 discloses an example of a fuel injection system in which asynchronous injection is performed in addition to ordinary synchronous injection during acceleration.
In this publication, asynchronous injection is divided into a plurality of injections in order to improve fuel vaporization and atomization, and the number of divisions increases as the engine speed decreases.

[0004]

When the amount of fuel is increased by asynchronous injection when the accelerator is depressed during acceleration or the like, if the amount of fuel injected does not match the actual amount of change in the required torque, Excessive or deficient fuel causes overlean at low vehicle speeds such as when starting, resulting in poor running performance.On the other hand, unnecessary high fuel consumption during high-speed running results in poor fuel economy and poor emission performance. A problem arises.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in an engine in which fuel is increased by asynchronous injection, it is possible to prevent over-lean at a low vehicle speed such as at the time of starting and to secure high traveling performance. An object of the present invention is to improve fuel efficiency and emission performance by preventing unnecessary fuel increase at vehicle speed.

[0006]

According to the present invention, for example, in a state where the accelerator pedal is depressed at a low vehicle speed, there is a high probability that the vehicle is starting, and there is a high possibility that the required torque actually increases greatly. Therefore, in such a state, it is necessary to set the criterion for the execution of the asynchronous injection to the gentle acceleration side so as not to escape at the time of starting.On the other hand, for example, the state where the accelerator is depressed at a high vehicle speed is already considerable Since the torque is often generated, the situation where the torque is required to be further increased is less frequent, and therefore,
It is based on the finding that it is rather advantageous to avoid unnecessary fuel increase by setting the criterion for executing the asynchronous injection to the high acceleration side, and the configuration is as shown in FIG. is there. That is, the fuel control device for an engine according to the present invention includes a fuel injection valve that injects fuel into the engine in an amount corresponding to the pulse width of the supplied injection pulse, and a fuel injection valve that outputs a synchronous injection pulse synchronized with the rotation of the engine. Synchronous injection pulse supply means for supplying the output of the acceleration state detection means for detecting an acceleration state by a change in a parameter representing the load of the engine, and a change in the parameter is equal to or greater than a predetermined determination reference value. and the asynchronous injection pulse supplying means for supplying the asynchronous injection pulse to the fuel injection valve in addition to the synchronous injection pulses during, transmission formic
A request torque change predicting means for detecting a vehicle speed in a yawing state and predicting that a change in required torque of the engine is larger as the vehicle speed is lower; Asynchronous injection execution determination reference changing means for reducing the reference value, and prohibiting the supply of the next asynchronous injection pulse after the asynchronous injection pulse is supplied for a predetermined time, and prohibiting the asynchronous injection for increasing the predetermined time as the vehicle speed is lower. It has time changing means.

[0007] because request torque change is particularly large state, specifically the like at the start of the low vehicle speed, contrast,
Once running and maintaining a high vehicle speed, the required torque change width cannot be so large, so the magnitude of the required torque change can be predicted to some extent by the vehicle speed .

Further, when the required torque change is predicted based on the vehicle speed, if the transmission is in a neutral state, even if an acceleration state is detected, it is essentially an idle state and the required torque increases. Do not mean. Therefore, in the above configuration, the required torque change predicting means detects the vehicle speed and the neutral state of the transmission, and the asynchronous injection execution criterion changing means decreases the criterion value as the vehicle speed decreases, and Sometimes, even if the vehicle speed is low, the determination reference value may not be reduced.

Also, at low vehicle speeds such as when starting, there is a high probability that the required torque change width is large, while at high vehicle speeds, the required torque change width cannot be so large.
In the above configuration, an asynchronous injection pulse width changing means is provided,
It is preferable to increase the pulse width of the asynchronous injection pulse as the vehicle speed decreases.

[0010] Further, since the frequent use of the asynchronous injection may cause over-rich, it is preferable to provide the asynchronous injection inhibiting means so as to inhibit the next asynchronous injection for a predetermined time after the asynchronous injection is performed once. rather good, at that time, in the low vehicle speed side to a normal to the asynchronous injection is truly necessary is limited to the starting or the like, for example, even if you repeat the stop and start of the traffic congestion, the second time after is, is already vehicle If it is moving, it is not necessary to repeat the asynchronous injection.In addition, by repeating the asynchronous injection, the fuel becomes excessively filled.On the other hand, on the high vehicle speed side, the determination reference value for performing the asynchronous injection is originally set to the high acceleration side. Since it is highly probable that the required torque change is increased when the determination reference value is exceeded, it is necessary to prevent the timing from being missed. There is required. Therefore, the non <br/> synchronous injection prohibition time changing means as described above is provided, so that a longer time of the asynchronous injection prohibition higher vehicle speed is low.

[0011]

The synchronous injection pulse supply means supplies an injection pulse having a pulse width corresponding to the intake air amount per rotation of the engine to the fuel injection valve in synchronization with the rotation of the engine.
Fuel is injected into the engine at a predetermined injection timing.
Further, when an acceleration state in which a change in a parameter representing an engine load, for example, a throttle opening is equal to or greater than a predetermined determination reference value is detected, an asynchronous injection pulse is supplied to the fuel injection valve without waiting for the timing of synchronous injection, and As a result, an increased amount of fuel is injected into the engine. At that time, the determination reference value such as a change in the throttle opening that determines whether or not to perform the asynchronous injection is reduced when the vehicle speed is low, such as when starting, and therefore, when the required torque change is large, such as when starting. As a result, when the vehicle speed is high, the asynchronous injection is performed only in a situation where the required torque really increases.

The change in the required torque can be predicted by detecting the vehicle speed and the neutral state of the transmission. At this time, when the vehicle speed is low, the criterion value is not reduced even if the vehicle speed is low. Unnecessary fuel increase at the time of caulking is prevented.

In addition, the asynchronous injection pulse width changing means increases the pulse width of the asynchronous injection pulse as the vehicle speed decreases, thereby ensuring a fuel increase following a change in required torque at the time of starting or the like. Excessive fuel increase at high speeds is prevented.

Further, by prolonging the asynchronous injection prohibition time on the low vehicle speed side, excessive fuel increase after the fuel is once increased by the asynchronous injection at the time of starting or the like is prevented. Since the injection prohibition time is short, it is possible to reliably increase the acceleration without overlooking the required torque change on the high vehicle speed side.

[0015]

Embodiments will be described below with reference to the drawings.

FIG. 2 is an overall system diagram of an embodiment of the present invention. In this embodiment, the intake passage 2 of the engine 1
An air cleaner 3, an air flow meter 4, a throttle valve 5, and a surge tank 6 are provided in this order from the upstream, and a fuel injection valve 8 is provided at a position close to an intake port 7 of each cylinder. Each fuel injection valve 8 is controlled by a control unit 9 constituted by a microcomputer, and injects fuel toward the intake port 7 of each cylinder.
Therefore, the control unit 9 includes a rotation signal from a rotation sensor provided in a distributor 10 of an engine ignition system, an intake air amount signal from the air flow meter 4, and a water temperature sensor 11 for detecting an engine water temperature.
Water temperature signal from the engine and the exhaust passage 12 of the engine 1
, An oxygen concentration signal from an exhaust gas sensor 13 provided in the throttle valve 5, a throttle opening signal from a throttle sensor 14 attached to the throttle valve 5, a vehicle speed signal from a vehicle speed sensor for detecting vehicle speed, and a transmission A neutral switch signal or the like from a neutral switch for detecting a neutral state is input as information.

In the control unit 9, first, a basic injection amount is obtained in accordance with a value obtained by dividing an intake air amount detected by the air flow meter 4 by an engine speed obtained from an output of a rotation sensor, and various corrections based on an engine water temperature and the like are performed. And a feedback correction based on the output of the exhaust gas sensor 13 is added to the final injection amount.
An injection signal having a pulse width corresponding to the final injection amount is output to the fuel injection valve 8 at a predetermined crank angle for each cylinder based on the output of the rotation sensor. Thereby, each fuel injection valve 8 is opened, and injection synchronized with engine rotation is performed.

The control unit 9 calculates the amount of change in the throttle opening, and when the neutral switch signal is OFF, that is, when the transmission is in gear, the vehicle speed is equal to or less than a predetermined vehicle speed corresponding to the start (for example, 5 km / h or less). When the vehicle speed is low, acceleration is determined by a relatively low threshold value. If the threshold value is exceeded, an asynchronous injection pulse is output. At this time, the pulse width of the asynchronous injection pulse is assumed to correspond to the predicted required torque change at the time of starting the vehicle, and a relatively long time is set as the asynchronous injection inhibition time until the next asynchronous injection. On the other hand, if the vehicle speed exceeds the above-mentioned predetermined vehicle speed in the gear-in state, acceleration determination is performed based on a relatively high threshold value. Asynchronous injection pulse whose pulse width is smaller than that is output, and the asynchronous injection inhibition time is set relatively short. Also, in the neutral state, even at a low vehicle speed, the threshold value of the acceleration determination is set to be high as in the case of the high vehicle speed, the pulse width of the asynchronous injection pulse is reduced, and the asynchronous injection prohibition time is set. shorten.

By performing the asynchronous injection in addition to the synchronous injection as described above, the fuel increase is reliably and appropriately performed at the time of starting the vehicle, and unnecessary fuel such as at the time of congestion due to the repeated asynchronous injection is performed. The increase is prevented, and at high vehicle speeds and the like, the asynchronous injection can be performed while preventing unnecessary increase in the amount and without missing the timing at which the increase in the acceleration is required.

FIG. 3 is a flowchart for executing the injection control of the above embodiment. In addition, S1 to S18 indicate each step. Hereinafter, this flow will be described.

At the start, it is determined whether or not the vehicle is in a neutral state in S1, and if not, it is determined in S2 whether or not the vehicle speed is 5 km / h or less.

[0022] Then, not neutral, that is, if and vehicle speed is less 5km / h in the state of gear-reads the throttle opening TVO then in S3, this throttle opening S4 (TVO _n) and the previous throttle difference opening (TVO _n-1) is an acceleration determination on whether the predetermined value (threshold value) alpha ₁ or more.

[0023] If TVO _n -TVO _n-1 ≧ α ₁ at S4, then the timer value T which defines the asynchronous injection prohibition time in S5 to see whether zero. And
If T = 0, and starts the subtraction as well as set to an initial value T ₁ to T at S6.

[0024] Then, go to S7, to see if the timing of synchronous injection, if a timing of synchronous injection, in S8, outputs the asynchronous injection pulse of a predetermined pulse width T _P1. Also, if that matches the synchronous injection timing at S7, S9, the output normal synchronous injection pulses of the pulse width T _P and an injection pulse of the pulse width of the combined and the pulse width T _P1 asynchronous injection pulse I do.

If V _s ≦ 5 km / h is not satisfied in S2, or if it is determined in S1 that the vehicle is neutral,
10 reads the throttle opening TVO, the difference is a predetermined value of the current throttle opening (TVO _n) and the previous throttle opening (TVO _n-1) in S11 (threshold) alpha ₂ (where, alpha
See if ₁ <α ₂ ) or more.

If [0026] TVO _n -TVO _n-1 ≧ α ₂ at S11, the timer value T which defines the asynchronous injection prohibition time in this case in S12 to see whether zero. Then, if T = 0, T is replaced with the initial value T in this case in S13.
₂ (however, T ₁ > T ₂ ) and start subtraction.

Then, the flow goes to S14 to check whether it is the timing of the synchronous injection. If it is not the timing of the synchronous injection, an asynchronous injection pulse having a predetermined pulse width T _P2 (where T _P1 > T _P2 ) is output in S15. I do. If it is determined in S14 that the timing coincides with the timing of the synchronous injection, S16
In, and outputs a normal pulse width T _P synchronous injection pulse injection pulse having a pulse width obtained by combining the pulse width T _P2 asynchronous injection pulse in this case.

[0028] In addition, in the S4 or S11 TVO _n -TV
When O _n-1 does not reach the alpha ₁ or alpha ₂ is a threshold value for acceleration judgment, or threshold alpha ₁ or alpha respective timer value T even though ₂ reached in S5 or S12 is zero If not, since asynchronous injection is not performed, S
To see whether it is a synchronous injection timing to go to 17, and outputs a synchronizing pulse of a predetermined pulse width T _p in S18 when it is synchronous injection timing, to return.

[0029]

Since the present invention is constructed as described above, it is possible to prevent an over-lean at the time of low vehicle speed such as at the time of starting and secure traveling performance, and to increase an unnecessary amount of fuel at the time of high vehicle speed and neutral. To prevent fuel consumption and emission performance.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is an overall system diagram of an embodiment of the present invention.

FIG. 3 is a flowchart for executing control of the embodiment.

[Explanation of symbols]

 1 engine 8 fuel injection valve 9 control unit 10 distributor 14 throttle sensor

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F02D 45/00 312 F02D 45/00 312N (56) References JP-A-59-194052 (JP, A) JP-A-1-247732 (JP, A) JP-A-63-111250 (JP, A) JP-A-63-162946 (JP, A) JP-A-63-111250 (JP, A) JP-A-63-259133 (JP, A) 1984-49331 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/00-41/40 F02D 43/00-45/00

Claims (3)

(57) [Claims] 1. A fuel injection valve for injecting fuel into an engine in an amount corresponding to a pulse width of a supplied injection pulse, and a synchronous injection pulse for supplying a synchronous injection pulse synchronized with rotation of the engine to the fuel injection valve. Supply means, acceleration state detection means for detecting an acceleration state based on a change in a parameter representing a load of the engine, receiving the output of the acceleration state detection means, and synchronizing when the change in the parameter is equal to or greater than a predetermined determination reference value. Asynchronous injection pulse supply means for supplying an asynchronous injection pulse to the fuel injection valve in addition to the injection pulse, and detecting the vehicle speed in a gear-in state of the transmission, and as the vehicle speed decreases, the change in the required torque of the engine increases. Request torque change estimating means for predicting, and the output of the required torque change estimating means, wherein the larger the required torque change, the greater the criterion. An asynchronous injection execution criterion changing means for reducing the asynchronous injection pulse supply, and prohibiting the supply of the next asynchronous injection pulse for a predetermined time after the asynchronous injection pulse is supplied, and changing the asynchronous injection inhibition time to increase the predetermined time as the vehicle speed decreases. A fuel control device for an engine, characterized by comprising means. The demand torque change predicting means detects the vehicle speed and the neutral state of the transmission, and the asynchronous injection execution criterion changing means decreases the criterion value as the vehicle speed decreases. 2. The engine fuel control device according to claim 1, wherein the determination reference value is not reduced at times even when the vehicle speed is low. 3. An engine fuel control system according to claim 1, further comprising an asynchronous injection pulse width changing means for increasing the pulse width of the asynchronous injection pulse as the vehicle speed decreases.