JPH08200126A - Stability controller for engine - Google Patents

Abstract

PURPOSE: To prevent sufficient acceleration from being disenabled just after starting in using fuel on the light side. CONSTITUTION: The warming-up time fuel amount coping with heavy fuel and acceleration after starting is calculated by a calculating means 21, and the warming-up time fuel amount coping with fuel on the side lighter than the heavy fuel is calculated by a calculating means 22. The stability to be calculated by a stability calculating means 23 and the specified slice level is compared with each other by a comparing means 24, and a supplying means 25 supplies the warming-up time fuel amount coping with heavy fuel to an intake pipe before the stability is less than the slice level and supplies the warming-up time fuel amount on the light side when the stability is less than the slice level. When this supply fuel amount is excess of the specified value, a prohibiting means 26 prohibits calculation of stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine stability control device.

[0002]

2. Description of the Related Art In an engine equipped with an electronically controlled fuel injection device, fuel is injected from a fuel injection valve to an intake port or the like. In this case, during warm-up when a large amount of fuel adheres to the intake port and intake valve, Properties of fuel used (mainly volatile)
Because the amount of fuel actually sucked into the cylinder varies greatly depending on the difference in fuel consumption, when the amount of fuel supplied during warm-up is set to the standard fuel, when heavy fuel is used, the mixing ratio Becomes lean. On the other hand, in order to avoid making this mixture ratio lean, if the fuel supply amount during warm-up is set for the heaviest fuel, the fuel supply amount becomes excessive when using the lighter fuel than this fuel The ratio becomes rich.

Therefore, the warm-up fuel amount is set in correspondence with the heaviest fuel and the fuel on the lighter side than this fuel, and the warm-up fuel amount corresponding to the heaviest fuel is used. By starting the operation immediately after the start-up, the operability is ensured even during the warm-up even when the heaviest fuel is used, while the stability of the engine is calculated and compared with a predetermined slice level. When the stability becomes less than the slice level, it is judged that the fuel on the light side is being used, and the amount of fuel during warm-up is switched to support the fuel on the light side, thereby mixing during warm-up when using the fuel on the light side. It has been proposed to prevent the ratio from becoming rich (see Japanese Patent Application Laid-Open No. 2-5744).

[0004]

An actual vehicle is used for setting the warm-up fuel amount (specifically, the water temperature increase correction coefficient Ktw and the post-starting increase correction coefficient Kas) corresponding to the heaviest fuel. , Even if acceleration is performed immediately after starting, the value on the increasing side is set further than that for steady-state so that jerky vibration or engine stall due to lack of fuel does not occur. If such a setting is for acceleration after startup, it may be for fast idle.

The difference between the two is shown in FIG. 6. When the warm-up fuel amount for fast idle is used, the stability index (stability) falls within an appropriate range during fast idle (see the upper dashed line). On the other hand, according to the warm-up fuel amount for post-start acceleration, it is on the increase side compared to the fast idle type, so stability starts from good and moves to an appropriate region over time (upper stage). See the solid line). It should be noted that a suitable region is a region that is higher than the slice level SL2 indicated by the broken line and lower than the slice level SL1 indicated by the solid line in the upper part of FIG. 6, and a good region is a region lower than the slice level SL2. However, it has been found that if the conventional device is operated as it is with respect to such a warm-up fuel amount that is compatible with post-start acceleration, the post-start acceleration cannot be supported.

For example, as shown in FIG. 7, if the stability is in a good region at the control start timing t1 in the stability feedback control performed based on the comparison result of the stability and the slice level, the light fuel can be used. It is judged that there is, and the control amount corresponding to the fuel on the light side is switched to, and the stability which was good by this switching immediately shifts to an appropriate region. If the vehicle is accelerated at this moment, the fuel amount during warm-up will be insufficient and sufficient acceleration will not be performed, which may cause engine stall.
Even if it is not accelerated, the amount of fuel during warm-up is gradually reduced with the passage of time, so stability gradually shifts to a bad region, and at that timing the control amount for the heaviest fuel is returned to. Be done. The reason why we moved to the bad area is because we switched to the fuel for the lighter side, and if we did not switch from the beginning, we would not move to the bad area.

Therefore, according to the present invention, when a warm-up fuel amount corresponding to heavy fuel and acceleration after starting is supplied to start the operation immediately after starting, when the supplied fuel amount is equal to or more than a predetermined value, it is stable. By prohibiting the calculation of the degree and the comparison between the stability and the slice level, it is an object to prevent a situation in which sufficient acceleration is not performed immediately after the start.

[0008]

The first aspect of the present invention, as shown in FIG. 13, is a means 21 for calculating the warm-up fuel amount for heavy fuel and for acceleration after starting, and a means 21 for calculating the warm-up fuel amount. A means 22 for calculating the warm-up fuel amount corresponding to the light fuel, a means 23 for calculating the stability of the engine, and a means 24 for comparing the calculated stability with a predetermined slice level,
Based on the result of this comparison, the warm-up fuel amount corresponding to the heavy fuel is sucked before the stability becomes lower than the slice level, and the warm-up fuel amount on the light side is sucked when the stability becomes lower than the slice level. A means 25 for supplying the respective pipes and a means 26 for inhibiting the calculation of the stability when the supplied fuel amount exceeds a predetermined value are provided.

As shown in FIG. 14, the second aspect of the present invention relates to a means 21 for calculating the warm-up fuel amount corresponding to heavy fuel and acceleration after start-up, and a fuel corresponding to a lighter fuel side than the heavy fuel. Means 22 for calculating the warm-up fuel amount, means 23 for calculating the stability of the engine, means 24 for comparing the calculated stability with a predetermined slice level, and the stability is sliced based on the comparison result. A means 25 for supplying the warm-up fuel amount corresponding to the heavy fuel before the level falls below the level, and the warm-up fuel amount for the light side to the intake pipe when the stability falls below the slice level, Means 31 for prohibiting the comparison between the stability and the slice level when the supplied fuel amount exceeds a predetermined value is provided.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the predetermined value is set so as to increase as the engine temperature decreases in accordance with the engine temperature.

[0011]

[Operation] When warming up for heavy fuel and accelerating after startup When starting operation immediately after startup with the fuel amount, the stability became less than the slice level, so during warm up for light fuel When the amount of fuel is switched to and the accelerator pedal is depressed greatly immediately after the switching, the amount of increase during warm-up may be insufficient and acceleration may not be sufficient or engine stall may occur. On the other hand, in the first aspect, when the supplied fuel amount exceeds the predetermined value, the calculation of the stability is prohibited, so that the stability and the slice level are not compared. The engine will continue to operate using the warm-up fuel amount that is compatible with heavy fuel and supports acceleration after startup, so that even if the accelerator pedal is fully depressed immediately after startup, sufficient fuel for acceleration is supplied. Therefore, the setting for acceleration after starting is fully utilized.

According to the second aspect of the present invention, even if the comparison of the stability and the slice level is prohibited when the supplied fuel amount exceeds a predetermined value, it is sufficient to respond to the acceleration when the accelerator pedal is fully depressed immediately after the start. Fuel is supplied and the setting for acceleration after start is fully utilized.

According to the third aspect of the invention, the predetermined value is set to be larger according to the engine temperature as the engine temperature decreases, so that the setting accuracy of the predetermined value is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an engine body, a fuel injection valve 7 is provided in an intake passage 8 downstream of an intake throttle valve 5, and the injection valve 7 responds to a signal from a control unit 2. Then, fuel is injected and supplied into the intake air so that a predetermined air-fuel ratio is obtained.

In the control unit 2, a rotation speed signal from the crank angle sensor 4, an intake air amount signal from the air flow meter 6, an air-fuel ratio (oxygen concentration) signal from the oxygen sensor 3 installed in the exhaust passage 9, and The cooling water temperature signal from the water temperature sensor 11, the gear position signal from the gear position sensor 12 of the transmission, etc. are input, and based on these signals, the control unit 2 operates so that the three-way catalyst 10 works at maximum conversion efficiency. In addition to feedback control of the fuel ratio, during warm-up when the engine state becomes unstable, the air-fuel ratio on the rich side of the theoretical air-fuel ratio is used for operation, so the post-start increase correction coefficient Kas and the water temperature increase correction coefficient Ktw are used. Correct the fuel warm-up increase. Specifically, the fuel injection pulse width Ti given to the injection valve 7 is calculated by the following formula: Ti = (Tp + KATHOS) × TFBYA × (α + αm−1) × 2 + Ts (1) TFBYA = Ktw + Kas + KHOT + KMR (2) Is converted into a drive pulse at the injection timing of and is output to the injection valve 7.

Here, in the equation (1), Tp is a basic pulse width calculated by the equation of Tp = K × Q / Ne from the intake air amount Q and the engine speed Ne, and KATHOS is in accordance with the cooling water temperature Tw and the like. Pre-set wall flow correction amount, TFB
YA is a target fuel-air ratio, α is an air-fuel ratio feedback correction coefficient, αm is an air-fuel ratio learning value, and Ts is a voltage correction coefficient added according to the battery voltage to correct the invalid time of the injection valve. Further, in the equation (2), KHOT is a high water temperature increase correction coefficient, KMR is an air-fuel ratio correction coefficient, and KHOT is used during warm-up.
T = 0% and KMR = 100%.

2, FIG. 3 and FIG. 4 are characteristic diagrams of the injection pulse width at start Tist, the water temperature increase correction coefficient Ktw, and the after-start increase correction coefficient (to be exact, the initial value) Kas. As various fuels with different volatility are used, these values become the largest when the heaviest fuel is used, and when the lightest fuel is used, as shown in FIG. These values are the smallest.

In this case, the above Tist and K corresponding to two fuels, the heaviest fuel and the fuel on the lighter side than this fuel, respectively.
Since tw and Kas are prepared in advance and priority is given to ensuring drivability when using the heaviest fuel, Ti for the heaviest fuel is used.
While starting the operation using st, Ktw, Kas,
When it is found from the comparison result of stability and slice level that the fuel on the light side is used, by switching to the operation using Ktw and Kas for the fuel on the light side, the fuel on the light side is used. It is possible to prevent the mixture ratio from becoming rich during the warm-up of.

By the way, the Kt for the heaviest fuel is prevented so that the vibration and the engine stall do not occur even when the vehicle is accelerated immediately after the start.
If w and Kas are set to support acceleration after starting,
If the conventional device is used as it is, sufficient acceleration may not be performed after starting. In order to cope with this, in the control unit 2, when the operation immediately after the start is started by using the supply fuel amount for the heaviest fuel and for the post-start acceleration, when the supply fuel amount (Ti) is equal to or more than a predetermined value. Prohibits the comparison between the stability and the slice level so that sufficient acceleration can be performed even if the acceleration is performed during warm-up when using the light fuel.

The contents of this control executed by the control unit 2 will be described with reference to the following flow chart.

First, FIG. 8 calculates the stability of the engine, which is executed every 180 degrees in crank angle.

In step A), the old value of the cycle TREF during REF (reference signal for every 180 degrees of the crank angle sensor 4) is shifted and the previous data is stored in the previous RAM two times.
And again, moving from three times to four times. Step B)
Now calculate a new TREF.

Steps C) to G) are portions for determining whether or not the rotation fluctuation is detected, which is steps C) to G).
Check the contents one by one and judge that it is the detection area when all of the items are satisfied,
If even one is not, it is judged that it is not in the detection area. That is, step C): at idle, step D): neutral, step E): auxiliary equipment load is not operating, step F): predetermined time has elapsed after starting, step G): When the rotation speed deviation from the target rotation speed NSET is within the allowable value DRFOK1, it is judged as a detection area and the process proceeds to step H). When either of them is not satisfied, it is judged that it is not in the detection area and the routine of FIG. To finish.

In step H), the old value of the cylinder-by-cylinder variation amount TREFC in the REF cycle is shifted in the same manner as the TREF shift, and in step I) the new TREFC is changed.
TREFC = TREF−TREF _n−4 (3) where TREF _n−4 ; calculated by the formula of TREF four times before.

In this case, a four-cylinder engine is taken as an example, and TREFC is the amount of change in the REF-interval cycle of this time with respect to the REF-interval cycle of the previous combustion of the own cylinder (combustion cylinder four times before). The reason why the variation amount is taken for each cylinder is to prevent the variation between the cylinders from being mistakenly recognized as a variation.

In step J), TRFOUT, which is the amount of change in the amount of change in the period between REFs, is calculated by the following formula: TRFOUT = TREFC-TREFC _n-1 (4) where TREFC _n-1 ; .

Here, TRFOUT is the immediately preceding TREFC.
Is the amount of change in TREFC this time, and corresponds to a pseudo torque fluctuation associated with combustion.

At step K), the old value of the intermediate value LLJSUM of the engine stability index is shifted in the same manner as the shift of TREF, and at step L) the new LLJS is changed.
UM

[0029]

[Equation 1]

LLJSUM is used to calculate the engine stability index TRFSU according to step M).
M is calculated by TRFSUM = LLJSUM + LLJSUM _n-1 (6) where LLJSUM _n-1 ; LLJSUM before one time.

The number of samples DNREF in the equation (5) is determined in consideration of detection accuracy (more is better) and control speed (less is faster).

FIG. 9 is a graph for calculating the post-starting amount increase correction coefficient Kas, which is executed every predetermined time. Note that the water temperature increase correction coefficient Ktw is the same as Kas, so description thereof will be omitted.

In step A), looking at the key switch,
When the START position is switched to the ON position, it is determined that the cranking has ended (that is, immediately after the start), and the process proceeds to step B) and the post-start amount increase correction coefficient K corresponding to the heaviest fuel.
Add asH to Kas. Immediately after the start, the warm-up increase is always started with the value corresponding to the heaviest fuel.

In step C), it is determined whether the stability feedback control is permitted. The stability index TR calculated by the above equation (6) while the rotation speed rising from cranking fluctuates immediately after the engine starts.
Since the FSUM is not stable, stability feedback control is allowed when the time that TRFSUM appears to be stable has elapsed.

When the stability feedback control is permitted, in step D) the fuel injection pulse width Ti
Is compared with a predetermined value, and when Ti exceeds the predetermined value,
The flow of FIG. 9 is terminated without comparing the stability index TRFSUM with the slice level. When Ti exceeds the predetermined value, TRFSUM is good because the warm-up amount is being adjusted in accordance with acceleration, and at this time also, TRFSUM and slice level are compared,
If the value is changed to the value corresponding to the fuel on the light side, it will not be possible to correspond to the acceleration immediately after the start, so it is not desirable to switch to the value corresponding to the fuel on the light side.

The above-mentioned predetermined value is obtained from the cooling water temperature Tw by referring to the table having the characteristics shown in FIG. Since TRFSUM increases as Tw decreases (stability deteriorates), the predetermined value is also increased accordingly.

On the other hand, when Ti falls below a predetermined value,
After step E), stability feedback control is performed as in the conventional case.

In step E), the stability index TRFSUM is
Is read, and this is compared with a predetermined slice level SL2 in step F). When TRFSUM is less than SL2, it is determined that the stability is good, and the procedure proceeds to step G), where the post-starting amount increase correction coefficient KasL for the light fuel is set to Kas.
, And the flow of FIG. 9 ends. When the warm-up increase is started with the value corresponding to the heaviest fuel, the stability is improved when the fuel on the light side is used, so the mode is switched to the fuel on the light side.

Since the stability may be deteriorated again after switching to the light side fuel, TRFSUM becomes SL2 or more in the next step F), and TRFSUM becomes the predetermined slice level S in the step H).
When it becomes L1 or more, it is returned to the value corresponding to the heaviest fuel in step I). However, SL1 is set higher than SL2 as shown in FIG.

Repeating the above-mentioned steps in FIG. 7, Ka
When s and Ktw are set to correspond to acceleration after start, the stability index is good, so at the timing of t1, it is switched to Kas and Ktw for fuel on the light side, and the accelerator pedal is depressed greatly immediately after the switching. May not be able to accelerate sufficiently due to insufficient warm-up increase or may cause engine stall. In addition, since the amount of fuel supplied gradually decreases even without acceleration, the stability index increases over time.

FIG. 12 shows what happens in this example under the same conditions as in FIG. In this example as well, since the setting is for acceleration after starting, the stability index is in the good region at the timing of t1 when the stability feedback control is permitted immediately after starting, but the stability is stable because Ti exceeds the predetermined value. No comparison is made between the index and the slice level SL2. Ka for the heaviest fuel and acceleration after start
Since the operation using s and Ktw is continued, this allows sufficient fuel to be supplied according to the acceleration even when the accelerator pedal is fully depressed immediately after the start, and the setting for acceleration after start is sufficient. Be utilized by.

Further, the prohibition of the comparison between the stability index and the slice level SL2 is released at the timing when Ti coincides with the predetermined value, but at this time, the stability index moves to an appropriate region.

In the embodiment, the case where the comparison between the stability and the slice level is prohibited when the supplied fuel amount during warm-up exceeds a predetermined value has been described, but the supplied fuel amount during warm-up exceeds the predetermined value. It is also possible to prohibit the calculation of the stability when there is.

In the embodiment, the basic pulse width Tp is set to a common value irrespective of the fuel property, and the warm-up increase correction amount is set to two values, one for the heaviest fuel and one for the light fuel. As described above, the present invention is not limited to this, and regarding the fuel injection amount during warm-up (that is, Tp x warm-up increase correction amount), there are two options, one for the heaviest fuel and one for the lighter fuel. It does not matter if it is set in advance. Furthermore, it does not matter if it is not compatible with the heaviest fuel, but only compatible with the heavy fuel.

[0045]

According to the first aspect of the present invention, means for calculating the warm-up fuel amount for heavy fuel and acceleration after start-up, and the warm-up fuel amount for fuel on the lighter side than the heavy fuel are set. Calculating means, means for calculating the stability of the engine, means for comparing the calculated stability with a predetermined slice level,
Based on the result of this comparison, the warm-up fuel amount corresponding to the heavy fuel is sucked before the stability becomes lower than the slice level, and the warm-up fuel amount on the light side is sucked when the stability becomes lower than the slice level. Since the means for supplying each to the pipes and the means for prohibiting the calculation of the stability when the supplied fuel amount exceeds a predetermined value are provided, the accelerator pedal is fully filled immediately after the start when the light fuel is used. Sufficient fuel is supplied according to the acceleration even when the driver depresses the pedal, so the setting for acceleration after start is not lost.

A second aspect of the present invention calculates a warm-up fuel amount for heavy fuel and acceleration after start-up, and a warm-up fuel amount for lighter fuel than the heavy fuel. Means, a means for calculating the stability of the engine, a means for comparing the calculated stability with a predetermined slice level, and the stability for the heavy fuel before the stability becomes less than the slice level based on the comparison result. When the stability becomes less than the slice level, the means for supplying the warm side fuel amount on the light side to the intake pipe, and when the supplied fuel amount exceeds a predetermined value Since a means for prohibiting the comparison between the stability and the slice level is provided, when the accelerator pedal is fully depressed immediately after starting when using light fuel, sufficient fuel corresponding to the acceleration is supplied, and after starting acceleration Corresponding settings It is utilized to.

According to a third aspect of the present invention, in the first or second aspect, the predetermined value is set to be larger according to the engine temperature as the engine temperature decreases, so that the setting accuracy of the predetermined value is improved.

[Brief description of drawings]

FIG. 1 is a control system diagram of an embodiment.

FIG. 2 is a diagram showing a relationship between a starting injection pulse width Tist and a cooling water temperature.

FIG. 3 is a diagram showing a relationship between a water temperature increase correction coefficient Ktw and a cooling water temperature.

FIG. 4 is a diagram showing a relationship between a post-starting amount increase correction coefficient Kas and a cooling water temperature.

FIG. 5 is a characteristic diagram of a control amount Ti with respect to a time after starting.

FIG. 6 is a waveform diagram for explaining the difference between the control amount corresponding to post-start acceleration and the control amount corresponding to fast idle.

FIG. 7 is a waveform diagram for explaining the operation of the conventional device.

FIG. 8 is a flowchart for explaining calculation of a stability index TRFSUM.

FIG. 9 is a flowchart for explaining calculation of a post-start-up increase correction coefficient Ksa.

FIG. 10 is a diagram showing a relationship between a predetermined value and cooling water temperature.

FIG. 11 is a characteristic diagram of slice levels SL1 and SL2.

FIG. 12 is a waveform diagram for explaining the operation of the first embodiment.

FIG. 13 is a diagram corresponding to claims of the first invention.

FIG. 14 is a diagram corresponding to a claim of the second invention.

[Explanation of symbols]

 2 Control Unit 4 Crank Angle Sensor 6 Air Flow Meter 7 Fuel Injection Valve 11 Water Temperature Sensor 21 Warm-up Fuel Quantity Calculation Means for Heavy Fuel 22 Warm-up Fuel Quantity Calculation Means for Light Fuel 23 Stability Calculator 24 Comparison Means 25 Warm-up fuel amount supply means 26 Stability calculation prohibition means 31 Comparison prohibition means

Claims (3)

[Claims] 1. A means for calculating a warm-up fuel amount corresponding to heavy fuel and acceleration after start-up, a means for calculating a warm-up fuel amount corresponding to fuel on a lighter side than the heavy fuel, and an engine. Means for calculating the stability, and means for comparing the calculated stability with a predetermined slice level, and before the stability becomes less than the slice level based on the comparison result, during warm-up for heavy fuel. When the stability becomes less than the slice level, the means for supplying the warm side fuel amount on the light side to the intake pipe respectively, and the stability of the stability when the supplied fuel amount exceeds a predetermined value. An engine stability control device comprising means for prohibiting calculation. 2. A means for calculating a warm-up fuel quantity for heavy fuel and acceleration after start-up, a means for calculating a warm-up fuel quantity for fuel lighter than the heavy fuel, and an engine. Means for calculating the stability, and means for comparing the calculated stability with a predetermined slice level, and before the stability becomes less than the slice level based on the comparison result, during warm-up for heavy fuel. A means for supplying the warm-up fuel amount on the light side to the intake pipe when the stability becomes less than the slice level, and the stability when the supplied fuel amount exceeds a predetermined value. A stability control device for an engine, comprising: means for inhibiting comparison of slice levels. 3. The engine stability control device according to claim 1, wherein the predetermined value is set so as to increase as the engine temperature decreases in accordance with the engine temperature.