JP2704807B2 - Engine fuel supply - 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 supply device for an engine, and more particularly to a basic fuel supply amount calculating means for determining a basic fuel supply amount to an engine from an intake pipe absolute pressure and an engine speed, and an intake pipe absolute value. An increase correction value calculating means for calculating an increase correction value of the basic fuel supply amount when it is detected from the pressure that the engine is in a high load state; and calculating the basic fuel supply amount based on an output of the increase correction value calculation means. And a fuel supply amount correcting means for correcting the output of the means.

[0002]

2. Description of the Related Art A fuel supply system for such an engine is already known, for example, from Japanese Patent Publication No. 2-45030.

[0003]

By the way, immediately after the start of the engine, the absolute pressure of the intake pipe does not immediately decrease due to the effect of the internal volume of the intake pipe including the surge tank, and the absolute pressure of the intake pipe becomes higher than it should be. May be detected. When the absolute value of the intake pipe absolute pressure is detected in this manner, the conventional fuel supply device erroneously determines that the engine is in a high load state, and the fuel supply amount is increased. In the first place, when the engine is started, the air-fuel ratio is controlled to the rich side in consideration of the poor fuel combustion state and the adhesion of the fuel to the port. And problems such as deterioration of startability and increase of harmful components in exhaust gas may occur.

The present invention has been made in view of the above circumstances, and has as its object to provide an engine fuel supply device capable of preventing the air-fuel ratio from becoming over-rich immediately after the start of the engine.

[0005]

In order to achieve the above object, the present invention determines the basic fuel supply amount to the engine from the intake pipe absolute pressure and the engine speed as shown in the claim correspondence diagram of FIG. Basic fuel supply amount calculation means, increase correction value calculation means for calculating an increase correction value of the basic fuel supply amount when it is detected that the engine is in a high load state from the intake pipe absolute pressure, and this increase correction value calculation means A fuel supply amount correcting means for correcting the output of the basic fuel supply amount calculating means based on the output of the engine, the differential pressure between the atmospheric pressure and the intake pipe absolute pressure after the engine is started.
Until the intake pipe gauge pressure, which is
Immediately after the start of the engine.
When the state immediately after the movement is determined, the increase correction value calculating means
And an increase correction prohibition unit for prohibiting an increase in the basic fuel supply amount based on the increase correction value calculated in (1) .

[0006]

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a fuel supply apparatus according to one embodiment of the present invention. Reference numeral 1 denotes an internal combustion engine of, for example, four cylinders, and an intake pipe 2 is connected to the engine 1. A throttle body 3 is provided in the middle, and a throttle valve 3 'is provided inside. A throttle valve opening (θ _TH ) sensor 4 is connected to the throttle valve 3 ′, converts the valve opening of the throttle valve 3 ′ into an electric signal and sends it to an electronic control unit (hereinafter referred to as “ECU”) 5. It has been like that.

A fuel injection valve 6 is provided in the intake pipe 2 between the engine 1 and the throttle body 3. The fuel injection valve 6 is provided for each cylinder slightly upstream of the intake valve (not shown) of the intake pipe 2 and connected to a fuel pump (not shown). The fuel injection valve 6 is electrically connected to the ECU 5, and the opening time of the fuel injection valve 6 is controlled by a signal from the ECU 5.

On the other hand, the intake pipe absolute pressure (P _B ) is located downstream of the throttle valve 3 ′ of the throttle body 3 via a pipe 7.
The intake pipe absolute pressure sensor 8 is provided with a sensor 8.
The intake pipe absolute pressure signal electrically converted by
Sent to CU5. Also, downstream of the intake air temperature (T _A )
A sensor 9 is attached. The intake air temperature sensor 9 also converts the intake air temperature into an electric signal and sends it to the ECU 5.

The engine water temperature (Tw) is stored in the engine 1 body.
A sensor 10 is provided. The engine water temperature sensor 10 is composed of a thermistor or the like, is inserted into the peripheral wall of the engine cylinder filled with cooling water, and supplies a detected water temperature signal to the ECU 5.

An engine speed (Ne) sensor 11 is mounted around a camshaft or crankshaft (not shown) of the engine 1. The engine speed sensor 11 takes in air every 180 ° rotation of the crankshaft of the engine 1. A predetermined control signal (hereinafter referred to as “TDC signal”) pulse is output to the ECU 5 at a predetermined crank angle position before the stroke start top dead center.

An exhaust pipe 13 of the engine 1 has a three-way catalyst 14
Is disposed to perform a purifying action of HC, CO, and NOx components in the exhaust gas.

Further, an atmospheric pressure (P _A ) sensor 16 and a starter switch 17 of the engine are connected to the ECU 5. The ECU 5 transmits a detection signal from the atmospheric pressure sensor 16 and an on / off state signal of the starter switch 17. Supplied.

The ECU 5 has an input circuit 5a having functions of shaping input signal waveforms from various sensors and a starter switch 17, correcting a voltage level to a predetermined level, converting an analog signal value to a digital signal value, and the like. It comprises an arithmetic processing circuit (hereinafter referred to as "CPU") 5b, a storage means 5c for storing various arithmetic programs executed by the CPU 5b and arithmetic results, an output circuit 5d for supplying a drive signal to the fuel injection valve 6, and the like. You.

Next, the contents of the control program used in the above-described apparatus will be described in detail.

FIG. 2 shows a flowchart in the case where the ECU 5 of FIG. 1 calculates the valve opening time of the fuel injection valve 6 in synchronization with the TDC signal pulse.
It is executed every time a signal pulse is generated. First, when the starter switch 17 of the engine 1 is turned on, a TDC signal pulse is input when the engine 1 is started (step 20).
1). Next, the engine water temperature Tw, the intake pipe absolute pressure P _B , the atmospheric pressure P _A , the intake air temperature T _A , the throttle valve opening θ _TH , the on / off state signal of the starter switch 17, and the like are read from each sensor, and the first TDC signal. The elapsed time from the pulse to the next TDC signal pulse is counted, and the engine speed Ne calculated based on the value is read (step 202).

Next, at step 203, the engine speed Ne is increased to a predetermined cranking speed N _CR (for example, 4
00 rpm) is determined. If the answer is negative (No), that is, if Ne ≦ N _CR holds, step 2
In step 04, it is determined whether or not the starter switch 17 is on. If the answer is affirmative (Yes), that is, if the starter switch 17 is on, the cranking state, that is, the engine 1 is being started is determined. Proceed to 205.

[0019] At step 205, reads the basic fuel injection time Ti _CR from Ti _CR table previously stored in the memory means 5c in the ECU5 based on the engine coolant temperature Tw in the cranking advance in the memory means 5c to From the stored _KNE table, the engine speed N
The fuel injection time T _OUT during the start is calculated by multiplying the engine speed correction coefficient K _NE read based on e. And Thus, actuating the fuel injection valve 6 based on the fuel injection time T _OUT in the starting (step 210).

On the other hand, if the answer at step 203 is affirmative (Y
es), that is, when Ne> _NCR is satisfied, or when the answer to step 204 is negative (No), that is, when the starter switch 1
7 to when not in the ON state, the process proceeds to step 206 to step 209 as to divorce the cranking state, calculates the fuel injection time T _OUT after starting.

That is, in step 206, the engine
Number of turns Ne and intake pipe absolute pressure P_BIn response to
Ti previously stored in the storage unit 5c_MMap to base
Main fuel injection time Ti_MIs read. Next, step 20
7, the correction coefficient K_ASTIs calculated. K_ASTIs after starting
This is a fuel increase coefficient, and_ASTCalculation subroutine
(See FIG. 3). Step 20
8, the correction coefficient K _WOTAnd correction coefficient K_TWCalculate
You. K_WOTIs the high load increase coefficient, K_TWIs the cooling water temperature increase coefficient
And these are the K_WOT, K_TWCalculation subroutine
(See FIG. 4). Step 20
In step 9, the basics read in step 206
Fuel injection time Ti_MCalculated in step 207
Post start fuel increase coefficient K_AST, Calculated in step 208
High load increase coefficient K_WOTAnd cooling water temperature increase coefficient K_TW
And the fuel injection time T after starting by the following equation:_OUTIs calculated
And then execute step 210 to determine T_OUTTo
The fuel injection valve 6 is operated based on this.

T _OUT = Ti _M × K _AST × K _WOT × K _TW × K ₁ + T ₀ (1) where K ₁ is a correction coefficient other than the above K _AST , K _WOT , and K _TW , and T ₀ is These are correction variables, all of which are set to required values based on the various engine parameter signals so as to optimize various characteristics such as fuel efficiency and exhaust gas characteristics according to the operating state of the engine.

Next, step 2 in the flowchart of FIG.
A post-start fuel increase coefficient _KAST calculation subroutine corresponding to 07 will be described with reference to FIG.

First, in step 301, it is determined whether or not the engine 1 was in a cranking state at the time of the previous loop. This determination is performed by the same method as in steps 203 and 204 in the flowchart of FIG. If the answer is affirmative (Yes), that is, if the current loop is the first TDC signal pulse generation after the engine 1 has left the cranking state, the process proceeds to step 302.

In step 302, a water temperature coefficient C _AST for calculating an initial value of the post-start fuel increase coefficient K _AST is stored in the storage means 5c in accordance with the engine water temperature Tw.
_Read from the _AST table. The engine coolant temperature Tw is determined when the last TDC signal pulse is generated during cranking. FIG. 6 shows an example of the _CAST table. Based on the figure, the engine water temperature Tw is changed to _TwAS2 (for example, -1.
0 ° C) or lower, C _AST2 (for example, 1.2) as the water temperature coefficient C _AST , and when the engine water temperature Tw is equal to or higher than Tw _AS1 (for example, + 1.0 ° C.), the water temperature coefficient C _AST becomes C _AST
AST1 (e.g. 1.0) respectively selected, if the engine coolant temperature Tw is between the Tw _AS2 and Tw _AS1 is determined by interpolation. The _CAST table can be set in various modes according to the characteristics of the engine 1 and the like.

Subsequently, using the water temperature coefficient _CAST obtained in step 302, an initial value of the post-start fuel increase coefficient _KAST is calculated based on the following equation (step 303).

K _AST = C _AST × K _TW (2) FIG. 7 shows an example of a K _TW table showing the relationship between the engine water temperature Tw and the cooling water temperature increase coefficient K _TW , wherein the engine water temperature Tw is a predetermined value Tw. K _TW when the temperature is ₅ (for example, 60 ° C) or more
It is 1.0, and K _TW for each 5-point is set for the out temperature Tw ₁ ~Tw ₅ of which is provided as the calibration variable if it becomes less than the predetermined value Tw _5, when the engine coolant temperature Tw is a value other than the variable value Tw ₁ ~Tw ₅ it is determined by interpolation.

Next, the initial value of the post-start fuel increase coefficient _KAST obtained in step 303 is set to a predetermined lower limit K
_It is determined whether it is smaller than _ASTLMT (for example, 1.2) (step 304). If the answer to step 304 is negative (No), the initial value of the post-start fuel increase coefficient K _AST obtained in step 303 is set as the initial value as it is, and the program ends. On the other hand, if the answer to step 304 is affirmative (Yes), step 30
5, the initial lower limit value of the post-start fuel increase coefficient _KAST obtained in step 303 is not used, and the predetermined lower limit value _KAST is used.
_{Set ASTLMT} as the initial value and exit this program.

The steps 302 to 305 for setting the initial value of the fuel increase described above are executed only once immediately after the end of cranking.

On the other hand, if the answer at step 301 is negative (N
o), i.e. the process proceeds to step 306 if the engine is cranking state in the last loop, after starting fuel increase coefficient K _{AS T} is a first predetermined determination value K _ASTR1 (e.g. 1.60)
It is determined whether it is greater than or equal to. This answer is affirmative (Ye
s), that is, when K _AST > K _ASTR1 holds, a first predetermined value DK _AST0 is set as a subtraction constant ΔK _AST (step 307), and the _routine proceeds to step 313. Step 30
When the answer to 6 is negative (No), that is, when K _AST ≦ K _ASTR1 is satisfied, the process proceeds to step 308, where the increase coefficient K _AST is smaller than the first predetermined determination value DK _{AST1 and} the second predetermined determination value K _ASTR0 ( For example, it is determined whether it is larger than 1.35). This answer is affirmative (Yes), that is, K _AST > K
_{When ASTR0} is satisfied, the subtraction constant ΔK is smaller than the first predetermined value DK _AST0 as _AST second predetermined value D
K _AST1 is set (step 309), and the _flow advances to step 313.

If the answer to step 308 is negative (No),
That is, when K _AST ≦ K _ASTR0 holds, step 310 is _executed.
And the intake air temperature T _A becomes equal to the predetermined determination value T _ATX (for example, 70
° C) is determined. This answer is negative (N
o), i.e. setting the subtraction constant [Delta] K _AST as the second third smaller than the predetermined value DK _AST1 predetermined value DK _AST2 when the T _A ≦ T _ATX is satisfied (step 311), positive (Yes), that is, when T _a> T _ATX is established to set the fourth predetermined value DK _AST3 greater than the third predetermined value DK _AST2 as the processing constant [Delta] K _AST (step 31
2) Then, the process proceeds to step 313.

In step 313, step 30 is executed.
7, Step 309, Step 311, Step 312
Setting the after-start fuel increase coefficient K _AST used in the previous loop to a value smaller by [Delta] K _AST by subtracting a constant [Delta] K _AST, which is set at.

Next, the routine proceeds to step 314, where it is determined whether or not the post-start fuel increase coefficient _KAST is larger than 1.0.
If the value is greater than 1.0, the program ends.

Thereafter, each time the TDC signal program is generated, the subtraction in step 313 is repeatedly executed, so that the post-start fuel increase coefficient K _AST is, for example, the solid lines A, B and C shown in FIG. 'Along the middle polygonal line. That is, an initial value of the post-start fuel increase coefficient K _AST is set in accordance with the engine coolant temperature Tw immediately before the end of cranking, and thereafter, when the value is larger than the first predetermined determination value K _{ASTR1, the} degree of decrease is large. is reduced (solid line a in FIG. 8), smaller than該判specific value K _ASTR1, and is reduced with a small degree of decrease in the case greater than the second predetermined determination value K _ASTR0 (solid line B in FIG. 8), further K _{When the AST} becomes smaller than the discrimination value K _ASTR0 , the intake air temperature T _A at that time is decreased with a smaller degree at a low temperature lower than the predetermined discrimination value T _ATX (solid line C in FIG. 8), and the intake air temperature T _A There is reduced by greater decrease level than this when the very high temperatures greater than the determination value T _{aT X} (broken line in FIG. 8 C ').

Therefore, in the present embodiment, the degree of decrease in the post-start fuel increase coefficient K _AST when it is equal to or less than the predetermined discrimination value is set in accordance with the intake air temperature T _A , so that the post-start fuel increase period is the engine increase time. When the engine 1 is in a very high temperature state and bubbles are generated in the fuel in the fuel injection valve 6, it is long when the fuel cell 1 is in a low temperature state and no bubbles are generated in the fuel of the fuel injection valve 6. Is set to be short, so that operability after starting can be ensured irrespective of the temperature of the engine 1.

If the subtraction in step 313 is repeatedly executed and the post-start fuel increase coefficient _KAST becomes a value of 1.0 or less, the answer in step 314 becomes negative (No), and the post-start fuel increase period ends. The increase coefficient K _AST is set to 1.0 (step 315), and the program ends.

Next, step 2 in the flowchart of FIG.
The high-load increase coefficient K _{WO T} and the cooling water temperature increase coefficient K _TW calculation subroutine corresponding to 08 will be described with reference to FIG.

First, at step 401, a cooling water temperature increase coefficient K _TW is calculated. This cooling water temperature increase coefficient K _TW is
In the same manner as in step 303 in the flowchart of FIG. 3 described above, it is obtained from the K _TW table showing the relationship between the engine water temperature Tw and the cooling water temperature increase coefficient K _TW .

Subsequently, in step 402, it is determined whether or not the intake pipe absolute pressure P _B is _{equal to} or higher than a predetermined determination value P _BWOT . As shown in FIG. 9, the discrimination value P _BWOT is a variable that depends on the engine speed Ne. When the intake pipe absolute pressure P _B is in the shaded region, the determination value P _BWOT is _changed to a high load state where P _B ≧ P _BWOT holds. When it is determined that the pressure is present, the process proceeds to step 403. If the absolute value of the intake pipe absolute pressure P _B is in a region other than the diagonal line, P _B <P _BWOT
Is determined to be in the low load state where
Proceed to 6.

The answer at step 402 is affirmative (Ye).
s), that is, when the load is high, it is determined in next step 404 whether the flag F _ENKWOT is “1” or “0”. The flag F _ENKWOT is for determining whether the engine 1 has entered a steady operation state or has just been started. That is, immediately after the start of the engine 1,
Due to the internal volume of the intake pipe 2 including the surge tank, the intake pipe absolute pressure P _B does not immediately decrease and a response delay occurs. As a result, the intake pipe absolute pressure P output by the intake pipe absolute pressure sensor 8 is output.
There is a case where _B becomes high and it is erroneously determined that the engine 1 is in a high load state. Therefore, when the engine 1 is in a state immediately after the start, the flag F _ENKWOT is set to “0” for identification.

In step 403, the flag F _ENKWOT
Is set to “1”, the step 404
The predetermined value K at which the high load increase coefficient K _WOT is greater than 1.0
_WOT1 is _set, and the fuel supply amount is increased at the time of actual high load. On the other hand, if the flag F _ENKWOT is set to “0” in step 403, the high load increase coefficient K _WOT is set to 1.0 in step 405. As a result, the increase in the fuel supply amount at the time of the apparent high load immediately after the start of the engine 1 is regulated, and the inconvenience that the air-fuel efficiency becomes overrich, the startability is reduced, and the exhaust gas and harmful substances are increased. To be avoided.

Next, how the flag F _ENKWOT is set will be described with reference to the flowchart of FIG.

In step 501, when the engine 1 is stopped, the flag F _{EN KWOT} is set to "0" (step 502). After the engine 1 is started, the atmospheric pressure P _A and the intake pipe gauge pressure P _BRAM a differential pressure between the intake pipe absolute pressure P _B output from the intake pipe absolute pressure sensor 8 for outputting the atmospheric pressure sensor 16 (= P _A −P _B ) is compared with a predetermined determination value DP _BKWT (for example, 200 _mmHg ) (step 503). If the intake pipe absolute pressure P _B does not immediately decrease due to a response delay immediately after the start of the engine 1,
Intake pipe gauge pressure P _BRAM decreases and P _BRAM <DP _BKWT
Holds , and the flag F _ENKWOT remains set to “0”. On the other hand, if the intake pipe absolute pressure P _B is sufficiently decreased after a predetermined time has elapsed immediately after the start of the engine 1, the intake pipe gauge pressure P _BRAM increases, and P _BRAM ≧ DP _BKWT holds.
The flag F _ENKWOT is set to "1" (step 50).
4). In this way, it is determined from the flag F _ENKWOT whether or not the engine 1 is in a state immediately after starting. Also, once the flag F _ENKWOT is set to "1",
Even if the throttle valve 3 'is opened and the intake pipe gauge pressure P _{BRAM falls} below the discrimination value DP _BKWT , the flag F _ENKWOT remains set to "1", so that a high load increase is permitted.

Returning to FIG. 4, on the other hand, if the answer to step 402 is negative (No), that is, if the vehicle is in a low load state, then in step 406, the throttle valve opening θ _TH is set to a predetermined discrimination value θ
_It is determined whether it is ₀ or more. If the answer is affirmative (Yes), 1.0 is obtained from the K _WOT table showing the relationship between the throttle valve opening θ _TH and the high load increase coefficient K _WOT shown in FIG. Then, a high load increase coefficient K _WOT larger than is calculated (step 407). On the other hand, if the answer to the question of the step 406 if it is negative (No), the high-load increase coefficient K _{WO T} is set to 1.0.

After the cooling water temperature increase coefficient K _TW is calculated in step 401 as described above, and the high load increase coefficient K _WOT is determined in steps 404, 405, 407, and 408, the process _proceeds to step 409. It is determined whether the cooling water temperature increase coefficient K _TW is larger than the high load increase coefficient K _WOT . If the answer to step 409 is affirmative (Yes) and K _TW > K _WOT holds,
In step 410, the smaller high load increase coefficient K
_{If WOT} is set to 1.0 and conversely the answer at step 409 is negative (No) and K _TW ≦ K _WOT holds,
In step 411, the smaller cooling water temperature increase coefficient K
_TW is set to 1.0.

That is, by using the larger increase coefficient without using the smaller increase coefficient of the cooling water temperature increase coefficient K _TW and the high load increase coefficient K _WOT , the fuel supply amount to the engine 1 becomes excessive. Is prevented.

In this manner, the fuel increase coefficient K _AST , the cooling water temperature increase coefficient K _TW, and the high load increase coefficient K after the start are obtained.
_{When WOT} is calculated, as described above, in step 209 of the flowchart of FIG. 2, the fuel after starting is calculated based on the above equation (1) T _OUT = Ti _M × K _AST × K _WOT × K _TW × K ₁ + T _0. The injection time T _OUT is calculated, and the fuel injection valve 6 is finally operated in step 210 based on the fuel injection time T _OUT .

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various small design changes can be made.

[0049]

[0050]

According to the onset bright as the foregoing, since the engine is prohibited high-load increase amount of the basic fuel supply quantity to determine that it is in a state immediately after start-up, the influence of the intake pipe volume Immediately after the start, the engine is erroneously determined to be in the high load state, and unnecessary high load increase is reliably prevented. As a result, the air-fuel ratio is prevented from extremely shifting to the rich side, and it is possible to avoid deterioration of the startability and increase of harmful components in the exhaust gas. Also start of the engine
Intake pipe game which is the differential pressure between atmospheric pressure and intake pipe absolute pressure after operation
Start the engine until the pressure drops below the specified value.
It is determined that the engine has just started running, so the engine is started.
The state immediately after can be accurately determined.

[0051]

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel supply device according to an embodiment of the present invention.

FIG. 2 is a flowchart of a main routine for determining a fuel injection amount.

FIG. 3 is a flowchart of a subroutine for determining a post-start fuel increase coefficient;

FIG. 4 is a flowchart of a subroutine for determining a high load increase coefficient and a cooling water temperature increase coefficient;

FIG. 5 is a flowchart of a subroutine for setting a flag for determining a state immediately after starting;

Figure 6 is a graph showing the relationship between Tw and C _AST

FIG. 7 is a graph showing the relationship between Tw and K _TW .

FIG. 8 is a graph showing the relationship between the number of TDC signal pulse occurrences and _KAST.

FIG. 9 is a graph showing the relationship between Ne and P _B

FIG. 10 is a graph showing the relationship between θ _TH and K _WOT.

FIG. 11 is a diagram corresponding to claims.

[Explanation of symbols]

M ₁ Basic fuel supply amount calculation means M ₂ Correction value calculation means M ₃ Fuel supply amount correction means M ₄ Immediately after start determination means M ₅ Increase correction inhibition means K _WOT Increase correction value Ne Engine speed _{PA A} atmospheric pressure P _B intake pipe Absolute pressure P _BRAM intake pipe gauge pressure Ti _M basic fuel supply

Claims (1)

(57) [Claims] 1. A basic fuel supply amount calculating means (M ₁ ) for determining a basic fuel supply amount (Ti _M ) to an engine from an intake pipe absolute pressure (P _B ) and an engine speed (Ne); An increase correction value calculation means (M ₂ ) for calculating an increase correction value (K _WOT ) of the basic fuel supply amount (Ti _M ) when it is detected from the pressure (P _B ) that the engine is in a high load state;
A fuel supply device for an engine and a fuel supply amount correcting means for correcting (M ₃₎ an output of said basic fuel supply amount calculating means (M ₁₎ on the basis of the output of the increase correction value calculating means (M ₂₎ , After starting the engine, the atmospheric pressure (P _A ) and the intake pipe absolute pressure (P
_B ) The intake pipe gauge pressure (P _BRAM ), which is the differential pressure from
The period until it drops below
And immediately after the start discriminating means for discriminating a certain (M _4), a state immediately after the start of the engine by just the start determination means (M ₄₎
When it is determined, the increase correction value calculating means (M ₂ ) calculates
Basic fuel supply based on the increased correction value (K _WOT )
Means for prohibiting increase correction (M ₅ ) for prohibiting increase of (Ti _M )
A fuel supply device for an engine, comprising: