JPH06129281A - Fuel feeding device of engine - Google Patents

Abstract

PURPOSE:To improve ignitability at the time of returning from deceleration fuel cut, to prevent over-rich of an actual air-fuel ratio thereafter, to improve emission and to prevent thermal shock of a catalyser by reducing fuel for a specified period of time after increasing fuel at the time of returning from the deceleration fuel cut. CONSTITUTION:It is furnished with a first judgement means P1 to judge time not requiring torque at the time of engine deceleration, a fuel cutting means P2 to carry out fuel cutting at the time not requiring torque in accordance with a judgement result of the first judgement means P1 and a second judgement means P4 to judge whether it is time to return from the fuel cutting or not. It is a fuel feeding device of an engine also furnished with a fuel increase means P5 to increase fuel for specified period of time more than a fundamental fuel injection amount at the time of returning from the fuel cutting in accordance with a judgement result of the second judgement means P4. Additionally, a third judgement means P6 to judge whether fuel increase by the fuel increase means P5 is finished or not and a fuel reduction means P7 to reduce fuel for a specified period of time less than the fundamental fuel injection amount after fuel increase if finished in accordance with a judgement result of the third judgement means P6.

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, for example, which increases the amount of fuel for a predetermined time when returning from deceleration fuel cut.

[0002]

2. Description of the Related Art Generally, when the engine speed is equal to or higher than a predetermined speed and the throttle valve opening is substantially closed or fully decelerated (when no output is required), fuel efficiency is improved, misfire is prevented, and an exhaust system is used. After that, fuel cut is executed for the purpose of preventing afterburn and temperature rise of exhaust system. Then, at the time of returning from this fuel cut, JP-A-57-12403
As disclosed in Japanese Patent Publication No. 3, a means for increasing the amount of fuel for a predetermined time from the basic fuel injection amount is adopted.

That is, at the time of fuel cut, all the fuel adhering to the wall surface of the intake pipe (the amount adhering to the pipe surface, the amount adhering to the wall surface, the amount of intake manifold) is carried away into the combustion chamber,
Since the amount of adhering to the pipe surface becomes zero or almost zero, when returning from the fuel cut, the fuel that has been injected from the injector begins to adhere to the wall surface of the intake pipe, and the amount of direct injection (the amount that directly enters the combustion chamber) is this much. Since the amount decreases, the amount should be increased in proportion to this amount of adhesion.

Further, at the time of fuel cut, there is no fuel in the fuel chamber and there is no flame, so the temperature of the combustion chamber wall is lowered, and due to this temperature drop, the vaporization and atomization of the fuel are in a bad state, so the fuel When returning from the cut, the dose is increased to compensate for this deterioration.

As described above, in the conventional fuel supply system for an engine, the fuel amount is increased from the basic fuel injection amount for a predetermined time (the amount corresponding to the above-mentioned adhered amount and the deteriorated amount) at the time of returning from the deceleration fuel cut. In order to improve restartability, prevent misfires, and prevent engine stop, this increase in fuel causes an excessive amount of adhering to the pipe surface, which causes so-called lagging that flows into the combustion chamber during subsequent operation. , The actual air-fuel ratio becomes overrich, and the emission deteriorates. In addition, unburned components in the combustion chamber are reburned (afterburned) in the catalyst of the catalytic converter provided in the exhaust system due to overrich, which causes a problem of so-called thermal shock that deteriorates the catalyst. It was

[0006]

SUMMARY OF THE INVENTION The invention according to claim 1 of the present invention ignitability at the time of returning from the deceleration fuel cut by reducing the fuel for a predetermined time after increasing the amount of fuel at the time of return from the deceleration fuel cut. Of course,
An object of the present invention is to provide an engine fuel supply device capable of preventing the subsequent over-riching of the actual air-fuel ratio and achieving the improvement of emission and the prevention of thermal shock of the catalyst.

According to the second aspect of the present invention, in addition to the object of the first aspect of the invention, by appropriately reducing the amount of fuel, it is possible to surely prevent overrich and over lean of the actual air-fuel ratio. It is an object of the present invention to provide a fuel supply device for an engine capable of achieving the above.

[0008]

According to a first aspect of the present invention, there is provided first determining means for determining when torque is not needed during engine deceleration, and when torque is not needed based on the determination result of the first determining means. Fuel cut means for executing fuel cut; second judgment means for judging whether or not it is time to return from fuel cut; and based on the judgment result of the second judgment means, from the basic fuel injection amount at the time of return from fuel cut A fuel supply device for an engine, comprising: a fuel increasing means for increasing the amount of fuel for a predetermined time; a third judging means for judging whether or not the fuel increasing by the fuel increasing means is finished, and a third judging means. A fuel supply device for an engine, comprising: a fuel reducing means for reducing the fuel amount from the basic fuel injection amount for a predetermined time after the fuel amount increase is completed based on the determination result.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the fuel reduction time by the fuel reduction means depends on a parameter related to the amount of fuel adhering to the pipe surface. It is characterized in that it is an engine fuel supply device to be set.

[0010]

According to the invention described in claim 1 of the present invention, as shown in the claim correspondence diagram of FIG. 6, when the first determining means P1 determines that the torque during deceleration of the engine is unnecessary. The fuel cut means P2 executes fuel cut for the injector P3. When the second determination means P4 determines that it is time to return from the fuel cut, the fuel amount increase means P5 causes the injector P3 to increase the fuel amount for a predetermined time from the basic fuel injection amount. Further, when the third determination means P6 determines that the fuel amount increase by the fuel amount increase means P5 is finished, the fuel amount decrease means P
Reference numeral 7 executes a fuel reduction for the injector P3 by reducing the fuel from the basic fuel injection amount for a predetermined time.

In this way, since the fuel is reduced for a predetermined time after the fuel is increased when returning from the deceleration fuel cut, the ignitability at the time of returning from the deceleration fuel cut can be improved and, of course, the so-called thereafter. There is an effect that it is possible to prevent the actual air-fuel ratio from being overriched by the lag and to improve the emission and prevent the thermal shock of the catalyst.

According to the invention of claim 2 of the present invention,
In addition to the effect of the invention described in claim 1, the fuel reduction time by the fuel reduction means is a parameter related to the amount of fuel adhering to the pipe surface (so-called in-maniwet amount) (for example, combustion chamber wall temperature is detected instead. Since it is set according to the engine water temperature, the fuel cut time, etc., it is possible to appropriately reduce the amount of fuel. As a result, there is an effect that it is possible to surely prevent overrich and over lean of the actual air-fuel ratio.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The drawing shows a fuel supply system for an engine. In FIG. 1, an air flow sensor 3 is connected to the rear of an element 2 of an air cleaner 1 for purifying intake air, and the air flow sensor 3 is configured to detect an intake air amount Q. ing.

A throttle body 4 is connected to the rear of the air flow sensor 3 described above, and a throttle chamber 6 in the throttle body 4 is provided with a throttle valve 6 for controlling the amount of intake air. And this throttle valve 6
A surge tank 7 as an expansion chamber having a predetermined capacity is connected to the downstream intake passage, an intake manifold 9 communicating with the intake port 8 is connected downstream of the surge tank 7, and an injector 10 is connected to the intake manifold 9. Are installed.

On the other hand, the intake port 8 and the exhaust port 13 which are in proper communication with the combustion chamber 12 of the engine 11 are
Intake valve 14 which is opened and closed by a valve mechanism (not shown)
The exhaust valve 15 and the exhaust valve 15 are attached to the cylinder head, and an ignition plug (not shown) having a spark gap facing the combustion chamber 12 is attached to the cylinder head.

An O 2 sensor 17 as an air-fuel ratio sensor is provided in an exhaust passage 16 communicating with the above-mentioned exhaust port 13, and a catalytic converter 18 so-called catalyst for detoxifying harmful gas is provided at the rear of the exhaust passage 16. Are connected.

Further, a bypass passage 19 for bypassing the above-mentioned throttle valve 6 is provided, and an ISC valve 20 as an ISC (idle speed control) mechanism is provided in the bypass passage 19 while the air cleaner 1 is provided on the downstream side of the element 2. An intake air temperature sensor 21 is provided in the throttle body 4, a throttle sensor 22 is provided in the throttle body 4, and a water temperature sensor 23 for detecting the combustion chamber wall temperature is provided in the water jacket. Further, a boost sensor 24 for detecting the intake negative pressure is attached to the surge tank 7.

FIG. 2 shows a control circuit of the fuel supply device, which is C
The PU 30 has an intake air amount Q from the air flow sensor 3, a throttle opening TVO from the throttle sensor 22, an intake negative pressure B from the boost sensor 24, an engine water temperature tw from the water temperature sensor 23, and an engine speed Ne from the distributor 25. Based on various necessary signal inputs such as, according to a program stored in the ROM 26, drive control of the injector 10 and the pipe surface adhesion correction timer 27,
Further, the RAM 28 has a map shown in FIG. 3, a pipe surface attachment correction timer table value A (see FIG. 4), a pipe surface attachment correction amount table value TGCKAN (see FIG. 4), and a back droop reduction correction amount table value TGCATO (see FIG. 4). ) Stores necessary data such as a table corresponding to each of the above).

The map shown in FIG. 3 is a map in which the horizontal axis represents the engine speed Ne and the vertical axis represents the engine load CE, and the F / C zone for executing the deceleration fuel cut is set.

Here, the CPU 30 described above is based on the first determination means (see the second step S2 in the flowchart of FIG. 4) for determining the time when torque is not needed during engine deceleration and the determination result of the first determination means. Fuel cut means that executes fuel cut when torque is not needed (see third step S3 in the flowchart of FIG. 4) and second determination means that determines whether or not it is time to return from fuel cut (fifth step in the flowchart of FIG. 4) S5) and the second
Fuel increasing means (see sixth and seventh steps S6 and S7 in the flowchart of FIG. 4) for increasing the fuel for a predetermined time from the basic fuel injection amount when returning from the fuel cut based on the judgment result of the judging means, and the fuel increasing amount. Third determination means for determining whether or not the fuel amount increase by the means has ended (see thirteenth step S13 in the flowchart of FIG. 4),
It also serves as fuel reducing means (see fifteenth step S15 in FIG. 4) for reducing the fuel amount from the basic fuel injection amount for a predetermined time after the fuel amount increase is completed based on the determination result of the third determining means.

Further, the fuel reduction time by the above-mentioned fuel reduction means is the amount of fuel adhered to the pipe surface (specifically, the area of the rectangular portion shown by hatching the time chart shown in FIG. 5).
Set according to the parameters related to.

The operation of the fuel supply system for the engine thus constructed will be described in detail below with reference to the flow chart shown in FIG. 4 and the time chart shown in FIG. In addition,
The contents of various reference symbols used in the following description are as follows.

TP ... Final injection pulse width of fuel TE1 ... Basic fuel injection amount TM ... Correction time by tube surface adhesion correction timer 27 (see FIG. 5) A ... Table value for setting correction time TM by tube surface adhesion correction timer 27 CKAN ... Pipe surface adhesion correction amount (see FIG. 5) TGCKAN ... Table value for determining the pipe surface adhesion correction amount CKAN (in this embodiment, a CKAN correction table based on the rotation drop speed is used.) CATO ... Back droop reduction correction amount (Refer to FIG. 5) TGCATO ... Table value for determining the backward droop reduction correction amount CATO α ... Decrement value of the backward droop reduction correction amount (time t in FIG. 5)
2 corresponds to the slope of the straight line between t3, but α> 0) In the first step S1, the CPU 30 causes the engine speed Ne from the distributor 25, the negative intake pressure B from the boost sensor 24, and the throttle opening from the throttle sensor 22. Once TVO is read, CE = Q / N
The engine load CE is calculated based on the arithmetic expression of e.

Next, in a second step S2, the CPU 30 determines the engine speed Ne and the engine load CE as described above.
It is determined whether or not the current engine operating condition is the F / C zone of the map shown in FIG. 3, and if it is the F / C zone, the next third
On the other hand, if the zone is another zone, the process proceeds to another fourth step S4.

In the above-mentioned third step S3, the CPU 30 sets the final fuel injection pulse width TP to zero, and then executes the first
0 the step S10, and the tenth step S10
Then, the CPU 30 drives the injector 10 with the final injection pulse width TP. In this case, since TP = 0, deceleration fuel cut (so-called fuel cut) is executed.

On the other hand, in the above-mentioned fourth step S4, the CPU
Reference numeral 30 calculates the basic fuel injection amount TE1 based on the calculation formula TE1 = (Q / Ne) × K.

Here, Q is the intake air amount Ne is the engine speed K is a constant.

Next, in a fifth step S5, the CPU 30 determines from the throttle opening TVO from the throttle sensor 22 whether or not it is the moment of returning from the deceleration fuel cut (time t1 in the timing chart of FIG. 5). The process proceeds to the next sixth step S6, and if NO is determined, the process proceeds to another eleventh step S11.

In the above-described sixth step S6, the CPU 30 sets the correction time TM (see FIG. 5) by the tube surface adhesion correction timer 27 to the table value A, and at the same time, the timer 27.
The CPU 30 sets the tube surface attachment correction amount CKAN to the table value TGCKAN in the following seventh step S7. Here, each table value A (TGCKAN) described above is determined corresponding to the engine water temperature tw, the engine speed Ne, and the fuel cut time.

Next, in an eighth step S8, the CPU 30 sets the back droop reduction correction CATO to zero and executes so-called initialization. Next, in a ninth step S9, the CPU 30 causes TP =
The fuel final injection pulse width TP is calculated based on the arithmetic expression of TE1 × (1 + CKAN−CATO), and in the next tenth step S10, the CPU 30 determines the final injection pulse width TP.
Since the injector 10 is driven at, the fuel is increased from the basic fuel injection amount TE1 when returning from the deceleration fuel cut (see time t1) as shown in the time chart of FIG. The fuel amount increase control is performed by the pipe surface adhesion correction timer 2
7 is executed until the time is up (from time t1 to time t2 in the time chart of FIG. 5).

On the other hand, in the above eleventh step S11, C
The PU 30 determines whether or not the tube surface adhesion correction timer 27 is counting (whether the time t1 in FIG. 5 has passed and the time t2 has elapsed). If YES, the process proceeds to the twelfth step S12, and NO At the time of determination, the process proceeds to another 18th step S18.

In the twelfth step S12 described above, the CPU 3
0 executes the countdown, and the next thirteenth step S1
In 3, the CPU 30 determines whether or not the correction time TM has become zero (whether or not the time point t2 in the time chart of FIG. 5 has been reached). When the time point t2 has been reached, the process proceeds to the 14th step S14. On the other hand, when the time t1 has passed and the time t2 has not yet been reached, the process proceeds to another 16th step S16.

In the above 16th step S16, the CPU 3
0 is for the purpose of making the amount of fuel increase at the time of recovery from deceleration fuel cut constant, and this time the pipe surface adhesion correction amount CKAN
(i) is set to a value equal to the previous pipe surface adhesion correction amount CKAN (i-1). Note that this CKAN (i) = CKAN (i-1)
The correction amount CKAN may be decremented (gradually reduced) in place of the process (1), or CKAN may be changed according to a table value.

Next, in a seventeenth step S17, the CPU 30
Is the back droop reduction correction amount CAT corresponding to the fuel increase control
Hold O to zero. After that, since the process proceeds to the ninth and tenth steps S9 and S10, the fuel consumption is changed from time t1 to time t2 in the time chart of FIG. 5, that is, until the pipe surface adhesion correction timer 27 times up. Increase control is executed.

On the other hand, in the above thirteenth step S13, TM
When the fuel amount increase is determined to be = 0 (time t2 is reached), the process proceeds to the 14th step S14. This 14th
In step S14, the CPU 30 sets the tube surface adhesion correction amount CKAN to zero in response to the end of the fuel increase, and in the next fifteenth step S15, the CPU 30 sets the back droop reduction correction amount CAT.
Set O (see FIG. 5) to the table value TGCATO.
This table value TGCATO and decrement value α
(Slope of a straight line between time points t2 and t3) is determined corresponding to the area of the rectangular portion shown by hatching in the time chart shown in FIG. 5, that is, CKAN × TM.

Next, the above-mentioned ninth and tenth steps S9,
Since the process proceeds to S10, at the time t2, as shown in FIG. 5, from the basic fuel injection amount TE1, the backward sag correction amount CA
The fuel amount reduction control with the TO amount reduced is executed.

On the other hand, in the above-mentioned eighteenth step S18, C
Whether the PU 30 is the back droop reduction correction amount CATO ≠ 0 (see FIG. 5)
Whether or not the time point t3 has not reached), and the CATO
When NO is determined as = 0 (when the time point t3 in FIG. 5 is reached), the process proceeds to the ninth step S9 described above, and YES when CATO ≠ 0.
Upon determination, the process proceeds to the next 19th step S19.

In this 19th step S19, the CPU 30
Is the deceleration amount correction amount CATO of this time by subtracting the decrement value α from the previous drooping amount reduction correction amount CATO (i-1).
The so-called decrement process (i) is executed. Therefore, between the time t2 and the time t3 in FIG. 5, the back droop reduction correction amount CATO is gradually reduced, and finally CATO = 0.
Becomes

That is, from time t2 to time t3 shown in FIG.
The fuel amount reduction correction corresponding to the area of the triangular portion is performed by hatching up to.

In summary, when the first determining means (see the second step S2) determines that the torque is not needed during engine deceleration, the fuel cut means (see the third step S3) cuts the fuel to the injector 10. Run. When the second determination means (see fifth step S5) determines that it is time to return from the fuel cut, the fuel increase means (see sixth and seventh steps S6 and S7) causes the injector 10 to receive the basic fuel. The fuel amount increase is executed to increase the fuel amount from the injection amount TE1 for a predetermined time. Further, when the third determination means (see thirteenth step S13) determines that the fuel amount increase by the fuel increase means described above is completed, the fuel reduction means (see fifteenth step S15) causes the injector 1 to operate.
For 0, the fuel reduction is performed by reducing the fuel from the basic fuel injection amount TE1 for a predetermined time.

As described above, since the fuel is reduced for a predetermined time after the fuel is increased at the time of returning from the deceleration fuel cut, the ignitability can be improved at the time of returning from the deceleration fuel cut and at the time of the subsequent operation. In the above, it is possible to prevent the actual air-fuel ratio from becoming overrich due to so-called lagging that occurs due to the excessive amount of adhesion on the pipe surface, and it is possible to achieve the effect of improving emission and preventing thermal shock of the catalyst. is there.

In addition, the fuel reducing time by the above-mentioned fuel reducing means (see fifteenth step S15) (specifically, FIG.
The time from the time point t2 to the time point t3 in the time chart is set according to the parameter related to the amount of fuel adhering to the pipe surface, so that appropriate fuel reduction can be performed, and as a result, the actual air-fuel ratio There is an effect that it is possible to surely prevent overrich and over lean.

In the correspondence between the configuration of the present invention and the above-described embodiment, the first determining means of the present invention is the CPU 3 of the embodiment.
Corresponding to the second step S2 by the 0 control, and the like below,
The fuel cut means corresponds to the third step S3 controlled by the CPU 30, the second determination means corresponds to the fifth step S5 controlled by the CPU 30, and the fuel amount increase means corresponds to the CPU 3
Corresponding to the sixth and seventh steps S6 and S7 under the 0 control, the third judging means is the thirteenth under the control of the CPU 30.
Corresponding to step S13, the fuel reducing means is the CPU 30.
Although it corresponds to the fifteenth step S15 by control, the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

FIG. 1 is a system diagram showing a fuel supply device for an engine of the present invention.

FIG. 2 is a control circuit block diagram of the fuel supply device.

FIG. 3 is an explanatory diagram of a map in which an F / C zone is set.

FIG. 4 is a flowchart showing fuel control.

FIG. 5 is a time chart showing fuel control.

FIG. 6 is a diagram for responding to a complaint.

[Explanation of symbols]

 S2 ... First determining means S3 ... Fuel cutting means S5 ... Second determining means S6, S7 ... Fuel increasing means S13 ... Third determining means S15 ... Fuel reducing means

Claims (2)

[Claims] 1. A first determining means for determining when torque is not needed during engine deceleration, a fuel cut means for executing a fuel cut when torque is not needed based on the determination result of the first determining means, and a return from fuel cut. Of the engine including a second determining means for determining whether it is time and a fuel increasing means for increasing the fuel for a predetermined time from the basic fuel injection amount when returning from the fuel cut based on the determination result of the second determining means. In the fuel supply device, a third determination means for determining whether or not the fuel amount increase by the fuel amount increase means is finished, and a predetermined amount from the basic fuel injection amount after the fuel amount increase is finished based on the determination result of the third determination means. A fuel supply device for an engine, comprising: a fuel reduction means for reducing the amount of fuel per hour. 2. The fuel reduction time by the fuel reduction means is:
The fuel supply device for an engine according to claim 1, wherein the fuel supply device is set according to a parameter relating to the amount of fuel adhering to the pipe surface.