JP2571044B2 - Engine fuel supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel supply device for an engine having a fuel injection valve for supplying fuel in the latter half of an intake stroke, for example.

(Prior Art) Conventionally, as a fuel supply device for the above-described engine, there is, for example, a device described in JP-A-58-85319.

That is, the fuel injection timing is controlled for each square cylinder, and the fuel injection timing is set immediately before the end of the intake stroke of the cylinder. The stratification of the fuel to be present has an effect that efficient combustion can be ensured with a small amount of fuel.

However, in the case of the above, since fuel is supplied only immediately before the end of the intake stroke, only air exists at the lower part of the combustion chamber, and during the combustion process, that is, during the spread of flame propagation, combustion by the air is performed. Is hindered and the flammability deteriorates.

Therefore, in addition to the above-described conventional technology, by supplying a thin fuel with good vaporization to the lower part of the combustion chamber at a predetermined timing, the transmission of the flame propagation is improved, and the combustibility is secured with as little fuel as possible. Can be considered.

However, even in such a case, there are the following problems.

In other words, the above-described conventional apparatus does not include the swirl generating means, so that when the air-fuel mixture is not satisfactorily supplied in the circumferential direction of the combustion chamber, the presence of air in the peripheral portion hinders the transmission of flame propagation. However, there is a problem in that the combustion is hindered by this, and the flammability deteriorates.

(Problems to be Solved by the Invention) The present invention, in which the first fuel supply means and the second fuel supply means are provided, can stratify the air-fuel mixture and improve the fuel efficiency. By providing the swirl generating means, the swirl generating means can reliably supply a lean mixture with good vaporization and atomization in the circumferential direction of the combustion chamber, and use as thin a fuel as possible while securing the combustibility. The lean limit at which the engine rotates can be improved, and the lean mixture supplied from the second fuel supply means (lean mixture) is supplied to the vicinity of the peripheral wall of the combustion chamber, and the temperature becomes relatively low. It is an object of the present invention to provide a fuel supply device for an engine capable of improving combustion in a low peripheral wall portion and improving HC (unburned matter) as well as improving combustion stability.

(Means for Solving the Problems) According to the present invention, first fuel supply means for supplying fuel to the combustion chamber or an intake passage near the combustion chamber in the latter half of the intake stroke, and fuel is supplied by the first fuel supply means A second fuel supply means for supplying a predetermined fuel to the intake passage upstream of the location where the mixture is leaner than a mixture obtained by the fuel supplied by the first fuel supply means, and the combustion chamber And a swirl generating means for giving a swirl in the combustion chamber to the lean air-fuel mixture supplied in the combustion chamber.

(Effects of the Invention) According to the present invention, it is possible to supply a fuel having good ignitability by the first fuel supply means and a fuel having good vaporization and atomization by the second fuel supply means. A rich air-fuel mixture is supplied to the periphery of the ignition plug in the upper part of the chamber, and a lean air-fuel mixture is supplied to the lower part of the chamber to stratify, thereby improving fuel efficiency.

In addition, the above-described swirl generating means can reliably supply a lean mixture with good vaporization and atomization in the circumferential direction of the combustion chamber. There is an effect that the limit can be improved.

Moreover, since the lean air-fuel mixture supplied from the second fuel supply means can be supplied to the vicinity of the peripheral wall of the combustion chamber by swirl, the combustion on the peripheral wall having a relatively low temperature is improved, and the combustion stability is improved. There is an effect that both improvement and reduction of HC (unburned matter) can be achieved.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

The drawing shows a fuel supply device for the engine. In FIG. 1, an air flow meter 2 is connected to a purified air outlet of an air cleaner 1, and a throttle body 3 is connected to the rear of the air flow meter 2. The throttle valve 5 is provided in the throttle chamber 4 in the throttle body 3 described above.
And a throttle opening sensor 6 for detecting the opening of the above-mentioned throttle valve 5 outside the throttle body 3.
Is arranged.

The combustion chamber 7 is located at the rear of the throttle body 3.
A primary passage 8 as a swirl generating means for giving a swirl in the circumferential direction in the combustion chamber 7 to the air-fuel mixture supplied to the combustion chamber 7;
Dual induction system with secondary passage 9
The intake pipe 10 of the DIS is connected.

The primary intake port 11 and the secondary intake port 12 (see FIG. 2) corresponding to the low-load primary passage 8 and the high-load secondary passage 9 described above have intake valves 13, 13 respectively.
On the other hand, the exhaust port 14 is provided with an exhaust valve 15 to provide a cross-flow arrangement.

The cylinder head 16 having the above-described ports 11, 12, and 14 formed therein
A cylinder block 17 is attached to a lower portion of the cylinder block 17, and a piston 18 is disposed in the cylinder block 17.

Further, in the secondary passage 9 in the above-mentioned intake pipe 10, an on-off valve 20 which is opened by an actuator 19 at a high load and closed by a light load by an actuator 19 is arranged, while the above-mentioned exhaust port 14 is provided.
Is connected to an exhaust manifold 23.

In the secondary passage 9 of the intake pipe 10 serving as an intake passage near the combustion chamber 7 described above, a two-injection first fuel injection valve 21 for supplying fuel in the latter half of the intake stroke is provided.

Further, the throttle valve 5 as an intake passage on the upstream side of the location where fuel is supplied by the first fuel injection valve 21 described above.
In the throttle chamber 3 in front of the disposition position, the first
There is provided a second fuel injection valve 22 for supplying a predetermined fuel to make the mixture leaner than the mixture obtained by the fuel supplied by the fuel injection valve 21.

In this manner, the first and second fuel injection valves 21 and 22 are provided, and the first fuel injection valve 21 supplies fuel having good ignitability, and the second fuel injection valve 22 provides fuel having good vaporization and atomization. Is supplied, a mixture having a high fuel concentration is supplied to the vicinity of an ignition plug (not shown) at the upper portion of the combustion chamber, and a mixture having a low fuel concentration is supplied to the lower portion of the combustion chamber, whereby stratification can be achieved. .

By the way, the CPU 30 executes the first fuel injection valve 21 according to the program stored in the ROM 24 based on the input of the intake air amount signal, the throttle opening signal, the engine speed signal, the crank angle signal, and the cylinder discrimination signal shown in FIG. In addition, the RAM 25 drives and controls the actuators 19 for the second fuel injection valve 22 and the on-off valve 20, and the RAM 25 stores necessary data such as fuel injection start crank angle data and fuel injection end crank angle data according to load conditions.

The operation of the fuel supply device for an engine configured as described above will be described with reference to the flowchart of FIG.

In a first step 31, the CPU 30 reads various signals such as an engine speed signal, an intake air amount signal, a crank angle signal, and a cylinder discrimination signal.

Next, in a second step 32, the CPU 30 calculates the injection pulse width of the fuel injection based on the engine speed and the intake air amount.

Next, in a third step 33, the CPU 30 calculates the injection end crank angles of the fuel injection valves 21 and 22, respectively.

Next, in a fourth step 34, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the first fuel injection valve 21, that is, the crank angle corresponding to the latter half of the intake stroke.
When it has reached, the process proceeds to the next fifth step 35.

In the fifth step 35, the CPU 30 drives the first fuel injection valve 21 to inject fuel.

Next, in a sixth step 36, the CPU 30 determines whether or not the current crank angle has reached the injection start crank angle of the second fuel injection valve 22. The process moves to the seventh step 37.

In the seventh step 37, the CPU 30 determines whether or not the current crank angle has reached the fuel end crank angle of the first fuel injection valve 21, and if it has reached, shifts to the next eighth step 38. .

In the eighth step 38, the CPU 30 terminates the fuel injection by the first fuel injection valve 21.

Next, in a ninth step 39, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the second fuel injection valve 22, and if so, the next tenth step 40
Then, the CPU 30 drives the second fuel injection valve 22 to inject fuel with good vaporization and atomization.

Next, in an eleventh step 41, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22.
Then, the CPU 30 terminates the fuel injection by the second fuel injection valve 22.

The timed injection as shown in FIG. 4A is performed by the processing of steps 35 to 42.

In FIG. 4, X indicates fuel injection by the first fuel injection valve 21, and Y indicates fuel injection by the second fuel injection valve 22.

On the other hand, in the above-described sixth step 36, it is assumed that the current crank angle has reached the fuel injection start crank angle of the second fuel injection valve 22.
When the CPU 30 determines, the process proceeds to the next thirteenth step 43.

In the thirteenth step 43, the CPU 30 drives the second fuel injection valve 22 to inject fuel.

Next, in a fourteenth step 44, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22, and if so, in a next fifteenth step 45. ,
The CPU 30 terminates the fuel injection by the second fuel injection valve 22.

Next, in a sixteenth step 46, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and if so, in a next seventeenth step 47. ,
The CPU 30 terminates the fuel injection by the first fuel injection valve 21.

By the processing of the above steps 35, 36, 43 to 47, FIG.
The simultaneous injection as shown in FIG.

On the other hand, when the CPU 30 determines in the above-described fourteenth step 44 that the current crank angle has not yet reached the fuel injection end crank angle of the second fuel injection valve 22, the next eighteenth step 4
Move to 8.

In this eighteenth step 48, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and if so, in the next nineteenth step 49,
The CPU 30 terminates the fuel injection by the first fuel injection valve 21.

Next, in a twentieth step 50, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22.
Then, the CPU 30 terminates the fuel injection by the second fuel injection valve 22.

The fuel injection as shown in FIG. 4c is performed by the processing of the above steps 35, 36, 43, 44, 48 to 51.

On the other hand, when the CPU 30 determines that the current crank angle has not reached the fuel injection start crank angle of the first fuel injection valve 21 in the above-described fourth step 34, the process proceeds to the next 22nd step 52.

In this 22nd step 52, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the second fuel injection valve 22, and when it has reached, in the next 23rd step 53, the CPU 30
U30 drives the second fuel injection valve 22 to inject fuel.

Next, in a twenty-fourth step 54, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the first fuel injection valve 21, and if so, the next twenty-fifth step 55
Then, the CPU 30 drives the first fuel injection valve 21 to inject fuel.

Next, in a twenty-sixth step 56, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and if so, in the next twenty-seventh step 57. ,
The CPU 30 terminates the fuel injection by the first fuel injection valve 21.

Next, in a twenty-eighth step 58, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22. ,
The CPU 30 terminates the fuel injection by the second fuel injection valve 22.

Simultaneous injection as shown in FIG.

On the other hand, if the CPU 30 determines that the current crank angle has not reached the fuel injection end crank angle of the first fuel injection valve 21 in the above-described 26th step 56, the next 30th step 60
Move to

In this thirtieth step 60, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22.
U30 terminates the fuel injection by the second fuel injection valve 22.

Next, at step 32, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and if so, the next 33rd step 63.
Then, the CPU 30 terminates the fuel injection by the first fuel injection valve 21.

The fuel injection as shown in FIG. 4e is performed by the processing of steps 53 to 56 and 60 to 63 described above.

On the other hand, when the CPU 30 determines that the current crank angle has not reached the fuel injection start crank angle of the first fuel injection valve 21 in the aforementioned 24th step 54, the process proceeds to the next 34th step 64.

In the thirty-fourth step 64, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the second fuel injection valve 22, and if so, the next thirty-fifth step 65
Then, the CPU 30 terminates the fuel injection by the second fuel injection valve 22.

Next, in a thirty-sixth step 66, the CPU 30 determines whether or not the current crank angle has reached the fuel injection start crank angle of the first fuel injection valve 21, and if so, in the next thirty-seventh step 67 ,
The CPU 30 drives the first fuel injection valve 21 to perform fuel injection.

Next, in the aforementioned 32nd step 62, the CPU 30 determines whether or not the current crank angle has reached the fuel injection end crank angle of the first fuel injection valve 21, and if so, the next 33rd step. At 63, the CPU 30 terminates the fuel injection by the first fuel injection valve 21 as described above.

The timed injection shown in FIG. 4f is performed by the processing of the above steps 53, 54, 64 to 67, 62, 63.

At the time of fuel injection by the first and second fuel injection valves 21 and 22 described above, fuel having good ignitability is vaporized by the first fuel injection valve 21 on the downstream side, and vaporized by the second fuel injection valve 22 on the upstream side. Since fuel with good atomization is supplied, a rich air-fuel mixture is supplied around the ignition plug in the upper part of the combustion chamber, and a lean air-fuel mixture is supplied in the lower part, so that stratification can be achieved, thereby improving fuel efficiency. There is an effect that can be.

In addition, when the load is small and the opening degree of the on-off valve 20 is small, the air-fuel mixture is guided in the tangential direction of the cylinder bore by the primary passage 8 as the above-described swirl generating means, and a strong swirl S (see FIG. 2) is generated. Thus, a lean mixture with good vaporization and atomization can be reliably supplied in the circumferential direction of the combustion chamber 7, and as a result, the engine is rotated with the thinnest fuel possible while preventing misfiring and ensuring flammability. There is an effect that the lean limit can be improved.

In addition, since the lean air-fuel mixture supplied from the second fuel injection valve 22 can be supplied to an appropriate place in the combustion chamber 7 by the swirl S, that is, in the vicinity of the peripheral wall of the combustion chamber 7, the temperature is relatively low. There is an effect that it is possible to improve the combustion stability and to reduce the HC (unburned matter) at the same time by improving the combustion of the peripheral wall portion.

In the correspondence between the configuration of the present invention and the above-described embodiment, the first fuel supply means of the present invention corresponds to the first fuel injection valve 21 of the embodiment, and the intake passage in which the first fuel supply means is disposed is , Secondary passage 9
The second fuel supply means corresponds to the second fuel injection valve 22, the intake passage in which the second fuel supply means is arranged corresponds to the throttle chamber 4, and the swirl generation means corresponds to the primary passage 8 However, the present invention is not limited to only the configuration of the above-described embodiment.

For example, it goes without saying that a carburetor may be used instead of the second fuel injection valve 22.

[Brief description of the drawings]

1 is a system diagram showing a position embodiment of a fuel supply device for an engine of the present invention, FIG. 2 is a schematic plan view of a main part, FIG. 3 is a flowchart showing a fuel injection process, and FIG. It is explanatory drawing which shows an aspect. 4 throttle chamber 7 combustion chamber 8 primary passage 9 secondary passage 21 first fuel injection valve 22 second fuel injection valve

Claims (1)

(57) [Claims] 1. A combustion chamber or an intake passage near a combustion chamber,
A first fuel supply means for supplying fuel in the latter half of the intake stroke; and a fuel supplied by the first fuel supply means to an intake passage upstream of a location to which fuel is supplied by the first fuel supply means. Second fuel supply means for supplying a predetermined fuel to make the mixture leaner than the air-fuel mixture, and swirl generating means for giving the swirl in the combustion chamber a circumferential direction to the lean air-fuel mixture supplied to the combustion chamber. Engine fuel supply system equipped with.