JPS6030418A - Stratiform charging engine - Google Patents

Abstract

PURPOSE:To actively atomize and vaporize fuel and improve ignitability of an engine by injecting fuel and air against the spark plug in a combustion chamber by the control of a fuel injection valve and an air injection valve in a prescribed time from the latter half of a suction stroke to the compression stroke at a light load of the engine. CONSTITUTION:A primary and a secondary passages 8, 9 are provided in the combustion chamber 7 of each cylinder and a swirl control valve 10 which is controlled through an actuator 11 is provided in the passage 9. A fuel injection valve 21 is arranged to face a spark plug 20 and an air injection valve 22 is arranged in such a direction that the injected air is mingled with the injected fuel. When the engine load is light, at a prescribed time in the latter half of a compression stroke, fuel is injected against the spark plug 20 from the injection valve 21 to supply fuel mainly to the vicinity of the spark plug 20, which facilitates the ignition and combustion even the fuel quantity is small. In addition, air is injected at this time from the injection valve 22 to be mingled with the injected fuel, which allows efficient atomization and vaporization of the fuel in a short time and improves ignitability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a stratified air charge engine that directs fuel towards a spark plug of the engine.

(Prior art) In conventional general spark ignition engines (gasoline engines), the amount of intake air is adjusted using a throttle valve, and the amount of fuel is supplied in accordance with the amount of intake air to mix it uniformly with the air. The combustion chamber is ignited by a spark plug.

As a means to improve the output and fuel efficiency of such an engine, for example, as seen in Japanese Utility Model Application Publication No. 54-56006, compressed air is supplied into the combustion chamber during the compression stroke to promote swirling flow, thereby increasing the combustion speed. There are some known products that increase the

By the way, at least when the engine is under low load, if there is an air-fuel mixture with an ignitable air-fuel ratio near the spark plug, sufficient combustion will be possible even if the fuel is lean in other parts of the combustion chamber, and the engine will start. can be activated. Focusing on this point, as a means to significantly improve fuel efficiency, as shown in Japanese Patent Application Laid-Open No. 49-62807,
2. Description of the Related Art A so-called stratified air supply engine is known in which fuel is injected into a spark plug by its own weight at a predetermined timing corresponding to the ignition timing. According to this engine, lean combustion is possible as long as fuel that provides the required air-fuel ratio is supplied near the spark plug, and since there is no problem even if excessive air is supplied, the opening of the throttle valve can be controlled at low loads. A large comb or a throttle valve can be omitted, thereby reducing pumping loss at low loads. As a result, it is possible to significantly improve fuel efficiency.

In stratified air-charged engines in which °C fuel is injected toward the spark plug in this way, at low loads, in order to improve ignition performance,
It is desired to promote atomization and vaporization of the fuel as much as possible.

(Object of the Invention) In view of the above circumstances, the present invention provides a stratified air supply engine that injects fuel towards a spark plug at a predetermined timing at least during low load, by actively atomizing the fuel, The purpose is to vaporize and improve ignitability.

(Structure of the Invention) The stratified air supply engine of the present invention includes a fuel injection valve disposed facing the spark plug of the engine, an air injection valve that mixes air into the injected fuel from the fuel injection valve, and an air injection valve that mixes air into the injected fuel from the fuel injection valve. A load detection means for detecting the load state, a crank angle detection means for detecting the crank angle of the engine, and receiving the outputs of the load detection means and the crank angle detection means, when the engine is under low load, detects the start of the compression stroke from the latter half of the intake stroke. A control means is provided for controlling the fuel injection valve and the air injection valve to supply fuel and air to the combustion chamber at a predetermined time. As long as the above fuel injection valve and air injection valve satisfy the above requirements,
It may be installed in the combustion chamber, or it may be installed in an intake boat near the combustion chamber.

(Example) Fig. 1 schematically shows an example in which the present invention is applied to a 4-cylinder 4-cycle engine, and Fig. 2 shows the specific structure of the combustion chamber portion and its vicinity of this engine. . In these figures, 1 is the engine body, 2 is an intake passage consisting of an intake pipe 3 and an intake manifold 4, and 5 is the intake passage 2.
6 is an exhaust manifold. In the embodiment shown in the figure, a primary intake passage 8 and a secondary intake passage 9 are respectively provided in the intake manifold 4 and the secondary intake passage 9 for the combustion chamber 7 of each cylinder of the engine main body 1, and the secondary intake passage 9 is provided with a primary intake passage 8 and a secondary intake passage 9, respectively. A swirl control valve 10 that controls the opening degree of this passage 9 is provided. The operation of this swirl control valve ″10 is controlled by the control unit 40, which will arrive later.
It is controlled via an actuator 11.

A primary intake boat 13 communicating with the secondary intake passage 8, a secondary intake boat 14 communicating with the secondary intake passage 9, and an exhaust boat 15 are opened in the combustion chamber 7 of each cylinder. 1FllrF! at the openings of .14 and 15 at predetermined timings by a valve mechanism (not shown). A primary intake valve 1.6, a secondary intake valve 17 and an exhaust valve 18 are provided to be activated. Further, within the combustion chamber 7, a spark plug 20 is provided, and a fuel injection valve 21 and an air injection valve 22 are also provided. Above fuel injection valve 2
1 is installed toward the spark plug 20. . Furthermore, the air injection valve 22 is disposed close to the fuel injection valve 21 and oriented in a predetermined direction so that the injected air mixes with the injected fuel from the fuel injection valve 21. In addition, in FIG. 1, for convenience of drawing, the arrangement of the fuel injection valve 21 and the air injection valve 22 is shown only for the rightmost cylinder, but the arrangement of the fuel injection valve 21 and the air injection valve 22 is similarly shown for the other cylinders. 22 has been R1.

The fuel injection valve 21 is connected to a fuel injection pump 23. This fuel injection pump 23 has a timing belt 24
It is driven by the crankshaft 27 of the engine via pulleys 25 and 26, and supplies fuel to the fuel injection valve 21 of each cylinder for injection, and the injection start timing and injection end timing are controlled electrically. It has a structure that can be adjusted according to a control signal. Furthermore, the air injection valve 22 is connected to an air pump 30 via an air reservoir 29.
The air pump 30 is driven by the crankshaft 27 via a belt 31 and pulleys 32 and 33. In the figure, an air return passage 3 is shown between the air reservoir 29 and the air pump 30 to promote a pressure increase in the air reservoir 29 during engine startup.
4, and this air return passage 34 is provided with a recycle valve 35 that is opened and closed when the engine is started. 36 is a check valve provided in the air introduction passage 37 to the air pump 30, and 38 is a relief valve provided in the air relief passage 39.

Further, 40 is a control unit for each 1lIIJllI, and includes a control section 41 using a microcomputer and various converters 42 to 45, as shown in FIG. 3, for example. The control section 41 includes an accelerator opening sensor 5
An accelerator opening signal is input from 1 through the A/D converter 42, and the crank angle and F/V are input from the sensor 52.
(Frequency-voltage) transformer 43 and A/D converter 44
An engine rotational speed signal is inputted via the accelerator opening and the engine rotational speed so that the load condition is detected, and a crank angle signal is inputted from a crank angle sensor 52. Furthermore, for control at the time of starting which will be described later, a pressure signal is provided via the A/D converter 45 from the pressure sensor 53 that detects the pressure in the air reservoir 29, and an interwoven signal is provided from the start signal 54.
The start signal as an interrupt signal is also controlled by the control section 41.
has been entered. The control section 41 controls the fuel injection valve 21
It has a function as a control means for controlling fuel injection from the air injection valve 22 and air injection from the air injection valve 22, and directly controls the operation of the fuel injection pump 23 and the opening/closing operation of the air injection valve 22. Further, the actuator 11 of the swirl control valve 10 and the recycle valve 35 are also controlled by the control section 41.

In the control unit 41, the injection start timing and injection end timing of fuel and air under various operating conditions are stored in advance as a data map, and at least when the load is low, fuel and air are injected in the latter half of the intake stroke or in the compression stroke. The injection timing is set so that For example, the map is created so that the timing is controlled according to the characteristics shown in FIG. That is, in FIG. 4, FS and Fe indicate the fuel injection start time and injection end time, respectively, As and 80 indicate the air injection start time and injection end time, respectively, and l indicates the ignition timing. As shown in this figure, in the low load region, fuel and air are injected in the latter half of the compression stroke, and the injection end timings Fe and Ae are made to approximately coincide with the ignition timing (2). Since the fuel and air injection IJffi depends on the injection period 11, the fuel and air injection start timings FS and As are set so that an appropriate injection amount can be obtained depending on the load.

J5, control at high loads is not limited by the present invention, but fuel injection! II! At high loads where l is increased, there is no need for stratified air supply; rather, it is preferable to ignite the fuel in a dispersed state in order to increase air utilization and improve output. For this reason, in the characteristics shown, the higher the load, the more r! When the value increases by 1, the injection timing of fuel and air is advanced, so that fuel is injected in the first half of the intake stroke in a high load region. In addition, at such high loads, the swirl generated in the intake stroke sufficiently promotes atomization and vaporization of the fuel, so in order to avoid unnecessary injection of excess air, the air injection valve is The amount of air jetted from 22 is reduced.

Further, the opening degree of the swirl control valve 10 under various load conditions is stored in advance in the control section 41 as a data map, and the swirl control valve 10 is closed when the load is low, and when the load is high, the swirl is immediately adjusted accordingly. Control valve 10
The map above has been created to combat this.

The control executed by the 11J11j unit 40 is shown in FIGS. 5 and 6 using a 70-chart.

In the main routine shown in FIG. 5, first, detection signals of accelerator opening A and engine rotation speed R, which determine the load condition, are input (step x 1), and based on these signals,
From the map set in advance to give the characteristics shown in FIG. (steps X2, X3)
. Next, after repeatedly inputting the detection signal of the crank angle θ and waiting for the crank angle θ to reach the above-mentioned injection start timings, As and Fs, control is performed to start fuel and air injection (step x 4). ~Xa). Subsequently, after the crank angle θ reaches the injection end timing Ae, Fe while repeatedly inputting the detection signal of the crank angle θ, 1IJn is performed to end the injection of fuel and air (step x 7). ~Xs). Further, in accordance with the accelerator opening degree A and the engine rotation speed R, the opening 11j[(S valve opening) So of the swirl control valve 10 is 1lln, and a control signal giving this opening degree So is output to the actuator 11. (Steps X10 and X11). Then step x
1, and the above steps are repeated.

With such control, during low load, fuel is injected from the fuel injection valve 21 toward the spark plug 20 at a predetermined time in the latter half of the compression stroke, and the fuel is mainly supplied to the vicinity of the spark plug and to other parts of the combustion chamber 7. Ignition occurs when the fuel is lean in some areas. Therefore, even with a small amount of fuel, ignition and combustion are possible, and the engine can be operated. In addition, in this case, there is no problem even if excessive air is supplied from the primary intake passage 8 to the combustion chamber 7, so the throttle valve is omitted in the figure so that the intake air from the primary intake passage 8 is not restricted. Reduces grossness. When fuel is injected toward the spark plug 20 in this way, air is injected from the air injection valve 22, and this air mixes with the injected fuel to efficiently form fuel mist in a short time. Since oxidation and vaporization occur, ignitability is improved.

On the other hand, when the load is high, the fuel injection amount is increased, fuel is injected in the first half of the intake stroke, and the swirl control valve 10 is closed to create a swirl in the combustion chamber 7 by intake air from the secondary intake passage 9. is increased, so the fuel flows into the combustion chamber 7
Ignition will take place after the fuel is sufficiently diffused within the interior.

The interrupt routine shown in FIG. 6 is for controlling the start, and is started by a signal from the start sensor 54. First, a pressure signal from the pressure sensor 53 is input (step Y1), and the pressure P It is determined whether or not is greater than or equal to a set value α (step Y2). If the pressure P is less than the set value α, the recycled pulp 35 is l
Controlled to repeat FIM operation (step Y3),
This helps increase the pressure within the air reservoir 29. When the pressure P exceeds the set value α, the recycle valve 35 is closed and starting fuel and air are injected (step Ya). and,
It is determined whether or not the starting has ended (step Y5), and when the starting has ended, the process returns to the main routine shown in FIG. 5 described above.

7 and 8 show another embodiment of the invention. In this embodiment, a fuel injection valve 21' and an air injection valve 22 are provided in the primary intake boat 13, and in this case as well, the fuel injection valve 21' is arranged toward the spark plug 20 in the combustion chamber 7, and the air injection valve 22 is arranged to mix air into the injected fuel. Further, in this embodiment, the fuel injection valve 21', like the air injection valve 22, is configured so that the nW1 operation is directly controlled by the control unit 4°, and in this case, the fuel injection valve 21' is normally Fuel injection pumps like those used in gasoline engines (
(not shown).

In this way, each of the injection valves 21' and 22 is connected to the intake boat 1.
3, it is necessary to inject fuel before the intake valve 16 closes, so as shown in FIG. Injection start times As, Fs and injection end times Fe, Ae are set.

Note that in each of the above embodiments, the fuel injection valve 21 or 21' and the air injection valve 22 are provided separately; Fuel injector and air #1 as shown in il
It is also possible to use an injection valve 6o that is integrated with a 1114 valve. This injection valve 6o has a water body 61, a nozzle member 62 attached to the tip thereof, and a valve portion 64a that opens an injection port 63 at the tip of the nozzle member 62, and can be moved stepwise into the nozzle member 62. It includes the inserted rod 64 and a spring 66 that biases the rod 64 in the valve closing direction via a piston 65, and a fuel passage 67 and an air passage 68 are formed between the main body 61 and the nozzle member 62. There is.

Each of the passages 67 and 68 is connected to a fuel injection pump and an air pump (not shown), and the tips of each passage 67 and 68 face the injection port 63, and in the middle of the fuel passage 67 there is an intermediate tapered portion 64b of the rod 64. A fuel reservoir 69 is provided for applying fuel pressure to the fuel tank. When fuel is supplied under pressure, the pressure pushes up the rod 64 and opens the injection port 63, so that fuel and air are injected simultaneously.

(Effects of the Invention) As described above, the present invention injects fuel toward the spark plug from the latter half of the intake stroke to a predetermined period of the compression stroke when the engine is under low load, and injects the injected fuel from the air injection valve. Since air is mixed in, the so-called eye-shaped air supply makes it possible to achieve lean combustion and reduce pumping loss, improving fuel efficiency.Furthermore, fuel atomization and vaporization are promoted to improve ignitability and combustibility. This is a significant improvement.

[Brief explanation of drawings]

1vA is an overall schematic diagram showing one embodiment of the present invention, FIG. 2 is an enlarged view of the combustion chamber portion and its vicinity (an enlarged view of the corner), FIG. 3 is a block diagram of the control system, and FIG. 4 (fuel and Characteristic diagram of air injection timing, Figures 5 and 6 are flowcharts, Figure 7 is an overall schematic diagram showing the embodiment of 11, Figure 8 is the cause corresponding to Figure 2, and Figure 9 is based on this embodiment. Case 4
FIG. 10 is a schematic sectional view showing another example of the injection valve, and FIG. 11 is an enlarged sectional view of the main part thereof. 20...Spark plug, 21.21'...Fuel injection valve, 22...Air injection valve, 40...Control unit (
11ilj control means), 51... accelerator opening sensor,
52...Crank angle sensor. Patent applicant: Toyo Kogyo Co., Ltd. Figure 9 Figure 10

Claims (1)

[Claims] 1. A fuel injection valve that is turned toward the spark plug of the engine, an air injection valve that mixes air into the injected fuel from the fuel injection valve, a load detection means that detects the load state of the engine, and a crank of the engine. A crank angle detection means for detecting the angle, and outputs from the load detection means and the crank angle detection means are received, and the fuel injection valve and the air injection valve are operated at a predetermined time from the latter half of the intake stroke to the compression stroke when the engine is under low load. A stratified air supply engine comprising: control means for controlling and supplying fuel and air to a combustion chamber.