JPH0347465A - Fuel supply device for engine - Google Patents

Abstract

PURPOSE:To enhance the performance of an engine by allowing a fuel injection valve to make two injections under the suction stroke intermittently, mixing the fuel with the air thoroughly in each divergent passage, and making uniform the mixing of fuel with the suction air in the combustion chamber. CONSTITUTION:Exhaust valves 24 and suction valves 12, 12' make opening/ closing motions one after another in the exhaust and suction strokes of an engine 1. In a short period centering on the suction valves 12, 12' making simultaneous valve opening motions, a fuel injection valve 19 injects the fuel as the first injecting run in the timing immediately before a piston 6 reaches the upper fulcrum, like the arrow A. With a small pause inserted, the injection valve 19 injects the fuel as the second injecting run before or after the piston 6 has reached the upper dead point, like the arrow B. Under low speed operation, on the other hand, a single mode injection is conducted as shown by the arrow C. This manner of two runs of injecting prevents the fuel from being injected concentratedly to the suction air which has unsatisfactory flow speed, and thus the engine performance is kept good.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel supply device for an engine that is equipped with a fuel injection valve that injects fuel into an intake passage having a plurality of branch passages.

(Prior Art) Some engine intake systems are configured as follows in order to increase intake efficiency.

That is, an intake passage connected to a combustion chamber in the cylinder is branched into a plurality of branch passages from an intermediate portion thereof to the combustion chamber. Further, an intake valve is provided to open and close each of the branch passages opening into the combustion chamber, and the valve bodies of each of these intake valves are offset from each other in a direction perpendicular to the intake camshaft, and the intake passage A fuel injection valve is provided to inject fuel into the engine.

When each of the intake valves opens and air is forcefully sucked into the combustion chamber through the intake passage, the fuel injected by the fuel injection valve is disturbed and mixed by the intake air to form an air-fuel mixture. It is supplied into the combustion chamber and burned there.

(Problems to be Solved by the Invention) Incidentally, each of the above-mentioned branch passages has a different length and shape, and therefore the flow resistance of the intake air in these branch passages is different from each other. Therefore, with the time when the intake valve opens as the reference time, the time from this reference time until the flow velocity of the intake air in the branch passage reaches a predetermined velocity (hereinafter simply referred to as arrival time) is the time for each branch passage. They are different from each other.

In this case, when fuel is injected into the intake air, the fuel is supplied to the combustion chamber together with the intake air before the flow velocity of the intake air reaches a predetermined speed in the branch passage where the arrival time is long. In this case, the intake air and fuel may not be sufficiently mixed, which may impede improvement in engine performance.

Therefore, one idea is to inject fuel after the flow velocity of intake air reaches a predetermined speed in the branch passages where the arrival time is long, so that the fuel is sufficiently mixed with the intake air in both branch passages. It will be done.

However, if this is done, the fuel is not mixed with the initial intake air taken into the combustion chamber, which is undesirable because the mixture of the intake air and fuel in the combustion chamber becomes non-uniform.

(Object of the Invention) This invention has been made with attention to the above-mentioned circumstances, and it is possible to mix fuel as thoroughly as possible with the intake air in each branch passage, and to prevent the intake air from entering the combustion chamber. and fuel are evenly mixed,
The purpose is to improve engine performance.

(Structure of the Invention) A feature of the present invention for achieving the above object is that the fuel injection valve intermittently performs counter-injection during the intake stroke.

(for production) The effects of the above configuration are as follows.

In the intake stroke, the fuel injection valve 19 intermittently injects counterclockwise, so in the branch passage 11 where the arrival time is short, the fuel injected into the intake air in the first injection is sufficiently absorbed into the intake air. The mixture is mixed and supplied to the combustion chamber 7. In addition, at this time, in the branch passage 11' where the arrival time is long, the velocity of the intake air is insufficient, so the mixing of fuel into the intake air may not be sufficient. Due to this injection, a predetermined amount of fuel is mixed with the initial intake air taken into the combustion chamber 7, and therefore, with the subsequent second injection, the intake air and fuel are mixed in the combustion chamber 7. Non-uniform mixing is prevented.

Moreover, at the time of the second injection, the intake air reaches a predetermined speed even in the branch passage 11' which takes a long time to reach, so at this time, in either branch passage 11.11',
The fuel is sufficiently mixed with the intake air, and in this state the combustion chamber 7
It will be supplied to

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

In FIGS. 1 and 2, 1 is a four-stroke engine installed in a car, cylinders 2 of this engine 1 are arranged side by side to form a cylinder block 3, and a cylinder head 4 is mounted on this cylinder block 3. A piston 6 connected to a crankshaft is fitted into the cylinder 2 so as to be vertically slidable. Then, the cylinder block 3, cylinder head 4. A space surrounded by the piston 6 is a combustion chamber 7, and an ignition plug 7a facing approximately the center of the combustion chamber 7 is provided.

An intake passage 9 is formed on the left side of the cylinder head 4 (referring to the direction as viewed in FIG. 1, hereinafter referred to as the same), which extends from the surge tank 8 to the combustion chamber 7. This intake passage 9 is formed of a main passage 10 connected to the surge tank 8, and three branch passages 11.11' branching from this main passage 10 toward the combustion chamber 7.
The middle branch passage 11 of the combustion chamber 1' is located on an extension of the main passage 1O in plan view (FIG. 2) and extends toward the center of the combustion chamber 7. Further, the branch passages 11 and 11' on both sides are substantially symmetrical with the intermediate branch passage 11 in between, and both extend toward the side of the combustion chamber 7.

The branch boats 11a and 11a' in which the branch passages 11 and 11' open into the combustion chamber 7 have the same diameter, and these
They are arranged in parallel on the left upper surface of the combustion chamber 7 in the substantially circumferential direction of the two cylinder axes. For this reason, the branch passages 11', 11' on both sides are longer in length than the branch passage 11 in the middle.

Further, an intake valve 12.12' is provided to open and close each branch port 11a, 11a, and an intake valve 12.12' is provided to open and close each branch port 11a, 11a'.
A spring 14 is provided to bias the .

A cam chamber 15 formed in the upper part of the cylinder head 4 is provided with an intake camshaft 16 that interlocks with the crankshaft. This intake camshaft 16 is connected to the intake valves 12, 1.2.
The cam engages with the upper end side of the intake valve 12, 12', and opens the intake valves 12, 12' appropriately against the spring 14 in synchronization with the crankshaft.

At this time, these intake valves 12 and 12' are opened and closed at the same time.

By the way, as mentioned above, each intake valve 12, 12' opens and closes at the same time, but as mentioned above, the intermediate branch passage 11
Since the branch passages 11' and 11' on both sides are longer in length, the arrival time is shorter in the intermediate branch passage 11.
In comparison, the arrival time is longer in each of the branch passages 11' on both sides.

A fuel injection valve 19 is provided to inject fuel into the intake passage 9. This fuel injection valve 19 has three injection holes, and the middle fuel injection direction 19a is located at the hole center of the middle branch boat lla and on both sides on the upper surface of the combustion chamber 7, as seen from the side view (Fig. 1). It passes between the hole center of the branch boat lla' and intersects with the hole center of the intermediate branch boat lla in plan view (FIG. 2). Further, fuel injection directions 19a on both sides,
19a is oriented in the same direction as the intermediate fuel injection direction 19a in side view (Fig. 1), but in plan view (Fig. 2), it intersects with the hole center of the branch boat lla' on both sides. .

Meanwhile, a pair of exhaust boats 23 and 23 are formed on the right side of the cylinder head 4 to communicate the combustion chamber 7 with the outside. Exhaust valves 24 and 24 that open and close each of these exhaust ports 23
An exhaust valve 24 is provided to close each exhaust port 23.
A spring 25 is provided to bias the . Further, the cam chamber 15 is provided with an exhaust camshaft 26 that is interlocked with the crankshaft. This exhaust camshaft 26 is connected to each exhaust valve 2 mentioned above.
4, and opens these exhaust valves 24 appropriately against a spring 25 in synchronization with the crankshaft.

In FIG. 3, during the exhaust and intake strokes of the engine I, each exhaust valve 24 and each intake valve 12.12' sequentially open and close, and each intake valve 12.12' simultaneously opens. From immediately before to immediately after the operation, and immediately before the piston 6 reaches the top dead center, the fuel injection valve 19 injects fuel as a first injection, as shown by arrow A in the figure. Then, after some rest period t, and before and after the piston 6 reaches the top dead center, the fuel injection valve 19 injects fuel as a second injection as shown by arrow B in the figure. .

On the other hand, during low-speed rotation, only a single injection is performed as shown by arrow C in the figure, and the timing and period of this injection almost coincide with the first injection. Note that during this low-speed rotation, the fuel may be injected counterclockwise as well as during high-speed rotation.

Further, in the above case, regardless of whether the engine is rotating at high or low speed, the injection timing, injection period, and rest period t of the fuel injection valve 19 are arbitrarily adjusted by an electronic control device linked to the crankshaft.

According to the above embodiment, there are the following effects. That is, during high-speed rotation, the flow velocity of the intake air in each branch passage 11, 11' tends to fluctuate greatly. However, according to the above-mentioned embodiment, because of the countersunk injection, it is possible to prevent the fuel from being intensively injected into the intake air whose flow velocity is insufficient.

In other words, even if the flow velocity of the intake air fluctuates, the mixture of the intake air and fuel is averaged, and insufficient mixing is prevented, thereby maintaining good engine performance.

FIG. 4 shows another embodiment.

According to this, the intake valves 1 on both sides are
2' and 12' have earlier opening and closing timings.

Furthermore, injection during low-speed rotation starts in the middle of the first injection and ends in the middle of the second injection.

Other configurations and operations are similar to those of the previous embodiment.

Note that although the above is based on the illustrated example, the branch ports 11a, 1
1a' may be two or four.

(Effects of the Invention) According to the present invention, the intake passage connected to the combustion chamber in the cylinder is branched into a plurality of branch passages from its midpoint to the combustion chamber, and each of the branch passages opens into the combustion chamber. In an engine that is provided with intake valves that open and close branch boats, the valve bodies of these intake valves are offset from each other in a direction perpendicular to the intake camshaft, and a fuel injection valve that injects fuel into the intake passage, During the intake stroke, the fuel injection valve injects intermittently in countersunk injections, so in the branch passage where the arrival time is short, the fuel injected into the intake air during the first injection is sufficiently mixed with this intake air. and supplied to the combustion chamber. Further, in this case, in the branch passage where the arrival time is long, the velocity of the intake air is insufficient, so there is a possibility that the mixing of fuel into the intake air is not sufficient. However, due to this first injection, a predetermined amount of fuel is mixed with the initial intake air that is drawn into the combustion chamber, and therefore, due to the subsequent second injection, the intake air is injected into the combustion chamber. Non-uniform mixing of air and fuel is prevented.

Moreover, during the second injection, the intake air reaches a predetermined speed even in the branch passages that take a long time to reach, so at this time, fuel is sufficiently mixed with the intake air in any of the branch passages, and in this state, It will be supplied to the combustion chamber.

Therefore, the intake air and fuel are mixed sufficiently and uniformly in the combustion chamber as a whole.
Improved engine performance is achieved.

[Brief explanation of drawings]

The figures show an embodiment of the invention, in which Fig. 1 is an overall side sectional view, Fig. 2 is a simplified plan view, Fig. 3 is a graph, and Fig. 4 is another embodiment, which corresponds to Fig. 3. It is a diagram. ■...Engine, 2...Cylinder, 7...Combustion chamber, 9...
・Intake passage, 11.11' ・Branch passage, 12.1
2'...Intake valve, 19...Fuel injection valve.

Claims (1)

[Claims] 1. An intake passage connected to a combustion chamber in a cylinder is branched into a plurality of branch passages from an intermediate part thereof to the combustion chamber,
A fuel injection valve that includes intake valves that open and close the branch passages that open into the combustion chamber, and that injects fuel into the intake passage by deviating the valve bodies of the intake valves from each other in a direction perpendicular to the intake camshaft. A fuel supply device for an engine, wherein the fuel injection valve intermittently injects twice during the intake stroke.