JPH086599B2 - Air intake system for engines with fuel injection system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake device for an engine that includes a fuel injection device and a timing valve provided in an intake passage.

(Prior Art) Conventionally, there are various known intake systems for an engine in which a rotary valve that opens and closes in synchronization with the engine is provided in an intake passage of the engine, and the intake start timing and the intake end timing are adjusted by the rotary valve. Has been. For example, in the device disclosed in Japanese Patent Publication No. 58-55329, a rotary valve is provided downstream of the supercharger of an engine having a supercharger in the intake passage, and the rotary valve is closed earlier than the intake valve is closed. In addition, by adjusting the opening / closing timing, knocking is prevented under high supercharging pressure and high thermal efficiency is ensured.

Further, an engine with a fuel injection device in which a fuel injection valve is provided in the intake passage is generally known. In such an engine, it is required to promote atomization of the fuel injected from the fuel injection valve, and as a means therefor, for example, an air bleed passage communicating with an intake passage upstream of the throttle valve is provided near the fuel injection valve. It is considered that it is opened in the.

By the way, in the engine in which the timing valve is provided in the intake passage as described above, when the fuel injection valve is used as the fuel supply means, even if the air bleed is performed, conventionally, the pressure fluctuation downstream of the timing valve is effectively used. However, the bleed air may not be sufficiently supplied due to insufficient intake force, and there was room for improvement in order to improve atomization of fuel.

(Object of the Invention) In view of such a situation, the present invention effectively utilizes the pressure fluctuation in the intake passage downstream of the timing valve, particularly the pressure difference generated between the intake passages for each cylinder, and An intake device for an engine with a fuel injection device capable of promoting atomization of injected fuel.

(Structure of the Invention) According to the present invention, in an engine in which a timing valve that opens and closes in synchronization with an engine is provided in an intake passage, a fuel injection valve is provided in each intake passage for each cylinder downstream of the timing valve, and the fuel injection valve is provided. A communication passage that opens in the vicinity of and that communicates the cylinder passages of the plurality of cylinders is provided, and the fuel injection timing from the fuel injection valve is a period during which the pressure downstream of the timing valve decreases during the valve closing period of the timing valve. It is set inside.

With this configuration, since the intake passages for each cylinder are sequentially opened and closed by the timing valve in response to the operation sequence of each cylinder, at the time of fuel injection, the pressure between the intake passages that are communicated through the communication passages is increased. A difference occurs, and the pressure difference effectively feeds air for air bleed from the other intake passage into the intake passage where fuel injection is performed.

(Embodiment) FIGS. 1 to 3 show a first embodiment of the present invention. The engine shown in this embodiment is a four-cylinder cycle engine, and a combustion chamber 4 is formed above a piston 3 in each cylinder 2 of the engine body 1, and the combustion chamber 4 is opened and closed by an intake valve 5. The exhaust port 8 opened and closed by the intake port 6 and the exhaust valve 7 is open. The intake port 6 is connected to the intake passage 10, and the exhaust port 8 is connected to the exhaust passage 9
It is connected to the.

The intake passage 10 includes an upstream intake passage 14 provided with an air cleaner 11, an air flow meter 12, and a throttle valve 13, a surge tank 15 communicating therewith, and a cylinder extending from the surge tank 15 to an intake port 6 of each cylinder 2. It consists of a separate intake passage 16.

The intake passage 10 is provided with a timing valve 17 that opens and closes the intake passage 16 for each cylinder in synchronization with the engine. The timing valve 17 is constituted by a rotary valve in which valve holes 18 for the intake passages 16 for each cylinder are formed in a predetermined arrangement corresponding to the operating sequence of each cylinder 2. Then, through a transmission mechanism including pulleys 19 and 20 and a timing belt 21, it is interlocked with the crankshaft 22 so as to rotate at a rotational speed half the engine rotational speed.

Intake passage for each cylinder downstream of the timing valve 17
A fuel injection valve 23 is provided in each of the 16 parts. The fuel injection valve 23 has an injection amount and injection timing controlled by a control unit 24, and the control unit 24 includes an air flow meter 12 and a throttle opening sensor 2.
5, signals from the crank angle sensor 26, the O ₂ sensor 27, etc. are input.

Further, a communication passage 28 is formed for communicating with each intake passage 16 for each cylinder downstream of the timing valve 17. The communication passages 28 open in the vicinity of the injection port of the fuel injection valve 23 in the intake passage 16 for each cylinder, and the opening portion has a large number of small holes 29.

The opening / closing timing of the timing valve 17 and the injection timing from the fuel injection valve 23 in this embodiment are set as shown in FIG. That is, in FIG. 4, line A is the opening / closing timing of the intake valve 5, line B ₁ is the opening / closing timing of the timing valve 17, and the opening timing RO of the timing valve 17 is set later than the opening timing IO of the intake valve 5. The intake valve 5 from the opening timing RO of the timing valve 17
The actual engine intake period is up to the closing timing IC. Further, as shown by the hatched injection pulse C ₁ in FIG. 4, the injection timing from the fuel injection valve 23 is
It is set within a period in which the pressure downstream of the timing valve decreases during the valve closing period of 17, and in this embodiment, the opening timing IO of the intake valve 5 is set.
Is set to the opening timing RO of the timing valve 17.

The opening / closing timing of the timing valve 17 is preferably adjusted according to the operating state of the engine.For example, although not shown in the figure, a phase adjusting mechanism is provided between the timing valve 17 and the transmission mechanism. By controlling this according to the engine speed, the retard amount of the opening timing RO of the timing valve 17 with respect to the opening timing IO of the intake valve 5 is increased on the low rotation side and decreased on the high rotation side. By doing so, it is possible to provide the later-described retarded inertial effect over a wide rotational speed range.

 The operation of the apparatus of this embodiment will be described with reference to FIG.

The timing valve 17 in this embodiment serves to enhance the dynamic effect of intake air. That is, when the negative pressure wave generated in the intake stroke is inverted and reflected by the surge tank 15 into the positive pressure wave and acts on the intake port 6 at the end of intake, a dynamic effect is obtained, but especially the opening timing RO of the timing valve 17 is delayed. When,
Since the negative pressure wave generated in the suction stroke is strengthened, the reverse positive pressure wave is also increased, and thus the filling efficiency is increased by the so-called delayed opening inertia effect.

By the operation of the timing valve 17 as described above, the pressure fluctuation in the cylinder-by-cylinder intake passage 16 downstream of the timing valve 17 becomes as shown by the line D in FIG. The pressure decreases and a large negative pressure is generated during the period up to the opening time RO of. And each cylinder 2
Since the intake stroke is performed in a fixed sequence at predetermined intervals, when one cylinder 2 is in the above period, the cylinder-by-cylinder intake passage 16 and the other cylinder 2 in which the negative pressure is generated through the cylinder 2 are generated. A large pressure difference is obtained between the cylinder-by-cylinder intake passage 16 leading to the cylinder 2 and the cylinder 2 through the communication passage 28 due to this pressure difference.
Air is sent from the other cylinder-by-cylinder intake passage 16 to the vicinity of the fuel injection valve 23 of the cylinder-by-cylinder intake passage 16. Therefore, by injecting the fuel during this period, the air bleeding is favorably performed and the atomization of the fuel is promoted.

In this way, by utilizing the pressure difference between the intake passages 16 for each cylinder downstream of the timing valve 17 at a predetermined time, a large air bleeding action can be provided.

FIG. 5 shows the device of the second embodiment of the present invention, and FIG. 6 shows the opening / closing timing of the intake valve 5 (line A), the opening / closing timing of the timing valve 17 (line B ₂ ) and fuel injection in this embodiment. Timing (indicated by injection pulse C ₂ ),
The pressure fluctuations in each intake passage 10 are shown. Also in the device of the second embodiment, a timing valve 17 is provided in the intake passage 10 and each cylinder-specific passage 16 downstream of the timing valve 17 is provided.
The point where the fuel injection valve 23 is disposed is the same as in the first embodiment. However, in this embodiment, the closing timing RC of the timing valve 17 is set to be earlier than the closing timing IC of the intake valve 5 in order to reduce pumping loss when the load is low, and the injection from the fuel injection valve 23 is performed. The timing is set within the period from the closing of the intake valve 5 to the opening of the timing valve 17 thereafter (see FIG. 6).

Further, the communication passage opening near the fuel injection valve 23 is
A communication passage that connects the intake passages 16 for each cylinder of the fourth cylinder to each other
28a and the intake passage 16 for each cylinder of the second and third cylinders is divided into a communication passage 28b that communicates with each other.

In the case of this embodiment, the opening of the throttle valve 13 is made relatively large in advance even when the load is low, and the required amount of intake air is close to the atmospheric pressure while both the timing valve 17 and the intake valve 5 are open. As a result, the pumping loss is reduced. And the timing valve
The pressure in the intake passage 16 for each cylinder downstream of 17 is shown by the line E in FIG.
The negative pressure is maintained until the timing valve 17 is sequentially opened by decreasing the pressure after the timing valve 17 is closed. Also, the intake stroke of each cylinder is 1st, 3rd,
This is done in the order of the 4th and 2nd cylinders. Therefore, by setting the fuel injection timing as described above, for example, the first
At the injection timing for the cylinder, the negative pressure is maintained at the first
Air is sent from the cylinder-by-cylinder intake passage 16 of the fourth cylinder during the rotary valve opening period to the cylinder-by-cylinder intake passage 16 through the communication passage due to the pressure difference between the cylinders. At each injection timing for the third cylinder and the fourth cylinder, air is sent from the other intake passage 16 to the respective cylinder-specific intake passages 16. Thus, air bleeding is effectively performed in this embodiment as well.

FIG. 7 shows an apparatus according to the third embodiment of the present invention. In this embodiment, in addition to the main intake passage 32 communicating with the main intake port 31, a supercharging passage 34 communicating with the supercharging port 33 is formed, and the supercharging passage 35 and the intercooler 36 are provided in the supercharging passage 34. A timing valve 17 'is provided for arranging a relief passage 37 for surplus supercharging air and a surge tank 38, and for opening and closing a cylinder-specific supercharging passage 39 downstream of the surge tank 38. And
The fuel injection valve 23 is disposed in each cylinder supercharging passage 39 downstream of the timing valve 17 ', and a communication passage 28' for communicating the cylinder supercharging passage 39 with each other is opened near the fuel injection valve 23. In this embodiment, the communication passage 28 'is opened at a position facing the injection port of the fuel injection valve 23.

In the apparatus of this embodiment, 'while being opened and closed as indicated by the timing valve 17' supercharged air intake valve 40 provided in the supercharger port 33 the line A in FIG. 8 is the line B ₃ As described above, the supercharging intake valve 40 is opened at a time later than the opening timing, and the supercharging passage 34 is set to be open during the period from the end of the intake stroke to the middle of the compression stroke.

According to the apparatus of this embodiment, the supercharged air is supplied to the combustion chamber 4 from the end of the intake stroke to the compression stroke. Then, the pressure downstream of the timing valve 17 'becomes as shown by the line F in FIG. 8, and the pressure decreases from the opening of the supercharging intake valve 40 to the opening of the timing valve 17', and this The timing is different for each cylinder. Therefore, also in this embodiment,
By setting the fuel injection timing shown by the injection pulse C ₃ in FIG. 8 between the opening timing of the supercharging intake valve 40 and the opening timing of the timing valve 17, effective air bleeding is performed. Be done.

(Effects of the Invention) As described above, according to the present invention, the fuel injection valve is disposed downstream of the timing valve, and the communication passage that opens in the vicinity of the fuel injection valve and communicates the intake passages for each cylinder with each other is provided. In addition, since the fuel is injected during the period in which the pressure downstream of the timing valve decreases during the timing valve closing period, the pressure difference between the intake passages downstream of the timing valve is effectively used and good. Air bleeding is performed on the fuel cells, which promotes atomization of the fuel and enhances the combustibility.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a first embodiment of the present invention, FIG. 2 is a schematic side view of the same, FIG. 3 is an enlarged view of the vicinity of a communication passage opening, and FIG. 4 is a valve opening / closing timing for each cylinder and Explanatory drawing showing fuel injection timing and pressure downstream of the timing valve, FIG. 5 is a schematic plan view showing the second embodiment,
FIG. 6 is an explanatory diagram showing the valve opening / closing timing and fuel injection timing for each cylinder and the pressure downstream of the timing valve in the case of the apparatus of the second embodiment, and FIG.
FIG. 8 is a schematic side view showing an embodiment, and FIG. 8 is an explanatory view showing valve opening / closing timings, fuel injection timings, and pressures downstream of the timing valves for each cylinder in the case of the apparatus of the third embodiment. 1 ... Engine body, 2 ... Cylinder, 16,34 ... Intake passage (supercharging passage) for each cylinder, 17,17 '... Timing valve, 23 ... Fuel injection valve, 28, 28' ... aisle.

Claims (1)

[Claims] 1. An engine having a timing valve that opens and closes in synchronization with an engine in an intake passage, and a fuel injection valve is provided in each intake passage for each cylinder downstream of the timing valve, and an opening is provided near the fuel injection valve. Then, a communication passage that connects the respective cylinder passages of a plurality of cylinders is provided, and the fuel injection timing from the fuel injection valve is set within the timing when the pressure downstream of the timing valve decreases during the valve closing period of the timing valve. An intake device for an engine with a fuel injection device, which is characterized in that: