JPH04203323A - Air intake device of engine - Google Patents

Abstract

PURPOSE:To provide stable combustion with high efficiency by providing check valves in air intake delayed closing passages which communicate delayed closing circulation flow ports of respective cylinders with delayed closing intake ports of the other cylinders, and fuel injection valves at the downstream of the check valves to make mixture in a layered condition. CONSTITUTION:There are provided delayed closing circulation flow ports 25a, 25b which close later than air intake ports 11a, 11b, and delayed closing intake ports 26a, 26b which are positioned near the leading side than the delayed closing circulation flow ports 25a, 25b and opened at the latter half of the air intake stroke in respective cylinders 3, 4 in a rotary piston engine 1. In this constitution, there are provided air intake delayed closing passages 27a, 27b which communicate delayed closing circulation flow ports 25a, 25b of the respective cylinders 3, 4 with delayed closing intake ports 26a, 26b. Besides, check valves 28a, 28b which allow flow from the delayed closing circulation flow ports 25a, 25b side are provided in the air intake delayed closing passages 27a, 27b, and fuel injection valves 29a, 29b are provided at the downstream of the check valves. By this, it is thus possible to make fuel into particulates by high-speed flow due to air intake delayed closing, and make mixture in a layered condition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine that employs an intake late closing system.

(Prior art) Each cylinder of an engine is provided with a main intake port and an intake slow-close port that closes later than the main intake port, and each cylinder's intake slow-close port is communicated with the intake slow-close port of another cylinder. An intake slow-closing passage is provided to allow a portion of the air-fuel mixture in the cylinder at the beginning of the compression stroke to flow into other cylinders at the front stage of the intake stroke, thereby suppressing the intake negative pressure of the cylinder in the intake stroke and reducing the pumping loss. For example, an intake slow closing system designed to reduce the
It has been proposed in the past as described in Japanese Patent No. 3-71525. Such an intake late-closing system can be realized in a low-return piston engine in which two cylinders are arranged back-to-back by simply providing an intake late-closing passage that penetrates the intermediate housing. In addition to the effect of reducing bombing loss, the compression pressure in the cylinder on the compression stroke side is reduced, so the force pressing the apex seal is weakened, and the sliding resistance is reduced. In addition, by using supercharging means,
By sending in more intake air from the main intake port in advance to account for the amount of air that escapes to other cylinders at the beginning of the compression stroke, it is possible to establish the so-called Miller cycle by closing the intake air late over a wide range of engine operating ranges. It is also known to improve fuel efficiency.

However, when an intake late closing system is used as a means of realizing the Miller cycle, adiabatic compression does not begin until the intake late closing port closes even after entering the compression stroke, so the temperature of the air-fuel mixture at the compression top becomes low. , combustion becomes unstable, especially under light loads. In addition, especially in rotary piston engines, when the side seal of the rotor straddles the intake port at the beginning of the intake stroke and the apex seal straddles the exhaust port at the same time, the working chamber at the beginning of the intake stroke is the side seal on the side of the rotor. By communicating with the late-closing intake port through the clearance between the oil seal and the oil seal, combustion gas from the adjacent working chamber at the beginning of the exhaust stroke flows into this working chamber at the beginning of the intake stroke. 3 = There is a unique phenomenon in which the gas flows into the working chamber during the intake stroke of another cylinder through the port, and as a result, so-called dilution gas increases, further deteriorating combustion stability at light loads. There is. Therefore, it may be possible to control the intake late-closing passage to close it during light loads, but the light-load range is the area where the fuel efficiency improvement effect can be expected the most, and it is likely that the intake late-closing passage was stopped in this area. This means that the fuel efficiency cannot be improved as expected. Further, even if it is attempted to perform opening/closing control by providing a flow rate control valve in the intake slow-closing passage, for example, it is practically impossible to perform this with a good response during a transient period.

By the way, it has been known for a long time to improve combustion by stratified combustion, and even in the case of low-return piston engines, for example, as described in Japanese Patent Application Laid-Open No. 1-216025, fuel is supplied to the leading side of the working chamber during the compression stroke. Attempts have been made to unevenly distribute fuel near the spark plug in the compression top by injecting it. In addition, attempts have been made to utilize stratified combustion as a means to prevent deterioration of combustion due to a decrease in the air-fuel mixture temperature and an increase in dilusion gas in engines that perform intake late closing.
It has been confirmed that stratified combustion can eliminate unstable combustion in the light load range.

(Problem to be Solved by the Invention) However, when injecting fuel into the working chamber of a compression stroke in a low-repetition piston engine, for example, unstuck air is required to atomize the fuel, and the assist air must be supplied under pressure. A pump is required. Therefore, mechanical resistance loss due to pump drive and the like increases, and the effect of improving fuel efficiency by closing the intake air late is correspondingly impaired.

The present invention was made in view of the above-mentioned problems, and is capable of efficiently realizing stable combustion by stratifying the mixture even when the mixture temperature is low and there is a lot of illusion gas, and it is possible to efficiently achieve stable combustion under light load. The purpose of the present invention is to improve fuel efficiency by closing the intake air slowly over a wide range of driving conditions, including times.

(Means for Solving the Problems) The present invention is capable of atomizing and assisting the injected fuel by a high-speed flow in the intake late-closing passage, and its configuration is as follows. That is, the engine intake system according to the present invention includes a main intake port for each cylinder, a late closing reflux port that closes later than the main intake port, and a late closing reflux port that is located on the leading side of the late closing reflux port and opens in the latter half of the intake stroke. A slow-closing intake port is provided, and an intake slow-closing passage is provided that communicates the slow-closing reflux port of each cylinder with the slow-closing intake port of another cylinder,
Furthermore, the present invention is characterized in that a check valve that allows flow from the late-closing recirculation port side to the late-closing suction port side is provided in the intake late-closing passage, and a fuel injection valve is provided downstream of this check valve.

(Function) The air-fuel mixture flows out at high speed from the working chamber at the beginning of the compression stroke from the slow-closing reflux port provided in each cylinder of the engine, and then passes through the intake slow-closing passage to the late-closing intake of other cylinders. It flows to the port and enters the combustion chamber in the latter half of the intake stroke. that time,
By injecting fuel from the combustion injection valve provided in the intake late-closing passage, fuel atomization is performed by the high-speed flow in the intake late-closing passage, and the atomized fuel is unevenly distributed in the combustion chamber. This results in stable stratified combustion.

(Example) Examples will be described below based on the drawings.

FIG. 1 is a system diagram of a two-cylinder rotary piston engine showing one embodiment of the present invention. This rotary piston engine 1 includes two cylinders 3.4, one on the front side and the other on the rear side, which are arranged in series and share an intermediate housing 2. However, in the figure, these two cylinders are shown separated into left and right for convenience.

Each cylinder 3, 4 is connected to the intermediate housing 2. The rotor housing 5.6 is provided with a casing composed of a rotor housing 5.6 and a side housing (not shown).
．． A substantially triangular rotor 8°9 that rotates planetarily along the trochoidal inner peripheral surface of the rotor 6 is disposed. Inside the casing of each cylinder 3, 4, two working chambers 1O, shown as 10a and IOb in the figure, are divided by the flank surfaces of the rotors 8, 9, and each working chamber 10a, IOb is divided by the rotation of the rotor 8°9. As it moves and its volume changes, suction, compression, expansion, and exhaust are repeated in sequence.

In a rotary piston engine with such a configuration,
Working chamber 10a for the intake stroke of each cylinder 3,4.

Intake ports lla and llb are formed on both sides of the intermediate housing 2 corresponding to the intermediate housing 10b, and an exhaust port is formed on the inner surface of the rotor housing 5.6 at a position facing the above-mentioned intake ports 11a and 11b across the short shaft portion. Port +2a, 1
2b is formed.

Then, the intake ports 11a and I of the two cylinders 3 and 4 are
The intake passages 13, 14 communicating with lb are gathered upstream into one upstream intake passage 15, and the upstream intake passage 15
A throttle valve 16 is disposed at the throttle valve 16 . The upstream intake passage 15 has two branch passages 17.
18, and each branch passage 17.18 is provided with a blower 22, 23 driven by two turbines 20.21 of an exhaust turbo supercharger 19-8. Further, an intercooler 24 is provided in the upstream intake passage 15 downstream of the branch point.

On both sides of the intermediate housing 2, the above-mentioned intake port 11a,
Working chamber 10 of each cylinder on the leading side from llb
Late closing reflux ports 25a, 25b open to a, 10b
are provided respectively, and these slow-closing reflux ports 2
Further on the leading side from 5a and 25b, slow-closing suction ports 26a and 26b are provided, respectively, which open to the working chambers Oa and 10b in the latter half of the intake stroke. The slow-closing recirculation port 25a of the front cylinder 3 and the slow-closing intake port 26b of the rear cylinder 4 are communicated through the first intake slow-closing passage 27a, and the slow-closing recirculation port 25b of the rear cylinder 4 and the front side The late closing intake port 26a of the cylinder 3 is communicated with the second intake late closing passage 27b. Further, in the middle of the first and second intake slow closing passages 27a and 27b, a slow closing reflux port 25a,
A check valve 28a allows flow from the side 25b to the late closing suction ports 26a and 26b, and prevents a reverse flow.

28b are provided respectively, and these check valves 28a
, 28b are provided with fuel injection valves 292L and 29b, respectively. Here, each of the late-closing reflux ports 25a and 25b is set to open at 80 to 90 degrees after the intake top dead center and finish closing at 110 to 170 degrees after the intake bottom dead center. In addition, each slow-closing suction port 26a, 26b is
It is set to begin opening at 170 to 200 degrees after the intake top dead center and close at 150 to 200 degrees after the intake bottom dead center.

In such a configuration, as shown in FIG.
In the compression stroke of each working chamber 10a indicated by (+) to (3) of the first cylinder (front cylinder 3), No. 1 after the late closing intake port 26b of the second cylinder (rear cylinder 4) begins to open. Until the slow-closing recirculation port 25a of the cylinder closes, the air-fuel mixture flows at high speed through the first intake slow-closing passage 27a from the No. 1 cylinder side to the No. 2 cylinder side, and similarly the No. 1
In the compression stroke of each working chamber 10b of the two cylinders, No.

After the late-closing intake port 26a of cylinder 1 starts to open, the No.
, the air-fuel mixture flows at high speed through the second intake slow-closing passage 27b from the No. 2 cylinder side to the No. 1 cylinder side until the late-closing recirculation port 25b of the No. 2 cylinder closes. At that time, check valves 28a and 2 are provided in each intake slow closing passage 27a and 27b, respectively.
8b, gas flows in each intake slow closing passage 27a, 27b in only one direction, thereby ensuring effective gas exchange as an intake slow closing system.

Further, from each fuel injection valve 29a, 29b, a late closing intake port 26a, 26 is connected to a late closing intake passage 27a, 27b.
Fuel is injected in accordance with the timing when the air-fuel mixture is sent from b to the working chambers lOa and job in the latter half of the intake stroke. As a result, injection pressure assist and fuel atomization are performed, and the atomized fuel is distributed toward the leading side of the working chambers 10a, 10b. And further rotors 8, 9
The uneven distribution of fuel as described above is maintained until the engine rotates and reaches near compression top dead center, and as a result, stable combustion is achieved even though the air-fuel mixture temperature decreases due to the late intake closing and dilution gas increases. will be realized.

Note that the present invention can also be applied to engines other than rotary piston engines.

(Effects of the Invention) The present invention is configured as described above, and the fuel can be atomized by the high-speed flow caused by the late closing of the intake air, and stable combustion can be efficiently achieved by stratifying the air-fuel mixture. It is possible to improve fuel efficiency by closing the intake air late over a wide range of operating conditions, including under load.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a two-cylinder rotary piston engine showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of the same embodiment. l: rotary piston engine, 2: intermediate housing,
3: Cylinder (front side), 4: Cylinder (rear side), 8, 9
: Rotor, 10a, 10b: Working chamber, Ila, llb:
Intake port (main intake port), 25a, 25b + slow closing reflux port, 26a, 26b: slow closing intake port,
27a, 27b: intake slow closing passage, 28a, 28b: check valve, 29a, 29b: fuel injection valve. Agent Patent Attorney Jun Susumu Fuji −

Claims (1)

[Claims] (1) Each cylinder is provided with a main intake port, a late closing reflux port that closes later than the main intake port, and a late closing intake port that is located on the leading side of the late closing reflux port and opens in the latter half of the intake stroke; An intake slow-closing passage is provided that communicates the late-closing reflux port of each cylinder with the late-closing suction port of another cylinder, and the intake late-closing passage is further provided with a passageway that connects the late-closing reflux port from the late-closing reflux port side to the late-closing suction port side. An intake system for an engine, comprising a check valve that allows flow, and a fuel injection valve downstream of the check valve.