JPH0722035U - Engine intake system - Google Patents

Abstract

(57) [Summary] [Purpose] Stabilize the combustion state when the engine is cold and reduce exhaust gas emissions, while achieving stratified combustion with turbulent combustion in the low and medium load regions of the engine. An intake system for an engine is provided. [Structure] An intake port 8 whose downstream portion is branched into two to generate a tumble flow in a cylinder 4, and a central passage 8a communicating with the vicinity of the central portion of a combustion chamber 7 in which an ignition plug 12 is installed. , A pair of left and right side passages 8b located on the left and right sides thereof and communicating with the vicinity of the peripheral portion of the combustion chamber 7,
8c and the intake port 8 divided into 3 and the central passage 8
an injector 14 that injects fuel into a, a tumble control valve 15 that opens and closes the central passage 8a on the intake upstream side of the injector 14, and a tumble control valve 15 that is closed in the low and medium load regions according to the engine load region. , Equipped with a control unit that controls opening and closing to open in high load areas,
When the engine is cold, the control unit operates the tumble control valve 15
Is an intake device for an engine in which the central passage 8a is opened by controlling the opening.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an engine intake device capable of generating a tumble flow in a cylinder, and more specifically, stabilizes combustion in an engine cold state by promoting vaporization of fuel injected from an injector into an intake port, The present invention relates to an engine intake device that reduces exhaust gas emissions.

[0002]

[Prior art]

 As a combustion method for engines, stratified charge combustion, in which a rich mixture is generated near the spark plug and ignited by this, and combustion is advanced by flame propagation, the ignitability is good and the combustion is stable, and as a whole, it is empty. Lean combustion with a large fuel ratio is possible, which is effective in improving fuel efficiency in the low and medium load range of the engine. In addition, the generation of the tumble flow that swirls the intake air-fuel mixture along the axial direction in the cylinder causes the tumble flow to collapse in the latter half of the compression stroke to generate a strong turbulent flow, which is ignited to generate the combustion speed. It is effective for improving engine combustion because it provides stable turbulent combustion with fast combustion.

Therefore, conventionally, an intake system for an engine has been proposed in which stratified charge combustion accompanied by turbulent combustion by a tumble flow is achieved in a low load region of the engine (see Japanese Patent Publication No. 4-8610). This intake device has a central passage that communicates with the inside of the intake port, which has two branches on the downstream side, in the vicinity of the center of the combustion chamber where the spark plug is installed, and on the left and right sides of the central passage, near the periphery of the combustion chamber. The engine is divided into a pair of left and right side passages that communicate with each other, and an injector for injecting fuel into the central passage and a tumble control valve for opening and closing the central passage upstream of the injector are provided. In the low load region of the engine, the tumble control valve is closed and fresh air is sucked from only a pair of left and right side passages, thereby forming a rich mixture near the spark plug in the combustion chamber and sucking it into both sides of the cylinder. It is designed to generate a tumble flow using only air.

[0004]

[Problems to be solved by the device]

 Here, in the intake device described in Japanese Patent Publication No. 4-8610, fuel is injected from the injector into the central passage of the intake port, so that the fuel is discharged when the engine wall temperature of the central passage is low. Easy to attach to the wall of the central passage. In particular, even when the engine is in a cold state where such fuel adhesion is likely to occur, the tumble control valve closes the central passage of the intake port to stop fresh air intake from the central passage. There are problems that the vaporization of fuel is delayed and it is difficult to obtain the air-fuel mixture as set, the combustion state becomes unstable, and exhaust gas emission deteriorates.

Therefore, the present invention is capable of achieving stratified charge combustion accompanied by turbulent combustion in the low and medium load regions of the engine, while stabilizing the combustion state in the cold state of the engine and reducing exhaust gas emissions. It is an object of the present invention to provide an intake system for an engine that can be used.

[0006]

[Means for Solving the Problems]

 For this purpose, the intake system of the engine according to the present invention is an intake port whose downstream part is bifurcated so as to generate a tumble flow in the cylinder, and is located near the center of the combustion chamber where the spark plug is installed. An intake port divided into three parts, a central passage communicating with each other, and a pair of left and right side passages located on both left and right sides of the central passage and communicating with the vicinity of the periphery of the combustion chamber, respectively, and fuel injection into the central passage. The injector, the tumble control valve that opens and closes the central passage on the intake upstream side of this injector, and the tumble control valve that closes in the low and medium load range and opens in the high load range according to the engine load range. In the intake system of the engine including the control unit, the control unit is configured to open the tumble control valve when the engine is cold.

[0007]

[Action]

 In the intake system for an engine according to the present invention employing such means, the control unit closes the tumble control valve to close the central passage of the intake port in the low and medium load range of the engine. Therefore, in the intake stroke of the engine, fresh air is symmetrically sucked into the cylinder through only a pair of left and right side passages of the intake port, and a tumble flow of fresh air is generated in the cylinder. It At that time, the fuel injected from the injector into the vicinity of the central portion of the combustion chamber through the central passage of the intake port is wrapped in a fresh air tumble flow to form a rich mixture near the spark plug. During the compression stroke of the engine, the rich air-fuel mixture wrapped in the tumble flow stays near the spark plug, and in the latter half of the compression stroke the tumble flow collapses and becomes turbulent, and the spark plug becomes turbulent. By directly igniting the rich air-fuel mixture, stratified charge combustion with good ignitability and stable turbulent combustion with high burning velocity is performed.

Further, in the high load region of the engine, the control unit controls the opening of the tumble control valve to open the central passage of the intake port. Therefore, in the intake stroke of the engine, a large amount of fresh air is sucked into the cylinder through the pair of left and right side passages of the intake port and the central passage, while the fuel injected from the injector passes through the central passage. While mixing with fresh air, it becomes a uniform mixture and is sucked into the cylinder. Therefore, in the high load region of the engine, uniform charging with high charging efficiency and high output is performed.

Here, when the engine is in a cold state such as when the engine is started, since the intake port is also cold, the fuel injected from the injector is likely to adhere to the wall surface of the central passage. However, when the engine is cold, the control unit opens the tumble control valve to open the central passage of the intake port, so that fresh air also passes through the central passage during the intake stroke of the engine. The vaporization of the fuel adhering to the wall surface of the central passage and the fuel injected from the injector is promoted by the passage of the gas. Therefore, the air-fuel mixture according to the set value is supplied to the combustion chamber, the combustion state is stabilized, and the exhaust gas emission is reduced.

[0010]

【Example】

 Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. In FIG. 2, which shows an overall schematic structure of an engine intake device according to one embodiment, reference numeral 1 denotes an engine body in which a cylinder head 3 is assembled to a cylinder block 2, and a piston 5 is slidably mounted on a cylinder 4 of the cylinder block 2. It is movably fitted. Further, as shown in FIG. 1, the cylinder head 3 is connected to the combustion chamber 7 via an intake port 8 communicating with the combustion chamber 7 via a pair of left and right intake valves 6a, 6b and a pair of left and right exhaust valves 9a, 9b. An exhaust port 10 that communicates is formed. The end of the intake manifold 11 is continuously connected to the intake port 8 on the mounting surface 3a of the cylinder head 3. An ignition plug 12 is installed in the center of the combustion chamber 7.

The intake port 8 has a two-way downstream branch to communicate with the combustion chamber 7 via a pair of left and right intake valves 7a and 7b. Similarly, the exhaust port 10 also has a pair of left and right exhaust valves 9a. , 9b, the upstream portion is branched into two in order to communicate with the combustion chamber 7.

Here, the intake passage extending from the inside of the connection end portion of the intake manifold 11 to the entire inside of the intake port 8 includes a central passage 8a and side passages 8b and 8c on both left and right sides thereof by a pair of left and right partition walls 13a and 13b. The central passage 8a is divided into two parts, the downstream portion is branched into two, and communicates with the vicinity of the central portion of the combustion chamber 7 via a pair of left and right intake valves 6a, 6b, and the side passages 8b, 8c correspond to each other. Through the intake valves 6a, 6b of the above, and communicates with the vicinity of the peripheral portion of the combustion chamber 7.

The cylinder head 3 is provided with an injector 14 that injects fuel from a position upstream of the branch point of the central passage 8a toward the pair of left and right intake valves 6a and 6b. Further, the intake manifold 11 is provided with a tumble control valve 15 for opening and closing the inlet of the central passage 8a.

The tumble control valve 15 is of a butterfly valve type which is opened / closed by operating a lever of an electromagnetic plunger 16, and the electromagnetic plunger 16 is drive-controlled by an engine control unit 17 shown in FIG. That is, the engine control unit 17 uses the engine temperature signal from the cooling water temperature sensor 18, the intake air amount signal from the air flow meter 19, and the throttle opening signal from the throttle sensor 20 as input signals for the engine temperature. Also, the drive of the electromagnetic plunger 16 is controlled by searching the data map stored in advance according to the engine load region.

Here, the control mode of the tumble control valve 15 by the engine control unit 17 will be briefly described. In the case where the temperature detected by the cooling water temperature sensor 18 is T1 or less and the engine can be considered to be in a cold state. First, the electromagnetic plunger 16 is drive-controlled so that the tumble control valve 15 is opened preferentially. When the detection temperature of the cooling water temperature sensor 18 is equal to or higher than T2 and it can be considered that the engine has finished warming up, the tumble control valve 15 is closed in the low and medium load regions according to the engine load to close the high load region. At this time, the electromagnetic plunger 16 is drive-controlled to open the tumble control valve 15.

Next, the operation of the engine air intake device having the above-described configuration according to the embodiment will be described. First, in a cold state such as when the engine is started, the temperature detected by the cooling water temperature sensor 18 is T1 or lower, so the engine control unit 17 causes the tumble control valve 15 to open the central passage 8a of the intake port 8 by the electromagnetic plunger. 16 drive control. Therefore, in the intake stroke in which the pair of left and right intake valves 6a and 6b are opened when the engine is in a cold state, as shown in FIG. 1, fresh air from the intake manifold 11 passes through the central passage 8a of the intake port 8 and the left and right intake ports 8a. It is sucked into the cylinder 4 through the side passages 8b and 8c.

At this time, the fuel injected from the injector 14 in the central passage 8a toward the left and right intake valves 6a, 6b is promoted to be vaporized by the fresh air passing through the central passage 8a to form a uniform mixture. And is sucked into the cylinder 4. At this time, the wall surface of the central passage 8a is cold and the injected fuel is likely to adhere to it, but the adhering fuel is also promoted to vaporize by the fresh air passing through the central passage 8a. The mixture will be supplied according to the set value. Therefore, the combustion state becomes stable when the engine is cold, and exhaust gas emissions are reduced.

When the engine warm-up is completed and the temperature detected by the cooling water temperature sensor 18 becomes T2 or higher, the engine control unit 17 controls the opening and closing of the tumble control valve 15 according to the engine load. In the load region, the tumble control valve 15 drives and controls the electromagnetic plunger 16 so as to close the central passage 8a of the intake port 8. Therefore, in the intake stroke in which the pair of left and right intake valves 6a and 6b are opened in the low load region after the engine is warmed up, as shown in FIG. 4, fresh air from the intake manifold 11 flows to the left and right of the intake port 8 as shown in FIG. The air is sucked into the cylinder 4 symmetrically through only the pair of side passages 8b and 8c. In this way, as the piston 5 descends, the symmetrical new air flow sucked into the cylinder 4 eventually collides and reverses upward, so that a tumble flow of fresh air as shown by an arrow in FIG. Is generated. At this time, the fuel injected from the injector 14 in the central passage 8a toward the left and right intake valves 6a, 6b is wrapped in the fresh air tumble flow, and is concentrated near the spark plug 12 in the center of the combustion chamber 7. Form Qi.

The rich mixture thus formed is wrapped in the tumble flow even during the compression stroke of the engine and stays in the vicinity of the spark plug 12, and the tumble flow collapses in the latter half of the compression stroke, so that the vicinity of the spark plug 12 is destroyed. The rich mixture also becomes turbulent. The ignition plug 12 directly ignites the turbulent rich mixture in this way, so that in the low load region after the engine is warmed up, the ignitability is good, and the stratified combustion with stable turbulent combustion with a high burning speed is performed. Burning takes place. Therefore, lean combustion can be performed in the low and medium load range of the engine, and thermal efficiency and fuel efficiency can be improved.

On the other hand, in the high load region of the engine, the engine control unit 17 controls the electromagnetic plunger 16 so that the tumble control valve 15 opens the central passage 8 a of the intake port 8. For this reason, in the intake stroke in which the pair of left and right intake valves 6a and 6b are opened in the high load region after the engine is warmed up, as shown in FIG. Is sucked into the cylinder 4 via the side passages 8b, 8c and the central passage 8a. At that time, the fuel injected from the injectors 14 in the central passage 8a toward the left and right intake valves 6a, 6b is mixed with a large amount of fresh air passing through the central passage 8a to form a uniform mixture, and thus the cylinder 4 Inhaled into. Therefore, in the high load region after engine warm-up, good uniform combustion with high charging efficiency is performed, and high output is maintained.

[0021]

[Effect of device]

 As described above, in the present invention, the control unit closes the tumble control valve to close the central passage of the intake port in the low and medium load regions of the engine, so that the fresh air is paired on the left and right during the intake stroke of the engine. The air is sucked into the cylinder symmetrically through only the side passages, and a tumble flow of fresh air is generated in the cylinder. At that time, the fuel injected from the injector near the center of the combustion chamber is surrounded by the tumble flow of fresh air and forms a rich mixture near the spark plug. During the compression stroke of the engine, the rich air-fuel mixture wrapped in the tumble flow stays near the spark plug, and the tumble flow collapses and becomes turbulent in the latter half of the compression stroke. The spark plug ignites directly in the mixture. Therefore, according to the present invention, it is possible to achieve the stratified charge combustion with good ignitability and stable turbulent combustion with a high burning rate.

Here, in a cold state such as when the engine is started, since the intake port is also cold, the fuel injected from the injector is likely to adhere to the wall surface of the central passage. However, when the engine is cold, the control unit opens the tumble control valve to open the central passage of the intake port, so that fresh air also passes through the central passage during the intake stroke of the engine. The vaporization of the fuel adhering to the wall surface of the central passage and the fuel injected from the injector is promoted by the passage of the gas. Therefore, according to the present invention, it is possible to generate the air-fuel mixture according to the set value even when the engine is cold, stabilize the combustion state when the engine is cold, and reduce exhaust gas emissions.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the overall schematic configuration and operation of an embodiment of an engine air intake device according to the present invention.

FIG. 2 is a vertical cross-sectional view illustrating the overall schematic configuration and operation of one embodiment.

FIG. 3 is a block configuration diagram of a control system in one embodiment.

FIG. 4 is a cross-sectional view showing the overall schematic configuration and operation of one embodiment.

[Explanation of symbols]

 1 Engine Body 2 Cylinder Block 3 Cylinder Head 4 Cylinder 5 Piston 6a, 6b Intake Valve 7 Combustion Chamber 8 Intake Port 8a Central Passage 8b, 8c Side Passage 9a, 9b Exhaust Valve 10 Exhaust Port 11 Intake Manifold 12 Spark Plug 13a, 13b Partition wall 14 Injector 15 Tumble control valve 16 Electromagnetic plunger 17 Engine control unit 18 Cooling water temperature sensor 19 Air flow meter 20 Throttle sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02M 69/00 360 BC

Claims (1)

[Scope of utility model registration request] 1. A central passage communicating with the vicinity of the central portion of a combustion chamber where a spark plug is installed, and an intake port whose downstream portion is branched into two to generate a tumble flow in a cylinder, and both left and right sides thereof. Located at the intake port, which is divided into a pair of left and right side passages that communicate with each other near the periphery of the combustion chamber, an injector for injecting fuel into the central passage, and an intake port upstream of this injector. In an intake system for an engine, which includes a tumble control valve that opens and closes the central air passage, and a control unit that controls the opening and closing of the tumble control valve to close in a low and medium load region and open in a high load region according to the engine load region, An intake system for an engine, wherein the control unit controls opening of the tumble control valve when the engine is in a cold state.