JPH048609B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a three-valve internal combustion engine having two intake valves and one exhaust valve.

(Conventional technology) In internal combustion engines that will be put into practical use in the future, it is necessary to improve fuel efficiency while reducing harmful components such as carbon monoxide and unburned hydrocarbons in exhaust gas without reducing performance or thermal efficiency. has become an important issue.

In order to reduce the emissions of harmful components and improve fuel efficiency, methods have been used to use a desired mixture or a mixture containing recirculated exhaust gas, but these methods are especially difficult to use during low-load operation. During constant speed and low load operation, the volumetric efficiency of the air-fuel mixture sucked into the combustion chamber is low, and
Since there is a large amount of residual gas, ignitability is poor, and the combustion speed of the flame is low, resulting in slow propagation speed and unstable combustion. Therefore, there is a problem that the thermal effect is low and the operation is not smooth.

In order to improve engine performance, efficiency, and fuel efficiency while reducing harmful components in exhaust gas, it is most important to improve the combustion of the engine itself, that is, to increase the combustion speed. In recent years, in order to deal with this problem, methods have been adopted to create appropriate turbulence in the air-fuel mixture to increase the combustion rate, to promote vaporization, or to make the distribution uniform.

One of these methods is to create a swirl inside the combustion chamber during the air-fuel mixture intake process.
Providing an auxiliary intake passage, dividing the intake passage into a primary and secondary structure, or arranging a protrusion or valve near the intake valve to create a biased flow of intake air. A structure has been proposed in which the intake passage is divided into two parts, the primary and the secondary, and the primary and secondary throttle valves are arranged close to the combustion chamber.

(Problem to be solved by the invention) However, in the case of the auxiliary intake passage method, even if air or air-fuel mixture is jetted from the auxiliary intake passage into the combustion chamber at high speed, the main intake passage cross-sectional area is not oriented toward high-speed, high-load performance. As a result, in a low load region, that is, a region with low volumetric efficiency, the air-fuel mixture flow velocity is slow, so swirl is weakly generated in the combustion chamber of the overall flow (combined flow of main intake air and sub-intake air). Air is taken in due to the pressure difference with the atmosphere, so the throttle opening is large.
The effect becomes less effective at medium loads or higher where the boost becomes low. Furthermore, due to the influence of the bypass flow rate during idle, the atomization of the fuel during idle may be slightly impaired.

In addition, because the flow velocity of the air flowing through the ventilate part of the carburetor is slow and the relative velocity between the injected fuel and the air flow is slow, sufficient atomization of the fuel is not possible, and a large amount of fuel passes through the intake passage in liquid form and enters the wall. Since the air and fuel are supplied to the combustion chamber in the form of a stream, it is difficult for the air and fuel to have a homogeneous composition, and there is also the problem that the distribution among the cylinders becomes uneven, resulting in poor combustion.

Furthermore, when primary and secondary passages are arranged in the intake pipe, the primary side (low-load side) is generally located far from the engine shaft, so the intake passage is long, and the surface area is It's also big. As a result, in the partial load region, the response during acceleration is poor due to large intake resistance, and the atomization of the fuel in the ventilate is incomplete, causing it to flow through the intake passage in a liquid state as a wall flow, resulting in a lean air-fuel ratio. At the same time, during deceleration, the inside of the intake pipe becomes high negative pressure, so the fuel adhering to the wall evaporates all at once and is sucked into the combustion chamber, resulting in an overrich air-fuel ratio and poor combustion. There is. This becomes even more pronounced during deceleration from the area where the secondary side is operating.

Furthermore, when distributing mixers from one carburetor to multiple cylinders, it is necessary to increase the distance from the throttle valve of the carburetor to the branch to some extent in order to make the mixer distribution uniform. If the length is too short, the flow velocity will be high and the air-fuel mixture will be biased in one direction due to its inertial energy, resulting in poor distribution.
Furthermore, since pressure recovery against drifting is impossible, problems arise, particularly in the slow system becoming unstable.

On the other hand, regarding distribution, when the engine is at partial load, the flow in the intake pipe is complex, and the fuel evaporates due to negative pressure in the intake pipe or heating of the intake air, and the evaporated fuel is distributed to each part by the air flow. The distribution is determined by the supply to the cylinders. Although there is a method of balancing the pressure corresponding to the airflow between cylinders, there are disadvantages such as increased intake resistance.

The present invention has been made in view of the above-mentioned points, and the opening and closing of the throttle valve on the secondary side is controlled by an actuator operated by the distributed negative intake pressure of each cylinder on the primary side. The object of the present invention is to provide a three-valve internal combustion engine that can achieve a balance between each branch, stabilize slow system combustion, and reduce intake resistance.

(Means for Solving the Problems) As a means for solving the above problems, the present invention provides two intake valves (an intake valve 5 on the primary side and an intake valve 6 on the secondary side) and one exhaust valve. In a three-valve internal combustion engine, the fuel supply system is divided into two, a primary side and a secondary side, and both fuel supply systems are provided in the main body of the same carburetor 7, and the intake passage on the primary side is It consists of a primary side intake conduit passage that communicates a primary side intake port 3 provided in the cylinder head 1 with a primary side ventilate 11, and a secondary side intake passage provided in the cylinder head 1. It consists of a secondary side intake port 4 and a secondary side intake conduit that communicates the intake port 4 and the secondary side ventilate 27, and the primary side intake conduit is connected to the secondary side intake. Further, the throttle valve 22 on the primary side is installed in the intake passage on the primary side in close proximity to the ventilary 11 on the primary side, and the throttle valve 44 on the secondary side is formed in the intake passage on the secondary side. The throttle valve 44 is installed in each cylinder in the intake passage on the secondary side in close proximity to the intake port 4 of An actuator 48 that simultaneously closes the throttle valve 44 on the secondary side when the throttle valve 44 increases is connected via an arm 47 and an actuating rod 49, and an actuating spring within the actuator 48 that resists actuation by the negative intake pressure on the primary side. 52 spring force,
The configuration is such that it is set to a value related to the pressure value of the intake negative pressure on the primary side.

(Function) Set the throttle valve position as above,
By arranging the throttle valve for each cylinder and by making the opening and closing of the throttle valve on the secondary side related to the intake negative pressure on the primary side, fuel atomization is promoted, the distribution within the cylinder is uniform, and the air-fuel mixture is The flow rate increases and the generation of swirl is promoted. These factors increase the combustion speed, stabilize combustion, and improve thermal efficiency without impeding performance in high-speed, high-load ranges. It also means that the pressures in each branch of the intake manifold are balanced.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In Fig. 1, 1 is a cylinder head of a four-cylinder engine, 2 is a combustion chamber, 3 is an intake port on the primary side formed in the cylinder head 1, 4 is an intake port on the secondary side formed in the cylinder head 1, 5 is an intake port on the secondary side formed in the cylinder head 1. 6 is a primary intake valve that opens and closes the intake port 3 to the combustion chamber 2, and 6 is a secondary intake valve that opens and closes the opening of the intake port 4 to the combustion chamber 2. The maximum lift amount (maximum valve opening amount) of the primary intake valve 5 due to the camshaft (not shown) is set smaller than the maximum lift amount due to the camshaft (not shown) of the secondary intake valve 6.

In FIGS. 2 and 3, A is an exhaust valve and B is an ignition plug. In the figure, the intake port 4 opens into the combustion chamber 2 in the circumferential direction.
The intake port 3 opens into the combustion chamber 2 in the same direction as the intake port 4 at a position downstream from the intake port 4. Moreover, in FIG. 3, the center of the combustion chamber 2 is O ₁ , the center of the primary intake valve 5 is O ₂ , the center of the spark plug B is O ₃ , the line connecting the centers O ₁ and O ₂ is C, and the center O ₂ , the line connecting O ₃ is D, passing through the center O ₃ , and
The line perpendicular to line D is E, the intersection between line E and the inner wall of combustion chamber 2 is Pc, the line connecting center O ₁ and intersection Pc is F, the intersection between center O ₁ and the inner wall of combustion chamber 2 is Pd, the center Assuming that G is a line connecting _O1 and a point Pd on the inner wall of the combustion chamber 2 on the left side of the intersection Pc, the opening direction of the intake port 4 is set as follows. That is, the spark plug B and the intake port 3 are set so that the angle formed by the lines C and G is 70° and the angle formed by the lines F and G is 30°, and the intake port 3 is set so that the incoming jet flows at the intersection point Pc. ,
It is set to go between PDs.

What is indicated by the reference numeral 7 in FIG. 1 is a carburetor. This carburetor 7 has a first main body 8a and a second main body 8b.
and a throttle body 8c.
, a float chamber 9 , and a float 10 within the float chamber 9 . This carburetor 7 is further provided with a primary side fuel supply system consisting of the following components, and a secondary side fuel supply system located externally and integrally with this primary side fuel supply system. (See Figure 2 for the integral structure). The primary side fuel supply system includes a ventilary 11, a main nozzle 12, and a main jet 13 provided at the bottom of the float chamber 9.
and a fuel well 14, which is a fuel passage that communicates the main jet 13 and the main nozzle 12.
Main air jet 1 opening on the air cleaner side
5 and the air jet 16, an air passage 17 that communicates the main air jet 15 and the main nozzle 12, and the air jet 16 and the main nozzle 1.
2 and the air passage 18 communicating with the air passage 1.
8, and has a main fuel supply system consisting of an adjusting screw 19 that adjusts the opening of that part.

In the figure, 20 is a chiyoke valve provided upstream of the main nozzle 12, and 21 is the main nozzle 12.
A passage 22 provided downstream of the passage 21 is a primary throttle valve mounted in the passage 21. Furthermore, the primary side fuel supply system has bypass port 2.
3, an idle port 24, a passage 25 communicating with these and the air passage 18, and a screw 26 for idle adjustment that adjusts the opening between the idle port 24 and the air passage 18. have In addition, the fuel supply system on the secondary side includes a ventilate 27, a main nozzle 28,
The main jet 29 provided at the bottom of the float chamber 9, the main jet 29 and the main nozzle 28
The fuel well 30 is a fuel passage that communicates with the fuel well 30.
It has a main fuel supply system consisting of a main air jet 31 that opens to the air cleaner side, and an air passage 32 that communicates the main air jet 31 with the main nozzle 28. In the figure, 33 is a passage downstream of the ventilate 27.

The primary-side vent turret 11 is eccentrically provided within the secondary-side vent turret 27. vaporizer 7
is attached to the cylinder head 1 via an intake manifold 34 (see FIG. 2) and an adapter 35. The primary side ventilate 11 communicates with the combustion chamber 2 via the primary side intake passage, which will be described later.
The ventilator 27 on the secondary side communicates with the combustion chamber via an intake passage on the secondary side, which will be described later. The intake passage on the primary side is composed of the intake port 3 and the intake passage on the primary side. ing. Further, the secondary side intake passage is composed of the intake port 4 and the secondary side intake conduit, and this intake conduit is composed of the above-mentioned passage 33, a passage 38 in the intake manifold 34, and a passage 39 in the adapter 35. has been done. Passage 37 is formed within passage 39 and passage 36 is formed within passage 38. 40 is a wall section dividing the passages 37 and 39;
41 is a flow path formed on the side of the passage 36 of the intake manifold 34; 42 is a partition wall that partitions the flow path 41 and the passage 36; 43 is an intake fin that projects from the partition wall 42 toward the inside of the flow path 41; Exhaust gas or engine cooling water is introduced into the flow path 41 .

A secondary throttle valve 44 is installed for each cylinder on the intake port 4 side of the secondary intake guide passage, that is, in a branch portion of the passage 39 that communicates with each cylinder. A plurality of side passages 45 are bored in the partition wall 40 outside the throttle valve 44.
This side passage 45 is connected to the throttle valve 44 of the passage 39 when the throttle valve 44 on the secondary side is fully closed.
The immediately upstream side of the passage 37 is communicated with the passage 37.
Reference numeral 46 denotes a shaft to which the throttle valve on the secondary side is integrally attached, and serves as the center of rotation of the throttle valve 44 on the secondary side. An arm 47 is integrally fixed to this shaft 46 toward the passage 38 side, and an operating rod 49 of an actuator 48 is connected to this arm 47. The negative pressure chamber 48a of the actuator 48 is communicated with a port 51 that opens into the adapter 35 via a passage 50.

The spring force of the spring 52 of the actuator 48 is set as follows. In other words, this spring force corresponds to the pressure (negative pressure) in the passage 37 when the primary throttle valve 22 is fully opened.
The actuating rod 49 is lowered against the pressure, and the throttle valve 44 is set to a value that allows the throttle valve 44 to be opened. 53 is an EGR port provided on the adapter 35. An exhaust source (not shown) is connected to this port 53 via a passage 54 and an EGR valve 55. Note that an exhaust manifold or the like is used as an exhaust source.

Next, the operation of the three-valve internal combustion engine having such a configuration will be explained.

(a) Throttle valves 22 and 4 on the primary and secondary sides
4 is fully closed (during idling) When the throttle valve 22 is fully closed, the fuel in the float chamber 9 is sucked into the passage 25 via the fuel well 14 due to the engine's intake negative pressure, and at the same time, Air from the air cleaner side passes through the air jet 16 and the air passage 18 to the passage 25.
inhaled into the body. At this time, the air upstream of the throttle valve 44 also flows through the bypass port 23.
The air and fuel mixture is then mixed into a mixed fluid in the passage 25 through the idle port 24 and then sprayed into the passage 36 from the idle port 24. This air-fuel mixture absorbs the thermal energy of the cooling water or exhaust gas flowing in the flow path 41, and after its atomization is promoted, it is sucked into the path 37.

On the other hand, at this time, an ultra-lean mixture (super-lean mixture) is generated in the ventilate 27. This air-fuel mixture is injected into the passage 37 through the side passage 45 at high speed. Therefore, the mixture sucked into the passage 37 after atomization has been promoted in the flow passage 41 is agitated by the ultra-dilute mixture on the secondary side that is sprayed from the side passage 45 into the passage 37. ,
Its ultra-fine particle formation is promoted.

In this way, the air-fuel mixture whose atomization and ultra-atomization have been promoted is sucked into the combustion chamber 2 in the circumferential direction through the intake port 3 on the primary side, and a vortex is formed within the combustion chamber 2. be done. At this time, the air around the spark plug B is scavenged by the jet of this air-fuel mixture.

(b) When only the throttle valve 22 on the primary side is operating (partial load region = low volumetric efficiency) When the throttle valve 22 opens from the idling state and the engine's intake negative pressure begins to act on the ventilate 11, the float The fuel in the chamber 9 is transferred to the main jet 13 and the fuel well 14.
The air is sprayed into the ventilator 11 through the air cleaner and mixed with air from the air cleaner side. The air-fuel mixture thus formed is transferred to the throttle valve 2.
When passing through the narrow gap between the engine 2 and the throttle body 8c, the particles are atomized at high speed and then sucked into the combustion chamber 2 through the passages 36, 37 and the intake port 3 on the primary side, just as during idling. be done.

(c) When the throttle valve 22 on the primary side is operated When the throttle valve 22 is opened nearly to the fully open position, the pressure inside the passage 36 on the primary side changes from the negative pressure state when the throttle valve 22 was closed. The value is close to atmospheric pressure. This pressure change passes through the passage 50 to the negative pressure chamber 48a of the actuator 48.
It acts on At this time, the spring 52, which is preset to a force that resists the negative pressure value, expands, and the actuating rod 49 and arm 47
4 throttle valves 44 on the secondary side via
open the valves at the same time.

In this way, the throttle valve 4 on the secondary side
When the valve 4 opens, the fuel sprayed from the main nozzle 28 is mixed with the mixer from the air cleaner side to form an air-fuel mixture in the ventilate 27. This air-fuel mixture is drawn into the passage 39 through the passages 33 and 38, and then passes through the narrow gap between the throttle valve 44 and the adapter 35. When passing through the gap in this manner, the speed is increased to promote atomization, and then the air is sucked into the combustion chamber 2 from the intake port 4 on the secondary side in the circumferential direction. This suction direction is the same direction as the air-fuel mixture sucked into the combustion chamber 2 from the intake port 3 on the primary side, so these two air-fuel mixtures merge to create an even stronger vortex in the same direction in the combustion chamber 2. is formed.

(d) Operation immediately after deceleration Immediately after deceleration, the throttle valves 22 and 44 are closed, so the intake negative pressure in the passage 36 becomes extremely high. Therefore, the fuel adhering to the inner wall surface of the passage 36 instantly evaporates and flows into the combustion chamber 2. At this time, the air-fuel mixture in the passage 36 is extremely rich. However, since this rich mixture particularly occurs near the idle port 24, there is a slight time lag until the rich mixture reaches the passage 37. On the other hand, the ultra-lean mixture in the passage 38 on the secondary side is blown out into the passage 37 from the side passage 45 . Therefore, even if an excessively rich mixture occurs near the idle port 24 immediately after deceleration, this mixture is mixed with an ultra-lean mixture in the passage 37 to form a mixture with an appropriate value. Thereafter, the air is sucked into the combustion chamber 2 through the intake port 3 on the primary side. As a result, stable combustion can be obtained even immediately after deceleration.

(e) Effect of EGR As the engine operates, some of the exhaust gas from the exhaust manifold, etc.
5 into the vicinity of the throttle valve 44 on the secondary side from the port 53, and then into the combustion chamber 2 from the intake port 4 on the secondary side. Since the exhaust gas is introduced into the passage 39 from a place close to the throttle valve 44 on the secondary side, mixing with the air-fuel mixture is improved, and as a result, the combustion temperature is lowered with low EGR and NOx
acts to suppress the production of

(Effects of the Invention) The present invention is a three-valve internal combustion engine that is constructed and operates as described above, but its most significant feature is that the primary throttle valve is located close to the ventilate. The throttle valve on the secondary side is installed in the intake passage on the secondary side, close to the intake port on the secondary side, for each cylinder. An actuator that simultaneously closes each throttle valve on the secondary side when the intake negative pressure in the intake passage on the primary side increases is connected to each of the throttle valves via an arm and an actuating rod. The throttle valve on the secondary side is driven to open and close by the actuator, and the spring force of the spring in this actuator is set to the pressure (negative force) in the passage when the throttle valve on the primary side is fully opened. In contrast, the throttle valve on the secondary side was set to a value that would allow it to open.

This promotes atomization of fuel, makes the distribution uniform in the cylinder, increases the flow rate of the mixture, and promotes the generation of swirl, increasing the fuel speed and stabilizing combustion, which improves the speed and high load range. Thermal efficiency can be improved without interfering with the performance of the The timing of operation of the throttle valve in the side fuel supply system can be made appropriate, and the pressures in each branch of the intake manifold can be balanced.
This makes it possible to stabilize slow combustion and reduce intake resistance.

Volumetric efficiency is improved because the intake valve is dedicated to each of the primary and secondary intake passages. Since the primary side intake passage is covered by the secondary side intake passage, low temperature startability is improved. Furthermore, by forming the primary side intake air conduit within the secondary side intake air conduit, the control configuration can be made compact.

[Brief explanation of drawings]

Figure 1 is a sectional view of an embodiment of the present invention, Figure 2 is a plan view of the main parts of the internal combustion engine shown in Figure 1, and Figure 3 shows the primary and secondary intake ports of the engine shown in Figure 1. FIG. 3 is a layout diagram showing the relationship with a combustion chamber. 1... Cylinder head, 2... Combustion chamber, 3...
Primary side intake port, 4...Secondary side intake port, 5...Primary intake valve, 6...Secondary intake valve, 7...Carburizer, 11, 27...Ventilary, 22, 44...Slot Tutle valve, 25,3
6, 37, 38, 39... passage, 40... bulkhead,
45...Side road.

Claims (1)

[Claims] 1. In a three-valve internal combustion engine with two intake valves and one exhaust valve, the fuel supply system is divided into two, the primary side and the secondary side, and both fuel supply systems are placed in the same carburetor body. At the same time, the primary side intake passage is composed of a primary side intake conduit passage that communicates the primary side intake port provided in the cylinder head with the primary side ventilate, and the secondary side intake passage is It consists of a secondary intake port provided in the cylinder head and a secondary intake conduit that communicates the intake port with the secondary ventilate, and the primary intake conduit is connected to the secondary side. Further, the throttle valve on the primary side is installed in the intake passage on the primary side in close proximity to the ventilate on the primary side, and the throttle valve on the secondary side is formed in the intake passage on the secondary side. The throttle valve is installed in each cylinder in the intake conduit passage on the secondary side in close proximity to the intake port of An actuator that simultaneously closes each throttle valve on the secondary side when increased is coupled via an arm and an actuating rod, and the spring force of an actuating spring resisting the actuation by the negative intake pressure on the primary side in the actuator, A three-valve internal combustion engine characterized in that the pressure is set to a value related to the pressure value of intake negative pressure on the primary side.