JPS6121559Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an intake system for an internal combustion engine, and in particular improves the bridging characteristics at the time of transition from primary to secondary in a dual intake internal combustion engine, and prevents wall flow of fuel in an internal combustion engine. This invention relates to an air intake device.

In a dual-intake internal combustion engine that has a primary intake passage for low loads and a secondary intake passage for high loads, in order to make the transition from the primary to the secondary intake smooth, conventionally the acceleration pump discharge characteristics and the throttle This goal was achieved by changing the interlocking characteristics, etc. However, when dealing with the acceleration pump discharge characteristics, it increases the discharge amount per stroke compared to a normal engine, which is technically a solution, but it worsens the fuel economy and reduces the amount of harmful components emitted from the exhaust. It has the disadvantage of increasing In addition, when dealing with the throttle interlocking characteristics, it is possible to make the connection smooth by setting the opening timing of the secondary side throttle valve earlier, but this does not mean that the primary intake passage for low loads is sufficiently This has the disadvantage that it cannot be operated and the original effect of the dual intake engine cannot be demonstrated.

Furthermore, in a dual intake engine, the intake flow velocity in the primary intake passage for low loads is sufficiently high and can prevent fuel from forming into a wall flow, but the intake flow velocity in the secondary intake passages for high loads is high enough to prevent fuel from forming into a wall flow. Due to the large diameter of the passageway, the flow rate decreases and wall flow of fuel occurs. As a result, fuel economy deteriorated and smooth drivability was hindered.

Therefore, the purpose of this invention was to create an intake system for an internal combustion engine that would smooth the transition from the primary to the secondary, improve driver performance, improve fuel economy, and purify the exhaust gas. It is in.

In the figure, 2 is the cylinder head, 4 is the combustion chamber, 6 is the intake valve, 8 is the intake port, 10 is the exhaust valve, 12 is the spark plug, 14 is the primary intake passage for low load, and 16 is the secondary intake passage for high load. The intake passage 18 is a throttle body. The secondary intake passage for high load 1
A secondary throttle valve 20 that swings open and close around a shaft 19 is provided at the throttle body 18 position of No. 6.
A fuel reservoir 22 is formed downstream of the next throttle valve 20. The fuel reservoir portion 22 is formed by a concave groove that is a smooth groove having a diameter larger than that of the secondary intake passage 16, and the radial direction of this annular groove is positioned approximately at right angles to the intake air flow direction.

Next, the effect will be explained.

In the medium load range where the secondary throttle valve 20 starts to open, the intake flow rate is low, and therefore the intake flow velocity is slow, and part of the fuel supplied from the carburetor becomes a wall flow and flows into the secondary intake passage 16. is directed toward the combustion chamber in four directions. However, in this invention, since a concave groove is provided as a fuel reservoir 22 on the downstream side of the secondary throttle valve 20 at a substantially right angle to the intake flow, the fuel that has become a wall flow enters the fuel reservoir 22. Once stored. For this reason, most of the wall flow flows into the combustion chamber 4.
The flow inside is blocked.

Further, the fuel stored in the fuel reservoir 22 is taken out by the intake air flow flowing through the secondary intake passage 16, and is scattered into the secondary intake passage 16 by a so-called draining action and becomes agglomerated. Ru. This granulation phenomenon also occurs noticeably during transition from primary to secondary. In other words, when the secondary throttle valve 20 opens from the fully closed state, the fuel stored in the reservoir 22 is atomized and sucked into the combustion chamber 4 due to the sudden movement of intake air, so that during the connection It is possible to prevent dilution of the intake air, and it is possible to make the connection characteristics smooth.

Note that, unlike the above embodiment, the fuel reservoir is
For example, a large number of hemispherical recesses may be arranged in parallel in an annular band shape. In other words, the fuel reservoir has only to have a structure that can stop wall flow and temporarily store the fuel.

As is clear from the above detailed description, according to this invention, the wall flow generated in the secondary intake passage 16 can be blocked in the fuel reservoir 22, so that the fuel flows into the combustion chamber in a liquid state. Never. Furthermore, when the secondary throttle valve is opened, the fuel temporarily stored in this fuel reservoir is taken out by the intake air flow flowing through this passage and becomes agglomerated. Therefore, when the secondary throttle valve 20 is opened from the fully closed state, the fuel in this reservoir is vaporized, which prevents dilution of the fuel during connection and improves the responsiveness of the fuel.

Therefore, it is possible to improve combustion conditions, ensure smooth drivability, improve fuel economy, and purify exhaust gas. In addition, the presence of this fuel reservoir can prevent the high heat in the combustion chamber from reaching the vicinity of the secondary throttle valve, and can prevent vapor lock due to vaporization of fuel in the secondary slow fuel passage. This also has the effect of reducing deterioration in sealing performance due to thermal distortion of the secondary throttle valve.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of the main part of an engine showing an embodiment of this invention, and FIG. 2 is a schematic plan view of the engine. In the figure, 14 is the primary intake passage for low load;
6 is a high-load secondary intake passage, 20 is a secondary throttle valve, and 22 is a fuel reservoir.

Claims (1)

[Scope of utility model registration request] In a dual intake internal combustion engine having a primary intake passage for low loads and a secondary intake passage for high loads, an annular band-shaped fuel reservoir is provided in the secondary intake passage for high loads downstream of the secondary throttle valve. An intake system for an internal combustion engine characterized by: