JPH0341084Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Industrial application field) This invention is an internal combustion engine (hereinafter referred to as
The invention relates to a variable bench lily carburetor used in engines.

(Prior Art) As shown in FIG. 1, the main part of the variable bench lily carburetor includes a bench lily portion 3 formed by the wall 5a of the intake passage 5 of the carburetor body 1 and the intake passage side end surface 4a of the suction piston 4. , its upstream end 3a
(This is the narrowest part) The area of the suction piston 4 is changed by moving back and forth in accordance with the amount of intake air. Intake air is supplied from an air cleaner (not shown) to the upstream end 3a of the bench lily portion 3.
After passing through the bench lily portion 3, which has a large area, it passes through a throttle valve (not shown) and is sucked into the engine. The wall 5a of the intake passage 5 is located in the bench lily portion 3.
There is a main nozzle 13 protruding from the suction piston 4, and a metering needle 8 is protruded from the intake passage side end surface 4a of the suction piston 4 and is inserted into the main nozzle 13.

In such a conventional variable bench lily vaporizer,
During driving, the suction piston 4 in the intake passage 5 is constantly moving in response to the rapidly fluctuating movement of the accelerator pedal, and is also rattled by engine vibrations, causing the air in the bench lily portion 3 to The intake shape (see the triangular air intake shown in Figure 4) is constantly changing, and as a result, the airflow at the vent lily in the intake passage is constantly changing, and when the airflow changes, turbulence ( eddy currents) and changes in air resistance with the wall surface, etc.
In particular, the wind, which tends to flow along the wall surface due to the change in the eddy current, oscillates and flows from one left and right wall surface to the other left and right wall surface.

However, when the air volume is low and the vortex is relatively stable, such as when idling, the wind flows unevenly along the left and right walls, and as a result,
When the air volume is small, the air volume is deflected to one side of the main nozzle 13, and when the intake air volume is in the intermediate region,
Air flow is controlled by main nozzle 1 due to changes in vortex flow caused by changes in the shape of the air intake in the bench lily.
When the amount of intake air is small at a portion where the area of the intake passage 5 suddenly changes due to the swinging from side to side of 3, the air flow is deflected to one side of the main nozzle 13 as shown in FIG. 2a. When the amount of intake air is large, the air is directed toward the main nozzle 13 as shown in FIG. 2c, and flows on both sides of the main nozzle 13. However, as the amount of intake air increases, the direction of the flow of the intake air does not change continuously from the deflected state to the directed state with respect to the main nozzle 13 in a stable state, but in a certain region along the way, as shown in Fig. 2b. The airflow oscillates from side to side with respect to the main nozzle 13. In this state, the negative pressure in the main nozzle 13 of the carburetor becomes unstable, the air-fuel ratio changes according to the amount of fuel discharged, and the drivability of the engine becomes unstable.

(Purpose of the invention) The object of this invention is to provide a variable bench lily carburetor in which there is no fluctuation in the airflow in the intake passage, that is, an airflow is always directed toward the main nozzle over the entire intake air amount.

In addition, in Japanese Patent Publication No. 38-22753, in a vaporizer having a large bench lily and a small bench lily,
An obstacle that crosses the small bench lily is disclosed as a means for preventing drift of fuel flowing out from the small bench lily during low speed and high speed operation of the engine. A technical idea is disclosed in which this obstruction causes turbulent flow downstream, and the negative pressure caused by the turbulent flow prevents drift, guides the fuel in the radial direction of the small bench lily, and then blows it away with the airflow. is completely unrelated to the present invention described below. In the present invention, by protruding this obstacle to either the left or right upstream of the main nozzle, the airflow is forcibly deflected in order to eliminate fluctuations in the intake airflow, thereby stably pointing towards the main nozzle. The purpose is to obtain airflow.

(Structure of the invention) This invention to achieve the above object is a variable bench lily carburetor having a main nozzle and a variable bench lily part whose area changes with the advance and retreat of a suction piston. , has a configuration in which a rectifying piece that faces the end surface of the suction piston on the intake passage side projects from either the left or right side directly above the main nozzle.

In this way, by protruding a rectifier piece on either the left or right side of the bench lily directly above the main nozzle in the intake passage, the flow of air in the intake passage that swings at the bench lily will be directed to the side where the flow piece is protruding. Because the rectifier pieces act as obstacles and make it difficult to pass, the flow is stable and largely deviated to the side opposite to the protrusion.

(Explanation based on Examples) This invention will be described below based on drawings showing examples. Components that are the same as those shown in FIG. 1 are given the same numbers, and their explanations will be omitted. 3 to 6 show a first embodiment of this invention. In the figure, 2 is a throttle valve, 6 is a suction hole, 7 is a suction chamber, 9 is a main jet, and 10 is a jet section, all of which are known components of a variable bench carburetor. In the first embodiment, between the upstream end 3a of the bench lily portion 3 and the main nozzle 13, the rectifying piece 11 facing the intake passage side end surface 4a of the suction piston 4 is press-fitted into the wall 5a of the intake passage 5, and fixed with screws. It is provided by integral molding or the like to protrude on the right side directly above the main nozzle 13 toward the suction piston 4. As shown in FIG. 5, the cross-sectional shape of the flow regulating piece 11 may be circular, square, airfoil-shaped, rectangular, etc., but airfoil-shaped or rectangular is particularly preferable. Also, rectifying piece 11
The number may be singular or plural.

By providing the above-mentioned rectifying piece 11, FIG.
As shown in ~c, the airflow is forcibly biased by the rectifying piece 11, but by keeping the direction of the flow upstream of the rectifying piece 11 in one direction and allowing extra air to flow in that direction, the main nozzle 13 A stable airflow is created that directs the Therefore, the flow does not fluctuate unstablely as in the conventional case. In other words, the rectifier piece 11 prevents the occurrence of oscillating flow in the carburetor in all regions from low to high intake air volume, stabilizes the airflow in the carburetor, and always provides a forced flow to the main nozzle 13. It has the function of directing people to

7 and 8 show a second embodiment of this invention. In the second embodiment, the rectifying piece 11 is a spring 14
The amount of protrusion of the intake passage 5 from the wall 5a changes depending on the pressure (static pressure) of the intake air. That is, in a region where the amount of intake air is low (low flow velocity), the static pressure is large, so the amount of protrusion is small, and in a region where the amount of intake air is large, the amount of protrusion is large.

(Effects of the invention) Since this invention has the above-mentioned configuration, it prevents the occurrence of oscillating flow over the entire range of the amount of air taken into the carburetor, and directs a stable airflow toward the main nozzle. As a result (a) fluctuations in the air-fuel ratio are reduced, improving engine operating performance.

(b) Since fluctuations in the air-fuel ratio are small, the air-fuel ratio can be set close to the misfire point of the engine. In other words, it can be set lean. As a result, improved fuel efficiency, exhaust gas purification, and simplification of the exhaust gas purification system are achieved.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional front view of the main parts of a conventional variable bench lily carburetor. In Figure 2, a, b, and c show the state of the intake air flow near the main nozzle of a conventional variable bench lily carburetor, where a shows the state in the low air flow region and c shows the state in the high air flow region. , b indicates the oscillation state of the airflow in the middle of the high and low air flow rate regions, respectively. FIG. 3 shows a longitudinal sectional front view of the first embodiment of this invention. FIG. 4 shows a Q view of FIG. FIG. 5 shows a modification of the cross-sectional shape of the main part of this invention. Figure 6 shows the state of the intake air flow near the main nozzle of the variable bench lily carburetor implementing this invention, where a shows the state at low air flow rate, c shows the state at high air flow rate, and b shows the state at high air flow rate. indicates the state in the intermediate region between the high and low air flow regions, respectively. FIG. 7 shows a longitudinal sectional front view of the main parts of the second embodiment of this invention. 8th
The figure is a view from P in FIG. 7. 1... Carburetor body, 3... Bench lily part, 3a
...Upstream end, 4...Suction piston, 4a
...Intake passage side end surface, 5...Intake passage, 5a...
Wall, 8...metering needle, 11...straightening piece, 13...main nozzle.

Claims (1)

[Scope of utility model registration request] As the suction piston moves forward and backward in response to the amount of intake air flowing through the intake passage in the carburetor body, the area of the bench lily provided in the intake passage changes, and the suction piston protrudes from the end face of the suction piston on the intake passage side. The distance between the metering needle installed and engaged in the main nozzle and the main nozzle changes, and the amount of fuel supplied from the main nozzle to the intake passage changes in proportion to the amount of intake air. A variable bench lily carburetor of the type, wherein a rectifying piece for forcibly biasing the air flow between an upstream end of the carburetor bench lily portion and the main nozzle is provided on an end surface of the suction piston on the intake passage side. A variable bench lily carburetor, characterized in that the variable bench lily carburetor is opposed to the main nozzle and protrudes from either the left or right side directly above the main nozzle.