JPS58202338A - Throttle valve device for carburetor - Google Patents

Abstract

PURPOSE:To reduce the turbulence of a fuel-air mixture flow and stabilize the combustion as well as to secure good accelerability, by installing an auxiliary throttle valve, which closes the upside of a suction path at less than the specified opening value of a throttle valve, in a butterfly type throttle valve for a carburetor. CONSTITUTION:An auxiliary throttle valve 16 is rotatably coupled with a backside at the downstream side of a butterfly type throttle valve 4 installed in a suction path 2 of a carburetor by means of a fulcrum shaft 18 in parallel with a valve shaft 15. Since a resilient coil spring 19 energizing the auxiliary throttle valve at the valve closing side is installed between the auxiliary throttle valve 16 and the butterfly type throttle valve 4, this auxiliary throttle valve 16 is seated at a step part 20 at a fixed angle apart from the backside of the throttle valve 4 and closes half the upside of the suction parth 2 the while the throttle valve 4 is closed to the idle opening range. The lower half part of the suction path alone is opened till the throttle valve 4 and the auxiliary throttle valve 16 come to be overlapped whereby a fuel-air mixture thus becomes a stable, solitary flow. At the low opening region of the throttle valve, the opening area increment rate of the suction path to the throttle valve opening increment is small so that too much rarefaction of the fuel-air mixture can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a throttle valve device for a carburetor, which includes a butterfly type throttle valve in an intake passage.

Conventional butterfly-type throttle valves are fixed to a rotatable valve shaft that cuts through the center of the intake tract, and when the valve is opened, the upper and lower portions of the intake tract are simultaneously opened. Therefore, in the low opening range where the inclination angle of the throttle valve with respect to the center line of the intake tract is extremely large, when the air-fuel mixture flowing through the intake tract passes through the throttle valve, the flow is largely divided under -L, and after passing through the Since they merge again while colliding violently, the disadvantage is that the flow is likely to become turbulent.
It becomes a country that makes P-fired unstable and increases fuel consumption rate.

In addition, with conventional models, the ratio of increase in the opening area of the intake passage with respect to the increase in throttle valve opening is particularly large in the low opening range of the throttle valve, so when the throttle valve is suddenly opened for engine acceleration, , opening the intake tract too early and diluting the mixture,
It also has the disadvantage of easily impairing acceleration.

The present invention has been proposed in view of the above, and includes a sub-throttle valve attached to the throttle valve, and when the throttle valve is opened, only the lower part of the intake passage is opened when the throttle valve opens less than a predetermined opening, and when the throttle valve opens more than the predetermined opening, air is taken in. At the stage where the upper and lower parts of the airway are opened (so that the air mixture flow is divided into upper and lower parts by the throttle valve, the angle of inclination of the throttle valve with respect to the center line of the intake airway decreases, so that the air mixture flow is not disturbed significantly. In addition, in the 11-head region with a low throttle valve opening, the intake tract opens [1] in response to an increase in throttle valve opening.
It is an object of the present invention to provide a front = C throttle valve device which can suppress the rate of increase in area to a small value and thereby eliminate all the drawbacks of the conventional ones.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. In FIG. 1, an engine E has a combustion chamber C, an intake port I for introducing a mixture into the combustion chamber It has a defecation port Ex that leads out exhaust gas from C, and these intake and exhaust ports [.

The EAi intake and exhaust valves V i and Va are opened and closed, respectively.

This engine E is equipped with a carburetor Ca that produces the above-mentioned air-fuel mixture.
is installed. The illustrated carburetor Ca is of a variable venturi type, and an intake passage 2 formed in the carburetor body 1 and communicating with the intake port I has a choke on the upstream side across a venturi portion 2α in the center thereof. Valve 3, throttle valve 4 on the downstream side
are arranged respectively.

The venturi portion 2α is provided with a piston valve 5 that extends through its upper wall and can open and close the venturi portion 2α. This piston valve 5 has a venturi portion 2α at the lower limit.
Allow the small bench lily's to remain without completely closing the lily. A jet needle 6 is attached to the piston valve 5 and projects from its lower end surface, and is inserted into a main fuel nozzle 7 that opens at the bottom surface of the venturi portion 2α. This nozzle 7 is inside the throttle valve 4.

Oil is injected in a high opening range, and a mixture suitable for high-speed operation is created in engine E from the fuel and intake air.

A pressure receiving piston 5α having a larger diameter than the piston valve 5 is integrally connected to the upper end of the piston valve 5, and this pressure receiving piston 5α is slid onto a valve cylinder 9 fitted to the upper part of the carburetor main body 1.
The interior is divided into an upper negative pressure chamber 41 and a lower atmospheric pressure chamber 11. A balance spring 12 for biasing the piston valve 5 in the downward direction is accommodated in the negative pressure $10, and the chamber 1o communicates with the venturi portion 2a through a negative pressure introduction hole 13 formed in the piston valve 5. Therefore, when the intake air amount of the engine increases beyond the value, the negative pressure of the venturi part 2α that increases accordingly is introduced into the negative pressure chamber 1o, and the pulling force of the pressure receiving piston 5α due to the negative pressure and the balance spring 12 The piston valve 5 is opened until the depressing force is balanced by the force, and at the same time the jet needle 6 is pulled up.

Further, a low-speed fuel nozzle 14 is provided on the bottom surface of the intake passage 2 and opens near the throttle valve 4 located at the idle opening.

This nozzle 14 injects oil in a low opening range of the throttle valve 4, and creates a mixture of fuel and intake air suitable for low-speed operation of the rear engine E.

The throttle valve 4 is configured in a butterfly type, and is therefore rotatably supported by the carburetor body 1 and fixed to a valve shaft 15 that crosses the center of the intake passage 2 . A sub-throttle valve 16 is attached to this throttle valve 4 .

This sub-throttle valve 16 will be described in detail with reference to FIGS. 2 and 3. A pair of branch pieces 17, 17 are protruded from the back surface of the throttle valve 4 facing the downstream side of the intake passage 2. These branches 17
, 17, an auxiliary throttle valve 1-6 for opening and closing the road half of the intake passage 2 is rotatably connected to a support shaft 18 parallel to the valve shaft 15.
Further, a torsion coil spring 19 is provided between the sub-throttle valve 16 and the throttle valve 4 to bias the sub-throttle valve 16 toward the valve closing side. This spring 19
The force of is set to be weaker than the force of a return spring (not shown) that urges the valve shaft 15 in the valve closing direction.
Its tip has a length that protrudes upward from the upper edge of the throttle valve 4, and on the other hand, the earth wall of the intake passage 2 has a certain distance downstream of the intake passage 2 from the throttle valve 4 located at the idle opening. The concave stepped portions 20 are spaced apart from each other and have a shape 1. - The tip of the sub-throttle well 16 is seated on this stepped portion 20 as a valve seat.

Next, to explain the operation of this embodiment, FIGS. 1 and 2 show a state in which the throttle valve 4 is closed to the idle opening degree. The stepped portion 2 is moved by the force of the spring 19 at a certain angle to the downstream side of the intake passage 2.
0, thereby blocking the upper half of the intake passage 2. From this state, if the valve shaft 15 is rotated clockwise to increase the opening of the throttle valve 4, the throttle valve 4 and the sub-throttle valve 16 will open.
Since the sub-throttle valve 16 continues to close the upper half of the intake passage 2 until the two overlap, only the lower half of the intake passage 2 is opened. In such a low opening range of the throttle valve 4, all the air-fuel mixture created in the intake passage 2 passes through the lower part of the throttle valve 4 and is taken into the engine E, so this air-fuel mixture is relatively stable and homogeneous. It shows the flow of

After the throttle valve 4 and the sub-throttle valve 16 overlap, if the opening degree of the throttle valve 4 is further increased, the throttle valve 4 becomes the sub-throttle valve 1 as shown in FIG.
6 to separate it from the stepped portion 20 and open the upper half of the intake passage 2 as well. In such a medium or high opening range of the throttle valve 4, the air-fuel mixture drawn in the intake passage 2 is divided so as to pass through the upper and lower parts of the throttle valve 4, and after passing through, the mixture is reunited. However, at this stage, the throttle valve 4 and the σ sub-throttle valve 16 increase (decrease) the inclination angle θ with respect to the center line of the intake passage 2, so that the flow of the air-fuel mixture is They are not divided into large parts, and therefore, after merging, there is no major disturbance in the flow.

When the throttle valve 4 is rotated to the fully open position as shown in FIG. 5, the throttle valve 4 and the sub-throttle valve 16 are aligned with the center line of the intake passage 2.
Both valves 4 and 16 work together to perform the function of a rectifying cylinder and stabilize the flow of the air-fuel mixture1.As described above, according to the present invention, the sub-throttle valve is attached to the throttle valve, and the throttle valve is When opening the valve, if the opening of the throttle valve is less than the predetermined opening, only the lower part of the intake passage is opened, and the predetermined opening - L
Since the upper and lower parts of the intake duct are opened, the angle of inclination of the throttle valve with respect to the center line of the intake duct decreases when the air mixture flow is divided into upper and lower parts by the throttle valve, so the air mixture flow is not disturbed significantly. Therefore, it is possible to stabilize the properties of the air-fuel mixture from a low opening to a high opening of the throttle valve, thereby improving the combustion of the air-fuel mixture and reducing the fuel consumption rate.

In addition, in the low opening region of the throttle valve, only the lower part of the intake duct is opened, so the rate of increase in the opening area of the intake duct with respect to the increase in the opening of the throttle valve can be suppressed to a small value. It is possible to prevent the air-fuel mixture from becoming excessively lean due to the opening, and improve the acceleration performance of the engine.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention, and Figure 1 is a longitudinal cross-sectional side view of a carburetor equipped with the device of the present invention and a part of the engine to which it is installed. An enlarged view of the main part in Figure 1 shows the idle opening state of the throttle valve, and Figure 3 shows the u in Figure 2.
FIG. 4 is an operation diagram showing the throttle valve in the middle open state, and FIG. 5 is an operation diagram showing the throttle valve in the fully open state. Ca... Carburetor, 2... Intake path, 4... Throttle valve, 16... Sub-throttle valve Patent applicant Honda Motor Co., Ltd. Figure 4 Figure 5

Claims (1)

[Scope of Claims] ■ A butterfly-type throttle valve (4) provided in the intake path (2) of the carburetor (α) is provided with A throttle valve for a carburetor, which is equipped with a sub-throttle valve (16) that closes the upper part and then opens the upper part of the intake passage (2) together with the throttle valve (4) when the opening degree exceeds a predetermined opening degree. Device. (2) The throttle valve device for a carburetor according to claim 0, wherein the sub-throttle valve (16) has a length that projects above the tenth point of the throttle valve (4).