JPH01318754A - Rotary throttle valve type carburetor - Google Patents

Abstract

PURPOSE:To improve stability of operation by a method wherein a throttle valve is rotatably fitted into a throttle valve chamber provided perpendicular to an intake air path, and when it rotates, the throttle valve is moved upward by engagement of protrusions formed on the upper part of the valve and a cam in the valve chamber. CONSTITUTION:At the middle of an intake air port 2 which extends through a carburetor main body 1, a throttle valve chamber 3 is provided perpendicular to the path 2. Into this chamber 3, a throttle valve 10 having protrusions 9 at the upper part and a recess 12, which aligns a venturi tube 11 when the throttle valve is completely closed, at the lower end is rotatably fitted. The protrusions 9 are made to come into contact with a cam 14 formed on a shoulder 5 of the chamber 3 so that the throttle valve 10 is moved upward and downward according to the swing of said valve 10 via a throttle lever 22. On the center axis of this throttle valve 10, a jet needle 15 is mounted, and its tip is inserted into a fuel nozzle 8 so that fuel injection amount can be adjusted according to axial movement of the throttle valve 10.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a rotary throttle valve type carburetor that can be widely used in small engines.

<Prior Art and Problems> Conventionally, this type of carburetor has a throttle valve rotatably disposed orthogonal to the intake passage passing through the carburetor body and having a through hole corresponding to the intake passage. The throttle valve is moved in an axial direction as the throttle valve rotates, and a jet needle attached to the throttle valve is moved within a fuel nozzle that is arranged to protrude into an intake passage, thereby controlling the amount of fuel jetted. ing. (Refer to Japanese Utility Model Publication No. 61-21562.) However, since the throttle valve's through hole is aligned with the intake passage when it is fully opened, the throttle valve is opened downward during idling to reduce the amount of fuel jetted. The throttle valve's through hole sinks below the intake passage. In addition, at the idling opening, the volume inside the through hole of the throttle valve becomes larger than the opening of the throttle valve, resulting in a pressure drop, so the fuel flowing out from the fuel nozzle is not completely atomized and the throttle valve It collects at the bottom of the through hole, which is unfavorable for engine operation.

An object of the present invention is to provide a rotary throttle valve type carburetor that improves low-speed operability and maintains stable performance for a long period of time.

<Means for solving the above problems> The rotary throttle valve type carburetor of the present invention is provided perpendicularly to the intake passage, and its bottom is formed at approximately the same position as the bottom of the intake passage, and a shoulder is formed on the open end side. a throttle valve chamber in which a part is formed; a throttle valve accommodated in the throttle valve chamber so as to be slidable in the circumferential and axial directions; at least two or more protrusions protruding from an upper part of a peripheral wall of the throttle valve; two or more cam parts formed on the shoulder part for abutting the protrusion to move the throttle valve up and down; and a recess part formed at the lower end of the throttle valve and matching with the venturi when the throttle valve is fully opened. , is inserted into a main nozzle that is disposed on the central axis of the throttle valve, one end of which is coupled to the throttle valve, and the other end of which is disposed in the carburetor body, and the movement of the throttle valve in the axial direction causes the flow to be removed from the main nozzle. a jet needle for adjusting the fuel injection amount of the
a throttle lever that is rotatably mounted on the rotation center axis of the throttle valve of the carburetor main body, is slidable in the axial direction with the throttle valve, and is integrally coupled with the throttle valve in the rotational direction; and the throttle lever and a compression spring that is disposed between the throttle valve and presses the protrusion toward the cam portion; It is composed of a coil spring that applies a biasing force in the circumferential direction toward the position.

<Operation> According to the above configuration, when the throttle valve is idling open, the volume of the inner chamber of the recess of the throttle valve becomes large compared to the opening formed by the gap between the recess of the throttle valve and the intake passage. A pressure drop occurs, and a portion of the fuel flowing out from the fuel nozzle is not atomized and accumulates at the bottom of the throttle valve chamber, but at this idling opening, the bottom side of the intake path is also slightly opened due to the action of the cam section. This fuel is guided through the bottom wall of the intake passage and quickly supplied to the engine.

Therefore, since fuel does not accumulate at the bottom of the throttle valve chamber, the operating performance of this type of carburetor during idling can be improved.

Further, for moving the throttle valve in the axial direction,
Since the cam part and the protrusion are provided within the carburetor main body and are isolated from the outside, there is little dust or the like adhering to the cam part or the protrusion, and stable fuel metering performance can be obtained over a long period of time.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
It is a top plan view with the cover of the figure removed.

1 is a carburetor main body, through which an intake passage 2 is provided;
A throttle valve chamber 3 is provided in the middle of the intake passage 2 so as to be perpendicular thereto. The bottom of each of the throttle valve chambers 3 is formed substantially on the same plane as the bottom of the intake passage 2, and a shoulder 5 is formed on the open end side. A fuel nozzle 8 is disposed in the carburetor body 1. One end of the fuel nozzle 8 projects from the bottom of the throttle valve chamber 3 into the intake passage 2, and the other end communicates with the fuel chamber 7 via the main jet 6. .

A throttle valve 10 is rotatably arranged in the throttle valve chamber 3 and has a protrusion 9 on the upper part of the peripheral wall and a recess part 12 on the lower end that fits into the venturi part 11 when the throttle valve is fully opened. comes into contact with a cam portion 14 provided on the shoulder portion 5, and moves the front throttle valve 10 up and down as the throttle valve 10 rotates. Further, a jet needle 15 is attached to the throttle valve 10 on its central axis, and the tip of the jet needle 15 is inserted into the fuel nozzle 8.

Therefore, the amount of fuel jetted from the fuel nozzle 8 can be adjusted by moving the throttle valve 10 in the axial direction.

Reference numeral 20 denotes a cover that encloses the throttle valve chamber 3. A throttle lever 22 is rotatably mounted on the cover 20 on the rotation axis of the throttle valve 10, and the throttle lever 22 is axially connected to the throttle valve 10. It is slidable in the direction of rotation, and is integrally connected in the direction of rotation. A compression spring 23 is provided between the throttle lever 22 and the throttle valve 10 to press the protrusion 9 toward the cam portion 14.
is arranged, and the throttle lever 22 and the carburetor main body 1
A coil spring 24 is disposed between the throttle lever 22 and the coil spring 24, which applies a circumferential biasing force to the throttle lever 22 toward the idling opening position. is coupled to the carburetor body 1 or the cover 20.

Therefore, only the throttle valve 10 is moved up and down by the rotation of the throttle lever 22, so even if the position of the operating wire attached to the throttle lever 22 is shifted in the vertical direction, the throttle valve 10 can be pulled up by the wire. This wire will not prevent the throttle valve 10 from moving upward, causing malfunction.

25 is screwed onto the carburetor main body 1, and its tip is connected to the projection 9.
This is an idle screw that adjusts the idling opening degree of the throttle valve 10 by bringing it into contact with the throttle valve 10.

Next, the operation of this embodiment will be explained.

When the throttle lever 22 is in the idling position,
The protrusion 9 of the throttle valve 10 contacts the lowest position of the cam portion 14, and the throttle valve 10 is held at the minimum opening degree. At this time, the jet needle 15 is deeply inserted into the fuel nozzle 8, and the opening of the fuel nozzle 8 is made small to adapt the amount of fuel supplied from the fuel nozzle 8 to idling operation.

Furthermore, during idling, the volume of the recessed interior chamber 16 of the throttle valve 10 becomes extremely large compared to the idling opening, so the flow velocity in this recessed interior chamber 16 becomes slow and a portion of the fuel flowing out from the fuel nozzle 8 is The fuel tends to accumulate at the bottom of the throttle valve chamber 3 without being atomized, but at this idling opening, the bottom side of the intake passage 2 is also slightly opened due to the action of the cam part 14, so this fuel flows from the bottom to the intake passage 2. It is quickly supplied to the engine through the bottom.

Next, when the throttle lever 22 is gradually rotated to open the throttle valve 10, the recessed portion 11 at the bottom of the throttle valve gradually turns toward the intake path 2, increasing the amount of air, and the cam portion 14 opens the throttle valve 10. is completely moved upward, the jet needle 15 is lifted up from the fuel nozzle 8, and the amount of fuel from the fuel nozzle 8 is increased along with the increase in air in the throttle valve 10.

Then, when the throttle valve 10 is fully opened, the protrusion 9
Since the tip of the cam part 14 comes into contact with the uppermost position of the cam part 14, the throttle valve 10 is pulled up to the uppermost position, the recessed part 12 matches the venturi part 11, and the fuel nozzle 8 is held in the most open state and the maximum opening is reached. Supply fuel commensurate with the amount of air.

Furthermore, as shown in FIG. 3, if the shapes of the intake passage 2 and the recessed part 12 of the throttle valve 10 that match the intake passage 2 are varied, the amount of intake air with respect to the amount of rotation and upward movement of the throttle valve 10 can be changed. The engine speed can be changed to accommodate various engine characteristics.

<Effects of the Invention> As detailed above, according to the present invention, the bottom of the throttle valve chamber is formed on substantially the same plane as the bottom of the intake passage, and
A recess that matches the shape of the venturi part is formed at the bottom of the throttle valve, and the opening of the intake passage is adjusted by the rotation and slight upward movement of the throttle valve, so that the inner chamber of the throttle valve closes to the intake passage during idling operation. The fuel accumulated at the bottom of the throttle valve housing hole, which is more depressed, is quickly supplied to the engine through the intake passage, allowing smooth idling operation.

In addition, when the throttle lever rotates, only the throttle valve moves up and down, and the throttle lever does not move up and down, so compared to conventional rotary throttle valve type carburetors in which the throttle valve and lever move up and down together, it requires less operation wire. In addition to greatly relaxing the restrictions on positioning, operability is also improved.

In addition, since the cam part is placed in the throttle valve chamber that is isolated from the outside, there are fewer sliding defects and changes in the amount of movement of the throttle valve due to dust adhering to the cam part, resulting in a stable throttle valve over a long period of time. It is possible to obtain the operational performance of 100% and to perform stable fuel metering.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
FIG. 3 is a top plan view with the cover removed, and FIG. 3 is a vertical cross-sectional view of a main part showing another embodiment of the present invention. 1... Carburetor main body, 3... Throttle valve chamber, 10.
... Throttle valve, 14... Cam part, 15... Jet needle, 22... Throttle lever, 23...
・Compression spring, 24...Coil spring. Patent Applicant Tikei Vaporizer Co., Ltd. Representative Makoto Bando Figure 1 1υ Figure 2 Figure 3

Claims (1)

[Claims] A throttle valve chamber is provided perpendicularly to the intake passage, the bottom of which is formed at approximately the same position as the bottom of the intake passage, and a shoulder is formed on the open end side, and a throttle valve chamber that slides in the circumferential and axial directions onto the throttle valve chamber. a throttle valve that is movably housed; at least two protrusions that protrude from an upper part of the peripheral wall of the throttle valve; and two or more protrusions that are formed on the shoulder and that abut against the protrusions to move the throttle valve up and down. at least one cam part; a recess part formed at the lower end of the throttle valve and mating with the bench lily when the throttle valve is fully opened; a jet needle inserted into a main nozzle disposed in the carburetor body and for adjusting the amount of fuel jetted from the main nozzle by moving the throttle valve in the axial direction; and rotation of the throttle valve of the carburetor body. a throttle lever rotatably mounted on a central axis, slidable in the axial direction with the throttle valve, and integrally coupled in the rotational direction; and a throttle lever disposed between the throttle lever and the throttle valve. a compression spring that presses the protrusion toward the cam portion; and a compression spring that is coupled at one end to the throttle lever and the other end to the carburetor body to bias the throttle lever in the circumferential direction toward an idling opening position. A rotary throttle valve type carburetor including a coil spring that applies force.