JPH0511214B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a carburetor that controls the concentration and amount of air-fuel mixture supplied to an engine, and particularly relates to a throttle valve guide connected to an intake passage passing through the carburetor body. This invention relates to a sliding throttle valve type carburetor in which a sliding throttle valve is movably disposed within a cylinder.

[Conventional technology]

Conventionally, a commonly used sliding throttle valve type carburetor is provided with a throttle valve guide tube that opens upward and is connected to an intake path that passes through the carburetor body, and a throttle valve guide tube that slides into the throttle valve guide tube is provided. The throttle valve is arranged in a sliding manner so that it can be moved freely.The driver pulls the accelerator wire upward to open the intake passage by pulling the sliding throttle valve upward.On the other hand, when the throttle valve is blocked, the driver can press the accelerator. Generally, by loosening the wire, the spring force of the throttle valve return spring pushes the sliding throttle valve downward to close the intake passage.
The structure of this sliding throttle valve is generally cylindrical or rectangular.

In the case of a cylindrical valve, the outer part of the cylinder is guided by the throttle valve guide cylinder,
In the rectangular type, the rectangular flat plate portion is guided by the groove of the flat throttle valve guide cylinder.

[Problem to be solved by the invention]

In such a sliding throttle valve type carburetor, when the engine is suddenly decelerated from a high-speed operating state, the sliding throttle valve is moved in the closing direction by the spring force of the throttle valve return spring by loosening the accelerator wire. However, in such a state, the engine still maintains a high rotational speed due to inertia. Therefore, an extremely large intake passage negative pressure acts on the end face of the sliding throttle valve on the engine side. For this reason, it has been considered to strengthen the throttle valve return spring for returning the sliding throttle valve to increase the return force, but this increases the opening operation force of the accelerator wire, which is not preferable in terms of operability. This phenomenon occurs in a multiple sliding throttle valve type carburetor that uses multiple single carburetors, and the sliding throttle valve has a rectangular shape and the contact with the throttle valve guide cylinder is flat. Furthermore, it appears more prominently when the intake duct diameter is large.

[Means to solve the problem]

The sliding throttle valve type carburetor of the present invention has been developed in view of the above-mentioned problems, and its purpose is to improve the blocking performance of the sliding throttle valve during sudden engine deceleration. In order to achieve this, the sliding throttle valve is composed of a main throttle valve and a sub-throttle valve. A circular concave portion is formed from one side of the sub-throttle valve toward the other side on the downstream side of the intake tract.Meanwhile, the sub-throttle valve is inserted into the circular concave portion of the main throttle valve on one side of the upstream side of the intake tract. A circular insertion protrusion is formed, and a flat sub-throttle valve guide part capable of opening and closing the intake passage is formed on the other side of the insertion protrusion on the downstream side of the intake passage, and a sub-throttle valve guide part is formed in the circular recess of the main throttle valve. By inserting the insertion protrusion of the throttle valve, a pressure receiving chamber is formed by the circular recess and the insertion protrusion, and a sliding throttle valve is integrally formed. The sliding throttle valve is connected to the intake passage on the engine side via the pressure introduction hole, and the flat plate-shaped main throttle valve guide part of the main throttle valve is connected to the upstream groove part of the throttle valve guide tube, and the flat plate-shaped main throttle valve guide part of the main throttle valve is connected to the upstream groove part of the throttle valve guide tube. The sub-throttle valve guide portion is disposed within the throttle valve guide cylinder and slidably in a downstream groove portion on the downstream side of the upstream groove portion.

[Effect]

During rapid deceleration of the engine, when the sliding throttle valve is rapidly biased in the closing direction and enters a low opening state, an extremely large intake tract negative pressure is generated in the intake tract downstream of the sliding throttle valve. According to this, the flat plate-shaped sub-throttle valve guide section that opens into the intake tract of the sub-throttle valve is for suction to the downstream side (engine side), while the large negative pressure in the intake tract mentioned above is caused by the main throttle valve. Since the negative pressure is introduced into the pressure receiving chamber formed by the valve and the sub-throttle valve through the negative pressure introduction hole, the flat plate-shaped sub-throttle valve guide portion of the sub-throttle valve is pressed against the downstream groove portion of the carburetor main body. The force is caused by the negative pressure in the intake passage applied to the back of the sub-throttle valve in the pressure receiving chamber acting in the opposite direction to the suction toward the downstream side (engine side) of the sub-throttle valve. The force with which the valve guide portion is pressed against the downstream groove portion of the carburetor main body can be reduced. This also makes it possible to improve the dynamic characteristics of the sliding throttle valve.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sliding throttle valve type carburetor according to the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes, and a throttle valve guide cylinder 3 opens above the middle part of the intake passage 2. In this embodiment, the sliding throttle valve, which will be described later, is rectangular and is guided by flat guide portions (described later) at both ends. A downstream groove part 3B is formed downstream of the side groove part 3A (on the right side in the figure), and these upstream groove part 3A and downstream groove part 3B straddle the intake passage 2 in the vertical direction in FIGS. 1 and 2. It is drilled in

A float chamber main body 4 is disposed at the lower part of the carburetor main body 1, and a float chamber 5 is formed by the lower concave portion of the vaporizer main body 1 and the float chamber main body 4. A float F is disposed within the float chamber 5, and a constant liquid level is always formed within the float chamber 5 by operating a float valve that opens and closes a valve seat disposed within the fuel passage. A needle jet 6 opens in the intake passage 2, a mixing nozzle 7 and a main jet 8 are connected to the needle jet 6, and the main jet 8 is submerged below the constant liquid level in the float chamber 5.

A sliding throttle valve 9 is movably disposed within the sliding throttle valve guide cylinder 3. This sliding throttle valve 9 will be explained in detail with reference to the drawings. The sliding throttle valve 9 is the main throttle valve 10
and the sub-throttle valve 11.

Hereinafter, the terms "upstream side" and "downstream side" are based on the airflow flowing through the intake duct 2. For example, in Fig. 1, the air flows from left to right in the intake duct 2, with the left side being the upstream side and the right side being the downstream side. becomes. The air cleaner side corresponds to the downstream side, and the engine side corresponds to the downstream side.

The main throttle valve 10 has a main throttle valve guide part 1 in the form of a flat plate that can open and close the intake passage 2 on one side of the upstream side of the intake passage.
0A, and in order to form a pressure receiving chamber, which will be described later, from one side to the other side on the downstream side of the intake passage, a circular recess 1 is formed.
0B is drilled. The flat main throttle valve guide part 10A is disposed in the upstream groove part 3A of the throttle valve guide tube 3 as described above, and furthermore, the flat main throttle valve guide part 10A is particularly located at the downstream end face 10C.
The sliding surface between the upstream groove portion 3A and the upstream groove portion 3A slides through the friction reducing member R. The friction reducing member R may be any member that reduces the frictional force on the sliding surface, and specifically, a roller or a bearing rotatably supported on the main throttle valve guide 10A of the main throttle valve 10 is used. .

On the other hand, a circular insertion protrusion 11A that is inserted into the circular recess 10B of the main throttle valve 10 is formed on one side of the upstream side of the intake path of the sub throttle valve 11, and the other side of the upstream side of the intake path is formed with a circular insertion protrusion 11A. A flat sub-throttle valve guide portion 11B that opens and closes is formed. This sub-throttle valve guide portion 11B is arranged within the downstream groove portion 3B of the carburetor main body 1.

Then, by inserting the insertion protrusion 11A of the sub-throttle valve 11 into the circular recess 10B of the main throttle valve 10, the flat plate-shaped sub-throttle valve guide of the sub-throttle valve 11 is inserted into the circular recess 10B and the insertion protrusion 11A. A pressure receiving chamber 12 is formed at the back of the portion 11B. Further, in order to improve the pressure holding characteristics of the pressure receiving chamber 12, a sealing member S may be disposed on the insertion protrusion 11A. A negative pressure introduction hole 11C formed in the sub-throttle valve 11 is provided in the pressure-receiving chamber 12 to introduce the negative pressure in the intake passage downstream of the sub-throttle valve 11 (on the engine side). Reference numeral 13 denotes a throttle valve lever operated by the driver, the end of which is mechanically connected to the operating groove 10D of the main throttle valve 10 of the sliding throttle valve 9 by means of rollers or the like.

Further, 15 is a throttle valve return spring that applies a biasing force in the closing direction to the sliding throttle valve 9, and 16 is a jet needle that is integrally attached to the sliding throttle valve 9 and inserted into the needle jet 6. It is.

Next, to assemble the sliding throttle valve 9, first insert the insertion protrusion 11A of the sub-throttle valve 11 into the circular recess 10B of the main throttle valve 10, and then
form. According to this, a flat main throttle valve guide section 10A is formed on one side surface on the upstream side, and a flat sub throttle valve guide section 11B is formed on the other side surface on the downstream side. A pressure receiving chamber 12 is formed at the back of the sub-throttle valve guide portion 11B by the circular recess 10B and the insertion protrusion 19A. When the sliding throttle valve 9 is at a low opening, the effective pressure receiving area of the sub-throttle valve guide portion 11B of the sub-throttle valve 11 with respect to the intake passage 2 on the engine side is It is preferable that the area is larger than the effective pressure receiving area applied to the back.

The sliding throttle valve 9 configured as described above is disposed within the throttle valve guide tube 3 of the carburetor main body 1. At this time, in particular, the flat main throttle valve guide portion 10A of the main throttle valve 10 is The flat plate-shaped sub-throttle valve guide part 11B of the sub-throttle valve 11 must be disposed in the upstream groove part 3A and the throttle valve guide cylinder 3 in the downstream groove part 3B.

In this state, the main throttle valve 10 and the sub-throttle valve 11 open and close the intake passage 2 of the sliding throttle valve 9 because the insertion protrusion 11A of the sub-throttle valve 11 is inserted into the circular recess 10B of the main throttle valve 10. During operation, the main throttle valve 10 and the sub-throttle valve 11 can operate synchronously and integrally.

Next, to explain its function, during engine operation with a constant opening of the sliding throttle valve 9, or during acceleration and normal deceleration operation in which the sliding throttle valve 9 is gradually closed, the downstream side of the sliding throttle valve 9 is No particularly large intake tract negative pressure is generated in the side intake tract 2. Therefore, the sliding throttle valve 9 is not sucked downstream and the sub-throttle valve guide portion 11B is not strongly sucked and pressed against the downstream groove portion 3B of the throttle valve guide tube 3, so that the driver's action against the main throttle valve 10 is prevented. The opening/closing operation is immediately transmitted to the sub-throttle valve 11, and the operation can be performed extremely smoothly.

Next, looking at the case of rapid deceleration operation in which the sliding throttle valve 9 is suddenly closed from a high-speed operating state of the engine with the sliding throttle valve 9 opened to a high opening, the sliding throttle valve 9 is closed until the intermediate opening range. Since there are relatively few openings to the intake passage 2, the effect of negative pressure in the intake passage is small and can be easily restored. However, when the sliding throttle valve 9 returns to the low opening range and attempts to block the intake passage 2, the engine still rotates at a high speed due to inertia, resulting in a high intake passage negative pressure inside the intake passage 2. is occurring. With the conventional type, in such a situation, the suction force to the downstream side of the sliding throttle valve 9 sometimes acts and the return thereof lacks smoothness, but the sliding throttle valve type vaporizer according to the present invention According to the document, the opening of the sub-throttle valve 11 to the intake passage 2 on the engine side, that is, the sub-throttle valve guide 1
1B, a rightward suction force acts on the suction force toward the downstream side (engine side), but this intake passage negative pressure is also introduced into the pressure receiving chamber 12 via the negative pressure introduction hole 11C.

According to this, since the back part of the sub-throttle valve 11, that is, the insertion protrusion 11A opens in the pressure receiving chamber 12, a suction force is generated in the back part of the sub-throttle valve 11 in the left direction in the figure. Therefore, the sub-throttle valve 11, which receives high intake tract negative pressure on the downstream side (engine side), is affected by the suction force in the left direction generated at its back and the auxiliary throttle valve guide portion of the auxiliary throttle valve 19 that opens into the intake tract on the engine side. It will be biased with a pressing force equal to the difference between the rightward suction force generated at 11B and the rightward suction force.

In this embodiment, as described above, the sub throttle valve 11
The sub-throttle valve guide part 1 for the intake passage 2 on the downstream side of
The effective pressure receiving area of 1B is the sub-throttle valve 11 of the pressure receiving chamber 12.
Since the effective pressure-receiving area is larger than the effective pressure receiving area applied to the back of the sub-throttle valve 11, a suction force to the downstream side (engine side) equal to the difference is applied to the sub-throttle valve guide portion 11B of the sub-throttle valve 11.

Therefore, in the sliding throttle valve 9, the sub-throttle valve guide portion 11B of the sub-throttle valve 11 is only biased and held in the downstream groove portion 3B of the sliding throttle valve guide cylinder 3 with a slight pressing force. The sliding throttle valve 9 is not attracted to the sliding throttle valve guide cylinder 3 during sudden deceleration operation.

On the other hand, in the case of the main throttle valve 10, especially the pressure receiving chamber 1
2 is sucked toward the engine side (right side in the figure) by the negative pressure introduced into the intake passage, and this is caused by the sliding surface between the flat main throttle valve guide 10A and the upstream groove 3A of the carburetor body It tends to increase with respect to the sliding friction force. However, in the present invention, since a friction reducing member R such as a roller or a bearing is arranged on the sliding surface, the return force of the main throttle valve 10 is also reduced during such deceleration operation.

Specifically, as shown in FIG. 4, the operating force can be reduced to less than half compared to conventional carburetors.

Note that if the sliding throttle valve does not need to suppress the amount of leakage from the sliding throttle valve to the engine at a low opening, the effective By making the effective pressure receiving area equal to or smaller than the effective pressure receiving area applied to the back of the sub-throttle valve 11 in the pressure-receiving chamber 12, the sub-throttle valve can be positively lifted from the throttle valve guide cylinder, and its return force can be increased. It can be reduced.

〔Effect of the invention〕

As described above, according to the sliding throttle valve type carburetor of the present invention, the sliding throttle valve is composed of a main throttle valve and a sub-throttle valve, and the main throttle valve is arranged on one side of the upstream side of the intake path. A flat plate-shaped main throttle valve guide part that can open and close the intake passage is provided, and a circular concave part is formed from one side to the other side on the downstream side of the intake passage. A circular insertion protrusion that is inserted into the circular recess of the main throttle valve is formed on one side, and a flat sub-throttle valve guide part that can open and close the intake passage is formed on the other side downstream of the insertion protrusion. By inserting the insertion protrusion of the sub-throttle valve into the circular recess of the main throttle valve, the circular recess and the insertion protrusion form a pressure receiving chamber and integrally form a sliding throttle valve. This pressure receiving chamber is connected to the intake passage on the engine side from the sliding throttle valve through a negative pressure introduction hole drilled in the sub-throttle valve, and the flat main throttle valve guide part of the main throttle valve is connected to the throttle valve. The flat plate-shaped sub-throttle valve guide part of the sub-throttle valve is placed in the upstream groove part of the guide cylinder so that it can slide freely in the downstream groove part downstream of the upstream groove part. The negative pressure generated in the intake tract is applied to the back of the sub-throttle valve, and the suction force of the sub-throttle valve towards the engine is automatically reduced. Furthermore, a friction reducing member is installed on the sliding surface between the main throttle valve and the carburetor body. Since I placed
The pressing force of the sliding throttle valve on the throttle valve guide cylinder can be reduced as much as possible, and the return of the sliding valve is smooth especially when the engine suddenly decelerates, which is extremely effective in terms of driveability and operability. It is something that can be played.

In addition, it is particularly effective when used in multiple carburetors, as it can significantly reduce the force required to return to the fully closed position compared to conventional ones.

[Brief explanation of the drawing]

The figures show an embodiment of a sliding throttle valve type carburetor according to the present invention, in which Fig. 1 is a longitudinal cross-sectional view, and Fig.
3 is a perspective view of the sliding throttle valve, and FIG. 4 is a diagram showing the relationship between the throttle valve operating load and suction negative pressure. 1... Carburetor body, 3... Throttle valve guide cylinder, 3A
...Upstream groove part, 3B...Downstream groove part, 9...Sliding throttle valve, 10...Main throttle valve, 10A...Main throttle valve guide part, 10B...Circular recess, 10C...Downstream end face , 11... Sub-throttle valve, 11A... Insertion protrusion, 11B... Sub-throttle valve guide part, 11C...
Negative pressure introduction hole, 12...pressure receiving chamber.

Claims (1)

[Scope of Claims] 1. A sliding throttle in which a throttle valve guide cylinder 3 is provided in series with an intake path 2 passing through a carburetor body 1, and a sliding throttle valve is movably disposed within the throttle valve guide cylinder. In the valve type carburetor, the sliding throttle valve 9 is composed of a main throttle valve 10 and a sub-throttle valve 11, and the main throttle valve 10 has a flat plate that can open and close the intake passage 2 on one side of the upstream side of the intake passage. A main throttle valve guide part 10A having a shape is provided, and a circular concave part 10B is formed from one side toward the other side on the downstream side of the intake passage. A circular insertion protrusion 11A is formed to be inserted into the circular recess 10B of the throttle valve 10, and a flat sub-throttle valve guide capable of opening and closing the intake passage 2 is provided on the other side of the insertion protrusion 11A on the downstream side of the intake passage. Part 11
By forming the insertion projection 11A of the sub-throttle valve 11 into the circular recess 10B of the main throttle valve 10, the pressure receiving chamber 12 is formed by the circular recess 10B and the insertion projection 11A.
At the same time, the sliding throttle valve 9 is integrally formed, and this pressure receiving chamber 12 is connected to the intake passage 2 on the engine side from the sliding throttle valve 9 through a negative pressure introduction hole 11C formed in the sub-throttle valve 11. Furthermore, the flat main throttle valve guide part 11A of the main throttle valve 10 is connected to the upstream groove part 3A of the throttle valve guide cylinder 3, and the flat plate-shaped sub throttle valve guide part 11B of the sub throttle valve 11 is connected to the throttle valve guide cylinder. A sliding throttle valve type carburetor is slidably disposed in a downstream groove section 3B, which is downstream of an upstream groove section 3A, within the interior of the interior of the valve. 2. When the sliding throttle valve 9 is at a low opening, the effective pressure receiving area of the flat plate-shaped sub-throttle valve guide portion 11B, which opens into the intake passage 2 on the engine side of the sub-throttle valve 11, is inserted to open into the pressure-receiving chamber 12. Friction is larger than the effective pressure receiving area of the protrusion 11A and is provided on the sliding surface between the flat main throttle valve guide portion 10A of the main throttle valve 10 and the upstream groove portion 3A of the carburetor body 1 to reduce the sliding friction force. A sliding throttle valve type carburetor according to claim 1, wherein a reducing member R is arranged. 3. The sliding throttle valve type carburetor according to claim 2, wherein the friction reducing member is a roller rotatably supported by the flat main throttle valve guide portion 10A of the main throttle valve 10. 4. The sliding throttle valve type carburetor according to claim 2, wherein the friction reducing member is a bearing pivotally supported by the flat main throttle valve guide portion 10A of the main throttle valve 10.