JPH0535267B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a carburetor that controls the amount and concentration of air-fuel mixture supplied to an engine, and particularly relates to a throttle valve guide tube 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 arranged and the sliding throttle valve is mechanically controlled to open and close.

[Prior Art] Conventionally, a generally used sliding throttle valve type carburetor is provided with a throttle valve guide tube that is connected to an intake passage that passes through the carburetor body and opens upward, and the sliding throttle valve A sliding throttle valve is movably slid in the valve guide cylinder, and the driver pulls the accelerator wire to open the sliding throttle valve, while when the valve is closed, the driver pulls the accelerator. It is common to close the sliding throttle valve by the spring force of the throttle valve return spring by loosening the traction on the wire. Further, the structure of this sliding throttle valve is generally cylindrical or rectangular in shape.

In the case of a cylindrical type, the curved surface of the outer side of the cylinder is slidably guided by the throttle valve guide cylinder, and in the case of a short type, the flat plate surface of the rectangle is guided by the groove of the throttle valve guide cylinder. It is slidably guided.

[Problems to be Solved by the Invention] In such a conventional sliding throttle valve type carburetor, when the engine is suddenly decelerated from a high-speed operating state, the sliding throttle valve loosens the accelerator wire. As a result, the throttle valve tries to move in the closing direction by the spring force of the return spring. On the other hand, in such a rapid deceleration operating state, the engine still maintains a high rotational speed due to inertia.

Therefore, the sliding throttle valve is in the high opening state,
When attempting to return to the low opening range, an extremely large intake passage negative pressure acts on the end face of the sliding throttle valve on the engine side, and the sliding throttle valve acts on the end face of the sliding throttle valve on the engine side. If pressed too hard, the sliding throttle valve may not return smoothly. For this reason, it is considered to strengthen the spring force of the throttle valve return spring to return the sliding throttle valve to the closing direction to increase the return force, but this will increase the opening operation force of the accelerator wire and improve operability. It is also unfavorable from the point of view of continuous operation for a long time. This phenomenon occurs in multiple sliding throttle valve type carburetors that use multiple single carburetors.
In addition, this problem becomes more noticeable when the sliding throttle valve has a rectangular shape and the contact with the sliding throttle valve guide cylinder is flat, and the intake passage diameter is large.

[Means for Solving the Problems] The sliding throttle valve type carburetor according to the present invention has been developed in view of the above problems, and its purpose is to solve the problems of the sliding throttle valve during rapid deceleration of an engine. The purpose is to improve the return characteristics in the closing direction, and in order to achieve the above objective, a throttle valve guide cylinder is provided in conjunction with the intake passage passing through the carburetor body, and the throttle valve guide cylinder slides into the throttle valve guide cylinder. In a sliding throttle valve type carburetor provided with a throttle valve, the sliding throttle valve is formed by a main throttle valve and a sub-throttle valve, and the main throttle valve is provided with a plate that is located on the air cleaner side and can open and close the intake passage. a ventilary forming part that extends from the guide part toward the engine side and is located within the intake passage and forms a ventilary with the bottom of the intake passage; and a pressure receiving chamber bored in the end surface of the ventilary forming part on the engine side. The sub-throttle valve is configured by a plate-shaped guide part that is located on the engine side and can open and close the intake passage, and a plate-shaped guide part that extends from the guide part toward the air cleaner side and forms a pressure receiving chamber of the main throttle valve. It consists of a pressure receiving chamber forming protrusion inserted into the recess, and a negative pressure introduction hole bored from the engine side end face of the guide part to the air cleaner side end face of the pressure receiving chamber forming protrusion. By inserting the pressure receiving chamber forming protrusion of the auxiliary throttle valve into the pressure receiving chamber forming recess of the throttle valve, a negative pressure introduction path is inserted between the main throttle valve and the auxiliary throttle valve into the intake passage on the engine side. A communicating pressure receiving chamber is formed, and the main throttle valve and the sub-throttle valve are integrally connected in the opening/closing direction of the intake passage, and the guide part provided on the sliding throttle valve and the guide part provided on the sub-throttle valve are connected together. It is slidably arranged in the air cleaner side guide groove and the engine side guide groove of the throttle valve guide tube.

[Function] When the sliding throttle valve is rapidly biased in the closing direction and becomes a low opening state during sudden engine deceleration, an extremely large intake tract negative occurs in the intake tract on the engine side of the sliding throttle valve. Pressure acts on the engine-side end surface of the guide portion of the sub-throttle valve to draw the sub-throttle valve toward the engine.

On the other hand, the large negative pressure in the intake tract on the engine side of the sliding throttle valve is introduced into the pressure receiving chamber composed of the main throttle valve and the sub-throttle valve through the negative pressure introduction hole. It joins the air cleaner side end surface of the pressure receiving chamber forming protrusion of the sub-throttle valve facing the sub-throttle valve and draws the sub-throttle valve toward the air cleaner side. As a result, the suction force exerted on the sub-throttle valve on the engine side is reduced, thereby improving the dynamic characteristics of the sliding throttle valve.

[Example] Hereinafter, an example of the sliding throttle valve type carburetor according to the present invention will be described with reference to the drawings.

Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes, and a sliding throttle valve guide cylinder 3 opens upward from the middle part of the intake passage 2. In this embodiment, the sliding throttle valve, which will be described later, is short and the flat guide portions at both ends of the sliding throttle valve are slidably guided. An engine side guide groove 3A and an air cleaner side guide groove 3B are formed in the direction. In the following description, the engine side refers to the right side in the figure, and the air cleaner side refers to the left side in the figure, and air flows in the intake passage 2 from left to right.

A float chamber main body 4 is disposed in the lower part of the carburetor main body 1, and a float chamber 5 is formed by the float chamber main body 4 in the lower concave portion of the vaporizer main body 1. 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, and a mixing nozzle 7 and a main jet 8 are connected to the needle jet 6, and the mixing nozzle 7 and the main jet 8 are immersed below the constant liquid level in the float chamber 5. Ru.

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 formed by a main throttle valve 10 and a sub-throttle valve 11. The main throttle valve 10 has a flat guide portion 10A that can open and close the intake passage 2 formed on one side (on the left side in the figure) facing an air cleaner (not shown). A ventilary forming portion 10B is formed toward the other side (the right side in the figure).
The vent lily forming portion 10B is located within the intake passage 2 and forms a vent lily V together with the bottom of the intake passage 2.

The aforementioned needle jet 6 opens into this ventilee V. A circular pressure receiving chamber forming recess 10C is formed on the other side (right side in the figure) facing the engine side of the ventilee forming part 10B, and an operating groove 10D is formed in the upper part. Furthermore, a jet needle 12 to be inserted into the needle jet 6 is attached to the ventilee forming portion 10B.

The sub-throttle valve 11 has a flat guide portion 11A that opens and closes the intake passage 2 formed on the other side facing the engine side (right side in the figure).
Pressure receiving chamber forming recess 10 of main throttle valve 10 toward one side (left side in the figure) on the air cleaner side from A
A circular pressure receiving chamber forming projection 11B is formed to be inserted into C, and a negative pressure introducing hole 11C is formed from the engine side end surface 11D of the guide section 11A toward the air cleaner side end surface 11E of the pressure receiving chamber forming projection 11B. is drilled.

In order to form the sliding throttle valve 9, the sub-throttle valve 1 is
The first pressure receiving chamber forming protrusion 11B is inserted into the pressure receiving chamber forming recess 10C of the main throttle valve 10. According to this, a pressure receiving chamber 13 is formed on the back surface of the guide portion 11A of the sub throttle valve 11 by the pressure receiving chamber forming recess 10C and the pressure receiving chamber forming protrusion 11B, and this pressure receiving chamber 13 has a negative pressure introduction hole 11C. It opens to the engine-side end surface 11D of the guide portion 11A of the sub-throttle valve 11 through the guide portion 11A.

The main throttle valve 10 and the sub-throttle valve 11 are constructed by inserting the pressure-receiving chamber-forming protrusion 11B of the sub-throttle valve 11 into the pressure-receiving chamber-forming recess 10C of the main throttle valve 10. It can move following the opening/closing movement of 2.

Incidentally, in order to improve the pressure holding characteristics of the pressure receiving chamber 13, a sealing member 14 may be arranged between the insertion portions.

Reference numeral 15 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, reference numeral 16 denotes a throttle valve return spring that applies a biasing force in the closing direction to the sliding throttle valve 9 via the throttle valve lever 15.

Next, the assembly of the sliding throttle valve 9 will be described.

First, insert the pressure receiving chamber forming protrusion 11B of the sub throttle valve 11 into the pressure receiving chamber forming recess 10C of the main throttle valve 10,
A sliding throttle valve 9 is formed.

According to this, a flat guide portion 10A is formed on one side of the sliding throttle valve 9 on the air cleaner side,
A flat guide portion 11A is formed on the other side of the engine side, and the pressure receiving chamber forming recess 10C and the pressure receiving chamber forming protrusion 11B are formed on the back portion (air cleaner side) of the guide portion 11A of the sub throttle valve 11. A pressure receiving chamber 13 is formed.

The sliding throttle valve 9 configured as described above is arranged in the sliding throttle valve guide tube 3 of the carburetor main body 1. At this time, the flat guide portion 10A of the main throttle valve 10 is connected to the air cleaner. The flat guide portion 11A of the sub throttle valve 11 is slidably arranged within the side guide groove 3B, and the flat guide portion 11A of the sub throttle valve 11 is slidably arranged within the engine side guide groove 3A.

The main throttle valve 10 is formed by the guide portion 10A of the main throttle valve 10, which is one side of the sliding throttle valve 9 on the air cleaner side, and is disposed facing the air intake passage 2 on the air cleaner side. The other side surface is formed by the guide portion 11A of the sub-throttle valve 11 and is disposed opposite to the intake passage 2 on the engine side.

On the other hand, a connecting means R such as a roller attached to the throttle valve lever 15 is arranged in the operating groove 10D of the main throttle valve 10 of the sliding throttle valve 9 disposed in the sliding throttle valve guide tube 3. Rotation of the throttle valve lever 15 is transmitted to the sliding throttle valve 9.

When the throttle valve lever 15 is rotated by the driver, the rotation of the throttle valve lever 15 is transmitted to the operation groove 10D of the main throttle valve 10 via the connecting means R, and the main throttle valve 10 is rotated. The movement of the main throttle valve 10 is caused by the insertion of the sub-throttle valve 11 into the pressure receiving chamber forming protrusion 11B into the pressure receiving forming recess 10C of the main throttle valve 10. and is synchronously transmitted to the sub-throttle valve 11, thereby transmitting the signal to the sub-throttle valve 1 of the main throttle valve 10.
A sliding throttle valve 9 formed by 1 and 1 can control the opening and closing of the intake passage in synchronization with the rotation of the operating lever 15.

Next, to explain its operation, during constant opening operation where the sliding throttle valve 9 is held at a constant opening degree, during acceleration operation where the sliding throttle valve 9 is opened, and when the sliding throttle valve 9 is gradually closed. During normal slow deceleration operation, the intake path 2B on the engine side is connected to the sliding throttle valve 9.
No particularly large intake tract negative pressure is generated.
Therefore, the sliding throttle valve 9 is attracted to the engine side, the guide portion 11A is attracted to the engine side of the throttle valve guide tube 3, and the guide portion 11A is pressed against the engine side guide groove 3A of the throttle valve guide tube 3. Therefore, the driver's opening/closing operations on the main throttle valve 10 are immediately transmitted and can be performed smoothly without any resistance.

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 the opening to the intake path 2 is relatively small, the engine-side end surface 11D of the guide portion 11A of the sub-throttle valve 11 constituting the sliding throttle valve 9 is connected to the engine-side intake path 2.
Since the sliding throttle valve 9 is not subjected to a large amount of negative pressure B, the sliding throttle valve 9 is smoothly closed to the intermediate opening range.

When the sliding throttle valve 9 returns from the intermediate opening range to the lower opening range and attempts to block the intake passage 2, the engine continues to rotate at high speed due to inertia, and as a result, the inside of the intake passage 2 is A high intake tract negative pressure occurs.

In the conventional device, in such a state, a large suction force acts on the side surface of the sliding throttle valve 9 on the engine side, causing the sliding throttle valve 9 to return smoothly, but the present invention According to the sliding throttle valve type carburetor, high intake passage negative pressure generated in the intake passage 2B on the engine side acts on the engine side end surface 11D of the guide portion 11 of the sub throttle valve 11, causing the sub throttle valve 11 to A suction force is exerted toward the engine side in the right direction in the figure, but this high intake passage negative pressure in the intake passage 2B on the engine side is also introduced into the pressure receiving chamber 13 via the negative pressure introduction hole 11C.

According to this, since the back part of the sub-throttle valve 11 (the end face 11E on the air cleaner side of the pressure-receiving chamber forming projection 11B) faces the pressure receiving chamber 13 and is open, the back part of the sub-throttle valve 11 causes suction in the left direction in the figure. Power is generated.

Therefore, the auxiliary throttle valve 11, which receives high intake tract negative pressure on the engine side, has a leftward suction force acting on its back and a rightward suction force acting on the guide portion 11A of the auxiliary throttle valve 11 that opens into the engine side intake tract 2B. It will be biased with a pressing force equal to the difference between the suction force and the suction force.

Here, the effective pressure-receiving area of the guide portion 11A for the sub-throttle valve 11 and the engine-side intake passage 2B is defined as the effective pressure-receiving area of the pressure-receiving chamber 13.
The back of the sub-throttle valve 11 facing inward (pressure receiving chamber forming protrusion 1
By making the effective pressure receiving area larger than the effective pressure receiving area applied to the air cleaner side end surface 11E of 1B, a suction force toward the engine equal to the difference will be applied to the guide portion 11A of the sub throttle valve 11.

Therefore, in the sliding throttle valve 9, the guide portion 11A of the sub-throttle valve 11 is only biased and held by the engine-side guide groove 3A of the throttle valve guide cylinder 3 with a slight pressing force, so that during such rapid deceleration operation. Sliding throttle valve 9
This allows the sliding throttle valve 9 to return to a low opening degree smoothly and reliably without being attracted to the throttle valve guide cylinder 3 with strong force.

In addition, in the case where it is not necessary to suppress the amount of leakage from the sliding throttle valve 9 to the engine to a very small extent when the sliding throttle valve 9 is opened at a low opening, the guide portion 11A of the sub-throttle valve 11 may The effective pressure receiving area for the side intake passage 2B is made equal to or smaller than the effective pressure receiving area applied to the back part of the sub-throttle valve 11 facing the pressure receiving chamber 13 (the end surface 11E on the air cleaner side of the pressure receiving chamber forming projection 11B). Possibly the sub-throttle valve 11
The guide portion 11A can be actively floated above the engine side guide groove 3A of the throttle valve guide cylinder, and the return force can be further reduced.

[Effects of the Invention] As described above, according to the sliding throttle valve type carburetor of the present invention, the pressing force of the sliding throttle valve against the throttle valve chamber cylinder can be reduced as much as possible, especially when the sliding valve is in sudden deceleration operation of the engine. It has a smooth return property, and can have extremely large effects in terms of driveability, operability, and safety.

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, and FIG. 1 is a vertical sectional view, and FIG.
FIG. 3 is a perspective view of the sliding throttle valve. 1... Carburetor body, 2... Intake path, 2A... Intake path on the air cleaner side, 2B... Intake path on the engine side, 3... Throttle valve guide tube, 3A... Engine side guide groove, 3B... ...Air cleaner side guide groove, 9...Sliding throttle valve, 10...Main throttle valve, 10A...Guide part, 10B...Venture forming part, 10C...
Pressure receiving chamber forming recess, 11... Sub-throttle valve, 11A...
Guide portion, 11B...Pressure chamber forming protrusion, 11C...
...Negative pressure introduction hole, 11D... Engine side end surface of guide portion 11A, 13... Pressure receiving chamber.

Claims (1)

[Scope of Claims] 1. In a sliding throttle valve type vaporizer in which a throttle valve guide tube is provided in series with an intake passage passing through the carburetor body, and a sliding throttle valve is disposed within the throttle valve guide tube: The dynamic throttle valve 9 is formed by a main throttle valve 10 and a sub-throttle valve 11. It extends toward the engine side and is located inside the intake passage 2.
A bench lily forming part 10B forming a vent lily V together with the bottom of the vent lily forming part 10B.
Pressure receiving chamber forming recess 1 bored in the engine side end face of B
0C, and the sub-throttle valve 11 is located on the engine side and has a plate-shaped guide portion 1 that can open and close the intake passage 2.
1A, and a pressure receiving chamber forming protrusion 11 that extends from the guide portion 11A toward the air cleaner side and is inserted into the pressure receiving chamber forming recess 10C of the main throttle valve 10.
B and the air cleaner side end surface 1 of the pressure receiving chamber forming projection 11B from the engine side end surface 11D of the guide portion 11A.
The pressure receiving chamber forming recess 10 of the main throttle valve 10
By inserting the pressure receiving chamber forming projection 11B of the sub-throttle valve 11 into C, the main throttle valve 10 and the sub-throttle valve 1
A pressure receiving chamber 13 is formed between the main throttle valve 10 and the sub-throttle valve 11 which are connected to the intake passage 2B on the engine side via the negative pressure introduction passage 11C, and the main throttle valve 10 and the sub-throttle valve 11 are integrated in the opening and closing direction of the intake passage 2. The guide portion 10A provided on the main throttle valve 10 of the sliding throttle valve 9 and the guide portion 11A provided on the sub throttle valve 11 are connected to the air cleaner side guide groove 3B of the throttle valve guide tube 3 and the engine side guide groove. A sliding throttle valve type carburetor that is slidably arranged on 3A. 2. In a sliding throttle valve type carburetor in which a throttle valve guide cylinder is provided adjacent to the intake passage passing through the carburetor body and a sliding throttle valve is disposed within the throttle valve guide cylinder, the sliding throttle valve 9 is the main A plate-shaped guide portion 10A is formed of a throttle valve 10 and a sub-throttle valve 11, and is located on the air cleaner side and can open and close the intake passage 2.
and a vent turret forming part 10B which extends from the guide part 10A toward the engine side and is located inside the intake passage 2 and forms a vent lily V together with the bottom of the intake passage 2; a plate-shaped guide part 11A that can open and close the intake passage 2 while placing the sub-throttle valve 11 on the engine side; Pressure receiving chamber forming recess 10 of main throttle valve 10
The pressure receiving chamber forming projection 11B inserted into the pressure receiving chamber forming projection 11B and the negative pressure introduction hole 11C bored from the engine side end surface 11D of the guide section 11A toward the air cleaner side end surface 11E of the pressure receiving chamber forming projection 11B. By inserting the pressure receiving chamber forming protrusion 11B of the sub throttle valve 11 into the pressure receiving chamber forming recess 10C of the main throttle valve 10, a negative pressure is created between the main throttle valve 10 and the sub throttle valve 11. Air intake path 2B on the engine side via the pressure introduction hole 11C
A guide provided on the main throttle valve 10 of the sliding throttle valve 9 forms a pressure receiving chamber 13 connected to the sliding throttle valve 9 and integrally connects the main throttle valve 10 and the sub-throttle valve 11 in the opening/closing direction of the intake passage 2. The guide portion 11A provided in the section 10A and the sub-throttle valve 11 is connected to the air cleaner side guide groove 3B of the throttle valve guide tube 3 and the engine side guide groove 3.
A and a sliding throttle valve 9.
When the opening degree is low, the guide portion 1 of the sub-throttle valve 11
Engine side intake path 2B of engine side end face 11D of 1A
The air cleaner side end surface 1 of the pressure chamber forming protrusion 11B facing into the pressure chamber 13 has an effective pressure receiving area opened to
A sliding throttle valve type carburetor with an effective pressure receiving area larger than that of 1E.