JPH0511213B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an air intake passage that has an opening area approximately at the middle of the intake passage passing through the carburetor body in accordance with the intake passage negative pressure generated within the intake passage. This invention relates to a constant vacuum carburetor equipped with a variably controlled negative pressure operated valve and a sliding throttle valve disposed in the intake path downstream of the negative pressure operated valve (intake path on the engine side).

[Conventional technology]

Generally, in a constant vacuum type vaporizer, a partition made of a diaphragm or the like is placed above a negative pressure operated valve, and an atmospheric chamber is formed by this partition and a recess in the vaporizer body. A pressure receiving chamber is formed by the top cover and the upper suction force against the negative pressure operated valve due to the negative pressure in the intake passage introduced into the pressure receiving chamber, and the downward suction force against the negative pressure operated valve due to the spring compressed in the pressure receiving chamber. The position of the negative pressure operated valve in the intake passage is controlled by the force relationship with the pressing force in the direction, thereby obtaining the optimum ventilate opening degree for engine operation. A sliding throttle valve that opens and closes the intake duct area is arranged in the side intake duct. Hereinafter, the terms "upstream side" and "downstream side" are based on the airflow flowing through the intake tract. For example, in FIG. 1, the air flows from left to right in the intake tract, with the left side being upstream and the right side being downstream. The air cleaner side corresponds to the upstream side, and the engine side corresponds to the downstream side.

This sliding throttle valve is a sliding throttle valve that is movably arranged approximately perpendicular to the intake passage in a throttle valve guide cylinder that is connected to the intake passage that passes through the carburetor body and opens upward. The driver pulls the accelerator wire upwards to open the sliding throttle valve to open the intake passage, while when the throttle valve is blocked, the driver loosens the accelerator wire to release the throttle valve return spring. Generally, the sliding throttle valve is pushed down by the spring force of the valve 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, a rectangular flat plate portion is guided by a groove portion of a flat throttle valve guide cylinder.

[Problem to be solved by the invention]

In such a constant vacuum carburetor, when the engine is suddenly decelerated from a high-speed operating state, the sliding throttle valve attempts to move in the closing direction by loosening the accelerator wire; In this state, the engine still maintains high rotational speed due to inertia. Therefore, an extremely large intake passage negative pressure acts on the downstream (engine side) end face of the sliding throttle valve. 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 multiple constant vacuum vaporizers that use multiple single vaporizers.
In addition, this phenomenon becomes more noticeable when the sliding throttle valve has a rectangular shape and the contact with the throttle valve guide cylinder is planar, and the intake passage diameter is large. If the sliding throttle valve does not return smoothly in the closing direction, the opening degree of the negative pressure operated valve becomes inappropriate and is pulled up unnecessarily, making it difficult to maintain an appropriate mixture concentration and reducing the amount of fuel. This impairs economic efficiency.

[Means to solve the problem]

The constant vacuum carburetor of the present invention has been developed in view of the above-mentioned problems, and its purpose is to improve the obstruction of the sliding throttle valve when the engine suddenly decelerates. In order to achieve the above purpose, a negative pressure operating valve guide cylinder 3 is provided above the middle part of the intake passage 2 that passes through the carburetor body 1, and the negative pressure operating valve is maintained at an appropriate opening degree. A negative pressure operated valve 9 that controls the opening area of the intake passage 2 according to the negative pressure within the intake passage 2 is disposed inside the guide cylinder 3, and the intake passage 2 on the engine side from the negative pressure operated valve 9 is slidably moved. In a constant vacuum carburetor whose opening and closing are controlled by a throttle valve, the sliding throttle valve 17 is connected to the main throttle valve 18 and the sub-throttle valve 1.
9, the main throttle valve 18 is provided with a flat plate-shaped main throttle valve guide portion 18A that can open and close the intake passage 2 on one side of the upstream side of the intake passage, and a main throttle valve guide part 18A of the main throttle valve 18 that can open and close the intake passage 2 is provided on one side of the upstream side of the intake passage. A circular recess 18B is formed toward the other side, and the sub throttle valve 19 has a circular insertion protrusion 19A inserted into the circular recess 18B of the main throttle valve 18 on one side of the upstream side of the intake path. At the same time, on the other side of the intake path downstream of the insertion protrusion 19A, there is a flat sub-throttle valve guide portion 19 that can open and close the intake path 2.
By forming the insertion projection 19A of the sub-throttle valve 19 into the circular recess 18B of the main throttle valve 18, the pressure receiving chamber 21 is formed by the circular recess 18B and the insertion projection 19A.
and a sliding throttle valve 17 is formed, and this pressure receiving chamber 21 is connected to the intake passage 2 on the engine side from the sliding throttle valve 17 via a negative pressure introduction hole 19C formed in the sub-throttle valve 19. Furthermore, the flat main throttle valve guide part 18A of the main throttle valve 18 is provided in the upstream groove part 16 in the carburetor main body 1 on the downstream side of the negative pressure operation valve guide cylinder 3.
In A, a flat plate-shaped sub-throttle valve guide portion 19B of the sub-throttle valve 19 is slidably disposed in a downstream groove portion 16B provided in the carburetor main body 1 on the engine side of the carburetor main body 1.

[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. As a result, the dynamic characteristics of the sliding throttle valve and the dynamic characteristics of the negative pressure operated valve can be improved.

〔Example〕

Hereinafter, one embodiment of the constant vacuum type vaporizer 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 negative pressure operating valve guide cylinder 3 is connected above the middle part of the intake passage 2, and further, from the upper opening of the negative pressure operating valve guide cylinder 3. This is a carburetor main body with an atmospheric chamber recess 4 formed on the side. A float chamber 6 is formed by the lower concave portion of the carburetor body 1 and the float body 5, and a constant liquid is kept in the float chamber 6 by a valve seat, a float valve (not shown), and a float. A surface is formed. Intake tract 2
A needle jet 7 is opened in the needle jet 7, and a mixing pipe is connected to the needle jet 7, in which fuel controlled by a main fuel jet (not shown) and air controlled by a main air jet (not shown) are mixed. 8 to provide a mixture. On the other hand, a negative pressure operated valve 9 for controlling the opening area of the intake passage 2 is slidably disposed inside the negative pressure operated valve guide cylinder 3, and a needle jet 7 is inserted into the bottom of the valve 9 to control the opening area of the intake passage 2. A jet needle 10 that controls the amount of air-fuel mixture to be sucked out in synchronization with the movement of the negative pressure operating valve 9 is installed upright, and a compartment body 11 made of a diaphragm such as epichlorohydrin rubber is disposed above the jet needle 10. The end of the body 11 is sandwiched between the carburetor body 1 and the top cover 12, and an atmospheric chamber 13 is formed between the compartment body 11 and the atmospheric chamber recess 4 of the carburetor body 1, while the compartment body 11 and the top cover 12 A pressure receiving chamber 14 is formed by this. Incidentally, reference numeral 15 denotes a spring compressed within the pressure receiving chamber 14 between the top cover 12 and the negative pressure operating valve 9.

Reference numeral 16 denotes a throttle valve guide cylinder that opens upward from the intake passage 2 on the downstream side of the negative pressure operated valve 9. In this embodiment, the sliding throttle valve is rectangular, and flat guide portions are provided at both ends of the sliding throttle valve. (described later), in FIG. 1, an upstream groove portion 16A of the throttle valve guide cylinder 16 and a downstream groove portion 16B located downstream (to the right in the figure) from the upstream groove portion 16A are formed. The upstream groove portion 16A and the downstream groove portion 16B are perforated across the intake passage 2 in the vertical direction in FIG.

A sliding throttle valve 17 is movably disposed within the throttle valve guide cylinder 16 . This sliding throttle valve 17 is
This will be explained in detail with reference to FIGS. The sliding throttle valve 17 is formed by a main throttle valve 18 and a sub-throttle valve 19. The main throttle valve 18 has a flat main throttle valve guide portion 18A that can open and close the intake passage 2 on one side on the upstream side of the intake passage, and has a pressure receiving chamber (to be described later) on the other side on the downstream side of the intake passage. In order to form a circular recess 18B, a circular recess 18B is bored. This flat main throttle valve guide portion 18A is connected to the carburetor main body 1 as described above.
is arranged in the upstream groove portion 16A of the main throttle valve guide portion 18A, particularly the downstream end surface 1 of the flat main throttle valve guide portion 18A.
The sliding surface between 8C and the upstream groove portion 16A slides through the friction reducing member 20. This friction reducing member 2
0 may be anything that reduces the frictional force on the sliding surface, specifically, the main throttle valve guide 1 of the main throttle valve 18.
Uses a rotatably supported roller or bearing on 8A.

On the other hand, a circular insertion protrusion 19A that is inserted into the circular recess 18B of the main throttle valve 18 is formed on one side of the sub-throttle valve 19 on the upstream side of the intake passage, and on the other side of the upstream side of the intake passage. A flat sub-throttle valve guide portion 19B that opens and closes is formed. This sub-throttle valve guide portion 19B is arranged within the downstream groove portion 16B of the carburetor main body 1.

Then, by inserting the insertion protrusion 19A of the sub-throttle valve 19 into the circular recess 18B of the main throttle valve 18, the circular recess 18B and the insertion protrusion 19A form a flat plate-shaped sub-throttle valve guide portion of the sub-throttle valve 19. A pressure-receiving chamber 21 is formed at the back of 19B. In order to improve the pressure holding characteristics of the pressure receiving chamber 21, a sealing member 22 may be disposed at the insertion portion thereof. A negative pressure introduction hole 19C formed in the sub-throttle valve 19 is provided in the pressure-receiving chamber 21 to introduce negative pressure in the intake passage downstream of the sub-throttle valve 19 (on the engine side).

The accelerator wire 23 is operated by the driver, and its end is mechanically connected to the main throttle valve 18 of the sliding throttle valve 17. Further, 24 is a throttle valve return spring that applies a biasing force to the sliding throttle valve 17 in the closing direction.

Next, to describe how to assemble the sliding throttle valve 17, first insert the insertion protrusion 19A of the sub-throttle valve 19 into the circular recess 18B of the main throttle valve 18, and then
form 7. According to this, a flat main throttle valve guide section 18A is formed on one side surface on the upstream side, and a flat sub throttle valve guide section 19B is formed on the other side surface on the downstream side. The circular recess 18B is formed on the back of the sub-throttle valve guide portion 19B.
A pressure receiving chamber 21 is formed by the insertion protrusion 19A. When the sliding throttle valve 17 is at a low opening, the effective pressure receiving area of the sub throttle valve guide portion 19B of the sub throttle valve 19 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 of the insertion protrusion 19A of the sub-throttle valve 19 of No. 1.

The sliding throttle valve 17 configured as described above is disposed within the throttle valve guide tube 16 of the carburetor main body 1. At this time, in particular, the flat main throttle valve guide portion 18A of the main throttle valve 18 is Upstream groove section 16A
The flat plate-shaped sub-throttle valve guide portion 19B of the sub-throttle valve 19 must be placed within the throttle valve guide cylinder 16 within the downstream groove portion 16B.

In this state, the main throttle valve 18 and the sub-throttle valve 19 open and close the intake passage 2 of the sliding throttle valve 17 because the insertion protrusion 19A of the sub-throttle valve 19 is inserted into the circular recess 18B of the main throttle valve 18. During operation, the main throttle valve 18 and the sub-throttle valve 19 can operate synchronously and integrally.

Next, to explain its function, during engine operation with the sliding throttle valve 17 at a constant opening, or during acceleration and normal deceleration operation in which the sliding throttle valve 17 is gradually closed, the downstream side of the sliding throttle valve 17 is No particularly large intake tract negative pressure is generated in the side intake tract 2. Therefore, the sliding throttle valve 17 is not sucked downstream and the sub-throttle valve guide portion 19B is not strongly sucked and pressed against the downstream side groove portion 16B of the throttle valve guide tube 16, so that the driver's contact with the main throttle valve 17 is prevented. Opening/closing operations are immediately transmitted to the sub-throttle valve 19 and can be performed extremely smoothly. Therefore, the negative pressure operated valve 9 can also maintain an appropriate ventilate opening degree suitable for the negative pressure in the intake passage.

Next, when we look at the sudden deceleration operation in which the sliding throttle valve 17 is suddenly closed from the high-speed operating state of the engine with the sliding throttle valve 17 opened to a high opening degree, the sliding throttle valve 17
up to a certain intermediate opening range, the intake passage 2 of the sliding throttle valve 17
Since there are relatively few openings to the air, the effect of negative pressure in the intake tract is small and can be easily restored. However, when the sliding throttle valve 17 returns to the low opening range and attempts to block the intake passage 2, the engine still rotates at high speed due to inertia, resulting in a high intake passage negative pressure inside the intake passage 2. is occurring. If it is a conventional one,
In such a state, the suction force acting on the downstream side of the sliding throttle valve 17 sometimes lacks smooth return, but according to the constant vacuum type carburetor of the present invention, the suction force on the downstream side of the sliding throttle valve 17 A suction force in the right direction acts on the opening to the intake passage 2 on the engine side, that is, the sub-throttle valve guide part 19B, in the drawing towards the downstream side (engine side), but this intake passage negative pressure is transferred to the negative pressure introduction hole 19C. It is also introduced into the pressure receiving chamber 21 via.

According to this, since the back of the sub-throttle valve 19, that is, the insertion protrusion 19A is open in the pressure-receiving chamber 21, a suction force is generated in the back of the sub-throttle valve 19 in the left direction in the figure. Therefore, the sub-throttle valve 19, which receives high negative pressure in the intake passage on the downstream side (engine side), has a suction force in the left direction generated at its back and the sub-throttle valve guide portion of the sub-throttle valve 19 that opens into the intake passage on the engine side. It will be biased by a pressing force equal to the difference between the rightward suction force generated at 19B and the rightward suction force.

In this embodiment, as described above, the sub throttle valve 19
The sub-throttle valve guide part 1 for the intake passage 2 on the downstream side of
The effective pressure receiving area of 9B is the sub-throttle valve 19 of the pressure receiving chamber 21.
Since the area is larger than the effective pressure receiving area applied to the back of the sub-throttle valve 19, a suction force to the downstream side (engine side) equal to the difference is applied to the sub-throttle valve guide portion 19B of the sub-throttle valve 19.

Therefore, in the sliding throttle valve 17, the sub-throttle valve guide portion 19B of the sub-throttle valve 19 is only biased and held in the downstream groove portion 16B of the sliding throttle valve guide cylinder 16 with a slight pressing force. The sliding throttle valve 19 is not attracted to the sliding throttle valve guide cylinder 16 during sudden deceleration operation.

On the other hand, in the case of the main throttle valve 18, especially the pressure receiving chamber 2
1 is sucked toward the engine side (right side in the figure) by the intake passage negative pressure introduced into the main throttle valve 1. It tends to increase with respect to the sliding friction force. However, in the present invention, friction reducing members 20 such as rollers and bearings are provided on such sliding surfaces.
, the return force of the main throttle valve 18 is also reduced during such deceleration operation. If the sliding throttle valve 17 can be smoothly returned to the closing direction, the negative pressure in the intake passage 2 will always be maintained at an appropriate level, and the opening degree of the negative pressure operated valve 9 will also be maintained at an appropriate level. It is possible to bring out the desired performance.

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 downstream side of the sub-throttle valve guide portion 19B of the sub-throttle valve 19 may be Side (engine side) intake path 2
The effective pressure-receiving area for the sub-throttle valve 1 of the pressure-receiving chamber 21
Make the effective pressure-receiving area applied to the back of 9 equal, or
Alternatively, by making the sub-throttle valve smaller, the sub-throttle valve can be positively floated above the throttle-valve guide cylinder, and its return force can be further reduced.

〔Effect of the invention〕

As described above, according to the constant vacuum carburetor of the present invention, the pressing force of the sliding throttle valve against the throttle valve guide cylinder can be reduced as much as possible, and especially the return performance of the sliding valve during sudden engine deceleration operation can be made smooth. This can have an extremely large effect in terms of drivability and operability.

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.

As mentioned above, since we were able to improve the ability of the sliding throttle valve to return to the closing direction, the negative pressure responsive valve is able to maintain the intake passage negative pressure that perfectly matches the engine operation into the pressure receiving chamber of the negative pressure responsive valve. This allows the opening of the negative pressure operated valve to be optimally controlled, allowing the characteristics of a constant vacuum carburetor (fuel atomization, fuel economy) to be effectively utilized.

[Brief explanation of the drawing]

The figures show an embodiment of the constant vacuum type vaporizer according to the present invention, in which Fig. 1 is a longitudinal cross-sectional view, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, and Fig. 3 is a sliding aperture. FIG. 3 is a perspective view of the valve. 1... Carburetor main body, 3... Negative pressure operation valve guide cylinder,
9... Negative pressure operated valve, 16... Throttle valve guide cylinder, 16
A...Upstream groove part, 16B...Downstream groove part, 17
...Sliding throttle valve, 18...Main throttle valve, 18A...
Main throttle valve guide part, 18B...Circular recess, 19...
...Sub-throttle valve, 19A...Sub-throttle valve insertion protrusion.

Claims (1)

[Scope of Claims] 1. A negative pressure operating valve guide cylinder 3 is provided above the middle part of the intake passage 2 that passes through the carburetor main body 1, and inside the negative pressure operating valve guide cylinder 3 there is a A constant vacuum type in which a negative pressure operated valve 9 is arranged to control the opening area of the intake passage 2 according to the negative pressure of the intake passage 2, and the opening and closing of the intake passage 2 downstream of the negative pressure operated valve 9 is controlled by a sliding throttle valve. In the carburetor, the sliding throttle valve 17 is divided into a main throttle valve 18 and a sub-throttle valve 1.
9, the main throttle valve 18 is provided with a flat plate-shaped main throttle valve guide portion 18A that can open and close the intake passage 2 on one side of the upstream side of the intake passage, and a main throttle valve guide part 18A of the main throttle valve 18 that can open and close the intake passage 2 is provided on one side of the upstream side of the intake passage. A circular recess 18B is formed toward the other side, and the sub throttle valve 19 has a circular insertion protrusion 19A inserted into the circular recess 18B of the main throttle valve 18 on one side of the upstream side of the intake path. At the same time, on the other side of the intake path downstream of the insertion protrusion 19A, there is a flat sub-throttle valve guide portion 19 that can open and close the intake path 2.
By forming the insertion projection 19A of the sub-throttle valve 19 into the circular recess 18B of the main throttle valve 18, the pressure receiving chamber 21 is formed by the circular recess 18B and the insertion projection 19A.
At the same time, the sliding throttle valve 17 is integrally formed, and this pressure receiving chamber 21 is connected to the intake passage 2 on the engine side from the sliding throttle valve 17 via a negative pressure introduction hole 19C formed in the sub-throttle valve 19. Furthermore, the flat plate-shaped main throttle valve guide part 18A of the main throttle valve 18 is connected to the upstream groove part 16A provided in the carburetor main body 1 on the downstream side of the negative pressure operation valve guide tube 3. A constant vacuum type carburetor in which a shaped sub-throttle valve guide part 19B is slidably disposed in a downstream groove part 16B provided in the carburetor main body 1 on the downstream side of the upstream groove part 16A. 2. When the sliding throttle valve 17 is at a low opening, the effective pressure receiving area of the flat plate-shaped sub-throttle valve guide portion 19B, which opens into the intake passage 2 on the engine side of the sub-throttle valve 19, is inserted to open into the pressure-receiving chamber 21. The friction is larger than the effective pressure receiving area of the protrusion 19A and is provided on the sliding surface between the flat main throttle valve guide part 18A of the main throttle valve 18 and the upstream groove part 16A of the carburetor body 1 to reduce the sliding friction force. Claim 1 in which a reducing member is arranged
Constant vacuum vaporizer as described in section. 3. The constant vacuum carburetor according to claim 2, wherein the friction reducing member is a roller rotatably supported on the flat main throttle valve guide portion 19B of the main throttle valve 19. 4. The constant vacuum carburetor according to claim 2, wherein the friction reducing member is a bearing pivotally supported by the flat main throttle valve guide portion 19B of the main throttle valve 19.