JPS6021468Y2 - Flow path control device for helical intake port - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flow path control device for a helical intake port.

A helical intake port is usually comprised of a spiral portion shaped at the intake station and an inlet passageway tangentially connected to the spiral portion and extending substantially straight.

If you try to use such a helical intake port to generate a strong swirling flow in the combustion chamber of the engine when the engine is operating at low speed and low load with a small amount of intake air, the shape of the intake port will have a large flow resistance. There is a problem in that the filling efficiency decreases when the engine is operated at high speed and under high load with a large amount of air.

In order to solve this problem, a branch passage is formed in the cylinder head that branches from the helical intake port inlet passage and communicates with the spiral end of the helical intake port spiral part, and an actuator is inserted into the branch passage. The present application provides a helical intake port flow path control device that is provided with a normally closed on-off valve that is operated and operates an actuator to open the on-off valve when the amount of engine intake air becomes larger than a predetermined amount. Already suggested by someone.

In this helical type intake port, when the engine is operated at high speed and under high load with a large amount of engine intake air, part of the intake air sent into the helical type intake port inlet passage is sent into the helical type intake port spiral part through the branch passage. The flow resistance to the intake air flow is reduced and thus a high filling efficiency can be obtained.

However, this flow path control device only shows the basic operating principle, and therefore, there are various problems in terms of assembly man-hours, ease of manufacturing, reliable operation, and manufacturing cost in order to put this flow path control device into practical use. is left behind.

The object of the present invention is to provide a helical intake port flow path control device having a structure suitable for putting into practical use the above-mentioned basic operating principle that has already been proposed by the applicant.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1 and FIG. 2, 1 is a cylinder block, 2 is a piston that reciprocates within the cylinder block 1,
3 is a cylinder head fixed on the cylinder block 1, 4 is a combustion chamber formed between the piston 2 and the cylinder head 3, 5 is an intake valve, 6 is a helical intake port formed in the cylinder head 3, 7 8 indicates an exhaust valve, and 8 indicates an exhaust port formed in the cylinder head 3.

Although not shown in the figure, an ignition plug is disposed within the combustion chamber 4.

4 to 6 schematically show the shape of the helical intake port 6 of FIG. 2.

As shown in FIG. 5, this helical intake port 6 is composed of an inlet passage section A in which the flow path axis a is slightly curved, and a spiral section B formed around the valve axis of the intake valve 5.
The inlet passage section A is tangentially connected to the spiral section B.

As shown in FIGS. 4, 5, and 8, the upper side wall surface 9a of the side wall surface 9 of the inlet passage A on the side closer to the spiral axis
is formed as an inclined surface facing downward, and the width of this inclined surface 9a becomes wider as it approaches the spiral part B, and at the connection part between the inlet passage part A and the spiral part B, as shown in FIG. The entire wall surface 9 is formed into an inclined surface 9a facing downward.

The upper half of the side wall surface 9 is smoothly connected to the peripheral wall surface of the cylindrical upper protrusion 11 formed on the upper wall surface of the intake port around the intake valve guide 10 (FIG. 2), while the lower half of the side wall surface 9 is connected to the spiral portion. It is connected to the side wall surface 12 of the spiral portion B at the spiral end portion C of the spiral portion B.

Note that the upper wall surface 13 of the spiral portion B is connected to a steeply downwardly inclined wall at the spiral end portion C.

On the other hand, as shown in FIGS. 1 to 6, a branch passage 14 having a substantially uniform cross section is formed in the cylinder head 3, branching from the inlet passage part A, and this branch passage 14 is connected to the spiral terminal part C.
connected to.

An inlet opening 15 of the branch passage 14 is formed on the side wall surface 9 in the vicinity of the inlet opening of the inlet passage section A, and an outlet opening 16 of the branch passage 14 is formed on the upper end of the side wall surface 12 at the spiral end C.

The upper end edge of this outlet opening 16 is connected flush with the upper wall surface 13 of the spiral part B, and the outlet opening 16 is arranged so as to face the swirling flow that swirls in the spiral direction along the earth wall surface 13 of the spiral part B. It is formed.

An on-off valve insertion hole 17 is formed in the cylinder head 3 and extends through the branch passage 14, and a rotary valve 18 constituting an on-off valve is inserted into each on-off valve insertion hole 17.

Referring to FIG. 10, the on-off valve insertion hole 17 consists of a cylindrical hole of uniform diameter drilled from above in the cylinder head 3, and this on-off valve insertion hole 17 extends beyond the lower wall surface of the branch passage 14. Extends to a certain extent.

Therefore, a groove 19 covered by the opening/closing valve insertion hole 17 is formed on the lower wall surface of the branch passage 14 .

Further, an internal thread 20 is screwed onto the upper end of the on-off valve insertion hole 17, and a rotary valve holder 21 is screwed onto this thread 20.

The rotary valve holder 21 has an outer peripheral flange 22 on its outer peripheral wall surface, and the outer peripheral flange 22 and the cylinder head 3
A sealing member 23 is inserted between them.

On the other hand, a through hole 24 is bored in the rotary valve holder 21, and a valve shaft 25 of the rotary valve 18 is rotatably inserted into the through hole 24.

A thin plate-shaped valve body 26 is fixed to the lower end of the valve shaft 25, and an arm 27 is fixed to the upper end of the valve shaft 25 with a bolt 29 through a washer 28.

As shown in FIG. 14, the valve body 26 has a streamlined shape with a front edge 26a and a rear edge 26b having a model cross-sectional shape, so that when the valve body 26 is in the position shown in FIG. The flow resistance caused by 26 is made as small as possible.

On the other hand, a ring groove 30 is formed on the outer circumferential wall surface of the valve shaft 25 at approximately the same position as the upper end surface of the rotary valve holder 21, and a C-shaped positioning ring as shown in FIG. 31 is fitted.

This positioning ring 31 engages with a conical surface 32 formed on the inner edge of the upper end surface of the rotary valve holder 21 to position the valve body 26 at a predetermined position.

On the other hand, the upper end of the rotary valve holder 21 has reinforcing frames 3 and 3.
The seal member 34 surrounded by the seal member 34 is fitted, and the seal portion 34a of the seal member 34 is pressed against the outer circumferential surface of the valve shaft 25 by an elastic ring 35 inserted onto the outer circumferential wall surface of the seal member 34.

The branch 14 is therefore completely isolated from the outside air by the sealing elements 23,34.

Since the seal member 34 is fixed on the rotary valve holder 21, when the rotary valve 18 is rotated, the valve shaft 25 rotates relative to the seal portion 34a of the seal member 34.

Therefore, it is preferable that the surface of the seal portion 34a of the seal member 34 be covered with a tetrafluoroethylene coating to reduce the frictional resistance with the valve stem 25.

As shown in FIG. 10, the width of the valve body 26 is slightly smaller than the diameter of the opening/closing insert insertion hole 17, and the lower end of the valve body 26 is arranged at a small distance from the bottom surface of the groove 19. .

On the other hand, as can be seen from Figures 2 and 3, the branch road 14
There is an engine cooling water passage 36 in the cylinder head 3 near the bottom.
is formed, and an exhaust port 8 is arranged near the side of the branch path 14.

Referring to FIG. 13, the tip of the arm 27 fixed to the upper end of the rotary valve 18 by a bolt 29 is connected via a connecting rod 43 to a control rod 42 fixed to a diaphragm 41 of a negative pressure diaphragm device 40. Ru.

The negative pressure diaphragm device 40 has a negative pressure chamber 44 isolated from the atmosphere by a diaphragm 41.
A compression spring 45 for pressing the diaphragm is inserted therein.

An intake manifold 47 equipped with a compound carburetor 46 consisting of a primary carburetor 46a and a secondary carburetor 46b is attached to the cylinder head 3, and the negative pressure chamber 44 is connected to the intake manifold 47 via a negative pressure conduit 48. connected within.

A check valve 49 is inserted into the negative pressure conduit 48 and allows flow only from the negative pressure chamber 44 into the intake manifold 47 .

Further, the negative pressure chamber 44 communicates with the atmosphere via an atmosphere conduit 50 and an atmosphere release control valve 51.

This atmospheric release control valve 51 has a negative pressure chamber 53 and an atmospheric pressure chamber 54 separated by a diaphragm 52, and further has a valve chamber 55 adjacent to the atmospheric pressure chamber 54.

This valve chamber 55 is connected to the negative pressure chamber 4 via an atmospheric conduit 50 on the one hand.
4 and, on the other hand, to the atmosphere via a valve port 56 and an air filter 57.

Inside the valve chamber 55 is a valve body 58 that controls opening and closing of the valve boat 56.
The valve body 58 is connected to the diaphragm 52 via a valve rod 59.

A compression spring 60 for pressing the diaphragm is inserted into the negative pressure chamber 53, and the negative pressure chamber 53 is further connected to a venturi portion 62 of the primary side carburetor 46a via a negative pressure conduit 61.

The carburetor 46 is a commonly used carburetor, and when the primary throttle valve 63 opens a predetermined opening degree or more, the secondary throttle valve 64 opens, and when the primary throttle valve 63 fully opens, the secondary throttle valve 64 opens. The side throttle valve 64 is also fully opened.

The negative pressure generated in the venturi portion 62 of the primary side carburetor 46a increases as the amount of intake air supplied into the engine cylinder increases, and therefore the negative pressure generated in the venturi portion 62 becomes larger than a predetermined negative pressure. When the engine is operated at high speed and high load, the diaphragm 52 of the atmospheric release control valve 51 moves to the right against the compression spring 60, and as a result, the valve body 58
opens the valve port 56 to open the negative pressure chamber 44 of the negative pressure diaphragm device 40 to the atmosphere.

At this time, the diaphragm 41 is moved downward by the spring force of the compression spring 45, and as a result, the rotary valve 18 is rotated and the branch passage 14 is fully opened.

On the other hand, when the opening degree of the primary throttle valve 63 is small, the negative pressure generated in the venturi part 62 is small, so the diaphragm 52 of the atmospheric release control valve 51 moves to the left by the spring force of the compression spring 60, and the valve body 58 closes valve port 56.

Furthermore, when the opening degree of the primary throttle valve 63 is small as described above, a large negative pressure is generated within the intake manifold 47.

The check valve 49 opens when the negative pressure in the intake manifold 47 becomes larger than the negative pressure in the negative pressure chamber 44 of the negative pressure diaphragm device 40, and the negative pressure in the intake manifold 47 becomes the negative pressure in the negative pressure chamber 44. Since the valve closes when it becomes smaller than , the negative pressure in the negative pressure chamber 44 is maintained at the maximum negative pressure generated in the intake manifold 47 as long as the atmospheric release control valve 51 is closed.

When negative pressure is applied to the negative pressure chamber 44, the diaphragm 41 rises against the compression spring 45, and as a result, the rotary valve 18 is rotated and the branch passage 14 is closed.

Therefore, when the engine is operating at low speed and low load, the rotary valve 18 closes the branch passage 14.

Furthermore, even during high-load operation, if the engine speed is low,
Furthermore, even if the engine speed is high, when the engine is operating under low load, the atmospheric release control valve 51 remains closed because the negative pressure generated in the venturi portion 62 is small.

Therefore, during such low-speed, high-load operation and high-speed, low-load operation, the negative pressure in the negative pressure chamber 44 is maintained at the aforementioned maximum negative pressure, so the branch passage 14 is closed by the rotary valve 18.

As mentioned above, the rotary valve 18 shuts off the branch passage 14 when the engine is operating at low speed and low load with a small amount of intake air.

At this time, the air-fuel mixture sent into the inlet passage part A descends inside the swirl part B while swirling along the upper wall surface 13 of the swirl part B, and then flows into the combustion chamber 4 while swirling.
A strong swirling flow is generated inside.

On the other hand, when the engine is operated at high speed and under high load with a large amount of intake air, the rotary valve 18 opens, so that part of the air-fuel mixture sent into the inlet passage A flows into the volute part B via the branch passage 14 with low flow resistance. sent to.

As mentioned above, the upper edge of the outlet opening 16 of the branch passage 14 is connected flush with the soil wall surface 13 of the spiral part B, so that the air-fuel mixture flowing out from the branch passage 14 flows along the upper wall surface 13 of the spiral part B. It collides head-on with the swirling total air mixture flow and decelerates the total air mixture flow along the upper wall surface 13 of the swirl portion B.

That is, among the swirling flows generated in the swirling portion B, the swirling flow along the upper wall surface 13 of the swirling portion B is the strongest, and the entire air mixture flow having this strong swirling force is decelerated.

Moreover, since the peripheral edge of the valve body 26 of the rotary valve 1B is formed in a model cross-sectional shape, the flow resistance due to the valve body 26 is small, and therefore the flow velocity of the air-fuel mixture flowing out from the outlet opening 16 of the branch passage 14 can be increased. Therefore, the deceleration effect of the swirling flow becomes even stronger.

In this manner, when the rotary valve 18 opens during engine high-speed, high-load operation, not only does the overall flow path area increase, but also the total air mixture flow, which has a strong swirling force, is decelerated, thereby widening the swirling flow. Since it is weakened, high filling efficiency can be ensured.

Further, as described above, by providing the inclined surface 16a, a part of the air-fuel mixture fed into the inlet passage A is given a downward force, and as a result, the air-fuel mixture is moved to the lower wall of the inlet passage A without swirling. Since the fluid flows into the spiral portion B along the curve, the inflow resistance becomes small, thus making it possible to further improve the filling efficiency during high-speed, high-load operation.

As mentioned above, when the engine is operating at low speed and low load, the rotary valve 18
fully closes the branch passage 14, but at this time, if fuel accumulates in the branch passage 14 upstream of the rotary valve 18, the accumulated fuel is sent into the engine cylinder when the rotary valve 18 opens. There is a problem in that the supplied air-fuel mixture temporarily becomes too rich, thus worsening exhaust emissions.

However, in the present invention, as shown in FIG. 10, a gap is formed between the lower end of the valve body 26 and the bottom surface of the concave groove 19, so the air-fuel mixture passes through this gap and enters the spiral part B, although in a small amount. In this way, fuel can be prevented from accumulating.

Further, due to the arrangement of the rotary valve 18, it is necessary to provide a groove 19. If such a groove 19 is provided, the groove 1
Fuel tends to accumulate inside 9.

However, in the present invention, since the engine cooling water passage 36 and the exhaust port 8 are arranged near the branch passage 14 as described above, the bottom surface of the groove 19 is heated by the cooling water and exhaust gas, and thus the groove 19 Since the vaporization of the fuel inside can be promoted, fuel accumulation can be suppressed.

As described above, according to the present invention, since the peripheral edge of the valve body of the rotary valve is formed in a model cross-sectional shape, the flow resistance due to the rotary valve is small, and thus when the rotary valve opens, the air-fuel mixture is It can be made to flow out from the branch outlet opening at high speed.

In the present invention, the upper end edge of the outlet opening of the branching passage is connected flush with the upper wall surface of the volute, so that the air-fuel mixture flowing out at high speed generates a strong swirling force along the soil wall surface of the volute. The entire swirling air mixture is greatly decelerated.

As a result, the swirling flow is greatly weakened, making it possible to obtain high filling efficiency.

[Brief explanation of drawings]

Fig. 1 is a plan view of an internal combustion engine according to the present invention, and Fig. 2 is a plan view of an internal combustion engine according to the present invention.
A cross-sectional view taken along the line ■-■ in the figure, Figure 3 is the ■■ of Figure 2.
4 is a perspective view showing the shape of the helical intake port, 5 is a plan view of 4, and 6 is a cross-sectional view taken along the line -■. Figure 7 is a cross-sectional view taken along line ■-■ in Figure 5, Figure 8 is a cross-sectional view taken along line ■-■ in Figure 5, and Figure 9 is a cross-sectional view taken along line ■-■ in Figure 5. FIG. 10 is a side sectional view of the rotary valve, FIG. 11 is a side view of FIG. 10, and FIG.
13 is a plan view of the positioning ring, FIG. 13 is an overall view of the flow path control device, and FIG. 14 is a sectional view taken along line XIV-XIV in FIG. 10. 5...Intake valve, 6...Helical intake port, 14...Branch path, 18...Rotary valve, 25...Valve Shaft, 26... Valve body.

Claims (1)

[Scope of utility model registration request] A helical intake port is formed of a spiral portion formed in the intake valve body and an inlet passage portion that is tangentially connected to the spiral portion and extends substantially straight. The outlet opening of the branch passage communicates with the spiral terminal end of the spiral section, and the exit opening is formed at the upper end of the side wall surface of the spiral section so as to face the swirling flow along the upper wall surface of the spiral section. The upper end edge is connected flush to the upper wall surface of the spiral part, an on-off valve insertion hole extending across the branch path is formed in the cylinder head, and a rotary valve holder equipped with a rotary valve is inserted into the on-off valve insertion hole. A flow path control device for a helical intake port, in which a valve body inserted into the rotary valve and fixed to the rotary valve shaft is arranged in the branch passage, and the peripheral edge of the valve body has a model cross-sectional shape.