JPS6238540B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a helical intake port.

A helical intake port typically consists of a spiral formed around the intake valve and an inlet passageway tangentially connected to the spiral and extending generally straight. If you try to use such a helical intake port to generate a strong swirling flow in the combustion chamber of the engine during low-speed, low-load engine operation with a small amount of intake air, the shape of the intake port will have a large flow resistance. A problem arises 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 path is formed in the cylinder head that branches from the helical type intake port inlet passage and communicates with the spiral end of the helical type intake port spiral part, and an on-off valve is installed in the branch path. The applicant has already proposed a helical intake port in which an on-off valve is opened during high-speed, high-load engine operation. In this helical type intake port, when the engine is operated at high speed and under high load, a 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 a branch path, so the intake air flow path is The cross-sectional area can be increased, thus improving the filling efficiency. However, in this helical intake port, the branch passage is formed as a cylindrical passage completely independent from the inlet passage, so the flow resistance of the branch passage is relatively large, and the branch passage is formed adjacent to the inlet passage. This limits the cross-sectional area of the inlet passage, making it difficult to obtain a sufficiently high filling efficiency. Furthermore, the helical intake port itself has a complicated shape, and if a branch passage that is completely independent from the inlet passage is added, the overall structure of the intake port will become extremely complicated. It is quite difficult to form a helical intake port in the cylinder head.

SUMMARY OF THE INVENTION The present invention provides a helical intake port that is capable of achieving high filling efficiency during high-speed, high-load engine operation and has a novel shape that is easy to manufacture.

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

Referring to FIGS. 1 and 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, and 4 is a piston 2 and a cylinder head 3. A combustion chamber is formed in between, 5 is an intake valve,
6 is a helical intake port formed in the cylinder head 3, 7 is an exhaust valve, and 8 is a cylinder head 3.
Reference numeral 9 indicates an ignition plug disposed within the combustion chamber 4, and reference numeral 10 indicates a stem guide for guiding the stem 5a of the intake valve 5. As shown in FIGS. 1 and 2, the upper wall surface 1 of the intake port 6
A partition wall 12 projecting downward is integrally molded on top of the helical intake port 6, which includes a spiral portion B and an inlet passage portion A connected to the spiral portion B. This partition wall 12 extends in the flow direction of the intake air flow from inside the inlet passage section A to around the stem guide 10 of the intake valve 5, and as can be seen from FIG. It gradually becomes wider as it approaches the stem guide 10 from part A. The bulkhead 12 has a tip 13 located on the side closest to the inlet opening 6a of the intake port 6, and the bulkhead 12 further has a first side wall surface extending counterclockwise from the tip 13 to the stem guide 10 in FIG. 14a, and a second side wall surface 14b extending clockwise from the distal end portion 13 to the stem guide 10. The first side wall surface 14a is the tip portion 1
3 to the spiral part B passing through the side of the stem guide 10.
The spiral portion side wall surface 15 extends to the vicinity of the side wall surface 15 of the spiral portion.
A narrowed portion 16 is formed between the two. Next, the first side wall surface 14a extends to the stem guide 10 while being curved so as to be gradually spaced apart from the spiral portion side wall surface 15. On the other hand, the second side wall surface 14b extends almost straight from the distal end portion 13 to the stem guide 10.

Referring to FIGS. 1 to 9, the inlet passage section A
The side wall surfaces 17, 18 of are arranged substantially vertically, while the upper wall surface 19 of the inlet passage section A gradually descends towards the spiral section B. The side wall surface 17 of the inlet passage section A extends immediately on a tangent to the peripheral edge of the intake valve 5 to form a spiral section B.
is connected to the side wall surface 15 of. Side wall surface 1 of spiral part B
5 bulges outward from the peripheral edge of the intake valve 5,
Therefore, the side wall surface 17 of the inlet passage section A and the side wall surface 15 of the spiral section B are connected at a certain angle at their connection portion. In addition, the side wall surface 1 of the inlet passage section A
8 has a convex shape that bulges inward as shown in FIG. On the other hand, the upper wall surface 19 of the inlet passage section A is smoothly connected to the upper wall surface 20 of the spiral section B, and the upper wall surface 20 of the spiral section B extends from the connection section between the spiral section B and the entrance passage section A toward the narrowing section 16. It gradually narrows in width while descending, and then gradually widens as it passes through the narrowing part 16. On the other hand, as shown in FIG. 5, the bottom wall surface 21 of the inlet passage A is almost horizontal in its entirety in the vicinity of the inlet opening 6a, and the bottom wall surface portion 21a adjacent to the side wall surface 17 is as shown in FIG. As shown, as it approaches the spiral portion B, it rises to form an inclined surface. The angle of inclination of this inclined bottom wall surface portion 21a gradually increases as it approaches the spiral portion B.

On the other hand, the first side wall surface 14a of the partition wall 12 is a slightly downwardly inclined surface, and the second side wall surface 14b is substantially vertical. Bottom wall surface 22 of partition wall 12
descends from the inlet passage A toward the spiral part B while slightly curving so that the distance from the upper wall surface 11 of the inlet passage 6 gradually increases from the tip 13 toward the stem guide 10. A rib 23 is formed on the bottom wall surface 22 of the partition wall 12 in a region indicated by hatching in FIG. do.

On the other hand, a branch passage 24 is provided in the cylinder head 3 that communicates the spiral end C of the spiral portion B with the inlet passage A.
is formed, and a rotary valve 25 serving as an on-off valve is disposed at the inlet of this branch path 24. This branch passage 24 is separated from the inlet passage part A by the partition wall 12, and the entire lower space of the branch passage 24 communicates with the inlet passage part A. Upper wall surface 2 of branch road 24
6 has a substantially uniform width and gradually descends toward the end C of the spiral and is smoothly connected to the upper wall surface 20 of the spiral B. A side wall surface 27 of the branching passage 24 facing the second side wall surface 14b of the partition wall 12 is a slightly inclined downward slope, and furthermore, this side wall surface 27 is located approximately on an extension of the side wall surface 18 of the inlet passage section A. do. The intersection line between the side wall surface 27 and the bottom wall 21, that is, the bottom wall 2
One side edge of the intake valve 1 extends so as to be in contact with the peripheral edge of the intake valve 5 as shown by the broken line P in FIG. It sticks out. It can be seen from FIG. 2 that the width of the bottom wall surface 21 is approximately equal to the diameter of the intake valve 5, and that both side edges of the bottom wall surface 21 are located on tangents to the peripheral edge of the intake valve 5.

As shown in FIG. 10, the rotary valve 25 is composed of a rotary valve holder 28 and a valve shaft 29 rotatably supported within the rotary valve holder 28. The screw hole 30 is screwed into the screw hole 30. A thin plate-shaped valve body 31 is integrally formed at the lower end of the valve shaft 29, and as shown in FIG.
1 extends from the top wall surface 26 of the branch path 24 to the bottom wall surface 21. On the other hand, an arm 32 is attached to the upper end of the valve shaft 29.
is fixed. Further, a ring groove 33 is formed on the outer peripheral surface of the valve shaft 29, and an E-shaped positioning ring 34 is fitted into the ring groove 33. Furthermore, a sealing member 35 is provided at the upper end of the rotary valve holder 28.
is fitted, and this sealing member 35 connects the valve shaft 2.
9 sealing action is performed.

Referring to FIG. 11, the tip of the arm 32 fixed to the upper end of the rotary valve 25 is connected via a connecting rod 43 to a control rod 42 fixed to a diaphragm 41 of a negative pressure diaphragm device 40. As shown in FIG. The negative pressure diaphragm device 40 has a negative pressure chamber 44 isolated from the atmosphere by a diaphragm 41, and a compression spring 45 for pressing the diaphragm is inserted into the negative pressure chamber 44. 1 for cylinder head 3
An intake manifold 47 equipped with a compound type carburetor 46 consisting of a next side carburetor 46a and a secondary side carburetor 46b is attached, and the negative pressure chamber 44 is connected to a negative pressure conduit 48.
The intake manifold 47 is connected through the intake manifold 47 . 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 diaphragm 52
It has a negative pressure chamber 53 and an atmospheric pressure chamber 54 separated by a spacer, and further has a valve chamber 55 adjacent to the atmospheric pressure chamber 54. This valve chamber 55 communicates on the one hand with the negative pressure chamber 44 via an atmospheric conduit 50 and on the other hand with the atmosphere via a valve port 56 and an air filter 57. A valve body 58 for controlling the opening and closing of the valve port 56 is provided within the valve chamber 55, and the valve body 58 is connected to the diaphragm 52 via a valve rod 59.
A compression spring 6 for pressing the diaphragm is provided in the negative pressure chamber 53.
Further, the negative pressure chamber 53 is connected to the bench lily portion 62 of the primary side carburetor 46a via a negative pressure conduit 61.

The vaporizer 46 is a commonly used vaporizer.
When the downstream throttle valve 63 opens to 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 also fully opens. The negative pressure generated in the bench lily 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 bench lily portion 62 becomes larger than a predetermined negative pressure. diaphragm 52 of the atmospheric release control valve 51 when the engine is operating at high speed and high load.
moves to the right against the compression spring 60, and as a result, the valve body 58 opens the valve port 56 and opens 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 25 is rotated and the branch passage 24 is fully opened. On the other hand 1
When the opening degree of the next throttle valve 63 is small, the negative pressure generated in the bench lily 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 Close port 56. Sometimes, when the opening degree of the primary throttle valve 63 is small, 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 larger than the negative pressure in the negative pressure chamber 44. Since the valve closes when the pressure becomes smaller than the pressure, 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 within the negative pressure chamber 44, the diaphragm 41 rises against the compression spring 45, and as a result, the rotary valve 25 is rotated and the branch passage 24 is closed. Therefore, when the engine is operating at low speed and low load, the branch passage 24 is closed by the rotary valve 25. Note that when the engine speed is low even during high-load operation, or when low-load operation is performed even when the engine speed is high, the negative pressure generated in the bench lily portion 62 is small, so that it is not opened to the atmosphere. Control valve 51 remains closed. 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 that the rotary valve 25
Branch road 24 is closed by.

As described above, the rotary valve 25 closes the branch passage 24 when the engine is operated at low speed and under low load with a small amount of intake air. At this time, part of the air-fuel mixture sent into the inlet passage A travels along the upper wall surfaces 19 and 20 as shown by arrow R in FIGS. 1 and 2, and part of the remaining air-fuel mixture The mixture of parts is the first
As shown by arrow S in the drawings and FIG. 2, it changes direction toward the side wall surface 17 of the inlet passage section A before the rotary valve 25, and then proceeds along the side wall surface 15 of the spiral section B. As mentioned above, the widths of the upper wall surfaces 19 and 20 gradually become narrower as they approach the narrowed portion 16, so the flow path for the air-fuel mixture flowing along the upper wall surfaces 19 and 20 gradually becomes narrower, and thus the upper Wall surfaces 19, 20
The speed of the air mixture along is gradually increased. Furthermore, as described above, since the first side wall surface 14a of the partition wall 12 extends to the vicinity of the side wall surface 15 of the spiral portion B, the air mixture flowing along the upper wall surfaces 19 and 20 flows onto the side wall surface 15 of the spiral portion B. A strong swirling flow is generated in the spiral portion B because the fluid is pushed away and then proceeds along the side wall surface 15 as shown by the arrow T in FIGS. 1 and 2. Next, the air-fuel mixture swirls and flows into the combustion chamber 4 through the gap formed between the intake valve 5 and its valve seat, generating a strong swirling flow within the combustion chamber 4.

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 25 opens, so the inlet passage A
The air-fuel mixture sent into the tank is divided into three main streams. That is, the first flow flows between the first side wall surface 14a of the partition wall 12 and the side wall surface 17 of the inlet passage section A as shown by the arrow X in FIGS. 3 and 4, and then flows into the upper wall surface of the spiral section A. 20, the second flow is a mixture flow that flows into the swirl portion B via the branch path 24 as shown by the arrow Y in FIGS. 3 and 4, The third flow is a mixed air flow that flows into the swirl section B along the bottom wall surface 21 of the inlet passage section A, as shown by arrow Z in FIG. The flow resistance of the branch portion 24 is smaller than the flow resistance between the first side wall surface 14a and the side wall surface 17, and therefore the second air mixture flow Y
is larger than the first air mixture flow X. Furthermore,
As shown in FIG. 3, the flow direction of the first mixed air flow X flowing while swirling in the swirl portion B is deflected downward by the second mixed air flow Y, thus increasing the swirling force of the first mixed air flow. It will be weakened. In this way, the mixed air flow from the branch passage 24 with low flow resistance is increased, and the flow direction of the first mixed air flow is further deflected downward, so that high filling efficiency can be obtained. Further, as described above, the bottom wall surface 22 of the partition wall 12
is formed from a downwardly inclined surface, the third air mixture flow is guided by this inclined surface and the flow direction is deflected downward, and the side wall surface 27 of the branch passage 24 downstream of the rotary valve 25 is formed with a downwardly inclined surface. Since it is formed from a surface, the flow direction of the second air mixture flow is also deflected downward, thus making it possible to obtain even higher filling efficiency.

In order to increase the filling efficiency, it is necessary to make the flow resistance of the intake port 6 as small as possible. It is necessary to minimize the change in cross-sectional area along the line. There is no need to explain that the flow resistance of the intake port 6 is reduced if the intake port 6 is formed immediately. On the other hand, according to the theory of fluid mechanics, when the cross-sectional area of the flow increases, the velocity distribution becomes uniform, but the pressure increases. Therefore, if the pressure difference between the inlet and outlet of the intake port 6 is constant, the cross-sectional area of the flow is equal to that of the intake port 6.
If the inside of the intake port 6 is enlarged, the flow rate will decrease, that is, the flow resistance of the intake port 6 will increase. Furthermore, if this expanded cross-sectional area is narrowed, a throttling loss will occur and the flow resistance will further increase. Therefore, in order to reduce the flow resistance of the intake port 6, it is necessary to minimize the change in the cross-sectional area of the intake port 6 along the axis. Therefore, the filling efficiency is highest when the intake port 6 is a so-called straight port with a straight, uniform cross section.
In the helical intake port 6 according to the present invention, the partition wall 2
1 protrudes, the flow resistance is inevitably greater than that of a straight port, but even in the helical type intake port 6 according to the present invention, the rotary valve 25
When the valve is opened, the axis of the intake port 6 becomes straight, and if the cross-sectional area change along the axis of the intake port 6 is made as small as possible, the flow resistance can be made close to that of a straight port. Therefore, in the helical type intake port 6 according to the present invention, as can be seen from FIG. The intake port 6 is formed such that the axis thereof passes through the intake valve stem 5a. On the other hand, referring to FIG. 12, the cross-sectional area S at each cross-section a, b, c, d, e, and f of the intake port 6 is shown. It can be seen from FIG. 12 that the cross-sectional area at each cross-section a, b, c, and d is approximately equal to the cross-sectional area at cross-section f of the air-fuel mixture outlet throat portion G, except for cross-section e at the spiral portion. Experiments have shown that among these cross sections a, b, c, d, e, and f, the cross-sectional area at the downstream end of the inlet passage shown by cross section d has the greatest effect on filling efficiency, that is, engine output. are doing. This experimental result is the first
Shown in Figure 3. In Fig. 13, the vertical axes Ps and T indicate the maximum output and torque of the engine, and the horizontal axis is the cross section d.
The ratio Ad/Af of the cross-sectional area Ad at cross-section f and the cross-sectional area Af at cross-section f is shown. Also, in Fig. 13, the solid line indicates the maximum output Ps during high-speed full-load operation.
The relationship between Ad/Af is shown, and the broken line shows the relationship between torque T and Ad/Af during low speed full load operation.
From Figure 13, in order to obtain high maximum output Ps and torque T, Ad/Af should be in the range of 0.9 to 1.1, that is, Ad and
It can be seen that it is necessary to make Af approximately equal. In this way, according to the present invention, the rotary valve 2
The intake port 6 is formed so that the axis of the intake port 6 when the intake valve 5 is opened extends immediately through the intake valve stem 5a, and both side edges of the bottom wall surface 21 of the intake port 6 are connected to the peripheral edge of the intake valve 5. The intake port 6 is formed so as to be in contact with the straight port so that the intake port 6 has a shape similar to that of a straight port. As a result, there is a partition wall 1 in the intake port 6 to generate a strong swirling flow.
Even if 2 is made to protrude, high filling efficiency can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an internal combustion engine according to the present invention taken along the line - in FIG. 2, FIG. 2 is a plan sectional view taken along the line - in FIG. 1, and FIG. FIG. 4 is a side view schematically showing the shape of the helical intake port, FIG. 4 is a plan view schematically showing the shape of the helical intake port, and FIG. 5 is a view taken along the - line in FIGS. 3 and 4. 6 is a sectional view taken along the - line in FIGS. 3 and 4, FIG. 7 is a sectional view taken along the - line in FIGS. 3 and 4, and FIG. 8 is a sectional view taken along the - line in FIGS. 3 and 4, FIG. 9 is a sectional view taken along the line - in FIGS. 3 and 4, and FIG.
Figure 0 is a side sectional view of the rotary valve, Figure 11 is a diagram showing the drive control device of the rotary valve, Figure 12 is a diagram showing the cross-sectional area of each cross section of the intake port, and Figure 13 is a diagram showing the cross-sectional area of each cross section of the intake port.
The figure shows the maximum output and torque of the engine. 4... Combustion chamber, 6... Helical intake port,
12... Bulkhead, 24... Branch, 25... Rotary valve.

Claims (1)

[Claims] 1. In a helical intake port configured by a spiral portion formed around the intake valve and an inlet passage connected tangentially to the spiral portion and extending almost straight, the helical intake port projects downward from the upper wall surface of the intake port. A partition wall extending in the flow direction of the intake air flow is formed in the intake port, an inlet passage portion and a branch passage branching from the inlet passage portion are formed on both sides of the partition wall, and an inlet passage portion and a branch passage are formed below the partition wall. A lower space communicating with the branch passage is formed, and a branch passage is communicated with the spiral terminal end of the spiral part, and an on-off valve is provided in the branch passage, and the intake air flow flowing through the branch passage is controlled by the on-off valve. ,
Further, the width of the intake port bottom wall surface common to the inlet passage and the branch path is made approximately equal to the diameter of the intake valve, and both side edges of the intake port bottom wall surface are extended in the tangential direction of the intake valve peripheral edge to form a spiral portion. A helical intake port with a side wall that bulges outward from the periphery of the intake valve.