JPS6350527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flow path control device for a helical intake port used in an internal combustion engine.

BACKGROUND OF THE INVENTION A helical intake port typically consists of a spiral formed around an intake valve and an inlet passageway tangentially connected to the spiral 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 during low-speed, low-load operation of the engine 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, high load, and with a large amount of air. To solve this problem, a branch path 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 section, 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 engine load operation. In this helical type intake port, during high engine load operation, a part of the intake air sent into the helical type intake port inlet passage is sent into the helical type intake port volute via the branch path, resulting in a break in the intake air flow path. The area can be increased and thus the filling efficiency can be improved.
However, with this helical type intake port, the opening/closing valve is closed during engine high-speed, low-load operation, so the flow path area of the intake port is narrow, and thus high filling efficiency cannot be obtained, making it difficult to obtain high engine output. The problem is that there is no. On the other hand, when the engine is operated at low speed and under high load, where knocking is likely to occur, the on-off valve is open, so a strong swirling flow cannot be obtained, and thus the combustion speed cannot be sufficiently increased, resulting in knocking. There is.

Purpose of the Invention The present invention is a helical type fuel pump that improves engine output by increasing charging efficiency not only during high-speed, high-load engine operation, but also during engine high-speed, low-load operation, and suppresses the occurrence of knocking during low-speed, high-load engine operation. Its purpose is to provide an intake port.

Structure of the Invention The structure of the present invention provides a helical intake port configured of a spiral portion formed around an intake valve and an inlet passage portion connected tangentially to the spiral portion and extending almost straight. A partition wall protruding downward from the upper wall surface and 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 is formed below the partition wall. A lower space is formed that communicates the passage section with the branch passage, and the branch passage is connected to the end of the spiral of the spiral part, and an on-off valve that responds to the engine speed and engine load is placed in the branch passage to reduce the engine load. is larger than a predetermined set load, the on-off valve is opened when the engine speed becomes higher than the predetermined first set speed, and when the engine load is smaller than the set load, the on-off valve is opened. The on-off valve is opened when the engine speed becomes higher than a second set speed which is higher than the first set speed.

Embodiment 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. A combustion chamber formed between the heads 3, 5 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 the top of the helical intake port 6 consisting of a spiral portion B and an inlet passage portion A connected to the spiral portion B in a connected manner. be done. 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. From part A to stem guide 10
It gradually becomes wider as it approaches. 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 the tip 1
3 and a second side wall surface 14b extending clockwise from 3 to the stem guide 10. The first side wall surface 14a extends from the distal end portion 13 through the side of the stem guide 10 to the vicinity of the side wall surface 15 of the spiral portion B, and forms a narrow portion 16 between the first side wall surface 14a and the spiral portion side wall surface 15. Next, the first side wall surface 14a is curved so as to be gradually spaced apart from the spiral portion side wall surface 15, and the first side wall surface 14a is connected to the stem guide 10.
Extends to. On the other hand, the second side wall surface 14b is
3 to the stem guide 10 almost immediately.

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 is smoothly connected to the side wall surface 15 of the spiral section B, and the upper wall surface 19 of the entrance passage section A is smoothly connected to the upper wall surface 20 of the spiral section B. The upper wall surface 20 of the spiral part B
The width gradually narrows while descending from the connecting part of the inlet passage part A toward the narrowed part 16, and then, after passing through the narrowed part 16, the width gradually widens. On the other hand, the bottom wall surface 21 of the inlet passage section 6 has an inlet opening 6 as shown in FIG.
The entire surface is substantially horizontal in the vicinity of point a, and the bottom wall surface portion 21a adjacent to the side wall surface 17 rises as it approaches the spiral portion B to form an inclined surface, as shown in FIG.

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 2 of partition wall 12
2 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. Partition wall 12
A rib 23 is formed on the bottom wall surface 22 in a region shown by hatching in FIG. 4 and projects downward from the bottom wall surface 22, and the bottom surface of the rib 23 and the bottom wall surface 22 form a slightly curved inclined surface.

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 constituting an on-off valve is arranged 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 26 of branch road 24
has a substantially uniform width, gradually descends toward the spiral terminal end C, and is smoothly connected to the upper wall surface 20 of the spiral portion B. A side wall surface 27 of the branch path 24 facing the second side wall surface 14b of the partition wall 12 is substantially vertical;
Furthermore, this side wall surface 27 is located approximately on an extension of the side wall surface 18 of the inlet passage section A. As can be seen from FIG. 1, the rib 23 formed on the partition wall 12 extends from the vicinity of the rotary valve 25 toward 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 the valve shaft 2 is fitted by this seal member 35.
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. An intake manifold 47 having a carburetor 46 is fixed to the cylinder head 3, and a negative pressure chamber 44 of a negative pressure diaphragm device 40 is connected to a negative pressure tank 38 via a negative pressure conduit 48. This negative pressure tank 38 is connected to the intake manifold 47 via a check valve 39, and thus the inside of the negative pressure tank 38 is maintained at the maximum negative pressure generated in the intake manifold 47. A solenoid operated switching valve 49 is inserted into the negative pressure conduit 48, and this switching valve 4
9 cuts off communication between the negative pressure chamber 44 and the negative pressure tank 38 to open the negative pressure chamber 44 to the atmosphere when the solenoid is energized. This switching valve 49 is connected to an output terminal of an electronic control unit 50. On the other hand, an input terminal of the electronic control unit 50 is connected to a throttle switch 52 for detecting engine load, which responds to the carburetor throttle valve 51, and a rotation speed switch 53, which responds to the engine rotation speed. The rotation speed switch 53 is equipped with four output terminals a, b, c, and d, and these output terminals a, b, c, and d correspond to the engine rotation speed, respectively.
It becomes high level when it reaches 4000r.pm or more, 3600r.pm or more, 1900r.pm or more, and 1700r.pm or more. Output terminal a is connected to S- via inverter 54.
It is connected to the set input terminal S of the R flip-flop 55, and the output terminal b is connected to the set input terminal S of the S-R flip-flop 55.
It is connected to the reset input terminal R of No.5. Further, the output terminal c is connected to the set input terminal S of the S-R flip-flop 57 via the inverter 56.
Output terminal d is connected to reset input terminal R of S-R flip-flop 57. On the other hand, the throttle switch 52 includes a pair of output terminals e and f,
These output terminals e and f are connected to the throttle valve 51, respectively.
The high level occurs when the opening angle of the valve is 40° or more and 35° or more relative to the fully closed position. Output terminal e is connected to S-R flip-flop 5 via inverter 58.
The output terminal f is connected to the reset input terminal R of the S-R flip-flop 59. Each S-R flip-flop 5
5, 57, and 59 are set by the fall of the input voltage applied to the set input terminal S, and at this time, the output terminal Q of each S-R flip-flop 55, 57, and 59 becomes high level. On the other hand, each S-R flip-flop 55, 57, 59 is reset by the fall of the input voltage applied to the reset input terminal R, and at this time each flip-flop 55, 57, 59 is reset.
The output terminals Q of 57 and 59 become low level. The electronic control unit 50 is an S-R flip-flop 57.
AND gate 6 which takes the output of S-R flip-flop 59 as one input and the output of S-R flip-flop 59 as the other input.
0 and an OR gate 61 which takes the output of the S-R flip-flop 55 as one input and the output of the AND gate 60 as the other input, and the output terminal of the OR gate 61 is connected to the switching valve 49 via a power amplifier 62. Connected to the solenoid.

As you can see from Figure 11, the engine speed is 4000r.
When it becomes higher than pm, the output terminal a of the rotation speed switch 53 becomes high level, and as a result, the inverter 5
Due to the fall of the output voltage of 4, the S-R flip 5
5 is set, the output terminal Q of the S-R flip-flop 55 goes high. At this time, the solenoid of the switching valve 49 is energized, and the negative pressure chamber 44 of the negative pressure diaphragm device 40 is opened to the atmosphere. When the negative pressure chamber 44 is opened to the atmosphere, the diaphragm 41 moves toward the rotary valve 25 by the spring force of the compression spring 45, and as a result, the rotary valve 25 is rotated and the rotary valve 25 is moved toward the branch path 24. Open the door. On the other hand, the engine speed is 3600r.pm
When the number of rotations becomes lower than that, the output terminal b of the rotation speed switch 53 becomes a low level, so that the S-R flip-flop 55 is reset, and the output terminal Q of the S-R flip-flop 55 becomes a low level. Thus, at this time, the solenoid of the switching valve 49 is deenergized, and since the negative pressure chamber 44 is connected to the negative pressure tank 38, negative pressure is applied within the negative pressure chamber 44. As a result, the diaphragm 41 moves toward the negative pressure chamber 44 against the compression spring 45, so that the rotary valve 25 is rotated and the rotary valve 25 closes the branch passage 24.

On the other hand, when the engine speed becomes 1900 rpm or more and the opening degree of the throttle valve 51 becomes 40° or more, S-
The R flip-flops 57 and 59 are set together, and as a result, the output terminal of the AND gate 60 goes high and the solenoid of the switching valve 49 is energized, thereby opening the rotary valve 25. In this way, even if the engine speed is 3600r.pm or less, if the engine speed is 1900r.pm or more and the opening degree of the throttle valve 51 is 40° or more, the rotary valve 2
5 is forced to open. On the other hand, the engine speed
When the voltage becomes less than 1700 rpm, both the output voltages of the S-R flip-flops 55 and 57 become low levels, so the solenoid of the switching valve 49 is deenergized, and the rotary valve 25 is opened. On the other hand, when the opening degree of the throttle valve 51 is less than 35 degrees, the S-R flip-flop 59 is reset and the output voltage of the AND gate 60 is at a low level, so even if the engine speed slightly exceeds 1900 rpm. The rotary valve 25 continues to be closed, but at this time, when the engine speed becomes higher than 4000 rpm, the S-R flip-flop 55 is set and the OR gate 61 is closed.
The output voltage becomes a high level, and thus the rotary valve 25 is opened. Therefore, rotary valve 2
The opening/closing state of the valve No. 5 is as shown in FIG. That is, when the engine speed N and the throttle valve opening P reach the hatched area above the solid line in FIG. 12, the rotary valve 25 opens and the engine speed N
When the throttle valve opening degree P reaches a hatched region below the broken line, the rotary valve 25 closes. The region between the solid line and the broken line in FIG. 12 is a so-called hysteresis region in which the rotary valve 25 maintains its previous state.

As can be seen from Figure 12, when the engine is running at low speed and low load, and when the engine is running at low speed and high load, the rotary valve 2
5 closes the branch road 24. At this time, part of the air-fuel mixture sent into the inlet passage A advances along the upper wall surfaces 19 and 20, and part of the remaining air-fuel mixture collides with the rotary valve 25 and flows into the inlet passage. After changing its direction toward the side wall surface 17 of section A, it proceeds along the side wall surface 15 of 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 narrows, and thus the width of the upper wall surfaces The speed of the air mixture flow along lines 19 and 20 is gradually increased. Furthermore, as described above, the first part of the partition wall 12
Since the side wall surface 14a 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 is forced onto the side wall surface 15 of the spiral portion B.
Next, a strong swirling flow is generated within the swirl portion B to proceed along the side wall surface 15. Next, the mixture swirls and flows into the combustion chamber 4 through the gap formed between the intake valve 5 and its valve seat.
Generates a strong swirling flow inside. In this way, when the engine is operating at low speed and low load, a strong swirling flow flows into the combustion chamber 4.
The combustion is generated within the combustion chamber 4, accelerating the combustion rate, so stable combustion can be obtained, and even when the engine is operating at low speed and high load, a strong swirling flow is generated within the combustion chamber 4, accelerating the combustion rate, so that no knocking can be achieved. The occurrence of can be suppressed.

On the other hand, as shown in Fig. 12, the rotary valve 25 opens during engine high-speed, high-load operation and during engine high-speed, low-load operation, so the air-fuel mixture sent into the inlet passage A is roughly divided into three flows. Diverted. That is, the first flow flows through the first side wall surface 1 of the partition wall 12.
4a and the side wall surface 17 of the inlet passage section A, and then flows while swirling along the upper wall surface 20 of the spiral section A, and the second flow flows into the spiral section B via the branch passage 24. The third flow is a mixed air flow that flows into the swirl portion B along the bottom wall surface 21 of the inlet passage portion A. . Branch road 2
4 is smaller than the flow resistance between the first side wall surface 14a and the side wall surface 17, and therefore the second mixed air flow is larger than the first mixed air flow. Furthermore,
The flow direction of the first air mixture flowing while swirling in the swirl portion B is deflected downward by the second air mixture, thus weakening the swirling force of the first air mixture. In this way, the mixed air flow from the branch passage 24 with low flow resistance is increased, and the flow direction of the mixed air flow is further deflected downward, so that high filling efficiency can be obtained. Further, as mentioned above, since the bottom wall surface 22 of the partition wall 21 is formed from a downwardly inclined surface, the third mixed air flow is guided by this inclined surface and the flow direction is deflected downward, thus achieving an even higher filling. Efficiency will be gained.

Effects of the Invention A strong swirling flow can be generated in the combustion chamber not only when the engine is running at low speed and with a low load, but also when the engine is running at a low speed and with a high load, so it is possible to suppress the occurrence of knocking during low speed and high load operation. . In addition, high charging efficiency can be obtained not only during high-speed, high-load operation of the engine, but also during high-speed, low-load operation of the engine, so that high output torque can be obtained during high-speed, low-load operation. Furthermore, by forming a lower space below the partition wall, not only does the flow passage area increase when the rotary valve opens, but the entire lower space of the intake port becomes like a straight port. High charging efficiency can be obtained during engine high-speed, high-load operation with a large amount of intake air.

[Brief explanation of drawings]

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. 3 is a helical type intake A side view schematically showing the shape of the port,
Fig. 4 is a plan view schematically showing the shape of the helical intake port, and Fig. 5 is a -
6 is a sectional view taken along the - line of FIGS. 3 and 4; FIG. 7 is a sectional view taken along the - line of FIGS. 3 and 4; Figure 8 is a sectional view taken along the - line in Figures 3 and 4, Figure 9 is a sectional view taken along the - line in Figures 3 and 4, and Figure 10 is a side view of the rotary valve. A sectional view, FIG. 11 is a diagram showing a rotary valve drive control device, and FIG. 12 is a diagram showing the relationship between the engine rotational speed at which the rotary valve is opened or closed and the throttle valve opening. 4... Combustion chamber, 6... Helical intake port,
12... Bulkhead, 24... Diversion path, 25... Rotary valve, 52... Throttle switch, 53... Rotation speed switch.

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 branch passage is connected to the spiral end of the spiral part, and an on-off valve that responds to the engine speed and engine load is disposed within the branch passage, so that the engine load is predetermined. When the engine load is higher than the predetermined set load, the opening/closing valve is opened when the engine speed becomes higher than the predetermined first set speed, and when the engine load is smaller than the above set load, the engine is opened. A flow path control device for a helical intake port, which opens the on-off valve when the rotational speed becomes higher than a second set rotational speed that is higher than the first set rotational speed.