JPH034732B2 - - 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 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. 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 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 actuator is installed in the branch path. The main helical intake port flow path control device is a helical intake port flow path control device that is equipped with a normally-closed on-off valve that is operated by the engine, and operates an actuator to open the on-off valve when the amount of engine intake air becomes larger than a predetermined amount. This has already been proposed by the applicant (see Japanese Patent Application No. 56-51149 and Japanese Patent Publication No. 35535-1983).
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 has a problem in that when the amount of intake air decreases, the on-off valve is suddenly closed, resulting in sudden torque fluctuations, which deteriorates vehicle drivability.

The present invention provides a flow path control device for a helical intake port that gradually closes an on-off valve when the amount of intake air decreases, thereby slowing changes in torque and ensuring good vehicle drivability. It's about doing.

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 cylinder block 1, 3 is a cylinder head fixed on cylinder block 1, and 4 is a link between piston 2 and cylinder head 3. 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.
Exhaust ports formed therein are shown respectively. Although not shown in the figure, an ignition plug is disposed within the combustion chamber 4.

3 to 5 schematically show the shape of the helical intake port 6 of FIG. 2. This helical intake port 6 has a flow path axis a as shown in FIG.
It is composed of a slightly curved inlet passage part A and a spiral part B formed around the valve axis of the intake valve 5, and the inlet passage part A is tangentially connected to the spiral part B. As shown in FIGS. 3, 4, and 7, the side wall surface 9 of the inlet passage A near the spiral axis b
The upper side wall surface 9a is formed as an inclined surface facing downward, and the width of this inclined surface 9a becomes wider as it approaches the spiral portion B. As shown in the figure, the entire side wall surface 9 is formed into a downwardly oriented inclined surface 9a. The upper half of the side wall surface 9 is smoothly connected to the peripheral wall surface of a cylindrical projection 11 formed on the upper wall surface of the intake port around the intake valve guide 10 (FIG. 2).
The lower half of the spiral portion B is connected to the side wall surface 12 of the spiral portion B at the spiral end portion C of the spiral portion B. In addition, spiral part B
The upper wall surface 13 is connected to the downwardly inclined wall D at the spiral end C.

On the other hand, as shown in FIGS. 1 to 5, 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. Branch road 14
An inlet opening 15 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 at the upper end of the side wall surface 12 at the spiral end C. Furthermore, an on-off valve insertion hole 17 is provided in the cylinder head 3 and extends through the branch passage 14.
are drilled, and rotary valves 18 functioning as passage opening/closing valves are inserted into the opening/closing valve insertion holes 17, respectively. This rotary valve 18 is disposed within the branch passage 14 and has a thin plate-like valve body 19 as shown in FIG.
and a valve shaft 20 integrally formed with the valve body 19, and the valve shaft 20 is rotatably supported by a guide sleeve 21 fitted into the opening/closing valve insertion hole 17. The valve stem 20 projects upward from the top surface of the guide sleeve 21, and an arm 22 is fixed to the projecting end.

Referring to FIG. 10, the intake port 6 is connected to a carburetor 25 via a manifold branch 24 of an intake manifold 23. As shown in FIG. On the other hand, the ends of the arms 22 of the rotary valves 18 of each cylinder are connected to each other by a connecting rod 29, and this connecting rod 29 is connected to a control rod 32 fixed to a diaphragm 31 of a negative pressure diaphragm device 30. . The negative pressure diaphragm device 30 has a negative pressure chamber 33 isolated from the atmosphere by a diaphragm 31.
A compression spring 34 for pressing the diaphragm is inserted therein. The negative pressure chamber 33 is connected to a valve chamber 37 of an atmospheric communication control valve 36 via a conduit 35 . The valve chamber 37 is connected to the intake manifold 23 on the one hand via a check valve 38 that allows flow only from the valve chamber 37 into the intake manifold 23, and on the other hand is connected to an atmospheric communication port 39.
It also communicates with the atmosphere via an air filter 40. Further, the atmosphere communication control valve 36 includes a solenoid valve 41, and this solenoid valve 41 includes a valve body 42 for controlling the opening and closing of the atmosphere communication port 39, a movable plunger 43 connected to the valve body 42, and a movable plunger for suction. It is composed of a solenoid 44. Solenoid 44 of electromagnetic valve 41 is connected to an output terminal of electronic control unit 50.

The electronic control unit 50 consists of a digital computer, including a microprocessor (MPU) 51 that performs various calculation processes, a random access memory (RAM) 52, and a read-only memory (ROM) in which control programs, calculation constants, etc. are stored in advance. 53, an input port 54, and an output port 55 are connected to each other via a bidirectional bus 56. Furthermore, a clock generator 57 is provided within the electronic control unit 50 for generating various clock signals. A negative pressure sensor 59 is connected to the input port 54 via an AD converter 58, and a rotation speed sensor 60 is further connected to the input port 54. The negative pressure sensor 59 generates an output voltage proportional to the negative pressure in the intake manifold 23, and this voltage is output to the AD converter 5.
8, the binary number is converted into a corresponding binary number, and this binary number is sent via input port 54 and bus 56.
It is input to MPU51. On the other hand, the rotation speed sensor 6
0 generates a pulse every time the crankshaft rotates by a predetermined crank angle, and this pulse is input to the MPU 51 via the input port 54 and bus 56.

The output port 55 is provided to output data for operating the electromagnetic valve 41, and binary data is written to the output port 55 from the MPU 51 via the bus 56. Output port 5
Each output terminal of the down counter 61 is connected to a corresponding input terminal of the down counter 61. down counter 6
1 is provided to convert the binary data written from the MPU 51 into the corresponding time length, and this down counter 61 counts down the data sent from the output port 55 to the clock generator 57. When the count value reaches 0, the count is completed and a count completion signal is generated at the output terminal. The output terminal of the down counter 61 is an AND gate 62
is connected to one input terminal a of the AND gate 6
The other input terminal b of 2 is connected to the output port 55. On the other hand, the reset input terminal R of the S-R flip-flop 63 is connected to the output terminal of the AND gate 62, and the set input terminal S of the S-R flip-flop 63 is connected to the clock generator 57.
The S-R flip-flop 63 is connected to the clock generator 5.
7 is set at the same time as the down counter 61 starts counting down, and if the input terminal a of the AND gate 62 is at a high level, it is reset by the down counting completion signal when the down counting is completed. Therefore, in this case, S-
The output terminal Q of the R flip-flop 63 is at a high level while down-counting is being performed. On the other hand, when the input terminal b of the AND gate 62 is at a low level, the S-R flip-flop 63 continues to be set, so the output terminal Q of the S-R flip-flop 63 continues to be at a high level. The output terminal Q of the S-R flip-flop 63 is connected to one input terminal a of the AND gate 64.
The other input terminal b of is connected to the output port 55. Furthermore, the output terminal of the AND gate 64 is connected to the solenoid 44 of the solenoid valve 41 via a power amplification circuit 65.
connected to. Therefore, when the input terminal b of the AND gate 64 is at a low level, the solenoid 44 of the solenoid valve 41 is deenergized, and when the input terminal b of the AND gate 62 and the input terminal b of the AND gate 64 are both at a high level, the solenoid 44 of the solenoid valve 41 is deenergized. The solenoid 44 is energized while the down count is being performed. On the other hand, when the input terminal b of the AND gate 62 is at a low level and the input terminal b of the AND gate 64 is at a high level, the solenoid 44 of the electromagnetic valve 41 continues to be energized.

When the solenoid 44 of the electromagnetic valve 41 is energized, the valve body 42 opens the atmosphere communication port 39. As a result, the inside of the negative pressure chamber 33 becomes atmospheric pressure, so the diaphragm 31 is moved downward by the spring force of the compression spring 34, and the rotary valve 18 is thus rotated to fully open the branch passage 14. On the other hand, when the solenoid 44 of the electromagnetic valve 41 is deenergized, the valve body 42 closes the atmosphere communication port 39. At this time, the check valve 38 opens when the negative pressure in the intake manifold 23 becomes larger than the negative pressure in the negative pressure chamber 33 of the negative pressure diaphragm device 30, and the negative pressure in the intake manifold 25 increases to the negative pressure chamber 33.
The valve closes when the pressure becomes smaller than the negative pressure inside the valve body 4.
As long as the valve 2 is closed, the negative pressure in the negative pressure chamber 33 is maintained at the maximum negative pressure generated in the intake manifold 23. When negative pressure is applied within the negative pressure chamber 33, the diaphragm 31 rises against the compression spring 34, and as a result, the rotary valve 18 is rotated and the branch passage 14 is closed. Further, when the input terminals b of both AND gates 62 and 64 are both at a high level, the solenoid 44 of the solenoid valve 41 is activated while the down count is being performed, that is, the output terminal of the S-R flip-flop 63, as described above. It is energized when the voltage appearing at Q is at a high level. Therefore, the time ratio during which the valve body 42 of the solenoid valve 41 opens the atmosphere communication port 39 is proportional to the duty ratio of the pulse applied to the solenoid 44. The longer the time that the valve body 42 opens the atmospheric communication port 39, the lower the negative pressure in the negative pressure chamber 33 of the negative pressure diaphragm device 30, and the larger the opening area of the rotary valve 18 becomes. Therefore, the opening area of the rotary valve 18 is equal to that of the solenoid 44.
It can be seen that the larger the duty ratio of the pulse applied to the pulse is, the larger the duty ratio becomes.

Figure 12 shows the engine speed N (rpm) at which the solenoid valve 41 should be activated and the negative pressure P (-mm) in the intake manifold.
Hg). Note that the area indicated by hatching above the solid line W in FIG.
At R ₀ , the solenoid 44 of the solenoid valve 41 is energized. The solid line W in FIG. 12 indicates a point where the amount of intake air is approximately constant, and therefore it can be seen that the solenoid 44 is energized when the amount of intake air exceeds a predetermined amount. The relationship between the engine speed N (rpm) and the negative pressure P (-mmHg), shown by the solid line W in Fig. 12, is stored in advance in the ROM in the form of a function or data table.
53.

Next, the operation of the flow path control device according to the present invention will be explained with reference to FIG. Referring to FIG. 11, first, in step 70, the engine rotation speed N (rpm) is calculated in the MPU 51 from the output pulse interval of the rotation speed sensor 60, and then in step 71, the negative pressure P (-mm) in the intake manifold is calculated.
The output signal of the negative pressure sensor 59 indicating Hg) is
51. Next, in step 72, it is determined whether the intersection point R between the engine speed N and the negative pressure P is larger than the curve W in FIG. 12, that is, whether it is within the region _R0 . When it is determined in step 72 that the intersection point R between the engine speed N and the negative pressure P is larger than the curve W, the process proceeds to step 73 where a valve closing flag is set, and then in step 74 the solenoid should be energized. A drive signal is written to output port 55. At this time, the input terminal b of the AND gate 62 becomes low level and the input terminal b of the AND gate 64 becomes high level, so that the solenoid 4
4 is energized, and thus the rotary valve 18 fully opens the branch passage 14 as described above. On the other hand, step
At 72, the intersection of engine speed N and negative pressure P is the first
If it is determined that it is not larger than the curve W in FIG. 2, the process proceeds to step 75, where it is determined whether or not the valve closing flag is set. If it is determined in step 75 that the valve-closing flag is not set, the process proceeds to step 76, where drive data for deenergizing the solenoid is written to the output port 55. At this time, the input terminal b of the AND gate 64 becomes low level, so the solenoid 44 is deenergized, and thus the rotary valve 18
completely closes the branch path 14.

On the other hand, if it is determined in step 75 that the valve closing flag is set, that is, in the previous processing cycle, the intersection R between the engine speed N and the negative pressure P was the 12th point.
In the figure, if the intersection point R is within the region _R0 and the intersection point R is smaller than the solid line W in FIG. 12 in the current processing cycle, the process advances to step 77. In step 77, a constant value A is subtracted from the pulse width K to be applied to the solenoid 44, and the result of this subtraction is used as the pulse width K.
shall be. Next, in step 78, it is determined whether the pulse width K is smaller than the constant value B, and if the pulse width K is not smaller than the constant value B, the process proceeds to step 79, where the solenoid drive data is written to the output port 55. be included. At this time, both AND gate 6
Both input terminals b of 2 and 64 become high level, and the down counter 61 is activated for a time corresponding to the pulse width K.
A down counter action is performed. step 77
The pulse width K is subtracted by a constant value A every time the pulse width K is passed through the solenoid 44.
becomes gradually narrower as shown in FIG. Therefore, as described above, since the negative pressure in the negative pressure chamber 33 gradually increases, the rotary valve 18 gradually closes the branch passage 14. On the other hand, if it is determined in step 78 that the pulse width K is smaller than the constant value B, the process proceeds to step 80, where the pulse width K is set to the initial value _K0 . After the valve closing flag is lowered in step 81, the process proceeds to step 76, where drive data for deenergizing the solenoid is written to the output port 55.

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. 4, a strong swirling flow is generated. 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. Upper wall surface 13 of spiral part B
Since the flow path is deflected downward by the steeply inclined wall D of the volute end C, the air mixture flow traveling along the vortex end C, that is, the outlet opening 16 of the branch passage 14
A large negative pressure is generated. Therefore, the entrance passage section A
Since the pressure difference between the vortex end portion C and the vortex end portion C is large, when the rotary valve 18 opens, a large amount of air-fuel mixture is sent into the vortex portion B via the branch passage 14. As described above, when the rotary valve 18 opens during engine high-speed and high-load operation, not only does the overall flow path area increase, but also a large amount of intake air flows into the volute B through the branch path 14 with low resistance. High filling efficiency can be ensured. In addition, by providing the inclined surface 9a in the inlet passage A, a portion of the air-fuel mixture fed into the inlet passage A is given a downward force, and as a result, this air-fuel mixture flows through the inlet passage without swirling. Since the fluid flows into the spiral portion B along the lower wall surface of A, the inflow resistance becomes small, thus making it possible to further improve the filling efficiency during high-speed, high-load operation. Further, since the rotary valve is gradually closed when the amount of intake air decreases, sudden changes in torque can be prevented.

As described above, according to the present invention, when the amount of intake air is reduced, the on-off valve is gradually closed, making it possible to prevent sudden changes in torque, thus ensuring good drivability. can do. On the other hand, when the amount of intake air is suddenly increased, the on-off valve opens immediately, making it possible to obtain good acceleration. In the present invention, the amount of intake air is determined from the intake manifold negative pressure and the engine speed, but the amount of intake air can be measured using an air flow meter.

[Brief explanation of drawings]

Fig. 1 is a plan view of an internal combustion engine according to the present invention, Fig. 2 is a plan view of an internal combustion engine according to the present invention;
The figure is a cross-sectional view taken along the - line in Figure 1.
The figure is a perspective view showing the shape of a helical intake port.
Fig. 4 is a plan view of Fig. 3, Fig. 5 is a side sectional view taken along the branch road in Fig. 3, Fig. 6 is a sectional view taken along the - line in Fig. 4, and Fig. 7. is a sectional view taken along the - line in Fig. 4, Fig. 8 is a sectional view taken along the - line in Fig. 4, Fig. 9 is a perspective view of the rotary valve, and Fig. 10 is a sectional view of the flow path control device. An overall view, FIG. 11 is a flowchart for explaining the operation of the flow path control device, FIG. 12 is a diagram showing the valve opening area of the rotary valve, and FIG. 13 is a diagram showing the pulses applied to the solenoid. be. 5... Intake valve, 6... Helical intake port,
14... Branch road, 18... Rotary, 30...
Negative pressure diaphragm device, 41... solenoid valve.

Claims (1)

[Claims] 1. In a helical intake port constituted by a spiral portion formed around the intake valve and an inlet passage portion that is connected tangentially to the spiral portion and extends almost straight, the intake port is branched from the inlet passage portion and the above-mentioned A branch passage communicating with the spiral terminal end of the spiral part is formed in the cylinder head, and an on-off valve is provided in the branch passage, and the on-off valve is connected to an actuator that responds to the amount of intake air so that the amount of intake air reaches the above-mentioned level. A helical type valve that gradually closes the on-off valve to a fully closed position when the intake air amount falls below a certain amount, and immediately opens the on-off valve to a fully open position when the intake air amount exceeds the predetermined amount. Intake port flow path control device.