JPH0261611B2 - - 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, in this flow path control device, the on-off valve is opened when the amount of intake air exceeds a predetermined amount, regardless of the engine temperature. However, when the engine temperature is low, it is necessary to promote fuel atomization and improve combustion efficiency by increasing swirling flow rather than charging efficiency, but the above-mentioned flow path control device does not take this into consideration. Not yet.

The present invention provides a helical intake port flow path control device that controls the opening operation of an on-off valve provided in a branch passage in accordance with the engine temperature and improves combustion efficiency when the engine temperature is low. There is a particular thing.

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.

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 constituting the on-off valves are inserted into the on-off valve insertion holes 17, respectively. The rotary valve 18 is disposed within the branch passage 14 and includes a thin plate-shaped valve body 19 as shown in FIG. 9, and a valve stem 20 integrally formed with the valve body 19. It is rotatably supported by a guide sleeve 21 fitted into the on-off 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 rotary valve 1 of each cylinder
The eight arms 22 are connected to each other by a connecting rod 30, which is connected to a control rod 33 fixed to a diaphragm 32 of a vacuum diaphragm device 31. This negative pressure diaphragm device 31 includes a negative pressure chamber 34 isolated from the atmosphere by a diaphragm 32, and a compression spring 35 for pressing the diaphragm is inserted into this negative pressure chamber 34.
The negative pressure chamber 34 communicates with the atmosphere via a throttle 36 on the one hand and is connected to a negative pressure control valve 37 on the other hand. The negative pressure control valve 37 includes a negative pressure control chamber 39 isolated from the atmosphere by a diaphragm 38, and a first valve chamber 41 and a second valve chamber 42 separated by a partition wall 40. A compression spring 43 for pressing the diaphragm is inserted. On the other hand, the first valve chamber 41
A valve body 45 that controls the opening and closing of a valve port 44 formed on the partition wall 40 is inserted into the interior.
is connected to diaphragm 38 via valve rod 46. The second valve chamber 42 is connected to the negative pressure chamber 34,
The first negative pressure chamber 41 is connected into the intake manifold 48 via a negative pressure conduit 47 . Furthermore, negative pressure control room 3
9 on the one hand, a throttle 49 and negative pressure conduits 56, 47;
is connected to the intake manifold 48 via a throttle 51, an atmospheric conduit 52 and a temperature-sensitive shut-off valve 5.
3 to the atmosphere. This temperature-sensitive shutoff valve 53
For example, in response to the engine cooling water temperature, when the engine cooling water temperature is lower than a predetermined constant temperature, the atmospheric conduit 52 is shut off, and when the engine cooling water temperature is higher than the above-mentioned constant temperature, the atmospheric conduit 52 is communicated with the atmosphere. urge The temperature-sensitive shutoff valve 53 can be activated in response to the wall temperature of the engine body, the engine lubricating oil temperature, or the like.

When the engine cooling water temperature is low, the temperature-sensitive shutoff valve 53 shuts off the atmospheric conduit 52 as described above. Therefore, at this time, a negative pressure equal to the negative pressure generated in the intake manifold 48 is generated in the negative pressure control chamber 39 of the negative pressure control valve 37. When the negative pressure in the negative pressure control chamber 39 becomes larger than the first set value determined by the spring force of the compression spring 43, the diaphragm 38
3 so that the valve body 45 rises against the valve port 4.
4, so that the negative pressure diaphragm device 31
Negative pressure is generated within the negative pressure chamber 34 of. Negative pressure chamber 34
When a negative pressure is generated within, the diaphragm 32 rises against the compression spring 35, so that the rotary valve 18 closes the branch passage 14. On the other hand, when the negative pressure in the negative pressure control chamber 39 becomes smaller than the above-mentioned first set value, the diaphragm 38 is lowered by the spring force of the compression spring 43, so that the valve body 45 closes the valve port 44. At this time, the atmosphere is introduced into the negative pressure chamber 34 of the negative pressure diaphragm device 31 through the throttle 36, so that the inside of the negative pressure chamber 34 becomes atmospheric pressure. As a result, the diaphragm 32 is lowered by the spring force of the compression spring 35, and the rotary valve 18 fully opens the branch passage 14.

The solid line A in FIG. 11 indicates the first setting value, and the solid line A
The rotary valve 18 fully opens the branch passage 14 in the hatched area above the . In Figure 11, the vertical axis is torque T, and the horizontal axis is engine speed N (r・p・m).
The solid line A indicates a point where the negative pressure within the intake manifold 48, that is, the negative pressure in the intake pipe is approximately constant.

On the other hand, when the engine cooling water temperature rises, the temperature-sensitive shutoff valve 5
3 allows the atmospheric conduit 52 to communicate with the atmosphere, so that atmospheric air is bled into the negative pressure control chamber 39 of the negative pressure control valve 37 via the restrictor 51. As a result, the negative pressure in the intake manifold 48 that is applied to the negative pressure control chamber 39 is reduced by this bleed air, and thus the negative pressure in the intake manifold 48 when the valve body 45 opens the valve port 44 is reduced to the level described above. The second setting value is larger than the first setting value. This second set value
The rotary valve 18 fully opens the branch passage 14 in the hatched area shown by the solid line B in FIG. 1 above the solid line B. It can be seen that the intake pipe negative pressure when the rotary valve 18 is opened is smaller when the engine temperature is low than when the engine temperature is high.

As described above, the rotary valve 18 shuts off the branch passage 14 when the engine is operated at low load with a large negative pressure in the intake pipe. 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 under high load with a small negative pressure in the intake pipe, the rotary valve 18 opens, so that part of the air-fuel mixture sent into the inlet passage A flows through the branch passage 14 with small flow resistance to the spiral part B.
sent inside. This air-fuel mixture flows from the inlet passage A into the volute B and collides head-on with the air-fuel mixture flowing along the upper wall surface 13 of the vortex B, resulting in a mixture flow flowing along the upper wall surface 13 of the vortex B. is decelerated and the swirling flow is weakened. In this way, when the engine is operated at high speed and high load, the rotary valve 18 opens, which not only increases the overall flow path area but also weakens the swirling flow, thereby ensuring a high filling effect. In addition, the entrance passage section A
By providing the inclined surface 9a on the inlet passage section A
A part of the air-fuel mixture sent into the air-fuel mixture is given a downward force, and as a result, this air-fuel mixture flows into the spiral part B along the lower wall surface of the inlet passage part A without swirling, so that the inflow resistance is small. In this way, the filling efficiency during high-speed, high-load operation can be further improved.

According to the present invention, as can be seen from the solid line A in FIG. 11, when the engine temperature is low, the rotary valve 18 continues to be closed until the engine load is considerably large.
A strong swirling flow is thereby generated within the combustion chamber. When the engine temperature is low, fuel atomization is insufficient and combustion deteriorates, but by generating a strong swirling flow in the combustion chamber even in areas where the engine load is quite large, fuel atomization becomes good. In this way, combustion efficiency can be improved. Furthermore, by generating a strong swirling flow in the combustion chamber even in regions where the engine load is considerably large, the load region in which sufficiently stable combustion can be ensured using a lean mixture is expanded, and the engine load range becomes wider and the engine load becomes more stable. Since the machine fuel increase can be set so that the air-fuel mixture becomes lean, the fuel consumption rate can be improved.

[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, and Figure 3.
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 of Fig. 4, and Fig. 7. is a cross-sectional view taken along line - in Fig. 4, Fig. 8 is a cross-sectional view taken along line - in Fig. 4, Fig. 9 is a perspective view of the rotary valve, and Fig. 10 is a cross-sectional view of the flow path control device. Overall view,
FIG. 11 is a diagram showing the relationship between torque and engine speed. 5...Intake valve, 6...Helical intake port, 14
... Branch path, 18 ... Rotary valve, 37 ... Negative pressure control valve, 53 ... Temperature-sensitive cutoff 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 connected tangentially to the spiral portion and extending almost straight, the above-mentioned helical intake port is branched from the inlet passage portion. A branch passage communicating with the spiral terminal end of the spiral portion is formed in the cylinder head, and a normally closed opening/closing valve that responds to engine temperature and intake pipe negative pressure is provided in the branch passage, so that the intake pipe negative pressure is predetermined. When the engine temperature becomes smaller than a predetermined set value, the opening/closing valve is opened, and the set value is changed according to the engine temperature, and when the engine temperature is lower than a predetermined temperature, the above set value is changed to the first set value. A flow path control device for a helical intake port, wherein the set value is set to a set value, and when the engine temperature is higher than the predetermined temperature, the set value is set to a second set value having a negative pressure larger than the first set value. .