JPS6135367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an intake system for a four-stroke internal combustion engine.

A conventional device of this type is schematically shown in FIG. In the figure, 01 is a piston, 02 is a combustion chamber of a cylinder, and 03 is an exhaust valve, which is controlled to open and close by an exhaust cam (not shown). 04 is the exhaust passage, 05 is the turbine of the exhaust turbo supercharger, through which the exhaust gas is guided, and 0
Reference numeral 6 denotes a blower of an exhaust turbo supercharger, which is arranged on the same axis as the turbine 05. 07 is a throttle valve, 08 is an intake passage, and 09 is an intake valve, whose opening and closing are controlled by an intake cam (not shown).In the exhaust stroke of the piston 01, exhaust gas flows from the combustion chamber 02 through the exhaust valve 03 and into the exhaust passage 04. After that, it is guided to turbine 05. At this time, the turbine 05 is rotationally driven by the energy of the exhaust gas, and this output causes the blower 06 to forcefully send air from the atmosphere through the throttle valve 07 and into the intake passage.
Sent to 8.

During the intake stroke of the piston 01, the compressed air is drawn into the combustion chamber 02 through the intake valve 09.

In an engine such as a gasoline engine whose load is adjusted by a throttle valve 07, the throttle valve 07 is throttled during partial load and idling, and the load is adjusted by lowering the pressure in the intake passage 08 and reducing the amount of intake air.

However, the conventional method described above has the following drawbacks.

Figure 2 shows the conventional intake valve 09 and exhaust valve 0.
The opening area of No. 3 is shown with the crank angle as the horizontal axis.
In the figure, BDC indicates bottom dead center and TDC indicates top dead center.

1 In conventional engines, the intake valve opening timing is set to 3rd.
By proceeding as shown in the figure and increasing the overlap of the intake and exhaust valves, it is possible to increase the output torque at full load in the medium and low speed range of the engine. That is, 〓〓〓〓
(a) Figure 4 shows how the cylinder pressure (solid line), exhaust pressure (dashed line), and intake pressure (dotted chain line) change during the intake and exhaust stroke at full load in the medium and low speed range, with the crank angle as the horizontal axis. However, lower A in the figure is for the intake valve opening timing in Figure 2,
B above shows the case of the intake valve opening timing shown in FIG.

b At full load in the medium and low speed range, the throttle of the turbine 05 of the exhaust turbocharger is relatively open compared to the high speed range, and the operating efficiency of the exhaust turbocharger is also good, so the pressure level is lower than that of the exhaust pressure. The pressure level of the intake pressure is high. For this reason, the fourth
As shown in the figure, the exhaust stroke (BDC to TDC
In the latter half of the period shown in Figure 3), the in-cylinder pressure is lower than the intake pressure, and by advancing the timing of the intake valve opening and increasing the overlap, as shown in the cam in Figure 3 of B, the period shown in the shaded area shown in B is It can create an atrium.

(c) In FIG. 5, changes in the gas flow rate passing through the intake and exhaust valves in the case of the cams shown in FIGS. 2 and 3 are shown as A and B, respectively. B compared to A
A blowout shown by the shaded area is created near TDC, which cleans the residual exhaust gas accumulated in the combustion chamber, increasing the intake efficiency and increasing the engine's output torque by the increased amount of intake air. be able to.

2. However, the cam with large overlap shown in FIG. 3 causes a decrease in output and deterioration of combustion performance at high speeds, as well as deterioration of combustion performance at partial load and idling. That is, (a) Figure 6 shows how the cylinder pressure, exhaust pressure, and intake pressure change when the engine is running at high speed, in the same way as Figure 4, and A indicates the intake valve opening timing in Figure 2. In the case of , B shows the case of the intake valve opening/closing timing with a large overlap as shown in FIG.

(b) At high speed, the exhaust turbocharger turbine 0
5 is relatively throttled compared to low speed, the pressure level of the exhaust pressure is higher than the pressure level of the intake pressure. Therefore, at B where the overlap is large, the in-cylinder pressure during the overlap period is lower than the intake pressure, as shown in the shaded area. The exhaust gas inside the cylinder blows back into the intake passage.

(c) In FIG. 7, changes in the flow rate of gas passing through the intake and exhaust valves are shown in A and B, respectively, for the intake valve opening timings shown in FIGS. 2 and 3 at this time. Compared to A, B blows back near TDC as shown by the shaded area, and this causes exhaust to flow into the intake passage 08, reducing the amount of intake air and increasing the amount of residual exhaust. This results in a decrease in output torque at high speeds and deterioration in combustion performance.

(d) When the engine is under partial load or idling,
In an engine whose load is adjusted by the throttle valve 07, the intake passage 08 is controlled by the throttle valve 07.
As the internal pressure decreases and becomes lower than the exhaust pressure, the third
For cams with large overlap as shown in the figure, B
Blowback occurs, increasing the amount of residual exhaust gas and deteriorating combustion performance.

3. Therefore, in the conventional engine, as shown in FIG. 3, it is not possible to advance the opening timing of the intake valve and increase the overlap to increase the output torque at full load in the medium and low speed range.

4 In addition, in conventional engines, the closing timing of the intake valve is advanced as shown in Figure 8, and the intake valve is closed as soon as possible after the bottom dead center of the intake stroke.
It is possible to increase the output torque at full load in the medium and low speed range of the engine. In other words, (a) As shown in Figure 5B, in the medium and low speed range, the air sucked into the cylinder is returned to the intake passage after the bottom dead center (BDC) of the intake stroke until the intake valve closes. This causes the intake air to be pushed back. Therefore, by closing the intake valve earlier as shown by the dotted line in Figure 5B, a larger amount of air can be filled into the cylinder and the output torque of the engine can be increased. can.

5. However, as shown in FIG. 8, with the cam that advances the intake valve closing timing, the output is reduced in the high speed range of the engine. In other words, (a) As shown in Figure 7B, in the high-speed range, the piston descends quickly during the intake stroke and reaches the bottom dead center.
Sufficient intake air has not yet been filled near BDC, and by advancing the closing timing of the intake valve as shown by the dotted line, an insufficient amount of intake air is filled near BDC as shown by the diagonal line.
This results in a decrease in engine output.

〓〓〓〓
6. Therefore, in the conventional engine, as shown in FIG. 8, it is not possible to advance the intake valve closing timing to increase the output torque at full load in the medium and low speed range.

An object of the present invention is to provide a 4-cycle internal combustion engine with a high speed engine that can operate at full load in the medium and low speed range without causing a decrease in output in the high speed range, deterioration of combustion performance, or deterioration of combustion performance at partial load and idling. The object of the present invention is to provide an intake device that can increase output torque, and its features are as follows.

In a four-stroke internal combustion engine, an auxiliary intake passage and an auxiliary intake valve are provided branching off from the intake passage, and a check valve that only allows intake air to flow into the cylinder is provided within the auxiliary intake passage. Furthermore, the opening/closing timing of the auxiliary intake valve is made to be different from the opening/closing timing of the above-mentioned intake valves. This creates a blow-through, and its cleaning effect increases suction efficiency and increases the engine's output torque.At the same time, when the engine is at high speed, under partial load, or when idling, the check valve prevents the exhaust from blowing back from the auxiliary intake valve. (2) The closing timing of the auxiliary intake valve is set to the same timing as the intake valve closing timing of a conventional engine.
In addition, by advancing the intake valve closing timing from the intake valve closing timing of conventional engines, in the medium and low speed range of the engine, the check valve can push back the intake air after the bottom dead center BDC of the piston intake stroke. By increasing the intake air filling amount and increasing the engine's output torque, and by replenishing the intake air after bottom dead center through the auxiliary intake valve in the engine's high-speed range, This is to prevent a drop in output.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 9 is an explanatory diagram showing the main parts of an engine provided with the intake system of the first embodiment according to the present invention, and FIG.
FIG. 3 is an explanatory diagram showing an intake cam and a tappet roller of the device shown in the figure.

In the figure, 1 is a piston, 2 is a combustion chamber of a cylinder, and 3 is an exhaust valve, which is controlled to open and close by an exhaust cam (not shown). 4 is an exhaust passage, 5 is a turbine of an exhaust turbo supercharger, through which exhaust gas is guided, and 6 is a blower of the exhaust turbo supercharger, which is disposed on the same axis as the turbine 5. 7 is a throttle valve, 8 is an intake passage, and 9 is an intake valve, which are controlled to open and close by an intake cam 13 via an intake valve tappet roller 14 by a rocker arm (not shown).

Reference numeral 10 denotes an auxiliary intake valve whose opening and closing are controlled by an auxiliary intake valve rocker arm (not shown) by an intake cam 13 via an auxiliary intake valve tappet roller 15. Further, the auxiliary intake valve tappet roller 15 is arranged at a position advanced relative to the intake valve tappet roller 14 by an angle θ relative to the rotation of the intake cam 13, as shown in FIG. In this embodiment, the intake cam 13 is connected to the intake valve 9 and the auxiliary intake valve 1.
Although the auxiliary intake valve cam is commonly used for the opening/closing control of the auxiliary intake valve 10, a new auxiliary intake valve cam may be newly provided exclusively for the opening/closing control of the auxiliary intake valve 10.

Reference numeral 11 denotes an auxiliary intake passage, which is branched from the intake passage 8 and led to the auxiliary intake valve 10 section.

Reference numeral 12 denotes a check valve, which is disposed within the auxiliary intake passage 11 and has a structure such as, for example, a reed valve that only allows intake air to flow into the combustion chamber of the cylinder.

The operation in the case of the above configuration will be described.

FIG. 11 shows the opening areas of the exhaust valve 3, intake valve 9, and auxiliary intake valve 10 in this embodiment with respect to the crank angle.

The opening timing of the auxiliary intake valve 10 is advanced by 2θ in terms of crank angle than the opening timing of the intake valve 9.

The effects obtained in this embodiment that are different from the conventional ones are as follows.

1 When the engine is under full load in the medium-low speed range, the exhaust pressure is lower than the intake pressure in the latter half of the exhaust stroke, as shown in Figure 4, so the auxiliary intake valve 10 shown with diagonal lines in Figure 11 is closed. Due to the overlap caused by this, a blow-through of the intake air as shown in Fig. 5B is obtained, and the exhaust gas remaining in the combustion chamber 2 is cleaned out.
This increases suction efficiency and increases the amount of intake air to be filled.

2. When the engine is at high speed, under partial load, or idling, the exhaust pressure in the latter half of the exhaust stroke is higher than the intake pressure, as shown in Figure 6, but the check valve 12 installed in the auxiliary intake passage 11 As a result, blowback of exhaust gas is prevented, and the intake air amount does not decrease or the residual exhaust gas increases, which would occur if the overlap was increased in a conventional engine.

The present embodiment as described above has the following effects.

(1) When the engine is under full load in the medium and low speed range, the output torque can be increased by increasing the amount of intake air.

(2) In addition, this is accompanied by a decrease in output due to a decrease in air volume and an increase in residual exhaust gas at high speeds, and a deterioration in combustion performance due to an increase in residual exhaust gas during partial load and idling. Never.

A second embodiment of the present invention will be described.

In the same structure as the first embodiment shown in FIG. 9, the opening and closing of the auxiliary intake valve 10 is controlled by an auxiliary intake valve cam (not shown), and the valve closing timing is set to the intake valve closing timing of the conventional engine. The closing timing of the intake valve 9 is set to be approximately the same timing as the timing shown in FIG.

The operation in the case of the above configuration will be described.

FIG. 12 shows the opening areas of the exhaust valve 3, intake valve 9, and auxiliary intake valve 10 in accordance with this embodiment with respect to the crank angle.

The effects obtained in this embodiment that are different from the conventional ones are as follows.

(1) In the medium and low speed range of the engine, the closing timing of the intake valve 9 is advanced compared to the conventional engine, and the auxiliary intake valve 10 is closed at the bottom dead center as shown by the diagonal line in Figure 12.
Although it remains open after BDC, since the check valve prevents the intake air from flowing backward, the intake air is not pushed back as shown by the diagonal line after the bottom dead center of the intake stroke in Figure 5B, and the intake air is filled to that extent. The amount increases.

(2) In the high-speed range of the engine, the intake valve closes earlier than the bottom dead center of the intake stroke, but because the auxiliary intake valve is open, there is insufficient intake air filling as seen in the latter half of the intake stroke in Figure 7B. This does not occur, and since intake air is replenished through the auxiliary intake valve 10 even after bottom dead center, the amount of filled air does not decrease.

The above embodiment has the following effects.

(1) In the medium and low speed range of the engine, an increase in the output torque can be obtained by increasing the amount of intake air.

(2) Furthermore, since there is no reduction in the amount of intake air in the high-speed range, there is no reduction in output in the high-speed range.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the intake system of a conventional four-stroke internal combustion engine, Figure 2 is a diagram showing the opening areas of the exhaust valve and intake valve of the engine in Figure 1, and Figure 3 is the engine in Figure 1. Figure 4 is a diagram showing the opening areas of the exhaust valve and intake valve when the intake valve opening timing is advanced. Figure 5 is a diagram showing the flow rate of gas passing through the intake and exhaust valve section in the case of Figure 4. Figure 6 is a diagram showing the cylinder pressure, exhaust pressure, and intake pressure during the intake and exhaust stroke of the engine at high speed. A diagram showing the changes in the middle, Figure 7 is the 6th
Figure 8 is a diagram showing the flow rate of gas passing through the intake/exhaust valve section in the case shown in Fig. 8, Figure 8 is a diagram showing the valve opening area when the opening/closing timing of the intake valve is advanced, and Figure 9 is a diagram showing the first embodiment according to the present invention. FIG. 10 is an explanatory diagram showing the intake cam and tappet roller of the engine shown in FIG. 9, and FIG.
FIG. 12 is a diagram showing the opening areas of the exhaust valve, intake valve, and auxiliary intake valve of the engine shown in FIG. FIG. 3 is a diagram showing the opening area. 1...Piston, 2...Combustion chamber, 3...Exhaust valve, 4...
Exhaust passage, 5... Turbine of exhaust turbo supercharger, 6
...Exhaust turbo supercharger blower, 8...Intake passage, 9
...Intake valve, 10...Auxiliary intake valve, 11...Auxiliary intake passage, 12...Check valve. 〓〓〓〓

Claims (1)

[Claims] 1. An intake valve that opens and closes the intake passage that opens to the cylinder, an exhaust valve that opens and closes the exhaust passage that opens to the cylinder, and a turbine that outputs output by introducing exhaust gas and is driven by the same turbine to forcefully send air to the intake passage. In a four-stroke internal combustion engine having an exhaust turbocharger consisting of a blower, an auxiliary intake passage branching from the intake passage and opening into the cylinder, the opening timing of which is advanced from the opening timing of the intake valve, and the opening timing of the intake valve is the same. The present invention is characterized by comprising an auxiliary intake valve that opens and closes the auxiliary intake passage at an opening and closing timing different from the opening and closing timing of the intake valve, and a check valve that is provided in the auxiliary intake passage and allows only intake air to flow into the cylinder. Intake system for 4-stroke internal combustion engine.