JPH057537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an intake system for an internal combustion engine that is equipped with a turbocharger and has two intake ports in its combustion chamber.

<Background Art> An example of a conventional intake system for an internal combustion engine equipped with a turbocharger is the one shown in Japanese Patent Publication No. 58-23489.

However, in this type of conventional device, when the boost pressure rises excessively, a relief valve installed in the intake passage downstream of the compressor opens and releases the intake air to the atmosphere, or the intake air is returned to the intake passage upstream of the compressor. This has caused the following problems:

In other words, when excess intake air is released to the atmosphere, fuel is supplied from the injection valve according to the intake air flow rate detected by the air flow meter installed upstream of the compressor, so the amount of intake air actually supplied to the combustion chamber is If more fuel than the corresponding amount is supplied, a rich mixture is formed, fuel is wasted, and combustibility deteriorates.

Furthermore, when excess intake air is returned to the intake passage upstream of the compressor, problems such as the expansion of the supercharged intake air generate noise and pulsating supercharging pressure, causing the air flow meter to malfunction.

<Purpose of the Invention> The present invention was devised in view of these conventional problems, and improves output, fuel efficiency, and exhaust emissions by obtaining good intake characteristics using inertia supercharging over the entire speed range of the engine. Equipped with a turbocharger that improves the composition and suppresses excessive rise in boost pressure without affecting the mixture concentration or causing noise, ensuring stable drivability. The purpose of the present invention is to provide an intake device for an internal combustion engine.

<Summary of the Invention> Therefore, the present invention provides an internal combustion engine with a turbocharger, which includes: a supercharging pressure detection means for detecting the pressure of the supercharged intake air by the compressor; two intake ports opening into the combustion chamber; Two high-speed intake passages each connected to the two intake ports, two on-off valves installed to simultaneously open and close each high-speed intake passage, and one interposed in one high-speed intake passage. The two on-off valves are closed in the low-speed rotation range of the engine, and are connected to the low-speed intake passage bypassing the on-off valves and having a smaller passage cross-sectional area and larger passage length than the high-speed intake passage. In this case, an on-off valve control means is provided which opens the valve and closes it unconditionally when the supercharging pressure detected by the supercharging pressure detecting means is equal to or higher than a set value.

As a result, in the low-speed rotation range of the engine, only the low-speed intake passage is opened and intake air is supplied from one intake port, and inertia supercharging that matches the low-speed rotation range is performed, and a strong swirl is generated. , While supercharging by the compressor becomes effective in the high-speed rotation range, the two high-speed intake passages are simultaneously opened to perform inertia turbocharging that matches the high-speed rotation range, and the intake passage resistance increases due to the increase in passage cross-sectional area. The maximum output can be increased as much as possible by reducing .

In addition, when the boost pressure of the compressor becomes excessive, the on-off valve closes and air is taken in from the low-speed intake passage, causing the boost pressure to rise, which can adversely affect the mixture concentration and generate noise. Since it can be suppressed smoothly without any problems, stable drivability can be obtained.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

In FIGS. 1 and 2 showing the first embodiment, a cylinder head 2 of an engine 1 is formed with two intake ports 4A and 4B that open into a combustion chamber 3. Two high-speed intake passages 6A and 6B branch from the collector 5 upstream, respectively.
are independently connected.

The passage cross-sectional area S and passage length L of these high-speed intake passages 6A and 6B are selected so that good inertial supercharging is performed in the high-speed rotation range of the engine, for example, 5000 to 6000 rpm, and maximum output is obtained. Ru.

On-off valves 7A and 7B are interposed at the downstream ends of the two high-speed intake passages 6A and 6B, respectively.
The two on-off valves 7A and 7B are connected to a common rotating shaft 8, and are opened and closed simultaneously by an actuator to be described later. The end of the rotating shaft 8 is connected to the output rod 10 of the actuator 10 via a lever 9.
Connect to a. A pressure working chamber 10d having a return spring 10c installed on one side is defined by a diaphragm 10b connected to an output rod 10a.The pressure working chamber 10d is connected to an output port 11a of a solenoid valve 11. The solenoid valve 11 communicates with the atmosphere through a negative pressure port 11b that communicates via a communication pipe 15 with a negative pressure tank 14 in which intake negative pressure downstream of the throttle valve 12 of the collector 5 is introduced and stored through a check valve 13. Switching is controlled by the output from the control circuit 16 so that the atmospheric port 11c is selectively communicated with the output port 11a by the valve body 11d. The control circuit 16 operates using a battery 17 as a power source as described later.

In addition, the collector 5 and the on-off valve 7A are bypassed by the on-off valve 7A interposed in one of the high-speed intake passages 6A.
Low-speed intake passage 1 connecting to the downstream high-speed intake passage 6A
8 is provided.

The low-speed intake passage 18 has a passage cross-sectional area S′ smaller than that of the high-speed intake passages 6A and 6B, and a passage length so that good inertial supercharging is performed in the low-speed rotation range of the engine, for example, 2000 to 3000 rpm. L′ is chosen to be large.

A fuel injection valve 19 is provided downstream of the on-off valve 7A of the high-speed intake passage 6A on the side where the low-speed intake passage 18 is merged and connected, and is configured to supply fuel to the air supplied from these intake passages 6A and 18. It's getting old. Further, the other high-speed intake passage 6B is not provided with a fuel injection valve, and no fuel is supplied thereto.

The high-speed intake passage 6A and the low-speed intake passage 18, and the low-speed intake passage 18 and the fuel injection valve 19 intersect with each other at acute angles, so that fuel is supplied without reducing the intake flow velocity and a mixture with a uniform concentration is obtained. generate.

Further, 20 is an exhaust gas recirculation valve that controls the amount of exhaust gas recirculated from the exhaust path 24 into the collector 5 .

On the other hand, a compressor 23A of a turbocharger 23 is installed in the intake passage 22 upstream of the collector 5.
By rotating the turbine 23B installed in the exhaust passage 24 with the exhaust pressure, the compressor 23A coaxial with the turbine 23B is rotated to forcefully send (supercharge) intake air to the engine 1. An exhaust bypass valve 26 is interposed in the exhaust bypass passage 25 that bypasses the turbine 23A, and the compressor 23A and the throttle valve 1
The opening and closing of the exhaust bypass valve 26 is controlled by a diaphragm actuator 27 that operates according to the supercharging pressure in the intake passage 22 between the two. This results in
The amount of exhaust gas bypassed to the exhaust bypass passage 25 without rotating the turbine 23B is controlled according to the supercharging pressure, thereby suppressing an increase in the supercharging pressure.

Further, a supercharging pressure sensor 28 as supercharging pressure detection means is provided in the intake passage 22 between the compressor 23A and the throttle valve 12, and a supercharging pressure signal detected by the sensor is input to the control circuit 16.

In addition to the boost pressure P signal, the control circuit 16 also receives engine intake air flow rate Q, rotational speed N, and throttle valve opening θ.
etc., and an injection pulse having a pulse width set according to the engine operating state detected based on these signals is input to the fuel injection valve 19. In addition, in the engine low speed range, the output to the solenoid valve 11 is turned on, and the valve body 11d is attracted by electromagnetic force, and the output port 1
1a and the atmospheric port 11c are communicated, the output to the solenoid valve 11 is turned OFF in the high speed rotation range, and the output port 11a and the negative pressure port 11b are communicated, but the boost pressure is the opening pressure of the exhaust bypass valve 26. When the upper set value (e.g. 400mmHg) is exceeded, the output to the solenoid valve 11 is unconditionally turned ON.
Once the boost pressure reaches the upper set value, keep the solenoid valve 11 in the ON state until it drops to a lower set value (for example, 300 mmHg) to keep the output port 11a and the atmospheric port 11c in communication. Control.

Note that 29 is an air flow meter and 30 is an air cleaner.

Next, the action will be explained.

In a low-speed rotation range where the engine rotation speed, fuel injection pulse width, or throttle valve opening is below the set value, the control circuit 16
The output to the solenoid valve 11 is turned ON, and the pressure operating chamber 10d of the actuator 10 is connected to the atmospheric port 11.
It is opened to the atmosphere through c. As a result, the output rod 10 is
a is in the extended position, lever 9, rotation shaft 8
The two on-off valves 7A and 7B are maintained in a fully closed state via the.

In this state, the intake air passes through the throttle valve 12 and is then supplied into the combustion chamber 3 from one intake port 4A. The fuel injected from the combustion injection valve 19 on the downstream side of the on-off valve 7A is mixed with this intake to form an air-fuel mixture, and this air-fuel mixture is combusted in the combustion chamber 3.

In such a low-speed rotation range, the compressor 23A supercharging is not effective, but the high-speed intake passage 6A,
Since the intake air is supplied through the low-speed intake passage 18, which has a smaller passage cross-sectional area and a longer passage length than the 6B, a good inertial supercharging effect that matches the low-speed rotation range is obtained, and the intake volumetric efficiency is improved. High output can be obtained. Furthermore, as described above, the low-speed intake passage 18 intersects the high-speed intake passage 6A at an acute angle, and the intake air flows into the combustion chamber 3 through only one intake port 4A. As a result, a strong swirl is generated and the combustibility improvement effect is enhanced, resulting in a significant improvement in fuel efficiency and exhaust composition.

Note that since the downstream end of the low-speed intake passage 18 opens into the high-speed intake passage 6A near the on-off valve 7A, there is little dead space when the on-off valve 7A is closed, and sufficiently efficient inertial supercharging can be obtained.

On the other hand, in a high-speed rotation range where the engine rotation speed, fuel injection pulse width, throttle valve opening, etc. are higher than the set value, the output from the control circuit 16 to the solenoid valve 11 is turned OFF.
Switching control is performed so that ports 11a and 11b of solenoid valve 11 communicate with each other. As a result, the negative pressure accumulated in the negative pressure tank 14 is introduced into the pressure working chamber 10d, the diaphragm 10b moves to the left in the figure against the return spring 10c, and the output rod 10a connected to it is pulled in. It will be done. Therefore, the rotating shaft 8 rotates around the shaft via the lever 9, and the two on-off valves 7A and 7B are switched from closed to open.

In this state, the intake air that has passed through the throttle valve 12 is supplied into the combustion chamber 3 from the two intake ports 4A, 4B mainly via the two open high-speed intake passages 6A, 6B.

In this way, while supercharging by the turbo supercharger becomes effective in the high-speed rotation range, intake air is supplied through the two high-speed intake passages 6A and 6B, which have a large passage cross-sectional area and a small passage length. Therefore, good inertial supercharging that matches the high-speed rotation range is performed, and the maximum output can be increased by reducing the intake air flow resistance due to the increase in the cross-sectional area of the passage.

Furthermore, since the high-speed intake passages 6A, 6B and the two intake ports 4A, 4B are set to have approximately the same passage cross-sectional area, swirl generation within the combustion chamber 3 due to the difference in intake air amount is suppressed, and from this point of view, The intake volumetric efficiency is also increased and higher output can be achieved.

By the way, since the low speed intake passage 18 is always open, the low speed intake passage 18 is always open even in the high speed rotation range.
Although intake air is supplied from the high-speed intake passage 6A, the passage cross-sectional area is smaller and the passage length is longer than that of the high-speed intake passage 6A, so the intake passage resistance is significantly large. The amount of intake air supplied from the passage 18 is extremely small compared to the high-speed intake passage 6A, and the swirl generated by the intake air supplied from the low-speed intake passage 18 almost disappears.

In addition, since the fuel injection valve 19 is not provided in the other high-speed intake passage 6B, only air is supplied from the intake port 4A, but the amount of intake air is large in the high-speed rotation range, and turbulence occurs in the combustion chamber 3. The flow mixes the fuel and air evenly enough to cause no problems.

Furthermore, by closing the intake valve that opens and closes the intake port 4A that communicates with the low-speed intake passage 18 later than the other intake valve, and by closing the intake valve earlier than the other intake valve, the overlap with the exhaust valve can be reduced in the low-speed rotation range. As a result, it is possible to reduce engine rotational vibration and idling rotational speed.

On the other hand, when the supercharging pressure of the compressor 23A increases to a lower set value (for example, 350 mmHg) or more, the diaphragm actuator 27 operates and the exhaust bypass valve 26 opens. As a result, during normal operation, as described above, the exhaust flow rate bypassing the turbine 23B is increased to suppress an increase in rotation of the turbine 23B and the compressor 23A, thereby suppressing an increase in supercharging pressure.

However, especially when the engine is operated at high speed under a high load, or when the exhaust bypass valve 26 seizes and fails, the supercharging pressure rises to exceed the lower set value.
In this case, when the boost pressure sensor 28 detects that the boost pressure is higher than the upper set value (for example, 400 mmHg),
The solenoid valve 11 is energized by the output of the control circuit 16 into which the signal has been input, and negative pressure is supplied to the pressure operating chamber 10d of the actuator 10, so that the on-off valves 7A, 7B
closes. As a result, the high-speed intake passages 6A, 6B
Since this is closed, the intake air flow rate is reduced, and an excessive rise in supercharging pressure can be promptly prevented to protect the engine 1 and the turbocharger 23.

In this way, excessive intake air is not released to the atmosphere or returned to the intake passage upstream of the compressor, unlike in the past, and an excessive rise in boost pressure can be prevented without causing deterioration of fuel efficiency or generation of noise. .

In this case, the intake air taken in through the air flow meter 29 is mixed with the fuel injected from the fuel injection valve 19 through the low-speed intake passage 18, and is then taken into the combustion chamber 3, so that engine operation is continued.

Note that since the low-speed intake passage 18 is always open via the throttle valve 12, there is no significant deceleration shock even when the high-speed intake passages 6A, 6B are closed, and drivability can be improved. Further, the control circuit 16 controls, after the boost pressure reaches the upper set value and the on-off valves 7A and 7B close,
Since they do not open until the pressure drops to a lower set pressure, it is possible to prevent hunting of the on-off valves 7A, 7B and deterioration of drivability due to sudden changes in output. Furthermore, when the boost pressure is equal to or higher than the upper set value, fuel injection may be stopped to promote suppression of excessive rise in the boost pressure.

FIG. 3 shows a second embodiment of the invention. However, since the configuration of the intake passage downstream of the compressor is the same as in the first embodiment, the same reference numerals will be used in the explanation, and other identical components will also be explained with the same reference numerals.

That is, the end of a rotating shaft 8 connecting on-off valves 7A and 7B interposed in two high-speed intake passages 6A and 6B is connected to an output rod 31a of an actuator 31 via a lever 9. Actuator 3
1 is a communication pipe 33 in which a return spring 31c is housed in a chamber defined on the side to which the output rod 31a of the diaphragm 31b is connected, and a pressure operating chamber 31d defined on the other side is interposed with a solenoid valve 32. It is connected to the intake passage 22 downstream of the compressor 23A (on the upstream side of the throttle valve) through the compressor 23A.

Here, when the boost pressure reaches an upper set value or higher, the solenoid valve 32 is energized by the control circuit 16, and the output port 3 connected to the upstream side of the communication pipe 33 is energized by the control circuit 16.
2a and the atmospheric port 32b, and then, when the boost pressure falls below a set value lower than the upper set value, it is de-energized and the output port 32a is connected to the communication pipe 3.
The switching operation is performed so as to communicate with the input port 33c connected to the downstream side of No. 3.

To explain the effect of this, in the low speed rotation range of the engine where the boost pressure is less than the set value, the pressure introduced from the intake passage 22 to the pressure operating chamber 31d via the communication pipe 33 is small, so the biasing force of the return spring 31c The output rod 31a is in the retracted position, and in this position, the on-off valves 7A and 7B are maintained in a fully closed state via the lever 9 and the rotating shaft 8.

In this case, as in the first embodiment, only the low-speed intake passage 18 is opened, and improvements in output, fuel efficiency, and exhaust composition in the low-speed rotation range can be obtained.

In addition, in the high speed range where the boost pressure is higher than the set value,
The output rod 31a extends while the return spring 31c is compressed, and the rotating shaft 8 is rotated via the lever 9, thereby opening the on-off valves 7A and 7B.

In this case, the two high-speed intake passages 6A and 6B are opened, and together with the increase in supercharging pressure, the maximum output in the high-speed rotation range can be improved as much as possible.

Furthermore, when the boost pressure reaches the upper set value or higher, the solenoid valve 32 is energized by the output from the control circuit 16, the pressure working chamber 31d is communicated with the atmospheric port 31b, and high pressure air is released to the atmosphere. The biasing force of the return spring 31c prevails and the output rod 31a is pulled in, closing the on-off valves 7A and 7B, thereby preventing excessive rise in supercharging pressure.

<Effects of the Invention> As explained above, according to the present invention, in a turbocharged internal combustion engine, two high-speed intake passages are connected to two intake ports of a combustion chamber and are each equipped with an on-off valve. and the low-speed intake passage, which is connected by bypassing one of the on-off valves, are selectively used by controlling the opening and closing of the on-off valve according to the engine speed range, so in the low-speed rotation range, the inertia In addition to improving output through supercharging and improving fuel efficiency and exhaust composition through swirl generation, in the high-speed rotation range, in addition to the supercharging effect from the turbocharger, inertia supercharging reduces intake air circulation resistance and eliminates swirl. Output can be improved as much as possible.

In addition, when the boost pressure becomes excessive, the on-off valve is closed and only the low-speed intake passage is opened to reduce the intake air flow rate. The feeder can be protected, and in this case,
Effects such as improved drivability can be obtained without adversely affecting the air-fuel mixture concentration or generating noise.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing the configuration of the intake system of the first embodiment of the present invention, FIG. 2 is a diagram showing the overall configuration of the same embodiment, and FIG. FIG. 1...Engine, 3...Combustion chamber, 4A, 4B...Intake port,
6A, 6B...High-speed intake path, 7A, 7B...Opening/closing valve, 8...Rotating shaft, 9...Lever, 10...Actuator, 11...Solenoid valve, 14...Negative pressure tank, 16...
Control circuit, 18...Low speed intake path, 22...Intake path,
31... Actuator, 32... Solenoid valve, 33... Communication pipe.

Claims (1)

[Claims] 1. A turbocharger equipped with a turbine rotationally driven by the exhaust flow of the engine, a compressor that rotates in conjunction with the turbine to supercharge intake air, and a supercharging pressure that detects the pressure of the supercharged intake air by the compressor. A detection means, two intake ports opening into the combustion chamber, two high-speed intake passages connected to the two intake ports, respectively, and interposed so as to simultaneously open and close each high-speed intake passage. two on-off valves, and a low-speed intake passage that is connected to one of the high-speed intake passages by bypassing the on-off valves and has a smaller passage cross-sectional area and a longer passage length than the high-speed intake passage; The two on-off valves are closed in a low engine speed range and open in a high engine speed range, and are unconditionally closed when the boost pressure detected by the boost pressure detection means is equal to or higher than a set value. An intake system for an internal combustion engine with a turbocharger, characterized in that the intake system includes an on-off valve control means for controlling an on-off valve.