JPH03160152A - Intake system of internal combustion engine - Google Patents

Abstract

PURPOSE:To normally maintain proper resonance gain for intake air and enable a smooth response to variation of engine speed by performing compensation of the intake air according to increase/decrease in tank quantity when a resonator branched and connected to an intake passage is a variable tank volume type. CONSTITUTION:A connection passage 22 is branched and connected to an intake passage 10 between an air cleaner 7 and a throttle body 13, a cylindrical tank part 23 of a resonator 21 is connected to the tip end of the connection passage 22. A thread shaft 24 is rotatably supported inside the cylindrical tank part 23. A piston-shaped adjustment element 26 is moved by rotating the thread shaft 24 by means of a driving motor 25 controlled by an ECU 18 so as to vary the volume of the tank part 23. At the cylindrical tank part 23, rotary quantity of the thread shaft 24 is detected so as to provide a volume sensor 27 which detects increase/decrease in the volume. Detection air quantity by an air flow meter 9 is compensated based on output of the sensor 27, and calculation of real air quantity sent to a combustion chamber is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an intake system structure of an internal combustion engine installed in, for example, an automobile.

For example, in an engine installed in a car, when the intake valve opens and air is taken into the combustion chamber, the area near the intake valve becomes negative pressure, and the pressure wave of the negative pressure moves through the intake passage. There was a risk that the air would be returned to the combustion chamber side, reducing intake efficiency.

In order to prevent this decrease in intake efficiency, there is an intake system that includes a resonator branching from the engine's intake passage and having a certain tank capacity.

In this intake system, by providing a resonator branching from the intake passage, the negative pressure wave is reversed to a positive pressure wave at the branch point, and the positive pressure wave is sucked into the combustion chamber, causing a so-called resonance overflow. This improves intake efficiency.

This invention tries to solve the problem! Problem> In the conventional intake system described above, the resonator tank capacity is fixed, so depending on the engine rotation speed, sufficient resonance effect may not be obtained. There were limits to the speed range.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an intake system structure for an internal combustion engine in which resonant supercharging can always be performed efficiently regardless of the rotational speed range of the internal combustion engine.

Means for Solving the Problems> To achieve the above object, the present invention has a structure in which an air amount detection sensor for detecting the amount of incoming air is provided in the intake passage leading to the combustion chamber of the internal combustion engine, and the volume inside the tank is changed. A variable tank capacity type resonator is provided branchingly into the intake passage on the downstream side of the air amount detection sensor, and a volume detection means is provided in the resonator to detect an increase or decrease in the kunk volume of the resonator, and a volume detection means is provided in the resonator to detect the volume. The present invention is characterized by comprising a control device that corrects the amount of air detected by the air amount detection sensor based on the detection result of the means and calculates the actual amount of air sent to the combustion chamber.

Function: By variably adjusting the tank volume of the resonator, the resonant frequency is changed and the optimal resonant supercharging conditions are selected to match the rotational speed of the internal combustion engine. The amount of air detected by the air amount detection sensor and the actual amount of air sent to the combustion chamber differ depending on changes in the resonator tank volume. The amount of air detected by an air amount detection sensor is corrected by a control device so that even if the tank volume of a resonator changes, fuel can always be supplied according to the amount of air actually sent to the combustion chamber.

Embodiments FIG. 1 schematically shows the structure of an intake system of an internal combustion engine according to an embodiment of the present invention.

Intake #r1 enters the combustion chamber 2 of the engine l via the intake valve 3.
:4 is connected to the base end thereof, and an exhaust pipe 6 is connected to the combustion chamber 2 via an exhaust valve 5. An air cleaner 7 is attached to the tip of the intake pipe 4, and an air cleaner element 8 is housed in the air cleaner 7. A type air flow meter 9 is provided.

A butterfly-type throttle valve 11 is provided in the middle of the intake pipe 4 to adjust the amount of intake air supplied into the combustion chamber 2 by changing the opening degree of the intake air passage N10 formed by the intake pipe 4. 11 is opened by operating the accelerator pedal 12. A throttle body 13 in which the throttle valve 11 is incorporated is equipped with a throttle sensor l4 that detects the opening degree of the throttle valve 11. In addition, 17 in the figure is a surge tank forming a part of the intake vent 10.

Furthermore, the intake system structure shown in FIG. 1 is equipped with a crank angle sensor l5 and a water temperature sensor 16, and the detection information of the air flow meter 9, throttle sensor 14, crank angle sensor 15, and water temperature sensor I6 is sent to an electronic control unit (EC).
U) It is designed to be input to l8. The ECU 18 calculates A/N (the amount of air relative to the rotational speed of the engine 1) based on the input information, and the ECU 18 calculates the A/N.
A drive command is output to the spark plug 19 and the injector 20 in accordance with A/N, and the ignition timing and fuel amount are controlled in accordance with A/N. This allows operation at a predetermined air-fuel ratio.

A connection passage 22 (length L) of a resonator 21 is provided in a branched manner in the intake passage 10 between the air cleaner 7 and the throttle body 13, and the resonator 2 is connected to the tip of the connection passage 22.
One cylindrical tank portion 23 is connected. Connection passage 22
The diameter DS of the intake passage 10 and the diameter D of the intake passage 10 are formed to have approximately the same diameter. A screw shaft 24 is rotatably supported within the cylindrical tank portion 23, and the screw shaft 24 is driven and rotated by a drive motor 25 driven based on commands from the ECU 18. A piston-shaped regulator 26 is located inside the cylindrical tank portion 23.
The adjuster 26 is screwed onto the screw shaft 24. By rotating the screw shaft 24 by the drive motor 25, the adjuster 26 moves within the cylindrical tank portion 23, and the volume of the cylindrical tank portion 23 can be changed.

Therefore, by controlling the drive of the drive motor 25,
The volume of the resonator 21 can be variably adjusted. The cylindrical tank portion 23 is equipped with a volume sensor 27 as a volume detection means that detects the amount of rotation of the screw shaft 24 to detect an increase or decrease in volume, and the detected value of the volume sensor 27 is sent to the ECU.
1 to 8.

By the way, in general, according to Helmholt's resonator theory, if either the tank volume v1 of the resonator 21, the connecting passage diameter D, or the connecting passage length L is changed, resonance will occur.
We know that we can change the frequency. Therefore, by changing the tank volume V of the resonator 21, the resonance frequency can be changed, and even if the engine speed changes by changing the tank volume ■ of the resonator 21, the resonance frequency can be changed. Demonstrate the optimal state of resonance.

In this case, the resonator frequency range determined by the connection passage diameter D1 of the resonator 21, the connection passage length, and the tank volume V is 1 2 0 0 to 4 for the resonator alone.
Equivalent to 200 rpm (40~ for 4-cylinder engines)
It is desirable to set it to 1 4 0 1t phase y).

In addition, the resonance tuned engine rotation speed when the branching point of the connecting passage 22 of the resonator 21 in the intake passage 10 is set as the open end. The branch pipe passage #1 to the cylinder and the volume of air in the open state of the intake valve) and the intake vent FI from the branch pipe collection part of the intake manifold.
[Determined by the length of the connection line II 10 to the branch point of the connection line 22 and the main flow pipe diameter D2 of the intake passage 10] is 1 5 0
It is desirable to set the rotation speed to 0 to 2000 rpm, especially 1750 rpm (this rotation speed is AT$
It is most preferable to use a rotation speed that is often used when starting and accelerating.

Next, the operation of the intake system structure having the above configuration will be explained. The intake condition changes depending on the change in the rotational speed of the engine 1. According to the change in the rotational speed of the engine 1, a command from the ECU l 8 is transmitted to the drive motor 25, and the drive motor 25 is operated to open the cylinder of the resonator 21. Adjuster 26 in the shaped tank part 23
to adjust the volume V of the resonator 21. This allows the resonant frequency to be varied to obtain optimal conditions for resonating with the pulsation of the airflow.

Furthermore, since the diameter D2 of the intake vent wI10 and the diameter D of the connection passage 22 of the resonator 21 are approximately the same, the speed fluctuation at the connection part of the resonator 21 to the intake passage 10 becomes maximum during resonance. However, the loss due to the flow can be reduced, and the effect on resonance supercharging can be further increased.

By the way, depending on the volume of the resonator 21, the intake air scene detected by the air flow meter 9 and the actual combustion chamber 2 may differ.
There may be a difference in the amount of air supplied. That is,
When the volume of the resonator 21 becomes smaller, an amount of air larger than the amount of air detected by the air flow meter 9 flows into the combustion chamber 2.
This results in a state where the fuel is thinner than the stoichiometric air-fuel ratio (lean state). Conversely, when the volume of the resonator 21 increases, a phenomenon occurs in which the intake air is sucked into the resonator 21 side, so that an amount of air smaller than the amount of air detected by the air flow meter 9 is supplied to the combustion chamber 2. The fuel becomes richer than the stoichiometric air-fuel ratio. Therefore, the amount of air taken in from the air cleaner 7 and passing through the air flow meter 9 and the amount of air supplied to the combustion chamber 2 will be in error by the position change of the regulator 26, and the air-fuel ratio will become lean or rich, resulting in drivability. or deterioration of exhaust gas performance.

Therefore, in the intake system including the resonator 21 described above, the control described below should be performed. FIG. 2 shows the control flowchart.

Based on the detected values of the air flow meter 9, throttle sensor 14, crank angle sensor 15, and water temperature sensor 16, the amount of air (A/N+) for the rotational speed of the engine 1 is calculated and stored. Determine whether or not there has been a change in the detected value, that is, whether or not there has been a change in the volume of the resonator 21.If there has been no change in the volume, the pre-stored A/N is read out and this A/N is
Spark plug 19 and injector 20 based on the value of N
Outputs drive commands to.

On the other hand, if the volume sensor 27 determines that there has been a change in the volume of the resonator 21, for example, if it is determined that the volume has increased, the amount of air supplied to the combustion chamber 2 is smaller than the amount of air detected by the air flow meter 9. Therefore, a correction A/N (negative value) is calculated according to the volume increase amount ΔV. Read the A/N stored in advance and enter this A/N.
Add the correction A/N to the value of , and convert this added value into Δ(A/N).
N ) (in this case A/N) Δ(A/N)). Δ(
A/N) (an amount smaller than the actual value detected by the air flow meter 9), a drive command is output to the spark plug 19 and the injector 20.

Note that when it is determined that the volume has decreased, the correction A/N becomes a positive value, and A/N<Δ(A/N).

Therefore, even if the volume of the resonator 21 changes, the ignition timing and fuel amount are controlled by taking into account the amount of air corresponding to the change in volume with the amount of intake air detected by the air flow meter 9, so the air-fuel ratio is always set. The engine 1 can be operated in a state close to that in which resonance supercharging is possible. Also, resonator 2
Since the air amount is corrected and controlled using the capacitive sensor 27 that detects Pjm of 1, no special members are required, the structure is simple, and the cost does not increase.

<Effects of the Invention> The intake system structure of the internal combustion engine of the present invention uses a variable tank volume Ijk type raisonné and is equipped with a control device that corrects the intake air amount according to an increase or decrease in the tank volume. It is possible to always maintain a good resonance gain for the intake air in the intake passage according to the rotational speed of the internal combustion engine, and it is possible to smoothly respond to changes in rotational speed.Moreover, it is possible to always maintain the set empty level regardless of increases or decreases in tank volume. The internal combustion engine can be operated at close to the fuel ratio.

As a result, it is possible to expand the engine rotation range in which resonance supercharging is possible and improve drivability and exhaust gas performance.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an intake system structure of an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a control flowchart thereof. In the drawing, 1 is an engine, 2 is a combustion chamber, 4 is an intake pipe, 9 is an air flow meter, ]O is an intake passage, 18 is an electronic control unit (ECU), 21 is a resonator, 25 is a drive motor, and 26 is a regulator , 27 is a volume sensor.

Claims (1)

[Claims] An air amount detection sensor that detects the amount of incoming air is provided in the intake passage leading to the combustion chamber of the internal combustion engine, and a variable tank capacity type resonator whose tank internal volume can be changed is installed in the intake passage downstream of the air amount detection sensor. The resonator is provided with a volume detection means for detecting an increase or decrease in the tank volume of the resonator, and the air amount detected by the air amount detection sensor is corrected based on the detection result of the volume detection means. An intake system structure for an internal combustion engine, characterized by comprising a control device that calculates the actual amount of air sent to a combustion chamber.