JPS61244828A - Intake device of engine - Google Patents

Abstract

PURPOSE:To always suitably control a charging amount of intake air, by controlling in a correlating manner a recirculation control valve in an intake air recirculating passage and a throttle valve in accordance with an engine load, in the case of an engine equipped with an intake recirculating mechanism for reducing a pumping loss. CONSTITUTION:Each cylinder 1 opens to its combustion chamber 2 an intake port 5, communicating with an intake passage 4 branching from a surge tank 3, and a recirculation port 14 recirculating a part of intake introduced to the combustion chamber 2. Each recirculation port 14 is connected by recirculating passages 13 so as to communicate with each other, and the recirculating passage 13 sets a recirculation control valve 15 for controlling a recirculated amount from each cylinder 1. And a controller 23, setting a throttle valve 9 in an intake passage 6 to a predetermined initial opening when an engine is in low load operation, controls an intake charging amount by the recirculation control valve 15, while the controller, placing the recirculation control valve 15 in a fully closed condition when the engine is in high load operation, controls the intake charging amount by the throttle valve 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine equipped with an intake air recirculation mechanism for reducing pumping loss.

(Prior art) When the throttle valve is throttled down, intake resistance increases and pumping loss occurs, which worsens fuel efficiency. This problem occurs particularly in the low engine load range, and various proposals have been made to deal with this problem. One such method is to perform intake air recirculation, for example, as described in Japanese Patent Application Laid-Open No. 57-168041.
The engine is equipped with a recirculation passage that recirculates a portion of the intake air that has just been introduced into the combustion chamber, and by controlling the amount of intake air recirculated to this passage, the amount of intake air charged is controlled, thereby achieving a proper idle. An engine is disclosed that includes an intake air recirculation mechanism that maintains the rotational speed.

(Problems to be solved) However, with this disclosed engine, the problem of pumping loss during idling operation can be solved, but in that case, if you try to control the entire load range with only the amount of intake air recirculation, Unless the closing timing of the reflux valve is delayed until close to top dead center, the required reflux amount during idling cannot be obtained; There is a possibility that the amount of leakage from the valve will increase, making it impossible to obtain a sufficient amount of filling. In this case, a variable timing mechanism may be provided in the intake air recirculation valve, but the structure becomes complicated, which causes an increase in cost. Also,
The constant negative pressure state in the intake passage created by throttling the throttle valve is necessary for the operation of brake boosters, negative pressure actuators, etc.
Simply reducing the pumping loss due to intake throttling will cause other problems in the functionality of the device.

(Means for solving the above problems) The present invention has been constructed in view of the above circumstances, and the intake device of the present invention includes an intake passage that introduces intake air into the combustion chamber from an intake boat opening into the combustion chamber. a recirculation passage that recirculates a portion of the intake air introduced into the combustion chamber from a recirculation boat that opens into the combustion chamber; a recirculation valve that is provided to open and close the recirculation boat and closes later than the intake boat; The engine includes a throttle valve provided in the intake passage to control the amount of intake air flowing through the intake passage, and a recirculation control valve provided in the recirculation passage to control the amount of intake air recirculation.

According to the present invention, when the engine is operating at low load, the throttle valve is set to a predetermined initial opening degree and the recirculation control valve controls the intake air filling amount, and during high load operation, the recirculation control valve is fully closed. The intake air filling amount is controlled by the throttle valve, and
The engine is characterized in that the initial opening degree is set so that the engine generated torque when the throttle valve is initially opened matches the engine generated torque when the recirculation control valve is fully closed. That is, in the present invention, the intake air filling amount is controlled by
When the load on the engine increases and reaches a constant load state, control by the recirculation control valve is switched to control by the throttle valve. In this case, the torque generated by the engine is configured to change smoothly regardless of the switching of the control means.

(Description of Embodiment) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, the engine E of this example is a four-cylinder in-line engine, and the combustion chamber 2 of each cylinder 1 has an intake boat 5 communicating with a branch intake passage 4 branched from a surge tank 3. It's open. An air cleaner 7 is provided at the upstream end of the intake passage 6 extending upstream from the surge tank 3, and an air flow make 8 is provided downstream of the air cleaner 7. Further, a ζ throttle valve 9 is provided downstream of the air flow meter 8, and an injector 10 for injecting fuel is installed near the combustion chamber 2 of each branch intake passage 4. A bypass passage 11 that bypasses the throttle valve 9 is connected to the intake passage 6, and each bypass passage is provided with a bypass valve 12 that controls the amount of bypass intake air flowing through the passage 11. Further, the combustion chamber 2 is connected to a recirculation passage 13 that recirculates a portion of the intake air introduced into the combustion chamber 2 through the intake passage 4. The recirculation passage 13 opens into the combustion chamber 2 at a recirculation port 14. ing. A reflux control valve 15 for controlling the amount of reflux from each cylinder 1 is installed in the reflux passage 13 . These recirculation passages 13 are connected to communicate with each other, so that the intake air recirculated from each cylinder 1 is again sent to any other cylinder 1 during the intake stroke. Further, an exhaust port 17 of an exhaust passage 16 opens into the combustion chamber 2 . An intake valve 18 is provided at each of the three ports opening into the combustion chamber 2, that is, the intake port 5, the recirculation boat 14, and the exhaust port 17.
, a reflux valve 19, and an exhaust valve 20 are combined to open and close these boats at predetermined timing.

In this case, the recirculation valve 19 has an opening/closing timing that is slightly delayed from the intake valve 20, as shown in FIG. The throttle valve 9 is connected to a throttle servo motor 21a, and its opening degree is controlled by the morph. The throttle valve 9 is configured to move via the accelerator pedal 21 and the throttle servo motor 21a, and when the amount of depression of the accelerator pedal exceeds a predetermined value, it begins to open and responds to the increase in the amount of depression. The opening degree increases. Also,
The reflux control valve 15 is connected to a control motor 22 which is also a servo motor, and its opening degree is adjusted according to the operation of the control motor 22, so that the reflux amount can be controlled. It has become. In this example, as described above, the intake air amount is controlled by the throttle valve 9 and the bypass valve 12, and the recirculation amount is controlled by the recirculation control valve 15. In order to control the operations of the bypass valve 12 and the reflux control valve 15, in this example, a controller 23 preferably constituted by a microcomputer is provided. The controller 23 includes an air flow meter 8 that measures the amount of intake air, a throttle opening sensor 24 that detects the opening of the throttle valve 9, and a recirculation valve opening sensor 15a that detects the opening of the recirculation control valve. A pressure sensor 25 that detects the intake pressure downstream of the throttle valve 9 in the intake passage 6, a water temperature sensor 26 that is attached to the engine E and detects the engine cooling water temperature, and an 02 sensor 27 that detects the oxygen concentration in the exhaust gas. A signal from a rotation speed sensor 28 that detects the rotation speed is manually input. The controller 23 calculates these human signals and outputs control signals to the throttle servo motor 21a and the recirculation control valve 15 to control the intake air amount and recirculation amount, and also outputs command signals to the injector 10. is output to control the fuel injection amount.

Control of the intake air amount and recirculation amount in this example will be explained below with reference to FIGS. 3 and 4.

FIG. 3 is a flowchart for controlling the intake air amount and recirculation amount in this example. The controller 23 initializes the memory before starting control. Next, necessary data such as engine cooling water temperature, accelerator opening, and engine speed are read, and based on these data, a target intake air amount Q2 corresponding to the accelerator opening is calculated.

Then, it is determined whether the current operating state is within the range in which the recirculation amount control by the recirculation control valve 15 is performed based on the engine load state.
It is determined whether the intake air amount is within the range for controlling the intake air amount by the throttle valve 9, and depending on the result, a control command is issued to the recirculation control valve control motor 22 or the throttle servo motor 21a. In this case, if the current operating state is within the control range of the reflux control valve 15, the reflux valve opening calculation module determines the target intake air amount Q as shown in FIG.
Calculate the reflux control opening degree θ□ corresponding to 2. and,
After setting the opening degree of the throttle valve 9 to the initial opening degree, the target opening degree θn is set according to the difference from the actual opening degree θ of the recirculation control valve 150 from the recirculation control valve opening sensor 27.15a.
The control motor 22 is operated so that. In this example, the initial opening degree of the throttle valve 9 is set to θIH, and by keeping the bypass valve 12 open, the initial opening degree θIN of the throttle valve 9 can be substantially obtained. There is. Further, when the operating state of the engine is within a range in which intake air amount control should be performed by controlling the opening degree of the throttle valve 9, the controller 23 uses the throttle valve opening calculation module to control the target intake air amount Q6.
A target throttle opening degree θ7 corresponding to is calculated. In this case, the opening θ of the recirculation control valve 15 is set to 0, and the throttle is adjusted according to the difference between the actual throttle opening θTR from the throttle valve opening sensor 24 and the target throttle opening θ. The throttle servo motor 21a is operated so that the opening becomes the target throttle opening 0. Furthermore, although not shown in the flowchart, the controller 23 controls the fuel injection amount Q corresponding to the intake air amount θa.
, is corrected by various modules shown in FIG. 4, and an injection command signal is output to the injector 10.

By performing the above-described control, as shown in FIG. 5, in a region where the engine load is low, the throttle valve 9 is set to the initial opening degree θ! H is maintained, and the opening degree of the reflux control valve 15 decreases in proportion to the increase in load. Therefore, as the load increases, the amount of recirculation decreases and the amount of intake air charged into the combustion chamber increases. Then, when the engine load reaches a predetermined value, the recirculation control valve 15 is fully opened, and when the load increases thereafter, the opening degree of the throttle valve 9 increases accordingly. As a result, the intake air amount increases and the intake air filling amount increases. The system is configured so that there is no difference in the filling amount between when the reflux control valve 15 is fully closed and when the throttle valve 9 is initially opened. Therefore, the filling amount of intake air is controlled by the recirculation control valve 15 and the throttle valve 9.
Continuously increases as the load increases. In this example,
Although the bypass passage 11 and the bypass valve 12 are provided to set the actual initial opening degree θ,,l of the throttle valve 9, it is not necessary to do so, and the opening degree of the throttle valve is set to a predetermined opening degree. The initial opening degree may be ensured by setting the opening angle to .

(Effects of the Invention) According to the present invention, as described above, by controlling the recirculation amount by the recirculation control valve and controlling the intake air amount by the throttle valve, the engine can be operated in a wide range from the low load region to the high load region of the engine. The filling amount can be controlled smoothly. In other words, in the low load region, the recirculation amount can be controlled to control the filling amount while reducing the pumping loss, and in the high load region, the throttle valve can be controlled to ensure a sufficient intake filling amount. I can do it.

Furthermore, since the throttle valve 9 is provided, a constant negative pressure state can be created during low load, and therefore, the operation of the brake booster and the negative pressure actuator will not be hindered.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing valve timing, FIG. 3 is a flowchart showing an example of control according to the present invention, and FIG. The figure is an operating system diagram of the controller, and FIG. 5 is a graph showing changes in the opening degrees of the recirculation control valve and the throttle valve. E... Engine, 1... Cylinder, 4.6... Intake passage, 9... Throttle valve, 10... Injector, 12 ...Bypass valve, 15... Reflux control valve, 21a... Throttle servo motor, 22...
...Control motor.

Claims (1)

[Claims] An intake passage that introduces intake air into the combustion chamber from an intake port that opens into the combustion chamber, a recirculation passage that recirculates a part of the intake air introduced into the combustion chamber from a recirculation port that opens into the combustion chamber, and opens and closes the recirculation port. a recirculation valve provided in the recirculation passage and closing later than the intake port; a throttle valve provided in the intake passage for controlling the amount of intake air flowing through the intake passage; and a reflux control provided in the recirculation passage for controlling the amount of intake air recirculation. When the engine is running at low load, the throttle valve is set to a predetermined initial opening, and the recirculation control valve controls the amount of intake air, and when the engine is running at high load, the recirculation control valve is fully closed. The intake air filling amount is controlled by the throttle valve, and the initial opening is adjusted so that the engine generated torque at the initial opening of the throttle valve matches the engine generated torque when the recirculation control valve is fully closed. An engine intake system characterized by being set.