JPH05125947A - Intake control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To simplify the structure of an intake control device by using a common actuator to drive both a supercharger bypass control valve disposed within a supercharger bypass passage and an intercooler bypass control valve for controlling circulation of intake air within an intercooler bypass passage. CONSTITUTION:A bypass passage 8 branches from the portion of an intake passage 2 between a mechanical supercharger 4 and a throttle valve 7. A supercharger bypass control valve 11 is disposed inside the supercharger bypass passage 8. Also, an intercooler bypass passage 9 branches from the portion of the intake passage 2 between the mechanical supercharger 4 and an intercooler 5. An intercooler bypass control valve 12 is provided which controls circulation of intake air within the intercooler bypass passage 9. The supercharger bypass control valve 11 and the intercooler bypass control valve 12 are connected to a common actuator 16 via a common valve shaft 15. The structure of the intake control device can thus be simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control system for an internal combustion engine.

[0002]

2. Description of the Related Art An engine-driven mechanical supercharger is arranged in an engine intake passage, a bypass passage is provided for connecting an upstream side and a downstream side of the mechanical supercharger, and a bypass control valve is provided in the bypass passage. There is known an internal combustion engine in which an intake air amount supplied to the engine cylinder is controlled by controlling an intake air amount returned to an upstream side of a mechanical supercharger via a bypass passage.

However, in such an internal combustion engine, the temperature of the intake air supplied to the engine cylinder rises because the intake air is heated when passing through the mechanical supercharger. Therefore, in such an internal combustion engine, normally, the temperature of the intake air supplied to the engine cylinder is lowered so as to obtain a high charging efficiency during high engine load operation. The cooler is arranged. However, when the intercooler is arranged in the intake passage downstream of the mechanical supercharger in this manner, the intake air temperature supplied to the engine cylinder becomes too low during engine low load operation, resulting in a problem that combustion deteriorates. ..

Therefore, the bypass passage connected to the upstream side of the mechanical supercharger is branched into a pair of bypass passages via a switching valve, and one bypass passage is provided in the intake passage between the mechanical supercharger and the intercooler. An internal combustion engine is known in which the other bypass passage is connected to the intake passage downstream of the intercooler (see Japanese Utility Model Laid-Open No. 1-133628). In this internal combustion engine, at the time of engine high load operation, a part of the relatively low temperature intake air discharged from the intercooler due to the switching action of the switching valve is passed through the switching valve and the bypass control valve into the intake passage upstream of the mechanical supercharger. The temperature of the intake air supplied to the engine cylinder is lowered by supplying the returned intake air to the engine cylinder via the intercooler again. A part of the relatively high temperature intake air discharged from the mechanical supercharger due to the switching action is returned to the intake passage upstream of the mechanical supercharger via the switching valve and the bypass control valve, and the returned intake air is returned. By supplying the air into the engine cylinder through the intercooler, the temperature of the intake air supplied into the engine cylinder does not drop so much.

[0005]

However, this internal combustion engine has a problem that the structure becomes complicated because the bypass control valve and the switching valve that are separately controlled must be provided.

[0006]

In order to solve the above problems, according to the present invention, an engine-driven mechanical supercharger is arranged in the engine intake passage and an intake passage downstream of the mechanical supercharger is provided. An intercooler is installed in the air conditioner, the intake passage between the mechanical supercharger and the intercooler is branched to the supercharger bypass passage, and this supercharger bypass passage is connected to the intake passage upstream of the mechanical supercharger. In an intake control device for an internal combustion engine in which a supercharger bypass control valve driven by an actuator is arranged in the feeder bypass passage, the intercooler bypass passage is branched from the intake passage between the mechanical supercharger and the intercooler. An intercooler bypass passage is connected to an intake passage downstream of the intercooler to bypass the intercooler and control the flow of intake air flowing in the intercooler bypass passage. A cooler bypass control valve is installed and this intercooler bypass control valve is driven by the above-mentioned actuator.When the engine is operating under high load, the supercharger bypass control valve closes the supercharger bypass passage and the intercooler bypass control valve causes the intercooler bypass control valve to operate. By shutting off the intake air flow in the bypass passage and supplying all the intake air discharged from the mechanical supercharger to the engine through the intercooler, the supercharger bypass control valve is used to bypass the supercharger bypass control valve during low engine load operation. While opening the passage, the intercooler bypass control valve allows the intake air to flow through the intercooler bypass passage.

[0007]

The supercharger bypass control valve and the intercooler bypass control valve are driven by the same actuator.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 is an engine body, and 2 is an intake passage extending from the engine body 1 to an air cleaner 3.
An engine-driven mechanical supercharger 4 is arranged in the intake passage 2, and an intercooler 5 is arranged in the intake passage 2 downstream of the mechanical supercharger 4. Air cleaner 3 and mechanical supercharger 4
A throttle valve 7 connected to an accelerator pedal 6 is arranged in the intake passage 2 between them. A supercharger bypass passage 8 branches from the intake passage 2 between the mechanical supercharger 4 and the throttle valve 7. The supercharger bypass passage 8 is an intake passage 2 between the mechanical supercharger 4 and the intercooler 5. Connected to. Also,
An intercooler bypass passage 9 branches from the intake passage 2 between the mechanical supercharger 4 and the intercooler 5, and the intercooler bypass passage 9 is connected to the intake passage 2 downstream of the intercooler 5.

A supercharger bypass control valve 11 is disposed in the supercharger bypass passage 8 and cooperates with a valve port 10 formed in the supercharger bypass passage 8. As shown in FIG. 1, the supercharger bypass control valve 11 has a conical shape. Therefore, as the supercharger bypass control valve 11 moves away from the valve port 10, the supercharger is controlled from the downstream side of the mechanical supercharger 4. It can be seen that the amount of intake air returned to the upstream side of the mechanical supercharger 4 via the machine bypass passage 8 increases.

On the other hand, an intercooler bypass control valve 12 is arranged in a portion of the intake passage 2 where the intercooler bypass passage 9 branches. The intercooler bypass control valve 12 has a flat plate shape and is arranged between the intake passage inlet port 13 communicating with the intercooler 5 and the inlet port 14 of the intercooler bypass passage 9. The supercharger bypass control valve 11 and the intercooler bypass control valve 12 are connected to a common actuator 16 via a common valve shaft 15.

The actuator 16 has a negative pressure chamber 19 separated from an atmospheric pressure chamber 18 by a diaphragm 17.
The valve shaft 15 is connected to the diaphragm 17, and the negative pressure chamber 19 is connected.
A diaphragm pressing compression spring 20 is inserted therein.
The negative pressure chamber 19 is connected to an engine-driven negative pressure pump 23 via a negative pressure equalizing pipe 21 and an electromagnetic switching valve 22 that can communicate with the atmosphere, and the negative pressure equalizing pipe 21 has an absolute pressure inside the negative pressure chamber 19. A pressure sensor 24 for detecting is detected. Solenoid switching valve 2
2 is duty ratio controlled based on the output signal of the electronic control unit 30.

The electronic control unit 30 comprises a digital computer, and a ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, and an input port 35 which are mutually connected by a bidirectional bus 31. And an output port 36. The pressure sensor 24 generates an output voltage proportional to the absolute pressure in the negative pressure chamber 19, and this output voltage is the AD converter 37.
Is input to the input port 35 via. Throttle valve 7
A throttle sensor 38 for generating an output voltage proportional to the throttle opening is attached to the input port 3 via the AD converter 39.
Input to 5. Further, the input port 35 is connected to a rotation speed sensor 40 that generates an output pulse representing the engine rotation speed. On the other hand, the output port 36 is connected to the electromagnetic switching valve 22 via the drive circuit 41.

FIG. 2 shows the relationship between the target opening θ of the supercharger bypass control valve 11 and the throttle opening TA. Figure 2
As can be seen from the above, the smaller the throttle opening TA, the larger the target opening θ of the supercharger bypass control valve 11,
Therefore, as the throttle valve opening TA decreases, the amount of intake air returned to the upstream side of the mechanical supercharger 4 via the supercharger bypass passage 8 increases. That is, the ratio of the intake air amount supplied into the engine cylinder to the total intake air amount discharged from the mechanical supercharger 4 decreases as the throttle valve opening TA decreases. At this time, as shown in FIG. 2, when the throttle valve opening TA is the same, the target opening θ of the supercharger bypass control valve 11 increases as the engine speed N increases. On the other hand, when the throttle opening TA becomes large, the supercharger bypass control valve 11 is held in the fully closed state,
Therefore, at this time, all the intake air discharged from the mechanical supercharger 4 is supplied into the engine cylinder.

In the embodiment shown in FIG. 1, the relationship between the opening degree of the supercharger bypass control valve 11 and the absolute pressure in the negative pressure chamber 19 has been previously obtained by an experiment, and the supercharger bypass control valve 11 is opened. Pressure chamber 1 required to reach the target opening θ shown in FIG.
Absolute pressure PO in 9 is throttle opening TA and engine speed N
Is stored in advance in the ROM 32 in the form of the map shown in FIG. Therefore, in the embodiment shown in FIG. 1, the absolute pressure PO shown in FIG. The ratio of the time when is connected to the negative pressure pump 23 and the time when it is opened to the atmosphere is controlled.

Next, the duty ratio control routine will be described with reference to FIG. This routine is executed by interruption at regular time intervals. Referring to FIG. 4, first, at step 50, the target pressure PO is calculated from the relationship shown in FIG. Next, at step 51, it is judged if the absolute pressure P detected by the pressure sensor 24 is higher than the absolute pressure (PO + a) obtained by adding the constant value a to the target pressure PO. When P> PO + a, the routine proceeds to step 52, where the duty ratio DT is increased by K, whereby the absolute pressure P is decreased. On the other hand, P ≦ PO + a
If so, the routine proceeds to step 53, where it is judged if the absolute pressure P detected by the pressure sensor 24 is lower than the absolute value (PO-b) obtained by subtracting the constant value b from the target pressure PO.
When P <PO-b, the routine proceeds to step 54, where the duty ratio DT is decreased by K, and thereby the absolute pressure P is increased. In this way, the opening degree of the supercharger bypass control valve 11 is controlled to the target opening degree θ shown in FIG.

FIG. 5 shows the opening θ of the supercharger bypass control valve 11 when the engine speed is constant, the opening θh of the intercooler bypass control valve 12 with respect to the inlet port 14 of the intercooler bypass passage 9, and the interface. FIG. 5 shows the relationship between the opening θc of the intercooler bypass control valve 12 with respect to the inlet port 13 communicating with the cooler 5 and the throttle valve opening TA. Further, FIG. 5 shows the supply to the engine cylinder when the engine speed is constant. Total intake air amount Qtota
1, an intake air amount Qc supplied into the engine cylinder through the intercooler 5, and an intake air amount Q supplied into the engine cylinder through the intercooler bypass passage 9.
The relationship between h and the throttle valve opening TA is shown.

As can be seen from FIGS. 1 and 5, when the throttle opening TA becomes large and the supercharger bypass control valve 11 is fully closed, the intercooler bypass control valve 12 fully closes the valve port 14 accordingly. , Fully open the valve port 13. Therefore, during engine high load operation with a large throttle opening TA, all intake air discharged from the mechanical supercharger 4 is supplied into the engine cylinder through the intercooler 5. Therefore, the temperature of the intake air supplied into the engine cylinder is lowered by the intercooler 5, and thus a high charging efficiency is obtained during engine high load operation.

On the other hand, when the throttle opening TA decreases and the supercharger bypass control valve 11 opens, the intercooler bypass control valve 12 opens the valve port 14 accordingly. Therefore, at this time, part of the intake air is supplied into the engine cylinder through the intercooler bypass passage 9, and part of the intake air is supplied into the engine cylinder through the intercooler 5.

On the other hand, when the throttle opening TA is further reduced, that is, when the idling operation state or the low load operation state is reached, the intercooler bypass control valve 12 almost closes the valve port 13, and most of the intake air is intercooler bypassed. It is supplied into the engine cylinder via a passage 9. Therefore, when the combustion is inherently unstable, such as during the idling operation or the low load operation, the intake air temperature is hardly decreased, and good combustion can be obtained.

As can be seen from FIG. 2, the opening degree of the supercharger bypass control valve 11 is controlled according to the engine speed N even during idling operation. Therefore, in the embodiment shown in FIG. However, the intercooler bypass control valve 12 does not keep the valve port 13 completely closed. However, by elastically connecting the intercooler bypass control valve 12 to the valve shaft 15, the supercharger bypass control is performed while keeping the valve port 13 completely closed by the intercooler bypass control valve 12 during idling operation. The opening degree of the valve 11 can be controlled according to the engine speed N.

Further, in the embodiment shown in FIG. 1, the refrigerant is constantly circulated in the intercooler 5 while the engine is operating, so that the intake air is absorbed in the intercooler 5 as in the engine low load operation.
When almost no fluid is circulated in the interior, the temperature of the intercooler 5 itself is considerably lowered by the circulation action of the refrigerant. Therefore, the intake air supplied into the engine cylinder when the engine is in the high load operation state after the acceleration operation is performed after the low load operation is continued is strongly cooled by the intercooler 5.

[0022]

Since the supercharger bypass control valve and the intercooler bypass control valve are both controlled by one actuator, the structure of the intake control device can be simplified.

[Brief description of drawings]

FIG. 1 is an overall view of an intake control device.

FIG. 2 is a diagram showing a target opening degree of a supercharger bypass control valve.

FIG. 3 is a diagram showing a target pressure.

FIG. 4 is a flowchart for controlling a supercharger bypass control valve.

FIG. 5 is a diagram showing an opening degree of each intercooler bypass control valve with respect to each valve port.

[Explanation of symbols]

 2 ... Intake passage 4 ... Mechanical supercharger 5 ... Intercooler 8 ... Supercharger bypass passage 9 ... Intercooler bypass passage 11 ... Supercharger bypass control valve 12 ... Intercooler bypass control valve 16 ... Actuator

Claims (1)

[Claims] 1. An engine-driven mechanical supercharger is arranged in an engine intake passage, and an intercooler is arranged in an intake passage downstream of the mechanical supercharger, and an intake air between the mechanical supercharger and the intercooler is arranged. A supercharger bypass control valve driven by an actuator in the supercharger bypass passage by branching the supercharger bypass passage from the passage to connect the supercharger bypass passage to an intake passage upstream of the mechanical supercharger. In the intake control device for an internal combustion engine, the intercooler bypass passage is branched from the intake passage between the mechanical supercharger and the intercooler, and the intercooler bypass passage is connected to the intake passage downstream of the intercooler. An intercooler bypass control valve for controlling the flow of intake air flowing in the intercooler bypass passage by bypassing the intercooler bypass control valve. When the engine is operating under high load, the turbocharger bypass control valve closes the turbocharger bypass passage, and the intercooler bypass control valve shuts off the intake air in the intercooler bypass passage to prevent mechanical overload. All intake air discharged from the feeder is supplied to the engine via the intercooler, and the turbocharger bypass control valve opens the turbocharger bypass passage and the intercooler bypass control valve opens the intercooler bypass during low engine load operation. An intake control device for an internal combustion engine, which allows intake air to flow through a passage.