JPS63179129A - Bypass valve control method for internal combustion engine having supercharger - Google Patents

Abstract

PURPOSE:To improve startability by rapidly opening a bypass valve, by a method wherein, when an engine is under starting, a pressure, having a comparatively high negative pressure, generated in an intake air passage located down a line from a supercharger is fed to an actuator. CONSTITUTION:A pressure, generated in an intake air passage 12, is fed to a negative pressure chamber 24e of an actuator 24 through an electromagnetic switch valve 26. According to the magnitude of a negative pressure introduced to the negative pressure chamber 24e, the opening of a bypass valve 23 situated in a bypass passage 22 is regulated. In this case, when it is decided by an ECU 20, based on the number of revolutions of an engine and a starter switch, that an engine 10 is under starting, the electromagnetic switching valve 26 is turned ON. Lines 27 and 29 are intercommunicated to feed a pressure, having a comparatively high negative pressure, generated in an intake air passage 12 situated down a line from a supercharger 16, to the negative pressure chamber 24e. This constitution attracts a diaphragm 24b by means of a comparatively high pressure, and rapidly opens the bypass valve 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bypass valve control method for an internal combustion engine equipped with a supercharger.

(Prior art) Conventionally, a supercharger such as a supercharger that is mechanically driven by the engine is placed in the intake passage of an internal combustion engine, and the supercharger provides supercharging to improve the output characteristics of the engine. There are known methods that aim to achieve this. A bypass passage that bypasses the supercharger is connected to the intake passage of this type of engine, a bypass valve is disposed in the middle of the bypass passage, and an electromagnetic clutch is interposed in the drive system of the supercharger. .

When the engine is in a low-load, low-speed operating range, the electromagnetic clutch is turned off to disable the supercharger, and the bypass valve is opened to allow a portion of the intake air supplied to the engine to bypass the supercharger. This is intended to reduce output loss due to driving the supercharger and pressure loss due to intake air being sucked in through the supercharger.

In order to open and close the bypass valve as described above,
An actuator that responds to negative pressure is connected to the bypass valve, and pressure generated in the intake passage downstream of the throttle valve and upstream of the supercharger is supplied to the actuator to control opening and closing of the bypass valve.

(Problem to be Solved by the Invention) However, while the engine is starting, the supercharger is not operating as described above, and immediately after starting, there is a problem in the intake passage downstream of the throttle valve and upstream of the supercharger. The pressure is approximately equal to atmospheric pressure, and the negative pressure supplied to the actuator is small, so the bypass valve is not open, so the supercharger acts as resistance in the intake passage, increasing pressure loss in the intake system.
The amount of air intake during starting was reduced, which had a negative effect on starting performance.

Furthermore, if the starter is operated while opening the throttle valve at startup, the pressure in the intake passage downstream of the throttle valve and upstream of the supercharger will decrease as the opening of the throttle valve increases, even if the engine starts rotating. The negative pressure required to open the engine could not be achieved, and the starting performance of the engine was increasingly hindered.

The present invention has been made to solve such problems, and an object of the present invention is to provide a bypass valve II a1 method for an internal combustion engine equipped with a supercharger, which improves engine startability.

(Means for Solving the Problems) In order to achieve the above-mentioned object, according to the present invention, a supercharger disposed in an intake passage downstream of a throttle valve of an internal combustion engine is operated at least at a low load of the internal combustion engine. In addition to being inoperative in a low-speed operating region, a bypass passage that bypasses the supercharger is connected to the intake passage, a bypass valve is disposed in the middle of the bypass passage, and the bypass valve is configured to respond to negative pressure. In the bypass valve control method, the bypass valve is controlled by connecting an actuator and supplying pressure generated in the intake passage downstream of the throttle valve to the actuator to open and close the bypass valve. Provided is a bypass valve control method for an internal combustion engine equipped with a supercharger, characterized in that internal pressure is supplied to the actuator by internal pressure in the intake passage downstream of the throttle valve and upstream of the supercharger at times other than starting. .

(Function) Immediately after startup, the pressure in the intake passage downstream of the turbocharger is lower than the pressure in the intake passage downstream of the throttle valve and upstream of the turbocharger by the amount of pressure loss caused by the turbocharger because the turbocharger is not operating. By supplying this pressure in the intake passage downstream of the turbocharger to the actuator instead of the pressure in the intake passage downstream of the throttle valve and upstream of the turbocharger, it becomes possible to open the bypass valve more reliably, and the intake passage Since a portion of the fuel is supplied to the engine through the opened bypass passage, it is possible to improve the startability of the engine.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a bypass valve w control device for implementing the method of the present invention, and reference numeral 10 in the figure indicates an internal combustion engine such as a gasoline engine, to which an intake pipe 12 is connected. An air cleaner 13 is attached to the end of the intake pipe 12 that is open to the atmosphere, and a Karman vortex type air flow sensor 14 that detects the air flow rate A taken into the engine 10 is disposed.
is electrically connected to the electronic control unit (ECU), which will be described later.
) 20 to provide an air flow detection signal to the electronic control unit 20.

A throttle valve 15 is disposed in the middle of the intake pipe 12, and a supercharge valve 16 is disposed in the intake pipe 12 between the throttle valve 15 and the engine 10. During this supercharging, reference numeral 16 is a roots-type supercharger mechanically driven by the engine 10, and connection with the engine 10 is controlled by an electromagnetic clutch 17. That is, the electromagnetic clutch 17 is connected to the output side of the electronic control unit 20, is energized by a drive signal from the electronic control unit 20, becomes on (engaged), and operates the supercharger 16.

A bypass passage 22 that bypasses the supercharger 16 is connected to the intake pipe 12.
One end is connected to the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16, and the other end is connected to the supercharger 1.
6 are in communication with the downstream intake pipes 12, respectively.

A bypass valve 23 that opens and closes the bypass passage 22 is disposed in the middle of the bypass passage 22, and the bypass valve 23 opens and closes the bypass passage 22.
is driven by an actuator 24 that responds to negative pressure via its valve shaft 23a.

The actuator 24 includes a housing 24a, an atmospheric chamber 24d that communicates the inside of the housing 24a with the atmosphere, and a negative pressure chamber 24e. 2411
The spring 24C is housed in the diaphragm 24C and presses the diaphragm 24b in a direction to close the bypass valve 23.

Reference numeral 26 in FIG. 1 is an electromagnetic switching valve, and this electromagnetic switching valve 26 has three boats 26a to 26C.
The valve body 26d selectively switches and closes either the boat 26c or the boat 26c, and a solenoid 26e that switches the valve body 26d.The solenoid 26e is connected to the output side of the electronic control unit 20 and It is energized by an energizing signal from the control unit 20. When the solenoid 26e is energized, the valve body 26d moves toward the boat 26b to close the boat 26b, and when the solenoid 26e is deenergized, a spring (not shown) closes the boat 26.
Move to the position where C is closed.

One end of a conduit 27 is connected to the negative pressure chamber 24e of the actuator 24, and the other end of the conduit 27 is connected to the boat 26a of the electromagnetic switching valve 26. One end of a pipe 28 is connected to the boat 26b of the electromagnetic switching valve 26, and the other end of the pipe 28 is connected to a boat 12b provided in the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16. One end of a pipe line 29 is connected to the boat 26C of the electromagnetic switching valve 26, and the other end of the pipe line 29 is connected to the boat 26C of the electromagnetic switching valve 26.
6 is connected to a boat 12a provided in the intake pipe 12 downstream.

Various sensors are provided on the input side of the electronic control unit 20, such as a throttle opening sensor 30 that detects the valve opening of the throttle valve 15, and an engine rotation sensor that is attached to a camshaft (not shown) and that detects the rotational speed of the engine 10. A starter switch sensor 32 that detects the on/off state of a starter switch that operates a starter (not shown) is connected, and these sensors supply detection signals to the electronic control unit 20.

Next, the operation of the bypass pulp control device configured as described above will be explained with reference to FIGS. 2 and 3.

First, in the negative pressure chamber 24e of the actuator 24, the pressure generated in the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16 and the pressure generated in the intake pipe 12 downstream of the supercharger 16 are applied to the negative pressure chamber 24e of the electromagnetic switching valve 26. Selectively supplied by switching. And this negative pressure chamber 24
Bypass valve 2 depending on the magnitude of negative pressure supplied to e.
The valve opening degree (stroke) of No. 3 changes as shown in FIG.

That is, when the negative pressure supplied to the negative pressure chamber 24e is small, the spring force of the spring 24C is stronger and the bypass valve 23 remains closed, but when the negative pressure exceeds the predetermined value PL, the spring force of the spring 24C In response, the bypass valve 23 begins to open, and when the predetermined value P2 is reached, the bypass valve 23 becomes fully open.

When the engine 10 is operated in a predetermined high-load operating range, the electronic control unit 20 supplies a drive signal to the electromagnetic clutch 17 and turns it on (engages) to operate the supercharger 16. During low load and low rotation, such as idling, the electromagnetic clutch 17 is turned off (released) and the supercharger is rendered inactive.

FIG. 3 is a flowchart showing a control procedure for the bypass valve 23. First, the electronic control unit 20 executes step 41 in FIG. 3 to determine whether the engine 10 is being started. This determination is performed, for example, based on the detection signals of the engine rotation speed sensor 31 and the starter switch sensor 32, and the starter (not shown) is in operation (on) and the engine rotation speed is a predetermined rotation speed (for example, 4
50 rpm), it is determined that the engine 10 is being started.

When the electronic control unit 20 determines that the engine IO is starting based on the detection signals from the engine rotation speed sensor 31 and the starter switch sensor 32, that is, when the determination result in step 41 is affirmative (Yes),
Proceeding to step 43, an energizing signal is output to the 'Eiff switching valve 26 to turn it on. When the electronic control unit) 20 outputs an energizing signal to the electromagnetic switching valve 26, the pipe line 27 and the pipe line 29 are communicated, and the pressure generated in the intake pipe 12 downstream of the supercharger 16 is stored in the negative pressure chamber 24e. will be supplied. At this time, the supercharger 16 is in an inactive state, and the pressure inside the intake pipe 12 downstream of the supercharger 16 is increased by the amount that the supercharger 16 becomes the resistance of the intake system. 12 internal pressure (large negative pressure), and when this pressure is supplied to the negative pressure chamber 24e, the diaphragm 24b becomes lower than the pressure inside the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16 than when the internal pressure of the intake pipe 12 is supplied. It will be pulled toward the right side in the figure with a large force, making it possible to open the bypass valve 23 quickly after starting.

On the other hand, the rotation of the engine 10 increases and becomes equal to or higher than the predetermined rotation speed, and the engine 10 is in a starting state (cranking state).
If the above step 41 is cleared, the determination result in step 41 is negative (NO
), and in such a case, the electronic control unit 20 proceeds to step 42 and turns off the electromagnetic switching valve 26 without outputting an energizing signal. When the electronic control unit 20 does not output an energizing signal to the electromagnetic switching valve 26, the pipe line 27 and the pipe line 28 are communicated with each other, and the negative pressure chamber 24e is provided with the air in the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16. The pressure generated in When the engine IO exits the starting state, the engine speed has also increased to near the idle speed, and when the throttle valve 15 is in the closed state, this occurs in the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16. The pressure is negative enough to open the bypass valve 23, and even if the supply pressure to the negative pressure chamber 24e is switched to this pressure, the bypass valve 23 can be kept open. In this way, the startability of the engine 10 can be improved, and the engine 10 during idling operation immediately after starting can be improved.
The operation of the system can be stabilized.

Note that when the throttle valve 15 is opened after startup, the bypass valve 23 is opened and closed according to the negative pressure in the intake pipe 12 downstream of the throttle valve 15 and upstream of the supercharger 16.
When this negative pressure falls below the predetermined negative pressure shown in FIG. 2 (when the absolute pressure rises), the valve is closed.

In the above embodiment, a supercharger is used as the supercharger, but the present invention is not limited thereto, and a turbocharger or the like may be used.

(Effects) As detailed above, according to the bypass valve control method for an internal combustion engine equipped with a supercharger according to the present invention, the pressure in the intake passage downstream of the supercharger is controlled when starting the internal combustion engine, and when the internal combustion engine is not started, the pressure is Since the pressure in the intake passage downstream of the valve and upstream of the supercharger is supplied to the actuator that opens and closes the bypass valve in response to negative pressure, the bypass passage is opened during engine startup and intake air is drawn from this passage. A portion of the fuel can be supplied to the engine, reducing pressure loss in the intake system and improving engine startability.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram showing the overall configuration of a bypass valve control device that implements the bypass valve control method for an internal combustion engine equipped with a supercharger according to the present invention, and FIG. A graph showing the relationship between the opening degree (stroke) of the bypass valve 23 shown in FIG. 1 and the magnitude of negative pressure supplied to the negative pressure chamber 24e of the actuator 24, and FIG. 3 shows the electronic control unit 20 of FIG. 3 is a flowchart showing a bypass valve control procedure executed by. 10... Internal combustion engine, 12... Intake passage, 14.
...Air flow sensor, 15...Throttle valve, 16
...Supercharger (supercharger), 20...Electronic control unit, 22...Bypass passage, 23
...Bypass valve, 24...Actuator, 2
4e... Negative pressure chamber, 26... Solenoid switching valve, 30...
Throttle opening sensor, 31... Engine speed sensor, 32... Starter switch sensor. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagato Figure 1 Figure 2

Claims (1)

[Claims] A supercharger disposed in an intake passage downstream of a throttle valve of the internal combustion engine is made inoperative at least in a low load, low rotational operating region of the internal combustion engine, and a bypass passage is provided in the intake passage to bypass the supercharger. A bypass valve is disposed in the middle of the bypass passage, an actuator responsive to negative pressure is connected to the bypass valve, and pressure generated in the intake passage downstream of the throttle valve is supplied to the actuator. In the bypass valve control method for opening and closing a bypass valve, when the internal combustion engine is started, the pressure in the intake passage downstream of the supercharger is controlled, and when the internal combustion engine is not started, the pressure in the intake passage downstream of the throttle valve and upstream of the supercharger is controlled. A method for controlling a bypass valve of an internal combustion engine equipped with a supercharger, characterized in that the bypass valve is supplied to an actuator.