JPS63198726A - Turbocharger ventilation control method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ventilation control method for a supercharger disposed midway through an intake passage of an internal combustion engine.

(Prior Art) A mechanical supercharger such as a supercharger driven by the engine is disposed in the intake passage of an internal combustion engine,
2. Description of the Related Art A supercharger is known in which the air supplied to an engine is pressurized to improve the output of the engine. The rotor of this supercharger is rotatably supported by a housing via a bearing, and the bearing is lubricated with grease or the like. The clearance space near the rotor bearing, which is formed between the ends of the rotor and the inner peripheral surface of the housing, is filled with pressurized air during supercharging by the turbocharger, and the pressure becomes higher than that of the atmosphere. There is a problem in that grease leaks from the clearance space through the bearing into the atmosphere outside the housing, causing the aforementioned grease to be washed away and causing seizure of the bearing.

In order to eliminate this inconvenience, a hennulation passage is provided that communicates the clearance space with the intake passage upstream of the throttle valve, and a control valve (hereinafter referred to as this) is provided in the middle of the hennulation passage for opening and closing the pennarration passage. (referred to as a "ventilation valve"), the ventilation valve is turned on and off according to the operating state of the internal combustion engine, and the clearance space is communicated with the intake passage having a substantially atmospheric pressure state upstream of the throttle valve. This balances the pressure inside and outside the housing of the bearing to prevent grease, etc. that lubricates the bearing from flowing out.

In addition, during operation with a small engine load such as when idling, the throttle valve is bypassed and air is blocked from flowing into the engine via the 8-ventilation passage and the clearance space, thereby reducing the idle speed due to excessive intake air. A pen narration control method for a supercharger that prevents rise is known.

In addition, the valve opening degree of a bypass valve (hereinafter referred to as "RLSC pulp") installed in a bypass passage that bypasses the throttle valve during idle operation of the internal combustion engine is fed back according to the detected engine speed value and the target idle speed. A control method (hereinafter referred to as "ISC control") is known in which the intake air meter is increased or decreased during idling operation to stabilize the idling rotation.

Furthermore, the internal combustion engine is equipped with an electronic ignition timing control device, which controls the ignition timing of the engine according to variables representing the engine speed and engine load, such as a parameter value A/N calculated from the intake air amount A and the engine speed N. A method of controlling ignition timing is known in which the ignition timing is set to an optimal value depending on the operating state. This ignition ill control method normally sets the ignition timing in an advanced direction when the engine speed increases, and in a retarded direction when the parameter value A/N increases by 1. The electronic ignition timing control device is also used to control the engine speed during idle operation, depending on the difference between the detected engine speed and the target idle speed, and when the detected engine speed is higher than the target idle speed. The ignition timing is retarded, and when low, the ignition timing is advanced to stabilize idle rotation.

However, in both the above-mentioned ISC control and ignition time control, the engine speed is not yet stable immediately after the internal combustion engine starts, so after the engine reaches a complete explosion state, the engine speed rises once. After that, open-loop control is normally performed until the engine speed decreases to the target idle speed or the vicinity thereof.

(Problems to be Solved by the Invention) The opening and closing of the hennulation valve in the conventional supercharger pennarration control method described above represents, for example, intake air agitation per 1 intake amount, that is, the magnitude of the engine load. It is determined whether the parameter value A/N is less than or equal to a predetermined value, and the ventilation valve is closed when the parameter value A7N is less than or equal to the predetermined value.

However, there is an operating state in which the engine speed is extremely low when the engine is first started, and the parameter value A/N is larger than the predetermined value. If the above-mentioned parameter A/N value is used to determine whether the bench lane valve is open or closed when starting the engine, the hennulation valve will be opened and air will flow into the engine through the hennulation passage and the clearance space. However, the throttle valve is bypassed and intake air that is not metered by the throttle valve is supplied to the engine.

If the amount of intake air increases recklessly when the engine is started, there is a problem in that the engine speed increases immediately after the engine starts, and the engine speed drops significantly after this increase, and hunting may occur in some cases.

Fig. 3 explains the hunting phenomenon at the time of starting, and shows the ISC control and ignition time control immediately after the engine starts when the conventional hennulation control is executed.
It shows changes over time in the valve opening degree of the SC valve, the ignition timing, and the engine speed. ! In order to improve engine startability, the SC valve is kept fully open until the engine reaches a complete explosion state at time 11 in FIG. 3. Su o immediately after starting
The negative pressure in the intake road downstream of the nozzle valve is smaller than the negative pressure in the intake road during idling operation in a steady state, because even when the throttle valve is fully open, air has just begun to be supplied into the engine cylinder. It's small. Therefore, in combination with the fact that the ISO valve is fully opened and the pendant lane passageway is opened, the engine speed N increases rapidly (Fig. 3 tc) from time 1 to time t3. while)
. At this time, the ignition timing control device advances the ignition timing toward the optimum ignition timing as the engine speed increases (
(See Figure 3 fb)) Acts in the direction of promoting engine speed.Advancing the ignition timing during near-idle operation increases the engine speed, and retarding it causes it to decrease), engine speed It blows more and more rapidly.''

In order to make the engine speed quickly reach the target idle speed (fast idle speed), ISO control
The valve opening of the SC valve is rapidly closed at a predetermined valve closing speed from the time when the engine reaches a complete explosion state until it reaches a predetermined valve opening (see Fig. 3 (at tl-t2 in Fig. 3). ), then the valve is slowly closed at a speed slower than the predetermined valve closing speed until the target valve opening degree is reached (L2 to t4 in Fal in Figure 3).
When the opening degree of the ISC valve is controlled in this way, the engine speed drops rapidly after time t3 in Figure 3.
At time t4 in FIG. 3, the target idle rotation speed is crossed and further lowered. At this time, since the change in the engine speed N is larger than the change in the intake air i1A, the parameter value A/N increases, and the ignition timing is set in the retarded direction (the third
(see figure fbl). Retarding the ignition timing acts in a direction that promotes a drop in engine rotation, resulting in a further drop in engine rotation speed.

As the idle operating state approaches, the parameter (Ii!A/N) approaches the predetermined value, and eventually becomes less than the predetermined value, and the ventilation valve is closed, blocking air from flowing into the engine via the ventilation passage. At the same time, the valve opening degree of the ISC valve is fed, for example, from time t4 in FIG. Since bank control is performed, the engine speed will eventually reach the target idle speed due to this feedback control, but if the above-mentioned increase or drop in the engine speed is large, a hunting phenomenon will occur.

The present invention has been made to solve such problems, and it is possible to prevent the engine speed from rising or falling immediately after the engine starts, and furthermore from hunting, and to quickly increase the engine speed to the target eye 1' after starting the engine. An object of the present invention is to provide a method for controlling the ventilation tank of a supercharger so that the rotational speed is statically fixed at a certain rotation speed.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a rotor that is disposed in the middle of an intake passage of an internal combustion engine and is rotatably supported by a housing via a bearing. and is formed by the end face of the rotor and the inner circumferential surface of the housing, and is provided with a hench lane passage that communicates the clearance space near the bearing with the atmosphere, and the clearance space is changed depending on the operating state of the internal combustion engine. In the penderation control method for a supercharger, which communicates with the atmosphere and balances the pressure inside and outside the housing of the bearing part, a starting state of the engine is detected, and when the engine is in the starting state, the Hendery silane passage is closed. There is provided a ventilation control method for a supercharger, characterized in that the clearance space is shut off from the atmosphere by using a ventilator.

(Function) When the engine is in a starting state, if the ventilation passage is closed to shut off the clearance space and the atmosphere without determining whether the parameter value A/N is less than or equal to a predetermined value, Air is prevented from being supplied to the engine via the ventilation passage, and a situation in which an excessive amount of air is taken into the engine in the starting state is avoided.

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

FIG. 1 shows a control device for an internal combustion engine that implements the method of the present invention, and reference numeral 10 in the figure indicates, for example, a four-cylinder 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 IA taken into the engine 10 is disposed. The electronic control unit (ECU) 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 bypass passage 17 that bypasses the throttle valve 15 is connected to the intake pipe 12. One end of the bypass passage 17 is connected to the intake air upstream of the throttle valve 15 and downstream of the air flow sensor 14. The other end of the pipe 2 communicates with an intake pipe 12 downstream of a throttle valve 15 and upstream of a supercharger 16, which will be described later. An idle speed control valve (ISO valve) 18 is disposed in the middle of the bypass passage 17. This ISC valve 18
consists of a valve body 18a that opens and closes the bypass passage 17, and a pulse motor 18b that is connected to the valve body 18a and controls the valve opening degree.The pulse motor 18b is electrically connected to the output side of the electronic control unit 20. connected to
The valve opening degree of the valve body 18a is controlled according to the number of pulses of the drive pulse signal supplied from the electronic control unit 20. By opening and closing the ISC pulp 18, the amount of air passing through the bypass passage 17 and bypassing the throttle valve 15 is increased or decreased, thereby statically fixing the idle speed of the engine 10 to the target idle speed.

A supercharger 16 is disposed in the intake pipe 12 between the throttle valve 12 and the engine 10.

The supercharger 16 is a Roots-type supercharger mechanically driven by the engine 10, and its connection to the engine 10 is controlled by an electromagnetic clutch (not shown). Two dual-type rotors 16b are fitted into the housing 16a of the supercharger 16 so that they can rotate in synchronization in opposite directions while meshing with each other, and the rotor shafts f6c of these rotors 16b are connected to the housing through bearings (not shown). 1
．． 6a. A slight clearance space is formed between the inner peripheral surface of the housing 16a and the end surface of the rotor 16b, and a passageway (ventilation passageway) 16d communicating with the vicinity of the bearing in the clearance space is formed. is connected to one end of a conduit (ventilation control passage) 28 via a bow 16e provided in the housing 16a. The other end of the pipe line 28 is connected to a boat 12a provided in the intake pipe 12 upstream of the throttle valve 15 and downstream of the air flow sensor 14. A Ti magnetic valve (ventilation valve) 29 is disposed in the middle of the pipe line 28, and the ventilation valve 29 includes a valve body 29a that opens and closes the pipe line 2B, and a valve body 29a that opens and extinguishes when energized. The electromagnetic solenoid 29b is connected to the output side of the electronic control unit 20 and is controlled to open by an on/off signal from the electronic control unit 20. The supercharger 16 is activated by the on operation (engagement) of the electromagnetic clutch and supplies pressurized air to the engine 10.

An ignition plug 26 is attached to each cylinder 10a of the engine 10, and the ignition plug 26 is connected to the output side of the electronic control unit 20 via a distributor 24 and an evening knife device 22. The Eve knife device 22 generates a secondary high voltage using an ignition coil (not shown) based on an ignition control signal from the electronic control unit 20, and this high voltage is supplied to the distributor 24.
The fuel is sequentially supplied to the spark plugs 26 of each cylinder in a predetermined order to ignite the air-fuel mixture in the cylinder 10a. The electronic control unit 20 calculates the optimum ignition timing according to the operating state of the engine 1o and outputs the ignition control signal, while retarding the ignition timing when the engine speed is higher than the target idle speed during idling operation, If it is low, the engine speed is controlled so that the engine speed is statically fixed at the target idle speed by advancing the engine speed.

On the input side of the electronic control unit 20, there are various sensors such as an idle switch 30 that detects the fully closed position of the throttle valve 15, an engine rotation speed sensor 31 that is attached to a camshaft (not shown) and detects the engine rotation speed, A starter switch that operates a starter motor (not shown).

Starter switch sensors 32 and the like that detect the on/off state of keys (key switches) are connected to each other, and these sensors supply detection signals to the electronic control unit 20.

Next, the operation of the control device configured as described above will be explained with reference to FIG.

First, the electronic control unit 20 determines whether the engine 10 is starting (cranking 4 or not) (step 41).This starting determination is performed when, for example, the starter switch sensor 32 indicates that a scooter (not shown) is in an on state.
Further, the determination is made based on whether the engine rotation speed detected by the engine rotation speed sensor 3I is equal to or lower than a predetermined rotation speed (for example, 450 rpm). This determination result is positive (Ye
s), the electronic control unit 20 does not output an energizing signal to the hennulation valve 29, closes it, and converts the clearance space from the intake air W-]2 (atmosphere) on the upstream side of the throttle valve 15. Shut off (step 44
), the pressure in the clearance space near the bearing of the supercharger 16 immediately after starting the engine 10 is not significantly different from atmospheric pressure, and there is no fear of grease or the like flowing out.On the other hand, by closing the hennulation valve 29,
It is possible to bypass the throttle valve I5 and prevent air from flowing into the engine 10 via the ventilation passage (pipe line 28 and passage 16d) and the clearance space.

If the determination result in step 41 is negative (NO), that is,
If the above-mentioned start-up determination condition is not satisfied and the engine 10 is not started, the electronic control unit 20 determines when the engine 10 reaches the above-described cranking state (when the start-up determination in step 41 is first determined to be negative). ), it is determined whether a predetermined time (for example, 55 ec) has elapsed (step 42), and if the predetermined time has not elapsed, it is determined that the engine 10 is still in the starting state and step 44 is executed. , closes the pen narration valve 29. At the time of starting the engine 10 and immediately after starting, the engine speed is statically fixed to the target idle speed by the ISC valve 18, and the engine speed is controlled by conventionally known ISC control and ignition timing control. By unconditionally closing the hennulation valve 29 for a period sufficient for the engine speed to stabilize, the engine speed increases during this period,
Subsequent depression can be prevented.

When the predetermined time has elapsed and the determination result in step 42 becomes affirmative, the electronic control unit 20 controls the engine I.
It is determined whether or not the engine is being operated in a predetermined low-load operation H range such as idling (step 43). This determination is made, for example, by determining whether the parameter value A/N calculated from the intake air IA detected by the air flow sensor 14 and the engine rotation speed N detected by the engine rotation speed sensor 31 is less than or equal to a predetermined value. .

When the engine IO is operated in a low load operating range such as idling (if the determination result in step 43 is affirmative),
After performing step 44, the hennulation valve 2 is
9 remains closed. In this way, during low load operation such as idling when the throttle valve 15 is fully closed, the hench race three passageway (pipe line 28 and passageway 16d)
This eliminates the inconvenience that air is supplied to the engine 10 through the air and the engine speed increases.

On the other hand, if the determination result in step 43 is negative, the process proceeds to step 45, where the electronic control unit 20 outputs an energizing signal to the hennulation valve 29 to open it. At this time, the clearance space near the bearing between the rotor 16b and the housing 16a is communicated with the atmosphere through the pipe line 28 and the passage 16d, and the differential pressure before and after the bearing can be maintained at a small value. This prevents lubricating oil such as grease from flowing out.

(Effects of the Invention) As detailed above, according to the supercharger hennulation control method of the present invention, when the engine is in the starting state, the hennulation passage is closed and the rotor end face and the inner periphery of the housing are closed. Since the clearance space near the bearing that supports the rotor is blocked from the atmosphere, air is blocked from flowing into the engine through the ventilation passage, and air is not supplied to the engine immediately after the engine starts. This prevents the intake air amount from increasing unnecessarily, and prevents the occurrence of hunting due to a jump in engine speed and a subsequent drop in engine speed.

[Brief explanation of the drawing]

The drawings show an embodiment of the invention, and FIG. 1 shows a control of an internal combustion engine implementing the method of the invention. 11 is a block diagram showing the overall configuration of the device, FIG. 2 is a flowchart showing the ventilation control procedure of the supercharger, which is executed by the electronic control unit 20 shown in FIG. 1 immediately after engine startup, and FIG. 3 is a conventional 2 is a timing chart showing the valve opening degree of an ISC valve (bypass valve), ignition timing, and changes over time in the engine speed for explaining the hunting phenomenon of the engine speed that occurs when the engine is started by the ventilation control method of FIG. lO... Internal combustion engine, 12... Intake passage, 16.
...Supercharger (supercharger), 16a...Housing, 16b...Rotor, 16d...Passage (Henderesion i [3), 18...ISC valve (bypass valve), 20...・Electronic control unit, 22... Igniter device, 26... Spark plug, 28
. . . Pipe line (Henderajon connection i), 29 . . Ventilation valve, 31 . . . Engine speed sensor, 32 . . . Starter switch sensor. Applicant Mitsubishi Motors Corporation Mitsubishi Electric Corporation Agent Patent Attorney Kan Nagato Figure 3 B Guma

Claims (2)

[Claims] (1) A rotor is disposed in the intake passage of an internal combustion engine and is rotatably supported by a housing via a bearing, and a clearance is formed between the end face of the rotor and the inner circumferential surface of the housing, and a clearance near the bearing is provided. A ventilation control method for a supercharger, wherein a ventilation passage communicating a space with the atmosphere is provided, the clearance space is communicated with the atmosphere according to the operating state of the internal combustion engine, and internal and external pressures of the housing of the bearing portion are balanced. . A method for controlling ventilation of a supercharger, comprising detecting a starting state of an engine, and closing the ventilation passage to shut off the clearance space from the atmosphere when the engine is in the starting state. (2) The supercharger according to claim 1, wherein it is determined that the internal combustion engine is in the starting state until a predetermined period has elapsed from the time when the internal combustion engine exits the cranking state. ventilation control method.