JPS595845A - Method of controlling restriction of intake air of diesel engine - Google Patents

Abstract

PURPOSE:To prevent the generation of white smoke due to excessive restriction of intake air, by controlling the opening of a main intake throttle valve of a Diesel engine according to the depth of depression of an accelerator pedal, and fully closing a subsidiary throttle valve provided in a passage by-passing the main throttle valve. CONSTITUTION:A main throttle valve 4 is provided in a main intake passage 3 of a Diesel engine 1 and a subsidiary throttle valve 6 is provided in a subsidiary intake passage 5 by-passing the main throttle valve 4. The main throttle valve 4 is controlled such that its opening is increased with increasing of the depth of depression of an accelerator pedal 8 while the opening of the subsidiary throttle valve 6 is controlled by switching vacuum-operated change-over valves 13, 14 by means of a control unit 20 to which output signals of various sensors 21-24 are applied. At the time of idling operation, intake-air flow is restricted by keeping the subsidiary throttle valve 6 at its medium opening for reducing vibration and noises produced by the engine, while it is fully opened at the time of deceleration. Therefore, even if the main throttle valve is closed completely, excessive restriction of intake air is avoided, so that production of white smoke can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake throttle control method for a diesel engine used in a vehicle such as an automobile.

Diesel engines are generally controlled by controlling the fuel supply amount without controlling the intake air pressure. When the amount of air is controlled, the compression ratio is reduced, thereby reducing engine vibration and engine ll! It has been known for some time that sound can be reduced. Particularly during idling operation when the amount of intake air can be greatly restricted, if appropriate intake throttling is performed, engine vibration and engine noise can be significantly reduced without impeding engine drivability.

However, when the intake air is throttled excessively, incomplete combustion occurs due to an excessive decrease in the compression ratio due to a decrease in intake pipe pressure, and white smoke is generated. In particular, in order to prevent a sudden drop in engine speed when restarting fuel injection after racing, when resuming fuel cut during deceleration, or during sudden acceleration or deceleration after deceleration driving, the fuel If the intake throttle is being throttled at the same intake throttle level as during idling when injection is performed, the intake pipe pressure will be extremely low and white smoke will be generated due to incomplete combustion. In addition, if intake throttling is performed as described above when fuel is injected during deceleration operation due to fuel fit 1+31 sword pump, changes in the fuel injection nozzle over time, variations in fuel amount control of the fuel injection pump, and fuel temperature, white smoke may occur. occurs. The generation of this white smoke causes a strange odor and is not a good idea in terms of exhaust gas purification measures.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new intake throttle control method that reduces engine vibration and noise, particularly during idling operation, and avoids the generation of white smoke due to excessive intake throttle.

According to the present invention, the present invention provides a vehicle diesel engine that has a main intake throttle valve in the middle of a main intake passage and a sub-intake throttle valve in the middle of a sub-intake passage that is provided to bypass the main intake throttle valve. In the intake throttle control method for a gas engine, the main intake throttle valve is fully opened when the accelerator pedal is not depressed, and the opening degree of the main intake throttle valve is increased in accordance with an increase in the amount of depression of the accelerator pedal. This is achieved by an intake throttle control method in which the auxiliary intake throttle valve is set to a predetermined intermediate opening degree during idling operation, and the auxiliary intake throttle valve is fully opened during deceleration operation.

According to the intake throttle control method according to the present invention, the main intake throttle valve is fully closed during idle operation, and the auxiliary intake throttle valve is located at a predetermined intermediate opening position, so that appropriate intake throttle can be performed during idle operation. It is possible to reduce engine vibration and engine lA@ during idling operation. During deceleration driving, the main intake throttle valve fully closes when the accelerator pedal is released, but at this time, the auxiliary intake throttle valve opens fully, thereby avoiding excessive intake throttle, and resulting in a significant increase in intake pipe pressure. The drop is prevented and the generation of white smoke is avoided.

The invention will now be described in detail by way of example embodiments with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine implementing the intake throttle control method according to the present invention. In the figure, numeral 1 indicates a diesel engine, and the diesel engine takes in air through an intake pipe 2.

The intake pipe 2 constitutes a main intake passage 3, and a main intake throttle valve 4 is provided in the middle of the main intake passage. Further, the intake pipe 2 constitutes a sub-intake passage 5 that bypasses the main intake throttle valve 4. This sub-intake passage 5 is narrower than the main intake passage 2, and a sub-intake throttle valve 6 is provided in the middle thereof.

The main intake throttle valve 4 is mechanically connected to the accelerator pedal 8 by a common accelerator linkage 7, and when the accelerator pedal 8 is not depressed, it is in the fully open position as shown in the figure. The opening degree is increased in accordance with the increase in the amount of depression.

The auxiliary intake throttle valve 6 is connected to a diaphragm device 10 by a drive lever 9, and its two diaphragm chambers 11.1
When negative pressure is not introduced into any of the diaphragm chambers 12, it is in the fully open position as shown in the figure, and when negative pressure is introduced only into the diaphragm chamber 12, it is in the predetermined intermediate open position as shown by the broken line in the figure. Located in the diaphragm chamber 11.1
When oral pressure is introduced into either of the openings 2, the openings are in the fully open position.

The diaphragm chambers 11 and 12 are each equipped with a negative pressure switching valve (VS
The negative pressure generated by the negative pressure pump 15 and atmospheric pressure are individually and selectively supplied by the negative pressure switching valve (VSV2) 14 and the negative pressure switching valve (VSV2) 14. Negative pressure switching valve 13
．． 14 are both configured as electromagnetic valves, and when energized, the negative pressure of the negative pressure pump 15 is supplied to the diaphragm chamber, and when not energized, atmospheric pressure is supplied to the diaphragm chamber.The energization control for these negative pressure switching valves is as follows. This is performed by a control device 20, which will be described later.

A fuel injection nozzle 16 is attached to the diesel engine 1, and a fuel injection pump 1 is attached to the fuel injection nozzle 16.
7, high pressure fuel is supplied. The fuel injection pump 17 is an electrically controlled fuel injection pump, and is given a fuel injection amount signal Fv, a fuel injection timing signal Ft, and a fuel supply stop signal FC from the control device 2o, and based on these signals, it controls the fuel injection amount, It controls fuel injection timing and also stops fuel supply.

The control device 20 includes a general microcomputer including a CPU, RAM, ROM, etc., and an intake pressure sensor 2.
1, the engine speed of the diesel engine 1IIrIA1 detected by the speed sensor 22, and the amount of depression of the accelerator pedal 8 detected by the accelerator sensor 23. A fuel supply stop signal Fv, a fuel injection timing signal [t, and a fuel supply stop signal Fc are output.

In this specification, only the fuel control when the accelerator pedal 8 is not depressed, which is related to the non-invention method, will be explained. When the accelerator pedal 8 is not depressed and the engine speed is above a predetermined value, the fuel injection amount becomes zero and no fuel injection is performed, and fuel injection is performed only when the engine speed is below a predetermined value. Furthermore, when the rate of decrease in engine speed is equal to or higher than a predetermined value, a dashpot effect occurs and fuel injection is performed to prevent engine stall due to a sudden drop in engine speed.

1liI71tll installation fif20 is connected to the negative pressure switching valve 13.14 according to
Controls energization to. This implements the intake throttle control method according to the present invention.

Next, the manner in which the intake throttle control method according to the present invention is carried out will be explained with reference to the flowchart shown in FIG.

First, in step 1, it is determined whether the vehicle speed is zero or not. If the vehicle speed is not zero, proceed to step 2,
If the vehicle speed is zero, proceed to step 4.

In step 2, the rate of change ΔA of the accelerator pedal depression rate Acap detected by the accelerator sensor 23 is
A determination is made as to whether ccp is smaller than zero. ΔA
When ccp is less than zero, it means that the amount of depression of the accelerator pedal 8 is being reduced, and in this case, the process proceeds to step 3; otherwise, the process proceeds to step 4.

In step 3, it is determined whether the depression rate ACCI) of the accelerator pedal 8 detected by the accelerator sensor 23 is less than a predetermined value, for example 10%. When the depression rate is 10% or less, the process proceeds to step 5; otherwise, the process proceeds to step 4.

In step 5, control is performed to set FLAG to 1. When the process advances to step 5 after passing through steps 1 to 3, the diesel engine 1 is being operated at a reduced speed.

In step 4, it is determined whether or not the dashpot is in operation. Dashpot] - If the dashpot is in effect, proceed to step 5; if the dashpot is not in effect, proceed to step 6.

In step 6, it is determined whether the engine rotation speed Ne detected by the rotation speed sensor 24 is less than or equal to a predetermined value, for example, 90Q rpm. psJe・' 900
rl) If Ill, proceed to step 8, otherwise proceed to step 7.

In step 7, the engine speed is set to a predetermined value, for example 20.
00 rl) Ill or less is determined. At this time, if Ne≦20 Orpm is not satisfied, the process proceeds to step 10, and in step 10, control is performed to set FLAG to O. At this time, the diesel engine 1 is being operated at high speed.

On the other hand, when Ns≦2000 rpWI, the process advances to step 9, and in step 9, control is performed to set FLAG to 1.

In step 6, if Ne<900 rpm-, the process advances to step 8, and in this step, it is determined whether the accelerator pedal depression rate Accp is smaller than 4%. When Accp<4%, the process proceeds to step 11. At this time, the diesel engine 1 is in idle operation, and in step 11, the FLAG
Control is performed to set the value to 0.

Steps 5.9.10.11 are each FLAG control steps, and next to these steps proceed to step 12. In step 12, it is determined whether the key is off. When the key is off, that is, when the engine is stopped, both negative pressure switching valves 13.1/l are energized, and negative pressure is introduced into both diaphragm chambers 11.12. At this time, the sub-intake throttle valve 6 is fully closed. At this time, unless the accelerator pedal 9 is depressed to stop the operation of the diesel engine 1, the main intake throttle valve 4 is also in the fully closed position.
Substantially no air is supplied to the diesel engine 1, whereby operation of the diesel engine 1 is stopped prior to stopping the fuel supply.

In step 12, when the key A is 4T, the process advances to step 13, and in this step, it is determined whether FL8 is 1 or not. Proceeding to step 15, in this step, both negative pressure switching valves 13.1/l are not energized.Therefore, in step 1), the auxiliary intake throttle valve 6 is brought to the fully open position. If FLAG = 1, the process proceeds to step 1G, in which only the electromagnetic switching valve 14 is energized,
Negative pressure is supplied only to the die 17 and flamm chamber 12, and the sub-intake throttle valve 6 is opened at the intermediate opening position. Above) By being controlled like a flea, the auxiliary intake throttle valve 6 is operated during deceleration, when the dashpot is activated, and when the engine speed is between 900 and 200 Qr.
pm, it is fully open, when the engine is idling and the engine speed is 2000 rl1m or more, it is in the middle, and when the engine is stopped, it is fully open. Even if the accelerator pedal 9 is released during deceleration driving and the main intake throttle valve 4 is at the fully open position, the sub intake throttle valve 6 is fully open at this time, so the excessive intake throttle valve 1j This prevents the occurrence of white smoke.Furthermore, even if fuel II injection is performed when deceleration operation shifts to acceleration operation, the auxiliary intake throttle valve 6 is already fully open during deceleration driving, and the intake air Since an excessive drop in pipe pressure is prevented, incomplete combustion of the fuel is prevented at this time, and the generation of white smoke is prevented.In general, a delay time is set for the switching operation of the auxiliary intake throttle valve. It is a good idea to hold the J sub-intake throttle valve in the switching position (1 below the previous row) for a certain period of time even if the operating conditions change, and then move it to the switching position that meets the new regulations. This is to prevent the opening degree of the auxiliary intake throttle valve from changing frequently due to condition changes fa.It is also an effective method to provide hysteresis in the condition setting.Also, the delay time as described above is By providing this, an increase in intake pipe pressure can be effectively prevented even when deceleration operation and acceleration operation are performed alternately, and generation of white smoke can be more effectively prevented.

In addition, the sub-intake throttle valve 6 is used when the engine speed is 900 to 200O.
Since it is fully opened when the rpm is high, the accelerator pedal does not have to be depressed very much, and even when the opening of the main intake throttle valve 4 is small, fuel can be injected without producing white smoke or reducing fuel efficiency. It becomes possible to increase ω.

It should be noted that setting the intake throttle valve 6 to the intermediate position when the engine speed is 200 rpm will prevent malfunction of the injection pump and prevent A-balun of the diesel engine due to an increase in the amount of fuel. , prevents a sudden increase in engine speed due to malfunction of the accelerator sensor. In other words, if the main intake throttle valve 4 is fully open and the auxiliary intake throttle valve is in the middle, a sufficient amount of intake air will not be available even if the fuel intake increases, so the accelerator pedal must be released. This can prevent the A level run of the Deep Pill engine.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of a diesel engine implementing the intake throttle control method according to the present invention, and FIG. 2 is a flowchart showing an implementation outline of the intake throttle control method according to the present invention. It is.

Claims (1)

[Claims] An intake throttle control method for a diesel engine for a vehicle, in which a main intake throttle valve is provided in the middle of a main intake passage for a vehicle, and the sub-intake throttle valve is placed in the middle of a sub-intake passage provided by bypassing the main intake throttle valve. When the accelerator pedal is not depressed, the main intake throttle valve is fully opened, and the opening degree of the main intake throttle valve is increased in accordance with the increase in the amount of depression of the accelerator pedal.During idle operation, the main intake throttle valve is fully opened. An intake throttle control method that sets a throttle valve to a predetermined intermediate opening degree and fully opens the auxiliary intake throttle valve during deceleration operation.