JPH0345232B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glow control method and apparatus for a diesel engine, which aims to prevent the generation of white smoke during deceleration of a diesel engine equipped with an intake throttle system.

In a vehicle equipped with a diesel engine, when the accelerator is fully closed during deceleration, the amount of fuel decreases compared to the amount of air, increasing fuel efficiency and increasing explosion pressure. This causes engine vibration and exhaust pipe vibration, resulting in muffled noise. This muffled sound is particularly disliked in passenger cars.

Therefore, intake throttling systems have been proposed to suppress muffled noise. That is, the intake air is throttled at the same time as the start of deceleration to lower fuel efficiency, resulting in incomplete combustion and suppressing muffled noise.

However, with the conventional intake throttling system to prevent muffled noise, if the intake throttling is performed when the engine speed is in the medium to high speed range, the intake negative pressure becomes too large and white smoke emissions due to incomplete combustion increase. There is a fear.

An object of the present invention is to provide a glow control method and device for a diesel engine that suppresses the generation of white smoke when air intake is throttled.

In order to achieve the above object, the present invention determines engine deceleration based on the accelerator opening state, intake negative pressure, and engine speed, and when the deceleration state is determined, energizes the glow lamp to compensate for incomplete combustion. This prevents the generation of white smoke by burning.

FIG. 1 is a block diagram showing one embodiment of the present invention.

A throttle valve 2 for throttling the intake air is provided in the intake pipe 1, and the throttle valve 2 is driven by a step motor 3. Further, a port 4 for negative pressure detection is provided in the intake pipe 1 on the downstream side of the throttle valve 2. Furthermore, the glow plug 5 has been conventionally provided in diesel engines, and is used, as is well known, when starting the engine in a cooled state. The glow control device generates the glow plug energization command according to the present invention and controls the step motor 3 using the output signals of the sensor and the switch as an information source.
It is comprised of an electronic control circuit (ECU) 6 that executes various controls including engine control, and a glow control circuit 7 that energizes the glow plug 5 in response to an energization command from the ECU 6. The sensors include a negative pressure sensor 8 that detects the negative pressure of the port 4, a rotation sensor 9 that detects the engine speed, and an accelerator switch 10 that detects the fully closed state of the accelerator.
As the ECU 6, a microcomputer is most suitable.

In the above configuration, the accelerator switch 10
The rotation sensor 9 detects that the OFF state is detected and the engine speed is higher than the set speed (for example, 800 rpm), and the negative pressure sensor 8 detects that the intake negative pressure is higher than the set value (for example, 150 mmHg). When these three conditions are met, the ECU 6 determines the deceleration state, and the ROM in the ECU 6
The step motor 3 is driven according to a preset map, the throttle valve 2 is closed, and the intake negative pressure is controlled to prevent muffled noise from occurring. at the same time,
In order to suppress white smoke, the ECU 6 issues an energization command to the glow control circuit 7 to energize the glow plug 5. Note that if the above-described determination of the deceleration state is not established, other processing is executed.

An example of the above processing by ECU6 is shown below.
This is a flowchart of FIG. 2.

FIG. 3 is a block diagram showing a second embodiment of the invention. In this embodiment, the throttle valve 2 is driven by a diaphragm. A dart pot 11 is connected to the throttle valve 2 to suppress sudden changes, and the throttle valve 2 can also be driven by an accelerator pedal 12. The diaphragm 13 connected to the throttle valve 2 is controlled by a drive system 14 that is different from the control system by the ECU 6.
Therefore, the processing of this embodiment is obtained by removing the step motor drive processing from the processing flow shown in FIG. The configuration and process for energizing the glow plug are the same as those shown in FIG. 1, so a description thereof will be omitted. The effects of this embodiment are similar to those of the embodiment shown in FIG.

FIG. 4 is a block diagram showing a third embodiment of the present invention. In this embodiment, in order to further improve the prevention of incomplete combustion, in addition to the conventional glow plug for starting aid, a second glow plug dedicated to preventing white smoke is provided. In Figure 4,
Components that are the same as those shown in FIGS. 1 and 3 are designated by the same reference numerals. A swirl chamber 21 is provided in the upper part of the main chamber 20 of the engine via a passage, and in the swirl chamber 21, in addition to the glow plug 5, a glow plug 22 for preventing white smoke according to the present invention is provided.
and a nozzle 23 through which fuel is injected.
The glow plug 5 is energized by the energizing circuit 24 in cold or cold weather, and has the function of warming the swirl chamber and facilitating ignition.

On the other hand, the energization of the glow plug 22 is controlled by the glow control circuit 7, and the energization conditions are as described in the first embodiment, so the explanation will be omitted. In order to improve the ignition performance in the situation of deceleration during high rotation, the glow plug 22 is designed to consume power of, for example, 12 (V) x 10 (A) = 120 (W) or more per plug. Turn on the power and keep the plug surface temperature between 1000℃ and 1200℃.

According to this embodiment, since the second glow plug is energized only during deceleration, the life of the plug can be extended and reliability can be improved.

As is clear from the above, according to the present invention, it is possible to suppress the generation of white smoke during deceleration of a diesel engine that is equipped with an intake throttle device and supplies fuel during deceleration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a flowchart showing an example of processing in the embodiment of FIG. 1, FIG. 3 is a block diagram showing a second embodiment of the invention, and FIG. 4 shows a third embodiment of the invention. It is a block diagram. 1...Intake pipe, 2...Throttle valve, 3...
...Step motor, 4...Port, 5, 22...
Glow plug, 6... Electronic control circuit, 7... Glow control circuit, 8... Negative pressure sensor, 9... Rotation sensor, 10... Accelerator switch, 24... Energizing circuit.

Claims (1)

[Scope of Claims] 1. In a diesel engine system equipped with an intake throttle and in which fuel is supplied even during deceleration, when the intake negative pressure is above a predetermined value, the engine speed is above a predetermined value which is somewhat higher than the idling speed, and when the accelerator is A glow control method for a diesel engine, characterized in that a deceleration state is determined based on whether the engine is in a fully closed state, and a glow plug is turned on. 2. In a diesel engine that is equipped with an intake throttle and is supplied with fuel even during deceleration, there is a negative pressure sensor that detects the negative pressure in the intake pipe, a rotation sensor that detects the engine speed, and a sensor that operates in conjunction with accelerator operation. an accelerator switch that outputs an output signal when the accelerator is fully closed; and an accelerator switch that outputs an output signal when the accelerator is fully closed; an electronic control circuit that determines the deceleration state and outputs an energization command based on the fact that the value is greater than or equal to the value and that an output signal is issued from the accelerator switch; 1. A glow control device for a diesel engine, comprising a glow control circuit that energizes. 3. The glow control device for a diesel engine according to claim 2, wherein the glow plug is also used for starting in cold weather. 4. The glow control device for a diesel engine according to claim 2, wherein the glow plug is a second glow plug dedicated to deceleration, which is different from a plug for starting in cold weather.