JPH0710035Y2 - White smoke reduction device for diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a white smoke reducing device for a diesel engine capable of automatically reducing the amount of white smoke emitted during warm-up of the diesel engine.

(Prior Art) When a diesel engine is warmed up after cold start, unburned gas is emitted as white smoke. White smoke at that time is initially discharged at a low engine speed, and is discharged in large amounts when the water temperature of the engine cooling water is lower than a predetermined temperature (T ₁ is set), the engine speed becomes high, and the fuel its emissions as the water temperature of the engine coolant is higher than a predetermined temperature (referred to as T ₂₎ proceeds the combustion follows a discharge situation reduced.

By the way, the exhaust gas of an engine contains a large amount of carbon fine particles (particulates). Therefore,
In order to suppress the release of the particulates as much as possible and to conserve the environment, an exhaust gas aftertreatment device is installed in the middle of the exhaust path from the engine.

As such a device, an electric heater regenerating type particulate trap is known. This device has a structure in which, for example, a filter having a honeycomb structure carrying a combustion catalyst is housed in a cylindrical container, and an electric heater is arranged on the upstream side thereof.

The exhaust gas that has flowed into the trap passes through the filter and flows out from the trap. In the process, particulates in the exhaust gas are captured by the filter and are deposited on the filter. If this amount of accumulation increases, the filter will become clogged and pressure loss will increase, so at an appropriate time, the electric heater is energized to operate, and the radiant heat burns away the accumulated particulates to remove the filter. Is playing.

(Problems to be solved by the invention) However, the above-mentioned electric heater regeneration particulate trap can capture particulates that are fine particles, but captures white smoke generated during warm-up after the above-described low temperature start. It is not possible. This is because this white smoke is unburned gas.

The present invention aims to provide a device for reducing white smoke from a diesel engine by utilizing an electric heater incorporated in the trap.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the present invention, an electric heater regenerative particulate trap installed in an exhaust passage of a diesel engine is provided with an engine for the electric heater. During warm-up, the electric heater operation is turned on when the water temperature of the engine cooling water is lower than the first predetermined temperature, and the electric heater is turned on when the water temperature is higher than the second predetermined temperature which is higher than the first predetermined temperature. A white smoke reducing device for a diesel engine is provided, which is equipped with control means for turning off the operation and operating an electric heater when the engine is warmed up after a cold start to burn unburned gas. It

(Operation) When the engine is started and enters the warm-up process, the power supply from the battery to the starter is turned off by the command from the control means, and at the same time, the water temperature signal of the engine cooling water is input to the control means, and the water temperature is set to the predetermined value described above. When the temperature is lower than T ₁ , the electric heater is turned on by a command to the electric heater. Therefore, of the exhaust gas from the engine, unburned gas that becomes white smoke is heated by the electric heater and burned. As a result, white smoke emissions are reduced.

Although the water temperature of the engine cooling water is not discharged white smoke reaches a T _2, a command off the electric heater is issued from the control means for the water temperature signal is inputted at that time, energization of the electric heater is stopped .

In this way, when warming up the engine after the engine is started at a low temperature, the electric heater incorporated in the trap operates to detect unburned gas by the control means that detects the water temperature of the engine cooling water and operates by the water temperature signal. Since it burns, white smoke emission during warm-up is reduced.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings. In the apparatus schematic diagram of FIG. 1, the particulate trap 1 is attached in the middle of an exhaust passage 4 between a diesel engine 2 and a muffler 3. A filter 5 is housed in the particulate trap 1, and an electric heater 6 is arranged in front of the filter 5. The electric heater 6 is connected to the control means 8 via the switch 7.

A starter switch 9 for detecting the operating state of the starter is attached to the input side of the control means 8. When a starter ON signal is input from the starter switch 9, the switch 7 is switched.
And a command to turn off the electric power to the electric heater 6 is issued.

Further, the engine speed (Ne) is provided on the input side of the control means 8.
The sensor 10 is installed and the engine speed is the specified speed.
When it becomes higher than Nx, switch 7 is opened and electric heater 6
It is designed to issue a command to turn off power to the.

Further, a water temperature sensor 11 for detecting the water temperature of the engine cooling water is attached to the input side of the control means 8.

Next, the operation will be described with reference to FIG.

First, insert the engine key and start the starter. In response to the ON signal from the starter switch 9, the control means 8 opens the switch 7 and issues a command to turn off the power supply to the electric heater 6. At this time, the flag value FLG which is a program control variable is set to 0. When the starter operates, the electric heater 6 is turned off to secure the battery capacity and the cranking rotation speed at the time of starting.

When the start signal of the engine is completed and the engine is warmed up in response to the OFF signal from the starter switch 9, the control means 8 simultaneously receives the water temperature signal of the engine cooling water from the water temperature sensor 11. When the water temperature at this time is higher than the second predetermined temperature T ₂ as shown in FIG. 3, the control means 8 opens the switch 7 to turn off the operation of the electric heater 6. Also in this case, the flag value FLG is set to 0.

When the water temperature is lower than T ₁ , the flag FLG is set to the value 1, then the engine speed Ne is detected, and when Ne is Nx or more, the switch 7 is opened to turn off the electric heater 6.
When the engine is running at a high speed, the amount of white smoke emitted is small, so it is not necessary to turn on the electric heater 6. On the other hand, when Ne is smaller than Nx, the switch 7 is closed and the electric heater 6 is turned on to generate heat.

When the water temperature is lower than T _{2 and} higher than the first predetermined temperature T ₁ , the engine speed sensor 10 detects the engine speed Ne, and when Ne is higher than Nx, the switch 7 is opened to turn on the electric heater 6. A command to turn off is issued from the control means 8 and Ne
Is smaller than Nx, the control means 8 issues a command to close the switch 7 and turn on the electric heater, and the electric heater 6 generates heat.

At this time, the exhaust gas of the engine 2 is flowing through the exhaust path 4, but when the electric heater 6 is turned on, the unburned gas that becomes white smoke is burned by the electric heater 6, so white smoke is discharged to the downstream side. Will not do.

If the water temperature is lower than T ₁ , as the warm-up time elapses,
As shown in FIG. 3, the temperature of the engine cooling water rises. When the water temperature exceeds the predetermined temperature T ₁ , it is determined whether or not the above-mentioned flag value FLG is set to the value 1. This flag
FLG is set when the water temperature immediately after the engine is started is lower than the predetermined temperature T ₁ , so the flag value FLG is 1
In this case, after determining the engine speed, the electric heater is kept turned on. And
When the water temperature becomes higher than the second predetermined temperature T ₂ and the warm-up ends, the flag value FLG is reset to 0, and then the switch 7
Is closed to stop energizing the electric heater 6.

When the water temperature immediately after the engine is started has already exceeded the predetermined temperature T ₁ , the flag value is not set to value 1. Therefore, even if the water temperature is lower than the predetermined temperature T ₂ , the electric heater 6 remains off. Left unattended.

(Effects of the Invention) As is clear from the above description, the white smoke reduction device for a diesel engine of the present invention has the configuration of an electric heater regenerating type particulate trap assembled in the exhaust path of the diesel engine, With respect to the electric heater, when the water temperature of the engine cooling water is lower than the first predetermined temperature when the engine is warmed up, the electric heater operation is turned on, and the water temperature is set to the second predetermined temperature higher than the first predetermined temperature. When the temperature is higher, the electric heater operation is turned off, and the control means for burning the unburned gas by operating the electric heater at the time of warm-up after cold start of the engine is attached. Since the unburned gas in the exhaust gas is burned by the electric heater that generates heat, the emission of white smoke is reduced.

For example, when the electric heater is not operated at all during warm-up, white smoke is emitted for a long time as shown by the solid line in FIG. 4, but in the case of the device of the present invention, it is shown by the dotted line. As described above, the emission of white smoke stops within a short time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing the routine operation of the embodiment device, FIG. 3 is a graph showing an example of the temperature rise of engine cooling water during warm-up,
FIG. 4 is a graph showing the relationship between the amount of white smoke and the warm-up time. DESCRIPTION OF SYMBOLS 1 ... Particulate trap, 2 ... Diesel engine, 3 ... Muffler, 4 ... Exhaust path, 5 ... Filter, 6 ... Electric heater, 7 ... Switch, 8 ... Control means, 9 ... Starter switch, 10 ... Engine speed sensor, 11 ... Water temperature sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-107014 (JP, A) Actual development 57-123911 (JP, U) Actual public 62-8325 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. An electric heater regenerative particulate trap installed in an exhaust path of a diesel engine, wherein the electric heater is connected to the electric heater when warming up the engine.
When the water temperature of the engine cooling water is lower than the first predetermined temperature, the electric heater operation is turned on, and when the water temperature is higher than the second predetermined temperature higher than the first predetermined temperature, the electric heater operation is turned off. A white smoke reducing device for a diesel engine, which is provided with a control means for burning an unburned gas by operating an electric heater when the engine is warmed up after a low temperature start.