JPH0432926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

<Prior art> In internal combustion engines such as diesel engines that have a trap in the exhaust passage to collect particulates such as carbon contained in the exhaust, when the number of exhaust particulates collected by the trap increases, the exhaust pressure rises excessively. However, the engine and emission performance deteriorates, so the traps are regenerated by burning the exhaust particulates collected in the traps at predetermined times. A conventional example of such an exhaust particulate treatment device is shown in FIG.
(See No. 216121).

That is, a honeycomb-shaped trap 4 is housed in a trap case 2 interposed in an exhaust passage 1 of the engine with a buffer material 3 interposed therebetween, and this trap 4 collects particulates in the exhaust gas. This trap 4
A burner device 5 is provided in the upstream exhaust passage 1, and when a predetermined amount of exhaust particulates are collected in the trap 4, the burner device 5 is ignited by a signal from a control device 6, which will be described later, and heats the exhaust particulates. Burn it. The burner device 5 has a large number of exhaust gas introduction holes 7 in the peripheral wall.
a combustion tube 7 with an opening a, a backflow type evaporator tube 8 located inside the combustion tube 7 and having a flame jet hole 8a, and a mixture conduit 9 whose downstream end opening faces into the backflow type evaporator tube 8.
and a glow plug 10 for ignition that faces near the flame jet hole 8a of the reverse flow type evaporator tube 8.

An electromagnetic fuel injection valve 11 is provided at the upstream end of the mixture conduit 9.
An electromagnetic fuel pump 13 is connected from the fuel tank 12 to
Fuel (same as engine fuel, for example, light oil) is introduced. Furthermore, an air supply pipe 16 is connected in the middle of the air-fuel mixture conduit 9, which communicates with a discharge port 14a of an air pump 14 via a diaphragm type three-way valve 15. The pressure chamber of the diaphragm type three-way valve 15 is connected to the electromagnetic type three-way valve 17 in a conductive state.
Negative pressure is supplied through the air pump 14 to introduce discharge air into the mixture conduit 9, while the three-way valve 17
In a non-conducting state, the atmosphere is introduced into the pressure chamber through the three-way valve 17, and the discharged air is discharged to the atmosphere through the three-way valve 15.

The fuel injection valve 11, fuel pump 13, and electromagnetic three-way valve 17 are energized from a battery 18 via an ignition switch 19, and are activated when grounded by a grounding device 20 of the control device 6.

The exhaust inlet side of trap 4 shows the inlet exhaust temperature.
The exhaust temperature sensor 21 that detects T ₁ is the trap 4.
The output voltage of the exhaust temperature sensor 21 is input to the control device 6. Further, a rotation speed sensor 22 for detecting the engine rotation speed and a load sensor 24 such as a potentiometer that rotates in conjunction with the control lever 23a of the fuel injection pump 23 are provided, and these detection signals is input to the control device 6.

Then, the CPU 29 determines whether or not the engine has started based on a signal input from the rotational speed sensor 22 via the F/V converter 25, multiplexer 26, A/D converter 27, and interface PIO 28. When the engine is started, the burner device 5 is activated based on the signal from the load sensor 24.
It is determined whether or not the burner device 5 is operating, and if it is operating, the operation of the burner device 5 is controlled until a predetermined operation is completed.

Furthermore, when the burner device 5 is not in operation, it is determined based on the signal from the exhaust temperature sensor 21 whether the exhaust temperature at the inlet of the trap 4 is a temperature suitable for self-combustion of exhaust particulates (for example, 600° C. or higher). . Then, the exhaust temperature at the entrance of trap 4 is, for example, 600.
When the temperature is above .degree. C., the burner device 5 is deactivated, and the exhaust particulates are heated and burned by the exhaust gas for self-regeneration. When the exhaust temperature is less than 600°C, the trap 4 does not self-regenerate and the exhaust particles are collected in the trap 4, so the exhaust particles are collected per unit time based on the signals from the rotational speed sensor 22 and the load sensor 24. The amount is detected from the memory 30 and integrated. This accumulation of collected amount is reset immediately after the burner device 5 stops operating, and the accumulation of the collected amount is started. When the amount of collected exhaust particulates reaches a predetermined value, it is determined that it is time to regenerate the trap.

When it is determined that it is time to regenerate the trap, the switching circuit 20a of the grounding device 20 is turned on.
After turning on the glow plug relay 31 and preheating the glow plug 21, the switching circuits 20b, 20c, and 20d are turned on. As a result, air is supplied from the air pump 13 to the mixture conduit 9, fuel is supplied from the fuel injection valve 11 to the mixture conduit 9, and the mixture is supplied to the evaporator cylinder 8. Therefore, the air-fuel mixture is ignited and combusted by the glow plug 21, and this combustion gas is mixed with the exhaust gas introduced through the exhaust introduction hole 7a. This high-temperature gas heats and burns the exhaust particulates collected in the trap 4. Note that 32 is a constant voltage generating circuit.

<Problems to be Solved by the Invention> However, in such a conventional exhaust particulate treatment device, the exhaust system including the trap 4 is insufficient immediately after, for example, transitioning from high-speed, high-load operation where the exhaust temperature is high to idle operation. Since it is warmed, vaporization of the air-fuel mixture supplied to the burner device 5 is promoted. Therefore, since the combustion state of the air-fuel mixture is extremely good and the trap 4 is preheated, the temperature inside the trap 4 rises excessively and exceeds the trap failure temperature (approximately 900 degrees Celsius).
There was a risk of damage.

SUMMARY OF THE INVENTION In view of the current situation, it is an object of the present invention to provide an exhaust particulate processing device that can prevent the temperature inside the trap from increasing excessively.

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. An idle rotation speed switching means C is provided that sets the engine idle rotation speed higher when the above exhaust gas temperature is detected than when the engine idle rotation speed is not detected.

<Function> When idle operation is performed with the trap in a high temperature state, the exhaust flow rate is increased by increasing the idle speed, and the increased exhaust flow increases the cooling efficiency of the trap, thereby reducing the temperature inside the trap. The excessive increase in the value was suppressed.

<Example> Examples of the present invention will be described below based on the drawings. Incidentally, the same elements as in the conventional example are given the same reference numerals as in FIG. 4, and the explanation thereof will be omitted.

In the figure, a stopper lever 40 is attached to the support shaft of the control lever 23a of the fuel injection pump 23.
One end is rotatably attached to the stopper lever 40, and the control lever 23a is attached to the stopper lever 40.
The stopper pin 40a abuts against the side wall on the closing side of the
is installed. A shaft 42 of a diaphragm actuator 41 is attached to the other end of the stopper lever 40 so as to be able to swing freely. As will be described later, atmospheric air is introduced into the pressure chamber of the diaphragm actuator 41 when the burner device 5 is not in operation.
Also, the structure is such that negative pressure is introduced during operation. When the burner device 5, which introduces atmospheric air into the pressure chamber, is not in operation, the shaft 42 of the diaphragm actuator 41 is in a fully extended position to the right in FIG.
0, the idle position of the control lever 23a is set to the normal idle rotational speed setting position. Further, when the burner device 5 is in operation, in which negative pressure is introduced into the pressure chamber, the shaft 42 of the diaphragm actuator 41 is retracted to the left in FIG. Set in rotation position.

Switching between introducing the atmosphere and negative pressure into the diaphragm 41 is performed by an electromagnetic three-way valve 43, and when the electromagnetic three-way valve 43 is de-energized, a passage A communicating with the atmosphere is used.
and a passage C that communicates with the pressure chamber of the diaphragm 41, and a passage B and the passage C that communicate with a negative pressure supply source (not shown) such as a vacuum pump when energized.
It is configured to communicate with the

Voltage is applied to the electromagnetic three-way valve 43 from the battery 18 via the ignition switch 19, and when it is grounded by the switching circuit 20e of the grounding device 20 of the control device 6, the electromagnetic three-way valve 43 is energized. be done.

Similarly to the conventional example, the CPU 28 of the control device 6 calculates the amount of collected exhaust particulates, determines the regeneration timing of the trap 4 based on the engine operating state, and controls the fuel injection valve 1.
1. The fuel pump 13, three-way valve 17, and glow plug 21 are energized to operate the burner device 5. Here, the electromagnetic three-way valve 43, the diaphragm 41, and the stopper lever 40 constitute idle rotation speed switching means.

Here, the amount of rotation of the control lever 23a by the stopper lever 40 is preferably such that it increases the normal idle rotational speed (600 to 800 rpm) to 1000 to 1200 rpm.

Further, an outlet-side exhaust gas temperature sensor 44 is provided in the exhaust passage 1 downstream of the trap 4 to detect the exhaust gas temperature at the outlet of the trap 4, and this output voltage is inputted to the control device 6. The control device 6 receives a signal from the temperature sensor 44 when the exhaust gas temperature on the trap outlet side exceeds a predetermined value T ₁ (for example, if the melting limit temperature of the trap 5 is set to 950°C, it is set to 800°C to prevent melting). When the burner device 5 is idle, the electromagnetic three-way valve 43 is energized to raise the idle rotation speed above the normal idle rotation speed, regardless of whether or not the burner device 5 is in operation.

The flowchart shown in FIG. 3 will be explained below.

S1 from rotational speed sensor 22 to F/V converter 2
Voltage V _R input via 5 and load sensor 24
output voltage V _L and output voltage of exhaust temperature sensor 21
Output voltage of VT ₁ and outlet side exhaust temperature sensor 44
Load VT ₂ . Then, it is determined in S2 whether the engine has started or not, and if NO, the process proceeds to S9, where the burner device 5 is deactivated and the process returns to S1. If YES in S2, it is determined in S3 whether or not the exhaust temperature T on the outlet side of trap 4 has exceeded the predetermined value _T1 , and YES is determined in S3.
In this case, proceed to S5, energize the electromagnetic three-way valve 43, move the idle rotation speed position of the control lever 23a from the normal idle rotation speed position to the open side, and increase the idle rotation speed to a predetermined value.
Proceed to S6. In addition, in the case of NO, the solenoid three-way valve 4
3 is de-energized to maintain the normal idle rotation speed.

Then, it is determined in S6 whether or not the burner device 5 is operating, and if YES, the process advances to S10 and the first burner device 5 is operated.
As in the embodiment, the operation of the burner device 5 is maintained.
Return to S1. If NO in S6, proceed to S7. The exhaust temperature at the inlet of trap 4 is a temperature suitable for self-combusting exhaust particulates only by exhaust heat (e.g. 600℃).
If the temperature is less than 600°C, search the memory 30 for the amount of collected exhaust particulates per unit time based on the rotational speed and load of the engine, and calculate the cumulative amount M by integrating it at predetermined intervals. calculate. In addition, when the exhaust temperature is 600°C or higher, the trap 4 is self-regenerated only by the exhaust heat, so the amount of exhaust particulates that is self-regenerated per unit time without operating the burner device 5 is calculated from the integrated amount M for a predetermined period of time. Correct the integrated amount by subtracting each time.

It is determined in S5 whether the accumulated amount M calculated in this way has reached the appropriate amount of regeneration for trap 4,
If YES, the process proceeds to S10 and the burner device 5 is activated, while if NO, the process proceeds to S9 and the burner device 5 is maintained in an inoperative state.

As explained above, when the temperature on the outlet side of the trap 4 exceeds a predetermined value, the idle rotation speed is increased regardless of whether or not the burner device 5 is activated, so that the flow rate of exhaust gas discharged from the engine is reduced. The trap can be cooled by exhaust air. At this time, since the idle rotation speed is increased when the exhaust gas temperature at the outlet of the trap 4 is above a predetermined value, it can be used not only when the burner device 5 is activated, but also in the case of self-regeneration using only exhaust heat without activating the burner device. Also, the inside of the trap can be cooled by the exhaust flow, and the temperature inside the trap can be suppressed when cooling of the trap is required, so damage to the trap can be prevented. Also, since the trap is cooled by the exhaust flow only when the trap internal temperature is high, the idle rotation speed cannot be increased when the trap is cold, so the trap is not cooled excessively by the exhaust flow and the regeneration time becomes longer. It is possible to prevent this and maintain good regeneration efficiency. Furthermore, since the idle rotation speed is increased only when necessary, wasteful fuel consumption can be prevented.

<Effects of the Invention> As explained above, in the present invention, when the exhaust gas temperature at the trap outlet is higher than a predetermined value, the idle rotation speed is increased from the normal idle rotation speed, so that the exhaust flow rate increases. Since the inside of the trap is cooled by the exhaust flow, for example, even if the burner device is activated or self-regenerated immediately after transitioning from high-speed, high-load operation to idle operation, an excessive rise in the temperature inside the trap can be suppressed, and the trap can be cooled down. Damage to the fuel can be prevented, and wasteful fuel consumption can also be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a flowchart of the same, and FIG. 4 is a block diagram showing a conventional example. 4... Trap, 5... Burner device, 6... Control device, 23a... Control lever, 40...
...stopper lever, 41...diaphragm actuator, 43...electromagnetic three-way valve, 44...outlet side exhaust gas temperature sensor.

Claims (1)

[Claims] 1. An exhaust particulate treatment device for an internal combustion machine comprising a trap installed in an exhaust passage to collect particulates in the exhaust gas, and a burner device that regenerates the trap by heating and burning the exhaust particulates collected by the trap, An exhaust temperature sensor for detecting exhaust gas temperature is provided at the trap outlet, and when the exhaust temperature sensor detects an exhaust temperature equal to or higher than a predetermined value, idle rotation speed switching means sets the engine idle rotation speed higher than when no detection is performed. An exhaust particulate treatment device for an internal combustion engine, comprising: