JPH052812B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for regenerating a particle collector for capturing particles such as carbon particles in exhaust gas in an internal combustion engine such as a diesel engine.

〓Prior art〓 In a diesel engine, a particle collector is provided in the middle of the exhaust passage to trap combustible particles such as carbon particles in the exhaust gas and prevent them from being released into the atmosphere. This has been known for a long time.

The particle collector has a heat-resistant collection material, and as the amount of collected particles increases, the collection material becomes clogged, increasing ventilation resistance and interfering with the normal flow of exhaust gas. It starts to come. Therefore, in order for a particle collector to be used for a long period of time without interfering with the normal exhaust gas flow of a diesel engine, it is necessary to
When the amount of particles trapped in the particle collector increases, it is necessary to remove them and regenerate the particle collector. This regeneration of the particle collector is carried out because the particles captured by the particle collector are flammable such as carbon particles.
This is generally done by igniting and incinerating the ash, and for this purpose, an electric heater is provided on the upstream end of the collection material, and the electric heater causes the material to adhere to the collection material. The captured particles are ignited at the part that is attached to the upstream end surface, and the flame propagation due to combustion of the captured particles causes the particles at the upstream end of the collection material to reach the particles at the downstream end one after another. A recycling method has already been proposed in which the waste is incinerated and ashed.

〓Problems to be Solved by the Invention〓 In this method of regenerating a particle collector, the captured particles can be easily and reliably ignited, and the flame can be maintained in a good condition without causing the flame to blow out after ignition. It is important to ensure that the virus spreads quickly and reliably.

The present invention makes it possible to easily and reliably ignite the trapped particles when regenerating a particle collector by incinerating and ashing the trapped particles, and also to ensure good and reliable flame propagation after ignition. The object of the present invention is to provide a method for regenerating a particle collector that does not impede engine drivability.

<Means for Solving the Problem> According to the present invention, the problem is solved by a method for regenerating a particle collector, in which the particles collected by the particle collector are ignited by an electric heater, and the particles are burned and incinerated. The flow rate of the exhaust gas flowing through the particle collector is controlled by a first valve, and the flow rate of the exhaust gas flowing through a bypass passage provided to bypass the particle collector and the first valve is controlled. During regeneration, the electric heater provided at the inlet of the particle collector is energized, the first valve is fully closed, the second valve is fully open, and this state is controlled by a second valve. is maintained until the temperature at the inlet of the particle collector reaches a first predetermined temperature indicating ignition of particles, and after reaching the first predetermined temperature, the first valve and the second valve are While setting the opening degree to a preset opening degree for each valve depending on the engine speed and engine load, this state is maintained such that the temperature at the outlet part of the particle collector is maintain the flame until it reaches a second predetermined temperature indicating that the flame has reached it, and after reaching the second predetermined temperature, fully open the first valve and fully close the second valve. This is achieved by a method for regenerating a particle collector characterized by the following.

〓Operations and Effects of the Invention〓 In order to ignite the captured particles using an electric heater, since oxygen is not required to generate electric heat, it is preferable to keep the ignition part as cool as possible, and therefore, it is preferable to keep the ignition part as cool as possible. It is preferable that this does not occur.
Therefore, according to the method of the present invention, when the captured particles are ignited by the electric heater, the first valve is fully closed and the second valve is fully open, thereby completely preventing the gas flow to the particle collector. This is particularly effective with respect to ignition of captured particles by an electric heater.

Detecting the stability of particle ignition based on its temperature is particularly effective in terms of reliability.

Once ignition with a predetermined stability is achieved, certain steps must be taken to stably burn the captured particles and to allow the combustion to proceed from the inlet to the outlet of the particle collector as quickly as possible. It is necessary that optimal airflow be directed through the particle collector. In this case, the optimum air flow rate varies depending on the oxygen concentration in the exhaust gas, and the oxygen concentration in the exhaust gas of a diesel engine is influenced by the operating state of the engine, particularly the rotation speed and load. Therefore, program control of the flow rate of exhaust gas flowing through the particle collector during particle collector regeneration according to the engine speed and engine load is especially effective in optimizing the progress of regeneration by burning the trapped particles. It is valid.

When the combustion of the trapped particles in the particle collector reaches the outlet of the particle collector, the temperature of this part increases due to the flame, so by detecting this, the particle collector can be regenerated. It is possible to quickly confirm that the particle collector has been regenerated, and by fully opening the first valve and the second valve, the operation of the particle collector can be started immediately after the regeneration of the particle collector is completed. Since it is possible to return to full capacity, the non-operation rate of the particle collector for regeneration can be kept to a minimum.

〓Examples〓 The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing one embodiment of an apparatus for carrying out the method for regenerating a particle collector according to the present invention. In FIG. 1, 1 indicates an inlet pipe, and 2 indicates an outlet pipe, and the inlet pipe 1 is connected to an exhaust port of an internal combustion engine (not shown). The inlet pipe 1 and the outlet pipe 2 are connected by a particle collector 3, and are also connected by a bypass pipe 6 that bypasses the particle collector 3.

The particle collector 3 has a collection material 4 made of a heat-resistant foam filter or honeycomb filter.
The collecting material 4 is adapted to capture particles such as carbon particles in the exhaust gas passing therethrough. An electric heater 5 is provided on the upstream end surface of the capture material 4, and a current from a battery power source 7 is selectively supplied to the electric heater 5 via an electric switch 8.

Near the connection end of the inlet pipe 1 to the particle collector 3,
In other words, the valve 9 is located near the upstream side of the particle collector 3.
However, valves 10 are provided in the middle of the bypass pipes 6, respectively. Valves 9 and 10 have valve shafts 11 and 1, respectively.
It is constructed as a butterfly valve supported by a diaphragm device 13 and 14, and is individually driven to open and close by diaphragm devices 13 and 14, respectively. The diaphragm devices 13 and 14 each have a diaphragm chamber 16,
When negative pressure is not introduced to 17, valves 9 and 1
0 to the fully open position, whereas when negative pressure is introduced into the diaphragm chambers 16, 17, the valve 9
and 10 are opened, and the opening degrees of valves 9 and 10 are increased in accordance with the increase in negative pressure.

Diaphragm chambers 16 and 17 each have a conduit 18,
19 to port a of the negative pressure control valves 20 and 21. In addition to port a, each of the negative pressure control valves 20 and 21 has an atmospheric port b and a negative pressure port c, and the negative pressure port c is connected to a negative pressure pump (not shown) through conduits 22 and 23. , which allows more negative pressure to be applied. Negative pressure control valves 20 and 21 are configured as electromagnetic valves, and negative pressure control valve 20 connects port a to negative pressure port c when energized, and connects port a to atmospheric port b when de-energized. The pressure control valve 21 connects port a to atmospheric port b when energized, and connects port a to negative pressure port c when de-energized.

25 indicates a control device. The control device 25 is an electric type including a microcomputer, etc., and receives information about the exhaust gas temperature from a temperature sensor 26 attached to the exhaust gas inlet of the particle collector 3, and also receives information about the exhaust gas from the particle collector 3. The temperature sensor 27 provided at the outlet receives information regarding the exhaust gas temperature, the rotation speed sensor 28 provides information regarding the rotation speed of the internal combustion engine, and the load sensor 29 provides information regarding the load of the internal combustion engine. to open/close the electric switch 8 and the negative pressure control valve 20,
21 is controlled.

Next, the operation of the particle emission prevention device constructed as described above will be explained with reference to the flowchart shown in FIG.

The routine of the flowchart shown in FIG. 2 is executed every revolution of the internal combustion engine.

First, in step 1, the temperature sensors 26, 2
7. Information provided by the rotation speed sensor 28 and load sensor 29 is read.

Next, in step 2, it is determined whether flag F is 1 or not. When the flag F=1, it means that regeneration of the particle collector 3 has already started, and when the flag F=1, it means that the regeneration of the particle collector 3 has not yet been started. When the flag F is not 1, the process proceeds to step 3, in which the engine speed is integrated.
The rotational speed integrated value N is determined.

Next, the process advances to step 4, in which it is determined whether the rotational speed integrated value N is greater than or equal to a predetermined value A. When N≧A, particle collector 3
This is the time when the particle collector 3 should be regenerated, and when N≧A is not satisfied, it is not necessary to regenerate the particle collector 3 yet. When N≧A is not satisfied, the process returns to step 1.

When N≧A, the routine advances to step 5, in which the rotational speed integrated value N is reset to zero and the flag F is set to 1.

Next, the process advances to step 6, in which the electric switch 8SW is energized, and the negative pressure control valve 20 (VCV1) and the negative pressure control valve 21 are energized.
(VCV2) is energized. This energizes the electric heater 5, which generates heat, introduces negative pressure into the diaphragm chamber 16, and brings the valve 9 to the fully closed position as shown by the imaginary line in FIG. Also, atmospheric pressure is introduced into the diaphragm chamber 17, bringing the valve 10 to the fully open position as shown in phantom in FIG. At this time, a closed space is formed between the upstream end of the collection material 14 of the particle collector 3 and the valve 9, and the exhaust gas trapped in this space is heated by the electric heater 5. Ru. Incidentally, at this time, no exhaust gas flows into the particle collector 3, and all exhaust gas discharged from the internal combustion engine flows through the bypass pipe 6.

After step 6, return to step 1 and proceed to step 2. Since the flag F=1 at this time, the process advances to step 7, and in this step,
It is determined whether the exhaust gas temperature Ti in the space detected by the temperature sensor 26 is greater than a predetermined value B or not. When T ₁ =B is not the case, the process returns to step 1, and the electric heater 5 is continuously energized to maintain the state in which the valve 9 is in the fully closed position and the valve 10 is in the fully open position.

When T ₁ ≧B, it means that the particles adhering to the upstream end surface of the collection material 4 are ignited by the exhaust gas in the space, and in this case, step 8
In this step, the valve opening degree information stored in advance in the storage device according to the engine speed and the engine load is detected by the engine speed detected by the engine speed sensor 28 and by the load sensor 29. It is read out according to the engine load.

Next, the process advances to step 9, in which the electric switch 8 is opened to stop energizing the electric heater 5, and the negative pressure control valves 20 and 21 are given a duty ratio according to the valve opening information. A pulse signal is given. As a result, the negative pressure control valves 20 and 21 repeatedly connect the port a to the atmospheric port b and the negative pressure port c according to the duty ratio of the pulse signal.
A predetermined negative pressure is introduced into valves 6 and 17, and both valves 9 and 10 are brought to a predetermined intermediate opening position.
At this time, valves 9 and 10 are driven in opposite directions, that is, when the opening amount of valve 9 increases, valve 1
When the opening amount of the valve 0 decreases and the opening amount of the valve 9 decreases, the opening amount of the valve 10 increases, which causes the particle collector 3 to have a predetermined amount of energy regardless of the operating state of the internal combustion engine at that time. A certain amount of exhaust gas flows, and the remaining exhaust gas flows through bypass pipe 6. As described above, when a predetermined flow rate of exhaust gas flows through the particle collector 3,
The oxygen in the exhaust gas promotes the combustion of the collected particles, and the flame propagates downstream along with the gas flow.
The particles collected by the collection material 4 are burned and incinerated one after another. By controlling the flow rate of exhaust gas flowing through the particle collector 3 and the flow rate of exhaust gas flowing through the bypass pipe 6 by the valves 9 and 10 in this way, particles can be collected without obstructing the flow of exhaust gas. Exhaust gas corresponding to the engine speed and engine load stored in the storage device flows into the engine 3 in accordance with the engine speed and engine load at that time. By setting the exhaust gas flow rate to a relatively small value that is effective for promoting flame propagation during regeneration of the particle collector 3, the regeneration of the particle collector 3 can be performed quickly and the flame can be blown. This is done reliably without any disappearance.

After step 9, the process proceeds to step 10, in which it is determined whether the temperature _T0 of the exhaust gas coming out of the particle collector 3 detected by the temperature sensor 27 is equal to or higher than a predetermined value C. A determination is made.
When T ₀ ≧C, the flame reaches the rear end of the particle collector 4, and the temperature of the exhaust gas coming out of the particle collector 3 becomes extremely high. It is determined that the regeneration of the particle collector 3 has been completed. That is, when T ₀ ≧C, proceed to step 11, set flag F to 0, and then proceed to step 1.
2, and in this step, the negative pressure control valve 2
The power supply to 0 and 21 is stopped. At this time, atmospheric pressure is introduced into the diaphragm chamber 16 to bring the valve 9 to the fully open position, and negative pressure is introduced to the diaphragm chamber 17 to bring the valve 10 to the fully closed position. Therefore, at this time, all of the exhaust gas flows through the particle collector 3, and the particle collector 3 resumes collecting particles in the exhaust gas.

Although the present invention has been described in detail above with reference to specific embodiments, it is understood by those skilled in the art that the present invention is not limited thereto, and that various embodiments can be made within the scope of the present invention. It would be obvious to

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of an apparatus for carrying out the method for regenerating a particle collector according to the present invention;
FIG. 2 is a flowchart showing the procedure for regenerating a particle collector according to the present invention. 1... Inlet pipe, 2... Outlet pipe, 3... Particle collector, 4... Collection material, 5... Electric heater, 6... Bypass pipe, 7... Battery power supply, 8... Electric switch , 9, 10... Valve, 11, 12... Valve stem, 1
3, 14... diaphragm device, 16, 17...
Diaphragm chamber, 18, 19... Conduit, 20, 2
1... Negative pressure control valve, 22, 23... Conduit, 25...
...Control device, 26, 27...Temperature sensor, 28...
...Rotation speed sensor, 29...Load sensor.

Claims (1)

[Claims] 1. A method for regenerating a particle collector in which the particles collected by the particle collector are ignited by an electric heater to burn and incinerate the particles, and the flow rate of the exhaust gas flowing through the particle collector is set to a first level. and a second valve to control the flow rate of exhaust gas flowing through a bypass passage provided to bypass the particle collector and the first valve, and at the time of regeneration, the inlet portion of the particle collector is controlled by a second valve. At the same time, the first valve is fully closed and the second valve is fully opened, and this state is maintained until the temperature at the inlet of the particle collector indicates particle ignition. and after reaching the first predetermined temperature, the opening degrees of the first valve and the second valve are set in advance for each valve according to the engine speed and the engine load. and maintain this state until the temperature of the output part of the particle collector reaches a second predetermined temperature indicating that the flame has reached the outlet part of the particle collector. . A method for regenerating a particle collector, comprising fully opening the first valve and fully closing the second valve after reaching the second predetermined temperature.