JPS61164019A - Exhaust gas purifying device of engine - Google Patents

Abstract

PURPOSE:To realize stable combustion of a collected particle, by equipping an injection device, which injects combustion promoting fluid, in the upstream of a particulates filter provided in an exhaust system and actuating this device when starting of an engine is detected. CONSTITUTION:In a purifying device providing a particulates filter 7 for catching a combustible particle in exhaust gas in the half way of an exhaust passage 6, said filter provides in its upstream side in the exhaust passage 6 an injection device 8 injecting combustion promoting fluid of the combustible particle. This injection device 8, being constituted by a tank 9, injector 10 and a pump 12 or the like, is controlled by a control circuit 13. That is, the injection device 8 is controlled so as to be operated when an engine 1 is started after the filter 7 is placed in a blocked condition by an increase of an accumulated quantity of combustible particle, in this way the injection device 8, injecting the fluid from the injector 10 toward a surface of the filter 7, realizes stable combustion of the combustible particle when the filter 7 is regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust gas purification device that purifies exhaust gas from an engine, and in particular, to an exhaust gas purification device that purifies exhaust gas from a diesel engine, etc.
It relates to a device that collects and burns off combustible particulates (particulates) such as carbon contained therein.

(Prior Art) Various exhaust gas purification devices of this type have been proposed in the past. As an example, for example, JP-A-56-985
As disclosed in Publication No. 19, a catalytic filter is installed in the engine exhaust system to collect combustible particles in the exhaust gas and undergo an oxidation reaction, and upstream of the catalytic filter, a catalytic filter is installed to combust the combustible particles. By installing an injection device that injects liquid fuel as a liquid that promotes , a filter is known in which combustible particles collected on a catalyst filter are burned and removed to regenerate the filter.

(Problem to be Solved by the Invention) In this case, if the above-mentioned liquid is injected and supplied when the engine is in a high-speed operating range and the amount of exhaust gas is large, the liquid jet flow will be at a high speed. Under the influence of the flowing exhaust gas flow, the liquid becomes turbulent and adheres to a portion of the filter surface.

This phenomenon needs to be eliminated in order for the liquid to evenly burn the combustible particles collected by the filter.

In addition, the present applicant previously proposed in Japanese Patent Application No. 59-64627 that the ignition temperature of combustible particles is significantly lowered, and combustible particles are reliably burned and removed even during steady operation of the engine with low exhaust gas temperature. In order to reduce the amount of combustible particles, an ordinary particulate filter that only has the function of collecting combustible particles is installed in the engine exhaust system instead of a catalytic filter, and the exhaust passage upstream of the particulate filter is filled with combustible particles. As a liquid that promotes combustion, for example, a mixed emulsion of a catalyst component and a hydrocarbon component is injected and supplied, and each component of the catalyst and hydrocarbon is uniformly distributed on the surface of the combustible particles collected in the particulate filter. We are proposing a technique for adhesion.

In that case, when the liquid is injected and supplied under conditions where the exhaust gas temperature of the engine is high, some of the solvent other than the catalyst components is absorbed into the exhaust gas during the process in which the liquid injected from the injector nozzle reaches the surface of the filter. The catalyst component is vaporized by the heat of the gas, and the crystals of the catalyst component adhere to the filter surface without being highly dispersed.There is room for improvement in terms of effectively utilizing the catalytic activity by uniformly attaching the catalyst component to the filter surface. There is.

In addition, at the above exhaust gas temperature, the solvent continues to vaporize even after the liquid adheres to the filter surface, so the permeation effect of the catalyst component into the downstream part of the filter is reduced, and stable combustion of combustible particles is not achieved. Enough is enough.

(Objective of the Invention) The present invention has been made in view of the above points, and its object is to adjust the timing for injecting and supplying a liquid that promotes the combustion of combustible particles into the exhaust passage upstream of the filter in accordance with the operating state of the engine. By setting it appropriately, it is possible to uniformize the adhesion of the liquid to the filter surface and to ensure stable combustion of combustible particles in the filter.

(@Means for solving the illumination point) In order to achieve the above object, the solution means of the present invention is an engine exhaust gas purification device equipped with a particulate filter that collects combustible particles etc. in the exhaust system. An injector is disposed upstream of the particulate filter to inject and supply a liquid that promotes combustion of the combustible particles.

Further, a starting detection means for detecting the starting of the engine is provided, and the injector is controlled to operate when the engine is started based on the output of the starting detection means.
The structure includes 11 means.

(Function) With the above configuration, in the present invention, when the engine is started in which the particulate filter has become clogged due to the accumulation of combustible particles such as carbon, the startup detection means detects this state. I receives the output of the detection means at the time of starting
The injector is actuated under the control of the 111 means to inject a liquid that promotes combustion of combustible particles upstream of the particulate filter. At that time, when the engine is started, the flow rate of exhaust gas is small and its temperature is low, so the liquid jet flow is less likely to be disturbed by the influence of the exhaust gas flow, and the liquid containing the catalyst component is In this case, vaporization of the solvent of the liquid injected from the injector is effectively suppressed. As a result, the liquid adheres uniformly to the surface of the filter, and in the case of the liquid containing a catalyst component, the permeation effect of the catalyst component to the downstream part of the filter is ensured. It is possible to stably and reliably burn the harmful particles.

<Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the overall configuration of an embodiment of the present invention, in which reference numeral 1 denotes a swirl chamber type diesel engine equipped with a combustion chamber 2 and a swirl chamber 3 communicating with the combustion chamber 2; This fuel injection pump injects and supplies fuel through a fuel injection nozzle 5, and the fuel injection pump 4 is driven by the engine 1 in synchronization with the engine 1.

Reference numeral 6 denotes an exhaust passage for discharging the exhaust gas in the combustion chamber 2 of the engine 1, and a part of the exhaust passage 6 traps combustible particles mainly composed of carbon in the exhaust gas. A particulate filter 7 is provided to collect the particles. The particulate filter 7 alternately closes every other #I opening of a large number of honeycomb holes in a honeycomb body made of a porous material, and exhaust gas passes through partition walls between adjacent honeycomb holes. At the same time, it is filtered to collect combustible particles.

Further, 8 is an injector for injecting and supplying a liquid for promoting combustion of the combustible particles to the exhaust passage 6 upstream of the particulate filter 7, and the injector 8 stores the liquid for promoting combustion. A spout 10a is connected to the tank 9 and the exhaust passage 6 upstream of the particulate filter 7.
An injector 10 disposed toward the surface and having an electromagnetic on-off valve 10b, a communication pipe 11 connecting the injector 10 to the tank 9, and an electric liquid supply pump disposed in the middle of the communication pipe 11. 12, the liquid in the tank 9 is supplied to a predetermined m<for example, 10 to 100 cc> by the operation of the liquid supply pump 12 and the opening operation of the electromagnetic on-off valve 10b of the injector 10.
It is made to inject toward the filter 7 from a, and to make it adhere to the surface. The liquid that promotes the combustion of the combustible particles is, for example, 0.05 to 0.5% by weight.
White metals (Pt, Pd, R
t+, Ir> water-soluble compound, or 1 to 10% by weight
base metals (V, Ctl, Cr
, Fe, Ni, Mo, Ca, 8a) and a hydrocarbon such as kerosene, light oil, heavy oil, alcohol, ketone (oxygenated hydrocarbon), etc. in an amount of 10 to 50%,
It consists of 1 to 10% by weight surfactant for dissolving the hydrocarbon in water, and the rest is water, and these components are mixed to form an emulsion.

Further, 13 is an injector 10 in the injector 8.
An Illtli circuit for controlling the operation of the electromagnetic R closing valve 10b and the fluid supply pump 12, and the control circuit 13 receives a signal of the pump shaft rotation speed of the fuel injection pump 4 corresponding to the engine rotation speed, The control sleeve position signal corresponding to the engine load is input. Further, 14 is a cranking switch which is turned ON by the operation of the starter for starting the engine to detect when the engine 1 is started, and 15 is the exhaust gas in the exhaust passage 6 immediately upstream of the particulate filter 7. a back pressure sensor that detects the back pressure of the engine 1;
16 is an exhaust passage 6 immediately downstream of the particulate filter 7
The exhaust gas temperature sensor indirectly detects the combustion state of combustible particles collected in the particulate filter 7 based on the exhaust gas temperature T in the switch 1.
4. Each output of the sensors 15 and 16 is input to the control circuit 13. The control circuit 13 detects the operating range of the engine 1 based on the output signal of the fuel injection pump 4, and determines the preset and stored appropriate back pressure when the filter 7 is not clogged in that operating range. Search for
The actual back pressure detected by the back pressure sensor 15 is compared with the appropriate back pressure to determine whether or not the filter 7 is clogged.
When the injector 8 is clogged, an activation signal is sent to the liquid supply pump 12 and the electromagnetic on-off valve 10b of the injector 10 so that the injector 8 is activated based on the output signal of the cranking switch 14 when the engine is subsequently started. A control means is configured to output the following and cause the injector 10 to inject the liquid.

Next, the control operation in the above embodiment will be explained with reference to the flowchart shown in FIG.

First, initialization is performed in step S+ after the start, and then, in step 32.83, the engine rotation speed and engine load are detected based on the shaft rotation speed of the fuel injection pump 4 and the control sleeve position, respectively. After detecting the back pressure of the engine 1 based on the output signal of the back pressure sensor 15 in the next step S4, step Ss
In other words, whether or not the back pressure has decreased once to a predetermined back pressure that is properly set in advance for each operating range of the engine 1 detected in step S2.83 above, that is, if the particulate filter 7 It is determined whether or not the combustible particles have been burned and removed once, and if this determination is No, the process returns to step S4.

If the determination in step S5 is YES because the back pressure has decreased to a predetermined back pressure, the process moves to step S6, and it is determined whether or not the back pressure detected in step S4 is higher than the predetermined back pressure, that is, the particulate filter 7 is in a clogged state due to an increase in the amount of collected combustible particles, and if this determination is No, the step S described above is performed.
Return to step 2 and perform subsequent steps 83, 84,...
repeat.

On the other hand, if the determination in step S6 is YES, the process moves to step S7, where the current injection number N of the liquid by the injector 8 is counted, and in the next step S8, the current injection number N is calculated in advance as shown in FIG. The current injection amount Q of the liquid is determined by comparing it with a map of the injection amount characteristics for the number of liquid injections that has been set and stored as shown in FIG.

At this time, in the injection amount characteristic shown in FIG. 3 above, the injection IQ is set to decrease as the number of liquid injections N increases, so the particulate filter Utilizing the increase in the amount of liquid catalyst component deposited on 7, while ensuring a certain degree of combustion promotion effect of combustible particles by the deposited catalyst component, reducing the amount of liquid (catalyst component) used and reducing costs. can be achieved.

After determining the liquid injection amount Q as described above, it is determined in step S9 whether or not the cranking switch 14 is operating 0Nil1, that is, whether or not the engine 1 is at the time of starting. If this determination is NO, Assuming that no liquid injection is to be performed, step S9 is continued and the engine is started.

Then, the engine 1 enters the starting state and the above step S
If the determination in step 9 is YES, the liquid injection control routine of steps S to S21 is executed.

The first step S+e of this liquid injection routine drives the liquid supply pump 12 of the injector 8, and the next step S+e drives the liquid supply pump 12 of the injector 8.
Open the solenoid valve 10b of the injector 10 at n,
Liquid is injected from the injector 10 onto the surface of the filter 7. After setting "1" to 7lag F and storing that state in step S12, the process moves to step S13 to set a timer, and in the next step S14, the timer causes the combustible particles in the filter 7 to inject the liquid. The progress of FtIWR from the time it starts until it is fully burned is determined. and,
When the timer times out, the timer is reset in step S+s, and then, in step S+s, the exhaust gas temperature T1 downstream of the filter 7, that is, the combustible gas collected in the filter 7, is determined based on the output signal of the second exhaust gas temperature sensor 16. detects the exhaust gas temperature rising due to the combustion of harmful particles,
In the next step S+y, it is determined whether the exhaust gas temperature IT is higher than the allowable limit value TB that causes cracks to occur in the filter 7. If this judgment is No (T≦T8), the process moves to step S+s, and it is determined whether or not the drive time of the liquid supply pump 12 has elapsed for a predetermined time corresponding to the liquid injection amount Q determined in step Ss. If the determination is NO indicating that the determined injection amount Q has not been injected, the process returns to step S+s to continue the liquid injection.

On the other hand, if the determination in step S+s is YES, the process moves to step S+s, and the injector 1
0 electricity 1r# Close valve 10b and step S
At step s, the operation of the liquid supply pump 12 is stopped to end the liquid injection by the injector 8, and then the process moves to step S2+, where the flag F set at step S+z is set to "0", and then the first step S Return to book. Moreover, when the judgment in step Sτ7 is YES on T>T day,
It is assumed that the combustion temperature of the combustible particles has increased abnormally, and the process immediately moves to steps S+s to 821 to end the liquid injection.

Therefore, in this embodiment, the control operation as described above causes the injector 8 to operate when the engine 1 is started after the filter 7 has become clogged due to an increase in the amount of combustible particles deposited in the injector 8. A liquid is injected and supplied from the injector 10 toward the surface of the filter 7, and the liquid adheres to the surface of the filter 7. After that, mainly engine 1
When the exhaust gas temperature rises with operation, the accumulated combustible particles are ignited and burned due to the effect of lowering the ignition temperature of the liquid adhering to the surface of the filter 7, and the filter 7 is regenerated.

In that case, since the exhaust gas temperature at the time of starting the engine that performs the liquid injection is low, it is possible to suppress the solvent from vaporizing before the liquid injected from the injector 10 of the injector 8 reaches the surface of the filter 7. The catalytic components are maintained in a highly dispersed state and adhere uniformly to the surface of the filter 7, so that the catalytic activity can be effectively utilized. Moreover, when starting the engine, there are few exhaust gas sources, so injector 1
The liquid jet stream injected from zero is less likely to be disturbed by the influence of the exhaust gas flow, and the liquid can be more evenly deposited over the entire surface of the filter 7. Therefore, the filter 7 can remove combustible particles. can be burned evenly and regenerated well.

Furthermore, as mentioned above, since the exhaust gas temperature is low when the engine is started, even after the liquid from the injector 8 adheres to the surface of the filter 7, the vaporization of the solvent is suppressed, and the catalyst components are transferred to the downstream part of the filter 7. Penetration becomes smooth and combustible particles can be stably burned.

In this example, a liquid mixture containing a catalyst component and a hydrocarbon component was used as the liquid that promotes the combustion of combustible particles. A liquid containing only one of the two may also be used.

(Effects of the Invention) As described above, according to the present invention, a liquid is injected upstream of a particulate filter disposed in the exhaust system of an engine to promote combustion of combustible particles collected in the filter. When the liquid is injected and supplied by the device, the injection timing is set at the time of engine startup when the exhaust gas flow rate is low and the temperature is low. This suppresses the turbulence and unevenness of the liquid jet flow caused by the exhaust gas flow, and allows the liquid to be delivered to the filter surface. Furthermore, by suppressing the vaporization of the liquid solvent, the flammable particles in the filter can be burned evenly and stably, and therefore the flammable particles in the exhaust gas can be reduced by spraying the liquid for combustion promotion. This can contribute to the realization of reliable combustion removal of particles.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall schematic diagram, Fig. 2 is an explanatory diagram showing the control procedure of the main routine in the control circuit, and Fig. 3 is for determining the injection amount with respect to the number of liquid injections. FIG. DESCRIPTION OF SYMBOLS 1... Engine, 6... Exhaust passage, 7... Particulate filter, 8... Injector, 13... Control circuit, 14... Cranking switch, 15... Back pressure sensor , 16... Exhaust gas temperature sensor. Figure 3 Large 4 shots Kai → Multi

Claims (1)

[Claims] (1) In an exhaust gas purification device for an engine equipped with a particulate filter that collects combustible particles in the exhaust system, injection supplies a liquid that promotes combustion of the combustible particles upstream of the particulate filter. and a start detection means for detecting when the engine is started, and a control means that receives the output of the start detection means and controls the injector to operate when the engine is started. Features: Engine exhaust gas purification device.