JPH0625536B2 - Exhaust gas purification device for engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an exhaust gas purifying apparatus for purifying engine exhaust gas, and in particular, combustible particles such as carbon contained in exhaust gas of a diesel engine ( Particulate) is collected and burned and removed.

(Prior Art) Conventionally, various types of exhaust gas purifying devices of this type have been proposed. As an example, for example, JP-A-56-985.
As disclosed in Japanese Laid-Open Patent Publication No. 19, a catalyst filter for collecting combustible particles and the like in exhaust gas to cause an oxidation reaction is provided in an exhaust system of an engine, and liquid, gas and the like are provided upstream of the catalyst filter. An injection device for injecting auxiliary fuel is provided, and the exhaust gas temperature is heated to the ignition temperature of the combustible particles or higher by the oxidation reaction action of the catalyst in the catalyst filter and the combustion promotion action of the auxiliary fuel, and is collected in the catalyst filter. It is known that the combustible particles thus generated are burned and removed to regenerate the filter.

(Problems to be solved by the invention) However, in this conventional engine, the exhaust gas temperature is relatively low when the engine is in the steady operation range (200 to 300 ° C. for a diesel engine). The exhaust gas is not sufficiently heated to the ignition temperature of the combustible particles despite the action of promoting combustion of the fuel. As a result, the catalyst filter may not be reliably regenerated due to poor combustion of the combustible particles, and the back pressure of the engine may increase due to clogging of the catalyst filter, which may interfere with normal operation of the engine.

Therefore, the applicant of the present application has previously provided, in Japanese Patent Application No. 59-64627, an ordinary particulate filter having only a function of collecting combustible particles in place of the catalyst filter in the exhaust system of the engine. As a liquid that promotes the combustion of combustible particles in the exhaust passage upstream of the filter,
For example, by injecting and supplying a liquid in which a catalyst component and a hydrocarbon component are mixed and emulsified, the surfaces of the combustible particles collected by the particulate filter are uniformly covered with the components of the catalyst and the hydrocarbon. It proposes a technique for making the ignition temperature of the combustible particles significantly lower by adhering the same so that the combustible particles are surely burned and removed even during steady operation of the engine where the exhaust gas temperature is low.

By the way, in that case, if the liquid is injected and supplied when the engine is in a high-speed operation range and the exhaust gas amount is large, for example, the liquid injection flow is disturbed by the influence of the exhaust gas flow flowing at a high speed. The phenomenon occurs that the liquid is unevenly attached to a part of the filter surface. However, in order to evenly burn the combustible particles and the like collected in the filter by the liquid, it is necessary to eliminate the above phenomenon.

Also, since the temperature is high when the flow rate of the exhaust gas is large,
Combustion of combustible particles accompanying the injection and supply of the liquid may cause an abnormal increase in combustion temperature, which may cause cracks in the filter. From this point as well, countermeasures are desired.

(Object of the Invention) The present invention has been made in view of the above points, and an object of the invention is to exhaust a liquid that promotes the combustion of combustible particles into a filter when the liquid is injected and supplied to an exhaust passage upstream of the filter. By appropriately controlling the gas amount, it is possible to suppress the uneven distribution of the liquid adhered to the filter surface, and to ensure stable combustion of the combustible particles in the filter to prevent an abnormal rise in the combustion temperature.

(Means for Solving Problems) In order to achieve the above-mentioned object, the solving means of the present invention is an exhaust gas purifying apparatus including a particulate filter for collecting combustible particles and the like in an exhaust system, An injector for injecting and supplying a liquid that promotes the combustion of the combustible particles is disposed upstream of the particulate filter. Further, an exhaust bypass passage that allows the exhaust gas to flow down by bypassing the injector and the particulate filter in the exhaust passage, a flow control valve that controls the amount of exhaust gas that flows down the exhaust bypass passage, and a drive of the flow control valve. The driving means and the control means for controlling the driving means so that the amount of exhaust gas passing through the particulate filter at the time of liquid injection by the injector becomes a set value.

(Operation) With the above configuration, in the present invention, the amount of exhaust gas flowing down the exhaust bypass passage from the engine is controlled by the flow rate control valve driven by the drive unit that receives the output of the control unit during liquid injection by the injector. It is controlled according to the amount of exhaust gas.
That is, for example, when the engine is in the high speed operation range and the exhaust gas amount is large, the flow control valve is opened to increase the exhaust gas amount in the exhaust bypass passage, while the engine is in the low speed operation region and the exhaust gas amount is increased. When the amount of exhaust gas is small, the flow control valve is closed so that the amount of exhaust gas in the exhaust bypass passage is reduced, and the amount of exhaust gas passing through the particulate filter is controlled by controlling the amount of exhaust gas in this exhaust bypass passage. Is kept constant. Therefore, the turbulence due to the exhaust gas flow of the liquid jet flow from the injector, unevenness is suppressed, the liquid is evenly adhered to the surface of the particulate filter evenly, the combustion of the combustible particles in the filter becomes stable, the combustion temperature The occurrence of cracks in the filter due to abnormal rise will be prevented.

First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall construction of a first embodiment of the present invention, wherein 1 is a vehicle swirl chamber type diesel engine having a combustion chamber 2 and a swirl chamber 3 communicating with the combustion chamber 2, and 4 is the engine. A fuel injection pump for injecting fuel into a swirl chamber 3 of No. 1 through a fuel injection nozzle 5, and the fuel injection pump 4 is driven by a crankshaft 1a of an engine 1 in synchronization.

Reference numeral 6 denotes an exhaust passage for discharging the exhaust gas in the combustion chamber 2 of the engine 1. In the middle of the exhaust passage 6, combustible particles containing carbon as a main component in the exhaust gas are trapped. A particulate filter 7 for collecting is provided. The particulate filter 7 is formed by alternately closing the openings at both ends of a large number of honeycomb holes in a honeycomb body made of a porous material, and when exhaust gas passes through partition walls between adjacent honeycomb holes. This is filtered to collect combustible particles and the like in it.

Reference numeral 8 denotes an injector for injecting and supplying a liquid for promoting combustion of the combustible particles into the exhaust passage 6 upstream of the particulate filter 7, and the injector 8 stores the liquid for promoting combustion. The jet port 10a is installed in the tank 9 and the exhaust passage 6 upstream of the particulate filter 7.
An injector 10 having a solenoid opening / closing valve 10b arranged toward the surface, a communication pipe 11 connecting the injector 10 to the tank 9, and an electric liquid supply pump arranged in the middle of the communication pipe 11. 12 is provided, and a predetermined amount (for example, 10 to 100 cc) of liquid in the tank 9 is actuated by the operation of the liquid supply pump 12 and the opening operation of the electromagnetic opening / closing valve 10b of the injector 10.
Is ejected toward the filter 7 and attached to the surface thereof. The liquid that promotes the combustion of the combustible particles is, for example, 0.05 to 0.5% by weight of 1 or 2 or more white metals (Pt, Pd, Rh, Ir).
Water-soluble compound, or 1 to 10% by weight of one or more base metals (V, Cu, Cr, Fe, Ni, Mo,
A catalyst component consisting of a water-soluble salt of Ca, Ba), and 10 to 5
It comprises 0% by weight of kerosene, light oil, heavy oil, alcohol, ketone (oxygenated hydrocarbon) and other hydrocarbons, 1 to 10% by weight of a surfactant for dissolving the hydrocarbon in water, and the balance of water. , Those components are mixed and emulsified.

Further, the exhaust passage 6 on the upstream side of the injector 10 of the injector 8 and the exhaust passage 6 on the downstream side of the particulate filter 7 are connected by an exhaust bypass passage 13, and the exhaust bypass passage 13 exhausts the exhaust gas from the engine 1. The gas is allowed to flow by bypassing the injector 10 of the injector 8 and the particulate filter 7.

Further, at the upstream end portion of the exhaust bypass passage 13, that is, the connection end portion with the exhaust passage 6 on the upstream side of the injector 10, a flow rate control valve including a butterfly valve for controlling the amount of exhaust gas flowing down the exhaust bypass passage 13. 14 are provided. The flow rate control valve 14 is connected to a diaphragm device 16 via a rod 15, and a negative pressure chamber 16a of the diaphragm device 16 is communicated with a vacuum pump 18 via a negative pressure introducing passage 17 and at the same time, the negative pressure is introduced. In the middle of the passage 17, the negative pressure chamber 1 of the diaphragm device 16 is provided.
A duty solenoid valve 20 that linearly switches the communication ratio with the vacuum pump 18 of 6a or the atmosphere opening portion 19 is provided. Driving means 21 is configured to drive the flow control valve 14 by linearly controlling the diaphragm device 16 by 20.

Further, 22 is an injector 10 in the injector 8.
Is a control circuit for controlling the operation of the electromagnetic on-off valve 10b, the liquid supply pump 12, and the duty solenoid valve 20. The control circuit 22 controls the pump shaft rotation speed of the fuel injection pump 4 corresponding to the engine rotation speed. The signal and the signal of the same control sleeve position corresponding to the engine load are input. Reference numeral 23 denotes a first exhaust gas temperature sensor for detecting the exhaust gas temperature T ₁ in the exhaust passage 6 upstream of the particulate filter 7, and 2
4 is a back pressure sensor for detecting the exhaust gas pressure in the exhaust passage 6 immediately upstream of the particulate filter 7, that is, the back pressure of the engine 1, 25 is the exhaust gas temperature T ₂ in the exhaust passage 6 immediately downstream of the particulate filter 7. It is a second exhaust gas temperature sensor that indirectly detects the combustion state of the collected combustible particles in the particulate filter 7, based on which the outputs of these sensors 23 to 25 are input to the control circuit 22. . Thus, the control circuit 22 detects the operating region of the engine 1 on the basis of the output signal of the fuel injection pump 4, and the preset and stored proper back pressure when the filter 7 is not in the clogged state in the operating region. Is searched, and the actual back pressure detected by the back pressure sensor 24 is compared and compared with the appropriate back pressure to determine whether or not the filter 7 is clogged, and the actual back pressure is higher than the appropriate back pressure. When the filter 7 is in a clogged state, an operation signal is output to the liquid supply pump 12 of the injector 8 and the electromagnetic opening / closing valve 10b of the injector 10 to cause the injector 10 to eject the liquid and to cause the injector 8 to eject the liquid. During liquid injection, the duty solenoid of the drive means 21 is adjusted so that the amount of exhaust gas passing through the filter 7 becomes a set value, that is, the back pressure detected by the back pressure sensor 24 becomes substantially constant. By controlling the valve 20 is configured to open and close the flow control valve 14.

Next, the control procedure in the control circuit 22 will be specifically described with reference to the flowcharts shown in FIGS.

In the main routine shown in FIG. 2, first, in step S ₁ after the start, the flow control valve 14 is closed and the exhaust bypass passage 13 is closed.
In steps S ₂ and S ₃ , the engine speed and the engine load are detected based on the shaft speed and the control sleeve position of the fuel injection pump 4, respectively. After detecting the back pressure of the engine 1 based on the output signal of the back pressure sensor 24 in the next step S ₄ , the back pressure of the engine 1 detected in the above steps S ₂ and S ₃ in step S ₅ .
It is judged whether the back pressure has been reduced once to a predetermined back pressure properly set for each operating region, that is, whether the combustible particles collected in the particulate filter 7 have been burned and removed once. performed, the process returns to step S ₄ when this determination is NO. Proceeds to step S ₆ when the determination in Step S ₅ is YES by drop to a predetermined back pressure of the back pressure, whether back pressure detected in the step S ₄ is higher than a predetermined value, i.e., patties filter 7 is determined whether there are any clogging by increasing the collection amount of the combustible particles, subsequent it returns to step S ₂ when this determination is NO step S _3, S
_4. Repeat.

On the other hand, when the determination in step S ₆ is YES, the process proceeds to step S _7, counts the time injection number N of the liquid by the injector 8, the time number of injections N in the next step S _8, in advance As shown in FIG. 4, the current injection amount Q of the liquid is determined by collating with the map of the injection amount characteristics with respect to the number of times the liquid is ejected which is set and stored.

At this time, in the ejection amount characteristic shown in FIG. 4, the ejection amount Q is set to decrease as the ejection number N of the liquid increases. Therefore, the particulate matter increases as the ejection number N of the liquid increases. By utilizing the fact that the amount of catalyst component in the liquid deposited on the filter 7 increases, the amount of liquid (catalyst component) used can be reduced while securing the combustion promoting effect of combustible particles by the deposited catalyst component to some extent. Can be down. Instead of storing such a map of the injection amount characteristics, electrodes are buried facing each end of the particulate filter 7, and the electric resistance value between the electrodes is measured after the filter 7 is regenerated. Accordingly, the liquid injection amount can be determined by directly detecting the deposition amount of the conductive catalyst component on the filter 7. That is, as shown in FIG. 5, the resistance value between the electrodes decreases with an increase in the deposition amount of the catalyst component, so that the characteristic may be used.

After the liquid injection amount Q is determined as described above, the exhaust gas temperature T ₁ of the engine ₁ is detected based on the output signal of the first exhaust gas temperature sensor 23 in step S ₉ , and the exhaust gas temperature is detected in the next step S _10. temperature T ₁ is, performs a crack allowable limit exhaust gas temperature T _a low determines whether than as abnormal temperature range lower limit cracks in the filter 7 by the combustion of the combustible particles with the liquid jet, this Judgment is T ₁
When the NO of ≧ T _A is the filter 7 by liquid injection seeing a state in which cracks are generated returns to step S _9, wait for the decrease in exhaust gas temperature T _1.

On the other hand, when the determination in step S ₁₀ is YES of _T 1 _{<T A,} the step S ₁₁ together with the liquid injection control routine is processing to S _22, step S ₅₁ to S ₅₆ as illustrated in FIG. 3 The exhaust gas amount control subroutine is processed in parallel. To drive the liquid supply pump 12 in the first step S _11, the injection device 8 of the liquid ejecting routine, opening the solenoid valve 10b of the injector 10 in the next step S _12, the surface of the filter 7 a liquid from the injector 10 To spray. "1" to the flag F to the state in step S ₁₃
After storing upright and sets the timer proceeds to step S _14, the elapsed time by the timer in the next step S ₁₅ from the combustible particles of the filter 7 starts ejecting the liquid to fully burn To judge. When the timer times out, after resetting the timer at step S _16, the second exhaust gas temperature sensor at Step S ₁₇ 2
The exhaust gas temperature T ₂ downstream of the filter 7, that is, the exhaust gas temperature that rises due to the combustion of the combustible particles collected by the filter 7 is detected based on the output signal of No. 5, and the next step S
_{At 18} , it is determined whether the exhaust gas temperature T ₂ is higher than a limit value T _B at which the filter 7 is cracked. If this determination is NO at T ₂ ≦ T _B , step S ₁₉
Driving time of the liquid feed pump 12, it is determined whether a predetermined time has elapsed that corresponds to the injection quantity Q of liquid determined in step S _8, shows a non-injection of the determination is determined injection amount Q move to If NO, the process returns to step S ₁₇ to continue the liquid ejection. On the other hand, when the determination in step S ₁₉ is YES, the process proceeds to step S ₂₀ , the electromagnetic opening / closing valve 10b of the injector 10 is closed, and the operation of the liquid supply pump 12 is stopped in step S ₂₁ to inject the injector 8 Exit liquid injection by, then after the flag F erected in step S ₁₃ proceeds to step S ₂₂ to "0", returns to the first step. Further, when the determination in Step S ₁₈ is YES of T _2> T _B is immediately terminated liquid jet moves to step S ₂₀ to S ₂₂ is regarded as a state in which the combustion temperature of the combustible particles is increased abnormally .

On the other hand, in the exhaust gas amount control subroutine, the back pressure upstream of the filter 7 is detected by the back pressure sensor 24 in the first step S ₅₁ , and the amount of exhaust gas passing through the filter 7 is indirectly detected. Then, the detected back pressure in the subsequent step S ₅₂ it is determined whether lower than a predetermined value corresponding to the proper passage of the filter 7 in the exhaust gas, the step S ₅₃ when the determination is YES In order to increase the amount of exhaust gas to the filter 7, the valve opening of the flow rate control valve 14 is reduced to transmit a duty signal to the duty solenoid valve 20 of the driving means 21 while closing the exhaust bypass passage 13. If NO, the process proceeds to step S ₅₄ , and the duty solenoid valve 20 is operated to increase the valve opening of the flow control valve 14 to open the exhaust bypass passage 13 in order to reduce the amount of exhaust gas to the filter 7. It sent to adjust the amount of exhaust gas passing through the filter 7 by the steps S ₅₁ to S ₅₄ so as to maintain the set value. After this, step S ₅₅
Flag F of the liquid ejecting routine it is judged whether the is F = 1 in, repeat the above steps S ₅₁ to S ₅₄ until the determination is made to NO. Then, when the above judgment is NO of F = 0 due to the end of the liquid ejection, step S
_{At 56} , the opening degree of the flow rate control valve 14 is set to zero and the exhaust bypass passage 13 is closed to end the exhaust gas amount control.

Therefore, in this embodiment, by the control operation as described above, while the liquid is being jetted and supplied from the injector 10 of the injector 8 toward the surface of the filter 7, the flow rate control valve 14
The exhaust bypass passage 13 is controlled to be opened / closed by the control described above, and the amount of exhaust gas passing through the filter 7 is maintained at a set value. Therefore, the liquid jet flow injected from the injector 10 of the injector 8 is a high-flow exhaust gas flow. The liquid is not affected and disturbed, and the liquid can be made to adhere uniformly over the entire surface of the filter 7. Therefore, the combustible particles can be uniformly burned by the filter 7, and the regeneration thereof can be favorably performed.

Further, since the exhaust gas amount to the filter 7 is always kept substantially constant when the liquid is injected to the filter 7 in this way, even when the exhaust gas amount is large, such as when the engine 1 is operating at high speed, The combustible particles of No. 7 can be stably burned, the abnormal temperature rise at the time of burning the combustible particles can be suppressed, the occurrence of cracks in the filter 7 can be prevented, and the durability thereof can be improved.

As shown in FIG. 6, the particulate filter 7
A number of electrodes 26 from the downstream end of the honeycomb
26, ... are fitted so that the central part of the filter 7 is longer than that of the peripheral part, and the same kind of the same kind is provided between the electrodes 26, 26, ... And the injector 10 of the injector 8 by the boosting coil 27. By applying a voltage, the injector 10
The jet flow of the liquid jetted from may be diffused to the peripheral portion of the filter 7 by the repulsive force due to electrostatic induction.

That is, in this case, when the liquid is injected into the filter 7, the combustible particles in the central portion of the filter 7 which have a high temperature due to the passage of a large amount of exhaust gas before the injection are burned prior to the peripheral portion having a relatively low temperature. Then, when the passage resistance in the central portion of the filter 7 is partially reduced and exhaust gas passes through the central portion in a concentrated manner, the jet flow of the liquid is It is possible to prevent the jet flow of the liquid from being biased toward the central portion of the filter 7 due to the influence of fluctuation by the diffusion bias to the peripheral portion of the filter 7 due to the electrostatic induction, and the flammability of the filter 7 described above. There is an advantage that an even burning effect of particles can be obtained more reliably.

Further, when the catalyst component in the liquid is magnetizable, a magnetic field may be generated between the injector 10 and the filter 7 to induce the liquid jet flow, and the same effect as the above modification can be obtained. .

In addition, in the above-mentioned examples, a liquid that uses a mixed liquid of a catalyst component and a hydrocarbon component was shown as the liquid that promotes the combustion of the combustible particles. A liquid containing only one of them may be used.

Further, in the above embodiment, the time when the filter 7 is clogged, that is, the time when the liquid is injected to the filter 7 is indirectly detected by the back pressure of the engine 1. However, various other detections are possible. A method can be considered. Hereinafter, each of them will be described as an example. The same parts as those in FIGS. 1 to 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

(Second Embodiment) FIGS. 7 to 9 show a second embodiment of the present invention, in which the liquid injection timing is detected based on the traveling distance of the vehicle.

That is, in the present embodiment, as shown in FIG. 7, instead of the back pressure sensor 24 in the configuration of the first embodiment,
A mileage accumulator 28 that integrates the mileage of the vehicle is used.

Further, when the signal processed by the control circuit 22, as shown in FIG. 8, after detecting the engine load in step S _3, the vehicle travels based on the output of the travel distance integrated meter 28 in the step S ₄ distance detects the integrated value, running the liquid injection to determine the magnitude relationship between the integrated value and a predetermined value of the travel distance in the next step S _6, the filter 7 when the YES mileage> predetermined value I decided to.

Then, in executing the liquid injection to the filter 7, in the exhaust gas amount control subroutine, as shown in FIG. 9, the integrated value of the vehicle traveled distance is detected in the first step S _{51 as} in step S ₄ described above. In the next step S ₅₂ , it is determined whether or not the integrated value is larger than a predetermined amount (different from the determination standard for executing the liquid injection), and then the exhaust to the filter 7 is performed based on the determination result. The configuration is such that the gas amount is adjusted to an appropriate value. The other structure is the same as that of the first embodiment.

Therefore, in this embodiment, the traveling distance of the vehicle is integrated, and when the integrated value reaches a predetermined value, it is determined that the filter 7 is in the clogged state and the liquid injection supply is started. Therefore, the liquid injection start timing is determined. It is possible to easily obtain the signal to be used and to simplify the configuration.

In this case, the control circuit 22 determines the magnitude relationship between the vehicle travel distance integrated by the integrator 28 and the predetermined value by using the integrator 28 that integrates the travel distance of the vehicle. Using a mileage sensor that outputs a signal each time the integrated value of distance reaches a predetermined value,
The liquid ejection to the filter 7 may be started when the output signal of the sensor is input to the control circuit 22.

(Third Embodiment) FIGS. 10 and 11 show a third embodiment in which the liquid injection timing is detected based on the fuel consumption of the engine 1.

In this embodiment, instead of the mileage accumulator 28 in the configuration of the second embodiment, a signal of the fuel supply amount supplied from the fuel tank to the engine 1 and a float in the fuel tank linked to the fuel meter. A fuel consumption integrating meter that integrates the fuel consumption of the engine 1 based on the position signal of is used.

Further, in the control circuit 22, as shown in FIG. 11, after detecting the engine load in step S ₃ , the integrated value of the fuel consumption is detected based on the output of the fuel consumption integrating meter in step S _4. In the next step S ₆ , the magnitude relation between the integrated value of the fuel consumption amount and the predetermined value is YE of fuel consumption amount> predetermined value.
When it is determined to be S, the liquid is ejected to the filter 7.

Then, the exhaust gas amount control subroutine detects the integrated value of the fuel consumption in the step S _51, as shown in FIG. 11, whether or not the fuel consumption in the next step S ₅₂ is greater than a predetermined value It is determined and the amount of exhaust gas to the filter 7 is adjusted based on this determination result.

Therefore, in this embodiment, in order to detect the consumption amount of the fuel that is the source of the combustible particles, the correlation between the detected fuel consumption amount and the collected amount of the combustible particles collected by the filter 7 Is extremely high, and there is an advantage that the clogging state of the filter 7 can be detected with high accuracy.

(Fourth Embodiment) FIGS. 12 to 14 show a fourth embodiment, in which the liquid injection timing for the particulate filter 7 is detected based on the operating time of the engine 1.

That is, as shown in FIG. 12, the control circuit 22 receives an output signal of an operating time accumulator 29 for accumulating time in the ON operation state of the ignition key switch 30, and the ON operation of the ignition key switch 30. The operating time of the engine 1 is indirectly integrated depending on the state.
In addition, instead of the ON operation state of the ignition key switch 30, as shown by a broken line in FIG.
The operating time may be integrated in the first operating state (power generation state).

Further, in the signal processing of the control circuit 22, as shown in FIG. 13, the integrated value of the operating time of the engine 1 is detected by the output signal of the operating time integrating meter 29 in step S ₄ , and the next step S ₆ Then, it is determined whether or not the integrated time has reached a predetermined value, and when it reaches the predetermined value, it is considered that the filter 7 is clogged, and liquid injection to the filter 7 is executed.

Furthermore, as shown in FIG. 14, and detects the integrated operating time at the first step S ₅₁ in the exhaust gas amount control subroutine, whether the integrated operating time in the next step S ₅₂ is longer than a predetermined value By detecting
The amount of exhaust gas to the filter 7 is adjusted.

Therefore, in the case of this embodiment, since the operating time including the idle operating state of the engine 1 can be detected, there is an advantage that the liquid injection timing can be determined with high accuracy.

(Fifth Embodiment) FIGS. 15 to 17 show a fifth embodiment, in which the liquid injection timing to the filter 7 is determined based on the engine speed.

In the present embodiment, as shown in FIG. 15, a rotational speed sensor 32 of electromagnetic type or electromagnetic induction type, which is disposed close to the crankshaft 1a of the engine 1 to detect the engine rotational speed, and an output of the rotational speed sensor 32 are provided. And a revolution speed integrating meter 33 for calculating an integrated value of the engine revolution speed based on the above.

Further, in the main routine of the control circuit 22, as shown in FIG. 16, after the initialization in step S ₁ , the engine load is detected in step S ₃ , and the revolution number integrator 33 is detected in the next step S _4. The integrated value of the engine speed is detected based on the output of
_{At 6} , it is determined whether the integrated value is larger than a predetermined value. Then, when the determination is that the integrated value> the predetermined value is YES,
Liquid is ejected to the filter 7.

Furthermore, large in amount of exhaust gas control subroutine, as shown in FIG. 17, detects the integrated value of the engine rotational speed at the first step S _51, the integrated value in the next step S ₅₂ is than a predetermined value Whether the exhaust gas amount to the filter 7 is controlled based on the result of the determination.

Therefore, in this embodiment, the amount of the combustible particles trapped in the filter 7 is detected based on the integrated value of the engine speed, which has a high correlation therewith, so that the liquid injection timing for the filter 7 can be determined with high accuracy. .

(Sixth Embodiment) FIGS. 18 to 20 show a sixth embodiment, focusing on the fact that the main component of the combustible particles captured by the particulate filter 7 is carbon having conductivity. Then, the collected amount is detected as an electric resistance value.

That is, in the case of the present embodiment, as shown in FIG. 18, a pair of electrodes 34, 34 are embedded facing each end of the particulate filter 7, and the electrodes 34,
A resistance value measuring device 35 for measuring the electric resistance value between the devices 34 is provided, and the output of the measuring device 35 is input to the control circuit 22.

Then, in the control circuit 22, as shown in FIG.
Detecting the electric resistance value between the electrodes 34 on the basis at step S ₄ on an output of the resistance measuring device 35 in the main routine, whether the resistance value in the next step S ₆ is smaller than the predetermined value judge. As the amount of conductive flammable particles collected by the filter 7 increases, the electrode 3
Since the electrical resistance value between Nos. 4 and 34 decreases, when the electrical resistance value becomes smaller than a predetermined value, it is determined that the filter 7 is in the clogging state, and the liquid is ejected to the filter 7.

Further, in the exhaust gas amount control subroutine, as shown in FIG. 20, the electric resistance value between the electrodes 34, 34 is detected in the first step S ₅₁ , and the resistance value is determined to be less than a predetermined value in the next step S _52. The exhaust gas amount flowing to the filter 7 is controlled to a set value by determining whether or not is too small.

Therefore, in this embodiment, since the amount of collected particles in the filter 7 is directly detected, there is an advantage that the liquid injection timing to the filter 7 can be determined more accurately.

In this case, when the deposition amount of the conductive catalyst component on the filter 7 increases due to the increase in the number of times the liquid is ejected, the resistance value between the electrodes 34 and 34 decreases accordingly.
Immediately after regeneration of the particulate filter 7 in a state where combustible particles have been swept away, the initial resistance value between the electrodes 34, 34 is measured and stored, and the initial resistance value is used as a criterion for the regeneration time of the filter 7. Need to cancel.

(Seventh Embodiment) FIGS. 21 to 23 show a seventh embodiment of the present invention, in which a filter 7 is supplied to a filter 7 on the basis of a predetermined functional expression which is set in advance by using engine speed and engine load as variables. The liquid injection timing is determined.

That is, in this embodiment, as shown in FIG. 21, no special sensor for detecting the clogging state of the filter 7 is provided, and the engine speed and the engine speed based on the operating state of the fuel injection pump 4 are set. Reference each signal of engine load.

Then, in the main routine of the control circuit 22, the second
As shown in FIG. ₂ , after detecting the engine speed x ₁ and the engine load x ₂ in steps S ₂ and S ₃ , respectively,
In step S ₄ , a predetermined functional expression C = ∫f (x ₁ , where the engine speed x ₁ and the engine load x ₂ are variables
x ₂ ) dx, the C value is calculated, the magnitude relationship between the C value and the predetermined value is determined in the next step S ₆ , and when the C value is larger than the predetermined value, the liquid ejection to the filter 7 is performed. To do.

Further, in the exhaust gas flow rate control routine, as shown in FIG. 23, the C value is calculated in the first step S _{51 as} in step S _{4 of the} main routine, and the calculated C value is calculated in the next step S _52. The amount of exhaust gas to the filter 7 is controlled by determining whether the value is larger than a predetermined value.

Therefore, in the case of this embodiment, since the amount of particles collected by the filter 7 is detected by both the engine speed x ₁ and the engine load x ₂ , the amount of particles collected can be detected accurately and easily. The liquid injection timing to the filter 7 can be detected accurately.

Then, as a modified example of this embodiment, in addition to the engine speed and the engine load, the engine back pressure used in each of the first to sixth embodiments, the traveling distance of the vehicle, the fuel consumption amount, the engine operating time and the electric power are used. It is also possible to calculate the function by a predetermined function formula including two or more variables of the resistance value and determine the magnitude of the function and the predetermined value to detect the amount of collected particles.

(Effects of the Invention) As described above, according to the present invention, in order to promote the combustion of the combustible particles captured by the filter, the exhaust passage upstream of the particulate filter arranged in the exhaust system of the engine is provided. When the liquid is injected and supplied by the injector, the exhaust gas from the engine is made to flow down by bypassing the injector and the filter so that the flow rate to the filter is almost constant. The turbulence and unevenness caused by the flow can be suppressed and the liquid can be evenly adhered to the filter surface, and the combustible particles in the filter can be burned evenly, and the combustion of the combustible particles can be stabilized, resulting in abnormal combustion temperature. It is possible to suppress the rise and prevent the generation of filter cracks, thus contributing to the realization of reliable combustion removal of combustible particles by liquid injection for combustion promotion. Is something that can be done.

[Brief description of drawings]

1 to 6 show a first embodiment of the present invention, FIG. 1 is an overall schematic configuration diagram, FIG. 2 is an explanatory diagram showing a flow chart of a main routine in a control circuit, and FIG. 3 is the same exhaust gas. Explanatory diagram showing a flow chart of a gas amount control subroutine, FIG. 4 is a characteristic diagram for determining the injection amount with respect to the number of times of liquid injection, and FIGS. 5 and 6 are modification examples.
FIG. 5 is a characteristic diagram for detecting the catalyst component deposition amount on the particulate filter by changing the electric resistance value between the two electrodes, and FIG. 6 is a main part when controlling the jet flow of the liquid component by electrostatic induction. FIG. 7 to 9 are the second
FIG. 7 shows an example corresponding to FIG. 1, and FIG.
FIG. 9 corresponds to FIG. 3, and FIG. 9 corresponds to FIG. 10 and 11 show the third embodiment, FIG. 10 is a view corresponding to FIG. 2, and FIG. 11 is a view corresponding to FIG. 12 to 14 show a fourth embodiment, FIG. 12 is a view corresponding to FIG. 1, FIG. 13 is a view corresponding to FIG. 2, and FIG. 14 is a view corresponding to FIG. 15 to 17 show a fifth embodiment, FIG. 15 is a view corresponding to FIG. 1, FIG. 16 is a view corresponding to FIG. 2, and FIG. 17 is a view corresponding to FIG. 18 to 20 show a sixth embodiment, FIG. 18 is a view corresponding to FIG. 1, FIG. 19 is a view corresponding to FIG. 2, and FIG. 20 is a view corresponding to FIG. 21 to 23 show a seventh embodiment, FIG. 21 is a view corresponding to FIG. 1, FIG. 22 is a view corresponding to FIG. 2, and FIG. 23 is a view corresponding to FIG. 1 ... Engine, 6 ... Exhaust passage, 7 ... Particulate filter, 8 ... Injector, 13 ... Exhaust bypass passage, 14 ... Flow control valve, 21 ... Driving means, 22 ...
Control circuit, 23, 25 ... Exhaust gas temperature sensor, 24 ...
… Back pressure sensor, 28 …… Distance totalizer, 29 …… Driving time totalizer, 30 …… Ignition key switch, 3
1 ... Alternator, 32 ... Rotation speed sensor, 33 ...
Rotation speed integrating meter, 34 ... Electrode, 35 ... Resistance measuring instrument.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideaki Kurita No. 3 Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Kunihiro Yagi No. 3 Shinchi, Fuchu-cho, Aki-gun Hiroshima Prefecture Mazda Corporation (72) Inventor Kenji Okubo 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-56-54914 (JP, A) JP-A-59-155527 (JP, A)

Claims (1)

[Claims] 1. An exhaust gas purifying apparatus for an engine comprising a particulate filter for collecting combustible particles and the like in an exhaust system, wherein a liquid for promoting combustion of the combustible particles is injected and supplied upstream of the particulate filter. And an exhaust bypass passage that allows exhaust gas to flow down by bypassing the injector and the particulate filter in the exhaust passage, a flow control valve that controls the amount of exhaust gas flowing down the exhaust bypass passage, and Driving means for driving the flow control valve, and at the time of liquid injection by the injector,
An exhaust gas purifying apparatus for an engine, comprising: a control unit that controls the driving unit so that the amount of exhaust gas passing through the particulate filter becomes a set value.