JPS5898651A - Exhaust-gas purifying apparatus for diesel engine - Google Patents

Abstract

PURPOSE:To prevent sticking of viscous oily substances to the intake system of a Diesel engine, by arranging a heating resistor in a filter diaposed in an EGR (exhaust-gas recirculation) passage for capturing fine combustible particles, and controlling the amount of current supplied to the heating resistor at the time when an EGR valve is opened. CONSTITUTION:A filter 2 for capturing fine combustible particles contained in EGR gas is disposed in an EGR passage, and heating resistor 4 and a temperature measuring thermocouple 5 are arranged in the filter 2. On the other hand, output signals of an engine speed sensor 13, a sensor 14 for detecting the temperature of cooling water, and a load sensor 15 are furnished to an EGR control circuit 12, and an EGR control valve 8 is controlled by a three-way valve 9 according to the operational conditions of an engine. When recirculation of exhaust gas is started, an electromagnetic relay 10 is energized by the control circuit 12, and a current supply control means 1 starts current-supply to the heating resistor 4. The current-supply control means 1 controls the amount of current to be supplied to the resistor 4 by effecting ON-OFF switching of a relay 3 according to the output of the thermocouple 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas purification device for a diesel engine.

In recent years, it has become urgent to establish measures to purify exhaust gas from diesel engines. In order to reduce NOx, which is one of the harmful components in the gas of a diesel engine, it is recommended to suck a portion (several percent to about 80%) of the exhaust gas from the exhaust pipe and recirculate it into the intake air. Although it is effective, on the other hand, when EGji is performed, carbonaceous particles contained in the recycle exhaust gas are mixed into the intake air, which may cause wear of the sliding parts of the engine, increase in the amount of carbon in the oil, or increase the amount of carbon in the oil. The problem is that the properties deteriorate considerably.

This invention is based on the EGB Nyoro N (J) of a diesel engine.

It is an object of the present invention to advantageously solve the above-mentioned problems while reducing the amount of water.

In other words, this invention's combined gas purification device for teasel-a combat can be used for combined gas purification (/lt
A filter provided in M for capturing combustible imitation particles, a heating resistor for heating filter L, and 11-cue.
and an energization control device that controls energization to the photothermal resistor so as to sequentially burn the combustible iron particles captured by the filter. Heat-resistant meshes and fiber aggregates (e.g. steel wool) are used as materials, and ceramic materials include copephyte, mullite,
In addition to non-conductive materials such as alumina, stabilized zirconia, forsterite, steatite, and silicon nitride, there are also conductive materials such as molybdenum disilicide and silicon carbide ceramics.
Porous rings (for example, honeycomb structures) or regular or irregular aggregates of spongy bodies or monolithic systems with curved connecting holes V'3 can be widely used.

In addition, as a heating resistor, the filter can be used to at least partially combust the combustible mimic particles. Any structure may be used as long as the filter can be electrically heated more efficiently than above, but it is difficult to heat the filter at least partially to 600°C. The photothermal resistor can be provided separately from the filter, inside the filter, or near the surface of the filter, but if the filter is made of a conductive material (metal or
Using electrically conductive ceramics to make the filter itself function as a photothermal resistor also reduces the electrical disconnection between the filter and the casing.

In other words, a major feature of this invention is that the filter automatically eliminates the accumulation that would lead to particulate matter, and as a result, the recirculated exhaust gas is kept at a relatively low temperature and is returned to the intake pipe and sent to the intake system. It is also effective in reducing the build-up of oily sticky substances, and in low temperatures such as winter, it helps to unify the fuel by removing the intake air all at once, and reduces the formation of IiC and CO in the waste. I can do it.

Of the methods for controlling the conduction to the photothermal resistor, the simplest and most advantageous method is to control switching by repeatedly turning on and off a switch provided in the circuit for supplying current to the photothermal resistor. When the filter is coated with carbon, it is heated by the heating resistor after an excessive interval, and once it reaches the combustion temperature, the combustion reaction heat continues the combustion on its own. It will be particularly effective if the filter is endowed with oxidation reaction catalytic properties. The catalyst tL property is given by setting the combustion start temperature of carbon to 1.
It also has the effect of lowering the temperature by 00°C or more. On/Off@
The control circuit may use a timer circuit to provide the duty ratio in response to a signal from a sensor that horizontally controls the temperature of the filter, or may provide a duty ratio corresponding to preset operating conditions in accordance with the operating conditions. Mixed use of these is also possible.

I will further congratulate you based on the example of the actual gallery.

First, Fig. 1 shows an engine using the first embodiment of the present invention, the exhaust gas gauze device for a diesel lji@ (hereinafter referred to as engine).
115 is a thermocouple that is a sensor that detects the temperature of the filter 2. , 6 is the engine exhaust pipe, wholesale exhaust manifold, 7 is the intake bud, or intake manifold,
8 is a control valve (hereinafter referred to as the gum valve) that controls the amount of exhaust gas returned from the exhaust manifold 6 to the intake manifold 7; 9 is an EG valve 8;
A three-way solenoid valve 10 controls the opening of the kJGn valve 8 by controlling the pressure inside the diaphragm chamber of the diaphragm chamber, and 10 is a power supply that controls on/off the power from the battery 11 and inputs it to the energization control device Ii1. Relay 12 is an engine rotation sensor 18, an engine cooling water temperature sensor 14, and an engine load sensor 15.
a tub control device that controls the three-way solenoid valve 9 by obtaining engine status information from the
6 is an accelerator lever that slows down the engine load sensor 15.
Fuel injection pump equipped with, and M S Hull 1jLL
It is a main switch that turns on and off the gap filling system of the entire system.

As shown in Fig. 2, this energizing device is equipped with an operation amplifier 18, and the line voltage applied to terminal a is connected to resistances 1 and 2 or resistances 1 and 2 and L.
2 reference voltage determined by dividing the voltage by 5) f V r
e 1° is created and input to the non-inverting input side,
Then, according to the temperature VI signal from the thermocouple inputted to the inverting input side from the inputs d and e, for example, if the temperature is 500°C or higher, the output of the operational amplifier 18 becomes one level and is connected to the terminals S and C. The heating relay 8 is turned on, and if the temperature as a result of heating exceeds, for example, 900°C, the heating relay 8 is turned off.

As shown in Fig. 3 and Fig. 4, the filter 2 is made of a linear ceramic body made by soaking polyurethane foam in ceramic slurry, pulling it up, drying it, and firing it. For example, recesses 2b in which a heat generating resistor 4 such as a sheathed type heater is buried are formed radially, and a thermocouple 5 is fixed at the center of the recesses 2b.

The present example configured as described above operates as described below.

When the mass main switch M8 is turned on and the engine is started, the optimal exhaust gas return amount is determined from the information obtained by the engine rotation speed sensor 1B, the engine coolant water temperature sensor 14, and the engine load sensor 15 by the EGGmllJ# installation. The corresponding EG valve 8
The negative pressure generated at the venturi part of the intake manifold 7 is applied to the diaphragm chamber of the nGm valve 8 by controlling the three-way solenoid 9 to determine the opening amount of the nGm valve 8.
Ru. Then, the nGm valve 8 is opened and the exhaust manifold 6
Exhaust gas BG discharged from the filter 2 is energized, and electricity is supplied to the extension filter 1, and the device 1 is activated. The IFh result,
If the temperature measured by the thermocouple 5 is lower than the preset F′ Lj this LIa
If it is less than m lf, the relay 8 is turned off,
The sequential filter 2 is heated. Then, as the filter 92 is heated by 4L, the filter 2 is affected by fko uJ retardant imitation sample j2! The flag of the burnt exhaust gas 183 is the same as the circle r.

8. In the second embodiment shown in FIGS. 5 and 6, the filter 2 is made of a spongy body of silicon carbide ceramic.
The filter 2 is formed so that the cross section is oriented in the opposite direction.
A vIt pole 2C is fixed to the opposite side, and a lead wire 2d is connected to ma2e.

Yojko, 2 yen filter contains 4 yen of heat sealed in an insulator.
The lead wire 15 is taken out and buried.

The filter 2 and electric m2C are covered on the outside with a heat-resistant and pressure-resistant material 2e and housed in a case 2f with a capacity of 4L.

The filter 2 constructed on this collar is made of silicon carbide material.
The ceramic is conductive, and the apparent resistivity using the X dimension of the linear body filter is about 0.51M/'', so if a voltage is applied to the electric wire, the ceramic itself generates heat and reaches a temperature of 900° C. or higher, so the combustible replica particles captured in Fill A are combusted.

In addition to the silicon carbide ceramic, the filter 2 may be made of other conductive ceramics, such as molybdenum disilicide (M
o8iz) It may be made of ceramic, and not only one formed into a spongy body but also one fired into a porous nicum structure may be used.

The other configurations and operations of the second embodiment described above are the same as those of the first embodiment.

The third embodiment shown in FIG. 6 uses a microcomputer as the tllJ control device l, which is also used as the E08 control bag 1i12.

In the figure, the input port of the 110 interface 20 of the microcomputer has 1! rA/L), f exchange fi
The thermocouple 5 set in the filter 2, the engine rotation speed sensor 1B, the engine cooling water temperature sensor 14/) 7, and the engine load sensor 15 are connected through the filter 2 through the cables 5a, ta&, 14a, and 15m, respectively. Seiho Kani/i) Hikyoki 5B, 1B&.

148.158 converted to digital ms by 11
0 interface 20. Reference numeral 21 denotes a central processing unit (et'u) which forms the core of the microcomputer, and performs each m arithmetic operation in synchronization with a clock pulse manually inputted from an external clock signal ordering circuit 21. And CPU21 is readOnly Aleznory
(tLOM) Control of signals input from the 110 interface 20 by the control program stored in the 22, output signals to be described later, processing of data, and tL
andom AccessMemory (KmukL
)28. Also c
A signal is sent from the Pu21 via the I10 interface 20 to operate the driver circuit 8a of the heating relay 8 that controls the energization of the heating resistor 4, and the driver circuit 9& of the three-way solenoid valve 9 that controls the AUM valve 8 mentioned above. is configured so that it is output.

The second embodiment configured on this sphere is controlled by a main routine control program shown in the general flowchart of FIG. To explain Fig. 8, first step 29 is to register CPU 21 yen, pay
B etc. are cleared, IL, necessary initial data, etc. are *S shown.

Step 80 shows processing for collecting information from each sensor 1B, 14.15.

The routine 31 determines the return direction of the exhaust gas EG based on the information collected from each sensor 18, 14, 15, and outputs a signal to control the three-way solenoid valve 9 which controls the opening of the guh valve 8. Indicates a process consisting of steps.

Step 82 is the routine 81 where the kJGli valve 8
It is determined whether or not it has been opened, and if it has not been opened yet, the process returns to step 80, and if it has been opened, the process moves to the next routine 8B.

The routine 88 performs a process consisting of steps 4) to combust the carbon trapped in the filter 2 as the exhaust gas EG is returned; and 4) to control the width.

The control program consisting of such steps and routines is executed in step 29 when the main switch M8 is turned on and the CI'L121 is energized to start the engine.
The register RAM M2O in U21 is initialized, and then in step 30 the information from the valley processor 18.14.15 is stored in the CPU, and in routine 81 the processing necessary for returning the exhaust gas EG is performed. As a result, the opening heel of the JR valve 8 is controlled to an appropriate value of E (m), and at this time, the exhaust gas k is
If Ju is returned or stopped, there is no need to heat the filter, so the process jumps to step 30, and if the valve 8 is open, a routine 88 is performed in which the exhaust gas E (exhaust gas EG When the carbon is returned, the filter 2 is heated to burn the carbon trapped in the filter 2, and a process is performed to prevent the filter 2 from clogging.

In detail, the filter heating routine indicated by routine 38 is processed by the program shown in the flowchart of FIG.

To explain the valley step of this flowchart, step 880 is the address of the original program when jumping to this routine, that is, the content of the program counter of CPU 21 yen is transferred as it is to the stack pointer in 0P021, and then this routine 88 The process of manually inputting the first program address to the program counter is shown.

Step 881 shows the process of manually measuring the temperature of the filter 2 using the thermocouple 5 fixed to the filter 2 and storing it in a predetermined location in the RAM.

Step 882 indicates a process of determining whether the temperature read in step 381 is, for example, 500° C. or higher, and branching the program based on the result.

In step 833, the heating relay 8 is turned on and the filter 2 is turned on.
This shows the process of heating.

Step 834 skips the process of incrementing the counter CT provided in the RAM 2B, which is a soft timer.

Step d85 is a process of determining whether the counter C'l' has reached a predetermined value N, that is, whether the filter 2 has been heated for a predetermined time or more. If so, go to Moehi Temple! The process of activating an alarm device (not shown) assuming that there is an A-connection is shown.

Step 337 indicates that the temperature of filter 2 is above @value, for example 9.
The process of determining whether the temperature is 00°C or higher or apricot is reduced.

Step 888 shows a process of turning off the heating relay 8 and stopping heating of the filter 2.

Step 389 is the counter C which is the soft timer.
The process of resetting T is shown.

Step 840 shows a process of changing the contents of the program counter used in this routine to the contents stored in the stack pointer in step 880 and jumping to the main routine shown in FIG.

Filter heating routine 3 consisting of such steps
If we explain the program in step 8 according to its flow, the program that jumps from the main routine will start at step 88.
After storing the address to return to after processing nT of this routine 38 in the stack pointer at 0, the filter temperature is manually set at step 881, and it is determined whether the filter temperature is 50U°C or higher at step 882. If so (the temperature is 500°C or less immediately after the start), the combustible particulates captured by the filter 2 have not reached the temperature at which they are burned, so the process moves to step 888 to heat the filter 2, and the counter CT is incremented in step 884. Then, in step 385, it is determined whether the predetermined heating time, that is, the value of the counter CT has reached N or more, and if it is less than N, the process proceeds to step 8.
The process moves to a process for jumping to the main routine shown at 40, and if it is N or more, an alarm device for notifying an abnormality is activated, and then the process moves to step 840.

If the filter 2 has already been heated, in step 882, if the filter temperature is 50°C or higher, it is determined that the combustible W1 particles captured by the filter 2 are being burned due to the heating of the filter 2, and the stay is stopped. If the filter 2 is heated to a temperature higher than 900°C, the combustible particulates will self-combust due to their heat resistance, so step 888 turns off the output of the heating relay 3. Then, in step 889, the counter is reset, and the process moves to C step 840. In addition, in order to burn particles with a 71 buJ g value at temperatures above 900°C, JII heat from the filter 2 is still required, so instead of proceeding to step 338 where the heating relay 3 is turned off, the process proceeds to step 834. The process described above is performed.

In this smart routine 83, the I captured by the filter 2 is
The JJm function is controlled to heat the filter 2 until it reaches the temperature required for combustion of particles, and to stop heating the filter 2 when the temperature of the filter 2 reaches that temperature, and also instructs heating for a predetermined period of time. If the filter temperature does not rise even after the signal is output, it is determined that there is something wrong with the electrical system, such as a disconnection, and control is performed to issue an alarm.

As explained above, the exhaust gas system for a diesel engine of the present invention includes a filter that captures combustible particles provided in the exhaust gas recirculation flow path from the exhaust pipe to the intake pipe, and a heating resistor that heats the filter. and an energization control device that controls energization to the heating resistor so as to sequentially burn the combustible particulates captured by the filter.

Therefore, according to the present invention, the combustible particulates captured in the filter provided in the flow path of the EGfL are sequentially combusted, so that the filter can be prevented from clogging even with low power consumption, and the exhaust gas can be smoothly discharged at all times. Reflux can be carried out, and as with the conventional method of simultaneously burning and removing large amounts of combustible particles that have accumulated in the filter, the intake temperature may rise abnormally or flammable particles that have accumulated in the filter may be removed. This has the effect of advantageously solving the problem that the original performance of the EGJL system cannot be brought out due to variations in the amount of exhaust gas returned due to particulates.Also, the energization control device can be controlled manually by a temperature detection sensor fixed to the filter. If controlled by a signal, it will not heat up more than necessary, prevent wasteful power consumption of the heating resistor, and stop exhaust gas from flowing based on information from the engine status sensor #I8 In addition, if the heat resistance to the heat generating resistor is reduced to medium, unnecessary gravity consumption of the heat generating resistor can be prevented.Furthermore, if the heat generating resistor is also used as a filter made of conductive material, a separate heat generating resistor storage can be used. It has many advantages such as the structure becomes simpler without the need to provide a.

[Brief explanation of drawings]

Diagram 1 is the first part of the exhaust gas purification system for Honkomei diesel engine.
FIG. 2 is a schematic diagram of the 15th embodiment; FIG. 2 is a circuit diagram of the control device; FIGS. 8 and 4 are cross-sectional diagrams of four filters; '7
FIG. 7 is a block diagram showing the second embodiment, and FIGS. 8 and 9 are flow charts showing the control program. 1... Energization control device 2...
...Filter 4...Heating resistor
5・・・・・・・・・;・Thermocouple 5a, 18&, 1
4a, 15a-・-・・-A/i) Transformer 20...
...l/U interface 21 ...
・Of'U agent Patent attorney Tsutomu Adachi Figure 1 Figure 2 Figure 9 Procedure correction teeth (voluntary) 1, 8 indications 1982 Patent Application No. 197197 2 Title of the invention I ゛ Easel engine exhaust gas Purification device 3, relationship with the person making the correction Patent applicant address 14-18 Tsuji-cho, Mizuho-ku, Nagoya @ Name (454) NGK Spark Plug Co., Ltd. Representative Osamu Ogawa 4 , Agent 〒460 5, Date of Supplementary 1F Order Voluntary

Claims (1)

[Scope of Claims] L. A filter for trapping 1!1:111 particles installed in the exhaust gas recirculation pipe from Hikito to Kikese, and L.
A heating resistor for heating the filter, and an energization example 141 for controlling energization to the heating resistor so as to sequentially burn the A3 flammability imitating particles captured by the filter. Exhaust gas purification equipment for diesel engines. 2. The energizing device 1141 is an Igl device that is equipped with a temperature detection function and controls the energization to the heating resistor based on the output of the sensor. Engine exhaust gas purification device. a. The am+t11 control device is equipped with an engine status sensor and controls energization to the heating resistor based on the output of the sensor. Purification device. 4. The heating resistor is a filter itself made of a conductive material. 1. The exhaust gas device of a diesel engine according to claim 1. 5. The conductive material is a silicon carbide wire or a silicon wire. Claim 4 Exhaust gas purification W71m made of molybdenum ceramic.