JPS6193222A - Exhaust accumulation purger in diesel particulate oxidizer system - Google Patents

Abstract

PURPOSE:To make an exhaust accumulation heaped up on an exhaust pressure detecting pipe line purgeable to an exhaust passage, by feeding compressed air to an exhaust pressure detecting exhaust pipe via a check valve. CONSTITUTION:A pressure sensor 10 detects exhaust pressure in an exhaust system of a Diesel engine provided with a Diesel particulate oxidizer (DPO) 5 through exhaust pressure detecting pipe lines 94 and 94'. Compressed air is fed to these exhaust pressure detecting pipe lines 94 and 94' from a compressed air feeding device 82 via a check valve 96. In a compressed air feeding pipe line 95, there is provided with a compressed air feed controlling device MP which controls feed of the compressed air. In this connection, a purge mechanism PM is controlled by a control part ECU.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a purge device for cleaning diesel particulates accumulated in exhaust pressure detection piping in a diesel particulate oxidizer system.

Diesel engine exhaust contains particulates, which are flammable, fine carbonized compounds, and are the main cause of black smoke in the exhaust gas. These particulates spontaneously ignite and burn when the exhaust gas temperature exceeds 1, for example, 500°C, when the vehicle is running at high speed and under high load (hereinafter referred to as "self-combustion"), but when the temperature does not reach 500°C, such as during steady driving or idling. etc. (accounting for more than 90% of vehicle driving).

It is released directly into the atmosphere.

However, since particulates may be harmful to the human body, in recent years there has been much research into diesel particulate oxidizers (hereinafter sometimes referred to as rDPOJ), which are installed in the exhaust passage of vehicle diesel engines.

By the way, this DPO has a tendency to collect and accumulate particulates and block the exhaust passage when used.
In order to regenerate PO, research is also underway on mechanisms that promote regenerative combustion of particulates.

Such regeneration auxiliary mechanisms include, for example, retarding the fuel injection timing, throttling the intake air, and increasing the amount of exhaust gas recirculation.
It is undesirable to operate the regeneration assist mechanism for a long period of time, as this will worsen the feeling and reduce fuel consumption.

Therefore, in a conventional diesel particulate oxidizer system, a pressure sensor may be used to detect the exhaust pressure in the upstream exhaust passage of the DPO in order to start or stop the operation of the regeneration assist mechanism.

However, with such exhaust pressure detection means for diesel engines, water vapor, soot, SOx, etc. present in the exhaust gas accumulate in the exhaust pressure detection piping or the water trap installed in the exhaust pressure detection piping. In cold regions, there are problems such as water freezing, and there are also problems such as soot clogging, which makes it impossible to detect exhaust pressure or cannot detect it accurately, resulting in transmission delays. This results in a decrease in pressure sensor performance and also in durability.

The present invention aims to solve these problems,
The exhaust deposits accumulated in the exhaust pressure detection piping connecting the exhaust passage and the exhaust pressure detection sensor can be purged into the exhaust passage. An object of the present invention is to provide an exhaust deposit purging device in a diesel particulate oxidizer system.

The exhaust deposit purging device of the present invention is used in a diesel particulate oxidizer system that detects the exhaust pressure of the exhaust system of a diesel engine equipped with a diesel particulate oxidizer using a pressure sensor through exhaust pressure detection piping. a compressed air supply means for supplying compressed air, a compressed air supply pipe for supplying compressed air from the compressed air supply means to the exhaust pressure detection pipe via a check valve, and the exhaust pressure detection through the compressed air supply pipe. The compressed air supply control means controls the supply of compressed air sent to the commercial piping, and the purge mechanism control section controls the operation timing of the compressed air supply control means.

In the purge mechanism control section, when the compressed air supply timing is detected, the purge mechanism control section supplies a control signal to the compressed air supply control means, and from the compressed air supply means passes the compressed air supply piping to detect exhaust pressure. Purge compressed air is sent to the pipe, and exhaust deposits accumulated in the exhaust pressure detection pipe are returned to the exhaust passage and removed.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
1 to 10 show a diesel particulate oxidizer system equipped with a diesel engine exhaust deposit purging device as an embodiment of the present invention.
Its overall structure is a patent application filed in 1983-641 by one applicant.
The details are shown in the specification of No. 44. FIG. 1 is an overall configuration diagram of the purge device, FIG. 2 is an overall configuration diagram of the regeneration device, FIG. 3 is a block diagram thereof, FIG. 4 is a schematic configuration diagram showing the automatic timer of the VE type timer, Figure 5 is a hydraulic system diagram, Figures 6 (a) and (b) are a sectional view and schematic diagram showing the main body of the filter device, Figure 7 is a graph showing its action, and Figure 8 is its required advance angle. Characteristic(
Graph for explaining required fuel injection timing characteristics), No. 9
The figure is a graph showing the relationship between the amount of particulates accumulated in the DPO, the main muffler pressure loss, and the DPO pressure loss.
The figure is a graph showing the action of the purge device.

As shown in FIGS. 1 to 6, in one embodiment of the present invention, a diesel engine E has a built-in timer as a fuel injection timing adjustment means, which includes a solenoid timer ST as an on-off valve and a retard valve RV. A distribution type fuel injection pump 17 is provided, and this diesel engine E is
The cylinder block 1. The cylinder head 21 has a main chamber formed by a piston (not shown) and an auxiliary chamber (not shown) communicating with the main chamber formed in the cylinder head 2 .

Further, an intake passage 3 is connected to the main chamber of the diesel engine E via an intake valve (not shown), and an exhaust passage 4 is connected to the main chamber via an exhaust valve (not shown).
This exhaust passage 4 is equipped with a diesel particulate oxidizer (DPO) that captures particulates in the exhaust gas.
) 5 is interposed.

Note that particulates herein refer to combustible fine particles mainly composed of carbon and hydrocarbons.

Its diameter is about 0.3 μm on average, and it self-ignites at about 500°C or higher (350°C or higher in the presence of an oxidation catalyst).

In addition, as a trap carrier for this DPO5, a deep trap type heat-resistant ceramic foam with a catalyst phase containing platinum, palladium, or rhodium inside (this is two flat plates whose cross-sectional shape is oval, oblong, rectangular, etc.) is used as a trap carrier for DPO5. Hereinafter, this diesel particulate collecting member will be abbreviated as Kano 0 (diesel particulate oxidizer) as described above.

DPO5 communicates with the atmosphere via a muffler 6,
At all times (when not regenerating), exhaust gas from the engine E is received via the turbocharger 7 and the heat insulating pipe 8.

Exhaust pressure sensors 10 are attached to the inlet and outlet exhaust passages 4 of the DPO 5 via electromagnetic switching valves 78 and 79, which detect exhaust pressures at respective positions and output detection signals to the ECU 9, which will be described later.

Each of the electromagnetic valves 78 and 79 is a reproduction assisting mechanism control means and an on-off valve control means configured by a computer or the like.

A control signal from an electronic control unit (ECU) 9, which also serves as an operation end detection unit for the calculation unit 1 and a purge mechanism control unit, is received by the respective solenoids 78a and 79a, and the valve body 7
By controlling the suction of 8b and 79b, the valve body 79b
In the suction (open) state and the protruding (closed) state of the valve body 78b, the downstream (outlet) exhaust gas pressure P2 of the DPO5 is
In the suction (open) state and the protruding (closed) state of the valve body 79b, the upstream (inlet) exhaust gas pressure P□ of the DOP 5 is detected.Furthermore, an electromagnetic switching valve 77 is provided, and the ECU 9
The solenoid 77a receives a control signal from the valve body 77.
b is suction-controlled, atmospheric pressure (that is, pressure equal to the downstream pressure P of the muffler 6) is detected via the air filter 80 when the valve body 77b is in the suction (open) state. .

Further, the downstream (outlet) exhaust gas or the upstream (inlet) exhaust gas is passed through the solenoid valve 7 through exhaust pressure detection sensor filter devices 49a and 49b installed in the exhaust pressure detection piping 94, 94'.
8.79.

Two housings 92 of filter devices 49a, 49b
6(a),
As shown in (b), the exhaust passage side inlet 49c
From the exhaust pressure sensor side outlet 49d, there is a damping volume 8 for reducing exhaust pulsation, which has a built-in wire mesh 84.
3. First stage filter 85. Spacer 87. Second stage filters 86 are arranged in sequence.

Since the casing 49 is disposed at a distance from the exhaust passage 4, the wire mesh 84 is used to cool and condense water vapor in the exhaust gas and prevent moisture from entering the sensor diaphragm portion of the pressure sensor 10. , functions as a water trap (steam/water separator).

This wire mesh 84 is disposed in a space within the casing 49 that forms a damping volume 83 for reducing exhaust pulsation, and the damping volume 83 supplies exhaust gas with reduced exhaust pulsation to filters 85 and 86.

The filters 85 and 86 each include two PVF filter sections 85a and 86a and an AC-26 filter section 8.
5b.

86b, and the first stage filter 85 is SU
S plate 89 and FRM O-ring 88 and PBT
The second stage filter 86 is interposed between the spacer 87 and the FRM o-ring 88'. A hole 87 is provided in the center of the spacer 87.
a is open.

The volume 90.91 on the pressure sensor 10 side of each filter 85.86 is set as small as possible in order to reduce the amount of gas passing through the filter 85.86, and the volume 91 on the pressure sensor 10 side is set as small as possible to reduce the amount of gas passing through the filter 85.86. 94°94'
It communicates with the pressure sensor 10 through.

Pressure sensor 10 side volume 9 of each filter 85.86
The reason why 0 and 91 are set small is based on the following knowledge.

The amount of gas flowing into the filter 85.86 is due to exhaust pulsation, and when the exhaust pressure supplied to the filter 85.86 changes from (P-ΔP/2) to (P+ΔP/2), the amount of gas flowing into the filter 85.86 increases. The gas mass ΔG passing through .86 is as follows.

AG=G0-G-=(ΔPV)/RTThe deposition Δ■ (pressure P, gas temperature T) at this time is as follows.

ΔV=ΔGRT/P=(ΔP-V)/P Therefore, the gas flow rate due to exhaust pulsation is determined by the amplitude ΔP of the pulsation and the filter upstream volume (volume from the filter 85, 86 to the sensor diaphragm part) dead volume is ignored).

Furthermore, a purge machine iPM is provided as shown in FIG.
5, the compressed air supplied via the check valve 96 is controlled by an electromagnetic switching valve 76 serving as a compressed air supply piping, and the electromagnetic switching valve 76
The solenoid 76a receives a control signal from the ECU 9 to control the opening and closing of the valve body 76b, and when the purge mechanism PM is in operation, the electromagnetic switching valves 76 and 78 are opened and the filter device 49a is opened. Soot and moisture are purged from the filter 85 and wire mesh 84 to the exhaust passage 4.

Further, the electromagnetic switching valves 76 and 79 are opened, and soot and moisture are purged from the filter 85 of the filter device [49b] and the wire mesh 84 into the exhaust passage 4.

In addition, an exhaust passage 4 adjacent to the inlet (upstream) of the DPO 5
A temperature sensor (thermocouple) 14 is provided for detecting the DPO inlet exhaust gas temperature Tin.
The detection signal from 4 is input to the ECU 9.

Furthermore, a temperature/degree sensor (thermocouple) 15 is provided inside the DPO5 to detect the internal temperature Tf of the DPO5 (in particular, the filter bed temperature), and an outlet section of the DPO5 (
A temperature sensor (thermocouple) 16 for detecting the DrO output exhaust gas temperature TO is provided in the exhaust passage 4 adjacent to the downstream), and the detection signals from each of these temperature sensors 15 and 16 are input to the ECIJ9. .

The fuel injection pump 17 attached to the engine E is
The fuel injection timing can be adjusted by the fuel injection timing control means 18, which constitutes the regeneration assisting mechanism control means, which receives the control signal from the CU 9. An injection pump lever opening sensor (load sensor) 19 is attached to this injection pump 17,
Outputs the injection pump lever opening degree to the ECU 9.

Further, an engine rotation speed sensor 20 is provided as an engine state sensor that detects the rotation speed N of the engine E.

In the intake passage 3 formed by the intake manifold fixed to the engine E and the intake pipe that follows it.

An air cleaner, a compressor for the turbocharger 7, and an intake throttle valve 21 as intake negative pressure changing means are arranged in this order from the upstream side (atmospheric side).

The intake throttle valve 21 is driven to open and close by a diaphragm pressure response device 22. Pressure response device 2
2 is a pressure chamber 22c partitioned by a diaphragm 22b connected to a rod 22a that drives the intake throttle valve 21;
Atmospheric passage 24 that introduces atmospheric pressure Vat through air filter 23 and vacuum pressure Vv from vacuum pump 25
It is connected to a vacuum passage 26 that guides AC, and an electromagnetic switching valve 27 and an electromagnetic opening/closing valve 28 are interposed in these passages 24 and 26, respectively.

And the solenoid 27a, 2 of each electromagnetic valve 27.28
When a control signal based on duty control is supplied from the ECU 9 to the valve body 8a, each valve body 27b, 28b is suction-controlled, thereby reducing the negative pressure supplied to the pressure chamber 22c of the pressure responsive device 22. is adjusted and the rod 22
a is drawn in as appropriate, and the amount of throttle of the intake throttle valve 21 is controlled.

Further, one end of an EGR passage 29 for exhaust gas recirculation (hereinafter referred to as EGR) is opened in the intake passage 3 on the downstream side of the intake throttle valve 21 . Further, the other end of the EGR passage 29 opens on the downstream side of the exhaust manifold of the exhaust passage 4.

An EGR valve 30 constituting exhaust gas recirculation amount changing means is provided at the intake passage side opening of the EGR passage 29, and this EGR valve 30 is driven to open and close by a diaphragm type pressure response device 31. . Pressure response device 31
is in a pressure chamber 31c partitioned by a diaphragm 31b connected to a rod 31a that drives the EGR valve 30,
Atmospheric passage 33 that introduces atmospheric pressure Vat through air filter 32 and vacuum pressure Vv from vacuum pump 25
It is connected to a vacuum passage 34 that guides AC, and an electromagnetic switching valve 35 and an electromagnetic opening/closing valve 36 are interposed in these passages 33 and 34, respectively.

And the solenoid 35a, 3 of each solenoid valve 35.36
When a control signal based on duty control is supplied from the ECU 9 to the valve body 6a, the valve bodies 35b and 36b are suction-controlled, thereby reducing the negative pressure supplied to the pressure chamber 31c of the pressure-responsive device 31. is adjusted, rod 31
a is drawn in as appropriate, and the opening degree of the EGR valve 30 is controlled.

The opening of the intake throttle valve 21 is detected by a feedback signal to EuO3 from the intake throttle valve opening sensor 45 attached to the rod 22a, and the opening of the ERG valve 30 is detected by the rod 31a of the pressure response device 31. This is detected by a feedback signal to EuO3 from a position sensor 39 that detects the movement of EuO3.

When a control signal is supplied from the ECU 9 to the solenoid 37a of the electromagnetic valve 37, the valve body 37b is suction-controlled, thereby causing the water trap 4
Intake pressure downstream of the intake throttle valve 21 is supplied to the pressure sensor 38 through a passage 40 provided with a passage 9', and when the valve body 37b of the solenoid valve 37 protrudes, atmospheric pressure from the air filter 41 is supplied to the pressure sensor 38. be done.

Furthermore, the injection pump 17 is provided with a diaphragm pressure response device 46 as an idle-up actuator that constitutes an idle-up mechanism.

This pressure-responsive device 46 includes a diaphragm 46b connected to a rod 46a that drives an idle-up control section in the injection pump 17.
An electromagnetic on-off valve (hereinafter referred to as "electromagnetic valve" as necessary) 47 is connected to the pressure chamber 46c partitioned by the pressure chamber 6b. 48, and the air filter 48 and pressure chamber 46c are normally in communication.

When a control signal for duty control is supplied from the ECU 9 to the idle-up actuator control solenoid 47a of the solenoid valve 47, the valve body 47b is suction-controlled.
The pressure (negative pressure) supplied to the pressure chamber 46c of No. 6 is adjusted, the rod 46a is appropriately retracted, and the idle-up state (high-speed idle state) is controlled.

Further, fuel injection timing control means 18 is capable of regenerating the DPO 5 by combusting the particulates collected in the DPO 5 by supplying high temperature gas for particulate combustion containing oxygen gas from the diesel engine E to the DPO 5.
retards the fuel injection timing of the injection pump 17
It consists of a retard device that adjusts the angle.

Here, since the injection pump 17 is configured as a distribution type injection pump, the fuel injection timing control means 18 drives the timer piston with oil pressure (fuel pressure) from the hydraulic pump, and controls the relative relationship between the cam plate and the roller. A hydraulic automatic timer (internal timer) that moves the target position is used.

Note that the driver operates the accelerator pedal to increase the fuel injection amount to correct the decrease in output due to the delay in injection timing.

This hydraulic automatic timer is configured as a VE type timer, and is operated by the fuel pressure in the pump chamber 51 controlled by the regulating valve 50 as shown in Fig. 4.5. 52 is installed in the pump housing 53 so as to be perpendicular to the pump drive shaft 54, and this timer piston is moved by sliding in the timer housing 53 due to the balance between changes in the oil pressure and the spring force of the timer springs 55a and 55b. The movement of 52 can be converted into a movement of rotating a cylindrical roller ring 57 via a slide pin 56.

Then, the position of the rotor 57a attached to the roller ring 57 changes, and the timing of actuation of the plunger 63 by the cam plate changes.

The timer springs 55a and 55b are the timer piston 5
2 in the direction of injection delay, and as the engine speed increases, the fuel pressure in the pump chamber 51 increases, and the timer piston 52 is pushed overcoming the timer spring force, and the movement of the timer piston 52 causes the roller ring 57 to drive. The injection timing is advanced by rotating in a direction opposite to the rotational direction of the shaft.

The oil supplied from the chamber 51 becomes high pressure in the plunger 63 and is supplied to the fuel injection nozzle 65 via the de-reed valve 64.

Further, hydraulic passages 67a and 67b are provided which can communicate the high pressure chamber 73 and the low pressure chamber 74 of the timer piston 52, and the hydraulic passage 67a has a boat (opening/closing part) 59 for switching high advanced characteristics/middle advanced characteristics. A solenoid timer (opening/closing valve) ST equipped with a solenoid timer ST and a check valve 60 that improves the increase in oil pressure when starting the engine are installed, and a hydraulic passage 67a between the check valve 60 and the switching boat 59 has an overflow orifice 61. It communicates with the oil tank 62 via.

Further, oil is supplied from the oil tank 62 to the pump chamber 51 by a feed pump 58.

The main body of the solenoid timer ST has a check valve 60.
And an overflow orifice 61 is incorporated, and pressure oil is supplied from the pump chamber 51.

The check valve 60 is opened and the water is supplied to the switching boat 59.

When the control signal is not supplied to the solenoid of the solenoid timer ST (when off), the switching boat 59
middle advance commercial during partial)
When the control signal is supplied to the solenoid (
When the switch is on), the switching boat 59 is closed, resulting in high advance (H) characteristics.

The hydraulic passage 67b is provided with an orifice 66 and a retard valve RV as an on-off valve, and the retard valve RV receives a control signal from the ECU 9 and has a high advance (H) characteristic as shown in FIG. and low advance (L) characteristics.

As shown in FIG. 4.5, the timer piston 52 receives pressure oil from the pump chamber 51 into the high pressure chamber 73 via the oil passage 52a, and combines this oil pressure with the two springs 5 on the low pressure chamber 74 side.
5a and 55b, the position of the timer piston 52 is adjusted, and thereby the roller ring 57
is rotated to adjust the fuel injection timing.

That is, the stopper 7 fixed to the timer piston 52
A soft second timer spring 55b is interposed between the second timer spring 55b and the retainer 68, and the hydraulic pressure increased by starting the engine E is supplied to the high pressure chamber 73.

The timer piston 52 moves until the stopper 71 and the retainer 68 come into contact with each other, and as shown in FIG. 8, the fuel injection timing reaches 5° ATDC (After Top Dea).
th Center).

Then, as the oil pressure is increased appropriately by the load sensing timer mechanism according to the rotation speed of the engine E, the first
The timer spring 55a is compressed and the timer piston 5.2 moves to the left in FIG.

That is, the retainer 68 is slidably inserted into the rod 69, and the first timer spring 55a is in a compressed state and held between the retainer 68 and the shim 70, which are locked by the snap ring 69a. As shown by the symbol Ct in Fig. 8, the engine speed changes from N1 to N2 (
>Nl), the characteristic of constant injection timing can be obtained.

Note that the reference numeral 72 in FIG. 4 indicates an 0 ring.

In this way, when the reed valve RV is in the OFF (open) state, the fuel pressure becomes low through the passage 67b, so the pressure inside the high pressure chamber 73 becomes low regardless of the value of the engine speed, and the timer piston 52 is the first timer spring 5
5a and the second timer spring 55b to the right in FIG. 4, resulting in a low advance (full retard) position.

By the way, the time during which the fuel injection timing is retarded - the increase in the fuel injection amount per stroke of the fuel injection pump 17 to obtain the output ΔQ is determined by setting the retardation amount α, which significantly reduces the thermal efficiency of the engine E. As a result, the effective work of the engine E does not appear as an increase in the average effective pressure, but is released as heat loss.

In other words, the amount of heat corresponding to the total amount of fuel Q per stroke is the sum of the amount of work and heat loss, but here, by setting the retardation amount α, the amount of heat equivalent to the fuel increase amount ΔQ is completely reduced to heat loss. However, the increase in exhaust gas temperature due to such heat loss and the combustion heat generated by oxidation of incomplete combustion products by the catalyst on the DPO 5 increase the exhaust gas temperature.

Therefore, by delaying (retarding) the injection timing and simultaneously increasing the fuel injection amount as described above, the exhaust gas temperature at the same output operating point becomes higher and the DPO
Can burn particulates above 5, DP
O5 can be regenerated.

When the regeneration of the DPO 5 is completed, the ECU 9 outputs a signal to close the retard valve RV. At this time E
The CU 9 also outputs a signal for setting the intake throttle valve 21 to a predetermined opening degree.

When the retard valve RV closes, fuel pressure corresponding to the engine speed acts on the high pressure chamber 73.

Note that the reference numeral 42 in FIG. 3 indicates a vehicle speed sensor.
Reference numeral 43 indicates a clock, 44 indicates a temperature sensor for detecting the engine temperature (coolant temperature in this case) as an engine condition sensor, and 75 indicates a warning lamp as a warning light.

A diesel particulate oxidizer system equipped with an exhaust deposit purge device as an embodiment of the present invention is configured as described above. position).

First, the regeneration flag and the like are read, and the conditions under which the key was turned off in the previous operating state are read out from the memory.

As a result, if the regeneration flag is on, the injection timing and intake throttle amount are controlled.

DPO indicates whether playback control has been performed and playback has ended.
Judgment is based on the pressure loss of 5.

Furthermore, if the regeneration flag is off, normal injection timing control and EGR control are performed.

Then, the integrated value of diesel particulates and DPO
Based on the pressure loss, etc., it is detected whether it is time for regeneration.

Next, when the end of playback control is detected and after determining the playback time, it is determined whether the key is off, and if the key is on, processing starts again from turning on the playback flag. be done.

That is, during non-reproduction, each of the above-mentioned processing flows is executed, and a state of waiting for the reproduction flag to be turned on continues.

The reproduction start determination processing flow is a processing flow for determining the reproduction start time and turning on the reproduction flag.

First, by sending a control signal to the solenoid 79a,
With the valve body 79b open and the valve body 78b closed, the pressure P2 on the downstream side of the DPO 5 is detected by the pressure sensor 10. Furthermore, with the valve body 78a open and the valve body 79b closed, the pressure sensor 10 detects the pressure P2 on the downstream side of the DPO5. The pressure P1 on the upstream side of the DPO 5 is detected by lO, and the pressure sensor 10 detects the atmospheric pressure (approximately equal to the pressure on the downstream side of the muffler 6) po by opening the valve body 77b.

At this time, since the filter devices 49a and 49b appropriately reduce the pulsation of the exhaust pressure, variations in measured values are reduced, and accurate exhaust pressure can be detected.

The filter devices 49a* 49b prevent water, soot, etc. from entering the sensor diaphragm of the pressure sensor 10, so water accumulates in the sensor diaphragm, and in cold weather, this freezes and prevents the diaphragm from entering. This also solves the problem of parts being destroyed.

In addition, the purge mechanism PM allows moisture to be purged into the exhaust passage 4, which eliminates problems such as moisture accumulating in the slack portion of the detection line and freezing, preventing exhaust pressure from being detected, and problems such as delays in exhaust pressure transmission due to soot. can.

Further, the purge mechanism PM includes a compressed air supply means (compressor of the turbocharger 7) 8 as shown in FIG.
If the supercharging pressure from 2 is 1 greater than the upstream pressure of the DPO, it is considered to be a purgeable region, and the ECU 9 will, in principle, control the opening and closing of the solenoids 76a, 78a, and 79a as appropriate, but in the present invention, Since the check valve 96 is interposed in the compressed air supply pipe 95,
Even if the DPO upstream pressure P exceeds the supercharging pressure during purging, the exhaust gas will not flow back to the compressor side of the turbocharger 7.

Therefore, it is not necessary to specifically set the purgeable region as shown in FIG. 10, but stopping the purge in the high-load, high-speed region is an essential requirement due to the exhaust temperature. Therefore, a control signal for the purge mechanism PM from the ECU 9 is output based on, for example, the following conditions.

(1) Every time exhaust pressure is detected (before and after, etc.) (2) Every time or a certain distance traveled (3) At any time other than when exhaust pressure is detected, and by simultaneously opening the solenoids 76a, 78a, and 79a, the filter device 49a , 49b
At the same time, you can purge the exhaust deposits inside the solenoid 76.
a.

By alternately opening the solenoids 78a and 76a and 79a, exhaust deposits in the filter devices 49a and 49b are purged.

Then, the above-mentioned pressure P0. From Pi, P, main muffler pressure drop (p, -p,) and DPO pressure drop (p t -p z
), and as shown in FIG.
) is the boundary line corresponding to the loading amount of 70g in area C2.
When moving from to area C1, the playback flag is turned on.

When the weight is 70g or less, the regeneration flag is turned on when other integrated values are larger than the set value, and in other cases, the regeneration flag is maintained as it is. Instead of making the determination, it may be determined whether the DPO pressure loss P is equal to or higher than the regeneration start setting pressure.

In this case, one measurement value may be used as the DPO pressure drop P□, or in order to eliminate variations in measurement values, one may use the average value of many measurement values or one that has been subjected to other statistical processing. or

The regeneration end determination process flow is a process flow that determines the regeneration end time and turns off the regeneration flag, and is similar to the regeneration start determination process flow to determine the main muffler pressure loss (p
z po) and the DPO pressure loss (p x - P 2 ), and as shown in Figure 9, the main muffler pressure loss and the DPO pressure loss
For example, the regeneration flag is turned off when the pressure drop moves from the area C2 to the bizarre machine C1 at the boundary line corresponding to the loading amount of particulates (Pct) of 20 g, and in other cases, the regeneration flag remains as it is. be done.

The injection timing control processing flow is as shown in FIG.
The temperature T of P5, that is, the DPO inlet temperature Tin.

DPO internal temperature Tf or DPO outlet temperature T. is detected, and if this temperature T is 650°C or higher, it is determined that the temperature is abnormally high. Based on the abnormally high temperature map (Ne, θ), the temperature T is determined by the engine speed Ne and the pump lever opening θ. The injection timing is set as follows.

That is, this map for abnormally high temperatures is internally set with a fuel injection timing that is advanced compared to the map for normal driving.

If the temperature T is 650 degrees Celsius or lower, and the regeneration flag is off, the injection timing is set to be determined by the engine speed Ne and the pump lever opening degree θ according to the map (Ne, θ) during normal driving. .

If the playback flag is on, the playback map (Ne, θ
), the injection timing is set to be determined by the engine speed Ne and the pump lever opening degree θ.

By switching 5175 solenoids on and off to achieve these set fuel injection timings to obtain high advance characteristics or middle advance characteristics, and by slowly switching the retard valve RV using duty control, To obtain high advanced characteristics or full retard characteristics.

At the time of this switching, the valve control of the full retard solenoid timer ST has a variation range of 11 to 28 degrees, so
Sudden switching causes acceleration/deceleration shocks. In order to reduce the shock during this switching, solenoid timer ST
A sufficiently long time t0 seconds (for example,
2 to 3 seconds).

The switching of the solenoid timer ST by this duty control is controlled according to a region (zone) divided by the engine rotation speed and the lever opening degree, for example, when transitioning from near the maximum output characteristic to a low engine rotation speed region. In order to stabilize the idle, switching is performed quickly by on/off switching, and when transitioning from a retarded state to maximum output near the maximum output characteristic,
In order to reduce the shock, switching is performed slowly using duty control.

Note that the switching time t0 by duty control may be made a function of the engine rotation speed, or may be provided with time hysteresis. Moreover, each of the above-mentioned numerical values is an illustration.

According to a diesel particulate oxidizer system equipped with an exhaust gas deposit purge device as an embodiment of the present invention, the following effects or advantages can be obtained.

(1) Taking into consideration that the combustion speed increases as the exhaust temperature rises, the timing of the end of DPO combustion or the timing of the state in which combustion continues even if the operation of the regeneration assist mechanism is stopped is set earlier. Moreover, it can be detected accurately.

(2) It is possible to appropriately control the stoppage of the operation of the regeneration assisting mechanism based on the regeneration assisting mechanism stop timing detected in accordance with item 1 above.

(3) The wire mesh for the water trap can reliably trap moisture, thereby allowing exhaust gas from which moisture has been removed to be supplied to the pressure sensor.

(4) The exhaust pulsation reduction volume reduces exhaust pulsation, improves the detection accuracy of the pressure sensor, and further improves the durability of the filter and pressure sensor.

(5) The filter can also remove soot in the exhaust gas and moisture that could not be removed by the wire mesh.

(6) The addition of a purge system increases the flexibility of piping the exhaust pressure detection line.

(7) The exhaust pressure detection line can be purged using boost pressure while the engine is running.

As detailed above, the exhaust deposit purging device according to the present invention is a diesel particulate oxidizer that detects the exhaust pressure of the exhaust system of a diesel engine equipped with a diesel particulate oxidizer using a pressure sensor through an exhaust pressure detection pipe. Compressed air supply means for supplying compressed air, and compressed air supply piping for supplying the compressed air from the compressed air supply means to the exhaust pressure detection piping via a check valve, which is used in the system. and a compressed air supply control means for controlling the supply of compressed air sent to the exhaust pressure detection pipe through the compressed air supply pipe, and a purge mechanism control unit for controlling the operation timing of the compressed air control means. It is possible to obtain first-order effects or advantages with a simple structure.

(1) Exhaust deposits such as moisture and soot in the exhaust pressure detection piping can be returned to the exhaust passage and removed.

(2) According to item 1 above, in cold regions, moisture collected in slack parts of exhaust pressure detection piping and filter devices installed in the piping may freeze, causing the filter device and exhaust pressure The detection sensor can be prevented from being destroyed, and furthermore, the piping can be prevented from being clogged with ice or the like.

(3) According to item 1 above, soot can be removed, so the detection accuracy of the exhaust pressure detection sensor is improved.

(4) Since a check valve is interposed in the compressed air supply piping, backflow of exhaust gas during purging can be prevented.

Therefore, contamination of the filter device, solenoid valve, etc. can be suppressed, and setting of the purgeable region becomes unnecessary except for some high-load, high-speed regions, so that the software in the control section can be simplified.

[Brief explanation of drawings]

Figures 1 to 10 show a diesel particulate oxidizer system equipped with an exhaust deposit purge device as an embodiment of the present invention. Figure 1 is an overall configuration diagram of the purge device, and Figure 2 is its Overall configuration diagram of the playback device, Part 3
The figure is a block diagram, Figure 4 is a schematic configuration diagram showing the automatic timer of the VE type timer, Figure 5 is a hydraulic system diagram, and Figures 6 (a) and (b) are the main bodies of each filter device. A cross-sectional view and a schematic diagram, Fig. 7 is a graph showing its effect, Fig. 8 is a graph for explaining its required advance angle characteristics (required fuel injection timing characteristics), and Fig. 9 is a graph showing particulates deposited on the DPO. Figure 1O is a graph showing the relationship between the main muffler pressure loss and the DPO pressure loss. 1... Cylinder block, 2... Cylinder head,
3... Intake passage, 4... Exhaust passage, 5... Deep collection type diesel particulate oxidizer (DPO)
) 6...Muffler, 7...Turbocharger-18.
...Heat insulation pipe, 9...Electronic control unit (ECU) that also serves as a regeneration auxiliary mechanism control means, an on-off valve control means, a calculation unit 2 operation end detection section and a purge mechanism control section, 10...As an exhaust pressure detection sensor pressure sensor, 13...air filter, 14-16...temperature sensor, 17...distribution type fuel injection pump as fuel injection timing adjustment means, 18...
Fuel injection timing control means constituting the regeneration auxiliary mechanism control means, 19... Injection pump lever opening sensor (load sensor) as an engine condition sensor, 20... Engine rotation speed sensor as an engine condition sensor, 21. ...Intake throttle valve as intake negative pressure changing means, 22...Pressure response device, 22a...Rod, 22b...Diaphragm, 22c...Pressure chamber, 23...Air filter, 2
4... Atmospheric passage, 25... Vacuum pump, 26
...Vacuum passage, 27...Solenoid valve, 27a, 2
8a... Solenoid, 27b, 28b... Valve body, 2
9... EGR passage, 30... EGR valve constituting exhaust gas recirculation amount changing means, 31... Pressure response device, 31a
...Rod, 31b...Diaphragm, 31c...
・Pressure chamber, 32...Air filter, 33...Atmospheric passage, 33...Vacuum passage, 35-37...Solenoid valve, 35aL36at37a...Solenoid, 35b
, 36b, 3'7b e+-valve body, 3g-・pressure sensor, 39... position sensor, 40... passage. 41... Air filter, 42... Vehicle speed sensor, 43
...Clock, 44...Water temperature sensor as engine condition sensor, 45...Intake throttle valve opening sensor, 46
...Idle up actuator constituting the idle up mechanism, 46a... Mouth, Rad, 46b... Diaphragm. 46c...Pressure chamber, 47...Solenoid valve, 47a...
Solenoid, 47b...valve body, 48...air filter, 49...casing, 49'...water trap, 49a, 49b...filter device for exhaust pressure detection sensor, 49c...exhaust passage Side inlet, 49d... Pressure sensor side outlet, 50... Regulating valve, 51... Pump chamber, 52... Timer piston, 5
2a... Oil path, 53... Pump housing, 54...
...Pump drive shaft, 55a...First timer spring, 55b...Second timer spring, 56
...Slide pin, 57...Roller ring, 57a
...Roller, 58...Feed pump, 59...
High advanced characteristic/middle advanced characteristic switching port (opening/closing part), 60...Check valve, 61...
Overflow orifice, 62...oil tank,
63...Plunger, 64...Delivery valve, 6
5... Fuel injection nozzle, 66... Orifice, 67
a, 67b... Hydraulic passage, 68... Retainer, 69
...Rod, 69a...Snap spring, 70
...Shim, 71...Stopper, 72...0 ring, 73...High pressure chamber, 74...Low pressure chamber, 75...Warning lamp, 76-79...Solenoid switching valve ,7
6a-79a... Solenoid, 76b-79b...
Valve body, 80... Air filter, 81... Solenoid switching valve, 81a... Solenoid, 81b... Valve body, 82
... Compressed air supply means, 83 ... Damping volume for reducing exhaust pulsation, 84 ... Wire mesh, 85
...First stage filter, 85a...PVF filter section, 85b...AC-26 filter section, 86...
・Second stage filter, 86a...PVF filter part, 86b...AC-26 filter part, 87...Spacer, 87a'' hole, 88.8g'---FRM 0
Ring, 89---5 LIS plate, 90, ■...
・Pressure sensor side volume, 92.93... Housing, 94.94'... Piping for exhaust pressure detection, 95... Piping for compressed air supply, 96... Check valve, E...
- Diesel engine, MP... compressed air supply control means, PM... purge mechanism, RV... retard valve as an on-off valve, ST... solenoid timer as an on-off valve. Figure 6 (Q) (b) Side 6 figure Figure 9 Mail muffler or 1 negative (mre l-13) -%10 figure

Claims (1)

[Claims] In a diesel particulate oxidizer system that detects exhaust pressure in an exhaust system of a diesel engine equipped with a diesel particulate oxidizer using a pressure sensor through exhaust pressure detection piping, a compressed air supply means for supplying compressed air; A compressed air supply pipe that supplies compressed air from a supply means to the exhaust pressure detection pipe via a check valve, and a supply of compressed air sent to the exhaust pressure detection pipe through the compressed air supply pipe is controlled. What is claimed is: 1. An exhaust deposit purge device comprising: compressed air supply control means for controlling the compressed air supply; and a purge mechanism control section for controlling the operating timing of the compressed air supply control means.