JPH0429848B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a purging device for diesel particulate deposited in exhaust pressure detection piping connected to the exhaust system of a diesel engine, and in particular to a device for purging diesel particulate accumulated in exhaust pressure detection piping connected to the exhaust system of a diesel engine. The present invention relates to a device for purging exhaust gas deposits deposited on a filter device for an exhaust pressure detection sensor connected to a system.

[Conventional technology]

Diesel engine exhaust contains particulate, a combustible, fine carbonized compound, which is the main cause of black smoke in the exhaust gas. This particulate will spontaneously ignite and burn when the exhaust gas temperature reaches, for example, 500°C or higher 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 during steady driving or idling. etc. (accounting for over 90% of vehicle operation), it is released directly into the atmosphere.

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

By the way, as this DPO is used, it tends to collect and deposit particulate ylate and block the exhaust passage, so research is being actively conducted on a mechanism that promotes the re-combustion of particulate ylate in order to regenerate this DPO.

Such regeneration auxiliary mechanisms include, for example, retarding the fuel injection timing, throttling the intake air, and increasing the amount of exhaust gas recirculation, but during this regeneration period, the feeling deteriorates and the fuel efficiency decreases. It is undesirable to operate the regeneration assisting mechanism for a long period of time, as this will lead to deterioration.

Therefore, in the conventional diesel particulate oxidizer regeneration device, in order to start or stop the operation of the regeneration auxiliary mechanism,
An exhaust pressure detection sensor is used to detect the exhaust pressure in the upstream exhaust passage of the DPO.

[Problem to be solved by the invention]

However, with conventional diesel engine exhaust pressure detection sensors, water vapor, soot, _SO
In addition, in cold regions, there are problems such as water freezing, and furthermore, there are problems such as soot clogging, which makes it impossible to detect exhaust pressure or accurately detect it. When a transmission delay occurs, not only the performance of the pressure sensor deteriorates, but also the durability of the sensor deteriorates.

Therefore, in a diesel engine equipped with a supercharger, it is possible to recirculate the exhaust deposits accumulated in the water trap etc. to the exhaust pipe side using the differential pressure between the boost pressure from the supercharger and the exhaust pressure of the exhaust pipe. However, in general, when the boost pressure is high, the exhaust pressure is high, and when the boost pressure is low, the exhaust pressure is also low, so the differential pressure between the boost pressure and the exhaust pressure cannot be kept large enough, so the purgeable area is The problem is that it is narrow.

Furthermore, in the purging means using supercharging pressure, oil components may adhere due to blow-by gas.

The present invention aims to solve such problems by interposing a filter device in the exhaust pressure detection piping that connects the exhaust passage and the exhaust pressure detection sensor, and also by installing a filter device in the exhaust pressure detection pipe that connects the exhaust passage and the exhaust pressure detection sensor. An object of the present invention is to provide an exhaust deposit purging device for a filter device for an exhaust pressure detection sensor in a diesel engine, which is capable of purging exhaust deposits such as particulate matter and moisture into the intake system of the engine.

[Means to solve the problem]

Therefore, the exhaust deposit purge device of the filter device for the exhaust pressure detection sensor in the diesel engine of the present invention is applied to the exhaust pressure detection piping that connects the exhaust passage and the exhaust pressure detection sensor in the exhaust system of the diesel engine. An interposed filter device for an exhaust pressure detection sensor, an atmospheric control valve that controls communication of the piping on the sensor side of the filter device to the atmosphere, and a control valve that connects the piping on the exhaust passage side of the filter device to the air intake of the engine. a suction pipe communicating downstream of the throttle valve; a suction control valve for switching and controlling whether the exhaust passage side of the filter device communicates with the exhaust passage or the suction pipe; and the atmospheric control valve. and a purge control section that switches between the suction control valve and the intake throttle valve, and sends air to the engine via the atmospheric control valve so that the deposits in the filter device are returned to the downstream side of the intake throttle valve and removed. It is characterized by

[Effect]

In the exhaust deposit purging device for a filter device for an exhaust pressure detection sensor in a diesel engine according to the present invention, the suction pipe is connected downstream of the intake throttle valve, and when the filter device is purged, the intake throttle valve is closed to generate a powerful Since a suction force can be generated, exhaust gas deposits accumulated on the filter device can be reliably removed to the intake system within a short period of time.

As a result, purging of the filter system can be accomplished without the regeneration system of the diesel particulate oxidizer being inoperable for an extended period of time.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Figures 1 to 10 show a diesel particulate oxidizer equipped with a purge device for regenerating exhaust deposits from a diesel engine with a supercharger as an embodiment of the present invention. Fig. 1 shows the overall configuration of the purge device, Fig. 2 shows the overall configuration of the regeneration device, Fig. 3 shows the block diagram, and Fig. 4 shows the automatic timer of the VE type timer. 5 is a hydraulic system diagram, 6a and 6b are sectional views and schematic diagrams showing the respective filter device bodies, 7 is a graph showing its operation, and 8 is a diagram of its hydraulic system. A graph to explain the required advance angle characteristics (required fuel injection timing characteristics), Figure 9 is a graph showing the relationship between the particulate amount accumulated in the DPO, the main muffler pressure loss and the DPO pressure loss, and Figure 10 is the suction control valve. FIG.

As shown in FIGS. 1 to 6, the diesel engine E is provided with a distribution type fuel injection pump 17 as a fuel injection timing adjustment means, which has a built-in timer equipped with a solenoid timer ST as an on-off valve and a retard valve RV. This diesel engine E has a main chamber 8 formed by the cylinder block 1, cylinder head 2, and piston 82.
1 and the cylinder head 2, and an auxiliary chamber (not shown) that communicates with the main chamber 81 is provided.

Further, the main chamber 81 of the diesel engine E is connected to the intake passage 3 and an air filter 98 via an intake valve 96, and is also connected to the exhaust passage 4 via an exhaust valve 97. A diesel particulate oxidizer (DPO) 5 is installed to capture particulate in the exhaust gas.

Note that particulates here refer to flammable fine particles mainly composed of carbon and hydrocarbons, which have an average diameter of about 0.3 μm and self-ignite at temperatures of approximately 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-trapping type heat-resistant ceramic foam with a catalyst containing platinum, palladium, or rhodium inside (this is two flat plates whose cross-sectional shape is oval, oblong, or rectangular) is used. Hereinafter, this diesel particulate collection member will be used as DPO as described above.
It is abbreviated as (diesel particulate oxidizer).

The DPO 5 communicates with the atmosphere via a muffler 6, and always receives exhaust gas from the engine E via a turbocharger 7 and a heat insulating pipe 8 (when not regenerating).

In the exhaust passage 4 on the inflow and outflow side of the DPO 5, an exhaust pressure sensor 10 that detects the exhaust pressure at each position and outputs a detection signal to the ECU 9, which will be described later, is installed. 7
8,79.

Each electromagnetic valve 78, 79 is operated by an electronic control unit (ECU) 9 which also functions as a regeneration auxiliary mechanism control means, an on-off valve control means, an arithmetic section, an operation end detection section, and a purge mechanism control section, which is composed of a computer or the like. Control signals are sent to the respective solenoids 78a and 79a.
When the valve body 79b is in the suction (open) state and the valve body 78b is in the protrusion (closed) state, the downstream (outlet) exhaust gas pressure P ₂ of the DPO 5 is When the body 78b is in the suction (open) state and the valve body 79b is in the protruding (closed) state,
The upstream (inlet) exhaust gas pressure _P1 of DPO5 is detected.

Furthermore, an electromagnetic switching valve 77 is provided,
When the solenoid 77a receives a control signal from the ECU 9 and controls the valve body 77b to attract air, the air filter 80
It communicates with the atmosphere through the muffler 6 to detect atmospheric pressure (that is, a pressure equal to the downstream pressure P ₀ of the muffler 6).

Also, downstream (outlet) exhaust gas or upstream (inlet)
Exhaust gas is detected through exhaust pressure detection piping 94a, 94b, 9
It is supplied to electromagnetic valves 78 and 79 via electromagnetic valve 76 and exhaust pressure detection sensor filter devices 49a and 49b, which are installed in 4'a and 94'b.

The solenoid valve 76 is configured as a rotary valve, and is always in communication with the pipes 94a and 94b as shown in FIG.
The communication state is maintained, and the exhaust pressure is detected (this state is hereinafter referred to as the "off state").

Also, the solenoid 76a of the solenoid valve 76 is connected to the ECU.
When a control signal is received from 9, the solenoid valve 76
As shown in FIG. 10, the pipe 94b and the suction pipe 95 are in communication with each other, and the pipe 94'b and the suction pipe 95 are in communication with each other, and exhaust deposits are sucked into the intake system. (This state is hereinafter referred to as the "on state").

This suction pipe 95 is connected to the intake passage 3 downstream of the intake throttle valve 21 .

In the casing 49 consisting of the two housings 92 and 93 of the filter devices 49a and 49b, as shown in FIGS. 6a and 6b, there is a wire mesh 84 extending from the exhaust passage side inlet 49c to the exhaust pressure sensor side outlet 49d. Exhaust pulsation reduction dipping volume 83 with built-in, first stage filter 85, spacer 87, second stage filter 86
are arranged in order.

Since the wire mesh 84 has the casing 49 located away from the exhaust passage 4,
The water vapor in the exhaust gas is cooled and condensed, and the pressure sensor 10
This is to prevent moisture from entering the sensor diaphragm, and functions as a water trap (steam/water separator).

This wire mesh 84 is attached to the casing 4 forming the damping volume 83 for reducing exhaust pulsation.
The damping volume 83 supplies exhaust gas with reduced exhaust pulsation to the filters 85 and 86.

Filters 85 and 86 are each two PVFs.
It consists of filter parts 85a and 86a made of aluminum and filter parts 85b and 86b made of AC-26.The first stage filter 85 is made of a plate 89 made of SUS and
The second stage filter 86 is interposed between the FRM O-ring 88 and the PBTB spacer 87, and the second stage filter 86 is interposed between the spacer 87 and the FRM O-ring 88'. A hole 87a is provided in the center of the spacer 87.
is open.

Note that the pressure sensor 10 of each filter 85, 86
The side volumes 90 and 91 are filters 85 and 86.
In order to reduce the amount of gas passing through, the volume 91 on the pressure sensor 10 side is set to be as small as possible, and the volume 91 on the pressure sensor 10 side communicates with the pressure sensor 10 through exhaust pressure detection piping 94b, 94'b.

The pressure sensor 10 side volumes 90 and 91 of each filter 85 and 86 are set small based on the following knowledge.

The amount of gas flowing into the filters 85, 86 is due to exhaust pulsation, and the exhaust pressure supplied to the filters 85, 86 changes from (P-ΔP/2) to (P+ΔP/2).
2), the gas mass ΔG passing through the filters 85 and 86 is as follows.

ΔG=G ₊ −G _- = (ΔP・V)/RT At this time, the volume ΔV (pressure P, gas temperature T) is
It will look like this:

ΔV=ΔGRT/P=(ΔP・V)/P Therefore, the gas flow rate caused by exhaust pulsation is determined by the pulsation amplitude ΔP and the filter upstream volume (volume from filters 85 and 86 to the sensor diaphragm section) V( (Ignore sensor dead volume)
is proportional to the product of

Furthermore, a purge mechanism PM is constituted by the electromagnetic switching valve 76 as the suction control valve described above and the suction piping 95, and when the purge mechanism PM is operated, the electromagnetic switching valve 76 controls the suction as shown in FIG. state, and the electromagnetic switching valves 77 to 79 are opened,
Soot and moisture are purged into the intake passage 3 from the filter 85 and wire mesh 84 of the filter device 49a and the filter 85 and wire mesh 84 of the filter device 49b.

When the purge mechanism PM operates, the intake throttle valve 21 is throttled, and the atmosphere (suction air) from the filter 80 is sucked by the suction action of the diesel engine E, thereby removing exhaust deposits from the intake passage 3. It is then purged.

Note that the electromagnetic switching valves 78 and 79 may be opened separately.

Furthermore, a temperature sensor (thermocouple) 14 for detecting the DPO inlet exhaust gas temperature Tin is provided in the exhaust passage 4 close to the inlet (upstream) of the DPO 5, and a detection signal from this temperature sensor 14 is input to the ECU 9. be done.

Furthermore, the internal temperature of DPO5 is
A temperature sensor (thermocouple) 15 for detecting the temperature of the filter bed (in particular, the filter bed temperature) is provided at Tf, and a temperature sensor (thermocouple) for detecting the DPO outlet exhaust gas temperature To is provided in the exhaust passage 4 adjacent to the outlet (downstream) of the DPO5. pair) 16 are provided, and the detection signals from each of these temperature sensors 15 and 16 are
Input to ECU9.

Fuel injection pump 1 attached to engine E
Reference numeral 7 indicates fuel injection timing control means 1 constituting a regeneration assisting mechanism control means that receives a control signal from the ECU 9.
8 allows the fuel injection timing to be adjusted. An injection pump lever opening sensor (load sensor) 19 is attached to the injection pump 17 and outputs the injection pump lever opening to the ECU 9.

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

In the intake passage 3 formed by the intake manifold fixed to the engine E and the intake pipe following this,
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.
The pressure response device 22 includes an atmospheric passage 24 that introduces atmospheric pressure Vat through an air filter 23 into a pressure chamber 22c partitioned by a diaphragm 22b connected to a rod 22a that drives an intake throttle valve 21, and a vacuum passage 24 that introduces atmospheric pressure Vat from a vacuum pump 25. A vacuum passage 26 for guiding the pressure Vvac is connected thereto, and an electromagnetic switching valve 27 and an electromagnetic on-off valve 28 are interposed in these passages 24 and 26, respectively.

And the solenoid 27 of each electromagnetic valve 27, 28
When a control signal by duty control is supplied from the ECU 9 to a, 28a, each valve body 27b, 28
b is controlled by suction, thereby adjusting the negative pressure supplied to the pressure chamber 22c of the pressure response device 22, and drawing the rod 22a appropriately to control the amount of throttle of the intake throttle valve 21. be done.

In addition, the intake passage 3 on the downstream side of the intake throttle valve 21 is provided with a valve for exhaust gas recirculation (hereinafter referred to as EGR).
One end of the EGR passage 29 is open. moreover,
The other end of the EGR passage 29 opens to the exhaust passage 4 on the downstream side of the exhaust manifold.

An EGR valve 30 constituting an exhaust gas recirculation changing means is provided at the opening of the EGR passage 29 on the suction passage side, and this EGR valve 30 is driven to open and close by a diaphragm type pressure response device 31. ing. The pressure response device 31 has its EGR valve 30
An atmospheric passage 33 that guides atmospheric pressure Vat through an air filter 32 to a pressure chamber 31c partitioned by a diaphragm 31b connected to a rod 31a that drives the
and the vacuum pressure from the vacuum pump 25.
A vacuum passage 34 for guiding Vvac is connected to these passages 33 and 34.
An electromagnetic switching valve 35 and an electromagnetic on-off valve 3, respectively.
6 is interposed.

And the solenoid 35 of each electromagnetic valve 35, 36
When a control signal by duty control is supplied from the ECU 9 to a, 36a, each valve body 35b, 36
b is controlled by suction, thereby adjusting the negative pressure supplied to the pressure chamber 31c of the pressure response device 31, drawing the rod 31a appropriately, and controlling the opening degree of the EGR valve 30. Ru.

Note that the opening degree of the intake throttle valve 21 is determined by the rod 22a.
The opening of the EGR valve 30 is detected by a feedback signal sent to the ECU 9 from the intake throttle valve opening sensor 45 attached to the is detected by the feedback signal of

Then, the solenoid 37a of the electromagnetic valve 37
When a control signal is supplied from the ECU 9, the valve body 37
b is controlled by suction, whereby the intake pressure downstream of the intake throttle valve 21 is supplied to the pressure sensor 38 through the passage 40 interposed with the water trap 49', and the valve body of the solenoid valve 37 is supplied to the pressure sensor 38. 37b
At the time of protrusion, atmospheric pressure from the air filter 41 is supplied to the pressure sensor 38.

Further, the injection pump 17 is provided with a diaphragm type pressure responsive signal 46 as an idle up actuator constituting 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. A valve (hereinafter referred to as "electromagnetic valve" as necessary) 47 is connected, and this electromagnetic valve 47 connects the pressure chamber 46c and the vacuum pump 25 or air filter 48 as appropriate, and is normally connected to the air filter 48. and pressure chamber 46
It communicates with c.

Then, when a control signal by 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 designed to be suction controlled,
As a result, the pressure (negative pressure) supplied to the pressure chamber 46c of the pressure response device 46 is adjusted, and the rod 46
a is pulled in as appropriate to control the idle up state (high speed idle state).

Furthermore, the fuel injection timing control means 18 is capable of regenerating the DPO5 by combusting the particulate matter collected in the DPO5 by supplying high-temperature gas for particulate combustion containing oxygen gas from the diesel engine E to the DPO5.
It consists of a retard device that retards the fuel injection timing.

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 the oil pressure (fuel pressure) from the hydraulic pump, and controls the cam plate and the rollers. A hydraulic automatic timer (internal timer) is used to move the relative position of the motor.

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 FIGS. The timer piston 52 is installed in the pump housing 53 so as to be perpendicular to the pump drive shaft 54, and is slid within 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 the timer piston 52 passes through a slide piston 56 to a cylindrical roller ring 57.
It is now possible to convert it into a rotating motion.

Then, the position of the roller 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 push the timer piston 52 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. Due to this movement, the roller ring 57 is rotated in a direction opposite to the direction of rotation of the drive shaft, thereby advancing the injection timing.

Then, the oil supplied from the chamber 51 becomes high pressure in the plunger 63, and the delivery valve 64
The fuel is supplied to the fuel injection nozzle 65 through the fuel injection nozzle 65.

Further, hydraulic passages 67a and 67b are provided which can communicate the timer piston 52, the high pressure chamber 73, and the low pressure chamber 74, and the hydraulic passage 67a has a port (opening/closing part) 59 for switching between high advanced characteristics and middle advanced characteristics. A solenoid timer (opening/closing valve) ST equipped with a solenoid timer (opening/closing valve) 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 port 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.

A check valve 60 and an overflow orifice 61 are built into the main body of the solenoid timer ST, and the pressure oil supplied from the pump chamber 51 is supplied to the switching port 59 by opening the check valve 60.

When the control signal is not supplied to the solenoid of the solenoid timer ST (when off), the switching port 59 is opened and the middle advance (M) characteristic at partial time is established, and a control signal is supplied to the solenoid. (when on), the switching port 59 is closed and the high advance (H)
H) Becomes a characteristic.

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 FIGS. 4 and 5, the timer piston 52 receives pressure oil from the pump chamber 51 through an oil passage 52a into a high pressure chamber 73, and combines this oil pressure with two springs 55a and 55b on the low pressure chamber 74 side. The position of the timer piston 52 is adjusted by the spring force, and the roller ring 57 is thereby rotated.
Fuel injection timing is adjusted.

That is, there is a soft second
A timer spring 55 is installed, and the engine E
When the hydraulic pressure that has increased due to the start of
As shown in the figure, the fuel injection timing is 5° ATDC (After
Top Death Center).

Then, as the oil pressure is appropriately increased by the load sensing timer mechanism according to the rotational speed of the engine E, the first timer spring 55a is compressed, and the timer piston 52 moves to the left in FIG. 4.

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 Figure 8,
The characteristic of constant injection timing can be obtained when the engine speed is from N1 to N2 (>N1).

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

In this way, when the reed valve RV is turned off (open), the fuel pressure becomes low through the passage 67b, so the pressure inside the high pressure chamber 73 becomes low regardless of the engine speed value, and the timer piston 5
2 is pushed toward the right side in FIG. 4 by the first timer spring 55a and the second timer spring 55b, thereby bringing it into the low advance (full retard) position.

By the way, the increase ΔQ in the fuel injection amount per stroke of the fuel injection pump 17 to obtain the same output when retarding the fuel injection timing significantly reduces the thermal efficiency of the engine E by setting the retardation amount α. 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,
Here, all of the fuel corresponding to the fuel increase amount ΔQ is released as heat loss by setting the retardation amount α.
Although the increase or decrease in the amount of work itself is suppressed, the exhaust gas temperature rises due to such heat loss and incomplete combustion products
The combustion heat generated by oxidation by the catalyst on DPO5 increases the exhaust gas temperature.

Therefore, by delaying the injection timing (retarding) and increasing the fuel injection amount as described above, the exhaust gas temperature at the same output operating point increases, making it possible to burn the particulate on DPO5. , DPO5 can be played.

When the regeneration of the DPO 5 is completed, the ECU 9 outputs a signal to close the retard valve RV. At this time, the ECU 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.

In addition, the reference numeral 42 in FIG. 3 indicates a vehicle speed sensor, 43 indicates a clock, 44 indicates a temperature sensor that detects the engine temperature (cooling water temperature in this case) as an engine condition sensor, and 75 indicates a temperature sensor. indicates a warning light.

An exhaust deposit purge device for a filter device for an exhaust pressure detection sensor in a diesel engine as an embodiment of the present invention is configured as described above.
Control general flow of the entire system: first turn on the key switch (e.g. accessory position)
Start by making .

First, the reproduction 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, regeneration control is performed by controlling the injection timing and intake throttling amount, and whether or not regeneration has been completed is determined based on the pressure drop of DPO5.

Furthermore, if the regeneration flag is off, normal injection timing control and EGR control are performed. Then, it is detected whether it is time for regeneration based on the integrated value of the diesel particulate, the pressure loss of the DPO, etc.

Next, when the end of playback control is detected and after determining the playback timing, it is determined whether the key is off, and if the key is on, processing starts again from the playback flag on. 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, the valve body 79b is opened, and the valve body 78b is opened.
is closed, the pressure sensor 10 detects the pressure P ₂ on the downstream side of the DPO 5, and the valve body 78a is opened and the valve body 79b is closed, and the pressure sensor 10 detects the pressure P ₁ on the upstream side of the DPO 5. At the same time, the valve body 77b is opened, and the pressure sensor 1
0, atmospheric pressure (approximately equal to the pressure on the downstream side of the muffler 6) P ₀ is detected. (Refer to the symbol FD in Fig. 1) At this time, the electromagnetic switching valve 76 is in the OFF state, and the pulsation of the exhaust pressure is appropriately reduced by the filter devices 49a and 49b, so that variations in the measured values are reduced. decreases, allowing accurate exhaust pressure to be detected.

The filter devices 49a and 49b prevent water, soot, etc. from entering the sensor diaphragm of the pressure sensor 10, so that water accumulates in the sensor diaphragm, and in cold weather, this water freezes and forms the diaphragm. It can also solve the problem caused by the destruction of the

In addition, since moisture can be purged into the exhaust passage 4 by the purge mechanism PM, there are problems such as moisture accumulating in the slack part of the detection line and freezing, preventing exhaust pressure from being detected, and delays in exhaust pressure transmission due to soot. Problems such as this can also be resolved.

Furthermore, in the purge mechanism PM, a control signal is output from the ECU 9 based on the following conditions.

() Always other than exhaust pressure detection () Periodically (1) Immediately after engine startup (2) Every time exhaust pressure is detected (before and after, etc.) (3) At a certain time or a certain distance traveled () When engine operating conditions are met (1) Idle (2) During deceleration and solenoids 76a, 77a, 78a,
By opening (turning on) 79a at the same time,
The exhaust deposits in the filter devices 49a, 49b or the electromagnetic switching valve 77 and the filter 80 can be purged at the same time (see reference numeral FP in FIG. 1), or the solenoids 76a, 77a, 78a or the solenoid 7
By alternately opening (turning on) 6a, 77a, and 79a, exhaust deposits in the filter devices 49a and 49b, the electromagnetic switching valve 77, and the filter 80 are purged.

Then, calculate the main muffler pressure drop (P ₂ - P ₀ ) and DPO pressure drop (P ₁ - P ₂ ) from the above-mentioned pressures _{P 0} , P ₁ , and P 2 , and calculate the main muffler pressure drop and the main muffler pressure drop as shown in Figure 9.
When the DPO pressure drop moves from the area C ₂ to the area C ₃ at a boundary line corresponding to, for example, a loading amount of 70 g of particulate matter (Pct), the regeneration flag is turned on.

When the weight is 70g or less, the regeneration flag is turned on when other integrated values are greater than the set value.
Otherwise, the playback flag remains as it is.

In addition, instead of determining the loading amount of Pct using the above-mentioned map, it may be determined whether the DPO pressure drop _{P 1} is equal to or higher than the regeneration start setting pressure. Measured values may be used, or in order to eliminate variations in measured values, the average value of a large number of measured values or other statistical processing may be used.

The playback end determination process flow is a process flow that determines the playback end time and turns off the playback flag, and is almost the same as the playback start determination process flow.
Main muffler pressure loss (P ₂ −P ₀ ) and DPO pressure loss (P ₁ −
P ₂ ), and as shown in Figure 9, the main muffler pressure loss and DPO pressure loss have shifted from area C ₂ to area C ₁ , where the boundary line corresponds to, for example, a loading amount of 20 g of particulate matter (Pct). Sometimes the regeneration flag is turned off, otherwise the regeneration flag remains current.

As shown in Fig. 7, the injection timing control processing flow is based on the temperature of DPO5, that is, the DPO inlet temperature.
Tin, DPO internal temperature Tf or DPO outlet temperature _T0 is detected, and if this temperature T is 650℃ or higher, it is determined that the temperature is abnormally high, and the engine speed is determined by the abnormally high temperature map (Ne, θ). The injection timing is set based on the number Ne and the pump lever opening degree θ.

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°C or less, the map (Ne, θ) during normal driving will change when the regeneration flag is off.
Accordingly, the injection timing is set to be determined by the engine speed Ne and the pump lever opening degree θ.

If the regeneration flag is on, the injection timing is set according to the map (Ne, θ) at the time of regeneration, which is determined by the engine rotational speed Ne and the pump lever opening degree θ.

By switching the solenoid timer ST 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 if a sudden switching is performed, an acceleration/deceleration shock will occur. In order to reduce the shock during this switching, switching is performed over a sufficiently long time _t0 seconds (for example, 2 to 3 seconds) by duty control of the solenoid timer ST.

Solenoid timer with this duty control
ST switching is controlled according to regions (zones) divided by engine speed and lever opening. To achieve this, switching is performed quickly by on/off switching, and when transitioning from a retarded state to maximum output near the maximum output characteristic, switching is performed slowly by duty control to reduce shock.

Note that the switching time t ₀ by duty control may be a function of the engine rotation speed, or may have time hysteresis. Moreover, each of the above-mentioned numerical values is an illustration.

According to an exhaust deposit purge device for a filter device for an exhaust pressure detection sensor in a diesel engine as an embodiment of the present invention, the following effects or advantages can be obtained.

(1) Since a filter device was installed in the exhaust pressure detection piping that connects the exhaust pressure detection sensor and the exhaust passage,
The exhaust pressure detection sensor can always be kept clean, and malfunction of the regeneration device of the diesel particulate oxidizer can be prevented.

Further, since the filter device is purged using the intake air of the engine, exhaust deposits can be reliably removed to the intake system of the engine in a short time.

(2) Taking into consideration that the combustion speed increases as the exhaust temperature rises, the timing of the end of DPO combustion or the point at which combustion continues even if the operation of the regeneration assist mechanism is stopped is set earlier. Furthermore, it is possible to accurately detect and appropriately control the stoppage of the operation of the regeneration assisting mechanism based on the detected stop timing of the regeneration assisting mechanism.

(3) The wire mesh for the water trap makes it possible to reliably collect moisture, which allows 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 and moisture that could not be removed by the wire mesh.

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

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

Further, the exhaust pressure detection line may be heated by installing filter devices 49a and 49b including water traps in the engine room from the exhaust pressure detection sensor 10, thereby causing moisture in the exhaust pressure detection line to be heated. is evaporated and released into the atmosphere from the electromagnetic switching valve 77 when atmospheric pressure is detected.

In addition, although this example shows an example of application to a diesel engine with a supercharger, it is applicable to a diesel engine without a supercharger, that is, an NA
(Natural Aspiration) It can also be applied to diesel engines.

〔Effect of the invention〕

As described in detail above, according to the exhaust deposit purging device of the filter device for the exhaust pressure detection sensor in a diesel engine of the present invention, the exhaust passage and the exhaust pressure detection sensor are connected in the exhaust system of the diesel engine. a filter device for an exhaust pressure detection sensor installed in the exhaust pressure detection piping; an atmospheric control valve that controls communication of the piping on the sensor side of the filter device to the atmosphere; a suction pipe that communicates the pipe downstream of the intake throttle valve of the engine; and a suction control valve that controls whether the exhaust passage side of the filter device communicates with the exhaust passage or with the suction pipe. , switching between the atmosphere control valve and the suction control valve, and closing the intake throttle valve to send air to the engine via the atmosphere control valve to remove the deposits in the filter device by refluxing it downstream of the intake throttle valve; With a simple structure including a purge control section, the following effects and advantages can be obtained.

(1) Exhaust deposits such as moisture and soot in the exhaust pressure detection piping and exhaust pressure detection sensor filter device can be returned to the intake system and removed.

(2) According to paragraph 1 above, in cold regions, moisture collected in slack parts of exhaust pressure detection piping and filter devices installed in the piping may freeze.
It is possible to prevent the filter device and the exhaust pressure detection sensor from being destroyed, and furthermore, it is possible to prevent the pipes from being clogged with ice or the like.

(3) The purge effect can be further enhanced with a low load, thereby expanding the purgeable area.

(4) Exhaust deposits can be removed by suction into the intake system.
Purging with clean air can also be performed.

(5) With each of the above items, soot can be removed, so the detection accuracy of the exhaust pressure detection sensor is improved.

[Brief explanation of drawings]

1 to 10 show a regeneration device for a diesel particulate oxidizer equipped with an exhaust deposit purging device for a filter device for an exhaust pressure detection sensor in a diesel engine as an embodiment of the present invention. 2 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, and FIG. 5 6 is a hydraulic system diagram, FIGS. 6 a and b are sectional views and schematic diagrams showing the respective filter device bodies, and FIG.
Figure 8 is a graph to explain the required advance angle characteristics (required fuel injection timing characteristics), Figure 9 is a graph showing the amount of particulate accumulated in the DPO, main muffler pressure drop, and DPO pressure drop. FIG. 10 is a schematic diagram showing the operating state of the suction control valve. 1...Cylinder block, 2...Cylinder head, 3...Intake passage, 4...Exhaust passage, 5...Deep collection type diesel particulate oxidizer (DPO), 6...Muffler, 7...Rabbo charger , 8... Heat retention pipe, 9... Electronic control unit (ECU) that also serves as a regeneration auxiliary mechanism control means, an on-off valve control means, a calculation section, an 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 regeneration auxiliary mechanism control means, 1
9... Injection pump lever opening sensor (load sensor) as an engine condition sensor, 20... Engine rotation speed sensor as an engine condition sensor, 2
1...Intake throttle valve as intake negative pressure changing means, 2
2... Pressure response device, 22a... Rod, 22b
...Diaphragm, 22c...Pressure chamber, 23...
Air filter, 24... atmospheric passage, 25... vacuum pump, 26... vacuum passage, 27,
28... Solenoid valve, 27a, 28a... Solenoid, 27b, 28b... Valve body, 29... EGR passage, 30... Consists of exhaust gas recirculation amount changing means
EGR valve, 31...pressure response device, 31a...rod, 31b...diaphragm, 31c...pressure chamber, 32...air filter, 33...atmospheric passage,
34... Vacuum passage, 35-37... Solenoid valve, 35a, 36a, 37a... Solenoid, 3
5b, 36b, 37b... Valve body, 38... Pressure sensor, 39... Position sensor, 40... Passage, 41... Air filter, 42... Vehicle speed sensor, 43... Clock, 44... Engine condition sensor 45... Intake throttle valve opening sensor, 46... Idle up actuator constituting the idle up mechanism, 46a... Rod, 46b... Diaphragm, 46c... Pressure chamber, 47... Electromagnetic Valve, 47a...Solenoid, 4
7b... Valve body, 48... Air filter, 49...
Casing, 49'...Water trap, 4
9a, 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, 52a ...Oil passage, 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, 65 ... Fuel injection nozzle, 66 ... Orifice, 67a, 67b
... Hydraulic passage, 68 ... Retainer, 69 ... Rod, 69a ... Snap spring, 70 ... Shim,
71... Stopper, 72... O-ring, 73...
High pressure chamber, 74...Low pressure chamber, 75...Warning lamp, 76...Solenoid switching valve as suction control valve, 76a...Solenoid, 77-79...Solenoid switching valve, 77a-79a...Solenoid , 77
b~79b... Valve body, 80... Air filter, 8
1... Main chamber, 82... Piston, 83... Damping volume for reducing exhaust pulsation, 84... Wire mesh, 85... First stage filter, 85a...
...PVF filter part, 85b... AC-26 filter part, 86... Second stage filter, 86a...
PVF filter part, 86b... AC-26 filter part, 87... Spacer, 87a... Hole, 88,
88'...FRM O-ring, 89...SUS plate, 90, 91...Pressure sensor side volume,
92, 93...Housing, 94a, 94b, 9
4'a, 94'b...Piping for exhaust pressure detection, 95...Piping for suction, 96...Intake valve, 97...Exhaust valve, 9
8... Air filter, E... Diesel engine, PM... Purge mechanism, RV... Retard valve as an on-off valve, ST... Solenoid timer as an on-off valve.

Claims (1)

[Claims] 1 In the exhaust system of a diesel engine, a filter device for an exhaust pressure detection sensor installed in an exhaust pressure detection piping connecting an exhaust passage and an exhaust pressure detection sensor, and the piping on the sensor side from the filter device. an atmospheric control valve that communicates the exhaust passage side of the filter device with the atmosphere; a suction pipe that connects the piping on the exhaust passage side of the filter device to the downstream side of the intake throttle valve of the engine; and a suction piping that connects the exhaust passage side of the filter device with the exhaust passageway. and a suction control valve that switches between communicating with the atmosphere control valve and the suction control valve, and closing the intake throttle valve and controlling the air flow through the atmosphere control valve. An exhaust deposit purge device for a filter device for an exhaust pressure detection sensor in a diesel engine, comprising a purge control section that sends air to the engine and causes the deposits in the filter device to be returned and removed downstream of the intake throttle valve. .