JPS60206923A - Diesel particulates catching member protector - Google Patents

Abstract

PURPOSE:To protect the catching member from overheat by increasing the idle engine rotation when the temperature of the particulate catching member is higher than predetermined level thereby increasing the exhaust flow and increasing carrying amount of heat. CONSTITUTION:In a system where the particulates in the exhaust gas from an engine E are caught by an oxidizer 5 arranged in an exhaust path 4, a pressure responsive diaphragm 46 is provided as an idle-up actuator to a fuel injection pump 17. Said diaphragm 46 is functioned by the atmospheric pressure fed through a three-way changeover valve 47 and an air filter 48 into the pressure chamber 46c or the vacuum pressure fed from a vacuum pump 25. Then a solenoid 47a in the three-way changeover valve 47 is controlled through an electronic controller such that said diaphragm 46 is brought into the idle-up condition upon exceeding of the temperature of the oxidizer 5 to be detected through a temperature sensor 15 over predetermined level.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diesel engine equipped with a diesel particulate collection member, and more particularly to a protection device for the diesel particulate collection member.

Diesel engine exhaust contains particulates, which are flammable, fine carbonized compounds, and are the main cause of black smoke in the exhaust. These particulates spontaneously ignite and burn when the vehicle is running at high speed and under high load when the exhaust temperature reaches, for example, 500°C or higher (hereinafter referred to as "
It is said to be self-combusting. ), but 501) 'C is not reached during steady driving or idling (accounts for more than 90% of vehicle operation)
, it is released directly into the atmosphere.

However, since particulates may be harmful to the human body, research has been actively conducted in recent years to install a diesel particulate collection member in the exhaust passage of a vehicle diesel engine.

By the way, this diesel particulate collection department month 1
When soil is used, particulates tend to collect and accumulate and block the exhaust passage, so research into devices for re-combusting particulates is underway to regenerate diesel particulate collection members.

Such regeneration devices include, for example, the use of various burners, the retardation of injection pumps, and the discharge of exhaust gas containing a large amount of carbon monoxide compounds, which are activated by oxidation catalysts to make them highly combustible. It has been proposed to use a device that does this.

However, with these conventional means, especially when a particulate collection member (diesel particulate oxidizer: DPO) with a catalyst containing platinum, palladium, or rhodium is used, the DPO temperature is sufficiently high. When deceleration is performed at 411
If the air temperature rises too much, in the worst case, the diesel particulate collection member may melt or the catalyst equipped with the diesel particulate collection member may deteriorate.

The present invention aims to solve these problems by preventing a decrease in the exhaust flow rate by increasing the idle engine speed when the temperature of the diesel particulate collection member is above a predetermined value. It is an object of the present invention to provide a diesel particulate collection member protection device that suppresses a temperature rise during regeneration of the diesel particulate collection member.

Therefore, the diesel particulate collection member protection device of the present invention is a diesel particulate collection member disposed in the exhaust passage of the diesel engine to collect particulates from the combustion chamber of the diesel engine. , a regeneration mechanism capable of regenerating the diesel particulate collection member by burning particulates collected in the diesel particulate collection member, a regeneration control means for controlling the operation of the regeneration mechanism, and the diesel engine. temperature detection means for detecting the temperature of the diesel particulate collection member, and a temperature detection means for detecting the temperature of the diesel particulate collection member; Particulate combustion suppressing means is provided for outputting a control signal to the idle-up actuator to increase the idle engine speed of the diesel engine when the temperature of the collecting member is above a predetermined value. It is characterized by

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
The figures show a diesel particulate collection member protection device as an embodiment of the present invention. Fig. 1 is its overall configuration diagram, Fig. 2 is its block diagram, and Fig. 3 is its idle-up actuator. Diagram showing the arrangement state, No. 4,
Figures 5 and 6 are graphs to explain their effects, respectively.
The figure is a flowchart showing the control procedure, and FIG. 7 shows the subsequent operation of the hydraulic system for the fuel injection timing control means.

As shown in FIGS. 1 and 2, this diesel engine E has a cylinder block 1. The cylinder head 21 has a main chamber formed by a piston (not shown) and a sub-chamber (not shown) formed in the cylinder head 2 and communicating with the main chamber.

Further, an intake passage 3 is connected to the main chamber of this diesel engine E via an intake valve (not shown), and an exhaust passage 4 (41) is connected to the main chamber via an exhaust valve (not shown). A diesel particulate collection unit 5 is interposed to capture particulates in the exhaust gas.

Note that particulates here refer to combustible fine particles mainly composed of carbon and hydrocarbons, with an average diameter of about 0.3 μm and a temperature of about 500°C or higher (350°C or higher in the presence of an oxidation catalyst). self-ignites.

The diesel particulate collection member 5 is a 7-ohm deep trap type heat-resistant ceramic with a catalyst containing platinum, palladium, or rhodium inside (this is a flat plate with an oval, oblong, or oval cross-sectional shape). A rectangular shape, etc.) is used.1)
Hereinafter, this diesel particulate collecting member will be abbreviated as <I) PO (diesel particulate oxidizer).

DPO5 communicates with the atmosphere via a muffler 6,
Exhaust gas from the engine E is received via the turbine of the turbocharger 7 and the heat insulating pipe 8.

A pressure sensor 10 that detects the exhaust pressure of the inlet/outlet side exhaust passage 1184 of the DPO5 and outputs a detection signal of the ECtJ91 (described later) operates an electromagnetic three-way switching valve (hereinafter referred to as "electromagnetic valve" as necessary) 11.12. Attached via.

Each solenoid valve 1.1.12 receives a control signal from an electronic control unit (ECU) 9 configured by a computer or the like through its respective solenoids 11a and 12a, and its valve body]
1b and 12b, atmospheric pressure P, (this level) 0. is the downstream side of 77ra 6) which is also the main force),
D when the valve body 11b is in the suction state and the valve body 12b is in the protruding state.
The downstream (output 1) exhaust pressure P2 of PO5 is controlled by the valve body 11b,
In the suction state of 12b, the upstream (inlet) exhaust pressure P of DPO
1 is detected.

In addition, an exhaust passage 4 adjacent to the inlet (upstream) of the DPO 5
, a temperature sensor (
A thermocouple 14 is provided, and a temperature sensor (thermocouple) 16 is further provided in the exhaust passage 4 close to the outlet (downstream) of the DPO 5 to detect the temperature To of the DPO outlet 71.

In addition, a temperature sensor (
A thermocouple) 15 is provided. That is, these temperature sensors 14 to 16 constitute a temperature detection means for detecting the DPO temperature.

Detection signals from each of these temperature sensors 14 to 16 are input to the ECU 9.

By the way, the fuel injection pump 17 used in this diesel engine E receives a control signal from the ECU 9 and can adjust the fuel injection timing by a fuel injection timing control means 18 that constitutes a regeneration mechanism. This injection pump 17 has
The injection pump lever opening degree sensor 19 is marked (=1), and the pump lever opening degree information is output to the ECLI 9.

Note that the reference numeral 20 indicates a rotation speed sensor that detects the rotation speed of the engine 1.

In the intake passage 3 formed by the intake manifold fixed to the engine E and the intake pipe following this, an air cleaner and a humplen sheath intake throttle valve 21 of the turbocharger 7 are arranged in order from the upstream side (atmospheric side). There is.

The intake throttle valve 21 is driven to open and close by a diaphragm pressure response device 22. The pressure-responsive device 22 includes a diaphragm 22b connected to a rod 22a that drives the intake throttle valve 21, and a pressure chamber 22c partitioned by the diaphragm 22b is supplied with atmospheric pressure Vat through an air filter 23. Leading atmosphere passage 2
4 and the vacuum pressure from the vacuum pump 25\/
It is connected to a vacuum passage 26 that guides the vac,
These passages 24.2[3 are provided with an electromagnetic on-off valve (hereinafter referred to as [electromagnetic valve] as needed) 27 and an electromagnetic on-off valve (hereinafter referred to as [electromagnetic valve] as necessary) 28, respectively. equipped.

And the solenoids 27a, 28 of each electromagnetic valve 27, 28
When a control signal for duty control is supplied from the ECU 9 to a, each valve element 27+1, 281) is suction-controlled, thereby reducing the pressure supplied to the pressure chamber 22c of the pressure-responsive device 22. (Negative pressure) is adjusted, the rod V22a is appropriately retracted, and the throttle amount of the intake throttle valve 21 is controlled.

Further, one end of a passage 29 for bleed air recirculation (hereinafter referred to as EGR) is opened in the intake passage 3 on the downstream side of the intake throttle valve 21 .

Note that the other end of the EGR passage 29 opens to a portion of the exhaust passage 4 on the upstream side of the portion where the turbine of the turbocharger 7 is disposed.

Furthermore, an exhaust gas recirculation amount control valve (hereinafter referred to as "EGR valve") 3 ( ) is provided at the intake passage side opening of the EGR passage 29 , and this EGR valve 30 is opened and closed by a diaphragm type pressure response device 31 . It is designed to be driven.

This pressure response device 31 is equipped with a Guia 7 ram 31b connected to a rod 31a that drives the EGR valve 30. Atmospheric pressure\'at
An atmospheric passage 33 that guides the vacuum pressure V vac from the vacuum pump 25 and a vacuum passage 34 that guides the vacuum pressure V vac from the vacuum pump 25 are connected to each other. (referred to as "solenoid valve")3
5 and an electromagnetic on-off valve (hereinafter referred to as "electromagnetic valve" as necessary) 36 are interposed.

And the solenoids 35a, 3 of each solenoid valve 35,36
When a control signal by duty control is supplied from the CU 9 to 6a, each valve element 35b, 36b is suction-controlled, and thereby the pressure-responsive device 31
The pressure (negative pressure) supplied to the pressure chamber 3]c is adjusted,
The rod 31a is appropriately retracted to limit the opening degree of the EGR valve 3().

Note that the opening degree of the intake throttle valve 21 is determined by controlling the opening degree of the intake throttle valve 21 through an electromagnetic three-way switching valve (hereinafter referred to as "electromagnetic valve" as necessary) 37 in the intake passage 3 on the downstream side of the installation position of the intake throttle valve 21. The opening degree of the EGR valve 30 is detected by a feedback signal from the attached pressure sensor 38 to the ECtJ9, and the opening degree of the EGR valve 30 is determined by a feed signal to the ECU 9 from a position sensor 39 that detects the movement of the a-rad 31a of the pressure response device 31.

detected by the signal.

Then, ECtJ 9 is connected to the solenoid 37a of the solenoid valve 37.
When a control signal is supplied from the solenoid valve, each valve body 37b is suction-controlled, whereby the intake pressure downstream of the intake throttle valve 21 is supplied to the pressure sensor 38 via the passage 40, and the solenoid valve When the valve body 37b of No. 37 protrudes, atmospheric pressure from the air filter 41 is supplied to the pressure sensor 38.

Further, a position sensor 45 is also provided to detect the movement of the rod 22a of the pressure response device 22, and the opening degree of the intake throttle valve 21 is determined from this position sensor 45 by ECtJ9.
feedback has been provided.

Furthermore, by supplying high-temperature gas for particulate combustion containing oxygen gas to the DPO5 from the diesel engine E, a regeneration mechanism (or a regeneration auxiliary mechanism) is installed that can promote the regeneration of the DPO5 by combusting the particulates collected in the DPO5. ) constitutes a fuel injection timing control means 18
is constituted by a fuel injection timing adjustment device that retards the fuel injection timing of the injection pump 17. When the injection pump 17 is configured as a distribution type injection pump, the fuel injection timing control means 18 includes:
A hydraulic automatic timer (internal timer) is used in which the timer piston is driven by hydraulic pressure from a hydraulic pump to move the relative position of the cam plate and roller.

Further, as shown in FIG. 7, the fuel injection timing control means 18 includes a solenoid timer solenoid valve 1811 and a retard valve 18c for changing the state of the oil pressure p applied to the timer piston 18a.
When trying to promote regeneration of the D P O5, the solenoid timer solenoid valve 18b is turned on to close the oil passage 50, and the retard valve 18c is turned off to open the oil passage 51, thereby supplying pressure oil 1 to the timer piston 18a.
] is not supplied, a retarded characteristic (low advance characteristic or full retard characteristic) is realized regardless of the engine speed, as shown by the reference numerals in FIG.

In other cases, the characteristics indicated by symbol H in FIG. 5 can be obtained by turning on and re-off the solenoid timer solenoid valve 18b with the retard valve 18c on, that is, with the oil passage 51 closed. (high-advanced characteristics) and characteristics indicated by symbol M (middle-advanced characteristics) can be obtained.

Here, numerals 52 to 54 in FIG. 7 are orifices, and 55
is a check valve, 56 is a regulating valve,
57 is a feed pump, 58 is a pump chamber, 5! J indicates a plunger, 60 a delivery valve, and 61 a nozzle.

Note that a conventionally known timer control valve may be used as means for changing the state of the oil pressure 1) acting on the timer piston 18a.

Further, the fuel injection amount is increased by the driver operating the accelerator pedal to correct the decrease in output due to the delay in the injection timing.

Furthermore, as shown in FIGS. 1 and 3, the injection pump 17 is provided with a diaphragm pressure response device 46 as an idle-up actuator.

This pressure response device 46 is a rod 4 that drives an arm (idle up control unit) 46d for increasing the opening of the injection pump lever 17a, which adjusts the minimum injection position of the injection pump lever 17a.
6a, and a pressure chamber 46c partitioned by this diaphragm 461].
, a solenoid three-way switching valve (hereinafter referred to as a "solenoid valve" as required)
) 47 and the air filter 48 to atmospheric pressure\
'at' or the vacuum pressure V vac from the vacuum pump 25 is introduced.

In other words, when a control signal by duty control is supplied from the EC1J9 to the idle-up actuator control solenoid 47a of the solenoid valve 47, the valve element 47b is suction-controlled. The pressure (negative pressure) supplied to the pressure chamber 46c of 46 is adjusted, the rod 46a is retracted as appropriate, and the idle-up state (high-speed idle state) is controlled.

By the way, the increase AQ in the fuel injection amount per stroke of the injection pump 17 is determined by the setting of the retardation amount α, which significantly reduces the thermal efficiency of the engine E.
The effective work 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 retard amount a, the amount of heat equivalent to the amount of fuel increase AQ is completely reduced to heat loss. However, the increase in exhaust gas temperature due to such heat loss and the combustion heat generated by the oxidation of incomplete combustion products by the catalyst on DPO5 cause the exhaust gas temperature to rise above fl. .

Therefore, by delaying the injection timing (retarding) and simultaneously increasing the fuel injection amount by the driver's accelerator pedal operation, the exhaust gas temperature becomes high and the D
Combustion of particulates on PO5 can be promoted, and DPO5 can be removed by regeneration.

As shown in Fig. 2, the pressure sensor 1 () is connected to the ECU 9.
.

(Exhaust pressure and intake pressure from 8, temperature sensors 14 to 1
I) PO artificial exhaust temperature, DPO internal temperature and Dl) 0 output L1 exhaust temperature (these temperatures are collectively referred to as rDPo temperature) from 6, pump lever opening degree of the injection pump lever opening degree sensor 19, Ennon rotation speed sensor 2
Detection signals of the engine rotational speed from zero and the amount of secondary air from the position sensor 39 are input, as well as a vehicle speed sensor 42 that detects the vehicle speed. Each signal, including a water temperature sensor 449 that detects the engine cooling water temperature and a clock 43 that keeps track of the time, is manually generated.Receiving these signals, the ECU 9 performs the processes described below, and sends control signals suitable for each process to the exhaust gas. Introduction solenoid 12a, exhaust pressure sensor solenoid)
"lea, fuel injection timing control means 18. Intake throttle valve opening control solenoid 27a, intake throttle valve closing control solenoid 28a.

EGR valve closing control solenoid 35a, EGR valve opening control solenoid 36a, intake pressure sensor solenoid 3
7a.

In addition to outputting to the idle-up actuator solenoid 47a, power is also output to an awning lamp 62 that is turned on when a predetermined amount or more of particulates accumulate on the DPO 5.

ECU9 is the CPU, input/output interface, or R
The regeneration control means M1 is configured to include a memory (including a map) such as AM or ROM, and controls the operation of the fuel injection timing control means 18; the EGR amount control means M2 controls the operation of the EGR valve 30; An intake throttle amount control means M3 that controls the operation of the intake throttle valve 21 and a solenoid 47a for the idle-up actuator 47 so that the engine speed does not fall below, for example, 1500 rpm when the DPO temperature is higher than, for example, 600°C. particulate combustion suppressing means M4 that outputs a control signal to
It has the following functions.

With the above configuration, 1), muffler pressure loss (p2-p.) and D
I) Determine whether or not to promote the regeneration of DPO5 based on information on O pressure drop (P, -P2), integrated value information on engine speed, or integrated information on the product of engine speed and lever opening degree. Later, if the particulate loading amount is larger than the predetermined value based on the above information, 1)
When it is determined that it is not necessary to promote PO regeneration, the injection timing is fully retarded by the regeneration control means M1.

As a result, DPO population temperature Tin, DPO internal temperature T
"And the DPO outlet temperature T." increases as shown in FIG.

The intake throttle valve 20 is operated to throttle the intake air as appropriate.
) By reducing the amount of intake air by a predetermined amount, 41
1 Promote the upper row of temperature. Note that the target intake throttle opening or target intake pressure is stored in a map in accordance with the engine rotational speed and the pump lever opening.

In addition, when the fuel injection timing control means 18 as a regeneration auxiliary mechanism is operating as described in item 1, in order to minimize the driving feeling during regeneration, as a general rule 1-,
GR is cut.

As the DPO temperature rises in this manner, the idle-up control, which is a feature of this device, performs its function. That is, as shown in FIG. 6, in step A1, D
PO temperature detection is also done in step A2 when the DPO temperature is 6.
It is determined whether it is higher than 00''C.

If the DPO temperature is lower than 600°C, the process returns after stopping the process shown in Fig. 6 to continue promoting regeneration, but if the DPO temperature exceeds 600°C,
In step A3, the idle up actuator 46
is activated to increase the fully closed stopper position of the injection pump lever 17a by a certain angle, thereby increasing the idle engine speed and preventing the engine speed from becoming less than 1500 rpm, for example. This makes it possible to increase the exhaust flow rate, thereby increasing the amount of heat removed, and as a result, excessive temperature rise of the DPO 5 is suppressed.

Thereafter, in step A4, the DPO temperature is detected, and in step A5, the DPO temperature is again determined in the hope that the excessive temperature rise of the DPO5 has been suppressed.

In this step A5, the DPO temperature is still 550°C.
If it is higher than , idle 7 actuator 4
Monitor the temperature state of DP05 while keeping DP05 in operation.

If it is determined in step A5 that the DPO temperature is 550°C or less as a result of suppressing excessive temperature rise due to engine idle up, it is assumed that the risk of melting of DPO5 has disappeared, and in step A6, idle up is canceled. It is done.

Note that l) If the PO temperature is abnormally high and the engine is decelerating, the intake throttle valve 20 is driven to the closed side to reduce the excess air ratio, thereby preventing excessive temperature rise of the DPO5. Although we are trying to suppress the
The intake throttle valve 20 is fully opened.

Yoda, l) During P 05 playback or normal driving,
DI) When the O temperature becomes abnormally high (e.g. 600″
C), the EGR valve 30 is opened and an appropriate amount of E (iR) is applied.

Note that the reference numerals 49 and 49' in FIG. 1 indicate an over-water F-lap (steam/water separator).

Moreover, as the clock 43, a built-in clock in the ECU 9 may be used.

Furthermore, this device can also be applied to a protection device for a diesel particulate filter (usually referred to as a diesel particulate filter or [)PF) when forcedly regenerating a diesel particulate collection member that does not have a catalyst.

As detailed above, according to the diesel particulate collection member protection device of the present invention, the device is arranged in the exhaust passage of a diesel engine to collect particulates from the combustion chamber of the diesel engine. A diesel particulate collection member, a regeneration mechanism capable of regenerating the diesel particulate collection member by burning particulates collected in the diesel particulate collection member, and a regeneration mechanism that controls the operation of the regeneration mechanism. comprising a control means and an idle-up actuator capable of controlling the idle state of the diesel engine,
Temperature detection means for detecting the temperature of the diesel particulate collection member is provided, and when the temperature of the diesel particulate collection member is equal to or higher than a predetermined value upon receiving a signal from the temperature detection means, the diesel particulate collection member detects the temperature of the diesel particulate collection member. The diesel particulate collection member described in - is a By increasing the idle engine speed under conditions that are likely to cause heat loss, the exhaust flow rate can be increased and the amount of heat carried away can be increased.
For example, even during sudden deceleration from high speed and high load, it is possible to suppress the temperature rise during regeneration of the diesel particulate collection part, which prevents the diesel particulate collection member from melting or the catalyst from deteriorating. As a result, there is an advantage that the diesel particulate collection member is sufficiently protected.

[Brief explanation of the drawing]

The figures show a diesel particulate collection member protection device as an embodiment of the present invention. Fig. 1 is its overall configuration diagram, Fig. 2 is its block diagram, and Fig. 3 is its idle-up actuator. Diagram showing the arrangement state, No. 4,
Figures 5 and 6 are graphs to explain their effects, respectively.
The figure is a 70-chart showing the control procedure, and FIG. 7 is a hydraulic system diagram for the fuel injection timing control means. 1. Cylinder block, 2. Cylinder head, 3.
・Intake passage, 4. Exhaust passage, 5. Diesel particulate collection member (DPO), 6. Muffler, 7.
・Turbocharger, 8..Heating tube, 9..Electronic control unit (ECU), 10..Pressure sensor, 11.12..Solenoid three-way switching valve, lla, 12a..Solenoid, 13.
...F filter, 14-16...Temperature sensor constituting the temperature detection means, 17...Injection pump, 17a...Injection pump lever, 18...Fuel injection timing control means constituting the regeneration mechanism, 18a...Timer Piston, 18)]...
Solenoid valve for solenoid timer, 18c, retard valve, 19... Injection pump lever opening sensor, 2
0...Engine speed sensor, 21...Intake throttle valve, 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..EGR valve, 31..Pressure response device, 31a..Rod, 31b..Diaphragm, 3
1c...Pressure chamber, 32, φ air filter, (3...Atmospheric passage, 34...Vacuum passage, 35~:(7...Solenoid valve, 35a, 36a+37a...Solenoid, 35
b, 3 G b, 3711... Valve body, 38... Pressure sensor, 39φ, Position sensor, 40φ, Passage, 41-
- Air filter, 42... Vehicle speed sensor, 43... Clock, 44... Water temperature sensor, 45... Potentiometer,
46...) 1 force response device, 46a... rod, 4Gb...
・Diaphragm, 4Gc...Pressure chamber, 46d...Arm for increasing injection pump lever opening, 47...Solenoid valve, 47a
... Solenoid, 47b ... Valve body, 48 ... Air filter, 49.49' ... Two-way trap, 50.51
・・Oil passage, 52-54・・Orifice, 55・・Check valve, 56・・Regulating valve, 57・
・Feed pump, 58...Pump chamber, 59...Plant holder, 60...Delivery valve, 61...Nozzle, 62
・・Warning lamp, E・・Diesel engine,
Ml...Regeneration control means, M2...EGR amount control means, M
3. Intake throttle amount control means, M4. Particulate combustion suppression means. Agent Patent Attorney Yoshihiko Iinuma Figure 2 Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] In a diesel engine, there is a diesel particulate collection member disposed in the exhaust passage to collect particulates from the combustion chamber of the diesel engine, and a diesel particulate collection member that collects particulates collected in the diesel particulate collection member. The above-mentioned diesel engine is equipped with a regeneration mechanism that can regenerate the diesel particulate collection member by combustion, a regeneration control means that controls the operation of the regeneration mechanism, and an idle-up actuator that can control the idle state of the diesel engine. Temperature detection means for detecting the temperature of the diesel particulate collection member is provided, and when the temperature of the diesel particulate collection member is equal to or higher than a predetermined value upon receiving a signal from the temperature detection means, the diesel engine 1. A diesel particulate collection member protection device, comprising particulate combustion suppressing means for outputting a control signal to the idle-up actuator to increase the idle engine speed.