JP3294346B2 - Exhaust gas purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for collecting and regenerating particulate components (particulates) contained in exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art Japanese Utility Model Publication No. 2-18275 discloses
A temperature sensor for detecting the temperature of the filter is provided for regenerating the particulate matter collected by the filter disposed in the exhaust passage of the diesel engine, and the temperature sensor detects a temperature signal corresponding to a predetermined threshold temperature or higher. If the output is continued for more than the time, it is determined that the filter regeneration is completed.

[0003]

However, in the above-described conventional filter regeneration method, the completion of regeneration is determined by the temperature signal output from the temperature sensor. It is not possible to properly control the power supply to the heating means). For this reason, if the power supply is excessive, the filter may be damaged or cracked, and if the power supply is insufficient, unburned portions may occur due to poor regeneration. If unburned residues occur, the amount of particulates collected during the next regeneration will be excessive, and the filter may be damaged or cracked.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an exhaust gas capable of eliminating problems such as erosion, cracks, or unburned filter despite the malfunction of temperature detecting means for detecting the filter temperature. Providing a gas purification device is an issue to be solved.

[0005]

An exhaust gas purifying apparatus according to the present invention detects a filter disposed in an exhaust path of a diesel engine and a temperature of the filter, as shown in FIG. Temperature detecting means, an electric heating means for regenerating the filter by burning the particulates collected by the filter by heating the filter, and an electric heating means for regenerating the filter based on a temperature signal outputted from the temperature detecting means. In an exhaust gas purifying apparatus, comprising: a control unit that causes the electric heating unit to perform the regeneration by energization control; the control unit includes a temperature signal abnormality determination unit configured to determine whether the input temperature signal is abnormal; When it is determined that the signal is abnormal, instead of the energization control based on the temperature signal, the energization power to the electric heating means is changed from the ignition power.
Control that lowers the combustion maintenance power
And a power-on time control means for causing the electric heating means to perform the regeneration by controlling the power supply to the electric heating means using the parameter as a parameter . In a preferred aspect of the present invention, the air conditioner further comprises blowing means for introducing air for burning the particulates into the filter, wherein the energization time control means determines whether the temperature signal is normal. The air blower controls the blower to perform the regeneration by the blower control of the blower based on the temperature signal. It is characterized by causing the means to perform the reproduction. In another preferred aspect of the present invention, the temperature signal abnormality determining unit determines that the temperature signal is abnormal when a temperature rise rate of the filter after starting the energization to the electric heating unit is equal to or more than a predetermined value. Is characterized.

[0006]

The filter is heated by the electric heating means to burn the particulates and regenerate the filter. At this time, the temperature detecting means detects the temperature of the filter (or the temperature corresponding thereto) and outputs a temperature signal to the control means. The control means controls the power supplied to the electric heating means based on the temperature signal. Temperature signal abnormality determination means determines an abnormality of the temperature signal, the energization time control means energized conductive during temperature signal abnormality
Power reduced from ignition power to lower combustion maintenance power
Performing a defective despite filter regeneration temperature detecting means by switching forced us to control reproduction by energization time to the heating means at a predetermined energization pattern in which a parameter to. For example, when a temperature abnormality is detected, the above timer control is performed to control the air blowing with a predetermined air blowing pattern.

In this way, even if the temperature detecting means malfunctions or breaks during the regeneration operation, it is possible to avoid problems such as erosion of the filter, cracks, or unregeneration of the particulates. An excellent effect of improving the reliability can be achieved.

[0008]

【Example】

(Embodiment 1) One embodiment of the exhaust gas purifying apparatus of the present invention is shown in FIG. This exhaust gas purifying apparatus has a filter housing case 1 sealed at both ends, and a heater (electric heating means in the present invention) is provided in the filter housing case 1 from the upstream side to the downstream side.
11, a temperature sensor (temperature detecting means in the present invention) 6 and a filter 2 are arranged in this order. A tail pipe 4 is provided so as to penetrate the side wall of the downstream end of the filter housing case 1, and the tail pipe 4 has a built-in rectifying plate 14 for deflecting the wind direction in the filter housing case 1. Similarly, an exhaust pipe 3 of a diesel engine (not shown) is provided so as to penetrate a side wall of an upstream end portion of the filter housing case 1, and the exhaust pipe 3 in the filter housing case 1 is rectified for wind direction deflection. The plate 14 is built in.

An outlet of an air supply pipe 10 is provided through an upstream end wall of the filter housing case 1, and the air supply pipe 10 is connected to an outlet of a blower 13 through an electromagnetic valve 12. Further, the exhaust pipe 3 is provided with a pressure sensor 7 for detecting an exhaust pressure and an electromagnetically driven relief valve 16 for discharging exhaust gas from the exhaust pipe to the outside. On the other hand, the heater 11, the blower 13, the valve 12, and the relief valve 16 are driven and controlled by a controller (control means in the present invention) 8, and have an air flow sensor 5, a pressure sensor 7, and a built-in engine (not shown). The signal of the temperature sensor 6 is output to the controller 8. Further, the controller 8 receives a signal from a reproduction switch for instructing a reproduction start, and turns on an abnormality alarm lamp 9 when an abnormality occurs.

Hereinafter, the operation of this apparatus will be described. (Particle collection operation) Exhaust gas discharged from the diesel engine is introduced into the case 1 through the exhaust pipe 3, and particulates in the exhaust gas are collected by the filter 2, and the purified exhaust gas is collected. It is discharged from the tail tube 4 to the outside.

The filter 2 is a honeycomb ceramic filter (manufactured by Nippon Insulator KK, diameter: 5.66 inches × length: 6 inches), which is fired in a cylindrical shape using cordierite as a material. The filter 2 has a number of vents penetrating both end faces, one of the adjacent vents is plugged at the upstream end and the other is plugged at the downstream end. Exhaust gas passes through the porous partition between adjacent vents, and only particulates are trapped in the vents. Both end faces of the filter 2 face both end faces of the case 1 at a predetermined distance.

The heater 3 is made of an electrothermal resistor made of a nichrome wire, and is arranged close to the end face of the filter 2 which is on the upstream side during regeneration. (Filter regeneration operation) Next, the regeneration operation of the filter 2 will be described with reference to the flowcharts of FIGS. In this device, the filter regeneration operation is performed during the engine stop period.

First, at 100, based on the exhaust pressure detected by the pressure sensor 7, the intake air flow rate detected by the air flow sensor 5, and the exhaust gas temperature detected by the temperature sensor 6, a memory (FIG. (Not shown), the amount of particulates P collected by the filter 2 is searched. The pressure loss of the filter 2 is a function value with the exhaust pressure, the intake air flow rate and the exhaust gas temperature as variables, and the particulate collection amount is a function value with the pressure loss as a variable. Of course, various methods for estimating the amount of collected particulates are known, and any of them may be selected.

Next, it is checked whether or not the collected amount of collected particulates P exceeds a predetermined threshold value Pt (1).
02), if exceeded, proceed to 104 to enter the reproducing operation; otherwise, return to 100. Step 10
In step 4, power necessary for ignition (hereinafter, ignition power) is supplied to the heater 11 and a built-in timer is started (106).

Next, after a lapse of a predetermined time (for example, three minutes) from the start of energization of the heater, a temperature signal output from the temperature sensor is read out (110), and it is determined whether the temperature signal is lower than a predetermined temperature t0 at which the temperature rise is close to zero. Is checked (112), and if it is below, the lamp 9 is turned on (114), and a timer control subroutine described later is executed (116), and step 136 is executed.
Proceed to.

On the other hand, if the temperature signal exceeds the predetermined temperature t0, the temperature signal becomes T1 (here, 250 degrees Celsius).
Is checked (118), and if so, the valve 12 is opened, the blower 13 is driven to introduce the external air into the filter 2 and proceeds to 122 (121), Past 1 if not exceeded
It is checked whether or not the heating rate per minute exceeds a = 1 degree Celsius / minute (120).
If it falls below, it is determined that there is an abnormality and the process returns to 114.

At 122, it is checked whether or not the temperature signal has exceeded T2 (here, 500 degrees Celsius) (that is, whether or not the ignition period has passed). Temperature rate a = 1 degree Celsius /
It is determined whether or not the time exceeds the minute (124). If the time exceeds the minute, the operation is returned to 121 as normal operation, and if the time is shorter, the operation is returned to 114 as abnormal.

At 126, the above T1 (here, 25 degrees Celsius)
It is checked whether the required time t (T1 to T2) from 0 degree) to T2 (here, 500 degrees Celsius) exceeds b = 90 seconds, and if it exceeds 90 seconds, it is determined that the operation is normal.
If it is 90 seconds or less, the process returns to 114 as abnormal. At 128, it is checked whether or not the temperature signal has exceeded T3 (here, 700 degrees Celsius) (ie, whether or not the desired combustion propagation period has passed and the full-scale combustion period has started) (118). The energizing power is reduced from the large ignition power to the combustion maintaining power that is small enough to maintain the combustion continuation, and proceeds to 134 (132). If not, the heating rate for the past minute is a = Check if it exceeds 1 degree Celsius / minute (13
0), if it exceeds, return to 128 as normal operation; if less, return to 114 as abnormal.

At 134, the above T2 (here, 50 degrees Celsius)
It is checked whether the required time t (T2 to T3) from 0 °) to T3 (here, 700 ° C) exceeds b = 90 seconds, and if it exceeds 90 seconds, it is determined that the operation is normal.
If it is 90 seconds or less, the process returns to 114 as abnormal. At 136, it is determined whether or not the reproduction has been completed. That is, it is checked whether or not a predetermined time (here, about 10 minutes later) has elapsed from the detection of T3 (here, 700 degrees Celsius) (step 128), and when the time has elapsed, the power supply to the heater 11 is turned off (140), and the power supply is turned off. After a predetermined time from when the blower 13 is stopped, the valve 12 is closed (14
2) Return to 100.

Steps 112, 118, 120,
Steps 122, 124, 126, 128, 130 and 134 constitute the temperature signal abnormality determining means of the present invention.
Numeral 16 constitutes an energization time control means according to the present invention.
Next, the timer control subroutine of step 116 will be described. In this subroutine, instead of energizing and blowing control using the filter temperature as a parameter, the energizing is uniformly performed using the time from the start of energizing the heater 11 as a parameter.
This is to control the air blowing.
When a (here, three minutes) has elapsed (1161), the air blowing is started (1163). Next, after the heater is energized, the time Tb
After 5 minutes have elapsed (1165), the heater 11
Is switched from ignition power to combustion sustained power (1167). Next, when the time Tc (here, 15 minutes) elapses after the heater is energized (1169), the process proceeds to step 140, and the energization to the heater 11 is stopped.

According to the control method of the present embodiment described above, it is possible to prevent the regeneration of particulates, the erosion and cracking of the filter, and the failure of the control operation due to malfunction or failure of the temperature sensor 6. . That is, step 11
Reference numeral 2 denotes a failure in the temperature sensor 6 or the heater 11 or a control circuit for supplying electricity to the heater 11. Here, the temperature sensor 6
The problem that reproduction cannot be performed due to the defect of the above is eliminated.

Steps 118, 120, 122, 12
4, 128 and 130 indicate that the temperature signal output from the temperature sensor is at a lower level than the true temperature, so that although the input temperature signal is actually lower, the filter is damaged due to the lower temperature. And cracks are prevented from occurring. Steps 126 and 134 indicate that the rate of increase of the temperature signal output by the temperature sensor is higher than the true rate of increase in temperature, so that the input temperature signal is high despite the fact that it is actually lower. Prevention of unburned particulates from occurring due to power supply to the heater 11 being stopped or stopped or erroneous control of the air blowing operation is prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of an exhaust gas purification device of the present invention;

FIG. 2 is a flowchart showing the reproducing operation;

FIG. 3 is a flowchart showing the reproduction operation;

FIG. 4 is a flowchart showing the reproduction operation;

FIG. 5 is a timing chart showing the reproduction mode;

FIG. 6 is a diagram corresponding to claims.

[Explanation of symbols]

Reference numeral 2 denotes a filter, 6 denotes a temperature sensor (temperature detecting means), 8 denotes a controller (control means, temperature signal abnormality determining means, power-on time controlling means), and 11 denotes a heater (electric heating means).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 4-87316 (JP, U) JP-B 63-6737 (JP, B1) JP-B 63-35151 (JP, Y1) (58) Field (Int.Cl. ⁷ , DB name) F01N 3/02-3/038

Claims (3)

(57) [Claims] 1. A filter disposed in an exhaust passage of a diesel engine, temperature detecting means for detecting the temperature of the filter, and burning the particulate collected by the filter by heating the filter. An exhaust gas purifying apparatus, comprising: an electric heating unit that regenerates the filter by means of a filter; and a control unit that causes the electric heating unit to perform the regeneration by controlling energization of the electric heating unit based on a temperature signal output by the temperature detecting unit. The control means includes a temperature signal abnormality determining means for determining whether the input temperature signal is abnormal, and the electric heating means instead of the energization control based on the temperature signal when the temperature signal is determined to be abnormal. Is the power supplied to the ignition power
Control from lowering the combustion maintenance power to a smaller value.
And an energization time control unit for causing the electrothermal unit to perform the regeneration by controlling energization of the electric heating unit using time as a parameter . 2. The exhaust gas purifying apparatus according to claim 1, further comprising: a blower for introducing air for burning the particulates into the filter, wherein the energization time control unit determines that the temperature signal is abnormal. If it is determined that the temperature signal is not normal, the air blower controls the air blower based on the temperature signal to perform the regeneration, and if it is determined that the temperature signal is abnormal, a predetermined air blow to the blower is performed. An exhaust gas purifying apparatus characterized by causing the air blowing means to perform the regeneration by air blowing control in a pattern. 3. The exhaust gas purifying apparatus according to claim 1, wherein the temperature signal abnormality determination unit is configured to determine whether the temperature rise rate of the filter after the start of energization to the electric heating unit is equal to or greater than a predetermined value. An exhaust gas purifying apparatus characterized by determining that a temperature signal is abnormal.