JPH03202610A - Exhaust gas processing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent clog and burnous by stopping the exhaust trap collecting and regenerating operations in the event of failure in an operating condition sensing means, which is used to presume the particulate deposit condition on the exhaust trap. CONSTITUTION:An exhaust trap 101 to collect exhaust particulate is installed on the exhaust passage 100 of an internal combustion engine. The operating condition of the engine is sensed by a means 105, and the regeneration timing of exhaust trap 101 is judged by a means 106 on the basis of the result from sensing. A regeneration control means 107 controls a means 104 to regenerate the exhaust trap by combustion the collected exhaust particulate when judgement is in the regenerative timing. At this time, a failure diagnostic means 108 makes diagnosis of eventual failure of a means 105. In the event of failure, a trouble countermeasure means 109 takes countermeasure for the trouble so that a bypass valve 103 on a bypass 102 for the exhaust trap 101 is opened and that the regenerating operation is stopped. At the same time, an alarm is given from an alarm device 110.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an apparatus for collecting and treating exhaust particulates from an internal combustion engine using an exhaust trap.

(Prior Art) It is well known that an exhaust trap is installed in the exhaust passage in order to collect particulates such as carbon contained in the exhaust gas of a diesel engine (Japanese Patent Application Laid-Open No. 58-1988-1). Publication No. 51235, etc.

The particulates collected in the exhaust trap are automatically combusted depending on the operating conditions of the engine, such as during high load when the exhaust temperature rises, but in normal operating ranges, they gradually accumulate and become part of the exhaust gas. This creates resistance and causes an increase in exhaust pressure (exhaust pressure), which is a factor that adversely affects engine performance.

Therefore, the collected particulates are periodically burned to regenerate the exhaust trap.For this purpose, in the above-mentioned publication, an intake throttle valve is provided in the intake passage, and this intake throttle valve is installed during regeneration. By closing the valve and reducing the amount of intake air, excess air that is not involved in combustion is reduced, and the exhaust temperature is increased to ignite and burn particulates.

(Problems to be Solved by the Invention) Incidentally, in such an exhaust treatment device, regeneration is performed periodically while monitoring the degree of particulate collection based on operating hours, mileage, etc. In order to correctly determine the timing of this regeneration, operating conditions, exhaust temperature,
Various sensors are required to detect exhaust pressure, etc.

However, in this case, it is essential that these sensors are always operating normally, and if they fail, it will not be possible to determine the correct regeneration time, and the exhaust pressure will rise excessively due to the exhaust trap becoming clogged. If a large amount of collected particulates is burned all at once, there is a risk that the trap will burn out due to abnormally high temperatures.

The present invention aims to solve such problems.

(Means for Solving the Problems) Therefore, the present invention provides an exhaust passage 100 as shown in FIG.
An exhaust trap 101 installed in the exhaust trap 101 to collect exhaust particulates, a bypass valve 103 installed in the bypass passage 102 to bypass this exhaust trap 101 and let the exhaust flow, and a bypass valve 103 installed in the bypass passage 102 to raise the exhaust temperature to remove the accumulated particulates in the exhaust trap. A regeneration means 104 for combusting, a means 105 for detecting at least the operating state, a means 106 for estimating the amount of captured and deposited particulates based on the operating state and determining the regeneration time of the exhaust trap 101, and a means 106 for determining the regeneration time of the exhaust trap 101 when the regeneration time comes Control means 107 for operating the regeneration means 104 to regenerate the exhaust trap 101
a failure diagnosis means 108 that determines whether the detection means 105 is functioning normally; and a failure countermeasure means 109 that opens the bypass valve 103 and stops the regeneration operation when it is determined that a failure has occurred. and a failure warning means 110 that also warns of the occurrence of a failure.

(Function) Therefore, when an abnormality is detected in the output of the means for detecting the operating condition and it is determined that there is a malfunction, the bypass valve is immediately opened to flow the exhaust gas into the bypass passage and remove the particulates in the exhaust trap. When the collection is stopped and the regeneration operation is being performed, the operation of the regeneration means is stopped to lower the exhaust gas temperature.

Therefore, it is possible to prevent excessive particulates from being collected in the exhaust trap, resulting in deterioration in drivability due to an increase in exhaust pressure and abnormal combustion in the exhaust trap.

At the same time, it is also possible to warn the driver of a malfunction and encourage inspection and maintenance.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 2, 1 is a diesel engine body, 2 is an intake passage, and 3 is an exhaust passage. The exhaust passage 3 is provided with an exhaust trap 4 for collecting particulates in the exhaust gas. In the exhaust trap 4, a catalyst that oxidizes unburned components in the exhaust gas is coated on the surface of an air-permeable ceramic carrier.

First, an intake throttle valve 5 is installed in the intake passage 2 as a means for raising the exhaust temperature and regenerating the particulates collected and deposited in the exhaust trap 4 in order to periodically burn them.
is provided, and when the opening degree is narrowed down by the negative pressure actuator (diaphragm device) 6, surplus air that does not participate in combustion decreases and the exhaust temperature increases. The negative pressure actuator 6 is equipped with a solenoid valve (three-way solenoid valve) SOL3.
Negative pressure from a vacuum pump (not shown) or the like is introduced through the pump.

The exhaust passage 3 is provided with an exhaust throttle valve 7, and when the opening is throttled via the negative pressure actuator 8, the amount of fuel injected from the fuel injection pump 10 is reduced due to the increase in engine load due to the increase in exhaust pressure. increases, raising the exhaust temperature. The negative pressure applied to the negative pressure actuator 8 is controlled by a solenoid valve 5OLI.

Furthermore, an electric heater 11 is installed just before the exhaust trap 4, and by energizing it, the temperature in front of the trap can be raised.

An exhaust bypass passage 12 is provided in parallel with the exhaust trap 4, and a negative pressure actuator 14 is provided in this bypass passage 12.
A bypass valve 13 that opens and closes via the exhaust trap 4 is installed, and by opening the bypass valve 13 during deceleration of the engine when the exhaust temperature is low, the exhaust trap 4 is bypassed and low-temperature exhaust flows.
A negative pressure actuator that prevents the temperature of the exhaust trap 4 from decreasing].

4, the introduction of negative pressure is controlled via a solenoid valve 5QL2.

Next, the control unit 20 controls the operation of the solenoid valves 5QL1 to 5QL3 and the electric heater 11 to regenerate the exhaust trap 4, and also stops the regeneration operation when an abnormality occurs in various sensors as described later, or This prevents the exhaust trap 4 from being clogged with particulates.

That is, the control unit 20 receives detection signals Ne, Q, T@c from the engine speed sensor 21m, fuel injection amount sensor 21b, engine cooling temperature sensor 21c, etc. as means for detecting the engine operating state. While observing the operating conditions, and based on the output of the pressure sensor 22 that detects the pressure difference ΔP between the upstream and downstream sides of the exhaust trap 4,
The amount of accumulated particulates collected in the exhaust trap 4 is estimated to determine the regeneration timing, and the operating conditions at that time and the upstream and downstream temperatures of the exhaust trap 4 detected by the exhaust temperature sensors 23a and 23b are Based on the exhaust gas temperature, each of the regeneration means is selectively operated to efficiently regenerate the exhaust trap 4.Furthermore, when an abnormality occurs in these various sensors, the regeneration operation is stopped and the exhaust trap 4 is regenerated. clogging avoidance operation and warning lights WLI and WL2.
A warning is given by lighting up.

The above-mentioned control operation when the control unit 20 is configured with a microcomputer will be specifically explained with reference to FIGS. 3 to 10.

Figure 3 shows the main flow of the control operation. First, the engine rotation speed Ne is read, and it is determined from the rotation speed Ne whether the engine is operating completely independently (step 1.2).
However, in the following display, it is simply written as "Sl, 2".

If complete explosion has not occurred, use S3 to close the intake and exhaust throttle valves5.
7 is opened, the bypass valve 13 is also opened, and the electric heater 11 is turned off. Also, turn off the warning lights WLl and WL2.

On the other hand, when it is determined that a complete explosion has occurred, the fuel injection amount Q, the inlet and outlet temperatures TIN and TOUT of the exhaust trap 4, and the pressure difference ΔP between upstream and downstream are read in S4.
The process moves to S5, a failure diagnosis routine for various sensors.

The specific details are as shown in Fig. 4, and this fault diagnosis is performed based on whether the outputs of various sensors are within the normal output range.
Respectively fuel injection amount Q, cooling water temperature Tw, engine speed Ne
, exhaust trap inlet temperature TIN, trap outlet temperature T
OUT, if the differential pressure ΔP across the trap is within the specified range, S
The failure determination flag is turned off in step S27, and if any one of them is not present, it is determined that there is a failure and the flag is turned on in step S28.

Next, returning to FIG. 3, based on this diagnosis result, check whether there is a failure from the judgment flag in S6, and if it is not a failure, the S
After turning off the warning light WL2 at step 7, it is determined from a regeneration time flag whether or not it is time to regenerate the exhaust trap 4, which will be described later (S8).

When it is time for regeneration, the warning light WLI is turned on and regeneration operation begins (S9, 10).

The specific details of the regeneration operation are shown in Figure 7, but since the regeneration conditions vary greatly depending on the operating status of an engine, the key points for efficient regeneration without impairing drivability are shown in Figures 9 and 9. This will be explained with reference to FIG.

The operating range determined from the engine load Q and rotational speed Ne is
As shown in FIG. 9, the driving range is divided into four regions A to D, and the control contents are varied according to the divided operating regions A to D, as shown in (i) to (iv) below.

(i) Region A: In this region, as shown in Fig. 10, the exhaust temperature is higher than the regeneration temperature (approximately 400°C) TRE, so the exhaust trap 4 can be regenerated without doing anything. Do not activate the means.

Note that FIG. 10 shows the exhaust gas temperature characteristics with respect to engine load under a constant rotation speed condition.

(ii) Region B: In this region, the regeneration temperature TREG is not reached unless the exhaust gas temperature is increased to some extent. For this reason,
It is necessary to throttle the intake air with the intake throttle valve 5 or to throttle the exhaust air with the exhaust throttle valve 7.

In this case, in this region B, the load is relatively high and the excess air ratio is small, and it is not a good idea to restrict the intake air because particulates (smoke) will increase dramatically. Therefore, in this region, only the exhaust gas is restricted and the electric heater 11 is turned on. Make it.

(iii) Region C: In this region, the exhaust gas temperature is low and will not reach the regeneration temperature TREG unless the temperature is raised considerably.

Note that in this region, the excess air ratio is large, so even if the intake air is throttled, particulates will not increase.Therefore, both the intake air and the exhaust air are throttled, and the electric heater 11 is turned on.
Make it.

(iv>D region: In a steady state of operation in this region, even if both the intake air and the exhaust gas are throttled and the electric heater 11 is turned on, the regeneration temperature TRE will not be reached.

However, in the case where there is a transitional transition from the high-load, high-speed range to this range, the residual heat in the exhaust trap 4 is high, so if this is used, regeneration can be continued. Therefore, in this region, three regions (T
Area DT where IN≧T1 IN<T and T OUT
If the area is ≧T2, , TIN<T and TOUT<T
The residual heat of the exhaust gas is divided into two regions D3), and when it is possible to utilize the exhaust residual heat, it is actively utilized as described below.

However, T1 is 400°C, which is equal to the regeneration temperature TREG;
2 is 300°C.

Region D1: Since the exhaust gas temperature is high in this region, regeneration continues as it is, but the electric heater 11 is turned on to assist.

Region D2: Since the outlet temperature T OUT of the exhaust trap 4 is lower than the inlet temperature TIN, it can be seen that the exhaust trap 4 is cooled by the exhaust gas, so the exhaust trap 4
By bypassing the flow, the temperature of the trap itself is kept high and the regeneration temperature can be maintained.

Therefore, in this region, the bypass valve 13 is opened and the electric heater 11 is turned on.

In such a low temperature range, no matter what you do, it is impossible to raise the regeneration temperature to the regeneration temperature TRE.However, since there are few particulates generated in such a low temperature range, the exhaust gas may be bypassed and flowed. There is no problem even if it is bypassed, and the exhaust pressure can be lowered by bypassing it.

Therefore, in this region, the bypass valve 13 is opened, and the electric heater 11 is OFF.

FIG. 7 shows a specific routine for performing the operations shown in (i) to (iv) above.

In S51, it is checked whether the cooling water temperature Tw is equal to or higher than a predetermined value (for example, 50° C.), and if it is equal to or higher than the predetermined value, the process proceeds to S52.

First, in 853 to S55, engine load Q and rotation speed Ne
It is determined to which operating range A to D shown in FIG. 3 the operating conditions at that time determined from the above belong. in this case,
The area characteristics shown in FIG. 9 are mapped and stored in the ROM in advance.

Depending on the determination result, if it is area A, step S58. If it is area B, S59. If it is area C, S60. S5 if it is in the area
Proceed to step 6.

In addition, in S 56 and S 57, three temperature ranges D1 to D
, and if it is area D1, S6
1. If it is area D2, S62. If the area is 863
Proceed to.

In S58, reproduction is performed according to the operation contents in area A described above, in S59, area B is reproduced, in S60, area C is reproduced, and furthermore, in S61, area D1 is reproduced, and in S6
In step 2, playback is performed according to the operation details in area D2, and in step 3
At 63, the exhaust gas is bypassed according to the contents of the area.

364 to S67 count the playback time, and then S6
The process proceeds to S69, where the counted playback time is compared with a predetermined time (for example, 10 minutes), and when the predetermined time has elapsed, it is determined that the playback has ended, and the process proceeds to S69.

At step 369, the exhaust and intake throttle valves 5 and 7, the bypass valve 13, and the electric heater 11 are returned to their original states, the regeneration timing flag is turned off, and the PCT quantity product value is reset.

On the other hand, if the cooling water temperature Tw is less than the predetermined value in S51, S
At 70, it is checked whether the inlet temperature TIN of the exhaust trap is T or more, and if TIN≧T1, the exhaust trap 4 is
Since the data will be played back, the process moves to 358, but if not, the process moves to S71 and S72, and no playback operation is performed.

In this way, when the regeneration period is reached, the regeneration means is operated to re-burn the particulates accumulated in the exhaust trap 4, but if this is not the case, the bypass valve operation routine of the Sll is performed as shown in FIG. Transition.

Here, as shown in Fig. 5, the driving state is searched on a map to determine whether it is in a deceleration state or not (S31.532).
During deceleration, if the exhaust outlet temperature T OUT is higher than a predetermined value, the bypass valve 13 is closed; otherwise, the bypass valve 13 is opened and the exhaust gas bypasses the exhaust trap 4, allowing the exhaust trap 4 to flow. Relatively low temperature exhaust (
During deceleration, the exhaust gas temperature is low to prevent overcooling (833-535).

When the outlet temperature is higher than the set value, if the exhaust air is bypassed and flows through the exhaust trap 4, a moderate amount of air (oxygen) remains in the exhaust trap 4, which causes the collected particulates to disappear. Since the exhaust trap 4 may be burnt out due to combustion, in this case, the exhaust gas is actively flowed into the exhaust trap 4 to lower the temperature and prevent burnout.

Next, returning to FIG. 3, the regeneration timing is determined using Si2, that is, it is determined whether a predetermined amount of particulates have accumulated in the exhaust trap 4. The specific content is as shown in Fig. 6, in which the particulate accumulation amount (PCT amount) is integrated based on the output of the operating state detection means, and it is determined whether the integrated value has reached a predetermined value ( 841 to 343), and when it is estimated that a predetermined amount of accumulation has been reached, the regeneration timing flag is turned on to perform the regeneration operation described above, but if not, the process moves to S44 and the differential pressure across the exhaust trap 4 is ΔP is compared with a predetermined value ΔP wax, and if it is larger than this, the reproduction time flag is turned on, and if it is not, the reproduction time flag is turned off (845, 346).

In addition, when determining the regeneration timing, the amount of PCT generated varies depending on the operating conditions, so the amount of PCT is estimated in advance based on the engine load, rotation speed, differential pressure across the exhaust trap 4, etc. It is calculated from the generation characteristics of particulates.

By the way, if the means (various sensors) for detecting the operating state are not monitored to see if they are operating properly, the particulates accumulated in the exhaust trap 4 will not be correctly grasped, and the exhaust trap 4 will not be properly detected. If excessive particulates accumulate in the exhaust trap 4, they may become clogged and the exhaust pressure may rise excessively, or depending on the operating conditions, they may burn out, causing the exhaust trap 4 to become abnormally hot and burn out.

Therefore, when a failure is determined in the operating state detection means etc. at 86 in FIG. 3, the process moves to the failure operation routine at 313, and as shown in FIG. 8, the intake and exhaust throttle valves 5.6 are opened. At the same time, the bypass valve 13 is opened and the electric heater 11 is turned off. Warning light WL1 is then turned off, but WL2
flashes to warn the driver of the occurrence of a malfunction (S80
).

When the intake and exhaust throttle valves 5.7 are opened and the electric heater 11 is turned off, the exhaust temperature does not rise, regeneration in the exhaust trap 4 is stopped, and at the same time, the exhaust trap 4 is bypassed and the exhaust is allowed to flow. During this time, prevent further collection of particulates. These results
By preventing the exhaust trap 4 from clogging, it is possible to avoid deterioration in drivability and the risk of burnout due to abnormal combustion.

Note that if the regeneration time has not been reached at the time of this failure determination, the integrated value of the PCT amount calculated at 342 in FIG. 6 does not pass through the flow of S42 at the time of failure, so the state before the failure is stored.

In addition, if the regeneration time has been reached, the regeneration time flag is turned on in S45, and when a failure is determined, the regeneration time flag is turned on.
Since the flow from to S46 is not passed, the playback timing flag is stored with it turned on.

As a result, when the fault condition is resolved, the next operation will be continued based on this memorized result. Therefore, control after fault recovery is performed accurately, prevents deterioration of drivability, and improves exhaust gas. The trap 4 can be appropriately protected.

(Effects of the Invention) As described above, according to the present invention, it is constantly monitored whether or not an abnormality has occurred in the output of the operating state detection means used to estimate the particulate accumulation state in the exhaust trap. However, in the event of an abnormality, the particulate collection operation of the exhaust trap is stopped, and the regeneration operation is also stopped. This prevents the exhaust trap from clogging and deterioration of drivability. It is also possible to avoid the danger of the trapped particulates burning out and damaging the trap.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a schematic block diagram of an embodiment of the present invention, Figs. 3 to 8 are flowcharts showing control operations, and Fig. 9 shows engine load and rotation. FIG. 10 is an explanatory diagram showing the control range during regeneration operation based on numbers, and FIG. 10 is an explanatory diagram showing the same control range based on engine load and exhaust temperature. l... Engine body, 2... Intake passage, 3... Exhaust passage, 4... Exhaust trap, 5... Intake throttle valve, 7...
...Exhaust throttle valve, 11...Electric heater, 12...Exhaust bypass passage, 13...Bypass valve, 20...Control unit, 21m...Rotational speed sensor, 21
b...Fuel injection amount sensor, 21c...Cooling water temperature sensor, 22...Pressure sensor, 23a, 23b=-exhaust temperature sensor, WLl, WL2...Warning light. Figure 4 Figure Figure 9 Figure 0

Claims (1)

[Claims] An exhaust trap installed in the exhaust passage to collect exhaust particulates, a bypass valve installed in the bypass passage to bypass this exhaust trap and allow the exhaust to flow, and increase the exhaust temperature to burn the accumulated particulates in the exhaust trap. a regeneration means; a means for detecting at least an operating state; a means for estimating the amount of captured and deposited particulates based on the operating state to determine when to regenerate the exhaust trap; and when the regeneration time comes, the regeneration means is operated. a control means for regenerating the exhaust trap; a failure diagnosis means for determining whether the detection means is functioning normally; and when it is determined that a failure has occurred, the bypass valve is opened and the regeneration operation is stopped. 1. An exhaust gas treatment device for an internal combustion engine, comprising a failure countermeasure means for warning of the occurrence of a failure, and a failure warning means for warning of the occurrence of a failure.