JPH0137139Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an exhaust purification device for a diesel engine.

(Prior art) As an exhaust purification device for a diesel engine, a heating device is provided upstream of a filter member (particulate trap) provided in the exhaust passage, and a temperature sensor is provided inside the filter member.
A device is known in which the operation of a heating device is controlled based on a signal from a temperature sensor (see, for example, Japanese Utility Model Application No. 57-95414). This thing is
When the heating device burns and removes particulates in the exhaust gas collected by the filter member, the heating device is not activated when the exhaust temperature is high to prevent abnormal temperature rise of the filter member. .

(Problem that the invention aims to solve) By the way, filter members include wire mesh-like materials and honeycomb-like materials integrally molded with ceramics, etc., but it is difficult to install a temperature sensor inside the filter member. There are cases. In other words, in the case of something like the wire mesh mentioned above, if the density is low, it may be possible to insert a temperature sensor into the filter member from the side, but with a honeycomb-like material, the filter is usually extruded and fired. In order to make it a component,
It is difficult to form the mounting hole for the temperature sensor in post-processing, and even if processing is performed before firing, dimensional errors are likely to occur in the mounting hole. In other words, if the mounting hole is small, the temperature sensor cannot be inserted, and if the mounting hole is made larger in advance, it will be easier to insert the temperature sensor, but the temperature sensor and filter member will This creates a gap between the two and increases the amount of exhaust gas that escapes.

Therefore, in the case of a honeycomb-shaped filter member, it is conceivable to provide a temperature sensor between the heating device and the filter member, for example. However, the exhaust gas temperature distribution in the exhaust passage is uneven due to factors such as the shape of the exhaust passage, and heating equipment using burners may have poor mixing of the combustion gas and exhaust gas, making it difficult to control the heating equipment. Accurate temperature detection becomes difficult.

(Means for Solving the Problems) As a means for solving the above problems, the present invention provides a honeycomb filter member made of a porous material that collects particulate components in the exhaust gas in the exhaust passage of the engine. A diesel engine having a configuration in which a heating device for burning and removing particulate components collected by a filter member is provided upstream of the filter member, and the operation of the heating device is controlled in response to a detection signal from a temperature sensor provided in an exhaust passage. In the exhaust purification device, a baffle plate is provided downstream of the heating device and between the exhaust gas inlet upstream of the filter member and the filter member, and the temperature sensor is disposed between the buffle plate and the upstream end surface of the filter member. The present invention provides an exhaust purification device for a diesel engine characterized by the following features.

(Function) In the above exhaust gas purification device, the baffle plate causes turbulence in the flow of exhaust gas, thereby mixing the low-temperature part and the high-temperature part of the exhaust gas, and when the heating device is in operation, the heated gas and the exhaust gas are mixed. I will be doing some mixing. This results in
On the downstream side of the baffle plate, the temperature distribution of the exhaust gas is made uniform, and the temperature sensor detects the uniform temperature of the exhaust gas supplied to the entire filter member.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In the exhaust purification device 1 for a diesel engine shown in FIG. 1, reference numeral 2 denotes an exhaust purification means interposed in the middle of the exhaust passage 3, and a cylindrical partition plate 6 is provided in the front cylinder 5 of the split casing 4. An exhaust gas introduction chamber 7 is formed between the front cylinder 5 and the partition plate 6, a mixing chamber 8 for mixing flame and exhaust gas (described later) is formed inside the partition plate 6, and a filter member is installed in the rear cylinder 9. 10 is housed therein, and a burner type heating device 12 is connected to the upstream end of the front cylinder 5 via a combustion cylinder 11.

The exhaust passage 3 is connected to the exhaust gas introduction chamber 7 at an exhaust gas introduction port 13 that is open on the side surface of the exhaust gas introduction chamber 7, which is located downstream of the heating device 12 and upstream of the filter member 10. This exhaust passage 3
has a casing 4 containing a filter member 10.
A bypass passage 14 is provided for bypassing the air, and a valve 15 is provided in the bypass passage 14.

Further, a truncated conical first buff-full plate 16 whose apex side projects into the mixing chamber 8 is provided at the connection portion between the front cylinder 5 and the combustion cylinder 11 of the casing 4. On the downstream side of the port 13, there is a second
A front plate 18 and a rear plate 1 in which a full plate 17 is annular
It is attached by being clamped with 9. and,
An introduction chamber 20 is formed between the second baffle plate 17 and the upstream end surface of the filter member 10, and a temperature sensor 21 is provided facing the introduction chamber 20.

The filter member 10 is formed of a heat-resistant porous material into a honeycomb shape, and every other pore extending along the flow direction of the exhaust gas is closed at its end with a blind plug 22 . Exhaust gas flows in through pores that are open on the upstream side (closed on the downstream side) and flows out through pores that are open on the downstream side through an air-permeable porous partition. Particulate components such as carbon particles are now collected.

The heating device 12 includes a fuel injection nozzle 24 attached to a support tube 23. The fuel injection nozzle 24 has its fuel injection center line aligned with the filter member 1.
The filter member 10 is disposed so as to face the center of the upstream end surface of the filter member 10 so that the center line of the exhaust gas flow at 0 coincides with the center line of the exhaust gas flow. A fuel supply pipe 25 is connected to the fuel injection nozzle 24, and a primary air supply port 27a and a secondary air supply port 27b are opened, and a tertiary air supply port 27c is opened in the support tube 23. , an air supply passage 29 extending from the pump 28 is connected to each of the air supply ports 27a to 27c, and a branch passage 2 connected to the tertiary air supply port 27c is connected to each air supply port 27a to 27c.
A valve 30 is provided at 9a. Further, a spark plug 31 is attached to the support tube 23 on the downstream side of the fuel injection nozzle 24 .
In the case of this example, the fuel injection nozzle 24 is of a solenoid valve type, and the operation of the solenoid valve 32 allows the injection of fuel and the supply of primary air and secondary air to be stopped simultaneously.

The partition plate 6 has a diameter that expands conically toward both sides with the minimum diameter at the upstream side of the longitudinal center, and a plurality of ventilation holes 33 are provided in the expanded diameter portions on both sides around the entire circumference. are equally distributed. Also,
A plurality of communication holes 3 are also provided in the first full plate 16.
4 are evenly spaced around the entire circumference of the plate. On the other hand, the second baffle plate 17 has a plurality of communication holes 35 arranged in an annular manner at a predetermined interval around its periphery. Each of the communication holes 35 of the second baffle plate 17 is located at a position where a line connecting the centers of the communication holes in an annular shape divides the introduction chamber 20 into an area ratio of 1:1 in the cross section.

In addition, a combustion chamber 3 formed by a combustion tube 11
6 includes a constriction portion 38 formed by a ring member 37 at the center in the longitudinal direction. This constriction section 38 is for once constricting the flame from the heating device 12 to shorten the flame length and make the entire device smaller.

Therefore, the operation of the heating device 12, that is,
The operation of the electromagnetic valve 32, the pump 28, and the valve 30, and the operation of the valve 15 in the bypass passage 14 are centrally controlled according to a detection signal from a fuel flow meter 39 that measures fuel consumption and a detection signal from the temperature sensor 21. It is controlled by a device 40.

The mode of control in the central control unit 40 is shown in a flowchart in FIG. 2. First, upon the start of operation, initialization such as clearing of the memory is performed in step 41.

Next, in step 42, the fuel flow rate signal W from the fuel flow meter 39 is input, and in step 43, the current fuel flow rate _W is integrated with respect to the previously integrated fuel flow rate integrated value Wp: W _p +W→W _p will be carried out. Then, in step 44, it is determined whether the integrated value _Wp is larger than a preset reference value T. Here, to explain the reference value T, the amount of particulate components collected by the filter member 10 increases as the fuel flow rate increases, that is, as the operating time of the engine increases, and when the fuel flow rate reaches a predetermined value, the filter member 10 There comes a time when the member 10 becomes clogged. The above reference value T is the filter member 10
This corresponds to the fuel flow rate at which clogging occurs. Therefore, if the determination at step 44 is NO, it is assumed that it is not time for the filter member 10 to become clogged, and the process returns to step 42 to continue integrating the fuel flow rate.

On the other hand, if the determination at step 44 is YES,
Assuming that the time has come for the filter member 10 to become clogged, the process advances to step 45, where the temperature sensor 2
A temperature signal detected by 1 is input. If it is determined in step 46 that the detected temperature T is lower than the temperature (approximately 600°C) at which the particulate components such as carbon deposited on the filter member 10 can self-combust, the process proceeds to step 47 and the heating device is activated. A signal is output. Then, in step 48, it is determined whether the detected temperature T is greater than the reference temperature _Tp . In this case, the reference temperature is the lower limit temperature (approximately 600° C.) at which the particulate components can be combusted in the filter member 10. If the determination in step 48 is YES, it is assumed that the filter member 10 is being regenerated, and the process proceeds to step 52, where the integrated value is canceled W _p →0, and then the process returns to step 42. On the other hand, the judgment at step 48 is
If NO, it is determined that the filter member 10 will not be regenerated and the process proceeds to step 49, where a warning activation signal is issued and an alarm is issued, and furthermore, the heating device operation is stopped (cut) at step 50, and the central control The device 40 is then stopped.

If it is determined in step 46 that the detected temperature T is higher than the self-combustion temperature t, the process proceeds to step 51, where it is determined whether the self-renewable temperature state continues for a certain period of time. If this judgment is NO, the process proceeds to step 47, and if YES, it is assumed that self-regeneration has been completed, and the process proceeds to step 52, where the integrated value is canceled W _p →0.

Although not shown in Figure 2 above,
In the central control device 40, when the heating device activation signal is output, an activation signal to open the valve 15 of the bypass passage 14 is output, and the valve 15 is opened half-way to allow 1/2 of the exhaust gas to flow.
2 volumes will flow through the bypass passage 14.

Next, to explain the operation of the above embodiment, the pump 28 and the solenoid valve 32 are in a non-operating state until an activation signal is output from the central controller 40, and the bypass passage 14 and the air supply passage 29 are in a non-operating state. When the valves 15 and 30 are also closed, the entire amount of the exhaust gas is discharged through the filter member 10, and particulate components in the exhaust gas are collected and deposited on the filter member 10. To go.

On the other hand, signals are outputted from the fuel flow meter 39 and the temperature sensor 21 to the central controller 40, and the central controller 40 performs control according to the flowchart shown in FIG. That is, when it is determined that the integrated value of the fuel flow rate exceeds the reference value based on the signal from the fuel flow meter 39 and the exhaust gas temperature has not reached the self-renewable temperature of the filter member 10 based on the signal from the temperature sensor 21. , a valve opening activation signal for the valve 15 of the bypass passage 14 is output together with the heating device activation signal. As a result, the electromagnetic valve 32 is activated and fuel is injected, and the pump 28 is activated and the valve 3 of the air supply passage 29 is activated.
The valve is opened at 0, air is supplied, and ignition is performed by the spark plug 31, while half of the exhaust gas passes through the filter member 10.

The fuel in the fuel injection nozzle 24 is mixed with air from the primary air supply port 27a, atomization is promoted by the air from the secondary air supply port 27b, and the fuel is injected from the fuel injection nozzle 24 to the spark plug 3.
Ignition by 1 is performed. ignited combustion gas,
In other words, the combustion of the flame is further promoted by the air from the tertiary air supply port 27c, and the flame passes through the constriction part 38 of the combustion chamber 36, and is evenly dispersed throughout the combustion chamber 36 and mixed. room 8
Enter. Then, in the mixing chamber 8, the flame mixes with the exhaust gas and burns, and then enters the combustion heat introduction chamber 20 evenly from the entire circumference via the second round plate 17, uniformly heating the entire filter member 10. The particulate components will be removed by combustion. In this case, since the mixing chamber 8 is kept warm in the exhaust introduction chamber 7, the flammability of the flame is high, and
A good heating effect can be obtained with less fuel by mixing the flame and exhaust gas.

When the heating device 12 is operated and the exhaust gas is partially bypassed normally, the temperature detected by the temperature sensor 21 is higher than the reference temperature, and the filter member 10 is regenerated. On the other hand, the heating device 12
If there is an abnormality in the operation of the valve 15 and no flame is generated, or if there is an abnormality in the operation of the valve 15 and the entire amount of exhaust gas flows into the filter member 0, the temperature detected by the temperature sensor 21 will be lower than the reference temperature. When the temperature becomes low, an alarm is issued and the operation of the heating device 12 is stopped.

Further, when the temperature of the exhaust gas rises to a temperature at which the filter member 10 can self-regenerate due to high-load operation of the engine, and this state continues for a predetermined period of time, the central controller 40 determines that the filter member 10 has self-regenerated. The integrated value of the fuel flow rate is canceled, and unnecessary operation of the heating device 12 is eliminated.

In the above embodiment, the operating interval of the heating device 12 is basically controlled by the fuel flow rate, and the temperature sensor 21 is used to ensure control.
However, the basic control described above may be performed using other parameters related to the operating time of the engine, such as vehicle travel distance, other than the fuel flow rate. Furthermore, since the amount of particulate components generated in the exhaust gas tends to increase as the engine speed increases, the rotation sensor 55 as shown by the chain line in FIG.
The output signal from the heating device 12 may be inputted to the central control device 40, and the operating time of the engine, that is, the fuel flow rate may be corrected to increase as the engine speed increases, thereby shortening the operation interval of the heating device 12. good.

Further, as the heating device, in addition to the burner type in the above embodiment, a heater type using a heating wire may be adopted. In this case, the temperature sensor needs to be provided downstream of the heating wire.

(Effect of the invention) Therefore, according to the invention, a buttful plate is provided downstream of the heating device and between the exhaust inlet upstream of the filter member and the filter member, and the upstream end surface of the buttfull plate and the filter member Since a temperature sensor is installed between the filter member and the filter member, it is possible to use the mixing action of the full plate to maintain the appropriate temperature for controlling the operation of the heating device. It becomes possible to detect accurately.

[Brief explanation of drawings]

The drawings illustrate embodiments of the present invention; FIG. 1 is an overall configuration diagram of an exhaust purification device, and FIG. 2 is a flowchart showing a control mode. 1...Exhaust purification device, 3...Exhaust passage, 8...
Mixing chamber, 10...Filter member, 12...
...Heating device, 15...Exhaust inlet, 17...Second
Batsuful plate, 21...Temperature sensor, 39...
...Fuel flow meter, 40...Central control unit.

Claims (1)

[Scope of utility model registration request] A honeycomb-shaped filter member made of a porous material is provided in the exhaust passage of the engine to collect particulate components in the exhaust gas, and a heating device is provided upstream of the filter member to burn and remove the particulate components collected by the filter member. In an exhaust gas purification device for a diesel engine configured to control the operation of the heating device in response to a detection signal from a temperature sensor installed in the exhaust passage, the filter member is connected to an exhaust inlet downstream of the heating device and upstream of the filter member. 1. An exhaust gas purification device for a diesel engine, characterized in that a buff-full plate is provided between the buff-full plates, and the temperature sensor is disposed between the buff-full plate and an upstream end face of a filter member.