JPS6067713A - Device for collecting exhaust particles of internal- combustion engine - Google Patents

Abstract

PURPOSE:To make the period of regeneration of a trap for collecting exhaust particles, by setting the outlet pressure of the trap on the basis of the revolution speed of an engine and the load thereupon, and judging from the ratio of the set outlet pressure to the inlet pressure of the trap whether the trap needs to be regenerated or not. CONSTITUTION:When an exhaust particle collecting trap A provided in an exhaust passage has reached a prescribed state of collection, a burner B is put into operation to burn up collected particles to regenerate the trap A. A sensor C, which detects the revolution speed of an engine, a sensor D, which detects the load upon the engine, and a sensor E, which detects the inlet pressure P1 of the trap A, are provided. The outlet pressure P2 of the trap is set by a means F on the basis of the detected revolution speed and the detected load. It is judged by a regeneration time detection means G in terms of the ratio of the set outlet pressure P2 of the trap A to its inlet pressure P1 whether the trap needs to be regenerated by the burner B. The operation of the burner B is controlled depending on the result of the judgment.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an exhaust particulate collection device for collecting particulates containing carbon as a main component contained in the exhaust gas of an internal combustion engine such as a diesel engine.

Conventional technology In a collection device that collects exhaust particulates using a trap installed in the exhaust passage, the above-mentioned tubes tend to become clogged, and the particles cannot be collected in normal operating ranges except for high-load operation. Since it is difficult to naturally incinerate the collected particles, it is necessary to regenerate the trap by forcibly incinerating the collected particles by burning a burner attached to the trap when a predetermined collection state is reached.

Fig. 1 shows an example of the configuration of a conventional exhaust particulate collection device equipped with this kind of regeneration device, in which ① indicates a trap for collecting exhaust particulates, 2 indicates a fuel injection nozzle constituting a regeneration burner, and 3 is a glow plug for igniting the burner, 4 is a fuel tank, 5 is a fuel pump, 6 is an air pump, 7.8 is a solenoid valve for the fuel system and air system, respectively, 9 is a control circuit, 1
0 is a differential pressure detector, and this differential pressure detector 10 has a pressure outlet 11 on the population side of the trap 1 and a pressure outlet 1 on the outlet side.
Trap inlet pressure and trap outlet pressure are introduced from 2 and 2, respectively, and the differential pressure between the two is detected. When this differential pressure reaches a predetermined value, it is assumed that the trap 1 has reached a predetermined collection state, and the regeneration burner is started to operate (Japanese Patent Laid-Open No. 115809/1983). Reference) 6 However, in reality, the differential pressure before and after trap 1 is
The above differential pressure rFtJ+ is affected not only by the magnitude of the trap 1's collection amount but also by the magnitude of the exhaust gas current, that is, by changes in the amount of intake air depending on the operating state of the engine and the presence or absence of exhaust gas recirculation. This makes it difficult to accurately determine the state of collection. Therefore, in the above-mentioned conventional configuration, the regeneration of the trap is delayed, leading to an excessive increase in the exhaust pressure of the engine, resulting in deterioration of drivability. There were various problems such as burning out the burner fuel, and conversely regenerating it too quickly, resulting in wasted burner fuel.

On the other hand, if we try to detect the trap collection state more accurately based on the trap inlet pressure and trap outlet pressure, it becomes necessary to separately detect the trap inlet pressure and the trap 1 inlet side, and in the end, the two pressures are It is necessary to install a sensor (for example, Tokuwa No. 58-1127), which is significantly more expensive than detecting the differential pressure with a single pressure sensor as shown in Figure 1. It is highly accurate and reliable as a seven-part pressure sensor.

If you try to use something with excellent durability, it will become a fairly expensive part, and the impact on cost will be extremely large.

Purpose of the Invention The present invention was made in view of the above-mentioned conventional problems, and its purpose is to accurately trap a trap in a predetermined collection state without being affected by the magnitude of the exhaust gas flow rate. To provide an exhaust particulate collection device that can perform regeneration,
Furthermore, the object is to realize highly accurate detection of the collection state using one pressure sensor.

Structure of the Invention The exhaust particulate collection device for an internal combustion engine according to the present invention includes a second
As shown in the figure, a trap A for collecting exhaust particulates interposed in the 4JP air path, and a burner B that regenerates the trap A by incinerating the particulates collected in the trap A. A rotation speed sensor C detects the rotation speed of the engine, a load sensor D detects the load of the engine, a pressure sensor E detects the inlet pressure P of the trap A, and the rotation speed sensor C and the load sensor D Trap outlet pressure setting means F for setting trap outlet pressure P2 based on the output signal
and a regeneration timing determining means G for determining whether or not regeneration by the burner B is necessary based on the ratio between the set trap outlet pressure P and the trap population pressure P detected by the pressure sensor E. Prepared and configured.

Function of the Invention Trap AK for collecting exhaust particles is generally characterized by a laminar flow meter, and has the same flow path resistance as trap A! If the amount of collected exhaust particulates is constant, the gas flow rate and trap inlet pressure P1, the gas flow rate and trap outlet pressure P2, and the gas flow rate and the differential pressure across the trap ΔP (ΔP=p, -, p2), respectively. There is an almost proportional relationship.

Therefore, for a given collection needle, the trap population pressure P.

and the trap outlet pressure P2, such as P 2/P + or ΔP/P.

The value of R is approximately constant regardless of the gas flow rate. FIG. 3 shows, for example, the correlation between the trap inlet pressure Pl and the differential pressure ΔP across the trap. t, 6Ratio of both ΔP/P.

When the value reaches a predetermined value, as shown in Figure 4, it always reaches the predetermined collection needle.If trap A is regenerated based on this n7, it will always reach the predetermined collection needle at the appropriate time. It can be regenerated.

On the other hand, the outlet pressure P2 of trap A is as shown in FIG.
Even if the amount of collection increases and the inlet pressure P1 increases, there is almost no change; in other words, it remains at a predetermined value depending on the engine operating conditions regardless of the amount of collection.

Therefore, in this invention, only the trap population pressure P1 is detected by one pressure sensor E, and the trap outlet pressure P2 is set based on the output signals of the engine rotational speed sensor C and the load sensor D. , and P2, a ratio between the two, such as p2/p1 or ΔP/P, is calculated, and whether or not regeneration is necessary is determined based on the magnitude relationship between the calculation result and the set value.

Further Embodiment FIG. 6 is a configuration explanatory diagram showing a specific embodiment of the exhaust particulate collection device according to the present invention, in which 21 is an exhaust passage of an internal combustion engine, and 22 is a part in the middle of this exhaust passage 21. A trap case 23 is provided with a no-nikum type trap installed in the trap case 22 via a cushioning material 24,
25 indicates a trap regeneration burner provided upstream of this trap 23. The trap 23 is
It has a large number of honeycomb-shaped holes, and some of the holes are open on the inlet side and closed on the outlet side, and the remaining holes are closed on the inlet side and open on the outlet side. The structure is such that the exhaust gas collects fine particles when it passes through the walls of each hole.

In addition, the above-mentioned nozzle 25 has a large number of exhaust gas introduction holes 2 on the peripheral wall.
6a, a backflow type evaporator 27 located within the combustion tube 26 and having a flame outlet 27a needle, a mixture jet pipe 28 facing the backflow type evaporator 27, and a It is composed of an O'F Tenkawa glow plug 29 facing near the flame jet port 27a.A fuel supply I#31 extending from an electromagnetic fuel injection valve 30 is connected to the mixture jet pipe 28. Furthermore, fuel (the same fuel as the engine fuel, for example, light oil) is introduced from the fuel tank 32 to the 'AM type fuel injection valve 30 via the fuel pump 33. In the middle of the air supply pipe 31, an air supply pipe 36 is connected which communicates with the discharge port 34b of the air pump 34 via a magnetic three-way valve 35. In the state, the discharge port 34.b of the air pump 34 is communicated with the suction port 34a to release air, and in the energized state, the discharge port 34.b of the air pump 34 is communicated with the air supply pipe 36 to supply air from the air pump all to the burner 25. It has the same configuration.

Therefore, the operation of the burner 25 is controlled by the electromagnetic three-way valve 35 and the fuel pump 33. It is controlled by a fuel injection valve 3o and a glow plug 29. The above electromagnetic three-way valve 35. The fuel pump 33 and the fuel injection valve 3° are respectively energized and controlled by a grounding bag w51 mainly composed of a power transistor of a control device (b), which will be described later. Each operates when energized. Also includes 29 glow plugs and 53 normally open relays.
is connected to the battery 52 via the relay 5.
3 is also a trap that is closed when grounding is performed by the grounding device 51.

On the other hand, a pressure outlet 37 is provided in the trap case 22 and on the inlet side of the trap 23,
A detection section of a pressure sensor 39 is connected to this pressure outlet 37 via a diaphragm 38 for blocking exhaust heat and moisture. As this pressure sensor 35), for example, the illustrated potentiometer type or semiconductor type pressure sensor is used, and its output pressure 'VP is inputted to the control device f50.

Further, on the inlet side of the trap 230, a temperature sensor 4 ( ) consisting of a thermocouple or the like is provided facing the center of the end face of the trap 23 .
It is input at t'50.

Furthermore, 41 is a rotational speed sensor for detecting the rotational speed of the engine, and 42 is a load sensor for detecting the load on the engine. For example, in a diesel engine, the load sensor 42 is composed of a potentiometer that detects the rotational position of a control lever 43a of a heat injection pump 43. These detection signals are also input to the control device 50 in the same way.

The control device * 5rl is the 02 port 54 and this CPU 54.
A memory (ROM) 55 in which control programs and predetermined data are written, and a pressure sensor 7'')-3 (D output information: I
E.V.P.

Output voltage VT of temperature sensor 4(), F-V converter 5h
A multiplexer 5γ that selects any one of the detection signals VL from the R2 load sensor 42, and an A-D converter 5 that converts the selected analog data into digital data. the above-mentioned grounding device 51, and the above-mentioned multiplexer 57, A
-D converter 58. Grounding device 5" and C, the P engineering O (Perife, the above-mentioned C
The PU 54 instructs a channel to the multiplexer 57 via the PIO 59, and after receiving an EOC signal from the AD converter 58 indicating completion of conversion, digitally converted data is input.

The grounding device 5] has four grounding control circuits 51a to 51d mainly composed of power transistors, each of which has a fuel pump 33. Fuel injection valve 30. Electromagnetic three-way valve for air control35. The ground wire of relay coil 53a of relay 53 for glow plug 29 is connected, and P work 05!1
When a signal is sent from the CPU 54 through the terminal 1, the circuit is grounded and each device is activated.

Next, FIGS. 7 to 11 are flowcharts showing a control program in the control device 50, and the operation of the exhaust particulate collector # will be explained according to this flowchart. , S1 to S75 indicate each step of the flowchart.

First, FIG. 7 is a flowchart showing an overview of control.
The same rotational speed signal VR is stored in the memory section (RAM) of the CPU 54 using Sl.
) in the memo IJ-1, S2 to determine whether the engine has started or not, specifically the one-rotation speed, for example] 5 (Determine whether or not it is 1 rpm or more, and if No, return to 81. YES
In the case of S3, the load signal V T, fCPU 54
memory in the memory unit ('RAM). On the other hand, ROM5
The trap outlet pressure P2 corresponding to the engine rotational speed and load is stored in advance as a signal VP2 in S5 and S4.
Then, the ROM 55 is searched for the signal VP2 corresponding to the rotation speed signal VR and the load signal VL. Next, S
5, the output signal of the pressure sensor 39, that is, the trap inlet pressure P
The output signal ■P corresponding to 1 is memorized. and,
VP”-VP in S6.

V.P.

(KO) is calculated, and in S7 it is determined that this is the first time after the start of the beach or after the trap 23 has been regenerated. C, Y to determine whether K (Ko) has reached a predetermined value (Kmax) corresponding to a predetermined collection
In the case of E'S, proceed to S12 and operate the -ner 25, and in the case of NO, use the Sll to read the RAM of the C!PU54.
Write K in (denoted as K') and return to Sl.

If the engine speed is above the predetermined rotation speed, the process will proceed to S7 again, but since S7 is not the first judgment, from the second time onwards, the process will proceed to S8.
Proceed to. In S8, the current ratio K.

A weighted average value is calculated using the previous ratio and ', and the comparison is made with a predetermined value Kmax using SIO as the determination ratio.

The determination after the 22nd press is based on a weighted average to determine if there is a sudden pressure change.

Next, the burner control program in S5 will be explained based on the flowchart of FIG. First, in S21, it is determined whether the engine is started normally, and for example, if the engine is started at 500 rpm.
If it is less than m, the process proceeds to S29, the glow plug 29 is deactivated, and the burner 25 is deactivated in S35, and then the process returns to 81. If YES'''C in S21, the glow plug 29 is activated in S22, and in order to raise the temperature to the temperature required for ignition, it is determined in 823 whether a predetermined time (for example, 50 seconds) has elapsed, and when the predetermined time has elapsed, the process proceeds to 824. proceed cS2
At 4, the temperature immediately before ignition is changed to the output 'V' of the temperature sensor 40.
After storing To in the RAM of the CPU 54, S25
The ignition operation of the burner 25 is performed with.

The ignition operation of the burner 25 is performed according to the program shown in FIG. That is, in S4] it is determined whether the engine is started, for example, whether the engine speed is 500 rpm or more,
If No, proceed to 829 in Figure 85; if Yes, turn on the electromagnetic three-way valve 35 for air supply in S42,
At S43, the fuel pump 33 starts operating.

Then, in S44, based on the rotational speed signal VR and the load signal VL, a drive signal for the fuel injection valve 30 (given as a duty signal, for example, when the frequency is 25H2, 1
Is the valve opening time within the cycle 40? F+ See-Qsec
In step S45, this drive signal is amplified (for example, by doubling the valve opening time) to facilitate ignition. After that, the fuel injection valve 30 is operated at 846 to start fuel supply, and the process proceeds to 326 in FIG. This ignition operation continues until the burner 25 is ignited as described below, but if the engine stops midway, S4
1, the glow plug 29 is deactivated, and the burner 25 is deactivated in step S35.

As shown in FIG. 10, this burner operation stop at 835 involves stopping the fuel pump 33 in S51, stopping the fuel injection valve 3 (J) in S52, and turning the electromagnetic three-way valve 35 into the
This is done by stopping the air supply as an FF.

After the above-mentioned ignition operation, the output VT of the temperature sensor 40 is read in S26, and the temperature rise ΔT is determined from the difference between the temperature signal 'VTo just before ignition and the current temperature signal VT (ΔVT=VT−VTo). In S27, it is determined whether the burner 250 is ignited depending on whether this temperature increase ΔT is greater than or equal to a predetermined value. NO
In this case, if the predetermined wetness difference has not been reached, proceed to 828, and determine whether a predetermined time, that is, the maximum time necessary to reach a temperature difference that can be determined as ignition (for example, 10 seconds) has elapsed, N.

If so, return to S25 and repeat the ignition operation and ignition determination, and if YES, that is, the predetermined temperature difference has not been reached even after 1 () seconds have passed, proceed to S29 and stop the operation of the glow plug 29 and burner 256S27 If YES is determined to be a slight ignition, the process advances to S30 and the temperature sensor 4 (
Is the temperature of burner 25 stable combustion from the output VT of 1? M,
Determine if the trap is greater than If (for example, 500℃), and
In the case of o, it is determined in S33 whether a predetermined temperature (for example, 40 seconds) has passed after ignition. If NO in this S33, S2
Return to step 5 and repeat the control until the predetermined time has elapsed.
), the process proceeds to S34 to stop the energization of the glow plug 29, and after deactivating the burner 25 in S35, the process returns to 81. If the answer is YES in S30 and the stable combustion temperature of the burner 25 is reached within the switching time, the process proceeds to S31, where the combustion control of the burner 25, that is, the temperature control is performed so as to regenerate the trap 23. And S32
In step S31, it is determined whether a predetermined regeneration time (for example, 3 minutes) has elapsed since the start of regeneration of the trap 23, and if No, the control of the burner 25 is cascaded until the predetermined time has elapsed, and if Y E; If S, proceed to S35 and return to MKSIK with burner 25 set to non-attack l.

The temperature control in S31 is performed according to the flowchart shown in FIG. First, in S61, it is determined whether the engine is started, for example, whether the engine is running at 500 rpm or higher, and NO is selected.
If so, return to 834 in Figure 8, and if YES, go to S62.
Proceed to. In this S62, the rotational speed signal vR and the load signal VL are
Based on this, a drive signal for the fuel injector 30 corresponding to the operating conditions is retrieved from the memory 55, and the process proceeds to S63.eS6:i determines that the inlet side gas temperature of the trap 23 is determined from the output VT of the temperature sensor 40. Regeneration lower limit temperature (e.g. 55
If the temperature is below the lower limit temperature, the glow plug 29 is heated by electricity again to assist combustion in S64.

Of course, this also applies if the temperature drops below 550°C during playback.

The glow plug 29 is energized and heated. And S
Proceeding from 64 to S65, the drive signal for the fuel injection valve 30 is amplified (for example, the valve opening time is increased by 1.6 times), and in 866, the drive signal is increased to 550°C for a period of time after the detected temperature exceeds 500°C or during regeneration. It is determined whether the time since the time has reached a predetermined time (for example, 15 seconds). N in S66
If o, proceed to S75, continue to operate the fuel injection valve 30 with the drive signal amplified as described above, and proceed to step 832 in FIG.
Proceed to.

If S66 is YES, if the temperature remains below the lower limit for regeneration for 15 seconds, the S
34, the burner 25 is deactivated, and the process returns to Sl. On the other hand, if the detected temperature is 55 (11: or higher) in S63, the process proceeds to S67, where the glow plug 29 is oiled; heating is stopped, and S68, After determining the temperature in S69 and 57(l), the amount of fuel supplied is increased or decreased depending on the temperature. In other words, in S68 it is determined whether the temperature is 580°C or higher, and in the following cases, the drive signal for the fuel injection valve 30 is changed in S72. For example, the temperature is amplified by 1.4 times, and the process proceeds to S75.If the temperature is 580°C or higher in 368, then it is determined in 369 whether the temperature is 600°C or higher, and in the following cases, the drive signal is amplified to 1.2 amplify it twice,
Proceed to S75. If S69 is over 600℃, further S
70 to determine whether the temperature is 620℃ or higher, and in the following cases, S
In step 74, the process proceeds to step S75 without amplifying the drive signal (1.0 times). In addition, if S71) is 620℃ or higher, S71
The drive signal is reduced by a factor of 0.8, for example, and the process proceeds to S75.

In this way, the amount of fuel supplied is controlled according to the temperature on the artificial side of the trap 23 to maintain the temperature within a temperature range suitable for regenerating the trap 23 (for example, 600 to 620° C.). From S75, the process proceeds to 832 in FIG. 8 as described above, and it is determined whether or not the predetermined playback time of the trap 23 has elapsed.

In the above-described embodiment, the control is performed as explained in S6, but it goes without saying that similar control can be performed by calculating P2/PI, P, /P, etc., for example.

Effects of the Invention As explained in detail above, the exhaust particulate collection device for an internal combustion engine according to the present invention determines whether or not regeneration by a burner is necessary based on the ratio of the trap inlet pressure and the trap outlet pressure. The trap can be regenerated accurately when a predetermined amount of trapped air is reached, regardless of the amount of engine intake air or the presence or absence of exhaust gas recirculation.
This often results in poor drivability, burnout of the trap, or waste of fuel due to premature regeneration. Moreover, since the pressure sensor is provided only for the trap inlet pressure, it is possible to reduce costs, and in particular, it is possible to use a pressure sensor with sufficiently high accuracy and excellent reliability and durability. becomes.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the configuration of a conventional exhaust particulate collector;
Figure 3 is a block diagram showing the configuration of the present invention, Figure 3 is a characteristic diagram showing the relationship between trap inlet pressure Pl and trap differential pressure ΔP, and Figure 4 shows the relationship between trap collection amount and ratio ΔP/P. FIG. 5 is a characteristic diagram showing the relationship between trap collection amount and trap inlet pressure "1 t F wrap outlet pressure P2,
FIG. 6 is a configuration explanatory diagram showing one embodiment of the present invention, and FIG.
FIG. 11 is a flowchart showing an example of the control program of this embodiment. A-... Trap, B... Burner, C... Rotation speed sensor, D... Load sensor E a... Pressure sensor, F... Trap outlet pressure setting means, G... Regeneration time determination Means, 23... trap, 25 φ burner,
29・Fist・Glow plug, 3O-II・Fuel injection valve, 3
2@e・Fuel tank, 33...Fuel pump, 34...
・Air pump, 35...-Electromagnetic three-way valve, 37...Pressure outlet, 3jJ-Reference pressure sensor, 40...Temperature sensor, 41...Rotational speed sensor, 42...Negative kinaut sensor, 50... Control device, 51... Grounding device, 52.
・War battery, 53...Relay, 54Φ-・CPU,
55@...Memory, 57.e.Multiplexer, 58.
-A, -D converter, 59...P engineering O (peripheral unit 10), 6 ('l...constant voltage device. 2 other people Figure 1 Figure 2 Figure 4th day j→1:Payment 4 !：KeHfufuu indigo heat -- Figure 7 Figure 8 r￥i Figure 9

Claims (1)

[Claims] (]) A trap for collecting exhaust particulates installed in the exhaust passage, a burner for incinerating the particulates collected in this trap and regenerating the trap, and a rotational speed of the engine. a rotational speed sensor for detecting, a load sensor for detecting engine load, a pressure sensor for detecting the inlet pressure of the trap, and a trap outlet for setting the trap outlet pressure based on the output signals of the rotational speed sensor and the load sensor. An internal combustion engine comprising a pressure setting means and a regeneration timing determining means for determining whether or not regeneration by the burner is necessary based on the ratio between the set trap outlet pressure and the trap inlet pressure detected by the pressure sensor. Engine exhaust particulate collection device. (2) The regeneration time determining means calculates the trap inlet pressure and determines whether or not regeneration is necessary by comparing the calculated result with a predetermined value. Exhaust particle collection device for internal combustion engines.