JPH0554057B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for measuring the amount of diesel particulate collected by a filter installed in the exhaust passage of a diesel engine, and is particularly effective for diesel engines equipped with an exhaust gas recirculation device. This invention relates to a method for measuring the amount of diesel particulate collected used in

As proposed in Japanese Patent Application No. 58-128781 filed by the present applicant, diesel particulate (hereinafter referred to simply as particulate) in the exhaust gas of a diesel engine clogs the filter that collects it, and Rather than causing a decrease in output,
This filter requires incineration of the particulate at certain times, and its regeneration takes place. When measuring the regeneration timing of this filter, feedback control is often performed by using the value of pressure change in the exhaust passage where the filter is installed, and activating the filter's reburning device when this value exceeds a set value. . However, when measuring the pressure change value in the exhaust passage, measurement errors are likely to occur if factors other than filter clogging are included. For example, diesel engines contain nitrogen oxides (NOx) in their exhaust gas.
In order to reduce the occurrence of such problems, an exhaust gas recirculation device (hereinafter simply referred to as an EGR device) is often installed to return a portion of the exhaust gas to the air supply path. Such an EGR device normally extracts exhaust gas from the exhaust manifold side of the engine and returns it to the intake manifold. For this reason, when the filter on the exhaust path side becomes clogged with particulate matter, the pressure on the upstream side of the filter rises, but the exhaust gas increases in response to a predetermined amount of exhaust gas recirculation (hereinafter simply referred to as EGR amount). Since the air returns to the air supply path side, the pressure on the upstream side of the filter changes greatly due to factors other than filter clogging, resulting in an inappropriate collection amount value. Moreover, although the EGR device reduces nitrogen oxides in the exhaust gas, it also increases particulate matter.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for measuring the amount of diesel particulate collected that can accurately measure the amount of particulate collected without being adversely affected by an exhaust gas recirculation device.

The present invention provides a recirculation amount control means for controlling the amount of recirculation of exhaust gas in a recirculation path connecting an exhaust path and an air supply path of a diesel engine, and a change in the amount of diesel particulate collected by a filter in the exhaust path. an engine rotation sensor that outputs engine rotation speed information of the diesel engine; and a lever that outputs lever opening information of a fuel injection pump of the diesel engine. An opening sensor,
The cross-sectional area of the recirculation path is maintained in a cut state using a collection amount measuring means that measures the collection amount based on the engine rotational speed, the lever opening degree, and the amount of change in exhaust passage pressure. Then, we measured in advance how the exhaust passage pressure would change when the engine rotation speed and the lever opening of the fuel injection pump were changed in various ways for one single collection amount. A collection amount map is created, and a collection amount setting map is created by collecting the single collection amount maps for each different single collection amount that were similarly created sequentially, and then,
The cross-sectional area of the recirculation path is controlled to a cut state by the recirculation amount control means, the current exhaust path pressure change amount is detected by the exhaust path pressure change amount detection means, and the The current rotational speed and lever opening degree are detected by the quantity measuring means, and then,
A single collection amount map that matches the current detection situation is selected from the collection amount setting map using a microcomputer, and the single collection amount corresponding to this single collection amount map is selected as the current collection amount. It is characterized by being understood as The present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a diesel engine 1 to which a method for measuring the amount of diesel particulate collected as an embodiment of the present invention can be applied. The air supply path I of this engine sucks atmospheric air through an air cleaner 2, pressurizes it with a compressor 3 of a supercharger, and supplies it into a cylinder (not shown) of the engine 1. On the other hand, the exhaust path E guides the exhaust gas discharged from the above-mentioned cylinder to the turbine 4 of the supercharger, and further discharges it into the atmosphere through a ceramic particulate collection filter 5, and then through a muffler 6. .
An exhaust passage E between the engine and the turbine 4 can communicate with an air supply passage I between the engine 1 and the compressor 3 through a bypass passage B. This bypass path is a part of the EGR device 7, and an EGR valve 8 that makes the cross-sectional area of the bypass path B variable is attached thereto. The EGR valve 8 has a diaphragm 802 integrated with a valve body 801, which is maintained in a balanced position with the pressure difference between an atmosphere open chamber 803 and a negative pressure chamber 804 and the elastic force of a return spring 805 in the valve closing direction. Ru. Note that the valve body 801 includes a position sensor 806 that can output a signal corresponding to the amount of lift from the valve closed position. The negative pressure chamber 804 can be communicated with the vacuum pump 10 or the atmosphere opening 901 via the solenoid valve 9 . This solenoid valve receives an output signal that changes the duty ratio from the microcomputer (hereinafter simply referred to as microcomputer) 11 side as a controller, and thereby changes the negative pressure value in the negative pressure chamber 804 in proportion to the increase in the duty ratio. It works to make it bigger. In other words, as the output signal increases, the valve body 801
The lift amount is increased, and the EGR amount is also increased.

On the upstream side of the exhaust passage E, which is the front side of the filter 5, a pressure sensor 12 for detecting the exhaust pressure P as the exhaust passage pressure that changes due to clogging of the filter, and a temperature sensor 13 for detecting the exhaust temperature are installed. , the output signals of these two sensors are input to the microcomputer 11.

Fuel injection pump 14 for diesel engine 1
is attached to the lever 15 for adjusting the injection amount of the pump, and a lever opening sensor 16 is attached to the lever 15 for adjusting the injection amount. Furthermore, an engine rotation sensor 17 consisting of a pulse generator that emits a number of pulses depending on the engine rotation speed is also attached to this pump. Both these sensors 1
6 and 17 are also given output signals to the microcomputer 11.

Furthermore, the microcomputer 11 is also provided with output signals from a water temperature sensor 18 that detects the temperature of cooling water and an accelerator opening sensor 19, respectively.

In the diesel engine 1 as described above,
To measure the amount of particulate matter collected, () The microcomputer 11 functions as a recirculation amount control means for controlling the amount of recirculation of exhaust gas in the bypass path B, and the operating range of the diesel engine is set to at least one of the following. It is determined whether the EGR is in the EGR cut range.

B. Is the cooling water temperature lower than the set value (for example, 50℃)? In this case, the microcomputer makes a judgment based on the output signal input from the water temperature sensor 18, and when the temperature is below the EGR cut range, the microcomputer stops the output to the solenoid valve 9, and returns the valve body to the closed position by the return spring 805. Keep 801 and shut off EGR gas.

(b) Determine whether or not the vehicle is in the deceleration operation range. In this case, the microcomputer 11 is the accelerator opening sensor 1.
Based on the output signal from 9, if it is determined that the deceleration operation range is reached, EGR gas is shut off in the same way as in a).

() When it is determined that the previous judgment result is not within the EGR cut range, the subsequent measurement is stopped and preparations are made for the next measurement process. On the other hand, if it is determined that the EGR is in the cut region, the microcomputer 11 controls the lever opening sensor 16, engine rotation sensor 17, and pressure sensor 1.
Based on the respective output signals of 2 and 2, the particulate collection amount is measured from a particulate collection amount setting map which is a collection of single collection amount maps f1, f2, . . . fx as shown in FIG.

In addition, the single collection amount map f1 used here,
The collection amount setting map, which is a collection of f2, . . . fx (see Fig. 2), is created in advance as follows.

That is, the cross-sectional area of the recirculation path is maintained in the EGR cut state, and then the single collection amount map f is sequentially changed according to the increase/decrease in the collection amount.
1, f2, ...fx are created. First, in creating the single collection amount map f1, the collection amount (here, the minimum value) is constant, and the engine rotation speed Ne and the lever opening degree θ of the fuel injection pump are
We actually measure how the pressure drop value (pressure difference between the standard pressure and the current exhaust pressure) changes in accordance with the change in the Create a quantity map fx.
Furthermore, the single collection amount map fx for each of the other different collection amounts is based on the engine rotational speed Ne and the fuel injection pump lever opening θ, assuming that the collection amount is constant.
We sequentially measure how the set pressure drop value A changes depending on the change, and create a single collection amount map fx that is different from each other.

In this way, the single collection amount map f
The collection amount setting map, which is a collection of 1, f2, ...fx, sets the set pressure drop value A according to the engine rotational speed Ne and the lever opening θ of the fuel injection pump to the collection amount W of diesel particulate. Therefore, 3 values were set for each collection amount as values that change.
It consists of a dimensional map.

The microcomputer 11, which has been stored with such a collection amount setting map, performs the following operations in the EGR cut area:
Thereafter, it functions as an exhaust passage pressure change amount detecting means and detects a pressure loss value that is the current exhaust passage pressure change amount. Furthermore, it functions as a means for measuring the amount of collected
The current engine rotational speed Ne and the lever opening θ of the fuel injection pump are detected, and then the pressure drop value A corresponding to the current engine rotational speed Ne and the lever opening θ of the fuel injection pump is mapped to each single collection amount map. f1, f2, ... fx are calculated respectively, and from among the calculated pressure loss values A for each single collection amount map, a single one having the same value as the currently detected pressure loss value is selected. Select the collection amount map fx,
The collected amount W corresponding to the same map is the current collected amount W
Measure as.

Using the collected amount W obtained as a result of the collected amount measurement performed in the order of () and () above, after this,
Corrects the EGR amount after leaving the EGR cut area.
In this case, a map of the lift amount h (third
Select the correction value αx corresponding to the lift amount h obtained from Calculate,
Will hold the EGR valve at the same value.

Furthermore, the collected amount W can also be used to measure the timing of activation of a reburning device for incinerating the particulate matter of the filter 5 (not shown).

In the above, in the first step ()
Although a judgment was made as to whether or not it was in the EGR cut region, instead of this, the following process may be performed.
That is, when starting to measure the collected amount, first, () the EGR valve 8 is set to the closed state and EGR cut is forcibly performed.

() While in the forced EGR cut area due to the processing in (), the microcomputer finds the corresponding point on the map as shown at f1 in Figure 2 in the same way as described above.
From that position, the corresponding point of the pressure loss value A is further determined.
That is, the pressure loss value A based on the output of the pressure sensor 12
, select an fx map with a value equal to this.
Then, the amount W of particulate collected is measured from the fx map. After measuring the collected amount in the forced EGR cut area in this way, the correction value αx based on this collected amount is used to calculate the amount after leaving the forced EGR cut area.
EGR amount can be corrected.

Next, in each of the preceding stages () mentioned above, the EGR valve 8 is held in the closed position as the set state.
Although the EGR cut was performed, instead of this, the setting state may be maintained in a state determined by a two-dimensional map as shown in FIG. That is, () The EGR valve 8 is set to the lift amount h1 determined by the lever opening degree θ of the injection pump - the engine rotational speed Ne. In this case, the microcomputer first controls the EGR valve 8 to the lift amount h1 based on the output signals from the engine rotation sensor 17 and the lever opening sensor 16.

() While the EGR valve 8 is maintained in the set state (based on θ-Ne) through the processing in (), the microcomputer calculates the corresponding point on the g1 map as shown in Figure 5 in the same way as described above. Lever opening degree θ
Further, a gx map is determined in which the pressure loss value A1 increasing in the three-dimensional direction at the corresponding point is equal to the pressure loss value based on the output from the pressure sensor 12, and the particulate collection amount W is determined. In this case, unlike the above two examples, the collected amount can be measured at all times.

After measuring the collection amount W in the set reference EGR range in this way, the controller cancels this setting state. After that, using the correction value βx based on the measured collection amount, correct the lift amount h of the EGR valve based on the lever opening degree θ−engine rotation speed Ne, and maintain the EGR valve at this correction value h(βx). I can do it.

In addition, in the above, the exhaust pressure of the filter was detected by one pressure sensor 12, but it is also possible to calculate the pressure loss value by setting the reference value to atmospheric pressure and measuring this with another pressure sensor. good.

As mentioned above, in the method of the present invention, while the cross-sectional area of the recirculation path is maintained in the EGR cut state,
To measure the amount of patyculate collected,
The captured amount can be measured after ensuring a steady state by eliminating switching fluctuations on the EGR device side, and the measured value
Measurements will be accurate without unwanted pressure fluctuations caused by the EGR device. Moreover,
Using this measurement value, after leaving the measurement time limit
EGR valve lift amount correction can be performed accurately. Furthermore, the reburning timing of the filter 1 can also be accurately measured using this measured value.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a diesel engine to which the method of the present invention can be applied, and Figures 2 and 5 are the lever opening degree θ and engine rotational speed input to the microcomputer 11 used in different engines.
Three-dimensional pressure drop maps of Ne and collected amount, Figures 3 and 4 show the lever opening degree θ and engine rotational speed Ne input to different microcontrollers 11, respectively.
The lift amount h maps determined by the following are shown respectively. 1... Diesel engine, 5... Filter,
7...EGR device, 8...EGR valve, 801...
... Valve body, 11 ... Microcomputer, 12 ... Pressure sensor, 14 ... Injection pump, 16 ... Lever opening sensor, 17 ... Engine rotation sensor, I ... Air supply path, E ... Exhaust path, A ...Pressure drop, W...Collection amount,
h...Lift amount.

Claims (1)

[Scope of Claims] 1. A recirculation amount control means for controlling the amount of recirculation of exhaust gas in a recirculation path connecting an exhaust path and an air supply path of a diesel engine, and collection of diesel particulate by a filter in the exhaust path. an exhaust passage pressure change amount detection means for detecting an amount of exhaust passage pressure change due to a change in exhaust passage pressure; an engine rotation sensor that outputs engine rotation speed information of the diesel engine; and an engine rotation sensor that outputs information on a lever opening of a fuel injection pump of the diesel engine. using a lever opening degree sensor that outputs an output, and a trapped amount measuring means that measures the trapped amount based on the engine rotation speed, the lever opening degree, and the amount of change in exhaust passage pressure; It was estimated in advance how the exhaust passage pressure would change when the engine rotational speed and fuel injection pump lever opening were varied in a single collection amount while the cross-sectional area was kept in a cut state. A single collection amount map is created by actual measurement, and a collection amount setting map is created by collecting the single collection amount maps for each different single collection amount that were similarly created sequentially. , the cross-sectional area of the recirculation passage is controlled to a cut state by the recirculation amount control means, the current exhaust passage pressure change amount is detected by the exhaust passage pressure change amount detection means, and the The current rotational speed and lever opening degree are detected by the collection amount measuring means, and then a single collection amount map that matches the current detection situation is selected from the collection amount setting map using a microcomputer, and this single collection amount map is selected from the collection amount setting map. A method for measuring the amount of diesel particulate collected, characterized in that a single collected amount corresponding to a single collected amount map is determined as the current collected amount.